51
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Carvalho EJ, Stathopulos PB, Madesh M. Regulation of Ca 2+ exchanges and signaling in mitochondria. CURRENT OPINION IN PHYSIOLOGY 2020; 17:197-206. [PMID: 33103015 DOI: 10.1016/j.cophys.2020.08.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Mitochondrial calcium (mCa2+) homeostasis also plays a key role in the buffering of cytosolic calcium (cCa2+) and calcium transported into the mitochondrial matrix regulates cellular metabolism, migration and cell fate decisions. Recent work has highlighted the importance of mCa2+ homeostasis in regulating cellular function. The discovery of the mCa2+ uptake complex has shed new light on the role of mCa2+ dynamics in cytoskeletal remodeling, mitochondrial shape and motility in cellular dynamics. Here we attempt to decipher the vast landscape of calcium regulatory effects of the mitochondria, the underlying mechanisms and the dynamics that control cellular function.
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Affiliation(s)
- Edmund J Carvalho
- Department of Medicine, Centre for Precision Medicine, University of Texas Health San Antonio, San Antonio, TX, 78228.,Department of Microbiology, Centre for Cellular Immunotherapies, University of Pennsylvania, Pennsylvania, 19104
| | - Peter B Stathopulos
- Department of Physiology and Pharmacology, Western University, London, ON N6A 5C1, Canada
| | - Muniswamy Madesh
- Department of Medicine, Centre for Precision Medicine, University of Texas Health San Antonio, San Antonio, TX, 78228
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52
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Baraniak JH, Zhou Y, Nwokonko RM, Gill DL. The Intricate Coupling Between STIM Proteins and Orai Channels. CURRENT OPINION IN PHYSIOLOGY 2020; 17:106-114. [PMID: 32954113 DOI: 10.1016/j.cophys.2020.07.018] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Store-operated Ca2+ entry signals are critical for cellular regulation. This intricate signaling pathway involves coupling of proteins in two different membranes: the ER-resident Ca2+-sensing STIM proteins and the highly Ca2+-selective PM Orai channels. The molecular nature of the STIM-Orai coupling interface in ER-PM junctions and consequent Orai channel gating, are processes under intense study. We describe recent developments in determining the mechanism of Orai activation through the key STIM-Orai Activating Region (SOAR) of STIM1. We describe the unexpected unimolecular coupling of STIM with Orai and explain the observed variable stoichiometry of STIM-Orai interactions. We also define the discrete C-terminal regions in Orai channels that initially latch onto STIM proteins and mediate allosteric activation of the channel. A critical "nexus" region closely associated with the STIM-activated C-terminus of Orai1, propagates the STIM-binding signal through the four tightly-associated transmembrane helices of Orai1, finally to modify the pore-forming helices and effect channel opening.
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Affiliation(s)
- James H Baraniak
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, PA 17033
| | - Yandong Zhou
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, PA 17033
| | - Robert M Nwokonko
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, PA 17033
| | - Donald L Gill
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, PA 17033
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53
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Zhang D. Interplay between endoplasmic reticulum membrane contacts and actomyosin cytoskeleton. Cytoskeleton (Hoboken) 2020; 77:241-248. [PMID: 32543125 DOI: 10.1002/cm.21623] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 06/11/2020] [Accepted: 06/11/2020] [Indexed: 12/13/2022]
Abstract
Eukaryotic membrane-bound organelles, exhibiting distinctive morphologies, dynamics and functions, are interconnected at membrane contact sites (MCSs) through numerous tethering machineries. MCSs are required for many fundamental cellular processes, such as non-vesicular lipid transfer, calcium transport and organelle homeostasis. Actin cytoskeleton and myosin motors are known to dynamically interact with different membrane boundaries, facilitating organelle movements and partitioning. Intriguingly, recent studies have pinpointed a special participation of actomyosin at various MCSs involving the endoplasmic reticulum (ER), the most extensive membranous organelle in the cell. Here, I summarize emerging roles of ER MCSs in modulating actomyosin structures and discuss feedback functions of such actomyosin regulation at these MCSs.
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Affiliation(s)
- Dan Zhang
- Temasek Life Sciences Laboratory, 1 Research Link, National University of Singapore, Singapore, Singapore.,Department of Biological Sciences, National University of Singapore, Singapore, Singapore
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54
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Novello MJ, Zhu J, Zhang M, Feng Q, Stathopulos PB. Synergistic stabilization by nitrosoglutathione-induced thiol modifications in the stromal interaction molecule-2 luminal domain suppresses basal and store operated calcium entry. Sci Rep 2020; 10:10177. [PMID: 32576932 PMCID: PMC7311479 DOI: 10.1038/s41598-020-66961-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Accepted: 06/01/2020] [Indexed: 11/25/2022] Open
Abstract
Stromal interaction molecule−1 and −2 (STIM1/2) are endoplasmic reticulum (ER) membrane-inserted calcium (Ca2+) sensing proteins that, together with Orai1-composed Ca2+ channels on the plasma membrane (PM), regulate intracellular Ca2+ levels. Recent evidence suggests that S-nitrosylation of the luminal STIM1 Cys residues inhibits store operated Ca2+ entry (SOCE). However, the effects of thiol modifications on STIM2 during nitrosative stress and their role in regulating basal Ca2+ levels remain unknown. Here, we demonstrate that the nitric oxide (NO) donor nitrosoglutathione (GSNO) thermodynamically stabilizes the STIM2 Ca2+ sensing region in a Cys-specific manner. We uncovered a remarkable synergism in this stabilization involving the three luminal Cys of STIM2, which is unique to this paralog. S-Nitrosylation causes structural perturbations that converge on the face of the EF-hand and sterile α motif (EF-SAM) domain, implicated in unfolding-coupled activation. In HEK293T cells, enhanced free basal cytosolic Ca2+ and SOCE mediated by STIM2 overexpression could be attenuated by GSNO or mutation of the modifiable Cys located in the luminal domain. Collectively, we identify the Cys residues within the N-terminal region of STIM2 as modifiable targets during nitrosative stress that can profoundly and cooperatively affect basal Ca2+ and SOCE regulation.
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Affiliation(s)
- Matthew J Novello
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, the University of Western Ontario, London, Ontario, N6A5C1, Canada
| | - Jinhui Zhu
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, the University of Western Ontario, London, Ontario, N6A5C1, Canada.,Dentistry, Schulich School of Medicine and Dentistry, the University of Western Ontario, London, Ontario, N6A5C1, Canada
| | - MengQi Zhang
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, the University of Western Ontario, London, Ontario, N6A5C1, Canada.,Faculty of Medicine, University of Ottawa, Ottawa, Ontario, K1H8M5, Canada
| | - Qingping Feng
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, the University of Western Ontario, London, Ontario, N6A5C1, Canada.
| | - Peter B Stathopulos
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, the University of Western Ontario, London, Ontario, N6A5C1, Canada.
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55
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Noble M, Lin QT, Sirko C, Houpt JA, Novello MJ, Stathopulos PB. Structural Mechanisms of Store-Operated and Mitochondrial Calcium Regulation: Initiation Points for Drug Discovery. Int J Mol Sci 2020; 21:E3642. [PMID: 32455637 PMCID: PMC7279490 DOI: 10.3390/ijms21103642] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Revised: 05/11/2020] [Accepted: 05/17/2020] [Indexed: 12/18/2022] Open
Abstract
Calcium (Ca2+) is a universal signaling ion that is essential for the life and death processes of all eukaryotes. In humans, numerous cell stimulation pathways lead to the mobilization of sarco/endoplasmic reticulum (S/ER) stored Ca2+, resulting in the propagation of Ca2+ signals through the activation of processes, such as store-operated Ca2+ entry (SOCE). SOCE provides a sustained Ca2+ entry into the cytosol; moreover, the uptake of SOCE-mediated Ca2+ by mitochondria can shape cytosolic Ca2+ signals, function as a feedback signal for the SOCE molecular machinery, and drive numerous mitochondrial processes, including adenosine triphosphate (ATP) production and distinct cell death pathways. In recent years, tremendous progress has been made in identifying the proteins mediating these signaling pathways and elucidating molecular structures, invaluable for understanding the underlying mechanisms of function. Nevertheless, there remains a disconnect between using this accumulating protein structural knowledge and the design of new research tools and therapies. In this review, we provide an overview of the Ca2+ signaling pathways that are involved in mediating S/ER stored Ca2+ release, SOCE, and mitochondrial Ca2+ uptake, as well as pinpoint multiple levels of crosstalk between these pathways. Further, we highlight the significant protein structures elucidated in recent years controlling these Ca2+ signaling pathways. Finally, we describe a simple strategy that aimed at applying the protein structural data to initiating drug design.
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Affiliation(s)
- Megan Noble
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON N6A5C1, Canada; (M.N.); (Q.-T.L.); (C.S.); (M.J.N.)
| | - Qi-Tong Lin
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON N6A5C1, Canada; (M.N.); (Q.-T.L.); (C.S.); (M.J.N.)
| | - Christian Sirko
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON N6A5C1, Canada; (M.N.); (Q.-T.L.); (C.S.); (M.J.N.)
| | - Jacob A. Houpt
- Department of Medicine, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON N6A5C1, Canada;
| | - Matthew J. Novello
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON N6A5C1, Canada; (M.N.); (Q.-T.L.); (C.S.); (M.J.N.)
| | - Peter B. Stathopulos
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON N6A5C1, Canada; (M.N.); (Q.-T.L.); (C.S.); (M.J.N.)
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56
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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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57
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Segin S, Berlin M, Richter C, Medert R, Flockerzi V, Worley P, Freichel M, Camacho Londoño JE. Cardiomyocyte-Specific Deletion of Orai1 Reveals Its Protective Role in Angiotensin-II-Induced Pathological Cardiac Remodeling. Cells 2020; 9:cells9051092. [PMID: 32354146 PMCID: PMC7290784 DOI: 10.3390/cells9051092] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 04/22/2020] [Accepted: 04/24/2020] [Indexed: 12/11/2022] Open
Abstract
Pathological cardiac remodeling correlates with chronic neurohumoral stimulation and abnormal Ca2+ signaling in cardiomyocytes. Store-operated calcium entry (SOCE) has been described in adult and neonatal murine cardiomyocytes, and Orai1 proteins act as crucial ion-conducting constituents of this calcium entry pathway that can be engaged not only by passive Ca2+ store depletion but also by neurohumoral stimuli such as angiotensin-II. In this study, we, therefore, analyzed the consequences of Orai1 deletion for cardiomyocyte hypertrophy in neonatal and adult cardiomyocytes as well as for other features of pathological cardiac remodeling including cardiac contractile function in vivo. Cellular hypertrophy induced by angiotensin-II in embryonic cardiomyocytes from Orai1-deficient mice was blunted in comparison to cells from litter-matched control mice. Due to lethality of mice with ubiquitous Orai1 deficiency and to selectively analyze the role of Orai1 in adult cardiomyocytes, we generated a cardiomyocyte-specific and temporally inducible Orai1 knockout mouse line (Orai1CM–KO). Analysis of cardiac contractility by pressure-volume loops under basal conditions and of cardiac histology did not reveal differences between Orai1CM–KO mice and controls. Moreover, deletion of Orai1 in cardiomyocytes in adult mice did not protect them from angiotensin-II-induced cardiac remodeling, but cardiomyocyte cross-sectional area and cardiac fibrosis were enhanced. These alterations in the absence of Orai1 go along with blunted angiotensin-II-induced upregulation of the expression of Myoz2 and a lack of rise in angiotensin-II-induced STIM1 and Orai3 expression. In contrast to embryonic cardiomyocytes, where Orai1 contributes to the development of cellular hypertrophy, the results obtained from deletion of Orai1 in the adult myocardium reveal a protective function of Orai1 against the development of angiotensin-II-induced cardiac remodeling, possibly involving signaling via Orai3/STIM1-calcineurin-NFAT related pathways.
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Affiliation(s)
- Sebastian Segin
- Pharmakologisches Institut, Ruprecht-Karls-Universität Heidelberg, INF 366, 69120 Heidelberg, Germany; (S.S.); (M.B.); (C.R.); (R.M.); (M.F.)
- DZHK (German Centre for Cardiovascular Research), Partner Site Heidelberg/Mannheim, 69120 Heidelberg, Germany
| | - Michael Berlin
- Pharmakologisches Institut, Ruprecht-Karls-Universität Heidelberg, INF 366, 69120 Heidelberg, Germany; (S.S.); (M.B.); (C.R.); (R.M.); (M.F.)
- DZHK (German Centre for Cardiovascular Research), Partner Site Heidelberg/Mannheim, 69120 Heidelberg, Germany
| | - Christin Richter
- Pharmakologisches Institut, Ruprecht-Karls-Universität Heidelberg, INF 366, 69120 Heidelberg, Germany; (S.S.); (M.B.); (C.R.); (R.M.); (M.F.)
| | - Rebekka Medert
- Pharmakologisches Institut, Ruprecht-Karls-Universität Heidelberg, INF 366, 69120 Heidelberg, Germany; (S.S.); (M.B.); (C.R.); (R.M.); (M.F.)
