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Dong F, Lojko P, Bazzone A, Bernhard F, Borodina I. Transporter function characterization via continuous-exchange cell-free synthesis and solid supported membrane-based electrophysiology. Bioelectrochemistry 2024; 159:108732. [PMID: 38810322 DOI: 10.1016/j.bioelechem.2024.108732] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2024] [Revised: 05/02/2024] [Accepted: 05/13/2024] [Indexed: 05/31/2024]
Abstract
Functional characterization of transporters is impeded by the high cost and technical challenges of current transporter assays. Thus, in this work, we developed a new characterization workflow that combines cell-free protein synthesis (CFPS) and solid supported membrane-based electrophysiology (SSME). For this, membrane protein synthesis was accomplished in a continuous exchange cell-free system (CECF) in the presence of nanodiscs. The resulting transporters expressed in nanodiscs were incorporated into proteoliposomes and assayed in the presence of different substrates using the surface electrogenic event reader. As a proof of concept, we validated this workflow to express and characterize five diverse transporters: the drug/H+-coupled antiporters EmrE and SugE, the lactose permease LacY, the Na+/H+ antiporter NhaA from Escherichia coli, and the mitochondrial carrier AAC2 from Saccharomyces cerevisiae. For all transporters kinetic parameters, such as KM, IMAX, and pH dependency, were evaluated. This robust and expedite workflow (e.g., can be executed within only five workdays) offers a convenient direct functional assessment of transporter protein activity and has the ability to facilitate applications of transporters in medical and biotechnological research.
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Affiliation(s)
- Fang Dong
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Denmark
| | - Pawel Lojko
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Denmark
| | | | - Frank Bernhard
- Institute of Biophysical Chemistry, Centre for Biomolecular Magnetic Resonance, J.W. Goethe-University, Frankfurt am Main, Germany
| | - Irina Borodina
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Denmark.
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2
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Pommereau A, Licher T, Bärenz F. Solid-Supported Membrane (SSM)-Based Electrophysiology Assays Using Surface Electrogenic Event Reader Technology (SURFE²R) in Early Drug Discovery. Curr Protoc 2023; 3:e650. [PMID: 36912603 DOI: 10.1002/cpz1.650] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/14/2023]
Abstract
This article presents detailed descriptions of procedures and troubleshooting tips for solid-supported membrane (SSM)-based electrophysiology assays (SURFE²R) to measure electrogenic solute carrier transporter proteins (SLCs) and assess the effects of compounds that modulate their activity. SURFE²R allows the use of the standard 96-well format, making it an ideal platform for tertiary assays in a drug-discovery campaign. The assays are performed with cell-line-derived membrane fractions or proteoliposomes containing the transporter of interest. Three main protocols are described for the isolation of membrane fractions from cell culture and the generation of proteoliposomes containing the transporter of interest. Additionally, detailed protocols for SURFE²R single concentration and dose-response experiments are included to measure the potencies of test compounds in stimulating or inhibiting transporter function (EC50 or IC50 values, respectively) and kinetic functional assays to calculate apparent affinity (kM ) and maximal velocity (Vmax ) of substrate uptake. © 2023 Sanofi. Current Protocols published by Wiley Periodicals LLC. PROTOCOL GROUP 1: Sample preparation for SSM-based electrophysiology assays Support Protocol 1: Production of cell batches Support Protocol 2: Simple isolation of cell membranes Alternate Protocol 1: Isolation of cell membranes with sucrose gradient pre-purification Support Protocol 3: Production and isolation of liposomes Support Protocol 4: Preparation of sensor with isolated cell membranes Alternate Protocol 2: Preparation of sensor with isolated proteoliposomes PROTOCOL GROUP 2: Determination of assay parameters for SSM-based electrophysiology assay Support Protocol 5: Assay with stable buffer Alternate Protocol 3: Assay with ion gradient Support Protocol 6: Determination of membrane/liposome concentration Support Protocol 7: Determination of substrate dependency kM PROTOCOL GROUP 3: Determination of advanced assay parameters for SSM-based electrophysiology assays Support Protocol 8: Assessment of ion concentration dependency Support Protocol 9: Assessment of pH dependency Support Protocol 10: Assessment of DMSO dependency Support Protocol 11: Assessment of signal stability with multiple activations PROTOCOL GROUP 4: Compound testing through SSM-based electrophysiology assays using SURFE²R apparatus Support Protocol 12: Assessment of signal specificity of a published inhibitor or unknown compound(s) Support Protocol 13: Compound wash-out Support Protocol 14: Statistical analysis.
