Regulation of aldehyde reductase expression by STAF and CHOP
Regulation of aldehyde reductase expression by STAF and CHOP
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DOI：
10.1016/s0888-7543(03)00213-1
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发表时间：
2004-01-01
期刊：
影响因子：
4.4
通讯作者：
Gabbay, KH
中科院分区：
文献类型：
--
作者：
Barski, OA;Papusha, VZ;Gabbay, KH
醛还原酶参与活性醛的还原解毒，可以修饰细胞大分子。为了分析乙醛还原酶表达的基础调控机制，我们克隆了小鼠基因及其邻近的调控区，并将其与人类基因进行了比较。鼠酶表现出与人类酶相似的底物专一性，但催化效率提高了2倍。与老鼠基因不同，人醛还原酶基因有两个选择性剪接的转录本。57bp的片段足以满足25%的人类启动子活性，并由两个元件组成。3‘端元件结合Sp1家族的转录因子。凝胶漂移分析、染色质免疫沉淀和缺失/突变分析表明，硒半胱氨酸tRNA转录激活因子(STAF)与5‘端元件结合，并驱动鼠和人醛还原酶的结构性表达。因此，乙醛还原酶成为STAF调控的第四个蛋白编码基因。人而不是小鼠的启动子也与C/EBP同源蛋白(CHOP)结合，CHOP与STAF竞争相同的结合部位。将人启动子导入乙氧基喹处理的小鼠3T3细胞，启动子活性增加3.5倍，用人醛还原酶启动子的5‘端探针进行凝胶位移时，出现CHOP-C/EBP条带。在类似的小鼠启动子的转基因研究中，诱导作用减弱。人类启动子中CHOP结合位点的突变取消了CHOP结合，并显著降低了乙氧基喹的诱导，这表明CHOP介导了人类对抗氧化剂的刺激表达。人类启动子的这种细微差异表明启动子进一步进化为对外源压力和/或毒素的反应。(C)2003 Elsevier Inc.保留所有权利。
Aldehyde reductase is involved in the reductive detoxification of reactive aldehydes that can modify cellular macromolecules. To analyze the mechanism of basal regulation of aldehyde reductase expression, we cloned the murine gene and adjacent regulatory region and compared it to the human gene. The mouse enzyme exhibits substrate specificity similar to that of the human enzyme, but with a 2-fold higher catalytic efficiency. In contrast to the mouse gene, the human aldehyde reductase gene has two alternatively spliced transcripts. A fragment of 57 bp is sufficient for 25% of human promoter activity and consists of two elements. The 3' element binds transcription factors of the Sp1 family. Gel-shift assays and chromatin immunoprecipitation as well as deletion/mutation analysis reveal that selenocysteine tRNA transcription activating factor (STAF) binds to the 5' element and drives constitutive expression of both mouse and human aldehyde reductase. Aldehyde reductase thus becomes the fourth protein-encoding gene regulated by STAF. The human, but not the mouse, promoter also binds C/EBP homologous protein (CHOP), which competes with STAF for the same binding site. Transfection of the human promoter into ethoxyquin-treated mouse 3T3 cells induces a 3.5-fold increase in promoter activity and a CHOP-C/EBP band appears on gel shifts performed with the 5' probe from the human aldehyde reductase promoter. Induction is attenuated in similar transfection studies of the mouse promoter. Mutation of the CHOP-binding site in the human promoter abolishes CHOP binding and significantly reduces ethoxyquin induction, suggesting that CHOP mediates stimulated expression in response to antioxidants in the human. This subtle difference in the human promoter suggests a further evolution of the promoter toward responsiveness to exogenous stress and/or toxins. (C) 2003 Elsevier Inc. All rights reserved.