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da Silva EFF, Pimenta FM, Pedersen BW, Blaikie FH, Bosio GN, Breitenbach T, Westberg M, Bregnhøj M, Etzerodt M, Arnaut LG, Ogilby PR. Intracellular singlet oxygen photosensitizers: on the road to solving the problems of sensitizer degradation, bleaching and relocalization. Integr Biol (Camb) 2016; 8:177-93. [DOI: 10.1039/c5ib00295h] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Elsa F. F. da Silva
- Center for Oxygen Microscopy and Imaging, Department of Chemistry, Aarhus University, DK-8000, Århus, Denmark
- Department of Chemistry, University of Coimbra, 3004-535 Coimbra, Portugal
| | - Frederico M. Pimenta
- Center for Oxygen Microscopy and Imaging, Department of Chemistry, Aarhus University, DK-8000, Århus, Denmark
| | - Brian W. Pedersen
- Center for Oxygen Microscopy and Imaging, Department of Chemistry, Aarhus University, DK-8000, Århus, Denmark
| | - Frances H. Blaikie
- Center for Oxygen Microscopy and Imaging, Department of Chemistry, Aarhus University, DK-8000, Århus, Denmark
| | - Gabriela N. Bosio
- Center for Oxygen Microscopy and Imaging, Department of Chemistry, Aarhus University, DK-8000, Århus, Denmark
- Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), CCT-La Plata-CONICET, Universidad Nacional de La Plata, Casilla de Correo 16, sucursal 4 (1900), La Plata, Argentina
| | - Thomas Breitenbach
- Center for Oxygen Microscopy and Imaging, Department of Chemistry, Aarhus University, DK-8000, Århus, Denmark
| | - Michael Westberg
- Center for Oxygen Microscopy and Imaging, Department of Chemistry, Aarhus University, DK-8000, Århus, Denmark
| | - Mikkel Bregnhøj
- Center for Oxygen Microscopy and Imaging, Department of Chemistry, Aarhus University, DK-8000, Århus, Denmark
| | - Michael Etzerodt
- Department of Molecular Biology and Genetics, Aarhus University, DK-8000 Aarhus, Denmark
| | - Luis G. Arnaut
- Department of Chemistry, University of Coimbra, 3004-535 Coimbra, Portugal
| | - Peter R. Ogilby
- Center for Oxygen Microscopy and Imaging, Department of Chemistry, Aarhus University, DK-8000, Århus, Denmark
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2
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Pedersen SK, Holmehave J, Blaikie FH, Gollmer A, Breitenbach T, Jensen HH, Ogilby PR. Aarhus Sensor Green: A Fluorescent Probe for Singlet Oxygen. J Org Chem 2014; 79:3079-87. [DOI: 10.1021/jo500219y] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Stephan K. Pedersen
- Center
for Oxygen Microscopy
and Imaging, Department of Chemistry, Aarhus University, Langelandsgade
140, Aarhus 8000, Denmark
| | - Jeppe Holmehave
- Center
for Oxygen Microscopy
and Imaging, Department of Chemistry, Aarhus University, Langelandsgade
140, Aarhus 8000, Denmark
| | - Frances H. Blaikie
- Center
for Oxygen Microscopy
and Imaging, Department of Chemistry, Aarhus University, Langelandsgade
140, Aarhus 8000, Denmark
| | - Anita Gollmer
- Center
for Oxygen Microscopy
and Imaging, Department of Chemistry, Aarhus University, Langelandsgade
140, Aarhus 8000, Denmark
| | - Thomas Breitenbach
- Center
for Oxygen Microscopy
and Imaging, Department of Chemistry, Aarhus University, Langelandsgade
140, Aarhus 8000, Denmark
| | - Henrik H. Jensen
- Center
for Oxygen Microscopy
and Imaging, Department of Chemistry, Aarhus University, Langelandsgade
140, Aarhus 8000, Denmark
| | - Peter R. Ogilby
- Center
for Oxygen Microscopy
and Imaging, Department of Chemistry, Aarhus University, Langelandsgade
140, Aarhus 8000, Denmark
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3
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Bosio GN, Breitenbach T, Parisi J, Reigosa M, Blaikie FH, Pedersen BW, Silva EFF, Mártire DO, Ogilby PR. Antioxidant β-Carotene Does Not Quench Singlet Oxygen in Mammalian Cells. J Am Chem Soc 2012; 135:272-9. [DOI: 10.1021/ja308930a] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- Gabriela N. Bosio
