Activation of p34cdc2 kinase by cyclin is negatively regulated by cyclic amp-dependent protein kinase in Xenopus oocytes.
Microinjection of a bacterially expressed stable delta 90 sea urchin cyclin B into Xenopus prophase oocytes, in absence or presence of cycloheximide, provokes the activation of histone H1 kinase and the tyrosine dephosphorylation of p34cdc2. Unexpectedly, when prophase oocytes are submitted to a treatment known to elevate the intracellular cAMP level (3-isobutyl-1-methylxanthine and cholera toxin), delta 90 cyclin has no effect and the oocytes remain blocked in prophase. This inhibition is reverted by the microinjection of the inhibitor of cAMP-dependent protein kinase. When delta 90 cyclin is microinjected into oocytes depleted of endogenous cyclins (cycloheximide-treated metaphase I) and in the presence of a high intracellular concentration of cAMP, p34cdc2 kinase is tyrosine rephosphorylated. Altogether, our results indicate that in Xenopus oocyte, cAMP-dependent protein kinase (A-kinase) controls the formation of the cyclin B/p34cdc2 complex which remains inactive and tyrosine phosphorylated.
Rime
H
H
Laboratoire de Physiologie de la Reproduction, UA-CNRS, INRA 1449, Université P. et M. Curie, Paris, France.
Haccard
O
O
Ozon
R
R
D000818:Animals; D016203:CDC2 Protein Kinase / Q000378:metabolism*; D016213:Cyclins / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D003513:Cycloheximide / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D005260:Female; D008845:Microinjections; D009865:Oocytes / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D011418:Prophase; D047428:Protein Kinase Inhibitors; D011494:Protein Kinases / Q000502:physiology*; D014443:Tyrosine / Q000378:metabolism; D014981:Xenopus
D016213:Cyclins; D047428:Protein Kinase Inhibitors; D014443:Tyrosine; D003513:Cycloheximide; D011494:Protein Kinases; D016203:CDC2 Protein Kinase