201
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Bieler S, Meiners S, Stangl V, Pohl T, Stangl K. Comprehensive proteomic and transcriptomic analysis reveals early induction of a protective anti-oxidative stress response by low-dose proteasome inhibition. Proteomics 2009; 9:3257-67. [PMID: 19562799 DOI: 10.1002/pmic.200800927] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Effective inhibition of the proteasome by high doses of proteasome inhibitors induces apoptotic cell death. In contrast, partial proteasome inhibition by low inhibitor doses mediates a protective cellular stress response. The early targets and mediators of these dose-dependent effects of proteasome inhibitors are unknown. Primary human umbilical cord vein endothelial cells were treated with low and high doses of the proteasome inhibitor MG132 for 2 h. In a combined 2-DE and MS approach, we identified more than 20 new targets of proteasome inhibition. These proteins are involved in cell cycle regulation, signaling, cytoskeletal rearrangement, and cellular stress response. Accompanying Affymetrix analysis revealed that these proteins are not regulated on the transcriptional level but are mainly stabilized by proteasome inhibition. The proteasome-dependent accumulation of the anti-oxidative sensor proteins DJ-1, peroxiredoxin-1 and -6 was accompanied by dose-dependent induction of oxidative stress after 2 h of proteasome inhibition and contributed to the differential transcriptional stress response to low- and high-dose proteasome inhibition: Whereas low-dose proteasome inhibition induces a transcriptional profile reminiscent of a physiological stress response that preconditions and protects endothelial cells from oxidative stress, high inhibitor doses induce massive transcriptional dysregulation and pronounced oxidative stress triggering apoptosis.
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Affiliation(s)
- Sven Bieler
- Medizinische Klinik mit Schwerpunkt Kardiologie und Angiologie, Charité-Universitaetsmedizin Berlin, Berlin, Germany
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202
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Zhao F, Wu T, Lau A, Jiang T, Huang Z, Wang XJ, Chen W, Wong PK, Zhang DD. Nrf2 promotes neuronal cell differentiation. Free Radic Biol Med 2009; 47:867-79. [PMID: 19573594 PMCID: PMC2748111 DOI: 10.1016/j.freeradbiomed.2009.06.029] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/07/2009] [Revised: 06/19/2009] [Accepted: 06/22/2009] [Indexed: 11/24/2022]
Abstract
The transcription factor Nrf2 has emerged as a master regulator of the endogenous antioxidant response, which is critical in defending cells against environmental insults and in maintaining intracellular redox balance. However, whether Nrf2 has any role in neuronal cell differentiation is largely unknown. In this report, we have examined the effects of Nrf2 on cell differentiation using a neuroblastoma cell line, SH-SY5Y. Retinoic acid (RA) and 12-O-tetradecanoylphorbol 13-acetate, two well-studied inducers of neuronal differentiation, are able to induce Nrf2 and its target gene NAD(P)H quinone oxidoreductase 1 in a dose- and time-dependent manner. RA-induced Nrf2 up-regulation is accompanied by neurite outgrowth and an induction of two neuronal differentiation markers, neurofilament-M and microtubule-associated protein 2. Overexpression of Nrf2 in SH-SY5Y cells promotes neuronal differentiation, whereas inhibition of endogenous Nrf2 expression inhibited neuronal differentiation. More remarkably, the positive role of Nrf2 in neuronal differentiation was verified ex vivo in primary neuron culture. Primary neurons isolated from Nrf2-null mice showed a retarded progress in differentiation, compared to those from wild-type mice. Collectively, our data demonstrate a novel role for Nrf2 in promoting neuronal cell differentiation, which will open new perspectives for therapeutic uses of Nrf2 activators in patients with neurodegenerative diseases.
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Affiliation(s)
- Fei Zhao
- Department of Pharmacology and Toxicology, University of Arizona, Tucson, AZ, USA
| | - Tongde Wu
- Department of Pharmacology and Toxicology, University of Arizona, Tucson, AZ, USA
| | - Alexandria Lau
- Department of Pharmacology and Toxicology, University of Arizona, Tucson, AZ, USA
| | - Tao Jiang
- Department of Pharmacology and Toxicology, University of Arizona, Tucson, AZ, USA
| | - Zheping Huang
- Department of Pharmacology and Toxicology, University of Arizona, Tucson, AZ, USA
| | - Xiao-Jun Wang
- Department of Pharmacology and Toxicology, University of Arizona, Tucson, AZ, USA
| | - Weimin Chen
- Department of Pharmacology and Toxicology, University of Arizona, Tucson, AZ, USA
| | - Pak Kin Wong
- Department of Aerospace and Mechanical Engineering, University of Arizona, Tucson, AZ, USA
| | - Donna D. Zhang
- Address correspondence and reprint requests to Donna D. Zhang, Department of Pharmacology and Toxicology, University of Arizona, 1703 E Mabel St, Tucson, AZ, 85721. Tel: 1-520-626-9918, Fax: 1-520 626 2466;
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203
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Dreger H, Westphal K, Wilck N, Baumann G, Stangl V, Stangl K, Meiners S. Protection of vascular cells from oxidative stress by proteasome inhibition depends on Nrf2. Cardiovasc Res 2009; 85:395-403. [PMID: 19679681 DOI: 10.1093/cvr/cvp279] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
AIMS Increased levels of reactive oxygen species cause oxidative stress and severely damage lipids, proteins, and DNA. We have previously shown that partial proteasome inhibition induces an antioxidative gene pattern in endothelial cells. Here, we elucidate the mechanisms of proteasome inhibitor-mediated upregulation of antioxidative enzymes and cytoprotection. METHODS AND RESULTS Non-toxic proteasome inhibition upregulated mRNA and protein expression of superoxide dismutase 1 (SOD1) and haem oxygenase 1 (HO1) in several human endothelial and vascular smooth muscle cell types. Transcriptional activation of these enzymes was shown by inhibition of RNA polymerase II and nuclear run-on assays. Transfection of endothelial cells with luciferase reporter constructs revealed that upregulation can be largely confined to an antioxidant response element (ARE), which proved to be sufficient for transcriptional activation of SOD1 and HO1. Co-transfection studies and bandshift analyses confirmed binding of the antioxidative transcription factor NF-E2-related factor 2 (Nrf2)-which was stabilized by proteasome inhibition as shown by immunoblots-to the ARE site of HO1. Experiments with aortic endothelial and smooth muscle cells from Nrf2 wild-type and knockout mice revealed an essential role of Nrf2: in wild-type cells, proteasome inhibitor-mediated induction of SOD1 and HO1 was accompanied by protection of vascular cells against oxidative stress as determined by lactate dehydrogenase release assays. In contrast, proteasome inhibitor-mediated induction of antioxidative enzymes and cytoprotection were completely lost in cells from Nrf2 knockout mice. CONCLUSION Nrf2-dependent transcriptional activation of antioxidative enzymes is crucial for proteasome inhibitor-mediated protection of vascular cells against oxidative stress.
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Affiliation(s)
- Henryk Dreger
- Medizinische Klinik für Kardiologie und Angiologie, Charité - Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany
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204
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Hrdina J, Banning A, Kipp A, Loh G, Blaut M, Brigelius-Flohé R. The gastrointestinal microbiota affects the selenium status and selenoprotein expression in mice. J Nutr Biochem 2009; 20:638-48. [DOI: 10.1016/j.jnutbio.2008.06.009] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2008] [Revised: 06/12/2008] [Accepted: 06/17/2008] [Indexed: 11/24/2022]
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205
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Piccirillo S, Filomeni G, Brüne B, Rotilio G, Ciriolo MR. Redox mechanisms involved in the selective activation of Nrf2-mediated resistance versus p53-dependent apoptosis in adenocarcinoma cells. J Biol Chem 2009; 284:27721-33. [PMID: 19643729 DOI: 10.1074/jbc.m109.014837] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have investigated the role of reactive oxygen species and thiol-oxidizing agents in the induction of cell death and have shown that adenocarcinoma gastric (AGS) cells respond differently to the oxidative challenge according to the signaling pathways activated. In particular, apoptosis in AGS cells is induced via the mitochondrial pathway upon treatment with thiol-oxidizing agents, such as diamide. Apoptosis is associated with persistent oxidative damage, as evidenced by the increase in carbonylated proteins and the expression/activation of DNA damage-sensitive proteins histone H2A.X and DNA-dependent protein kinase. Resistance to hydrogen peroxide is instead associated with Keap1 oxidation and rapid translocation of Nrf2 into the nucleus. Sensitivity to diamide and resistance to hydrogen peroxide are correlated with GSH redox changes, with diamide severely increasing GSSG, and hydrogen peroxide transiently inducing protein-GSH mixed disulfides. We show that p53 is activated in response to diamide treatment by the oxidative induction of the Trx1/p38(MAPK) signaling pathway. Similar results were obtained with another carcinoma cell line, CaCo2, indicating that these findings are not limited to AGS cells. Our data suggest that thiol-oxidizing agents could be exploited as inducers of apoptosis in tumor histotypes resistant to ROS-producing chemotherapeutics.