- Instituto de Investigaciones
Fisicoquímicas Teóricas y Aplicadas (INIFTA), CCT-La
Plata-CONICET, Universidad Nacional de La Plata, Casilla de Correo 16, Sucursal 4 (1900), La Plata, Argentina
- Center for Oxygen Microscopy
and Imaging, Department of Chemistry, Aarhus University, Langelandsgade 140, Århus 8000, Denmark
| | - Thomas Breitenbach
- Center for Oxygen Microscopy
and Imaging, Department of Chemistry, Aarhus University, Langelandsgade 140, Århus 8000, Denmark
| | - Julieta Parisi
- Instituto Multidisciplinario de
Biologia Celular (IMBICE), CCT-La Plata-CONICET, Camino General Belgrano
y 526, B1906APO, La Plata, Argentina
| | - Miguel Reigosa
- Instituto Multidisciplinario de
Biologia Celular (IMBICE), CCT-La Plata-CONICET, Camino General Belgrano
y 526, B1906APO, La Plata, Argentina
| | - Frances H. Blaikie
- Center for Oxygen Microscopy
and Imaging, Department of Chemistry, Aarhus University, Langelandsgade 140, Århus 8000, Denmark
| | - Brian W. Pedersen
- Center for Oxygen Microscopy
and Imaging, Department of Chemistry, Aarhus University, Langelandsgade 140, Århus 8000, Denmark
| | - Elsa F. F. Silva
- Center for Oxygen Microscopy
and Imaging, Department of Chemistry, Aarhus University, Langelandsgade 140, Århus 8000, Denmark
- Department of Chemistry, University of Coimbra, 3004 Coimbra, Portugal
| | - Daniel O. Mártire
- Instituto de Investigaciones
Fisicoquímicas Teóricas y Aplicadas (INIFTA), CCT-La
Plata-CONICET, Universidad Nacional de La Plata, Casilla de Correo 16, Sucursal 4 (1900), La Plata, Argentina
| | - Peter R. Ogilby
- Center for Oxygen Microscopy
and Imaging, Department of Chemistry, Aarhus University, Langelandsgade 140, Århus 8000, Denmark
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4
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Gollmer A, Arnbjerg J, Blaikie FH, Pedersen BW, Breitenbach T, Daasbjerg K, Glasius M, Ogilby PR. Singlet Oxygen Sensor Green®: Photochemical Behavior in Solution and in a Mammalian Cell. Photochem Photobiol 2011; 87:671-9. [DOI: 10.1111/j.1751-1097.2011.00900.x] [Citation(s) in RCA: 196] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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5
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Brown KK, Blaikie FH, Smith RAJ, Tyndall JDA, Lue H, Bernhagen J, Winterbourn CC, Hampton MB. Direct modification of the proinflammatory cytokine macrophage migration inhibitory factor by dietary isothiocyanates. J Biol Chem 2009; 284:32425-33. [PMID: 19776019 PMCID: PMC2781657 DOI: 10.1074/jbc.m109.047092] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2009] [Revised: 09/14/2009] [Indexed: 11/06/2022] Open
Abstract
Isothiocyanates are a class of phytochemicals with widely reported anti-cancer and anti-inflammatory activity. However, knowledge of their activity at a molecular level is limited. The objective of this study was to identify biological targets of phenethyl isothiocyanate (PEITC) using an affinity purification approach. An analogue of PEITC was synthesized to enable conjugation to a solid-phase resin. The pleiotropic cytokine macrophage migration inhibitory factor (MIF) was the major protein captured from cell lysates. Site-directed mutagenesis and mass spectrometry showed that PEITC covalently modified the N-terminal proline residue of MIF. This resulted in complete loss of catalytic tautomerase activity and disruption of protein conformation, as determined by impaired recognition by a monoclonal antibody directed to the region that receptors and interacting proteins bind to MIF. The conformational change was supported by in silico modeling. Monoclonal antibody binding to plasma MIF was disrupted in humans consuming watercress, a major dietary source of PEITC. The isothiocyanates have significant potential for development as MIF inhibitors, and this activity may contribute to the biological properties of these phytochemicals.
