Loss of microRNA 122 expression in patients with hepatitis B enhances hepatitis B virus replication through cyclin G1-modulated P53 activity
Loss of microRNA 122 expression in patients with hepatitis B enhances hepatitis B virus replication through cyclin G1-modulated P53 activity
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DOI：
10.1002/hep.24809
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发表时间：
2012-03-01
期刊：
影响因子：
13.5
通讯作者：
Meng, Songdong
中科院分区：
文献类型：
--
作者：
Wang, Saifeng;Qiu, Lipeng;Meng, Songdong
乙型肝炎病毒（HBV）导致全球约3.5亿人慢性感染。鉴于最丰富的肝脏特异性microRNA miR-122在肝功能和肝脏病理中的重要作用，我们在这里研究了miR-122在调节HBV复制中的潜在作用和机制。我们发现，与健康对照组相比，HBV感染患者肝脏中miR-122的表达显著下调，miR-122水平与肝内病毒载量和肝坏死炎症呈负相关。内源性miR-122被其反义抑制剂耗尽导致HBV复制增强，而转染模拟物或其表达载体过表达miR-122抑制病毒产生。接下来，我们从参与HBV复制调控的多个候选靶基因中确定了cyclin G1作为miR-122靶点。过表达和敲低研究均表明，在HBV转染的细胞中，cyclin G1调节病毒复制。我们还观察到，在hbv感染患者中，细胞周期蛋白G1表达上调，并且细胞周期蛋白G1水平与肝组织中miR-122的表达呈负相关。通过共免疫沉淀、荧光素酶报告系统和电泳迁移转移实验，我们进一步证明了细胞周期蛋白G1特异性地与p53相互作用，这种相互作用阻断了p53与HBV增强元件的特异性结合，同时取消了p53介导的HBV转录抑制。最后，我们发现miR-122在p53野生型细胞中抑制HBV复制，但在零等基因细胞中没有。结论：miR-122下调其靶细胞周期蛋白G1，从而中断细胞周期蛋白G1与p53的相互作用，取消p53介导的对HBV复制的抑制。我们的研究表明，HBV感染诱导的miR-122下调可以影响HBV复制，并可能有助于病毒的持续存在和致癌。(肝脏病学2012;)
Hepatitis B virus (HBV) causes chronic infection in about 350 million people worldwide. Given the important role of the most abundant liver-specific microRNA, miR-122, in hepatic function and liver pathology, here we investigated the potential role and mechanism of miR-122 in regulating HBV replication. We found that miR-122 expression in liver was significantly down-regulated in patients with HBV infection compared with healthy controls, and the miR-122 levels were negatively correlated with intrahepatic viral load and hepatic necroinflammation. The depletion of endogenous miR-122 by its antisense inhibitor led to enhanced HBV replication, whereas overexpression of miR-122 by transfection of mimic or its expression vector inhibited viral production. We next identified cyclin G1 as an miR-122 target from multiple candidate target genes that are involved in the regulation of HBV replication. Overexpression and knockdown studies both showed that cyclin G1 regulated viral replication in HBV transfected cells. We also observed that cyclin G1 expression was up-regulated in HBV-infected patients, and cyclin G1 levels were inversely associated with miR-122 expression in liver tissues. Using coimmunoprecipitation, a luciferase reporter system, and electrophoretic mobility shift assay, we further demonstrated that cyclin G1 specifically interacted with p53, and this interaction blocked the specific binding of p53 to HBV enhancer elements and simultaneously abrogated p53-mediated inhibition of HBV transcription. Finally, we show that miR-122 suppressed HBV replication in p53 wildtype cells but not in null isogenic cells. Conclusion: miR-122 down-regulates its target cyclin G1, and thus interrupts the interaction between cyclin G1 and p53 and abrogates p53-mediated inhibition of HBV replication. Our work shows that miR-122 down-regulation induced by HBV infection can impact HBV replication and possibly contribute to viral persistence and carcinogenesis. (HEPATOLOGY 2012;)