title: Aβ-affected pathogenic induction of S-nitrosylation of OGT and identification of Cys-NO linkage triplet.
abstract: Mechanistic link of protein hypo-O-GlcNAcylation to the pathogenesis of Alzheimer's disease (AD) remains unclear. Here, we found that S-nitrosylation of O-linked N-acetylglucosaminyltransferase (SNO-OGT) was induced by β-amyloid peptide (Aβ) exposure to SK-N-MC and SK-N-SH human neuroblastoma cells. Subsequently, Aβ-induced SNO-OGT led to protein hypo-O-GlcNAcylation globally including tau hypo-O-GlcNAcylation. Our results support that underlying mechanism for induction of SNO-OGT comprises the concerted action of Aβ-triggered Ca2+ entry into cells and nNOS-catalyzed NO production. Intriguingly, OGT was found to be associated with nNOS and its association was enhanced during Aβ treatment. In parallel with SNO-OGT-mediated tau hypo-O-GlcNAcylation, Aβ led to SNO-Akt-mediated GSK3β activation for tau phosphorylation, suggesting that tau hyperphosphorylation is established by synergistic connection between SNO-OGT and GSK3β activation. We also observed that Aβ-neurotoxicity including both reactive oxygen species (ROS) production and cell death was amplified with DON treatment, whereas it was restored by PUGNAc treatment, GlcNH2 treatment or OGT overexpression. Early time-course Aβ-monitoring assay revealed that premaintained hyper-O-GlcNAcylation inside cells blocked not only Aβ-triggered Ca2+ entry into cells but also induction of SNO-OGT and SNO-Akt. Together, these findings suggest that induction of SNO-OGT by Aβ exposure is a pathogenic mechanism to cause cellular hypo-O-GlcNAcylation by which Aβ neurotoxicity is executed, and conversely, hyper-O-GlcNAcylation within cells can defend against Aβ neurotoxicity. Furthermore, our Cys mapping demonstrates that cysteine-nitric oxide (Cys-NO) linkages in SNO-OGT occur at triple Cys845, Cys921, and Cys965 residues in C-terminal catalytic domain (C-CAT), suggesting that Cys-NO linkage triplet in SNO-OGT is associated with null OGT activity.
authors: Department of Life Science, Ajou University, Suwon City, Republic of Korea.
authors: In-Hyun
authors: IH
authors: Ryu
authors: GG Pharmaceutical Institute, Seoul, Republic of Korea.
authors: Ki-Young
authors: KY
authors: Lee
authors: Department of Life Science, Ajou University, Suwon City, Republic of Korea. Electronic address: sido@ajou.ac.kr.
authors: Su-Il
authors: SI
authors: Do
mesh_terms: D000215:Acylation; D000544:Alzheimer Disease / Q000378:metabolism* / Q000473:pathology; D016229:Amyloid beta-Peptides / Q000737:chemistry / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D003545:Cysteine / Q000737:chemistry; D038362:Glycogen Synthase Kinase 3 / Q000737:chemistry / Q000378:metabolism; D000071679:Glycogen Synthase Kinase 3 beta; D006801:Humans; D017351:N-Acetylglucosaminyltransferases / Q000737:chemistry* / Q000378:metabolism; D009569:Nitric Oxide / Q000737:chemistry; D010766:Phosphorylation; D011499:Protein Processing, Post-Translational / Q000235:genetics*; D017382:Reactive Oxygen Species; D015398:Signal Transduction / Q000235:genetics
chemical_list: D016229:Amyloid beta-Peptides; D017382:Reactive Oxygen Species; D009569:Nitric Oxide; D017351:N-Acetylglucosaminyltransferases; C063057:UDP-N-acetylglucosamine-peptide beta-N-acetylglucosaminyltransferase; C000605506:GSK3B protein, human; D000071679:Glycogen Synthase Kinase 3 beta; D038362:Glycogen Synthase Kinase 3; D003545:Cysteine; D002118:Calcium
keywords: Aβ neurotoxicity; Cys-NO linkages; Hypo-O-GlcNAcylation; O-GlcNAc; OGT; SNO-OGT