title: Alterations in voltage-sensing of the mitochondrial permeability transition pore in ANT1-deficient cells.
abstract: 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 H2O2 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 H2O2-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.
authors.affiliation: Department of Medical Biochemistry, Semmelweis University MTA-SE Laboratory for Neurobiochemistry, Budapest, 1094, Hungary.|MTA-SE Lendület Neurobiochemistry Research Group, Budapest, Hungary.
authors.forename: Judit
authors.initials: J
authors.lastname: Doczi
authors.affiliation: Department of Medical Biochemistry, Semmelweis University MTA-SE Laboratory for Neurobiochemistry, Budapest, 1094, Hungary.
authors.forename: Beata
authors.initials: B
authors.lastname: Torocsik
authors.affiliation: Département de Neurologie, Hôpitaux Universitaires, Hôpital de Hautepierre, 67098 Strasbourg cedex, France.
authors.forename: Andoni
authors.initials: A
authors.lastname: Echaniz-Laguna
authors.affiliation: Service des Maladies Héréditaires du Métabolisme, Centre de Biologie et de Pathologie Est, CHU Lyon, 69677 Bron cedex, France.
authors.forename: Bénédicte
authors.initials: B
authors.lastname: Mousson de Camaret
authors.affiliation: Feil Family Brain and Mind Research Institute, Weill Cornell Medical College, New York, NY 10065, USA.
authors.forename: Anatoly
authors.initials: A
authors.lastname: Starkov
authors.affiliation: Icahn School of Medicine at Mount Sinai, Department of Hematology and Medical Oncology, New York, NY 10029, USA.
authors.forename: Natalia
authors.initials: N
authors.lastname: Starkova
authors.affiliation: Institute of Genomic Medicine and Rare Disorders, Semmelweis University, Budapest, 1083, Hungary.
authors.forename: Aniko
authors.initials: A
authors.lastname: Gál
authors.affiliation: Institute of Genomic Medicine and Rare Disorders, Semmelweis University, Budapest, 1083, Hungary.
authors.forename: Mária J
authors.initials: MJ
authors.lastname: Molnár
authors.affiliation: Feil Family Brain and Mind Research Institute, Weill Cornell Medical College, New York, NY 10065, USA.
authors.forename: Hibiki
authors.initials: H
authors.lastname: Kawamata
authors.affiliation: Feil Family Brain and Mind Research Institute, Weill Cornell Medical College, New York, NY 10065, USA.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Manfredi
authors.affiliation: Department of Medical Biochemistry, Semmelweis University MTA-SE Laboratory for Neurobiochemistry, Budapest, 1094, Hungary.
authors.forename: Vera
authors.initials: V
authors.lastname: Adam-Vizi
authors.affiliation: Department of Medical Biochemistry, Semmelweis University MTA-SE Laboratory for Neurobiochemistry, Budapest, 1094, Hungary.|MTA-SE Lendület Neurobiochemistry Research Group, Budapest, Hungary.
authors.forename: Christos
authors.initials: C
authors.lastname: Chinopoulos
mesh_terms: D033741:Adenine Nucleotide Translocator 1 / Q000172:deficiency*; D000001:Calcimycin / Q000494:pharmacology; D002478:Cells, Cultured; D005260:Female; D005347:Fibroblasts / Q000378:metabolism*; D055785:Gene Knockdown Techniques; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D008297:Male; D053078:Membrane Potential, Mitochondrial; D033681:Mitochondrial Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D051336:Mitochondrial Membranes / Q000378:metabolism*; D000083162:Mitochondrial Permeability Transition Pore
chemical_list: D033741:Adenine Nucleotide Translocator 1; D033681:Mitochondrial Membrane Transport Proteins; D000083162:Mitochondrial Permeability Transition Pore; C580832:SLC25A4 protein, human; D000001:Calcimycin; D006861:Hydrogen Peroxide