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Tian X, Zhang Y, Li X, Xiong Y, Wu T, Ai HW. A luciferase prosubstrate and a red bioluminescent calcium indicator for imaging neuronal activity in mice. Nat Commun 2022; 13:3967. [PMID: 35803917 PMCID: PMC9270435 DOI: 10.1038/s41467-022-31673-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Accepted: 06/28/2022] [Indexed: 01/25/2023] Open
Abstract
Although fluorescent indicators have been broadly utilized for monitoring bioactivities, fluorescence imaging, when applied to mammals, is limited to superficial targets or requires invasive surgical procedures. Thus, there is emerging interest in developing bioluminescent indicators for noninvasive mammalian imaging. Bioluminescence imaging (BLI) of neuronal activity is highly desired but hindered by insufficient photons needed to digitalize fast brain activities. In this work, we develop a luciferase prosubstrate deliverable at an increased dose and activated in vivo by nonspecific esterase. We further engineer a bright, bioluminescent indicator with robust responsiveness to calcium ions (Ca2+) and appreciable emission above 600 nm. Integration of these advantageous components enables the imaging of the activity of neuronal ensembles in awake mice minimally invasively with excellent signal-to-background and subsecond temporal resolution. This study thus establishes a paradigm for studying brain function in health and disease.
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Affiliation(s)
- Xiaodong Tian
- grid.27755.320000 0000 9136 933XDepartment of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA 22908 USA ,grid.27755.320000 0000 9136 933XCenter for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA 22908 USA
| | - Yiyu Zhang
- grid.27755.320000 0000 9136 933XDepartment of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA 22908 USA ,grid.27755.320000 0000 9136 933XCenter for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA 22908 USA
| | - Xinyu Li
- grid.27755.320000 0000 9136 933XDepartment of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA 22908 USA ,grid.27755.320000 0000 9136 933XCenter for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA 22908 USA ,grid.411643.50000 0004 1761 0411Present Address: State Key Laboratory of Reproductive Regulation and Breeding of Grassland Livestock, School of Life Sciences, Inner Mongolia University, Hohhot, China
| | - Ying Xiong
- grid.27755.320000 0000 9136 933XDepartment of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA 22908 USA ,grid.27755.320000 0000 9136 933XCenter for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA 22908 USA
| | - Tianchen Wu
- grid.27755.320000 0000 9136 933XDepartment of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA 22908 USA ,grid.27755.320000 0000 9136 933XCenter for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA 22908 USA
| | - Hui-Wang Ai
- grid.27755.320000 0000 9136 933XDepartment of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA 22908 USA ,grid.27755.320000 0000 9136 933XCenter for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA 22908 USA ,grid.27755.320000 0000 9136 933XThe UVA Comprehensive Cancer Center, University of Virginia, Charlottesville, VA 22908 USA
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Abstract
Intracellular calcium mobilization can be measured using several methods varying in indicator dyes and devices used. In this chapter, we describe the fluorescence-based method (FLIPR Calcium 4 Assay) developed by Molecular Devices for a FlexStation and routinely used in our laboratory for detecting intracellular calcium changes. The assay is designed to study calcium mobilization induced by majority of GPCRs and calcium channels and allows for simultaneous concentration-dependent analysis of several receptor agonists and antagonists, useful in receptor characterization and drug discovery projects.
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3
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RedquorinXS Mutants with Enhanced Calcium Sensitivity and Bioluminescence Output Efficiently Report Cellular and Neuronal Network Activities. Int J Mol Sci 2020; 21:ijms21217846. [PMID: 33105848 PMCID: PMC7660078 DOI: 10.3390/ijms21217846] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Revised: 10/16/2020] [Accepted: 10/19/2020] [Indexed: 01/14/2023] Open
Abstract
Considerable efforts have been focused on shifting the wavelength of aequorin Ca2+-dependent blue bioluminescence through fusion with fluorescent proteins. This approach has notably yielded the widely used GFP-aequorin (GA) Ca2+ sensor emitting green light, and tdTomato-aequorin (Redquorin), whose bioluminescence is completely shifted to red, but whose Ca2+ sensitivity is low. In the present study, the screening of aequorin mutants generated at twenty-four amino acid positions in and around EF-hand Ca2+-binding domains resulted in the isolation of six aequorin single or double mutants (AequorinXS) in EF2, EF3, and C-terminal tail, which exhibited markedly higher Ca2+ sensitivity than wild-type aequorin in vitro. The corresponding Redquorin mutants all showed higher Ca2+ sensitivity than wild-type Redquorin, and four of them (RedquorinXS) matched the Ca2+ sensitivity of GA in vitro. RedquorinXS mutants exhibited unaltered thermostability and peak emission wavelengths. Upon stable expression in mammalian cell line, all RedquorinXS mutants reported the activation of the P2Y2 receptor by ATP with higher sensitivity and assay robustness than wt-Redquorin, and one, RedquorinXS-Q159T, outperformed GA. Finally, wide-field bioluminescence imaging in mouse neocortical slices showed that RedquorinXS-Q159T and GA similarly reported neuronal network activities elicited by the removal of extracellular Mg2+. Our results indicate that RedquorinXS-Q159T is a red light-emitting Ca2+ sensor suitable for the monitoring of intracellular signaling in a variety of applications in cells and tissues, and is a promising candidate for the transcranial monitoring of brain activities in living mice.
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Gökerküçük EB, Tramier M, Bertolin G. Imaging Mitochondrial Functions: from Fluorescent Dyes to Genetically-Encoded Sensors. Genes (Basel) 2020; 11:E125. [PMID: 31979408 PMCID: PMC7073610 DOI: 10.3390/genes11020125] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2019] [Revised: 01/20/2020] [Accepted: 01/21/2020] [Indexed: 12/18/2022] Open
Abstract
Mitochondria are multifunctional organelles that are crucial to cell homeostasis. They constitute the major site of energy production for the cell, they are key players in signalling pathways using secondary messengers such as calcium, and they are involved in cell death and redox balance paradigms. Mitochondria quickly adapt their dynamics and biogenesis rates to meet the varying energy demands of the cells, both in normal and in pathological conditions. Therefore, understanding simultaneous changes in mitochondrial functions is crucial in developing mitochondria-based therapy options for complex pathological conditions such as cancer, neurological disorders, and metabolic syndromes. To this end, fluorescence microscopy coupled to live imaging represents a promising strategy to track these changes in real time. In this review, we will first describe the commonly available tools to follow three key mitochondrial functions using fluorescence microscopy: Calcium signalling, mitochondrial dynamics, and mitophagy. Then, we will focus on how the development of genetically-encoded fluorescent sensors became a milestone for the understanding of these mitochondrial functions. In particular, we will show how these tools allowed researchers to address several biochemical activities in living cells, and with high spatiotemporal resolution. With the ultimate goal of tracking multiple mitochondrial functions simultaneously, we will conclude by presenting future perspectives for the development of novel genetically-encoded fluorescent biosensors.
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Affiliation(s)
| | | | - Giulia Bertolin
- Univ Rennes, CNRS, IGDR [Institut de génétique et développement de Rennes] UMR 6290, F-35000 Rennes, France
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5
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Vicente M, Salgado-Almario J, Soriano J, Burgos M, Domingo B, Llopis J. Visualization of Mitochondrial Ca 2+ Signals in Skeletal Muscle of Zebrafish Embryos with Bioluminescent Indicators. Int J Mol Sci 2019; 20:ijms20215409. [PMID: 31671636 PMCID: PMC6862566 DOI: 10.3390/ijms20215409] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 10/25/2019] [Accepted: 10/28/2019] [Indexed: 01/16/2023] Open
Abstract
Mitochondria are believed to play an important role in shaping the intracellular Ca2+ transients during skeletal muscle contraction. There is discussion about whether mitochondrial matrix Ca2+ dynamics always mirror the cytoplasmic changes and whether this happens in vivo in whole organisms. In this study, we characterized cytosolic and mitochondrial Ca2+ signals during spontaneous skeletal muscle contractions in zebrafish embryos expressing bioluminescent GFP-aequorin (GA, cytoplasm) and mitoGFP-aequorin (mitoGA, trapped in the mitochondrial matrix). The Ca2+ transients measured with GA and mitoGA reflected contractions of the trunk observed by transmitted light. The mitochondrial uncoupler FCCP and the inhibitor of the mitochondrial calcium uniporter (MCU), DS16570511, abolished mitochondrial Ca2+ transients whereas they increased the frequency of cytosolic Ca2+ transients and muscle contractions, confirming the subcellular localization of mitoGA. Mitochondrial Ca2+ dynamics were also determined with mitoGA and were found to follow closely cytoplasmic changes, with a slower decay. Cytoplasmic Ca2+ kinetics and propagation along the trunk and tail were characterized with GA and with the genetically encoded fluorescent Ca2+ indicator, Twitch-4. Although fluorescence provided a better spatio-temporal resolution, GA was able to resolve the same kinetic parameters while allowing continuous measurements for hours.
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Affiliation(s)
- Manuel Vicente
- Physiology and Cell Dynamics Group, Centro Regional de Investigaciones Biomédicas (CRIB) and Facultad de Medicina de Albacete, Universidad de Castilla-La Mancha, C/Almansa 14, 02006 Albacete, Spain.
| | - Jussep Salgado-Almario
- Physiology and Cell Dynamics Group, Centro Regional de Investigaciones Biomédicas (CRIB) and Facultad de Medicina de Albacete, Universidad de Castilla-La Mancha, C/Almansa 14, 02006 Albacete, Spain.
| | - Joaquim Soriano
- Physiology and Cell Dynamics Group, Centro Regional de Investigaciones Biomédicas (CRIB) and Facultad de Medicina de Albacete, Universidad de Castilla-La Mancha, C/Almansa 14, 02006 Albacete, Spain.
| | - Miguel Burgos
- Physiology and Cell Dynamics Group, Centro Regional de Investigaciones Biomédicas (CRIB) and Facultad de Medicina de Albacete, Universidad de Castilla-La Mancha, C/Almansa 14, 02006 Albacete, Spain.
| | - Beatriz Domingo
- Physiology and Cell Dynamics Group, Centro Regional de Investigaciones Biomédicas (CRIB) and Facultad de Medicina de Albacete, Universidad de Castilla-La Mancha, C/Almansa 14, 02006 Albacete, Spain.
| | - Juan Llopis
- Physiology and Cell Dynamics Group, Centro Regional de Investigaciones Biomédicas (CRIB) and Facultad de Medicina de Albacete, Universidad de Castilla-La Mancha, C/Almansa 14, 02006 Albacete, Spain.
