19 results on '"Caldwell, Stuart T."'
Search Results
2. MitoNeoD: A Mitochondria-Targeted Superoxide Probe
- Author
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Shchepinova, Maria M., Cairns, Andrew G., Prime, Tracy A., Logan, Angela, James, Andrew M., Hall, Andrew R., Vidoni, Sara, Arndt, Sabine, Caldwell, Stuart T., Prag, Hiran A., Pell, Victoria R., Krieg, Thomas, Mulvey, John F., Yadav, Pooja, Cobley, James N., Bright, Thomas P., Senn, Hans M., Anderson, Robert F., Murphy, Michael P., and Hartley, Richard C.
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- 2017
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3. Rapid and selective generation of H2S within mitochondria protects against cardiac ischemia-reperfusion injury
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Miljkovic, Jan Lj., primary, Burger, Nils, additional, Gawel, Justyna M., additional, Mulvey, John F., additional, Norman, Abigail A.I., additional, Nishimura, Takanori, additional, Tsujihata, Yoshiyuki, additional, Logan, Angela, additional, Sauchanka, Olga, additional, Caldwell, Stuart T., additional, Morris, Jordan L., additional, Prime, Tracy A., additional, Warrington, Stefan, additional, Prudent, Julien, additional, Bates, Georgina R., additional, Aksentijević, Dunja, additional, Prag, Hiran A., additional, James, Andrew M., additional, Krieg, Thomas, additional, Hartley, Richard C., additional, and Murphy, Michael P., additional
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- 2022
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4. Ester Prodrugs of Malonate with Enhanced Intracellular Delivery Protect Against Cardiac Ischemia-Reperfusion Injury In Vivo
- Author
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Prag, Hiran, Pala, Laura, Kula-Alwar, Duvaraka, Mulvey, John F, Luping, Du, Beach, Timothy E, Booty, Lee M, Hall, Andrew R, Logan, Angela, Sauchanka, Volha, Caldwell, Stuart T, Robb, Ellen L, James, Andrew, Xu, Zhelong, Saeb-Parsy, Kourosh, Hartley, Richard C, Murphy, Mike, Krieg, Thomas, Krieg, Thomas [0000-0002-5192-580X], Apollo - University of Cambridge Repository, Prag, Hiran [0000-0002-4753-8567], Saeb-Parsy, Kourosh [0000-0002-0633-3696], and Murphy, Mike [0000-0003-1115-9618]
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Male ,Succinate ,Cardiotonic Agents ,Malonate ,Myocardial Infarction ,Succinic Acid ,Esters ,Myocardial Reperfusion Injury ,Ischemia/reperfusion injury ,Malonates ,Mitochondria ,Cell Line ,Rats ,Mice, Inbred C57BL ,Disease Models, Animal ,Mice ,Drug delivery ,Animals ,Humans ,Female ,Prodrugs ,Rats, Wistar ,Reactive Oxygen Species - Abstract
Purpose:\ud \ud Mitochondrial reactive oxygen species (ROS) production upon reperfusion of ischemic tissue initiates the ischemia/reperfusion (I/R) injury associated with heart attack. During ischemia, succinate accumulates and its oxidation upon reperfusion by succinate dehydrogenase (SDH) drives ROS production. Inhibition of succinate accumulation and/or oxidation by dimethyl malonate (DMM), a cell permeable prodrug of the SDH inhibitor malonate, can decrease I/R injury. However, DMM is hydrolysed slowly, requiring administration to the heart prior to ischemia, precluding its administration to patients at the point of reperfusion, for example at the same time as unblocking a coronary artery following a heart attack. To accelerate malonate delivery, here we developed more rapidly hydrolysable malonate esters.\ud \ud Methods:\ud \ud We synthesised a series of malonate esters and assessed their uptake and hydrolysis by isolated mitochondria, C2C12 cells and in mice in vivo. In addition, we assessed protection against cardiac I/R injury by the esters using an in vivo mouse model of acute myocardial infarction.\ud \ud Results:\ud \ud We found that the diacetoxymethyl malonate diester (MAM) most rapidly delivered large amounts of malonate to cells in vivo. Furthermore, MAM could inhibit mitochondrial ROS production from succinate oxidation and was protective against I/R injury in vivo when added at reperfusion.\ud \ud Conclusions:\ud \ud The rapidly hydrolysed malonate prodrug MAM can protect against cardiac I/R injury in a clinically relevant mouse model.
