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Ghorpade M, Soppina V, Kanvah S. Substitution Effects on Subcellular Organelle Localization in Live-cell Imaging. Chembiochem 2024; 25:e202400273. [PMID: 38924297 DOI: 10.1002/cbic.202400273] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2024] [Revised: 06/24/2024] [Accepted: 06/24/2024] [Indexed: 06/28/2024]
Abstract
A series of D-π-A indole-containing fluorescent probes were developed, followed by an investigation of their photophysical properties and compounds' suitability for subcellular imaging in living cells. We demonstrate that the preference for mitochondrial localization was lost when morpholine was substituted, resulting in the accumulation of the molecule in the lysosomes. However, interestingly, the presence of a nitro group led to their localization within the lipid droplets despite the presence of the morpholine pendant. We also showcase the probes' sensitivity to pH, the influence of added chloroquine, and the temperature response on the changes in fluorescence intensity within lysosomes. The design of the probes with strong intramolecular charge transfer and substantial Stokes shift could facilitate extensive application in various cellular lysosomal models and contribute to a better understanding of the mechanisms involved in stimuli-responsive diseases.
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Affiliation(s)
- Mohini Ghorpade
- Department of Chemistry, Indian Institute of Technology Gandhinagar, Palaj, Gandhinagar, 382055
| | - Virupakshi Soppina
- Department of Biological Engineering, Indian Institute of Technology Gandhinagar, Palaj, Gandhinagar, 382055
| | - Sriram Kanvah
- Department of Chemistry, Indian Institute of Technology Gandhinagar, Palaj, Gandhinagar, 382055
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2
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Saponjic J, Mejías R, Nikolovski N, Dragic M, Canak A, Papoutsopoulou S, Gürsoy-Özdemir Y, Fladmark KE, Ntavaroukas P, Bayar Muluk N, Zeljkovic Jovanovic M, Fontán-Lozano Á, Comi C, Marino F. Experimental Models to Study Immune Dysfunction in the Pathogenesis of Parkinson's Disease. Int J Mol Sci 2024; 25:4330. [PMID: 38673915 PMCID: PMC11050170 DOI: 10.3390/ijms25084330] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2024] [Revised: 03/25/2024] [Accepted: 03/26/2024] [Indexed: 04/28/2024] Open
Abstract
Parkinson's disease (PD) is a chronic, age-related, progressive multisystem disease associated with neuroinflammation and immune dysfunction. This review discusses the methodological approaches used to study the changes in central and peripheral immunity in PD, the advantages and limitations of the techniques, and their applicability to humans. Although a single animal model cannot replicate all pathological features of the human disease, neuroinflammation is present in most animal models of PD and plays a critical role in understanding the involvement of the immune system (IS) in the pathogenesis of PD. The IS and its interactions with different cell types in the central nervous system (CNS) play an important role in the pathogenesis of PD. Even though culture models do not fully reflect the complexity of disease progression, they are limited in their ability to mimic long-term effects and need validation through in vivo studies. They are an indispensable tool for understanding the interplay between the IS and the pathogenesis of this disease. Understanding the immune-mediated mechanisms may lead to potential therapeutic targets for the treatment of PD. We believe that the development of methodological guidelines for experiments with animal models and PD patients is crucial to ensure the validity and consistency of the results.
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Affiliation(s)
- Jasna Saponjic
- Department of Neurobiology, Institute of Biological Research “Sinisa Stankovic”, National Institute of the Republic of Serbia, University of Belgrade, 11108 Belgrade, Serbia
| | - Rebeca Mejías
- Department of Physiology, School of Biology, University of Seville, 41012 Seville, Spain; (R.M.); (Á.F.-L.)
- Instituto de Biomedicina de Sevilla, IBiS, Hospital Universitario Virgen del Rocío, CSIC, Universidad de Sevilla, 41013 Seville, Spain
| | - Neda Nikolovski
- Department of Immunology, Institute for Biological Research “Siniša Stanković”, National Institute of the Republic of Serbia, University of Belgrade, 11108 Belgrade, Serbia;
| | - Milorad Dragic
- Laboratory for Neurobiology, Department for General Physiology and Biophysics, Faculty of Biology, University of Belgrade, 11000 Belgrade, Serbia; (M.D.); (M.Z.J.)
- Department of Molecular Biology and Endocrinology, Vinca Institute of Nuclear Sciences–National Institute of the Republic of Serbia, University of Belgrade, 11351 Belgrade, Serbia
| | - Asuman Canak
- Department of Medical Services and Techniques, Vocational School of Health Services, Recep Tayyip Erdogan University, Rize 53100, Turkey;
| | - Stamatia Papoutsopoulou
- Department of Biochemistry and Biotechnology, Faculty of Health Sciences, University of Thessaly, Biopolis, 41500 Larisa, Greece; (S.P.); (P.N.)
| | | | - Kari E. Fladmark
- Department of Biological Science, University of Bergen, 5020 Bergen, Norway;
| | - Panagiotis Ntavaroukas
- Department of Biochemistry and Biotechnology, Faculty of Health Sciences, University of Thessaly, Biopolis, 41500 Larisa, Greece; (S.P.); (P.N.)
| | - Nuray Bayar Muluk
- Department of Otorhinolaryngology, Faculty of Medicine, Kirikkale University, Kirikkale 71450, Turkey;
| | - Milica Zeljkovic Jovanovic
- Laboratory for Neurobiology, Department for General Physiology and Biophysics, Faculty of Biology, University of Belgrade, 11000 Belgrade, Serbia; (M.D.); (M.Z.J.)
| | - Ángela Fontán-Lozano
- Department of Physiology, School of Biology, University of Seville, 41012 Seville, Spain; (R.M.); (Á.F.-L.)
- Instituto de Biomedicina de Sevilla, IBiS, Hospital Universitario Virgen del Rocío, CSIC, Universidad de Sevilla, 41013 Seville, Spain
| | - Cristoforo Comi
- Neurology Unit, Department of Translational Medicine, S. Andrea Hospital, University of Piemonte Orientale, 13100 Vercelli, Italy;
| | - Franca Marino
- Center for Research in Medical Pharmacology, School of Medicine, University of Insubria, 21100 Varese, Italy;
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3
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Uno S, Harkiss AH, Chowdhury R, Caldwell ST, Prime TA, James AM, Gallagher B, Prudent J, Hartley RC, Murphy MP. Incorporating a Polyethyleneglycol Linker to Enhance the Hydrophilicity of Mitochondria-Targeted Triphenylphosphonium Constructs. Chembiochem 2023; 24:e202200774. [PMID: 36917207 PMCID: PMC10946768 DOI: 10.1002/cbic.202200774] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 02/22/2023] [Accepted: 03/14/2023] [Indexed: 03/15/2023]
Abstract
The targeting of bioactive molecules and probes to mitochondria can be achieved by coupling to the lipophilic triphenyl phosphonium (TPP) cation, which accumulates several hundred-fold within mitochondria in response to the mitochondrial membrane potential (Δψm ). Typically, a simple alkane links the TPP to its "cargo", increasing overall hydrophobicity. As it would be beneficial to enhance the water solubility of mitochondria-targeted compounds we explored the effects of replacing the alkyl linker with a polyethylene glycol (PEG). We found that the use of PEG led to compounds that were readily taken up by isolated mitochondria and by mitochondria inside cells. Within mitochondria the PEG linker greatly decreased adsorption of the TPP constructs to the matrix-facing face of the mitochondrial inner membrane. These findings will allow the distribution of mitochondria-targeted TPP compounds within mitochondria to be fine-tuned.
