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Ong HL, Ambudkar IS. "Gatekeepers of heaven" breaking bad. Cell Calcium 2024; 118:102842. [PMID: 38211552 DOI: 10.1016/j.ceca.2023.102842] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Accepted: 12/20/2023] [Indexed: 01/13/2024]
Affiliation(s)
- Hwei Ling Ong
- Secretory Physiology Section, National Institutes of Health, National Institute of Dental and Craniofacial Research, Bethesda, MD 20892, USA
| | - Indu S Ambudkar
- Secretory Physiology Section, National Institutes of Health, National Institute of Dental and Craniofacial Research, Bethesda, MD 20892, USA.
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Carney CP, Pandey N, Kapur A, Saadi H, Ong HL, Chen C, Winkles JA, Woodworth GF, Kim AJ. Impact of Targeting Moiety Type and Protein Corona Formation on the Uptake of Fn14-Targeted Nanoparticles by Cancer Cells. ACS Nano 2023; 17:19667-19684. [PMID: 37812740 DOI: 10.1021/acsnano.3c02575] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/11/2023]
Abstract
The TWEAK receptor, Fn14, is a promising candidate for active targeting of cancer nanotherapeutics to many solid tumor types, including metastatic breast and primary brain cancers. Targeting of therapeutic nanoparticles (NPs) has been accomplished using a range of targeting moieties including monoclonal antibodies and related fragments, peptides, and small molecules. Here, we investigated a full-length Fn14-specific monoclonal antibody, ITEM4, or an ITEM4-Fab fragment as a targeting moiety to guide the development of a clinical formulation. We formulated NPs with varying densities of the targeting moieties while maintaining the decreased nonspecific adhesivity with receptor targeting (DART) characteristics. To model the conditions that NPs experience following intravenous infusion, we investigated the impact of serum exposure in relation to the targeting moiety type and surface density. To further evaluate performance at the cancer cell level, we performed experiments to assess differences in cellular uptake and trafficking in several cancer cell lines using confocal microscopy, imaging flow cytometry, and total internal reflection fluorescence microscopy. We observed that Fn14-targeted NPs exhibit enhanced cellular uptake in Fn14-high compared to Fn14-low cancer cells and that in both cell lines uptake levels were greater than observed with control, nontargeted NPs. We found that serum exposure increased Fn14-targeted NP specificity while simultaneously reducing the total NP uptake. Importantly, serum exposure caused a larger reduction in cancer cell uptake over time when the targeting moiety was an antibody fragment (Fab region of the monoclonal antibody) compared with the full-length monoclonal antibody targeting moiety. Lastly, we uncovered that full monoclonal antibody-targeted NPs enter cancer cells via clathrin-mediated endocytosis and traffic through the endolysosomal pathway. Taken together, these results support a pathway for developing a clinical formulation using a full-length Fn14 monoclonal antibody as the targeting moiety for a DART cancer nanotherapeutic agent.
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Affiliation(s)
- Christine P Carney
- Department of Neurosurgery, University of Maryland School of Medicine, Baltimore, Maryland 21201, United States
- Marlene and Stewart Greenebaum Comprehensive Cancer Center, University of Maryland School of Medicine, Baltimore, Maryland 21201, United States
| | - Nikhil Pandey
- Department of Neurosurgery, University of Maryland School of Medicine, Baltimore, Maryland 21201, United States
- Marlene and Stewart Greenebaum Comprehensive Cancer Center, University of Maryland School of Medicine, Baltimore, Maryland 21201, United States
| | - Anshika Kapur
- Department of Neurosurgery, University of Maryland School of Medicine, Baltimore, Maryland 21201, United States
- Marlene and Stewart Greenebaum Comprehensive Cancer Center, University of Maryland School of Medicine, Baltimore, Maryland 21201, United States
| | - Hassan Saadi
- Department of Neurosurgery, University of Maryland School of Medicine, Baltimore, Maryland 21201, United States
- Marlene and Stewart Greenebaum Comprehensive Cancer Center, University of Maryland School of Medicine, Baltimore, Maryland 21201, United States
| | - Hwei Ling Ong
- Secretory Physiology Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Chixiang Chen
- Department of Neurosurgery, University of Maryland School of Medicine, Baltimore, Maryland 21201, United States
- Department of Epidemiology & Public Health, University of Maryland School of Medicine, Baltimore, Maryland 21201, United States
| | - Jeffrey A Winkles
- Department of Neurosurgery, University of Maryland School of Medicine, Baltimore, Maryland 21201, United States
- Marlene and Stewart Greenebaum Comprehensive Cancer Center, University of Maryland School of Medicine, Baltimore, Maryland 21201, United States
- Center for Vascular and Inflammatory Diseases, University of Maryland School of Medicine, Baltimore, Maryland 21201, United States
| | - Graeme F Woodworth
- Department of Neurosurgery, University of Maryland School of Medicine, Baltimore, Maryland 21201, United States
- Marlene and Stewart Greenebaum Comprehensive Cancer Center, University of Maryland School of Medicine, Baltimore, Maryland 21201, United States
- Fischell Department of Bioengineering, A. James Clarke School of Engineering, University of Maryland, College Park, Maryland 20742, United States
| | - Anthony J Kim
- Department of Neurosurgery, University of Maryland School of Medicine, Baltimore, Maryland 21201, United States
- Marlene and Stewart Greenebaum Comprehensive Cancer Center, University of Maryland School of Medicine, Baltimore, Maryland 21201, United States
- Fischell Department of Bioengineering, A. James Clarke School of Engineering, University of Maryland, College Park, Maryland 20742, United States
- Department of Pharmacology, University of Maryland School of Medicine, Baltimore, Maryland 21201, United States
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, Maryland 21201, United States
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Shvetsov SA, Orlova T, Emelyanenko AV, Zolot'ko AS, Ong HL. Optical nonlinearity of a dual-frequency nematic liquid crystal via temperature-mediated mapping of dielectric anisotropy. Opt Express 2022; 30:47909-47920. [PMID: 36558708 DOI: 10.1364/oe.478321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Accepted: 12/02/2022] [Indexed: 06/17/2023]
Abstract
Liquid crystals are of great interest in the field of nonlinear optics due to their efficient response to low intensity light fields. Here we present a new, to the best of our knowledge, mechanism of a nonlinear optical response which is observed for a dye-doped dual-frequency nematic liquid crystal. The local increase in temperature caused by the absorption of light beam in the liquid crystal medium leads to spatial variation and inversion of the sign of the dielectric anisotropy. When an alternating current electric field with a frequency close to the cross-over frequency is applied to the liquid crystal cell, the planar orientation sustains at the beam periphery, but elastic deformation occurs in the irradiation region. In the case of a dye dopant with negative absorption dichroism, a first-order orientational transition with large bistability region is obtained.
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Ahmad M, Ong HL, Saadi H, Son GY, Shokatian Z, Terry LE, Trebak M, Yule DI, Ambudkar I. Functional communication between IP 3R and STIM2 at subthreshold stimuli is a critical checkpoint for initiation of SOCE. Proc Natl Acad Sci U S A 2022; 119:e2114928118. [PMID: 35022238 PMCID: PMC8784118 DOI: 10.1073/pnas.2114928118] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Accepted: 11/19/2021] [Indexed: 02/08/2023] Open
Abstract
Stromal interaction molecules, STIM1 and STIM2, sense decreases in the endoplasmic reticulum (ER) [Ca2+] ([Ca2+]ER) and cluster in ER-plasma membrane (ER-PM) junctions where they recruit and activate Orai1. While STIM1 responds when [Ca2+]ER is relatively low, STIM2 displays constitutive clustering in the junctions and is suggested to regulate basal Ca2+ entry. The cellular cues that determine STIM2 clustering under basal conditions is not known. By using gene editing to fluorescently tag endogenous STIM2, we report that endogenous STIM2 is constitutively localized in mobile and immobile clusters. The latter associate with ER-PM junctions and recruit Orai1 under basal conditions. Agonist stimulation increases immobile STIM2 clusters, which coordinate recruitment of Orai1 and STIM1 to the junctions. Extended synaptotagmin (E-Syt)2/3 are required for forming the ER-PM junctions, but are not sufficient for STIM2 clustering. Importantly, inositol 1,4,5-triphosphate receptor (IP3R) function and local [Ca2+]ER are the main drivers of immobile STIM2 clusters. Enhancing, or decreasing, IP3R function at ambient [IP3] causes corresponding increase, or attenuation, of immobile STIM2 clusters. We show that immobile STIM2 clusters denote decreases in local [Ca2+]ER mediated by IP3R that is sensed by the STIM2 N terminus. Finally, under basal conditions, ambient PIP2-PLC activity of the cell determines IP3R function, immobilization of STIM2, and basal Ca2+ entry while agonist stimulation augments these processes. Together, our findings reveal that immobilization of STIM2 clusters within ER-PM junctions, a first response to ER-Ca2+ store depletion, is facilitated by the juxtaposition of IP3R and marks a checkpoint for initiation of Ca2+ entry.
