Phase separation drives RNA virus-induced activation of the NLRP6 inflammasome

Cell. 2021 Nov 11;184(23):5759-5774.e20. doi: 10.1016/j.cell.2021.09.032. Epub 2021 Oct 21.

Abstract

NLRP6 is important in host defense by inducing functional outcomes including inflammasome activation and interferon production. Here, we show that NLRP6 undergoes liquid-liquid phase separation (LLPS) upon interaction with double-stranded RNA (dsRNA) in vitro and in cells, and an intrinsically disordered poly-lysine sequence (K350-354) of NLRP6 is important for multivalent interactions, phase separation, and inflammasome activation. Nlrp6-deficient or Nlrp6K350-354A mutant mice show reduced inflammasome activation upon mouse hepatitis virus or rotavirus infection, and in steady state stimulated by intestinal microbiota, implicating NLRP6 LLPS in anti-microbial immunity. Recruitment of ASC via helical assembly solidifies NLRP6 condensates, and ASC further recruits and activates caspase-1. Lipoteichoic acid, a known NLRP6 ligand, also promotes NLRP6 LLPS, and DHX15, a helicase in NLRP6-induced interferon signaling, co-forms condensates with NLRP6 and dsRNA. Thus, LLPS of NLRP6 is a common response to ligand stimulation, which serves to direct NLRP6 to distinct functional outcomes depending on the cellular context.

Keywords: IDRs; LLPS; MHV; NLRP6; RV; dsRNA; inflammasome; liquid-liquid phase separation.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • CARD Signaling Adaptor Proteins / metabolism
  • Hepatocytes / virology
  • Inflammasomes / metabolism*
  • Intestines / virology
  • Intrinsically Disordered Proteins / chemistry
  • Lipopolysaccharides / metabolism
  • Liver / virology
  • Mice
  • Polylysine / metabolism
  • Protein Binding
  • RNA Viruses / physiology*
  • RNA, Double-Stranded / metabolism
  • Receptors, Cell Surface / chemistry
  • Receptors, Cell Surface / metabolism*
  • Signal Transduction
  • Teichoic Acids / metabolism

Substances

  • CARD Signaling Adaptor Proteins
  • Inflammasomes
  • Intrinsically Disordered Proteins
  • Lipopolysaccharides
  • Nod-like receptor pyrin domain-containing protein 6, mouse
  • Pycard protein, mouse
  • RNA, Double-Stranded
  • Receptors, Cell Surface
  • Teichoic Acids
  • Polylysine
  • lipoteichoic acid