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- 2022
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5. Itaconate is an anti-inflammatory metabolite that activates Nrf2 via alkylation of KEAP1
- Author
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Mills, Evanna L., Ryan, Dylan G., Prag, Hiran A., Dikovskaya, Dina, Menon, Deepthi, Zaslona, Zbigniew, Jedrychowski, Mark P., Costa, Ana S. H., Higgins, Maureen, Hams, Emily, Szpyt, John, Runtsch, Marah C., King, Martin S., McGouran, Joanna F., Fischer, Roman, Kessler, Benedikt M., McGettrick, Anne F., Hughes, Mark M., Carroll, Richard G., Booty, Lee M., Knatko, Elena V., Meakin, Paul J., Ashford, Michael L. J., Modis, Louise K., Brunori, Gino, Svin, Daniel C., Fallon, Padraic G., Caldwell, Stuart T., Kunji, Edmund R. S., Chouchani, Edward T., Frezza, Christian, Dinkova-Kostova, Albena T., Hartley, Richard C., Murphy, Michael P., and ONeill, Luke A.
- Subjects
Metabolites -- Research ,Physiological research ,Activation analysis ,Leucine zipper -- Research ,Environmental issues ,Science and technology ,Zoology and wildlife conservation - Abstract
Author(s): Evanna L. Mills [1, 2, 3, 4]; Dylan G. Ryan [1]; Hiran A. Prag [5]; Dina Dikovskaya [6]; Deepthi Menon [1]; Zbigniew Zaslona [1]; Mark P. Jedrychowski [2, 3]; [...]
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- 2018
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6. Targeting Methylglyoxal in Diabetic Kidney Disease Using the Mitochondria-Targeted Compound MitoGamide
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Tan, Sih Min, primary, Lindblom, Runa S. J., additional, Ziemann, Mark, additional, Laskowski, Adrienne, additional, Granata, Cesare, additional, Snelson, Matthew, additional, Thallas-Bonke, Vicki, additional, El-Osta, Assam, additional, Baeza-Garza, Carlos D., additional, Caldwell, Stuart T., additional, Hartley, Richard C., additional, Krieg, Thomas, additional, Cooper, Mark E., additional, Murphy, Michael P., additional, and Coughlan, Melinda T., additional
- Published
- 2021
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7. Synthesis of polyhydroxylated flavonoids bearing a lipophilic decyl tail as potential therapeutic antioxidants
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Caldwell, Stuart T., McPhail, Donald B., Duthie, Garry G., and Hartley, Richard C.
