HNF4α-AS1/HNF4α-PXR通路参与异源物质暴露后细胞色素P450酶系稳态调控的机制研究

细胞色素P450酶系（CYPs）稳态的变化是引起药物相互作用和毒性的重要原因。但异源物质暴露后CYPs表达恢复稳态的调控机制并不清楚。我们前期研究发现肝脏转录因子HNF4α的反义lncRNA HNF4α-AS1在利福平暴露后期被快速诱导表达，并抑制利福平对Huh7细胞HNF4α、PXR和CYPs的诱导作用，而沉默HNF4α-AS1可增加HNF4α及组蛋白修饰H3K4me3在CYP3A4基因启动子区的富集并激活CYP3A4的表达。由此提出假说：HNF4α-AS1通过负调控作用影响HNF4α-PXR通路参与调控异源物质暴露后CYPs稳态的恢复。本课题将阐明HNF4α-AS1/HNF4α-PXR通路参与利福平诱导CYPs表达后稳态恢复的调控机制，并结合PXR/CYP3A4介导的利福平/利托那韦肝毒性模型求证以上科学假说，以期发现预测CYPs介导的药物代谢和肝毒性的关键靶点。

The induction of cytochrome P450 enzymes (CYPs) by xenobiotics usually disrupts the CYPs homeostasis, which is a curial cause of drug-drug interactions and drug toxicity. However, the molecular mechanism that controlling the CYPs homeostasis after xenobiotics exposure remains unknown. Our preliminary data have shown that HNF4α antisense RNA 1 (HNF4α-AS1), an antisense lncRNA of HNF4α, was rapidly induced at the late stage of rifampin exposure. Moreover, HNF4α-AS1 could repress the induction of HNF4α, PXR, and CYPs by rifampin in Huh7 cells. Knockdown of HNF4α-AS1 led to elevated enrichment levels of HNF4α and H3K4me3 in the promoter of CYP3A4 gene and higher expression of CYP3A4. Accordingly, we hypothesize that HNF4α-AS1 plays a key role in maintaining the CYPs homeostasis after xenobiotic exposure via a negative feedback mechanism affecting HNF4α-PXR pathway. In this study, the molecular mechanism of HNF4α-AS1/HNF4α-PXR pathway-mediated CYPs homeostasis after rifampin exposure will be studied. And the hypothesis will be confirmed in PXR/CYP3A4-mediated rifampin/ritonavir hepatotoxicity by using in vitro and in vivo models. The present study will provide evidence for discovering potential targets that could predict CYPs-mediated drug metabolism and liver toxicity.