Astrocytes in cell culture incorporate GM1 ganglioside

Mascó, Daniel H.; Flott, Berenike E.; Seifert, W.

doi:10.1002/glia.440020404

Cited by 15 publications

(14 citation statements)

References 34 publications

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“…In the cultured chick astrocytes, we could not detect any significant direct incorporation of nervonic acid into gangliosides, which were mainly GM3, GM2, GD3, and GDla. The presence of and the ability to synthesize gangliotetraose species in cultured astrocytes have been controversial problems (Asou and Brunngraber, 1983;Sbashnig-Agler et al, 1988;Masco et al, 1989). However, we detected GM2 and GDla in the cultured astrocytes;, and these gangliosides were efficiently labeled by [3H]galactose in the medium (authors' unpublished1 data).…”

Section: Discussionmentioning

confidence: 75%

Incorporation of Very‐Long‐Chain Fatty Acids into Sphingolipids of Cultured Neural Cells

Shimada

1991

Journal of Neurochemistry

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We examined effects of exogenous very-long-chain fatty acids on lipids of cultured chick neurons and astrocytes. When chick neurons were incubated in chemically defined medium containing 10 microM nervonic acid (C24:1) for 7 days, it was found that a major fatty acid moiety of gangliosides and sphingomyelin was nervonic acid itself, which was not normally detected in the sphingolipid fraction. This alteration in the fatty acid composition apparently occurred in each ganglioside species. Under these experimental conditions, nervonic acid was not found in the glycerophospholipid fraction, and the amounts of triacylglycerol and free nervonic acid increased. Addition of behenic acid (C22:0) or erucic acid (C22:1) also induced changes in the fatty acid composition of gangliosides. When chick astrocytes were incubated in the presence of 10 microM nervonic acid for 7 days, no significant change was observed in the fatty acid composition of gangliosides. These studies indicate that the manipulation of the fatty acid moiety of sphingolipids in cultured neurons is possible.

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Section: Discussionmentioning

confidence: 75%

Incorporation of Very‐Long‐Chain Fatty Acids into Sphingolipids of Cultured Neural Cells

Shimada

1991

Journal of Neurochemistry

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“…1980; Masco et al, 1989) and that following such insertion it can act as a functional receptor for CT (Fishman, 1982;Spiegel, 1988) lend support to the contention that in the nervous system the effects of exogenous ganglioside GM 1 may reflect the function of its endogenous counterpart. The examination of the role of endogenous gangliosides in modulating neuritogenesis presents a more difficult task due to the lack of specific probes.…”

Section: Discussionmentioning

confidence: 83%

Interaction of ganglioside GM1 with the B subunit of cholera toxin modulates growth and differentiation of neuroblastoma N18 cells

1991

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The present study uses the B subunit of cholera toxin, a protein that binds specifically to ganglioside GM1, to examine the role of endogenous GM1 in the process of growth and differentiation of mouse neuroblastoma N18 cells. Binding of the B subunit to neuroblastoma N18 cells inhibited DNA synthesis with concomitant induction of differentiation. The B subunit induced pronounced morphological changes: an increase in neurite outgrowth with branched neurites and spinelike processes. The distinct morphological alterations and neuritogenesis in response to the B subunit were also revealed by immunofluorescence with fluorescein-labeled B subunit. The mechanism of the B subunit-induced differentiation is different than that of spontaneous differentiation. Thrombin, a serine protease present in normal serum, inhibits neurite outgrowth induced by the removal of serum from the medium. In contrast, thrombin did not cause retraction of the neurites induced by the B subunit. Thus, thrombin or a thrombin- like protease is not involved in the process of neurite outgrowth mediated through endogenous GM1. The biological effects of the B subunit are due to the binding of the B subunit to ganglioside GM1 and not due to changes in cAMP levels resulting from contaminating A subunit. We used highly purified cloned B subunit that cannot contain any A subunit because it was isolated from a Vibrio cholerae mutant that only expresses the B subunit. Neither the cloned nor commercial preparations of the B subunit induced increases of cAMP in these cells. There was a good correlation between the amount of B subunit bound to the cells and the biological effect. Finally, treatment with neuraminidase, which caused a fourfold increase in the level of membrane GM1 as determined by iodinated cholera toxin binding, enhanced the biological effect of the B subunit. However, neuraminidase treatment alone did not have significant effects, either on DNA synthesis or on morphology of the cells, indicating that elevations in the level of GM1 per se are not sufficient by themselves to cause significant changes in cell growth or differentiation. It seems most likely that the aggregation of endogenous GM1 on the cell surface by the B subunit is responsible for these effects on mouse neuroblastoma N18 cells.

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“…Different glutamate uptake systems have been described. In addition to the well-known Na+-dependent uptake (Bennett et al, 1973; Henn et al, 1974; Kimelberg et al, 1989; Schousboe et al, 1977) and the more recently described C1--dependent transport mechanism (Pin et al, 1984; Zaczek et al, 1987), a third uptake system that is active in the absence of both Na+ and C1and that is stimulated by Ca++ ions has been described in our laboratory (Hollmann et al, 1988; Hollmann and Seifert, 1989). These investigations have been performed in synaptic plasma membrane preparations.…”

Section: Introductionmentioning

confidence: 80%

Characterization of glutamate uptake systems in astrocyte primary cultures from rat brain

Flott

Seifert

1991

Glia

Self Cite

111

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The dependence of 3[H]-L-glutamate uptake on the presence of sodium, chloride, or calcium ions or on a combination of the three was investigated in astrocyte primary cultures. A stimulating effect on glutamate uptake by each of the ions tested was found. In addition to the comparably small effect by calcium alone, calcium exhibits a synergistic effect on the sodium- and chloride-dependent uptake. The sodium-dependent transport accumulates the glutamate analogue D-aspartate as well as L-glutamate. L-aspartate is taken up by about 50% of the values observed for L-glutamate transport. Sodium-dependent glutamate uptake is strongly inhibited by aspartate-beta-hydroxamate (A beta H) and threo-beta-hydroxyaspartate (T beta H). Quisqualate is less potent in inhibiting this uptake. In contrast, the chloride- and the calcium-dependent uptake systems do not handle D- and L-aspartate as substrates. A beta H and T beta H are only poor inhibitors of these transporters while quisqualate reduces glutamate uptake almost completely. Kinetic data of all uptake systems were estimated. High and low affinity components of each individual system are demonstrated by Eadie-Hofstee analysis. Hill plots indicate that high and low affinity uptake may be due either to two respective uptake sites for Na(+)-, Cl(-)-, and Ca(++)-dependent glutamate transport, or to two glutamate binding sites for each single transport system with negative cooperativity.

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Astrocytes in cell culture incorporate GM1 ganglioside

Cited by 15 publications

References 34 publications

Incorporation of Very‐Long‐Chain Fatty Acids into Sphingolipids of Cultured Neural Cells

Incorporation of Very‐Long‐Chain Fatty Acids into Sphingolipids of Cultured Neural Cells

Interaction of ganglioside GM1 with the B subunit of cholera toxin modulates growth and differentiation of neuroblastoma N18 cells

Characterization of glutamate uptake systems in astrocyte primary cultures from rat brain

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