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Affiliation(s)
- Sara Piccirillo
- Department of Biology, University of Rome Tor Vergata, 00133 Rome, Italy
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206
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Brigelius-Flohé R, Banning A. Part of the Series: From dietary antioxidants to regulators in cellular signaling and gene regulation. Free Radic Res 2009; 40:775-87. [PMID: 17015256 DOI: 10.1080/10715760600722643] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
The association of decreased cancer risk with intake of cruciferous vegetables and selenium is stronger than that reported for fruits and vegetables in general. An active constituent in cruciferae is sulforaphane. Chemopreventive effects of both, sulforaphane and selenium have been attributed to an antioxidant action which certainly is too simplicistic. Sulforaphane induces via activation of the Nrf2/Keap1 system phase 2 enzymes that protect against carcinogens and oxidants. Induced enzymes comprise the selenoproteins thioredoxin reductase-1 (TrxR1) and gastrointestinal glutathione peroxidase (GI-GPx, GPx2), which contain antioxidant response elements (ARE) in their promoter regions. Translational realisation of the enhanced transcripts depends on adequate selenium supply, which explains the synergism of Nrf2 activators and selenium. Regarding tumorigenesis the role of TrxR1 is ambiguous: it is essential for fast tumor cell growth but also diminishes vascularisation of tumors. The anticarcinogenic role of GI-GPx is evident from enhanced gastrointestinal tumor formation in gpx2/gpx1 double KO mice.
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Affiliation(s)
- Regina Brigelius-Flohé
- German Institute of Human Nutrition, Potsdam-Rehbruecke, Arthur-Scheunert-Allee 114 - 116, D-14558, Nuthetal, Germany.
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207
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Wagner AE, Ernst I, Iori R, Desel C, Rimbach G. Sulforaphane but not ascorbigen, indole-3-carbinole and ascorbic acid activates the transcription factor Nrf2 and induces phase-2 and antioxidant enzymes in human keratinocytes in culture. Exp Dermatol 2009; 19:137-44. [PMID: 19558496 DOI: 10.1111/j.1600-0625.2009.00928.x] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Nrf2 is a basic leucine zipper transcriptional activator essential for the coordinated transcriptional induction of phase-2 and antioxidant enzymes. Brassica vegetables contain phytochemicals including glucoraphanin, the precursor of sulforaphane (SFN) and glucobrassicin, the precursor of indole-3-carbinole (I3C) and ascorbigen (ABG). The degradation products SFN, I3C and ABG may be capable of inducing cytoprotective genes in skin. In this study, we tested the potency of SFN, ABG and I3C in affecting Nrf2-dependent gene expression in human keratinocytes in culture. SFN but not ABG and its precursors I3C and ascorbic acid induced Nrf2 dependent gene expression at a relatively low concentration (5 micromol/l). Induction of Nrf2 due to SFN was accompanied by an increase in mRNA and protein levels of NADPH quinone oxidoreductase 1, heme oxygenase 1 and gamma-glutamylcysteine-synthetase. Furthermore, SFN elevated cellular glutathione levels and antagonized tumor necrosis factor-alpha-induced NFkappaB transactivation. Therefore, SFN treatment may present a strategy for enhancing the cellular defense mechanisms in skin.
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Affiliation(s)
- Anika E Wagner
- Institute of Human Nutrition and Food Science, Christian-Albrechts-University, Kiel, Germany
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208
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Huang Z, Li J, Zhang S, Zhang X. Inorganic arsenic modulates the expression of selenoproteins in mouse embryonic stem cell. Toxicol Lett 2009; 187:69-76. [DOI: 10.1016/j.toxlet.2009.01.024] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2008] [Revised: 01/18/2009] [Accepted: 01/20/2009] [Indexed: 12/15/2022]
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209
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Higgins LG, Kelleher MO, Eggleston IM, Itoh K, Yamamoto M, Hayes JD. Transcription factor Nrf2 mediates an adaptive response to sulforaphane that protects fibroblasts in vitro against the cytotoxic effects of electrophiles, peroxides and redox-cycling agents. Toxicol Appl Pharmacol 2009; 237:267-80. [DOI: 10.1016/j.taap.2009.03.005] [Citation(s) in RCA: 133] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2008] [Revised: 02/06/2009] [Accepted: 03/11/2009] [Indexed: 01/10/2023]
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210
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Kulinsky VI, Kolesnichenko LS. The glutathione system. I. Synthesis, transport, glutathione transferases, glutathione peroxidases. BIOCHEMISTRY MOSCOW-SUPPLEMENT SERIES B-BIOMEDICAL CHEMISTRY 2009. [DOI: 10.1134/s1990750809020036] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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211
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Matsumoto S, Jin M, Dewa Y, Nishimura J, Moto M, Murata Y, Shibutani M, Mitsumori K. Suppressive effect of Siraitia grosvenorii extract on dicyclanil-promoted hepatocellular proliferative lesions in male mice. J Toxicol Sci 2009; 34:109-18. [PMID: 19182440 DOI: 10.2131/jts.34.109] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Dicyclanil (DC) generates reactive oxygen species (ROS) due to Cyp1a1 induction, and DNA damage caused by oxidative stress is probably involved in hepatocarcinogenesis in mice. To clarify the modifying effect of the Siraitia grosvenorii extract (SGE), which has antioxidative properties, we employed a 2-stage liver carcinogenesis model in partially hepatectomized male ICR mice. Mice maintained on diet containing DC at a concentration of 1,500 ppm for 9 weeks after a single intraperitoneal injection of diethylnitrosamine (DEN) at a dose of 30 mg/kg and they were given water containing 2,500 ppm of SGE for 11 weeks including 2 weeks as pre-administration on DC. SGE inhibited the induction of gamma-glutamyltranspeptidase-positive hepatocytes, lipid peroxidation, and gene expression of Cyp1a1, all of which were caused by DC. To examine whether SGE indirectly inhibits Cyp1a1 expression induced by inhibition of aryl hydrocarbon receptor (Ahr)-mediated signal transduction caused by DC, mice with high (C57BL/6J mice) and low affinities (DBA/2J mice) to Ahr were given DC-containing diet and/or SGE-containing tap water for 2 weeks. Cyp1a1 gene expression was significantly lower in C57BL/6J mice administered DC + SGE than in C57BL/6J mice administered DC alone; there was no difference in the Cyp1a1 expression between DBA/2J mice administered DC + SGE and DC alone. These results suggest that SGE suppresses the induction of Cyp1a1, leading to inhibition of ROS generation and consequently inhibited hepatocarcinogenesis, probably due to suppression of Ahr activity.
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Affiliation(s)
- Sayaka Matsumoto
- Laboratory of Veterinary Pathology, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu-shi, Tokyo 183-8509, Japan
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212
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Nrf2-dependent upregulation of antioxidative enzymes: a novel pathway for proteasome inhibitor-mediated cardioprotection. Cardiovasc Res 2009; 83:354-61. [DOI: 10.1093/cvr/cvp107] [Citation(s) in RCA: 161] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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213
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Brigelius-Flohé R, Kipp A. Glutathione peroxidases in different stages of carcinogenesis. Biochim Biophys Acta Gen Subj 2009; 1790:1555-68. [PMID: 19289149 DOI: 10.1016/j.bbagen.2009.03.006] [Citation(s) in RCA: 217] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2009] [Revised: 03/05/2009] [Accepted: 03/08/2009] [Indexed: 01/12/2023]
Abstract
Cancer cells produce high amounts of reactive oxygen species (ROS) and evade apoptosis. Hydroperoxides support proliferation, invasion, migration and angiogenesis, but at higher levels induce apoptosis, thus being pro- and anti-carcinogenic. Accordingly, glutathione peroxidases (GPxs) regulating hydroperoxide levels might have dual roles too. GPx1, clearly an antioxidant enzyme, is down-regulated in many cancer cells. Its main role would be prevention of cancer initiation by ROS-mediated DNA damage. GPx2 is up-regulated in cancer cells. GPx1/GPx2 double knockout mice develop colitis and intestinal cancer. However, GPx2 knockdown cancer cells grow better in vitro and in vivo probably reflecting the physiological role of GPx2 in intestinal mucosa homeostasis. GPx2 counteracts COX-2 expression and PGE(2) production, which explains its potential to inhibit migration and invasion of cultured cancer cells. Overexpression of GPx3 inhibits tumor growth and metastasis. GPx4 is decreased in cancer tissues. GPx4-overexpressing cancer cells have low COX-2 activity and tumors derived therefrom are smaller than from control cells and do not metastasize. Collectively, GPxs prevent cancer initiation by removing hydroperoxides. GPx4 inhibits but GPx2 supports growth of established tumors. Metastasis, but also apoptosis, is inhibited by all GPxs. GPx-mediated regulation of COX/LOX activities may be relevant to early stages of inflammation-mediated carcinogenesis.
