Myogenic differentiation of the muscle clonal cell line BC3H-1 is accompanied by changes in its lipid composition

Phospholipid and neutral lipid composition was studied in the course of myogenic differentiation of the clonal cell line BC3H-1. Total phospholipid content increased during differentiation, predominantly in the major classes of choline and ethanolamine glycerophospholipids. The contents of other lipids, such as triacylglycerols, diminished more than 50% during this period. The content and distribution of fatty acids also underwent marked differentiation-dependent changes. The polyunsaturated (tetrapenta- and hexaenoic) fatty acid species of several phospholipid classes diminished during differentiation, especially those in choline, serine and inositol glycerophospholipids. Most noticeable were the changes in phosphatidylserine; long-chain fatty acids having 20 to 22 carbon atoms and 4 to 6 double bonds decreased from about 30 to about 10 mol%. Although increased levels of saturation in other phospholipid fatty acyl chains appear to accompany the myogenic changes of BC3H-1 cells, some unsaturated fatty acids, such as oleic acid (18:1), increased by as much as 80% during the same period, suggesting the activation of a delta 9 desaturase. Sphingomyelin contained only saturated and monoenoic fatty acids and exhibited a four- to five-fold decrease in its content of monoenoic acyl groups. Diacylglycerols became enriched in arachidonate and docosahexaenoate. The amount of cholesterol and its esters increased slightly during differentiation of BC3H-1 cells. The data show that several metabolic pathways change during myogenic differentiation of the BC3H-1 clonal cell line, particularly de novo biosynthetic pathways, elongation/desaturation reactions, and acyl chain turnover.(ABSTRACT TRUNCATED AT 250 WORDS)