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Valiente-Gabioud AA, Garteizgogeascoa Suñer I, Idziak A, Fabritius A, Basquin J, Angibaud J, Nägerl UV, Singh SP, Griesbeck O. Fluorescent sensors for imaging of interstitial calcium. Nat Commun 2023; 14:6220. [PMID: 37798285 PMCID: PMC10556026 DOI: 10.1038/s41467-023-41928-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Accepted: 09/22/2023] [Indexed: 10/07/2023] Open
Abstract
Calcium in interstitial fluids is central to systemic physiology and a crucial ion pool for entry into cells through numerous plasma membrane channels. Its study has been limited by the scarcity of methods that allow monitoring in tight inter-cell spaces of living tissues. Here we present high performance ultra-low affinity genetically encoded calcium biosensors named GreenT-ECs. GreenT-ECs combine large fluorescence changes upon calcium binding and binding affinities (Kds) ranging from 0.8 mM to 2.9 mM, making them tuned to calcium concentrations in extracellular organismal fluids. We validated GreenT-ECs in rodent hippocampal neurons and transgenic zebrafish in vivo, where the sensors enabled monitoring homeostatic regulation of tissue interstitial calcium. GreenT-ECs may become useful for recording very large calcium transients and for imaging calcium homeostasis in inter-cell structures in live tissues and organisms.
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Affiliation(s)
- Ariel A Valiente-Gabioud
- Max Planck Institute for Biological Intelligence, Tools for Bio-Imaging, Am Klopferspitz 18, 82152, Martinsried, Germany
| | - Inés Garteizgogeascoa Suñer
- Institute de Recherche Interdisciplinaire en Biologie Humaine et Moléculaire (IRIBHM), 808 Route de Lennik, Université Libre de Bruxelles (ULB), 1070, Brussels, Belgium
| | - Agata Idziak
- Institut Interdisciplinaire de Neurosciences, Synaptic Plasticity and Super-Resolution Microscopy, CNRS - Université de Bordeaux - 146 rue Léo-Saignat, Bordeaux, France
| | - Arne Fabritius
- Max Planck Institute for Biological Intelligence, Tools for Bio-Imaging, Am Klopferspitz 18, 82152, Martinsried, Germany
| | - Jérome Basquin
- Structural Cell Biology, Max-Planck-Institute for Biochemistry, Am Klopferspitz 18, Martinsried, 82152, Germany
| | - Julie Angibaud
- Institut Interdisciplinaire de Neurosciences, Synaptic Plasticity and Super-Resolution Microscopy, CNRS - Université de Bordeaux - 146 rue Léo-Saignat, Bordeaux, France
| | - U Valentin Nägerl
- Institut Interdisciplinaire de Neurosciences, Synaptic Plasticity and Super-Resolution Microscopy, CNRS - Université de Bordeaux - 146 rue Léo-Saignat, Bordeaux, France
| | - Sumeet Pal Singh
- Institute de Recherche Interdisciplinaire en Biologie Humaine et Moléculaire (IRIBHM), 808 Route de Lennik, Université Libre de Bruxelles (ULB), 1070, Brussels, Belgium
| | - Oliver Griesbeck
- Max Planck Institute for Biological Intelligence, Tools for Bio-Imaging, Am Klopferspitz 18, 82152, Martinsried, Germany.
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Valiente-Gabioud AA, Fabritius A, Griesbeck O. Probing the interstitial calcium compartment. J Physiol 2023; 601:4217-4226. [PMID: 36073135 DOI: 10.1113/jp279510] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Accepted: 08/30/2022] [Indexed: 11/08/2022] Open
Abstract
Calcium in interstitial fluids is a crucial ion pool for entry into cells through a plethora of calcium-permeable channels. It is also sensed actively by dedicated receptors. While the mechanisms of global calcium homeostasis and regulation in body fluids appear well understood, more efforts and new technology are needed to elucidate local calcium handling in the small and relatively isolated interstitial spaces between cells. Here we review current methodology for monitoring interstitial calcium and highlight the potential of new approaches for its study. In particular, new generations of high-performance low-affinity genetically encoded calcium indicators could allow imaging of calcium in relatively inaccessible intercellular structures in live tissues and organisms.
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Affiliation(s)
- Ariel A Valiente-Gabioud
- Tools for Bio-Imaging, Max-Planck-Institute for Biological Intelligence (i.F.), Martinsried, Germany
| | - Arne Fabritius
- Tools for Bio-Imaging, Max-Planck-Institute for Biological Intelligence (i.F.), Martinsried, Germany
| | - Oliver Griesbeck
- Tools for Bio-Imaging, Max-Planck-Institute for Biological Intelligence (i.F.), Martinsried, Germany
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3
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Gerasimenko JV, Gerasimenko OV. The role of Ca 2+ signalling in the pathology of exocrine pancreas. Cell Calcium 2023; 112:102740. [PMID: 37058923 PMCID: PMC10840512 DOI: 10.1016/j.ceca.2023.102740] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 04/04/2023] [Accepted: 04/06/2023] [Indexed: 04/16/2023]
Abstract
Exocrine pancreas has been the field of many successful studies in pancreatic physiology and pathology. However, related disease - acute pancreatitis (AP) is still takes it toll with more than 100,000 related deaths worldwide per year. In spite of significant scientific progress and several human trials currently running for AP, there is still no specific treatment in the clinic. Studies of the mechanism of initiation of AP have identified two crucial conditions: sustained elevations of cytoplasmic calcium concentration (Ca2+ plateau) and significantly reduced intracellular energy (ATP depletion). These hallmarks are interdependent, i.e., Ca2+ plateau increase energy demand for its clearance while energy production is greatly affected by the pathology. Result of long standing Ca2+ plateau is destabilisation of the secretory granules and premature activation of the digestive enzymes leading to necrotic cell death. Main attempts so far to break the vicious circle of cell death have been concentrated on reduction of Ca2+ overload or reduction of ATP depletion. This review will summarise these approaches, including recent developments of potential therapies for AP.
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Affiliation(s)
- Julia V Gerasimenko
- Cardiff School of Biosciences, Cardiff University, Museum Avenue, Cardiff, Wales, CF10 3AX, United Kingdom.
| | - Oleg V Gerasimenko
- Cardiff School of Biosciences, Cardiff University, Museum Avenue, Cardiff, Wales, CF10 3AX, United Kingdom
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4
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Petersen OH. Watching Living Cells in Action in the Exocrine Pancreas: The Palade Prize Lecture. FUNCTION 2022; 4:zqac061. [PMID: 36606242 PMCID: PMC9809903 DOI: 10.1093/function/zqac061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Revised: 12/04/2022] [Accepted: 12/05/2022] [Indexed: 12/13/2022] Open
Abstract
George Palade's pioneering electron microscopical studies of the pancreatic acinar cell revealed the intracellular secretory pathway from the rough endoplasmic reticulum at the base of the cell to the zymogen granules in the apical region. Palade also described for the first time the final stage of exocytotic enzyme secretion into the acinar lumen. The contemporary studies of the mechanism by which secretion is acutely controlled, and how the pancreas is destroyed in the disease acute pancreatitis, rely on monitoring molecular events in the various identified pancreatic cell types in the living pancreas. These studies have been carried out with the help of high-resolution fluorescence recordings, often in conjunction with patch clamp current measurements. In such studies we have gained much detailed information about the regulatory events in the exocrine pancreas in health as well as disease, and new therapeutic opportunities have been revealed.
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Affiliation(s)
- Ole H Petersen
- School of Biosciences, Sir Martin Evans Building, Cardiff University, Wales, CF10 3AX, UK
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5
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Petersen OH, Gerasimenko JV, Gerasimenko OV, Gryshchenko O, Peng S. The roles of calcium and ATP in the physiology and pathology of the exocrine pancreas. Physiol Rev 2021; 101:1691-1744. [PMID: 33949875 DOI: 10.1152/physrev.00003.2021] [Citation(s) in RCA: 61] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
This review deals with the roles of calcium ions and ATP in the control of the normal functions of the different cell types in the exocrine pancreas as well as the roles of these molecules in the pathophysiology of acute pancreatitis. Repetitive rises in the local cytosolic calcium ion concentration in the apical part of the acinar cells not only activate exocytosis but also, via an increase in the intramitochondrial calcium ion concentration, stimulate the ATP formation that is needed to fuel the energy-requiring secretion process. However, intracellular calcium overload, resulting in a global sustained elevation of the cytosolic calcium ion concentration, has the opposite effect of decreasing mitochondrial ATP production, and this initiates processes that lead to necrosis. In the last few years it has become possible to image calcium signaling events simultaneously in acinar, stellate, and immune cells in intact lobules of the exocrine pancreas. This has disclosed processes by which these cells interact with each other, particularly in relation to the initiation and development of acute pancreatitis. By unraveling the molecular mechanisms underlying this disease, several promising therapeutic intervention sites have been identified. This provides hope that we may soon be able to effectively treat this often fatal disease.
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Affiliation(s)
- Ole H Petersen
- School of Biosciences, Cardiff University, Cardiff, United Kingdom
| | | | | | | | - Shuang Peng
- Department of Pathophysiology, Key Laboratory of State Administration of Traditional Chinese Medicine of the People's Republic of China, School of Medicine, Jinan University, Guangzhou, Guangdong, People's Republic of China
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6
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Guse AH, Gil Montoya DC, Diercks BP. Mechanisms and functions of calcium microdomains produced by ORAI channels, d-myo-inositol 1,4,5-trisphosphate receptors, or ryanodine receptors. Pharmacol Ther 2021; 223:107804. [PMID: 33465399 DOI: 10.1016/j.pharmthera.2021.107804] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Accepted: 01/04/2021] [Indexed: 12/24/2022]
Abstract
With the discovery of local Ca2+ signals in the 1990s the concept of 'elementary Ca2+ signals' and 'fundamental Ca2+ signals' was developed. While 'elementary Ca2+signals' relate to optical signals gained by activity of small clusters of Ca2+channels, 'fundamental signals' describe such optical signals that arise from opening of single Ca2+channels. In this review, we discuss (i) concepts of local Ca2+ signals and Ca2+ microdomains, (ii) molecular mechanisms underlying Ca2+ microdomains, (iii) functions of Ca2+ microdomains, and (iv) mathematical modelling of Ca2+ microdomains. We focus on Ca2+ microdomains produced by ORAI channels, D-myo-inositol 1,4,5-trisphosphate receptors, or ryanodine receptors. In summary, research on local Ca2+ signals in different cell models aims to better understand how cells use the Ca2+ toolkit to produce Ca2+ microdomains as relevant signals for specific cellular responses, but also how local Ca2+ signals as building blocks merge into global Ca2+ signaling.
