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Velmurugan S, Liu T, Chen KC, Despa F, O'Rourke B, Despa S. Distinct Effects of Mitochondrial Na +/Ca 2+ Exchanger Inhibition and Ca 2+ Uniporter Activation on Ca 2+ Sparks and Arrhythmogenesis in Diabetic Rats. J Am Heart Assoc 2023; 12:e029997. [PMID: 37421267 PMCID: PMC10382117 DOI: 10.1161/jaha.123.029997] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/25/2023] [Accepted: 05/26/2023] [Indexed: 07/10/2023]
Abstract
Background Mitochondrial dysfunction contributes to the cardiac remodeling triggered by type 2 diabetes (T2D). Mitochondrial Ca2+ concentration ([Ca2+]m) modulates the oxidative state and cytosolic Ca2+ regulation. Thus, we investigated how T2D affects mitochondrial Ca2+ fluxes, the downstream consequences on myocyte function, and the effects of normalizing mitochondrial Ca2+ transport. Methods and Results We compared myocytes/hearts from transgenic rats with late-onset T2D (rats that develop late-onset T2D due to heterozygous expression of human amylin in the pancreatic β-cells [HIP] model) and their nondiabetic wild-type (WT) littermates. [Ca2+]m was significantly lower in myocytes from diabetic HIP rats compared with WT cells. Ca2+ extrusion through the mitochondrial Na+/Ca2+ exchanger (mitoNCX) was elevated in HIP versus WT myocytes, particularly at moderate and high [Ca2+]m, while mitochondrial Ca2+ uptake was diminished. Mitochondrial Na+ concentration was comparable in WT and HIP rat myocytes and remained remarkably stable while manipulating mitoNCX activity. Lower [Ca2+]m was associated with oxidative stress, increased sarcoplasmic reticulum Ca2+ leak in the form of Ca2+ sparks, and mitochondrial dysfunction in T2D hearts. MitoNCX inhibition with CGP-37157 reduced oxidative stress, Ca2+ spark frequency, and stress-induced arrhythmias in HIP rat hearts while having no significant effect in WT rats. In contrast, activation of the mitochondrial Ca2+ uniporter with SB-202190 enhanced spontaneous sarcoplasmic reticulum Ca2+ release and had no significant effect on arrhythmias in both WT and HIP rat hearts. Conclusions [Ca2+]m is reduced in myocytes from rats with T2D due to a combination of exacerbated mitochondrial Ca2+ extrusion through mitoNCX and impaired mitochondrial Ca2+ uptake. Partial mitoNCX inhibition limits sarcoplasmic reticulum Ca2+ leak and arrhythmias in T2D hearts, whereas mitochondrial Ca2+ uniporter activation does not.
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Affiliation(s)
- Sathya Velmurugan
- Department of Pharmacology and Nutritional SciencesUniversity of KentuckyLexingtonKYUSA
| | - Ting Liu
- Division of Cardiology, Department of MedicineThe Johns Hopkins UniversityBaltimoreMDUSA
| | - Kuey C. Chen
- Department of Pharmacology and Nutritional SciencesUniversity of KentuckyLexingtonKYUSA
| | - Florin Despa
- Department of Pharmacology and Nutritional SciencesUniversity of KentuckyLexingtonKYUSA
| | - Brian O'Rourke
- Division of Cardiology, Department of MedicineThe Johns Hopkins UniversityBaltimoreMDUSA
| | - Sanda Despa
- Department of Pharmacology and Nutritional SciencesUniversity of KentuckyLexingtonKYUSA
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2
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Ashok D, Papanicolaou K, Sidor A, Wang M, Solhjoo S, Liu T, O'Rourke B. Mitochondrial membrane potential instability on reperfusion after ischemia does not depend on mitochondrial Ca 2+ uptake. J Biol Chem 2023; 299:104708. [PMID: 37061004 PMCID: PMC10206190 DOI: 10.1016/j.jbc.2023.104708] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Revised: 03/21/2023] [Accepted: 04/09/2023] [Indexed: 04/17/2023] Open
Abstract
Physiologic Ca2+ entry via the Mitochondrial Calcium Uniporter (MCU) participates in energetic adaption to workload but may also contribute to cell death during ischemia/reperfusion (I/R) injury. The MCU has been identified as the primary mode of Ca2+ import into mitochondria. Several groups have tested the hypothesis that Ca2+ import via MCU is detrimental during I/R injury using genetically-engineered mouse models, yet the results from these studies are inconclusive. Furthermore, mitochondria exhibit unstable or oscillatory membrane potentials (ΔΨm) when subjected to stress, such as during I/R, but it is unclear if the primary trigger is an excess influx of mitochondrial Ca2+ (mCa2+), reactive oxygen species (ROS) accumulation, or other factors. Here, we critically examine whether MCU-mediated mitochondrial Ca2+ uptake during I/R is involved in ΔΨm instability, or sustained mitochondrial depolarization, during reperfusion by acutely knocking out MCU in neonatal mouse ventricular myocyte (NMVM) monolayers subjected to simulated I/R. Unexpectedly, we find that MCU knockout does not significantly alter mCa2+ import during I/R, nor does it affect ΔΨm recovery during reperfusion. In contrast, blocking the mitochondrial sodium-calcium exchanger (mNCE) suppressed the mCa2+ increase during Ischemia but did not affect ΔΨm recovery or the frequency of ΔΨm oscillations during reperfusion, indicating that mitochondrial ΔΨm instability on reperfusion is not triggered by mCa2+. Interestingly, inhibition of mitochondrial electron transport or supplementation with antioxidants stabilized I/R-induced ΔΨm oscillations. The findings are consistent with mCa2+ overload being mediated by reverse-mode mNCE activity and supporting ROS-induced ROS release as the primary trigger of ΔΨm instability during reperfusion injury.
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Affiliation(s)
- Deepthi Ashok
- Johns Hopkins University, Division of Cardiology, Department of Medicine, Baltimore, Maryland, USA
| | - Kyriakos Papanicolaou
- Johns Hopkins University, Division of Cardiology, Department of Medicine, Baltimore, Maryland, USA
| | - Agnieszka Sidor
- Johns Hopkins University, Division of Cardiology, Department of Medicine, Baltimore, Maryland, USA
| | - Michelle Wang
- Johns Hopkins University, Division of Cardiology, Department of Medicine, Baltimore, Maryland, USA
| | - Soroosh Solhjoo
- Johns Hopkins University, Division of Cardiology, Department of Medicine, Baltimore, Maryland, USA
| | - Ting Liu
- Johns Hopkins University, Division of Cardiology, Department of Medicine, Baltimore, Maryland, USA
| | - Brian O'Rourke
- Johns Hopkins University, Division of Cardiology, Department of Medicine, Baltimore, Maryland, USA.
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de los Ríos C, Viejo L, Carretero VJ, Juárez NH, Cruz-Martins N, Hernández-Guijo JM. Promising Molecular Targets in Pharmacological Therapy for Neuronal Damage in Brain Injury. Antioxidants (Basel) 2023; 12:118. [PMID: 36670980 PMCID: PMC9854812 DOI: 10.3390/antiox12010118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2022] [Revised: 12/19/2022] [Accepted: 12/27/2022] [Indexed: 01/05/2023] Open
Abstract
The complex etiopathogenesis of brain injury associated with neurodegeneration has sparked a lot of studies in the last century. These clinical situations are incurable, and the currently available therapies merely act on symptoms or slow down the course of the diseases. Effective methods are being sought with an intent to modify the disease, directly acting on the properly studied targets, as well as to contribute to the development of effective therapeutic strategies, opening the possibility of refocusing on drug development for disease management. In this sense, this review discusses the available evidence for mitochondrial dysfunction induced by Ca2+ miscommunication in neurons, as well as how targeting phosphorylation events may be used to modulate protein phosphatase 2A (PP2A) activity in the treatment of neuronal damage. Ca2+ tends to be the catalyst for mitochondrial dysfunction, contributing to the synaptic deficiency seen in brain injury. Additionally, emerging data have shown that PP2A-activating drugs (PADs) suppress inflammatory responses by inhibiting different signaling pathways, indicating that PADs may be beneficial for the management of neuronal damage. In addition, a few bioactive compounds have also triggered the activation of PP2A-targeted drugs for this treatment, and clinical studies will help in the authentication of these compounds. If the safety profiles of PADs are proven to be satisfactory, there is a case to be made for starting clinical studies in the setting of neurological diseases as quickly as possible.
