101
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Cui C, Merritt R, Fu L, Pan Z. Targeting calcium signaling in cancer therapy. Acta Pharm Sin B 2017; 7:3-17. [PMID: 28119804 PMCID: PMC5237760 DOI: 10.1016/j.apsb.2016.11.001] [Citation(s) in RCA: 377] [Impact Index Per Article: 53.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2016] [Accepted: 10/28/2016] [Indexed: 12/15/2022] Open
Abstract
The intracellular calcium ions (Ca2+) act as second messenger to regulate gene transcription, cell proliferation, migration and death. Accumulating evidences have demonstrated that intracellular Ca2+ homeostasis is altered in cancer cells and the alteration is involved in tumor initiation, angiogenesis, progression and metastasis. Targeting derailed Ca2+ signaling for cancer therapy has become an emerging research area. This review summarizes some important Ca2+ channels, transporters and Ca2+-ATPases, which have been reported to be altered in human cancer patients. It discusses the current research effort toward evaluation of the blockers, inhibitors or regulators for Ca2+ channels/transporters or Ca2+-ATPase pumps as anti-cancer drugs. This review is also aimed to stimulate interest in, and support for research into the understanding of cellular mechanisms underlying the regulation of Ca2+ signaling in different cancer cells, and to search for novel therapies to cure these malignancies by targeting Ca2+ channels or transporters.
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Key Words
- 20-GPPD, 20-O-β-D-glucopyranosyl-20(S)-protopanaxadiol
- Apoptosis
- CBD, cannabidiol
- CBG, cannabigerol
- CPZ, capsazepine
- CRAC, Ca2+ release-activated Ca2+ channel
- CTL, cytotoxic T cells
- CYP3A4, cytochrome P450 3A4
- Ca2+ channels
- CaM, calmodulin
- CaMKII, calmodulin-dependent protein kinase II
- Cancer therapy
- Cell proliferation
- Channel blockers;
- ER/SR, endoplasmic/sarcoplasmic reticulum
- HCX, H+/Ca2+ exchangers
- IP3, inositol 1,4,5-trisphosphate
- IP3R (1, 2, 3), IP3 receptor (type 1, type 2, type 3)
- MCU, mitochondrial Ca2+ uniporter
- MCUR1, MCU uniporter regulator 1
- MICU (1, 2, 3), mitochondrial calcium uptake (type 1, type 2, type 3)
- MLCK, myosin light-chain kinase
- Migration
- NCX, Na+/Ca2+ exchanger
- NF-κB, nuclear factor-κB
- NFAT, nuclear factor of activated T cells
- NSCLC, non-small cell lung cancer
- OSCC, oral squamous cell carcinoma cells
- PKC, protein kinase C
- PM, plasma membrane
- PMCA, plasma membrane Ca2+-ATPase
- PTP, permeability transition pore
- ROS, reactive oxygen species
- RyR, ryanodine receptor
- SERCA, SR/ER Ca2+-ATPase
- SOCE, store-operated Ca2+ entry
- SPCA, secretory pathway Ca2+-ATPase
- Store-operated Ca2+ entry
- TEA, tetraethylammonium
- TG, thapsigargin
- TPC2, two-pore channel 2
- TRIM, 1-(2-(trifluoromethyl) phenyl) imidazole
- TRP (A, C, M, ML, N, P, V), transient receptor potential (ankyrin, canonical, melastatin, mucolipin, no mechanoreceptor potential C, polycystic, vanilloid)
- VGCC, voltage-gated Ca2+ channel
- mAb, monoclonal antibody
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Affiliation(s)
- Chaochu Cui
- State Key Laboratory of Oncology in South China; Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou 510060, China
- Department of Surgery, Division of Thoracic Surgery, The Ohio State University, Columbus, OH 43210, USA
| | - Robert Merritt
- Department of Surgery, Division of Thoracic Surgery, The Ohio State University, Columbus, OH 43210, USA
- Comprehensive Cancer Center, The Ohio State University, Columbus, OH 43210, USA
| | - Liwu Fu
- State Key Laboratory of Oncology in South China; Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou 510060, China
| | - Zui Pan
- Department of Surgery, Division of Thoracic Surgery, The Ohio State University, Columbus, OH 43210, USA
- Comprehensive Cancer Center, The Ohio State University, Columbus, OH 43210, USA
- College of Nursing and Health Innovation, The University of Texas at Arlington, Arlington, TX 76019, USA
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102
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The STIM1-binding site nexus remotely controls Orai1 channel gating. Nat Commun 2016; 7:13725. [PMID: 27929067 PMCID: PMC5155162 DOI: 10.1038/ncomms13725] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Accepted: 10/26/2016] [Indexed: 01/17/2023] Open
Abstract
The ubiquitously expressed Orai Ca2+ channels are gated through a unique process of intermembrane coupling with the Ca2+-sensing STIM proteins. Despite the significance of Orai1-mediated Ca2+ signals, how gating of Orai1 is triggered by STIM1 remains unknown. A widely held gating model invokes STIM1 binding directly to Orai1 pore-forming helix. Here we report that an Orai1 C-terminal STIM1-binding site, situated far from the N-terminal pore helix, alone provides the trigger that is necessary and sufficient for channel gating. We identify a critical ‘nexus' within Orai1 connecting the peripheral C-terminal STIM1-binding site to the Orai1 core helices. Mutation of the nexus transforms Orai1 into a persistently open state exactly mimicking the action of STIM1. We suggest that the Orai1 nexus transduces the STIM1-binding signal through a conformational change in the inner core helices, and that STIM1 remotely gates the Orai1 channel without the necessity for direct STIM1 contact with the pore-forming helix.
How plasma membrane Orai Ca2+ channels are activated by STIM proteins to activate Ca2+ signals is still not fully known. Here the authors show that a nexus region located at the Orai1 C-terminus allows channel gating without a direct interaction of STIM1 with the channel pore.
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103
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Ali S, Xu T, Xu X. CRAC channel gating and its modulation by STIM1 and 2-aminoethoxydiphenyl borate. J Physiol 2016; 595:3085-3095. [PMID: 27753099 DOI: 10.1113/jp273130] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2016] [Accepted: 10/27/2016] [Indexed: 11/08/2022] Open
Abstract
Ca2+ release-activated Ca2+ (CRAC) channels play an essential role in the immune system. The pore-forming subunit, Orai1, is an important pharmacological target. Here, we summarize the recent discoveries on the structure-function relationship of Orai1, as well as its interaction with the native channel opener STIM1 and chemical modulator 2-aminoethoxydiphenyl borate (2-APB). We first introduce the critical structural elements of Orai1, which include a Ca2+ accumulating region, ion selectivity filter, hydrophobic centre, basic region, extended transmembrane Orai1 N-terminal (ETON) region, transmembrane (TM) regions 2 and 3, P245 bend, 263 SHK265 hinge linker and L273-L276 hydrophobic patch. We then hypothesize the possible mechanisms by which STIM1 triggers the conformational transitions of TM regions and exquisitely shapes the ion conduction pathway during generation of the CRAC current (Icrac ) with high Ca2+ selectivity. Finally, we propose mechanisms by which 2-APB modulates Icrac . On the STIM1-activated Orai1 channel, a low dose of 2-APB acts directly, dilating its extremely narrow pore diameter from 3.8 to 4.6 Å, increasing its unitary channel conductance, and potentiating the Icrac . Further elucidation of the structure of the opened CRAC channel and a better understanding of structure-function relationship will benefit the future development of novel immune modulators.
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Affiliation(s)
- Sher Ali
- National Key Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China.,University of Chinese Academy of Science, Beijing, 100049, China
| | - Tao Xu
- National Key Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China
| | - Xiaolan Xu
- National Key Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China
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104
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Cai X, Zhou Y, Nwokonko RM, Loktionova NA, Wang X, Xin P, Trebak M, Wang Y, Gill DL. The Orai1 Store-operated Calcium Channel Functions as a Hexamer. J Biol Chem 2016; 291:25764-25775. [PMID: 27780862 DOI: 10.1074/jbc.m116.758813] [Citation(s) in RCA: 86] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Revised: 10/17/2016] [Indexed: 12/17/2022] Open
Abstract
Orai channels mediate store-operated Ca2+ signals crucial in regulating transcription in many cell types, and implicated in numerous immunological and inflammatory disorders. Despite their central importance, controversy surrounds the basic subunit structure of Orai channels, with several biochemical and biophysical studies suggesting a tetrameric structure yet crystallographic evidence indicating a hexamer. We systematically investigated the subunit configuration of the functional Orai1 channel, generating a series of tdTomato-tagged concatenated Orai1 channel constructs (dimers to hexamers) expressed in CRISPR-derived ORAI1 knock-out HEK cells, stably expressing STIM1-YFP. Surface biotinylation demonstrated that the full-length concatemers were surface membrane-expressed. Unexpectedly, Orai1 dimers, trimers, tetramers, pentamers, and hexamers all mediated similar and substantial store-operated Ca2+ entry. Moreover, each Orai1 concatemer mediated Ca2+ currents with inward rectification and reversal potentials almost identical to those observed with expressed Orai1 monomer. In Orai1 tetramers, subunit-specific replacement with Orai1 E106A "pore-inactive" subunits revealed that functional channels utilize only the N-terminal dimer from the tetramer. In contrast, Orai1 E106A replacement in Orai1 hexamers established that all the subunits can contribute to channel formation, indicating a hexameric channel configuration. The critical Ca2+ selectivity filter-forming Glu-106 residue may mediate Orai1 channel assembly around a central Ca2+ ion within the pore. Thus, multiple E106A substitutions in the Orai1 hexamer may promote an alternative "trimer-of-dimers" channel configuration in which the C-terminal E106A subunits are excluded from the hexameric core. Our results argue strongly against a tetrameric configuration for Orai1 channels and indicate that the Orai1 channel functions as a hexamer.
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Affiliation(s)
- Xiangyu Cai
- From the Department of Cellular and Molecular Physiology, the Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033 and
| | - Yandong Zhou
- From the Department of Cellular and Molecular Physiology, the Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033 and
| | - Robert M Nwokonko
- From the Department of Cellular and Molecular Physiology, the Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033 and
| | - Natalia A Loktionova
- From the Department of Cellular and Molecular Physiology, the Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033 and
| | - Xianming Wang
- From the Department of Cellular and Molecular Physiology, the Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033 and
| | - Ping Xin
- From the Department of Cellular and Molecular Physiology, the Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033 and
| | - Mohamed Trebak
- From the Department of Cellular and Molecular Physiology, the Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033 and
| | - Youjun Wang
- the Beijing Key Laboratory of Gene Resources and Molecular Development, College of Life Sciences, Beijing Normal University, Beijing 100875, China
| | - Donald L Gill
- From the Department of Cellular and Molecular Physiology, the Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033 and
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105
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Mullins FM, Yen M, Lewis RS. Orai1 pore residues control CRAC channel inactivation independently of calmodulin. ACTA ACUST UNITED AC 2016; 147:137-52. [PMID: 26809793 PMCID: PMC4727942 DOI: 10.1085/jgp.201511437] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Researchers have reevaluated the role of calmodulin and previously identified calmodulin binding sites in the mechanism by which Ca2+-release activated Ca2+ channels can be inactivated as Ca2+ ions enter cells. Ca2+ entry through CRAC channels causes fast Ca2+-dependent inactivation (CDI). Previous mutagenesis studies have implicated Orai1 residues W76 and Y80 in CDI through their role in binding calmodulin (CaM), in agreement with the crystal structure of Ca2+–CaM bound to an Orai1 N-terminal peptide. However, a subsequent Drosophila melanogaster Orai crystal structure raises concerns about this model, as the side chains of W76 and Y80 are predicted to face the pore lumen and create a steric clash between bound CaM and other Orai1 pore helices. We further tested the functional role of CaM using several dominant-negative CaM mutants, none of which affected CDI. Given this evidence against a role for pretethered CaM, we altered side-chain volume and charge at the Y80 and W76 positions to better understand their roles in CDI. Small side chain volume had different effects at the two positions: it accelerated CDI at position Y80 but reduced the extent of CDI at position W76. Positive charges at Y80 and W76 permitted partial CDI with accelerated kinetics, whereas introducing negative charge at any of five consecutive pore-lining residues (W76, Y80, R83, K87, or R91) completely eliminated CDI. Noise analysis of Orai1 Y80E and Y80K currents indicated that reductions in CDI for these mutations could not be accounted for by changes in unitary current or open probability. The sensitivity of CDI to negative charge introduced into the pore suggested a possible role for anion binding in the pore. However, although Cl− modulated the kinetics and extent of CDI, we found no evidence that CDI requires any single diffusible cytosolic anion. Together, our results argue against a CDI mechanism involving CaM binding to W76 and Y80, and instead support a model in which Orai1 residues Y80 and W76 enable conformational changes within the pore, leading to CRAC channel inactivation.
