日本乙型脑炎感染调控宿主GRP78表达的分子机制

Japanese encephalitis virus (JEV) is one of the most critical zoonotic pathogen by causing irreversible damage to the host central nervous system. Unfolded protein response (UPR) is activated by host cell to against the endoplasmic reticulum stress (ER stress) which is caused by JEV infection. However, JEV also can take benefits for its multiplication by manipulating UPR. Although the regulation mechanism was still unclear, the main UPR effector protein GRP78 was secreted upon viral infection. GRP78 was an important protein for JEV E protein folded, Virus particles matured and prevention of cell apoptosis. This study intends to investigate three important UPR signaling pathways-PERK, ATF6 and IRE1, analyze the UPR signaling pathways that regulation GRP78 expression, and dig out the JEV encoding protein that regulation GRP78 expression. The results of this research can be constructing support for further studies on JEV replication mechanism. Moreover, this study is valuable to develop JEV cure medicine by pointing out some potential drug targets.

日本乙型脑炎病毒（JEV）是一种危害严重的人兽共患病原，可对宿主中枢神经系统造成不可逆损伤。宿主细胞通过激活未折叠蛋白反应（UPR）来减轻JEV感染引起内质网应激（ER stress），但病毒也能通过对UPR的精细操控来达到复制与增殖的目的。前期研究结果表明，JEV感染后宿主UPR主要效应蛋白GRP78上调表达显著，且GRP78在帮助JEV E蛋白折叠，病毒粒子成熟、释放以及延缓宿主细胞凋亡等方面有着重要作用，但JEV感染调控GRP78表达的具体机制尚不清楚。因此，本项目拟从UPR的3条重要信号通路——PERK、ATF6和IRE1出发，解析JEV感染后调控GRP78表达的UPR信号通路，并从JEV编码蛋白与主要信号通路上信号/效应分子的互作入手，较为全面的揭示JEV感染调控宿主GRP78表达的分子细节和关键分子，为阐明JEV的感染与复制机理以及抗JEV感染的治疗新药研发奠定基础。

本研究建立了JVE感染细胞的炎症模型和内质网应激模型，分析了JEV感染后内质网应激的UPR信号通路，发现在BV-2细胞模型中，JEV感染可以激活UPR的三条信号通路。乙脑M、NS3、NS4a、NS4b、NS5a和NS5b蛋白可以上调感染细胞GRP78的表达。不同的JEV蛋白对3条不同的UPR信号通路激活各有侧重，其中C、NS2b、NS3、NS4a、NS4b、NS5b可以激活PERK信号通路；C、Pr、NS1可激活ATF6通路；所有蛋白均可激活XPB1信号通路。而在JEV炎症抑制组中，UPR信号通路的激活被抑制。综上，本研究阐明了JEV感染后调控内质网应激的分子机制，从分子水平上证实JEV感染中内质网应激-炎症的相互关联，为JEV抗炎治疗药物的开发及药物靶点的筛选奠定了基础。