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Hum Mol Genet. 2018 Jan 1;27(1):178-189. doi: 10.1093/hmg/ddx393.

Loss of CHCHD10-CHCHD2 complexes required for respiration underlies the pathogenicity of a CHCHD10 mutation in ALS.

Author information

1
Department of Human Genetics, McGill University, Montreal, QC H3A 2B4, Canada.
2
Montreal Neurological Institute, McGill University, Montreal, QC H3A 2B4, Canada.
3
Department of Biochemistry, Faculty of Medicine, Chiang Mai University, Chiang Mai, Lampang 52000, Thailand.
4
Sunnybrook Health Sciences Centre, Toronto, ON M4N 3M5, Canada.
5
Tanz Centre for Research in Neurodegenerative Diseases, University of Toronto, Toronto, ON M5T 2S8, Canada.

Abstract

Coiled-helix coiled-helix domain containing protein 10 (CHCHD10) and its paralogue CHCHD2 belong to a family of twin CX9C motif proteins, most of which localize to the intermembrane space of mitochondria. Dominant mutations in CHCHD10 cause amyotrophic lateral sclerosis (ALS)/frontotemporal dementia, and mutations in CHCHD2 have been associated with Parkinson's disease, but the function of these proteins remains unknown. Here we show that the p.R15L CHCHD10 variant in ALS patient fibroblasts destabilizes the protein, leading to a defect in the assembly of Complex I, impaired cellular respiration, mitochondrial hyperfusion, an increase in the steady-state level of CHCHD2, and a severe proliferation defect on galactose, a substrate that forces cells to synthesize virtually all of their ATP aerobically. CHCHD10 and CHCHD2 appeared together in distinct foci by immunofluorescence analysis and could be quantitatively immunoprecipitated with antibodies against either protein. Blue native polyacrylamide gel electrophoresis analyses showed that both proteins migrated in a high molecular weight complex (220 kDa) in control cells, which was, however, absent in patient cells. CHCHD10 and CHCHD2 levels increased markedly in control cells in galactose medium, a response that was dampened in patient cells, and a new complex (40 kDa) appeared in both control and patient cells cultured in galactose. Re-entry of patient cells into the cell cycle, which occurred after prolonged culture in galactose, was associated with a marked increase in Complex I, and restoration of the oxygen consumption defect. Our results indicate that CHCHD10-CHCHD2 complexes are necessary for efficient mitochondrial respiration, and support a role for mitochondrial dysfunction in some patients with ALS.

PMID:
29121267
PMCID:
PMC5886208
DOI:
10.1093/hmg/ddx393
[Indexed for MEDLINE]
Free PMC Article

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