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Affiliation(s)
- Shinpei Uno
- MRC Mitochondrial Biology UnitUniversity of CambridgeCambridgeCB2 0XYUK
| | | | - Roy Chowdhury
- MRC Mitochondrial Biology UnitUniversity of CambridgeCambridgeCB2 0XYUK
| | | | - Tracy A. Prime
- MRC Mitochondrial Biology UnitUniversity of CambridgeCambridgeCB2 0XYUK
| | - Andrew M. James
- MRC Mitochondrial Biology UnitUniversity of CambridgeCambridgeCB2 0XYUK
| | | | - Julien Prudent
- MRC Mitochondrial Biology UnitUniversity of CambridgeCambridgeCB2 0XYUK
| | | | - Michael P. Murphy
- MRC Mitochondrial Biology UnitUniversity of CambridgeCambridgeCB2 0XYUK
- Department of MedicineUniversity of CambridgeCambridgeCB2 0QQUK
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4
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Rokitskaya TI, Aleksandrova EV, Korshunova GA, Khailova LS, Tashlitsky VN, Luzhkov VB, Antonenko YN. Membrane Permeability of Modified Butyltriphenylphosphonium Cations. J Phys Chem B 2022; 126:412-422. [PMID: 34994564 DOI: 10.1021/acs.jpcb.1c08135] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The alkyltriphenylphosphonium (TPP) group is the most widely used vector targeted to mitochondria. Previously, the length of the alkyl linker was varied as well as structural modifications in the TPP phenyl rings to obtain the optimal therapeutic effect of a pharmacophore conjugated with a lipophilic cation. In the present work, we synthesized butyltriphenylphosphonium cations halogenated and methylated in phenyl rings (C4TPP-X) and measured electrical current through a planar lipid bilayer in the presence of C4TPP-X. The permeability of C4TPP-X varied in the range of 6 orders of magnitude and correlates well with the previously measured translocation rate constant for dodecyltriphenylphosphonium analogues. The partition coefficient of the butyltriphenylphosphonium analogues obtained by calculating the difference in the free energy of cation solvation in water and octane using quantum chemical methods correlates well with the permeability values. Using an ion-selective electrode, a lower degree of accumulation of analogues with halogenated phenyl groups was found on isolated mitochondria of rat liver, which is in agreement with their permeability decrease. Our results indicate the translocation of the butyltriphenylphosphonium cations across the hydrophobic membrane core as rate-limiting stage in the permeability process rather than their binding/release to/from the membrane.
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Affiliation(s)
- Tatyana I Rokitskaya
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119991, Russia
| | | | - Galina A Korshunova
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119991, Russia
| | - Ljudmila S Khailova
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119991, Russia
| | - Vadim N Tashlitsky
- Department of Chemistry, Lomonosov Moscow State University, Moscow 119991, Russia
| | - Victor B Luzhkov
- Department of Kinetics of Chemical and Biological Processes, Institute of Problems of Chemical Physics, Russian Academy of Sciences, acad. Semenov av. 1, Chernogolovka, Moscow Region 142432, Russia.,Department of Fundamental Physical and Chemical Engineering, Lomonosov Moscow State University, Moscow 119991, Russia
| | - Yuri N Antonenko
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119991, Russia
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O’Hara D, Davis GM, Adlesic NA, Hayes JM, Davey GP. Dichloroacetate Stabilizes Mitochondrial Fusion Dynamics in Models of Neurodegeneration. Front Mol Neurosci 2019; 12:219. [PMID: 31619961 PMCID: PMC6759677 DOI: 10.3389/fnmol.2019.00219] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2019] [Accepted: 08/29/2019] [Indexed: 12/16/2022] Open
Abstract
Mitochondrial dysfunction is a recognized hallmark of neurodegenerative diseases and abnormal mitochondrial fusion-fission dynamics have been implicated in the pathogenesis of neurodegenerative disorders. This study characterizes the effects of metabolic flux inhibitors and activators on mitochondrial fusion dynamics in the neuronal cell culture model of differentiated PC12 cells. Using a real time confocal microscopy assay, it was found that the carnitine palmitoyltransferase I (CPTI) inhibitor, etomoxir, reduced mitochondrial fusion dynamics in a time-dependent manner. Etomoxir also decreased JO2, ΔΨm and reactive oxygen species (ROS) production rates. The mitochondrial pyruvate carrier (MPC) inhibitor, UK5099, reduced fusion dynamics and in combination with etomoxir these inhibitory effects were amplified. Use of the pyruvate dehydrogenase (PDH) kinase inhibitor dichloroacetate, which is known to increase metabolic flux through PDH, reversed the etomoxir-induced effects on fusion dynamics, JO2, ΔΨm but not ROS production rates. Dichloroacetate also partially reversed inhibition of mitochondrial fusion dynamics caused by the parkinsonian-inducing neurotoxin, MPP+. These results suggest that dichloroacetate-induced activation of metabolic flux in the mitochondrion may be a mechanism to restore normal mitochondrial fusion-fission dynamics in metabolically challenged cells.
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Affiliation(s)
| | | | | | | | - Gavin P. Davey
- School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin 2, Ireland
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Yagishita F, Tanigawa JI, Nii C, Tabata A, Nagamune H, Takanari H, Imada Y, Kawamura Y. Fluorescent Imidazo[1,5- a]pyridinium Salt for a Potential Cancer Therapy Agent. ACS Med Chem Lett 2019; 10:1110-1114. [PMID: 31417665 DOI: 10.1021/acsmedchemlett.9b00034] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Accepted: 07/24/2019] [Indexed: 01/09/2023] Open
Abstract
N,N'-Dimethylated imidazo[1,5-a]pyridinium salt having good water solubility and exhibiting fluorescence emission was found to work as not only a bioimaging agent but also a therapeutic agent under UVA-LED irradiation conditions. Because the continuous UVA-LED irradiation to HeLa cells stained by the synthesized salt resulted in the cell death due to the mitochondrial damage, the salt has a potential application as photodynamic therapy agent against tumor cells.
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Affiliation(s)
- Fumitoshi Yagishita
- Department of Applied Chemistry, Graduate School of Technology, Industrial and Social Sciences, Tokushima University, Tokushima 770-8506, Japan
- Institute of Post-LED Photonics, Tokushima University, Tokushima 770-8506, Japan
| | - Jun-ichi Tanigawa
- Department of Applied Chemistry, Graduate School of Technology, Industrial and Social Sciences, Tokushima University, Tokushima 770-8506, Japan
| | - Chiho Nii
- Department of Applied Chemistry, Graduate School of Technology, Industrial and Social Sciences, Tokushima University, Tokushima 770-8506, Japan
| | - Atsushi Tabata
- Department of Bioscience and Bioindustry, Graduate School of Technology, Industrial and Social Sciences, Tokushima University, Tokushima 770-8513, Japan
| | - Hideaki Nagamune
- Department of Bioscience and Bioindustry, Graduate School of Technology, Industrial and Social Sciences, Tokushima University, Tokushima 770-8513, Japan
| | - Hiroki Takanari
- Department of Interdisciplinary Researches for Medicine and Photonics, Institute of Post-LED Photonics, Tokushima University, Tokushima 770-8503, Japan
| | - Yasushi Imada
- Department of Applied Chemistry, Graduate School of Technology, Industrial and Social Sciences, Tokushima University, Tokushima 770-8506, Japan
| | - Yasuhiko Kawamura
- Department of Applied Chemistry, Graduate School of Technology, Industrial and Social Sciences, Tokushima University, Tokushima 770-8506, Japan
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Mapa MST, Le VQ, Wimalasena K. Characteristics of the mitochondrial and cellular uptake of MPP+, as probed by the fluorescent mimic, 4'I-MPP. PLoS One 2018; 13:e0197946. [PMID: 30138351 PMCID: PMC6107127 DOI: 10.1371/journal.pone.0197946] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Accepted: 08/06/2018] [Indexed: 11/24/2022] Open
Abstract
The discovery that 1-methyl-4-phenylpyridinium (MPP+) selectively destroys dopaminergic neurons and causes Parkinson’s disease (PD) symptoms in mammals has strengthened the environmental hypothesis of PD. The current model for the dopaminergic toxicity of MPP+ is centered on its uptake into dopaminergic neurons, accumulation into the mitochondria, inhibition of the complex-I leading to ATP depletion, increased reactive oxygen species (ROS) production, and apoptotic cell death. However, some aspects of this mechanism and the details of the cellular and mitochondrial accumulation of MPP+ are still poorly understood. The aim of this study was to characterize a structural and functional MPP+ mimic which is suitable to study the cellular distribution and mitochondrial uptake of MPP+ in live cells and use it to identify the molecular details of these processes to advance the understanding of the mechanism of the selective dopaminergic toxicity of MPP+. Here we report the characterization of the fluorescent MPP+ derivative, 1-methyl-4-(4'-iodophenyl)pyridinium (4'I-MPP+), as a suitable candidate for this purpose. Using this novel probe, we show that cytosolic/mitochondrial Ca2+ play a critical role through the sodium-calcium exchanger (NCX) in the mitochondrial and cellular accumulation of MPP+ suggesting for the first time that MPP+ and related mitochondrial toxins may also exert their toxic effects through the perturbation of Ca2+ homeostasis in dopaminergic cells. We also found that the specific mitochondrial NCX (mNCX) inhibitors protect dopaminergic cells from the MPP+ and 4'I-MPP+ toxicity, most likely through the inhibition of the mitochondrial uptake, which could potentially be exploited for the development of pharmacological agents to protect the central nervous system (CNS) dopaminergic neurons from PD-causing environmental toxins.
