雌激素通过抑制gsdf调控罗非鱼卵原细胞增殖与分化的分子机制

卵原（干）细胞作为鱼类卵巢中唯一能进行有丝分裂的生殖细胞，其增殖与分化的分子调控机制还鲜有报道。我们在尼罗罗非鱼构建雌激素不足模型，发现卵原细胞增殖，卵母细胞减少；gsdf是雄性性别决定通路的关键基因，但其仍在卵原细胞周围的体细胞表达，gsdf在雌激素不足时的表达水平显著升高，且启动子上存在雌激素应答元件。据此提出雌激素通过抑制gsdf的表达促进卵原细胞分化进入卵子发生，gsdf是调控卵原细胞增殖与分化的关键生长因子。本项目拟解析雌激素和Gsdf在卵原细胞增殖分化的作用以及它们之间的调控关系；采用组学分析筛选雌激素和gsdf调控卵原细胞增殖分化的候选基因，通过基因编辑证实它们在卵原细胞命运决定中的功能；建立卵原细胞体外培养体系，并进一步阐明雌激素和gsdf对体外培养卵原细胞增殖分化的调控。该研究有助于深化我们对鱼类卵原细胞增殖与分化的分子调控机制的认识，为鱼类繁殖控制技术的开发奠定基础。

Oogonia including female germ stem cell is the only germ cells that can undergo mitosis in female fish. The molecular regulatory of oogonia proliferation and differentiation is largely unknown. Previously, we found that a number of oogonia and the decreased number of oocytes were observed in estrogen deficiency ovaries. Gsdf is critical for male tilapia sex determination, however, it was also expressed in the somatic cells surrounding oogonia. gsdf was significantly increased in the estrogen deficiency ovary and there exist estrogen responsive element in the promoter of gsdf. Based on these results, we proposed that estrogen could promote the entry of oocytes into oogenesis by inhibiting the expression of gsdf, and the microenvironment of gsdf was important for oogonia maintenance. In this project, the roles and regulatory relationship between estrogen and gsdf regulating the proliferation and differentiation of oogonia will be studied. The candidate genes regulating the proliferation and differentiation of oogonia by estrogen and gsdf will be screened by transcriptome analysis. The function of the candidate genes will be investigated by gene editing. Finally, the best conditions for in vitro culture of oogonia will be explored and it will be used for further clarifying the role of estrogen and gsdf. Therefore, this study is helpful to deepen our understanding of the molecular regulatory mechanism of oogenesis, especially the proliferation and differentiation maintenance of oogonia. The data has potential application in controlling reproduction of economic fish in aquaculture.