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Sheng CQ, Wu SS, Cheng YK, Wu Y, Li YM. Comprehensive review of indicators and techniques for optical mapping of intracellular calcium ions. Cereb Cortex 2024; 34:bhae346. [PMID: 39191664 DOI: 10.1093/cercor/bhae346] [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: 05/01/2024] [Revised: 07/27/2024] [Accepted: 08/09/2024] [Indexed: 08/29/2024] Open
Abstract
Calcium ions (Ca2+) play crucial roles in almost every cellular process, making the detection of changes in intracellular Ca2+ essential to understanding cell function. The fluorescence indicator method has garnered widespread application due to its exceptional sensitivity, rapid analysis, cost-effectiveness, and user-friendly nature. It has successfully delineated the spatial and temporal dynamics of Ca2+ signaling across diverse cell types. However, it is vital to understand that different indicators have varying levels of accuracy, sensitivity, and stability, making choosing the right inspection method crucial. As optical detection technologies advance, they continually broaden the horizons of scientific inquiry. This primer offers a systematic synthesis of the current fluorescence indicators and optical imaging modalities utilized for the detection of intracellular Ca2+. It elucidates their practical applications and inherent limitations, serving as an essential reference for researchers seeking to identify the most suitable detection methodologies for their calcium-centric investigations.
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Affiliation(s)
- Chu-Qiao Sheng
- Department of Pediatric Intensive Care Unit, Children's Medical Center, The First Hospital of Jilin University, Changchun, Jilin 130021, China
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, No. 2699, Qianjin Street, Changchun, Jilin 130012, China
| | - Shuang-Shuang Wu
- Department of Pediatric Hematology, Children's Medical Center, The First Hospital of Jilin University, Changchun, Jilin 130021, China
| | - Yong-Kang Cheng
- Department of Pediatric Intensive Care Unit, Children's Medical Center, The First Hospital of Jilin University, Changchun, Jilin 130021, China
| | - Yao Wu
- Department of Pediatric Intensive Care Unit, Children's Medical Center, The First Hospital of Jilin University, Changchun, Jilin 130021, China
| | - Yu-Mei Li
- Department of Pediatric Intensive Care Unit, Children's Medical Center, The First Hospital of Jilin University, Changchun, Jilin 130021, China
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Gherardi G, De Mario A, Mammucari C. The mitochondrial calcium homeostasis orchestra plays its symphony: Skeletal muscle is the guest of honor. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2021; 362:209-259. [PMID: 34253296 DOI: 10.1016/bs.ircmb.2021.03.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/03/2023]
Abstract
Skeletal muscle mitochondria are placed in close proximity of the sarcoplasmic reticulum (SR), the main intracellular Ca2+ store. During muscle activity, excitation of sarcolemma and of T-tubule triggers the release of Ca2+ from the SR initiating myofiber contraction. The rise in cytosolic Ca2+ determines the opening of the mitochondrial calcium uniporter (MCU), the highly selective channel of the inner mitochondrial membrane (IMM), causing a robust increase in mitochondrial Ca2+ uptake. The Ca2+-dependent activation of TCA cycle enzymes increases the synthesis of ATP required for SERCA activity. Thus, Ca2+ is transported back into the SR and cytosolic [Ca2+] returns to resting levels eventually leading to muscle relaxation. In recent years, thanks to the molecular identification of MCU complex components, the role of mitochondrial Ca2+ uptake in the pathophysiology of skeletal muscle has been uncovered. In this chapter, we will introduce the reader to a general overview of mitochondrial Ca2+ accumulation. We will tackle the key molecular players and the cellular and pathophysiological consequences of mitochondrial Ca2+ dyshomeostasis. In the second part of the chapter, we will discuss novel findings on the physiological role of mitochondrial Ca2+ uptake in skeletal muscle. Finally, we will examine the involvement of mitochondrial Ca2+ signaling in muscle diseases.
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Affiliation(s)
- Gaia Gherardi
- Department of Biomedical Sciences, University of Padua, Padua, Italy
| | - Agnese De Mario
- Department of Biomedical Sciences, University of Padua, Padua, Italy
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Ding Y, Ling J, Qiao Y, Li Z, Sun Z, Cai J, Guo Y, Wang H. A high-throughput fluorimetric microarray with enhanced fluorescence and suppressed "coffee-ring" effects for the detection of calcium ions in blood. Sci Rep 2016; 6:38602. [PMID: 27917959 PMCID: PMC5137002 DOI: 10.1038/srep38602] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Accepted: 11/09/2016] [Indexed: 01/29/2023] Open
Abstract
A rapid, ultrasensitive, and high-throughput fluorimetric microarray method has been developed using hydrophobic pattern as the microarray substrate and 3-aminopropyltriethoxysilane-coupled carboxylic acid calcium (APS-CCA) as the fluorescent probes for sensing Ca2+ ions in blood. The hydrophobic pattern of the developed Ca2+ analysis microarray could largely suppress the "coffee-ring" effects to facilitate the better distribution density of testing microspots toward the high-throughput detections, and especially prevent the cross-contamination of the multiple samples between adjacent microspots. Moreover, the use of APS matrix could endow the CCA probe the enhanced environmental stability and fluorescence intensity, which is about 2.3-fold higher than that of free CCA. The interactions between APS-CCA and Ca2+ ions were systematically characterized by UV-vis and fluorescence measurements including microscopy imaging. It was demonstrated that the fluorimetric microarray could display the strong capacity of specifically sensing Ca2+ ions with the minimal interferences from blood backgrounds. Such an APS-CCA-based fluorimetric microarray can allow for the analysis of Ca2+ ions down to 0.0050 mM in blood, promising a highly sensitive and selective detection candidate for Ca2+ ions to be applied in the clinical laboratory.