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Affiliation(s)
- Moaz Ahmad
- Secretory Physiology Section, National Institute of Dental and Craniofacial Research, NIH, Bethesda, MD 20892
| | - Hwei Ling Ong
- Secretory Physiology Section, National Institute of Dental and Craniofacial Research, NIH, Bethesda, MD 20892
| | - Hassan Saadi
- Secretory Physiology Section, National Institute of Dental and Craniofacial Research, NIH, Bethesda, MD 20892
| | - Ga-Yeon Son
- Secretory Physiology Section, National Institute of Dental and Craniofacial Research, NIH, Bethesda, MD 20892
| | - Zahra Shokatian
- Secretory Physiology Section, National Institute of Dental and Craniofacial Research, NIH, Bethesda, MD 20892
| | - Lara E Terry
- Department of Pharmacology and Physiology, University of Rochester, Rochester, NY 14526
| | - Mohamed Trebak
- Department of Pharmacology and Chemical Biology, Vascular Medicine Institute, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
| | - David I Yule
- Department of Pharmacology and Physiology, University of Rochester, Rochester, NY 14526
| | - Indu Ambudkar
- Secretory Physiology Section, National Institute of Dental and Craniofacial Research, NIH, Bethesda, MD 20892;
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de Souza LB, Ong HL, Liu X, Ambudkar IS. PIP 2 and septin control STIM1/Orai1 assembly by regulating cytoskeletal remodeling via a CDC42-WASP/WAVE-ARP2/3 protein complex. Cell Calcium 2021; 99:102475. [PMID: 34601312 DOI: 10.1016/j.ceca.2021.102475] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 09/08/2021] [Accepted: 09/11/2021] [Indexed: 12/20/2022]
Abstract
Store-operated calcium entry (SOCE) is triggered by assembly of Orai1 with STIM proteins in ER-PM junctions. Plasma membrane PIP2 as well as PIP2-binding protein, SEPT4, significantly impact Orai1-STIM1 interaction. While septins and PIP2 can organize the actin cytoskeleton, it is unclear whether the status of actin within the junctions contributes to SOCE. We report herein that actin remodeling modulates STIM1 clustering. Our findings show that a PIP2- and SEPT4-dependent mechanism involving CDC42, WASP/WAVE, and ARP2 regulates actin remodeling into a ring-like structure around STIM1 puncta. CDC42 localization in the ER-plasma membrane region is enhanced following ER-Ca2+ store depletion. PIP2 depletion or knockdown of SEPT4 attenuate the recruitment of CDC42 to the ER-PM region. Importantly, knockdown of SEPT4, or CDC42+ARP2, disrupts the organization of actin as well as STIM1 clustering. Consequently, Orai1 recruitment to STIM1 puncta, SOCE, and NFAT translocation to the nucleus are all attenuated. Ca2+ influx induced by STIM1-C terminus is not affected by CDC42 knockdown. In aggregate, our findings reveal that PIP2 and SEPT4 affect Orai1/STIM1 clustering by coordinating actin remodeling within ER-PM junctions. This dynamic reorganization of actin has an important role in regulation of SOCE and downstream Ca2+-dependent effector functions.
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Affiliation(s)
- Lorena Brito de Souza
- Secretory Physiology Section, NIDCR, NIH, Bldg. 10/Room 1N-113, Bethesda, MD 20892, USA
| | - Hwei Ling Ong
- Secretory Physiology Section, NIDCR, NIH, Bldg. 10/Room 1N-113, Bethesda, MD 20892, USA.
| | - Xibao Liu
- Secretory Physiology Section, NIDCR, NIH, Bldg. 10/Room 1N-113, Bethesda, MD 20892, USA
| | - Indu S Ambudkar
- Secretory Physiology Section, NIDCR, NIH, Bldg. 10/Room 1N-113, Bethesda, MD 20892, USA.
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Filho EGF, da Silva EZM, Ong HL, Swaim WD, Ambudkar IS, Oliver C, Jamur MC. RACK1 plays a critical role in mast cell secretion and Ca2+ mobilization by modulating F-actin dynamics. J Cell Sci 2021; 134:263932. [PMID: 34550354 DOI: 10.1242/jcs.252585] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Accepted: 03/15/2021] [Indexed: 11/20/2022] Open
Abstract
Although RACK1 is known to act as a signaling hub in immune cells, its presence and role in mast cells (MCs) is undetermined. MC activation via antigen stimulation results in mediator release and is preceded by cytoskeleton reorganization and Ca2+ mobilization. In this study, we found that RACK1 was distributed throughout the MC cytoplasm both in vivo and in vitro. After RACK1 knockdown (KD), MCs were rounded, and the cortical F-actin was fragmented. Following antigen stimulation, in RACK1 KD MCs, there was a reduction in cortical F-actin, an increase in monomeric G-actin and a failure to organize F-actin. RACK1 KD also increased and accelerated degranulation. CD63+ secretory granules were localized in F-actin-free cortical regions in non-stimulated RACK1 KD MCs. Additionally, RACK1 KD increased antigen-stimulated Ca2+ mobilization, but attenuated antigen-stimulated depletion of ER Ca2+ stores and thapsigargin-induced Ca2+ entry. Following MC activation there was also an increase in interaction of RACK1 with Orai1 Ca2+-channels, β-actin and the actin-binding proteins vinculin and MyoVa. These results show that RACK1 is a critical regulator of actin dynamics, affecting mediator secretion and Ca2+ signaling in MCs. This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Edismauro G Freitas Filho
- Department of Cell and Molecular Biology and Pathogenic Bioagents, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, Av. Bandeirantes 3900, Ribeirão Preto, SP 14049-900, Brazil
| | - Elaine Z M da Silva
- Department of Cell and Molecular Biology and Pathogenic Bioagents, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, Av. Bandeirantes 3900, Ribeirão Preto, SP 14049-900, Brazil
| | - Hwei Ling Ong
- Secretory Physiology Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD 20892, USA
| | - William D Swaim
- Secretory Physiology Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD 20892, USA
| | - Indu S Ambudkar
- Secretory Physiology Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD 20892, USA
| | - Constance Oliver
- Department of Cell and Molecular Biology and Pathogenic Bioagents, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, Av. Bandeirantes 3900, Ribeirão Preto, SP 14049-900, Brazil
| | - Maria Célia Jamur
- Department of Cell and Molecular Biology and Pathogenic Bioagents, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, Av. Bandeirantes 3900, Ribeirão Preto, SP 14049-900, Brazil
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Shah SI, Ong HL, Demuro A, Ullah G. PunctaSpecks: A tool for automated detection, tracking, and analysis of multiple types of fluorescently labeled biomolecules. Cell Calcium 2020; 89:102224. [PMID: 32502904 PMCID: PMC7343294 DOI: 10.1016/j.ceca.2020.102224] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Revised: 05/12/2020] [Accepted: 05/21/2020] [Indexed: 01/21/2023]
Abstract
Recent advances in imaging technology and fluorescent probes have made it possible to gain information about the dynamics of subcellular processes at unprecedented spatiotemporal scales. Unfortunately, a lack of automated tools to efficiently process the resulting imaging data encoding fine details of the biological processes remains a major bottleneck in utilizing the full potential of these powerful experimental techniques. Here we present a computational tool, called PunctaSpecks, that can characterize fluorescence signals arising from a wide range of biological molecules under normal and pathological conditions. Among other things, the program can calculate the number, areas, life-times, and amplitudes of fluorescence signals arising from multiple sources, track diffusing fluorescence sources like moving mitochondria, and determine the overlap probability of two processes or organelles imaged using indicator dyes of different colors. We have tested PunctaSpecks on synthetic time-lapse movies containing mobile fluorescence objects of various sizes, mimicking the activity of biomolecules. The robustness of the software is tested by varying the level of noise along with random but known pattern of appearing, disappearing, and movement of these objects. Next, we use PunctaSpecks to characterize protein-protein interaction involved in store-operated Ca2+ entry through the formation and activation of plasma membrane-bound ORAI1 channel and endoplasmic reticulum membrane-bound stromal interaction molecule (STIM), the evolution of inositol 1,4,5-trisphosphate (IP3)-induced Ca2+ signals from sub-micrometer size local events into global waves in human cortical neurons, and the activity of Alzheimer's disease-associated β amyloid pores in the plasma membrane. The tool can also be used to study other dynamical processes imaged through fluorescence molecules. The open source algorithm allows for extending the program to analyze more than two types of biomolecules visualized using markers of different colors.
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Affiliation(s)
| | - Hwei Ling Ong
- Secretory Physiology Section, NIDCR, NIH, Bethesda, MD, 20892,USA
| | - Angelo Demuro
- Department of Neurobiology and Behavior, University of California, Irvine, CA 92697, USA
| | - Ghanim Ullah
- Department of Physics, University of South Florida, Tampa, FL 33647, USA.
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Shrestha N, Bacsa B, Ong HL, Scheruebel S, Bischof H, Malli R, Ambudkar IS, Groschner K. TRIC-A shapes oscillatory Ca2+ signals by interaction with STIM1/Orai1 complexes. PLoS Biol 2020; 18:e3000700. [PMID: 32330125 PMCID: PMC7202670 DOI: 10.1371/journal.pbio.3000700] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Revised: 05/06/2020] [Accepted: 04/09/2020] [Indexed: 01/08/2023] Open
Abstract
Trimeric intracellular cation (TRIC) channels have been proposed to modulate Ca2+ release from the endoplasmic reticulum (ER) and determine oscillatory Ca2+ signals. Here, we report that TRIC-A-mediated amplitude and frequency modulation of ryanodine receptor 2 (RyR2)-mediated Ca2+ oscillations and inositol 1,4,5-triphosphate receptor (IP3R)-induced cytosolic signals is based on attenuating store-operated Ca2+ entry (SOCE). Further, TRIC-A-dependent delay in ER Ca2+ store refilling contributes to shaping the pattern of Ca2+ oscillations. Upon ER Ca2+ depletion, TRIC-A clusters with stromal interaction molecule 1 (STIM1) and Ca2+-release-activated Ca2+ channel 1 (Orai1) within ER-plasma membrane (PM) junctions and impairs assembly of the STIM1/Orai1 complex, causing a decrease in Orai1-mediated Ca2+ current and SOCE. Together, our findings demonstrate that TRIC-A is a negative regulator of STIM1/Orai1 function. Thus, aberrant SOCE could contribute to muscle disorders associated with loss of TRIC-A.
