Lrrk promotes tau neurotoxicity through dysregulation of actin and mitochondrial dynamics

Area of Science:

• Neuroscience
• Genetics
• Cell Biology

Background:

• Mutations in leucine-rich repeat kinase 2 (LRRK2) are a leading genetic cause of familial Parkinson disease.
• The molecular link between LRRK2 mutations, tau pathology, and Parkinson disease pathogenesis remains incompletely understood.
• Understanding these connections is crucial for developing effective Parkinson disease therapies.

Purpose of the Study:

• To investigate the functional interaction between LRRK2 and tau in Parkinson disease models.
• To elucidate the cellular and molecular mechanisms by which LRRK2 mutations influence tau neurotoxicity.
• To explore potential therapeutic strategies targeting LRRK2 and tau pathways.

Main Methods:

• Utilized Drosophila and mouse models of tauopathy to study LRRK2-tau interactions.
• Assessed the impact of altered Lrrk expression and Parkinson disease-associated mutations on tau neurotoxicity.
• Investigated cellular mechanisms involving filamentous actin (F-actin) stabilization and mitochondrial dynamics (Drp1 mislocalization).
• Performed biochemical assays to characterize LRRK2's actin-severing activity and oligomerization.

Main Results:

• Altering Lrrk levels in Drosophila models modulated tau neurotoxicity, with exacerbation by Parkinson disease-associated LRRK2 mutations.
• Changes in Lrrk expression led to F-actin stabilization and Drp1 mislocalization, contributing to tau-induced neurotoxicity.
• Biochemical analysis revealed that monomeric LRRK2 possesses actin-severing activity, which is diminished upon LRRK2 oligomerization.

Conclusions:

• LRRK2's interaction with tau provides a mechanistic basis for LRRK2-mediated Parkinson disease, potentially involving a dominant-negative effect.
• Findings suggest a shared molecular pathway between LRRK2 Parkinson disease and other familial forms linked to mitochondrial dysfunction.
• The study highlights LRRK2 and tau as potential therapeutic targets for Parkinson disease and related neurodegenerative disorders.