Different regulation of phospholipase D activity in glioma C6 cells by sphingosine, propranolol, imipramine and phorbol ester.
In has been found that sphingosine, propranolol, imipramine and phorbol ester (12-O-tetradecanoylphorbol-13-acetate, TPA) have a stimulatory effect on phospholipase D activity in glioma C6 cells. The cells were prelabelled with [1-(14)C]palmitic acid and phospholipase D-mediated synthesis of [(14)C]phosphatidylethanol was measured. The enhancing effect of TPA was almost completely blocked by a specific protein kinase C inhibitor, GF 109203X. In contrast, GF 109203X failed to inhibit the sphingosine, imipramine and propranolol stimulatory effects, indicating that their stimulation was independent of protein kinase C. The effect of TPA on phospholipase D was also blocked by imipramine and propranolol, whereas sphingosine additively potentiated TPA-mediated phospholipase D activity, both at shorter and longer (2-60 min) times of incubation. These results suggest that in glioma C6 cells, sphingosine is not only involved in a different phospholipase D activation than the TPA regulatory system, but also that it operates in a different compartment of the cell.
Bobeszko
M
M
Department of Molecular and Cellular Neurobiology, Nencki Institute of Experimental Biology, 3 Pasteura Street, 02-093 Warsaw, Poland.
Dygas
A
A
Nalepa
I
I
Barańska
J
J
D000818:Animals; D001932:Brain Neoplasms / Q000201:enzymology / Q000473:pathology*; D002451:Cell Compartmentation; D004347:Drug Interactions; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005910:Glioma / Q000201:enzymology / Q000473:pathology*; D007099:Imipramine / Q000494:pharmacology*; D007211:Indoles / Q000494:pharmacology; D007527:Isoenzymes / Q000378:metabolism*; D008301:Maleimides / Q000494:pharmacology; D009363:Neoplasm Proteins / Q000378:metabolism*; D010739:Phospholipase D / Q000378:metabolism*; D011433:Propranolol / Q000494:pharmacology*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000502:physiology; D051381:Rats; D013110:Sphingosine / Q000494:pharmacology*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D014407:Tumor Cells, Cultured / Q000187:drug effects / Q000201:enzymology
D004791:Enzyme Inhibitors; D007211:Indoles; D007527:Isoenzymes; D008301:Maleimides; D009363:Neoplasm Proteins; D011433:Propranolol; D011493:Protein Kinase C; D010739:Phospholipase D; C070515:bisindolylmaleimide I; D013110:Sphingosine; D013755:Tetradecanoylphorbol Acetate; D007099:Imipramine