m6A甲基化酶METTL3调控睾丸支持细胞miR-143-3p表达及其在LOH发生中的作用与分子机制

迟发性性腺功能减退症（LOH）是一类严重危害中老年男性生殖健康的高发病，其特征为血清睾酮水平显著降低。当前研究主要集中在流行病学与发生特征方面，发病机制研究相对缺乏，制约了LOH早期诊断和干预治疗的发展。课题组前期研究发现，老龄小鼠睾丸支持细胞（SC）中miR-143-3p表达显著升高，该miRNA可经外泌体介导转运至睾丸间质细胞（LC），靶向LHCGR抑制LC合成睾酮；而下调m6A甲基转移酶METTL3能逆转miRNA-143前体及成熟体表达量的增加。然而，其中的分子机制尚不明确。本项目拟从分子、细胞、动物、临床样本四个层面，采用miCLIP-seq、免疫共沉淀、质谱等技术手段，获得SC中METTL3促进miRNA-143成熟的证据，揭示miRNA-143经外泌体转运，靶向LHCGR抑制睾酮合成的关键信号通路，分析该机制在LOH发生中的作用，为LOH的诊断和治疗提供新靶点和思路。

Late-onset hypogonadism (LOH) is one of the most common disease in middle-aged and elderly men, which seriously endangers their reproductive health. However, current researches mainly focuse on descriptive epidemiology and characteristics of LOH, the pathogenesis is still poorly elucidated, constraining prevention early diagnosis and treatment. Previous work from our research group has demonstrated that miR-143-3p was significantly expressed and secreted in Sertoli cell of aging male mice. Sertoli-derived exosomes mediated the transfer of miR-143-3p from Sertoli cells to Leydig cell, targeting LHCGR protein expression, which decreased the secretion of testosterone. Down-regulation of N6-Methyladenosine methyltransferase Mettl3 could increase the expression of pre-miR-143 and miR-143-3p. However, the roles of METTL3 in regulation of miR-143 maturation still unknown. In this project, we utilized miCLIP-seq, protein co-immunoprecipitation and mass spectrometry (MS) to demonstrate that METTL3 promotes primary miR-143 maturation in Sertoli cells via enhanced m6A modification; And reveal critical signal transduction pathway of miR-143 involved in the secretion of testosterone. Finally, the role and mechanism of METTL3 and miR-143-3p in LOH were analyzed, which may provide new targets and ideas for clinical intervention and the treatment of LOH.