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Henry C, Carreras-Sureda A, Demaurex N. Enforced tethering elongates the cortical endoplasmic reticulum and limits store-operated calcium entry. J Cell Sci 2022; 135:274483. [PMID: 35191477 PMCID: PMC8995094 DOI: 10.1242/jcs.259313] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Accepted: 02/14/2022] [Indexed: 12/03/2022] Open
Abstract
Recruitment of STIM proteins to cortical endoplasmic reticulum (cER) domains forming membrane contact sites (MCSs) mediate the store-operated Ca2+ entry (SOCE) pathway essential for human immunity. The cER is dynamically regulated by STIM and tethering proteins during SOCE, but the ultrastructural rearrangement and functional consequences of cER remodeling are unknown. Here, we express natural (E-Syt1 and E-Syt2) and artificial (MAPPER-S and MAPPER-L) protein tethers in HEK-293T cells and correlate the changes in cER length and gap distance, as measured by electron microscopy, with ionic fluxes. We found that native cER cisternae extended during store depletion and remained elongated at a constant ER-plasma membrane (PM) gap distance during subsequent Ca2+ elevations. Tethering proteins enhanced store-dependent cER expansion, anchoring the enlarged cER at tether-specific gap distances of 12-15 nm (E-Syts) and 5-9 nm (MAPPERs). Cells with artificially extended cER had reduced SOCE and reduced agonist-induced Ca2+ release. SOCE remained modulated by calmodulin and exhibited enhanced Ca2+-dependent inhibition. We propose that cER expansion mediated by ER-PM tethering at a close distance negatively regulates SOCE by confining STIM-ORAI complexes to the periphery of enlarged cER sheets, a process that might participate in the termination of store-operated Ca2+ entry. Summary: ER-PM tethering at close distance limits Ca2+ entry by confining STIM-ORAI complexes to the periphery of contact sites.
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Affiliation(s)
- Christopher Henry
- Department of Cell Physiology and Metabolism, University of Geneva, Geneva, 1211, Switzerland
| | - Amado Carreras-Sureda
- Department of Cell Physiology and Metabolism, University of Geneva, Geneva, 1211, Switzerland
| | - Nicolas Demaurex
- Department of Cell Physiology and Metabolism, University of Geneva, Geneva, 1211, Switzerland
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2
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Endoplasmic reticulum stress and unfolded protein response in cardiovascular diseases. Nat Rev Cardiol 2021; 18:499-521. [PMID: 33619348 DOI: 10.1038/s41569-021-00511-w] [Citation(s) in RCA: 312] [Impact Index Per Article: 104.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 01/11/2021] [Indexed: 02/07/2023]
Abstract
Cardiovascular diseases (CVDs), such as ischaemic heart disease, cardiomyopathy, atherosclerosis, hypertension, stroke and heart failure, are among the leading causes of morbidity and mortality worldwide. Although specific CVDs and the associated cardiometabolic abnormalities have distinct pathophysiological and clinical manifestations, they often share common traits, including disruption of proteostasis resulting in accumulation of unfolded or misfolded proteins in the endoplasmic reticulum (ER). ER proteostasis is governed by the unfolded protein response (UPR), a signalling pathway that adjusts the protein-folding capacity of the cell to sustain the cell's secretory function. When the adaptive UPR fails to preserve ER homeostasis, a maladaptive or terminal UPR is engaged, leading to the disruption of ER integrity and to apoptosis. ER stress functions as a double-edged sword, with long-term ER stress resulting in cellular defects causing disturbed cardiovascular function. In this Review, we discuss the distinct roles of the UPR and ER stress response as both causes and consequences of CVD. We also summarize the latest advances in our understanding of the importance of the UPR and ER stress in the pathogenesis of CVD and discuss potential therapeutic strategies aimed at restoring ER proteostasis in CVDs.