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Affiliation(s)
- Franklin M Mullins
- Department of Pathology and Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305
| | - Michelle Yen
- Department of Pathology and Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305
| | - Richard S Lewis
- Department of Pathology and Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305
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106
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Mullins FM, Lewis RS. The inactivation domain of STIM1 is functionally coupled with the Orai1 pore to enable Ca2+-dependent inactivation. ACTA ACUST UNITED AC 2016; 147:153-64. [PMID: 26809794 PMCID: PMC4727943 DOI: 10.1085/jgp.201511438] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The inactivation domain of STIM1 (ID(STIM): amino acids 470-491) has been described as necessary for Ca(2+)-dependent inactivation (CDI) of Ca(2+) release-activated Ca(2+) (CRAC) channels, but its mechanism of action is unknown. Here we identify acidic residues within IDSTIM that control the extent of CDI and examine functional interactions of ID(STIM) with Orai1 pore residues W76 and Y80. Alanine scanning revealed three IDSTIM residues (D476/D478/D479) that are critical for generating full CDI. Disabling ID(STIM) by a triple alanine substitution for these three residues ("STIM1 3A") or by truncation of the entire domain (STIM1(1-469)) reduced CDI to the same residual level observed for the Orai1 pore mutant W76A (approximately one third of the extent seen with full-length STIM1). Results of noise analysis showed that STIM11-469 and Orai1 W76A mutants do not reduce channel open probability or unitary Ca(2+) conductance, factors that determine local Ca(2+) accumulation, suggesting that they diminish CDI instead by inhibiting the CDI gating mechanism. We tested for functional coupling between ID(STIM) and the Orai1 pore by double-mutant cycle analysis. The effects on CDI of mutations disabling ID(STIM) or W76 were not additive, demonstrating that ID(STIM) and W76 are strongly coupled and act in concert to generate full-strength CDI. Interestingly, disabling ID(STIM) and W76 separately gave opposite results in Orai1 Y80A channels: channels with W76 but lacking ID(STIM) generated approximately two thirds of the WT extent of CDI but those with ID(STIM) but lacking W76 completely failed to inactivate. Together, our results suggest that Y80 alone is sufficient to generate residual CDI, but acts as a barrier to full CDI. Although ID(STIM) is not required as a Ca(2+) sensor for CDI, it acts in concert with W76 to progress beyond the residual inactivated state and enable CRAC channels to reach the full extent of inactivation.
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Affiliation(s)
- Franklin M Mullins
- Department of Pathology and Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305
| | - Richard S Lewis
- Department of Pathology and Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305
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107
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Wei M, Zhou Y, Sun A, Ma G, He L, Zhou L, Zhang S, Liu J, Zhang SL, Gill DL, Wang Y. Molecular mechanisms underlying inhibition of STIM1-Orai1-mediated Ca 2+ entry induced by 2-aminoethoxydiphenyl borate. Pflugers Arch 2016; 468:2061-2074. [PMID: 27726010 DOI: 10.1007/s00424-016-1880-z] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Revised: 08/24/2016] [Accepted: 09/07/2016] [Indexed: 01/25/2023]
Abstract
Store-operated Ca2+ entry (SOCE) mediated by STIM1 and Orai1 is crucial for Ca2+ signaling and homeostasis in most cell types. 2-Aminoethoxydiphenyl borate (2-APB) is a well-described SOCE inhibitor, but its mechanisms of action remain largely elusive. Here, we show that 2-APB does not affect the dimeric state of STIM1, but enhances the intramolecular coupling between the coiled-coil 1 (CC1) and STIM-Orai-activating region (SOAR) of STIM1, with subsequent reduction in the formation of STIM1 puncta in the absence of Orai1 overexpression. 2-APB also inhibits Orai1 channels, directly inhibiting Ca2+ entry through the constitutively active, STIM1-independent Orai1 mutants, Orai1-P245T and Orai1-V102A. When unbound from STIM1, the constitutively active Orai1-V102C mutant is not inhibited by 2-APB. Thus, we used Orai1-V012C as a tool to examine whether 2-APB can also inhibit the coupling between STIM1 and Orai1. We reveal that the functional coupling between STIM1 and Orai1-V102C is inhibited by 2-APB. This inhibition on coupling is indirect, arising from 2-APB's action on STIM1, and it is most likely mediated by functional channel residues in the Orai1 N-terminus. Overall, our findings on this two-site inhibition mediated by 2-APB provide new understanding on Orai1-activation by STIM1, important to future drug design.
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Affiliation(s)
- Ming Wei
- Beijing Key Laboratory of Gene Resources and Molecular Development, College of Life Sciences, Beijing Normal University, Beijing, 100875, People's Republic of China
| | - Yandong Zhou
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, PA, 17033, USA
| | - Aomin Sun
- Beijing Key Laboratory of Gene Resources and Molecular Development, College of Life Sciences, Beijing Normal University, Beijing, 100875, People's Republic of China
| | - Guolin Ma
- Institute of Biosciences and Technology, Texas A&M University Health Science Center, Houston, TX, 77030, USA
| | - Lian He
- Institute of Biosciences and Technology, Texas A&M University Health Science Center, Houston, TX, 77030, USA
| | - Lijuan Zhou
- Beijing Key Laboratory of Gene Resources and Molecular Development, College of Life Sciences, Beijing Normal University, Beijing, 100875, People's Republic of China
| | - Shuce Zhang
- Beijing Key Laboratory of Gene Resources and Molecular Development, College of Life Sciences, Beijing Normal University, Beijing, 100875, People's Republic of China
| | - Jin Liu
- Beijing Key Laboratory of Gene Resources and Molecular Development, College of Life Sciences, Beijing Normal University, Beijing, 100875, People's Republic of China
| | - Shenyuan L Zhang
- Department of Medical Physiology, College of Medicine, Texas A&M University Health Science Center, Temple, TX, 76504, USA
| | - Donald L Gill
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, PA, 17033, USA.
| | - Youjun Wang
- Beijing Key Laboratory of Gene Resources and Molecular Development, College of Life Sciences, Beijing Normal University, Beijing, 100875, People's Republic of China.
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108
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Jairaman A, Maguire CH, Schleimer RP, Prakriya M. Allergens stimulate store-operated calcium entry and cytokine production in airway epithelial cells. Sci Rep 2016; 6:32311. [PMID: 27604412 PMCID: PMC5015156 DOI: 10.1038/srep32311] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Accepted: 08/05/2016] [Indexed: 01/01/2023] Open
Abstract
Aberrant immune responses to environmental allergens including insect allergens from house dust mites and cockroaches contribute to allergic inflammatory diseases such as asthma in susceptible individuals. Airway epithelial cells (AECs) play a critical role in this process by sensing the proteolytic activity of allergens via protease-activated receptors (PAR2) to initiate inflammatory and immune responses in the airway. Elevation of cytosolic Ca2+ is an important signaling event in this process, yet the fundamental mechanism by which allergens induce Ca2+ elevations in AECs remains poorly understood. Here we find that extracts from dust mite and cockroach induce sustained Ca2+ elevations in AECs through the activation of Ca2+ release-activated Ca2+ (CRAC) channels encoded by Orai1 and STIM1. CRAC channel activation occurs, at least in part, through allergen mediated stimulation of PAR2 receptors. The ensuing Ca2+ entry then activates NFAT/calcineurin signaling to induce transcriptional production of the proinflammatory cytokines IL-6 and IL-8. These findings highlight a key role for CRAC channels as regulators of allergen induced inflammatory responses in the airway.
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Affiliation(s)
- Amit Jairaman
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, IL 60611, Chicago, USA
| | - Chelsea H Maguire
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, IL 60611, Chicago, USA
| | - Robert P Schleimer
- Division of Allergy-Immunology, Department of Medicine, Northwestern University Feinberg School of Medicine, IL 60611, Chicago, USA
| | - Murali Prakriya
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, IL 60611, Chicago, USA
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109
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Xu X, Ali S, Li Y, Yu H, Zhang M, Lu J, Xu T. 2-Aminoethoxydiphenyl Borate Potentiates CRAC Current by Directly Dilating the Pore of Open Orai1. Sci Rep 2016; 6:29304. [PMID: 27373367 PMCID: PMC4931693 DOI: 10.1038/srep29304] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Accepted: 06/17/2016] [Indexed: 12/14/2022] Open
Abstract
2-Aminoethoxydiphenyl borate (2-APB) elicits potentiation current (Ip) on Ca2+ release-activated Ca2+ (CRAC) channels. An accurate investigation into this modulation mechanism would reveal how STIM1-dependent channel gating is enhanced, and benefit the future immune enhancer development. Here, we directly probed the pore diameter of CRAC channels and found that 2-APB enlarged the pore size of STIM1-activated Orai1 from 3.8 to 4.6 Å. We demonstrated that ions with small sizes, i.e., Ca2+ and Na+, mediated prominent 2-APB-induced Ip on the wildtype (WT) Orai1 channels of narrow pore sizes, while conducted decreased or no Ip on Orai1-V102C/A/G mutant channels with enlarged pore diameters. On the contrary, large Cs+ ions blocked the WT channels, while displayed large 2-APB induced Ip on pore-enlarged Orai1-V102C/A/G mutant channels, and the potentiation ratio was highest on Orai1-V102C with an intermediate pore size. Furthermore, we showed that 2-APB potentiated Cs+ current on constitutively active Orai1-V102C/A/G mutants independent of STIM1. Our data suggest that 2-APB directly dilates the pore of open Orai1 channels, both ion size and pore diameter jointly determine the amplitude of Ip on CRAC channels, and the generation of Ip requires the open state of Orai1, not STIM1 itself.
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Affiliation(s)
- Xiaolan Xu
- National Key Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Sher Ali
- National Key Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.,University of Chinese Academy of Science, Beijing 100049, China
| | - Yufeng Li
- National Key Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.,College of Life Science, Sichuan Normal University, Chengdu 610101, China
| | - Haijie Yu
- Department of Physiology and Biophysics, University of Washington, Seattle, WA, USA
| | - Mingshu Zhang
- Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Jingze Lu
- National Key Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Tao Xu
- National Key Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
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110
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Li P, Miao Y, Dani A, Vig M. α-SNAP regulates dynamic, on-site assembly and calcium selectivity of Orai1 channels. Mol Biol Cell 2016; 27:2542-53. [PMID: 27335124 PMCID: PMC4985256 DOI: 10.1091/mbc.e16-03-0163] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Accepted: 06/17/2016] [Indexed: 01/01/2023] Open
Abstract
Ion channel subunits typically assemble in the endoplasmic reticulum. α-SNAP orchestrates a unique assembly and calcium selectivity of Orai1 subunits into functional multimers. Dynamic assembly of Orai1 and its dependence on α-SNAP could enable localization of calcium signals and regulation of rate and amount of calcium influx. Orai1 forms a highly calcium-selective pore of the calcium release activated channel, and α-SNAP is necessary for its function. Here we show that α-SNAP regulates on-site assembly of Orai1 dimers into calcium-selective multimers. We find that Orai1 is a dimer in resting primary mouse embryonic fibroblasts but displays variable stoichiometry in the plasma membrane of store-depleted cells. Remarkably, α-SNAP depletion induces formation of higher-order Orai1 oligomers, which permeate significant levels of sodium via Orai1 channels. Sodium permeation in α-SNAP–deficient cells cannot be corrected by tethering multiple Stim1 domains to Orai1 C-terminal tail, demonstrating that α-SNAP regulates functional assembly and calcium selectivity of Orai1 multimers independently of Stim1 levels. Fluorescence nanoscopy reveals sustained coassociation of α-SNAP with Stim1 and Orai1, and α-SNAP–depleted cells show faster and less constrained mobility of Orai1 within ER-PM junctions, suggesting Orai1 and Stim1 coentrapment without stable contacts. Furthermore, α-SNAP depletion significantly reduces fluorescence resonance energy transfer between Stim1 and Orai1 N-terminus but not C-terminus. Taken together, these data reveal a unique role of α-SNAP in the on-site functional assembly of Orai1 subunits and suggest that this process may, in part, involve enabling crucial low-affinity interactions between Orai1 N-terminus and Stim1.
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Affiliation(s)
- Peiyao Li
- Department of Pathology and Immunology, School of Medicine, Washington University in St. Louis, St. Louis, MO 63110
| | - Yong Miao
- Department of Pathology and Immunology, School of Medicine, Washington University in St. Louis, St. Louis, MO 63110
| | - Adish Dani
- Department of Pathology and Immunology, School of Medicine, Washington University in St. Louis, St. Louis, MO 63110 Hope Center for Neurological Disorders, School of Medicine, Washington University in St. Louis, St. Louis, MO 63110
| | - Monika Vig
- Department of Pathology and Immunology, School of Medicine, Washington University in St. Louis, St. Louis, MO 63110
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111
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Deb BK, Pathak T, Hasan G. Store-independent modulation of Ca(2+) entry through Orai by Septin 7. Nat Commun 2016; 7:11751. [PMID: 27225060 PMCID: PMC4894974 DOI: 10.1038/ncomms11751] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Accepted: 04/26/2016] [Indexed: 01/07/2023] Open
Abstract
Orai channels are required for store-operated Ca2+ entry (SOCE) in multiple cell types. Septins are a class of GTP-binding proteins that function as diffusion barriers in cells. Here we show that Septin 7 acts as a ‘molecular brake’ on activation of Orai channels in Drosophila neurons. Lowering Septin 7 levels results in dOrai-mediated Ca2+ entry and higher cytosolic Ca2+ in resting neurons. This Ca2+ entry is independent of depletion of endoplasmic reticulum Ca2+ stores and Ca2+ release through the inositol-1,4,5-trisphosphate receptor. Importantly, store-independent Ca2+ entry through Orai compensates for reduced SOCE in the Drosophila flight circuit. Moreover, overexpression of Septin 7 reduces both SOCE and flight duration, supporting its role as a negative regulator of Orai channel function in vivo. Septin 7 levels in neurons can, therefore, alter neural circuit function by modulating Orai function and Ca2+ homeostasis. Orai channels are well known to mediate store-operated calcium entry. Here authors show that in neurons of the Drosophila flight circuit, Septin 7 acts as a negative regulator of Orai channels, surprisingly, by modulating store-independent calcium entry through Orai.
