Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.1.53 (sialidase)
 2,694 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Initial adhesion of B16 melanoma variants to non-activated endothelial cells is mediated through specific interaction between GM3 (NeuAc alpha 2----3Gal beta 1----4Glc beta 1----Cer) expressed on melanoma cells and lactosylceramide (LacCer, Gal beta 1----4Glc beta 1----Cer) expressed on endothelial cells. This adhesion is predominant over integrin- or lectin-mediated adhesion in a dynamic flow experimental system employing a parallel plate laminar flow chamber (Lawrence, M. B., Smith, C. W., Eskin, S. G., and McIntire, L. V. (1990) Blood 75, 227-237). In this system, a tumor cell suspension flows over a glass plate coated with glycosphingolipid, lectin, or fibronectin, and adhesion is recorded on videotape. These conditions were designed to mimic the microvascular environment in which tumor metastatic deposition takes place. In contrast, lectin- and fibronectin-based mechanisms are predominant in previously used static adhesion systems. Under static conditions, the relative degree of adhesion of the four B16 variants to endothelial cells or to LacCer-coated plates was the same as their relative degree of GM3 expression (i.e. BL6 approximately F10 greater than F1 greater than WA4), and adhesion was inhibited in the presence of methyl-beta-lactoside, or liposomes containing LacCer or GM3. Adhesion was also inhibited by pretreatment of B16 cells with anti-GM3 antibody DH2 or sialidase and by pretreatment of endothelial cells with anti-LacCer antibody T5A7. Under dynamic flow conditions, WA4 cells did not adhere to mouse endothelial cells at high shear stress (greater than 2.5 dynes/cm2) but did adhere at lower shear stress. In contrast, BL6 and F10 cells adhered strongly at both low and high shear stress. BL6 cell adhesion to endothelial cells at both low and high shear stress was inhibited in the presence of antibody DH2, ethyl-beta-lactoside, or lactose, as well as by pretreatment of BL6 cells with sialidase. Thus, some clear differences, as well as similarities, in cell adhesion under static versus dynamic conditions are demonstrated. These findings suggest that melanoma cell adhesion to endothelial cells, based on GM3/LacCer interaction, initiates metastatic deposition, which may trigger a series of "cascade" reactions leading to activation of endothelial cells and expression of Ig family or selectin receptors, thereby promoting adhesion and migration of tumor cells.
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PMID:Cell adhesion in a dynamic flow system as compared to static system. Glycosphingolipid-glycosphingolipid interaction in the dynamic system predominates over lectin- or integrin-based mechanisms in adhesion of B16 melanoma cells to non-activated endothelial cells. 151 64

The adhesion of HT29 human colon adenocarcinoma cells to different extracellular matrix components was studied. While treatment of the cells with sialidase had no detectable effect on binding to laminin and fibronectin, attachment to collagen IV was decreased. However, additional removal of beta-(1-4)-bound galactose led to significantly reduced binding to all of the substrates, including fibronectin and laminin. Tunicamycin treatment, monitored by lectin-induced aggregation, drastically diminished cell adhesion to laminin and fibronectin, whereas cell binding to collagen IV was not affected. Arg-Gly-Asp (RGD)-related peptides were used to study the adhesion to collagen IV. The results show that a serine-containing RGD-related peptide GRGDSP has virtually no effect on colon carcinoma cell adhesion to type IV collagen. In contrast, when serine was substituted for threonine (GRGDTP) adhesion to collagen IV was strongly inhibited. After incubation of sialidase-treated cells with the threonine-containing peptide adhesion was almost totally blocked. These results demonstrate the existence of both RGD-dependent and carbohydrate-based mechanisms for metastatic human HT29 cell binding to collagen IV.
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PMID:Alterations in cell surface carbohydrate composition of a human colon carcinoma cell line affect adhesion to extracellular matrix components. 157 4

