Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.24.3 (collagenase)
 18,340 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A series of experiments using isolated rat hepatocytes was carried out to establish rat liver cells in suspension as a physiological model for examining GH responses, and to determine whether acute recombinant bovine GH (rbGH) treatment of rat liver cells increased glucose output and/or suppressed fatty acid synthesis from lactate. Rat liver cells were isolated by collagenase perfusion and incubated in short-term (less than 60 min) suspension. The amount of insulin, glucagon or vasopressin required to elicit a half-maximal response was within the physiological range of the circulating hormone. When hepatocytes from normal rats were acutely (less than 60 min) treated with 0, 0.1, 10, 100 or 1000 nmol rbGH/l, rates of hepatocyte glucose output and fatty acid synthesis were unaltered. In addition, acute rbGH treatment (1000 nmol/l) did not alter hepatocyte responsiveness to insulin or vasopressin. However, acute rbGH treatment of hepatocytes isolated from hypophysectomized rats significantly (P less than 0.05) increased the rate of glucose output twofold and moderately (P less than 0.10) enhanced fatty acid synthesis. The accelerated rate of glucose production was not accompanied by an increase in the amount of glycogen phosphorylase-a. The observations with liver cells from hypophysectomized rats are not consistent with a GH receptor-transducing mechanism which is like that for glucagon (adenylate cyclase-linked) or insulin (tyrosine kinase-linked).
 ...
PMID:Growth hormone acutely increases glucose output by hepatocytes isolated from hypophysectomized rats. 267 Dec 41

Recent studies have shown that Basic Fibroblast Growth Factor increases bone resorption and increases interstitial collagenase mRNA and protein in osteoblasts. We examined the effect of bFGF on a 1.8-kb fragment of the rabbit collagenase promoter linked to a chloramphenicol acetyl transferase CAT construct stably transfected into mouse osteoblastic MC3T3-E1 cells. Treatment with bFGF (10(-8)M) for 24 h caused a 3-fold increase in collagenase-CAT activity. CAT activity in a construct without the collagenase promoter was not regulated by 48 h treatment with bFGF (10(-8)M). Neither indomethacin nor staurosporine blocked the effect of bFGF on collagenase-CAT activity in these cells. However, the stimulatory effect of bFGF on collagenase-CAT activity was inhibited by genistein and herbimycin A, which are tyrosine kinase inhibitors. These data show for the first time that bFGF transcriptionally regulates collagenase gene expression in osteoblasts through a protein tyrosine kinase-dependent pathway.
 ...
PMID:Transcriptional regulation of the collagenase gene by basic fibroblast growth factor in osteoblastic MC3T3-E1 cells. 767 39

We have previously shown that during wound healing migrating keratinocytes, which are in contact with the dermal matrix, express interstitial collagenase, whereas basal epidermal cells, which reside on an intact basement membrane, do not. Duplicating this in vivo pattern, collagenase production was induced in primary human keratinocytes grown on native type I collagen, but only background levels of enzyme were detected in cells cultured on denatured type I collagen or on Matrigel. Using genistein, herbimycin A, and sodium orthovanadate, we show that tyrosine kinase activity was required for collagen-mediated induction of keratinocyte collagenase. Similarly, collagenase steady-state mRNA levels and the activity of a transfected human collagenase-promoter CAT construct were inhibited by genistein and enhanced by orthovanadate. Staurosporine and H-7 also blocked collagenase production, indicating that protein kinase C activity was also required for collagen-mediated induction of keratinocyte collagenase. All inhibitory effects were dose-dependent, and no compound significantly affected total protein synthesis. Furthermore, both tyrosine kinase and protein kinase C inhibitors blocked phorbol ester-mediated induction of collagenase, but only protein kinase C antagonists abrogated phorbol ester-mediated induction of c-fos mRNA. These data suggest that similar signal transduction pathways are used by various agonists to mediate the stimulation of interstitial collagenase production.
 ...
PMID:Collagen-stimulated induction of keratinocyte collagenase is mediated via tyrosine kinase and protein kinase C activities. 796 3

