101
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Schaefer PM, Hilpert D, Niederschweiberer M, Neuhauser L, Kalinina S, Calzia E, Rueck A, von Einem B, von Arnim CAF. Mitochondrial matrix pH as a decisive factor in neurometabolic imaging. NEUROPHOTONICS 2017; 4:045004. [PMID: 29181426 PMCID: PMC5685807 DOI: 10.1117/1.nph.4.4.045004] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Accepted: 10/16/2017] [Indexed: 06/07/2023]
Abstract
Alterations of cellular bioenergetics are a common feature in most neurodegenerative disorders. However, there is a selective vulnerability of different brain regions, cell types, and even mitochondrial populations to these metabolic disturbances. Thus, the aim of our study was to establish and validate an in vivo metabolic imaging technique to screen for mitochondrial function on the subcellular level. Based on nicotinamide adenine dinucleotide (phosphate) fluorescence lifetime imaging microscopy [NAD(P)H FLIM], we performed a quantitative correlation to high-resolution respirometry. Thereby, we revealed mitochondrial matrix pH as a decisive factor in imaging NAD(P)H redox state. By combining both parameters, we illustrate a quantitative, high-resolution assessment of mitochondrial function in metabolically modified cells as well as in an amyloid precursor protein-overexpressing model of Alzheimer's disease. Our metabolic imaging technique provides the basis for dissecting mitochondrial deficits not only in a range of neurodegenerative diseases, shedding light onto bioenergetic failures of cells remaining in their metabolic microenvironment.
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Affiliation(s)
| | - Diana Hilpert
- Ulm University, Department of Neurology, Ulm, Germany
| | | | | | - Sviatlana Kalinina
- Ulm University, Core Facility Confocal and Multiphoton Microscopy, Ulm, Germany
| | - Enrico Calzia
- University Medical School, Institute of Anesthesiological Pathophysiology and Process Engineering, Ulm, Germany
| | - Angelika Rueck
- Ulm University, Core Facility Confocal and Multiphoton Microscopy, Ulm, Germany
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102
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Rebuffet E, Frick A, Järvå M, Törnroth-Horsefield S. Cell-free production and characterisation of human uncoupling protein 1-3. Biochem Biophys Rep 2017; 10:276-281. [PMID: 28955755 PMCID: PMC5614671 DOI: 10.1016/j.bbrep.2017.04.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2016] [Revised: 04/04/2017] [Accepted: 04/07/2017] [Indexed: 11/22/2022] Open
Abstract
The uncoupling proteins (UCPs) leak protons across the inner mitochondrial membrane, thus uncoupling the proton gradient from ATP synthesis. The main known physiological role for this is heat generation by UCP1 in brown adipose tissue. However, UCPs are also believed to be important for protection against reactive oxygen species, fine-tuning of metabolism and have been suggested to be involved in disease states such as obesity, diabetes and cancer. Structural studies of UCPs have long been hampered by difficulties in sample preparation with neither expression in yeast nor refolding from inclusion bodies in E. coli yielding sufficient amounts of pure and stable protein. In this study, we have developed a protocol for cell-free expression of human UCP1, 2 and 3, resulting in 1 mg pure protein per 20 mL of expression media. Lauric acid, a natural UCP ligand, significantly improved protein thermal stability and was therefore added during purification. Secondary structure characterisation using circular dichroism spectroscopy revealed the proteins to consist of mostly α-helices, as expected. All three UCPs were able to bind GDP, a well-known physiological inhibitor, as shown by the Fluorescence Resonance Energy Transfer (FRET) technique, suggesting that the proteins are in a natively folded state. A protocol for cell-free expression of human uncoupling protein 1–3 is described. Addition of native membrane components increased expression levels. Addition of lauric acid increased protein stability in solution. CD spectroscopy confirms alpha-helical secondary structure as expected. All proteins binds GDP as demonstrated by Fluorescence Resonance Energy Transfer.
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Affiliation(s)
- Etienne Rebuffet
- Department of Chemistry and Molecular Biology, University of Gothenburg, Box 462, SE-405 30 Gothenburg, Sweden
| | - Anna Frick
- Department of Chemistry and Molecular Biology, University of Gothenburg, Box 462, SE-405 30 Gothenburg, Sweden
| | - Michael Järvå
- Department of Chemistry and Molecular Biology, University of Gothenburg, Box 462, SE-405 30 Gothenburg, Sweden
| | - Susanna Törnroth-Horsefield
- Department of Chemistry and Molecular Biology, University of Gothenburg, Box 462, SE-405 30 Gothenburg, Sweden.,Department of Biochemistry and Structural Biology, Centre for Molecular Protein Science, Lund University, Box 124, 221 00 Lund, Sweden
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103
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Aroca A, Schneider M, Scheibe R, Gotor C, Romero LC. Hydrogen Sulfide Regulates the Cytosolic/Nuclear Partitioning of Glyceraldehyde-3-Phosphate Dehydrogenase by Enhancing its Nuclear Localization. PLANT & CELL PHYSIOLOGY 2017; 58:983-992. [PMID: 28444344 DOI: 10.1093/pcp/pcx056] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Accepted: 04/13/2017] [Indexed: 05/18/2023]
Abstract
Hydrogen sulfide is an important signaling molecule comparable with nitric oxide and hydrogen peroxide in plants. The underlying mechanism of its action is unknown, although it has been proposed to be S-sulfhydration. This post-translational modification converts the thiol groups of cysteines within proteins to persulfides, resulting in functional changes of the proteins. In Arabidopsis thaliana, S-sulfhydrated proteins have been identified, including the cytosolic isoforms of glyceraldehyde-3-phosphate dehydrogenase GapC1 and GapC2. In this work, we studied the regulation of sulfide on the subcellular localization of these proteins using two different approaches. We generated GapC1-green fluorescent protein (GFP) and GapC2-GFP transgenic plants in both the wild type and the des1 mutant defective in the l-cysteine desulfhydrase DES1, responsible for the generation of sulfide in the cytosol. The GFP signal was detected in the cytoplasm and the nucleus of epidermal cells, although with reduced nuclear localization in des1 compared with the wild type, and exogenous sulfide treatment resulted in similar signals in nuclei in both backgrounds. The second approach consisted of the immunoblot analysis of the GapC endogenous proteins in enriched nuclear and cytosolic protein extracts, and similar results were obtained. A significant reduction in the total amount of GapC in des1 in comparison with the wild type was determined and exogenous sulfide significantly increased the protein levels in the nuclei in both plants, with a stronger response in the wild type. Moreover, the presence of an S-sulfhydrated cysteine residue on GapC1 was demonstrated by mass spectrometry. We conclude that sulfide enhances the nuclear localization of glyceraldehyde-3-phosphate dehydrogenase.
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Affiliation(s)
- Angeles Aroca
- Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Científicas y Universidad de Sevilla, Sevilla, Spain
| | - Markus Schneider
- Department of Plant Physiology, Osnabrück University, Osnabrück, Germany
| | - Renate Scheibe
- Department of Plant Physiology, Osnabrück University, Osnabrück, Germany
| | - Cecilia Gotor
- Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Científicas y Universidad de Sevilla, Sevilla, Spain
| | - Luis C Romero
- Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Científicas y Universidad de Sevilla, Sevilla, Spain
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104
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Dynamical Approach to Multi-Equilibria Problems Considering the Debye–Hückel Theory of Electrolyte Solutions: Concentration Quotients as a Function of Ionic Strength. J SOLUTION CHEM 2017. [DOI: 10.1007/s10953-017-0593-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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105
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Dong Z, Shanmughapriya S, Tomar D, Siddiqui N, Lynch S, Nemani N, Breves SL, Zhang X, Tripathi A, Palaniappan P, Riitano MF, Worth AM, Seelam A, Carvalho E, Subbiah R, Jaña F, Soboloff J, Peng Y, Cheung JY, Joseph SK, Caplan J, Rajan S, Stathopulos PB, Madesh M. Mitochondrial Ca 2+ Uniporter Is a Mitochondrial Luminal Redox Sensor that Augments MCU Channel Activity. Mol Cell 2017; 65:1014-1028.e7. [PMID: 28262504 DOI: 10.1016/j.molcel.2017.01.032] [Citation(s) in RCA: 169] [Impact Index Per Article: 24.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2016] [Revised: 12/02/2016] [Accepted: 01/26/2017] [Indexed: 12/13/2022]
Abstract
Ca2+ dynamics and oxidative signaling are fundamental mechanisms for mitochondrial bioenergetics and cell function. The MCU complex is the major pathway by which these signals are integrated in mitochondria. Whether and how these coactive elements interact with MCU have not been established. As an approach toward understanding the regulation of MCU channel by oxidative milieu, we adapted inflammatory and hypoxia models. We identified the conserved cysteine 97 (Cys-97) to be the only reactive thiol in human MCU that undergoes S-glutathionylation. Furthermore, biochemical, structural, and superresolution imaging analysis revealed that MCU oxidation promotes MCU higher order oligomer formation. Both oxidation and mutation of MCU Cys-97 exhibited persistent MCU channel activity with higher [Ca2+]m uptake rate, elevated mROS, and enhanced [Ca2+]m overload-induced cell death. In contrast, these effects were largely independent of MCU interaction with its regulators. These findings reveal a distinct functional role for Cys-97 in ROS sensing and regulation of MCU activity.
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Affiliation(s)
- Zhiwei Dong
- Department of Medical Genetics and Molecular Biochemistry, Lewis Katz School of Medicine, Temple University, Philadelphia, PA 19140, USA; Center for Translational Medicine, Lewis Katz School of Medicine, Temple University, Philadelphia, PA 19140, USA; Institute of Burn Research, Southwest Hospital, Third Military Medical University, Chongqing 400038, PRC
| | - Santhanam Shanmughapriya
- Department of Medical Genetics and Molecular Biochemistry, Lewis Katz School of Medicine, Temple University, Philadelphia, PA 19140, USA; Center for Translational Medicine, Lewis Katz School of Medicine, Temple University, Philadelphia, PA 19140, USA
| | - Dhanendra Tomar
- Department of Medical Genetics and Molecular Biochemistry, Lewis Katz School of Medicine, Temple University, Philadelphia, PA 19140, USA; Center for Translational Medicine, Lewis Katz School of Medicine, Temple University, Philadelphia, PA 19140, USA
| | - Naveed Siddiqui
- Department of Physiology and Pharmacology, Western University, London, ON N6A 5C1, Canada
| | - Solomon Lynch
- Department of Biological Sciences, Delaware Biotechnology Institute, University of Delaware, Newark, DE 19711, USA
| | - Neeharika Nemani
- Department of Medical Genetics and Molecular Biochemistry, Lewis Katz School of Medicine, Temple University, Philadelphia, PA 19140, USA; Center for Translational Medicine, Lewis Katz School of Medicine, Temple University, Philadelphia, PA 19140, USA
| | - Sarah L Breves
- Department of Medical Genetics and Molecular Biochemistry, Lewis Katz School of Medicine, Temple University, Philadelphia, PA 19140, USA; Center for Translational Medicine, Lewis Katz School of Medicine, Temple University, Philadelphia, PA 19140, USA
| | - Xueqian Zhang
- Center for Translational Medicine, Lewis Katz School of Medicine, Temple University, Philadelphia, PA 19140, USA
| | - Aparna Tripathi
- Department of Medical Genetics and Molecular Biochemistry, Lewis Katz School of Medicine, Temple University, Philadelphia, PA 19140, USA; Center for Translational Medicine, Lewis Katz School of Medicine, Temple University, Philadelphia, PA 19140, USA
| | - Palaniappan Palaniappan
- Department of Medical Genetics and Molecular Biochemistry, Lewis Katz School of Medicine, Temple University, Philadelphia, PA 19140, USA; Center for Translational Medicine, Lewis Katz School of Medicine, Temple University, Philadelphia, PA 19140, USA
| | - Massimo F Riitano
- Department of Medical Genetics and Molecular Biochemistry, Lewis Katz School of Medicine, Temple University, Philadelphia, PA 19140, USA; Center for Translational Medicine, Lewis Katz School of Medicine, Temple University, Philadelphia, PA 19140, USA
| | - Alison M Worth
- Department of Medical Genetics and Molecular Biochemistry, Lewis Katz School of Medicine, Temple University, Philadelphia, PA 19140, USA; Center for Translational Medicine, Lewis Katz School of Medicine, Temple University, Philadelphia, PA 19140, USA
| | - Ajay Seelam
- Department of Medical Genetics and Molecular Biochemistry, Lewis Katz School of Medicine, Temple University, Philadelphia, PA 19140, USA; Center for Translational Medicine, Lewis Katz School of Medicine, Temple University, Philadelphia, PA 19140, USA
| | - Edmund Carvalho
- Department of Medical Genetics and Molecular Biochemistry, Lewis Katz School of Medicine, Temple University, Philadelphia, PA 19140, USA; Center for Translational Medicine, Lewis Katz School of Medicine, Temple University, Philadelphia, PA 19140, USA
| | - Ramasamy Subbiah
- Department of Medical Genetics and Molecular Biochemistry, Lewis Katz School of Medicine, Temple University, Philadelphia, PA 19140, USA; Center for Translational Medicine, Lewis Katz School of Medicine, Temple University, Philadelphia, PA 19140, USA
| | - Fabián Jaña
- Department of Medical Genetics and Molecular Biochemistry, Lewis Katz School of Medicine, Temple University, Philadelphia, PA 19140, USA; Center for Translational Medicine, Lewis Katz School of Medicine, Temple University, Philadelphia, PA 19140, USA
| | - Jonathan Soboloff
- Department of Medical Genetics and Molecular Biochemistry, Lewis Katz School of Medicine, Temple University, Philadelphia, PA 19140, USA
| | - Yizhi Peng
- Institute of Burn Research, Southwest Hospital, Third Military Medical University, Chongqing 400038, PRC
| | - Joseph Y Cheung
- Center for Translational Medicine, Lewis Katz School of Medicine, Temple University, Philadelphia, PA 19140, USA
| | - Suresh K Joseph
- MitoCare Center, Department of Pathology, Anatomy, and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Jeffrey Caplan
- Department of Biological Sciences, Delaware Biotechnology Institute, University of Delaware, Newark, DE 19711, USA
| | - Sudarsan Rajan
- Department of Medical Genetics and Molecular Biochemistry, Lewis Katz School of Medicine, Temple University, Philadelphia, PA 19140, USA; Center for Translational Medicine, Lewis Katz School of Medicine, Temple University, Philadelphia, PA 19140, USA.
