Notch Signaling Reprograms Glial Lipid Metabolism to Promote Hypoxia Resistance

Abstract

Hypoxia poses a major threat to the developing nervous system, where high metabolic demand is required to support brain growth, glial and neuronal maturation, and function. Although glial cells are essential for maintaining neural homeostasis under stress, how specific glial subtypes remodel metabolism to promote hypoxia tolerance remains poorly understood. Here, we identify a Notch-dependent lipid metabolic program in excitatory amino acid transporter 1 (Eaat1)-positive glia that supports hypoxia adaptation in the developing Drosophila larval brain. Using stimulated Raman scattering (SRS) microscopy combined with deuterium-labeled metabolic probes, we visualized substrate-specific metabolic activity in vivo at subcellular resolution. In control, non-adapted flies, we found that acute hypoxia markedly increased de novo lipogenesis in Eaat1-positive glia. In flies adapted to chronic hypoxia, Eaat1-positive glia exhibited a pre-programmed metabolic shift, characterized by reduced glucose-derived lipogenesis and enhanced acetate-derived lipid synthesis. Constitutive activation of Notch signaling in Eaat1-positive glia was sufficient to phenocopy this acetate-favored lipogenic state, suggesting that Notch promotes metabolic plasticity under oxygen-limited conditions. To define the transcriptional programs associated with this response, we performed single-nucleus RNA sequencing (snRNA-seq) of the developing Drosophila central nervous system and mapped Eaat-1expressing cell populations across hypoxia and Notch activation. Notch activation reshaped hypoxia-associated transcriptional responses and counteracted metabolic suppression caused by low oxygen. Together, our findings identify Eaat1-positiveglia as a metabolically adaptive glial population and reveal a conserved Notch-regulated mechanism that rewires lipid metabolism to support hypoxia tolerance in the developing brain. These results provide insight into glial metabolic strategies that may be relevant to hypoxia-associated neurological conditions, including neonatal hypoxic-ischemic brain injury and ischemic stroke.