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Affiliation(s)
- Yanjun Ding
- Department of Forensic Science, School of Basic Medical Sciences, Central South University, Changsha 410013, Hunan, China
| | - Jiang Ling
- Department of Forensic Science, School of Basic Medical Sciences, Central South University, Changsha 410013, Hunan, China
- College of Chemistry and Chemical Engineering, Qufu Normal University, Qufu 273165, P. R. China
| | - Yuchun Qiao
- College of Chemistry and Chemical Engineering, Qufu Normal University, Qufu 273165, P. R. China
| | - Zhengjian Li
- College of Chemistry and Chemical Engineering, Qufu Normal University, Qufu 273165, P. R. China
| | - Zongzhao Sun
- College of Chemistry and Chemical Engineering, Qufu Normal University, Qufu 273165, P. R. China
| | - Jifeng Cai
- Department of Forensic Science, School of Basic Medical Sciences, Central South University, Changsha 410013, Hunan, China
| | - Yadong Guo
- Department of Forensic Science, School of Basic Medical Sciences, Central South University, Changsha 410013, Hunan, China
| | - Hua Wang
- College of Chemistry and Chemical Engineering, Qufu Normal University, Qufu 273165, P. R. China
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Muslikhov ER, Sukhanova IF, Avdonin PV. Arachidonic acid activates release of calcium ions from reticulum via ryanodine receptor channels in C2C12 skeletal myotubes. BIOCHEMISTRY (MOSCOW) 2015; 79:435-9. [PMID: 24954594 DOI: 10.1134/s0006297914050071] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Arachidonic acid causes an increase in free cytoplasmic calcium concentration ([Ca2+]i) in differentiated skeletal multinucleated myotubes C2C12 and does not induce calcium response in C2C12 myoblasts. The same reaction of myotubes to arachidonic acid is observed in Ca2+-free medium. This indicates that arachidonic acid induces release of calcium ions from intracellular stores. The blocker of ryanodine receptor channels of sarcoplasmic reticulum dantrolene (20 µM) inhibits this effect by 68.7 ± 6.3% (p < 0.001). The inhibitor of two-pore calcium channels of endolysosomal vesicles trans-NED19 (10 µM) decreases the response to arachidonic acid by 35.8 ± 5.4% (p < 0.05). The phospholipase C inhibitor U73122 (10 µM) has no effect. These data indicate the involvement of ryanodine receptor calcium channels of sarcoplasmic reticulum in [Ca2+]i elevation in skeletal myotubes caused by arachidonic acid and possible participation of two-pore calcium channels from endolysosomal vesicles in this process.
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Affiliation(s)
- E R Muslikhov
- Koltsov Institute of Developmental Biology, Russian Academy of Sciences, Moscow, 119334, Russia.
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Langone F, Cannata S, Fuoco C, Lettieri Barbato D, Testa S, Nardozza AP, Ciriolo MR, Castagnoli L, Gargioli C, Cesareni G. Metformin protects skeletal muscle from cardiotoxin induced degeneration. PLoS One 2014; 9:e114018. [PMID: 25461598 PMCID: PMC4252070 DOI: 10.1371/journal.pone.0114018] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2014] [Accepted: 11/04/2014] [Indexed: 11/18/2022] Open
Abstract
The skeletal muscle tissue has a remarkable capacity to regenerate upon injury. Recent studies have suggested that this regenerative process is improved when AMPK is activated. In the muscle of young and old mice a low calorie diet, which activates AMPK, markedly enhances muscle regeneration. Remarkably, intraperitoneal injection of AICAR, an AMPK agonist, improves the structural integrity of muscles of dystrophin-deficient mdx mice. Building on these observations we asked whether metformin, a powerful anti-hyperglycemic drug, which indirectly activates AMPK, affects the response of skeletal muscle to damage. In our conditions, metformin treatment did not significantly influence muscle regeneration. On the other hand we observed that the muscles of metformin treated mice are more resilient to cardiotoxin injury displaying lesser muscle damage. Accordingly myotubes, originated in vitro from differentiated C2C12 myoblast cell line, become more resistant to cardiotoxin damage after pre-incubation with metformin. Our results indicate that metformin limits cardiotoxin damage by protecting myotubes from necrosis. Although the details of the molecular mechanisms underlying the protective effect remain to be elucidated, we report a correlation between the ability of metformin to promote resistance to damage and its capacity to counteract the increment of intracellular calcium levels induced by cardiotoxin treatment. Since increased cytoplasmic calcium concentrations characterize additional muscle pathological conditions, including dystrophies, metformin treatment could prove a valuable strategy to ameliorate the conditions of patients affected by dystrophies.
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Affiliation(s)
| | - Stefano Cannata
- Department of Biology, University of Rome Tor Vergata, Rome, Italy
| | - Claudia Fuoco
- Department of Biology, University of Rome Tor Vergata, Rome, Italy
| | | | - Stefano Testa
- Department of Biology, University of Rome Tor Vergata, Rome, Italy
| | | | | | - Luisa Castagnoli
- Department of Biology, University of Rome Tor Vergata, Rome, Italy
| | - Cesare Gargioli
- Department of Biology, University of Rome Tor Vergata, Rome, Italy
- * E-mail: (CG); (GC)
| | - Gianni Cesareni
- Department of Biology, University of Rome Tor Vergata, Rome, Italy
- Fondazione Santa Lucia Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Rome, Italy
- * E-mail: (CG); (GC)
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Ismail HM, Dorchies OM, Perozzo R, Strosova MK, Scapozza L, Ruegg UT. Inhibition of iPLA2 β and of stretch-activated channels by doxorubicin alters dystrophic muscle function. Br J Pharmacol 2014; 169:1537-50. [PMID: 23849042 DOI: 10.1111/bph.12188] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2012] [Revised: 02/28/2013] [Accepted: 03/15/2013] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND AND PURPOSE Chronic elevation in intracellular Ca(2+) concentration participates in death of skeletal muscle from mdx mice, a model for Duchenne muscular dystrophy (DMD). Candidate pathways mediating this Ca(2+) overload involve store-operated channels (SOCs) and stretch-activated channels (SACs), which are modulated by the Ca(2+) -independent form of PL A2 (iPLA2 ). We investigated the effect of doxorubicin (Dox), a chemotherapeutic agent reported to inhibit iPLA2 in other systems, on the activity of this enzyme and on the consequences on Ca(2+) handling and muscle function in mdx mice. EXPERIMENTAL APPROACH Effects of Dox on iPLA2 activity, reactive oxygen species production and on Ca(2+) influx were investigated in C2C12 and mdx myotubes. The mechanism of Dox-mediated iPLA2 inhibition was evaluated using purified 6x histidine-tagged enzyme. Aequorin technology was used to assess Ca(2+) concentrations underneath the plasma membrane. Isolated muscles were exposed to fatigue protocols and eccentric contractions to evaluate the effects of Dox on muscle function. KEY RESULTS Dox at 1-30 μM inhibited iPLA2 activity in cells and in the purified enzyme. Dox also inhibited SAC- but not SOC-mediated Ca(2+) influx in myotubes. Stimulated elevations of Ca(2+) concentrations below the plasmalemma were also blocked. Exposure of excised muscle to Dox was not deleterious to force production and promoted recovery from eccentric contractions. CONCLUSIONS AND IMPLICATIONS Dox showed efficacy against targets known to play a role in the pathology of DMD, namely iPLA2 and SAC. The potent SAC inhibitory effect of Dox is a novel finding that can explain partly the cardiomyopathy seen in chronic anthracycline treatment.
