Homeostasis of Cell-surface Glycosphingolipid Content in B16 Melanoma Cells

Ito, Makoto; Komori, Hironobu

doi:10.1074/jbc.271.21.12655

Cited by 23 publications

(15 citation statements)

References 32 publications

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“…SM Restoration-The content of GM3 in B16 cells was reduced by endoglycoceramidase treatment but recovered quickly after the enzyme was removed from the culture medium (13). However, no restoration in SM content was observed after removal of SMase when B16 cells were prelabeled with [ 14 C]choline (Fig.…”

Section: Effects Of Smase On Glct-1 and Sm Synthase Activities Gsl Smentioning

confidence: 99%

“…Because the excess generation of ceramide must be toxic for the cell, the exclusion of ceramide from the cell by glycosylation can be regarded as a mechanism of defense against infection by SMase-producing pathogens. It is interesting to note that many opportunistic pathogens can also produce endoglycoceramidase extracellularly (13).…”

Section: Effects Of Smase On Glct-1 and Sm Synthase Activities Gsl Smentioning

confidence: 99%

“…Cells-We previously reported that endoglycoceramidase treatment of B16 melanoma cells stimulated GSL synthesis (13). Because ceramide is the common lipid backbone of GSLs and SM, we examined the metabolism of SM-derived ceramide using bacterial SMase instead of endoglycoceramidase.…”

Section: Effects Of Smase Treatment On Sphingolipid Metabolism In B16mentioning

confidence: 99%

“…We found that treatment of B16 melanoma cells with a microbial endoglycoceramidase activated GSL synthesis via transient up-regulation of UDP-glucose:ceramide glucosyltransferase-1 (GlcT-1, glucosylceramide synthase; EC2.4.1.80) (13). As a result, cell surface NeuAc␣2,3Gal␤1,4Glc␤1,1cer-amide (GM3), the end product of GSL synthesis in B16 cells, was restored quickly when the enzyme was removed from the culture medium (13).…”

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confidence: 99%

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Regulation of Intracellular Ceramide Content in B16 Melanoma Cells

Komori

Ichikawa

Hirabayashi

et al. 1999

Journal of Biological Chemistry

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We previously reported that ceramide released from glycosphingolipids (GSLs) by endoglycoceramidase was directly metabolized to GSLs, and thus the content of GSLs was constantly maintained in B16 melanoma cells (Ito, M., and Komori, H. (1996) J. Biol. Chem. 271, 12655-12660). In this study, the metabolism of ceramide released from sphingomyelin (SM) by bacterial sphingomyelinase (SMase) was examined using B16 cells and their GSL-deficient mutant counterpart GM95 cells. Treatment of B16 melanoma cells with bacterial SMase effectively hydrolyzed SM on the plasma membrane. Under these conditions, NeuAc␣2,3Gal␤1,4Glc␤1,1ceramide was significantly increased. Interestingly, UDP-glucose: ceramide glucosyltransferase-1 (GlcT-1) activity and GSL synthesis, but not SM synthesis or sphingosine generation, were found to be up-regulated by SMase treatment. The up-regulation of GSL synthesis seemed to occur at both the transcriptional and post-translational steps of GlcT-1 synthesis. Accumulation of ceramide by bacterial SMase was much higher in GM95 cells than in the parental cells. When the enzyme was removed from the culture medium, the intracellular ceramide level in B16 cells, but not that in the mutant cells, normalized. No rapid restoration of SM in either of the cell lines was observed after removal of the enzyme. SMase treatment strongly inhibited DNA synthesis in GM95 cells but not that in B16 cells. In the presence of D-threo-1-phenyl-2-decanoylamino-3-morpholino-1-propanol, an inhibitor of GlcT-1, SMase treatment markedly increased the ceramide content and thus inhibited DNA synthesis in B16 cells. Our study provides the first evidence that GlcT-1 functions to regulate the level of intracellular ceramide by glycosylation of the ceramide when it is present in excess.

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Section: Effects Of Smase On Glct-1 and Sm Synthase Activities Gsl Smentioning

confidence: 99%

Section: Effects Of Smase On Glct-1 and Sm Synthase Activities Gsl Smentioning

confidence: 99%

Section: Effects Of Smase Treatment On Sphingolipid Metabolism In B16mentioning

confidence: 99%

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confidence: 99%

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Regulation of Intracellular Ceramide Content in B16 Melanoma Cells

Komori

Ichikawa

Hirabayashi

et al. 1999

Journal of Biological Chemistry

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“…EGCase is an enzyme that specifically hydrolyzes the linkage between carbohydrates and ceramides in GSLs (36). With the aid of an activator protein, it is capable of releasing the carbohydrate moiety of GSLs on the cell surface without affecting other lipids and glycoproteins (37,38).…”

Section: Identification Of P135 As the Gpi-anchored Neuronal Cell Adhmentioning

confidence: 99%

Involvement of Gangliosides in Glycosylphosphatidylinositol-anchored Neuronal Cell Adhesion Molecule TAG-1 Signaling in Lipid Rafts

