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Bacsa B, Hopl V, Derler I. Synthetic Biology Meets Ca 2+ Release-Activated Ca 2+ Channel-Dependent Immunomodulation. Cells 2024; 13:468. [PMID: 38534312 DOI: 10.3390/cells13060468] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2024] [Revised: 02/27/2024] [Accepted: 03/05/2024] [Indexed: 03/28/2024] Open
Abstract
Many essential biological processes are triggered by the proximity of molecules. Meanwhile, diverse approaches in synthetic biology, such as new biological parts or engineered cells, have opened up avenues to precisely control the proximity of molecules and eventually downstream signaling processes. This also applies to a main Ca2+ entry pathway into the cell, the so-called Ca2+ release-activated Ca2+ (CRAC) channel. CRAC channels are among other channels are essential in the immune response and are activated by receptor-ligand binding at the cell membrane. The latter initiates a signaling cascade within the cell, which finally triggers the coupling of the two key molecular components of the CRAC channel, namely the stromal interaction molecule, STIM, in the ER membrane and the plasma membrane Ca2+ ion channel, Orai. Ca2+ entry, established via STIM/Orai coupling, is essential for various immune cell functions, including cytokine release, proliferation, and cytotoxicity. In this review, we summarize the tools of synthetic biology that have been used so far to achieve precise control over the CRAC channel pathway and thus over downstream signaling events related to the immune response.
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Affiliation(s)
- Bernadett Bacsa
- Division of Medical Physics und Biophysics, Medical University of Graz, A-8010 Graz, Austria
| | - Valentina Hopl
- Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, A-4020 Linz, Austria
| | - Isabella Derler
- Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, A-4020 Linz, Austria
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2
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Kodakandla G, Akimzhanov AM, Boehning D. Regulatory mechanisms controlling store-operated calcium entry. Front Physiol 2023; 14:1330259. [PMID: 38169682 PMCID: PMC10758431 DOI: 10.3389/fphys.2023.1330259] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Accepted: 12/08/2023] [Indexed: 01/05/2024] Open
Abstract
Calcium influx through plasma membrane ion channels is crucial for many events in cellular physiology. Cell surface stimuli lead to the production of inositol 1,4,5-trisphosphate (IP3), which binds to IP3 receptors (IP3R) in the endoplasmic reticulum (ER) to release calcium pools from the ER lumen. This leads to the depletion of ER calcium pools, which has been termed store depletion. Store depletion leads to the dissociation of calcium ions from the EF-hand motif of the ER calcium sensor Stromal Interaction Molecule 1 (STIM1). This leads to a conformational change in STIM1, which helps it to interact with the plasma membrane (PM) at ER:PM junctions. At these ER:PM junctions, STIM1 binds to and activates a calcium channel known as Orai1 to form calcium release-activated calcium (CRAC) channels. Activation of Orai1 leads to calcium influx, known as store-operated calcium entry (SOCE). In addition to Orai1 and STIM1, the homologs of Orai1 and STIM1, such as Orai2/3 and STIM2, also play a crucial role in calcium homeostasis. The influx of calcium through the Orai channel activates a calcium current that has been termed the CRAC current. CRAC channels form multimers and cluster together in large macromolecular assemblies termed "puncta". How CRAC channels form puncta has been contentious since their discovery. In this review, we will outline the history of SOCE, the molecular players involved in this process, as well as the models that have been proposed to explain this critical mechanism in cellular physiology.
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Affiliation(s)
- Goutham Kodakandla
- Department of Biomedical Sciences, Cooper Medical School of Rowan University, Camden, NJ, United States
| | - Askar M. Akimzhanov
- Department of Biochemistry and Molecular Biology, McGovern Medical School, Houston, TX, United States
| | - Darren Boehning
- Department of Biomedical Sciences, Cooper Medical School of Rowan University, Camden, NJ, United States
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3
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Kodakandla G, Akimzhanov AM, Boehning D. Regulatory mechanisms controlling store-operated calcium entry. ARXIV 2023:arXiv:2309.06907v3. [PMID: 37744466 PMCID: PMC10516112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Indexed: 09/26/2023]
Abstract
Calcium influx through plasma membrane ion channels is crucial for many events in cellular physiology. Cell surface stimuli lead to the production of inositol 1,4,5-trisphosphate (IP3), which binds to IP3 receptors (IP3R) in the endoplasmic reticulum (ER) to release calcium pools from the ER lumen. This leads to the depletion of ER calcium pools, which has been termed store depletion. Store depletion leads to the dissociation of calcium ions from the EF-hand motif of the ER calcium sensor Stromal Interaction Molecule 1 (STIM1). This leads to a conformational change in STIM1, which helps it to interact with the plasma membrane (PM) at ER:PM junctions. At these ER:PM junctions, STIM1 binds to and activates a calcium channel known as Orai1 to form calcium-release activated calcium (CRAC) channels. Activation of Orai1 leads to calcium influx, known as store-operated calcium entry (SOCE). In addition to Orai1 and STIM1, the homologs of Orai1 and STIM1, such as Orai2/3 and STIM2, also play a crucial role in calcium homeostasis. The influx of calcium through the Orai channel activates a calcium current that has been termed the CRAC current. CRAC channels form multimers and cluster together in large macromolecular assemblies termed "puncta". How CRAC channels form puncta has been contentious since their discovery. In this review, we will outline the history of SOCE, the molecular players involved in this process, as well as the models that have been proposed to explain this critical mechanism in cellular physiology.
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Affiliation(s)
- Goutham Kodakandla
- Department of Biomedical Sciences, Cooper Medical School of Rowan University, Camden, NJ, USA, 08103
| | - Askar M. Akimzhanov
- Department of Biochemistry and Molecular Biology, McGovern Medical School, Houston, Texas, USA, 77030
| | - Darren Boehning
- Department of Biomedical Sciences, Cooper Medical School of Rowan University, Camden, NJ, USA, 08103
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4
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Gross S, Womer L, Kappes DJ, Soboloff J. Multifaceted control of T cell differentiation by STIM1. Trends Biochem Sci 2023; 48:1083-1097. [PMID: 37696713 PMCID: PMC10787584 DOI: 10.1016/j.tibs.2023.08.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Revised: 08/08/2023] [Accepted: 08/18/2023] [Indexed: 09/13/2023]
Abstract
In T cells, stromal interaction molecule (STIM) and Orai are dispensable for conventional T cell development, but critical for activation and differentiation. This review focuses on novel STIM-dependent mechanisms for control of Ca2+ signals during T cell activation and its impact on mitochondrial function and transcriptional activation for control of T cell differentiation and function. We highlight areas that require further work including the roles of plasma membrane Ca2+ ATPase (PMCA) and partner of STIM1 (POST) in controlling Orai function. A major knowledge gap also exists regarding the independence of T cell development from STIM and Orai, despite compelling evidence that it requires Ca2+ signals. Resolving these and other outstanding questions ensures that the field will remain active for many years to come.
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Affiliation(s)
- Scott Gross
- Fels Cancer Institute for Personalized Medicine, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, 19140, USA
| | - Lauren Womer
- Fels Cancer Institute for Personalized Medicine, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, 19140, USA
| | | | - Jonathan Soboloff
- Fels Cancer Institute for Personalized Medicine, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, 19140, USA; Department of Cancer and Cellular Biology, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, 19140, USA.
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5
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Tiffner A, Hopl V, Derler I. CRAC and SK Channels: Their Molecular Mechanisms Associated with Cancer Cell Development. Cancers (Basel) 2022; 15:cancers15010101. [PMID: 36612099 PMCID: PMC9817886 DOI: 10.3390/cancers15010101] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Revised: 12/16/2022] [Accepted: 12/19/2022] [Indexed: 12/28/2022] Open
Abstract
Cancer represents a major health burden worldwide. Several molecular targets have been discovered alongside treatments with positive clinical outcomes. However, the reoccurrence of cancer due to therapy resistance remains the primary cause of mortality. Endeavors in pinpointing new markers as molecular targets in cancer therapy are highly desired. The significance of the co-regulation of Ca2+-permeating and Ca2+-regulated ion channels in cancer cell development, proliferation, and migration make them promising molecular targets in cancer therapy. In particular, the co-regulation of the Orai1 and SK3 channels has been well-studied in breast and colon cancer cells, where it finally leads to an invasion-metastasis cascade. Nevertheless, many questions remain unanswered, such as which key molecular components determine and regulate their interplay. To provide a solid foundation for a better understanding of this ion channel co-regulation in cancer, we first shed light on the physiological role of Ca2+ and how this ion is linked to carcinogenesis. Then, we highlight the structure/function relationship of Orai1 and SK3, both individually and in concert, their role in the development of different types of cancer, and aspects that are not yet known in this context.
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6
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West SJ, Boehning D, Akimzhanov AM. Regulation of T cell function by protein S-acylation. Front Physiol 2022; 13:1040968. [PMID: 36467682 PMCID: PMC9709458 DOI: 10.3389/fphys.2022.1040968] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Accepted: 11/02/2022] [Indexed: 10/26/2023] Open
Abstract
S-acylation, the reversible lipidation of free cysteine residues with long-chain fatty acids, is a highly dynamic post-translational protein modification that has recently emerged as an important regulator of the T cell function. The reversible nature of S-acylation sets this modification apart from other forms of protein lipidation and allows it to play a unique role in intracellular signal transduction. In recent years, a significant number of T cell proteins, including receptors, enzymes, ion channels, and adaptor proteins, were identified as S-acylated. It has been shown that S-acylation critically contributes to their function by regulating protein localization, stability and protein-protein interactions. Furthermore, it has been demonstrated that zDHHC protein acyltransferases, the family of enzymes mediating this modification, also play a prominent role in T cell activation and differentiation. In this review, we aim to highlight the diversity of proteins undergoing S-acylation in T cells, elucidate the mechanisms by which reversible lipidation can impact protein function, and introduce protein acyltransferases as a novel class of regulatory T cell proteins.
