Wnt5a介导PCP信号通路调控Sertoli细胞连接的分子机制研究

Blood-testis barrier (BTB) and apical ES which are synchronized with the crosstalk of Sertoli cell and Sertoli-germ cell are obligatory for spermatogenesis and sperm release conductive to normal pregnancy. Here we show that Wnt5a, a noncanonical Wnt signaling pathway ligand, is predominately expressed in both BTB and apical ES, and it has specific expression pattern with the cycle of seminiferous epithelium. We employed lentivirus-mediated siRNA to knock down Wnt5a efficiently in testis of SD rats and primary Sertoli cells, and further uncovered elongated spermatids lost polarity, and embedded in the seminiferous epithelium, phagosomes were found near the tubule lumen, the junction between Sertoli cells was more tighten. However, the potential molecular mechanism controlling these events have remained largely unexplored. In consideration of close relationship between actin dynamics and Sertoli cell junctions, thus, the aim of this project is to explore that BTB and apical ES expressed Wnt5a regulates actin dynamics through mediating the interaction between the target gene Dvl1 and actin binding protein Eps8, clarifying the molecular mechanism of Wnt5a in Sertoli cell junctions through PCP signaling pathway. Our findings could provide experimental basis for the clinical diagnosis and treatment of male infertility caused by Sertoli cell junction impairment.

Sertoli细胞以及Sertoli细胞与生殖细胞之间构成的血睾屏障和apical ES是精子正常生成和释放的必要前提。课题组前期研究发现，Wnt5a作为非经典Wnt信号通路的配体主要表达于血睾屏障和apical ES，并随着生精上皮周期的变化呈现特定的时空表达模式。利用慢病毒工具敲降SD大鼠睾丸组织和原代Sertoli细胞中的Wnt5a后发现：精子细胞失去极性，滞留于生精上皮中，吞噬体不能被运输至基底部，Sertoli细胞之间的连接更为紧密，但具体机制尚不明确。由于actin的动态变化与Sertoli细胞连接密切相关，因此，本课题旨在探究Wnt5a通过调节下游靶基因Dvl1和actin结合蛋白Eps8之间的相互作用调控actin的动态变化，阐明Wnt5a介导PCP信号通路调控Sertoli细胞连接的分子机制。研究结果将为Sertoli细胞连接功能受损所致的男性不育的临床诊疗提供实验依据。

不孕不育严重危害人类生殖健康，其中男性因素约占50%，精子数量和质量下降是男性不育的关键原因。由Sertoli细胞以及Sertoli细胞与生殖细胞之间所构成的特殊连接结构—血睾屏障和apical ES，是精子正常生成和释放的必要前提。课题组前期研究发现，Wnt5a作为非经典Wnt信号通路的重要配体，在睾丸生精过程中，主要表达于血睾屏障和apical ES，并随着生精上皮周期的变化呈现特定的时空表达模式。利用siRNA敲降SD大鼠睾丸组织和Sertoli细胞中的Wnt5a后发现：精子细胞失去极性，滞留于生精上皮中，吞噬体不能被运输至基底部，Sertoli细胞之间的连接更为紧密，但具体机制尚不明确。由于actin的动态变化与Sertoli细胞连接密切相关，因此，本课题旨在探究Wnt5a通过受体ROR2调控mTORC1和mTORC2之间的平衡，阐明Wnt5a介导PCP信号通路调控Sertoli细胞连接的分子机制。研究结果将为Sertoli细胞连接功能受损所致的男性不育的临床诊疗提供科学的实验依据。