Dedieu T, Gall L, Crozet N, Sevellec C, Ruffini S
Unité de Biologie de la Fécondation, INRA, Jouy-en-Josas, France.
Mol Reprod Dev. 1996 Nov;45(3):351-8. doi: 10.1002/(SICI)1098-2795(199611)45:3<351::AID-MRD12>3.0.CO;2-1.
Changes in MPF and MAPK activities during meiotic maturation of goat oocytes were investigated. Detection of MPF activity occurred concomitantly with GVBD, increased at MI, decreased during anaphase-telophase I transition, and increased thereafter in MII oocytes. The appearance of MAPK activity was delayed compared to MPF activity. MAPK activity increased after GVBD and persisted during the MI-MII transition. Whether MAPK was implicated in goat oocyte meiotic competence was also investigated by using oocytes from different follicle size categories that arrest at specific stages of the maturation process (GV, GVBD, MI, and MII). Results indicate that the ability of goat oocytes to resume meiosis is not directly related to the presence of Erk2. The ability to phosphorylate MAPK is acquired by the oocyte during follicular growth after the ability to resume meiosis. GVBD-arrested oocytes exhibited a high level of MPF activity after 27 hr of culture. However, 28% of oocytes from this group contained inactive MAPK, and 72% exhibited high MAPK activity. In addition, 29% of GVBD-arrested oocytes contained a residual interphasic network without recruitment of microtubules around the condensed chromosomes; 71% of GVBD-arrested oocytes displayed recruitment of microtubules near the condensed chromosomes and contained asters of microtubules distributed throughout the cytoplasm. These results indicate that oocytes arrested at GVBD were not exactly at the same point in the meiotic cell cycle progression, and suggest that MAPK could be implicated in the regulation of microtubule organization. The data presented here suggest that in goat oocytes, MAPK is not implicated in the early events of meiosis resumption, but rather in post-GVBD events such as spindle formation and MII arrest.
研究了山羊卵母细胞减数分裂成熟过程中MPF和MAPK活性的变化。MPF活性的检测与GVBD同时发生，在MI期增加，在后期-末期I转换期间降低，此后在MII期卵母细胞中增加。与MPF活性相比，MAPK活性的出现延迟。MAPK活性在GVBD后增加，并在MI-MII转换期间持续存在。还通过使用来自不同卵泡大小类别的卵母细胞来研究MAPK是否与山羊卵母细胞减数分裂能力有关，这些卵母细胞在成熟过程的特定阶段（GV、GVBD、MI和MII）停滞。结果表明，山羊卵母细胞恢复减数分裂的能力与Erk2的存在没有直接关系。卵母细胞在卵泡生长期间获得恢复减数分裂能力后获得磷酸化MAPK的能力。培养27小时后，GVBD停滞的卵母细胞表现出高水平的MPF活性。然而，该组中28%的卵母细胞含有无活性的MAPK，72%表现出高MAPK活性。此外，29%的GVBD停滞卵母细胞含有残余的间期网络，在浓缩染色体周围没有微管募集；7l%的GVBD停滞卵母细胞在浓缩染色体附近显示微管募集，并含有分布在整个细胞质中的微管星体。这些结果表明，停滞在GVBD的卵母细胞在减数分裂细胞周期进程中并不完全处于同一点，并表明MAPK可能参与微管组织的调节。此处呈现的数据表明，在山羊卵母细胞中，MAPK不参与减数分裂恢复的早期事件，而是参与GVBD后事件，如纺锤体形成和MII停滞。
