TCA cycle rewiring underpins histone acetylation sourcing and cell-fate transitions during exit from naive pluripotency.

Metabolism shapes stem cell differentiation and epigenome regulation, especially during the exit from naive pluripotency in vitro. Yet how metabolic networks reorganize at implantation remains unclear. Here, we map metabolite routing in pre- and post-implantation mouse embryos and across dynamic pluripotency transitions in stem cells, revealing that the tricarboxylic acid (TCA) cycle undergoes spatio-temporal rewiring rather than a simple shutdown. Pyruvate emerges as a central metabolic nexus, where pyruvate carboxylase and malic enzyme activities create a cyclical carbon flow essential for balanced metabolic and transcriptional states, timely exit from naive pluripotency, and differentiation. As cells leave naive pluripotency, glutamine increasingly fuels the TCA cycle; unexpectedly, it is also the dominant carbon source for histone acetylation. The necessary acetyl-CoA is generated via IDH1-mediated reductive glutamine carboxylation and is coupled to pyruvate cycling, sustaining histone acetylation. These findings uncover a metabolically rewired, route-specific nutrient utilization program that links metabolism to epigenomic regulation and pluripotency transitions at implantation.