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The Dalio Institute for Cardiovascular Imaging at NewYork-Presbyterian Hospital combines research, clinical care and education to uncover new answers about preventing heart disease. A joint NewYork-Presbyterian Hospital and Weill Cornell Medicine venture, the institute employs a multidisciplinary, multimodality approach to the detection and treatment of heart disease. Directed by Dr. James K. Min, the institute’s mission is to innovate, integrate and educate, goals that will be achieved through cutting-edge research, transformations of current clinical paradigms and dissemination of knowledge.
Rooted in the central role of imaging techniques to better diagnose cardiovascular disease, the institute not only uses state-of-the-art tools such as MRI, CT and PET scanners, but also focuses on the development of novel next-generation technologies and diagnostic tests. Applying a team-based approach that draws on the expertise of physicians and scientists in radiology, cardiology, genetics, proteomics, and computational biology, the institute’s primary research initiative is to identify the specific coronary artery lesion that is responsible for heart attacks or sudden cardiac deaths.
The Dalio Institute uses imaging technologies in conjunction with other cutting-edge diagnostic tests, including blood markers of inflammation, protein expression and metabolism. The clinical program serves patients in the outpatient and inpatient setting, as well as in the emergency department. Three specific initiatives within the clinical program emphasize early identification of heart disease in women, ethnic minorities and young patients with a family history of premature heart disease.
Based on your medical history, we can use calculators to estimate your risk of having a cardiovascular event over time. Risk calculators use various factors including age, sex, and race, in addition to “traditional” cardiac risk factors such as smoking, diabetes, high cholesterol and high blood pressure. Our practice uses several common risk calculators. It is important to emphasize that risk calculators may be imperfect, especially in patients with unique risk factors. These might include a family history of early heart disease or a chronic inflammatory disorder. Therefore, it may be beneficial to consider a full cardiovascular assessment to explore your personal risk and strategies to reduce it.
Risk calculators may be of interest to you, but we caution that the results should be interpreted and reviewed by a trained clinical provider.
Your cardiovascular risk assessment at HeartHealth always begins with a detailed medical history and physical exam. The physical exam is often not able to fully diagnose problems, nor is it ever able to diagnose coronary artery disease or calcification. We therefore offer the most up-to-date noninvasive imaging studies to visualize the heart muscle, valves, blood flow and coronary arteries. We have state-of-the-art equipment and world-renowned experts to interpret these studies.
All of the following will be offered at HeartHealth (Click on the test name to view more information):
Cardiac Computed Tomography Angiography (CTA)
Cardiac Magnetic Resonance Imaging (MRI)
Cardiac PET/CT
Echocardiogram/Doppler Transthoracic
Exercise Electrocardiogram or ETT (Exercise Treadmill Test)
A Program of the Dalio Institute of Cardiovascular Imaging
at the NewYork-Presbyterian Hospital
1305 York Avenue, 8th Floor
New York, NY 10021 Map ThisP: (646) 962-4278 (HART)F: (646) 962-0188
Funded by a $20 million gift from the Dalio Foundation, the institute will combine research, clinical care, and education to uncover new answers about preventing heart disease
NEW YORK – To help reduce the burden of cardiovascular disease, the nation’s leading killer, NewYork-Presbyterian Hospital and Weill Cornell Medical College have created the Dalio Institute of Cardiovascular Imaging. Raymond T. Dalio, a life trustee of NewYork-Presbyterian Hospital, has made a gift of $20 million through his Dalio Foundation in support of the institute.
The Dalio Institute of Cardiovascular Imaging will employ a multidisciplinary, multimodality approach to the detection and treatment of heart disease, with a focus on finding new answers about prevention of heart disease in at-risk individuals and ultimately save lives. Its mission is to innovate, integrate, and educate, goals that will be achieved through cutting-edge research, transformations of current clinical paradigms, and dissemination of knowledge. Dr. James K. Min, an expert in cardiovascular imaging and a physician-scientist who has led several large-scale multicenter clinical trials, has been appointed director of the Dalio Institute of Cardiovascular Imaging. Dr. Min is an attending physician at NewYork-Presbyterian Hospital and a full-time faculty member in the Department of Radiology at Weill Cornell Medical College. He joins NewYork-Presbyterian/Weill Cornell from the Cedars-Sinai Medical Center, where he was director of cardiac imaging research and co-director of cardiac imaging. Rooted in the central role of imaging techniques to better diagnose cardiovascular disease, the institute will not only use state-of-the-art tools such as MRI, CT, and PET scanners, but will also focus on the development of novel next-generation technologies and diagnostic tests.Applying a team-based approach that draws on the expertise of physicians and scientists in radiology, cardiology, genetics, proteomics, and computational biology, the institute’s primary research initiative is to identify the “vulnerable plaque,” or the specific coronary artery lesion that is responsible for a future heart attack or sudden cardiac death.“The vulnerable plaque is the holy grail in the diagnostic work-up of individuals with suspected coronary artery disease, and its elusive nature has precluded the timely treatment of millions of high-risk individuals,” says Dr. Min. “We will apply an array of innovative hardware and software imaging technologies to improve identification of the vulnerable plaque, and then seek to apply these findings in large-scale multicenter clinical trials and registries to encourage full integration of our research findings into clinical practice.”
To develop the world-class clinical program to diagnose early cardiovascular disease, the Dalio Institute of Cardiovascular Imaging will use state-of-the-art imaging technologies in conjunction with other cutting-edge diagnostic tests, including blood markers of inflammation, protein expression, and metabolism. The clinical program will serve patients in the outpatient and inpatient setting, as well as in the emergency department. Three specific initiatives within the clinical program will emphasize
early identification of heart disease in women,
ethnic minorities, and
young patients with a family history of premature heart disease.
The institute’s educational mission will focus on disseminating knowledge of the latest advances in cardiovascular imaging through the education of physicians, physician trainees, and allied health professionals through formal didactic curricula and symposia.
“More than half of people who die from sudden heart attacks never knew they were at risk because their underlying heart conditions had never been diagnosed,” says Dr. Min. “Many heart attacks can be prevented if people know of the extent and severity of their asymptomatic heart disease and are properly treated. By bringing together a multidisciplinary group of experts, the Dalio Institute of Cardiovascular Imaging will not just offer the latest imaging techniques for early detection, but will also develop disruptive technologies to fight the battle against heart disease. Ultimately, these pioneering methods aim to challenge current clinical paradigms in order to reduce the morbidity and mortality associated with cardiovascular disease.”
“Establishing the Dalio Institute of Cardiovascular Imaging is an incredibly significant milestone in our fight against heart disease,” says Dr. Steven J. Corwin, CEO of NewYork-Presbyterian Hospital and a cardiologist by training. “While modern medicine offers highly sophisticated tools for treating heart disease, we still have a long way to go in terms of identifying high-risk individuals with early-stage disease so that we can prevent catastrophic outcomes and save lives. Dr. Min’s unique background, expertise, and clinical research experience make him ideally suited to lead the institute and its groundbreaking initiatives. We are thrilled that Dr. Min has joined us, and we are extraordinarily grateful to Ray Dalio for his vision and generous support.”
“The interdisciplinary nature of the new Dalio Institute of Cardiovascular Imaging exemplifies the best in translational research – investigations that can make lifesaving impact on our patients,” says Dr. Laurie H. Glimcher, the Stephen and Suzanne Weiss Dean of Weill Cornell Medical College. “Dr. Min has a proven track record of effectively testing novel theories, and we enthusiastically support what we know will be innovative research at the institute.”
NewYork-Presbyterian/Weill Cornell Medical Center, located in New York City, is one of the leading academic medical centers in the world, comprising the teaching hospital NewYork-Presbyterian and Weill Cornell Medical College, the medical school of Cornell University. NewYork-Presbyterian/Weill Cornell provides state-of-the-art inpatient, ambulatory and preventive care in all areas of medicine, and is committed to excellence in patient care, education, research and community service. Weill Cornell physician-scientists have been responsible for many medical advances – including the development of the Pap test for cervical cancer; the synthesis of penicillin; the first successful embryo-biopsy pregnancy and birth in the U.S.; the first clinical trial for gene therapy for Parkinson’s disease; the first indication of bone marrow’s critical role in tumor growth; and, most recently, the world’s first successful use of deep brain stimulation to treat a minimally conscious brain-injured patient. NewYork-Presbyterian Hospital also comprises NewYork-Presbyterian/Columbia University Medical Center, NewYork-Presbyterian/Morgan Stanley Children’s Hospital, NewYork-Presbyterian/Westchester Division, NewYork-Presbyterian/The Allen Hospital, and NewYork-Presbyterian/Lower Manhattan Hospital. NewYork-Presbyterian is the #1 hospital in the New York metropolitan area and is consistently ranked among the best academic medical institutions in the nation, according to U.S.News & World Report. Weill Cornell Medical College is the first U.S. medical college to offer a medical degree overseas and maintains a strong global presence in Austria, Brazil, Haiti, Tanzania, Turkey and Qatar. For more information, visit http://www.nyp.org and weill.cornell.edu.
Part IV: 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
Part VI: Calcium Cycling (ATPase Pump) in Cardiac Gene Therapy: Inhalable Gene Therapy for Pulmonary Arterial Hypertension and Percutaneous Intra-coronary Artery Infusion for Heart Failure: Contributions by Roger J. Hajjar, MD
Part VIII: 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
Part XII: Atherosclerosis Independence: Genetic Polymorphisms of Ion Channels Role in the Pathogenesis of Coronary Microvascular Dysfunction and Myocardial Ischemia (Coronary Artery Disease (CAD))
Larry H Bernstein, MD, FCAP and Aviva Lev-Ari, PhD, RN
This article, constitute, Part II, it is a broad, but not complete review of the emerging discoveries of the critical role of calcium signaling on cell motility and by extension, embryonic development, cancer metastasis, changes in vascular compliance at the junction between the endothelium and the underlying interstitial layer. The effect of calcium signaling on the heart in arrhtmogenesis and heart failure will be a third in this series, while the binding of calcium to troponin C in the synchronous contraction of the myocardium had been discussed by Dr. Lev-Ari in Part I.
Universal MOTIFs essential to skeletal muscle, smooth muscle, cardiac syncytial muscle, endothelium, neovascularization, atherosclerosis and hypertension, cell division, embryogenesis, and cancer metastasis. The discussion will be presented in several parts:
1. Biochemical and signaling cascades in cell motility
2. Extracellular matrix and cell-ECM adhesions
3. Actin dynamics in cell-cell adhesion
4. Effect of intracellular Ca++ action on cell motility
5. Regulation of the cytoskeleton
6. Role of thymosin in actin-sequestration
7. T-lymphocyte signaling and the actin cytoskeleton
Part 1. Biochemical and Signaling Cascades in Cell Motility
Cell motility or migration is an essential cellular process for a variety of biological events. In embryonic development, cells migrate to appropriate locations for the morphogenesis of tissues and organs. Cells need to migrate to heal the wound in repairing damaged tissue. Vascular endothelial cells (ECs) migrate to form new capillaries during angiogenesis. White blood cells migrate to the sites of inflammation to kill bacteria. Cancer cell metastasis involves their migration through the blood vessel wall to invade surrounding tissues.
Variety of important roles for cell migration:
1. Embryogenesis
2. Wound healing (secondary extension)
3. Inflammatory infiltrate (chemotaxis)
4. Angiogenesis
5. Cancer metastasis
6. Arterial compliance
7. Myocardial and skeletal muscle contraction
8. Cell division
Portrait of Cell in Migration:
1. protrusion of leading edge
2. Formation of new adhesions at front
3. Cell contraction
4. Release of adhesions at rear
Microenvironmental factor:
1. Concentration gradient of chemoattractants
2. Gradient of immobilized ECM proteins
3. Gradient of matrix rigidity
4. Mechanotaxis
Extracellular signals are sensed by receptors or mechanosensors on cell surface or in cell interior to initiate migration. Actin polymerization is the key event leading to protrusion at the leading edge and new focal adhesions anchor the actin filaments and the cell to the underlying surface. This is followed by contraction of the actin filaments. The contraction of actomyosin filaments pulls the elongate body forward and at the same time the tail retracts.
Part 2. Cell-ECM Adhesions
Cytoskeleton and cell-ECM adhesions are two major molecular machineries involved in mechano-chemical signal transduction during cell migration. Although all three types of cytoskeleton (actin microfilaments, microtubules, and intermediate filaments) contribute to cell motility, actin cytoskeleton plays the central role. The polymerization of actin filaments provides the driving force for the protrusion of the leading edge as lamellipodia (sheet-like protrusions) or filopodia (spike-like protrusions), and actomyosin contraction generates the traction force at (focal adhesions) FAs and induces the retraction at the rear. It is generally accepted that actin filaments interact with the double-headed myosin to generate the force for cell motility and that actomyosin contraction/relaxation involves the modulation of myosin light chain (MLC) phosphorylation. Rho family GTPases, including Cdc42, Rac, and Rho, are the key regulators of actin polymerization, actomyosin contraction, and cell motility. Cdc42 activation induces the formation of filopodia; Rac activation induces lamellipodia; and Rho activation increases actin polymerization, stress fiber formation, and actomyosin contractility. All three types of Rho GTPases stimulate new FA formation.
Integrins are the major receptors for ECM proteins. The integrin family includes more than 20 transmembrane heterodimers composed of α and β subunits with noncovalent association. The extracellular domain of integrin binds to specific ligands, e.g., ECM proteins such as fibronectin (FN), vitronectin, collagen, and laminin. The cytoplasmic domain interacts with cytoskeletal proteins (e.g., paxillin, talin, vinculin, and actin) and signaling molecules in the focal adhesion (FA) sites. The unique structural features of integrins enable them to mediate outside-in signaling, in which extracellular stimuli induce the intracellular signaling cascade via integrin activation, and inside-out signaling, in which intracellular signals modulate integrin activation and force generation through FAs.
Part 3. Actin Dynamics in Cell-cell Adhesion
Actin filaments are linked to the focal adhesions (Fas) between cell and ECM through a protein complex that includes talin, vinculin, α-actinin, and filamin. Such a complex couples the actomyosin contractile apparatus to FAs, and plays an important role in the force transmission between ECM and the cell.
