Center for Reproductive Medicine, Cheeloo College of Medicine, Shandong University, Jinan, China.
Advanced Medical Research Institute, Shandong University, Jinan, China.
FASEB J. 2022 Jun;36(6):e22357. doi: 10.1096/fj.202101950R.
The reproductive life span of females is largely determined by the number and quality of oocytes. Previously, we identified MEIOK21 as a meiotic recombination regulator required for male fertility. Here, we characterize the important roles of MEIOK21 in regulating female meiosis and oocyte number and quality. MEIOK21 localizes at recombination sites as a component of recombination bridges in oogenesis like in spermatogenesis. Meiok21 female mice show subfertility. Consistently, the size of the primordial follicle pool in Meiok21 females is only ~40% of wild-type females because a great number of oocytes with defects in meiotic recombination and/or synapsis are eliminated. Furthermore, the numbers of primordial and growing follicles show a more marked decrease in an age-dependent manner compared with wild-type females. Further analysis shows Meiok21 oocytes also have reduced rates of germinal vesicle breakdown and the first polar body extrusion when cultured in vitro, indicating poor oocyte quality. Additionally, Meiok21 oocytes have more chromosomes bearing a single distally localized crossover (chiasmata), suggesting a possible defect in crossover maturation. Taken together, our findings indicate critical roles for MEIOK21 in ensuring the number and quality of oocytes in the follicles.
女性的生殖寿命在很大程度上取决于卵母细胞的数量和质量。此前，我们鉴定出 MEIOK21 是一种减数分裂重组所必需的调控因子，对于雄性的生育能力是必需的。在这里，我们描述了 MEIOK21 对调节雌性减数分裂和卵母细胞数量和质量的重要作用。MEIOK21 作为重组桥的一个组成部分，在卵发生中定位于重组位点，就像在精子发生中一样。Meiok21 雌性小鼠表现出亚生育能力。一致地，Meiok21 雌性的原始卵泡池大小仅为野生型雌性的~40%，因为大量存在减数分裂重组和/或联会缺陷的卵母细胞被消除。此外，与野生型雌性相比，原始卵泡和生长卵泡的数量在年龄依赖性方式下表现出更为显著的减少。进一步的分析表明，Meiok21 卵母细胞在体外培养时也具有较低的生发泡破裂和第一极体挤出率，表明卵母细胞质量较差。此外，Meiok21 卵母细胞具有更多携带单个远侧定位交叉（交叉）的染色体，表明交叉成熟可能存在缺陷。总之，我们的发现表明 MEIOK21 在确保卵泡中卵母细胞的数量和质量方面起着关键作用。