- DZHK (German Centre for Cardiovascular Research), Partner Site Heidelberg/Mannheim, 69120 Heidelberg, Germany
| | - Veit Flockerzi
- Experimentelle und Klinische Pharmakologie und Toxikologie, Universität des Saarlandes, 66421 Homburg, Germany;
| | - Paul Worley
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, School of Medicine, Baltimore, MD 21205, USA;
| | - Marc Freichel
- Pharmakologisches Institut, Ruprecht-Karls-Universität Heidelberg, INF 366, 69120 Heidelberg, Germany; (S.S.); (M.B.); (C.R.); (R.M.); (M.F.)
- DZHK (German Centre for Cardiovascular Research), Partner Site Heidelberg/Mannheim, 69120 Heidelberg, Germany
| | - Juan E. Camacho Londoño
- Pharmakologisches Institut, Ruprecht-Karls-Universität Heidelberg, INF 366, 69120 Heidelberg, Germany; (S.S.); (M.B.); (C.R.); (R.M.); (M.F.)
- DZHK (German Centre for Cardiovascular Research), Partner Site Heidelberg/Mannheim, 69120 Heidelberg, Germany
- Correspondence: ; Tel.: +49-6221-54-86863; Fax: +49-6221-54-8644
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58
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Schartner V, Laporte J, Böhm J. Abnormal Excitation-Contraction Coupling and Calcium Homeostasis in Myopathies and Cardiomyopathies. J Neuromuscul Dis 2020; 6:289-305. [PMID: 31356215 DOI: 10.3233/jnd-180314] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Muscle contraction requires specialized membrane structures with precise geometry and relies on the concerted interplay of electrical stimulation and Ca2+ release, known as excitation-contraction coupling (ECC). The membrane structure hosting ECC is called triad in skeletal muscle and dyad in cardiac muscle, and structural or functional defects of triads and dyads have been observed in a variety of myopathies and cardiomyopathies. Based on their function, the proteins localized at the triad/dyad can be classified into three molecular pathways: the Ca2+ release complex (CRC), store-operated Ca2+ entry (SOCE), and membrane remodeling. All three are mechanistically linked, and consequently, aberrations in any of these pathways cause similar disease entities. This review provides an overview of the clinical and genetic spectrum of triad and dyad defects with a main focus of attention on the underlying pathomechanisms.
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Affiliation(s)
- Vanessa Schartner
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Illkirch, France.,INSERM U1258, Illkirch, France.,CNRS UMR7104, Illkirch, France.,Strasbourg University, Illkirch, France
| | - Jocelyn Laporte
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Illkirch, France.,INSERM U1258, Illkirch, France.,CNRS UMR7104, Illkirch, France.,Strasbourg University, Illkirch, France
| | - Johann Böhm
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Illkirch, France.,INSERM U1258, Illkirch, France.,CNRS UMR7104, Illkirch, France.,Strasbourg University, Illkirch, France
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59
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Angiotensin-II-Evoked Ca 2+ Entry in Murine Cardiac Fibroblasts Does Not Depend on TRPC Channels. Cells 2020; 9:cells9020322. [PMID: 32013125 PMCID: PMC7072683 DOI: 10.3390/cells9020322] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Revised: 01/23/2020] [Accepted: 01/25/2020] [Indexed: 02/06/2023] Open
Abstract
TRPC proteins form cation conducting channels regulated by different stimuli and are regulators of the cellular calcium homeostasis. TRPC are expressed in cardiac cells including cardiac fibroblasts (CFs) and have been implicated in the development of pathological cardiac remodeling including fibrosis. Using Ca2+ imaging and several compound TRPC knockout mouse lines we analyzed the involvement of TRPC proteins for the angiotensin II (AngII)-induced changes in Ca2+ homeostasis in CFs isolated from adult mice. Using qPCR we detected transcripts of all Trpc genes in CFs; Trpc1, Trpc3 and Trpc4 being the most abundant ones. We show that the AngII-induced Ca2+ entry but also Ca2+ release from intracellular stores are critically dependent on the density of CFs in culture and are inversely correlated with the expression of the myofibroblast marker α-smooth muscle actin. Our Ca2+ measurements depict that the AngII- and thrombin-induced Ca2+ transients, and the AngII-induced Ca2+ entry and Ca2+ release are not affected in CFs isolated from mice lacking all seven TRPC proteins (TRPC-hepta KO) compared to control cells. However, pre-incubation with GSK7975A (10 µM), which sufficiently inhibits CRAC channels in other cells, abolished AngII-induced Ca2+ entry. Consequently, we conclude the dispensability of the TRPC channels for the acute neurohumoral Ca2+ signaling evoked by AngII in isolated CFs and suggest the contribution of members of the Orai channel family as molecular constituents responsible for this pathophysiologically important Ca2+ entry pathway.
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60
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Coordination of a Single Calcium Ion in the EF-hand Maintains the Off State of the Stromal Interaction Molecule Luminal Domain. J Mol Biol 2020; 432:367-383. [DOI: 10.1016/j.jmb.2019.10.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2019] [Revised: 09/17/2019] [Accepted: 10/07/2019] [Indexed: 12/12/2022]
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61
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Popugaeva E, Bezprozvanny I, Chernyuk D. Reversal of Calcium Dysregulation as Potential Approach for Treating Alzheimer's Disease. Curr Alzheimer Res 2020; 17:344-354. [PMID: 32469698 PMCID: PMC8210816 DOI: 10.2174/1567205017666200528162046] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Revised: 02/25/2020] [Accepted: 05/11/2020] [Indexed: 02/07/2023]
Abstract
Despite decades of research and effort, there is still no effective disease-modifying treatment for Alzheimer's Disease (AD). Most of the recent AD clinical trials were targeting amyloid pathway, but all these trials failed. Although amyloid pathology is a hallmark and defining feature of AD, targeting the amyloid pathway has been very challenging due to low efficacy and serious side effects. Alternative approaches or mechanisms for our understanding of the major cause of memory loss in AD need to be considered as potential therapeutic targets. Increasing studies suggest that Ca2+ dysregulation in AD plays an important role in AD pathology and is associated with other AD abnormalities, such as excessive inflammation, increased ROS, impaired autophagy, neurodegeneration, synapse, and cognitive dysfunction. Ca2+ dysregulation in cytosolic space, Endoplasmic Reticulum (ER) and mitochondria have been reported in the context of various AD models. Drugs or strategies, to correct the Ca2+ dysregulation in AD, have been demonstrated to be promising as an approach for the treatment of AD in preclinical models. This review will discuss the mechanisms of Ca2+ dysregulation in AD and associated pathology and discuss potential approaches or strategies to develop novel drugs for the treatment of AD by targeting Ca2+ dysregulation.
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Affiliation(s)
- Elena Popugaeva
- Department of Medical Physics, Laboratory of Molecular Neurodegeneration, Peter the Great St Petersburg Polytechnic University, St Petersburg, Russia
| | - Ilya Bezprozvanny
- Department of Physiology, UT Southwestern Medical Center, Dallas, USA
| | - Daria Chernyuk
- Department of Medical Physics, Laboratory of Molecular Neurodegeneration, Peter the Great St Petersburg Polytechnic University, St Petersburg, Russia
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62
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Butorac C, Krizova A, Derler I. Review: Structure and Activation Mechanisms of CRAC Channels. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1131:547-604. [PMID: 31646526 DOI: 10.1007/978-3-030-12457-1_23] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Ca2+ release activated Ca2+ (CRAC) channels represent a primary pathway for Ca2+ to enter non-excitable cells. The two key players in this process are the stromal interaction molecule (STIM), a Ca2+ sensor embedded in the membrane of the endoplasmic reticulum, and Orai, a highly Ca2+ selective ion channel located in the plasma membrane. Upon depletion of the internal Ca2+ stores, STIM is activated, oligomerizes, couples to and activates Orai. This review provides an overview of novel findings about the CRAC channel activation mechanisms, structure and gating. In addition, it highlights, among diverse STIM and Orai mutants, also the disease-related mutants and their implications.
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Affiliation(s)
- Carmen Butorac
- Institute of Biophysics, Johannes Kepler University of Linz, Linz, Austria
| | - Adéla Krizova
- Institute of Biophysics, Johannes Kepler University of Linz, Linz, Austria
| | - Isabella Derler
- Institute of Biophysics, Johannes Kepler University of Linz, Linz, Austria.
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63
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Lopez JJ, Jardin I, Albarrán L, Sanchez-Collado J, Cantonero C, Salido GM, Smani T, Rosado JA. Molecular Basis and Regulation of Store-Operated Calcium Entry. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1131:445-469. [PMID: 31646520 DOI: 10.1007/978-3-030-12457-1_17] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Store-operated Ca2+ entry (SOCE) is a ubiquitous mechanism for Ca2+ influx in mammalian cells with important physiological implications. Since the discovery of SOCE more than three decades ago, the mechanism that communicates the information about the amount of Ca2+ accumulated in the intracellular Ca2+ stores to the plasma membrane channels and the nature of these channels have been matters of intense investigation and debate. The stromal interaction molecule-1 (STIM1) has been identified as the Ca2+ sensor of the intracellular Ca2+ compartments that activates the store-operated channels. STIM1 regulates two types of store-dependent channels: the Ca2+ release-activated Ca2+ (CRAC) channels, formed by Orai1 subunits, that conduct the highly Ca2+ selective current I CRAC and the cation permeable store-operated Ca2+ (SOC) channels, which consist of Orai1 and TRPC1 proteins and conduct the non-selective current I SOC. While the crystal structure of Drosophila CRAC channel has already been solved, the architecture of the SOC channels still remains unclear. The dynamic interaction of STIM1 with the store-operated channels is modulated by a number of proteins that either support the formation of the functional STIM1-channel complex or protect the cell against Ca2+ overload.
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Affiliation(s)
- Jose J Lopez
- Department of Physiology, Cell Physiology Research Group and Institute of Molecular Pathology Biomarkers, University of Extremadura, Cáceres, Spain
| | - Isaac Jardin
- Department of Physiology, Cell Physiology Research Group and Institute of Molecular Pathology Biomarkers, University of Extremadura, Cáceres, Spain.
| | - Letizia Albarrán
- Department of Physiology, Cell Physiology Research Group and Institute of Molecular Pathology Biomarkers, University of Extremadura, Cáceres, Spain
| | - Jose Sanchez-Collado
- Department of Physiology, Cell Physiology Research Group and Institute of Molecular Pathology Biomarkers, University of Extremadura, Cáceres, Spain
| | - Carlos Cantonero
- Department of Physiology, Cell Physiology Research Group and Institute of Molecular Pathology Biomarkers, University of Extremadura, Cáceres, Spain
| | - Gines M Salido
- Department of Physiology, Cell Physiology Research Group and Institute of Molecular Pathology Biomarkers, University of Extremadura, Cáceres, Spain
| | - Tarik Smani
- Department of Medical Physiology and Biophysics and Group of Cardiovascular Pathophysiology, Institute of Biomedicine of Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/University of Sevilla, Sevilla, Spain
| | - Juan A Rosado
- Department of Physiology, Cell Physiology Research Group and Institute of Molecular Pathology Biomarkers, University of Extremadura, Cáceres, Spain
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64
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Nelson ME, Parker BL, Burchfield JG, Hoffman NJ, Needham EJ, Cooke KC, Naim T, Sylow L, Ling NXY, Francis D, Norris DM, Chaudhuri R, Oakhill JS, Richter EA, Lynch GS, Stöckli J, James DE. Phosphoproteomics reveals conserved exercise-stimulated signaling and AMPK regulation of store-operated calcium entry. EMBO J 2019; 38:e102578. [PMID: 31381180 PMCID: PMC6912027 DOI: 10.15252/embj.2019102578] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Revised: 06/27/2019] [Accepted: 07/01/2019] [Indexed: 12/20/2022] Open
Abstract
Exercise stimulates cellular and physiological adaptations that are associated with widespread health benefits. To uncover conserved protein phosphorylation events underlying this adaptive response, we performed mass spectrometry-based phosphoproteomic analyses of skeletal muscle from two widely used rodent models: treadmill running in mice and in situ muscle contraction in rats. We overlaid these phosphoproteomic signatures with cycling in humans to identify common cross-species phosphosite responses, as well as unique model-specific regulation. We identified > 22,000 phosphosites, revealing orthologous protein phosphorylation and overlapping signaling pathways regulated by exercise. This included two conserved phosphosites on stromal interaction molecule 1 (STIM1), which we validate as AMPK substrates. Furthermore, we demonstrate that AMPK-mediated phosphorylation of STIM1 negatively regulates store-operated calcium entry, and this is beneficial for exercise in Drosophila. This integrated cross-species resource of exercise-regulated signaling in human, mouse, and rat skeletal muscle has uncovered conserved networks and unraveled crosstalk between AMPK and intracellular calcium flux.
