短尾精子症候选致病基因QRICH2在精子鞭毛发育中的作用与机制研究

Male infertility is a complex and multifactorial disease, and it is estimated that the genetic alteration account for about 15% of the risk of the incidence. With the rapid development of assisted reproductive technology (ART), the accurate diagnosis of genetic factors in male infertility is significant to avoid the inheritance of genetic defects. In this study, we investigated a family with immotile short-tail sperm defect. We found that the proband had a homozygous nonsense mutation of QRICH2 gene, and his parents have heterozygous mutations. It was suggested that QRICH2 may be the pathogenic gene of the proband. To further confirm the pathological role of QRICH2 in the pathogenesis of the phenotype, we plan to carry out further studies to seek more evidence on the participation of QRICH2 in the development of sperm tail structure, and to investigate the underlying mechanism of the potential role of QRICH2 in the development of sperm tail structure, and how the mutations of QRICH2 contribute to spermatogenic failure. The studies include: (1) Investigating the mutations of QRICH2 gene in more patients with short-tail sperm defect and normal controls, to further confirm that QRICH2 is the pathogenic gene of short-tail sperm defect; (2) Analyzing the interaction of QRICH2 and AKAP4 to reveal the role of QRICH2 in the development of sperm tail structure (3) Establishing the QRICH2 knockout mice model to verify the important role of QRICH2 in the development of sperm tail structure and whether its mutation can cause short-tail sperm defect leading to infertility. It can be predcited that the results of the study will provide complete evidence chain for the participation of QRICH2 in the development of sperm tail structure, and make us understand the function pathway and mechanism of QRICH2 in the development of sperm tail structure. Furthermore, this study is hoped to confirm the effect of QRICH2 mutation on short-tail sperm defect leading to infertility, which will be of significance to understand the genetic factor with respect to idiopathic male infertility.

男性不育为一类复杂的多因素疾病，其中遗传因素约占15%。随着辅助生殖技术的迅速发展，为避免遗传缺陷垂直传递，因此对男性不育遗传病因的诊断显得尤为重要。本研究调查了一个不动短尾精子症家系，发现先证者存在QRICH2基因的一个纯合无义突变,导致该基因的翻译提前终止。提示QRICH2可能为该先证者的致病基因。鉴于此，我们将调查更多的短尾精子症患者以及正常对照组的QRICH2基因突变情况，进一步证实QRICH2为短尾精子症的致病基因；通过研究QRICH2与AKAP4的相互作用，揭示QRICH2在精子尾部结构发育过程中的作用机制；建立QRICH2的敲除小鼠模型，进一步证实QRICH2在精子尾部结构发育过程中的重要作用，明确其突变是否可导致短尾精子症进而引起不育，并对其机制进行详细研究。通过探知QRICH2基因在精子尾部发育过程中的重要作用，可以深入了解该基因的突变对男性不育遗传病因的贡献及相关机制。

异常的精子鞭毛会损害精子活力，导致男性不育，但目前发现的存在于多种鞭毛形态异常的基因只能解释少数情况下MMAF的发病机制。在这里，我们鉴定了两个近亲家系的MMAF不育男性的QRICH2纯合子功能缺失突变，并对其功能进行了定性。值得注意的是，利用CRISPR-Cas9技术构建的Qrich2敲除(KO)雄性小鼠呈现MMAF表型和不育性。为阐明Qrich2在精子鞭毛形成中的作用机制，我们对KO和野生型小鼠睾丸进行了蛋白质组学分析。体外实验表明，QRICH2通过稳定和增强与鞭毛发育相关蛋白的表达参与精子鞭毛发育。我们的研究结果强烈提示，人类QRICH2基因突变可导致MMAF男性不育，并且QRICH2对精子鞭毛形成至关重要。