在辅助生殖技术中，经体外成熟（IVM）培养的卵子其发育能力与临床妊娠率显著低于体内成熟的卵子。我们前期研究发现含有ser325Arg，Gly391Arg和Ser412Pro突变的人源性生长分化因子9（GDF9）蛋白可促进IVM体系中猪卵子和后续胚胎的发育能力，但是野生型的人源性GDF9蛋白无体外活性。根据前期研究基础，我们推测Ser412位点可能是决定人源性GDF9蛋白的体外活性及促卵子发育能力的关键氨基酸位点。但是Ser412Pro突变的重组蛋白通过何种机制实现其体外活性，能否优化IVM培养体系并改善妊娠结局仍需进一步阐明。本课题在前期研究的基础上，拟构建人源性GDF9 Ser412Pro突变重组蛋白，通过研究与受体的亲和力和下游信号通路的影响，对靶细胞（颗粒细胞与卵子）生理功能的促进，对IVM成熟率及后续体外受精后对妊娠结局的改善，阐明其对IVM培养体系的优化作用及其分子机制。

In assisted reproductive techniques (ART), the developmental competence and clinical pregnancy rate of oocytes in vitro maturation (IVM) are much lower than in vivo maturation. We previously found mutant human growth differentiation factor 9 (GDF9) protein containing 3 Residue Chang (ser325Arg, Gly391Arg, Ser412Pro) could improve developmental competence of oocytes and generation of embryos in porcine, while wild type human GDF9 protein was latent. Our scientific hypothesis is: Ser412 plays a critical role in bioactivity of GDF9 and optimizing oocyte developmental competence. But, how does human GDF9 protein containing mutation of Ser412Pro improve its bioactivity? Does this mutant protein optimize IVM system and improve clinical pregnancy outcome? what is the mechanism? In this study, we try to construct human recombinant GDF9 protein containing mutation of Ser412Pro to investigate affinity to its receptor, downstream signaling pathway transduction, effect on physiological functions of target cells (granulosa cells and oocytes), effect on optimizing IVM culture system and subsequent pregnancy outcome after fertilization in vitro. We aim to clarify the effect on optimization of IVM culture system and its molecular mechanism.