The past two decades in research has revealed the importance of leucine-rich repeat kinase 2 (LRRK2) in both monogenic and sporadic forms of Parkinson's disease (PD). In families, mutations in LRRK2 can cause PD with age-dependent but variable penetrance and genome-wide association studies have found variants of the gene that are risk factors for sporadic PD. Functional studies have suggested that the common mechanism that links all disease-associated variants is that they increase LRRK2 kinase activity, albeit in different ways. Here, we will discuss the roles of LRRK2 in areas of inflammation and vesicular trafficking in the context of monogenic and sporadic PD. We will also provide a hypothetical model that links inflammation and vesicular trafficking together in an effort to outline how these pathways might interact and eventually lead to neuronal cell death. We will also highlight the translational potential of LRRK2-specific kinase inhibitors for the treatment of PD.
Mutations in the leucine-rich repeat kinase 2 (LRRK2) gene, associated with Parkinson's disease, have been shown to affect intracellular trafficking pathways in a variety of cells and organisms. An emerging theme is that LRRK2 can bind to multiple membranous structures in cells, and several recent studies have suggested that the Rab family of small GTPases might be important in controlling the recruitment of LRRK2 to specific cellular compartments. Once localized to membranes, LRRK2 then influences downstream events, evidenced by changes in the autophagy–lysosome pathway. Here, I will discuss available evidence that supports or challenges this outline, with a specific emphasis on those aspects of LRRK2 function that have been controversial or remain to be fully clarified.
Mutations in LRRK2 (leucine-rich repeat kinase 2) are a relatively common cause of inherited PD (Parkinson's disease), but the mechanism(s) by which mutations lead to disease are poorly understood. In the present paper, I discuss what is known about LRRK2 in cellular models, focusing specifically on assays that have been used to tease apart the effects of LRRK2 mutations on cellular phenotypes. LRRK2 expression has been suggested to cause loss of neuronal viability, although because it also has a strong effect on the length of neurites on these cells, whether this is true toxicity or not is unclear. Also, LRRK2 mutants can promote the redistribution of LRRK2 from diffuse cytosolic staining to more discrete structures, at least at high expression levels achieved in transfection experiments. The relevance of these phenotypes for PD is not yet clear, and a great deal of work is needed to understand them in more depth.