Effects of the phorbolester TPA and of the ionophore A 23187 on phospholipase A2 and C activities in the mouse epidermal cell line HEL-30.
The 12-O-tetradecanoylphorbol-13-acetate (TPA)- or ionophore A 23187-induced release of 14C-arachidonic acid from prelabeled murine HEL-30 keratinocytes was studied in vitro. Starting 8 min after drug treatment, a linear increase in the arachidonic acid content in the extracellular medium was observed with a concomitant loss of label in cellular phosphatidylcholine and phosphatidylinositol, but not in phosphatidylethanolamine and phosphatidylserine. No increase in intracellular diacylglycerol and phosphatidic acid was observed. The TPA-induced arachidonic acid release was inhibited by fluocinolone acetonide. The results indicate a direct activation of phosphatidylcholine- and phosphatidylinositol-specific phospholipases A2 by TPA and A23187. Cells prelabeled with 3H-choline released choline, choline phosphate and CDP-choline upon TPA but not upon A 23187 treatment. This could indicate activation of a phospholipase C-type enzyme by the phorbol ester. However, concomitant generation of diacylglycerol and phosphatidic acid was not detected.
D000818:Animals; D016718:Arachidonic Acid; D001095:Arachidonic Acids / Q000378:metabolism*; D000001:Calcimycin / Q000494:pharmacology*; D002273:Carcinogens; D002460:Cell Line; D015232:Dinoprostone; D004789:Enzyme Activation; D004817:Epidermis / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D051379:Mice; D010740:Phospholipases / Q000378:metabolism*; D010741:Phospholipases A / Q000378:metabolism*; D054467:Phospholipases A2; D010743:Phospholipids / Q000378:metabolism; D011458:Prostaglandins E / Q000096:biosynthesis; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D010738:Type C Phospholipases / Q000378:metabolism*
D001095:Arachidonic Acids; D002273:Carcinogens; D010743:Phospholipids; D011458:Prostaglandins E; D016718:Arachidonic Acid; D000001:Calcimycin; D010740:Phospholipases; D010741:Phospholipases A; D054467:Phospholipases A2; D010738:Type C Phospholipases; D015232:Dinoprostone; D013755:Tetradecanoylphorbol Acetate