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Affiliation(s)
- Mapa S T Mapa
- Department of Chemistry, Wichita State University, Wichita, Kansas, United States of America
| | - Viet Q Le
- Department of Chemistry, Wichita State University, Wichita, Kansas, United States of America
| | - Kandatege Wimalasena
- Department of Chemistry, Wichita State University, Wichita, Kansas, United States of America
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8
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Datta S, He G, Tomilov A, Sahdeo S, Denison MS, Cortopassi G. In Vitro Evaluation of Mitochondrial Function and Estrogen Signaling in Cell Lines Exposed to the Antiseptic Cetylpyridinium Chloride. ENVIRONMENTAL HEALTH PERSPECTIVES 2017; 125:087015. [PMID: 28885978 PMCID: PMC5783672 DOI: 10.1289/ehp1404] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Revised: 05/04/2017] [Accepted: 05/09/2017] [Indexed: 05/15/2023]
Abstract
BACKGROUND Quaternary ammonium salts (QUATS), such as cetylpyridinium chloride (CPC) and benzalkonium chloride (BAK), are frequently used in antiseptic formulations, including toothpastes, mouthwashes, lozenges, throat and nasal sprays, and as biocides. Although in a recent ruling, the U.S. Food and Drug Administration (FDA) banned CPC from certain products and requested more data on BAK's efficacy and safety profile, QUATS, in general, and CPC and BAK, in particular, continue to be used in personal health care, food, and pharmaceutical and cleaning industries. OBJECTIVES We aimed to assess CPC's effects on mitochondrial toxicity and endocrine disruption in vitro. METHOD Mitochondrial O2 consumption and adenosine triphosphate (ATP) synthesis rates of osteosarcoma cybrid cells were measured before and after CPC and BAK treatment. Antiestrogenic effects of the compounds were measured by a luciferase-based assay using recombinant human breast carcinoma cells (VM7Luc4E2, ERalpha-positive). RESULTS CPC inhibited both mitochondrial O2 consumption [half maximal inhibitory concentration (IC50): 3.8μM] and ATP synthesis (IC50: 0.9μM), and additional findings supported inhibition of mitochondrial complex 1 as the underlying mechanism for these effects. In addition, CPC showed concentration-dependent antiestrogenic activity half maximal effective concentration [(EC50): 4.5μM)]. BAK, another antimicrobial QUATS that is structurally similar to CPC, and the pesticide rotenone, a known complex 1 inhibitor, also showed mitochondrial inhibitory and antiestrogenic effects. In all three cases, there was overlap of the antiestrogenic activity with the mitochondrial inhibitory activity. CONCLUSIONS Mitochondrial inhibition in vitro occurred at a CPC concentration that may be relevant to human exposures. The antiestrogenic activity of CPC, BAK, rotenone, and triclosan may be related to their mitochondrial inhibitory activity. Our findings support the need for additional research on the mitochondrial inhibitory and antiestrogenic effects of QUATS, including CPC and BAK. https://doi.org/10.1289/EHP1404.
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Affiliation(s)
- Sandipan Datta
- Department of Molecular Bioscience, School of Veterinary Medicine, University of California , Davis, Davis, California, USA
| | - Guochun He
- Department of Environmental Toxicology, University of California , Davis, Davis, California, USA
| | - Alexey Tomilov
- Department of Molecular Bioscience, School of Veterinary Medicine, University of California , Davis, Davis, California, USA
| | - Sunil Sahdeo
- Department of Molecular Bioscience, School of Veterinary Medicine, University of California , Davis, Davis, California, USA
| | - Michael S Denison
- Department of Environmental Toxicology, University of California , Davis, Davis, California, USA
| | - Gino Cortopassi
- Department of Molecular Bioscience, School of Veterinary Medicine, University of California , Davis, Davis, California, USA
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Zielonka J, Sikora A, Hardy M, Ouari O, Vasquez-Vivar J, Cheng G, Lopez M, Kalyanaraman B. Mitochondria-Targeted Triphenylphosphonium-Based Compounds: Syntheses, Mechanisms of Action, and Therapeutic and Diagnostic Applications. Chem Rev 2017; 117:10043-10120. [PMID: 28654243 PMCID: PMC5611849 DOI: 10.1021/acs.chemrev.7b00042] [Citation(s) in RCA: 966] [Impact Index Per Article: 138.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Mitochondria are recognized as one of the most important targets for new drug design in cancer, cardiovascular, and neurological diseases. Currently, the most effective way to deliver drugs specifically to mitochondria is by covalent linking a lipophilic cation such as an alkyltriphenylphosphonium moiety to a pharmacophore of interest. Other delocalized lipophilic cations, such as rhodamine, natural and synthetic mitochondria-targeting peptides, and nanoparticle vehicles, have also been used for mitochondrial delivery of small molecules. Depending on the approach used, and the cell and mitochondrial membrane potentials, more than 1000-fold higher mitochondrial concentration can be achieved. Mitochondrial targeting has been developed to study mitochondrial physiology and dysfunction and the interaction between mitochondria and other subcellular organelles and for treatment of a variety of diseases such as neurodegeneration and cancer. In this Review, we discuss efforts to target small-molecule compounds to mitochondria for probing mitochondria function, as diagnostic tools and potential therapeutics. We describe the physicochemical basis for mitochondrial accumulation of lipophilic cations, synthetic chemistry strategies to target compounds to mitochondria, mitochondrial probes, and sensors, and examples of mitochondrial targeting of bioactive compounds. Finally, we review published attempts to apply mitochondria-targeted agents for the treatment of cancer and neurodegenerative diseases.
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Affiliation(s)
- Jacek Zielonka
- Department of Biophysics, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, United States
- Free Radical Research Center, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, United States
- Cancer Center, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, United States
| | - Adam Sikora
- Institute of Applied Radiation Chemistry, Lodz University of Technology, ul. Wroblewskiego 15, 93-590 Lodz, Poland
| | - Micael Hardy
- Aix Marseille Univ, CNRS, ICR, UMR 7273, 13013 Marseille, France
| | - Olivier Ouari
- Aix Marseille Univ, CNRS, ICR, UMR 7273, 13013 Marseille, France
| | - Jeannette Vasquez-Vivar
- Department of Biophysics, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, United States
- Free Radical Research Center, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, United States
| | - Gang Cheng
- Department of Biophysics, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, United States
- Free Radical Research Center, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, United States
| | - Marcos Lopez
- Translational Biomedical Research Group, Biotechnology Laboratories, Cardiovascular Foundation of Colombia, Carrera 5a No. 6-33, Floridablanca, Santander, Colombia, 681003
- Graduate Program of Biomedical Sciences, Faculty of Health, Universidad del Valle, Calle 4B No. 36-00, Cali, Colombia, 760032
| | - Balaraman Kalyanaraman
- Department of Biophysics, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, United States
- Free Radical Research Center, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, United States
- Cancer Center, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, United States
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Wimalasena K. Current Status, Gaps, and Weaknesses of the Mechanism of Selective Dopaminergic Toxicity of MPTP/MPP +. ADVANCES IN MOLECULAR TOXICOLOGY 2017. [DOI: 10.1016/b978-0-12-812522-9.00003-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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11
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Rokitskaya TI, Murphy MP, Skulachev VP, Antonenko YN. Ubiquinol and plastoquinol triphenylphosphonium conjugates can carry electrons through phospholipid membranes. Bioelectrochemistry 2016; 111:23-30. [DOI: 10.1016/j.bioelechem.2016.04.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Revised: 04/26/2016] [Accepted: 04/26/2016] [Indexed: 11/16/2022]
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12
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Antonenko YN, Nechaeva NL, Baksheeva VE, Rokitskaya TI, Plotnikov EY, Kotova EA, Zorov DB. Intramitochondrial accumulation of cationic Atto520-biotin proceeds via voltage-dependent slow permeation through lipid membrane. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1848:1277-84. [PMID: 25753112 DOI: 10.1016/j.bbamem.2015.02.028] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2015] [Revised: 02/24/2015] [Accepted: 02/27/2015] [Indexed: 01/23/2023]
Abstract
Conjugation to penetrating cations is a general approach for intramitochondrial delivery of physiologically active compounds, supported by a high membrane potential of mitochondria having negative sign on the matrix side. By using fluorescence correlation spectroscopy, we found here that Atto520-biotin, a conjugate of a fluorescent cationic rhodamine-based dye with the membrane-impermeable vitamin biotin, accumulated in energized mitochondria in contrast to biotin-rhodamine 110. The energy-dependent uptake of Atto520-biotin by mitochondria, being slower than that of the conventional mitochondrial dye tetramethyl-rhodamine ethyl ester, was enhanced by the hydrophobic anion tetraphenylborate (TPB). Atto520-biotin also exhibited accumulation in liposomes driven by membrane potential resulting from potassium ion gradient in the presence valinomycin. The induction of electrical current across planar bilayer lipid membrane by Atto520-biotin proved the ability of the compound to permeate through lipid membrane in a cationic form. Atto520-biotin stained mitochondria in a culture of L929 cells, and the staining was enhanced in the presence of TPB. Therefore, the fluorescent Atto520 moiety can serve as a vehicle for intramitochondrial delivery of hydrophilic drugs. Of importance for biotin-streptavidin technology, binding of Atto520-biotin to streptavidin was found to cause quenching of its fluorescence similar to the case of fluorescein-4-biotin.
