Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:3.1.6.4 (chondroitinase)
2,039 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Immunological and histological methods have been applied to the developing rat embryo to study the distribution of hyaluronectin (HN, a glycoprotein with hyaluronic acid-binding properties) previously shown to be present in the nervous system and in desmoplasias. HN was absent in the morula and the blastula and was first detected in the mesenchyme bordering the neural tube and somites on Day 10, i.e., at a time when hyaluronic acid is already widely dispersed in the mesenchyme. At this stage HN appeared to be closely associated with the basement membrane around the epithelial structures (somites, notochord, ectoderm) whereas the intercellular areas of mesenchyme were less strongly strained. The delineation of basement membranes decreased progressively, while the accumulation of HN increased in the cell-free areas of mesenchyme, giving a continuous, diffuse pattern. Differentiation of mesenchyme into vertebral cartilage and gut smooth muscle was accompanied by a progressive disappearance of HN. Even after streptomyces hyaluronidase or chondroitinase digestion the antigen was not unmasked in these tissues. The results are in agreement with the few observations made in the human. They suggest that HN could play a role, in association with fibronectin and glycosaminoglycans (hyaluronic acid), in the physiology of the embryonic extracellular matrix. HN appeared at a later stage in the embryonic nervous tissue; its distribution was extracellular in areas where both cell migration and proliferation occur.
...
PMID:Expression of hyaluronic acid-binding glycoprotein, hyaluronectin, in the developing rat embryo. 619 26

Several monoclonal antibodies which recognize different antigenic determinants of chondroitin sulfate proteoglycan were used to study chondroitin sulfate proteoglycan biosynthesis in chicken chondrocyte cultures. The intracellular sites of synthesis and processing and extracellular deposition in matrix were localized by double immunofluorescence reactions. One rat monoclonal antibody, S103L , which recognizes an antigenic determinant of the core protein of the chicken cartilage chondroitin sulfate proteoglycan monomer, was used to identify both extracellular chondroitin sulfate proteoglycan and intracellular compartments containing chondroitin sulfate proteoglycan precursors. Intracellular staining with S103L was localized to perinuclear regions, and, in some chondrocytes, to a few other cytoplasmic vesicles as well. When chondrocytes were not fed for several days, intracellular chondroitin sulfate proteoglycan precursors were accumulated in larger compartments distributed throughout the cytoplasm. Polyclonal chondroitin sulfate proteoglycan antibodies displayed similar staining characteristics. In contrast, several of the monoclonal antibodies, including the rat monoclonals S11D and P100D , and the mouse monoclonals 1-B-5, 3-B-3 and 9-A-2, did not recognize native chondroitin sulfate proteoglycan, but reacted only with chondroitinase ABC-digested (and/or hyaluronidase-digested) chondroitin sulfate proteoglycan. These antibodies were particularly useful in the demonstration of the extracellular codistribution of chondroitin sulfate proteoglycan with either type II collagen or fibronectin. In other experiments, the monoclonal antibodies to chondroitin sulfate proteoglycan served to demonstrate that the perinuclear subset of intracellular compartments is uniquely involved in the addition of chondroitin sulfate oligosaccharides to the chondroitin sulfate proteoglycan core protein. Lastly, using the mouse monoclonal 5-D-4, which recognizes keratan sulfate determinants, the perinuclear region was identified as the site for keratan sulfate addition. Results suggest heterogeneity of keratan sulfate synthesis at the level of individual chondrocytes, even for cells apparently containing equivalent amounts of intracellular chondroitin sulfate proteoglycan.
...
PMID:Immunofluorescence studies of chondroitin sulfate proteoglycan biosynthesis: the use of monoclonal antibodies. 620 57

