FAM175A基因在卵巢早衰发病中的作用及机制研究

Premature ovarian failure (POF) refers to the exhaustion of women’s ovary reserve before the age of 40 years. The patients manifest hypergonadotrophic amenorrhea, infertility and a series of perimenopause-related clinical manifestations. POF is one of the common diseases of reproductive endocrinology in child-bearing aged women and greatly jeopardizes physiological and psychological health of women with POF. POF patients present a high heterogeneity in the etiology and recent studies suggest gene defects in the DNA damage repair pathway may cause POF. The results of our previous research showed that the knockout female mice of Fam175a gene, which is a DNA repair gene, had significantly reduced fertility with similar manifestations of human POF. Furthermore, we have identified one novel heterozygous mutation L243V in the Chinese POF patients. The present results suggest that FAM175A gene is involved in the pathogenesis of POF through affecting the process of DNA repair. Based on the previous results, we will systematically explore the function and mechanism of the Fam175a gene in female mice reproduction by using knockout mice. Furthermore, we will carry out mutational screening of FAM175A gene in more POF patients, study the functional changes of the mutations in vitro and finally clarify the role and mechanism of FAM175A gene in the POF development. The current study will contribute to the demonstration of the etiology of POF from the new view of DNA repair defects, and show great significance about the prevention and early intervention of POF.

卵巢早衰（POF）是指女性40岁之前出现卵巢功能衰竭，表现为高促性腺激素性闭经、不孕及围绝经期症状，是育龄期女性常见的生殖内分泌疾病之一，严重影响女性的生理和心理健康。POF病因高度异质，新近研究提示DNA损伤修复基因功能缺陷可能是POF的致病原因之一。我们的前期结果显示，DNA损伤修复基因Fam175a敲除雌鼠生育力明显降低，有类似人类POF疾病表现，并在POF病人中筛查出新发杂合突变L243V，提示FAM175A基因可能通过影响DNA损伤修复参与POF的发生。在前期结果基础上，本项目通过基因敲除小鼠系统研究Fam175a基因缺失对雌鼠生殖功能的影响及机制，并进一步在POF病人中对该基因进行突变筛查及体外功能研究，最终阐明FAM175A基因在POF发病中的作用及机制。本研究有助于从DNA损伤修复缺陷这一新的角度理解POF的发病机制，对于POF的预防和早期干预具有重要的理论和实践意义。

卵巢早衰（POF）是指女性40岁之前出现卵巢功能衰竭，是育龄期女性常见的生殖内分泌疾病。POF病因异质，进展迅速且无有效治疗手段，病因研究对于其预防、早期诊断和治疗具有重要意义。目前研究表明DNA损伤修复缺陷可能是POF的致病原因之一，但具体致病机制尚不清楚。本项目通过动物实验发现，DNA损伤修复相关基因Fam175a敲除影响了小鼠的DNA损伤修复功能，对环磷酰胺引起DNA损伤的敏感性增高，导致卵巢中卵泡过早耗竭，引起卵巢早衰的发生，为POF发生的DNA损伤修复缺陷理论提供了实验证据。我们进一步通过POF患者基因测序发现，FAM175A基因存在突变c.C727G (p.L243V)，但功能实验证实该突变未影响细胞对DNA损伤的敏感性和修复能力，也不影响G2-M细胞周期检验点的调控，说明该突变不是导致POF的常见原因。由于我们在POF患者中没有发现FAM175A基因的致病性突变，因此我们增加了另一个DNA损伤修复基因FANCL的突变筛查，发现了两个新发杂合移码突变c.1048_1051delGTCT (p.Gln350Valfs*18) 和c.739dupA (p.Met247Asnfs*4)，这两个突变不但影响了蛋白定位，而且使FANCL蛋白泛素连接酶功能丧失，导致单倍剂量不足，造成DNA损伤修复能力异常，引起POF的发生。本研究进一步将DNA损伤修复机制与卵巢功能联系起来，证实了DNA损伤修复基因缺陷在POF发病中的重要作用，有助于为早期亚临床阶段POF及卵巢功能储备降低的女性提供诊疗咨询和生育指导。