GM3-expressing cells adhere, spread and migrate on plastic plates coated with Gg3, LacCer and Gb4, but not with other glycosphingolipids (GSLs). Thus, cell adhesion, spreading and migration through GSL-GSL interaction occur in an analogous fashion to the interaction of cells with adhesive matrix proteins [AP, e.g. fibronectin (FN), laminin (LN)] through their integrin receptors. In this study, the adhesion of two GM3-expressing cell lines (B16 melanoma and HEL299 fibroblast) on plastic plates co-coated with GSL plus AP is compared with adhesion on plates coated with GSL (Gg3 or LacCer) alone, or coated with AP alone. Results show that: (i) cell adhesion on GSL-coated plates takes place earlier in the incubation period than that on AP-coated plates; (ii) cell adhesion, as well as spreading, was greatly enhanced (in terms of strength and rapidity) on plates co-coated with GSL plus AP; (iii) repulsion (negative adhesion) of cells was observed on plates co-coated with AP plus N-acetyl-GM3 (NAcGM3) and was presumably based on repulsive NAcGM3-NAcGM3 interaction; (iv) GM3-dependent cell adhesion on GSL-coated plates, as well as synergistic promotion of cell adhesion (based on the GSL-GSL and AP-integrin systems), was suppressed by incubation of cells with anti-GM3 monoclonal antibody DH2 or sialidase. Synergistic adhesion of cells on GSL/AP co-coated plates was less inhibited by incubation with peptide sequences RGDS or YIGSR than was adhesion on plates coated with AP alone.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Synergistic effect of two cell recognition systems: glycosphingolipid-glycosphingolipid interaction and integrin receptor interaction with pericellular matrix protein. 182 42

Fibronectins purified from human plasma (termed pFN), spent culture media of human fibroblasts WI38 (termed cFN), and SV40 virus-transformed WI38/VA13 cells (termed tFN) and their cleavage fragments were compared with respect to their binding activities to lectins and anti-carbohydrate antibodies reacting with chemically well-defined structures. The following findings were of particular interest. About 25-35% of cFN and tFN carried a binary sialosyl type 2 chain (NeuAc alpha 2----3/or 6Gal beta 1----4GlcNAc) linked beta 1----3/beta 1----6 to the galactose residue and defined by monoclonal antibody C6. This structure was not detected in pFN. In cFN, the C6-defined structure was localized within the gelatin-binding domain, whereas in tFN the same structure was absent from this domain but was located at the NH2-terminal region of the central domain. Other carbohydrate determinants, defined by Ricinus communis lectin and concanavalin A before and after sialidase treatment, showed essentially identical domain distribution patterns among cFN, tFN, and pFN and were all located at the gelatin-binding domain (44 kDa), its precursor (60 kDa), and the Cell/Hep-2 domain (155/145 kDa). Although both cFN and tFN were reactive with lentil lectin, pFN was not. Fibronectin from transformed cells (tFN) showed much greater reactivity than cFN and pFN with wheat germ lectin before sialidase treatment and showed enhanced reactivity with R. communis lectin and peanut lectin after sialidase treatment, indicating that tFN is more highly sialylated than cFN and pFN. All fibronectins examined were strongly reactive with monoclonal antibody AH8-28, which binds to Gal beta 1----3GalNAc residues, and this reactivity was localized to both the NH2-terminal half and COOH-terminal half of the S-cyanylation-cleaved fibronectin molecule.
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PMID:Domain-specific distribution of carbohydrates in human fibronectins and the transformation-dependent translocation of branched type 2 chain defined by monoclonal antibody C6. 242 70

The human multipotential hematopoietic cell line K562 expresses fibronectin receptor (FNR) subunits of 160 kDa (alpha chain) and 120 kDa (beta chain). Treatment with 12-O-tetradecanoylphorbol 13-acetate (TPA) led to reduced binding of K562 to immobilized fibronectin (FN), although treated cells expressed 10-fold more cell surface FNR than untreated cells. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis confirmed this and showed altered electrophoretic mobilities of FNR subunits from TPA-treated cells. TPA treatment affected N-linked glycosylation, as tunicamycin treatment of K562 cells abolished differences in FNR mobility. Sialidase treatment of FNR immunoprecipitates minimized and sialidase treatment of intact cells eliminated these mobility differences between subunits from control and TPA-treated cells. Reduced sialylation of FNR from TPA-treated cells was further demonstrated by chromatography with bead-coupled lectins and by the greater negative charge of untreated K562 FNR subunits in two-dimensional isoelectric focusing-polyacrylamide gel electrophoresis. A relationship between reduced FNR sialylation and reduced FN binding was suggested by adhesion assays of sialidase-treated K562 which showed that desialylation of cell surface FNR was associated with decreased cell adhesion. Thus, TPA treatment reduces the function, increases the expression, and alters the structure of K562 FNR, and these changes appear to involve FNR sialylation.
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PMID:Phorbol ester induces increased expression, altered glycosylation, and reduced adhesion of K562 erythroleukemia cell fibronectin receptors. 252 13

