Comprehensive Profiling of Aβ40 and Aβ42 Fibril-Interacting Proteins Reveals PRKCG as a Drug-Targetable Regulator of Amyloidogenesis in Alzheimer’s Disease

Proteins associated with amyloid-β (Aβ) pathology are critical biomarkers and potential therapeutic targets for Alzheimer’s disease (AD). Previous studies analyzing Aβ plaque composition relied on micro-dissected plaques from tissue samples. Here, we aimed to study the proteome associated with Aβ40- and Aβ42-plaques to identify protein constituents of Aβ plaques—actual Aβ40- and Aβ42-fibril interactors—, which might drive Aβ plaque development. Biotinylated-Aβ40, or -Aβ42, were incubated to form fibrils, with scrambled peptides used as control, and subjected to pull-down assays using protein extracts from AD and control prefrontal cortex tissues. Aβ-interacting proteins were identified by proteomics. Their dysregulation was assessed in AD tissue samples and a cellular AD model by WB, immunocytochemistry, in silico, and immunohistochemistry. We identified 185 and 874 proteins associated with Aβ40- and Aβ42-fibrils, respectively, with 78 in common. Sixteen were validated as interactors by WB and ex vivo as components of Aβ plaques by IF, displaying altered expression in AD and supporting a functional role for PRKCG in amyloidogenesis, as its modulation alters Aβ fibril formation. This study expands the Aβ plaque-associated proteome characterization, identifies novel fibril interactors, and highlight potential therapeutic targets, as the modulation of PRKCG prevent or reduce Aβ plaque formation in AD.