Creatine metabolism regulates trophectoderm formation in early mouse embryos via an energy-cytoskeleton-YAP axis

Creatine metabolism plays a well-established role in somatic cell energy homeostasis, but its function and mechanisms during early mammalian embryonic development remain unclear. Our findings reveal that creatine metabolism is critical for mouse embryo development from the 8-cell to the blastocyst stage. Inhibition of creatine metabolism causes stage-specific arrest at the morula-to-blastocyst transition, significantly impairing trophectoderm (TE) formation in blastocysts, and has no significant effect on the inner cell mass (ICM). Mechanistically, disruption of creatine metabolism leads to decreased ATP levels, which not only disturbs actin-related protein 2 (ARP2) distribution and inhibits ARP2-mediated assembly of F-actin but also activates AMPK. Together, these effects hinder the nuclear localization of the Hippo pathway effector Yes-associated protein (YAP). Impaired YAP nuclear translocation results in the downregulation of genes related to TE formation, actin cytoskeleton, and creatine metabolism. Exogenous supplementation with creatine, YAP agonists, or AMPK inhibitors can partially reverse the aforementioned abnormalities. This study uncovers that creatine metabolism regulates TE formation during early embryonic development through a central axis of "energy buffering-F-actin assembly-YAP activation," providing new insights into the metabolic regulation of preimplantation development in mammals.