Novel LRRK2 Kinase Inhibitors Enhance Phosphorylation and Restore Adapter Protein Binding in LRRK2 Variants

Autosomal dominant mutations in LRRK2 that increase kinase activity significantly increase the risk of developing Parkinson's disease (PD). Efforts to reduce the resulting hyperphosphorylation have focused mainly on small-molecule type I kinase inhibitors (KIs); however, these bind the active, closed conformation of the LRRK2 kinase domain, which affects protein tertiary structure and can alter other functions of this multi-domain protein. Because disruption of these functions may contribute to pathogenesis independently of, or in addition to, augmented kinase activity, inhibitors that engage LRRK2 differently may offer an advantage. We hypothesize that KIs, which bind distinct conformations of LRRK2 and modulate non-kinase functions differently than type I inhibitors, may be beneficial. Here we tested two series of LRRK2 inhibitors, based on hesperadin (series A) and GNF-7 (series B), which each inhibited LRRK2 kinase activity in biochemical and cellular assays while differing in effects on other LRRK2 functions. Interestingly, series B compounds enhanced phosphorylation of interdomain heterologous phosphosites and restored 14-3-3 binding in LRRK2 variants with suppressed phosphorylation. These chemotypes provide tools for dissecting the consequences of different inhibitor-bound LRRK2 conformations and support conformation-selective inhibition as a therapeutic strategy for PD.