The role of N-Glycan modification of TNFR1 in inflammatory microglia activation

Abstract

Accumulating evidences demonstrated that microglia activation and the autocrine loop of tumor necrosis factor-α (TNFα) greatly contribute to the pathogenesis of several CNS diseases. TNFα exerts its biological effects by interacting with two different receptors: TNF receptor 1 (TNFR1) and TNFR2. The classic proinflammatory activity of TNFα is mainly mediated by TNFR1. In the present study, we found that TNFR1 was modificated by N-glycosylation on Asn151 and Asn202 in microglia. The N-glycosylation of TNFR1 could facilitate its capability of binding to TNFα and further promote the formation of TNFα autocrine loop in microglia stimulated by TNFα, resulting in excessive microglia activation and CNS inflammation. All these processes were related to TNFR1-mediated NF-κB pathways. Elimination of N-glycosylation did not affect the subcellular transportation and cell surface localization of TNFR1, but suppressed ligand-binding affinity. These findings indicated that the N-glycosylation of TNFR1 played an important role during microglia activation in CNS inflammation. By this study, we aimed to provide some valuable experimental evidence for a better understanding of the significance of protein glycosylation in microglia inflammatory activation and CNS disease.

Lys63/Met1-hybrid ubiquitin chains are commonly formed during the activation of innate immune signalling

“…Treatment of the Halo-NEMO beads with USP2 converted these high molecular mass forms to much faster migrating species, indicating that TNFα had triggered the ubiquitylation of TNFR1. The electrophoretic mobility of TNFR1 was increased further by incubation of the Halo-NEMO beads with USP2 plus the PNGase F, which hydrolyses carbohydrate moieties attached to asparagine residues on TNFR1 [31] . PNGase F and phageλ protein phosphatase (λPPase) were therefore included in all subsequent experiments to remove covalently bound carbohydrate and phosphate from TNFR1, which might otherwise complicate interpretation of the results.…”

Glycosylation as a Main Regulator of Growth and Death Factor Receptors Signaling

“…TNFRSF1A and TNFRSF1B contain 3 and 2 N -glycosylation sites, respectively. Inhibition of N -glycosylation of TNFRSF1A in microglial cells results in inhibition of ligand binding [ 20 ]. In macrophages, α2,6-sialylation of TNFRSF1A protects from apoptosis [ 49 ].…”

Neurodegenerative Susceptibility During Maternal Nutritional Programing: Are Central and Peripheral Innate Immune Training Relevant?

“…Also, ALS patients and mouse models of the disease have elevated levels of TNFα, IL-6, and IL-1β in blood and cerebrospinal fluid. In addition to TNF-α upregulation in ALS, TNFR1, and TNFR2 transcripts have also been found to be overexpressed in ALS patients compared with non-neurological controls (Han et al, 2015;Tortarolo et al, 2017). Similar to Alzheimer, Parkinson and Huntington, modulation of inflammatory cytokine-dependent pathways prevent neuronal death in ALS models.…”