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Affiliation(s)
- Andreas H Guse
- The Calcium Signalling Group, Dept of Biochemistry and Molecular Cell Biology, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, D-20246 Hamburg, Germany.
| | - Diana C Gil Montoya
- The Calcium Signalling Group, Dept of Biochemistry and Molecular Cell Biology, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, D-20246 Hamburg, Germany
| | - Björn-Philipp Diercks
- The Calcium Signalling Group, Dept of Biochemistry and Molecular Cell Biology, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, D-20246 Hamburg, Germany
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7
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8
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9
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Gerbino A, Colella M. The Different Facets of Extracellular Calcium Sensors: Old and New Concepts in Calcium-Sensing Receptor Signalling and Pharmacology. Int J Mol Sci 2018; 19:E999. [PMID: 29584660 PMCID: PMC5979557 DOI: 10.3390/ijms19040999] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Revised: 03/23/2018] [Accepted: 03/25/2018] [Indexed: 12/14/2022] Open
Abstract
The current interest of the scientific community for research in the field of calcium sensing in general and on the calcium-sensing Receptor (CaR) in particular is demonstrated by the still increasing number of papers published on this topic. The extracellular calcium-sensing receptor is the best-known G-protein-coupled receptor (GPCR) able to sense external Ca2+ changes. Widely recognized as a fundamental player in systemic Ca2+ homeostasis, the CaR is ubiquitously expressed in the human body where it activates multiple signalling pathways. In this review, old and new notions regarding the mechanisms by which extracellular Ca2+ microdomains are created and the tools available to measure them are analyzed. After a survey of the main signalling pathways triggered by the CaR, a special attention is reserved for the emerging concepts regarding CaR function in the heart, CaR trafficking and pharmacology. Finally, an overview on other Ca2+ sensors is provided.
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Affiliation(s)
- Andrea Gerbino
- Department of Biosciences, Biotechnology and Biopharmaceutics, University of Bari, 70121 Bari, Italy.
| | - Matilde Colella
- Department of Biosciences, Biotechnology and Biopharmaceutics, University of Bari, 70121 Bari, Italy.
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10
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Kim MJ, Choi KJ, Yoon MN, Oh SH, Kim DK, Kim SH, Park HS. Hydrogen peroxide inhibits Ca 2+ efflux through plasma membrane Ca 2+-ATPase in mouse parotid acinar cells. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2018. [PMID: 29520174 PMCID: PMC5840080 DOI: 10.4196/kjpp.2018.22.2.215] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Intracellular Ca2+ mobilization is closely linked with the initiation of salivary secretion in parotid acinar cells. Reactive oxygen species (ROS) are known to be related to a variety of oxidative stress-induced cellular disorders and believed to be involved in salivary impairments. In this study, we investigated the underlying mechanism of hydrogen peroxide (H2O2) on cytosolic Ca2+ accumulation in mouse parotid acinar cells. Intracellular Ca2+ levels were slowly elevated when 1 mM H2O2 was perfused in the presence of normal extracellular Ca2+. In a Ca2+-free medium, 1 mM H2O2 still enhanced the intracellular Ca2+ level. Ca2+ entry tested using manganese quenching technique was not affected by perfusion of 1 mM H2O2. On the other hand, 10 mM H2O2 induced more rapid Ca2+ accumulation and facilitated Ca2+ entry from extracellular fluid. Ca2+ refill into intracellular Ca2+ store and inositol 1,4,5-trisphosphate (1 µM)-induced Ca2+ release from Ca2+ store was not affected by 1 mM H2O2 in permeabilized cells. Ca2+ efflux through plasma membrane Ca2+-ATPase (PMCA) was markedly blocked by 1 mM H2O2 in thapsigargin-treated intact acinar cells. Antioxidants, either catalase or dithiothreitol, completely protected H2O2-induced Ca2+ accumulation through PMCA inactivation. From the above results, we suggest that excessive production of H2O2 under pathological conditions may lead to cytosolic Ca2+ accumulation and that the primary mechanism of H2O2-induced Ca2+ accumulation is likely to inhibit Ca2+ efflux through PMCA rather than mobilize Ca2+ ions from extracellular medium or intracellular stores in mouse parotid acinar cells.
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Affiliation(s)
- Min Jae Kim
- Department of Physiology, College of Medicine, Konyang University, Daejeon 35365, Korea
| | - Kyung Jin Choi
- Department of Physiology, College of Medicine, Konyang University, Daejeon 35365, Korea
| | - Mi Na Yoon
- Department of Physiology, College of Medicine, Konyang University, Daejeon 35365, Korea
| | - Sang Hwan Oh
- Department of Dental Hygiene, College of Medical Science, Konyang University, Daejeon 35365, Korea
| | - Dong Kwan Kim
- Department of Physiology, College of Medicine, Konyang University, Daejeon 35365, Korea
| | - Se Hoon Kim
- Department of Physiology, College of Medicine, Konyang University, Daejeon 35365, Korea
| | - Hyung Seo Park
- Department of Physiology, College of Medicine, Konyang University, Daejeon 35365, Korea.,Myunggok Medical Research Institute, Konyang University, Daejeon 35365, Korea
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11
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Peng S, Gerasimenko JV, Tsugorka T, Gryshchenko O, Samarasinghe S, Petersen OH, Gerasimenko OV. Calcium and adenosine triphosphate control of cellular pathology: asparaginase-induced pancreatitis elicited via protease-activated receptor 2. Philos Trans R Soc Lond B Biol Sci 2017; 371:rstb.2015.0423. [PMID: 27377732 PMCID: PMC4938023 DOI: 10.1098/rstb.2015.0423] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/20/2016] [Indexed: 12/16/2022] Open
Abstract
Exocytotic secretion of digestive enzymes from pancreatic acinar cells is elicited by physiological cytosolic Ca2+ signals, occurring as repetitive short-lasting spikes largely confined to the secretory granule region, that stimulate mitochondrial adenosine triphosphate (ATP) production. By contrast, sustained global cytosolic Ca2+ elevations decrease ATP levels and cause necrosis, leading to the disease acute pancreatitis (AP). Toxic Ca2+ signals can be evoked by products of alcohol and fatty acids as well as bile acids. Here, we have investigated the mechanism by which l-asparaginase evokes AP. Asparaginase is an essential element in the successful treatment of acute lymphoblastic leukaemia, the most common type of cancer affecting children, but AP is a side-effect occurring in about 5–10% of cases. Like other pancreatitis-inducing agents, asparaginase evoked intracellular Ca2+ release followed by Ca2+ entry and also substantially reduced Ca2+ extrusion because of decreased intracellular ATP levels. The toxic Ca2+ signals caused extensive necrosis. The asparaginase-induced pathology depended on protease-activated receptor 2 and its inhibition prevented the toxic Ca2+ signals and necrosis. We tested the effects of inhibiting the Ca2+ release-activated Ca2+ entry by the Ca2+ channel inhibitor GSK-7975A. This markedly reduced asparaginase-induced Ca2+ entry and also protected effectively against the development of necrosis. This article is part of the themed issue ‘Evolution brings Ca2+ and ATP together to control life and death’.
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Affiliation(s)
- Shuang Peng
- Cardiff School of Biosciences, Cardiff University, Cardiff CF10 3AX, Wales, UK Department of Pathophysiology, Medical College, Jinan University, Guangzhou 510632, People's Republic of China
| | - Julia V Gerasimenko
- Cardiff School of Biosciences, Cardiff University, Cardiff CF10 3AX, Wales, UK
| | - Tatiana Tsugorka
- Cardiff School of Biosciences, Cardiff University, Cardiff CF10 3AX, Wales, UK
| | - Oleksiy Gryshchenko
- Cardiff School of Biosciences, Cardiff University, Cardiff CF10 3AX, Wales, UK Bogomoletz Institute of Physiology, Kiev 01024, Ukraine
| | - Sujith Samarasinghe
- Great Ormond Street Hospital for Children NHS Foundation Trust, Great Ormond Street, London WC1N 3JH, UK
| | - Ole H Petersen
- Cardiff School of Biosciences, Cardiff University, Cardiff CF10 3AX, Wales, UK Systems Immunity Research Institute, Cardiff University, Cardiff CF14 4XN, Wales, UK
| | - Oleg V Gerasimenko
- Cardiff School of Biosciences, Cardiff University, Cardiff CF10 3AX, Wales, UK
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12
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Petersen OH, Courjaret R, Machaca K. Ca 2+ tunnelling through the ER lumen as a mechanism for delivering Ca 2+ entering via store-operated Ca 2+ channels to specific target sites. J Physiol 2017; 595:2999-3014. [PMID: 28181236 PMCID: PMC5430212 DOI: 10.1113/jp272772] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Accepted: 01/05/2017] [Indexed: 01/02/2023] Open
Abstract
Ca2+ signalling is perhaps the most universal and versatile mechanism regulating a wide range of cellular processes. Because of the many different calcium‐binding proteins distributed throughout cells, signalling precision requires localized rises in the cytosolic Ca2+ concentration. In electrically non‐excitable cells, for example epithelial cells, this is achieved by primary release of Ca2+ from the endoplasmic reticulum via Ca2+ release channels placed close to the physiological target. Because any rise in the cytosolic Ca2+ concentration activates Ca2+ extrusion, and in order for cells not to run out of Ca2+, there is a need for compensatory Ca2+ uptake from the extracellular fluid. This Ca2+ uptake occurs through a process known as store‐operated Ca2+ entry. Ideally Ca2+ entering the cell should not diffuse to the target site through the cytosol, as this would potentially activate undesirable processes. Ca2+ tunnelling through the lumen of the endoplasmic reticulum is a mechanism for delivering Ca2+ entering via store‐operated Ca2+ channels to specific target sites, and this process has been described in considerable detail in pancreatic acinar cells and oocytes. Here we review the most important evidence and present a generalized concept.
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Affiliation(s)
- Ole H Petersen
- MRC Group, School of Biosciences and Systems Immunity Research Institute, Cardiff University, Cardiff, CF10 3AX, UK
| | - Raphael Courjaret
- Department of Physiology and Biophysics, Weill Cornell Medicine Qatar, Education City, Qatar Foundation, PO Box 24144, Doha, Qatar
| | - Khaled Machaca
- Department of Physiology and Biophysics, Weill Cornell Medicine Qatar, Education City, Qatar Foundation, PO Box 24144, Doha, Qatar
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13
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Colella M, Gerbino A, Hofer AM, Curci S. Recent advances in understanding the extracellular calcium-sensing receptor. F1000Res 2016; 5. [PMID: 27803801 PMCID: PMC5074356 DOI: 10.12688/f1000research.8963.1] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 10/13/2016] [Indexed: 12/11/2022] Open
Abstract
The extracellular calcium-sensing receptor (CaR), a ubiquitous class C G-protein-coupled receptor (GPCR), is responsible for the control of calcium homeostasis in body fluids. It integrates information about external Ca
2+ and a surfeit of other endogenous ligands into multiple intracellular signals, but how is this achieved? This review will focus on some of the exciting concepts in CaR signaling and pharmacology that have emerged in the last few years.
