Mechanistic Investigation of the Role of FBXW7 in Inflammasome Activation

The NLRP3 inflammasome is a key regulator of inflammatory responses. These include responses to infection by pathogens but also are a component of many chronic inflammatory diseases, including neurodegenerative diseases. The end point of the inflammasome response is the secretion of mature inflammatory cytokines, IL-1β and IL-18. To accomplish this, the NLRP3 inflammasome is assembled and activated through a complex series of events, some of which remain poorly understood. The first step in NLRP3 inflammasome activation is the de novo biosynthesis of NLRP3 itself through transcriptional upregulation, and the assembly or newly synthesized NLRP3 molecules into inactive oligomers. How this occurs is only partially understood. We have evidence that the ubiquitin ligase SCFFBXW7 is required for this particular process. The objective of the proposed research is to test a hypothesis where SCFFBXW7 places ubiquitin chains on the N-terminal end of NLRP3 which are bound and capped by a UIM (ubiquitin interacting motif) near the C-terminus. The constraints enforced by this interaction would lock NLRP3 in a conformation that would promote the assembly of inactive oligomers.