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Ghosh S, Dahiya M, Kumar A, Bheri M, Pandey GK. Calcium imaging: a technique to monitor calcium dynamics in biological systems. PHYSIOLOGY AND MOLECULAR BIOLOGY OF PLANTS : AN INTERNATIONAL JOURNAL OF FUNCTIONAL PLANT BIOLOGY 2023; 29:1777-1811. [PMID: 38222278 PMCID: PMC10784449 DOI: 10.1007/s12298-023-01405-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2023] [Revised: 12/07/2023] [Accepted: 12/11/2023] [Indexed: 01/16/2024]
Abstract
Calcium ion (Ca2+) is a multifaceted signaling molecule that acts as an important second messenger. During the course of evolution, plants and animals have developed Ca2+ signaling in order to respond against diverse stimuli, to regulate a large number of physiological and developmental pathways. Our understanding of Ca2+ signaling and its components in physiological phenomena ranging from lower to higher organisms, and from single cell to multiple tissues has grown exponentially. The generation of Ca2+ transients or signatures for various stress factor is a well-known mechanism adopted in plant and animal systems. However, the decoding of such remarkable signatures is an uphill task and is always an interesting goal for the scientific community. In the past few decades, studies on the concentration and dynamics of intracellular Ca2+ are significantly increasing and have become a trend in modern biology. The advancement in approaches from Ca2+ binding dyes to in vivo Ca2+ imaging through the use of Ca2+ biosensors to achieve spatio-temporal resolution in micro and milliseconds range, provide us phenomenal opportunities to study live cell Ca2+ imaging or dynamics. Here, we describe the usage, improvement and advancement of Ca2+ based dyes, genetically encoded probes and sensors to achieve extraordinary Ca2+ imaging in plants and animals. Graphical abstract
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Affiliation(s)
- Soma Ghosh
- Department of Plant Molecular Biology, University of Delhi South Campus, Benito Juarez Road, Dhaula Kuan, New Delhi, 110021 India
| | - Monika Dahiya
- Department of Plant Molecular Biology, University of Delhi South Campus, Benito Juarez Road, Dhaula Kuan, New Delhi, 110021 India
| | - Amit Kumar
- Department of Plant Molecular Biology, University of Delhi South Campus, Benito Juarez Road, Dhaula Kuan, New Delhi, 110021 India
| | - Malathi Bheri
- Department of Plant Molecular Biology, University of Delhi South Campus, Benito Juarez Road, Dhaula Kuan, New Delhi, 110021 India
| | - Girdhar K. Pandey
- Department of Plant Molecular Biology, University of Delhi South Campus, Benito Juarez Road, Dhaula Kuan, New Delhi, 110021 India
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Osterlund EJ, Hirmiz N, Nguyen D, Pemberton JM, Fang Q, Andrews DW. Endoplasmic reticulum protein BIK binds to and inhibits mitochondria-localized antiapoptotic proteins. J Biol Chem 2023; 299:102863. [PMID: 36603764 PMCID: PMC9932132 DOI: 10.1016/j.jbc.2022.102863] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Revised: 11/22/2022] [Accepted: 12/14/2022] [Indexed: 01/04/2023] Open
Abstract
The proapoptotic BCL-2 homology (BH3)-only endoplasmic reticulum (ER)-resident protein BCL-2 interacting killer (BIK) positively regulates mitochondrial outer membrane permeabilization, the point of no return in apoptosis. It is generally accepted that BIK functions at a distance from mitochondria by binding and sequestering antiapoptotic proteins at the ER, thereby promoting ER calcium release. Although BIK is predominantly localized to the ER, we detect by fluorescence lifetime imaging microscopy-FRET microscopy, BH3 region-dependent direct binding between BIK and mitochondria-localized chimeric mutants of the antiapoptotic proteins BCL-XL and BCL-2 in both baby mouse kidney (BMK) and MCF-7 cells. Direct binding was accompanied by cell type-specific differential relocalization in response to coexpression of either BIK or one of its target binding partners, BCL-XL, when coexpressed in cells. In BMK cells with genetic deletion of both BAX and BAK (BMK-double KO), our data suggest that a fraction of BIK protein moves toward mitochondria in response to the expression of a mitochondria-localized BCL-XL mutant. In contrast, in MCF-7 cells, our data suggest that BIK is localized at both ER and mitochondria-associated ER membranes and binds to the mitochondria-localized BCL-XL mutant via relocalization of BCL-XL to ER and mitochondria-associated ER membrane. Rather than functioning at a distance, our data suggest that BIK initiates mitochondrial outer membrane permeabilization via direct interactions with ER and mitochondria-localized antiapoptotic proteins, which occur via ER-mitochondria contact sites, and/or by relocalization of either BIK or antiapoptotic proteins in cells.
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Affiliation(s)
- Elizabeth J Osterlund
- Biological Sciences, Sunnybrook Research Institute, Toronto, Ontario, Canada; Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Nehad Hirmiz
- Biological Sciences, Sunnybrook Research Institute, Toronto, Ontario, Canada; School of Biomedical Engineering, McMaster University, Hamilton, Ontario, Canada
| | - Dang Nguyen
- Biological Sciences, Sunnybrook Research Institute, Toronto, Ontario, Canada; Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
| | - James M Pemberton
- Biological Sciences, Sunnybrook Research Institute, Toronto, Ontario, Canada; Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
| | - Qiyin Fang
- School of Biomedical Engineering, McMaster University, Hamilton, Ontario, Canada; Department of Engineering Physics, McMaster University, Hamilton, Ontario, Canada
| | - David W Andrews
- Biological Sciences, Sunnybrook Research Institute, Toronto, Ontario, Canada; Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada.
