Advertisements
Feeds:
Posts
Comments

Posts Tagged ‘Suresh K. Niture’


Sensors and Signaling in Oxidative Stress

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

This is article ELEVEN in the following series on Calcium Role in Cardiovascular Diseases

Part I: Identification of Biomarkers that are Related to the Actin Cytoskeleton
Larry H Bernstein, MD, FCAP
https://pharmaceuticalintelligence.com/2012/12/10/identification-of-biomarkers-
that-are-related-to-the-actin-cytoskeleton/

Part II: Role of Calcium, the Actin Skeleton, and Lipid Structures in Signaling and Cell Motility
Larry H. Bernstein, MD, FCAP, Stephen Williams, PhD and Aviva Lev-Ari, PhD, RN
https://pharmaceuticalintelligence.com/2013/08/26/role-of-calcium-the-actin-
skeleton-and-lipid-structures-in-signaling-and-cell-motility/

Part III: Renal Distal Tubular Ca2+ Exchange Mechanism in Health and Disease
Larry H. Bernstein, MD, FCAP, Stephen J. Williams, PhD
and Aviva Lev-Ari, PhD, RN
https://pharmaceuticalintelligence.com/2013/09/02/renal-distal-tubular-ca2-
exchange-mechanism-in-health-and-disease/

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

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

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

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

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
Aviva Lev-Ari, PhD, RN
https://pharmaceuticalintelligence.com/2013/08/01/calcium-molecule-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/

Part VII: Cardiac Contractility & Myocardium Performance: Ventricular Arrhythmias and Non-ischemic Heart Failure –
Therapeutic Implications for Cardiomyocyte Ryanopathy (Calcium Release-related Contractile Dysfunction) and Catecholamine Responses
Justin Pearlman, MD, PhD, FACC, Larry H Bernstein, MD, FCAP and Aviva Lev-Ari, PhD, RN
https://pharmaceuticalintelligence.com/2013/08/28/cardiac-contractility-myocardium-performance-ventricular-arrhythmias-
and-non-ischemic-heart-failure-therapeutic-implications-for-cardiomyocyte-ryanopathy-calcium-release-related-contractile/

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

Part IX: Calcium-Channel Blockers, Calcium Release-related Contractile Dysfunction
(Ryanopathy) and Calcium as Neurotransmitter Sensor
Justin Pearlman, MD, PhD, FACC, Larry H Bernstein, MD, FCAP and Aviva Lev-Ari, PhD, RN
https://pharmaceuticalintelligence.com/2013/09/16/calcium-channel-blocker-calcium-as-neurotransmitter-sensor-
and-calcium-release-related-contractile-dysfunction-ryanopathy/

Part X: Synaptotagmin functions as a Calcium Sensor: How Calcium Ions Regulate the fusion of
vesicles with cell membranes during Neurotransmission
Larry H Bernstein, MD, FCAP and Aviva Lev-Ari, PhD, RN
https://pharmaceuticalintelligence.com/2013/09/10/synaptotagmin-functions-as-a-calcium-sensor-how-calcium-ions-
regulate-the-fusion-of-vesicles-with-cell-membranes-during-neurotransmission/

Part XI: Sensors and Signaling in Oxidative Stress
Larry H. Bernstein, MD, FCAP
https://pharmaceuticalintelligence.com/2013/11/01/sensors-and-signaling-in-oxidative-stress/

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

https://pharmaceuticalintelligence.com/2013/12/21/genetic-polymorphisms-of-ion-channels-have-a-role-in-the-pathogenesis-of-coronary-microvascular-dysfunction-and-ischemic-heart-disease/

This important article on oxidative stress was published in Free Radical Biol. and Med.

Nrf2:INrf2(Keap1) Signaling in Oxidative Stress

James W. Kaspar, Suresh K. Niture, and Anil K. Jaiswal*
Department of Pharmacology, University of Maryland School of Medicine, Baltimore, MD

Free Radic Biol Med. 2009 Nov; 47(9): 1304–1309.           http://dx.doi.org/10.1016/j.freeradbiomed.2009.07.035

Nrf2:INrf2(Keap1) are cellular sensors of chemical and radiation induced oxidative and electrophilic stress. Nrf2 is a nuclear transcription factor that controls the expression and coordinated induction of a battery of defensive genes encoding detoxifying enzymes and antioxidant proteins. This is a mechanism of critical importance for cellular protection and cell survival. Nrf2 is retained in the cytoplasm by an inhibitor INrf2. INrf2 functions as an adapter for Cul3/Rbx1 mediated degradation of Nrf2. In response to oxidative/electrophilic stress, Nrf2 is switched on and then off by distinct early and delayed mechanisms. Oxidative/electrophilic modification of INrf2cysteine151 and/or PKC phosphorylation of Nrf2serine40 results in

  • the escape or release of Nrf2 from INrf2.

