Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027819 (neuroblastoma)
 27,800 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Removal of sialic acid from intact mammalian nervous system cells in tissue culture is accompanied by an immediate increase in cellular cholinesterase activity. Treatment of hamster astroblast cells (clonal line NN) and mouse neuroblastoma cells (clonal lines S21, N18, and N115) for brief periods with a low level of Clostridium perfringens sialidase, 5 X 10(-3) units/ml, removed 1-15 mug of sialic acid per mg of cell protein and brought about a large increase in v0 and Vmax of cellular acetylcholinesterase (EC 3.1.1.7). Butyrylcholinesterase (EC 3.1.1.8) activities also increased upon careful enzymatic removal of cellular sialic acid, and cells with characteristically low butyrylcholinesterase activity, e.g., adrenergic clonal line N115 neuroblasts displayed relatively high activity after treatment with sialidase. These findings open the possibility that adaptive regulation of cholinesterases in mammalian cells may be mediated rapidly through changes in their sialic acid content.
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PMID:Activation of acetyl- and butyrylcholinesterase by enzymatic removal of sialic acid from intact neuroblastoma and astroblastoma cells in culture. 17 21

Several lines of evidence suggest that gangliosides may play a role in the regulation of growth in many cell types. Here we describe the effects on growth of two different cell lines by the addition of two different chemicals which have been reported to elevate the cellular ganglioside content through different mechanisms. Growth of neuroblastoma (Neuro 2a) cells in medium containing fetal bovine serum was inhibited in a dose-dependent fashion by both exogenous GM1 ganglioside and NeuAc2en, an inhibitor of sialidase activity. In contrast, growth of glioma cells (U-1242 MG) was not affected by exogenous GM1 or NeuAc2en in the presence of as little as 1% calf serum. However, NeuAc2en inhibited growth of U-1242 MG cells stimulated by platelet-derived growth factor in serum-free medium. These results demonstrate that the growth inhibitory effects of ganglioside on U-1242 MG but not Neuro 2a cells can be counteracted by serum, suggesting that the mechanisms through which gangliosides affect cell growth may be different for different growth factors and cell types.
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PMID:Effects of GM1 and 2-deoxy-2,3-dehydro-N-acetylneuraminic acid (NeuAc2en) on neuroblastoma (Neuro 2a) and human glioma cells (U1242 MG). 182 41

Density-dependent changes in ganglioside composition, Vibrio cholerae neuraminidase (VCN)-susceptible sialyl residues, and membrane-associated sialidase activity were determined for the cholinergic murine neuroblastoma cell line S20Y. A decrease in total ganglioside sialic acid and VCN-releasable sialic acid was observed with increasing cell density. GM3 was the major ganglioside component of preconfluent S20Y cells, whereas GD1a was predominant in postconfluent cells. Sialidase activity increased in confluent and postconfluent cells and may account for the reduction in total ganglioside sialic acid observed with increasing cell density. In contrast, while adrenergic N115 cells showed a decrease in VCN-susceptible sialic acid residues with increasing cell density, there was no significant change in ganglioside composition or ganglioside sialic acid levels.
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PMID:Density-dependent changes in gangliosides and sialidase activity of murine neuroblastoma cells. 711 93

In cultured human neuroblastoma cells (SK-N-MC), a plasma membrane-bound besides a lysosomal ganglioside GM3 sialidase was detected. Both activities can be distinguished by the specific activation with detergents, as well as differential inhibition by Cu++. Plasma membrane and lysosomal sialidase specific activities showed strikingly different behaviour during the growth phase of neuroblastoma cells. Thus, the plasma membrane sialidase increased about 15-fold and mirrored cell growth, it differed from the kinetics of ornithine decarboxylase, an early marker of cell proliferation. The lysosomal sialidase, on the other hand, exhibited constant specific activities during growth of the cells, as did lysosomal and plasma membrane marker enzymes. When the sialidase inhibitor 2,3-dehydro-2-deoxy-N-acetylneuraminic acid was included in the culture medium, a profound change in proliferation kinetics was observed, indicating a release from density-dependent control of cell division. Additionally, the inhibitor abolished the increase of the biochemical differentiation marker acetylcholinesterase. The results suggest an important role of the ganglioside sialidase of the plasma membrane in the processes of proliferation control and differentiation in this neuronal cell system.
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PMID:Role of plasma membrane ganglioside sialidase of human neuroblastoma cells in growth control and differentiation. 814 59