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Affiliation(s)
- Kristin K. Brown
- From the
Free Radical Research Group, Department of Pathology, University of Otago, Christchurch 8140, New Zealand
| | | | | | - Joel D. A. Tyndall
- the
National School of Pharmacy, University of Otago, Dunedin 9054, New Zealand, and
| | - Hongqi Lue
- the
Department of Biochemistry and Molecular Cell Biology, Institute of Biochemistry and Molecular Biology, Rheinisch-Westfälische Technische Hochschule (RWTH) Aachen University, Aachen 52074, Germany
| | - Jürgen Bernhagen
- the
Department of Biochemistry and Molecular Cell Biology, Institute of Biochemistry and Molecular Biology, Rheinisch-Westfälische Technische Hochschule (RWTH) Aachen University, Aachen 52074, Germany
| | - Christine C. Winterbourn
- From the
Free Radical Research Group, Department of Pathology, University of Otago, Christchurch 8140, New Zealand
| | - Mark B. Hampton
- From the
Free Radical Research Group, Department of Pathology, University of Otago, Christchurch 8140, New Zealand
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Abstract
Piperidine nitroxides such as TEMPOL have been widely used as antioxidants in vitro and in vivo. MitoTEMPOL is a mitochondria-targeted derivative of TEMPOL designed to protect mitochondria from the oxidative damage that they accumulate, but once there is rapidly reduced to its hydroxylamine, MitoTEMPOL-H. As little is known about the antioxidant efficacy of hydroxylamines, this study has assessed the antioxidant activity of both MitoTEMPOL and MitoTEMPOL-H. The hydroxylamine was more effective at preventing lipid-peroxidation than MitoTEMPOL and decreased oxidative damage to mitochondrial DNA caused by menadione. In contrast to MitoTEMPOL, MitoTEMPOL-H has no superoxide dismutase activity and its antioxidant actions are likely to be mediated by hydrogen atom donation. Therefore, even though MitoTEMPOL is rapidly reduced to MitoTEMPOL-H in cells, it remains an effective antioxidant. Furthermore, as TEMPOL is also reduced to a hydroxylamine in vivo, many of its antioxidant effects may also be mediated by its hydroxylamine.
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Affiliation(s)
- Jan Trnka
- MRC Dunn Human Nutrition Unit, Cambridge, UK
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Smith RAJ, Adlam VJ, Blaikie FH, Manas ARB, Porteous CM, James AM, Ross MF, Logan A, Cochemé HM, Trnka J, Prime TA, Abakumova I, Jones BA, Filipovska A, Murphy MP. Mitochondria-targeted antioxidants in the treatment of disease. Ann N Y Acad Sci 2009; 1147:105-11. [PMID: 19076435 DOI: 10.1196/annals.1427.003] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Mitochondrial oxidative damage is thought to contribute to a wide range of human diseases; therefore, the development of approaches to decrease this damage may have therapeutic potential. Mitochondria-targeted antioxidants that selectively block mitochondrial oxidative damage and prevent some types of cell death have been developed. These compounds contain antioxidant moieties, such as ubiquinone, tocopherol, or nitroxide, that are targeted to mitochondria by covalent attachment to a lipophilic triphenylphosphonium cation. Because of the large mitochondrial membrane potential, the cations are accumulated within the mitochondria inside cells. There, the conjugated antioxidant moiety protects mitochondria from oxidative damage. Here, we outline some of the work done to date on these compounds and how they may be developed as therapies.
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Affiliation(s)
- Robin A J Smith
- Department of Chemistry, University of Otago, Dunedin, New Zealand
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Trnka J, Blaikie FH, Smith RAJ, Murphy MP. A mitochondria-targeted nitroxide is reduced to its hydroxylamine by ubiquinol in mitochondria. Free Radic Biol Med 2008; 44:1406-19. [PMID: 18206669 DOI: 10.1016/j.freeradbiomed.2007.12.036] [Citation(s) in RCA: 182] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/16/2007] [Revised: 12/20/2007] [Accepted: 12/20/2007] [Indexed: 12/31/2022]
Abstract
Piperidine nitroxides such as TEMPOL act as antioxidants in vivo due to their interconversion among nitroxide, hydroxylamine, and oxoammonium derivatives, but the mechanistic details of these reactions are unclear. As mitochondria are a significant site of piperidine nitroxide metabolism and action, we synthesized a mitochondria-targeted nitroxide, MitoTEMPOL, by conjugating TEMPOL to the lipophilic triphenylphosphonium cation. MitoTEMPOL was accumulated several hundred-fold into energized mitochondria where it was reduced to the hydroxylamine by direct reaction with ubiquinol. This reaction occurred by transfer of H() from ubiquinol to the nitroxide, with the ubisemiquinone radical product predominantly dismutating to ubiquinone and ubiquinol, together with a small amount reacting with oxygen to form superoxide. The piperidine nitroxides TEMPOL, TEMPO, and butylTEMPOL reacted similarly with ubiquinol in organic solvents but in mitochondrial membranes the rates varied in the order: MitoTEMPOL > butylTEMPOL > TEMPO > TEMPOL, which correlated with the extent of access of the nitroxide moiety to ubiquinol within the membrane. These findings suggest ways of using mitochondria-targeted compounds to modulate the coenzyme Q pool within mitochondria in vivo, and indicate that the antioxidant effects of mitochondria-targeted piperidine nitroxides can be ascribed to their corresponding hydroxylamines.
