Advertisements
Feeds:
Posts
Comments

Archive for the ‘Calmodulin’ Category

Metabolic Genomics and Pharmaceutics, Vol. 1 of BioMed Series D available on Amazon Kindle


Metabolic Genomics and Pharmaceutics, Vol. 1 of BioMed Series D available on Amazon Kindle

Reporter: Stephen S Williams, PhD

 

Leaders in Pharmaceutical Business Intelligence would like to announce the First volume of their BioMedical E-Book Series D:

Metabolic Genomics & Pharmaceutics, Vol. I

SACHS FLYER 2014 Metabolomics SeriesDindividualred-page2

which is now available on Amazon Kindle at

http://www.amazon.com/dp/B012BB0ZF0.

This e-Book is a comprehensive review of recent Original Research on  METABOLOMICS and related opportunities for Targeted Therapy written by Experts, Authors, Writers. This is the first volume of the Series D: e-Books on BioMedicine – Metabolomics, Immunology, Infectious Diseases.  It is written for comprehension at the third year medical student level, or as a reference for licensing board exams, but it is also written for the education of a first time baccalaureate degree reader in the biological sciences.  Hopefully, it can be read with great interest by the undergraduate student who is undecided in the choice of a career. The results of Original Research are gaining value added for the e-Reader by the Methodology of Curation. The e-Book’s articles have been published on the Open Access Online Scientific Journal, since April 2012.  All new articles on this subject, will continue to be incorporated, as published with periodical updates.

We invite e-Readers to write an Article Reviews on Amazon for this e-Book on Amazon.

All forthcoming BioMed e-Book Titles can be viewed at:

https://pharmaceuticalintelligence.com/biomed-e-books/

Leaders in Pharmaceutical Business Intelligence, launched in April 2012 an Open Access Online Scientific Journal is a scientific, medical and business multi expert authoring environment in several domains of  life sciences, pharmaceutical, healthcare & medicine industries. The venture operates as an online scientific intellectual exchange at their website http://pharmaceuticalintelligence.com and for curation and reporting on frontiers in biomedical, biological sciences, healthcare economics, pharmacology, pharmaceuticals & medicine. In addition the venture publishes a Medical E-book Series available on Amazon’s Kindle platform.

Analyzing and sharing the vast and rapidly expanding volume of scientific knowledge has never been so crucial to innovation in the medical field. WE are addressing need of overcoming this scientific information overload by:

  • delivering curation and summary interpretations of latest findings and innovations on an open-access, Web 2.0 platform with future goals of providing primarily concept-driven search in the near future
  • providing a social platform for scientists and clinicians to enter into discussion using social media
  • compiling recent discoveries and issues in yearly-updated Medical E-book Series on Amazon’s mobile Kindle platform

This curation offers better organization and visibility to the critical information useful for the next innovations in academic, clinical, and industrial research by providing these hybrid networks.

Table of Contents for Metabolic Genomics & Pharmaceutics, Vol. I

Chapter 1: Metabolic Pathways

Chapter 2: Lipid Metabolism

Chapter 3: Cell Signaling

Chapter 4: Protein Synthesis and Degradation

Chapter 5: Sub-cellular Structure

Chapter 6: Proteomics

Chapter 7: Metabolomics

Chapter 8:  Impairments in Pathological States: Endocrine Disorders; Stress

                   Hypermetabolism and Cancer

Chapter 9: Genomic Expression in Health and Disease 

 

Summary 

Epilogue

 

 

Advertisements

Read Full Post »


Action of Hormones on the Circulation

Writer and Curator: Larry H. Bernstein, MD, FCAP 

 

 

Introduction

This is perhaps the most difficult piece to write, unexpectedly. I have done a careful search for related material using different search phrases.  It is perhaps because of the great complexity of the topic, which is inextricably linked to sepsis, the Systemic Inflammatory Response Syndrome SIRS), and is poised differently than the neural innervation of the hormonal response and circulation, as in the previous piece.  In the SIRS mechanism, we find a very large factor in glucocorticoids, the cytokine shower (IL-1, IL-6, TNF-α), and gluconeogenesis, with circulatory changes.  In this sequence, it appears that we are focused on the arteriolar and bronchial smooth muscle architecture, the adrenal medulla, vasoconstriction and vasodilation, and another set of peptide interactions.  This may be concurrent with the other effects described.

Related articles in Pharmaceutical Intelligence Journal:

Endothelial Function and Cardiovascular Disease

Pathologist and Author: Larry H Bernstein, MD, FCAP

https://pharmaceuticalintelligence.com/2012/10/25/endothelial-function-and-cardiovascular-disease/

Clinical Trials Results for Endothelin System: Pathophysiological role in Chronic Heart Failure, Acute Coronary Syndromes and MI – Marker of Disease Severity or Genetic Determination?

Curator: Aviva Lev-Ari, PhD, RN

https://pharmaceuticalintelligence.com/2012/10/19/clinical-trials-results-for-endothelin-system-pathophysiological-role-in-chronic-heart-failure-acute-coronary-syndromes-and-mi-marker-of-disease-severity-or-genetic-determination/

Endothelin Receptors in Cardiovascular Diseases: The Role of eNOS Stimulation

Author and Curator of an Investigator Initiated Study: Aviva Lev-Ari, PhD, RN

https://pharmaceuticalintelligence.com/2012/10/04/endothelin-receptors-in-cardiovascular-diseases-the-role-of-enos-stimulation/

Inhibition of ET-1, ETA and ETA-ETB, Induction of NO production, stimulation of eNOS and Treatment Regime with PPAR-gamma agonists (TZD): cEPCs Endogenous Augmentation for Cardiovascular Risk Reduction – A Bibliography

Curator of an Investigator Initiated Study: Aviva Lev-Ari, PhD, RN

https://pharmaceuticalintelligence.com/2012/10/04/inhibition-of-et-1-eta-and-eta-etb-induction-of-no-production-and-stimulation-of-enos-and-treatment-regime-with-ppar-gamma-agonists-tzd-cepcs-endogenous-augmentation-for-cardiovascular-risk-reduc/

Cardiovascular Disease (CVD) and the Role of Agent Alternatives in endothelial Nitric Oxide Synthase (eNOS) Activation and Nitric Oxide Production

Curator and Investigator Initiated Study: Aviva Lev-Ari, PhD, RN

https://pharmaceuticalintelligence.com/2012/07/19/cardiovascular-disease-cvd-and-the-role-of-agent-alternatives-in-endothelial-nitric-oxide-synthase-enos-activation-and-nitric-oxide-production/

Innervation of Heart and Heart Rate

Writer and Curator: Larry H Bernstein, MD, FCAP

https://pharmaceuticalintelligence.com/2015/02/15/innervation-of-heart-and-heart-rate/

αllbβ3 Antagonists As An Example of Translational Medicine Therapeutics

Larry H Bernstein, MD, FCAP, Reporter and curator

https://pharmaceuticalintelligence.com/2013/10/12/%CE%B1llb%CE%B23-antagonists-as-an-example-of-translational-medicine-therapeutics/

Cardiac Contractility & Myocardium Performance: Therapeutic Implications for Ryanopathy (Calcium Release-related Contractile Dysfunction) and Catecholamine Responses

Author, and Content Consultant to e-SERIES A: Cardiovascular Diseases: Justin Pearlman, MD, PhD, FACC

https://pharmaceuticalintelligence.com/2013/08/28/cardiac-contractility-myocardium-performance-ventricular-arrhythmias-and-non-ischemic-heart-failure-therapeutic-implications-for-cardiomyocyte-ryanopathy-calcium-release-related-contractile/

The Centrality of Ca(2+) Signaling and Cytoskeleton Involving Calmodulin Kinases and Ryanodine Receptors in Cardiac Failure, Arterial Smooth Muscle, Post-ischemic Arrhythmia, Similarities and Differences, and Pharmaceutical Targets

Larry H Bernstein, MD, FCAP, Justin Pearlman, MD, PhD, FACC and Aviva Lev-Ari, PhD, RN

https://pharmaceuticalintelligence.com/2013/09/08/the-centrality-of-ca2-signaling-and-cytoskeleton-involving-calmodulin-kinases-and-ryanodine-receptors-in-cardiac-failure-arterial-smooth-muscle-post-ischemic-arrhythmia-similarities-and-differences/

Ca2+-Stimulated Exocytosis:  The Role of Calmodulin and Protein Kinase C in Ca2+ Regulation of Hormone and Neurotransmitter

Larry H Bernstein, MD, FCAP
and
Aviva Lev-Ari, PhD, RN

https://pharmaceuticalintelligence.com/2013/12/23/calmodulin-and-protein-kinase-c-drive-the-ca2-regulation-of-hormone-and-neurotransmitter-release-that-triggers-ca2-stimulated-exocytosis/

Cardiac Contractility & Myocardium Performance: Ventricular Arrhythmias and Non-ischemic Heart Failure – Therapeutic Implications for Cardiomyocyte Ryanopathy (Calcium Release-related Contractile Dysfunction) and Catecholamine Responses

Justin Pearlman, MD, PhD, FACC, Larry H Bernstein, MD, FCAP and Aviva Lev-Ari, PhD, RN

https://pharmaceuticalintelligence.com/2013/08/28/cardiac-contractility-myocardium-performance-ventricular-arrhythmias-and-non-ischemic-heart-failure-therapeutic-implications-for-cardiomyocyte-ryanopathy-calcium-release-related-contractile/

Disruption of Calcium Homeostasis: Cardiomyocytes and Vascular Smooth Muscle Cells: The Cardiac and Cardiovascular Calcium Signaling Mechanism

Justin Pearlman, MD, PhD, FACC, Larry H Bernstein, MD, FCAP and Aviva Lev-Ari, PhD, RN

https://pharmaceuticalintelligence.com/2013/09/12/disruption-of-calcium-homeostasis-cardiomyocytes-and-vascular-smooth-muscle-cells-the-cardiac-and-cardiovascular-calcium-signaling-mechanism/

Calcium-Channel Blockers, Calcium Release-related Contractile Dysfunction (Ryanopathy) and Calcium as Neurotransmitter Sensor

Justin Pearlman, MD, PhD, FACC, Larry H Bernstein, MD, FCAP and Aviva Lev-Ari, PhD, RN

https://pharmaceuticalintelligence.com/2013/09/16/calcium-channel-blocker-calcium-as-neurotransmitter-sensor-and-calcium-release-related-contractile-dysfunction-ryanopathy/

Synaptotagmin functions as a Calcium Sensor: How Calcium Ions Regulate the fusion of vesicles with cell membranes during Neurotransmission

Larry H Bernstein, MD, FCAP and Aviva Lev-Ari, PhD, RN

https://pharmaceuticalintelligence.com/2013/09/10/synaptotagmin-functions-as-a-calcium-sensor-how-calcium-ions-regulate-the-fusion-of-vesicles-with-cell-membranes-during-neurotransmission/

Advanced Topics in Sepsis and the Cardiovascular System at its End Stage

Larry H Bernstein, MD, FCAP

https://pharmaceuticalintelligence.com/2013/08/18/advanced-topics-in-sepsis-and-the-cardiovascular-system-at-its-end-stage/

For most comprehensive Bibliography on the Ryanodine receptor calcium release channel complex and for FIGURES illustrating the phenomenon, see

Pharmacol Ther. 2009 August; 123(2): 151–177.

http://dx.doi.org:/10.1016/j.pharmthera.2009.03.006

PMCID: PMC2704947

Ryanodine receptor-mediated arrhythmias and sudden cardiac death

Lynda M. Blayney[low asterisk] and F. Anthony Lai

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2704947/

Oxidized Calcium Calmodulin Kinase and Atrial Fibrillation

Author: Larry H. Bernstein, MD, FCAP and Curator: Aviva Lev-Ari, PhD, RN

https://pharmaceuticalintelligence.com/2013/10/26/oxidized-calcium-calmodulin-kinase-and-atrial-fibrillation/

Contributions to cardiomyocyte interactions and signaling

Author and Curator: Larry H Bernstein, MD, FCAP  and Curator: Aviva Lev-Ari, PhD, RN

https://pharmaceuticalintelligence.com/2013/10/21/contributions-to-cardiomyocyte-interactions-and-signaling/

Cardiac Contractility & Myocardium Performance: Therapeutic Implications for Ryanopathy (Calcium Release-related Contractile Dysfunction) and Catecholamine Responses

Editor: Justin Pearlman, MD, PhD, FACC, Author and Curator: Larry H Bernstein, MD, FCAP, and Article Curator: Aviva Lev-Ari, PhD, RN

https://pharmaceuticalintelligence.com/2013/08/28/cardiac-contractility-myocardium-performance-ventricular-arrhythmias-and-non-ischemic-heart-failure-therapeutic-implications-for-cardiomyocyte-ryanopathy-calcium-release-related-contractile/

The Centrality of Ca(2+) Signaling and Cytoskeleton Involving Calmodulin Kinases and Ryanodine Receptors in Cardiac Failure, Arterial Smooth Muscle, Post-ischemic Arrhythmia, Similarities and Differences, and Pharmaceutical Targets

Larry H Bernstein, MD, FCAP, Justin Pearlman, MD, PhD, FACC and Aviva Lev-Ari, PhD, RN

https://pharmaceuticalintelligence.com/2013/09/08/the-centrality-of-ca2-signaling-and-cytoskeleton-involving-calmodulin-kinases-and-ryanodine-receptors-in-cardiac-failure-arterial-smooth-muscle-post-ischemic-arrhythmia-similarities-and-differen/

 Action of hormones on the circulation

Limbic system mechanisms of stress regulation: Hypothalamo-pituitary-adrenocortical axis

James P. Herman, Michelle M. Ostrander, Nancy K. Muelle, Helmer Figueiredo
Prog in Neuro-Psychopharmacol & Biol Psychiatry 29 (2005) 1201 – 1213
http://dx.doi.org:/10.1016/j.pnpbp.2005.08.006

Limbic dysfunction and hypothalamo-pituitary-adrenocortical (HPA) axis dysregulation are key features of affective disorders. The following review summarizes our current understanding of the relationship between limbic structures and control of ACTH and glucocorticoid release, focusing on the hippocampus, medial prefrontal cortex and amygdala. In general, the hippocampus and anterior cingulate/prelimbic cortex inhibit stress-induced HPA activation, whereas the amygdala and perhaps the infralimbic cortex may enhance glucocorticoid secretion. Several characteristics of limbic–HPA interaction are notable: first, in all cases, the role of given limbic structures is both region- and stimulus-specific. Second, limbic sites have minimal direct projections to HPA effector neurons of the paraventricular nucleus (PVN); hippocampal, cortical and amygdalar efferents apparently relay with neurons in the bed nucleus of the stria terminalis, hypothalamus and brainstem to access corticotropin releasing hormone neurons. Third, hippocampal, cortical and amygdalar projection pathways show extensive overlap in regions such as the bed nucleus of the stria terminalis, hypothalamus and perhaps brainstem, implying that limbic information may be integrated at subcortical relay sites prior to accessing the PVN. Fourth, these limbic sites also show divergent projections, with the various structures having distinct subcortical targets. Finally, all regions express both glucocorticoid and mineralocorticoid receptors, allowing for glucocorticoid modulation of limbic signaling patterns. Overall, the influence of the limbic system on the HPA axis is likely the end result of the overall patterning of responses to given stimuli and glucocorticoids, with the magnitude of the secretory response determined with respect to the relative contributions of the various structures.

representations of the HPA axis

representations of the HPA axis

Diagrammatic representations of the HPA axis of the rat. HPA responses are initiated by neurosecretory neurons of medial parvocellular paraventricular nucleus (mpPVN), which secretes ACTH secretagogues such as corticotropin releasing hormone (CRH) and arginine vasopressin (AVP) in the hypophysial portal circulation at the level of the median eminence. These secretagogues promote release of ACTH into the systemic circulation, whereby it promotes synthesis and release of glucocorticoids at the adrenal cortex.

When exposed to chronic stress, the HPA axis can show both response Fhabituation_ and response Ffacilitation_. FHabituation_ occurs when the same (homotypic) stressor is delivered repeatedly, and is characterized by progressive diminution of glucocorticoid responses to the stimulus. Systemic administration of a mineralocorticoid receptor antagonist is sufficient to block habituation, implying a role for MR signaling in this process. It should be noted that HPA axis habituation is highly dependent on both the intensity and predictability of the stressful stimulus. FFacilitation_ is observed when animals repeatedly exposed to one stimulus are presented with a novel (heterotypic). In chronically stressed animals, exposure to a novel stimulus results in rise in glucocorticoids that is as large as or greater than that seen in a chronic stress naıve animal. Importantly, facilitation can occur in the context of chronic stress-induced elevations in resting glucocorticoids levels, suggesting that this process involves a bypass or override of negative feedback signals.

Hippocampal regulation of the HPA axis appears to be both region- and stressor-specific. Using a sequential lesion approach, our group has noted that the inhibitory effects of the hippocampus on stress-induced corticosterone release and CRH/AVP mRNA expression are likely subserved by neurons resident in the ventral subiculum-caudotemporal CA1. In addition to spatial specificity, hippocampal regulation of the HPA axis also appears to be specific to certain stress modalities; our studies indicate that ventral subiculum lesions cause elevated glucocorticoid secretion following restraint, open field or elevated plus maze exposure, but not to ether inhalation or hypoxia.

The research posits an intricate topographical organization of prefrontal cortex output to HPA regulatory circuits. The anatomy of medial prefrontal cortex efferents may illuminate this issue. The infralimbic cortex projects extensively to the anterior bed nucleus of the stria terminalis, medial and central amygdala and the nucleus of the solitary tract, all of which are implicated in stress excitation. In contrast, the prelimbic cortex has minimal input to these structures, but projects to the ventrolateral preoptic area, dorsomedial hypothalamus and peri-PVN region, areas implicated in stress inhibition. Thus, the infralimbic and prelimbic/anterior cingulate components of the prefrontal cortex may play very different roles in HPA axis regulation. Like other limbic regions, the influence of the amygdala on the HPA axis is stressor- and region-specific. The medial amygdala shows intense c-fos induction following stressors such as restraint, swimming, predator exposure and social interaction.

Despite the prominent involvement of the hippocampus, medial prefrontal cortex and amygdala in HPA axis regulation, there is limited evidence of direct innervation of the PVN by these structures. Rather, these regions appear to project to a number of basal forebrain, hypothalamic and brainstem cell populations that in turn innervate the medial parvocellular PVN. Thus, in order to access principle stress effector neurons, information from the limbic system requires an intermediary synapse. In the bed nucleus of the stria terminalis and hypothalamus, the majority of these intermediary neurons are GABAergic. For example, the bed nucleus of the stria terminalis, ventrolateral preoptic area, dorsomedial hypothalamic nucleus and peri-PVN region all contain rich populations of neurons expressing the GABA marker glutamatic acid decarboxylase (GAD) 65/67.

The organization of the peri-PVN cell groups is particularly interesting. In the case of the ventral subiculum and to a lesser extent, the medial prefrontal cortex, terminal fields can be observed in the immediate surround of the PVN, corresponding to areas containing substantial numbers of GABA neurons. Importantly, dendrites of PVN neurons are largely confined within the nucleus proper, indicating that limbic afferents are unlikely to interact directly with the PVN neurons themselves. The peri-PVN GABA neurons are activated by glutamate, and likely express glutamate receptor subunits. These neurons also up-regulate GAD65 mRNA following chronic stress, commensurate with involvement in long-term HPA regulation. Injections of a general ionotroptic glutamate receptor antagonist into the PVN surround potentiates glucocorticoid responses to restraint, consistent with blockade of glutamate excitation of these GABA neurons. The data are consistent with an interaction between the excitatory limbic structures and inhibitory PVN-regulatory cells at the level of the PVN surround.

Brainstem stress-modulatory pathways likely relay excitatory information to the PVN. For example, the nucleus of the solitary tract provides both catecholaminergic (norepinephrine) and non-catecholaminergic (e.g., glucagon-like peptide-1 (GLP-1) input to the medial parvocellular. Norepinephrine is released into the PVN following stress and is believed to activate CRH neurons via alpha-1 adrenergic receptors. The role of this pathway is thought to be associated with systemic stressors, as selective destruction of PVN norepinephrine input using anti-dopamine beta hydroxylase-saporin conjugate blocks responses to 2-deoxy-glucose but not restraint.  In contrast, blockade of central GLP-1 receptors using exendin 9–36 markedly inhibits responsiveness to both lithium chloride and novelty, suggesting that this non-catecholaminergic cell population may play a more general role in stress integration.

The existence of these putative two-neuron circuits lends important insight into the nature of stress information processing. Anatomical data support the hypothesis that the vast majority of medial prefrontal cortex and ventral subicular inputs to subcortical stress relays are glutamate-containing. As can be appreciated, pyramidal cells of the medial prefrontal cortex and subiculum richly express mRNA encoding vesicular glutamate transporter-1 (VGlut1), a specific marker of glutamate neurons. Combined retrograde tracing/in situ hybridization studies performed in our lab indicate that the vast majority of cortical and hippocampal afferents to PVN-projecting regions (e.g., bed nucleus of the stria terminalis, dorsomedial hypothalamus, ventrolateral medial preoptic area) indeed contain VGlut1, verifying a glutamatergic input to these areas. In contrast, the majority of amygdalar areas implicated in stress regulation express glutamic acid decarboxylase (GAD) 65 or 67 mRNA, suggesting a GABAergic phenotype; indeed, the vast majority of medial and central amygdaloid projections to PVN relays are GABAergic.

representations of limbic stress-integrative pathways from the prefrontal cortex, amygdala and hippocampus

representations of limbic stress-integrative pathways from the prefrontal cortex, amygdala and hippocampus

Diagrammatic representations of limbic stress-integrative pathways from the prefrontal cortex, amygdala and hippocampus. The medial prefrontal cortex (mPFC) subsumes neurons of the prelimbic (pl), anterior cingulate (ac) and infralimbic cortices (il), which appear to have different actions on the HPA axis stress response. The pl/ac send excitatory projections (designated as dark circles, filled line with arrows) to regions such as the peri-PVN zone and bed nucleus of the stria terminalis (BST), both of which send direct GABAergic projections to the medial parvocellular PVN (delineated as open circles, dotted lines ending in squares). This two-neuron chain is likely to be inhibitory in nature. In contrast, the infralimbic cortex projects to regions such as the nucleus of the solitary tract (NTS), which sends excitatory projections to the PVN, implying a means of PVN excitation from this cortical region. The ventral subiculum (vSUB) sends excitatory projections to numerous subcortical regions, including the posterior BST, peri-PVN region, ventrolateral region of the medial preoptic area (vlPOA) and ventrolateral region of the dorsomedial hypothalamic nucleus (vlDMH), all of which send GABAergic projections to the PVN and are likely to communicate transsynaptic inhibition. The medial amygdaloid nucleus (MeA) sends inhibitory projections to GABAergic PVN-projecting populations, such as the BST, vlPOA and peri-PVN, eliciting a transsynaptic disinhibition. A similar arrangement likely exists for the central amygdaloid nucleus (CeA), which sends GABAergic outflow to the ventrolateral BST and to a lesser extent, the vlDMH. The CeA also projects to GABAergic neurons in the NTS, which may disinhibit ascending projections to the PVN.

Inotropes and vasopressors: more than haemodynamics!

Hendrik Bracht, E Calzia, M Georgieff,  J Singer, P Radermacher and JA Russell
British Journal of Pharmacology (2012) 165 2009–2011
http://dx.doi.org:/10.1111/j.1476-5381.2011.01776.x

Circulatory shock is characterized by arterial hypotension requiring fluid resuscitation combined with inotropes and/or vasopressors to correct the otherwise life-threatening impairment of oxygen supply to peripheral tissues. Catecholamines represent the current therapeutic choice, but this standard is only based on empirical clinical experience. Although there is evidence that some catecholamines may be better than others, it is a matter of debate which one may be the most effective and/or the safest for the different situations. In their review in this issue of the British Journal of Pharmacology, Bangash et al. provide an overview of the pharmacology as well as the available clinical data on the therapeutic use of endogenous catecholamines, their synthetic derivatives and a range of other agents (vasopressin and its analogues, PDE inhibitors and levosimendan). The authors point out that, despite well-established receptor pharmacology, the clinical effects of these treatments are poorly understood. Hence, further investigations are essential to determine which catecholamine, or, in a broader sense, which alternative vasopressor and/or inotrope is the most appropriate for a particular clinical condition.

LINKED ARTICLES   This article is a commentary on Bangash et al., pp. 2015–2033 of this issue and is commented on by De Backer and Scolletta, pp. 2012–2014 of this issue. To view Bangash et al. visit http://dx.doi.org/10.1111/j.1476-5381.2011.01588.x   and to view De Backer and Scolletta visit http://dx.doi.org/10.1111/j.1476-5381.2011.01746.x

In the present issue of the British Journal of Pharmacology, Bangash et al. (2012) review the pharmacology as well as the available clinical data on the therapeutic use of various inotropes and vasopressor agents used for the hemodynamic management of (septic) shock. By definition, circulatory shock is characterized by arterial hypotension that necessitates immediate intervention to maintain the balance of tissue oxygen supply and demand. In practice, the longer and the more frequent periods of hypotension are present in a patient, the less likely is survival, and early aggressive resuscitation is associated with improved outcome. Besides fluid administration to increase the circulating blood volume, in most cases, vasoactive drugs are required to restore an adequate perfusion pressure, and up to now, catecholamines represent the current therapeutic choice. According to their pharmacological profile, catecholamines are traditionally used for their predominant inotropic, vasodilating or constrictor effects.

Clinicians should not forget two fundamental aspects of catecholamine action. First, because of the ubiquitous presence of adrenoceptors, endogenous catecholamines. as well as their synthetic derivatives, have pronounced effects on virtually all tissues (many of which were described several years ago), in particular on the immune system (van der Poll et al., 1996; Flierl et al., 2008), on energy metabolism (Cori and Cori, 1928; Bearn et al., 1951) and on gastrointestinal motility (McDougal and West, 1954). Second, the adrenoceptor density and responsiveness to catecholamines are markedly altered by both the underlying disease and the ongoing catecholamine. Bangash et al. (2012) have to be commended that they not only describe the various endogenous catecholamines and their synthetic derivatives but also thoroughly discuss possible alternatives, such as vasopressin and its analogues, PDE inhibitors and levosimendan.

Inhibitory effects of cortisone and hydrocortisone on human Kv1.5 channel currents

Jing Yu, Mi-Hyeong Park, Su-Hyun Jo
Eur J Pharmacol 746 (2015) 158–166  http://dx.doi.org/10.1016/j.ejphar.2014.11.007

Glucocorticoids are the primary hormones that respond to stress and protect organisms from dangerous situations. The glucocorticoids hydrocortisone and its dormant form, cortisone, affect the cardiovascular system with changes such as increased blood pressure and cardioprotection. Kv1.5 channels play a critical role in the maintenance of cellular membrane potential and are widely expressed in pancreatic β-cells, neurons, myocytes, and smooth muscle cells of the pulmonary vasculature. We examined the electrophysiological effects of both cortisone and hydrocortisone on human Kv1.5 channels expressed in Xenopus oocytes using a two-microelectrode voltage clamp technique. Both cortisone and hydrocortisone rapidly and irreversibly suppressed the amplitude of Kv1.5 channel current with IC50 values of 50.2 + 74.2 μM and 33.4 + 73.2 μM, respectively, while sustained the current trace shape of Kv1.5 current. The inhibitory effect of cortisone on Kv1.5 decreased progressively from – 10mV to +30 mV, while hydrocortisone’s inhibition of the channel did not change across the same voltage range. Both cortisone and hydrocortisone blocked Kv1.5 channel currents in a non-use-dependent manner and neither altered the channel’s steady-state activation or inactivation curves. These results show that cortisone and hydrocortisone inhibited Kv1.5 channel currents differently. Kv1.5 channels were more sensitive to hydrocortisone than to cortisone.

In conclusion, cortisone and hydrocortisones rapidly and irreversibly blocked human Kv1.5 channels expressed in Xenopus oocytes in a closed state without altering activation and inactivation gating. These data provide a possible mechanism for GC effects on the cardiovascular system. The detailed mechanism of the interaction between GCs and human Kv1.5 channels merits further exploration.

Inflammasome and cytokine blocking strategies in autoinflammatory disorders

Monika Moll, Jasmin B. Kuemmerle-Deschner
Clinical Immunology (2013) 147, 242–275 http://dx.doi.org/10.1016/j.clim.2013.04.008

Autoinflammatory disorders are characterized by usually unprovoked recurrent episodes of features of inflammation caused by activation of the innate immune system. Many autoinflammatory disorders – the monogenetic defects in particular – are associated with alterations of inflammasomes. Inflammasomes are complex multimolecular structures, which respond to “danger” signals by activation of cytokines. Among these, IL-1 is the key player of the innate immune response and inflammation. Consequently, IL-1 blocking strategies are specific pathway targeting therapies in autoinflammatory diseases and applied in CAPS, colchicine-resistant FMF, TRAPS, HIDS and DIRA. A number of rare genetic disorders involve inflammasome malfunction resulting in enhanced inflammatory response. IL-1 inhibition to date is the most successful specific therapy in autoinflammatory disorders. Here, current treatment strategies in autoinflammatory disorders are reviewed with a focus on inflammasome and cytokine inhibition.

Autoinflammatory disorders have been defined as “clinical disorders marked by abnormally increased inflammation, mediated predominantly by the cells and molecules of the innate immune system.”  This means that in autoinflammatory disorders autoantibodies or antigen related T-cells are usually absent. These are features of the adaptive immune system and found in autoimmune diseases.
In general, autoinflammatory disorders are characterized by a large spectrum of rather non-specific systemic and organ-specific signs and symptoms of inflammation. In some diseases specific symptoms are observed like hearing loss in Muckle–Wells syndrome or CNS-disease in NOMID/CINCA. Most autoinflammatory disorders are associated with high levels of serum amyloid A (SAA) during inflammatory attacks and high risk of life-threatening amyloidosis. In most cases the disease will start in infancy and childhood. Only rarely primary manifestations in adulthood are reported.
Because recurrent fevers have been the most prominent feature of this group of diseases, historically they have been summarized under the term “hereditary periodic fever syndromes”.  With the deeper understanding of the underlying pathophysiologic mechanisms on the genetic and cellular level, the more comprehensive term “autoinflammatory syndromes”.
Along with the detection of the genetic origin of the autoinflammatory disorders, the cellular pathomechanism leading to the resulting inflammation has been described. A number of genes, which are affected by mutations in autoinflammatory disorders, encode proteins forming intracellular complexes called inflammasomes. External and endogenous “dangers” are recognized by these “danger sensors” and are able to induce an inflammatory reaction. Microbial components from infectious agents such as LPS, flagellin, lipoteichoic acid from bacteria, peptidoglycan or double-stranded DNA from viruses, or inorganic crystalline structures such as uric acid crystals, display pathogen-associated molecular patterns (PAMPs). These and endogenous damage-associated molecular patterns (DAMPs) like heat-shock proteins, the chromatin-associated protein high-mobility group box 1 (HMGB1), hyaluronan fragments, ATP, uric acid, and DNA which are released with cellular waste and injury stimulate the inflammasome. Also, the myeloid related proteins MRP8 and 14 (also known as S100A8 and S100A9) which are used as biomarkers, belong to the group of DAMPs. In addition to PAMPs and DAMPs, the inflammasome may interact with and be stimulated by proteins such as pyrin, proline–serine–threonine phosphatase interacting protein 1 (PSTPIP1), mevalonate kinase (MK) and NLRP7. All of these may also be altered in structure and function by monogenetic mutations.
As a consequence of inflammasome activation, a large variety of cytokines are produced and released by cells of the innate immune system (monocytes, macrophages, dendritic cells). They include the IL-1 family (IL-1, IL-18, IL-33), the TNF family (TNF-α, LT-α), the IL-6 family (IL-6, IL-11), the IL-17 family (IL-17A, IL-25), and type 1 IFNs (IFN-α, IFN-β). These cytokines play redundant roles depending on the cause and pathway of inflammation in the respective disease. Therefore, therapeutic strategies targeting only one cytokine should be expected to be inadequate to treat inflammatory disorders. However, improvement observed in diabetes mellitus Type 2 after blockade of IL-1 indicates that targeting one cytokine, even in a polygenic, complex inflammatory disorder, may cause beneficial effects. Regarding the inflammatory pathogenesis involved in the disease, Goldbach–Mansky and co-workers have classified the monogenetic autoinflammatory disorders as IL-1 mediated (CAPS and DIRA), partially IL-1 mediated (FMF, HIDS, PAPA) and mediated by other pathways (TRAPS, Blau-syndrome, Majeed’s syndrome, cherubism and IL-10 receptor deficiency).

