β2糖蛋白I联合膜联蛋白II在HBV入侵肝细胞初始环节中的作用研究

Beta2-glycoprotein I(beta2-GPI) is an abundant glycoprotein in liver. We've verified the specific combination between beta2-GPI and recombinated HBsAg. The specific protein has been discovered and identified as annexin II on the cell membrane of human liver cell and SMMC-7721 cell line. HBV and the large HBsAg can directly increase beta2-GPI expression. High expression of beta2-GPI facilitated the binding of HBsAg to cell surfaces. Beta2-GPI colocalized with sodium taurocholate co-transporting polypeptide on the cell membrane, which benefits for HBV binding to NTCP. The activated NTCP can phosphorylate annexin II, which make annexin II migrate to cell membrane for binding to beta2-GPI-HBV complex. This will contribute to HBV entry into hepatocytes. This complishment of study can provide new insights into the route of human HBV entry into hepatocytes.

β2糖蛋白I( beta2-GPI)由肝细胞产生，在血浆中含量丰富。前期工作证明beta2-GPI与重组乙肝病毒表面抗原蛋白（rHBsAg）特异结合，发现人原代肝细胞及肝癌细胞SMMC-7721细胞膜上存在与beta2-GPI特异结合的膜联蛋白II（annexinII）。且证实，HBV和大表面抗原（LHBsAg）直接增强beta2-GPI表达，高表达beta2-GPI促进HBsAg与细胞表面结合；beta2-GPI与HBV受体钠离子牛磺胆酸共转运多肽（NTCP）共定位于细胞膜上，有利于HBV与受体结合。本研究探讨beta2-GPI联合annexinII调节HBsAg与细胞表面的结合能力，HBV与NTCP结合使NTCP活化，促进annexinII磷酸化而迁移到细胞膜，与beta2-GPI-HBV复合物结合，有利于HBV入侵肝细胞。本项目为HBV入侵肝细胞途径研究提供新思路。

β2糖蛋白I（beta2-glycoprotein I，beta2-GPI）是血浆中含量丰富的一种单链糖蛋白，主要由肝细胞合成，是HBV感染的急性时相反应蛋白。本课题组前期研究证实，beta2-GPI与重组乙肝病毒表面抗原蛋白（rHBsAg）具有高亲和性。进一步研究发现，HBV感染肝细胞及肝癌组织中beta2-GPI高表达，HBV和L-HBsAg 能直接增强 beta2-GPI表达，而beta2-GPI抑制HBsAg分泌，导致内质网应激相关蛋白BIP、CHOP、XBP-1表达明显升高。且在L-HBsAg与beta2-GPI共转染293T细胞中BIP、CHOP、XBP-1升高更明显。综上，HBV感染肝细胞，使beta2-GPI表达上调，进一步抑制HBsAg分泌，导致HBsAg在细胞内聚集，引起内质网应激，促进乙肝相关性肝细胞癌的发生。本研究成果为揭示肝癌发病机制提供新思路，为肝癌治疗提供新靶点。.此外，我们构建了HepG2-NTCP细胞模型以进行HBV感染相关实验，但HBV感染后HBsAg表达水平偏低，不利于后续实验进行。已与法国科学院沟通，待获得HepaRG细胞使用权后进一步完成HBV感染相关实验，补充提交相关研究成果。