Implications of the O-GlcNAc modification in the regulation of nuclear apoptosis in T cells.

Bruno Johnson (1) , Marlyse Opimba (1) , Jacques Bernier (1)

1 INRS-IAF - Institut Armand Frappier

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. GENERAL SIGNIFICANCE: Our results indicate that the O-GlcNAcylation of DFF45 may represent a mechanism to control the accidental activation of DFF.

Mots clés: DFF45; Apoptosis; TBT; DFF; O-linked β-N-acetylglucosamine; TBT; DFF45; O-(2-acetamidO-2-deoxy-D-glucopyranosylidene) amino-N-phenylcarbamate; DFF; O-linked β-N-acetylglucosamine; O-(2-acetamidO-2-deoxy-D-glucopyranosylidene) amino-N-phenylcarbamate

Domaines: Toxicologie; Chimie

Bruno Johnson, Marlyse Opimba, Jacques Bernier. Implications of the O-GlcNAc modification in the regulation of nuclear apoptosis in T cells.. BBA - Biochimica et Biophysica Acta, 2014, 1840 (1), pp.191-8. ⟨10.1016/j.bbagen.2013.09.011⟩. ⟨hal-01177334⟩