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.

The ketone body β‐hydroxybutyrate shifts microglial metabolism and suppresses amyloid‐β oligomer‐induced inflammation in human microglia

“…We followed a standard procedure to differentiate a human iPS cell line into microglia‐like cells 22 . In a recent article, we confirmed their differentiation and maturation into microglia using specific markers and established the optimal concentration of AβO at 3 μM to activate proinflammatory responses 21 . We tested the effects of BHB in AβO‐stimulated hiMG in low glucose (1.5 mM) medium which would optimally show the metabolic and signaling function of BHB 23 .…”

“…Cells were plated onto Matrigel (Fisher) coated plates and cultured with mTeSR plus (Stemcell Technology). For microglia differentiation, we followed a previously described protocol 21,22 . Briefly, 2 × 10 6 iPSCs were plated onto Aggrewell 800 plates (Stemcell Technology) to form embryoid bodies (EBs) in mTeSR1 supplemented with bone morphogenetic protein 4 (BMP4, 50 ng/mL)/vascular endothelial cell growth factor (VEGF, 50 ng/mL)/stem cell factor (SCF, 20 ng/mL), and culture for four days with daily medium change.…”

“…22 In a recent article, we confirmed their differentiation and maturation into microglia using specific markers and established the optimal concentration of AβO at 3 μM to activate proinflammatory responses. 21 We tested the effects of BHB in AβO-stimulated hiMG in low glucose (1.5 mM) medium which would optimally show the metabolic and signaling function of BHB. 23 (A comparison of the hiMG response in culture with 1.5 and 17.5 mM glucose is shown in Figure S1.)…”

“…For microglia differentiation, we followed a previously described protocol. 21,22 Briefly, 2 × 10 6 iPSCs were plated onto Aggrewell 800 plates (Stemcell Technology) to form embryoid bodies (EBs) in mTeSR1 supplemented with bone morphogenetic protein 4 (BMP4, 50 ng/mL)/vascular endothelial cell growth factor (VEGF, 50 ng/mL)/ stem cell factor (SCF, 20 ng/mL), and culture for four days with daily medium change. On the fifth day, EBs were plated onto gelatin coated 6-well plates with 20 EBs per well in X-VIVO15 (Lonza) supplemented with M-CSF (100 ng/mL), IL-3 (25 ng/mL), glutamax (2 mM), penicillin/streptomycin (100 U/mL and 100 ug/mL), and β-mercaptoethanol (55uM), and the medium was changed weekly.…”

Targeting protein glycosylation to regulate inflammation in the respiratory tract: novel diagnostic and therapeutic candidates for chronic respiratory diseases

“…In vitro studies have demonstrated that inhibiting or genetically depleting FUT2 ( 228 ) and FUT4 ( 114 ) can be effective therapies for these cancers. FUT8, a key regulator of the p53 signaling cascade, is a promising therapeutic target for cancer and inflammatory diseases, including Alzheimer’s disease (AD) ( 229 ). FUT8 and core fucosylation inhibition are prospective therapeutic strategies for cancer and inflammation.…”