Differential regulation of phosphatidylcholine biosynthesis by 12-O-tetradecanoylphorbol-13-acetate and diacylglycerol in NG108-15 neuroblastoma x glioma hybrid cells.
12-O-Tetradecanoylphorbol-13-acetate (TPA), a tumor promoter and potent activator of protein kinase C, stimulates [3H]choline incorporation into phosphatidylcholine (PtdCho) in NG108-15 cells (Liscovitch, M., Freese, A., Blusztajn, J. K. and Wurtman, R. J. (1986) J. Neurochem. 47, 1936-1941). In the present study we demonstrate that two cell-permeant diacylglycerols, sn-1-oleoyl-2-acetylglycerol and sn-1,2-dioctanoylglycerol, also stimulate [3H]choline incorporation into PtdCho. However, the effect of diacylglycerol is additional to that produced by a maximally effective concentration of TPA (0.5 microM), suggesting that the two agents may not act via the same mechanism. In addition, the protein kinase inhibitor 1-(5-isoquinolinesulfonyl)-2-methylpiperazine dihydrochloride (at 200 microM) inhibits the action of TPA by 59% while not affecting that of diacylglycerol. Finally, preincubation of the cells with TPA (0.1 microM) for 24 h reduces protein kinase C activity in the cells and completely abolishes the effect of additional TPA on choline incorporation. In contrast, diacylglycerol-induced stimulation of PtdCho biosynthesis was not inhibited in the cells that were desensitized to TPA. These results suggest that the effect of the two cell-permeant diacylglycerols on PtdCho biosynthesis either is not mediated by protein kinase C activation, or, is mediated by a TPA-insensitive isoenzyme of protein kinase C.
Liscovitch
M
M
Department of Hormone Research, Weizmann Institute of Science, Rehovot, Israel.
Slack
B
B
Blusztajn
J K
JK
Wurtman
R J
RJ
D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D000818:Animals; D002794:Choline / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D004075:Diglycerides / Q000378:metabolism / Q000493:pharmacokinetics*; D005910:Glioma; D005989:Glycerides / Q000493:pharmacokinetics*; D006822:Hybrid Cells / Q000187:drug effects / Q000378:metabolism*; D007546:Isoquinolines / Q000494:pharmacology; D009447:Neuroblastoma; D010713:Phosphatidylcholines / Q000096:biosynthesis*; D010879:Piperazines / Q000494:pharmacology; D011493:Protein Kinase C / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000493:pharmacokinetics*; D014407:Tumor Cells, Cultured / Q000378:metabolism
D004075:Diglycerides; D005989:Glycerides; D007546:Isoquinolines; D010713:Phosphatidylcholines; D010879:Piperazines; C044295:1,2-dioctanoylglycerol; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; C038237:1-oleoyl-2-acetylglycerol; D011493:Protein Kinase C; D002794:Choline; D013755:Tetradecanoylphorbol Acetate