Nrf2 is stabilized and

  • translocates to the nucleus,
  • forms heterodimers with unknown proteins, and
  • binds antioxidant response element (ARE) that
  • leads to coordinated activation of gene expression.
  • It takes less than fifteen minutes from the time of exposure to switch on nuclear import of Nrf2. This is followed by activation of a delayed mechanism that controls switching off of Nrf2 activation of gene expression. GSK3β phosphorylates Fyn at unknown threonine residue(s) leading to nuclear localization of Fyn. Fyn phosphorylates Nrf2tyrosine568
  • resulting in nuclear export of Nrf2, binding with INrf2 and
  • degradation of Nrf2.

The switching on and off of Nrf2 protects cells against free radical damage, prevents apoptosis and promotes cell survival.

Introduction

Oxidative stress is induced by a vast range of factors including xenobiotics, drugs, heavy metals and ionizing radiation. Oxidative stress leads to the generation of Reactive Oxygen Species (ROS) and electrophiles. ROS and electrophiles generated can have a profound impact on survival, growth development and evolution of all living organisms [1,2] ROS include

  • both free radicals, such as the superoxide anion and the hydroxyl radical, and
  • oxidants such as hydrogen peroxide [3].

ROS and electrophiles can cause diseases such as cancer, cardiovascular complications, acute and chronic inflammation, and neurodegenerative diseases [1]. Therefore, it is obvious that

  • cells must constantly labor to control levels of ROS, preventing them from accumulation.

Much of what we know about the mechanisms of protection against oxidative stress has come from the study of prokaryotic cells [4,5]. Prokaryotic cells utilize transcription factors OxyR and SoxRS to sense the redox state of the cell, and

  • during oxidative stress these factors induce the expression of nearly eighty defensive genes [5].

Eukaryotic cells have similar mechanisms to protect against oxidative stress [Fig. 1; ref. 3,6–9]. Initial effect of oxidative/electrophilic stress leads to activation of a battery of defensive gene expression that leads to detoxification of chemicals and ROS and prevention of free radical generation and cell survival [Fig. 1].

Fig 1.  Chemical and radiation exposure and coordinated induction of defensive genes.

Fig. 1. Chemical and radiation exposure and coordinated induction of defensive genes.

Of these genes, some are enzymes such as NAD(P)H:quinine oxidoreductase 1 (NQO1), NRH:quinone oxidoreductase 2 (NQO2), glutathione S-transferase Ya subunit (GST Ya Subunit), heme oxygenase 1 (HO-1), and γ-glutamylcysteine synthetase (γ-GCS), also known as glutamate cysteine ligase (GCL). Other genes have end products that regulate a wide variety of cellular activities including

  • signal transduction,
  • proliferation, and
  • immunologic defense reactions.

There is a wide variety of factors associated with the cellular response to oxidative stress. For example,

  • NF-E2 related factor 2 (Nrf2),
  • heat shock response activator protein 1, and
  • NF-kappaB promote cell survival,

whereas activation of c-jun, N-terminal kinases (JNK), p38 kinase and TP53 may lead to cell cycle arrest and apoptosis [10]. The Nrf2 pathway is regarded as the most important in the cell to protect against oxidative stress. [3,6–9]. It is noteworthy that accumulation of ROS and/or electrophiles leads to oxidative/electrophile stress,

  • membrane damage,
  • DNA adducts formation and
  • mutagenicity [Fig. 1].

These changes lead to degeneration of tissues and premature aging, apoptotic cell death, cellular transformation and cancer.

Antioxidant Response Element and Nrf2

Promoter analysis identified a cis-acting enhancer sequence designated as the antioxidant response element (ARE) that

  • controls the basal and inducible expression of antioxidant genes in response to xenobiotics, antioxidants, heavy metals and UV light [11].

