CLU alleviates Alzheimer’s disease-relevant processes by modulating astrocyte reactivity and microglia-dependent synaptic density [scRNA-seq]

Genetic studies implicate Clusterin (CLU) in the pathogenesis of Alzheimer’s disease (AD), yet its precise molecular impact remains unclear. Through unbiased proteomic profiling and functional validation in CLU-deficient astrocytes, we identify increased NfkB-dependent signaling and complement C3 secretion. Reduction of astrocyte CLU induced microglia dependent modulation of extracellular APOE and phosphorylated tau, as well as increased microglial phagocytosis and reduced synapse numbers. By integrating mouse and human cellular models with comprehensive analyses of human plasma and brain tissue, we demonstrate that CLU AD risk alleles are associated with reduced CLU protein and heightened inflammatory profiles. These findings establish a mechanistic link between AD genetic risk factors, astrocyte reactivity, and microglia-mediated effects on synaptic integrity. Collectively, these results support a model in which CLU upregulation in response to neuropathology is associated with maintenance of cognitive function, while diminished astrocyte CLU levels heighten disease susceptibility. iNs and iAs (CLU WT or CLU KO) were differentiated to day 20 and iMGs were differentiated to day 40. On day 20, iAs were dissociated and replated on top of iN cultures. On day 21 (day 40 of iMG differentiation), iMGs were dissociated and replated on top of iN-iA co-cultures. All three cell types were then co-cultured together for an additional six days, after which they were dissociated and analyzed by single-cell RNA-sequencing.