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Rose CR, Verkhratsky A. Sodium homeostasis and signalling: The core and the hub of astrocyte function. Cell Calcium 2024; 117:102817. [PMID: 37979342 DOI: 10.1016/j.ceca.2023.102817] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Accepted: 10/20/2023] [Indexed: 11/20/2023]
Abstract
Neuronal activity and neurochemical stimulation trigger spatio-temporal changes in the cytoplasmic concentration of Na+ ions in astrocytes. These changes constitute the substrate for Na+ signalling and are fundamental for astrocytic excitability. Astrocytic Na+ signals are generated by Na+ influx through neurotransmitter transporters, with primary contribution of glutamate transporters, and through cationic channels; whereas recovery from Na+ transients is mediated mainly by the plasmalemmal Na+/K+ ATPase. Astrocytic Na+ signals regulate the activity of plasmalemmal transporters critical for homeostatic function of astrocytes, thus providing real-time coordination between neuronal activity and astrocytic support.
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Affiliation(s)
- Christine R Rose
- Institute of Neurobiology, Faculty of Mathematics and Natural Sciences, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany.
| | - Alexej Verkhratsky
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, M13 9PT, United Kingdom; Achucarro Centre for Neuroscience, IKERBASQUE, Basque Foundation for Science, 48011 Bilbao, Spain; Department of Forensic Analytical Toxicology, School of Forensic Medicine, China Medical University, Shenyang, China; International Collaborative Center on Big Science Plan for Purinergic Signaling, Chengdu University of Traditional Chinese Medicine, Chengdu, China; Department of Stem Cell Biology, State Research Institute Centre for Innovative Medicine, LT-01102, Vilnius, Lithuania.
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2
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Cabral-Costa JV, Vicente-Gutiérrez C, Agulla J, Lapresa R, Elrod JW, Almeida Á, Bolaños JP, Kowaltowski AJ. Mitochondrial sodium/calcium exchanger NCLX regulates glycolysis in astrocytes, impacting on cognitive performance. J Neurochem 2023; 165:521-535. [PMID: 36563047 PMCID: PMC10478152 DOI: 10.1111/jnc.15745] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Revised: 12/11/2022] [Accepted: 12/12/2022] [Indexed: 12/24/2022]
Abstract
Intracellular Ca2+ concentrations are strictly controlled by plasma membrane transporters, the endoplasmic reticulum, and mitochondria, in which Ca2+ uptake is mediated by the mitochondrial calcium uniporter complex (MCUc), while efflux occurs mainly through the mitochondrial Na+ /Ca2+ exchanger (NCLX). RNAseq database repository searches led us to identify the Nclx transcript as highly enriched in astrocytes when compared with neurons. To assess the role of NCLX in mouse primary culture astrocytes, we inhibited its function both pharmacologically or genetically. This resulted in re-shaping of cytosolic Ca2+ signaling and a metabolic shift that increased glycolytic flux and lactate secretion in a Ca2+ -dependent manner. Interestingly, in vivo genetic deletion of NCLX in hippocampal astrocytes improved cognitive performance in behavioral tasks, whereas hippocampal neuron-specific deletion of NCLX impaired cognitive performance. These results unveil a role for NCLX as a novel modulator of astrocytic glucose metabolism, impacting on cognition.
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Affiliation(s)
- João Victor Cabral-Costa
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil
- Institute of Functional Biology and Genomics, University of Salamanca-CSIC, Salamanca, Spain
| | - Carlos Vicente-Gutiérrez
- Institute of Functional Biology and Genomics, University of Salamanca-CSIC, Salamanca, Spain
- Centro de Investigación Biomédica en Red Sobre Fragilidad y Envejecimiento Saludable (CIBERFES), Instituto de Salud Carlos III, Madrid, Spain
- Institute of Biomedical Research of Salamanca, University Hospital of Salamanca, University of Salamanca-CSIC, Salamanca, Spain
| | - Jesús Agulla
- Institute of Functional Biology and Genomics, University of Salamanca-CSIC, Salamanca, Spain
- Institute of Biomedical Research of Salamanca, University Hospital of Salamanca, University of Salamanca-CSIC, Salamanca, Spain
| | - Rebeca Lapresa
- Institute of Functional Biology and Genomics, University of Salamanca-CSIC, Salamanca, Spain
- Institute of Biomedical Research of Salamanca, University Hospital of Salamanca, University of Salamanca-CSIC, Salamanca, Spain
| | - John W. Elrod
- Center for Translational Medicine, Lewis Katz School of Medicine at Temple University, Philadelphia, Pennsylvania, USA
| | - Ángeles Almeida
- Institute of Functional Biology and Genomics, University of Salamanca-CSIC, Salamanca, Spain
- Institute of Biomedical Research of Salamanca, University Hospital of Salamanca, University of Salamanca-CSIC, Salamanca, Spain
| | - Juan P. Bolaños
- Institute of Functional Biology and Genomics, University of Salamanca-CSIC, Salamanca, Spain
- Centro de Investigación Biomédica en Red Sobre Fragilidad y Envejecimiento Saludable (CIBERFES), Instituto de Salud Carlos III, Madrid, Spain
- Institute of Biomedical Research of Salamanca, University Hospital of Salamanca, University of Salamanca-CSIC, Salamanca, Spain
| | - Alicia J. Kowaltowski
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil
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3
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Mitochondrial Ca2+ handling as a cell signaling hub: lessons from astrocyte function. Essays Biochem 2023; 67:63-75. [PMID: 36636961 DOI: 10.1042/ebc20220094] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Revised: 12/16/2022] [Accepted: 12/22/2022] [Indexed: 01/14/2023]
Abstract
Astrocytes are a heterogenous population of macroglial cells spread throughout the central nervous system with diverse functions, expression signatures, and intricate morphologies. Their subcellular compartments contain a distinct range of mitochondria, with functional microdomains exhibiting widespread activities, such as controlling local metabolism and Ca2+ signaling. Ca2+ is an ion of utmost importance, both physiologically and pathologically, and participates in critical central nervous system processes, including synaptic plasticity, neuron-astrocyte integration, excitotoxicity, and mitochondrial physiology and metabolism. The mitochondrial Ca2+ handling system is formed by the mitochondrial Ca2+ uniporter complex (MCUc), which mediates Ca2+ influx, and the mitochondrial Na+/Ca2+ exchanger (NCLX), responsible for most mitochondrial Ca2+ efflux, as well as additional components, including the mitochondrial permeability transition pore (mtPTP). Over the last decades, mitochondrial Ca2+ handling has been shown to be key for brain homeostasis, acting centrally in physiopathological processes such as astrogliosis, astrocyte-neuron activity integration, energy metabolism control, and neurodegeneration. In this review, we discuss the current state of knowledge regarding the mitochondrial Ca2+ handling system molecular composition, highlighting its impact on astrocytic homeostasis.
