Pathological structural conversion of α-synuclein at the mitochondria induces neuronal toxicity

• Published in: Nature neuroscience 2022-09, Vol.25 (9), p.1134-1148
• Main Authors: Choi, Minee L., Chappard, Alexandre, Singh, Bhanu P., Maclachlan, Catherine, Rodrigues, Margarida, Fedotova, Evgeniya I., Berezhnov, Alexey V., De, Suman, Peddie, Christopher J., Athauda, Dilan, Virdi, Gurvir S., Zhang, Weijia, Evans, James R., Wernick, Anna I., Zanjani, Zeinab Shadman, Angelova, Plamena R., Esteras, Noemi, Vinokurov, Andrey Y., Morris, Katie, Jeacock, Kiani, Tosatto, Laura, Little, Daniel, Gissen, Paul, Clarke, David J., Kunath, Tilo, Collinson, Lucy, Klenerman, David, Abramov, Andrey Y., Horrocks, Mathew H., Gandhi, Sonia
• Format: Article
• Language: English
• Subjects: 631/378/1689/1718; 631/57; 631/80/642/333; alpha-Synuclein - metabolism; Animal Genetics and Genomics; Behavioral Sciences; Biological Techniques; Biomedical and Life Sciences; Biomedicine; Biosensors; Cardiolipin; Cardiolipins - metabolism; Cell death; Conversion; Electron microscopy; Electron transport chain; Energy transfer; Fluorescence resonance energy transfer; Humans; Intracellular; Lipids; Membranes; Mitochondria; Mitochondria - metabolism; Mitochondrial Membranes - metabolism; Movement disorders; Mutation; Neurobiology; Neurodegenerative diseases; Neurons; Neurons - metabolism; Neurons - pathology; Neurosciences; Neurotoxicity; Oligomerization; Parkinson Disease - genetics; Parkinson Disease - metabolism; Parkinson's disease; Pluripotency; Protein seeding; Reactive oxygen species; Self-assembly; Stem cells; Synuclein; Toxicity
• ISSN: 1097-6256; 1546-1726
• DOI: 10.1038/s41593-022-01140-3

Aggregation of alpha-synuclein (α-Syn) drives Parkinson’s disease (PD), although the initial stages of self-assembly and structural conversion have not been directly observed inside neurons. In this study, we tracked the intracellular conformational states of α-Syn using a single-molecule Förster resonance energy transfer (smFRET) biosensor, and we show here that α-Syn converts from a monomeric state into two distinct oligomeric states in neurons in a concentration-dependent and sequence-specific manner. Three-dimensional FRET-correlative light and electron microscopy (FRET-CLEM) revealed that intracellular seeding events occur preferentially on membrane surfaces, especially at mitochondrial membranes. The mitochondrial lipid cardiolipin triggers rapid oligomerization of A53T α-Syn, and cardiolipin is sequestered within aggregating lipid–protein complexes. Mitochondrial aggregates impair complex I activity and increase mitochondrial reactive oxygen species (ROS) generation, which accelerates the oligomerization of A53T α-Syn and causes permeabilization of mitochondrial membranes and cell death. These processes were also observed in induced pluripotent stem cell (iPSC)–derived neurons harboring A53T mutations from patients with PD. Our study highlights a mechanism of de novo α-Syn oligomerization at mitochondrial membranes and subsequent neuronal toxicity. This study tracked the initial self-assembly, oligomerization and structural conversion of α-synuclein inside neurons. Early seeding events occur on mitochondrial membranes, where oligomerization induces mitochondrial dysfunction and neuronal loss.