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

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.
 ...
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 zinc-dependent endopeptidases which are secreted from cells as zymogens and can be activated by treatment with organomercurial reagents or limited proteolysis. The proenzyme forms of MMP-2 (gelatinase A) and MMP-9 (gelatinase B) are found in complex with tissue inhibitor of metalloproteinases (designated proMMP-2/ TIMP-2 and proMMP-9/TIMP-1, respectively). The proposed mechanism of activation by mercurial compounds involves the induction of a conformational change in the zymogen which leads to propeptide autoprocessing. To investigate the possibility of conformational differences in MMPs, solute quenching of MMP intrinsic fluorescence was used to probe the relative exposure of tryptophan residues in latent and mercurial-activated MMPs. Our data demonstrate that fluorescence quenching of the proMMP-2/TIMP-2 complex by either acrylamide or iodide is significantly increased following mercurial activation. In contrast, no significant change in tryptophan accessibility accompanies mercurial treatment of either proMMP-2 or TIMP-2 alone, or mercurial-activated MMP-2 mixed with TIMP-2. To determine whether the enhanced fluorescence quenching was unique to the activated proMMP-2/TIMP-2 complex, similar experiments were performed using MMP-1, MMP-3, and MMP-9/TIMP-1 complex. In all cases, both latent and mercurialtreated MMPs exhibited similar fluorescence quenching profiles, suggesting that there are no significant conformational differences between the zymogen and activated forms of MMP-1, -2, -3, or -9/TIMP-1. The enhanced fluorescence quenching observed with mercurial-treated proMMP-2/TIMP-2 is indicative of increased exposure of a previously buried tryptophan residue(s), providing evidence for a structural rearrangement of the activated complex. These data, together with our previous biochemical observation that mercurial treatment of proMMP-2/TIMP-2 exposes the MMP-2 active site without propeptide processing (Y. Itoh et al. (1995) Biochem. J. 308, 645-651), suggest that the activated proMMP-2 in the complex may represent a transitional conformational intermediate in MMP activation.
 ...
PMID:Fluorescence quenching studies of matrix metalloproteinases (MMPs): evidence for structural rearrangement of the proMMP-2/TIMP-2 complex upon mercurial activation. 880 67

In neurodegenerative disease or after brain injury, parenchymal cells in the central nervous system are activated to produce inflammatory mediators, mainly consisting of cytokine-induced factors, in a manner similar to, but clearly different from a peripheral inflammatory response. The upregulated expression of several extracellular matrix proteins in astrocytes located surrounding a neuritic plaque in Alzheimer's disease is a good example of such a response. A family of mediators which is cytokine-induced during an inflammatory response in the periphery are the matrix metalloproteinases. Matrix metalloproteinases are calcium-requiring, zinc-containing endopeptidases that constitute a major component of the enzyme cascade responsible for degradation of extracellular matrix proteins such as collagen, proteoglycan and laminin. Little is known about the cellular source or the function of matrix metalloproteinases in the central nervous system or how their expression is regulated in brain. Thus, it was of interest to determine which factors of the so-called 'brain inflammatory response' regulate the expression of these proteases in the nervous system. To this end, we measured the expression of matrix metalloproteinases in cultured rat astrocytes and microglia after treatment with various cytokines. Interleukin-1 beta, tumor necrosis factor-alpha and lipopolysaccharide were potent stimulators of matrix metalloproteinase-2 (gelatinase A) and matrix metalloproteinase-9 (gelatinase B) in cultured rat astrocytes; the effect of each secretagogue was inhibited in the presence of glucocorticoid. Interleukin-1 beta and lipopolysaccharide also stimulated the production of matrix metalloproteinase-3 (stromelysin-1) in astrocytes. In addition, activated microglia release matrix metalloproteinase-9. The 'coactivator' of monocytic phagocytes, interferon-gamma, rather than augmenting the response to lipopolysaccharide, inhibited it. Thus, cytokines appear to be potent regulators of matrix metalloproteinase production in astrocytes and microglia. The presence of these enzymes in 'inflamed' central nervous system may suggest their involvement in the pathogenesis or progression of neurodegenerative diseases which are associated with an inflammatory component. Much remains to be learned about the potential substrates for these enzymes and the mechanism of their activation in the central nervous system.
 ...
PMID:Regulation of matrix metalloproteinase expressions in astrocytes, microglia and neurons. 894 20

