STUDIES ON FUNCTIONS OF THIOREDOXIN REDUCTASE IN DETOXIFICATION OF HEAVY METALS

硫氧还蛋白还原酶重金属解毒作用的研究

• 批准号: 16590093
• 负责人: HARA Shuntaro
• 金额: $ 2.24万
• 依托单位: SHOWA UNIVERSITY (2005)Kitasato University (2004)
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2004
• 资助国家: 日本
• 起止时间: 2004 至 2005
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-16590093/
• 关键词: THIOREDOXIN REDUCTASE; HEAVY METALS; CADMIUM; NF-E2-RELATED FACTOR-2; ANTIOXIDATIVE ENZYME; siRNA; ヒ素; 低酸素応答性転写因子; 貴金属; 血管内皮細胞; 遺伝子発現; Nrf2

The mammalian thioredoxin reductase (TrxR) is a selenocysteine-containing flavoprotein that regulates the thioredoxin system, one of the major systems that maintain the intracellular redox balance. To date, three TrxR isozymes, TrxR1, TrxR2 and TrxR3, have been identified. We previously reported that TrxR1 was induced by heavy metals such as cadmium (Cd) and arsenite (As). In this study, the functions of TrxR1 in detoxification of heavy metals were investigated as follows :(1)Transcriptional regulation of Cd-induced TrxR1 expression-Treatment of bovine arterial endothelial cells with Cd 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) (nucleotide -62 to -48) in this region abolished the response to Cd. Overexpression of NF-E2-related factor-2 (Nrf2) augmented the TrxR1 promoter activity. These results indicated that Cd-induced TrxR1 gene expression is mediated by the activation of Nrf2 and its binding to ARE in the TrxR1 gene promoter. We further found that in addition to Cd, the activators of Nrf2, such as diethyl maleate (DEM) and As, induced both TrxR1 and Trx gene expression. Nrf2 might play an important role in the regulation of the cellular Trx system consisting of Trx and TrxR.(2)Involvement of TrxR1 in cellular defense against heavy metals-We silenced the expression of TrxR1 in HeLa cells by using short-interfering RNA and found that the gene silencing of TrxR1 had a dual effect on Cd- and As-induced celldeath, depending on the concentration of heavy metals. The TrxR1 silencing increased the sensitivity toward a low dose of heavy metals but decreased the sensitivity toward a high dose of heavy metals. These results suggested that TrxR1 might play an important role in the cellular defense system against heavy metals in two ways.

哺乳动物硫氧还蛋白还原酶 (TrxR) 是一种含硒代半胱氨酸的黄素蛋白，可调节硫氧还蛋白系统，这是维持细胞内氧化还原平衡的主要系统之一。迄今为止，已鉴定出三种 TrxR 同工酶：TrxR1、TrxR2 和 TrxR3。我们之前报道过 TrxR1 是由镉 (Cd) 和亚砷酸盐 (As) 等重金属诱导的。本研究对TrxR1在重金属解毒中的功能进行了如下研究：(1)Cd诱导TrxR1表达的转录调控——Cd处理牛动脉内皮细胞增强了TrxR1 5'侧翼区的启动子活性。人类 TrxR1 基因（核苷酸 -1692 至 +49）。该区域抗氧化反应元件（ARE）（核苷酸-62至-48）的缺失和定点突变消除了对镉的反应。 NF-E2 相关因子 2 (Nrf2) 的过表达增强了 TrxR1 启动子活性。这些结果表明，Cd 诱导的 TrxR1 基因表达是通过 Nrf2 的激活及其与 TrxR1 基因启动子中的 ARE 的结合介导的。我们进一步发现，除了Cd之外，Nrf2的激活剂，例如马来酸二乙酯（DEM）和As，也诱导TrxR1和Trx基因表达。 Nrf2可能在调节由Trx和TrxR组成的细胞Trx系统中发挥重要作用。(2)TrxR1参与细胞对重金属的防御——我们利用短干扰RNA沉默HeLa细胞中TrxR1的表达，发现TrxR1 基因沉默对 Cd 和 As 诱导的细胞死亡具有双重影响，具体取决于重金属的浓度。 TrxR1沉默增加了对低剂量重金属的敏感性，但降低了对高剂量重金属的敏感性。这些结果表明，TrxR1 可能通过两种方式在针对重金属的细胞防御系统中发挥重要作用。

项目成果

Short-interfering RNA-mediated Silencing of Thioredoxin Reductase 1 Alters the Sensitivity of HeLa Cells toward Cadmium

短干扰 RNA 介导的硫氧还蛋白还原酶 1 沉默改变了 HeLa 细胞对镉的敏感性

• 发表时间: 2006
• 期刊: Biological and Pharmaceutical Bulletin 29・3
• 作者: C.Cuiping;R.Tanaka;Y.Okuda;N.Ikota;H.Yamamoto;S.Urano;T.Ozawa;K.Anzai;西本 理恵 ほか
• 通讯作者: 西本 理恵 ほか

Transcriptional Regulation of Thioredoxin Reductase 1 Expression by Cadmium in Vascular Endothelial Cells

血管内皮细胞中镉对硫氧还蛋白还原酶 1 表达的转录调节

• 发表时间: 2005
• 期刊: Journal of Cellular Physiology 203・3
• 作者: Hashimoto Y;Kaneko Y;Tsukamoto E;Frankowski H;Kouyama K;Kita Y;Niikura T;Aiso S;Bredesen DE;Matsuoka M;Nishimoto I;Kitamura et al.分担(R.C.Gupta編集);Tetsushi Watanabe;櫻井貴子ほか
• 通讯作者: 櫻井貴子ほか