The ARE sequence is responsive to a broad range of structurally diverse chemicals apart from β-nafthoflavone and phenolic antioxidants [12]. Mutational analysis revealed GTGACA***GC to be the core sequence of the ARE [11,13–14]. This core sequence is present in all Nrf2 downstream genes that respond to antioxidants and xenobiotics [3,6–9]. Nrf2 binds to the ARE and regulates ARE-mediated antioxidant enzyme genes expression and induction in response to a variety of stimuli including antioxidants, xenobiotics, metals, and UV irradiation [6,15–21].

Nrf2 is ubiquitously expressed in a wide range of tissue and cell types [22–24] and belongs to a subset of basic leucine zipper genes (bZIP) sharing a conserved structural domain designated as a cap’n’collar domain which is highly conserved in Drosphila transcription factor CNC (Fig. 2; ref. 25].

Fig. 2. Schematic Presentation of Various Domains of Nrf (Nrf1, Nrf2, Nrf3) and INrf2

Fig. 2. Schematic Presentation of Various Domains of Nrf (Nrf1, Nrf2, Nrf3) and INrf2

Nrf, NF-E2 Related Factor; INrf2, Inhibitor of Nrf2; NTR, N-Terminal Region; BTB, Broad complex, Tramtrack, Bric-a-brac; IVR, Intervening/linker Region; DGR, Kelch domain/ diglycine repeats; CTR, C-Terminal Region.

The basic region, just upstream of the leucine zipper region,

  • is responsible for DNA binding [3] and
  • the acidic region is required for transcriptional activation.

ARE-mediated transcriptional activation requires heterodimerization of Nrf2 with other bZIP proteins including Jun (c-Jun, Jun-D, and Jun-B) and small Maf (MafG, MafK, MafF) proteins [18– 20,26–27].

Initial evidence demonstrating the role of Nrf2 in antioxidant-induction of detoxifying enzymes came from studies on

  • the role of Nrf2 in ARE-mediated regulation of NQO1 gene expression [17].

Nrf2 was subsequently shown to be involved in

  • the transcriptional activation of other ARE-responsive genes such as
    • GST Ya, γ-GCS, HO-1, antioxidants, proteasomes, and drug transporters [3,6–9,28–33].

Overexpression of Nrf2 cDNA was shown to upregulate the expression and induction of the NQO1 gene in response to antioxidants and xenobiotics [17]. In addition, Nrf2-null mice exhibited a marked

  • decrease in the expression and induction of NQO1,
  • indicating that Nrf2 plays an essential role in the in vivo regulation of NQO1 in response to oxidative stress [26].

The importance of this transcription factor in upregulating ARE-mediated gene expression has been demonstrated by several in vivo and in vitro studies [reviewed in ref. 3]. The results indicate that Nrf2 is an important activator of phase II antioxidant genes [3,8].

Negative Regulation of Nrf2 mediated by INrf2

A cytosolic inhibitor (INrf2), also known as Keap1 (Kelch-like ECH-associating protein 1), of Nrf2 was identified and reported [Fig. 2; ref. 34–35]. INrf2, existing as a dimer [36], retains Nrf2 in the cytoplasm. Analysis of the INrf2 amino acid sequence and domain structure-function analyses have revealed that

  • INrf2 has a BTB (broad complex, tramtrack, bric-a-brac)/ POZ (poxvirus, zinc finger) domain and
  • a Kelch domain [34–35] also known as the DGR domain (Double glycine repeat) [37].

Keap1 has three additional domains/regions:

  1. the N-terminal region (NTR),
  2. the invervening region (IVR), and
  3. the C-terminal region (CTR) [8].

The BTB/POZ domain has been shown to be

  • a protein-protein interaction domain.

In the Drosophila Kelch protein, and in IPP,

  • the Kelch domain binds to actin [38–39]
  • allowing the scaffolding of INrf2 to the actin cytoskeleton
    • which plays an important role in Nrf2 retention in the cytosol [40].

The main function of INrf2 is to serve as

  • an adapter for the Cullin3/Ring Box 1 (Cul3/Rbx1) E3 ubiquitin ligase complex [41–43].

Cul3 serves as a scaffold protein that forms the E3 ligase complex with Rbx1 and recruits a cognate E2 enzyme [8].

INrf2

  1. via its N-terminal BTB/POZ domain binds to Cul3 [44] and
  2. via its C-terminal Kelch domain binds to the substrate Nrf2
  • leading to the ubiquitination and degradation of Nrf2 through the 26S proteasome [45–49].