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Affiliation(s)
- Marin E Nelson
- Charles Perkins CentreSchool of Life and Environmental SciencesSydney Medical SchoolThe University of SydneySydneyNSWAustralia
| | - Benjamin L Parker
- Charles Perkins CentreSchool of Life and Environmental SciencesSydney Medical SchoolThe University of SydneySydneyNSWAustralia
- Present address:
Department of PhysiologyThe University of MelbourneMelbourneVic.Australia
| | - James G Burchfield
- Charles Perkins CentreSchool of Life and Environmental SciencesSydney Medical SchoolThe University of SydneySydneyNSWAustralia
| | - Nolan J Hoffman
- Charles Perkins CentreSchool of Life and Environmental SciencesSydney Medical SchoolThe University of SydneySydneyNSWAustralia
- Present address:
Exercise and Nutrition Research ProgramMary MacKillop Institute for Health ResearchAustralian Catholic UniversityMelbourneVic.Australia
| | - Elise J Needham
- Charles Perkins CentreSchool of Life and Environmental SciencesSydney Medical SchoolThe University of SydneySydneyNSWAustralia
| | - Kristen C Cooke
- Charles Perkins CentreSchool of Life and Environmental SciencesSydney Medical SchoolThe University of SydneySydneyNSWAustralia
| | - Timur Naim
- Centre for Muscle ResearchDepartment of PhysiologySchool of Biomedical SciencesThe University of MelbourneMelbourneVicAustralia
| | - Lykke Sylow
- Department of Nutrition, Exercise and SportsFaculty of ScienceThe University of CopenhagenCopenhagenDenmark
| | - Naomi XY Ling
- Metabolic Signalling LaboratorySt. Vincent's Institute of Medical ResearchMelbourneVic.Australia
| | - Deanne Francis
- Charles Perkins CentreSchool of Life and Environmental SciencesSydney Medical SchoolThe University of SydneySydneyNSWAustralia
| | - Dougall M Norris
- Charles Perkins CentreSchool of Life and Environmental SciencesSydney Medical SchoolThe University of SydneySydneyNSWAustralia
| | - Rima Chaudhuri
- Charles Perkins CentreSchool of Life and Environmental SciencesSydney Medical SchoolThe University of SydneySydneyNSWAustralia
| | - Jonathan S Oakhill
- Metabolic Signalling LaboratorySt. Vincent's Institute of Medical ResearchMelbourneVic.Australia
- Exercise and Nutrition Research ProgramMary MacKillop Institute for Health ResearchAustralian Catholic UniversityMelbourneVic.Australia
| | - Erik A Richter
- Department of Nutrition, Exercise and SportsFaculty of ScienceThe University of CopenhagenCopenhagenDenmark
| | - Gordon S Lynch
- Centre for Muscle ResearchDepartment of PhysiologySchool of Biomedical SciencesThe University of MelbourneMelbourneVicAustralia
| | - Jacqueline Stöckli
- Charles Perkins CentreSchool of Life and Environmental SciencesSydney Medical SchoolThe University of SydneySydneyNSWAustralia
| | - David E James
- Charles Perkins CentreSchool of Life and Environmental SciencesSydney Medical SchoolThe University of SydneySydneyNSWAustralia
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65
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A muscular hypotonia-associated STIM1 mutant at R429 induces abnormalities in intracellular Ca 2+ movement and extracellular Ca 2+ entry in skeletal muscle. Sci Rep 2019; 9:19140. [PMID: 31844136 PMCID: PMC6915709 DOI: 10.1038/s41598-019-55745-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Accepted: 12/02/2019] [Indexed: 12/20/2022] Open
Abstract
Stromal interaction molecule 1 (STIM1) mediates extracellular Ca2+ entry into the cytosol through a store-operated Ca2+ entry (SOCE) mechanism, which is involved in the physiological functions of various tissues, including skeletal muscle. STIM1 is also associated with skeletal muscle diseases, but its pathological mechanisms have not been well addressed. The present study focused on examining the pathological mechanism(s) of a mutant STIM1 (R429C) that causes human muscular hypotonia. R429C was expressed in mouse primary skeletal myotubes, and the properties of the skeletal myotubes were examined using single-cell Ca2+ imaging of myotubes and transmission electron microscopy (TEM) along with biochemical approaches. R429C did not interfere with the terminal differentiation of myoblasts to myotubes. Unlike wild-type STIM1, there was no further increase of SOCE by R429C. R429C bound to endogenous STIM1 and slowed down the initial rate of SOCE that were mediated by endogenous STIM1. Moreover, R429C increased intracellular Ca2+ movement in response to membrane depolarization by eliminating the attenuation on dihydropyridine receptor-ryanodine receptor (DHPR-RyR1) coupling by endogenous STIM1. The cytosolic Ca2+ level was also increased due to the reduction in SR Ca2+ level. In addition, R429C-expressing myotubes showed abnormalities in mitochondrial shape, a significant decrease in ATP levels, and the higher expression levels of mitochondrial fission-mediating proteins. Therefore, serial defects in SOCE, intracellular Ca2+ movement, and cytosolic Ca2+ level along with mitochondrial abnormalities in shape and ATP level could be a pathological mechanism of R429C for human skeletal muscular hypotonia. This study also suggests a novel clue that STIM1 in skeletal muscle could be related to mitochondria via regulating intra and extracellular Ca2+ movements.
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66
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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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67
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Schober R, Bonhenry D, Lunz V, Zhu J, Krizova A, Frischauf I, Fahrner M, Zhang M, Waldherr L, Schmidt T, Derler I, Stathopulos PB, Romanin C, Ettrich RH, Schindl R. Sequential activation of STIM1 links Ca 2+ with luminal domain unfolding. Sci Signal 2019; 12:eaax3194. [PMID: 31744929 DOI: 10.1126/scisignal.aax3194] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The stromal interaction molecule 1 (STIM1) has two important functions, Ca2+ sensing within the endoplasmic reticulum and activation of the store-operated Ca2+ channel Orai1, enabling plasma-membrane Ca2+ influx. We combined molecular dynamics (MD) simulations with live-cell recordings and determined the sequential Ca2+-dependent conformations of the luminal STIM1 domain upon activation. Furthermore, we identified the residues within the canonical and noncanonical EF-hand domains that can bind to multiple Ca2+ ions. In MD simulations, a single Ca2+ ion was sufficient to stabilize the luminal STIM1 complex. Ca2+ store depletion destabilized the two EF hands, triggering disassembly of the hydrophobic cleft that they form together with the stable SAM domain. Point mutations associated with tubular aggregate myopathy or cancer that targeted the canonical EF hand, and the hydrophobic cleft yielded constitutively clustered STIM1, which was associated with activation of Ca2+ entry through Orai1 channels. On the basis of our results, we present a model of STIM1 Ca2+ binding and refine the currently known initial steps of STIM1 activation on a molecular level.
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Affiliation(s)
- Romana Schober
- Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, A-4020 Linz, Austria
| | - Daniel Bonhenry
- Center for Nanobiology and Structural Biology, Institute of Microbiology, Academy of Sciences of the Czech Republic, Nove Hrady CZ-373 33, Czech Republic
| | - Victoria Lunz
- Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, A-4020 Linz, Austria
| | - Jinhui Zhu
- Schulich Dentistry, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario N6A 5C1, Canada
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Adela Krizova
- Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, A-4020 Linz, Austria
| | - Irene Frischauf
- Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, A-4020 Linz, Austria
| | - Marc Fahrner
- Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, A-4020 Linz, Austria
| | - MengQi Zhang
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario N6A 5C1, Canada
- Faculty of Medicine, University of Ottawa, Ottawa, Ontario K1H 8M5, Canada
| | - Linda Waldherr
- Gottfried Schatz Research Center, Medical University of Graz, A-8010 Graz, Austria
| | - Tony Schmidt
- Gottfried Schatz Research Center, Medical University of Graz, A-8010 Graz, Austria
| | - Isabella Derler
- Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, A-4020 Linz, Austria
| | - Peter B Stathopulos
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Christoph Romanin
- Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, A-4020 Linz, Austria
| | - Rüdiger H Ettrich
- Center for Nanobiology and Structural Biology, Institute of Microbiology, Academy of Sciences of the Czech Republic, Nove Hrady CZ-373 33, Czech Republic.
- College of Biomedical Sciences, Larkin University, Miami, FL 33169, USA
| | - Rainer Schindl
- Gottfried Schatz Research Center, Medical University of Graz, A-8010 Graz, Austria.
- BioTechMed-Graz, A-8010 Graz, Austria
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68
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Morin G, Biancalana V, Echaniz-Laguna A, Noury JB, Lornage X, Moggio M, Ripolone M, Violano R, Marcorelles P, Maréchal D, Renaud F, Maurage CA, Tard C, Cuisset JM, Laporte J, Böhm J. Tubular aggregate myopathy and Stormorken syndrome: Mutation spectrum and genotype/phenotype correlation. Hum Mutat 2019; 41:17-37. [PMID: 31448844 DOI: 10.1002/humu.23899] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Revised: 07/29/2019] [Accepted: 08/21/2019] [Indexed: 11/06/2022]
Abstract
Calcium (Ca2+ ) acts as a ubiquitous second messenger, and normal cell and tissue physiology strictly depends on the precise regulation of Ca2+ entry, storage, and release. Store-operated Ca2+ entry (SOCE) is a major mechanism controlling extracellular Ca2+ entry, and mainly relies on the accurate interplay between the Ca2+ sensor STIM1 and the Ca2+ channel ORAI1. Mutations in STIM1 or ORAI1 result in abnormal Ca2+ homeostasis and are associated with severe human disorders. Recessive loss-of-function mutations impair SOCE and cause combined immunodeficiency, while dominant gain-of-function mutations induce excessive extracellular Ca2+ entry and cause tubular aggregate myopathy (TAM) and Stormorken syndrome (STRMK). TAM and STRMK are spectra of the same multisystemic disease characterized by muscle weakness, miosis, thrombocytopenia, hyposplenism, ichthyosis, dyslexia, and short stature. To date, 42 TAM/STRMK families have been described, and here we report five additional families for which we provide clinical, histological, ultrastructural, and genetic data. In this study, we list and review all new and previously reported STIM1 and ORAI1 cases, discuss the pathomechanisms of the mutations based on the known functions and the protein structure of STIM1 and ORAI1, draw a genotype/phenotype correlation, and delineate an efficient screening strategy for the molecular diagnosis of TAM/STRMK.
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Affiliation(s)
- Gilles Morin
- Clinical Genetics, Amiens University Hospital, Amiens, France.,University of Picardy Jules Verne, EA 4666, Amiens, France.,Department of translational medicine and Neurogenetics, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Illkirch, France
| | - Valérie Biancalana
- Department of translational medicine and Neurogenetics, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Illkirch, France.,Inserm U1258, Illkirch, France.,CNRS UMR7104, Illkirch, France.,Strasbourg University, Illkirch, France.,Laboratoire Diagnostic Génétique, CHRU, Strasbourg, France
| | - Andoni Echaniz-Laguna
- Department of Neurology, APHP, CHU de Bicêtre, Le Kremlin Bicêtre, France.,French National Reference Center for Rare Neuropathies (NNERF), Le Kremlin Bicêtre, France.,Inserm U1195 & Paris-Sud University, Le Kremlin Bicêtre, France
| | | | - Xavière Lornage
- Department of translational medicine and Neurogenetics, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Illkirch, France.,Inserm U1258, Illkirch, France.,CNRS UMR7104, Illkirch, France.,Strasbourg University, Illkirch, France
| | - Maurizio Moggio
- Neuromuscular and Rare Diseases Unit, Department of Neuroscience, Fondazione IRCCS Ca' Granda, Ospedale Maggiore Policlinico, Milan, Italy
| | - Michela Ripolone
- Neuromuscular and Rare Diseases Unit, Department of Neuroscience, Fondazione IRCCS Ca' Granda, Ospedale Maggiore Policlinico, Milan, Italy
| | - Raffaella Violano
- Neuromuscular and Rare Diseases Unit, Department of Neuroscience, Fondazione IRCCS Ca' Granda, Ospedale Maggiore Policlinico, Milan, Italy
| | | | - Denis Maréchal
- Department of Neurology, CHRU Cavale Blanche, Brest, France
| | - Florence Renaud
- Department of Pathology, Lille University Hospital, Lille, France
| | | | - Céline Tard
- CHU Lille, Inserm U1171, Service de neurologie, Centre de Référence des Maladies Neuromusculaires Nord Est Ile-de-France, Lille University, Lille, France
| | | | - Jocelyn Laporte
- Department of translational medicine and Neurogenetics, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Illkirch, France.,Inserm U1258, Illkirch, France.,CNRS UMR7104, Illkirch, France.,Strasbourg University, Illkirch, France
| | - Johann Böhm
- Department of translational medicine and Neurogenetics, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Illkirch, France.,Inserm U1258, Illkirch, France.,CNRS UMR7104, Illkirch, France.,Strasbourg University, Illkirch, France
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69
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Chen CH, Di YQ, Shen QY, Wang JX, Zhao XF. The steroid hormone 20-hydroxyecdysone induces phosphorylation and aggregation of stromal interacting molecule 1 for store-operated calcium entry. J Biol Chem 2019; 294:14922-14936. [PMID: 31413111 DOI: 10.1074/jbc.ra119.008484] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2019] [Revised: 07/29/2019] [Indexed: 12/22/2022] Open
Abstract
Oligomerization of stromal interacting molecule 1 (STIM1) promotes store-operated calcium entry (SOCE); however, the mechanism of STIM1 aggregation is unclear. Here, using the lepidopteran insect and agricultural pest cotton bollworm (Helicoverpa armigera) as a model and immunoblotting, RT-qPCR, RNA interference (RNAi), and ChIP assays, we found that the steroid hormone 20-hydroxyecdysone (20E) up-regulates STIM1 expression via G protein-coupled receptors (GPCRs) and the 20E nuclear receptor (EcRB1). We also identified an ecdysone-response element (EcRE) in the 5'-upstream region of the STIM1 gene and also noted that STIM1 is located in the larval midgut during metamorphosis. STIM1 knockdown in larvae delayed pupation time, prevented midgut remodeling, and decreased 20E-induced gene transcription. STIM1 knockdown in a H. armigera epidermal cell line, HaEpi, repressed 20E-induced calcium ion influx and apoptosis. Moreover, 20E-induced STIM1 clustering to puncta and translocation toward the cell membrane. Inhibitors of GPCRs, phospholipase C (PLC), and inositol trisphosphate receptor (IP3R) repressed 20E-induced STIM1 phosphorylation, and we found that two GPCRs are involved in 20E-induced STIM1 phosphorylation. 20E-induced STIM1 phosphorylation on Ser-485 through protein kinase C (PKC), and we observed that Ser-485 phosphorylation is critical for STIM1 clustering, interaction with calcium release-activated calcium channel modulator 1 (Orai1), calcium ion influx, and 20E-induced apoptosis. These results suggest that 20E up-regulates STIM1 phosphorylation for aggregation via GPCRs, followed by interaction with Orai1 to induce SOCE, thereby promoting apoptosis in the midgut during insect metamorphosis.
