Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.6.4 (chondroitinase)
 2,039 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Mast cells are widely distributed in perivascular connective tissues, especially in areas of active tumor growth and vascular reactivity. Incubation of metabolically [35S]O4 = -labeled subendothelial extracellular matrix (ECM) with lysates of bone marrow-derived mouse mast cells (BMMC) resulted in extensive degradation of heparan sulfate (HS) into fragments 5 to 6 times smaller than intact HS side chains. A much lower activity (seven- to eightfold) was expressed by intact BMMC incubated in contact with the ECM. These fragments were not produced in the presence of heparin, were sensitive to deamination with nitrous acid, and resistant to further degradation with papain or chondroitinase ABC. These results indicate that an endoglycosidase (heparanase) is involved in BMMC-mediated degradation of HS in the subendothelial ECM. Heparanase activity was not detected in medium conditioned by cultured BMMC, or in lysates of Ableson transformed BMMC and rat basophilic leukemic (RBL) cells. Both heparanase and beta-hexosaminidase, a mast cell granule enzyme, were released on degranulation of BMMC induced by the calcium ionophore A23187, or by exposure to IgE-Ag, suggesting that heparanase is localized in the cell granules. Under these conditions, less than 5% of the cellular content of lactate dehydrogenase were released. Degradation of the ECM-HS by the mast cell heparanase and the associated release of HS-bound endothelial cell growth factors that are stored in ECM (Vlodavsky et al, Proc Natl Acad Sci USA 84:2292, 1987; Bashkin et al, Biochemistry 28:1737, 1989) may play a role in the proposed mast cell-mediated stimulation of neovascularization.
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PMID:Degranulating mast cells secrete an endoglycosidase that degrades heparan sulfate in subendothelial extracellular matrix. 169 99

Mouse bone marrow-derived mast cells differentiated in vitro and sensitized with monoclonal IgE respond to antigen-initiated activation with the release of histamine, beta-hexosaminidase, chondroitin sulfate E proteoglycan, and leukotriene C4 (LTC4). The chondroitin sulfate E nature of the glycosaminoglycan side chain was established by demonstrating that the chondroitinase ABC disaccharide digestion products were composed of equal quantities of 4-sulfated and 4,6-disulfated N-acetyl-galactosamine. The single immunoreactive sulfidopeptide leukotriene, released and quantitated with a class-specific antibody, was identified as LTC4 by its retention time on reverse-phase high-performance liquid chromatography and by its specific spasmogenic activity on the guinea pig ileum. The release of the preformed mediators, as well as of LTC4, was related in a dose-response fashion to the concentration of monoclonal IgE used during the sensitization step and to the concentration of specific antigen used to initiate the activation-secretion response. The optimal concentrations of IgE for sensitization and of antigen for challenge were the same for the release of preformed mediators and of LTC4. In addition, the time courses of their release were superimposable, with a plateau at 5 min after antigen challenge. The release of three preformed mediators and of LTC4 after fixation of IgE, washing of the sensitized cells, and antigen challenge unequivocally indicates a bone marrow-derived mast cell origin for these products. Linear regression analyses of the net percent release of beta-hexosaminidase to histamine and of 35S-chondroitin sulfate E to beta-hexosaminidase yielded straight lines that intersected at the origin, which indicates that the three preformed mediators are localized in the secretory granules of the bone marrow-derived mast cells. The concomitant generation of 23 ng of LTC4/10(6) sensitized bone marrow-derived mast cells represents the first example of IgE-dependent release of substantial amounts of LTC4, a component of slow reacting substance of anaphylaxis, from a mast cell population of greater than 95% purity. The IgE-dependent generation of LTC4, rather than prostaglandin D2, by the chondroitin sulfate E proteoglycan-containing bone marrow-derived mast cells contrasts with the predominant generation of prostaglandin D2 by heparin proteoglycan-containing mast cells. These differences together support the existence of two phenotypically different mast cell subclasses.
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PMID:IgE-mediated release of leukotriene C4, chondroitin sulfate E proteoglycan, beta-hexosaminidase, and histamine from cultured bone marrow-derived mouse mast cells. 618 39

