1
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Hodeify R, Machaca K. Methods to Quantify the Dynamic Recycling of Plasma Membrane Channels. Bio Protoc 2023; 13:e4800. [PMID: 37719078 PMCID: PMC10501913 DOI: 10.21769/bioprotoc.4800] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Revised: 06/19/2023] [Accepted: 06/19/2023] [Indexed: 09/19/2023] Open
Abstract
Store-operated Ca2+ entry (SOCE) is a ubiquitous Ca2+ signaling modality mediated by Orai Ca2+ channels at the plasma membrane (PM) and the endoplasmic reticulum (ER) Ca2+ sensors STIM1/2. At steady state, Orai1 constitutively cycles between an intracellular compartment and the PM. Orai1 PM residency is modulated by its endocytosis and exocytosis rates. Therefore, Orai1 trafficking represents an important regulatory mechanism to define the levels of Ca2+ influx. Here, we present a protocol using the dually tagged YFP-HA-Orai1 with a cytosolic YFP and extracellular hemagglutinin (HA) tag to quantify Orai1 cycling rates. For measuring Orai1 endocytosis, cells expressing YFP-HA-Orai1 are incubated with mouse anti-HA antibody for various periods of time before being fixed and stained for surface Orai1 with Cy5-labeled anti-mouse IgG. The cells are fixed again, permeabilized, and stained with Cy3-labeled anti-mouse IgG to reveal anti-HA that has been internalized. To quantify Orai1 exocytosis rate, cells are incubated with anti-HA antibody for various incubation periods before being fixed, permeabilized, and then stained with Cy5-labeled anti-mouse IgG. The Cy5/YFP ratio is plotted over time and fitted with a mono-exponential growth curve to determine exocytosis rate. Although the described assays were developed to measure Orai1 trafficking, they are readily adaptable to other PM channels. Key features Detailed protocols to quantify endocytosis and exocytosis rates of Orai1 at the plasma membrane that can be used in various cell lines. The endocytosis and exocytosis assays are readily adaptable to study the trafficking of other plasma membrane channels.
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Affiliation(s)
- Rawad Hodeify
- Biotechnology Department, School of Arts and
Sciences, American University of Ras Al Khaimah, Ras Al Khaimah, United Arab
Emirates
| | - Khaled Machaca
- Ca
- Department of Physiology and Biophysics, Weill
Cornell Medicine, New York, USA
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2
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Jardin I, Alvarado S, Sanchez-Collado J, Nieto-Felipe J, Lopez JJ, Salido GM, Rosado JA. Functional differences in agonist-induced plasma membrane expression of Orai1α and Orai1β. J Cell Physiol 2023; 238:2050-2062. [PMID: 37332264 DOI: 10.1002/jcp.31055] [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: 02/08/2023] [Revised: 04/20/2023] [Accepted: 05/24/2023] [Indexed: 06/20/2023]
Abstract
Orai1 is the pore-forming subunit of the store-operated Ca2+ release-activated Ca2+ (CRAC) channels involved in a variety of cellular functions. Two Orai1 variants have been identified, the long form, Orai1α, containing 301 amino acids, and the short form, Orai1β, which arises from alternative translation initiation from methionines 64 or 71, in Orai1α. Orai1 is mostly expressed in the plasma membrane, but a subset of Orai1 is located in intracellular compartments. Here we show that Ca2+ store depletion leads to trafficking and insertion of compartmentalized Orai1α in the plasma membrane via a mechanism that is independent on changes in cytosolic free-Ca2+ concentration, as demonstrated by cell loading with the fast intracellular Ca2+ chelator dimethyl BAPTA in the absence of extracellular Ca2+ . Interestingly, thapsigargin (TG) was found to be unable to induce translocation of Orai1β to the plasma membrane when expressed individually; by contrast, when Orai1β is co-expressed with Orai1α, cell treatment with TG induced rapid trafficking and insertion of compartmentalized Orai1β in the plasma membrane. Translocation of Orai1 forms to the plasma membrane was found to require the integrity of the actin cytoskeleton. Finally, expression of a dominant negative mutant of the small GTPase ARF6, and ARF6-T27N, abolished the translocation of compartmentalized Orai1 variants to the plasma membrane upon store depletion. These findings provide new insights into the mechanism that regulate the plasma membrane abundance of Orai1 variants after Ca2+ store depletion.
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Affiliation(s)
- Isaac Jardin
- Department of Physiology (Cellular Physiology Research Group), Institute of Molecular Pathology Biomarkers (IMPB), University of Extremadura, Caceres, Spain
| | - Sandra Alvarado
- Department of Physiology (Cellular Physiology Research Group), Institute of Molecular Pathology Biomarkers (IMPB), University of Extremadura, Caceres, Spain
| | - Jose Sanchez-Collado
- Department of Physiology (Cellular Physiology Research Group), Institute of Molecular Pathology Biomarkers (IMPB), University of Extremadura, Caceres, Spain
| | - Joel Nieto-Felipe
- Department of Physiology (Cellular Physiology Research Group), Institute of Molecular Pathology Biomarkers (IMPB), University of Extremadura, Caceres, Spain
| | - Jose J Lopez
- Department of Physiology (Cellular Physiology Research Group), Institute of Molecular Pathology Biomarkers (IMPB), University of Extremadura, Caceres, Spain
| | - Gines M Salido
- Department of Physiology (Cellular Physiology Research Group), Institute of Molecular Pathology Biomarkers (IMPB), University of Extremadura, Caceres, Spain
| | - Juan A Rosado
- Department of Physiology (Cellular Physiology Research Group), Institute of Molecular Pathology Biomarkers (IMPB), University of Extremadura, Caceres, Spain
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3
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Nuanced Interactions between AKAP79 and STIM1 with Orai1 Ca 2+ Channels at Endoplasmic Reticulum-Plasma Membrane Junctions Sustain NFAT Activation. Mol Cell Biol 2022; 42:e0017522. [PMID: 36317924 PMCID: PMC9670898 DOI: 10.1128/mcb.00175-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A-kinase anchoring protein 79 (AKAP79) is a human scaffolding protein that organizes Ca2+/calmodulin-dependent protein phosphatase calcineurin, calmodulin, cAMP-dependent protein kinase, protein kinase C, and the transcription factor nuclear factor of activated T cells (NFAT1) into a signalosome at the plasma membrane. Upon Ca2+ store depletion, AKAP79 interacts with the N-terminus of STIM1-gated Orai1 Ca2+ channels, enabling Ca2+ nanodomains to stimulate calcineurin. Calcineurin then dephosphorylates and activates NFAT1, which then translocates to the nucleus. A fundamental question is how signalosomes maintain long-term signaling when key effectors are released and therefore removed beyond the reach of the activating signal. Here, we show that the AKAP79-Orai1 interaction is considerably more transient than that of STIM1-Orai1. Free AKAP79, with calcineurin and NFAT1 in tow, is able to replace rapidly AKAP79 devoid of NFAT1 on Orai1, in the presence of continuous Ca2+ entry. We also show that Ca2+ nanodomains near Orai1 channels activate almost the entire cytosolic pool of NFAT1. Recycling of inactive NFAT1 from the cytoplasm to AKAP79 in the plasma membrane, coupled with the relatively weak interaction between AKAP79 and Orai1, maintain excitation-transcription coupling. By measuring rates for AKAP79-NFAT interaction, we formulate a mathematical model that simulates NFAT dynamics at the plasma membrane.
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4
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STIM Proteins and Regulation of SOCE in ER-PM Junctions. Biomolecules 2022; 12:biom12081152. [PMID: 36009047 PMCID: PMC9405863 DOI: 10.3390/biom12081152] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Revised: 08/12/2022] [Accepted: 08/15/2022] [Indexed: 11/30/2022] Open
Abstract
ER-PM junctions are membrane contact sites formed by the endoplasmic reticulum (ER) and plasma membrane (PM) in close apposition together. The formation and stability of these junctions are dependent on constitutive and dynamic enrichment of proteins, which either contribute to junctional stability or modulate the lipid levels of both ER and plasma membranes. The ER-PM junctions have come under much scrutiny recently as they serve as hubs for assembling the Ca2+ signaling complexes. This review summarizes: (1) key findings that underlie the abilities of STIM proteins to accumulate in ER-PM junctions; (2) the modulation of Orai/STIM complexes by other components found within the same junction; and (3) how Orai1 channel activation is coordinated and coupled with downstream signaling pathways.