Under normal cellular conditions, the cytosolic INrf2/Cul3-Rbx1 complex is constantly degrading Nrf2. When a cell is exposed to oxidative stress Nrf2 dissociates from the INrf2 complex, stabilizes and translocates into the nucleus leading to activation of ARE-mediated gene expression [3,6–9]. An alternative theory is that Nrf2 in response to oxidative stress escapes INrf2 degradation, stabilizes and translocates in the nucleus [49–50]. We suggested the theory of escape of Nrf2 from INrf2 [49] and similar suggestion was also made in another report [50]. However, the follow up studies in our laboratory could not support the escape theory. Escape theory is a possibility but has to be proven by experiments before it can be adapted. Therefore, we will use the release of Nrf2 from INrf2 in the rest of this review.

Numerous reports have suggested that

  • any mechanism that modifies INrf2 and/or Nrf2 disrupting the Nrf2:INrf2 interaction will result in the upregulation of ARE-mediated gene expression.

A model Nrf2:INrf2 signaling from antioxidant and xenobiotic to activation of ARE-mediated defensive gene expression is shown in Fig. 3.

Fig. 3. Nrf2 signaling in ARE-mediated coordinated activation of defensive genes

Fig. 3. Nrf2 signaling in ARE-mediated coordinated activation of defensive genes

Since the metabolism of antioxidants and xenobiotics results in the generation of ROS and electrophiles [51], it is thought that these molecules might act as second messengers, activating ARE-mediated gene expression. Several protein kinases including PKC, ERK, MAPK, p38, and PERK [49,52– 56] are known to modify Nrf2 and activate its release from INrf2. Among these mechanisms,

  1. oxidative/electrophilic stress mediated phosphorylation of Nrf2 at serine40 by PKC is necessary for Nrf2 release from INrf2, but
  2. is not required for Nrf2 accumulation in the nucleus [49,52–53].

In addition to post-translational modification in Nrf2, several crucial residues in INrf2 have also been proposed to be important for activation of Nrf2. Studies based on

  • the electrophile mediated modification,
  • location and
  • mutational analyses revealed
    • that three cysteine residues, Cys151, Cys273 and Cys288 are crucial for INrf2 activity [50].

INrf2 itself undergoes ubiquitination by the Cul3 complex, via a proteasomal independent pathway,

  • which was markedly increased in response to phase II inducers such as antioxidants [57].

It has been suggested that normally INrf2 targets Nrf2 for ubiquitin mediated degradation but

  • electrophiles may trigger a switch of Cul3 dependent ubiquitination from Nrf2 to INrf2 resulting in ARE gene induction.

The redox modulation of cysteines in INrf2

  • might be a mechanism redundant to the phosphorylation of Nrf2 by PKC, or that
  • the two mechanisms work in concert.

In addition to cysteine151 modification,

  • phosphorylation of Nrf2 has also been shown to play a role in INrf2 retention and release of Nrf2.

Serine104 of INrf2 is required for dimerization of INrf2, and

  • mutations of serine104 led to the disruption of the INrf2 dimer leading to the release of Nrf2 [36].

Recently, Eggler at al. demonstrated that modifying specific cysteines of the electrophile-sensing human INrf2 protein is insufficient to disrupt binding to the Nrf2 domain Neh2 (58). Upon introduction of electrophiles, modification of INrf2C151 leads to a change in the conformation of the BTB domain by means of perturbing the homodimerization site, disrupting Neh2 ubiquitination, and causing ubiquitination of INrf2. Modification of INrf2 cysteines by electrophiles does not lead to disruption of the INrf2–Nrf2 complex. Rather, the switch of ubiquitination from Nrf2 to INrf2 leads to Nrf2 nuclear accumulation.

