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

• Published in: Cell 2021-11, Vol.184 (23), p.5759-5774.e20
• Main Authors: Shen, Chen, Li, Runzhi, Negro, Roberto, Cheng, Jiewei, Vora, Setu M., Fu, Tian-Min, Wang, Anmin, He, Kaixin, Andreeva, Liudmila, Gao, Pu, Tian, Zhigang, Flavell, Richard A., Zhu, Shu, Wu, Hao
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Animals; CARD Signaling Adaptor Proteins - metabolism; dsRNA; Hepatocytes - virology; IDRs; inflammasome; Inflammasomes - metabolism; Intestines - virology; Intrinsically Disordered Proteins - chemistry; Lipopolysaccharides - metabolism; liquid-liquid phase separation; Liver - virology; LLPS; MHV; Mice; NLRP6; Polylysine - metabolism; Protein Binding; Receptors, Cell Surface - chemistry; Receptors, Cell Surface - metabolism; RNA Viruses - physiology; RNA, Double-Stranded - metabolism; Signal Transduction; Teichoic Acids - metabolism
• ISSN: 0092-8674; 1097-4172
• DOI: 10.1016/j.cell.2021.09.032

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. [Display omitted] •dsRNA induces liquid-liquid phase separation (LLPS) of NLRP6 in vitro and in cells•ASC solidifies LLPS of NLRP6 and RNA to promote inflammasome activation•Poly-Lysine region in NLRP6 is critical for multivalent interaction and LLPS•Phase separation of NLRP6 promotes inflammasome activation in intestine and liver dsRNA induces phase separation of NLRP6 for inflammasome activation.