Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.21.68 (tissue plasminogen activator)
 11,311 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Heparin is a potent inhibitor of arterial smooth muscle cell (SMC) migration and proliferation in vivo and in vitro. We propose that heparin affects these SMC functions by interfering with either the expression or the activity of secreted proteases required for cell movement. We have reported that heparin selectively inhibits the expression of tissue-type plasminogen activator in SMCs during mitogenesis. In this study we show that the gene expression of another kind of protease, interstitial collagenase, is induced by fetal bovine serum and is also suppressed by heparin. The inhibitory effect on the induced collagenase mRNA is specific to heparin-like molecules and does not depend on the anticoagulant activity of heparin. The induction of the collagenase gene depends on the protein kinase C pathway, since it can be induced by phorbol esters such as phorbol 12-myristate 13-acetate and blocked by inhibitors such as H-7 and staurosporine. In transient transfection assays with chloramphenicol acetyltransferase constructs containing the phorbol ester-responsive element introduced into baboon SMCs, heparin inhibits transcription induced by serum or phorbol 12-myristate 13-acetate. These results support the conclusion that, in primate SMCs, interstitial collagenase gene transcription mediated by the phorbol ester-responsive element is blocked by heparin.
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PMID:Heparin inhibits collagenase gene expression mediated by phorbol ester-responsive element in primate arterial smooth muscle cells. 131 15

The preovulatory surge of gonadotropins activates a cascade of proteolytic enzymes resulting in the rupture of the follicular wall and the release of a fertilizable ovum during ovulation. In the rat the process is initiated by a rise in follicular tissue-type plasminogen activator, produced predominantly in granulosa cells. Recent studies revealed a preovulatory increase in ovarian collagenolytic activity in vivo and an increase in activatable collagenase in vitro. In view of the complicated control of mammalian collagenase synthesis and activity by local inhibitors and activators, we examined the expression of ovarian interstitial and type IV collagenases and tissue inhibitor of metalloproteinase (TIMP) mRNA after an ovulatory stimulus. Ovarian mRNA was isolated from immature PMSG-treated rats 3, 6, and 9 h after hCG stimulation. Northern blot analyses revealed a mRNA of 1.7 kilobases (kb) hybridizing with the human interstitial collagenase cDNA probe. The levels of this mRNA showed a 25-fold increase between 3-6 h after hCG stimulation. The human cDNA probe of collagenase IV hybridized with a mRNA of 3.1 kb, which showed only a 4-fold increase 9 h after hCG treatment. The interstitial collagenase mRNA was expressed in both granulosa cells of preovulatory follicles and the residual ovarian tissue, whereas the expression of collagenase IV mRNA was limited to the residual tissue. Inhibitors of eicosanoid synthesis, previously shown to block ovulation and the LH/hCG-induced rise in ovarian collagenolysis, suppressed the gonadotropic stimulation of interstitial collagenase mRNA, but slightly stimulated that of collagenase IV. The mouse cDNA probe of TIMP hybridized with a 0.9-kb mRNA, which was stimulated by hCG to reach a maximum (7- to 8-fold increase) between 6-9 h after stimulation. TIMP was expressed and stimulated in both the granulosa cells and the residual tissue. Inhibitors of eicosanoid synthesis did not affect the gonadotropic stimulation of TIMP mRNA. These data support the suggested role of interstitial collagenase in follicle rupture and the essential role of eicosanoids in the mediation of gonadotropic stimulation of interstitial collagenase production and action. The observed stimulation of TIMP mRNA expression by the gonadotropin and the lack of any effect of eicosanoid synthesis inhibitors on this action of LH/hCG offer an additional mechanism by which these inhibitors may block ovulation. Thus, the suppression of ovulation by inhibitors of eicosanoid synthesis may result from selective inhibition of interstitial collagenase expression and undisturbed gonadotropin-stimulated TIMP expression.
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PMID:Preovulatory changes in ovarian expression of collagenases and tissue metalloproteinase inhibitor messenger ribonucleic acid: role of eicosanoids. 165 86