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4
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Khmelinskii I, Makarov V. Reversible and irreversible mitochondrial swelling in vitro. Biophys Chem 2021; 278:106668. [PMID: 34418677 DOI: 10.1016/j.bpc.2021.106668] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 08/07/2021] [Accepted: 08/10/2021] [Indexed: 11/18/2022]
Abstract
Mitochondrial activity as regards ATP production strongly depends on mitochondrial swelling (MS) mode. Therefore, this work analyzes reversible and irreversible MS using a detailed biophysical model. The reported model includes mechanical properties of the inner mitochondrial membrane (IMM). The model describes MS dynamics for spherically symmetric, axisymmetric ellipsoidal and general ellipsoidal mitochondria. Mechanical stretching properties of the IMM were described by a second-rank rigidity tensor. The tensor components were estimated by fitting to the earlier reported results of in vitro experiments. The IMM rigidity constant of ca. 0.008 dyn/nm was obtained for linear deformations. The model also included membrane bending effects, which were small compared to those of membrane stretching. The model was also tested by simulation of the earlier reported experimental data and of the system dynamics at different initial conditions, predicting the system behavior. The transition criteria from reversible to irreversible swelling were determined and tested. The presently developed model is applicable directly to the analysis of in vitro experimental data, while additional improvements are necessary before it could be used to describe mitochondrial swelling in vivo. The reported theoretical model also provides an idea of physically consistent mechanism for the permeability transport pore (PTP) opening, which depends on the IMM stretching stress. In the current study, this idea is discussed briefly, but a detailed theoretical analysis of these ideas will be performed later. The currently developed model provides new understanding of the detailed MS mechanism and of the conditions for the transition between reversible and irreversible MS modes. On the other hand, the current model provides useful mathematical tools, that may be successfully used in mitochondrial biophysics research, and also in other applications, predicting the behavior of mitochondria in different conditions of the surrounding media in vitro or cellular cyto(sarco)plasm in vivo. These mathematical tools are based on real biophysical processes occurring in mitochondria. Thus, we note a significant progress in the theoretical approach, which may be used in real biological systems, compared to the earlier reported models. Significance of this study derives from inclusion of IMM mechanical properties, which directly impact the reversible and irreversible mitochondrial swelling dynamics. Reversible swelling corresponds to reversible IMM deformations, while irreversible swelling corresponds to irreversible deformations, with eventual membrane disruption. The IMM mechanical properties are directly dependent on the membrane biochemical composition and structure. The IMM deformationas are induced by osmotic pressure created by the ionic/neutral solute imbalance between the mitochondrial matrix media and the bulk solution in vitro, or cyto(sarco)plasm in vivo. The novelty of the reported model is in the biophysical mechanism detailing ionic and neutral solute transport for a large number of solutes, which were not taken into account in the earlier reported biophysical models of MS. Therefore, the reported model allows understanding response of mitochondria to the changes of initial concentration(s) of any of the solute(s) included in the model. Note that the values of all of the model parameters and kinetic constants have been estimated and the resulting complete model may be used for quantitative analysis of mitochondrial swelling dynamics in conditions of real in vitro experiments.
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Affiliation(s)
- Igor Khmelinskii
- Universidade do Algarve, FCT, DQB and CEOT, 8005-139 Faro, Portugal
| | - Vladimir Makarov
- University of Puerto Rico, Rio Piedras Campus, PO Box 23343, San Juan, PR 00931-3343, USA.
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5
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Wang X, An P, Gu Z, Luo Y, Luo J. Mitochondrial Metal Ion Transport in Cell Metabolism and Disease. Int J Mol Sci 2021; 22:ijms22147525. [PMID: 34299144 PMCID: PMC8305404 DOI: 10.3390/ijms22147525] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Revised: 07/06/2021] [Accepted: 07/13/2021] [Indexed: 12/19/2022] Open
Abstract
Mitochondria are vital to life and provide biological energy for other organelles and cell physiological processes. On the mitochondrial double layer membrane, there are a variety of channels and transporters to transport different metal ions, such as Ca2+, K+, Na+, Mg2+, Zn2+ and Fe2+/Fe3+. Emerging evidence in recent years has shown that the metal ion transport is essential for mitochondrial function and cellular metabolism, including oxidative phosphorylation (OXPHOS), ATP production, mitochondrial integrity, mitochondrial volume, enzyme activity, signal transduction, proliferation and apoptosis. The homeostasis of mitochondrial metal ions plays an important role in maintaining mitochondria and cell functions and regulating multiple diseases. In particular, channels and transporters for transporting mitochondrial metal ions are very critical, which can be used as potential targets to treat neurodegeneration, cardiovascular diseases, cancer, diabetes and other metabolic diseases. This review summarizes the current research on several types of mitochondrial metal ion channels/transporters and their functions in cell metabolism and diseases, providing strong evidence and therapeutic strategies for further insights into related diseases.
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Affiliation(s)
- Xuan Wang
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, Key Laboratory of Precision Nutrition and Food Quality, Department of Nutrition and Health, China Agricultural University, Beijing 100193, China; (X.W.); (P.A.)
| | - Peng An
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, Key Laboratory of Precision Nutrition and Food Quality, Department of Nutrition and Health, China Agricultural University, Beijing 100193, China; (X.W.); (P.A.)
| | - Zhenglong Gu
- Division of Nutritional Sciences, Cornell University, Ithaca, NY 14853, USA;
| | - Yongting Luo
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, Key Laboratory of Precision Nutrition and Food Quality, Department of Nutrition and Health, China Agricultural University, Beijing 100193, China; (X.W.); (P.A.)
