Inhibition of NLRP3 inflammasome activation by A20 through modulation of NEK7

Proc Natl Acad Sci U S A. 2024 Jun 18;121(25):e2316551121. doi: 10.1073/pnas.2316551121. Epub 2024 Jun 12.

Abstract

The NLRP3 inflammasome, a pivotal component of innate immunity, has been implicated in various inflammatory disorders. The ubiquitin-editing enzyme A20 is well known to regulate inflammation and maintain homeostasis. However, the precise molecular mechanisms by which A20 modulates the NLRP3 inflammasome remain poorly understood. Here, our study revealed that macrophages deficient in A20 exhibit increased protein abundance and elevated mRNA level of NIMA-related kinase 7 (NEK7). Importantly, A20 directly binds with NEK7, mediating its K48-linked ubiquitination, thereby targeting NEK7 for proteasomal degradation. Our results demonstrate that A20 enhances the ubiquitination of NEK7 at K189 and K293 ubiquitinated sites, with K189 playing a crucial role in the binding of NEK7 to A20, albeit not significantly influencing the interaction between NEK7 and NLRP3. Furthermore, A20 disrupts the association of NEK7 with the NLRP3 complex, potentially through the OTU domain and/or synergistic effect of ZnF4 and ZnF7 motifs. Significantly, NEK7 deletion markedly attenuates the activation of the NLRP3 inflammasome in A20-deficient conditions, both in vitro and in vivo. This study uncovers a mechanism by which A20 inhibits the NLRP3 inflammasome.

Keywords: NEK7; NLRP3; TNFAIP3; ubiquitination.

MeSH terms

  • Animals
  • HEK293 Cells
  • Humans
  • Inflammasomes* / metabolism
  • Macrophages / immunology
  • Macrophages / metabolism
  • Mice
  • Mice, Knockout
  • NIMA-Related Kinases* / genetics
  • NIMA-Related Kinases* / metabolism
  • NLR Family, Pyrin Domain-Containing 3 Protein* / genetics
  • NLR Family, Pyrin Domain-Containing 3 Protein* / metabolism
  • Protein Binding
  • Tumor Necrosis Factor alpha-Induced Protein 3* / genetics
  • Tumor Necrosis Factor alpha-Induced Protein 3* / metabolism
  • Ubiquitination*

Substances

  • NIMA-Related Kinases
  • NLR Family, Pyrin Domain-Containing 3 Protein
  • Inflammasomes
  • Nek7 protein, mouse
  • Tumor Necrosis Factor alpha-Induced Protein 3
  • Tnfaip3 protein, mouse
  • Nlrp3 protein, mouse
  • NEK7 protein, human