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Yoast RE, Emrich SM, Zhang X, Xin P, Arige V, Pathak T, Benson JC, Johnson MT, Abdelnaby AE, Lakomski N, Hempel N, Han JM, Dupont G, Yule DI, Sneyd J, Trebak M. The Mitochondrial Ca 2+ uniporter is a central regulator of interorganellar Ca 2+ transfer and NFAT activation. J Biol Chem 2021; 297:101174. [PMID: 34499925 PMCID: PMC8496184 DOI: 10.1016/j.jbc.2021.101174] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Revised: 08/31/2021] [Accepted: 09/03/2021] [Indexed: 12/12/2022] Open
Abstract
Mitochondrial Ca2+ uptake tailors the strength of stimulation of plasma membrane phospholipase C–coupled receptors to that of cellular bioenergetics. However, how Ca2+ uptake by the mitochondrial Ca2+ uniporter (MCU) shapes receptor-evoked interorganellar Ca2+ signaling is unknown. Here, we used CRISPR/Cas9 gene knockout, subcellular Ca2+ imaging, and mathematical modeling to show that MCU is a universal regulator of intracellular Ca2+ signaling across mammalian cell types. MCU activity sustains cytosolic Ca2+ signaling by preventing Ca2+-dependent inactivation of store-operated Ca2+ release–activated Ca2+ channels and by inhibiting Ca2+ extrusion. Paradoxically, MCU knockout (MCU-KO) enhanced cytosolic Ca2+ responses to store depletion. Physiological agonist stimulation in MCU-KO cells led to enhanced frequency of cytosolic Ca2+ oscillations, endoplasmic reticulum Ca2+ refilling, nuclear translocation of nuclear factor for activated T cells transcription factors, and cell proliferation, without altering inositol-1,4,5-trisphosphate receptor activity. Our data show that MCU has dual counterbalancing functions at the cytosol–mitochondria interface, whereby the cell-specific MCU-dependent cytosolic Ca2+ clearance and buffering capacity of mitochondria reciprocally regulate interorganellar Ca2+ transfer and nuclear factor for activated T cells nuclear translocation during receptor-evoked signaling. These findings highlight the critical dual function of the MCU not only in the acute Ca2+ buffering by mitochondria but also in shaping endoplasmic reticulum and cytosolic Ca2+ signals that regulate cellular transcription and function.
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Affiliation(s)
- Ryan E Yoast
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania, USA
| | - Scott M Emrich
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania, USA
| | - Xuexin Zhang
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania, USA
| | - Ping Xin
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania, USA; Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA; Vascular Medicine Institute, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Vikas Arige
- Department of Pharmacology and Physiology, University of Rochester, Rochester, New York, USA
| | - Trayambak Pathak
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania, USA; Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA; Vascular Medicine Institute, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - J Cory Benson
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania, USA; Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA; Vascular Medicine Institute, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Martin T Johnson
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania, USA
| | - Ahmed Emam Abdelnaby
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania, USA; Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA; Vascular Medicine Institute, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Natalia Lakomski
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania, USA
| | - Nadine Hempel
- Department of Pharmacology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania, USA
| | - Jung Min Han
- Laboratory of Biological Modeling, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Geneviève Dupont
- Unité de Chronobiologie Théorique, Université Libre de Bruxelles, Brussels, Belgium
| | - David I Yule
- Department of Pharmacology and Physiology, University of Rochester, Rochester, New York, USA
| | - James Sneyd
- Department of Mathematics, The University of Auckland, Auckland, New Zealand
| | - Mohamed Trebak
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania, USA; Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA; Vascular Medicine Institute, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA.
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Morciano G, Naumova N, Koprowski P, Valente S, Sardão VA, Potes Y, Rimessi A, Wieckowski MR, Oliveira PJ. The mitochondrial permeability transition pore: an evolving concept critical for cell life and death. Biol Rev Camb Philos Soc 2021; 96:2489-2521. [PMID: 34155777 DOI: 10.1111/brv.12764] [Citation(s) in RCA: 52] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Revised: 05/28/2021] [Accepted: 06/04/2021] [Indexed: 02/06/2023]
Abstract
In this review, we summarize current knowledge of perhaps one of the most intriguing phenomena in cell biology: the mitochondrial permeability transition pore (mPTP). This phenomenon, which was initially observed as a sudden loss of inner mitochondrial membrane impermeability caused by excessive calcium, has been studied for almost 50 years, and still no definitive answer has been provided regarding its mechanisms. From its initial consideration as an in vitro artifact to the current notion that the mPTP is a phenomenon with physiological and pathological implications, a long road has been travelled. We here summarize the role of mitochondria in cytosolic calcium control and the evolving concepts regarding the mitochondrial permeability transition (mPT) and the mPTP. We show how the evolving mPTP models and mechanisms, which involve many proposed mitochondrial protein components, have arisen from methodological advances and more complex biological models. We describe how scientific progress and methodological advances have allowed milestone discoveries on mPTP regulation and composition and its recognition as a valid target for drug development and a critical component of mitochondrial biology.