| | - Peter B Stathopulos
- Department of Physiology and Pharmacology, Western University, London, ON N6A 5C1, Canada
| | - Muniswamy Madesh
- Department of Medical Genetics and Molecular Biochemistry, Lewis Katz School of Medicine, Temple University, Philadelphia, PA 19140, USA; Center for Translational Medicine, Lewis Katz School of Medicine, Temple University, Philadelphia, PA 19140, USA.
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106
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Vatrinet R, Leone G, De Luise M, Girolimetti G, Vidone M, Gasparre G, Porcelli AM. The α-ketoglutarate dehydrogenase complex in cancer metabolic plasticity. Cancer Metab 2017; 5:3. [PMID: 28184304 PMCID: PMC5289018 DOI: 10.1186/s40170-017-0165-0] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Accepted: 01/18/2017] [Indexed: 02/07/2023] Open
Abstract
Deregulated metabolism is a well-established hallmark of cancer. At the hub of various metabolic pathways deeply integrated within mitochondrial functions, the α-ketoglutarate dehydrogenase complex represents a major modulator of electron transport chain activity and tricarboxylic acid cycle (TCA) flux, and is a pivotal enzyme in the metabolic reprogramming following a cancer cell’s change in bioenergetic requirements. By contributing to the control of α-ketoglutarate levels, dynamics, and oxidation state, the α-ketoglutarate dehydrogenase is also essential in modulating the epigenetic landscape of cancer cells. In this review, we will discuss the manifold roles that this TCA enzyme and its substrate play in cancer.
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Affiliation(s)
- Renaud Vatrinet
- Dipartimento Farmacia e Biotecnologie (FABIT), Università di Bologna, Via Selmi 3, 40126 Bologna, Italy.,Dipartimento Scienze Mediche e Chirurgiche (DIMEC), U.O. Genetica Medica, Pol. Universitario S. Orsola-Malpighi, Università di Bologna, Via Massarenti 9, 40138 Bologna, Italy
| | - Giulia Leone
- Dipartimento Farmacia e Biotecnologie (FABIT), Università di Bologna, Via Selmi 3, 40126 Bologna, Italy
| | - Monica De Luise
- Dipartimento Scienze Mediche e Chirurgiche (DIMEC), U.O. Genetica Medica, Pol. Universitario S. Orsola-Malpighi, Università di Bologna, Via Massarenti 9, 40138 Bologna, Italy
| | - Giulia Girolimetti
- Dipartimento Scienze Mediche e Chirurgiche (DIMEC), U.O. Genetica Medica, Pol. Universitario S. Orsola-Malpighi, Università di Bologna, Via Massarenti 9, 40138 Bologna, Italy
| | - Michele Vidone
- Dipartimento Scienze Mediche e Chirurgiche (DIMEC), U.O. Genetica Medica, Pol. Universitario S. Orsola-Malpighi, Università di Bologna, Via Massarenti 9, 40138 Bologna, Italy
| | - Giuseppe Gasparre
- Dipartimento Scienze Mediche e Chirurgiche (DIMEC), U.O. Genetica Medica, Pol. Universitario S. Orsola-Malpighi, Università di Bologna, Via Massarenti 9, 40138 Bologna, Italy
| | - Anna Maria Porcelli
- Dipartimento Farmacia e Biotecnologie (FABIT), Università di Bologna, Via Selmi 3, 40126 Bologna, Italy
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107
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Hardonnière K, Huc L, Sergent O, Holme JA, Lagadic-Gossmann D. Environmental carcinogenesis and pH homeostasis: Not only a matter of dysregulated metabolism. Semin Cancer Biol 2017; 43:49-65. [PMID: 28088583 DOI: 10.1016/j.semcancer.2017.01.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Revised: 01/05/2017] [Accepted: 01/05/2017] [Indexed: 12/18/2022]
Abstract
According to the World Health Organization, around 20% of all cancers would be due to environmental factors. Among these factors, several chemicals are indeed well recognized carcinogens. The widespread contaminant benzo[a]pyrene (B[a]P), an often used model carcinogen of the polycyclic aromatic hydrocarbons' family, has been suggested to target most, if not all, cancer hallmarks described by Hanahan and Weinberg. It is classified as a group I carcinogen by the International Agency for Research on Cancer; however, the precise intracellular mechanisms underlying its carcinogenic properties remain yet to be thoroughly defined. Recently, the pH homeostasis, a well known regulator of carcinogenic processes, was suggested to be a key actor in both cell death and Warburg-like metabolic reprogramming induced upon B[a]P exposure. The present review will highlight those data with the aim of favoring research on the role of H+ dynamics in environmental carcinogenesis.
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Affiliation(s)
- Kévin Hardonnière
- Institut national de la santé et de la recherche médicale (Inserm), Institut de recherche en santé, environnement et travail (Irset - Inserm UMR 1085), F-35043 Rennes, France; Université de Rennes 1, Structure fédérative de recherche Biosit, UMS CNRS 3480/US Inserm 018, F 35043 Rennes, France
| | - Laurence Huc
- INRA UMR 1331 ToxAlim (Research Center in Food Toxicology), University of Toulouse ENVT, INP, UPS, 180 Chemin de Tournefeuille, F-31027, France
| | - Odile Sergent
- Institut national de la santé et de la recherche médicale (Inserm), Institut de recherche en santé, environnement et travail (Irset - Inserm UMR 1085), F-35043 Rennes, France; Université de Rennes 1, Structure fédérative de recherche Biosit, UMS CNRS 3480/US Inserm 018, F 35043 Rennes, France
| | - Jørn A Holme
- Domain of Infection Control, Environment and Health, Norwegian Institute of Public Health, Oslo, Norway
| | - Dominique Lagadic-Gossmann
- Institut national de la santé et de la recherche médicale (Inserm), Institut de recherche en santé, environnement et travail (Irset - Inserm UMR 1085), F-35043 Rennes, France; Université de Rennes 1, Structure fédérative de recherche Biosit, UMS CNRS 3480/US Inserm 018, F 35043 Rennes, France.
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108
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Zhang Y, Avalos JL. Traditional and novel tools to probe the mitochondrial metabolism in health and disease. WILEY INTERDISCIPLINARY REVIEWS-SYSTEMS BIOLOGY AND MEDICINE 2017; 9. [PMID: 28067471 DOI: 10.1002/wsbm.1373] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Revised: 11/07/2016] [Accepted: 11/09/2016] [Indexed: 02/06/2023]
Abstract
Mitochondrial metabolism links energy production to other essential cellular processes such as signaling, cellular differentiation, and apoptosis. In addition to producing adenosine triphosphate (ATP) as an energy source, mitochondria are responsible for the synthesis of a myriad of important metabolites and cofactors such as tetrahydrofolate, α-ketoacids, steroids, aminolevulinic acid, biotin, lipoic acid, acetyl-CoA, iron-sulfur clusters, heme, and ubiquinone. Furthermore, mitochondria and their metabolism have been implicated in aging and several human diseases, including inherited mitochondrial disorders, cardiac dysfunction, heart failure, neurodegenerative diseases, diabetes, and cancer. Therefore, there is great interest in understanding mitochondrial metabolism and the complex relationship it has with other cellular processes. A large number of studies on mitochondrial metabolism have been conducted in the last 50 years, taking a broad range of approaches. In this review, we summarize and discuss the most commonly used tools that have been used to study different aspects of the metabolism of mitochondria: ranging from dyes that monitor changes in the mitochondrial membrane potential and pharmacological tools to study respiration or ATP synthesis, to more modern tools such as genetically encoded biosensors and trans-omic approaches enabled by recent advances in mass spectrometry, computation, and other technologies. These tools have allowed the large number of studies that have shaped our current understanding of mitochondrial metabolism. WIREs Syst Biol Med 2017, 9:e1373. doi: 10.1002/wsbm.1373 For further resources related to this article, please visit the WIREs website.
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Affiliation(s)
- Yanfei Zhang
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ, USA
| | - José L Avalos
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ, USA.,Andlinger Center for Energy and the Environment, Princeton University, Princeton, NJ, USA.,Department of Molecular Biology, Princeton University, Princeton, NJ, USA
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109
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Lee CP, Maksaev G, Jensen GS, Murcha MW, Wilson ME, Fricker M, Hell R, Haswell ES, Millar AH, Sweetlove LJ. MSL1 is a mechanosensitive ion channel that dissipates mitochondrial membrane potential and maintains redox homeostasis in mitochondria during abiotic stress. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2016; 88:809-825. [PMID: 27505616 PMCID: PMC5195915 DOI: 10.1111/tpj.13301] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Revised: 08/04/2016] [Accepted: 08/05/2016] [Indexed: 05/18/2023]
Abstract
Mitochondria must maintain tight control over the electrochemical gradient across their inner membrane to allow ATP synthesis while maintaining a redox-balanced electron transport chain and avoiding excessive reactive oxygen species production. However, there is a scarcity of knowledge about the ion transporters in the inner mitochondrial membrane that contribute to control of membrane potential. We show that loss of MSL1, a member of a family of mechanosensitive ion channels related to the bacterial channel MscS, leads to increased membrane potential of Arabidopsis mitochondria under specific bioenergetic states. We demonstrate that MSL1 localises to the inner mitochondrial membrane. When expressed in Escherichia coli, MSL1 forms a stretch-activated ion channel with a slight preference for anions and provides protection against hypo-osmotic shock. In contrast, loss of MSL1 in Arabidopsis did not prevent swelling of isolated mitochondria in hypo-osmotic conditions. Instead, our data suggest that ion transport by MSL1 leads to dissipation of mitochondrial membrane potential when it becomes too high. The importance of MSL1 function was demonstrated by the observation of a higher oxidation state of the mitochondrial glutathione pool in msl1-1 mutants under moderate heat- and heavy-metal-stress. Furthermore, we show that MSL1 function is not directly implicated in mitochondrial membrane potential pulsing, but is complementary and appears to be important under similar conditions.
