A functional neddylation pathway underlies oocyte quality and aging

摘要 与她们的整个寿命相比，妇女的生育窗口期很短。生育率通常达到顶峰 25岁左右，但随后卵母细胞质量和卵母细胞数量的损失导致生殖能力下降 然后在51岁左右绝经这成为一个健康问题，因为妇女越来越多地推迟 生育，直到她们超过“高龄产妇”（AMA）（即，年龄35岁以上）。AMA女性有风险 非整倍体增加，导致流产、出生缺陷、早产和其他高危妊娠。 这主要是由卵母细胞质量缺陷驱动的，因为女性接受人工生殖技术 使用年轻的捐赠卵子在所有年龄段都有相似的怀孕率。虽然定义不明确，但卵母细胞质量下降， 可以归因于几个因素，包括有缺陷的染色体结构，蛋白质稳态，和线粒体， 但卵母细胞质量随时间推移而丧失的原因尚不清楚。我们最近创造了一种新的卵母细胞特异性 翻译后修饰（PTM）所需的中心酶（UBA 3）的条件性敲除（ocKO）， neddylation。Neddylation将小的泛素样蛋白NEDD 8共价连接到靶蛋白上， E1-E2-E3酶级联调节蛋白质结构、功能、稳定性和亚细胞定位。的 neddylation在卵泡发生期间雌性生育力和卵母细胞发育中的作用尚不清楚。我们 初步数据显示，Uba 3 ocKO雌性小鼠是不育的， 成年后，卵母细胞染色体结构发生变化，减数分裂恢复，线粒体 活性，提示卵母细胞质量下降。由于neddylation调节线粒体结构和功能， 对于某些细胞，线粒体功能被认为是卵母细胞质量的关键驱动因素，我们的中心假设是 neddylation是卵泡发生过程中卵母细胞发育所必需的，部分是通过调节 线粒体功能本项目的目的是（1）确定neddylation的丧失如何改变 （2）证明neddylation活性随卵母细胞老化而下降。的 这些目标的结果将首次表明，neddylation与线粒体功能障碍有关， 卵母细胞和neddylation效率的变化可能会驱动卵母细胞老化的方面。此外，这些研究 将成为未来研究的基础，以确定是否neddylation可以在ART设置中利用 作为提高老年妇女卵子中卵母细胞质量的一种手段。

ABSTRACT Women have a short reproductive window compared to their overall lifespan. Fertility usually peaks around age 25, but a subsequent loss of oocyte quality and oocyte numbers leads to reproductive decline followed by menopause around age 51. This becomes a health concern as women increasingly delay childbearing until they are past ‘advanced maternal age’ (AMA) (i.e., ages 35+). AMA women are at risk of increased aneuploidy that leads to miscarriage, birth defects, premature birth and other high-risk pregnancies. This is primarily driven by defects in oocyte quality, as women undergoing artificial reproductive technologies using young donor eggs have similar pregnancy rates at all ages. While poorly defined, declines in oocyte quality can be attributed to several factors, including defective chromosome structure, proteostasis, and mitochondria, but much of why oocyte quality is lost overtime is unknown. We recently generated a novel oocyte-specific conditional knockout (ocKO) for a central enzyme (UBA3) required for the post-translational modification (PTM), neddylation. Neddylation covalently attaches the small ubiquitin-like protein, NEDD8, to target proteins via an E1-E2-E3 enzymatic cascade to regulate protein structure, function, stability, and subcellular localization. The role of neddylation in female fertility and oocyte development during folliculogenesis is not known. Our preliminary data show that Uba3 ocKO female mice are sterile, show depletion of most oocytes by young adulthood, and have oocytes with changes in chromosome structure, meiotic resumption, and mitochondrial activity, suggestive of a loss in oocyte quality. As neddylation regulates mitochondrial structure and function in some cells, and mitochondrial function is thought to be a key driver of oocyte quality, our central hypothesis is that neddylation is required for the development of oocytes during folliculogensis in part by regulating mitochondrial function. The Aims of this project are designed to (1) determine how loss of neddylation alters mitochondrial function in oocytes and (2) demonstrate that neddylation activity declines with oocyte aging. The results from these Aims will show for the first time that neddylation is linked to mitochondrial dysfunction in oocytes and that changes in neddylation efficiency may drive aspects of oocyte aging. In addition, these studies will form the foundation of future studies to determine whether neddylation could be exploited in the ART setting as a means to increase oocyte quality in eggs of older women.