title: Hepatitis C virus modulates lipid regulatory factor Angiopoietin-like 3 gene expression by repressing HNF-1α activity.
abstract: OBJECTIVE
  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-1α-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-1α element in ANGPTL-3 promoter was mutated, while loss of HNF-1α DNA binding to this site was recorded in the presence of HCV core. HNF-1α 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-1α-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-1α 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.
authors: Molecular Virology Laboratory, Hellenic Pasteur Institute, Athens, Greece. Electronic address: pfoka@pasteur.gr.
authors: Pelagia
authors: P
authors: Foka
authors: Molecular Virology Laboratory, Hellenic Pasteur Institute, Athens, Greece.
authors: Eirini
authors: E
authors: Karamichali
authors: Molecular Virology Laboratory, Hellenic Pasteur Institute, Athens, Greece.
authors: Georgia
authors: G
authors: Dalagiorgou
authors: Molecular Virology Laboratory, Hellenic Pasteur Institute, Athens, Greece.
authors: Elisavet
authors: E
authors: Serti
authors: 2nd Department of Internal Medicine, Medical School of Athens, Hippokration Hospital, Athens, Greece.
authors: Polyxeni P
authors: PP
authors: Doumba
authors: Molecular Virology Laboratory, Hellenic Pasteur Institute, Athens, Greece.
authors: George
authors: G
authors: Pissas
authors: Molecular Virology Laboratory, Hellenic Pasteur Institute, Athens, Greece.
authors: Athanassios
authors: A
authors: Kakkanas
authors: Molecular Virology Laboratory, Hellenic Pasteur Institute, Athens, Greece.
authors: Dorothea
authors: D
authors: Kazazi
authors: Molecular Virology Laboratory, Hellenic Pasteur Institute, Athens, Greece.
authors: Emmanouil
authors: E
authors: Kochlios
authors: Laboratory of Cellular and Molecular Neurobiology, Hellenic Pasteur Institute, Athens, Greece.
authors: Maria
authors: M
authors: Gaitanou
authors: 2nd Department of Internal Medicine, Medical School of Athens, Hippokration Hospital, Athens, Greece.
authors: John
authors: J
authors: Koskinas
authors: Molecular Virology Laboratory, Hellenic Pasteur Institute, Athens, Greece.
authors: Urania
authors: U
authors: Georgopoulou
authors: Molecular Virology Laboratory, Hellenic Pasteur Institute, Athens, Greece. Electronic address: penelopm@pasteur.gr.
authors: Penelope
authors: P
authors: Mavromara
mesh_terms: D000328:Adult; D000091303:Angiopoietin-Like Protein 3; D000075802:Angiopoietin-like Proteins; D042682:Angiopoietins / Q000235:genetics*; D004247:DNA / Q000378:metabolism; D015536:Down-Regulation; D005260:Female; D016174:Hepacivirus / Q000472:pathogenicity*; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000502:physiology*; D000071518:Liver X Receptors; D008297:Male; D008875:Middle Aged; D057093:Orphan Nuclear Receptors / Q000502:physiology; D011401:Promoter Regions, Genetic; D047488:Retinoid X Receptors / Q000502:physiology
chemical_list: C479896:ANGPTL3 protein, human; D000091303:Angiopoietin-Like Protein 3; D000075802:Angiopoietin-like Proteins; D042682:Angiopoietins; C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D000071518:Liver X Receptors; D057093:Orphan Nuclear Receptors; D047488:Retinoid X Receptors; D004247:DNA
keywords: ANGPTL-3; ApoE; ChIP; Core; ELISA; EMSA; HCV; HCV infection; HDL; HL; HNF-1α; LDL; LPL; LXR; Lipid metabolism; Mirk/Dyrk1B; NASH; ORF; PI3K; PPARβ; Phosphorylation; RLA; RXR; SREBP1; Transcriptional regulation; VLDL; angiopoietin-like 3; apolipoprotein E; chromatin immunoprecipitation; electrophoretic mobility shift assay; enzyme-linked immunosorbent assay; hepatic lipase; hepatic nuclear factor-1α; hepatitis C virus; high density lipoprotein; lipoprotein lipase; liver-X receptor; low density lipoprotein; minibrain related kinase/dual-specificity Yak related kinase 1B; non-alcoholic steatohepatitis; open reading frame; peroxisome prolifarator-activated receptor β; phosphoinositide-3-kinase; qRT-PCR; quantitative reverse-transcription polymerase chain reaction; relative luciferase activity; retinoic-X receptor; sterol regulatory element binding protein 1; very low density lipoprotein