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Affiliation(s)
- Bipan Kumar Deb
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bellary Road, Bangalore 560065, India
| | - Trayambak Pathak
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bellary Road, Bangalore 560065, India.,Manipal University, Manipal, Karnataka 576104, India
| | - Gaiti Hasan
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bellary Road, Bangalore 560065, India
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112
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Abstract
Ca2+ entry into the cell via store-operated Ca2+ release-activated Ca2+ (CRAC) channels triggers diverse signaling cascades that affect cellular processes like cell growth, gene regulation, secretion, and cell death. These store-operated Ca2+ channels open after depletion of intracellular Ca2+ stores, and their main features are fully reconstituted by the two molecular key players: the stromal interaction molecule (STIM) and Orai. STIM represents an endoplasmic reticulum-located Ca2+ sensor, while Orai forms a highly Ca2+-selective ion channel in the plasma membrane. Functional as well as mutagenesis studies together with structural insights about STIM and Orai proteins provide a molecular picture of the interplay of these two key players in the CRAC signaling cascade. This review focuses on the main experimental advances in the understanding of the STIM1-Orai choreography, thereby establishing a portrait of key mechanistic steps in the CRAC channel signaling cascade. The focus is on the activation of the STIM proteins, the subsequent coupling of STIM1 to Orai1, and the consequent structural rearrangements that gate the Orai channels into the open state to allow Ca2+ permeation into the cell.
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Affiliation(s)
- Isabella Derler
- Institute of Biophysics, Johannes Kepler University of Linz, Linz, Austria; and
| | - Isaac Jardin
- Department of Physiology, University of Extremadura, Cáceres, Spain
| | - Christoph Romanin
- Institute of Biophysics, Johannes Kepler University of Linz, Linz, Austria; and
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113
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Shin DM, Son A, Park S, Kim MS, Ahuja M, Muallem S. The TRPCs, Orais and STIMs in ER/PM Junctions. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 898:47-66. [PMID: 27161224 DOI: 10.1007/978-3-319-26974-0_3] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The Ca(2+) second messenger is initiated at ER/PM junctions and propagates into the cell interior to convey the receptor information. The signal is maintained by Ca(2+) influx across the plasma membrane through the Orai and TRPC channels. These Ca(2+) influx channels form complexes at ER/PM junctions with the ER Ca(2+) sensor STIM1, which activates the channels. The function of STIM1 is modulated by other STIM isoforms like STIM1L, STIM2 and STIM2.1/STIM2β and by SARAF, which mediates the Ca(2+)-dependent inhibition of Orai channels. The ER/PM junctions are formed at membrane contact sites by tethering proteins that generate several types of ER/PM junctions, such as PI(4,5)P2-poor and PI(4,5)P2-rich domains. This chapter discusses several properties of the TRPC channels, the Orai channels and the STIMs, their key interacting proteins and how interaction of the STIMs with the channels gates their activity. The chapter closes by highlighting open questions and potential future directions in this field.
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Affiliation(s)
- Dong Min Shin
- Department of Oral Biology, BK 21 PLUS Project, Yonsei University College of Dentistry, Seoul, 120-752, South Korea.
| | - Aran Son
- Epithelial Signaling and Transport Section, Molecular Physiology and Therapeutics Branch, National Institute of Dental and Craniofacial Research, National Institute of Health, Bethesda, MD, 20892, USA
| | - Seonghee Park
- Department of Physiology, School of Medicine, EwhaWomans University, 911-1 Mok-6-dong, Yang Chun-gu, Seoul, 158-710, South Korea
| | - Min Seuk Kim
- Department of Oral Physiology, School of Dentistry, Wonkwang University, Iksan City, Jeonbuk, South Korea
| | - Malini Ahuja
- Epithelial Signaling and Transport Section, Molecular Physiology and Therapeutics Branch, National Institute of Dental and Craniofacial Research, National Institute of Health, Bethesda, MD, 20892, USA
| | - Shmuel Muallem
- Epithelial Signaling and Transport Section, Molecular Physiology and Therapeutics Branch, National Institute of Dental and Craniofacial Research, National Institute of Health, Bethesda, MD, 20892, USA.
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114
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The Calcium Entry-Calcium Refilling Coupling. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 898:333-52. [DOI: 10.1007/978-3-319-26974-0_14] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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115
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Frischauf I, Fahrner M, Jardín I, Romanin C. The STIM1: Orai Interaction. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 898:25-46. [PMID: 27161223 DOI: 10.1007/978-3-319-26974-0_2] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Ca(2+) influx via store-operated Ca(2+) release activated Ca(2+) (CRAC) channels represents a main signalling pathway for a variety of cell functions, including T-cell activation as well as mast-cell degranulation. Depletion of [Ca(2+)]ER results in activation of Ca(2+) channels within the plasmamembrane that mediate sustained Ca(2+) influx which is required for refilling Ca(2+) stores and down-stream Ca(2+) signalling. The CRAC channel is the best characterized store-operated channel (SOC) with well-defined electrophysiological properties. In recent years, the molecular components of the CRAC channel have been defined. The ER - located Ca(2+)-sensor, STIM1 and the Ca(2+)-selective ion pore, Orai1 in the membrane are sufficient to fully reconstitute CRAC currents. Stromal interaction molecule (STIM) 1 is localized in the ER, senses [Ca(2+)]ER and activates the CRAC channel upon store depletion by direct binding to Orai1 in the plasmamembrane. The identification of STIM1 and Orai1 and recently the structural resolution of both proteins by X-ray crystallography and nuclear magnetic resonance substantiated many findings from structure-function studies which has substantially improved the understanding of CRAC channel activation. Within this review, we summarize the functional and structural mechanisms of CRAC channel regulation, present a detailed overview of the STIM1/Orai1 signalling pathway where we focus on the critical domains mediating interactions and on the ion permeation pathway. We portray a mechanistic view of the steps in the dynamics of CRAC channel signalling ranging from STIM1 oligomerization over STIM1-Orai1 coupling to CRAC channel activation and permeation.
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Affiliation(s)
| | - Marc Fahrner
- Institute of Biophysics, University of Linz, Linz, Austria
| | - Isaac Jardín
- Department of Physiology, University of Extremadura, Cáceres, Spain
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116
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Ong HL, de Souza LB, Ambudkar IS. Role of TRPC Channels in Store-Operated Calcium Entry. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 898:87-109. [DOI: 10.1007/978-3-319-26974-0_5] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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117
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Raynal NJM, Lee JT, Wang Y, Beaudry A, Madireddi P, Garriga J, Malouf GG, Dumont S, Dettman EJ, Gharibyan V, Ahmed S, Chung W, Childers WE, Abou-Gharbia M, Henry RA, Andrews AJ, Jelinek J, Cui Y, Baylin SB, Gill DL, Issa JPJ. Targeting Calcium Signaling Induces Epigenetic Reactivation of Tumor Suppressor Genes in Cancer. Cancer Res 2015; 76:1494-505. [PMID: 26719529 DOI: 10.1158/0008-5472.can-14-2391] [Citation(s) in RCA: 76] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Accepted: 12/18/2015] [Indexed: 01/09/2023]
Abstract
Targeting epigenetic pathways is a promising approach for cancer therapy. Here, we report on the unexpected finding that targeting calcium signaling can reverse epigenetic silencing of tumor suppressor genes (TSG). In a screen for drugs that reactivate silenced gene expression in colon cancer cells, we found three classical epigenetic targeted drugs (DNA methylation and histone deacetylase inhibitors) and 11 other drugs that induced methylated and silenced CpG island promoters driving a reporter gene (GFP) as well as endogenous TSGs in multiple cancer cell lines. These newly identified drugs, most prominently cardiac glycosides, did not change DNA methylation locally or histone modifications globally. Instead, all 11 drugs altered calcium signaling and triggered calcium-calmodulin kinase (CamK) activity, leading to MeCP2 nuclear exclusion. Blocking CamK activity abolished gene reactivation and cancer cell killing by these drugs, showing that triggering calcium fluxes is an essential component of their epigenetic mechanism of action. Our data identify calcium signaling as a new pathway that can be targeted to reactivate TSGs in cancer.
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Affiliation(s)
- Noël J-M Raynal
- Fels Institute for Cancer Research and Molecular Biology, Temple University School of Medicine, Philadelphia, Pennsylvania. Département de pharmacologie, Université de Montréal and Sainte-Justine University Hospital Research Center, Montréal, Québec, Canada
| | - Justin T Lee
- Fels Institute for Cancer Research and Molecular Biology, Temple University School of Medicine, Philadelphia, Pennsylvania
| | - Youjun Wang
- Beijing Key Laboratory of Gene Resources and Molecular Development College of Life Sciences, Beijing Normal University, Beijing, P.R. China
| | - Annie Beaudry
- Département de pharmacologie, Université de Montréal and Sainte-Justine University Hospital Research Center, Montréal, Québec, Canada
| | - Priyanka Madireddi
- Fels Institute for Cancer Research and Molecular Biology, Temple University School of Medicine, Philadelphia, Pennsylvania
| | - Judith Garriga
- Fels Institute for Cancer Research and Molecular Biology, Temple University School of Medicine, Philadelphia, Pennsylvania
| | - Gabriel G Malouf
- Department of Leukemia, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Sarah Dumont
- Department of Leukemia, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Elisha J Dettman
- Department of Leukemia, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Vazganush Gharibyan
- Department of Leukemia, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Saira Ahmed
- Department of Leukemia, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Woonbok Chung
- Fels Institute for Cancer Research and Molecular Biology, Temple University School of Medicine, Philadelphia, Pennsylvania
| | - Wayne E Childers
- Moulder Center for Drug Discovery Research, Philadelphia, Pennsylvania
| | | | - Ryan A Henry
- Department of Cancer Biology, Fox Chase Cancer Center, Philadelphia, Pennsylvania
| | - Andrew J Andrews
- Department of Cancer Biology, Fox Chase Cancer Center, Philadelphia, Pennsylvania
| | - Jaroslav Jelinek
- Fels Institute for Cancer Research and Molecular Biology, Temple University School of Medicine, Philadelphia, Pennsylvania
| | - Ying Cui
- The Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Baltimore, Maryland
| | - Stephen B Baylin
- The Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Baltimore, Maryland
| | - Donald L Gill
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, The Milton S. Hershey Medical Center, Hershey, Pennsylvania
| | - Jean-Pierre J Issa
- Fels Institute for Cancer Research and Molecular Biology, Temple University School of Medicine, Philadelphia, Pennsylvania.
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118
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Abstract
Mechanotransduction, the conversion of physical forces into biochemical signals, is essential for various physiological processes such as the conscious sensations of touch and hearing, and the unconscious sensation of blood flow. Mechanically activated (MA) ion channels have been proposed as sensors of physical force, but the identity of these channels and an understanding of how mechanical force is transduced has remained elusive. A number of recent studies on previously known ion channels along with the identification of novel MA ion channels have greatly transformed our understanding of touch and hearing in both vertebrates and invertebrates. Here, we present an updated review of eukaryotic ion channel families that have been implicated in mechanotransduction processes and evaluate the qualifications of the candidate genes according to specified criteria. We then discuss the proposed gating models for MA ion channels and highlight recent structural studies of mechanosensitive potassium channels.
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Affiliation(s)
- Sanjeev S Ranade
- Howard Hughes Medical Institute, Molecular and Cellular Neuroscience, Dorris Neuroscience Center, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Ruhma Syeda
- Howard Hughes Medical Institute, Molecular and Cellular Neuroscience, Dorris Neuroscience Center, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Ardem Patapoutian
- Howard Hughes Medical Institute, Molecular and Cellular Neuroscience, Dorris Neuroscience Center, The Scripps Research Institute, La Jolla, CA 92037, USA.
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119
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Genetically targeted single-channel optical recording reveals multiple Orai1 gating states and oscillations in calcium influx. Proc Natl Acad Sci U S A 2015; 113:440-5. [PMID: 26712003 DOI: 10.1073/pnas.1523410113] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Orai1 comprises the pore-forming subunit of the Ca(2+) release-activated Ca(2+) (CRAC) channel. When bound and activated by stromal interacting molecule 1 (STIM1), an endoplasmic reticulum (ER)-resident calcium sensor, Orai1 channels possess high selectivity for calcium but extremely small conductance that has precluded direct recording of single-channel currents. We have developed an approach to visualize Orai1 activity by fusing Orai1 to fluorescent, genetically encoded calcium indicators (GECIs). The GECI-Orai1 probes reveal local Ca(2+) influx at STIM1-Orai1 puncta. By whole cell recording, these fusions are fully functional as CRAC channels. When GECI-Orai1 and the CRAC-activating domain (CAD) of STIM1 were coexpressed at low levels and imaged using a total internal reflectance fluorescence microscope, cells exhibited sporadic fluorescence transients the size of diffraction-limited spots and the brightness of a few activated GECI proteins. Transients typically rose rapidly and fell into two classes according to duration: briefer "flickers" lasting only a few hundred milliseconds, and longer "pulses" lasting one to several seconds. The size, intensity, trace shape, frequency, distribution, physiological characteristics, and association with CAD binding together demonstrate that GECI-Orai1 fluorescence transients correspond to single-channel Orai1 responses. Single Orai1 channels gated by CAD, and small Orai1 puncta gated by STIM1, exhibit repetitive fluctuations in single-channel output. CAD binding supports a role in open state maintenance and reveals a second phase of CAD/STIM1 binding after channel opening. These first recordings of single-channel Orai1 currents reveal unexpected dynamics, and when paired with CAD association, support multiple single-channel states.
