The NLRP3 inflammasome is a critical platform for the activation of caspase-1 and secretion of biologically
active IL-1ß and IL-18 in response to bacterial toxins, particulate matter and certain endogenous stimuli.
Furthermore, aberrant activation of NLRP3 has been linked to the pathogenesis of several acquired
inflammatory disorders including gouty arthritis, silicosis, atherosclerosis, diabetes and Alzheimer’s
disease. Although much progress has been made about the stimuli and cellular events that activate the
NLRP3 inflammasome, a major gap in the field is the identification of molecules that are required for
NLRP3 activation and the mechanism of caspase-1 activation in response to NLRP3 activating stimuli. The
Nek7 kinase was identified during the last cycle of the grant as a critical factor required for NLRP3
activation in response to a wide array of stimuli in vitro and in vivo. Nek7 was shown to act downstream of
K+ efflux to activate NLRP3. However, the mechanism by which K+ efflux activates NLRP3 via Nek7
remains unknown. Furthermore, the molecular events by which NLRP3 activates caspase-1 via the adaptor
ASC to induce ASC oligomerization and ASC speck formation are poorly understood. In this renewal
application, we propose studies in three specific Aims to (i) determine how K+ efflux activates the NLRP3
inflammasome through the kinase Nek7 using biochemical and in vivo approaches; (ii) identify factors that
regulate the phosphorylation of Nek7 to mediate the activation of NLRP3 and (iii) further characterize the
role of actin-based motor proteins in the mechanism of ASC-mediated inflammasome activation.
Understanding how NLRP3 is activated is expected to provide critical insight into the role of the
inflammasomes in different biological systems which will aid the development of new therapeutic
approaches to prevent and/or treat inflammasome-associated diseases.