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Affiliation(s)
- Regina Brigelius-Flohé
- Department Biochemistry of Micronutrients, German Institute of Human Nutrition Potsdam-Rehbruecke, Arthur-Scheunert-Allee 114-116, D-14558 Nuthetal, Germany.
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214
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Banning A, Kipp A, Schmitmeier S, Löwinger M, Florian S, Krehl S, Thalmann S, Thierbach R, Steinberg P, Brigelius-Flohé R. Glutathione Peroxidase 2 Inhibits Cyclooxygenase-2–Mediated Migration and Invasion of HT-29 Adenocarcinoma Cells but Supports Their Growth as Tumors in Nude Mice. Cancer Res 2008; 68:9746-53. [DOI: 10.1158/0008-5472.can-08-1321] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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215
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Pappas A, Zoidis E, Surai P, Zervas G. Selenoproteins and maternal nutrition. Comp Biochem Physiol B Biochem Mol Biol 2008; 151:361-72. [DOI: 10.1016/j.cbpb.2008.08.009] [Citation(s) in RCA: 135] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2008] [Revised: 08/13/2008] [Accepted: 08/20/2008] [Indexed: 11/24/2022]
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216
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Abstract
Cells exposed to oxidative stress or electrophilic xenobiotics respond by transcriptionally up-regulating a battery of genes that contain a cis-acting element in their promoter region known as the antioxidant/electrophile response element (ARE). Mutational analysis of the promoter regions of ARE-containing genes led to the creation of two different models for the ARE; a core ARE (cARE: RTGACnnnGC) and an extended ARE (eARE: TMAnnRTGAYnnnGCAwwww). Using bioinformatic software we have aligned the promoter regions of several ARE-containing genes to produce two position-specific probability matrices that independently describe the cARE and eARE. These matrices can also be used to quantitatively assess putative AREs.
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Affiliation(s)
- Donald E Nerland
- Department of Pharmacology & Toxicology, Health Sciences Center, University of Louisville, Louisville, KY, USA.
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217
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Lau A, Villeneuve NF, Sun Z, Wong PK, Zhang DD. Dual roles of Nrf2 in cancer. Pharmacol Res 2008; 58:262-70. [PMID: 18838122 DOI: 10.1016/j.phrs.2008.09.003] [Citation(s) in RCA: 527] [Impact Index Per Article: 31.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/18/2008] [Revised: 09/07/2008] [Accepted: 09/08/2008] [Indexed: 02/07/2023]
Abstract
In response to oxidative stress, the transcription factor NF-E2-related factor 2 (Nrf2) controls the fate of cells through transcriptional upregulation of antioxidant response element (ARE)-bearing genes, including those encoding endogenous antioxidants, phase II detoxifying enzymes, and transporters. Expression of the Nrf2-dependent proteins is critical for ameliorating or eliminating toxicants/carcinogens to maintain cellular redox homeostasis. As a result, activation of the Nrf2 pathway, by naturally-occurring compounds or synthetic chemicals at sub-toxic doses, confers protection against subsequent toxic/carcinogenic exposure. Thus, the use of dietary compounds or synthetic chemicals to boost the Nrf2-dependent adaptive response to counteract environmental insults has emerged to be a promising strategy for cancer prevention. Interestingly, recent emerging data has revealed the "dark" side of Nrf2. Nrf2 and its downstream genes are overexpressed in many cancer cell lines and human cancer tissues, giving cancer cells an advantage for survival and growth. Furthermore, Nrf2 is upregulated in resistant cancer cells and is thought to be responsible for acquired chemoresistance. Therefore, it may be necessary to inhibit the Nrf2 pathway during chemotherapy. This review is primarily focused on the role of Nrf2 in cancer, with emphasis on the recent findings indicating the cancer promoting function of Nrf2 and its role in acquired chemoresistance.
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Affiliation(s)
- Alexandria Lau
- Department of Pharmacology and Toxicology, University of Arizona, Tucson, AZ 85721, USA
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218
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Habeos IG, Ziros PG, Chartoumpekis D, Psyrogiannis A, Kyriazopoulou V, Papavassiliou AG. Simvastatin activates Keap1/Nrf2 signaling in rat liver. J Mol Med (Berl) 2008; 86:1279-85. [PMID: 18787804 DOI: 10.1007/s00109-008-0393-4] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2008] [Revised: 07/02/2008] [Accepted: 07/30/2008] [Indexed: 12/17/2022]
Abstract
Some of the statins' pleiotropic actions have been attributed to their antioxidant activity. The Nrf2 transcription factor controls the expression of a number of protective genes in response to oxidative stress. In the present study, wistar rats, primary hepatocytes as well as ST2 cells, were employed to explore the potential role of Nrf2 in mediating the reported antioxidant effects of statins. Simvastatin triggered nuclear translocation of Nrf2 in rat liver and in primary rat hepatocytes in a mevalonate-dependent and cholesterol-independent way. In liver, nuclear extracts from simvastatin-treated rats, the DNA-binding activity of Nrf2, was significantly increased and the mRNA of two known targets of Nrf2 (HO-1 and GPX2) was induced. In ST2 cells stably transfected with constructs bearing Nrf2-binding site (antioxidant responsive element), simvastatin enhanced Nrf2-mediated transcriptional activity in a mevalonate-dependent and cholesterol-independent fashion. In conclusion, activation of Keap1/Nrf2 signaling pathway by simvastatin might provide effective protection of the cell from the deleterious effects of oxidative stress.
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Affiliation(s)
- Ioannis G Habeos
- Department of Internal Medicine, School of Medicine, University of Patras, 26500, Patras, Greece
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219
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Tosatto SCE, Bosello V, Fogolari F, Mauri P, Roveri A, Toppo S, Flohé L, Ursini F, Maiorino M. The catalytic site of glutathione peroxidases. Antioxid Redox Signal 2008; 10:1515-26. [PMID: 18500926 DOI: 10.1089/ars.2008.2055] [Citation(s) in RCA: 123] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
In GPxs, the redox-active Se or S, is at hydrogen bonding distance from Gln and Trp residues that contribute to catalysis. From sequence homology of >400 sequences and modeling of the DmGPx as a paradigm, Asn136 emerged as a fourth essential component of the active site. Mutational substitution of Asn136 by His, Ala, or Asp results in a dramatic decline of specific activity. Kinetic analysis indicates that k(+1), the rate constant for the oxidation of the enzyme, decreases by two to three orders of magnitude, whereas the reductive steps characterized by k'(+2) are less affected. Accordingly, MS/MS analysis shows that in Asn136 mutants, the peroxidatic Cys45 stays largely reduced also in the presence of a hydroperoxide, whereas in the wild-type enzyme, it is oxidized, forming a disulfide with the resolving Cys. Computational calculation of pK(a) values indicates that the residues facing the catalytic thiol, Asn136, Gln80, and, to a lesser extent Trp135, contribute to the dissociation of the thiol group, Asn136 being most relevant. These data disclose that the catalytic site of GPxs has to be redrawn as a tetrad, including Asn136, and suggest a mechanism accounting for the extraordinary catalytic efficiency of GPxs.
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220
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Banning A, Florian S, Deubel S, Thalmann S, Müller-Schmehl K, Jacobasch G, Brigelius-Flohé R. GPx2 counteracts PGE2 production by dampening COX-2 and mPGES-1 expression in human colon cancer cells. Antioxid Redox Signal 2008; 10:1491-500. [PMID: 18479189 DOI: 10.1089/ars.2008.2047] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
GPx2, the gastrointestinal glutathione peroxidase, is a selenoprotein predominantly expressed in the intestine. An anti-inflammatory and anticarcinogenic potential has been inferred from the development of colitis and intestinal cancer in GPx1 and GPx2 double knockout mice. Further, induction by Nrf2 activators classifies GPx2 as a protective enzyme. In contrast, enhanced COX-2 expression is consistently associated with inflammation. The antagonistic roles and an intriguing co-localization of GPx2 and COX-2 prompted us to investigate their possible mutual regulation. Both enzymes were upregulated in tissues of patients with colorectal cancer and colitis, and co-localized in the endoplasmic reticulum. A stable knockdown of GPx2 in HT-29 cells by siRNA resulted in a high basal and IL-1-induced expression of COX-2 and mPGES-1, enzymes required for the production of the pro-inflammatory PGE(2). Accordingly, si-GPx2 cells released high concentrations of PGE(2). Observed effects were specific for GPx2, since COX-2 and mPGES-1 expression was not affected by selenium-deprivation which resulted in the disappearance of GPx1. It is concluded that GPx2 by compartmentalized removal of hydroperoxides silences COX-2 activity and suppresses PGE(2)-dependent COX-2 expression. Thus, GPx2 may prevent undue responses to inflammatory stimuli and, in consequence, inflammation-driven initiation of carcinogenesis.
