Acquisition of maturational competence in growing oocytes correlates with their ability to active MAP kinase

哺乳动物卵母细胞的减数分裂成熟受细胞周期分子Cdc2激酶和MAP激酶的控制。在本研究中，我研究了Cdc2激酶和MAP激酶的激活能力与卵母细胞生长过程中减数分裂能力的获得之间的关系。对发育不全的卵母细胞进行体外培养，诱导其成熟。1)从不同直径（0.5 ~ 6.0 mm）的猪腔卵泡中收集生长和完全成熟的卵母细胞，进行体外培养。完全成熟的卵母细胞（120-125 μm）具有完全成熟到中期II的能力，能够激活Cdc2和MAP激酶。相反，生长中的卵母细胞恢复减数分裂的能力有限，却没有这种能力。然而，细胞周期蛋白B1分子确实积累，在培养的卵母细胞中出现磷酸化的无活性形式p34^<cdc2>。直径为110 μm的卵母细胞恢复了减数分裂，但在中期停止。卵母细胞能够更多地激活Cdc2激酶，尽管它们似乎没有建立MAP激酶激活途径。这些结果表明，猪卵母细胞在最终生长阶段获得了激活Cdc2激酶的能力，并建立了mek - map -激酶通路，以获得完全的减数分裂能力。2) MAP激酶的活性形式（pMAPK）定位于中期I的浓缩染色体周围。在后期I和末期I的进程中，pMAPK在细长纺锤体的中间区检测到。在减数分裂I/减数分裂II过渡过程中，MAP激酶活性的抑制抑制了染色体分离、第一极体发射和中期II纺锤体的形成。这些结果表明纺锤体相关的pMAPK在减数分裂I/减数分裂II转变过程中起重要作用。3)猪和牛早期窦卵泡卵母细胞在添加次黄嘌呤的培养基中生长良好，部分卵母细胞在培养8 ~ 16 d后获得减数分裂能力。PP1/PP2A抑制剂诱导生长中的卵母细胞中MAP激酶的快速激活。一些处理过的卵母细胞成熟到中期II。少

Meiotic maturation of mammalian oocytes is under the control of cell cycle molecules Cdc2 kinase and MAP kinase. In the present study, I investigated the relationship between the ability to activate Cdc2 kinase and MAP kinase and the acquisition of meiotic competence during oocyte growth. In vitro growth culture of incompetent growing oocytes was also conducted to induce their maturation.1) Growing and fully grown pig oocytes were collected from antral follicles of various diameters (0.5-6.0 mm) and cultured in vitro. Fully grown oocytes (120-125 μm) which have full competence to mature to metaphase II had the ability to activate both Cdc2 and MAP kinase. In contrast, growing oocytes which have limited competence to resume meiosis had no such ability. Cyclin B1 molecules did accumulate, however, with phosphorylated inactive forms of p34^<cdc2> appearing in the cultured oocytes. Growing oocytes of 110 μm in diameter resumed meiosis but arrested at metaphase I. The oocytes were capable o … More f activating Cdc2 kinase, although they did not appear to have established a MAP kinase-activating pathway. These results suggest that pig oocytes acquire the ability to activate Cdc2 kinase and then establish the MEK-MAP-kinase pathway for full meiotic competence during the final growth phase.2) Active forms of MAP kinase (pMAPK) was localized around condensed chromosomes at metaphase I. During the progression of anaphase I and telophase I pMAPK was detected at the mid-zone of the elongated spindle. The inhibition of MAP kinase activity during the meiosis I/meiosis II transition suppressed chromosome separation, first polar body emission and formation of the metaphase II spindle. These results suggest that the spindle-associated pMAPK plays an important role in the events occurring during the meiosis I/meiosis II transition.3) Growing pig and bovine oocytes from early antral follicles grew efficiently in hypoxanthine-supplemented medium and some of them acquired the meiotic competence after 8-16 days of culture. Inhibitors of PP1/PP2A induced a rapid activation of MAP kinase in growing oocytes. Some of the treated oocytes matured to metaphase II. Less