Gangliosides of the plasma membrane are important modulators of cellular functions. Previous work from our laboratory had suggested that a plasma membrane sialidase was involved in growth control and differentiation in cultured human neuroblastoma cells (SK-N-MC), but its substrates had remained obscure. We now performed sialidase specificity studies in subcellular fractions and found ganglioside GM3 desialylating activity in presence of Triton X-100 to be associated with the plasma membrane, but absent in lysosomes. This Triton-activated plasma membrane enzyme desialylated also gangliosides GD1a, GD1b, and GT1b, thereby forming GM1; cleavage of GM1 and GM2, however, was not observed. Sialidase activity towards the glycoprotein fetuin with modified C-7 sialic acids and towards 4-methylumbelliferyl neuraminate was solely found in lysosomal, but not in plasma membrane fractions. The role of the plasma membrane sialidase in gangliosides desialylation of living cells was examined by following the fate of [3H]galactose-labelled individual gangliosides in pulse-chase experiments in absence and presence of the extracellular sialidase inhibitor 2-deoxy-2,3-dehydro-N-acetylneuraminic acid. When the plasma membrane sialidase was inhibited, radioactivity of all gangliosides chased at the same rate. In the absence of inhibitor, GM3, GD1a, GD1b, GD2, GD3 and GT1b were degraded at a considerably faster rate in confluent cultures, whereas the GM1-pool seemed to be filled by the desialylation of higher gangliosides. The results thus suggest that the plasma membrane sialidase causes selective ganglioside desialylation, and that such surface glycolipid modification triggers growth control and differentiation in human neuroblastoma cells.
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PMID:Selective ganglioside desialylation in the plasma membrane of human neuroblastoma cells. 872 44

This paper describes the preparation of monosialoganglioside GM1 with sialidase-producing marine bacteria as a microbial biocatalyst. A new sialidase-producing bacterium, identified tentatively as Pseudomonas sp. strain YF-2, was isolated from seawater by enrichment culture with ganglioside as the sole source of carbon. When YF-2 was cultured in a synthetic medium containing crude bovine brain gangliosides at 25 degrees C for 3 days, 80 to 90% of the gangliosides were converted to GM1. GM1 was then purified from the supernatant of YF-2 culture by C18 reverse-phased chromatography, followed by DEAE-Sephadex A25 anion-exchange chromatography. In a typical experiment, 178 mg of highly purified GM1 was obtained from 500 mg of the crude ganglioside fraction. The GM1 induced neurite outgrowth of neuroblastoma Neuro2a cells at a concentration of 33 to 100 microM in the presence of fetal calf serum. Sialidase was purified 33-fold with 13.3% recovery from the culture supernatant of YF-2. The purified enzyme hydrolyzed polysialogangliosides to produce GM1 but did not act on GM1. It was therefore concluded that polysialogangliosides in the culture of strain YF-2 were converted to GM1 by this sialidase.
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PMID:Preparation of GM1 ganglioside with sialidase-producing marine bacteria as a microbial biocatalyst. 914 18

Gangliosides on the external side of the plasma membrane are important modulators of cellular functions. In previous work we had found that in cultured human SK-N-MC neuroblastoma cells a cell surface sialidase activity specifically cleaved terminal sialic acids from gangliosides, leading to a shift from higher sialylated species to GM1 and a decrease of GM3. To further elucidate the function of the enzyme, we have now examined the consequences of ganglioside sialidase inhibition. When present in the culture medium, the ganglioside sialidase inhibitors 2-deoxy-2,3-dehydro-N-acetylneuraminic acid (NeuAc2en), heparin, and heparan sulfate caused dramatic changes in cell behavior. Thus, the inhibitors uniformly led to a complete release from contact inhibition of growth, and to the loss of the differentiation markers neuron-specific enolase and neurofilaments, and a decrease of cyclic AMP. In presence of NeuAc2en, cells that normally were spread out evenly and were firmly attached, appeared smaller, rounded, and only loosely adherent to the culture vessel. Exogenous addition of vibrio cholerae sialidase mimicked the action of the plasma membrane ganglioside sialidase by retarding cell proliferation and increasing intracellular acetylcholinesterase. That the ganglioside sialidase inhibitors in the culture medium indeed affected solely the cell surface enzyme and not also a lysosomal sialidase, was demonstrated in an experiment where the desialylation of exogenously added radioactive gangliosides was determined in absence and presence of NeuAc2en and NH4Cl, an inhibitor of lysosomal function. Taken together, our results suggest that the ganglioside sialidase on the surface of SK-N-MC cells is responsible for growth control and differentiation in this neuronal cell line.
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PMID:Effects of cell surface ganglioside sialidase inhibition on growth control and differentiation of human neuroblastoma cells. 917 66

Gangliosides, constituents of surfaces of vertebrate cells, modulate important cellular functions. Ganglioside-specific sialidases that possibly control these processes have been observed in a number of tissues, but their characterization has proved difficult due to their low abundance and lability. Here we describe the partial isolation and characterization of a ganglioside sialidase from human brain grey matter. After membrane extraction with octylglucoside, the enzyme was purified about 1300-fold by ion-exchange, affinity and gel-permeation chromatographies. Although PAGE still showed several protein bands, specific photoaffinity labelling with iodinated 5-N-acetyl-9-(4-azidosalicoylamido)-2,9-dideoxy-2,3-didehydrone uraminic acid identified a single polypeptide of 60 kDa likely to contain the active site of the sialidase. In the presence of 0.4% octylglucoside, the purified sialidase desialylated gangliosides G(M3), G(D1a), G(D1b) and G(T1b), but was inactive towards G(M1), G(M2), colominic acid, sialyl-(alpha2-3)-lactose, 2-(4-methylumbelliferyl)-neuraminate, or the glycoprotein fetuin. The ganglioside sialidase activity was strongly inhibited by 2-deoxy-2,3-didehydro-N-acetylneuraminic acid, heparin and heparan sulfate. Because of its substrate and inhibitor profiles, the purified enzyme resembles the activity characterized previously in the plasma membrane of human neuroblastoma cells, but is distinct from a lysosomal activity. The purified brain sialidase thus appears to function in the selective desialylation of gangliosides with terminal sialic acid residues.
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PMID:Partial characterization and enrichment of a membrane-bound sialidase specific for gangliosides from human brain tissue. 934 12

