Abstract
Growing evidence indicates that the deterioration of egg quality caused by postovulatory ageing significantly hampers embryonic development. However, the molecular mechanisms by which postovulatory ageing leads to a decline in oocyte quality have not been fully characterized. In this study, we observed an accelerated decay of maternal mRNAs through RNA-seq analyses in postovulatory-aged (PostOA) oocytes. We noted that these downregulated mRNAs should be degraded during the 2-cell stage. Proteomic analyses revealed that the degradation of maternal mRNAs is associated with the accumulation of DCP1A. The injection of exogenous Dcp1a mRNA or siRNA into MII stage oocytes proved that DCP1A could accelerate the degradation of maternal mRNAs. Additionally, we also found that SPDL1 is crucial for maintaining spindle/chromosome structure and chromosome euploidy in PostOA oocytes. Spdl1-mRNA injection remarkably recovered the meiotic defects in PostOA oocytes. Collectively, our findings provide valuable insights into the molecular mechanisms underlying postovulatory ageing.