E-cadherin调控肝细胞极化影响NTCP分布对HBV入胞的作用

Hepatitis B Virus (HBV) still seriously endangers public health. It is very important to understand the mechanism of HBV invading host cells for developing new therapy target. Cell polarity is reported to associate with pathogens invading, and hepatocyte polarity may decide the efficacy of HBV infection. As the pivotal adhesive molecule for epithelial cells adhesion, E-cadherin may play a key role in producing and maintaining of hepatocyte polarity. NTCP is the key receptor mediating HBV invasion, which mainly located on the basolateral membrane of polar hepatocyte. Our early work discovered that Silencing of E-cadherin by RNAi inhibited the invasion of HBV in HepG2-NTCP cells. E-cadherin interacted with NTCP by immuno precipitation and downregulation of E-cadherin reduced its membrane distribution. Downregulation of E-cadherin also changed the subcellular distribution of ZO-1 and MRP2, which demonstrated the change of cell polarity. Therefore, we proposed a hypothesis: HBV particle may conjuncts with E-cadherin and attach the cell membrane to access the receptor, NTCP. Additionally, E-cadherin directly interacts with NTCP, mediating its polar distribution on the hepatocyte basolatral membrane. Furthermore, E-cadherin may affect the efficacy of HBV invasion by influncing the polarity of hepatocytes. In that, this project aims to elaborate the mechanism by which E-cadherin affects the hepatocyte polarity and NTCP distribution and facilitate the invasion of HBV eventually. This research may enrich our knowledge about interaction between virus and host and help to explore new therapy targets.

细胞极化与病原体入侵密切相关，肝细胞极化状态可影响HBV入胞效率。E-cadherin介导的细胞间连接对形成和维持肝细胞极化状态至关重要。NTCP是HBV的重要受体，主要分布于极化肝细胞的基底膜侧。我们前期工作发现：下调E-cadherin可显著抑制HBV入胞；E-cadherin可与NTCP结合影响其胞膜分布；下调E-cadherin使极化分子ZO-1和MRP2亚细胞分布发生改变。据此，本项目提出假说：E-cadherin可与HBV结合，使之粘附于细胞膜而接近NTCP；E-cadherin也可与NTCP相互作用，协助NTCP分布至肝细胞膜而利于HBV的入胞；E-cadherin还可通过多种机制影响肝细胞的极化状态，从而影响HBV的入胞效率。为此，本项目拟综合利用细胞实验、动物实验和临床标本，探讨E-cadherin在HBV入胞中的作用。本项目的实施，将为寻找HBV新的治疗靶点提供思路。

乙型肝炎病毒感染是影响全球健康的重要公共卫生问题。病毒入侵肝细胞是感染发生的第一步，虽然近年来NTCP作为HBV 受体的发现极大地推动了HBV 入胞的研究，但病毒入胞的各种限制因素仍未完全明了。细胞极化与病原体入侵密切相关，肝细胞极化状态可影响HBV入胞效率，而E-cadherin介导的细胞间连接对形成和维持肝细胞极化状态至关重要。NTCP是HBV的重要受体，主要分布于极化肝细胞的基底膜侧。本项目旨在研究E-cadherin在HBV入胞中的作用，及其与NTCP的交互作用，希望揭示E-cadherin作为HBV入胞协同分子作用的具体机制。按照项目计划，本完成了以下研究内容：（1）E-cadherin促进HBV感染肝细胞。（2）E-cadherin促进HBV preS1与肝细胞受体NTCP结合和进入肝细胞。（3）E-cadherin对肝细胞中NTCP的表达和稳定性无明显影响，主要影响其亚细胞分布，即促进其从胞浆到胞膜。（4）E-cadherin通过与糖基化NTCP结合而从胞浆募集该受体到胞膜，进而有利于HBV preS1与胞膜上糖基化的NTCP结合和进入肝细胞。（5）E-cahderin对维持肝细胞极化状态有重要作用。本项目的实施获得了预期的实验结果，发表SCI论文4篇，中文CSCD核心库论文1篇，培养博士研究生1名，硕士研究生4名。