Axonal Lysosomal Assays for Characterizing the Effects of LRRK2 G2019S

Area of Science:

• Neuroscience
• Cell Biology
• Genetics

Background:

• Parkinson's disease (PD) is characterized by axonal "dying back" degeneration.
• Early pathogenesis and therapeutic targets for PD require robust axonal models.
• Lysosomal trafficking and injury repair defects are hypothesized contributors to PD axonal pathology.

Purpose of the Study:

• To develop and validate assays for quantifying axonal trafficking and injury repair in Parkinson's disease models.
• To investigate the role of LRRK2 G2019S mutations in axonal lysosomal dysfunction and repair.
• To establish a platform for identifying potential therapeutics for PD-related axonal degeneration.

Main Methods:

• Utilized induced pluripotent stem cell (iPSC)-derived neurons from patients with LRRK2 G2019S mutations and isogenic controls.
• Developed quantitative assays to measure axonal lysosomal trafficking and response to injury (axotomy).
• Assessed Rab10 phosphorylation and lysosomal markers in response to mutant LRRK2 expression and injury.

Main Results:

• Observed subtle axonal trafficking defects in LRRK2 G2019S mutant neurons, partially rescued by a LRRK2 inhibitor.
• Identified increased phosphorylated Rab10-positive lysosomes and enhanced LRRK2-dependent Rab10 phosphorylation upon lysosomal damage.
• Noted a transient increase in lysosomes at axotomy sites in mutant LRRK2 neurons, suggesting altered injury response.

Conclusions:

• Developed novel axonal lysosomal assays using iPSC-derived neurons for PD research.
• Demonstrated subtle but measurable axonal lysosomal trafficking and injury repair phenotypes associated with LRRK2 G2019S mutations.
• These assays show potential for characterizing early PD pathogenesis and screening therapeutic interventions for LRRK2-related PD.