title: Site-specific phosphorylation and microtubule dynamics control Pyrin inflammasome activation.
abstract: Pyrin, encoded by the MEFV gene, is best known for its gain-of-function mutations causing familial Mediterranean fever (FMF), an autoinflammatory disease. Pyrin forms a caspase-1-activating inflammasome in response to inactivating modifications of Rho GTPases by various bacterial toxins or effectors. Pyrin-mediated innate immunity is unique in that it senses bacterial virulence rather than microbial molecules, but its mechanism of activation is unknown. Here we show that Pyrin was phosphorylated in bone marrow-derived macrophages and dendritic cells. We identified Ser-205 and Ser-241 in mouse Pyrin whose phosphorylation resulted in inhibitory binding by cellular 14-3-3 proteins. The two serines underwent dephosphorylation upon toxin stimulation or bacterial infection, triggering 14-3-3 dissociation, which correlated with Pyrin inflammasome activation. We developed antibodies specific for phosphorylated Ser-205 and Ser-241, which confirmed the stimuli-induced dephosphorylation of endogenous Pyrin. Mutational analyses indicated that both phosphorylation and signal-induced dephosphorylation of Ser-205/241 are important for Pyrin activation. Moreover, microtubule drugs, including colchicine, commonly used to treat FMF, effectively blocked activation of the Pyrin inflammasome. These drugs did not affect Pyrin dephosphorylation and 14-3-3 dissociation but inhibited Pyrin-mediated apoptosis-associated Speck-like protein containing CARD (ASC) aggregation. Our study reveals that site-specific (de)phosphorylation and microtubule dynamics critically control Pyrin inflammasome activation, illustrating a fine and complex mechanism in cytosolic immunity.
authors.affiliation: College of Biological Sciences, China Agricultural University, Beijing 100094, China; National Institute of Biological Sciences, Beijing 102206, China;
authors.forename: Wenqing
authors.initials: W
authors.lastname: Gao
authors.affiliation: National Institute of Biological Sciences, Beijing 102206, China;
authors.forename: Jieling
authors.initials: J
authors.lastname: Yang
authors.affiliation: National Institute of Biological Sciences, Beijing 102206, China;
authors.forename: Wang
authors.initials: W
authors.lastname: Liu
authors.affiliation: National Institute of Biological Sciences, Beijing 102206, China;
authors.forename: Yupeng
authors.initials: Y
authors.lastname: Wang
authors.affiliation: National Institute of Biological Sciences, Beijing 102206, China; Collaborative Innovation Center for Cancer Medicine, National Institute of Biological Sciences, Beijing 102206, China shaofeng@nibs.ac.cn.
authors.forename: Feng
authors.initials: F
authors.lastname: Shao
mesh_terms: D048948:14-3-3 Proteins / Q000378:metabolism; D000818:Animals; D001427:Bacterial Toxins / Q000494:pharmacology; D004768:Enterotoxins / Q000494:pharmacology; D057809:HEK293 Cells; D006801:Humans; D058847:Inflammasomes / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D008870:Microtubules / Q000502:physiology*; D010766:Phosphorylation; D000071198:Pyrin / Q000378:metabolism*; D050257:Tubulin Modulators / Q000494:pharmacology
chemical_list: D048948:14-3-3 Proteins; D001427:Bacterial Toxins; D004768:Enterotoxins; D058847:Inflammasomes; D000071198:Pyrin; D050257:Tubulin Modulators; C041348:tcdA protein, Clostridium difficile
keywords: FMF; Pyrin; Rho toxins; inflammasome; phosphorylation