BCAS2调控卵子发生的作用机制研究

Mammalian oogenesis is regulated by sophisticated gene expression, the deficiency of which leads to female infertility and various birth defects. As an important dimension of gene regulation, alternative splicing greatly diversifies the gene products and thus their functions. However, the functions and molecular mechanisms of alternative splicing in oogenesis are largely unknown. BCAS2 is one of the core components of the Prp19 complex and plays important roles in pre-mRNA splicing. We previously reported that BCAS2 was involved in spermatogenesis by regulating the alternative splicing of key genes in spermatogonia. Based on these results, we intend to conditionally delete BCAS2 during oogenesis at different time points to investigate the physiological function of BCAS2 in mouse oogenesis. By using in vivo and in vitro methods, we seek to identify the target mRNAs of BCAS2, screen out the interactive RNA binding proteins or splicing factors with BCAS2, and analyze and confirm the alternative splicing events regulated by BCAS2 in mouse oocyte. Our results would not only gain novel insights to mammalian oogenesis, but also provide theoretical basis for human infertility diagnosis and treatment.

哺乳动物卵子发生受到精确的基因表达调控，该过程异常会导致女性不孕不育和婴儿出生缺陷。可变剪接作为一种重要的转录后调控基因表达的方式，极大地增加了基因产物种类和功能的多样性，但其在卵子发生中的功能和作用机制还鲜有报道。BCAS2是Prp19剪接复合体的核心组分之一，参与了前体mRNA的剪接等重要事件。我们前期的研究结果表明，BCAS2通过调控精原干细胞中关键基因的可变剪接参与精子发生。本研究拟利用条件性基因敲除手段在卵子发生的不同时间点对BCAS2进行特异敲除，研究BCAS2在小鼠卵子发生中的生理功能。进一步通过体内和体外研究相结合的方式分析和验证卵母细胞中BCAS2调控的可变剪接事件、鉴定BCAS2的靶标mRNAs以及筛选与BCAS2相互作用的RNA结合蛋白或者剪接因子。本项目研究成果不仅可以为理解哺乳动物卵子发生提供新的认识，且可为不孕不育的诊疗提供理论依据。

可变剪接（AS）是调节器官发生和生殖生育的重要作用机制。BCAS2是PRP19剪接复合体的核心成分之一，并通过调控雄性小鼠的可变剪接参与减数分裂的启动。然而，BCAS2 在小鼠卵子发生中的作用在很大程度上仍然是未知的。在这项研究中，我们发现BCAS2在原始卵泡的卵母细胞中高度表达。Vasa-Cre介导的BCAS2的缺失导致卵母细胞质量变差、卵子发生异常和卵泡发育异常。小鼠卵母细胞中BCAS2的缺失导致991个可变剪接事件发生异常改变，这些事件对应了706个基因，包括与卵子发生和纺锤体组装相关的 Pabpc1l、Nobox、Zfp207、Mybl2、Prc1和 Spc25这些重要的功能性基因。此外，BCAS2的缺失导致小鼠卵母细胞中PRP19复合体的核心组分被降解。这些结果表明BCAS2在小鼠卵母细胞发育过程中通过PRP19剪接复合体参与调控功能性基因的可变剪接。