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5
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Hollenhorst MI, Kumar P, Zimmer M, Salah A, Maxeiner S, Elhawy MI, Evers SB, Flockerzi V, Gudermann T, Chubanov V, Boehm U, Krasteva-Christ G. Taste Receptor Activation in Tracheal Brush Cells by Denatonium Modulates ENaC Channels via Ca2+, cAMP and ACh. Cells 2022; 11:cells11152411. [PMID: 35954259 PMCID: PMC9367940 DOI: 10.3390/cells11152411] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Revised: 07/23/2022] [Accepted: 08/03/2022] [Indexed: 02/04/2023] Open
Abstract
Mucociliary clearance is a primary defence mechanism of the airways consisting of two components, ciliary beating and transepithelial ion transport (ISC). Specialised chemosensory cholinergic epithelial cells, named brush cells (BC), are involved in regulating various physiological and immunological processes. However, it remains unclear if BC influence ISC. In murine tracheae, denatonium, a taste receptor agonist, reduced basal ISC in a concentration-dependent manner (EC50 397 µM). The inhibition of bitter taste signalling components with gallein (Gβγ subunits), U73122 (phospholipase C), 2-APB (IP3-receptors) or with TPPO (Trpm5, transient receptor potential-melastatin 5 channel) reduced the denatonium effect. Supportively, the ISC was also diminished in Trpm5−/− mice. Mecamylamine (nicotinic acetylcholine receptor, nAChR, inhibitor) and amiloride (epithelial sodium channel, ENaC, antagonist) decreased the denatonium effect. Additionally, the inhibition of Gα subunits (pertussis toxin) reduced the denatonium effect, while an inhibition of phosphodiesterase (IBMX) increased and of adenylate cyclase (forskolin) reversed the denatonium effect. The cystic fibrosis transmembrane conductance regulator (CFTR) inhibitor CFTRinh172 and the KCNQ1 potassium channel antagonist chromanol 293B both reduced the denatonium effect. Thus, denatonium reduces ISC via the canonical bitter taste signalling cascade leading to the Trpm5-dependent nAChR-mediated inhibition of ENaC as well as Gα signalling leading to a reduction in cAMP-dependent ISC. Therefore, BC activation contributes to the regulation of fluid homeostasis.
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Affiliation(s)
| | - Praveen Kumar
- Institute of Anatomy and Cell Biology, Saarland University, 66421 Homburg, Germany
| | - Maxim Zimmer
- Institute of Anatomy and Cell Biology, Saarland University, 66421 Homburg, Germany
| | - Alaa Salah
- Institute of Anatomy and Cell Biology, Saarland University, 66421 Homburg, Germany
| | - Stephan Maxeiner
- Institute of Anatomy and Cell Biology, Saarland University, 66421 Homburg, Germany
| | | | - Saskia B. Evers
- Institute of Anatomy and Cell Biology, Saarland University, 66421 Homburg, Germany
| | - Veit Flockerzi
- Institute for Experimental and Clinical Pharmacology and Toxicology, Centre for Molecular Signalling, Saarland University, 66421 Homburg, Germany
| | - Thomas Gudermann
- Walter-Straub-Institute for Pharmacology and Toxicology, Ludwig-Maximilians-University and German Centre for Lung Research (DZL), 80366 Munich, Germany
| | - Vladimir Chubanov
- Walter-Straub-Institute for Pharmacology and Toxicology, Ludwig-Maximilians-University and German Centre for Lung Research (DZL), 80366 Munich, Germany
| | - Ulrich Boehm
- Experimental Pharmacology, Centre for Molecular Signalling, School of Medicine, Saarland University, 66421 Homburg, Germany
| | - Gabriela Krasteva-Christ
- Institute of Anatomy and Cell Biology, Saarland University, 66421 Homburg, Germany
- Correspondence: ; Tel.: +49-6841-16-26101
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Wu B, Woo JS, Sun Z, Srikanth S, Gwack Y. Ca 2+ Signaling Augmented by ORAI1 Trafficking Regulates the Pathogenic State of Effector T Cells. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2022; 208:1329-1340. [PMID: 35217583 PMCID: PMC8916982 DOI: 10.4049/jimmunol.2100871] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Accepted: 01/07/2022] [Indexed: 02/02/2023]
Abstract
Activation of the Ca2+ release-activated Ca2+ (CRAC) channel is crucial for T cell functions. It was recently shown that naked cuticle homolog 2 (NKD2), a signaling adaptor molecule, orchestrates trafficking of ORAI1, a pore subunit of the CRAC channels, to the plasma membrane for sustained activation of the CRAC channels. However, the physiological role of sustained Ca2+ entry via ORAI1 trafficking remains poorly understood. Using NKD2 as a molecular handle, we show that ORAI1 trafficking is crucial for sustained Ca2+ entry and cytokine production, especially in inflammatory Th1 and Th17 cells. We find that murine T cells cultured under pathogenic Th17-polarizing conditions have higher Ca2+ levels that are NKD2-dependent than those under nonpathogenic conditions. In vivo, deletion of Nkd2 alleviated clinical symptoms of experimental autoimmune encephalomyelitis in mice by selectively decreasing effector T cell responses in the CNS. Furthermore, we observed a strong correlation between NKD2 expression and proinflammatory cytokine production in effector T cells. Taken together, our findings suggest that the pathogenic effector T cell response demands sustained Ca2+ entry supported by ORAI1 trafficking.
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Affiliation(s)
- Beibei Wu
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, CA; and
| | - Jin Seok Woo
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, CA; and
| | - Zuoming Sun
- Department of Molecular Imaging and Therapy, Beckman Research Institute of City of Hope, Duarte, CA
| | - Sonal Srikanth
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, CA; and
| | - Yousang Gwack
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, CA; and
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7
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Humer C, Romanin C, Höglinger C. Highlighting the Multifaceted Role of Orai1 N-Terminal- and Loop Regions for Proper CRAC Channel Functions. Cells 2022; 11:371. [PMID: 35159181 PMCID: PMC8834118 DOI: 10.3390/cells11030371] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Revised: 01/14/2022] [Accepted: 01/15/2022] [Indexed: 11/16/2022] Open
Abstract
Orai1, the Ca2+-selective pore in the plasma membrane, is one of the key components of the Ca2+release-activated Ca2+ (CRAC) channel complex. Activated by the Ca2+ sensor in the endoplasmic reticulum (ER) membrane, stromal interaction molecule 1 (STIM1), via direct interaction when ER luminal Ca2+ levels recede, Orai1 helps to maintain Ca2+ homeostasis within a cell. It has already been proven that the C-terminus of Orai1 is indispensable for channel activation. However, there is strong evidence that for CRAC channels to function properly and maintain all typical hallmarks, such as selectivity and reversal potential, additional parts of Orai1 are needed. In this review, we focus on these sites apart from the C-terminus; namely, the second loop and N-terminus of Orai1 and on their multifaceted role in the functioning of CRAC channels.
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Affiliation(s)
| | | | - Carmen Höglinger
- Institute of Biophysics, Johannes Kepler University Linz, Gruberstrasse 40, 4020 Linz, Austria; (C.H.); (C.R.)
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8
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Carreras-Sureda A, Abrami L, Ji-Hee K, Wang WA, Henry C, Frieden M, Didier M, van der Goot FG, Demaurex N. S-acylation by ZDHHC20 targets ORAI1 channels to lipid rafts for efficient Ca 2+ signaling by Jurkat T cell receptors at the immune synapse. eLife 2021; 10:72051. [PMID: 34913437 PMCID: PMC8683079 DOI: 10.7554/elife.72051] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Accepted: 11/29/2021] [Indexed: 12/29/2022] Open
Abstract
Efficient immune responses require Ca2+ fluxes across ORAI1 channels during engagement of T cell receptors (TCR) at the immune synapse (IS) between T cells and antigen presenting cells. Here, we show that ZDHHC20-mediated S-acylation of the ORAI1 channel at residue Cys143 promotes TCR recruitment and signaling at the IS. Cys143 mutations reduced ORAI1 currents and store-operated Ca2+ entry in HEK-293 cells and nearly abrogated long-lasting Ca2+ elevations, NFATC1 translocation, and IL-2 secretion evoked by TCR engagement in Jurkat T cells. The acylation-deficient channel remained in cholesterol-poor domains upon enforced ZDHHC20 expression and was recruited less efficiently to the IS along with actin and TCR. Our results establish S-acylation as a critical regulator of ORAI1 channel trafficking and function at the IS and reveal that ORAI1 S-acylation enhances TCR recruitment to the synapse.