Fibronectins from human adult plasma, fetal plasma and from amniotic fluid obtained during early and late gestation were compared with respect to (i) their reactivity with lectins, (ii) their binding to the physiological ligands gelatin and heparin, and (iii) the role of the carbohydrate residues in the binding to these two ligands. The two fibronectin isoforms displayed distinct developmental differences in both glycosylation and binding properties: (i) Proportions of tri/tetraantennary complex glycans compared to the fraction of biantennary structures, as inferred from the reactivity with concanavalin A, were highest in amniotic fluid fibronectin from late pregnancy, lower in amniotic fluid fibronectin from early gestation, and even lower in fetal and adult plasma fibronectins. Likewise, fucose (alpha 1-6) linked to the innermost N-acetylglucosamine of the chitobiosyl core, defined by reactivity with Lens culinaris agglutinin (LCA), was present primarily in amniotic fluid fibronectin, and decreased in content during gestation from the 2nd. to the 3rd. trimenon. Both fetal and adult plasma fibronectins were only weakly reactive with LCA, indicating a low content of (alpha 1-6) linked fucose residues. After prior treatment with sialidase, both plasma and amniotic fluid fibronectins strongly reacted with erythrocyte phytohaemagglutinin (E-PHA), indicating that both fibronectin isoforms contain bisecting (beta 1-4) N-acetylglucosamine residues. Amniotic fluid fibronectins showed much greater reactivity than adult and fetal plasma fibronectins with wheat germ agglutinin; binding of this lectin to amnion fluid fibronectins was not decreased by desialylation indicating the presence of poly(N-acetyllactosamine) units. Whereas amniotic fluid fibronectins were strongly reactive with peanut agglutinin, neither adult nor fetal plasma fibronectins did bind to this lectin unless after prior desialylation. Hence, both fibronectin isoforms contain O-glycan residues that are fully sialylated in fetal and adult plasma fibronectins, but only partly sialylated in amniotic fluid fibronectins. According to these differences, glycosylation of plasma and amniotic fluid fibronectins is under developmental regulation. (ii) Amniotic fluid fibronectins had a significantly lower binding activity for both heparin and gelatin than plasma fibronectins. Moreover, amnion fibronectin from late gestation displayed a significantly lower binding to these two ligands than amnion fibronectin from early gestation. Fetal plasma fibronectins had a lower binding activity for gelatin than adult plasma fibronectin. (iii) Treatment of fibronectins with sialidase, fucosidase and removal of N-glycans with endoglycosidases H and F did not affect binding to gelatin and heparin, indicating that the interaction of plasma and amnion fibronectin with these two ligands is not influenced by their oligosaccharide moieties.
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PMID:Developmental changes in the glycosylation and binding properties of human fibronectins. Characterization of the glycan structures and ligand binding of human fibronectins from adult plasma, cord blood and amniotic fluid. 261 23

The asparagine-linked sugar chains of fibronectin purified from human placenta were quantitatively released as oligosaccharides by hydrazinolysis. After N-acetylation, they were converted to radioactive oligosaccharides by NaB3H4 reduction. The radioactive oligosaccharides were fractionated by their charge on an anion-exchange column chromatography. All of the acidic oligosaccharides could be converted to neutral oligosaccharides by sialidase digestion. These oligosaccharides were then fractionated by serial affinity chromatography using immobilized lectin columns. Study of each oligosaccharide by sequential exoglycosidase digestion and methylation analysis revealed the following information as to the structures of the sugar chains of human placental fibronectin: 1) nine sugar chains are included in one molecule; 2) all sialic acid residues are exclusively linked at the C-3 position of the galactose residues; 3) bi-, tri-, and tetraantennary complex-type oligosaccharides with the Man alpha 1----6(Man alpha 1----3)Man beta 1----4GlcNAc beta 1----4 (+/- Fuc alpha 1----6)-GlcNac as their cores were found; 4) the bisecting N-acetylglucosamine residue and the Gal beta 1----4GlcNAc beta 1----repeating groups are included in some of the sugar chains.
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PMID:Structures of asparagine-linked oligosaccharides of human placental fibronectin. 275 72