3a. Actin dynamics and cell–cell adhesion in epithelia
Valeri Vasioukhin and Elaine Fuchs
Howard Hughes Medical Institute, Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, IL
Current Opinion in Cell Biology 2001, 13:76–84
Recent advances in the field of intercellular adhesion highlight the importance of adherens junction association with the underlying actin cytoskeleton. In skin epithelial cells a dynamic feature of adherens junction formation involves filopodia, which physically project into the membrane of adjacent cells, catalyzing the clustering of adherens junction protein complexes at their tips. In turn, actin polymerization is stimulated at the cytoplasmic interface of these complexes. Although the mechanism remains unclear, the VASP/Mena family of proteins seems to be involved in organizing actin polymerization at these sites. In vivo, adherens junction formation appears to rely upon filopodia in processes where epithelial sheets must be physically moved closer to form stable intercellular connections, for example, in ventral closure in embryonic development or wound healing in the postnatal animal.
Located at cell–cell borders, adherens junctions are electron dense transmembrane structures that associate with the actin cytoskeleton. In their absence, the formation of other cell–cell adhesion structures is dramatically reduced. The transmembrane core of adherens junctions consists of cadherins, of which E-cadherin is the epithelial prototype. Its extracellular domain is responsible for homotypic, calcium-dependent, adhesive interactions with E-cadherins on the surface of opposing cells. Its cytoplasmic domain is important for associations with other intracellular proteins involved in the clustering of surface cadherins to form a junctional structure.
The extracellular domain of the transmembrane E-cadherin dimerizes and interacts in a calcium-dependent manner with similar molecules on neighboring cells. The intracellular juxtamembrane part of E-cadherin binds to p120ctn, an armadillo repeat protein capable of modulating E-cadherin clustering. The distal segment of E-cadherin’s cytoplasmic domain can interact with β-catenin or plakoglobin, armadillo repeat proteins which in turn bind to α-catenin. The carboxyl end of α-catenin binds directly to f-actin, and, through a direct mechanism, α-catenin can link the membrane-bound cadherin–catenin complex to the actin cytoskeleton. Additionally, α-catenin can bind to either vinculin or ZO1, and it is required for junctional localization of zyxin. Vinculin and zyxin can recruit VASP (and related family members), which in turn can associate with the actin cytoskeleton, providing the indirect mechanism to link the actin cytoskeleton to adherens junctions. ZO1 is also a member of tight junctions family, providing a means to link these junctions with adherens junctions.
Through a site near its transmembrane domain, cadherins bind directly to the catenin p120ctn, and through a more central site within the cytoplasmic domain, cadherins bind preferentially to β-catenin. Cell migration appears to be promoted by p120ctn through recruiting and activating small GTPases. β-catenin is normally involved in adherens junction formation through its ability to bind to β-catenin and link cadherins to the actin cytoskeleton. However, β-catenin leads a dual life in that it can also act as a transcriptional cofactor when stimulated by the Wnt signal transduction pathway
α-Catenin: More than just a Bridge between Adherens Junctions and the Actin Cytoskeleton
α-catenin was initially discovered as a member of the E-cadherin–catenin complex. It is related to vinculin, an actin-binding protein that is found at integrin-based focal contacts. The amino-terminal domain of α-catenin is involved in α-catenin/plakoglobin binding and is also important for dimerization. Its central segment can bind to α-actinin and to vinculin, and it partially encompasses the region of the protein necessary for cell adhesion (which is the adhesion-modulation domain; amino acids 509–643). The carboxy-terminal domain of both vinculin and α-catenin is involved in filamentous actin (f-actin) binding, and for α-catenin, this domain is also involved in binding to ZO1. VH1, VH2 and VH3 are three regions sharing homology to vinculin. The percentage amino acid identity and the numbers correspond to the amino acid residues of the α-catenin polypeptide.
α-catenin is the only catenin that can directly bind to actin filaments , and E-cadherin–catenin complexes do not associate with the actin cytoskeleton after α-catenin is removed by extraction with detergent. Cancer cell lines lacking α-catenin still express E-cadherin and β-catenin, but do not show proper cell–cell adhesion unless the wild-type gene is reintroduced into the cancer cell. This provides strong evidence that clustering of the E-cadherin–catenin complex and cell–cell adhesion requires the presence of α-catenin.
Although intercellular adhesion is dependent upon association of the E-cadherin–β-catenin protein complex with α-catenin and the actin cytoskeleton, it is unclear whether α-catenin’s role goes beyond linking the two structures. Fusion of a nonfunctional tailless E-cadherin (E C71) with α-catenin resulted in a chimeric protein able to confer cell–cell adhesion on mouse fibroblasts in vitro, and generation of additional chimeric proteins enabled delineation of the region of α-catenin that is important for cell aggregation. Not surprisingly, the essential domain of α-catenin was its carboxy-terminal domain (~amino acids 510–906), containing the actin-binding site, which encompasses residues 630–906 of this domain.
The binding of α-catenin to the actin cytoskeleton is required for cell–cell adhesion, but α-catenin appears to have additional function(s) beyond its ability to link E-cadherin–β-catenin complexes to actin filaments. The domain encompassing residues 509–643 of α-catenin has been referred to as an adhesion-modulation domain to reflect this added, and as yet unidentified, function. Besides its association with β-catenin and f-actin, α-catenin binds to a number of additional proteins, some of which are actin binding proteins themselves. Additionally, the localization of vinculin to cell–cell borders is dependent upon the presence of α-catenin. α-catenin can also bind to the MAGUK (membrane-associated guanylate kinase) family members ZO1 and ZO2. Thus, the role for α-catenin might not simply be to link E-cadherin–catenin complexes to the actin cytoskeleton but rather to organize a multiprotein complex with multiple actin-binding, bundling and polymerization activities.
The decisive requirement for α-catenin’s actin-binding domain in adherens junction formation underscores the importance of the actin cytoskeleton in intercellular adhesion. Thus, it is perhaps not surprising that the majority of f-actin in epithelial cells localizes to cell–cell junctions. When epidermal cells are incubated in vitro in culture media with calcium concentrations below 0.08 mM they are unable to form adherens junctions. However, when the calcium concentrations are raised to the levels naturally occurring in skin (1.5–1.8 mM), intercellular adhesion is initiated.
This switch in part promotes a calcium-dependent conformational change in the extracellular domain of E-cadherin that is necessary for homotypic interactions to take place. It appears that the actin cytoskeleton has a role in facilitating the process that brings opposing membranes together and stabilizing them once junction formation has been initiated. In this regard, the formation of cell–cell adhesion can be divided into two categories:
active adhesion, a process that utilizes the actin cytoskeleton to generate the force necessary to bring opposing membranes together, and
passive adhesion, a process which may not require actin if the membranes are already closely juxtaposed and stabilized by the deposition of cadherin–catenin complexes.
Upon a switch from low to high calcium, cadherin-mediated intercellular adhesion is activated. Passive adhesion: in cells whose actin cytoskeleton has been largely disrupted by cytochalasin D, cadherin–catenin complexes occur at sites where membranes of neighboring cells directly contact each other. Active adhesion: neighboring cells with functional actin cytoskeletons can draw their membranes together, forming a continuous epithelial sheet. Upon initial membrane contact, E-cadherin forms punctate aggregates or puncta along regions where opposing membranes are in contact with one another. Each of these puncta is contacted by a bundle of actin filaments that branch off from the cortical belt of actin filaments underlying the cell membrane. At later stages in the process, those segments of the circumferential actin cables that reside along the zone of cell–cell contacts disappear, and the resulting semi-circles of cortical actin align to form a seemingly single circumferential cable around the perimeter of the two cells. At the edges of the zone of cell–cell contact, plaques of E-cadherin–catenin complexes connect the cortical belt of actin to the line of adhesion. At the center of the developing zone of adhesion, E-cadherin puncta associate with small bundles of actin filaments oriented perpendicular to the zone.
Multiple E-cadherin-containing puncta that form along the developing contact rapidly associate with small bundles of actin filaments. As the contact between cells lengthens, puncta continue to develop at a constant average density, with new puncta at the edges of the contact. The segment of the circumferential actin cable that underlies the developing contact gradually ‘dissolves’, and merges into a large cable, encompassing both cells. This is made possible through cable-mediated connections to the E-cadherin plaques at the edges of the contact. As contact propagates, E-cadherin is deposited along the junction as a continuous line. The actin cytoskeleton reorganizes and is now oriented along the cell–cell contact. In primary keratinocytes, two neighboring cells send out filopodia, which, upon contact, slide along each other and project into the opposing cell’s membrane. Filopodia are rich in f-actin. Embedded tips of filopodia are stabilized by puncta, which are transmembrane clusters of adherens junction proteins.
This process draws regions of the two cell surfaces together, which are then clamped by desmosomes. Radial actin fibers reorganize at filopodia tips in a zyxin-, vinculin-, VASP-, and Mena-dependent fashion. Actin polymerization is initiated at stabilized puncta, creating the directed reverse force needed to push and merge puncta into a single line as new puncta form at the edges. The actin-based movement physically brings remaining regions of opposing membranes together and seals them into epithelial sheets. As filopodia contain actin rather than keratin intermediate filaments, they become natural zones of adherens junctions, whereas the cell surface flanking filopodia becomes fertile ground for desmosome formation, alternating adherens junctions and desmosomes.
Possible Roles of Myosin in Cell–cell Adhesion.
[a] A hypothetical ‘purse string’ model for myosin-driven epithelial sheet closure at a large circular wound site in the cornea of an adult mouse. At the edge of wound site epithelial cables of actin appear to extend from cell to cell, forming a ring around the wound circumference. Contraction of actin cables driven by myosin can lead to wound closure.
[b] Inside out ‘purse string’ model for contact propagation (compaction) in MDCK cells. During contact formation in MDCK cells, circumferential actin cables contact cadherin–catenin plaques at the edges of the contact. Contraction of actin cables driven by myosin can lead to the contact expansion.
What Regulates the Actin Dynamics that are Important for Cell–cell Adhesion?
The answer to this remains uncertain, but the small GTPases of the Rho family seem to be likely candidates, given that Rho, Rac1 and Cdc42 promote stress fiber, lamellipodia and filopodia formation, respectively.
In vivo mutagenesis studies in Drosophila reveal a role for Rac1 and Rho in dorsal closure and/or in head involution, processes that involve complex and well orchestrated rearrangements of cells. In contrast, Cdc42 appears to be involved in regulating polarized cell shape changes. In vitro, keratinocytes microinjected with dominant negative Rac1 or with C3 toxin, a specific inhibitor of Rho, are unable to form cadherin-based cell–cell contacts. Similarly, overexpression of a constitutively active form of Rac1 or Cdc42 in MDCK cells increases junctional localization of E-cadherin–catenin complexes, whereas the dominant negative forms of Rac1 and Cdc42, or C3 microinjection, have the opposite effect. The finding that Tiam1, a guanine nucleotide exchange factor for Rac1, increases E-cadherin mediated cell–cell adhesion, inhibits hepatocyte growth-factor-induced cell scattering and reverses the loss of adhesion in Ras-transformed cells is consistent with the above. Together, these findings provide compelling evidence that activation of the Rho family of small GTPases plays a key role in the actin dynamics that are necessary for adherens junction formation.
We found that E-cadherin–catenin-enriched puncta, which assemble during the first stages of epithelial sheet formation, are sites of de novo actin polymerization. This led us to postulate that actin polymerization might provide the force that is subsequently necessary to merge the double role of puncta into a single row and ultimately into an epithelial sheet. Knowledge of how actin polymerization might generate movement comes largely from studies of the mechanism by which the pathogen Listeria monocytogenes pirates actin polymerization and utilizes it for intracellular propulsion. For this endeavor, these bacteria recruit two types of cellular components, the VASP family of proteins and the Arp2/3 complex. The Arp2/3 protein complex is required for de novo nucleation of actin filament polymerization, whereas VASP appears to accelerate bacterial movement by about 10 fold.
Although most studies have revealed positive roles for VASP and its cousins in actin reorganization/ polymerization, recent experiments have shown that in certain instances these proteins act negatively in directing cell movement. A further complication is the finding that VASP family proteins can be phosphorylated, thereby inhibiting their actin nucleation and f-actin binding ability. A role for VASP may be in the actin polymerization necessary for filopodia extensions. In this regard, VASP family proteins localize to the tips of filopodia during neural growth and in calcium-stimulated keratinocytes. VASP family proteins in this process might provide directionality to the process of actin polymerization, reshaping f-actin into parallel bundles to produce and extend filopodia-like structures from branched lamellipodial networks.
The Might of Myosins
Although actin polymerization seems to be important in generating the cellular movement necessary for intercellular adhesion, this does not rule out the possibility that the myosin family of actin motor proteins may also play a role. It is known, for instance, that cells can use myosin–actin contractile forces to alter cell shape, and myosin II is a ubiquitously expressed protein involved in such diverse processes as cell spreading, cytokinesis, cell migration, generation of tension within actin stress fiber networks and retrograde flow of actin filaments at the leading edge of moving cells. Interestingly, mouse corneal cells at a wound edge assemble cables of actin filaments anchored to E-cadherin–catenin complexes. The cells surrounding the wound site display myosin-II-associated actin filaments that are aligned in a structure resembling a purse string. It has been postulated that closure of the wound may be achieved through myosin-directed contraction of the actin filaments, in a mechanism similar to that of pulling on a purse string.
Overall, through guilt by association, myosins have been implicated in cell–cell adhesion and in adherens junction formation and although the models proposed are attractive, direct experimental evidence is still lacking. BDM (2,3-butanedione monoxime), a general inhibitor of myosin function, had no obvious effect on intercellular junction formation in our keratinocyte adhesion assays (V Vasioukhin, E Fuchs, unpublished data). However, the role of myosins clearly deserves a more detailed investigation, and this awaits the development of new and improved inhibitors and activators of myosin action.
Key references:
1. Imamura Y, Itoh M, Maeno Y, Tsukita S, Nagafuchi A: Functional domains of α-catenin required for the strong state of cadherin based cell adhesion. J Cell Biol 1999, 144:1311-1322.