Intracellular signaling pathways and therapeutic targets in autoinflammatory diseases. In autoinflammatory diseases, complex intracellular pathways lead to activation of the inflammatory response, particularly IL-1β activation and release, but also induction of NFκB and TNFα. Several mechanisms may activate the inflammasome, one crucial step in the IL-1 pathway. These include DAMPs (1), K+-efflux (2), activation of ROS (3) by ATP, anorganic crystals, membrane perturbation and proteases which are released from lysosomes damaged by β-amyloid, and heat shock proteins (4). NFκB may be induced by PAMPs via toll like receptors (5), IL-1β-signaling (6) or UPR (7). Activated NFκB eventually leads to the release of pro-inflammatory cytokines like IL-1, IL-6 and TNFα (8). Most of these steps to activation have been identified as targets for anti-inflammatory therapies, which are either already used in clinical practice or still experimental. IL-1- (a), TNF- (b), and IL-6 (c) inhibition are established safe and effective treatment strategies in many autoinflammatory diseases. Thalidomide (d) probably inhibits activation of IκB and is also part of routine treatment. Still experimental strategies include inhibition of PAMPs (e), DAMPs (f), potassium efflux (g), ROS by antioxidants (h), heat shock proteins (i), or caspase-1 (k). Caspase-inhibitors have entered clinical trials.

Colchicine has been used for the treatment of inflammatory disorders for centuries. Colchicine is effective in gout, but also in Behcet’s disease and FMF, where it is able to prevent amyloidosis. The drug affects many cell types and accumulates preferentially in neutrophils. Although its mode of action is still unclear it has microtubule destabilizing properties which may be part of its effects. Additional effects such as alteration of adhesion molecule expression, chemotaxis, and ROS generation also impact inflammation. Colchicine is generally tolerated well. However gastrointestinal, hematologic, and neuromuscular side-effects occur, when the administered dose is too high.

Inflammasome activation by heat shock proteins may be prevented by direct inhibition of HSP. HSP90 inhibition was effective in reducing gout-like arthritis in an animal model. Targeting caspase-1 (caspase-1-inhibitors) may be a strategy which has even greater potential in the treatment of autoimmune diseases and autoinflammatory disorders. IL-1 converting enzyme/caspase inhibitor VX-765 was able to inhibit IL-β-secretion in LPS-stimulated cells from FCAS and control subjects. A new IL-1 inhibitor, gevokizumab or Xoma 052 has entered clinical pilot trials. Therapeutic targets particularly for the protein-misfolding autoinflammatory diseases could be chemical chaperones and drugs that stimulate autophagy. Also inhibiting the signaling molecules that mediate the UPR activation which causes activation of the innate immune system and exacerbate inflammation could be a target.

To date IL-1 blockade is the most effective therapy in most monogenetic autoinflammatory diseases — in intrinsic and in extrinsic inflammasom-opathies. The most favorable effects are seen in the treatment of cryopyrin associated periodic syndromes like FACS, MWS and CINCA. But IL-1-blockade is also effective in other diseases like DIRA, TRAPS, PFAPA, colchicine-resistant FMF etc. IL-1 inhibition also has a role in multifactorial and common autoinflammatory diseases like diabetes, gout and artherosclerosis.

Endothelin—Biology and disease

Al-karim Khimji, Don C. Rockey
Cellular Signalling 22 (2010) 1615–1625
http://dx.doi.org:/10.1016/j.cellsig.2010.05.002

Endothelins are important mediators of physiological and pathophysiologic processes including cardiovascular disorders, pulmonary disease, renal diseases and many others. Additionally, endothelins are involved in many other important processes such as development, cancer biology, wound healing, and even neurotransmission. Here, we review the cell and molecular biology as well as the prominent pathophysiological aspects of the endothelin system.

Endothelin-1 (ET-1) was originally isolated from porcine aortic endothelial cells  and is a 21 amino acid cyclic peptide, with two disulphide bridges joining the cysteine amino acids (positions 1–15 and 3–11) at the N-terminal end and hydrophobic amino acids at the c-terminal end of the peptide (Fig. 1). The C-terminal end contains the amino acids that bind to the receptor, the N-terminal end determines the peptide’s binding affinity to the receptor (see Fig. 1). There appear to be at least 2 other endothelin isoforms including endothelin-2 (ET-2) and endothelin-3 (ET-3), which differ from ET-1 in two and six amino acid residues, respectively.

Endothelin (ET) structure

Endothelin (ET) structure

Endothelin (ET) structure. Endothelin is a 21 amino acid cyclic peptide, with two disulphide bridges joining the cysteine residues at positions 1–15 and 3–11. The C-terminal end containsamino acids that appear tomediate receptor binding,while the N-terminal residues determine the peptide’s binding affinity to the receptor. The amino acids highlighted in black in panels (b) and (c) show differences in ET-2 and ET-3 compared to ET-1. As can be seen, the remainder of the primary sequence of the different family members is identical.

Endothelin-1 biosynthetic pathway

Endothelin-1 biosynthetic pathway

Endothelin-1 biosynthetic pathway. Preproendothelin mRNA is synthesized via transcriptional activation of the preproendothelin gene. The translational product is a 203-amino acid peptide known as preproendothelin, which is cleaved at dibasic sites by furin-like endopeptidases to form big endothelins. These biologically inactive, 37- to 41-amino acid intermediates, are cleaved at Trp21–Val 22 by a family of endothelin-converting enzymes (ECE) to produce mature ET-1. The pathway for endothelin-2 and -3 is presumed to be similar.

The endothelin peptides are produced through a set of complex molecular processes. Preproendothelins are synthesized via transcriptional activation of the preproendothelin gene, which is regulated by c-fos and c-jun, nuclear factor-1, AP-1 and GATA-2. The translational product is a 203-amino acid peptide known as preproendothelin which is cleaved at dibasic sites by furin-like endopeptidases to form big endothelins. These biologically inactive 37- to 41-amino acid intermediates are cleaved at Trp21–Val 22 by a family of endothelin-converting enzymes (ECE) to produce mature ET-1.

Three isoforms of ECE have been reported, namely ECE-1, ECE-2 and ECE-3; ECE-1 and ECE-2 are most prominent. (Endothelin receptors are widely distributed in many different tissues and cells, there is a marked difference in cell and tissue distribution patterns between the two receptor subtypes i.e. ETA and ETB. [ET Receptors: Endothelial cells -ETB Vascular tone, clearance of circulating ET-1]).  ECEs belong to the M13 group of proteins—which is a family that includes neutral endopeptidases, kell blood group antigens (Kell), a peptide from phosphate regulating gene (PEX), X-converting enzyme (XCE), “secreted” endopeptidases, and the ECEs. M13 family members contain type II integral membrane proteins with zinc metalloprotease activity, and their function is inhibited by phosphoramidon. Four variants of ECE-1 have been reported in humans, namely ECE-1a, ECE-1b, ECE-1c and ECE-1d which are a result of alternate splicing of ECE-1mRNA. ECE-1 appears to be localized in the plasma cell membrane and its optimal activity is atpH7; it processes big ETs both intracellularly and on the cell surface. It is distributed predominantly in smooth muscle cells. ECE-1 can also hydrolyze other proteins including bradykinin, substance P, and insulin. ECE-2 is localized to the trans-Golgi network and is expressed abundantly in neural tissues and endothelial cells. Its optimal activity is at pH5; the acidic activity marks ECE-2 as an intracellular enzyme. Substrate selectivity experiments indicate that both ECE-1 and ECE-2 show preference for big ET-1 over big ET-2 or big ET-3.

Although there has been controversy about the precise repertoire of endothelin receptors, it appears that the endothelins exert their actions through two major receptor subtypes known as ETA and ETB receptors. ETA and ETB receptors belong to the superfamily of G-protein coupled receptors and contain seven transmembrane domains of 22–26 hydrophobic amino acids among approximately 400 total amino acids. The ETA receptor is found predominantly in smooth muscle cells and cardiac muscles, whereas the ETB receptor is abundantly expressed in endothelial cells.

ET-1 signaling is extremely complicated and ET receptor activation leads to diverse cellular responses through interaction in a chain of pathways that includes the G-protein-activated cell surface receptor, coupling G-proteins and phospholipase (PLC) pathway and other G protein-activated effectors. In one of the canonical signaling pathways, ETA induced activation of phospholipase C leads to the formation of inositol triphosphate and diacylglcerol from phosphatidylinositol. Inositol 1,4,5 triphosphate (IP3) then diffuses to specific receptors on the endoplasmic reticulum and releases stored Ca2+ into the cytosol. This causes a rapid elevation in intracellular Ca2+, which in turn causes cellular contraction and then vasoconstriction; the vasoconstrictive effects of ET persist despite dissociation of ET-1 from the receptor, perhaps because the levels of intracellular calcium remain elevated or because endothelin signaling pathways remain activated for prolonged time periods.

Endothelin signaling – smooth muscle cells

Endothelin signaling – smooth muscle cells

Endothelin signaling – smooth muscle cells. ET receptor stimulation leads to diverse cellular responses in a chain of pathways that include the G protein bg activation. This is followed by activation of a variety of different downstream cascades. For example, shown on the left, ETA induced activation of phosphatidyl inositol specific phospholipase C (PI-PLC) leads to the formation of inositol triphosphate (IP3) and diacylglcerol (DAG) from phosphoinositol 4,5 bisphosphate (PIP2). Inositol 1, 4, 5 triphosphate (IP3) then diffuses to specific receptors on the endoplasmic reticulum and releases stored Ca2+ into the cytosol. This causes a rapid elevation in intracellular Ca2+, which in turn causes cellular contraction

Endothelin signaling – endothelial cells.

Endothelin signaling – endothelial cells.

Endothelin signaling – endothelial cells. ET-1 stimulates NO production in endothelial cells by activation of endothelial cell NO synthase (eNOS). This occurs via ET-1’s activation of the ET-B receptor and the PI3-K/Akt pathway, which in turn stimulates phosphorylation of eNOS, with subequent conversion of L-arginine to L-citrulline and at the same time, generating NO. In addition shear stress, G-protein coupled receptors (GPCR), transient receptor potential channel (TRPC) and receptor tyrosine kinase (RTK) are also activators of eNOS. As a result, NO diffuses to stellate cell, where it directly activates the heme moiety of soluble guanylate cyclase, leading to the production of cyclic GMP. Intracellular cyclic GMP leads to activation of protein kinase G (PKG) resulting in relaxation of stellate cells – offsetting ET’s contractile effect on stellate cells.

The plasma levels of endothelin do not correlate with either the presence of essential hypertension or its severity, presumably, due to the fact that endothelin appears to be biologically active in a paracrine or autocrine fashion (i.e., rather than in an endocrine fashion. Systemic administration of ET-1 in low doses produces a modest increase in blood pressure which is normalized by selective ETA receptor blockade. In experimental models, long-term infusion with ET-1 leads to stroke and renal injury, which can be prevented with long-term administration of selective ETA receptor antagonists. Apart from its direct vasoconstrictor effects, mediated by smooth muscle cell contraction in the arterial system, ET-1 also indirectly enhances the vasoconstrictor effects of other neurohumoral and endocrine factors and may potentiate essential hypertension via this mechanism. For example, ET-1 induces conversion of angiotensin I to angiotensin II in in vitro models and stimulates adrenal synthesis of epinephrine and aldosterone. Thus there is cross-talk between the endothelin and renin–angiotensin–aldosterone systems—to synergistically act to facilitate vasoconstriction. In aggregate, the data suggest that dysregulation of the endothelin system contributes to multisystem complications of hypertension such as progressive renal disease, cerebrovascular diseases, atherosclerosis, and cardiac disease.

ET-1 in the renal system is synthesized in vascular endothelial cells and epithelial cells of the collecting ducts. Both ET receptors are present in renal vasculature and epithelial cells where ETB is the predominant receptor type. Renal vasculature is relatively more sensitive to the vasoconstrictive effects of ET-1 than any other vasculature and it causes constriction of both afferent and efferent renal arterioles.

ET-1 administration in humans significantly reduces renal blood flow, glomerular filtration rate and urine volume. In addition to its hemodynamic effects, ET-1 system is also involved in salt and water reabsorption, acid-base balance, promotion of mesangial cell growth and activation of inflammatory cells. ET-1 has been implicated in the pathophysiology of acute renal injury, chronic renal failure as well as renal remodeling. Transgenic mice overexpressing ET-1 develop glomerulosclerosis, interstitial fibrosis and reduced renal function. Increased ET-1 and ET receptor upregulation has been described in various animal models of acute renal injury and also in patients with chronic renal failure. Additionally, plasma ET-1 levels have been shown to correlate with the severity of chronic renal failure.

ET-1 is produced and released by airway epithelial cells, macrophages, and pulmonary vascular endothelial cells. Endothelin receptors are similarly widely distributed in airway smooth muscle cells, the pulmonary vasculature, and in the autonomic neuronal network lining tracheal muscles. ET-1 has a potent bronchoconstrictor effect.  In animal models, intravenous ET-1 injection led to a dose-dependent increase in airway resistance. The increase in airway resistance is in part due to enhanced production of thromboxanes with subsequent activation of thromboxane receptors and smooth muscle cell proliferation. The ET system has been emphasized in a number of pulmonary disorders, including asthma, cryptogenic fibrosing alveolitis, and pulmonary hypertension. Increased lung vasculature ET-1 immunoreactivity has been reported in both animals and patients with pulmonary hypertension and increases in ET-1 immunoreactivity correlate with the degree of pulmonary vascular resistance, disorders such as pulmonary hypertension, myocardial infarction, heart failure, neoplasia, vascular disorders, wound healing, and many others.

Endothelin and endothelin antagonism: Roles in cardiovascular health and disease

Praveen Tamirisa, William H. Frishman, and Anil Kumar
Am Heart J 1995;130:601-10

Endothelin is a naturally occurring polypeptide substance with potent vasoconstrictive actions. It was originally described as endotensin or endothelial contracting factor in 1985 by Hickey et al., who reported on the finding of a potent stable vasoconstricting substance produced by cultured endothelial cells. Subsequently, Yanagisawa et al. isolated and purified the substance from the supernatant of cultured porcine aortic and endothelial
cells and then went on to prepare its complementary deoxyribonucleic acid (cDNA). This substance was renamed endothelin.

Endothelin is the most potent vasoconstrictor known to date. Its chemical structure is closely related to certain neurotoxins (sarafotoxins) produced by scorpions and the burrowing asp (Atractaspis engaddensis).  Endothelins have now been isolated in various cell lines from several organisms. They are now considered to be autocoids or cytokines 4 because of their wide distribution, their expression during ontogeny and adult life, their primary role as intracellular factors, and the complexity of their biologic effects.

The superfamily of endothelins and sarafotoxins have two main branches with four members each. Endothelin is a polypeptide consisting of 21 amino acids. There are three closely related isoforms endothelin-1, endothelin-2, and endothelin-3 (ET1, ET2, and ET3, respectively), which differ in a few of the amino acid constituents. The fourth member, called ET4 or vasoactive intestinal constrictor, is considered to be the murine form ofET2. The endothelin molecules have several conserved amino acids, including the last six carboxyl (C)-terminal amino acids and four cysteine residues, which form two intrachain disulfide bonds between residues 1 and 15 and 3 and 11. These residues may have biologic implications particularly in relation to three dimensional structure and function. The main differences in the endothelin isopeptides reside in their amino (N)-terminal segments. There is a very high degree of sequence similarity between the two branches (approximately 60%) and within the constituent members of a branch (71% to 95%).

Endothelin has been demonstrated to be produced from endothelial and nonendothelial cells. The synthesis of endothelins parallels that of the various peptide hormones in that a precursor polypeptide is sequentially cleaved to generate the active form. Recently, endothelin-converting enzyme (ECE) was cloned. ECE acts at an essential step in the production of active forms of endothelins. The fully formed molecule is then broken down into inactive peptides by as yet uncharacterized proteases. Some candidates are the lysosomal protective protein (deamidase) and enkephalinase (neutral endopeptidase EC 24.11). The regulation of endothelin production occurs predominantly at the levels of transcription and translation. No storage
vesicles containing endothelin have been identified. The genes for the various endothelin isoforms have been sequenced and are found to be scattered in different chromosomes. Current evidence suggests that they arose from a common ancestor by exon duplication.

Factors known to release endothelinThrombinTransforming growth factor-~Arginine vasopressinHypoxia

Phorbol ester

Glucose

Angiotensin II

Cyclosporin

Insulinlike growth factor

Bombesin

Cortisol

Low-density lipeprotein cholesterol

Hypercholesterolemia

Changes in shear stress on vascular wall

Receptor affinities
Receptor Affinity
ETA ET1 > ET2 > ET3
ETB ET1 = ET2 = ET3
ETC ET3 > ET1
Intracellular signal transduction pathways activated by endothelins (ETs)

Intracellular signal transduction pathways activated by endothelins (ETs)

Intracellular signal transduction pathways activated by endothelins (ETs). Activated ET receptor stimulates phospholipase C (PLC) and phospholipase A2 (PLA2). Activated ET receptor also stimulates voltage-dependent calcium channels (VDC) and probably receptor-operated calcium channel (ROC). Inositol triphosphate (IP3) elicits release of calcium ion from caffeine-sensitive calcium store. Protein kinase C (PKC) activated by diacylglycerol (DG) sensitizes contractile apparatus. Increased concentration of intracellular free calcium ion ([Ca2+]i induces contraction. Cyclooxygenase products (prostacyclin [PGI2], prostaglandin E2 [PGE2], and thromboxane A2 [TXA2]) modify contraction. G, G protein; IP2, inositol biphosphate; IP3, inositol triphosphate; PIP2, phosphatidyl inositol biphosphate. (From Masaki T et al. Circulation 1991;84: 1460.)

Systemic hypertension. Endothelin is the most potent vasoconstrictor known to date and has an exceptionally long duration of physiologic action. The influence of endothelin in maintaining normal blood pressure and its role in the cause of systemic hypertension remain unclear. Intravenous injections of endothelin in animals cause a transient decrease in systolic blood pressure (ETB) followed by a prolonged pressor response (ETA). The vasoconstrictor action is mediated by ETA receptors in the vascular smooth muscle, whereas the predominant vasodilation effect is mediated by the ETB receptors on the endothelial cells that cause release of prostacyclin and nitric oxide. Therefore the overall predominant hemodynamic effect of endothelin in a given organ depends on the receptor type being stimulated, its location, and its relative abundance.

Angiotensin II has been found to increase endothelin concentrations in vitro from endo thelial cells, suggesting one mechanism by which angiotensin-converting-enzyme (ACE) inhibition could function in vivo. ACE inhibitors also can indirectly interfere with endothelin: increased concentrations of bradykinin decrease endothelin release (by acting through bradykinin 2 receptors, stimulation of which cause increased nitric oxide release). ACE inhibitors can cause regression of intimal hyperplasia, whereas other antihypertensive drugs are ineffective in this regard.

Myocardial ischemia. Myocardial ischemia can enhance the release of endothelin by cardiomyocytes and increase its vasoactive effects. Infusion of the ET1 isoform directly into the coronary circulation of animals results in the development of myocardial infarction, with impaired ventricular functioning and the development of arrhythmias. Endothelin has been shown to lower the threshold for ventricular fibrillation in dogs. An increase in ET1 has been observed in cardiac tissue after experimental myocardial infarction in rats, and pretreatment with an antiendothelin ϒ-globulin in this model can reduce infarct size by as much as 40%. Infusion of ETA receptor antagonist drugs before an ischemic insult can also reduce infarct size in animals.

Plasma endothelin concentrations can predict hemodynamic complications in patients with myocardial infarction. Patients with the highest plasma endothelin concentrations after myocardial infarction have the highest creatine phosphokinase (CPK) and CPK MB-isoenzyme concentrations and the lowest angiographically determined ejection fractions.

Left ventricular function and congestive heart failure. Endothelin exhibits potent inotropic activity in isolated hearts, cardiac muscle strips, isolated cells, and instrumented intact animals. High-affinity receptors for endothelin have been demonstrated in the atria and the ventricles. Intravenous administration of the ET1 isoform produces delayed prolonged augmentation of left ventricular performance in addition to its biphasic vasoactive effects of transient vasodilation followed by sustained vasocontraction.

Endothelin is a potent secretogogue of atrial natriuretic factor, which is a naturally occurring antagonist of endothelin. The ETA receptor appears to mediate endothelin’s actions of vasoconstriction and the stimulation of atrial natriuretic factor secretion, and the ETB receptor mediates endothelin-induced vasodilation and activation of the renin-angiotensin-aldosterone system. Urinary water excretion is mediated through both receptors, but sodium excretion is mediated through the ETA receptor.

Increased concentrations of endothelin described in patients with congestive heart failure are predictive of increased mortality risk. It also has been suggested that increased concentrations of endothelin may play an important role in the increased systemic vascular resistance observed in congestive heart failure.

There is early clinical evidence that treatment with ETA receptor antagonists and ECE inhibitors can influence favorably the course of human heart failure.  ACE inhibitors may also benefit patients with heart failure because of their antiendothelin actions.

Pulmonary hypertension. Expression of ET1 in the lung has been studied by immunocytochemistry and hybridization in situ in specimens from patients with pulmonary hypertension of primary or secondary causes. In contrast to normal lung, specimens from patients with pulmonary hypertension exhibit abundant ET2 immunostaining, particularly over endothelium of markedly hypertrophied muscular pulmonary arteries and plexogenic lesions. Endothelin has been suggested as a potent vasoconstrictor and growth-promoting factor in the pathophysiologic pathophysiologic mechanisms of pulmonary hypertension.

Ventricular and vascular hypertrophy. Endothelin increases DNA synthesis in vascular smooth-muscle ceils, cardiomyocytes, fibroblasts, glial cells, mesangial cells, and other cells; causes expression of protooncogenes; causes cell proliferation; and causes hypertrophy. It acts in synergy with various factors such as transforming growth factor, epidermal growth factor, platelet-derived growth factor, basic fibroblast growth factor and insulin to potentiate cellular transformation and replication. This synergy suggests that all of these factors act through common pathways involving PKC and cyclic adenosine monophosphate. Endothelin per se may not be a direct mediator of angiogenesis but may function as a comitogenic factor.

Neointima formation after vascular wall trauma. The efficacy of coronary angioplasty is limited by the high incidence of restenosis. ET1 induces cultured vascular smooth-muscle cell proliferation by activation of the ETA-receptor subtype, a response that normally is attenuated by an intact, functional endothelium. In addition, ET1 also induces the expression and release of several protooncogenes and growth factors that modulate smooth-muscle cell migration, proliferation, and matrix formulation. In addition to inhibiting smooth-muscle cell proliferation in vitro, endothelin-receptor antagonism with SB 209670 ameliorates the degree of neointima formation observed after rat carotid artery angioplasty. The observations raise the possibility that ET1 antagonists will serve as novel therapeutic agents in the control of restenosis.

Nonspecific endothelin antagonists
ECE inhibitorsAngiotensin-converting-enzyme inhibitorsAngiotensin II receptor blocking agentsCalcium-entry blocking agentsPotassium-channel opening agentsAdenosineNitroglycerin

 

 

 

 

SUMMARY

Endothelin is the most potent mammalian vasoconstrictor yet discovered. Its three isoforms play leading roles in regulating vascular tone and causing mitogenesis. The isoforms bind to two major receptor subtypes (ETA and ETB), which mediate a wide variety of physiologic actions in several organ systems. Endothelin may also be a disease marker or an etiologic factor in ischemic heart disease, atherosclerosis, congestive heart failure, renal failure, myocardial and vascular wall hypertrophy, systemic hypertension, pulmonary hypertension, and subarachnoid hemorrhage. Specific and nonspecific receptor antagonists and ECE inhibitors that have been developed interfere with endothelin’s function. Many available cardiovascular therapeutic agents, such as angiotensin-converting-enzyme inhibitors, calcium-entry blocking drugs, and nitroglycerin, also may interfere with endothelin release or may modify its activity. The endothelin antagonists have great potential as agents for use in the treatment of a wide spectrum of disease entities and as biologic probes for understanding the actions of endothelin in human beings.

Endothelin receptor antagonists

Sophie Motte, Kathleen McEntee, Robert Naeije
Pharmacology & Therapeutics 110 (2006) 386 – 414
http://dx.doi.org:/10.1016/j.pharmthera.2005.08.012

Endothelin receptor antagonists (ERAs) have been developed to block the effects of endothelin-1 (ET-1) in a variety of cardiovascular conditions. ET-1 is a powerful vasoconstrictor with mitogenic or co-mitogenic properties, which acts through the stimulation of 2 subtypes of receptors [endothelin receptor subtype A (ETA) and endothelin receptor subtype B (ETB) receptors]. Endogenous ET-1 is involved in a variety of conditions including systemic and pulmonary hypertension (PH), congestive heart failure (CHF), vascular remodeling (restenosis, atherosclerosis), renal failure, cancer, and cerebrovascular disease. The first dual ETA/ETB receptor blocker, bosentan, has already been approved by the Food and Drug Administration for the treatment of pulmonary arterial hypertension (PAH). Trials of endothelin receptor antagonists in heart failure have been completed with mixed results so far. Studies are ongoing on the effects of selective ETA antagonists or dual ETA/ETB antagonists in lung fibrosis, cancer, and subarachnoid hemorrhage. While non-peptidic ET-1 receptor antagonists suitable for oral intake with excellent bioavailability have become available, proven efficacy is limited to pulmonary hypertension, but it is possible that these agents might find a place in the treatment of several cardiovascular and non-cardiovascular diseases in the coming future.

Proposed mechanism by which ET-1 triggers vasoconstriction and vascular remodeling. Activation of G-protein-coupled endothelin receptors leads to stimulation of phospholipase C (PLC) which hydrolyses phosphatidyl inositol  biphosphate (PIP2) into inositol triphosphate (IP3) and diacylglycerol (DAG). DAG opens receptor-operated Ca++ channels (ROC) while IP3 induces Ca++ mobilization from the sarcoplasmic reticulum (SR) and opens store-operated Ca++ channels (SOC) directly or indirectly by store depletion to further increase cytosolic Ca++. This Ca++ increase may also trigger Ca++ release from the SR through ryanodine receptors. Depolarization induced by the opening of non-selective cationic channels (NSCC) via ET-1 and Ca++-activated Cl[1] channels as well as by the inhibition of voltage-gated K+ channels (Kv), opens voltage-dependent Ca++ channels (VDCC) to further increase the Ca++ entry across the plasma membrane. The cytosolic Ca++ increase may also activate Na/H exchangers resulting in alkalinization of the cells and promoting Ca++ influx by activating the Na/Ca exchanger. In addition, the elevated cytosolic Ca++ concentrations and DAG activate the protein kinase C and thus promote cell cycle progression by the Ca++/calmodulin complex (Ca++/CaM) and induction of proto-oncogenes. The intracellular signaling cascade induced by activation of ETB receptor is similar to the ETA receptor one, in stimulating the activation of PLC, generating IP3 and DAG and mobilizing of calcium. However, the PLA2 is also activated via ETB receptors to release prostaglandins (PG) and thromboxane A2 (TXA2).

Endothelin-1 increases isoprenaline-enhanced cyclic AMP levels in cerebral cortex

Marıa J. Perez-Alvareza, MC Calcerrada, F Hernandez, RE Catalan, AM Martınez
Regulatory Peptides 88 (2000) 41–46  PII: S0167-0115(99)00118-4

We examined the effect of ET-1 on cyclic AMP levels in rat cerebral cortex. The peptide caused a concentration-dependent increase of [3 H] cyclic AMP accumulation after 10 min of treatment. This effect was due to adenosine accumulation since it was inhibited by the treatment with adenosine deaminase. ET-1, apart from being able to increase cyclic AMP, also potentiated the cyclic AMP generated by isoprenaline in the presence of adenosine deaminase. Experiments performed in the presence of BQ-123 or BQ-788, specific ETA or ETB receptor antagonists respectively indicated that ET was the receptor involved. This effect was dependent on extracellular and B intracellular calcium concentration. These findings suggest that ET-1 plays a modulatory role in cyclic AMP generation systems in cerebral cortex.

Endothelins And Asthma

Roy G. Goldie and Peter J. Henry
Life Sciences I999; 65(1), pp. I-15, PI1 SOO24-3205(98)00614-6

In the decade since endothelin-1 (ET-l) and related endogenous peptides were first identified as vascular endothelium-derived spasmogens, with potential pathophysiological roles in vascular diseases, there has been a significant accumulation of evidence pointing to mediator roles in obstructive respiratory diseases such as asthma. Critical pieces of evidence for this concept include the fact that ET-l is an extremely potent spasmogen in human and animal airway smooth muscle and that it is synthesised in and released from the bronchial epithelium. Importantly, symptomatic asthma involves a marked enhancement of these processes, whereas asthmatics treated with anti-inflammatory glucocorticoids exhibit reductions in these previously elevated indices. Despite this profile, a causal link between ET-l and asthma has not been definitively established. This review attempts to bring together some of the evidence suggesting the potential mediator roles for ET-l in this disease.

Endothelial Cell Peroxisome Proliferator–Activated Receptor ϒ Reduces Endotoxemic Pulmonary Inflammation and Injury

Aravind T. Reddy, SP Lakshmi, JM Kleinhenz, RL Sutliff, CM Hart, and R. Reddy
J Immunol 2012; 189:5411-5420
http://www.jimmunol.org/content/189/11/5411

Bacterial endotoxin (LPS)-mediated sepsis involves severe, dysregulated inflammation that injures the lungs and other organs Bacterial endotoxin (LPS)-mediated sepsis involves severe, dysregulated inflammation that injures the lungs and other organs, often fatally. Vascular endothelial cells are both key mediators and targets of LPS-induced inflammatory responses. The nuclear hormone receptor peroxisome proliferator–activated receptor ϒ (PPARϒ) exerts anti-inflammatory actions in various cells, but it is unknown whether it modulates inflammation through actions within endothelial cells. To determine whether PPARϒ acts within endothelial cells to diminish endotoxemic lung inflammation and injury, we measured inflammatory responses and mediators in mice with endothelial-targeted deletion of PPARϒ. Endothelial cell PPARϒ (ePPARϒ) knockout exacerbated LPS-induced pulmonary inflammation and injury as shown by several measures, including infiltration of inflammatory cells, edema, and production of reactive oxygen species and proinflammatory cytokines, along with upregulation of the LPS receptor TLR4 in lung tissue and increased activation of its downstream signaling pathways. In isolated LPS-stimulated endothelial cells in vitro, absence of PPARϒ enhanced the production of numerous inflammatory markers. We hypothesized that the observed in vivo activity of the ligand-activated ePPARϒ may arise, in part, from nitrated fatty acids (NFAs), a novel class of endogenous PPARϒ ligands.
Supporting this idea, we found that treating isolated endothelial cells with physiologically relevant concentrations of the endogenous NFA 10-nitro-oleate reduced LPS-induced expression of a wide range of inflammatory markers in the presence of PPARϒ, but not in its absence, and also inhibited neutrophil mobility in a PPARϒ-dependent manner. Our results demonstrate a key protective role of ePPARϒ against endotoxemic injury and a potential ePPARϒ-mediated anti-inflammatory role for NFAs.