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Affiliation(s)
- Cristóbal de los Ríos
- Department of Pharmacology and Therapeutic and Teófilo Hernando Institute, Faculty of Medicine, University Autónoma de Madrid, C/. Arzobispo Morcillo 4, 28029 Madrid, Spain
- Departamento de Ciencias Básicas de la Salud, University Rey Juan Carlos, Avda. Atenas s/n, 28922 Alcorcón, Spain
| | - Lucía Viejo
- Department of Pharmacology and Therapeutic and Teófilo Hernando Institute, Faculty of Medicine, University Autónoma de Madrid, C/. Arzobispo Morcillo 4, 28029 Madrid, Spain
| | - Victoria Jiménez Carretero
- Department of Pharmacology and Therapeutic and Teófilo Hernando Institute, Faculty of Medicine, University Autónoma de Madrid, C/. Arzobispo Morcillo 4, 28029 Madrid, Spain
| | - Natalia Hernández Juárez
- Department of Pharmacology and Therapeutic and Teófilo Hernando Institute, Faculty of Medicine, University Autónoma de Madrid, C/. Arzobispo Morcillo 4, 28029 Madrid, Spain
| | - Natália Cruz-Martins
- Faculty of Medicine, Institute for Research and Innovation in Health (i3S), University of Porto, 4200-319 Porto, Portugal
- Institute for Research and Advanced Training in Health Sciences and Technologies, Rua Central de Gandra, 1317, 4585-116 Gandra, Portugal
| | - Jesús M. Hernández-Guijo
- Department of Pharmacology and Therapeutic and Teófilo Hernando Institute, Faculty of Medicine, University Autónoma de Madrid, C/. Arzobispo Morcillo 4, 28029 Madrid, Spain
- Ramón y Cajal Institute for Health Research, IRYCIS, Hospital Ramón y Cajal, Ctra. de Colmenar Viejo, Km. 9,100, 28029 Madrid, Spain
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4
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Takeuchi A, Matsuoka S. Spatial and Functional Crosstalk between the Mitochondrial Na+-Ca2+ Exchanger NCLX and the Sarcoplasmic Reticulum Ca2+ Pump SERCA in Cardiomyocytes. Int J Mol Sci 2022; 23:ijms23147948. [PMID: 35887296 PMCID: PMC9317594 DOI: 10.3390/ijms23147948] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 07/13/2022] [Accepted: 07/16/2022] [Indexed: 02/05/2023] Open
Abstract
The mitochondrial Na+-Ca2+ exchanger, NCLX, was reported to supply Ca2+ to sarcoplasmic reticulum (SR)/endoplasmic reticulum, thereby modulating various cellular functions such as the rhythmicity of cardiomyocytes, and cellular Ca2+ signaling upon antigen receptor stimulation and chemotaxis in B lymphocytes; however, there is little information on the spatial relationships of NCLX with SR Ca2+ handling proteins, and their physiological impact. Here we examined the issue, focusing on the interaction of NCLX with an SR Ca2+ pump SERCA in cardiomyocytes. A bimolecular fluorescence complementation assay using HEK293 cells revealed that the exogenously expressed NCLX was localized in close proximity to four exogenously expressed SERCA isoforms. Immunofluorescence analyses of isolated ventricular myocytes showed that the NCLX was localized to the edges of the mitochondria, forming a striped pattern. The co-localization coefficients in the super-resolution images were higher for NCLX–SERCA2, than for NCLX–ryanodine receptor and NCLX–Na+/K+ ATPase α-1 subunit, confirming the close localization of endogenous NCLX and SERCA2 in cardiomyocytes. The mathematical model implemented with the spatial and functional coupling of NCLX and SERCA well reproduced the NCLX inhibition-mediated modulations of SR Ca2+ reuptake in HL-1 cardiomyocytes. Taken together, these results indicated that NCLX and SERCA are spatially and functionally coupled in cardiomyocytes.
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Affiliation(s)
- Ayako Takeuchi
- Department of Integrative and Systems Physiology, Faculty of Medical Sciences, University of Fukui, Fukui 910-1193, Japan
- Life Science Innovation Center, University of Fukui, Fukui 910-1193, Japan
- Correspondence: ; Tel.: +81-776-61-8311
| | - Satoshi Matsuoka
- Department of Integrative and Systems Physiology, Faculty of Medical Sciences, University of Fukui, Fukui 910-1193, Japan
- Life Science Innovation Center, University of Fukui, Fukui 910-1193, Japan
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5
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Abstract
The uptake of calcium into and extrusion of calcium from the mitochondrial matrix is a fundamental biological process that has critical effects on cellular metabolism, signaling, and survival. Disruption of mitochondrial calcium (mCa2+) cycling is implicated in numerous acquired diseases such as heart failure, stroke, neurodegeneration, diabetes, and cancer, and is genetically linked to several inherited neuromuscular disorders. Understanding the mechanisms responsible for mCa2+ exchange therefore holds great promise for the treatment of these diseases. The past decade has seen the genetic identification of many of the key proteins that mediate mitochondrial calcium uptake and efflux. Here, we present an overview of the phenomenon of mCa2+ transport, and a comprehensive examination of the molecular machinery that mediates calcium flux across the inner mitochondrial membrane: the mitochondrial uniporter complex (consisting of MCU, EMRE, MICU1, MICU2, MICU3, MCUB, and MCUR1), NCLX, LETM1, the mitochondrial ryanodine receptor, and the mitochondrial permeability transition pore. We then consider the physiological implications of mCa2+ flux and evaluate how alterations in mCa2+ homeostasis contribute to human disease. This review concludes by highlighting opportunities and challenges for therapeutic intervention in pathologies characterized by aberrant mCa2+ handling and by summarizing critical unanswered questions regarding the biology of mCa2+ flux.
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Affiliation(s)
- Joanne F Garbincius
- Center for Translational Medicine, Center for Translational Medicine, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, United States
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Mitochondrial dysfunctions associated with chronic respiratory diseases and their targeted therapies: an update. Future Med Chem 2021; 13:1249-1251. [PMID: 34184585 DOI: 10.4155/fmc-2021-0097] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
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7
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Assali EA, Sekler I. Sprinkling salt on mitochondria: The metabolic and pathophysiological roles of mitochondrial Na + signaling mediated by NCLX. Cell Calcium 2021; 97:102416. [PMID: 34062329 DOI: 10.1016/j.ceca.2021.102416] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 04/25/2021] [Accepted: 04/26/2021] [Indexed: 11/25/2022]
Abstract
NCLX, the mitochondrial Na+/Ca2+ transporter is a key player in Ca2+ signaling. However, its role in Na+ signaling is poorly understood. In this review we focus on Na+ signaling by NCLX, and discuss recent physiological and pathophysiological roles attributed to the Na+ influx into mitochondria.
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Affiliation(s)
- Essam A Assali
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University, Beer-Sheva, 84105, Israel
| | - Israel Sekler
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University, Beer-Sheva, 84105, Israel.
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8
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Mitochondrial Calcium Signaling in Pancreatic β-Cell. Int J Mol Sci 2021; 22:ijms22052515. [PMID: 33802289 PMCID: PMC7959128 DOI: 10.3390/ijms22052515] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Revised: 02/22/2021] [Accepted: 02/26/2021] [Indexed: 12/13/2022] Open
Abstract
Accumulation of calcium in energized mitochondria of pancreatic β-cells is emerging as a crucial process for pancreatic β-cell function. β-cell mitochondria sense and shape calcium signals, linking the metabolism of glucose and other secretagogues to the generation of signals that promote insulin secretion during nutrient stimulation. Here, we describe the role of mitochondrial calcium signaling in pancreatic β-cell function. We report the latest pharmacological and genetic findings, including the first mitochondrial calcium-targeted intervention strategies developed to modulate pancreatic β-cell function and their potential relevance in the context of diabetes.
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9
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Spermatic mitochondria: role in oxidative homeostasis, sperm function and possible tools for their assessment. ZYGOTE 2018; 26:251-260. [PMID: 30223916 DOI: 10.1017/s0967199418000242] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
SummaryDespite sperm mitochondrial relevance to the fertilization capacity, the processes involved in the production of ATP and functional dynamics of sperm mitochondria are not fully understood. One of these processes is the paradox involved between function and formation of reactive oxygen species performed by the organelle. Therefore, this review aimed to provide data on the role of sperm mitochondria in oxidative homeostasis and functionality as well the tools to assess sperm mitochondrial function.
