Inhibition of Cell Division and DNA Replication Impair Mouse-Naïve Pluripotency Exit.

The cell cycle has gained attention as a key determinant for cell fate decisions, but the contribution of DNA replication and mitosis in stem cell differentiation has not been extensively studied. To understand if these processes act as "windows of opportunity" for changes in cell identity, we established synchronized cultures of mouse embryonic stem cells as they exit the ground state of pluripotency. We show that initial transcriptional changes in this transition do not require passage through mitosis and that conversion to primed pluripotency is linked to lineage priming in the G1 phase. Importantly, we demonstrate that impairment of DNA replication severely blocks transcriptional switch to primed pluripotency, even in the absence of p53 activity induced by the DNA damage response. Our data suggest an important role for DNA replication during mouse embryonic stem cell differentiation, which could shed light on why pluripotent cells are only receptive to differentiation signals during G1, that is, before the S phase.