Matrix metalloproteinases (MMPs) are a family of Zn2+ endopeptidases that are expressed in many inflammatory conditions and that contribute to connective tissue breakdown and the release of the pro-inflammatory cytokine tumour necrosis factor-alpha (TNF-alpha). There is emerging evidence that MMPs have a role in inflammatory disorders of the central nervous system (CNS) such as multiple sclerosis. However, little is known about the expression of MMPs by inflamed tissue within the CNS or by the glia, neurones, and leucocytes which participate in the inflammatory response. To address this issue we have developed a polymerase chain reaction (PCR)-based method for the quantitation of rat MMP mRNA levels, which we have applied to astrocyte cultures with and without inflammatory stimulation. The technique relies on a competition reaction in which a synthetic standard cDNA is co-amplified with the target cDNA in the same PCR reaction. Standard multi-competitor cDNAs, containing priming sites for nine MMPs, and two housekeeping genes were constructed. We have shown that MMP activity is increased over three-fold in neonatal rat astrocyte cultures following stimulation with lipopolysaccharide (LPS). At the mRNA level, MT-MMP-1, 72 kDa gelatinase, and stromelysin-3 were constitutively expressed and unaffected by LPS treatment, whereas 92 kDa gelatinase, and stromelysin-1 were strongly induced (1,000-fold). Stromelysin-2, rat collagenase, and macrophage metalloelastase were modestly upregulated by LPS treatment. Matrilysin was not expressed. This technique is suitable for quantifying MMP expression in the cells which contribute to inflammation in the CNS and could also be applied directly to tissue samples from animal models of disease.
 ...
PMID:Quantitation of matrix metalloproteinases in cultured rat astrocytes using the polymerase chain reaction with a multi-competitor cDNA standard. 897 1

The binding properties of the COOH-terminal hemopexin-like domain (C domain) of human gelatinase A (matrix metalloproteinase-2, 72-kDa gelatinase) were investigated to determine whether the C domain has binding affinity for extracellular matrix and basement membrane components. Recombinant C domain (rC domain) (Gly417-Cys631) was expressed in Escherichia coli, and the purified protein, identified using two antipeptide antibodies, was determined by electrospray mass spectrometry to have a mass of 25,925 Da, within 0.1 Da of that predicted. As assessed by microwell substrate binding assays and by column affinity chromatography, the matrix proteins laminin, denatured type I collagen, elastin, SPARC (secreted protein that is acidic and rich in cysteine), tenascin, and MatrigelTM were not bound by the rC domain. Unlike the hemopexin-like domains of collagenase and stromelysin, the rC domain also did not bind native type I collagen. Nor were native or denatured types II, IV, V, and X collagen, or the NC1 domain of type VII collagen bound. However, binding to heparin and fibronectin (Kd, 1.1 x 10(-6) M) could be disrupted by 0.58-0.76 and 0.3 M NaCl, respectively. Using nonoverlapping chymotrypsin-generated fragments of fibronectin, binding sites for the rC domain were found on both the 40-kDa heparin binding and the 120-kDa cell binding fibronectin domains (Kd values, approximately 4-6 x 10(-7) M). The Ca2+ ion, but not the potential structural Zn2+ ion, were found to be essential for maintaining the binding properties of the protein. The apo-form of the rC domain did not bind heparin, and both ethylenediaminetetraacetic acid and the specific Ca2+ ion chelator 1, 2-bis(2-aminophenoxy) ethane-N,N,N',N'-tetraacetic acid, but not the Zn2+ ion chelator 1,10-phenanthroline, eluted the holo form of the rC domain from both heparin-Sepharose and fibronectin. Inductive coupled plasma mass spectrometry also did not detect a Zn2+ ion in the rC domain. In contrast, reduction with 65 mM dithiothreitol did not interfere with heparin binding, further emphasizing the crucial structural role played by the Ca2+ ion. Together, these data demonstrate for the first time that the hemopexin-like domain of gelatinase A has a binding site for fibronectin and heparin, and that Ca2+ ions are important in maintaining the structure and function of the domain.
 ...
PMID:The hemopexin-like domain (C domain) of human gelatinase A (matrix metalloproteinase-2) requires Ca2+ for fibronectin and heparin binding. Binding properties of recombinant gelatinase A C domain to extracellular matrix and basement membrane components. 905 49

Matrix metalloproteinases represent a family of zinc-dependent proteolytic enzymes thought to be involved in normal and disease-related tissue remodeling processes. Increasing information about these enzymes is becoming available concerning their primary sequences, regulation at the mRNA level, activation of proenzymes, and modulation of enzyme activity by tissue inhibitors. In contrast, their morphological distribution and biological functions in normal tissues are poorly understood. In the present report, the comparative distribution of five members (gelatinase-A, gelatinase-B, matrilysin, stromelysin-1, and stromelysin-3) of the matrix metalloproteinase family and of one inhibitor (TIMP-1) has been morphologically analyzed in human liver and skin with the aid of new monospecific antibodies. Because of their common designation as matrix proteinases, these enzymes might have been expected to be distributed throughout these tissues, or at least in the connective tissue. However, each member of the family produces a highly specific pattern, staining structures such as arteriolar smooth muscle cells, myoepithelial cells in secretory portions or the luminal lining in excretory ducts of dermal sweat glands, liver bile canaliculi, or structures surrounding peripheral nerve axons. No reactivity is detected in rat tissues.
 ...
PMID:Differential distribution of five members of the matrix metalloproteinase family and one inhibitor (TIMP-1) in human liver and skin. 918 12