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10
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López-Gil A, Nanclares C, Méndez-López I, Martínez-Ramírez C, de Los Rios C, Padín-Nogueira JF, Montero M, Gandía L, García AG. The quantal catecholamine release from mouse chromaffin cells challenged with repeated ACh pulses is regulated by the mitochondrial Na + /Ca 2+ exchanger. J Physiol 2017; 595:2129-2146. [PMID: 27982456 DOI: 10.1113/jp273339] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2016] [Accepted: 11/30/2016] [Indexed: 01/09/2023] Open
Abstract
KEY POINTS Upon repeated application of short ACh pulses to C57BL6J mouse chromaffin cells, the amperometrically monitored secretory responses promptly decayed to a steady-state level of around 25% of the initial response. A subsequent K+ pulse, however, overcame such decay. These data suggest that mouse chromaffin cells have a ready release-vesicle pool that is selectively recruited by the physiological neurotransmitter ACh. The ACh-sensitive vesicle pool is refilled and maintained by the rate of Ca2+ delivery from mitochondria to the cytosol, through the mitochondrial Na+ /Ca2+ exchanger (mNCX). ITH12662, a novel blocker of the mNCX, prevented the decay of secretion elicited by ACh pulses and delayed the rate of [Ca2+ ]c clearance. This regulatory pathway may be physiologically relevant in situations of prolonged stressful conflicts where a sustained catecholamine release is regulated by mitochondrial Ca2+ circulation through the mNCX, which couples respiration and ATP synthesis to long-term stimulation of chromaffin cells by endogenously released ACh. ABSTRACT Using caged-Ca2+ photorelease or paired depolarising pulses in voltage-clamped chromaffin cells (CCs), various pools of secretory vesicles with different readiness to undergo exocytosis have been identified. Whether these pools are present in unclamped CCs challenged with ACh, the physiological neurotransmitter at the splanchnic nerve-CC synapse, is unknown. We have explored here whether an ACh-sensitive ready-release vesicle pool (ASP) is present in C57BL6J mouse chromaffin cells (MCCs). Single cells were fast perfused with a Tyrode solution at 37°C, and challenged with 12 sequential ACh pulses (100 μm, 2 s, every 30 s) plus a K+ pulse given at the end (75 mm K+ ). After the first 2-3 ACh pulses the amperometrically monitored secretory responses promptly decayed to a steady-state level of around 25% of the initial response. The last K+ pulse, however, overcame such decay. Repeated ACh pulses to voltage-clamped cells elicited non-desensitising nicotinic currents. Also, the [Ca2+ ]c transients elicited by repeated ACh pulses that were superimposed on a stable baseline elevation did not undergo decay. The novel blocker of the mitochondrial Na+ /Ca2+ exchanger (mNCX) ITH12662 prevented the decay of secretion elicited by ACh pulses and delayed the rate of [Ca2+ ]c clearance. The experiments are compatible with the idea that C57BL6J MCCs have an ASP vesicle pool that is selectively recruited by the physiological neurotransmitter ACh and is regulated by the rate of Ca2+ delivery from mitochondria to the cytosol, through the mNCX.
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Affiliation(s)
- Angela López-Gil
- Instituto Teófilo Hernando, Universidad Autónoma de Madrid, C/ Arzobispo Morcillo, 4, 28029, Madrid, Spain
| | - Carmen Nanclares
- Instituto Teófilo Hernando, Universidad Autónoma de Madrid, C/ Arzobispo Morcillo, 4, 28029, Madrid, Spain.,Departamento de Farmacología y Terapéutica, Facultad de Medicina, Universidad Autónoma de Madrid, C/ Arzobispo Morcillo, 4, 28029, Madrid, Spain
| | - Iago Méndez-López
- Instituto Teófilo Hernando, Universidad Autónoma de Madrid, C/ Arzobispo Morcillo, 4, 28029, Madrid, Spain.,Departamento de Farmacología y Terapéutica, Facultad de Medicina, Universidad Autónoma de Madrid, C/ Arzobispo Morcillo, 4, 28029, Madrid, Spain
| | - Carmen Martínez-Ramírez
- Instituto Teófilo Hernando, Universidad Autónoma de Madrid, C/ Arzobispo Morcillo, 4, 28029, Madrid, Spain.,Departamento de Farmacología y Terapéutica, Facultad de Medicina, Universidad Autónoma de Madrid, C/ Arzobispo Morcillo, 4, 28029, Madrid, Spain
| | - Cristóbal de Los Rios
- Instituto Teófilo Hernando, Universidad Autónoma de Madrid, C/ Arzobispo Morcillo, 4, 28029, Madrid, Spain.,Instituto de Investigación Sanitaria, Hospital Universitario de la Princesa, Universidad Autónoma de Madrid, c/ Diego de León, 62, 28006, Madrid, Spain
| | - J Fernando Padín-Nogueira
- Instituto Teófilo Hernando, Universidad Autónoma de Madrid, C/ Arzobispo Morcillo, 4, 28029, Madrid, Spain.,Departamento de Farmacología y Terapéutica, Facultad de Medicina, Universidad Autónoma de Madrid, C/ Arzobispo Morcillo, 4, 28029, Madrid, Spain
| | - Mayte Montero
- Instituto de Biologia y Genética Molecular, Universidad de Valladolid, c/ Sanz y Forés, 3, 47003, Valladolid, Spain
| | - Luis Gandía
- Instituto Teófilo Hernando, Universidad Autónoma de Madrid, C/ Arzobispo Morcillo, 4, 28029, Madrid, Spain.,Departamento de Farmacología y Terapéutica, Facultad de Medicina, Universidad Autónoma de Madrid, C/ Arzobispo Morcillo, 4, 28029, Madrid, Spain
| | - Antonio G García
- Instituto Teófilo Hernando, Universidad Autónoma de Madrid, C/ Arzobispo Morcillo, 4, 28029, Madrid, Spain.,Departamento de Farmacología y Terapéutica, Facultad de Medicina, Universidad Autónoma de Madrid, C/ Arzobispo Morcillo, 4, 28029, Madrid, Spain.,Instituto de Investigación Sanitaria, Hospital Universitario de la Princesa, Universidad Autónoma de Madrid, c/ Diego de León, 62, 28006, Madrid, Spain
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11
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Roles of the mitochondrial Na(+)-Ca(2+) exchanger, NCLX, in B lymphocyte chemotaxis. Sci Rep 2016; 6:28378. [PMID: 27328625 PMCID: PMC4916421 DOI: 10.1038/srep28378] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Accepted: 06/03/2016] [Indexed: 12/21/2022] Open
Abstract
Lymphocyte chemotaxis plays important roles in immunological reactions, although the mechanism of its regulation is still unclear. We found that the cytosolic Na(+)-dependent mitochondrial Ca(2+) efflux transporter, NCLX, regulates B lymphocyte chemotaxis. Inhibiting or silencing NCLX in A20 and DT40 B lymphocytes markedly increased random migration and suppressed the chemotactic response to CXCL12. In contrast to control cells, cytosolic Ca(2+) was higher and was not increased further by CXCL12 in NCLX-knockdown A20 B lymphocytes. Chelating intracellular Ca(2+) with BAPTA-AM disturbed CXCL12-induced chemotaxis, suggesting that modulation of cytosolic Ca(2+) via NCLX, and thereby Rac1 activation and F-actin polymerization, is essential for B lymphocyte motility and chemotaxis. Mitochondrial polarization, which is necessary for directional movement, was unaltered in NCLX-knockdown cells, although CXCL12 application failed to induce enhancement of mitochondrial polarization, in contrast to control cells. Mouse spleen B lymphocytes were similar to the cell lines, in that pharmacological inhibition of NCLX by CGP-37157 diminished CXCL12-induced chemotaxis. Unexpectedly, spleen T lymphocyte chemotaxis was unaffected by CGP-37157 treatment, indicating that NCLX-mediated regulation of chemotaxis is B lymphocyte-specific, and mitochondria-endoplasmic reticulum Ca(2+) dynamics are more important in B lymphocytes than in T lymphocytes. We conclude that NCLX is pivotal for B lymphocyte motility and chemotaxis.