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Affiliation(s)
- Yuri N Antonenko
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russian Federation.
| | - Natalya L Nechaeva
- Department of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow, Russian Federation
| | - Victoria E Baksheeva
- Department of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow, Russian Federation
| | - Tatyana I Rokitskaya
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russian Federation
| | - Egor Y Plotnikov
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russian Federation
| | - Elena A Kotova
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russian Federation
| | - Dmitry B Zorov
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russian Federation
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Sharpe MA, Han J, Baskin AM, Baskin DS. Design and synthesis of a MAO-B-selectively activated prodrug based on MPTP: a mitochondria-targeting chemotherapeutic agent for treatment of human malignant gliomas. ChemMedChem 2015; 10:621-8. [PMID: 25677185 DOI: 10.1002/cmdc.201402562] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2014] [Indexed: 01/04/2023]
Abstract
Malignant gliomas, including glioblastomas, are extremely difficult to treat. The median survival for glioblastoma patients with optimal therapeutic intervention is 15 months. We developed a novel MAO-B-selectively activated prodrug, N,N-bis(2-chloroethyl)-2-(1-methyl-1,2,3,6-tetrahydropyridin-4-yl)propanamide (MP-MUS), for the treatment of gliomas based on 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). The design of neutral MP-MUS involved the use of a seeker molecule capable of binding to mitochondrial MAO-B, which is up-regulated ≥fourfold in glioma cells. Once the binding occurs, MP-MUS is converted into a positively charged moiety, P(+) -MUS, which accumulates inside mitochondria at a theoretical maximal value of 1000:1 gradient. The LD50 of MP-MUS against glioma cells is 75 μM, which is two- to threefold more potent than temozolomide, a primary drug for gliomas. Importantly, MP-MUS was found to be selectively toxic toward glioma cells. In the concentration range of 150-180 μM MP-MUS killed 90-95 % of glioma cells, but stimulated the growth of normal human astrocytes. Moreover, maturation of MP-MUS is highly dependent on MAO-B, and inhibition of MAO-B activity with selegiline protected human glioma cells from apoptosis.
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Affiliation(s)
- Martyn A Sharpe
- Kenneth R. Peak Brain and Pituitary Tumor Center, Department of Neurological Surgery, Neurological Institute, Houston Methodist Hospital, Weill Cornell Medical College of Cornell University, 6565 Fannin Street, Houston, TX, 77030 (USA)
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Prime TA, Forkink M, Logan A, Finichiu PG, McLachlan J, Li Pun PB, Koopman WJH, Larsen L, Latter MJ, Smith RAJ, Murphy MP. A ratiometric fluorescent probe for assessing mitochondrial phospholipid peroxidation within living cells. Free Radic Biol Med 2012; 53:544-53. [PMID: 22659314 DOI: 10.1016/j.freeradbiomed.2012.05.033] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/24/2012] [Revised: 05/22/2012] [Accepted: 05/23/2012] [Indexed: 01/02/2023]
Abstract
Mitochondrial oxidative damage contributes to a wide range of pathologies, and lipid peroxidation of the mitochondrial inner membrane is a major component of this disruption. However, despite its importance, there are no methods to assess mitochondrial lipid peroxidation within cells specifically. To address this unmet need we have developed a ratiometric, fluorescent, mitochondria-targeted lipid peroxidation probe, MitoPerOx. This compound is derived from the C11-BODIPY(581/591) probe, which contains a boron dipyromethane difluoride (BODIPY) fluorophore conjugated via a dienyl link to a phenyl group. In response to lipid peroxidation the fluorescence emission maximum shifts from ∼590 to ∼520nm. To target this probe to the matrix-facing surface of the mitochondrial inner membrane we attached a triphenylphosphonium lipophilic cation, which leads to its selective uptake into mitochondria in cells, driven by the mitochondrial membrane potential. Here we report on the development and characterization of MitoPerOx. We found that MitoPerOx was taken up very rapidly into mitochondria within cells, where it responded to changes in mitochondrial lipid peroxidation that could be measured by fluorimetry, confocal microscopy, and epifluorescence live cell imaging. Importantly, the peroxidation-sensitive change in fluorescence at 520nm relative to that at 590nm enabled the use of the probe as a ratiometric fluorescent probe, greatly facilitating assessment of mitochondrial lipid peroxidation in cells.
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Affiliation(s)
- Tracy A Prime
- MRC Mitochondrial Biology Unit, Wellcome Trust/MRC Building, Cambridge, UK
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15
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Neurotoxin-based models of Parkinson's disease. Neuroscience 2012; 211:51-76. [DOI: 10.1016/j.neuroscience.2011.10.057] [Citation(s) in RCA: 360] [Impact Index Per Article: 30.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2011] [Revised: 10/27/2011] [Accepted: 10/28/2011] [Indexed: 12/21/2022]
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Abstract
SIGNIFICANCE Parkinson's disease (PD) is a neurodegenerative disorder characterized, in part, by the progressive and selective loss of dopaminergic neuron cell bodies within the substantia nigra pars compacta (SNpc) and the associated deficiency of the neurotransmitter dopamine (DA) in the striatum, which gives rise to the typical motor symptoms of PD. The mechanisms that contribute to the induction and progressive cell death of dopaminergic neurons in PD are multi-faceted and remain incompletely understood. Data from epidemiological studies in humans and molecular studies in genetic, as well as toxin-induced animal models of parkinsonism, indicate that mitochondrial dysfunction occurs early in the pathogenesis of both familial and idiopathic PD. In this review, we provide an overview of toxin models of mitochondrial dysfunction in experimental Parkinson's disease and discuss mitochondrial mechanisms of neurotoxicity. RECENT ADVANCES A new toxin model using the mitochondrial toxin trichloroethylene was recently described and novel methods, such as intranasal exposure to toxins, have been explored. Additionally, recent research conducted in toxin models of parkinsonism provides an emerging emphasis on extranigral aspects of PD pathology. CRITICAL ISSUES Unfortunately, none of the existing animal models of experimental PD completely mimics the etiology, progression, and pathology of human PD. FUTURE DIRECTIONS Continued efforts to optimize established animal models of parkinsonism, as well as the development and characterization of new animal models are essential, as there still remains a disconnect in terms of translating mechanistic observations in animal models of experimental PD into bona fide disease-modifying therapeutics for human PD patients.
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Affiliation(s)
- Terina N Martinez
- Pittsburgh Institute for Neurodegenerative Diseases, Department of Neurology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
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Zheng N, Tsai HN, Zhang X, Rosania GR. The subcellular distribution of small molecules: from pharmacokinetics to synthetic biology. Mol Pharm 2011; 8:1619-28. [PMID: 21805990 DOI: 10.1021/mp200092v] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The systemic pharmacokinetics and pharmacodynamics of small molecules are determined by subcellular transport phenomena. Although approaches used to study the subcellular distribution of small molecules have gradually evolved over the past several decades, experimental analysis and prediction of cellular pharmacokinetics remains a challenge. In this review, we survey the progress of subcellular distribution research since the 1960s, with a focus on the advantages, disadvantages and limitations of the various experimental techniques. Critical review of the existing body of knowledge points to many opportunities to advance the rational design of organelle-targeted chemical agents. These opportunities include (1) development of quantitative, non-fluorescence-based, whole cell methods and techniques to measure the subcellular distribution of chemical agents in multiple compartments; (2) exploratory experimentation with nonspecific transport probes that have not been enriched with putative, organelle-targeting features; (3) elaboration of hypothesis-driven, mechanistic and modeling-based approaches to guide experiments aimed at elucidating subcellular distribution and transport; and (4) introduction of revolutionary conceptual approaches borrowed from the field of synthetic biology combined with cutting edge experimental strategies. In our laboratory, state-of-the-art subcellular transport studies are now being aimed at understanding the formation of new intracellular membrane structures in response to drug therapy, exploring the function of drug-membrane complexes as intracellular drug depots, and synthesizing new organelles with extraordinary physical and chemical properties.
