Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.24.17 (MMP-3)
 3,419 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have set up a quantitative and sensitive enzymatic assay for proteases of different classes acting on proteoglycans, casein, or gelatin. Radiolabeled substrates were covalently attached to insoluble microcarriers and assays were performed in 96-well plates. Protease activities were determined by the release of labeled degradation products. Time- and dose-response curves were linear when the solubilization of labeled substrates did not exceed 15-20% of the initially bound molecules. Results were compared to those from zymographic analyses on proteoglycan-, gelatin-, and casein-polyacrylamide gels, as well as to the results obtained with conventional assays using soluble [3H]-casein and [3H]gelatin. Our assay procedure was more sensitive than other available methods: it detected picogram amounts of trypsin as well as picogram or nanogram amounts of the purified human matrix metalloproteinases, MMP-1, MMP-2, MMP-3, and MMP-9, depending on the specific activities of these MMPs on the different substrates. Our new procedure was appropriate for assaying the MMPs present in crude culture media conditioned by chondrocytes cultivated under various conditions.
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PMID:An assay for matrix metalloproteinases and other proteases acting on proteoglycans, casein, or gelatin. 812 75

The processing of synovial fluids of patients suffering from rheumatoid arthritis led to the characterization of a neutral metalloproteinase with polymorphonuclear leukocyte progelatinase and polymorphonuclear leukocyte procollagenase activating properties. The activator exhibits a relative molecular mass of M(r) 27,000 and is an active form of stromelysin. Thus, it reacts specifically with antibodies raised against human stromelysin, splits polymorphonuclear leukocyte progelatinase in a manner characteristic of stromelysin, and is inhibited by EDTA as well as by a tissue inhibitor of metalloproteinases (TIMP-2). The activator shows a high specificity for the matrix metalloproteinases, polymorphonuclear leukocyte progelatinase and polymorphonuclear leukocyte procollagenase. It shows only weak hydrolysis of casein and gelatin, and it does not activate fibroblast M(r) 72,000 progelatinase. Brief treatment with trypsin does not lead to a significant change in the activator's relative molecular mass, but induces a rapid loss of its activating activity for polymorphonuclear leukocyte progelatinase, while its proteolytic activity against the synthetic substrate, N-(2,4)-dinitrophenyl-Pro-Gln-Gly-Ile-Ala-Gly-Gln-D-Arg, is increased about 3-fold. The same tryptic treatment does not affect the activator's proteolytic activity towards casein and gelatin.
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PMID:A trypsin sensitive stromelysin isolated from rheumatoid synovial fluid is an activator for matrix metalloproteinases. 829 62

The stromelysin-2 (SL-2) gene is transcriptionally active in normal human keratinocytes and encodes a secreted, catalytically competent but latent matrix metalloproteinase. Phorbolester induction resulted in the emergence of SL-2 (but not SL-1 transcripts), whereas the opposite was true for human mucosal fibroblasts. Expression of keratinocyte SL-2 was also induced by the two keratinocyte growth factors, transforming growth factor-alpha and epidermal growth factor, by the proinflammatory cytokine, tumor necrosis factor-alpha, but, somewhat surprisingly, not by interleukin-1 beta. The latent SL-2 proenzyme was isolated from 12-O-tetradecanoylphorbol-13-acetate-induced keratinocytes by immunoaffinity chromatography using a cross-reactive antibody raised against human SL-1. This procedure led to the recovery of a single M(r) 54,000 molecular species at a level of approximately 0.2 microgram/ml of culture medium. Amino-terminal sequencing identified the protein as SL-2 and verified the predicted signal sequence cleavage site. Conformational activation of latent SL-2 precursor by SDS gave rise to a full-length, uncleaved (M(r) 54,000) active form and at the same time exposed a cryptic thiol group. By contrast, organomercurial activation resulted in autolytic truncation of the molecule with loss of M(r) approximately 10,000 propeptide. SL-2 shared with (human fibroblast) SL-1 the ability to cleave casein, to "superactivate" fibroblast type procollagenase, and to form apparently binary, SDS-resistant complexes with tissue inhibitor of metalloproteinases-1.
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PMID:Cell type-specific regulation of SL-1 and SL-2 genes. Induction of the SL-2 gene but not the SL-1 gene by human keratinocytes in response to cytokines and phorbolesters. 834 17

