title: Selective superoxide generation within mitochondria by the targeted redox cycler MitoParaquat.
abstract: Superoxide is the proximal reactive oxygen species (ROS) produced by the mitochondrial respiratory chain and plays a major role in pathological oxidative stress and redox signaling. While there are tools to detect or decrease mitochondrial superoxide, none can rapidly and specifically increase superoxide production within the mitochondrial matrix. This lack impedes progress, making it challenging to assess accurately the roles of mitochondrial superoxide in cells and in vivo. To address this unmet need, we synthesized and characterized a mitochondria-targeted redox cycler, MitoParaquat (MitoPQ) that comprises a triphenylphosphonium lipophilic cation conjugated to the redox cycler paraquat. MitoPQ accumulates selectively in the mitochondrial matrix driven by the membrane potential. Within the matrix, MitoPQ produces superoxide by redox cycling at the flavin site of complex I, selectively increasing superoxide production within mitochondria. MitoPQ increased mitochondrial superoxide in isolated mitochondria and cells in culture ~a thousand-fold more effectively than untargeted paraquat. MitoPQ was also more toxic than paraquat in the isolated perfused heart and in Drosophila in vivo. MitoPQ enables the selective generation of superoxide within mitochondria and is a useful tool to investigate the many roles of mitochondrial superoxide in pathology and redox signaling in cells and in vivo.
authors.affiliation: MRC Mitochondrial Biology Unit, Hills Road, Cambridge CB2 0XY, UK.
authors.forename: Ellen L
authors.initials: EL
authors.lastname: Robb
authors.affiliation: WestCHEM School of Chemistry, University of Glasgow, Glasgow G12 8QQ, UK.
authors.forename: Justyna M
authors.initials: JM
authors.lastname: Gawel
authors.affiliation: King's College London, British Heart Foundation Centre of Research Excellence, The Rayne Institute, St Thomas' Hospital, London SE1 7EH, UK.
authors.forename: Dunja
authors.initials: D
authors.lastname: Aksentijević
authors.affiliation: MRC Clinical Sciences Centre, Imperial College London, Du Cane Road, London W12 0NN, UK.
authors.forename: Helena M
authors.initials: HM
authors.lastname: Cochemé
authors.affiliation: MRC Mitochondrial Biology Unit, Hills Road, Cambridge CB2 0XY, UK.
authors.forename: Tessa S
authors.initials: TS
authors.lastname: Stewart
authors.affiliation: WestCHEM School of Chemistry, University of Glasgow, Glasgow G12 8QQ, UK.
authors.forename: Maria M
authors.initials: MM
authors.lastname: Shchepinova
authors.affiliation: Key Laboratory of Adolescent Health Assessment and Exercise Intervention, Ministry of Education, East China Normal University, Shanghai 200241, China; College of Physical Education and Health, East China Normal University, Shanghai 200241, China.
authors.forename: He
authors.initials: H
authors.lastname: Qiang
authors.affiliation: MRC Mitochondrial Biology Unit, Hills Road, Cambridge CB2 0XY, UK.
authors.forename: Tracy A
authors.initials: TA
authors.lastname: Prime
authors.affiliation: MRC Mitochondrial Biology Unit, Hills Road, Cambridge CB2 0XY, UK.
authors.forename: Thomas P
authors.initials: TP
authors.lastname: Bright
authors.affiliation: MRC Mitochondrial Biology Unit, Hills Road, Cambridge CB2 0XY, UK.
authors.forename: Andrew M
authors.initials: AM
authors.lastname: James
authors.affiliation: King's College London, British Heart Foundation Centre of Research Excellence, The Rayne Institute, St Thomas' Hospital, London SE1 7EH, UK.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Shattock
authors.affiliation: WestCHEM School of Chemistry, University of Glasgow, Glasgow G12 8QQ, UK.
authors.forename: Hans M
authors.initials: HM
authors.lastname: Senn
authors.affiliation: WestCHEM School of Chemistry, University of Glasgow, Glasgow G12 8QQ, UK. Electronic address: Richard.Hartley@glasgow.ac.uk.
authors.forename: Richard C
authors.initials: RC
authors.lastname: Hartley
authors.affiliation: MRC Mitochondrial Biology Unit, Hills Road, Cambridge CB2 0XY, UK. Electronic address: mpm@mrc-mbu.cam.ac.uk.
authors.forename: Michael P
authors.initials: MP
authors.lastname: Murphy
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D015153:Blotting, Western; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D004331:Drosophila melanogaster / Q000187:drug effects / Q000378:metabolism; D042967:Electron Transport Complex I; D005260:Female; D045325:HCT116 Cells; D006540:Herbicides / Q000494:pharmacology*; D006801:Humans; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008929:Mitochondria, Heart / Q000187:drug effects / Q000378:metabolism*; D008930:Mitochondria, Liver / Q000187:drug effects / Q000378:metabolism*; D032446:Myoblasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D010084:Oxidation-Reduction; D018384:Oxidative Stress / Q000187:drug effects*; D010269:Paraquat / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D013481:Superoxides / Q000378:metabolism*
chemical_list: D006540:Herbicides; D017382:Reactive Oxygen Species; D013481:Superoxides; D042967:Electron Transport Complex I; D010269:Paraquat