Activation of mouse Pi-class glutathione S-transferase gene by Nrf2 (NF-E2-related factor 2) and androgen
Activation of mouse Pi-class glutathione S-transferase gene by Nrf2 (NF-E2-related factor 2) and androgen
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DOI：
10.1042/bj20011756
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发表时间：
2002-06-01
影响因子：
4.1
通讯作者：
Sakai, M
中科院分区：
文献类型：
--
作者：
Ikeda, H;Serria, MS;Sakai, M
Pi 类谷胱甘肽 S-转移酶 (GST) 在异生素解毒、致癌和耐药性中发挥着关键作用。这些基因在药物诱导和致癌过程中的调节机制尚未阐明。最近，Nrf2（NF-E2 相关因子 2；bZip 型转录因子）敲除小鼠被证明药物对 Pi 类 GST 基因的诱导受损。已知小鼠Pi类GST基因GST-P1主要在雄性肝脏中表达，并受雄激素调节。为了确定Nrf2和雄激素受体是否直接调节GST-P1，我们分析了这些因素激活该基因的分子机制。在瞬时转染分析中，Nrf2 显着激活了 GST-P1 基因的启动子。凝胶迁移率变化测定和足迹分析揭示了三个 Nrf2 结合位点：一个位于近端元件，两个位于远端元件，位于帽位点的 -59、-915 和 -937 位置。 GST-P1 基因的第五个内含子包含雄激素反应区。多个雄激素受体结合位点聚集在该内含子的 500 bp 区域内。整个片段至少包含七个雄激素受体结合位点，它们共同表现出强大的雄激素依赖性增强子活性。然而，当分成每个含有两个或三个元素的小片段时，单个增强子的活性显着降低。这表明多种元素作为强雄激素反应增强剂协同作用。我们的研究结果表明，Nrf2 和雄激素受体直接结合并激活小鼠 GST-P1 基因。
The Pi-class glutathione S-transferases (GSTs) play pivotal roles in the detoxification of xenobiotics, carcinogenesis and drug resistance. The mechanisms of regulation of these genes during drug induction and carcinogenesis are yet to be elucidated. Recently, Nrf2 (NF-E2-related factor 2; a bZip-type transcription factor) knockout mice were shown to display impaired induction of Pi-class GST genes by drugs. It is known that the mouse Pi-class GST gene GST-P1 is expressed predominantly in the male liver, and is regulated by androgen. To determine whether Nrf2 and the androgen receptor regulate GST-P1 directly, we analysed the molecular mechanism of activation of this gene by these factors. The promoter of the GST-P1 gene was activated markedly by Nrf2 in transient transfection analyses. Gel mobility shift assay and footprinting analyses revealed three Nrf2 binding sites: one at the proximal and two at distal elements, located at positions -59, -915 and -937 from the cap site. The fifth intron of the GST-P1 gene contains the androgen-responsive region. Multiple androgen receptor binding sites are clustered within a 500 bp region of this intron. The whole fragment contains a minimum of seven androgen receptor binding sites, which collectively display strong androgen-dependent enhancer activity. However, on division into small fragments containing two or three elements each, individual enhancer activities were dramatically decreased. This suggests that multiple elements work synergistically as a strong androgen-responsive enhancer. Our findings indicate that Nrf2 and the androgen receptor directly bind to and activate the mouse GST-P1 gene.