DAP12 deficiency alters microglia-oligodendrocyte communication and enhances resilience against tau toxicity

Pathogenic tau accumulation fuels neurodegeneration in Alzheimer's disease (AD). The role of microglia in tau-driven neurodegeneration is intricate, with DAP12 (DNAX-activation protein 12) triggering microglial immune responses. Mice lacking DAP12 become resistant to tau-induced brain toxicity in tauopathy mice, yet the precise mechanism remains elusive. Our current study uncovers a novel resilience mechanism against tau toxicity conferred by Dap12 deletion. While inactivation of Dap12 elevates tau inclusions, potentially disrupting microglial tau processing, it curbs tau-induced brain inflammation and ameliorates myelin and synapse loss. Tau-induced disease-associated clusters in microglia (MG) and intermediate oligodendrocytes (iOli) are abolished by removal of Dap12. Additionally, AD brains exhibit mouse iOli-like cells spatially correlated with tau pathology. In summary, our study reveals that DAP12 signaling triggers toxic interactions between microglia and oligodendrocytes in tauopathy, mediating tau-induced damage to oligodendrocytes and synaptic loss. Targeting DAP12 signaling presents a promising therapeutic approach for enhancing resilience against tau toxicity in AD. Overall design: Droplet-based single nuclear RNA sequencing of mouse hippocampus of WT, Dap12+/+ tau+ and Dap12–/–tau+.