Glycosylation of KEAP1 links nutrient sensing to redox stress signaling

• Published in: The EMBO journal Vol. 36; no. 15; pp. 2233 - 2250
• Main Authors: Chen, Po‐Han, Smith, Timothy J, Wu, Jianli, Siesser, Priscila F, Bisnett, Brittany J, Khan, Farhan, Hogue, Maxwell, Soderblom, Erik, Tang, Flora, Marks, Jeffrey R, Major, Michael B, Swarts, Benjamin M, Boyce, Michael, Chi, Jen‐Tsan
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.08.2017; Blackwell Publishing Ltd; John Wiley and Sons Inc
• Subjects: Activation; Cell Line; Deprivation; EMBO21; EMBO31; Food; Gene Expression Profiling; Gene Expression Regulation; Glucose; Glycosylation; Humans; KEAP1; Kelch-Like ECH-Associated Protein 1 - metabolism; KLHL; N-Acetylglucosamine; N-Acetylglucosaminyltransferases - metabolism; NF-E2-Related Factor 2 - metabolism; NRF2; Nutrients; O-GlcNAcylation; OGT; Oxidation-Reduction; Post-translation; Proteins; Proteolysis; Serine; Signal Transduction; Stress, Physiological; Stresses; Translation; Ubiquitin; Ubiquitin-protein ligase; Ubiquitination; O‐GlcNAcylation; KEAP1; NRF2; OGT; KLHL
• ISSN: 0261-4189; 1460-2075
• DOI: 10.15252/embj.201696113

O‐GlcNAcylation is an essential, nutrient‐sensitive post‐translational modification, but its biochemical and phenotypic effects remain incompletely understood. To address this question, we investigated the global transcriptional response to perturbations in O‐GlcNAcylation. Unexpectedly, many transcriptional effects of O‐GlcNAc transferase (OGT) inhibition were due to the activation of NRF2, the master regulator of redox stress tolerance. Moreover, we found that a signature of low OGT activity strongly correlates with NRF2 activation in multiple tumor expression datasets. Guided by this information, we identified KEAP1 (also known as KLHL19), the primary negative regulator of NRF2, as a direct substrate of OGT. We show that O‐GlcNAcylation of KEAP1 at serine 104 is required for the efficient ubiquitination and degradation of NRF2. Interestingly, O‐GlcNAc levels and NRF2 activation co‐vary in response to glucose fluctuations, indicating that KEAP1 O‐GlcNAcylation links nutrient sensing to downstream stress resistance. Our results reveal a novel regulatory connection between nutrient‐sensitive glycosylation and NRF2 signaling and provide a blueprint for future approaches to discover functionally important O‐GlcNAcylation events on other KLHL family proteins in various experimental and disease contexts. Synopsis Nutrient‐sensitive post‐translational modification with N‐acetylglucosamine (GlcNAc) is required to restrain the NRF2 antioxidant response in unstressed cells via KEAP1 O‐GlcNAcylation, whose blockage by inhibitors or glucose deprivation stabilizes and activates NRF2 in the absence of stress. Transcriptomics show that O‐GlcNAc transferase (OGT) inhibition activates the NRF2 pathway. O‐GlcNAcylation of the KEAP1 adaptor is required to restrain NRF2 via ubiquitin‐dependent proteolysis. Ser104 O‐GlcNAcylation of KEAP1 promotes its productive interaction with CUL3 ubiquitin ligase. Glucose deprivation reduces KEAP1 O‐GlcNAcylation and activates the NRF2 transcription factor. Graphical Abstract Restraint of the NRF2 antioxidant response in unstressed cells requires O‐GlcNAcylation of the cullin ligase adaptor KEAP1, and can be released by glucose deprivation.