Molecular and functional features of synucleinopathy-associated astrocytes

Astrocyte (AC) involvement is a common neuropathological feature in human synucleinopathy-associated neurodegeneration. However, our understanding of the in vivo characteristics of reactive ACs in synucleinopathy remained limited. Here we report the transcriptomic and functional features of a unique synucleinopathy-associated AC (SAA) subtype in a mouse model. SAAs share a convergent transcriptomic state across synucleinopathy-laden brain regions, and are at least partially reliant on microglia for their phenotypic maintenance in vivo. Intravital imaging revealed that an upregulation of the excitatory amino acid transporter 2 (EAAT2) in synucleinopathy-affected ACs is associated with depressed neuronal activities. This is potentially mediated via increased AC glutamate uptake, as pharmacological induction of EAAT2 reproduced the same effect. With cross-species comparative analysis, we showed that the core SAA transcriptomic features are present in human aged and synucleinopathy-affected midbrain ACs, while important distinct characteristics also exist. Collectively, our results uncovered complex reactive AC changes that likely play important adaptive roles in synucleinopathy. Overall design: Mouse brain frontal cortex and midbran two regions from Hua-Syn(A53T) and wildtype mice group(3 mice each group) were acquired to perform scRNAseq.