Inhibition of ERK and p38 MAP kinases inhibits binding of Nrf2 and induction of GCS genes.
Inhibition of ERK and p38 MAP kinases inhibits binding of Nrf2 and induction of GCS genes.
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DOI：
10.1006/bbrc.2000.3830
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发表时间：
2000-11
影响因子：
3.1
通讯作者：
Laurie M. Zipper;R. Mulcahy
中科院分区：
文献类型：
--
作者：
Laurie M. Zipper;R. Mulcahy
编码人γ-谷氨酰半胱氨酸合成酶（γ GCS）的催化亚基（GCS（h））和调节亚基（GCS（l））的基因通过亲电反应元件（EpRE）响应外源性物质而上调，所述γ-谷氨酰半胱氨酸合成酶催化谷胱甘肽合成中的限速步骤。HepG 2细胞暴露于GCS诱导剂吡咯烷二硫代氨基甲酸酯（PDTC）导致ERK和p38 MAP激酶活化。分别通过PD 98059或SB 202190抑制ERK或p38激酶导致GCS基因诱导减少约50%，而同时抑制则完全消除诱导。GCS表达的诱导与Nrf 2和JunD与GCS EpRE结合的增加相关。用MAPK抑制剂预处理显著降低了两种转录因子的结合。这些研究表明，ERK和p38的GCS亚基基因的转录上调PDTC处理后。此外，超位移分析表明，Nrf 2和JunD与EpRE的结合是ERK和p38磷酸化事件的下游结果。
Genes encoding the catalytic (GCS(h)) and regulatory (GCS(l)) subunits of human gamma-glutamylcysteine synthetase (gammaGCS), which catalyzes the rate limiting step in glutathione synthesis, are up-regulated in response to xenobiotics through Electrophile Response Elements (EpREs). Exposure of HepG2 cells to the GCS-inducing agent, Pyrrolidine dithiocarbamate (PDTC), results in ERK and p38 MAP kinase activation. Inhibition of ERK or p38 kinases by PD98059 or SB202190, respectively, results in approximately 50% reduction in GCS gene induction, while simultaneous inhibition completely eliminates induction. Induction of GCS expression is associated with an increase in Nrf2 and JunD binding to GCS EpREs. Pretreatment with the MAPK inhibitors significantly reduces binding of both transcription factors. These studies indicate that ERK and p38 contribute to the transcriptional up-regulation of the GCS subunit genes following PDTC treatment. Furthermore, supershift analyses suggest that binding of Nrf2 and JunD to the EpRE is a downstream consequence of ERK and p38 phosphorylation events.