Citation
- Authors: Foka, P., Karamichali, E., Dalagiorgou, G., Serti, E., Doumba, P. P., Pissas, G., Kakkanas, A., Kazazi, D., Kochlios, E., Gaitanou, M., Koskinas, J., Georgopoulou, U., Mavromara, P.
- Year: 2014
- Journal: J Hepatol 60 30-8
- Applications: in vitro / DNA / jetPEI
- Cell type: Hep G2
Description: Human hepatocarcinoma cells
Abstract
BACKGROUND & AIMS: HCV relies on host lipid metabolism to complete its life cycle and HCV core is crucial to this interaction. Liver secreted ANGPTL-3 is an LXR- and HNF-1alpha-regulated protein, which plays a key role in lipid metabolism by increasing plasma lipids via inhibition of lipase enzymes. Here we aimed to investigate the modulation of ANGPTL-3 by HCV core and identify the molecular mechanisms involved. METHODS: qRT-PCR and ELISA were used to assess ANGPTL-3 mRNA and protein levels in HCV patients, the JFH-1 infectious system and liver cell lines. Transfections, chromatin immunoprecipitation and immunofluorescence delineated parts of the molecular mechanisms implicated in the core-mediated regulation of ANGPTL-3 gene expression. RESULTS: ANGPTL-3 gene expression was decreased in HCV-infected patients and the JFH-1 infectious system. mRNA and promoter activity levels were down-regulated by core. The response was lost when an HNF-1alpha element in ANGPTL-3 promoter was mutated, while loss of HNF-1alpha DNA binding to this site was recorded in the presence of HCV core. HNF-1alpha mRNA and protein levels were not altered by core. However, trafficking between nucleus and cytoplasm was observed and then blocked by an inhibitor of the HNF-1alpha-specific kinase Mirk/Dyrk1B. Transactivation of LXR/RXR signalling could not restore core-mediated down-regulation of ANGPTL-3 promoter activity. CONCLUSIONS: ANGPTL-3 is negatively regulated by HCV in vivo and in vitro. HCV core represses ANGPTL-3 expression through loss of HNF-1alpha binding activity and blockage of LXR/RXR transactivation. The putative ensuing increase in serum lipid clearance and uptake by the liver may sustain HCV virus replication and persistence.