Complementary Activity of ETV5, RBPJ, and TCF3 Drives Formative Transition from Naive Pluripotency.

Abstract

The gene regulatory network (GRN) of naïve mouse embryonic stem cells (ESC) must be reconfigured to enable lineage commitment. TCF3 sanctions rewiring by suppressing components of the ESC transcription factor circuitry. However, TCF3 depletion only delays, and does not prevent, transition to formative pluripotency. Here we delineate additional contributions of the ETS-family transcription factor ETV5 and the repressor RBPJ. In response to ERK signalling, ETV5 switches activity from supporting self-renewal and undergoes genome relocation linked to commissioning of enhancers activated in formative epiblast. Independent up-regulation of RBPJ prevents re-expression of potent naïve factors, TBX3 and NANOG, to secure exit from the naïve state. Triple deletion of Etv5, Rbpj and Tcf3 disables Manuscript ESC, such that they remain largely undifferentiated and locked in self-renewal even in the presence of differentiation stimuli. Thus genetic elimination of three complementary drivers of network transition stalls developmental progression, emulating environmental insulation by small molecule inhibitors.