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Affiliation(s)
- Savannah J. West
- Department of Biochemistry and Molecular Biology, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX, United States
- MD Anderson Cancer Center and University of Texas Health Science at Houston Graduate School, Houston, TX, United States
| | - Darren Boehning
- Department of Biomedical Sciences, Cooper Medical School of Rowan University, Camden, NJ, United States
| | - Askar M. Akimzhanov
- Department of Biochemistry and Molecular Biology, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX, United States
- MD Anderson Cancer Center and University of Texas Health Science at Houston Graduate School, Houston, TX, United States
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7
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Kodakandla G, West SJ, Wang Q, Tewari R, Zhu MX, Akimzhanov AM, Boehning D. Dynamic S-acylation of the ER-resident protein stromal interaction molecule 1 (STIM1) is required for store-operated Ca2+ entry. J Biol Chem 2022; 298:102303. [PMID: 35934052 PMCID: PMC9463532 DOI: 10.1016/j.jbc.2022.102303] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Revised: 07/15/2022] [Accepted: 07/18/2022] [Indexed: 02/07/2023] Open
Abstract
Many cell surface stimuli cause calcium release from endoplasmic reticulum (ER) stores to regulate cellular physiology. Upon ER calcium store depletion, the ER-resident protein stromal interaction molecule 1 (STIM1) physically interacts with plasma membrane protein Orai1 to induce calcium release–activated calcium (CRAC) currents that conduct calcium influx from the extracellular milieu. Although the physiological relevance of this process is well established, the mechanism supporting the assembly of these proteins is incompletely understood. Earlier we demonstrated a previously unknown post-translational modification of Orai1 with long-chain fatty acids, known as S-acylation. We found that S-acylation of Orai1 is dynamically regulated in a stimulus-dependent manner and essential for its function as a calcium channel. Here using the acyl resin–assisted capture assay, we show that STIM1 is also rapidly S-acylated at cysteine 437 upon ER calcium store depletion. Using a combination of live cell imaging and electrophysiology approaches with a mutant STIM1 protein, which could not be S-acylated, we determined that the S-acylation of STIM1 is required for the assembly of STIM1 into puncta with Orai1 and full CRAC channel function. Together with the S-acylation of Orai1, our data suggest that stimulus-dependent S-acylation of CRAC channel components Orai1 and STIM1 is a critical mechanism facilitating the CRAC channel assembly and function.
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Affiliation(s)
- Goutham Kodakandla
- Department of Biomedical Sciences, Cooper Medical School of Rowan University, Camden, New Jersey, USA
| | - Savannah J West
- Department of Biochemistry and Molecular Biology, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, Texas, USA
| | - Qiaochu Wang
- Department of Integrative Biology and Pharmacology, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, Texas, USA
| | - Ritika Tewari
- Department of Biochemistry and Molecular Biology, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, Texas, USA
| | - Michael X Zhu
- Department of Integrative Biology and Pharmacology, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, Texas, USA
| | - Askar M Akimzhanov
- Department of Biochemistry and Molecular Biology, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, Texas, USA.
| | - Darren Boehning
- Department of Biomedical Sciences, Cooper Medical School of Rowan University, Camden, New Jersey, USA.
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Hegde M, Daimary UD, Jose S, Sajeev A, Chinnathambi A, Alharbi SA, Shakibaei M, Kunnumakkara AB. Differential Expression of Genes Regulating Store-operated Calcium Entry in Conjunction With Mitochondrial Dynamics as Potential Biomarkers for Cancer: A Single-Cell RNA Analysis. Front Genet 2022; 13:866473. [PMID: 35711942 PMCID: PMC9197647 DOI: 10.3389/fgene.2022.866473] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Accepted: 04/27/2022] [Indexed: 11/13/2022] Open
Abstract
Regulation of intracellular concentration of calcium levels is crucial for cell signaling, homeostasis, and in the pathology of diseases including cancer. Agonist-induced entry of calcium ions into the non-excitable cells is mediated by store-operated calcium channels (SOCs). This pathway is activated by the release of calcium ions from the endoplasmic reticulum and further regulated by the calcium uptake through mitochondria leading to calcium-dependent inactivation of calcium-release activated calcium channels (CARC). SOCs including stromal interaction molecules (STIM) and ORAI proteins have been implicated in tumor growth, progression, and metastasis. In the present study, we analyzed the mRNA and protein expression of genes mediating SOCs-STIM1, STIM2, ORAI1, ORAI2, ORAI3, TRPC1, TRPC3, TRPC4, TRPC5, TRPC6, TRPC7, TRPV1, TRPV2, TRPM1, and TRPM7 in head and neck squamous cell cancer (HNSC) patients using TCGA and CPTAC analysis. Further, our in silico analysis showed a significant correlation between the expression of SOCs and genes involved in the mitochondrial dynamics (MDGs) both at mRNA and protein levels. Protein-protein docking results showed lower binding energy for SOCs with MDGs. Subsequently, we validated these results using gene expression and single-cell RNA sequencing datasets retrieved from Gene Expression Omnibus (GEO). Single-cell gene expression analysis of HNSC tumor tissues revealed that SOCs expression is remarkably associated with the MDGs expression in both cancer and fibroblast cells.
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Affiliation(s)
- Mangala Hegde
- Cancer Biology Laboratory, Department of Biosciences and Bioengineering, Indian Institute of Technology-Guwahati, Guwahati, India.,DBT-AIST International Center for Translational and Environmental Research, Indian Institute of Technology-Guwahati, Guwahati, India
| | - Uzini Devi Daimary
- Cancer Biology Laboratory, Department of Biosciences and Bioengineering, Indian Institute of Technology-Guwahati, Guwahati, India.,DBT-AIST International Center for Translational and Environmental Research, Indian Institute of Technology-Guwahati, Guwahati, India
| | - Sandra Jose
- Cancer Biology Laboratory, Department of Biosciences and Bioengineering, Indian Institute of Technology-Guwahati, Guwahati, India.,DBT-AIST International Center for Translational and Environmental Research, Indian Institute of Technology-Guwahati, Guwahati, India
| | - Anjana Sajeev
- Cancer Biology Laboratory, Department of Biosciences and Bioengineering, Indian Institute of Technology-Guwahati, Guwahati, India.,DBT-AIST International Center for Translational and Environmental Research, Indian Institute of Technology-Guwahati, Guwahati, India
| | - Arunachalam Chinnathambi
- Department of Botany and Microbiology, College of Science, King Saud University, Riyadh, Saudi Arabia
| | - Sulaiman Ali Alharbi
- Department of Botany and Microbiology, College of Science, King Saud University, Riyadh, Saudi Arabia
| | - Mehdi Shakibaei
- Musculoskeletal Research Group and Tumor Biology, Faculty of Medicine, Institute of Anatomy, Ludwig-Maximilian-University Munich, Munich, Germany
| | - Ajaikumar B Kunnumakkara
- Cancer Biology Laboratory, Department of Biosciences and Bioengineering, Indian Institute of Technology-Guwahati, Guwahati, India.,DBT-AIST International Center for Translational and Environmental Research, Indian Institute of Technology-Guwahati, Guwahati, India
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9
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Humer C, Romanin C, Höglinger C. Highlighting the Multifaceted Role of Orai1 N-Terminal- and Loop Regions for Proper CRAC Channel Functions. Cells 2022; 11:371. [PMID: 35159181 PMCID: PMC8834118 DOI: 10.3390/cells11030371] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Revised: 01/14/2022] [Accepted: 01/15/2022] [Indexed: 11/16/2022] Open
Abstract
Orai1, the Ca2+-selective pore in the plasma membrane, is one of the key components of the Ca2+release-activated Ca2+ (CRAC) channel complex. Activated by the Ca2+ sensor in the endoplasmic reticulum (ER) membrane, stromal interaction molecule 1 (STIM1), via direct interaction when ER luminal Ca2+ levels recede, Orai1 helps to maintain Ca2+ homeostasis within a cell. It has already been proven that the C-terminus of Orai1 is indispensable for channel activation. However, there is strong evidence that for CRAC channels to function properly and maintain all typical hallmarks, such as selectivity and reversal potential, additional parts of Orai1 are needed. In this review, we focus on these sites apart from the C-terminus; namely, the second loop and N-terminus of Orai1 and on their multifaceted role in the functioning of CRAC channels.
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Affiliation(s)
| | | | - Carmen Höglinger
- Institute of Biophysics, Johannes Kepler University Linz, Gruberstrasse 40, 4020 Linz, Austria; (C.H.); (C.R.)
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10
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Wang YY, Wang WC, Su CW, Hsu CW, Yuan SS, Chen YK. Expression of Orai1 and STIM1 in human oral squamous cell carcinogenesis. J Dent Sci 2022; 17:78-88. [PMID: 35028023 PMCID: PMC8739746 DOI: 10.1016/j.jds.2021.07.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Revised: 07/07/2021] [Indexed: 12/21/2022] Open
Abstract
Background/purpose Return of Ca2+ to endoplasmic reticulum is mediated by Orai/STIM-mediated store-operated Ca2+ entry (SOCE) channel. We aimed to investigate Orai1 and STIM1 expressions in human oral carcinogenesis. Materials and methods Sixty-six oral squamous cell carcinomas (OSCCs), 14 oral potentially malignant disorders (OPMD) with moderate-severe oral epithelial dysplasia (OED), 19 OPMD with mild OED, and 14 normal oral mucosa (NOM) samples were subjected to immunohistochemical staining. Two human oral cancer cell lines (OCCLs), an oral premalignant cell line (DOK), and a normal oral keratinocyte culture (HOK) were used for Western blot and real-time quantitative reverse transcription-polymerase chain reaction. OCCLs were evaluated for proliferation, migration, and invasion assays. Results Orai1 and STIM1 protein and mRNA expressions in OSCC were significantly enhanced as compared with normal samples. Protein expressions of Orai1 and STIM1 in OCCLs were significantly enhanced as compared with HOK. Significant decreases in degrees of proliferation, migration and invasion were noted in OCCLs with Orai1 and STIM1 siRNA transfection as compared with those without transfection. Significantly increased Orai1 and STIM1 protein levels were noted in OPMD with moderate-severe OED as compared with those with mild OED. Conclusion Our results indicate that Orai1 and STIM1 overexpression is associated with human oral carcinogenesis.