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Affiliation(s)
- Jan Trnka
- Medical Research Council Dunn Human Nutrition Unit, Wellcome Trust/MRC Building, Hills Road, Cambridge CB2 0XY, UK
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9
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Cochemé HM, Kelso GF, James AM, Ross MF, Trnka J, Mahendiran T, Asin-Cayuela J, Blaikie FH, Manas ARB, Porteous CM, Adlam VJ, Smith RAJ, Murphy MP. Mitochondrial targeting of quinones: therapeutic implications. Mitochondrion 2007; 7 Suppl:S94-102. [PMID: 17449335 DOI: 10.1016/j.mito.2007.02.007] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2006] [Revised: 02/12/2007] [Accepted: 02/19/2007] [Indexed: 01/11/2023]
Abstract
Mitochondrial oxidative damage contributes to a range of degenerative diseases. Ubiquinones have been shown to protect mitochondria from oxidative damage, but only a small proportion of externally administered ubiquinone is taken up by mitochondria. Conjugation of the lipophilic triphenylphosphonium cation to a ubiquinone moiety has produced a compound, MitoQ, which accumulates selectively into mitochondria. MitoQ passes easily through all biological membranes and, because of its positive charge, is accumulated several hundred-fold within mitochondria driven by the mitochondrial membrane potential. MitoQ protects mitochondria against oxidative damage in vitro and following oral delivery, and may therefore form the basis for mitochondria-protective therapies.
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Affiliation(s)
- Helena M Cochemé
- MRC Dunn Human Nutrition Unit, Wellcome Trust/MRC Building, Hills Road, Cambridge CB2 2XY, UK
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Blaikie FH, Brown SE, Samuelsson LM, Brand MD, Smith RAJ, Murphy MP. Targeting Dinitrophenol to Mitochondria: Limitations to the Development of a Self-limiting Mitochondrial Protonophore. Biosci Rep 2006; 26:231-43. [PMID: 16850251 DOI: 10.1007/s10540-006-9018-8] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
The protonmotive force (Δp) across the mitochondrial inner membrane drives ATP synthesis. In addition, the energy stored in Δp can be dissipated by proton leak through the inner membrane, contributing to basal metabolic rate and thermogenesis. Increasing mitochondrial proton leak pharmacologically should decrease the efficiency of oxidative phosphorylation and counteract obesity by enabling fatty acids to be oxidised with decreased ATP production. While protonophores such as 2,4-dinitrophenol (DNP) increase mitochondrial proton leak and have been used to treat obesity, a slight increase in DNP concentration above the therapeutically effective dose disrupts mitochondrial function and leads to toxicity. Therefore we set out to develop a less toxic protonophore that would increase proton leak significantly at high Δp but not at low Δp. Our design concept for a potential self-limiting protonophore was to couple the DNP moiety to the lipophilic triphenylphosphonium (TPP) cation and this was achieved by the preparation of 3-(3,5-dinitro-4-hydroxyphenyl)propyltriphenylphosphonium methanesulfonate (MitoDNP). TPP cations accumulate within mitochondria driven by the membrane potential (Δψ), the predominant component of Δp. Our hypothesis was that MitoDNP would accumulate in mitochondria at high Δψ where it would act as a protonophore, but that at lower Δψ the accumulation and uncoupling would be far less. We found that MitoDNP was extensively taken into mitochondria driven by Δψ. However MitoDNP did not uncouple mitochondria as judged by its inability to either increase respiration rate or decrease Δψ. Therefore MitoDNP did not act as a protonophore, probably because the efflux of deprotonated MitoDNP was inhibited.
