Autophagy regulator ATG5 preserves cerebellar function by safeguarding its glycolytic activity

Dysfunctions in autophagy, a highly conserved cellular mechanism responsible for the degradation of intracellular components within lysosomes, often result in neurodegeneration. The neuroprotective effect of autophagy varies across neuronal subtypes, and the mechanisms of selective vulnerability of neurons to autophagy dysfunction are currently unknown. Utilizing a mouse model of ATG5 deficiency in inhibitory neurons and a comprehensive approach, including PET imaging, metabolomics, stable-isotope labeling studies, and live cell imaging, we establish that autophagy contributes to the survival of cerebellar Purkinje cells (PCs) by safeguarding their glycolytic activity. We show that the core autophagy protein ATG5 downregulates the levels of the glucose transporter 2 (GLUT2) during brain maturation. Autophagy-deficient PCs exhibit increased glucose uptake along with elevated levels of glycolytic intermediates and methylglyoxal-modified proteins. We propose lysophosphatidic acid and serine as glycolytic intermediates inducing PC death and demonstrate that deletion of GLUT2 in ATG5-deficient mice mitigates PC neurodegeneration and restores their ataxic gait. Taken together, this study reveals a novel neuroprotective role of autophagy in preventing excessive glycolytic metabolism in the brain.