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Affiliation(s)
- Niroj Shrestha
- Gottfried Schatz Research Center-Biophysics, Medical University of Graz, Graz, Austria
| | - Bernadett Bacsa
- Gottfried Schatz Research Center-Biophysics, Medical University of Graz, Graz, Austria
| | - Hwei Ling Ong
- Secretory Physiology Section, NIDCR, NIH, Bethesda, Maryland, United States of America
| | - Susanne Scheruebel
- Gottfried Schatz Research Center-Biophysics, Medical University of Graz, Graz, Austria
| | - Helmut Bischof
- Gottfried Schatz Research Center-Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
| | - Roland Malli
- Gottfried Schatz Research Center-Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
| | - Indu Suresh Ambudkar
- Secretory Physiology Section, NIDCR, NIH, Bethesda, Maryland, United States of America
| | - Klaus Groschner
- Gottfried Schatz Research Center-Biophysics, Medical University of Graz, Graz, Austria
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Ong HL, Ambudkar IS. The Endoplasmic Reticulum-Plasma Membrane Junction: A Hub for Agonist Regulation of Ca 2+ Entry. Cold Spring Harb Perspect Biol 2020; 12:cshperspect.a035253. [PMID: 31501196 DOI: 10.1101/cshperspect.a035253] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Stimulation of cell-surface receptors induces cytosolic Ca2+ ([Ca2+]i) increases that are detected and transduced by effector proteins for regulation of cell function. Intracellular Ca2+ release, via endoplasmic reticulum (ER) proteins inositol 1,4,5-trisphosphate receptors (IP3R) and ryanodine receptors (RyR), and Ca2+ influx, via store-operated Ca2+ entry (SOCE), contribute to the increase in [Ca2+]i The amplitude, frequency, and spatial characteristics of the [Ca2+]i increases are controlled by the compartmentalization of proteins into signaling complexes such as receptor-signaling complexes and SOCE complexes. Both complexes include protein and lipid components, located in the plasma membrane (PM) and ER. Receptor signaling initiates in the PM via phospholipase C (PLC)-mediated hydrolysis of phosphatidylinositol 4,5-bisphosphate (PIP2), and culminates with the activation of IP3R in the ER. Conversely, SOCE is initiated in the ER by Ca2+-sensing stromal interaction molecule (STIM) proteins, which then interact with PM channels Orai1 and TRPC1 to activate Ca2+ entry. This review will address how ER-PM junctions serve a central role in agonist regulation of SOCE.
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Affiliation(s)
- Hwei Ling Ong
- Secretory Physiology Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda Maryland 20892
| | - Indu Suresh Ambudkar
- Secretory Physiology Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda Maryland 20892
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Subedi KP, Ong HL, Son GY, Liu X, Ambudkar IS. STIM2 Induces Activated Conformation of STIM1 to Control Orai1 Function in ER-PM Junctions. Cell Rep 2018; 23:522-534. [DOI: 10.1016/j.celrep.2018.03.065] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Revised: 02/12/2018] [Accepted: 03/15/2018] [Indexed: 02/07/2023] Open
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Liu X, Gong B, de Souza LB, Ong HL, Subedi KP, Cheng KT, Swaim W, Zheng C, Mori Y, Ambudkar IS. Radiation inhibits salivary gland function by promoting STIM1 cleavage by caspase-3 and loss of SOCE through a TRPM2-dependent pathway. Sci Signal 2017; 10:10/482/eaal4064. [PMID: 28588080 DOI: 10.1126/scisignal.aal4064] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Store-operated Ca2+ entry (SOCE) is critical for salivary gland fluid secretion. We report that radiation treatment caused persistent salivary gland dysfunction by activating a TRPM2-dependent mitochondrial pathway, leading to caspase-3-mediated cleavage of stromal interaction molecule 1 (STIM1) and loss of SOCE. After irradiation, acinar cells from the submandibular glands of TRPM2+/+ , but not those from TRPM2-/- mice, displayed an increase in the concentrations of mitochondrial Ca2+ and reactive oxygen species, a decrease in mitochondrial membrane potential, and activation of caspase-3, which was associated with a sustained decrease in STIM1 abundance and attenuation of SOCE. In a salivary gland cell line, silencing the mitochondrial Ca2+ uniporter or caspase-3 or treatment with inhibitors of TRPM2 or caspase-3 prevented irradiation-induced loss of STIM1 and SOCE. Expression of exogenous STIM1 in the salivary glands of irradiated mice increased SOCE and fluid secretion. We suggest that targeting the mechanisms underlying the loss of STIM1 would be a potentially useful approach for preserving salivary gland function after radiation therapy.
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Affiliation(s)
- Xibao Liu
- Molecular Physiology and Therapeutics Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD 20892, USA
| | - Baijuan Gong
- Department of Orthodontics, Jilin University School of Stomatology, Changchun 130021, People's Republic of China
| | - Lorena Brito de Souza
- Molecular Physiology and Therapeutics Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD 20892, USA
| | - Hwei Ling Ong
- Molecular Physiology and Therapeutics Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD 20892, USA
| | - Krishna P Subedi
- Molecular Physiology and Therapeutics Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD 20892, USA
| | - Kwong Tai Cheng
- Molecular Physiology and Therapeutics Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD 20892, USA
| | - William Swaim
- Molecular Physiology and Therapeutics Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD 20892, USA
| | - Changyu Zheng
- Molecular Physiology and Therapeutics Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD 20892, USA
| | - Yasuo Mori
- Laboratory of Molecular Biology, Department of Synthetic and Biological Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan
| | - Indu S Ambudkar
- Molecular Physiology and Therapeutics Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD 20892, USA.
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Abstract
Store-operated calcium entry (SOCE) is a ubiquitous Ca2+ entry pathway that is activated in response to depletion of ER-Ca2+ stores and critically controls the regulation of physiological functions in miscellaneous cell types. The transient receptor potential canonical 1 (TRPC1) is the first member of the TRPC channel subfamily to be identified as a molecular component of SOCE. While TRPC1 has been shown to contribute to SOCE and regulate various functions in many cells, none of the reported TRPC1-mediated currents resembled ICRAC, the highly Ca2+-selective store-dependent current first identified in lymphocytes and mast cells. Almost a decade after the cloning of TRPC1 two proteins were identified as the primary components of the CRAC channel. The first, STIM1, is an ER-Ca2+ sensor protein involved in activating SOCE. The second, Orai1 is the pore-forming component of the CRAC channel. Co-expression of STIM1 and Orai1 generated robust ICRAC. Importantly, STIM1 was shown to also activate TRPC1 via its C-terminal polybasic domain, which is distinct from its Orai1-activating domain, SOAR. In addition, TRPC1 function critically depends on Orai1-mediated Ca2+ entry which triggers recruitment of TRPC1 into the plasma membrane where it is then activated by STIM1. TRPC1 and Orai1 form discrete STIM1-gated channels that generate distinct Ca2+ signals and regulate specific cellular functions. Surface expression of TRPC1 can be modulated by trafficking of the channel to and from the plasma membrane, resulting in changes to the phenotype of TRPC1-mediated current and [Ca2+]i signals. Thus, TRPC1 is activated downstream of Orai1 and modifies the initial [Ca2+]i signal generated by Orai1 following store depletion. This review will summarize the important findings that underlie the current concepts for activation and regulation of TRPC1, as well as its impact on cell function.
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Affiliation(s)
- Indu S Ambudkar
- Secretory Physiology Section, Molecular Physiology and Therapeutics Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD 20892, USA.
| | - Lorena Brito de Souza
- Secretory Physiology Section, Molecular Physiology and Therapeutics Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD 20892, USA
| | - Hwei Ling Ong
- Secretory Physiology Section, Molecular Physiology and Therapeutics Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD 20892, USA
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Abstract
Store-operated calcium entry (SOCE), a unique plasma membrane Ca2+ entry mechanism, is activated when ER-[Ca2+] is decreased. SOCE is mediated via the primary channel, Orai1, as well as others such as TRPC1. STIM1 and STIM2 are ER-Ca2+ sensor proteins that regulate Orai1 and TRPC1. SOCE requires assembly of STIM proteins with the plasma membrane channels which occurs within distinct regions in the cell that have been termed as endoplasmic reticulum (ER)-plasma membrane (PM) junctions. The PM and ER are in close proximity to each other within this region, which allows STIM1 in the ER to interact with and activate either Orai1 or TRPC1 in the plasma membrane. Activation and regulation of SOCE involves dynamic assembly of various components that are involved in mediating Ca2+ entry as well as those that determine the formation and stabilization of the junctions. These components include proteins in the cytosol, ER and PM, as well as lipids in the PM. Recent studies have also suggested that SOCE and its components are compartmentalized within ER-PM junctions and that this process might require remodeling of the plasma membrane lipids and reorganization of structural and scaffolding proteins. Such compartmentalization leads to the generation of spatially- and temporally-controlled Ca2+signals that are critical for regulating many downstream cellular functions.
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Affiliation(s)
- Krishna P Subedi
- Secretory Physiology Section, Molecular Physiology and Therapeutics Branch, NIDCR, NIH, Bethesda, MD, USA
| | - Hwei Ling Ong
- Secretory Physiology Section, Molecular Physiology and Therapeutics Branch, NIDCR, NIH, Bethesda, MD, USA
| | - Indu S Ambudkar
- Secretory Physiology Section, Molecular Physiology and Therapeutics Branch, NIDCR, NIH, Bethesda, MD, USA.
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Jang SI, Ong HL, Liu X, Alevizos I, Ambudkar IS. Up-regulation of Store-operated Ca2+ Entry and Nuclear Factor of Activated T Cells Promote the Acinar Phenotype of the Primary Human Salivary Gland Cells. J Biol Chem 2016; 291:8709-20. [PMID: 26903518 DOI: 10.1074/jbc.m115.701607] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Indexed: 01/12/2023] Open
Abstract
The signaling pathways involved in the generation and maintenance of exocrine gland acinar cells have not yet been established. Primary human salivary gland epithelial cells, derived from salivary gland biopsies, acquired an acinar-like phenotype when the [Ca(2+)] in the serum-free medium (keratinocyte growth medium, KGM) was increased from 0.05 mm (KGM-L) to 1.2 mm (KGM-H). Here we examined the mechanism underlying this Ca(2+)-dependent generation of the acinar cell phenotype. Compared with cells in KGM-L, those in KGM-H display enhancement of Orai1, STIM1, STIM2, and nuclear factor of activated T cells 1 (NFAT1) expression together with an increase in store-operated Ca(2+) entry (SOCE), SOCE-dependent nuclear translocation of pGFP-NFAT1, and NFAT-dependent but not NFκB-dependent gene expression. Importantly, AQP5, an acinar-specific protein critical for function, is up-regulated in KGM-H via SOCE/NFAT-dependent gene expression. We identified critical NFAT binding motifs in the AQP5 promoter that are involved in Ca(2+)-dependent up-regulation of AQP5. These important findings reveal that the Ca(2+)-induced switch of salivary epithelial cells to an acinar-like phenotype involves remodeling of SOCE and NFAT signaling, which together control the expression of proteins critically relevant for acinar cell function. Our data provide a novel strategy for generating and maintaining acinar cells in culture.
