Figure 6. Distinct signaling requirements for inducing and maintaining naive human pluripotency.

Model summarizing the main findings from this study: dual MEK and ERK inhibition promotes efficient primed-to-naive resetting in combination with TNKS, PKC, ROCK inhibitors, and activin A (PXGGY/A). These p-ERK^LOW naive hESCs resemble previously described 5i/L/A naive hESCs (Theunissen et al., 2016; Theunissen et al., 2014) and exhibit a human ICM-like identity based on comparison to 3D-cultured human embryos (Xiang et al., 2020). They can transition into a pre-implantation EPI state with elevated levels of ERK phosphorylation in the presence of RAF, TNKS, PKC, and ROCK inhibitors (AXGY). These cells retain expression of typical naive markers but also display increased levels of global DNA methylation and HERVH transcription. Global DNA methylation and HERVH transcription are further increased in the primed pluripotent state, which corresponds to the post-implantation epiblast at E12–14.