title: Implications of the O-GlcNAc modification in the regulation of nuclear apoptosis in T cells.
abstract: BACKGROUND
  O-linked β-N-acetylglucosamine (O-GlcNAc) is a nutrient-/stress-sensitive post-translational modification that affects nucleocytoplasmic proteins. The enzyme O-N-acetylglucosamine transferase (OGT) catalyzes the addition of O-GlcNAc, whereas O-N-acetylglucosaminidase (OGA) removes it. O-GlcNAcylation plays a role in fundamental regulatory mechanisms through the modification of proteins involved in cell division, metabolism, transcription, cell signaling and apoptosis. The effects of O-GlcNAcylation on apoptosis appear to be cell-dependent, as elevated levels played a protective role in primary neonatal rat ventricular myocytes but had a cytotoxic effect in rat pancreatic β-cells. The aim of the current study was to determine the implications of the O-GlcNAc modification on T cell apoptosis.
  
  
  METHODS
  Human T lymphoblastic HPB-ALL cells were treated with the OGA inhibitor O-(2-acetamido-2-deoxy-d-glucopyranosylidene) amino-N-phenylcarbamate (PUGNAc), or with glucosamine (GlcN), to increase O-GlcNAcylation. Apoptosis was induced in the presence of tributyltin (TBT). DNA fragmentation was observed by cell cycle analysis and corresponded to the sub G0/G1 population. O-GlcNAcylated proteins were detected by immunoblot using a specific antibody (ctd110.6) and were precipitated using succinylated wheat germ agglutinin (sWGA).
  
  
  RESULTS
  HPB-ALL cells treated with PUGNAc displayed a significant reduction in DNA fragmentation after TBT-induced apoptosis. DFF45, the protein that inhibits the endonuclease DFF40, was identified to be O-GlcNAc modified. O-GlcNAcylated DFF45 appeared to be more resistant to caspase cleavage during apoptosis. Our results suggest that a decrease in the O-GlcNAc modification on DFF45 occurs before its cleavage by caspase.
  
  
  CONCLUSIONS
  Our results indicate that the O-GlcNAcylation of DFF45 may represent a mechanism to control the accidental activation of DFF.
authors.affiliation: INRS-Institut Armand-Frappier, 531 Boul. des Prairies, Laval, QC H7V1B7, Canada.
authors.forename: Bruno
authors.initials: B
authors.lastname: Johnson
authors.forename: Marlyse
authors.initials: M
authors.lastname: Opimba
authors.forename: Jacques
authors.initials: J
authors.lastname: Bernier
mesh_terms: D000117:Acetylglucosamine / Q000031:analogs & derivatives / Q000494:pharmacology; D017209:Apoptosis; D051017:Apoptosis Regulatory Proteins; D015153:Blotting, Western; D002453:Cell Cycle; D002467:Cell Nucleus / Q000378:metabolism / Q000473:pathology*; D015180:Electrophoresis, Gel, Two-Dimensional; D006031:Glycosylation / Q000187:drug effects; D006801:Humans; D047468:Immunoprecipitation; D015459:Leukemia-Lymphoma, Adult T-Cell / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology*; D032383:Myocytes, Cardiac; D017351:N-Acetylglucosaminyltransferases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D010091:Oximes / Q000494:pharmacology; D048448:Phenylcarbamates / Q000494:pharmacology; D011499:Protein Processing, Post-Translational; D011506:Proteins / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D014220:Trialkyltin Compounds / Q000494:pharmacology
chemical_list: D051017:Apoptosis Regulatory Proteins; D010091:Oximes; D048448:Phenylcarbamates; D011506:Proteins; D014220:Trialkyltin Compounds; C109664:caspase-activated DNase inhibitor; C068836:N-acetylglucosaminono-1,5-lactone O-(phenylcarbamoyl)oxime; C011559:tributyltin; D017351:N-Acetylglucosaminyltransferases; D000117:Acetylglucosamine
keywords: Apoptosis; DFF; DFF45; O-(2-acetamidO-2-deoxy-D-glucopyranosylidene) amino-N-phenylcarbamate; O-linked β-N-acetylglucosamine; TBT