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Dis Model Mech. 2020 Jan 17;13(1). pii: dmm040899. doi: 10.1242/dmm.040899.

Misfolded α-synuclein causes hyperactive respiration without functional deficit in live neuroblastoma cells.

Author information

1
Department of Biochemistry and Genetics, La Trobe University, Bundoora, VIC 3086, Australia.
2
Department of Microbiology and Immunology, University of Melbourne, Parkville, VIC 3052, Australia.
3
Howard Florey Institute of Neuroscience and Mental Health, Parkville, VIC 3052, Australia.
4
Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, VIC 3052, Australia.
5
Department of Physiology, Anatomy and Microbiology, La Trobe University, Bundoora, VIC 3086, Australia.
6
La Trobe University-Comprehensive Proteomics Platform, La Trobe University, Bundoora, VIC 3086, Australia.
7
Department of Biochemistry and Genetics, La Trobe University, Bundoora, VIC 3086, Australia andrew.hill@latrobe.edu.au.

Abstract

The misfolding and aggregation of the largely disordered protein, α-synuclein, is a central pathogenic event that occurs in the synucleinopathies, a group of neurodegenerative disorders that includes Parkinson's disease. While there is a clear link between protein misfolding and neuronal vulnerability, the precise pathogenic mechanisms employed by disease-associated α-synuclein are unresolved. Here, we studied the pathogenicity of misfolded α-synuclein produced using the protein misfolding cyclic amplification (PMCA) assay. To do this, previous published methods were adapted to allow PMCA-induced protein fibrillization to occur under non-toxic conditions. Insight into potential intracellular targets of misfolded α-synuclein was obtained using an unbiased lipid screen of 15 biologically relevant lipids that identified cardiolipin (CA) as a potential binding partner for PMCA-generated misfolded α-synuclein. To investigate whether such an interaction can impact the properties of α-synuclein misfolding, protein fibrillization was carried out in the presence of the lipid. We show that CA both accelerates the rate of α-synuclein fibrillization and produces species that harbour enhanced resistance to proteolysis. Because CA is virtually exclusively expressed in the inner mitochondrial membrane, we then assessed the ability of these misfolded species to alter mitochondrial respiration in live non-transgenic SH-SY5Y neuroblastoma cells. Extensive analysis revealed that misfolded α-synuclein causes hyperactive mitochondrial respiration without causing any functional deficit. These data give strong support for the mitochondrion as a target for misfolded α-synuclein and reveal persistent, hyperactive respiration as a potential upstream pathogenic event associated with the synucleinopathies.This article has an associated First Person interview with the first author of the paper.

KEYWORDS:

Cardiolipin; Mitochondria; PMCA; Parkinson's disease; Synucleinopathy; α-Synuclein

PMID:
31848207
DOI:
10.1242/dmm.040899
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Conflict of interest statement

Competing interestsThe authors declare no competing or financial interests.

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