Three distinct functional domains for α-catenin were identified: a vinculin binding domain, a ZO-1-binding domain and an adhesion modulation domain. Both ZO1-binding (also actin binding) and adhesion modulation domains are necessary for strong adhesion.
2. Vasioukhin V, Bauer C, Yin M, Fuchs E: Directed actin polymerization is the driving force for epithelial cell–cell adhesion. Cell 2000, 100:209-219.
A dynamic filopodia-driven process of cell–cell adhesion is described in primary mouse keratinocyte cultures. Newly forming adherens junctions were identified as sites of actin polymerization and/or reorganization, involving VASP/Mena family members.
An elegant in vivo analysis of filopodia-based cell–cell junction formation during epithelial-sheet closure in embryonic development of C. elegans.
4. Loisel TP, Boujemaa R, Pantaloni D, Carlier MF: Reconstitution of actin-based motility of Listeria and Shigella using pure proteins. Nature 1999, 401:613-616.
Using an in vitro reconstitution approach, the authors show that Arp2/3, actin, cofilin and capping proteins are required for motility of Listeria, in contrast VASP seems to act by increasing the speed of movement by about 10 fold.
3b. Role for Gelsolin in Actuating Epidermal Growth Factor Receptor-mediated Cell Motility
Philip Chen, Joanne E. Murphy-Ullrich, and Alan Wells
Department of Pathology, University of Alabama at Birmingham, AL
J Cell Biology Aug 1996; 134(3): 689-698
Phospholipase C-~/(PLC~/) is required for EGF-induced motility (Chen, P., H. Xie, M.C. Sekar, K.B. Gupta, and A. Wells. J. Cell Biol. 1994. 127:847-857); however, the molecular basis of how PLC~/modulates the actin filament network underlying cell motility remains undetermined. One connection to the actin cytoskeleton may be direct hydrolysis of PIP 2 with subsequent mobilization of membrane-associated actin modifying proteins. We used signaling restricted EGFR mutants expressed in receptor-devoid NR6 fibroblast cells to investigate whether EGFR activation of PLC causes gelsolin mobilization from the cell membrane in vivo and whether this translocation facilitates cell movement. Gelsolin anti-sense oligonucleotide (20 p,M) treatment of NR6 ceils expressing the motogenic full-length (WT) and truncated c’ 1000 EGFR decreased endogenous gelsolin by 30–60%; this resulted in preferential reduction of EGF (25 nM)-induced cell movement by >50% with little effect on the basal motility. As 14 h of EGF stimulation of cells did not increase total cell gelsolin content, we determined whether EGF induced redistribution of gelsolin from the membrane fraction. EGF treatment decreased the gelsolin mass associated with the membrane fraction in motogenic WT and c’1000 EGFR NR6 cells but not in cells expressing the fully mitogenic, but nonmotogenic c’973 EGFR. Blocking PLC activity with the pharmacologic agent U73122 (1 ~M) diminished both this mobilization of gelsolin and EGF-induced motility, suggesting that gelsolin mobilization is downstream of PLC. Concomitantly observed was reorganization of submembranous actin filaments correlating directly with PLC activation and gelsolin mobilization. In vivo expression of a peptide that is reported to compete in vitro with gelsolin in binding to PIP2 dramatically increased basal cell motility in NR6 cells expressing either motogenic (WT and c’1000) or nonmotogenic (c’973) EGFR; EGF did not further augment cell motility and gelsolin mobilization. Cells expressing this peptide demonstrated actin reorganization similar to that observed in EGF-treated control cells; the peptide-induced changes were unaffected by U73122. These data suggest that much of the EGF induced motility and cytoskeletal alterations can be reproduced by displacement of select actin-modifying proteins from a PIP2-bound state. This provides a signaling mechanism for translating cell surface receptor mediated biochemical reactions to the cell movement machinery.
3c. Actomyosin Contraction at the Cell Rear Drives Nuclear Translocation in Migrating Cortical Interneurons
Francisco J. Martini and Miguel Valdeolmillos
Instituto de Neurociencias de Alicante, Universidad Miguel Hernandez, Alacant, Spain
Journal of Neuroscience 2010 • 30(25):8660–8670
Neuronal migration is a complex process requiring the coordinated interaction of cytoskeletal components and regulated by calcium signaling among other factors. Migratory neurons are polarized cells in which the largest intracellular organelle, the nucleus, has to move repeatedly. Current views support a central role for pulling forces that drive nuclear movement. By analyzing interneurons migrating in cortical slices of mouse brains, we have found that nucleokinesis is associated with a precise pattern of actin dynamics characterized by the initial formation of a cup-like actin structure at the rear nuclear pole. Time-lapse experiments show that progressive actomyosin contraction drives the nucleus forward. Nucleokinesis concludes with the complete contraction of the cup-like structure, resulting in an actin spot at the base of the retracting trailing process. Our results demonstrate that this actin remodeling requires a threshold calcium level provided by low-frequency spontaneous fast intracellular calcium transients. Microtubule stabilization with taxol treatment prevents actin remodeling and nucleokinesis, whereas cells with a collapsed microtubule cytoskeleton induced by nocodazole treatment, display nearly normal actin dynamics and nucleokinesis. In summary, the results presented here demonstrate that actomyosin forces acting at the rear side of the nucleus drives nucleokinesis in tangentially migrating interneurons in a process that requires calcium and a dynamic cytoskeleton of microtubules.
3d. Migration of Zebrafish Primordial Germ Cells: A Role for Myosin Contraction and Cytoplasmic Flow
H Blaser, M Reichman-Fried, I Castanon, K Dumstrei, F L Marlow, et al.
Max Planck Institute, Gottingen & Dresden, Germany; Vanderbilt University, Nashville, Tenn; National Institute of Genetics, Shizuoka, Japan
The molecular and cellular mechanisms governing cell motility and directed migration in response to the chemokine SDF-1 are largely unknown. Here, we demonstrate that zebrafish primordial germ cells whose migration is guided by SDF-1 generate bleb-like protrusions that are powered by cytoplasmic flow. Protrusions are formed at sites of higher levels of free calcium where activation of myosin contraction occurs. Separation of the acto-myosin cortex from the plasma membrane at these sites is followed by a flow of cytoplasm into the forming bleb. We propose that polarized activation of the receptor CXCR4 leads to a rise in free calcium that in turn activates myosin contraction in the part of the cell responding to higher levels of the ligand SDF-1. The biased formation of new protrusions in a particular region of the cell in response to SDF-1 defines the leading edge and the direction of cell migration.
Part 4. Calcium Signaling
4a. Indirect Association of Ezrin with F-Actin: Isoform Specificity and Calcium Sensitivity
Charles B. Shuster and Ira M. Herman
Tufts University Health Science Schools, Boston, MA
J Cell Biology Mar 1995; 128(5): 837-848
Muscle and nonmuscle isoactins are segregated into distinct cytoplasmic domains, but the mechanism regulating subcellular sorting is unknown (Herman, 1993a). To reveal whether isoform-specific actin-binding proteins function to coordinate these events, cell extracts derived from motile (Era) versus stationary (Es) cytoplasm were selectively and sequentially fractionated over filamentous isoactin affinity columns prior to elution with a KC1 step gradient. A polypeptide of interest, which binds specifically to/3-actin filament columns, but not to muscle actin columns has been conclusively identified as the ERM family member, ezrin. We studied ezrin-/3 interactions in vitro by passing extracts (Era) over isoactin affinity matrices in the presence of Ca2+-containing versus Ca2+-free buffers, with or without cytochalasin D. Ezrin binds and can be released from/3-actin Sepharose-4B in the presence of Mg2+/EGTA and 100 mM NaC1 (at 4°C and room temperature), but not when affinity fractionation of Em is carried out in the presence of 0.2 mM CaC12 or 2/~M cytochalasin D. N-acetyl-(leucyl)2-norleucinal and E64, two specific inhibitors of the calcium-activated protease, calpain I, protect ezrin binding to β-actin in the presence of calcium. Biochemical analysis of endothelial lysates reveals that a calpain I cleavage product of ezrin emerges when cell locomotion is stimulated in response to monolayer injury. Immunofluorescence analysis shows that anti-ezrin and anti-β-actin IgGs can be simultaneously co-localized, extending the results of isoactin affinity fractionation of Em-derived extracts and suggesting that ezrin and β-actin interact in vivo. To test the hypothesis that ezrin binds directly to β-actin, we performed three sets of studies under a wide range of physiological conditions (pH 7.0-8.5) using purified pericyte ezrin and either α- or β-actin. Results of these experiments reveal that purified ezrin does not directly bind to β-actin filaments. We mapped cellular free calcium in endothelial monolayers crawling in response to injury. Confocal imaging of fluo-3 fluorescence followed by simultaneous double antibody staining reveals a transient rise of free calcium within ezrin-/3-actin-enriched domains in the majority of motile cells bordering the wound edge. These results support the notion that calcium and calpain I modulate ezrin and β-actin interactions during forward protrusion formation.
4b. Calcium channel and glutamate receptor activities regulate actin organization in salamander retinal neurons
Massimiliano Cristofanilli and Abram Akopian
New York University School of Medicine, New York, NY
J Physiol 575.2 (2006) pp 543–554
Intracellular Ca2+ regulates a variety of neuronal functions, including neurotransmitter release, protein phosphorylation, gene expression and synaptic plasticity. In a variety of cell types, including neurons, Ca2+ is involved in actin reorganization, resulting in either actin polymerization or depolymerization. Very little, however, is known about the relationship between Ca2+ and the actin cytoskeleton organization in retinal neurons. We studied the effect of high-K+-induced depolarization on F-actin organization in salamander retina and found that Ca2+ influx through voltage-gated L-type channels causes F-actin disruption, as assessed by 53±5% (n=23, P <0.001) reduction in the intensity of staining with Alexa-Fluor488-phalloidin, a compound that permits visualization and quantification of polymerized actin. Calcium-induced F-actin depolymerization was attenuated in the presence of protein kinase C antagonists, chelerythrine or bis-indolylmaleimide hydrochloride (GF 109203X). In addition, phorbol 12-myristate 13-acetate (PMA), but not 4α-PMA, mimicked the effect of Ca2+ influx on F-actin. Activation of ionotropic AMPA and NMDA glutamate receptors also caused a reduction in F-actin. No effect on F-actin was exerted by caffeine or thapsigargin, agents that stimulate Ca2+ release from internal stores. In whole-cell recording from a slice preparation, light-evoked ‘off’ but not ‘on’ EPSCs in ‘on–off’ ganglion cells were reduced by 60±8% (n=8, P <0.01) by cytochalasin D. These data suggest that elevation of intracellular Ca2+ during excitatory synaptic activity initiates a cascade for activity-dependent actin remodelling, which in turn may serve as a feedback mechanism to attenuate excite-toxic Ca2+ accumulation induced by synaptic depolarization.
4c. Electric Field-directed Cell Shape Changes, Displacement, and Cytoskeletal Reorganization Are Calcium Dependent
Edward K. Onuma and Sek-Wen Hui
Roswell Park Memorial Institute, Buffalo, New York
J Cell Biology 1988; 106: 2067-2075
C3H/10T1/2 mouse embryo fibroblasts were stimulated by a steady electric field ranging up to 10 V/cm. Some cells elongated and aligned perpendicular to the field direction. A preferential positional shift toward the cathode was observed which was inhibited by the calcium channel blocker D-600 and the calmodulin antagonist trifluoperazine. Rhodaminephalloidin labeling of actin filaments revealed a field induced disorganization of the stress fiber pattern, which was reduced when stimulation was conducted in calcium-depleted buffer or in buffer containing calcium antagonist CoC12, calcium channel blocker D-600, or calmodulin antagonist trifluoperazine. Treatment with calcium ionophore A23187 had similar effects, except that the presence of D-600 did not reduce the stress fiber disruption. The calcium-sensitive photoprotein aequorin was used to monitor changes in intracellular-free calcium. Electric stimulation caused an increase of calcium to the micromolar range. This increase was inhibited by calcium-depleted buffer or by CoC12, and was reduced by D-600. A calcium-dependent mechanism is proposed to explain the observed field-directed cell shape changes, preferential orientation, and displacement.
4d. Local Calcium Elevation and Cell Elongation Initiate Guided Motility in Electrically Stimulated osteoblast-Like Cells
N Ozkucur, TK Monsees, S Perike, H Quynh Do, RHW Funk.
Carl Gustav Carus, TU-Dresden, Dresden, Germany; University of the Western Cape, SAfrica.
Plos ONE 2009; 4 (7): e6131
Investigation of the mechanisms of guided cell migration can contribute to our understanding of many crucial biological processes, such as development and regeneration. Endogenous and exogenous direct current electric fields (dcEF) are known to induce directional cell migration, however the initial cellular responses to electrical stimulation are poorly understood. Ion fluxes, besides regulating intracellular homeostasis, have been implicated in many biological events, including regeneration. Therefore understanding intracellular ion kinetics during EF-directed cell migration can provide useful information for development and regeneration.
We analyzed the initial events during migration of two osteogenic cell types, rat calvarial and human SaOS-2 cells, exposed to strong (10–15 V/cm) and weak (#5 V/cm) dcEFs. Cell elongation and perpendicular orientation to the EF vector occurred in a time- and voltage-dependent manner. Calvarial osteoblasts migrated to the cathode as they formed new filopodia or lamellipodia and reorganized their cytoskeleton on the cathodal side. SaOS-2 cells showed similar responses except towards the anode. Strong dcEFs triggered a rapid increase in intracellular calcium levels, whereas a steady state level of intracellular calcium was observed in weaker fields. Interestingly, we found that dcEF induced intracellular calcium elevation was initiated with a local rise on opposite sides in calvarial and SaOS-2 cells, which may explain their preferred directionality. In calcium-free conditions, dcEFs induced neither intracellular calcium elevation nor directed migration, indicating an important role for calcium ions. Blocking studies using cadmium chloride revealed that voltage-gated calcium channels (VGCCs) are involved in dcEF-induced intracellular calcium elevation. Taken together, these data form a time scale of the morphological and physiological rearrangements underlying EF-guided migration of osteoblast-like cell types and reveal a requirement for calcium in these reactions. We show for the first time here that dcEFs trigger different patterns of intracellular calcium elevation and positional shifting in osteogenic cell types that migrate in opposite directions.
