Cell cycle-balanced expression of pluripotency regulators via cyclin-dependent kinase 1

Embryonic stem cells (ESCs) have a unique ability to remain pluripotent while undergoing rapid rounds of cell division required for self-renewal. However, it is not known how cell cycle and pluripotency regulatory networks co-operate in ESCs. Here, we used stable isotope labeling with amino acids in cell culture (SILAC) combined with mass spectrometry to determine pluripotency proteome dynamics during cell cycle in mouse ESCs. We found the S/G2M-fluctuating pluripotency transcription factors (ESRRB, REST), chromatin regulators (JARID2, TRIM24) and proteins with E3 ligase activity (NEDD4L, PIAS2) to peak in S phase. This expression balance was disrupted upon inhibition of cyclin-dependent kinase 1 (CDK1) activity resulting in the shift of the expression peak from S to G2M. Our results demonstrate that mouse ESCs require CDK1 activity to maintain high S to G2M ratio of pluripotency regulators revealing critical role of cell cycle dynamics in balancing ESC identity.