Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.24.11 (CD10)
 9,792 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The activation of procollagenase and prostromelysin by mechanisms that might be functional in vivo has been investigated. Studies with cell monolayers plated onto collagen films have indicated key roles for plasmin and TIMP in these processes. Prostromelysin activation could be rapidly effected by fibroblast monolayers in the presence of plasminogen, with identical kinetics to plasminogen-streptokinase generated plasmin. Procollagenase activation by plasmin was shown to be poor, although an M(r) shift of 11,000 occurred. Activation was enhanced ten-fold by the presence of active stromelysin even at a very low molar ratio. A tumour cell line secreting procollagenase but not stromelysin was found to be dependent upon the addition of both stromelysin and plasminogen to effect degradation of collagen films. Biochemical studies of metalloproteinase activation were carried out using other purified proteinases synthesized by connective tissue cells including endopeptidase 24.11, endopeptidase-2, cathepsin B and cathepsin L. None was a particularly effective activator relative to plasmin, but cathepsin B was shown to activate stromelysin. By use of both cell model systems and biochemical studies of purified enzymes we have found that the role of plasmin as the major metalloproteinase activator in normal connective tissue cells remains unchallenged.
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PMID:Physiological mechanisms for metalloproteinase activation. 148 31

Inflammation of the periodontium leads to connective tissue degradation and eventual tooth loss. The regulation of matrix metalloproteinases (MMPs) has been studied to determine their role in these processes and also during tissue remodelling. Analysis of gingival crevicular fluid has revealed the presence of collagenase and gelatinase that, in the acute stages of periodontal disease, are derived predominantly from polymorphonuclear leukocytes. These MMPs appear to be intimately associated with tissue destruction since the levels of the active forms of these enzymes obtained from either crevicular fluid or mouthrinse samples correlate with tissue destruction and, therefore, provide a sensitive means of demonstrating disease activity. Transforming growth factor-beta, an important regulator of connective tissue remodelling, has been implicated in the rapid remodelling of periodontal tissues. TGF-beta promotes tissue matrix formation by stimulating both the synthesis of matrix proteins (collagen, fibronectin and SPARC) and proteinase inhibitors (TIMP, PAI-1) and by decreasing the synthesis of MMPs, but not the 72 kDa-gelatinase. Nuclear run-on analyses have shown that TGF-beta reduces collagenase and stromelysin synthesis by suppressing gene transcription without altering mRNA stabilities. In contrast, the transcription of the gelatinase and TIMP genes was increased by TGF-beta, which also increased gelatinase mRNA stability. Remodelling of alveolar bone involves interaction between osteoblasts and osteoclasts. Osteoblasts, under the influence of osteotropic hormones (vit D3, PTH and retinoic acid), produce MMPs which appear to function in the removal of soft tissue that precludes access of osteoclasts to the mineralized tissue surface. Rat osteoblastic cells produce MMPs with activity on native collagen, native collagen 3/4-fragments and gelatin and, in addition, two forms of TIMP activity. The 3/4-collagen endopeptidase, purified to apparent homogeneity, also has significant collagenase and gelatinase activities and an amino terminal sequence almost identical to human 72 kDa-gelatinase. The production of this enzyme was stimulated by TGF-beta, which suppresses bone resorption, and by osteotropic hormones which stimulate bone resorption, supporting a bifunctional role for the gelatinase in connective tissue remodelling. Although there is strong evidence for the involvement of MMPs in the resorption of bone and in the inflammation-mediated destruction of periodontal tissues, the role of MMPs in the remodelling of mature soft connective tissues remains equivocal.
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PMID:Matrix metalloproteinases in periodontal tissue remodelling. 148 60

The neutral zinc metalloendopeptidase (NEP, EC 3.4.24.11) is an integral membrane protein found in brain tissue, polymorphonuclear leukocytes, and many epithelia. We show here that NEP is expressed on rabbit synovial fibroblasts and on simian virus 40 (SV40) DNA- and H-ras-transformed rabbit mammary epithelial cells. Treatment of these cells with 12-O-tetradecanoylphorbol-13-acetate (TPA) for 24 h decreased expression of NEP mRNA transcripts and decreased the biosynthetically labeled immunoprecipitable NEP antigen. In contrast to its effects on NEP, TPA treatment induced expression of the secreted metalloproteinase collagenase and the tissue inhibitor of metalloproteinases. TPA induced stromelysin, another secreted metalloproteinase, only in the fibroblasts. These data provide evidence that the expression of the membrane-bound NEP is regulated in several cell types.
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PMID:Phorbol diesters regulate expression of the membrane neutral metalloendopeptidase (EC 3.4.24.11) in rabbit synovial fibroblasts and mammary epithelial cells. 254 98