- Correspondence: (Y.L.); (J.L.)
| | - Junjie Luo
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, Key Laboratory of Precision Nutrition and Food Quality, Department of Nutrition and Health, China Agricultural University, Beijing 100193, China; (X.W.); (P.A.)
- Correspondence: (Y.L.); (J.L.)
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6
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Felix L, Delekate A, Petzold GC, Rose CR. Sodium Fluctuations in Astroglia and Their Potential Impact on Astrocyte Function. Front Physiol 2020; 11:871. [PMID: 32903427 PMCID: PMC7435049 DOI: 10.3389/fphys.2020.00871] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Accepted: 06/29/2020] [Indexed: 12/12/2022] Open
Abstract
Astrocytes are the main cell type responsible for the regulation of brain homeostasis, including the maintenance of ion gradients and neurotransmitter clearance. These processes are tightly coupled to changes in the intracellular sodium (Na+) concentration. While activation of the sodium-potassium-ATPase (NKA) in response to an elevation of extracellular K+ may decrease intracellular Na+, the cotransport of transmitters, such as glutamate, together with Na+ results in an increase in astrocytic Na+. This increase in intracellular Na+ can modulate, for instance, metabolic downstream pathways. Thereby, astrocytes are capable to react on a fast time scale to surrounding neuronal activity via intracellular Na+ fluctuations and adjust energy production to the demand of their environment. Beside the well-documented conventional roles of Na+ signaling mainly mediated through changes in its electrochemical gradient, several recent studies have identified more atypical roles for Na+, including protein interactions leading to changes in their biochemical activity or Na+-dependent regulation of gene expression. In this review, we will address both the conventional as well as the atypical functions of astrocytic Na+ signaling, presenting the role of transporters and channels involved and their implications for physiological processes in the central nervous system (CNS). We will also discuss how these important functions are affected under pathological conditions, including stroke and migraine. We postulate that Na+ is an essential player not only in the maintenance of homeostatic processes but also as a messenger for the fast communication between neurons and astrocytes, adjusting the functional properties of various cellular interaction partners to the needs of the surrounding network.
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Affiliation(s)
- Lisa Felix
- Institute of Neurobiology, Heinrich Heine University Duesseldorf, Duesseldorf, Germany
| | - Andrea Delekate
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | - Gabor C Petzold
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany.,Division of Vascular Neurology, Department of Neurology, University Hospital Bonn, Bonn, Germany
| | - Christine R Rose
- Institute of Neurobiology, Heinrich Heine University Duesseldorf, Duesseldorf, Germany
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7
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Knockout of PINK1 altered the neural connectivity of Drosophila dopamine PPM3 neurons at input and output sites. INVERTEBRATE NEUROSCIENCE 2020; 20:11. [PMID: 32766952 DOI: 10.1007/s10158-020-00244-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Accepted: 07/09/2020] [Indexed: 12/19/2022]
Abstract
Impairment of the dopamine system is the main cause of Parkinson disease (PD). PTEN-induced kinase 1 (PINK1) is possibly involved in pathogenesis of PD. However, its role in dopaminergic neurons has not been fully established yet. In the present investigation, we have used the PINK1 knockout Drosophila model to explore the role of PINK1 in dopaminergic neurons. Electrophysiological and behavioral tests indicated that PINK1 elimination enhances the neural transmission from the presynaptic part of dopaminergic neurons in the protocerebral posterior medial region 3 (PPM3) to PPM3 neurons (which are homologous to those in the substantia nigra in humans). Firing properties of the action potential in PPM3 neurons were also altered in the PINK1 knockout genotypes. Abnormal motor ability was also observed in these PINK1 knockout animals. Our results indicate that knockout of PINK1 could alter both the input and output properties of PPM3 neurons.
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8
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Mitochondrial Calcium Regulation of Redox Signaling in Cancer. Cells 2020; 9:cells9020432. [PMID: 32059571 PMCID: PMC7072435 DOI: 10.3390/cells9020432] [Citation(s) in RCA: 68] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Revised: 02/05/2020] [Accepted: 02/10/2020] [Indexed: 02/07/2023] Open
Abstract
Calcium (Ca2+) uptake into the mitochondria shapes cellular Ca2+ signals and acts as a key effector for ATP generation. In addition, mitochondria-derived reactive oxygen species (mROS), produced as a consequence of ATP synthesis at the electron transport chain (ETC), modulate cellular signaling pathways that contribute to many cellular processes. Cancer cells modulate mitochondrial Ca2+ ([Ca2+]m) homeostasis by altering the expression and function of mitochondrial Ca2+ channels and transporters required for the uptake and extrusion of mitochondrial Ca2+. Regulated elevations in [Ca2+]m are required for the activity of several mitochondrial enzymes, and this in turn regulates metabolic flux, mitochondrial ETC function and mROS generation. Alterations in both [Ca2+]m and mROS are hallmarks of many tumors, and elevated mROS is a known driver of pro-tumorigenic redox signaling, resulting in the activation of pathways implicated in cellular proliferation, metabolic alterations and stress-adaptations. In this review, we highlight recent studies that demonstrate the interplay between [Ca2+]m and mROS signaling in cancer.
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9
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Multipurpose Na + ions mediate excitation and cellular homeostasis: Evolution of the concept of Na + pumps and Na +/Ca 2+ exchangers. Cell Calcium 2020; 87:102166. [PMID: 32006802 DOI: 10.1016/j.ceca.2020.102166] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Accepted: 01/21/2020] [Indexed: 12/14/2022]
Abstract
Ionic signalling is the most ancient form of regulation of cellular functions in response to environmental challenges. Signals, mediated by Na+ fluxes and spatio-temporal fluctuations of Na+ concentration in cellular organelles and cellular compartments contribute to the most fundamental cellular processes such as membrane excitability and energy production. At the very core of ionic signalling lies the Na+-K+ ATP-driven pump (or NKA) which creates trans-plasmalemmal ion gradients that sustain ionic fluxes through ion channels and numerous Na+-dependent transporters that maintain cellular and tissue homeostasis. Here we present a brief account of the history of research into NKA, Na+ -dependent transporters and Na+ signalling.
