title: Increased phosphorylation and activation of mitogen-activated protein kinase p38 in scleroderma fibroblasts.
abstract: Transforming growth factor-beta (TGF-beta) stimulates the transcription of the alpha2(I) collagen gene. The dermal fibroblast activation in systemic sclerosis (SSc) may be a result of stimulation by autocrine TGF-beta. In this study, we investigated whether p38 mitogen-activated protein kinase (MAPK) is involved in TGF-beta-induced transcriptional activation of the human alpha2(I) collagen gene in normal dermal fibroblasts and in upregulated extracellular matrix (ECM) expression in SSc fibroblasts. Type I collagen expression induced by TGF-beta was suppressed by the specific p38 MAPK inhibitors SB203580 or SB202190 in normal fibroblasts. TGF-beta induced phosphorylation and activation of p38 MAPK in normal dermal fibroblasts. Transient transfection of dominant-negative mutant p38 MAPK into normal fibroblasts abolished TGF-beta-induced promoter activity of the human alpha2(I) collagen gene in normal fibroblasts. Moreover, constitutive phosphorylation and activation of p38 MAPK was demonstrated in SSc fibroblasts, and the inhibition of p38 MAPK using specific p38 MAPK inhibitors or dominant-negative mutant p38 MAPK abolished the upregulated expression of type I collagen or fibronectin in SSc fibroblasts. These results strongly suggest the contribution of p38 MAPK signaling to the TGF-beta-mediated regulation of the human alpha2(I) collagen gene in normal dermal fibroblasts and constitutive upregulated expression of type I collagen and fibronectin in SSc fibroblasts.
authors.affiliation: Department of Dermatology, Faculty of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan. IN-DER@h.u-tokyo-ac.jp
authors.forename: Hironobu
authors.initials: H
authors.lastname: Ihn
authors.forename: Kenichi
authors.initials: K
authors.lastname: Yamane
authors.forename: Kunihiko
authors.initials: K
authors.lastname: Tamaki
mesh_terms: D000328:Adult; D002478:Cells, Cultured; D003094:Collagen / Q000235:genetics / Q000378:metabolism; D024042:Collagen Type I / Q000235:genetics / Q000378:metabolism; D020405:Dermis / Q000166:cytology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D005353:Fibronectins / Q000378:metabolism; D006801:Humans; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000502:physiology*; D008297:Male; D010766:Phosphorylation; D012595:Scleroderma, Systemic / Q000378:metabolism*; D014158:Transcription, Genetic / Q000187:drug effects / Q000502:physiology; D016212:Transforming Growth Factor beta / Q000494:pharmacology; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism*
chemical_list: D024042:Collagen Type I; D004791:Enzyme Inhibitors; D005353:Fibronectins; D016212:Transforming Growth Factor beta; D003094:Collagen; D048051:p38 Mitogen-Activated Protein Kinases