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3
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Klose M, Scheungrab M, Luckner M, Wanner G, Linder S. FIB-SEM-based analysis of Borrelia intracellular processing by human macrophages. J Cell Sci 2021; 134:jcs252320. [PMID: 33380490 DOI: 10.1242/jcs.252320] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Accepted: 12/15/2020] [Indexed: 01/04/2023] Open
Abstract
Borrelia burgdorferi is the causative agent of Lyme disease, a multisystemic disorder affecting primarily skin, joints and nervous system. Successful internalization and intracellular processing of borreliae by immune cells, like macrophages, is decisive for the outcome of a respective infection. Here, we use, for the first time, focused ion beam scanning electron microscopy tomography (FIB-SEM tomography) to visualize the interaction of borreliae with primary human macrophages with high resolution. We report that interaction between macrophages and the elongated and highly motile borreliae can lead to formation of membrane tunnels that extend deeper into the host cytoplasm than the actual phagosome, most probably as a result of partial extrication of captured borreliae. We also show that membrane tubulation at borreliae-containing phagosomes, a process suggested earlier as a mechanism leading to phagosome compaction but hard to visualize in live-cell imaging, is apparently a frequent phenomenon. Finally, we demonstrate that the endoplasmic reticulum (ER) forms multiple STIM1-positive contact sites with both membrane tunnels and phagosome tubulations, confirming the important role of the ER during uptake and intracellular processing of borreliae.
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Affiliation(s)
- Matthias Klose
- Institute for Medical Microbiology, Virology and Hygiene, University Medical Center Eppendorf, 20246 Hamburg, Germany
| | | | - Manja Luckner
- Biozentrum der Ludwig-Maximilians-Universität, 82152 Planegg-Martinsried, Germany
| | - Gerhard Wanner
- Biozentrum der Ludwig-Maximilians-Universität, 82152 Planegg-Martinsried, Germany
| | - Stefan Linder
- Institute for Medical Microbiology, Virology and Hygiene, University Medical Center Eppendorf, 20246 Hamburg, Germany
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4
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Berlansky S, Humer C, Sallinger M, Frischauf I. More Than Just Simple Interaction between STIM and Orai Proteins: CRAC Channel Function Enabled by a Network of Interactions with Regulatory Proteins. Int J Mol Sci 2021; 22:E471. [PMID: 33466526 PMCID: PMC7796502 DOI: 10.3390/ijms22010471] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Revised: 12/29/2020] [Accepted: 12/29/2020] [Indexed: 12/27/2022] Open
Abstract
The calcium-release-activated calcium (CRAC) channel, activated by the release of Ca2+ from the endoplasmic reticulum (ER), is critical for Ca2+ homeostasis and active signal transduction in a plethora of cell types. Spurred by the long-sought decryption of the molecular nature of the CRAC channel, considerable scientific effort has been devoted to gaining insights into functional and structural mechanisms underlying this signalling cascade. Key players in CRAC channel function are the Stromal interaction molecule 1 (STIM1) and Orai1. STIM1 proteins span through the membrane of the ER, are competent in sensing luminal Ca2+ concentration, and in turn, are responsible for relaying the signal of Ca2+ store-depletion to pore-forming Orai1 proteins in the plasma membrane. A direct interaction of STIM1 and Orai1 allows for the re-entry of Ca2+ from the extracellular space. Although much is already known about the structure, function, and interaction of STIM1 and Orai1, there is growing evidence that CRAC under physiological conditions is dependent on additional proteins to function properly. Several auxiliary proteins have been shown to regulate CRAC channel activity by means of direct interactions with STIM1 and/or Orai1, promoting or hindering Ca2+ influx in a mechanistically diverse manner. Various proteins have also been identified to exert a modulatory role on the CRAC signalling cascade although inherently lacking an affinity for both STIM1 and Orai1. Apart from ubiquitously expressed representatives, a subset of such regulatory mechanisms seems to allow for a cell-type-specific control of CRAC channel function, considering the rather restricted expression patterns of the specific proteins. Given the high functional and clinical relevance of both generic and cell-type-specific interacting networks, the following review shall provide a comprehensive summary of regulators of the multilayered CRAC channel signalling cascade. It also includes proteins expressed in a narrow spectrum of cells and tissues that are often disregarded in other reviews of similar topics.
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Affiliation(s)
| | | | | | - Irene Frischauf
- Institute of Biophysics, Johannes Kepler University, 4020 Linz, Austria; (S.B.); (C.H.); (M.S.)
