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Mitochondrial permeability transition pore: sensitivity to opening and mechanistic dependence on substrate availability

Briston, T; Roberts, M; Lewis, S; Powney, B; M Staddon, J; Szabadkai, G; Duchen, MR; (2017) Mitochondrial permeability transition pore: sensitivity to opening and mechanistic dependence on substrate availability. Scientific Reports , 7 , Article 10492. 10.1038/s41598-017-10673-8. Green open access

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Abstract

Mitochondrial Ca(2+) uptake has a key role in cellular Ca(2+) homeostasis. Excessive matrix Ca(2+) concentrations, especially when coincident with oxidative stress, precipitate opening of an inner mitochondrial membrane, high-conductance channel: the mitochondrial permeability transition pore (mPTP). mPTP opening has been implicated as a final cell death pathway in numerous diseases and therefore understanding conditions dictating mPTP opening is crucial for developing targeted therapies. Here, we have investigated the impact of mitochondrial metabolic state on the probability and consequences of mPTP opening. Isolated mitochondria were energised using NADH- or FADH2-linked substrates. The functional consequences of Ca(2+)-induced mPTP opening were assessed by Ca(2+) retention capacity, using fluorescence-based analysis, and simultaneous measurements of mitochondrial Ca(2+) handling, membrane potential, respiratory rate and production of reactive oxygen species (ROS). Succinate-induced, membrane potential-dependent reverse electron transfer sensitised mitochondria to mPTP opening. mPTP-induced depolarisation under succinate subsequently inhibited reverse electron transfer. Complex I-driven respiration was reduced after mPTP opening but sustained in the presence of complex II-linked substrates, consistent with inhibition of complex I-supported respiration by leakage of matrix NADH. Additionally, ROS generated at complex III did not sensitise mitochondria to mPTP opening. Thus, cellular metabolic fluxes and metabolic environment dictate mitochondrial functional response to Ca(2+) overload.

Type: Article
Title: Mitochondrial permeability transition pore: sensitivity to opening and mechanistic dependence on substrate availability
Location: England
Open access status: An open access version is available from UCL Discovery
DOI: 10.1038/s41598-017-10673-8
Publisher version: http://doi.org/10.1038/s41598-017-10673-8
Additional information: Copyright © The Author(s) 2017. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. Te images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.
UCL classification: 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: http://discovery.ucl.ac.uk/id/eprint/1573189
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