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Affiliation(s)
- Nan Zheng
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Michigan, Ann Arbor, Michigan 48109, United States
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18
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Cochemé HM, Murphy MP. Chapter 22 The Uptake and Interactions of the Redox Cycler Paraquat with Mitochondria. Methods Enzymol 2009; 456:395-417. [DOI: 10.1016/s0076-6879(08)04422-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
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20
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Abstract
A general protocol is described to improve the specificity for imaging superoxide formation in live cells via fluorescence microscopy with either hydroethidine (HE) or its mitochondrially targeted derivative Mito-HE (MitoSOX Red). Two different excitation wavelengths are used to distinguish the superoxide-dependent hydroxylation of Mito-HE (385-405 nm) from the nonspecific formation of ethidium (480-520 nm). Furthermore, the dual wavelength imaging in live cells can be combined with immunocolocalization, which allows superoxide formation to be compared simultaneously in cocultures of two types of genetically manipulated cells in the same microscopic field. The combination of these approaches can greatly improve the specificity for imaging superoxide formation in cultured cells and tissues.
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Cochemé HM, Murphy MP. Complex I Is the Major Site of Mitochondrial Superoxide Production by Paraquat. J Biol Chem 2008; 283:1786-98. [DOI: 10.1074/jbc.m708597200] [Citation(s) in RCA: 415] [Impact Index Per Article: 25.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
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22
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Shaw CA, Höglinger GU. Neurodegenerative diseases: neurotoxins as sufficient etiologic agents? Neuromolecular Med 2007; 10:1-9. [PMID: 17985252 DOI: 10.1007/s12017-007-8016-8] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2007] [Accepted: 10/09/2007] [Indexed: 11/26/2022]
Abstract
A dominant paradigm in neurological disease research is that the primary etiological factors for diseases such as Alzheimer's (AD), Parkinson's (PD), and amyotrophic lateral sclerosis (ALS) are genetic. Opposed to this perspective are the clear observations from epidemiology that purely genetic casual factors account for a relatively small fraction of all cases. Many who support a genetic etiology for neurological disease take the view that while the percentages may be relatively small, these numbers will rise in the future with the inevitable discoveries of additional genetic mutations. The follow up argument is that even if the last is not true, the events triggered by the aberrant genes identified so far will be shown to impact the same neuronal cell death pathways as those activated by environmental factors that trigger most sporadic disease cases. In this article we present a countervailing view that environmental neurotoxins may be the sole sufficient factor in at least three neurological disease clusters. For each, neurotoxins have been isolated and characterized that, at least in animal models, faithfully reproduce each disorder without the need for genetic co-factors. Based on these data, we will propose a set of principles that would enable any potential toxin to be evaluated as an etiological factor in a given neurodegenerative disease. Finally, we will attempt to put environmental toxins into the context of possible genetically-determined susceptibility.
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Affiliation(s)
- Christopher A Shaw
- Department of Ophthalmology, University of British Columbia, Vancouver, BC, Canada.
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James AM, Sharpley MS, Manas ARB, Frerman FE, Hirst J, Smith RAJ, Murphy MP. Interaction of the Mitochondria-targeted Antioxidant MitoQ with Phospholipid Bilayers and Ubiquinone Oxidoreductases. J Biol Chem 2007; 282:14708-18. [PMID: 17369262 DOI: 10.1074/jbc.m611463200] [Citation(s) in RCA: 191] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
MitoQ(10) is a ubiquinone that accumulates within mitochondria driven by a conjugated lipophilic triphenylphosphonium cation (TPP(+)). Once there, MitoQ(10) is reduced to its active ubiquinol form, which has been used to prevent mitochondrial oxidative damage and to infer the involvement of reactive oxygen species in signaling pathways. Here we show MitoQ(10) is effectively reduced by complex II, but is a poor substrate for complex I, complex III, and electron-transferring flavoprotein (ETF):quinone oxidoreductase (ETF-QOR). This differential reactivity could be explained if the bulky TPP(+) moiety sterically hindered access of the ubiquinone group to enzyme active sites with a long, narrow access channel. Using a combination of molecular modeling and an uncharged analog of MitoQ(10) with similar sterics (tritylQ(10)), we infer that the interaction of MitoQ(10) with complex I and ETF-QOR, but not complex III, is inhibited by its bulky TPP(+) moiety. To explain its lack of reactivity with complex III we show that the TPP(+) moiety of MitoQ(10) is ineffective at quenching pyrene fluorophors deeply buried within phospholipid bilayers and thus is positioned near the membrane surface. This superficial position of the TPP(+) moiety, as well as the low solubility of MitoQ(10) in non-polar organic solvents, suggests that the concentration of the entire MitoQ(10) molecule in the membrane core is very limited. As overlaying MitoQ(10) onto the structure of complex III indicates that MitoQ(10) cannot react with complex III without its TPP(+) moiety entering the low dielectric of the membrane core, we conclude that the TPP(+) moiety does anchor the tethered ubiquinol group out of reach of the active site(s) of complex III, thus explaining its slow oxidation. In contrast the ubiquinone moiety of MitoQ(10) is able to quench fluorophors deep within the membrane core, indicating a high concentration of the ubiquinone moiety within the membrane and explaining its good anti-oxidant efficacy. These findings will facilitate the rational design of future mitochondria-targeted molecules.
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Affiliation(s)
- Andrew M James
- Medical Research Council Dunn Human Nutrition Unit, Wellcome Trust/MRC Building, Hills Road, Cambridge CB2 2XY, United Kingdom
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24
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Neuzil J, Dong LF, Ramanathapuram L, Hahn T, Chladova M, Wang XF, Zobalova R, Prochazka L, Gold M, Freeman R, Turanek J, Akporiaye ET, Dyason JC, Ralph SJ. Vitamin E analogues as a novel group of mitocans: anti-cancer agents that act by targeting mitochondria. Mol Aspects Med 2007; 28:607-45. [PMID: 17499351 DOI: 10.1016/j.mam.2007.02.003] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2007] [Revised: 02/12/2007] [Accepted: 02/13/2007] [Indexed: 12/12/2022]
Abstract
Mitochondria have recently emerged as new and promising targets for cancer prevention and therapy. One of the reasons for this is that mitochondria are instrumental to many types of cell death and often lie downstream from the initial actions of anti-cancer drugs. Unlike the tumour suppressor gene encoding p53 that is notoriously prone to inactivating mutations but whose function is essential for induction of apoptosis by DNA-targeting agents (such as doxorubicin or 5-fluorouracil), mitochondria present targets that are not so compromised by genetic mutation and whose targeting overcomes problems with mutations of upstream targets such as p53. We have recently proposed a novel class of anti-cancer agents, mitocans that exert their anti-cancer activity by destabilising mitochondria, promoting the selective induction of apoptotic death in tumour cells. In this communication, we review recent findings on mitocans and propose a common basis for their mode of action in inducing apoptosis of cancer cells. We use as an example the analogues of vitamin E that are proving to be cancer cell-specific and may soon be developed into efficient anti-cancer drugs.
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Affiliation(s)
- Jiri Neuzil
- Apoptosis Research Group, School of Medical Science, Griffith University, Southport, Qld, Australia.
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25
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Ross M, Da Ros T, Blaikie F, Prime T, Porteous C, Severina I, Skulachev V, Kjaergaard H, Smith R, Murphy M. Accumulation of lipophilic dications by mitochondria and cells. Biochem J 2006; 400:199-208. [PMID: 16948637 PMCID: PMC1635440 DOI: 10.1042/bj20060919] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Lipophilic monocations can pass through phospholipid bilayers and accumulate in negatively-charged compartments such as the mitochondrial matrix, driven by the membrane potential. This property is used to visualize mitochondria, to deliver therapeutic molecules to mitochondria and to measure the membrane potential. In theory, lipophilic dications have a number of advantages over monocations for these tasks, as the double charge should lead to a far greater and more selective uptake by mitochondria, increasing their therapeutic potential. However, the double charge might also limit the movement of lipophilic dications through phospholipid bilayers and little is known about their interaction with mitochondria. To see whether lipophilic dications could be taken up by mitochondria and cells, we made a series of bistriphenylphosphonium cations comprising two triphenylphosphonium moieties linked by a 2-, 4-, 5-, 6- or 10-carbon methylene bridge. The 5-, 6- and 10-carbon dications were taken up by energized mitochondria, whereas the 2- and 4-carbon dications were not. The accumulation of the dication was greater than that of the monocation methyltriphenylphosphonium. However, the uptake of dications was only described by the Nernst equation at low levels of accumulation, and beyond a threshold membrane potential of 90-100 mV there was negligible increase in dication uptake. Interestingly, the 5- and 6-carbon dications were not accumulated by cells, due to lack of permeation through the plasma membrane. These findings indicate that conjugating compounds to dications offers only a minor increase over monocations in delivery to mitochondria. Instead, this suggests that it may be possible to form dications within mitochondria that then remain within the cell.