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Affiliation(s)
- Cai-Hua Chen
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Sciences, Shandong University, Qingdao 266237, China.,Department of Entomology, College of Plant Protection, Northwest A & F University, Yangling 712100, China
| | - Yu-Qin Di
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Sciences, Shandong University, Qingdao 266237, China
| | - Qin-Yong Shen
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Sciences, Shandong University, Qingdao 266237, China
| | - Jin-Xing Wang
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Sciences, Shandong University, Qingdao 266237, China
| | - Xiao-Fan Zhao
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Sciences, Shandong University, Qingdao 266237, China
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70
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Gudlur A, Zeraik AE, Hirve N, Hogan PG. STIM calcium sensing and conformational change. J Physiol 2019; 598:1695-1705. [PMID: 31228261 DOI: 10.1113/jp276524] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Accepted: 05/15/2019] [Indexed: 11/08/2022] Open
Abstract
The control of calcium influx at the plasma membrane by endoplasmic reticulum (ER) calcium stores, a process common to invertebrates and vertebrates, is central to physiological calcium signalling and cellular calcium balance. Stromal interaction molecule 1 (STIM1) is a calcium sensor and regulatory protein localized to the ER. ORAI1 is a calcium channel in the plasma membrane (PM). In outline, STIM1 senses an ER-luminal calcium decrease, relocalizes to ER-PM junctions, and recruits and gates ORAI1 channels. Recent work, reviewed here, has offered detailed insight into the process of sensing and communicating ER calcium-store depletion, and particularly into the STIM1 conformational change that is the basis for communication between the ER and the PM.
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Affiliation(s)
- Aparna Gudlur
- Division of Signaling and Gene Expression, La Jolla Institute for Immunology, La Jolla, CA, 92037, USA
| | - Ana Eliza Zeraik
- Division of Signaling and Gene Expression, La Jolla Institute for Immunology, La Jolla, CA, 92037, USA.,Instituto de Física de São Carlos, Universidade de São Paulo, São Carlos, SP, Brasil
| | - Nupura Hirve
- Division of Signaling and Gene Expression, La Jolla Institute for Immunology, La Jolla, CA, 92037, USA
| | - Patrick G Hogan
- Division of Signaling and Gene Expression, La Jolla Institute for Immunology, La Jolla, CA, 92037, USA.,Program in Immunology, University of California-San Diego, La Jolla, CA, 92037, USA.,Moores Cancer Center, University of California-San Diego, La Jolla, CA, 92093, USA
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71
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Krizova A, Maltan L, Derler I. Critical parameters maintaining authentic CRAC channel hallmarks. EUROPEAN BIOPHYSICS JOURNAL : EBJ 2019; 48:425-445. [PMID: 30903264 PMCID: PMC6647248 DOI: 10.1007/s00249-019-01355-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Revised: 12/20/2018] [Accepted: 03/06/2019] [Indexed: 12/20/2022]
Abstract
Ca2+ ions represent versatile second messengers that regulate a huge diversity of processes throughout the cell's life. One prominent Ca2+ entry pathway into the cell is the Ca2+ release-activated Ca2+ (CRAC) ion channel. It is fully reconstituted by the two molecular key players: the stromal interaction molecule (STIM1) and Orai. STIM1 is a Ca2+ sensor located in the membrane of the endoplasmic reticulum, and Orai, a highly Ca2+ selective ion channel embedded in the plasma membrane. Ca2+ store-depletion leads initially to the activation of STIM1 which subsequently activates Orai channels via direct binding. Authentic CRAC channel hallmarks and biophysical characteristics include high Ca2+ selectivity with a reversal potential in the range of + 50 mV, small unitary conductance, fast Ca2+-dependent inactivation and enhancements in currents upon the switch from a Na+-containing divalent-free to a Ca2+-containing solution. This review provides an overview on the critical determinants and structures within the STIM1 and Orai proteins that establish these prominent CRAC channel characteristics.
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Affiliation(s)
- Adéla Krizova
- Institute of Biophysics, Johannes Kepler University of Linz, Gruberstrasse 40, 4020, Linz, Austria
| | - Lena Maltan
- Institute of Biophysics, Johannes Kepler University of Linz, Gruberstrasse 40, 4020, Linz, Austria
| | - Isabella Derler
- Institute of Biophysics, Johannes Kepler University of Linz, Gruberstrasse 40, 4020, Linz, Austria.
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72
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Groenendyk J, Fan X, Peng Z, Kurgan L, Michalak M. Endoplasmic reticulum and the microRNA environment in the cardiovascular system 1. Can J Physiol Pharmacol 2019; 97:515-527. [PMID: 31063413 DOI: 10.1139/cjpp-2018-0720] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Stress responses are important to human physiology and pathology, and the inability to adapt to cellular stress leads to cell death. To mitigate cellular stress and re-establish homeostasis, cells, including those in the cardiovascular system, activate stress coping response mechanisms. The endoplasmic reticulum, a component of the cellular reticular network in cardiac cells, mobilizes so-called endoplasmic reticulum stress coping responses, such as the unfolded protein response. MicroRNAs play an important part in the maintenance of cellular and tissue homeostasis, perform a central role in the biology of the cardiac myocyte, and are involved in pathological cardiac function and remodeling. In this paper, we review a link between endoplasmic reticulum homeostasis and microRNA with an emphasis on the impact on stress responses in the cardiovascular system.
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Affiliation(s)
- Jody Groenendyk
- a Department of Biochemistry, University of Alberta, Edmonton, AB T6G 2S7, Canada
| | - Xiao Fan
- b Irving Medical Center, Columbia University, New York, NY 10032, USA
| | - Zhenling Peng
- c Center for Applied Mathematics, Tianjin University, Tianjin 300072, China
| | - Lukasz Kurgan
- d Department of Computer Science, Virginia Commonwealth University, Richmond, VA 23284, USA.,e Department of Electrical and Computer Engineering, University of Alberta, Edmonton, AB T6G 2V4, Canada
| | - Marek Michalak
- a Department of Biochemistry, University of Alberta, Edmonton, AB T6G 2S7, Canada
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73
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Li A, Kang X, Edelman F, Waclawik AJ. Stormorken Syndrome: A Rare Cause of Myopathy With Tubular Aggregates and Dystrophic Features. J Child Neurol 2019; 34:321-324. [PMID: 30761937 DOI: 10.1177/0883073819829389] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Stormorken syndrome is a rare genetic disorder (MIM 185070) first reported in 1983 with thrombocytopenia, muscle weakness, asplenia, and miosis caused by a mutation of the stromal interaction molecule 1 ( STIM1) gene.1 The muscle weakness is caused by a myopathy with tubular aggregate formation. We report a family in which both child and mother presented with proximal muscle weakness and thrombocytopenia. Histologic, histochemical, and electron microscopy studies were performed on the muscle specimen. It documented accumulation of tubular aggregates and chronic myopathic changes with dystrophic features. Genetic testing revealed that both mother and son carried a missense mutation of c.326A>G in exon 3 of the STIM1 gene, which is novel for Stormorken syndrome. We suggest that patients with unexplained chronic idiopathic thrombocytopenia and proximal weakness have genetic testing for Stormorken syndrome.
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Affiliation(s)
- Ang Li
- 1 Department of Neurology, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
| | - Xuan Kang
- 1 Department of Neurology, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
| | - Frederick Edelman
- 1 Department of Neurology, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
| | - Andrew J Waclawik
- 1 Department of Neurology, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
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74
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Hirve N, Rajanikanth V, Hogan PG, Gudlur A. Coiled-Coil Formation Conveys a STIM1 Signal from ER Lumen to Cytoplasm. Cell Rep 2019; 22:72-83. [PMID: 29298434 DOI: 10.1016/j.celrep.2017.12.030] [Citation(s) in RCA: 59] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Revised: 11/07/2017] [Accepted: 12/10/2017] [Indexed: 10/18/2022] Open
Abstract
STIM1 and STIM2 are endoplasmic reticulum (ER) membrane proteins that sense decreases in ER-luminal free Ca2+ and, through a conformational change in the STIM cytoplasmic domain, control gating of the plasma membrane Ca2+ channel ORAI1. To determine how STIM1 conveys a signal from the ER lumen to the cytoplasm, we studied the Ca2+-dependent conformational change of engineered STIM1 proteins in isolated ER membranes and, in parallel, physiological activation of these proteins in cells. We find that conserved "sentinel" features of the CC1 region help to prevent activation while Ca2+ is bound to STIM ER-luminal domains. Reduced ER-luminal Ca2+ drives a concerted conformational change, in which STIM luminal domains rearrange and the STIM transmembrane helices and initial parts of the CC1 regions pair in an extended coiled coil. This intradimer rearrangement overcomes the relatively weak CC1-SOAR/CAD interactions that hold STIM in an inactive conformation, releasing the SOAR/CAD domain to activate ORAI channels.
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Affiliation(s)
- Nupura Hirve
- Division of Signaling and Gene Expression, La Jolla Institute for Allergy and Immunology, La Jolla, CA 92037, USA
| | - Vangipurapu Rajanikanth
- Division of Signaling and Gene Expression, La Jolla Institute for Allergy and Immunology, La Jolla, CA 92037, USA
| | - Patrick G Hogan
- Division of Signaling and Gene Expression, La Jolla Institute for Allergy and Immunology, La Jolla, CA 92037, USA; Program in Immunology, University of California, San Diego, La Jolla, CA 92037, USA.
| | - Aparna Gudlur
- Division of Signaling and Gene Expression, La Jolla Institute for Allergy and Immunology, La Jolla, CA 92037, USA
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Emrich SM, Yoast RE, Xin P, Zhang X, Pathak T, Nwokonko R, Gueguinou MF, Subedi KP, Zhou Y, Ambudkar IS, Hempel N, Machaca K, Gill DL, Trebak M. Cross-talk between N-terminal and C-terminal domains in stromal interaction molecule 2 (STIM2) determines enhanced STIM2 sensitivity. J Biol Chem 2019; 294:6318-6332. [PMID: 30824535 DOI: 10.1074/jbc.ra118.006801] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Revised: 02/28/2019] [Indexed: 12/20/2022] Open
Abstract
Store-operated Ca2+ entry (SOCE) is a ubiquitous pathway for Ca2+ influx across the plasma membrane (PM). SOCE is mediated by the endoplasmic reticulum (ER)-associated Ca2+-sensing proteins stromal interaction molecule 1 (STIM1) and STIM2, which transition into an active conformation in response to ER Ca2+ store depletion, thereby interacting with and gating PM-associated ORAI1 channels. Although structurally homologous, STIM1 and STIM2 generate distinct Ca2+ signatures in response to varying strengths of agonist stimulation. The physiological functions of these Ca2+ signatures, particularly under native conditions, remain unclear. To investigate the structural properties distinguishing STIM1 and STIM2 activation of ORAI1 channels under native conditions, here we used CRISPR/Cas9 to generate STIM1-/-, STIM2-/-, and STIM1/2-/- knockouts in HEK293 and colorectal HCT116 cells. We show that depending on cell type, STIM2 can significantly sustain SOCE in response to maximal store depletion. Utilizing the SOCE modifier 2-aminoethoxydiphenyl borate (2-APB), we demonstrate that 2-APB-activated store-independent Ca2+ entry is mediated exclusively by endogenous STIM2. Using variants that either stabilize or disrupt intramolecular interactions of STIM C termini, we show that the increased flexibility of the STIM2 C terminus contributes to its selective store-independent activation by 2-APB. However, STIM1 variants with enhanced flexibility in the C terminus failed to support its store-independent activation. STIM1/STIM2 chimeric constructs indicated that coordination between N-terminal sensitivity and C-terminal flexibility is required for specific store-independent STIM2 activation. Our results clarify the structural determinants underlying activation of specific STIM isoforms, insights that are potentially useful for isoform-selective drug targeting.