Endothelins in health and disease

Rahman Shah
European Journal of Internal Medicine 18 (2007) 272–282
http://dx.doi.org:/10.1016/j.ejim.2007.04.002

Endothelins are powerful vasoconstrictor peptides that also play numerous other roles. The endothelin (ET) family consists of three peptides produced by a variety of tissues. Endothelin-1 (ET-1) is the principal isoform produced by the endothelium in the human cardiovascular system, and it exerts its actions through binding to specific receptors, the so-called type A (ETA) and type B (ETB) receptors. ET-1 is primarily a locally acting paracrine substance that appears to contribute to the maintenance of basal vascular tone. It is also activated in several diseases, including congestive heart failure, arterial hypertension, atherosclerosis, endothelial dysfunction, coronary artery diseases, renal failure, cerebrovascular disease, pulmonary arterial hypertension, and sepsis. Thus, ET-1 antagonists are promising new agents. They have been shown to be effective in the management of primary pulmonary hypertension, but disappointing in heart failure. Clinical trials are needed to determine whether manipulation of the ET system will be beneficial in other diseases.

The production of ET receptors is affected by several factors. Hypoxia, cyclosporine, epidermal growth factor, basic fibroblast growth factor, cyclic AMP, and estrogen upregulate ETA receptors in some tissues, and C-type natriuretic hormone, angiotensin II, and perhaps basic fibroblast growth factor up-regulate ETB receptors. In contrast, the endothelins, angiotensin II, platelet-derived growth factor, and transforming growth factor down-regulate ETA receptors, whereas cyclic AMP and catecholamines down-regulate ETB receptors.

The ETA receptor contains 427 amino acids and binds with the following affinity: ET-1N>T-2>ET-3. It is predominantly expressed in vascular smooth muscle cells and cardiac myocytes. Its interaction with ET-1 results in vasoconstriction and cell proliferation. In contrast, the ETB receptor contains 442 amino acids and binds all endothelins with equal affinity. It is predominantly expressed on vascular endothelial cells and is linked to an inhibitory G protein. Activation of ETB receptors stimulates the release of NO and prostacyclin, prevents apoptosis, and inhibits ECE-1 expression in endothelial cells. ETB receptors also mediate the pulmonary clearance of circulating ET-1 and the re-uptake of ET-1 by endothelial cells.

All three endothelins cause transient endothelium dependent vasodilatation before the development of constriction, though this is most apparent for ET-1. Endothelins induce vasodilatation via the endothelial cell ETB receptors through generation of endothelium-derived dilator substances (Fig. 3), including nitric oxide (NO), which perhaps acts by physiologically antagonizing ETA receptor mediated vasoconstriction. The transient early vasodilator actions of the endothelins are attenuated by NO synthase inhibitors.  Additionally, ET-1 increases generation of prostacyclin by cultured endothelial cells, whereas cyclo-oxygenase inhibitors potentiate ET-1-induced constriction, suggesting that vasodilator prostaglandins play a similar modulatory role.

It has been proposed that ET-1 can affect vascular tone indirectly through its effect on the sympathetic nervous system, and it has been shown that that ET-1 may increase peripheral sympathetic activity through postsynaptic potentiation of the effects of norepinephrine. While in vitro low concentrations of ET-1 potentiate the effects of other vasoconstrictor hormones, including norepinephrine and serotonin, these findings have not been confirmed in vivo in the forearm resistance bed of healthy subjects.  In addition to its action on vascular vasomotion, ET-1 is thought to be a mediator in the vascular remodeling process. It seems that ET-1 interactions with the renin–angiotensin–aldosterone system play a significant role in this remodeling process.

Vascular actions of endothelin-1

Vascular actions of endothelin-1

Vascular actions of endothelin-1. Modified from – Galie N, Manes A, Branzi A; The endothelin system in pulmonary arterial hypertension. Cardiovasc Res 2004;61:227–37.

ET-1 appears to have a diverse role as a modulator of vascular tone and growth and as a mediator in many cardiovascular and non-cardiovascular diseases. To date, no disease entity, however, has been attributed solely to an abnormality in ET-1. Yet, ET-1 receptor antagonists have been studied in clinical trials involving a wide spectrum of cardiovascular diseases, though the only proven efficacy has been in patients with PAH.

Learning points

  • Endothelins are powerful vasoconstrictors and major regulators of vascular tone.
  • The endothelin (ET) family consists of three peptides (ET-1 ∼60%, ET-2 ∼30%, and ET-3 ∼10%) produced by a variety of tissues.
  • ET-1 is the principal isoform produced by the endothelium in the human cardiovascular system and appears to be foremost a locally acting paracrine substance rather than a circulating endocrine hormone.
  • Several human studies suggest that circulating ET-1 levels, which are elevated in heart failure and pulmonary hypertension, correlate with the prognosis of the disease.
  • ET-1 antagonists have been shown to be effective in the management of primary pulmonary hypertension, but disappointing in heart failure.
  • Clinical trials are needed to investigate the role of ET-1 receptor antagonists for other conditions, as ET-1 levels have been shown to be elevated in arterial hypertension, atherosclerosis, endothelial dysfunction, coronary artery disease, renal failure, cerebrovascular disease, and sepsis.

In Vitro Stability and Intestinal Absorption Characteristics of Hexapeptide Endothelin Receptor Antagonists

Hyo-kyung Han, BH Stewart, AM Doherty, WL Cody and GL Amidon
Life Sciences. I998; 63(18), pp. 1599-1609. PI1 SOO24-3205(98)00429-9

Endothelins are potent vasoconstrictor peptides which have a wide range of tissue distribution and three receptor subtypes (ETA ETB and ETC). Among the linear hexapeptide ETA / ETB receptor antagonists, PD 145065 (Ac-D-Bhg-L-Leu-L-Asp-L-Ile-L-Ile-L-Trp,  Bhg = (10,ll -dihydro-5H-dibenzo[a,d]cyclohepten-5-yl)-Gly) and PD 156252 (Ac-o-Bhg-L-Leu-L-Asp-L-Ile-(N-methyl)-L-Ile-L-Trp) were selected to evaluate the metabolic stability and intestinal absorption in the absence and/or in the presence of protease inhibitors. In vitro stability of both compounds was investigated in fresh plasma, lumenal perfusate, intestinal and liver homogenates. PD 156252 was more stable than PD 145065 in intestinal tissue homogenate (63.4% vs. 20.5% remaining) and liver homogenate (74.4% vs. 35.5 % remaining), while both compounds showed relatively good stability in the fresh plasma (94.5% vs. 86.7% remaining) and lumenal perfusate (85.8% vs. 72.3% remaining). The effect of protease inhibitors on the degradation of PD 145065 and PD 156252 was also investigated. Amastatin, thiorphan, chymostatin and the mixture of these three inhibitors were effective in reducing the degradation of both compounds. The pharmacokinetic parameters of PD 156252, calculated by using a non-compartmental model, were 6.95 min (terminal half-life), 191 mL (Vss), and 25.5 mL/min (Cltot) after intravenous administration in rats. The intestinal absorption of PD 156252 in rats was evaluated in the absence and/or in the presence of protease inhibitors. The results indicate that the major elimination pathway of PD 156252 appears to be the biliary excretion and protease inhibitors increase the intestinal absorption of PD 156252 through increasing metabolic stability.

Inhibitory and facilitatory presynaptic effects of endothelin on sympathetic cotransmission in the rat isolated tail artery

Violeta N. Mutafova-Yambolieva & David P. Westfall
British Journal of Pharmacology (1998) 123, 136 – 142

1 The present study was undertaken to determine the modulatory effects of the endothelin peptides on the neurogenically-induced release of endogenous noradrenaline (NA) and the cotransmitter adenosine 5′-triphosphate (ATP) from the sympathetic nerves of endothelium-free segments of the rat isolated tail artery. The electrical field stimulation (EFS, 8 Hz, 0.5 ms, 3 min) evoked over¯ow of NA and ATP, in the absence of endothelins, was 0.035+0.002 pmol mg71 tissue and 0.026+0.002 pmol mg71 tissue, respectively.

2 Endothelin-1 (ET-1; 1 ± 30 nM) significantly reduced the EFS evoked overflow of both NA and ATP.  The maximum inhibitory effect was produced by a peptide concentration of 10 nM, the amount of NA overflow being 0.020+0.002 pmol mg71 and that of ATP overflow 0.015+0.001 pmol mg71. Higher peptide concentrations (100 and 300 nM) reversed the EFS-evoked overflow of NA to control levels and that of ATP to above control levels. The inhibitory effect of ET-1 (10 nM) was resistant to the selective ETA receptor antagonist cyclo-D-Trp-D-Asp(ONa)-Pro-D-Val-Leu (BQ-123) but was prevented by ETB receptor desensitization with sarafotoxin S6c (StxS6c) or by ETB receptor blockade with N, cis-2,6-dimethyl-piperidinocarbonyl-L-gmethylleucyl-D-1-methoxycarbonyl-tryptophanyl-D-norleucine (BQ-788).

3 StxS6c, upon acute application, exerted a dual effect on transmitter release. At concentrations of 0.001 ± 0.3 nM the peptide significantly reduced the EFS-evoked NA overflow, whereas at concentrations of 1 ± 10 nM it caused a significant increase in the evoked overflow of both ATP and NA. Both the maximum inhibitory effect of StxS6c at a concentration of 0.003 nM approximately 85% reduction of NA overflow and 40% of ATP overflow) and the maximum facilitatory effect of the peptide at a concentration of 3 nM (approximately 400% increase of ATP overflow and 200% of NA overflow) were completely antagonized by either BQ-788 or by StxS6c-induced ETB receptor desensitization.

4 ET-3 (10 ± 100 nM) did not a€ect the EFS evoked overflow of either ATP or NA, but at a concentration of 300 nM significantly potentiated the release of both transmitters (0.118+ 0.02 pmol mg71 tissue ATP overflow and .077+0.004 pmol mg71 NA overflow). This effect was prevented either by BQ-123 or by BQ-788.

5 In summary, the endothelin peptides exerted both facilitatory and inhibitory effects on the neurogenically-induced release of the sympathetic cotransmitters ATP and NA in the rat tail artery. Both transmitters were modulated in parallel indicating that the endothelins do not differentially modulate the release of NA and ATP in this tissue.

Involvement of the central adrenomedullin peptides in the baroreflex

Meghan M. Taylo, Cynthia A. Keown, Willis K. Samson
Regulatory Peptides 112 (2003) 87– 93
http://dx.doi.org:/10.1016/S0167-0115(03)00026-0

The peptides derived from post-translational processing of preproadreno-medullin are produced in and act on areas of the autonomic nervous system important for blood pressure regulation. We examined the role of endogenous, brain-derived adrenomedullin (AM) and proadrenomedullin N-terminal 20 peptide (PAMP) in the central nervous system arm of the baroreflex by using passive immunoneutralization to block the actions of the endogenous peptides. Our results indicate that the preproadrenomedullin-derived peptides do not play a role in sensing changes in blood pressure (baroreflex sensitivity), but the adrenomedullin peptides do regulate the speed with which an animal returns to a normal, stable blood pressure. These findings suggest that endogenous, brain-derived AM and PAMP participate in the regulation of autonomic activity in response to baroreceptor activation and inactivation.

Pharmacological characterization of cardiovascular responses induced by endothelin-1 in the perfused rat heart

Keiji Kusumoto, A Fujiwara, S Ikeda, T Watanabe, M Fujino
Eur J Pharmacology 296 (1996) 65-74 SSDI 0014-2999(95)00680-X

The effects of the endothelin receptor antagonist TAK-044 (cyclo[D-α-aspartyl-3-[(4-phenylpiperazin-l-yl)carbonyl]-L-alanyl-L-α-aspartyl-D-2-(2-thienyl)-glycyl-L-leucyl-D-tryptophyl] disodium salt) and BQ-123 (cyclo[D-Asp-Pro-D-VaI-Leu-D-Trp]) were studied in the rat heart to characterize the receptor subtypes responsible for the cardiovascular actions of endothelin-1. Endothelin-1 induced a transient decrease and subsequent increase in perfusion pressure in perfused rat hearts, and increased left ventricular developed pressure. TAK-044 diminished these endothelin-l-induced responses (100 pmol/heart) with IC50 values of 140, 57 and 1.3 nM, respectively. BQ-123 (1-30/µM) partially inhibited the endothelin-l-induced hypertension (30-40%) in the rat heart, and failed to inhibit the hypotension. The positive inotropic effect of endothelin-1 was abolished by BQ-123. Neither indomethacin (10/µM) nor N’°-nitro-L-arginine methyl ester (100/pM) attenuated the  endothelin-l-induced hypotension. TAK-044 and BQ-123 attenuated the positive inotropic effect of endothelin-1 in rat papillary muscles. In rat cardiac membrane fractions, TAK-044 and BQ-123 inhibited [125I]endothelin-1 binding to endothelin ET A receptors with IC50 values of 0.39 + 0.6 and 36 + 9 nM, respectively, whereas only TAK-044 potently blocked the endothelin ET B receptor subtype (IC50 value: 370 + 180 nM). These results suggest that endothelin-1 modulates cardiovascular functions in the rat heart by activating both endothelin ET A and endothelin ET B receptors, all of which are sensitive to TAK-044.

Molecular Pharmacology and Pathophysiological Significance of Endothelin

Katsutoshi Goto, Hiroshi Hama and Yoshitoshi Kasuya
Jp J Pharmacol 1996; 72: 261-290

Since the discovery of the most potent vasoconstrictor peptide, endothelin, in 1988, explosive investigations have rapidly clarified much of the basic pharmacological, biochemical and molecular biological features of endothelin, including the presence and structure of isopeptides and their genes (endothelin- 1, -2 and -3), regulation of gene expression, intracellular processing, specific endothelia converting enzyme (ECE), receptor subtypes (ETA and ETB), intracellular signal transduction following receptor activation, etc. ECE was recently cloned, and its structure was shown to be a single transmembrane protein with a short intracellular N-terminal and a long extracellular C-terminal that contains the catalytic domain and numerous N-glycosylation sites. In addition to acute contractile or secretory actions, endothelin has been shown to exert long-term proliferative actions on many cell types. In this case, intracellular signal transduction appears to converge to activation of mitogen-activated protein kinase. As a recent dramatic advance, a number of non-peptide and orally active receptor antagonists have been developed. They, as well as current peptide antagonists, markedly accelerated the pace of investigations into the true pathophysiological roles of endogenous endothelin-1 in mature animals.

The discovery of endothelin in 1988 soon triggered explosive investigations of a worldwide scale, presumably due to its unusual characteristics; i.e., marked potency and long-lasting pressor actions. As a result, most of the basic problems concerned with the science of endothelin have rapidly been solved; e.g., features and regulations of the expression of endothelin genes,  biosynthetic pathways including characterization and cloning of endothelin converting enzyme, pharmacological, biochemical and molecular-biological identification of endothelin receptor subtypes, intracellular signal transduction following receptor activation, and discovery of various receptor agonists and antagonists. In addition to its potent cardiovascular actions, endothelin-1 shows a wide variety of biological effects, including contraction of nonvascular smooth muscle (intestinal, tracheal, broncheal, mesangial, bladder, uterine and prostatic smooth muscle), stimulation of neuropeptides, pituitary hormone and atrial natriuretic peptide release and aldosterone biosynthesis, modulation of neurotransmitter release, and increase of bone resorption. Furthermore, endothelin-1 has mitogenic properties and causes proliferation and hypertrophy of a number of cell types, including vascular smooth muscle cells, cardiac myocytes, mesangial cells, bronchial smooth muscle cells and fibroblasts. Endothelin-1 also induces the expression of several protooncogenes (c fos, C -Jun, c-myc, etc.).

These actions, whereby endothelin- 1 might influence the development of cellular hypertrophy/hyperplasia, are of potential significance in pathophysiological conditions associated with long-term changes in cardiovascular tissues, e.g., hypertension, myocardial infarction, chronic heart failure, vascular restenosis following balloon angioplasty, and atherosclerosis. These pathophysiological conditions are usually associated with increased plasma levels of endothelin-1, although the correlation is relatively poor. Nevertheless, a considerable increase in the tissue content of endothelin-1 has been gradually uncovered in many cases of these conditions. Even if the concentration of endothelin-1 at the cell surface is not high enough to induce contraction, it is well known that subthreshold concentrations of endothelin will enhance or potentiate the contraction produced by other vasoconstrictors (e.g., norepinephrine, serotonin, angiotensin II), indicating the existence of cross-talk among various vasoactive substances. Another important cross-talk among these substances may be mutual enhancement or inhibition of their expression in various tissues. In addition to these interactions, the true physiological and/or pathophysiological roles of each of the endothelin family peptide and receptor subtypes remain to be investigated.

Hydrogen Sulfide and Endothelium-Dependent Vasorelaxation

Jerzy Bełtowski, and Anna Jamroz-Wiśniewska
Molecules 2014, 19, 21183-21199; http://dx.doi.org:/10.3390/molecules191221183

In addition to nitric oxide and carbon monoxide, hydrogen sulfide (H2S), synthesized enzymatically from L-cysteine or L-homocysteine, is the third gasotransmitter in mammals. Endogenous H2S is involved in the regulation of many physiological processes, including vascular tone. Although initially it was suggested that in the vascular wall H2S is synthesized only by smooth muscle cells and relaxes them by activating ATP-sensitive potassium channels, more recent studies indicate that H2S is synthesized in endothelial cells as well. Endothelial H2S production is stimulated by many factors, including acetylcholine, shear stress, adipose tissue hormone leptin, estrogens and plant flavonoids. In some vascular preparations H2S plays a role of endothelium-derived hyperpolarizing factor by activating small and intermediate-conductance calcium-activated potassium channels. Endothelial H2S signaling is up-regulated in some pathologies, such as obesity and cerebral ischemia-reperfusion. In addition, H2S activates endothelial NO synthase and inhibits cGMP degradation by phosphodiesterase thus potentiating the effect of NO-cGMP pathway. Moreover, H2S-derived polysulfides directly activate protein kinase G. Finally, H2S interacts with NO to form nitroxyl (HNO)—a potent vasorelaxant. H2S appears to play an important and multidimensional role in endothelium-dependent vasorelaxation.

GPCR modulation by RAMPs

Debbie L. Hay, David R. Poyner, Patrick M. Sexton
Pharmacology & Therapeutics 109 (2006) 173 – 197
http://dx.doi.org:/10.1016/j.pharmthera.2005.06.015

Our conceptual understanding of the molecular architecture of G-protein coupled receptors (GPCRs) has transformed over the last decade. Once considered as largely independent functional units (aside from their interaction with the G-protein itself), it is now clear that a single GPCR is but part of a multifaceted signaling complex, each component providing an additional layer of sophistication. Receptor activity modifying proteins (RAMPs) provide a notable example of proteins that interact with GPCRs to modify their function. They act as pharmacological switches, modifying GPCR pharmacology for a particular subset of receptors. However, there is accumulating evidence that these ubiquitous proteins have a broader role, regulating signaling and receptor trafficking. This article aims to provide the reader with a comprehensive appraisal of RAMP literature and perhaps some insight into
the impact that their discovery has had on those who study GPCRs.

RAMPs were first identified during attempts to expression clone a receptor for the neuropeptide calcitonin gene related peptide (CGRP; McLatchie et al., 1998). Historical evidence had suggested that CGRP acted through a GPCR, as its binding had proven sensitive to GTP analogues and stimulation of various tissues and cells led to the accumulation of cAMP, suggesting activation of a Gs-coupled GPCR. However, attempts to clone such a receptor proved difficult. A putative canine CGRP receptor, RDC-1, was identified in 1995, but the original findings have not been replicated and current IUPHAR guidelines do not consider this receptor a genuine CGRP receptor (Kapas & Clark, 1995; Poyner et al., 2002). Shortly afterward, a further orphan receptor (CL, a close homologue of the calcitonin receptor) was shown to be activated by CGRP when transfected into HEK293 cells (Aiyar et al., 1996). This finding posed something of a conundrum since earlier attempts to examine the function of this receptor (or its rat homologue) in Cos 7 cells had not given positive results with CGRP.
Given the apparent functionality of the human CL receptor in HEK293 cells, the rat homologue was also transfected into this cell type and now responded to CGRP (Han et al., 1997). The authors speculated that there was a factor present in HEK293 cells that conferred high affinity for CGRP on the receptor.

In 1998, McLatchie and colleagues confirmed this speculation and provided new insights into the way that GPCRs and their pharmacology can be regulated (McLatchie et al., 1998). It was discovered that a novel family of single transmembrane domain proteins, termed RAMPs, was required for functional expression of CL at the cell surface, explaining why it had been so difficult to observe CGRP binding or function when CL was transfected into cells lacking RAMP expression (Fluhmann et al., 1995; Han et al., 1997; McLatchie et al., 1998). RAMPs were first identified from a library derived from SK-N-MC cells, cells known to express CGRP receptors. An expression-cloning strategy was utilized, whereby an SK-N-MC cDNA library was transcribed and the corresponding cRNA was used for injection into Xenopus oocytes. Cystic
fibrosis transmembrane regulator chloride conductance, a reporter for cAMP formation, was strongly potentiated by a single cRNA pool (in the presence of CGRP). Subsequently, a single cDNA encoding a 148-amino-acid protein comprising RAMP1 was isolated. The structure of the protein was unexpected, as it was not a GPCR and it did not respond to CGRP in mammalian cells. Thus, it was postulated that RAMP1 might potentiate CGRP receptors. A CL/RAMP1 co-transfection experiment supported this hypothesis.

CGRP/AM on the outside of the cell and did not simply act as anchoring/chaperone proteins for CL. RAMPs therefore provide a novel mechanism for modulating receptor–ligand specificity. The unique pharmacological profiles supported by RAMPs are discussed in later sections.

Fig. (not shown).  CGRP1 receptor-specific small molecule antagonists. The small molecule antagonist BIBN4096 BS (brown) is a specific antagonist of the CGRP1 receptor, acting at the interface between RAMP1 and the CL receptor to inhibit CGRP action. At least part of the binding affinity for BIBN4096 BS arises from interaction with Trp74 (red) of RAMP1. In contrast, antagonists that bind principally to the CL component of the complex will not discriminate between different CL/RAMP complexes.

The classic function attributed to RAMPs is their ability to switch the pharmacology of CL, thus providing a novel mechanism for modulating receptor specificity. Thus, the CL/RAMP1 complex is a high affinity CGRP receptor, but in the presence of RAMP2, CL specificity is radically altered, the related peptide AM being recognized with the highest affinity and the affinity for CGRP being reduced ¨100-fold. While AM is the highest affinity peptide, CGRP is recognized with moderate, rather than low affinity. Indeed, depending on the species and the form of CGRP (h vs. a), the separation between the 2 peptides can be as little as 10-fold (Hay et al., 2003a). This may particularly be true if receptor components of mixed species are used. The detailed pharmacology of the CGRP and AM receptors formed by RAMP interaction with CL has recently been reviewed (Born et al., 2002; Poyner et al., 2002; Hay et al., 2004; Kuwasako et al., 2004).

Fig. (not shown). The broadening spectrum of RAMP–receptor interactions. RAMPs can interact with multiple receptor partners. All RAMPs interact with the calcitonin receptor-like receptor (CL-R), the calcitonin receptor (CTR), and the VPAC1 receptor, while the glucagon and PTH1 receptors interact with RAMP2, the PTH2 receptor with RAMP3, and the calcium sensing receptor (CalS-R) with RAMP1 or RAMP3. The consequence of RAMP interaction varies. For the CL and CalS receptors, RAMPs play a chaperone role, allowing cell surface expression. For the CL and calcitonin receptors, RAMP interaction leads to novel receptor binding phenotypes . There is also evidence that RAMP interaction will modify signaling, and this has been seen for the VPAC1–RAMP2 heterodimer and for calcitonin receptor/RAMP complexes. In many instances, however, the consequence of RAMP interaction has yet to be defined.

Overall, the distribution data presented so far are supportive of the hypothesis that RAMP and CL or calcitonin receptor combinations are able to account for the observed CGRP, AM, and AMY pharmacology. A salient point for CGRP receptors relates to the cerebellum, where the lack of CL mRNA in some studies despite abundant CGRP binding has prompted speculation of alternative CGRP receptors (Oliver et al., 2001; Chauhan et al., 2003). Nevertheless, this apparent lack is study dependent and CL has been identified in cerebellum in other studies.

Some consideration has been given to the potential role that RAMPs may have in modifying receptor behaviors other than ligand binding pharmacology. An additional functional consequence might be that of alteration of receptor signaling characteristics.

While there is currently little evidence for signaling modifications of CL-based receptors in association with RAMPs, a completely different paradigm is evident for the VPAC1 receptor. This receptor has strong interactions with all 3 RAMPs, but its pharmacology, in terms of agonist binding, does not appear to be modified by their presence. On the other hand, there was a clear functional consequence of RAMP2 overexpression with the VPAC1 receptor where PI hydrolysis was specifically augmented relative to cAMP, which did not change. The potency of the response (EC50 of vasoactive intestinal peptide) was not altered, but the maximal PI hydrolysis response was elevated in the presence of RAMP2 . It has been suggested that this may reflect a change in compartmentalization of the receptor signaling complex. Such augmentation was not evident for the interaction of the VPAC1 receptor with RAMP1 or RAMP3; in these cases, the outcome of heterodimerization may be more subtle or involve the modification of different receptor parameters such as trafficking.

RAMPs transformed our understanding of how receptor pharmacology can be modulated and provided a novel mechanism for generating receptor subtypes within a subset of family B GPCRs. Their role has now broadened and they have been shown to interact with several other family B GPCRs, in 1 case modifying signaling parameters. There is now evidence to suggest that their interactions also reach into family C, and possibly family A, GPCRs, indicating that their function may not be restricted to modulation of a highly specific subset of receptors. Indeed, many aspects of RAMP function remain poorly understood, and the full extent of their action remains to be explored.

Receptor activity modifying proteins

Patrick M. Sexton, Anthony Albiston, Maria Morfis, Nanda Tilakaratne
Cellular Signalling 13 (2001) 73-83  PII: S0898-6568(00)00143-1

Our understanding of G protein-coupled receptor (GPCR) function has recently expanded to encompass novel protein interactions that underlie both cell-surface receptor expression and the exhibited phenotype. The most notable examples are those involving receptor activity modifying proteins (RAMPs). RAMP association with the calcitonin (CT) receptor-like receptor (CRLR) traffics this receptor to the cell surface where individual RAMPs dictate the expression of unique phenotypes. A similar function has been ascribed to RAMP interaction with the CT receptor (CTR) gene product. This review examines
our current state of knowledge of the mechanisms underlying RAMP function.

It is now evident that RAMPs can interact with receptors other than CRLR. Expression of amylin receptor phenotypes requires the coexpression of
RAMPs with the CTR gene product. However, as seen in CRLR, the phenotype engendered by individual RAMPs was distinct. In COS-7 or rabbit aortic endothelial cells (RAECs), RAMP1 and RAMP3 induced amylin receptors that differ in their affinity for CGRP, while RAMP2 was relatively ineffective in inducing amylin receptor phenotype. RAMP2 can also induce an amylin receptor phenotype, which is distinct from either the RAMP1- or RAMP3-induced receptors. However, the efficacy of RAMP2 was highly dependent upon the cellular background and the isoform of CTR used in the study.

In humans, the major CTR variants differ by the presence or absence of a 16 amino acid insert in the first intracellular domain, with the insert negative isoform (hCTRI1ÿ) being the most commonly expressed form and the variant used for initial studies with RAMPs. Unlike hCTRI1ÿ, cotransfection of the hCTRI1+ variant with any of the RAMPs into COS-7 cells caused strong induction of amylin receptor phenotype. The hCTR isoforms differ in their ability to activate signaling pathways (presumably due to an effect on G protein coupling) and to internalize in response to agonist treatment, which may suggest a role for G proteins in the ability of RAMPs to alter receptor phenotype.

There are at least three potential consequences of RAMP interaction with its associating receptors. The first is trafficking of receptor protein from an intracellular compartment to the cell surface. The second is an alteration in
the terminal glycosylation of the receptor, and the third is alteration of receptor phenotype, presumably through a direct or indirect effect on the ligand-binding site.

potential actions of RAMPs

potential actions of RAMPs

Schematic diagram illustrating potential actions of RAMPs. (A) RAMPs facilitate the trafficking of CRLR from an intracellular compartment to the cell surface. (B) RAMP1 (but not RAMP2 or RAMP3) modifies the terminal glycosylation
of CRLR. (C) The cell surface RAMP1±CRLR complex is a Type 1 CGRP receptor, which displays a 1:1 stoichiometry. (D,E) Cell surface RAMP2±CRLR and  RAMP3±CRLR complexes are adrenomedullin receptors. (F,G) For at least RAMP1 and RAMP3, RAMPs form stable homodimers, although the function
of these complexes is unknown. (H) Unlike CRLR, the CTR gene product is trafficked to the cell surface in the absence of RAMPs, where it displays classical CTR phenotype. (I,J) RAMP1± and RAMP3±CTR complexes form distinct amylin receptors. RAMP2 can also generate a separate amylin receptor phenotype (not illustrated). (C ±E,I,J) RAMPs are trafficked with either receptor to the plasma membrane. (K) For all three RAMP±CRLR complexes, agonist treatment causes clathrin-mediated internalization of both CRLR and RAMP.
(L) The majority of the internalized complex is targeted to the lysosomal-degradation pathway.

The data from Zumpe et al. suggest that RAMP2 interacts more weakly with the hCTRI1ÿ than RAMP1, and that the affinity of this interaction derives principally from the transmembrane domain/C-terminus (Ct) of the RAMPs. As RAMP3 induces an amylin receptor phenotype in COS-7 cells where RAMP2 is relatively weak, it is inferred that RAMP3 interaction with the hCTRI1ÿ is probably greater than that of RAMP2. Nonetheless, this has not been examined empirically. Given the recent data suggesting a potential role for G protein coupling in expression of RAMP-induced phenotype, it is also possible that the strength of RAMP interaction is, at least partially, dictated by receptor-G protein or RAMP-G protein interaction.

The discovery of RAMPs has led to a greater understanding of the nature of receptor diversity. However, although much progress has been made into elucidating the molecular mechanism of RAMP action, emerging data continue to open up new areas for investigation. These include identification of other RAMP-interacting receptors, understanding of the role of specific G proteins in RAMP-receptor function and the potential importance of RAMP regulation in disease progression. It also seems likely that the RAMP-receptor interface can provide a useful target for future drug development.

Cardiovascular endothelins: Essential regulators of cardiovascular homeostasis

Friedrich Brunner, C Bras-Silva, AS Cerdeira, AF Leite-Moreira
Pharmacology & Therapeutics 111 (2006) 508 – 531
http://dx.doi.org:/10.1016/j.pharmthera.2005.11.001

The endothelin (ET) system consists of 3 ET isopeptides, several isoforms of activating peptidases, and 2 G-protein-coupled receptors, ETA and ETB, that are linked to multiple signaling pathways. In the cardiovascular system, the components of the ET family are expressed in several tissues, notably the vascular endothelium, smooth muscle cells, and cardiomyocytes. There is general agreement that ETs play important physiological roles in the regulation of normal cardiovascular function, and excessive generation of ET isopeptides has been linked to major cardiovascular pathologies, including hypertension and heart failure. However, several recent clinical trials with ET receptor antagonists were disappointing.

In the present review, the authors take the stance that ETs are mainly and foremost essential regulators of cardiovascular function, hence that antagonizing normal ET actions, even in patients, will potentially do more harm than good. To support this notion, we describe the predominant roles of ETs in blood vessels, which are (indirect) vasodilatation and ET clearance from plasma and interstitial spaces, against the background of the subcellular mechanisms mediating these effects. Furthermore, important roles of ETs in regulating and adapting heart functions to different needs are addressed, including recent progress in understanding the effects of ETs on diastolic function, adaptations to changes in preload, and the interactions between endocardial-derived ET-1 and myocardial pump function. Finally, the potential dangers (and gains) resulting from the suppression of excessive generation or activity of ETs occurring in some cardiovascular pathological states, such as hypertension, myocardial ischemia, and heart failure, are discussed.

Figure (not shown):  Synthesis of ET and its regulation. The release of active ET-1 is controlled via regulation of gene transcription and/or endothelin converting enzyme activity. ET-1 synthesis is stimulated by several factors, of which hypoxia seems to be the most potent in humans (see text). ET-1 formation is down-regulated by activators of the NO/cGMP pathway and other factors.