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5
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Roberts RE, Vervliet T, Bultynck G, Parys JB, Hallett MB. EPIC3, a novel Ca 2+ indicator located at the cell cortex and in microridges, detects high Ca 2+ subdomains during Ca 2+ influx and phagocytosis. Cell Calcium 2020; 92:102291. [PMID: 33099169 DOI: 10.1016/j.ceca.2020.102291] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Revised: 09/11/2020] [Accepted: 09/17/2020] [Indexed: 11/15/2022]
Abstract
The construction of a low affinity Ca2+-probe that locates to the cell cortex and cell surface wrinkles, is described called. EPIC3 (ezrin-protein indicator of Ca2+). The novel probe is a fusion of CEPIA3 with ezrin, and is used in combination with a Ca2+-insensitive probe, ezrin-mCherry, both of which locate at the cell cortex. EPIC3 was used to monitor the effect of Ca2+ influx on intra-wrinkle Ca2+ in the macrophage cell line, RAW 264.7. During experimentally-induced Ca2+influx, EPIC3 reported Ca2+ concentrations at the cell cortex in the region of 30-50 μM, with peak locations towards the tips of wrinkles reaching 80 μM. These concentrations were associated with cleavage of ezrin (a substrate for the Ca2+ activated protease calpain-1) and released the C-terminal fluors. The cortical Ca2+ levels, restricted to near the site of phagocytic cup formation and pseudopodia extension during phagocytosis also reached high levels (50-80 μM) during phagocytosis. As phagocytosis was completed, hotspots of Ca2+ near the phagosome were also observed.
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Affiliation(s)
- Rhiannon E Roberts
- Neutrophil Signalling Group, Cardiff University Medical School, Cardiff, CF14 4XN, UK
| | - Tim Vervliet
- KU Leuven, Laboratory for Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine, Leuven, Belgium
| | - Geert Bultynck
- KU Leuven, Laboratory for Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine, Leuven, Belgium
| | - Jan B Parys
- KU Leuven, Laboratory for Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine, Leuven, Belgium
| | - Maurice B Hallett
- Neutrophil Signalling Group, Cardiff University Medical School, Cardiff, CF14 4XN, UK.
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6
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Westman J, Walpole GFW, Kasper L, Xue BY, Elshafee O, Hube B, Grinstein S. Lysosome Fusion Maintains Phagosome Integrity during Fungal Infection. Cell Host Microbe 2020; 28:798-812.e6. [PMID: 33022213 DOI: 10.1016/j.chom.2020.09.004] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Revised: 08/10/2020] [Accepted: 09/02/2020] [Indexed: 12/20/2022]
Abstract
Phagosomes must maintain membrane integrity to exert their microbicidal function. Some microorganisms, however, survive and grow within phagosomes. In such instances, phagosomes must expand to avoid rupture and microbial escape. We studied whether phagosomes regulate their size to preserve integrity during infection with the fungal pathogen Candida albicans. Phagosomes release calcium as C. albicans hyphae elongate, inducing lysosome recruitment and insertion, thereby increasing the phagosomal surface area. As hyphae grow, the expanding phagosome consumes the majority of free lysosomes. Simultaneously, lysosome biosynthesis is stimulated by activation of TFEB, a transcriptional regulator of lysosomal biogenesis. Preventing lysosomal insertion causes phagosomal rupture, NLRP3 inflammasome activation, IL-1β secretion and host-cell death. Whole-genome transcriptomic analysis demonstrate that stress responses elicited in C. albicans upon engulfment are reversed if phagosome expansion is prevented. Our findings reveal a mechanism whereby phagosomes maintain integrity while expanding, ensuring that growing pathogens remain entrapped within this microbicidal compartment.
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Affiliation(s)
- Johannes Westman
- Program in Cell Biology, Peter Gilgan Centre for Research and Learning, the Hospital for Sick Children, Toronto, ON M5G 0A4, Canada
| | - Glenn F W Walpole
- Program in Cell Biology, Peter Gilgan Centre for Research and Learning, the Hospital for Sick Children, Toronto, ON M5G 0A4, Canada; Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Lydia Kasper
- Department Microbial Pathogenicity Mechanisms, Hans Knoell Institute, 07745 Jena, Germany
| | - Bessie Y Xue
- Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Osama Elshafee
- Department Microbial Pathogenicity Mechanisms, Hans Knoell Institute, 07745 Jena, Germany
| | - Bernhard Hube
- Department Microbial Pathogenicity Mechanisms, Hans Knoell Institute, 07745 Jena, Germany; Institute of Microbiology, Faculty of Biological Sciences, Friedrich Schiller University, 07743 Jena, Germany
| | - Sergio Grinstein
- Program in Cell Biology, Peter Gilgan Centre for Research and Learning, the Hospital for Sick Children, Toronto, ON M5G 0A4, Canada; Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada; Keenan Research Centre of the Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, ON M5C 1N8, Canada.