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Affiliation(s)
- Antje Banning
- German Institute of Human Nutrition Potsdam-Rehbruecke, Nuthetal, Germany
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221
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Abstract
Selenium is an essential micronutrient for man and animals. The role of selenium has been attributed largely to its presence in selenoproteins as the 21st amino acid, selenocysteine (Sec, U). Sec is encoded by TGA in DNA. A unique mechanism is used to decode the UGA codon in mRNA to co-translationally incorporate Sec into the growing polypeptide because there is no free pool of Sec. In the human genome, 25 genes for selenoproteins have been identified. Selenoproteins such as glutathione peroxidases, thioredoxin reductases, and iodothyronine deiodinases are involved in redox reactions, and Sec is an active-site residue essential for catalytic activity. Selenoproteins have biological functions in oxidoreductions, redox signaling, antioxidant defense, thyroid hormone metabolism, and immune responses. They thus possess a strong correlation with human diseases such as cancer, Keshan disease, virus infections, male infertility, and abnormalities in immune responses and thyroid hormone function.
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Affiliation(s)
- Jun Lu
- Medical Nobel Institute for Biochemistry, Department of Medical Biochemistry and Biophysics, Karolinska Institute, SE-17177 Stockholm, Sweden
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222
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Abstract
An adequate selenium (Se) status has for long been considered to prevent the development of various forms of cancer. However, underlying molecular mechanisms remained unknown. In mammals, selenium exerts its functions as selenocysteine incorporated into selenoproteins. Therefore, Se compounds can either act as Se source for selenoproteins or, depending on their chemical forms, in distinct ways. Most potent chemopreventive effects have been attributed to compounds in which the Se moiety is methylated. These compounds are able to induce phase 2 enzymes which are involved in the cellular defense system that is regulated by the Nrf2 transcription factor. Selenoproteins best studied in cancer development are members of the glutathione peroxidase (GPx) and thioredoxin reductase (TrxR) family. In various cancer cells and tissues, GPx2 and/or TrxR1 are up-regulated. Interestingly, both enzymes are targets of Nrf2. An enhanced expression of these enzymes may represent a mechanism to counteract carcinogenic pathways. They may, however, also provide a selective advantage for pre-existing tumor cells in guaranteeing survival and continuous proliferation.
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Affiliation(s)
- Regina Brigelius-Flohé
- Department Biochemistry of Micronutrients, German Institute of Human Nutrition, Potsdam-Rehbruecke, Arthur-Scheunert-Allee 114-116, D-14558 Nuthetal.
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223
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Zhu H, Jia Z, Zhang L, Yamamoto M, Misra HP, Trush MA, Li Y. Antioxidants and phase 2 enzymes in macrophages: regulation by Nrf2 signaling and protection against oxidative and electrophilic stress. Exp Biol Med (Maywood) 2008; 233:463-74. [PMID: 18367636 DOI: 10.3181/0711-rm-304] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Macrophages play important roles in immunity and other physiological processes. They are also target cells of various toxic agents, including oxidants and electrophiles. However, little is known regarding the molecular regulation and chemical inducibility of a spectrum of endogenous antioxidants and phase 2 enzymes in normal macrophages. Understanding the molecular pathway(s) controlling the coordinated expression of various macrophage antioxidants and phase 2 defenses is of importance for developing strategies to protect against macrophage injury induced by oxidants and electrophiles. Accordingly, this study was undertaken to determine the role of the nuclear factor E2-related factor 2 (Nrf2) in regulating both constitutive and chemoprotectant-inducible expression of various antioxidants and phase 2 enzymes in mouse macrophages. The constitutive expression of a series of antioxidants and phase 2 enzymes was significantly lower in macrophages derived from Nrf2-null (Nrf2(-/-)) mice than those from wild-type (Nrf2(+/+)) littermates. Incubation of wild-type macrophages with 3H-1,2-dithiole-3-thione (D3T) led to significant induction of various antioxidants and phase 2 enzymes, including catalase, glutathione, glutathione peroxidase (GPx), glutathione reductase, glutathione S-transferase, and NAD(P)H:quinone oxidoreductase 1. The inducibility of the above cellular defenses except for GPx by D3T was completely abolished in Nrf2(-/-) macrophages. As compared with wild-type cells, Nrf2(- /-) macrophages were much more susceptible to cell injury induced by reactive oxygen/nitrogen species, as well as two known macrophage toxins, acrolein and cadmium. Up-regulation of the antioxidants and phase 2 enzymes by D3T in wild-type macrophages resulted in increased resistance to the above oxidant-and electrophile-induced cell injury, whereas D3T treatment of Nrf2(- /-) macrophages provided only marginal or no cytoprotec-tion. This study demonstrates that Nrf2 is an indispensable factor in controlling both constitutive and inducible expression of a wide spectrum of antioxidants and phase 2 enzymes in macrophages as well as the susceptibility of these cells to oxidative and electrophilic stress.
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Affiliation(s)
- Hong Zhu
- Division of Biomedical Sciences, Edward Via Virginia College of Osteopathic Medicine, Virginia Tech Corporate Research Center Research Building II, 1861 Pratt Drive, Blacksburg, VA 24060, USA
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224
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Rokushima M, Fujisawa K, Furukawa N, Itoh F, Yanagimoto T, Fukushima R, Araki A, Okada M, Torii M, Kato I, Ishizaki J, Omi K. Transcriptomic Analysis of Nephrotoxicity Induced by Cephaloridine, a Representative Cephalosporin Antibiotic. Chem Res Toxicol 2008; 21:1186-96. [DOI: 10.1021/tx800008e] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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225
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Nuclear factor E2-related factor 2-dependent myocardiac cytoprotection against oxidative and electrophilic stress. Cardiovasc Toxicol 2008; 8:71-85. [PMID: 18463988 DOI: 10.1007/s12012-008-9016-0] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/02/2008] [Accepted: 04/11/2008] [Indexed: 02/07/2023]
Abstract
Nuclear factor E2-related factor 2 (Nrf2) is a critical regulator of cytoprotective gene expression. However, the role of this transcription factor in myocardiac cytoprotection against oxidative and electrophilic stress remains unknown. This study was undertaken to investigate if Nrf2 signaling could control the constitutive and inducible expression of antioxidants and phase 2 enzymes in primary cardiomyocytes as well as the susceptibility of these cells to oxidative and electrophilic injury. The basal expression of a series of antioxidants and phase 2 enzymes was significantly lower in cardiomyocytes from Nrf2(-/-) mice than those from wild-type littermates. Incubation of wild-type cardiomyocytes with 3H-1,2-dithiole-3-thione (D3T) led to significant induction of various antioxidants and phase 2 enzymes, including catalase, glutathione, glutathione peroxidase (GPx), glutathione reductase, glutathione S-transferase, NAD(P)H:quinone oxidoreductase 1, and heme oxygenase-1. The inducibility of the above cellular defenses except GPx by D3T was abolished in Nrf2(-/-) cardiomyocytes. As compared to wild-type cells, Nrf2(-/-) cardiomyocytes were much more susceptible to cell injury induced by H(2)O(2), peroxynitrite, and 4-hydroxy-2-nonenal. Treatment of wild-type cardiomyocytes with D3T, which upregulated the cellular defenses, resulted in increased resistance to the above oxidant- and electrophile-induced cell injury, whereas D3T treatment of Nrf2(-/-) cardiomyocytes provided no cytoprotection. This study demonstrates that Nrf2 is an important factor in controlling both constitutive and inducible expression of a wide spectrum of antioxidants and phase 2 enzymes in cardiomyocytes and is responsible for protecting these cells against oxidative and electrophilic stress. These findings also implicate Nrf2 as an important signaling molecule for myocardiac cytoprotection.
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226
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Abstract
Emerging evidence suggests that dietary phytochemicals, in particular flavonoids, may exert beneficial effects on the central nervous system by protecting neurons against stress-induced injury, by suppressing neuroinflammation and by improving cognitive function. It is likely that flavonoids exert such effects, through selective actions on different components of a number of protein kinase and lipid kinase signalling cascades, such as the phosphatidylinositol-3 kinase (PI3K)/Akt, protein kinase C and mitogen-activated protein kinase (MAPK) pathways. This review explores the potential inhibitory or stimulatory actions of flavonoids within these pathways, and describes how such interactions are likely to underlie neurological effects through their ability to affect the activation state of target molecules and/or by modulating gene expression. Future research directions are outlined in relation to the precise site(s) of action of flavonoids within signalling pathways and the sequence of events that allow them to regulate neuronal function.
