retromer复合体在丙肝病毒复制过程中的功能研究

Host cell autophagy has a close connection with HCV life cycle. It is reported that HCV infection can induce autophagy so that it can hijack host factors involved in autophagy for its own sake. More regulators of virus-induced autophagy are yet to be discovered, furthermore, whether this kind of autophagy is complete or not is still under debating. The retromer complex functions in retrograde transport of transmembrane cargo from endosomes to the trans-Golgi network (TGN). Our preliminary data suggested that retromer is involved in autophagy. By using live cell imaging, we captured the dynamic relationship between retromer and LC3- the biomarker of autophagosome. Based on our previous data, we propose that retromer functions in HCV replication through regulating autophagy pathway. To test this hypothesis, further studies are needed, including 1) Examine the precise step which retromer promotes HCV replication, 2) Explore the biological function of retromer in virus-induced autophagy. This project will discover the mechanism by which retromer regulates HCV replication, which has scientific significance.

宿主细胞自噬对于病毒的生命周期有着非常重要的影响，丙肝病毒在宿主细胞内的复制需要挟持利用自噬。其中，有哪些宿主因子参与调节自噬，仍有待进一步发现；并且该自噬过程周期是否完整，即从自噬小体到自噬溶酶体，尚有争议。Retromer复合体主要负责介导跨膜蛋白从胞内体到反式高尔基体的囊泡运输。申请人在前期工作中发现retromer复合体参与细胞自噬，并在活细胞状态下，和自噬小体的分子标记LC3动态相关。基于前期研究基础，本项目拟以retromer复合体为切入点，探索以其为代表的胞内囊泡运输通路参与调节丙肝病毒复制的生物学机制，着重阐明（1）retromer复合体参与病毒复制的精确步骤，（2）retromer复合体在病毒诱导自噬过程中的分子机制。本研究的展开将揭示 retromer在丙肝病毒复制过程中的作用机制，具有重要的科学意义。

丙型肝炎由丙型肝炎病毒(HCV)引起，全球约1.7 亿人感染了丙肝病毒。磷酯酰肌醇-4-磷酸（phosphatidylinositol-4-phosphate, PI4P）是一类细胞膜结构上带负电的磷脂，大量富集于丙型肝炎病毒（HCV）复制区域。作为磷酯酰肌醇-4-磷酸的效应蛋白，逆转运复合体（retromer）是否在丙肝病毒复制区域卸货仍有待深入研究。本课题重点探究retromer在丙肝病毒复制中的作用。研究发现retromer的关键组分Vps35与丙肝病毒非结构蛋白5A（NS5A）存在相互作用。在丙肝病毒JFH1侵染的细胞中，Vps35与NS5A以及PI4P存在共定位。敲降retromer后削弱了HCV病毒的复制水平。进一步研究表明，PI4P促使retromer复合体的货物蛋白阳离子非依赖6-磷酸甘露糖受体（Cation-independent mannose-6-phosphate receptor, CIMPR）卸货到病毒复制区域，参与丙肝病毒复制。该研究丰富了PI4P相关宿主因子在HCV复制中作用机制，为基于病毒宿主相互作用的潜在靶标研究提供了新思路。