B组柯萨奇病毒干扰心肌细胞线粒体稳态的机制研究

Coxsackievirus B (CVB) is the major pathogen of human viral myocarditis and dilated cardiomyopathy. Presently, effective therapy is not available. The 3C protease of CVB, plays an essential role in virus pathogenesis, which can cleave host proteins specifically. The maintenance of mitochondrial homeostasis is essential for the myocardial function, mitophagy could eliminate the damaged or effete mitochondria, which is a vital pathway regulating mitochondrial homeostasis. Our previous study demonstrated that the 3C protease of CVB may cleave host proteins specifically, and mitophagy can be inhibited by CVB infection. Based on the above, we speculate CVB can impair cardiomyocytes through disrupting mitophagy. This study was designed to investigate the mechanism of coxsackivirus B disrupting myocardial mitophagy through in vivo and in vitro approaches: (1) To make sure that CVB infection can inhibit mitophagy in cardiac cells. (2) To elucidate the mechanism of CVB interdicting mitophagy. (3) To evaluate the changes of myocardial structure and function, and the subsequent aggravation of host damage caused by CVB through inhibiting mitophagy. This study would uncover a novel significant mechanism for the cardiac damage associated with CVB infection, which could provide a new target for drug discovery treating CVB infection.

B组柯萨奇病毒（CVB）是病毒性心肌炎及扩张型心肌病的主要病原，尚无有效治疗手段。其3C蛋白酶可特异性切割宿主蛋白，在病毒致病中发挥重要作用。维持线粒体稳态是心肌细胞发挥正常功能的关键，线粒体自噬可清除损伤或衰老的线粒体，是调控线粒体稳态的关键环节之一。我们前期研究显示CVB 3C蛋白酶有可能切割线粒体自噬关键分子Parkin，从而抑制线粒体自噬水平。据此推测CVB通过干扰线粒体自噬，破坏线粒体稳态，进而导致心肌细胞损伤。本项目将通过体内和体外实验阐明CVB干扰心肌细胞线粒体稳态的机制：①明确CVB感染抑制心肌细胞线粒体自噬；②阐明CVB抑制线粒体自噬的分子机制；③评价CVB通过抑制线粒体自噬对心肌结构功能及能量代谢的影响。本项目可能揭示CVB对宿主细胞造成损伤的新的分子机制，并为研发抗CVB药物提供新靶点。

B组柯萨奇病毒（Coxsackievirus B，CVB）是病毒性心肌炎及扩张型心肌病的主要病原。由于缺乏特异性抗病毒药物，病毒性心肌炎的治疗主要依靠支持性治疗。CVB 3C蛋白酶可特异性切割宿主蛋白，在病毒致病中发挥重要作用。线粒体是一种双层膜结构的细胞器，参与ATP产生、磷脂合成和信号转导等，在凋亡、固有免疫和细胞分化过程中起到极其重要的作用。维持线粒体稳态是心肌细胞发挥正常功能的关键，线粒体自噬（mitophagy）可清除损伤或衰老的线粒体，是调控线粒体稳态的关键环节之一。哺乳动物细胞中线粒体自噬的机制可分为两类：Parkin依赖型和Parkin非依赖型线粒体自噬。我们前期研究显示CVB 3C蛋白酶有可能影响线粒体自噬关键分子Parkin，从而调控线粒体自噬水平。本项目通过体内和体外实验阐明CVB干扰心肌细胞线粒体稳态的机制：（1）CVB感染导致线粒体损伤；（2）CVB通过自噬途径降解线粒体；（3）CVB诱导的线粒体自噬是Parkin依赖的；（4）明确了CVB 3C蛋白酶可能是调控线粒体自噬的主要功能蛋白；（5）CVB通过促进ROS产生诱导线粒体自噬；（6）CVB诱导的线粒体自噬与TOM复合物及PINK1磷酸化无关。本项目对进一步完善CVB致病机制有重要意义，并为研发抗CVB药物提供新靶点。