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Affiliation(s)
- Giampaolo Morciano
- Maria Cecilia Hospital, GVM Care & Research, Via Corriera 1, Cotignola, Ravenna, 48033, Italy.,Department of Medical Sciences, Section of Experimental Medicine, Laboratory for Technologies of Advanced Therapies (LTTA), University of Ferrara, Via Fossato di Mortara 70, Ferrara, 44121, Italy
| | - Natalia Naumova
- Department of Cardiac Thoracic and Vascular Sciences and Public Health, University of Padua Medical School, Via Giustiniani 2, Padova, 35128, Italy
| | - Piotr Koprowski
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur Street, Warsaw, 02-093, Poland
| | - Sara Valente
- CNC - Center for Neuroscience and Cell Biology, CIBB - Centre for Innovative Biomedicine and Biotechnology, University of Coimbra, UC Biotech, Biocant Park, Cantanhede, 3060-197, Portugal
| | - Vilma A Sardão
- CNC - Center for Neuroscience and Cell Biology, CIBB - Centre for Innovative Biomedicine and Biotechnology, University of Coimbra, UC Biotech, Biocant Park, Cantanhede, 3060-197, Portugal
| | - Yaiza Potes
- Laboratory of Mitochondrial Biology and Metabolism, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur Street, Warsaw, 02-093, Poland
| | - Alessandro Rimessi
- Department of Medical Sciences, Section of Experimental Medicine, Laboratory for Technologies of Advanced Therapies (LTTA), University of Ferrara, Via Fossato di Mortara 70, Ferrara, 44121, Italy
| | - Mariusz R Wieckowski
- Laboratory of Mitochondrial Biology and Metabolism, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur Street, Warsaw, 02-093, Poland
| | - Paulo J Oliveira
- CNC - Center for Neuroscience and Cell Biology, CIBB - Centre for Innovative Biomedicine and Biotechnology, University of Coimbra, UC Biotech, Biocant Park, Cantanhede, 3060-197, Portugal
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Mitochondrial junctions with cellular organelles: Ca 2+ signalling perspective. Pflugers Arch 2018; 470:1181-1192. [PMID: 29982949 PMCID: PMC6060751 DOI: 10.1007/s00424-018-2179-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Revised: 06/27/2018] [Accepted: 06/29/2018] [Indexed: 01/21/2023]
Abstract
Cellular organelles form multiple junctional complexes with one another and the emerging research area dealing with such structures and their functions is undergoing explosive growth. A new research journal named “Contact” has been recently established to facilitate the development of this research field. The current consensus is to define an organellar junction by the maximal distance between the participating organelles; and the gap of 30 nm or less is considered appropriate for classifying such structures as junctions or membrane contact sites. Ideally, the organellar junction should have a functional significance, i.e. facilitate transfer of calcium, sterols, phospholipids, iron and possibly other substances between the organelles (Carrasco and Meyer in Annu Rev Biochem 80:973–1000, 2011; Csordas et al. in Trends Cell Biol 28:523–540, 2018; Phillips and Voeltz in Nat Rev Mol Cell Biol 17:69–82, 2016; Prinz in J Cell Biol 205:759–769, 2014). It is also important to note that the junction is not just a result of a random organelle collision but have active and specific formation, stabilisation and disassembly mechanisms. The nature of these mechanisms and their role in physiology/pathophysiology are the main focus of an emerging research field. In this review, we will briefly describe junctional complexes formed by cellular organelles and then focus on the junctional complexes that are formed by mitochondria with other organelles and the role of these complexes in regulating Ca2+ signalling.
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Paupe V, Prudent J. New insights into the role of mitochondrial calcium homeostasis in cell migration. Biochem Biophys Res Commun 2018; 500:75-86. [PMID: 28495532 PMCID: PMC5930976 DOI: 10.1016/j.bbrc.2017.05.039] [Citation(s) in RCA: 83] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Accepted: 05/07/2017] [Indexed: 01/23/2023]
Abstract
Mitochondria are dynamic organelles involved in numerous physiological functions. Beyond their function in ATP production, mitochondria regulate cell death, reactive oxygen species (ROS) generation, immunity and metabolism. Mitochondria also play a key role in the buffering of cytosolic calcium, and calcium transported into the matrix regulates mitochondrial metabolism. Recently, the identification of the mitochondrial calcium uniporter (MCU) and associated regulators has allowed the characterization of new physiological roles for calcium in both mitochondrial and cellular homeostasis. Indeed, recent work has highlighted the importance of mitochondrial calcium homeostasis in regulating cell migration. Cell migration is a property common to all metazoans and is critical to embryogenesis, cancer progression, wound-healing and immune surveillance. Previous work has established that cytoplasmic calcium is a key regulator of cell migration, as oscillations in cytosolic calcium activate cytoskeletal remodelling, actin contraction and focal adhesion (FA) turnover necessary for cell movement. Recent work using animal models and in cellulo experiments to genetically modulate MCU and partners have shed new light on the role of mitochondrial calcium dynamics in cytoskeletal remodelling through the modulation of ATP and ROS production, as well as intracellular calcium signalling. This review focuses on MCU and its regulators in cell migration during physiological and pathophysiological processes including development and cancer. We also present hypotheses to explain the molecular mechanisms by which MCU may regulate mitochondrial dynamics and motility to drive cell migration.
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Affiliation(s)
- Vincent Paupe
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Wellcome Trust/MRC Building, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, United Kingdom
| | - Julien Prudent
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Wellcome Trust/MRC Building, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, United Kingdom.
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Abstract
Calcium (Ca2+) signaling plays a critical role in regulating plethora of cellular functions including cell survival, proliferation and migration. The perturbations in cellular Ca2+ homeostasis can lead to cell death either by activating autophagic pathways or through induction of apoptosis. Endoplasmic reticulum (ER) is the major storehouse of Ca2+ within cells and a number of physiological agonists mediate ER Ca2+ release by activating IP3 receptors (IP3R). This decrease in ER Ca2+ levels is sensed by STIM, which physically interacts and activates plasma membrane Ca2+ selective Orai channels. Emerging literature implicates a key role for STIM1, STIM2, Orai1 and Orai3 in regulating both cell survival and death pathways. In this review, we will retrospect the work highlighting the role of STIM and Orai homologs in regulating cell death signaling. We will further discuss the rationales that could explain the dual role of STIM and Orai proteins in regulating cell fate decisions.