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Affiliation(s)
- Scott M Emrich
- From the Departments of Cellular and Molecular Physiology and
| | - Ryan E Yoast
- From the Departments of Cellular and Molecular Physiology and
| | - Ping Xin
- From the Departments of Cellular and Molecular Physiology and
| | - Xuexin Zhang
- From the Departments of Cellular and Molecular Physiology and
| | | | - Robert Nwokonko
- From the Departments of Cellular and Molecular Physiology and
| | | | - Krishna P Subedi
- the Secretory Physiology Section, NIDCR, National Institutes of Health, Bethesda, Maryland 20892, and
| | - Yandong Zhou
- From the Departments of Cellular and Molecular Physiology and
| | - Indu S Ambudkar
- the Secretory Physiology Section, NIDCR, National Institutes of Health, Bethesda, Maryland 20892, and
| | - Nadine Hempel
- Pharmacology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033
| | - Khaled Machaca
- the Department of Physiology and Biophysics, Weill Cornell Medical College in Qatar, Education City, Qatar Foundation, P.O. Box 24144, Doha, Qatar
| | - Donald L Gill
- From the Departments of Cellular and Molecular Physiology and
| | - Mohamed Trebak
- From the Departments of Cellular and Molecular Physiology and
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76
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Koenig X, Choi RH, Schicker K, Singh DP, Hilber K, Launikonis BS. Mechanistic insights into store-operated Ca 2+ entry during excitation-contraction coupling in skeletal muscle. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2019; 1866:1239-1248. [PMID: 30825472 DOI: 10.1016/j.bbamcr.2019.02.014] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Revised: 02/20/2019] [Accepted: 02/22/2019] [Indexed: 01/11/2023]
Abstract
Skeletal muscle fibres support store-operated Ca2+-entry (SOCE) across the t-tubular membrane upon exhaustive depletion of Ca2+ from the sarcoplasmic reticulum (SR). Recently we demonstrated the presence of a novel mode of SOCE activated under conditions of maintained [Ca2+]SR. This phasic SOCE manifested in a fast and transient manner in synchrony with excitation contraction (EC)-coupling mediated SR Ca2+-release (Communications Biology 1:31, doi: https://doi.org/10.1038/s42003-018-0033-7). Stromal interaction molecule 1 (STIM1) and calcium release-activated calcium channel 1 (ORAI1), positioned at the SR and t-system membranes, respectively, are the considered molecular correlate of SOCE. The evidence suggests that at the triads, where the terminal cisternae of the SR sandwich a t-tubule, STIM1 and ORAI1 proteins pre-position to allow for enhanced SOCE transduction. Here we show that phasic SOCE is not only shaped by global [Ca2+]SR but provide evidence for a local activation within nanodomains at the terminal cisternae of the SR. This feature may allow SOCE to modulate [Ca2+]SR during EC coupling. We define SOCE to occur on the same timescale as EC coupling and determine the temporal coherence of SOCE activation to SR Ca2+ release. We derive a delay of 0.3 ms reflecting diffusive Ca2+-equilibration at the luminal ryanodine receptor 1 (RyR1) channel mouth upon SR Ca2+-release. Numerical simulations of Ca2+-calsequestrin binding estimates a characteristic diffusion length and confines an upper limit for the spatial distance between STIM1 and RyR1. Experimental evidence for a 4- fold change in t-system Ca2+-permeability upon prolonged electrical stimulation in conjunction with numerical simulations of Ca2+-STIM1 binding suggests a Ca2+ dissociation constant of STIM1 below 0.35 mM. Our results show that phasic SOCE is intimately linked with RyR opening and closing, with only μs delays, because [Ca2+] in the terminal cisternae is just above the threshold for Ca2+ dissociation from STIM1 under physiological resting conditions. This article is part of a Special Issue entitled: ECS Meeting edited by Claus Heizmann, Joachim Krebs and Jacques Haiech.
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Affiliation(s)
- Xaver Koenig
- Center for Physiology and Pharmacology, Medical University of Vienna, Schwarzspanierstrasse 17, 1090 Wien, Austria.
| | - Rocky H Choi
- School of Biomedical Sciences, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Klaus Schicker
- Center for Physiology and Pharmacology, Medical University of Vienna, Schwarzspanierstrasse 17, 1090 Wien, Austria
| | - Daniel P Singh
- School of Biomedical Sciences, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Karlheinz Hilber
- Center for Physiology and Pharmacology, Medical University of Vienna, Schwarzspanierstrasse 17, 1090 Wien, Austria
| | - Bradley S Launikonis
- School of Biomedical Sciences, The University of Queensland, Brisbane, QLD 4072, Australia
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77
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Yen M, Lewis RS. Numbers count: How STIM and Orai stoichiometry affect store-operated calcium entry. Cell Calcium 2019; 79:35-43. [PMID: 30807904 DOI: 10.1016/j.ceca.2019.02.002] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Revised: 02/06/2019] [Accepted: 02/06/2019] [Indexed: 02/06/2023]
Abstract
Substantial progress has been made in the past several years in establishing the stoichiometries of STIM and Orai proteins and understanding their influence on store-operated calcium entry. Depletion of ER Ca2+ triggers STIM1 to accumulate at ER-plasma membrane junctions where it binds and opens Ca2+ release-activated Ca2+ (CRAC) channels. STIM1 is a dimer, and release of Ca2+ from its two luminal domains is reported to promote their association as well as drive formation of higher-order STIM1 oligomers. The CRAC channel, originally thought to be tetrameric, is now considered to be a hexamer of Orai1 subunits based on crystallographic and electrophysiological studies. STIM1 binding activates CRAC channels in a highly nonlinear way, such that all six Orai1 binding sites must be occupied to account for the activation and signature properties of native channels. The structural basis of STIM1 engagement with the channel is currently unclear, with evidence suggesting that STIM1 dimers bind to individual or pairs of Orai1 subunits. This review examines evidence that has led to points of consensus and debate about STIM1 and Orai1 stoichiometries, and explains the importance of STIM-Orai complex stoichiometry for the regulation of store-operated calcium entry.
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Affiliation(s)
- Michelle Yen
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, 94305, United States
| | - Richard S Lewis
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, 94305, United States.
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78
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Johnson M, Trebak M. ORAI channels in cellular remodeling of cardiorespiratory disease. Cell Calcium 2019; 79:1-10. [PMID: 30772685 DOI: 10.1016/j.ceca.2019.01.005] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Revised: 01/31/2019] [Accepted: 01/31/2019] [Indexed: 01/08/2023]
Abstract
Cardiorespiratory disease, which includes systemic arterial hypertension, restenosis, atherosclerosis, pulmonary arterial hypertension, asthma, and chronic obstructive pulmonary disease (COPD) are highly prevalent and devastating diseases with limited therapeutic modalities. A common pathophysiological theme to these diseases is cellular remodeling, which is contributed by changes in expression and activation of ion channels critical for either excitability or growth. Calcium (Ca2+) signaling and specifically ORAI Ca2+ channels have emerged as significant regulators of smooth muscle, endothelial, epithelial, platelet, and immune cell remodeling. This review details the dysregulation of ORAI in cardiorespiratory diseases, and how this dysregulation of ORAI contributes to cellular remodeling.
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Affiliation(s)
- Martin Johnson
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, PA 17033, United States
| | - Mohamed Trebak
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, PA 17033, United States.
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79
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Qiu R, Lewis RS. Structural features of STIM and Orai underlying store-operated calcium entry. Curr Opin Cell Biol 2019; 57:90-98. [PMID: 30716649 DOI: 10.1016/j.ceb.2018.12.012] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Revised: 12/20/2018] [Accepted: 12/21/2018] [Indexed: 12/16/2022]
Abstract
Store-operated calcium entry (SOCE) through Orai channels is triggered by receptor-stimulated depletion of Ca2+ from the ER. Orai1 is unique in terms of its activation mechanism, biophysical properties, and structure, and its precise regulation is essential for human health. Recent studies have begun to reveal the structural basis of the major steps in the SOCE pathway and how the system is reliably suppressed in resting cells but able to respond robustly to ER Ca2+ depletion. In this review, we discuss current models describing the activation of ER Ca2+ sensor STIM1, its binding to Orai1, propagation of the binding signal from the channel periphery to the central pore, and the resulting conformational changes underlying opening of the highly Ca2+ selective Orai1 channel.
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Affiliation(s)
- Ruoyi Qiu
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305, United States
| | - Richard S Lewis
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305, United States.
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80
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Tuning store-operated calcium entry to modulate Ca 2+-dependent physiological processes. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2018; 1866:1037-1045. [PMID: 30521873 DOI: 10.1016/j.bbamcr.2018.11.018] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Revised: 11/28/2018] [Accepted: 11/29/2018] [Indexed: 01/10/2023]
Abstract
The intracellular calcium signaling processes are tightly regulated to ensure the generation of calcium signals with the specific spatiotemporal characteristics required for regulating various cell functions. Compartmentalization of the molecular components involved in the generation of these signals at discrete intracellular sites ensures the signaling specificity and transduction fidelity of the signal for regulating downstream effector processes. Store-operated calcium entry (SOCE) is ubiquitously present in cells and is critical for essential cell functions in a variety of tissues. SOCE is mediated via plasma membrane Ca2+ channels that are activated when luminal [Ca2+] of the endoplasmic reticulum ([Ca2+]ER) is decreased. The ER-resident stromal interaction molecules, STIM1 and STIM2, respond to decreases in [Ca2+]ER by undergoing conformational changes that cause them to aggregate at the cell periphery in ER-plasma membrane (ER-PM) junctions. At these sites, STIM proteins recruit Orai1 channels and trigger their activation. Importantly, the two STIM proteins concertedly modulate Orai1 function as well as the sensitivity of SOCE to ER-Ca2+ store depletion. Another family of plasma membrane Ca2+ channels, known as the Transient Receptor Potential Canonical (TRPC) channels (TRPC1-7) also contribute to sustained [Ca2+]i elevation. Although Ca2+ signals generated by these channels overlap with those of Orai1, they regulate distinct functions in the cells. Importantly, STIM1 is also required for plasma membrane localization and activation of some TRPCs. In this review, we will discuss various molecular components and factors that govern the activation, regulation and modulation of the Ca2+ signal generated by Ca2+ entry pathways in response to depletion of ER-Ca2+ stores. This article is part of a Special Issue entitled: ECS Meeting edited by Claus Heizmann, Joachim Krebs and Jacques Haiech.
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81
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Stathopulos PB, Ikura M. Does stromal interaction molecule-1 have five senses? Cell Calcium 2018; 77:79-80. [PMID: 30528613 DOI: 10.1016/j.ceca.2018.12.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Revised: 12/01/2018] [Accepted: 12/01/2018] [Indexed: 01/04/2023]
Abstract
A single calcium (Ca2+) binding site within the canonical EF-hand loop was thought to govern the stromal interaction molecule-1 (STIM1) structural changes that lead to activation of Orai1 Ca2+ channels. Recent work by Gudlur et al., published in Nat Commun [9(1):4536], suggests that the STIM1 endoplasmic reticulum (ER) luminal domain has ∼5 additional Ca2+ binding sites, which underlie a surprising new proposal for Ca2+ sensing.
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Affiliation(s)
- Peter B Stathopulos
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, London, ON, N6A 5C1, Canada.
| | - Mitsuhiko Ikura
- Department of Medical Biophysics, University of Toronto, Princess Margaret Cancer Centre, University Health Network, Toronto, ON, M5G 2M9, Canada.
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82
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Wang WA, Agellon LB, Michalak M. Endoplasmic reticulum calcium dictates the distribution of intracellular unesterified cholesterol. Cell Calcium 2018; 76:116-121. [PMID: 30463032 DOI: 10.1016/j.ceca.2018.11.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Revised: 11/07/2018] [Accepted: 11/07/2018] [Indexed: 01/06/2023]
Abstract
Endoplasmic reticulum (ER) luminal Ca2+ influences many functions of this organelle, notably the synthesis and quality control of proteins and lipids. Cholesterol is an essential component of biological membranes and a precursor for many biologically important signaling molecules. The sterol regulatory element-binding proteins (SREBPs) are key regulators of lipid metabolism. These transcription factors are synthesized as ER membrane-bound precursor proteins that are proteolytically processed in response to cellular cholesterol status. Recently, ER Ca2+ status was shown to be an important determinant of the basal sensitivity of the sterol sensing mechanism inherent to the SREBP processing pathway. This article discusses the emerging relationship between cellular Ca2+ and cholesterol metabolism.
