Microglial mitochondria transfer to astrocytes via GPNMB-enriched extracellular vesicles alleviates cognitive deficits in tauopathy mice.

Alzheimer's disease (AD) is an irreversible neurodegenerative disease characterized by cognitive decline. The precise molecular mechanisms that underlie the pathogenesis of AD remain elusive. Here we show that glycoprotein nonmetastatic melanoma protein B (GPNMB) is produced by microglia and transferred to astrocytes through extracellular vesicles (EVs) in PS19 tau pathology mice. Tau is cleaved in microglia to generate N-terminal fragments that form a complex on mitochondria with Parkin/Nix and GPNMB, promoting the secretion of EVs containing mitochondria. Functional mitochondria transferred to astrocytes via EVs markedly improve astrocytic functions and attenuate the cognitive impairments and pathogenic features in PS19 mice. By contrast, microglial GPNMB deficiency eliminates mitochondrial EV secretion and mitochondrial transfer to astrocytes, thereby impairing astrocytic functions and exacerbating cognitive impairment in PS19-CcKO (CX3CR1 cre Gpnmb floxp) mice. GPNMB-enriched EVs from PS19 mice alleviate the pathological phenotypes of PS19 mice, offering potential insights for AD treatment.