title: Tumor necrosis factor-alpha-induced proteolytic activation of pro-matrix metalloproteinase-9 by human skin is controlled by down-regulating tissue inhibitor of metalloproteinase-1 and mediated by tissue-associated chymotrypsin-like proteinase.
abstract: The proteolytic activation of pro-matrix metalloproteinase (MMP)-9 by conversion of the 92-kDa precursor into an 82-kDa active form has been observed in chronic wounds, tumor metastasis, and many inflammation-associated diseases, yet the mechanistic pathway to control this process has not been identified. In this report, we show that the massive expression and activation of MMP-9 in skin tissue from patients with chronically unhealed wounds could be reconstituted in vitro with cultured normal human skin by stimulation with transforming growth factor-beta and tumor necrosis factor (TNF)-alpha. We dissected the mechanistic pathway for TNF-alpha induced activation of pro-MMP-9 in human skin. We found that proteolytic activation of pro-MMP-9 was mediated by a tissue-associated chymotrypsin-like proteinase, designated here as pro-MMP-9 activator (pM9A). This unidentified activator specifically converted pro-MMP-9 but not pro-MMP-2, another member of the gelatinase family. The tissue-bound pM9A was steadily expressed and not regulated by TNF-alpha, which indicated that the cytokine-mediated activation of pro-MMP-9 might be regulated at the inhibitor level. Indeed, the skin constantly secreted tissue inhibitor of metalloproteinase-1 at the basal state. TNF-alpha, but not transforming growth factor-beta, down-regulated this inhibitor. The TNF-alpha-mediated activation of pro-MMP-9 was tightly associated with down-regulation of tissue inhibitor of metalloproteinase-1 in a dose-dependent manner. To establish this linkage, we demonstrate that the recombinant tissue inhibitor of metalloproteinase-1 could block the activation of pro-MMP-9 by either the intact skin or skin fractions. Thus, these studies suggest a novel regulation for the proteolytic activation of MMP-9 in human tissue, which is mediated by tissue-bound activator and controlled by down-regulation of a specific inhibitor.
authors: Division of Plastic and Reconstructive Surgery, Department of Surgery, The Keck School of Medicine, University of Southern California, 1450 San Pablo Street, Los Angeles, CA 90033, USA.
authors: Yuan-Ping
authors: YP
authors: Han
authors: Yih-Dar
authors: YD
authors: Nien
authors: Warren L
authors: WL
authors: Garner
mesh_terms: D015153:Blotting, Western; D002455:Cell Division; D053818:Chymases; D016207:Cytokines / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation; D004591:Electrophoresis, Polyacrylamide Gel; D004789:Enzyme Activation; D005347:Fibroblasts / Q000378:metabolism; D006801:Humans; D015603:Keratinocytes / Q000378:metabolism; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism*; D008954:Models, Biological; D011994:Recombinant Proteins / Q000378:metabolism; D012697:Serine Endopeptidases / Q000737:chemistry* / Q000378:metabolism*; D012867:Skin / Q000378:metabolism; D019715:Tissue Inhibitor of Metalloproteinase-1 / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism / Q000494:pharmacology*
chemical_list: D016207:Cytokines; D011994:Recombinant Proteins; D019715:Tissue Inhibitor of Metalloproteinase-1; D014409:Tumor Necrosis Factor-alpha; D012697:Serine Endopeptidases; C463979:pro-MMP-9 activator; D053818:Chymases; D020780:Matrix Metalloproteinase 9