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Affiliation(s)
- Chun Pong Lee
- ARC Centre of Excellence in Plant Energy Biology, University of Western Australia, Bayliss Building M316, 35 Stirling Highway, Crawley, 6009, Western Australia, Australia
| | - Grigory Maksaev
- Department of Biology, Washington University in Saint Louis, One Brookings Drive, Mailcode 1137, Saint Louis, MO, 63130, USA
| | - Gregory S Jensen
- Department of Biology, Washington University in Saint Louis, One Brookings Drive, Mailcode 1137, Saint Louis, MO, 63130, USA
| | - Monika W Murcha
- ARC Centre of Excellence in Plant Energy Biology, University of Western Australia, Bayliss Building M316, 35 Stirling Highway, Crawley, 6009, Western Australia, Australia
| | - Margaret E Wilson
- Department of Biology, Washington University in Saint Louis, One Brookings Drive, Mailcode 1137, Saint Louis, MO, 63130, USA
| | - Mark Fricker
- Department of Plant Sciences, University of Oxford, South Parks Road, Oxford, OX1 3RB, UK
| | - Ruediger Hell
- Department of Plant Molecular Biology, Centre for Organismal Studies, University of Heidelberg, Im Neuenheimer Feld 360, D-69120, Heidelberg, Germany
| | - Elizabeth S Haswell
- Department of Biology, Washington University in Saint Louis, One Brookings Drive, Mailcode 1137, Saint Louis, MO, 63130, USA
| | - A Harvey Millar
- ARC Centre of Excellence in Plant Energy Biology, University of Western Australia, Bayliss Building M316, 35 Stirling Highway, Crawley, 6009, Western Australia, Australia
| | - Lee J Sweetlove
- Department of Plant Sciences, University of Oxford, South Parks Road, Oxford, OX1 3RB, UK
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110
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Pham TD, Pham PQ, Li J, Letai AG, Wallace DC, Burke PJ. Cristae remodeling causes acidification detected by integrated graphene sensor during mitochondrial outer membrane permeabilization. Sci Rep 2016; 6:35907. [PMID: 27786282 PMCID: PMC5081517 DOI: 10.1038/srep35907] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Accepted: 10/07/2016] [Indexed: 12/31/2022] Open
Abstract
The intrinsic apoptotic pathway and the resultant mitochondrial outer membrane permeabilization (MOMP) via BAK and BAX oligomerization, cytochrome c (cytc) release, and caspase activation are well studied, but their effect on cytosolic pH is poorly understood. Using isolated mitochondria, we show that MOMP results in acidification of the surrounding medium. BAK conformational changes associated with MOMP activate the OMA1 protease to cleave OPA1 resulting in remodeling of the cristae and release of the highly concentrated protons within the cristae invaginations. This was revealed by utilizing a nanomaterial graphene as an optically clear and ultrasensitive pH sensor that can measure ionic changes induced by tethered mitochondria. With this platform, we have found that activation of mitochondrial apoptosis is accompanied by a gradual drop in extra-mitochondrial pH and a decline in membrane potential, both of which can be rescued by adding exogenous cytc. These findings have importance for potential pharmacological manipulation of apoptosis, in the treatment of cancer.
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Affiliation(s)
- Ted D. Pham
- Department of Biomedical Engineering, University of California, Irvine, CA, USA
| | - Phi Q. Pham
- Department of Chemical Engineering and Materials Science, University of California, Irvine, CA, USA
| | - Jinfeng Li
- Department of Chemical Engineering and Materials Science, University of California, Irvine, CA, USA
| | - Anthony G. Letai
- Dana-Farber Cancer Institute, Harvard University, Boston, MA, USA
| | - Douglas C. Wallace
- Center for Mitochondrial and Epigenomic Medicine, Children’s Hospital of Philadelphia and Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Peter J. Burke
- Department of Biomedical Engineering, University of California, Irvine, CA, USA
- Department of Chemical Engineering and Materials Science, University of California, Irvine, CA, USA
- Department of Electrical Engineering and Computer Science, University of California, Irvine, CA, USA
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111
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Spectroscopic characterization of genotoxic chromium(V) peptide complexes: Oxidation of Chromium(III) triglycine, tetraglycine and pentaglycine complexes. J Inorg Biochem 2016; 162:227-237. [DOI: 10.1016/j.jinorgbio.2016.06.015] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2015] [Revised: 06/07/2016] [Accepted: 06/14/2016] [Indexed: 11/23/2022]
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112
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Zhang J, Liu Z, Lian P, Qian J, Li X, Wang L, Fu W, Chen L, Wei X, Li C. Selective imaging and cancer cell death via pH switchable near-infrared fluorescence and photothermal effects. Chem Sci 2016; 7:5995-6005. [PMID: 30034741 PMCID: PMC6022192 DOI: 10.1039/c6sc00221h] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2016] [Accepted: 05/23/2016] [Indexed: 01/23/2023] Open
Abstract
Accurately locating and eradicating sporadically distributed cancer cells whilst minimizing damage to adjacent normal tissues is vital in image-guided tumor ablation. In this work, we developed four heptamethine cyanine based theranostic probes, IR1-4, that demonstrated unique pH switchable near-infrared (NIR) fluorescence and photothermal efficiency. While their fluorescence quantum yields increased up to 1020-fold upon acidification from pH 7.4 to 2.4, their photothermal efficiencies decreased up to 7.1-fold concomitantly. Theoretical calculations showed that protonation of the probes in an acidic environment increased the orbital energy gaps and reduced the intramolecular charge transfer efficiency, resulting in the conversion of absorbed light energy to NIR fluorescence instead of hyperthermia. Substitutions at the terminal indole of the probes fine-tuned their pKafluo values to a narrow physiological pH range of 4.0-5.3. IR2, with a pKafluo of 4.6, not only specifically illuminated cancer cells by sensing their more acidic lysosomal lumen, but also selectively ablated cancer cells via its maximized photothermal effects in the alkaline mitochondrial matrix. As far as we are aware, these probes not only offer the highest physiological acidity triggered NIR fluorescence enhancement as small molecules, but are also the first to specifically visualize and eradicate cancer cells by sensing their altered pH values in cellular organelles. Considering that a disordered pH in organelle lumen is a common characteristic of cancer cells, these theranostic probes hold the promise to be applied in image-guided tumor ablation over a wide range of tumor subtypes.
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Affiliation(s)
- Jingye Zhang
- Key Laboratory of Smart Drug Delivery , Ministry of Education , School of Pharmacy , Fudan University , Shanghai 201203 , China .
| | - Zining Liu
- Key Laboratory of Smart Drug Delivery , Ministry of Education , School of Pharmacy , Fudan University , Shanghai 201203 , China .
| | - Peng Lian
- Key Laboratory of Smart Drug Delivery , Ministry of Education , School of Pharmacy , Fudan University , Shanghai 201203 , China .
| | - Jun Qian
- Key Laboratory of Smart Drug Delivery , Ministry of Education , School of Pharmacy , Fudan University , Shanghai 201203 , China .
| | - Xinwei Li
- Key Laboratory of Smart Drug Delivery , Ministry of Education , School of Pharmacy , Fudan University , Shanghai 201203 , China .
| | - Lu Wang
- Department of Chemistry , National University of Singapore , Singapore 117543 , Singapore
| | - Wei Fu
- Key Laboratory of Smart Drug Delivery , Ministry of Education , School of Pharmacy , Fudan University , Shanghai 201203 , China .
| | - Liang Chen
- Department of Neurosurgery , Huashan Hospital , Fudan University , Shanghai 200040 , China
| | - Xunbin Wei
- State Key Laboratory of Oncogenes and Related Genes , Shanghai Cancer Institute , School of Biomedical Engineering , Shanghai Jiao Tong University , 1954 Huashan Road , Shanghai , 200030 , China .
| | - Cong Li
- Key Laboratory of Smart Drug Delivery , Ministry of Education , School of Pharmacy , Fudan University , Shanghai 201203 , China .
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113
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The effect of chronic alcohol consumption on mitochondrial calcium handling in hepatocytes. Biochem J 2016; 473:3903-3921. [PMID: 27582500 DOI: 10.1042/bcj20160255] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Accepted: 08/31/2016] [Indexed: 01/08/2023]
Abstract
The damage to liver mitochondria is universally observed in both humans and animal models after excessive alcohol consumption. Acute alcohol treatment has been shown to stimulate calcium (Ca2+) release from internal stores in hepatocytes. The resultant increase in cytosolic Ca2+ is expected to be accumulated by neighboring mitochondria, which could potentially lead to mitochondrial Ca2+ overload and injury. Our data indicate that total and free mitochondrial matrix Ca2+ levels are, indeed, elevated in hepatocytes isolated from alcohol-fed rats compared with their pair-fed control littermates. In permeabilized hepatocytes, the rates of mitochondrial Ca2+ uptake were substantially increased after chronic alcohol feeding, whereas those of mitochondrial Ca2+ efflux were decreased. The changes in mitochondrial Ca2+ handling could be explained by an up-regulation of the mitochondrial Ca2+ uniporter and loss of a cyclosporin A-sensitive Ca2+ transport pathway. In intact cells, hormone-induced increases in mitochondrial Ca2+ declined at slower rates leading to more prolonged elevations of matrix Ca2+ in the alcohol-fed group compared with controls. Moreover, treatment with submaximal concentrations of Ca2+-mobilizing hormones markedly increased the levels of mitochondrial reactive oxygen species (ROS) in hepatocytes from alcohol-fed rats, but did not affect ROS levels in controls. The changes in mitochondrial Ca2+ handling are expected to buffer and attenuate cytosolic Ca2+ increases induced by acute alcohol exposure or hormone stimulation. However, these alterations in mitochondrial Ca2+ handling may also lead to Ca2+ overload during cytosolic Ca2+ increases, which may stimulate the production of mitochondrial ROS, and thus contribute to alcohol-induced liver injury.
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114
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Epi-reevesioside F inhibits Na+/K+-ATPase, causing cytosolic acidification, Bak activation and apoptosis in glioblastoma. Oncotarget 2016; 6:24032-46. [PMID: 26125228 PMCID: PMC4695168 DOI: 10.18632/oncotarget.4429] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2015] [Accepted: 06/04/2015] [Indexed: 12/17/2022] Open
Abstract
Epi-reevesioside F, a new cardiac glycoside isolated from the root of Reevesia formosana, displayed potent activity against glioblastoma cells. Epi-reevesioside F was more potent than ouabain with IC50 values of 27.3±1.7 vs. 48.7±1.8 nM (P < 0.001) and 45.0±3.4 vs. 81.3±4.3 nM (P < 0.001) in glioblastoma T98 and U87 cells, respectively. However, both Epi-reevesioside F and ouabain were ineffective in A172 cells, a glioblastoma cell line with low Na+/K+-ATPase α3 subunit expression. Epi-reevesioside F induced cell cycle arrest at S and G2 phases and apoptosis. It also induced an increase of intracellular concentration of Na+ but not Ca2+, cleavage and exposure of N-terminus of Bak, loss of mitochondrial membrane potential, inhibition of Akt activity and induction of caspase cascades. Potassium supplements significantly inhibited Epi-reevesioside F-induced effects. Notably, Epi-reevesioside F caused cytosolic acidification that was highly correlated with the anti-proliferative activity. In summary, the data suggest that Epi-reevesioside F inhibits Na+/K+-ATPase, leading to overload of intracellular Na+ and cytosolic acidification, Bak activation and loss of mitochondrial membrane potential. The PI3-kinase/Akt pathway is inhibited and caspase-dependent apoptosis is ultimately triggered in Epi-reevesioside F-treated glioblastoma cells.
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115
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Lee CP, Millar AH. The Plant Mitochondrial Transportome: Balancing Metabolic Demands with Energetic Constraints. TRENDS IN PLANT SCIENCE 2016; 21:662-676. [PMID: 27162080 DOI: 10.1016/j.tplants.2016.04.003] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2016] [Revised: 03/25/2016] [Accepted: 04/04/2016] [Indexed: 06/05/2023]
Abstract
In plants, mitochondrial function is associated with hundreds of metabolic reactions. To facilitate these reactions, charged substrates and cofactors move across the charge-impermeable inner mitochondrial membrane via specialized transporters and must work cooperatively with the electrochemical gradient which is essential for mitochondrial function. The regulatory framework for mitochondrial metabolite transport is expected to be more complex in plants than in mammals owing to the close metabolic association between mitochondrial, plastids, and peroxisome metabolism, as well as to the major diurnal fluctuations in plant metabolic function. We propose here how recent advances can be integrated towards defining the mitochondrial transportome in plants. We also discuss what this reveals about sustaining cooperativity between bioenergetics, metabolism, and transport in typical and challenging environments.
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Affiliation(s)
- Chun Pong Lee
- Australian Reseach Council (ARC) Centre of Excellence in Plant Energy Biology, The University of Western Australia, 35 Stirling Highway, Crawley 6009, Australia
| | - A Harvey Millar
- Australian Reseach Council (ARC) Centre of Excellence in Plant Energy Biology, The University of Western Australia, 35 Stirling Highway, Crawley 6009, Australia.
