Cottarel Jessica, Plissonnier Marie-Laure, Kullolli Majlinda, Pitteri Sharon, Clément Sophie, Millarte Valentina, Si-Ahmed Si-Nafa, Farhan Hesso, Zoulim Fabien, Parent Romain
Pathogenesis of Hepatitis B and C - DEVweCAN LabEx, INSERM U1052-CNRS 5286, Centre de Recherche en Cancérologie de Lyon, Université de Lyon, 69008 Lyon, France.
Canary Center for Cancer Early Detection, Department of Radiology, Stanford University School of Medicine, Palo Alto, CA 94304, USA.
J Gen Virol. 2016 Jan;97(1):69-81. doi: 10.1099/jgv.0.000331. Epub 2015 Oct 29.
There is growing evidence that virus particles also contain host cell proteins, which provide viruses with certain properties required for entry and release. A proteomic analysis performed on double-gradient-purified hepatitis C virus (HCV) from two highly viraemic patients identified the phosphatidylinositol 3,5-bisphosphate 5-phosphatase FIG4 (KIAA0274) as part of the viral particles. We validated the association using immunoelectron microscopy, immunoprecipitation and neutralization assays in vitro as well as patient-derived virus particles. RNA interference-mediated reduction of FIG4 expression decreased cholesteryl ester (CE) levels along with intra- and extracellular viral infectivity without affecting HCV RNA levels. Likewise, overexpressing FIG4 increased intracellular CE levels as well as intra- and extracellular viral infectivity without affecting viral RNA levels. Triglyceride levels and lipid droplet (LD) parameters remained unaffected. The 3,5-bisphosphate 5-phosphatase active site of FIG4 was found to strongly condition these results. Whilst FIG4 was found to localize to areas corresponding to viral assembly sites, at the immediate vicinity of LDs in calnexin-positive and HCV core-positive regions, no implication of FIG4 in the secretory pathway of the hepatocytes could be found using either FIG4-null mice, in vitro morphometry or functional assays of the ERGIC/Golgi compartments. This indicates that FIG4-dependent modulation of HCV infectivity is unrelated to alterations in the functionality of the secretory pathway. As a result of the documented implication of CE in the composition and infectivity of HCV particles, these results suggest that FIG4 binds to HCV and modulates particle formation in a CE-related manner.
越来越多的证据表明，病毒颗粒还含有宿主细胞蛋白，这些蛋白赋予病毒进入和释放所需的某些特性。对两名高病毒血症患者的双梯度纯化丙型肝炎病毒（HCV）进行的蛋白质组学分析确定，磷脂酰肌醇3,5-二磷酸5-磷酸酶FIG4（KIAA0274）是病毒颗粒的一部分。我们通过免疫电子显微镜、免疫沉淀和体外中和试验以及患者来源的病毒颗粒验证了这种关联。RNA干扰介导的FIG4表达降低降低了胆固醇酯（CE）水平以及细胞内和细胞外病毒感染性，而不影响HCV RNA水平。同样，过表达FIG4增加了细胞内CE水平以及细胞内和细胞外病毒感染性，而不影响病毒RNA水平。甘油三酯水平和脂滴（LD）参数未受影响。发现FIG4的3,5-二磷酸5-磷酸酶活性位点强烈影响这些结果。虽然发现FIG4定位于与病毒组装位点相对应的区域，在钙连蛋白阳性和HCV核心阳性区域中LD的紧邻处，但使用FIG4基因敲除小鼠、体外形态测量或ERGIC/高尔基体区室的功能试验均未发现FIG4在肝细胞分泌途径中的作用。这表明FIG4对HCV感染性的调节与分泌途径功能的改变无关。由于已证明CE与HCV颗粒的组成和感染性有关，这些结果表明FIG4与HCV结合并以与CE相关的方式调节颗粒形成。