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Affiliation(s)
- Matilde Colella
- Department of Biosciences, Biotechnology and Biopharmaceutics, University of Bari , Bari, Italy
| | - Andrea Gerbino
- Department of Biosciences, Biotechnology and Biopharmaceutics, University of Bari , Bari, Italy
| | - Aldebaran M Hofer
- Department of Surgery, Brigham & Women's Hospital, Harvard Medical School and VA Boston Healthcare System, West Roxbury, MA, USA
| | - Silvana Curci
- Department of Surgery, Brigham & Women's Hospital, Harvard Medical School and VA Boston Healthcare System, West Roxbury, MA, USA
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14
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Petersen OH. Calcium signalling and secretory epithelia. Cell Calcium 2014; 55:282-9. [PMID: 24508392 DOI: 10.1016/j.ceca.2014.01.003] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2013] [Accepted: 01/10/2014] [Indexed: 12/15/2022]
Abstract
Ca(2+) is now firmly established as the most important intracellular regulator of physiological and pathological events in a vast number of different cell types, including secretory epithelia. In these tissues, Ca(2+) signalling is crucially important for the control of both fluid secretion and electrolyte secretion as well as the regulation of macromolecule secretion. In this overview article, I shall attempt to give some general background to the concepts underlying our current thinking about Ca(2+) signalling in epithelia and its roles in regulating secretion. It is outside the scope of this review to provide a comprehensive account of Ca(2+) signalling and the many different processes in the many different secretory epithelia that are controlled by Ca(2+) signals. It is my aim to draw attention to some general features of Ca(2+) signalling processes in secretory epithelia, which are rather different from those in, for example, endocrine glands. The principal examples will be taken from studies of exocrine cells and, in particular, pancreatic acinar cells, as they are the pioneer cells with regard to investigations of Ca(2+) signalling due to primary intracellular Ca(2+) release. They also represent the cell type which has been characterized in most detail with regard to Ca(2+) transport events and mechanisms.
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Affiliation(s)
- O H Petersen
- MRC Secretory Control Research Group, Cardiff School of Biosciences, Cardiff University, The Sir Martin Evans Building, Museum Avenue, Cardiff CF10 3AX, Wales, UK.
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15
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Al-Dossary AA, Strehler EE, Martin-DeLeon PA. Expression and secretion of plasma membrane Ca2+-ATPase 4a (PMCA4a) during murine estrus: association with oviductal exosomes and uptake in sperm. PLoS One 2013; 8:e80181. [PMID: 24244642 PMCID: PMC3828235 DOI: 10.1371/journal.pone.0080181] [Citation(s) in RCA: 116] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Accepted: 10/09/2013] [Indexed: 12/02/2022] Open
Abstract
PMCA4, a membrane protein, is the major Ca2+ efflux pump in murine sperm where its deletion leads to a severe loss of hyperactivated motility and to male infertility. We have previously shown that the PMCA4b splice variant interacts with CASK (Ca2+/CaM-dependent serine kinase) in regulating sperm Ca2+. More recently we detected that PMCA4a isoform, in addition to its presence in testis, is secreted in the epididymal luminal fluid and transferred to sperm. Here we show that Pmca4 mRNA is expressed in both the 4a and 4b variants in the vagina, uterus, and oviduct. Immunofluorescence reveals that PMCA4a is similarly expressed and is elevated during estrus, appearing in the glandular and luminal epithelia. Western analysis detected PMCA4a in all tissues and in the luminal fluids (LF) of the vagina (VLF), uterus (ULF), and the oviduct (OLF) collected during estrus. It was ~9- and 4-fold higher in OLF than in VLF and ULF, and only marginally present in LF collected at metestrus/diestrus. Fractionation of the LF collected at estrus, via ultracentrifugation, revealed that 100% of the PMCA4a resides in the vesicular fraction of the ULF and OLF. Transmission electron microscopy (TEM) revealed that OLF vesicles have an exosomal orientation (with the cytoplasmic-side inward), a size range of 25-100 nm, with the characteristic CD9 biomarker. Thus, we dubbed these vesicles “oviductosomes”, to which PMCA4a was immunolocalized. Incubation of caudal sperm in the combined LF or exosomes resulted in up to a ~3-fold increase of sperm PMCA4a, as detected by flow cytometry, indicating in vitro uptake. Our results are consistent with the increased requirement of Ca2+ efflux in the oviduct. They show for the first time the presence of oviductal exosomes and highlight their role, along with uterosomes and vaginal exosomes, in post-testicular sperm acquisition of PMCA4a which is essential for hyperactivated motility and fertility.
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Affiliation(s)
- Amal A. Al-Dossary
- Department of Biological Sciences, University of Delaware, Newark, Delaware, United States of America
| | - Emanuel E. Strehler
- Department of Biochemistry, Mayo Clinic, Rochester, Minnesota, United States of America
| | - Patricia A. Martin-DeLeon
- Department of Biological Sciences, University of Delaware, Newark, Delaware, United States of America
- * E-mail:
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16
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Patel R, Al-Dossary AA, Stabley DL, Barone C, Galileo DS, Strehler EE, Martin-DeLeon PA. Plasma membrane Ca2+-ATPase 4 in murine epididymis: secretion of splice variants in the luminal fluid and a role in sperm maturation. Biol Reprod 2013; 89:6. [PMID: 23699388 DOI: 10.1095/biolreprod.113.108712] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Plasma membrane Ca(2+)-ATPase isoform 4 (PMCA4) is the primary Ca(2+) efflux pump in murine sperm, where it regulates motility. In Pmca4 null sperm, motility loss results in infertility. We have shown that murine sperm PMCA4b interacts with Ca(2+)/CaM-dependent serine kinase (CASK) in regulating Ca(2+) homeostasis and motility. However, recent work indicated that the bovine PMCA4a splice variant (missing in testis) is epididymally expressed, along with 4b, and may be transferred to sperm. Here we show, via conventional and in situ RT-PCR, that both the splice variants of Pmca4 mRNA are expressed in murine testis and throughout the epididymis. Immunofluorescence localized PMCA4a to the apical membrane of the epididymal epithelium, and Western analysis not only confirmed its presence but showed for the first time that PMCA4a and PMCA4b are secreted in the epididymal luminal fluid (ELF), from which epididymosomes containing PMCA4a were isolated. Flow cytometry indicated the presence of PMCA4a on mature caudal sperm where it was increased ~5-fold compared to caput sperm (detected by Western blotting) and ~2-fold after incubation in ELF, revealing in vitro uptake and implicating PMCA4a in epididymal sperm maturation. Coimmunoprecipitation using pan-PMCA4 antibodies, revealed that both variants associate with CASK, suggesting their presence in a complex. Because they have different kinetic properties for Ca(2+) transport and different abilities to bind to CASK, our study suggests a mechanism for combining the functional attributes of both PMCA4 variants, leading to heightened efficiency of the pump in the maintenance of Ca(2+) homeostasis, which is crucial for normal motility and male fertility.
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Affiliation(s)
- Ramkrishna Patel
- Department of Biological Sciences, University of Delaware, Newark, DE 19716, USA
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17
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Petersen OH. Specific mitochondrial functions in separate sub-cellular domains of pancreatic acinar cells. Pflugers Arch 2012; 464:77-87. [PMID: 22491894 DOI: 10.1007/s00424-012-1099-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2012] [Accepted: 03/14/2012] [Indexed: 01/06/2023]
Abstract
The pancreatic acinar cell synthesizes many digestive proenzymes, which are packaged into secretory (zymogen) granules and secreted by exocytosis upon the action of the neurotransmitter acetylcholine, released from vagal nerve endings, or the hormone cholecystokinin. These secretagogues mobilize Ca(2+) from internal stores and thereby create the cytosolic Ca(2+) signals that control exocytosis. Exocytosis requires Ca(2+), Mg(2+) and ATP. Mg(2+) is present in millimolars concentration throughout the cytosol, but high cytosolic Ca(2+) concentrations need to be created in the local domains near the apical plasma membrane. A special group of mitochondria surrounding the apical granular area play a crucial role in confining cytosolic Ca(2+) elevations to this part of the cell by acting as a Ca(2+) buffer barrier. The Ca(2+) uptake into these mitochondria during apical Ca(2+) spiking stimulates mitochondrial ATP synthesis. ATP is also required for Ca(2+) extrusion via the plasma membrane Ca(2+) pumps, mainly located in the apical area, as well as for Ca(2+) reuptake into the endoplasmic reticulum. Because Ca(2+) extrusion occurs during Ca(2+) spiking, there is a need for compensatory Ca(2+) entry via store-operated Ca(2+) channels. Sub-plasmalemmal (peripheral) mitochondria play an important role in supporting both store-operated Ca(2+) entry at the base as well as the subsequent Ca(2+) pumping into the endoplasmic reticulum. A third group of mitochondria surround the nucleus. They protect the nucleus against unwarranted Ca(2+) signals generated elsewhere and are capable of confining Ca(2+) signals primarily generated inside the nucleus to this part of the cell.
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Affiliation(s)
- Ole H Petersen
- MRC Group, School of Biosciences, Cardiff University, Biomedical Sciences Building, Museum Avenue, Cardiff, CF10 3AX, Wales, UK.
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Ma HT, Beaven MA. Regulators of Ca(2+) signaling in mast cells: potential targets for treatment of mast cell-related diseases? ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2011; 716:62-90. [PMID: 21713652 DOI: 10.1007/978-1-4419-9533-9_5] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
A calcium signal is essential for degranulation, generation of eicosanoids and optimal production of cytokines in mast cells in response to antigen and other stimulants. The signal is initiated by phospholipase C-mediated production of inositol1,4,5-trisphosphate resulting in release of stored Ca(2+) from the endoplasmic reticulum (ER) and Golgi. Depletion of these stores activates influx of extracellular Ca(2+), usually referred to as store-operated calcium entry (SOCE), through the interaction of the Ca(2+)-sensor, stromal interacting molecule-1 (STIM1 ), in ER with Orai1(CRACM1) and transient receptor potential canonical (TRPC) channel proteins in the plasma membrane (PM). This interaction is enabled by microtubular-directed reorganization of ER to form ER/PM contact points or "punctae" in which STIM1 and channel proteins colocalize. The ensuing influx of Ca(2+) replenishes Ca(2+) stores and sustains elevated levels of cytosolic Ca(2+) ions-the obligatory signal for mast-cell activation. In addition, the signal can acquire spatial and dynamic characteristics (e.g., calcium puffs, waves, oscillations) that encode signals for specific functional outputs. This is achieved by coordinated regulation of Ca(2+) fluxes through ATP-dependent Ca(2+)-pumps and ion exchangers in mitochondria, ER and PM. As discussed in this chapter, studies in mast cells revealed much about the mechanisms described above but little about allergic and autoimmune diseases although studies in other types of cells have exposed genetic defects that lead to aberrant calcium signaling in immune diseases. Pharmacologic agents that inhibit or activate the regulatory components of calcium signaling in mast cells are also discussed along with the prospects for development of novel SOCE inhibitors that may prove beneficial in the treatment inflammatory mast-cell related diseases.