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Affiliation(s)
| | - Laurence Abrami
- Faculty of Life Sciences, Global Health Institute, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Kim Ji-Hee
- Department of Physiology, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea
| | - Wen-An Wang
- Department of Cell Physiology and Metabolism, Geneva, Switzerland
| | | | - Maud Frieden
- Department of Cell Physiology and Metabolism, Geneva, Switzerland
| | - Monica Didier
- Department of Cell Physiology and Metabolism, Geneva, Switzerland
| | - F Gisou van der Goot
- Faculty of Life Sciences, Global Health Institute, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Nicolas Demaurex
- Department of Cell Physiology and Metabolism, Geneva, Switzerland
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9
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Voros O, Panyi G, Hajdu P. Immune Synapse Residency of Orai1 Alters Ca 2+ Response of T Cells. Int J Mol Sci 2021; 22:ijms222111514. [PMID: 34768945 PMCID: PMC8583858 DOI: 10.3390/ijms222111514] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 10/11/2021] [Accepted: 10/18/2021] [Indexed: 12/19/2022] Open
Abstract
CRAC, which plays important role in Ca2+-dependent T-lymphocyte activation, is composed of the ER-resident STIM1 and the plasma membrane Orai1 pore-forming subunit. Both accumulate at the immunological synapse (IS) between a T cell and an antigen-presenting cell (APC). We hypothesized that adapter/interacting proteins regulate Orai1 residence in the IS. We could show that mGFP-tagged Orai1-Full channels expressed in Jurkat cells had a biphasic IS-accumulation kinetics peaked at 15 min. To understand the background of Orai1 IS-redistribution we knocked down STIM1 and SAP97 (adaptor protein with a short IS-residency (15 min) and ability to bind Orai1 N-terminus): the mGFP-Orai1-Full channels kept on accumulating in the IS up to the 60th minute in the STIM1- and SAP97-lacking Jurkat cells. Deletion of Orai1 N terminus (mGFP-Orai1-Δ72) resulted in the same time course as described for STIM1/SAP97 knock-down cells. Ca2+-imaging of IS-engaged T-cells revealed that of Orai1 residency modifies the Ca2+-response: cells expressing mGFP-Orai1-Δ72 construct or mGFP-Orai1-Full in SAP-97 knock-down cells showed higher number of Ca2+-oscillation up to the 90th minute after IS formation. Overall, these data suggest that SAP97 may contribute to the short-lived IS-residency of Orai1 and binding of STIM1 to Orai1 N-terminus is necessary for SAP97-Orai1 interaction.
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Affiliation(s)
- Orsolya Voros
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Egyetem tér 1, 4032 Debrecen, Hungary; (O.V.); (G.P.)
| | - György Panyi
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Egyetem tér 1, 4032 Debrecen, Hungary; (O.V.); (G.P.)
| | - Péter Hajdu
- Department of Biophysics and Cell Biology, Faculty of Dentistry, University of Debrecen, Nagyerdei krt. 98, 4032 Debrecen, Hungary
- Correspondence: ; Tel.: +36-52-258603
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10
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Wu B, Woo JS, Vila P, Jew M, Leung J, Sun Z, Srikanth S, Gwack Y. NKD2 mediates stimulation-dependent ORAI1 trafficking to augment Ca 2+ entry in T cells. Cell Rep 2021; 36:109603. [PMID: 34433025 PMCID: PMC8435239 DOI: 10.1016/j.celrep.2021.109603] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Revised: 06/21/2021] [Accepted: 08/03/2021] [Indexed: 01/19/2023] Open
Abstract
Sustained activation of the Ca2+-release-activated Ca2+ (CRAC) channel is pivotal for effector T cell responses. The mechanisms underlying this sustainability remain poorly understood. We find that plasma membrane localization of ORAI1, the pore subunit of CRAC channels, is limited in effector T cells, with a significant fraction trapped in intracellular vesicles. From a targeted screen, we identify an essential component of ORAI1+ vesicles, naked cuticle homolog 2 (NKD2). Mechanistically, NKD2, an adaptor molecule activated by signaling pathways downstream of T cell receptors, orchestrates trafficking and insertion of ORAI1+ vesicles to the plasma membrane. Together, our findings suggest that T cell receptor (TCR)-stimulation-dependent insertion of ORAI1 into the plasma membrane is essential for sustained Ca2+ signaling and cytokine production in T cells.
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Affiliation(s)
- Beibei Wu
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles CA 90095, USA
| | - Jin Seok Woo
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles CA 90095, USA
| | - Pamela Vila
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles CA 90095, USA,Present address: Olive View-UCLA Medical Center, 14445 Olive View Drive, Sylmar, CA 91342, USA
| | - Marcus Jew
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles CA 90095, USA,Present address: Ronald Reagan UCLA Medical Center, 757 Westwood Plaza, Los Angeles, CA 90095, USA
| | - Jennifer Leung
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles CA 90095, USA,Present address: Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA
| | - Zuoming Sun
- Department of Molecular Imaging & Therapy, Beckman Research Institute of City of Hope, Duarte, CA 91010, USA
| | - Sonal Srikanth
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles CA 90095, USA.
| | - Yousang Gwack
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles CA 90095, USA.
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11
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The store-operated Ca 2+ entry complex comprises a small cluster of STIM1 associated with one Orai1 channel. Proc Natl Acad Sci U S A 2021; 118:2010789118. [PMID: 33649206 PMCID: PMC7958290 DOI: 10.1073/pnas.2010789118] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Store-operated Ca2+ entry (SOCE) links Ca2+ release from endoplasmic reticulum (ER) to Ca2+ entry across the plasma membrane (PM). SOCE is unusual in requiring interaction between proteins in different membranes. STIM1, when it senses loss of ER Ca2+, unfurls domains that interact with Orai1 PM Ca2+ channels. The stoichiometry of the SOCE complex is contentious, but it determines the regulation and functional consequences of SOCE. We show that native complexes are likely to comprise a single Orai1 channel and a few STIM1 dimers, too few to cluster Orai1 channels. We suggest that SOCE may be digitally regulated by local ER depletion, and that local SOCE-evoked Ca2+ fluxes are small enough to allow substantial intracellular redistribution of Ca2+ through ER tunnels. Increases in cytosolic Ca2+ concentration regulate diverse cellular activities and are usually evoked by opening of Ca2+ channels in intracellular Ca2+ stores and the plasma membrane (PM). For the many signals that evoke formation of inositol 1,4,5-trisphosphate (IP3), IP3 receptors coordinate the contributions of these two Ca2+ sources by mediating Ca2+ release from the endoplasmic reticulum (ER). Loss of Ca2+ from the ER then activates store-operated Ca2+ entry (SOCE) by causing dimers of STIM1 to cluster and unfurl cytosolic domains that interact with the PM Ca2+ channel, Orai1, causing its pore to open. The relative concentrations of STIM1 and Orai1 are important, but most analyses of their interactions use overexpressed proteins that perturb the stoichiometry. We tagged endogenous STIM1 with EGFP using CRISPR/Cas9. SOCE evoked by loss of ER Ca2+ was unaffected by the tag. Step-photobleaching analysis of cells with empty Ca2+ stores revealed an average of 14.5 STIM1 molecules within each sub-PM punctum. The fluorescence intensity distributions of immunostained Orai1 puncta were minimally affected by store depletion, and similar for Orai1 colocalized with STIM1 puncta or remote from them. We conclude that each native SOCE complex is likely to include only a few STIM1 dimers associated with a single Orai1 channel. Our results, demonstrating that STIM1 does not assemble clusters of interacting Orai channels, suggest mechanisms for digital regulation of SOCE by local depletion of the ER.
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12
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Yeh YC, Lin YP, Kramer H, Parekh AB. Single-nucleotide polymorphisms in Orai1 associated with atopic dermatitis inhibit protein turnover, decrease calcium entry and disrupt calcium-dependent gene expression. Hum Mol Genet 2021; 29:1808-1823. [PMID: 31600783 PMCID: PMC7372555 DOI: 10.1093/hmg/ddz223] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Revised: 08/10/2019] [Accepted: 08/12/2019] [Indexed: 12/23/2022] Open
Abstract
Loss-of function mutations in Orai1 Ca2+ channels lead to a form of severe combined immunodeficiency, auto-immunity, muscle hypotonia and defects in dental enamel production and sweat gland function. Two single-nucleotide polymorphisms (SNPs) in Orai1 have been found and localize to the second extracellular loop. These polymorphisms associate with atopic dermatitis but how they affect Ca2+ signalling and cell function is unknown. Here, we find that Orai1–SNPs turnover considerably more slowly than wild type Orai1 and are more abundantly expressed in the plasma membrane. We show a central role for flotillin in the endocytotic recycling of Orai1 channels and that endocytosed wild type Orai1 is trafficked to Rab 7-positive late endosomes for lysosomal degradation. Orai1–SNPs escape the degradation pathway and instead enter Rab 11-positive recycling endosomes, where they are returned to the surface membrane through Arf6-dependent exocytosis. We find that Orai1–SNPs escape late endosomes through endosomal pH regulation of interaction between the channel and flotillin. We identify a pH-sensitive electrostatic interaction between positively charged arginine in extracellular loop 2 (K210) and a negatively charged aspartate (D112) in extracellular loop 1 that helps determine Orai1 turnover. The increase in membrane Orai1–SNP leads to a mis-match in Orai1–STIM stoichiometry, resulting in inhibition of Ca2+ entry and Ca2+-dependent gene expression. Our results identify new strategies for targeting atopic dermatitis.