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Affiliation(s)
- Yen-Yun Wang
- School of Dentistry, College of Dental Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.,Department of Medical Research, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Wen-Chen Wang
- School of Dentistry, College of Dental Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.,Division of Oral Pathology & Maxillofacial Radiology, Department of Dentistry, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan.,Oral & Maxillofacial Imaging Center, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Chiang-Wei Su
- Division of Oral & Maxillofacial Surgery, Department of Dentistry, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan
| | - Ching-Wei Hsu
- Division of Oral & Maxillofacial Surgery, Department of Dentistry, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan
| | - Shyng-Shiou Yuan
- Department of Medical Research, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan.,Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.,Translational Research Center, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan.,Department of Obstetrics and Gynecology and Department of Medical Research, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Yuk-Kwan Chen
- School of Dentistry, College of Dental Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.,Division of Oral Pathology & Maxillofacial Radiology, Department of Dentistry, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan.,Oral & Maxillofacial Imaging Center, Kaohsiung Medical University, Kaohsiung, Taiwan
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11
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Fresquez AM, White C. Extracellular cysteines C226 and C232 mediate hydrogen sulfide-dependent inhibition of Orai3-mediated store-operated calcium entry. Am J Physiol Cell Physiol 2022; 322:C38-C48. [PMID: 34788146 PMCID: PMC8759961 DOI: 10.1152/ajpcell.00490.2019] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The gaseous signaling molecule hydrogen sulfide (H2S) physiologically regulates store-operated Ca2+ entry (SOCE). The SOCE machinery consists of the plasma membrane-localized Orai channels (Orai1-3) and endoplasmic reticulum-localized stromal interaction molecule (STIM)1 and STIM2 proteins. H2S inhibits Orai3- but not Orai1- or Orai2-mediated SOCE. The current objective was to define the mechanism by which H2S selectively modifies Orai3. We measured SOCE and STIM1/Orai3 dynamics and interactions in HEK293 cells exogenously expressing fluorescently tagged human STIM1 and Orai3 in the presence and absence of the H2S donor GYY4137. Two cysteines (C226 and C232) are present in Orai3 that are absent in the Orai1 and Orai2. When we mutated either of these cysteines to serine, alone or in combination, SOCE inhibition by H2S was abolished. We also established that inhibition was dependent on an interaction with STIM1. To further define the effects of H2S on STIM1/Orai3 interaction, we performed a series of fluorescence recovery after photobleaching (FRAP), colocalization, and fluorescence resonance energy transfer (FRET) experiments. Treatment with H2S did not affect the mobility of Orai3 in the membrane, nor did it influence STIM1/Orai3 puncta formation or STIM1-Orai3 protein-protein interactions. These data support a model in which H2S modification of Orai3 at cysteines 226 and 232 limits SOCE evoked upon store depletion and STIM1 engagement, by a mechanism independent of the interaction between Orai3 and STIM1.
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Affiliation(s)
- Adriana M. Fresquez
- 1Discipline of Physiology and Biophysics, Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, Illinois,2Center for Cancer Cell Biology, Immunology, and Infection, Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, Illinois
| | - Carl White
- 1Discipline of Physiology and Biophysics, Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, Illinois,2Center for Cancer Cell Biology, Immunology, and Infection, Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, Illinois
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12
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Tiffner A, Hopl V, Schober R, Sallinger M, Grabmayr H, Höglinger C, Fahrner M, Lunz V, Maltan L, Frischauf I, Krivic D, Bhardwaj R, Schindl R, Hediger MA, Derler I. Orai1 Boosts SK3 Channel Activation. Cancers (Basel) 2021; 13:6357. [PMID: 34944977 PMCID: PMC8699475 DOI: 10.3390/cancers13246357] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Accepted: 12/13/2021] [Indexed: 12/20/2022] Open
Abstract
The interplay of SK3, a Ca2+ sensitive K+ ion channel, with Orai1, a Ca2+ ion channel, has been reported to increase cytosolic Ca2+ levels, thereby triggering proliferation of breast and colon cancer cells, although a molecular mechanism has remained elusive to date. We show in the current study, via heterologous protein expression, that Orai1 can enhance SK3 K+ currents, in addition to constitutively bound calmodulin (CaM). At low cytosolic Ca2+ levels that decrease SK3 K+ permeation, co-expressed Orai1 potentiates SK3 currents. This positive feedback mechanism of SK3 and Orai1 is enabled by their close co-localization. Remarkably, we discovered that loss of SK3 channel activity due to overexpressed CaM mutants could be restored by Orai1, likely via its interplay with the SK3-CaM binding site. Mapping for interaction sites within Orai1, we identified that the cytosolic strands and pore residues are critical for a functional communication with SK3. Moreover, STIM1 has a bimodal role in SK3-Orai1 regulation. Under physiological ionic conditions, STIM1 is able to impede SK3-Orai1 interplay by significantly decreasing their co-localization. Forced STIM1-Orai1 activity and associated Ca2+ influx promote SK3 K+ currents. The dynamic regulation of Orai1 to boost endogenous SK3 channels was also determined in the human prostate cancer cell line LNCaP.
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Affiliation(s)
- Adéla Tiffner
- JKU Life Science Center, Institute of Biophysics, Johannes Kepler University Linz, A-4020 Linz, Austria; (A.T.); (V.H.); (R.S.); (M.S.); (H.G.); (C.H.); (M.F.); (V.L.); (L.M.); (I.F.)
| | - Valentina Hopl
- JKU Life Science Center, Institute of Biophysics, Johannes Kepler University Linz, A-4020 Linz, Austria; (A.T.); (V.H.); (R.S.); (M.S.); (H.G.); (C.H.); (M.F.); (V.L.); (L.M.); (I.F.)
| | - Romana Schober
- JKU Life Science Center, Institute of Biophysics, Johannes Kepler University Linz, A-4020 Linz, Austria; (A.T.); (V.H.); (R.S.); (M.S.); (H.G.); (C.H.); (M.F.); (V.L.); (L.M.); (I.F.)
- Gottfried Schatz Research Centre, Medical University of Graz, A-8010 Graz, Austria; (D.K.); (R.S.)
| | - Matthias Sallinger
- JKU Life Science Center, Institute of Biophysics, Johannes Kepler University Linz, A-4020 Linz, Austria; (A.T.); (V.H.); (R.S.); (M.S.); (H.G.); (C.H.); (M.F.); (V.L.); (L.M.); (I.F.)
| | - Herwig Grabmayr
- JKU Life Science Center, Institute of Biophysics, Johannes Kepler University Linz, A-4020 Linz, Austria; (A.T.); (V.H.); (R.S.); (M.S.); (H.G.); (C.H.); (M.F.); (V.L.); (L.M.); (I.F.)
| | - Carmen Höglinger
- JKU Life Science Center, Institute of Biophysics, Johannes Kepler University Linz, A-4020 Linz, Austria; (A.T.); (V.H.); (R.S.); (M.S.); (H.G.); (C.H.); (M.F.); (V.L.); (L.M.); (I.F.)
| | - Marc Fahrner
- JKU Life Science Center, Institute of Biophysics, Johannes Kepler University Linz, A-4020 Linz, Austria; (A.T.); (V.H.); (R.S.); (M.S.); (H.G.); (C.H.); (M.F.); (V.L.); (L.M.); (I.F.)
| | - Victoria Lunz
- JKU Life Science Center, Institute of Biophysics, Johannes Kepler University Linz, A-4020 Linz, Austria; (A.T.); (V.H.); (R.S.); (M.S.); (H.G.); (C.H.); (M.F.); (V.L.); (L.M.); (I.F.)
| | - Lena Maltan
- JKU Life Science Center, Institute of Biophysics, Johannes Kepler University Linz, A-4020 Linz, Austria; (A.T.); (V.H.); (R.S.); (M.S.); (H.G.); (C.H.); (M.F.); (V.L.); (L.M.); (I.F.)
| | - Irene Frischauf
- JKU Life Science Center, Institute of Biophysics, Johannes Kepler University Linz, A-4020 Linz, Austria; (A.T.); (V.H.); (R.S.); (M.S.); (H.G.); (C.H.); (M.F.); (V.L.); (L.M.); (I.F.)
| | - Denis Krivic
- Gottfried Schatz Research Centre, Medical University of Graz, A-8010 Graz, Austria; (D.K.); (R.S.)
| | - Rajesh Bhardwaj
- Department of Nephrology and Hypertension, University of Bern, Inselspital, Freiburgstrasse 15, CH-3010 Bern, Switzerland; (R.B.); (M.A.H.)
- Department of Biomedical Research, University of Bern, Inselspital, Freiburgstrasse 15, CH-3010 Bern, Switzerland
| | - Rainer Schindl
- Gottfried Schatz Research Centre, Medical University of Graz, A-8010 Graz, Austria; (D.K.); (R.S.)
| | - Matthias A. Hediger
- Department of Nephrology and Hypertension, University of Bern, Inselspital, Freiburgstrasse 15, CH-3010 Bern, Switzerland; (R.B.); (M.A.H.)
- Department of Biomedical Research, University of Bern, Inselspital, Freiburgstrasse 15, CH-3010 Bern, Switzerland
| | - Isabella Derler
- JKU Life Science Center, Institute of Biophysics, Johannes Kepler University Linz, A-4020 Linz, Austria; (A.T.); (V.H.); (R.S.); (M.S.); (H.G.); (C.H.); (M.F.); (V.L.); (L.M.); (I.F.)
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13
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Carreras-Sureda A, Abrami L, Ji-Hee K, Wang WA, Henry C, Frieden M, Didier M, van der Goot FG, Demaurex N. S-acylation by ZDHHC20 targets ORAI1 channels to lipid rafts for efficient Ca 2+ signaling by Jurkat T cell receptors at the immune synapse. eLife 2021; 10:72051. [PMID: 34913437 PMCID: PMC8683079 DOI: 10.7554/elife.72051] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Accepted: 11/29/2021] [Indexed: 12/29/2022] Open
Abstract
Efficient immune responses require Ca2+ fluxes across ORAI1 channels during engagement of T cell receptors (TCR) at the immune synapse (IS) between T cells and antigen presenting cells. Here, we show that ZDHHC20-mediated S-acylation of the ORAI1 channel at residue Cys143 promotes TCR recruitment and signaling at the IS. Cys143 mutations reduced ORAI1 currents and store-operated Ca2+ entry in HEK-293 cells and nearly abrogated long-lasting Ca2+ elevations, NFATC1 translocation, and IL-2 secretion evoked by TCR engagement in Jurkat T cells. The acylation-deficient channel remained in cholesterol-poor domains upon enforced ZDHHC20 expression and was recruited less efficiently to the IS along with actin and TCR. Our results establish S-acylation as a critical regulator of ORAI1 channel trafficking and function at the IS and reveal that ORAI1 S-acylation enhances TCR recruitment to the synapse.