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Affiliation(s)
- Shyh-Ing Jang
- Sjögren's Syndrome and Salivary Gland Dysfunction Unit, Molecular Physiology and Therapeutics Branch, NIDCR/National Institutes of Health, Bethesda, Maryland 20892
| | | | - Xibao Liu
- From the Secretory and Physiology Section and
| | - Ilias Alevizos
- Sjögren's Syndrome and Salivary Gland Dysfunction Unit, Molecular Physiology and Therapeutics Branch, NIDCR/National Institutes of Health, Bethesda, Maryland 20892
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15
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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] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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16
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Ong HL, Chang SHS, Abdin E, Vaingankar JA, Jeyagurunathan A, Shafie S, Magadi H, Chong SA, Subramaniam M. Association of Grip Strength, Upper Arm Circumference, and Waist Circumference with Dementia in Older Adults of the WiSE Study: A Cross-Sectional Analysis. J Nutr Health Aging 2016; 20:996-1001. [PMID: 27925139 DOI: 10.1007/s12603-015-0643-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVE We examined the associations of handgrip strength, upper arm circumference, and waist circumference with dementia among Singapore older adults. DESIGN Cross-sectional epidemiological study. SETTING Residential homes, day care centres, nursing homes and institutions. PARTICIPANTS 2,565 men and women aged 60 years and above who participated in the Well-being of the Singapore Elderly (WiSE) study in 2013. MEASUREMENTS Socio-demographic correlates, dietary habits, health behaviours, grip strength, upper arm circumference, and waist circumference were collected. Grip strength was measured using a hand dynamometer with the dominant hand. Upper arm circumference was measured using a measuring tape around the thickest part of the upper arm while waist circumference measured in centimetres was measured at the narrowest part of the body between the chest and hips for women, and measured at the level of the umbilicus for men. Dementia was diagnosed using the 10/66 dementia diagnostic criteria. RESULTS Mean grip strength was 13.07 kg (SE=0.60) for people with dementia and 21.98 kg (SE=0.26) for people without dementia. After adjusting for all factors, grip strength remained significantly associated with dementia (p <0.0001). Upper arm circumference was associated with dementia (p <0.0001) but this association was only significant in the univariate analysis. Waist circumference was not significantly associated with dementia. CONCLUSIONS Lower grip strength was independently associated with dementia in the older adult population in Singapore. Further research needs to be done to ascertain whether this association exists for specific types of dementia and look into the relationship of other anthropometric measurements with dementia in Singapore.
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Affiliation(s)
- H L Ong
- Hui Lin Ong, Research Division, Institute of Mental Health, Buangkok Green Medical Park, 10 Buangkok View, Singapore 539747, Singapore.
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de Souza LB, Ong HL, Liu X, Ambudkar IS. Fast endocytic recycling determines TRPC1–STIM1 clustering in ER–PM junctions and plasma membrane function of the channel. Biochimica et Biophysica Acta (BBA) - Molecular Cell Research 2015; 1853:2709-21. [DOI: 10.1016/j.bbamcr.2015.07.019] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Revised: 07/24/2015] [Accepted: 07/28/2015] [Indexed: 12/27/2022]
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Ong HL, Ambudkar IS. Molecular determinants of TRPC1 regulation within ER–PM junctions. Cell Calcium 2015; 58:376-86. [DOI: 10.1016/j.ceca.2015.03.008] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2015] [Revised: 03/18/2015] [Accepted: 03/19/2015] [Indexed: 11/30/2022]
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Ong HL, de Souza LB, Zheng C, Cheng KT, Liu X, Goldsmith CM, Feske S, Ambudkar IS. STIM2 enhances receptor-stimulated Ca²⁺ signaling by promoting recruitment of STIM1 to the endoplasmic reticulum-plasma membrane junctions. Sci Signal 2015; 8:ra3. [PMID: 25587190 DOI: 10.1126/scisignal.2005748] [Citation(s) in RCA: 77] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
A central component of receptor-evoked Ca(2+) signaling is store-operated Ca(2+) entry (SOCE), which is activated by the assembly of STIM1-Orai1 channels in endoplasmic reticulum (ER) and plasma membrane (PM) (ER-PM) junctions in response to depletion of ER Ca(2+). We report that STIM2 enhances agonist-mediated activation of SOCE by promoting STIM1 clustering in ER-PM junctions at low stimulus intensities. Targeted deletion of STIM2 in mouse salivary glands diminished fluid secretion in vivo and SOCE activation in dispersed salivary acinar cells stimulated with low concentrations of muscarinic receptor agonists. STIM2 knockdown in human embryonic kidney (HEK) 293 cells diminished agonist-induced Ca(2+) signaling and nuclear translocation of NFAT (nuclear factor of activated T cells). STIM2 lacking five carboxyl-terminal amino acid residues did not promote formation of STIM1 puncta at low concentrations of agonist, whereas coexpression of STIM2 with STIM1 mutant lacking the polybasic region STIM1ΔK resulted in co-clustering of both proteins. Together, our findings suggest that STIM2 recruits STIM1 to ER-PM junctions at low stimulus intensities when ER Ca(2+) stores are mildly depleted, thus increasing the sensitivity of Ca(2+) signaling to agonists.
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Affiliation(s)
- Hwei Ling Ong
- Secretory Physiology Section, Molecular Physiology and Therapeutics Branch, National Institute of Dental and Craniofacial Research (NIDCR), National Institutes of Health (NIH), Bethesda, MD 20892, USA
| | - Lorena Brito de Souza
- Secretory Physiology Section, Molecular Physiology and Therapeutics Branch, National Institute of Dental and Craniofacial Research (NIDCR), National Institutes of Health (NIH), Bethesda, MD 20892, USA
| | - Changyu Zheng
- Translational Research Core, Molecular Physiology and Therapeutics Branch, NIDCR, NIH, Bethesda, MD 20892, USA
| | - Kwong Tai Cheng
- Department of Pharmacology, College of Medicine, University of Illinois at Chicago, Chicago, IL 60612, USA
| | - Xibao Liu
- Secretory Physiology Section, Molecular Physiology and Therapeutics Branch, National Institute of Dental and Craniofacial Research (NIDCR), National Institutes of Health (NIH), Bethesda, MD 20892, USA
| | - Corinne M Goldsmith
- Translational Research Core, Molecular Physiology and Therapeutics Branch, NIDCR, NIH, Bethesda, MD 20892, USA
| | - Stefan Feske
- Department of Pathology, New York University Langone Medical Center, New York, NY 10016, USA
| | - Indu S Ambudkar
- Secretory Physiology Section, Molecular Physiology and Therapeutics Branch, National Institute of Dental and Craniofacial Research (NIDCR), National Institutes of Health (NIH), Bethesda, MD 20892, USA.
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Liu X, Gong B, Ong HL, Cheng KT, Muniswamy M, Ambudkar IS. Role of Mitochondrial Ca2+ Uniporter in Radiation-Induced Cell Damage. Biophys J 2015. [DOI: 10.1016/j.bpj.2014.11.615] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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de Souza L, Lockwich T, Ong HL, Cheng KT, Ambudkar IS. Remodeling of the Cytoskeleton and Regulation of Store-Operated Calcium Entry. Biophys J 2015. [DOI: 10.1016/j.bpj.2014.11.3098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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Subedi K, Ong HL, Ambudkar I. STIM1-STIM2 Interactions Modulate Store-Operated Calcium Entry. Biophys J 2015. [DOI: 10.1016/j.bpj.2014.11.3097] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
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Jang SI, Ong HL, Gallo A, Liu X, Illei G, Alevizos I. Establishment of functional acinar-like cultures from human salivary glands. J Dent Res 2014; 94:304-11. [PMID: 25416669 DOI: 10.1177/0022034514559251] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Disorders of human salivary glands resulting from therapeutic radiation treatment for head and neck cancers or from the autoimmune disease Sjögren syndrome (SS) frequently result in the reduction or complete loss of saliva secretion. Such irreversible dysfunction of the salivary glands is due to the impairment of acinar cells, the major glandular cells of protein, salt secretion, and fluid movement. Availability of primary epithelial cells from human salivary gland tissue is critical for studying the underlying mechanisms of these irreversible disorders. We applied 2 culture system techniques on human minor salivary gland epithelial cells (phmSG) and optimized the growth conditions to achieve the maintenance of phmSG in an acinar-like phenotype. These phmSG cells exhibited progenitor cell markers (keratin 5 and nanog) as well as acinar-specific markers-namely, α-amylase, cystatin C, TMEM16A, and NKCC1. Importantly, with an increase of the calcium concentration in the growth medium, these phmSG cells were further promoted to acinar-like cells in vitro, as indicated by an increase in AQP5 expression. In addition, these phmSG cells also demonstrated functional calcium mobilization, formation of epithelial monolayer with high transepithelial electrical resistance (TER), and polarized secretion of α-amylase secretion after β-adrenergic receptor stimulation. Taken together, suitable growth conditions have been established to isolate and support culture of acinar-like cells from the human salivary gland. These primary epithelial cells can be useful for study of molecular mechanisms involved in regulating the function of acinar cells and in the loss of salivary gland function in patients.
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Affiliation(s)
- S I Jang
- Sjögren's Syndrome and Salivary Gland Dysfunction Unit, Molecular Physiology and Therapeutics Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
| | - H L Ong
- Secretory and Physiology Section, Molecular Physiology and Therapeutics Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
| | - A Gallo
- Sjögren's Syndrome and Salivary Gland Dysfunction Unit, Molecular Physiology and Therapeutics Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
| | - X Liu
- Secretory and Physiology Section, Molecular Physiology and Therapeutics Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
| | - G Illei
- Sjögren's Syndrome and Salivary Gland Dysfunction Unit, Molecular Physiology and Therapeutics Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
| | - I Alevizos
- Sjögren's Syndrome and Salivary Gland Dysfunction Unit, Molecular Physiology and Therapeutics Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
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Abstract
The TRP-canonical (TRPC) subfamily, which consists of seven members (TRPC1-TRPC7), are Ca(2+)-permeable cation channels that are activated in response to receptor-mediated PIP2 hydrolysis via store-dependent and store-independent mechanisms. These channels are involved in a variety of physiological functions in different cell types and tissues. Of these, TRPC6 has been linked to a channelopathy resulting in human disease. Two key players of the store-dependent regulatory pathway, STIM1 and Orai1, interact with some TRPC channels to gate and regulate channel activity. The Ca(2+) influx mediated by TRPC channels generates distinct intracellular Ca(2+) signals that regulate downstream signaling events and consequent cell functions. This requires localization of TRPC channels in specific plasma membrane microdomains and precise regulation of channel function which is coordinated by various scaffolding, trafficking, and regulatory proteins.