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Stroke (Disease) -- Care and treatment ,Bioflavonoids -- Chemical properties -- Production processes -- Composition ,Flavones -- Chemical properties -- Production processes -- Composition ,Antioxidants -- Chemical properties -- Composition -- Production processes ,Nervous system -- Degeneration ,Chemical synthesis -- Methods ,Flavonoids -- Chemical properties -- Production processes -- Composition ,Chemistry - Abstract
Antioxidants have potential for the treatment of stroke and neurodegeneration, and chimeric compounds that combine a flavon-3-ol head group related to myricetin and a lipophilic decyl tail are known to protect membranes from oxidative damage at least as well as vitamin E. New flavon-3-ols that are highly hydroxylated in the B ring in ways not found in natural flavon-3-ols and bearing a lipophilic decyl tail have been prepared from trimethoxy- and tetramethoxybenzoic acids accessed by lithiation-carboxylation reactions. Direct enolate acylation was preferred over Baker-Venkataraman rearrangement when there were methoxy groups at both the 2- and the 6-position of the benzoic acid derivatives. Key words: flavonol, antioxidant, synthesis, polyphenols, tocopherol. Les antioxydants pourraient potentiellement etre utilises dans le traitement des defaillances cardiovasculaires et des processus neurodegeneratifs et il est connu que des produis chimeriques qui combinent un groupe de tete flavon-3-ol apparente a la myricetine et un groupe de queue lipophile decyle protegent les membranes des dommages oxydants, au moins aussi bien que la vitamine E. Utilisant comme produits de departs des acides trimethoxy- et tetramethoxybenzoiques obtenus par des reactions de lithiation/carboxylation, on a prepare de nouveaux flavon-3-ols hautement hydroxyles dans le noyau B, qui different ainsi des flavon-3-ols naturels et qui portent un groupe de queue lipophile decyle. Dans les cas ou on retrouve des groupes methoxy a la fois dans les positions 2- et 6- des derives de l'acide benzoique, on a prefere l'acylation directe de l'enolate par rapport au rearrangement de Baker-Venkataramn. Mots-cles : flavonol, antioxydant, synthese, polyphenols, tocopherol. [Traduit par la Redaction], Introduction Flavonoids (Fig. 1) are polyphenolic compounds produced as secondary metabolites by plants. They have attracted a great deal of attention over the years because they are found in a [...]
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- 2012
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8. Nrf2 is activated by disruption of mitochondrial thiol homeostasis but not by enhanced mitochondrial superoxide production
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Cvetko, Filip, primary, Caldwell, Stuart T., additional, Higgins, Maureen, additional, Suzuki, Takafumi, additional, Yamamoto, Masayuki, additional, Prag, Hiran A., additional, Hartley, Richard C., additional, Dinkova-Kostova, Albena T., additional, and Murphy, Michael P., additional
- Published
- 2021
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9. Enhancing the Mitochondrial Uptake of Phosphonium Cations by Carboxylic Acid Incorporation
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Pala, Laura, Senn, Hans M., Caldwell, Stuart T., Prime, Tracey A., Warrington, Stefan, Bright, Thomas P., Prag, Hiran A., Wilson, Claire, Murphy, Michael, Hartley, Richard C., Prag, Hiran [0000-0002-4753-8567], Murphy, Mike [0000-0003-1115-9618], and Apollo - University of Cambridge Repository
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mitochondria ,Chemistry ,membrane permeation ,mitochondria-targeting ,phosphonium ,membrane potential ,computational chemistry ,pH gradient - Abstract
There is considerable interest in developing drugs and probes targeted to mitochondria in order to understand and treat the many pathologies associated with mitochondrial dysfunction. The large membrane potential, negative inside, across the mitochondrial inner membrane enables delivery of molecules conjugated to lipophilic phosphonium cations to the organelle. Due to their combination of charge and hydrophobicity, quaternary triarylphosphonium cations rapidly cross biological membranes without the requirement for a carrier. Their extent of uptake is determined by the magnitude of the mitochondrial membrane potential, as described by the Nernst equation. To further enhance this uptake here we explored whether incorporation of a carboxylic acid into a quaternary triarylphosphonium cation would enhance its mitochondrial uptake in response to both the membrane potential and the mitochondrial pH gradient (alkaline inside). Accumulation of aryl propionic acid derivatives depended on both the membrane potential and the pH gradient. However, acetic or benzoic derivatives did not accumulate, due to their lowered pKa. Surprisingly, despite not being taken up by mitochondria, the phenylacetic or phenylbenzoic derivatives were not retained within mitochondria when generated within the mitochondrial matrix by hydrolysis of their cognate esters. Computational studies, supported by crystallography, showed that these molecules passed through the hydrophobic core of mitochondrial inner membrane as a neutral dimer. This finding extends our understanding of the mechanisms of membrane permeation of lipophilic cations and suggests future strategies to enhance drug and probe delivery to mitochondria.