More recently, our laboratory demonstrated that phosphorylation and de-phosphorylation of tyrosine141 in INrf2 regulates its stability and degradation, respectively [59]. The de-phosphorylation of tyrosine141 caused destabilization and degradation of INrf2 leading to the release of Nrf2. Furthermore, we showed that prothymosin-α mediates nuclear import of the INrf2/Cul3-Rbx1 complex [60]. The INrf2/Cul3-Rbx1 complex inside the nucleus exchanges prothymosin-α with Nrf2 resulting in degradation of Nrf2. These results led to the conclusion that prothymosin-α mediated nuclear import of INrf2/Cul3-Rbx1 complex leads to ubiquitination and degradation of nuclear Nrf2 presumably to regulate nuclear level of Nrf2 and rapidly switch off the activation of Nrf2 downstream gene expression. An auto-regulatory loop also exists within the Nrf2 pathway [61]. An ARE was identified in the INrf2 promoter that facilitates Nrf2 binding causing induction of the INrf2 gene. Nrf2 regulates INrf2 by controlling its transcription, and INrf2 controls Nrf2 by serving as an adaptor for degradation.

Other Regulatory Mediators of Nrf2

Bach1 (BTB and CNC homology 1, basic leucine zipper transcription factor 1) is a transcription repressor [62] that is ubiquitously expressed in tissues [63–64] and distantly related to Nrf2 [8]. In the absence of cellular stress, Bach1 heterodimers with small Maf proteins [65] that bind to the (ARE) [66] repressing gene expression. In the presence of oxidative stress, Bach1 releases from the ARE and is replaced by Nrf2. Bach1 competes with Nrf2 for binding to the ARE leading to suppression of Nrf2 downstream genes [66].

Nuclear import of Nrf2, from time of exposure to stabilization, takes roughly two hours [67]. This is followed by activation of a delayed mechanism involving Glycogen synthase kinase 3 beta (GSK3f3) that controls switching off of Nrf2 activation of gene expression (Fig. 3). GSK3f3 is a multifunctional serine/threonine kinase, which plays a major role in various signaling pathways [68]. GSK3f3 phosphorylates Fyn, a tyrosine kinase, at unknown threonine residue(s) leading to nuclear localization of Fyn [69]. Fyn phosphorylates Nrf2 tyrosine 568 resulting in nuclear export of Nrf2, binding with INrf2 and degradation of Nrf2 [70].

The negative regulation of Nrf2 by Bach1 and GSK3f3/Fyn are important in repressing Nrf2 downstream genes that were induced in response to oxidative/electrophilic stress. The tight control of Nrf2 is vital for the cells against free radical damage, prevention of apoptosis and cell survival [3,6–9,70].

Nrf2 in Cytoprotection, Cancer and Drug Resistance

Nrf2 is a major protective mechanism against xenobiotics capable of damaging DNA and initiating carcinogenesis [71]. Inducers of Nrf2 function as blocking agents that prevents carcinogens from reaching target sites, inhibits parent molecules undergoing metabolic activation, or subsequently preventing carcinogenic species from interacting with crucial cellular macromolecules, such as DNA, RNA, and proteins [72]. A plausible mechanism by which blocking agents impart their chemopreventive activity is the induction of detoxification and antioxidant enzymes [73]. Oltipraz, 3H-1,2,-dithiole-3-thione (D3T), Sulforaphane, and Curcumin can be considered potential chemopreventive agents because

  • these compounds have all been shown to induce Nrf2 [74–81].

Studies have shown a role of Nrf2 in protection against cadmium and manganese toxicity [82]. Nrf2 also plays an important role in reduction of methyl mercury toxicity [83]. Methylmercury activates Nrf2 and the activation of Nrf2 is essential for reduction of methylmercury by facilitating its excretion into extracellular space. In vitro and in vivo studies have shown a role of Nrf2 in neuroprotection and protection against Parkinson’s disease [84– 86]. Disruption of Nrf2 impairs the resolution of hyperoxia-induced acute lung injury and inflammation in mice [87]. Nrf2-knockout mice were more prone to

  • tumor growth when exposed to carcinogens such as benzo[a]pyrene, diesel exhaust, and N-nitrosobutyl (4-hydroxybutyl) amine [88–90].

INrf2/Nrf2 signaling is also shown to regulate oxidative stress tolerance and lifespan in Drosophila [91].

A role of Nrf2 in drug resistance is suggested based on its property to induce detoxifying and antioxidant enzymes (92–97). The loss of INrf2 (Keap1) function is shown to

  • lead to nuclear accumulation of Nrf2, activation of metabolizing enzymes and drug resistance (95).

