Rapid induction of cell death by selenium-compromised thioredoxin reductase 1 but not by the fully active enzyme containing selenocysteine
Rapid induction of cell death by selenium-compromised thioredoxin reductase 1 but not by the fully active enzyme containing selenocysteine
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DOI：
10.1074/jbc.m210733200
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发表时间：
2003-05-02
影响因子：
4.8
通讯作者：
Arnér, ESJ
中科院分区：
文献类型：
--
作者：
Anestål, K;Arnér, ESJ
哺乳动物硫氧还蛋白还原酶是硒蛋白。对于天然催化活性，这些酶利用C-末端-Gly-Cys-Sec-Gly-COOH序列（其中Sec是硒代半胱氨酸）形成氧化还原活性硒基硫化物/硒醇硫醇基序。一系列细胞系统依赖于硫氧还蛋白还原酶及其主要蛋白质底物硫氧还蛋白，包括凋亡信号调节激酶1、过氧化物酶、甲硫氨酸亚砜还原酶和几种转录因子，或受其调节。此外，细胞溶质硫氧还蛋白还原酶1（TrxR 1）被各种亲电抗癌化合物抑制。因此，TrxR 1通常被认为促进细胞活力。然而，最近的几项研究表明，TrxR 1可能会促进细胞凋亡，该酶被鉴定为GRIM-12（与类维生素A干扰素诱导的死亡率相关的基因12）。用GRIM-12/TrxR 1瞬时转染也显示直接诱导细胞死亡。为了进一步分析这种影响，我们在这里采用脂质介导的重组TrxR 1制剂进入人A549细胞，从而绕过硒蛋白翻译，以促进评估蛋白质相关的影响细胞活力。我们发现，缺硒TrxR 1，具有两个氨基酸截短的C-末端-Gly-Cys-COOH基序，迅速诱导细胞死亡（4小时后38 +/- 29%凋亡细胞;与对照组相比p < 0.005）。细胞死亡诱导也促进硒受损TrxR 1衍生的顺式二氨基二氯铂（H）（顺铂）或二硝基苯基部分，但不是由结构相关的非硒蛋白谷胱甘肽还原酶。相反，TrxR 1与完整的硒代半胱氨酸不能促进细胞死亡。硒受损形式的TrxR 1的直接细胞效应对于硒缺乏的病理生理学以及针对该酶的硒代半胱氨酸部分的抗增殖药物的功效可能是重要的。
Mammalian thioredoxin reductases are selenoproteins. For native catalytic activity, these enzymes utilize a C-terminal -Gly-Cys-Sec-Gly-COOH sequence (where Sec is selenocysteine) forming a redox active selenenyl-sulfide/selenolthiol motif. A range of cellular systems depend upon or are regulated by thioredoxin reductase and its major protein substrate thioredoxin, including apoptosis signal-regulating kinase 1, peroxiredoxins, methionine sulfoxide reductase, and several transcription factors. Cytosolic thioredoxin reductase 1 (TrxR1) is moreover inhibited by various electrophilic anticancer compounds. TrxR1 is hence generally considered to promote cell viability. However, several recent studies have suggested that TrxR1 may promote apoptosis, and the enzyme was identified as GRIM-12 (gene associated with retinoid interferon-induced mortality 12). Transient transfection with GRIM-12/TrxR1 was also shown to directly, induce cell death. To further analyze such effects, we have here employed lipid-mediated delivery of recombinant TrxR1 preparations into human A549 cells, thereby bypassing selenoprotein translation to facilitate assessment of the protein-related effects on cell viability. We found that selenium-deficient TrxR1, having a two-amino acid-truncated C-terminal -Gly-Cys-COOH motif, rapidly induced cell death (38 +/- 29% apoptotic cells after 4 h; p < 0.005 compared with controls). Cell death induction was also promoted by selenium-compromised TrxR1 derivatized with either cis-diam-minedichloroplatinum (H) (cisplatin) or dinitrophenyl moieties but not by the structurally related non-selenoprotein glutathione reductase. In contrast, TrxR1 with intact selenocysteine could not promote cell death. The direct cellular effects of selenium-compromised forms of TrxR1 may be important for the pathophysiology of selenium deficiency as well as for the efficacy of antipro-liferative drugs targeting the selenocysteine moiety of this enzyme.