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Affiliation(s)
- Antje Pommereau
- Sanofi, Integrated Drug Discovery, Industriepark Hoechst, Frankfurt am Main, Germany
| | - Thomas Licher
- Sanofi, Integrated Drug Discovery, Industriepark Hoechst, Frankfurt am Main, Germany
| | - Felix Bärenz
- Sanofi, Integrated Drug Discovery, Industriepark Hoechst, Frankfurt am Main, Germany
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3
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Wei M, Ye Y, Ali MM, Chamba Y, Tang J, Shang P. Effect of Fluoride on Cytotoxicity Involved in Mitochondrial Dysfunction: A Review of Mechanism. Front Vet Sci 2022; 9:850771. [PMID: 35518640 PMCID: PMC9062983 DOI: 10.3389/fvets.2022.850771] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2022] [Accepted: 02/07/2022] [Indexed: 12/11/2022] Open
Abstract
Fluoride is commonly found in the soil and water environment and may act as chronic poison. A large amount of fluoride deposition causes serious harm to the ecological environment and human health. Mitochondrial dysfunction is a shared feature of fluorosis, and numerous studies reported this phenomenon in different model systems. More and more evidence shows that the functions of mitochondria play an extremely influential role in the organs and tissues after fluorosis. Fluoride invades into cells and mainly damages mitochondria, resulting in decreased activity of mitochondrial related enzymes, weakening of protein expression, damage of respiratory chain, excessive fission, disturbance of fusion, disorder of calcium regulation, resulting in the decrease of intracellular ATP and the accumulation of Reactive oxygen species. At the same time, the decrease of mitochondrial membrane potential leads to the release of Cyt c, causing a series of caspase cascade reactions and resulting in apoptosis. This article mainly reviews the mechanism of cytotoxicity related to mitochondrial dysfunction after fluorosis. A series of mitochondrial dysfunction caused by fluorosis, such as mitochondrial dynamics, mitochondrial Reactive oxygen species, mitochondrial fission, mitochondrial respiratory chain, mitochondrial autophagy apoptosis, mitochondrial fusion disturbance, mitochondrial calcium regulation are emphasized, and the mechanism of the effect of fluoride on cytotoxicity related to mitochondrial dysfunction are further explored.
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Affiliation(s)
- Mingbang Wei
- College of Animal Science, Tibet Agriculture and Animal Husbandry College, Linzhi, China.,The Provincial and Ministerial Co-founded Collaborative Innovation Center for R&D in Tibet Characteristic Agricultural and Animal Husbandry Resources, Linzhi, China
| | - Yourong Ye
- College of Animal Science, Tibet Agriculture and Animal Husbandry College, Linzhi, China.,The Provincial and Ministerial Co-founded Collaborative Innovation Center for R&D in Tibet Characteristic Agricultural and Animal Husbandry Resources, Linzhi, China
| | - Muhammad Muddassir Ali
- Institute of Biochemistry and Biotechnology, University of Veterinary and Animal Sciences, Lahore, Pakistan
| | - Yangzom Chamba
- College of Animal Science, Tibet Agriculture and Animal Husbandry College, Linzhi, China.,The Provincial and Ministerial Co-founded Collaborative Innovation Center for R&D in Tibet Characteristic Agricultural and Animal Husbandry Resources, Linzhi, China
| | - Jia Tang
- College of Animal Science, Tibet Agriculture and Animal Husbandry College, Linzhi, China.,The Provincial and Ministerial Co-founded Collaborative Innovation Center for R&D in Tibet Characteristic Agricultural and Animal Husbandry Resources, Linzhi, China
| | - Peng Shang
- College of Animal Science, Tibet Agriculture and Animal Husbandry College, Linzhi, China.,The Provincial and Ministerial Co-founded Collaborative Innovation Center for R&D in Tibet Characteristic Agricultural and Animal Husbandry Resources, Linzhi, China
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4
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Dvorak V, Wiedmer T, Ingles-Prieto A, Altermatt P, Batoulis H, Bärenz F, Bender E, Digles D, Dürrenberger F, Heitman LH, IJzerman AP, Kell DB, Kickinger S, Körzö D, Leippe P, Licher T, Manolova V, Rizzetto R, Sassone F, Scarabottolo L, Schlessinger A, Schneider V, Sijben HJ, Steck AL, Sundström H, Tremolada S, Wilhelm M, Wright Muelas M, Zindel D, Steppan CM, Superti-Furga G. An Overview of Cell-Based Assay Platforms for the Solute Carrier Family of Transporters. Front Pharmacol 2021; 12:722889. [PMID: 34447313 PMCID: PMC8383457 DOI: 10.3389/fphar.2021.722889] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Accepted: 07/19/2021] [Indexed: 12/12/2022] Open
