Hypoxia signaling-driven metabolic reprogramming regulates mouse formative epiblast cell development

Mouse epiblast development is characterized by extensive reprogramming of pluripotent cell states and rapid proliferation. However, the metabolic mechanisms supporting these dynamic processes remain poorly understood. Here we show that hypoxia signaling, marked by nuclear localization of Hif1a, acts as a key regulator of the extensive metabolic reprogramming during the mouse formative epiblast cell development. Using in vivo epiblast samples and a stem-cell-based epiblast development model with naïve mouse embryonic stem cells (mESCs) and formative pluripotent stem cells (fPSCs)-derived 3D rosettes, we reveal that Hif1a-mediated hypoxia signaling suppresses mitochondrial respiration and the glucose metabolism shifts towards the pentose phosphate pathway (PPP) for nucleotide biosynthesis, whereas glutamine (Gln) metabolism is directed towards reductive carboxylation (RC), to supply acetyl-CoA for histone acetylation and lipid synthesis, and amino groups for nucleotide production. These metabolic rewirings collectively sustain both the epigenetic regulation of pluripotent cell fate transitions and the biosynthetic requirements of rapidly proliferating epiblast pluripotent cells. Inhibition of Hif1a signaling compromised all these metabolic rewirings, and the resultant chromatin remodeling and proliferation in fPSCs, with no effects on naïve mESCs. Together, our findings delineate a Hif1a-mediated hypoxia signaling-Gln-RC program that is indispensable for coordinating the anabolic and epigenetic programs to support mouse formative epiblast cell development.