Figure (not shown): Vascular actions of ET. In healthy blood vessels, the main action of ET-1 is indirect vasodilatation mediated by ETB receptors located on endothelial cells. Their activation generates a Ca2+ signal via PLC that turns on the generation of NO, prostacyclin, adrenomedullin, and other mediators that are powerful relaxants of smooth muscle. On the other hand, binding of ET-1 to ETA receptors located on smooth muscle cells will lead to vascular contraction (physiological effect) and/or wall thickening, inflammation, and tissue remodeling (pathological effects). These latter effects may partly be mediated by vascular ETB2 receptors in certain disease states. Smooth muscle cell signaling involves DAG formation, PKC activation, and extracellular Ca2+ recruited via different cation channels. The specificity of the cellular response resides at the level of G proteins, that is, G-as or G-aq in the case of ETA, G-ai or G-aq for ETB.

signal transduction mechanisms involved in ET-1-mediated positive (left) and negative (right) inotropic effects

signal transduction mechanisms involved in ET-1-mediated positive (left) and negative (right) inotropic effects

Summary of proposed signal transduction mechanisms involved in ET-1-mediated positive (left) and negative (right) inotropic effects. Left: Stimulation of ETA receptors causes Gq protein-directed activation of PLC, formation of IP3 and DAG, and activation of NHE-1. Increased contractile force is the result of (i) Ca2+ release from the sarco(endo)plasmic reticulum, (ii) sensitization of cardiac myofilaments to Ca2+ due to cellular alkalosis, and (iii) increased Ca2+ influx through the NCX operating in reverse mode. The contribution of voltage-gated L-type Ca2+ channels to the systolic Ca2+ transient is unknown, as is the role of myocyte ETB2 receptors. Right: The ET receptor subtypes mediating negative inotropic effects are poorly known. Two main signaling mechanisms involve (i) inhibition of adenylyl cyclase (AC), guided by a G protein, of unknown binding preference, which results in decreased levels of cAMP; (ii) cGMP-mediated activation of phosphatases that dephosphorylate putative targets resulting from cAMP/protein kinase A (PKA) activation. Other kinases like PKC and PKG have also been implicated in accentuated force antagonism.

Adrenomedullin (11–26): a novel endogenous hypertensive peptide isolated from bovine adrenal medulla

Kazuo Kitamuraa,*, Eizaburo Matsuia, Jhoji Katoa, Fumi Katoha
Peptides 22 (2001) 1713–1718 PII: S0196-9781(01)00529-0

Adrenomedullin (AM) is a potent hypotensive peptide originally isolated from pheochromocytoma tissue. Both the ring structure and the C-terminal amide structure of AM are essential for its hypotensive activity. We have developed an RIA which recognizes the ring structure of human AM. Using this RIA, we have characterized the molecular form of AM in bovine adrenal medulla. Gel filtration chromatography revealed that three major peaks of immunoreactive AM existed in the adrenal medulla. The peptide corresponding to Mr 1500 Da was further purified to homogeneity. The peptide was determined to be AM (11–26) which has one intramolecular disulfide bond. Amino acid sequences of bovine AM and its precursor were deduced from the analyses of cDNA encoding bovine AM precursor. The synthetic AM (11–26) produced dose-dependent strong pressor responses in unanesthetized rats in vivo. The hypertensive activity lasted about one minute, and a dose dependent increase in heart rate was also observed. The present data indicate that AM (11–26) is a major component of immunoreactive AM in bovine adrenal medulla and shows pressor activity.

The pressor effect of AM(11–26) was examined by methods similar to those reported for Neuropeptide Y.

We have established a sensitive RIA system using a monoclonal antibody which recognizes the ring structure of human AM. Human AM antiserum recognized the peptide with high affinity at a final dilution of 1:2,800,000. The half maximal inhibition of radioiodinated ligand binding by human AM was observed at 10 fmol/tube. From 1 to 128 fmol/tube of AM was measurable by this RIA system. The intra- and inter-assay coefficients of variance were less than 6% and 9%, respectively. This RIA had 100% cross-reactivity with human AM(13–31), (1–25), (1–52)Gly and AM(1–52)CONH2, but less than 1% cross-reactivity with rat AM.

Sephadex G-50 gel-filtration of strongly basic peptide extract (SP-III) in bovine adrenal medulla identified three major peaks of immunoreactive AM. One emerged at the identical position of authentic AM, the other two unknown peaks were eluted later at molecular weights estimated to be 3000 and 1500 Da, respectively. The peptide corresponding to Mr 1500 Da was further purified.

The purified peptide (20 pmol) was subjected to a gas phase sequencer, and the amino acid sequence was determined up to the 16th residue, which was found to be C terminus . It was found that the purified peptide was AM (11–26). The structure of AM (11–26) was confirmed by chromatographic comparison with native AM (11–26) as well as a synthetic AM (11–26), which has one intramolecular disulfide bond.

3 clones were isolated, and the clone designated pBAM-2, which harbored the longest insert of 1,438 base, was used for sequencing. The bovine AM cDNA contained a single open reading frame encoding a putative 188 amino acid polypeptide. The first 21-residue peptide is thought to be a signal peptide. The bovine AM propeptide contains three signals of dibasic amino acid sequences, Lys-Arg or Arg-Arg. The first Lys-Arg followed proadrenomedullin N-terminal 20 peptide (PAMP) sequences. AM is located between the second signal of Lys-Arg and the third signal of Arg-Arg. Gly residues, which are donors of C-terminal amide structure of PAMP and AM, are found before the first and third signal of Lys-Arg and Arg-Arg. Bovine AM consists of 52 amino acids and is identical to human AM with exception of four amino acids. Bovine PAMP consists of 20 amino acids and is identical to human PAMP with exception of one amino acid. The present cDNA sequence encoding bovine AM precursor is almost identical to those of the reported AM cDNA sequences from bovine aortic endothelial cells. However, a difference in one amino acid was found in the sequences of signal peptide. In addition, three different residues of nucleotides were found in the noncoding region of cDNA encoding bovine preproadreno-medullin.

AM(11–26) elicited a potent hypertensive effects in unanesthetized rats.
When AM(11–26) at 20 nmol/kg was injected i.v., the maximum increase of mean blood pressure was 50  7.1 mmHg. Similarly, the synthetic AM(11–26) produced dose-dependent strong pressor responses in unanesthetized rats in vivo. (Blood pressure increase; F(3, 20 = 13.845, P < 0.0001). Injection of saline did not affects blood pressure and heart rate. The hypertensive activity lasted about 70 s, and a dose dependent increase of heart rate was also observed (Heart rate increase; F(3, 20) = 6.151, P = 0.0039).

We have isolated and characterized bovine AM(11–26) from bovine adrenal medulla as an endogenous peptide. The hallmark biological effects of AM are vasodilation and hypotensive effects in the vascular systems of most species. The mature form of AM has one ring structure formed by an intramolecular disulfide bond and a C terminal amide structure, both of which are essential for the hypotensive and other biological activities of AM. Watanabe et al. reported that the synthetic N-terminal fragment of human AM, AM (1–25)COOH and other related peptides, show vasopressor activity in anesthetized rats. The present purification and characterization of AM(11–26) indicate that the ring structure of AM may function as a biologically active endogenous peptide. The peptide corresponding to Mr 1,500 Da was further purified to homogeneity.

The purified peptide was found to be AM(11–26) which has one intramolecular disulfide bond. The structure of AM(11–26) was confirmed by chromatographic comparison with native AM(11–26) as well as a synthetic specimen which was prepared according to the determined sequence. The structure of bovine AM and related peptides were determined by cDNA analysis encoding bovine AM. Bovine AM consists of 52 amino acids whose sequence is identical to the human sequences with the exception of four amino acids. Furthermore, according to the cDNA analysis and chromatographic comparison of the synthetic AM(11–26) and purified AM, is now determined to be cystine. It should be noted that the structure of bovine AM(11–26) is identical to human AM(11–26).

It is well known that many peptide hormones and neuropeptides are processed from larger, biologically inactive precursors by the specific processing enzyme. It usually recognizes pairs of basic amino acids, processing signals, such as primarily Lys-Arg and Arg-Arg. AM (11–26) is not flanked by such a processing signal, but it was reproducibly observed in bovine adrenal medulla peptide extract. The molar ratio of AM(11–26)/AM was estimated to be 40%. The ratio varied from 5% to 50% according to the individual specimen, but the minor peak corresponding to 1,500 Da was reproducibly observed, suggesting that AM(11–26) is an endogenous peptide. It is likely that AM(11–26) is biosynthesized from AM or AM precursor by a specific enzyme.

In contrast to AM, synthetic bovine AM(11–26) caused potent hypertensive effects in unanesthetized rats. The hypertensive activity of AM(11–26) seems to be comparable to that of AM(1–25) as reported by Watanabe et al.  It was unexpected that AM(11–26) would cause a dose dependent increase of heart rate in unanesthetized rats because vasopressor activity normally causes bradycardia through baroreceptor activation. The hypertensive mechanism is not fully understood, but it has been reported that the vasopressor effect of AM(1–25) might be caused by the release of endogenous catecholamine. We speculate that the released catecholamine counters the baroreceptor function resulting in an increased heart rate and blood pressure. It is possible that AM(11–26) participates in blood pressure control as an endogenous peptide.

A review of the biological properties and clinical implications of adrenomedullin and proadrenomedullin N-terminal 20 peptide (PAMP), hypotensive and vasodilating peptides.

Tanenao Eto
Peptides 22 (2001) 1693–1711 PII: S0196-9781(01)00513-7

Adrenomedullin (AM), identified from pheochromocytoma and having 52 amino acids, elicits a long-lasting vasodilatation and diuresis. AM is mainly mediated by the intracellular adenylate cyclase coupled with cyclic adenosine monophosphate (cAMP) and nitric oxide (NO) -cyclic guanosine monophosphate (cGMP) pathway through its specific receptor. The calcitonin receptor-like receptor (CLCR) and receptor-activity modifying protein (RAMP) 2 or RAMP3 models have been proposed as the candidate receptor. AM is produced mainly in cardiovascular tissues in response to stimuli such as shear stress and stretch, hormonal factors and cytokines. Recently established AM knockout mice lines revealed that AM is essential for development of vitelline vessels of embryo. Plasma AM levels elevate in cardiovascular diseases such as heart failure, hypertension and septic shock, where AM may play protective roles through its characteristic biological activities. Human AM gene delivery improves hypertension, renal function, cardiac hypertrophy and nephrosclerosis in the hypertensive rats. AM decreases cardiac preload and afterload and improves cardiac contractility and diuresis in patients with heart failure and hypertension. Advances in gene engineering and receptor studies may contribute to further understandings of biological implication and therapeutic availability of AM.

AM acts as a circulating hormone as well as elicits multiple biological activities in a paracrine or autocrine manner. Among them the most characteristic biological activity of AM is a very powerful hypotensive activity caused by dilatation of resistance vessels. A sensitive and specific radioimmunoassay demonstrated that AM circulates in blood and occurs in a variety of tissues. Plasma AM levels elevate in various diseases including cardiovascular and renal disorders or septic shock. Thus, AM may be involved in pathophysiological processes in these diseases, especially in disorders controlling circulation and body fluid. In this short review, the history of AM and proadrenomedullin N-terminal 20 peptide (PAMP) will be reviewed with special references to biological properties and function, receptors, gene engineering and clinical viewpoints. This review includes oral presentations from the aforementioned symposium; some of which have not yet been published. These unpublished oral presentations are quoted in this paper from the abstracts of this symposium.

Preproadrenomedullin, which consists of 185 amino acids and contains a 21-amino acid signal peptide, is processed to synthesize proadrenomedullin and finally AM. In the proadrenomedullin, a unique twenty amino acid sequence followed by a typical amidation signal known as Gly-Lys-Arg, is included in the N-terminal region. This novel 20 residues peptide with carboxyl terminus of Arg-CONH2 is also present in vivo and is termed “proadrenomedullin N-terminal 20 peptide (PAMP).” PAMP elicits a potent hypotensive activity in anesthetized rats.

Although widely distributed in the adenophypophysis and the neural lobe of pituitary glands, AM and PAMP occur in cell-specific, but not overlapping, patterns in the anterior pituitary. This cell-specific expression of each peptide may be explained by differences in posttranslational processing of AM gene. As such, potential pituitary specific transcription factor binding sites, gonadotropic-specific element (GSE) and a binding site for steroidogenic factor-l (SF-1) are found in the 5flanking region of human and mouse AM gene.  SF-1 is a member of the steroid receptor superfamily that has been shown necessary for gonadotrope differentiation within the pituitary. In addition, one putative binding sequence of Pit-1 has been reported in mouse AM gene promoter position.

A specific AM binding protein (AMBP-1) in human plasma was isolated and the purified protein was identified as human complement factor H. AM and factor H interaction may interfere with the radioimmunoassay quantification of circulating AM. Factor H enhances AM-mediated induction of cAMP in fibroblast; augments the AM-mediated growth of a cancer cell line; and suppresses the bactericidal capability of AM on Escherichia coli. Conversely, AM influences the complement regulatory function of factor H by enhancing the cleavage of C3b via factor I. The augmentation of AM actions indicates that AMBP may facilitate the binding of AM to its receptor. In addition, the existence of AMBP suggests that large amounts of AM may circulate bound to this plasma protein.

In rat vascular smooth muscle cells, the CGRP, CGRP1 receptor antagonist, competitively inhibits the intracellular accumulation of cAMP induced by AM. Vasodilation of the rat mesenteric vascular bed elicited by AM and CGRP is also blocked by CGRP. Similar effects of CGRP are observed in the isolated rat heart and its microvasculature. Thus, CGRP1 receptor can mediate some effects of AM, but AM has a low affinity at CGRP2 receptor. Two distinct AM labeled bands with a molecular weight of 120 and 70 kDa was reported in the cultured rat vascular smooth muscle cell membrane. Therefore, the binding specificity and characteristics of the AM receptor may differ regionally by organ or tissue.

Two more RAMP proteins, RAMP2 and RAMP3, were discovered from database searches. These proteins share approximately 30% homology with RAMP1. Co-expression of RAMP2 or RAMP3 with CRLR appears to constitute AM receptor. RAMP2 and RAMP3 are indistinguishable in terms of AM binding. The RAMPs are required to transport CRLR to the plasma membrane. RAMP1 presents CRLR as a mature glycoprotein at the cell surface to form a CGRP receptor. However, receptors transported by RAMP2 or RAMP3 are core glycosylated and then become AM receptors. Three putative N-glycosylation sites Asn 60, Asn 112 and Asn 117 are present in the amino-terminal extracellular domain of the human CRLR. When the glycosylation of a myc-tagged CRLR was inhibited, specific 125I-CGRP and -AM binding were blocked in parallel. Substitution of the Asn 117 by threonine abolished CGRP and AM binding in the face of intact N-glycosylation and cell surface expression. RAMPs are accessory proteins of CTR and CRLR at the cell surface where they define AM, amylin, calcitonin and CGRP specificity.

The receptor component protein (RCP) was cloned on the basis of its ability to potentiate the endogenous Xenopus oocyte CGRP receptor. RCP is a cytosolic protein with no similarity to RAMPs, consists of a hydrophobic 146 amino acids and is obtained from the Corti organ of guinea pig. RCF plays an essential role for signal-transduction of CGRP and AM, and interacts with CRLR directly within the cells. Thus, a functional AM or CGRP receptor seems to consist of at least three proteins: CRLR, RAMP and RCP, coupling the receptor to the intracellular signal-transduction pathway.

By using a chimera of the CRLR and green fluorescent protein (GFP), the study demonstrated that CRLR-GFP failed to generate responses to CGRP or AM without RAMP2 or RAMP3 in HEK 293 cells. When coexpressed with RAMP2 or RAMP3, CRLR-GFP appeared on the cell membrane and activated an intracellular cAMP production and calcium mobilization. Agonist-mediated internalization of CRLR-GFP was observed in RAMP1/CGRP or AM, RAMP2/AM, and RAMP3/AM, which occurred with similar kinetics, indicating the existence of ligand-specific regulation of CRLR internalization by RAMPs.

The discovery of RAMPs has promoted our understandingthat some of the biological activities of AM are blocked by CGRP receptor antagonist, whereas other biological activities are blocked only by AM receptor antagonist, which indicates the possible existence of AM receptor in dual nature. RAMP association with CRLR traffics this receptor to the cell surface where individual RAMPs dictate the expression of unique phenotypes such as CGRP receptor or AM receptors. Apart from receptor trafficking and glycosylation, the RAMPs may interact directly with the receptors in the cell surface modifying their affinities for the ligands.

Since AM was discovered by monitoring the elevating activity of cAMP in rat platelets, cAMP appears to be its major second messenger. Dose-dependent intracellular production of cAMP induced by AM has been confirmed in various tissues and cells. Moreover, information on the role of NO in alternative signal-transduction pathways for AM is available.

The vasodilating effect of AM is reduced by the blockade of NO synthetase activity with NG-nitro-L-arginine methylester (L-NAME), indicating that NO may at least partly contribute to the AM-induced vasodilation. However, the degree of NO contribution to vasodilation varies depending upon the organ or tissue and the species. NO synthetase inhibitor in the pulmonary vascular beds of rat significantly attenuates the AM-induced vasodilation, but it does not occur in cats. Thus, NO seems to be an important AM mediator despite regional and interspecies variation.

In bovine aortic endothelial cells, AM increases intracellular ionic calcium (Ca2+) and causes the accumulation of cAMP. This increase in intracellular Ca2+ may be involved in the activation of phospholipase C, thereby producing inducible NO synthetase and subsequently NO. NO transferred to medial smooth muscle cells may activate cGMP-mediating smooth muscle cells vasodilatation. In contrast, AM lowers both cytosolic Ca2+ and Ca2+ sensitivity in smooth muscle cells of pig coronary arteries and intracellular Ca2+ in rat renal arterial smooth muscle cells.

Among the multi-functional properties of AM, the most characteristic one is an intensive, long-lasting hypotension that is dose-dependent in humans, rats, rabbits, dogs, cats and sheep. AM dilates resistance vessels in the kidneys, brain, lung, hindlimbs in animals as well as in the mesentery. Moreover, AM elicits relaxation of ring preparations of the aorta and cerebral arteries. An i.v. injection of human AM to conscious sheep causes a dose dependent fall of blood pressure, an increase in heart rate and cardiac output with a small reduction in stroke volume, as well as a marked decrease in total peripheral resistance. Coronary blood flow increases in parallel with the increase in coronary conductance. These cardiovascular responses return to the control level by 40 min after the injection.

The low-dose infusion of AM administered to conscious sheep on a low-salt diet antagonizes the vasopressor actions of administered angiotensin II while stimulating cardiac output and heart rate. AM may control cardiovascular homeostasis in part through antagonism of the vasopressor action of angiotensin II. AM inhibits the secretion of endothelin-1 from the vascular endothelial cells and proliferation of vascular smooth muscle cells. In the cultured cardiomyocytes as well as cardiac fibroblasts, AM inhibits protein synthesis in these cells in an autocrine or a paracrine manner, which may result in modulating the cardiac growth. AM inhibits bronchial constriction induced by acetylcholine or histamine in a dose-dependent  manner, indicating the important role of AM on airway function and its usefulness for the management of bronchial asthma. AM inhibits secretion of aldosterone from the adrenal cortex. When infused directly into the adrenal arterial supply of conscious sheep, AM directly inhibits the acute stimulation of aldosterone by angiotensin II,  KCl and ACTH while not affecting basal or chronic aldosterone secretion or cortisol secretion stimulated by ACTH. AM co-exists in insulin-producing cells and it inhibits insulin secretion dose-dependently in isolated rat islets.

The N-terminal region of preproadrenomedullin, the precursor of AM, contains a unique 20-residue sequence followed by Gly-Lys-Arg, a typical amidation signal, which was termed as proadrenomedullin N-terminal 20 peptide (PAMP). PAMP was purified from porcine adrenal medulla and human pheochromo-cytoma by using radioimmunoassay for the peptide and its complete amino acid sequence was determined. In addition to the original form of PAMP [1–20], PAMP [9–20] has recently been purified from the bovine adrenal medulla. The amino acid sequences of both forms of PAMP are identical to amino acid sequences deduced by cDNA analysis and their carboxyl terminus of Arg is amidated. The distribution of PAMP is similar to that of human AM, due to the fact that PAMP as well as human AM is biosynthesized from an AM precursor.

AM is processed from its precursor, proadrenomedullin, as the intermediate or immature form, AM-glycine (AM[1–52]-COOH, immature AM). Subsequently, immature AM is converted to the biologically active mature form, AM [1–52]-CONH2 (mature AM) by enzymatic amidation. The AM circulating in the human blood stream (total AM), thus, consists of both mature AM and immature AM. In earlier studies, plasma AM levels were measured by using radioimmunoassay recognizing the entire AM molecule (AM [1–52]), which reflects plasma total AM levels, as previously described.

In healthy volunteers severe exercise elevates the plasma AM levels with an increase in plasma norepinephrine and exaggerated sympathetic nerve activity. In heart transplant recipients, maximal exercise induces an increase in plasma AM that is inversely related to mean blood pressure. AM, therefore, may participate in blood pressure regulation during exercise even after heart transplantation.

When compared with healthy controls, the plasma AM levels are increased in patients with a variety of diseases: congestive heart failure, myocardial infarction, renal diseases, hypertensive diseases, diabetes mellitus, acute phase of stroke, and septic shock.

Adrenomedullin and central cardiovascular regulation

Meghan M. Taylor, Willis K. Samson
Peptides 22 (2001) 1803–1807 PII: S0196-9781(01)00522-8

Adrenomedullin gene products have been localized to neurons in brain that innervate sites known to be important in the regulation of cardiovascular function. Those sites also have been demonstrated to possess receptors for the peptide and central administrations of adrenomedullin (AM) and proadrenomedullin N-terminal 20 peptide (PAMP) elevate blood pressure and heart rate in both conscious and anesthetized animals. The accumulated evidence points to a role of the sympathetic nervous system in these cardiovascular effects. These sympathostimulatory actions of AM and PAMP have been hypothesized to be cardioprotective in nature and to reflect the central nervous system (CNS) equivalent of the direct cardiostimulatory effects of the peptides in the periphery. This review summarizes the most recent data on the CNS actions of the adrenomedullin gene-derived peptides and suggests future strategies for the elucidation of the physiologic relevance of the already demonstrated, pharmacologic actions of these peptides.

Adrenomedullin and related peptides: receptors and accessory proteins

Roman Muff, Walter Born, Jan A. Fischer
Peptides 22 (2001) 1765–1772  PII: S0196-9781(01)00515-0
Adrenomedullin (AM), α- and β-calcitonin gene-related peptide (CGRP), amylin and calcitonin (CT) are structurally and functionally related peptides. The structure of a receptor for CT (CTR) was elucidated in 1991 through molecular cloning, but the structures of the receptors for the other three peptides had yet to be elucidated. The discovery of receptor-activity-modifying proteins (RAMP) 1 and -2 and their co-expression with an orphan receptor, calcitonin receptor-like receptor (CRLR) has led to the elucidation of functional CGRP and AM receptors, respectively. RAMP1 and -3 which are co-expressed with CTR revealed two amylin receptor isotypes. Molecular interactions between CRLR and RAMPs are involved in their transport to the cell surface. Heterodimeric complexes between CRLR or CTR and RAMPs are required for ligand recognition.

Pharmacological profiles of receptors of the adrenomedullin peptidefamily
AMR AM>CGRP>>amylin=CT
CTR CT>amylin>>CGRP=AM
CGRPR CGRP>AM>>amylin=CT
AmylinR AmylinsCT­CGRP>>hCT>AM

Specific AM binding sites have been identified in many tissues including the heart, blood vessels, lung and spleen. Based on pharmacological evidence two receptor isotypes have been distinguished, for instance in rat astrocytes and NG108–15 cells. One AM receptor isotype recognizes CGRP and CGRP(8–37). The other receptor isotype specific for the AM ligand and antagonized by AM(22–52) does not recognize CGRP to any great extent. Both isotypes of the receptors have been shown to interact poorly with amylin and CT (Table). Biological actions of AM include vaso- and bronchodilation, and CNS transmitted inhibition of water intake.

CGRP receptors are widely distributed in the nervous and cardiovascular systems. To date, two isotypes have been described. On pharmacological evidence, CGRP1 receptors, such as those identified in human SK-N-MC neuroblastoma cells, recognize intact CGRP and CGRP(8–37) with similar potency, unlike a linear analog lacking the disulfide bridge. CGRP2 receptors,
on the other hand, interact with the linear analog but not with CGRP(8–37). These CGRP receptor isotypes cross-react with AM to some extent, but only minimally with amylin and CT. CGRP shares potent vasodilatory actions with AM, and has chronotropic and inotropic actions in the heart. The ionotropic actions are indirectly brought about via activation of the sympathetic nervous system. There is evidence to suggest the existence of α- or β-CGRP preferring receptor isotypes in both the central nervous system and peripheral tissues.

RAMP1, -2 and -3 are widely expressed, suggesting that RAMPs may have
important functions beyond those of the adrenomedullin family of receptors. To this end, RAMP1 and -3 are thought to reduce cell surface expression of angiotensin (AT) AT1 and AT2 receptors.

RAMP2 and CRLR are expressed in vascular smooth muscle cells, and RAMP1 expression was increased by dexamethasone. Moreover, increased levels of RAMP2 and CRLR were observed in the kidney and heart of rats with obstructive nephropathy and congestive heart failure, respectively. RAMP2
and CRLR levels were reduced, and RAMP3 levels were increased during lipopolysaccharide induced sepsis in rats.

The GABAB receptor 1 is retained as an immature glycoprotein in the cytosol unless co-expressed with GABAB receptor 2 isotype. Heterodimers of fully functional opioid receptors δ and κ result in a novel receptor displaying binding and functional properties distinct from those of the δ or κ receptors alone. Heterodimerization therefore facilitates receptor expression and defines ligand specificity also in G protein-coupled receptor families A and C. Moreover, heterodimers of metabotropic glutamate 1receptor (family C) and adenosine A1 receptors (family A) have been observed. As yet there is no evidence for homo or heterodimerization of family B receptors. Cysteines conserved in the extracellular N-terminal domain in all the receptors of family B and RAMPs suggest that RAMPs are truncated forms of receptors that interact as heterodimers with CRLR and CTR.

The discovery of RAMPs in combination with CRLR and CTR has led to the molecular identification of CGRP1, CGRP/amylin, AM and amylin receptor complexes. The physiological advantage of heterodimers between seven transmembrane domain receptors and the RAMPs required for the functional expression of the adrenomedullin, CGRP and amylin receptors remains to be demonstrated.

Angiotensin II, From Vasoconstrictor to Growth Factor: A Paradigm Shift

Sasa Vukelic, Kathy K. Griendling
Circ Res. 2014;114:754-757
http://dx.doi.org:/10.1161/CIRCRESAHA.114.303045

Angiotensin II (Ang II) is today considered as one of the essential factors in the pathophysiology of cardiovascular disease, producing acute hemodynamic and chronic pleiotropic effects. Although now it is widely accepted that these chronic effects are important, Ang II was initially considered only a short-acting, vasoactive hormone. This view was modified a quarter of a century ago when Dr Owens and his group published an article in Circulation Research with initial evidence that Ang II can act as a growth factor that regulates cell hypertrophy. They showed in a series of elegant experiments that Ang II promotes hypertrophy and hyperploidy of cultured rat aortic smooth muscle cells. However, Ang II had no effect on hyperplasia. These findings led to a paradigm shift in our understanding of the roles of growth factors and vasoactive substances in cardiovascular pathology and helped to redirect basic and clinical renin–angiotensin system research during the next 25 years. Ang II is now known to be a pleiotropic hormone that uses multiple signaling pathways to influence most processes that contribute to the development and progression of cardiovascular diseases, ranging from hypertrophy, endothelial dysfunction, cardiac remodeling, fibrosis, and inflammation to oxidative stress.

Read Full Post »


Summary of Proteomics

Author and Curator: Larry H. Bernstein, MD, FCAP 

 

We have completed a series of discussions on proteomics, a scientific endeavor that is essentially 15 years old.   It is quite remarkable what has been accomplished in that time.  The interest is abetted by the understanding of the limitations of the genomic venture that has preceded it.  The thorough, yet incomplete knowledge of the genome, has led to the clarification of its limits.  It is the coding for all that lives, but all that lives has evolved to meet a demanding and changing environment with respect to

  1. availability of nutrients
  2. salinity
  3. temperature
  4. radiation exposure
  5. toxicities in the air, water, and food
  6. stresses – both internal and external

We have seen how both transcription and translation of the code results in a protein, lipoprotein, or other complex than the initial transcript that was modeled from tRNA. What you see in the DNA is not what you get in the functioning cell, organ, or organism.  There are comparabilities as well as significant differences between plants, prokaryotes, and eukaryotes.  There is extensive variation.  The variation goes beyond genomic expression, and includes the functioning cell, organ type, and species.

Here, I return to the introductory discussion.  Proteomics is a goal directed, sophisticated science that uses a combination of methods to find the answers to biological questions. Graves PR and Haystead TAJ.  Molecular Biologist’s Guide to Proteomics.
Microbiol Mol Biol Rev. Mar 2002; 66(1): 39–63.  http://www.ncbi.nlm.nih.gov/pmc/articles/PMC120780/

Peptide mass tag searching

Peptide mass tag searching

Peptide mass tag searching. Shown is a schematic of how information from an unknown peptide (top) is matched to a peptide sequence in a database (bottom) for protein identification. The partial amino acid sequence or “tag” obtained by MS/MS is combined with the peptide mass (parent mass), the mass of the peptide at the start of the sequence (mass tag 1), and the mass of the peptide at the end of the sequence (mass tag 2). The specificity of the protease used (trypsin is shown) can also be included in the search.

ICAT method for measuring differential protein expression

ICAT method for measuring differential protein expression

The ICAT method for measuring differential protein expression. (A) Structure of the ICAT reagent. ICAT consists of a biotin affinity group, a linker region that can incorporate heavy (deuterium) or light (hydrogen) atoms, and a thiol-reactive end group for linkage to cysteines. (B) ICAT strategy. Proteins are harvested from two different cell states and labeled on cysteine residues with either the light or heavy form of the ICAT reagent. Following labeling, the two protein samples are mixed and digested with a protease such as trypsin. Peptides labeled with the ICAT reagent can be purified by virtue of the biotin tag by using avidin chromatography. Following purification, ICAT-labeled peptides can be analyzed by MS to quantitate the peak ratios and proteins can be identified by sequencing the peptides with MS/MS.

Strategies for determination of phosphorylation sites in proteins

Strategies for determination of phosphorylation sites in proteins

Strategies for determination of phosphorylation sites in proteins. Proteins phosphorylated in vitro or in vivo can be isolated by protein electrophoresis and analyzed by MS. (A) Identification of phosphopeptides by peptide mass fingerprinting. In this method, phosphopeptides are identified by comparing the mass spectrum of an untreated sample to that of a sample treated with phosphatase. In the phosphatase-treated sample, potential phosphopeptides are identified by a decrease in mass due to loss of a phosphate group (80 Da). (B) Phosphorylation sites can be identified by peptide sequencing using MS/MS. (C) Edman degradation can be used to monitor the release of inorganic 32P to provide information about phosphorylation sites in peptides.

protein mining strategy

protein mining strategy

Proteome-mining strategy. Proteins are isolated on affinity column arrays from a cell line, organ, or animal source and purified to remove nonspecific adherents. Then, compound libraries are passed over the array and the proteins eluted are analyzed by protein electrophoresis. Protein information obtained by MS or Edman degradation is then used to search DNA and protein databases. If a relevant target is identified, a sublibrary of compounds can be evaluated to refine the lead. From this method a protein target and a drug lead can be simultaneously identified.

Although the technology for the analysis of proteins is rapidly progressing, it is still not feasible to study proteins on a scale equivalent to that of the nucleic acids. Most of proteomics relies on methods, such as protein purification or PAGE, that are not high-throughput methods. Even performing MS can require considerable time in either data acquisition or analysis. Although hundreds of proteins can be analyzed quickly and in an automated fashion by a MALDI-TOF mass spectrometer, the quality of data is sacrificed and many proteins cannot be identified. Much higher quality data can be obtained for protein identification by MS/MS, but this method requires considerable time in data interpretation. In our opinion, new computer algorithms are needed to allow more accurate interpretation of mass spectra without operator intervention. In addition, to access unannotated DNA databases across species, these algorithms should be error tolerant to allow for sequencing errors, polymorphisms, and conservative substitutions. New technologies will have to emerge before protein analysis on a large-scale (such as mapping the human proteome) becomes a reality.

