title: Hepatitis C virus infection mediates cholesteryl ester synthesis to facilitate infectious particle production.
abstract: Cholesterol is a critical component of the hepatitis C virus (HCV) life cycle, as demonstrated by its accumulation within infected hepatocytes and lipoviral particles. To cope with excess cholesterol, hepatic enzymes ACAT1 and ACAT2 produce cholesteryl esters (CEs), which are destined for storage in lipid droplets or for secretion as apolipoproteins. Here we demonstrate in vitro that cholesterol accumulation following HCV infection induces upregulation of the ACAT genes and increases CE synthesis. Analysis of human liver biopsy tissue showed increased ACAT2 mRNA expression in liver infected with HCV genotype 3, compared with genotype 1. Inhibiting cholesterol esterification using the potent ACAT inhibitor TMP-153 significantly reduced production of infectious virus, but did not inhibit virus RNA replication. Density gradient analysis showed that TMP-153 treatment caused a significant increase in lipoviral particle density, suggesting reduced lipidation. These data suggest that cholesterol accumulation following HCV infection stimulates the production of CE, a major component of lipoviral particles. Inhibition of CE synthesis reduces HCV particle density and infectivity, suggesting that CEs are required for optimal infection of hepatocytes.
authors.affiliation: Storr Liver Unit, Westmead Millennium Institute, University of Sydney and Westmead Hospital, Sydney, Australia.
authors.forename: Scott A
authors.initials: SA
authors.lastname: Read
authors.affiliation: Storr Liver Unit, Westmead Millennium Institute, University of Sydney and Westmead Hospital, Sydney, Australia.
authors.forename: Enoch
authors.initials: E
authors.lastname: Tay
authors.affiliation: Storr Liver Unit, Westmead Millennium Institute, University of Sydney and Westmead Hospital, Sydney, Australia.
authors.forename: Mahsa
authors.initials: M
authors.lastname: Shahidi
authors.affiliation: Storr Liver Unit, Westmead Millennium Institute, University of Sydney and Westmead Hospital, Sydney, Australia.
authors.forename: Jacob
authors.initials: J
authors.lastname: George
authors.affiliation: Centre for Infectious Diseases and Microbiology, Marie Bashir Institute for Infectious Diseases and Biosecurity, University of Sydney at Westmead Hospital, Sydney, Australia.|Storr Liver Unit, Westmead Millennium Institute, University of Sydney and Westmead Hospital, Sydney, Australia.
authors.forename: Mark W
authors.initials: MW
authors.lastname: Douglas
mesh_terms: D045744:Cell Line, Tumor; D002788:Cholesterol Esters / Q000096:biosynthesis*; D016174:Hepacivirus / Q000201:enzymology* / Q000235:genetics; D006526:Hepatitis C / Q000821:virology; D022781:Hepatocytes / Q000821:virology; D006801:Humans; D010671:Phenylurea Compounds / Q000494:pharmacology; D012333:RNA, Messenger / Q000096:biosynthesis; D012367:RNA, Viral / Q000096:biosynthesis; D002785:Sterol O-Acyltransferase / Q000037:antagonists & inhibitors / Q000096:biosynthesis* / Q000235:genetics; D015854:Up-Regulation; D014779:Virus Replication; D000097587:Sterol O-Acyltransferase 2
chemical_list: D002788:Cholesterol Esters; D010671:Phenylurea Compounds; D012333:RNA, Messenger; D012367:RNA, Viral; D002785:Sterol O-Acyltransferase; D000097587:Sterol O-Acyltransferase 2; C088280:N-(4-(2-chlorophenyl)-6,7-dimethyl-3-quinolyl)-N'-(2,4-difluorophenyl)urea; C493492:sterol O-acyltransferase 1