4e. TRPM4 Regulates Migration of Mast Cells in Mice
T Shimizua, G Owsianik, M Freichelb, V Flockerzi, et al.
Laboratory of Ion Channel Research, KU Leuven, Leuven, Belgium; Universität des Saarlandes, Homburg, Germany; National Institute for Physiological Sciences,Okazaki, Japan
Cell Calcium 2008; xxx–xxx
We demonstrate here that the transient receptor potential melastatin subfamily channel, TRPM4, controls migration of bone marrow-derived mast cells (BMMCs), triggered by dinitrophenylated human serum albumin (DNP-HSA) or stem cell factor (SCF). Wild-type BMMCs migrate after stimulation with DNPHSA or SCF whereas both stimuli do not induce migration in BMMCs derived from TRPM4 knockout mice (trpm4−/−). Mast cell migration is a Ca2+-dependent process, and TRPM4 likely controls this process by setting the intracellular Ca2+ level upon cell stimulation. Cell migration depends on filamentous actin (F-actin) rearrangement, since pretreatment with cytochalasin B, an inhibitor of F-actin formation, prevented both DNP-HSA- and SCF-induced migration in wild-type BMMC. Immunocytochemical experiments using fluorescence-conjugated phalloidin demonstrate a reduced level of F-actin formation in DNP-HSA-stimulated BMMCs from trpm4−/− mice. Thus, our results suggest that TRPM4 is critically involved in migration of BMMCs by regulation of Ca2+-dependent actin cytoskeleton rearrangements.
4f. Nuclear and cytoplasmic free calcium level changes induced by elastin peptides in human endothelial cells
G FAURY, Y USSON, M ROBERT-NICOUD, L ROBERT, AND J VERDETTI.
Institut Albert Bonniot, Universite´ J. Fourier, Grenoble, Fr; and Universite´ Paris, Paris, Fr
PNAS: Cell Biology 1998; 95: pp. 2967–2972.
The extracellular matrix protein ‘‘elastin’’ is the major component of elastic fibers present in the arterial wall. Physiological degradation of elastic fibers, enhanced in vascular pathologies, leads to the presence of circulating elastin peptides (EP). EP have been demonstrated to influence cell migration and proliferation. EP also induce, at circulating pathophysiological concentrations (and not below), an endothelium-and NO- dependent vasorelaxation mediated by the 67-kDa subunit of the elastin-laminin receptor. Here, by using the techniques of patch-clamp, spectrofluorimetry and confocal microscopy, we demonstrate that circulating concentrations of EP activate low specificity calcium channels on human umbilical venous endothelial cells, resulting in increase in cytoplasmic and nuclear free calcium concentrations. This action is independent of phosphoinositide metabolism. Furthermore, these effects are inhibited by lactose, an antagonist of the elastin-laminin receptor, and by cytochalasin D, an actin microfilament depolymerizer. These observations suggest that EP-induced signal transduction is mediated by the elastin-laminin receptor via coupling of cytoskeletal actin microfilaments to membrane channels and to the nucleus. Because vascular remodeling and carcinogenesis are accompanied by extracellular matrix modifications involving elastin, the processes here described could play a role in the elastin-laminin receptor-mediated cellular migration, differentiation, proliferation, as in atherogenesis, and metastasis formation.
Part 5. Regulation of the Cytoskeleton
5a Regulation of the Actin Cytoskeleton by PIP2 in Cytokinesis
MR Logan and CA Mandato
McGill University, Montreal, Ca
Biol. Cell (2006) 98, 377–388 [doi:10.1042/BC20050081]
Cytokinesis is a sequential process that occurs in three phases:
assembly of the cytokinetic apparatus,
furrow progression and
fission (abscission) of the newly formed daughter cells.
The ingression of the cleavage furrow is dependent on the constriction of an equatorial actomyosin ring in many cell types. Recent studies have demonstrated that this structure is highly dynamic and undergoes active polymerization and depolymerization throughout the furrowing process. Despite much progress in the identification of contractile ring components, little is known regarding the mechanism of its assembly and structural rearrangements. PIP2 (phosphatidylinositol 4,5-bisphosphate) is a critical regulator of actin dynamics and plays an essential role in cell motility and adhesion. Recent studies have indicated that an elevation of PIP2 at the cleavage furrow is a critical event for furrow stability. We discuss the role of PIP2-mediated signaling in the structural maintenance of the contractile ring and furrow progression. In addition, we address the role of other phosphoinositides, PI(4)P (phosphatidylinositol-4-phosphate) and PIP3 (phosphatidylinositol 3,4,5-triphosphate) in these processes.
Regulation of the actin cytoskeleton by PIPKs (phosphatidylinositol phosphate kinases) and PIP2 (phosphatidylinositol 4,5-bisphosphate)
PIP2 is generated by the activity of type I (PIPKIs) or type II (PIPKII) kinase isoforms (α, β, γ) which utilize PI(4)P (phosphatidylinositol 4-phosphate) and PI(5)P (phosphatidylinositol 5-phosphate) as substrates respectively. PIPKIs are localized to the plasma membrane and are thought to account for the majority of PIP2 synthesis, whereas PIPKIIs are predominantly localized to intracellular sites. PIP2 plays a key role in re-structuring the actin cytoskeleton in several ways. In general, high levels of PIP2 are associated with actin polymerization, whereas low levels block assembly or promote actin severing activity. PIP2 facilitates actin polymerization in multiple ways such as:
(i) activating N-WASp (neuronal Wiskott–Aldrich syndrome protein)- and Arp2/3 (actin-related protein 2/3)-mediated actin branching, (ii) binding and impairing the activity of actin-severing proteins, such as gelsolin and cofilin/ADF (actin depolymerizing factor); and (iii) uncapping actin filaments for the addition on new actin monomers
This polymerization signal is counteracted by the generation of IP3 (inositol 1,4,5-triphosphate) and DAG (diacylglycerol), following PLC (phospholipase C)-mediated hydrolysis of PIP2. IP3-mediated activation of Ca2+/CaM (calmodulin) promotes the activation of severing proteins such as gelsolins and cofilin, which lead to solubilization of the actin network (Figure 1). In addition to influencing actin polymerization, PIP2 modulates the function of several actin cross-linking and regulatory proteins which are critical for the assembly of stress fibres, gel meshworks and membrane attachment. For example, PIP2 negatively regulates cross-linking mediated by filamin and the actin-bundling activity of α-actinin. In contrast, PIP2 induces conformational changes in vinculin, talin and ERM (ezrin/radixin/moesin) family proteins to promote anchoring of the actin cytoskeleton to the plasma membrane. PLC-mediated hydrolysis of PIP2 and the downstream activation of Ca2+/CaM and PKC (protein kinase C) also influences actin-myosin based contractility. Ca2+/CaM activates MLCK (myosin regulatory light chain kinase), leading to phosphorylation of the MLC (myosin regulatory light chain). Similarly, PKC has been shown to phosphorylate and activate MLC (Figure 1).
Figure 1 Summary of PIP2-mediated regulation of the actin cytoskeleton
Role of PIP2-mediated signaling in cell division
Prior to cell division cells undergo a global cell rounding which is a prerequisite step for the initiation of the cleavage furrow. In frog, sea urchin and newt eggs these shape changes correlate with an increase in cortical tension that precedes or occurs near the onset of the cleavage furrow. Precise mapping of the changes in cortical tension have shown that peaks of tension are propagated in waves that occur in front of and at the same time as furrow initiation. These tension waves are generated by actomyosin-based contractility and subside after the furrow has passed. Experiments in Xenopus eggs, zebrafish and Xenopus embryos indicated that site-specific Ca2+ waves were generated within the cleavage furrow that would be predicted to coincide with peaks of cortical tension. The injection of heparin, a competitive inhibitor of IP3 receptors, or Ca2+ chelators were both demonstrated to significantly delay or arrest furrowing , and a similar inhibitory effect was observed of microinjected PIP2 antibodies that caused a depletion of the intracellular pool of DAG and Ca2+ in Xenopus blastomeres. In addition, the increase in cortical contractility of Xenopus oocytes has been shown to occur via a PKC-dependent pathway. Together, these studies demonstrate a role for PIP2-mediated signaling at the early stages of cytokinesis.
Recent studies have supported that PIP2-mediated signaling also plays a critical role in ingression of the cleavage furrow, although significant differences have been shown in the localization of PIP2 and the role of PLC. Lithium and the PLC inhibitor, U73122, caused a rapid (within minutes) regression of cleavage furrows in crane fly spermatocytes, but did not block their initial formation. PIP2 may become concentrated within the cleavage furrow and could facilitate anchoring of the plasma membrane to structural components of the actomyosin ring. A PIPKI homologue, its3, and PIP2 were reported at the septum of dividing fission yeast, Schizosaccharomyces pombe. A temperature sensitive mutant of its3 exhibited disrupted actin patches, following a shift to the restrictive temperature, and also impaired cytokinesis. Although a contractile ring was still evident in these cells, abnormalities, such as an extra ring, were found. Two recent studies demonstrated an increase in PIP2-specific GFP-labeled PH domains within the cleavage furrow of mammalian cells. Both of these reports suggested de novo synthesis of PIP2 occurs within the furrow. Another study found that endogenous and over-expressed PIPKIβ, but not PIPKIγ, concentrated in the cleavage furrow of CHO (Chinese hamster ovary) cells. The expression of a kinase-dead mutant of this isoform and microinjection of PIP2-specific antibodies both caused a significant increase in the number of multinucleated cells. A multinucleated phenotype was, similarly, observed in multiple cell lines (CHO, HeLa, NIH 3T3 and 293T) transfected with high levels of PIP2-specific PH domains, synaptojanin [which dephosphorylates PIP2 to PI(4)P], or a kinase-dead mutant of PIPKIα. In addition, a small percentage of CHO and HeLa cells expressing high levels of PIP2-specific PH domains or synaptojanin showed signs of F-actin dissociation from the plasma membrane. CHO cells transfected with PIP2 PH domains, but not PH domains specific for PI(3,4)P2 (phosphatidylinositol 3,4-bisphosphate) and PIP3, also exhibited impaired furrow expansion induced by the application of hypotonic buffer. This suggests one of the primary roles of PIP2 is to promote cytoskeleton–membrane anchoring at the furrow.
Role of PI3Ks (phosphoinositide 3-kinases) and PI4Ks (phosphoinositide 4-kinases) in cytokinesis PI4Ks generate the PIPKI substrate, PI(4)P, and play a critical role in PIP2 generation. Studies in lower organisms support the requirement of PI4Ks for cytokinesis. In Saccharomyces cerevisiae two PI4Ks, STT4 and PIK1, have non-overlapping functions in Golgi-tomembrane trafficking and cell-wall integrity respectively. Both genes are also required for cell division. Conditional mutants of Pik1p exhibited a cytokinesis defect: cells arrest with large buds and fully divided nuclei. In addition, STT4 was identified as a gene implicated in reorientation of the mitotic spindle prior to cytokinesis. Spermatocytes derived from fwd mutant males had unstable furrows that failed to ingress and abnormal contractile rings with dissociated myosin II and F-actin, fwd has homology with yeast PIK1 and human PI4KIIIβ. Although PIK1 is an essential gene in yeast, the deletion of fwd was not lethal and female flies were fertile. A study in fission yeast suggests that PI4Ks may be recruited to the furrow, as reported for PIPKs. Desautels et al. (2001) identified a PI4K as a binding partner of Cdc4p, a contractile ring protein with homology to the myosin essential light chain. A Cdc4p mutant, G107S, abolished the interaction with PI4K and induced the formation of multinucleated cells with defects in septum formation. This finding suggests that, at least for fission yeast, anchoring of PI4K to the contractile ring may concentrate PI(4)P substrate within the furrow for subsequent PIP2 generation.
An increased synthesis of PIP2 by PIPKIs at the cleavage furrow is anticipated to promote both actin polymerization and structural support to the contractile ring. Structural proteins of the contractile ring regulated by PIP2 include anillin, septin and ERM proteins. The concentration of PIP2 at the cleavage furrow is postulated to be a critical molecule in the recruitment of these proteins and their integration with the actomyosin ring. Anillin exhibits actin-bundling activity and is required at the terminal stages of cytokinesis in Drosophila and human cells. The depletion of anillin in Drosophila and human cells causes cytokinesis failure, which is correlated with uncoordinated actomyosin contraction of the medial ring. Anillin also functions as a cofactor to promote the recruitment of septins to actin bundles. Mutations within the PH domain of anillin were recently demonstrated to impair septin localization to both the furrow canal and the contractile ring in Drosophila cells, blocking cellularization and furrow progression. Septins have also been shown to bind to phosphoinositides and this interaction regulates their subcellular localization. The mammalian septin, H5, bound PIP2 and PIP3 liposomes at its N-terminal basic region, which is conserved in most septin proteins. The over-expression of synaptojanin and treatment with neomycin (which depletes cellular PIP2) both caused disruption of actin stress fibres and dissociation of H5 from filamentous structures in Swiss 3T3 cells. Septins are co-localized with actin at the cleavage furrow and form ring structures that are postulated to structurally support the contractile ring.
Studies suggest that PLC-mediated hydrolysis of PIP2 and the subsequent release of intracellular Ca2+ stores is a necessary event for furrow stability and ingression. A role for Ca2+ is similarly supported by previous findings that Ca2+ waves were localized to the cleavage furrow in frog embryos, eggs and fish. PLC second messengers have also been implicated in cytokinesis. For example, CaM was localized to mitotic spindles of HeLa cells and the inhibition of its activity was reported to cause cytokinesis defects. A recent RNAi (RNA interference) screen also identified PI4Ks and PIPKs, but not PLC genes, as critical proteins for cytokinesis in Drosophila. This may indicate PLC is required for completion of furrowing, rather than its initiation.
It is hypothesized that PLC activity may promote actin filament severing through the activation of Ca2+-dependent actin-severing proteins, such as gelsolin and cofilin. Depending on the localization of PLC, this could either drive disassembly of actin filaments of the medial ring or the cortical actin network. Furthermore, the activation of PKC and CaM would activate actomyosin contraction via the phosphorylation of MLCK. At the furrow, PKC and CaM could act in concert with the Rho effectors ROCK and Citron kinase, which also phosphorylate and activate MLC.
