LRRK2 inhibitors as a possible drug therapy for Parkinson's disease

Abstract

Parkinson’s disease (PD) is a neurodegenerative disorder that is characterized by motor and cognitive dysfunction including resting tremor, rigidity, bradykinesia, and depression. Current treatment options including L-DOPA, MAO-B inhibitors, and dopamine agonists only affect PD symptoms and do not modify disease progression. Although PD is primarily sporadic in nature recent studies have targeted mutations in the leucine-rich repeat kinase 2 (LRRK2) gene as a genetic cause of PD. The most common mutation is G2019S, which is associated with increased kinase activity and disruption of phosphorylation mechanisms. This mutation is a potential therapeutic drug target via LRRK2 kinase inhibitors (LRRK2-In-1, MLi-2, GNE-7915, and GNE-0877). Recent studies have shown adverse side effects in peripheral tissues as well as decreases in LRRK2 protein concentration in brain lysates. To expand on this finding, this project sought to determine the effect of kinase inhibition in a living dopaminergic-like cell line transfected with LRRK2(WT)-EGFP or LRRK2(G2019S)-EGFP. Alterations in protein dynamics after treatment were measured using advanced fluorescence microscopy with total internal reflection fluorescence microscopy (TIRF) and 2 photon confocal microscopy. Our data show alterations in protein concentration and oligomerization state of WT LRRK2 that is more indicative of G2019S rather than WT function suggesting higher levels of self-association in the cytosol and at the membrane after treatment. This finding was further exaggerated in G2019S expressing cells. This project uncovered novel changes in LRRK2 function after treatment suggesting that additional characterization of kinase inhibitor function is needed before drug approval.