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12
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Life after the birth of the mitochondrial Na+/Ca2+ exchanger, NCLX. SCIENCE CHINA-LIFE SCIENCES 2015; 58:59-65. [DOI: 10.1007/s11427-014-4789-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2014] [Accepted: 10/17/2014] [Indexed: 02/07/2023]
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13
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Gilon P, Chae HY, Rutter GA, Ravier MA. Calcium signaling in pancreatic β-cells in health and in Type 2 diabetes. Cell Calcium 2014; 56:340-61. [DOI: 10.1016/j.ceca.2014.09.001] [Citation(s) in RCA: 116] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Revised: 08/26/2014] [Accepted: 09/01/2014] [Indexed: 12/24/2022]
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Caricati-Neto A, Padín JF, Silva-Junior ED, Fernández-Morales JC, de Diego AMG, Jurkiewicz A, García AG. Novel features on the regulation by mitochondria of calcium and secretion transients in chromaffin cells challenged with acetylcholine at 37°C. Physiol Rep 2013; 1:e00182. [PMID: 24744861 PMCID: PMC3970745 DOI: 10.1002/phy2.182] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2013] [Accepted: 11/01/2013] [Indexed: 01/14/2023] Open
Abstract
From experiments performed at room temperature, we know that the buffering of Ca2+ by mitochondria contributes to the shaping of the bulk cytosolic calcium transient ([Ca2+]c) and secretion transients of chromaffin cells stimulated with depolarizing pulses. We also know that the mitochondrial Ca2+ transporters and the release of catecholamine are faster at 37°C with respect to room temperature. Therefore, we planned this investigation to gain further insight into the contribution of mitochondrial Ca2+ buffering to the shaping of [Ca2+]c and catecholamine release transients, using some novel experimental conditions that have not been yet explored namely: (1) perifusion of bovine chromaffin cells (BCCs) with saline at 37°C and their repeated challenging with the physiological neurotransmitter acetylcholine (ACh); (2) separate blockade of mitochondrial Ca2+ uniporter (mCUP) with Ru360 or the mitochondrial Na+/Ca2+ exchanger (mNCX) with CGP37157; (3) full blockade of the mitochondrial Ca2+ cycling (mCC) by the simultaneous inhibition of the mCUP and the mNCX. Ru360 caused a pronounced delay of [Ca2+]c clearance and augmented secretion. In contrast, CGP37157 only caused a tiny delay of [Ca2+]c clearance and a mild decrease in secretion. The mCC resulting in continued Ca2+ uptake and its release back into the cytosol was interrupted by combined Ru360 + CGP37157 (Ru/CGP), the protonophore carbonyl cyanide‐p‐trifluoromethoxyphenylhydrazone, or combined oligomycin + rotenone (O/R); these three treatments caused a mild but sustained elevation of basal [Ca2+]c that, however, was not accompanied by a parallel increase in basal secretion. Nevertheless, all treatments caused a pronounced augmentation of ACh‐induced secretion, with minor changes of the ACh‐induced [Ca2+]c transients. Combined Ru/CGP did not alter the resting membrane potential in current‐clamped cells. Additionally, Ru/CGP did not increase basal [Ca2+]c near subplasmalemmal sites and caused a mild decrease in the size of the readily releasable vesicle pool. Our results provide new functional features in support of the view that in BCCs there are two subpopulations of mitochondria, M1 underneath the plasmalemma nearby exocytotic sites and M2 at the core cell nearby vesicle transport sites. While M1 serves to shape the ACh‐elicited exocytotic response through its efficient Ca2+ removal by the mCUP, M2 shapes the lower [Ca2+]c elevations required for new vesicle supply to the exocytotic machinery, from the large reserve vesicle pool at the cell core. The mCUP of the M1 pool seems to play a more prominent role in controlling the ACh responses, in comparison with the mNCX. Regulation by mitochondria of exocytosis at 37°C.
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Affiliation(s)
- Afonso Caricati-Neto
- Departamento de Farmacología, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Juan-Fernando Padín
- Instituto Teófilo Hernando, Facultad de Medicina, Universidad Autónoma de Madrid, C/Arzobispo Morcillo, 4, Madrid, 28029, Spain ; Departamento de Farmacología y Terapéutica, Facultad de Medicina, Universidad Autónoma de Madrid, C/Arzobispo Morcillo, 4, 28029Madrid, Spain
| | - Edilson-Dantas Silva-Junior
- Departamento de Farmacología, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - José-Carlos Fernández-Morales
- Instituto Teófilo Hernando, Facultad de Medicina, Universidad Autónoma de Madrid, C/Arzobispo Morcillo, 4, Madrid, 28029, Spain ; Departamento de Farmacología y Terapéutica, Facultad de Medicina, Universidad Autónoma de Madrid, C/Arzobispo Morcillo, 4, 28029Madrid, Spain
| | - Antonio-Miguel G de Diego
- Instituto Teófilo Hernando, Facultad de Medicina, Universidad Autónoma de Madrid, C/Arzobispo Morcillo, 4, Madrid, 28029, Spain ; Departamento de Farmacología y Terapéutica, Facultad de Medicina, Universidad Autónoma de Madrid, C/Arzobispo Morcillo, 4, 28029Madrid, Spain
| | - Aron Jurkiewicz
- Departamento de Farmacología, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Antonio G García
- Instituto Teófilo Hernando, Facultad de Medicina, Universidad Autónoma de Madrid, C/Arzobispo Morcillo, 4, Madrid, 28029, Spain ; Departamento de Farmacología y Terapéutica, Facultad de Medicina, Universidad Autónoma de Madrid, C/Arzobispo Morcillo, 4, 28029Madrid, Spain ; Servicio de Farmacología Clínica, Instituto de Investigación Sanitaria, Hospital Universitario de la Princesa, Universidad Autónoma de Madrid, C/Diego de León, 62, Madrid, 28006, Spain
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The mitochondrial Na+-Ca2+ exchanger, NCLX, regulates automaticity of HL-1 cardiomyocytes. Sci Rep 2013; 3:2766. [PMID: 24067497 PMCID: PMC3783885 DOI: 10.1038/srep02766] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2013] [Accepted: 09/05/2013] [Indexed: 01/10/2023] Open
Abstract
Mitochondrial Ca2+ is known to change dynamically, regulating mitochondrial as well as cellular functions such as energy metabolism and apoptosis. The NCLX gene encodes the mitochondrial Na+-Ca2+ exchanger (NCXmit), a Ca2+ extrusion system in mitochondria. Here we report that the NCLX regulates automaticity of the HL-1 cardiomyocytes. NCLX knockdown using siRNA resulted in the marked prolongation of the cycle length of spontaneous Ca2+ oscillation and action potential generation. The upstrokes of action potential and Ca2+ transient were markedly slower, and sarcoplasmic reticulum (SR) Ca2+ handling were compromised in the NCLX knockdown cells. Analyses using a mathematical model of HL-1 cardiomyocytes demonstrated that blocking NCXmit reduced the SR Ca2+ content to slow spontaneous SR Ca2+ leak, which is a trigger of automaticity. We propose that NCLX is a novel molecule to regulate automaticity of cardiomyocytes via modulating SR Ca2+ handling.
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Effect of β3-adrenergic receptor on atrial L-type Ca(2+) current in rats with chronic heart failure. Heart Lung Circ 2013; 23:369-77. [PMID: 24055266 DOI: 10.1016/j.hlc.2013.08.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2013] [Revised: 08/18/2013] [Accepted: 08/20/2013] [Indexed: 11/22/2022]
Abstract
OBJECTIVES To investigate the effect of selective β3-adrenoreceptor agonist BRL-37344 on L-type Ca(2+) current (Ica,L) and mRNA expression of L-type Ca(2+) channel α2δ-2 (Cacna2d2) in rats with chronic heart failure (CHF). METHODS Twenty-four male Wistar rats were divided into normal control (n=6) and CHF group (n=18), which were further divided into CHF control and BRL group (0.4nmol/kg, IV, twice weekly for four weeks). Echocardiography was performed to assess the structure and function of the left atrium (LA). RESULTS The LA in the BRL group (4.4 ± 0.2mm) was larger than in the normal control (3.5 ± 0.3mm, P<0.01) or CHF control (4.0 ± 0.2mm, P<0.05) group. The LA ejection fraction in the BRL group (36.2 ± 4.2%) was lower than in the normal control (58.0 ± 3.1%, P<0.01) or CHF control group (42.3 ± 4.8%, P<0.05). There was no difference in Ica,L density between the BRL group and CHF control group (8.3 ± 1.7 vs. 8.2 ± 2.6 pA/pF, P>0.05), which was higher than in the normal control group (6.0 ± 1.8 pA/pF, P<0.01). There was no difference in the mRNA expression of α2δ-2 (Cacna2d2) between the BRL group and CHF control group (0.264 ± 0.005 vs. 0.243 ± 0.017, P>0.05), which was also higher than in the normal control group (0.137 ± 0.013, P<0.01). CONCLUSION β3-Adrenoreceptor stimulation with BRL-37344 was associated with an increase in LA diameter and a decrease in LA function in chronic heart failure. These structural and function changes were not related to Ica,L or L-type Ca(2+) channel α2δ-2 (Cacna2d2) subunit in the LA myocytes.
