CNOT3-Dependent mRNA Deadenylation Safeguards the Pluripotent State

Poly(A) tail length and mRNA deadenylation play important roles in gene regulation. However, how they regulate embryonic development and pluripotent cell fate is not fully understood. Here we present evidence that CNOT3-dependent mRNA deadenylation governs the pluripotent state. We show that CNOT3, a component of the Ccr4-Not deadenylase complex, is required for mouse epiblast maintenance. It is highly expressed in blastocysts and its deletion leads to peri-implantation lethality. The epiblast cells in Cnot3 deletion embryos are quickly lost during diapause and fail to outgrow in culture. Mechanistically, CNOT3 C terminus is required for its interaction with the complex and its function in embryonic stem cells (ESCs). Furthermore, Cnot3 deletion results in increases in the poly(A) tail lengths, half-lives, and steady-state levels of differentiation gene mRNAs. The half-lives of CNOT3 target mRNAs are shorter in ESCs and become longer during normal differentiation. Together, we propose that CNOT3 maintains the pluripotent state by promoting differentiation gene mRNA deadenylation and degradation, and we identify poly(A) tail-length regulation as a post-transcriptional mechanism that controls pluripotency. •CNOT3 is required for mouse epiblast maintenance during early development•CNOT3 C-terminal domain is necessary for the maintenance of the pluripotent state•CNOT3 promotes differentiation gene mRNA deadenylation and degradation•mRNA poly(A) tail regulation plays a critical role in pluripotency In this article, Hu and colleagues showed that CNOT3, a component of the Ccr4-Not deadenylase complex, is required for the maintenance of the pluripotent state in mouse epiblast and embryonic stem cells. They found that CNOT3 promotes differentiation gene mRNA deadenylation and degradation, and post-transcriptionally regulates the gene expression program in pluripotent cells.