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Affiliation(s)
- Hong-Tao Ma
- Laboratory of Molecular Immunology, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA
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19
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Abstract
Orai1 proteins have been recently identified as subunits of SOCE (store-operated Ca2+ entry) channels. In primary isolated PACs (pancreatic acinar cells), Orai1 showed remarkable co-localization and co-immunoprecipitation with all three subtypes of IP3Rs (InsP3 receptors). The co-localization between Orai1 and IP3Rs was restricted to the apical part of PACs. Neither co-localization nor co-immunoprecipitation was affected by Ca2+ store depletion. Importantly we also characterized Orai1 in basal and lateral membranes of PACs. The basal and lateral membranes of PACs have been shown previously to accumulate STIM1 (stromal interaction molecule 1) puncta as a result of Ca2+ store depletion. We therefore conclude that these polarized secretory cells contain two pools of Orai1: an apical pool that interacts with IP3Rs and a basolateral pool that interacts with STIM1 following the Ca2+ store depletion. Experiments on IP3R knockout animals demonstrated that the apical Orai1 localization does not require IP3Rs and that IP3Rs are not necessary for the activation of SOCE. However, the InsP3-releasing secretagogue ACh (acetylcholine) produced a negative modulatory effect on SOCE, suggesting that activated IP3Rs could have an inhibitory effect on this Ca2+ entry mechanism.
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Abstract
Calcium signals mediate diverse cellular functions in immunological cells. Early studies with mast cells, then a preeminent model for studying Ca2+-dependent exocytosis, revealed several basic features of calcium signaling in non-electrically excitable cells. Subsequent studies in these and other cells further defined the basic processes such as inositol 1,4,5-trisphosphate-mediated release of Ca2+ from Ca2+ stores in the endoplasmic reticulum (ER); coupling of ER store depletion to influx of external Ca2+ through a calcium-release activated calcium (CRAC) channel now attributed to the interaction of the ER Ca2+ sensor, stromal interacting molecule-1 (STIM1), with a unique Ca2+-channel protein, Orai1/CRACM1, and subsequent uptake of excess Ca2+ into ER and mitochondria through ATP-dependent Ca2+ pumps. In addition, transient receptor potential channels and ion exchangers also contribute to the generation of calcium signals that may be global or have dynamic (e.g., waves and oscillations) and spatial resolution for specific functional readouts. This review discusses past and recent developments in this field of research, the pharmacologic agents that have assisted in these endeavors, and the mast cell as an exemplar for sorting out how calcium signals may regulate multiple outputs in a single cell.
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Affiliation(s)
- Hong-Tao Ma
- Laboratory of Molecular Immunology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
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Post H, Gutberlet J, Wiche R, Aumüller G, Wilhelm B. The localization of PMCA1b in epithelial cells and aposomes of the rat coagulating gland is influenced by androgens. Prostate 2008; 68:1076-85. [PMID: 18395836 DOI: 10.1002/pros.20769] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
BACKGROUND Rat coagulating gland epithelial cells export proteins by an apocrine secretion mode within membrane blebs arising from the apical plasma membrane. Using a pan-PMCA antibody, we have recently shown the plasma membrane Ca(2+)-ATPase (PMCA) being part of the apical plasma membrane of epithelial cells and incorporated into the aposomal membrane. The mRNA of PMCA isoforms 1 and 4 respectively, have been detected by RT-PCR in rat coagulating gland. METHODS In order to identify which PMCA isoform is integrated into aposomes during apocrine secretion and whether or not PMCA export is influenced by androgens RT-PCR, in situ hybridization, Western blotting, and immunofluorescence experiments were performed. RESULTS PMCA1b is the isoform which is expressed and located in the apical plasma membrane of coagulating gland epithelial cells and is integrated into the aposomal membrane. In contrast, PMCA4 mRNA and protein are restricted to the stroma. Androgen deprivation by castration within 14 days leads to an accumulation of PMCA1b in coagulating gland epithelium, while aposomes are not detected anymore. CONCLUSIONS We showed for the first time that PMCA isoform 1b is released via aposomes of the epithelial cells of the rat coagulating gland and that the localization of PMCA1b in the epithelial cells is influenced by androgens.
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Affiliation(s)
- Heidi Post
- Department of Anatomy and Cell Biology, Philipps-University, Marburg, Germany
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Gerasimenko O, Tepikin A. How to measure Ca2+ in cellular organelles? Cell Calcium 2008; 38:201-11. [PMID: 16102822 DOI: 10.1016/j.ceca.2005.06.025] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2005] [Accepted: 06/28/2005] [Indexed: 11/27/2022]
Abstract
The review will aim to briefly summarise information on calcium measurements in cellular organelles with emphases on studies conducted in live cells using optical probes. When appropriate we will try to compare the effectiveness of different indicators for intraorganellar calcium measurements. We will consider calcium measurements in endoplasmic reticulum, Golgi apparatus, endosomes/lysosomes, nucleoplasm, nuclear envelope, mitochondria and secretory granules.
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Affiliation(s)
- Oleg Gerasimenko
- The Physiological Laboratory, The University of Liverpool, Crown Street, P.O. Box 147, Liverpool L69 3BX, UK
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23
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Petersen OH. Ca2+ signalling and Ca2+-activated ion channels in exocrine acinar cells. Cell Calcium 2008; 38:171-200. [PMID: 16107275 DOI: 10.1016/j.ceca.2005.06.024] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2005] [Accepted: 06/28/2005] [Indexed: 01/11/2023]
Abstract
The development of the calcium signalling field, from its early beginnings some 40 years ago to the present, is described. Calcium signalling in exocrine gland acinar cells and the effects of neurotransmitter- or hormone-elicited rises in the cytosolic calcium ion concentration on ion channel gating are reviewed. The highly polarized arrangement of the organelle systems in living acinar cells is described as well as its importance for the physiologically relevant local and polarized calcium signalling events.
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Affiliation(s)
- Ole H Petersen
- MRC Group, The Physiological Laboratory, University of Liverpool, Crown Street, Liverpool L69 3BX, UK.
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Abstract
Cytosolic Ca2+ signals are crucial for the control of fluid and enzyme secretion from exocrine glands. The highly polarized exocrine acinar cells have evolved sophisticated and complex Ca2+ signaling mechanisms that exercise precise control of the secretory events occurring across the apical plasma membrane bordering the gland lumen. Ca2+ stores in the endoplasmic reticulum, the secretory granules, the lysosomes, and the endosomes all play important roles in the generation of the local apical Ca2+ spikes that switch on Cl(-) channels in the apical plasma membrane as well as exocytotic export of enzymes. The mitochondria are crucial not only for ATP generation but also for the physiologically important subcellular compartmentalization of the cytosolic Ca2+ signals.
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Affiliation(s)
- Ole H Petersen
- MRC Group, The Physiological Laboratory, School of Biomedical Science, University of Liverpool, Liverpool L69 3BX, United Kingdom.
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25
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Shuba YM, Dietrich CJ, Oermann E, Cleemann L, Morad M. Local extracellular acidification caused by Ca2+-dependent exocytosis in PC12 cells. Cell Calcium 2008; 44:220-9. [PMID: 18346783 DOI: 10.1016/j.ceca.2007.12.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2007] [Revised: 11/06/2007] [Accepted: 12/01/2007] [Indexed: 11/26/2022]
Abstract
Exocytosis of acidic synaptic vesicles may produce local extracellular acidification, but this effect has not been measured directly and its magnitude may depend on the geometry and pH-buffering capacity of both the vesicles and the extracellular space. Here we have used SNARF dye immobilized by conjugation to dextran to measure the release of protons from PC12 cells. The PC12 cells were stimulated by exposure to depolarizing K(+)-rich solution and activation was verified by fluorescence measurement of intracellular Ca(2+) and the release kinetics of GFP-labeled vesicles. Confocal imaging of the pH-dependent fluorescence from the immobile extracellular SNARF dye showed transient acidification around the cell bodies and neurites of activated PC12 cells. The local acidification was abolished when extracellular solution was devoid of Ca(2+) or strong pH-buffering was imposed with 10mM of HEPES. We conclude that the release of secretory vesicles induces local rises in proton concentrations that are co-released from synaptic vesicles with the primary neurotransmitter, and propose that the co-released protons may modulate the signaling in confined micro-domains of synapses.
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Affiliation(s)
- Yaroslav M Shuba
- Department of Pharmacology, Georgetown University, Washington, DC 20057, USA
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26
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Breitwieser GE. Extracellular calcium as an integrator of tissue function. Int J Biochem Cell Biol 2008; 40:1467-80. [PMID: 18328773 PMCID: PMC2441573 DOI: 10.1016/j.biocel.2008.01.019] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2007] [Revised: 01/16/2008] [Accepted: 01/18/2008] [Indexed: 12/23/2022]
Abstract
The past several decades of research into calcium signaling have focused on intracellular calcium (Ca(i)(2+)), revealing both exquisite spatial and dynamic control of this potent second messenger. Our understanding of Ca(i)(2+) signaling has benefited from the evolution of cell culture methods, development of high affinity fluorescent calcium indicators (both membrane-permeant small molecules and genetically encoded proteins), and high-resolution fluorescence microscopy. As our understanding of single cell calcium dynamics has increased, translational efforts have attempted to push calcium signaling studies back into tissues, organs and whole animals. Emerging results from these more complicated, diffusion-limited systems have begun to define a role for extracellular calcium (Ca(o)(2+)) as an agonist, spurred by the cloning and characterization of a G protein-coupled receptor activated by Ca(o)(2+) (the calcium sensing receptor, CaR). Here, we review the current state-of-the art for measurement of Ca(o)(2+) fluctuations, and the evidence that fluctuations in Ca(o)(2+) can act as primary signals regulating cell function. Current results suggest that Ca(o)(2+) in bone and epidermis may act as a chemotactic homing signal, targeting cells to the appropriate tissue locations prior to initiation of the differentiation program. Ca(i)(2+) signaling-mediated Ca(o)(2+) fluctuations in interstitial spaces may integrate cell signaling responses in multicellular networks through activation of CaR. Appreciation of the importance of Ca(o)(2+) fluctuations in coordinating cell function will likely spur identification of additional, niche-specific Ca(2+) sensors, and provide unique insights into the regulation of multicellular signaling networks.
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Affiliation(s)
- Gerda E Breitwieser
- Weis Center for Research, Geisinger Clinic, 100 N. Academy Avenue, Danville, PA 17822, United States.