- Published
- 2020
10. Selective disruption of mitochondrial thiol redox state in cells and in vivo
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Booty, Lee M, Gawel, Justyna M, Cvetko, Filip, Caldwell, Stuart T, Hall, Andrew R, Mulvey, John F, James, Andrew M, Hinchy, Elizabeth C, Prime, Tracy A, Arndt, Sabine, Beninca, Cristiane, Bright, Thomas P, Clatworthy, Menna R, Ferdinand, John R, Prag, Hiran A, Logan, Angela, Prudent, Julien, Krieg, Thomas, Hartley, Richard C, and Murphy, Michael P
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mitochondria ,mitochondria targeting ,thioredoxin ,glutathione ,thiol redox state ,redox signaling - Abstract
Mitochondrial glutathione (GSH) and thioredoxin (Trx) systems function independently of the rest of the cell. While maintenance of mitochondrial thiol redox state is thought vital for cell survival, this was not testable due to the difficulty of manipulating the organelle's thiol systems independently of those in other cell compartments. To overcome this constraint we modified the glutathione S-transferase substrate and Trx reductase (TrxR) inhibitor, 1-chloro-2,4-dinitrobenzene (CDNB) by conjugation to the mitochondria-targeting triphenylphosphonium cation. The result, MitoCDNB, is taken up by mitochondria where it selectively depletes the mitochondrial GSH pool, catalyzed by glutathione S-transferases, and directly inhibits mitochondrial TrxR2 and peroxiredoxin 3, a peroxidase. Importantly, MitoCDNB inactivates mitochondrial thiol redox homeostasis in isolated cells and in vivo, without affecting that of the cytosol. Consequently, MitoCDNB enables assessment of the biomedical importance of mitochondrial thiol homeostasis in reactive oxygen species production, organelle dynamics, redox signaling, and cell death in cells and in vivo.
- Published
- 2019
11. Mitochondrial oxidative stress causes insulin resistance without disrupting oxidative phosphorylation
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Fazakerley, Daniel J., Minard, Annabel Y., Krycer, James R., Thomas, Kristen C., Stöckli, Jacqueline, Harney, Dylan J., Burchfield, James G., Maghzal, Ghassan J., Caldwell, Stuart T., Hartley, Richard C., Stocker, Roland, Murphy, Michael P., James, David E., Fazakerley, Daniel [0000-0001-8241-2903], Murphy, Mike [0000-0003-1115-9618], and Apollo - University of Cambridge Repository
- Subjects
Male ,Paraquat ,insulin ,muscle ,hydrogen peroxide ,adipocyte ,Oxidative Phosphorylation ,Electron Transport ,Myoblasts ,Mice ,Oxygen Consumption ,Superoxides ,insulin resistance ,3T3-L1 Cells ,Adipocytes ,oxidative stress ,Animals ,Protein Isoforms ,superoxide ion ,Glucose Transporter Type 4 ,Herbicides ,Adenylate Kinase ,Peroxiredoxins ,adipose tissue ,Mitochondria ,Mice, Inbred C57BL ,Glucose ,Mitochondrial dysfunction - Abstract
Mitochondrial oxidative stress, mitochondrial dysfunction, or both have been implicated in insulin resistance. However, disentangling the individual roles of these processes in insulin resistance has been difficult because they often occur in tandem, and tools that selectively increase oxidant production without impairing mitochondrial respiration have been lacking. Using the dimer/monomer status of peroxiredoxin isoforms as an indicator of compartmental hydrogen peroxide burden, we provide evidence that oxidative stress is localized to mitochondria in insulin-resistant 3T3-L1 adipocytes and adipose tissue from mice. To dissociate oxidative stress from impaired oxidative phosphorylation and study whether mitochondrial oxidative stress per se can cause insulin resistance, we used mitochondria-targeted paraquat (MitoPQ) to generate superoxide within mitochondria without directly disrupting the respiratory chain. At ≤10 μm, MitoPQ specifically increased mitochondrial superoxide and hydrogen peroxide without altering mitochondrial respiration in intact cells. Under these conditions, MitoPQ impaired insulin-stimulated glucose uptake and glucose transporter 4 (GLUT4) translocation