Open AccessAlterations in voltage-sensing of the mitochondrial permeability transition pore in ANT1-deficient cells
Author(s) -
Judit Dóczi,
Beáta Törőcsik,
Andoni EchanizLaguna,
Bénédicte Mousson de Camaret,
Anatoly A. Starkov,
Natalia Starkova,
Anikó Gál,
Mária Judit Molnár,
Hibiki Kawamata,
Giovanni Manfredi,
Vera Ádám-Vizi,
Christos Chinopoulos
Publication year - 2016
Publication title -
scientific reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.24
H-Index - 213
ISSN - 2045-2322
DOI - 10.1038/srep26700
Subject(s) - mitochondrial permeability transition pore , calcein , mitochondrion , membrane potential , electrochemical gradient , inner mitochondrial membrane , biology , biophysics , mitochondrial membrane transport protein , microbiology and biotechnology , chemistry , biochemistry , apoptosis , membrane , programmed cell death
The probability of mitochondrial permeability transition (mPT) pore opening is inversely related to the magnitude of the proton electrochemical gradient. The module conferring sensitivity of the pore to this gradient has not been identified. We investigated mPT’s voltage-sensing properties elicited by calcimycin or H 2 O 2 in human fibroblasts exhibiting partial or complete lack of ANT1 and in C2C12 myotubes with knocked-down ANT1 expression. mPT onset was assessed by measuring in situ mitochondrial volume using the ‘thinness ratio’ and the ‘cobalt-calcein’ technique. De-energization hastened calcimycin-induced swelling in control and partially-expressing ANT1 fibroblasts, but not in cells lacking ANT1, despite greater losses of mitochondrial membrane potential. Matrix Ca 2+ levels measured by X-rhod-1 or mitochondrially-targeted ratiometric biosensor 4mtD3cpv, or ADP-ATP exchange rates did not differ among cell types. ANT1-null fibroblasts were also resistant to H 2 O 2 -induced mitochondrial swelling. Permeabilized C2C12 myotubes with knocked-down ANT1 exhibited higher calcium uptake capacity and voltage-thresholds of mPT opening inferred from cytochrome c release, but intact cells showed no differences in calcimycin-induced onset of mPT, irrespective of energization and ANT1 expression, albeit the number of cells undergoing mPT increased less significantly upon chemically-induced hypoxia than control cells. We conclude that ANT1 confers sensitivity of the pore to the electrochemical gradient.