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Affiliation(s)
- Meredith F. Ross
- *Medical Research Council Dunn Human Nutrition Unit, Wellcome Trust/MRC Building, Hills Road, Cambridge CB2 2XY, U.K
| | - Tatiana Da Ros
- †Pharmaceutical Science Department, Trieste University, 34127 Trieste, Italy
| | - Frances H. Blaikie
- ‡Department of Chemistry, University of Otago, Box 56, Dunedin, New Zealand
| | - Tracy A. Prime
- *Medical Research Council Dunn Human Nutrition Unit, Wellcome Trust/MRC Building, Hills Road, Cambridge CB2 2XY, U.K
| | - Carolyn M. Porteous
- §Department of Biochemistry, University of Otago, Box 56, Dunedin, New Zealand
| | - Inna I. Severina
- ∥A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow 119992, Russia
| | - Vladimir P. Skulachev
- ∥A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow 119992, Russia
| | | | - Robin A. J. Smith
- ‡Department of Chemistry, University of Otago, Box 56, Dunedin, New Zealand
| | - Michael P. Murphy
- *Medical Research Council Dunn Human Nutrition Unit, Wellcome Trust/MRC Building, Hills Road, Cambridge CB2 2XY, U.K
- To whom correspondence should be addressed (email )
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Robinson KM, Janes MS, Pehar M, Monette JS, Ross MF, Hagen TM, Murphy MP, Beckman JS. Selective fluorescent imaging of superoxide in vivo using ethidium-based probes. Proc Natl Acad Sci U S A 2006; 103:15038-43. [PMID: 17015830 PMCID: PMC1586181 DOI: 10.1073/pnas.0601945103] [Citation(s) in RCA: 619] [Impact Index Per Article: 34.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The putative oxidation of hydroethidine (HE) has become a widely used fluorescent assay for the detection of superoxide in cultured cells. By covalently joining HE to a hexyl triphenylphosphonium cation (Mito-HE), the HE moiety can be targeted to mitochondria. However, the specificity of HE and Mito-HE for superoxide in vivo is limited by autooxidation as well as by nonsuperoxide-dependent cellular processes that can oxidize HE probes to ethidium (Etd). Recently, superoxide was shown to react with HE to generate 2-hydroxyethidium [Zhao, H., Kalivendi, S., Zhang, H., Joseph, J., Nithipatikom, K., Vasquez-Vivar, J. & Kalyanaraman, B. (2003) Free Radic. Biol. Med. 34, 1359-1368]. However, 2-hydroxyethidium is difficult to distinguish from Etd by conventional fluorescence techniques exciting at 510 nm. While investigating the oxidation of Mito-HE by superoxide, we found that the superoxide product of both HE and Mito-HE could be selectively excited at 396 nm with minimal interference from other nonspecific oxidation products. The oxidation of Mito-HE monitored at 396 nm by antimycin-stimulated mitochondria was 30% slower than at 510 nm, indicating that superoxide production may be overestimated at 510 nm by even a traditional superoxide-stimulating mitochondrial inhibitor. The rate-limiting step for oxidation by superoxide was 4x10(6) M-1.s-1, which is proposed to involve the formation of a radical from Mito-HE. The rapid reaction with a second superoxide anion through radical-radical coupling may explain how Mito-HE and HE can compete for superoxide in vivo with intracellular superoxide dismutases. Monitoring oxidation at both 396 and 510 nm of excitation wavelengths can facilitate the more selective detection of superoxide in vivo.
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Affiliation(s)
- Kristine M. Robinson
- *Linus Pauling Institute, Department of Biochemistry and Biophysics, Oregon State University, Corvallis, OR 97331
| | - Michael S. Janes
- *Linus Pauling Institute, Department of Biochemistry and Biophysics, Oregon State University, Corvallis, OR 97331
- Invitrogen–Molecular Probes Labeling and Detection Technologies, Eugene, OR 97402
| | - Mariana Pehar
- Departamento de Neurobiología Celular, Instituto de Investigaciones Biológicas Clemente Estable, Av. Italia 3318, 11600 Montevideo, Uruguay
| | - Jeffrey S. Monette
- *Linus Pauling Institute, Department of Biochemistry and Biophysics, Oregon State University, Corvallis, OR 97331
| | - Meredith F. Ross
- Medical Research Council, Dunn Human Nutrition Unit, Hills Road, Cambridge CB2 2XY, United Kingdom; and
| | - Tory M. Hagen
- *Linus Pauling Institute, Department of Biochemistry and Biophysics, Oregon State University, Corvallis, OR 97331
| | - Michael P. Murphy
- Medical Research Council, Dunn Human Nutrition Unit, Hills Road, Cambridge CB2 2XY, United Kingdom; and
| | - Joseph S. Beckman
- *Linus Pauling Institute, Department of Biochemistry and Biophysics, Oregon State University, Corvallis, OR 97331
- To whom correspondence should be addressed. E-mail:
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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: 53] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [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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Abstract
1-Methy-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) is a potent neurotoxin extensively used to model Parkinson's disease (PD). A cascade of deleterous events, in which mitochondria play a pivotal role, drives MPTP neurotoxicity. How mitochondria are affected by MPTP and how their defect contributes to the demise of dopaminergic neurons in this model of PD are discussed in this review.
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Affiliation(s)
- Serge Przedborski
- Department of Neurology, Columbia University, New York, New York 10032, USA.
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Filipovska A, Kelso GF, Brown SE, Beer SM, Smith RAJ, Murphy MP. Synthesis and characterization of a triphenylphosphonium-conjugated peroxidase mimetic. Insights into the interaction of ebselen with mitochondria. J Biol Chem 2005; 280:24113-26. [PMID: 15831495 DOI: 10.1074/jbc.m501148200] [Citation(s) in RCA: 105] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Mitochondrial production of peroxides is a critical event in both pathology and redox signaling. Consequently their selective degradation within mitochondria is of considerable interest. Here we have explored the interaction of the peroxidase mimetic ebselen with mitochondria. We were particularly interested in whether ebselen was activated by mitochondrial glutathione (GSH) and thioredoxin, in determining whether an ebselen moiety could be targeted to mitochondria by conjugating it to a lipophilic cation, and in exploring the nature of ebselen binding to mitochondrial proteins. To achieve these goals we synthesized 2-[4-(4-triphenylphosphoniobutoxy) phenyl]-1,2-benzisoselenazol)-3(2H)-one iodide (MitoPeroxidase), which contains an ebselen moiety covalently linked to a triphenylphosphonium (TPP) cation. The fixed positive charge of TPP facilitated mass spectrometric analysis, which showed that the ebselen moiety was reduced by GSH to the selenol form and that subsequent reaction with a peroxide reformed the ebselen moiety. MitoPeroxidase and ebselen were effective antioxidants that degraded phospholipid hydroperoxides, prevented lipid peroxidation, and protected mitochondria from oxidative damage. Both peroxidase mimetics required activation by mitochondrial GSH or thioredoxin to be effective antioxidants. Surprisingly, conjugation to the TPP cation led to only a slight increase in the uptake of ebselen by mitochondria due to covalent binding of the ebselen moiety to proteins. Using antiserum against the TPP moiety we visualized those proteins covalently attached to the ebselen moiety. This analysis indicated that much of the ebselen present within mitochondria is bound to protein thiols through reversible selenenylsulfide bonds. Both MitoPeroxidase and ebselen decreased apoptosis induced by oxidative stress, suggesting that they can decrease mitochondrial oxidative stress. This exploration has led to new insights into the behavior of peroxidase mimetics within mitochondria and to their use in investigating mitochondrial oxidative damage.