The relationship of enzyme structure to substrate specificity for the matrix metalloproteinases interstitial collagenase and stromelysin-2 has been investigated by analysis of the cleavage specificity of recombinant human collagenase-stromelysin-2 hybrid proteins and C terminally truncated collagenase and stromelysin-2. Two series of chimeric proteins were devised by progressive substitution of exon-encoded domains. The recombinant proteins were expressed in COS-7 cells as protein A-fusion proteins and purified on an IgG affinity matrix. Treatment with 4-amino-phenylmercuric acetate released active metalloproteinase of the sizes predicted for the chimeric proteins. Active forms of both the chimeric protein series and the short form enzymes expressed both casein- and gelatin-degrading activities. Like stromelysin, the catalytic activity of stromelysin-2 was contained in the N-terminal domain (encoded by exons 1-5) and was apparently independent of the C-terminal domain (encoded by exons 6-10). Only full-length collagenase displayed a triple helicase (collagenolytic) activity; no combination of N- or C-terminal collagenase domains fused with stromelysin-2 domains had such activity. This suggests that the triple helicase activity is a composite of elements derived from both halves of the collagenase molecule. C terminally truncated collagenase (exons 1-5) and a hybrid of collagenase exons 1-5 and stromelysin-2 exons 6-10 cleaved denatured type I collagen (gelatin) to generate diagnostic peptides in gelatin fingerprint assays. When exon 5 (the exon encoding the zinc-binding domain) was derived from stromelysin-2, the enzyme specificity in the fingerprint assay changed to that of native stromelysin-2. In contrast, when exon 5 was derived from collagenase, the specificity reflected that of the parent enzyme. Our data also suggest that mismatching of exons 2 and 5 destabilizes the enzyme, presumably by altering the geometry of the propeptide-zinc-binding site interaction. We conclude that the loss of triple helicase collagenolytic activity is not accompanied by a shift to the broad specificity characteristic of stromelysin. Rather, the zinc-binding domain confers a distinct cleavage specificity on each metalloproteinase.
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PMID:Role of zinc-binding- and hemopexin domain-encoded sequences in the substrate specificity of collagenase and stromelysin-2 as revealed by chimeric proteins. 846 59

The family of matrix metalloproteinases is a family of closely related enzymes that play an important role in physiological and pathological processes of matrix degradation. The most distinctive characteristic of interstitial collagenases (fibroblast and neutrophil collagenases) is their ability to cleave interstitial collagens at a single peptide bond; however, the precise region of the enzyme responsible for this substrate specificity remains to be defined. To address this question, we generated truncated mutants of neutrophil collagenase with various deletions in the COOH-terminal domain and chimeric molecules between neutrophil collagenase and stromelysin and assayed the expressed enzymes against type I collagen and the general substrate, casein. Our data suggest that substrate specificity for interstitial collagen is determined by a 16-aa sequence in the COOH-terminal domain of neutrophil collagenase and is influenced by the integrity of a disulfide-defined loop at the COOH terminus for maximal activity. It was found that a relatively large region of 62-aa residues influenced the relative efficiency of collagenolytic activity. In addition to the region that conferred this specificity, a site at the COOH side of the presumptive zinc-binding locus was found to be necessary for general catalytic activity. Mutation of a critical aspartic residue at position 253 within this area resulted in complete loss of proteolytic activity, suggesting that Asp-253 might function as one of the ligands for divalent cations, which are essential for enzymatic activity.
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PMID:Structure-function relationship of human neutrophil collagenase: identification of regions responsible for substrate specificity and general proteinase activity. 846 63