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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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83
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Pascual-Caro C, Espinosa-Bermejo N, Pozo-Guisado E, Martin-Romero FJ. Role of STIM1 in neurodegeneration. World J Biol Chem 2018; 9:16-24. [PMID: 30568747 PMCID: PMC6288638 DOI: 10.4331/wjbc.v9.i2.16] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/15/2018] [Revised: 10/08/2018] [Accepted: 10/23/2018] [Indexed: 02/05/2023] Open
Abstract
STIM1 is an endoplasmic reticulum (ER) protein with a key role in Ca2+ mobilization. Due to its ability to act as an ER-intraluminal Ca2+ sensor, it regulates store-operated Ca2+ entry (SOCE), which is a Ca2+ influx pathway involved in a wide variety of signalling pathways in eukaryotic cells. Despite its important role in Ca2+ transport, current knowledge about the role of STIM1 in neurons is much more limited. Growing evidence supports a role for STIM1 and SOCE in the preservation of dendritic spines required for long-term potentiation and the formation of memory. In this regard, recent studies have demonstrated that the loss of STIM1, which impairs Ca2+ mobilization in neurons, risks cell viability and could be the cause of neurodegenerative diseases. The role of STIM1 in neurodegeneration and the molecular basis of cell death triggered by low levels of STIM1 are discussed in this review.
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Affiliation(s)
- Carlos Pascual-Caro
- Department of Biochemistry and Molecular Biology, School of Life Sciences and Institute of Molecular Pathology Biomarkers, University of Extremadura, Badajoz 06006, Spain
| | - Noelia Espinosa-Bermejo
- Department of Biochemistry and Molecular Biology, School of Life Sciences and Institute of Molecular Pathology Biomarkers, University of Extremadura, Badajoz 06006, Spain
| | - Eulalia Pozo-Guisado
- Department of Cell Biology, School of Medicine and Institute of Molecular Pathology Biomarkers, University of Extremadura, Badajoz 06006, Spain
| | - Francisco Javier Martin-Romero
- Department of Biochemistry and Molecular Biology, School of Life Sciences and Institute of Molecular Pathology Biomarkers, University of Extremadura, Badajoz 06006, Spain
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84
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Zheng S, Ma G, He L, Zhang T, Li J, Yuan X, Nguyen NT, Huang Y, Zhang X, Gao P, Nwokonko R, Gill DL, Dong H, Zhou Y, Wang Y. Identification of molecular determinants that govern distinct STIM2 activation dynamics. PLoS Biol 2018; 16:e2006898. [PMID: 30444880 PMCID: PMC6267984 DOI: 10.1371/journal.pbio.2006898] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Revised: 11/30/2018] [Accepted: 10/31/2018] [Indexed: 12/22/2022] Open
Abstract
The endoplasmic reticulum (ER) Ca2+ sensors stromal interaction molecule 1 (STIM1) and STIM2, which connect ER Ca2+ depletion with extracellular Ca2+ influx, are crucial for the maintenance of Ca2+ homeostasis in mammalian cells. Despite the recent progress in unraveling the role of STIM2 in Ca2+ signaling, the mechanistic underpinnings of its activation remain underexplored. We use an engineering approach to direct ER-resident STIMs to the plasma membrane (PM) while maintaining their correct membrane topology, as well as Förster resonance energy transfer (FRET) sensors that enabled in cellulo real-time monitoring of STIM activities. This allowed us to determine the calcium affinities of STIM1 and STIM2 both in cellulo and in situ, explaining the current discrepancies in the literature. We also identified the key structural determinants, especially the corresponding G residue in STIM1, which define the distinct activation dynamics of STIM2. The chimeric E470G mutation could switch STIM2 from a slow and weak Orai channel activator into a fast and potent one like STIM1 and vice versa. The systemic dissection of STIM2 activation by protein engineering sets the stage for the elucidation of the regulation and function of STIM2-mediated signaling in mammals. Calcium ions play a major regulatory role in the physiology and biochemistry of the cell, and thus their levels and activities should be tightly regulated. The stromal interaction molecules (STIMs) are sensors of the calcium levels within the endoplasmic reticulum (ER)—which serves as a major intracellular calcium store—to mediate communication between the ER and the plasma membrane and are regarded as ubiquitous central players of calcium signaling in mammalian cells. STIM2 acts as a slow and weak activator of Orai1 calcium channels on the plasma membrane by direct binding; however, the affinity of STIMs for calcium or how Orai1 channels are activated remain unclear. In this study, we systematically analyzed the molecular determinants that govern the activation of STIM proteins. Adopting protein engineering approaches that enable the relocation of ER-resident STIM proteins at the plasma membrane, we determined the calcium affinities of STIMs under physiological conditions in mammalian cells. We identified a critical position within STIMs, which defines their distinct resting states and activation kinetics, as well as the efficacy to activate Orai1 channels. These findings shed new light on how STIM2 can efficiently respond to small changes within the ER lumen to regulate calcium homeostasis and signaling in mammalian cells.
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Affiliation(s)
- Sisi Zheng
- Beijing Key Laboratory of Gene Resource and Molecular Development, College of Life Sciences, Beijing Normal University, Beijing, P. R. China
| | - Guolin Ma
- Center for Translational Cancer Research, Institute of Biosciences and Technology, College of Medicine, Texas A&M University, Houston, Texas, United States of America
| | - Lian He
- Center for Translational Cancer Research, Institute of Biosciences and Technology, College of Medicine, Texas A&M University, Houston, Texas, United States of America
| | - Tian Zhang
- Beijing Key Laboratory of Gene Resource and Molecular Development, College of Life Sciences, Beijing Normal University, Beijing, P. R. China
| | - Jia Li
- Beijing Key Laboratory of Gene Resource and Molecular Development, College of Life Sciences, Beijing Normal University, Beijing, P. R. China
| | - Xiaoman Yuan
- Beijing Key Laboratory of Gene Resource and Molecular Development, College of Life Sciences, Beijing Normal University, Beijing, P. R. China
| | - Nhung T. Nguyen
- Center for Translational Cancer Research, Institute of Biosciences and Technology, College of Medicine, Texas A&M University, Houston, Texas, United States of America
| | - Yun Huang
- Center for Translational Cancer Research, Institute of Biosciences and Technology, College of Medicine, Texas A&M University, Houston, Texas, United States of America
| | - Xiaoyan Zhang
- Key Laboratory of Cell Proliferation and Regulation Biology, Ministry of Education, Institute of Cell Biology, College of Life Sciences, Beijing Normal University, Beijing, P. R. China
| | - Ping Gao
- Beijing Key Laboratory of Gene Resource and Molecular Development, College of Life Sciences, Beijing Normal University, Beijing, P. R. China
| | - Robert Nwokonko
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey Pennsylvania, United States of America
| | - Donald L. Gill
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey Pennsylvania, United States of America
| | - Hao Dong
- Kuang Yaming Honors School, Nanjing University, Nanjing, P. R. China
| | - Yubin Zhou
- Center for Translational Cancer Research, Institute of Biosciences and Technology, College of Medicine, Texas A&M University, Houston, Texas, United States of America
- Department of Medical Physiology, College of Medicine, Texas A&M University, Temple, Texas, United States of America
- * E-mail: (YZ); (YW)
| | - Youjun Wang
- Beijing Key Laboratory of Gene Resource and Molecular Development, College of Life Sciences, Beijing Normal University, Beijing, P. R. China
- * E-mail: (YZ); (YW)
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85
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Böhm J, Laporte J. [Tubular aggregate myopathy and Stormorken syndrome]. Med Sci (Paris) 2018; 34 Hors série n°2:26-31. [PMID: 30418142 DOI: 10.1051/medsci/201834s208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Calcium (Ca2+) is an essential regulator for a large number of cellular functions in various tissues and organs, and small disturbances of Ca2+ homeostasis can severely compromise normal physiology. Intracellular Ca2+ balance is mainly controlled by the reticular Ca2+ sensor STIM1 and the plasma membrane Ca2+ channel ORAI1 through a mechanism known as store-operated Ca2+ entry (SOCE). Gain-of-function mutations in STIM1 or ORAI1 cause excessive extracellular Ca2+ influx, resulting in tubular aggregate myopathy (TAM) and Stormorken syndrome (STRMK). Both disorders are spectra of the same disease and involve muscle weakness, miosis, thrombocytopenia, hyposplenism, ichthyosis, dyslexia, and short stature. Here we summarize the clinical and histological characteristics of both disorders, provide an overview on the genetic causes, and recapitulate the current knowledge on the pathomechanisms leading to the multi-systemic phenotype of tubular aggregate myopathy and Stormorken syndrome.
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Affiliation(s)
- Johann Böhm
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Illkirch, France - Centre National de la Recherche Scientifique (CNRS), UMR7104, Illkirch, France - Institut National de la Santé et de la Recherche Médicale (INSERM), U1258, Illkirch, France - Université de Strasbourg, Illkirch, France
| | - Jocelyn Laporte
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Illkirch, France - Centre National de la Recherche Scientifique (CNRS), UMR7104, Illkirch, France - Institut National de la Santé et de la Recherche Médicale (INSERM), U1258, Illkirch, France - Université de Strasbourg, Illkirch, France
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86
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Schober R, Waldherr L, Schmidt T, Graziani A, Stilianu C, Legat L, Groschner K, Schindl R. STIM1 and Orai1 regulate Ca 2+ microdomains for activation of transcription. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2018; 1866:1079-1091. [PMID: 30408546 DOI: 10.1016/j.bbamcr.2018.11.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Revised: 10/31/2018] [Accepted: 11/01/2018] [Indexed: 02/07/2023]
Abstract
Since calcium (Ca2+) regulates a large variety of cellular signaling processes in a cell's life, precise control of Ca2+ concentrations within the cell is essential. This enables the transduction of information via Ca2+ changes in a time-dependent and spatially defined manner. Here, we review molecular and functional aspects of how the store-operated Ca2+ channel Orai1 creates spatiotemporal Ca2+ microdomains. The architecture of this channel is unique, with a long helical pore and a six-fold symmetry. Energetic barriers within the Ca2+ channel pathway limit permeation to allow an extensive local Ca2+ increase in close proximity to the channel. The precise timing of the Orai1 channel function is controlled by direct binding to STIM proteins upon Ca2+ depletion in the endoplasmic reticulum. These induced Ca2+ microdomains are tailored to, and sufficient for, triggering long-term activation processes, such as transcription factor activation and subsequent gene regulation. We describe the principles of spatiotemporal activation of the transcription factor NFAT and compare its signaling characteristics to those of the autophagy regulating transcription factors, MITF and TFEB.
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Affiliation(s)
- Romana Schober
- Institute for Biophysics, Johannes Kepler University Linz, A-4040 Linz, Austria.
| | - Linda Waldherr
- Gottfried Schatz Research Center, Medical University of Graz, A-8010 Graz, Austria
| | - Tony Schmidt
- Gottfried Schatz Research Center, Medical University of Graz, A-8010 Graz, Austria
| | - Annarita Graziani
- Gottfried Schatz Research Center, Medical University of Graz, A-8010 Graz, Austria
| | - Clemens Stilianu
- Gottfried Schatz Research Center, Medical University of Graz, A-8010 Graz, Austria
| | - Lorenz Legat
- Gottfried Schatz Research Center, Medical University of Graz, A-8010 Graz, Austria
| | - Klaus Groschner
- Gottfried Schatz Research Center, Medical University of Graz, A-8010 Graz, Austria
| | - Rainer Schindl
- Gottfried Schatz Research Center, Medical University of Graz, A-8010 Graz, Austria.
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87
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Gudlur A, Zeraik AE, Hirve N, Rajanikanth V, Bobkov AA, Ma G, Zheng S, Wang Y, Zhou Y, Komives EA, Hogan PG. Calcium sensing by the STIM1 ER-luminal domain. Nat Commun 2018; 9:4536. [PMID: 30382093 PMCID: PMC6208404 DOI: 10.1038/s41467-018-06816-8] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Accepted: 09/26/2018] [Indexed: 12/22/2022] Open
Abstract
Stromal interaction molecule 1 (STIM1) monitors ER-luminal Ca2+ levels to maintain cellular Ca2+ balance and to support Ca2+ signalling. The prevailing view has been that STIM1 senses reduced ER Ca2+ through dissociation of bound Ca2+ from a single EF-hand site, which triggers a dramatic loss of secondary structure and dimerization of the STIM1 luminal domain. Here we find that the STIM1 luminal domain has 5-6 Ca2+-binding sites, that binding at these sites is energetically coupled to binding at the EF-hand site, and that Ca2+ dissociation controls a switch to a second structured conformation of the luminal domain rather than protein unfolding. Importantly, the other luminal-domain Ca2+-binding sites interact with the EF-hand site to control physiological activation of STIM1 in cells. These findings fundamentally revise our understanding of physiological Ca2+ sensing by STIM1, and highlight molecular mechanisms that govern the Ca2+ threshold for activation and the steep Ca2+ concentration dependence.
