Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.24.23 (MMP)
 4,246 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The latent precursor of matrilysin (EC 3.4.24.23; punctuated metalloproteinase (PUMP) was purified from transfected mouse myeloma cell conditioned medium and was found to contain one zinc atom per molecule which was essential for catalytic activity. Promatrilysin could be activated to the same specific activity by (4-aminophenyl)mercuric acetate, trypsin, and incubation at elevated temperatures (heat activation). Active matrilysin hydrolyzed the fluorescent substrate 2,4-dinitrophenyl-Pro-Leu-Gly-Leu-Trp-Ala-D-Arg-NH2 at the Gly-Leu bond with a maximum value for kcat/Km of 1.3 x 10(4) M-1 s-1 at the pH optimum of 6.5 and pKa values of 4.60 and 8.65. Activity is inhibited by the tissue inhibitor of metalloproteinases-1 in a 1:1 stoichiometric interaction. Analysis by sodium dodecyl sulfate polyacrylamide gel electrophoresis in conjunction with N-terminal sequencing revealed that, as with all other matrix metalloproteinases similarly studied, promatrilysin activation was accompanied by the stepwise proteolytic removal of an M(r) 9000 propeptide from the N-terminus. The intermediates generated were dependent on the mode of activation used but, in all cases studied, activation terminated with an autocatalytic cleavage at E77-Y78 to yield the final M(r) 19,000 active matrilysin. From an analysis of the stability of the various intermediates, we propose that the sequence L13-K33 is particularly important in protecting the E77-Y78 site from autocatalytic cleavage, thereby maintaining the latency of the proenzyme.
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PMID:Biochemical characterization of matrilysin. Activation conforms to the stepwise mechanisms proposed for other matrix metalloproteinases. 139 Jun 35

A small metalloproteinase that digests Azocoll was found in the uterus of the rat. Its activity increased to high levels during the postpartum period in parallel with the breakdown of the extracellular matrix exclusive of collagen (Sellers, A., and Woessner, J.F., Jr. (1980) Biochem. J. 189, 521-531). This enzyme has now been purified almost 7,000-fold to homogeneity from 12 g of tissue using molecular sieve chromatography, blue sepharose chromatography, and zinc-chelate chromatography. Gel electrophoresis with sodium dodecyl sulfate and dithiothreitol gives Mr = 28,000 for the latent form of the enzyme and Mr = 19,000 for the active form that arises spontaneously or by treatment with aminophenylmercuric acetate. The enzyme digests components of the extracellular matrix including gelatins of types I, III, IV, and V, fibronectin, and proteoglycan. It digests the alpha 2(I) chain of gelatin in preference to the alpha 1(I) chain and cleaves dinitrophenyl-Pro-Leu-Gly-Ile-Ala-Gly-Pro-D-Arg. It cleaves the B chain of insulin at two points: Ala14-Leu15 and Tyr16-Leu17. It has no action on collagens of types I, III, IV, or V at 26 degrees C and no action on elastin or phenylazo-Pro-Leu-Gly-Pro-D-Arg. The pH optimum is at pH 7 and the pI at 5.9. The enzyme requires zinc and calcium ions for activity; cobalt and strontium can partially replace these metal ions. The enzyme is not inhibited by low levels of phosphoramidon or Zincov. Its properties clearly distinguish it from collagenase, gelatinase (matrix metalloproteinase 2), and stromelysin (matrix metalloproteinase 3); it therefore constitutes a further member of the family of extracellular matrix metalloendopeptidases. The name matrix metalloproteinase 7 is proposed.
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PMID:Purification and properties of a small latent matrix metalloproteinase of the rat uterus. 318 22

