Chemical Modulation of Glycolysis Regulates the KEAP1-NRF2 Pathway Through a Metabolite-Induced Posttranslational Modification

Glycolysis is a master regulator of cellular energy, synthesis and redox regulation, however the mechanisms that underlie the responses to and regulation of changing glucose metabolism are incompletely understood. The NRF2-antioxidant response element (ARE) pathway serves as a central regulator of cellular stress by sensing and eliminating 2 chemically reactive species in the cell. A phenotypic high-throughput chemical screen for novel activators of NRF2 signaling identified an inhibitor of the glycolytic enzyme PGK1. Metabolomic and proteomic profiling experiments revealed that inhibition of PGK1 results in the accumulation of central glycolytic intermediates, as well as the reactive dicarbonyl metabolite methylglyoxal (MGx). MGx selectively modifies reactive residues on KEAP1, resulting in the formation of a covalent KEAP1 homodimer, accumulation of NRF2 and activation of the NRF2 transcriptional program. Proteomic and NMR experiments verified that KEAP1 homodimerization is mediated by a novel post-translational modification, termed MICA, formed by the reaction of methylglyoxal with proximal cysteine and arginine residues. The identified PGK1 inhibitor series was found to be efficacious in a NRF2-dependent mouse model of UV-damage, demonstrating that activation of KEAP1- NRF2 signaling through this mechanism is physiologically relevant. Together, these results demonstrate the existence of direct inter-pathway communication between glycolysis and the KEAP1-NRF2 transcriptional program, which is mediated by a reactive metaboliteinduced post-translational modification (rmPTM). In addition, they provide new insight into metabolic regulation of cell stress response, and a potential therapeutic axis for controlling the cytoprotective antioxidant response in numerous human diseases. IMR32 cells were treated with 5 µM CBR-470-1 or an equivalent volume of DMSO vehicle control for 24 hours. 3 independent biological replicates per treatment condition were performed for a total of 6 samples.