title: Modulation of fatty acid synthase enzyme activity and expression during hepatitis C virus replication.
abstract: The hepatitis C virus (HCV) induces alterations of host cells to facilitate its life cycle. Fatty acid synthase (FASN) is a multidomain enzyme that plays a key role in the biosynthesis of fatty acids and is upregulated during HCV infection. Herein, we applied activity-based protein profiling (ABPP) that allows for the identification of differentially active enzymes in complex proteomic samples, to study the changes in activity of FASN during HCV replication. For this purpose, we used an activity-based probe based on the FASN inhibitor Orlistat, and observed an increase in the activity of FASN in the presence of a subgenomic and a genomic HCV replicon as well as in chimeric SCID/Alb-uPA mice infected with HCV genotype 1a. To study the molecular basis for this increase in FASN activity, we overexpressed individual HCV proteins in Huh7 cells and observed increased expression and activity of FASN in the presence of core and NS4B, as measured by western blots and ABPP, respectively. Triglyceride levels were also elevated in accordance with FASN expression and activity. Lastly, immunofluorescence and ABPP imaging analyses demonstrated that while the abundance and activity of FASN increases significantly in the presence of HCV, its localization does not change. Together these data suggest that the HCV-induced production of fatty acids and neutral lipids is provided by an increase in FASN abundance and activity that is sufficient to allow HCV propagation without transporting FASN to the replication complexes.
authors.affiliation: Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, ON K1N 6N5, Canada.
authors.forename: Neda
authors.initials: N
authors.lastname: Nasheri
authors.forename: Michael
authors.initials: M
authors.lastname: Joyce
authors.forename: Yanouchka
authors.initials: Y
authors.lastname: Rouleau
authors.forename: Pengyu
authors.initials: P
authors.lastname: Yang
authors.forename: Shao
authors.initials: S
authors.lastname: Yao
authors.forename: D Lorne
authors.initials: DL
authors.lastname: Tyrrell
authors.forename: John Paul
authors.initials: JP
authors.lastname: Pezacki
mesh_terms: D000818:Animals; D002460:Cell Line; D064429:Fatty Acid Synthases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D005838:Genotype; D016174:Hepacivirus / Q000235:genetics / Q000502:physiology*; D006801:Humans; D007783:Lactones / Q000737:chemistry / Q000378:metabolism; D051379:Mice; D016513:Mice, SCID; D015335:Molecular Probes / Q000737:chemistry / Q000378:metabolism; D000077403:Orlistat; D014280:Triglycerides / Q000378:metabolism; D014758:Viral Core Proteins / Q000235:genetics / Q000378:metabolism; D017361:Viral Nonstructural Proteins / Q000235:genetics / Q000378:metabolism; D014779:Virus Replication
chemical_list: D007783:Lactones; D015335:Molecular Probes; C080107:NS4B protein, flavivirus; D014280:Triglycerides; D014758:Viral Core Proteins; D017361:Viral Nonstructural Proteins; C069130:nucleocapsid protein, Hepatitis C virus; D000077403:Orlistat; D064429:Fatty Acid Synthases