title: Smad7 prevents activation of hepatic stellate cells and liver fibrosis in rats.
abstract: OBJECTIVE
  Numerous studies implicate transforming growth factor (TGF)-beta signaling in liver fibrogenesis. To perturb the TGF-beta pathway during this process, we overexpressed Smad7, an intracellular antagonist of TGF-beta signaling, in vivo and in primary-cultured hepatic stellate cells (HSCs).
  
  
  METHODS
  Ligation of the common bile duct (BDL) was used to induce liver fibrosis in rats. Animals received injections of an adenovirus carrying Smad7 cDNA into the portal vein during surgery and via the tail vein at later stages. The effect of Smad7 on TGF-beta signaling and activation of HSC was further analyzed in primary-cultured cells.
  
  
  RESULTS
  Smad7-overexpressing BDL rats displayed reduced collagen and alpha-SMA expression and reduced hydroxyproline content in the liver, when compared with animals administered AdLacZ. Such a beneficial effect was also observed when Smad7 was expressed in animals with established fibrosis. Accordingly, Smad7 arrested transdifferentiation of primary-cultured HSCs. AdSmad7 infected cells remained in a quiescent stage and retained storage of vitamin A droplets. Smad7 expression totally blocked TGF-beta signal transduction, shown by inhibiting Smad2/3 phosphorylation, nuclear translocation of activated Smad complexes, and activation of (CAGA)(9)-MLP-Luc, resulting in decreased collagen I expression. Smad7 also abrogated TGF-beta-dependent proliferation inhibition of HSC. Smad7 did not decrease expression of alpha-SMA, but immunofluorescent staining with anti alpha-SMA antibodies displayed destruction of the fibrillar organization of the actin cytoskeleton.
  
  
  CONCLUSIONS
  In summary, gene transfer of Smad7 inhibits experimental fibrogenesis in vivo. Studies with isolated HSC suggest that the underlying mechanisms involve inhibition of TGF-beta signaling and HSC transdifferentiation.
authors.affiliation: Institüt für Klinische Chemie und Pathobiochemie, RWTH-Universitätsklinikum, Aachen, Germany. sdooley@ukaachen.de
authors.forename: Steven
authors.initials: S
authors.lastname: Dooley
authors.forename: Jafar
authors.initials: J
authors.lastname: Hamzavi
authors.forename: Katja
authors.initials: K
authors.lastname: Breitkopf
authors.forename: Eliza
authors.initials: E
authors.lastname: Wiercinska
authors.forename: Harun M
authors.initials: HM
authors.lastname: Said
authors.forename: Johann
authors.initials: J
authors.lastname: Lorenzen
authors.forename: Peter
authors.initials: P
authors.lastname: Ten Dijke
authors.forename: Axel M
authors.initials: AM
authors.lastname: Gressner
mesh_terms: D000199:Actins / Q000235:genetics; D000818:Animals; D019898:Autocrine Communication; D002455:Cell Division; D002478:Cells, Cultured; D024042:Collagen Type I / Q000096:biosynthesis; D004268:DNA-Binding Proteins / Q000235:genetics*; D015870:Gene Expression; D015316:Genetic Therapy; D008099:Liver / Q000166:cytology*; D008103:Liver Cirrhosis / Q000473:pathology / Q000517:prevention & control*; D051379:Mice; D019899:Paracrine Communication; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction; D051906:Smad7 Protein; D015534:Trans-Activators / Q000235:genetics*; D016212:Transforming Growth Factor beta / Q000378:metabolism; D019076:Transgenes
chemical_list: D000199:Actins; D024042:Collagen Type I; D004268:DNA-Binding Proteins; D051906:Smad7 Protein; C497807:Smad7 protein, mouse; C497808:Smad7 protein, rat; D015534:Trans-Activators; D016212:Transforming Growth Factor beta