To identify agents and mechanisms responsible for the thickened basement membranes characteristic of diabetic angiopathy we examined the effects of high glucose (30 mM) on the expression of genes related to extracellular matrix composition and turnover and investigated whether the changes induced by high glucose were mimicked and sustained by activation of protein kinase C or A. In human umbilical vein endothelial cells high glucose increased fibronectin, collagen IV, tissue plasminogen activator (tPA), and plasminogen activator-inhibitor 1 (PAI-1) mRNA levels 2-fold but did not affect type IV and interstitial collagenase expression. Acute treatment with phorbol esters resulted in increased collagen IV, tPA, PAI-1, and interstitial collagenase mRNAs; the type IV collagenase mRNA levels were instead suppressed to 50% of control. Upon longer exposure to phorbol esters (48 h) suppression of fibronectin and PAI-1 mRNAs also occurred. Intracellular elevation of cAMP led to over-expression of fibronectin and type IV collagenase and potentiated the effects of phorbol esters on collagen IV, tPA, and interstitial collagenase expression. The mRNA changes induced by high glucose occurred in the absence of protein kinase C activation or cAMP elevation. These studies indicate that events other than activation of protein kinase C or A bridge high ambient glucose to changes in endothelial cell gene expression that may contribute to diabetic angiopathy.
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PMID:Expression of genes related to the extracellular matrix in human endothelial cells. Differential modulation by elevated glucose concentrations, phorbol esters, and cAMP. 171 80

Heparin is a potent inhibitor of the proliferation and migration of vascular smooth muscle cells. This agent selectively inhibits the transcription of tissue-type plasminogen activator and interstitial collagenase, probably by decreasing the binding of activator protein-1 (AP-1) to phorbol ester-responsive elements in the promoters of these genes. Decreased AP-1 binding is not due to a direct inhibition by heparin, since heparinase digestion of nuclear extracts prepared from heparin-treated smooth muscle cells does not restore AP-1 binding activity. Treatment of cells with heparin suppresses the expression of Jun B, one of the components of AP-1. The major effect of heparin is at the level of posttranslational modification of Jun B. Results from pulse-chase labeling experiments show that the newly synthesized Jun B is rapidly converted to a higher-molecular-weight form and that conversion is suppressed by heparin. Evidence is presented suggesting that the heparin-inhibited event is phosphorylation of Jun B.
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PMID:Heparin decreases activator protein-1 binding to DNA in part by posttranslational modification of Jun B. 801 74

Heparin inhibits the migration and proliferation of arterial smooth muscle cells and modifies the extracellular matrix. These effects may be the result of heparin's effects on proteinases that degrade the matrix. We have previously reported that heparin inhibits the induction of tissue-type plasminogen activator and interstitial collagenase mRNA. We have investigated the possibility that heparin affects other members of the matrix metalloproteinase family. Phorbol ester increased the levels of mRNA of collagenase, 92-kD gelatinase and stromelysin as well as the synthesis of these proteins. These effects were inhibited by heparin, but not by other glycosaminoglycans, in a dose-dependent manner. The induction of these matrix metalloproteinases was also inhibited by staurosporine and pretreatment with phorbol ester indicating the involvement of the protein kinase C pathway. In contrast, the 72-kD gelatinase was expressed constitutively and was not affected by phorbol ester or heparin. Tissue inhibitor of metalloproteinase-1 was expressed constitutively and was slightly increased by phorbol ester. It was not affected by heparin. Thus, heparin inhibits the production of four proteinases (tissue plasminogen activator, collagenase, stromelysin and 92-kD gelatinase) that form an interdependent system capable of degrading all the major components of the extracellular matrix.
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PMID:Heparin inhibits the induction of three matrix metalloproteinases (stromelysin, 92-kD gelatinase, and collagenase) in primate arterial smooth muscle cells. 818 30