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Affiliation(s)
- H M Ismail
- Pharmacology, Geneva-Lausanne School of Pharmaceutical Sciences, University of Geneva and University of Lausanne, Geneva, Switzerland
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Diapocynin, a dimer of the NADPH oxidase inhibitor apocynin, reduces ROS production and prevents force loss in eccentrically contracting dystrophic muscle. PLoS One 2014; 9:e110708. [PMID: 25329652 PMCID: PMC4201587 DOI: 10.1371/journal.pone.0110708] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2013] [Accepted: 09/24/2014] [Indexed: 11/19/2022] Open
Abstract
Elevation of intracellular Ca2+, excessive ROS production and increased phospholipase A2 activity contribute to the pathology in dystrophin-deficient muscle. Moreover, Ca2+, ROS and phospholipase A2, in particular iPLA2, are thought to potentiate each other in positive feedback loops. NADPH oxidases (NOX) have been considered as a major source of ROS in muscle and have been reported to be overexpressed in muscles of mdx mice. We report here on our investigations regarding the effect of diapocynin, a dimer of the commonly used NOX inhibitor apocynin, on the activity of iPLA2, Ca2+ handling and ROS generation in dystrophic myotubes. We also examined the effects of diapocynin on force production and recovery ability of isolated EDL muscles exposed to eccentric contractions in vitro, a damaging procedure to which dystrophic muscle is extremely sensitive. In dystrophic myotubes, diapocynin inhibited ROS production, abolished iPLA2 activity and reduced Ca2+ influx through stretch-activated and store-operated channels, two major pathways responsible for excessive Ca2+ entry in dystrophic muscle. Diapocynin also prevented force loss induced by eccentric contractions of mdx muscle close to the value of wild-type muscle and reduced membrane damage as seen by Procion orange dye uptake. These findings support the central role played by NOX-ROS in the pathogenic cascade leading to muscular dystrophy and suggest diapocynin as an effective NOX inhibitor that might be helpful for future therapeutic approaches.
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Abstract
Muscular dystrophies are a group of diseases characterised by the primary wasting of skeletal muscle, which compromises patient mobility and in the most severe cases originate a complete paralysis and premature death. Existing evidence implicates calcium dysregulation as an underlying crucial event in the pathophysiology of several muscular dystrophies, such as dystrophinopathies, calpainopathies or myotonic dystrophy among others. Duchenne muscular dystrophy is the most frequent myopathy in childhood, and calpainopathy or LGMD2A is the most common form of limb-girdle muscular dystrophy, whereas myotonic dystrophy is the most frequent inherited muscle disease worldwide. In this review, we summarise recent advances in our understanding of calcium ion cycling through the sarcolemma, the sarcoplasmic reticulum and mitochondria, and its involvement in the pathogenesis of these dystrophies. We also discuss some of the clinical implications of recent findings regarding Ca2+ handling as well as novel approaches to treat muscular dystrophies targeting Ca2+ regulatory proteins.
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Avdonin PV. Orai and TRP channels in skeletal muscle cells. BIOCHEMISTRY MOSCOW SUPPLEMENT SERIES A-MEMBRANE AND CELL BIOLOGY 2012. [DOI: 10.1134/s1990747812010023] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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10
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Webb SE, Cheung CCY, Chan CM, Love DR, Miller AL. Application of complementary luminescent and fluorescent imaging techniques to visualize nuclear and cytoplasmic Ca²⁺ signalling during the in vivo differentiation of slow muscle cells in zebrafish embryos under normal and dystrophic conditions. Clin Exp Pharmacol Physiol 2012; 39:78-86. [PMID: 21824171 DOI: 10.1111/j.1440-1681.2011.05582.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
1. Evidence is accumulating for a role for Ca²⁺ signalling in the differentiation and development of embryonic skeletal muscle. 2. Imaging of intact, normally developing transgenic zebrafish that express the protein component of the Ca²⁺-sensitive complex aequorin, specifically in skeletal muscle, show that two distinct periods of spontaneous synchronised Ca²⁺ transients occur in the trunk: one at approximately 17.5-19.5 h post-fertilization (h.p.f.; termed signalling period SP1) and the other after approximately 23 h.p.f. (termed SP2). These periods of intense Ca²⁺ signalling activity are separated by a quiet period. 3. Higher-resolution confocal imaging of embryos loaded with the fluorescent Ca²⁺ reporter calcium green-1 dextran shows that the Ca²⁺ signals are generated almost exclusively in the slow muscle cells, the first muscle cells to differentiate, with distinct nuclear and cytoplasmic components. 4. Here, we show that coincidental with the SP1 Ca²⁺ signals, dystrophin becomes localized to the vertical myoseptae of the myotome. Introduction of a dmd morpholino (dmd-MO) resulted in no dystrophin being expressed in the vertical myoseptae, as well as a disruption of myotome morphology and sarcomere organization. In addition, the Ca²⁺ signalling signatures of dmd-MO-injected embryos or homozygous sapje mutant embryos were abnormal such that the frequency, amplitude and timing of the Ca²⁺ signals were altered compared with controls. 5. Our new data suggest that, in addition to a structural role, dystrophin may function in the regulation of [Ca²⁺](i) during the early stages of slow muscle cell differentiation when the Ca²⁺ signals generated in these cells coincide with the first spontaneous contractions of the trunk.
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Affiliation(s)
- Sarah E Webb
- Division of Life Science and Key State Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong SAR, China
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11
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Transient receptor potential channel activation and endothelium-dependent dilation in the systemic circulation. J Cardiovasc Pharmacol 2012; 57:133-9. [PMID: 20881603 DOI: 10.1097/fjc.0b013e3181fd35d1] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The endothelium plays a crucial role in the regulation of vascular tone by releasing a number of vasodilator mediators, including nitric oxide, prostacyclin, and endothelium-derived hyperpolarizing factor(s). The production of these mediators is typically initiated by an increase in intracellular Ca(2+) concentration ([Ca(2+)]i) in endothelial cells. An essential component of this Ca(2+) signal is the entry of Ca(2+) from the extracellular space through plasma membrane Ca(2+)-permeable channels. Although the molecular identification of the potential Ca(2+) entry channel(s) responsible for the release of endothelial relaxing factors is still evolving, accumulating evidence indicates that the transient receptor potential (TRP) channels, a superfamily of Ca(2+)-permeable cation channels, serve as an important mechanism of Ca(2+) entry in endothelial cells and other nonexcitable cells. The activation of these channels has been implicated in diverse endothelial functions ranging from control of vascular tone and regulation of vascular permeability to angiogenesis and vascular remodeling. This review summarizes recent evidence concerning TRP channels and endothelium-dependent dilation in several systemic vascular beds. In particular, we highlight the emerging roles of several TRP channels from the canonical and vanilloid subfamilies, including TRPV4, TRPC4, and TRPC6, in vasodilatory responses to shear stress and receptor agonists and discuss potential signaling mechanisms linking the TRP channel activation and the initiation of endothelium-derived hyperpolarizing factor-mediated responses in endothelial cells.