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27
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Expression and localization of PMCA4 in rat testis and epididymis. Histochem Cell Biol 2007; 129:331-43. [DOI: 10.1007/s00418-007-0362-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/14/2007] [Indexed: 10/22/2022]
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Baggaley E, McLarnon S, Demeter I, Varga G, Bruce JIE. Differential regulation of the apical plasma membrane Ca(2+) -ATPase by protein kinase A in parotid acinar cells. J Biol Chem 2007; 282:37678-93. [PMID: 17938178 DOI: 10.1074/jbc.m703416200] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cross-talk between intracellular calcium ([Ca(2+)](i)) signaling and cAMP defines the specificity of stimulus-response coupling in a variety of cells. Previous studies showed that protein kinase A (PKA) potentiates and phosphorylates the plasma membrane Ca(2+)-ATPase (PMCA) in a Ca(2+)-dependent manner in parotid acinar cells (Bruce, J. I. E., Yule, D. I., and Shuttleworth, T. J. (2002) J. Biol. Chem. 277, 48172-48181). The aim of this study was to further investigate the spatial regulation of [Ca(2+)](i) clearance in parotid acinar cells. Par-C10 cells were used to functionally isolate the apical and basolateral PMCA activity by applying La(3+) to the opposite side to inhibit the PMCA. Activation of PKA (using forskolin) differentially potentiated apical [Ca(2+)](i) clearance in mouse parotid acinar cells and apical PMCA activity in Par-C10 cells. Immunofluorescence of parotid tissue slices revealed that PMCA1 was distributed throughout the plasma membrane, PMCA2 was localized to the basolateral membrane, and PMCA4 was localized to the apical membrane of parotid acinar cells. However, in situ phosphorylation assays demonstrated that PMCA1 was the only isoform phosphorylated by PKA following stimulation. Similarly, immunofluorescence of acutely isolated parotid acinar cells showed that the regulatory subunit of PKA (RIIbeta) translocated to the apical region following stimulation. These data suggest that PKA-mediated phosphorylation of PMCA1 differentially regulates [Ca(2+)](i) clearance in the apical region of parotid acinar cells because of a dynamic translocation of PKA. Such tight spatial regulation of Ca(2+) efflux is likely important for the fine-tuning of Ca(2+)-dependent effectors close to the apical membrane important for the regulation of fluid secretion and exocytosis.
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Affiliation(s)
- Erin Baggaley
- Faculty of Life Sciences, the University of Manchester, Manchester, UK
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29
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Ishikawa Y, Cho G, Yuan Z, Skowronski MT, Pan Y, Ishida H. Water channels and zymogen granules in salivary glands. J Pharmacol Sci 2006; 100:495-512. [PMID: 16799262 DOI: 10.1254/jphs.crj06007x] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
Abstract
Salivary secretion occurs in response to stimulation by neurotransmitters released from autonomic nerve endings. The molecular mechanisms underlying the secretion of water, a main component of saliva, from salivary glands are not known; the plasma membrane is a major barrier to water transport. A 28-kDa integral membrane protein, distributed in highly water-permeable tissues, was identified as a water channel protein, aquaporin (AQP). Thirteen AQPs (AQP0 - AQP12) have been identified in mammals. AQP5 is localized in lipid rafts under unstimulated conditions and translocates to the apical plasma membrane in rat parotid glands upon stimulation by muscarinic agonists. The importance of increases in intracellular calcium concentration [Ca(2+)](i) and the nitric oxide synthase and protein kinase G signaling pathway in the translocation of AQP5 is reviewed in section I. Signals generated by the activation of Ca(2+) mobilizing receptors simultaneously trigger and regulate exocytosis. Zymogen granule exocytosis occurs under the control of essential process, stimulus-secretion coupling, in salivary glands. Ca(2+) signaling is a principal signal in both protein and water secretion from salivary glands induced by cholinergic stimulation. On the other hand, the cyclic adenosine monophosphate (cAMP)/cAMP-dependent protein kinase system has a major role in zymogen granule exocytosis without significant increases in [Ca(2+)](i). In section II, the mechanisms underlying the control of salivary protein secretion and its dysfunction are reviewed.
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Affiliation(s)
- Yasuko Ishikawa
- Department of Pharmacology, The University of Tokushima School of Dentistry, Tokushima, Japan.
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30
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Abstract
Stimulus-secretion coupling is an essential process in secretory cells in which regulated exocytosis occurs, including neuronal, neuroendocrine, endocrine, and exocrine cells. While an increase in intracellular Ca(2+) concentration ([Ca(2+)](i)) is the principal signal, other intracellular signals also are important in regulated exocytosis. In particular, the cAMP signaling system is well known to regulate and modulate exocytosis in a variety of secretory cells. Until recently, it was generally thought that the effects of cAMP in regulated exocytosis are mediated by activation of cAMP-dependent protein kinase (PKA), a major cAMP target, followed by phosphorylation of the relevant proteins. Although the involvement of PKA-independent mechanisms has been suggested in cAMP-regulated exocytosis by pharmacological approaches, the molecular mechanisms are unknown. Newly discovered cAMP-GEF/Epac, which belongs to the cAMP-binding protein family, exhibits guanine nucleotide exchange factor activities and exerts diverse effects on cellular functions including hormone/transmitter secretion, cell adhesion, and intracellular Ca(2+) mobilization. cAMP-GEF/Epac mediates the PKA-independent effects on cAMP-regulated exocytosis. Thus cAMP regulates and modulates exocytosis by coordinating both PKA-dependent and PKA-independent mechanisms. Localization of cAMP within intracellular compartments (cAMP compartmentation or compartmentalization) may be a key mechanism underlying the distinct effects of cAMP in different domains of the cell.
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Affiliation(s)
- Susumu Seino
- Division of Cellular and Molecular Medicine, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan.
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31
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Abstract
Ca(2+) is an essential ion in all organisms, where it plays a crucial role in processes ranging from the formation and maintenance of the skeleton to the temporal and spatial regulation of neuronal function. The Ca(2+) balance is maintained by the concerted action of three organ systems, including the gastrointestinal tract, bone, and kidney. An adult ingests on average 1 g Ca(2+) daily from which 0.35 g is absorbed in the small intestine by a mechanism that is controlled primarily by the calciotropic hormones. To maintain the Ca(2+) balance, the kidney must excrete the same amount of Ca(2+) that the small intestine absorbs. This is accomplished by a combination of filtration of Ca(2+) across the glomeruli and subsequent reabsorption of the filtered Ca(2+) along the renal tubules. Bone turnover is a continuous process involving both resorption of existing bone and deposition of new bone. The above-mentioned Ca(2+) fluxes are stimulated by the synergistic actions of active vitamin D (1,25-dihydroxyvitamin D(3)) and parathyroid hormone. Until recently, the mechanism by which Ca(2+) enter the absorptive epithelia was unknown. A major breakthrough in completing the molecular details of these pathways was the identification of the epithelial Ca(2+) channel family consisting of two members: TRPV5 and TRPV6. Functional analysis indicated that these Ca(2+) channels constitute the rate-limiting step in Ca(2+)-transporting epithelia. They form the prime target for hormonal control of the active Ca(2+) flux from the intestinal lumen or urine space to the blood compartment. This review describes the characteristics of epithelial Ca(2+) transport in general and highlights in particular the distinctive features and the physiological relevance of the new epithelial Ca(2+) channels accumulating in a comprehensive model for epithelial Ca(2+) absorption.
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Affiliation(s)
- Joost G J Hoenderop
- Department of Physiology, Nijmegen Center for Moecular Life Sciences, University Medical Center Nijmegen, The Netherlands
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Fischer L, Gukovskaya AS, Young SH, Gukovsky I, Lugea A, Buechler P, Penninger JM, Friess H, Pandol SJ. Phosphatidylinositol 3-kinase regulates Ca2+ signaling in pancreatic acinar cells through inhibition of sarco(endo)plasmic reticulum Ca2+-ATPase. Am J Physiol Gastrointest Liver Physiol 2004; 287:G1200-12. [PMID: 15271649 DOI: 10.1152/ajpgi.00212.2004] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Calcium is a key mediator of hormone-induced enzyme secretion in pancreatic acinar cells. At the same time, abnormal Ca(2+) responses are associated with pancreatitis. We have recently shown that inhibition of phosphatidylinositol 3-kinase (PI3-kinase) by LY-294002 and wortmannin, as well as genetic deletion of PI3-kinase-gamma, regulates Ca(2+) responses and the Ca(2+)-sensitive trypsinogen activation in pancreatic acinar cells. The present study sought to determine the mechanisms of PI3-kinase involvement in Ca(2+) responses induced in these cells by CCK and carbachol. The PI3-kinase inhibitors inhibited both Ca(2+) influx and mobilization from intracellular stores induced by stimulation of acini with physiological and pathological concentrations of CCK, as well as with carbachol. PI3-kinase inhibition facilitated the decay of cytosolic free Ca(2+) concentration ([Ca(2+)](i)) oscillations observed in individual acinar cells. The PI3-kinase inhibitors decreased neither CCK-induced inositol 1,4,5-trisphosphate [Ins(1,4,5)P(3)] production nor Ins(1,4,5)P(3)-induced Ca(2+) mobilization, suggesting that the effect of PI3-kinase inhibition is not through Ins(1,4,5)P(3) or Ins(1,4,5)P(3) receptors. PI3-kinase inhibition did not affect Ca(2+) mobilization induced by thapsigargin, a specific inhibitor of sarco(endo)plasmic reticulum Ca(2+)-ATPase (SERCA). Moreover, SERCA blockade with thapsigargin abolished the effects of pharmacological and genetic PI3-kinase inhibition on [Ca(2+)](i) signals, suggesting SERCA as a downstream target of PI3-kinase. Both pharmacological PI3-kinase inhibition and genetic deletion of PI3-kinase-gamma increased the amount of Ca(2+) in intracellular stores during CCK stimulation. Finally, addition of the PI3-kinase product phosphatidylinositol 3,4,5-trisphosphate to permeabilized acini significantly attenuated Ca(2+) reloading into the endoplasmic reticulum. The results indicate that PI3-kinase regulates Ca(2+) signaling in pancreatic acinar cells through its inhibitory effect on SERCA.
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Affiliation(s)
- L Fischer
- Veterans Affairs Greater Los Angeles Healthcare System, Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA 90073, USA
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Caroppo R, Gerbino A, Fistetto G, Colella M, Debellis L, Hofer AM, Curci S. Extracellular calcium acts as a "third messenger" to regulate enzyme and alkaline secretion. ACTA ACUST UNITED AC 2004; 166:111-9. [PMID: 15240573 PMCID: PMC2172151 DOI: 10.1083/jcb.200310145] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
It is generally assumed that the functional consequences of stimulation with Ca2+-mobilizing agonists are derived exclusively from the second messenger action of intracellular Ca2+, acting on targets inside the cells. However, during Ca2+ signaling events, Ca2+ moves in and out of the cell, causing changes not only in intracellular Ca2+, but also in local extracellular Ca2+. The fact that numerous cell types possess an extracellular Ca2+ “sensor” raises the question of whether these dynamic changes in external [Ca2+] may serve some sort of messenger function. We found that in intact gastric mucosa, the changes in extracellular [Ca2+] secondary to carbachol-induced increases in intracellular [Ca2+] were sufficient and necessary to elicit alkaline secretion and pepsinogen secretion, independent of intracellular [Ca2+] changes. These findings suggest that extracellular Ca2+ can act as a “third messenger” via Ca2+ sensor(s) to regulate specific subsets of tissue function previously assumed to be under the direct control of intracellular Ca2+.
