Dexmedetomidine Inhibits NF-κB-Transcriptional Activity in Neurons Undergoing Ischemia-Reperfusion by Regulating O-GlcNAcylation of SNW1

Dexmedetomidine (Dex) is neuroprotective in ischemia-reperfusion (I/R) by suppressing inflammation but the underlying molecular mechanisms are not known. SNW domain-containing protein 1 (SNW1) is a coactivator of the pro-inflammatory transcription factor NF-κB p65. Because SNW1 is regulated by O-GlcNAcylation, we aimed to determine whether this modification influences NF-κB transcriptional activity in neurons undergoing I/R and how Dex may affect the O-GlcNAcylation of SNW1. SH-SY5Y and PC12 cells under hypoxia/reoxygenation (H/R) conditions were treated with Dex and with inhibitors of O-GlcNAc transferase (OGT). O-GlcNAc levels in SNW1 and effects of SNW1 on NF-κB p65 were determined by immunoprecipitation. H/R increased SNW1 protein levels but inhibited O-GlcNAcylation of SNW1. A Luciferase reporter assay demonstrated that increased SNW1 levels led to increased NF-κB p65 activity and increased secretion of neuron-derived inflammatory factors demonstrated by ELISA. Dex reversed the H/R-induced increase of SNW1 protein by upregulating OGT and enhancing O-GlcNAcylation of SNW1. Dex suppression of the SNW1/NF-κB complex resulted in neuroprotection in vitro and in a middle cerebral artery occlusion model in vivo. PKA and ERK1/2 inhibitors abolished the effect of Dex on OGT protein. Taken together, these data indicate that Dex inhibits NF-κB-transcriptional activity in neurons undergoing I/R by regulating O-GlcNAcylation of SNW1.