Abstract
The solute carrier (SLC) superfamily represents the biggest family of transporters with important roles in health and disease. Despite being attractive and druggable targets, the majority of SLCs remains understudied. One major hurdle in research on SLCs is the lack of tools, such as cell-based assays to investigate their biological role and for drug discovery. Another challenge is the disperse and anecdotal information on assay strategies that are suitable for SLCs. This review provides a comprehensive overview of state-of-the-art cellular assay technologies for SLC research and discusses relevant SLC characteristics enabling the choice of an optimal assay technology. The Innovative Medicines Initiative consortium RESOLUTE intends to accelerate research on SLCs by providing the scientific community with high-quality reagents, assay technologies and data sets, and to ultimately unlock SLCs for drug discovery.
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Affiliation(s)
- Vojtech Dvorak
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria
| | - Tabea Wiedmer
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria
| | - Alvaro Ingles-Prieto
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria
| | | | - Helena Batoulis
- Drug Discovery Sciences–Lead Discovery, Bayer Pharmaceuticals, Wuppertal, Germany
| | - Felix Bärenz
- Sanofi-Aventis Deutschland GmbH, Frankfurt am Main, Germany
| | - Eckhard Bender
- Drug Discovery Sciences–Lead Discovery, Bayer Pharmaceuticals, Wuppertal, Germany
| | - Daniela Digles
- Department of Pharmaceutical Sciences, University of Vienna, Vienna, Austria
| | | | - Laura H. Heitman
- Division of Drug Discovery and Safety, LACDR, Leiden University, Leiden, Netherlands
| | - Adriaan P. IJzerman
- Division of Drug Discovery and Safety, LACDR, Leiden University, Leiden, Netherlands
| | - Douglas B. Kell
- Department of Biochemistry and Systems Biology, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, United Kingdom
- Novo Nordisk Foundation Centre for Biosustainability, Technical University of Denmark, Kgs. Lyngby, Denmark
| | - Stefanie Kickinger
- Department of Pharmaceutical Sciences, University of Vienna, Vienna, Austria
| | - Daniel Körzö
- Department of Pharmaceutical Sciences, University of Vienna, Vienna, Austria
| | - Philipp Leippe
- Department of Chemical Biology, Max Planck Institute for Medical Research, Heidelberg, Germany
| | - Thomas Licher
- Sanofi-Aventis Deutschland GmbH, Frankfurt am Main, Germany
| | | | | | | | | | - Avner Schlessinger
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, United States
| | - Vanessa Schneider
- Department of Pharmaceutical Sciences, University of Vienna, Vienna, Austria
| | - Hubert J. Sijben
- Division of Drug Discovery and Safety, LACDR, Leiden University, Leiden, Netherlands
| | | | | | | | | | - Marina Wright Muelas
- Department of Biochemistry and Systems Biology, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, United Kingdom
| | - Diana Zindel
- Drug Discovery Sciences–Lead Discovery, Bayer Pharmaceuticals, Wuppertal, Germany
| | - Claire M. Steppan
- Pfizer Worldwide Research, Development and Medical, Groton, MA, United States
| | - Giulio Superti-Furga
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria
- Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
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5
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Gueven N, Ravishankar P, Eri R, Rybalka E. Idebenone: When an antioxidant is not an antioxidant. Redox Biol 2020; 38:101812. [PMID: 33254077 PMCID: PMC7708875 DOI: 10.1016/j.redox.2020.101812] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 11/16/2020] [Accepted: 11/23/2020] [Indexed: 02/06/2023] Open
Abstract
