Multifaceted SOX2-chromatin interaction underpins pluripotency progression in early embryos

Pioneer transcription factors (TFs), such as OCT4 and SOX2, play crucial roles in pluripotency regulation. However, the master TF-governed pluripotency regulatory circuitry was largely inferred from cultured cells. In this work, we investigated SOX2 binding from embryonic day 3.5 (E3.5) to E7.5 in the mouse. In E3.5 inner cell mass (ICM), SOX2 regulates the ICM-trophectoderm program but is dispensable for opening global enhancers. Instead, SOX2 occupies preaccessible enhancers in part opened by early-stage expressing TFs TFAP2C and NR5A2. SOX2 then redistributes when cells adopt naive and formative pluripotency by opening enhancers or poising them for further rapid activation. Hence, multifaceted pioneer TF–enhancer interaction underpins pluripotency progression in embryos, including a state in E3.5 ICM that bridges totipotency and pluripotency. Overall design: By employing CUT&RUN,ATAC-seq, ChIP-seq and RNA-seq, we systematically examined the genome wide SOX2 cromatin binding an function in mouse erly embryos and mESC cell lines and differentiated cells.