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Affiliation(s)
| | - Laurence Abrami
- Faculty of Life Sciences, Global Health Institute, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Kim Ji-Hee
- Department of Physiology, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea
| | - Wen-An Wang
- Department of Cell Physiology and Metabolism, Geneva, Switzerland
| | | | - Maud Frieden
- Department of Cell Physiology and Metabolism, Geneva, Switzerland
| | - Monica Didier
- Department of Cell Physiology and Metabolism, Geneva, Switzerland
| | - F Gisou van der Goot
- Faculty of Life Sciences, Global Health Institute, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Nicolas Demaurex
- Department of Cell Physiology and Metabolism, Geneva, Switzerland
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14
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Voros O, Panyi G, Hajdu P. Immune Synapse Residency of Orai1 Alters Ca 2+ Response of T Cells. Int J Mol Sci 2021; 22:ijms222111514. [PMID: 34768945 PMCID: PMC8583858 DOI: 10.3390/ijms222111514] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 10/11/2021] [Accepted: 10/18/2021] [Indexed: 12/19/2022] Open
Abstract
CRAC, which plays important role in Ca2+-dependent T-lymphocyte activation, is composed of the ER-resident STIM1 and the plasma membrane Orai1 pore-forming subunit. Both accumulate at the immunological synapse (IS) between a T cell and an antigen-presenting cell (APC). We hypothesized that adapter/interacting proteins regulate Orai1 residence in the IS. We could show that mGFP-tagged Orai1-Full channels expressed in Jurkat cells had a biphasic IS-accumulation kinetics peaked at 15 min. To understand the background of Orai1 IS-redistribution we knocked down STIM1 and SAP97 (adaptor protein with a short IS-residency (15 min) and ability to bind Orai1 N-terminus): the mGFP-Orai1-Full channels kept on accumulating in the IS up to the 60th minute in the STIM1- and SAP97-lacking Jurkat cells. Deletion of Orai1 N terminus (mGFP-Orai1-Δ72) resulted in the same time course as described for STIM1/SAP97 knock-down cells. Ca2+-imaging of IS-engaged T-cells revealed that of Orai1 residency modifies the Ca2+-response: cells expressing mGFP-Orai1-Δ72 construct or mGFP-Orai1-Full in SAP-97 knock-down cells showed higher number of Ca2+-oscillation up to the 90th minute after IS formation. Overall, these data suggest that SAP97 may contribute to the short-lived IS-residency of Orai1 and binding of STIM1 to Orai1 N-terminus is necessary for SAP97-Orai1 interaction.
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Affiliation(s)
- Orsolya Voros
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Egyetem tér 1, 4032 Debrecen, Hungary; (O.V.); (G.P.)
| | - György Panyi
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Egyetem tér 1, 4032 Debrecen, Hungary; (O.V.); (G.P.)
| | - Péter Hajdu
- Department of Biophysics and Cell Biology, Faculty of Dentistry, University of Debrecen, Nagyerdei krt. 98, 4032 Debrecen, Hungary
- Correspondence: ; Tel.: +36-52-258603
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15
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Höglinger C, Grabmayr H, Maltan L, Horvath F, Krobath H, Muik M, Tiffner A, Renger T, Romanin C, Fahrner M, Derler I. Defects in the STIM1 SOARα2 domain affect multiple steps in the CRAC channel activation cascade. Cell Mol Life Sci 2021; 78:6645-6667. [PMID: 34498097 PMCID: PMC8558294 DOI: 10.1007/s00018-021-03933-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Revised: 08/05/2021] [Accepted: 08/27/2021] [Indexed: 01/05/2023]
Abstract
The calcium release-activated calcium (CRAC) channel consists of STIM1, a Ca2+ sensor in the endoplasmic reticulum (ER), and Orai1, the Ca2+ ion channel in the plasma membrane. Ca2+ store depletion triggers conformational changes and oligomerization of STIM1 proteins and their direct interaction with Orai1. Structural alterations include the transition of STIM1 C-terminus from a folded to an extended conformation thereby exposing CAD (CRAC activation domain)/SOAR (STIM1-Orai1 activation region) for coupling to Orai1. In this study, we discovered that different point mutations of F394 in the small alpha helical segment (STIM1 α2) within the CAD/SOAR apex entail a rich plethora of effects on diverse STIM1 activation steps. An alanine substitution (STIM1 F394A) destabilized the STIM1 quiescent state, as evident from its constitutive activity. Single point mutation to hydrophilic, charged amino acids (STIM1 F394D, STIM1 F394K) impaired STIM1 homomerization and subsequent Orai1 activation. MD simulations suggest that their loss of homomerization may arise from altered formation of the CC1α1-SOAR/CAD interface and potential electrostatic interactions with lipid headgroups in the ER membrane. Consistent with these findings, we provide experimental evidence that the perturbing effects of F394D depend on the distance of the apex from the ER membrane. Taken together, our results suggest that the CAD/SOAR apex is in the immediate vicinity of the ER membrane in the STIM1 quiescent state and that different mutations therein can impact the STIM1/Orai1 activation cascade in various manners. Legend: Upon intracellular Ca2+ store depletion of the endoplasmic reticulum (ER), Ca2+ dissociates from STIM1. As a result, STIM1 adopts an elongated conformation and elicits Ca2+ influx from the extracellular matrix (EM) into the cell due to binding to and activation of Ca2+-selective Orai1 channels (left). The effects of three point mutations within the SOARα2 domain highlight the manifold roles of this region in the STIM1/Orai1 activation cascade: STIM1 F394A is active irrespective of the intracellular ER Ca2+ store level, but activates Orai1 channels to a reduced extent (middle). On the other hand, STIM1 F394D/K cannot adopt an elongated conformation upon Ca2+ store-depletion due to altered formation of the CC1α1-SOAR/CAD interface and/or electrostatic interaction of the respective side-chain charge with corresponding opposite charges on lipid headgroups in the ER membrane (right).
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Affiliation(s)
- Carmen Höglinger
- Institute of Biophysics, Johannes Kepler University Linz, Gruberstrasse 40, 4020, Linz, Austria
| | - Herwig Grabmayr
- Institute of Biophysics, Johannes Kepler University Linz, Gruberstrasse 40, 4020, Linz, Austria
| | - Lena Maltan
- Institute of Biophysics, Johannes Kepler University Linz, Gruberstrasse 40, 4020, Linz, Austria
| | - Ferdinand Horvath
- Institute of Theoretical Physics, Johannes Kepler University Linz, Altenbergerstraße 69, 4040, Linz, Austria
| | - Heinrich Krobath
- Institute of Theoretical Physics, Johannes Kepler University Linz, Altenbergerstraße 69, 4040, Linz, Austria
| | - Martin Muik
- Institute of Biophysics, Johannes Kepler University Linz, Gruberstrasse 40, 4020, Linz, Austria
| | - Adela Tiffner
- Institute of Biophysics, Johannes Kepler University Linz, Gruberstrasse 40, 4020, Linz, Austria
| | - Thomas Renger
- Institute of Theoretical Physics, Johannes Kepler University Linz, Altenbergerstraße 69, 4040, Linz, Austria
| | - Christoph Romanin
- Institute of Biophysics, Johannes Kepler University Linz, Gruberstrasse 40, 4020, Linz, Austria
| | - Marc Fahrner
- Institute of Biophysics, Johannes Kepler University Linz, Gruberstrasse 40, 4020, Linz, Austria.
| | - Isabella Derler
- Institute of Biophysics, Johannes Kepler University Linz, Gruberstrasse 40, 4020, Linz, Austria.
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16
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Wu B, Woo JS, Vila P, Jew M, Leung J, Sun Z, Srikanth S, Gwack Y. NKD2 mediates stimulation-dependent ORAI1 trafficking to augment Ca 2+ entry in T cells. Cell Rep 2021; 36:109603. [PMID: 34433025 PMCID: PMC8435239 DOI: 10.1016/j.celrep.2021.109603] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Revised: 06/21/2021] [Accepted: 08/03/2021] [Indexed: 01/19/2023] Open
Abstract
Sustained activation of the Ca2+-release-activated Ca2+ (CRAC) channel is pivotal for effector T cell responses. The mechanisms underlying this sustainability remain poorly understood. We find that plasma membrane localization of ORAI1, the pore subunit of CRAC channels, is limited in effector T cells, with a significant fraction trapped in intracellular vesicles. From a targeted screen, we identify an essential component of ORAI1+ vesicles, naked cuticle homolog 2 (NKD2). Mechanistically, NKD2, an adaptor molecule activated by signaling pathways downstream of T cell receptors, orchestrates trafficking and insertion of ORAI1+ vesicles to the plasma membrane. Together, our findings suggest that T cell receptor (TCR)-stimulation-dependent insertion of ORAI1 into the plasma membrane is essential for sustained Ca2+ signaling and cytokine production in T cells.
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Affiliation(s)
- Beibei Wu
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles CA 90095, USA
| | - Jin Seok Woo
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles CA 90095, USA
| | - Pamela Vila
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles CA 90095, USA,Present address: Olive View-UCLA Medical Center, 14445 Olive View Drive, Sylmar, CA 91342, USA
| | - Marcus Jew
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles CA 90095, USA,Present address: Ronald Reagan UCLA Medical Center, 757 Westwood Plaza, Los Angeles, CA 90095, USA
| | - Jennifer Leung
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles CA 90095, USA,Present address: Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA
| | - Zuoming Sun
- Department of Molecular Imaging & Therapy, Beckman Research Institute of City of Hope, Duarte, CA 91010, USA
| | - Sonal Srikanth
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles CA 90095, USA.
| | - Yousang Gwack
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles CA 90095, USA.
