title: TGF-β-elicited induction of tissue inhibitor of metalloproteinases (TIMP)-3 expression in fibroblasts involves complex interplay between Smad3, p38α, and ERK1/2.
abstract: Transforming growth factor-β (TGF-β) promotes extracellular matrix deposition by down-regulating the expression of matrix degrading proteinases and upregulating their inhibitors. Tissue inhibitor of metalloproteinases (TIMP)-3 is an ECM-associated specific inhibitor of matrix degrading metalloproteinases. Here, we have characterized the signaling pathways mediating TGF-β-induced expression of TIMP-3. Basal and TGF-β-induced TIMP-3 mRNA expression was abolished in Smad4-deficient mouse embryonic fibroblasts and restoring Smad4 expression rescued the response. Inhibition of Smad signaling by expression of Smad7 and dominant negative Smad3 completely abolished TGF-β-elicited expression of TIMP-3 in human fibroblasts, whereas overexpression of Smad3 enhanced it. Inhibition of extracellular signal-regulated kinase 1/2 (ERK1/2) activation with PD98059 and p38 mitogen-activated protein kinase activity by SB203580 resulted in suppression of TGF-β-induced TIMP-3 expression, indicating that ERK1/2 and p38 MAPK mediate the effect of TGF-β on TIMP-3 expression. Specific activation of p38α and ERK1/2 by constitutively active mutants of MKK3b or MEK1, respectively, and simultaneous co-expression of Smad3 resulted in induction of TIMP-3 expression in the absence of TGF-β indicating that Smad3 co-operates with p38 and ERK1/2 in the induction of TIMP-3 expression. These results demonstrate the complex interplay between Smad3, p38α, and ERK1/2 signaling in the regulation of TIMP-3 gene expression in fibroblasts, which may play a role in inflammation, tissue repair, and fibrosis.
authors.affiliation: Department of Dermatology, University of Turku, and Turku University Hospital, Turku, Finland.
authors.forename: Suvi-Katri
authors.initials: SK
authors.lastname: Leivonen
authors.forename: Konstantinos
authors.initials: K
authors.lastname: Lazaridis
authors.forename: Julie
authors.initials: J
authors.lastname: Decock
authors.forename: Andrew
authors.initials: A
authors.lastname: Chantry
authors.forename: Dylan R
authors.initials: DR
authors.lastname: Edwards
authors.forename: Veli-Matti
authors.initials: VM
authors.lastname: Kähäri
mesh_terms: D015152:Blotting, Northern; D015153:Blotting, Western; D002478:Cells, Cultured; D005347:Fibroblasts / Q000378:metabolism*; D006801:Humans; D020935:MAP Kinase Signaling System; D020133:Reverse Transcriptase Polymerase Chain Reaction; D051900:Smad3 Protein / Q000502:physiology*; D019717:Tissue Inhibitor of Metalloproteinase-3 / Q000378:metabolism*; D016212:Transforming Growth Factor beta / Q000502:physiology*; D048051:p38 Mitogen-Activated Protein Kinases / Q000502:physiology*
chemical_list: C497790:SMAD3 protein, human; D051900:Smad3 Protein; D019717:Tissue Inhibitor of Metalloproteinase-3; D016212:Transforming Growth Factor beta; D048051:p38 Mitogen-Activated Protein Kinases