Idebenone is a well described drug that was initially developed against dementia. The current literature widely portrays this molecule as a potent antioxidant and CoQ10 analogue. While numerous papers seem to support this view, a closer look indicates that the pharmacokinetics of idebenone do not support these claims. A major discrepancy between achievable tissue levels, especially in target tissues such as the brain, and doses required to show the proposed effects, significantly questions our current understanding. This review explains how this has happened and highlights the discrepancies in the current literature. More importantly, based on some recent discoveries, a new framework is presented that can explain the mode of action of this molecule and can align formerly contradictory results. Finally, this new appreciation of the molecular activities of idebenone provides a rational approach to test idebenone in novel indications that might have not been considered previously for this drug.
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Affiliation(s)
- Nuri Gueven
- School of Pharmacy and Pharmacology, College of Health and Medicine, University of Tasmania, Hobart, TAS, Australia.
| | - Pranathi Ravishankar
- School of Pharmacy and Pharmacology, College of Health and Medicine, University of Tasmania, Hobart, TAS, Australia
| | - Rajaraman Eri
- School of Health Sciences, College of Health and Medicine, University of Tasmania, Launceston, TAS, Australia
| | - Emma Rybalka
- Victoria University, Institute for Health and Sport, Melbourne, Victoria, Australia
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6
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Electrophysiology Measurements of Metal Transport by MntH2 from Enterococcus faecalis. MEMBRANES 2020; 10:membranes10100255. [PMID: 32987882 PMCID: PMC7599946 DOI: 10.3390/membranes10100255] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 09/16/2020] [Accepted: 09/22/2020] [Indexed: 12/30/2022]
Abstract
Transition metals are essential trace elements and their high-affinity uptake is required for many organisms. Metal transporters are often characterised using metal-sensitive fluorescent dyes, limiting the metals and experimental conditions that can be studied. Here, we have tested whether metal transport by Enterococcus faecalis MntH2 can be measured with an electrophysiology method that is based on the solid-supported membrane technology. E. faecalis MntH2 belongs to the Natural Resistance-Associated Macrophage Protein (Nramp) family of proton-coupled transporters, which transport divalent transition metals and do not transport the earth metals. Electrophysiology confirms transport of Mn(II), Co(II), Zn(II) and Cd(II) by MntH2. However, no uptake responses for Cu(II), Fe(II) and Ni(II) were observed, while the presence of these metals abolishes the uptake signals for Mn(II). Fluorescence assays confirm that Ni(II) is transported. The data are discussed with respect to properties and structures of Nramp-type family members and the ability of electrophysiology to measure charge transport and not directly substrate transport.
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7
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Abstract
Here, we present a protocol for the functional characterization of the H+-coupled human peptide transporter PepT1 and sufficient notes to transfer the protocol to the Na+-coupled sugar transporter SGLT1, the organic cation transporter OCT2, the Na+/Ca2+ exchanger NCX, and the neuronal glutamate transporter EAAT3.The assay was developed for the commercially available SURFE2R N1 instrument (Nanion Technologies GmbH) which applies solid supported membrane (SSM)-based electrophysiology. This technique is widely used for the functional characterization of membrane transporters with more than 100 different transporters characterized so far. The technique is cost-effective, easy to use, and capable of high-throughput measurements.SSM-based electrophysiology utilizes SSM-coated gold sensors to physically adsorb membrane vesicles containing the protein of interest. A fast solution exchange provides the substrate and activates transport. For the measurement of PepT1 activity, we applied a peptide concentration jump to activate H+/peptide symport. Proton influx charges the sensor. A capacitive current is measured reflecting the transport activity of PepT1 . Multiple measurements on the same sensor allow for comparison of transport activity under different conditions. Here, we determine EC50 for PepT1-mediated glycylglycine transport and perform an inhibition experiment using the specific peptide inhibitor Lys[Z(NO2)]-Val.
