Lysophosphatidylethanolamine acyltransferase activity is elevated during cardiac cell differentiation

We examined if elevation in lysophosphatidylethanolamine acyltransferase ac tivity was associated with elevation in phosphatidylethanolamine content du ring differentiation of P19 teratocarcinoma cells into cardiac myocytes. P1 9 cells were induced to undergo differentiation into cardiac myocytes by th e addition of 1% dimethylsulfoxide to the medium. Immunofluorescence micros copy revealed the presence of striated myosin at 8 days post-dimethylsulfox ide addition confirming differentiation into cardiac cells. The content of phosphatidylethanolamine was increased 2.1-fold (P < 0.05) in differentiate d cells compared to undifferentiated cells, whereas the content of phosphat idylcholine was reduced 29% (P < 0.05). There were no alterations in the po ol sizes of other phospholipids, including cardiolipin. The relative abunda nce of fatty acids in phospholipids of P19 cells was 18:1 > 18:0 > 16:1 = 1 8:2 > 16:0 = 14:0 > 20:4 and differentiation did not affect the relative am ounts of these fatty acids within individual phospholipids. When cells were incubated with [1,3-H-3] glycerol, radioactivity incorporated into phospha tidylethanolamine was elevated 5.8-fold, whereas radioactivity incorporated into phosphatidylcholine was unaltered. Ethanolaminephosphotransferase, ch olinephosphotransferase and membrane CTP:phosphocholine cytidylyltransferas e activities were elevated in differentiated cells compared to undifferenti ated cells, whereas membrane and cytosolic phospholipase A? activities were unaltered. Lysophosphatidylethanolamine acyltransferase activities were el evated 2.4-fold (P < 0.05). Lysophosphatidylcholine acyltransferase, monoly socardiolipin acyltransferase, acyl-Coenzyme A synthetase and acyl-Coenzyme A hydrolase activities were unaltered in differentiated cells compared to undifferentiated cells. We postulate that during cardiac cell differentiati on, the observed elevation in lysophosphatidylethanolamine acyltransferase activity accompanies the elevation in phosphatidylethanolamine mass, possib ly to maintain the fatty acyl composition of this phospholipid within the m embrane. (C) 2000 Elsevier Science B,V. All rights reserved.