title: Transforming growth factor-beta repression of matrix metalloproteinase-1 in dermal fibroblasts involves Smad3.
abstract: Enhanced production of matrix metalloproteinase-1 (MMP-1, collagenase-1) is implicated in pathological tissue destruction. Transforming growth factor-beta (TGF-beta) prevents cytokine-induced MMP-1 gene expression in fibroblasts. In these studies, we examined the hypothesis that repression of MMP-1 may be mediated through the Smad signaling pathway. The results showed that Smad3 and Smad4, but not Smad1 or Smad2, mimicked the inhibitory effect of TGF-beta and abrogated interleukin-1beta (IL-1beta)-induced stimulation of MMP-1 promoter activity and NFkappaB-specific gene transcription in dermal fibroblasts. Experiments with truncation mutants indicated that both MH1 and MH2 domains of Smad3 were necessary for inhibitory activity. Dominant negative mutants of Smad3 or Smad4 and antagonistic Smad7, which disrupts ligand-induced Smad3 phosphorylation, abrogated the repression of MMP-1 transcription by TGF-beta. Similar results were obtained using immunoblot and Northern analysis. Furthermore, TGF-beta failed to repress MMP-1 promoter activity in Smad3-deficient murine embryonic fibroblasts. These results implicated cellular Smads in mediating the inhibitory effects of TGF-beta. Overexpression of the transcriptional co-activator p300, but not its histone acetyltransferase (HAT)-deficient mutant, was able to relieve repression of MMP-1 gene expression, suggesting that Smad-dependent inhibition may be due to increased competition between Smad proteins and IL-1beta signaling pathways for limiting amounts of cellular p300. Together, these results demonstrate that MMP-1 is a target for negative regulation by TGF-beta through cellular Smad3 and Smad4. Smad-mediated repression of MMP-1 gene expression may be important for preventing excessive matrix degradation induced by inflammatory cytokines; disruption of Smad signaling, as occurs in certain cancer cells, may thus be causally linked to uncontrolled tissue destruction mediated through MMP-1.
authors.affiliation: Section of Rheumatology, College of Medicine, University of Illinois, Chicago, Illinois 60607-7171, USA.
authors.forename: W
authors.initials: W
authors.lastname: Yuan
authors.forename: J
authors.initials: J
authors.lastname: Varga
mesh_terms: D000818:Animals; D001665:Binding Sites; D001667:Binding, Competitive; D015152:Blotting, Northern; D015153:Blotting, Western; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D050881:E1A-Associated p300 Protein; D005347:Fibroblasts / Q000378:metabolism*; D015971:Gene Expression Regulation, Enzymologic; D005799:Genes, Dominant; D017930:Genes, Reporter; D005822:Genetic Vectors; D006801:Humans; D015151:Immunoblotting; D020781:Matrix Metalloproteinase 1 / Q000235:genetics / Q000378:metabolism*; D061965:Matrix Metalloproteinase Inhibitors; D051379:Mice; D009154:Mutation; D016328:NF-kappa B / Q000378:metabolism; D009687:Nuclear Proteins / Q000378:metabolism; D010957:Plasmids / Q000378:metabolism; D011401:Promoter Regions, Genetic; D015398:Signal Transduction; D012867:Skin / Q000378:metabolism*; D051785:Smad Proteins; D051898:Smad1 Protein; D051899:Smad2 Protein; D051900:Smad3 Protein; D051901:Smad4 Protein; D015534:Trans-Activators / Q000378:metabolism*; D014158:Transcription, Genetic; D014162:Transfection; D016212:Transforming Growth Factor beta / Q000378:metabolism*
chemical_list: D004268:DNA-Binding Proteins; D061965:Matrix Metalloproteinase Inhibitors; D016328:NF-kappa B; D009687:Nuclear Proteins; C497399:SMAD1 protein, human; C497782:SMAD2 protein, human; C497790:SMAD3 protein, human; C497796:SMAD4 protein, human; D051785:Smad Proteins; D051898:Smad1 Protein; C497401:Smad1 protein, mouse; D051899:Smad2 Protein; C497783:Smad2 protein, mouse; D051900:Smad3 Protein; C497791:Smad3 protein, mouse; D051901:Smad4 Protein; C490810:Smad4 protein, mouse; D015534:Trans-Activators; D016212:Transforming Growth Factor beta; D050881:E1A-Associated p300 Protein; C494361:Ep300 protein, mouse; D020781:Matrix Metalloproteinase 1