Abstract: The LRRK2 locus, coding for the LRRK2 (Leucine Rich Repeat Kinase 2) protein, is a major risk factor for Parkinson’s disease (PD), and mutations in the LRRK2 gene contribute to both genetic and sporadic PD. Intriguingly, the LRRK2 locus also confers increased risk for Crohn’s disease and leprosy, and LRRK2 is expressed in immune cells, neurons and glia. We recently discovered that LRRK2 interacts with NOD-like receptor (NLR) sensor family proteins (NLRPs), NLRP1 and NLRP3. NLRP proteins are key mediators of innate immunity, and are components of inflammasomes. We propose to test the hypothesis that mutant LRRK2 interacts with and activates the NLRP3- and NLRP1-inflammasomes leading to microglial activation and neurodegeneration contributing to PD pathology. In Aim 1, we will characterize the interaction of LRRK2 with NLRP1 and NLRP3 in vitro and in vivo. In Aim 2, we will investigate whether mutant LRRK2 activates the NLRP3- infammasome in microglial activation, leading to neuroinflammation and degeneration in vitro and in vivo. In Aim3, we will examine whether mutant LRRK2 activates the NLRP1-inflammsome in neurons, resulting in neurodegeneration. These studies will elucidate mechanisms underlying LRRK2-linked inflammasome pathway in neurodegeneration and immune dysfunction. They may also have broader implications for other neurological diseases related to neuroinflammation. The understanding of NLRP/LRRK2-linked pathways in PD pathogenesis may reveal potential biomarkers, and may provide novel targets for development of disease-modifying therapeutic strategies. Thus, this project has the potential for significant impact, and benefits those suffering from PD and other neurodegenerative diseases.