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120
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Frischauf I, Zayats V, Deix M, Hochreiter A, Jardin I, Muik M, Lackner B, Svobodová B, Pammer T, Litviňuková M, Sridhar AA, Derler I, Bogeski I, Romanin C, Ettrich RH, Schindl R. A calcium-accumulating region, CAR, in the channel Orai1 enhances Ca(2+) permeation and SOCE-induced gene transcription. Sci Signal 2015; 8:ra131. [PMID: 26696631 DOI: 10.1126/scisignal.aab1901] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The Ca(2+) release-activated Ca(2+) channel mediates Ca(2+) influx in a plethora of cell types, thereby controlling diverse cellular functions. The channel complex is composed of stromal interaction molecule 1 (STIM1), an endoplasmic reticulum Ca(2+)-sensing protein, and Orai1, a plasma membrane Ca(2+) channel. Channels composed of STIM1 and Orai1 mediate Ca(2+) influx even at low extracellular Ca(2+) concentrations. We investigated whether the activity of Orai1 adapted to different environmental Ca(2+) concentrations. We used homology modeling and molecular dynamics simulations to predict the presence of an extracellular Ca(2+)-accumulating region (CAR) at the pore entrance of Orai1. Furthermore, simulations of Orai1 proteins with mutations in CAR, along with live-cell experiments, or simulations and electrophysiological recordings of the channel with transient, electrostatic loop3 interacting with loop1 (the site of CAR) determined that CAR enhanced Ca(2+) permeation most efficiently at low external Ca(2+) concentrations. Consistent with these results, cells expressing Orai1 CAR mutants exhibited impaired gene expression stimulated by the Ca(2+)-activated transcription factor nuclear factor of activated T cells (NFAT). We propose that the Orai1 channel architecture with a close proximity of CAR to the selectivity filter, which enables Ca(2+)-selective ion permeation, enhances the local extracellular Ca(2+) concentration to maintain Ca(2+)-dependent gene regulation even in environments with relatively low Ca(2+)concentrations.
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Affiliation(s)
- Irene Frischauf
- Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, Gruberstrasse 40, 4020 Linz, Austria
| | - Vasilina Zayats
- Center for Nanobiology and Structural Biology, Institute of Microbiology, Academy of Sciences of the Czech Republic, Zamek 136, CZ-373 33, Nove Hrady, Czech Republic.,Faculty of Sciences, University of South Bohemia, Zamek 136, CZ-373 33, Nove Hrady, Czech Republic
| | - Michael Deix
- Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, Gruberstrasse 40, 4020 Linz, Austria
| | - Anna Hochreiter
- Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, Gruberstrasse 40, 4020 Linz, Austria.,Institute for Experimental and Clinical Cell Therapy, Paracelsus Medical University, A-5020 Salzburg, Austria
| | - Isaac Jardin
- Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, Gruberstrasse 40, 4020 Linz, Austria
| | - Martin Muik
- Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, Gruberstrasse 40, 4020 Linz, Austria
| | - Barbara Lackner
- Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, Gruberstrasse 40, 4020 Linz, Austria
| | - Barbora Svobodová
- Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, Gruberstrasse 40, 4020 Linz, Austria.,Institute for Biophysics of Medical University Graz, A-8010, Graz, Austria
| | - Teresa Pammer
- Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, Gruberstrasse 40, 4020 Linz, Austria
| | - Monika Litviňuková
- Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, Gruberstrasse 40, 4020 Linz, Austria
| | - Amrutha Arumbakam Sridhar
- Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, Gruberstrasse 40, 4020 Linz, Austria
| | - Isabella Derler
- Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, Gruberstrasse 40, 4020 Linz, Austria
| | - Ivan Bogeski
- Department of Biophysics, School of Medicine, University of Saarland, D-66421 Homburg, Germany
| | - Christoph Romanin
- Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, Gruberstrasse 40, 4020 Linz, Austria
| | - Rüdiger H Ettrich
- Center for Nanobiology and Structural Biology, Institute of Microbiology, Academy of Sciences of the Czech Republic, Zamek 136, CZ-373 33, Nove Hrady, Czech Republic.,Faculty of Sciences, University of South Bohemia, Zamek 136, CZ-373 33, Nove Hrady, Czech Republic
| | - Rainer Schindl
- Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, Gruberstrasse 40, 4020 Linz, Austria
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121
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Palty R, Isacoff EY. Cooperative Binding of Stromal Interaction Molecule 1 (STIM1) to the N and C Termini of Calcium Release-activated Calcium Modulator 1 (Orai1). J Biol Chem 2015; 291:334-41. [PMID: 26546674 DOI: 10.1074/jbc.m115.685289] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Indexed: 11/06/2022] Open
Abstract
Calcium flux through store-operated calcium entry is a central regulator of intracellular calcium signaling. The two key components of the store-operated calcium release-activated calcium channel are the Ca(2+)-sensing protein stromal interaction molecule 1 (STIM1) and the channel pore-forming protein Orai1. During store-operated calcium entry activation, calcium depletion from the endoplasmic reticulum triggers a series of conformational changes in STIM1 that unmask a minimal Orai1-activating domain (CRAC activation region (CAD)). To gate Orai1 channels, the exposed STIM1-activating domain binds to two sites in Orai1, one in the N terminus and one in the C terminus. Whether the two sites operate as distinct binding domains or cooperate in CAD binding is unknown. In this study, we show that the N and C-terminal domains of Orai1 synergistically contribute to the interaction with STIM1 and couple STIM1 binding with channel gating and modulation of ion selectivity.
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Affiliation(s)
- Raz Palty
- From the Department of Molecular and Cell Biology and
| | - Ehud Y Isacoff
- From the Department of Molecular and Cell Biology and Helen Wills Neuroscience Institute, University of California Berkeley, Berkeley, California 94720 and the Physical Bioscience Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720
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122
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Amcheslavsky A, Wood ML, Yeromin AV, Parker I, Freites JA, Tobias DJ, Cahalan MD. Molecular biophysics of Orai store-operated Ca2+ channels. Biophys J 2015; 108:237-46. [PMID: 25606672 DOI: 10.1016/j.bpj.2014.11.3473] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Revised: 11/24/2014] [Accepted: 11/26/2014] [Indexed: 12/12/2022] Open
Abstract
Upon endoplasmic reticulum Ca(2+) store depletion, Orai channels in the plasma membrane are activated directly by endoplasmic reticulum-resident STIM proteins to generate the Ca(2+)-selective, Ca(2+) release-activated Ca(2+) (CRAC) current. After the molecular identification of Orai, a plethora of functional and biochemical studies sought to compare Orai homologs, determine their stoichiometry, identify structural domains responsible for the biophysical fingerprint of the CRAC current, identify the physiological functions, and investigate Orai homologs as potential therapeutic targets. Subsequently, the solved crystal structure of Drosophila Orai (dOrai) substantiated many findings from structure-function studies, but also revealed an unexpected hexameric structure. In this review, we explore Orai channels as elucidated by functional and biochemical studies, analyze the dOrai crystal structure and its implications for Orai channel function, and present newly available information from molecular dynamics simulations that shed light on Orai channel gating and permeation.
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Affiliation(s)
- Anna Amcheslavsky
- Department of Physiology and Biophysics, University of California at Irvine, Irvine, California
| | - Mona L Wood
- Department of Chemistry, University of California at Irvine, Irvine, California
| | - Andriy V Yeromin
- Department of Physiology and Biophysics, University of California at Irvine, Irvine, California
| | - Ian Parker
- Department of Physiology and Biophysics, University of California at Irvine, Irvine, California; Department of Neurobiology and Behavior, University of California at Irvine, Irvine, California
| | - J Alfredo Freites
- Department of Chemistry, University of California at Irvine, Irvine, California
| | - Douglas J Tobias
- Department of Chemistry, University of California at Irvine, Irvine, California
| | - Michael D Cahalan
- Department of Physiology and Biophysics, University of California at Irvine, Irvine, California; Institute for Immunology, University of California at Irvine, Irvine, California.
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123
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Abstract
Store-operated calcium channels (SOCs) are a major pathway for calcium signaling in virtually all metozoan cells and serve a wide variety of functions ranging from gene expression, motility, and secretion to tissue and organ development and the immune response. SOCs are activated by the depletion of Ca(2+) from the endoplasmic reticulum (ER), triggered physiologically through stimulation of a diverse set of surface receptors. Over 15 years after the first characterization of SOCs through electrophysiology, the identification of the STIM proteins as ER Ca(2+) sensors and the Orai proteins as store-operated channels has enabled rapid progress in understanding the unique mechanism of store-operate calcium entry (SOCE). Depletion of Ca(2+) from the ER causes STIM to accumulate at ER-plasma membrane (PM) junctions where it traps and activates Orai channels diffusing in the closely apposed PM. Mutagenesis studies combined with recent structural insights about STIM and Orai proteins are now beginning to reveal the molecular underpinnings of these choreographic events. This review describes the major experimental advances underlying our current understanding of how ER Ca(2+) depletion is coupled to the activation of SOCs. Particular emphasis is placed on the molecular mechanisms of STIM and Orai activation, Orai channel properties, modulation of STIM and Orai function, pharmacological inhibitors of SOCE, and the functions of STIM and Orai in physiology and disease.
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Affiliation(s)
- Murali Prakriya
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois; and Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, California
| | - Richard S Lewis
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois; and Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, California
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124
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Optogenetic control of endogenous Ca2+ channels in vivo. Nat Biotechnol 2015; 33:1092-6. [DOI: 10.1038/nbt.3350] [Citation(s) in RCA: 118] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Accepted: 08/20/2015] [Indexed: 01/18/2023]
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125
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Discovery and structural optimization of 1-phenyl-3-(1-phenylethyl)urea derivatives as novel inhibitors of CRAC channel. Acta Pharmacol Sin 2015; 36:1137-44. [PMID: 26256403 DOI: 10.1038/aps.2015.52] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2015] [Accepted: 04/27/2015] [Indexed: 02/05/2023] Open
Abstract
AIM Ca(2+)-release-activated Ca(2+) (CRAC) channel, a subfamily of store-operated channels, is formed by calcium release-activated calcium modulator 1 (ORAI1), and gated by stromal interaction molecule 1 (STIM1). CRAC channel may be a novel target for the treatment of immune disorders and allergy. The aim of this study was to identify novel small molecule CRAC channel inhibitors. METHODS HEK293 cells stably co-expressing both ORAI1 and STIM1 were used for high-throughput screening. A hit, 1-phenyl-3-(1-phenylethyl)urea, was identified that inhibited CRAC channels by targeting ORAI1. Five series of its derivatives were designed and synthesized, and their primary structure-activity relationships (SARs) were analyzed. All derivatives were assessed for their effects on Ca(2+) influx through CRAC channels on HEK293 cells, cytotoxicity in Jurkat cells, and IL-2 production in Jurkat cells expressing ORAI1-SS-eGFP. RESULTS A total of 19 hits were discovered in libraries containing 32 000 compounds using the high-throughput screening. 1-Phenyl-3-(1-phenylethyl)urea inhibited Ca(2+) influx with IC50 of 3.25±0.17 μmol/L. SAR study on its derivatives showed that the alkyl substituent on the α-position of the left-side benzylic amine (R1) was essential for Ca(2+) influx inhibition and that the S-configuration was better than the R-configuration. The derivatives in which the right-side R3 was substituted by an electron-donating group showed more potent inhibitory activity than those that were substituted by electron-withdrawing groups. Furthermore, the free N-H of urea was not necessary to maintain the high potency of Ca(2+) influx inhibition. The N,N'-disubstituted or N'-substituted derivatives showed relatively low cytotoxicity but maintained the ability to inhibit IL-2 production. Among them, compound 5b showed an improved inhibition of IL-2 production and low cytotoxicity. CONCLUSION 1-Phenyl-3-(1-phenylethyl)urea is a novel CRAC channel inhibitor that specifically targets ORAI1. This study provides a new chemical scaffold for design and development of CRAC channel inhibitors with improved Ca(2+) influx inhibition, immune inhibition and low cytotoxicity.
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126
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Jairaman A, Yamashita M, Schleimer RP, Prakriya M. Store-Operated Ca2+ Release-Activated Ca2+ Channels Regulate PAR2-Activated Ca2+ Signaling and Cytokine Production in Airway Epithelial Cells. THE JOURNAL OF IMMUNOLOGY 2015; 195:2122-33. [PMID: 26238490 DOI: 10.4049/jimmunol.1500396] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Accepted: 06/30/2015] [Indexed: 01/11/2023]
Abstract
The G-protein-coupled protease-activated receptor 2 (PAR2) plays an important role in the pathogenesis of various inflammatory and auto-immune disorders. In airway epithelial cells (AECs), stimulation of PAR2 by allergens and proteases triggers the release of a host of inflammatory mediators to regulate bronchomotor tone and immune cell recruitment. Activation of PAR2 turns on several cell signaling pathways of which the mobilization of cytosolic Ca(2+) is likely a critical but poorly understood event. In this study, we show that Ca(2+) release-activated Ca(2+) (CRAC) channels encoded by stromal interaction molecule 1 and Orai1 are a major route of Ca(2+) entry in primary human AECs and drive the Ca(2+) elevations seen in response to PAR2 activation. Activation of CRAC channels induces the production of several key inflammatory mediators from AECs including thymic stromal lymphopoietin, IL-6, and PGE2, in part through stimulation of gene expression via nuclear factor of activated T cells (NFAT). Furthermore, PAR2 stimulation induces the production of many key inflammatory mediators including PGE2, IL-6, IL-8, and GM-CSF in a CRAC channel-dependent manner. These findings indicate that CRAC channels are the primary mechanism for Ca(2+) influx in AECs and a vital checkpoint for the induction of PAR2-induced proinflammatory cytokines.
