Elevation in phosphatidylethanolamine is an early but not essential event for cardiac cell differentiation

The biosynthesis of phosphatidylethanolamine was examined during differenti ation of P19 teratocarcinoma cells into cardiac myocytes, P19 cells were in duced to undergo differentiation into cardiac myocytes by the addition of d imethyl sulfoxide to the medium. Immunofluorescence labeling confirmed the expression of striated myosin 10 days postinduction of differentiation. The content of phosphatidylethanolamine increased significantly within the fir st 2 days of differentiation, [1,3-H-3]Glycerol incorporation into phosphat idylethanolamine was increased 7.2-fold during differentiation, indicating an elevation in de novo synthesis from 1,2-diacyl-sn-glycerol. The mechanis m for the increase in phosphatidylethanolamine levels during cardiac cell d ifferentiation was a 2.8-fold increase in the activity of ethanolaminephosp hotransferase, the 1,2-diacyl-sn-glycerol utilizing reaction of the cytidin e 5'-diphosphate-ethanolamine pathway of phosphatidylethanolamine biosynthe sis. Incubation of P19 cells with the phosphatidylethanolamine biosynthesis inhibitor 8-(4-chlorophenylthio)-cAMP inhibited the differentiation-induce d elevation in phosphatidylethanolamine levels but did not affect the expre ssion of striated myosin. The results suggest that elevation in phosphatidy lethanolamine is an early event of P19 cell differentiation into cardiac my ocytes, but is not essential for differentiation to proceed. (C) 2000 Acade mic Press.