Objective: This study investigates the impact of LRRK2 I1371V mutation on astrocyte plasma membrane dynamics & its association with extracellular α-synuclein using astrocytes derived from PD LRRK2 I1371V iPSCs. Additionally, the pathophysiological effects of extracellular α-synuclein on both healthy control (HC) & PD astrocytes were examined.

Background: Missense mutations in LRRK2, commonly linked to familial PD, exhibit ethnic diversity & distinct treatment responses. While G2019S is well-studied in Caucasians, I1371V is more prevalent in East Asia. These mutations differ in disease onset, severity, progression, response to therapies like DBS & presence of Lewy bodies. Given the crucial role of astrocytes in dopaminergic neuron survival & post-mortem detection of Lewy bodies in I1371V carriers, it is essential to examine how extracellular α-synuclein influences niche cells in this context.

Method: PD LRRK2 I1371V iPSC-derived astrocytes & LRRK2 I1371V-transfected U87 cells were analyzed. α-Synuclein (monomeric & aggregated) association with cells was assessed via confocal imaging & FACS. Membrane fluidity, GM1 expression, & lipid raft marker Caveolin1 were measured. Membrane topology was evaluated using AFM, while total & membrane cholesterol were quantified. Amyloid pore formation was examined via live-cell calcium imaging, & Rab8A/Rab10 phosphorylation measured using FACS & immunofluorescence.

Results: PD astrocytes exhibited reduced α-synuclein association & uptake, likely due to altered membrane cholesterol, fluidity & ganglioside expression. Microdomains were significantly lesser in LRRK2 I1371V astrocytes & resembled cholesterol depleted HC astrocytes. Increased Rab8A & Rab10 phosphorylation, linked to LRRK2 I1371V mutation, contributed to these changes. Despite no significant impact on cell viability, PD astrocytes displayed heightened ROS, RNS, & pro-inflammatory cytokines (IL-6, IL-1β, TNF-α). Aggregated α-synuclein triggered elevated Ca²⁺ influx, increasing oxidative stress & inflammation. This was associated with enhanced α-synuclein phosphorylation(Ser129) & nitration(Tyr125).

Conclusion: The LRRK2 I1371V mutation alters astrocyte membrane properties, reducing α-synuclein uptake & amplifying oxidative stress, which exacerbates α-synuclein pathology through increased Ca²⁺ influx, ROS/RNS production, & α-synuclein modifications.

Association aSyn with astrocytes

Membrane Topology through AFM

Intracellular Ca2+ rise upon aSyn addition

Increased pSyn-129 & nSyn in LRRK2 astrocytes

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MDS Abstracts - https://www.mdsabstracts.org/abstract/alterations-of-plasma-membrane-in-parkinsons-disease-lrrk2-i1371v-ipsc-derived-astrocytes-contribute-to-the-vulnerability-of-the-niche-cells-to-extracellular-%ce%b1-synuclein/