Ser1292 Autophosphorylation Is an Indicator of LRRK2 Kinase Activity and Contributes to the Cellular Effects of PD Mutations

Mutations in the leucine-rich repeat kinase 2 ( LRRK2 ) gene are the most common cause of familial Parkinson’s disease (PD). Although biochemical studies have shown that certain PD mutations confer elevated kinase activity in vitro on LRRK2, there are no methods available to directly monitor LRRK2 kinase activity in vivo. We demonstrate that LRRK2 autophosphorylation on Ser 1292 occurs in vivo and is enhanced by several familial PD mutations including N1437H, R1441G/C, G2019S, and I2020T. Combining two PD mutations together further increases Ser 1292 autophosphorylation. Mutation of Ser 1292 to alanine (S1292A) ameliorates the effects of LRRK2 PD mutations on neurite outgrowth in cultured rat embryonic primary neurons. Using cell-based and pharmacodynamic assays with phosphorylated Ser 1292 as the readout, we developed a brain-penetrating LRRK2 kinase inhibitor that blocks Ser 1292 autophosphorylation in vivo and attenuates the cellular consequences of LRRK2 PD mutations in vitro. These data suggest that Ser 1292 autophosphorylation may be a useful indicator of LRRK2 kinase activity in vivo and may contribute to the cellular effects of certain PD mutations.