Induction of precocious germinal vesicle breakdown (GVB) by GVB-incompetent mouse oocytes: possible role of mitogen-activated protein kinases rather than p34cdc2 kinase.

摘要: In contrast to fully grown mouse oocytes, growing oocytes released from their preantral follicles are not capable of resuming meiosis spontaneously. However, when these denuded incubated for 2-3 days in control medium and then treated with okadaic acid, 95% undergo precocious germinal vesicle breakdown (GVB) chromosome condensation within 24 h. This study shows that both events apparently occur through a p34cdc2 kinase-independent pathway, since activity this kinase was detected only after the had undergone acid-stimulated GVB. contrast, microtubule-associated or mitogen-activated protein (MAP) kinases 1 2 were activated before GVB level correlated percentage undergoing GVB, suggesting may promote under experimental conditions. addition, it is shown MAP accumulate during normal oocyte growth vivo, but cultured vitro even become competent Unlike p34cdc2, accumulation requires close physical interactions between granulosa cells necessary GVB-competent. Therefore, actually involved induction maturation, acquisition competence oocyte-autonomous activator(s) rather than themselves.