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LRRK2 impairs PINK1/Parkin-dependent mitophagy via its kinase activity: pathologic insights into Parkinson's disease
Fiona Bonello1,2,3,4, Sidi-Mohamed Hassoun1,2,3,4, François Mouton-Liger1,2,3,4
1Institut du Cerveau et de la Moelle épinière, ICM, Paris, France.
Abstract:
Mutations of LRRK2, encoding leucine-rich repeat kinase 2 (LRRK2), are the leading cause of autosomal dominant Parkinson's disease (PD). The most frequent of these mutations, G2019S substitution, increases kinase activity, but it remains unclear how it causes PD. Recent studies suggest that LRRK2 modulates mitochondrial homeostasis. Mitochondrial dysfunction plays a key role in the pathogenesis of autosomal recessive PD forms linked to PARK2 and PINK1, encoding the cytosolic E3 ubiquitin-protein ligase Parkin and the mitochondrial kinase PINK1, which jointly regulate mitophagy. We explored the role of LRRK2 and its kinase activity in PINK1/Parkin-dependent mitophagy. LRRK2 increased mitochondrial aggregation and attenuated mitochondrial clearance in cells coexpressing Parkin and exposed to the protonophore carbonylcyanide m-chlorophenylhydrazone. Förster resonance energy transfer imaging microscopy showed that LRRK2 impaired the interactions between Parkin and Drp1 and their mitochondrial targets early in mitophagy. The inhibition of LRRK2 kinase activity by a 'kinase-dead' LRRK2 mutation or with a pharmacological inhibitor (LRRK2-IN-1) restored these interactions. The monitoring of mitophagy in human primary fibroblasts with the novel dual-fluorescence mtRosella reporter and a new hypothermic shock paradigm revealed similar defects in PD patients with the G2019S LRRK2 substitution or PARK2 mutations relative to healthy subjects. This defect was restored by LRRK2-IN-1 treatment in LRRK2 patients only. Our results suggest that PD forms due to LRRK2 and PARK2 mutations involve pathogenic mechanisms converging on PINK1/Parkin-dependent mitophagy.
Insights
Mutations in leucine-rich repeat kinase 2 (LRRK2) cause Parkinson's disease by impairing mitophagy, the process of clearing damaged mitochondria. Inhibiting LRRK2 kinase activity restored this essential cellular function in patient cells.
Area of Science:
- Neuroscience
- Cell Biology
- Genetics
Background:
- Mutations in leucine-rich repeat kinase 2 (LRRK2) are a primary cause of autosomal dominant Parkinson's disease (PD).
- Mitochondrial dysfunction is implicated in Parkinson's pathogenesis, particularly in forms linked to PARK2 and PINK1, which regulate mitophagy.
- The precise mechanism by which LRRK2 mutations cause PD, especially concerning mitochondrial health, remains incompletely understood.
Purpose of the Study:
- To investigate the role of LRRK2 and its kinase activity in PINK1/Parkin-dependent mitophagy.
- To determine if LRRK2 mutations converge with PARK2 mutations in affecting mitophagy pathways.
- To assess the therapeutic potential of inhibiting LRRK2 kinase activity on mitophagy defects.
Main Methods:
- Utilized Förster resonance energy transfer (FRET) imaging microscopy to analyze protein interactions during mitophagy.
- Employed a dual-fluorescence mtRosella reporter and a hypothermic shock paradigm in human primary fibroblasts.
- Assessed the impact of LRRK2 kinase activity inhibition using a 'kinase-dead' mutant and a pharmacological inhibitor (LRRK2-IN-1).
Main Results:
- LRRK2 expression led to increased mitochondrial aggregation and reduced clearance, impairing mitophagy.
- LRRK2 was found to disrupt early interactions between Parkin, Drp1, and their mitochondrial targets.
- Pharmacological inhibition of LRRK2 kinase activity restored these interactions and mitophagy.
- Fibroblasts from PD patients with LRRK2 G2019S or PARK2 mutations exhibited mitophagy defects, which were ameliorated by LRRK2-IN-1 in LRRK2 patients.
Conclusions:
- PD-associated LRRK2 mutations impair PINK1/Parkin-dependent mitophagy, contributing to disease pathogenesis.
- Pathogenic mechanisms in LRRK2 and PARK2-linked PD converge on mitophagy.
- Inhibiting LRRK2 kinase activity represents a potential therapeutic strategy for LRRK2-related Parkinson's disease.