Insulin-like growth factor 1, insulin, and progesterone induce early and late increases in Xenopus oocyte sn-1,2-diacylglycerol levels before meiotic cell division.
After a 3 to 6 hour incubation, addition of progesterone (the most effective), insulin-like growth factor 1 (IGF-1; the second most effective), or insulin induces meiotic cell division in Xenopus oocytes. Measurement of an endogenous activator of protein kinase C, sn-1,2-diacylglycerol (DAG), by an enzymatic method recording mass demonstrates that all three hormones alter DAG levels. Five seconds after addition, only progesterone transiently reduces DAG levels by about 25%. At 15 minutes after addition, all three hormones produce a peak of DAG (115% to 160% of control values), with the more effective hormones producing a larger increase in DAG. Insulin produces the smallest DAG increase, but the DAG release is longer lasting. Finally, all three hormones induce a second peak in DAG levels just before white spot appearance (at 0.85 GVBD50, where 1.0 GVBD50 is when 50% of the cells have divided). With these data and since an activator of protein kinase C, a phorbol ester, has been found to induce meiosis, the kinase may play a role in early proliferative events at the plasma membrane and in late events at the nucleus.
Stith
B J
BJ
Department of Biology, University of Colorado, Denver 80217-3364.
Kirkwood
A J
AJ
Wohnlich
E
E
D000818:Animals; D004075:Diglycerides / Q000378:metabolism*; D005260:Female; D007328:Insulin / Q000494:pharmacology*; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D008540:Meiosis / Q000187:drug effects*; D009865:Oocytes / Q000187:drug effects / Q000378:metabolism; D011374:Progesterone / Q000494:pharmacology*; D014981:Xenopus
C011439:1,2-diacylglycerol; D004075:Diglycerides; D007328:Insulin; D011374:Progesterone; D007334:Insulin-Like Growth Factor I