Jackel-Cram C, Babiuk LA, Liu Q. Up-regulation of fatty acid synthase promoter by hepatitis C virus core protein: genotype-3a core has a stronger effect than genotype-1b core.
J Hepatol 2007;
46:999-1008. [PMID:
17188392 DOI:
10.1016/j.jhep.2006.10.019]
[Citation(s) in RCA: 119] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/03/2006] [Revised: 10/24/2006] [Accepted: 10/25/2006] [Indexed: 12/20/2022]
Abstract
BACKGROUND/AIMS
Hepatitis C virus genotype-3a (HCV-3a) is directly linked to steatosis development. We studied the effects of HCV-3a core protein on the promoter activity of fatty acid synthase (FAS), a major enzyme involved in de novo lipid synthesis.
METHODS AND RESULTS
HCV-3a and -1b core genes were cloned and expressed. Using a FAS promoter-luciferase reporter, we demonstrated that both HCV-3a and -1b core proteins up-regulated the FAS promoter. However, HCV-3a core protein expression induced significantly higher FAS promoter activity than HCV-1b core. We further showed that FAS up-regulation by HCV core was dependent on transcription factor sterol response element binding protein-1. Mutational analysis showed that processing of HCV core protein of different genotypes was differentially involved in FAS promoter up-regulation. Although lipid droplet localization of HCV core protein was not important for FAS up-regulation, a specific amino acid residue (Phe(164)) within the FATG lipid droplet localization sequence of HCV-3a core protein played a major role in the stronger FAS activation by HCV-3a core.
CONCLUSIONS
The stronger effect of HCV-3a core protein on FAS activation in comparison to HCV-1b core could contribute to the higher prevalence and severity of steatosis in HCV-3a infections.
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