| Abstract No.: | B-C2115 |
| Country: | Canada |
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| Title: | HYPO-OSMOLAR STRESS DECREASES GLOBAL PROTEIN O-LINKED O-GLCNACYLATION |
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| Authors/Affiliations: | 1 Reddy Peera Kommaddi*; 1 Philip Barker;
1 Centre for Neuronal Survival, Montreal Neurological Institute, McGill University, QC, Canada
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| Content: | Cells respond to injury or disease by activating various signaling pathways that result in the production or modification of proteins to attenuate stress responses. Several studies have demonstrated that multiple forms of stress rapidly increase global O-linked protein glycosylation and this may protect the cell against injury. O-linked β-N-acetyl-D-glucosamine glycosylation (O-GlcNAcylation) is an important post-translational covalent modification that occurs on nuclear and cytoplasmic proteins. O-GlcNAcylation occurs via addition of single N-acetyl-D-glucosamine moiety to the hydroxyl group of serine or threonine residues through the action of O-GlcNAc transferase (OGT) and can be removed from proteins by β-N-acetyl-D-glucosaminidase (O-GlcNAcase). This reversible modification plays an important role in regulation of gene transcription, translation, protein turnover, and cytoskeletal assembly. The goal of this study was to investigate the effects of extracellular osmolarity on O-GlcNAcylation in primary cortical neurons or HEK293T cells. Here we report that hypo-osmolar stress decreases the global levels of O-GlcNAc in HEK293T cells. Treatment of cells with streptozotocin (STZ) in hypo-osmolar medium induces a moderate expression rescues global levels of O-GlcNAc. We show that hypo-osmolarity decreases the expression of OGT and c-Myc mRNA and increases the expression of p53 mRNA. We propose that hypo-osmolar stress reduces O-GlcNAc by reducing OGT levels and this represents an important element of the in vivo stress response induced by edema during brain injury. |
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