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Affiliation(s)
- Aparna Gudlur
- Division of Signalling and Gene Expression, La Jolla Institute for Allergy & Immunology, La Jolla, CA, 92037, USA
| | - Ana Eliza Zeraik
- Division of Signalling and Gene Expression, La Jolla Institute for Allergy & Immunology, La Jolla, CA, 92037, USA
- Instituto de Física de São Carlos, Universidade de São Paulo, São Carlos, CEP 13563-120, SP, Brazil
| | - Nupura Hirve
- Division of Signalling and Gene Expression, La Jolla Institute for Allergy & Immunology, La Jolla, CA, 92037, USA
| | - V Rajanikanth
- Division of Signalling and Gene Expression, La Jolla Institute for Allergy & Immunology, La Jolla, CA, 92037, USA
- H Lee Moffitt Cancer Center & Research Institute, Tampa, FL, 33612, USA
| | - Andrey A Bobkov
- Protein Production and Analysis Facility, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, 92037, USA
| | - Guolin Ma
- Center for Translational Cancer Research, Institute of Biosciences & Technology, College of Medicine, Texas A&M University, Houston, TX, 77030, USA
| | - Sisi Zheng
- Beijing Key Laboratory of Gene Resource and Molecular Development, College of Life Sciences, Beijing Normal University, Beijing, 100875, China
| | - Youjun Wang
- Beijing Key Laboratory of Gene Resource and Molecular Development, College of Life Sciences, Beijing Normal University, Beijing, 100875, China
| | - Yubin Zhou
- Center for Translational Cancer Research, Institute of Biosciences & Technology, College of Medicine, Texas A&M University, Houston, TX, 77030, USA
| | - Elizabeth A Komives
- Department of Chemistry and Biochemistry, University of California-San Diego, La Jolla, CA, 92037, USA
| | - Patrick G Hogan
- Division of Signalling and Gene Expression, La Jolla Institute for Allergy & Immunology, La Jolla, CA, 92037, USA.
- Program in Immunology, University of California-San Diego, La Jolla, CA, 92037, USA.
- Moores Cancer Center, University of California-San Diego, La Jolla, CA, 92093, USA.
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88
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The 2β Splice Variation Alters the Structure and Function of the Stromal Interaction Molecule Coiled-Coil Domains. Int J Mol Sci 2018; 19:ijms19113316. [PMID: 30366379 PMCID: PMC6274866 DOI: 10.3390/ijms19113316] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2018] [Revised: 10/21/2018] [Accepted: 10/22/2018] [Indexed: 12/16/2022] Open
Abstract
Stromal interaction molecule (STIM)-1 and -2 regulate agonist-induced and basal cytosolic calcium (Ca2+) levels after oligomerization and translocation to endoplasmic reticulum (ER)-plasma membrane (PM) junctions. At these junctions, the STIM cytosolic coiled-coil (CC) domains couple to PM Orai1 proteins and gate these Ca2+ release-activated Ca2+ (CRAC) channels, which facilitate store-operated Ca2+ entry (SOCE). Unlike STIM1 and STIM2, which are SOCE activators, the STIM2β splice variant contains an 8-residue insert located within the conserved CCs which inhibits SOCE. It remains unclear if the 2β insert further depotentiates weak STIM2 coupling to Orai1 or independently causes structural perturbations which prevent SOCE. Here, we use far-UV circular dichroism, light scattering, exposed hydrophobicity analysis, solution small angle X-ray scattering, and a chimeric STIM1/STIM2β functional assessment to provide insights into the molecular mechanism by which the 2β insert precludes SOCE activation. We find that the 2β insert reduces the overall α-helicity and enhances the exposed hydrophobicity of the STIM2 CC domains in the absence of a global conformational change. Remarkably, incorporation of the 2β insert into the STIM1 context not only affects the secondary structure and hydrophobicity as observed for STIM2, but also eliminates the more robust SOCE response mediated by STIM1. Collectively, our data show that the 2β insert directly precludes Orai1 channel activation by inducing structural perturbations in the STIM CC region.
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89
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Böhm J, Laporte J. Gain-of-function mutations in STIM1 and ORAI1 causing tubular aggregate myopathy and Stormorken syndrome. Cell Calcium 2018; 76:1-9. [PMID: 30243034 DOI: 10.1016/j.ceca.2018.07.008] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Revised: 07/26/2018] [Accepted: 07/26/2018] [Indexed: 11/16/2022]
Abstract
Calcium (Ca2+) is a key regulator for a large number of cellular functions in all kinds of cells, and small disturbances of Ca2+ homeostasis can severely compromise normal physiology in various tissues and organs. A major mechanism controlling Ca2+ homeostasis is store-operated Ca2+ entry (SOCE), which relies on the concerted action of the reticular Ca2+ sensor STIM1 and the plasma membrane Ca2+ channel ORAI1. Gain-of-function mutations in the respective genes induce excessive Ca2+ entry, and cause tubular aggregate myopathy (TAM) and Stormorken syndrome. Both disorders are part of a clinical continuum and involve muscle weakness and additional variably pronounced features including miosis, thrombocytopenia, hyposplenism, ichthyosis, dyslexia, and short stature. Mutations in the reticular Ca2+ buffer calsequestrin (CASQ1) have moreover been associated with the mild end of the TAM/Stormorken syndrome spectrum. Here we review the clinical and histological characteristics of both disorders, provide an overview on the genetic causes, and thereby focus on the pathomechanisms leading to muscle dysfunction and the multi-systemic phenotype of tubular aggregate myopathy and Stormorken syndrome.
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Affiliation(s)
- Johann Böhm
- Departement of Translational Medicine and Neurogenetics, IGBMC (Institut de Génétique et de Biologie Moléculaire et Cellulaire), Inserm U1258, CNRS UMR7104, Université de Strasbourg, Illkirch, France.
| | - Jocelyn Laporte
- Departement of Translational Medicine and Neurogenetics, IGBMC (Institut de Génétique et de Biologie Moléculaire et Cellulaire), Inserm U1258, CNRS UMR7104, Université de Strasbourg, Illkirch, France
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90
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Nguyen NT, Ma G, Lin E, D'Souza B, Jing J, He L, Huang Y, Zhou Y. CRAC channel-based optogenetics. Cell Calcium 2018; 75:79-88. [PMID: 30199756 DOI: 10.1016/j.ceca.2018.08.007] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Accepted: 08/31/2018] [Indexed: 01/28/2023]
Abstract
Store-operated Ca²+ entry (SOCE) constitutes a major Ca2+ influx pathway in mammals to regulate a myriad of physiological processes, including muscle contraction, synaptic transmission, gene expression, and metabolism. In non-excitable cells, the Ca²+ release-activated Ca²+ (CRAC) channel, composed of ORAI and stromal interaction molecules (STIM), constitutes a prototypical example of SOCE to mediate Ca2+ entry at specialized membrane contact sites (MCSs) between the endoplasmic reticulum (ER) and the plasma membrane (PM). The key steps of SOCE activation include the oligomerization of the luminal domain of the ER-resident Ca2+ sensor STIM1 upon Ca²+ store depletion, subsequent signal propagation toward the cytoplasmic domain to trigger a conformational switch and overcome the intramolecular autoinhibition, and ultimate exposure of the minimal ORAI-activating domain to directly engage and gate ORAI channels in the plasma membrane. This exquisitely coordinated cellular event is also facilitated by the C-terminal polybasic domain of STIM1, which physically associates with negatively charged phosphoinositides embedded in the inner leaflet of the PM to enable efficient translocation of STIM1 into ER-PM MCSs. Here, we present recent progress in recapitulating STIM1-mediated SOCE activation by engineering CRAC channels with optogenetic approaches. These STIM1-based optogenetic tools make it possible to not only mechanistically recapture the key molecular steps of SOCE activation, but also remotely and reversibly control Ca²+-dependent cellular processes, inter-organellar tethering at MCSs, and transcriptional reprogramming when combined with CRISPR/Cas9-based genome-editing tools.
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Affiliation(s)
- Nhung Thi Nguyen
- Center for Translational Cancer Research, Institute of Biosciences and Technology, College of Medicine, Texas A&M University, Houston, TX 77030, USA
| | - Guolin Ma
- Center for Translational Cancer Research, Institute of Biosciences and Technology, College of Medicine, Texas A&M University, Houston, TX 77030, USA
| | - Eena Lin
- Center for Translational Cancer Research, Institute of Biosciences and Technology, College of Medicine, Texas A&M University, Houston, TX 77030, USA
| | - Brendan D'Souza
- Center for Translational Cancer Research, Institute of Biosciences and Technology, College of Medicine, Texas A&M University, Houston, TX 77030, USA
| | - Ji Jing
- Center for Translational Cancer Research, Institute of Biosciences and Technology, College of Medicine, Texas A&M University, Houston, TX 77030, USA
| | - Lian He
- Center for Translational Cancer Research, Institute of Biosciences and Technology, College of Medicine, Texas A&M University, Houston, TX 77030, USA
| | - Yun Huang
- Center for Epigenetics and Disease Prevention, Institute of Biosciences and Technology, College of Medicine, Texas A&M University, Houston, TX 77030, USA; Department of Molecular and Cellular Medicine, College of Medicine, Texas A&M University, College Station, TX 77843, USA
| | - Yubin Zhou
- Center for Translational Cancer Research, Institute of Biosciences and Technology, College of Medicine, Texas A&M University, Houston, TX 77030, USA; Department of Medical Physiology, College of Medicine, Texas A&M University, Temple, TX 76504, USA.
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91
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Nguyen NT, Han W, Cao W, Wang Y, Wen S, Huang Y, Li M, Du L, Zhou Y. Store‐Operated Calcium Entry Mediated by ORAI and STIM. Compr Physiol 2018; 8:981-1002. [DOI: 10.1002/cphy.c170031] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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92
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Zhu J, Lu X, Feng Q, Stathopulos PB. A charge-sensing region in the stromal interaction molecule 1 luminal domain confers stabilization-mediated inhibition of SOCE in response to S-nitrosylation. J Biol Chem 2018; 293:8900-8911. [PMID: 29661937 PMCID: PMC5995509 DOI: 10.1074/jbc.ra117.000503] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Revised: 03/29/2018] [Indexed: 01/30/2023] Open
Abstract
Store-operated Ca2+ entry (SOCE) is a major Ca2+ signaling pathway facilitating extracellular Ca2+ influx in response to the initial release of intracellular endo/sarcoplasmic reticulum (ER/SR) Ca2+ stores. Stromal interaction molecule 1 (STIM1) is the Ca2+ sensor that activates SOCE following ER/SR Ca2+ depletion. The EF-hand and the adjacent sterile α-motif (EFSAM) domains of STIM1 are essential for detecting changes in luminal Ca2+ concentrations. Low ER Ca2+ levels trigger STIM1 destabilization and oligomerization, culminating in the opening of Orai1-composed Ca2+ channels on the plasma membrane. NO-mediated S-nitrosylation of cysteine thiols regulates myriad protein functions, but its effects on the structural mechanisms that regulate SOCE are unclear. Here, we demonstrate that S-nitrosylation of Cys49 and Cys56 in STIM1 enhances the thermodynamic stability of its luminal domain, resulting in suppressed hydrophobic exposure and diminished Ca2+ depletion-dependent oligomerization. Using solution NMR spectroscopy, we pinpointed a structural mechanism for STIM1 stabilization driven by complementary charge interactions between an electropositive patch on the core EFSAM domain and the S-nitrosylated nonconserved region of STIM1. Finally, using live cells, we found that the enhanced luminal domain stability conferred by either Cys49 and Cys56S-nitrosylation or incorporation of negatively charged residues into the EFSAM electropositive patch in the full-length STIM1 context significantly suppresses SOCE. Collectively, our results suggest that S-nitrosylation of STIM1 inhibits SOCE by interacting with an electropositive patch on the EFSAM core, which modulates the thermodynamic stability of the STIM1 luminal domain.
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Affiliation(s)
- Jinhui Zhu
- From the Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Xiangru Lu
- From the Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Qingping Feng
- From the Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Peter B Stathopulos
- From the Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario N6A 5C1, Canada
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93
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Rathner P, Stadlbauer M, Romanin C, Fahrner M, Derler I, Müller N. Rapid NMR-scale purification of 15N, 13C isotope-labeled recombinant human STIM1 coiled coil fragments. Protein Expr Purif 2018; 146:45-50. [PMID: 29414068 DOI: 10.1016/j.pep.2018.01.013] [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] [Received: 09/10/2017] [Revised: 01/05/2018] [Accepted: 01/24/2018] [Indexed: 10/17/2022]
Abstract
We report a new NMR-scale purification procedure for two recombinant wild type fragments of the stromal interaction molecule 1 (STIM1). This protein acts as a calcium sensor in the endoplasmic reticulum (ER) and extends into the cytosol accumulating at ER - plasma membrane (PM) junctions upon calcium store depletion ultimately leading to activation of the Orai/CRAC channel. The functionally relevant cytosolic part of STIM1 consists of three coiled coil domains, which are mainly involved in intra- and inter-molecular homomeric interactions as well as coupling to and gating of CRAC channels. The optimized one-step rapid purification procedure for two 15N,13C isotope-labeled cytosolic coiled coil fragments, which avoids the problems of previous approaches. The high yields of soluble well folded 15N,13C isotope-labeled cytosolic coiled coil fragments followed by detergent screening provide for initial NMR characterization of these domains. The longer 30.5 kDa fragment represents the largest STIM1 wild type fragment that has been recombinantly prepared and characterized in solution without need for mutation or refolding.