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Spät A, Szanda G. The Role of Mitochondria in the Activation/Maintenance of SOCE: Store-Operated Ca 2+ Entry and Mitochondria. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 993:257-275. [PMID: 28900919 DOI: 10.1007/978-3-319-57732-6_14] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Mitochondria extensively modify virtually all cellular Ca2+ transport processes, and store-operated Ca2+ entry (SOCE) is no exception to this rule. The interaction between SOCE and mitochondria is complex and reciprocal, substantially altering and, ultimately, fine-tuning both capacitative Ca2+ influx and mitochondrial function. Mitochondria, owing to their considerable Ca2+ accumulation ability, extensively buffer the cytosolic Ca2+ in their vicinity. In turn, the accumulated ion is released back into the neighboring cytosol during net Ca2+ efflux. Since store depletion itself and the successive SOCE are both Ca2+-regulated phenomena, mitochondrial Ca2+ handling may have wide-ranging effects on capacitative Ca2+ influx at any given time. In addition, mitochondria may also produce or consume soluble factors known to affect store-operated channels. On the other hand, Ca2+ entering the cell during SOCE is sensed by mitochondria, and the ensuing mitochondrial Ca2+ uptake boosts mitochondrial energy metabolism and, if Ca2+ overload occurs, may even lead to apoptosis or cell death. In several cell types, mitochondria seem to be sterically excluded from the confined space that forms between the plasma membrane (PM) and endoplasmic reticulum (ER) during SOCE. This implies that high-Ca2+ microdomains comparable to those observed between the ER and mitochondria do not form here. In the following chapter, the above aspects of the many-sided SOCE-mitochondrion interplay will be discussed in greater detail.
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Affiliation(s)
- András Spät
- Department of Physiology, Semmelweis University Medical School, POB 2, 1428, Budapest, Hungary.
- Laboratory of Molecular Physiology, Hungarian Academy of Sciences, Budapest, Hungary.
| | - Gergö Szanda
- Department of Physiology, Semmelweis University Medical School, POB 2, 1428, Budapest, Hungary
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Fonteriz R, Matesanz-Isabel J, Arias-Del-Val J, Alvarez-Illera P, Montero M, Alvarez J. Modulation of Calcium Entry by Mitochondria. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 898:405-21. [PMID: 27161238 DOI: 10.1007/978-3-319-26974-0_17] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The role of mitochondria in intracellular Ca(2+) signaling relies mainly in its capacity to take up Ca(2+) from the cytosol and thus modulate the cytosolic [Ca(2+)]. Because of the low Ca(2+)-affinity of the mitochondrial Ca(2+)-uptake system, this organelle appears specially adapted to take up Ca(2+) from local high-Ca(2+) microdomains and not from the bulk cytosol. Mitochondria would then act as local Ca(2+) buffers in cellular regions where high-Ca(2+) microdomains form, that is, mainly close to the cytosolic mouth of Ca(2+) channels, both in the plasma membrane and in the endoplasmic reticulum (ER). One of the first targets proposed already in the 1990s to be regulated in this way by mitochondria were the store-operated Ca(2+) channels (SOCE). Mitochondria, by taking up Ca(2+) from the region around the cytosolic mouth of the SOCE channels, would prevent its slow Ca(2+)-dependent inactivation, thus keeping them active for longer. Since then, evidence for this mechanism has accumulated mainly in immunitary cells, where mitochondria actually move towards the immune synapse during T cell activation. However, in many other cell types the available data indicate that the close apposition between plasma and ER membranes occurring during SOCE activation precludes mitochondria from getting close to the Ca(2+)-entry sites. Alternative pathways for mitochondrial modulation of SOCE, both Ca(2+)-dependent and Ca(2+)-independent, have also been proposed, but further work will be required to elucidate the actual mechanisms at work. Hopefully, the recent knowledge of the molecular nature of the mitochondrial Ca(2+) uniporter will allow soon more precise studies on this matter.
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Affiliation(s)
- Rosalba Fonteriz
- Departamento de Bioquímica y Biología Molecular y Fisiología, Instituto de Biología y Genética Molecular (IBGM), Facultad de Medicina, Universidad de Valladolid y Consejo Superior de Investigaciones Científicas, Ramon y Cajal 7, 47005, Valladolid, Spain
| | - Jessica Matesanz-Isabel
- Departamento de Bioquímica y Biología Molecular y Fisiología, Instituto de Biología y Genética Molecular (IBGM), Facultad de Medicina, Universidad de Valladolid y Consejo Superior de Investigaciones Científicas, Ramon y Cajal 7, 47005, Valladolid, Spain
| | - Jessica Arias-Del-Val
- Departamento de Bioquímica y Biología Molecular y Fisiología, Instituto de Biología y Genética Molecular (IBGM), Facultad de Medicina, Universidad de Valladolid y Consejo Superior de Investigaciones Científicas, Ramon y Cajal 7, 47005, Valladolid, Spain
| | - Pilar Alvarez-Illera
- Departamento de Bioquímica y Biología Molecular y Fisiología, Instituto de Biología y Genética Molecular (IBGM), Facultad de Medicina, Universidad de Valladolid y Consejo Superior de Investigaciones Científicas, Ramon y Cajal 7, 47005, Valladolid, Spain
| | - Mayte Montero
- Departamento de Bioquímica y Biología Molecular y Fisiología, Instituto de Biología y Genética Molecular (IBGM), Facultad de Medicina, Universidad de Valladolid y Consejo Superior de Investigaciones Científicas, Ramon y Cajal 7, 47005, Valladolid, Spain
| | - Javier Alvarez
- Departamento de Bioquímica y Biología Molecular y Fisiología, Instituto de Biología y Genética Molecular (IBGM), Facultad de Medicina, Universidad de Valladolid y Consejo Superior de Investigaciones Científicas, Ramon y Cajal 7, 47005, Valladolid, Spain.
