Redundant pathways for Cdc2 activation in Xenopus oocyte: either cyclin B or Mos synthesis.
Xenopus oocytes are arrested in meiotic prophase I. Progesterone induces the resumption of meiotic maturation, which requires continuous protein synthesis to bring about Cdc2 activation. The identification of the newly synthesized proteins has long been a goal. Two plausible candidates have received extensive study. The synthesis of cyclin B and of c-Mos, a kinase that activates the mitogen-activated protein kinase pathway in oocytes, is clearly upregulated by translational control in response to progesterone. Recent studies suggest that ablation of either c-Mos or cyclin B synthesis by antisense oligonucleotides does not block meiotic maturation. Here, however, we show that when both pathways are simultaneously inhibited, progesterone no longer triggers maturation; adding back either c-Mos or cyclin B restores meiotic maturation. We conclude that the specific synthesis of either B-type cyclins or c-Mos, induced by progesterone, is required to induce meiotic maturation. The two pathways seem to be functionally redundant.
Haccard
Olivier
O
Laboratoire de Biologie du Développement, UMR CNRS 7622, UPMC, case 24, 9 quai Saint-Bernard, 75005 Paris, France.
Jessus
Catherine
C
D000818:Animals; D016203:CDC2 Protein Kinase / Q000235:genetics / Q000378:metabolism*; D019926:Cyclin B / Q000235:genetics / Q000378:metabolism; D004789:Enzyme Activation; D005260:Female; D016200:Maturation-Promoting Factor / Q000378:metabolism; D008540:Meiosis / Q000502:physiology; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D016376:Oligonucleotides, Antisense / Q000235:genetics / Q000378:metabolism; D009865:Oocytes / Q000166:cytology / Q000502:physiology*; D011374:Progesterone / Q000378:metabolism; D047428:Protein Kinase Inhibitors / Q000378:metabolism; D017231:Proto-Oncogene Proteins c-mos / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D029867:Xenopus Proteins / Q000235:genetics / Q000378:metabolism*; D014982:Xenopus laevis
D019926:Cyclin B; D016376:Oligonucleotides, Antisense; D047428:Protein Kinase Inhibitors; D029867:Xenopus Proteins; D011374:Progesterone; D017231:Proto-Oncogene Proteins c-mos; D016203:CDC2 Protein Kinase; D016200:Maturation-Promoting Factor; D020928:Mitogen-Activated Protein Kinases