MiR23b-27b-24 Cluster在卵泡发育中的作用机制研究

Polycystic ovary syndrome(PCOS), featured by hyperandrogenemia, is the most common endocrinopathy in women of reproductive age. Previous genome-wide association studies of PCOS from our group have demonstrated Chr9q22.32 is one of the susceptibility loci. Chr9q22.32 contains gene C9orf3 and miRNA23b-27b-24 cluster; the latter three miRNAs cooperate with each other to regulate downstream targeted genes. We screened miRNA23b-27b-24 cluster region and found several nucleotide mutations and real-time PCR discovered that miRNA23b-27b-24 had a lower expression in PCOS serum and granulosa cells. By in situ hybridisation miR-23b is found expressed in oocyte, granulosa cells and theca cells in mouse ovary. Moreover, miR23b and miR27b became inactive in granulosa cells when cultured with high concentration of testosterone. Thus, we presume that miRNA23b-27b-24 may have function in folliculogenesis, and next we plan to study: 1) Exploring the functions of miRNA23b-27b-24 in folliculogenesis by in-vitro and in-vivo experiments; 2) Figuring out whether cluster miRNA23b-27b-24 is regulated by testosterone during folliculogenesis; 3) Fine mapping the causal variants impacting miRNA23b-27b-24 expression in PCOS patients. Overall, this project highlights miRNA functions in folliculogenesis and PCOS aetiology studies, and will provide new clue for PCOS targeted therapy.

多囊卵巢综合征（PCOS）是以雄激素增高为特点的常见妇科疾病，前期本课题组发现Chr9q22.32是PCOS易感区域之一，该区域包含miRNA23b-27b-24 cluster编码序列。MiRNA在PCOS中的作用机制尚无报道，已知miRNA23b-27b-24成簇协同作用，但在卵泡发育中的作用不详。PCOS患者该区域多发碱基突变，血清和颗粒细胞中miRNA23b-27b-24表达降低，定位发现miR23b在小鼠卵巢多种细胞中表达，雄激素处理的颗粒细胞miR23b、miR27b表达明显降低。以上结果提示miRNA23b-27b-24可能参与卵泡发育过程，据此假设，本课题将1）研究miR23b-27b-24 cluster对卵泡发育的影响；2）明确雄激素是否通过调控miR23b-27b-24表达参与卵泡发育调控；3）明确PCOS患者中miRNA23b-27b-24碱基突变的影响。

多囊卵巢综合征是以雄激素增高、胰岛素抵抗为主要特点的常见妇科疾病，前期本课题组发现Chr9q22.32是PCOS易感区域之一，该区域包含miRNA23b-27b-24 cluster编码序列，其在PCOS患者中表达降低且存在多发突变，而目前无相应的功能机制研究。因此本项目拟利用卵巢细胞体外培养及miRNA敲除小鼠研究miRNA23b-27b-24 cluster在PCOS生殖与代谢异常中的作用与分子机制。在本项目的资助与支持下，我们发现miRNA可以通过不同的靶基因，参与细胞与细胞之间的交互作用，影响类固醇激素合成酶相关基因的表达网络，进而调节卵巢膜间质细胞雄激素的合成与分泌。 miRNA23b-27b-24 cluster全敲小鼠出现糖耐量受损，在高脂饮食状态下更为严重，卵巢表现为一定程度的膜间质细胞增厚，其对应的生殖与代谢调控网络（氨基酸与脂代谢以及卵巢激素合成通路）发生显著改变。经生物信息学分析发现当miRNA对应的种子序列发生突变时，细胞之间的信号转导、能量代谢等均发生显著改变。该课题的实施为解析GWAS易感区域的miRNA在PCOS发病中的作用提供了新的理论依据，为PCOS 的治疗从 miRNA 途径提供新的靶点。