Eif4e1b, a germline-specific paralog of the eukaryotic translation initiation factor 4E family, plays a crucial role in oocyte-to-embryo transition (OET) and oogenesis. It is involved in the selective translation of maternal mRNA, which is essential for protein synthesis during early mammalian embryo development. The protein is thought to interact with various mRNA-binding proteins and may be part of a translational regulatory network [1,2,3].

Gene-edited mice, especially those with Eif4e1b maternal deletion (e.g., Eif4e1b-cKO oocytes), have been used to study its function. In these models, maternal deletion of Eif4e1b leads to multiple defects in oogenesis and embryonic developmental competence during OET. The proteins that are crucial for oocyte maturation and embryonic developmental competence are insufficiently synthesized in Eif4e1b-cKO oocytes. Also, loss of Eif4e1b in zebrafish results in reduced histone mRNA levels in early gonads, indicating its role in mRNA storage. In mouse oocytes, knockdown of eIF4E1b in GV-stage oocytes and zygotes significantly reduces the rates of oocyte maturation and blastocyst formation respectively [1,2,4].

In conclusion, Eif4e1b is indispensable for the selective translation activation in mammalian oocytes. Studies using gene-edited mouse models, such as KO or CKO mouse models, have revealed its key role in ensuring zygotic genome activation, oocyte maturation, and early embryonic development. These findings provide new insights into the mammalian maternal-to-zygotic transition and may have implications for understanding infertility and early embryonic development-related disorders [1,2,3,4].

References:

1. Guo, Jing, Zhao, Hailian, Zhang, Jue, Xue, Yuanchao, Lin, Ge. 2023. Selective Translation of Maternal mRNA by eIF4E1B Controls Oocyte to Embryo Transition. In Advanced science (Weinheim, Baden-Wurttemberg, Germany), 10, e2205500. doi:10.1002/advs.202205500. https://pubmed.ncbi.nlm.nih.gov/36755190/

2. Lorenzo-Orts, Laura, Strobl, Marcus, Steinmetz, Benjamin, Dürnberger, Gerhard, Pauli, Andrea. 2023. eIF4E1b is a non-canonical eIF4E protecting maternal dormant mRNAs. In EMBO reports, 25, 404-427. doi:10.1038/s44319-023-00006-4. https://pubmed.ncbi.nlm.nih.gov/38177902/

3. Yang, Guanghui, Xin, Qiliang, Feng, Iris, Wu, Di, Dean, Jurrien. 2023. Germ cell-specific eIF4E1b regulates maternal mRNA translation to ensure zygotic genome activation. In Genes & development, 37, 418-431. doi:10.1101/gad.350400.123. https://pubmed.ncbi.nlm.nih.gov/37257918/

4. Ma, Zengyou, Zhang, Yanyan, Tian, Xueqi, Lu, Wenjie, Peng, Hui. 2025. EIF4E1B interacts with HSPA1A and PPP2CA and is involved in mouse oocyte maturation and early embryonic development. In Theriogenology, 240, 117398. doi:10.1016/j.theriogenology.2025.117398. https://pubmed.ncbi.nlm.nih.gov/40139147/