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116
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Ippolito JE, Brandenburg MW, Ge X, Crowley JR, Kirmess KM, Som A, D’Avignon DA, Arbeit JM, Achilefu S, Yarasheski KE, Milbrandt J. Extracellular pH Modulates Neuroendocrine Prostate Cancer Cell Metabolism and Susceptibility to the Mitochondrial Inhibitor Niclosamide. PLoS One 2016; 11:e0159675. [PMID: 27438712 PMCID: PMC4954648 DOI: 10.1371/journal.pone.0159675] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2016] [Accepted: 07/06/2016] [Indexed: 01/07/2023] Open
Abstract
Neuroendocrine prostate cancer is a lethal variant of prostate cancer that is associated with castrate-resistant growth, metastasis, and mortality. The tumor environment of neuroendocrine prostate cancer is heterogeneous and characterized by hypoxia, necrosis, and numerous mitoses. Although acidic extracellular pH has been implicated in aggressive cancer features including metastasis and therapeutic resistance, its role in neuroendocrine prostate cancer physiology and metabolism has not yet been explored. We used the well-characterized PNEC cell line as a model to establish the effects of extracellular pH (pH 6.5, 7.4, and 8.5) on neuroendocrine prostate cancer cell metabolism. We discovered that alkalinization of extracellular pH converted cellular metabolism to a nutrient consumption-dependent state that was susceptible to glucose deprivation, glutamine deprivation, and 2-deoxyglucose (2-DG) mediated inhibition of glycolysis. Conversely, acidic pH shifted cellular metabolism toward an oxidative phosphorylation (OXPHOS)-dependent state that was susceptible to OXPHOS inhibition. Based upon this mechanistic knowledge of pH-dependent metabolism, we identified that the FDA-approved anti-helminthic niclosamide depolarized mitochondrial potential and depleted ATP levels in PNEC cells whose effects were enhanced in acidic pH. To further establish relevance of these findings, we tested the effects of extracellular pH on susceptibility to nutrient deprivation and OXPHOS inhibition in a cohort of castrate-resistant prostate cancer cell lines C4-2B, PC-3, and PC-3M. We discovered similar pH-dependent toxicity profiles among all cell lines with these treatments. These findings underscore a potential importance to acidic extracellular pH in the modulation of cell metabolism in tumors and development of an emerging paradigm that exploits the synergy of environment and therapeutic efficacy in cancer.
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Affiliation(s)
- Joseph E. Ippolito
- Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
- Department of Genetics, Washington University School of Medicine, St. Louis, Missouri, United States of America
- * E-mail:
| | - Matthew W. Brandenburg
- Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
- Department of Genetics, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Xia Ge
- Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Jan R. Crowley
- Biomedical Mass Spectrometry Resource, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Kristopher M. Kirmess
- Biomedical Mass Spectrometry Resource, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Avik Som
- Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - D. Andre D’Avignon
- Sanford Burnham Prebys Medical Discovery Institute, Orlando, Florida, United States of America
| | - Jeffrey M. Arbeit
- Department of Surgery, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Samuel Achilefu
- Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Kevin E. Yarasheski
- Biomedical Mass Spectrometry Resource, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Jeffrey Milbrandt
- Department of Genetics, Washington University School of Medicine, St. Louis, Missouri, United States of America
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117
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Bal NC, Maurya SK, Singh S, Wehrens XHT, Periasamy M. Increased Reliance on Muscle-based Thermogenesis upon Acute Minimization of Brown Adipose Tissue Function. J Biol Chem 2016; 291:17247-57. [PMID: 27298322 DOI: 10.1074/jbc.m116.728188] [Citation(s) in RCA: 70] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Indexed: 12/22/2022] Open
Abstract
Skeletal muscle has been suggested as a site of nonshivering thermogenesis (NST) besides brown adipose tissue (BAT). Studies in birds, which do not contain BAT, have demonstrated the importance of skeletal muscle-based NST. However, muscle-based NST in mammals remains poorly characterized. We recently reported that sarco/endoplasmic reticulum Ca(2+) cycling and that its regulation by SLN can be the basis for muscle NST. Because of the dominant role of BAT-mediated thermogenesis in rodents, the role of muscle-based NST is less obvious. In this study, we investigated whether muscle will become an important site of NST when BAT function is conditionally minimized in mice. We surgically removed interscapular BAT (iBAT, which constitutes ∼70% of total BAT) and exposed the mice to prolonged cold (4 °C) for 9 days. The iBAT-ablated mice were able to maintain optimal body temperature (∼35-37 °C) during the entire period of cold exposure. After 4 days in the cold, both sham controls and iBAT-ablated mice stopped shivering and resumed routine physical activity, indicating that they are cold-adapted. The iBAT-ablated mice showed higher oxygen consumption and decreased body weight and fat mass, suggesting an increased energy cost of cold adaptation. The skeletal muscles in these mice underwent extensive remodeling of both the sarcoplasmic reticulum and mitochondria, including alteration in the expression of key components of Ca(2+) handling and mitochondrial metabolism. These changes, along with increased sarcolipin expression, provide evidence for the recruitment of NST in skeletal muscle. These studies collectively suggest that skeletal muscle becomes the major site of NST when BAT activity is minimized.
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Affiliation(s)
- Naresh C Bal
- From the Sanford Burnham Prebys Medical Discovery Institute at Lake Nona, Orlando, Florida 32827, the Department of Physiology and Cell Biology, College of Medicine, Ohio State University, Columbus, Ohio 43210, the School of Biotechnology, KIIT University, Bhubaneswar, Odisha, India 751024, and
| | - Santosh K Maurya
- From the Sanford Burnham Prebys Medical Discovery Institute at Lake Nona, Orlando, Florida 32827, the Department of Physiology and Cell Biology, College of Medicine, Ohio State University, Columbus, Ohio 43210
| | - Sushant Singh
- From the Sanford Burnham Prebys Medical Discovery Institute at Lake Nona, Orlando, Florida 32827, the Department of Physiology and Cell Biology, College of Medicine, Ohio State University, Columbus, Ohio 43210
| | - Xander H T Wehrens
- the Cardiovascular Research Institute, Departments of Molecular Physiology and Biophysics, Medicine, and Pediatrics, Baylor College of Medicine, Houston, Texas 77030
| | - Muthu Periasamy
- From the Sanford Burnham Prebys Medical Discovery Institute at Lake Nona, Orlando, Florida 32827, the Department of Physiology and Cell Biology, College of Medicine, Ohio State University, Columbus, Ohio 43210
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118
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Wagner S, De Bortoli S, Schwarzländer M, Szabò I. Regulation of mitochondrial calcium in plants versus animals. JOURNAL OF EXPERIMENTAL BOTANY 2016; 67:3809-29. [PMID: 27001920 DOI: 10.1093/jxb/erw100] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Ca(2+) acts as an important cellular second messenger in eukaryotes. In both plants and animals, a wide variety of environmental and developmental stimuli trigger Ca(2+) transients of a specific signature that can modulate gene expression and metabolism. In animals, mitochondrial energy metabolism has long been considered a hotspot of Ca(2+) regulation, with a range of pathophysiology linked to altered Ca(2+) control. Recently, several molecular players involved in mitochondrial Ca(2+) signalling have been identified, including those of the mitochondrial Ca(2+) uniporter. Despite strong evidence for sophisticated Ca(2+) regulation in plant mitochondria, the picture has remained much less clear. This is currently changing aided by live imaging and genetic approaches which allow dissection of subcellular Ca(2+) dynamics and identification of the proteins involved. We provide an update on our current understanding in the regulation of mitochondrial Ca(2+) and signalling by comparing work in plants and animals. The significance of mitochondrial Ca(2+) control is discussed in the light of the specific metabolic and energetic needs of plant and animal cells.
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Affiliation(s)
- Stephan Wagner
- Plant Energy Biology Lab, Institute of Crop Science and Resource Conservation (INRES), University of Bonn, Friedrich-Ebert-Allee 144, D-53113 Bonn, Germany
| | - Sara De Bortoli
- Department of Biology and CNR Institute of Neurosciences, University of Padova, Viale G. Colombo 3, 35121 Padova, Italy
| | - Markus Schwarzländer
- Plant Energy Biology Lab, Institute of Crop Science and Resource Conservation (INRES), University of Bonn, Friedrich-Ebert-Allee 144, D-53113 Bonn, Germany
| | - Ildikò Szabò
- Department of Biology and CNR Institute of Neurosciences, University of Padova, Viale G. Colombo 3, 35121 Padova, Italy
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119
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Structures of Human Peroxiredoxin 3 Suggest Self-Chaperoning Assembly that Maintains Catalytic State. Structure 2016; 24:1120-9. [PMID: 27238969 DOI: 10.1016/j.str.2016.04.013] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Revised: 03/14/2016] [Accepted: 04/09/2016] [Indexed: 01/05/2023]
Abstract
Peroxiredoxins are antioxidant proteins primarily responsible for detoxification of hydroperoxides in cells. On exposure to various cellular stresses, peroxiredoxins can acquire chaperone activity, manifested as quaternary reorganization into a high molecular weight (HMW) form. Acidification, for example, causes dodecameric rings of human peroxiredoxin 3 (HsPrx3) to stack into long helical filaments. In this work, a 4.1-Å resolution structure of low-pH-instigated helical filaments was elucidated, showing a locally unfolded active site and partially folded C terminus. A 2.8-Å crystal structure of HsPrx3 was determined at pH 8.5 under reducing conditions, wherein dodecameric rings are arranged as a short stack, with symmetry similar to low-pH filaments. In contrast to previous observations, the crystal structure displays both a fully folded active site and ordered C terminus, suggesting that the HsPrx3 HMW form maintains catalytic activity. We propose a new role for the HMW form as a self-chaperoning assembly maintaining HsPrx3 function under stress.
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120
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MCUR1 Is a Scaffold Factor for the MCU Complex Function and Promotes Mitochondrial Bioenergetics. Cell Rep 2016; 15:1673-85. [PMID: 27184846 DOI: 10.1016/j.celrep.2016.04.050] [Citation(s) in RCA: 175] [Impact Index Per Article: 21.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Revised: 03/05/2016] [Accepted: 04/12/2016] [Indexed: 11/21/2022] Open
Abstract
Mitochondrial Ca(2+) Uniporter (MCU)-dependent mitochondrial Ca(2+) uptake is the primary mechanism for increasing matrix Ca(2+) in most cell types. However, a limited understanding of the MCU complex assembly impedes the comprehension of the precise mechanisms underlying MCU activity. Here, we report that mouse cardiomyocytes and endothelial cells lacking MCU regulator 1 (MCUR1) have severely impaired [Ca(2+)]m uptake and IMCU current. MCUR1 binds to MCU and EMRE and function as a scaffold factor. Our protein binding analyses identified the minimal, highly conserved regions of coiled-coil domain of both MCU and MCUR1 that are necessary for heterooligomeric complex formation. Loss of MCUR1 perturbed MCU heterooligomeric complex and functions as a scaffold factor for the assembly of MCU complex. Vascular endothelial deletion of MCU and MCUR1 impaired mitochondrial bioenergetics, cell proliferation, and migration but elicited autophagy. These studies establish the existence of a MCU complex that assembles at the mitochondrial integral membrane and regulates Ca(2+)-dependent mitochondrial metabolism.
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121
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Jayashankar V, Mueller IA, Rafelski SM. Shaping the multi-scale architecture of mitochondria. Curr Opin Cell Biol 2016; 38:45-51. [PMID: 26907992 DOI: 10.1016/j.ceb.2016.02.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Revised: 01/21/2016] [Accepted: 02/03/2016] [Indexed: 11/25/2022]
Abstract
Mitochondria are complex organelles with a highly regulated architecture across all levels of organization. The architecture of the inner mitochondrial membrane (IMM) provides a crucial platform for many mitochondrial functions while mitochondrial network architecture is crucial for coordinating these activities throughout the cell. This review summarizes the recent findings regarding the most important shaping factors that regulate IMM organization, how IMM architecture supports bioenergetic functions and how IMM morphology adapts to meet other physiological needs of the cell. This review also highlights recent work suggesting that the functional connectivity of mitochondrial networks can be achieved not just by matrix continuity but also by inter-mitochondrial contact sites, which generate conductive continuity within a matrix-discontinuous mitochondrial network.
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Affiliation(s)
- Vaishali Jayashankar
- Department of Developmental and Cell Biology and Center for Complex Biological Systems, University of California, Irvine, CA 92697, USA
| | - Irina A Mueller
- Department of Developmental and Cell Biology and Center for Complex Biological Systems, University of California, Irvine, CA 92697, USA
| | - Susanne M Rafelski
- Department of Developmental and Cell Biology and Center for Complex Biological Systems, University of California, Irvine, CA 92697, USA.
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122
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Sarkar AR, Heo CH, Xu L, Lee HW, Si HY, Byun JW, Kim HM. A ratiometric two-photon probe for quantitative imaging of mitochondrial pH values. Chem Sci 2016; 7:766-773. [PMID: 29896360 PMCID: PMC5953010 DOI: 10.1039/c5sc03708e] [Citation(s) in RCA: 88] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Accepted: 10/27/2015] [Indexed: 01/19/2023] Open
Abstract
Mitochondrial pH (pHmito) is known to be alkaline (near 8.0) and has emerged as a potential factor for mitochondrial function and disorder. We have developed a ratiometric two-photon probe (CMP1) for quantitative analysis of pHmito in live cells and tissues. This probe is designed to function by controlling the intramolecular charge transfer from 2-naphthol, having an ideal pKa value (7.86 ± 0.05) in the cells to monitor pHmito. This transition results in a marked yellow to red emission color change in response to pH alterations from 6.0 to 9.0. CMP1 exhibits easy loading, selective and robust staining ability of mitochondria, low cytotoxicity, and bright two-photon excited fluorescence in situ, thereby allowing quantitative imaging of the pHmito in live cells and tissues. The ratiometric TPM imaging clearly reveals that subcellular distribution of the pHmito values is heterogeneous, with the pHmito values in the perinuclear region being higher than those at the periphery of the cells. The changes of pHmito values on carbonyl cyanide m-chlorophenyl hydrazone (CCCP) treatment and autophagic processes were also investigated along with their morphological alterations at specific subcellular positions. We also used CMP1 to visualize the pHmito values of Parkinson's disease model astrocytes as well as living hippocampal tissues. Our results demonstrate that CMP1 will be useful as a quantitative imaging probe to study pHmito in biomedical research.