Constitutive overexpression of both urokinase and matrix metalloproteinase (MMP) activity is frequently observed in individual malignant tumors. In this study we describe the combined contribution of these distinct enzyme systems to the invasive phenotype of a highly metastatic human melanoma cell line (M24met). M24met cells were found to secrete a spectrum of MMPs, including interstitial collagenase, type IV collagenases (M(r) 92,000 and 72,000 progelatinases), and stromelysin. Urokinase, but not tissue-type plasminogen activator, was detected in M24met-conditioned media and on cell surfaces. The contribution of these enzymes to extracellular matrix dissolution was determined by exploiting specific inhibitors, namely tissue inhibitor of the metalloproteinases-2 and plasminogen activator inhibitor-2. Due to the coexpression of urokinase and MMP-dependent activity, M24met cells were observed to degrade multiple components of the extracellular matrix and to significantly degrade both interstitial and basement membrane matrices. Urokinase-dependent removal of matrix glycoprotein was observed to precede MMP-dependent collagenolysis as a prerequisite rate-limiting step. We present evidence which suggests that this temporal relationship is imposed by the structural architecture of the matrix such that matrix glycoprotein serves to protect associated collagen from MMP-dependent degradation. In addition to mediating significant collagenolysis, MMP activity was further implicated in the dissolution of matrix tropoelastin. Urokinase/plasmin activity was not found to be required for MMP-zymogen activation.
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PMID:Melanoma-mediated dissolution of extracellular matrix: contribution of urokinase-dependent and metalloproteinase-dependent proteolytic pathways. 842 5

We established an immortalized cell line from endothelial cells derived from a human coronary artery, isolated at autopsy from 76-year-old male, by transfecting the cells with origin-minus simian virus 40 DNA. These cells showed SV40 T antigen in the nuclei and Ulex europaeus I agglutinin and factor VIII-related antigen, as endothelial cell markers, in their cytoplasm. This cell line synthesized prostacyclin, tissue-type plasminogen activator (tPA), and plasminogen activator inhibitor-1 (PAI-1) as well as produced the proform of matrix metalloproteinase 1, which was activated by cultivating the cells with plasminogen. These findings reveal that this immortalized endothelial cell line retains characteristics of human coronary endothelial cells, indicating that this cell line is useful for studying atherogenesis of the coronary artery.
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PMID:Establishment and characterization of immortalized human coronary endothelial cells. 852 34

The cellular events causing pathological extracellular matrix (ECM) accumulation in vivo are not well understood. Prolonged serial passage of several cell types in culture leads to increased production of extracellular matrix (ECM) proteins, but the mechanism for these putative fibrotic changes is not known. Here, human fetal glomerular mesangial cells were subjected to serial passage (P) in culture and the expression of ECM proteins, proteases and protease inhibitors was comprehensively evaluated. From P11 through P14, a series of phenotypic changes occurred. Steady-state expression of mRNA for alpha 1 chains of type III and type IV (but not type I) collagen, and for laminin beta 1 and gamma 1, increased 2- to 8-fold, while expression of mRNA for interstitial collagenase (MMP-1) and gelatinase A (MMP-2) virtually ceased. Expression of tissue-type plasminogen activator (tPA) mRNA also decreased markedly. Expression of mRNA for the tissue inhibitor of metalloproteinases (TIMP)-1, and of the smaller of two mRNA species for the PA inhibitor PAI-1, ceased by P14. There was a switch in expression of the two species of TIMP-2 mRNA: whereas the ratio of signal intensity comparing the 3.5 kb mRNA species to the 1.0 kb species was 5:1 up to P11, it was reversed (1:5) at P14 and later. Serial passage also led to changes in protein expression, with increased type IV collagen and laminin, but decreased interstitial collagenase and gelatinase A. The cells showed a progressive increase in staining for type IV collagen. These findings define the appearance of a matrix-accumulating phenotype in later-passage mesangial cells. Matrix expansion in vivo has been associated with increased transforming growth factor (TGF)-beta synthesis; the cells were found to show at least 5-fold increased expression of TGF-beta 1 mRNA from P8 to P16. However, treatment of P9 or P10 cells with graded doses of TGF-beta 1 increased expression of both collagen IV and gelatinase A mRNA and did not alter the ratio of signal intensity for TIMP-2 mRNA species. Thus, assumption of a matrix-accumulating phenotype by these cultured fetal glomerular mesangial cells is not accelerated by exogenous TGF-beta. These data describe an in vitro model of mesangial cell matrix turnover in which matrix accumulation could result from a concerted increase in ECM synthesis and decrease in ECM degradation.
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PMID:Increased expression of extracellular matrix proteins and decreased expression of matrix proteases after serial passage of glomerular mesangial cells. 892 13