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Talmon M, Rossi S, Lim D, Pollastro F, Palattella G, Ruffinatti FA, Marotta P, Boldorini R, Genazzani AA, Fresu LG. Absinthin, an agonist of the bitter taste receptor hTAS2R46, uncovers an ER-to-mitochondria Ca 2+-shuttling event. J Biol Chem 2019; 294:12472-12482. [PMID: 31248983 DOI: 10.1074/jbc.ra119.007763] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2019] [Revised: 06/17/2019] [Indexed: 01/04/2023] Open
Abstract
Type 2 taste receptors (TAS2R) are G protein-coupled receptors first described in the gustatory system, but have also been shown to have extraoral localizations, including airway smooth muscle (ASM) cells, in which TAS2R have been reported to induce relaxation. TAS2R46 is an unexplored subtype that responds to its highly specific agonist absinthin. Here, we first demonstrate that, unlike other bitter-taste receptor agonists, absinthin alone (1 μm) in ASM cells does not induce Ca2+ signals but reduces histamine-induced cytosolic Ca2+ increases. To investigate this mechanism, we introduced into ASM cells aequorin-based Ca2+ probes targeted to the cytosol, subplasma membrane domain, or the mitochondrial matrix. We show that absinthin reduces cytosolic histamine-induced Ca2+ rises and simultaneously increases Ca2+ influx into mitochondria. We found that this effect is inhibited by the potent human TAS2R46 (hTAS2R46) antagonist 3β-hydroxydihydrocostunolide and is no longer evident in hTAS2R46-silenced ASM cells, indicating that it is hTAS2R46-dependent. Furthermore, these changes were sensitive to the mitochondrial uncoupler carbonyl cyanide p-(trifluoromethoxy)phenyl-hydrazone (FCCP); the mitochondrial calcium uniporter inhibitor KB-R7943 (carbamimidothioic acid); the cytoskeletal disrupter latrunculin; and an inhibitor of the exchange protein directly activated by cAMP (EPAC), ESI-09. Similarly, the β2 agonist salbutamol also could induce Ca2+ shuttling from cytoplasm to mitochondria, suggesting that this new mechanism might be generalizable. Moreover, forskolin and an EPAC activator mimicked this effect in HeLa cells. Our findings support the hypothesis that plasma membrane receptors can positively regulate mitochondrial Ca2+ uptake, adding a further facet to the ability of cells to encode complex Ca2+ signals.
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Affiliation(s)
- Maria Talmon
- Department of Health Sciences, School of Medicine, University of Piemonte Orientale, Via Solaroli, 17-28100 Novara, Italy
| | - Silvia Rossi
- Department of Health Sciences, School of Medicine, University of Piemonte Orientale, Via Solaroli, 17-28100 Novara, Italy
| | - Dmitry Lim
- Department of Pharmaceutical Sciences, University of Piemonte Orientale, Via Bovio, 6-28100 Novara, Italy
| | - Federica Pollastro
- Department of Pharmaceutical Sciences, University of Piemonte Orientale, Via Bovio, 6-28100 Novara, Italy
| | - Gioele Palattella
- Department of Health Sciences, School of Medicine, University of Piemonte Orientale, Via Solaroli, 17-28100 Novara, Italy
| | - Federico A Ruffinatti
- Department of Pharmaceutical Sciences, University of Piemonte Orientale, Via Bovio, 6-28100 Novara, Italy
| | - Patrizia Marotta
- Department of Pharmaceutical Sciences, University of Piemonte Orientale, Via Bovio, 6-28100 Novara, Italy
| | - Renzo Boldorini
- Department of Health Sciences, School of Medicine, University of Piemonte Orientale, Via Solaroli, 17-28100 Novara, Italy
| | - Armando A Genazzani
- Department of Pharmaceutical Sciences, University of Piemonte Orientale, Via Bovio, 6-28100 Novara, Italy.
| | - Luigia G Fresu
- Department of Health Sciences, School of Medicine, University of Piemonte Orientale, Via Solaroli, 17-28100 Novara, Italy.
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7
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Basso E, Rigotto G, Zucchetti AE, Pozzan T. Slow activation of fast mitochondrial Ca 2+ uptake by cytosolic Ca 2. J Biol Chem 2018; 293:17081-17094. [PMID: 30228190 DOI: 10.1074/jbc.ra118.002332] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Revised: 09/06/2018] [Indexed: 11/06/2022] Open
Abstract
Mitochondrial Ca2+ uptake through the mitochondrial Ca2+ uniporter (MCU) is a tightly controlled process that sustains cell functions mainly by fine-tuning oxidative metabolism to cellular needs. The kinetics of Ca2+ fluxes across the mitochondrial membranes have been studied both in vitro and in vivo for many years, and the discovery of the molecular components of the MCU has further clarified that this Ca2+ uptake mechanism is based on a complex system subject to elaborate layers of controls. Alterations in the speed or capacity of the in-and-out pathways can have detrimental consequences for both the organelle and the cell, impairing cellular metabolism and ultimately causing cell death. Here, we report that pretreatment of deenergized mitochondria with low-micromolar Ca2+ concentrations for a few minutes markedly increases the speed of mitochondrial Ca2+ uptake upon re-addition of an oxidizable substrate. We found that this phenomenon is sensitive to alterations in the level of the MCU modulator proteins mitochondrial calcium uptake 1 (MICU1) and 2 (MICU2), and is accompanied by changes in the association of MICU1-MICU2 complexes with MCU. This increased Ca2+ uptake capacity, occurring under conditions mimicking those during ischemia/reperfusion in vivo, could lead to a massive amount of Ca2+ entering the mitochondrial matrix even at relatively low levels of cytosolic Ca2+ We conclude that the phenomenon uncovered here represents a potential threat of mitochondrial Ca2+ overload to the cell.
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Affiliation(s)
- Emy Basso
- From the National Research Council, Department of Biomedical Science, Neuroscience Institute (Padua Section), 35131 Padua, Italy,
| | - Giulia Rigotto
- the Department of Biomedical Sciences, University of Padua, 35131 Padua, Italy
| | - Andrés E Zucchetti
- the Institut Curie, PSL Research University, INSERM, U932, 26 rue d'Ulm, 75248 Paris Cedex 05, France, and
| | - Tullio Pozzan
- From the National Research Council, Department of Biomedical Science, Neuroscience Institute (Padua Section), 35131 Padua, Italy.,the Department of Biomedical Sciences, University of Padua, 35131 Padua, Italy.,the Venetian Institute of Molecular Medicine, 35129 Padua, Italy
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8
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Costa A, Navazio L, Szabo I. The contribution of organelles to plant intracellular Calcium signalling. JOURNAL OF EXPERIMENTAL BOTANY 2018; 69:4996169. [PMID: 29767757 DOI: 10.1093/jxb/ery185] [Citation(s) in RCA: 69] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Indexed: 05/18/2023]
Abstract
Calcium (Ca2+) is among the most important intracellular messengers in living organisms. Understanding of the players and dynamics of Ca2+ signalling pathways in plants may help to unravel the molecular basis of their exceptional flexibility to respond and to adapt to different stimuli. In the present review we focus on new tools that have recently revolutionized our view of organellar Ca2+ signalling as well as on the current knowledge regarding the pathways mediating Ca2+ fluxes across intracellular membranes. The contribution of organelles and cellular subcompartments to the orchestrated response via Ca2+ signalling within a cell is also discussed, underlining the fact that one of the greatest challenges in the field is the elucidation of how influx and efflux Ca2+ transporters/channels are regulated in a concerted manner to translate specific information into a Ca2+ signature.
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Affiliation(s)
- Alex Costa
- Department of Biosciences, University of Milan, Via G. Celoria, Milan, Italy
- Institute of Biophysics, Consiglio Nazionale delle Ricerche, Via G. Celoria, Milan, Italy
| | - Lorella Navazio
- Department of Biology, University of Padova, Via U. Bassi, Padova, Italy
- Botanical Garden, University of Padova, Via Orto Botanico, Padova, Italy
| | - Ildiko Szabo
- Department of Biology, University of Padova, Via U. Bassi, Padova, Italy
- Botanical Garden, University of Padova, Via Orto Botanico, Padova, Italy
- Institute of Neurosciences, Consiglio Nazionale delle Ricerche, Via U. Bassi, Padova, Italy
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Rutter GA, Hodson DJ, Chabosseau P, Haythorne E, Pullen TJ, Leclerc I. Local and regional control of calcium dynamics in the pancreatic islet. Diabetes Obes Metab 2017; 19 Suppl 1:30-41. [PMID: 28466490 DOI: 10.1111/dom.12990] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/21/2017] [Revised: 04/19/2017] [Accepted: 04/24/2017] [Indexed: 12/31/2022]
Abstract
Ca2+ is the key intracellular regulator of insulin secretion, acting in the β-cell as the ultimate trigger for exocytosis. In response to high glucose, ATP-sensitive K+ channel closure and plasma membrane depolarization engage a sophisticated machinery to drive pulsatile cytosolic Ca2+ changes. Voltage-gated Ca2+ channels, Ca2+ -activated K+ channels and Na+ /Ca2+ exchange all play important roles. The use of targeted Ca2+ probes has revealed that during each cytosolic Ca2+ pulse, uptake of Ca2+ by mitochondria, endoplasmic reticulum (ER), secretory granules and lysosomes fine-tune cytosolic Ca2+ dynamics and control organellar function. For example, changes in the expression of the Ca2+ -binding protein Sorcin appear to provide a link between ER Ca2+ levels and ER stress, affecting β-cell function and survival. Across the islet, intercellular communication between highly interconnected "hubs," which act as pacemaker β-cells, and subservient "followers," ensures efficient insulin secretion. Loss of connectivity is seen after the deletion of genes associated with type 2 diabetes (T2D) and follows metabolic and inflammatory insults that characterize this disease. Hubs, which typically comprise ~1%-10% of total β-cells, are repurposed for their specialized role by expression of high glucokinase (Gck) but lower Pdx1 and Nkx6.1 levels. Single cell-omics are poised to provide a deeper understanding of the nature of these cells and of the networks through which they communicate. New insights into the control of both the intra- and intercellular Ca2+ dynamics may thus shed light on T2D pathology and provide novel opportunities for therapy.