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17
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Kanellopoulos JM, Almeida-da-Silva CLC, Rüütel Boudinot S, Ojcius DM. Structural and Functional Features of the P2X4 Receptor: An Immunological Perspective. Front Immunol 2021; 12:645834. [PMID: 33897694 PMCID: PMC8059410 DOI: 10.3389/fimmu.2021.645834] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2020] [Accepted: 03/04/2021] [Indexed: 12/14/2022] Open
Abstract
Extracellular nucleotides are important mediators of activation, triggering various responses through plasma membrane P2 and P1 receptors. P2 receptors are further subdivided into ionotropic P2X receptors and G protein-coupled P2Y receptors. P2X4 is an ATP-gated cation channel broadly expressed in most tissues of the body. Within the P2X family, P2X4 has a unique subcellular distribution, being preferentially localized in lysosomes. In these organelles, high ATP concentrations do not trigger P2X4 because of the low pH. However, when the pH increases to 7.4, P2X4 can be stimulated by intra-lysosomal ATP, which is in its active, tetra-anionic form. Elucidation of P2X4, P2X3 and P2X7 structures has shed some light on the functional differences between these purinergic receptors. The potential interaction between P2X4 and P2X7 has been extensively studied. Despite intensive effort, it has not been possible yet to determine whether P2X4 and P2X7 interact as heterotrimers or homotrimers at the plasma membrane. However, several publications have shown that functional interactions between P2X4 and P2X7 do occur. Importantly, these studies indicate that P2X4 potentiates P2X7-dependent activation of inflammasomes, leading to increased release of IL-1β and IL-18. The role of P2X4 in various diseases could be beneficial or deleterious even though the pathophysiological mechanisms involved are still poorly defined. However, in diseases whose physiopathology involves activation of the NLRP3 inflammasome, P2X4 was found to exacerbate severity of disease. The recent production of monoclonal antibodies specific for the human and mouse P2X4, some of which are endowed with agonist or antagonist properties, raises the possibility that they could be used therapeutically. Analysis of single nucleotide polymorphisms of the human P2RX4 gene has uncovered the association of P2RX4 gene variants with susceptibility to several human diseases.
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Affiliation(s)
- Jean M Kanellopoulos
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Saclay, Gif-sur-Yvette, France
| | | | - Sirje Rüütel Boudinot
- Department of Chemistry and Biotechnology, Tallinn University of Technology, Tallinn, Estonia
| | - David M Ojcius
- Department of Biomedical Sciences, University of the Pacific, Arthur A. Dugoni School of Dentistry, San Francisco, CA, United States
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18
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Tiffner A, Maltan L, Fahrner M, Sallinger M, Weiß S, Grabmayr H, Höglinger C, Derler I. Transmembrane Domain 3 (TM3) Governs Orai1 and Orai3 Pore Opening in an Isoform-Specific Manner. Front Cell Dev Biol 2021; 9:635705. [PMID: 33644073 PMCID: PMC7905104 DOI: 10.3389/fcell.2021.635705] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Accepted: 01/21/2021] [Indexed: 12/17/2022] Open
Abstract
STIM1-mediated activation of calcium selective Orai channels is fundamental for life. The three Orai channel isoforms, Orai1-3, together with their multiple ways of interplay, ensure their highly versatile role in a variety of cellular functions and tissues in both, health and disease. While all three isoforms are activated in a store-operated manner by STIM1, they differ in diverse biophysical and structural properties. In the present study, we provide profound evidence that non-conserved residues in TM3 control together with the cytosolic loop2 region the maintenance of the closed state and the configuration of an opening-permissive channel conformation of Orai1 and Orai3 in an isoform-specific manner. Indeed, analogous amino acid substitutions of these non-conserved residues led to distinct extents of gain- (GoF) or loss-of-function (LoF). Moreover, we showed that enhanced overall hydrophobicity along TM3 correlates with an increase in GoF mutant currents. Conclusively, while the overall activation mechanisms of Orai channels appear comparable, there are considerable variations in gating checkpoints crucial for pore opening. The elucidation of regions responsible for isoform-specific functional differences provides valuable targets for drug development selective for one of the three Orai homologs.
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Affiliation(s)
| | | | | | | | | | | | | | - Isabella Derler
- JKU Life Science Center, Institute of Biophysics, Johannes Kepler University Linz, Linz, Austria
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19
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Tiffner A, Schober R, Höglinger C, Bonhenry D, Pandey S, Lunz V, Sallinger M, Frischauf I, Fahrner M, Lindinger S, Maltan L, Berlansky S, Stadlbauer M, Schindl R, Ettrich R, Romanin C, Derler I. CRAC channel opening is determined by a series of Orai1 gating checkpoints in the transmembrane and cytosolic regions. J Biol Chem 2021; 296:100224. [PMID: 33361160 PMCID: PMC7948504 DOI: 10.1074/jbc.ra120.015548] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Revised: 12/15/2020] [Accepted: 12/22/2020] [Indexed: 12/13/2022] Open
Abstract
The initial activation step in the gating of ubiquitously expressed Orai1 calcium (Ca2+) ion channels represents the activation of the Ca2+-sensor protein STIM1 upon Ca2+ store depletion of the endoplasmic reticulum. Previous studies using constitutively active Orai1 mutants gave rise to, but did not directly test, the hypothesis that STIM1-mediated Orai1 pore opening is accompanied by a global conformational change of all Orai transmembrane domain (TM) helices within the channel complex. We prove that a local conformational change spreads omnidirectionally within the Orai1 complex. Our results demonstrate that these locally induced global, opening-permissive TM motions are indispensable for pore opening and require clearance of a series of Orai1 gating checkpoints. We discovered these gating checkpoints in the middle and cytosolic extended TM domain regions. Our findings are based on a library of double point mutants that contain each one loss-of-function with one gain-of-function point mutation in a series of possible combinations. We demonstrated that an array of loss-of-function mutations are dominant over most gain-of-function mutations within the same as well as of an adjacent Orai subunit. We further identified inter- and intramolecular salt-bridge interactions of Orai subunits as a core element of an opening-permissive Orai channel architecture. Collectively, clearance and synergistic action of all these gating checkpoints are required to allow STIM1 coupling and Orai1 pore opening. Our results unravel novel insights in the preconditions of the unique fingerprint of CRAC channel activation, provide a valuable source for future structural resolutions, and help to understand the molecular basis of disease-causing mutations.
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Affiliation(s)
- Adéla Tiffner
- Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, Linz, Austria
| | - Romana Schober
- Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, Linz, Austria
| | - Carmen Höglinger
- Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, Linz, Austria
| | - Daniel Bonhenry
- Center for Nanobiology and Structural Biology, Institute of Microbiology, Czech Academy of Sciences, Nove Hrady, Czechia
| | - Saurabh Pandey
- Center for Nanobiology and Structural Biology, Institute of Microbiology, Czech Academy of Sciences, Nove Hrady, Czechia
| | - Victoria Lunz
- Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, Linz, Austria
| | - Matthias Sallinger
- Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, Linz, Austria
| | - Irene Frischauf
- Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, Linz, Austria
| | - Marc Fahrner
- Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, Linz, Austria
| | - Sonja Lindinger
- Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, Linz, Austria
| | - Lena Maltan
- Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, Linz, Austria
| | - Sascha Berlansky
- Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, Linz, Austria
| | - Michael Stadlbauer
- Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, Linz, Austria
| | - Rainer Schindl
- Gottfried Schatz Research Center, Medical University of Graz, Graz, Austria
| | - Rudiger Ettrich
- College of Biomedical Sciences, Larkin University, Miami, Florida, USA; Faculty of Mathematics and Physics, Charles University, Prague, Czechia; Department of Cellular Biology & Pharmacology, Herbert Wertheim College of Medicine, Florida International University, Miami, Florida, USA
| | - Christoph Romanin
- Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, Linz, Austria
| | - Isabella Derler
- Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, Linz, Austria.
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20
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Zöphel D, Hof C, Lis A. Altered Ca 2+ Homeostasis in Immune Cells during Aging: Role of Ion Channels. Int J Mol Sci 2020; 22:ijms22010110. [PMID: 33374304 PMCID: PMC7794837 DOI: 10.3390/ijms22010110] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Revised: 12/21/2020] [Accepted: 12/22/2020] [Indexed: 12/29/2022] Open
Abstract
Aging is an unstoppable process and begins shortly after birth. Each cell of the organism is affected by the irreversible process, not only with equal density but also at varying ages and with different speed. Therefore, aging can also be understood as an adaptation to a continually changing cellular environment. One of these very prominent changes in age affects Ca2+ signaling. Especially immune cells highly rely on Ca2+-dependent processes and a strictly regulated Ca2+ homeostasis. The intricate patterns of impaired immune cell function may represent a deficit or compensatory mechanisms. Besides, altered immune function through Ca2+ signaling can profoundly affect the development of age-related disease. This review attempts to summarize changes in Ca2+ signaling due to channels and receptors in T cells and beyond in the context of aging.
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Affiliation(s)
| | | | - Annette Lis
- Correspondence: ; Tel.: +49-(0)-06841-1616318; Fax: +49-(0)-6841-1616302
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21
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Tiffner A, Derler I. Molecular Choreography and Structure of Ca 2+ Release-Activated Ca 2+ (CRAC) and K Ca2+ Channels and Their Relevance in Disease with Special Focus on Cancer. MEMBRANES 2020; 10:membranes10120425. [PMID: 33333945 PMCID: PMC7765462 DOI: 10.3390/membranes10120425] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Revised: 12/04/2020] [Accepted: 12/07/2020] [Indexed: 12/16/2022]
Abstract
Ca2+ ions play a variety of roles in the human body as well as within a single cell. Cellular Ca2+ signal transduction processes are governed by Ca2+ sensing and Ca2+ transporting proteins. In this review, we discuss the Ca2+ and the Ca2+-sensing ion channels with particular focus on the structure-function relationship of the Ca2+ release-activated Ca2+ (CRAC) ion channel, the Ca2+-activated K+ (KCa2+) ion channels, and their modulation via other cellular components. Moreover, we highlight their roles in healthy signaling processes as well as in disease with a special focus on cancer. As KCa2+ channels are activated via elevations of intracellular Ca2+ levels, we summarize the current knowledge on the action mechanisms of the interplay of CRAC and KCa2+ ion channels and their role in cancer cell development.
