Posttranslational ISGylation of NLRP3 by HERC enzymes facilitates inflammasome activation in models of inflammation
Ying Qin, … , Chunyuan Zhao, Wei Zhao
Ying Qin, … , Chunyuan Zhao, Wei Zhao
Published August 31, 2023
Citation Information: J Clin Invest. 2023;133(20):e161935. https://doi.org/10.1172/JCI161935.
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Research Article Immunology Inflammation

Posttranslational ISGylation of NLRP3 by HERC enzymes facilitates inflammasome activation in models of inflammation

Abstract

The NOD-, LRR-, and pyrin domain–containing protein 3 (NLRP3) inflammasome is a crucial component of the innate immune system that initiates inflammatory responses. Posttranslational modifications (PTMs) of NLRP3, including ubiquitination and phosphorylation, control inflammasome activation and determine the intensity of inflammation. However, the role of other PTMs in controlling NLRP3 inflammasome activation remains unclear. This study found that TLR priming induced NLRP3 ISGylation (a type of PTM in which ISG15 covalently binds to the target protein) to stabilize the NLRP3 protein. Viral infection, represented by SARS-COV-2 infection, and type I IFNs induced expression of ISG15 and the predominant E3 ISGylation ligases HECT domain- and RCC1-like domain–containing proteins (HERCs; HERC5 in humans and HERC6 in mice). HERCs promoted NLRP3 ISGylation and inhibited K48-linked ubiquitination and proteasomal degradation, resulting in the enhancement of NLRP3 inflammasome activation. Concordantly, Herc6 deficiency ameliorated NLRP3-dependent inflammation as well as hyperinflammation caused by viral infection. The results illustrate the mechanism by which type I IFNs responses control inflammasome activation and viral infection–induced aberrant NLRP3 activation. This work identifies ISGylation as a PTM of NLRP3, revealing a priming target that modulates NLRP3-dependent immunopathology.

Authors

Ying Qin, Xintong Meng, Mengge Wang, Wenbo Liang, Rong Xu, Jingchunyu Chen, Hui Song, Yue Fu, Jingxin Li, Chengjiang Gao, Mutian Jia, Chunyuan Zhao, Wei Zhao

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Figure 6

Herc6 deficiency ameliorates NLRP3-dependent inflammation in vivo.

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Herc6 deficiency ameliorates NLRP3-dependent inflammation in vivo. (A) ...
(A) ELISA analysis of serum levels of IL-1β, TNF-α, and IL-6 of Herc6+/+ or Herc6–/– mice after i.p. LPS injection for 4 hours (PBS n = 3, LPS, n = 6 per group; 2-tailed t test, Herc6+/+ vs. Herc6–/–, **P = 0.005057). (B and C) ELISA analysis of serum (B) or BALF (C) IL-1β levels of Herc6+/+ or Herc6–/– mice after i.p. LPS injection for 12 hours (PBS n = 3; LPS n = 5 per group; 2-tailed t test, Herc6+/+ vs. Herc6–/–, B: ***P = 1.36 × 10–4, C: ***P = 3.84 × 10–5). (D) WBC count in BALF of IL-1β of Herc6+/+ or Herc6–/– mice after i.p. LPS injection for 12 hours (PBS n = 2, LPS, n = 6 per group; 2-tailed t test, Herc6+/+ vs. Herc6–/–, *P = 0.031741). (E and F) Immunoblot analysis of lysates from the lung, spleen, and liver of Herc6+/+ or Herc6–/– mice after i.p. LPS injection for 12 hours. NLRP3 expression was quantitated by measuring band intensities using ImageJ software. The values were normalized to actin (PBS n = 2, LPS n = 5 per group; 2-tailed t test, Herc6+/+ vs. Herc6–/–, lung: *P = 0.025147, spleen: **P = 0.007801, liver: *P = 0.040026). (G) H&E staining of lung tissue sections from Herc6+/+ or Herc6–/– mice after i.p. LPS injection for 12 hours (PBS n = 2, LPS n = 4 per condition). Scale bars: 10 μm. All data are presented as mean ± SD in A–D and F. Similar results were obtained from 3 independent experiments.