title: CORM-3, a water soluble CO-releasing molecule, uncouples mitochondrial respiration via interaction with the phosphate carrier.
abstract: Carbon monoxide is continuously produced in small quantities in tissues and is an important signaling mediator in mammalian cells. We previously demonstrated that CO delivered to isolated rat heart mitochondria using a water-soluble CO-releasing molecule (CORM-3) is able to uncouple mitochondrial respiration. The aim of this study was to explore more in depth the mechanism(s) of this uncoupling effect. We found that acceleration of mitochondrial O2 consumption and decrease in membrane potential induced by CORM-3 were associated with an increase in mitochondrial swelling. This effect was independent of the opening of the mitochondrial transition pore as cyclosporine A was unable to prevent it. Interestingly, removal of phosphate from the incubation medium suppressed the effects mediated by CORM-3. Blockade of the dicarboxylate carrier, which exchanges dicarboxylate for phosphate, decreased the effects induced by CORM-3 while direct inhibition of the phosphate carrier with N-ethylmaleimide completely abolished the effects of CORM-3. In addition, CORM-3 was able to enhance the transport of phosphate into mitochondria as evidenced by changes in mitochondrial phosphate concentration and mitochondrial swelling that evaluates the activity of the phosphate carrier in de-energized conditions. These results indicate that CORM-3 activates the phosphate carrier leading to an increase in phosphate and proton transport inside mitochondria, both of which could contribute to the non-classical uncoupling effect mediated by CORM-3. The dicarboxylate carrier amplifies this effect by increasing intra-mitochondrial phosphate concentration.
authors.affiliation: INSERM U955, équipe 3, Faculté de Médecine, Université Paris Est, 94010 Creteil, France. Electronic address: romain.long@inserm.fr.
authors.forename: Romain
authors.initials: R
authors.lastname: Long
authors.forename: Issam
authors.initials: I
authors.lastname: Salouage
authors.forename: Alain
authors.initials: A
authors.lastname: Berdeaux
authors.forename: Roberto
authors.initials: R
authors.lastname: Motterlini
authors.forename: Didier
authors.initials: D
authors.lastname: Morin
mesh_terms: D000818:Animals; D002248:Carbon Monoxide / Q000378:metabolism; D019069:Cell Respiration / Q000502:physiology*; D053078:Membrane Potential, Mitochondrial; D008928:Mitochondria / Q000378:metabolism* / Q000502:physiology; D008929:Mitochondria, Heart / Q000378:metabolism*; D009942:Organometallic Compounds / Q000378:metabolism*; D010101:Oxygen Consumption; D028061:Phosphate Transport Proteins / Q000378:metabolism*; D011522:Protons; D051381:Rats; D014867:Water / Q000737:chemistry
chemical_list: D009942:Organometallic Compounds; D028061:Phosphate Transport Proteins; D011522:Protons; C476530:tricarbonylchloro(glycinato)ruthenium(II); D014867:Water; D002248:Carbon Monoxide
keywords: 2′,7′-bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein; BCECF; CO; CO-RMs; CO-releasing molecules; CORM-3; Carbon monoxide; DIC; Mitochondrial respiration; N-ethylmaleimide; NEM; Phosphate carrier; PiC; Ru(CO)(3)Cl(glycinate); Swelling; Uncoupling agents; carbon monoxide; dicarboxylate carrier; iCORM-3; inactive CORM-3; intramitochondrial pH; mPTP; mitochondrial permeability transition pore; pHi; phosphate carrier