Oxidative stress induces transient O-GlcNAc elevation and tau dephosphorylation in SH-SY5Y cells.

Emese Kátai,Attila Miseta,Viktor Soma Poór,Rupeena Purewal,József Pál,Tamás Nagy

doi:10.1111/jcmm.12910

Abstract

O‐linked β‐N‐acetlyglucosamine or O‐GlcNAc modification is a dynamic post‐translational modification occurring on the Ser/Thr residues of many intracellular proteins. The chronic imbalance between phosphorylation and O‐GlcNAc on tau protein is considered as one of the main hallmarks of Alzheimer's disease. In recent years, many studies also showed that O‐GlcNAc levels can elevate upon acute stress and suggested that this might facilitate cell survival. However, many consider chronic stress, including oxidative damage as a major risk factor in the development of the disease. In this study, using the neuronal cell line SH‐SY5Y we investigated the dynamic nature of O‐GlcNAc after treatment with 0.5 mM H2O2 for 30 min. to induce oxidative stress. We found that overall O‐GlcNAc quickly increased and reached peak level at around 2 hrs post‐stress, then returned to baseline levels after about 24 hrs. Interestingly, we also found that tau protein phosphorylation at site S262 showed parallel, whereas at S199 and PHF1 sites showed inverse dynamic to O‐Glycosylation. In conclusion, our results show that temporary elevation in O‐GlcNAc modification after H2O2‐induced oxidative stress is detectable in cells of neuronal origin. Furthermore, oxidative stress changes the dynamic balance between O‐GlcNAc and phosphorylation on tau proteins.

Highlights

Cells maintain their intracellular milieu within a quite narrow range
We found that SH-SY5Y cells required about 2–4 hrs to reach peak level of O-GlcNAc following oxidative stress induced by 30 min. treatment with 0.5 mM H2O2
In this study we demonstrated the effect of 30 min. treatment with 0.5 mM H2O2 on the regulation of the O-GlcNAc dynamics in SHSY5Y neuroblastoma cells

Summary

Introduction

Cells maintain their intracellular milieu within a quite narrow range This is a dynamic equilibrium which stabilizes the cells’ internal environment in response to the alterations of external conditions. Stress response induces and regulates a variety of intracellular adaptive mechanisms ranging from receptor binding, signal transduction, gene transcription to protein synthesis [5]. These mechanisms contribute to the survivability of the cells by controlling cell cycle, repairing/stabilizing functional proteins, removing of damaged molecules, mobilizing stored resources and modifying metabolic pathways [3, 6, 7]. Post-translational modifications such as phosphorylation, glycosylation and acetylation play a critical role a 2016 The Authors

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