Oxidized thioredoxin-1 restrains the NLRP1 inflammasome

Abstract

At least six human proteins detect danger-associated signals, assemble into complexes called inflammasomes, and trigger pyroptotic cell death. NLRP1 was the first protein discovered to form an inflammasome, but the danger signals and molecular mechanisms that control its activation have not yet been fully established. Here, we report that the NACHT-LRR region of NLRP1 directly binds to oxidized form of thioredoxin-1 (TRX1). We found that NLRP1 requires the ATPase activity of its NACHT domain to associate with TRX1, and that this interaction represses inflammasome activation. Moreover, we discovered that several patient-derived missense mutations in the NACHT-LRR region of NLRP1 weaken TRX1 binding, leading to inflammasome hyperactivation and autoinflammatory disease. Overall, our results establish that oxidized TRX1 binds to and restrains the NLRP1 inflammasome, thereby revealing a link between the cellular redox environment and innate immunity.

The NLRP1 and CARD8 inflammasomes detect reductive stress

“…MeBs, which synergizes with VbP to induce more pyroptosis in these cell lines, was used as a positive control in this experiment (Chui et al, 2019; Orth-He et al, 2022). Consistent with our previous results (Ball et al, 2021), we found that dithiothreitol (DTT), N-acetyl cysteine (NAC), reduced L-glutathione (GSH), and trolox did not impact VbP-induced NLRP1 or CARD8 activation ( Fig. 1A,B , Fig.…”

“…CRISPR/Cas9 gene editing. DPP8/9, CARD8, and CASP1 knockout THP-1 cell lines and all HEK293T, RAW 264.7, N/TERT-1, and MV4;11 knockout cell lines were generated as previously described (Ball et al, 2021;Johnson et al, 2018;Okondo et al, 2017;Sharif et al, 2021). Briefly, 5´ 10 5 HEK 293T cells stably expressing Cas9 were seeded in 6-well tissue culture dishes in 2 mL of media per well.…”

“…Cell lines were regularly tested for mycoplasma using the MycoAlert Mycoplasma Detection Kit (Lonza). CARD8 −/− , DPP8 −/− /DPP9 −/− , and CASP1 −/− THP-1 cells, CASP1 −/− and Nlrp1b −/− RAW 264.7 cells, CARD8 −/− , and CASP1 −/− MV4;11, NLRP1 −/− N/TERT-1 cells were generated as previously described (Ball et al, 2021;Johnson et al, 2018;Okondo et al, 2017). Doxycycline (DOX)-inducible CARD8 and NLRP1 WT and mutant knock-in CARD8 −/− THP-1 were generated as previously described (Hollingsworth et al, 2021;Sharif et al, 2021).…”

“…Briefly, NLRP1 has NT nucleotide-binding (NACHT) and leucine-rich (LRR) domains (Fig. S1), and these domains associate with the oxidized form of thioredoxin-1 (TRX1) (Ball et al, 2021).…”

“…Briefly, NLRP1 has NT nucleotide-binding (NACHT) and leucine-rich (LRR) domains ( Fig. S1 ), and these domains associate with the oxidized form of thioredoxin-1 (TRX1) (Ball et al, 2021). We found that genetic loss of TRX1 sensitizes cells to VbP-induced pyroptosis, showing that oxidized TRX1 restrains NLRP1 activation.…”