The activation of CaM and/or PKC may also provide positive feedback for the recruitment of PIP2 effectors and regulate GTPase-mediated actin polymerization. Both PKC and CaM have been shown to promote the dissociation of MARCKS (myristoylated alanine-rich C kinase substrates) family proteins from PIP2. MARCKS are postulated to play a major regulatory role in phosphoinositide signalling by sequestering PIP2 at the membrane. Thus the activation of PKC and CaM promotes PIP2 availability for the recruitment of PH-domain-containing effector proteins. Studies in yeast and mammalian cells have supported that CaM and PKC can mediate positive feedback for PIP2 synthesis by activating PIPKs.
Signaling Crosstalk: Role of GTPases and Phosphoinositides
On the basis of the present available data, PIP2 has been shown to be a critical molecule for structural integrity of the contractile ring and furrow stability. However, the observation that furrows are initiated in cells treated with agents that either sequester PIP2 or prevent its hydrolysis suggests PIP2 does not provide the originating signal for furrow formation. Recent studies suggest that the recruitment and activation of RhoA may provide this early signal.
Figure 2 Proposed model of PIP2 and GTPase signaling at the cleavage furrow
Ect2, is recruited to the cleavage furrow via its interaction withMgcRacGAP at the central spindle. Ect2 and MgcRacGAP regulate the activities of Rho GTPases (RhoA, Cdc42 and Rac) and are functionally implicated in the assembly of the contractile ring. Active RhoA and Cdc42 are increased at the furrow, whereas Rac is suppressed (grey). Furrow-recruited GTPases (RhoA, ARF6 and Cdc42) are predicted to activate PIPKI, leading to the generation of PIP2. PI3K activity is suppressed at the furrow (grey), which may be due to MgcRacGAP-mediated inhibition of Rac and/or the activity of the PIP3 phosphatase, PTEN. Cycles of PIP2 synthesis and hydrolysis by PLC are thought to play a critical role in re-structuring the contractile ring throughout the duration of furrowing. PIP2-mediated activation of anillin, septins and ERM proteins promotes cross-linking and membrane anchoring of the contractile ring. PLC-mediated activation of PKC and CaM can facilitate the contraction of the actomyosin ring, similar to RhoA effectors, ROCK and Citron kinase. CaM may also regulate IQGAP–Cdc42 interactions, and thereby modulate actin organization. It is hypothesized that Cdc42-mediated actin polymerization via effectors, such as N-WASp (neuronalWiskott–Aldrich syndrome protein) and Arp2/3 (actin-related protein 2/3), may reduce membrane tension outside the inner region of RhoA-mediated contractility.
English: Diagram showing Actin-Myosin filaments in Smooth muscle. The actin fibers attach to the cell wall and to dense bodies in the cytoplasm. When activated the slide over the myosin bundles causing shortening of the cell walls (Photo credit: Wikipedia)
English: Figure 2: The matrix can play into other pathways inside the cell even through just its physical state. Matrix immobilization inhibits the formation of fibrillar adhesions and matrix reorganization. Likewise, players of other signaling pathways inside the cell can affect the structure of the cytoskeleton and thereby the cell’s interaction with the ECM. (Photo credit: Wikipedia)
Groundbreaking for the future campus will begin early next year on Roosevelt Island, a quiet, residential two-mile strip of land between Manhattan and Queens in the East River. As part of Mayor Bloomberg’s 2011 initiative, Cornell Tech was awarded a 99-year lease to the 12.5-acre site along with $100 million in city capital for site maintenance and construction. Cornell’s plans to build and develop the campus include demolition of the island’s Coler-Goldwater Specialty Hospital & Nursing Facility. The new campus will include up to 2.1 million square feet of development and will house approximately 2,000 students and 280 faculty members by 2037.
Cornell NYC Tech by the numbers; click to enlarge (Source: nyc.gov)
Dan Huttenlocher, Dean and Vice Provost of Cornell Tech, told MetroFocus host Rafael Pi Roman the most challenging part of the process has been “…getting the culture right. We’re building a new organization. That organization is really intended to be a model for the world, to bring together academic excellence and academic leadership with real world impact.”
Cornell chose the Technion-Israel Institute of Technology in Haifa as its international partner. Craig Gotsman, Founding Director of theJoan and Irwin Jacobs Technion-Cornell Innovation Institute, told Pi Roman, “one of the reasons the Technion is involved in the first place, is that the innovation and the entrepreneurship that you see in Israel is something that the city of New York wants to have here in New York City.” The New York Times reports that Technion graduates in high-tech industries have an annual estimated output of at least $21 billion. While the partnership has been at times controversial, The Cornell Daily Sun reports that Cornell Provost Kent Fuchs has said the partnership “is intended not as a political statement, but rather as an opportunity for the University to foster global academic cooperation.”
We’re building a new organization. That organization is really intended to be a model for the world, to bring together academic excellence and academic leadership with real world impact.
—Dan Huttenlocher
The City of New York will act as a “third partner” in the campus by connecting students and faculty directly to businesses in the city’s growing tech sector. In recent years, the city has risen as a success story in the tech community. According to The Center for an Urban Future‘s recent report “New Tech City,” the number of information technology jobs in the city climbed 60% in less than ten years – from 33,000 in 2003 to 52,900 in 2012. “New Tech City” also reported that the number of venture capital deals in New York rose by 32% in that period, while it fell by about 11% across the nation. Today, Mayor Bloomberg’s economic development initiative, “We Are Made in New York,” reports that over 1,000 city tech companies are currently hiring.
The plans for Cornell Tech have prompted debates about whether New York’s “Silicon Alley” will become a force to rival California’s Silicon Valley. When asked whether Cornell [NYC] Tech will help the city surpass Silicon Valley’s tech economy, Huttenlocher noted that it’s more about identifying and harnessing the city’s strengths to set New York apart from other high-tech sectors around the world. “We’re the center of so many of these information-rich industries, bringing real technology expertise here, on the ground, in New York City, we think is a unique opportunity for New York to lead in the next century of information technology development,” said Huttenlocher.
“Privacy, Security & Your Data – Concerns in a Changing World” – Streamed LIVE: Tuesday, June 18th – 6:45pm (EDT)
Reporter: Aviva Lev-Ari, PhD, RN
Streamed LIVE: Tuesday, June 18th – 6:45pm (EDT)
“Privacy, Security & Your Data – Concerns in a Changing World”
In this fast paced, technological world, our personal information is vulnerable every single day. As companies grow globally, and cyber security becomes ever more challenging, how do businesses preserve individual privacy and maintain the security of personal data?
Presented by Cornell University and Hunton & Williams LLP, please join us for a livestream event, broadcasted from New York City.
To tune in, visit our Livestream page a few minutes before the broadcast.
*Please base your start time on your specific time-zone.
Keynote: The Changing Landscape of Lawful Access (30min)
Panel: Hot topics in Global Privacy and Data Security (60min)
Speakers:
Keith Enright, Senior Privacy Counsel, Google
Mark Fasciano ’90, Managing Director & Internet Entrepreneur, Canrock Ventures
Tracy Mitrano JD ’95, Director of IT Policy and Institute for Computer Policy and Law, Cornell University
Lisa Sotto ’84, Head, Privacy and Data Security Practice, Hunton & Williams LLP
JoAnn Stonier, SVP/Global Privacy & Data Usage Officer, MasterCard Worldwide
Stephen B. Wicker, Professor of Electrical and Computer Engineering, Cornell University
This program is generously hosted by Lisa Sotto ’84 and Hunton & Williams LLP
**If you hold a senior level postion in the privacy space and this topic directly reflects your day-to-day work, there may be limited in-person space available on Tuesday due to cancellations. Please contact John Zelenka ’03, MBA ’12 at jfz4@cornell.edu for additional information.
“There is a whole economy behind writing fraudulent reviews, and people paying these review writers,” explained Gupta, an assistant professor of computer science.
The researchers pointed out a website called fiverr.com , where everything sells for five dollars: including fraudulent reviews.
One post says, “I will buy your Amazon product and write your review for five dollars.”
Another states, “I will do post two nice and attractive Amazon reviews.”
For their study, Gupta and Hoyle bought 55 reviews for different products they found on Amazon.
“We took all their fraudulent reviews, and then we studied their characteristics,” explained Gupta.
They found the people who were writing the reviews for money were from all over the world: from the U.S, to Ireland, to India, to Bangladesh.
“In general, it is getting harder to distinguish good from the bad on the web,” said Gupta.
They say there are clues to help consumers understand what’s real and what’s fake.
Gupta and Hoyle recommend looking on Amazon for a label on reviews: “Amazon Verified Product.” That means the reviewer actually bought the product, and the review is more likely real.
They recommend looking at what else the reviewer has written. Hoyle found one reviewer copy and pasted the same review on multiple CDs.
Another potential warning sign: If a reviewer gives all five-star reviews within a short period of time. They may be getting paid to post positive reviews.
“You have to use a lot more judgment, and increasingly the notion of reputation will become more and more important,” said Gupta. “We are starting to see this.”
In Gupta and Hoyle’s study, they estimate 257,000 reviews on Amazon (or about 1 percent) are fraudulent. Their goal long-term is to develop a program to entirely eliminate fake reviews.
Rob Slaven reviews books — not for the money, but for the love of reading. He gets to keep every book he reviews.
“The books I’ve reviewed, I’ve tried to be devastatingly honest,” said Slaven.
If you look at all of his reviews, you’ll see a line he adds, disclosing he got the book for doing the review. He also gets feedback — positive and negative — for each review he posts.
He knows not everyone is as honest as he is, but says he’ll keep up his side of the bargain.
“I’m not going to say something that’s not true,” explained Slaven. “It would be me misleading people. Me, misleading people like me.”
Review sites say they’re fighting fraud. Yelp representatives say they’ve always had a review filter to keep fake content out. They also recently started posting a giant red “consumer alert” sign on businesses that tried to mislead people. Amazon also has a flagging system.
But, researchers say not all fake reviews are caught. It’s a disappointing, but not surprising, revelation for honest reviewers.
“Customers go on Amazon in order to get trustworthy reviews, and to get candid opinions,” said Slaven.
Federal Trade Commission spokeswoman Betsy Lordan tells 24-Hour News 8 that paying for online reviews is legal, as long as the reviewer explains they’ve been compensated.
Of course, with the reviews 24-Hour News 8 discovered, there’s been no disclosure.
Dr. Irwin Jacobs, Co-Founder, Chairman and CEO Emeritus of Qualcomm, was honored on May 20 with the Technion Medal, the greatest recognition by the Technion-Israel Institute of Technology, awarded only every three to five years. He received the medal during a festive event in Haifa, marking 20 years of Qualcomm activities in Israel.
Technion President Professor Peretz Lavie spoke about the long-standing friendship with the Technion and generous philanthropic activities of Dr. Jacobs and his wife Joan. The Technion’s Graduate School is named for them, as is the Center for Communications and Information Technologies (CCIT). Those gifts have supported Technion graduate students — arguably the engine behind any successful university— and have helped the CCIT promote cooperation and information flow between academia and industry. Recently, they made a $133 million gift to name the Joan and Irwin Jacobs Technion-Cornell Innovation Institute (JTCII), a key component of the new applied science campus in New York.
(From left) Technion President Peretz Lavie, and Joan and Irwin Jacobs
President Lavie expressed his appreciation to Dr. Jacobs: “Thank you so very much for all you have done for the Technion, engineering, the field of telecom, academia, Israel, and future scientists. You are truly a great leader, model citizen, and a real ‘mensch.’”
Dr. Jacobs returned the gratitude, saying it is not the Technion that needs to thank him, but rather he who needs to thank the Technion. “Many of Qualcomm’s employees are Technion graduates,” he said. “The company would not have attained many of its achievements if it hadn’t been for its brilliant employees.”
In 1993, Dr. Jacobs directed the then still young, San Diego-based digital wireless telecommunications company to launch Qualcomm Israel in Haifa to take advantage of Technion brainpower (the Mt. Carmel campus is about a 15-minute drive). Since then, Qualcomm Israel has become a key source of high-tech innovation in Israel, moving into such creative ventures as “Tagg,” a device that allows pet owners to track their pet’s location and activity level. Qualcomm’s recent investments in Israeli start-ups rival similar activities in all of Europe.
The Technion Medal was established in 1996 to award “exceptional individuals who have made unstinting efforts to advance humanity; … contribute to the welfare of the Jewish people and the State of Israel; and … strengthen the industrial, scientific and economic infrastructure of Israel.” Irwin Jacobs joins a short list of just 12 other Technion Medal recipients that includes Israel Supreme Court Justice Moshe Landau and Israeli war hero Gen. (Res.) Amos Horev — both former Technion Presidents; Technion graduate Uzia Galil, one of the founders of Israel’s high-tech industry, and the late Henry Taub, who held almost every honor and position within the American Technion Society (ATS), including national President and Chair of the Technion International Board of Governors for 13 years.
Dr. Jacobs earned his bachelor’s degree in electrical engineering from Cornell University and his master’s and doctorate degrees in electrical engineering and computer science from the Massachusetts Institute of Technology (MIT). He taught at both MIT and at University of California, San Diego, co-authored an engineering textbook and co-founded Linkabit Corporation, before helping start Qualcomm. The Technion recognized Dr. Jacobs with an honorary doctorate in 2000, and in 1996, the American Technion Society (ATS) granted him its highest honor, the Albert Einstein Award. He and his wife are Technion Guardians — a designation reserved for those who have reached the highest level of support.
The Technion-Israel Institute of Technology is a major source of the innovation and brainpower that drives the Israeli economy, and a key to Israel’s renown as the world’s “Start-Up Nation.” Its three Nobel Prize winners exemplify academic excellence. Technion people, ideas and inventions make immeasurable contributions to the world including life-saving medicine, sustainable energy, computer science, water conservation and nanotechnology. The Joan and Irwin Jacobs Technion-Cornell Innovation Institute is a vital component of Cornell NYC Tech, and a model for graduate applied science education that is expected to transform New York City’s economy.