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Cárdenas C, Juretić N, Bevilacqua JA, García IE, Figueroa R, Hartley R, Taratuto AL, Gejman R, Riveros N, Molgó J, Jaimovich E. Abnormal distribution of inositol 1,4,5‐trisphosphate receptors in human muscle can be related to altered calcium signals and gene expression in Duchenne dystrophy‐derived cells. FASEB J 2010; 24:3210-21. [DOI: 10.1096/fj.09-152017] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- César Cárdenas
- Centro de Estudios Moleculares de la CélulaInstituto de Ciencias BiomédicasFacultad de MedicinaUniversidad de Chile Santiago Chile
- Department of PhysiologyUniversity of Pennsylvania Philadelphia Pennsylvania USA
- Centre National de la Recherche ScientifiqueInstitut de Neurobiologie Alfred FessardFRC2118Laboratoire de Neurobiologie Cellulaire et Moléculaire UPR9040 Gif sur Yvette France
| | - Nevenka Juretić
- Centro de Estudios Moleculares de la CélulaInstituto de Ciencias BiomédicasFacultad de MedicinaUniversidad de Chile Santiago Chile
- Centre National de la Recherche ScientifiqueInstitut de Neurobiologie Alfred FessardFRC2118Laboratoire de Neurobiologie Cellulaire et Moléculaire UPR9040 Gif sur Yvette France
| | - Jorge A. Bevilacqua
- Centro de Estudios Moleculares de la CélulaInstituto de Ciencias BiomédicasFacultad de MedicinaUniversidad de Chile Santiago Chile
- Programa de Anatomía y Biología del DesarrolloInstituto de Ciencias BiomédicasFacultad de MedicinaUniversidad de Chile Santiago Chile
- Departamento de Neurología y NeurocirugíaHospital Clínico Universidad de Chile Independencia Chile
- Centre National de la Recherche ScientifiqueInstitut de Neurobiologie Alfred FessardFRC2118Laboratoire de Neurobiologie Cellulaire et Moléculaire UPR9040 Gif sur Yvette France
| | - Isaac E. García
- Centro de Estudios Moleculares de la CélulaInstituto de Ciencias BiomédicasFacultad de MedicinaUniversidad de Chile Santiago Chile
- Centre National de la Recherche ScientifiqueInstitut de Neurobiologie Alfred FessardFRC2118Laboratoire de Neurobiologie Cellulaire et Moléculaire UPR9040 Gif sur Yvette France
| | - Reinaldo Figueroa
- Centro de Estudios Moleculares de la CélulaInstituto de Ciencias BiomédicasFacultad de MedicinaUniversidad de Chile Santiago Chile
- Centre National de la Recherche ScientifiqueInstitut de Neurobiologie Alfred FessardFRC2118Laboratoire de Neurobiologie Cellulaire et Moléculaire UPR9040 Gif sur Yvette France
| | - Ricardo Hartley
- Centro de Estudios Moleculares de la CélulaInstituto de Ciencias BiomédicasFacultad de MedicinaUniversidad de Chile Santiago Chile
- Centre National de la Recherche ScientifiqueInstitut de Neurobiologie Alfred FessardFRC2118Laboratoire de Neurobiologie Cellulaire et Moléculaire UPR9040 Gif sur Yvette France
| | - Ana L. Taratuto
- Departamento de NeuropatologíaInstituto de Investigaciones NeurológicasFLENI Buenos Aires Argentina
- Centre National de la Recherche ScientifiqueInstitut de Neurobiologie Alfred FessardFRC2118Laboratoire de Neurobiologie Cellulaire et Moléculaire UPR9040 Gif sur Yvette France
| | - Roger Gejman
- Departamento de Anatomía PatológicaFacultad de MedicinaPontificia Universidad Católica de Chile Santiago Chile
- Centre National de la Recherche ScientifiqueInstitut de Neurobiologie Alfred FessardFRC2118Laboratoire de Neurobiologie Cellulaire et Moléculaire UPR9040 Gif sur Yvette France
| | - Nora Riveros
- Centro de Estudios Moleculares de la CélulaInstituto de Ciencias BiomédicasFacultad de MedicinaUniversidad de Chile Santiago Chile
- Centre National de la Recherche ScientifiqueInstitut de Neurobiologie Alfred FessardFRC2118Laboratoire de Neurobiologie Cellulaire et Moléculaire UPR9040 Gif sur Yvette France
| | - Jordi Molgó
- Department of PhysiologyUniversity of Pennsylvania Philadelphia Pennsylvania USA
- Centre National de la Recherche ScientifiqueInstitut de Neurobiologie Alfred FessardFRC2118Laboratoire de Neurobiologie Cellulaire et Moléculaire UPR9040 Gif sur Yvette France
| | - Enrique Jaimovich
- Centro de Estudios Moleculares de la CélulaInstituto de Ciencias BiomédicasFacultad de MedicinaUniversidad de Chile Santiago Chile
- Centre National de la Recherche ScientifiqueInstitut de Neurobiologie Alfred FessardFRC2118Laboratoire de Neurobiologie Cellulaire et Moléculaire UPR9040 Gif sur Yvette France
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Itagaki K, Menconi M, Antoniu B, Zhang Q, Gonnella P, Soybel D, Hauser C, Hasselgren PO. Dexamethasone stimulates store-operated calcium entry and protein degradation in cultured L6 myotubes through a phospholipase A(2)-dependent mechanism. Am J Physiol Cell Physiol 2010; 298:C1127-39. [PMID: 20107037 DOI: 10.1152/ajpcell.00309.2009] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Muscle wasting in various catabolic conditions is at least in part regulated by glucocorticoids. Increased calcium levels have been reported in atrophying muscle. Mechanisms regulating calcium homeostasis in muscle wasting, in particular the role of glucocorticoids, are poorly understood. Here we tested the hypothesis that glucocorticoids increase intracellular calcium concentrations in skeletal muscle and stimulate store-operated calcium entry (SOCE) and that these effects of glucocorticoids may at least in part be responsible for glucocorticoid-induced protein degradation. Treatment of cultured myotubes with dexamethasone, a frequently used in vitro model of muscle wasting, resulted in increased intracellular calcium concentrations determined by fura-2 AM fluorescence measurements. When SOCE was measured by using calcium "add-back" to muscle cells after depletion of intracellular calcium stores, results showed that SOCE was increased 15-25% by dexamethasone and that this response to dexamethasone was inhibited by the store-operated calcium channel blocker BTP2. Dexamethasone treatment stimulated the activity of calcium-independent phospholipase A(2) (iPLA(2)), and dexamethasone-induced increase in SOCE was reduced by the iPLA(2) inhibitor bromoenol lactone (BEL). In additional experiments, treatment of myotubes with the store-operated calcium channel inhibitor gadolinium ion or BEL reduced dexamethasone-induced increase in protein degradation. Taken together, the results suggest that glucocorticoids increase calcium concentrations in myocytes and stimulate iPLA(2)-dependent SOCE and that glucocorticoid-induced muscle protein degradation may at least in part be regulated by increased iPLA(2) activity, SOCE, and cellular calcium levels.
