乙肝病毒感染介导SAMHD1 O-GlcNAcylation修饰调控病毒复制的机制研究

HBV感染是严重威胁人类健康的公共卫生问题，病毒感染后引起的代谢重编程及生物学意义不明。课题组前期发现HBV感染细胞HBP代谢通路增强，UDP-GlcNAc和O-GlcNAc修饰增加，Co-IP筛选到OGT结合蛋白SAMHD1，质谱首次鉴定SAMHD1的93位丝氨酸是O-GlcNAc修饰位点。由此我们提出“HBV感染通过HBP途径介导SAMHD1的O-GlcNAc修饰调控HBV复制”的科学假说。本研究拟在HBV复制细胞、转基因小鼠和慢性HBV感染者临床标本中，阐明HBV通过代谢重编程促进宿主限制因子SAMHD1 O-GlcNAc修饰，在抗病毒天然免疫中的作用机理，同时还将在HBV感染的细胞和动物模型中，观察调控O-GlcNAc糖基化的小分子药物的抗病毒疗效。本研究将解析HBP代谢通路调控SAMHD1的O-GlcNAc修饰机制，为设计靶向调控O-GlcNAc修饰的抗病毒药物提供新的思路。

Hepatitis B virus (HBV) infection is a common cause of liver diseases, including acute and chronic hepatitis, cirrhosis and hepatocellular carcinoma, which remains a major global public health threat. Current therapies improve both quality of life and survival of hepatitis B patients, however, novel therapeutic approaches are still needed to achieve a functional cure of HBV infection. ..Our preliminary data indicated that hepatitis B virus (HBV) infection upregulates glucose transporter 1 (GLUT1) expression, promotes hexosamine biosynthesis pathway (HBP) and enhances downstream protein O-linked β-N-acetylglucosamine (O-GlcNAc) modification. HBP-mediated O-GlcNAcylation positively regulates host antiviral responses against HBV in vitro and in vivo. Mechanistically, O-GlcNAc transferase (OGT)-mediated O-GlcNAcylation of sterile alpha motif and histidine/aspartic acid domain-containing protein 1 (SAMHD1) on serine 93 is critical for its antiviral activity. ..Based on our preliminary data, we hypothesized that HBV infection could enhance the O-GlcNAcylation modification of target protein-SAMHD1 through elevated hexosamine biosynthesis pathway, and thus eliciting its antiviral activity. In this study, HBV-replicating cells, HBV transgenic mouse model as well as HBV-infected clinical samples will be used to examine the metabolic responses of host cells to HBV infection and to evaluate the effects of protein O-GlcNAcylation on HBV replication. We will further investigate the molecular mechanism that how post-translational modification, such as O-GlcNAcylation modification induced by metabolism reprogramming, regulates the antiviral function of host restriction factor SAMHD1 during HBV infection. In HBV-replicating cells and HBV transgenic mouse model, we will explore the antiviral effects of OGA inhibitor TMG via inhibition of SAMHD1 O-GlcNAcylation. Our study will provide a novel link between HBP pathway, O-GlcNAc modification and antiviral innate immunity by targeting SAMHD1, and provides new drug target for treating a range of viruses including HBV, HCV and human immunodeficiency virus-1 (HIV-1).