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227
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Burk RF, Hill KE, Nakayama A, Mostert V, Levander XA, Motley AK, Johnson DA, Johnson JA, Freeman ML, Austin LM. Selenium deficiency activates mouse liver Nrf2-ARE but vitamin E deficiency does not. Free Radic Biol Med 2008; 44:1617-23. [PMID: 18279678 PMCID: PMC2346531 DOI: 10.1016/j.freeradbiomed.2008.01.016] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/01/2007] [Revised: 01/10/2008] [Accepted: 01/15/2008] [Indexed: 11/24/2022]
Abstract
Selenium (Se) and vitamin E are antioxidant micronutrients. Se functions through selenoproteins and vitamin E reacts with oxidizing molecules in membranes. The relationship of these micronutrients with the Nrf2-antioxidant response element (ARE) pathway was investigated using ARE-reporter mice and Nrf2-/- mice. Weanling males were fed Se-deficient (0 Se), vitamin E-deficient (0 E), or control diet for 16 or 22 weeks. The ARE reporter was elevated 450-fold in 0 Se liver but was not elevated in 0 E liver. Antioxidant enzymes induced by Nrf2-ARE (glutathione S-transferase (GST), NAD(P)H quinone oxidoreductase (NQOR), and heme oxygenase-1 (HO-1)) were elevated in 0 Se livers but not in 0 E livers. Deletion of Nrf2 had varying effects on the inductions, with GST induction being abolished by it but induction of NQOR and HO-1 still occurring. Thus, Se deficiency, but not vitamin E deficiency, induces a number of enzymes that protect against oxidative stress and modify xenobiotic metabolism through Nrf2-ARE and other stress-response pathways. We conclude that Se deficiency causes cytosolic oxidative stress but that vitamin E deficiency does not. This suggests that the oxidant defense mechanisms in which these antioxidant nutrients function are independent of one another.
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Affiliation(s)
- Raymond F Burk
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN 37232-0252, USA.
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228
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Abstract
Some members of the Prx family are up-regulated in cells under stress conditions. Prx I is the major cytoplasmic Prx and is known as a stress-inducible antioxidant enzyme. Various stress agents or conditions activate Prx I gene expression in vitro and in vivo. The transcription factor Nrf2 and its inhibitor Keap1 play an essential role in the regulation of the stress-induced Prx I gene activation through the ARE/EpRE (antioxidant/electrophile response element). The expression levels of Prx II and III are also up-regulated under stress conditions, although the molecular mechanisms of their up-regulation have not yet been thoroughly studied. Gene expression of both Prx I and II is activated by X-ray irradiation of the testis. Mitochondrial Prx III is up-regulated by stress agents in both cultured cells and experimental animals. The up-regulation of the Prxs in cells and tissues under oxidative stress conditions is one of the cellular recovery responses after oxidative damage.
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Affiliation(s)
- Tetsuro Ishii
- Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba, Ibaraki, 305-8575 Japan
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229
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Liu GH, Qu J, Shen X. NF-kappaB/p65 antagonizes Nrf2-ARE pathway by depriving CBP from Nrf2 and facilitating recruitment of HDAC3 to MafK. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2008; 1783:713-27. [PMID: 18241676 DOI: 10.1016/j.bbamcr.2008.01.002] [Citation(s) in RCA: 524] [Impact Index Per Article: 30.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2007] [Revised: 12/31/2007] [Accepted: 01/03/2008] [Indexed: 01/25/2023]
Abstract
Constitutively activated NF-kappaB occurs in many inflammatory and tumor tissues. Does it interfere with anti-inflammatory or anti-tumor signaling pathway? Here, we report that NF-kappaB p65 subunit repressed the Nrf2-antioxidant response element (ARE) pathway at transcriptional level. In the cells where NF-kappaB and Nrf2 were simultaneously activated, p65 unidirectionally antagonized the transcriptional activity of Nrf2. In the p65-overexpressing cells, the ARE-dependent expression of heme oxygenase-1 was strongly suppressed. However, p65 inhibited the ARE-driven gene transcription in a way that was independent of its own transcriptional activity. Two mechanisms were found to coordinate the p65-mediated repression of ARE: (1) p65 selectively deprives CREB binding protein (CBP) from Nrf2 by competitive interaction with the CH1-KIX domain of CBP, which results in inactivation of Nrf2. The inactivation depends on PKA catalytic subunit-mediated phosphorylation of p65 at S276. (2) p65 promotes recruitment of histone deacetylase 3 (HDAC3), the corepressor, to ARE by facilitating the interaction of HDAC3 with either CBP or MafK, leading to local histone hypoacetylation. This investigation revealed the participation of NF-kappaB p65 in the negative regulation of Nrf2-ARE signaling, and might provide a new insight into a possible role of NF-kappaB in suppressing the expression of anti-inflammatory or anti-tumor genes.
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Affiliation(s)
- Guang-Hui Liu
- Institute of Biophysics, Chinese Academy of Sciences, and Graduate School of the Chinese Academy of Sciences, Beijing, PR China
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230
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Programme schedule for SFRR-E Berlin supplement. Free Radic Res 2008; 42 Suppl 1:2-126. [DOI: 10.1080/10715760802207914] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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231
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Suzuki T, Kelly VP, Motohashi H, Nakajima O, Takahashi S, Nishimura S, Yamamoto M. Deletion of the Selenocysteine tRNA Gene in Macrophages and Liver Results in Compensatory Gene Induction of Cytoprotective Enzymes by Nrf2. J Biol Chem 2008; 283:2021-30. [DOI: 10.1074/jbc.m708352200] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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232
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Lee OH, Jain AK, Papusha V, Jaiswal AK. An Auto-regulatory Loop between Stress Sensors INrf2 and Nrf2 Controls Their Cellular Abundance. J Biol Chem 2007; 282:36412-20. [DOI: 10.1074/jbc.m706517200] [Citation(s) in RCA: 145] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
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233
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Shih PH, Yeh CT, Yen GC. Anthocyanins induce the activation of phase II enzymes through the antioxidant response element pathway against oxidative stress-induced apoptosis. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2007; 55:9427-9435. [PMID: 17935293 DOI: 10.1021/jf071933i] [Citation(s) in RCA: 202] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Reactive oxygen species (ROS)-induced cell damage is inevitable and severe and is involved in numerous diseases, including cancer. Reducing oxidative stress is one of the strategies of chemoprevention. Anthocyanins are naturally occurring flavonoids that show multiple benefits. We first pointed out the effects of anthocyanins in the contributions to activation of phase II antioxidant and detoxifying enzymes, chemopreventive potency, and involved transcriptional regulation. Our results obtained in rat liver Clone 9 cells showed that treatment of anthocyanins leads to positive effects on elevating the antioxidant capacity, including activated expression of glutathione-related enzymes (glutathione reductase, glutathione peroxidase, and glutathione S-transferase) and recruited GSH content. In addition, the activity of NAD(P)H: quinone oxidoreductase (NQO1) was also promoted under the treatment of anthocyanin. This influential functions as the defense system against programmed cell death induced by H2O2. The capacity for induction of luciferase expression by anthocyanins in cells transfected with rat nqo1-promoter constructed plasmid was further investigated; we found that the molecular mechanism is related to the activation of antioxidant response element (ARE) upstream of genes that are involved in antioxidation and detoxification. Our data suggest that natural anthocyanins are recommended as chemopreventive phytochemicals and could stimulate the antioxidant system to resist oxidant-induced injury. And, more important, the promoting effect of anthocyanins on ARE-regulated phase II enzyme expression seems to be a critical point in modulating the defense system against oxidative stress.
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Affiliation(s)
- Ping-Hsiao Shih
- Department of Food Science and Biotechnology, National Chung Hsing University, 250 Kuokuang Road, Taichung 40227, Taiwan
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234
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Kipp A, Banning A, Brigelius-Flohé R. Activation of the glutathione peroxidase 2 (GPx2) promoter by β-catenin. Biol Chem 2007; 388:1027-33. [DOI: 10.1515/bc.2007.137] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
AbstractGPx2, formerly named gastrointestinal glutathione peroxidase, is highly expressed in the proliferative area of the intestinal crypt-to-villus axis and in Paneth cells. Additionally, GPx2 is transiently up-regulated during development of gastrointestinal adenocarcinomas. Because both normal proliferation and differentiation of intestinal epithelial cells as well as carcinogenesis are regulated by the Wnt pathway, it was tested whether GPx2 may be a target of the β-catenin/TCF complex which transfers Wnt signals. The GPx2 promoter contains five putative β-catenin/TCF binding sites. Accordingly, the promoter was active in two cell lines with a constitutively active Wnt pathway, HepG2 and SW480, but not in BHK-21 cells in which the pathway is silent. Overexpression of β-catenin/TCF activated the GPx2 promoter in all three cell lines. Overexpression of wild-type adenomatous polyposis coli (APC) in SW480 cells which harbor a mutated APC gene decreased basal GPx2 promoter activity. Truncation of the promoter identified one β-catenin/TCF binding site that was sufficient for activation. Mutation of this site reduced the response to β-catenin/TCF by more than 50%. These findings suggest a function of GPx2 in the maintenance of normal renewal of the intestinal epithelium. Whether up-regulation of GPx2 during carcinogenesis supports tumor growth or can rather be considered as a counteracting effect remains to be investigated.