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Affiliation(s)
- Guy A Rutter
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, and the Imperial Pancreatic Islet Biology and Diabetes Consortium, Hammersmith Hospital, Imperial College London, London, UK
| | - David J Hodson
- Institute of Metabolism and Systems Research (IMSR), University of Birmingham, Edgbaston, UK
- Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, COMPARE University of Birmingham and University of Nottingham Midlands, Birmingham, UK
| | - Pauline Chabosseau
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, and the Imperial Pancreatic Islet Biology and Diabetes Consortium, Hammersmith Hospital, Imperial College London, London, UK
| | - Elizabeth Haythorne
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, and the Imperial Pancreatic Islet Biology and Diabetes Consortium, Hammersmith Hospital, Imperial College London, London, UK
| | - Timothy J Pullen
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, and the Imperial Pancreatic Islet Biology and Diabetes Consortium, Hammersmith Hospital, Imperial College London, London, UK
| | - Isabelle Leclerc
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, and the Imperial Pancreatic Islet Biology and Diabetes Consortium, Hammersmith Hospital, Imperial College London, London, UK
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Bassett JJ, Monteith GR. Genetically Encoded Calcium Indicators as Probes to Assess the Role of Calcium Channels in Disease and for High-Throughput Drug Discovery. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2017; 79:141-171. [PMID: 28528667 DOI: 10.1016/bs.apha.2017.01.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The calcium ion (Ca2+) is an important signaling molecule implicated in many cellular processes, and the remodeling of Ca2+ homeostasis is a feature of a variety of pathologies. Typical methods to assess Ca2+ signaling in cells often employ small molecule fluorescent dyes, which are sometimes poorly suited to certain applications such as assessment of cellular processes, which occur over long periods (hours or days) or in vivo experiments. Genetically encoded calcium indicators are a set of tools available for the measurement of Ca2+ changes in the cytosol and subcellular compartments, which circumvent some of the inherent limitations of small molecule Ca2+ probes. Recent advances in genetically encoded calcium sensors have greatly increased their ability to provide reliable monitoring of Ca2+ changes in mammalian cells. New genetically encoded calcium indicators have diverse options in terms of targeting, Ca2+ affinity and fluorescence spectra, and this will further enhance their potential use in high-throughput drug discovery and other assays. This review will outline the methods available for Ca2+ measurement in cells, with a focus on genetically encoded calcium sensors. How these sensors will improve our understanding of the deregulation of Ca2+ handling in disease and their application to high-throughput identification of drug leads will also be discussed.
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Affiliation(s)
- John J Bassett
- School of Pharmacy, The University of Queensland, Brisbane, QLD, Australia
| | - Gregory R Monteith
- School of Pharmacy, The University of Queensland, Brisbane, QLD, Australia; Mater Research, The University of Queensland, Brisbane, QLD, Australia.
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11
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Bakayan A, Domingo B, Vaquero CF, Peyriéras N, Llopis J. Fluorescent Protein-photoprotein Fusions and Their Applications in Calcium Imaging. Photochem Photobiol 2017; 93:448-465. [PMID: 27925224 DOI: 10.1111/php.12682] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Accepted: 09/19/2016] [Indexed: 12/21/2022]
Abstract
Calcium-activated photoproteins, such as aequorin, have been used as luminescent Ca2+ indicators since 1967. After the cloning of aequorin in 1985, microinjection was substituted by its heterologous expression, which opened the way for a widespread use. Molecular fusion of green fluorescent protein (GFP) to aequorin recapitulated the nonradiative energy transfer process that occurs in the jellyfish Aequorea victoria, from which these two proteins were obtained, resulting in an increase of light emission and a shift to longer wavelength. The abundance and location of the chimera are seen by fluorescence, whereas its luminescence reports Ca2+ levels. GFP-aequorin is broadly used in an increasing number of studies, from organelles and cells to intact organisms. By fusing other fluorescent proteins to aequorin, the available luminescence color palette has been expanded for multiplexing assays and for in vivo measurements. In this report, we will attempt to review the various photoproteins available, their reported fusions with fluorescent proteins and their biological applications to image Ca2+ dynamics in organelles, cells, tissue explants and in live organisms.
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Affiliation(s)
- Adil Bakayan
- BioEmergences Unit (CNRS, USR3695), Université Paris-Saclay, Gif-sur-Yvette, France
| | - Beatriz Domingo
- Centro Regional de Investigaciones Biomédicas (CRIB) and Facultad de Medicina de Albacete, Universidad de Castilla-La Mancha, Albacete, Spain
| | - Cecilia F Vaquero
- Centro Regional de Investigaciones Biomédicas (CRIB) and Facultad de Medicina de Albacete, Universidad de Castilla-La Mancha, Albacete, Spain
| | - Nadine Peyriéras
- BioEmergences Unit (CNRS, USR3695), Université Paris-Saclay, Gif-sur-Yvette, France
| | - Juan Llopis
- Centro Regional de Investigaciones Biomédicas (CRIB) and Facultad de Medicina de Albacete, Universidad de Castilla-La Mancha, Albacete, Spain
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12
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Neuroprotective profile of pyridothiazepines with blocking activity of the mitochondrial Na(+)/Ca(2+) exchanger. Eur J Med Chem 2015; 109:114-23. [PMID: 26774037 DOI: 10.1016/j.ejmech.2015.12.043] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Revised: 12/03/2015] [Accepted: 12/23/2015] [Indexed: 11/20/2022]
Abstract
The mitochondrial Na(+)/Ca(2+) exchanger plays an important role in the control of cytosolic Ca(2+) cycling in excitable cells, essential for the regulation of a plethora of Ca(2+)-dependent physio-pathological events, such as apoptosis in the presence of a Ca(2+) overload. There are very few pharmacological tools available to study both physiological and pathological implications of the mitochondrial Na(+)/Ca(2+) exchanger, where the benzothiazepine CGP37157 is the best-known ligand, used since the 1980s. However, it is not an efficient blocker and lacks of selectivity, as also blocks several other cellular Ca(2+) transporters. Moreover, CGP37157 is a very lipophilic drug, showing very poor water solubility, what has hindered its therapeutic use. Attempting to improve its pharmacokinetic profile as well as its potency and selectivity, we herein describe the synthesis of new CGP37157 analogs, where the benzene-fused ring has been replaced by a pyridine. On top of a better water solubility and lower log P value, some of these new pyridothiazepine derivatives also presented a higher capacity to regulate the mitochondrial Ca(2+) clearance, while keeping the neuroprotective properties presented in the head compound CGP37157.
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13
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Abstract
Intracellular calcium mobilization can be measured using several methods varying in indicator dyes and devices used. In this chapter, we describe the fluorescence-based method (FLIPR Calcium 4 Assay) developed by Molecular Devices for a FlexStation and routinely used in our laboratory for detecting intracellular calcium changes. The assay is designed to study calcium mobilization induced by majority of GPCRs and calcium channels and allows for simultaneous concentration-dependent analysis of several receptor agonists and antagonists, useful in receptor characterization and drug discovery projects.
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Affiliation(s)
- Grzegorz Woszczek
- Division of Asthma, Allergy and Lung Biology, King's College London, 5th Floor, Tower Wing, Guy's Hospital, London, SE1 9RT, UK,
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Bakayan A, Domingo B, Miyawaki A, Llopis J. Imaging Ca(2+) activity in mammalian cells and zebrafish with a novel red-emitting aequorin variant. Pflugers Arch 2014; 467:2031-42. [PMID: 25355614 PMCID: PMC4537489 DOI: 10.1007/s00424-014-1639-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Revised: 10/15/2014] [Accepted: 10/21/2014] [Indexed: 02/04/2023]
Abstract
Ca2+ monitoring with aequorin is an established bioluminescence technique, whereby the photoprotein emits blue light when it binds to Ca2+. However, aequorin’s blue emission and low quantum yield limit its application for in vivo imaging because blue-green light is greatly attenuated in animal tissues. In earlier work, aequorin was molecularly fused with green, yellow, and red fluorescent proteins, producing an emission shift through bioluminescence resonance energy transfer (BRET). We have previously shown that the chimera tandem dimer Tomato-aequorin (tdTA) emits red light in mammalian cells and across the skin and other tissues of mice [1]. In this work, we varied the configuration of the linker in tdTA to maximize energy transfer. One variant, named Redquorin, improved BRET from aequorin to tdTomato to almost a maximum value, and the emission above 575 nm exceeded 73 % of total counts. By pairing Redquorin with appropriate synthetic coelenterazines, agonist-induced and spontaneous Ca2+ oscillations in single HEK-293 cells were imaged. In addition, we also imaged Ca2+ transients associated with twitching behavior in developing zebrafish embryos expressing Redquorin during the segmentation period. Furthermore, the emission profile of Redquorin resulted in significant luminescence crossing a blood sample, a highly absorbing tissue. This new tool will facilitate in vivo imaging of Ca2+ from deep tissues of animals.
