title: AIM2 recognizes cytosolic dsDNA and forms a caspase-1-activating inflammasome with ASC.
abstract: The innate immune system senses nucleic acids by germline-encoded pattern recognition receptors. RNA is sensed by Toll-like receptor members TLR3, TLR7 and TLR8, or by the RNA helicases RIG-I (also known as DDX58) and MDA-5 (IFIH1). Little is known about sensors for cytoplasmic DNA that trigger antiviral and/or inflammatory responses. The best characterized of these responses involves activation of the TANK-binding kinase (TBK1)-interferon regulatory factor 3 (IRF3) signalling axis to trigger transcriptional induction of type I interferon genes. A second, less well-defined pathway leads to the activation of an 'inflammasome' that, via caspase-1, controls the catalytic cleavage of the pro-forms of the cytokines IL1beta and IL18 (refs 6, 7). Using mouse and human cells, here we identify the PYHIN (pyrin and HIN domain-containing protein) family member absent in melanoma 2 (AIM2) as a receptor for cytosolic DNA, which regulates caspase-1. The HIN200 domain of AIM2 binds to DNA, whereas the pyrin domain (but not that of the other PYHIN family members) associates with the adaptor molecule ASC (apoptosis-associated speck-like protein containing a caspase activation and recruitment domain) to activate both NF-kappaB and caspase-1. Knockdown of Aim2 abrogates caspase-1 activation in response to cytoplasmic double-stranded DNA and the double-stranded DNA vaccinia virus. Collectively, these observations identify AIM2 as a new receptor for cytoplasmic DNA, which forms an inflammasome with the ligand and ASC to activate caspase-1.
authors.affiliation: Division of Infectious Diseases and Immunology, Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA. veit.hornung@uni-bonn.de
authors.forename: Veit
authors.initials: V
authors.lastname: Hornung
authors.forename: Andrea
authors.initials: A
authors.lastname: Ablasser
authors.forename: Marie
authors.initials: M
authors.lastname: Charrel-Dennis
authors.forename: Franz
authors.initials: F
authors.lastname: Bauernfeind
authors.forename: Gabor
authors.initials: G
authors.lastname: Horvath
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Caffrey
authors.forename: Eicke
authors.initials: E
authors.lastname: Latz
authors.forename: Katherine A
authors.initials: KA
authors.lastname: Fitzgerald
mesh_terms: D000818:Animals; D051017:Apoptosis Regulatory Proteins; D053468:CARD Signaling Adaptor Proteins; D020170:Caspase 1 / Q000378:metabolism*; D016923:Cell Death; D002460:Cell Line; D003598:Cytoskeletal Proteins / Q000235:genetics / Q000378:metabolism*; D003600:Cytosol / Q000378:metabolism*; D004247:DNA / Q000276:immunology / Q000378:metabolism*; D004268:DNA-Binding Proteins; D004789:Enzyme Activation; D006801:Humans; D007249:Inflammation / Q000201:enzymology / Q000378:metabolism* / Q000473:pathology; D051379:Mice; D009687:Nuclear Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011067:Poly dA-dT / Q000276:immunology; D011485:Protein Binding; D014616:Vaccinia virus / Q000276:immunology
chemical_list: C410167:AIM2 protein, human; C540422:Aim2 protein, mouse; D051017:Apoptosis Regulatory Proteins; D053468:CARD Signaling Adaptor Proteins; D003598:Cytoskeletal Proteins; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; C402202:PYCARD protein, human; C498534:Pycard protein, mouse; D011067:Poly dA-dT; D004247:DNA; D020170:Caspase 1