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

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Query: EC:3.1.1.53 (sialidase)
2,694 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The entry of blood-borne lymphocytes into most secondary lymphoid organs is initiated by a highly specific adhesive interaction with the specialized cuboidal endothelial cells of high endothelial venules (HEV). The adhesive receptors on lymphocytes that dictate interactions with HEV in different lymphoid organs are called homing receptors, signifying their critical role in controlling organ-selective lymphocyte migration. Considerable work has established that the mouse peripheral lymph node homing receptor (pnHR), defined by the mAb MEL-14, functions as a lectin-like adhesive protein. We have previously shown that sialidase treatment of peripheral lymph node (PN) HEV abrogates lymphocyte attachment to the HEV both in vivo and in vitro. We extend this evidence by demonstrating that Limax agglutinin (LA), a sialic acid-specific lectin, when reacted with HEV exposed in cryostat-cut tissue sections, blocks lymphocyte attachment to PN HEV and, unexpectedly, to the HEV of Peyer's patches (PP) as well. Using a recombinant form of the pnHR as a histochemical probe for its cognate adhesive site (HEV-ligand) on PN HEV, we demonstrate that both sialidase and Limax agglutinin functionally inactive this ligand. It is concluded that the requirement for sialic acid is at the level of the pnHR interaction with its HEV ligand. A distinct sialyloligosaccharide may encode the recognition determinant of a PP HEV ligand.
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PMID:Requirement for sialic acid on the endothelial ligand of a lymphocyte homing receptor. 227 86

Two autologous human melanoma cell lines were studied to determine their capacities to bind wheat germ agglutinin (WGA). Both cell lines were derived from the same patient, the first, IGR 39, originated from the primary tumor, the second, IGR 37, was established from a metastatic lymph node. WGA binding sites on the surface of these cell lines were compared before and after sialidase and/or tunicamycin treatments. IGR 39 cells exhibited two classes of WGA binding sites with high and low affinities, whereas IGR 37 cells had only one class of high affinity binding sites. After tunicamycin treatment, the capacity of IGR 39 cells to bind WGA was markedly altered, since only one class of WGA binding sites with high affinity was observed under these conditions, whereas tunicamycin did not induce significant changes in the lectin binding of IGR 37 cells. The low affinity WGA binding sites, which were only found on IGR 39 cells, corresponded to sialyl residues present in N-linked glycoproteins. The high affinity binding sites present on both cell lines probably involved sialyl and N-acetyl-glucosaminyl residues associated with O-linked glycoproteins and/or glycolipids. No direct correlation could be drawn between the number of WGA binding sites and the overall sialic acid levels exposed to sialidase treatment. The 3-fold increase in the amount of cell surface glycopeptides obtained after pronase digestion and specifically binding to WGA-Sepharose was in good agreement with the overall higher number of WGA binding sites on IGR 39 compared to IGR 37 cells. Thus, subtle carbohydrate changes of cell surface glycoconjugates might account for the differences between the biological properties of human melanoma cell lines of low and high tumorigenicity.
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PMID:WGA binding to the surface of two autologous human melanoma cell lines: different expression of sialyl and N-acetylglucosaminyl residues. 234 28

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

Histamine release from human basophils was investigated in vitro after removal of cell membrane sialic acid by three different sialidases. Pretreatment of the cells with sialidases from Cl. Perfringens, V. Cholera or Influenza virus A2 enhanced histamine release induced by subsequent stimulation of the cells with anti-IgE or the plant lectin Concanavalin A and caused a shift to the left of the dose-response curve for anti-IgE. The enhanced histamine release was reflected in a increased calcium sensitivity, thus suggesting that cell membrane sialic acid might be involved in the calcium fluxes preceeding histamine release. In higher doses the sialidase from Cl. Perfringens caused the cells to release histamine by itself, whereas the sialidases from V. Cholera and Influenza virus A2 in high doses inhibited the cell response to Concanavalin A.
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PMID:Enhancement of histamine release from human basophils pretreated with different sialidases. 242 28