American Technion Society (ATS) donors provide critical support for the Technion—more than $1.9 billion since its inception in 1940. Based in New York City, the ATS and its network of chapters across the U.S. provide funds for scholarships, fellowships, faculty recruitment and chairs, research, buildings, laboratories, classrooms and dormitories, and more.
Mayor Bloomberg Officially Transfers 12 Acres of Roosevelt Island to “Cornell Tech” – Technion-Cornell’s Jacobs Technion-Cornell Innovation Institute (JTCII)
Mayor Bloomberg, Cornell University President David J. Skorton, and Technion-Israel Institute of Technology President Peretz Lavie today formally executed a 99-year lease between the City of New York and Cornell Tech, which will pave the way for construction of the Cornell Tech campus on Roosevelt Island, exactly two years after Cornell and academic partner Technion were named the first winners of the City’sApplied Sciences NYC competition.
Cornell Tech is a revolutionary model for graduate-level technology education and is establishing itself as a world-leading institution, conferring graduate degrees and conducting research that drives technology, innovation, commercialization and the creation and retention of businesses and jobs in New York City. The land transfer will allow for groundbreaking on the campus to begin in January, with the first classrooms on Roosevelt Island set to open in 2017. Cornell Tech students began classes this fall in space donated by Google at their Chelsea headquarters on Eighth Avenue. Construction of the entire 2 million square foot build-out, which will span 12 acres on Roosevelt Island and house approximately 2,000 students and nearly 280 faculty and researchers, will be completed by 2043.
New details and renderings for the first phase of the full campus were also released today, revealing how the physical campus will be designed to support Cornell Tech’s focus on innovation, entrepreneurship and collaboration between academia and industry. Mayor Bloomberg and President Skorton signed the lease documents at a City Hall ceremony to finalize the official land transfer to Cornell Tech, where they were joined by President Lavie, Deputy Mayor for Economic Development Robert K. Steel, New York City Economic Development Corporation President Kyle Kimball, U.S. Representative Carolyn Maloney, Council Member and Borough President-Elect Gale Brewer, Council Member Jessica Lappin, Cornell Tech Vice President Cathy Dove, Cornell Board Chair Robert Harrison, Cornell Provost Kent Fuchs, Cornell Tech Dean Daniel Hutenlocher, Forest City Ratner Companies President and CEO MaryAnne Gilmartin, and Hudson Companies Principal David Kramer.
“Our goal has been to make New York City the global capital of technological innovation, and this new campus on Roosevelt Island is a central part of our strategy for achieving it,” said Mayor Michael R. Bloomberg. “It is one of the most ambitious and forward-looking economic development projects any city has ever undertaken, and it’s going to help add thousands of new jobs to our economy in the decades ahead.”
“The State was proud to work closely with the Mayor’s Office, RIOC and Cornell because we strongly believe that the path to New York State’s continued economic growth will largely be defined by partnerships that start with our State’s academic institutions,” said Governor Andrew M. Cuomo. “This project leverages two of the world’s most notable institutions in a way that will help foster technological innovation within New York State, while creating jobs and spurring business investment.”
“Cornell Tech is the proof that government and universities can work together to innovate and support economic growth, and we will be forever grateful for Mayor Bloomberg’s leadership in making this campus possible,” said Cornell University President David J. Skorton. “The Roosevelt Island campus is being built for the future, to be the place that generates the next big ideas, the new companies and extraordinary talent that will change New York and the world.”
“Thanks to Mayor Bloomberg’s vision, New York City is fast becoming a leading global center of innovation,” said Technion President Peretz Lavie. “Through the Joan & Irwin Jacobs Technion-Cornell Innovation Institute, our international partnership with Cornell Tech, we look forward to helping to further the city’s future as the technology capital of the world.”
Applied Sciences NYC was launched by Mayor Bloomberg in 2011 in an effort to capitalize on the considerable recent growth and even larger opportunity for future growth in technology-related jobs and businesses in New York City, and builds on the Bloomberg Administration’s record of creating a more diversified economy for the City’s future. In July 2011, NYCEDC issued an RFP seeking a university, institution or consortium to develop and operate a new or expanded campus in the City in exchange for City capital, access to City-owned land and the full support and partnership of the Bloomberg Administration, and subsequently received seven responses from 17 world-class institutions from around the globe. Cornell Tech was the first of four Applied Sciences projects to be announced by the City in an effort to strengthen New York City’s global competiveness – including its growing technology sector – and ensure that the City establishes itself as a worldwide hub of science, research, innovation and urban solutions for the digital age and the information economy. Cornell Tech was selected for this initiative based on its innovative model for graduate technology education and its emphasis on the intersections between academia and industry and forward-thinking areas of study. When completed, the new Roosevelt Island campus alone will nearly double the number of full-time, graduate engineering students enrolled in leading New York City Master’s and Ph.D. programs.
The four Applied Sciences NYC projects that have been announced by the Mayor include:
Cornell Tech on Roosevelt Island
The Center for Urban Science and Progress in Downtown Brooklyn, operated by an international consortium led by New York University
The Institute for Data Sciences and Engineering at Columbia University
Carnegie Mellon University’s Integrative Media Program at Steiner Studios in the Brooklyn Navy Yard.
Collectively, the four Applied Sciences NYC projects are expected to generate more than $33.2 billion in nominal economic activity, over 48,000 permanent and construction jobs, and approximately 1,000 spin-off companies by 2046, fulfilling the initiative’s goal of dramatically transforming the City’s economy for the 21st century. These institutions are already strengthening the City’s position as a hub of science, research, innovation and world-class urban solutions in a global economy driven by technological fluency and innovation.
“Mayor Bloomberg’s Applied Sciences initiative will transform the City’s economy, doubling the number of engineering faculty and graduate students in New York City. These are the skills we need to compete in the knowledge and information economy of the 21st Century,” said Deputy Mayor for Economic Development Robert K. Steel. “The closing of the Cornell Tech lease is a major step toward that goal and I congratulate Presidents Skorton and Lavie on this critical moment in the arc of Cornell and the Technion’s history.”
“Over only two years, thanks to an unprecedented model of collaboration across City and State government, top academic institutions, and the private sector, we have transformed Applied Sciences NYC from a visionary idea into a physical reality that is already reshaping our City,” said NYCEDC President Kyle Kimball. “Since selecting Cornell and the Technion as our first winners, in partnership with the Health and Hospitals Corporation we have built and opened a new hospital in Harlem that is currently serving former Coler-Goldwater patients; secured all necessary approvals for the Roosevelt Island campus; selected three additional Applied Sciences winners; and launched classes. Thanks to Mayor Bloomberg’s leadership, this initiative will create jobs, businesses, and technologies, resulting in transformative economic activity that will help secure the City’s future.”
“Cornell Tech is extremely grateful for the unwavering support of the Roosevelt Island community throughout the public review process and we are committed to being great neighbors during construction and beyond,” said Cornell Tech Vice President Cathy S. Dove. “We are also fortunate to have such extraordinary development partners in Forest City Ratner and Hudson/Related to help us make this vision a reality.”
“We are thrilled to be working with Cornell and so many great partners to help create a truly extraordinary new place on Roosevelt Island,” said Forest City Ratner Companies President and CEO MaryAnne Gilmartin. “Under Mayor Bloomberg’s watch the City’s tech sector has grown enormously and we are well poised as a company and as a project to continue with that growth at Cornell Tech.”
“With Mayor Bloomberg’s vision guiding the way, Cornell Tech will be at the leading edge of the next generation in tech and applied sciences,” said David Kramer, partner of The Hudson Companies. “We look forward to bringing out-of-the-box thinking to a best-in-class building on the forefront of design and sustainability.”
“I am pleased to join Mayor Bloomberg for this monumental step toward making the Cornell Tech campus a reality. I have strongly supported bringing Cornell Tech to Roosevelt Island from the very beginning of this process,” said U.S. Representative Carolyn Maloney. “The campus holds great promise for Roosevelt Island and for New York City, attracting future leaders in the technology and engineering industry. Many of the amenities included in the plans will be open and available to the public, including areas of park space. I commend Cornell for its transparency during the planning process and commitment to being a good neighbor to Island residents.”
“Cornell Tech will generate opportunities and innovations for generations to come, and today we take a step closer to our city’s future,” said Council Member Jessica Lappin.
“I applaud Mayor Bloomberg, Cornell Tech, and the Roosevelt Island Operating Corporation on their historic lease signing to build a new applied sciences campus on Roosevelt Island,” said Manhattan Borough President-Elect Gale A. Brewer. “This partnership will play a key role in the growth of New York City’s tech sector in the coming years, and will attract new development to Roosevelt Island. I look forward to working with all parties to ensure the success of this venture.”
Academic uses of the campus are anticipated to include classrooms, laboratories, teaming areas, and lecture halls, as well as start-up incubator/accelerator space to encourage entrepreneurship. The remainder of the space in the campus will be devoted to corporate co-location space designed to facilitate the interaction between academia and industry, residential uses, an executive education center, and ancillary uses, such as retail in support of the faculty, staff and students on the campus, as well as the creation of new open space.
While planning is underway for the opening of the permanent campus in 2017, Cornell Tech is already operating in temporary space in Manhattan. The campus master plan, designed by Skidmore, Owings and Merrill with James Corner Field Operations, includes a number of innovative features and facilities across a river-to-river campus with expansive views, a series of green, public spaces, and a seamless integration of indoor and outdoor areas. Cornell Tech will combine cutting edge technologies to create one of the most environmentally friendly and energy-efficient campuses in the world, not only employing, but developing new environmental technology.
A sustainable and innovative academic building will be designed by Pritzker Prize-winning architect Thom Mayne of Morphosis Architects and, in a significant departure from traditional academic facilities, take its cue from the tech world by offering open-plan space and extensive collaborative workspaces. The phase one academic building, if completed today, would be the largest net-zero energy building in eastern United States, with all of its power generated on campus.
A corporate co-location building, designed by Weiss/Manfredi and developed by Forest City Ratner Companies, will bring together corporate innovators, world-class researchers and energetic start-ups under one roof, a concrete reflection of the campus’ mission of fusing academia and industry to encourage innovation for the public good. Cornell Tech will be an anchor tenant. Renderings of this building and the academic building were released today, and are available at tech.cornell.edu/press/.
Ensuring that the campus is active 24/7, a residential building, designed by Handel Architects and developed by Hudson and Related Companies, will be built to provide convenient and affordable campus housing for students, faculty and staff. It will rely on passive sustainable design features to reduce energy usage and further advance the campus’ sustainability goals.
Plans are also under underway for an Executive Education Center and Hotel, which will help ensure that Cornell Tech is a magnet in New York City for innovation by providing conference, executive program and academic workshop space along with a hotel and destination restaurant.
The 12-acre footprint of the Cornell Tech campus includes the site of the former Goldwater Specialty Hospital and Nursing Facility, which has been replaced by the new state-of-the art, 365-bed, $300 million Henry J. Carter Specialty Hospital in Harlem, built by NYCEDC, which is operated by the NYC Health and Hospitals Corporation and provides world-class medical care for New Yorkers in need of highly specialized, complex treatment. Former Goldwater patients were relocated to the new hospital last month. The campus footprint also includes property formerly controlled by the Roosevelt Island Operating Corporation. Cornell Tech has spent the past year working with the Roosevelt Island community on plans to minimize the impact of construction on residents, including deployment of the largest barging program in New York City to remove demolition materials from the site.
Cornell Tech classes began earlier this year in space donated by Google in Chelsea. The school now includes masters and Ph.D. students, world-class faculty and established collaborations with dozens of industry-leading organizations contributing to graduate study in areas such as Computer Science, Electrical and Computer Engineering, Information Science, Operations Research and Business. Cornell Tech also launched its commitment to partnership with New York City’s public school students earlier this year, working with numerous organizations to bring tech education to a diverse audience. A director of K-12 education for Cornell Tech will be announced early in 2014.
Beginning in January, the Joan and Irwin Jacobs Technion-Cornell Innovation Institute at Cornell Tech will welcome a number of postdoctoral students to the current campus. Later in 2014, the Jacobs Institute will launch a master’s degree program in Connective Media designed to educate the entrepreneurial engineers and technologists needed in the media sector to steward the continuing digital transformation of the industry. Students in this two-year program will receive degrees from both Technion and Cornell. Also in 2014, Cornell Tech will launch a Johnson MBA that will combine business, technology, innovation and entrepreneurship in a fast-paced, hands-on learning environment.
Cornell Tech will host entrepreneurs-in-residence, organize business competitions, provide legal support for startups, reach out to existing companies to form research partnerships and sponsor research, and establish a pre-seed financing program to support promising research. In addition, the campus will structure its on-site tech transfer office to facilitate startup formation and technology licensing. Cornell Tech will also invest $150 million that will be solely devoted to start-up businesses in the City.
In keeping with the focus on community involvement contained in the RFP, the Cornell Tech proposal outlined a number of areas in which the universities will touch the lives of New Yorkers — the type of involvement to which both schools have been committed for many years in their primary campus communities. Plans for community involvement in New York City include the creation of education enhancement programs that will impact a minimum of 10,000 New York City students and 200 New York City teachers per year. Cornell Tech also intends to work closely with PS/IS 217 on Roosevelt Island to enrich their curricula and participate in STEM-oriented programming. They will also work to meet the goals of the City’s HireNYC employment program and develop partnerships for job placement and training. In furtherance of its community outreach goals, Cornell Tech will offer significant programming on and off its campus designed to engage with residents of Roosevelt Island and the larger City. Cornell’s campus plan will further create new public open space on the campus.
Technion-Cornell Innovation Institute: momentous gift of $133 million to create the Joan and Irwin Jacobs Technion-Cornell Innovation Institute (JTCII)
Reporter: Aviva Lev-Ari, PhD, RN
We are pleased to share some exciting news
Irwin and Joan Jacobs on the Technion campus
Technion Guardians Joan and Irwin Jacobs, of San Diego, have made a momentous gift of $133 million to name the Technion-Cornell Innovation Institute. Dr. Irwin Jacobs, Founding Chairman and CEO Emeritus of Qualcomm, and his wife Joan will create the Joan and Irwin Jacobs Technion-Cornell Innovation Institute (JTCII). The JTCII is a key component of Cornell Tech, whose permanent campus will eventually be located on Roosevelt Island. The funds will help support curriculum initiatives, faculty and graduate students, and industry interactions in a two-year graduate program.
