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Hum Mol Genet. 2018 Jan 1;27(1):160-177. doi: 10.1093/hmg/ddx397.

In vitro and in vivo studies of the ALS-FTLD protein CHCHD10 reveal novel mitochondrial topology and protein interactions.

Author information

1
Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY 10065, USA.
2
Weill Cornell Graduate School of Medical Sciences, Weill Cornell Medicine, New York, NY 10065, USA.
3
Department of Neurology, Biochemistry and Molecular Biology, University of Miami Miller School of Medicine, Miami, FL 33136, USA.
4
The Jackson Laboratories, ME 04609, USA.
5
Harold and Margaret Milliken Hatch Laboratory of Neuroendocrinology, The Rockefeller University, New York, NY 10065, USA.
6
Division of Pulmonary and Critical Care Medicine, Joan and Sanford I. Weill Department of Medicine, Weill Cornell Medicine, New York, NY 10065, USA.

Abstract

Mutations in coiled-coil-helix-coiled-coil-helix-domain containing 10 (CHCHD10), a mitochondrial twin CX9C protein whose function is still unknown, cause myopathy, motor neuron disease, frontotemporal dementia, and Parkinson's disease. Here, we investigate CHCHD10 topology and its protein interactome, as well as the effects of CHCHD10 depletion or expression of disease-associated mutations in wild-type cells. We find that CHCHD10 associates with membranes in the mitochondrial intermembrane space, where it interacts with a closely related protein, CHCHD2. Furthermore, both CHCHD10 and CHCHD2 interact with p32/GC1QR, a protein with various intra and extra-mitochondrial functions. CHCHD10 and CHCHD2 have short half-lives, suggesting regulatory rather than structural functions. Cell lines with CHCHD10 knockdown do not display bioenergetic defects, but, unexpectedly, accumulate excessive intramitochondrial iron. In mice, CHCHD10 is expressed in many tissues, most abundantly in heart, skeletal muscle, liver, and in specific CNS regions, notably the dopaminergic neurons of the substantia nigra and spinal cord neurons, which is consistent with the pathology associated with CHCHD10 mutations. Homozygote CHCHD10 knockout mice are viable, have no gross phenotypes, no bioenergetic defects or ultrastructural mitochondrial abnormalities in brain, heart or skeletal muscle, indicating that functional redundancy or compensatory mechanisms for CHCHD10 loss occur in vivo. Instead, cells expressing S59L or R15L mutant versions of CHCHD10, but not WT, have impaired mitochondrial energy metabolism. Taken together, the evidence obtained from our in vitro and in vivo studies suggest that CHCHD10 mutants cause disease through a gain of toxic function mechanism, rather than a loss of function.

PMID:
29112723
PMCID:
PMC5886281
DOI:
10.1093/hmg/ddx397
[Indexed for MEDLINE]
Free PMC Article

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