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Affiliation(s)
- Avik Ranjan Sarkar
- Department of Chemistry and Department of Energy Systems Research , Ajou University , Suwon 443-749 , Korea .
| | - Cheol Ho Heo
- Department of Chemistry and Department of Energy Systems Research , Ajou University , Suwon 443-749 , Korea .
| | - Lei Xu
- Department of Chemistry and Department of Energy Systems Research , Ajou University , Suwon 443-749 , Korea .
| | - Hyo Won Lee
- Department of Chemistry and Department of Energy Systems Research , Ajou University , Suwon 443-749 , Korea .
| | - Ho Young Si
- Department of Chemistry and Department of Energy Systems Research , Ajou University , Suwon 443-749 , Korea .
| | - Ji Won Byun
- Department of Chemistry and Department of Energy Systems Research , Ajou University , Suwon 443-749 , Korea .
| | - Hwan Myung Kim
- Department of Chemistry and Department of Energy Systems Research , Ajou University , Suwon 443-749 , Korea .
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123
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Olsen S, Baranov MS, Baleeva NS, Antonova MM, Johnson KA, Solntsev KM. pH-Sensitive fluorophores from locked GFP chromophores by a non-alternant analogue of the photochemical meta effect. Phys Chem Chem Phys 2016; 18:26703-26711. [DOI: 10.1039/c6cp02423h] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report the synthesis and characterization of a pH-sensitive fluorescence switch based on a conformationally-locked green fluorescent protein (GFP) chromophore.
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Affiliation(s)
- Seth Olsen
- School of Mathematics and Physics
- The University of Queensland
- Brisbane
- Australia
| | - Mikhail S. Baranov
- Institute of Bioorganic Chemistry
- Russian Academy of Sciences
- 117997 Moscow
- Russia
- Pirogov Russian National Research Medical University
| | - Nadezhda S. Baleeva
- Institute of Bioorganic Chemistry
- Russian Academy of Sciences
- 117997 Moscow
- Russia
- Pirogov Russian National Research Medical University
| | - Maria M. Antonova
- Institute of Bioorganic Chemistry
- Russian Academy of Sciences
- 117997 Moscow
- Russia
| | - Kenneth A. Johnson
- Institute for Cellular and Molecular Biology
- The University of Texas at Austin
- USA
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124
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Santo-Domingo J, Wiederkehr A, De Marchi U. Modulation of the matrix redox signaling by mitochondrial Ca 2+. World J Biol Chem 2015; 6:310-323. [PMID: 26629314 PMCID: PMC4657127 DOI: 10.4331/wjbc.v6.i4.310] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Revised: 09/04/2015] [Accepted: 10/13/2015] [Indexed: 02/05/2023] Open
Abstract
Mitochondria sense, shape and integrate signals, and thus function as central players in cellular signal transduction. Ca2+ waves and redox reactions are two such intracellular signals modulated by mitochondria. Mitochondrial Ca2+ transport is of utmost physio-pathological relevance with a strong impact on metabolism and cell fate. Despite its importance, the molecular nature of the proteins involved in mitochondrial Ca2+ transport has been revealed only recently. Mitochondrial Ca2+ promotes energy metabolism through the activation of matrix dehydrogenases and down-stream stimulation of the respiratory chain. These changes also alter the mitochondrial NAD(P)H/NAD(P)+ ratio, but at the same time will increase reactive oxygen species (ROS) production. Reducing equivalents and ROS are having opposite effects on the mitochondrial redox state, which are hard to dissect. With the recent development of genetically encoded mitochondrial-targeted redox-sensitive sensors, real-time monitoring of matrix thiol redox dynamics has become possible. The discoveries of the molecular nature of mitochondrial transporters of Ca2+ combined with the utilization of the novel redox sensors is shedding light on the complex relation between mitochondrial Ca2+ and redox signals and their impact on cell function. In this review, we describe mitochondrial Ca2+ handling, focusing on a number of newly identified proteins involved in mitochondrial Ca2+ uptake and release. We further discuss our recent findings, revealing how mitochondrial Ca2+ influences the matrix redox state. As a result, mitochondrial Ca2+ is able to modulate the many mitochondrial redox-regulated processes linked to normal physiology and disease.
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125
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Hidouri S. Possible domestication of uranium oxides using biological assistance reduction. Saudi J Biol Sci 2015; 24:1-10. [PMID: 28053564 PMCID: PMC5198920 DOI: 10.1016/j.sjbs.2015.09.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Revised: 09/03/2015] [Accepted: 09/06/2015] [Indexed: 11/27/2022] Open
Abstract
Uranium has been defined in material research engineering field as one of the most energetic radioactive elements in the entire Mendeleev periodic table. The manipulation of uranium needs higher theories and sophisticated apparatus even in nuclear energy extraction or in many other chemical applications. Above the nuclear exploitation level, the chemical conventional approaches used, require a higher temperature and pressure to control the destination of ionic form. However, it has been discovered later that at biological scale, the manipulation of this actinide is possible under friendly conditions. The review summarizes the relevant properties of uranium element and a brief characterization of nanoparticles, based on some structural techniques. These techniques reveal the common link between chemical approaches and biological assistance in nanoparticles. Also, those biological entities have been able to get it after reduction. Uranium is known for its ability to destroy ductile materials. So, if biological cell can really reduce uranium, then how does it work?
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Affiliation(s)
- Slah Hidouri
- Department of Research in Sciences of Life and Materials, B6 Section, Faculty of Sciences of Bizerte, Carthage University, Jarzouna 7021, Tunisia
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126
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NH4(+) triggers the release of astrocytic lactate via mitochondrial pyruvate shunting. Proc Natl Acad Sci U S A 2015; 112:11090-5. [PMID: 26286989 DOI: 10.1073/pnas.1508259112] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Neural activity is accompanied by a transient mismatch between local glucose and oxygen metabolism, a phenomenon of physiological and pathophysiological importance termed aerobic glycolysis. Previous studies have proposed glutamate and K(+) as the neuronal signals that trigger aerobic glycolysis in astrocytes. Here we used a panel of genetically encoded FRET sensors in vitro and in vivo to investigate the participation of NH4(+), a by-product of catabolism that is also released by active neurons. Astrocytes in mixed cortical cultures responded to physiological levels of NH4(+) with an acute rise in cytosolic lactate followed by lactate release into the extracellular space, as detected by a lactate-sniffer. An acute increase in astrocytic lactate was also observed in acute hippocampal slices exposed to NH4(+) and in the somatosensory cortex of anesthetized mice in response to i.v. NH4(+). Unexpectedly, NH4(+) had no effect on astrocytic glucose consumption. Parallel measurements showed simultaneous cytosolic pyruvate accumulation and NADH depletion, suggesting the involvement of mitochondria. An inhibitor-stop technique confirmed a strong inhibition of mitochondrial pyruvate uptake that can be explained by mitochondrial matrix acidification. These results show that physiological NH4(+) diverts the flux of pyruvate from mitochondria to lactate production and release. Considering that NH4(+) is produced stoichiometrically with glutamate during excitatory neurotransmission, we propose that NH4(+) behaves as an intercellular signal and that pyruvate shunting contributes to aerobic lactate production by astrocytes.
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127
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Yeste M, Fernández-Novell JM, Ramió-Lluch L, Estrada E, Rocha LG, Cebrián-Pérez JA, Muiño-Blanco T, Concha II, Ramírez A, Rodríguez-Gil JE. Intracellular calcium movements of boar spermatozoa during 'in vitro' capacitation and subsequent acrosome exocytosis follow a multiple-storage place, extracellular calcium-dependent model. Andrology 2015; 3:729-47. [PMID: 26097097 DOI: 10.1111/andr.12054] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2015] [Revised: 04/20/2015] [Accepted: 04/25/2015] [Indexed: 01/12/2023]
Abstract
This work analysed intracellular calcium stores of boar spermatozoa subjected to 'in vitro' capacitation (IVC) and subsequent progesterone-induced acrosome exocytosis (IVAE). Intracellular calcium was analysed through two calcium markers with different physico-chemical properties, Fluo-3 and Rhod-5N. Indicative parameters of IVC and IVAE were also evaluated. Fluo-3 was located at both the midpiece and the whole head. Rhod-5N was present at the sperm head. This distribution did not change in any of the assayed conditions. Induction of IVC was concomitant with an increase in both head and midpiece Ca(2+) signals. Additionally, while IVC induction was concurrent with a significant (p < 0.05) increase in sperm membrane permeability, no significant changes were observed in O2 consumption and ATP levels. Incubation of boar spermatozoa in the absence of calcium showed a loss of both Ca(2+) labellings concomitantly with the sperm's inability to achieve IVC. The absence of extracellular calcium also induced a severe decrease in the percentage of spermatozoa exhibiting high mitochondrial membrane potential (hMMP). The IVAE was accompanied by a fast increase in both Ca(2+) signalling in control spermatozoa. These peaks were either not detected or much lessened in the absence of calcium. Remarkably, Fluo-3 marking at the midpiece increased after progesterone addition to sperm cells incubated in a medium without Ca(2+) . The simultaneous addition of progesterone with the calcium chelant EGTA inhibited IVAE, and this was accompanied by a significant (p < 0.05) decrease in the intensity of progesterone Ca(2+) -induced peak, O2 consumption and ATP levels. Our results suggest that boar spermatozoa present different calcium deposits with a dynamic equilibrium among them and with the extracellular environment. Additionally, the modulation role of the intracellular calcium in spermatozoa function seems to rely on its precise localization in boar spermatozoa.
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Affiliation(s)
- M Yeste
- Department of Animal Medicine and Surgery, Faculty of Veterinary Medicine, Autonomous University of Barcelona, Bellaterra (Cerdanyola del Vallès), Spain.,Nuffield Department of Obstetrics and Gynaecology, University of Oxford, John Radcliffe Hospital, Oxford, UK
| | - J M Fernández-Novell
- Department of Biochemistry and Molecular Biology, University of Barcelona, Barcelona, Spain
| | - L Ramió-Lluch
- Department of Animal Medicine and Surgery, Faculty of Veterinary Medicine, Autonomous University of Barcelona, Bellaterra (Cerdanyola del Vallès), Spain
| | - E Estrada
- Department of Animal Medicine and Surgery, Faculty of Veterinary Medicine, Autonomous University of Barcelona, Bellaterra (Cerdanyola del Vallès), Spain
| | - L G Rocha
- Department of Animal Medicine and Surgery, Faculty of Veterinary Medicine, Autonomous University of Barcelona, Bellaterra (Cerdanyola del Vallès), Spain
| | - J A Cebrián-Pérez
- Department of Biochemistry and Molecular and Cell Biology, IUCA, School of Veterinary Medicine, University of Zaragoza-IUCA, Zaragoza, Spain
| | - T Muiño-Blanco
- Department of Biochemistry and Molecular and Cell Biology, IUCA, School of Veterinary Medicine, University of Zaragoza-IUCA, Zaragoza, Spain
| | - I I Concha
- Institute of Biochemistry and Microbiology and Institute of Animal Science, Universidad Austral de Chile, Valdivia, Chile
| | - A Ramírez
- Institute of Biochemistry and Microbiology and Institute of Animal Science, Universidad Austral de Chile, Valdivia, Chile
| | - J E Rodríguez-Gil
- Department of Animal Medicine and Surgery, Faculty of Veterinary Medicine, Autonomous University of Barcelona, Bellaterra (Cerdanyola del Vallès), Spain
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128
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Novel Paraoxonase 2-Dependent Mechanism Mediating the Biological Effects of the Pseudomonas aeruginosa Quorum-Sensing Molecule N-(3-Oxo-Dodecanoyl)-L-Homoserine Lactone. Infect Immun 2015; 83:3369-80. [PMID: 26056385 DOI: 10.1128/iai.00141-15] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Accepted: 06/05/2015] [Indexed: 11/20/2022] Open
Abstract
Pseudomonas aeruginosa produces N-(3-oxo-dodecanoyl)-L-homoserine lactone (3OC12), a crucial signaling molecule that elicits diverse biological responses in host cells thought to subvert immune defenses. The mechanism mediating many of these responses remains unknown. The intracellular lactonase paraoxonase 2 (PON2) hydrolyzes and inactivates 3OC12 and is therefore considered a component of host cells that attenuates 3OC12-mediated responses. Here, we demonstrate in cell lines and in primary human bronchial epithelial cells that 3OC12 is rapidly hydrolyzed intracellularly by PON2 to 3OC12 acid, which becomes trapped and accumulates within the cells. Subcellularly, 3OC12 acid accumulated within the mitochondria, a compartment where PON2 is localized. Treatment with 3OC12 caused a rapid PON2-dependent cytosolic and mitochondrial pH decrease, calcium release, and phosphorylation of stress signaling kinases. The results indicate a novel, PON2-dependent intracellular acidification mechanism by which 3OC12 can mediate its biological effects. Thus, PON2 is a central regulator of host cell responses to 3OC12, acting to decrease the availability of 3OC12 for receptor-mediated effects and acting to promote effects, such as calcium release and stress signaling, via intracellular acidification.