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Affiliation(s)
- Yi-Chun Yeh
- Department of Physiology, Anatomy and Genetics, Parks Road, Oxford, OX1 3PT UK
| | - Yu-Ping Lin
- Department of Physiology, Anatomy and Genetics, Parks Road, Oxford, OX1 3PT UK
| | - Holger Kramer
- MRC London Institute of Medical Sciences, Imperial College London, UK
| | - Anant B Parekh
- Department of Physiology, Anatomy and Genetics, Parks Road, Oxford, OX1 3PT UK
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13
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Sadras F, Stewart TA, Robitaille M, Peters AA, Croft PKD, Soon PS, Saunus JM, Lakhani SR, Roberts-Thomson SJ, Monteith GR. Altered Calcium Influx Pathways in Cancer-Associated Fibroblasts. Biomedicines 2021; 9:biomedicines9060680. [PMID: 34208665 PMCID: PMC8234491 DOI: 10.3390/biomedicines9060680] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2021] [Revised: 06/10/2021] [Accepted: 06/12/2021] [Indexed: 11/16/2022] Open
Abstract
Cancer-associated fibroblasts (CAFs) represent an important component of the tumour microenvironment and are implicated in disease progression. Two outstanding questions in cancer biology are how CAFs arise and how they might be targeted therapeutically. The calcium signal also has an important role in tumorigenesis. To date, the role of calcium signalling pathways in the induction of the CAF phenotype remains unexplored. A CAF model was generated through exogenous transforming growth factor beta 1 (TGFβ1) stimulation of the normal human mammary fibroblast cell line, HMF3S (HMF3S-CAF), and changes in calcium signalling were investigated. Functional changes in HMF3S-CAF calcium signalling pathways were assessed using a fluorescent indicator, gene expression, gene-silencing and pharmacological approaches. HMF3S-CAF cells demonstrated functionally altered calcium influx pathways with reduced store-operated calcium entry. In support of a calcium signalling switch, two voltage-gated calcium channel (VGCC) family members, CaV1.2 and CaV3.2, were upregulated in HMF3S-CAFs and a subset of patient-derived breast CAFs. Both siRNA-mediated silencing and pharmacological inhibition of CaV1.2 or CaV3.2 significantly impaired CAF activation in HMF3S cells. Our findings show that VGCCs contribute to TGFβ1-mediated induction of HMF3S-CAF cells and both transcriptional interference and pharmacological antagonism of CaV1.2 and CaV3.2 inhibit CAF induction. This suggests a potential therapeutic role for targeting calcium signalling in breast CAFs.
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Affiliation(s)
- Francisco Sadras
- School of Pharmacy, The University of Queensland, Brisbane, QLD 4102, Australia; (F.S.); (M.R.); (A.A.P.); (S.J.R.-T.)
| | - Teneale A. Stewart
- Mater Research, Translational Research Institute, The University of Queensland, Brisbane, QLD 4102, Australia;
| | - Mélanie Robitaille
- School of Pharmacy, The University of Queensland, Brisbane, QLD 4102, Australia; (F.S.); (M.R.); (A.A.P.); (S.J.R.-T.)
| | - Amelia A. Peters
- School of Pharmacy, The University of Queensland, Brisbane, QLD 4102, Australia; (F.S.); (M.R.); (A.A.P.); (S.J.R.-T.)
| | - Priyakshi Kalita-de Croft
- Centre for Clinical Research, Faculty of Medicine, The University of Queensland, Herston, QLD 4006, Australia; (P.K.-d.C.); (J.M.S.); (S.R.L.)
| | - Patsy S. Soon
- South Western Sydney Clinical School, University of New South Wales, Liverpool, NSW 2170, Australia;
- Department of Surgery, Bankstown Hospital, Bankstown, NSW 2200, Australia
- Medical Oncology Group, Ingham Institute for Applied Medical Research, Liverpool, NSW 2170, Australia
| | - Jodi M. Saunus
- Centre for Clinical Research, Faculty of Medicine, The University of Queensland, Herston, QLD 4006, Australia; (P.K.-d.C.); (J.M.S.); (S.R.L.)
| | - Sunil R. Lakhani
- Centre for Clinical Research, Faculty of Medicine, The University of Queensland, Herston, QLD 4006, Australia; (P.K.-d.C.); (J.M.S.); (S.R.L.)
- Pathology Queensland, The Royal Brisbane and Women’s Hospital, Herston, QLD 4029, Australia
| | - Sarah J. Roberts-Thomson
- School of Pharmacy, The University of Queensland, Brisbane, QLD 4102, Australia; (F.S.); (M.R.); (A.A.P.); (S.J.R.-T.)
| | - Gregory R. Monteith
- School of Pharmacy, The University of Queensland, Brisbane, QLD 4102, Australia; (F.S.); (M.R.); (A.A.P.); (S.J.R.-T.)
- Mater Research, Translational Research Institute, The University of Queensland, Brisbane, QLD 4102, Australia;
- Correspondence:
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14
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Store Operated Calcium Entry in Cell Migration and Cancer Metastasis. Cells 2021; 10:cells10051246. [PMID: 34069353 PMCID: PMC8158756 DOI: 10.3390/cells10051246] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Revised: 05/12/2021] [Accepted: 05/18/2021] [Indexed: 02/07/2023] Open
Abstract
Ca2+ signaling is ubiquitous in eukaryotic cells and modulates many cellular events including cell migration. Directional cell migration requires the polarization of both signaling and structural elements. This polarization is reflected in various Ca2+ signaling pathways that impinge on cell movement. In particular, store-operated Ca2+ entry (SOCE) plays important roles in regulating cell movement at both the front and rear of migrating cells. SOCE represents a predominant Ca2+ influx pathway in non-excitable cells, which are the primary migrating cells in multicellular organisms. In this review, we summarize the role of Ca2+ signaling in cell migration with a focus on SOCE and its diverse functions in migrating cells and cancer metastasis. SOCE has been implicated in regulating focal adhesion turnover in a polarized fashion and the mechanisms involved are beginning to be elucidated. However, SOCE is also involved is other aspects of cell migration with a less well-defined mechanistic understanding. Therefore, much remains to be learned regarding the role and regulation of SOCE in migrating cells.
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15
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Hodeify R, Dib M, Alcantara-Adap E, Courjaret R, Nader N, Reyes CZ, Hammad AS, Hubrack S, Yu F, Machaca K. The carboxy terminal coiled-coil modulates Orai1 internalization during meiosis. Sci Rep 2021; 11:2290. [PMID: 33504898 PMCID: PMC7840751 DOI: 10.1038/s41598-021-82048-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Accepted: 12/30/2020] [Indexed: 12/19/2022] Open
Abstract
Regulation of Ca2+ signaling is critical for the progression of cell division, especially during meiosis to prepare the egg for fertilization. The primary Ca2+ influx pathway in oocytes is Store-Operated Ca2+ Entry (SOCE). SOCE is tightly regulated during meiosis, including internalization of the SOCE channel, Orai1. Orai1 is a four-pass membrane protein with cytosolic N- and C-termini. Orai1 internalization requires a caveolin binding motif (CBM) in the N-terminus as well as the C-terminal cytosolic domain. However, the molecular determinant for Orai1 endocytosis in the C-terminus are not known. Here we show that the Orai1 C-terminus modulates Orai1 endocytosis during meiosis through a structural motif that is based on the strength of the C-terminal intersubunit coiled coil (CC) domains. Deletion mutants show that a minimal C-terminal sequence after transmembrane domain 4 (residues 260–275) supports Orai1 internalization. We refer to this region as the C-terminus Internalization Handle (CIH). Access to CIH however is dependent on the strength of the intersubunit CC. Mutants that increase the stability of the coiled coil prevent internalization independent of specific mutation. We further used human and Xenopus Orai isoforms with different propensity to form C-terminal CC and show a strong correlation between the strength of the CC and Orai internalization. Furthermore, Orai1 internalization does not depend on clathrin, flotillin or PIP2. Collectively these results argue that Orai1 internalization requires both the N-terminal CBM and C-terminal CIH where access to CIH is controlled by the strength of intersubunit C-terminal CC.