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Affiliation(s)
- Hwei Ling Ong
- Secretory Physiology Section, Molecular Physiology and Therapeutics Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, 20892, USA
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Simoni F, Lucchetta DE, Lucchetti L, Ong HL, Serak SV, Tabiryan N. First-order optical Freedericksz transition in a dye-doped nematic liquid crystal. Opt Lett 2013; 38:878-880. [PMID: 23503246 DOI: 10.1364/ol.38.000878] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
A first-order optical Freedericksz transition in a nematic liquid crystal doped by a small quantity of a dichroic dye with negative dichroism is observed. The initial homeotropic state corresponds to maximum absorption for the linearly polarized incident beam, while reorientation reduces absorption increasing the optical torque: this process produces the positive feedback leading to the observed bistable behavior.
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Affiliation(s)
- F Simoni
- Dipartimento di Scienze e Ingegneria della Materia, dell'Ambiente ed Urbanistica and CNISM Università Politecnica delle Marche, Ancona, Italy.
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Ong HL, Jang SI, Ambudkar IS. Distinct contributions of Orai1 and TRPC1 to agonist-induced [Ca(2+)](i) signals determine specificity of Ca(2+)-dependent gene expression. PLoS One 2012; 7:e47146. [PMID: 23115638 PMCID: PMC3480383 DOI: 10.1371/journal.pone.0047146] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2012] [Accepted: 09/10/2012] [Indexed: 12/30/2022] Open
Abstract
Regulation of critical cellular functions, including Ca2+-dependent gene expression, is determined by the temporal and spatial aspects of agonist-induced Ca2+ signals. Stimulation of cells with physiological concentrations of agonists trigger increases [Ca2+]i due to intracellular Ca2+ release and Ca2+ influx. While Orai1-STIM1 channels account for agonist-stimulated [Ca2+]i increase as well as activation of NFAT in cells such as lymphocytes, RBL and mast cells, both Orai1-STIM1 and TRPC1-STIM1 channels contribute to [Ca2+]i increases in human submandibular gland (HSG) cells. However, only Orai1-mediated Ca2+ entry regulates the activation of NFAT in HSG cells. Since both TRPC1 and Orai1 are activated following internal Ca2+ store depletion in these cells, it is not clear how the cells decode individual Ca2+ signals generated by the two channels for the regulation of specific cellular functions. Here we have examined the contributions of Orai1 and TRPC1 to carbachol (CCh)-induced [Ca2+]i signals and activation of NFAT in single cells. We report that Orai1-mediated Ca2+ entry generates [Ca2+]i oscillations at different [CCh], ranging from very low to high. In contrast, TRPC1-mediated Ca2+ entry generates sustained [Ca2+]i elevation at high [CCh] and contributes to frequency of [Ca2+]i oscillations at lower [agonist]. More importantly, the two channels are coupled to activation of distinct Ca2+ dependent gene expression pathways, consistent with the different patterns of [Ca2+]i signals mediated by them. Nuclear translocation of NFAT and NFAT-dependent gene expression display “all-or-none” activation that is exclusively driven by local [Ca2+]i generated by Orai1, independent of global [Ca2+]i changes or TRPC1-mediated Ca2+ entry. In contrast, Ca2+ entry via TRPC1 primarily regulates NFκB-mediated gene expression. Together, these findings reveal that Orai1 and TRPC1 mediate distinct local and global Ca2+ signals following agonist stimulation of cells, which determine the functional specificity of the channels in activating different Ca2+-dependent gene expression pathways.
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Affiliation(s)
- Hwei Ling Ong
- Secretory Physiology Section, Molecular Physiology and Therapeutics Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Shyh-Ing Jang
- Secretory Physiology Section, Molecular Physiology and Therapeutics Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Indu Suresh Ambudkar
- Secretory Physiology Section, Molecular Physiology and Therapeutics Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, Maryland, United States of America
- * E-mail:
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Lodola F, Laforenza U, Bonetti E, Lim D, Dragoni S, Bottino C, Ong HL, Guerra G, Ganini C, Massa M, Manzoni M, Ambudkar IS, Genazzani AA, Rosti V, Pedrazzoli P, Tanzi F, Moccia F, Porta C. Store-operated Ca2+ entry is remodelled and controls in vitro angiogenesis in endothelial progenitor cells isolated from tumoral patients. PLoS One 2012; 7:e42541. [PMID: 23049731 PMCID: PMC3458053 DOI: 10.1371/journal.pone.0042541] [Citation(s) in RCA: 115] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2012] [Accepted: 07/09/2012] [Indexed: 01/11/2023] Open
Abstract
BACKGROUND Endothelial progenitor cells (EPCs) may be recruited from bone marrow to sustain tumor vascularisation and promote the metastatic switch. Understanding the molecular mechanisms driving EPC proliferation and tubulogenesis could outline novel targets for alternative anti-angiogenic treatments. Store-operated Ca(2+) entry (SOCE), which is activated by a depletion of the intracellular Ca(2+) pool, regulates the growth of human EPCs, where is mediated by the interaction between the endoplasmic reticulum Ca(2+)-sensor, Stim1, and the plasmalemmal Ca(2+) channel, Orai1. As oncogenesis may be associated to the capability of tumor cells to grow independently on Ca(2+) influx, it is important to assess whether SOCE regulates EPC-dependent angiogenesis also in tumor patients. METHODOLOGY/PRINCIPAL FINDINGS The present study employed Ca(2+) imaging, recombinant sub-membranal and mitochondrial aequorin, real-time polymerase chain reaction, gene silencing techniques and western blot analysis to investigate the expression and the role of SOCE in EPCs isolated from peripheral blood of patients affected by renal cellular carcinoma (RCC; RCC-EPCs) as compared to control EPCs (N-EPCs). SOCE, activated by either pharmacological (i.e. cyclopiazonic acid) or physiological (i.e. ATP) stimulation, was significantly higher in RCC-EPCs and was selectively sensitive to BTP-2, and to the trivalent cations, La(3+) and Gd(3+). Furthermore, 2-APB enhanced thapsigargin-evoked SOCE at low concentrations, whereas higher doses caused SOCE inhibition. Conversely, the anti-angiogenic drug, carboxyamidotriazole (CAI), blocked both SOCE and the intracellular Ca(2+) release. SOCE was associated to the over-expression of Orai1, Stim1, and transient receptor potential channel 1 (TRPC1) at both mRNA and protein level The intracellular Ca(2+) buffer, BAPTA, BTP-2, and CAI inhibited RCC-EPC proliferation and tubulogenesis. The genetic suppression of Stim1, Orai1, and TRPC1 blocked CPA-evoked SOCE in RCC-EPCs. CONCLUSIONS SOCE is remodelled in EPCs from RCC patients and stands out as a novel molecular target to interfere with RCC vascularisation due to its ability to control proliferation and tubulogenesis.
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Affiliation(s)
- Francesco Lodola
- Department of Biology and Biotechnology “Lazzaro Spallanzani”, University of Pavia, Pavia, Italy
| | - Umberto Laforenza
- Section of Human Physiology, Department of Molecular Medicine, University of Pavia, Pavia, Italy
| | - Elisa Bonetti
- Clinical Epidemiology Laboratory Fondazione IRCCS Policlinico San Matteo, Pavia, Italy
| | - Dmitry Lim
- Department of Pharmaceutical Sciences, University of Eastern Piedmont “Amedeo Avogadro”, Novara, Italy
| | - Silvia Dragoni
- Department of Biology and Biotechnology “Lazzaro Spallanzani”, University of Pavia, Pavia, Italy
| | - Cinzia Bottino
- Section of Human Physiology, Department of Molecular Medicine, University of Pavia, Pavia, Italy
| | - Hwei Ling Ong
- Secretory Physiology Section, Molecular Physiology and Therapeutics Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Germano Guerra
- Department of Health Sciences, University of Molise, Campobasso, Italy
| | - Carlo Ganini
- Medical Oncology IRCCS Policlinico San Matteo, Pavia, Italy
| | - Margherita Massa
- Laboratory of Biotechnology, Fondazione IRCCS Policlinico San Matteo, Pavia, Italy
| | | | - Indu S. Ambudkar
- Secretory Physiology Section, Molecular Physiology and Therapeutics Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Armando A. Genazzani
- Department of Pharmaceutical Sciences, University of Eastern Piedmont “Amedeo Avogadro”, Novara, Italy
| | - Vittorio Rosti
- Clinical Epidemiology Laboratory Fondazione IRCCS Policlinico San Matteo, Pavia, Italy
| | | | - Franco Tanzi
- Department of Biology and Biotechnology “Lazzaro Spallanzani”, University of Pavia, Pavia, Italy
| | - Francesco Moccia
- Department of Biology and Biotechnology “Lazzaro Spallanzani”, University of Pavia, Pavia, Italy
| | - Camillo Porta
- Medical Oncology IRCCS Policlinico San Matteo, Pavia, Italy
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Abstract
A rise in cytoplasmic [Ca2+] due to store-operated Ca2+ entry (SOCE) triggers a plethora of responses, both acute and long term. This leads to the important question of how this initial signal is decoded to regulate specific cellular functions. It is now clearly established that local [Ca2+] at the site of SOCE can vary significantly from the global [Ca2+] in the cytosol. Such Ca2+ microdomains are generated by the assembly of key Ca2+ signaling proteins within the domains. For example, GPCR, IP 3 receptors, TRPC3 channels, the plasma membrane Ca2+ pump and the endoplasmic reticulum (ER) Ca2+ pump have all been found to be assembled in a complex and all of them contribute to the Ca2+ signal. Recent studies have revealed that two other critical components of SOCE, STIM1 and Orai1, are also recruited to these regions. Thus, the entire machinery for activation and regulation of SOCE is compartmentalized in specific cellular domains which facilitates the specificity and rate of protein-protein interactions that are required for activation of the channels. In the case of TRPC1-SOC channels, it appears that specific lipid domains, lipid raft domains (LRDs), in the plasma membrane, as well as cholesterol-binding scaffolding proteins such as caveolin-1 (Cav-1), are involved in assembly of the TRPC channel complexes. Thus, plasma membrane proteins and lipid domains as well as ER proteins contribute to the SOCE-Ca2+ signaling microdomain and modulation of the Ca2+ signals per se. Of further interest is that modulation of Ca2+ signals, i.e. amplitude and/or frequency, can result in regulation of specific cellular functions. The emerging data reveal a dynamic Ca2+ signaling complex composed of TRPC1/Orai1/STIM1 that is physiologically consistent with the dynamic nature of the Ca2+ signal that is generated. This review will focus on the recent studies which demonstrate critical aspects of the TRPC1 channelosome that are involved in the regulation of TRPC1 function and TRPC1-SOC-generated Ca2+ signals.
