Division of Animal and Dairy Sciences, College of Agriculture and Life Sciences, Chungnam National University, Korea, Republic of Korea.
Reproduction. 2022 Feb 24;163(4):233-240. doi: 10.1530/REP-21-0227.
Cytoplasmic polyadenylation element-binding protein 2 (CPEB2) is an mRNA-binding protein that regulates the cytoplasmic polyadenylation of mRNA and is required for tight junction (TJ) assembly in the trophectoderm epithelium during porcine preimplantation development. However, the regulatory mechanism underlying TJ assembly by CPEB2 has not been examined. The aim of this study was to elucidate how Cpeb2 regulates the subcellular localisation and stabilisation of Tjp1 mRNA for TJ biogenesis during mouse preimplantation. CPEB2 was detected in nuclei during the early stages of development and was localised at apical cell membranes from the morula stage onwards. In the Cpeb2 knockdown (KD), we observed reduced blastocyst formation with impaired TJs, defective inner cell mass development in the blastocyst outgrowth assay, and loss of pregnancy after embryo transfer. More importantly, Tjp1 mRNA was localised apically in the outer cells of control morulae but not in the Cpeb2 KD embryos, indicating that CPEB2 mediated the translocalisation of Tjp1 mRNA from the nuclei. Finally, in the control embryos, the length of the Tjp1 mRNA poly (A) tail was varied, while only a single peak was detected in the Cpeb2 KD embryos. These findings suggest that the binding of CPEB2 to the cytoplasmic polyadenylation element in the 3'-UTR can confer stability on Tjp1 mRNA and translational regulation. In summary, we demonstrated for the first time that CPEB2 mediates Tjp1 mRNA stabilisation and subcellular localisation for TJ assembly during mouse blastocyst formation.
细胞质多聚腺苷酸化元件结合蛋白 2（CPEB2）是一种 mRNA 结合蛋白，可调节 mRNA 的细胞质多聚腺苷酸化，并且在猪胚胎植入前发育过程中滋养外胚层的紧密连接（TJ）组装中是必需的。然而，CPEB2 调节 TJ 组装的调控机制尚未被研究过。本研究旨在阐明 Cpeb2 如何调节 Tjp1 mRNA 的亚细胞定位和稳定性，以促进小鼠胚胎植入前 TJ 的生物发生。CPEB2 在早期发育阶段存在于核内，并从桑葚胚阶段开始定位于顶端细胞膜。在 Cpeb2 敲低（KD）中，我们观察到胚胎的囊胚形成减少，TJ 受损，在囊胚外植体生长试验中内细胞团发育不良，胚胎转移后妊娠丢失。更重要的是，Tjp1 mRNA 在对照桑葚胚的外层细胞中定位于顶端，但在 Cpeb2 KD 胚胎中没有，这表明 CPEB2 介导了 Tjp1 mRNA 从核内的易位。最后，在对照胚胎中，Tjp1 mRNA 多聚（A）尾的长度是可变的，而在 Cpeb2 KD 胚胎中只检测到一个单一的峰。这些发现表明，CPEB2 与 3'-UTR 中的细胞质多聚腺苷酸化元件的结合可以赋予 Tjp1 mRNA 稳定性和翻译调节。总之，我们首次证明 CPEB2 介导 Tjp1 mRNA 的稳定和亚细胞定位，以促进小鼠囊胚形成中的 TJ 组装。
