Although mutations in LRRK2 are the most common genetic cause of Parkinson’s disease (PD) known, the molecular mechanism is unclear. LRRK2 protein is phosphorylated (addition of a phosphate group) at over 30 sites, including S935 and S1292. Although data suggests that LRRK2 activity can be modulated by some of these phosphorylation events, the function of most of these events is unknown. We aim at using midbrain dopaminergic (mDA) neurons to better understand the role of LRRK2 phosphorylation in PD pathogenesis.
First, we will quantify LRRK2 phosphorylation at multiple sites on mDA neurons. mDA neurons with typical or mutant LRRK2 will be subjected to different experimental conditions. We will analyze and generate a list of differentially regulated phosphorylation sites within LRRK2. Next, we will generate mutant LRRK2 constructs that remove individual phosphorylation sites from LRRK2. Then we will evaluate the PD-related observations in the presence and absence of LRRK2 phosphorylation at specific sites.
Relevance to Diagnosis/Treatment of Parkinson’s Disease:
Modulation of a few LRRK2 phosphorylation sites has been shown to ameliorate PD-related characteristics. As such, understanding the role of additional phosphorylation sites, in particular in human dopaminergic neurons, could lead to the discovery of novel biomarkers of PD. These biomarkers could assist in earlier diagnosis of PD in patients and be useful in testing new drugs. In addition, inhibition of protein phosphorylation is a well-validated strategy for development of new drugs. Therefore, understanding these LRRK2 phosphorylation events could lead to additional therapeutic targets for drug development to treat patients with PD.
This project will lead to a better understanding of how multiple LRRK2 phosphorylation sites are regulated within human mDA neurons and how this affects LRRK2 function and PD pathogenesis.