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Affiliation(s)
- Hwei Ling Ong
- Secretory Physiology Section, Molecular Physiology and Therapeutics Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
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Fiorio Pla A, Ong HL, Cheng KT, Brossa A, Bussolati B, Lockwich T, Paria B, Munaron L, Ambudkar IS. TRPV4 mediates tumor-derived endothelial cell migration via arachidonic acid-activated actin remodeling. Oncogene 2011; 31:200-12. [PMID: 21685934 DOI: 10.1038/onc.2011.231] [Citation(s) in RCA: 130] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Changes in intracellular calcium [Ca(2+)](i) levels control critical cytosolic and nuclear events that are involved in the initiation and progression of tumor angiogenesis in endothelial cells (ECs). Therefore, the mechanism(s) involved in agonist-induced Ca(2+)(i) signaling is a potentially important molecular target for controlling angiogenesis and tumor growth. Several studies have shown that blood vessels in tumors differ from normal vessels in their morphology, blood flow and permeability. We had previously reported a key role for arachidonic acid (AA)-mediated Ca(2+) entry in the initial stages of tumor angiogenesis in vitro. In this study we assessed the mechanism involved in AA-induced EC migration. We report that TRPV4, an AA-activated channel, is differentially expressed in EC derived from human breast carcinomas (BTEC) as compared with 'normal' EC (HMVEC). BTEC display a significant increase in TRPV4 expression, which was correlated with greater Ca(2+) entry, induced by AA or 4αPDD (a selective TRPV4 agonist) in the tumor-derived ECs. Wound-healing assays revealed a key role of TRPV4 in regulating cell migration of BTEC but not HMVEC. Knockdown of TRPV4 expression completely abolished AA-induced BTEC migration, suggesting that TRPV4 mediates the pro-angiogenic effects promoted by AA. Furthermore, pre-incubation of BTEC with AA induced actin remodeling and a subsequent increase in the surface expression of TRPV4. This was consistent with the increased plasma membrane localization of TRPV4 and higher AA-stimulated Ca(2+) entry in the migrating cells. Together, the data presented herein demonstrate that: (1) TRPV4 is differentially expressed in tumor-derived versus 'normal' EC; (2) TRPV4 has a critical role in the migration of tumor-derived but not 'normal' EC migration; and (3) AA induces actin remodeling in BTEC, resulting in a corresponding increase of TRPV4 expression in the plasma membrane. We suggest that the latter is critical for migration of EC and thus in promoting angiogenesis and tumor growth.
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Affiliation(s)
- A Fiorio Pla
- Department of Animal and Human Biology, University of Torino, Torino, Italy.
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Cheng KT, Liu X, Ong HL, Swaim W, Ambudkar IS. Local Ca²+ entry via Orai1 regulates plasma membrane recruitment of TRPC1 and controls cytosolic Ca²+ signals required for specific cell functions. PLoS Biol 2011; 9:e1001025. [PMID: 21408196 PMCID: PMC3050638 DOI: 10.1371/journal.pbio.1001025] [Citation(s) in RCA: 196] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2010] [Accepted: 01/27/2011] [Indexed: 11/18/2022] Open
Abstract
Store-operated Ca2+ entry (SOCE) has been associated with two types of channels: CRAC channels that require Orai1 and STIM1 and SOC channels that involve TRPC1, Orai1, and STIM1. While TRPC1 significantly contributes to SOCE and SOC channel activity, abrogation of Orai1 function eliminates SOCE and activation of TRPC1. The critical role of Orai1 in activation of TRPC1-SOC channels following Ca2+ store depletion has not yet been established. Herein we report that TRPC1 and Orai1 are components of distinct channels. We show that TRPC1/Orai1/STIM1-dependent ISOC, activated in response to Ca2+ store depletion, is composed of TRPC1/STIM1-mediated non-selective cation current and Orai1/STIM1-mediated ICRAC; the latter is detected when TRPC1 function is suppressed by expression of shTRPC1 or a STIM1 mutant that lacks TRPC1 gating, STIM1(684EE685). In addition to gating TRPC1 and Orai1, STIM1 mediates the recruitment and association of the channels within ER/PM junctional domains, a critical step in TRPC1 activation. Importantly, we show that Ca2+ entry via Orai1 triggers plasma membrane insertion of TRPC1, which is prevented by blocking SOCE with 1 µM Gd3+, removal of extracellular Ca2+, knockdown of Orai1, or expression of dominant negative mutant Orai1 lacking a functional pore, Orai1-E106Q. In cells expressing another pore mutant of Orai1, Orai1-E106D, TRPC1 trafficking is supported in Ca2+-containing, but not Ca2+-free, medium. Consistent with this, ICRAC is activated in cells pretreated with thapsigargin in Ca2+-free medium while ISOC is activated in cells pretreated in Ca2+-containing medium. Significantly, TRPC1 function is required for sustained KCa activity and contributes to NFκB activation while Orai1 is sufficient for NFAT activation. Together, these findings reveal an as-yet unidentified function for Orai1 that explains the critical requirement of the channel in the activation of TRPC1 following Ca2+ store depletion. We suggest that coordinated regulation of the surface expression of TRPC1 by Orai1 and gating by STIM1 provides a mechanism for rapidly modulating and maintaining SOCE-generated Ca2+ signals. By recruiting ion channels and other signaling pathways, Orai1 and STIM1 concertedly impact a variety of critical cell functions that are initiated by SOCE. Store-operated Ca2+ entry is present in all cell types and determines sustained cytosolic [Ca2+] increases that are critical for regulating a wide variety of physiological functions. This Ca2+ entry mechanism is activated in response to depletion of Ca2+ in the endoplasmic reticulum (ER). When ER [Ca2+] is decreased, the Ca2+-sensor protein STIM1 aggregates in the ER membrane and moves to regions in the periphery of the cells where it interacts with and activates two major types of channels that contribute to store-operated Ca2+ entry: CRAC and SOC. While gating of Orai1 by STIM1 is sufficient for CRAC channel activity, both Orai1 and transient receptor potential channel 1 (TRPC1) contribute to SOC channel function. The molecular composition of SOC channels and the critical role of Orai1 in activation of TRPC1 have not yet been established. In this study, we demonstrate that TRPC1 and Orai1 are components of distinct channels, both of which are regulated by STIM1. Importantly, we show that Orai1-mediated Ca2+ entry triggers plasma membrane insertion of TRPC1 which is then gated by STIM1. Ca2+ entry via functional TRPC1-STIM1 channels provides additional increase in cytosolic [Ca2+] that is required for regulation of specific cell functions such as KCa activation. Together, our findings elucidate the critical role of Orai1 in TRPC1 channel function. We suggest that the regulation of TRPC1 trafficking provides a mechanism for rapidly modulating cytosolic [Ca2+] following Ca2+ store depletion.
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Affiliation(s)
- Kwong Tai Cheng
- Secretory Physiology Section, Molecular Physiology and Therapeutics Branch, NIDCR, NIH, Bethesda, Maryland, United States of America
| | - Xibao Liu
- Secretory Physiology Section, Molecular Physiology and Therapeutics Branch, NIDCR, NIH, Bethesda, Maryland, United States of America
| | - Hwei Ling Ong
- Secretory Physiology Section, Molecular Physiology and Therapeutics Branch, NIDCR, NIH, Bethesda, Maryland, United States of America
| | - William Swaim
- Secretory Physiology Section, Molecular Physiology and Therapeutics Branch, NIDCR, NIH, Bethesda, Maryland, United States of America
| | - Indu S. Ambudkar
- Secretory Physiology Section, Molecular Physiology and Therapeutics Branch, NIDCR, NIH, Bethesda, Maryland, United States of America
- * E-mail:
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Abstract
Store-operated Ca(2+) entry (SOCE) is activated in response to depletion of the ER-Ca(2+) stores by the ER Ca(2+) sensor protein, STIM1 which oligomerizes and moves to ER/PM junctional domains where it interacts with and activates channels involved in SOCE. Two types of channel activities have been described. I(CRAC), via Ca(2+) release-activated Ca(2+) (CRAC) channel, which displays high Ca(2+) selectivity and accounts for the SOCE and cell function in T lymphocytes, mast cells, platelets, and some types of smooth muscle and endothelial cells. Orai1 has been established as the pore-forming component of CRAC channels and interaction of Orai1 with STIM1 is sufficient for generation of the CRAC channel. Store depletion also leads to activation of relatively non-selective cation currents (referred to as I(SOC)) that contribute to SOCE in several other cell types. TRPC channels, including TRPC1, TRPC3, and TRPC4, have been proposed as possible candidate channels for this Ca(2+) influx. TRPC1 is the best characterized channel in this regard and reported to contribute to endogenous SOCE in many cells types. TRPC1-mediated Ca(2+) entry and cation current in cells stimulated with agonist or thapsigargin are inhibited by low [Gd(3+)] and 10-20 μM 2APB (conditions that block SOCE). Importantly, STIM1 also associates with and gates TRPC1 via electrostatic interaction between STIM1 ((684)KK(685)) and TRPC1 ((639)DD(640)). Further, store depletion induces dynamic recruitment of a TRPC1/STIM1/Orai1 complex and knockdown of Orai1 completely abrogates TRPC1 function. Despite these findings, there has been much debate regarding the activation of TRPC1 by store depletion as well as the role of Orai1 and STIM1 in SOC channel function. This chapter summarizes recent studies and concepts regarding the contributions of Orai1 and TRPC1 to SOCE. Major unresolved questions regarding functional interaction between Orai1 and TRPC1 as well as possible mechanisms involved in the regulation of TRPC channels by store depletion will be discussed.