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Affiliation(s)
- Adil Bakayan
- Centro Regional de Investigaciones Biomédicas (CRIB) and Facultad de Medicina de Albacete, Universidad Castilla-La Mancha, C/ Almansa 14, 02008, Albacete, Spain
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15
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Calcium imaging perspectives in plants. Int J Mol Sci 2014; 15:3842-59. [PMID: 24599077 PMCID: PMC3975371 DOI: 10.3390/ijms15033842] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2013] [Revised: 02/18/2014] [Accepted: 02/20/2014] [Indexed: 11/26/2022] Open
Abstract
The calcium ion (Ca2+) is a versatile intracellular messenger. It provides dynamic regulation of a vast array of gene transcriptions, protein kinases, transcription factors and other complex downstream signaling cascades. For the past six decades, intracellular Ca2+ concentration has been significantly studied and still many studies are under way. Our understanding of Ca2+ signaling and the corresponding physiological phenomenon is growing exponentially. Here we focus on the improvements made in the development of probes used for Ca2+ imaging and expanding the application of Ca2+ imaging in plant science research.
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16
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Stabilisation of Recombinant Aequorin by Polyols: Activity, Thermostability and Limited Proteolysis. Appl Biochem Biotechnol 2013; 170:273-80. [DOI: 10.1007/s12010-013-0096-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2011] [Accepted: 01/08/2013] [Indexed: 11/26/2022]
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18
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Plovanich M, Bogorad RL, Sancak Y, Kamer KJ, Strittmatter L, Li AA, Girgis HS, Kuchimanchi S, De Groot J, Speciner L, Taneja N, OShea J, Koteliansky V, Mootha VK. MICU2, a paralog of MICU1, resides within the mitochondrial uniporter complex to regulate calcium handling. PLoS One 2013; 8:e55785. [PMID: 23409044 PMCID: PMC3567112 DOI: 10.1371/journal.pone.0055785] [Citation(s) in RCA: 355] [Impact Index Per Article: 32.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2012] [Accepted: 12/31/2012] [Indexed: 11/19/2022] Open
Abstract
Mitochondrial calcium uptake is present in nearly all vertebrate tissues and is believed to be critical in shaping calcium signaling, regulating ATP synthesis and controlling cell death. Calcium uptake occurs through a channel called the uniporter that resides in the inner mitochondrial membrane. Recently, we used comparative genomics to identify MICU1 and MCU as the key regulatory and putative pore-forming subunits of this channel, respectively. Using bioinformatics, we now report that the human genome encodes two additional paralogs of MICU1, which we call MICU2 and MICU3, each of which likely arose by gene duplication and exhibits distinct patterns of organ expression. We demonstrate that MICU1 and MICU2 are expressed in HeLa and HEK293T cells, and provide multiple lines of biochemical evidence that MCU, MICU1 and MICU2 reside within a complex and cross-stabilize each other's protein expression in a cell-type dependent manner. Using in vivo RNAi technology to silence MICU1, MICU2 or both proteins in mouse liver, we observe an additive impairment in calcium handling without adversely impacting mitochondrial respiration or membrane potential. The results identify MICU2 as a new component of the uniporter complex that may contribute to the tissue-specific regulation of this channel.
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Affiliation(s)
- Molly Plovanich
- Departments of Molecular Biology and Medicine, Massachusetts General Hospital, and Department of Systems Biology, Harvard Medical School, Boston, Massachusetts, United States of America
- Broad Institute, Cambridge, Massachusetts, United States of America
| | - Roman L. Bogorad
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Yasemin Sancak
- Departments of Molecular Biology and Medicine, Massachusetts General Hospital, and Department of Systems Biology, Harvard Medical School, Boston, Massachusetts, United States of America
- Broad Institute, Cambridge, Massachusetts, United States of America
| | - Kimberli J. Kamer
- Departments of Molecular Biology and Medicine, Massachusetts General Hospital, and Department of Systems Biology, Harvard Medical School, Boston, Massachusetts, United States of America
- Broad Institute, Cambridge, Massachusetts, United States of America
| | - Laura Strittmatter
- Departments of Molecular Biology and Medicine, Massachusetts General Hospital, and Department of Systems Biology, Harvard Medical School, Boston, Massachusetts, United States of America
- Broad Institute, Cambridge, Massachusetts, United States of America
| | - Andrew A. Li
- Departments of Molecular Biology and Medicine, Massachusetts General Hospital, and Department of Systems Biology, Harvard Medical School, Boston, Massachusetts, United States of America
- Broad Institute, Cambridge, Massachusetts, United States of America
| | - Hany S. Girgis
- Departments of Molecular Biology and Medicine, Massachusetts General Hospital, and Department of Systems Biology, Harvard Medical School, Boston, Massachusetts, United States of America
- Broad Institute, Cambridge, Massachusetts, United States of America
| | - Satya Kuchimanchi
- Alnylam Pharmaceuticals, Inc., Cambridge, Massachusetts, United States of America
| | - Jack De Groot
- Alnylam Pharmaceuticals, Inc., Cambridge, Massachusetts, United States of America
| | - Lauren Speciner
- Alnylam Pharmaceuticals, Inc., Cambridge, Massachusetts, United States of America
| | - Nathan Taneja
- Alnylam Pharmaceuticals, Inc., Cambridge, Massachusetts, United States of America
| | - Jonathan OShea
- Alnylam Pharmaceuticals, Inc., Cambridge, Massachusetts, United States of America
| | - Victor Koteliansky
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Vamsi K. Mootha
- Departments of Molecular Biology and Medicine, Massachusetts General Hospital, and Department of Systems Biology, Harvard Medical School, Boston, Massachusetts, United States of America
- Broad Institute, Cambridge, Massachusetts, United States of America
- * E-mail:
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19
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Tonelli FMP, Santos AK, Gomes DA, da Silva SL, Gomes KN, Ladeira LO, Resende RR. Stem cells and calcium signaling. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 740:891-916. [PMID: 22453975 DOI: 10.1007/978-94-007-2888-2_40] [Citation(s) in RCA: 90] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The increasing interest in stem cell research is linked to the promise of developing treatments for many lifethreatening, debilitating diseases, and for cell replacement therapies. However, performing these therapeutic innovations with safety will only be possible when an accurate knowledge about the molecular signals that promote the desired cell fate is reached. Among these signals are transient changes in intracellular Ca(2+) concentration [Ca(2+)](i). Acting as an intracellular messenger, Ca(2+) has a key role in cell signaling pathways in various differentiation stages of stem cells. The aim of this chapter is to present a broad overview of various moments in which Ca(2+)-mediated signaling is essential for the maintenance of stem cells and for promoting their development and differentiation, also focusing on their therapeutic potential.
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Affiliation(s)
- Fernanda M P Tonelli
- Nanomaterials Laboratory, Department of Physics, Insitute of Exact Sciences, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil
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20
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Conway BR, Demarest KT. The Use of Biosensors to Study GPCR Function: Applications for High-Content Screening. ACTA ACUST UNITED AC 2011. [DOI: 10.3109/10606820214641] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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21
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Cartwright EJ, Mohamed T, Oceandy D, Neyses L. Calcium signaling dysfunction in heart disease. Biofactors 2011; 37:175-81. [PMID: 21674639 DOI: 10.1002/biof.149] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/09/2010] [Accepted: 12/30/2010] [Indexed: 11/09/2022]
Abstract
In the heart, Ca(2+) is crucial for the regulation of contraction and intracellular signaling, processes, which are vital to the functioning of the healthy heart. Ca(2+) -activated signaling pathways must function against a background of large, rapid, and tightly regulated changes in intracellular free Ca(2+) concentrations during each contraction and relaxation cycle. This review highlights a number of proteins that regulate signaling Ca(2+) in both normal and pathological conditions including cardiac hypertrophy and heart failure, and discusses how these pathways are not regulated by the marked elevation in free intracellular calcium ([Ca(2+) ](i)) during contraction but require smaller sustained increases in Ca(2+) concentration. In addition, we present published evidence that the pool of Ca(2+) that regulates signaling is compartmentalized into distinct cellular microdomains and is thus distinct from that regulating contraction.
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Affiliation(s)
- Elizabeth J Cartwright
- Cardiovascular Medicine Research Group, Manchester Academic Health Science Centre, University of Manchester, UK.
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22
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Zeinoddini M, Khajeh K, Behzadian F, Hosseinkhani S, Saeedinia AR, Barjesteh H. Design and characterization of an aequorin-based bacterial biosensor for detection of toluene and related compounds. Photochem Photobiol 2011; 86:1071-5. [PMID: 20663082 DOI: 10.1111/j.1751-1097.2010.00775.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
An aequorin-based Escherichia coli strain JM109 biosensor was constructed and characterized for its potential to detect toluene and related compounds in aqueous solutions. The biosensor was constructed based on a PGL2 plasmid carrying the lower pathway promoter (Pu) of the xyl operon of Pseudomonas putida mt-2, which was incorporated with transcriptional activator xylR and fused to aequorin cDNA named pGL2-aequorin. Binding of xylR protein to a subset of toluene-like compounds activates transcription at the Pu promoter, thus expression of aequorin is controlled by xylR and Pu. In this work we have compared the effect of Shine-Dalgarno (SD) and T2 rrnβ terminator sequence in the expression of aequorin. According to the sensitivity of aequorin and increase in the signal-to-noise ratio, this reporter enzyme has reasonable sensitivity compared with other reporter systems. The results indicate higher expression of aequorin in the presence of SD and T2 rrnβ. The activity of aequorin in recombinant whole-cell biosensor was linear from 1 to 500 μm of toluene. The bioluminescence response was specific for toluene-like molecules, so this biosensor cells would be able to detect toluene derivative contamination in environmental samples, accurately.