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Affiliation(s)
- Rosa Caroppo
- Dipartimento di Fisiologia Generale ed Ambientale, Università di Bari, Italy
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Chin WC, Orellana MV, Quesada I, Verdugo P. Secretion in unicellular marine phytoplankton: demonstration of regulated exocytosis in Phaeocystis globosa. PLANT & CELL PHYSIOLOGY 2004; 45:535-542. [PMID: 15169935 DOI: 10.1093/pcp/pch062] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Almost half of the global photosynthetic activity is carried out in the ocean. During blooms, Phaeocystis can fix CO(2) at rates up to 40 g C m(-2) month(-1). Most of this carbon is released as polysaccharides. However, the cellular mechanism whereby this huge amount of organic material is exported into the seawater remains unknown. A vaguely defined process of "exudation" is believed responsible for the release of these biopolymers. Here we report the first demonstration that Phaeocystis globosa does not "exude", but secretes microscopic gels. Secretion is stimulated by blue light (lambda = 470+/-20 nm), and it is transduced by a characteristic intracellular Ca(2+) signal that precedes degranulation. The polysaccharides that form the matrix of these gels remain in condensed phase while stored in secretory vesicles. Upon exocytosis, the exopolymer matrix undergoes a characteristic phase transition accompanied by extensive swelling resulting in the formation of microscopic hydrated gels. Owing to their tangled topology, once released into the seawater, the polymers that make these gels can reptate (axially diffuse), interpenetrate neighboring gels, and anneal them together forming massive mucilage accumulations that are characteristic of Phaeocystis blooms. These gel masses can supply a rich source of microbial substrates, disperse in the seawater, and/or eventually sediment to the ocean floor.
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Affiliation(s)
- Wei-Chun Chin
- Department of Chemical Engineering, FAMU/FSU, Tallahassee, FL 32310, USA
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Park MK, Lee M, Petersen OH. Morphological and functional changes of dissociated single pancreatic acinar cells: testing the suitability of the single cell as a model for exocytosis and calcium signaling. Cell Calcium 2004; 35:367-79. [PMID: 15036953 DOI: 10.1016/j.ceca.2003.10.003] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2003] [Revised: 10/12/2003] [Accepted: 10/16/2003] [Indexed: 11/23/2022]
Abstract
Isolated single pancreatic acinar cells have long been used as a model for studying many kinds of signaling processes due to their structural and functional polarities, but without significant validation. In this study, we examined the morphological and functional changes of dissociated single pancreatic acinar cells. Acutely isolated single cells showed a collapsed membrane potential and a much reduced secretion of zymogen granules in response to acetylcholine (ACh) stimulation, whereas clustered cells showed a much more negative membrane potential and potent exocytotic secretion. The isolated single cells became vertically flattened due to the loss of supporting adhesions with nearby cells, and the granule-attached luminal membrane was severely reduced versus that of clustered cells. However, polarized Ca(2+) signals and mitochondrial localizations were relatively well preserved in the isolated single cells, in that Ca(2+) release by ACh commenced at the indented luminal membrane. In clusters, the Ca(2+) release site was closest to the lumen where more than three cells met or at the tips of conical regions of the luminal membrane. These findings suggest that the dissociated single pancreatic acinar cells preserve an intact Ca(2+) signaling machinery but alter in shape and have impaired exocytotic functions and resting membrane potentials.
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Affiliation(s)
- Myoung Kyu Park
- Medical Research Center for Regulation of Neuronal Cell Excitability and Department of Physiology, Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine, Jangan-ku, Suwon, 440-746, South Korea.
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36
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Zanello LP, Norman AW. Rapid modulation of osteoblast ion channel responses by 1alpha,25(OH)2-vitamin D3 requires the presence of a functional vitamin D nuclear receptor. Proc Natl Acad Sci U S A 2004; 101:1589-94. [PMID: 14757825 PMCID: PMC341781 DOI: 10.1073/pnas.0305802101] [Citation(s) in RCA: 132] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
1alpha,25(OH)(2)-Vitamin D(3) (1,25D) modulates osteoblast gene expression of bone matrix proteins via a nuclear vitamin D receptor (VDR) and also modifies the electrical state of the plasma membrane through rapid nongenomic mechanisms still not fully understood. The physiological significance of 1,25D membrane-initiated effects remains unclear. To elucidate whether the VDR is required for 1,25D-promoted electrical responses, we studied 1,25D modulation of ion channel activities in calvarial osteoblasts isolated from VDR knockout (KO) and WT mice. At depolarizing potentials, Cl(-) currents were significantly potentiated (13.5 +/- 1.6-fold increase, n = 12) by 5 nM 1,25D in VDR WT but not in KO (0.96 +/- 0.3 fold increase, n = 11) osteoblasts. L-type Ca(2+) currents significantly shift their peak activation by -9.3 +/- 0.7 mV (n = 10) in the presence of 5 nM 1,25D in VDR WT but not in KO cells, thus facilitating Ca(2+) influx. Furthermore, we found that 1,25D significantly increased whole-cell capacitance in VDR WT (DeltaCap = 2.3 +/- 0.4 pF, n = 8) but not in KO osteoblasts (DeltaCap = 0.3 +/- 0.1 pF, n = 8); this corresponds to a rapid (1-2 min) fusion in WT of 71 +/- 33 versus in KO only 9 +/- 6 individual secretory granules. We conclude that, in calvarial osteoblasts, 1,25D modulates ion channel activities only in cells with a functional VDR and that this effect is coupled to exocytosis. This is a demonstration of the requirement of a functional classic steroid receptor for the rapid hormonal modulation of electric currents linked to secretory activities in a target cell.
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Affiliation(s)
- Laura P Zanello
- Department of Biochemistry, University of California, Riverside, CA 92521
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37
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Sutton R, Criddle D, Raraty MGT, Tepikin A, Neoptolemos JP, Petersen OH. Signal transduction, calcium and acute pancreatitis. Pancreatology 2003; 3:497-505. [PMID: 14673201 DOI: 10.1159/000075581] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Evidence consistently suggests that the earliest changes of acute pancreatitis are intracellular, the hallmark of which is premature intracellular activation of digestive zymogens, accompanied by disruption of normal signal transduction and secretion. Principal components of physiological signal transduction include secretagogue-induced activation of G-protein-linked receptors, followed by generation of inositol 1,4,5-trisphosphate, nicotinic acid adenine dinucleotide phosphate and cyclic ADP-ribose. In response, calcium is released from endoplasmic reticulum terminals within the apical, granular pole of the cell, where calcium signals are usually contained by perigranular mitochondria, in turn responding by increased metabolism. When all three intracellular messengers are administered together, even at threshold concentrations, dramatic potentiation results in sustained, global, cytosolic calcium elevation. Prolonged, global elevation of cytosolic calcium is also induced by hyperstimulation, bile salts, alcohol and fatty acid ethyl esters, and depends on continued calcium entry into the cell. Such abnormal calcium signals induce intracellular activation of digestive enzymes, and of nuclear factor kappaB, as well as the morphological changes of acute pancreatitis. Depletion of endoplasmic reticulum calcium and mitochondrial membrane potential may contribute to further cell injury. This review outlines current understanding of signal transduction in the pancreas, and its application to the pathophysiology of acute pancreatitis.
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Affiliation(s)
- Robert Sutton
- Department of Surgery, University of Liverpool, 5th Floor UCD Block, Royal Liverpool University Hospital, Daulby Street, Liverpool L69 3GA, UK.
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Abstract
An impressive array of cytosolic calcium ([Ca2+](i)) signals exert control over a broad range of physiological processes. The specificity and fidelity of these [Ca2+](i) signals is encoded by the frequency, amplitude, and sub-cellular localization of the response. It is believed that the distinct characteristics of [Ca2+](i) signals underlies the differential activation of effectors and ultimately cellular events. This "shaping" of [Ca2+](i) signals can be achieved by the influence of additional signaling pathways modulating the molecular machinery responsible for generating [Ca2+](i) signals. There is a particularly rich source of potential sites of crosstalk between the cAMP and the [Ca2+](i) signaling pathways. This review will focus on the predominant molecular loci at which these classical signaling systems interact to impact the spatio-temporal pattern of [Ca2+](i) signaling in non-excitable cells.
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Affiliation(s)
- Jason I E Bruce
- Department of Pharmacology & Physiology, School of Medicine and Dentistry, University of Rochester Medical Center, 601 Elmwood Avenue, Rochester, NY 14642, USA.
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Abstract
Studies of Ca2+ transport pathways in exocrine gland cells have been useful, chiefly because of the polarized nature of the secretory epithelial cells. In pancreatic acinar cells, for example, Ca2+ reloading of empty intracellular stores can occur solely via Ca2+ entry through the basal part of the plasma membrane. On the other hand, the principal site for intracellular Ca2+ release-with the highest concentration of inositol 1,4,5-trisphosphate (IP(3)) receptors-is in the apical secretory pole close to the apical plasma membrane. This apical part of the plasma membrane contains the highest density of Ca2+ pumps and is therefore the principal site for Ca2+ extrusion. On the basis of the known properties of Ca2+ entry and exit pathways in exocrine gland cells, the mechanisms controlling Ca2+ exit and entry are discussed in relation to recent direct information about Ca2+ transport into and out of the endoplasmic reticulum (ER) and the mitochondria in these cells.
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Affiliation(s)
- Ole H Petersen
- MRC Secretory Control Research Group, The Physiological Laboratory, University of Liverpool, Liverpool L69 3BX, UK.
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Papp S, Dziak E, Michalak M, Opas M. Is all of the endoplasmic reticulum created equal? The effects of the heterogeneous distribution of endoplasmic reticulum Ca2+-handling proteins. J Cell Biol 2003; 160:475-9. [PMID: 12591911 PMCID: PMC2173736 DOI: 10.1083/jcb.200207136] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
The endoplasmic reticulum is a heterogeneous compartment with respect to the distribution of its Ca2+-handling proteins, namely the Ca2+-binding proteins, the Ca2+ pumps and the Ca2+ release channels. The nonuniform distribution of these proteins may explain the functional heterogeneity of the endoplasmic reticulum, such as the generation of spatially complex Ca2+ signals, Ca2+ homeostasis, and protein folding and quality control.
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Affiliation(s)
- S Papp
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada M5S 1A8.