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129
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Morais MAB, Giuseppe PO, Souza TACB, Alegria TGP, Oliveira MA, Netto LES, Murakami MT. How pH modulates the dimer-decamer interconversion of 2-Cys peroxiredoxins from the Prx1 subfamily. J Biol Chem 2015; 290:8582-90. [PMID: 25666622 DOI: 10.1074/jbc.m114.619205] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
2-Cys peroxiredoxins belonging to the Prx1 subfamily are Cys-based peroxidases that control the intracellular levels of H2O2 and seem to assume a chaperone function under oxidative stress conditions. The regulation of their peroxidase activity as well as the observed functional switch from peroxidase to chaperone involves changes in their quaternary structure. Multiple factors can modulate the oligomeric transitions of 2-Cys peroxiredoxins such as redox state, post-translational modifications, and pH. However, the molecular basis for the pH influence on the oligomeric state of these enzymes is still elusive. Herein, we solved the crystal structure of a typical 2-Cys peroxiredoxin from Leishmania in the dimeric (pH 8.5) and decameric (pH 4.4) forms, showing that conformational changes in the catalytic loop are associated with the pH-induced decamerization. Mutagenesis and biophysical studies revealed that a highly conserved histidine (His(113)) functions as a pH sensor that, at acidic conditions, becomes protonated and forms an electrostatic pair with Asp(76) from the catalytic loop, triggering the decamerization. In these 2-Cys peroxiredoxins, decamer formation is important for the catalytic efficiency and has been associated with an enhanced sensitivity to oxidative inactivation by overoxidation of the peroxidatic cysteine. In eukaryotic cells, exposure to high levels of H2O2 can trigger intracellular pH variations, suggesting that pH changes might act cooperatively with H2O2 and other oligomerization-modulator factors to regulate the structure and function of typical 2-Cys peroxiredoxins in response to oxidative stress.
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Affiliation(s)
- Mariana A B Morais
- From the Laboratório Nacional de Biociências, Centro Nacional de Pesquisa em Energia e Materiais, Campinas/SP, 13083-970
| | - Priscila O Giuseppe
- From the Laboratório Nacional de Biociências, Centro Nacional de Pesquisa em Energia e Materiais, Campinas/SP, 13083-970
| | - Tatiana A C B Souza
- the Laboratório de Proteômica e Engenharia de Proteínas, Instituto Carlos Chagas, Fiocruz, Curitiba/PR, 81350-010
| | - Thiago G P Alegria
- the Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo, São Paulo/SP, 05508-900, and
| | - Marcos A Oliveira
- the Departamento de Biologia, Universidade Estadual Paulista Júlio de Mesquita Filho, Campus do Litoral Paulista, São Vicente/SP 11330-900, Brazil
| | - Luis E S Netto
- the Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo, São Paulo/SP, 05508-900, and
| | - Mario T Murakami
- From the Laboratório Nacional de Biociências, Centro Nacional de Pesquisa em Energia e Materiais, Campinas/SP, 13083-970,
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130
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Wang L, Zhou H, Wang Y, Cui G, Di LJ. CtBP maintains cancer cell growth and metabolic homeostasis via regulating SIRT4. Cell Death Dis 2015; 6:e1620. [PMID: 25633289 PMCID: PMC4669780 DOI: 10.1038/cddis.2014.587] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Revised: 12/11/2014] [Accepted: 12/12/2014] [Indexed: 12/18/2022]
Abstract
Cancer cells rely on glycolysis to maintain high levels of anabolism. However, the metabolism of glucose via glycolysis in cancer cells is frequently incomplete and results in the accumulation of acidic metabolites such as pyruvate and lactate. Thus, the cells have to develop strategies to alleviate the intracellular acidification and maintain the pH stability. We report here that glutamine consumption by cancer cells has an important role in releasing the acidification pressure associated with cancer cell growth. We found that the ammonia produced during glutaminolysis, a dominant glutamine metabolism pathway, is critical to resist the cytoplasmic acidification brought by the incomplete glycolysis. In addition, C-terminal-binding protein (CtBP) was found to have an essential role in promoting glutaminolysis by directly repressing the expression of SIRT4, a repressor of glutaminolysis by enzymatically modifying glutamate dehydrogenase in mitochondria, in cancer cells. The loss of CtBP in cancer cells resulted in the increased apoptosis due to intracellular acidification and the ablation of cancer cell metabolic homeostasis represented by decreased glutamine consumption, oxidative phosphorylation and ATP synthesis. Importantly, the immunohistochemistry staining showed that there was excessive expression of CtBP in tumor samples from breast cancer patients compared with surrounding non-tumor tissues, whereas SIRT4 expression in tumor tissues was abolished compared with the non-tumor tissues, suggesting CtBP-repressed SIRT4 expression contributes to the tumor growth. Therefore, our data suggest that the synergistically metabolism of glucose and glutamine in cancer cells contributes to both pH homeostasis and cell growth. At last, application of CtBP inhibitor induced the acidification and apoptosis of breast cancer cells and inhibited glutaminolysis in engrafted tumors, suggesting that CtBP can be potential therapeutic target of cancer treatment.
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Affiliation(s)
- L Wang
- University of Macau, Macau, SAR of People's Republic of China
| | - H Zhou
- School of life Sciences, Anhui Medical University, Hefei, Anhui Province, People's Republic of China
| | - Y Wang
- Institute of Chinese Medical Sciences, University of Macau, Macau, SAR of People's Republic of China
| | - G Cui
- 1] Institute of Chinese Medical Sciences, University of Macau, Macau, SAR of People's Republic of China [2] Bioengineering department, Zunyi Medical college, Zhuhai, Guangdong Province, People's Republic of China
| | - L-J Di
- University of Macau, Macau, SAR of People's Republic of China
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131
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Kane DA. Lactate oxidation at the mitochondria: a lactate-malate-aspartate shuttle at work. Front Neurosci 2014; 8:366. [PMID: 25505376 PMCID: PMC4243568 DOI: 10.3389/fnins.2014.00366] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Accepted: 10/25/2014] [Indexed: 11/30/2022] Open
Abstract
Lactate, the conjugate base of lactic acid occurring in aqueous biological fluids, has been derided as a “dead-end” waste product of anaerobic metabolism. Catalyzed by the near-equilibrium enzyme lactate dehydrogenase (LDH), the reduction of pyruvate to lactate is thought to serve to regenerate the NAD+ necessary for continued glycolytic flux. Reaction kinetics for LDH imply that lactate oxidation is rarely favored in the tissues of its own production. However, a substantial body of research directly contradicts any notion that LDH invariably operates unidirectionally in vivo. In the current Perspective, a model is forwarded in which the continuous formation and oxidation of lactate serves as a mitochondrial electron shuttle, whereby lactate generated in the cytosol of the cell is oxidized at the mitochondria of the same cell. From this perspective, an intracellular lactate shuttle operates much like the malate-aspartate shuttle (MAS); it is also proposed that the two shuttles are necessarily interconnected in a lactate-MAS. Among the requisite features of such a model, significant compartmentalization of LDH, much like the creatine kinase of the phosphocreatine shuttle, would facilitate net cellular lactate oxidation in a variety of cell types.
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Affiliation(s)
- Daniel A Kane
- Department of Human Kinetics, St. Francis Xavier University Antigonish, NS, Canada
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132
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Hooper SL, Burstein HJ. Minimization of extracellular space as a driving force in prokaryote association and the origin of eukaryotes. Biol Direct 2014; 9:24. [PMID: 25406691 PMCID: PMC4289276 DOI: 10.1186/1745-6150-9-24] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2014] [Accepted: 11/03/2014] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND Internalization-based hypotheses of eukaryotic origin require close physical association of host and symbiont. Prior hypotheses of how these associations arose include chance, specific metabolic couplings between partners, and prey-predator/parasite interactions. Since these hypotheses were proposed, it has become apparent that mixed-species, close-association assemblages (biofilms) are widespread and predominant components of prokaryotic ecology. Which forces drove prokaryotes to evolve the ability to form these assemblages are uncertain. Bacteria and archaea have also been found to form membrane-lined interconnections (nanotubes) through which proteins and RNA pass. These observations, combined with the structure of the nuclear envelope and an energetic benefit of close association (see below), lead us to propose a novel hypothesis of the driving force underlying prokaryotic close association and the origin of eukaryotes. RESULTS Respiratory proton transport does not alter external pH when external volume is effectively infinite. Close physical association decreases external volume. For small external volumes, proton transport decreases external pH, resulting in each transported proton increasing proton motor force to a greater extent. We calculate here that in biofilms this effect could substantially decrease how many protons need to be transported to achieve a given proton motor force. Based as it is solely on geometry, this energetic benefit would occur for all prokaryotes using proton-based respiration. CONCLUSIONS This benefit may be a driving force in biofilm formation. Under this hypothesis a very wide range of prokaryotic species combinations could serve as eukaryotic progenitors. We use this observation and the discovery of prokaryotic nanotubes to propose that eukaryotes arose from physically distinct, functionally specialized (energy factory, protein factory, DNA repository/RNA factory), obligatorily symbiotic prokaryotes in which the protein factory and DNA repository/RNA factory cells were coupled by nanotubes and the protein factory ultimately internalized the other two. This hypothesis naturally explains many aspects of eukaryotic physiology, including the nuclear envelope being a folded single membrane repeatedly pierced by membrane-bound tubules (the nuclear pores), suggests that species analogous or homologous to eukaryotic progenitors are likely unculturable as monocultures, and makes a large number of testable predictions. REVIEWERS This article was reviewed by Purificación López-García and Toni Gabaldón.
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Affiliation(s)
- Scott L Hooper
- Department of Biological Sciences, Ohio University, Athens, OH 45701 USA
| | - Helaine J Burstein
- Department of Biological Sciences, Ohio University, Athens, OH 45701 USA
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133
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Capdevila DA, Álvarez-Paggi D, Castro MA, Tórtora V, Demicheli V, Estrín DA, Radi R, Murgida DH. Coupling of tyrosine deprotonation and axial ligand exchange in nitrocytochrome c. Chem Commun (Camb) 2014; 50:2592-4. [PMID: 24471160 DOI: 10.1039/c3cc47207h] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Here we report a spectroscopic, electrochemical and computational study of cytochrome c showing that nitration of Tyr74 induces Tyr deprotonation, which is coupled to Met/Lys axial ligand exchange, and results in concomitant gain of peroxidatic activity at physiological pH.
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Affiliation(s)
- Daiana A Capdevila
- Departamento de Química Inorgánica, Analítica y Química Física and INQUIMAE, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires-CONICET, Argentina.
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134
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Rodionov RN, Jarzebska N, Weiss N, Lentz SR. AGXT2: a promiscuous aminotransferase. Trends Pharmacol Sci 2014; 35:575-82. [PMID: 25294000 DOI: 10.1016/j.tips.2014.09.005] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2014] [Revised: 09/09/2014] [Accepted: 09/11/2014] [Indexed: 12/11/2022]
Abstract
Alanine-glyoxylate aminotransferase 2 (AGXT2) is a multifunctional mitochondrial aminotransferase that was first identified in 1978. The physiological importance of AGXT2 was largely overlooked for three decades because AGXT2 is less active in glyoxylate metabolism than AGXT1, the enzyme that is deficient in primary hyperoxaluria type I. Recently, several novel functions of AGXT2 have been 'rediscovered' in the setting of modern genomic and metabolomic studies. It is now apparent that AGXT2 has multiple substrates and products and that altered AGXT2 activity may contribute to the pathogenesis of cardiovascular, renal, neurological, and hematological diseases. This article reviews the biochemical properties and physiological functions of AGXT2, its unique role at the intersection of key mitochondrial pathways, and its potential as a drug target.
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Affiliation(s)
- Roman N Rodionov
- University Center for Vascular Medicine and Department of Internal Medicine, Division of Angiology, University Hospital 'Carl Gustav Carus', Technische Universität Dresden, Fetscherstrasse 42, 01307 Dresden, Germany
| | - Natalia Jarzebska
- University Hospital 'Carl Gustav Carus', Technische Universität Dresden, Fetscherstrasse 42, 01307 Dresden, Germany
| | - Norbert Weiss
- University Center for Vascular Medicine and Department of Internal Medicine, Division of Angiology, University Hospital 'Carl Gustav Carus', Technische Universität Dresden, Fetscherstrasse 42, 01307 Dresden, Germany
| | - Steven R Lentz
- Department of Internal Medicine, University of Iowa Carver College of Medicine, 200 Hawkins Drive, Iowa City, IA 52242, USA.
