Harake A., CHUM Research Center

Harake A. 1,2 ; Zamorano-Cuervo N. 1,2 ; Caron E. 1 ; Dufresne S. ; Fortin A. 1 and Grandvaux N. 1,2 / 1)CRCHUM, Montreal, Quebec, CA ; 2)University of Montreal, Quebec, CA

Fighting & Responding

Introduction: Airway epithelial cells are a first line of defense against respiratory RNA viruses such as respiratory syncytial virus and SARS-CoV-2, producing type I/III interferons and proinflammatory cytokines that restrict infection. Reactive oxygen species influence these responses, but the redox mechanisms controlling antiviral signaling remain incompletely defined. MAVS is a central mitochondrial adaptor downstream of RIG-I-like receptors that oligomerizes upon activation to drive antiviral gene induction. As thiol peroxidases that shape peroxide signaling and relay redox changes to protein targets, peroxiredoxins (PRDXs) are strong candidates to control MAVS redox state and signaling output. Hypothesis: PRDX1/2 modulate MAVS cysteine oxidation and thereby tune MAVS-dependent antiviral signaling. Methods/Results: Using cysteine-reactive labeling approaches, we detect MAVS cysteine oxidation under conditions that potentiate antiviral signaling, and mutational disruption of MAVS N-terminal cysteines reduces MAVS-dependent signaling outputs, supporting a functional requirement for these residues. PRDX1/2 are expressed in human epithelial cell models, and co-immunoprecipitation supports interactions between MAVS and PRDX1/2. Work in progress, shows that pharmacological inhibition of PRDX1/2 with Conoidin A potentiates MAVS-dependent signaling. Inhibition of thioredoxin reductase with Auranofin, a perturbation of the TrxR–PRDX redox axis, increases MAVS cysteine oxidation. To test whether PRDX1 catalytic activity is required, CRISPR-Cas9 engineered HEK293T PRDX1-deficient cells were complemented with PRDX1 wild-type or a catalytically inactive mutant (C52S/C173S); analysis of antiviral outputs in these lines is in progress. Conclusion: Together, this work in progress supports a model in which the PRDX redox axis calibrates innate immune output by modulating functionally important MAVS cysteine oxidation.