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

Cathryn L. Ugalde; Sarah J. Annesley; Shane E. Gordon; Katelyn Mroczek; Matthew A. Perugini; Victoria A. Lawson; Paul R. Fisher; David I. Finkelstein; Andrew F. Hill

doi:10.1242/dmm.040899

Disease Models & Mechanisms (Jan 2020)

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

Cathryn L. Ugalde,
Sarah J. Annesley,
Shane E. Gordon,
Katelyn Mroczek,
Matthew A. Perugini,
Victoria A. Lawson,
Paul R. Fisher,
David I. Finkelstein,
Andrew F. Hill

Affiliations

Cathryn L. Ugalde: Department of Biochemistry and Genetics, La Trobe University, Bundoora, VIC 3086, Australia
Sarah J. Annesley: Department of Physiology, Anatomy and Microbiology, La Trobe University, Bundoora, VIC 3086, Australia
Shane E. Gordon: Department of Biochemistry and Genetics, La Trobe University, Bundoora, VIC 3086, Australia
Katelyn Mroczek: Department of Physiology, Anatomy and Microbiology, La Trobe University, Bundoora, VIC 3086, Australia
Matthew A. Perugini: Department of Biochemistry and Genetics, La Trobe University, Bundoora, VIC 3086, Australia
Victoria A. Lawson: Department of Microbiology and Immunology, University of Melbourne, Parkville, VIC 3052, Australia
Paul R. Fisher: Department of Physiology, Anatomy and Microbiology, La Trobe University, Bundoora, VIC 3086, Australia
David I. Finkelstein: Howard Florey Institute of Neuroscience and Mental Health, Parkville, VIC 3052, Australia
Andrew F. Hill: Department of Biochemistry and Genetics, La Trobe University, Bundoora, VIC 3086, Australia

DOI: https://doi.org/10.1242/dmm.040899
Journal volume & issue: Vol. 13, no. 1

Abstract

Read online

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.

Published in Disease Models & Mechanisms

ISSN: 1754-8403 (Print); 1754-8411 (Online)
Publisher: The Company of Biologists
Country of publisher: United Kingdom
LCC subjects: Medicine: Pathology
Website: https://journals.biologists.com/dmm

About the journal

Abstract

Keywords