title: A20 restricts ubiquitination of pro-interleukin-1β protein complexes and suppresses NLRP3 inflammasome activity.
abstract: Inappropriate inflammasome activation contributes to multiple human diseases, but the mechanisms by which inflammasomes are suppressed are poorly understood. The NF-κB inhibitor A20 is a ubiquitin-modifying enzyme that might be critical in preventing human inflammatory diseases. Here, we report that A20-deficient macrophages, unlike normal cells, exhibit spontaneous NLRP3 inflammasome activity to LPS alone. The kinase RIPK3, but not the adaptor MyD88, is required for this response. In normal cells, A20 constitutively associates with caspase-1 and pro-IL-1β, and NLRP3 activation further promotes A20 recruitment to the inflammasome. Pro-IL-1β also co-immunoprecipitates with RIPK1, RIPK3, caspase-1, and caspase-8 in a complex that is modified with K63-linked and unanchored polyubiquitin. In A20-deficient macrophages, this pro-IL-1β-associated ubiquitination is markedly increased in a RIPK3-dependent manner. Mass spectrometric and mutational analyses reveal that K133 of pro-IL-1β is a physiological ubiquitination site that supports processing. Our study reveals a mechanism by which A20 prevents inflammatory diseases.
authors.affiliation: Department of Medicine, University of California, San Francisco, San Francisco, CA 94143, USA.
authors.forename: Bao H
authors.initials: BH
authors.lastname: Duong
authors.affiliation: Department of Medicine, University of California, San Francisco, San Francisco, CA 94143, USA.
authors.forename: Michio
authors.initials: M
authors.lastname: Onizawa
authors.affiliation: Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, CA 94143, USA.
authors.forename: Juan A
authors.initials: JA
authors.lastname: Oses-Prieto
authors.affiliation: Department of Medicine, University of California, San Francisco, San Francisco, CA 94143, USA.
authors.forename: Rommel
authors.initials: R
authors.lastname: Advincula
authors.affiliation: Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, CA 94143, USA.
authors.forename: Alma
authors.initials: A
authors.lastname: Burlingame
authors.affiliation: Department of Medicine, University of California, San Francisco, San Francisco, CA 94143, USA.
authors.forename: Barbara A
authors.initials: BA
authors.lastname: Malynn
authors.affiliation: Department of Medicine, University of California, San Francisco, San Francisco, CA 94143, USA. Electronic address: averil.ma@ucsf.edu.
authors.forename: Averil
authors.initials: A
authors.lastname: Ma
mesh_terms: D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism*; D002460:Cell Line; D003546:Cysteine Endopeptidases / Q000235:genetics / Q000378:metabolism*; D004252:DNA Mutational Analysis; D007108:Immune Tolerance; D058847:Inflammasomes / Q000276:immunology*; D053583:Interleukin-1beta / Q000235:genetics / Q000378:metabolism*; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D008264:Macrophages / Q000502:physiology*; D051379:Mice; D008815:Mice, Inbred Strains; D018345:Mice, Knockout; D046912:Multiprotein Complexes / Q000378:metabolism; D000071199:NLR Family, Pyrin Domain-Containing 3 Protein; D053422:Receptor-Interacting Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D000072598:Tumor Necrosis Factor alpha-Induced Protein 3; D054875:Ubiquitination / Q000235:genetics
chemical_list: D002352:Carrier Proteins; D058847:Inflammasomes; D053583:Interleukin-1beta; D047908:Intracellular Signaling Peptides and Proteins; D046912:Multiprotein Complexes; D000071199:NLR Family, Pyrin Domain-Containing 3 Protein; C492716:Nlrp3 protein, mouse; D053422:Receptor-Interacting Protein Serine-Threonine Kinases; C485615:Ripk3 protein, mouse; D000072598:Tumor Necrosis Factor alpha-Induced Protein 3; D003546:Cysteine Endopeptidases; C513261:Tnfaip3 protein, mouse