title: Transcriptional regulation of thioredoxin reductase 1 expression by cadmium in vascular endothelial cells: role of NF-E2-related factor-2.
abstract: Thioredoxin reductase (TrxR) is a selenoprotein that catalyzes the reduction of the active site disulfide of thioredoxin (Trx), which regulates the redox status of the cells. In the present study, we found that TrxR1, one of the three TrxR isozymes, was induced by cadmium as well as tumor necrosis factor alpha (TNFalpha) in bovine arterial endothelial cells (BAEC), and investigated the mechanism of cadmium-induced TrxR1 expression. We here showed that cadmium, differently from TNFalpha, enhanced the promoter activity of the 5'-flanking region of human TrxR1 gene (nucleotides -1692 to +49). Deletion and site-directed mutation of antioxidant responsive element (ARE) (nucleotides -62 to -48) in this region abolished the response to cadmium. Overexpression of NF-E2-related factor-2 (Nrf2) augmented the TrxR1 promoter activity. In contrast, overexpression of the dominant negative mutant of Nrf2 suppressed cadmium-induced activation of TrxR1 promoter through the ARE. Chromatin immunoprecipitation (ChIP) assays showed that anti-Nrf2 antibody precipitated ARE from the chromatin of the cadmium-treated cells. These results indicated that cadmium-induced TrxR1 gene expression is mediated by the activation of Nrf2 transcription factor and its binding to ARE in the TrxR1 gene promoter. We further found that in addition to cadmium, the activators of Nrf2, such as diethyl maleate (DEM) and arsenite, induced both TrxR1 and Trx gene expression in BAEC. Nrf2 might play an important role in the regulation of the cellular Trx system consisting of Trx and TrxR.
authors.affiliation: Department of Public Health and Molecular Toxicology, School of Pharmaceutical Sciences, Kitasato University, Tokyo, Japan.
authors.forename: Atsuko
authors.initials: A
authors.lastname: Sakurai
authors.forename: Michie
authors.initials: M
authors.lastname: Nishimoto
authors.forename: Seiichiro
authors.initials: S
authors.lastname: Himeno
authors.forename: Nobumasa
authors.initials: N
authors.lastname: Imura
authors.forename: Masafumi
authors.initials: M
authors.lastname: Tsujimoto
authors.forename: Manabu
authors.initials: M
authors.lastname: Kunimoto
authors.forename: Shuntaro
authors.initials: S
authors.lastname: Hara
mesh_terms: D024506:5' Flanking Region / Q000187:drug effects / Q000235:genetics; D000818:Animals; D018053:Arsenites / Q000494:pharmacology; D002104:Cadmium / Q000494:pharmacology*; D002417:Cattle; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000187:drug effects / Q000235:genetics; D005809:Genes, Regulator / Q000187:drug effects / Q000235:genetics*; D006801:Humans; D008293:Malates / Q000494:pharmacology; D016297:Mutagenesis, Site-Directed / Q000235:genetics; D009154:Mutation / Q000235:genetics; D051267:NF-E2-Related Factor 2; D011401:Promoter Regions, Genetic / Q000187:drug effects / Q000235:genetics; D054481:Thioredoxin Reductase 1; D013880:Thioredoxin-Disulfide Reductase / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D015533:Transcriptional Activation / Q000187:drug effects / Q000235:genetics; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D015854:Up-Regulation / Q000187:drug effects / Q000235:genetics
chemical_list: D018053:Arsenites; D004268:DNA-Binding Proteins; D008293:Malates; D051267:NF-E2-Related Factor 2; C495635:NFE2L2 protein, human; D015534:Trans-Activators; D014409:Tumor Necrosis Factor-alpha; D002104:Cadmium; C058705:diethyl malate; C516124:TXNRD1 protein, human; D054481:Thioredoxin Reductase 1; D013880:Thioredoxin-Disulfide Reductase; C015001:arsenite