By applying Western blot analysis using anti-phosphotyrosine antibodies, primary human dermal fibroblasts were examined after having been cultured on type I collagen-coated surfaces or in free-floating type I collagen gels. In both systems cells showed enhanced tyrosine phosphorylation of a M(r) 120,000 protein (pp120) and of a M(r) 42,000 protein (pp42). Phosphorylation was apparent 6 h at the latest after initiation of the culture and was only slightly induced on polylysine or on plastic. In contrast to pp42, pp120 was rapidly dephosphorylated in cells suspended by trypsinization or released from collagen gels by collagenase treatment, but regained phosphorylation in cells cultured in/on type I collagen. Two human sarcoma cell lines (HT-1080 and RD) exhibited identical tyrosine phosphorylation of pp120 but not of pp42. pp120 is identical with pp125FAK, a novel tyrosine kinase localized in focal adhesions, as proved by immunological cross-reactivity with anti-pp125FAK antibodies. Our results suggest that tyrosine phosphorylation is involved in signal transduction triggered by two- and three-dimensional type I collagen-fibroblast contact.
 ...
PMID:Three-dimensional contact with type I collagen mediates tyrosine phosphorylation in primary human fibroblasts. 812 56

Treatment of cells with agents that damage DNA leads to the induction of numerous genes. Recent studies aimed at understanding the events preceding the transcriptional activation of some of these DNA damage-inducible genes in mammalian cells have demonstrated that various extranuclear protein kinases are involved in the signaling cascades. The mammalian GADD153 gene, a member of the CCAAT enhancer-binding protein family of transcription factors, is highly induced by a variety of DNA-damaging agents as well as by certain growth arrest conditions and oxidative stresses. We have examined the effects of numerous protein kinase and phosphatase inhibitors on the DNA damage-induced expression of GADD153, to identify the signal transduction components involved in its transcriptional regulation. In contrast to the transcriptional activation of c-jun and collagenase in response to DNA damage, GADD153 induction involves neither protein kinase C nor tyrosine kinases but does appear to require an unidentified serine-threonine-kinase. Elevation of intracellular glutathione levels by treatment with N-acetylcysteine did not affect the methyl methanesulfonate-induced expression of the GADD153 gene, although it did diminish cadmium chloride-induced expression. These findings suggest that oxidative stress and DNA damage regulate GADD153 transcription through different pathways. Based on our findings and those of others with respect to other DNA damage-inducible genes, we propose a model depicting the complex pathways which appear to be involved in the regulation of mammalian genes in response to genotoxic stress and in which the DNA damage-induced expression of GADD153 represents a unique pathway independent of either protein kinase C or tyrosine kinase.
 ...
PMID:The pathway regulating GADD153 induction in response to DNA damage is independent of protein kinase C and tyrosine kinases. 813 9

Degradation and tissue remodeling of the extracellular matrix in the normal glomerulus occur through the coordinate action of neutral metalloproteinases, which are in turn regulated by specific inhibitors. Many of these proteins can be secreted by mesangial cells. In the current study, gene regulation of a rat matrix metalloproteinase, interstitial collagenase and its tissue inhibitor of metalloproteinase-1 (TIMP-1), was investigated by Northern blot analysis. Stimulation of rat mesangial cell (RMC) collagenase by interleukin 1 beta (IL-1 beta) produced an increase (> 45-fold) in mRNA which peaked at 12 h. Lesser effects on the TIMP-1 mRNA expression were observed in response to IL-1 beta. Indomethacin did not influence the effect of IL-1 beta on collagenase, and exogenous prostaglandin E2 had no significant effect either on basal or IL-1 beta-stimulated mRNA levels. Collagenase was secreted into the media and showed minimal gelatinolytic activity at 36-h stimulation with IL-1 beta by zymography. By Western immunoblotting, we demonstrated with 24 h of stimulation the secretion of the active form of collagenase, which further increased after 36 h with IL-1 beta compared with the control. When RMC were retreated with genistein and herbimycin A, both inhibited collagenase mRNA induction by IL-1 beta. These data suggest that IL-1 beta stimulates interstitial collagenase synthesis and activation and that a tyrosine kinase pathway is involved in the signal transduction mechanisms and is not dependent on endogenous prostaglandin biosynthesis. Recently, a third interstitial collagenase (collagenase-3) has been identified from breast carcinoma. This cDNA is 84% identical to the rat interstitial collagenase cDNA probe we have utilized in this study and thus may represent the rat homologue of the human collagenase-3 now called matrix metalloproteinase (MMP)-13.
 ...
PMID:Interleukin-1 beta induces interstitial collagenase gene expression and protein secretion in renal mesangial cells. 859 77