to the plasma membrane in both adipocytes and myotubes. MitoPQ recapitulated many features of insulin resistance found in other experimental models, including increased oxidants in mitochondria but not cytosol; a more profound effect on glucose transport than on other insulin-regulated processes, such as protein synthesis and lipolysis; an absence of overt defects in insulin signaling; and defective insulin- but not AMP-activated protein kinase (AMPK)-regulated GLUT4 translocation. We conclude that elevated mitochondrial oxidants rapidly impair insulin-regulated GLUT4 translocation and significantly contribute to insulin resistance and that MitoPQ is an ideal tool for studying the link between mitochondrial oxidative stress and regulated GLUT4 trafficking.
- Published
- 2018
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12. Methionine sulfoxide reductase B3 requires resolving cysteine residues for full activity and can act as a stereospecific methionine oxidase
- Author
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Cao, Zhenbo, Mitchell, Lorna, Hsia, Oliver, Scarpa, Miriam, Caldwell, Stuart T., Alfred, Arina D., Gennaris, Alexandra, Collet, Jean-Francois, Hartley, Richard C., and Bulleid, Neil J.
- Abstract
The oxidation of methionine residues in proteins occurs during oxidative stress and can lead to an alteration in protein function. The enzyme methionine sulfoxide reductase reverses this modification. Here we characterise the mammalian enzyme methionine sulfoxide reductase B3. There are two splice variants of this enzyme that differ only in their N-terminal signal sequence, which directs the protein to either the ER or mitochondria. We demonstrate here that the enzyme can complement a bacterial strain which is dependent upon methionine sulfoxide reduction for growth, that the purified recombinant protein is enzymatically active showing stereospecificity towards R -methionine sulfoxide, and identify the active site and two resolving cysteine residues. The enzyme is efficiently recycled by thioredoxin only in the presence of both resolving cysteine residues. These results show that for this isoform of methionine sulfoxide reductase, the reduction cycle most likely proceeds through a three step process. This involves an initial sulfenylation of the active site thiol followed by the formation of an intra-chain disulfide with a resolving thiol group and completed by the reduction of this disulfide by a thioredoxin-like protein to regenerate the active site thiol. Interestingly the enzyme can also act as an oxidase catalysing the stereospecific formation of R -methionine sulfoxide. This result has important implications for the role of this enzyme in the reversible modification of ER and mitochondrial proteins.
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- 2018
13. Dendron-Anchored Organocatalysts: The Asymmetric Reduction Of Imines With Trichlorosilane, Catalysed By An Amino Acid-Derived Formamide Appended To A Dendron
- Author
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Figlus, Marek, Caldwell, Stuart T., Walas, Dawid, Yesilbag, Gulen, Cooke, Graeme, Kocovsky, Pavel, Malkov, Andrei V., and Sanyal, Amitav
- Abstract
Asymmetric reduction of ketimines 1a-f with trichlorosilane can be catalysed by the Lewis-basic N-methylvaline-derived formamide anchored to a soluble dendron (11c) with good enantioselectivity (
- Published
- 2010
14. Excited State Charge Redistribution and Dynamics in the Donor-π-Acceptor Flavin Derivative ABFL
- Author
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Pauszek, Raymond F., primary, Kodali, Goutham, additional, Caldwell, Stuart T., additional, Fitzpatrick, Brian, additional, Zainalabdeen, Nada Y., additional, Cooke, Graeme, additional, Rotello, Vincent M., additional, and Stanley, Robert J., additional
- Published
- 2013
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15. ExcitedState Charge Redistribution and Dynamics inthe Donor-π-Acceptor Flavin Derivative ABFL.
