Promising Outcomes of Original Grant:
We have verified that LRRK2 undergoes key changes that affect LRRK2 structure and LRRK2 membrane localization. We have generated a large set of LRRK2 variants (mutations) that are available to the Parkinson's disease (PD) research community to test specific LRRK2 amino acids for LRRK2 localization and function. Using these variants, we have determined that at least two structural sites of LRRK2 undergo changes that regulate LRRK2 membrane localization. We found that these changes to LRRK2 also increased the specific association of LRRK2 with cholesterol-rich membrane domains, commonly termed "lipid rafts," and extended the life of the protein by protecting it from enzyme break down.
Objectives for Supplemental Investigation:
The primary objective of our supplemental study is to use mass spectrometry (technique used to sort chemicals) to identify specific sites on LRRK2 that are responsible for the localization of LRRK2 with lipid rafts and other cellular membranes. Additional objectives include improving methods for isolating LRRK2 from lipid rafts and other cellular membranes to analyze stimulus-dependent changes to LRRK2. These studies will potentially increase the likelihood of successfully identifying sites of LRRK2 changes using mass spectrometry.
Importance of This Research for the Development of a New PD Therapy:
Mutations in LRRK2 are the most common cause of familial Parkinson's (form of PD that is inherited). Although the mechanisms by which LRRK2 mutations are linked to PD are unclear, studies indicate that LRRK2 mutations increase the kinase (protein regulation) activity of LRRK2 and that kinase activity is required for LRRK2-mediated cell toxicity. Because LRRK2 kinase activity is dependent upon LRRK2 membrane localization, our studies may identify novel therapeutic targets to lessen the effects of LRRK2 mutations linked to Parkinson's.