Assessing molecular and cellular consequences of the LRRK2:14-3-3 complex

Parkinson’s disease (PD) is the second most common progressive neurodegenerative disorder. The Leucine Rich Repeat Kinase 2 (LRRK2) gene is mutated in some familial PD cases and in idiopathic PD. Most LRRK2-PD mutations result in a protein with increased kinase activity. LRRK2 kinase inhibitors revert disease-associated phenotypes in cells, but they can cause abnormalities in LRRK2-expressing tissues. When interacting with 14-3-3, LRRK2 is maintained in a less active cytosolic form. This LRRK2:14-3-3 complex requires the phosphorylation of serine 910 and serine 935 within LRRK2, which is decreased in PD-associated mutants. Therefore, our working hypothesis is that preserving the LRRK2:14-3-3 complex is beneficial against PD. In this work, biomolecular and cellular phenotypes of the LRRK2:14-3-3 complex have been determined, with the aim of assessing in the future the activity of compounds able to increase the affinity of the complex. Phenotypes of phospho-dead and phospho-mimicking LRRK2 mutants have also been studied, to develop reliable controls of the interaction. Our results show that a 6xS>A phospho-dead mutant is a valid negative control, but do not validate a phospho-mimicking 6x>SD LRRK2 as a positive control. These results could help the development of effective new treatments for PD, by modulating LRRK2 activity via its interactors.