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22
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Shan W, Hu Y, Ding J, Yang X, Lou J, Du Q, Liao Q, Luo L, Xu J, Xie R. Advances in Ca 2+ modulation of gastrointestinal anion secretion and its dysregulation in digestive disorders (Review). Exp Ther Med 2020; 20:8. [PMID: 32934673 PMCID: PMC7471861 DOI: 10.3892/etm.2020.9136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Accepted: 05/22/2020] [Indexed: 11/29/2022] Open
Abstract
Intracellular calcium (Ca2+) is a critical cell signaling component in gastrointestinal (GI) physiology. Cytosolic calcium ([Ca2+]cyt), as a secondary messenger, controls GI epithelial fluid and ion transport, mucus and neuropeptide secretion, as well as synaptic transmission and motility. The key roles of Ca2+ signaling in other types of secretory cell (including those in the airways and salivary glands) are well known. However, its action in GI epithelial secretion and the underlying molecular mechanisms have remained to be fully elucidated. The present review focused on the role of [Ca2+]cyt in GI epithelial anion secretion. Ca2+ signaling regulates the activities of ion channels and transporters involved in GI epithelial ion and fluid transport, including Cl- channels, Ca2+-activated K+ channels, cystic fibrosis (CF) transmembrane conductance regulator and anion/HCO3- exchangers. Previous studies by the current researchers have focused on this field over several years, providing solid evidence that Ca2+ signaling has an important role in the regulation of GI epithelial anion secretion and uncovering underlying molecular mechanisms. The present review is largely based on previous studies by the current researchers and provides an overview of the currently known molecular mechanisms of GI epithelial anion secretion with an emphasis on Ca2+-mediated ion secretion and its dysregulation in GI disorders. In addition, previous studies by the current researchers demonstrated that different regulatory mechanisms are in place for GI epithelial HCO3- and Cl- secretion. An increased understanding of the roles of Ca2+ signaling and its targets in GI anion secretion may lead to the development of novel strategies to inhibit GI diseases, including the enhancement of fluid secretion in CF and protection of the GI mucosa in ulcer diseases.
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Affiliation(s)
- Weixi Shan
- Department of Gastroenterology, The Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou 563003, P.R. China
| | - Yanxia Hu
- Department of Gastroenterology, The Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou 563003, P.R. China
| | - Jianhong Ding
- Department of Gastroenterology, The Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou 563003, P.R. China
| | - Xiaoxu Yang
- Department of Gastroenterology, The Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou 563003, P.R. China
| | - Jun Lou
- Department of Gastroenterology, The Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou 563003, P.R. China
| | - Qian Du
- Department of Gastroenterology, The Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou 563003, P.R. China
| | - Qiushi Liao
- Department of Gastroenterology, The Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou 563003, P.R. China
| | - Lihong Luo
- Department of Oncology and Geriatrics, Traditional Chinese Medicine Hospital of Chishui City, Guizhou 564700, P.R. China
| | - Jingyu Xu
- Department of Gastroenterology, The Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou 563003, P.R. China
| | - Rui Xie
- Department of Gastroenterology, The Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou 563003, P.R. China
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23
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Barak P, Parekh AB. Signaling through Ca 2+ Microdomains from Store-Operated CRAC Channels. Cold Spring Harb Perspect Biol 2020; 12:cshperspect.a035097. [PMID: 31358516 DOI: 10.1101/cshperspect.a035097] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Calcium (Ca2+) ion microdomains are subcellular regions of high Ca2+ concentration that develop rapidly near open Ca2+ channels in the plasma membrane or internal stores and generate local regions of high Ca2+ concentration. These microdomains are remarkably versatile in that they activate a range of responses that differ enormously in both their temporal and spatial profile. In this review, we describe how Ca2+ microdomains generated by store-operated calcium channels, a widespread and conserved Ca2+ entry pathway, stimulate different signaling pathways, and how the spatial extent of a Ca2+ microdomain can be influenced by Ca2+ ATPase pumps.
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Affiliation(s)
- Pradeep Barak
- Department of Physiology, Anatomy, and Genetics, Oxford University, Oxford OX1 3PT, United Kingdom
| | - Anant B Parekh
- Department of Physiology, Anatomy, and Genetics, Oxford University, Oxford OX1 3PT, United Kingdom
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24
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Bendiks L, Geiger F, Gudermann T, Feske S, Dietrich A. Store-operated Ca 2+ entry in primary murine lung fibroblasts is independent of classical transient receptor potential (TRPC) channels and contributes to cell migration. Sci Rep 2020; 10:6812. [PMID: 32321939 PMCID: PMC7176639 DOI: 10.1038/s41598-020-63677-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Accepted: 03/16/2020] [Indexed: 12/14/2022] Open
Abstract
Stromal interaction molecules (STIM1, 2) are acting as sensors for Ca2+ in intracellular stores and activate Orai channels at the plasma membrane for store-operated Ca2+ entry (SOCE), while classical transient receptor potential (TRPC) channel mediate receptor-operated Ca2+ entry (ROCE). Several reports, however, indicate a role for TRPC in SOCE in certain cell types. Here, we analyzed Ca2+ influx and cell function in TRPC1/6-deficient (TRPC1/6-/-) and STIM1/2- deficient (STIM1/2ΔpmLF) primary murine lung fibroblasts (pmLF). As expected, SOCE was decreased in STIM1/2- deficient pmLF and ROCE was decreased in TRPC1/6-/- pmLF compared to control cells. By contrast, SOCE was not significantly different in TRPC1/6-/- pmLF and ROCE was similar in STIM1/2-deficient pmLF compared to Wt cells. Most interestingly, cell proliferation, migration and nuclear localization of nuclear factor of activated T-cells (NFATc1 and c3) were decreased after ablation of STIM1/2 proteins in pmLF. In conclusion, TRPC1/6 channels are not involved in SOCE and STIM1/2 deficiency resulted in decreased cell proliferation and migration in pmLF.
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Affiliation(s)
- Larissa Bendiks
- Walther Straub Institute of Pharmacology and Toxicology, Member of the German Center for Lung Research (DZL), Medical Faculty, LMU-Munich, Munich, Germany
| | - Fabienne Geiger
- Walther Straub Institute of Pharmacology and Toxicology, Member of the German Center for Lung Research (DZL), Medical Faculty, LMU-Munich, Munich, Germany
| | - Thomas Gudermann
- Walther Straub Institute of Pharmacology and Toxicology, Member of the German Center for Lung Research (DZL), Medical Faculty, LMU-Munich, Munich, Germany
| | - Stefan Feske
- Department of Pathology, New York University School of Medicine, New York, NY, 10016, USA
| | - Alexander Dietrich
- Walther Straub Institute of Pharmacology and Toxicology, Member of the German Center for Lung Research (DZL), Medical Faculty, LMU-Munich, Munich, Germany.
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25
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He L, Raddatz AD, Zhou F, Hwang H, Kemp ML, Lu H. Dynamic Mitochondrial Migratory Features Associated with Calcium Responses during T Cell Antigen Recognition. THE JOURNAL OF IMMUNOLOGY 2019; 203:760-768. [PMID: 31201236 DOI: 10.4049/jimmunol.1800299] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Accepted: 05/20/2019] [Indexed: 01/09/2023]
Abstract
A T cell clone is able to distinguish Ags in the form of peptide-MHC complexes with high specificity and sensitivity; however, how subtle differences in peptide-MHC structures translate to distinct T cell effector functions remains unknown. We hypothesized that mitochondrial positioning and associated calcium responses play an important role in T cell Ag recognition. We engineered a microfluidic system to precisely manipulate and synchronize a large number of cell-cell pairing events, which provided simultaneous real-time signaling imaging and organelle tracking with temporal precision. In addition, we developed image-derived metrics to quantify calcium response and mitochondria movement. Using myelin proteolipid altered peptide ligands and a hybridoma T cell line derived from a mouse model of experimental autoimmune encephalomyelitis, we observed that Ag potency modulates calcium response at the single-cell level. We further developed a partial least squares regression model, which highlighted mitochondrial positioning as a strong predictor of calcium response. The model revealed T cell mitochondria sharply alter direction within minutes following exposure to agonist peptide Ag, changing from accumulation at the immunological synapse to retrograde movement toward the distal end of the T cell body. By quantifying mitochondria movement as a highly dynamic process with rapidly changing phases, our result reconciles conflicting prior reports of mitochondria positioning during T cell Ag recognition. We envision applying this pipeline of methodology to study cell interactions between other immune cell types to reveal important signaling phenomenon that is inaccessible because of data-limited experimental design.
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Affiliation(s)
- Luye He
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA 30332
| | - Andrew D Raddatz
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA 30332
| | - Fangyuan Zhou
- Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332; and
| | - Hyundoo Hwang
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA 30332
| | - Melissa L Kemp
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA 30332; .,Interdisciplinary Program in Bioengineering, Georgia Institute of Technology, Atlanta, GA 30332
| | - Hang Lu
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA 30332; .,Interdisciplinary Program in Bioengineering, Georgia Institute of Technology, Atlanta, GA 30332
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26
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Zhang S, Al-Maghout T, Cao H, Pelzl L, Salker MS, Veldhoen M, Cheng A, Lang F, Singh Y. Gut Bacterial Metabolite Urolithin A (UA) Mitigates Ca 2+ Entry in T Cells by Regulating miR-10a-5p. Front Immunol 2019; 10:1737. [PMID: 31417547 PMCID: PMC6685097 DOI: 10.3389/fimmu.2019.01737] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Accepted: 07/09/2019] [Indexed: 12/16/2022] Open
Abstract
The gut microbiota influences several biological functions including immune responses. Inflammatory bowel disease is favorably influenced by consumption of several dietary natural plant products such as pomegranate, walnuts, and berries containing polyphenolic compounds such as ellagitannins and ellagic acid. The gut microbiota metabolizes ellagic acid resulting in the formation of bioactive urolithins A, B, C, and D. Urolithin A (UA) is the most active and effective gut metabolite and acts as a potent anti-inflammatory and anti-oxidant agent. However, whether gut metabolite UA affects the function of immune cells remains incompletely understood. T cell proliferation is stimulated by store operated Ca2+ entry (SOCE) resulting from stimulation of Orai1 by STIM1/STIM2. We show here that treatment of murine CD4+ T cells with UA (10 μM, 3 days) significantly blunted SOCE in CD4+ T cells, an effect paralleled by significant downregulation of Orai1 and STIM1/2 transcript levels and protein abundance. UA treatment further increased miR-10a-5p abundance in CD4+ T cells in a dose dependent fashion. Overexpression of miR-10a-5p significantly decreased STIM1/2 and Orai1 mRNA and protein levels as well as SOCE in CD4+ T cells. UA further decreased CD4+ T cell proliferation. Thus, the gut bacterial metabolite UA increases miR-10a-5p levels thereby downregulating Orai1/STIM1/STIM2 expression, store operated Ca2+ entry, and proliferation of murine CD4+ T cells.