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7
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Fingerhut L, Dolz G, de Buhr N. What Is the Evolutionary Fingerprint in Neutrophil Granulocytes? Int J Mol Sci 2020; 21:E4523. [PMID: 32630520 PMCID: PMC7350212 DOI: 10.3390/ijms21124523] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 06/19/2020] [Accepted: 06/23/2020] [Indexed: 01/18/2023] Open
Abstract
Over the years of evolution, thousands of different animal species have evolved. All these species require an immune system to defend themselves against invading pathogens. Nevertheless, the immune systems of different species are obviously counteracting against the same pathogen with different efficiency. Therefore, the question arises if the process that was leading to the clades of vertebrates in the animal kingdom-namely mammals, birds, amphibians, reptiles, and fish-was also leading to different functions of immune cells. One cell type of the innate immune system that is transmigrating as first line of defense in infected tissue and counteracts against pathogens is the neutrophil granulocyte. During the host-pathogen interaction they can undergo phagocytosis, apoptosis, degranulation, and form neutrophil extracellular traps (NETs). In this review, we summarize a wide spectrum of information about neutrophils in humans and animals, with a focus on vertebrates. Special attention is kept on the development, morphology, composition, and functions of these cells, but also on dysfunctions and options for cell culture or storage.
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Affiliation(s)
- Leonie Fingerhut
- Department of Physiological Chemistry, Department of Infectious Diseases, University of Veterinary Medicine Hannover, 30559 Hannover, Germany;
- Research Center for Emerging Infections and Zoonoses (RIZ), University of Veterinary Medicine Hannover, 30559 Hannover, Germany
- Clinic for Horses, University of Veterinary Medicine Hannover, 30559 Hannover, Germany
| | - Gaby Dolz
- Escuela de Medicina Veterinaria, Universidad Nacional, Heredia 40104, Costa Rica;
| | - Nicole de Buhr
- Department of Physiological Chemistry, Department of Infectious Diseases, University of Veterinary Medicine Hannover, 30559 Hannover, Germany;
- Research Center for Emerging Infections and Zoonoses (RIZ), University of Veterinary Medicine Hannover, 30559 Hannover, Germany
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8
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Zumerle S, Calì B, Munari F, Angioni R, Di Virgilio F, Molon B, Viola A. Intercellular Calcium Signaling Induced by ATP Potentiates Macrophage Phagocytosis. Cell Rep 2020; 27:1-10.e4. [PMID: 30943393 PMCID: PMC6449513 DOI: 10.1016/j.celrep.2019.03.011] [Citation(s) in RCA: 76] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2018] [Revised: 12/26/2018] [Accepted: 03/01/2019] [Indexed: 12/14/2022] Open
Abstract
Extracellular ATP is a signaling molecule exploited by the immune cells for both autocrine regulation and paracrine communication. By performing live calcium imaging experiments, we show that triggered mouse macrophages are able to propagate calcium signals to resting bystander cells by releasing ATP. ATP-based intercellular communication is mediated by P2X4 and P2X7 receptors and is a feature of pro-inflammatory macrophages. In terms of functional significance, ATP signaling is required for efficient phagocytosis of pathogen-derived molecules and apoptotic cells and may represent a target for macrophage regulation by CD39-expressing cells. These results highlight a cell-to-cell communication mechanism tuning innate immunity.
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Affiliation(s)
- Sara Zumerle
- Department of Biomedical Sciences, University of Padova, Padova, Italy; Fondazione Istituto di Ricerca Pediatrica Città della Speranza, Padova, Italy.
