Regulation of mRNA localization during the oocyte-to-embryo transition by regulated mRNA-endoplasmic reticulum association and remodeling of the endoplasmic reticulum

ABSTRACT: As an important post-transcriptional regulatory mechanism, asymmetric localization of mRNAs is essential for cell polarity and cell fate determination during early development. In an effort to understand localization of mRNAs encoding proteasome components during Xenopus oocyte-to-embryo transition, we discovered that the endoplasmic reticulum (ER), which is thought to mainly serve “house-keeping” roles in the cell, plays a multifaceted role in controlling localization of maternal RNAs. Our RNA-seq analysis of fractionated transcripts reveals that more than 40% of RNAs, including proteasome mRNAs, are present on the ER in Xenopus oocytes. After meiotic maturation, a large fraction of ER-associated RNA is released into the cytosol. The release of proteasome RNAs from the ER into the cytosol is conserved during mouse oocyte maturation. Our comparative proteomic analysis and ribonucleoprotein immunoprecipitation demonstrate that the majority of ER-associated RNA-binding proteins (RBPs) remain associated with the ER after oocyte maturation. However, all ER-associated RBPs analyzed exhibit reduced binding to some of their target RNAs after oocyte maturation, providing a mechanistic explanation for the dynamic regulation of RNA-ER association. We further show that the ER is remodeled massively during Xenopus oocyte maturation, leading to the formation of a widespread tubular ER network in the animal hemisphere that is required for the asymmetric localization of proteasome mRNAs in mature eggs. To our knowledge, our findings demonstrate for the first time that dynamic regulation of RNA-ER association and remodeling of the ER are fundamentally important for asymmetric localization of RNAs during development.

INSTRUMENT(S): LTQ Orbitrap Elite

ORGANISM(S): Xenopus Laevis (african Clawed Frog)

TISSUE(S): Egg, Oocyte

SUBMITTER: Hyojeong Hwang  

LAB HEAD: Jing Yang

PROVIDER: PXD033018 | Pride | 2022-12-15

REPOSITORIES: Pride