Swiss Federal Institute of Technology Lausanne, Lausanne, Switzerland
Jesse R Poganik
Swiss Federal Institute of Technology Lausanne, Lausanne, Switzerland; Division of Genetics, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, United States
Swiss Federal Institute of Technology Lausanne, Lausanne, Switzerland; BayRay Innovation Center, Shenzhen Bay Laboratory, Shenzhen, China
Hong-Yu Lin
Department of Chemical Biology, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, China
Xuyu Liu
Swiss Federal Institute of Technology Lausanne, Lausanne, Switzerland; School of Chemistry, The University of Sydney, Sydney, Australia; The Heart Research Institute, Newtown, Newtown, Australia
Marcus John Curtis Long
Department of Biochemistry, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
Studying electrophile signaling is marred by difficulties in parsing changes in pathway flux attributable to on-target, vis-à-vis off-target, modifications. By combining bolus dosing, knockdown, and Z-REX—a tool investigating on-target/on-pathway electrophile signaling, we document that electrophile labeling of one zebrafish-Keap1-paralog (zKeap1b) stimulates Nrf2- driven antioxidant response (AR) signaling (like the human-ortholog). Conversely, zKeap1a is a dominant-negative regulator of electrophile-promoted Nrf2-signaling, and itself is nonpermissive for electrophile-induced Nrf2-upregulation. This behavior is recapitulated in human cells: (1) zKeap1b-expressing cells are permissive for augmented AR-signaling through reduced zKeap1b–Nrf2 binding following whole-cell electrophile treatment; (2) zKeap1a-expressing cells are non-permissive for AR-upregulation, as zKeap1a–Nrf2 binding capacity remains unaltered upon whole-cell electrophile exposure; (3) 1:1 ZKeap1a:zKeap1b-co-expressing cells show no Nrf2-release from the Keap1-complex following whole-cell electrophile administration, rendering these cells unable to upregulate AR. We identified a zKeap1a-specific point-mutation (C273I) responsible for zKeap1a’s behavior during electrophilic stress. Human-Keap1(C273I), of known diminished Nrf2-regulatory capacity, dominantly muted electrophile-induced Nrf2-signaling. These studies highlight divergent and interdependent electrophile signaling behaviors, despite conserved electrophile sensing.
