Role of in maternal mRNA turnover.

Removal of poly(A) tail is an important mechanism controlling eukaryotic mRNA turnover. The major eukaryotic deadenylase complex CCR4-NOT contains two deadenylase components, CCR4 and CAF1, for which mammalian CCR4 is encoded by or paralogs. We show that apparently supplies the majority of CCR4 in the maternal CCR4-NOT in mouse, hamster, and bovine oocytes. Deletion of yielded viable mice, but females exhibited ∼40% smaller litter size. The main onset of the phenotype was post-zygotic: fertilized eggs developed slower and arrested more frequently than eggs, suggesting that maternal CNOT6L is necessary for accurate oocyte-to-embryo transition. Transcriptome analysis revealed major transcriptome changes in ovulated eggs and one-cell zygotes. In contrast, minimal transcriptome changes in preovulatory oocytes were consistent with reported mRNA dormancy. A minimal overlap between transcripts sensitive to decapping inhibition and loss suggests that decapping and CNOT6L-mediated deadenylation selectively target distinct subsets of mRNAs during oocyte-to-embryo transition in mouse.