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Mitochondrial exchanger NCLX plays a major role in the intracellular Ca2+ signaling, gliotransmission, and proliferation of astrocytes. J Neurosci 2013; 33:7206-19. [PMID: 23616530 DOI: 10.1523/jneurosci.5721-12.2013] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Mitochondria not only provide cells with energy, but are central to Ca(2+) signaling. Powered by the mitochondrial membrane potential, Ca(2+) enters the mitochondria and is released into the cytosol through a mitochondrial Na(+)/Ca(2+) exchanger. We established that NCLX, a newly discovered mitochondrial Na(+)/Ca(2+) exchanger, is expressed in astrocytes isolated from mice of either sex. Immunoblot analysis of organellar fractions showed that the location of NCLX is confined to mitochondria. Using pericam-based mitochondrial Ca(2+) imaging and NCLX inhibition either by siRNA or by the pharmacological blocker CGP37157, we demonstrated that NCLX is responsible for mitochondrial Ca(2+) extrusion. Suppression of NCLX function altered cytosolic Ca(2+) dynamics in astrocytes and this was mediated by a strong effect of NCLX activity on Ca(2+) influx via store-operated entry. Furthermore, Ca(2+) influx through the store-operated Ca(2+) entry triggered strong, whereas ER Ca(2+) release triggered only modest mitochondrial Ca(2+) transients, indicating that the functional cross talk between the plasma membrane and mitochondrial domains is particularly strong in astrocytes. Finally, silencing of NCLX expression significantly reduced Ca(2+)-dependent processes in astrocytes (i.e., exocytotic glutamate release, in vitro wound closure, and proliferation), whereas Ca(2+) wave propagation was not affected. Therefore, NCLX, by meditating astrocytic mitochondrial Na(+)/Ca(2+) exchange, links between mitochondria and plasma membrane Ca(2+) signaling, thereby modulating cytoplasmic Ca(2+) transients required to control a diverse array of astrocyte functions.
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18
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Ragone MI, Torres NS, Consolini AE. Energetic study of cardioplegic hearts under ischaemia/reperfusion and [Ca(2+)] changes in cardiomyocytes of guinea-pig: mitochondrial role. Acta Physiol (Oxf) 2013; 207:369-84. [PMID: 23171431 DOI: 10.1111/apha.12027] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2012] [Revised: 09/08/2012] [Accepted: 10/02/2012] [Indexed: 12/25/2022]
Abstract
AIM To study the role of mitochondria in the recovery of guinea-pig hearts exposed to high-K(+)-cardioplegia (CPG) and ischaemia/reperfusion (I/R) METHODS: We measured contractility and heat release in perfused guinea-pig hearts and cytosolic and mitochondrial Ca(2+) by epifluorescence and confocal microscopy in isolated cardiomyocytes loaded with Fluo-4 or Rhod-2. RESULTS In hearts, CPG increased the postischaemic contractile recovery, and this was potentiated by the mNCX blocker clonazepam and the mKATP opener diazoxide, which also prevented the fall in muscle economy. Moreover, CPG prevented the stunning induced by ouabain, which was reduced by clonazepam. In cardiomyocytes, CPG increased fluorescent signals of cytosolic and mitochondrial Ca(2+), while the addition of a mNCX blocker (CGP37157) increased cytosolic but reduced mitochondrial [Ca(2+)]. Ouabain in CPG increased cytosolic Ca(2+) and resting heat, but the addition of CGP37157 reduced them, as well as mitochondrial Ca(2+). CONCLUSIONS CPG, diazoxide and clonazepam improve postischaemic recovery, respectively, by increasing the Ca(2+) cycling and by reducing the mitochondrial Ca(2+) uptake either by uniporter or by mNCX. The mitochondria compete with the leaky sarcoplasmic reticulum (SR) as sink of Ca(2+) in guinea-pig hearts, affecting the postischaemic contractility. CPG also prevented the ouabain-induced dysfunction by avoiding the Ca(2+) overload. Ouabain reduced the synergism between CPG and clonazepam suggesting that [Na(+)]i and SR load influence the mNCX role.
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Affiliation(s)
- M. I. Ragone
- Cátedra de Farmacología, Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas; Universidad Nacional de La Plata (UNLP); La Plata; Argentina
| | - N. S. Torres
- The Nora Eccles Harrison Cardiovascular Research and Training Institute (CVRTI); Salt Lake City; UT; USA
| | - A. E. Consolini
- Cátedra de Farmacología, Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas; Universidad Nacional de La Plata (UNLP); La Plata; Argentina
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Rosa AO, Yamaguchi N, Morad M. Mechanical regulation of native and the recombinant calcium channel. Cell Calcium 2013; 53:264-74. [PMID: 23357406 DOI: 10.1016/j.ceca.2012.12.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2012] [Accepted: 12/25/2012] [Indexed: 11/30/2022]
Abstract
L-type calcium channels are modulated by a host of mechanisms that include voltage, calcium ions (Ca(2+) dependent inactivation and facilitation), cytosolic proteins (CAM, CAMKII, PKA, PKC, etc.), and oxygen radicals. Here we describe yet another Ca(2+) channel regulatory mechanism that is induced by pressure-flow (PF) forces of ∼25dyn/cm(2) producing 35-60% inhibition of channel current. Only brief periods (300ms) of such PF pulses were required to suppress reversibly the current. Recombinant Ca(2+) channels (α1c77/β2a/α2δ and α1c77/β1/α2δ), expressed in HEK293 cells, were similarly suppressed by PF pulses. To examine whether Ca(2+) released by PF pulses triggered from different sub-cellular compartments (SR, ER, mitochondria) underlies the inhibitory effect of PF on the channel current, pharmacological agents and ionic substitutions were employed to probe this possibility. No significant difference in effectiveness of PF pulses to suppress ICa or IBa (used to inhibit CICR) was found between control cells and those exposed to U73122 and 2-APB (PLC and IP3R pathway modulators), thapsigargin and BAPTA (SERCA2a modulator), dinitrophenol, FCCP and Ru360 (mitochondrial inhibitors), l-NAME (NOS inhibitor signaling), cAMP and Pertussis toxin (Gi protein modulator). We concluded that the rapid and reversible modulation of the Ca(2+) channel by PF pulses is independent of intracellular release of Ca(2+) and Ca(2+) dependent inactivation of the channel and may represent direct mechanical regulatory effect on the channel protein in addition to previously reported Ca(2+)-release or entry dependent mechanism.
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Affiliation(s)
- Angelo O Rosa
- Cardiac Signaling Center, University of South Carolina, Charleston, SC 29425, USA
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20
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The mitochondrial Na+/Ca2+ exchanger upregulates glucose dependent Ca2+ signalling linked to insulin secretion. PLoS One 2012; 7:e46649. [PMID: 23056385 PMCID: PMC3466326 DOI: 10.1371/journal.pone.0046649] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2012] [Accepted: 09/03/2012] [Indexed: 11/25/2022] Open
Abstract
Mitochondria mediate dual metabolic and Ca2+ shuttling activities. While the former is required for Ca2+ signalling linked to insulin secretion, the role of the latter in β cell function has not been well understood, primarily because the molecular identity of the mitochondrial Ca2+ transporters were elusive and the selectivity of their inhibitors was questionable. This study focuses on NCLX, the recently discovered mitochondrial Na+/Ca2+ exchanger that is linked to Ca2+ signalling in MIN6 and primary β cells. Suppression either of NCLX expression, using a siRNA construct (siNCLX) or of its activity, by a dominant negative construct (dnNCLX), enhanced mitochondrial Ca2+ influx and blocked efflux induced by glucose or by cell depolarization. In addition, NCLX regulated basal, but not glucose-dependent changes, in metabolic rate, mitochondrial membrane potential and mitochondrial resting Ca2+. Importantly, NCLX controlled the rate and amplitude of cytosolic Ca2+ changes induced by depolarization or high glucose, indicating that NCLX is a critical and rate limiting component in the cross talk between mitochondrial and plasma membrane Ca2+ signalling. Finally, knockdown of NCLX expression was followed by a delay in glucose-dependent insulin secretion. These findings suggest that the mitochondrial Na+/Ca2+ exchanger, NCLX, shapes glucose-dependent mitochondrial and cytosolic Ca2+ signals thereby regulating the temporal pattern of insulin secretion in β cells.
