Genetic dissection of one-carbon metabolism: Roles in pluripotency and embryonic development.

One-carbon (1C) metabolism is a central metabolic network that integrates nutrient availability with biosynthetic and epigenetic processes essential for embryonic and placental development. By transferring carbon units derived from amino acids and folate metabolism, this pathway generates nucleotides, methyl donors, and other intermediates required for cell proliferation and differentiation. The pathway is compartmentalized between mitochondria and cytosol, with mitochondrial reactions frequently supplying formate and other 1C units to sustain cytosolic biosynthesis in rapidly dividing cells. Pluripotent stem cells illustrate the strong dependence of cell identity on 1C metabolism. Mouse embryonic stem cells rely on threonine catabolism to produce glycine, acetyl-CoA, and S-adenosylmethionine (SAM), which supports chromatin methylation and self-renewal. In contrast, human ESCs lack a functional threonine catabolic pathway and instead depend on high methionine metabolism and glycine cleavage to maintain SAM levels and pluripotency. Genetic and metabolomic studies in diverse animal models have revealed stage-specific roles for 1C metabolism in processes including zygotic genome activation, DNA replication, epigenetic reprogramming, cell-cycle progression, organogenesis, cell migration, and longevity. Importantly, disruption of individual enzymes often produces defined developmental defects rather than general metabolic failure. Beyond early development, 1C metabolism also contributes to transgenerational epigenetic inheritance through its effects on germline DNA and histone methylation which are sensitive to perturbations in the folate and methionine pathways. Together, these findings show that 1C-metabolism links cellular metabolism with epigenetic regulation and developmental processes.