We previously cloned cDNAs encoding two different polysialic acid (PSA) synthases, ST8Sia II and IV, from mouse, and showed that both mouse ST8Sia II and IV can synthesize PSA on the neural cell adhesion molecule (NCAM) as well as other glycoproteins such as fetuin, at least in vitro (Kojima, N., Tachida, Y., Yoshida, Y., and Tsuji, S. (1996) J. Biol. Chem. 271, 19457-19463]. In the present study, to clarify how the two PSA synthases act differently in vivo, we first cloned PSA-expressing cell lines (N2a-II and N2a-IV) by stable transfection of the cDNA encoding either mST8Sia II or IV into mouse neuroblastoma Neuro2a cells, which do not express PSA but express NCAM, then compared the expression of the PSA and NCAM isoforms and de novo synthesis of PSA between N2a-II and N2a-IV. Western blotting with an anti-NCAM polyclonal antibody showed that NCAM was expressed as the polysialylated form in both ST8Sia II cDNA-transfected and ST8Sia IV cDNA-transfected Neuro2a cells, but that the polysialylated NCAMs expressed in ST8Sia IV cDNA-transfected clones migrated much slower on SDS-PAGE than those expressed in ST8Sia II cDNA-transfected clones. The slower migration of polysialylated NCAM of the ST8Sia IV cDNA-transfected clone (N2a-IV) than that of the ST8Sia II cDNA-transfected clone (N2a-II) was also observed when cells were metabolically labeled with [3H]glucosamine or pulse-chase labeled with [35S] methionine followed by immunoprecipitation with anti-PSA antibody or anti-NCAM monoclonal antibody. In addition, polysialylated N-glycans of PSA-carrying glycoproteins prepared from [3H] glucosamine-labeled N2a-IV by immunoprecipitation with anti-PSA monoclonal antibody were eluted at a much higher salt concentration than those from [3H] glucosamine-labeled N2a-II on an anion-exchange column. These results indicated that the degree of de novo polysialylation of NCAM by mST8Sia IV was much higher than that by mST8Sia II. In N2a-IV, NCAM-120, -140, and -180 were expressed as polysialylated forms, while polysialylation was restricted to NCAM-140 and -180, i.e., not NCAM-120, in N2a-ST8Sia II. Metabolic labeling of the cells with [3H] glucosamine, pulse-chase labeling with [35S] methionine followed by immunoprecipitation with anti-PSA antibody, and subsequent sialidase treatment revealed that NCAM-140 and -180 were specifically polysialylated in N2a-II, whereas not only NCAM but also other glycoproteins were de novo polysialylated in N2a-IV. The above results demonstrated that the two different PSA synthases, mST8Sia II and IV, synthesize PSA of different lengths on different substrate glycoproteins in vivo when the enzymes are expressed in neuroblastoma Neuro2a cells. These differences suggest that mST8Sia II and IV play different roles in the biosynthesis and expression of PSA.
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PMID:Two polysialic acid synthases, mouse ST8Sia II and IV, synthesize different degrees of polysialic acids on different substrate glycoproteins in mouse neuroblastoma Neuro2a cells. 949 75

Cell density-dependent inhibition of growth and neural differentiation in the human neuroblastoma cell line SK-N-MC are associated with a ganglioside sialidase-mediated increase of GM1 and lactosylceramide at the cell surface. Because these glycolipids expose galactose residues, we have initiated the study of the potential role of galectins in such cellular events. Using specific antibodies, galectin-1 but not galectin-3 was found to be present at the cell surface. Assessment of carbohydrate-dependent binding revealed a saturable amount of ligand sites approaching 2.6 x 10(6) galectin-1 molecules bound/cell. Presence during cell culture of the sialidase inhibitor 2-deoxy-2,3-dehydro-N-acetylneuraminic acid or of the GM1-binding cholera toxin B subunit effected a decrease of the presentation of galectin-1 ligands by 30-50%. The assumption that GM1 is a major ligand for galectin-1 was reinforced by the correlation between the number of carbohydrate-dependent 125I-iodinated GM1-neoganglioprotein binding sites and the amount of immunoreactive surface galectin-1, the marked sensitivity of probe binding to the presence of anti-galectin-1 antibody, and the inhibition of cell adhesion to surface-immobilized GM1 by the antibody. The results open the possibility that the carbohydrate-dependent interaction between ganglioside GM1 and galectin-1 may relay sialidase-dependent alterations in this cell system.
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PMID:Galectin-1 is a major receptor for ganglioside GM1, a product of the growth-controlling activity of a cell surface ganglioside sialidase, on human neuroblastoma cells in culture. 955 10


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