The gift is being announced today by New York City Mayor Michael R. Bloomberg during a press conference at New York City Hall, together with Joan and Irwin Jacobs, Technion President Peretz Lavie and Cornell President David J. Skorton. You can view the press conference at: www.nyc.gov starting at 3:00 p.m. EDT.
The Jacobses are both Cornell alumni who have a long history of supporting both institutions. Their visionary support of the Technion includes the Irwin and Joan Jacobs Graduate School and the Irwin and Joan Jacobs Center for Communications and Information Technologies. A member of the Technion International Board of Governors, Dr. Jacobs is a Life Trustee of the American Technion Society National Board of Regents, and a member of the ATS San Diego Chapter. He received the ATS’ highest honor, The Albert Einstein Award, in 1996, and a Technion Honorary Doctorate in 2000.
The JTCII plans to offer a two-year interdisciplinary program where students concurrently earn dual master’s degrees — one from Cornell and one from the Technion. This degree program will allow students to specialize in applied information-based sciences in one of three hubs focused around leading New York City industries — Connective Media, Healthier Living and The Built Environment — while honing their entrepreneurial skills. The first area of specialization will be in Connective Media, and is slated to begin in the fall of 2014. Research will also be focused on the hub areas.
A novel program for Postdoctoral Innovation Fellows will launch in fall 2013. The aim is to support individuals who seek to commercialize their research ideas in the stimulating environment of the JTCII, while taking full advantage of the entrepreneurial network of Cornell Tech and the proximity to New York City-based markets. Dr. Jacobs, along with Mayor Michael R. Bloomberg and Google Executive Chairman Eric Schmidt, serves as an advisor to Cornell Tech, the overall campus that is part of Cornell University.
Technion: Israel’s Hard Drive — as published in NY TimesIn case you missed it, The New York Times published a wonderful article about the Technion, featured on the cover page of its Education Life section on April 14, 2013. The article credits the Technion for transforming the once quiet city of Haifa into a high-tech center.Click here to read the storyClick here to read a NY Times story on Cornell Tech
The Joan and Irwin Jacobs Technion–Cornell Innovation Institute (JTCII) is an academic partnership between two of the world’s most distinguished academic institutions, the Technion – Israel Institute of Technology and Cornell University.
The JTCII is a central component of the new Cornell Tech campus in New York City. It will offer unique graduate degree programs and foster applied research by faculty, students and fellows, in collaboration with industry partners.
JOAN AND IRWIN JACOBS
On April 22, Dr. Irwin Mark Jacobs, Founding Chairman and CEO Emeritus of Qualcomm, and his wife Joan Klein Jacobs, announced a $133 million gift to Cornell University and the Technion-Israel Institute of Technology to create the Joan and Irwin Jacobs Technion-Cornell Innovation Institute.
The Jacobses are both Cornell alumni who have a long history of supporting both Cornell and the Technion-Israel Institute of Technology. They have established the Irwin M. and Joan K. Jacobs Scholars and Fellows Programs and the Irwin and Joan Jacobs Professorship, both in the College of Engineering, as well as the Joan Klein Jacobs Cornell Tradition Fellowship in the College of Human Ecology at Cornell. Dr. Jacobs is a former member of the Cornell University Council and Mrs. Jacobs served on the President’s Council of Cornell Women. In recognition of their distinguished service to Cornell, Dr. and Mrs. Jacobs were both elected Presidential Councillors in 2005. The Jacobses’ visionary support of the Technion includes the Irwin and Joan Jacobs Graduate School and the Irwin and Joan Jacobs Center for Communications and Information Technologies. A member of the Technion International Board of Governors, Dr. Jacobs is a Life Trustee of the American Technion Society National Board of Regents, and a member of the ATS San Diego Chapter. Dr. Jacobs, along with Mayor Michael R. Bloomberg and Google Executive Chairman Eric Schmidt, is a member of Cornell Tech’s Steering Committee.
Dr. and Mrs. Jacobs are among the world’s most generous philanthropists. Their support has had a significant impact on numerous cultural, medical, educational, and civic organizations. The engineering school at the University of California, San Diego bears Dr. and Mrs. Jacobs’ names, as do the performing arts center of the campus’ La Jolla Playhouse and the new UCSD Medical Center.
PROGRAMS & RESEARCH
The JTCII fuses academic excellence with real-world applications through its unique two-year dual master’s degree program. The first class of students will begin in the Fall of 2014. Prospective JTCII faculty members will be accomplished scientists, engineers and technologists with proven entrepreneurial skills who can effectively engage with industry.
The JTCII departs from traditional academic departments and is organized in interdisciplinary hubs selected for their relevance to the New York City economy. The three hub areas are: Connective Media, which focuses on mobile and interactive media; Healthier Life, which will create solutions for better health care outcomes; and the Built Environment, which aims to increase the efficiency and sustainability of large-scale urban environments. In addition, a dynamic Industrial Affiliates program will provide a valuable source of local experts and seasoned entrepreneurial mentors.
In Fall 2013, the JTCII will launch a Postdoctoral Innovation Fellows program to encourage entrepreneurial efforts among highly qualified scientists. The program will provide fellows with rich ties to the emerging New York City tech ecosystem, access to industrial mentors and seasoned entrepreneurs, and connections to the local venture capital and legal communities.
Founding Director, Joan and Irwin Jacobs Technion-Cornell Innovation Institute
Daniel Huttenlocher
Dean and Vice Provost, Cornell Tech
David J. Skorton
President, Cornell University
Peretz Lavie
President, Technion – Israel Institute of Technology
Board of Directors
CHAIRKent FuchsProvost, Cornell University
Arnon BenturExecutive Vice President and Director General, Technion-Israel Institute of Technology
Lance CollinsDean of the College of Engineering, Cornell University
Joanne DeStefanoVice President for Finance and Chief Financial Officer, Cornell University
Moshe EizenbergProfessor (Emeritus) of Materials Engineering and Former Vice President for Research, Technion-Israel Institute of Technology
Paul FeiginSenior Executive Vice President, Technion-Israel Institute of Technology
Daniel HuttenlocherDean and Vice Provost, Cornell Tech
Adam ShwartzChair of the Department of Electrical Engineering, Technion-Israel Institute of Technology
WHY NYC?
In 2010, the City of New York launched its groundbreaking Applied Sciences NYC program, an unparalleled opportunity to build world-class applied sciences and engineering campuses.
With Applied Sciences NYC, the city’s Economic Development Corporation seeks to dramatically expand capacity in the applied sciences to maintain global competitiveness and create jobs. By creating campuses like Cornell Tech, innovative new ideas lead to spinoff companies right here in the city that will transform its economy. The next high growth company—a Google, Amazon, or Facebook—may emerge in NYC.
ABOUT THE PARTNERS
Cornell University
Cornell University, one of the world’s powerhouse universities, is both a private university and a land grant institution of New York State, with 21,400 students in Ithaca, New York, Weill Cornell Medical College in New York City and Qatar, United Arab Emirates. An Ivy League institution, Cornell awarded the nation’s first university doctorate degrees in electrical engineering and industrial engineering. There are forty Nobel Laureates with Cornell affiliations.
Technion – Israel Institute of Technology
Technion-Israel Institute of Technology is a major source of the innovation and brainpower that drives the Israeli economy, and the cornerstone of Israel’s renown as the world’s “Start-Up Nation.” Alongside this, its three Nobel Prize Laureates exemplify traditional academic excellence. Technion people, ideas and inventions make important contributions to the world, including life-saving medicine, sustainable energy, computer software, water conservation and nanotechnology.
FIND MORE INFORMATION
Download the press release here. Visit our press kit for images.
The Technion – Israel Institute of Technology was today ranked 6th in the world by a survey conducted by MIT. The study evaluated entrepreneurship and innovation in higher education institutions worldwide. The ranking was compiled by 61 experts from 20 different countries. It identified 120 universities which demonstrate “a decisive impact and significant contribution in the field of entrepreneurship and innovation.”
Technion followed MIT, Stanford, Cambridge, Imperial College and Oxford, but preceded the University of San Diego, Berkeley, ETH Swiss and the National University of Singapore. The report also placed Israel 3rd in terms of entrepreneurship and innovation, after the US and the UK, but ahead of Sweden, Singapore, Germany, the Netherlands, China and Canada.The survey, which was carried out in partnership with the Skolkovo Institute of Science and Technology in Russia, also placed the Technion first in the category of universities that create or support technological innovation even though they operate in a challenging environment.
Instituting an institutional E&I culture – for entrepreneurship and innovation – is considered among experts as the essential ingredient for sustaining a successful system. In this respect, the Technion is mentioned as an institution that possesses the ethos of aspiration and achievement.
This is the first stage (out of three) in the comprehensive survey. In his reaction to these most favorable results, Technion President Professor Peretz Lavie said, “Technion’s position among the top ten leading universities in the world in the areas of innovation and entrepreneurship brings us closer to fulfilling our mission goals: to be counted among the top ten leading universities in the world. This is not the first time the Technion has earned international acclaim such as this,” he continued. “The university’s contribution to Israel’s advanced technology industry is recognized around the world. Not by coincidence did we prevail in the New York City’s tender last year to establish a scientific-engineering research center in partnership with Cornell University. The city’s mayor, Michael Bloomberg, said then that the Technion is the only university in the world capable of successfully turning the economic tide of an entire country, from exporters of citrus fruit to a global center for advanced industry and an authority of knowledge. To date, 61 experts from around the world have endorsed this statement.”
The Technion-Israel Institute of Technology is a major source of the innovation and brainpower that drives the Israeli economy, and a key to Israel’s reputation as the world’s “Start-Up Nation.” Its three Nobel Prize winners exemplify academic excellence.
Integration of expression data in genome-scale metabolic network reconstructions Anna S. Blazier and Jason A. Papin*
Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, USA
Front. Physiol., 06 August 2012 | http://dx.doi.org/10.3389/fphys.2012.00299
http://
The other side of cardiac Ca2+ signaling: transcriptional control Alejandro Domínguez-Rodríguez1, Gema Ruiz-Hurtado2, Jean-Pierre Benitah1 and Ana M. Gómez1*
Ca2+ is probably the most versatile signal transduction element used by all cell types. In the heart, it is essential to activate cellular contraction in each heartbeat. Nevertheless Ca2+ is not only a key element in excitation-contraction coupling (EC coupling), but it is also
a pivotal second messenger in cardiac signal transduction, being able to control processes such as
excitability, metabolism, and transcriptional regulation.
Regarding the latter, Ca2+ activates Ca2+-dependent transcription factors by a process called excitation-transcription coupling (ET coupling). ET coupling is an integrated process by which
the common signaling pathways that regulate EC coupling
activate transcription factors.
In studies on the development of cardiac hypertrophy, two Ca2+-dependent enzymes are key actors:
both of which are activated by the complex Ca2+/Calmodulin.
The question now is how ET coupling occurs in cardiomyocytes, where intracellular Ca2+ is continuously oscillating. We draw attention to location of Ca2+ signaling:
intranuclear ([Ca2+]n) or cytoplasmic ([Ca2+]c), and
the specific ionic channels involved in the activation of cardiac ET coupling.
We highlight the role of the 1,4,5 inositol triphosphate receptors (IP3Rs) in the elevation of [Ca2+]n levels, which are important to
locally activate CaMKII, and
the role of transient receptor potential channels canonical (TRPCs) in [Ca2+]c,
needed to activatecalcineurin (Cn).
Keywords: heart, calcium, excitation-transcription coupling, TRPC, nuclear calcium
Citation: Domínguez-Rodríguez A, Ruiz-Hurtado G, Benitah J-P and Gómez AM (2012) The other side of cardiac Ca2+ signaling: transcriptional control.
Front. Physio. 3:452. http://dx.doi.org/10.3389/fphys.2012.00452 Published online: 28 November 2012.
Edited by:Eric A. Sobie, Mount Sinai School of Medicine, USA; Reviewed by: Jeffrey Varner, Cornell University, USA; Ravi Radhakrishnan, University of Pennsylvania, USA
Integration of expression data in genome-scale metabolic network reconstructions Anna S. Blazier and Jason A. Papin*
Front. Physiol., 06 August 2012 | doi: 10.3389/fphys.2012.00299
With the advent of high-throughput technologies, the field of systems biology has amassed an abundance of “omics” data,
quantifying thousands of cellular components across a variety of scales,
ranging from mRNA transcript levels to metabolite quantities.
Methods are needed to not only
integrate this omics data but to also
use this data to heighten the predictive capabilities of computational models.
Several recent studies have successfully demonstrated how flux balance analysis (FBA), a constraint-based modeling approach, can be used
to integrate transcriptomic data into genome-scale metabolic network reconstructions
to generate predictive computational models.
We summarize such FBA-based methods for integrating expression data into genome-scale metabolic network reconstructions, highlighting their advantages as well as their limitations.
Introduction
Genomics provides data on a cell’s DNA sequence,
transcriptomics on the mRNA expression of cells,
proteomics on a cell’s protein composition, and
metabolomics on a cell’s metabolite abundance.
Computational methods are needed to reduce this dimensionality across the wide spectrum of omics data to improve understanding of the underlying biological processes (Cakir et al., 2006; Pfau et al., 2011).
Metabolic network reconstructions are an advantageous platform for the integration of omics data (Palsson, 2002). Assembled in part from
annotated genomes as well as
biochemical, genetic, and cell phenotype data,
a metabolic network reconstruction is a manually-curated, computational framework that
enables the description of gene-protein-reaction relationships (Chavali et al., 2012).
After applying constraints, the solution space of possible phenotypes narrows, allowing for more accurate characterization of the reconstructed metabolic network,
Omics data can be used to further constrain the possible solution space and
Given the wealth of transcriptomic data, efforts to integrate mRNA expression data with metabolic network reconstructions, have, in particular, made significant progress when using FBA as an analytical platform (Covert and Palsson, 2002; Akesson et al., 2004; Covert et al., 2004). However, despite this abundance of data, the integration of expression data faces unique challenges such as
experimental and inherent biological noise,
variation among experimental platforms,
detection bias, and the
unclear relationship between gene expression and reaction flux
The past few years have witnessed several advances in the integration of transcriptomic data with genome-scale metabolic network reconstructions. Specifically, numerous FBA-driven algorithms have been introduced that use experimentally derived mRNA transcript levels to modify the network’s reactions either by
inactivating them entirely or
by constraining their activity levels.