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Affiliation(s)
- Rawad Hodeify
- Department of Physiology and Biophysics, Ca2+ signaling Group, Weill Cornell Medicine Qatar, Education City, Qatar Foundation, Doha, Qatar.,Department of Biotechnology, American University of Ras Al Khaimah, Ras al Khaimah, UAE
| | - Maya Dib
- Department of Physiology and Biophysics, Ca2+ signaling Group, Weill Cornell Medicine Qatar, Education City, Qatar Foundation, Doha, Qatar
| | - Ethel Alcantara-Adap
- Department of Physiology and Biophysics, Ca2+ signaling Group, Weill Cornell Medicine Qatar, Education City, Qatar Foundation, Doha, Qatar
| | - Raphael Courjaret
- Department of Physiology and Biophysics, Ca2+ signaling Group, Weill Cornell Medicine Qatar, Education City, Qatar Foundation, Doha, Qatar
| | - Nancy Nader
- Department of Physiology and Biophysics, Ca2+ signaling Group, Weill Cornell Medicine Qatar, Education City, Qatar Foundation, Doha, Qatar
| | - Cleo Z Reyes
- Department of Physiology and Biophysics, Ca2+ signaling Group, Weill Cornell Medicine Qatar, Education City, Qatar Foundation, Doha, Qatar.,Lehigh Valley Health Network, Allentown, PA, USA
| | - Ayat S Hammad
- College of Health and Life Sciences, Hamad Bin Khalifa University, Doha, Qatar
| | - Satanay Hubrack
- Department of Physiology and Biophysics, Ca2+ signaling Group, Weill Cornell Medicine Qatar, Education City, Qatar Foundation, Doha, Qatar.,Sidra Medicine, Doha, Qatar
| | - Fang Yu
- Department of Physiology and Biophysics, Ca2+ signaling Group, Weill Cornell Medicine Qatar, Education City, Qatar Foundation, Doha, Qatar
| | - Khaled Machaca
- Department of Physiology and Biophysics, Ca2+ signaling Group, Weill Cornell Medicine Qatar, Education City, Qatar Foundation, Doha, Qatar.
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16
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Supra-Molecular Assemblies of ORAI1 at Rest Precede Local Accumulation into Puncta after Activation. Int J Mol Sci 2021; 22:ijms22020799. [PMID: 33466866 PMCID: PMC7831003 DOI: 10.3390/ijms22020799] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 01/04/2021] [Accepted: 01/12/2021] [Indexed: 12/13/2022] Open
Abstract
The Ca2+ selective channel ORAI1 and endoplasmic reticulum (ER)-resident STIM proteins form the core of the channel complex mediating store operated Ca2+ entry (SOCE). Using liquid phase electron microscopy (LPEM), the distribution of ORAI1 proteins was examined at rest and after SOCE-activation at nanoscale resolution. The analysis of over seven hundred thousand ORAI1 positions revealed a number of ORAI1 channels had formed STIM-independent distinct supra-molecular clusters. Upon SOCE activation and in the presence of STIM proteins, a fraction of ORAI1 assembled in micron-sized two-dimensional structures, such as the known puncta at the ER plasma membrane contact zones, but also in divergent structures such as strands, and ring-like shapes. Our results thus question the hypothesis that stochastically migrating single ORAI1 channels are trapped at regions containing activated STIM, and we propose instead that supra-molecular ORAI1 clusters fulfill an amplifying function for creating dense ORAI1 accumulations upon SOCE-activation.
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17
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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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18
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Jardin I, Nieto J, Salido GM, Rosado JA. TRPC6 channel and its implications in breast cancer: an overview. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2020; 1867:118828. [PMID: 32822726 DOI: 10.1016/j.bbamcr.2020.118828] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2020] [Accepted: 08/13/2020] [Indexed: 12/11/2022]
Abstract
TRPC6 channel is widely expressed in most human tissues and participates in a number of physiological processes. TRPC6 belongs to the DAG-activated subfamily of channels, but has also been postulated as a mediator in the store-operated calcium entry pathway. The recent characterization of TRPC6 crystal structure has granted a wonderful tool to finally dissect and understand TRPC6 physiological and biophysical properties. Growing evidences have demonstrated that the pattern of expression of TRPC6 proteins is upregulated in several pathophysiological conditions, including breast cancer. However, the real role of TRPC6 in breast cancer persists still unknown. Here we present the current state of the art concerning the function and significance of TRPC6 in this disease. Future investigations should be focus in the creation and identification of compounds that specifically target the channel to ameliorate TRPC6-related diseases.
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Affiliation(s)
- Isaac Jardin
- Cellular Physiology Research Group, Department of Physiology, Institute of Molecular Pathology Biomarkers, University of Extremadura, 10003 Caceres, Spain.
| | - Joel Nieto
- Cellular Physiology Research Group, Department of Physiology, Institute of Molecular Pathology Biomarkers, University of Extremadura, 10003 Caceres, Spain
| | - Ginés M Salido
- Cellular Physiology Research Group, Department of Physiology, Institute of Molecular Pathology Biomarkers, University of Extremadura, 10003 Caceres, Spain
| | - Juan A Rosado
- Cellular Physiology Research Group, Department of Physiology, Institute of Molecular Pathology Biomarkers, University of Extremadura, 10003 Caceres, Spain
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19
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Store-Operated Calcium Channels: From Function to Structure and Back Again. Cold Spring Harb Perspect Biol 2020; 12:cshperspect.a035055. [PMID: 31570335 DOI: 10.1101/cshperspect.a035055] [Citation(s) in RCA: 80] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Store-operated calcium (Ca2+) entry (SOCE) occurs through a widely distributed family of ion channels activated by the loss of Ca2+ from the endoplasmic reticulum (ER). The best understood of these is the Ca2+ release-activated Ca2+ (CRAC) channel, which is notable for its unique activation mechanism as well as its many essential physiological functions and the diverse pathologies that result from dysregulation. In response to ER Ca2+ depletion, CRAC channels are formed through a diffusion trap mechanism at ER-plasma membrane (PM) junctions, where the ER Ca2+-sensing stromal interaction molecule (STIM) proteins bind and activate hexamers of Orai pore-forming proteins to trigger Ca2+ entry. Cell biological studies are clarifying the architecture of ER-PM junctions, their roles in Ca2+ and lipid transport, and functional interactions with cytoskeletal proteins. Molecular structures of STIM and Orai have inspired a multitude of mutagenesis and electrophysiological studies that reveal potential mechanisms for how STIM is toggled between inactive and active states, how it binds and activates Orai, and the importance of STIM-binding stoichiometry for opening the channel and establishing its signature characteristics of extremely high Ca2+ selectivity and low Ca2+ conductance.
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20
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Remodeling of ER-plasma membrane contact sites but not STIM1 phosphorylation inhibits Ca 2+ influx in mitosis. Proc Natl Acad Sci U S A 2019; 116:10392-10401. [PMID: 31064875 PMCID: PMC6535005 DOI: 10.1073/pnas.1821399116] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The mechanisms blocking Ca2+ influx in mitosis are complex and involve a decrease in stable endoplasmic reticulum (ER)–plasma membrane (PM) contact sites and degradation of the ER Ca2+ sensor stromal interaction molecule 1 (STIM1) but not its phosphorylation. This challenges the current view that STIM1 phosphorylation is essential for mitotic store-operated Ca2+ entry inhibition and sheds light on the dynamics of ER–PM contact sites and of Ca2+ influx in mitosis. Store-operated Ca2+ entry (SOCE), mediated by the endoplasmic reticulum (ER) Ca2+ sensor stromal interaction molecule 1 (STIM1) and the plasma membrane (PM) channel Orai1, is inhibited during mitosis. STIM1 phosphorylation has been suggested to mediate this inhibition, but it is unclear whether additional pathways are involved. Here, we demonstrate using various approaches, including a nonphosphorylatable STIM1 knock-in mouse, that STIM1 phosphorylation is not required for SOCE inhibition in mitosis. Rather, multiple pathways converge to inhibit Ca2+ influx in mitosis. STIM1 interacts with the cochaperone BAG3 and localizes to autophagosomes in mitosis, and STIM1 protein levels are reduced. The density of ER–PM contact sites (CSs) is also dramatically reduced in mitosis, thus physically preventing STIM1 and Orai1 from interacting to activate SOCE. Our findings provide insights into ER–PM CS remodeling during mitosis and a mechanistic explanation of the inhibition of Ca2+ influx that is required for cell cycle progression.