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8
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Zhao WP, Wang HW, Liu J, Zhang ZH, Zhu SQ, Zhou BH. Mitochondrial respiratory chain complex abnormal expressions and fusion disorder are involved in fluoride-induced mitochondrial dysfunction in ovarian granulosa cells. CHEMOSPHERE 2019; 215:619-625. [PMID: 30342406 DOI: 10.1016/j.chemosphere.2018.10.043] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Revised: 10/03/2018] [Accepted: 10/06/2018] [Indexed: 06/08/2023]
Abstract
Excessive fluoride intake has a strong female reproductive toxicity, which can result in follicular developmental dysplasia and decrease oocytes developmental potential. The underlying mechanisms of fluoride-induced mitochondrial dysfunction in ovarian granulosa cells remain largely unknown. In this study, the ultrastructure changes of mitochondria and DNA damage in ovarian granulosa cells were observed under transmission electron microscope and TUNEL staining. Then, the ATP content and ROS level in granulosa cells were measured. The expression of mitochondrial fusion proteins and mitochondrial respiratory chain complexes, including OPA1 and Mfn1, and NDUFV2, SDHA and CYC1, in the ovarian tissues were measured by immunohistochemistry, Western blot and Quantitative real-time PCR analyses. The expression of ATP5j and ATP5h in the ovarian tissues was also measured. Results show that fluoride treatment considerably damages mitochondrial ultrastructure and enhances the apoptosis of granulosa cells. The ATP content greatly decreased, whereas the ROS level increased after fluoride treatment. The expression level of Mfn1 in the ovarian tissue was up-regulated, whereas OPA1 expression had no significant change. The expression levels of NDUFV2, SDHA and CYC1 were considerably up-regulated, and the expression of ATP5j and ATP5h were down-regulated after fluoride treatment. In summary, the damage in the mitochondrial ultrastructure, ATP content decrease, ROS level increase and the abnormal expression of OPA1, Mfn1, NDUFV2, SDHA, CYC1, ATP5j and ATP5h in ovary tissue are closely associated with fluoride-induced mitochondrial dysfunction, which might be responsible for the follicular developmental dysplasia and the potential decrease in oocyte development induced by fluoride in female mice.
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Affiliation(s)
- Wen-Peng Zhao
- College of Animal Science and Technology, Henan University of Science and Technology, Luoyang 471000, Henan, PR China.
| | - Hong-Wei Wang
- College of Animal Science and Technology, Henan University of Science and Technology, Luoyang 471000, Henan, PR China.
| | - Jing Liu
- College of Animal Science and Technology, Henan University of Science and Technology, Luoyang 471000, Henan, PR China.
| | - Zi-Hao Zhang
- College of Animal Science and Technology, Henan University of Science and Technology, Luoyang 471000, Henan, PR China.
| | - Shi-Quan Zhu
- College of Animal Science and Technology, Henan University of Science and Technology, Luoyang 471000, Henan, PR China.
| | - Bian-Hua Zhou
- College of Animal Science and Technology, Henan University of Science and Technology, Luoyang 471000, Henan, PR China.
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Danylovych HV. Evaluation of functioning of mitochondrial electron transport chain with NADH and FAD autofluorescence. UKRAINIAN BIOCHEMICAL JOURNAL 2018; 88:31-43. [PMID: 29227076 DOI: 10.15407/ubj88.01.031] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
We prove the feasibility of evaluation of mitochondrial electron transport chain function in isolated
mitochondria of smooth muscle cells of rats from uterus using fluorescence of NADH and FAD coenzymes.
