Hepatitis C virus core protein shows a cytoplasmic localization and associates to cellular lipid storage droplets
Hepatitis C virus core protein shows a cytoplasmic localization and associates to cellular lipid storage droplets
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DOI：
10.1073/pnas.94.4.1200
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发表时间：
1997-02-18
影响因子：
11.1
通讯作者：
Brechot, C
中科院分区：
文献类型：
--
作者：
Barba, G;Harper, F;Brechot, C
现在有大量证据证实丙型肝炎病毒 (HCV) 核心蛋白在细胞基因表达以及病毒周期中的重要作用。因此，该蛋白质的亚细胞定位具有重要意义。然而，一些研究显示了有争议的结果：HCV 核心实际上被描述为细胞质或细胞核，具体取决于蛋白质的大小或分析的基因型。我们研究了 HCV 核心蛋白在两种不同细胞系中的定位，一种是非肝细胞系 (CHO)，另一种是肝细胞系 (HepG2)。使用核膜标记物的双重免疫荧光染色和共聚焦分析显示核心蛋白模式为细胞质和球状。这种模式不受细胞周期调节。电子显微镜分析揭示了免疫荧光中观察到的球状染色的性质。 HCV核心蛋白在脂滴表面积累，这也是非肝核心转染细胞独特的形态特征。根据密度，通过连续超速离心分离脂滴；生化分析显示甘油三酯普遍存在。此外，共聚焦显微镜显示，核心蛋白与载脂蛋白 AII 共定位于脂滴表面。此外，对长期感染 HCV 的黑猩猩的肝活检分析表明，HCV 核心位于细胞质中，位于内质网和脂滴上。这些结果清楚地定义了HCV核心蛋白的亚细胞定位，并表明HCV核心蛋白的表达与细胞脂质代谢之间的关系。
There is now abundant evidence to substantiate an important role of hepatitis C virus (HCV) core protein in cellular gene expression as well as in the viral cycle. Thus the subcellular localization of this protein has important implications. However, several studies have shown controversial results: the HCV core has been, indeed, described as cytoplasmic or nuclear depending on the size of the protein or on the genotype analyzed. We have studied the localization of the HCV core protein in two different cell lines, one nonhepatic (CHO) and the other hepatic (HepG2). Double immunofluorescence staining using a nuclear membrane marker and confocal analysis showed the core protein pattern to be cytoplasmic and globular. This pattern is not cell cycle-regulated. Electron microscopy analysis revealed the nature of the globular staining observed in immunofluorescence. The HCV core protein accumulated at the surface of lipid droplets that were also the unique morphological feature of nonhepatic core transfected cells. The lipid droplets were isolated by sequential ultracentrifugation on the basis of their density; biochemical analysis revealed a prevalence of triglycerides. In addition the core protein colocalized with apolipoprotein AII at the surface of the lipid droplets as revealed by confocal microscopy. Moreover analysis of liver biopsies from chronically HCV-infected chimpanzees revealed that HCV core is cytoplasmic and localized on the endoplasmic reticulum and on lipid droplets. These results clearly define the subcellular localization of the HCV core protein and suggest a relationship between the expression of the HCV core protein and cellular lipid metabolism.