title: A role for Nod-like receptors in autophagy induced by Shigella infection.
abstract: Shigella infection, the cause of bacillary dysentery, induces caspase-1 activation and cell death in macrophages, but the precise mechanisms remain poorly understood. In our recent study, we presented evidence that caspase-1 activation and IL-1beta processing induced by Shigella are mediated through Ipaf, a cytosolic pattern-recognition receptor of the nucleotide-binding oligomerization domain (NOD)-like receptor (NLR) family and the adaptor protein apoptosis-associated speck-like protein containing a C-terminal caspase recruitment domain (ASC). We also show that Ipaf and caspase-1 were critical for pyroptosis, a specialized form of caspase-1-dependent cell death induced in macrophages by bacterial infection, whereas ASC is dispensable. Notably, infection of macrophages with Shigella induced autophagy, which was dramatically increased by the absence of caspase-1 or Ipaf, but not ASC. Furthermore, autophagy induction was associated with transient resistance to pyroptosis. These results indicate that autophagy in macrophages is regulated by the Ipaf inflammasome, providing a novel function for NLR proteins in bacterial-host interactions.
authors.affiliation: Division of Bacterial Pathogenesis, Graduate School of Medicine, University of the Ryukyus, Okinawa, Japan. t-suzuki@med.u-ryukyu.ac.jp
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Suzuki
authors.forename: Gabriel
authors.initials: G
authors.lastname: Núñez
mesh_terms: D000818:Animals; D051017:Apoptosis Regulatory Proteins / Q000235:genetics / Q000378:metabolism; D001343:Autophagy / Q000502:physiology*; D053468:CARD Signaling Adaptor Proteins; D002135:Calcium-Binding Proteins / Q000235:genetics / Q000378:metabolism; D020170:Caspase 1 / Q000378:metabolism; D003598:Cytoskeletal Proteins / Q000378:metabolism; D004405:Dysentery, Bacillary / Q000378:metabolism*; D004789:Enzyme Activation; D008264:Macrophages / Q000378:metabolism; D053472:Nod Signaling Adaptor Proteins / Q000378:metabolism*; D012763:Shigella flexneri / Q000378:metabolism* / Q000472:pathogenicity
chemical_list: D051017:Apoptosis Regulatory Proteins; D053468:CARD Signaling Adaptor Proteins; D002135:Calcium-Binding Proteins; D003598:Cytoskeletal Proteins; C512299:Ipaf protein, mouse; D053472:Nod Signaling Adaptor Proteins; C498534:Pycard protein, mouse; D020170:Caspase 1