The effect of cofilin on HCV core protein association with lipid droplet and on lipid droplet redistribution

Unrestricted The hepatitis C virus (HCV) is a leading causative agent associated with chronic liver disease. The core protein of HCV associates with lipid droplets (LDs) by its C-terminal domain, D2.; Cofilin, an actin depolymerizing factor, is activated in HCV JFH1 infected cells, and activated cofilin rearranges the f-actin filaments. In this project, using confocal laserscanning microscopy, I demonstrated that cofilin does not affect HCV core protein interaction with LDs. The movement of HCV core protein to the surface of LD was not actin-dependent translocation.; In addition, LD accumulation was observed in the perinulear region, where HCV core colocalized with LDs in HCV JFH1 transfected Huh7.5 cells. To study cofilin’s effect on LD redistribution, I examined LD localization in JFH1 RNA transfected cells with the expression plasmid of different cofilin mutants. Results revealed that LD aggregation at the periphery of the nucleus did not rely on f-actin when core recruits the HCV replication complex and other viral proteins to produce infectious HCV particles.

丙型肝炎病毒（HCV）是引发慢性肝脏疾病的主要病原体之一。HCV的核心蛋白可通过其C端结构域D2与脂滴（LDs）相结合；丝切蛋白（Cofilin）作为一种肌动蛋白解聚因子，在感染HCV JFH1株的细胞中被激活，活化的丝切蛋白可重排丝状肌动蛋白（f-actin）纤维。本项目借助共聚焦激光扫描显微镜开展实验，结果证实丝切蛋白并不会影响HCV核心蛋白与脂滴的结合过程。HCV核心蛋白向脂滴表面的转运过程并不依赖肌动蛋白介导的移位作用。
此外，在转染了HCV JFH1的Huh7.5细胞中，可观察到脂滴在核周区域聚集，且HCV核心蛋白与脂滴在此处存在共定位现象。为探究丝切蛋白对脂滴重分布的影响，本研究针对携带不同丝切蛋白突变体的表达质粒，检测了转染了JFH1 RNA的细胞中脂滴的定位情况。研究结果显示，当核心蛋白招募HCV复制复合物及其他病毒蛋白以生成具有感染性的HCV颗粒时，细胞核外周的脂滴聚集并不依赖丝状肌动蛋白。