Another major challenge for proteomics is the study of low-abundance proteins. In some eukaryotic cells, the amounts of the most abundant proteins can be 106-fold greater than those of the low-abundance proteins. Many important classes of proteins (that may be important drug targets) such as transcription factors, protein kinases, and regulatory proteins are low-copy proteins. These low-copy proteins will not be observed in the analysis of crude cell lysates without some purification. Therefore, new methods must be devised for subproteome isolation.

Tissue Proteomics for the Next Decade?  Towards a Molecular Dimension in Histology

R Longuespe´e, M Fle´ron, C Pottier, F Quesada-Calvo, Marie-Alice Meuwis, et al.
OMICS A Journal of Integrative Biology 2014; 18: 9.    http://dx.doi.org:/10.1089/omi.2014.0033

The concept of tissues appeared more than 200 years ago, since textures and attendant differences were described within the whole organism components. Instrumental developments in optics and biochemistry subsequently paved the way to transition from classical to molecular histology in order to decipher the molecular contexts associated with physiological or pathological development or function of a tissue. In 1941, Coons and colleagues performed the first systematic integrated examination of classical histology and biochemistry when his team localized pneumonia antigens in infected tissue sections. Most recently, in the early 21st century, mass spectrometry (MS) has progressively become one of the most valuable tools to analyze biomolecular compounds. Currently, sampling methods, biochemical procedures, and MS instrumentations
allow scientists to perform ‘‘in depth’’ analysis of the protein content of any type of tissue of interest. This article reviews the salient issues in proteomics analysis of tissues. We first outline technical and analytical considerations for sampling and biochemical processing of tissues and subsequently the instrumental possibilities for proteomics analysis such as shotgun proteomics in an anatomical context. Specific attention concerns formalin fixed and paraffin embedded (FFPE) tissues that are potential ‘‘gold mines’’ for histopathological investigations. In all, the matrix assisted laser desorption/ionization (MALDI) MS imaging, which allows for differential mapping of hundreds of compounds on a tissue section, is currently the most striking evidence of linkage and transition between ‘‘classical’’ and ‘‘molecular’’ histology. Tissue proteomics represents a veritable field of research and investment activity for modern biomarker discovery and development for the next decade.

Progressively, tissue analyses evolved towards the description of the whole molecular content of a given sample. Currently, mass spectrometry (MS) is the most versatile
analytical tool for protein identification and has proven its great potential for biological and clinical applications. ‘‘Omics’’ fields, and especially proteomics, are of particular
interest since they allow the analysis of a biomolecular picture associated with a given physiological or pathological state. Biochemical techniques were then adapted for an optimal extraction of several biocompounds classes from tissues of different natures.

Laser capture microdissection (LCM) is used to select and isolate tissue areas of interest for further analysis. The developments of MS instrumentations have then definitively transformed the scientific scene, pushing back more and more detection and identification limits. Since a few decades, new approaches of analyses appeared, involving the use of tissue sections dropped on glass slides as starting material. Two types of analyses can then be applied on tissue sections: shotgun proteomics and the very promising MS imaging (MSI) using Matrix Assisted Laser Desorption/Ionization (MALDI) sources. Also known as ‘‘molecular histology,’’ MSI is the most striking hyphen between histology and molecular analysis. In practice, this method allows visualization of the spatial distribution of proteins, peptides, drugs, or others analytes directly on tissue sections. This technique paved new ways of research, especially in the field of histopathology, since this approach appeared to be complementary to conventional histology.

Tissue processing workflows for molecular analyses

Tissue processing workflows for molecular analyses

Tissue processing workflows for molecular analyses. Tissues can either be processed in solution or directly on tissue sections. In solution, processing involves protein
extraction from tissue pieces in order to perform 2D gel separation and identification of proteins, shotgun proteomics, or MALDI analyses. Extracts can also be obtained from
tissues area selection and protein extraction after laser micro dissection or on-tissue processing. Imaging techniques are dedicated to the morphological characterization or molecular mapping of tissue sections. Histology can either be conducted by hematoxylin/eosin staining or by molecular mapping using antibodies with IHC. Finally, mass spectrometry imaging allows the cartography of numerous compounds in a single analysis. This approach is a modern form of ‘‘molecular histology’’ as it grafts, with the use of mathematical calculations, a molecular dimension to classical histology. (AR, antigen retrieval; FFPE, formalin fixed and paraffin embedded; fr/fr, fresh frozen; IHC, immunohistochemistry; LCM, laser capture microdissection; MALDI, matrix assisted laser desorption/ionization; MSI, mass spectrometry imaging; PTM, post translational modification.)

Analysis of tissue proteomes has greatly evolved with separation methods and mass spectrometry instrumentation. The choice of the workflow strongly depends on whether a bottom-up or a top-down analysis has to be performed downstream. In-gel or off-gel proteomics principally differentiates proteomic workflows. The almost simultaneous discoveries of the MS ionization sources (Nobel Prize awarded) MALDI (Hillenkamp and Karas, 1990; Tanaka et al., 1988) and electrospray ionization (ESI) (Fenn et al., 1989) have paved the way for analysis of intact proteins and peptides. Separation methods such as two-dimension electrophoresis (2DE) (Fey and Larsen, 2001) and nanoscale reverse phase liquid chromatography (nanoRP-LC) (Deterding et al., 1991) lead to efficient preparation of proteins for respectively topdown and bottom-up strategies. A huge panel of developments was then achieved mostly for LC-MS based proteomics in order to improve ion fragmentation approaches and peptide
identification throughput relying on database interrogation. Moreover, approaches were developed to analyze post translational modifications (PTM) such as phosphorylations (Ficarro et al., 2002; Oda et al., 2001; Zhou et al., 2001) or glycosylations (Zhang et al., 2003), proposing as well different quantification procedures. Regarding instrumentation, the most cutting edge improvements are the gain of mass accuracy for an optimal detection of the eluted peptides during LC-MS runs (Mann and Kelleher, 2008; Michalski et al., 2011) and the increase in scanning speed, for example with the use of Orbitrap analyzers (Hardman and Makarov, 2003; Makarov et al., 2006; Makarov et al., 2009; Olsen et al., 2009). Ion transfer efficiency was also drastically improved with the conception of ion funnels that homogenize the ion transmission
capacities through m/z ranges (Kelly et al., 2010; Kim et al., 2000; Page et al., 2006; Shaffer et al., 1998) or by performing electrospray ionization within low vacuum (Marginean et al., 2010; Page et al., 2008; Tang et al., 2011). Beside collision induced dissociation (CID) that is proposed for many applications (Li et al., 2009; Wells and McLuckey, 2005), new fragmentation methods were investigated, such as higher-energy collisional dissociation (HCD) especially for phosphoproteomic
applications (Nagaraj et al., 2010), and electron transfer dissociation (ETD) and electron capture dissociation (ECD) that are suited for phospho- and glycoproteomics (An
et al., 2009; Boersema et al., 2009; Wiesner et al., 2008). Methods for data-independent MS2 analysis based on peptide fragmentation in given m/z windows without precursor selection neither information knowledge, also improves identification throughput (Panchaud et al., 2009; Venable et al., 2004), especially with the use of MS instruments with high resolution and high mass accuracy specifications (Panchaud et al., 2011). Gas fractionation methods such as ion mobility (IM) can also be used as a supplementary separation dimension which enable more efficient peptide identifications (Masselon et al., 2000; Shvartsburg et al., 2013; Shvartsburg et al., 2011).

Microdissection relies on a laser ablation principle. The tissue section is dropped on a plastic membrane covering a glass slide. The preparation is then placed into a microscope
equipped with a laser. A highly focused beam will then be guided by the user at the external limit of the area of interest. This area composed by the plastic membrane, and the tissue section will then be ejected from the glass slide and collected into a tube cap for further processing. This mode of microdissection is the most widely used due to its ease of handling and the large panels of devices proposed by constructors. Indeed, Leica microsystem proposed the Leica LMD system (Kolble, 2000), Molecular Machine and Industries, the MMI laser microdissection system Microcut, which was used in combination with IHC (Buckanovich et al., 2006), Applied Biosystems developed the Arcturus
microdissection System, and Carl Zeiss patented P.A.L.M. MicroBeam technology (Braakman et al., 2011; Espina et al., 2006a; Espina et al., 2006b; Liu et al., 2012; Micke
et al., 2005). LCM represents a very adequate link between classical histology and sampling methods for molecular analyses as it is a simple customized microscope. Indeed,
optical lenses of different magnification can be used and the method is compatible with classical IHC (Buckanovich et al., 2006). Only the laser and the tube holder need to be
added to the instrumentation.

After microdissection, the tissue pieces can be processed for analyses using different available MS devices and strategies. The simplest one consists in the direct analysis of the
protein profiles by MALDI-TOF-MS (MALDI-time of flight-MS). The microdissected tissues are dropped on a MALDI target and directly covered by the MALDI matrix (Palmer-Toy et al., 2000; Xu et al., 2002). This approach was already used in order to classify breast cancer tumor types (Sanders et al., 2008), identify intestinal neoplasia protein biomarkers (Xu et al., 2009), and to determine differential profiles in glomerulosclerosis (Xu et al., 2005).

Currently the most common proteomic approach for LCM tissue analysis is LC-MS/MS. Label free LC-MS approaches have been used to study several cancers like head and neck squamous cell carcinomas (Baker et al., 2005), esophageal cancer (Hatakeyama et al., 2006), dysplasic cervical cells (Gu et al., 2007), breast carcinoma tumors (Hill et al., 2011; Johann et al., 2009), tamoxifen-resistant breast cancer cells (Umar et al., 2009), ER + / – breast cancer cells (Rezaul et al., 2010), Barretts esophagus (Stingl et al., 2011), and ovarian endometrioid cancer (Alkhas et al., 2011). Different isotope labeling methods have been used in order to compare proteins expression. ICAT was first used to investigate proteomes of hepatocellular carcinoma (Li et al., 2004; 2008). The O16/O18 isotopic labeling was then used for proteomic analysis of ductal carcinoma of the breast (Zang et al., 2004).

Currently, the lowest amount of collected cells for a relevant single analysis using fr/fr breast cancer tissues was 3000–4000 (Braakman et al., 2012; Liu et al., 2012; Umar et al., 2007). With a Q-Exactive (Thermo, Waltham) mass spectrometer coupled to LC, Braakman was able to identify up to 1800 proteins from 4000 cells. Processing
of FFPE microdissected tissues of limited sizes still remains an issue which is being addressed by our team.

Among direct tissue analyses modes, two categories of investigations can be done. MALDI profiling consists in the study of molecular localization of compounds and can be
combined with parallel shotgun proteomic methods. Imaging methods give less detailed molecular information, but is more focused on the accurate mapping of the detected compounds through tissue area. In 2007, a concept of direct tissue proteomics (DTP) was proposed for high-throughput examination of tissue microarray samples. However, contrary to the classical workflow, tissue section chemical treatment involved a first step of scrapping each FFPE tissue spot with a razor blade from the glass slide. The tissues were then transferred into a tube and processed with RIPA buffer and finally submitted to boiling as an AR step (Hwang et al., 2007). Afterward, several teams proved that it was possible to perform the AR directly on tissue sections. These applications were mainly dedicated to MALDI imaging analyses (Bonnel et al., 2011; Casadonte and Caprioli, 2011; Gustafsson et al., 2010). However, more recently, Longuespe´e used citric acid antigen retrieval (CAAR) before shotgun proteomics associated to global profiling proteomics (Longuespee et al., 2013).

MALDI imaging workflow

MALDI imaging workflow

MALDI imaging workflow. For MALDI imaging experiments, tissue sections are dropped on conductive glass slides. Sample preparations are then adapted depending on the nature of the tissue sample (FFPE or fr/fr). Then, matrix is uniformly deposited on the tissue section using dedicated devices. A laser beam subsequently irradiates the preparation following a given step length and a MALDI spectrum is acquired for each position. Using adapted software, the different detected ions are then mapped through the tissue section, in function of their differential intensities. The ‘‘molecular maps’’ are called images. (FFPE, formalin fixed and paraffin embedded; fr/fr, fresh frozen; MALDI, matrix assisted laser desorption ionization.)

Proteomics instrumentations, specific biochemical preparations, and sampling methods such as LCM altogether allow for the deep exploration and comparison of different proteomes between regions of interest in tissues with up to 104 detected proteins. MALDI MS imaging that allows for differential mapping of hundreds of compounds on a tissue section is currently the most striking illustration of association between ‘‘classical’’ and ‘‘molecular’’ histology.

Novel serum protein biomarker panel revealed by mass spectrometry and its prognostic value in breast cancer

L Chung, K Moore, L Phillips, FM Boyle, DJ Marsh and RC Baxter*  Breast Cancer Research 2014, 16:R63
http://breast-cancer-research.com/content/16/3/R63

Introduction: Serum profiling using proteomic techniques has great potential to detect biomarkers that might improve diagnosis and predict outcome for breast cancer patients (BC). This study used surface-enhanced laser desorption/ionization time-of-flight (SELDI-TOF) mass spectrometry (MS) to identify differentially expressed proteins in sera from BC and healthy volunteers (HV), with the goal of developing a new prognostic biomarker panel.
Methods: Training set serum samples from 99 BC and 51 HV subjects were applied to four adsorptive chip surfaces (anion-exchange, cation-exchange, hydrophobic, and metal affinity) and analyzed by time-of-flight MS. For validation, 100 independent BC serum samples and 70 HV samples were analyzed similarly. Cluster analysis of protein spectra was performed to identify protein patterns related to BC and HV groups. Univariate and multivariate statistical analyses were used to develop a protein panel to distinguish breast cancer sera from healthy sera, and its prognostic potential was evaluated.
Results: From 51 protein peaks that were significantly up- or downregulated in BC patients by univariate analysis, binary logistic regression yielded five protein peaks that together classified BC and HV with a receiver operating characteristic (ROC) area-under-the-curve value of 0.961. Validation on an independent patient cohort confirmed
the five-protein parameter (ROC value 0.939). The five-protein parameter showed positive association with large tumor size (P = 0.018) and lymph node involvement (P = 0.016). By matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) MS, immunoprecipitation and western blotting the proteins were identified as a fragment
of apolipoprotein H (ApoH), ApoCI, complement C3a, transthyretin, and ApoAI. Kaplan-Meier analysis on 181 subjects after median follow-up of >5 years demonstrated that the panel significantly predicted disease-free survival (P = 0.005), its efficacy apparently greater in women with estrogen receptor (ER)-negative tumors (n = 50, P = 0.003) compared to ER-positive (n = 131, P = 0.161), although the influence of ER status needs to be confirmed after longer follow-up.
Conclusions: Protein mass profiling by MS has revealed five serum proteins which, in combination, can distinguish between serum from women with breast cancer and healthy control subjects with high sensitivity and specificity. The five-protein panel significantly predicts recurrence-free survival in women with ER-negative tumors and may have value in the management of these patients.

Cellular prion protein is required for neuritogenesis: fine-tuning of multiple signaling pathways involved in focal adhesions and actin cytoskeleton dynamics

Aurélie Alleaume-Butaux, et al.   Cell Health and Cytoskeleton 2013:5 1–12

Neuritogenesis is a dynamic phenomenon associated with neuronal differentiation that allows a rather spherical neuronal stem cell to develop dendrites and axon, a prerequisite for the integration and transmission of signals. The acquisition of neuronal polarity occurs in three steps:

(1) neurite sprouting, which consists of the formation of buds emerging from the postmitotic neuronal soma;

(2) neurite outgrowth, which represents the conversion of buds into neurites, their elongation and evolution into axon or dendrites; and

(3) the stability and plasticity of neuronal polarity.

In neuronal stem cells, remodeling and activation of focal adhesions (FAs)

  • associated with deep modifications of the actin cytoskeleton is
  • a prerequisite for neurite sprouting and subsequent neurite outgrowth.

A multiple set of growth factors and interactors located in

  • the extracellular matrix and the plasma membrane orchestrate neuritogenesis
  • by acting on intracellular signaling effectors, notably small G proteins such as RhoA, Rac, and Cdc42,
  • which are involved in actin turnover and the dynamics of FAs.

The cellular prion protein (PrPC), a glycosylphosphatidylinositol (GPI)-anchored membrane protein

  • mainly known for its role in a group of fatal neurodegenerative diseases,
  • has emerged as a central player in neuritogenesis.

Here, we review the contribution of PrPC to neuronal polarization and

  • detail the current knowledge on the signaling pathways fine-tuned
  • by PrPC to promote neurite sprouting, outgrowth, and maintenance.

We emphasize that PrPC-dependent neurite sprouting is a process in which

  • PrPC governs the dynamics of FAs and the actin cytoskeleton via β1 integrin signaling.

The presence of PrPC is necessary to render neuronal stem cells

  • competent to respond to neuronal inducers and to develop neurites.

In differentiating neurons, PrPC exerts a facilitator role towards neurite elongation.

This function relies on the interaction of PrPC with a set of diverse partners such as

  1. elements of the extracellular matrix,
  2. plasma membrane receptors,
  3. adhesion molecules, and
  4. soluble factors that control actin cytoskeleton turnover
  • through Rho-GTPase signaling.

Once neurons have reached their terminal stage of differentiation and

  • acquired their polarized morphology,
  • PrPC also takes part in the maintenance of neurites.

By acting on tissue nonspecific alkaline phosphatase, or matrix metalloproteinase type 9,

  • PrPC stabilizes interactions between neurites and the extracellular matrix.

Fusion-pore expansion during syncytium formation is restricted by an actin network

Andrew Chen et al., Journal of Cell Science 121, 3619-3628. http://dx.doi.org:/10.1242/jcs.032169

Cell-cell fusion in animal development and in pathophysiology

  • involves expansion of nascent fusion pores formed by protein fusogens
  • to yield an open lumen of cell-size diameter.

Here we explored the enlargement of micron-scale pores in syncytium formation,

  • which was initiated by a well-characterized fusogen baculovirus gp64.

Radial expansion of a single or, more often, of multiple fusion pores

  • proceeds without loss of membrane material in the tight contact zone.

Pore growth requires cell metabolism and is

  • accompanied by a local disassembly of the actin cortex under the pores.

Effects of actin-modifying agents indicate that

  • the actin cortex slows down pore expansion.

We propose that the growth of the strongly bent fusion-pore rim

  1. is restricted by a dynamic resistance of the actin network and
  2. driven by membrane-bending proteins that are involved in
  3. the generation of highly curved intracellular membrane compartments.

Pak1 Is Required to Maintain Ventricular Ca2+ Homeostasis and Electrophysiological Stability Through SERCA2a Regulation in Mice

Yanwen Wang, et al.  Circ Arrhythm Electrophysiol. 2014;7:00-00.

Impaired sarcoplasmic reticular Ca2+ uptake resulting from

  • decreased sarcoplasmic reticulum Ca2+-ATPase type 2a (SERCA2a) expression or activity
  • is a characteristic of heart failure with its associated ventricular arrhythmias.

Recent attempts at gene therapy of these conditions explored strategies

  • enhancing SERCA2a expression and the activity as novel approaches to heart failure management.

We here explore the role of Pak1 in maintaining ventricular Ca2+ homeostasis and electrophysiological stability

  • under both normal physiological and acute and chronic β-adrenergic stress conditions.

Methods and Results—Mice with a cardiomyocyte-specific Pak1 deletion (Pak1cko), but not controls (Pak1f/f), showed

  • high incidences of ventricular arrhythmias and electrophysiological instability
  • during either acute β-adrenergic or chronic β-adrenergic stress leading to hypertrophy,
  • induced by isoproterenol.

Isolated Pak1cko ventricular myocytes correspondingly showed

  • aberrant cellular Ca2+ homeostasis.

Pak1cko hearts showed an associated impairment of SERCA2a function and

  • downregulation of SERCA2a mRNA and protein expression.

Further explorations of the mechanisms underlying the altered transcriptional regulation

  • demonstrated that exposure to control Ad-shC2 virus infection
  • increased SERCA2a protein and mRNA levels after
  • phenylephrine stress in cultured neonatal rat cardiomyocytes.

This was abolished by the

  • Pak1-knockdown in Ad-shPak1–infected neonatal rat cardiomyocytes and
  • increased by constitutive overexpression of active Pak1 (Ad-CAPak1).

We then implicated activation of serum response factor, a transcriptional factor well known for

  • its vital role in the regulation of cardiogenesis genes in the Pak1-dependent regulation of SERCA2a.

Conclusions—These findings indicate that

Pak1 is required to maintain ventricular Ca2+ homeostasis and electrophysiological stability

  • and implicate Pak1 as a novel regulator of cardiac SERCA2a through
  • a transcriptional mechanism

fusion in animal development and in pathophysiology involves expansion of nascent fusion pores

  • formed by protein fusogens to yield an open lumen of cell-size diameter.

Here we explored the enlargement of micron-scale pores in syncytium formation,

  • which was initiated by a well-characterized fusogen baculovirus gp64.

Radial expansion of a single or, more often, of multiple fusion pores proceeds

  • without loss of membrane material in the tight contact zone.

Pore growth requires cell metabolism and is accompanied by

  • a local disassembly of the actin cortex under the pores.

Effects of actin-modifying agents indicate that the actin cortex slows down pore expansion.

We propose that the growth of the strongly bent fusion-pore rim is restricted

  • by a dynamic resistance of the actin network and driven by
  • membrane-bending proteins that are involved in the generation of
  • highly curved intracellular membrane compartments.

Role of forkhead box protein A3 in age-associated metabolic decline

Xinran Maa,1, Lingyan Xua,1, Oksana Gavrilovab, and Elisabetta Muellera,2
PNAS Sep 30, 2014 | 111 | 39 | 14289–14294  http://pnas.org/cgi/doi/10.1073/pnas.1407640111

Significance
This paper reports that the transcription factor forkhead box protein A3 (Foxa3) is

  • directly involved in the development of age-associated obesity and insulin resistance.

Mice that lack the Foxa3 gene

  1. remodel their fat tissues,
  2. store less fat, and
  3. burn more energy as they age.

These mice also live significantly longer.

We show that Foxa3 suppresses a key metabolic cofactor, PGC1α,

  • which is involved in the gene programs that turn on energy expenditure in adipose tissues.

Overall, these findings suggest that Foxa3 contributes to the increased adiposity observed during aging,

  • and that it can be a possible target for the treatment of metabolic disorders.

Aging is associated with increased adiposity and diminished thermogenesis, but

  • the critical transcription factors influencing these metabolic changes late in life are poorly understood.

We recently demonstrated that the winged helix factor forkhead box protein A3 (Foxa3)

  • regulates the expansion of visceral adipose tissue in high-fat diet regimens; however,
  • whether Foxa3 also contributes to the increase in adiposity and the decrease in brown fat activity
  • observed during the normal aging process is currently unknown.

Here we report that during aging, levels of Foxa3 are significantly and selectively

  • up-regulated in brown and inguinal white fat depots, and that
  • midage Foxa3-null mice have increased white fat browning and thermogenic capacity,
  1. decreased adipose tissue expansion,
  2. improved insulin sensitivity, and
  3. increased longevity.

Foxa3 gain-of-function and loss-of-function studies in inguinal adipose depots demonstrated

  • a cell-autonomous function for Foxa3 in white fat tissue browning.

The mechanisms of Foxa3 modulation of brown fat gene programs involve

  • the suppression of peroxisome proliferator activated receptor γ coactivtor 1 α (PGC1α) levels
  • through interference with cAMP responsive element binding protein 1-mediated
  • transcriptional regulation of the PGC1α promoter.

Our data demonstrate a role for Foxa3 in energy expenditure and in age-associated metabolic disorders.

Control of Mitochondrial pH by Uncoupling Protein 4 in Astrocytes Promotes Neuronal Survival

HP Lambert, M Zenger, G Azarias, Jean-Yves Chatton, PJ. Magistretti,§, S Lengacher
JBC (in press) M114.570879  http://www.jbc.org/cgi/doi/10.1074/jbc.M114.570879

Background: Role of uncoupling proteins (UCP) in the brain is unclear.
Results: UCP, present in astrocytes, mediate the intra-mitochondrial acidification leading to a decrease in mitochondrial ATP production.
Conclusion: Astrocyte pH regulation promotes ATP synthesis by glycolysis whose final product, lactate, increases neuronal survival.
Significance: We describe a new role for a brain uncoupling protein.

Brain activity is energetically costly and requires a steady and

  • highly regulated flow of energy equivalents between neural cells.

It is believed that a substantial share of cerebral glucose, the major source of energy of the brain,

  • will preferentially be metabolized in astrocytes via aerobic glycolysis.

The aim of this study was to evaluate whether uncoupling proteins (UCPs),

  • located in the inner membrane of mitochondria,
  • play a role in setting up the metabolic response pattern of astrocytes.

UCPs are believed to mediate the transmembrane transfer of protons

  • resulting in the uncoupling of oxidative phosphorylation from ATP production.

UCPs are therefore potentially important regulators of energy fluxes. The main UCP isoforms

  • expressed in the brain are UCP2, UCP4, and UCP5.

We examined in particular the role of UCP4 in neuron-astrocyte metabolic coupling

  • and measured a range of functional metabolic parameters
  • including mitochondrial electrical potential and pH,
  1. reactive oxygen species production,
  2. NAD/NADH ratio,
  3. ATP/ADP ratio,
  4. CO2 and lactate production, and
  5. oxygen consumption rate (OCR).

In brief, we found that UCP4 regulates the intra-mitochondrial pH of astrocytes

  • which acidifies as a consequence of glutamate uptake,
  • with the main consequence of reducing efficiency of mitochondrial ATP production.
  • the diminished ATP production is effectively compensated by enhancement of glycolysis.
  • this non-oxidative production of energy is not associated with deleterious H2O2 production.

We show that astrocytes expressing more UCP4 produced more lactate,

  • used as energy source by neurons, and had the ability to enhance neuronal survival.

Jose Eduardo des Salles Roselino

The problem with genomics was it was set as explanation for everything. In fact, when something is genetic in nature the genomic reasoning works fine. However, this means whenever an inborn error is found and only in this case the genomic knowledge afterwards may indicate what is wrong and not the completely way to put biology upside down by reading everything in the DNA genetic as well as non-genetic problems.

Read Full Post »


Functional Correlates of Signaling Pathways

Author and Curator: Larry H. Bernstein, MD, FCAP

 

We here move on to a number of specific, key published work on signaling, and look at the possible therapeutic applications to disease states.

Scripps Research Professor Wolfram Ruf and colleagues have identified a key connection between

  • the signaling pathways and the immune system spiraling out of control involving
  • the coagulation system and vascular endothelium that,
  • if disrupted may be a target for sepsis. (Science Daily, Feb 29, 2008).

It may be caused by a bacterial infection that enters the bloodstream, but

  • we now recognize the same cascade not triggered by bacterial invasion.

The acute respiratory distress syndrome (ARDS) has been defined as

  • a severe form of acute lung injury featuring
  • pulmonary inflammation and increased capillary leak.

ARDS is associated with a high mortality rate and accounts for 100,000 deaths annually in the United States. ARDS may arise in a number of clinical situations, especially in patients with sepsis. A well-described pathophysiological model of ARDS is one form of

  • the acute lung inflammation mediated by
  1. neutrophils,
  2. cytokines, and
  3. oxidant stress.

Neutrophils are major effect cells at the frontier of

  • innate immune responses, and they play
  • a critical role in host defense against invading microorganisms.

The tissue injury appears to be related to

  • proteases and toxic reactive oxygen radicals
  • released from activated neutrophils.

In addition, neutrophils can produce cytokines and chemokines that

enhance the acute inflammatory response.

Neutrophil accumulation in the lung plays a pivotal role in the pathogenesis of acute lung injury during sepsis. Directed movement of neutrophils is

  • mediated by a group of chemoattractants,
  • especially CXC chemokines.

Local lung production of CXC chemokines is intensified during experimental sepsis induced by cecal ligation and puncture (CLP).

Sepsis, Multi-organ Dysfunction Syndrome, and Septic Shock: A Conundrum of Signaling Pathways Cascading Out of Control

https://pharmaceuticalintelligence.com/2012/10/13/sepsis-multi-organ-dysfunction-syndrome-and-septic-shock-a-conundrum-of-signaling-pathways-cascading-out-of-control/

Integrins and extracellular matrix in mechanotransduction

ligand binding of integrins

ligand binding of integrins

Integrins are a family of cell surface receptors which

mediate cell–matrix and cell–cell adhesions.

Among other functions they provide an important

mechanical link between the cells external and intracellular environments while

the adhesions that they form also have critical roles in cellular signal-transduction.

Cell–matrix contacts occur at zones in the cell surface where

adhesion receptors cluster and when activated

the receptors bind to ligands in the extracellular matrix.

The extracellular matrix surrounds the cells of tissues and forms the

structural support of tissue which is particularly important in connective tissues.

Cells attach to the extracellular matrix through

specific cell-surface receptors and molecules

including integrins and transmembrane proteoglycans.

The integrin family of αβ heterodimeric receptors act as

cell adhesion molecules

connecting the ECM to the actin cytoskeleton.

The actin cytoskeleton is involved in the regulation of

1.cell motility,

2.cell polarity,

3.cell growth, and

4.cell survival.

The combination of αβ subunits determines

binding specificity and

signaling properties.

Both α and β integrin subunits contain two separate tails, which

penetrate the plasma membrane and possess small cytoplasmic domains which facilitate

the signaling functions of the receptor.

There is some evidence that the β subunit is the principal site for

binding of cytoskeletal and signaling molecules,

whereas the α subunit has a regulatory role. The integrin tails

link the ECM to the actin cytoskeleton within the cell and with cytoplasmic proteins,

such as talin, tensin, and filamin. The extracellular domains of integrin receptors bind the ECM ligands.

binding of integrins depends on ECM divalent cations ch19

binding of integrins depends on ECM divalent cations ch19

integrin coupled to F-actin via linker

integrin coupled to F-actin via linker

http://www.nature.com/nrm/journal/vaop/ncurrent/images/nrm3896-f4.jpg

Schematic of the ‘focal adhesion clutch’ on stiff (a) versus soft (b) extracellular matrix (ECM). In all cases, integrins are coupled to F-actin via linker proteins (for example, talin and vinculin). The linker proteins move backwards (as indicated by the small arrows) as F-actin also moves backwards, under pushing forces from actin polymerization and/or pulling forces from myosin II activity. This mechanism transfers force from actin to integrins, which pull on the ECM. A stiff ECM (a) resists this force so that the bound integrins remain immobile. A compliant matrix (b) deforms under this force (as indicated by the compressed ECM labelled as deformed matrix) so that the bound integrins can also move backwards. Their movement reduces the net loading rate on all the force-bearing elements, which results in altered cellular responses

The ECM is a complex mixture of matrix molecules, including –

  • glycoproteins, collagens, laminins, glycosaminoglycans, proteoglycans,
  • and nonmatrix proteins, – including growth factors

The integrin receptor formed from the binding of α and β subunits is

  • shaped like a globular head supported by two rod-like legs (Figure 1).

Most of the contact between the two subunits occurs in the head region, with

  • the intracellular tails of the subunits forming the legs of the receptor.

Integrin recognition of ligands is not constitutive but

  • is regulated by alteration of integrin affinity for ligand binding.

For integrin binding to ligands to occur

  • the integrin must be primed and activated, both of which involve
  • conformational changes to the receptor.

Linking integrin conformation to function

Figure  Integrin binding to extracellular matrix (ECM). Conformational changes to integrin structure and clustering of subunits which allow enhanced function of the receptor.

Integrins work alongside other proteins such as

cadherins,

immunoglobulin superfamily

cell adhesion molecules,

selectins, and

syndecans

to mediate

cell–cell and

cell–matrix interactions and communication.

Activation of adhesion receptors triggers the formation of matrix contacts in which

bound matrix components,

adhesion receptors,

and associated intracellular cytoskeletal and signaling molecules

form large functional, localized multiprotein complexes.