Wound repair involves many processes including cell migration, provisional matrix deposition, and remodeling. All of these processes are likely to be affected by matrix-modifying enzymes. Members of the matrix metalloproteinases family are physiologic mediators of the extracellular matrix degradation. Within this matrix metalloproteinases family, stromelysins can degrade many components of the extracellular matrix. We therefore tested the hypothesis that stromelysins could be produced by human surface respiratory epithelial (HSRE) cells repairing a wound. Experimental wounds were created in vitro in HSRE cell cultures and in situ in human bronchial mucosa maintained in organ culture. Stromelysin production was measured by casein-gel zymography in cellular protein extracts derived from repairing migratory and nonrepairing stationary cells of wounded HSRE cell cultures. Stromelysin-producing cells present in cell and tissue cultures were localized and characterized using immunofluorescence techniques. Zymographic and immunofluorescence techniques showed that stromelysins were produced exclusively by the migratory HSRE cells. Zymogram analysis showed that stromelysins were overexpressed and overactivated during the wound repair process, with the maximal production observed at wound closure. Using an anti-cytokeratin 14 antibody, we identified stromelysin-3-producing cells as basal epithelial cells. Moreover, most stromelysin-3-producing cells expressed the mesenchymal marker vimentin. Similar to stromelysins localization, vimentin-positive HSRE cells were exclusively located in the wounded area, and they were also positive to cytokeratin 14. In conclusion, stromelysins are suggested to be involved in HSRE cell migration and extracellular matrix remodeling during wound repair. Furthermore, stromelysin production by repairing HSRE cells is linked to the acquisition of a mesenchymal phenotype. HSRE cell migration may then be associated with the shift from an epithelial to a mesenchymal phenotype.
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PMID:Wound repair-induced expression of a stromelysins is associated with the acquisition of a mesenchymal phenotype in human respiratory epithelial cells. 860 Mar 17

Porphyria cutanea tarda is characterized by severe connective tissue damage in sun-exposed skin. The regulated synthesis and degradation of the extracellular matrix by various matrix metalloproteinases (MMPs) determine its amount and composition within the skin. In this study, we therefore asked whether long-wave ultraviolet irradiation (340-450 nm) in conjunction with uroporphyrin I could modulate the synthesis of MMPs with substrate specificities for dermal (collagens I, III, V; proteoglycans) and basement membrane components (collagens IV, VII; fibronectin; laminin) and whether synthesis of the counteracting tissue inhibitor of metalloproteinases is also affected. After irradiation of uroporphyrin-pretreated fibroblasts, specific mRNAs of MMP-1 and MMP-3 increased concomitantly up to 2.7-fold compared with ultraviolet-irradiated cells and up to 10-fold compared with mock-irradiated or uroporphyrin I-treated controls. In contrast, mRNA levels of tissue inhibitor of metalloproteinases remained unaltered. Similar results were obtained by immunoprecipitation. Gelatin and casein zymography revealed increased proteolytic activity of MMP-2 and MMP-3 in blister fluids of patients with porphyria cutanea tarda, indicating that similar events may occur in vivo. Using deuterium oxide as enhancer and sodium azide as quencher of singlet oxygen, we could increase or reduce MMP synthesis, suggesting that singlet oxygen is the major intermediate in the upregulation of MMPs after irradiation of uroporphyrin-pretreated fibroblasts. Taken together, our results show that ultraviolet irradiation alone, and to a greater extent in conjunction with uroporphyrin I, results in an unbalanced synthesis of MMPs that may contribute to the destruction of the dermis and basement membrane, leading to blistering and accelerated photoaging in porphyria cutanea tarda patients.
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PMID:Photosensitization of uroporphyrin augments the ultraviolet A-induced synthesis of matrix metalloproteinases in human dermal fibroblasts. 875 77

Matrix metalloproteinases (MMPs) can be activated in vitro by multiple mechanisms such as treatment with proteases, organomercurials, oxidants, and detergents. The proposed cysteine switch model for activation suggests that these multiple methods for activation cause the dissociation of the single cysteine residue in the propeptide from the active site zinc. In particular, it has been suggested that organomercurials such as 4-aminophenylmercuric acetate (APMA) work by directly reacting with the sulfhydryl group of this cysteine residue, resulting in its displacement from the active site. However, recent data by Chen et al. [(1993) Biochemistry 32, 10289-10295] demonstrated that modification of this cysteine residue in the propeptide of stromelysin-1 by sulfhydryl reagents did not result in an active enzyme as predicted. To investigate the roles that this cysteine residue and the propeptide salt bridge (R74 to D79) might play in the APMA-induced activation of stromelysin-1, we have changed these residues by site-directed mutagenesis. Wild-type stromelysin-1 and the mutants were all expressed at detectable levels using a recombinant vaccinia virus system and determined to be catalytically competent by zymography. The wild-type stromelysin-1 and the cysteine mutants (C75S and C75H) underwent APMA-induced activation as determined by the characteristic reduction in molecular weight associated with activation and by their ability to cleave casein only when activated. On the other hand, mutants R74K, D79A, and C75H/D79A did not undergo APMA-induced activation. These results demonstrate that APMA-induced activation of stromelysin-1 involves protein interactions in addition to those with cysteine-75 in the propeptide and also suggest that the R74 to D79 salt bridge may play a role.
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PMID:APMA (4-aminophenylmercuric acetate) activation of stromelysin-1 involves protein interactions in addition to those with cysteine-75 in the propeptide. 878 May 27