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21
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Pizzo P, Drago I, Filadi R, Pozzan T. Mitochondrial Ca²⁺ homeostasis: mechanism, role, and tissue specificities. Pflugers Arch 2012; 464:3-17. [PMID: 22706634 DOI: 10.1007/s00424-012-1122-y] [Citation(s) in RCA: 116] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2012] [Accepted: 05/29/2012] [Indexed: 12/18/2022]
Abstract
Mitochondria from every tissue are quite similar in their capability to accumulate Ca²⁺ in a process that depends on the electrical potential across the inner membrane; it is catalyzed by a gated channel (named mitochondrial Ca²⁺ uniporter), the molecular identity of which has only recently been unraveled. The release of accumulated Ca²⁺ in mitochondria from different tissues is, on the contrary, quite variable, both in terms of speed and mechanism: a Na⁺-dependent efflux in excitable cells (catalyzed by NCLX) and a H⁺/Ca²⁺ exchanger in other cells. The efficacy of mitochondrial Ca²⁺ uptake in living cells is strictly dependent on the topological arrangement of the organelles with respect to the source of Ca²⁺ flowing into the cytoplasm, i.e., plasma membrane or intracellular channels. In turn, the structural and functional relationships between mitochondria and other cellular membranes are dictated by the specific architecture of different cells. Mitochondria not only modulate the amplitude and the kinetics of local and bulk cytoplasmic Ca²⁺ changes but also depend on the Ca²⁺ signal for their own functionality, in particular for their capacity to produce ATP. In this review, we summarize the processes involved in mitochondrial Ca²⁺ handling and its integration in cell physiology, highlighting the main common characteristics as well as key differences, in different tissues.
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Affiliation(s)
- Paola Pizzo
- Department of Biomedical Sciences, University of Padua, Padua, Italy
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22
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Yaniv Y, Spurgeon HA, Lyashkov AE, Yang D, Ziman BD, Maltsev VA, Lakatta EG. Crosstalk between mitochondrial and sarcoplasmic reticulum Ca2+ cycling modulates cardiac pacemaker cell automaticity. PLoS One 2012; 7:e37582. [PMID: 22666369 PMCID: PMC3362629 DOI: 10.1371/journal.pone.0037582] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2012] [Accepted: 04/22/2012] [Indexed: 01/02/2023] Open
Abstract
Background Mitochondria dynamically buffer cytosolic Ca2+ in cardiac ventricular cells and this affects the Ca2+ load of the sarcoplasmic reticulum (SR). In sinoatrial-node cells (SANC) the SR generates periodic local, subsarcolemmal Ca2+ releases (LCRs) that depend upon the SR load and are involved in SANC automaticity: LCRs activate an inward Na+-Ca2+ exchange current to accelerate the diastolic depolarization, prompting the ensemble of surface membrane ion channels to generate the next action potential (AP). Objective To determine if mitochondrial Ca2+ (Ca2+m), cytosolic Ca2+ (Ca2+c)-SR-Ca2+ crosstalk occurs in single rabbit SANC, and how this may relate to SANC normal automaticity. Results Inhibition of mitochondrial Ca2+ influx into (Ru360) or Ca2+ efflux from (CGP-37157) decreased [Ca2+]m to 80±8% control or increased [Ca2+]m to 119±7% control, respectively. Concurrent with inhibition of mitochondrial Ca2+ influx or efflux, the SR Ca2+ load, and LCR size, duration, amplitude and period (imaged via confocal linescan) significantly increased or decreased, respectively. Changes in total ensemble LCR Ca2+ signal were highly correlated with the change in the SR Ca2+ load (r2 = 0.97). Changes in the spontaneous AP cycle length (Ru360, 111±1% control; CGP-37157, 89±2% control) in response to changes in [Ca2+]m were predicted by concurrent changes in LCR period (r2 = 0.84). Conclusion A change in SANC Ca2+m flux translates into a change in the AP firing rate by effecting changes in Ca2+c and SR Ca2+ loading, which affects the characteristics of spontaneous SR Ca2+ release.
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Affiliation(s)
- Yael Yaniv
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, United States of America
| | - Harold A. Spurgeon
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, United States of America
| | - Alexey E. Lyashkov
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, United States of America
| | - Dongmei Yang
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, United States of America
| | - Bruce D. Ziman
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, United States of America
| | - Victor A. Maltsev
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, United States of America
| | - Edward G. Lakatta
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, United States of America
- * E-mail:
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Rodriguez P, Satorre M, Beconi M. Effect of two intracellular calcium modulators on sperm motility and heparin-induced capacitation in cryopreserved bovine spermatozoa. Anim Reprod Sci 2012; 131:135-42. [DOI: 10.1016/j.anireprosci.2012.03.015] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2011] [Revised: 03/21/2012] [Accepted: 03/25/2012] [Indexed: 11/26/2022]
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Haojun Z, Yaoling W, Ke Z, Jin L, Junling W. Effects of NaF on the expression of intracellular Ca2+ fluxes and apoptosis and the antagonism of taurine in murine neuron. Toxicol Mech Methods 2012; 22:305-8. [PMID: 22356551 DOI: 10.3109/15376516.2012.657259] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Sodium fluoride (NaF) has been shown to be cytotoxic and produces inflammatory responses in humans. However, the cellular mechanisms underlying the neurotoxicity of fluoride are unclear. The present study aims to define a possible mechanism of NaF-induced neurotoxicity with respect to apoptosis and intracellular Ca(2+) fluxes. Meanwhile, the cytoprotective role of taurine in intervention, the toxic effects of NaF on neurons, is also investigated. The primary mouse hippocampal neurons were incubated with 5.0, 10.0, 15.0, 20.0, and 40.0 mg NaF/L in vitro and Kunming mice were exposed to 0.7, 2.8, and 11.2 mg NaF/kg and 7.5 and 15.0 mg taurine/kg in vivo. Intracellular Ca(2+) fluxes and apoptosis were assayed. Compared with the control, the significant differences of intracellular Ca(2+) concentration and apoptotic peaks were found in 5.0-40.0 mg NaF/L groups in vitro (p < 0.01) and in the groups of 0.7-11.2 mg NaF/kg in vivo (p < 0.01). Instantaneously, taurine can minimize F-induced neurotoxicity significantly at doses of 7.5 and 15.0 mg/kg (p < 0.01). The present study herein suggested that NaF could increase intercellular Ca(2+) concentration leading to apoptosis. Meanwhile, taurine could minimize neurotoxicity caused by fluoride through decreasing intercellular Ca(2+) concentration and cell apoptosis.
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Affiliation(s)
- Zhang Haojun
- People's Hospital of Gansu Province, Lanzhou, China
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25
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Pandit MM, Strait KA, Matsuda T, Kohan DE. Na delivery and ENaC mediate flow regulation of collecting duct endothelin-1 production. Am J Physiol Renal Physiol 2012; 302:F1325-30. [PMID: 22357920 DOI: 10.1152/ajprenal.00034.2012] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Collecting duct (CD) endothelin-1 (ET-1) is an important autocrine inhibitor of Na and water transport. CD ET-1 production is stimulated by extracellular fluid volume expansion and tubule fluid flow, suggesting a mechanism coupling CD Na delivery and ET-1 synthesis. A mouse cortical CD cell line, mpkCCDc14, was subjected to static or flow conditions for 2 h at 2 dyn/cm(2), followed by determination of ET-1 mRNA content. Flow with 300 mosmol/l NaCl increased ET-1 mRNA to 65% above that observed under static conditions. Increasing perfusate osmolarity to 450 mosmol/l with NaCl or Na acetate increased ET-1 mRNA to ∼184% compared with no flow, which was not observed when osmolarity was increased using mannitol or urea. Reducing Na concentration to 150 mosmol/l while maintaining total osmolarity at 300 mosmol/l with urea or mannitol decreased the flow response. Inhibition of epithelial Na channel (ENaC) with amiloride or benzamil abolished the flow response, suggesting involvement of ENaC in flow-regulated ET-1 synthesis. Aldosterone almost doubled the flow response. Since Ca(2+) enhances CD ET-1 production, the involvement of plasma membrane and mitochondrial Na/Ca(2+) exchangers (NCX) was assessed. SEA0400 and KB-R7943, plasma membrane NCX inhibitors, did not affect the flow response. However, CGP37157, a mitochondrial NCX inhibitor, abolished the response. In summary, the current study indicates that increased Na delivery, leading to ENaC-mediated Na entry and mitochondrial NCX activity, is involved in flow-stimulated CD ET-1 synthesis. This constitutes the first report of either ENaC or mitochondrial NCX regulation of an autocrine factor in any biologic system.
