PABPN1 promotes meiotic maturation of oocytes by interacting with PAPOLA

Poly(A) polymerase alpha (PAPalpha ), as the specific mRNA polyadenylation enzyme in the cytoplasm of mammalian oocytes, is essential for oocytes to exclude the first polar body. However, PAPalpha knockout did not affect germinal vesicles breakdown (GVBD) of oocytes, and the mechanism needs to be further explored. In this study, we identified that PAPalpha work together with poly(A)-bound RNA binding protein PABPN1 to promote the rupture of germinal vesicles in mammalian oocytes. The protein level of Pabpn1 gradually increases with the meiotic maturation of oocytes. The oocytes specifically knocked out Pabpn1 at the primary follicle stage could develop into the fully grown (FGO) stage, but hardly could enter into the meiotic process. The activated form of CDK1 was injected into Pabpn1-null oocytes, the oocytes could enter into meiotic process. The translational activity of Pabpn1-null oocytes was significantly lower than that of wild-type oocytes during meiosis. In particular, the expression level of protein (BTG4 and CDC25), which were essential for the meiotic maturation of oocytes, were significantly decreased. Therefore, during the oocyte meiosis process, PABPN1 and PAPalpha jointly promote the oocyte to enter the meiosis process. Examination of WT and Pabpn1-null transcriptome in oocytes