title: Hepatocyte growth factor (HGF) inhibits collagen I and IV synthesis in hepatic stellate cells by miRNA-29 induction.
abstract: BACKGROUND
  In chronic liver disease, hepatic stellate cells (HSC) transdifferentiate into myofibroblasts, promoting extracellular matrix (ECM) synthesis and deposition. Stimulation of HSC by transforming growth factor-β (TGF-β) is a crucial event in liver fibrogenesis due to its impact on myofibroblastic transition and ECM induction. In contrast, hepatocyte growth factor (HGF), exerts antifibrotic activities. Recently, miR-29 has been reported to be involved in ECM synthesis. We therefore studied the influence of HGF and TGF-β on the miR-29 collagen axis in HSC.
  
  
  METHODS
  HSC, isolated from rats, were characterized for HGF and Met receptor expression by Real-Time PCR and Western blotting during culture induced myofibroblastic transition. Then, the levels of TGF-β, HGF, collagen-I and -IV mRNA, in addition to miR-29a and miR-29b were determined after HGF and TGF-β stimulation of HSC or after experimental fibrosis induced by bile-duct obstruction in rats. The interaction of miR-29 with 3'-untranslated mRNA regions (UTR) was analyzed by reporter assays. The repressive effect of miR-29 on collagen synthesis was studied in HSC treated with miR-29-mimicks by Real-Time PCR and immunoblotting.
  
  
  RESULTS
  The 3'-UTR of the collagen-1 and -4 subtypes were identified to bind miR-29. Hence, miR-29a/b overexpression in HSC resulted in a marked reduction of collagen-I and -IV synthesis. Conversely, a decrease in miR-29 levels is observed during collagen accumulation upon experimental fibrosis, in vivo, and after TGF-β stimulation of HSC, in vitro. Finally, we show that during myofibroblastic transition and TGF-β exposure the HGF-receptor, Met, is upregulated in HSC. Thus, whereas TGF-β stimulation leads to a reduction in miR-29 expression and de-repression of collagen synthesis, stimulation with HGF was definitely associated with highly elevated miR-29 levels and markedly repressed collagen-I and -IV synthesis.
  
  
  CONCLUSIONS
  Upregulation of miRNA-29 by HGF and downregulation by TGF-β take part in the anti- or profibrogenic response of HSC, respectively.
authors.affiliation: Institute for Pathology, University Hospital Cologne, Cologne, Germany.
authors.forename: Monika
authors.initials: M
authors.lastname: Kwiecinski
authors.forename: Andrea
authors.initials: A
authors.lastname: Noetel
authors.forename: Natalia
authors.initials: N
authors.lastname: Elfimova
authors.forename: Jonel
authors.initials: J
authors.lastname: Trebicka
authors.forename: Stephanie
authors.initials: S
authors.lastname: Schievenbusch
authors.forename: Ingo
authors.initials: I
authors.lastname: Strack
authors.forename: Levente
authors.initials: L
authors.lastname: Molnar
authors.forename: Melanie
authors.initials: M
authors.lastname: von Brandenstein
authors.forename: Ulrich
authors.initials: U
authors.lastname: Töx
authors.forename: Roswitha
authors.initials: R
authors.lastname: Nischt
authors.forename: Oliver
authors.initials: O
authors.lastname: Coutelle
authors.forename: Hans Peter
authors.initials: HP
authors.lastname: Dienes
authors.forename: Margarete
authors.initials: M
authors.lastname: Odenthal
mesh_terms: D020413:3' Untranslated Regions; D000818:Animals; D001652:Bile Ducts / Q000473:pathology; D002454:Cell Differentiation; D024042:Collagen Type I / Q000378:metabolism*; D024141:Collagen Type IV / Q000378:metabolism*; D019295:Computational Biology / Q000379:methods; D005109:Extracellular Matrix / Q000378:metabolism; D005347:Fibroblasts / Q000378:metabolism; D005355:Fibrosis / Q000473:pathology; D055166:Hepatic Stellate Cells / Q000166:cytology*; D017228:Hepatocyte Growth Factor / Q000378:metabolism*; D008297:Male; D035683:MicroRNAs / Q000378:metabolism*; D019859:Proto-Oncogene Proteins c-met / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D016212:Transforming Growth Factor beta / Q000378:metabolism
chemical_list: D020413:3' Untranslated Regions; D024042:Collagen Type I; D024141:Collagen Type IV; C526366:MIRN29 microRNA, rat; D035683:MicroRNAs; D012333:RNA, Messenger; D016212:Transforming Growth Factor beta; D017228:Hepatocyte Growth Factor; D019859:Proto-Oncogene Proteins c-met