title: Abrogation of transforming growth factor-beta signaling by SMAD7 inhibits collagen gel contraction of human dermal fibroblasts.
abstract: Human fibroproliferative disorders like hypertrophic scarring of the skin are characterized by increased contractility and excess extracellular matrix synthesis. A beneficial role of transforming growth factor (TGF)-beta in wound healing was proposed; however, chronic stimulation by this cytokine leads to fibrosis. In the present report, the intracellular TGF-beta signaling in fibroblasts derived from hypertrophic scars and normal skin was examined. In an attempt to intervene in profibrogenic TGF-beta functions, ectopic expression of Smad7 or dominant negative Smads3/4 completely inhibited contractility of scar-derived and normal fibroblasts after suspension in collagen gels. Both cell types displayed constitutive Smad2/3 phosphorylation and (CAGA)9-MLP-Luc activity with expression and phosphorylation of Smad3 being predominant in hypertrophic scar-derived fibroblasts. Down-regulation of intrinsic signaling with various TGF-beta antagonists, e.g. soluble TGF-beta receptor, latency-associated peptide, and anti-TGF-beta1 antibodies, confirms autocrine TGF-beta stimulation of both cell populations. Further, Smad7 expression inhibited alpha1 (I) collagen and alpha-smooth muscle actin expression. In summary, our data indicate that autocrine TGF-beta/Smad signaling is involved in contractility and matrix gene expression of fibroblasts from normal and hypertrophic scars. Smad7 inhibits these processes and may exert beneficial effects on excessive scar formation.
authors.affiliation: Plastische und Handchirurgie, Chirurgische Universitätsklinik Erlangen-Nürnberg, 91054 Erlangen, Germany.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Kopp
authors.forename: Ellen
authors.initials: E
authors.lastname: Preis
authors.forename: Harun
authors.initials: H
authors.lastname: Said
authors.forename: Bernd
authors.initials: B
authors.lastname: Hafemann
authors.forename: Lucia
authors.initials: L
authors.lastname: Wickert
authors.forename: Axel M
authors.initials: AM
authors.lastname: Gressner
authors.forename: Norbert
authors.initials: N
authors.lastname: Pallua
authors.forename: Steven
authors.initials: S
authors.lastname: Dooley
mesh_terms: D000199:Actins / Q000378:metabolism; D015152:Blotting, Northern; D015153:Blotting, Western; D003094:Collagen / Q000737:chemistry / Q000378:metabolism*; D016207:Cytokines / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism*; D015536:Down-Regulation; D004591:Electrophoresis, Polyacrylamide Gel; D005109:Extracellular Matrix / Q000378:metabolism; D005347:Fibroblasts / Q000378:metabolism*; D018014:Gene Transfer Techniques; D005799:Genes, Dominant; D005822:Genetic Vectors; D006801:Humans; D015151:Immunoblotting; D008024:Ligands; D008156:Luciferases / Q000378:metabolism; D009130:Muscle, Smooth / Q000378:metabolism; D010455:Peptides / Q000737:chemistry; D010766:Phosphorylation; D012333:RNA, Messenger / Q000378:metabolism; D015398:Signal Transduction; D012867:Skin / Q000378:metabolism; D051900:Smad3 Protein; D051901:Smad4 Protein; D051906:Smad7 Protein; D015534:Trans-Activators / Q000378:metabolism*; D016212:Transforming Growth Factor beta / Q000378:metabolism*
chemical_list: D000199:Actins; D016207:Cytokines; D004268:DNA-Binding Proteins; D008024:Ligands; D010455:Peptides; D012333:RNA, Messenger; C497790:SMAD3 protein, human; C497796:SMAD4 protein, human; C497806:SMAD7 protein, human; D051900:Smad3 Protein; D051901:Smad4 Protein; D051906:Smad7 Protein; D015534:Trans-Activators; D016212:Transforming Growth Factor beta; D003094:Collagen; D008156:Luciferases