Inhibition of phosphatidylcholine and phosphatidylethanolamine biosynthesis by cytochalasin B in cultured glioma cells: Potential regulation of biosynthesis by Ca2+-dependent mechanisms

Tony P. George; Harold W. Cook; David M. Byers; Frederick B.St C. Palmer; Matthew W. Spence

doi:10.1016/0005-2760(91)90219-8

Inhibition of phosphatidylcholine and phosphatidylethanolamine biosynthesis by cytochalasin B in cultured glioma cells: Potential regulation of biosynthesis by Ca²⁺-dependent mechanisms

Tony P. George, Harold W. Cook, David M. Byers, Frederick B.St C. Palmer, Matthew W. Spence

Medicine

Producción científica: Contribución a una revista › Artículo › revisión exhaustiva

17 Citas (Scopus)

Resumen

The major route of phosphatidylcholine (PtdCho) biosynthesis in mammalian cells is the sequence: choline (Cho) → phosphocholine (PCho) → cytidinediphosphate choline (CDP-Cho) → PtdCho. Recently, we have found that intermediates of this pathway are not freely diffusible in cultured rat glioma (C6) cells but are channeled towards PtdCho biosynthesis (George et al. (1989). Biochim. Biophys. Acta 1004, 283-291). Channeling of intermediates in other mammalian systems is thought to be mediated through adsorption of enzymes to membranes and cytoskeletal elements to form multienzyme complexes. In this study, agents which perturb the structure and function of cytoskeletal elements were tested for effects on phospholipid metabolism in glioma cells. The fikament-disrupting agent cytochalasin B (CB), but not other cytochalasins or the microtubule depolymerizer colchicine inhibited PtdCho and phosphatidylethanolamine (PtdEtn) biosynthesis as judged by dose-dependent reduction of labelling from [³H]Cho and [¹⁴C]ethanolamine (Etn). ³²P_i pulse-labeling indicated that CB selectively decreased PtdCho and PtdEtn biosynthesis without affecting synthesis of other phospholipids. Synthesis of water-soluble intermediates of PtdCho metabolism was unaffected but the conversion of phosphoethanolamine to CDP-ethanolamine was reduced by CB. Effects CB on phospholipid biosynthesis were not due to inhibition on glucose uptake as shown by experiments with 2-deoxyglucose, glucose-starved cells and other cytochalsins. Experiments with Ca²⁺-EGTA buffers and digitonin-permeabilized cells, and the Ca²⁺-channel blocker verapamil suggest that effects of CB on PtdCho and PtdEtn biosynthesis are due to alteration of intracellular Ca²⁺. Taken together, these results suggest that CB acts at sites distinct from glucose transport and cellular microfilaments to specifically inhibit PtdCho and PtdEtn biosynthesis by mechanisms dependent on intracellular Ca²⁺.

Idioma original	English
Páginas (desde-hasta)	185-193
Número de páginas	9
Publicación	Biochimica et Biophysica Acta - Molecular and Cell Biology of Lipids
Volumen	1084
N.º	2
DOI	https://doi.org/10.1016/0005-2760(91)90219-8
Estado	Published - jul. 9 1991

Nota bibliográfica

Funding Information:
This work was supported by a Program Grant (PG-16), a scholarship (D.M.B.) and a Career Investigator Award (M.W.S.) from the Medical Research Council of Canada. T.P.G. is a Medical Undergraduate Scholar of the Dalhousie Medical Research Foundation. The expert technical assistance of Mr. Robert Zwicker in culturing cells is gratefully acknowleged,

ASJC Scopus Subject Areas

Biophysics
Biochemistry
Endocrinology

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10.1016/0005-2760(91)90219-8

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George, T. P., Cook, H. W., Byers, D. M., Palmer, F. B. S. C., & Spence, M. W. (1991). Inhibition of phosphatidylcholine and phosphatidylethanolamine biosynthesis by cytochalasin B in cultured glioma cells: Potential regulation of biosynthesis by Ca²⁺-dependent mechanisms. Biochimica et Biophysica Acta - Molecular and Cell Biology of Lipids, 1084(2), 185-193. https://doi.org/10.1016/0005-2760(91)90219-8

Inhibition of phosphatidylcholine and phosphatidylethanolamine biosynthesis by cytochalasin B in cultured glioma cells: Potential regulation of biosynthesis by Ca²⁺-dependent mechanisms. / George, Tony P.; Cook, Harold W.; Byers, David M. et al.
En: Biochimica et Biophysica Acta - Molecular and Cell Biology of Lipids, Vol. 1084, N.º 2, 09.07.1991, p. 185-193.

Producción científica: Contribución a una revista › Artículo › revisión exhaustiva

George, TP, Cook, HW, Byers, DM, Palmer, FBSC & Spence, MW 1991, 'Inhibition of phosphatidylcholine and phosphatidylethanolamine biosynthesis by cytochalasin B in cultured glioma cells: Potential regulation of biosynthesis by Ca²⁺-dependent mechanisms', Biochimica et Biophysica Acta - Molecular and Cell Biology of Lipids, vol. 1084, n.º 2, pp. 185-193. https://doi.org/10.1016/0005-2760(91)90219-8

George TP, Cook HW, Byers DM, Palmer FBSC, Spence MW. Inhibition of phosphatidylcholine and phosphatidylethanolamine biosynthesis by cytochalasin B in cultured glioma cells: Potential regulation of biosynthesis by Ca²⁺-dependent mechanisms. Biochimica et Biophysica Acta - Molecular and Cell Biology of Lipids. 1991 jul. 9;1084(2):185-193. doi: 10.1016/0005-2760(91)90219-8

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abstract = "The major route of phosphatidylcholine (PtdCho) biosynthesis in mammalian cells is the sequence: choline (Cho) → phosphocholine (PCho) → cytidinediphosphate choline (CDP-Cho) → PtdCho. Recently, we have found that intermediates of this pathway are not freely diffusible in cultured rat glioma (C6) cells but are channeled towards PtdCho biosynthesis (George et al. (1989). Biochim. Biophys. Acta 1004, 283-291). Channeling of intermediates in other mammalian systems is thought to be mediated through adsorption of enzymes to membranes and cytoskeletal elements to form multienzyme complexes. In this study, agents which perturb the structure and function of cytoskeletal elements were tested for effects on phospholipid metabolism in glioma cells. The fikament-disrupting agent cytochalasin B (CB), but not other cytochalasins or the microtubule depolymerizer colchicine inhibited PtdCho and phosphatidylethanolamine (PtdEtn) biosynthesis as judged by dose-dependent reduction of labelling from [3H]Cho and [14C]ethanolamine (Etn). 32Pi pulse-labeling indicated that CB selectively decreased PtdCho and PtdEtn biosynthesis without affecting synthesis of other phospholipids. Synthesis of water-soluble intermediates of PtdCho metabolism was unaffected but the conversion of phosphoethanolamine to CDP-ethanolamine was reduced by CB. Effects CB on phospholipid biosynthesis were not due to inhibition on glucose uptake as shown by experiments with 2-deoxyglucose, glucose-starved cells and other cytochalsins. Experiments with Ca2+-EGTA buffers and digitonin-permeabilized cells, and the Ca2+-channel blocker verapamil suggest that effects of CB on PtdCho and PtdEtn biosynthesis are due to alteration of intracellular Ca2+. Taken together, these results suggest that CB acts at sites distinct from glucose transport and cellular microfilaments to specifically inhibit PtdCho and PtdEtn biosynthesis by mechanisms dependent on intracellular Ca2+.",

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