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21
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Jha A, Chung WY, Vachel L, Maleth J, Lake S, Zhang G, Ahuja M, Muallem S. Anoctamin 8 tethers endoplasmic reticulum and plasma membrane for assembly of Ca 2+ signaling complexes at the ER/PM compartment. EMBO J 2019; 38:embj.2018101452. [PMID: 31061173 DOI: 10.15252/embj.2018101452] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2018] [Revised: 04/03/2019] [Accepted: 04/05/2019] [Indexed: 12/18/2022] Open
Abstract
Communication and material transfer between membranes and organelles take place at membrane contact sites (MCSs). MCSs between the ER and PM, the ER/PM junctions, are the sites where the ER Ca2+ sensor STIM1 and the PM Ca2+ influx channel Orai1 cluster. MCSs are formed by tether proteins that bridge the opposing membranes, but the identity and role of these tethers in receptor-evoked Ca2+ signaling is not well understood. Here, we identified Anoctamin 8 (ANO8) as a key tether in the formation of the ER/PM junctions that is essential for STIM1-STIM1 interaction and STIM1-Orai1 interaction and channel activation at a ER/PM PI(4,5)P2-rich compartment. Moreover, ANO8 assembles all core Ca2+ signaling proteins: Orai1, PMCA, STIM1, IP3 receptors, and SERCA2 at the ER/PM junctions to mediate a novel form of Orai1 channel inactivation by markedly facilitating SERCA2-mediated Ca2+ influx into the ER. This controls the efficiency of receptor-stimulated Ca2+ signaling, Ca2+ oscillations, and duration of Orai1 activity to prevent Ca2+ toxicity. These findings reveal the central role of MCSs in determining efficiency and fidelity of cell signaling.
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Affiliation(s)
- Archana Jha
- The Epithelial Signaling and Transport Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
| | - Woo Young Chung
- The Epithelial Signaling and Transport Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
| | - Laura Vachel
- The Epithelial Signaling and Transport Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
| | - Jozsef Maleth
- First Department of Medicine, University of Szeged, Szeged, Hungary
| | - Sarah Lake
- The Epithelial Signaling and Transport Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
| | - Guofeng Zhang
- Trans-NIH Shared Resource on Biomedical Engineering and Physical Science (BEPS) National Institute of Biomedical Imaging & Bioengineering, Bethesda, MD, USA
| | - Malini Ahuja
- The Epithelial Signaling and Transport Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
| | - Shmuel Muallem
- The Epithelial Signaling and Transport Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
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22
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Pierro C, Zhang X, Kankeu C, Trebak M, Bootman MD, Roderick HL. Oncogenic KRAS suppresses store-operated Ca 2+ entry and I CRAC through ERK pathway-dependent remodelling of STIM expression in colorectal cancer cell lines. Cell Calcium 2018; 72:70-80. [PMID: 29748135 PMCID: PMC6291847 DOI: 10.1016/j.ceca.2018.03.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Revised: 03/13/2018] [Accepted: 03/13/2018] [Indexed: 12/30/2022]
Abstract
The KRAS GTPase plays a fundamental role in transducing signals from plasma membrane growth factor receptors to downstream signalling pathways controlling cell proliferation, survival and migration. Activating KRAS mutations are found in 20% of all cancers and in up to 40% of colorectal cancers, where they contribute to dysregulation of cell processes underlying oncogenic transformation. Multiple KRAS-regulated cell functions are also influenced by changes in intracellular Ca2+ levels that are concurrently modified by receptor signalling pathways. Suppression of intracellular Ca2+ release mechanisms can confer a survival advantage in cancer cells, and changes in Ca2+ entry across the plasma membrane modulate cell migration and proliferation. However, inconsistent remodelling of Ca2+ influx and its signalling role has been reported in studies of transformed cells. To isolate the interaction between altered Ca2+ handling and mutated KRAS in colorectal cancer, we have previously employed isogenic cell line pairs, differing by the presence of an oncogenic KRAS allele (encoding KRASG13D), and have shown that reduced Ca2+ release from the ER and mitochondrial Ca2+ uptake contributes to the survival advantage conferred by oncogenic KRAS. Here we show in the same cell lines, that Store-Operated Ca2+ Entry (SOCE) and its underlying current, ICRAC are under the influence of KRASG13D. Specifically, deletion of the oncogenic KRAS allele resulted in enhanced STIM1 expression and greater Ca2+ influx. Consistent with the role of KRAS in the activation of the ERK pathway, MEK inhibition in cells with KRASG13D resulted in increased STIM1 expression. Further, ectopic expression of STIM1 in HCT 116 cells (which express KRASG13D) rescued SOCE, demonstrating a fundamental role of STIM1 in suppression of Ca2+ entry downstream of KRASG13D. These results add to the understanding of how ERK controls cancer cell physiology and highlight STIM1 as an important biomarker in cancerogenesis.
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Affiliation(s)
- Cristina Pierro
- Laboratory of Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium; Previously at Babraham Institute, Babraham Research Campus, Cambridge, UK
| | - Xuexin Zhang
- Department of Cellular and Molecular Physiology and Penn State Hershey Cancer Institute, Penn State College of Medicine, Hershey PA 17033, United States
| | - Cynthia Kankeu
- Laboratory of Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium
| | - Mohamed Trebak
- Department of Cellular and Molecular Physiology and Penn State Hershey Cancer Institute, Penn State College of Medicine, Hershey PA 17033, United States
| | - Martin D Bootman
- Previously at Babraham Institute, Babraham Research Campus, Cambridge, UK; School of Life, Health and Chemical Sciences, The Open University, UK
| | - H Llewelyn Roderick
- Laboratory of Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium; Previously at Babraham Institute, Babraham Research Campus, Cambridge, UK.
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23
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Tam KC, Ali E, Hua J, Chataway T, Barritt GJ. Evidence for the interaction of peroxiredoxin-4 with the store-operated calcium channel activator STIM1 in liver cells. Cell Calcium 2018; 74:14-28. [PMID: 29804005 DOI: 10.1016/j.ceca.2018.05.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2018] [Revised: 05/04/2018] [Accepted: 05/12/2018] [Indexed: 12/22/2022]
Abstract
Ca2+ entry through store-operated Ca2+ channels (SOCs) in the plasma membrane (PM) of hepatocytes plays a central role in the hormonal regulation of liver metabolism. SOCs are composed of Orai1, the channel pore protein, and STIM1, the activator protein, and are regulated by hormones and reactive oxygen species (ROS). In addition to Orai1, STIM1 also interacts with several other intracellular proteins. Most previous studies of the cellular functions of Orai1 and STIM1 have employed immortalised cells in culture expressing ectopic proteins tagged with a fluorescent polypeptide such as GFP. Little is known about the intracellular distributions of endogenous Orai1 and STIM1. The aims are to determine the intracellular distribution of endogenous Orai1 and STIM1 in hepatocytes and to identify novel STIM1 binding proteins. Subcellular fractions of rat liver were prepared by homogenisation and differential centrifugation. Orai1 and STIM1 were identified and quantified by western blot. Orai1 was found in the PM (0.03%), heavy (44%) and light (27%) microsomal fractions, and STIM1 in the PM (0.09%), and heavy (85%) and light (13%) microsomal fractions. Immunoprecipitation of STIM1 followed by LC/MS or western blot identified peroxiredoxin-4 (Prx-4) as a potential STIM1 binding protein. Prx-4 was found principally in the heavy microsomal fraction. Knockdown of Prx-4 using siRNA, or inhibition of Prx-4 using conoidin A, did not affect Ca2+ entry through SOCs but rendered SOCs susceptible to inhibition by H2O2. It is concluded that, in hepatocytes, a considerable proportion of endogenous Orai1 and STIM1 is located in the rough ER. In the rough ER, STIM1 interacts with Prx-4, and this interaction may contribute to the regulation by ROS of STIM1 and SOCs.
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Affiliation(s)
- Ka Cheung Tam
- Discipline of Medical Biochemistry, College of Medicine and Public Health, Flinders University, Adelaide, South Australia, 5001, Australia
| | - Eunus Ali
- Discipline of Medical Biochemistry, College of Medicine and Public Health, Flinders University, Adelaide, South Australia, 5001, Australia
| | - Jin Hua
- Discipline of Medical Biochemistry, College of Medicine and Public Health, Flinders University, Adelaide, South Australia, 5001, Australia
| | - Tim Chataway
- Discipline of Medical Biochemistry, College of Medicine and Public Health, Flinders University, Adelaide, South Australia, 5001, Australia
| | - Greg J Barritt
- Discipline of Medical Biochemistry, College of Medicine and Public Health, Flinders University, Adelaide, South Australia, 5001, Australia.