Vascular endothelial growth factor (VEGF) is a potent and specific mitogen for endothelial cells. VEGF is synthesized and secreted by many differentiated cells in response to a variety of stimuli including hypoxia. VEGF is expressed in a variety of tissues as multiple homodimeric forms (121, 165, 189, and 206 amino acids/monomer) resulting from alternative RNA splicing. VEGF121 is a soluble mitogen that does not bind heparin; the longer forms of VEGF bind heparin with progressively higher affinity. The higher molecular weight forms of VEGF can be cleaved by plasmin to release a diffusible form(s) of VEGF. We characterized the proteolysis of VEGF by plasmin and other proteases. Thrombin, elastase, and collagenase did not cleave VEGF, whereas trypsin generated a series of smaller fragments. The isolated plasmin fragments of VEGF were compared with respect to heparin binding, interaction with soluble VEGF receptors, and ability to promote endothelial cell mitogenesis. Plasmin yields two fragments of VEGF as indicated by reverse phase high performance liquid chromatography and SDS-polyacrylamide gel electrophoresis: an amino-terminal homodimeric protein containing receptor binding determinants and a carboxyl-terminal polypeptide which bound heparin. Amino-terminal sequencing of the carboxyl-terminal peptide identified the plasmin cleavage site as Arg110-Ala111. A heterodimeric form of VEGF165/110, was isolated from partial plasmin digests of VEGF165. The carboxyl-terminal polypeptide (111-165) displayed no affinity for soluble kinase domain region (KDR) or Fms-like tyrosine kinase (FLT-1) receptors. The various isoforms of VEGF (165, 165/110, and 121) bound soluble kinase domain region receptor with similar affinity (approximately 30 pM). In contrast, soluble FLT-1 receptor differentiated VEGF isoforms (165, 165/110, 110, and 121) with apparent affinities of 10, 30, 120, and 200 pM, respectively. Endothelial cell mitogenic potencies of VEGF110 and VEGF121 were decreased more than 100-fold compared to that of VEGF165. The present findings indicate that removal of the carboxyl-terminal domain, whether it is due to alternative splicing of mRNA or to proteolysis, is associated with a significant loss in bioactivity.
 ...
PMID:The carboxyl-terminal domain (111-165) of vascular endothelial growth factor is critical for its mitogenic potency. 863 22

TNF-alpha inhibits collagen synthesis and at high concentrations stimulates collagenase synthesis in fibroblasts. As fluid from chronic inflammatory lesions contains significant levels of TNF-alpha, it is puzzling why these lesions exhibit dense accumulations of disorganized collagen. In this study we determined if low concentrations of TNF-alpha may inhibit the collagen phagocytic pathway in fibroblasts and thereby contribute to fibrosis. Collagen phagocytosis was measured by flow cytometric assessment of internalized, fluorescent collagen beads. TNF-alpha induced a dose-dependent reduction (optimal dose: 40% at 10 ng/ml; p<0.001) in the proportion of phagocytic cells and a twofold reduction of the number of internalized beads per cell but did not alter the total number of vital cells. TNF-alpha reduced by twofold the degradation of collagen films. Fluid flow shear-force assays demonstrated that TNF-alpha caused a 72% reduction (p < 0.05) in strong binding of collagen-coated beads to cells indicating that TNF-alpha may inactivate receptors and inhibit collagen binding. Furthermore, TNF-alpha reduced cell contact area with collagen substrates by threefold and inhibited reattachment of trypsinized cells by fourfold. Although levels of collagen receptors were increased by TNF-alpha (53% increase in alpha(2) (beta)1 integrin; p<0.001, 20% increase in alpha(1)beta(1)), the receptors were inactivated by the cytokine. The reduced phagocytic activity of TNF-alpha-treated cells was restored to control levels by treatment with the integrin-activating Abs A16G6 and JBS2. TNF-alpha inhibited focal adhesion formation and phosphotyrosine staining in focal adhesions. These effects were replicated by the tyrosine kinase inhibitor genistein, which also inhibited phagocytosis. Collectively, these data indicate that TNF-alpha inhibits adherence and phagocytosis of collagen. These effects are mediated by a reduction in the strength of alpha(2)beta(1) integrin binding to collagen, possibly through tyrosine kinases in focal adhesions. At low concentrations of TNF-alpha (10 ng/ml) that are found in the periphery of chronic inflammatory lesions, we suggest that inhibition of the collagen phagocytic pathway may contribute to fibrosis.
 ...
PMID:TNF-alpha inactivation of collagen receptors: implications for fibroblast function and fibrosis. 866 7