Previous studies from our laboratory have demonstrated that the administration of alpha-tocopheryl hemisuccinate (TS), but not unesterified alpha-tocopherol (T), protects hepatocytes from a variety of toxic insults including chemicals, drugs, metals, and oxidative stress. One possible mechanism for this unique cytoprotection is that succinate released from cellular TS is used as a supplemental energy source during a toxic challenge. To test this hypothesis, we examined the effect of TS (25 microM) administration on cell viability, lipid peroxidation, and several cellular energy-related processes such as mitochondrial membrane potential (MMP, psi delta), lactate formation, and ATP and K+ concentrations in isolated hepatocyte suspensions during a toxic challenge with the alkylating agent, ethyl methanesulfonate (EMS). Data from these studies demonstrate that EMS treatment results in rapid cell death and lipid peroxidation following 2 h of incubation. Preceding EMS-induced cell death was a rapid loss of MMP, intracellular ATP and K+ levels, and mitochondrial ultrastructure as well as a transient increase in cellular lactate production. Pretreatment of hepatocytes with TS prior to EMS exposure prevented the loss of MMP and mitochondrial ultrastructural changes as well as lipid peroxidation and cell death. Cellular ATP levels and lactate production did not reflect the protection afforded to TS-treated hepatocytes. Protection against EMS-induced toxicity was not observed when hepatocytes were: (i) pretreated with TS and esterase inhibitors (preventing T and succinate release from TS); (ii) pretreated with other lipophilic succinate derivatives (cholesteryl hemisuccinate, monomethyl and dimethyl succinate); or (iii) pretreated with T and sodium succinate. Unlike monomethyl succinate, cytoprotective TS pretreatment did not stimulate gluconeogenesis or glycolysis. Hepatocytes isolated from rats pretreated for 24 h with T were not protected from the toxic effects of EMS, unlike TS-pretreated rats. In conclusion, TS cytoprotection against the mitochondrial toxicant EMS appears to be related to the hepatocellular accumulation of TS and the maintenance of mitochondrial function (MMP). Based on our earlier findings and the present observations, we propose that a unique subcellular disposition for TS and the subsequent release of T and succinate at a critical mitochondrial site is responsible for the observed cytoprotection.
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PMID:Role of cellular energy status in tocopheryl hemisuccinate cytoprotection against ethyl methanesulfonate-induced toxicity. 818 15

ConA-induced cell surface activation of pro-matrix metalloproteinase-2 (pro-MMP-2) by MDA-MB-231 human breast cancer cells is apparently mediated by up-regulation of membrane type 1 MMP (MT1-MMP) through transcriptional and posttranscriptional mechanisms. Here, we have explored the respective roles of cell surface clustering and protein tyrosine phosphorylation in the ConA-induction effects. Treatment with succinyl-ConA, a variant lacking significant clusterability, partially stimulated MT1-MMP mRNA and protein levels but did not induce MMP-2 activation, suggesting that clustering contributes to the transcriptional regulation by ConA but appears to be critical for the nontranscriptional component. We further found that genistein, an inhibitor of tyrosine phosphorylation, blocked ConA-induced pro-MMP-2 activation and ConA-induced MT1-MMP mRNA level in a dose-dependent manner, implicating tyrosine phosphorylation in the transcriptional aspect. This was confirmed by the dose-dependent promotion of pro-MMP-2 activation by sodium orthovanadate in the presence of suboptimal concentrations of ConA (7.5 microg/ml), with optimal effects seen at 25 microg/ml orthovanadate. Genistein did not inhibit the ConA potentiation of MMP-2 activation in MCF-7 cells, in which transfected MT1-MMP is driven by a heterologous promoter, supporting the major implication of phosphotyrosine in the transcriptional component of ConA regulation. These data describe a major signaling event upstream of MT1-MMP induction by ConA and set the stage for further analysis of the nontranscriptional component.
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PMID:Tyrosine phosphorylation mediates ConA-induced membrane type 1-matrix metalloproteinase expression and matrix metalloproteinase-2 activation in MDA-MB-231 human breast carcinoma cells. 937 97

