Protein kinase C initially inhibits the induction of meiotic cell division in Xenopus oocytes.
We have used one activator and two inhibitors of protein kinase C (PKC) to examine the role of this enzyme in the induction of meiotic cell division. At 1 U/ml, phosphatidylcholine-specific phospholipase C increases DAG, alters intracellular pH and inhibits the induction of meiosis by insulin or progesterone. However, when added about 1.6 h after progesterone, the enzyme speeds the induction of cell division. Microinjection of inhibitor peptide (19-36) of PKC has little effect on progesterone action but stimulates the induction of meiosis by insulin. When the inhibitor peptide is injected about 2h after insulin addition, the peptide inhibits. A second PKC inhibitor, staurosporine, decreases PKC-dependent intracellular pH and in vitro oocyte PKC activity. At similar concentrations, staurosporine stimulates insulin or progesterone action, but, when added after about 2 h, the drug inhibits induction by insulin. We conclude that PKC is initially inhibitory to the induction of meiotic cell division but then may become synergistic.
Stith
B J
BJ
Department of Biology, University of Colorado, Denver 80217-3364.
Goalstone
M L
ML
Kirkwood
A J
AJ
D000470:Alkaloids / Q000494:pharmacology; D000818:Animals; D002455:Cell Division / Q000187:drug effects*; D004075:Diglycerides / Q000378:metabolism; D004357:Drug Synergism; D006863:Hydrogen-Ion Concentration / Q000187:drug effects; D007328:Insulin; D008540:Meiosis / Q000187:drug effects*; D009865:Oocytes; D011374:Progesterone / Q000037:antagonists & inhibitors; D011493:Protein Kinase C / Q000494:pharmacology*; D019311:Staurosporine; D013997:Time Factors; D014981:Xenopus
C011439:1,2-diacylglycerol; D000470:Alkaloids; D004075:Diglycerides; D007328:Insulin; D011374:Progesterone; D011493:Protein Kinase C; D019311:Staurosporine