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235
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Aleksunes LM, Manautou JE. Emerging role of Nrf2 in protecting against hepatic and gastrointestinal disease. Toxicol Pathol 2007; 35:459-73. [PMID: 17562481 DOI: 10.1080/01926230701311344] [Citation(s) in RCA: 233] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Transcription factor NF-E2-related factor 2 (Nrf2) belongs to the basic region-leucine zipper family and is activated in response to electrophiles and reactive oxygen species. Nrf2 coordinately regulates the constitutive and inducible transcription of a wide array of genes involved in drug metabolism, detoxification, and antioxidant defenses. During periods of oxidative stress, Nrf2 is released from sequestration in the cytoplasm and translocates to the nucleus. Nrf2 binds antioxidant response elements (AREs) in the regulatory regions of target genes and activates transcription. Genetically modified mice lacking Nrf2 serve as a useful tool for identifying new ARE-regulated genes and assessing the ability of Nrf2 to confer protection against a variety of pathologies in numerous organs including the liver, intestine, lung, skin, and nervous system. With regards to the liver and gastrointestinal tract, Nrf2 knockout mice are more susceptible to acetaminophen-induced hepatocellular injury, benzo[a]pyrene-induced tumor formation and Fas- and TNFalpha -mediated hepatocellular apoptosis. The higher sensitivity of Nrf2 knockout mice to chemical toxicity is due in part to reduced basal and inducible expression of detoxification enzymes. Nrf2 may also be important in protecting against liver fibrosis, gallstone development, and formation of aberrant crypt foci. Research of Nrf2 has opened up new opportunities in understanding how antioxidant defense pathways are regulated, how oxidative stress contributes to disease progression and may serve as a novel target for designing therapies to prevent and treat diseases in which oxidative stress is implicated.
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Affiliation(s)
- Lauren M Aleksunes
- Department of Pharmaceutical Sciences, University of Connecticut, Storrs, Connecticut 06269-3092, USA
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236
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Shishodia S, Singh T, Chaturvedi MM. Modulation of transcription factors by curcumin. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2007; 595:127-48. [PMID: 17569208 DOI: 10.1007/978-0-387-46401-5_4] [Citation(s) in RCA: 140] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Curcumin is the active ingredient of turmeric that has been consumed as a dietary spice for ages. Turmeric is widely used in traditional Indian medicine to cure biliary disorders, anorexia, cough, diabetic wounds, hepatic disorders, rheumatism, and sinusitis. Extensive investigation over the last five decades has indicated that curcumin reduces blood cholesterol, prevents low-density lipoprotein oxidation, inhibits platelet aggregation, suppresses thrombosis and myocardial infarction, suppresses symptoms associated with type II diabetes, rheumatoid arthritis, multiple sclerosis, and Alzheimer's disease, inhibits HIV replication, enhances wound healing, protects from liver injury, increases bile secretion, protects from cataract formation, and protects from pulmonary toxicity and fibrosis. Evidence indicates that the divergent effects of curcumin are dependent on its pleiotropic molecular effects. These include the regulation of signal transduction pathways and direct modulation of several enzymatic activities. Most of these signaling cascades lead to the activation of transcription factors. Curcumin has been found to modulate the activity of several key transcription factors and, in turn, the cellular expression profiles. Curcumin has been shown to elicit vital cellular responses such as cell cycle arrest, apoptosis, and differentiation by activating a cascade of molecular events. In this chapter, we briefly review the effects of curcumin on transcription factors NF-KB, AP-1, Egr-1, STATs, PPAR-gamma, beta-catenin, nrf2, EpRE, p53, CBP, and androgen receptor (AR) and AR-related cofactors giving major emphasis to the molecular mechanisms of its action.
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Affiliation(s)
- Shishir Shishodia
- Department of Biology, Texas Southern University, Houston 77004, USA.
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237
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Affiliation(s)
- Shishir Shishodia
- Department of Biology, Texas Southern University, Houston, Texas, USA
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238
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Papp LV, Lu J, Holmgren A, Khanna KK. From selenium to selenoproteins: synthesis, identity, and their role in human health. Antioxid Redox Signal 2007; 9:775-806. [PMID: 17508906 DOI: 10.1089/ars.2007.1528] [Citation(s) in RCA: 867] [Impact Index Per Article: 48.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The requirement of the trace element selenium for life and its beneficial role in human health has been known for several decades. This is attributed to low molecular weight selenium compounds, as well as to its presence within at least 25 proteins, named selenoproteins, in the form of the amino acid selenocysteine (Sec). Incorporation of Sec into selenoproteins employs a unique mechanism that involves decoding of the UGA codon. This process requires multiple features such as the selenocysteine insertion sequence (SECIS) element and several protein factors including a specific elongation factor EFSec and the SECIS binding protein 2, SBP2. The function of most selenoproteins is currently unknown; however, thioredoxin reductases (TrxR), glutathione peroxidases (GPx) and thyroid hormone deiodinases (DIO) are well characterised selenoproteins involved in redox regulation of intracellular signalling, redox homeostasis and thyroid hormone metabolism. Recent evidence points to a role for selenium compounds as well as selenoproteins in the prevention of some forms of cancer. A number of clinical trials are either underway or being planned to examine the effects of selenium on cancer incidence. In this review we describe some of the recent progress in our understanding of the mechanism of selenoprotein synthesis, the role of selenoproteins in human health and disease and the therapeutic potential of some of these proteins.
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Affiliation(s)
- Laura Vanda Papp
- Queensland Institute of Medical Research, Cancer and Cell Biology Division, Herston, QLD, Australia
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239
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Muguruma M, Unami A, Kanki M, Kuroiwa Y, Nishimura J, Dewa Y, Umemura T, Oishi Y, Mitsumori K. Possible involvement of oxidative stress in piperonyl butoxide induced hepatocarcinogenesis in rats. Toxicology 2007; 236:61-75. [PMID: 17498859 DOI: 10.1016/j.tox.2007.03.025] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2007] [Revised: 03/27/2007] [Accepted: 03/28/2007] [Indexed: 12/20/2022]
Abstract
To clarify the possible mechanism of non-genotoxic hepatocarcinogenesis induced by piperonyl butoxide (PBO), male F344 rats were administered an i.p. injection of N-diethylnitrosamine (DEN) to initiate hepatocarcinogenesis. Two weeks later, the rats were administered a PBO-containing (0, 1, or 2%) diet for 6 weeks and subjected to a two-third partial hepatectomy 1 week later. After sacrificing them on week 8, their livers were histopathologically examined and analyzed for gene expression using a microarray and real-time RT-PCR. Reactive oxygen species (ROS) products were also measured using liver microsomes. Hepatocytes exhibited centrilobular hypertrophy and increased glutathione S-transferase placental form (GST-P) positive foci formation. ROS products increased significantly in liver microsomes. In the microarray analysis, the expressions of genes related to metabolism and oxidative stress - NAD(P)H dehydrogenase, quinone 1 (Nqo1), UDP-glucuronosyltransferase (UDPGTR-2), glutathione peroxidase 2 (Gpx2), glutathione reductase (GRx) - multidrug resistance associated protein 3 (Abcc3), and solute carrier family 7 (cationic amino acid transporter, y+ system) member 5 (Slc7a5) were up-regulated in the PBO group in comparison to the 0% PBO group; this was confirmed by real-time RT-PCR. Additionally, a significant up-regulation of stress response related genes such as CYP1A1 was observed in PBO-treated groups in real-time RT-PCR. HPLC analysis revealed that the level of 8-OHdG in the 2% PBO group was significantly higher than that in the 0% PBO group. This suggests that PBO has the potential to generate ROS via metabolic pathways and induce oxidative stress, including oxidative DNA damage, resulting in the induction of hepatocellular tumors in rats.
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Affiliation(s)
- Masako Muguruma
- Laboratory of Veterinary Pathology, Tokyo University of Agriculture and Technology, Fuchu City, Tokyo 183-8509, Japan.
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240
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Haton C, François A, Vandamme M, Wysocki J, Griffiths NM, Benderitter M. Imbalance of the antioxidant network of mouse small intestinal mucosa after radiation exposure. Radiat Res 2007; 167:445-53. [PMID: 17388695 DOI: 10.1667/rr0581.1] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2006] [Accepted: 10/25/2006] [Indexed: 11/03/2022]
Abstract
The aim of this study was to investigate acute variations in antioxidant defense systems in the intestinal mucosa after abdominal radiation exposure and the role played by radiation-induced inflammation in these variations. Antioxidant defense systems of mouse small intestinal mucosa were studied at 6 h and 4 days after abdominal radiation exposure. Superoxide dismutases, glutathione peroxidases, catalase, metallothioneins and thioredoxins were followed in terms of mRNA expression, protein expression and enzyme activities. Dexamethasone was administered to investigate the relationship between variations in mucosal antioxidant capacity and radiation-induced inflammation. Six hours after exposure, only mitochondrial-associated antioxidant systems were induced (the superoxide dismutase and thioredoxin 2). Four days after exposure, during the inflammatory phase, superoxide dismutases were decreased and modulations of the second line of the antioxidant network were also observed: Catalase was decreased and glutathione peroxidases and metallothioneins were induced. Dexamethasone treatment modulated only glutathione peroxidase expression and did not influence either metallothionein or superoxide dismutase expression. Our findings provide direct in vivo evidence that antioxidant mechanisms of the small intestinal mucosa were not markedly mobilized during the very acute tissue radiation response. During the radiation-induced acute inflammatory response, the antioxidant capacity appeared to be dependent on inflammatory status to a certain extent.