Such algorithms have demonstrated their applicability by, for example,
classifying tissue-specific metabolic activity in the human network and
by identifying novel drug targets in Mycobacterium tuberculosis
We summarize various FBA-driven methods for integrating expression data into genome-scale metabolic network reconstructions.
We survey the limitations of these algorithms as well as look to the future of
multi-omics data integration using genome-scale metabolic network reconstructions as the scaffold.
Flux balance analysis
FBA is a constraint-based modeling approach that characterizes and predicts aspects of an organism’s metabolism (Gianchandani et al., 2009) To use FBA, the user supplies a metabolic network reconstruction in the form of a stoichiometric matrix, S, where
the rows in S correspond to the metabolites of the reconstruction and
the columns in S represent reactions in the reconstruction.
a stoichiometric coefficient sij conveys the molecularity of a certain metabolite in a particular reaction, with
sij ≥ 1 indicating that the metabolite is a product of the reaction,
sij ≤ −1 a reactant, and
sij = 0 signifies that the metabolite is not involved.
A system of linear equations is established by multiplying the S matrix by a column vector, v, which contains the unknown fluxes through each of the reactions of the S matrix. Under the assumption that the system operates at steady-state, that is to say there is no net production or consumption of mass within the system, the product of this matrix multiplication must equal zero, S · v = 0 (Gianchandani et al., 2009). Because the resulting system is underdetermined (i.e., too few equations, too many unknowns), linear programming (LP) is used to optimize for a particular flux,Z, the objective function, subject to underlying constraints. The objective function typically takes on the form of: Z = c ⋅ v
where c is a row vector of weights for each of the fluxes in column vector v, indicating how much each reaction in v contributes to the objective function,Z (Lee et al., 2006; Orth et al., 2010). Examples of objective functions include maximizing biomass, ATP production, and the production of a metabolite of interest (Lewis et al., 2012).
(1)
subject to
S ⋅ v = 0
(2)
lb ≤ v ≤ ub
(3)
(1) outlines the objective function to be optimized,
(2) the steady state assumption, and
(3) describes the upper and lower bounds, ub and lb, of each of the fluxes in v according to such constraints as
Through this application of constraints, the solution space of physiologically feasible flux distributions for v shrinks. Thus, the task of FBA is to find a solution to v that lies within the bounded solution space and that optimizes the objective function at the same time.
Several recently developed algorithms have demonstrated how expression data can be incorporated into FBA models to further constrain the flux distribution solution space in genome-scale metabolic network reconstructions . Summary of the algorithms for the integration of expression data. Table 1 image URL http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3429070/table/T1/?report=thumb
List of Methods:
GIMME guarantees to both produce a functioning metabolic model based on gene expression levels and quantify the agreement between the model and the data is called the Gene Inactivity Moderated by Metabolism and Expression (GIMME) algorithm (Becker and Palsson, 2008).
iMAT Similar to GIMME, the Integrative Metabolic Analysis Tool (iMAT) results in a functioning model in which the fluxes of reactions correlated with high mRNA levels are maximized and the fluxes of reactions associated with low mRNA levels are minimized (Shlomi et al., 2008; Zur et al., 2010). A key difference is that iMAT does not require a priori knowledge of a defined metabolic functionality. Briefly, this method establishes a tri-valued gene-to-reaction mapping for each reaction in the model according to the level of gene expression in the data. iMAT requires that reactions catalyzed by the products of highly expressed genes are able to carry a minimum flux. By removing this need for user-specified objective functions, iMAT bypasses assumptions about metabolic functionalities of a particular network, which proves advantageous for models where there is no clear objective function, as in models of mammalian cells.
MADE While both GIMME and iMAT rely on user-specified threshold values to determine which reactions are highly expressed and which reactions are lowly expressed, Metabolic Adjustment by Differential Expression (MADE) uses statistically significant changes in gene expression measurements to determine sequences of highly and lowly expressed reactions (Jensen and Papin, 2011). The lack of correlation between mRNA levels and protein levels makes it difficult to accurately determine when genes are “turned on,” and when they are “turned off.” Therefore, in eliminating this need for thresholding, MADE removes significant user-bias from the system.
E-Flux Whereas GIMME, iMAT, and MADE incorporate gene expression data into their models by reducing gene expression levels to binary states, the method E-Flux attempts to more directly incorporate gene expression data into FBA optimization problems by constraining the maximum possible flux through the reactions (Colijn et al., 2009). Rather than setting the upper bounds of a reaction to some large constant or 0, mirroring the implementation of binary-based algorithms, E-Flux constrains the upper bound of a reaction according to its respective gene expression level relative to a particular threshold. In cases where the gene expression data is below a certain threshold, tight constraints are placed on the flux through the corresponding reactions in the reconstruction; conversely, in cases where the gene expression is above a certain threshold, loose constraints are placed on the flux through the corresponding reactions.
PROM In contrast to the other methods discussed, which focused solely on integrating gene expression data into genome-scale metabolic network reconstructions, Probabilistic Regulation of Metabolism (PROM) aims to fuse together metabolic networks and transcription regulatory networks with expression data (Chandrasekaran and Price, 2010). To run PROM, the user supplies a genome-scale metabolic network reconstruction, a regulatory network structure describing transcription factors and their targets, and a range of expression data from various environmental and genetic perturbations. Given this expression data, PROM binarizes the genes with respect to a user-supplied threshold to evaluate the likelihood of the expression of a target gene given the expression of that gene’s transcription factor.
Challenges facing the integration of expression data
Each of the methods discussed hinges on the assumption that mRNA transcript levels are a strong indicator for the level of protein activity. For instance, GIMME and iMAT assume that mRNA levels below a certain threshold suggest that the corresponding reactions are inactive. MADE follows a similar logic, turning reactions on and off depending on the changes in mRNA transcript levels. E-Flux and PROM assume that transcript levels indicate the degree to which reactions are active, evident in the constraining of the upper bounds in the FBA optimization problems associated with these methods.
Rather than requiring that the reconstruction mirror the expression data exactly, the methods allow for deviations in the FBA flux solution space in order to generate a functioning model that adheres to the specified constraints. In the case of GIMME, highly expressed reactions are prioritized relative to lowly expressed reactions; however, in the event that an optimal, functioning solution cannot be found, the assumption can be violated and lowly expressed reactions can be added back into the reconstruction. Thus, this assumption that mRNA transcript levels correlate to protein levels serves as a cue rather than a mandate.
Conclusion
The above methods have been used to not only integrate expression data from a variety of sources but to also make progress toward overcoming key challenges in the field of systems biology. For instance, iMAT, highlighting its applicability in multi-cellular organisms, was used to curate the human metabolic network reconstruction and predict tissue-specific gene activity levels in ten human tissues (Duarte et al., 2007; Shlomi et al., 2008). Additionally, both E-Flux and PROM have been used to discover novel drug targets in Mycobacterium tuberculosis (Colijn et al., 2009; Chandrasekaran and Price, 2010).
Given the recent success with using genome-scale metabolic network reconstructions as a platform for integrating expression data, efforts should focus on multi-omics data integration. A handful of methods have already been introduced that integrate two or more types of omics data into genome-scale metabolic network reconstructions. For example, despite the current dearth of quantitative metabolomics data, a method has been developed that demonstrates how semi-quantitative metabolomics data can be used with transcriptomic data to curate genome-scale metabolic network reconstructions and identify key reactions involved in the production of certain metabolites (Cakir et al., 2006). Another algorithm, called Integrative Omics-Metabolic Analysis (IOMA), integrates metabolomics data and proteomics data into a genome-scale metabolic network reconstruction by evaluating kinetic rate equations subject to quantitative omics measurements (Yizhak et al., 2010). Furthermore, Mass Action Stoichiometric Simulation (MASS) uses metabolomic, fluxomic, and proteomic data to transform a static stoichiometric reconstruction of an organism into a large-scale dynamic network model (Jamshidi and Palsson, 2010). And finally, building off of iMAT, the Model-Building Algorithm (MBA) utilizes literature-based knowledge, transcriptomic, proteomic, metabolomic, and phenotypic data to curate the human metabolic network reconstruction to derive a more complete picture of tissue-specific metabolism (Jerby et al., 2010). Such algorithms show promise in their ability to easily integrate high-throughput data into genome-scale metabolic network reconstructions to generate phenotypically accurate and predictive computational models.
Chefs and Restaurant Operators Recognized at Culinary Institute of America-Greystone for “Seductive Nutrition” Approach to Making Popular Dishes a Bit Healthier
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Unilever Food Solutions and Renowned Food Psychologist Dr. Brian Wansink Share How Restaurant Chefs and Home Cooks Alike Can Adopt the Same Approach
LISLE, Ill., Nov. 12, 2012 /PRNewswire/ — This past weekend, Unilever Food Solutions hosted a select group of chefs and restaurant operators at the Culinary Institute of America-Greystone (CIA) to highlight their efforts to help people choose delicious, slightly healthier meals when they eat out through a new concept called “Seductive Nutrition.” Developed by Unilever Food Solutions after the release of a global World Menu Report, “Seductive Nutrition” nudges guests to choose top menu items made slightly healthier through small changes to ingredients and preparation methods, with more enticing menu descriptions.
Several of the chefs and operators in attendance were awarded the CIA weekend trip as winners in Unilever Food Solutions’ “Seductive Nutrition Challenge.” The challenge asked restaurants to pledge to cut 100 calories from a top menu item by applying “Seductive Nutrition” tools and techniques. The CIA event served as a national stage for them to share their success story among their industry peers and experts in the field, as well as motivate additional chefs to adopt the same approach to help Americans everywhere eat a little healthier when dining out, without sacrificing enjoyment.
“Unilever Food Solutions’ ‘Seductive Nutrition’ approach aligns with existing research that shows the dining choices we make can easily be shaped by minor cues, like changing the name of grilled chicken to Savory Southwestern Grilled Chicken,” said Brian Wansink, PhD, director of the Food and Brand Lab at Cornell University and author ofMindless Eating: Why We Eat More Than We Think. “The chefs showed that you can even reduce calories in popular dishes and still make them very appealing.” Dr. Wansink led a talk at the CIA event focused on “Mindless Eating” and how the wording of food descriptions and how the way food is presented can help entice diners into eating more healthfully.
“We’re thrilled to see the concept of ‘Seductive Nutrition’ put into practice at restaurants, college campuses and other out-of-home dining venues,” said Lisa Carlson, MS, RD, nutrition manager at Unilever Food Solutions. “The winning chefs have truly captured the essence of Seductive Nutrition – shaving a small number of calories, while making their dish just as delicious and appealing by romancing the menu descriptions.”
From an independent restaurant to a retirement community, the “Seductive Nutrition” Challenge winners represented a variety of restaurant segments:
Keith Esbin, of Bar Harbor Seafood Corporation and Boston Lobster Feast Restaurants in Orlando, Florida, switched up his New England Lobster Roll Platter using light mayonnaise and additional herbs and seasonings to become a Less Guilty New England Lobster Roll Platter. Esbin’s menu change allowed his business to reach a new customer base who looked at them as being more socially, environmentally and nutritionally responsible.
Thomas Ryan, of Resurrection Retirement Community in Chicago, changed his popular restaurant dish of Swedish Meatballs to Chicken Swedish Meatballs. He also revised the menu description to “tender chicken meatballs in creamy mushroom sauce” to make the dish sound much more enticing.
The two winners demonstrated their menu item changes during their trip to the Culinary Institute of America-Greystone. They participated in a hands-on session where they showed customers the small changes they had made to reduce calories. In addition, they received a tour of the Culinary Institute, learned additional healthy cooking techniques from chefs and attended a “Healthy Inspiration” lunch and wine tasting.
While the Culinary Institute of America-Greystone event focused on restaurant chefs and operators, the tips shared by Dr. Wansink can translate from out-of-home to in-home dining. For instance:
Simple, yet descriptive, words can help guests choose healthier menu items. Including descriptive adjectives can turn everyday mashed potatoes into “creamy, whipped mashed potatoes,” and a yogurt parfait into a “silken yogurt parfait.”
Incorporating vivid adjectives can trigger people’s meal expectations. Wansink and his team’s analysis of more than 1,000 descriptively named menu items pointed to three key ways for foods to be “seductively” named:
Geographic labels – Using words to create an image or illicit the ideology of a geographic area that consumers can associate with foods; e.g., Southwestern Tex-Mex Salad.
Nostalgic labels – Alluding to a diner’s past can trigger happy associations tied to family, tradition, national origin and a sense of wholesomeness. Use fond associations to create appealing names; e.g., Old-World Italian Manicotti.
Sensory labels – Describing the taste, smell and texture of menu items served can help set consumers’ dining expectations; e.g., Warm Apple Crisp.
“Seductive Nutrition” includes the holistic dining experience. Nice dinnerware, soft light and a matching tablecloth can help enhance a person’s dining expectations. Wansink’s research also found people rated the taste of a brownie much higher when served on a nice dinner plate than on a cheap plastic plate.
For more information on Unilever Food Solutions, the “Seductive Nutrition” approach to menu development and the “Seductive Nutrition” Challenge, please visit www.unileverfoodsolutions.us.
About Unilever Food Solutions North America
At Unilever Food Solutions, we help chefs all over the world serve tasty, wholesome meals that keep guests coming back for more. We create ingredients that save precious prep time in the kitchen without compromising on flavor or flair, and constantly provide ideas and inspiration that keep your menu fresh and exciting. Our ingredients are some of the staples of professional kitchens in 74 countries around the world: Knorr, Hellmann’s, Lipton and more. We’ve been in the foodservice industry since the 1880s. We have more than 300 chefs on staff around the world. We understand that critical balance between impressing your guests and making a profit, and how to keep your menus and recipes fresh and exciting as times and tastes change.
For More Information:
Anne O’Reilly
GolinHarris Public Relations
+1 (312) 729-4060 aoreilly@golinharris.com
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