To elucidate structure-function relationships of stromelysin-3, a putative matrix metalloproteinase originally identified at the tumor-stromal cell interface in breast carcinomas, the human cDNA was expressed in mammalian cells, and its products were isolated and characterized. In stably transfected cells, stromelysin-3 was recovered as a complex mixture of species ranging in size from approximately 20 to 65 kDa. Among these products, a major 45-kDa species with an N terminus of Phe98 and an intact C-terminal domain was identified as a true endopeptidase on the basis of its ability to cleave the bait region of alpha 2-macroglobulin between Phe684 and Tyr685, a site identical to that recognized by stromelysin-1. However, unlike stromelysin-1 or other members of the matrix metalloproteinase family, the mature form of stromelysin-3 was unable to hydrolyze a range of extracellular matrix molecules associated with either the basement membrane or interstitium. To probe for alternate substrates among tumor cell-derived products, purified stromelysin-3 was incubated with [35S]methionine-labeled medium conditioned by the breast cancer cell line, MCF-7. Under these conditions, a single, tumor cell-derived protein was hydrolyzed as assessed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography. Following anion-exchange chromatography and preparative gel electrophoresis, the stromelysin-3 substrate was identified by N-terminal sequencing as the serine proteinase inhibitor, alpha 1-proteinase inhibitor. Further studies demonstrated that stromelysin-3 rapidly destroyed the antiproteolytic function of alpha 1-proteinase inhibitor by cleaving the antiproteinase at a distinct site between Ala350 and Met351 within the reactive-site loop. Together, these data not only demonstrate that human stromelysin-3 acts as a powerful endopeptidase with a restricted substrate specificity distinct from all other matrix metalloproteinases, but also serve to identify serine proteinase inhibitors as potential physiologic targets at sites of extracellular matrix remodeling.
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PMID:Hydrolytic inactivation of a breast carcinoma cell-derived serpin by human stromelysin-3. 752 94

Stromelysin-1, matrix metalloproteinase-3 (MMP-3), is an important endopeptidase selectively expressed by somatic cells in organ tissues. The renal tubulointerstitium, for example, comprises tubular epithelium and interstitial fibroblasts forming the principal mass of the kidney. We observed that mRNA encoding stromelysin-1 is detectable in murine renal fibroblasts, but not in proximal tubular epithelium. Transcripts measured by RNase protection assay in renal fibroblasts increase following exposure to phorbol ester, and thereafter, activated stromelysin-1 protein can be detected in culture media by Western blotting. A 6.4 Kb genomic clone containing the putative stromelysin-1 promoter was isolated and a relevant 2.1 Kb PstI restriction fragment including 2.1 Kb of the immediate 5'-flanking region was sequenced on both strands. Two transcriptional start sites were identified by primer extension; the major start site corresponded to a previously established position in the rat promoter, and a second undescribed minor transcriptional start site was located 16 bp upstream of the primary site. A HiNF-A chromatin-activating element at -106 bp was found in the early promoter region of pR336 and an active AP-1 site at -72 bp with an Ets/PEA-3 motif at -203 bp was suggested by transient transfection of luciferase minigenes into renal fibroblasts responsive to phorbol ester. This Ets element was identical to a site in the early promoter of the fibroblast-specific gene FSP1. A baseline enhancement in activity of pR336 in fibroblasts was further observed with the addition of 5' flanking sequence out to -1980 bp. This additional region of flanking sequence contains two modular regions: one of multiple PEA-3 elements between -684 bp and -1955 bp and a second region between -1929 bp and -1980 bps containing a second AP-1 site at -1929 bp, a MBF-1/ MEP-1 metal binding site, and a PPAR peroxisome proliferator element at -1950 bp. Our findings implicate a gene structure with expected activity in a mesenchymal phenotype. The PKC-dependent regulation of the stromelysin-1 gene supports the notion that it may be modulated during inflammation or tissue remodeling.
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PMID:Identification of promoter activity and differential expression of transcripts encoding the murine stromelysin-1 gene in renal cells. 921 54

