title: Hepatitis C virus core protein stimulates fibrogenesis in hepatic stellate cells involving the obese receptor.
abstract: Hepatitis C virus core protein (HCVcp), which is secreted by infected cells, is reported as an immunomodulator in immune cells. However, the effects of HCVcp on hepatic stellate cells (HSCs), the key cells in liver fibrosis, still remain unclear. In this study, we investigated the effects of HCVcp on obese receptor (ObR) related downstream signaling pathways and fibrogenic gene expression in HSCs. LX-2, a human HSC line, was incubated with HCVcp. Inhibitors and short interfering RNAs were used to interrogate the mechanisms of HCVcp action on HSCs. HCVcp (20-100 ng/ml) concentration-dependently stimulated α-smooth muscle actin (α-SMA) protein expression and mRNA expression of α-SMA, procollagen α2(I) and TGF-β1 genes, with a plateau of 220% of controls at 100 ng/ml. HCVcp induced mRNA and protein expression of ObR. Blocking of Ob-Rb with a neutralizing antibody inhibited phosphorylation of signal transducer and activator of transcription 3 (STAT3) and AMPKα stimulated by HCVcp. Furthermore, knockdown of Ob-Rb down-regulated HCVcp-induced STAT3, AKT, and AMPKα phosphorylation, and reversed HCVcp-suppressed mRNA expression of matrix metalloproteinase (MMP)-1, peroxisome proliferator-activated receptor (PPAR)γ and sterol regulatory element binding protein-1c (SREBP-1c) genes. AMPKα signaling blockade reversed HCVcp-suppressed SREBP-1c mRNA expression. HCVcp stimulated reactive oxygen species formation and gp91(phox) (a component of NADPH oxidase) protein expression, together with AKT phosphorylation, leading to suppression of PPARγ and SREBP-1c genes. Our results provide a new finding that HCVcp induced ObR-dependent Janus Kinase (JAK) 2-STAT3, AMPKα, and AKT signaling pathways and modulated downstream fibrogenetic gene expression in HSCs.
authors.affiliation: Institute of Traditional Medicine, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Ching-Fen
authors.initials: CF
authors.lastname: Wu
authors.forename: Yun-Lian
authors.initials: YL
authors.lastname: Lin
authors.forename: Yi-Tsau
authors.initials: YT
authors.lastname: Huang
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D000199:Actins / Q000096:biosynthesis / Q000235:genetics; D057134:Antibodies, Neutralizing / Q000276:immunology; D002460:Cell Line; D024042:Collagen Type I / Q000235:genetics; D016174:Hepacivirus / Q000235:genetics / Q000378:metabolism; D055166:Hepatic Stellate Cells / Q000378:metabolism* / Q000821:virology; D018936:Hepatitis C Antigens / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D053614:Janus Kinase 2 / Q000378:metabolism; D008103:Liver Cirrhosis; D020781:Matrix Metalloproteinase 1 / Q000235:genetics; D047495:PPAR gamma / Q000235:genetics / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D034622:RNA Interference; D012333:RNA, Messenger / Q000096:biosynthesis; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species / Q000378:metabolism; D054411:Receptors, Leptin / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D050796:STAT3 Transcription Factor / Q000037:antagonists & inhibitors / Q000378:metabolism; D051780:Sterol Regulatory Element Binding Protein 1 / Q000235:genetics; D053773:Transforming Growth Factor beta1 / Q000235:genetics; D014758:Viral Core Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: C541116:ACTA2 protein, human; D000199:Actins; D057134:Antibodies, Neutralizing; D024042:Collagen Type I; D018936:Hepatitis C Antigens; C515448:LEPR protein, human; D047495:PPAR gamma; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species; D054411:Receptors, Leptin; D050796:STAT3 Transcription Factor; C494086:STAT3 protein, human; D051780:Sterol Regulatory Element Binding Protein 1; D053773:Transforming Growth Factor beta1; D014758:Viral Core Proteins; C069130:nucleocapsid protein, Hepatitis C virus; D053614:Janus Kinase 2; D051057:Proto-Oncogene Proteins c-akt; D055372:AMP-Activated Protein Kinases; C522360:MMP1 protein, human; D020781:Matrix Metalloproteinase 1