Involved in innate immune response by recognizing cytosolic double-stranded DNA and inducing caspase-1-activating inflammasome formation in macrophages (PubMed:17726700, PubMed:19158675, PubMed:19158676, PubMed:19158679, PubMed:20566831). Upon binding to DNA is thought to undergo oligomerization and to associate with PYCARD initiating the recruitment of caspase-1 precursor and processing of interleukin-1 beta and interleukin-18 (PubMed:17726700, PubMed:19158675, PubMed:19158676, PubMed:19158679, PubMed:20566831). Detects cytosolic dsDNA of viral and bacterial origin in a non-sequence-specific manner (PubMed:17726700, PubMed:19158675, PubMed:19158676, PubMed:19158679, PubMed:20566831). Also acts as a mediator of pyroptosis, necroptosis and apoptosis (PANoptosis), an integral part of host defense against pathogens, in response to bacterial infection (By similarity). Can also trigger PYCARD-dependent, caspase-1-independent cell death that involves caspase-8 (By similarity). Tumor suppressor which may act by repressing NF-kappa-B transcriptional activity (PubMed:16432157). In absence of dsDNA pyrin and HIN-20 domain can interact inducing a closed conformation; an autoinhibitory mechanism is proposed in which binding to dsDNA liberates the pyrin domain for homotypic downstream signaling interactions with PYCARD. Self-associates; forms homooligomers in response to cytosolic dsDNA and the dsDNA seems to serve as oligomerization platform (PubMed:15582594, PubMed:19158676). Component of the AIM2 inflammasome (PubMed:22869553, PubMed:22483801). Interacts with PYCARD, IFI16, EIF2AK2/PKR and MAPRE1 (PubMed:19158676, PubMed:19158675, PubMed:19158679, PubMed:22046441, PubMed:22801494, PubMed:22869553). Interacts with PYDC5; disrupts assembly of the ALR inflammasome complex (PubMed:24531343). Component of the AIM2 PANoptosome complex, a multiprotein complex that drives inflammatory cell death (PANoptosis) (By similarity). Activated inflammasomes can aggregate in the cytosol as speck-like particles. Expressed in spleen, small intestine, peripheral blood leukocytes, and testis. By IFNG/IFN-gamma and IFNB1/IFN-beta. The pyrin domain mediates homotypic interaction with PYCARD (PubMed:19158676, PubMed:19158675). The HIN-20 domain mediates dsDNA binding via electrostatic interactions. Defects in AIM2 may be a cause of microsatellite unstable colon cancers. Belongs to the HIN-200 family.