PD 069185 is a highly selective and structurally novel inhibitor of endothelin converting enzyme-1 (ECE-1). PD 069185 is a trisubstituted quinazoline with an IC50 value of 0.9 +/- 0.1 microns for inhibition of human ECE-1 from the solubilized membrane fraction of CHO cells stably transfected with human ECE-1 cDNA. Kinetic analysis revealed that PD 069185 is best fit with a competitive inhibition model with a Ki value of 1.1 +/- 0.1 microns and binds in a reversible manner. The closely related enzyme, ECE-2, is not inhibited at up to 100 microns PD 069185. In addition, PD 069185 at 200-300 microns has little effect on other metalloproteases, such as neutral endopeptidase 24.11, stromelysin, gelatinase A, and collagenase, showing a high ECE-1 specificity. Data are also presented to show that this series of inhibitors are effective in inhibiting ECE-1 in intact cells and in attenuating the increase in perfusion pressure induced by big ET-1 in isolated rat mesentery. These non-peptidic ECE-1 inhibitors should serve as a valuable tool to study the pathophysiological role of endothelin and the therapeutic potential of ECE-1 inhibitors.
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PMID:Novel selective quinazoline inhibitors of endothelin converting enzyme-1. 947 2

A three-dimensional model of the 507-749 region of neutral endopeptidase-24.11 (NEP; E.C.3.4.24.11) was constructed integrating the results of secondary structure predictions and sequence homologies with the bacterial endopeptidase thermolysin. Additional data were extracted from the structure of two other metalloproteases, astacin and stromelysin. The resulting model accounts for the main biological properties of NEP and has been used to describe the environment close to the zinc atom defining the catalytic site. The analysis of several thiol inhibitors, complexed in the model active site, revealed the presence of a large hydrophobic pocket at the S1' subsite level. This is supported by the nature of the constitutive amino acids. The computed energies of bound inhibitors correspond with the relative affinities of the stereoisomers of benzofused macrocycle derivatives of thiorphan. The model could be used to facilitate the design of new NEP inhibitors, as illustrated in the paper.
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PMID:A three-dimensional construction of the active site (region 507-749) of human neutral endopeptidase (EC.3.4.24.11). 1019 85

The peptide DHLSDNYTLDHDRAIH (Link N), cleaved from the N-terminus of the link protein component of cartilage proteoglycan aggregates by the action of stromelysin, can act as a growth factor and stimulate synthesis of proteoglycans and collagen in articular cartilage [McKenna, Liu, Sansom and Dean (1998) Arthritis Rheum. 41, 157-161]. The mechanism by which this biologically active peptide is degraded and inactivated was investigated using U937 monocytes as a model cell. Time-course experiments showed that two major proteases, an initial serine proteinase followed by a metalloproteinase, acted in sequence. Analysis of the resulting fragments showed that the serine endopeptidase cleavage was at the Leu(3)-Ser(4) bond to produce the peptide SDNYTLDHDRAIH. The terminal serine could then be removed from the resulting peptide by an aminopeptidase. A second metallopeptidase liberated the peptides SDNYTL or DNYTL from DHDRAIH by cleavage at the Leu(9)-Asp(10) bond. The DNYTL peptide intermediate was degraded too rapidly to allow sequencing and sequential aminopeptidase cleavages removed further amino acids from the N-terminus of the remaining DHDRAIH peptide. The identical patterns of breakdown that occurred when either whole cells or purified plasma membranes were used indicated that proteolysis and inactivation of Link N was carried out entirely by membrane-associated enzymes.
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PMID:Link peptide cartilage growth factor is degraded by membrane proteinases. 1088 Mar 46