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Affiliation(s)
- Frances H Blaikie
- Department of Chemistry, University of Otago, P O Box 56, Dunedin, New Zealand
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Ross MF, Kelso GF, Blaikie FH, James AM, Cochemé HM, Filipovska A, Da Ros T, Hurd TR, Smith RAJ, Murphy MP. Lipophilic triphenylphosphonium cations as tools in mitochondrial bioenergetics and free radical biology. Biochemistry (Mosc) 2005; 70:222-30. [PMID: 15807662 DOI: 10.1007/s10541-005-0104-5] [Citation(s) in RCA: 299] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Lipophilic phosphonium cations were first used to investigate mitochondrial biology by Vladimir Skulachev and colleagues in the late 1960s. Since then, these molecules have become important tools for exploring mitochondrial bioenergetics and free radical biology. Here we review why these molecules are useful in mitochondrial research and outline some of the ways in which they are now being utilized.
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Affiliation(s)
- M F Ross
- MRC Dunn Human Nutrition Unit, Cambridge, CB2 2XY, UK
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12
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Murphy MP, Echtay KS, Blaikie FH, Asin-Cayuela J, Cocheme HM, Green K, Buckingham JA, Taylor ER, Hurrell F, Hughes G, Miwa S, Cooper CE, Svistunenko DA, Smith RAJ, Brand MD. Superoxide activates uncoupling proteins by generating carbon-centered radicals and initiating lipid peroxidation: studies using a mitochondria-targeted spin trap derived from alpha-phenyl-N-tert-butylnitrone. J Biol Chem 2003; 278:48534-45. [PMID: 12972420 DOI: 10.1074/jbc.m308529200] [Citation(s) in RCA: 239] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Although the physiological role of uncoupling proteins (UCPs) 2 and 3 is uncertain, their activation by superoxide and by lipid peroxidation products suggest that UCPs are central to the mitochondrial response to reactive oxygen species. We examined whether superoxide and lipid peroxidation products such as 4-hydroxy-2-trans-nonenal act independently to activate UCPs, or if they share a common pathway, perhaps by superoxide exposure leading to the formation of lipid peroxidation products. This possibility can be tested by blocking the putative reactive oxygen species cascade with selective antioxidants and then reactivating UCPs with distal cascade components. We synthesized a mitochondria-targeted derivative of the spin trap alpha-phenyl-N-tert-butylnitrone, which reacts rapidly with carbon-centered radicals but is unreactive with superoxide and lipid peroxidation products. [4-[4-[[(1,1-Dimethylethyl)-oxidoimino]methyl]phenoxy]butyl]triphenylphosphonium bromide (MitoPBN) prevented the activation of UCPs by superoxide but did not block activation by hydroxynonenal. This was not due to MitoPBN reacting with superoxide or the hydroxyl radical or by acting as a chain-breaking antioxidant. MitoPBN did react with carbon-centered radicals and also prevented lipid peroxidation by the carbon-centered radical generator 2,2'-azobis(2-methyl propionamidine) dihydrochloride (AAPH). Furthermore, AAPH activated UCPs, and this was blocked by MitoPBN. These data suggest that superoxide and lipid peroxidation products share a common pathway for the activation of UCPs. Superoxide releases iron from iron-sulfur center proteins, which then generates carbon-centered radicals that initiate lipid peroxidation, yielding breakdown products that activate UCPs.
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Affiliation(s)
- Michael P Murphy
- Medical Research Council Dunn Human Nutrition Unit, Wellcome Trust-MRC Building, Hills Road, Cambridge CB2 2XY, United Kingdom.
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13
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Smith RAJ, Kelso GF, Blaikie FH, Porteous CM, Ledgerwood EC, Hughes G, James AM, Ross MF, Asin-Cayuela J, Cochemé HM, Filipovska A, Murphy MP. Using mitochondria-targeted molecules to study mitochondrial radical production and its consequences. Biochem Soc Trans 2003; 31:1295-9. [PMID: 14641046 DOI: 10.1042/bst0311295] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The production of ROS (reactive oxygen species) by the mitochondrial respiratory chain contributes to a range of pathologies, including neurodegenerative diseases, ischaemia/reperfusion injury and aging. There are also indications that mitochondrial ROS production plays a role in damage response and signal transduction pathways. To unravel the role of mitochondrial ROS production in these processes, we have developed a range of mitochondria-targeted probe molecules. Covalent attachment of a lipophilic cation leads to their accumulation into mitochondria, driven by the membrane potential. Molecules developed so far include antioxidants designed to intercept mitochondrial ROS and reagents that specifically label mitochondrial thiol proteins. Here we outline how mitochondrial ROS formation and its consequences can be investigated using these probes.