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41
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Bruce JIE, Yule DI, Shuttleworth TJ. Ca2+-dependent protein kinase--a modulation of the plasma membrane Ca2+-ATPase in parotid acinar cells. J Biol Chem 2002; 277:48172-81. [PMID: 12368283 DOI: 10.1074/jbc.m208393200] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cross-talk between cAMP and [Ca(2+)](i) signaling pathways represents a general feature that defines the specificity of stimulus-response coupling in a variety of cell types including parotid acinar cells. We have reported recently that cAMP potentiates Ca(2+) release from intracellular stores, primarily because of a protein kinase A-mediated phosphorylation of type II inositol 1,4,5-trisphosphate receptors (Bruce, J. I. E., Shuttleworth, T. J. S., Giovannucci, D. R., and Yule, D. I. (2002) J. Biol. Chem. 277, 1340-1348). The aim of the present study was to evaluate the functional and molecular mechanism whereby cAMP regulates Ca(2+) clearance pathways in parotid acinar cells. Following an agonist-induced increase in [Ca(2+)](i) the rate of Ca(2+) clearance, after the removal of the stimulus, was potentiated substantially ( approximately 2-fold) by treatment with forskolin. This effect was prevented completely by inhibition of the plasma membrane Ca(2+)-ATPase (PMCA) with La(3+). PMCA activity, when isolated pharmacologically, was also potentiated ( approximately 2-fold) by forskolin. Ca(2+) uptake into the endoplasmic reticulum of streptolysin-O-permeabilized cells by sarco/endoplasmic reticulum Ca(2+)-ATPase was largely unaffected by treatment with dibutyryl cAMP. Finally, in situ phosphorylation assays demonstrated that PMCA was phosphorylated by treatment with forskolin but only in the presence of carbamylcholine (carbachol). This effect of forskolin was Ca(2+)-dependent, and protein kinase C-independent, as potentiation of PMCA activity and phosphorylation of PMCA by forskolin also occurred when [Ca(2+)](i) was elevated by the sarco/endoplasmic reticulum Ca(2+)-ATPase inhibitor cyclopiazonic acid and was attenuated by pre-incubation with the Ca(2+) chelator, 1,2-bis(o-aminophenoxy) ethane-N,N,N',N'-tetraacetic acid (BAPTA). The present study demonstrates that elevated cAMP enhances the rate of Ca(2+) clearance because of a complex modulation of PMCA activity that involves a Ca(2+)-dependent step. Tight regulation of both Ca(2+) release and Ca(2+) efflux may represent a general feature of the mechanism whereby cAMP improves the fidelity and specificity of Ca(2+) signaling.
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Affiliation(s)
- Jason I E Bruce
- Department of Pharmacology and Physiology, School of Medicine and Dentistry, University of Rochester Medical Center, New York 14642, USA.
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42
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Nakano K, Takeo T, Sato T, Suga S, Eto K, Kadowaki T, Wakui M. Role of mitochondrial NADH shuttle system in acute amylase secretion by acetylcholine from mouse pancreatic acinar cells. TOHOKU J EXP MED 2002; 198:151-62. [PMID: 12597242 DOI: 10.1620/tjem.198.151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Using the mice that lack mitochondrial glycerol-3-phosphate dehydrogenase (mGPDH), a rate limiting enzyme of the glycerol-phosphate NADH shuttle, we investigated the role of the NADH shuttle system in amylase secretion in response to acetylcholine (ACh) in pancreatic acinar cells. The pancreatic acinar cells of mGPDH-deficient mice were not different in histology and immunohistochemistry from those of wild-type mice. In both types of pancreatic acinar cells from wild-type and mGPDH-deficient mice, ACh similarly potentiated amylase secretion, measured in 30 minutes after the ACh stimulation. A 30 minutes pre-treatment of wild-type cells with aminooxyacetate (AOA), an inhibitor of aspartate aminotransferases of the malate-aspartate NADH shuttle, did not change the rate of ACh-induced amylase secretion, measured in the following 30 minutes. In also mGPDH-deficient cells treated with AOA, thus in this situation all mitochondrial NADH shuttles being dysfunctioning, ACh induced amylase release in a similar amount to that in AOA-untreated cells. The basal levels of intracellular Ca2+ concentration ([Ca2+]i), the ACh-stimulated levels of [Ca2+]i and Ca2+ oscillation patterns in response to ACh were similar in wild-type and mGPDH-deficient cells, and the AOA-treatment did not affect these [Ca2+]i responses. The levels of intracellular concentration of ATP before and during stimulation with ACh were similar in wild-type and mGPDH-defficient cells. In only AOA-treated mGPDH-deficient cells, the level of ATP decreased after the ACh stimulation. These results suggest that acute response of amylase secretion to ACh from mouse pancreatic acinar cells does not require simultaneous functioning of the mitochondrial NADH shuttle system, although the supply of intracellular ATP decreases during the ACh stimulation.
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Affiliation(s)
- Kyoko Nakano
- Department of Medical Technology, Hirosaki University School of Health Sciences, Hirosaki 036-8564, Japan.
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43
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Abstract
This review examines polarized calcium and calmodulin signaling in exocrine epithelial cells. The calcium ion is a simple, evolutionarily ancient, and universal second messenger. In exocrine epithelial cells, it regulates essential functions such as exocytosis, fluid secretion, and gene expression. Exocrine cells are structurally polarized, with the apical region usually dedicated to secretion. Recent advances in technology, in particular the development of videoimaging and confocal microscopy, have led to the discovery of polarized, subcellular calcium signals in these cell types. The properties of a rich variety of local and global calcium signals have now been described in secretory epithelial cells. Secretagogues stimulate apical-to-basal waves of calcium in many exocrine cell types, but there are some interesting exceptions to this rule. The shapes of intracellular calcium signals are determined by the distribution of calcium-releasing channels and mechanisms that limit calcium elevation. Polarized distribution of calcium-handling mechanisms also leads to transcellular calcium transport in exocrine epithelial cells. This transport can deliver considerable amounts of calcium into secreted fluids. Multicellular polarized calcium signals can coordinate the activity of many individual cells in epithelial secretory tissue. Certain particularly sensitive cells serve as pacemakers for initiation of intercellular calcium waves. Many calcium signaling pathways involve activation of calmodulin. This ubiquitous protein regulates secretion in exocrine cells and also activates interesting feedback interactions with calcium channels and transporters. Very recently it became possible to directly study polarized calcium-calmodulin reactions and to visualize the process of hormone-induced redistribution of calmodulin in live cells. The structural and functional polarity of secretory epithelia alongside the polarity of its calcium and calmodulin signaling present an interesting lesson in tissue organization.
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Affiliation(s)
- Michael C Ashby
- Medical Research Council Secretory Control Research Group, The Physiological Laboratory, University of Liverpool, Liverpool, United Kingdom
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44
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Camello-Almaraz C, Salido GM, Pariente JA, Camello PJ. Role of mitochondria in Ca(2+) oscillations and shape of Ca(2+) signals in pancreatic acinar cells. Biochem Pharmacol 2002; 63:283-92. [PMID: 11841804 DOI: 10.1016/s0006-2952(01)00830-9] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
We studied the role of mitochondria in Ca(2+) signals in fura-2 loaded exocrine pancreatic acinar cells. Mitochondrial depolarization in response to carbonylcyanide-p-tryfluoromethoxyphenyl hydrazone or rotenone (assessed by confocal microscopy using rhodamine-123) induced a partial but statistically significant reduction in the decay of Ca(2+) signals under different experimental conditions. Spreading of Ca(2+) waves evoked by the pancreatic secretagogue cholecystokinin cholecystokinin octapeptide was accelerated by mitochondrial inhibitors, whereas the cytosolic Ca(2+) concentration ([Ca(2+)](i)) oscillations in response to physiological levels of this hormone were suppressed by rotenone and carbonylcyanide-p-tryfluoromethoxyphenyl hydrazone. Oligomycin, an inhibitor of mitochondrial ATP synthase, did no affect either propagation of calcium waves nor [Ca(2+)](i) oscillations. Individual mitochondria of rhod-2 loaded acinar cells showed heterogeneous matrix Ca(2+) concentration increases in response to oscillatory and maximal levels of cholecystokinin octapeptide. On the other hand, using Ba(2+) for unequivocal study of capacitative calcium entry we found that mitochondrial inhibitors did not affect this process. Our results show that although the role of mitochondria as a Ca(2+) clearing system in exocrine cells is quantitatively secondary, they play an essential role in the spatial propagation of Ca(2+) waves and in the development of [Ca(2+)](i) oscillations.
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Affiliation(s)
- C Camello-Almaraz
- Department of Physiology, Faculty of Veterinary Sciences, University of Extremadura, 10071, Caceres, Spain
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45
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Caroppo R, Gerbino A, Debellis L, Kifor O, Soybel DI, Brown EM, Hofer AM, Curci S. Asymmetrical, agonist-induced fluctuations in local extracellular [Ca(2+)] in intact polarized epithelia. EMBO J 2001; 20:6316-26. [PMID: 11707403 PMCID: PMC125728 DOI: 10.1093/emboj/20.22.6316] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
We recently proposed that extracellular Ca(2+) ions participate in a novel form of intercellular communication involving the extracellular Ca(2+)-sensing receptor (CaR). Here, using Ca(2+)-selective microelectrodes, we directly measured the profile of agonist-induced [Ca(2+)]ext changes in restricted domains near the basolateral or luminal membranes of polarized gastric acid-secreting cells. The Ca(2+)-mobilizing agonist carbachol elicited a transient, La(3+)-sensitive decrease in basolateral [Ca(2+)] (average approximately 250 microM, but as large as 530 microM). Conversely, carbachol evoked an HgCl2-sensitive increase in [Ca(2+)] (average approximately 400 microM, but as large as 520 microM) in the lumen of single gastric glands. Both responses were significantly reduced by pre-treatment with sarco-endoplasmic reticulum Ca(2+) ATPase (SERCA) pump inhibitors or with the intracellular Ca(2+) chelator BAPTA-AM. Immunofluorescence experiments demonstrated an asymmetric localization of plasma membrane Ca(2+) ATPase (PMCA), which appeared to be partially co-localized with CaR and the gastric H(+)/K(+)-ATPase in the apical membrane of the acid-secreting cells. Our data indicate that agonist stimulation results in local fluctuations in [Ca(2+)]ext that would be sufficient to modulate the activity of the CaR on neighboring cells.