| | - Bianca Calì
- Department of Biomedical Sciences, University of Padova, Padova, Italy; Fondazione Istituto di Ricerca Pediatrica Città della Speranza, Padova, Italy
| | - Fabio Munari
- Department of Biomedical Sciences, University of Padova, Padova, Italy; Fondazione Istituto di Ricerca Pediatrica Città della Speranza, Padova, Italy
| | - Roberta Angioni
- Department of Biomedical Sciences, University of Padova, Padova, Italy; Fondazione Istituto di Ricerca Pediatrica Città della Speranza, Padova, Italy
| | - Francesco Di Virgilio
- Department of Morphology, Surgery and Experimental Medicine, University of Ferrara, Ferrara, Italy
| | - Barbara Molon
- Department of Biomedical Sciences, University of Padova, Padova, Italy; Veneto Institute of Molecular Medicine, Padova, Italy
| | - Antonella Viola
- Department of Biomedical Sciences, University of Padova, Padova, Italy; Fondazione Istituto di Ricerca Pediatrica Città della Speranza, Padova, Italy
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9
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Rosales C. Neutrophils at the crossroads of innate and adaptive immunity. J Leukoc Biol 2020; 108:377-396. [DOI: 10.1002/jlb.4mir0220-574rr] [Citation(s) in RCA: 89] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2019] [Revised: 02/17/2020] [Accepted: 02/26/2020] [Indexed: 12/13/2022] Open
Affiliation(s)
- Carlos Rosales
- Departamento de Inmunología Instituto de Investigaciones Biomédicas Universidad Nacional Autónoma de México Mexico City Mexico
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10
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Molecular Mechanisms of Calcium Signaling During Phagocytosis. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1246:103-128. [PMID: 32399828 DOI: 10.1007/978-3-030-40406-2_7] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Calcium (Ca2+) is a ubiquitous second messenger involved in the regulation of numerous cellular functions including vesicular trafficking, cytoskeletal rearrangements and gene transcription. Both global as well as localized Ca2+ signals occur during phagocytosis, although their functional impact on the phagocytic process has been debated. After nearly 40 years of research, a consensus may now be reached that although not strictly required, Ca2+ signals render phagocytic ingestion and phagosome maturation more efficient, and their manipulation make an attractive avenue for therapeutic interventions. In the last decade many efforts have been made to identify the channels and regulators involved in generating and shaping phagocytic Ca2+ signals. While molecules involved in store-operated calcium entry (SOCE) of the STIM and ORAI family have taken center stage, members of the canonical, melastatin, mucolipin and vanilloid transient receptor potential (TRP), as well as purinergic P2X receptor families are now recognized to play significant roles. In this chapter, we review the recent literature on research that has linked specific Ca2+-permeable channels and regulators to phagocytic function. We highlight the fact that lipid mediators are emerging as important regulators of channel gating and that phagosomal ionic homeostasis and Ca2+ release also play essential parts. We predict that improved methodologies for measuring these factors will be critical for future advances in dissecting the intricate biology of this fascinating immune process.
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11
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Wang WA, Agellon LB, Michalak M. Organellar Calcium Handling in the Cellular Reticular Network. Cold Spring Harb Perspect Biol 2019; 11:cshperspect.a038265. [PMID: 31358518 DOI: 10.1101/cshperspect.a038265] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Ca2+ is an important intracellular messenger affecting diverse cellular processes. In eukaryotic cells, Ca2+ is handled by a myriad of Ca2+-binding proteins found in organelles that are organized into the cellular reticular network (CRN). The network is comprised of the endoplasmic reticulum, Golgi apparatus, lysosomes, membranous components of the endocytic and exocytic pathways, peroxisomes, and the nuclear envelope. Membrane contact sites between the different components of the CRN enable the rapid movement of Ca2+, and communication of Ca2+ status, within the network. Ca2+-handling proteins that reside in the CRN facilitate Ca2+ sensing, buffering, and cellular signaling to coordinate the many processes that operate within the cell.
