N6-methyladenosine modulate second cell fate decision by enhancing mRNA stability of pivotal transcription factors during primitive endoderm development [GLORI]

Transcription factors (TFs) have key roles in cell fate determination, and are rapidly upregulated to fulfill developmental functions. During second cell fate decisions in pre-implantation embryonic development, upregulated key TFs, including GATA6 and NANOG, drive the differentiation and functional establishment of primitive endoderm (PrE) and epiblast (EPI) cells. However, how the embryo achieves this swift TF upregulation and the precise molecular mechanisms underlying specific TF initiation remain unclear. In this study, we showed how N6-methyladenosine (m6A) affected embryo and embryoid differentiation. Using two types of extended pluripotent mouse embryonic stem cells with in vivo embryonic and extraembryonic potency-extended pluripotent stem cells (EPSCs) and totipotent blastomere-like cells (TBLCs) alongside mouse embryos, we observed that the m6A writers METTL3 and VIRMA were essential for PrE development. Mechanistically, globally increased mRNA stability occurred during embryo development - mediated by m6A modification. Specifically, m6A enhanced key regulator stability during PrE differentiation, such as Gata6, by interacting with the m6A reader IGF2BP3, thereby promoting protein production and ultimately impacting on cell fate decisions. Our results suggest that post-transcriptional mRNA regulation is a pioneering mechanism governing second cell fate decisions, and highlights the molecular mechanisms underlying mouse embryogenesis.