Matrix metalloproteinases participate in normal physiologic processes; however, their overproduction has been associated with connective tissue destruction in a variety of pathological states. Migrating basal keratinocytes transiently express collagenase-1 during normal cutaneous reepithelialization. However, the overexpression of both collagenase-1 and stromelysin-1 has been associated with the pathogenesis of chronic nonhealing ulcers. Aberrant expression of metalloproteinases in inflammation is mediated, at least in part, by soluble factors. Since hepatocyte growth factor/scatter factor (HGF/SF) has been reported to promote keratinocyte migration and proliferation, key events in wound repair, and since HGF/SF is produced by dermal fibroblasts and its c-Met receptor is expressed by basal keratinocytes in wounded skin, we have studied the effects of HGF/SF upon keratinocyte metalloproteinase expression. We have found that HGF/SF can stimulate keratinocyte collagenase-1 and stromelysin-1 production in a dose-dependent and matrix-dependent manner. Expression of 92-kDa gelatinase was not affected by HGF/SF. We determined that HGF/SF regulation of collagenase-1 expression is transcriptionally mediated and requires tyrosine kinase and protein kinase C activaties. HGF/NK1, a naturally occurring, truncated form of HGF/SF, also stimulates collagenase-1 production, but much less efficiently than does the parent molecule. However, HGF/NK2, another HGF/SF splice variant, as well as heparin, potently inhibit HGF/SF-induced collagenase-1 synthesis. These results indicate that HGF/SF and its naturally occurring splice variants have diverse biological effects on keratinocytes and suggest an additional mechanism whereby HGF/SF may regulate keratinocyte function during wound repair.
 ...
PMID:Mechanisms of hepatocyte growth factor stimulation of keratinocyte metalloproteinase production. 879 21

Incubation of cultured neonatal rat cardiomyocytes in hypoxic conditions, mimicking the deprivation of O2 which occurs during in situ myocardial ischemia, leads to a progressive change in cardiomyocytes cytoskeletal components. Confocal scanning laser immunofluorescence microscopy (CSLIM) reveals that the typical striated costameric distribution of vinculin gradually disappears to be replaced by circular, vinculin-containing sarcolemmal rosettes. There is little change in distribution of vinculin in the focal adhesions or in the intercalated disks. This cytoskeletal alteration, like that observed in virally transformed fibroblasts and phorbol ester-treated skeletal myoblasts, is inhibited by genistein, a tyrosine kinase inhibitor. Increased exposure to hypoxic conditions also produces an increase in a 92-kDa collagenase which is immunolocalized only to cardiomyocytes. As with the rosette formation, genistein also inhibits the increased expression of the 92-kDa collagenase. We suggest that this cytoskeletal change with attendant release of 92 kDa collagenase may represent a defensive mechanism on the part of the cardiomyocyte to reduce damage by reducing the cellular coupling to the extracellular collagenous matrix, thereby lessening the stresses imposed by contractile forces.
 ...
PMID:Hypoxia-induced alterations in cytoskeleton coincide with collagenase expression in cultured neonatal rat cardiomyocytes. 882 74


1 2 3 4 5 Next >>