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Affiliation(s)
- R A J Smith
- Department of Chemistry, University of Otago, Box 56, Dunedin, New Zealand
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14
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James AM, Blaikie FH, Smith RAJ, Lightowlers RN, Smith PM, Murphy MP. Specific targeting of a DNA-alkylating reagent to mitochondria. Synthesis and characterization of [4-((11aS)-7-methoxy-1,2,3,11a-tetrahydro-5H-pyrrolo[2,1-c][1,4]benzodiazepin-5-on-8-oxy)butyl]-triphenylphosphonium iodide. Eur J Biochem 2003; 270:2827-36. [PMID: 12823553 DOI: 10.1046/j.1432-1033.2003.03660.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The selective manipulation of the expression and replication of mitochondrial DNA (mtDNA) within mammalian cells has proven difficult. In progressing towards this goal we synthesized a novel mitochondria-targeted DNA-alkylating reagent. The active alkylating moiety [(11aS)-8-hydroxy-7-methoxy-1,2,3,11a-tetrahydro-5H-pyrrolo[2,1-c][1,4]benzodiazepin-5-one (DC-81)], irreversibly alkylates guanine bases in DNA (with a preference for AGA triplets), preventing its expression and replication. To target this compound to mitochondria it was covalently coupled to the lipophilic triphenylphosphonium (TPP) cation to form a derivative referred to as mitoDC-81. Incorporation of this lipophilic cation led to the rapid uptake of mitoDC-81 by mitochondria, driven by the large membrane potential across the inner membrane. This compound efficiently alkylated isolated supercoiled, relaxed-circular or linear plasmid DNA and isolated mtDNA. However mitoDC-81 did not alkylate mtDNA within isolated mitochondria or cells, even though it accessed the mitochondrial matrix at concentrations up to 100-fold higher than those required to alkylate isolated DNA. This surprising finding suggests that mtDNA within intact mitochondria may not be accessible to this class of alkylating reagent. This inability to alkylate mtDNA in situ has significant implications for the design of therapies for mtDNA diseases and for studies on the packaging, expression and turnover of mtDNA in general.
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Affiliation(s)
- Andrew M James
- MRC-Dunn Human Nutrition Unit, Wellcome Trust-MRC Building, Cambridge, UK
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15
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Lin TK, Hughes G, Muratovska A, Blaikie FH, Brookes PS, Darley-Usmar V, Smith RAJ, Murphy MP. Specific modification of mitochondrial protein thiols in response to oxidative stress: a proteomics approach. J Biol Chem 2002; 277:17048-56. [PMID: 11861642 DOI: 10.1074/jbc.m110797200] [Citation(s) in RCA: 144] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mitochondria play a central role in redox-linked processes in the cell through mechanisms that are thought to involve modification of specific protein thiols, but this has proved difficult to assess. In particular, specific labeling and quantitation of mitochondrial protein cysteine residues have not been achieved due to the lack of reagents available that can be applied to the intact organelle or cell. To overcome these problems we have used a combination of mitochondrial proteomics and targeted labeling of mitochondrial thiols using a novel compound, (4-iodobutyl)triphenylphosphonium (IBTP). This lipophilic cation is accumulated by mitochondria and yields stable thioether adducts in a thiol-specific reaction. The selective uptake into mitochondria, due to the large membrane potential across the inner membrane, and the high pH of the matrix results in specific labeling of mitochondrial protein thiols by IBTP. Individual mitochondrial proteins that changed thiol redox state following oxidative stress could then be identified by their decreased reaction with IBTP and isolated by two-dimensional electrophoresis. We demonstrate the selectivity of IBTP labeling and use it to show that glutathione oxidation and exposure to an S-nitrosothiol or to peroxynitrite cause extensive redox changes to mitochondrial thiol proteins. In conjunction with blue native gel electrophoresis, we used IBTP labeling to demonstrate that thiols are exposed on the matrix faces of respiratory Complexes I, II, and IV. This novel approach enables measurement of the thiol redox state of individual mitochondrial proteins during oxidative stress and cell death. In addition the methodology has the potential to identify novel redox-dependent modulation of mitochondrial proteins.
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Affiliation(s)
- Tsu-Kung Lin
- Department of Biochemistry, University of Otago, Box 56, Dunedin, New Zealand
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