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Affiliation(s)
- Mehdi Zeinoddini
- Department of Biochemistry, Faculty of Biological Science, Tarbiat Modares University, Tehran, Iran
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23
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MICU1 encodes a mitochondrial EF hand protein required for Ca(2+) uptake. Nature 2010; 467:291-6. [PMID: 20693986 PMCID: PMC2977980 DOI: 10.1038/nature09358] [Citation(s) in RCA: 681] [Impact Index Per Article: 48.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2010] [Accepted: 07/19/2010] [Indexed: 02/07/2023]
Abstract
Mitochondrial calcium uptake plays a central role in cell physiology by stimulating ATP production, shaping cytosolic calcium transients, and regulating cell death. The biophysical properties of mitochondrial calcium uptake have been studied in detail, but the underlying proteins remain elusive. Here, we utilize an integrative strategy to predict human genes involved in mitochondrial calcium entry based on clues from comparative physiology, evolutionary genomics, and organelle proteomics. RNA interference against 13 top candidates highlighted one gene that we now call mitochondrial calcium uptake 1 (MICU1). Silencing MICU1 does not disrupt mitochondrial respiration or membrane potential but abolishes mitochondrial calcium entry in intact and permeabilized cells, and attenuates the metabolic coupling between cytosolic calcium transients and activation of matrix dehydrogenases. MICU1 is associated with the organelle’s inner membrane and has two canonical EF hands that are essential for its activity, suggesting a role in calcium sensing. MICU1 represents the founding member of a set of proteins required for high capacity mitochondrial calcium entry. Its discovery may lead to the complete molecular characterization of mitochondrial calcium uptake pathways, and offers genetic strategies for understanding their contribution to normal physiology and disease.
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24
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Drobac E, Tricoire L, Chaffotte AF, Guiot E, Lambolez B. Calcium imaging in single neurons from brain slices using bioluminescent reporters. J Neurosci Res 2010; 88:695-711. [PMID: 19798746 DOI: 10.1002/jnr.22249] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Responses of three bioluminescent Ca(2+) sensors were studied in vitro and in neurons from brain slices. These sensors consisted of tandem fusions of green fluorescent protein (GFP) with the photoproteins aequorin, obelin, or a mutant aequorin with high Ca(2+) sensitivity. Kinetics of GFP-obelin responses to a saturating Ca(2+) concentration were faster than those of GFP-aequorin at all Mg(2+) concentrations tested, whereas GFP-mutant aequorin responses were the slowest. GFP-photoproteins were efficiently expressed in pyramidal neurons following overnight incubation of acute neocortical slices with recombinant Sindbis viruses. Expression of GFP-photoproteins did not result in conspicuous modification of morphological or electrophysiological properties of layer V pyramidal cells. The three sensors allowed the detection of Ca(2+) transients associated with action potential discharge in single layer V pyramidal neurons. In these neurons, depolarizing steps of increasing amplitude elicited action potential discharge of increasing frequency. Bioluminescent responses of the three sensors were similar in several respects: detection thresholds, an exponential increase with stimulus intensity, photoprotein consumptions, and kinetic properties. These responses, which were markedly slower than kinetics measured in vitro, increased linearly during the action potential discharge and decayed exponentially at the end of the discharge. Onset slopes increased with stimulus intensity, whereas decay kinetics remained constant. Dendritic light emission contributed to whole-field responses, but the spatial resolution of bioluminescence imaging was limited to the soma and proximal apical dendrite. Nonetheless, the high signal-to-background ratio of GFP-photoproteins allowed the detection of Ca(2+) transients associated with 5 action potentials in single neurons upon whole-field bioluminescence recordings.
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Affiliation(s)
- Estelle Drobac
- Université Pierre et Marie Curie-Paris 6, Neurobiologie des Processus Adaptatifs, CNRS UMR 7102, Paris, France
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25
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Pozzan T, Rudolf R. Measurements of mitochondrial calcium in vivo. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2009; 1787:1317-23. [DOI: 10.1016/j.bbabio.2008.11.012] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2008] [Revised: 11/20/2008] [Accepted: 11/21/2008] [Indexed: 12/21/2022]
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26
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Moscatiello R, Alberghini S, Squartini A, Mariani P, Navazio L. Evidence for calcium-mediated perception of plant symbiotic signals in aequorin-expressing Mesorhizobium loti. BMC Microbiol 2009; 9:206. [PMID: 19775463 PMCID: PMC2759959 DOI: 10.1186/1471-2180-9-206] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2009] [Accepted: 09/23/2009] [Indexed: 11/22/2022] Open
Abstract
Background During the interaction between rhizobia and leguminous plants the two partners engage in a molecular conversation that leads to reciprocal recognition and ensures the beginning of a successful symbiotic integration. In host plants, intracellular Ca2+ changes are an integral part of the signalling mechanism. In rhizobia it is not yet known whether Ca2+ can act as a transducer of symbiotic signals. Results A plasmid encoding the bioluminescent Ca2+ probe aequorin was introduced into Mesorhizobium loti USDA 3147T strain to investigate whether a Ca2+ response is activated in rhizobia upon perception of plant root exudates. We find that M. loti cells respond to environmental and symbiotic cues through transient elevations in intracellular free Ca2+ concentration. Only root exudates from the homologous host Lotus japonicus induce Ca2+ signalling and downstream activation of nodulation genes. The extracellular Ca2+ chelator EGTA inhibits both transient intracellular Ca2+ increase and inducible nod gene expression, while not affecting the expression of other genes, either constitutively expressed or inducible. Conclusion These findings indicate a newly described early event in the molecular dialogue between plants and rhizobia and highlight the use of aequorin-expressing bacterial strains as a promising novel approach for research in legume symbiosis.
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Affiliation(s)
- Roberto Moscatiello
- Dipartimento di Biologia, Università di Padova, Via U, Bassi 58/B, 35131 Padova, Italy.
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27
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Fahrner M, Muik M, Derler I, Schindl R, Fritsch R, Frischauf I, Romanin C. Mechanistic view on domains mediating STIM1-Orai coupling. Immunol Rev 2009; 231:99-112. [DOI: 10.1111/j.1600-065x.2009.00815.x] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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28
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Sorgato MC, Bertoli A. From cell protection to death: May Ca2+ signals explain the chameleonic attributes of the mammalian prion protein? Biochem Biophys Res Commun 2009; 379:171-4. [DOI: 10.1016/j.bbrc.2008.12.026] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2008] [Accepted: 12/08/2008] [Indexed: 11/26/2022]
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29
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Brini M. Calcium-sensitive photoproteins. Methods 2008; 46:160-6. [DOI: 10.1016/j.ymeth.2008.09.011] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2008] [Accepted: 09/12/2008] [Indexed: 12/28/2022] Open
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McCombs JE, Palmer AE. Measuring calcium dynamics in living cells with genetically encodable calcium indicators. Methods 2008; 46:152-9. [PMID: 18848629 DOI: 10.1016/j.ymeth.2008.09.015] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2008] [Accepted: 09/12/2008] [Indexed: 01/25/2023] Open
Abstract
Genetically encoded calcium indicators (GECIs) allow researchers to measure calcium dynamics in specific targeted locations within living cells. Such indicators enable dissection of the spatial and temporal control of calcium signaling processes. Here we review recent progress in the development of GECIs, highlighting which indicators are most appropriate for measuring calcium in specific organelles and localized domains in mammalian tissue culture cells. An overview of recent approaches that have been undertaken to ensure that the GECIs are minimally perturbed by the cellular environment is provided. Additionally, the procedures for introducing GECIs into mammalian cells, conducting calcium imaging experiments, and analyzing data are discussed. Because organelle-targeted indicators often pose an additional challenge, we underscore strategies for calibrating GECIs in these locations.
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Affiliation(s)
- Janet E McCombs
- Department of Chemistry and Biochemistry, University of Colorado, UCB 215, 76 Chemistry, Boulder, CO 80309-0215, USA
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31
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Brandman O, Liou J, Park WS, Meyer T. STIM2 is a feedback regulator that stabilizes basal cytosolic and endoplasmic reticulum Ca2+ levels. Cell 2008; 131:1327-39. [PMID: 18160041 DOI: 10.1016/j.cell.2007.11.039] [Citation(s) in RCA: 549] [Impact Index Per Article: 34.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2007] [Revised: 10/02/2007] [Accepted: 11/15/2007] [Indexed: 01/10/2023]
Abstract
Deviations in basal Ca2+ levels interfere with receptor-mediated Ca2+ signaling as well as endoplasmic reticulum (ER) and mitochondrial function. While defective basal Ca2+ regulation has been linked to various diseases, the regulatory mechanism that controls basal Ca2+ is poorly understood. Here we performed an siRNA screen of the human signaling proteome to identify regulators of basal Ca2+ concentration and found STIM2 as the strongest positive regulator. In contrast to STIM1, a recently discovered signal transducer that triggers Ca2+ influx in response to receptor-mediated depletion of ER Ca2+ stores, STIM2 activated Ca2+ influx upon smaller decreases in ER Ca2+. STIM2, like STIM1, caused Ca2+ influx via activation of the plasma membrane Ca2+ channel Orai1. Our study places STIM2 at the center of a feedback module that keeps basal cytosolic and ER Ca2+ concentrations within tight limits.
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Affiliation(s)
- Onn Brandman
- Department of Chemical and Systems Biology, Bio-X/Clark Center W200, Stanford University, Stanford, CA 94305, USA.
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32
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Garcia CRS, de Azevedo MF, Wunderlich G, Budu A, Young JA, Bannister L. Plasmodium in the postgenomic era: new insights into the molecular cell biology of malaria parasites. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2008; 266:85-156. [PMID: 18544493 DOI: 10.1016/s1937-6448(07)66003-1] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
In this review, we bring together some of the approaches toward understanding the cellular and molecular biology of Plasmodium species and their interaction with their host red blood cells. Considerable impetus has come from the development of new methods of molecular genetics and bioinformatics, and it is important to evaluate the wealth of these novel data in the context of basic cell biology. We describe how these approaches are gaining valuable insights into the parasite-host cell interaction, including (1) the multistep process of red blood cell invasion by the merozoite; (2) the mechanisms by which the intracellular parasite feeds on the red blood cell and exports parasite proteins to modify its cytoadherent properties; (3) the modulation of the cell cycle by sensing the environmental tryptophan-related molecules; (4) the mechanism used to survive in a low Ca(2+) concentration inside red blood cells; (5) the activation of signal transduction machinery and the regulation of intracellular calcium; (6) transfection technology; and (7) transcriptional regulation and genome-wide mRNA studies in Plasmodium falciparum.