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Affiliation(s)
- Kiyoshi Itagaki
- Dept. of Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
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14
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Webb SE, Rogers KL, Karplus E, Miller AL. The use of aequorins to record and visualize Ca(2+) dynamics: from subcellular microdomains to whole organisms. Methods Cell Biol 2010; 99:263-300. [PMID: 21035690 DOI: 10.1016/b978-0-12-374841-6.00010-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
In this chapter, we describe the practical aspects of measuring [Ca(2+)] transients that are generated in a particular cytoplasmic domain, or within a specific organelle or its periorganellar environment, using bioluminescent, genetically encoded and targeted Ca(2+) reporters, especially those based on apoaequorin. We also list examples of the organisms, tissues, and cells that have been transfected with apoaequorin or an apoaequorin-BRET complex, as well as of the organelles and subcellular domains that have been specifically targeted with these bioluminescent Ca(2+) reporters. In addition, we summarize the various techniques used to load the apoaequorin cofactor, coelenterazine, and its analogs into cells, tissues, and intact organisms, and we describe recent advances in the detection and imaging technologies that are currently being used to measure and visualize the luminescence generated by the aequorin-Ca(2+) reaction within these various cytoplasmic domains and subcellular compartments.
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Affiliation(s)
- Sarah E Webb
- Biochemistry and Cell Biology Section and State Key Laboratory of Molecular Neuroscience, Division of Life Science, HKUST, Clear Water Bay, Kowloon, Hong Kong, PR China
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15
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Mendoza SA, Fang J, Gutterman DD, Wilcox DA, Bubolz AH, Li R, Suzuki M, Zhang DX. TRPV4-mediated endothelial Ca2+ influx and vasodilation in response to shear stress. Am J Physiol Heart Circ Physiol 2009; 298:H466-76. [PMID: 19966050 DOI: 10.1152/ajpheart.00854.2009] [Citation(s) in RCA: 244] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The transient receptor potential vallinoid type 4 (TRPV4) channel has been implicated in the endothelial shear response and flow-mediated dilation, although the precise functions of this channel remain poorly understood. In the present study, we investigated the role of TRPV4 in shear stress-induced endothelial Ca(2+) entry and the potential link between this signaling response and relaxation of small resistance arteries. Using immunohistochemical analysis and RT-PCR, we detected strong expression of TRPV4 protein and mRNA in the endothelium in situ and endothelial cells freshly isolated from mouse small mesenteric arteries. The selective TRPV4 agonist GSK1016790A increased endothelial Ca(2+) and induced potent relaxation of small mesenteric arteries from wild-type (WT) but not TRPV4(-/-) mice. Luminal flow elicited endothelium-dependent relaxations that involved both nitric oxide and EDHFs. Both nitric oxide and EDHF components of flow-mediated relaxation were markedly reduced in TRPV4(-/-) mice compared with WT controls. Using a fura-2/Mn(2+) quenching assay, shear was observed to produce rapid Ca(2+) influx in endothelial cells, which was markedly inhibited by the TRPV4 channel blocker ruthenium red and TRPV4-specific short interfering RNA. Flow elicited a similar TRPV4-mediated Ca(2+) entry in HEK-293 cells transfected with TRPV4 channels but not in nontransfected cells. Collectively, these data indicate that TRPV4 may be a potential candidate of mechanosensitive channels in endothelial cells through which the shear stimulus is transduced into Ca(2+) signaling, leading to the release of endothelial relaxing factors and flow-mediated dilation of small resistance arteries.
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Affiliation(s)
- Suelhem A Mendoza
- Department of Medicine, Medical College of Wisconsin, 8701 Watertown Plank Rd., Milwaukee, WI 53226, USA
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16
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Eglen RM, Reisine T. Photoproteins: important new tools in drug discovery. Assay Drug Dev Technol 2009; 6:659-71. [PMID: 19035847 DOI: 10.1089/adt.2008.160] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The G protein-coupled receptor (GPCR) family is a major target for drug discovery, and most, if not all, GPCRs can couple to Ca2+ signaling. Consequently, there are a number of cellbased, primary, high-throughput screening (HTS) assays used for drug discovery that assess changes in intracellular Ca2+ as a functional readout of GPCR activation. Historically, changes in intracellular Ca2+ levels have been readily detected using fluorescent dyes that emit light in proportion to changes in intracellular Ca2+ concentration. An alternative approach to indirectly measure changes in Ca2+ concentrations involves the use of recombinantly expressed biosensor photoproteins, of which aequorin is a prototypic example. These biosensors have the advantage that they provide an intense luminescent signal in response to elevations in intracellular Ca2+. This exquisite sensitivity, the high signal-to-noise ratios, and the ability to target expression to discrete subcellular sites (in order to detect Ca2+ microdomains) have made photoproteins a principal choice in a wide range of GPCR drug discovery programs. Photoproteins are also finding increasing use in detecting activation of other molecular target classes such as ligand-gated ion channels and transporters. This review focuses upon the use of calcium photoproteins principally for use in GPCR drug discovery and HTS.
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Affiliation(s)
- Richard M Eglen
- Bio-discovery, PerkinElmer Life and Analytical Sciences, Waltham, MA 02451, USA.