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Affiliation(s)
- Wen-An Wang
- Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2S7, Canada
| | - Luis B Agellon
- School of Human Nutrition, McGill University, Ste. Anne de Bellevue, Quebec H9X 3V9, Canada
| | - Marek Michalak
- Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2S7, Canada
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12
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Westman J, Grinstein S, Maxson ME. Revisiting the role of calcium in phagosome formation and maturation. J Leukoc Biol 2019; 106:837-851. [DOI: 10.1002/jlb.mr1118-444r] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Revised: 04/24/2019] [Accepted: 04/25/2019] [Indexed: 12/19/2022] Open
Affiliation(s)
- Johannes Westman
- Program in Cell BiologyHospital for Sick Children Toronto Ontario Canada
| | - Sergio Grinstein
- Program in Cell BiologyHospital for Sick Children Toronto Ontario Canada
- Department of BiochemistryUniversity of Toronto Toronto Ontario Canada
- Keenan Research Centre of the Li Ka Shing Knowledge InstituteSt. Michael's Hospital Toronto Ontario Canada
| | - Michelle E. Maxson
- Program in Cell BiologyHospital for Sick Children Toronto Ontario Canada
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13
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Bulla M, Gyimesi G, Kim JH, Bhardwaj R, Hediger MA, Frieden M, Demaurex N. ORAI1 channel gating and selectivity is differentially altered by natural mutations in the first or third transmembrane domain. J Physiol 2018; 597:561-582. [PMID: 30382595 PMCID: PMC6332830 DOI: 10.1113/jp277079] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Accepted: 10/31/2018] [Indexed: 12/12/2022] Open
Abstract
KEY POINTS Gain-of-function mutations in the highly selective Ca2+ channel ORAI1 cause tubular aggregate myopathy (TAM) characterized by muscular pain, weakness and cramping. TAM-associated mutations in ORAI1 first and third transmembrane domain facilitate channel opening by STIM1, causing constitutive Ca2+ influx and increasing the currents evoked by Ca2+ store depletion. Mutation V107M additionally decreases the channel selectivity for Ca2+ ions and its inhibition by acidic pH, while mutation T184M does not alter the channel sensitivity to pH or to reactive oxygen species. The ORAI blocker GSK-7975A prevents the constitutive activity of TAM-associated channels and might be used in therapy for patients suffering from TAM. ABSTRACT Skeletal muscle differentiation relies on store-operated Ca2+ entry (SOCE) mediated by STIM proteins linking the depletion of endoplasmic/sarcoplasmic reticulum Ca2+ stores to the activation of membrane Ca2+ -permeable ORAI channels. Gain-of-function mutations in STIM1 or ORAI1 isoforms cause tubular aggregate myopathy (TAM), a skeletal muscle disorder with muscular pain, weakness and cramping. Here, we characterize two overactive ORAI1 mutants from patients with TAM: V107M and T184M, located in the first and third transmembrane domain of the channel. When ectopically expressed in HEK-293T cells or human primary myoblasts, the mutated channels increased basal and store-operated Ca2+ entry. The constitutive activity of V107M, L138F, T184M and P245L mutants was prevented by low concentrations of GSK-7975A while the G98S mutant was resistant to inhibition. Electrophysiological recordings confirmed ORAI1-V107M constitutive activity and revealed larger STIM1-gated V107M- and T184M-mediated currents with conserved fast and slow Ca2+ -dependent inactivation. Mutation V107M altered the channel selectivity for Ca2+ ions and conferred resistance to acidic inhibition. Ca2+ imaging and molecular dynamics simulations showed a preserved sensitivity of T184M to the negative regulation by reactive oxygen species. Both mutants were able to mediate SOCE in Stim1-/- /Stim2-/- mouse embryonic fibroblasts expressing the binding-deficient STIM1-F394H mutant, indicating a higher sensitivity for STIM1-mediated gating, with ORAI1-T184M gain-of-function being strictly dependent on STIM1. These findings provide new insights into the permeation and regulatory properties of ORAI1 mutants that might translate into therapies against diseases with gain-of-function mutations in ORAI1.
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Affiliation(s)
- M Bulla
- Department of Cell Physiology and Metabolism, University of Geneva, Geneva, Switzerland
| | - G Gyimesi
- Institute of Biochemistry and Molecular Medicine, University of Bern, Bern, Switzerland
| | - J H Kim
- Departments of Physiology and Global Medical Science, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea.,Mitohormesis Research Center, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea
| | - R Bhardwaj
- Institute of Biochemistry and Molecular Medicine, University of Bern, Bern, Switzerland
| | - M A Hediger
- Institute of Biochemistry and Molecular Medicine, University of Bern, Bern, Switzerland
| | - M Frieden
- Department of Cell Physiology and Metabolism, University of Geneva, Geneva, Switzerland
| | - N Demaurex
- Department of Cell Physiology and Metabolism, University of Geneva, Geneva, Switzerland
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14
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Mitochondrial junctions with cellular organelles: Ca 2+ signalling perspective. Pflugers Arch 2018; 470:1181-1192. [PMID: 29982949 PMCID: PMC6060751 DOI: 10.1007/s00424-018-2179-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Revised: 06/27/2018] [Accepted: 06/29/2018] [Indexed: 01/21/2023]
Abstract
Cellular organelles form multiple junctional complexes with one another and the emerging research area dealing with such structures and their functions is undergoing explosive growth. A new research journal named “Contact” has been recently established to facilitate the development of this research field. The current consensus is to define an organellar junction by the maximal distance between the participating organelles; and the gap of 30 nm or less is considered appropriate for classifying such structures as junctions or membrane contact sites. Ideally, the organellar junction should have a functional significance, i.e. facilitate transfer of calcium, sterols, phospholipids, iron and possibly other substances between the organelles (Carrasco and Meyer in Annu Rev Biochem 80:973–1000, 2011; Csordas et al. in Trends Cell Biol 28:523–540, 2018; Phillips and Voeltz in Nat Rev Mol Cell Biol 17:69–82, 2016; Prinz in J Cell Biol 205:759–769, 2014). It is also important to note that the junction is not just a result of a random organelle collision but have active and specific formation, stabilisation and disassembly mechanisms. The nature of these mechanisms and their role in physiology/pathophysiology are the main focus of an emerging research field. In this review, we will briefly describe junctional complexes formed by cellular organelles and then focus on the junctional complexes that are formed by mitochondria with other organelles and the role of these complexes in regulating Ca2+ signalling.
