MEK1/2 is a critical regulator of microtubule assembly and spindle organization during rat oocyte meiotic maturation.
MEK (MAPK kinase) is an upstream protein kinase of MAPK in the MOS/MEK/MAPK/p90rsk signaling pathway. We previously reported the function and regulation of MAPK during rat oocyte maturation. In this study, we further investigated the localization and possible roles of MEK1/2. First, immunofluorescent staining revealed that p-MEK1/2 was restricted to the germinal vesicle (GV). After germinal vesicle breakdown (GVBD), p-MEK1/2 condensed in the vicinity of chromosomes and then translocated to the spindle poles at metaphase I, while spindle microtubules stained faintly. When the oocyte went through anaphase I and telophase I, p-MEK1/2 disappeared from spindle poles and became associated with the midbody. By metaphase II, p-MEK1/2 was again localized to the spindle poles. Second, p-MEK1/2 was localized to the centers of cytoplasmic microtubule asters induced by taxol. Third, p-MEK1/2 co-localized with gamma-tubulin in microtubule-organizing centers (MTOCs). Forth, treatment with U0126, a non-competitive MEK1/2 inhibitor, did not affect germinal vesicle breakdown, but caused chromosome mis-alignment in all MI oocytes examined and abnormal spindle organization as well as small cytoplasmic spindle-like structure formation in MII oocytes. Finally, U0126 reduced the number of cytoplasmic asters induced by taxol. Our data suggest that MEK1/2 has regulatory functions in microtubule assembly and spindle organization during rat oocyte meiotic maturation.
Sun
Shao-Chen
SC
Animal Reproduction Institute, Guangxi Key Laboratory of Subtropical Bioresource Conservation and Utilization, Guangxi University, Nanning, China.
Xiong
Bo
B
Lu
Sheng-Sheng
SS
Sun
Qing-Yuan
QY
D000818:Animals; D002070:Butadienes / Q000494:pharmacology; D002453:Cell Cycle / Q000502:physiology; D002478:Cells, Cultured; D048369:MAP Kinase Kinase 1 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D048370:MAP Kinase Kinase 2 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D008540:Meiosis / Q000502:physiology*; D008870:Microtubules / Q000502:physiology*; D009570:Nitriles / Q000494:pharmacology; D009865:Oocytes / Q000502:physiology*; D009866:Oogenesis; D051381:Rats; D017207:Rats, Sprague-Dawley; D008941:Spindle Apparatus / Q000502:physiology*
D002070:Butadienes; D009570:Nitriles; C113580:U 0126; D048369:MAP Kinase Kinase 1; D048370:MAP Kinase Kinase 2