Z-REX uncovers a bifurcation in function of Keap1 paralogs

Van Hall-Beauvais, A.; Poganik, J. R.; Huang, K.-T.; Parvez, S.; Zhao, Y.; Lin, H.-Y.; Liu, X.; Long, M. J. C.; Aye, Y.

doi:10.1101/2022.10.10.511579

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bioRxiv · 10.1101/2022.10.10.511579

Z-REX uncovers a bifurcation in function of Keap1 paralogs

Van Hall-Beauvais, A.·Poganik, J. R.·Huang, K.-T.·Parvez, S.·Zhao, Y.·Lin, H.-Y.·Liu, X.·Long, M. J. C.·Aye, Y.

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Abstract

Studying electrophile signaling is marred by difficulties in parsing changes in pathway flux attributable to on-target, vis-a-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, wherein following electrophile treatment: (1) zKeap1b-transfected cells are permissive for augmented AR-signaling through reduced zKeap1b-Nrf2 binding; (2) zKeap1a-transfected cells are non-permissive for AR-upregulation, as zKeap1a-Nrf2 binding capacity remains unaltered; (3) 1:1 ZKeap1a:zKeap1b-transfected cells show no Nrf2-release from the Keap1-complex, rendering these cells unable to upregulate AR. We identified a zKeap1a-specific point-mutation (C273I) responsible for zKeap1as behavior. 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. Impact statementHow electrophile-sensing versus -signaling marshal stress responses: two zebrafish Keap1-paralogs are equally adept at electrophile-sensing but manifest divergent and co-regulatory electrophile-signaling behaviors.

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Van Hall-Beauvais, A., Poganik, J. R., Huang, K.-T., Parvez, S., Zhao, Y., Lin, H.-Y., Liu, X., Long, M. J. C., Aye, Y.. 2022-10-12. Z-REX uncovers a bifurcation in function of Keap1 paralogs. https://doi.org/10.1101/2022.10.10.511579

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