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Affiliation(s)
- Céline Haton
- Département de RadioProtection de l'Homme, Laboratoire de radiopathologie, Institut de Radioprotection et de Sûreté Nucléaire, Fontenay-aux-Roses, France
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241
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Kluth D, Banning A, Paur I, Blomhoff R, Brigelius-Flohé R. Modulation of pregnane X receptor- and electrophile responsive element-mediated gene expression by dietary polyphenolic compounds. Free Radic Biol Med 2007; 42:315-25. [PMID: 17210444 DOI: 10.1016/j.freeradbiomed.2006.09.028] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/20/2006] [Revised: 09/28/2006] [Accepted: 09/29/2006] [Indexed: 01/31/2023]
Abstract
Based on animal models, dietary polyphenols are predicted to be promising chemopreventive agents in humans. Allspice, clove, and thyme extracts as well as defined dietary polyphenolic compounds were, therefore, tested for their ability to activate mechanisms related to phase 1 enzymes, i.e., the PXR-regulated CYP3A4 promoter, and phase 2 enzymes, i.e. the EpRE-regulated promoters of gastrointestinal glutathione peroxidase (GI-GPx) and heme oxygenase-1 (HO-1), examples of Nrf2-regulated genes. From the compounds tested, clove and thyme extracts as well as curcumin and resveratrol activated the PXR. PXR activation correlated with the activation of the CYP3A4 promoter in the case of thyme extract, curcumin, and resveratrol, but not in the case of clove extract. Allspice extract, EGCG, and quercetin did not activate PXR but enhanced CYP3A4 promoter activity. Thyme extract and quercetin activated the EpRE of HO-1. Both significantly activated the GI-GPx promoter, effects that depended on a functional EpRE. Resveratrol did not activate the isolated EpRE but enhanced the GI-GPx promoter activity, whereas clove extract even inhibited it. It is concluded that individual polyphenols as well as polyphenol-rich plant extracts may affect phase 1 and 2 enzyme expression by distinct mechanisms that must be elucidated, before potential health effects can reliably be predicted.
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Affiliation(s)
- Dirk Kluth
- German Institute of Human Nutrition, Potsdam-Rehbrücke, Arthur-Scheunert-Allee 114-116, D-14558 Nuthetal, Germany
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242
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Mattes WB, Daniels KK, Summan M, Xu ZA, Mendrick DL. Tissue and species distribution of the glutathione pathway transcriptome. Xenobiotica 2007; 36:1081-121. [PMID: 17118919 DOI: 10.1080/00498250600861793] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
The goal of this study was to compare and contrast the basal gene expression levels of the various enzymes involved in glutathione metabolism among tissues and genders of the rat, mouse and canine. The approach taken was to use Affymetrix GeneChip microarray data for rat, mouse and canine tissues, comparing intensity levels for individual probes between tissues and genders. As was hypothesized, the relative expression in liver, lung, heart, kidney and testis varied from gene to gene, with differences of expression between tissues sometimes greater than a 1000-fold. The pattern of differential expression was usually similar between male and female animals, but varied greatly between the three species. Gstp1 appears to be expressed at high levels in male mouse liver, reasonable levels in canine liver, but very low levels in male rat liver. In all species examined, Gstp1 expression was below detectable levels in testis. Gsta3/Yc2 expression appeared high in rodent liver and female canine liver, but not male canine liver. Finally, Mgst1 and Gpx3 expression appeared to be lower in canine heart and testis than seen in rodents. Given the critical role of the glutathione pathway in the detoxification of many drugs and xenobiotics, the observed differences in basal tissue distribution among mouse, rat and canine has far-reaching implications in comparing responses of these species in safety testing.
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Affiliation(s)
- W B Mattes
- Department of Toxicogenomics Services, Gene Logic Inc, Gaithersburg, MD, USA.
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243
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Lyakhovich VV, Vavilin VA, Zenkov NK, Menshchikova EB. Active defense under oxidative stress. The antioxidant responsive element. BIOCHEMISTRY (MOSCOW) 2006; 71:962-74. [PMID: 17009949 DOI: 10.1134/s0006297906090033] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
This review considers the mechanisms and factors that stimulate transcription of genes regulated by the antioxidant responsive element (ARE). The latter is important for cell defense under conditions of oxidative stress and also for detoxification of electrophilic xenobiotics. There are differences in regulation of intracellular homeostasis involving Nrf2-mediated activation of ARE and other redox-sensitive factors (NF-kappaB and AP-1).
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Affiliation(s)
- V V Lyakhovich
- Institute of Molecular Biology and Biophysics, Siberian Branch of the Russian Academy of Medical Sciences, Novosibirsk 630117, Russia
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244
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Singh A, Rangasamy T, Thimmulappa RK, Lee H, Osburn WO, Brigelius-Flohé R, Kensler TW, Yamamoto M, Biswal S. Glutathione peroxidase 2, the major cigarette smoke-inducible isoform of GPX in lungs, is regulated by Nrf2. Am J Respir Cell Mol Biol 2006; 35:639-50. [PMID: 16794261 PMCID: PMC2643293 DOI: 10.1165/rcmb.2005-0325oc] [Citation(s) in RCA: 173] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2005] [Accepted: 06/01/2006] [Indexed: 02/01/2023] Open
Abstract
Disruption of NF-E2-related factor (Nrf2), a redox-sensitive basic leucine zipper transcription factor, causes early-onset and more severe emphysema due to chronic cigarette smoke. Nrf2 determines the susceptibility of lungs to cigarette smoke-induced emphysema in mice through the transcriptional induction of numerous antioxidant genes. The lungs of Nrf2-/- mice have higher oxidative stress as evident from the increased levels of lipid peroxidation (4-hydroxy-2-nonenal) and oxidative DNA damage (7,8-dihydro-8-Oxo-2'deoxyguanosine) in response to cigarette smoke. Glutathione peroxidases (GPX) are the primary antioxidant enzymes that scavenge hydrogen peroxide and organic hydroperoxides. Among the five GPX isoforms, expression of GPX2 was significantly induced at both mRNA and protein levels in the lungs of Nrf2+/+ mice, in response to cigarette smoke. Activation of Nrf2 by specific knock down of the cytosolic inhibitor of Nrf2, Keap1, by small inhibitory RNA (siRNA) upregulated the expression of GPx2, whereas Nrf2 siRNA down-regulated the expression of GPX2 in lung epithelial cells. An ARE sequence located in the 5' promoter-flanking region of exon 1 that is highly conserved between mouse, rat, and human was identified. Mutation of this ARE core sequence completely abolished the activity of promoter-reporter gene construct. The binding of Nrf2 to the GPX2 antioxidant response element was confirmed by chromatin immunoprecipation, electrophoretic mobility shift assays, and site-directed mutagenesis. This study shows that GPX2 is the major oxidative stress-inducible cellular GPX isoform in the lungs, and that its basal as well as inducible expression is dependent on Nrf2.
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Affiliation(s)
- Anju Singh
- Department of Environmental Health Sciences, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD 21205, USA
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245
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Kobayashi M, Yamamoto M. Nrf2-Keap1 regulation of cellular defense mechanisms against electrophiles and reactive oxygen species. ACTA ACUST UNITED AC 2006; 46:113-40. [PMID: 16887173 DOI: 10.1016/j.advenzreg.2006.01.007] [Citation(s) in RCA: 669] [Impact Index Per Article: 35.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- Makoto Kobayashi
- JST-ERATO Environmental Response Project, Center for Tsukuba Advanced Research Alliance, Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba 305-8577, Japan
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246
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Hernandez-Montes E, Pollard SE, Vauzour D, Jofre-Montseny L, Rota C, Rimbach G, Weinberg PD, Spencer JPE. Activation of glutathione peroxidase via Nrf1 mediates genistein’s protection against oxidative endothelial cell injury. Biochem Biophys Res Commun 2006; 346:851-9. [PMID: 16780800 DOI: 10.1016/j.bbrc.2006.05.197] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2006] [Accepted: 05/27/2006] [Indexed: 01/02/2023]
Abstract
Cellular actions of isoflavones may mediate the beneficial health effects associated with high soy consumption. We have investigated protection by genistein and daidzein against oxidative stress-induced endothelial injury. Genistein but not daidzein protected endothelial cells from damage induced by oxidative stress. This protection was accompanied by decreases in intracellular glutathione levels that could be explained by the generation of glutathionyl conjugates of the oxidised genistein metabolite, 5,7,3',4'-tetrahydroxyisoflavone. Both isoflavones evoked increased protein expression of gamma-glutamylcysteine synthetase-heavy subunit (gamma-GCS-HS) and increased cytosolic accumulation and nuclear translocation of Nrf2. However, only genistein led to increases in the cytosolic accumulation and nuclear translocation of Nrf1 and the increased expression of and activity of glutathione peroxidase. These results suggest that genistein-induced protective effects depend primarily on the activation of glutathione peroxidase mediated by Nrf1 activation, and not on Nrf2 activation or increases in glutathione synthesis.
