SELENOK-Dependent CD36 Palmitoylation Regulates Microglial Functions and Aß Phagocytosis

Amyloid-beta (Aß) is a key factor in the onset and progression of Alzheimer's disease (AD). Selenium (Se) compounds show promise in AD treatment. Here, we reveal that selenoprotein K (SELENOK), a selenoprotein involved in immune regulation and potentially related to AD pathology, plays a critical role in microglial immune response, migration, and phagocytosis. In vivo and in vitro studies corroborate that SELENOK deficiency inhibits microglial Aß phagocytosis, exacerbating cognitive deficits in 5xFAD mice, which are reversed by SELENOK overexpression. Mechanistically, SELENOK is involved in CD36 palmitoylation through DHHC6, regulating CD36 localization to microglial plasma membranes and thus impacting Aß phagocytosis. CD36 palmitoylation is reduced in the brains of AD patients and mice. Se supplementation promotes SELENOK expression and CD36 palmitoylation, enhancing microglial Aß phagocytosis and mitigating AD progression. We have identified the regulatory mechanisms from Se-dependent selenoproteins to Aß pathology, providing novel insights into potential therapeutic strategies involving Se and selenoproteins. Overall design: Adult microglia mRNA profiles of 10-month-old wild type (WT) and Selk-/- mice