# Membrane Dysfunction as a Central Mechanism in LRRK2-Associated Parkinson’s Disease: Comparative Analysis of G2019S and I1371V Variants

## TL;DR

This study shows that a specific LRRK2 mutation causes severe membrane problems in Parkinson’s disease, and different mutations respond to different treatments.

## Contribution

The study reveals that GTPase domain LRRK2 mutations cause distinct membrane lipid dysregulation and require variant-specific therapies.

## Key findings

- The I1371V LRRK2 mutation causes severe membrane cholesterol depletion and disrupted lipid microdomains.
- I1371V-expressing cells show impaired dopamine transporter function and altered membrane topology.
- Non-selective LRRK2 modulators are more effective than kinase-selective inhibitors for I1371V-related defects.

## Abstract

What are the main findings?

GTPase domain LRRK2 mutation (I1371V) drives severe membrane lipid dysregulation:
The I1371V mutation induces enhanced LRRK2 autophosphorylation and Rab8A and Rab10 hyperphosphorylation, leading to impaired sterol trafficking, selective membrane cholesterol depletion, increased membrane fluidity, disrupted lipid microdomains, altered membrane topology, and consequent defects in dopamine transporter localization and dopamine uptake—effects that are substantially milder in the kinase domain G2019S mutation.
LRRK2 mutation-specific pharmacological responses reveal mechanistic heterogeneity:
Membrane and dopaminergic defects caused by the I1371V mutation are preferentially rescued by a non-selective LRRK2 modulator (GW5074) rather than a kinase-selective inhibitor (MLi-2), demonstrating that GTPase domain-driven pathology depends on broader LRRK2 regulatory mechanisms and highlighting the need for variant-specific therapeutic strategies.

GTPase domain LRRK2 mutation (I1371V) drives severe membrane lipid dysregulation:

The I1371V mutation induces enhanced LRRK2 autophosphorylation and Rab8A and Rab10 hyperphosphorylation, leading to impaired sterol trafficking, selective membrane cholesterol depletion, increased membrane fluidity, disrupted lipid microdomains, altered membrane topology, and consequent defects in dopamine transporter localization and dopamine uptake—effects that are substantially milder in the kinase domain G2019S mutation.

LRRK2 mutation-specific pharmacological responses reveal mechanistic heterogeneity:

Membrane and dopaminergic defects caused by the I1371V mutation are preferentially rescued by a non-selective LRRK2 modulator (GW5074) rather than a kinase-selective inhibitor (MLi-2), demonstrating that GTPase domain-driven pathology depends on broader LRRK2 regulatory mechanisms and highlighting the need for variant-specific therapeutic strategies.

What are the implications of the main findings?
Membrane lipid dysregulation emerges as a core cell biological
mechanism in LRRK2-associated PD, particularly for GTPase domain mutations,
linking aberrant Rab phosphorylation to sterol trafficking defects, membrane
disorganization, and impaired dopaminergic function.Therapeutic strategies for LRRK2-PD must be mutation-specific, as
GTPase domain variants respond preferentially to broader LRRK2 modulation
rather than kinase-selective inhibition, underscoring the need for precision
targeting based on domain-specific pathogenic mechanisms.

Membrane lipid dysregulation emerges as a core cell biological
mechanism in LRRK2-associated PD, particularly for GTPase domain mutations,
linking aberrant Rab phosphorylation to sterol trafficking defects, membrane
disorganization, and impaired dopaminergic function.

Therapeutic strategies for LRRK2-PD must be mutation-specific, as
GTPase domain variants respond preferentially to broader LRRK2 modulation
rather than kinase-selective inhibition, underscoring the need for precision
targeting based on domain-specific pathogenic mechanisms.

Mutations in leucine-rich repeat kinase 2 (LRRK2) are among the most common genetic causes of Parkinson’s disease (PD), yet substantial heterogeneity exists among pathogenic variants. How mutations in distinct functional domains of LRRK2 differentially perturb cellular homeostasis remains incompletely understood. Here, we compared two pathogenic LRRK2 mutations—G2019S in the kinase domain and I1371V in the GTPase domain—across multiple cellular models, including SH-SY5Y and U87 cells, and healthy human iPSC-derived floor plate cells. We demonstrate that the I1371V mutation induces markedly more severe cellular dysfunction than G2019S. I1371V-expressing cells exhibited elevated LRRK2 autophosphorylation at S1292 and robust hyperphosphorylation of Rab8A and Rab10, indicating enhanced downstream signaling. These alterations impaired sterol trafficking, leading to selective depletion of membrane cholesterol without changes in total cellular cholesterol. Consequently, I1371V cells displayed increased membrane fluidity, disrupted microdomain organization, altered membrane topology, reduced caveolin-1 expression, and impaired dopamine transporter surface expression and dopamine uptake. Lipidomic profiling further revealed a broad disruption of lipid homeostasis, including reductions in cholesteryl esters, sterols, sphingolipids, and glycerophospholipids, whereas G2019S cells showed comparatively modest changes. Pharmacological intervention revealed mutation-specific responses, with the non-selective LRRK2 modulator GW5074 outperforming the kinase-selective inhibitor MLi-2 in restoring Rab8A phosphorylation, membrane integrity, and dopaminergic function. Collectively, these findings identify membrane lipid dysregulation as a central cell biological mechanism in LRRK2-associated PD and underscore the importance of variant-specific therapeutic strategies.