let-7f及家族成员参与调控乙型肝炎病毒复制的研究

microRNAs (miRNA) are a class of non-coding small RNA that plays an important role in the interaction between virus and the host. Although there have been several reports on the regulation of hepatitis B virus (HBV) replication by miRNAs, little evidence has been presented on the association between these miRNAs' expression levels and response and prognosis to antiviral therapy in chronic HBV patients. Our previous work demonstrated that an expression profile made up of 11 miRNAs are highly correlated with response to intereron therapy in chronic HBV patients, which suggests that these miRNAs are probably involved in the regulation of HBV life cycle. Preliminary experiments showed that among them, high level of let-7f was able to inhibit the replication of HBV. Based on these observations, we propose to further confirm the regulatory roles of let-7f in vivo using the HBV plasmid based tail vein injection model. Furthermore, we plan to test whether let-7f and its family members regulate HBV replication by modulating HNF3 (hepatocyte nuclear fator 3) level.In addition, we intend to perform microarrary analysis to find novel target genes of these miRNAs and examine the exact mechanism by which they regulate the HBV life cycle. The results of this project may help to deepen the understanding of the interplay between host and HBV in the process of chronic infection.

microRNA作为一类重要的非编码小RNA在病毒与宿主相互拮抗过程中起到了非常重要的作用。尽管目前已有一些miRNA调控乙肝病毒（HBV）复制的报道，但它们在慢乙肝患者的转归及疗效的相关性仍缺乏明确的证据。本项目前期工作发现由11个miRNA组成的表达谱与慢乙肝干扰素治疗的应答密切关联，提示这些miRNA可能参与了拮抗HBV的复制周期。初步结果显示在这11个miRNA中，let-7f高表达能显著抑制HBV复制。本项目在此基础上，拟在体外和小鼠尾静脉注射模型中确认let-7f调控HBV复制的现象。在作用机制方面探索let-7f及家族成员是否通过靶向肝细胞核因子3（HNF3）水平调控HBV增强子的活性。另外通过基因芯片等方法寻找入选miRNA调控的靶基因，对候选靶基因是否参与调控HBV复制并确定其具体作用环节进行深入研究。本研究的结果有助于了解HBV感染慢性化过程中与宿主的相互拮抗的分

作为一类重要的非编码小RNA，microRNA在病毒与宿主相互拮抗过程中起到了至关重要的作用。尽管目前已有一些miRNA调控乙肝病毒（HBV）复制的报道，但它们在慢乙肝患者的转归及疗效的相关性仍缺乏明确的证据。本项目前期工作发现由11个miRNA （包括let-7f，miR-939, miR-638等）组成的表达谱与慢乙肝干扰素治疗的应答密切关联。本项目原本计划研究let-7f及其家族成员调控HBV复制的机制。但经过反复实验确认，发现let-7f及其家族成员并不具有特异性调控HBV复制的生物活性。通过对表达谱中其他基因的功能探索，发现miR-939具有更显著的调控HBV复制的生物学功能。我们的研究表明，miR-939能通过靶向宿主Jmjd3, 一种组蛋白去甲基化酶，来影响HBV的复制周期。在慢乙肝患者肝组织内miR-939与Jmjd3 mRNA的水平具有显著的负相关性。Jmjd3能够加强HBV核心抗原启动子的转录活性，但令人意外的是，这一激活功能并不依赖于其内在的去甲基化酶活性，也不依赖于启动子染色质的组蛋白甲基化修饰水平的改变。后续机制研究表明，Jmjd3对核心抗原启动子的激活需要C/EBPα的协同和SWI/SNF染色质重构复合物的参与。本研究的发现扩展了对microRNA与乙肝病毒复杂、多层面的相互作用的了解，并对开发新的抗病毒疗法提供了新的启发。