This report describes the biochemical characterization of a novel extracellular matrix component, " myotendinous antigen," which appears early in chick limb morphogenesis at sites connecting developing muscle fibers, tendons, and bone ( Chiquet , M., and D. Fambrough , 1984; J. Cell Biol., 98:1926-1936). This extracellular matrix antigen is a major component of the secretory proteins released into the medium by fibroblast and muscle cultures; the soluble form is characterized here. This form of myotendinous antigen is a large glycoprotein complex consisting of several disulfide linked subunits (Mr approximately 150,000-240,000). The differently sized antigen subunits are related, since they yielded very similar proteolytic cleavage patterns. M1 antibody can bind to the denatured subunits. The antigen subunits, as well as a Mr approximately 80,000 pepsin-resistant antigenic domain derived from them, are resistant to bacterial collagenase. Despite possessing subunits similar in size to fibronectin, myotendinous antigen appears to be both structurally and antigenically unrelated to fibronectin or to other known extracellular matrix components. About seven times more M1 antigen per cell nucleus was released into the medium in fibroblast as compared to muscle cultures. In muscle conditioned medium, myotendinous antigen is noncovalently complexed to very high molecular weight material that could be heavily labeled by [3H]glucosamine and [35S]sulfate. This material is sensitive to chondroitinase ABC and hence appears to contain sulfated glycosaminoglycans. We speculate that myotendinous antigen might interact with proteoglycans on the surface of muscle fibers, thereby acting as a link to tendons.
...
PMID:Chick myotendinous antigen. II. A novel extracellular glycoprotein complex consisting of large disulfide-linked subunits. 620 99

Proteins with affinities for specific glycosaminoglycans (GAC's) were used as probes for testing the potential of cell surface GAG's to mediate cell adhesive responses to extracellular matrices (ECM). Plasma fibronectin (FN) and proteins that bind hyaluronate (cartilage proteo-glycan core and link proteins) or heparan sulfate (platelet factor 4 [PF4]) were adsorbed to inert substrata to evaluate attachment and spreading of several 3T3 cell lines. Cells failed to attach to hyaluronate-binding substrata. The rates of attachment on PF4 were identical to those on FN; however, PF4 stimulated formation of broad convex lamellae but not tapered cell processes fibers during the spreading response. PF4-mediated responses were blocked by treating the PF4-adsorbed substratum with heparin (but not chondroitin sulfate), or alternatively the cells with Flavobacter heparinum heparinase (but not chondroitinase ABC). Heparinase treatment did not inhibit cell attachment to FN but did inhibit spreading. Cells spread on PF4 or FN contained similar Ca2+-independent cell-substratum adhesions, as revealed by EGTA-mediated retraction of their substratum-bound processes. Microtubular networks reorganized in cells on PF4 but failed to extend into the broadly spread lamellae, where fine microfilament bundles had developed. Stress fibers, common on FN, failed to develop on PF4. These experiments indicate that (a) heparan sulfate proteoglycans are critical mediators of cell adhesion and heparan sulfate-dependent adhesion via PF4 is comparable in some, but not all, ways to FN-mediated adhesion, (b) the uncharacterized and heparan sulfate-independent "cell surface" receptor for FN permits some but not all aspects of adhesion, and (c) physiologically compatible and complete adhesion of fibroblasts requires binding of extracellular matrix FN to both the unidentified "cell surface" receptor and heparan sulfate proteoglycans.
...
PMID:Cell surface heparan sulfate mediates some adhesive responses to glycosaminoglycan-binding matrices, including fibronectin. 621 15

Ruthenium red was used to stain microfibrils in rat aorta after incubation of the tissues with or without one of the enzymes trypsin, collagenase, phospholipase C, chondroitinase ABC, hyaluronidase or neuraminidase, or the reducing agent dithiothreitol. Microfibrils exhibiting periodicity of ruthenium red binding were associated with elastic laminae and collagen fibrils and appeared to attach these structures to each other as well as to basal lamina. Microfibrils in rat and human aorta demonstrated fibronectinlike immunoreactivity, therefore fibronectin may be a component of aorta microfibrils and important in the architecture of blood vessels.
...
PMID:Microfibrils in the aorta. 622 39