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10
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Meyer J, Untiet V, Fahlke C, Gensch T, Rose CR. Quantitative determination of cellular [Na +] by fluorescence lifetime imaging with CoroNaGreen. J Gen Physiol 2019; 151:1319-1331. [PMID: 31597684 PMCID: PMC6829561 DOI: 10.1085/jgp.201912404] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Accepted: 09/11/2019] [Indexed: 12/23/2022] Open
Abstract
Meyer et al. establish the suitability of the sodium-sensitive indicator dye CoroNaGreen for fluorescence lifetime imaging inside cells. This approach represents a valuable tool for quantitative and dynamic determination of intracellular sodium concentrations independent of dye concentration. Fluorescence lifetime imaging microscopy (FLIM) with fluorescent ion sensors enables the measurement of ion concentrations based on the detection of photon emission events after brief excitation with a pulsed laser source. In contrast to intensity-based imaging, it is independent of dye concentration, photobleaching, or focus drift and has thus been successfully employed for quantitative analysis of, e.g., calcium levels in different cell types and cellular microdomains. Here, we tested the suitability of CoroNaGreen for FLIM-based determination of sodium concentration ([Na+]) inside cells. In vitro measurements confirmed that fluorescence lifetimes of CoroNaGreen (CoroNaFL) increased with increasing [Na+]. Moreover, CoroNaFL was largely independent of changes in potassium concentration or viscosity. Changes in pH slightly affected FL in the acidic range (pH ≤ 5.5). For intracellular determination of [Na+], HEK293T cells were loaded with the membrane-permeable form of CoroNaGreen. Fluorescence decay curves of CoroNaGreen, derived from time-correlated single-photon counting, were approximated by a bi-exponential decay. In situ calibrations revealed a sigmoidal dependence of CoroNaFL on [Na+] between 0 and 150 mM, exhibiting an apparent Kd of ∼80 mM. Based on these calibrations, a [Na+] of 17.6 mM was determined in the cytosol. Cellular nuclei showed a significantly lower [Na+] of 13.0 mM, whereas [Na+] in perinuclear regions was significantly higher (26.5 mM). Metabolic inhibition or blocking the Na+/K+-ATPase by removal of extracellular K+ caused significant [Na+] increases in all cellular subcompartments. Using an alternative approach for data analysis (“Ratio FLIM”) increased the temporal resolution and revealed a sequential response to K+ removal, with cytosolic [Na+] increasing first, followed by the nucleus and finally the perinuclear regions. Taken together, our results show that CoroNaGreen is suitable for dynamic, FLIM-based determination of intracellular [Na+]. This approach thus represents a valuable tool for quantitative determination of [Na+] and changes thereof in different subcellular compartments.
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Affiliation(s)
- Jan Meyer
- Institute of Neurobiology, Faculty of Mathematics and Natural Sciences, Heinrich Heine University Düsseldorf, Düsseldorf, Germany.,Institute of Complex Systems 4 (ICS-4), Zelluläre Biophysik, Forschungszentrum Jülich, Jülich, Germany
| | - Verena Untiet
- Institute of Complex Systems 4 (ICS-4), Zelluläre Biophysik, Forschungszentrum Jülich, Jülich, Germany
| | - Christoph Fahlke
- Institute of Complex Systems 4 (ICS-4), Zelluläre Biophysik, Forschungszentrum Jülich, Jülich, Germany
| | - Thomas Gensch
- Institute of Complex Systems 4 (ICS-4), Zelluläre Biophysik, Forschungszentrum Jülich, Jülich, Germany
| | - Christine R Rose
- Institute of Neurobiology, Faculty of Mathematics and Natural Sciences, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
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11
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Kelly AC, Smith KE, Purvis WG, Min CG, Weber CS, Cooksey AM, Hasilo C, Paraskevas S, Suszynski TM, Weegman BP, Anderson MJ, Camacho LE, Harland RC, Loudovaris T, Jandova J, Molano DS, Price ND, Georgiev IG, Scott WE, Manas D, Shaw J, O’Gorman D, Kin T, McCarthy FM, Szot GL, Posselt AM, Stock PG, Karatzas T, Shapiro WJ, Lynch RM, Limesand SW, Papas KK. Oxygen Perfusion (Persufflation) of Human Pancreata Enhances Insulin Secretion and Attenuates Islet Proinflammatory Signaling. Transplantation 2019; 103:160-167. [PMID: 30095738 PMCID: PMC6371803 DOI: 10.1097/tp.0000000000002400] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
BACKGROUND All human islets used in research and for the clinical treatment of diabetes are subject to ischemic damage during pancreas procurement, preservation, and islet isolation. A major factor influencing islet function is exposure of pancreata to cold ischemia during unavoidable windows of preservation by static cold storage (SCS). Improved preservation methods may prevent this functional deterioration. In the present study, we investigated whether pancreas preservation by gaseous oxygen perfusion (persufflation) better preserved islet function versus SCS. METHODS Human pancreata were preserved by SCS or by persufflation in combination with SCS. Islets were subsequently isolated, and preparations in each group matched for SCS or total preservation time were compared using dynamic glucose-stimulated insulin secretion as a measure of β-cell function and RNA sequencing to elucidate transcriptomic changes. RESULTS Persufflated pancreata had reduced SCS time, which resulted in islets with higher glucose-stimulated insulin secretion compared to islets from SCS only pancreata. RNA sequencing of islets from persufflated pancreata identified reduced inflammatory and greater metabolic gene expression, consistent with expectations of reducing cold ischemic exposure. Portions of these transcriptional responses were not associated with time spent in SCS and were attributable to pancreatic reoxygenation. Furthermore, persufflation extended the total preservation time by 50% without any detectable decline in islet function or viability. CONCLUSIONS These data demonstrate that pancreas preservation by persufflation rather than SCS before islet isolation reduces inflammatory responses and promotes metabolic pathways in human islets, which results in improved β cell function.