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17
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Avdonin PV, Surkov KV, Sukhanova IF, Ruegg UT. Expression and functional role of the protein Orai-1 in skeletal myoblasts and myotubes. BIOCHEMISTRY (MOSCOW) SUPPLEMENT SERIES A: MEMBRANE AND CELL BIOLOGY 2008. [DOI: 10.1134/s1990747808040107] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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18
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Krüger J, Kunert-Keil C, Bisping F, Brinkmeier H. Transient receptor potential cation channels in normal and dystrophic mdx muscle. Neuromuscul Disord 2008; 18:501-13. [PMID: 18504127 DOI: 10.1016/j.nmd.2008.04.003] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2008] [Revised: 03/28/2008] [Accepted: 04/08/2008] [Indexed: 10/22/2022]
Abstract
To investigate the defective calcium regulation of dystrophin-deficient muscle fibres we studied gene expression and localization of non-voltage gated cation channels in normal and mdx mouse skeletal muscle. We found TRPC3, TRPC6, TRPV4, TRPM4 and TRPM7 to be the most abundant isoforms. Immunofluorescent staining of muscle cross-sections with antibodies against TRP proteins showed sarcolemmal localization of TRPC6 and TRPM7, both, for mdx and control. TRPV4 was found only in a fraction of fibres at the sarcolemma and around myonuclei, while TRPC3 staining revealed intracellular patches, preferentially in mdx muscle. Transcripts of low abundance coding for TRPC5, TRPA1 and TRPM1 channels were increased in mdx skeletal muscle at certain stages. The increased Ca(2+)-influx into dystrophin-deficient mdx fibres cannot be explained by increased gene expression of major TRP channels. However, a constant TRP channel expression in combination with the well described weaker Ca(2+)-handling system of mdx fibres may indicate an imbalance between Ca(2+)-influx and cellular Ca(2+)-control.
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Affiliation(s)
- Jana Krüger
- Institute of Pathophysiology, Ernst Moritz Arndt University of Greifswald, Greifswalder Street 11C, D-17495 Karlsburg, Germany
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19
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Hopf FW, Turner PR, Steinhardt RA. Calcium misregulation and the pathogenesis of muscular dystrophy. Subcell Biochem 2007; 45:429-464. [PMID: 18193647 DOI: 10.1007/978-1-4020-6191-2_16] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Although the exact nature of the relationship between calcium and the pathogenesis of Duchenne muscular dystrophy (DMD) is not fully understood, this is an important issue which has been addressed in several recent reviews (Alderton and Steinhardt, 2000a, Gailly, 2002, Allen et al., 2005). A key question when trying to understand the cellular basis of DMD is how the absence or low level of expression of dystrophin, a cytoskeletal protein, results in the slow but progressive necrosis of muscle fibres. Although loss of cytoskeletal and sarcolemmal integrity which results from the absence of dystrophin clearly plays a key role in the pathogenesis associated with DMD, a number of lines of evidence also establish a role for misregulation of calcium ions in the DMD pathology, particularly in the cytoplasmic space just under the sarcolemma. A number of calcium-permeable channels have been identified which can exhibit greater activity in dystrophic muscle cells, and exIsting evidence suggests that these may represent different variants of the same channel type (perhaps the transient receptor potential channel, TRPC). In addition, a prominent role for calcium-activated proteases in the DMD pathology has been established, as well as modulation of other intracellular regulatory proteins and signaling pathways. Whether dystrophin and its associated proteins have a direct role in the regulation of calcium ions, calcium channels or intracellular calcium stores, or indirectly alters calcium regulation through enhancement of membrane tearing, remains unclear. Here we focus on areas of consensus or divergence amongst the existing literature, and propose areas where future research would be especially valuable.
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Affiliation(s)
- F W Hopf
- Ernest Gallo Clinic and Research Center, University of California, San Francisco, 5858 Horton St., Suite 200, Emeryville, CA 94608, USA.
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20
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Nsaibia S, Wagner S, Rondé P, Warter JM, Poindron P, Aouni M, Dorchies OM. The difficult-to-cultivate coxsackieviruses A can productively multiply in primary culture of mouse skeletal muscle. Virus Res 2007; 123:30-9. [PMID: 16956688 DOI: 10.1016/j.virusres.2006.07.016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2005] [Revised: 07/15/2006] [Accepted: 07/27/2006] [Indexed: 11/26/2022]
Abstract
Coxsackieviruses A (CVA) are associated with several clinical manifestations such as aseptic meningitis and paralytic syndromes in humans. Most CVA are difficult-to-cultivate, which impedes their propagation and isolation from clinical material. Here, we tested the ability of cultivable (CVA-13, CVA-14), and difficult-to-cultivate (CVA-6, CVA-22) strains to infect primary cultures of skeletal muscle cells established from newborn mice. We found that such cultures sustained the multiplication of these CVA, as evidenced by the development of a cytopathic effect, already in the initial preparation or after passaging once. Cultures established for no more than 24h were sensitive to infection whereas older preparations were resistant. Using confocal microscopy after double-immunolabeling of the VP1 capsid protein and the muscle cell marker myosin, we demonstrated that only the myoblasts were infected, resulting in VP1 expression throughout their cytoplasm. Inoculation of infected cultures to suckling mice resulted in paralysis indicating that infection was productive. The nature of candidate receptors for virus entry in such cultures and the influence of cell culture conditions on the expression of these putative receptors are discussed. This work suggests that primary cultures of skeletal muscle cells could be used to propagate and isolate any CVA strain.
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Affiliation(s)
- Siwar Nsaibia
- Louis Pasteur University-Strasbourg II, School of Pharmacy, Laboratoire de Pathologie des Communications entre Cellules Nerveuses et Musculaires, EA 3427, 67401 Illkirch, France
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21
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Abstract
Skeletal muscle is the largest single organ of the body. Skeletal muscle damage may lead to loss of muscle function, and widespread muscle damage may have serious systemic implications due to leakage of intracellular constituents to the circulation. Ca2+ acts as a second messenger in all muscle and may activate a whole range of processes ranging from activation of contraction to degradation of the muscle cell. It is therefore of vital importance for the muscle cell to control [Ca2+] in the cytoplasm ([Ca2+]c). If the permeability of the sarcolemma for Ca2+ is increased, the muscle cell may suffer Ca2+ overload, defined as an inability to control [Ca2+]c. This could lead to the activation of calpains, resulting in proteolysis of cellular constituents, activation of phospholipase A2 (PLA2), affecting membrane integrity, an increased production of reactive oxygen species (ROS), causing lipid peroxidation, and possibly mitochondrial Ca2+ overload, all of which may further worsen the damage in a self-reinforcing process. An increased influx of Ca2+ leading to Ca2+ overload in muscle may occur in a range of situations such as exercise, mechanical and electrical trauma, prolonged ischemia, Duchenne muscular dystrophy, and cachexia. Counteractions include membrane stabilizing agents, Ca2+ channel blockers, calpain inhibitors, PLA2 inhibitors, and ROS scavengers.
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Affiliation(s)
- Hanne Gissel
- Institute of Physiology and Biophysics, University of Aarhus, Ole Worms Alle 1160, DK-8000 Arhus C, Denmark.