- Author
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Pauszek, Raymond F., Kodali, Goutham, Caldwell, Stuart T., Fitzpatrick, Brian, Zainalabdeen, Nada Y., Cooke, Graeme, Rotello, Vincent M., and Stanley, Robert J.
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- 2013
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16. Synthesis of an azido-tagged low affinity ratiometric calcium sensor
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Caldwell, Stuart T., Cairns, Andrew G., Olson, Marnie, Chalmers, Susan, Sandison, Mairi, Mullen, William, McCarron, John G., and Hartley, Richard C.
- Subjects
QD450 ,RZ ,Organic Chemistry ,Drug Discovery ,Calcium ,BAPTA ,Biochemistry ,Fluorescence ,Thiohydantoin ,Bioorthogonal - Abstract
Changes in high localised concentrations of Ca2+ ions are fundamental to cell signalling. The synthesis of a dual excitation, ratiometric calcium ion sensor with a Kd of 90 μM, is described. It is tagged with an azido group for bioconjugation, and absorbs in the blue/green and emits in the red region of the visible spectrum with a large Stokes shift. The binding modulating nitro group is introduced to the BAPTA core prior to construction of a benzofuran-2-yl carboxaldehyde by an allylation–oxidation–cyclisation sequence, which is followed by condensation with an azido-tagged thiohydantoin. The thiohydantoin unit has to be protected with an acetoxymethyl (AM) caging group to allow CuAAC click reaction and incorporation of the KDEL peptide endoplasmic reticulum (ER) retention sequence.
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17. Photoactivated release of membrane impermeant sulfonates inside cells
- Author
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Filip Cvetko, John G. McCarron, Calum Wilson, Sean N O'Byrne, Michael P. Murphy, Stuart T. Caldwell, Richard C. Hartley, Caldwell, Stuart T [0000-0003-1604-3462], O'Byrne, Sean N [0000-0002-1880-0239], Wilson, Calum [0000-0003-2500-0632], Murphy, Michael P [0000-0003-1115-9618], McCarron, John G [0000-0002-3302-3984], Hartley, Richard C [0000-0003-1033-5405], and Apollo - University of Cambridge Repository
- Subjects
Anions ,Cell Membrane Permeability ,Cell ,010402 general chemistry ,01 natural sciences ,Catalysis ,Phosphates ,chemistry.chemical_compound ,Coumarins ,Materials Chemistry ,medicine ,Humans ,QD ,010405 organic chemistry ,Rhodamines ,fungi ,Metals and Alloys ,food and beverages ,General Chemistry ,Photochemical Processes ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Chemistry ,Sulfonate ,Membrane ,medicine.anatomical_structure ,chemistry ,Ceramics and Composites ,Biophysics ,Sulfonic Acids ,HeLa Cells - Abstract
Photouncaging delivers compounds with high spatial and temporal control to induce or inhibit biological processes but the released compounds may diffuse out. We here demonstrate that sulfonate anions can be photocaged so that a membrane impermeable compound can enter cells, be uncaged by photoirradiation and trapped within the cell., Photocaged sulfonate delivers membrane impermeant compounds to cells.
- Published
- 2021
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18. Rapid and selective generation of H 2 S within mitochondria protects against cardiac ischemia-reperfusion injury.