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15
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Kimura M, Nishi K, Higashikawa A, Ohyama S, Sakurai K, Tazaki M, Shibukawa Y. High pH-Sensitive Store-Operated Ca 2+ Entry Mediated by Ca 2+ Release-Activated Ca 2+ Channels in Rat Odontoblasts. Front Physiol 2018; 9:443. [PMID: 29765331 PMCID: PMC5938338 DOI: 10.3389/fphys.2018.00443] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2017] [Accepted: 04/10/2018] [Indexed: 11/13/2022] Open
Abstract
Odontoblasts play a crucial role in dentin formation and sensory transduction following the application of stimuli to the dentin surface. Various exogenous and endogenous stimuli elicit an increase in the intracellular free calcium concentration ([Ca2+]i) in odontoblasts, which is mediated by Ca2+ release from intracellular Ca2+ stores and/or Ca2+ influx from the extracellular medium. In a previous study, we demonstrated that the depletion of Ca2+ stores in odontoblasts activated store-operated Ca2+ entry (SOCE), a Ca2+ influx pathway. However, the precise biophysical and pharmacological properties of SOCE in odontoblasts have remained unclear. In the present study, we examined the functional expression and pharmacological properties of Ca2+ release-activated Ca2+ (CRAC) channels that mediate SOCE and evaluated the alkali sensitivity of SOCE in rat odontoblasts. In the absence of extracellular Ca2+, treatment with thapsigargin (TG), a sarco/endoplasmic reticulum Ca2+-ATPase inhibitor, induced an increase in [Ca2+]i. After [Ca2+]i returned to near-resting levels, the subsequent application of 2.5 mM extracellular Ca2+ resulted in an increase in [Ca2+]i which is a typical of SOCE activation. Additionally, application of 2-methylthioadenosine diphosphate trisodium salt (2-MeSADP), a P2Y1,12,13 receptor agonist, or carbachol (CCh), a muscarinic cholinergic receptor agonist, in the absence of extracellular Ca2+, induced a transient increase in [Ca2+]i. The subsequent addition of extracellular Ca2+ resulted in significantly higher [Ca2+]i in 2-MeSADP- or CCh-treated odontoblasts than in untreated cells. SOCE, that is activated by addition of extracellular Ca2+ in the TG pretreated odontoblasts was then suppressed by Synta66, BTP2, or lanthanum, which are CRAC channel inhibitors. Treatment with an alkaline solution enhanced SOCE, while treatment with HC030031, a TRPA1 channel antagonist, inhibited it. The amplitude of SOCE at pH 9 in the presence of HC030031 was higher than that at pH 7.4 in the absence of HC030031. These findings indicate that CRAC channel-mediated alkali-sensitive SOCE occurs in odontoblasts. SOCE is mediated by P2Y and muscarinic-cholinergic receptors, which are activated by endogenous ligands in odontoblasts.