Mouse mast cells were differentiated and grown by culturing bone marrow cells in medium containing 2 X 10(-10) M purified interleukin 3 (IL 3). The cells obtained were similar in ultrastructure, membrane antigen phenotype, proteoglycan type, and lipid products generated upon immunologic activation to mast cells differentiated in culture by WEHI-3-conditioned medium (WEHI-3-CM) and by concanavalin A (Con A) splenocyte-conditioned medium. Phenotypically, these cells expressed IgE receptors and H-2 antigens and were recognized by a monoclonal antibody (B23.1) that did not react with mouse serosal heparin-containing mast cells. The classic phenotypic markers of mouse T cells or macrophages were not detected. The mouse mast cells differentiated with IL 3 as well as those differentiated in WEHI-3-CM incorporated [35S]sulfate into a nonheparin proteoglycan of 150,000 to 200,000 m.w. Most of the 35S-labeled macromolecules were degraded by chondroitinase ABC to yield only two disaccharides, which co-chromatographed on ascending thin layer chromatography with delta Di-4S and delta Di-diSE; thus, the proteoglycan in these cells is composed of chondroitin sulfate E glycosaminoglycans. After sensitization with monoclonal IgE, washing, and antigen activation, the IL 3 differentiated cells released the preformed mediator beta-hexosaminidase and generated and released two major classes of lipid mediators. The quantities of leukotriene C4 (LTC4), leukotriene B4 (LTB4), and platelet-activating factor (PAF-acether) generated/10(6) cells were 17, 3.0, and 3.1 ng, respectively. The ratio of these three lipid mediators was similar to that obtained from mast cells differentiated in WEHI-3-CM and in Con A-conditioned medium. Thus, T cell-derived IL 3 is the component present in the conditioned media that is required for differentiation and growth of the subclass of mast cells containing chondroitin sulfate E proteoglycan, designated E-MC. The IL 3-dependent E-MC may represent the in vitro counterpart of the T-cell-dependent mucosal mast cell, suggesting in turn that the production of LTC4 and LTB4 and of PAF-acether may play a role in adaptive intestinal immunity to helminthic parasites.
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PMID:Interleukin 3: A differentiation and growth factor for the mouse mast cell that contains chondroitin sulfate E proteoglycan. 619 93

The catabolism of dermatan sulfate (DS) commences with endohydrolysis of the polysaccharide to oligosaccharides by proposed endo-beta-N-acetylhexosaminidase and endohexuronidase activities. To investigate the substrate specificities of these activities, we developed an assay to measure specific products of their action upon oligosaccharide substrates. Tetra- to tetradecasaccharides, rich in glucuronic acid (GlcA) or iduronic acid (IdoA), were obtained from chondroitinase ABC digests of chondroitin sulfate (CS)-A and DS, respectively, separated by gel-filtration chromatography and characterized by electrospray ionization-tandem mass spectrometry (ESI-MS/MS). Endo-beta-N-acetylhexosaminidase and endohexuronidase cleavage of these oligosaccharides was then assessed by incubating with cell homogenate (source of endoglycosidase activity) and measuring di- to octasaccharide products derived from the nonreducing end of the substrate by ESI-MS/MS. We found that both activities preferentially degraded the GlcA-rich substrate, with minor activity toward the IdoA-rich substrate and that a minimum of four and five monosaccharides were required on the reducing side of the target glycosidic linkage for endo-beta-N-acetylhexosaminidase and endohexuronidase cleavage, respectively. Thus, the minimum-sized substrates were a hexasaccharide for endo-beta-N-acetylhexosaminidase and an octasaccharide for endohexuronidase. We observed that endo-beta-N-acetylhexosaminidase sequentially removed tetrasaccharides from the nonreducing end of oligosaccharides when unrestricted by substrate length, whereas endohexuronidase activity was random and comparatively low. The activities displayed acidic pH optima and were shown by subcellular fractionation to reside in lysosomes and late endosomes. We suggest that these activities represent the known Hyal-1 and endo-beta-glucuronidase enzymes and that these enzymes act in concert to degrade GlcA-rich domains of DS but are less active toward regions containing IdoA.
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PMID:Minimum substrate requirements of endoglycosidase activities toward dermatan sulfate by electrospray ionization-tandem mass spectrometry. 1882 60