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22
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Boittin FX, Petermann O, Hirn C, Mittaud P, Dorchies OM, Roulet E, Ruegg UT. Ca2+-independent phospholipase A2 enhances store-operated Ca2+ entry in dystrophic skeletal muscle fibers. J Cell Sci 2006; 119:3733-42. [PMID: 16926189 DOI: 10.1242/jcs.03184] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Duchenne muscular dystrophy is caused by deficiency of dystrophin and leads to progressive weakness. It has been proposed that the muscle degeneration occurring in this disease is caused by increased Ca2+ influx due to enhanced activity of cationic channels that are activated either by stretch of the plasma membrane (stretch-activated channels) or by Ca2+-store depletion (store-operated channels). Using both cytosolic Ca2+ measurements with Fura-2 and the manganese quench method, we show here that store-operated Ca2+ entry is greatly enhanced in dystrophic skeletal flexor digitorum brevis fibers isolated from mdx5cv mice, a mouse model of Duchenne muscular dystrophy. Moreover, we show for the first time that store-operated Ca2+ entry in these fibers is under the control of the Ca2+-independent phospholipase A2 and that the exaggerated Ca2+ influx can be completely attenuated by inhibitors of this enzyme. Enhanced store-operated Ca2+ entry in dystrophic fibers is likely to be due to a near twofold overexpression of Ca2+-independent phospholipase A2. The Ca2+-independent phospholipase A2 pathway therefore appears as an attractive target to reduce excessive Ca2+ influx and subsequent degeneration occurring in dystrophic fibers.
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Affiliation(s)
- François-Xavier Boittin
- Laboratory of Pharmacology, Geneva-Lausanne School of Pharmaceutical Sciences, University of Geneva, University of Lausanne, 1211 Geneva 4, Switzerland
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23
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Zayas R, Groshong JS, Gomez CM. Inositol-1,4,5-triphosphate receptors mediate activity-induced synaptic Ca2+ signals in muscle fibers and Ca2+ overload in slow-channel syndrome. Cell Calcium 2006; 41:343-52. [PMID: 16973214 DOI: 10.1016/j.ceca.2006.07.007] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2006] [Revised: 06/03/2006] [Accepted: 07/15/2006] [Indexed: 11/21/2022]
Abstract
Strict control of calcium entry through excitatory synaptic receptors is important for shaping synaptic responses, gene expression, and cell survival. Disruption of this control may lead to pathological accumulation of Ca2+. The slow-channel congenital myasthenic syndrome (SCS), due to mutations in muscle acetylcholine receptor (AChR), perturbs the kinetics of synaptic currents, leading to post-synaptic Ca2+ accumulation. To understand the regulation of calcium signaling at the neuromuscular junction (NMJ) and the etiology of Ca2+ overload in SCS we studied the role of sarcoplasmic Ca2+ stores in SCS. Using fura-2 loaded dissociated fibers activated with acetylcholine puffs, we confirmed that Ca2+ accumulates around wild type NMJ and discovered that Ca2+ accumulates significantly faster around the NMJ of SCS transgenic dissociated muscle fibers. Additionally, we determined that this process is dependant on the activation, altered kinetics, and movement of Ca2+ ions through the AChR, although, surprisingly, depletion of intracellular stores also prevents the accumulation of this cation around the NMJ. Finally, we concluded that the sarcoplasmic reticulum is the main source of Ca2+ and that inositol-1,4,5-triphosphate receptors (IP3R), and to a lesser degree L-type voltage gated Ca2+ channels, are responsible for the efflux of this cation from intracellular stores. These results suggest that a signaling system mediated by the activation of AChR, Ca2+, and IP3R is responsible for localized Ca2+ signals observed in muscle fibers and the Ca2+ overload observed in SCS.
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Affiliation(s)
- Roberto Zayas
- Department of Neuroscience and Neurology, University of Minnesota, Minneapolis, MN 55455, USA
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24
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Poburko D, Potter K, van Breemen E, Fameli N, Liao CH, Basset O, Ruegg UT, van Breemen C. Mitochondria buffer NCX-mediated Ca2+-entry and limit its diffusion into vascular smooth muscle cells. Cell Calcium 2006; 40:359-71. [PMID: 16806462 DOI: 10.1016/j.ceca.2006.04.031] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2005] [Revised: 03/11/2006] [Accepted: 04/12/2006] [Indexed: 11/17/2022]
Abstract
The reverse-mode of the Na(+)/Ca(2+)-exchanger (NCX) mediates Ca(2+)-entry in agonist-stimulated vascular smooth muscle (VSM) and plays a central role in salt-sensitive hypertension. We investigated buffering of Ca(2+)-entry by peripheral mitochondria upon NCX reversal in rat aortic smooth muscle cells (RASMC). [Ca(2+)] was measured in mitochondria ([Ca(2+)](MT)) and the sub-plasmalemmal space ([Ca(2+)](subPM)) with targeted aequorins and in the bulk cytosol ([Ca(2+)](i)) with fura-2. Substitution of extracellular Na(+) by N-methyl-d-glucamine transiently increased [Ca(2+)](MT) ( approximately 2microM) and [Ca(2+)](subPM) ( approximately 1.3microM), which then decreased to sustained plateaus. In contrast, Na(+)-substitution caused a delayed and tonic increase in [Ca(2+)](i) (<100nM). Inhibition of Ca(2+)-uptake by the sarcoplasmic reticulum (SR) (30microM cyclopiazonic acid) or mitochondria (2microM FCCP or 2microM ruthenium red) enhanced the elevation of [Ca(2+)](subPM). These treatments also abolished the delay in the [Ca(2+)](i) response to 0Na(+) and increased its amplitude. Extracellular ATP (1mM) caused a peak and plateau in [Ca(2+)](i), and only the plateau was inhibited by KB-R7943 (10microM), a selective blocker of reverse-mode NCX. Evidence for ATP-mediated NCX-reversal was also found in changes in [Na(+)](i). Mitochondria normally exhibited a transient elevation of [Ca(2+)] in response to ATP, but inhibiting the mitochondrial NCX with CGP-37157 (10microM) unmasked an agonist-induced increase in mitochondrial Ca(2+)-flux. This flux was blocked by KB-R7943. In summary, mitochondria and the sarcoplasmic reticulum co-operate to buffer changes in [Ca(2+)](i) due to agonist-induced NCX reversal.
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Affiliation(s)
- Damon Poburko
- Department of Anesthesiology, Pharmacology & Therapeutics, University of British Columbia, Vancouver, Canada V6T 1Z1; Child & Family Research Institute, Vancouver, Canada V5Z 4H4.