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Affiliation(s)
- Amit Jairaman
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611; and
| | - Megumi Yamashita
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611; and
| | - Robert P Schleimer
- Division of Allergy/Immunology, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL 60611
| | - Murali Prakriya
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611; and
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127
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Store-operated calcium entry: Mechanisms and modulation. Biochem Biophys Res Commun 2015; 460:40-9. [PMID: 25998732 DOI: 10.1016/j.bbrc.2015.02.110] [Citation(s) in RCA: 152] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Accepted: 02/20/2015] [Indexed: 11/22/2022]
Abstract
Store-operated calcium entry is a central mechanism in cellular calcium signalling and in maintaining cellular calcium balance. This review traces the history of research on store-operated calcium entry, the discovery of STIM and ORAI as central players in calcium entry, and the role of STIM and ORAI in biology and human disease. It describes current knowledge of the basic mechanism of STIM-ORAI signalling and of the varied mechanisms by which STIM-ORAI signalling can be modulated.
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128
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Samanta K, Kar P, Mirams GR, Parekh AB. Ca(2+) Channel Re-localization to Plasma-Membrane Microdomains Strengthens Activation of Ca(2+)-Dependent Nuclear Gene Expression. Cell Rep 2015; 12:203-16. [PMID: 26146085 PMCID: PMC4521080 DOI: 10.1016/j.celrep.2015.06.018] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2014] [Revised: 05/15/2015] [Accepted: 06/04/2015] [Indexed: 12/25/2022] Open
Abstract
In polarized cells or cells with complex geometry, clustering of plasma-membrane (PM) ion channels is an effective mechanism for eliciting spatially restricted signals. However, channel clustering is also seen in cells with relatively simple topology, suggesting it fulfills a more fundamental role in cell biology than simply orchestrating compartmentalized responses. Here, we have compared the ability of store-operated Ca(2+) release-activated Ca(2+) (CRAC) channels confined to PM microdomains with a similar number of dispersed CRAC channels to activate transcription factors, which subsequently increase nuclear gene expression. For similar levels of channel activity, we find that channel confinement is considerably more effective in stimulating gene expression. Our results identify a long-range signaling advantage to the tight evolutionary conservation of channel clustering and reveal that CRAC channel aggregation increases the strength, fidelity, and reliability of the general process of excitation-transcription coupling.
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Affiliation(s)
- Krishna Samanta
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford OX1 3PT, UK
| | - Pulak Kar
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford OX1 3PT, UK
| | - Gary R Mirams
- Department of Computer Science, University of Oxford, Oxford OX1 3QD, UK
| | - Anant B Parekh
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford OX1 3PT, UK.
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129
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Critical role for Orai1 C-terminal domain and TM4 in CRAC channel gating. Cell Res 2015; 25:963-80. [PMID: 26138675 DOI: 10.1038/cr.2015.80] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Revised: 03/30/2015] [Accepted: 05/22/2015] [Indexed: 01/12/2023] Open
Abstract
Calcium flux through store-operated calcium entry is a major regulator of intracellular calcium homeostasis and various calcium signaling pathways. Two key components of the store-operated calcium release-activated calcium channel are the Ca(2+)-sensing protein stromal interaction molecule 1 (STIM1) and the channel pore-forming protein Orai1. Following calcium depletion from the endoplasmic reticulum, STIM1 undergoes conformational changes that unmask an Orai1-activating domain called CAD. CAD binds to two sites in Orai1, one in the N terminal and one in the C terminal. Most previous studies suggested that gating is initiated by STIM1 binding at the Orai1 N-terminal site, just proximal to the TM1 pore-lining segment, and that binding at the C terminal simply anchors STIM1 within reach of the N terminal. However, a recent study had challenged this view and suggested that the Orai1 C-terminal region is more than a simple STIM1-anchoring site. In this study, we establish that the Orai1 C-terminal domain plays a direct role in gating. We identify a linker region between TM4 and the C-terminal STIM1-binding segment of Orai1 as a key determinant that couples STIM1 binding to gating. We further find that Proline 245 in TM4 of Orai1 is essential for stabilizing the closed state of the channel. Taken together with previous studies, our results suggest a dual-trigger mechanism of Orai1 activation in which binding of STIM1 at the N- and C-terminal domains of Orai1 induces rearrangements in proximal membrane segments to open the channel.
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130
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Hodeify R, Selvaraj S, Wen J, Arredouani A, Hubrack S, Dib M, Al-Thani SN, McGraw T, Machaca K. A STIM1-dependent 'trafficking trap' mechanism regulates Orai1 plasma membrane residence and Ca²⁺ influx levels. J Cell Sci 2015; 128:3143-54. [PMID: 26116575 DOI: 10.1242/jcs.172320] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2015] [Accepted: 06/23/2015] [Indexed: 01/21/2023] Open
Abstract
The key proteins mediating store-operated Ca(2+) entry (SOCE) are the endoplasmic reticulum (ER) Ca(2+) sensor STIM1 and the plasma membrane Ca(2+)-selective channel Orai1. Here, we quantitatively dissect Orai1 trafficking dynamics and show that Orai1 recycles rapidly at the plasma membrane (Kex≃0.1 min(-1)), with ∼40% of the total Orai1 pool localizing to the plasma membrane at steady state. A subset of intracellular Orai1 localizes to a sub-plasmalemal compartment. Store depletion is coupled to Orai1 plasma membrane enrichment in a STIM1-dependent fashion. This is due to trapping of Orai1 into cortical ER STIM1 clusters, leading to its removal from the recycling pool and enrichment at the plasma membrane. Interestingly, upon high STIM1 expression, Orai1 is trapped into STIM1 clusters intracellularly, thus preventing its plasma membrane enrichment following store depletion. Consistent with this, STIM1 knockdown prevents trapping of excess Orai1 into limiting STIM1 clusters in the cortical ER. SOCE-dependent Ca(2+) influx shows a similar biphasic dependence on the Orai1:STIM1 ratio. Therefore, a STIM1-dependent Orai1 'trafficking trap' mechanism controls Orai1 plasma membrane enrichment and SOCE levels, thus modulating the SOCE 'bandwidth' for downstream signaling.
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Affiliation(s)
- Rawad Hodeify
- Department of Physiology & Biophysics, Weill Cornell Medical College in Qatar, PO Box 24144, Qatar
| | - Senthil Selvaraj
- Department of Physiology & Biophysics, Weill Cornell Medical College in Qatar, PO Box 24144, Qatar
| | - Jennifer Wen
- Department of Biochemistry, Weill Cornell Medical College, New York, 10021 USA
| | - Abdelilah Arredouani
- Department of Physiology & Biophysics, Weill Cornell Medical College in Qatar, PO Box 24144, Qatar
| | - Satanay Hubrack
- Department of Physiology & Biophysics, Weill Cornell Medical College in Qatar, PO Box 24144, Qatar
| | - Maya Dib
- Department of Physiology & Biophysics, Weill Cornell Medical College in Qatar, PO Box 24144, Qatar
| | - Sara N Al-Thani
- Department of Physiology & Biophysics, Weill Cornell Medical College in Qatar, PO Box 24144, Qatar
| | - Timothy McGraw
- Department of Biochemistry, Weill Cornell Medical College, New York, 10021 USA
| | - Khaled Machaca
- Department of Physiology & Biophysics, Weill Cornell Medical College in Qatar, PO Box 24144, Qatar
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131
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Rana A, Yen M, Sadaghiani AM, Malmersjö S, Park CY, Dolmetsch RE, Lewis RS. Alternative splicing converts STIM2 from an activator to an inhibitor of store-operated calcium channels. J Cell Biol 2015; 209:653-69. [PMID: 26033257 PMCID: PMC4460148 DOI: 10.1083/jcb.201412060] [Citation(s) in RCA: 88] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Accepted: 04/27/2015] [Indexed: 11/22/2022] Open
Abstract
STIM2β is a novel STIM2 splice isoform that inhibits Orai channels. Store-operated calcium entry (SOCE) regulates a wide variety of essential cellular functions. SOCE is mediated by STIM1 and STIM2, which sense depletion of ER Ca2+ stores and activate Orai channels in the plasma membrane. Although the amplitude and dynamics of SOCE are considered important determinants of Ca2+-dependent responses, the underlying modulatory mechanisms are unclear. In this paper, we identify STIM2β, a highly conserved alternatively spliced isoform of STIM2, which, in contrast to all known STIM isoforms, is a potent inhibitor of SOCE. Although STIM2β does not by itself strongly bind Orai1, it is recruited to Orai1 channels by forming heterodimers with other STIM isoforms. Analysis of STIM2β mutants and Orai1-STIM2β chimeras suggested that it actively inhibits SOCE through a sequence-specific allosteric interaction with Orai1. Our results reveal a previously unrecognized functional flexibility in the STIM protein family by which alternative splicing creates negative and positive regulators of SOCE to shape the amplitude and dynamics of Ca2+ signals.
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Affiliation(s)
- Anshul Rana
- Graduate Program in Biochemistry, Stanford University School of Medicine, Stanford, CA 94305 Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305
| | - Michelle Yen
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305 Graduate Program in Immunology, Stanford University School of Medicine, Stanford, CA 94305
| | - Amir Masoud Sadaghiani
- Department of Neurobiology, Stanford University School of Medicine, Stanford, CA 94305 Novartis Institutes for Biomedical Research, Boston, MA 02139
| | - Seth Malmersjö
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA 94305
| | - Chan Young Park
- Department of Biological Sciences, Ulsan National Institute of Science and Technology, Ulsan 689-798, South Korea
| | - Ricardo E Dolmetsch
- Department of Neurobiology, Stanford University School of Medicine, Stanford, CA 94305 Novartis Institutes for Biomedical Research, Boston, MA 02139
| | - Richard S Lewis
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305
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132
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Shanmughapriya S, Rajan S, Hoffman NE, Zhang X, Guo S, Kolesar JE, Hines KJ, Ragheb J, Jog NR, Caricchio R, Baba Y, Zhou Y, Kaufman BA, Cheung JY, Kurosaki T, Gill DL, Madesh M. Ca2+ signals regulate mitochondrial metabolism by stimulating CREB-mediated expression of the mitochondrial Ca2+ uniporter gene MCU. Sci Signal 2015; 8:ra23. [PMID: 25737585 DOI: 10.1126/scisignal.2005673] [Citation(s) in RCA: 104] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Cytosolic Ca2+ signals, generated through the coordinated translocation of Ca2+ across the plasma membrane (PM) and endoplasmic reticulum (ER) membrane, mediate diverse cellular responses. Mitochondrial Ca2+ is important for mitochondrial function, and when cytosolic Ca2+ concentration becomes too high, mitochondria function as cellular Ca2+ sinks. By measuring mitochondrial Ca2+ currents, we found that mitochondrial Ca2+ uptake was reduced in chicken DT40 B lymphocytes lacking either the ER-localized inositol trisphosphate receptor (IP3R), which releases Ca2+ from the ER, or Orai1 or STIM1, components of the PM-localized Ca2+ -permeable channel complex that mediates store-operated calcium entry (SOCE) in response to depletion of ER Ca2+ stores. The abundance of MCU, the pore-forming subunit of the mitochondrial Ca2+ uniporter, was reduced in cells deficient in IP3R, STIM1, or Orai1. Chromatin immunoprecipitation and promoter reporter analyses revealed that the Ca2+ -regulated transcription factor CREB (cyclic adenosine monophosphate response element-binding protein) directly bound the MCU promoter and stimulated expression. Lymphocytes deficient in IP3R, STIM1, or Orai1 exhibited altered mitochondrial metabolism, indicating that Ca2+ released from the ER and SOCE-mediated signals modulates mitochondrial function. Thus, our results showed that a transcriptional regulatory circuit involving Ca2+ -dependent activation of CREB controls the Ca2+ uptake capability of mitochondria and hence regulates mitochondrial metabolism.
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Affiliation(s)
- Santhanam Shanmughapriya
- Department of Biochemistry, Temple University, Philadelphia, PA 19140, USA. Center for Translational Medicine, Temple University, Philadelphia, PA 19140, USA
| | - Sudarsan Rajan
- Department of Biochemistry, Temple University, Philadelphia, PA 19140, USA. Center for Translational Medicine, Temple University, Philadelphia, PA 19140, USA
| | - Nicholas E Hoffman
- Department of Biochemistry, Temple University, Philadelphia, PA 19140, USA. Center for Translational Medicine, Temple University, Philadelphia, PA 19140, USA
| | - Xueqian Zhang
- Center for Translational Medicine, Temple University, Philadelphia, PA 19140, USA
| | - Shuchi Guo
- Department of Biochemistry, Temple University, Philadelphia, PA 19140, USA. Center for Translational Medicine, Temple University, Philadelphia, PA 19140, USA
| | - Jill E Kolesar
- Department of Animal Biology, University of Pennsylvania School of Veterinary Medicine, Philadelphia, PA 19104, USA
| | - Kevin J Hines
- Department of Biochemistry, Temple University, Philadelphia, PA 19140, USA. Center for Translational Medicine, Temple University, Philadelphia, PA 19140, USA
| | - Jonathan Ragheb
- Department of Biochemistry, Temple University, Philadelphia, PA 19140, USA. Center for Translational Medicine, Temple University, Philadelphia, PA 19140, USA
| | - Neelakshi R Jog
- Department of Medicine, Temple University, Philadelphia, PA 19140, USA
| | - Roberto Caricchio
- Department of Medicine, Temple University, Philadelphia, PA 19140, USA
| | - Yoshihiro Baba
- Laboratory of Lymphocyte Differentiation, World Premiere International Immunology Frontier Research Center, Osaka University, Osaka 565-0871, Japan
| | - Yandong Zhou
- Department of Cellular and Molecular Physiology, Penn State University College of Medicine, Hershey, PA 17033, USA
| | - Brett A Kaufman
- Department of Animal Biology, University of Pennsylvania School of Veterinary Medicine, Philadelphia, PA 19104, USA
| | - Joseph Y Cheung
- Center for Translational Medicine, Temple University, Philadelphia, PA 19140, USA
| | - Tomohiro Kurosaki
- Laboratory of Lymphocyte Differentiation, World Premiere International Immunology Frontier Research Center, Osaka University, Osaka 565-0871, Japan
| | - Donald L Gill
- Department of Cellular and Molecular Physiology, Penn State University College of Medicine, Hershey, PA 17033, USA.
| | - Muniswamy Madesh
- Department of Biochemistry, Temple University, Philadelphia, PA 19140, USA. Center for Translational Medicine, Temple University, Philadelphia, PA 19140, USA.
