Fibrillar α-synuclein toxicity depends on functional lysosomes

Area of Science:

• Neuroscience
• Cell Biology
• Neurodegenerative Diseases

Background:

• Parkinson's disease (PD) neurodegeneration can be modeled using alpha-synuclein preformed fibrils (PFFs).
• The precise mechanism of PFF-induced neurotoxicity remains unclear.
• Iron's role in PD pathogenesis suggests investigating ferroptosis, an iron-dependent cell death pathway.

Purpose of the Study:

• To determine if alpha-synuclein PFFs induce ferroptosis in neuronal cells.
• To elucidate the mechanism of alpha-synuclein PFF toxicity.
• To explore potential therapeutic targets for PD.

Main Methods:

• Neuronal cell lines and primary cortical neurons were treated with alpha-synuclein PFFs.
• Various ferroptosis inhibitors, including liproxstatin-1, were used to assess cell viability.
• Autophagy and lysosomal pathway inhibitors (chloroquine, bafilomycin A1, leupeptin, E-64D, Ca-074-Me) were employed.
• Immunofluorescence microscopy was used to track PFF uptake and lysosomal localization.

Main Results:

• Ferroptosis inhibitors generally failed to rescue cell viability, except for high-dose liproxstatin-1.
• High-dose liproxstatin-1 induced lysosomal changes, suggesting an indirect effect.
• Alpha-synuclein PFF-induced toxicity was attenuated by lysosomal inhibitors, indicating a role for functional lysosomes.
• Heparin blocked PFF uptake, while chloroquine inhibited toxicity by impairing lysosomal function, not blocking uptake.

Conclusions:

• Alpha-synuclein PFFs exert toxicity within functional lysosomes, not through ferroptosis.
• Lysosomal pathways are critical mediators of alpha-synuclein PFF toxicity in neurons.
• Strategies aimed at preventing alpha-synuclein fibril uptake into lysosomes may be a promising therapeutic avenue for Parkinson's disease.