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Abstract
Store-operated calcium channels (SOCs) are a major pathway for calcium signaling in virtually all metozoan cells and serve a wide variety of functions ranging from gene expression, motility, and secretion to tissue and organ development and the immune response. SOCs are activated by the depletion of Ca(2+) from the endoplasmic reticulum (ER), triggered physiologically through stimulation of a diverse set of surface receptors. Over 15 years after the first characterization of SOCs through electrophysiology, the identification of the STIM proteins as ER Ca(2+) sensors and the Orai proteins as store-operated channels has enabled rapid progress in understanding the unique mechanism of store-operate calcium entry (SOCE). Depletion of Ca(2+) from the ER causes STIM to accumulate at ER-plasma membrane (PM) junctions where it traps and activates Orai channels diffusing in the closely apposed PM. Mutagenesis studies combined with recent structural insights about STIM and Orai proteins are now beginning to reveal the molecular underpinnings of these choreographic events. This review describes the major experimental advances underlying our current understanding of how ER Ca(2+) depletion is coupled to the activation of SOCs. Particular emphasis is placed on the molecular mechanisms of STIM and Orai activation, Orai channel properties, modulation of STIM and Orai function, pharmacological inhibitors of SOCE, and the functions of STIM and Orai in physiology and disease.
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Affiliation(s)
- Murali Prakriya
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois; and Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, California
| | - Richard S Lewis
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois; and Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, California
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Abstract
The regulatory protein STIM1 controls gating of the Ca(2+) channel ORAI1 by a direct protein-protein interaction. Because STIM1 is anchored in the ER membrane and ORAI1 is in the plasma membrane, the STIM-ORAI pathway can support Ca(2+) influx only where the two membranes come into close apposition, effectively demarcating a microdomain for Ca(2+) signalling. This review begins with a brief summary of the STIM-ORAI pathway of store-operated Ca(2+) influx, then turns to the special geometry of the STIM-ORAI microdomain and the expected characteristics of the microdomain Ca(2+) signal. A final section of the review seeks to place the STIM-ORAI microdomain into a broader context of cellular Ca(2+) signalling.
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Affiliation(s)
- Patrick G Hogan
- La Jolla Institute for Allergy & Immunology, La Jolla, CA 92037, USA.
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García-Sancho J. The coupling of plasma membrane calcium entry to calcium uptake by endoplasmic reticulum and mitochondria. J Physiol 2013; 592:261-8. [PMID: 23798493 DOI: 10.1113/jphysiol.2013.255661] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Cross-talk between organelles and plasma membrane Ca(2+) channels is essential for modulation of the cytosolic Ca(2+) ([Ca(2+)]C) signals, but such modulation may differ among cells. In chromaffin cells Ca(2+) entry through voltage-operated channels induces calcium release from the endoplasmic reticulum (ER) that amplifies the signal. [Ca(2+)]C microdomains as high as 20-50 μm are sensed by subplasmalemmal mitochondria, which accumulate large amounts of Ca(2+) through the mitochondrial Ca(2+) uniporter (MCU). Mitochondria confine the high-Ca(2+) microdomains (HCMDs) to beneath the plasma membrane, where exocytosis of secretory vesicles happens. Cell core [Ca(2+)]C is much smaller (1-2 μm). By acting as a Ca(2+) sink, mitochondria stabilise the HCMD in space and time. In non-excitable HEK293 cells, activation of store-operated Ca(2+) entry, triggered by ER Ca(2+) emptying, also generated subplasmalemmal HCMDs, but, in this case, most of the Ca(2+) was taken up by the ER rather than by mitochondria. The smaller size of the [Ca(2+)]C peak in this case (about 2 μm) may contribute to this outcome, as the sarco-endoplasmic reticulum Ca(2+) ATPase has much higher Ca(2+) affinity than MCU. It is also possible that the relative positioning of organelles, channels and effectors, as well as cytoskeleton and accessory proteins plays an important role.
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Stefan CJ, Manford AG, Emr SD. ER-PM connections: sites of information transfer and inter-organelle communication. Curr Opin Cell Biol 2013; 25:434-42. [PMID: 23522446 DOI: 10.1016/j.ceb.2013.02.020] [Citation(s) in RCA: 159] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2013] [Revised: 02/25/2013] [Accepted: 02/28/2013] [Indexed: 11/18/2022]
Abstract
Eukaryotic cells are divided into distinct membrane-bound organelles with unique identities and specialized metabolic functions. Communication between organelles must take place to regulate the size, shape, and composition of individual organelles, as well as to coordinate transport between organelles. The endoplasmic reticulum (ER) forms an expansive membrane network that contacts and participates in crosstalk with several other organelles in the cell, most notably the plasma membrane (PM). ER-PM junctions have well-established functions in the movement of small molecules, such as lipids and ions, between the ER and PM. Recent discoveries have revealed additional exciting roles for ER-PM junctions in the regulation of cell signaling, ER shape and architecture, and PM domain organization.
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Affiliation(s)
- Christopher J Stefan
- Weill Institute for Cell & Molecular Biology, Department of Molecular Biology & Genetics, Cornell University, Ithaca, NY 14853, United States.
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14
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Abstract
Mitochondria may function as multiple separate organelles or as a single electrically coupled continuum to modulate changes in [Ca2+]c (cytoplasmic Ca2+ concentration) in various cell types. Mitochondria may also be tethered to the internal Ca2+ store or plasma membrane in particular parts of cells to facilitate the organelles modulation of local and global [Ca2+]c increases. Differences in the organization and positioning contributes significantly to the at times apparently contradictory reports on the way mitochondria modulate [Ca2+]c signals. In the present paper, we review the organization of mitochondria and the organelles role in Ca2+ signalling.