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133
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Hendron E, Wang X, Zhou Y, Cai X, Goto JI, Mikoshiba K, Baba Y, Kurosaki T, Wang Y, Gill DL. Potent functional uncoupling between STIM1 and Orai1 by dimeric 2-aminodiphenyl borinate analogs. Cell Calcium 2014; 56:482-92. [PMID: 25459299 DOI: 10.1016/j.ceca.2014.10.005] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2014] [Revised: 10/10/2014] [Accepted: 10/14/2014] [Indexed: 12/21/2022]
Abstract
The coupling of ER Ca(2+)-sensing STIM proteins and PM Orai Ca(2+) entry channels generates "store-operated" Ca(2+) signals crucial in controlling responses in many cell types. The dimeric derivative of 2-aminoethoxydiphenyl borinate (2-APB), DPB162-AE, blocks functional coupling between STIM1 and Orai1 with an IC50 (200 nM) 100-fold lower than 2-APB. Unlike 2-APB, DPB162-AE does not affect L-type or TRPC channels or Ca(2+) pumps at maximal STIM1-Orai1 blocking levels. DPB162-AE blocks STIM1-induced Orai1 or Orai2, but does not block Orai3 or STIM2-mediated effects. We narrowed the DPB162-AE site of action to the STIM-Orai activating region (SOAR) of STIM1. DPB162-AE does not prevent the SOAR-Orai1 interaction but potently blocks SOAR-mediated Orai1 channel activation, yet its action is not as an Orai1 channel pore blocker. Using the SOAR-F394H mutant which prevents both physical and functional coupling to Orai1, we reveal DPB162-AE rapidly restores SOAR-Orai binding but only slowly restores Orai1 channel-mediated Ca(2+) entry. With the same SOAR mutant, 2-APB induces rapid physical and functional coupling to Orai1, but channel activation is transient. We infer that the actions of both 2-APB and DPB162-AE are directed toward the STIM1-Orai1 coupling interface. Compared to 2-APB, DPB162-AE is a much more potent and specific STIM1/Orai1 functional uncoupler. DPB162-AE provides an important pharmacological tool and a useful mechanistic probe for the function and coupling between STIM1 and Orai1 channels.
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Affiliation(s)
- Eunan Hendron
- Department of Biochemistry, Temple University School of Medicine, Philadelphia, PA 19140, United States
| | - Xizhuo Wang
- Department of Biochemistry, Temple University School of Medicine, Philadelphia, PA 19140, United States; Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, PA 17033, United States
| | - Yandong Zhou
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, PA 17033, United States
| | - Xiangyu Cai
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, PA 17033, United States
| | - Jun-ichi Goto
- Department of Physiology, Yamagata University School of Medicine, Yamagata 990-9585, Japan
| | - Katsuhiko Mikoshiba
- Laboratory for Developmental Neurobiology, RIKEN Brain Science Institute, Saitama 351-0198, Japan
| | - Yoshihiro Baba
- Laboratory for Lymphocyte Differentiation, WPI Immunology Frontier Research Center, Osaka University, Suita, Osaka 565-0871, Japan; Laboratory for Lymphocyte Differentiation, RIKEN Center for Integrative Medical Sciences, Yokohama, Kanagawa 230-0045, Japan
| | - Tomohiro Kurosaki
- Laboratory for Lymphocyte Differentiation, WPI Immunology Frontier Research Center, Osaka University, Suita, Osaka 565-0871, Japan; Laboratory for Lymphocyte Differentiation, RIKEN Center for Integrative Medical Sciences, Yokohama, Kanagawa 230-0045, Japan
| | - Youjun Wang
- Beijing Key Laboratory of Gene Resources and Molecular Development College of Life Sciences, Beijing Normal University, Beijing 100875, PR China.
| | - Donald L Gill
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, PA 17033, United States.
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134
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Gudlur A, Quintana A, Zhou Y, Hirve N, Mahapatra S, Hogan PG. STIM1 triggers a gating rearrangement at the extracellular mouth of the ORAI1 channel. Nat Commun 2014; 5:5164. [PMID: 25296861 PMCID: PMC4376667 DOI: 10.1038/ncomms6164] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2014] [Accepted: 09/04/2014] [Indexed: 01/28/2023] Open
Abstract
The ER-resident regulatory protein STIM1 triggers store-operated Ca2+ entry by direct interaction with the plasma membrane Ca2+ channel ORAI1. The mechanism of channel gating remains undefined. Here we establish that STIM1 gates the purified recombinant ORAI1 channel in vitro, and use Tb3+ luminescence and, separately, disulfide crosslinking to probe movements of the pore-lining helices. We show that interaction of STIM1 with the cytoplasmic face of the human ORAI1 channel elicits a conformational change near the external entrance to the pore, detectable at the pore Ca2+-binding residue E106 and the adjacent pore-lining residue V102. We demonstrate that a short nonpolar segment of the pore including V102 forms a barrier to ion flux in the closed channel, implicating the STIM1-dependent movement in channel gating. Our data explain the close coupling between ORAI1 channel gating and ion selectivity, and open a new avenue to dissect the gating, modulation, and inactivation of ORAI-family channels.
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Affiliation(s)
- Aparna Gudlur
- Division of Signalling and Gene Expression, La Jolla Institute for Allergy and Immunology, La Jolla, California 92037, USA
| | - Ariel Quintana
- Division of Signalling and Gene Expression, La Jolla Institute for Allergy and Immunology, La Jolla, California 92037, USA
| | - Yubin Zhou
- Division of Signalling and Gene Expression, La Jolla Institute for Allergy and Immunology, La Jolla, California 92037, USA
| | - Nupura Hirve
- Division of Signalling and Gene Expression, La Jolla Institute for Allergy and Immunology, La Jolla, California 92037, USA
| | - Sahasransu Mahapatra
- Division of Signalling and Gene Expression, La Jolla Institute for Allergy and Immunology, La Jolla, California 92037, USA
| | - Patrick G Hogan
- Division of Signalling and Gene Expression, La Jolla Institute for Allergy and Immunology, La Jolla, California 92037, USA
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135
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Shim AHR, Tirado-Lee L, Prakriya M. Structural and functional mechanisms of CRAC channel regulation. J Mol Biol 2014; 427:77-93. [PMID: 25284754 DOI: 10.1016/j.jmb.2014.09.021] [Citation(s) in RCA: 75] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2014] [Revised: 09/18/2014] [Accepted: 09/25/2014] [Indexed: 11/29/2022]
Abstract
In many animal cells, stimulation of cell surface receptors coupled to G proteins or tyrosine kinases mobilizes Ca(2+) influx through store-operated Ca(2+)-release-activated Ca(2+) (CRAC) channels. The ensuing Ca(2+) entry regulates a wide variety of effector cell responses including transcription, motility, and proliferation. The physiological importance of CRAC channels for human health is underscored by studies indicating that mutations in CRAC channel genes produce a spectrum of devastating diseases including chronic inflammation, muscle weakness, and a severe combined immunodeficiency syndrome. Moreover, from a basic science perspective, CRAC channels exhibit a unique biophysical fingerprint characterized by exquisite Ca(2+) selectivity, store-operated gating, and distinct pore properties and therefore serve as fascinating model ion channels for understanding the biophysical mechanisms of Ca(2+) selectivity and channel opening. Studies in the last two decades have revealed the cellular and molecular choreography of the CRAC channel activation process, and it is now established that opening of CRAC channels is governed through direct interactions between the pore-forming Orai proteins and the endoplasmic reticulum Ca(2+) sensors STIM1 and STIM2. In this review, we summarize the functional and structural mechanisms of CRAC channel regulation, focusing on recent advances in our understanding of the conformational and structural dynamics of CRAC channel gating.
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Affiliation(s)
- Ann Hye-Ryong Shim
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Leidamarie Tirado-Lee
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Murali Prakriya
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA.
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136
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Sadaghiani A, Lee S, Odegaard J, Leveson-Gower D, McPherson O, Novick P, Kim M, Koehler A, Negrin R, Dolmetsch R, Park C. Identification of Orai1 Channel Inhibitors by Using Minimal Functional Domains to Screen Small Molecule Microarrays. ACTA ACUST UNITED AC 2014; 21:1278-1292. [DOI: 10.1016/j.chembiol.2014.08.016] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2013] [Revised: 08/03/2014] [Accepted: 08/05/2014] [Indexed: 02/07/2023]
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137
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Endo Y, Noguchi S, Hara Y, Hayashi YK, Motomura K, Miyatake S, Murakami N, Tanaka S, Yamashita S, Kizu R, Bamba M, Goto YI, Matsumoto N, Nonaka I, Nishino I. Dominant mutations in ORAI1 cause tubular aggregate myopathy with hypocalcemia via constitutive activation of store-operated Ca²⁺ channels. Hum Mol Genet 2014; 24:637-48. [PMID: 25227914 DOI: 10.1093/hmg/ddu477] [Citation(s) in RCA: 113] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The store-operated Ca(2+) release-activated Ca(2+) (CRAC) channel is activated by diminished luminal Ca(2+) levels in the endoplasmic reticulum and sarcoplasmic reticulum (SR), and constitutes one of the major Ca(2+) entry pathways in various tissues. Tubular aggregates (TAs) are abnormal structures in the skeletal muscle, and although their mechanism of formation has not been clarified, altered Ca(2+) homeostasis related to a disordered SR is suggested to be one of the main contributing factors. TA myopathy is a hereditary muscle disorder that is pathologically characterized by the presence of TAs. Recently, dominant mutations in the STIM1 gene, encoding a Ca(2+) sensor that controls CRAC channels, have been identified to cause tubular aggregate myopathy (TAM). Here, we identified heterozygous missense mutations in the ORAI1 gene, encoding the CRAC channel itself, in three families affected by dominantly inherited TAM with hypocalcemia. Skeletal myotubes from an affected individual and HEK293 cells expressing mutated ORAI1 proteins displayed spontaneous extracellular Ca(2+) entry into cells without diminishment of luminal Ca(2+) or the association with STIM1. Our results indicate that STIM1-independent activation of CRAC channels induced by dominant mutations in ORAI1 cause altered Ca(2+) homeostasis, resulting in TAM with hypocalcemia.
