BCAS2 regulates granulosa cell survival via participating in Flt3l mRNA splicing

Granulosa cell proliferation and differentiation are essential for follicle development. Breast cancer amplified sequence 2 (BCAS2) is necessary for spermatogenesis, oocyte development, and maintaining the genome integrity of early embryos in mice. However, the function of BCAS2 in granulosa cells is still unknown. We show that conditional disruption of BCAS2 causes follicles development failure; cell proliferation markers PCNA and Ki67 positive cell ratio are unchanged in granulosa cells. However, specific deletion of BCAS2 causes BrdU positive cell ratio to decrease, cell cycle arrest appearance, DNA damage, and cell apoptosis increase in granulosa cells, RPA1 was abnormally stained in granulosa cells. Furthermore, RNA-Seq results reveal that knockout of BCAS2 results in cellular senescence gene unusual expression. BCAS2 participates in the PRP19 complex to mediate alternative splicing (AS) of E2f3 and Flt3l mRNA to inhibit the cell cycle. Knock down of BCAS2 results in a significantly decrease of BrdU positive cell ratio in Human granulosa-like tumor(KGN) cell line. Thus, BCAS2 regulates granulosa cell proliferation, DNA damage repair, and cell apoptosis. BCAS2 is vital for female fertility. Overall design: BCAS2 was knocked out in ovarian granulosa cells, and 8dpp ovaries were taken to analyze and compare the gene expression profiles of RNA-SEQ data between WT and knockout groups.