We found the inversely directed changes in FAD and NADH fluorescence intensity under normal functioning
of mitochondrial electron transport chain. The targeted effect of inhibitors of complex I, III and IV changed
fluorescence of adenine nucleotides. Rotenone (5 μM) induced rapid increase in NADH fluorescence due
to inhibition of complex I, without changing in dynamics of FAD fluorescence increase. Antimycin A, a
complex III inhibitor, in concentration of 1 μg/ml caused sharp increase in NADH fluorescence and moderate
increase in FAD fluorescence in comparison to control. NaN3 (5 mM), a complex IV inhibitor, and CCCP
(10 μM), a protonophore, caused decrease in NADH and FAD fluorescence. Moreover, all the inhibitors
caused mitochondria swelling. NO donors, e.g. 0.1 mM sodium nitroprusside and sodium nitrite similarly
to the effects of sodium azide. Energy-dependent Ca2+ accumulation in mitochondrial matrix (in presence
of oxidation substrates and Mg-ATP2- complex) is associated with pronounced drop in NADH and FAD
fluorescence followed by increased fluorescence of adenine nucleotides, which may be primarily due to Ca2+-
dependent activation of dehydrogenases of citric acid cycle. Therefore, the fluorescent signal of FAD and
NADH indicates changes in oxidation state of these nucleotides in isolated mitochondria, which may be used
to assay the potential of effectors of electron transport chain.
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10
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Abstract
Functional characterization of transport proteins using conventional electrophysiology can be challenging, especially for low turnover transporters or transporters from bacteria and intracellular compartments. Solid-supported membrane (SSM)-based electrophysiology is a sensitive and cell-free assay technique for the characterization of electrogenic membrane proteins. Purified proteins reconstituted into proteoliposomes or membrane vesicles from cell culture or native tissues are adsorbed to the sensor holding an SSM. A substrate or a ligand is applied via rapid solution exchange. The electrogenic transporter activity charges the sensor, which is recorded as a transient current. The high stability of the SSM allows cumulative measurements on the same sensor using different experimental conditions. This allows the determination of kinetic properties including EC50, IC50, Km, KD, and rate constants of electrogenic reactions. About 100 different transporters have been measured so far using this technique, among them symporters, exchangers, uniporters, ATP-, redox-, and light-driven ion pumps, as well as receptors and ion channels. Different instruments apply this technique: the laboratory setups use a closed flow-through arrangement, while the commercially available SURFE2R N1 resembles a pipetting robot. For drug screening purposes high-throughput systems, such as the SURFE2R 96SE enable the simultaneous measurement of up to 96 sensors.
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Affiliation(s)
- Andre Bazzone
- Max Planck Institute of Biophysics, Frankfurt/Main, Germany; Nanion Technologies GmbH, Munich, Germany
| | | | - Klaus Fendler
- Max Planck Institute of Biophysics, Frankfurt/Main, Germany.
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Siebels I, Dröse S. Charge translocation by mitochondrial NADH:ubiquinone oxidoreductase (complex I) from Yarrowia lipolytica measured on solid-supported membranes. Biochem Biophys Res Commun 2016; 479:277-282. [PMID: 27639643 DOI: 10.1016/j.bbrc.2016.09.059] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2016] [Accepted: 09/12/2016] [Indexed: 11/17/2022]
Abstract
The charge translocation by purified reconstituted mitochondrial complex I from the obligate aerobic yeast Yarrowia lipolytica was investigated after adsorption of proteoliposomes to solid-supported membranes. In presence of n-decylubiquinone (DBQ), pulses of NADH provided by rapid solution exchange induced charge transfer reflecting steady-state pumping activity of the reconstituted enzyme. The signal amplitude increased with time, indicating 'deactive→active' transition of the Yarrowia complex I. Furthermore, an increase of the membrane-conductivity after addition of 5-(N-ethyl-N-isopropyl)amiloride (EIPA) was detected which questiones the use of EIPA as an inhibitor of the Na+/H+-antiporter-like subunits of complex I. This investigation shows that electrical measurements on solid-supported membranes are a suitable method to analyze transport events and 'active/deactive' transition of mitochondrial complex I.
