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Kinnart I, Manders L, Heyninck T, Imberechts D, Praschberger R, Schoovaerts N, Verfaillie C, Verstreken P, Vandenberghe W. Elevated α-synuclein levels inhibit mitophagic flux. NPJ Parkinsons Dis 2024; 10:80. [PMID: 38594264 PMCID: PMC11004019 DOI: 10.1038/s41531-024-00696-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Accepted: 03/26/2024] [Indexed: 04/11/2024] Open
Abstract
The pathogenic effect of SNCA gene multiplications indicates that elevation of wild-type α-synuclein levels is sufficient to cause Parkinson's disease (PD). Mitochondria have been proposed to be a major target of α-synuclein-induced damage. PINK1/parkin/DJ-1-mediated mitophagy is a defense strategy that allows cells to selectively eliminate severely damaged mitochondria. Here, we quantified mitophagic flux and non-mitochondrial autophagic flux in three models of increased α-synuclein expression: 1/Drosophila melanogaster that transgenically express human wild-type and mutant α-synuclein in flight muscle; 2/human skin fibroblasts transfected with α-synuclein or β-synuclein; and 3/human induced pluripotent stem cell (iPSC)-derived neurons carrying an extra copy of wild-type SNCA under control of a doxycycline-inducible promoter, allowing titratable α-synuclein upregulation. In each model, elevated α-synuclein levels potently suppressed mitophagic flux, while non-mitochondrial autophagy was preserved. In human neurons, a twofold increase in wild-type α-synuclein was already sufficient to induce this effect. PINK1 and parkin activation and mitochondrial translocation of DJ-1 after mitochondrial depolarization were not affected by α-synuclein upregulation. Overexpression of the actin-severing protein cofilin or treatment with CK666, an inhibitor of the actin-related protein 2/3 (Arp2/3) complex, rescued mitophagy in neurons with increased α-synuclein, suggesting that excessive actin network stabilization mediated the mitophagy defect. In conclusion, elevated α-synuclein levels inhibit mitophagic flux. Disruption of actin dynamics may play a key role in this effect.
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Affiliation(s)
- Inge Kinnart
- Department of Neurosciences, Laboratory for Parkinson Research, KU Leuven, Leuven, Belgium
| | - Liselot Manders
- Department of Neurosciences, Laboratory for Parkinson Research, KU Leuven, Leuven, Belgium
| | - Thibaut Heyninck
- Department of Neurosciences, Laboratory for Parkinson Research, KU Leuven, Leuven, Belgium
| | - Dorien Imberechts
- Department of Neurosciences, Laboratory for Parkinson Research, KU Leuven, Leuven, Belgium
| | - Roman Praschberger
- Department of Neurosciences, Laboratory for Neuronal Communication, KU Leuven, Leuven, Belgium
- VIB-KU Leuven Center for Brain & Disease Research, Leuven, Belgium
| | - Nils Schoovaerts
- Department of Neurosciences, Laboratory for Neuronal Communication, KU Leuven, Leuven, Belgium
- VIB-KU Leuven Center for Brain & Disease Research, Leuven, Belgium
| | | | - Patrik Verstreken
- Department of Neurosciences, Laboratory for Neuronal Communication, KU Leuven, Leuven, Belgium
- VIB-KU Leuven Center for Brain & Disease Research, Leuven, Belgium
| | - Wim Vandenberghe
- Department of Neurosciences, Laboratory for Parkinson Research, KU Leuven, Leuven, Belgium.
- Department of Neurology, University Hospitals Leuven, Leuven, Belgium.
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