My overall aim is to define the role of NOD-like receptors (NLRs) in immunity and to understand the importance of their signaling networks in health and disease.NLR family members are thought to sense pathogens and endogenous alarmins in intracellular compartments to trigger innate immune responses. Recent progress was made in mapping the signaling pathways of the NLRs Nod1, Nod2 and Nlrp3, but the roles and signaling cascades of most other NLRs remain unclear. Indeed, the NLRs Ipaf and Nlrp1b assemble caspase-1-activating inflammasome complexes, but the molecular events leading to Ipaf and Nlrp1b activation remain enigmatic. Similarly, mutations in the NLR Nlrp12 are associated with auto-inflammation, but the precise molecular functions and signaling networks of this NLR require further study.To increase our understanding of the role and signaling pathways of Ipaf, Nlrp1b and Nlrp12, my first aim is to define the subcellular localization and co-regulated genes of these NLRs in naive and activated immune cells. In the second aim, I will define and validate the interactomes of Nlrp1b, Ipaf and Nlrp12 in immune cells from Ipaf, Nlrp1b and Nlrp12 mutant mice. In my third aim, these results will be used to map the activation mechanisms of the Nlrp1b and Ipaf inflammasomes in macrophages intoxicated with anthrax lethal toxin or infected with Salmonella, respectively; and to define the role of Nlrp12 and its interaction partners in innate immune signaling.To approach these aims, I will combine enabling proteomics approaches such as the proprietary mass spectrometry-based COFRADIC technology and interactome technologies such as MAPPIT with detailed biochemical and cell biological studies in NLR knockout cells and mice.Given the importance of NLRs in infection and autoimmunity, characterization of the activation and signaling pathways of Nlrp1b, Ipaf and Nlrp12 is likely to have far-reaching implications for our understanding of host defense and the immune response.