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Affiliation(s)
- Ilka Siebels
- Molecular Bioenergetics Group, Medical School, Johann Wolfgang Goethe-University, 60590, Frankfurt am Main, Germany; Goethe University Frankfurt, Institute of Organic Chemistry and Chemical Biology, Buchmann Institute for Molecular Life Sciences, Protein Reaction Control Group, Max-von-Laue-Str. 15, 60438, Frankfurt am Main, Germany
| | - Stefan Dröse
- Molecular Bioenergetics Group, Medical School, Johann Wolfgang Goethe-University, 60590, Frankfurt am Main, Germany; Department of Anesthesiology, Intensive-Care Medicine and Pain Therapy, University Hospital Frankfurt, 60590, Frankfurt am Main, Germany.
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12
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Border between natural product and drug: comparison of the related benzoquinones idebenone and coenzyme Q10. Redox Biol 2015; 4:289-95. [PMID: 25625583 PMCID: PMC4803797 DOI: 10.1016/j.redox.2015.01.009] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Revised: 01/12/2015] [Accepted: 01/12/2015] [Indexed: 12/23/2022] Open
Abstract
Coenzyme Q10 is a ubiquitous component of cellular membranes and belongs to the class of benzoquinones that mainly differ with regards to the length and composition of their hydrophobic tail. The characteristic quinone group can accept electrons from various biological sources and is converted by a one electron transfer to the unstable semiquinone or by a two electron transfer to the more stable hydroquinone. This feature makes CoQ10 the bona fide cellular electron transfer molecule within the mitochondrial respiratory chain and also makes it a potent cellular antioxidant. These activities serve as justification for its popular use as food supplement. Another quinone with similarities to the naturally occurring CoQ10 is idebenone, which shares its quinone moiety with CoQ10, but at the same time differs from CoQ10 by the presence of a much shorter, less lipophilic tail. However, despite its similarity to CoQ10, idebenone cannot be isolated from any natural sources but instead was synthesized and selected as a pharmacologically active compound in the 1980s by Takeda Pharmaceuticals purely based on its pharmacological properties. Several recent clinical trials demonstrated some therapeutic efficacy of idebenone in different indications and as a consequence, many practitioners question if the freely available CoQ10 could not be used instead. Here, we describe the molecular and pharmacological features of both molecules that arise from their structural differences to answer the question if idebenone is merely a CoQ10 analogue as frequently perpetuated in the literature or a pharmaceutical drug with entirely different features. The benzoquinones CoQ10 and idebenone have vastly different solubility. Both molecules need to get activated by cellular reductases. Due to their solubility both molecules are in different cellular compartments. Therefore, both quinones are activated by different enzymes. Thus, their solubility strongly determines their biological activities.
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13
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Bagkos G, Koufopoulos K, Piperi C. A new model for mitochondrial membrane potential production and storage. Med Hypotheses 2014; 83:175-81. [PMID: 24907229 DOI: 10.1016/j.mehy.2014.05.001] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2013] [Accepted: 05/10/2014] [Indexed: 02/05/2023]
Abstract
Mitochondrial membrane potential (MMP) is the most reliable indicator of mitochondrial function. The MMP value range of -136 to -140mV has been considered optimal for maximum ATP production for all living organisms. Even small changes from the above range result in a large fall in ATP production and a large increase in ROS production. The resulting bioenergetic deregulation is considered as the causative agent for numerous major human diseases. Normalization of MMP value improves mitochondrial function and gives excellent therapeutic results. In order for a systematic effective treatment of these diseases to be developed, a detailed knowledge of the mechanism of MMP production is absolutely necessary. However, despite the long-standing research efforts, a concrete mechanism for MMP production has not been found yet. The present paper proposes a novel mechanism of MMP production based on new considerations underlying the function of the two basic players of MMP production, the electron transport chain (ETC) and the F1F0 ATP synthase. Under normal conditions, MMP is almost exclusively produced by the electron flow through ETC complexes I-IV, creating a direct electric current that stops in subunit II of complex IV and gradually charges MMP. However, upon ETC dysfunction F1F0 ATP synthase reverses its action and starts to hydrolyze ATP. ATP hydrolysis further produces electric energy which is transferred, in the form of a direct electric current, from F1 to F0 where is used to charge MMP. This new model is expected to redirect current experimental research on mitochondrial bioenergetics and indicate new therapeutic schemes for mitochondrial disorders.
