Hepatitis C virus induced changes in cellular lipids - identifying novel host antiviral drug target

Abstract

Nearly 300,000 Australians and 200 million people throughout the world have been exposed to the hepatitis C virus (HCV). Furthermore, over 10,000 new infections are reported on an annual basis. HCV is associated with chronic disease leading to hepatic fibrosis that may progress to liver failure and cancer, and is a leading cause of chronic hepatitis, cirrhosis and hepatocellular carcinoma. Hepatitis C virus (HCV) replication is closely linked to lipid metabolism. Therefore, lipidomic analysis of HCV infected hepatic cells can offer insights into the pathogenesis of HCV infection and identify molecular targets that can serve as potential targets for new treatments. Results: HP-TLC showed increased amounts of phosphatidylcoline in lipid extracts from whole cells and from ER fractions of JFH1 infected Huh-7 cells. PC was the only phospholipid species detected in purified lipid droplets, and was significantly increased in infected cells. PYTC1 (CTP:phosphocholine cytidylyltransferase) and PEMT (phosphatidylethanolamine N-methyltransferase) are the rate limiting enzymes of PC biosynthesis in hepatocytes. Silencing PYTC1 had no effect on HCV replication or infectivity. However, when PEMT was silenced, both viral replication and infectivity were decreased by more than 50%, and less lipids accumulation was observed. Conclusion: Our data reveal global changes in lipid abundance, particularly in the ER, which are predicted to impact the HCV life cycle and pathogenesis. We report increased PC content in the ER and in lipid droplets. Our data suggest that in HCV infected cells the minor PC synthesis pathway is most important, as inhibiting PEMT inhibits replication and production of infectious virus.