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Affiliation(s)
- Meghana M Pandit
- Division of Nephrology, University of Utah Health Sciences Center, 1900 East, 30 North, Salt Lake City, UT 84132, USA
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26
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Kim B, Takeuchi A, Koga O, Hikida M, Matsuoka S. Pivotal role of mitochondrial Na⁺₋Ca²⁺ exchange in antigen receptor mediated Ca²⁺ signalling in DT40 and A20 B lymphocytes. J Physiol 2011; 590:459-74. [PMID: 22155933 DOI: 10.1113/jphysiol.2011.222927] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Cytoplasmic Ca(2+) concentration ([Ca(2+)](i)) increases upon activation of antigen-receptor in lymphocytes. Mitochondria have been suggested to regulate the [Ca(2+)](i) response, but the molecular mechanisms and the roles are poorly understood. To clarify them, we carried out a combination study of mathematical simulations and knockout or knockdown of NCLX, a gene candidate for the mitochondrial Na(+)-Ca(2+) exchanger (NCX(mit)), in B lymphocytes. A mathematical model of Ca(2+) dynamics in B lymphocytes demonstrated that NCX(mit) inhibition reduces basal Ca(2+) content of endoplasmic reticulum (ER) and suppresses B-cell antigen receptor (BCR)-mediated [Ca(2+)](i) rise. The predictions were validated in DT40 B lymphocytes of heterozygous NCLX knockout (NCLX(+/-)). In NCLX(+/-) cells, mitochondrial Ca(2+) efflux via NCX(mit) was strongly decelerated, suggesting NCLX is a gene responsible for NCX(mit) in B lymphocytes. Consistent with the predictions, ER Ca(2+) content declined and [Ca(2+)](i) hardly rose upon BCR activation in NCLX(+/-) cells. ER Ca(2+) uptake was reduced to ∼58% of the wild-type (WT), while it was comparable to WT when mitochondrial respiration was disturbed. Essentially the same results were obtained by a pharmacological inhibition or knockdown of NCLX by siRNA in A20 B lymphocytes. Unexpectedly, ER Ca(2+) leak was augmented and co-localization of mitochondria with ER was lower in NCLX(+/-) and NCLX silenced cells. Taken together, we concluded that NCLX is a key Ca(2+) provider to ER, and that NCLX-mediated Ca(2+) recycling between mitochondria and ER is pivotal in B cell responses to antigen.
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Affiliation(s)
- Bongju Kim
- Center for Innovation in Immunoregulative Technology and Therapeutics, Kyoto University, Yoshida-konoe, Sakyo-ku, Kyoto 606-8501, Japan
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Kobayashi K, Enmi Y, Iitsuka D, Kanbe Y, Konishi H. Synthesis of 1,2,3,5-Tetrahydro-4,1-benzothiazepine-2-thione Derivatives via Cyclization of 2-[(2-Isothiocyanatophenyl)methylsulfanyl]acetates with Sodium Hydride. HETEROCYCLES 2011. [DOI: 10.3987/com-11-12283] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Neumann JT, Diaz-Sylvester PL, Fleischer S, Copello JA. CGP-37157 inhibits the sarcoplasmic reticulum Ca²+ ATPase and activates ryanodine receptor channels in striated muscle. Mol Pharmacol 2010; 79:141-7. [PMID: 20923851 DOI: 10.1124/mol.110.067165] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
7-Chloro-5-(2-chlorophenyl)-1,5-dihydro-4,1-benzothiazepin-2(3H)-one [CGP-37157 (CGP)], a benzothiazepine derivative of clonazepam, is commonly used as a blocker of the mitochondrial Na+/Ca²+ exchanger. However, evidence suggests that CGP could also affect other targets, such as L-type Ca²+ channels and plasmalemma Na+/Ca²+ exchanger. Here, we tested the possibility of a direct modulation of ryanodine receptor channels (RyRs) and/or sarco/endoplasmic reticulum Ca²+-stimulated ATPase (SERCA) by CGP. In the presence of ruthenium red (inhibitor of RyRs), CGP decreased SERCA-mediated Ca²+ uptake of cardiac and skeletal sarcoplasmic reticulum (SR) microsomes (IC₅₀ values of 6.6 and 9.9 μM, respectively). The CGP effects on SERCA activity correlated with a decreased V(max) of ATPase activity of SERCA-enriched skeletal SR fractions. CGP (≥ 5 μM) also increased RyR-mediated Ca²+ leak from skeletal SR microsomes. Planar bilayer studies confirmed that both cardiac and skeletal RyRs are directly activated by CGP (EC(50) values of 9.4 and 12.0 μM, respectively). In summary, we found that CGP inhibits SERCA and activates RyR channels. Hence, the action of CGP on cellular Ca²+ homeostasis reported in the literature of cardiac, skeletal muscle, and other nonmuscle systems requires further analysis to take into account the contribution of all CGP-sensitive Ca²+ transporters.
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Affiliation(s)
- Jake T Neumann
- Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, Illinois, USA
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Atrial local Ca2+ signaling and inositol 1,4,5-trisphosphate receptors. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2010; 103:59-70. [DOI: 10.1016/j.pbiomolbio.2010.02.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2009] [Revised: 01/18/2010] [Accepted: 02/18/2010] [Indexed: 11/24/2022]
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30
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Mitochondrial Na+/Ca2+ exchanger, a new target for neuroprotection in rat hippocampal slices. Biochem Biophys Res Commun 2010; 400:140-4. [DOI: 10.1016/j.bbrc.2010.08.028] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2010] [Accepted: 08/07/2010] [Indexed: 12/17/2022]
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31
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Shiba SA, El-Ziaty AK, El-Aasar NK, Al-Saman HA. Reaction of (E)-3-(Benzo[d][1,3]dioxol-5-yl)-2- Cyanoacryloyl Chloride with Nucleophilic Reagents Containing Nitrogen and Sulfur. PHOSPHORUS SULFUR 2010. [DOI: 10.1080/10426500903176547] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Affiliation(s)
- S. A. Shiba
- a Chemistry Department, Faculty of Science , Ain Shams University , Cairo, Egypt
| | - A. K. El-Ziaty
- a Chemistry Department, Faculty of Science , Ain Shams University , Cairo, Egypt
| | - N. K. El-Aasar
- a Chemistry Department, Faculty of Science , Ain Shams University , Cairo, Egypt
| | - H. A. Al-Saman
- a Chemistry Department, Faculty of Science , Ain Shams University , Cairo, Egypt
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Feldman B, Fedida-Metula S, Nita J, Sekler I, Fishman D. Coupling of mitochondria to store-operated Ca(2+)-signaling sustains constitutive activation of protein kinase B/Akt and augments survival of malignant melanoma cells. Cell Calcium 2010; 47:525-37. [PMID: 20605628 DOI: 10.1016/j.ceca.2010.05.002] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2009] [Revised: 05/04/2010] [Accepted: 05/06/2010] [Indexed: 11/29/2022]
Abstract
Mitochondria are emerging as a major hub for cellular Ca(2+)-signaling, though their contribution to Ca(2+)-driven growth- and survival-promoting events in cancer is poorly understood. Here employing flow cytometry to monitor mitochondrial and cytosolic Ca(2+), we assessed trans-mitochondrial Ca(2+)-transport and store-operated Ca(2+)-influx (store-operated channels (SOC)) in malignant vs. non-malignant B16BL6 melanoma clones. Remarkably, mitochondrial Ca(2+)-fluxes measured in whole cells or in isolated mitochondria were accelerated in the malignant clones compared to their non-malignant counterpart clones. This coincided with enhanced SOC-mediated Ca(2+)-influx and high levels of constitutively active protein kinase B/Akt (PKB). Interruption of trans-mitochondrial Ca(2+)-transport in the malignant cells with an antagonist of the mitochondrial Na(+)/Ca(2+) exchanger, CGP-37157, abolsihed SOC-mediated Ca(2+)-influx, inactivated PKB, retarded cell growth and increased vulnerability to apoptosis. Similarly, direct SOC blockade by silencing Stim1 inhibited PKB, indicating that the crosstalk between SOC and mitochondria is essential to preserve PKB in constitutively active state. Finally, the retraction of mitochondria from sub-plasmalemmal micro-domains triggered by Fis1 over-expression inhibited SOC-coupled trans-mitochondrial Ca(2+)-flux, Ca(2+)-entry via SOC and PKB activity. Taken together, our data show that in the malignant melanoma cells, the functional and spatial relationship of up-regulated mitochondrial Ca(2+)-transport to the SOC sustains the robust Ca(2+)-responses and down-stream signaling critical for apoptosis-resistance and proliferation.
