This proposal focuses on the study of a protein that appears to regulate inflammation, namely CIAS 1. This protein, also known as cryopyrin, is a member of a newly-described family of NBD-LRR proteins that we have identified as the CATERPILLER family. CIAS 1 mutations have been genetically associated with several autoinflammatory diseases, such as Muckle Wells Syndrome (MWS), familiar cold autoimmune syndrome (FCAS), and Chronic Infantile Neurological Cutaneous and Articular Syndromes (CINCA)/neonatal-onset multisystem inflammatory disease (NOMID). Initial characterization of the relevance of CIAS 1 has focused on its role in TLR signaling pathways and host innate immune defense mechanisms. CIAS 1 has been shown to be expressed primarily in cells of myeloid lineage. Data from our laboratory show that several agonists of the TLR pathway induce CIAS 1 expression. Initial biochemical characterizations of CIAS 1 function have been performed by transfecting expression plasmids into non-myeloid cells. These studies indicate a negative regulatory role on NFkappaB activity and therefore a role in the control of inflammatory responses. This is reminiscent of the recently described IRAK-M molecule, which is a negative regulator of endotoxin response and is induced by TLR agonist. The negative regulatory role of CIAS 1 is consistent with the presence of overzealous inflammation in autoimmune diseases where it is mutated. The objective of this proposal is to examine the function of CIAS 1 in controlling NFkB activity and therefore inflammation. To accomplish this goal, myeloid cell lines lacking CIAS 1 will be created using RNA interference (RNAi) technology. Subsequently, changes in CIAS 1 regulation of NFkappaB and the activity of inflammatory regulators in these cell lines will be examined. Lastly, mutant CIAS 1 clones recapitulating disease-associated genetic alterations will be created by site-directed mutagenesis. Consequences of these mutations on the control of NFkappaB activity and inflammation will be assessed.