银杏内酯B通过激活孕烷X受体诱导CYP3A4的表达

Ginkgolide B induces CYP3A4 expression through activation of human pregnane X receptor

目的研究银杏内酯B(ginkgolide B)对CYP3A4的诱导作用,进一步验证是否通过激活孕烷X受体实现对CYP3A4 mRNA和蛋白水平的诱导表达。方法用不同浓度银杏内酯B处理LS174T细胞,通过Q-PCR法检测CYP3A4 mRNA表达变化,进一步利用本实验室构建的PXRCYP3A4稳定转染HepG2工程细胞株,结合荧光素酶报告基因技术,显示检测银杏内酯B对PXR的转录激活活性的影响。蛋白质免疫印迹法检测CYP3A4蛋白水平表达的变化;利用siRNA技术敲低PXR的mRNA表达,检测在PXR低表达的条件下银杏内酯B对CYP3A4 mRNA和蛋白水平表达影响。结果银杏内酯B可以浓度依赖性的使CYP3A4基因及蛋白表达水平上调,报告基因结果显示,银杏内酯B能够浓度依赖性的增强PXR的转录激活活性,在PXR低表达的条件下,银杏内酯B对CYP3A4诱导作用明显低于正常表达组PXR。结论以上表明银杏内酯B通过激活PXR受体,促进其转录激活活性进而诱导CYP3A4表达上调,同时对PXR自身的表达无明显影响。

Aim To study the induction effect of Ginkgolide B on CYP3A4,and further verify the role of pregnane X receptor in CYP3 A4 induction expres-sion. Methods With different concentrations of Ginkgolide B treatment on LS174T cells,the CYP3A4 mRNA expression was detected by Q-PCR assay,fur-ther PXR-CYP3 A4 stable translation HepG2 cell lines＆amp;nbsp;were used to test the effect of Ginkgolide B on activity of PXR by reporter gene screening assay.CYP3A4 protein expression was detected by Western blot.PXR was knocked down with transfected with siRNA, CYP3 A4 mRNA and protein were detected in the con-dition of PXR low expression.Results The results revealed that the level of CYP 3 A 4 gene and protein＆amp;nbsp;expression were significantly increased by Ginkgolide B,and there was no induction effect on PXR.Reporter gene screening showed that Ginkgolide B could en-hance the transcriptional activity of PXR in a concen-tration-dependent manner.Under conditions of low ex-pression of PXR ,Ginkgolide B could also increase ex-pression of CYP3A4,but the induction folds were low-er than those of normal PXR group.Conclusion Ginkgolide B can signicantly up-regulate CYP3 A4 ex-pression via the PXR-CYP3 A4 pathway,and it has no effects on PXR gene expression.