Intracellular α-ketoglutarate maintains the pluripotency of embryonic stem cells

The role of cellular metabolism in regulating cell proliferation and differentiation remains poorly understood(1). For example, most mammalian cells cannot proliferate without exogenous glutamine supplementation even though glutamine is a non-essential amino acid(1,2). Here we show that mouse embryonic stem (ES) cells grown under conditions that maintain naive pluripotency(3) are capable of proliferation in the absence of exogenous glutamine. Despite this, ES cells consume high levels of exogenous glutamine when the metabolite is available. In comparison to more differentiated cells, naive ES cells utilize both glucose and glutamine catabolism to maintain a high level of intracellular alpha-ketoglutarate (alpha KG). Consequently, naive ES cells exhibit an elevated alpha KG to succinate ratio that promotes histone/DNA demethylation and maintains pluripotency. Direct manipulation of the intracellular alpha KG/succinate ratio is sufficient to regulate multiple chromatin modifications, including H3K27me3 and ten-eleven translocation (Tet)-dependent DNA demethylation, which contribute to the regulation of pluripotency-associated gene expression. In vitro, supplementation with cell-permeable alpha KG directly supports ES-cell self-renewal while cell-permeable succinate promotes differentiation. This work reveals that intracellular alpha KG/succinate levels can contribute to the maintenance of cellular identity and have a mechanistic role in the transcriptional and epigenetic state of stem cells.