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24
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Nelson HA, Roe MW. Molecular physiology and pathophysiology of stromal interaction molecules. Exp Biol Med (Maywood) 2018; 243:451-472. [PMID: 29363328 DOI: 10.1177/1535370218754524] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Ca2+ release from the endoplasmic reticulum is an important component of Ca2+ signal transduction that controls numerous physiological processes in eukaryotic cells. Release of Ca2+ from the endoplasmic reticulum is coupled to the activation of store-operated Ca2+ entry into cells. Store-operated Ca2+ entry provides Ca2+ for replenishing depleted endoplasmic reticulum Ca2+ stores and a Ca2+ signal that regulates Ca2+-dependent intracellular biochemical events. Central to connecting discharge of endoplasmic reticulum Ca2+ stores following G protein-coupled receptor activation with the induction of store-operated Ca2+ entry are stromal interaction molecules (STIM1 and STIM2). These highly homologous endoplasmic reticulum transmembrane proteins function as sensors of the Ca2+ concentration within the endoplasmic reticulum lumen and activators of Ca2+ release-activated Ca2+ channels. Emerging evidence indicates that in addition to their role in Ca2+ release-activated Ca2+ channel gating and store-operated Ca2+ entry, STIM1 and STIM2 regulate other cellular signaling events. Recent studies have shown that disruption of STIM expression and function is associated with the pathogenesis of several diseases including autoimmune disorders, cancer, cardiovascular disease, and myopathies. Here, we provide an overview of the latest developments in the molecular physiology and pathophysiology of STIM1 and STIM2. Impact statement Intracellular Ca2+ signaling is a fundamentally important regulator of cell physiology. Recent studies have revealed that Ca2+-binding stromal interaction molecules (Stim1 and Stim2) expressed in the membrane of the endoplasmic reticulum (ER) are essential components of eukaryote Ca2+ signal transduction that control the activity of ion channels and other signaling effectors present in the plasma membrane. This review summarizes the most recent information on the molecular physiology and pathophysiology of stromal interaction molecules. We anticipate that the work presented in our review will provide new insights into molecular interactions that participate in interorganelle signaling crosstalk, cell function, and the pathogenesis of human diseases.
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Affiliation(s)
- Heather A Nelson
- 1 Department of Cell and Developmental Biology, 12302 SUNY Upstate Medical University, Syracuse, NY 13210, USA
| | - Michael W Roe
- 1 Department of Cell and Developmental Biology, 12302 SUNY Upstate Medical University, Syracuse, NY 13210, USA.,2 Department of Medicine, 12302 SUNY Upstate Medical University, Syracuse, NY 13210, USA
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Zheng S, Leclerc GM, Li B, Swords RT, Barredo JC. Inhibition of the NEDD8 conjugation pathway induces calcium-dependent compensatory activation of the pro-survival MEK/ERK pathway in acute lymphoblastic leukemia. Oncotarget 2017; 9:5529-5544. [PMID: 29464016 PMCID: PMC5814156 DOI: 10.18632/oncotarget.23797] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Accepted: 12/22/2017] [Indexed: 01/22/2023] Open
Abstract
De novo and acquired drug resistance and subsequent relapse remain major challenges in acute lymphoblastic leukemia (ALL). We previously identified that pevonedistat (TAK-924, MLN4924), a first-in-class inhibitor of NEDD8 activating enzyme (NAE), elicits ER stress and has potent in vitro and in vivo efficacy against ALL. However, in pevonedistat-treated ALL cell lines, we found consistent activation of the pro-survival MEK/ERK pathway, which has been associated with relapse and poor outcome in ALL. We uncovered that inhibition of the MEK/ERK pathway in vitro and in vivo sensitized ALL cells to pevonedistat. The observed synergistic apoptotic effect appears to be mediated by inhibition of the MEK/ERK pro-survival cascade leading to de-repression of the pro-apoptotic BIM protein. Mechanistically, Ca2+ influx via the Ca2+-release-activated Ca2+ (CRAC) channel induced protein kinase C β2 (PKC-β2) was responsible for activation of the MEK/ERK pathway in pevonedistat-treated ALL cells. Sequestration of Ca2+ using BAPTA-AM or blockage of store-operated Ca2+ entry (SOCE) using BTP-2 both attenuated the compensatory activation of MEK/ERK signaling in pevonedistat-treated ALL cells. Pevonedistat significantly altered the expression of Orai1 and stromal interaction molecule 1 (STIM1), resulting in significantly decreased STIM1 protein levels relative to Orai1. Further, we identified eIF2α as an important post-transcriptional regulator of STIM1, suggesting that pevonedistat-induced eIF2α de-phosphorylation selectively down-regulates translation of STIM1 mRNA. Consequently, our data suggest that pevonedistat potentially activates SOCE and promotes Ca2+ influx leading to activation of the MEK/ERK pathway by altering the stoichiometric Orai1:STIM1 ratio and inducing ER stress in ALL cells.
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Affiliation(s)
- Shuhua Zheng
- The Sheila and David Fuente Graduate Program in Cancer Biology, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Gilles M Leclerc
- Department of Pediatrics, University of Miami Miller School of Medicine, Miami, FL, USA.,Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Bin Li
- Department of Pediatrics, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Ronan T Swords
- Department of Medicine, University of Miami Miller School of Medicine, Miami, FL, USA.,Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Julio C Barredo
- Department of Pediatrics, University of Miami Miller School of Medicine, Miami, FL, USA.,Department of Medicine, University of Miami Miller School of Medicine, Miami, FL, USA.,Department of Biochemistry and Molecular Biology, University of Miami Miller School of Medicine, Miami, FL, USA.,Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami, FL, USA
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Yazbeck P, Tauseef M, Kruse K, Amin MR, Sheikh R, Feske S, Komarova Y, Mehta D. STIM1 Phosphorylation at Y361 Recruits Orai1 to STIM1 Puncta and Induces Ca 2+ Entry. Sci Rep 2017; 7:42758. [PMID: 28218251 PMCID: PMC5316956 DOI: 10.1038/srep42758] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Accepted: 01/12/2017] [Indexed: 02/07/2023] Open
Abstract
Store-operated Ca2+ entry (SOCE) mediates the increase in intracellular calcium (Ca2+) in endothelial cells (ECs) that regulates several EC functions including tissue-fluid homeostasis. Stromal-interaction molecule 1 (STIM1), upon sensing the depletion of (Ca2+) from the endoplasmic reticulum (ER) store, organizes as puncta that trigger store-operated Ca2+ entry (SOCE) via plasmalemmal Ca2+-selective Orai1 channels. While the STIM1 and Orai1 binding interfaces have been mapped, signaling mechanisms activating STIM1 recruitment of Orai1 and STIM1-Orai1 interaction remains enigmatic. Here, we show that ER Ca2+-store depletion rapidly induces STIM1 phosphorylation at Y361 via proline-rich kinase 2 (Pyk2) in ECs. Surprisingly, the phospho-defective STIM1-Y361F mutant formed puncta but failed to recruit Orai1, thereby preventing. SOCE Furthermore, studies in mouse lungs, expression of phosphodefective STIM1-Y361F mutant in ECs prevented the increase in vascular permeability induced by the thrombin receptor, protease activated receptor 1 (PAR1). Hence, Pyk2-dependent phosphorylation of STIM1 at Y361 is a critical phospho-switch enabling recruitment of Orai1 into STIM1 puncta leading to SOCE. Therefore, Y361 in STIM1 represents a novel target for limiting SOCE-associated vascular leak.
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Affiliation(s)
- Pascal Yazbeck
- Department of Pharmacology and Center for Lung and Vascular Biology, University of Illinois College of Medicine, Chicago, IL 60612, USA
| | - Mohammad Tauseef
- Department of Pharmacology and Center for Lung and Vascular Biology, University of Illinois College of Medicine, Chicago, IL 60612, USA.,Department of Pharmaceutical Sciences, College of Pharmacy, Chicago State University, Chicago, IL 60628, USA
| | - Kevin Kruse
- Department of Pharmacology and Center for Lung and Vascular Biology, University of Illinois College of Medicine, Chicago, IL 60612, USA
| | - Md-Ruhul Amin
- Department of Pharmacology and Center for Lung and Vascular Biology, University of Illinois College of Medicine, Chicago, IL 60612, USA
| | - Rayees Sheikh
- Department of Pharmacology and Center for Lung and Vascular Biology, University of Illinois College of Medicine, Chicago, IL 60612, USA
| | - Stefan Feske
- Department of Pathology, New York University School of Medicine, New York, NY 10016, USA
| | - Yulia Komarova
- Department of Pharmacology and Center for Lung and Vascular Biology, University of Illinois College of Medicine, Chicago, IL 60612, USA
| | - Dolly Mehta
- Department of Pharmacology and Center for Lung and Vascular Biology, University of Illinois College of Medicine, Chicago, IL 60612, USA
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Leech CA, Kopp RF, Nelson HA, Nandi J, Roe MW. Stromal Interaction Molecule 1 (STIM1) Regulates ATP-sensitive Potassium ( KATP) and Store-operated Ca 2+ Channels in MIN6 β-Cells. J Biol Chem 2016; 292:2266-2277. [PMID: 28003364 DOI: 10.1074/jbc.m116.767681] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2016] [Revised: 12/12/2016] [Indexed: 01/14/2023] Open
Abstract
Stromal interaction molecule 1 (STIM1) regulates store-operated Ca2+ entry (SOCE) and other ion channels either as an endoplasmic reticulum Ca2+-sensing protein or when present in the plasma membrane. However, the role of STIM1 in insulin-secreting β-cells is unresolved. We report that lowering expression of STIM1, the gene that encodes STIM1, in insulin-secreting MIN6 β-cells with RNA interference inhibits SOCE and ATP-sensitive K+ (KATP) channel activation. The effects of STIM1 knockdown were reversed by transduction of MIN6 cells with an adenovirus gene shuttle vector that expressed human STIM1 Immunoprecipitation studies revealed that STIM1 binds to nucleotide binding fold-1 (NBF1) of the sulfonylurea receptor 1 (SUR1) subunit of the KATP channel. Binding of STIM1 to SUR1 was enhanced by poly-lysine. Our data indicate that SOCE and KATP channel activity are regulated by STIM1. This suggests that STIM1 is a multifunctional signaling effector that participates in the control of membrane excitability and Ca2+ signaling events in β-cells.
