1. Fibrillar α-synuclein toxicity depends on functional lysosomes
- Author
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David Finkelstein, Paul A. Adlard, Scott Ayton, Peng Lei, Stephanie J. Guiney, Celeste H. Mawal, and Ashley I. Bush
- Subjects
0301 basic medicine ,Programmed cell death ,Endosomes ,Protein degradation ,Biochemistry ,Cathepsin B ,03 medical and health sciences ,chemistry.chemical_compound ,Neurobiology ,Lysosome ,medicine ,Animals ,Ferroptosis ,Humans ,Viability assay ,Molecular Biology ,Cells, Cultured ,Mice, Knockout ,030102 biochemistry & molecular biology ,Chemistry ,Dopaminergic Neurons ,Neurodegeneration ,Leupeptin ,Bafilomycin ,Parkinson Disease ,Cell Biology ,medicine.disease ,Cell biology ,Mice, Inbred C57BL ,030104 developmental biology ,medicine.anatomical_structure ,nervous system ,alpha-Synuclein ,Lysosomes - Abstract
Neurodegeneration in Parkinson's disease (PD) can be recapitulated in animals by administration of α-synuclein preformed fibrils (PFFs) into the brain. However, the mechanism by which these PFFs induce toxicity is unknown. Iron is implicated in PD pathophysiology, so we investigated whether α-synuclein PFFs induce ferroptosis, an iron-dependent cell death pathway. A range of ferroptosis inhibitors were added to a striatal neuron-derived cell line (STHdhQ7/7 cells), a dopaminergic neuron-derived cell line (SN4741 cells), and WT primary cortical neurons, all of which had been intoxicated with α-synuclein PFFs. Viability was not recovered by these inhibitors except for liproxstatin-1, a best-in-class ferroptosis inhibitor, when used at high doses. High-dose liproxstatin-1 visibly enlarged the area of a cell that contained acidic vesicles and elevated the expression of several proteins associated with the autophagy-lysosomal pathway similarly to the known lysosomal inhibitors, chloroquine and bafilomycin A1. Consistent with high-dose liproxstatin-1 protecting via a lysosomal mechanism, we further de-monstrated that loss of viability induced by α-synuclein PFFs was attenuated by chloroquine and bafilomycin A1 as well as the lysosomal cysteine protease inhibitors, leupeptin, E-64D, and Ca-074-Me, but not other autophagy or lysosomal enzyme inhibitors. We confirmed using immunofluorescence microscopy that heparin prevented uptake of α-synuclein PFFs into cells but that chloroquine did not stop α-synuclein uptake into lysosomes despite impairing lysosomal function and inhibiting α-synuclein toxicity. Together, these data suggested that α-synuclein PFFs are toxic in functional lysosomes in vitro. Therapeutic strategies that prevent α-synuclein fibril uptake into lysosomes may be of benefit in PD.
- Published
- 2020