EMC10通过钠/钾-ATP酶在精子功能调控和男性不育发病过程中的作用研究

Our group has identified a new factor, EMC10, which plays an important role in male fertility. The research article regarding EMC10 and male fertility has been accepted by the Journal of Molecular Cell Biology. We found that male mice lacking Emc10 gene are completely sterile. Ablation of EMC10 results in decreased motility, impaired capacitation, impotency of acrosome reaction and abnormal morphology in spermatozoa. EMC10 deficiency also leads to inactivation of the Na/K-ATPase, in turn giving rise to an increased level of intracellular Na+ in spermatozoa, and reduction of HCO3--induced cAMP-dependent protein kinase A (PKA) substrate phosphorylation and protein tyrosine phosphorylation. We observed that EMC10 expression in sperm is positively associated with human sperm motility, and in vitro administration of EMC10 is capable of improving sperm motility in patients with asthenozoospermia. We are looking forward to getting financial support from NSFC. Emc10 testis or epididymis-specific knockout mice will be generated. The levels of EMC10 in serum and seminal plasma of infertile man will be determined. Sperm from infertile patient will be treated by EMC10 protein in vitro. Eventually, the impacts of EMC10 on the regulation of sperm function and the pathogenesis of male infertility will be elucidated, and the potential therapeutic value of EMC10 will be evaluated.

课题组发现了一个在雄性生育中发挥重要作用的新因子：EMC10，研究论文已经被《Journal of Molecular Cell Biology》接收，已明确Emc10基因缺失雄性小鼠完全不育，EMC10缺失导致精子运动力减弱、精子获能受损、顶体反应缺失以及形态学的异常；导致钠/钾-ATP酶失活，引起精子细胞内钠离子水平增加；导致HCO3-诱导的cAMP/PKA信号通路激活受损以及精子获能相关蛋白酪氨酸磷酸化水平的下降。人精子中EMC10的表达与精子的运动力呈正相关性，体外EMC10蛋白刺激能够提高弱精症患者精子的运动能力。课题组期盼得到基金委的资助，通过建立Emc10基因睾丸/附睾特异剔除的小鼠模型，检测不育患者血清以及精浆中EMC10的含量，在体外用EMC10干预不育患者的精子，明确EMC10对精子功能的调控作用及在男性不育发病中的作用，评估EMC10治疗男性不育的潜在价值。

不孕不育是全球范围内严重的公共健康问题，约有10-15%的育龄期夫妇受此困扰，其中男性因素占50%。已有研究证实基因的异常表达是精子发生障碍或成熟异常的重要致病因素。本项目延续上一项国家自然科学基金项目，对EMC10在雄性生育过程中的作用和分子机制进行研究，并初步探索了其临床应用价值。发现：（1）小鼠EMC10存在两种同源异构体，膜型EMC10和分泌型EMC10，且在生殖系统中高表达；（2）在EMC10基因敲除的小鼠模型中，睾丸局部过表达膜型EMC10能够显著提高小鼠的精子活力，而不管是在体内过表达分泌型EMC10，还是体外干预，均不能显著改善精子的活力；（3）人精子中EMC10与ATP1B3的表达水平个体差异较大，两者呈正相关。精浆中分泌型EMC10与精子质量指标无显著相关性，作为分子标志物用于评估精子质量和生育能力意义不大。分泌型EMC10重组蛋白孵育并不能显著改善人精子活力，其在弱精症患者中的治疗价值有限；（4）在生殖细胞中，ATP1B3介导了膜型EMC10对于细胞内Na+的调节，而分泌型EMC10对于ATP1B3的表达和细胞内Na+水平均无影响，这可能是EMC10缺失导致雄性不育的关键分子机制。本课题明确了膜型EMC10在雄性生育中发挥重要作用，为男性不育的诊疗提供潜在的分子靶点，初步完成了计划研究内容，达到了预期目标。