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Affiliation(s)
- Eva Hernandez-Montes
- Molecular Nutrition Group, School of Chemistry, Food Biosciences and Pharmacy, University of Reading, Reading RG6 6AP, UK
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247
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Colombo G, Gatti S, Turcatti F, Lonati C, Sordi A, Rossi G, Bonino F, Catania A. Alteration in the Transcriptional Profile of Livers from Brain-dead Organ Donors. Transplantation 2006; 82:69-79. [PMID: 16861944 DOI: 10.1097/01.tp.0000225829.07208.58] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND There is evidence that brain death causes changes in peripheral organs. Marked inflammation is found in organs collected during experimental brain death and clinical studies indicate that, despite genetic mismatch, organs obtained from living donors show improved survival over those from brain-dead donors. The aim of the present clinical research was to explore changes in the transcriptional profile of livers from brain-dead organ donors. METHODS Using the cDNA macroarray technique, we compared gene expression in liver biopsies from 21 brain-dead organ donors and in normal liver tissue obtained during resection of benign focal lesions. RESULTS Analysis of gene expression showed significant differences in the mRNA levels of 117 genes. There was reduced expression of 93 genes whereas expression of 24 genes was enhanced. Downregulated pathways included transcripts related to morphogenesis, blood coagulation, complement cascade, amine metabolism, lipid metabolism, nucleic acid metabolism, biodegradation of xenobiotics, signal transduction, and transcription. Conversely, there was induction of genes related to acute phase response, damage-related response, electron transport, and energy metabolism. CONCLUSIONS The present research demonstrates major changes in the transcriptional profile of livers from brain-dead organ donors. The presence of both down- and upregulated gene families suggests that the alteration in transcriptional profile is not a consequence of death-associated organ failure, but rather, an active change in regulatory mechanisms.
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Affiliation(s)
- Gualtiero Colombo
- Center for Preclinical Investigation, Fondazione Ospedale Maggiore Policlinico, Mangiagalli e Regina Elena Istituto di Ricovero e Cura a Carattere Scientifico, Milano, Italy
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248
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Zhu H, Zhang L, Itoh K, Yamamoto M, Ross D, Trush MA, Zweier JL, Li Y. Nrf2 controls bone marrow stromal cell susceptibility to oxidative and electrophilic stress. Free Radic Biol Med 2006; 41:132-43. [PMID: 16781461 DOI: 10.1016/j.freeradbiomed.2006.03.020] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2006] [Revised: 03/23/2006] [Accepted: 03/27/2006] [Indexed: 11/30/2022]
Abstract
Understanding the molecular pathway(s) controlling the expression of stromal cellular antioxidants and phase 2 enzymes is of importance for developing strategies to protect against bone marrow toxicity induced by oxidants and electrophiles. Accordingly, this study was undertaken to determine the role of the nuclear factor E2-related factor 2 (Nrf2) in regulation of both constitutive and chemoprotectant-inducible expression of antioxidants and phase 2 enzymes in mouse bone marrow stromal cells. The constitutive expression of a series of antioxidants and phase 2 enzymes was significantly lower in stromal cells derived from Nrf2 knockout (Nrf2(-/-)) mice than those from wild-type littermates (Nrf2(+/+)). Incubation of Nrf2(+/+) stromal cells with 3H-1,2-dithiole-3-thione (D3T) led to a significant induction of various antioxidants and phase 2 enzymes. The inducibility of the above cellular defenses by D3T was abolished in Nrf2(-/-) cells. As compared to wild-type cells, Nrf2(-/-) cells were much more susceptible to cytotoxicity induced by reactive oxygen or nitrogen species, 4-hydroxy-2-nonenal, 1,4-hydroquinone, or 1,4-benzoquinone. Upregulation of the antioxidants and phase 2 enzymes by D3T in Nrf2(+/+) stromal cells resulted in increased resistance to the above oxidant- and electrophile-induced cytotoxicity, whereas D3T treatment of Nrf2(-/-) cells only provided a marginal cytoprotection. Taken together, this study demonstrates that Nrf2 is crucial in controlling the expression of bone marrow stromal antioxidants and phase 2 enzymes as well as the susceptibility of these cells to oxidative and electrophilic stress.
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Affiliation(s)
- Hong Zhu
- Davis Heart and Lung Research Institute and Department of Internal Medicine, The Ohio State University College of Medicine and Public Health, Room 012C, 473 West 12th Avenue, Columbus, OH 43210, USA
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249
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Zhang J, Ma K, Wang H. Cyclophosphamide suppresses thioredoxin reductase in bladder tissue and its adaptive response via inductions of thioredoxin reductase and glutathione peroxidase. Chem Biol Interact 2006; 162:24-30. [PMID: 16797508 DOI: 10.1016/j.cbi.2006.04.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2006] [Revised: 04/13/2006] [Accepted: 04/21/2006] [Indexed: 10/24/2022]
Abstract
Mammalian thioredoxin reductase (TrxR) catalyzes the reduction of oxidized thioredoxin in a NADPH-dependent manner, and contains a selenocysteine residue near the C-terminus. Glutathione peroxidase (GPx) is one of the primary antioxidant enzymes that scavenge hydrogen peroxide and organic hydroperoxides. Both TrxR and GPx play an important role in protecting against oxidative stress. Cyclophosphamide (CTX), one of the most widely prescribed antineoplastic drugs, could cause cystitis. We found that 4 h after a bolus dose of CTX (30, 90, 150, 300 and 450 mg/kg) were administrated intraperitoneally, TrxR activity was significantly decreased in a dose-dependent manner, by 32%, 44%, 68%, 87% and 99%, respectively, in comparison with control group. When fixing CTX dose at 150 mg/kg, TrxR activity changed over time, significantly reduced to 68% of the activity in comparison with control tissue at 2 h, and gradually recovered to normal level within 24 h. In addition, we found that GPx activity was induced significantly after 4h. The results of the present study suggest that marked suppression of TrxR activity could be involved in the mechanism of CTX-induced cystitis, bladder may have a protective system against tissue damage by CTX via upregulation of TrxR and GPx, which is an adaptive response to oxidative stress.
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Affiliation(s)
- Jinsong Zhang
- University of Science and Technology of China, Hefei 230052, PR China.
| | - Keyang Ma
- University of Science and Technology of China, Hefei 230052, PR China
| | - Huali Wang
- University of Science and Technology of China, Hefei 230052, PR China
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250
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Gupta RK, Miller KP, Babus JK, Flaws JA. Methoxychlor Inhibits Growth and Induces Atresia of Antral Follicles through an Oxidative Stress Pathway. Toxicol Sci 2006; 93:382-9. [PMID: 16807286 DOI: 10.1093/toxsci/kfl052] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The mammalian ovary contains antral follicles, which are responsible for the synthesis and secretion of hormones that regulate estrous cyclicity and fertility. The organochlorine pesticide methoxychlor (MXC) causes atresia (follicle death via apoptosis) of antral follicles, but little is known about the mechanisms by which MXC does so. Oxidative stress is known to cause apoptosis in nonreproductive and reproductive tissues. Thus, we tested the hypothesis that MXC inhibits growth and induces atresia of antral follicles through an oxidative stress pathway. To test this hypothesis, antral follicles isolated from 39-day-old CD-1 mice were cultured with vehicle control (dimethylsulfoxide [DMSO]), MXC (1-100 microg/ml), or MXC + the antioxidant N-acetyl cysteine (NAC) (0.1-10 mM). During culture, growth was monitored daily. At the end of culture, follicles were processed for quantitative real-time polymerase chain reaction of Cu/Zn superoxide dismutase (SOD1), glutathione peroxidase (GPX), and catalase (CAT) mRNA expression or for histological evaluation of atresia. The results indicate that exposure to MXC (1-100 microg/ml) inhibited growth of follicles compared to DMSO controls and that NAC (1-10 mM) blocked the ability of MXC to inhibit growth. MXC induced follicular atresia, whereas NAC (1-10 mM) blocked the ability of MXC to induce atresia. In addition, MXC reduced the expression of SOD1, GPX, and CAT, whereas NAC reduced the effects of MXC on their expression. Collectively, these data indicate MXC causes slow growth and increased atresia by inducing oxidative stress.
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Affiliation(s)
- Rupesh K Gupta
- Program in Toxicology, Department of Epidemiology and Preventive Medicine, University of Maryland School of Medicine, 660 West Redwood Street, Howard Hall 133B, Baltimore, Maryland 21201, USA
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