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135
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Maldonado EN, Lemasters JJ. ATP/ADP ratio, the missed connection between mitochondria and the Warburg effect. Mitochondrion 2014; 19 Pt A:78-84. [PMID: 25229666 DOI: 10.1016/j.mito.2014.09.002] [Citation(s) in RCA: 123] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2014] [Revised: 09/08/2014] [Accepted: 09/08/2014] [Indexed: 02/06/2023]
Abstract
Non-proliferating cells generate the bulk of cellular ATP by fully oxidizing respiratory substrates in mitochondria. Respiratory substrates cross the mitochondrial outer membrane through only one channel, the voltage dependent anion channel (VDAC). Once in the matrix, respiratory substrates are oxidized in the tricarboxylic acid cycle to generate mostly NADH that is further oxidized in the respiratory chain to generate a proton motive force comprised mainly of membrane potential (ΔΨ) to synthesize ATP. Mitochondrial ΔΨ then drives the release of ATP(4-) from the matrix in exchange for ADP(3-) in the cytosol via the adenine nucleotide translocator (ANT) located in the mitochondrial inner membrane. Thus, mitochondrial function in non-proliferating cells drives a high cytosolic ATP/ADP ratio, essential to inhibit glycolysis. By contrast, the bioenergetics of the Warburg phenotype of proliferating cells is characterized by enhanced aerobic glycolysis and the suppression of mitochondrial metabolism. Suppressed mitochondrial function leads to lower production of mitochondrial ATP and hence lower cytosolic ATP/ADP ratios that favor enhanced glycolysis. Thus, the cytosolic ATP/ADP ratio is a key feature that determines if cell metabolism is predominantly oxidative or glycolytic. Here, we describe two novel mechanisms to explain the suppression of mitochondrial metabolism in cancer cells: the relative closure of VDAC by free tubulin and the inactivation of ANT. Both mechanisms contribute to low ATP/ADP ratios that activate glycolysis.
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Affiliation(s)
- Eduardo N Maldonado
- Center for Cell Death, Injury & Regeneration, Medical University of South Carolina, Charleston, SC 29425, United States; Department of Drug Discovery & Biomedical Sciences, Medical University of South Carolina, Charleston, SC 29425, United States; Hollings Cancer Center, Medical University of South Carolina, Charleston, SC 29425, United States
| | - John J Lemasters
- Center for Cell Death, Injury & Regeneration, Medical University of South Carolina, Charleston, SC 29425, United States; Department of Drug Discovery & Biomedical Sciences, Medical University of South Carolina, Charleston, SC 29425, United States; Department of Biochemistry & Molecular Biology, Medical University of South Carolina, Charleston, SC 29425, United States; Hollings Cancer Center, Medical University of South Carolina, Charleston, SC 29425, United States; Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Pushchino, Russia.
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136
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Ezeriņa D, Morgan B, Dick TP. Imaging dynamic redox processes with genetically encoded probes. J Mol Cell Cardiol 2014; 73:43-9. [DOI: 10.1016/j.yjmcc.2013.12.023] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2013] [Revised: 12/23/2013] [Accepted: 12/27/2013] [Indexed: 12/13/2022]
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137
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Doonan PJ, Chandramoorthy HC, Hoffman NE, Zhang X, Cárdenas C, Shanmughapriya S, Rajan S, Vallem S, Chen X, Foskett JK, Cheung JY, Houser SR, Madesh M. LETM1-dependent mitochondrial Ca2+ flux modulates cellular bioenergetics and proliferation. FASEB J 2014; 28:4936-49. [PMID: 25077561 DOI: 10.1096/fj.14-256453] [Citation(s) in RCA: 81] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Dysregulation of mitochondrial Ca(2+)-dependent bioenergetics has been implicated in various pathophysiological settings, including neurodegeneration and myocardial infarction. Although mitochondrial Ca(2+) transport has been characterized, and several molecules, including LETM1, have been identified, the functional role of LETM1-mediated Ca(2+) transport remains unresolved. This study examines LETM1-mediated mitochondrial Ca(2+) transport and bioenergetics in multiple cell types, including fibroblasts derived from patients with Wolf-Hirschhorn syndrome (WHS). The results show that both mitochondrial Ca(2+) influx and efflux rates are impaired in LETM1 knockdown, and similar phenotypes were observed in ΔEF hand, (D676A D688K)LETM1 mutant-overexpressed cells, and in cells derived from patients with WHS. Although LETM1 levels were lower in WHS-derived fibroblasts, the mitochondrial Ca(2+) uniporter components MCU, MCUR1, and MICU1 remain unaltered. In addition, the MCU mitoplast patch-clamp current (IMCU) was largely unaffected in LETM1-knockdown cells. Silencing of LETM1 also impaired basal mitochondrial oxygen consumption, possibly via complex IV inactivation and ATP production. Remarkably, LETM1 knockdown also resulted in increased reactive oxygen species production. Further, LETM1 silencing promoted AMPK activation, autophagy, and cell cycle arrest. Reconstitution of LETM1 or antioxidant overexpression rescued mitochondrial Ca(2+) transport and bioenergetics. These findings reveal the role of LETM1-dependent mitochondrial Ca(2+) flux in shaping cellular bioenergetics.
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Affiliation(s)
| | | | | | | | - César Cárdenas
- Anatomy and Developmental Biology Program, Institute of Biomedical Sciences, University of Chile, Santiago, Chile; and
| | | | - Sudarsan Rajan
- Department of Biochemistry, Center for Translational Medicine
| | - Sandhya Vallem
- Department of Biochemistry, Center for Translational Medicine
| | - Xiongwen Chen
- Cardiovascular Research Center, and Department of Physiology, Temple University School of Medicine, Philadelphia, Pennsylvania, USA
| | - J Kevin Foskett
- Department of Physiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | | | - Steven R Houser
- Cardiovascular Research Center, and Department of Physiology, Temple University School of Medicine, Philadelphia, Pennsylvania, USA
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138
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Plasma membrane Ca2+-ATPase isoforms composition regulates cellular pH homeostasis in differentiating PC12 cells in a manner dependent on cytosolic Ca2+ elevations. PLoS One 2014; 9:e102352. [PMID: 25014339 PMCID: PMC4094512 DOI: 10.1371/journal.pone.0102352] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2014] [Accepted: 06/17/2014] [Indexed: 12/14/2022] Open
Abstract
Plasma membrane Ca2+-ATPase (PMCA) by extruding Ca2+ outside the cell, actively participates in the regulation of intracellular Ca2+ concentration. Acting as Ca2+/H+ counter-transporter, PMCA transports large quantities of protons which may affect organellar pH homeostasis. PMCA exists in four isoforms (PMCA1-4) but only PMCA2 and PMCA3, due to their unique localization and features, perform more specialized function. Using differentiated PC12 cells we assessed the role of PMCA2 and PMCA3 in the regulation of intracellular pH in steady-state conditions and during Ca2+ overload evoked by 59 mM KCl. We observed that manipulation in PMCA expression elevated pHmito and pHcyto but only in PMCA2-downregulated cells higher mitochondrial pH gradient (ΔpH) was found in steady-state conditions. Our data also demonstrated that PMCA2 or PMCA3 knock-down delayed Ca2+ clearance and partially attenuated cellular acidification during KCl-stimulated Ca2+ influx. Because SERCA and NCX modulated cellular pH response in neglectable manner, and all conditions used to inhibit PMCA prevented KCl-induced pH drop, we considered PMCA2 and PMCA3 as mainly responsible for transport of protons to intracellular milieu. In steady-state conditions, higher TMRE uptake in PMCA2-knockdown line was driven by plasma membrane potential (Ψp). Nonetheless, mitochondrial membrane potential (Ψm) in this line was dissipated during Ca2+ overload. Cyclosporin and bongkrekic acid prevented Ψm loss suggesting the involvement of Ca2+-driven opening of mitochondrial permeability transition pore as putative underlying mechanism. The findings presented here demonstrate a crucial role of PMCA2 and PMCA3 in regulation of cellular pH and indicate PMCA membrane composition important for preservation of electrochemical gradient.
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139
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Doane T, Chomas A, Srinivasan S, Burda C. Observation and Photophysical Characterization of Silicon Phthalocyanine J-Aggregate Dimers in Aqueous Solutions. Chemistry 2014; 20:8030-9. [DOI: 10.1002/chem.201304885] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2013] [Indexed: 12/21/2022]
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140
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Abstract
Human mitochondria harbor an essential, high copy number, 16,569 base pair, circular DNA genome that encodes 13 gene products required for electron transport and oxidative phosphorylation. Mutation of this genome can compromise cellular respiration, ultimately resulting in a variety of progressive metabolic diseases collectively known as 'mitochondrial diseases'. Mutagenesis of mtDNA and the persistence of mtDNA mutations in cells and tissues is a complex topic, involving the interplay of DNA replication, DNA damage and repair, purifying selection, organelle dynamics, mitophagy, and aging. We briefly review these general elements that affect maintenance of mtDNA, and we focus on nuclear genes encoding the mtDNA replication machinery that can perturb the genetic integrity of the mitochondrial genome.
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Affiliation(s)
- William C Copeland
- Laboratory of Molecular Genetics, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, Durham, NC 27709, USA.
| | - Matthew J Longley
- Laboratory of Molecular Genetics, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, Durham, NC 27709, USA
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141
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Reshkin SJ, Greco MR, Cardone RA. Role of pHi, and proton transporters in oncogene-driven neoplastic transformation. Philos Trans R Soc Lond B Biol Sci 2014; 369:20130100. [PMID: 24493748 DOI: 10.1098/rstb.2013.0100] [Citation(s) in RCA: 97] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The change of a normal, healthy cell to a transformed cell is the first step in the evolutionary arc of a cancer. While the role of oncogenes in this 'passage' is well known, the role of ion transporters in this critical step is less known and is fundamental to our understanding the early physiological processes of carcinogenesis. Cancer cells and tissues have an aberrant regulation of hydrogen ion dynamics leading to a reversal of the normal tissue intracellular to extracellular pH gradient (ΔpHi to ΔpHe). When this perturbation in pH dynamics occurs during carcinogenesis is less clear. Very early studies using the introduction of different oncogene proteins into cells observed a concordance between neoplastic transformation and a cytoplasmic alkalinization occurring concomitantly with a shift towards glycolysis in the presence of oxygen, i.e. 'Warburg metabolism'. These processes may instigate a vicious cycle that drives later progression towards fully developed cancer where the reversed pH gradient becomes ever more pronounced. This review presents our understanding of the role of pH and the NHE1 in driving transformation, in determining the first appearance of the cancer 'hallmark' characteristics and how the use of pharmacological approaches targeting pH/NHE1 may open up new avenues for efficient treatments even during the first steps of cancer development.
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Affiliation(s)
- Stephan Joel Reshkin
- Department of Bioscience, Biotechnology and Biopharmaceutics, University of Bari, , Bari 70126, Italy
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142
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De Michele R, Carimi F, Frommer WB. Mitochondrial biosensors. Int J Biochem Cell Biol 2014; 48:39-44. [PMID: 24397954 DOI: 10.1016/j.biocel.2013.12.014] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2013] [Accepted: 12/26/2013] [Indexed: 10/25/2022]
Abstract
Biosensors offer an innovative tool for measuring the dynamics of a wide range of metabolites in living organisms. Biosensors are genetically encoded, and thus can be specifically targeted to specific compartments of organelles by fusion to proteins or targeting sequences. Mitochondria are central to eukaryotic cell metabolism and present a complex structure with multiple compartments. Over the past decade, genetically encoded sensors for molecules involved in energy production, reactive oxygen species and secondary messengers have helped to unravel key aspects of mitochondrial physiology. To date, sensors for ATP, NADH, pH, hydrogen peroxide, superoxide anion, redox state, cAMP, calcium and zinc have been used in the matrix, intermembrane space and in the outer membrane region of mitochondria of animal and plant cells. This review summarizes the different types of sensors employed in mitochondria and their main limits and advantages, and it provides an outlook for the future application of biosensor technology in studying mitochondrial biology.