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Affiliation(s)
- Ben Feldman
- Department of Morphology, Ben-Gurion University Cancer Research Center, Ben-Gurion University of the Negev, Beer-Sheva, Israel
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Chalmers S, McCarron JG. Inhibition of mitochondrial calcium uptake rather than efflux impedes calcium release by inositol-1,4,5-trisphosphate-sensitive receptors. Cell Calcium 2009; 46:107-13. [PMID: 19577805 DOI: 10.1016/j.ceca.2009.05.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2008] [Revised: 05/07/2009] [Accepted: 05/31/2009] [Indexed: 10/20/2022]
Abstract
Mitochondria modulate cellular Ca2+ signals by accumulating the ion via a uniporter and releasing it via Na+- or H+-exchange. In smooth muscle, inhibition of mitochondrial Ca2+ uptake inhibits Ca2+ release from the sarcoplasmic reticulum (SR) via inositol-1,4,5-trisphosphate-sensitive receptors (IP(3)R). At least two mechanisms may explain this effect. First, localised uptake of Ca2+ by mitochondria may prevent negative feedback by cytosolic Ca2+ on IP(3)R activity, or secondly localised provision of Ca2+ by mitochondrial efflux may maintain IP(3)R function or SR Ca2+ content. To distinguish between these possibilities the role of mitochondrial Ca2+ efflux on IP(3)R function was examined. IP(3) was liberated in freshly isolated single colonic smooth muscle cells and mitochondrial Na+-Ca2+ exchanger inhibited with CGP-37157 (10microM). Mitochondria accumulated Ca2+ during IP(3)-evoked [Ca2+](c) rises and released the ion back to the cytosol (within approximately 15s) when mitochondrial Ca2+ efflux was active. When mitochondrial Ca2+ efflux was inhibited by CGP-37157, an extensive and sustained loading of mitochondria with Ca2+ occurred after IP(3)-evoked Ca2+ release. IP(3)-evoked [Ca2+](c) rises were initially unaffected, then only slowly inhibited by CGP-37157. IP(3)R activity was required for inhibition to occur; incubation with CGP-37157 for the same duration without IP(3) release did not inhibit IP(3)R. CGP-37157 directly inhibited voltage-gated Ca2+ channel activity, however SR Ca2+ content was unaltered by the drug. Thus, the gradual decline of IP(3)R function that followed mitochondrial Na+-Ca2+ exchanger inhibition resulted from a gradual overload of mitochondria with Ca2+, leading to a reduced capacity for Ca2+ uptake. Localised uptake of Ca2+ by mitochondria, rather than mitochondrial Ca2+ efflux, appears critical for maintaining IP(3)R activity.
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Affiliation(s)
- Susan Chalmers
- Strathclyde Institute of Pharmacy & Biomedical Sciences, University of Strathclyde, John Arbuthnott Building, 27 Taylor Street, Glasgow G4 0NR, UK
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Dofetilide Enhances the Contractility of Rat Ventricular Myocytes via Augmentation of Na+–Ca2+ Exchange. Cardiovasc Drugs Ther 2009; 23:207-14. [DOI: 10.1007/s10557-009-6163-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/12/2008] [Accepted: 01/19/2009] [Indexed: 10/21/2022]
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Demaurex N, Poburko D, Frieden M. Regulation of plasma membrane calcium fluxes by mitochondria. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2009; 1787:1383-94. [PMID: 19161976 DOI: 10.1016/j.bbabio.2008.12.012] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2008] [Revised: 12/21/2008] [Accepted: 12/29/2008] [Indexed: 11/27/2022]
Abstract
The role of mitochondria in cell signaling is becoming increasingly apparent, to an extent that the signaling role of mitochondria appears to have stolen the spotlight from their primary function as energy producers. In this chapter, we will review the ionic basis of calcium handling by mitochondria and discuss the mechanisms that these organelles use to regulate the activity of plasma membrane calcium channels and transporters.
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Affiliation(s)
- Nicolas Demaurex
- Department of Cell Physiology and Metabolism, University of Geneva, 1, rue Michel-Servet, CH-1211 Geneva 4, Switzerland
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36
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Montoya G JV, Sutachan JJ, Corrales A, Xu F, Blanck TJJ, Recio-Pinto E. Pulses of extracellular K+ produce two cytosolic Ca2+ transients that display different temperature dependence and carbonyl cyanide m-chlorophenyl sensitivity in SH-SY5Y cells. Brain Res 2008; 1213:12-26. [PMID: 18448083 DOI: 10.1016/j.brainres.2008.03.022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2007] [Revised: 01/23/2008] [Accepted: 03/07/2008] [Indexed: 10/22/2022]
Abstract
In SH-SY5Y cells we have shown that stimulation with high extracellular K+ ([K+]e) evokes a transient increase in cytoplasmic Ca2+ ([Ca2+]cyt) (K+on) that is triggered by the opening of voltage-dependent Ca2+ channels and followed by Ca2+ -induced Ca2+ release from the endoplasmic reticulum (Xu, F., Zhang, J., Recio-Pinto, E. and Blanck, T.J., Halothane and isoflurane augment depolarization-induced cytosolic CA2+ transients and attenuate carbachol-stimulated CA2+ transients, Anesthesiology, 92 (2000) 1746-56). The removal of high-[K+]e results in a second transient increase in [Ca2+]cyt (K+off) that is independent of extracellular Ca2+ (Corrales, A., Montoya, G.J., Sutachan, J.J., Cornillez-Ty, G., Garavito-Aguilar, Z., Xu, F., Blanck, T.J. and Recio-Pinto, E., Transient increases in extracellular K+ produce two pharmacological distinct cytosolic Ca2+ transients, Brain Res., 1031 (2005) 174-184). In this study we further characterize the properties of K+off. We found that K+off was detectable at near physiological temperatures (34-36 degrees C) but, depending on the level of [K+]e, it was undetectable or highly diminished at room temperature. In contrast, K+on was increased by lowering the temperature. Extracellular Na+ -replacement with K+ did not affect K+off, indicating that K+off was not generated by osmolarity changes. Replacement of extracellular Na+ with choline+ did not affect K+off, indicating that K+off did not result from activity changes of the plasma membrane Na+/Ca2+ exchanger. Caffeine decreased K+on but not K+off. CCCP (carbonyl cyanide m-chlorophenyl), a protonophore uncoupler that decreases mitochondrial Ca2+ uptake, decreased K+on but not K+off. CGP37157, an inhibitor of the mitochondria Na+/Ca2+ exchanger, decreased K+off when added alone but not when added simultaneously with CCCP. Clonazepam had similar effects as CGP37157. These findings indicate that the generation of K+off is strongly temperature-dependent and its pharmacology is distinct from the [Ca2+]cyt changes observed previously at room temperature.
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Affiliation(s)
- José V Montoya G
- Anesthesiology Department, New York University Medical Center, New York, NY 10016, USA
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Luciani DS, Ao P, Hu X, Warnock GL, Johnson JD. Voltage-gated Ca2+ influx and insulin secretion in human and mouse β-cells are impaired by the mitochondrial Na+/Ca2+ exchange inhibitor CGP-37157. Eur J Pharmacol 2007; 576:18-25. [PMID: 17719029 DOI: 10.1016/j.ejphar.2007.07.055] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2007] [Revised: 07/25/2007] [Accepted: 07/26/2007] [Indexed: 11/20/2022]
Abstract
Glucose-induced insulin release from pancreatic beta-cells relies largely on glucose metabolism and mitochondrial ATP synthesis. Inhibiting the mitochondrial Na(+)/Ca(2+) exchanger (mNCE) using 7-Chloro-5-(2-chlorophenyl)-1,5-dihydro-4,1-benzothiazepin-2(3H)-one (CGP-37157) has been suggested to enhance ATP synthesis and insulin secretion from rat islets by promoting mitochondrial Ca(2+) accumulation. In this study we examined the effects of CGP-37157 on human and mouse islet cells. Surprisingly, we found that insulin secretion from perifused islets was reduced by CGP-37157. Cytosolic Ca(2+) measurements revealed that CGP-37157 dose-dependently blocked glucose- and KCl-stimulated Ca(2+) signals in both human and mouse beta-cells. Conversely, CGP-37157 induced mitochondrial hyperpolarization, NAD(P)H rises, and triggered diazoxide- and nifedipine-sensitive cytosolic Ca(2+) transients in a subset of quiescent cells bathed in sub-stimulatory glucose, which is in accord with metabolic activation by the compound. Hence, while blocking mNCE with CGP-37157 may augment metabolism of human and mouse beta-cells, the propagation of metabolic signals is hampered by simultaneous inhibition of voltage-gated Ca(2+) influx, and ultimately insulin secretion. Efforts to use CGP-37157 or design related compounds for therapeutic purposes should take these competing effects into account.
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Affiliation(s)
- Dan S Luciani
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, BC, Canada
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Luccini E, Raiteri L. Mechanisms of [3H]glycine release from mouse spinal cord synaptosomes selectively labeled through GLYT2 transporters. J Neurochem 2007; 103:2439-48. [DOI: 10.1111/j.1471-4159.2007.04967.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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