The effect of AMPA-receptor stimulation on MMP and on the concentration of intracellular calcium ([Ca2+]i) was studied in dissociated CGC from rat pups, by flow cytometry. In the presence of cyclothiazide, AMPA induced a sodium-independent decrease in MMP up to 30.7+/-2.5%. This effect was antagonized by CNQX and NBQX. Mepacrine and dibucaine reversed the effect of AMPA on MMP, suggesting that it is mediated by a release of arachidonic acid. AMPA alone induced a slight (about 7%) increase in [Ca2+]i. In the presence of cyclothiazide, AMPA induced a concentration-dependent [Ca2+]i increase up to 29.10+/-2.10% that was not reversed by flunarizine. This increase was similar to that observed in a Na+-free medium, and was antagonized by CNQX and NBQX, but not by MK-801. Mitochondria play a key role in the modulation of [Ca2+]i since a significant [Ca2+]i increase was found in the presence of FCCP. On the other hand, the dantrolene-sensitive calcium pools do not participate in the [Ca2+]i increase induced by stimulation of AMPA receptors. It is concluded that when AMPA-receptor desensitization is blocked, a decrease in MMP and an increase in [Ca2+]i occurs, which could be additional events to potentiate neuronal cell death induced by glutamate.
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PMID:Flow cytometric study of mitochondrial dysfunction after AMPA receptor activation. 966 17

The current article describes a new assay to measure thiopurine methyltransferase (TPMT) activity from red blood cells. This method is based on the measurement of the reaction product 6-methylmercaptopurine (6-MMP) by high-performance liquid chromatography (HPLC). 6-MMP is extracted by ethyl acetate with recoveries of 85%, 80%, 80%, and 92% for 50, 250, 500, and 1,000 ng/100 microL packed red blood cells, respectively. 6-MMP was identified and measured by a Zorbax CN column installed in an HPLC system. The chromatograms were resolved using a mobile phase consisting of 40 mmol/L sodium phosphate buffer (pH 3) and methanol in a gradient from 1% to 20% of methanol. Under these conditions 6-MMP is well resolved from substrates (6-mercaptopurine and S-adenosyl-L-methionine) and endogenous peaks. When the TPMT activity from 20 patients was measured by the HPLC-linked assay and the classic radiochemical method, a linear correlation was obtained between both procedures ( y = 0.99x + 0.33; x-axis, radiochemical assay; y-axis, HPLC-linked assay; r = 0.98). In conclusion, the current report describes a new, reliable, safe, and nonradioactive method to measure TPMT activity that is shorter and simpler than the previously described ones.
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PMID:Determination of thiopurine methyltransferase activity in human erythrocytes by high-performance liquid chromatography: comparison with the radiochemical method. 1159

The Wnt signaling pathway modulates the transcription of genes linked to proliferation, differentiation and tumor progression. beta-Catenin-Tcf (BCT)-dependent Wnt signaling is influenced by the short-chain fatty acid sodium butyrate, which induces growth arrest and/or maturation of colonic carcinoma cells. We have compared the effects of sodium butyrate on BCT-dependent signaling in 2 colon carcinoma cell lines that differ in their physiologic response to butyrate, with SW620 cells responding to butyrate by undergoing terminal differentiation and apoptosis, and HCT-116 cells undergoing reversible growth arrest, but no significant apoptotic cell death. Furthermore, these colon carcinoma cell lines differ in their mechanism of Wnt pathway activation, with adenomatous polyposis coli (APC) mutant SW620 cells having high levels of BCT complexes and APC wild-type HCT-116 cells having mutant beta-catenin, low levels of BCT complexes and correspondingly higher levels of free Tcf. We have demonstrated that in SW620 cells, butyrate downregulates BCT-dependent expression of the Tcf-TK, matrilysin and cyclin D1 promoters, whereas in HCT-116 cells, butyrate upregulates expression of these promoters. Cotransfection with expression vectors that interfere with the Wnt pathway suggests that butyrate enhances BCT complex-DNA binding. Butyrate reduces the expression of Tcf4 in HCT-116 cells, consistent with the induction by butyrate of Tcf-repressible promoters in these cells. These findings indicate that sodium butyrate modulates the Wnt pathway in SW620 and HCT-116 cells in a different manner and that these differences have consequences for promoter activity that may influence the physiologic response to butyrate.
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PMID:Cell type- and promoter-dependent modulation of the Wnt signaling pathway by sodium butyrate. 1177 42

