AIM2 is an interferon-inducible protein that senses cytoplasmic DNA and activates the inflammasome, leading to caspase-1 activation and pyroptotic cell death. The study shows that AIM2, a member of the HIN-200 family, contains a pyrin domain (PYD) and an oligonucleotide/oligosaccharide-binding domain (OB domain). The OB domain binds to cytoplasmic DNA, while the PYD interacts with ASC (apoptosis-associated speck-like protein containing a CARD) to form the ASC pyroptosome, which triggers pyroptosis. AIM2 is essential for the activation of the inflammasome in response to cytoplasmic DNA, as demonstrated by knockdown experiments in human and mouse macrophages. AIM2 is also critical for the formation of the ASC pyroptosome and caspase-1 activation. The study identifies AIM2 as a key component of the inflammasome that detects potentially dangerous cytoplasmic DNA, leading to the activation of the ASC pyroptosome and caspase-1. The findings highlight the role of AIM2 in innate immune responses to microbial and viral infections, as well as tissue damage. The study also shows that AIM2 can activate caspase-1 in the absence of the NALP3 inflammasome, suggesting that AIM2 and NALP3 may serve as two distinct pathways for sensing cytoplasmic DNA. The results provide direct evidence that cytoplasmic DNA binds to AIM2 and induces its oligomerization in live cells, which is the first demonstration of an inflammasome bound to its ligand in live cells. The study also shows that AIM2 is involved in pyroptotic cell death, which is a form of programmed cell death that is important for immune responses. The findings contribute to our understanding of the mechanisms underlying the innate immune response to cytoplasmic DNA and the role of AIM2 in this process.AIM2 is an interferon-inducible protein that senses cytoplasmic DNA and activates the inflammasome, leading to caspase-1 activation and pyroptotic cell death. The study shows that AIM2, a member of the HIN-200 family, contains a pyrin domain (PYD) and an oligonucleotide/oligosaccharide-binding domain (OB domain). The OB domain binds to cytoplasmic DNA, while the PYD interacts with ASC (apoptosis-associated speck-like protein containing a CARD) to form the ASC pyroptosome, which triggers pyroptosis. AIM2 is essential for the activation of the inflammasome in response to cytoplasmic DNA, as demonstrated by knockdown experiments in human and mouse macrophages. AIM2 is also critical for the formation of the ASC pyroptosome and caspase-1 activation. The study identifies AIM2 as a key component of the inflammasome that detects potentially dangerous cytoplasmic DNA, leading to the activation of the ASC pyroptosome and caspase-1. The findings highlight the role of AIM2 in innate immune responses to microbial and viral infections, as well as tissue damage. The study also shows that AIM2 can activate caspase-1 in the absence of the NALP3 inflammasome, suggesting that AIM2 and NALP3 may serve as two distinct pathways for sensing cytoplasmic DNA. The results provide direct evidence that cytoplasmic DNA binds to AIM2 and induces its oligomerization in live cells, which is the first demonstration of an inflammasome bound to its ligand in live cells. The study also shows that AIM2 is involved in pyroptotic cell death, which is a form of programmed cell death that is important for immune responses. The findings contribute to our understanding of the mechanisms underlying the innate immune response to cytoplasmic DNA and the role of AIM2 in this process.