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Affiliation(s)
- Kwong Tai Cheng
- Secretory Physiology Section, Molecular Physiology and Therapeutics Branch, NIDCR, NIH, Bethesda, MD 20892, USA.
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Pani B, Ong HL, Liu X, Rauser K, Ambudkar IS, Singh BB. Lipid rafts determine clustering of STIM1 in endoplasmic reticulum-plasma membrane junctions and regulation of store-operated Ca2+ entry (SOCE). J Biol Chem 2008; 283:17333-40. [PMID: 18430726 DOI: 10.1074/jbc.m800107200] [Citation(s) in RCA: 151] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Store depletion induces STIM1 to aggregate and relocate into clusters at ER-plasma membrane junctions where it functionally interacts with and activates plasma membrane channels that mediate store-operated Ca(2+) entry (SOCE). Thus, the site of peripheral STIM1 clusters is critical for the regulation of SOCE. However, what determines the location of the STIM1 clusters in the ER-PM junctional regions, and whether these represent specific sites in the cell is not yet known. Here we report that clustering of STIM1 in the subplasma membrane region of the cell and activation of TRPC1-dependent SOCE are determined by lipid raft domains (LRD). We show that store depletion increased partitioning of TRPC1 and STIM1 into plasma membrane LRD. TRPC1 and STIM1 associated with each other within the LRD, and this association was dynamically regulated by the status of the ER Ca(2+) store. Peripheral STIM1 clustering was independent of TRPC1. However, sequestration of membrane cholesterol attenuated thapsigargin-induced clustering of STIM1 as well as SOCE in HSG and HEK293 cells. Recruitment and association of STIM1 and TRPC1 in LRD was also decreased. Additionally STIM1(D76A), which is peripherally localized and constitutively activates SOCE in unstimulated cells, displayed a relatively higher partitioning into LRD and interaction with TRPC1, as compared with STIM1. Disruption of membrane rafts decreased peripheral STIM1(D76A) puncta, its association with TRPC1 and the constitutive SOCE. Together, these data demonstrate that intact LRD determine targeting of STIM1 clusters to ER-plasma membrane junctions following store depletion. This facilitates the functional interaction of STIM1 with TRPC1 and activation of SOCE.
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Affiliation(s)
- Biswaranjan Pani
- Department of Biochemistry and Molecular Biology, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, North Dakota 58201, USA
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Abstract
Orai1 and TRPC1 have been proposed as core components of store-operated calcium release-activated calcium (CRAC) and store-operated calcium (SOC) channels, respectively. STIM1, a Ca(2+) sensor protein in the endoplasmic reticulum, interacts with and mediates store-dependent regulation of both channels. We have previously reported that dynamic association of Orai1, TRPC1, and STIM1 is involved in activation of store-operated Ca(2+) entry (SOCE) in salivary gland cells. In this study, we have assessed the molecular basis of TRPC1-SOC channels in HEK293 cells. We report that TRPC1+STIM1-dependent SOCE requires functional Orai1. Thapsigargin stimulation of cells expressing Orai1+STIM1 increased Ca(2+) entry and activated typical I(CRAC) current. STIM1 alone did not affect SOCE, whereas expression of Orai1 induced a decrease. Expression of TRPC1 induced a small increase in SOCE, which was greatly enhanced by co-expression of STIM1. Thapsigargin stimulation of cells expressing TRPC1+STIM1 activated a non-selective cation current, I(SOC), that was blocked by 1 microm Gd(3+) and 2-APB. Knockdown of Orai1 decreased endogenous SOCE as well as SOCE with TRPC1 alone. siOrai1 also significantly reduced SOCE and I(SOC) in cells expressing TRPC1+STIM1. Expression of R91WOrai1 or E106QOrai1 induced similar attenuation of TRPC1+STIM1-dependent SOCE and I(SOC), whereas expression of Orai1 with TRPC1+STIM1 resulted in SOCE that was larger than that with Orai1+STIM1 or TRPC1+STIM1 but not additive. Additionally, Orai1, E106QOrai1, and R91WOrai1 co-immunoprecipitated with similar levels of TRPC1 and STIM1 from HEK293 cells, and endogenous TRPC1, STIM1, and Orai1 were co-immunoprecipitated from salivary glands. Together, these data demonstrate a functional requirement for Orai1 in TRPC1+STIM1-dependent SOCE.
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Affiliation(s)
- Kwong Tai Cheng
- Secretory Physiology Section, Molecular Physiology and Therapeutics Branch, NIDCR, National Institutes of Health, Bethesda, Maryland 20892, USA
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Ong HL, Cheng KT, Liu X, Bandyopadhyay BC, Paria BC, Soboloff J, Pani B, Gwack Y, Srikanth S, Singh BB, Gill DL, Ambudkar IS. Dynamic assembly of TRPC1-STIM1-Orai1 ternary complex is involved in store-operated calcium influx. J Biol Chem 2007. [DOI: 10.1016/s0021-9258(20)58829-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Ambudkar IS, Ong HL, Liu X, Bandyopadhyay BC, Bandyopadhyay B, Cheng KT. TRPC1: The link between functionally distinct store-operated calcium channels. Cell Calcium 2007; 42:213-23. [PMID: 17350680 DOI: 10.1016/j.ceca.2007.01.013] [Citation(s) in RCA: 155] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2007] [Revised: 01/30/2007] [Accepted: 01/31/2007] [Indexed: 10/23/2022]
Abstract
Although store-operated calcium entry (SOCE) was identified more that two decades ago, understanding the molecular mechanisms that regulate and mediate this process continue to pose a major challenge to investigators in this field. Thus, there has been major focus on determining which of the models proposed for this mechanism is valid and conclusively establishing the components of the store-operated calcium (SOC) channel(s). The transient receptor potential canonical (TRPC) proteins have been suggested as candidate components of the elusive store-operated Ca(2+) entry channel. While all TRPCs are activated in response to agonist-stimulated phosphatidylinositol 4,5, bisphosphate (PIP(2)) hydrolysis, only some display store-dependent regulation. TRPC1 is currently the strongest candidate component of SOC and is shown to contribute to SOCE in many cell types. Heteromeric interactions of TRPC1 with other TRPCs generate diverse SOC channels. Recent studies have revealed novel components of SOCE, namely the stromal interacting molecule (STIM) and Orai proteins. While STIM1 has been suggested to be the ER-Ca(2+) sensor protein relaying the signal to the plasma membrane for activation of SOCE, Orai1 is reported to be the pore-forming component of CRAC channel that mediates SOCE in T-lymphocytes and other hematopoetic cells. Several studies now demonstrate that TRPC1 also associates with STIM1 suggesting that SOC and CRAC channels are regulated by similar molecular components. Interestingly, TRPC1 is also associated with Orai1 and a TRPC1-Orai1-STIM1 ternary complex contributes to SOC channel function. This review will focus on the diverse SOC channels formed by TRPC1 and the suggestion that TRPC1 might serve as a molecular link that determines their regulation by store-depletion.
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Affiliation(s)
- Indu S Ambudkar
- Secretory Physiology Section, GTTB, NIDCR, NIH, Bethesda, MD 20892, USA.
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Abstract
TRPC proteins constitute a family of conserved Ca2+-permeable cation channels which are activated in response to agonist-stimulated PIP2 hydrolysis. These channels were initially proposed to be components of the store-operated calcium entry channel (SOC). Subsequent studies have provided substantial evidence that some TRPCs contribute to SOC activity. TRPC proteins have also been shown to form agonist-stimulated calcium entry channels that are not store-operated but are likely regulated by PIP2 or diacylglycerol. Further, and consistent with the presently available data, selective homomeric or heteromeric interactions between TRPC monomers generate distinct agonist-stimulated cation permeable channels. We suggest that interaction between TRPC monomers, as well as the association of these channels with accessory proteins, determines their mode of regulation as well as their cellular localization and function. Currently identified accessory proteins include key Ca2+ signaling proteins as well as proteins involved in vesicle trafficking, cytoskeletal interactions, and scaffolding. Studies reported until now demonstrate that TRPC proteins are segregated into specific Ca2+ signaling complexes which can generate spatially and temporally controlled [Ca2+]i signals. Thus, the functional organization of TRPC channelosomes dictates not only their regulation by extracellular stimuli but also serves as a platform to coordinate specific downstream cellular functions that are regulated as a consequence of Ca2+ entry. This review will focus on the accessory proteins of TRPC channels and discuss the functional implications of TRPC channelosomes and their assembly in microdomains.
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Affiliation(s)
- Indu S Ambudkar
- Secretory Physiology Section, Gene Therapy and Therapeutics Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD 20892, USA.
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Ong HL, Liu X, Tsaneva-Atanasova K, Singh BB, Bandyopadhyay BC, Swaim WD, Russell JT, Hegde RS, Sherman A, Ambudkar IS. Relocalization of STIM1 for activation of store-operated Ca(2+) entry is determined by the depletion of subplasma membrane endoplasmic reticulum Ca(2+) store. J Biol Chem 2007; 282:12176-85. [PMID: 17298947 PMCID: PMC3309416 DOI: 10.1074/jbc.m609435200] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
STIM1 (stromal interacting molecule 1), an endoplasmic reticulum (ER) protein that controls store-operated Ca(2+) entry (SOCE), redistributes into punctae at the cell periphery after store depletion. This redistribution is suggested to have a causal role in activation of SOCE. However, whether peripheral STIM1 punctae that are involved in regulation of SOCE are determined by depletion of peripheral or more internal ER has not yet been demonstrated. Here we show that Ca(2+) depletion in subplasma membrane ER is sufficient for peripheral redistribution of STIM1 and activation of SOCE. 1 microM thapsigargin (Tg) induced substantial depletion of intracellular Ca(2+) stores and rapidly activated SOCE. In comparison, 1 nM Tg induced slower, about 60-70% less Ca(2+) depletion but similar SOCE. SOCE was confirmed by measuring I(SOC) in addition to Ca(2+), Mn(2+), and Ba(2+) entry. Importantly, 1 nM Tg caused redistribution of STIM1 only in the ER-plasma membrane junction, whereas 1 microM Tg caused a relatively global relocalization of STIM1 in the cell. During the time taken for STIM1 relocalization and SOCE activation, 1 nM Bodipy-fluorescein Tg primarily labeled the subplasma membrane region, whereas 1 microM Tg labeled the entire cell. The localization of Tg in the subplasma membrane region was associated with depletion of ER in this region and activation of SOCE. Together, these data suggest that peripheral STIM1 relocalization that is causal in regulation of SOCE is determined by the status of [Ca(2+)] in the ER in close proximity to the plasma membrane. Thus, the mechanism involved in regulation of SOCE is contained within the ER-plasma membrane junctional region.