We have previously shown that in confluent human fibroblast cultures chondroitin sulfate proteoglycan is a component of the fibronectin-containing pericellular matrix fibers. In the present work the distribution of chondroitin sulfate was studied in subconfluent cell cultures using antibodies that bind to a chemically defined carbohydrate fragment of chondroitinase ABC-modified chondroitin sulfate proteoglycan. Using immunofluorescence microscopy, we observed, in addition to the fibrillar matrix staining, chondroitin sulfate diffusely distributed at the cell surface. In indirect immunoferritin electron microscopy this staining corresponded to patchy binding of ferritin close (24 nm) to the outer aspect of the plasma membrane. The patchy organization appeared uniform in all cell surfaces. The cell surface chondroitin sulfate could not be removed from the plasma membrane by agents that dissociate electrostatic interactions. These data show that in fibroblasts chondroitin sulfate is a component of the outer aspect of the plasma membrane, and raise the possibility of an integral plasma membrane chondroitin sulfate proteoglycan.
...
PMID:Chondroitin sulfate at the plasma membranes of cultured fibroblasts. 641 15

Corneal epithelial cells from 15-day chick embryos produce a fibronectin-rich extracellular matrix when cultured on glass, plastic and fibronectin-coated substrata. Cell culture in the presence of Streptomyces hyaluronidase or chondroitinase ABC resulted in considerable reduction of the matrix; collagenase had a lesser effect but nevertheless also reduced the matrix. In all enzyme treatments the cells attached and spread to form characteristic epithelial cell islands, but the marginal cells of these islands showed a marked reduction in the number of lamellipodia and focal contacts. Also, the immunofluorescent staining pattern for fibronectin was considerably reduced. Control cells cultured on a fibronectin-coated surface were able to reorganize the fibronectin into fibrils, whereas cells cultured in enzymes showed little or no ability to do so. The cellular reorganization of fibronectin could also be inhibited by the addition of L-azetidine-2-carboxylic acid (LACA), an inhibitor of collagen secretion. Cells plated out in the presence of LACA spread much better on collagen substrata than on plastic, glass or fibronectin. However, in all cases very little fibronectin matrix was detectable in the epithelial islands. The results suggest that components of the extracellular matrix (ECM) such as collagen, hyaluronic acid and chondroitin sulphates are not essential for the initial attachment and spreading of corneal epithelial cells in culture, but are important in the development of the ECM, and in maintaining a flattened morphology and spreading behaviour. It is suggested that fibronectin plays an important role in these interactions and that the ability of cells to organize fibronectin into fibrils is dependent on the presence of other ECM components such as glycosaminoglycans and collagen.
...
PMID:Role of glycosaminoglycans and collagen in the development of a fibronectin-rich extracellular matrix in cultured embryonic corneal epithelial cells. 674 72

Both polyvalent and hybridoma-produced antibodies to fibronectin (Fn) were used to 'map' the immunoaccessible subsets of cell surface fibronectin on virus-transformed murine fibroblast SVT2 and rat neuroblastoma B104 cells. As one approach to this end, attachment and spreading responses of cells were measured on tissue culture substrata coated with antibody or with plasma fibronectin to compare their adhesive responses. Both SVT2 and B104 cells adhere poorly to polyvalent anti-Fn-coated substrata over short time intervals, but within several hours changes occur which permit cells to attach and spread as well on anti-Fn as on Fn (post-adsorption of the anti-Fn with Fn also generates a maximal response). This adhesive response could be completely prevented by predigesting the cells with Flavobacterium heparanase, but not with chondroitinase ABC, indicating that the cell surface Fn responsible for antibody-mediated adhesion is associated with heparan sulfate proteoglycans on the cell surface. The compositions of the substratum-attached material (left bound after EGTA-mediated detachment of cells) from cells attaching to anti-Fn or Fn were analysed by SDS-PAGE and found to be identical within the same cell type for the two different substrata. Three hybridoma-produced antibodies, which recognize different determinants on Fn, generated different adhesive responses for SVT2 or B104 cells when adsorbed to the substratum. SVT2 cells adhered well to antibody no. 32-coated substrata but poorly to antibodies 92 or 136; on the other hand, B104 cells responded similarly to all three antibodies over short times of attachment but much better to no. 32 after a several hour incubation. These experiments indicate that (1) much of the cell surface fibronectin is complexed with heparan sulfate proteoglycan and is initially inaccessible to bind to polyvalent antibody on the substratum to promote adhesion; (2) the surface of neuroblastoma cells contains a fibronectin-like molecule which is important in their substratum adhesion; and (3) monoclonal antibodies are valuable tools in 'mapping' the orientation of cell surface molecules like fibronectin by measuring adhesive responses to antibody-coated substrata.
...
PMID:Adhesive responses of fibroblast and neuroblastoma cells to substrata coated with polyvalent or monoclonal antibody to fibronectin. 686 9