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15
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Alonso MT, Manjarrés IM, García-Sancho J. Privileged coupling between Ca(2+) entry through plasma membrane store-operated Ca(2+) channels and the endoplasmic reticulum Ca(2+) pump. Mol Cell Endocrinol 2012; 353:37-44. [PMID: 21878366 DOI: 10.1016/j.mce.2011.08.021] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2011] [Revised: 08/10/2011] [Accepted: 08/15/2011] [Indexed: 12/17/2022]
Abstract
The sarco/endoplasmic reticulum Ca(2+)-ATPase (SERCA) is the third element of capacitative calcium entry. It colocalizes with STIM1 and Orai1 at puncta, where couples plasma membrane store-operated Ca(2+) channels (SOC) to Ca(2+) pumping into the ER. The efficiency of this calcium entry-calcium refilling (CECR) coupling is comparable to the classic excitation-response transduction mechanisms. This allows efficient filling of the endoplasmic reticulum (ER) with the Ca(2+) entering through SOC channels with little progression of the Ca(2+) wave towards the cell core. CECR coupling is very sensitive to changes in stoichiometry among STIM, Orai and SERCA, with excess Orai antagonizing ER refilling. ER takes up most of the calcium load that enters through SOC, whereas mitochondria take up a very small fraction. This difference is due to the spatial positioning with regard to SOC, the amplitude of the high Ca(2+) microdomains, and the differences in the Ca(2+) affinity of the uptake mechanisms.
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Affiliation(s)
- María Teresa Alonso
- Instituto de Biología y Genética Molecular, Universidad de Valladolid y Consejo Superior de Investigaciones Científicas, c/ Sanz y Forés s/n, 47003 Valladolid, Spain
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16
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Csordás G, Várnai P, Golenár T, Sheu SS, Hajnóczky G. Calcium transport across the inner mitochondrial membrane: molecular mechanisms and pharmacology. Mol Cell Endocrinol 2012; 353:109-13. [PMID: 22123069 PMCID: PMC3295916 DOI: 10.1016/j.mce.2011.11.011] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/19/2011] [Revised: 11/10/2011] [Accepted: 11/10/2011] [Indexed: 01/21/2023]
Abstract
Growing evidence supports that mitochondrial calcium uptake is important for cell metabolism, signaling and survival. However, both the molecular nature of the mitochondrial Ca(2+) transport sites and the calcium signals they respond to remained elusive. Recent RNA interference studies have identified new candidate proteins for Ca(2+) transport across the inner mitochondrial membrane, including LETM1, MCU, MICU1 and NCLX. The sensitivity of these factors to several drugs has been tested and in parallel, some new inhibitors of mitochondrial Ca(2+) uptake have been described. This paper provides an update on the pharmacological aspects of the molecular mechanisms of the inner mitochondrial membrane Ca(2+) transport.
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Affiliation(s)
- György Csordás
- Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107
| | - Peter Várnai
- Department of Physiology, Semmelweis University Budapest, Hungary
| | - Tünde Golenár
- Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107
| | - Shey-Shing Sheu
- Center for Translational Medicine, Thomas Jefferson University, Philadelphia, PA 19107
| | - György Hajnóczky
- Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107
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17
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Spät A, Szanda G. Special features of mitochondrial Ca²⁺ signalling in adrenal glomerulosa cells. Pflugers Arch 2012; 464:43-50. [PMID: 22395411 DOI: 10.1007/s00424-012-1086-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2012] [Revised: 02/10/2012] [Accepted: 02/14/2012] [Indexed: 11/30/2022]
Abstract
Aldosterone, secreted by adrenal glomerulosa cells, allows the adaptation of the vertebrate organism to a wide range of physiological and pathological stimuli including acute haemodynamic challenges and long-term changes in dietary sodium and potassium intake. Most of the extracellular signals are mediated by cytosolic Ca²⁺ signal deriving from Ca²⁺ release, store-operated and/or voltage-gated Ca²⁺ influx. Mitochondria in glomerulosa cells play a fundamental role in generating and modulating the final biological response. These organelles not only house several enzymes of aldosterone biosynthesis but also-in a Ca²⁺-dependent manner-provide NADPH for the function of these enzymes. Moreover, mitochondria, constituting a high portion of cytoplasmic volume and displaying a uniquely low-threshold Ca²⁺ sequestering ability, shape and thus modulate the decoding of the complex cytosolic Ca²⁺ response. The unusual features of mitochondrial Ca²⁺ signalling that permit such an integrative function in adrenal glomerulosa cells are hereby described.
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Affiliation(s)
- András Spät
- Department of Physiology, Semmelweis University, Budapest, Hungary.
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18
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Kann O, Taubenberger N, Huchzermeyer C, Papageorgiou IE, Benninger F, Heinemann U, Kovács R. Muscarinic receptor activation determines the effects of store-operated Ca2+-entry on excitability and energy metabolism in pyramidal neurons. Cell Calcium 2012; 51:40-50. [DOI: 10.1016/j.ceca.2011.10.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2011] [Revised: 10/14/2011] [Accepted: 10/19/2011] [Indexed: 10/15/2022]
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Abstract
Eukaryotic organelles can interact with each other through stable junctions where the two membranes are kept in close apposition. The junction that connects the endoplasmic reticulum to the plasma membrane (ER-PM junction) is unique in providing a direct communication link between the ER and the PM. In a recently discovered signaling process, STIM (stromal-interacting molecule) proteins sense a drop in ER Ca(2+) levels and directly activate Orai PM Ca(2+) channels across the junction space. In an inverse process, a voltage-gated PM Ca(2+) channel can directly open ER ryanodine-receptor Ca(2+) channels in striated-muscle cells. Although ER-PM junctions were first described 50 years ago, their broad importance in Ca(2+) signaling, as well as in the regulation of cholesterol and phosphatidylinositol lipid transfer, has only recently been realized. Here, we discuss research from different fields to provide a broad perspective on the structures and unique roles of ER-PM junctions in controlling signaling and metabolic processes.