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Affiliation(s)
- Hwei Ling Ong
- Secretory Physiology Section, Gene Therapy and Therapeutics Branch, NIDCR, National Institutes of Health, Bethesda, Maryland 20892
| | - Xibao Liu
- Secretory Physiology Section, Gene Therapy and Therapeutics Branch, NIDCR, National Institutes of Health, Bethesda, Maryland 20892
| | | | - Brij B. Singh
- Department of Biochemistry and Molecular Biology, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, North Dakota 58203
| | - Bidhan C. Bandyopadhyay
- Secretory Physiology Section, Gene Therapy and Therapeutics Branch, NIDCR, National Institutes of Health, Bethesda, Maryland 20892
| | - William D. Swaim
- Secretory Physiology Section, Gene Therapy and Therapeutics Branch, NIDCR, National Institutes of Health, Bethesda, Maryland 20892
| | - James T. Russell
- Microscopy and Imaging Core, NICHD, National Institutes of Health, Bethesda, Maryland 20892
| | - Ramanujan S. Hegde
- Cell Biology and Metabolism Branch, NICHD, National Institutes of Health, Bethesda, Maryland 20892
| | - Arthur Sherman
- Laboratory of Biological Modeling, NIDDK, National Institutes of Health, Bethesda, Maryland 20892
| | - Indu S. Ambudkar
- Secretory Physiology Section, Gene Therapy and Therapeutics Branch, NIDCR, National Institutes of Health, Bethesda, Maryland 20892
- To whom correspondence should be addressed: Bldg. 10, Rm. 1N-113, 10 Center Dr., National Institutes of Health, Bethesda, MD 20892. Tel.: 301-496-5298; Fax: 301-402-1228;
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Ong HL, Cheng KT, Liu X, Bandyopadhyay BC, Paria BC, Soboloff J, Pani B, Gwack Y, Srikanth S, Singh BB, Gill D, Ambudkar IS. Dynamic assembly of TRPC1-STIM1-Orai1 ternary complex is involved in store-operated calcium influx. Evidence for similarities in store-operated and calcium release-activated calcium channel components. J Biol Chem 2007; 282:9105-16. [PMID: 17224452 PMCID: PMC3309402 DOI: 10.1074/jbc.m608942200] [Citation(s) in RCA: 311] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Store-operated calcium entry (SOCE) is a ubiquitous mechanism that is mediated by distinct SOC channels, ranging from the highly selective calcium release-activated Ca2+ (CRAC) channel in rat basophilic leukemia and other hematopoietic cells to relatively Ca2+-selective or non-selective SOC channels in other cells. Although the exact composition of these channels is not yet established, TRPC1 contributes to SOC channels and regulation of physiological function of a variety of cell types. Recently, Orai1 and STIM1 have been suggested to be sufficient for generating CRAC channels. Here we show that Orai1 and STIM1 are also required for TRPC1-SOC channels. Knockdown of TRPC1, Orai1, or STIM1 attenuated, whereas overexpression of TRPC1, but not Orai1 or STIM1, induced an increase in SOC entry and I(SOC) in human salivary gland cells. All three proteins were co-localized in the plasma membrane region of cells, and thapsigargin increased co-immunoprecipitation of TRPC1 with STIM1, and Orai1 in human salivary gland cells as well as dispersed mouse submandibular gland cells. In aggregate, the data presented here reveal that all three proteins are essential for generation of I(SOC) in these cells and that dynamic assembly of TRPC1-STIM1-Orai1 ternary complex is involved in activation of SOC channel in response to internal Ca2+ store depletion. Thus, these data suggest a common molecular basis for SOC and CRAC channels.
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Affiliation(s)
- Hwei Ling Ong
- Secretory Physiology Section, Gene Therapy and Therapeutics Branch, NIDCR, National Institutes of Health, Bethesda, Maryland 20892
| | - Kwong Tai Cheng
- Secretory Physiology Section, Gene Therapy and Therapeutics Branch, NIDCR, National Institutes of Health, Bethesda, Maryland 20892
| | - Xibao Liu
- Secretory Physiology Section, Gene Therapy and Therapeutics Branch, NIDCR, National Institutes of Health, Bethesda, Maryland 20892
| | - Bidhan C. Bandyopadhyay
- Department of Biochemistry and Molecular Biology, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, North Dakota 58203
| | - Biman C. Paria
- Secretory Physiology Section, Gene Therapy and Therapeutics Branch, NIDCR, National Institutes of Health, Bethesda, Maryland 20892
| | - Jonathan Soboloff
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, Maryland 21201
| | - Biswaranjan Pani
- Department of Biochemistry and Molecular Biology, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, North Dakota 58203
| | - Yousang Gwack
- Department of Pathology, Harvard Medical School and the CBR Institute of Biomedical Research, Boston, Massachusetts 02115
| | - Sonal Srikanth
- Department of Pathology, Harvard Medical School and the CBR Institute of Biomedical Research, Boston, Massachusetts 02115
| | - Brij B. Singh
- Department of Biochemistry and Molecular Biology, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, North Dakota 58203
| | - Donald Gill
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, Maryland 21201
| | - Indu S. Ambudkar
- Secretory Physiology Section, Gene Therapy and Therapeutics Branch, NIDCR, National Institutes of Health, Bethesda, Maryland 20892
- To whom correspondence should be addressed: Secretory Physiology Section, Gene Therapy and Therapeutics Branch, NIDCR, NIH, Bldg. 10, Rm. 1N-113,10 Center Drive, Bethesda,MD20892. Tel.: 301-496-5298; Fax: 301-402-1228;
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Ong HL, Chen J, Chataway T, Brereton H, Zhang L, Downs T, Tsiokas L, Barritt G. Specific detection of the endogenous transient receptor potential (TRP)-1 protein in liver and airway smooth muscle cells using immunoprecipitation and Western-blot analysis. Biochem J 2002; 364:641-8. [PMID: 12049627 PMCID: PMC1222612 DOI: 10.1042/bj20020061] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Although there are numerous reports of the presence of mRNA encoding the transient receptor potential (TRP)-1 protein in animal cells and of the detection of the heterologously expressed TRP-1 protein by Western-blot analysis, it has proved difficult to unequivocally detect endogenous TRP-1 proteins. A combination of immunoprecipitation and Western-blot techniques, employing a polyclonal antibody and a monoclonal antibody respectively, was developed. Using this technique, a band of approx. 80 kDa was detected in extracts of H4-IIE rat liver hepatoma cell line and guinea-pig airway smooth muscle (ASM) cells transfected with human TRPC-1 cDNA. In extracts of untransfected H4-IIE cells, ASM cells, rat brain and guinea-pig brain, a band of approx. 92 kDa was detected. Reverse transcriptase PCR experiments detected cDNA encoding both the alpha- and beta-isoforms of TRP-1 in H4-IIE cells. Treatment of protein extracts with peptide N-glycosidase F indicated that the 92 kDa band represents an N-glycosylated protein. Western blots conducted with a commercial polyclonal anti-(TRP-1) antibody (Alm) detected a band of 120 kDa in extracts of H4-IIE cells and guinea-pig ASM cells. A combination of immunoprecipitation and Western-blotting techniques with the Alm antibody did not detect any bands at 92 kDa or 120 kDa in extracts of H4-IIE and ASM cells. It is concluded that (a) the 92-kDa band detected in untransfected H4-IIE and ASM cells corresponds to the N-glycosylated beta-isoform of endogenous TRP-1, (b) the combined immunoprecipitation and Western-blot approach, employing two different antibodies, provides a reliable and specific procedure for detecting endogenous TRP-1 proteins, and (c) that caution is required in developing and utilizing anti-(TRP-1) antibodies.
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Affiliation(s)
- Hwei Ling Ong
- Department of Medical Biochemistry, School of Medicine, Faculty of Health Sciences, Flinders University, GPO Box 2100, Adelaide, South Australia 5001, Australia
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Sanda PN, Dove DB, Ong HL, Jansen SA, Hoffmann R. Role of surface bonding on liquid-crystal alignment at metal surfaces. Phys Rev A Gen Phys 1989; 39:2653-2658. [PMID: 9901537 DOI: 10.1103/physreva.39.2653] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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Ong HL. Wave propagation in cholesteric and chiral smectic-C liquid crystals: Exact and generalized geometrical-optics-approximation solutions. Phys Rev A Gen Phys 1988; 37:3520-3529. [PMID: 9900099 DOI: 10.1103/physreva.37.3520] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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42
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Karn AJ, Arakelian SM, Shen YR, Ong HL. Observation of magnetic-field-induced first-order optical Fréedericksz transition in a nematic film. Phys Rev Lett 1986; 57:448-451. [PMID: 10034062 DOI: 10.1103/physrevlett.57.448] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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43
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Ong HL. Optical-field-enhanced and static-field-induced first-order Fréedericksz transitions in a planar parallel nematic liquid crystal. Phys Rev A Gen Phys 1986; 33:3550-3553. [PMID: 9897080 DOI: 10.1103/physreva.33.3550] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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44
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Ong HL. Electromagnetic fields in layered-inhomogeneous uniaxial media: Validation criterion and higher-order solutions of the geometrical-optics approximation. Phys Rev A Gen Phys 1985; 32:1098-1105. [PMID: 9896166 DOI: 10.1103/physreva.32.1098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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45
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Ong HL. Magnetic-field-enhanced and -suppressed intrinsic optical bistability in nematic liquid crystals. Phys Rev A Gen Phys 1985; 31:3450-3453. [PMID: 9895901 DOI: 10.1103/physreva.31.3450] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/11/2023]
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