We have previously shown that aggregation of microbeads coated with N-CAM and Ng-CAM is inhibited by incubation with soluble neurocan, a chondroitin sulfate proteoglycan of brain, suggesting that neurocan binds to these cell adhesion molecules (Grumet, M., A. Flaccus, and R. U. Margolis. 1993. J. Cell Biol. 120:815). To investigate these interactions more directly, we have tested binding of soluble 125I-neurocan to microwells coated with different glycoproteins. Neurocan bound at high levels to Ng-CAM and N-CAM, but little or no binding was detected to myelin-associated glycoprotein, EGF receptor, fibronectin, laminin, and collagen IV. The binding to Ng-CAM and N-CAM was saturable and in each case Scatchard plots indicated a high affinity binding site with a dissociation constant of approximately 1 nM. Binding was significantly reduced after treatment of neurocan with chondroitinase, and free chondroitin sulfate inhibited binding of neurocan to Ng-CAM and N-CAM. These results indicate a role for chondroitin sulfate in this process, although the core glycoprotein also has binding activity. The COOH-terminal half of neurocan was shown to have binding properties essentially identical to those of the full-length proteoglycan. To study the potential biological functions of neurocan, its effects on neuronal adhesion and neurite growth were analyzed. When neurons were incubated on dishes coated with different combinations of neurocan and Ng-CAM, neuronal adhesion and neurite extension were inhibited. Experiments using anti-Ng-CAM antibodies as a substrate also indicate that neurocan has a direct inhibitory effect on neuronal adhesion and neurite growth. Immunoperoxidase staining of tissue sections showed that neurocan, Ng-CAM, and N-CAM are all present at highest concentration in the molecular layer and fiber tracts of developing cerebellum. The overlapping localization in vivo, the molecular binding studies, and the striking effects on neuronal adhesion and neurite growth support the view that neurocan may modulate neuronal adhesion and neurite growth during development by binding to neural cell adhesion molecules.
...
PMID:The neuronal chondroitin sulfate proteoglycan neurocan binds to the neural cell adhesion molecules Ng-CAM/L1/NILE and N-CAM, and inhibits neuronal adhesion and neurite outgrowth. 751 9

Phosphacan is a chondroitin sulfate proteoglycan produced by glial cells in the central nervous system, and represents the extracellular domain of a receptor-type protein tyrosine phosphatase (RPTP zeta/beta). We previously demonstrated that soluble phosphacan inhibited the aggregation of microbeads coated with N-CAM or Ng-CAM, and have now found that soluble 125I-phosphacan bound reversibly to these neural cell adhesion molecules, but not to a number of other cell surface and extracellular matrix proteins. The binding was saturable, and Scatchard plots indicated a single high affinity binding site with a Kd of approximately 0.1 nM. Binding was reduced by approximately 15% after chondroitinase treatment, and free chondroitin sulfate was only moderately inhibitory, indicating that the phosphacan core glycoprotein accounts for most of the binding activity. Immunocytochemical studies of embryonic rat spinal phosphacan, Ng-CAM, and N-CAM have overlapping distributions. When dissociated neurons were incubated on dishes coated with combinations of phosphacan and Ng-CAM, neuronal adhesion and neurite growth were inhibited. 125I-phosphacan bound to neurons, and the binding was inhibited by antibodies against Ng-CAM and N-CAM, suggesting that these CAMs are major receptors for phosphacan on neurons. C6 glioma cells, which express phosphacan, adhered to dishes coated with Ng-CAM, and low concentrations of phosphacan inhibited adhesion to Ng-CAM but not to laminin and fibronectin. Our studies suggest that by binding to neural cell adhesion molecules, and possibly also by competing for ligands of the transmembrane phosphatase, phosphacan may play a major role in modulating neuronal and glial adhesion, neurite growth, and signal transduction during the development of the central nervous system.
...
PMID:Interactions of the chondroitin sulfate proteoglycan phosphacan, the extracellular domain of a receptor-type protein tyrosine phosphatase, with neurons, glia, and neural cell adhesion molecules. 752 21


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

---