Studies on Induction and Functions of Thioredoxin Reductase in Stress Responses

硫氧还蛋白还原酶应激反应的诱导及功能研究

• 批准号: 13672345
• 负责人: HARA Shuntaro
• 金额: $ 2.24万
• 依托单位: Kitasato University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2001
• 资助国家: 日本
• 起止时间: 2001 至 2002
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-13672345/
• 关键词: Thiorecoxin reductase; Transcription factor; Redox; NF-κB; Stress response; Cadmium; レドックス制御; ストレス応答

Thioredoxin reductase (TrxR) is an antioxidant enzyme that has an ability to reduce thioredoxin (Trx). It is indicated that Trx plays an important role in stress responses, but the role of TrxR in the stress responses remains unclear. To date, three TrxR isozymes, TrxR1, TrxR2 and Trx3, have been identified. Among these isozymes, only TrxR1 is induced by various kinds of stresses. In this study, in order to reveal the role of TrxR in stress responses, the mechanism of induction and the functions of TrxR1 were studied as follows:(1) Regulation of stress-induced TrxR1 expression - Exposure of bovine arterial endothelial cells (BAEC) to TNFα, PMA+A23187, or Cd upregulated the expression of TrxR1 but neither TrxR2 nor TrxR3. First, role of the promoter region in the huma TrxR1 gene was evaluated by the transient transfection of luciferase reporter vectors into BAEC. Both PMA+A23187 and Cd elevated luciferase activity via the region between-646 and 46 bp. On the other hand, TNFα did not affect the luciferase activity, but the mRNA decay experiments using actinomycin D showed that TNFα stabilized TrxR1 mRNA. These results indicate that both transcriptional activation and posttranscriptional mRNA stabilization may contribute to the stress-induced expression of TrxR1, and that the contributive mechanisms may vary with kinds of stresses.(2) Role of TrxR1 in stress-responsive transcription factor-mediated gene expression - Reporter gene analysis revealed that the overexpression of TrxR1 enhanced AP-1- and NF-κB-dependent gene expression. The catalytic selenocysteine residue of TrxR1, which is essential for reducing Trx, was required for this activation, and aurothiomalate, an inhibitor of TrxR, suppressed this activation. These results suggest that TrxR1 may act as a positive regulator of stress-responsive transcription factors, AP-1 and NF-κB via its ability to reduce Trx.

硫氧还蛋白还原（TRXR）是一种具有降低硫氧还蛋白（TRX）的能力的抗氧化剂。据表明，TRX在压力反应中起重要作用，但是TRXR在应力反应中的作用尚不清楚。迄今为止，已经鉴定出三个TRXR同工酶TRXR1，TRXR2和TRX3。在这些同工酶中，只有TRXR1由各种应力诱导。在这项研究中，为了揭示TRXR在压力反应中的作用，对诱导机制和TRXR1的功能进行了以下研究：（1）调节应力诱导的TRXR1表达 - 牛动脉内皮细胞（BAEC）对TNFα，PMA+A23187或CD升级的TRRX nof 3 nove 3 nove 3 nove 3 nouptr 3 nof trrr2 nof trrrr 2 nofe nof trrr2。首先，通过将荧光素酶报道载体的瞬时转染到BAEC中评估启动子区域在人TRXR1基因中的作用。 PMA+A23187和CD均通过646至46 bp之间的区域升高荧光素酶活性。另一方面，TNFα不影响荧光素酶活性，但是使用放线肌蛋白D的mRNA衰变实验表明TNFα稳定了TRXR1 mRNA。 These results indicate that both transcriptional activation and posttranscriptional mRNA stabilization may contribute to the stress-induced expression of TrxR1, and that the contributive mechanisms may vary with kinds of stresses.(2) Role of TrxR1 in stress-responsive transcription factor-mediated gene expression - Reporter gene analysis revealed that the overexpression of TrxR1 enhanced AP-1- and NF-κB-dependent gene expression. TRXR1的催化硒代半胱氨酸保留，对于减少TRX至关重要，需要进行这种激活，而TRXR的抑制剂则抑制了这种激活。这些结果表明，TRXR1可以通过减少TRX的能力来充当应力反应转录因子AP-1和NF-κB的正调节剂。