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Affiliation(s)
- Shaqiu Zhang
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
- Department of Physiology, University of Tübingen, Tübingen, Germany
| | - Tamer Al-Maghout
- Department of Physiology, University of Tübingen, Tübingen, Germany
| | - Hang Cao
- Department of Physiology, University of Tübingen, Tübingen, Germany
| | - Lisann Pelzl
- Department of Physiology, University of Tübingen, Tübingen, Germany
- Centre for Clinical Transfusion Medicine, Tübingen University, Tübingen, Germany
| | - Madhuri S. Salker
- Research Institute of Women's Health, University of Tübingen, Tübingen, Germany
| | - Marc Veldhoen
- Instituto de Medicina Molecular, Joâo Lobo Antunes, Faculdade de Medicina da Universidade de Lisboa, Lisbon, Portugal
| | - Anchun Cheng
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Florian Lang
- Department of Physiology, University of Tübingen, Tübingen, Germany
| | - Yogesh Singh
- Department of Physiology, University of Tübingen, Tübingen, Germany
- Institute of Medical Genetics and Applied Genomics, Tübingen University, Tübingen, Germany
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27
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Gudlur A, Zeraik AE, Hirve N, Hogan PG. STIM calcium sensing and conformational change. J Physiol 2019; 598:1695-1705. [PMID: 31228261 DOI: 10.1113/jp276524] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Accepted: 05/15/2019] [Indexed: 11/08/2022] Open
Abstract
The control of calcium influx at the plasma membrane by endoplasmic reticulum (ER) calcium stores, a process common to invertebrates and vertebrates, is central to physiological calcium signalling and cellular calcium balance. Stromal interaction molecule 1 (STIM1) is a calcium sensor and regulatory protein localized to the ER. ORAI1 is a calcium channel in the plasma membrane (PM). In outline, STIM1 senses an ER-luminal calcium decrease, relocalizes to ER-PM junctions, and recruits and gates ORAI1 channels. Recent work, reviewed here, has offered detailed insight into the process of sensing and communicating ER calcium-store depletion, and particularly into the STIM1 conformational change that is the basis for communication between the ER and the PM.
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Affiliation(s)
- Aparna Gudlur
- Division of Signaling and Gene Expression, La Jolla Institute for Immunology, La Jolla, CA, 92037, USA
| | - Ana Eliza Zeraik
- Division of Signaling and Gene Expression, La Jolla Institute for Immunology, La Jolla, CA, 92037, USA.,Instituto de Física de São Carlos, Universidade de São Paulo, São Carlos, SP, Brasil
| | - Nupura Hirve
- Division of Signaling and Gene Expression, La Jolla Institute for Immunology, La Jolla, CA, 92037, USA
| | - Patrick G Hogan
- Division of Signaling and Gene Expression, La Jolla Institute for Immunology, La Jolla, CA, 92037, USA.,Program in Immunology, University of California-San Diego, La Jolla, CA, 92037, USA.,Moores Cancer Center, University of California-San Diego, La Jolla, CA, 92093, USA
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28
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Butorac C, Muik M, Derler I, Stadlbauer M, Lunz V, Krizova A, Lindinger S, Schober R, Frischauf I, Bhardwaj R, Hediger MA, Groschner K, Romanin C. A novel STIM1-Orai1 gating interface essential for CRAC channel activation. Cell Calcium 2019; 79:57-67. [PMID: 30831274 DOI: 10.1016/j.ceca.2019.02.009] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Revised: 02/19/2019] [Accepted: 02/20/2019] [Indexed: 11/30/2022]
Abstract
Calcium signalling through store-operated calcium (SOC) entry is of crucial importance for T-cell activation and the adaptive immune response. This entry occurs via the prototypic Ca2+ release-activated Ca2+ (CRAC) channel. STIM1, a key molecular component of this process, is located in the membrane of the endoplasmic reticulum (ER) and is initially activated upon Ca2+ store depletion. This activation signal is transmitted to the plasma membrane via a direct physical interaction that takes place between STIM1 and the highly Ca2+-selective ion channel Orai1. The activation of STIM1 induces an extended cytosolic conformation. This, in turn, exposes the CAD/SOAR domain and leads to the formation of STIM1 oligomers. In this study, we focused on a small helical segment (STIM1 α3, aa 400-403), which is located within the CAD/SOAR domain. We determined this segment's specific functional role in terms of STIM1 activation and Orai1 gating. The STIM1 α3 domain appears not essential for STIM1 to interact with Orai1. Instead, it represents a key domain that conveys STIM1 interaction into Orai1 channel gating. The results of cysteine crosslinking experiments revealed the close proximity of STIM1 α3 to a region within Orai1, which was located at the cytosolic extension of transmembrane helix 3, forming a STIM1-Orai1 gating interface (SOGI). We suggest that the interplay between STIM1 α3 and Orai1 TM3 allows STIM1 coupling to be transmitted into physiological CRAC channel activation.
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Affiliation(s)
- Carmen Butorac
- Institute of Biophysics, Johannes Kepler University Linz, Gruberstrasse 40, 4020 Linz, Austria
| | - Martin Muik
- Institute of Biophysics, Johannes Kepler University Linz, Gruberstrasse 40, 4020 Linz, Austria
| | - Isabella Derler
- Institute of Biophysics, Johannes Kepler University Linz, Gruberstrasse 40, 4020 Linz, Austria
| | - Michael Stadlbauer
- Institute of Biophysics, Johannes Kepler University Linz, Gruberstrasse 40, 4020 Linz, Austria
| | - Victoria Lunz
- Institute of Biophysics, Johannes Kepler University Linz, Gruberstrasse 40, 4020 Linz, Austria
| | - Adéla Krizova
- Institute of Biophysics, Johannes Kepler University Linz, Gruberstrasse 40, 4020 Linz, Austria
| | - Sonja Lindinger
- Institute of Biophysics, Johannes Kepler University Linz, Gruberstrasse 40, 4020 Linz, Austria
| | - Romana Schober
- Institute of Biophysics, Johannes Kepler University Linz, Gruberstrasse 40, 4020 Linz, Austria
| | - Irene Frischauf
- Institute of Biophysics, Johannes Kepler University Linz, Gruberstrasse 40, 4020 Linz, Austria
| | - Rajesh Bhardwaj
- Institute of Biochemistry and Molecular Medicine, University of Bern, Buehlstrasse 28, CH-3012 Bern, Switzerland
| | - Matthias A Hediger
- Institute of Biochemistry and Molecular Medicine, University of Bern, Buehlstrasse 28, CH-3012 Bern, Switzerland
| | - Klaus Groschner
- Gottfried Schatz Forschungszentrum, Medizinische Universität Graz, Neue Stiftingtalstraße 6, 8010 Graz, Austria
| | - Christoph Romanin
- Institute of Biophysics, Johannes Kepler University Linz, Gruberstrasse 40, 4020 Linz, Austria.
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29
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Bramini M, Chiacchiaretta M, Armirotti A, Rocchi A, Kale DD, Martin C, Vázquez E, Bandiera T, Ferroni S, Cesca F, Benfenati F. An Increase in Membrane Cholesterol by Graphene Oxide Disrupts Calcium Homeostasis in Primary Astrocytes. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2019; 15:e1900147. [PMID: 30891923 DOI: 10.1002/smll.201900147] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Revised: 02/18/2019] [Indexed: 05/24/2023]
Abstract
The use of graphene nanomaterials (GNMs) for biomedical applications targeted to the central nervous system is exponentially increasing, although precise information on their effects on brain cells is lacking. In this work, the molecular changes induced in cortical astrocytes by few-layer graphene (FLG) and graphene oxide (GO) flakes are addressed. The results show that exposure to FLG/GO does not affect cell viability or proliferation. However, proteomic and lipidomic analyses unveil alterations in several cellular processes, including intracellular Ca2+ ([Ca2+ ]i ) homeostasis and cholesterol metabolism, which are particularly intense in cells exposed to GO. Indeed, GO exposure impairs spontaneous and evoked astrocyte [Ca2+ ]i signals and induces a marked increase in membrane cholesterol levels. Importantly, cholesterol depletion fully rescues [Ca2+ ]i dynamics in GO-treated cells, indicating a causal relationship between these GO-mediated effects. The results indicate that exposure to GNMs alters intracellular signaling in astrocytes and may impact astrocyte-neuron interactions.
