Nuclear compression-mediated DNA damage drives ATR-dependent Lamin expression and mouse ESC differentiation.

Embryonic stem cells (ESCs), which are susceptible to DNA damage, depend on a robust and highly efficient DNA damage response (DDR) mechanism for their survival. However, the implications of physical force-mediated DNA damage on ESC fate remain unclear. We show that stiffness-dependent spreading of mouse ESCs (mESCs) induces DNA damage through nuclear compression, with DNA damage causing differentiation through Lamin A/C. Interestingly, differentiation is associated with DNA damage and activation of the DDR factors such as ATR and CHK1. While ATR is typically known to play roles in DDR pathway, its role during stiffness-mediated nuclear compression and mESC differentiation is unknown. While our results show activation of CHK1 pathway and nuclear enrichment of activated ATR on stiff substrates, inhibiting ATR and CHK1 both result in reduction of Lamin A/C expression by different mechanisms. Overall, we demonstrate that mESC differentiation is driven by nuclear compression-mediated DNA damage and involves ATR-dependent modulation of Lamin A/C.