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Affiliation(s)
- Georgios Bagkos
- Department of Biological Chemistry, University of Athens Medical School, Athens, Greece
| | - Kostas Koufopoulos
- Department of Biological Chemistry, University of Athens Medical School, Athens, Greece
| | - Christina Piperi
- Department of Biological Chemistry, University of Athens Medical School, Athens, Greece.
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14
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Stock U, Matter H, Diekert K, Dörner W, Dröse S, Licher T. Measuring interference of drug-like molecules with the respiratory chain: toward the early identification of mitochondrial uncouplers in lead finding. Assay Drug Dev Technol 2013; 11:408-22. [PMID: 23992120 PMCID: PMC3777647 DOI: 10.1089/adt.2012.463] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The electron transport chain (ETC) couples electron transfer between donors and acceptors with proton transport across the inner mitochondrial membrane. The resulting electrochemical proton gradient is used to generate chemical energy in the form of adenosine triphosphate (ATP). Proton transfer is based on the activity of complex I-V proteins in the ETC. The overall electrical activity of these proteins can be measured by proton transfer using Solid Supported Membrane technology. We tested the activity of complexes I, III, and V in a combined assay, called oxidative phosphorylation assay (oxphos assay), by activating each complex with the corresponding substrate. The oxphos assay was used to test in-house substances from different projects and several drugs currently available on the market that have reported effects on mitochondrial functions. The resulting data were compared to the influence of the respective compounds on mitochondria as determined by oxygen consumption and to data generated with an ATP depletion assay. The comparison shows that the oxidative phosphorylation assay provides both a rapid approach for detecting interaction of compounds with respiratory chain proteins and information on their mode of interaction. Therefore, the oxphos assay is a useful tool to support structure activity relationship studies by allowing early identification of mitotoxicity and for analyzing the outcome of phenotypic screens that are susceptible to the generation of mitotoxicity-related artifacts.
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Affiliation(s)
- Ursula Stock
- R&D LGCR, Sanofi-Aventis Deutschland GmbH, Frankfurt, Germany
| | - Hans Matter
- R&D LGCR, Sanofi-Aventis Deutschland GmbH, Frankfurt, Germany
| | | | | | - Stefan Dröse
- ZBC-Molekulare Bioenergetik, Frankfurt University Hospital, Frankfurt, Germany
| | - Thomas Licher
- R&D LGCR, Sanofi-Aventis Deutschland GmbH, Frankfurt, Germany
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15
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Gueven N, Faldu D. Idebenone treatment in Leber's hereditary optic neuropathy: rationale and efficacy. Expert Opin Orphan Drugs 2013. [DOI: 10.1517/21678707.2013.772894] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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16
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Assaying the proton transport and regulation of UCP1 using solid supported membranes. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2012; 41:675-9. [PMID: 22847775 DOI: 10.1007/s00249-012-0844-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2012] [Revised: 07/02/2012] [Accepted: 07/10/2012] [Indexed: 10/28/2022]
Abstract
The uncoupling protein 1 (UCP1) is a mitochondrial protein that carries protons across the inner mitochondrial membrane. It has an important role in non-shivering thermogenesis, and recent evidence suggests its role in human adult metabolism. Using rapid solution exchange on solid supported membranes, we succeeded in measuring electrical currents generated by the transport activity of UCP1. The protein was purified from mouse brown adipose tissue, reconstituted in liposomes and absorbed on solid supported membranes. A fast pH jump activated the ion transport, and electrical signals could be recorded. The currents were characterized by a fast rise and a slow decay, were stable over time, inhibited by purine nucleotides and activated by fatty acids. This new assay permits direct observation of UCP1 activity in controlled cell-free conditions, and opens up new possibilities for UCP1 functional characterization and drug screening because of its robustness and its potential for automation.
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