Matrix metalloproteinases (MMPs) are zinc endopeptidases that are required for the degradation of extracellular matrix components during normal embryo development, morphogenesis and tissue remodelling. Their proteolytic activities are precisely regulated by endogenous tissue inhibitors of metalloproteinases (TIMPs). Disruption of this balance results in diseases such as arthritis, atherosclerosis, tumour growth and metastasis. Here we report the crystal structure of an MMP-TIMP complex formed between the catalytic domain of human stromelysin-1 (MMP-3) and human TIMP-1. TIMP-1, a 184-residue protein, has the shape of an elongated, contiguous wedge. With its long edge, consisting of five different chain regions, it occupies the entire length of the active-site cleft of MMP-3. The central disulphide-linked segments Cys 1-Thr 2-Cys 3-Val 4 and Ser 68-Val 69 bind to either side of the catalytic zinc. Cys 1 bidentally coordinates this zinc, and the Thr-2 side chain extends into the large specificity pocket of MMP-3. This unusual architecture of the interface between MMP-3 and TIMP-1 suggests new possibilities for designing TIMP variants and synthetic MMP inhibitors with potential therapeutic applications.
 ...
PMID:Mechanism of inhibition of the human matrix metalloproteinase stromelysin-1 by TIMP-1. 928 70

Modifications around the dipeptide-mimetic core of a hydroxamic acid based matrix metalloproteinase inhibitor were studied. These variations incorporated a variety of natural, unnatural, and synthetic amino acids in addition to modifications of the P1' and P3' substituents. The results of this study indicate the following structural requirements: (1) Two key hydrogen bonds must be present between the enzyme and potent substrates. (2) Potent inhibitors must possess strong zinc-binding functionalities. (3) The potential importance of the hydrophobic group at position R3 as illustrated by its ability to impart greater relative potency against stromelysin when larger hydrophobic groups are used. (4) Requirements surrounding the nature of the amino acid appear to be more restrictive for stromelysin than for neutrophil collagenase, 72 kDa gelatinase, and 92 kDa gelatinase. These requirements may involve planar fused-ring aryl systems and possibly hydrogen-bonding capabilities.
 ...
PMID:Matrix metalloproteinase inhibitors: a structure-activity study. 945 44

By exploiting the thiol function of L-cysteine as a chelating group of the active-site zinc atom of matrix metalloproteinases (MMPs), N- and C-terminal derivatization of this amino acid with aliphatic and aromatic groups allowed us to explore the selectivity of the S and/or S' binding subsites of human neutrophil collagenase (MMP8) and stromelysin (MMP3). With N-benzyloxycarbonyl-L-cysteine-(2-phenyl)ethylamide a submicromolar inhibitor of MMP8 was discovered.
 ...
PMID:Non-peptidic cysteine derivatives as inhibitors of matrix metalloproteinases. 946 46

Human pro-matrix metalloproteinase 3 (proMMP-3) lacking the N-terminal 34 amino acids and the C-terminal hemopexin-like domain was expressed in E. coli and used to investigate the process of proenzyme activation and its interaction with an endogenous inhibitor TIMP-1 during activation. The truncated precursor was purified from the E. coli extract in the presence of 5mM EGTA. The active 23.5 kDa form was generated simply by exposure to Ca2+ and Zn2+ but not either by Ca2+ alone or by Zn2+ alone. The rate of MMP-3(deltaC) formation was concentration dependent, indicating that autoactivation is a bimolecular reaction. The truncated precursor was able to interact with the N-terminal domain of TIMP-1 without losing the 48 residue-long propeptide. However, upon a longer incubation, the propeptide was slowly processed, indicating that the association of the N-terminally truncated proMMP-3 with TIMP-1 is weaker than that of the fully activated MMP-3 and TIMP-1. These results indicate that the expression of MMP activities is regulated by endogenous inhibitor TIMPs during their activation processes which provide an additional control mechanism of extracellular matrix breakdown.
 ...
PMID:Expression of human pro-matrix metalloproteinase 3 that lacks the N-terminal 34 residues in Escherichia coli: autoactivation and interaction with tissue inhibitor of metalloproteinase 1 (TIMP-1). 952 70


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>