title: O-Linked β-N-acetylglucosamine (O-GlcNAc) Acts as a Glucose Sensor to Epigenetically Regulate the Insulin Gene in Pancreatic Beta Cells.
abstract: The post-translational protein modification O-linked β-N-acetylglucosamine (O-GlcNAc) is a proposed nutrient sensor that has been shown to regulate multiple biological pathways. This dynamic and inducible enzymatic modification to intracellular proteins utilizes the end product of the nutrient sensing hexosamine biosynthetic pathway, UDP-GlcNAc, as its substrate donor. Type II diabetic patients have elevated O-GlcNAc-modified proteins within pancreatic beta cells due to chronic hyperglycemia-induced glucose overload, but a molecular role for O-GlcNAc within beta cells remains unclear. Using directed pharmacological approaches in the mouse insulinoma-6 (Min6) cell line, we demonstrate that elevating nuclear O-GlcNAc increases intracellular insulin levels and preserves glucose-stimulated insulin secretion during chronic hyperglycemia. The molecular mechanism for these observed changes appears to be, at least in part, due to elevated O-GlcNAc-dependent increases in Ins1 and Ins2 mRNA levels via elevations in histone H3 transcriptional activation marks. Furthermore, RNA deep sequencing reveals that this mechanism of altered gene transcription is restricted and that the majority of genes regulated by elevated O-GlcNAc levels are similarly regulated by a shift from euglycemic to hyperglycemic conditions. These findings implicate the O-GlcNAc modification as a potential mechanism for hyperglycemic-regulated gene expression in the beta cell.
authors.affiliation: From the Complex Carbohydrate Research Center, Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia 30602-1516 and.
authors.forename: Sean P
authors.initials: SP
authors.lastname: Durning
authors.affiliation: From the Complex Carbohydrate Research Center, Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia 30602-1516 and.
authors.forename: Heather
authors.initials: H
authors.lastname: Flanagan-Steet
authors.affiliation: HudsonAlpha Institute of Biotechnology, Genomic Services Laboratory, Huntsville, Alabama 35806.
authors.forename: Nripesh
authors.initials: N
authors.lastname: Prasad
authors.affiliation: From the Complex Carbohydrate Research Center, Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia 30602-1516 and lwells@ccrc.uga.edu.
authors.forename: Lance
authors.initials: L
authors.lastname: Wells
mesh_terms: D000117:Acetylglucosamine / Q000737:chemistry*; D000818:Animals; D002460:Cell Line; D019295:Computational Biology; D044127:Epigenesis, Genetic; D005786:Gene Expression Regulation; D016678:Genome; D005947:Glucose / Q000378:metabolism*; D059014:High-Throughput Nucleotide Sequencing; D007328:Insulin / Q000235:genetics* / Q000378:metabolism*; D050417:Insulin-Secreting Cells / Q000378:metabolism*; D007340:Insulinoma / Q000378:metabolism; D051379:Mice; D018613:Microscopy, Confocal; D011499:Protein Processing, Post-Translational; D012333:RNA, Messenger / Q000378:metabolism
chemical_list: D007328:Insulin; D012333:RNA, Messenger; D005947:Glucose; D000117:Acetylglucosamine
keywords: O-linked N-acetylglucosamine (O-GlcNAc); RNASeq; beta cell (B-cell); diabetes; epigenetics; insulin; post-translational modification (PTM)