DNA损伤修复基因MSH5在卵巢早衰发病中的作用和机制研究

Premature ovarian failure (POF) is a hypergonadotropic disorder characterized by cessation of menstruation occurs before the age of 40 years. Approximately 1% -2% of women in childbearing age are affected by POF and demonstrate with infertility, which adversely affect women’s physical and psychological health. Through the whole exome sequencing performed in a Chinese POF pedigree, we identified the homozygous mutation D487Y in MSH5 as a candidate variation for POF. Our study has showed that MSH5 might not only participate in meiotic homologous recombination in oocytes, but also involve in the DNA repair process in oocytes, granulosa cells and theca cells from primordial to antral follicles. Moreover, mutation D487Y has been found to adversely affect the MSH5’s response to DNA double strand breaks. So we hypothesize that dysfunctional DNA repair caused by MSH5 mutation might lead to a greater rate of follicle loss through atresia, finally causing POF. In the project, we want to illustrate the influence of MSH5 D487Y on oogenesis and follicle development using the knock-in mouse with the mutation. Besides that, through mutation screening for MSH5 in sporadic POF patients and subsequently functional studies, we hope to confirm the relationship between MSH5 mutation and POF, furthermore the causative mechanism.

卵巢早衰（POF）是指女性40岁之前出现高促性腺激素性卵巢功能减退，是育龄期女性常见的生殖内分泌疾病之一，发病率1%-2%，严重影响女性的生理和心理健康。通过对1个中国汉族卵巢早衰家系进行全外显子组测序，我们发现了位于MSH5基因的纯合错义突变D487Y。前期研究结果提示MSH5不仅参与卵母细胞第一次减数分裂前期的染色体联会和同源重组过程，而且参与不同发育时期卵母细胞及其支持细胞的DNA损伤修复过程，而突变D487Y能够影响MSH5对DNA双链损伤的修复功能。因此，MSH5基因突变导致的DNA损伤修复功能缺陷可能是POF的致病机制之一。本项目拟借助Msh5 点突变小鼠模型研究Msh5突变D487Y对卵子发生和卵巢功能的影响及机制，同时在散发性POF患者中进行MSH5基因突变筛查和相关功能研究，进一步明确MSH5基因突变与POF的相关性及其致病机制。

卵巢早衰（POF）是指女性40岁之前出现高促性腺激素性卵巢功能减退，是育龄期女性常见的生殖内分泌疾病之一，发病率1%-2%，严重影响女性的生理和心理健康。通过对1个中国汉族非近亲婚配POF家系进行全外显子组测序，我们发现了位于MSH5基因的纯合错义突变D487Y。该突变位于MSH5的DNA结合功能域内，在多物种间高度保守，酵母的同源位点突变可严重影响孢子生成，提示该位点对生殖细胞的形成具有重要作用。我们随后通过体外实验证实该突变能够影响MSH5对双链DNA损伤的修复作用，并构建了点突变小鼠模型。通过小鼠表型分析发现，该突变对小鼠体型和生长发育无明显影响，但纯合突变雌鼠出生后卵母细胞进行性丢失，不孕，与人类POF的临床表现非常相似，进而明确该突变是POF的发病原因。该研究进一步拓宽了POF的致病基因谱，为POF遗传病因学诊断提供了可靠依据，也为POF基因诊断工具的研发提供了素材。由于MSH5是重要的DNA同源重组相关基因，该研究再次强调了DNA损伤修复机制，尤其是同源重组修复机制在卵巢功能维持和POF发病中的作用。