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Affiliation(s)
| | | | - Heather A Nelson
- the Department of Cell and Developmental Biology, SUNY Upstate Medical University, Syracuse, New York 13210
| | | | - Michael W Roe
- From the Department of Medicine and .,the Department of Cell and Developmental Biology, SUNY Upstate Medical University, Syracuse, New York 13210
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Peckys DB, Alansary D, Niemeyer BA, de Jonge N. Visualizing Quantum Dot Labeled ORAI1 Proteins in Intact Cells Via Correlative Light and Electron Microscopy. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2016; 22:902-912. [PMID: 27515473 DOI: 10.1017/s1431927616011491] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
ORAI1 proteins are ion channel subunits and the essential pore-forming units of the calcium release-activated calcium channel complex essential for T-cell activation and many other cellular processes. In this study, we used environmental scanning electron microscopy (ESEM) with scanning transmission electron microscopy (STEM) detection to image plasma membrane expressed ORAI1 proteins in whole Jurkat T cells in the liquid state. Utilizing a stably transfected Jurkat T cell clone expressing human ORAI1 with an extracellular human influenza hemagglutinin (HA) tag we investigated if liquid-phase STEM can be applied to detect recombinant surface expressed protein. Streptavidin coated quantum dots were coupled in a one-to-one stoichiometry to ORAI1 proteins detected by biotinylated anti-HA fragmented antibody fragments. High-resolution electron microscopic images revealed the individual label locations from which protein pair distances were determined. These data were analyzed using the pair correlation function and, in addition, an analysis of cluster size and frequency was performed. ORAI1 was found to be present in hexamers in a small fraction only, and ORAI1 resided mostly in monomers and dimers.
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Affiliation(s)
- Diana B Peckys
- 1Department of Molecular Biophysics,Saarland University,CIPMM,66421 Homburg,Germany
| | - Dalia Alansary
- 1Department of Molecular Biophysics,Saarland University,CIPMM,66421 Homburg,Germany
| | - Barbara A Niemeyer
- 1Department of Molecular Biophysics,Saarland University,CIPMM,66421 Homburg,Germany
| | - Niels de Jonge
- 2INM - Leibniz Institute for New Materials,66123 Saarbrücken,Germany
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Dörr K, Kilch T, Kappel S, Alansary D, Schwär G, Niemeyer BA, Peinelt C. Cell type-specific glycosylation of Orai1 modulates store-operated Ca2+ entry. Sci Signal 2016; 9:ra25. [PMID: 26956484 DOI: 10.1126/scisignal.aaa9913] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
N-glycosylation of cell surface proteins affects protein function, stability, and interaction with other proteins. Orai channels, which mediate store-operated Ca(2+) entry (SOCE), are composed of N-glycosylated subunits. Upon activation by Ca(2+) sensor proteins (stromal interaction molecules STIM1 or STIM2) in the endoplasmic reticulum, Orai Ca(2+) channels in the plasma membrane mediate Ca(2+) influx. Lectins are carbohydrate-binding proteins, and Siglecs are a family of sialic acid-binding lectins with immunoglobulin-like repeats. Using Western blot analysis and lectin-binding assays from various primary human cells and cancer cell lines, we found that glycosylation of Orai1 is cell type-specific. Ca(2+) imaging experiments and patch-clamp experiments revealed that mutation of the only glycosylation site of Orai1 (Orai1N223A) enhanced SOCE in Jurkat T cells. Knockdown of the sialyltransferase ST6GAL1 reduced α-2,6-linked sialic acids in the glycan structure of Orai1 and was associated with increased Ca(2+) entry in Jurkat T cells. In human mast cells, inhibition of sialyl sulfation altered the N-glycan of Orai1 (and other proteins) and increased SOCE. These data suggest that cell type-specific glycosylation influences the interaction of Orai1 with specific lectins, such as Siglecs, which then attenuates SOCE. In summary, the glycosylation state of Orai1 influences SOCE-mediated Ca(2+) signaling and, thus, may contribute to pathophysiological Ca(2+) signaling observed in immune disease and cancer.
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Affiliation(s)
- Kathrin Dörr
- Biophysics, Center for Integrative Physiology and Molecular Medicine, School of Medicine, Saarland University, Homburg 66421, Germany. Molecular Biophysics, Center for Integrative Physiology and Molecular Medicine, School of Medicine, Saarland University, Homburg 66421, Germany. Center of Human and Molecular Biology, Saarland University, Homburg 66421, Germany
| | - Tatiana Kilch
- Biophysics, Center for Integrative Physiology and Molecular Medicine, School of Medicine, Saarland University, Homburg 66421, Germany. Center of Human and Molecular Biology, Saarland University, Homburg 66421, Germany
| | - Sven Kappel
- Biophysics, Center for Integrative Physiology and Molecular Medicine, School of Medicine, Saarland University, Homburg 66421, Germany. Center of Human and Molecular Biology, Saarland University, Homburg 66421, Germany
| | - Dalia Alansary
- Molecular Biophysics, Center for Integrative Physiology and Molecular Medicine, School of Medicine, Saarland University, Homburg 66421, Germany
| | - Gertrud Schwär
- Biophysics, Center for Integrative Physiology and Molecular Medicine, School of Medicine, Saarland University, Homburg 66421, Germany. Molecular Biophysics, Center for Integrative Physiology and Molecular Medicine, School of Medicine, Saarland University, Homburg 66421, Germany
| | - Barbara A Niemeyer
- Molecular Biophysics, Center for Integrative Physiology and Molecular Medicine, School of Medicine, Saarland University, Homburg 66421, Germany
| | - Christine Peinelt
- Biophysics, Center for Integrative Physiology and Molecular Medicine, School of Medicine, Saarland University, Homburg 66421, Germany. Center of Human and Molecular Biology, Saarland University, Homburg 66421, Germany.
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30
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Niemeyer BA. Changing calcium: CRAC channel (STIM and Orai) expression, splicing, and posttranslational modifiers. Am J Physiol Cell Physiol 2016; 310:C701-9. [PMID: 26911279 DOI: 10.1152/ajpcell.00034.2016] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
A wide variety of cellular function depends on the dynamics of intracellular Ca(2+) signals. Especially for relatively slow and lasting processes such as gene expression, cell proliferation, and often migration, cells rely on the store-operated Ca(2+) entry (SOCE) pathway, which is particularly prominent in immune cells. SOCE is initiated by the sensor proteins (STIM1, STIM2) located within the endoplasmic reticulum (ER) registering the Ca(2+) concentration within the ER, and upon its depletion, cluster and trap Orai (Orai1-3) proteins located in the plasma membrane (PM) into ER-PM junctions. These regions become sites of highly selective Ca(2+) entry predominantly through Orai1-assembled channels, which, among other effector functions, is necessary for triggering NFAT translocation into the nucleus. What is less clear is how the spatial and temporal spread of intracellular Ca(2+) is shaped and regulated by differential expression of the individual SOCE genes and their splice variants, their heteromeric combinations and pre- and posttranslational modifications. This review focuses on principle mechanisms regulating expression, splicing, and targeting of Ca(2+) release-activated Ca(2+) (CRAC) channels.
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Affiliation(s)
- Barbara A Niemeyer
- Molecular Biophysics, Center for Integrative Physiology and Molecular Medicine, Saarland University, Homburg, Germany
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