BCAS2是一个多功能蛋白，参与前体RNA的剪接和DNA损伤修复等过程，其生理功能研究非常具有挑战性。申请人最近发现母源BCAS2通过DNA损伤修复维持小鼠着床前胚胎基因组稳定（Development，2015）；还发现BCAS2通过前体mRNA选择性剪接调控小鼠精原干细胞减数分裂启动（Nature Communications，2017）；也发现BCAS2缺失导致胚胎死于E5.5-6.5天和ES细胞不能建立。本项目准备利用诱导性敲降ES细胞系结合BCAS2不同片段的挽救实验，研究BCAS2是否通过pre-mRNA剪接调控小鼠ES细胞增殖和DNA损伤修复；同时利用敲除小鼠研究BCAS2在围植入期小鼠胚胎发育的作用机理。该研究不仅可以揭示BCAS2在小鼠ES细胞和围植入期胚胎中的功能机制，还可能发现RNA剪接和DNA损伤修复之间的关系；同时为不育不孕等生殖相关疾病和干细胞等研究提供参考。

BCAS2 is a small protein conserved in organisms and may play important roles in several processes including pre-mRNA splicing and DNA damage. It is a great challenge to investigate the roles of BCAS2 in physiological conditions. Previously, our researches showed that BCAS2 protects the genomic integrity of mouse preimplantation embryos by DNA damage response pathway (Development, 2015), and is also involved in alternative mRNA splicing in mouse spermatogonia and the transition to meiosis, male fertility (Nature Communications, 2017). In addition, we found BCAS2 depletion results mouse embryonic lethality at E5.5-6.5 and the failure of establishing ES cells. At present project, through inducible BCAS2 knock down ES cells and combined with truncated BCAS2 rescue experiments, we will examine whether BCAS2 is involved in the proliferation and DNA damage by regulating alternative pre-mRNA splicing in mouse ES cells. Using the hints from mouse ES cells, we will also address how BCAS2 regulates mouse peri-implantation development. This project will illustrate the role and mechanism of BCAS2 in mouse ES cells and peri-implantation development, thus contributing to early embryonic development, ES cell and reproductive biology.