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Affiliation(s)
- Yukari Endo
- Department of Clinical Development, Translational Medical Center, National Center of Neurology and Psychiatry, Kodaira, Tokyo 187-8556, Japan Department of Neuromuscular Research and Department of Pediatrics, Kyoto University Graduate School of Medicine, Kyoto 606-8507, Japan
| | - Satoru Noguchi
- Department of Clinical Development, Translational Medical Center, National Center of Neurology and Psychiatry, Kodaira, Tokyo 187-8556, Japan Department of Neuromuscular Research and
| | - Yuji Hara
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan Tokyo Women's Medical University Institute for Integrated Medical Sciences (TIIMS), Shinjuku, Tokyo 162-8666, Japan
| | - Yukiko K Hayashi
- Department of Clinical Development, Translational Medical Center, National Center of Neurology and Psychiatry, Kodaira, Tokyo 187-8556, Japan Department of Neuromuscular Research and Department of Neurophysiology, Tokyo Medical University, Tokyo 160-8402, Japan
| | - Kazushi Motomura
- Department of Clinical Development, Translational Medical Center, National Center of Neurology and Psychiatry, Kodaira, Tokyo 187-8556, Japan
| | - Satoko Miyatake
- Department of Human Genetics, Graduate School of Medicine, Yokohama City University, Yokohama 236-0004, Japan
| | - Nobuyuki Murakami
- Department of Pediatrics, Dokkyo Medical University, Koshigaya Hospital, Koshigaya, Saitama 343-8555, Japan
| | - Satsuki Tanaka
- Department of Diabetes and Endocrinology, Osaka Saiseikai Nakatsu Hospital, Osaka 530-0012, Japan
| | - Sumimasa Yamashita
- Division of Pediatric Neurology, Kanagawa Children's Medical Center (KCMC), Yokohama 232-8555, Japan
| | - Rika Kizu
- Division of Pediatrics, Yokosuka Kyosai Hospital, Yokosuka, Kanagawa 238-8558, Japan and
| | - Masahiro Bamba
- Division of Pediatrics, Kawasaki Municipal Hospital, Kawasaki, Kanagawa 210-0013, Japan
| | - Yu-Ichi Goto
- Department of Clinical Development, Translational Medical Center, National Center of Neurology and Psychiatry, Kodaira, Tokyo 187-8556, Japan Department of Mental Retardation and Birth Defect Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Kodaira, Tokyo 187-8502, Japan
| | - Naomichi Matsumoto
- Department of Human Genetics, Graduate School of Medicine, Yokohama City University, Yokohama 236-0004, Japan
| | | | - Ichizo Nishino
- Department of Clinical Development, Translational Medical Center, National Center of Neurology and Psychiatry, Kodaira, Tokyo 187-8556, Japan Department of Neuromuscular Research and
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138
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Store-operated CRAC channels regulate gene expression and proliferation in neural progenitor cells. J Neurosci 2014; 34:9107-23. [PMID: 24990931 DOI: 10.1523/jneurosci.0263-14.2014] [Citation(s) in RCA: 101] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Calcium signals regulate many critical processes during vertebrate brain development including neurogenesis, neurotransmitter specification, and axonal outgrowth. However, the identity of the ion channels mediating Ca(2+) signaling in the developing nervous system is not well defined. Here, we report that embryonic and adult mouse neural stem/progenitor cells (NSCs/NPCs) exhibit store-operated Ca(2+) entry (SOCE) mediated by Ca(2+) release-activated Ca(2+) (CRAC) channels. SOCE in NPCs was blocked by the CRAC channel inhibitors La(3+), BTP2, and 2-APB and Western blots revealed the presence of the canonical CRAC channel proteins STIM1 and Orai1. Knock down of STIM1 or Orai1 significantly diminished SOCE in NPCs, and SOCE was lost in NPCs from transgenic mice lacking Orai1 or STIM1 and in knock-in mice expressing the loss-of-function Orai1 mutant, R93W. Therefore, STIM1 and Orai1 make essential contributions to SOCE in NPCs. SOCE in NPCs was activated by epidermal growth factor and acetylcholine, the latter occurring through muscarinic receptors. Activation of SOCE stimulated gene transcription through calcineurin/NFAT (nuclear factor of activated T cells) signaling through a mechanism consistent with local Ca(2+) signaling by Ca(2+) microdomains near CRAC channels. Importantly, suppression or deletion of STIM1 and Orai1 expression significantly attenuated proliferation of embryonic and adult NPCs cultured as neurospheres and, in vivo, in the subventricular zone of adult mice. These findings show that CRAC channels serve as a major route of Ca(2+) entry in NPCs and regulate key effector functions including gene expression and proliferation, indicating that CRAC channels are important regulators of mammalian neurogenesis.
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139
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Dong H, Klein ML, Fiorin G. Counterion-Assisted Cation Transport in a Biological Calcium Channel. J Phys Chem B 2014; 118:9668-76. [DOI: 10.1021/jp5059897] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Hao Dong
- Institute for Computational
Molecular Science, Temple University, Philadelphia, Pennsylvania 19122, United States
| | - Michael L. Klein
- Institute for Computational
Molecular Science, Temple University, Philadelphia, Pennsylvania 19122, United States
| | - Giacomo Fiorin
- Institute for Computational
Molecular Science, Temple University, Philadelphia, Pennsylvania 19122, United States
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140
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Amcheslavsky A, Safrina O, Cahalan MD. Orai3 TM3 point mutation G158C alters kinetics of 2-APB-induced gating by disulfide bridge formation with TM2 C101. ACTA ACUST UNITED AC 2014; 142:405-12. [PMID: 24081982 PMCID: PMC3787773 DOI: 10.1085/jgp.201311030] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
After endoplasmic reticulum (ER) Ca2+ store depletion, Orai channels in the plasma membrane (PM) are activated directly by ER-resident STIM proteins to form the Ca2+-selective Ca2+ release–activated Ca2+ (CRAC) channel. However, in the absence of Ca2+ store depletion and STIM interaction, the mammalian homologue Orai3 can be activated by 2-aminoethyl diphenylborinate (2-APB), resulting in a nonselective cation conductance characterized by biphasic inward and outward rectification. Here, we use site-directed mutagenesis and patch-clamp analysis to better understand the mechanism by which 2-APB activates Orai3. We find that point mutation of glycine 158 in the third transmembrane (TM) segment to cysteine, but not alanine, slows the kinetics of 2-APB activation and prevents complete channel closure upon 2-APB washout. The “slow” phenotype exhibited by Orai3 mutant G158C reveals distinct open states, characterized by variable reversal potentials. The slow phenotype can be reversed by application of the reducing reagent bis(2-mercaptoethylsulfone) (BMS), but in a state-dependent manner, only during 2-APB activation. Moreover, the double mutant C101G/G158C, in which an endogenous TM2 cysteine is changed to glycine, does not exhibit altered kinetics of 2-APB activation. We suggest that a disulfide bridge, formed between the introduced cysteine at TM3 position 158 and the endogenous cysteine at TM2 position 101, hinders transitions between Orai3 open and closed states. Our data provide functional confirmation of the proximity of these two residues and suggest a location within the Orai3 protein that is sensitive to the actions of 2-APB.
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Affiliation(s)
- Anna Amcheslavsky
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, CA 92697
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141
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Amcheslavsky A, Safrina O, Cahalan MD. State-dependent block of Orai3 TM1 and TM3 cysteine mutants: insights into 2-APB activation. ACTA ACUST UNITED AC 2014; 143:621-31. [PMID: 24733836 PMCID: PMC4003185 DOI: 10.1085/jgp.201411171] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Residue E165, in transmembrane helix 3, participates in formation of the dilated pore of the 2-APB–activated Orai3 channel but not that of the more selective store-operated Orai3 pore. After endoplasmic reticulum (ER) Ca2+ store depletion, Orai channels in the plasma membrane (PM) are activated directly by ER-resident stromal interacting molecule (STIM) proteins to form the Ca2+-selective Ca2+ release-activated Ca2+ (CRAC) channel. Of the three human Orai channel homologues, only Orai3 can be activated by high concentrations (>50 µM) of 2-aminoethyl diphenylborinate (2-APB). 2-APB activation of Orai3 occurs without STIM1–Orai3 interaction or store depletion, and results in a cationic, nonselective current characterized by biphasic inward and outward rectification. Here we use cysteine scanning mutagenesis, thiol-reactive reagents, and patch-clamp analysis to define the residues that assist in formation of the 2-APB–activated Orai3 pore. Mutating transmembrane (TM) 1 residues Q83, V77, and L70 to cysteine results in potentiated block by cadmium ions (Cd2+). TM1 mutants E81C, G73A, G73C, and R66C form channels that are not sensitive to 2-APB activation. We also find that Orai3 mutant V77C is sensitive to block by 2-aminoethyl methanethiosulfonate (MTSEA), but not 2-(trimethylammonium)ethyl methanethiosulfonate (MTSET). Block induced by reaction with MTSEA is state dependent, as it occurs only when Orai3-V77C channels are opened by either 2-APB or by cotransfection with STIM1 and concurrent passive store depletion. We also analyzed TM3 residue E165. Mutation E165A in Orai3 results in diminished 2-APB–activated currents. However, it has little effect on store-operated current density. Furthermore, mutation E165C results in Cd2+-induced block that is state dependent: Cd2+ only blocks 2-APB–activated, not store-operated, mutant channels. Our data suggest that the dilated pore of 2-APB–activated Orai3 is lined by TM1 residues, but also allows for TM3 E165 to approach the central axis of the channel that forms the conducting pathway, or pore.
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Affiliation(s)
- Anna Amcheslavsky
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, CA 92697
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142
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Zeng B, Chen GL, Daskoulidou N, Xu SZ. The ryanodine receptor agonist 4-chloro-3-ethylphenol blocks ORAI store-operated channels. Br J Pharmacol 2014; 171:1250-9. [PMID: 24670147 PMCID: PMC3952802 DOI: 10.1111/bph.12528] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2013] [Revised: 10/21/2013] [Accepted: 11/06/2013] [Indexed: 01/05/2023] Open
Abstract
BACKGROUND Depletion of the Ca(2+) store by ryanodine receptor (RyR) agonists induces store-operated Ca(2+) entry (SOCE). 4-Chloro-3-ethylphenol (4-CEP) and 4-chloro-m-cresol (4-CmC) are RyR agonists commonly used as research tools and diagnostic reagents for malignant hyperthermia. Here, we investigated the effects of 4-CEP and its analogues on SOCE. EXPERIMENTAL APPROACH SOCE and ORAI1-3 currents were recorded by Ca(2+) imaging and whole-cell patch recordings in rat L6 myoblasts and in HEK293 cells overexpressing STIM1/ORAI1-3. KEY RESULTS 4-CEP induced a significant release of Ca(2+) in rat L6 myoblasts, but inhibited SOCE. The inhibitory effect was concentration-dependent and more potent than its analogues 4-CmC and 4-chlorophenol (4-ClP). In the HEK293 T-REx cells overexpressing STIM1/ORAI1-3, 4-CEP inhibited the ORAI1, ORAI2 and ORAI3 currents evoked by thapsigargin. The 2-APB-induced ORAI3 current was also blocked by 4-CEP. This inhibitory effect was reversible and independent of the Ca(2+) release. The two analogues, 4-CmC and 4-ClP, also inhibited the ORAI1-3 channels. Excised patch and intracellular application of 4-CEP demonstrated that the action site was located extracellularly. Moreover, 4-CEP evoked STIM1 translocation and subplasmalemmal clustering through its Ca(2+) store-depleting effect via the activation of RyR, but no effect on STIM1 redistribution was observed in cells co-expressing STIM1/ORAI1-3. CONCLUSION AND IMPLICATIONS 4-CEP not only acts as a RyR agonist to deplete the Ca(2+) store and trigger STIM1 subplasmalemmal translocation and clustering, but also directly inhibits ORAI1-3 channels. These findings demonstrate a novel pharmacological property for the chlorophenol derivatives that act as RyR agonists.
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Affiliation(s)
- Bo Zeng
- Centre for Cardiovascular and Metabolic Research, Hull York Medical School, University of HullHull, UK
| | - Gui-Lan Chen
- Centre for Cardiovascular and Metabolic Research, Hull York Medical School, University of HullHull, UK
- Key Laboratory for Medical Electrophysiology, Ministry of Education of China, and the Institute of Cardiovascular Research, Luzhou Medical CollegeLuzhou, China
| | - Nikoleta Daskoulidou
- Centre for Cardiovascular and Metabolic Research, Hull York Medical School, University of HullHull, UK
| | - Shang-Zhong Xu
- Centre for Cardiovascular and Metabolic Research, Hull York Medical School, University of HullHull, UK
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143
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Hoth M, Niemeyer BA. The neglected CRAC proteins: Orai2, Orai3, and STIM2. CURRENT TOPICS IN MEMBRANES 2014; 71:237-71. [PMID: 23890118 DOI: 10.1016/b978-0-12-407870-3.00010-x] [Citation(s) in RCA: 97] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Plasma-membrane-localized Orai1 ion channel subunits interacting with ER-localized STIM1 molecules comprise the major subunit composition responsible for calcium release-activated calcium channels. STIM1 "translates" the Ca(2+) store content into Orai1 activity, making it a store-operated channel. Surprisingly, in addition to being the physical activator, STIM1 also modulates Orai1 properties, including its inactivation and permeation (see Chapter 1). STIM1 is thus more than a pure Orai1 activator. Within the past 7 years following the discovery of STIM and Orai proteins, the molecular mechanisms of STIM1/Orai1 activity and their functional importance have been studied in great detail. Much less is currently known about the other isoforms STIM2, Orai2, and Orai3. In this chapter, we summarize the current knowledge about STIM2, Orai2, and Orai3 properties and function. Are these homologues mainly modulators of predominantly STIM1/Orai1-mediated complexes or do store-dependent or -independent functions such as regulation of basal Ca(2+) concentration and activation of Orai3-containing complexes by arachidonic acid or by estrogen receptors point toward their "true" physiological function? Is Orai2 the Orai1 of neurons? A major focus of the review is on the functional relevance of STIM2, Orai2, and Orai3, some of which still remains speculative.
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Affiliation(s)
- Markus Hoth
- Department of Biophysics, Saarland University, Homburg, Germany
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144
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Scrimgeour NR, Wilson DP, Barritt GJ, Rychkov GY. Structural and stoichiometric determinants of Ca2+ release-activated Ca2+ (CRAC) channel Ca2+-dependent inactivation. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2014; 1838:1281-7. [PMID: 24472513 DOI: 10.1016/j.bbamem.2014.01.019] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2013] [Revised: 01/03/2014] [Accepted: 01/14/2014] [Indexed: 10/25/2022]
Abstract
Depletion of intracellular Ca(2+) stores in mammalian cells results in Ca(2+) entry across the plasma membrane mediated primarily by Ca(2+) release-activated Ca(2+) (CRAC) channels. Ca(2+) influx through these channels is required for the maintenance of homeostasis and Ca(2+) signaling in most cell types. One of the main features of native CRAC channels is fast Ca(2+)-dependent inactivation (FCDI), where Ca(2+) entering through the channel binds to a site near its intracellular mouth and causes a conformational change, closing the channel and limiting further Ca(2+) entry. Early studies suggested that FCDI of CRAC channels was mediated by calmodulin. However, since the discovery of STIM1 and Orai1 proteins as the basic molecular components of the CRAC channel, it has become apparent that FCDI is a more complex phenomenon. Data obtained using heterologous overexpression of STIM1 and Orai1 suggest that, in addition to calmodulin, several cytoplasmic domains of STIM1 and Orai1 and the selectivity filter within the channel pore are required for FCDI. The stoichiometry of STIM1 binding to Orai1 also has emerged as an important determinant of FCDI. Consequently, STIM1 protein expression levels have the potential to be an endogenous regulator of CRAC channel Ca(2+) influx. This review discusses the current understanding of the molecular mechanisms governing the FCDI of CRAC channels, including an evaluation of further experiments that may delineate whether STIM1 and/or Orai1 protein expression is endogenously regulated to modulate CRAC channel function, or may be dysregulated in some pathophysiological states.