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Affiliation(s)
- Celia R S Garcia
- Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, CEP 05508-900, São Paulo, SP, Brazil
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33
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Qu X, Deo SK, Dikici E, Ensor M, Poon M, Daunert S. Bioluminescence immunoassay for angiotensin II using aequorin as a label. Anal Biochem 2007; 371:154-61. [PMID: 17931588 DOI: 10.1016/j.ab.2007.08.038] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2007] [Revised: 08/29/2007] [Accepted: 08/30/2007] [Indexed: 10/22/2022]
Abstract
Angiotensin II is a biologically active component of the renin-angiotensin system. High levels of angiotensin II may be responsible for hypertension and heart failure because they increase systemic vascular resistance, arterial pressure, and sodium and fluid retention. Therefore, it is important to monitor angiotensin II levels for the treatment of hypertension and heart diseases. The goal of this work was to develop a bioluminescence immunoassay using aequorin as a label to measure angiotensin II levels in human plasma. This method utilizes a genetically engineered fusion protein between angiotensin II and aequorin. For that, the C terminus of angiotensin II was fused to the N terminus of apoaequorin using molecular biology techniques. A heterogeneous immunoassay was then developed for the determination of angiotensin II. A detection limit of 1 pg/mL was obtained with the optimized assay, allowing for the determination of angiotensin II at physiological levels in human plasma.
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Affiliation(s)
- Xiaoge Qu
- Department of Chemistry, University of Kentucky, Lexington, KY 40506, U.S.A
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Rapizzi E, Donati C, Cencetti F, Pinton P, Rizzuto R, Bruni P. Sphingosine 1-phosphate receptors modulate intracellular Ca2+ homeostasis. Biochem Biophys Res Commun 2007; 353:268-74. [PMID: 17184732 DOI: 10.1016/j.bbrc.2006.12.010] [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: 11/24/2006] [Accepted: 12/01/2006] [Indexed: 11/20/2022]
Abstract
Ligation of sphingosine 1-phosphate (S1P) to a set of specific receptors named S1P receptors (S1PRs) regulates important biological processes. Although the ability of S1P to increase cytosolic Ca2+ in various cell types is well known, the role of the individual S1PRs has not been fully characterized. Here, we provide a complete analysis of S1P-dependent intracellular Ca2+ homeostasis in HeLa cells. Overexpression of S1P2, or S1P3, but not S1P1, leads to a significant increase in cytosolic and mitochondrial [Ca2+] in response to S1P challenge. Moreover, cells ectopically expressing S1P2, or S1P3 exhibited an appreciable decrease of the free Ca2+ concentration in the endoplasmic reticulum, dependent on stimulation of receptors by S1P endogenously present in the culture medium which was accompanied by a reduced susceptibility to C2-ceramide-induced cell death. These results demonstrate a differential contribution of individual S1PRs to Ca2+ homeostasis and its possible implication in the regulation of cell survival.
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Affiliation(s)
- Elena Rapizzi
- Department of Biochemical Sciences, Istituto Interuniversitario di Miologia (IIM), University of Firenze, 44100 Firenze, Italy
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35
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García AG, García-De-Diego AM, Gandía L, Borges R, García-Sancho J. Calcium Signaling and Exocytosis in Adrenal Chromaffin Cells. Physiol Rev 2006; 86:1093-131. [PMID: 17015485 DOI: 10.1152/physrev.00039.2005] [Citation(s) in RCA: 259] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
At a given cytosolic domain of a chromaffin cell, the rate and amplitude of the Ca2+concentration ([Ca2+]c) depends on at least four efficient regulatory systems: 1) plasmalemmal calcium channels, 2) endoplasmic reticulum, 3) mitochondria, and 4) chromaffin vesicles. Different mammalian species express different levels of the L, N, P/Q, and R subtypes of high-voltage-activated calcium channels; in bovine and humans, P/Q channels predominate, whereas in felines and murine species, L-type channels predominate. The calcium channels in chromaffin cells are regulated by G proteins coupled to purinergic and opiate receptors, as well as by voltage and the local changes of [Ca2+]c. Chromaffin cells have been particularly useful in studying calcium channel current autoregulation by materials coreleased with catecholamines, such as ATP and opiates. Depending on the preparation (cultured cells, adrenal slices) and the stimulation pattern (action potentials, depolarizing pulses, high K+, acetylcholine), the role of each calcium channel in controlling catecholamine release can change drastically. Targeted aequorin and confocal microscopy shows that Ca2+entry through calcium channels can refill the endoplasmic reticulum (ER) to nearly millimolar concentrations, and causes the release of Ca2+(CICR). Depending on its degree of filling, the ER may act as a sink or source of Ca2+that modulates catecholamine release. Targeted aequorins with different Ca2+affinities show that mitochondria undergo surprisingly rapid millimolar Ca2+transients, upon stimulation of chromaffin cells with ACh, high K+, or caffeine. Physiological stimuli generate [Ca2+]cmicrodomains in which the local subplasmalemmal [Ca2+]crises abruptly from 0.1 to ∼50 μM, triggering CICR, mitochondrial Ca2+uptake, and exocytosis at nearby secretory active sites. The fact that protonophores abolish mitochondrial Ca2+uptake, and increase catecholamine release three- to fivefold, support the earlier observation. This increase is probably due to acceleration of vesicle transport from a reserve pool to a ready-release vesicle pool; this transport might be controlled by Ca2+redistribution to the cytoskeleton, through CICR, and/or mitochondrial Ca2+release. We propose that chromaffin cells have developed functional triads that are formed by calcium channels, the ER, and the mitochondria and locally control the [Ca2+]cthat regulate the early and late steps of exocytosis.
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Affiliation(s)
- Antonio G García
- Instituto Teófilo Hernando, Departamento de Farmacología y Terapéutica, and Servicio de Farmacología Clínica e Instituto Universitario de Investigación Gerontológica y Metabólica, Hospital Universitario de la Princesa, Madrid, Spain.
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Tricoire L, Tsuzuki K, Courjean O, Gibelin N, Bourout G, Rossier J, Lambolez B. Calcium dependence of aequorin bioluminescence dissected by random mutagenesis. Proc Natl Acad Sci U S A 2006; 103:9500-5. [PMID: 16769886 PMCID: PMC1480436 DOI: 10.1073/pnas.0603176103] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Aequorin bioluminescence is emitted as a rapidly decaying flash upon calcium binding. Random mutagenesis and functional screening were used to isolate aequorin mutants showing slow decay rate of luminescence. Calcium sensitivity curves were shifted in all mutants, and an intrinsic link between calcium sensitivity and decay rate was suggested by the position of all mutations in or near EF-hand calcium-binding sites. From these results, a low calcium affinity was assigned to the N-terminal EF hand and a high affinity to the C-terminal EF-hand pair. In WT aequorin, the increase of the decay rate with calcium occurred at constant total photon yield and thus determined a corresponding increase of light intensity. Increase of the decay rate was underlain by variations of a fast and a slow component and required the contribution of all three EF hands. Conversely, analyses of double EF-hand mutants suggested that single EF hands are sufficient to trigger luminescence at a slow rate. Finally, a model postulating that proportions of a fast and a slow light-emitting state depend on calcium concentration adequately described the calcium dependence of aequorin bioluminescence. Our results suggest that variations of luminescence kinetics, which depend on three EF hands endowed with different calcium affinities, critically determine the amplitude of aequorin responses to biological calcium signals.
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Affiliation(s)
- Ludovic Tricoire
- Laboratoire de Neurobiologie et Diversité Cellulaire, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7637, Ecole Supérieure de Physique et de Chimie Industrielles, 10 Rue Vauquelin, 75005 Paris, France
| | - Keisuke Tsuzuki
- Laboratoire de Neurobiologie et Diversité Cellulaire, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7637, Ecole Supérieure de Physique et de Chimie Industrielles, 10 Rue Vauquelin, 75005 Paris, France
| | - Olivier Courjean
- Laboratoire de Neurobiologie et Diversité Cellulaire, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7637, Ecole Supérieure de Physique et de Chimie Industrielles, 10 Rue Vauquelin, 75005 Paris, France
| | - Nathalie Gibelin
- Laboratoire de Neurobiologie et Diversité Cellulaire, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7637, Ecole Supérieure de Physique et de Chimie Industrielles, 10 Rue Vauquelin, 75005 Paris, France
| | - Gaëlle Bourout
- Laboratoire de Neurobiologie et Diversité Cellulaire, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7637, Ecole Supérieure de Physique et de Chimie Industrielles, 10 Rue Vauquelin, 75005 Paris, France
| | - Jean Rossier
- Laboratoire de Neurobiologie et Diversité Cellulaire, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7637, Ecole Supérieure de Physique et de Chimie Industrielles, 10 Rue Vauquelin, 75005 Paris, France
| | - Bertrand Lambolez
- Laboratoire de Neurobiologie et Diversité Cellulaire, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7637, Ecole Supérieure de Physique et de Chimie Industrielles, 10 Rue Vauquelin, 75005 Paris, France
- To whom correspondence should be addressed. E-mail:
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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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Tsuzuki K, Tricoire L, Courjean O, Gibelin N, Rossier J, Lambolez B. Thermostable Mutants of the Photoprotein Aequorin Obtained by in Vitro Evolution. J Biol Chem 2005; 280:34324-31. [PMID: 15972815 DOI: 10.1074/jbc.m505303200] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Aequorin is a photoprotein that emits light upon binding calcium. Aequorin mutants showing increased intensity or slow decay of bioluminescence were isolated by in vitro evolution combining DNA shuffling and functional screening in bacteria. Luminescence decay mutants were isolated at the first round of screening and carried mutations located in EF-hand calcium binding sites or their vicinity. During in vitro evolution, the luminescence intensity of the population of mutants increased with the frequency of effective mutations whereas the frequency of other amino acid substitutions remained roughly stable. Luminescence intensity mutations neighbored the His-16 or His-169 coelenterazine binding residues or were located in the first EF-hand. None of the selected mutants exhibited an increase in photon yield when examined in a cell-free assay. However, we observed that two mutants, Q168R and L170I, exhibited an increase of the photoprotein lifetime at 37 degrees C that may underlie their high luminescence intensity in bacteria. Further analysis of Q168R and L170I mutations showed that they increased aequorin thermostability. Conversely, examination of luminescence decay mutants revealed that the F149S substitution decreased aequorin thermostability. Finally, screening of a library of random Gln-168 and Leu-170 mutants confirmed the involvement of both positions in thermostability and indicated that optimal thermostability was conferred by Q168R and L170I mutations selected through in vitro evolution. Our results suggest that Phe-149 and Gln-168 residues participate in stabilization of the coelenterazine peroxide and the triggering of photon emission by linking the third EF-hand to Trp-129 and His-169 coelenterazine binding residues.