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25
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Basset O, Boittin FX, Cognard C, Constantin B, Ruegg U. Bcl-2 overexpression prevents calcium overload and subsequent apoptosis in dystrophic myotubes. Biochem J 2006; 395:267-76. [PMID: 16393138 PMCID: PMC1422769 DOI: 10.1042/bj20051265] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Duchenne muscular dystrophy (DMD) is a lethal disease caused by the lack of the cytoskeletal protein dystrophin. Altered calcium homoeostasis and increased calcium concentrations in dystrophic fibres may be responsible for the degeneration of muscle occurring in DMD. In the present study, we used subsarcolemmal- and mitochondrial-targeted aequorin to study the effect of the antiapoptotic Bcl-2 protein overexpression on carbachol-induced near-plasma membrane and mitochondrial calcium responses in myotubes derived from control C57 and dystrophic (mdx) mice. We show that Bcl-2 overexpression decreases subsarcolemmal and mitochondrial calcium overload that occurs during activation of nicotinic acetylcholine receptors in dystrophic myotubes. Moreover, our results suggest that overexpressed Bcl-2 protein may prevent near-plasma membrane and mitochondrial calcium overload by inhibiting IP3Rs (inositol 1,4,5-trisphosphate receptors), which we have shown previously to be involved in abnormal calcium homoeostasis in dystrophic myotubes. Most likely as a consequence, the inhibition of IP3R function by Bcl-2 also inhibits calcium-dependent apoptosis in these cells.
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MESH Headings
- Animals
- Apoptosis/drug effects
- Calcium/metabolism
- Calcium Channels
- Cell Membrane/drug effects
- Cell Membrane/metabolism
- Cells, Cultured
- Gene Expression
- Inositol 1,4,5-Trisphosphate/pharmacology
- Inositol 1,4,5-Trisphosphate Receptors
- Mice
- Mice, Inbred C57BL
- Mice, Inbred mdx
- Mitochondria/metabolism
- Muscle Fibers, Skeletal/drug effects
- Muscle Fibers, Skeletal/metabolism
- Muscle Fibers, Skeletal/pathology
- Muscular Dystrophy, Animal/metabolism
- Muscular Dystrophy, Animal/pathology
- Protein Transport
- Proto-Oncogene Proteins c-bcl-2/genetics
- Proto-Oncogene Proteins c-bcl-2/metabolism
- Receptors, Cytoplasmic and Nuclear/antagonists & inhibitors
- Staurosporine/pharmacology
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Affiliation(s)
- Olivier Basset
- *Laboratory of Pharmacology, Geneva-Lausanne School of Pharmaceutical Sciences, University of Geneva, Quai Ernest Ansermet 30, CH-1211 Geneva 4, Switzerland
| | - François-Xavier Boittin
- *Laboratory of Pharmacology, Geneva-Lausanne School of Pharmaceutical Sciences, University of Geneva, Quai Ernest Ansermet 30, CH-1211 Geneva 4, Switzerland
| | - Christian Cognard
- †Institut de Physiologie et Biologie Cellulaire, CNRS-UMR6187, University of Poitiers, 86022 Poitiers Cedex, France
| | - Bruno Constantin
- †Institut de Physiologie et Biologie Cellulaire, CNRS-UMR6187, University of Poitiers, 86022 Poitiers Cedex, France
| | - Urs T. Ruegg
- *Laboratory of Pharmacology, Geneva-Lausanne School of Pharmaceutical Sciences, University of Geneva, Quai Ernest Ansermet 30, CH-1211 Geneva 4, Switzerland
- To whom correspondence should be addressed (email )
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26
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Batchelor CL, Winder SJ. Sparks, signals and shock absorbers: how dystrophin loss causes muscular dystrophy. Trends Cell Biol 2006; 16:198-205. [PMID: 16515861 DOI: 10.1016/j.tcb.2006.02.001] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2005] [Revised: 01/17/2006] [Accepted: 02/16/2006] [Indexed: 11/20/2022]
Abstract
The dystrophin-glycoprotein complex (DGC) can be considered as a specialized adhesion complex, linking the extracellular matrix to the actin cytoskeleton, primarily in muscle cells. Mutations in several components of the DGC lead to its partial or total loss, resulting in various forms of muscular dystrophy. These typically manifest as progressive wasting diseases with loss of muscle integrity. Debate is ongoing about the precise function of the DGC: initially a strictly mechanical role was proposed but it has been suggested that there is aberrant calcium handling in muscular dystrophy and, more recently, changes in MAP kinase and GTPase signalling have been implicated in the aetiology of the disease. Here, we discuss new and interesting developments in these aspects of DGC function and attempt to rationalize the mechanical, calcium and signalling hypotheses to provide a unifying hypothesis of the underlying process of muscular dystrophy.
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Affiliation(s)
- Clare L Batchelor
- Centre for Developmental and Biomedical Genetics, Department of Biomedical Science, University of Sheffield, Western Bank, Sheffield, UK, S10 2TN
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27
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Church JE, Fulton D. Differences in eNOS Activity Because of Subcellular Localization Are Dictated by Phosphorylation State Rather than the Local Calcium Environment. J Biol Chem 2006; 281:1477-88. [PMID: 16257964 DOI: 10.1074/jbc.m505968200] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Nitric oxide (NO) produced in the endothelium via the enzyme endothelial nitric-oxide synthase (eNOS) is an important vasoactive compound. Wild-type (WT) eNOS is localized to the plasma membrane and perinuclear/Golgi region by virtue of N-terminal myristoylation and palmitoylation. Acylation-deficient mutants (G2AeNOS) remain cytosolic and release less NO in response to Ca2+-elevating agonists; a disparity that we hypothesized was attributed to the greater distance between G2AeNOS and plasma membrane Ca2+ influx channels. The reduced activity of G2AeNOS versus WT was reversed upon disruption of cellular integrity with detergents or sonication. NO production from both constructs relied almost exclusively on the influx of extracellular Ca2+, and elevating intracellular Ca2+ to saturating levels with 10 microM ionomycin in the presence of 10 mM extracellular Ca2+ equalized NO production. To identify the contribution of calcium to the differences in activity between these enzymes, we created Ca2+/CaM-independent eNOS mutants by deleting the two putative autoinhibitory domains of eNOS. There was no difference in NO production between WT and G2A-targeted Ca2+-independent eNOS, suggesting that Ca2+ was the factor responsible. When eNOS constructs were fused in-frame to the bioluminescent probe aequorin, membrane-bound probes were exposed to higher [Ca2+] in unstimulated cells but upon ionomycin stimulation, the probes experienced equal amounts of Ca2+. The WT and G2A enzymes displayed significant differences in the phosphorylation state of Ser617, Ser635, and Ser1179, and mutating all three sites to alanine or restoring phosphorylation with the phosphatase inhibitor calyculin abolished the differences in activity. We therefore conclude that the disparity in NO production between WTeNOS and G2AeNOS is not caused by different localized [Ca2+] upon stimulation with ionomycin, but rather differences in phosphorylation state between the two constructs.
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Affiliation(s)
- Jarrod E Church
- Vascular Biology Center and the Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta, Georgia 30912, USA
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