The carbohydrate dependence of epitopes in the herpes simplex virus type 1-specified glycoprotein C (gC) was studied using a new solid-phase assay procedure. Glycoprotein C, coated on 96-well microtitre plates, was treated with sialidase and increasing concentrations of periodate. A sequential removal of peripheral monosaccharides from the oligosaccharides of gC was ascertained by an enzyme-linked lectin assay. By using a panel of gC-specific monoclonal antibodies in ELISA, it was found that gC contained two types of epitopes differing in their dependence on terminal galactose and sialic acid for expression. Control experiments indicated that the carbohydrate-dependent epitopes were peptide structures and that the carbohydrates did not directly participate in the antibody-binding reaction. The carbohydrate-dependent epitopes were mapped to antigenic site II, according to the proposed nomenclature, whereas those expressed also in the absence of peripheral sugars were located mainly in antigenic site I. These results were compatible with the relative distribution of oligosaccharides in the gC molecule.
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PMID:Demonstration and mapping of highly carbohydrate-dependent epitopes in the herpes simplex virus type 1-specified glycoprotein C. 243 9

Structures of oligosaccharides in submandibular glycoproteins were evaluated in situ. Sections of fixed paraffin-embedded glands from rats, mice, hamsters, sheep, and man were stained with a battery of lectins conjugated to horseradish peroxidase in conjunction with other methods, such as digestion with sialidase with or without prior saponification and/or periodate oxidation. Secretory glycoproteins showed a characteristic lectin binding pattern for each genus. Sialoglycoconjugates were detected in acinar cell secretions in all genera except the rat but differed with respect to the linkage of sialic acid to penultimate beta-galactose or alpha-N-acetylgalactosamine. Species and strains of mice showed minor differences in the structure of secretory glycoproteins. Sexes differed similarly in some but not other mouse species. Individual differences were seen in human glands, where oligosaccharide structure varied in relation to ABO blood group. In some species, heterogeneity in glycoprotein structure was observed among morphologically similar cells within a gland. Differences in the structure of salivary secretions between genera and between humans of different ABO blood type and secretor status substantiate biochemical and histochemical findings. The results showing species, sex, and individual differences in mice and heterogeneity in acinar cells in several species suggest a greater degree of genetic and perhaps hormonal influence on the synthesis of salivary glycoproteins than has previously been recognized.
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PMID:Genetic and sex-related differences in the structure of submandibular glycoconjugates. 244 18

Wilms' tumor has been proposed to originate from a developmental abnormality of the metanephric blastema. This undifferentiated component of Wilms' tumors has previously eluded efforts for in vitro growth. Blastema from a "classical" Wilms' tumor was transplanted into nude mice and passaged through 12 generations of heterotransplantation. Tumors from heterotransplants were grown for 12 serial passages in a serum-free growth medium supplemented with hormones and conditioned media from human kidney proximal tubule cells. The blastema initially grew on a collagen-fetal calf serum matrix as multicellular spheroids, and the cells proliferating from the rim of the spheroids had a flattened shape. Pulse-labeling with bromodeoxyuridine (BrdU) identified the proliferating cell population as blastemal in origin. Except for a loss of extracellular matrix, ultrastructural studies demonstrated morphologic similarities in the cultured cells, compared with the primary tumor and heterotransplants. Lectin histochemical stains for the peanut lectin (PNA) and immunohistochemical stains for cytokeratin (CYTO), vimentin (VIM), and epithelial membrane antigen (EMA) were performed on the original tumor, successive heterotransplants, and cells grown in vitro. The PNA stained the surface of the blastemal cells after sialidase digestion in the original tumor, heterotransplants, and cultured cells. The blastema of the original tumors was negative for CYTO and EMA but reactive for vimentin. This lack of differentiation was maintained in heterotransplants through 12 passages. However, blastemal cells demonstrated coexpression of CYTO and VIM intermediate filaments when grown in a serum-free medium on a matrix material. These studies demonstrate that the blastemal component of Wilms' tumor can be successfully grown in culture, passaged in nude mouse heterotransplants, and shown to undergo early stages of blastemal differentiation in vitro by growth in serum-free medium. This in vitro system provides a model for testing the factors that influence the growth and differentiation of the blastemal component of Wilms' tumors.
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PMID:The in vitro growth, heterotransplantation, and immunohistochemical characterization of the blastemal component of Wilms' tumor. 244 11

