title: Fatty acid synthase is up-regulated during hepatitis C virus infection and regulates hepatitis C virus entry and production.
abstract: Hepatitis C virus (HCV) is a major human pathogen that causes serious illness, including acute and chronic hepatitis, cirrhosis, and hepatocellular carcinoma. Using a mass spectrometry-based proteomics approach, we have identified 175 proteins from a cell culture supernatant fraction containing the HCV genotype 2a (JFH1) virus, among which fatty acid synthase (FASN), the multifunctional enzyme catalyzing the de novo synthesis of fatty acids, was confirmed to be highly enriched. Subsequent studies showed that FASN expression increased in the human hepatoma cell line, Huh7, or its derivative, upon HCV infection. Blocking FASN activity by C75, a pharmacological FASN inhibitor, led to decreased HCV production. Reduction of FASN by RNA interference suppressed viral replication in both replicon and infection systems. Remarkably, FASN appeared to be selectively required for the expression of claudin-1, a tight junction protein that was recently identified as an entry coreceptor for HCV, but not for the expression of another HCV coreceptor, CD81. The decrease in Claudin-1 expression resulting from FASN inhibition was accompanied by a decrease in transepithelial electric resistance of Huh7 cells, implying a reduction in the relative tightness of the cell monolayer. Consequently, the entry of human immunodeficiency virus-HCV pseudotypes was significantly inhibited in C75-treated Huh7 cells.
  
  
  CONCLUSIONS
  As far as we know, this is the first line of evidence that demonstrates that HCV infection directly induces FASN expression, and thus suggests a possible mechanism by which HCV infection alters the cellular lipid profile and causes diseases such as steatosis.
authors.affiliation: Department of Infectious Diseases and Microbiology, University of Pittsburgh Cancer Institute, University of Pittsburgh, Pittsburgh, PA 15261, USA.
authors.forename: Wei
authors.initials: W
authors.lastname: Yang
authors.forename: Brian L
authors.initials: BL
authors.lastname: Hood
authors.forename: Sara L
authors.initials: SL
authors.lastname: Chadwick
authors.forename: Shufeng
authors.initials: S
authors.lastname: Liu
authors.forename: Simon C
authors.initials: SC
authors.lastname: Watkins
authors.forename: Guangxiang
authors.initials: G
authors.lastname: Luo
authors.forename: Thomas P
authors.initials: TP
authors.lastname: Conrads
authors.forename: Tianyi
authors.initials: T
authors.lastname: Wang
mesh_terms: D002460:Cell Line; D045744:Cell Line, Tumor; D064429:Fatty Acid Synthases / Q000235:genetics* / Q000378:metabolism; D016174:Hepacivirus / Q000235:genetics / Q000502:physiology*; D006526:Hepatitis C / Q000201:enzymology*; D006801:Humans; D007668:Kidney; D008113:Liver Neoplasms; D012367:RNA, Viral / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015854:Up-Regulation / Q000502:physiology*; D014771:Virion / Q000502:physiology; D014779:Virus Replication / Q000502:physiology*
chemical_list: D012367:RNA, Viral; D064429:Fatty Acid Synthases