title: Transcriptional and post-transcriptional regulation of 72-kDa gelatinase/type IV collagenase by transforming growth factor-beta 1 in human fibroblasts. Comparisons with collagenase and tissue inhibitor of matrix metalloproteinase gene expression.
abstract: The temporal aspects and mechanisms of the regulation of the matrix metalloproteinase (MMP) 72-kDa gelatinase/type IV collagenase (MMP-2) by transforming growth factor-beta 1 (TGF-beta 1) were investigated in early passage human gingival fibroblasts and compared with the regulation of the genes for collagenase (MMP-1) and TIMP, the tissue inhibitor of MMPs. Northern hybridization analyses revealed that 1.0 ng/ml TGF-beta 1 increased the abundance of MMP-2 mRNA/cell approximately 1.5-fold at 24 h, an increase similar to that observed in the level of [35S]methionine pulse-labeled MMP-2 at 24 h (1.9-fold). At 48 and 72 h, the increase in MMP-2 mRNA abundance remained elevated by 1.5-2.2-fold on a per cell basis whereas TIMP mRNA levels were elevated by up to 3.3-fold. In contrast, the relative levels of collagenase mRNA were reduced by 66-75%. The changes in the MMP-2, collagenase, and TIMP mRNA concentrations in response to TGF-beta 1 were blocked by cycloheximide indicating that protein synthesis was required to mediate the effects of TGF-beta 1 on these mRNA levels. TGF-beta 1 was also found to increase the half-life of the MMP-2 mRNA from approximately 46 to approximately 150 h but did not alter the stability of TIMP mRNA (t1/2 approximately 60 h). Nuclear run-off transcription assays revealed that MMP-2 gene transcription was increased approximately 5-fold 7 h following TGF-beta 1-treatment but returned to control levels by 24 h. In comparison, increased TIMP gene transcription was only detectable after 24 h whereas collagenase gene transcription, although low in control cells, was undetectable at 24 h. Gene transcription, mRNA levels, and message stability of the genes for the extracellular matrix proteins type I collagen and fibronectin were also increased by TGF-beta 1. Thus, the similarity in the control of MMP-2, alpha 1 (I) procollagen, and fibronectin expression at the transcriptional and post-transcriptional levels indicates that these genes may share regulatory elements. In comparison, TGF-beta 1 reduced the level of collagenase mRNA and increased the level of TIMP mRNA as a result of altered transcriptional activities, through pathways that required protein synthesis, and without changes in mRNA stability.
authors.affiliation: Medical Research Council Group in Periodontal Physiology, Faculty of Dentistry, University of Toronto, Ontario, Canada.
authors.forename: C M
authors.initials: CM
authors.lastname: Overall
authors.forename: J L
authors.initials: JL
authors.lastname: Wrana
authors.forename: J
authors.initials: J
authors.lastname: Sodek
mesh_terms: D015152:Blotting, Northern; D002460:Cell Line; D002467:Cell Nucleus / Q000502:physiology; D003513:Cycloheximide / Q000494:pharmacology; D016326:Extracellular Matrix Proteins / Q000378:metabolism; D005786:Gene Expression Regulation; D006023:Glycoproteins / Q000235:genetics; D006801:Humans; D066298:In Vitro Techniques; D020778:Matrix Metalloproteinase 2; D008666:Metalloendopeptidases / Q000235:genetics*; D003012:Microbial Collagenase / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics; D019714:Tissue Inhibitor of Metalloproteinases; D014158:Transcription, Genetic; D016212:Transforming Growth Factor beta / Q000502:physiology*
chemical_list: D016326:Extracellular Matrix Proteins; D006023:Glycoproteins; D012333:RNA, Messenger; D019714:Tissue Inhibitor of Metalloproteinases; D016212:Transforming Growth Factor beta; D003513:Cycloheximide; D008666:Metalloendopeptidases; D020778:Matrix Metalloproteinase 2; D003012:Microbial Collagenase