RESUMEN
NLRP1 is an innate immune receptor that detects pathogen-associated signals, assembles into a multiprotein structure called an inflammasome, and triggers a proinflammatory form of cell death called pyroptosis. We previously discovered that the oxidized, but not the reduced, form of thioredoxin-1 directly binds to NLRP1 and represses inflammasome formation. However, the molecular basis for NLRP1's selective association with only the oxidized form of TRX1 has not yet been established. Here, we leveraged AlphaFold-Multimer, site-directed mutagenesis, thiol-trapping experiments, and mass spectrometry to reveal that a specific cysteine residue (C427 in humans) on NLRP1 forms a transient disulfide bond with oxidized TRX1. Overall, this work demonstrates how NLRP1 monitors the cellular redox state, further illuminating an unexpected connection between the intracellular redox potential and the innate immune system.
Asunto(s)
Proteínas Adaptadoras Transductoras de Señales , Disulfuros , Proteínas NLR , Oxidación-Reducción , Tiorredoxinas , Humanos , Disulfuros/química , Disulfuros/metabolismo , Tiorredoxinas/metabolismo , Tiorredoxinas/química , Proteínas NLR/metabolismo , Proteínas NLR/química , Proteínas Adaptadoras Transductoras de Señales/metabolismo , Proteínas Adaptadoras Transductoras de Señales/química , Células HEK293 , Proteínas Reguladoras de la Apoptosis/metabolismo , Proteínas Reguladoras de la Apoptosis/química , Inflamasomas/metabolismo , Cisteína/metabolismo , Cisteína/químicaRESUMEN
NLRP1 is an innate immune receptor that detects pathogen-associated signals, assembles into a multiprotein structure called an inflammasome, and triggers a proinflammatory form of cell death called pyroptosis. We previously discovered that the oxidized, but not the reduced, form of thioredoxin-1 directly binds to NLRP1 and represses inflammasome formation. However, the molecular basis for NLRP1's selective association with only the oxidized form of TRX1 has not yet been established. Here, we leveraged Alphafold-Multimer, site-directed mutagenesis, thiol-trapping experiments, and mass spectrometry to reveal that a specific cysteine residue (C427 in humans) on NLRP1 forms a transient disulfide bond with oxidized TRX1. Overall, this work demonstrates how NLRP1 monitors the cellular redox state, further illuminating an unexpected connection between the intracellular redox potential and the innate immune system.
RESUMEN
The danger signals that activate the NLRP1 inflammasome have not been established. Here, we report that the oxidized, but not the reduced, form of thioredoxin-1 (TRX1) binds to NLRP1. We found that oxidized TRX1 associates with the NACHT-LRR region of NLRP1 in an ATP-dependent process, forming a stable complex that restrains inflammasome activation. Consistent with these findings, patient-derived and ATPase-inactivating mutations in the NACHT-LRR region that cause hyperactive inflammasome formation interfere with TRX1 binding. Overall, this work strongly suggests that reductive stress, the cellular perturbation that will eliminate oxidized TRX1 and abrogate the TRX1-NLRP1 interaction, is a danger signal that activates the NLRP1 inflammasome.