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Affiliation(s)
- Aleksandra Filipovska
- Medical Research Council Dunn Human Nutrition Unit, Wellcome Trust/MRC Bldg., Hills Rd., Cambridge CB2 2XY, United Kingdom
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Loots DT, Mienie LJ, Bergh JJ, Van der Schyf CJ. Acetyl-L-carnitine prevents total body hydroxyl free radical and uric acid production induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) in the rat. Life Sci 2004; 75:1243-53. [PMID: 15219812 DOI: 10.1016/j.lfs.2004.03.007] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2003] [Accepted: 03/11/2004] [Indexed: 12/17/2022]
Abstract
Acetyl-L-carnitine (ALCAR) is intimately involved in the transport of long chain fatty acids across the inner mitochondrial membrane during oxidative phosphorylation. ALCAR also has been reported to attenuate the occurrence of parkinsonian symptoms associated with 1-methyl-1,2,3,6-tetrahydropyridine (MPTP) in vivo, and protects in vitro against the toxicity of the neurotoxic 1-methyl-4-phenylpyridinium (MPP+) metabolite of MPTP. The mechanism for these protective effects remains unclear. ALCAR may attenuate hydroxyl (HO*) free radical production in the MPTP/MPP+ neurotoxic pathway through several mechanisms. Most studies on MPTP/MPP+ toxicity and protection by ALCAR have focused on in vivo brain chemistry and in vitro neuronal culture studies. The present study investigates the attenuative effects of ALCAR on whole body oxidative stress markers in the urine of rats treated with MPTP. In a first study, ALCAR totally prevented the MPTP-induced formation of HO* measured by salicylate radical trapping. In a second study, the production of uric acid after MPTP administration-a measure of oxidative stress mediated through xanthine oxidase-was also prevented by ALCAR. Because ALCAR is unlikely to be a potent radical scavenger, these studies suggest that ALCAR protects against MPTP/MPP+-mediated oxidative stress through other mechanisms. We speculate that ALCAR may operate through interference with organic cation transporters such as OCTN2 and/or carnitine-acylcarnitine translocase (CACT), based partly on the above findings and on semi-empirical electronic similarity calculations on ALCAR, MPP+, and two other substrates for these transporters.
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Affiliation(s)
- Du Toit Loots
- Department of Biochemistry, North West University, Potchefstroom 2520, South Africa
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Asin-Cayuela J, Manas ARB, James AM, Smith RAJ, Murphy MP. Fine-tuning the hydrophobicity of a mitochondria-targeted antioxidant. FEBS Lett 2004; 571:9-16. [PMID: 15280009 DOI: 10.1016/j.febslet.2004.06.045] [Citation(s) in RCA: 148] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2004] [Revised: 06/13/2004] [Accepted: 06/23/2004] [Indexed: 12/22/2022]
Abstract
The mitochondria-targeted antioxidant MitoQ comprises a ubiquinol moiety covalently attached through an aliphatic carbon chain to the lipophilic triphenylphosphonium cation. This cation drives the membrane potential-dependent accumulation of MitoQ into mitochondria, enabling the ubiquinol antioxidant to prevent mitochondrial oxidative damage far more effectively than untargeted antioxidants. We sought to fine-tune the hydrophobicity of MitoQ so as to control the extent of its membrane binding and penetration into the phospholipid bilayer, and thereby regulate its partitioning between the membrane and aqueous phases within mitochondria and cells. To do this, MitoQ variants with 3, 5, 10 and 15 carbon aliphatic chains were synthesised. These molecules had a wide range of hydrophobicities with octan-1-ol/phosphate buffered saline partition coefficients from 2.8 to 20000. All MitoQ variants were accumulated into mitochondria driven by the membrane potential, but their binding to phospholipid bilayers varied from negligible for MitoQ3 to essentially total for MitoQ15. Despite the span of hydrophobicites, all MitoQ variants were effective antioxidants. Therefore, it is possible to fine-tune the degree of membrane association of MitoQ and other mitochondria targeted compounds, without losing antioxidant efficacy. This indicates how the uptake and distribution of mitochondria-targeted compounds within mitochondria and cells can be controlled, thereby facilitating investigations of mitochondrial oxidative damage.
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Affiliation(s)
- Jordi Asin-Cayuela
- Medical Research Council Dunn Human Nutrition Unit, Wellcome Trust/MRC Building, Hills Road, Cambridge CB2 2XY, UK
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32
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Affiliation(s)
- Robin A J Smith
- Department of Chemistry, University of Otago, Dunedin, New Zealand
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33
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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: 241] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [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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34
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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. EUROPEAN JOURNAL OF BIOCHEMISTRY 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] [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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Taylor ER, Hurrell F, Shannon RJ, Lin TK, Hirst J, Murphy MP. Reversible glutathionylation of complex I increases mitochondrial superoxide formation. J Biol Chem 2003; 278:19603-10. [PMID: 12649289 DOI: 10.1074/jbc.m209359200] [Citation(s) in RCA: 314] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Increased production of reactive oxygen species (ROS) by mitochondria is involved in oxidative damage to the organelle and in committing cells to apoptosis or senescence, but the mechanisms of this increase are unknown. Here we show that ROS production by mitochondrial complex I increases in response to oxidation of the mitochondrial glutathione pool. This correlates with thiols on the 51- and 75-kDa subunits of complex I forming mixed disulfides with glutathione. Glutathionylation of complex I increases superoxide production by the complex, and when the mixed disulfides are reduced, superoxide production returns to basal levels. Within intact mitochondria oxidation of the glutathione pool to glutathione disulfide also leads to glutathionylation of complex I, which correlates with increased superoxide formation. In this case, most of this superoxide is converted to hydrogen peroxide, which can then diffuse into the cytoplasm. This mechanism of reversible mitochondrial ROS production suggests how mitochondria might regulate redox signaling and shows how oxidation of the mitochondrial glutathione pool could contribute to the pathological changes that occur to mitochondria during oxidative stress.
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Affiliation(s)
- Ellen R Taylor
- Medical Research Council-Dunn Human Nutrition Unit, Wellcome Trust-MRC Bldg., Hills Rd., Cambridge CB2 2XY, United Kingdom
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Stephans SE, Miller GW, Levey AI, Greenamyre JT. Acute mitochondrial and chronic toxicological effects of 1-methyl-4-phenylpyridinium in human neuroblastoma cells. Neurotoxicology 2002; 23:569-80. [PMID: 12428729 DOI: 10.1016/s0161-813x(02)00060-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
At low micromolar concentrations, 1-methyl-4-phenylpyridinium (MPP+), the toxic metabolite of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) selectively kills nigrostriatal dopaminergic neurons by mechanisms believed to involve impairment of mitochondrial complex I. A human neuroblastoma cell line expressing the dopamine transporter (DAT) was utilized to examine the effects of MPP+ on acute physiologic responses and subsequent cell death. Acute responses were measured by microphysiometry and by monitoring mitochondrial membrane potential with [3H]tetraphenylphosphonium (TPP+) uptake. MPP+ (10 microM) increased extracellular proton excretion in DAT-expressing cells within 2-3 min, but had no effect in untransfected cells. The lipophilic complex I inhibitor, rotenone, increased proton excretion in both cell lines. In DAT-expressing cells, mitochondrial membrane potential was reduced within I h of 10 microM MPP+ exposure. Rotenone reduced mitochondrial membrane potential in both cell lines. MPP+ caused apoptotic death of DAT-transfected cells 2-3 days after drug application, but did not kill untransfected cells. Thus, MPP+ produces immediate mitochondrial impairment only in cells that express DAT, and these changes occur days before overt cellular toxicity. The magnitude, time course and nature of these changes were similar to those produced by rotenone, confirming the site of action of MPP+ as mitochondrial complex I. These immediate mitochondrial effects appear to be an accurate predictor of subsequent cell death.
