GTP binding regulates cellular localization of Parkinsońs disease-associated LRRK2

Mutations in LRRK2 comprise the most common cause of familial Parkinsońs disease (PD), and sequence variants modify risk for sporadic PD. Previous studies indicate that LRRK2 interacts with microtubules and alters microtubule-mediated vesicular transport processes. However, the molecular determinants within LRRK2 required for such interactions have remained unknown. Here we report that most pathogenic LRRK2 mutants cause relocalization of LRRK2 to filamentous structures which colocalize with a subset of microtubules, and an identical relocalization is seen upon pharmacological LRRK2 kinase inhibition. The pronounced colocalization with microtubules does not correlate with alterations in LRRK2 kinase activity, but rather with increased GTP binding. Synthetic mutations which impair GTP binding, as well as LRRK2 GTP-binding inhibitors profoundly interfere with the abnormal localization of both pathogenic mutant as well as kinase-inhibited LRRK2. Conversely, addition of a non-hydrolyzable GTP analog to permeabilized cells enhances the association of pathogenic or kinase-inhibited LRRK2 with microtubules. Our data elucidate the mechanism underlying the increased microtubule association of select pathogenic LRRK2 mutants or of pharmacologically kinase-inhibited LRRK2, with implications for downstream MT-mediated transport events.