Cell–matrix contacts are important in a variety of different cell and

tissue properties including

1.embryonic development,

2.inflammatory responses,

3.wound healing,

4.and adult tissue homeostasis.

Integrin extracellular binding activity is regulated from inside the cell and binding to the ECM induces signals that are transmitted into the cell. This bidirectional signaling requires

dynamic,

spatially, and

temporally regulated formation and

disassembly of multiprotein complexes that

form around the short cytoplasmic tails of integrins.

Ligand binding to integrin family members leads to clustering of integrin molecules in the plasma membrane and recruitment of actin filaments and intracellular signaling molecules to the cytoplasmic domain of the integrins. This forms focal adhesion complexes which are able to maintain

not only adhesion to the ECM

but are involved in complex signaling pathways

which include establishing

1.cell polarity,

2.directed cell migration, and

3.maintaining cell growth and survival.

Initial activation through integrin adhesion to matrix recruits up to around 50 diverse signaling molecules

to assemble the focal adhesion complex

which is capable of responding to environmental stimuli efficiently.

Mapping of the integrin

adhesome binding and signaling interactions

a network of 156 components linked together which can be modified by 690 interactions.

Genetic programming occurs with the binding of integrins to the ECM

Signal transduction pathway activation arising from integrin-ECM binding results in

  • changes in gene expression of cells and
  • leads to alterations in cell and tissue function.

Various different effects can arise depending on the

1.cell type,

2.matrix composition, and

3.integrins activated

It has been suggested that integrin-type I collagen interaction is necessary for

  • the phosphorylation and activation of osteoblast-specific transcription factors
  • present in committed osteoprogenitor cells.

During mechanical loading/stimulation of chondrocytes there is an

  1. influx of ions across the cell membrane resulting from
  2. activation of mechanosensitive ion channels
  3. which can be inhibited by subunit-specific anti-integrin blocking antibodies or RGD peptides.

Using these strategies it was identified that

  • α5β1 integrin is a major mechanoreceptor in articular chondrocyte
  • responses to mechanical loading/stimulation.

Osteoarthritic chondrocytes show a depolarization response to 0.33 Hz stimulation

  • in contrast to the hyperpolarization response of normal chondrocytes.

The mechanotransduction pathway in chondrocytes derived from normal and osteoarthritic cartilage

  • both involve recognition of the mechanical stimulus
  • by integrin receptors resulting in
  • the activation of integrin signaling pathways
  • leading to the generation of a cytokine loop.

Normal and osteoarthritic chondrocytes show differences

  • at multiple stages of the mechanotransduction cascade.
Signaling pathways activated in chondrocytes

Signaling pathways activated in chondrocytes

http://dx.doi.org/10.1016/j.matbio.2014.08.007

Chondrocyte integrins are important mediators of cell–matrix interactions in cartilage

  • by regulating the response of the cells to signals from the ECM that
  1. control cell proliferation,
  2. survival,
  3. differentiation,
  4. matrix remodeling.

Integrins participate in development and maintenance of the tissue but also

  • in pathological processes related to matrix destruction, where
  • they likely play a role in the progression of OA.

Cellular adaptation to mechanical stress: role of integrins, Rho, cytoskeletal tension and mechanosensitive ion channels

Cells exhibited four types of mechanical responses:

(1) an immediate viscoelastic response;

(2) early adaptive behavior characterized by pulse-to-pulse attenuation in response to oscillatory forces;

(3) later adaptive cell stiffening with sustained (>15 second) static stresses; and

(4) a large-scale repositioning response with prolonged (>1 minute) stress.

Importantly, these adaptation responses differed biochemically.

The immediate and early responses were affected by

chemically dissipating cytoskeletal prestress (isometric tension), whereas

the later adaptive response was not.

The repositioning response was prevented by

inhibiting tension through interference with Rho signaling,

similar to the case of the immediate and early responses, but it was also prevented by

blocking mechanosensitive ion channels or

by inhibiting Src tyrosine kinases.

All adaptive responses were suppressed by cooling cells to 4°C to slow biochemical remodeling. Thus, cells use multiple mechanisms to sense and respond to static and dynamic changes in the level of mechanical stress applied to integrins.

Microtubule-Stimulated ADP Release, ATP Binding, and Force Generation In Transport Kinesins

All three classes of molecular motor proteins are now known to be

  • large protein families with diverse cellular functions.

Both the kinesin family and the myosin family have been defined and their proteins grouped into subfamilies. Finally, the elusive cytoplasmic version of dynein was identified and a multigene family of flagellar and cytoplasmic dyneins defined. Members of a given motor protein family share

  • significant homology in their motor domains with the defining member,
  • kinesin, dynein or myosin; but they also contain
  • unique protein domains that are specialized for interaction with different cargoes.

This large number of motor proteins may reflect

  • the number of cellular functions that require force generation or movement,
  • ranging from mitosis to morphogenesis to transport of vesicles.

Kinesins are a large family of microtubule (MT)-based motors that play important roles in many cellular activities including

mitosis,

motility, and

intracellular transport

Their involvement in a range of pathological processes

  • also highlights their significance as therapeutic targets and
  • the importance of understanding the molecular basis of their function

They are defined by their motor domains that contain both

  • the microtubule (MT) and
  • ATP binding sites.

Three ATP binding motifs—

  1. the P-loop,
  2. switch I,
  3. switch II–

are highly conserved among

  1. kinesins,
  2. myosin motors, and
  • small GTPases.

They share a conserved mode of MT binding such that

  • MT binding,
  • ATP binding, and
  • hydrolysis

are functionally coupled for efficient MT-based work.

The interior of a cell is a hive of activity, filled with

  • proteins and other items moving from one location to another.

A network of filaments called microtubules forms tracks

  • along which so-called motor proteins carry these items.

Kinesins are one group of motor proteins, and a typical kinesin protein has

  • one end (called the ‘motor domain’) that can attach itself to the microtubules.

The other end links to the cargo being carried, and a ‘neck’ connects the two. When two of these proteins work together,

  • flexible regions of the neck allow the two motor domains to move past one another,
  • which enable the kinesin to essentially walk along a microtubule in a stepwise manner.

Although the two kinesins have been thought to move along the microtubule tracks in different ways, Atherton et al. find that the core mechanism used by their motor domains is the same.

When a motor domain binds to the microtubule, its shape changes,

  • first stimulating release of the breakdown products of ATP from the previous cycle.

This release makes room for a new ATP molecule to bind. The structural changes caused by ATP binding

  • produce larger changes in the flexible neck region that
  • enable individual motor domains within a kinesin pair to
  • co-ordinate their movement and move in a consistent direction.

The major and largely invariant point of contact between kinesin motor domains and the MT is helix-α4,

  • which lies at the tubulin intradimer interface.

The conformational changes in functionally important regions of each motor domain are described,

  • starting with the nucleotide-binding site,
  • from which all other conformational changes emanate.

The nucleotide-binding site (Figure 2) has three major elements:

(1) the P-loop (brown) is visible in all our reconstructions;

(2) loop9 (yellow, contains switch I) undergoes major conformational changes through the ATPase cycle; and

(3) loop11 (red, contains switch II) that connects strand-β7 to helix-α4, the conformation and flexibility of which is

  • determined by MT binding and motor nucleotide state.

Movement and extension of helix-α6 controls neck linker docking

the N-terminus of helix-α6 is closely associated with elements of the nucleotide binding site suggesting that

  • its conformation alters in response to different nucleotide states.

Further,

  • because the orientation of helix-α6 with respect to helix-α4 controls neck linker docking and
  • because helix-α4 is held against the MT during the ATPase cycle,
    • conformational changes in helix-α6 control movement of the neck linker.

Mechanical amplification and force generation involves conformational changes across the motor domain

A key conformational change in the motor domain following Mg-ATP binding is

  • peeling of the central β-sheet from the C-terminus of helix-α4 increasing their separation;
  • this is required to accommodate rotation of helix-α6 and consequent neck linker docking

ATP binding draws loop11 and loop9 closer together; causing

(1) tilting of most of the motor domain not contacting the MT towards the nucleotide-binding site,

(2) rotation, translation, and extension of helix-α6 which we propose contributes to force generation, and

(3) allows neck linker docking and biases movement of the 2nd head towards the MT plus end.

In both motors, microtubule binding promotes

ordered conformations of conserved loops that

stimulate ADP release,

enhance microtubule affinity and

prime the catalytic site for ATP binding.

ATP binding causes only small shifts of these nucleotide-coordinating loops but induces

large conformational changes elsewhere that

allow force generation and

neck linker docking towards the microtubule plus end.

The study presents evidence provide evidence for a conserved ATP-driven

mechanism for kinesins and

reveals the critical mechanistic contribution of the microtubule interface.

Phosphorylation at endothelial cell–cell junctions: Implications for VE-cadherin function

This review summarizes the role of VE-cadherin phosphorylation in the regulation of endothelial cell–cell junctions and highlights how this affects vascular permeability and leukocyte extravasation.

The vascular endothelium is the inner lining of blood vessels and

forms a physical barrier between the vessel lumen and surrounding tissue;

controlling the extravasation of fluids,

plasma proteins and leukocytes.

Changes in the permeability of the endothelium are tightly regulated. Under basal physiological conditions, there is a continuous transfer of substances across the capillary beds. In addition the endothelium can mediate inducible,

transient hyperpermeability

in response to stimulation with inflammatory mediators,

which takes place primarily in post-capillary venules

However, when severe, inflammation may result in dysfunction of the endothelial barrier

  • in various parts of the vascular tree, including large veins, arterioles and capillaries.

Dysregulated permeability is observed in various pathological conditions, such as

  • tumor-induced angiogenesis,
  • cerebrovascular accident and
  • atherosclerosis.

Two fundamentally different pathways regulate endothelial permeability,

  1. the transcellular and
  2. paracellular pathways.

Solutes and cells can pass through the body of endothelial cells via the transcellular pathway, which includes

  • vesicular transport systems,
  • fenestrae, and
  • biochemical transporters.

The paracellular route is controlled by

  • the coordinated opening and closing of endothelial junctions and
  • thereby regulates traffic across the intercellular spaces between endothelial cells.

Endothelial cells are connected by

tight, gap and

adherens junctions,

of which the latter, and particularly the adherens junction component,

vascular endothelial (VE)-cadherin,

are of central importance for the initiation and stabilization of cell–cell contacts.

Although multiple adhesion molecules are localized at endothelial junctions,

  • blocking the adhesive function of VE-cadherin using antibodies
  • is sufficient to disrupt endothelial junctions and
  • to increase endothelial monolayer permeability both in vitro and in vivo.

Like other cadherins, VE-cadherin mediates adhesion via

  • homophilic, calcium-dependent interactions.

This cell–cell adhesion

is strengthened by binding of cytoplasmic proteins, the catenins,

to the C-terminus of VE-cadherin.

VE-cadherin can directly bind

  • β-catenin and plakoglobin, which
  • both associate with the actin binding protein α-catenin.

Initially, α-catenin was thought to directly anchor cadherins to the actin cytoskeleton, but recently it became clear that

  • α-catenin cannot bind to both β-catenin and actin simultaneously.

Numerous lines of evidence indicate that p120-catenin

  • promotes VE-cadherin surface expression and stability at the plasma membrane.

Different models are proposed that describe how

  • p120-catenin regulates cadherin membrane dynamics, including the hypothesis
  • that p120-catenin functions as a ‘cap’ that prevents the interaction of VE-cadherin
  • with the endocytic membrane trafficking machinery.

In addition, p120-catenin might regulate VE-cadherin internalization

  • through interactions with small GTPases.

Cytoplasmic p120-catenin, which is not bound to VE-cadherin, has been shown to

decrease RhoA activity,

elevate active Rac1 and Cdc42, and thereby is thought

to regulate actin cytoskeleton organization and membrane trafficking.

The intact cadherin-catenin complex is required for proper functioning of the adherens junction.

Several mechanisms may be involved in the

  • regulation of the organization and function of the cadherin–catenin complex, including
  1. endocytosis of the complex,
  2. VE-cadherin cleavage and
  3. actin cytoskeleton reorganization.

The remainder of this review primarily focuses on the

role of tyrosine phosphorylation in the control of VE-cadherin-mediated cell–cell adhesion.

Regulation of the adhesive function of VE-cadherin by tyrosine phosphorylation

It is a widely accepted concept that tyrosine phosphorylation of

  • components of the VE–cadherin-catenin complex
  • Correlates with the weakening of cell–cell adhesion.

A general idea has emerged that

tyrosine phosphorylation of the VE-cadherin complex

leads to the uncoupling of VE-cadherin from the actin cytoskeleton

through dissociation of catenins from the cadherin.

However, tyrosine phosphorylation of VE-cadherin

  • is required for efficient transmigration of leukocytes.

This suggests that VE-cadherin-mediated cell–cell contacts

1.are not just pushed open by the migrating leukocytes, but play

2.a more active role in the transmigration process.

A schematic overview of leukocyte adhesion-induced signals leading to VE-cadherin phosphorylation

Regulation of the integrity of endothelial cell–cell contacts by phosphorylation of VE-cadherin.

Regulation of the integrity of endothelial cell–cell contacts by phosphorylation of VE-cadherin

Regulation of the integrity of endothelial cell–cell contacts by phosphorylation of VE-cadherin

N-glycosylation status of E-cadherin controls cytoskeletal dynamics through the organization of distinct β-catenin- and γ-catenin-containing AJs

N-glycosylation of E-cadherin has been shown to inhibit cell–cell adhesion.

Specifically, our recent studies have provided evidence that

  • the reduction of E-cadherin N-glycosylation
  • promoted the recruitment of stabilizing components,
  • vinculin and serine/ threonine protein phosphatase 2A (PP2A), to adherens junctions (AJs)
  • and enhanced the association of AJs with the actin cytoskeleton.

Here, we examined the details of how

N-glycosylation of E-cadherin affected the molecular organization of AJs and their cytoskeletal interactions.

Using the hypoglycosylated E-cadherin variant, V13, we show that

V13/β-catenin complexes preferentially interacted with PP2A and with the microtubule motor protein dynein.

This correlated with dephosphorylation of the microtubule-associated protein tau, suggesting that

increased association of PP2A with V13-containing AJs promoted their tethering to microtubules.

These studies provide the first mechanistic insights into how N-glycosylation of E-cadherin drives changes in AJ composition through

  • the assembly of distinct β-catenin- and γ-catenin-containing scaffolds that impact the interaction with different cytoskeletal components

Cytoskeletal Basis of Ion Channel Function in Cardiac Muscle

MacKinnon. Fig 1  Ion channels exhibit three basic properties

MacKinnon. Fig 1 Ion channels exhibit three basic properties

In order to contract and accommodate the repetitive morphological changes induced by the cardiac cycle, cardiomyocytes

depend on their highly evolved and specialized cytoskeletal apparatus.

Defects in components of the cytoskeleton, in the long term,

affect the ability of the cell to compensate at both functional and structural levels.

In addition to the structural remodeling,

the myocardium becomes increasingly susceptible to altered electrical activity leading to arrhythmogenesis.

The development of arrhythmias secondary to structural remodeling defects has been noted, although the detailed molecular mechanisms are still elusive.

subjects with severe left ventricular chamber dilation such as in DCM can have left bundle branch block (LBBB), while right bundle branch block (RBBB) is more characteristic of right ventricular failure.  LBBB and RBBB have both been repeatedly associated with AV block in heart failure.

The impact of volume overload on structural and electro-cardiographic alterations has been noted in cardiomyopathy patients treated with left ventricular assist device (LVAD) therapy, which puts the heart at mechanical rest.

In LVAD-treated subjects,

QRS- and both QT- and QTc duration decreased,

suggesting that QRS- and QT-duration are significantly influenced by mechanical load and

that the shortening of the action potential duration contributes to the improved contractile performance after LVAD support.

An early postoperative period study after cardiac unloading therapy in 17 HF patients showed that in the first two weeks after LVAD implantation,

HF was associated with a relatively high incidence of ventricular arrhythmias associated with QTc interval prolongation.

In addition, a recent retrospective study of 100 adult patients with advanced HF, treated with an axial-flow HeartMate LVAD suggested that

  • the rate of new-onset monomorphic ventricular tachycardia (MVT) was increased in LVAD treated patients compared to patients given only medical treatment,

The myocardium is exposed to severe and continuous biomechanical stress during each contraction-relaxation cycle. When fiber tension remains uncompensated or simply unbalanced,

it may represent a trigger for arrhythmogenesis caused by cytoskeletal stretching,

which ultimately leads to altered ion channel localization, and subsequent action potential and conduction alterations.

Cytoskeletal proteins not only provide the backbone of the cellular structure, but they also

maintain the shape and flexibility of the different sub-cellular compartments, including the

1.plasma membrane,

2.the double lipid layer, which defines the boundaries of the cell and where

ion channels are mainly localized.

The interaction between the sarcomere, which is the basic for the passive force during diastole and for the restoring force during systole.

Sarcomeric Proteins and Ion Channels

besides fiber stretch associated with mechanical and hemodynamic impairment, cytoskeletal alterations due to primary genetic defects or indirectly to alterations in response to cellular injury can potentially

1.affect ion channel anchoring, and trafficking, as well as

2.functional regulation by second messenger pathways,

3.causing an imbalance in cardiac ionic homeostasis that will trigger arrhythmogenesis.

Intense investigation of

the sarcomeric actin network,

the Z-line structure, and

chaperone molecules docking in the plasma membrane,

has shed new light on the molecular basis of

  • cytoskeletal interactions in regulating ion channels

Actin disruption using cytochalasin D, an agent that interferes with actin polymerization, increased Na+ channel activity in 90% of excised patches tested within 2 min, which indicated that

the integrity of the filamentous actin (F-actin) network was essential for the maintenance of normal Na+ channel function

These data were the first to support a role for the cytoskeleton in cardiac arrhythmias.

Molecular interactions between the cytoskeleton and ion channels

The figure illustrates the interactions between the ion channels on the sarcolemma, and the sarcomere in cardiac myocytes. Note that the Z-line is connected to the cardiac T-tubules. The diagram illustrates the complex protein-protein interactions that occur between structural components of the cytoskeleton and ion channels. The cytoskeleton is involved in regulating the metabolism of ion channels, modifying their expression, localization, and electrical properties.

sarcomere structure

sarcomere structure

It is important to be aware of the enormous variety of clinical presentations that derive from distinct variants in the same pool of genetic factors. Knowledge of these variants could facilitate tailoring the therapy of choice for each patient. In particular,

the recent findings of structural and functional links between

the cytoskeleton and ion channels

could expand the therapeutic interventions in

arrhythmia management in structurally abnormal myocardium, where aberrant binding

between cytoskeletal proteins can directly or indirectly alter ion channel function.

Read Full Post »

Compilation of References in Leaders in Pharmaceutical Intelligence about proteomics, metabolomics, signaling pathways, and cell regulation


Compilation of References in Leaders in Pharmaceutical Intelligence about
proteomics, metabolomics, signaling pathways, and cell regulation

Curator: Larry H. Bernstein, MD, FCAP

 

Proteomics

  1. The Human Proteome Map Completed
    Reporter and Curator: Larry H. Bernstein, MD, FCAP
    https://pharmaceuticalintelligence.com/2014/08/28/the-human-proteome-map-completed/
  1. Proteomics – The Pathway to Understanding and Decision-making in Medicine
    Author and Curator, Larry H Bernstein, MD, FCAP
    https://pharmaceuticalintelligence.com/2014/06/24/proteomics-the-pathway-to-understanding-and-decision-making-in-medicine/
  1. Advances in Separations Technology for the “OMICs” and Clarification of Therapeutic Targets
    Author and Curator, Larry H Bernstein, MD, FCAP
    https://pharmaceuticalintelligence.com/2012/10/22/advances-in-separations-technology-for-the-omics-and-clarification-of-therapeutic-targets/
  1. Expanding the Genetic Alphabet and Linking the Genome to the Metabolome
    Author and Curator, Larry H Bernstein, MD, FCAP
    https://pharmaceuticalintelligence.com/2012/09/24/expanding-the-genetic-alphabet-and-linking-the-genome-to-the-metabolome/
  1. Synthesizing Synthetic Biology: PLOS Collections
    Reporter: Aviva Lev-Ari
    https://pharmaceuticalintelligence.com/2012/08/17/synthesizing-synthetic-biology-plos-collections/

 

Metabolomics

  1. Extracellular evaluation of intracellular flux in yeast cells
    Larry H. Bernstein, MD, FCAP, Reviewer and Curator
    https://pharmaceuticalintelligence.com/2014/08/25/extracellular-evaluation-of-intracellular-flux-in-yeast-cells/ 
  2. Metabolomic analysis of two leukemia cell lines. I.
    Larry H. Bernstein, MD, FCAP, Reviewer and Curator
    http://pharmaceuticalintelligence.com/2014/08/23/metabolomic-analysis-of-two-leukemia-cell-lines-_i/ 
  3. Metabolomic analysis of two leukemia cell lines. II.
    Larry H. Bernstein, MD, FCAP, Reviewer and Curator
    https://pharmaceuticalintelligence.com/2014/08/24/metabolomic-analysis-of-two-leukemia-cell-lines-ii/ 
  4. Metabolomics, Metabonomics and Functional Nutrition: the next step in nutritional metabolism and biotherapeutics
    Reviewer and Curator, Larry H. Bernstein, MD, FCAP
    https://pharmaceuticalintelligence.com/2014/08/22/metabolomics-metabonomics-and-functional-nutrition-the-next-step-in-nutritional-metabolism-and-biotherapeutics/ 
  5. Buffering of genetic modules involved in tricarboxylic acid cycle metabolism provides homeomeostatic regulation
    Larry H. Bernstein, MD, FCAP, Reviewer and curator
    https://pharmaceuticalintelligence.com/2014/08/27/buffering-of-genetic-modules-involved-in-tricarboxylic-acid-cycle-metabolism-provides-homeomeostatic-regulation/

 

Metabolic Pathways

  1. Pentose Shunt, Electron Transfer, Galactose, more Lipids in brief
    Reviewer and Curator: Larry H. Bernstein, MD, FCAP
    https://pharmaceuticalintelligence.com/2014/08/21/pentose-shunt-electron-transfer-galactose-more-lipids-in-brief/
  2. Mitochondria: More than just the “powerhouse of the cell”
    Reviewer and Curator: Ritu Saxena
    https://pharmaceuticalintelligence.com/2012/07/09/mitochondria-more-than-just-the-powerhouse-of-the-cell/
  3. Mitochondrial fission and fusion: potential therapeutic targets?
    Reviewer and Curator: Ritu saxena
    https://pharmaceuticalintelligence.com/2012/10/31/mitochondrial-fission-and-fusion-potential-therapeutic-target/ 
  4. Mitochondrial mutation analysis might be “1-step” away
    Reviewer and Curator: Ritu Saxena
    https://pharmaceuticalintelligence.com/2012/08/14/mitochondrial-mutation-analysis-might-be-1-step-away/
  5. Selected References to Signaling and Metabolic Pathways in PharmaceuticalIntelligence.com
    Curator: Larry H. Bernstein, MD, FCAP
    https://pharmaceuticalintelligence.com/2014/08/14/selected-references-to-signaling-and-metabolic-pathways-in-leaders-in-pharmaceutical-intelligence/
  6. Metabolic drivers in aggressive brain tumors
    Prabodh Kandal, PhD
    https://pharmaceuticalintelligence.com/2012/11/11/metabolic-drivers-in-aggressive-brain-tumors/ 
  7. Metabolite Identification Combining Genetic and Metabolic Information: Genetic association links unknown metabolites to functionally related genes
    Author and Curator: Aviva Lev-Ari, PhD, RD
    https://pharmaceuticalintelligence.com/2012/10/22/metabolite-identification-combining-genetic-and-metabolic-information-genetic-association-links-unknown-metabolites-to-functionally-related-genes/
  8. Mitochondria: Origin from oxygen free environment, role in aerobic glycolysis, metabolic adaptation
    Author and curator:Larry H Bernstein, MD, FCAP
    https://pharmaceuticalintelligence.com/2012/09/26/mitochondria-origin-from-oxygen-free-environment-role-in-aerobic-glycolysis-metabolic-adaptation/
  9. Therapeutic Targets for Diabetes and Related Metabolic Disorders
    Reporter, Aviva Lev-Ari, PhD, RD
    https://pharmaceuticalintelligence.com/2012/08/20/therapeutic-targets-for-diabetes-and-related-metabolic-disorders/
  10. Buffering of genetic modules involved in tricarboxylic acid cycle metabolism provides homeomeostatic regulation
    Larry H. Bernstein, MD, FCAP, Reviewer and curator
    https://pharmaceuticalintelligence.com/2014/08/27/buffering-of-genetic-modules-involved-in-tricarboxylic-acid-cycle-metabolism-provides-homeomeostatic-regulation/
  11. The multi-step transfer of phosphate bond and hydrogen exchange energy
    Curator:Larry H. Bernstein, MD, FCAP,
    https://pharmaceuticalintelligence.com/2014/08/19/the-multi-step-transfer-of-phosphate-bond-and-hydrogen-exchange-energy/
  12. Studies of Respiration Lead to Acetyl CoA
    Author and Curator: Larry H. Bernstein, MD, FCAP
    https://pharmaceuticalintelligence.com/2014/08/18/studies-of-respiration-lead-to-acetyl-coa/
  13. Lipid Metabolism
    Author and Curator: Larry H. Bernstein, MD, FCAP
    https://pharmaceuticalintelligence.com/2014/08/15/lipid-metabolism/
  14. Carbohydrate Metabolism
    Author and Curator: Larry H. Bernstein, MD, FCAP
    https://pharmaceuticalintelligence.com/2014/08/13/carbohydrate-metabolism/
  15. Prologue to Cancer – e-book Volume One – Where are we in this journey?
    Author and Curator: Larry H. Bernstein, MD, FCAP
    https://pharmaceuticalintelligence.com/2014/04/13/prologue-to-cancer-ebook-4-where-are-we-in-this-journey/
  16. Introduction – The Evolution of Cancer Therapy and Cancer Research: How We Got Here?
    Author and Curator: Larry H. Bernstein, MD, FCAP
    https://pharmaceuticalintelligence.com/2014/04/04/introduction-the-evolution-of-cancer-therapy-and-cancer-research-how-we-got-here/
  17. Inhibition of the Cardiomyocyte-Specific Kinase TNNI3K
    Author and Curator: Larry H. Bernstein, MD, FCAP
    https://pharmaceuticalintelligence.com/2013/11/01/inhibition-of-the-cardiomyocyte-specific-kinase-tnni3k/
  18. The Binding of Oligonucleotides in DNA and 3-D Lattice Structures
    Author and Curator: Larry H. Bernstein, MD, FCAP
    https://pharmaceuticalintelligence.com/2013/05/15/the-binding-of-oligonucleotides-in-dna-and-3-d-lattice-structures/
  19. Mitochondrial Metabolism and Cardiac Function
    Author and Curator: Larry H. Bernstein, MD, FCAP
    https://pharmaceuticalintelligence.com/2013/04/14/mitochondrial-metabolism-and-cardiac-function/
  20. How Methionine Imbalance with Sulfur-Insufficiency Leads to Hyperhomocysteinemia
    Curator: Larry H. Bernstein, MD, FCAP
    https://pharmaceuticalintelligence.com/2013/04/04/sulfur-deficiency-leads_to_hyperhomocysteinemia/
  21. AMPK Is a Negative Regulator of the Warburg Effect and Suppresses Tumor Growth In Vivo
    Author and Curator: SJ. Williams
    https://pharmaceuticalintelligence.com/2013/03/12/ampk-is-a-negative-regulator-of-the-warburg-effect-and-suppresses-tumor-growth-in-vivo/
  22. A Second Look at the Transthyretin Nutrition Inflammatory Conundrum
    Author and Curator: Larry H. Bernstein, MD, FCAP
    https://pharmaceuticalintelligence.com/2012/12/03/a-second-look-at-the-transthyretin-nutrition-inflammatory-conundrum/
  23. Overview of Posttranslational Modification (PTM)
    Writer and Curator: Larry H. Bernstein, MD, FCAP
    https://pharmaceuticalintelligence.com/2014/07/29/overview-of-posttranslational-modification-ptm/
  24. Malnutrition in India, high newborn death rate and stunting of children age under five years
    Writer and Curator: Larry H. Bernstein, MD, FCAP
    https://pharmaceuticalintelligence.com/2014/07/15/malnutrition-in-india-high-newborn-death-rate-and-stunting-of-children-age-under-five-years/
  25. Update on mitochondrial function, respiration, and associated disorders
    Writer and Curator: Larry H. Bernstein, MD, FCAP
    https://pharmaceuticalintelligence.com/2014/07/08/update-on-mitochondrial-function-respiration-and-associated-disorders/
  26. Omega-3 fatty acids, depleting the source, and protein insufficiency in renal disease
    Larry H. Bernstein, MD, FCAP, Curator
    https://pharmaceuticalintelligence.com/2014/07/06/omega-3-fatty-acids-depleting-the-source-and-protein-insufficiency-in-renal-disease/ 
  27. Late Onset of Alzheimer’s Disease and One-carbon Metabolism
    Reporter and Curator: Dr. Sudipta Saha, Ph.D.
    https://pharmaceuticalintelligence.com/2013/05/06/alzheimers-disease-and-one-carbon-metabolism/
  28. Problems of vegetarianism
    Reporter and Curator: Dr. Sudipta Saha, Ph.D.
    https://pharmaceuticalintelligence.com/2013/04/22/problems-of-vegetarianism/

 

