GSE134537
Genome-wide analysis of mRNA polyadenylation and translation during vertebrate oocyte maturation
Changes in gene expression are required to orchestrate changes in cell state during development. Most cells change patterns of gene expression through transcriptional regulation. In contrast, oocytes are transcriptionally silent and use changes in mRNA poly-A tail length to control protein production. Recent technical advances have enabled genome-wide measurement of poly-A tail length. Poly-A tail lengthening is correlated with translational activation and poly-A tail shortening is correlated with translational repression at a global level during early development. However, it is not clear how poly-A tail changes affect mRNA translation at a global level during vertebrate oocyte maturation. We used TAIL-seq and polyribosome analysis to measure poly-A tail and translational changes during oocyte maturation in Xenopus laevis. We found that the transcriptome undergoes large-scale poly-A and translational changes during oocyte maturation and that poly-A tail length and translation are well-correlated. Interestingly, we found that poly-A tail changes precede translation changes. Additionally, we identified a family of U-rich sequence elements that are enriched near the polyadenylation signal of polyadenylated and translationally activated mRNAs. Interestingly, we found that cytoplasmic polyadenylation is not sufficient to activate translation, which requires a specific density and spacing of U-rich elements. Collectively, our data shows that changes in mRNA polyadenylation are the dominant mechanism controlling protein expression during vertebrate oocyte maturation and that these changes are controlled by a group of cis-acting sequence elements. Our results provide insight into mechanisms of translational control in oocytes and identify novel proteins important for the completion of meiosis. Overall design: poly-A tail lengths and polysome fractions were measured for genome-wide during oocyte maturation in Xenopus laevis