Aberrant metabolic alterations underlie microglial dysfunction, which plays an important role during neurodegenerative progression. However, the role of aberrant glycogen metabolism remains elusive. Here, we identified glycogen accumulation and upregulated glycogenolytic enzymes in brain microglia from patients with Alzheimer's disease (AD) and transgenic animal models. Particularly, the principal microglial glycogenolytic enzyme PYGL exhibited the most notable spatiotemporal upregulation during disease progression. Specific knockdown of microglial PYGL ameliorated neuropathological changes and cognitive deficits in AD mice. Bioinformatics analysis and experimental validation confirmed that enhancing microglial autophagic flux-dependent Aβ clearance was the underlying mechanism. Furthermore, among all possible glycogenolytic pathways, PYGL downregulation primarily reduced hexosamine biosynthesis pathway activity, diminished UDP-GlcNAc and O-GlcNAcylation of the autophagy key protein SNAP29, and thereby facilitated formation of the SNARE complex, which is essential for autophagosome-lysosome fusion. These findings reveal a glycogenolysis-driven post-translational pathway regulating microglial autophagy, establishing PYGL as a therapeutic target for AD.

Glycogen metabolism  /  Glycogenolysis  /  PYGL  /  O-GlcNAcylation  /  SNARE complex  /  SNAP29  /  Autophagosome–lysosome fusion  /  Autophagy