Studies have reported mutations resulting in dysfunctional INrf2 in lung, breast and bladder cancers (96–100). A recent study reported that somatic mutations also occur in the coding region of Nrf2, especially in cancer patients with a history of smoking or suffering from squamous cell carcinoma (101). These mutations abrogate its interaction with INrf2 and nuclear accumulation of Nrf2. This gives advantage to

  • cancer cell survival and
  • undue protection from anti-cancer treatments.

However, the understanding of the mechanism of Nrf2 induced drug resistance remains in its infancy. In addition, the studies on Nrf2 regulated downstream pathways that contribute to drug resistance remain limited.

Future Perspectives

Nrf2 creates a new paradigm in cytoprotection, cancer prevention and drug resistance. Considerable progress has been made to better understand all mechanisms involved within the intracellular pathways regulating Nrf2 and its downstream genes. Preliminary studies demonstrate that

  • deactivation of Nrf2 is as important as activation of Nrf2.

Further studies are needed to better understand the negative regulation of Nrf2. Also better understanding of the negative regulation of Nrf2 could help design a new class of effective chemopreventive compounds not only targeting Nrf2 activation, but also

  • targeting the negative regulators of Nrf2.

Abbreviations: 

Nrf2    NF-E2 related factor 2;  INrf2   Inhibitor of Nrf2 also known as Keap1;   ROS    Reactive oxygen species.

References (1-15 of 101)

1. Breimer LH. Molecular Mechanisms of oxygen radical carcinogenesis and mutagenesis: the role of DNA base damage. Mol Carcinog 1990;3:188–197. [PubMed: 2206282]

2. Meneghini R. Iron homeostasis, oxidative stress, and DNA damage. Free Radic Biol Med 1997;23:783– 792. [PubMed: 9296456]

3. Jaiswal AK. Nrf2 signaling in coordinated activation of antioxidant gene expression. Free Radic Biol Med 2004;36:1199–1207. [PubMed: 15110384]

4. Bauer CE, Elsen S, Bird TH. Mechanisms for redox control of gene expression. Annu Rev Microbiol 1999;53:495–523. [PubMed: 10547699]

5. Zheng M, Storz G. Redox sensing by prokaryotic transcription factors. Biochem Pharm 2000;59:1–6. [PubMed: 10605928]

6. Dhakshinamoorthy S, Long DJ II, Jaiswal AK. Antioxidant regulation of genes encoding enzymes that detoxify xenobiotics and carcinogens. Current Topics in Cellular Regulation 2000;36:201–206. [PubMed: 10842753]

7. Zhang DD. Mechanistic studies of the Nrf2-Keap1 signaling pathway. Drug Metab Rev 2006;38:769– 789. [PubMed: 17145701]

8. Kobayashi M, Yamamoto M. Nrf2-Keap1 regulation of cellular defense mechanisms against electrophiles and reactive oxygen species. Adv Enzyme Regul 2006;46:113–140. [PubMed: 16887173]

9. Copple IM, Goldring CE, Kitteringham NR, Park BK. The Nrf2-Keap1 defense pathway: role in protection against drug-induced toxicity. Toxicology 2008;246:24–33. [PubMed: 18083283]

10. Halliwell, B.; Gutteridge, JMC. Free radicals in biology and medicine. Vol. 4. Oxford University Press; 2007.

  • 11. Rushmore TH, Morton MR, Pickett CB. The antioxidant responsive element. Actiavtion by oxidative stress and identification of the DNA consensus sequence required for functional activity. J Biol Chem 1991;266:11632–11639. [PubMed: 1646813]
  • 12. Rushmore TH, King RG, Paulson KE, Pickett CB. Regulation of glutathione S-transferase Ya subunit gene expression: identification of a unique xenobiotics-responsive element controlling inducible expression by planar aromatic compounds. Proc Natl Acad Sci USA 1990;87:3826–3830. [PubMed: 2160079]
  • 13. Xie T, Belinsky M, Xu Y, Jaiswal AK. ARE and TRE-mediated regulation of gene expression: response to xenobiotics and antioxidants. J Biol Chem 1995;270:6894–6900. [PubMed: 7896838]
  • 14.

Rushmore TH, Pickett CB. Glutathione S-transferases, structures, regulation, and therapeutic implications. J Biol Chem 1993;268:11475–11478. [PubMed: 8505281]

15. Jaiswal AK. Regulation of genes encoding NAD(P)H:quinone oxidoreductases. Free Radic Biol Med 2000;29:254–252. [PubMed: 11035254]

Advertisements

Read Full Post »