Apolipoprotein J is an essential host factor for hepatitis C virus particle assembly

Abstract

Hepatitis C virus (HCV) infection not only induces hepatic diseases but also leads to disorder of lipid and glucose metabolism HCV depends on lipid droplets (LDs) for viral particle assembly and very-low density lipoproteins (VLDLs) for virion egression However the components and locations for this process remain unidentified Apolipoprotein J (apoJ) serves as a Golgi-resident molecular chaperone which can be upregulated by glucose and is secreted to extracellular space along with the route of VLDLs This study investigated the effects of apoJ on HCV life cycle HCV infection could elevate intracellular apoJ expression in primary human hepatocytes Silencing of apoJ expression by siRNA strategy reduced intracellular and extracellular HCV infectivity and extracellular HCV RNA in HCV-infected Huh7 5 hepatoma cells whereas intracellular HCV RNA was accumulated in HCV-infected cells ApoJ was shown to interact with HCV core and NS5A proteins by immunoprecipitation and could further stabilize the protein complex of HCV core and NS5A HCV infection facilitated the dispersion of intracelluar apoJ along with Golgi to encircle LDs and the dispersed apoJ colocalized with the core NS5A HCV RNA LDs endoplasmic reticulum (ER) Golgi and ER-Golgi membrane contact site Furthermore the interplay among glucose apoJ and HCV particle production was investigated Serum apoJ was positively correlated with fasting blood glucose concentration and HCV RNA titer in chronic hepatitis C patients Increase of glucose concentration in culture medium of HCV-infected Huh7 5 cells could upregulate apoJ expression In conclusion the glucose-stimulated apoJ protein facilitates infectious HCV particle assembly via stabilization of core-NS5A interaction which encircles LDs and locates at the ER-Golgi membrane contact site

Date of Award	2014 Jul 16
Original language	English
Supervisor	Kung-Chia Young (Supervisor)