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Affiliation(s)
- Stacy E Stephans
- Department of Neurology, Center for Neurodegenerative Diseases, School of Medicine, Emory University, Atlanta, GA 30322, USA
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Muratovska A, Lightowlers RN, Taylor RW, Turnbull DM, Smith RA, Wilce JA, Martin SW, Murphy MP. Targeting peptide nucleic acid (PNA) oligomers to mitochondria within cells by conjugation to lipophilic cations: implications for mitochondrial DNA replication, expression and disease. Nucleic Acids Res 2001; 29:1852-63. [PMID: 11328868 PMCID: PMC37250 DOI: 10.1093/nar/29.9.1852] [Citation(s) in RCA: 120] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The selective manipulation of mitochondrial DNA (mtDNA) replication and expression within mammalian cells has proven difficult. One promising approach is to use peptide nucleic acid (PNA) oligomers, nucleic acid analogues that bind selectively to complementary DNA or RNA sequences inhibiting replication and translation. However, the potential of PNAs is restricted by the difficulties of delivering them to mitochondria within cells. To overcome this problem we conjugated a PNA 11mer to a lipophilic phosphonium cation. Such cations are taken up by mitochondria through the lipid bilayer driven by the membrane potential across the inner membrane. As anticipated, phosphonium-PNA (ph-PNA) conjugates of 3.4-4 kDa were imported into both isolated mitochondria and mitochondria within human cells in culture. This was confirmed by using an ion-selective electrode to measure uptake of the ph-PNA conjugates; by cell fractionation in conjunction with immunoblotting; by confocal microscopy; by immunogold-electron microscopy; and by crosslinking ph-PNA conjugates to mitochondrial matrix proteins. In all cases dissipating the mitochondrial membrane potential with an uncoupler prevented ph-PNA uptake. The ph-PNA conjugate selectively inhibited the in vitro replication of DNA containing the A8344G point mutation that causes the human mtDNA disease 'myoclonic epilepsy and ragged red fibres' (MERRF) but not the wild-type sequence that differs at a single nucleotide position. Therefore these modified PNA oligomers retain their selective binding to DNA and the lipophilic cation delivers them to mitochondria within cells. When MERRF cells were incubated with the ph-PNA conjugate the ratio of MERRF to wild-type mtDNA was unaffected, even though the ph-PNA content of the mitochondria was sufficient to inhibit MERRF mtDNA replication in a cell-free system. This unexpected finding suggests that nucleic acid derivatives cannot bind their complementary sequences during mtDNA replication. In summary, we have developed a new strategy for targeting PNA oligomers to mitochondria and used it to determine the effects of PNA on mutated mtDNA replication in cells. This work presents new approaches for the manipulation of mtDNA replication and expression, and will assist in the development of therapies for mtDNA diseases.
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Affiliation(s)
- A Muratovska
- Department of Biochemistry, University of Otago, PO Box 56, Dunedin, New Zealand
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Abstract
The major function of mitochondria in human cells is to provide ATP by oxidative phosphorylation. However, mitochondria have many other roles including the modulation of intracellular calcium concentration and the regulation of apoptotic cell death. Furthermore, the mitochondrial respiratory chain is a major source of damaging free radicals. Consequently, mitochondrial dysfunction contributes to a number of human diseases, ranging from neurodegenerative diseases and ischaemia-reperfusion injury to obesity and diabetes. In addition, mutations to nuclear or mitochondrial DNA cause a number of human diseases. Therefore, strategies to prevent mitochondrial damage or to manipulate mitochondrial function in clinically useful ways may provide new therapies for a range of human disorders. Here we outline why mitochondria are a potentially important target for drug delivery and discuss how to deliver bioactive molecules selectively to mitochondria within cells.
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Affiliation(s)
- M P Murphy
- Department of Biochemistry, University of Otago, Box 56, Dunedin, New Zealand.
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Abstract
Mitochondria play a central role in the survival and death of neurons. The detailed bioenergetic mechanisms by which isolated mitochondria generate ATP, sequester Ca(2+), generate reactive oxygen species, and undergo Ca(2+)-dependent permeabilization of their inner membrane are currently being applied to the function of mitochondria in situ within neurons under physiological and pathophysiological conditions. Here we review the functional bioenergetics of isolated mitochondria, with emphasis on the chemiosmotic proton circuit and the application (and occasional misapplication) of these principles to intact neurons. Mitochondria play an integral role in both necrotic and apoptotic neuronal cell death, and the bioenergetic principles underlying current studies are reviewed.
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Affiliation(s)
- D G Nicholls
- Department of Pharmacology, University of Dundee, Dundee, Scotland.
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Singer TP, Ramsay RR, Ackrell BA. Deficiencies of NADH and succinate dehydrogenases in degenerative diseases and myopathies. BIOCHIMICA ET BIOPHYSICA ACTA 1995; 1271:211-9. [PMID: 7599211 DOI: 10.1016/0925-4439(95)00030-8] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
This paper examines the experimental foundations of reports in the literature on mitochondrial diseases involving Complexes I and II of the respiratory chain. Many of the reports may be questioned on the basis of the assay conditions used which disregard established knowledge of the precautions required for valid activity measurements. In addition, some findings are open to question because of the experimental material chosen for the study, such as the measurement of NADH oxidase activity in platelets in Parkinson's disease, which affects selectively the dopamine neurons, or the use of autopsy material stored for prolonged periods during which post-mortem changes may have occurred. Deficiencies claimed to involve several components of the respiratory chain may reflect indirect effects, such as defects in the synthesis of iron-sulfur clusters or in the availability of iron, rather than mutations in the genes coding for the deficient enzymes. Nevertheless, there are a few instances reported of Complex II deficiency free from such criticisms. As to Complex I, idiopathic Parkinsonism appears to involve a documentable decline in the activity of this enzyme. Using the model system provided by N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), which produces biochemical, pharmacological, and clinical syndromes closely resembling Parkinsonism, the etiology of the disease is examined.
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Affiliation(s)
- T P Singer
- Department of Biochemistry and Biophysics, University of California, San Francisco, USA
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41
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Murphy MP, Krueger MJ, Sablin SO, Ramsay RR, Singer TP. Inhibition of complex I by hydrophobic analogues of N-methyl-4-phenylpyridinium (MPP+) and the use of an ion-selective electrode to measure their accumulation by mitochondria and electron-transport particles. Biochem J 1995; 306 ( Pt 2):359-65. [PMID: 7887889 PMCID: PMC1136529 DOI: 10.1042/bj3060359] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
N-methyl-4-phenylpyridinium (MPP+), the neurotoxic metabolite of N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, kills dopaminergic neurons after its accumulation in mitochondria where it inhibits Complex I of the respiratory chain. MPP+ inhibits respiration by binding to both a hydrophobic and a hydrophilic site on Complex I and this inhibition is increased by the lipophilic tetraphenylboron anion (TPB-) which facilitates movement of MPP+ through membranes and its penetration to the hydrophobic binding site on Complex I. To investigate the inhibition of respiration by MPP(+)-like compounds, we have measured simultaneously NADH-linked mitochondrial respiration and the uptake and accumulation of the N-benzyl-4-styrylpyridinium and N-ethyl-4-styrylpyridinium cations in mitochondria using ion-selective electrodes. The data provide direct evidence that TPB- increases the inhibition not by increasing matrix concentration but by facilitating access to the inhibitory sites on Complex I. We have also compared the rates of uptake of MPP+ analogues of varied lipophilicity by the inner membrane and the development of inhibition of NADH oxidation, using an inverted mitochondrial inner membrane preparation and appropriate ion-selective electrodes. These experiments demonstrated that the amount of MPP+ analogue bound to the inner membrane greatly exceeded the quantity required for complete inhibition of NADH oxidation. Moreover, binding to the membrane occurred much more rapidly than the development of inhibition with all MPP+ analogues tested. This suggests that the attainment of a correct orientation of these compounds within the membrane and the binding site may be a rate-limiting step in the development of inhibition.
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Affiliation(s)
- M P Murphy
- Department of Biochemistry, University of Otago, Dunedin, New Zealand
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42
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Singer TP, Ramsay RR. The reaction sites of rotenone and ubiquinone with mitochondrial NADH dehydrogenase. BIOCHIMICA ET BIOPHYSICA ACTA 1994; 1187:198-202. [PMID: 8075112 DOI: 10.1016/0005-2728(94)90110-4] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
This article summarizes recent studies in the authors' and other laboratories of selective inhibitors acting at the 'rotenone' site and at the Q binding site in the NADH-Q oxidoreductase segment of the respiratory chain. A wide array of inhibitors act at the rotenone site to block electron flux from the enzyme to the Q pool. Using evidence from studies with rotenone, piericidin A, and analogs of the neurotoxic N-methyl-4-phenylpyridinium, we have proposed two binding sites for these inhibitors, both of which must be occupied for complete inhibition of NADH oxidation.
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Affiliation(s)
- T P Singer
- Department of Biochemistry and Biophysics, University of California, San Francisco
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Tipton KF, Singer TP. Advances in our understanding of the mechanisms of the neurotoxicity of MPTP and related compounds. J Neurochem 1993; 61:1191-206. [PMID: 8376979 DOI: 10.1111/j.1471-4159.1993.tb13610.x] [Citation(s) in RCA: 401] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- K F Tipton
- Department of Biochemistry, Trinity College, Dublin, Ireland
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