Stimulation of phospholipid metabolism in embryonic muscle cells treated with phospholipase C.

AUTOR(ES)
RESUMO

Phospholipid metabolism is dramatically stimulated in cultured myogenic cells in which cell fusion was inhibited with phospholipase C (phosphatidylcholine choline-phosphohydrolase; EC 3.1.4.3). Phospholipase C was active under the culture conditions as shown by the degradation of exogenous phosphatidylcholine. Rates of incorporation of 32Pi and [methyl-3H]choline into lipids were about 5-fold greater in phospholipase-treated cells than in either untreated fusing cells or untreated cells prevented from fusing by calcium deprivation. The greatest stimulation in the phospholipase C-treated cultures occurred with synthesis of phosphatidylcholine and sphingomyelin; synthesis of phosphatidylinositol and cardiolipin was not stimulated. Degradation of cellular [32P]phosphatidylcholine and appearance in the culture medium of the degradation product [32P]phosphocholine were both increased. Levels of total cellular phospholipids and of individual phospholipid classes were similar in control and phospholipase-treated cells. The results suggest that the membrane phospholipid composition in myogenic cells is controlled by a regulatory mechanism which increases the synthesis of phospholipids that are degraded in the presence of the phospholipase.

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