The role of FUT8‐catalyzed core fucosylation in Alzheimer's amyloid‐β oligomer‐induced activation of human microglia

Abstract Fucosylation, especially core fucosylation of N‐glycans catalyzed by α1‐6 fucosyltransferase (fucosyltransferase 8 or FUT8), plays an important role in regulating the peripheral immune system and inflammation. However, its role in microglial activation is poorly understood. Here we used human induced pluripotent stem cells‐derived microglia (hiMG) as a model to study the role of FUT8‐catalyzed core fucosylation in amyloid‐β oligomer (AβO)‐induced microglial activation, in view of its significant relevance to the pathogenesis of Alzheimer's disease (AD). HiMG responded to AβO and lipopolysaccharides (LPS) with a pattern of pro‐inflammatory activation as well as enhanced core fucosylation and FUT8 expression within 24 h. Furthermore, we found increased FUT8 expression in both human AD brains and microglia isolated from 5xFAD mice, a model of AD‐like cerebral amyloidosis. Inhibition of fucosylation in AβO‐stimulated hiMG reduced the induction of pro‐inflammatory cytokines, suppressed the activation of p38MAPK, and rectified phagocytic deficits. Specific inhibition of FUT8 by siRNA‐mediated knockdown also reduced AβO‐induced pro‐inflammatory cytokines. We further showed that p53 binds to the two consensus binding sites in the Fut8 promoter, and that p53 knockdown abolished FUT8 overexpression in AβO‐activated hiMG. Taken together, our evidence supports that FUT8‐catalyzed core fucosylation is a signaling pathway required for AβO‐induced microglia activation and that FUT8 is a component of the p53 signaling cascade regulating microglial behavior. Because microglia are a key driver of AD pathogenesis, our results suggest that microglial FUT8 could be an anti‐inflammatory therapeutic target for AD.