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Affiliation(s)
- Roberto De Michele
- Institute of Biosciences and Bioresources, National Research Council of Italy (CNR-IBBR), Corso Calatafimi 414, 90129 Palermo, Italy.
| | - Francesco Carimi
- Institute of Biosciences and Bioresources, National Research Council of Italy (CNR-IBBR), Corso Calatafimi 414, 90129 Palermo, Italy
| | - Wolf B Frommer
- Department of Plant Biology, Carnegie Institute for Science, 260 Panama Street, Stanford, CA 94305, USA
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143
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Tsai MF, Jiang D, Zhao L, Clapham D, Miller C. Functional reconstitution of the mitochondrial Ca2+/H+ antiporter Letm1. ACTA ACUST UNITED AC 2013; 143:67-73. [PMID: 24344246 PMCID: PMC3874562 DOI: 10.1085/jgp.201311096] [Citation(s) in RCA: 100] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The leucine zipper, EF hand–containing transmembrane protein 1 (Letm1) gene encodes a mitochondrial inner membrane protein, whose depletion severely perturbs mitochondrial Ca2+ and K+ homeostasis. Here we expressed, purified, and reconstituted human Letm1 protein in liposomes. Using Ca2+ fluorophore and 45Ca2+-based assays, we demonstrate directly that Letm1 is a Ca2+ transporter, with apparent affinities of cations in the sequence of Ca2+ ≈ Mn2+ > Gd3+ ≈ La3+ > Sr2+ >> Ba2+, Mg2+, K+, Na+. Kinetic analysis yields a Letm1 turnover rate of 2 Ca2+/s and a Km of ∼25 µM. Further experiments show that Letm1 mediates electroneutral 1 Ca2+/2 H+ antiport. Letm1 is insensitive to ruthenium red, an inhibitor of the mitochondrial calcium uniporter, and CGP-37157, an inhibitor of the mitochondrial Na+/Ca2+ exchanger. Functional properties of Letm1 described here are remarkably similar to those of the H+-dependent Ca2+ transport mechanism identified in intact mitochondria.
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Affiliation(s)
- Ming-Feng Tsai
- Department of Biochemistry, Howard Hughes Medical Institute, Brandeis University, Waltham, MA 02454
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144
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Ghanta S, Grossmann RE, Brenner C. Mitochondrial protein acetylation as a cell-intrinsic, evolutionary driver of fat storage: chemical and metabolic logic of acetyl-lysine modifications. Crit Rev Biochem Mol Biol 2013; 48:561-74. [PMID: 24050258 DOI: 10.3109/10409238.2013.838204] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Hormone systems evolved over 500 million years of animal natural history to motivate feeding behavior and convert excess calories to fat. These systems produced vertebrates, including humans, who are famine-resistant but sensitive to obesity in environments of persistent overnutrition. We looked for cell-intrinsic metabolic features, which might have been subject to an evolutionary drive favoring lipogenesis. Mitochondrial protein acetylation appears to be such a system. Because mitochondrial acetyl-coA is the central mediator of fuel oxidation and is saturable, this metabolite is postulated to be the fundamental indicator of energy excess, which imprints a memory of nutritional imbalances by covalent modification. Fungal and invertebrate mitochondria have highly acetylated mitochondrial proteomes without an apparent mitochondrially targeted protein lysine acetyltransferase. Thus, mitochondrial acetylation is hypothesized to have evolved as a nonenzymatic phenomenon. Because the pKa of a nonperturbed Lys is 10.4 and linkage of a carbonyl carbon to an ε amino group cannot be formed with a protonated Lys, we hypothesize that acetylation occurs on residues with depressed pKa values, accounting for the propensity of acetylation to hit active sites and suggesting that regulatory Lys residues may have been under selective pressure to avoid or attract acetylation throughout animal evolution. In addition, a shortage of mitochondrial oxaloacetate under ketotic conditions can explain why macronutrient insufficiency also produces mitochondrial hyperacetylation. Reduced mitochondrial activity during times of overnutrition and undernutrition would improve fitness by virtue of resource conservation. Micronutrient insufficiency is predicted to exacerbate mitochondrial hyperacetylation. Nicotinamide riboside and Sirt3 activity are predicted to relieve mitochondrial inhibition.
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Affiliation(s)
- Sirisha Ghanta
- Department of Biochemistry, Carver College of Medicine, University of Iowa , Iowa City, IA , USA
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145
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Wang YZ, Zeng WZ, Xiao X, Huang Y, Song XL, Yu Z, Tang D, Dong XP, Zhu MX, Xu TL. Intracellular ASIC1a regulates mitochondrial permeability transition-dependent neuronal death. Cell Death Differ 2013; 20:1359-69. [PMID: 23852371 DOI: 10.1038/cdd.2013.90] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2012] [Revised: 05/12/2013] [Accepted: 06/10/2013] [Indexed: 01/08/2023] Open
Abstract
Acid-sensing ion channel 1a (ASIC1a) is the key proton receptor in nervous systems, mediating acidosis-induced neuronal injury in many neurological disorders, such as ischemic stroke. Up to now, functional ASIC1a has been found exclusively on the plasma membrane. Here, we show that ASIC1a proteins are also present in mitochondria of mouse cortical neurons where they are physically associated with adenine nucleotide translocase. Moreover, purified mitochondria from ASIC1a(-/-) mice exhibit significantly enhanced Ca(2+) retention capacity and accelerated Ca(2+) uptake rate. When challenged with hydrogen peroxide (H2O2), ASIC1a(-/-) neurons are resistant to cytochrome c release and inner mitochondrial membrane depolarization, suggesting an impairment of mitochondrial permeability transition (MPT) due to ASIC1a deletion. Consistently, H2O2-induced neuronal death, which is MPT dependent, is reduced in ASIC1a(-/-) neurons. Additionally, significant increases in mitochondrial size and oxidative stress levels are detected in ASIC1a(-/-) mouse brain, which also displays marked changes (>2-fold) in the expression of mitochondrial proteins closely related to reactive oxygen species signal pathways, as revealed by two-dimensional difference gel electrophoresis followed by mass spectrometry analysis. Our data suggest that mitochondrial ASIC1a may serve as an important regulator of MPT pores, which contributes to oxidative neuronal cell death.
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Affiliation(s)
- Y-Z Wang
- Departments of Anatomy and Embryology, Biochemistry and Molecular Cell Biology, Shanghai Key Laboratory for Tumor Microenvironment and Inflammation, Institute of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
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146
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Abstract
SIGNIFICANCE For a plant to grow and develop, energy and appropriate building blocks are a fundamental requirement. Mitochondrial respiration is a vital source for both. The delicate redox processes that make up respiration are affected by the plant's changing environment. Therefore, mitochondrial regulation is critically important to maintain cellular homeostasis. This involves sensing signals from changes in mitochondrial physiology, transducing this information, and mounting tailored responses, by either adjusting mitochondrial and cellular functions directly or reprogramming gene expression. RECENT ADVANCES Retrograde (RTG) signaling, by which mitochondrial signals control nuclear gene expression, has been a field of very active research in recent years. Nevertheless, no mitochondrial RTG-signaling pathway is yet understood in plants. This review summarizes recent advances toward elucidating redox processes and other bioenergetic factors as a part of RTG signaling of plant mitochondria. CRITICAL ISSUES Novel insights into mitochondrial physiology and redox-regulation provide a framework of upstream signaling. On the other end, downstream responses to modified mitochondrial function have become available, including transcriptomic data and mitochondrial phenotypes, revealing processes in the plant that are under mitochondrial control. FUTURE DIRECTIONS Drawing parallels to chloroplast signaling and mitochondrial signaling in animal systems allows to bridge gaps in the current understanding and to deduce promising directions for future research. It is proposed that targeted usage of new technical approaches, such as quantitative in vivo imaging, will provide novel leverage to the dissection of plant mitochondrial signaling.
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147
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OPA1 promotes pH flashes that spread between contiguous mitochondria without matrix protein exchange. EMBO J 2013; 32:1927-40. [PMID: 23714779 PMCID: PMC3981180 DOI: 10.1038/emboj.2013.124] [Citation(s) in RCA: 82] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2012] [Accepted: 04/19/2013] [Indexed: 01/13/2023] Open
Abstract
The chemical nature and functional significance of mitochondrial flashes associated with fluctuations in mitochondrial membrane potential is unclear. Using a ratiometric pH probe insensitive to superoxide, we show that flashes reflect matrix alkalinization transients of ∼0.4 pH units that persist in cells permeabilized in ion-free solutions and can be evoked by imposed mitochondrial depolarization. Ablation of the pro-fusion protein Optic atrophy 1 specifically abrogated pH flashes and reduced the propagation of matrix photoactivated GFP (paGFP). Ablation or invalidation of the pro-fission Dynamin-related protein 1 greatly enhanced flash propagation between contiguous mitochondria but marginally increased paGFP matrix diffusion, indicating that flashes propagate without matrix content exchange. The pH flashes were associated with synchronous depolarization and hyperpolarization events that promoted the membrane potential equilibration of juxtaposed mitochondria. We propose that flashes are energy conservation events triggered by the opening of a fusion pore between two contiguous mitochondria of different membrane potentials, propagating without matrix fusion to equilibrate the energetic state of connected mitochondria. Mitochondrial fusion events and transient changes in matrix pH linked to membrane depolarization are found to underlie mitochondrial flashes, whose propagation may help equilibrate energy states between connected mitochondria.
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148
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149
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Wei-LaPierre L, Gong G, Gerstner BJ, Ducreux S, Yule DI, Pouvreau S, Wang X, Sheu SS, Cheng H, Dirksen RT, Wang W. Respective contribution of mitochondrial superoxide and pH to mitochondria-targeted circularly permuted yellow fluorescent protein (mt-cpYFP) flash activity. J Biol Chem 2013; 288:10567-77. [PMID: 23457298 DOI: 10.1074/jbc.m113.455709] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Superoxide flashes are transient bursts of superoxide production within the mitochondrial matrix that are detected using the superoxide-sensitive biosensor, mitochondria-targeted circularly permuted YFP (mt-cpYFP). However, due to the pH sensitivity of mt-cpYFP, flashes were suggested to reflect transient events of mitochondrial alkalinization. Here, we simultaneously monitored flashes with mt-cpYFP and mitochondrial pH with carboxy-SNARF-1. In intact cardiac myocytes and purified skeletal muscle mitochondria, robust mt-cpYFP flashes were accompanied by only a modest increase in SNARF-1 ratio (corresponding to a pH increase of <0.1), indicating that matrix alkalinization is minimal during an mt-cpYFP flash. Individual flashes were also accompanied by stepwise increases of MitoSOX signal and decreases of NADH autofluorescence, supporting the superoxide origin of mt-cpYFP flashes. Transient matrix alkalinization induced by NH4Cl only minimally influenced flash frequency and failed to alter flash amplitude. However, matrix acidification modulated superoxide flash frequency in a bimodal manner. Low concentrations of nigericin (< 100 nM) that resulted in a mild dissipation of the mitochondrial pH gradient increased flash frequency, whereas a maximal concentration of nigericin (5 μm) collapsed the pH gradient and abolished flash activity. These results indicate that mt-cpYFP flash events reflect a burst in electron transport chain-dependent superoxide production that is coincident with a modest increase in matrix pH. Furthermore, flash activity depends strongly on a combination of mitochondrial oxidation and pH gradient.
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Affiliation(s)
- Lan Wei-LaPierre
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, New York 14642, USA
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150
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Extramitochondrial domain rich in carbonic anhydrase activity improves myocardial energetics. Proc Natl Acad Sci U S A 2013; 110:E958-67. [PMID: 23431149 DOI: 10.1073/pnas.1213471110] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
CO2 is produced abundantly by cardiac mitochondria. Thus an efficient means for its venting is required to support metabolism. Carbonic anhydrase (CA) enzymes, expressed at various sites in ventricular myocytes, may affect mitochondrial CO2 clearance by catalyzing CO2 hydration (to H(+) and HCO3(-)), thereby changing the gradient for CO2 venting. Using fluorescent dyes to measure changes in pH arising from the intracellular hydration of extracellularly supplied CO2, overall CA activity in the cytoplasm of isolated ventricular myocytes was found to be modest (2.7-fold above spontaneous kinetics). Experiments on ventricular mitochondria demonstrated negligible intramitochondrial CA activity. CA activity was also investigated in intact hearts by (13)C magnetic resonance spectroscopy from the rate of H(13)CO3(-) production from (13)CO2 released specifically from mitochondria by pyruvate dehydrogenase-mediated metabolism of hyperpolarized [1-(13)C]pyruvate. CA activity measured upon [1-(13)C]pyruvate infusion was fourfold higher than the cytoplasm-averaged value. A fluorescent CA ligand colocalized with a mitochondrial marker, indicating that mitochondria are near a CA-rich domain. Based on immunoreactivity, this domain comprises the nominally cytoplasmic CA isoform CAII and sarcoplasmic reticulum-associated CAXIV. Inhibition of extramitochondrial CA activity acidified the matrix (as determined by fluorescence measurements in permeabilized myocytes and isolated mitochondria), impaired cardiac energetics (indexed by the phosphocreatine-to-ATP ratio measured by (31)P magnetic resonance spectroscopy of perfused hearts), and reduced contractility (as measured from the pressure developed in perfused hearts). These data provide evidence for a functional domain of high CA activity around mitochondria to support CO2 venting, particularly during elevated and fluctuating respiratory activity. Aberrant distribution of CA activity therefore may reduce the heart's energetic efficiency.
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