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Affiliation(s)
- Amy C. Kelly
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson AZ
| | - Kate E. Smith
- Physiological Sciences, University of Arizona, Tucson AZ
| | - William G. Purvis
- Department of Surgery, Institute for Cellular Transplantation, University of Arizona, Tucson AZ
| | | | - Craig S. Weber
- Physiological Sciences, University of Arizona, Tucson AZ
| | - Amanda M. Cooksey
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson AZ
| | - Craig Hasilo
- Human Islet Transplant Laboratory, McGill University Health Centre, Montreal, Quebec, CA
| | - Steven Paraskevas
- Human Islet Transplant Laboratory, McGill University Health Centre, Montreal, Quebec, CA
| | - Thomas M. Suszynski
- Department of Surgery, Institute for Cellular Transplantation, University of Arizona, Tucson AZ
| | - Bradley P. Weegman
- Department of Surgery, Institute for Cellular Transplantation, University of Arizona, Tucson AZ
| | - Miranda J. Anderson
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson AZ
| | - Leticia E. Camacho
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson AZ
| | - Robert C. Harland
- Department of Surgery, Institute for Cellular Transplantation, University of Arizona, Tucson AZ
| | - Tom Loudovaris
- Department of Surgery, Institute for Cellular Transplantation, University of Arizona, Tucson AZ
| | - Jana Jandova
- Department of Surgery, Institute for Cellular Transplantation, University of Arizona, Tucson AZ
| | - Diana S. Molano
- Department of Surgery, Institute for Cellular Transplantation, University of Arizona, Tucson AZ
| | - Nicholas D. Price
- Department of Surgery, Institute for Cellular Transplantation, University of Arizona, Tucson AZ
| | - Ivan G. Georgiev
- Department of Surgery, Institute for Cellular Transplantation, University of Arizona, Tucson AZ
| | - William E. Scott
- Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, UK
| | - Derek Manas
- Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, UK
| | - James Shaw
- Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, UK
| | - Doug O’Gorman
- Clinical Islet Transplant Program, Alberta Diabetes Institute, University of Alberta, Edmonton, Alberta, CA
| | - Tatsuya Kin
- Clinical Islet Transplant Program, Alberta Diabetes Institute, University of Alberta, Edmonton, Alberta, CA
| | - Fiona M. McCarthy
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson AZ
| | - Gregory L. Szot
- Department of Surgery, University of California San Francisco, San Francisco, CA
| | - Andrew M. Posselt
- Department of Surgery, University of California San Francisco, San Francisco, CA
| | - Peter G. Stock
- Department of Surgery, University of California San Francisco, San Francisco, CA
| | | | - William J. Shapiro
- Clinical Islet Transplant Program, Alberta Diabetes Institute, University of Alberta, Edmonton, Alberta, CA
| | | | - Sean W. Limesand
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson AZ
| | - Klearchos K. Papas
- Department of Surgery, Institute for Cellular Transplantation, University of Arizona, Tucson AZ
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12
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Abstract
Mitochondrial Ca2+ regulation is crucial for bioenergetics and cellular signaling. The mechanisms controlling mitochondrial calcium homeostasis have been recently unraveled with the discovery of mitochondrial inner membrane proteins that regulate mitochondrial Ca2+ uptake and extrusion. Mitochondrial Ca2+ uptake depends on a large complex of proteins centered around the Ca2+ channel protein, mitochondrial Ca2+ uniporter (MCU) in close interactions with several regulatory subunits (MCUb, EMRE, MICU1, MICU2). Mitochondrial Ca2+ extrusion is mainly mediated by the mitochondrial Na+/Ca2+/Li+ exchanger (NCLX). Here, we review the major players of mitochondrial Ca2+ homeostasis and their physiological functions.
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Affiliation(s)
- Trayambak Pathak
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, PA, United States
| | - Mohamed Trebak
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, PA, United States.
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13
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Smith CO, Wang YT, Nadtochiy SM, Miller JH, Jonas EA, Dirksen RT, Nehrke K, Brookes PS. Cardiac metabolic effects of K Na1.2 channel deletion and evidence for its mitochondrial localization. FASEB J 2018; 32:fj201800139R. [PMID: 29863912 PMCID: PMC6181635 DOI: 10.1096/fj.201800139r] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Accepted: 05/07/2018] [Indexed: 12/18/2022]
Abstract
Controversy surrounds the molecular identity of mitochondrial K+ channels that are important for protection against cardiac ischemia-reperfusion injury. Although KNa1.2 (sodium-activated potassium channel encoded by Kcn2) is necessary for cardioprotection by volatile anesthetics, electrophysiological evidence for a channel of this type in mitochondria is lacking. The endogenous physiological role of a potential mito-KNa1.2 channel is also unclear. In this study, single channel patch-clamp of 27 independent cardiac mitochondrial inner membrane (mitoplast) preparations from wild-type (WT) mice yielded 6 channels matching the known ion sensitivity, ion selectivity, pharmacology, and conductance properties of KNa1.2 (slope conductance, 138 ± 1 pS). However, similar experiments on 40 preparations from Kcnt2-/- mice yielded no such channels. The KNa opener bithionol uncoupled respiration in WT but not Kcnt2-/- cardiomyocytes. Furthermore, when oxidizing only fat as substrate, Kcnt2-/- cardiomyocytes and hearts were less responsive to increases in energetic demand. Kcnt2-/- mice also had elevated body fat, but no baseline differences in the cardiac metabolome. These data support the existence of a cardiac mitochondrial KNa1.2 channel, and a role for cardiac KNa1.2 in regulating metabolism under conditions of high energetic demand.-Smith, C. O., Wang, Y. T., Nadtochiy, S. M., Miller, J. H., Jonas, E. A., Dirksen, R. T., Nehrke, K., Brookes, P. S. Cardiac metabolic effects of KNa1.2 channel deletion and evidence for its mitochondrial localization.