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Affiliation(s)
- Silvia Carrasco
- Department of Chemical and Systems Biology, School of Medicine, Stanford University, Stanford, California 94305, USA.
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20
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Konieczny V, Keebler MV, Taylor CW. Spatial organization of intracellular Ca2+ signals. Semin Cell Dev Biol 2011; 23:172-80. [PMID: 21925615 DOI: 10.1016/j.semcdb.2011.09.006] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2011] [Accepted: 09/08/2011] [Indexed: 01/08/2023]
Abstract
The ability of Ca(2+), the simplest of all intracellular messengers, selectively to regulate so many cellular behaviours is due largely to the complex spatiotemporal organization of intracellular Ca(2+) signals. Most signalling pathways, including those that culminate in Ca(2+) signals, comprise sequences of protein-protein interactions linked by diffusible messengers. Using specific examples to illustrate key principles, we consider the roles of both components in defining the spatial organization of Ca(2+) signals. We discuss evidence that regulation of most Ca(2+) channels by Ca(2+) contributes to controlling the duration of Ca(2+) signals, to signal integration and, via Ca(2+)-induced Ca(2+) release, to defining the spatial spread of Ca(2+) signals. We distinguish two types of protein-protein interaction: scaffolds that allow rapid local transfer of diffusible messengers between signalling proteins, and interactions that directly transfer information between signalling proteins. Store-operated Ca(2+) entry provides a ubiquitous example of the latter, and it serves also to illustrate how Ca(2+) signals can be organized at different levels of spatial organization - from interactions between proteins to interactions between organelles.
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Affiliation(s)
- Vera Konieczny
- Department of Pharmacology, Tennis Court Road, Cambridge CB2 1PD, UK
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21
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Calcium microdomains at the immunological synapse: how ORAI channels, mitochondria and calcium pumps generate local calcium signals for efficient T-cell activation. EMBO J 2011; 30:3895-912. [PMID: 21847095 DOI: 10.1038/emboj.2011.289] [Citation(s) in RCA: 156] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2010] [Accepted: 07/19/2011] [Indexed: 12/24/2022] Open
Abstract
Cell polarization enables restriction of signalling into microdomains. Polarization of lymphocytes following formation of a mature immunological synapse (IS) is essential for calcium-dependent T-cell activation. Here, we analyse calcium microdomains at the IS with total internal reflection fluorescence microscopy. We find that the subplasmalemmal calcium signal following IS formation is sufficiently low to prevent calcium-dependent inactivation of ORAI channels. This is achieved by localizing mitochondria close to ORAI channels. Furthermore, we find that plasma membrane calcium ATPases (PMCAs) are re-distributed into areas beneath mitochondria, which prevented PMCA up-modulation and decreased calcium export locally. This nano-scale distribution-only induced following IS formation-maximizes the efficiency of calcium influx through ORAI channels while it decreases calcium clearance by PMCA, resulting in a more sustained NFAT activity and subsequent activation of T cells.
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Calcium entry-calcium refilling (CECR) coupling between store-operated Ca(2+) entry and sarco/endoplasmic reticulum Ca(2+)-ATPase. Cell Calcium 2011; 49:153-61. [PMID: 21353305 DOI: 10.1016/j.ceca.2011.01.007] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2010] [Revised: 01/15/2011] [Accepted: 01/20/2011] [Indexed: 01/07/2023]
Abstract
Cross-talk between subcellular organelles is essential for cellular Ca(2+) homeostasis. We have studied the effects of knocking down STIM1, the Ca(2+) sensor of the endoplasmic reticulum (ER), on several homeostatic Ca(2+)-handling mechanisms, including plasma membrane Ca(2+) entry and transport by ER, mitochondria and nucleus. We have used targeted aequorins to selectively measure calcium fluxes in different organelles. Actions of STIM1 were extremely selective, restricted to store operated Ca(2+) channels (SOC) and Ca(2+) uptake by the ER. No interactions with uptake or release of Ca(2+) by mitochondria or nucleus were detected. Ca(2+) exit from the ER, including passive leak, release via inositol 1,4,5-trisphosphate and ryanodine receptors, was unaffected. STIM1 knock-down inhibited ER Ca(2+) uptake in intact but not in permeabilized cells, suggesting a privileged calcium entry-calcium refilling (CECR) coupling between plasma membrane SOC and ER calcium pump in the intact cell. As a result a large part of the entering Ca(2+) is taken up into the ER without reaching the bulk cytosol. The tightness of CECR, as measured by the slope of the stimulus-signal strength function, was comparable to classic excitation-response coupling mechanisms, such as excitation-contraction, excitation-secretion or excitation-transcription coupling.
