title: Cross-talk between two essential nutrient-sensitive enzymes: O-GlcNAc transferase (OGT) and AMP-activated protein kinase (AMPK).
abstract: Nutrient-sensitive pathways regulate both O-GlcNAc transferase (OGT) and AMP-activated protein kinase (AMPK), cooperatively connecting metabolic homeostasis to regulation of numerous intracellular processes essential for life. Similar to phosphorylation, catalyzed by kinases such as AMPK, O-GlcNAcylation is a highly dynamic Ser/Thr-specific post-translational modification of nuclear, cytoplasmic, and mitochondrial proteins catalyzed exclusively by OGT. OGT and AMPK target a multitude of intracellular proteins, with the net effect to protect cells from the damaging effects of metabolic stress. Despite hundreds of studies demonstrating significant overlap in upstream and downstream signaling processes, no study has investigated if OGT and AMPK can directly regulate each other. We show acute activation of AMPK alters the substrate selectivity of OGT in several cell lines and nuclear localization of OGT in C2C12 skeletal muscle myotubes. Nuclear localization of OGT affects O-GlcNAcylation of numerous nuclear proteins and acetylation of Lys-9 on histone 3 in myotubes. AMPK phosphorylates Thr-444 on OGT in vitro; phosphorylation of Thr-444 is tightly associated with AMPK activity and nuclear localization of OGT in myotubes, and phospho-mimetic T444E-OGT exhibits altered substrate selectivity. Conversely, the α- and γ-subunits of AMPK are O-GlcNAcylated, O-GlcNAcylation of the γ1-subunit increases with AMPK activity, and acute inhibition of O-GlcNAc cycling disrupts activation of AMPK. We have demonstrated significant cross-talk between the O-GlcNAc and AMPK systems, suggesting OGT and AMPK may cooperatively regulate nutrient-sensitive intracellular processes that mediate cellular metabolism, growth, proliferation, and/or tissue function.
authors.affiliation: Department of Biological Chemistry, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205.
authors.forename: John W
authors.initials: JW
authors.lastname: Bullen
authors.affiliation: Department of Chemistry, University of Virginia, Charlottesville, Virginia 22904.
authors.forename: Jeremy L
authors.initials: JL
authors.lastname: Balsbaugh
authors.affiliation: Department of Molecular Genetics, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, 6200 MD Maastricht, The Netherlands.
authors.forename: Dipanjan
authors.initials: D
authors.lastname: Chanda
authors.affiliation: Department of Chemistry, University of Virginia, Charlottesville, Virginia 22904.
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Shabanowitz
authors.affiliation: Department of Chemistry, University of Virginia, Charlottesville, Virginia 22904; Department of Pathology, University of Virginia, Charlottesville, Virginia 22904.
authors.forename: Donald F
authors.initials: DF
authors.lastname: Hunt
authors.affiliation: Department of Molecular Genetics, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, 6200 MD Maastricht, The Netherlands.
authors.forename: Dietbert
authors.initials: D
authors.lastname: Neumann
authors.affiliation: Department of Biological Chemistry, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205. Electronic address: gwhart@jhmi.edu.
authors.forename: Gerald W
authors.initials: GW
authors.lastname: Hart
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000378:metabolism*; D000117:Acetylglucosamine / Q000378:metabolism; D000818:Animals; D002454:Cell Differentiation; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D049109:Cell Proliferation; D003593:Cytoplasm / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D013058:Mass Spectrometry; D051379:Mice; D018613:Microscopy, Confocal; D018485:Muscle Fibers, Skeletal / Q000378:metabolism; D017351:N-Acetylglucosaminyltransferases / Q000378:metabolism*; D010766:Phosphorylation; D011499:Protein Processing, Post-Translational; D015398:Signal Transduction; D013379:Substrate Specificity
chemical_list: D017351:N-Acetylglucosaminyltransferases; C449880:O-GlcNAc transferase; D055372:AMP-Activated Protein Kinases; D000117:Acetylglucosamine
keywords: AMP-activated Kinase (AMPK); Histones; Nuclear Translocation; Nutrient Sensing; O-GlcNAc; O-GlcNAc Transferase; O-GlcNAcylation; Skeletal Muscle