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Impaired Cellular Bioenergetics Causes Mitochondrial Calcium Handling Defects in MT-ND5 Mutant Cybrids

McKenzie, M; Duchen, MR; (2016) Impaired Cellular Bioenergetics Causes Mitochondrial Calcium Handling Defects in MT-ND5 Mutant Cybrids. PLOS One , 11 (4) , Article e0154371. 10.1371/journal.pone.0154371. Green open access

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Abstract

Mutations in mitochondrial DNA (mtDNA) can cause mitochondrial disease, a group of metabolic disorders that affect both children and adults. Interestingly, individual mtDNA mutations can cause very different clinical symptoms, however the factors that determine these phenotypes remain obscure. Defects in mitochondrial oxidative phosphorylation can disrupt cell signaling pathways, which may shape these disease phenotypes. In particular, mitochondria participate closely in cellular calcium signaling, with profound impact on cell function. Here, we examined the effects of a homoplasmic m.13565C>T mutation in MT-ND5 on cellular calcium handling using transmitochondrial cybrids (ND5 mutant cybrids). We found that the oxidation of NADH and mitochondrial membrane potential (Δψm) were significantly reduced in ND5 mutant cybrids. These metabolic defects were associated with a significant decrease in calcium uptake by ND5 mutant mitochondria in response to a calcium transient. Inhibition of glycolysis with 2-deoxy-D-glucose did not affect cytosolic calcium levels in control cybrids, but caused an increase in cytosolic calcium in ND5 mutant cybrids. This suggests that glycolytically-generated ATP is required not only to maintain Δψm in ND5 mutant mitochondria but is also critical for regulating cellular calcium homeostasis. We conclude that the m.13565C>T mutation in MT-ND5 causes defects in both mitochondrial oxidative metabolism and mitochondrial calcium sequestration. This disruption of mitochondrial calcium handling, which leads to defects in cellular calcium homeostasis, may be an important contributor to mitochondrial disease pathogenesis.

Type: Article
Title: Impaired Cellular Bioenergetics Causes Mitochondrial Calcium Handling Defects in MT-ND5 Mutant Cybrids
Location: United States
Identifier: 10.1371/journal.pone.0154371
Open access status: An open access version is available from UCL Discovery
DOI: 10.1371/journal.pone.0154371
Additional information: © 2016 McKenzie, Duchen. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
UCL classification: UCL
UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Life Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Life Sciences > Div of Biosciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Life Sciences > Div of Biosciences > Cell and Developmental Biology
URI: https://discovery.ucl.ac.uk/id/eprint/1490308
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