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23
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Fluorescent Genetically Encoded Calcium Indicators and Their In Vivo Application. FLUORESCENT PROTEINS II 2011. [DOI: 10.1007/4243_2011_29] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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Naghdi S, Waldeck-Weiermair M, Fertschai I, Poteser M, Graier WF, Malli R. Mitochondrial Ca2+ uptake and not mitochondrial motility is required for STIM1-Orai1-dependent store-operated Ca2+ entry. J Cell Sci 2010; 123:2553-64. [DOI: 10.1242/jcs.070151] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Store-operated Ca2+ entry (SOCE) is established by formation of subplasmalemmal clusters of the endoplasmic reticulum (ER) protein, stromal interacting molecule 1 (STIM1) upon ER Ca2+ depletion. Thereby, STIM1 couples to plasma membrane channels such as Orai1. Thus, a close proximity of ER domains to the plasma membrane is a prerequisite for SOCE activation, challenging the concept of local Ca2+ buffering by mitochondria as being essential for SOCE. This study assesses the impact of mitochondrial Ca2+ handling and motility on STIM1–Orai1-dependent SOCE. High-resolution microscopy showed only 10% of subplasmalemmal STIM1 clusters to be colocalized with mitochondria. Impairments of mitochondrial Ca2+ handling by inhibition of mitochondrial Na+-Ca2+ exchanger (NCXmito) or depolarization only partially suppressed Ca2+ entry in cells overexpressing STIM1-Orai1. However, SOCE was completely abolished when both NCXmito was inhibited and the inner mitochondrial membrane was depolarized, in STIM1- and Orai1-overexpressing cells. Immobilization of mitochondria by expression of mAKAP-RFP-CAAX, a construct that physically links mitochondria to the plasma membrane, affected the Ca2+ handling of the organelles but not the activity of SOCE. Our observations indicate that mitochondrial Ca2+ uptake, including reversal of NCXmito, is fundamental for STIM1–Orai1-dependent SOCE, whereas the proximity of mitochondria to STIM1-Orai1 SOCE units and their motility is not required.
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Affiliation(s)
- Shamim Naghdi
- Institute of Molecular Biology and Biochemistry, Center of Molecular Medicine, Medical University of Graz, 8010 Graz, Austria
| | - Markus Waldeck-Weiermair
- Institute of Molecular Biology and Biochemistry, Center of Molecular Medicine, Medical University of Graz, 8010 Graz, Austria
| | - Ismene Fertschai
- Institute of Molecular Biology and Biochemistry, Center of Molecular Medicine, Medical University of Graz, 8010 Graz, Austria
| | - Michael Poteser
- Institute of Molecular Biology and Biochemistry, Center of Molecular Medicine, Medical University of Graz, 8010 Graz, Austria
| | - Wolfgang F. Graier
- Institute of Molecular Biology and Biochemistry, Center of Molecular Medicine, Medical University of Graz, 8010 Graz, Austria
| | - Roland Malli
- Institute of Molecular Biology and Biochemistry, Center of Molecular Medicine, Medical University of Graz, 8010 Graz, Austria
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25
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Csordás G, Várnai P, Golenár T, Roy S, Purkins G, Schneider TG, Balla T, Hajnóczky G. Imaging interorganelle contacts and local calcium dynamics at the ER-mitochondrial interface. Mol Cell 2010; 39:121-32. [PMID: 20603080 DOI: 10.1016/j.molcel.2010.06.029] [Citation(s) in RCA: 551] [Impact Index Per Article: 39.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2009] [Revised: 04/09/2010] [Accepted: 06/14/2010] [Indexed: 12/11/2022]
Abstract
The ER-mitochondrial junction provides a local calcium signaling domain that is critical for both matching energy production with demand and the control of apoptosis. Here, we visualize ER-mitochondrial contact sites and monitor the localized [Ca(2+)] changes ([Ca(2+)](ER-mt)) using drug-inducible fluorescent interorganelle linkers. We show that all mitochondria have contacts with the ER, but plasma membrane (PM)-mitochondrial contacts are less frequent because of interleaving ER stacks in both RBL-2H3 and H9c2 cells. Single mitochondria display discrete patches of ER contacts and show heterogeneity in the ER-mitochondrial Ca(2+) transfer. Pericam-tagged linkers revealed IP(3)-induced [Ca(2+)](ER-mt) signals that exceeded 9 microM and endured buffering bulk cytoplasmic [Ca(2+)] increases. Altering linker length to modify the space available for the Ca(2+) transfer machinery had a biphasic effect on [Ca(2+)](ER-mt) signals. These studies provide direct evidence for the existence of high-Ca(2+) microdomains between the ER and mitochondria and suggest an optimal gap width for efficient Ca(2+) transfer.
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Affiliation(s)
- György Csordás
- Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA
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Giacomello M, Drago I, Bortolozzi M, Scorzeto M, Gianelle A, Pizzo P, Pozzan T. Ca2+ hot spots on the mitochondrial surface are generated by Ca2+ mobilization from stores, but not by activation of store-operated Ca2+ channels. Mol Cell 2010; 38:280-90. [PMID: 20417605 DOI: 10.1016/j.molcel.2010.04.003] [Citation(s) in RCA: 313] [Impact Index Per Article: 22.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2009] [Revised: 12/21/2009] [Accepted: 02/03/2010] [Indexed: 12/19/2022]
Abstract
Although it is widely accepted that mitochondria in living cells can efficiently uptake Ca(2+) during stimulation because of their vicinity to microdomains of high [Ca(2+)], the direct proof of Ca(2+) hot spots' existence is still lacking. Thanks to a GFP-based Ca(2+) probe localized on the cytosolic surface of the outer mitochondrial membrane, we demonstrate that, upon Ca(2+) mobilization, the [Ca(2+)] in small regions of the mitochondrial surface reaches levels 5- to 10-fold higher than in the bulk cytosol. We also show that the [Ca(2+)] to which mitochondria are exposed during capacitative Ca(2+) influx is similar between near plasma membrane mitochondria and organelles deeply located in the cytoplasm, whereas it is 2- to 3-fold higher in subplasma membrane mitochondria upon activation of voltage-gated Ca(2+) channels. These results demonstrate that mitochondria are exposed to Ca(2+) hot spots close to the ER but are excluded from the regions where capacitative Ca(2+) influx occurs.
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Affiliation(s)
- Marta Giacomello
- Department of Biomedical Sciences, University of Padova, Padova, Italy
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