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Affiliation(s)
| | | | | | - Olga Kifor
- Dipartimento di Fisiologia Generale ed Ambientale, Università di Bari, Via Amendola 165/A, 70126 Bari, Italy,
Endocrine Hypertension Division, Membrane Biology Program, Department of Medicine and Department of Surgery, Brigham and Women’s Hospital and Boston VA Healthcare System, Harvard Medical School, Boston and West Roxbury, 1400 VFW Parkway, West Roxbury, MA 02132, USA Corresponding author e-mail:
| | - David I. Soybel
- Dipartimento di Fisiologia Generale ed Ambientale, Università di Bari, Via Amendola 165/A, 70126 Bari, Italy,
Endocrine Hypertension Division, Membrane Biology Program, Department of Medicine and Department of Surgery, Brigham and Women’s Hospital and Boston VA Healthcare System, Harvard Medical School, Boston and West Roxbury, 1400 VFW Parkway, West Roxbury, MA 02132, USA Corresponding author e-mail:
| | - Edward M. Brown
- Dipartimento di Fisiologia Generale ed Ambientale, Università di Bari, Via Amendola 165/A, 70126 Bari, Italy,
Endocrine Hypertension Division, Membrane Biology Program, Department of Medicine and Department of Surgery, Brigham and Women’s Hospital and Boston VA Healthcare System, Harvard Medical School, Boston and West Roxbury, 1400 VFW Parkway, West Roxbury, MA 02132, USA Corresponding author e-mail:
| | - Aldebaran M. Hofer
- Dipartimento di Fisiologia Generale ed Ambientale, Università di Bari, Via Amendola 165/A, 70126 Bari, Italy,
Endocrine Hypertension Division, Membrane Biology Program, Department of Medicine and Department of Surgery, Brigham and Women’s Hospital and Boston VA Healthcare System, Harvard Medical School, Boston and West Roxbury, 1400 VFW Parkway, West Roxbury, MA 02132, USA Corresponding author e-mail:
| | - Silvana Curci
- Dipartimento di Fisiologia Generale ed Ambientale, Università di Bari, Via Amendola 165/A, 70126 Bari, Italy,
Endocrine Hypertension Division, Membrane Biology Program, Department of Medicine and Department of Surgery, Brigham and Women’s Hospital and Boston VA Healthcare System, Harvard Medical School, Boston and West Roxbury, 1400 VFW Parkway, West Roxbury, MA 02132, USA Corresponding author e-mail:
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46
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Sorensen CE, Novak I. Visualization of ATP release in pancreatic acini in response to cholinergic stimulus. Use of fluorescent probes and confocal microscopy. J Biol Chem 2001; 276:32925-32. [PMID: 11387334 DOI: 10.1074/jbc.m103313200] [Citation(s) in RCA: 155] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The energy providing substrate ATP can be released from various cells and act extracellularly to regulate the same cells or neighboring cells. However, the pathway for ATP release and the eliciting physiological stimulus are unclear. Recently, we showed that ATP activates P2X and P2Y purinergic receptors on pancreatic ducts. Thus, it was relevant to ask whether the upstream acini could be the source of releasable ATP and what the stimulus might be. We used freshly prepared rat pancreatic acini and applied conventional luminescence measurements of luciferin/luciferase reaction. As a new application of this reaction in confocal microscopy, we monitored luciferin fluorescence as a sign of ATP release by single acini. In addition we used quinacrine to mark ATP stores, which were similar to those marked with fluorescent ATP, 2'-(or-3')-O-(N-methylanthraniloyl) adenosine 5'-triphosphate, but only partially overlapping with those marked by acridine orange and LysoTracker Red. In functional studies we show that native pancreatic acini release ATP in response to various stimuli but most importantly to cholinergic stimulation, a very likely physiological stimulus in this epithelium. In a close vicinity of acini we detect about 9 microm ATP after cholinergic stimulation. Thus, ATP is poised as the paracrine mediator between pancreatic acini and ducts.
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Affiliation(s)
- C E Sorensen
- August Krogh Institute, Universitetsparken 13, University of Copenhagen, DK-2100 Copenhagen Ø, Denmark
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47
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Williams JA. Intracellular signaling mechanisms activated by cholecystokinin-regulating synthesis and secretion of digestive enzymes in pancreatic acinar cells. Annu Rev Physiol 2001; 63:77-97. [PMID: 11181949 DOI: 10.1146/annurev.physiol.63.1.77] [Citation(s) in RCA: 200] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The intracellular signaling mechanisms by which cholecystokinin (CCK) and other secretagogues regulate pancreatic acinar function are more complex than originally realized. CCK couples through heterotrimeric G proteins of the Gq family to lead to an increase in intracellular free Ca2+, which shows spatial and temporal patterns of signaling. The actions of Ca2+ are mediated in part by activation of a number of Ca2+-activated protein kinases and the protein phosphatase calcineurin. By the process of exocytosis the intracellular messengers Ca2+, diacylglycerol, and cAMP activate the release of the zymogen granule content in a manner that is poorly understood. This fusion event most likely involves SNARE and Rab proteins present on zymogen granules and cellular membrane domains. More likely related to nonsecretory aspects of cell function, CCK also activates three MAPK cascades leading to activation of ERKs, JNKs, and p38 MAPK. Although the function of these pathways is not well understood, ERKs are probably related to cell growth, and through phosphorylation of hsp27, p38 can affect the actin cytoskeleton. The PI3K (phosphatidylinositol 3-kinase)-mTOR (mammalian target of rapamycin) pathway is important for regulation of acinar cell protein synthesis because it leads to both activation of p70S6K and regulation of the availability of eIF4E in response to CCK. CCK also activates a number of tyrosyl phosphorylation events including that of p125FAK and other proteins associated with focal adhesions.
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Affiliation(s)
- J A Williams
- Department of Physiology, University of Michigan, Ann Arbor, Michigan 48109-0622, USA.
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48
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Zhao XS, Shin DM, Liu LH, Shull GE, Muallem S. Plasticity and adaptation of Ca2+ signaling and Ca2+-dependent exocytosis in SERCA2(+/-) mice. EMBO J 2001; 20:2680-9. [PMID: 11387203 PMCID: PMC125253 DOI: 10.1093/emboj/20.11.2680] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Darier's disease (DD) is a high penetrance, autosomal dominant mutation in the ATP2A2 gene, which encodes the SERCA2 Ca2+ pump. Here we have used a mouse model of DD, a SERCA2(+/-) mouse, to define the adaptation of Ca2+ signaling and Ca2+-dependent exocytosis to a deletion of one copy of the SERCA2 gene. The [Ca2+]i transient evoked by maximal agonist stimulation was shorter in cells from SERCA2(+/-) mice, due to an up-regulation of specific plasma membrane Ca2+ pump isoforms. The change in cellular Ca2+ handling caused approximately 50% reduction in [Ca2+]i oscillation frequency. Nonetheless, agonist-stimulated exocytosis was identical in cells from wild-type and SERCA2(+/-) mice. This was due to adaptation in the levels of the Ca2+ sensors for exocytosis synaptotagmins I and III in cells from SERCA2(+/-) mice. Accordingly, exocytosis was approximately 10-fold more sensitive to Ca2+ in cells from SERCA2(+/-) mice. These findings reveal a remarkable plasticity and adaptability of Ca2+ signaling and Ca2+-dependent cellular functions in vivo, and can explain the normal function of most physiological systems in DD patients.
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Affiliation(s)
| | | | - Lynne H. Liu
- Department of Physiology, The University of Texas Southwestern Medical Center at Dallas, 5323 Harry Hines Boulevard, Dallas, TX 75390-9040 and
Department of Molecular Genetics, Biochemistry and Microbiology, University of Cincinnati College of Medicine, OH 45267, USA Corresponding author e-mail: X.-S.Zhao and D.M.Shin contributed equally to this work
| | - Gary E. Shull
- Department of Physiology, The University of Texas Southwestern Medical Center at Dallas, 5323 Harry Hines Boulevard, Dallas, TX 75390-9040 and
Department of Molecular Genetics, Biochemistry and Microbiology, University of Cincinnati College of Medicine, OH 45267, USA Corresponding author e-mail: X.-S.Zhao and D.M.Shin contributed equally to this work
| | - Shmuel Muallem
- Department of Physiology, The University of Texas Southwestern Medical Center at Dallas, 5323 Harry Hines Boulevard, Dallas, TX 75390-9040 and
Department of Molecular Genetics, Biochemistry and Microbiology, University of Cincinnati College of Medicine, OH 45267, USA Corresponding author e-mail: X.-S.Zhao and D.M.Shin contributed equally to this work
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González A, Schulz I, Schmid A. Agonist-evoked mitochondrial Ca2+ signals in mouse pancreatic acinar cells. J Biol Chem 2000; 275:38680-6. [PMID: 10995756 DOI: 10.1074/jbc.m005667200] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In the present study we have investigated cytosolic and mitochondrial Ca(2+) signals in isolated mouse pancreatic acinar cells double-loaded with the fluorescent probes fluo-3 and rhod-2. Stimulation of pancreatic acinar cells with 500 nm acetylcholine caused release of Ca(2+) from intracellular stores and produced cytosolic Ca(2+) signals in form of Ca(2+) waves propagating from the luminal to the basal cell pole. The increase in the cytosolic Ca(2+) concentration was followed by Ca(2+) uptake into mitochondria. Between onset of cytosolic and mitochondrial Ca(2+) signals there was a delay of 10.7 +/- 0.4 s. Ca(2+) uptake into mitochondria could be inhibited with Ruthenium Red and carbonyl cyanide m-chlorophenylhydrazone, whereas 2,5-di-tert-butylhydroquinone, which inhibits sarco(endo)plasmic reticulum Ca(2+) ATPases, did not prevent Ca(2+) accumulation in mitochondria. Carbonyl cyanide m-chlorophenylhydrazone-induced Ca(2+) release from mitochondria could only be observed after a preceding stimulation of the cell with a physiological agonist or by treatment with 2, 5-di-tert-butylhydroquinone, indicating that under resting conditions mitochondria do not contain releasable Ca(2+) ions. Analysis of the propagation rate of acetylcholine-induced Ca(2+) waves revealed that inhibition of mitochondrial Ca(2+) uptake did not accelerate spreading of cytosolic Ca(2+) signals. Our experiments indicate that in the early phase of secretagogue-induced Ca(2+) signals, mitochondria behave as passive Ca(2+)-buffering elements and do not actively suppress spreading of Ca(2+) signals in pancreatic acinar cells.
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Affiliation(s)
- A González
- Department of Physiology, University of the Saarland, D-66421 Homburg/Saar, Germany
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Park MK, Petersen OH, Tepikin AV. The endoplasmic reticulum as one continuous Ca(2+) pool: visualization of rapid Ca(2+) movements and equilibration. EMBO J 2000; 19:5729-39. [PMID: 11060024 PMCID: PMC305795 DOI: 10.1093/emboj/19.21.5729] [Citation(s) in RCA: 187] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We investigated whether the endoplasmic reticulum (ER) is a functionally connected Ca(2+) store or is composed of separate subunits by monitoring movements of Ca(2+) and small fluorescent probes in the ER lumen of pancreatic acinar cells, using confocal microscopy, local bleaching and uncaging. We observed rapid movements and equilibration of Ca(2+) and the probes. The bulk of the ER at the base was not connected to the granules in the apical part, but diffusion into small apical ER extensions occurred. The connectivity of the ER Ca(2+) store was robust, since even supramaximal acetylcholine (ACh) stimulation for 30 min did not result in functional fragmentation. ACh could elicit a uniform decrease in the ER Ca(2+) concentration throughout the cell, but repetitive cytosolic Ca(2+) spikes, induced by a low ACh concentration, hardly reduced the ER Ca(2+) level. We conclude that the ER is a functionally continuous unit, which enables efficient Ca(2+) liberation. Ca(2+) released from the apical ER terminals is quickly replenished from the bulk of the rough ER at the base.
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Affiliation(s)
- M K Park
- MRC Secretory Control Research Group, The Physiological Laboratory, University of Liverpool, Crown Street, PO Box 147, Liverpool L69 3BX, UK
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