The upregulation of Ulk1-dependent autophagy does not require the p53 activity in mouse embryonic stem cells.

Autophagy is known to play a critical role in the early stages of embryogenesis including the formation of blastocyst. The existence of p53 protein-deficient mice may identify that p53 is not indispensable for the activation of autophagy in pluripotent cells derived from the inner cell mass of the blastocyst. We utilized a p53-knockout (KO) mouse embryonic stem cell (mESC) line to investigate the contribution of p53 in autophagy. We showed that lack of p53 has no effect on cell pluripotency but significantly hinders the differentiation process induced by retinoic acid. Using MRT68921, we revealed that Ulk1-dependent autophagy is activated in response to serum deprivation despite the deletion of p53 in mESCs. However, under retinoic acid-induced differentiation, the accumulation of autophagosomes and lysosomes is impaired in p53 KO mESCs, indicating a critical role of p53 in the regulation of autophagy upon differentiation.