Progesterone triggers the rapid activation of phospholipase D in the amphibian oocyte plasma membrane when initiating the G2/M transition.
Previous reports indicate that, in the Rana pipiens oocyte, progesterone triggers a rapid rise in 1,2-diacylglycerol (DAG) derived from phosphatidylcholine (PC) in the plasma membranes. This DAG transient, which appears and is terminated within 60-90 s, is derived both from a phospholipase which we assumed to be phospholipase C and from sphingomyelin (SM) synthase. We now find that progesterone stimulates PC and DAG turnover primarily via the phospholipase D (PLD) and phosphatidic acid phosphohydrolase (PAP) pathways as well as via the SM-ceramide pathway. Rana oocytes were prelabeled with [3H]choline chloride under conditions in which about 70% is incorporated into PC of the plasma membrane of the intact oocyte or with [3H]lysoplatelet activating factor (1-O-octadecyl-sn-glycero-3-phosphocholine, lysoPAF) which is selectively incorporated into plasma membrane PC. Progesterone induced the release of [3H]choline from intact oocytes into the medium within 60-90 s. This choline release was dose-dependent and was not inhibited by a putative PC-specific phospholipase C inhibitor, D609. Progesterone also induced a transient rise in [3H]lysoPAF-derived [3H]DAG within 1-2 min followed by a rise in [3H]PA. In the presence of 20 mM ethanol, progesterone stimulated formation of [3H]lysoPAF-derived phosphatidylethanol, indicating progesterone activation of PC-specific PLD and concomitant formation of PA. A DGK inhibitor (D102) reduced the level of [3H]PA, produced a sustained rise in [3H]DAG and was a weak inducer of meiosis in oocytes not exposed to progesterone. A PA phosphohydrolase inhibitor (propranolol) elevated [3H]PA and completely inhibited the progesterone-induced rise in DAG. Progesterone thus acts at oocyte plasma membrane receptors to release PC-derived DAG via both SM synthase and PC-PLD. The duration of the DAG signal is regulated by the coordinate action of DGK and PAP.
Kostellow
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AB
Department of Physiology and Biophysics, Albert Einstein College of Medicine, Bronx, New York 10461, USA.
Ma
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Morrill
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GA
D000818:Animals; D001952:Bridged-Ring Compounds / Q000494:pharmacology; D002453:Cell Cycle / Q000187:drug effects*; D002462:Cell Membrane / Q000201:enzymology; D002794:Choline / Q000378:metabolism; D019852:Diacylglycerol Kinase; D004075:Diglycerides / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D004958:Estradiol / Q000494:pharmacology; D009636:Norbornanes; D009865:Oocytes / Q000201:enzymology* / Q000378:metabolism; D010711:Phosphatidate Phosphatase / Q000378:metabolism / Q000494:pharmacology; D010712:Phosphatidic Acids / Q000378:metabolism; D010713:Phosphatidylcholines / Q000378:metabolism; D010714:Phosphatidylethanolamines / Q000378:metabolism; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D010739:Phospholipase D / Q000378:metabolism*; D010767:Phosphorylcholine / Q000378:metabolism; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism / Q000494:pharmacology; D011374:Progesterone / Q000494:pharmacology*; D011894:Rana pipiens; D013109:Sphingomyelins / Q000378:metabolism; D013859:Thiocarbamates; D013871:Thiones / Q000494:pharmacology; D017855:Transferases (Other Substituted Phosphate Groups) / Q000378:metabolism
D001952:Bridged-Ring Compounds; D004075:Diglycerides; D009636:Norbornanes; D010712:Phosphatidic Acids; D010713:Phosphatidylcholines; D010714:Phosphatidylethanolamines; D010726:Phosphodiesterase Inhibitors; D013109:Sphingomyelins; D013859:Thiocarbamates; D013871:Thiones; D010767:Phosphorylcholine; D011374:Progesterone; D004958:Estradiol; C046498:tricyclodecane-9-yl-xanthogenate; D017853:Phosphotransferases (Alcohol Group Acceptor); D019852:Diacylglycerol Kinase; D017855:Transferases (Other Substituted Phosphate Groups); C070186:phosphatidylcholine-ceramide phosphocholine transferase; D010711:Phosphatidate Phosphatase; D010739:Phospholipase D; D002794:Choline