Signaling Pathways

  1. Introduction to e-Series A: Cardiovascular Diseases, Volume Four Part 2: Regenerative Medicine
    Larry H. Bernstein, MD, FCAP, writer, and Aviva Lev- Ari, PhD, RN  https://pharmaceuticalintelligence.com/2014/04/27/larryhbernintroduction_to_cardiovascular_diseases-translational_medicine-part_2/
  2. Epilogue: Envisioning New Insights in Cancer Translational Biology
    Series C: e-Books on Cancer & Oncology
    Author & Curator: Larry H. Bernstein, MD, FCAP, Series C Content Consultant
    https://pharmaceuticalintelligence.com/2014/03/29/epilogue-envisioning-new-insights/
  3. Ca2+-Stimulated Exocytosis:  The Role of Calmodulin and Protein Kinase C in Ca2+ Regulation of Hormone and Neurotransmitter  Writer and Curator: Larry H Bernstein, MD, FCAP and Curator and Content Editor: Aviva Lev-Ari, PhD, RN
    https://pharmaceuticalintelligence.com/2013/12/23/calmodulin-and-protein-kinase-c-drive-the-ca2-regulation-of-hormone-and-neurotransmitter-release-that-triggers-ca2-stimulated-exocy
  4. Cardiac Contractility & Myocardial Performance: Therapeutic Implications of Ryanopathy (Calcium Release-related Contractile Dysfunction) and Catecholamine Responses
    Author, and Content Consultant to e-SERIES A: Cardiovascular Diseases: Justin Pearlman, MD, PhD, FACC
    Author and Curator: Larry H Bernstein, MD, FCAP and Article Curator: Aviva Lev-Ari, PhD, RN
    https://pharmaceuticalintelligence.com/2013/08/28/cardiac-contractility-myocardium-performance-ventricular-arrhythmias-and-non-ischemic-heart-failure-therapeutic-implications-for-cardiomyocyte-ryanopathy-calcium-release-related-contractile/
  5. Role of Calcium, the Actin Skeleton, and Lipid Structures in Signaling and Cell Motility
    Author and Curator: Larry H Bernstein, MD, FCAP Author: Stephen Williams, PhD, and Curator: Aviva Lev-Ari, PhD, RN
    https://pharmaceuticalintelligence.com/2013/08/26/role-of-calcium-the-actin-skeleton-and-lipid-structures-in-signaling-and-cell-motility/
  6. Identification of Biomarkers that are Related to the Actin Cytoskeleton
    Larry H Bernstein, MD, FCAP, Author and Curator
    https://pharmaceuticalintelligence.com/2012/12/10/identification-of-biomarkers-that-are-related-to-the-actin-cytoskeleton/
  7. Advanced Topics in Sepsis and the Cardiovascular System at its End Stage
    Author and Curator: Larry H Bernstein, MD, FCAP
    https://pharmaceuticalintelligence.com/2013/08/18/advanced-topics-in-Sepsis-and-the-Cardiovascular-System-at-its-End-Stage/
  8. The Delicate Connection: IDO (Indolamine 2, 3 dehydrogenase) and Cancer Immunology
    Demet Sag, PhD, Author and Curator
    https://pharmaceuticalintelligence.com/2013/08/04/the-delicate-connection-ido-indolamine-2-3-dehydrogenase-and-immunology/
  9. IDO for Commitment of a Life Time: The Origins and Mechanisms of IDO, indolamine 2, 3-dioxygenase
    Demet Sag, PhD, Author and Curator
    https://pharmaceuticalintelligence.com/2013/08/04/ido-for-commitment-of-a-life-time-the-origins-and-mechanisms-of-ido-indolamine-2-3-dioxygenase/
  10. Confined Indolamine 2, 3 dioxygenase (IDO) Controls the Homeostasis of Immune Responses for Good and Bad
    Author and Curator: Demet Sag, PhD, CRA, GCP
    https://pharmaceuticalintelligence.com/2013/07/31/confined-indolamine-2-3-dehydrogenase-controls-the-hemostasis-of-immune-responses-for-good-and-bad/
  11. Signaling Pathway that Makes Young Neurons Connect was discovered @ Scripps Research Institute
    Reporter: Aviva Lev-Ari, PhD, RN
    https://pharmaceuticalintelligence.com/2013/06/26/signaling-pathway-that-makes-young-neurons-connect-was-discovered-scripps-research-institute/
  12. Naked Mole Rats Cancer-Free
    Writer and Curator: Larry H. Bernstein, MD, FCAP
    https://pharmaceuticalintelligence.com/2013/06/20/naked-mole-rats-cancer-free/
  13. Amyloidosis with Cardiomyopathy
    Writer and Curator: Larry H. Bernstein, MD, FCAP
    https://pharmaceuticalintelligence.com/2013/03/31/amyloidosis-with-cardiomyopathy/
  14. Liver endoplasmic reticulum stress and hepatosteatosis
    Larry H Bernstein, MD, FACP
    https://pharmaceuticalintelligence.com/2013/03/10/liver-endoplasmic-reticulum-stress-and-hepatosteatosis/
  15. The Molecular Biology of Renal Disorders: Nitric Oxide – Part III
    Curator and Author: Larry H Bernstein, MD, FACP
    https://pharmaceuticalintelligence.com/2012/11/26/the-molecular-biology-of-renal-disorders/
  16. Nitric Oxide Function in Coagulation – Part II
    Curator and Author: Larry H. Bernstein, MD, FCAP
    https://pharmaceuticalintelligence.com/2012/11/26/nitric-oxide-function-in-coagulation/
  17. Nitric Oxide, Platelets, Endothelium and Hemostasis
    Curator and Author: Larry H Bernstein, MD, FACP
    https://pharmaceuticalintelligence.com/2012/11/08/nitric-oxide-platelets-endothelium-and-hemostasis/
  18. Interaction of Nitric Oxide and Prostacyclin in Vascular Endothelium
    Curator and Author: Larry H Bernstein, MD, FACP
    https://pharmaceuticalintelligence.com/2012/09/14/interaction-of-nitric-oxide-and-prostacyclin-in-vascular-endothelium/
  19. Nitric Oxide and Immune Responses: Part 1
    Curator and Author:  Aviral Vatsa PhD, MBBS
    https://pharmaceuticalintelligence.com/2012/10/18/nitric-oxide-and-immune-responses-part-1/
  20. Nitric Oxide and Immune Responses: Part 2
    Curator and Author:  Aviral Vatsa PhD, MBBS
    https://pharmaceuticalintelligence.com/2012/10/28/nitric-oxide-and-immune-responses-part-2/
  21. Nitric Oxide and iNOS have Key Roles in Kidney Diseases – Part II
    Curator and Author: Larry H Bernstein, MD, FACP
    https://pharmaceuticalintelligence.com/2012/11/26/nitric-oxide-and-inos-have-key-roles-in-kidney-diseases/
  22. New Insights on Nitric Oxide donors – Part IV
    Curator and Author: Larry H Bernstein, MD, FACP
    https://pharmaceuticalintelligence.com/2012/11/26/new-insights-on-no-donors/
  23. Crucial role of Nitric Oxide in Cancer
    Curator and Author: Ritu Saxena, Ph.D.
    https://pharmaceuticalintelligence.com/2012/10/16/crucial-role-of-nitric-oxide-in-cancer/
  24. Nitric Oxide has a ubiquitous role in the regulation of glycolysis -with a concomitant influence on mitochondrial function
    Curator and Author: Larry H Bernstein, MD, FACP
    https://pharmaceuticalintelligence.com/2012/09/16/nitric-oxide-has-a-ubiquitous-role-in-the-regulation-of-glycolysis-with-a-concomitant-influence-on-mitochondrial-function/
  25. Nitric Oxide and Immune Responses: Part 2
    Author and Curator: Aviral Vatsa, PhD, MBBS
    https://pharmaceuticalintelligence.com/2012/10/28/nitric-oxide-and-immune-responses-part-2/
  26. Mitochondrial Damage and Repair under Oxidative Stress
    Author and Curator: Larry H. Bernstein, MD, FCAP
    https://pharmaceuticalintelligence.com/2012/10/28/mitochondrial-damage-and-repair-under-oxidative-stress/
  27. Is the Warburg Effect the cause or the effect of cancer: A 21st Century View?
    Curator and Author: Larry H Bernstein, MD, FACP
    https://pharmaceuticalintelligence.com/2012/10/17/is-the-warburg-effect-the-cause-or-the-effect-of-cancer-a-21st-century-view/
  28. Targeting Mitochondrial-bound Hexokinase for Cancer Therapy
    Curator and Author: Ziv Raviv, PhD, RN 04/06/2013
    https://pharmaceuticalintelligence.com/2013/04/06/targeting-mitochondrial-bound-hexokinase-for-cancer-therapy/
  29. Ubiquinin-Proteosome pathway, autophagy, the mitochondrion, proteolysis and cell apoptosis
    Curator and Author: Larry H Bernstein, MD, FACP
    https://pharmaceuticalintelligence.com/2012/10/30/ubiquinin-proteosome-pathway-autophagy-the-mitochondrion-proteolysis-and-cell-apoptosis/
  30. Ubiquitin-Proteosome pathway, Autophagy, the Mitochondrion, Proteolysis and Cell Apoptosis: Part III
    Curator and Author: Larry H Bernstein, MD, FACP
    https://pharmaceuticalintelligence.com/2013/02/14/ubiquinin-proteosome-pathway-autophagy-the-mitochondrion-proteolysis-and-cell-apoptosis-reconsidered/
  31. Biochemistry of the Coagulation Cascade and Platelet Aggregation – Part I
    Curator and Author: Larry H Bernstein, MD, FACP
    https://pharmaceuticalintelligence.com/2012/11/26/biochemistry-of-the-coagulation-cascade-and-platelet-aggregation/

 

Genomics, Transcriptomics, and Epigenetics

  1. What is the meaning of so many RNAs?
    Writer and Curator: Larry H. Bernstein, MD, FCAP
    https://pharmaceuticalintelligence.com/2014/08/06/what-is-the-meaning-of-so-many-rnas/
  2. RNA and the transcription the genetic code
    Larry H. Bernstein, MD, FCAP, Writer and Curator
    https://pharmaceuticalintelligence.com/2014/08/02/rna-and-the-transcription-of-the-genetic-code/
  3. A Primer on DNA and DNA Replication
    Writer and Curator: Larry H. Bernstein, MD, FCAP
    https://pharmaceuticalintelligence.com/2014/07/29/a_primer_on_dna_and_dna_replication/
  4. Pathology Emergence in the 21st Century
    Author and Curator: Larry Bernstein, MD, FCAP
    https://pharmaceuticalintelligence.com/2014/08/03/pathology-emergence-in-the-21st-century/
  5. RNA and the transcription the genetic code
    Writer and Curator, Larry H. Bernstein, MD, FCAP
    https://pharmaceuticalintelligence.com/2014/08/02/rna-and-the-transcription-of-the-genetic-code/
  6. Commentary on Biomarkers for Genetics and Genomics of Cardiovascular Disease: Views by Larry H Bernstein, MD, FCAP
    Author: Larry H Bernstein, MD, FCAP
    https://pharmaceuticalintelligence.com/2014/07/16/commentary-on-biomarkers-for-genetics-and-genomics-of-cardiovascular-disease-views-by-larry-h-bernstein-md-fcap/
  7. Observations on Finding the Genetic Links in Common Disease: Whole Genomic Sequencing Studies
    Author an Curator: Larry H Bernstein, MD, FCAP
    https://pharmaceuticalintelligence.com/2013/05/18/observations-on-finding-the-genetic-links/
  8. Silencing Cancers with Synthetic siRNAs
    Larry H. Bernstein, MD, FCAP, Reviewer and Curator
    https://pharmaceuticalintelligence.com/2013/12/09/silencing-cancers-with-synthetic-sirnas/
  9. Cardiometabolic Syndrome and the Genetics of Hypertension: The Neuroendocrine Transcriptome Control Points
    Reporter: Aviva Lev-Ari, PhD, RN
    https://pharmaceuticalintelligence.com/2013/12/12/cardiometabolic-syndrome-and-the-genetics-of-hypertension-the-neuroendocrine-transcriptome-control-points/
  10. Developments in the Genomics and Proteomics of Type 2 Diabetes Mellitus and Treatment Targets
    Larry H. Bernstein, MD, FCAP, Reviewer and Curator
    https://pharmaceuticalintelligence.com/2013/12/08/developments-in-the-genomics-and-proteomics-of-type-2-diabetes-mellitus-and-treatment-targets/
  11. CT Angiography & TrueVision™ Metabolomics (Genomic Phenotyping) for new Therapeutic Targets to Atherosclerosis
    Reporter: Aviva Lev-Ari, PhD, RN
    https://pharmaceuticalintelligence.com/2013/11/15/ct-angiography-truevision-metabolomics-genomic-phenotyping-for-new-therapeutic-targets-to-atherosclerosis/
  12. CRACKING THE CODE OF HUMAN LIFE: The Birth of BioInformatics & Computational Genomics
    Genomics Curator, Larry H Bernstein, MD, FCAP
    https://pharmaceuticalintelligence.com/2014/08/30/cracking-the-code-of-human-life-the-birth-of-bioinformatics-computational-genomics/
  13. Big Data in Genomic Medicine
    Author and Curator, Larry H Bernstein, MD, FCAP
    https://pharmaceuticalintelligence.com/2012/12/17/big-data-in-genomic-medicine/
  14.  From Genomics of Microorganisms to Translational Medicine
    Author and Curator: Demet Sag, PhD
    https://pharmaceuticalintelligence.com/2014/03/20/without-the-past-no-future-but-learn-and-move-genomics-of-microorganisms-to-translational-medicine/
  15.  Summary of Genomics and Medicine: Role in Cardiovascular Diseases
    Author and Curator, Larry H Bernstein, MD, FCAP
    https://pharmaceuticalintelligence.com/2014/01/06/summary-of-genomics-and-medicine-role-in-cardiovascular-diseases/

Read Full Post »


Selected References to Signaling and Metabolic Pathways in PharmaceuticalIntelligence.com

Curator: Larry H. Bernstein, MD, FCAP

 

This is an added selection of articles in Leaders in Pharmaceutical Intelligence after the third portion of the discussion in a series of articles that began with signaling and signaling pathways. There are fine features on the functioning of enzymes and proteins, on sequential changes in a chain reaction, and on conformational changes that we shall return to.  These are critical to developing a more complete understanding of life processes.  I have indicated that many of the protein-protein interactions or protein-membrane interactions and associated regulatory features have been referred to previously, but the focus of the discussion or points made were different.

  1. Signaling and signaling pathways
  2. Signaling transduction tutorial.
  3. Carbohydrate metabolism3.1  Selected References to Signaling and Metabolic Pathways in Leaders in Pharmaceutical Intelligence
  4. Lipid metabolism
  5. Protein synthesis and degradation
  6. Subcellular structure
  7. Impairments in pathological states: endocrine disorders; stress hypermetabolism; cancer.

Selected References to Signaling and Metabolic Pathwayspublished in this Open Access Online Scientific Journal, include the following:

Update on mitochondrial function, respiration, and associated disorders

Curator and writer: Larry H. Benstein, MD, FCAP

https://pharmaceuticalintelligence.com/2014/07/08/update-on-mitochondrial-function-respiration-and-associated-disorders/

A Synthesis of the Beauty and Complexity of How We View Cancer


Cancer Volume One – Summary

A Synthesis of the Beauty and Complexity of How We View Cancer

Author: Larry H. Bernstein, MD, FCAP

https://pharmaceuticalintelligence.com/2014/03/26/a-synthesis-of-the-beauty-and-complexity-of-how-we-view-cancer/

Introduction – The Evolution of Cancer Therapy and Cancer Research: How We Got Here?

Author and Curator: Larry H Bernstein, MD, FCAP

https://pharmaceuticalintelligence.com/2014/04/04/introduction-the-evolution-of-cancer-therapy-and-cancer-research-how-we-got-here/

 The Centrality of Ca(2+) Signaling and Cytoskeleton Involving Calmodulin Kinases and Ryanodine Receptors in Cardiac Failure, Arterial Smooth Muscle, Post-ischemic Arrhythmia, Similarities and Differences, and Pharmaceutical Targets

Author and Curator: Larry H Bernstein, MD, FCAP, 
Author, and Content Consultant to e-SERIES A: Cardiovascular Diseases: Justin Pearlman, MD, PhD, FACC
And Curator: Aviva Lev-Ari, PhD, RN

https://pharmaceuticalintelligence.com/2013/09/08/the-centrality-of-ca2-signaling-and-cytoskeleton-involving-calmodulin-kinases-and-ryanodine-receptors-in-cardiac-failure

Renal Distal Tubular Ca2+ Exchange Mechanism in Health and Disease

Author and Curator: Larry H. Bernstein, MD, FCAP
Curator:  Stephen J. Williams, PhD
and Curator: Aviva Lev-Ari, PhD, RN

https://pharmaceuticalintelligence.com/2013/09/02/renal-distal-tubular-ca2-exchange-mechanism-in-health-and-disease/

Mitochondrial Metabolism and Cardiac Function

Curator: Larry H Bernstein, MD, FACP

https://pharmaceuticalintelligence.com/2013/04/14/mitochondrial-metabolism-and-cardiac-function/

Mitochondrial Dysfunction and Cardiac Disorders

Curator: Larry H Bernstein, MD, FACP

https://pharmaceuticalintelligence.com/2013/04/14/mitochondrial-metabolism-and-cardiac-function/

Reversal of Cardiac mitochondrial dysfunction

Curator: Larry H Bernstein, MD, FACP

https://pharmaceuticalintelligence.com/2013/04/14/reversal-of-cardiac-mitochondrial-dysfunction/

Advanced Topics in Sepsis and the Cardiovascular System  at its End Stage

Author: Larry H Bernstein, MD, FCAP

https://pharmaceuticalintelligence.com/2013/08/18/advanced-topics-in-Sepsis-and-the-Cardiovascular-System-at-its-End-Stage/

Ubiquinin-Proteosome pathway, autophagy, the mitochondrion, proteolysis and cell apoptosis

Curator: Larry H Bernstein, MD, FACP

https://pharmaceuticalintelligence.com/2012/10/30/ubiquinin-proteosome-pathway-autophagy-the-mitochondrion-proteolysis-and-cell-apoptosis/

Ubiquitin-Proteosome pathway, Autophagy, the Mitochondrion, Proteolysis and Cell Apoptosis: Part III

Curator: Larry H Bernstein, MD, FCAP

https://pharmaceuticalintelligence.com/2013/02/14/ubiquinin-proteosome-pathway-autophagy-the-mitochondrion-proteolysis-and-cell-apoptosis-reconsidered/

 

Nitric Oxide, Platelets, Endothelium and Hemostasis (Coagulation Part II)

Curator: Larry H. Bernstein, MD, FCAP 

https://pharmaceuticalintelligence.com/2012/11/08/nitric-oxide-platelets-endothelium-and-hemostasis/


Mitochondrial Damage and Repair under Oxidative Stress

Curator: Larry H Bernstein, MD, FCAP

https://pharmaceuticalintelligence.com/2012/10/28/mitochondrial-damage-and-repair-under-oxidative-stress/

Mitochondria: Origin from oxygen free environment, role in aerobic glycolysis, metabolic adaptation

Reporter and Curator: Larry H Bernstein, MD, FACP

https://pharmaceuticalintelligence.com/2012/09/26/mitochondria-origin-from-oxygen-free-environment-role-in-aerobic-glycolysis-metabolic-adaptation/

 

Nitric Oxide has a Ubiquitous Role in the Regulation of Glycolysis – with a Concomitant Influence on Mitochondrial Function

Reporter, Editor, and Topic Co-Leader: Larry H. Bernstein, MD, FCAP

https://pharmaceuticalintelligence.com/2012/09/16/nitric-oxide-has-a-ubiquitous-role-in-the-regulation-of-glycolysis-with-a-concomitant-influence-on-mitochondrial-function/


Mitochondria and Cancer: An overview of mechanisms

Author and Curator: Ritu Saxena, Ph.D.

https://pharmaceuticalintelligence.com/2012/09/01/mitochondria-and-cancer-an-overview/

Mitochondria: More than just the “powerhouse of the cell”

Author and Curator: Ritu Saxena, Ph.D.

https://pharmaceuticalintelligence.com/2012/07/09/mitochondria-more-than-just-the-powerhouse-of-the-cell/

Overview of Posttranslational Modification (PTM)

Curator: Larry H. Bernstein, MD, FCAP

https://pharmaceuticalintelligence.com/2014/07/29/overview-of-posttranslational-modification-ptm/


Ubiquitin Pathway Involved in Neurodegenerative Diseases

Author and curator: Larry H Bernstein, MD,  FCAP

https://pharmaceuticalintelligence.com/2013/02/15/ubiquitin-pathway-involved-in-neurodegenerative-diseases/

Is the Warburg Effect the Cause or the Effect of Cancer: A 21st Century View?

Author: Larry H. Bernstein, MD, FCAP 

https://pharmaceuticalintelligence.com/2012/10/17/is-the-warburg-effect-the-cause-or-the-effect-of-cancer-a-21st-century-view/

New Insights on Nitric Oxide donors – Part IV

Curator and Author: Larry H. Bernstein, MD, FCAP

https://pharmaceuticalintelligence.com/2012/11/26/new-insights-on-no-donors/

Perspectives on Nitric Oxide in Disease Mechanisms [Kindle Edition]

Margaret Baker PhD (Author), Tilda Barliya PhD (Author), Anamika Sarkar PhD (Author), Ritu Saxena PhD (Author), Stephen J. Williams PhD (Author), Larry Bernstein MD FCAP (Editor), Aviva Lev-Ari PhD RN (Editor), Aviral Vatsa PhD (Editor)

https://pharmaceuticalintelligence.com/biomed-e-books/series-a-e-books-on-cardiovascular-diseases/perspectives-on-nitric-oxide-in-disease-mechanisms-v2/

 

Summary

Nitric oxide and its role in vascular biology

Signal transmission by a gas that is produced by one cell, penetrates through membranes and regulates the function of another cell represents an entirely new principle for signaling in biological systems.   All compounds that inhibit endothelium-derived relaxation-factor (EDRF) have one property in common, redox activity, which accounts for their inhibitory action on EDRF. One exception is hemoglobin, which inactivates EDRF by binding to it. Furchgott, Ignarro and Murad received the Nobel Prize in Physiology and Medicine for discovery of EDRF in 1998 and demonstrating that it might be nitric oxide (NO) based on a study of the transient relaxations of endothelium-denuded rings of rabbit aorta.  These investigators working independently demonstrated that NO is indeed produced by mammalian cells and that NO has specific biological roles in the human body. These studies highlighted the role of NO in cardiovascular, nervous and immune systems. In cardiovascular system NO was shown to cause relaxation of vascular smooth muscle cells causing vasodilatation, in nervous system NO acts as a signaling molecule and in immune system it is used against pathogens by the phagocytosis cells. These pioneering studies opened the path of investigation of role of NO in biology.

NO modulates vascular tone, fibrinolysis, blood pressure and proliferation of vascular smooth muscles. In cardiovascular system disruption of NO pathways or alterations in NO production can result in preponderance to hypertension, hypercholesterolemia, diabetes mellitus, atherosclerosis and thrombosis. The three enzyme isoforms of NO synthase family are responsible for generating NO in different tissues under various circumstances.

Reduction in NO production is implicated as one of the initial factors in initiating endothelial dysfunction. This reduction could be due to

  • reduction in eNOS production
  • reduction in eNOS enzymatic activity
  • reduced bioavailability of NO

Nitric oxide is one of the smallest molecules involved in physiological functions in the body. It is seeks formation of chemical bonds with its targets.  Nitric oxide can exert its effects principally by two ways:

  • Direct
  • Indirect

Direct actions, as the name suggests, result from direct chemical interaction of NO with its targets e.g. with metal complexes, radical species. These actions occur at relatively low NO concentrations (<200 nM)

Indirect actions result from the effects of reactive nitrogen species (RNS) such as NO2 and N2O3. These reactive species are formed by the interaction of NO with superoxide or molecular oxygen. RNS are generally formed at relatively high NO concentrations (>400 nM)

Although it can be tempting for scientists to believe that RNS will always have deleterious effects and NO will have anabolic effects, this is not entirely true as certain RNS mediated actions mediate important signalling steps e.g. thiol oxidation and nitrosation of proteins mediate cell proliferation and survival, and apoptosis respectively.

  • Cells subjected to NO concentration between 10-30 nM were associated with cGMP dependent phosphorylation of ERK
  • Cells subjected to NO concentration between 30-60 nM were associated with Akt phosphorylation
  • Concentration nearing 100 nM resulted in stabilisation of hypoxia inducible factor-1
  • At nearly 400 nM NO, p53 can be modulated
  • >1μM NO, it nhibits mitochondrial respiration

 

Nitric oxide signaling, oxidative stress,  mitochondria, cell damage

Recent data suggests that other NO containing compounds such as S- or N-nitrosoproteins and iron-nitrosyl complexes can be reduced back to produce NO. These NO containing compounds can serve as storage and can reach distant tissues via blood circulation, remote from their place of origin. Hence NO can have both paracrine and ‘endocrine’ effects.

Intracellularly the oxidants present in the cytosol determine the amount of bioacitivity that NO performs. NO can travel roughly 100 microns from NOS enzymes where it is produced.

NO itself in low concentrations have protective action on mitochondrial signaling of cell death.

The aerobic cell was an advance in evolutionary development, but despite the energetic advantage of using oxygen, the associated toxicity of oxygen abundance required adaptive changes.

Oxidation-reduction reactions that are necessary for catabolic and synthetic reactions, can cumulatively damage the organism associated with cancer, cardiovascular disease, neurodegerative disease, and inflammatory overload.  The normal balance between production of pro-oxidant species and destruction by the antioxidant defenses is upset in favor of overproduction of the toxic species, which leads to oxidative stress and disease.

We reviewed the complex interactions and underlying regulatory balances/imbalances between the mechanism of vasorelaxation and vasoconstriction of vascular endothelium by way of nitric oxide (NO), prostacyclin, in response to oxidative stress and intimal injury.

Nitric oxide has a ubiquitous role in the regulation of glycolysis with a concomitant influence on mitochondrial function. The influence on mitochondrial function that is active in endothelium, platelets, vascular smooth muscle and neural cells and the resulting balance has a role in chronic inflammation, asthma, hypertension, sepsis and cancer.

Potential cytotoxic mediators of endothelial cell (EC) apoptosis include increased formation of reactive oxygen and nitrogen species (ROSRNS) during the atherosclerotic process. Nitric oxide (NO) has a biphasic action on oxidative cell killing with low concentrations protecting against cell death, whereas higher concentrations are cytotoxic.

ROS induces mitochondrial DNA damage in ECs, and this damage is accompanied by a decrease in mitochondrial RNA (mtRNA) transcripts, mitochondrial protein synthesis, and cellular ATP levels.

NO and circulatory diseases

Blood vessels arise from endothelial precursors that are thin, flat cells lining the inside of blood vessels forming a monolayer throughout the circulatory system. ECs are defined by specific cell surface markers that characterize their phenotype.

Scientists at the University of Helsinki, Finland, wanted to find out if there exists a rare vascular endothelial stem cell (VESC) population that is capable of producing very high numbers of endothelial daughter cells, and can lead to neovascular growth in adults.

VESCs discovered that reside at the blood vessel wall endothelium are a small population of CD117+ ECs capable of self-renewal.  These cells are capable of undergoing clonal expansion unlike the surrounding ECs that bear limited proliferating potential. A single VESC cell isolated from the endothelial population was able to generate functional blood vessels.

Among many important roles of Nitric oxide (NO), one of the key actions is to act as a vasodilator and maintain cardiovascular health. Induction of NO is regulated by signals in tissue as well as endothelium.

Chen et. al. (Med. Biol. Eng. Comp., 2011) developed a 3-D model consisting of two branched arterioles and nine capillaries surrounding the vessels. Their model not only takes into account of the 3-D volume, but also branching effects on blood flow.

The model indicates that wall shear stress changes depending upon the distribution of RBC in the microcirculations of blood vessels, lead to differential production of NO along the vascular network.

Endothelial dysfunction, the hallmark of which is reduced activity of endothelial cell derived nitric oxide (NO), is a key factor in developing atherosclerosis and cardiovascular disease. Vascular endothelial cells play a pivotal role in modulation of leukocyte and platelet adherence, thrombogenicity, anticoagulation, and vessel wall contraction and relaxation, so that endothelial dysfunction has become almost a synonym for vascular disease. A single layer of endothelial cells is the only constituent of capillaries, which differ from other vessels, which contain smooth muscle cells and adventitia. Capillaries directly mediate nutritional supply as well as gas exchange within all organs. The failure of the microcirculation leads to tissue apoptosis/necrosis.

Read Full Post »

Summary – Volume 4, Part 2: Translational Medicine in Cardiovascular Diseases


Summary – Volume 4, Part 2:  Translational Medicine in Cardiovascular Diseases

Author and Curator: Larry H Bernstein, MD, FCAP

 

We have covered a large amount of material that involves

  • the development,
  • application, and
  • validation of outcomes of medical and surgical procedures

that are based on translation of science from the laboratory to the bedside, improving the standards of medical practice at an accelerated pace in the last quarter century, and in the last decade.  Encouraging enabling developments have been:

1. The establishment of national and international outcomes databases for procedures by specialist medical societies

Stent Design and Thrombosis: Bifurcation Intervention, Drug Eluting Stents (DES) and Biodegrable Stents
Curator: Aviva Lev-Ari, PhD, RN
https://pharmaceuticalintelligence.com/2013/08/06/stent-design-and-thrombosis-bifurcation-intervention-drug-eluting-stents-des-and-biodegrable-stents/

On Devices and On Algorithms: Prediction of Arrhythmia after Cardiac Surgery and ECG Prediction of an Onset of Paroxysmal Atrial Fibrillation
Author, and Content Consultant to e-SERIES A: Cardiovascular Diseases: Justin Pearlman, MD, PhD, FACC
https://pharmaceuticalintelligence.com/2013/05/07/on-devices-and-on-algorithms-arrhythmia-after-cardiac-surgery-prediction-and-ecg-prediction-of-paroxysmal-atrial-fibrillation-onset/

Mitral Valve Repair: Who is a Patient Candidate for a Non-Ablative Fully Non-Invasive Procedure?
Author, and Content Consultant to e-SERIES A: Cardiovascular Diseases: Justin Pearlman, MD, PhD, FACC and Article Curator: Aviva Lev-Ari, PhD, RN
https://pharmaceuticalintelligence.com/2013/11/04/mitral-valve-repair-who-is-a-candidate-for-a-non-ablative-fully-non-invasive-procedure/

Cardiovascular Complications: Death from Reoperative Sternotomy after prior CABG, MVR, AVR, or Radiation; Complications of PCI; Sepsis from Cardiovascular Interventions
Author, Introduction and Summary: Justin D Pearlman, MD, PhD, FACC and Article Curator: Aviva Lev-Ari, PhD, RN
https://pharmaceuticalintelligence.com/2013/07/23/cardiovascular-complications-of-multiple-etiologies-repeat-sternotomy-post-cabg-or-avr-post-pci-pad-endoscopy-andor-resultant-of-systemic-sepsis/

Survivals Comparison of Coronary Artery Bypass Graft (CABG) and Percutaneous Coronary Intervention (PCI) /Coronary Angioplasty
Larry H. Bernstein, MD, Writer And Aviva Lev-Ari, PhD, RN, Curator
https://pharmaceuticalintelligence.com/2013/06/23/comparison-of-cardiothoracic-bypass-and-percutaneous-interventional-catheterization-survivals/

Revascularization: PCI, Prior History of PCI vs CABG
Curator: Aviva Lev-Ari, PhD, RN
https://pharmaceuticalintelligence.com/2013/04/25/revascularization-pci-prior-history-of-pci-vs-cabg/

Outcomes in High Cardiovascular Risk Patients: Prasugrel (Effient) vs. Clopidogrel (Plavix); Aliskiren (Tekturna) added to ACE or added to ARB
Reporter and Curator: Aviva Lev-Ari, PhD, RN
https://pharmaceuticalintelligence.com/2012/08/27/outcomes-in-high-cardiovascular-risk-patients-prasugrel-effient-vs-clopidogrel-plavix-aliskiren-tekturna-added-to-ace-or-added-to-arb/

Endovascular Lower-extremity Revascularization Effectiveness: Vascular Surgeons (VSs), Interventional Cardiologists (ICs) and Interventional Radiologists (IRs)
Curator: Aviva Lev-Ari, PhD, RN
https://pharmaceuticalintelligence.com/2012/08/13/coronary-artery-disease-medical-devices-solutions-from-first-in-man-stent-implantation-via-medical-ethical-dilemmas-to-drug-eluting-stents/

and more

2. The identification of problem areas, particularly in activation of the prothrombotic pathways, infection control to an extent, and targeting of pathways leading to progression or to arrythmogenic complications.

