Transcriptional regulation of thioredoxin reductase 1 expression by cadmium in vascular endothelial cells: Role of NF-E2-related factor-2
Transcriptional regulation of thioredoxin reductase 1 expression by cadmium in vascular endothelial cells: Role of NF-E2-related factor-2
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DOI：
10.1002/jcp.20246
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发表时间：
2005-06-01
影响因子：
5.6
通讯作者：
Hara, S
中科院分区：
文献类型：
--
作者：
Sakurai, A;Nishimoto, M;Hara, S
硫氧还蛋白还原酶(TrxR)是一种硒蛋白，催化硫氧还蛋白活性部位二硫键(Trx)的还原，调节细胞的氧化还原状态。在本研究中，我们发现牛动脉内皮细胞(BAEC)三种TrxR同工酶之一的TrxR I受镉和肿瘤坏死因子α(TNFα)的诱导，并探讨了镉诱导TrxR1表达的机制。我们发现，与肿瘤坏死因子α不同，镉增强了人类TrxR1基因5‘侧翼区(核苷酸-1692至+49)的启动子活性。该区域的抗氧化反应元件(ARE)(核苷酸-62至-48)的缺失和定点突变消除了对镉的反应。过表达核因子-E2相关因子-2(Nrt2)可增强TrxR1启动子的活性。相反，Nrf2显性负性突变体的过表达通过ARE抑制了镉诱导的TrxR1启动子的激活。染色质免疫沉淀(ChIP)分析表明，抗Nrf2抗体从染色质中沉淀出来。这些结果表明，镉诱导的TrxR1基因表达是由转录因子Nrf2的激活及其与TrxR1基因启动子中ARE的结合所介导的。我们进一步发现，除了镉，Nrf2的激活剂，如马来酸二乙酯(DEM)和亚砷酸盐，也能诱导BAEC中TrxR1和Trx基因的表达。Nrf2可能在由Trx和TrxR组成的细胞内Trx系统的调节中发挥重要作用。(C)2004年Wiley-Liss公司
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 TrxR I, one of the three TrxR isozymes, was induced by cadmium as well as tumor necrosis factor alpha, (TNF alpha) in bovine arterial endothelial cells (BAEC), and investigated the mechanism of cadmium-induced TrxR1 expression. We here showed that cadmium, differently from TNF alpha, enhanced the promoter activity of the 5'-flanking region of the 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 (Nrt2) 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. (c) 2004 Wiley-Liss, Inc.