title: Carbenoxolone induces permeability transition pore opening in rat mitochondria via the translocator protein TSPO and connexin43.
abstract: Ca(2+)-induced permeability transition pore (mPTP) opening in isolated rat brain mitochondria is promoted through targeting of connexin43. After a threshold Ca(2+) load, mitochondrial membrane potential drops and efflux of accumulated Ca(2+) from the mitochondrial matrix occurs, indicating the mPTP opening. Specific antibodies were used to assess the role of the translocator protein (18kDa; TSPO) and connexin43 in swelling of isolated rat liver and brain mitochondria induced by carbenoxolone and the endogenous TSPO ligand protoporphyrin IX. Mitochondrial membrane potential, Ca(2+) transport and oxygen consumption were determined using selective electrodes. All the parameters were detected simultaneously in a chamber with the selective electrodes. The phosphorylation state of mitochondrial protein targets was assessed. We report that Ca(2+)-induced mitochondrial swelling was strengthened in the presence of both carbenoxolone and protoporphyrin IX. The carbenoxolone- and protoporphyrin IX-accelerated mPTP induction in brain mitochondria was completely prevented by antibodies specific for the mitochondrial translocator protein (TSPO). The anti-TSPO antibodies were more effective than anti-сonnexin43 antibodies. Moreover, carbenoxolone-stimulated phosphorylation of mitochondrial proteins was inhibited by anti-TSPO antibodies. Taken together, the data suggests that, in addition to acting via connexion43, carbenoxolone may exert its effect on mPTP via mitochondrial outer membrane TSPO.
authors.affiliation: Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Institutskaya Str., Pushchino, Moscow Region 142290, Russia; Institut für Neurobiochemie, Otto-von-Guericke-Universität Magdeburg, Medizinische Fakultät, Leipziger Str. 44, 39120 Magdeburg, Germany. Electronic address: tamara.azarashvili@gmail.com.
authors.forename: Tamara
authors.initials: T
authors.lastname: Azarashvili
authors.affiliation: Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Institutskaya Str., Pushchino, Moscow Region 142290, Russia. Electronic address: byul@rambler.ru.
authors.forename: Yulia
authors.initials: Y
authors.lastname: Baburina
authors.affiliation: Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Institutskaya Str., Pushchino, Moscow Region 142290, Russia. Electronic address: grachew@rambler.ru.
authors.forename: Dmitry
authors.initials: D
authors.lastname: Grachev
authors.affiliation: Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Institutskaya Str., Pushchino, Moscow Region 142290, Russia. Electronic address: krestinina@rambler.ru.
authors.forename: Olga
authors.initials: O
authors.lastname: Krestinina
authors.affiliation: The Research Institute of the McGill University Health Center, 2155 Guy Street, Suite 500, Montreal, Quebec H3H 2R9, Canada. Electronic address: vassilios.papadopoulos@mcgill.ca.
authors.forename: Vassilios
authors.initials: V
authors.lastname: Papadopoulos
authors.affiliation: Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Institutskaya Str., Pushchino, Moscow Region 142290, Russia; Department of Drug Discovery & Biomedical Sciences, Medical University of South Carolina, DD504 Drug Discovery Bldg., 70 President St., MSC 140, Charleston, SC 29425, USA; Department of Biochemistry & Molecular Biology, Medical University of South Carolina, DD504 Drug Discovery Bldg., 70 President St., MSC 140, Charleston, SC 29425, USA. Electronic address: JJLemasters@musc.edu.
authors.forename: John J
authors.initials: JJ
authors.lastname: Lemasters
authors.affiliation: Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Institutskaya Str., Pushchino, Moscow Region 142290, Russia. Electronic address: odinokova@rambler.ru.
authors.forename: Irina
authors.initials: I
authors.lastname: Odinokova
authors.affiliation: Institut für Neurobiochemie, Otto-von-Guericke-Universität Magdeburg, Medizinische Fakultät, Leipziger Str. 44, 39120 Magdeburg, Germany. Electronic address: georg.reiser@med.ovgu.de.
authors.forename: Georg
authors.initials: G
authors.lastname: Reiser
mesh_terms: D000818:Animals; D001921:Brain / Q000166:cytology; D002118:Calcium / Q000494:pharmacology; D002229:Carbenoxolone / Q000494:pharmacology*; D002352:Carrier Proteins / Q000378:metabolism*; D018031:Connexin 43 / Q000378:metabolism*; D008099:Liver / Q000166:cytology; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D033681:Mitochondrial Membrane Transport Proteins / Q000737:chemistry* / Q000378:metabolism; D000083162:Mitochondrial Permeability Transition Pore; D010766:Phosphorylation / Q000187:drug effects; D011487:Protein Conformation / Q000187:drug effects; D011524:Protoporphyrins / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D011963:Receptors, GABA-A / Q000378:metabolism*
chemical_list: D002352:Carrier Proteins; D018031:Connexin 43; D033681:Mitochondrial Membrane Transport Proteins; D000083162:Mitochondrial Permeability Transition Pore; D011524:Protoporphyrins; D011963:Receptors, GABA-A; C069997:Tspo protein, rat; C028025:protoporphyrin IX; D002229:Carbenoxolone; D002118:Calcium
keywords: Carbenoxolone; Connexins; Mitochondria; Permeability transition pore; Protoporphyrin IX; TSPO