The degradation of maternal RNA-binding protein 4E-T regulates translational activation to ensure maternal-to-zygotic transition in mouse embryos.
TL;DR
Findings suggest that specific maternal RBPs may act as repressors that require precise degradation post-fertilization to relieve translational repression and ensure successful MZT.
Abstract
The maternal-to-zygotic transition (MZT) is essential for early embryonic development, comprising zygotic genome activation (ZGA) as well as the degradation of maternal RNAs and proteins, whereas our understanding of repressors' role in this process remains limited in mammals. In our study, we inhibited protein degradation at the 1-cell stage using the proteasome inhibitor MG132 and observed impaired pre-implantation development and defective ZGA. Proteomic analysis of MG132-treated embryos showed that significantly up-regulated proteins in abundance were enriched for RNA-binding proteins (RBPs). Further functional screening highlighted one critical factor, 4E-T (EIF4ENIF1), whose overexpression caused 2-cell stage arrest and failure of ZGA initiation. Moreover, the abnormal accumulation of 4E-T translationally repressed key factors of the 1-cell embryo, including ZBED3 and KDM4A. Mechanistically, the reprsssion is linked to direct interactions of 4E-T with eIF4E and eIF4E1B. These findings suggest that specific maternal RBPs may act as repressors that require precise degradation post-fertilization to relieve translational repression and ensure successful MZT.