NCTC 2071A cells, a line of transformed murine fibroblasts, grow in serum-free medium, are deficient in gangliosides, synthesize fibronectin, but do not retain and organize it on the cell surface. When the cells are exposed to exogenous gangliosides, fibrillar strands of fibronectin become attached to the cell surface. A morphologically distinct variant of NCTC 2071A cells was observed to both retain cell surface fibronectin and organize it into a fibrillar network when the cells were stained with anti-fibronectin antibodies and a fluorescent second antibody. A revertant cell type appeared to resemble the parental NCTC 2071A cells in terms of morphology and fibronectin organization. All three cell types were subjected to mild NaIO4 oxidation and reduction with KB3H4 of very high specific radioactivity in order to label the sialic acid residues of surface gangliosides. The variant had much more surface gangliosides than the parental, particularly more complex gangliosides corresponding to GM1 and GD1a. The surface gangliosides of the revertant were intermediate between the parental and the variant. By using sialidase, which hydrolyzes GD1a to GM1, and 125I-labeled cholera toxin, which binds specifically to GM1, the identity and levels of these gangliosides were confirmed in the three cell types. When variant cells were exposed to sialidase for 2 d, there appeared to be little change in fibronectin organization. Concomitant treatment of the cells with the B subunit of cholera toxin, which bound to all the surface GM1 including that generated by the sialidase, however, eliminated the fibrillar network of fibronectin. In addition, exposure of the variant cells to a 70,000-mol-wt fragment of fibronectin, which lacks the cell attachment domain but contains a matrix assembly domain, inhibited the formation of fibers. Finally, all three cell types were assayed for their ability to attach to and spread on fibronectin-coated surfaces; no significant differences were found. Our results further establish that the ability of a cell to organize fibronectin into an extracellular matrix is dependent on certain gangliosides, but they also indicate that cell adhesion to fibronectin is independent of these gangliosides. We suggest that matrix organization and cell attachment and spreading are based on separate mechanisms and that these functions are associated with different cell surface "receptors."
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PMID:Fibrillar organization of fibronectin is expressed coordinately with cell surface gangliosides in a variant murine fibroblast. 370 Apr 77

Rat peritoneal macrophages bind and phagocytoze homologous sialidase-treated erythrocytes at a rate which is dependent on the amount of sialic acid that has been removed from the cells. Increased binding of erythrocytes is observed after the removal of 10-20% of membrane sialic acid, while for phagocytosis at least 30-40% of this substance must be removed. With Vibrio cholerae sialidase only a partial (80%) hydrolysis of rat erythrocyte sialic acid is possible, whereas Arthrobacter ureafaciens sialidase leads to complete desialylation and therefore causes stronger binding and phagocytosis of the erythrocytes than the V. cholerae enzyme. Preincubation of peritoneal macrophages with sialidase impairs binding and phagocytosis. Experiments were performed to account for the stimulation of binding and phagocytosis observed in the presence of native, homologous serum. However, an involvement of immunoglobulins and complement factors of the classical and alternative pathway in the engulfment process has been excluded. Fibronectin, tuftsin and substance P have no influence, either. On the other hand, peanut agglutinin and Erythrina crystagalli agglutinin are potent stimulators of binding and phagocytosis of sialidase-treated erythrocytes, whereas soybean agglutinin has only little and limulin no influence at all. It is concluded that sialidase-treated erythrocytes, having been bound to the beta-galactose-specific lectin on the macrophage surface, are phagocytozed as a function of their number and binding strength to the macrophages. The influence of native serum and especially of the plant lectins on this process is discussed.
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PMID:Binding and phagocytosis of sialidase-treated rat erythrocytes by a mechanism independent of opsonins. 664 29

The extent and the specificity of the initial cell attachment induced by various proteins coated on plastic surfaces have been studied with the following results: (a) Cell adhesion on the surfaces coated with sialidase and beta-galactosidase was as strong as on concanavalin A and limulus lectin-coated surfaces and the reactions were strongly inhibited by glycosidase inhibitors or by competitive substrates. The adhesion on sialidase was inhibited by 2-deoxy-2,3-dehydro-N-acetylneuraminic acid and by polysialoganglioside (GT1b) at low concentration (0.05-0.1 mM). The cell adhesion on beta-galactosidase coat was inhibited by 1,4-D-galactonolactone and beta-methylgalactoside but not by alpha-methylgalactoside. Thus, the initiation of cell adhesion on glycosidase surfaces could be mediated through the interactions of the specific binding sites of the enzyme surface with the cell surface substrates under physiological conditions. (b) Cell adhesion on various lectins could be blocked by various competing monosaccharides at the concentrations similar to the inhibitory concentrations for binding of lectins from solution to the cells. (c) Cell adhesion on fibronectin surfaces as well as on gelatin-coated surfaces was equally inhibited by GT1b at relatively high concentrations (0.25-0.5 mM). Lower concentrations of GT1b (0.05-0.1 mM) inhibited the cell adhesion on surfaces of Limulus lectin and sialidase. It is suggested that the cell adhesion mediated by fibronectin is based on yet unknown interactions in contrast to a specific cell adhesion through glycosidases and lectins.
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PMID:Studies on cell adhesion and recognition. I. Extent and specificity of cell adhesion triggered by carbohydrate-reactive proteins (glycosidases and lectins) and by fibronectin. 678 7


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