Matrix metalloproteinases (MMP) are a family of zinc-dependent enzymes which degrade various components of the extracellular matrix (ECM) and play an important role in facilitating neoplastic cell invasion and metastasis. Structural changes in the extracellular matrix are necessary for cell migration during tissue remodeling and tumor invasion. Expression of MMP-2, -3, -9, -10, and -13 was investigated in both spontaneous and xenografted (cells derived from an established cell-line [DAOY#3]) childhood medulloblastomas (MEDs)/primitive neuroectodermal tumors (PNETs) employing an indirect alkaline phosphatase conjugated immunocytochemical technique. Evaluation of the results was based on (a) the percent of neoplastically transformed tissue that reacted positively and (b) a measure of staining intensity [graded from A (highest) to D]. The two forms of stromelysin (SL), types 1 (MMP-3) and 2 (MMP-10), share 82% sequence homology, but exhibit differences in cellular synthesis and inducibility by cytokines and growth factors in vitro. Strong overall expression of MMP-3 and -10 was found only in the spontaneous MEDs/PNETs, especially in the ECM adjacent to blood vessels. Positive immunoreactivity could be seen for these two MMPs in the ECM surrounding over 90% of the neoplastically transformed cells in the spontaneous cases, and the staining intensity was also the strongest possible (A,B). Focal (surrounding less than 10% of the neoplastically transformed cells) but strong (A,B) immunoreactivity for collagenase-3 (MMP-13) was also only detected in spontaneous MEDs/PNETs, an endopeptidase characterized by a potent degrading activity against a wide spectrum of substrates. Weak (surrounding anywhere between 10% and 90% of the neoplastically transformed cells, and of B and B,C intensity) expression of MMP-2 (gelatinase A) and MMP-9 (gelatinase B), two cytokine-induced MMPs, was also observed in the spontaneous cases. Staining for MMP-2 was negative in the xenografted MEDs/PNETs. The only positive immunoreactivity in the xenografted MEDs/PNETs was observed in the case of MMP-9, with expression of strong intensity in the ECM surrounding over 90% of the neoplastically transformed xenografted MED/PNET cells (++++; A,B). It is clear that the activation of MMPs and their inhibitors occurs in a very well orchestrated manner. The data presented here suggest that there are significant differences in the pathophysiology of spontaneous and xenografted human neoplasms, which further establishes the already detected limitations of such models in preclinical cancer research.
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PMID:Significant differences in the matrix metalloproteinase expression profiles of spontaneous medulloblastomas/primitive neuroectodermal tumors as compared with their xenografted, established tumor cell line derived counterparts. 1121 45

The matrix metalloproteinases (MMPs) are a family of enzymes that degrade the extracellular matrix (ECM) and are considered to be important in neoplastic cell invasion and metastasis. Structural changes in the extracellular matrix are necessary for cell migration during tissue remodeling and neoplastic invasion. Expression of MMP-2, -3, -9, -10, and -13 was investigated in human childhood medulloblastomas (MEDs)/primitive neuroectodermal tumors (PNETs) employing an indirect alkaline phosphatase conjugated immunohistochemical antigen detection technique. Evaluation of the results was based on (a) the percent of neoplastically transformed tissue that reacted positively and (b) a measure of immunoreactivity or staining intensity [graded from A (highest) to D (negative)]. Strong overall expression of MMP-3 and -10 was found in MEDs/PNETs, especially in the ECM adjacent to blood vessels. Positive immunoreactivity was identified for these two MMPs in the ECM surrounding over 90% of the neoplastically transformed cells with the staining intensity being also the strongest possible (A,B). These two forms of stromelysin (SL), types 1 (MMP-3) and 2 (MMP-10), share 82% sequence homology, but exhibit differences in cellular synthesis and inducibility by cytokines and growth factors in vitro. Focal (surrounding less than 10% of the neoplastically transformed cells) but strong (A,B) immunoreactivity was determined for collagenase-3 (MMP-13), an endopeptidase characterized by a potent degrading activity against a wide spectrum of substrates. Weak (surrounding anywhere between 10% and 90% of the neoplastically transformed cells, and of B and B,C intensity) expression of MMP-2 (gelatinase A) and MMP-9 (gelatinase B), two cytokine-induced MMPs, was also observed. It is clear that the activation of MMPs and their inhibitors occurs in a very well orchestrated manner. The necessity of these same enzymes for the extravasation and infiltration of lymphocytes into regions of chronic local inflammation, as associated with neoplastically transformed masses of cells, may aid the transformed cells which have already acquired a more aggressive, metastatic immunophenotype (IP) to enter the peripheral circulation. Further characterization of the expression and utilization of MMPs and their inhibitors in the progression of solid human malignancies should lead to the development of novel anti-cancer therapies.
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PMID:Matrix metalloproteinase expression in childhood medulloblastomas/primitive neuroectodermal tumors. 1121 44


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