By selection for plastic adhesiveness we have previously established a variant tumor line (ESb-MP) from the metastatic murine lymphoma ESb. In contrast to the parental line, the adhesion variant is significantly decreased in malignancy and is altered in the capacity to bind soybean agglutinin (SBA) lectin. Here we show biochemically that the major SBA-binding cell-surface component of ESb-MP cells is the T200 glycoprotein. In ESb cells, T200 antigens bind SBA only after sialidase treatment. Enzymatic studies suggested that glycans detected by the lectin with or without sialidase treatment are different. Inhibition of N-glycosylation by tunicamycin and biosynthetic labeling revealed two T200 chains for ESb-MP cells that were larger in size than the single chain detected in ESb cells. Studies on the biosynthesis revealed that ESb-MP cells expressed two precursor chains for T200 whereas ESb cells displayed only one. There was no size difference detectable in the mature T200 molecules of ESb and ESb-MP cells. Our data suggest that the molecules differ in expression of O-linked glycans that can be recognized by SBA. Additional O-linked sugars on ESb-MP T200 molecules seem to be expressed in particular after trimming of the second T200 precursor chain.
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PMID:Structural basis for altered soybean agglutinin lectin binding between a murine metastatic lymphoma and an adhesive low malignant variant. 244 94

An antibody-lectin enzyme immunoassay (EIA) technique was developed for the analysis of sugar chains of serum alpha-fetoprotein in various liver diseases. The anti-'alpha-fetoprotein'-IgG was coated on a microtiter plate and then treated with periodic acid. A serum sample was added to the plate and then a 'peroxidase'-conjugated lectin was added. The amount of lectin bound to the sugar chain of the 'alpha-fetoprotein' was estimated from the 'peroxidase' activity. The 'peroxidase' activities of 4 different lectins, LCA, Con A, LCA and EPHA, were compared. The LCA/'wheat germ agglutinin' activity ratio and LCA/EPHA activity ratio were increased in liver diseases and LCA/'wheat germ agglutinin' ratio showed a statistically significant difference between the chronic hepatitis and the liver cirrhosis groups (p less than 0.05). Furthermore, when serum samples were pretreated with sialidase, a statistically significant difference was observed in the LCA/EPHA and LCA/Con A ratios between the chronic hepatitis and the hepatoma groups (p less than 0.05). These results indicated that low sialylation at the non-reduced end of the sugar chains of 'alpha-fetoprotein' occurs in liver cirrhosis and that high fucosylation at the reduced end of N-acetylglucosamine residue of 'alpha-fetoprotein' occurs in hepatomas.
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PMID:Alpha-fetoprotein antibody-lectin enzyme immunoassay to characterize sugar chains for the study of liver diseases. 246 50

Histochemical analyses of the chemical structures of sugar sequences with or without blood group specificity were carried out by combined stepwise digestion of tissue sections with exo- and endoglycosidases and subsequent lectin stainings in formalin-fixed, paraffin-embedded human pancreas. In acinar cells from blood group A or AB secretor individuals, sequential digestion with alpha-N-acetylgalactosaminidase and alpha-L-fucosidase imparted reactivity with peanut agglutinin (PNA) in cells reactive with Dolichos biflorus agglutinin as well as those with Ulex europaeus agglutinin I(UEA-I). Simple fucosidase digestion imparted the PNA reactivity only in UEA-I reactive cells. Sequential digestion with alpha-galactosidase and fucosidase likewise liberated the PNA binding sites in Griffonia simplicifolia agglutinin I-B4 reactive cells from blood group B and AB secretors. Sialidase digestion liberated the PNA binding sites not only in acinar cells but also intercalated duct cells, islet cells of Langerhans and endothelial cells. The PNA reactivity obtained by these enzyme digestions was eliminted by endo-alpha-N-acetylgalactosaminidase (endo-GalNAcdase) digestion. Preexisting PNA affinity in acinar cells from non-secretors was also susceptible to endo-GalNAcdase treatment. Following the endo-GalNAcdase digestion, fucosidase or sialidase digestion recovered the PNA reactivity in acinar cells from nonsecretors. These results show that ABH determinants carried on O-glycosidically linked type 3 chain (D-galactose-(beta 1-3)-N-acetyl-D-galactosamine alpha 1-serine or threonine) are secreted in pancreatic acinar cells and suggest that product coded by the secretor gene is required for the complete conversion of type 3 precursor chains into H determinants.
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PMID:Histochemical demonstration of O-glycosidically linked, type 3 based ABH antigens in human pancreas using lectin staining and glycosidase digestion procedures. 247 5


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