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Affiliation(s)
- Petr Rathner
- Institute of Organic Chemistry, Johannes Kepler University Linz, Altenbergerstraße 69, 4040 Linz, Austria
| | - Michael Stadlbauer
- Institute of Biophysics, Johannes Kepler University Linz, Gruberstraße 40, 4020 Linz, Austria
| | - Christoph Romanin
- Institute of Biophysics, Johannes Kepler University Linz, Gruberstraße 40, 4020 Linz, Austria
| | - Marc Fahrner
- Institute of Biophysics, Johannes Kepler University Linz, Gruberstraße 40, 4020 Linz, Austria
| | - Isabella Derler
- Institute of Biophysics, Johannes Kepler University Linz, Gruberstraße 40, 4020 Linz, Austria
| | - Norbert Müller
- Institute of Organic Chemistry, Johannes Kepler University Linz, Altenbergerstraße 69, 4040 Linz, Austria; Faculty of Science, University of South Bohemia, Branišovská 31, 370 05 České Budějovice, Czech Republic.
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94
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S -Nitrosylation of STIM1 by Neuronal Nitric Oxide Synthase Inhibits Store-Operated Ca 2+ Entry. J Mol Biol 2018; 430:1773-1785. [DOI: 10.1016/j.jmb.2018.04.028] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Revised: 03/28/2018] [Accepted: 04/19/2018] [Indexed: 11/18/2022]
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95
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Ma G, Zheng S, Ke Y, Zhou L, He L, Huang Y, Wang Y, Zhou Y. Molecular Determinants for STIM1 Activation During Store- Operated Ca2+ Entry. Curr Mol Med 2018; 17:60-69. [PMID: 28231751 DOI: 10.2174/1566524017666170220103731] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Revised: 01/31/2017] [Accepted: 02/01/2017] [Indexed: 12/25/2022]
Abstract
BACKGROUND STIM/ORAI-mediated store-operated Ca2+ entry (SOCE) mediates a myriad of Ca2+-dependent cellular activities in mammals. Genetic defects in STIM1/ORAI1 lead to devastating severe combined immunodeficiency; whereas gain-offunction mutations in STIM1/ORAI1 are intimately associated with tubular aggregate myopathy. At molecular level, a decrease in the Ca2+ concentrations within the lumen of endoplasmic reticulum (ER) initiates multimerization of the STIM1 luminal domain to switch on the STIM1 cytoplasmic domain to engage and gate ORAI channels, thereby leading to the ultimate Ca2+ influx from the extracellular space into the cytosol. Despite tremendous progress made in dissecting functional STIM1-ORAI1 coupling, the activation mechanism of SOCE remains to be fully characterized. OBJECTIVE AND METHODS Building upon a robust fluorescence resonance energy transfer assay designed to monitor STIM1 intramolecular autoinhibition, we aimed to systematically dissect the molecular determinants required for the activation and oligomerization of STIM1. RESULTS Here we showed that truncation of the STIM1 luminal domain predisposes STIM1 to adopt a more active conformation. Replacement of the single transmembrane (TM) domain of STIM1 by a more rigid dimerized TM domain of glycophorin A abolished STIM1 activation. But this adverse effect could be partially reversed by disrupting the TM dimerization interface. Moreover, our study revealed regions that are important for the optimal assembly of hetero-oligomers composed of full-length STIM1 with its minimal STIM1-ORAI activating region, SOAR. CONCLUSIONS Our study clarifies the roles of major STIM1 functional domains in maintaining a quiescent configuration of STIM1 to prevent preactivation of SOCE.
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Affiliation(s)
- G Ma
- Center for Translational Cancer Research, Institute of Biosciences and Technology, Texas A&M University, Houston, TX 77030. United States
| | - S Zheng
- Beijing Key Laboratory of Gene Resource and Molecular Development, College of Life Sciences, Beijing Normal University, Beijing 100875. China
| | - Y Ke
- Center for Translational Cancer Research, Institute of Biosciences and Technology, Texas A&M University, Houston, TX 77030. United States
| | - L Zhou
- Beijing Key Laboratory of Gene Resource and Molecular Development, College of Life Sciences, Beijing Normal University, Beijing 100875. China
| | - L He
- Center for Translational Cancer Research, Institute of Biosciences and Technology, Texas A&M University, Houston, TX 77030. United States
| | - Y Huang
- Center for Epigenetic and Disease Prevention, Institute of Biosciences and Technology, Texas A&M University, Houston, TX 77030. United States
| | - Y Wang
- Center for Translational Cancer Research, Institute of Biosciences and Technology, Texas A&M University System Health Science Center, 2121 W. Holcombe Blvd., Houston, TX 77030. United States
| | - Y Zhou
- Center for Translational Cancer Research, Institute of Biosciences and Technology, Texas A&M University System Health Science Center, 2121 W. Holcombe Blvd., Houston, TX 77030. United States
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96
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Novello MJ, Zhu J, Feng Q, Ikura M, Stathopulos PB. Structural elements of stromal interaction molecule function. Cell Calcium 2018; 73:88-94. [PMID: 29698850 DOI: 10.1016/j.ceca.2018.04.006] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Accepted: 04/13/2018] [Indexed: 02/02/2023]
Abstract
Stromal interaction molecule (STIM)-1 and -2 are multi-domain, single-pass transmembrane proteins involved in sensing changes in compartmentalized calcium (Ca2+) levels and transducing this cellular signal to Orai1 channel proteins. Our understanding of the molecular mechanisms underlying STIM signaling has been dramatically improved through available X-ray crystal and solution NMR structures. This high-resolution structural data has revealed that intricate intramolecular and intermolecular protein-protein interactions are involved in converting STIMs from the quiescent to activation-competent states. This review article summarizes the current high resolution structural data on specific EF-hand, sterile α motif and coiled-coil interactions which drive STIM function in the activation of Orai1 channels. Further, the work discusses the effects of post-translational modifications on the structure and function of STIMs. Future structural studies on larger STIM:Orai complexes will be critical to fully defining the molecular bases for STIM function and how post-translational modifications influence these mechanisms.
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Affiliation(s)
- Matthew J Novello
- Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada
| | - Jinhui Zhu
- Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada
| | - Qingping Feng
- Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada
| | - Mitsuhiko Ikura
- Princess Margaret Cancer Center, University Health Network, Toronto, Ontario, Canada.
| | - Peter B Stathopulos
- Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada.
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97
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McIvor E, Coombes S, Thul R. Three-dimensional spatio-temporal modelling of store operated Ca 2+ entry: Insights into ER refilling and the spatial signature of Ca 2+ signals. Cell Calcium 2018; 73:11-24. [PMID: 29880194 DOI: 10.1016/j.ceca.2018.03.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Revised: 03/29/2018] [Accepted: 03/30/2018] [Indexed: 11/19/2022]
Abstract
The spatial organisation of Orai channels and SERCA pumps within ER-PM junctions is important for enhancing the versatility and specificity of sub-cellular Ca2+ signals generated during store operated Ca2+ entry (SOCE). In this paper, we present a novel three dimensional spatio-temporal model describing Ca2+ dynamics in the ER-PM junction and sub-PM ER during SOCE. We investigate the role of Orai channel and SERCA pump location to provide insights into how these components shape the Ca2+ signals generated and affect ER refilling. We find that the organisation of Orai channels within the ER-PM junction controls the amplitude and shape of the Ca2+ profile but does not enhance ER refilling. The model shows that ER refilling is only weakly affected by the location of SERCA2b pumps within the ER-PM junction and that the placement of SERCA2a pumps within the ER-PM junction has much greater control over ER refilling.
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Affiliation(s)
- Emma McIvor
- Centre for Mathematical Medicine and Biology, School of Mathematical Sciences, University of Nottingham, University Park, Nottingham NG7 2RD, UK.
| | - Stephen Coombes
- Centre for Mathematical Medicine and Biology, School of Mathematical Sciences, University of Nottingham, University Park, Nottingham NG7 2RD, UK
| | - Rüdiger Thul
- Centre for Mathematical Medicine and Biology, School of Mathematical Sciences, University of Nottingham, University Park, Nottingham NG7 2RD, UK
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98
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Zhang L, Chao CH, Jaeger LA, Papp AB, Machaty Z. Calcium oscillations in fertilized pig oocytes are associated with repetitive interactions between STIM1 and ORAI1. Biol Reprod 2018; 98:510-519. [PMID: 29365044 PMCID: PMC5905661 DOI: 10.1093/biolre/ioy016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Revised: 12/01/2017] [Accepted: 01/19/2018] [Indexed: 11/15/2022] Open
Abstract
The Ca2+ entry mechanism that sustains the Ca2+ oscillations in fertilized pig oocytes was investigated. Stromal interaction molecule 1 (STIM1) and ORAI1 proteins tagged with various fluorophores were expressed in the oocytes. In some cells, the Ca2+ stores were depleted using cyclopiazonic acid (CPA); others were inseminated. Changes in the oocytes' cytosolic free Ca2+ concentration were monitored, while interaction between the expressed fusion proteins was investigated using fluorescence resonance energy transfer (FRET). Store depletion led to an increase of the FRET signal in oocytes co-expressing mVenus-STIM1 and mTurquoise2-ORAI1, indicating that Ca2+ release was followed by an interaction between these proteins. A similar FRET increase in response to CPA was also detected in oocytes co-expressing mVenus-STIM1 and mTurquoise2-STIM1, which is consistent with STIM1 forming punctae after store depletion. ML-9, an inhibitor that can interfere with STIM1 puncta formation, blocked store-operated Ca2+ entry (SOCE) induced by Ca2+ add-back after a CPA treatment; it also disrupted the Ca2+ oscillations in fertilized oocytes. In addition, oocytes overexpressing mVenus-STIM1 showed high-frequency Ca2+ oscillations when fertilized, arguing for an active role of the protein. High-frequency Ca2+ oscillations were also detected in fertilized oocytes co-expressing mVenus-STIM1 and mTurquoise2-ORAI1, and both of these high-frequency Ca2+ oscillations could be stopped by inhibitors of SOCE. Importantly, in oocytes co-expressing mVenus-STIM1 and mTurquoise2-ORAI1, we were also able to detect cyclic increases of the FRET signal indicating repetitive interactions between STIM1 and ORAI1. The results confirm the notion that in pig oocytes, SOCE is involved in the maintenance of the repetitive Ca2+ transients at fertilization.
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Affiliation(s)
- Lu Zhang
- Department of Animal Sciences, Purdue University, West Lafayette, Indiana, USA
| | | | - Laurie A Jaeger
- Department of Basic Medical Sciences, Purdue University, West Lafayette, Indiana, USA
| | - Agnes Bali Papp
- Department of Animal Sciences, Széchenyi István University, Győr, Hungary
| | - Zoltan Machaty
- Department of Animal Sciences, Purdue University, West Lafayette, Indiana, USA
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99
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Subedi KP, Ong HL, Son GY, Liu X, Ambudkar IS. STIM2 Induces Activated Conformation of STIM1 to Control Orai1 Function in ER-PM Junctions. Cell Rep 2018; 23:522-534. [DOI: 10.1016/j.celrep.2018.03.065] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Revised: 02/12/2018] [Accepted: 03/15/2018] [Indexed: 02/07/2023] Open
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100
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Palty R, Fu Z, Isacoff EY. Sequential Steps of CRAC Channel Activation. Cell Rep 2018; 19:1929-1939. [PMID: 28564609 DOI: 10.1016/j.celrep.2017.05.025] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2016] [Revised: 03/27/2017] [Accepted: 05/05/2017] [Indexed: 10/19/2022] Open
Abstract
Interaction between the endoplasmic reticulum protein STIM1 and the plasma membrane channel ORAI1 generates calcium signals that are central for diverse cellular functions. How STIM1 binds and activates ORAI1 remains poorly understood. Using electrophysiological, optical, and biochemical techniques, we examined the effects of mutations in the STIM1-ORAI1 activating region (SOAR) of STIM1. We find that SOAR mutants that are deficient in binding to resting ORAI1 channels are able to bind to and boost activation of partially activated ORAI1 channels. We further show that the STIM1 binding regions on ORAI1 undergo structural rearrangement during channel activation. The results suggest that activation of ORAI1 by SOAR occurs in multiple steps. In the first step, SOAR binds to ORAI1, partially activates the channel, and induces a rearrangement in the SOAR-binding site of ORAI1. That rearrangement of ORAI1 then permits sequential steps of SOAR binding, via distinct molecular interactions, to fully activate the channel.
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Affiliation(s)
- Raz Palty
- Department of Biochemistry, Ruth and Bruce Rappaport Faculty of Medicine, Technion - Israel Institute of Technology, Haifa 31096, Israel.
| | - Zhu Fu
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Ehud Y Isacoff
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA; Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA 94720, USA; Bioscience Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
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