Dynamic O-GlcNAc Modification of Nucleocytoplasmic Proteins in Response to Stress

Abstract

Cellular response to environmental, physiological, or chemical stress is key to survival following injury or disease. Here we describe a unique signaling mechanism by which cells detect and respond to stress in order to survive. A wide variety of stress stimuli rapidly increase nucleocytoplasmic protein modification by O-linked β-N-acetylglucosamine (O-GlcNAc), an essential post-translational modification of Ser and Thr residues of metazoans. Blocking this post-translational modification, or reducing it, renders cells more sensitive to stress and results in decreased cell survival; and increasing O-GlcNAc levels protects cells. O-GlcNAc regulates both the rates and extent of the stress-induced induction of heat shock proteins, providing a molecular basis for these findings. Cellular response to environmental, physiological, or chemical stress is key to survival following injury or disease. Here we describe a unique signaling mechanism by which cells detect and respond to stress in order to survive. A wide variety of stress stimuli rapidly increase nucleocytoplasmic protein modification by O-linked β-N-acetylglucosamine (O-GlcNAc), an essential post-translational modification of Ser and Thr residues of metazoans. Blocking this post-translational modification, or reducing it, renders cells more sensitive to stress and results in decreased cell survival; and increasing O-GlcNAc levels protects cells. O-GlcNAc regulates both the rates and extent of the stress-induced induction of heat shock proteins, providing a molecular basis for these findings. Key metabolic proteins in the nucleus and cytoplasm of metazoans are dynamically modified by monosaccharides of O-linked β-N-acetylglucosamine (O-GlcNAc) 1The abbreviations used are: O-GlcNAc, monosaccharides of O-linked β-N-acetylglucosamine; CHO, Chinese hamster ovary; Me2SO, dimethyl sulfoxide; DON, 6-diazo-5-oxonorleucine; HEK293, human embryonic kidney 293; FBS, fetal bovine serum; HCAEC, human coronary artery endothelial cells; HSF1, heat shock factor 1; HSP, heat shock protein; Neuro-2A, neuroblastoma 2A cells; MEFs, mouse embryonic fibroblasts; O-GlcNAcase, O-GlcNAc hexosaminidase (EC 3.2.1.52); OGT, UDP-GlcNAc, polypeptide O-β-N-acetylglucosaminyltransferase (EC 2.4.1.94); PBS, phosphate-buffered saline; PUGNAc, O-(2-acetamido-2-deoxy-d-glucopyranosylidene) amino-N-phenylcarbamate; RNAi, RNA interference; DMEM, Dulbecco's modified Eagle's medium; HSP, heat shock protein; OGT, O-β-N-acetylglucosaminyltransferase; ALLN, N-acetyl-l-leucyl-l-leucyl-l-norleucinal. (1Wells L. 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Exp. 1997; PubMed Scopus Google Scholar). for in rates modulating O-GlcNAc is as a of cells. a of and are at are the of a RNA cells at in in and to and cells to the and at the OGT an of and the to the The used are as and of S. The cells at in in and and the to of DNA or to the and O-GlcNAc in to of Cellular the of the O-GlcNAc protein modification in stress response levels of O-GlcNAc cells to different of cellular in response to levels of O-GlcNAc A and as heat shock and data in cells and The of OGT, the enzyme that the addition of O-GlcNAc to the protein of levels of OGT protein Notably, O-GlcNAc protein modification in response to stress is O-GlcNAc protein modification of nucleocytoplasmic proteins is cells as for of O-GlcNAc and in cell in by of O-GlcNAc to is shown in the cells as and at for of O-GlcNAc and in cell in by of O-GlcNAc to is shown in the cells heat shock for for at or or for of O-GlcNAc and in cell in by of O-GlcNAc to is shown in the cells heat shock at for for or or for of O-GlcNAc and in cell in by of O-GlcNAc to is shown in the are the of a O-GlcNAc protein modification by cellular stress is a O-GlcNAc in response to and stress in different cell including MEFs, and These data suggest that O-GlcNAc is a and of stress response O-GlcNAc and in to O-GlcNAc to proteins in a dynamic a in the of addition of O-GlcNAc in response to O-GlcNAc levels at the of stress that O-GlcNAc addition is rapidly the of addition is as levels of O-GlcNAc to increase for are by and to by Notably, O-GlcNAc induction to of protein levels OGT levels to The of O-GlcNAc in response to to the data and the that protein and are The is protein at in cells. 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