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Affiliation(s)
- Maki Kimura
- Department of Physiology, Tokyo Dental College, Tokyo, Japan
| | - Koichi Nishi
- Department of Removable Prosthodontics and Gerodontology, Tokyo Dental College, Tokyo, Japan
| | | | - Sadao Ohyama
- Department of Physiology, Tokyo Dental College, Tokyo, Japan.,Department of Oral Surgery, Tokyo Metropolitan Cancer and Infectious Diseases Center Komagome Hospital, Tokyo, Japan
| | - Kaoru Sakurai
- Department of Removable Prosthodontics and Gerodontology, Tokyo Dental College, Tokyo, Japan
| | - Masakazu Tazaki
- Department of Physiology, Tokyo Dental College, Tokyo, Japan
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The Role of Mitochondria in the Activation/Maintenance of SOCE: Membrane Contact Sites as Signaling Hubs Sustaining Store-Operated Ca2+ Entry. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 993:277-296. [DOI: 10.1007/978-3-319-57732-6_15] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/10/2023]
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17
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Phagocytosis: A Fundamental Process in Immunity. BIOMED RESEARCH INTERNATIONAL 2017; 2017:9042851. [PMID: 28691037 PMCID: PMC5485277 DOI: 10.1155/2017/9042851] [Citation(s) in RCA: 290] [Impact Index Per Article: 41.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Accepted: 04/18/2017] [Indexed: 01/12/2023]
Abstract
One hundred years have passed since the death of Élie Metchnikoff (1845-1916). He was the first to observe the uptake of particles by cells and realized the importance of this process for the host response to injury and infection. He also was a strong advocate of the role of phagocytosis in cellular immunity, and with this he gave us the basis for our modern understanding of inflammation and the innate and acquired immune responses. Phagocytosis is an elegant but complex process for the ingestion and elimination of pathogens, but it is also important for the elimination of apoptotic cells and hence fundamental for tissue homeostasis. Phagocytosis can be divided into four main steps: (i) recognition of the target particle, (ii) signaling to activate the internalization machinery, (iii) phagosome formation, and (iv) phagolysosome maturation. In recent years, the use of new tools of molecular biology and microscopy has provided new insights into the cellular mechanisms of phagocytosis. In this review, we present a general view of our current knowledge on phagocytosis. We emphasize novel molecular findings, particularly on phagosome formation and maturation, and discuss aspects that remain incompletely understood.
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Regulation of calcium and phosphoinositides at endoplasmic reticulum-membrane junctions. Biochem Soc Trans 2016; 44:467-73. [PMID: 27068956 DOI: 10.1042/bst20150262] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Indexed: 11/17/2022]
Abstract
Effective cellular function requires both compartmentalization of tasks in space and time, and coordination of those efforts. The endoplasmic reticulum's (ER) expansive and ramifying structure makes it ideally suited to serve as a regulatory platform for organelle-organelle communication through membrane contacts. These contact sites consist of two membranes juxtaposed at a distance less than 30 nm that mediate the exchange of lipids and ions without the need for membrane fission or fusion, a process distinct from classical vesicular transport. Membrane contact sites are positioned by organelle-specific membrane-membrane tethering proteins and contain a growing number of additional proteins that organize information transfer to shape membrane identity. Here we briefly review the role of ER-containing membrane junctions in two important cellular functions: calcium signalling and phosphoinositide processing.
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Demaurex N, Nunes P. The role of STIM and ORAI proteins in phagocytic immune cells. Am J Physiol Cell Physiol 2016; 310:C496-508. [PMID: 26764049 PMCID: PMC4824159 DOI: 10.1152/ajpcell.00360.2015] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Phagocytic cells, such as neutrophils, macrophages, and dendritic cells, migrate to sites of infection or damage and are integral to innate immunity through two main mechanisms. The first is to directly neutralize foreign agents and damaged or infected cells by secreting toxic substances or ingesting them through phagocytosis. The second is to alert the adaptive immune system through the secretion of cytokines and the presentation of the ingested materials as antigens, inducing T cell maturation into helper, cytotoxic, or regulatory phenotypes. While calcium signaling has been implicated in numerous phagocyte functions, including differentiation, maturation, migration, secretion, and phagocytosis, the molecular components that mediate these Ca(2+) signals have been elusive. The discovery of the STIM and ORAI proteins has allowed researchers to begin clarifying the mechanisms and physiological impact of store-operated Ca(2+) entry, the major pathway for generating calcium signals in innate immune cells. Here, we review evidence from cell lines and mouse models linking STIM and ORAI proteins to the control of specific innate immune functions of neutrophils, macrophages, and dendritic cells.
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Affiliation(s)
- Nicolas Demaurex
- Department of Cell Physiology and Metabolism, University of Geneva, Geneva, Switzerland
| | - Paula Nunes
- Department of Cell Physiology and Metabolism, University of Geneva, Geneva, Switzerland
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