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Affiliation(s)
- Keisuke Tsuzuki
- Laboratoire de Neurobiologie et Diversité Cellulaire, CNRS UMR 7637, Ecole Supérieure de Physique et de Chimie Industrielles, 75005 Paris, France
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Rogers KL, Stinnakre J, Agulhon C, Jublot D, Shorte SL, Kremer EJ, Brûlet P. Visualization of local Ca2+ dynamics with genetically encoded bioluminescent reporters. Eur J Neurosci 2005; 21:597-610. [PMID: 15733079 DOI: 10.1111/j.1460-9568.2005.03871.x] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Measurements of local Ca2+ signalling at different developmental stages and/or in specific cell types is important for understanding aspects of brain functioning. The use of light excitation in fluorescence imaging can cause phototoxicity, photobleaching and auto-fluorescence. In contrast, bioluminescence does not require the input of radiative energy and can therefore be measured over long periods, with very high temporal resolution. Aequorin is a genetically encoded Ca(2+)-sensitive bioluminescent protein, however, its low quantum yield prevents dynamic measurements of Ca2+ responses in single cells. To overcome this limitation, we recently reported the bi-functional Ca2+ reporter gene, GFP-aequorin (GA), which was developed specifically to improve the light output and stability of aequorin chimeras [V. Baubet, et al., (2000) PNAS, 97, 7260-7265]. In the current study, we have genetically targeted GA to different microdomains important in synaptic transmission, including to the mitochondrial matrix, endoplasmic reticulum, synaptic vesicles and to the postsynaptic density. We demonstrate that these reporters enable 'real-time' measurements of subcellular Ca2+ changes in single mammalian neurons using bioluminescence. The high signal-to-noise ratio of these reporters is also important in that it affords the visualization of Ca2+ dynamics in cell-cell communication in neuronal cultures and tissue slices. Further, we demonstrate the utility of this approach in ex-vivo preparations of mammalian retina, a paradigm in which external light input should be controlled. This represents a novel molecular imaging approach for non-invasive monitoring of local Ca2+ dynamics and cellular communication in tissue or whole animal studies.
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Affiliation(s)
- Kelly L Rogers
- Unité d'Embryologie Moléculaire, CNRS URA 2578, Institut Pasteur, 25-28 rue du Docteur Roux, 75724 Paris CEDEX 15, France
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Palmer AE, Jin C, Reed JC, Tsien RY. Bcl-2-mediated alterations in endoplasmic reticulum Ca2+ analyzed with an improved genetically encoded fluorescent sensor. Proc Natl Acad Sci U S A 2004; 101:17404-9. [PMID: 15585581 PMCID: PMC535104 DOI: 10.1073/pnas.0408030101] [Citation(s) in RCA: 509] [Impact Index Per Article: 25.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The endoplasmic reticulum (ER) serves as a cellular storehouse for Ca(2+), and Ca(2+) released from the ER plays a role in a host of critical signaling reactions, including exocytosis, contraction, metabolism, regulation of transcription, fertilization, and apoptosis. Given the central role played by the ER, our understanding of these signaling processes could be greatly enhanced by the ability to image [Ca(2+)](ER) directly in individual cells. We created a genetically encoded Ca(2+) indicator by redesigning the binding interface of calmodulin and a calmodulin-binding peptide. The sensor has improved reaction kinetics and a K(d) ideal for imaging Ca(2+) in the ER and is no longer perturbed by large excesses of native calmodulin. Importantly, it provides a significant improvement over all previous methods for monitoring [Ca(2+)](ER) and has been used to directly show that, in MCF-7 breast cancer cells, the antiapoptotic protein B cell lymphoma 2 (Bcl-2) (i) lowers [Ca(2+)](ER) by increasing Ca(2+) leakage under resting conditions and (ii) alters Ca(2+) oscillations induced by ATP, and that acute inhibition of Bcl-2 by the green tea compound epigallocatechin gallate results in an increase in [Ca(2+)](ER) due to inhibition of Bcl-2-mediated Ca(2+) leakage.
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Affiliation(s)
- Amy E Palmer
- Department of Pharmacology and Howard Hughes Medical Institute, University of California at San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0647, USA
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Basset O, Boittin FX, Dorchies OM, Chatton JY, van Breemen C, Ruegg UT. Involvement of Inositol 1,4,5-Trisphosphate in Nicotinic Calcium Responses in Dystrophic Myotubes Assessed by Near-plasma Membrane Calcium Measurement. J Biol Chem 2004; 279:47092-100. [PMID: 15322099 DOI: 10.1074/jbc.m405054200] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In skeletal muscle cells, plasma membrane depolarization causes a rapid calcium release from the sarcoplasmic reticulum through ryanodine receptors triggering contraction. In Duchenne muscular dystrophy (DMD), a lethal disease that is caused by the lack of the cytoskeletal protein dystrophin, the cytosolic calcium concentration is known to be increased, and this increase may lead to cell necrosis. Here, we used myotubes derived from control and mdx mice, the murine model of DMD, to study the calcium responses induced by nicotinic acetylcholine receptor stimulation. The photoprotein aequorin was expressed in the cytosol or targeted to the plasma membrane as a fusion protein with the synaptosome-associated protein SNAP-25, thus allowing calcium measurements in a restricted area localized just below the plasma membrane. The carbachol-induced calcium responses were 4.5 times bigger in dystrophic myotubes than in control myotubes. Moreover, in dystrophic myotubes the carbachol-mediated calcium responses measured in the subsarcolemmal area were at least 10 times bigger than in the bulk cytosol. The initial calcium responses were due to calcium influx into the cells followed by a fast refilling/release phase from the sarcoplasmic reticulum. In addition and unexpectedly, the inositol 1,4,5-trisphosphate receptor pathway was involved in these calcium signals only in the dystrophic myotubes. This surprising involvement of this calcium release channel in the excitation-contraction coupling could open new ways for understanding exercise-induced calcium increases and downstream muscle degeneration in mdx mice and, therefore, in DMD.
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Affiliation(s)
- Olivier Basset
- Pharmacology Laboratory, School of Pharmacy, University of Lausanne-Geneva, 1211 Geneva, Switzerland
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Mahapatra NR, Mahata M, Hazra PP, McDonough PM, O'Connor DT, Mahata SK. A dynamic pool of calcium in catecholamine storage vesicles. Exploration in living cells by a novel vesicle-targeted chromogranin A-aequorin chimeric photoprotein. J Biol Chem 2004; 279:51107-21. [PMID: 15358782 DOI: 10.1074/jbc.m408742200] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Chromaffin vesicles contain very high concentration of Ca2+ (approximately 20-40 mM total), compared with approximately 100 nM in the cytosol. Aequorin, a jellyfish photoprotein with Ca(2+)-dependent luminescence, measures [Ca2+] in specific subcellular compartments wherein proteins with organelle-specific trafficking domains are fused in-frame to aequorin. Because of the presence of vesicular trafficking domain within CgA we engineered sorting of an expressed human CgA-Aequorin fusion protein (hCgA-Aeq) into the vesicle compartment as confirmed by sucrose density gradients and confocal immunofluorescent co-localization studies. hCgA-Aeq and cytoplasmic aequorin (Cyto-Aeq) luminescence displayed linear functions of [Ca2+] in vitro, over >5 log10 orders of magnitude (r > 0.99), and down to at least 10(-7) M sensitivity. Calibrating the pH dependence of hCgA-Aeq luminescence allowed estimation of [Ca2+]ves at granule interior pH (approximately 5.5). In the cytoplasm, Cyto-Aeq accurately determined [Ca2+]cyto under both basal ([Ca2+]cyto = 130 +/- 35 nM) and exocytosis-stimulated conditions, confirmed by an independent reference technique (Indo-1 fluorescence). The hCgA-Aeq chimera determined vesicular free [Ca2+]ves = 1.4 +/- 0.3 microM under basal conditions indicating that >99% of granule total Ca2+ is in a "bound" state. The basal free [Ca2+]ves/[Ca2+]cyto ratio was thus approximately 10.8-fold, indicating active, dynamic Ca2+ uptake from cytosol into the granules. Stimulation of exocytotic secretion revealed prompt, dynamic increases in both [Ca2+](ves) and [Ca2+]cyto, and an exponential relation between the two (y = 0.99 x e(1.53x), r = 0.99), reflecting a persistent [Ca2+]ves/[Ca2+]cyto gradient, even during sharp increments of both values. Studies with inhibitors of Ca2+ translocation (Ca(2+)-ATPase), Na+/Ca(+)-exchange, Na+/H(+)-exchange, and vesicle acidification (H(+)-translocating ATPase), documented a role for these four ion transporter classes in accumulation of Ca2+ inside the vesicles.