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Affiliation(s)
- Charles O. Smith
- Department of Biochemistry, University of Rochester Medical Center, Rochester, New York, USA
| | - Yves T. Wang
- Department of Anesthesiology and Perioperative Medicine, University of Rochester Medical Center, Rochester, New York, USA
| | - Sergiy M. Nadtochiy
- Department of Anesthesiology and Perioperative Medicine, University of Rochester Medical Center, Rochester, New York, USA
| | - James H. Miller
- Department of Anesthesiology and Perioperative Medicine, University of Rochester Medical Center, Rochester, New York, USA
| | - Elizabeth A. Jonas
- Section of Endocrinology, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Robert T. Dirksen
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, New York, USA
| | - Keith Nehrke
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, New York, USA
- Department of Medicine, University of Rochester Medical Center, Rochester, New York, USA
| | - Paul S. Brookes
- Department of Anesthesiology and Perioperative Medicine, University of Rochester Medical Center, Rochester, New York, USA
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, New York, USA
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14
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Function, regulation and physiological role of the mitochondrial Na + /Ca 2+ exchanger, NCLX. CURRENT OPINION IN PHYSIOLOGY 2018. [DOI: 10.1016/j.cophys.2018.02.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
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15
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Arduino DM, Perocchi F. Pharmacological modulation of mitochondrial calcium homeostasis. J Physiol 2018; 596:2717-2733. [PMID: 29319185 DOI: 10.1113/jp274959] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Accepted: 12/13/2017] [Indexed: 12/26/2022] Open
Abstract
Mitochondria are pivotal organelles in calcium (Ca2+ ) handling and signalling, constituting intracellular checkpoints for numerous processes that are vital for cell life. Alterations in mitochondrial Ca2+ homeostasis have been linked to a variety of pathological conditions and are critical in the aetiology of several human diseases. Efforts have been taken to harness mitochondrial Ca2+ transport mechanisms for therapeutic intervention, but pharmacological compounds that direct and selectively modulate mitochondrial Ca2+ homeostasis are currently lacking. New avenues have, however, emerged with the breakthrough discoveries on the genetic identification of the main players involved in mitochondrial Ca2+ influx and efflux pathways and with recent hints towards a deep understanding of the function of these molecular systems. Here, we review the current advances in the understanding of the mechanisms and regulation of mitochondrial Ca2+ homeostasis and its contribution to physiology and human disease. We also introduce and comment on the recent progress towards a systems-level pharmacological targeting of mitochondrial Ca2+ homeostasis.
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Affiliation(s)
- Daniela M Arduino
- Gene Center, Department of Biochemistry, Ludwig-Maximilians Universität München, Munich, 81377, Germany.,Institute for Diabetes and Obesity, Helmholtz Diabetes Center (HDC), Helmholtz Zentrum München and German National Diabetes Center (DZD), Neuherberg, 85764, Germany
| | - Fabiana Perocchi
- Gene Center, Department of Biochemistry, Ludwig-Maximilians Universität München, Munich, 81377, Germany.,Institute for Diabetes and Obesity, Helmholtz Diabetes Center (HDC), Helmholtz Zentrum München and German National Diabetes Center (DZD), Neuherberg, 85764, Germany
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16
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Coupling between the TRPC3 ion channel and the NCX1 transporter contributed to VEGF-induced ERK1/2 activation and angiogenesis in human primary endothelial cells. Cell Signal 2017; 37:12-30. [DOI: 10.1016/j.cellsig.2017.05.013] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Revised: 05/05/2017] [Accepted: 05/18/2017] [Indexed: 12/15/2022]
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17
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18
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Ben-Kasus Nissim T, Zhang X, Elazar A, Roy S, Stolwijk JA, Zhou Y, Motiani RK, Gueguinou M, Hempel N, Hershfinkel M, Gill DL, Trebak M, Sekler I. Mitochondria control store-operated Ca 2+ entry through Na + and redox signals. EMBO J 2017; 36:797-815. [PMID: 28219928 DOI: 10.15252/embj.201592481] [Citation(s) in RCA: 77] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Revised: 12/25/2016] [Accepted: 01/05/2017] [Indexed: 02/05/2023] Open
Abstract
Mitochondria exert important control over plasma membrane (PM) Orai1 channels mediating store-operated Ca2+ entry (SOCE). Although the sensing of endoplasmic reticulum (ER) Ca2+ stores by STIM proteins and coupling to Orai1 channels is well understood, how mitochondria communicate with Orai1 channels to regulate SOCE activation remains elusive. Here, we reveal that SOCE is accompanied by a rise in cytosolic Na+ that is critical in activating the mitochondrial Na+/Ca2+ exchanger (NCLX) causing enhanced mitochondrial Na+ uptake and Ca2+ efflux. Omission of extracellular Na+ prevents the cytosolic Na+ rise, inhibits NCLX activity, and impairs SOCE and Orai1 channel current. We show further that SOCE activates a mitochondrial redox transient which is dependent on NCLX and is required for preventing Orai1 inactivation through oxidation of a critical cysteine (Cys195) in the third transmembrane helix of Orai1. We show that mitochondrial targeting of catalase is sufficient to rescue redox transients, SOCE, and Orai1 currents in NCLX-deficient cells. Our findings identify a hitherto unknown NCLX-mediated pathway that coordinates Na+ and Ca2+ signals to effect mitochondrial redox control over SOCE.
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Affiliation(s)
- Tsipi Ben-Kasus Nissim
- The Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Xuexin Zhang
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, PA, USA
| | - Assaf Elazar
- The Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Soumitra Roy
- The Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Judith A Stolwijk
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, PA, USA
| | - Yandong Zhou
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, PA, USA
| | - Rajender K Motiani
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, PA, USA
| | - Maxime Gueguinou
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, PA, USA
| | - Nadine Hempel
- Department of Pharmacology, The Pennsylvania State University College of Medicine, Hershey, PA, USA
| | - Michal Hershfinkel
- The Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Donald L Gill
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, PA, USA
| | - Mohamed Trebak
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, PA, USA
| | - Israel Sekler
- The Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
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19
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Mitochondrial Calcium Handling in Physiology and Disease. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 982:25-47. [PMID: 28551780 DOI: 10.1007/978-3-319-55330-6_2] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Calcium (Ca2+) accumulation inside mitochondria represents a pleiotropic signal controlling a wide range of cellular functions, including key metabolic pathways and life/death decisions. This phenomenon has been first described in the 1960s, but the identity of the molecules controlling this process remained a mystery until just few years ago, when both mitochondrial Ca2+ uptake and release systems were genetically dissected. This finally opened the possibility to develop genetic models to directly test the contribution of mitochondrial Ca2+ homeostasis to cellular functions. Here we summarize our current understanding of the molecular machinery that controls mitochondrial Ca2+ handling and critically evaluate the physiopathological role of mitochondrial Ca2+ signaling, based on recent evidences obtained through in vitro and in vivo models.