Matrix metalloproteinases (MMPs) are a group of enzymes with the potential to degrade extracellular matrix proteins. One of the MMPs, stromelysin-1 (MMP-3) has been localized to extracellular matrix vesicles in growth plate chondrocyte cultures, suggesting involvement of this enzyme in remodeling of the extracellular matrix during endochondral development, a process which is regulated by the vitamin D metabolites, 1,25-(OH)2D3 and 24,25-(OH)2D3. To determine whether stromelysin-1 is regulated by vitamin D as well, confluent cultures of cells derived from growth zone (GC) and resting zone (RC) rat costochondral cartilage were treated with 1 alpha, 25-(OH)2D3 (1,25) and 24R,25-(OH)2D3 (24,25), respectively, and the effect on stromelysin-1 assessed by casein gel zymography and Western blots. Although stromelysin-1 activity was enriched in the matrix vesicle fraction, only the plasma membrane enzyme was affected by the treatment; 1, 25 and 24,25 caused a marked decrease in plasma membrane stromelysin-1 activity in their target cells. Since plasma membrane protein kinase C (PKC) activity is stimulated by 1,25 and 24,25, we hypothesized that stromelysin-1 activity was regulated by the vitamin D metabolites via PKC-dependent phosphorylation. To test this, membrane fractions (containing endogenous PKC alpha and zeta as well as stromelysin-1) were incubated in the presence of purified rat brain PKC and/or recombinant human (rh) stromelysin-1 and [gamma 32 P]-ATP and anti-stromelysin-1 immunoprecipitates were analyzed by autoradiography and Western blots. Immuno-phospho-stromelysin-1 was localized to a 52-kDa band in the plasma membrane fraction only; no phosphorylation was observed in the matrix vesicle fraction. Selective inhibitors of PKC activity demonstrated that phosphorylation was inhibited by H7 and low concentrations of H8, but not by HA1004, indicating that PKC, not PKA, was responsible. Protein phosphatase 2A1 (PP2A), a serine/threonine-specific phosphatase, selectively removed the radiolabel in a time-dependent manner, providing further support for a PKC-dependent phosphorylation mechanism. Incubation of resting zone cell plasma membranes with 24,25 but not 1, 25, resulted in phosphorylation of stromelysin-1, demonstrating that the nongenomic effect was metabolite-specific. This suggests that this may be one mechanism by which vitamin D metabolites regulate stromelysin-1 activity and that PKC-dependent phosphorylation inhibits the metalloproteinase.
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PMID:Vitamin D3 regulation of stromelysin-1 (MMP-3) in chondrocyte cultures is mediated by protein kinase C. 881 11

In a wide variety of tumor types, the expression of stromelysin 1 which is one of the matrix metalloproteinases (MMPs) has been shown to correlate with tumor invasion. However, little is known about the distribution of stromelysin in human brain tumors. We have previously shown that a correlation exists between the type IV collagenases, tissue inhibitor of metalloproteinase (TIMP)-1 and TIMP-2 transcripts and in vitro invasiveness among 7 human astrocytoma cell lines. In the present study, we analyzed the expression of stromelysin 1 among the same panel of human astrocytoma cell lines and human fibroblasts by northern blot analyses and in situ hybridization. Northern blot analysis demonstrated that SF-126 and U87 MG expressed high level stromelysin 1 transcripts. Following heat shock stimulation, the stromelysin 1 transcript was up-regulated in U87 MG astrocytoma cells. In situ hybridization analysis showed specific intracytoplasmic localization of mRNA for stromelysin in these astrocytoma cell lines. By casein zymography, we have determined that both SF-126 and U87 MG secreted stromelysin 1 protein. We conclude that stromelysin 1 is expressed by certain human astrocytoma cell lines, and this study confirms the importance of continuing to characterize the proteolytic enzyme profile of these tumors to fully understand the molecular mechanisms involved in astrocytoma invasiveness.
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PMID:Expression of stromelysin 1 in human astrocytoma cell lines. 894 93


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