Lysosomal stress drives the release of pathogenic α-synuclein from macrophage lineage cells via the LRRK2-Rab10 pathway.

α-Synuclein and LRRK2 are associated with both familial and sporadic Parkinson's disease (PD), although the mechanistic link between these two proteins has remained elusive. Treating cells with lysosomotropic drugs causes the recruitment of LRRK2 and its substrate Rab10 onto overloaded lysosomes and induces extracellular release of lysosomal contents. Here we show that lysosomal overload elicits the release of insoluble α-synuclein from macrophages and microglia loaded with α-synuclein fibrils.

The V-ATPase-ATG16L1 axis recruits LRRK2 to facilitate the lysosomal stress response.

Leucine-rich repeat kinase 2 (LRRK2), a Rab kinase associated with Parkinson's disease and several inflammatory diseases, has been shown to localize to stressed lysosomes and get activated to regulate lysosomal homeostasis. However, the mechanisms of LRRK2 recruitment and activation have not been well understood. Here, we found that the ATG8 conjugation system regulates the recruitment of LRRK2 as well as LC3 onto single membranes of stressed lysosomes/phagosomes.

Phosphorylation of Rab29 at Ser185 regulates its localization and role in the lysosomal stress response in concert with LRRK2.

Rab proteins are small GTPases that regulate a myriad of intracellular membrane trafficking events. Rab29 is one of the Rab proteins phosphorylated by leucine-rich repeat kinase 2 (LRRK2), a Parkinson's disease-associated kinase. Recent studies suggest that Rab29 regulates LRRK2, whereas the mechanism by which Rab29 is regulated remained unclear.

Two Methods to Analyze LRRK2 Functions Under Lysosomal Stress: The Measurements of Cathepsin Release and Lysosomal Enlargement.

Leucine-rich repeat kinase 2 (LRRK2) is a causative gene product of autosomal-dominant Parkinson's disease and has been shown to play a role in lysosomal regulation. We have previously shown that endogenous LRRK2 recruited its substrates Rab8a and Rab10 onto overloaded lysosomes depending on their phosphorylation, which functioned in the suppression of lysosomal enlargement as well as the promotion of the exocytic release of lysosomal cathepsins. In this chapter, we introduce two methods to analyze cellular functions of LRRK2 upon exposure to lysosomal overload stress in RAW264.

Roles of lysosomotropic agents on LRRK2 activation and Rab10 phosphorylation.

Leucine-rich repeat kinase 2 (LRRK2), the major causative gene product of autosomal-dominant Parkinson's disease, is a protein kinase that phosphorylates a subset of Rab GTPases. Since pathogenic LRRK2 mutations increase its ability to phosphorylate Rab GTPases, elucidating the mechanisms of how Rab phosphorylation is regulated by LRRK2 is of great importance. We have previously reported that chloroquine-induced lysosomal stress facilitates LRRK2 phosphorylation of Rab10 to maintain lysosomal homeostasis.

LRRK2 and its substrate Rab GTPases are sequentially targeted onto stressed lysosomes and maintain their homeostasis.

Leucine-rich repeat kinase 2 () has been associated with a variety of human diseases, including Parkinson's disease and Crohn's disease, whereas deficiency leads to accumulation of abnormal lysosomes in aged animals. However, the cellular roles and mechanisms of LRRK2-mediated lysosomal regulation have remained elusive. Here, we reveal a mechanism of stress-induced lysosomal response by LRRK2 and its target Rab GTPases.

Parkinson's disease-associated mutant LRRK2 phosphorylates Rab7L1 and modifies trans-Golgi morphology.

Mutations in leucine-rich repeat kinase 2 (LRRK2) are the major genetic cause of autosomal-dominantly inherited Parkinson's disease. LRRK2 is implicated in the regulation of intracellular trafficking, neurite outgrowth and PD risk in connection with Rab7L1, a putative interactor of LRRK2. Recently, a subset of Rab GTPases have been reported as substrates of LRRK2.