Activation of cell surface components has been implicated in the activation of downstream signaling cascade in response to UV irradiation, and yet the identity and the interaction of those components have been scantly documented. Accumulating evidence indicates that caveolae encapsulating caveolins is the location for those interactions. We found in cultured human keratinocytes that UV irradiation induced both caveolin-1 and EGFR phosphorylation. Filipin, a caveolae disruptive agent, inhibited UV-induced caveolin-1 activation. Na+-K+-ATPase catalyzes active transport of Na+ and K+ across plasma membrane of mammalian cells, inactivation of which has recently been shown to be involved in the activation of signal transduction pathways including MAP kinase cascade. We found in this study that UV inactivated Na+-K+-ATPase in time-dependent manner, Na+-K+-ATPase activity started to decrease 5 min post UV irradiation and reduced to 60% of its original activity within 1 h. Pretreatment with Flipin and MMP inhibitor recovered Na+-K+-ATPase activity lost by UV irradiation. ECIS analysis indicated that both EGF treatment and UV irradiation increased membrane electric activity which was inhibited by MMP inhibitor and Filipin. Further study showed that pretreatment of human keratinocytes with MMP inhibitor or Filipin inhibited UV-induced phosphorylation of p38 and JNK, which was however not observed in LnCap cells, a prostate cancer cell line lacking caveolin-1. UV irradiation also induced ectodomain shedding of HB-EGF in a time-dependent manner in keratinocytes. Collectively, we conclude that UV-induced MAP kinase activation is mediated by cell surface receptor activation due to the matrix activity and membrane caveolae function and inactivation of Na+-K+-ATPase.
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PMID:Extracellular matrix activity and caveolae events contribute to cell surface receptor activation that leads to MAP kinase activation in response to UV irradiation in cultured human keratinocytes. 1575 25

An oral administration of a single dose of beta-adrenoceptor agonist clenbuterol (15 mg/kg body weight) to mice resulted in an increased collagen distribution in the subendocardium and myocardium of the left ventricle. Abundant collagen accumulation is characteristic in myonecrotic regions and around blood vessels. Hydroxyproline assay and sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) of pepsin insoluble collagen confirmed this stimulated collagen proliferation. An MMP-activity assay of tissue extract by gelatin in gel zymography demonstrated a significant inhibition of MMP-9 activity in the beta-agonist-treated group. The results suggest that clenbuterol treatment is capable of inducing structural and functional remodeling of the extracellular matrix by down-regulating MMP-9 activity and thereby causing an impairment of collagen turnover. This may lead to changes in the different hemodynamic properties of the tissue, including ventricular compliance.
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PMID:Beta-adrenoceptor agonist clenbuterol down-regulates matrix metalloproteinase (MMP-9) and results in an impairment of collagen turnover in mice left ventricle. 1607 24

To study the role of hydrogen sulfide (H2S) in hypoxic pulmonary vascular structural remodeling (HPVSR), a total of 24 Wistar rats were randomly divided into three groups: control group (n = 8), hypoxia group (n = 8) and hypoxia with sodium hydrosulfide (hy + NaHS) group (n = 8). The mean pulmonary artery pressure (mPAP), plasma H2S and the percentage of muscularized arteries (MA), partially muscularized arteries (PMA) and nonmuscularized arteries (NMA) in small pulmonary vessels were measured. Collagen I and III, elastin, transforming growth factor-beta3 (TGF-beta3), proliferative cell nuclear antigen (PCNA) and human urotensin II(U-II) expressions were detected by immunohistochemical assay. The mRNA expressions of procollagen I and III, matrix metalloproteinase-1 (MMP-1) and tissue inhibitor of metalloproteinease-1 (TIMP-1) were detected by in situ hybridization. The results showed that NaHS significantly increased plasma H2S, decreased mPAP and the percentage of MA and PMA of small pulmonary vessels in rats under hypoxia. Meanwhile, NaHS inhibited the proliferation of pulmonary artery smooth muscle cells (PASMCs) represented by a decrease in the expressions of PCNA and human U-II in pulmonary artery wall. NaHS reduced the expression of collagen I and III, elastin and TGF-beta3 protein and decreased the expressions of procollagen I and III mRNA in pulmonary arteries of rats under hypoxia, but it did not impact the ratio of TIMP-1 mRNA to MMP-1mRNA in pulmonary arteries of rats under hypoxia. These data suggested that H2S played an important role in the development of HPVSR.
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PMID:Effects of hydrogen sulfide on hypoxic pulmonary vascular structural remodeling. 1625 22


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