- Author
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Miljkovic JL, Burger N, Gawel JM, Mulvey JF, Norman AAI, Nishimura T, Tsujihata Y, Logan A, Sauchanka O, Caldwell ST, Morris JL, Prime TA, Warrington S, Prudent J, Bates GR, Aksentijević D, Prag HA, James AM, Krieg T, Hartley RC, and Murphy MP
- Abstract
Mitochondria-targeted H
2 S donors are thought to protect against acute ischemia-reperfusion (IR) injury by releasing H2 S that decreases oxidative damage. However, the rate of H2 S release by current donors is too slow to be effective upon administration following reperfusion. To overcome this limitation here we develop a mitochondria-targeted agent, MitoPerSulf that very rapidly releases H2 S within mitochondria. MitoPerSulf is quickly taken up by mitochondria, where it reacts with endogenous thiols to generate a persulfide intermediate that releases H2 S. MitoPerSulf is acutely protective against cardiac IR injury in mice, due to the acute generation of H2 S that inhibits respiration at cytochrome c oxidase thereby preventing mitochondrial superoxide production by lowering the membrane potential. Mitochondria-targeted agents that rapidly generate H2 S are a new class of therapy for the acute treatment of IR injury., (Copyright © 2022 The Authors. Published by Elsevier B.V. All rights reserved.)- Published
- 2022
- Full Text
- View/download PDF
19. Mitochondrial oxidative stress causes insulin resistance without disrupting oxidative phosphorylation.
- Author
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Fazakerley DJ, Minard AY, Krycer JR, Thomas KC, Stöckli J, Harney DJ, Burchfield JG, Maghzal GJ, Caldwell ST, Hartley RC, Stocker R, Murphy MP, and James DE
- Subjects
- 3T3-L1 Cells, Adenylate Kinase metabolism, Adipocytes metabolism, Animals, Electron Transport drug effects, Glucose metabolism, Glucose Transporter Type 4 metabolism, Herbicides pharmacology, Hydrogen Peroxide metabolism, Insulin metabolism, Male, Mice, Mice, Inbred C57BL, Mitochondria drug effects, Myoblasts metabolism, Oxygen Consumption drug effects, Paraquat toxicity, Peroxiredoxins metabolism, Protein Isoforms metabolism, Superoxides metabolism, Insulin Resistance, Mitochondria metabolism, Oxidative Phosphorylation
- Abstract
Mitochondrial oxidative stress, mitochondrial dysfunction, or both have been implicated in insulin resistance. However, disentangling the individual roles of these processes in insulin resistance has been difficult because they often occur in tandem, and tools that selectively increase oxidant production without impairing mitochondrial respiration have been lacking. Using the dimer/monomer status of peroxiredoxin isoforms as an indicator of compartmental hydrogen peroxide burden, we provide evidence that oxidative stress is localized to mitochondria in insulin-resistant 3T3-L1 adipocytes and adipose tissue from mice. To dissociate oxidative stress from impaired oxidative phosphorylation and study whether mitochondrial oxidative stress per se can cause insulin resistance, we used mitochondria-targeted paraquat (MitoPQ) to generate superoxide within mitochondria without directly disrupting the respiratory chain. At ≤10 μm, MitoPQ specifically increased mitochondrial superoxide and hydrogen peroxide without altering mitochondrial respiration in intact cells. Under these conditions, MitoPQ impaired insulin-stimulated glucose uptake and glucose transporter 4 (GLUT4) translocation to the plasma membrane in both adipocytes and myotubes. MitoPQ recapitulated many features of insulin resistance found in other experimental models, including increased oxidants in mitochondria but not cytosol; a more profound effect on glucose transport than on other insulin-regulated processes, such as protein synthesis and lipolysis; an absence of overt defects in insulin signaling; and defective insulin- but not AMP-activated protein kinase (AMPK)-regulated GLUT4 translocation. We conclude that elevated mitochondrial oxidants rapidly impair insulin-regulated GLUT4 translocation and significantly contribute to insulin resistance and that MitoPQ is an ideal tool for studying the link between mitochondrial oxidative stress and regulated GLUT4 trafficking., (© 2018 by The American Society for Biochemistry and Molecular Biology, Inc.)
- Published
- 2018
- Full Text
- View/download PDF
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