title: Tumor necrosis factor-alpha and interferon-gamma suppress the activation of human type I collagen gene expression by transforming growth factor-beta 1. Evidence for two distinct mechanisms of inhibition at the transcriptional and posttranscriptional levels.
abstract: Regulation of human type I procollagen gene expression was studied in cultured fibroblasts both at the transcriptional and posttranscriptional level. Transcriptional regulation was examined in cultures transfected with a human pro alpha 2(I) collagen promoter/reporter gene (chloramphenicol acetyltransferase) construct, while posttranscriptional regulation was assessed by parallel determinations of type I procollagen mRNA steady-state levels. Transforming growth factor-beta 1 (TGF-beta 1) elicited a marked, approximately 5-23-fold, enhancement of pro alpha 2(I) collagen promoter activity, which was accompanied by an elevation of type I procollagen mRNA levels. This enhancement of gene expression was suppressed by tumor necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma), as determined at mRNA steady-state level, but two distinct mechanisms were involved. TNF-alpha suppressed the pro alpha 2(I) collagen promoter activity, whereas IFN-gamma had only a minimal effect at transcriptional level. The effects of TNF-alpha and IFN-gamma were synergistic, suggesting that combination of these two factors may potentially provide pharmacologic means to counteract tissue deposition of collagen in diseases involving TGF-beta.
authors.affiliation: Department of Dermatology, Jefferson Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania 19107.
authors.forename: V M
authors.initials: VM
authors.lastname: Kähäri
authors.forename: Y Q
authors.initials: YQ
authors.lastname: Chen
authors.forename: M W
authors.initials: MW
authors.lastname: Su
authors.forename: F
authors.initials: F
authors.lastname: Ramirez
authors.forename: J
authors.initials: J
authors.lastname: Uitto
mesh_terms: D000818:Animals; D002460:Cell Line; D002478:Cells, Cultured; D003094:Collagen / Q000235:genetics*; D005786:Gene Expression Regulation; D006133:Growth Substances / Q000494:pharmacology; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology*; D051379:Mice; D011401:Promoter Regions, Genetic; D014158:Transcription, Genetic; D014162:Transfection; D016212:Transforming Growth Factor beta / Q000494:pharmacology*; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
chemical_list: D006133:Growth Substances; D016212:Transforming Growth Factor beta; D014409:Tumor Necrosis Factor-alpha; D007371:Interferon-gamma; D003094:Collagen