Succinylation of a KEAP1 sensor lysine promotes NRF2 activation

Abstract

Crosstalk between metabolism and stress-responsive signaling is essential to maintaining cellular homeostasis. One way this crosstalk is achieved is through the covalent modification of proteins by endogenous, reactive metabolites that regulate the activity of key stress-responsive transcription factors such as NRF2. Several metabolites including methylglyoxal, glyceraldehyde 3-phosphate, fumarate, and itaconate covalently modify sensor cysteines of the NRF2 regulatory protein KEAP1, resulting in stabilization of NRF2 and activation of its cytoprotective transcriptional program. Here, we employed a shRNA-based screen targeting the enzymes of central carbon metabolism to identify additional regulatory nodes bridging metabolic pathways to NRF2 activation. We found that succinic anhydride, increased by genetic depletion of the TCA cycle enzyme succinyl-CoA synthetase or by direct administration, results in N-succinylation of lysine 131 of KEAP1 to activate NRF2 transcriptional signaling. This study identifies KEAP1 as capable of sensing reactive metabolites not only by several cysteine residues but also by a conserved lysine residue, indicating its potential to sense an expanded repertoire of reactive metabolic messengers.

The Glycolytic Metabolite Methylglyoxal Covalently Inactivates the NLRP3 Inflammasome

“…KEAP1 bears 12 sensor cysteines which respond to covalent modification by liberating NRF2 sufficiently to enact a protective transcriptional response 20 . In addition to exogenous electrophilic chemicals, KEAP1 has been shown to covalently sense endogenous reactive electrophilic metabolites induced by perturbations in the TCA cycle and glycolysis, resulting in NRF2 activation 21,22 . Both the TCA cycle metabolite fumarate and the TCA cycle derived metabolite itaconate are established activators of NRF2 that covalently modify sensor cysteines in the BTB domain of KEAP1 23-27 .…”