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20
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Blaustein MP, Chen L, Hamlyn JM, Leenen FHH, Lingrel JB, Wier WG, Zhang J. Pivotal role of α2 Na + pumps and their high affinity ouabain binding site in cardiovascular health and disease. J Physiol 2016; 594:6079-6103. [PMID: 27350568 DOI: 10.1113/jp272419] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Accepted: 06/18/2016] [Indexed: 12/13/2022] Open
Abstract
Reduced smooth muscle (SM)-specific α2 Na+ pump expression elevates basal blood pressure (BP) and increases BP sensitivity to angiotensin II (Ang II) and dietary NaCl, whilst SM-α2 overexpression lowers basal BP and decreases Ang II/salt sensitivity. Prolonged ouabain infusion induces hypertension in rodents, and ouabain-resistant mutation of the α2 ouabain binding site (α2R/R mice) confers resistance to several forms of hypertension. Pressure overload-induced heart hypertrophy and failure are attenuated in cardio-specific α2 knockout, cardio-specific α2 overexpression and α2R/R mice. We propose a unifying hypothesis that reconciles these apparently disparate findings: brain mechanisms, activated by Ang II and high NaCl, regulate sympathetic drive and a novel neurohumoral pathway mediated by both brain and circulating endogenous ouabain (EO). Circulating EO modulates ouabain-sensitive α2 Na+ pump activity and Ca2+ transporter expression and, via Na+ /Ca2+ exchange, Ca2+ homeostasis. This regulates sensitivity to sympathetic activity, Ca2+ signalling and arterial and cardiac contraction.
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Affiliation(s)
- Mordecai P Blaustein
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, 21201, USA. .,Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, 21201, USA.
| | - Ling Chen
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, 21201, USA.,Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - John M Hamlyn
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Frans H H Leenen
- Hypertension Unit, University of Ottawa Heart Institute, Ottawa, ON, Canada, K1Y 4W7
| | - Jerry B Lingrel
- Department of Molecular Genetics, Biochemistry and Microbiology, University of Cincinnati College of Medicine, Cincinnati, OH, 45267-0524, USA
| | - W Gil Wier
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Jin Zhang
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
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21
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The Protein Tyrosine Kinase Inhibitor Tyrphostin 23 Strongly Accelerates Glycolytic Lactate Production in Cultured Primary Astrocytes. Neurochem Res 2016; 41:2607-2618. [PMID: 27278759 DOI: 10.1007/s11064-016-1972-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Revised: 05/29/2016] [Accepted: 06/01/2016] [Indexed: 02/07/2023]
Abstract
Tyrphostin 23 (T23) is a well-known inhibitor of protein tyrosine kinases. To investigate potential acute effects of T23 on the viability and the glucose metabolism of brain cells, we exposed cultured primary rat astrocytes to T23 for up to 4 h. While the viability and the morphology of the cultured astrocytes were not acutely affected by the presence of T23 in concentrations of up to 300 µM, this compound caused a rapid, time- and concentration-dependent increase in glucose consumption and lactate release. Maximal effects on glycolytic flux were found for incubations with 100 µM T23 for 2 h which doubled both glucose consumption and lactate production. The stimulation of glycolytic flux by T23 was reversible, completely abolished upon removal of the compound and not found in presence of other known inhibitors of endocytosis. Structurally related compounds such as tyrphostin 25 and catechol or modulators of AMP kinase activity did neither affect the basal nor the T23-stimulated lactate production by astrocytes. In contrast, the presence of the phosphatase inhibitor vanadate completely abolished the stimulation by T23 of astrocytic lactate production in a concentration-dependent manner. These data suggest that T23-sensitive phosphorylation/dephosphorylation events are involved in the regulation of astrocytic glycolysis.
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22
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Abstract
In the last 5 years, most of the molecules that control mitochondrial Ca(2+) homeostasis have been finally identified. Mitochondrial Ca(2+) uptake is mediated by the Mitochondrial Calcium Uniporter (MCU) complex, a macromolecular structure that guarantees Ca(2+) accumulation inside mitochondrial matrix upon increases in cytosolic Ca(2+). Conversely, Ca(2+) release is under the control of the Na(+)/Ca(2+) exchanger, encoded by the NCLX gene, and of a H(+)/Ca(2+) antiporter, whose identity is still debated. The low affinity of the MCU complex, coupled to the activity of the efflux systems, protects cells from continuous futile cycles of Ca(2+) across the inner mitochondrial membrane and consequent massive energy dissipation. In this review, we discuss the basic principles that govern mitochondrial Ca(2+) homeostasis and the methods used to investigate the dynamics of Ca(2+) concentration within the organelles. We discuss the functional and structural role of the different molecules involved in mitochondrial Ca(2+) handling and their pathophysiological role.