Kasahara¹,

Watanabe²,

Takeuchi³

et al. 2000

Journal of Biological Chemistry

144

129

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The association of ganglioside GD3 with TAG-1, a glycosylphosphatidylinositol-anchored neuronal cell adhesion molecule, was examined by coimmunoprecipitation experiments. Previously, we have shown that the anti-ganglioside GD3 antibody (R24) immunoprecipitated the Src family kinase Lyn from the rat cerebellum, and R24 treatment of primary cerebellar cultures induced Lyn activation and rapid tyrosine phosphorylation of an 80-kDa protein (p80). We now report that R24 coimmunoprecipitates a 135-kDa protein (p135) from primary cerebellar cultures. Treatment with phosphatidylinositol-specific phospholipase C revealed that p135 was glycosylphosphatidylinositol-anchored to the membrane. It was identified as TAG-1 by sequential immunoprecipitation with an anti-TAG-1 antibody. Antibody-mediated cross-linking of TAG-1 induced Lyn activation and rapid tyrosine phosphorylation of p80. Selective inhibitor for Src family kinases reduced the tyrosine phosphorylation of p80. Sucrose density gradient analysis revealed that the TAG-1 and tyrosine-phosphorylated p80 in cerebellar cultures were present in the lipid raft fraction. These data show that TAG-1 transduces signals via Lyn to p80 in the lipid rafts of the cerebellum. Furthermore, degradation of cell-surface glycosphingolipids by endoglycoceramidase induced an alteration of TAG-1 distribution on an OptiPrep gradient and reduced the TAG-1-mediated Lyn activation and tyrosine phosphorylation of p80. These observations suggest that glycosphingolipids are involved in TAG-1-mediated signaling in lipid rafts.Gangliosides, sialic acid-containing glycosphingolipids (GSLs), 1 are found in the outer leaflet of the plasma membrane of all vertebrate cells and are thought to play functional roles in cellular interactions and the control of cell proliferation (1-4).In the nervous system, where gangliosides are particularly abundant, the species and amounts of gangliosides undergo profound changes during development, suggesting that they may play fundamental roles in this process (5). The accumulation of gangliosides within the neurons in ganglioside storage diseases results in extensive neurite outgrowth (6). Exogenously administered gangliosides accelerate the regeneration of neurons in the central nervous system in vivo after lesioning (7). The addition of exogenous gangliosides to primary cultures of neurons and neuroblastoma cells in vitro stimulates cellular differentiation with concomitant neurite sprouting and extension (8 -10). Glucosylceramide synthesis, the first glycosylation step of GSL synthesis, is required for axonal growth in hippocampal neurons (11) and for embryonic development (12). Transfection of the ganglioside GD3 2 synthase cDNA into neuroblastoma cells induces their cholinergic differentiation and neurite sprouting (13). Finally, mice lacking complex gangliosides exhibit axonal degeneration (14). These data show that gangliosides are involved in neural cell differentiation and brain development. However, the molecular mechanisms underlying the ganglioside-depend...

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Scholarly use of internet‐based electronic resources

Zhang

2001

J. Am. Soc. Inf. Sci.

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This research examines the use of Internet‐based electronic resources (e‐sources) by a group of library and information science (LIS) scholars. It focuses particularly on how scholars use, cite, and evaluate e‐sources during the research process. This research also explores the problems scholars encounter and concerns they have when using e‐sources for research. The following approaches were used to collect data for the investigation: (a) a longitudinal analysis of e‐source citations in eight LIS journals from 1991 through 1998; (b) a survey of editors of the eight journals; and (c) a survey of 201 authors with articles to be published in the eight journals. The longitudinal analysis of e‐source citations shows that there has been a notable increase in the number and proportion of authors who cite e‐sources in their research articles over the 8‐year period, although at the time of this study, e‐sources were still cited much less frequently than print sources. This result provides empirical evidence that e‐sources are increasingly used among scholars. Complementing the citation data, the results from the author survey show that e‐sources are becoming an important component in scholars' research, and are serving a wide range of purposes and functions. The number of access points and self‐perceived overall ability to use the Internet are identified as the two significant variables affecting frequency of e‐source use. The results of this study also suggest that a limited number of criteria can be implemented in practice for scholars to evaluate electronic sources and systems. When citing e‐sources, scholars consider some factors that are unique to e‐sources, in addition to the factors they consider for print sources. Although the advantages of e‐sources promote citing, some drawbacks of e‐sources at this stage serve as a barrier. The survey of editors also reveals a lack of clearly stated editorial policies regarding citing e‐sources. The major problems and concerns reported by scholars regarding using e‐sources are summarized, and both the theoretical implications and practical applications of the findings are discussed.

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Homeostasis of Cell-surface Glycosphingolipid Content in B16 Melanoma Cells

Cited by 23 publications

References 32 publications

Regulation of Intracellular Ceramide Content in B16 Melanoma Cells

Regulation of Intracellular Ceramide Content in B16 Melanoma Cells

Involvement of Gangliosides in Glycosylphosphatidylinositol-anchored Neuronal Cell Adhesion Molecule TAG-1 Signaling in Lipid Rafts

Scholarly use of internet‐based electronic resources

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