Cardiovascular Complications: Death from Reoperative Sternotomy after prior CABG, MVR, AVR, or Radiation; Complications of PCI; Sepsis from Cardiovascular Interventions Author, Introduction and Summary: Justin D Pearlman, MD, PhD, FACC and Article Curator: Aviva Lev-Ari, PhD, RN
https://pharmaceuticalintelligence.com/2013/07/23/cardiovascular-complications-of-multiple-etiologies-repeat-sternotomy-post-cabg-or-avr-post-pci-pad-endoscopy-andor-resultant-of-systemic-sepsis/

Anticoagulation genotype guided dosing
Larry H. Bernstein, MD, FCAP, Author and Curator
https://pharmaceuticalintelligence.com/2013/12/08/anticoagulation-genotype-guided-dosing/

Stent Design and Thrombosis: Bifurcation Intervention, Drug Eluting Stents (DES) and Biodegrable Stents
Curator: Aviva Lev-Ari, PhD, RN
https://pharmaceuticalintelligence.com/2013/08/06/stent-design-and-thrombosis-bifurcation-intervention-drug-eluting-stents-des-and-biodegrable-stents/

The Effects of Aprotinin on Endothelial Cell Coagulant Biology
Co-Author (Kamran Baig, MBBS, James Jaggers, MD, Jeffrey H. Lawson, MD, PhD) and Curator
https://pharmaceuticalintelligence.com/2013/07/20/the-effects-of-aprotinin-on-endothelial-cell-coagulant-biology/

Outcomes in High Cardiovascular Risk Patients: Prasugrel (Effient) vs. Clopidogrel (Plavix); Aliskiren (Tekturna) added to ACE or added to ARB
Reporter and Curator: Aviva Lev-Ari, PhD, RN
https://pharmaceuticalintelligence.com/2012/08/27/outcomes-in-high-cardiovascular-risk-patients-prasugrel-effient-vs-clopidogrel-plavix-aliskiren-tekturna-added-to-ace-or-added-to-arb/

Pharmacogenomics – A New Method for Druggability  Author and Curator: Demet Sag, PhD
https://pharmaceuticalintelligence.com/2014/04/28/pharmacogenomics-a-new-method-for-druggability/

Advanced Topics in Sepsis and the Cardiovascular System at its End Stage    Author: Larry H Bernstein, MD, FCAP
https://pharmaceuticalintelligence.com/2013/08/18/advanced-topics-in-Sepsis-and-the-Cardiovascular-System-at-its-End-Stage/

3. Development of procedures that use a safer materials in vascular management.

Stent Design and Thrombosis: Bifurcation Intervention, Drug Eluting Stents (DES) and Biodegrable Stents
Curator: Aviva Lev-Ari, PhD, RN
https://pharmaceuticalintelligence.com/2013/08/06/stent-design-and-thrombosis-bifurcation-intervention-drug-eluting-stents-des-and-biodegrable-stents/

Biomaterials Technology: Models of Tissue Engineering for Reperfusion and Implantable Devices for Revascularization
Author and Curator: Larry H Bernstein, MD, FACP and Curator: Aviva Lev-Ari, PhD, RN
https://pharmaceuticalintelligence.com/2013/05/05/bioengineering-of-vascular-and-tissue-models/

Vascular Repair: Stents and Biologically Active Implants
Author and Curator: Larry H Bernstein, MD, FACP and Curator: Aviva Lev-Ari, RN, PhD
https://pharmaceuticalintelligence.com/2013/05/04/stents-biologically-active-implants-and-vascular-repair/

Drug Eluting Stents: On MIT’s Edelman Lab’s Contributions to Vascular Biology and its Pioneering Research on DES
Author: Larry H Bernstein, MD, FACP and Curator: Aviva Lev-Ari, PhD, RN
http://PharmaceuticalIntelligence.com/2013/04/25/Contributions-to-vascular-biology/

MedTech & Medical Devices for Cardiovascular Repair – Curations by Aviva Lev-Ari, PhD, RN
https://pharmaceuticalintelligence.com/2014/04/17/medtech-medical-devices-for-cardiovascular-repair-curation-by-aviva-lev-ari-phd-rn/

4. Discrimination of cases presenting for treatment based on qualifications for medical versus surgical intervention.

Treatment Options for Left Ventricular Failure – Temporary Circulatory Support: Intra-aortic balloon pump (IABP) – Impella Recover LD/LP 5.0 and 2.5, Pump Catheters (Non-surgical) vs Bridge Therapy: Percutaneous Left Ventricular Assist Devices (pLVADs) and LVADs (Surgical)
Author: Larry H Bernstein, MD, FCAP And Curator: Justin D Pearlman, MD, PhD, FACC
https://pharmaceuticalintelligence.com/2013/07/17/treatment-options-for-left-ventricular-failure-temporary-circulatory-support-intra-aortic-balloon-pump-iabp-impella-recover-ldlp-5-0-and-2-5-pump-catheters-non-surgical-vs-bridge-therapy/

Coronary Reperfusion Therapies: CABG vs PCI – Mayo Clinic preprocedure Risk Score (MCRS) for Prediction of in-Hospital Mortality after CABG or PCI
Writer and Curator: Larry H. Bernstein, MD, FCAP and Curator: Aviva Lev-Ari, PhD, RN
https://pharmaceuticalintelligence.com/2013/06/30/mayo-risk-score-for-percutaneous-coronary-intervention/

ACC/AHA Guidelines for Coronary Artery Bypass Graft Surgery Reporter: Aviva Lev-Ari, PhD, RN
https://pharmaceuticalintelligence.com/2013/11/05/accaha-guidelines-for-coronary-artery-bypass-graft-surgery/

Mitral Valve Repair: Who is a Patient Candidate for a Non-Ablative Fully Non-Invasive Procedure?
Author, and Content Consultant to e-SERIES A: Cardiovascular Diseases: Justin Pearlman, MD, PhD, FACC and Article Curator: Aviva Lev-Ari, PhD, RN
https://pharmaceuticalintelligence.com/2013/11/04/mitral-valve-repair-who-is-a-candidate-for-a-non-ablative-fully-non-invasive-procedure/ 

5.  This has become possible because of the advances in our knowledge of key related pathogenetic mechanisms involving gene expression and cellular regulation of complex mechanisms.

What is the key method to harness Inflammation to close the doors for many complex diseases?
Author and Curator: Larry H Bernstein, MD, FCAP
https://pharmaceuticalintelligence.com/2014/03/21/what-is-the-key-method-to-harness-inflammation-to-close-the-doors-for-many-complex-diseases/

CVD Prevention and Evaluation of Cardiovascular Imaging Modalities: Coronary Calcium Score by CT Scan Screening to justify or not the Use of Statin
Curator: Aviva Lev-Ari, PhD, RN
https://pharmaceuticalintelligence.com/2014/03/03/cvd-prevention-and-evaluation-of-cardiovascular-imaging-modalities-coronary-calcium-score-by-ct-scan-screening-to-justify-or-not-the-use-of-statin/

Richard Lifton, MD, PhD of Yale University and Howard Hughes Medical Institute: Recipient of 2014 Breakthrough Prizes Awarded in Life Sciences for the Discovery of Genes and Biochemical Mechanisms that cause Hypertension
Curator: Aviva Lev-Ari, PhD, RN
https://pharmaceuticalintelligence.com/2014/03/03/richard-lifton-md-phd-of-yale-university-and-howard-hughes-medical-institute-recipient-of-2014-breakthrough-prizes-awarded-in-life-sciences-for-the-discovery-of-genes-and-biochemical-mechanisms-tha/

Pathophysiological Effects of Diabetes on Ischemic-Cardiovascular Disease and on Chronic Obstructive Pulmonary Disease (COPD)
Curator:  Larry H. Bernstein, MD, FCAP
https://pharmaceuticalintelligence.com/2014/01/15/pathophysiological-effects-of-diabetes-on-ischemic-cardiovascular-disease-and-on-chronic-obstructive-pulmonary-disease-copd/

Atherosclerosis Independence: Genetic Polymorphisms of Ion Channels Role in the Pathogenesis of Coronary Microvascular Dysfunction and Myocardial Ischemia (Coronary Artery Disease (CAD))
Reviewer and Co-Curator: Larry H Bernstein, MD, CAP and Curator: Aviva Lev-Ari, PhD, RN
https://pharmaceuticalintelligence.com/2013/12/21/genetic-polymorphisms-of-ion-channels-have-a-role-in-the-pathogenesis-of-coronary-microvascular-dysfunction-and-ischemic-heart-disease/

Notable Contributions to Regenerative Cardiology  Author and Curator: Larry H Bernstein, MD, FCAP and Article Commissioner: Aviva Lev-Ari, PhD, RD
https://pharmaceuticalintelligence.com/2013/10/20/notable-contributions-to-regenerative-cardiology/

As noted in the introduction, any of the material can be found and reviewed by content, and the eTOC is identified in attached:

http://wp.me/p2xfv8-1W

 

This completes what has been presented in Part 2, Vol 4 , and supporting references for the main points that are found in the Leaders in Pharmaceutical Intelligence Cardiovascular book.  Part 1 was concerned with Posttranslational Modification of Proteins, vital for understanding cellular regulation and dysregulation.  Part 2 was concerned with Translational Medical Therapeutics, the efficacy of medical and surgical decisions based on bringing the knowledge gained from the laboratory, and from clinical trials into the realm opf best practice.  The time for this to occur in practice in the past has been through roughly a generation of physicians.  That was in part related to the busy workload of physicians, and inability to easily access specialty literature as the volume and complexity increased.  This had an effect of making access of a family to a primary care provider through a lifetime less likely than the period post WWII into the 1980s.

However, the growth of knowledge has accelerated in the specialties since the 1980’s so that the use of physician referral in time became a concern about the cost of medical care.  This is not the place for or a matter for discussion here.  It is also true that the scientific advances and improvements in available technology have had a great impact on medical outcomes.  The only unrelated issue is that of healthcare delivery, which is not up to the standard set by serial advances in therapeutics, accompanied by high cost due to development costs, marketing costs, and development of drug resistance.

I shall identify continuing developments in cardiovascular diagnostics, therapeutics, and bioengineering that is and has been emerging.

1. Mechanisms of disease

REPORT: Mapping the Cellular Response to Small Molecules Using Chemogenomic Fitness Signatures 

Science 11 April 2014:
Vol. 344 no. 6180 pp. 208-211
http://dx.doi.org/10.1126/science.1250217

Abstract: Genome-wide characterization of the in vivo cellular response to perturbation is fundamental to understanding how cells survive stress. Identifying the proteins and pathways perturbed by small molecules affects biology and medicine by revealing the mechanisms of drug action. We used a yeast chemogenomics platform that quantifies the requirement for each gene for resistance to a compound in vivo to profile 3250 small molecules in a systematic and unbiased manner. We identified 317 compounds that specifically perturb the function of 121 genes and characterized the mechanism of specific compounds. Global analysis revealed that the cellular response to small molecules is limited and described by a network of 45 major chemogenomic signatures. Our results provide a resource for the discovery of functional interactions among genes, chemicals, and biological processes.

Yeasty HIPHOP

Laura Zahn
Sci. Signal. 15 April 2014; 7(321): ec103.   http://dx.doi.org/10.1126/scisignal.2005362

In order to identify how chemical compounds target genes and affect the physiology of the cell, tests of the perturbations that occur when treated with a range of pharmacological chemicals are required. By examining the haploinsufficiency profiling (HIP) and homozygous profiling (HOP) chemogenomic platforms, Lee et al.(p. 208) analyzed the response of yeast to thousands of different small molecules, with genetic, proteomic, and bioinformatic analyses. Over 300 compounds were identified that targeted 121 genes within 45 cellular response signature networks. These networks were used to extrapolate the likely effects of related chemicals, their impact upon genetic pathways, and to identify putative gene functions

Key Heart Failure Culprit Discovered

A team of cardiovascular researchers from the Cardiovascular Research Center at Icahn School of Medicine at Mount Sinai, Sanford-Burnham Medical Research Institute, and University of California, San Diego have identified a small, but powerful, new player in thIe onset and progression of heart failure. Their findings, published in the journal Nature  on March 12, also show how they successfully blocked the newly discovered culprit.
Investigators identified a tiny piece of RNA called miR-25 that blocks a gene known as SERCA2a, which regulates the flow of calcium within heart muscle cells. Decreased SERCA2a activity is one of the main causes of poor contraction of the heart and enlargement of heart muscle cells leading to heart failure.

Using a functional screening system developed by researchers at Sanford-Burnham, the research team discovered miR-25 acts pathologically in patients suffering from heart failure, delaying proper calcium uptake in heart muscle cells. According to co-lead study authors Christine Wahlquist and Dr. Agustin Rojas Muñoz, developers of the approach and researchers in Mercola’s lab at Sanford-Burnham, they used high-throughput robotics to sift through the entire genome for microRNAs involved in heart muscle dysfunction.

Subsequently, the researchers at the Cardiovascular Research Center at Icahn School of Medicine at Mount Sinai found that injecting a small piece of RNA to inhibit the effects of miR-25 dramatically halted heart failure progression in mice. In addition, it also improved their cardiac function and survival.

“In this study, we have not only identified one of the key cellular processes leading to heart failure, but have also demonstrated the therapeutic potential of blocking this process,” says co-lead study author Dr. Dongtak Jeong, a post-doctoral fellow at the Cardiovascular Research Center at Icahn School of  Medicine at Mount Sinai in the laboratory of the study’s co-senior author Dr. Roger J. Hajjar.

Publication: Inhibition of miR-25 improves cardiac contractility in the failing heart.Christine Wahlquist, Dongtak Jeong, Agustin Rojas-Muñoz, Changwon Kho, Ahyoung Lee, Shinichi Mitsuyama, Alain Van Mil, Woo Jin Park, Joost P. G. Sluijter, Pieter A. F. Doevendans, Roger J. :  Hajjar & Mark Mercola.     Nature (March 2014)    http://www.nature.com/nature/journal/vaop/ncurrent/full/nature13073.html

 

“Junk” DNA Tied to Heart Failure

Deep RNA Sequencing Reveals Dynamic Regulation of Myocardial Noncoding RNAs in Failing Human Heart and Remodeling With Mechanical Circulatory Support

Yang KC, Yamada KA, Patel AY, Topkara VK, George I, et al.
Circulation 2014;  129(9):1009-21.
http://dx.doi.org/10.1161/CIRCULATIONAHA.113.003863              http://circ.ahajournals.org/…/CIRCULATIONAHA.113.003863.full

The myocardial transcriptome is dynamically regulated in advanced heart failure and after LVAD support. The expression profiles of lncRNAs, but not mRNAs or miRNAs, can discriminate failing hearts of different pathologies and are markedly altered in response to LVAD support. These results suggest an important role for lncRNAs in the pathogenesis of heart failure and in reverse remodeling observed with mechanical support.

Junk DNA was long thought to have no important role in heredity or disease because it doesn’t code for proteins. But emerging research in recent years has revealed that many of these sections of the genome produce noncoding RNA molecules that still have important functions in the body. They come in a variety of forms, some more widely studied than others. Of these, about 90% are called long noncoding RNAs (lncRNAs), and exploration of their roles in health and disease is just beginning.

The Washington University group performed a comprehensive analysis of all RNA molecules expressed in the human heart. The researchers studied nonfailing hearts and failing hearts before and after patients received pump support from left ventricular assist devices (LVAD). The LVADs increased each heart’s pumping capacity while patients waited for heart transplants.

In their study, the researchers found that unlike other RNA molecules, expression patterns of long noncoding RNAs could distinguish between two major types of heart failure and between failing hearts before and after they received LVAD support.

“The myocardial transcriptome is dynamically regulated in advanced heart failure and after LVAD support. The expression profiles of lncRNAs, but not mRNAs or miRNAs, can discriminate failing hearts of different pathologies and are markedly altered in response to LVAD support,” wrote the researchers. “These results suggest an important role for lncRNAs in the pathogenesis of heart failure and in reverse remodeling observed with mechanical support.”

‘Junk’ Genome Regions Linked to Heart Failure

In a recent issue of the journal Circulation, Washington University investigators report results from the first comprehensive analysis of all RNA molecules expressed in the human heart. The researchers studied nonfailing hearts and failing hearts before and after patients received pump support from left ventricular assist devices (LVAD). The LVADs increased each heart’s pumping capacity while patients waited for heart transplants.

“We took an unbiased approach to investigating which types of RNA might be linked to heart failure,” said senior author Jeanne Nerbonne, the Alumni Endowed Professor of Molecular Biology and Pharmacology. “We were surprised to find that long noncoding RNAs stood out.

In the new study, the investigators found that unlike other RNA molecules, expression patterns of long noncoding RNAs could distinguish between two major types of heart failure and between failing hearts before and after they received LVAD support.

“We don’t know whether these changes in long noncoding RNAs are a cause or an effect of heart failure,” Nerbonne said. “But it seems likely they play some role in coordinating the regulation of multiple genes involved in heart function.”

Nerbonne pointed out that all types of RNA molecules they examined could make the obvious distinction: telling the difference between failing and nonfailing hearts. But only expression of the long noncoding RNAs was measurably different between heart failure associated with a heart attack (ischemic) and heart failure without the obvious trigger of blocked arteries (nonischemic). Similarly, only long noncoding RNAs significantly changed expression patterns after implantation of left ventricular assist devices.

Comment

Decoding the noncoding transcripts in human heart failure

Xiao XG, Touma M, Wang Y
Circulation. 2014; 129(9): 958960,  http://dx.doi.org/10.1161/CIRCULATIONAHA.114.007548 

Heart failure is a complex disease with a broad spectrum of pathological features. Despite significant advancement in clinical diagnosis through improved imaging modalities and hemodynamic approaches, reliable molecular signatures for better differential diagnosis and better monitoring of heart failure progression remain elusive. The few known clinical biomarkers for heart failure, such as plasma brain natriuretic peptide and troponin, have been shown to have limited use in defining the cause or prognosis of the disease.1,2 Consequently, current clinical identification and classification of heart failure remain descriptive, mostly based on functional and morphological parameters. Therefore, defining the pathogenic mechanisms for hypertrophic versus dilated or ischemic versus nonischemic cardiomyopathies in the failing heart remain a major challenge to both basic science and clinic researchers. In recent years, mechanical circulatory support using left ventricular assist devices (LVADs) has assumed a growing role in the care of patients with end-stage heart failure.3 During the earlier years of LVAD application as a bridge to transplant, it became evident that some patients exhibit substantial recovery of ventricular function, structure, and electric properties.4 This led to the recognition that reverse remodeling is potentially an achievable therapeutic goal using LVADs. However, the underlying mechanism for the reverse remodeling in the LVAD-treated hearts is unclear, and its discovery would likely hold great promise to halt or even reverse the progression of heart failure.

 

Efficacy and Safety of Dabigatran Compared With Warfarin in Relation to Baseline Renal Function in Patients With Atrial Fibrillation: A RE-LY (Randomized Evaluation of Long-term Anticoagulation Therapy) Trial Analysis

Circulation. 2014; 129: 951-952     http://dx.doi.org/10.1161/​CIR.0000000000000022

In patients with atrial fibrillation, impaired renal function is associated with a higher risk of thromboembolic events and major bleeding. Oral anticoagulation with vitamin K antagonists reduces thromboembolic events but raises the risk of bleeding. The new oral anticoagulant dabigatran has 80% renal elimination, and its efficacy and safety might, therefore, be related to renal function. In this prespecified analysis from the Randomized Evaluation of Long-Term Anticoagulant Therapy (RELY) trial, outcomes with dabigatran versus warfarin were evaluated in relation to 4 estimates of renal function, that is, equations based on creatinine levels (Cockcroft-Gault, Modification of Diet in Renal Disease (MDRD), Chronic Kidney Disease Epidemiology Collaboration [CKD-EPI]) and cystatin C. The rates of stroke or systemic embolism were lower with dabigatran 150 mg and similar with 110 mg twice daily irrespective of renal function. Rates of major bleeding were lower with dabigatran 110 mg and similar with 150 mg twice daily across the entire range of renal function. However, when the CKD-EPI or MDRD equations were used, there was a significantly greater relative reduction in major bleeding with both doses of dabigatran than with warfarin in patients with estimated glomerular filtration rate ≥80 mL/min. These findings show that dabigatran can be used with the same efficacy and adequate safety in patients with a wide range of renal function and that a more accurate estimate of renal function might be useful for improved tailoring of anticoagulant treatment in patients with atrial fibrillation and an increased risk of stroke.

Aldosterone Regulates MicroRNAs in the Cortical Collecting Duct to Alter Sodium Transport.

Robert S Edinger, Claudia Coronnello, Andrew J Bodnar, William A Laframboise, Panayiotis V Benos, Jacqueline Ho, John P Johnson, Michael B Butterworth

Journal of the American Society of Nephrology (Impact Factor: 8.99). 04/2014;     http://dx. DO.org/I:10.1681/ASN.2013090931

Source: PubMed

ABSTRACT A role for microRNAs (miRs) in the physiologic regulation of sodium transport in the kidney has not been established. In this study, we investigated the potential of aldosterone to alter miR expression in mouse cortical collecting duct (mCCD) epithelial cells. Microarray studies demonstrated the regulation of miR expression by aldosterone in both cultured mCCD and isolated primary distal nephron principal cells.

Aldosterone regulation of the most significantly downregulated miRs, mmu-miR-335-3p, mmu-miR-290-5p, and mmu-miR-1983 was confirmed by quantitative RT-PCR. Reducing the expression of these miRs separately or in combination increased epithelial sodium channel (ENaC)-mediated sodium transport in mCCD cells, without mineralocorticoid supplementation. Artificially increasing the expression of these miRs by transfection with plasmid precursors or miR mimic constructs blunted aldosterone stimulation of ENaC transport.

Using a newly developed computational approach, termed ComiR, we predicted potential gene targets for the aldosterone-regulated miRs and confirmed ankyrin 3 (Ank3) as a novel aldosterone and miR-regulated protein.

A dual-luciferase assay demonstrated direct binding of the miRs with the Ank3-3′ untranslated region. Overexpression of Ank3 increased and depletion of Ank3 decreased ENaC-mediated sodium transport in mCCD cells. These findings implicate miRs as intermediaries in aldosterone signaling in principal cells of the distal kidney nephron.

 

2. Diagnostic Biomarker Status

A prospective study of the impact of serial troponin measurements on the diagnosis of myocardial infarction and hospital and 6-month mortality in patients admitted to ICU with non-cardiac diagnoses.

Marlies Ostermann, Jessica Lo, Michael Toolan, Emma Tuddenham, Barnaby Sanderson, Katie Lei, John Smith, Anna Griffiths, Ian Webb, James Coutts, John hambers, Paul Collinson, Janet Peacock, David Bennett, David Treacher

Critical care (London, England) (Impact Factor: 4.72). 04/2014; 18(2):R62.   http://dx.doi.org/:10.1186/cc13818

Source: PubMed

ABSTRACT Troponin T (cTnT) elevation is common in patients in the Intensive Care Unit (ICU) and associated with morbidity and mortality. Our aim was to determine the epidemiology of raised cTnT levels and contemporaneous electrocardiogram (ECG) changes suggesting myocardial infarction (MI) in ICU patients admitted for non-cardiac reasons.
cTnT and ECGs were recorded daily during week 1 and on alternate days during week 2 until discharge from ICU or death. ECGs were interpreted independently for the presence of ischaemic changes. Patients were classified into 4 groups: (i) definite MI (cTnT >=15 ng/L and contemporaneous changes of MI on ECG), (ii) possible MI (cTnT >=15 ng/L and contemporaneous ischaemic changes on ECG), (iii) troponin rise alone (cTnT >=15 ng/L), or (iv) normal. Medical notes were screened independently by two ICU clinicians for evidence that the clinical teams had considered a cardiac event.
Data from 144 patients were analysed [42% female; mean age 61.9 (SD 16.9)]. 121 patients (84%) had at least one cTnT level >=15 ng/L. A total of 20 patients (14%) had a definite MI, 27% had a possible MI, 43% had a cTNT rise without contemporaneous ECG changes, and 16% had no cTNT rise. ICU, hospital and 180 day mortality were significantly higher in patients with a definite or possible MI.Only 20% of definite MIs were recognised by the clinical team. There was no significant difference in mortality between recognised and non-recognised events.At time of cTNT rise, 100 patients (70%) were septic and 58% were on vasopressors. Patients who were septic when cTNT was elevated had an ICU mortality of 28% compared to 9% in patients without sepsis. ICU mortality of patients who were on vasopressors at time of cTNT elevation was 37% compared to 1.7% in patients not on vasopressors.
The majority of critically ill patients (84%) had a cTnT rise and 41% met criteria for a possible or definite MI of whom only 20% were recognised clinically. Mortality up to 180 days was higher in patients with a cTnT rise.

 

Prognostic performance of high-sensitivity cardiac troponin T kinetic changes adjusted for elevated admission values and the GRACE score in an unselected emergency department population.

Moritz BienerMatthias MuellerMehrshad VafaieAllan S JaffeHugo A Katus,Evangelos Giannitsis

Clinica chimica acta; international journal of clinical chemistry (Impact Factor: 2.54). 04/2014;   http://dx.doi.org/10.1016/j.cca.2014.04.007

Source: PubMed

ABSTRACT To test the prognostic performance of rising and falling kinetic changes of high-sensitivity cardiac troponin T (hs-cTnT) and the GRACE score.
Rising and falling hs-cTnT changes in an unselected emergency department population were compared.
635 patients with a hs-cTnT >99th percentile admission value were enrolled. Of these, 572 patients qualified for evaluation with rising patterns (n=254, 44.4%), falling patterns (n=224, 39.2%), or falling patterns following an initial rise (n=94, 16.4%). During 407days of follow-up, we observed 74 deaths, 17 recurrent AMI, and 79 subjects with a composite of death/AMI. Admission values >14ng/L were associated with a higher rate of adverse outcomes (OR, 95%CI:death:12.6, 1.8-92.1, p=0.01, death/AMI:6.7, 1.6-27.9, p=0.01). Neither rising nor falling changes increased the AUC of baseline values (AUC: rising 0.562 vs 0.561, p=ns, falling: 0.533 vs 0.575, p=ns). A GRACE score ≥140 points indicated a higher risk of death (OR, 95%CI: 3.14, 1.84-5.36), AMI (OR,95%CI: 1.56, 0.59-4.17), or death/AMI (OR, 95%CI: 2.49, 1.51-4.11). Hs-cTnT changes did not improve prognostic performance of a GRACE score ≥140 points (AUC, 95%CI: death: 0.635, 0.570-0.701 vs. 0.560, 0.470-0.649 p=ns, AMI: 0.555, 0.418-0.693 vs. 0.603, 0.424-0.782, p=ns, death/AMI: 0.610, 0.545-0.676 vs. 0.538, 0.454-0.622, p=ns). Coronary angiography was performed earlier in patients with rising than with falling kinetics (median, IQR [hours]:13.7, 5.5-28.0 vs. 20.8, 6.3-59.0, p=0.01).
Neither rising nor falling hs-cTnT changes improve prognostic performance of elevated hs-cTnT admission values or the GRACE score. However, rising values are more likely associated with the decision for earlier invasive strategy.

 

Troponin assays for the diagnosis of myocardial infarction and acute coronary syndrome: where do we stand?

Arie Eisenman

ABSTRACT: Under normal circumstances, most intracellular troponin is part of the muscle contractile apparatus, and only a small percentage (< 2-8%) is free in the cytoplasm. The presence of a cardiac-specific troponin in the circulation at levels above normal is good evidence of damage to cardiac muscle cells, such as myocardial infarction, myocarditis, trauma, unstable angina, cardiac surgery or other cardiac procedures. Troponins are released as complexes leading to various cut-off values depending on the assay used. This makes them very sensitive and specific indicators of cardiac injury. As with other cardiac markers, observation of a rise and fall in troponin levels in the appropriate time-frame increases the diagnostic specificity for acute myocardial infarction. They start to rise approximately 4-6 h after the onset of acute myocardial infarction and peak at approximately 24 h, as is the case with creatine kinase-MB. They remain elevated for 7-10 days giving a longer diagnostic window than creatine kinase. Although the diagnosis of various types of acute coronary syndrome remains a clinical-based diagnosis, the use of troponin levels contributes to their classification. This Editorial elaborates on the nature of troponin, its classification, clinical use and importance, as well as comparing it with other currently available cardiac markers.

Expert Review of Cardiovascular Therapy 07/2006; 4(4):509-14.   http://dx.doi.org/:10.1586/14779072.4.4.509 

 

Impact of redefining acute myocardial infarction on incidence, management and reimbursement rate of acute coronary syndromes.

Carísi A Polanczyk, Samir Schneid, Betina V Imhof, Mariana Furtado, Carolina Pithan, Luis E Rohde, Jorge P Ribeiro

ABSTRACT: Although redefinition for acute myocardial infarction (AMI) has been proposed few years ago, to date it has not been universally adopted by many institutions. The purpose of this study is to evaluate the diagnostic, prognostic and economical impact of the new diagnostic criteria for AMI. Patients consecutively admitted to the emergency department with suspected acute coronary syndromes were enrolled in this study. Troponin T (cTnT) was measured in samples collected for routine CK-MB analyses and results were not available to physicians. Patients without AMI by traditional criteria and cTnT > or = 0.035 ng/mL were coded as redefined AMI. Clinical outcomes were hospital death, major cardiac events and revascularization procedures. In-hospital management and reimbursement rates were also analyzed. Among 363 patients, 59 (16%) patients had AMI by conventional criteria, whereas additional 75 (21%) had redefined AMI, an increase of 127% in the incidence. Patients with redefined AMI were significantly older, more frequently male, with atypical chest pain and more risk factors. In multivariate analysis, redefined AMI was associated with 3.1 fold higher hospital death (95% CI: 0.6-14) and a 5.6 fold more cardiac events (95% CI: 2.1-15) compared to those without AMI. From hospital perspective, based on DRGs payment system, adoption of AMI redefinition would increase 12% the reimbursement rate [3552 Int dollars per 100 patients evaluated]. The redefined criteria result in a substantial increase in AMI cases, and allow identification of high-risk patients. Efforts should be made to reinforce the adoption of AMI redefinition, which may result in more qualified and efficient management of ACS.

International Journal of Cardiology 03/2006; 107(2):180-7. · 5.51 Impact Factor   http://www.sciencedirect.com/science/article/pii/S0167527305005279

 

3. Biomedical Engineerin3g

Safety and Efficacy of an Injectable Extracellular Matrix Hydrogel for Treating Myocardial Infarction 

Sonya B. Seif-Naraghi, Jennifer M. Singelyn, Michael A. Salvatore,  et al.
Sci Transl Med 20 February 2013 5:173ra25  http://dx.doi.org/10.1126/scitranslmed.3005503

Acellular biomaterials can stimulate the local environment to repair tissues without the regulatory and scientific challenges of cell-based therapies. A greater understanding of the mechanisms of such endogenous tissue repair is furthering the design and application of these biomaterials. We discuss recent progress in acellular materials for tissue repair, using cartilage and cardiac tissues as examples of application with substantial intrinsic hurdles, but where human translation is now occurring.

 Acellular Biomaterials: An Evolving Alternative to Cell-Based Therapies

J. A. Burdick, R. L. Mauck, J. H. Gorman, R. C. Gorman,
Sci. Transl. Med. 2013; 5, (176): 176 ps4    http://stm.sciencemag.org/content/5/176/176ps4

Acellular biomaterials can stimulate the local environment to repair tissues without the regulatory and scientific challenges of cell-based therapies. A greater understanding of the mechanisms of such endogenous tissue repair is furthering the design and application of these biomaterials. We discuss recent progress in acellular materials for tissue repair, using cartilage and cardiac tissues as examples of applications with substantial intrinsic hurdles, but where human translation is now occurring.


Instructive Nanofiber Scaffolds with VEGF Create a Microenvironment for Arteriogenesis and Cardiac Repair

Yi-Dong Lin, Chwan-Yau Luo, Yu-Ning Hu, Ming-Long Yeh, Ying-Chang Hsueh, Min-Yao Chang, et al.
Sci Transl Med 8 August 2012; 4(146):ra109.   http://dx.doi.org/ 10.1126/scitranslmed.3003841

Angiogenic therapy is a promising approach for tissue repair and regeneration. However, recent clinical trials with protein delivery or gene therapy to promote angiogenesis have failed to provide therapeutic effects. A key factor for achieving effective revascularization is the durability of the microvasculature and the formation of new arterial vessels. Accordingly, we carried out experiments to test whether intramyocardial injection of self-assembling peptide nanofibers (NFs) combined with vascular endothelial growth factor (VEGF) could create an intramyocardial microenvironment with prolonged VEGF release to improve post-infarct neovascularization in rats. Our data showed that when injected with NF, VEGF delivery was sustained within the myocardium for up to 14 days, and the side effects of systemic edema and proteinuria were significantly reduced to the same level as that of control. NF/VEGF injection significantly improved angiogenesis, arteriogenesis, and cardiac performance 28 days after myocardial infarction. NF/VEGF injection not only allowed controlled local delivery but also transformed the injected site into a favorable microenvironment that recruited endogenous myofibroblasts and helped achieve effective revascularization. The engineered vascular niche further attracted a new population of cardiomyocyte-like cells to home to the injected sites, suggesting cardiomyocyte regeneration. Follow-up studies in pigs also revealed healing benefits consistent with observations in rats. In summary, this study demonstrates a new strategy for cardiovascular repair with potential for future clinical translation.

Manufacturing Challenges in Regenerative Medicine

I. Martin, P. J. Simmons, D. F. Williams.
Sci. Transl. Med. 2014; 6(232): fs16.   http://dx.doi.org/10.1126/scitranslmed.3008558

Along with scientific and regulatory issues, the translation of cell and tissue therapies in the routine clinical practice needs to address standardization and cost-effectiveness through the definition of suitable manufacturing paradigms.

 

 

 

Read Full Post »

Older Posts »