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Affiliation(s)
- Nitish R Mahapatra
- Department of Medicine, University of California, San Diego, La Jolla 92093-0838, USA
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Chan C, Harland ML, Webb SE, Chen J, Miller AL, Barritt GJ. Evaluation, using targeted aequorins, of the roles of the endoplasmic reticulum and its (Ca2++Mg2+)ATP-ases in the activation of store-operated Ca2+ channels in liver cells. Cell Calcium 2004; 35:317-31. [PMID: 15036949 DOI: 10.1016/j.ceca.2003.09.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2002] [Revised: 08/11/2003] [Accepted: 09/05/2003] [Indexed: 11/20/2022]
Abstract
The process by which store-operated Ca2+ channels (SOCs) deliver Ca2+ to the endoplasmic reticulum (ER) and the role of (Ca2++Mg2+)ATP-ases of the ER in the activation of SOCs in H4-IIE liver cells were investigated using cell lines stably transfected with apo-aequorin targeted to the cytoplasmic space or the ER. In order to measure the concentration of Ca2+ in the ER ([Ca2+]er), cells were pre-treated with 2,5-di-tert-butylhydroquinone (DBHQ) to deplete Ca2+ in the ER before reconstitution of holo-aequorin. The addition of extracellular Ca2+ (Cao2+) to Ca2+-depleted cells induced refilling of the ER, which was complete within 5 min. This was associated with a sharp transient increase in the cytoplasmic Ca2+ concentration ([Ca2+]cyt) of about 15 s duration (a Cao2+-induced [Ca2+]cyt spike) after which [Ca2+]cyt remained elevated slightly above the basal value for a period of about 2 min (low [Ca2+]cyt plateau). The Cao2+-induced [Ca2+]cyt spike was inhibited by Gd3+, not affected by tetrakis-(2-pyridymethyl) ethylenediamine (TPEN), and broadened by ionomycin and the intracellular Ca2+ chelators BAPTA and EGTA. Refilling of the ER was inhibited by caffeine. Neither thapsigargin nor DBHQ caused a detectable inhibition or change in shape of the Cao2+-induced [Ca2+]cyt spike or the low [Ca2+]cyt plateau whereas each inhibited the inflow of Ca2+ to the ER by about 80%. Experiments conducted with carbonyl cyanide m-chlorophenyl-hydrazone (CCCP) indicated that thapsigargin did not alter the amount of Ca2+ accumulated in mitochondria. The changes in [Ca2+]cyt reported by aequorin were compared with those reported by fura-2. It is concluded that (i) there are significant quantitative differences between the manner in which aequorin and fura-2 sense changes in [Ca2+]cyt and (ii) thapsigargin and DBHQ inhibit the uptake of Ca2+ to the bulk of the ER but this is not associated with inhibition of the activation of SOCs. The possible involvement of a small sub-region of the ER (or another intracellular Ca2+ store), which contains thapsigargin-insensitive (Ca2++Mg2+)ATP-ases, in the activation of SOCs is briefly discussed.
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Affiliation(s)
- Caroline Chan
- Department of Biology, The Hong Kong University of Science & Technology, Clear Water Bay, Kowloon, Hong Kong, China
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45
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Chami M, Ferrari D, Nicotera P, Paterlini-Bréchot P, Rizzuto R. Caspase-dependent alterations of Ca2+ signaling in the induction of apoptosis by hepatitis B virus X protein. J Biol Chem 2003; 278:31745-55. [PMID: 12799372 DOI: 10.1074/jbc.m304202200] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
The hepatitis B virus X protein (HBx) is a multifunctional protein, acting on different targets (e.g. transcription factors, cytoplasmic kinases, and mitochondrial proteins) and exerting cellular effects as diverse as stimulation of cell proliferation and apoptosis. In its biological effects, the modulation of cellular Ca2+ signals has been proposed to be involved, but the direct assessment of Ca2+ homeostasis in HBx-transfected cells has not been carried out yet. In this work, we have employed for this purpose aequorin-based recombinant probes specifically targeted to intracellular organelles and microdomains. Using these probes, we observed that overexpression of HBx enhanced agonist-evoked cytosolic Ca2+ signals in HepG2 and HeLa cells, without affecting either the steady state of endoplasmic reticulum Ca2+ concentration or the kinetics of Ca2+ release. Rather, caspase-3-dependent cleavage of the plasma membrane Ca2+ ATPase could be demonstrated, and larger rises were detected in the cytoplasmic rim beneath the plasma membrane. In mitochondria, major morphological (fragmentation and swelling) and functional (reduced Ca2+ uptake) alterations were detected in HBx-expressing cells. As to the cellular consequences, we observed that HBx-induced apoptosis was markedly reduced when the alterations in Ca2+ signaling (e.g. by loading a Ca2+ chelator or preventing PMCA cleavage) or the downstream effects (e.g. by inhibiting mitochondrial permeability transition) were prevented. Overall, these results indicate that HBx perturbs intracellular Ca2+ homeostasis, acting on the extrusion mechanisms, and that this effect plays an important role in the control of HBx-related apoptosis.
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Affiliation(s)
- Mounia Chami
- Department of Experimental and Diagnostic Medicine, Section of General Pathology and Interdiscipliny Center for the Study of Inflammation, Via Borsari 46, I-44100 Ferrara, Italy
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Abstract
Consider a hypothetical design specification for an integrated communication-control system within an embryo. It would require short-range (subcellular) and long-range (pan-embryonic) abilities, it would have to be flexible and, at the same time, robust enough to operate in a dynamically changing environment without information being lost or misinterpreted. Although many signalling elements appear, disappear and sometimes reappear during development, it is becoming clear that embryos also depend on a ubiquitous, persistent and highly versatile signalling system that is based around a single messenger, Ca2+.
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Affiliation(s)
- Sarah E Webb
- Department of Biology, The Hong Kong University of Science & Technology, Clear Water Bay, Kowloon, Hong Kong SAR, PRC
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Pozzan T, Mongillo M, Rudolf R. The Theodore Bücher lecture. Investigating signal transduction with genetically encoded fluorescent probes. EUROPEAN JOURNAL OF BIOCHEMISTRY 2003; 270:2343-52. [PMID: 12755688 DOI: 10.1046/j.1432-1033.2003.03615.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Ca2+ and cAMP are ubiquitous second messengers in eukaryotes and control numerous physiological responses ranging from fertilization to cell death induction. To distinguish between these different responses, their subtle regulation in time, space and amplitude is needed. Therefore, the characterization of the signalling process requires measurement of second messengers with tools of precise localization, high dynamic range and as little disturbance of cell physiology as possible. Recently, fluorescent proteins of marine jellyfish have given rise to a set of genetically encoded biosensors which fulfil these criteria and which have already led to important new insights into the subcellular handling of Ca2+ and cAMP. The use of these probes in combination with new microscopical methods such as two-photon microscopy now enables researchers to study second messenger signalling in intact tissues. In this review, the genetically encoded measurement probes and their origin are briefly introduced and some recent insights into the spatio-temporal complexity of both Ca2+ and cAMP signalling obtained with these tools are discussed.
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Affiliation(s)
- Tullio Pozzan
- Department of Biomedical Sciences, CNR Institute of Neurosciences, University of Padua, and Venetian Institute for Molecular Medicine, Padua, Italy.
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Kiselyov K, Shin DM, Luo X, Ko SBH, Muallem S. Ca2+ signaling in polarized exocrine cells. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2003; 506:175-83. [PMID: 12613905 DOI: 10.1007/978-1-4615-0717-8_23] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/01/2023]
Affiliation(s)
- Kirill Kiselyov
- Department of Physiology, UT Southwestern Medical Center, Dallas, Texas, USA
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Mithöfer A, Mazars C. Aequorin-based measurements of intracellular Ca2+-signatures in plant cells. Biol Proced Online 2002; 4:105-118. [PMID: 12734562 PMCID: PMC145563 DOI: 10.1251/bpo40] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2002] [Revised: 11/19/2002] [Accepted: 11/21/2002] [Indexed: 11/23/2022] Open
Abstract
Due to the involvement of calcium as a main second messenger in the plant signaling pathway, increasing interest has been focused on the calcium signatures supposed to be involved in the patterning of the specific response associated to a given stimulus. In order to follow these signatures we described here the practical approach to use the non-invasive method based on the aequorin technology. Besides reviewing the advantages and disadvantages of this method we report on results showing the usefulness of aequorin to study the calcium response to biotic (elicitors) and abiotic stimuli (osmotic shocks) in various compartments of plant cells such as cytosol and nucleus.
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Affiliation(s)
- Axel Mithöfer
- Department Biologie I der Ludwig-Maximilians-Universität, Botanik. Menzinger Str. 67, D-80638, München. Germany.Signaux et Messages Cellulaires chez les Végétaux, UMR CNRS/UPS 5546. 24 Chemin de Borde Rouge, BP 17 Auzeville, F-31326 Castanet-Tolosan. France.
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Brini M, Manni S, Carafoli E. A study of the activity of the plasma membrane Na/Ca exchanger in the cellular environment. Ann N Y Acad Sci 2002; 976:376-81. [PMID: 12502584 DOI: 10.1111/j.1749-6632.2002.tb04764.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The Na/Ca exchanger is a large-capacity system that is supposed to be predominant in the ejection of calcium in excitable tissues. Its activity is normally evaluated in electro-physiological experiments or using Na-loaded cells or plasma membrane vesicles in experiments in which the activity is estimated by measuring the uptake of isotopic calcium. Here the activity of the exchanger has been evaluated in model cells that coexpress the exchanger together with the (protein) Ca indicator aequorin targeted to the different subcellular compartments. Exchanger isoform 1 (NCX1) has been used for experiments in which the effect of its overexpression has been evaluated on the Ca homeostasis in the cytoplasm at large, in the endoplasmic reticulum, in mitochondria, and in the layer of cytoplasm underneath the plasma membrane. The experiments have shown that, despite its very low calcium affinity, the exchanger was active in cells at rest in which calcium is around 100 nM. They have also shown that expressed NCX1 significantly reduced the cytosolic and mitochondrial calcium transients produced by the emptying of the ER calcium stores with InsP3-linked agonists. The effect of the expressed NCX1 on the calcium homeostasis in the domain underneath the plasma membrane was more complex: The exchanger apparently catalyzed a reverse operation, leading to increased penetration of calcium.
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Affiliation(s)
- Marisa Brini
- Department of Biochemistry and Venetian Institute of Molecular Medicine, University of Padova, Padova, Italy
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