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Affiliation(s)
- Diego De Stefani
- Department of Biomedical Sciences, University of Padova, 35121 Padova, Italy; , ,
| | - Rosario Rizzuto
- Department of Biomedical Sciences, University of Padova, 35121 Padova, Italy; , , .,National Research Council (CNR) Neuroscience Institute, 35121 Padova, Italy
| | - Tullio Pozzan
- Department of Biomedical Sciences, University of Padova, 35121 Padova, Italy; , , .,National Research Council (CNR) Neuroscience Institute, 35121 Padova, Italy.,Venetian Institute of Molecular Medicine, 35121 Padova, Italy
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23
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Laskowski M, Augustynek B, Kulawiak B, Koprowski P, Bednarczyk P, Jarmuszkiewicz W, Szewczyk A. What do we not know about mitochondrial potassium channels? BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2016; 1857:1247-1257. [PMID: 26951942 DOI: 10.1016/j.bbabio.2016.03.007] [Citation(s) in RCA: 98] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Revised: 03/02/2016] [Accepted: 03/03/2016] [Indexed: 01/14/2023]
Abstract
In this review, we summarize our knowledge about mitochondrial potassium channels, with a special focus on unanswered questions in this field. The following potassium channels have been well described in the inner mitochondrial membrane: ATP-regulated potassium channel, Ca(2+)-activated potassium channel, the voltage-gated Kv1.3 potassium channel, and the two-pore domain TASK-3 potassium channel. The primary functional roles of these channels include regulation of mitochondrial respiration and the alteration of membrane potential. Additionally, they modulate the mitochondrial matrix volume and the synthesis of reactive oxygen species by mitochondria. Mitochondrial potassium channels are believed to contribute to cytoprotection and cell death. In this paper, we discuss fundamental issues concerning mitochondrial potassium channels: their molecular identity, channel pharmacology and functional properties. Attention will be given to the current problems present in our understanding of the nature of mitochondrial potassium channels. This article is part of a Special Issue entitled 'EBEC 2016: 19th European Bioenergetics Conference, Riva del Garda, Italy, July 2-6, 2016', edited by Prof. Paolo Bernardi.
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Affiliation(s)
- Michał Laskowski
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, 3 Pasteur St., 02-093 Warsaw, Poland
| | - Bartłomiej Augustynek
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, 3 Pasteur St., 02-093 Warsaw, Poland
| | - Bogusz Kulawiak
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, 3 Pasteur St., 02-093 Warsaw, Poland
| | - Piotr Koprowski
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, 3 Pasteur St., 02-093 Warsaw, Poland
| | - Piotr Bednarczyk
- Department of Biophysics, Warsaw University of Life Sciences - SGGW, 159 Nowoursynowska St., 02-776 Warsaw, Poland
| | - Wieslawa Jarmuszkiewicz
- Laboratory of Bioenergetics, Faculty of Biology, Adam Mickiewicz University, Umultowska 89, 61-614 Poznan, Poland
| | - Adam Szewczyk
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, 3 Pasteur St., 02-093 Warsaw, Poland.
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24
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Han YE, Ryu SY, Park SH, Lee KH, Lee SH, Ho WK. Ca(2+) clearance by plasmalemmal NCLX, Li(+)-permeable Na(+)/Ca(2+) exchanger, is required for the sustained exocytosis in rat insulinoma INS-1 cells. Pflugers Arch 2015; 467:2461-72. [PMID: 26100674 DOI: 10.1007/s00424-015-1715-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2015] [Revised: 06/03/2015] [Accepted: 06/11/2015] [Indexed: 11/29/2022]
Abstract
Na(+)/Ca(2+) exchangers are key players for Ca(2+) clearance in pancreatic β-cells, but their molecular determinants and roles in insulin secretion are not fully understood. In the present study, we newly discovered that the Li(+)-permeable Na(+)/Ca(2+) exchangers (NCLX), which were known as mitochondrial Na(+)/Ca(2+) exchangers, contributed to the Na(+)-dependent Ca(2+) movement across the plasma membrane in rat INS-1 insulinoma cells. Na(+)/Ca(2+) exchange activity by NCLX was comparable to that by the Na(+)/Ca(2+) exchanger, NCX. We also confirmed the presence of NCLX proteins on the plasma membrane using immunocytochemistry and cell surface biotinylation experiments. We further investigated the role of NCLX on exocytosis function by measuring the capacitance increase in response to repetitive depolarization. Small interfering (si)RNA-mediated downregulation of NCLX did not affect the initial exocytosis, but significantly suppressed sustained exocytosis and recovery of exocytosis. XIP (NCX inhibitory peptide) or Na(+) replacement for inhibiting Na(+)-dependent Ca(2+) clearance also selectively suppressed sustained exocytosis. Consistent with the idea that sustained exocytosis requires ATP-dependent vesicle recruitment, mitochondrial function, assessed by mitochondrial membrane potential (ΔΨ), was impaired by siNCLX or XIP. However, depolarization-induced exocytosis was hardly affected by changes in intracellular Na(+) concentration, suggesting a negligible contribution of mitochondrial Na(+)/Ca(2+) exchanger. Taken together, our data indicate that Na(+)/Ca(2+) exchanger-mediated Ca(2+) clearance mediated by NCLX and NCX is crucial for optimizing mitochondrial function, which in turn contributes to vesicle recruitment for sustained exocytosis in pancreatic β-cells.
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Affiliation(s)
- Young-Eun Han
- Department of Physiology and Biomembrane Plasticity Research Center, Seoul National University College of Medicine, 103 Daehak-ro, Jongno-gu, Seoul, 110-799, Republic of Korea
| | - Shin-Young Ryu
- Department of Physiology and Biomembrane Plasticity Research Center, Seoul National University College of Medicine, 103 Daehak-ro, Jongno-gu, Seoul, 110-799, Republic of Korea
| | - Sun-Hyun Park
- Department of Physiology and Biomembrane Plasticity Research Center, Seoul National University College of Medicine, 103 Daehak-ro, Jongno-gu, Seoul, 110-799, Republic of Korea
| | - Kyu-Hee Lee
- Department of Physiology and Biomembrane Plasticity Research Center, Seoul National University College of Medicine, 103 Daehak-ro, Jongno-gu, Seoul, 110-799, Republic of Korea
| | - Suk-Ho Lee
- Department of Physiology and Biomembrane Plasticity Research Center, Seoul National University College of Medicine, 103 Daehak-ro, Jongno-gu, Seoul, 110-799, Republic of Korea
| | - Won-Kyung Ho
- Department of Physiology and Biomembrane Plasticity Research Center, Seoul National University College of Medicine, 103 Daehak-ro, Jongno-gu, Seoul, 110-799, Republic of Korea.
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