Prolonged Mek1/2 suppression impairs the developmental potential of embryonic stem cells

摘要

Concomitant activation of the Wnt pathway and suppression of Mapk signaling by two small molecules in the presence of LIF (2i/L) induces a naïve state in mouse embryonic stem cells (ESCs) that resembles the inner cell mass (ICM) of the pre-implantation embryo. Since the ICM exists only transiently in vivo, it remains unclear how sustained propagation of naïve ESCs in vitro affects their stability and functionality. Here we show that prolonged culture of male ESCs in 2i/L results in irreversible epigenetic and genomic changes that impair their developmental potential. Additionally, we find that female ESCs cultured in conventional serum/LIF (S/L) media phenocopy male ESCs cultured in 2i/L. Mechanistically, we demonstrate that Mek1/2 inhibition is predominantly responsible for these effects, in part through downregulation of DNA methyltransferases and their associated cofactors. Finally, we show that replacement of the Mek1/2 inhibitor with a Src inhibitor preserves the epigenetic and genomic integrity as well as developmental potential of ESCs. Taken together, our data suggest that, while short-term suppression of Mek1/2 in ESCs helps maintain an ICM-like epigenetic state, prolonged suppression results in irreversible changes that compromise their developmental potential.