外泌体（exosomes）介导肝癌诊断标志物GP73调控丙型肝炎病毒粒子释放的分子机制研究

Hepatitis c virus (HCV) infection is a major cause of chronic liver disease, making it one of the greatest public health threats of this century. Exosomes have recently been recognized as important mediators of intercellular communication. Recent studies have shown that the exosomal viral RNA transfer is a new route of HCV transmission, and HCV secretion is regulated by proteins critical for the production of exosomes, but the detailed mechanism is unknown. GP73 is a newly discovered serum marker for early diagnosis of hepatocellular carcinoma, but its function is unknown. Previous studies have demonstrated the upregulation of GP73 in the liver samples and sera of HCV-infected patients. However, the function and regulatory mechanism of GP73 in HCV infection at the cellular level remain unknown. In our previous study, the existence of GP73 in exosomes and the interplay between GP73 and HCV on a cellular level are discovered for the first time. Both the intracellular and exosomal GP73 protein are upregulated by HCV infection. Meanwhile, HCV production is significantly enhanced when GP73 is overexpressed, but dramatically inhibited when the expression of GP73 is silenced. In addition, the release of HCV virion is regulated by GP73, indicating that exosomes probably play a critical role in the regulation of HCV secretion by GP73. The goal of this study is to elucidate the exosomes-mediated mechanism of HCV particles release regulated by GP73 and the mechanism underlying the upregulation of GP73 during HCV infection, which will provide new targets for the development of anti-HCV drugs, and greatly advance our present limited knowledge of the function of GP73, the role of exosomes in HCV life cycle，and the mechanism underlying HCV virons release.

丙型肝炎病毒（HCV）感染严重危害人类健康。外泌体是细胞间物质转运和信息通讯的重要媒介，近期研究表明外泌体介导了HCV传播的全新途径，HCV毒粒的释放依赖于与外泌体形成相关的蛋白，但详细机制不明。GP73是新发现的肝癌早期诊断血清标志物，在HCV感染患者的血清及肝组织中GP73表达显著上升，但功能未知。我们的前期研究首次发现GP73存在于外泌体中，并在细胞水平首次证实GP73与HCV存在相互调控：HCV的感染增强细胞内及外泌体中GP73的表达；GP73调控HCV病毒颗粒的释放。在充分的前期研究基础上，我们推断外泌体是GP73调控HCV毒粒释放的重要媒介。本项目将深入研究外泌体介导GP73调控HCV毒粒释放及HCV感染增强GP73表达的分子机制，预期将极大促进对GP73生理功能、外泌体在HCV生命周期中作用以及HCV毒粒释放详细过程等方面的了解，为抗HCV药物的设计开发提供新的靶点的理论依据

丙型肝炎病毒（HCV）感染严重危害人类健康。外泌体是细胞间物质转运和信息通讯的重要媒介，近期研究表明外泌体介导HCV传播的全新途径，HCV毒粒的释放依赖于与外泌体形成相关的蛋白，但详细机制不明。GP73是新发现的肝癌早期诊断血清标志物，在HCV感染患者的血清及肝组织中GP73表达显著增加，但功能未知。我们的前期研究在细胞水平首次证实GP73与HCV存在相互调控：HCV的感染增强细胞内及外泌体中GP73的表达；GP73调控HCV毒粒的释放。在充分的前期研究基础上，我们推断外泌体是GP73与HCV相互调控的重要媒介。本项目围绕HCV增强GP73表达的机制、外泌体介导GP73与HCV相互调控的机制、以及寻找新的HCV药物靶点展开研究，分别取得了以下原创性结果:①HCV感染可能通过上调IL-1β来增强GP73的表达；②GP73存在于外泌体样囊泡（ELV）中，而HCV感染可以增加ELV中的GP73蛋白水平。 GP73可以通过ELV传递到受体细胞并抑制受体细胞针对病毒感染的天然免疫反应，我们推测HCV复制增加ELV中的GP73使更多的GP73通过ELV传递到受体细胞进而抑制其天然免疫反应从而促进HCV的传播；③我们发现酰基辅酶A：胆固醇酰基转移酶的抑制剂Avasimibe具有高效和广谱的抗HCV活性，其主要通过下调MTTP的表达从而干扰APOB及APOE的转运进而抑制HCV病毒粒子的包装过程。本研究首次将肝癌诊断标志物GP73、细胞通讯的重要媒介外泌体、以及HCV有机的联系起来。将有助于增加目前对于GP73的生理功能、外泌体在HCV感染中具体作用、以及GP73与HCV相互调控的分子机制等方面匮乏的了解，也有利于我们理解HCV在感染复制过程中与宿主细胞之间的相互调控，为设计更有效的抗病毒药物及治疗方法提供靶点和理论依据。