人卵子体外成熟过程中组蛋白乙酰化的动态变化模式

目的：组蛋白乙酰化与有丝分裂过程中的多个染色质相关事件有关，但是它在哺乳动物减数分裂过程中的作用仍不清楚。本研究通过观察人卵子体外成熟过程中不同阶段的组蛋白H3K9乙酰化变化模式，以探讨组蛋白乙酰化在减数分裂过程中的作用。方法：我们选择在我院进行单精子显微注射（Intracytoplasmicsperminjection，ICSI）的病人，共收集用于GV期卵子25个，MI期卵子28个用于本研究。将其中一部分直接用4％多聚甲醛固定，另一部分体外培养成熟至MII期，再用4％多聚甲醛固定。采用免疫荧光染色检测不同发育时期卵子的组蛋白H3K9乙酰化状态。结果：免疫荧光染色结果显示，GV期的卵子可检测到明显的H3K9乙酰化，MI期和MII期的卵子的H3K9乙酰化程度逐渐减弱。结论：人类卵子在成熟过程中会发生组蛋白H3K9乙酰化水平的逐渐降低，可能与减数分裂过程中特定的染色体分离、基因表达的重新编程密切相关。

Changes in Histone Acetylation during In-Vitro Maturation of Human Oocytes

Objective： Histone acetylation is associated with a diversity of chromatin-related processes in mitosis. However, its roles in mammalian oocyte meiosis are largely unknown. In the present study, we first observed the acetylation changes during human oocyte maturation in order to investigate the role of histone acetylation change in meiosis. Methods： In this study, immature oocytes （25 GV-stage oocytes and MI stage oocytes） were collected from patients undergoing ICSI in our hospital. Some of oocytes were directly fixed in 4% paraformaldehyde in PBS. Others will be fixed in 4% paraformaldehyde in PBS after completing maturation when cultured in IVM-medium. The patterns of H3K9 acetylation in immature and mature oocytes were observed by immunofluorescent staining and scanning confocal microscopy. Results： Immunocytochemical analyses revealed that the all of the lysines examined were highly acetylat- ed in the germinal vesicle stage. In the first metapbase, the lysines near the N-terminal end, H3K9 was decreased but still present. The acetylations were further decreased at the second metaphase than that in the first metaphase. Conclusion： Histone acetylation obviously decreased during in vitro maturation of human ooeytes, which suggesting the meiosis specific regulation of histone acetylation. Also, the underacetylation may be involved in meiosis specific chromosomal segregation.