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Affiliation(s)
- Nathan R Scrimgeour
- School of Medical Sciences, University of Adelaide, Adelaide, South Australia 5005, Australia
| | - David P Wilson
- School of Medical Sciences, University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Greg J Barritt
- Department of Medical Biochemistry, School of Medicine, Flinders University, Adelaide, South Australia 5001, Australia
| | - Grigori Y Rychkov
- School of Medical Sciences, University of Adelaide, Adelaide, South Australia 5005, Australia.
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145
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Opening of an alternative ion permeation pathway in a nociceptor TRP channel. Nat Chem Biol 2014; 10:188-95. [DOI: 10.1038/nchembio.1428] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2013] [Accepted: 11/04/2013] [Indexed: 11/08/2022]
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146
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Wang X, Wang Y, Zhou Y, Hendron E, Mancarella S, Andrake MD, Rothberg BS, Soboloff J, Gill DL. Distinct Orai-coupling domains in STIM1 and STIM2 define the Orai-activating site. Nat Commun 2014; 5:3183. [PMID: 24492416 PMCID: PMC3995141 DOI: 10.1038/ncomms4183] [Citation(s) in RCA: 137] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2013] [Accepted: 12/27/2013] [Indexed: 12/11/2022] Open
Abstract
STIM1 and STIM2 are widely expressed endoplasmic reticulum (ER) Ca(2+) sensor proteins able to translocate within the ER membrane to physically couple with and gate plasma membrane Orai Ca(2+) channels. Although they are structurally similar, we reveal critical differences in the function of the short STIM-Orai-activating regions (SOAR) of STIM1 and STIM2. We narrow these differences in Orai1 gating to a strategically exposed phenylalanine residue (Phe-394) in SOAR1, which in SOAR2 is substituted by a leucine residue. Remarkably, in full-length STIM1, replacement of Phe-394 with the dimensionally similar but polar histidine head group prevents both Orai1 binding and gating, creating an Orai1 non-agonist. Thus, this residue is critical in tuning the efficacy of Orai activation. While STIM1 is a full Orai1-agonist, leucine-replacement of this crucial residue in STIM2 endows it with partial agonist properties, which may be critical for limiting Orai1 activation stemming from its enhanced sensitivity to store-depletion.
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Affiliation(s)
- Xizhuo Wang
- Department of Biochemistry, Temple University School of Medicine, Philadelphia, PA 19140
| | - Youjun Wang
- Department of Biochemistry, Temple University School of Medicine, Philadelphia, PA 19140
- Beijing Key Laboratory of Gene Resources and Molecular Development College of Life Sciences, Beijing Normal University, Beijing 100875, P.R. China
| | - Yandong Zhou
- Department of Biochemistry, Temple University School of Medicine, Philadelphia, PA 19140
| | - Eunan Hendron
- Department of Biochemistry, Temple University School of Medicine, Philadelphia, PA 19140
| | - Salvatore Mancarella
- Department of Biochemistry, Temple University School of Medicine, Philadelphia, PA 19140
| | - Mark D. Andrake
- Institute for Cancer Research, Fox Chase Cancer Center, Philadelphia PA 19111
| | - Brad S. Rothberg
- Department of Biochemistry, Temple University School of Medicine, Philadelphia, PA 19140
| | - Jonathan Soboloff
- Department of Biochemistry, Temple University School of Medicine, Philadelphia, PA 19140
| | - Donald L. Gill
- Department of Biochemistry, Temple University School of Medicine, Philadelphia, PA 19140
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147
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Abstract
The TRPC1 ion channel was the first mammalian TRP channel to be cloned. In humans, it is encoded by the TRPC1 gene located in chromosome 3. The protein is predicted to consist of six transmembrane segments with the N- and C-termini located in the cytoplasm. The extracellular loop connecting transmembrane segments 5 and 6 participates in the formation of the ionic pore region. Inside the cell, TRPC1 is present in the endoplasmic reticulum, plasma membrane, intracellular vesicles, and primary cilium, an antenna-like sensory organelle functioning as a signaling platform. In human and rodent tissues, it shows an almost ubiquitous expression. TRPC1 interacts with a diverse group of proteins including ion channel subunits, receptors, and cytosolic proteins to mediate its effect on Ca(2+) signaling. It primarily functions as a cation nonselective channel within pathways controlling Ca(2+) entry in response to cell surface receptor activation. Through these pathways, it affects basic cell functions, such as proliferation and survival, differentiation, secretion, and cell migration, as well as cell type-specific functions such as chemotropic turning of neuronal growth cones and myoblast fusion. The biological role of TRPC1 has been studied in genetically engineered mice where the Trpc1 gene has been experimentally ablated. Although these mice live to adulthood, they show defects in several organs and tissues, such as the cardiovascular, central nervous, skeletal and muscular, and immune systems. Genetic and functional studies have implicated TRPC1 in diabetic nephropathy, Parkinson's disease, Huntington's disease, Duchenne muscular dystrophy, cancer, seizures, and Darier-White skin disease.
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Affiliation(s)
- Vasyl Nesin
- Department of Cell Biology, University of Oklahoma Health Sciences Center, 975 NE 10th Street, Oklahoma City, OK, 73104, USA
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148
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Choi S, Maleth J, Jha A, Lee KP, Kim MS, So I, Ahuja M, Muallem S. The TRPCs-STIM1-Orai interaction. Handb Exp Pharmacol 2014; 223:1035-54. [PMID: 24961979 DOI: 10.1007/978-3-319-05161-1_13] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Ca(2+) signaling entails receptor-stimulated Ca(2+) release from the ER stores that serves as a signal to activate Ca(2+) influx channels present at the plasma membrane, the store-operated Ca(2+) channels (SOCs). The two known SOCs are the Orai and TRPC channels. The SOC-dependent Ca(2+) influx mediates and sustains virtually all Ca(2+)-dependent regulatory functions. The signal that transmits the Ca(2+) content of the ER stores to the plasma membrane is the ER resident, Ca(2+)-binding protein STIM1. STIM1 is a multidomain protein that clusters and dimerizes in response to Ca(2+) store depletion leading to activation of Orai and TRPC channels. Activation of the Orais by STIM1 is obligatory for their function as SOCs, while TRPC channels can function as both STIM1-dependent and STIM1-independent channels. Here we discuss the different mechanisms by which STIM1 activates the Orai and TRPC channels, the emerging specific and non-overlapping physiological functions of Ca(2+) influx mediated by the two channel types, and argue that the TRPC channels should be the preferred therapeutic target to control the toxic effect of excess Ca(2+) influx.
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Affiliation(s)
- Seok Choi
- Epithelial Signaling and Transport Section, Molecular Physiology and Therapeutics Branch, National Institute of Dental and Craniofacial Research, National Institute of Health, Bethesda, MD, 20892, USA
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149
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Cox JH, Hussell S, Søndergaard H, Roepstorff K, Bui JV, Deer JR, Zhang J, Li ZG, Lamberth K, Kvist PH, Padkjær S, Haase C, Zahn S, Odegard VH. Antibody-mediated targeting of the Orai1 calcium channel inhibits T cell function. PLoS One 2013; 8:e82944. [PMID: 24376610 PMCID: PMC3871607 DOI: 10.1371/journal.pone.0082944] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2013] [Accepted: 11/08/2013] [Indexed: 01/03/2023] Open
Abstract
Despite the attractiveness of ion channels as therapeutic targets, there are no examples of monoclonal antibodies directed against ion channels in clinical development. Antibody-mediated inhibition of ion channels could offer a directed, specific therapeutic approach. To investigate the potential of inhibiting ion channel function with an antibody, we focused on Orai1, the pore subunit of the calcium channel responsible for store-operated calcium entry (SOCE) in T cells. Effector T cells are key drivers of autoimmune disease pathogenesis and calcium signaling is essential for T cell activation, proliferation, and cytokine production. We show here the generation of a specific anti-human Orai1 monoclonal antibody (mAb) against an extracellular loop of the plasma membrane-spanning protein. The anti-Orai1 mAb binds native Orai1 on lymphocytes and leads to cellular internalization of the channel. As a result, T cell proliferation, and cytokine production is inhibited in vitro. In vivo, anti-Orai1 mAb is efficacious in a human T cell-mediated graft-versus host disease (GvHD) mouse model. This study demonstrates the feasibility of antibody-mediated inhibition of Orai1 function and, more broadly, reveals the possibility of targeting ion channels with biologics for the treatment of autoimmunity and other diseases.
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Affiliation(s)
- Jennifer H. Cox
- Department of Cellular Immunology, Novo Nordisk Research Center, Seattle, Washington, United States of America
| | - Scott Hussell
- Department of Cellular Immunology, Novo Nordisk Research Center, Seattle, Washington, United States of America
| | | | | | - John-Vu Bui
- Department of Cellular Immunology, Novo Nordisk Research Center, Seattle, Washington, United States of America
| | - Jen Running Deer
- Department of Molecular Immunology, Novo Nordisk Research Center, Seattle, Washington, United States of America
| | - Jun Zhang
- Department of Cell Biology, Beijing Novo Nordisk Pharmaceuticals Science & Technology Co., Beijing, China
| | - Zhan-Guo Li
- Department of Rheumatology & Immunology, Beijing University People’s Hospital, Beijing, China
| | - Kasper Lamberth
- Department of Screening and Cell Technology, Novo Nordisk A/S, Maløv, Denmark
| | | | - Søren Padkjær
- Department of Protein Structure and Biophysics, Novo Nordisk A/S, Maløv, Denmark
| | - Claus Haase
- Department of Immunopharmacology, Novo Nordisk A/S, Maløv, Denmark
| | - Stefan Zahn
- Department of Antibody Technology, Novo Nordisk A/S, Maløv, Denmark
| | - Valerie H. Odegard
- Department of Cellular Immunology, Novo Nordisk Research Center, Seattle, Washington, United States of America
- * E-mail:
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Kim KD, Srikanth S, Tan YV, Yee MK, Jew M, Damoiseaux R, Jung ME, Shimizu S, An DS, Ribalet B, Waschek JA, Gwack Y. Calcium signaling via Orai1 is essential for induction of the nuclear orphan receptor pathway to drive Th17 differentiation. THE JOURNAL OF IMMUNOLOGY 2013; 192:110-22. [PMID: 24307733 DOI: 10.4049/jimmunol.1302586] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Orai1 is the pore subunit of Ca(2+) release-activated Ca(2+) (CRAC) channels that stimulate downstream signaling pathways crucial for T cell activation. CRAC channels are an attractive therapeutic target for alleviation of autoimmune diseases. Using high-throughput chemical library screening targeting Orai1, we identified a novel class of small molecules that inhibit CRAC channel activity. One of these molecules, compound 5D, inhibited CRAC channel activity by blocking ion permeation. When included during differentiation, Th17 cells showed higher sensitivity to compound 5D than Th1 and Th2 cells. The selectivity was attributable to high dependence of promoters of retinoic-acid-receptor-related orphan receptors on the Ca(2+)-NFAT pathway. Blocking of CRAC channels drastically decreased recruitment of NFAT and histone modifications within key gene loci involved in Th17 differentiation. The impairment in Th17 differentiation by treatment with CRAC channel blocker was recapitulated in Orai1-deficient T cells, which could be rescued by exogenous expression of retinoic-acid-receptor-related orphan receptors or a constitutive active mutant of NFAT. In vivo administration of CRAC channel blockers effectively reduced the severity of experimental autoimmune encephalomyelitis by suppression of differentiation of inflammatory T cells. These results suggest that CRAC channel blockers can be considered as chemical templates for the development of therapeutic agents to suppress inflammatory responses.
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Affiliation(s)
- Kyun-Do Kim
- Department of Physiology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
| | - Sonal Srikanth
- Department of Physiology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
| | - Yossan-Var Tan
- The NPI-Semel Institute and Department of Psychiatry, David Geffen School of Medicine at UCLA, Los Angeles, CA 90024, USA
| | - Ma-Khin Yee
- Department of Physiology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
| | - Marcus Jew
- Department of Physiology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
| | - Robert Damoiseaux
- Molecular Screening Shared Resources, UC CEIN, NanoSystems Institute, University of California, Los Angeles, CA90095, USA
| | - Michael E Jung
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA90095, USA
| | - Saki Shimizu
- Division of Hematology-Oncology, David Geffen School of Medicine at UCLA.,UCLA AIDS Institute, Los Angeles, CA 90095, USA
| | - Dong Sung An
- Division of Hematology-Oncology, David Geffen School of Medicine at UCLA.,UCLA AIDS Institute, Los Angeles, CA 90095, USA.,UCLA School of Nursing, Los Angeles, CA 90095, USA
| | - Bernard Ribalet
- Department of Physiology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
| | - James A Waschek
- The NPI-Semel Institute and Department of Psychiatry, David Geffen School of Medicine at UCLA, Los Angeles, CA 90024, USA
| | - Yousang Gwack
- Department of Physiology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
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