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Affiliation(s)
- Mattia Bramini
- Center for Synaptic Neuroscience and Technology and Graphene Labs, Istituto Italiano di Tecnologia, 16132, Genova, Italy
- IRCCS Ospedale Policlinico San Martino, 16132, Genova, Italy
| | - Martina Chiacchiaretta
- Center for Synaptic Neuroscience and Technology and Graphene Labs, Istituto Italiano di Tecnologia, 16132, Genova, Italy
| | - Andrea Armirotti
- Analytical Chemistry Lab and Graphene Labs, Istituto Italiano di Tecnologia, 16163, Genova, Italy
| | - Anna Rocchi
- Center for Synaptic Neuroscience and Technology and Graphene Labs, Istituto Italiano di Tecnologia, 16132, Genova, Italy
- IRCCS Ospedale Policlinico San Martino, 16132, Genova, Italy
| | - Deepali D Kale
- PharmaChemistry Line and Graphene Labs, Istituto Italiano di Tecnologia, 16163, Genova, Italy
| | - Cristina Martin
- Departamento de Química Orgánica, Instituto Regional de Investigación Científica Aplicada (IRICA), Universidad de Castilla La-Mancha, 13071, Ciudad Real, Spain
| | - Ester Vázquez
- Departamento de Química Orgánica, Instituto Regional de Investigación Científica Aplicada (IRICA), Universidad de Castilla La-Mancha, 13071, Ciudad Real, Spain
| | - Tiziano Bandiera
- PharmaChemistry Line and Graphene Labs, Istituto Italiano di Tecnologia, 16163, Genova, Italy
| | - Stefano Ferroni
- Department of Pharmacy and Biotechnology, University of Bologna, 40126, Bologna, Italy
| | - Fabrizia Cesca
- Center for Synaptic Neuroscience and Technology and Graphene Labs, Istituto Italiano di Tecnologia, 16132, Genova, Italy
- Department of Life Sciences, University of Trieste, 34127, Trieste, Italy
| | - Fabio Benfenati
- Center for Synaptic Neuroscience and Technology and Graphene Labs, Istituto Italiano di Tecnologia, 16132, Genova, Italy
- IRCCS Ospedale Policlinico San Martino, 16132, Genova, Italy
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30
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Lunz V, Romanin C, Frischauf I. STIM1 activation of Orai1. Cell Calcium 2019; 77:29-38. [PMID: 30530091 DOI: 10.1016/j.ceca.2018.11.009] [Citation(s) in RCA: 65] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Revised: 11/20/2018] [Accepted: 11/28/2018] [Indexed: 11/23/2022]
Abstract
A primary calcium (Ca2+) entry pathway into non-excitable cells is through the store-operated Ca2+ release activated Ca2+ (CRAC) channel. Ca2+ entry into cells is responsible for the initiation of diverse signalling cascades that affect essential cellular processes like gene regulation, cell growth and death, secretion and gene transcription. Upon depletion of intracellular Ca2+ stores within the endoplasmic reticulum (ER), the CRAC channel opens to refill depleted stores. The two key limiting molecular players of the CRAC channel are the stromal interaction molecule (STIM1) embedded in the ER-membrane and Orai1, residing in the plasma membrane (PM), respectively. Together, they form a highly Ca2+ selective ion channel complex. STIM1 senses the Ca2+ content of the ER and confers Ca2+ store-depletion into the opening of Orai1 channels in the PM for triggering Ca2+-dependent gene transcription, T-cell activation or mast cell degranulation. The interplay of Orai and STIM proteins in the CRAC channel signalling cascade has been the main focus of research for more than twelve years. This chapter focuses on current knowledge and main experimental advances in the understanding of Orai1 activation by STIM1, thereby portraying key mechanistic steps in the CRAC channel signalling cascade.
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Affiliation(s)
- Victoria Lunz
- Institute of Biophysics, Johannes Kepler University Linz, A-4020, Linz, Austria
| | - Christoph Romanin
- Institute of Biophysics, Johannes Kepler University Linz, A-4020, Linz, Austria.
| | - Irene Frischauf
- Institute of Biophysics, Johannes Kepler University Linz, A-4020, Linz, Austria.
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31
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EGR-mediated control of STIM expression and function. Cell Calcium 2018; 77:58-67. [PMID: 30553973 DOI: 10.1016/j.ceca.2018.12.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Revised: 12/03/2018] [Accepted: 12/04/2018] [Indexed: 12/22/2022]
Abstract
Ca2+ is a ubiquitous, dynamic and pluripotent second messenger with highly context-dependent roles in complex cellular processes such as differentiation, proliferation, and cell death. These Ca2+ signals are generated by Ca2+-permeable channels located on the plasma membrane (PM) and endoplasmic reticulum (ER) and shaped by PM- and ER-localized pumps and transporters. Differences in the expression of these Ca2+ homeostasis proteins contribute to cell and context-dependent differences in the spatiotemporal organization of Ca2+ signals and, ultimately, cell fate. This review focuses on the Early Growth Response (EGR) family of zinc finger transcription factors and their role in the transcriptional regulation of Stromal Interaction Molecule (STIM1), a critical regulator of Ca2+ entry in both excitable and non-excitable cells.
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32
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High-Resolution Imaging of STIM/Orai Subcellular Localization Using Array Confocal Laser Scanning Microscopy. Methods Mol Biol 2018. [PMID: 30203287 DOI: 10.1007/978-1-4939-8704-7_15] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
The expression of chimeras that consist of a fluorescent protein (FP) conjugated with a protein of interest provides the ability to visualize, track, and quantify the subcellular localization and dynamics of specific proteins in biological samples. Array confocal laser scanning microscopy is an eminently suitable technique for live-cell imaging of FP-tagged fusion proteins. Here, we describe real-time monitoring of the subcellular dynamics of the stromal-interacting molecule 1 (STIM1) and Orai1, the key protagonists of store-operated Ca2+ entry (SOCE) under resting conditions, and upon Ca2+ mobilization from the endoplasmic reticulum (ER).
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33
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Tam KC, Ali E, Hua J, Chataway T, Barritt GJ. Evidence for the interaction of peroxiredoxin-4 with the store-operated calcium channel activator STIM1 in liver cells. Cell Calcium 2018; 74:14-28. [PMID: 29804005 DOI: 10.1016/j.ceca.2018.05.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2018] [Revised: 05/04/2018] [Accepted: 05/12/2018] [Indexed: 12/22/2022]
Abstract
Ca2+ entry through store-operated Ca2+ channels (SOCs) in the plasma membrane (PM) of hepatocytes plays a central role in the hormonal regulation of liver metabolism. SOCs are composed of Orai1, the channel pore protein, and STIM1, the activator protein, and are regulated by hormones and reactive oxygen species (ROS). In addition to Orai1, STIM1 also interacts with several other intracellular proteins. Most previous studies of the cellular functions of Orai1 and STIM1 have employed immortalised cells in culture expressing ectopic proteins tagged with a fluorescent polypeptide such as GFP. Little is known about the intracellular distributions of endogenous Orai1 and STIM1. The aims are to determine the intracellular distribution of endogenous Orai1 and STIM1 in hepatocytes and to identify novel STIM1 binding proteins. Subcellular fractions of rat liver were prepared by homogenisation and differential centrifugation. Orai1 and STIM1 were identified and quantified by western blot. Orai1 was found in the PM (0.03%), heavy (44%) and light (27%) microsomal fractions, and STIM1 in the PM (0.09%), and heavy (85%) and light (13%) microsomal fractions. Immunoprecipitation of STIM1 followed by LC/MS or western blot identified peroxiredoxin-4 (Prx-4) as a potential STIM1 binding protein. Prx-4 was found principally in the heavy microsomal fraction. Knockdown of Prx-4 using siRNA, or inhibition of Prx-4 using conoidin A, did not affect Ca2+ entry through SOCs but rendered SOCs susceptible to inhibition by H2O2. It is concluded that, in hepatocytes, a considerable proportion of endogenous Orai1 and STIM1 is located in the rough ER. In the rough ER, STIM1 interacts with Prx-4, and this interaction may contribute to the regulation by ROS of STIM1 and SOCs.
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Affiliation(s)
- Ka Cheung Tam
- Discipline of Medical Biochemistry, College of Medicine and Public Health, Flinders University, Adelaide, South Australia, 5001, Australia
| | - Eunus Ali
- Discipline of Medical Biochemistry, College of Medicine and Public Health, Flinders University, Adelaide, South Australia, 5001, Australia
| | - Jin Hua
- Discipline of Medical Biochemistry, College of Medicine and Public Health, Flinders University, Adelaide, South Australia, 5001, Australia
| | - Tim Chataway
- Discipline of Medical Biochemistry, College of Medicine and Public Health, Flinders University, Adelaide, South Australia, 5001, Australia
| | - Greg J Barritt
- Discipline of Medical Biochemistry, College of Medicine and Public Health, Flinders University, Adelaide, South Australia, 5001, Australia.
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Choi H, Srikanth S, Atti E, Pirih FQ, Nervina JM, Gwack Y, Tetradis S. Deletion of Orai1 leads to bone loss aggravated with aging and impairs function of osteoblast lineage cells. Bone Rep 2018; 8:147-155. [PMID: 29955633 PMCID: PMC6020256 DOI: 10.1016/j.bonr.2018.03.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Revised: 03/21/2018] [Accepted: 03/22/2018] [Indexed: 02/02/2023] Open
Abstract
Osteoblast lineage cells, a group of cells including mesenchymal progenitors, osteoblasts, and osteocytes, are tightly controlled for differentiation, proliferation and stage-specific functions in processes of skeletal development, growth and maintenance. Recently, the plasma membrane calcium channel Orai1 was highlighted for its role in skeletal development and osteoblast differentiation. Yet the roles of Orai1 in osteoblast lineage cells at various stages of maturation have not been investigated. Herein we report the severe bone loss that occurred in Orai1−/− mice, aggravated by aging, as shown by the microcomputed tomography (mCT) and bone histomorphometry analysis of 8-week and 12-week old Orai1−/− mice and sex-matched WT littermates. We also report that Orai1 deficiency affected the differentiation, proliferation, and type I collagen secretion of primary calvarial osteoblasts, mesenchymal progenitors, and osteocytes in Orai1−/− mice; specifically, our study revealed a significant decrease in the expression of osteocytic genes Fgf23, DMP1 and Phex in the cortical long bone of Orai1−/− mice; a defective cellular and nuclear morphology of Orai1−/− osteocytes; and defective osteogenic differentiation of Orai1−/− primary calvarial osteoblasts (pOBs), including a decrease in extracellular-secretion of type I collagen. An increase in the mesenchymal progenitor population of Orai1−/− bone marrow cells was indicated by a colony forming unit-fibroblasts (CFU-F) assay, and the increased proliferation of Orai1−/− pOBs was indicated by an MTT assay. Notably, Orai1 deficiency reduced the nuclear localization and transcription activity of the Nuclear Factor of Activated T-cell c1 (NFATc1), a calcium-regulated transcription factor, in pOBs. Altogether, our study demonstrated the crucial role of Orai1 in bone development and maintenance, via its diverse effects on osteoblast lineage cells from mesenchymal progenitors to osteocytes. Severe bone loss in adult Orai1-/- mice was aggravated by aging. Orai1 deficiency affected function, differentiation and proliferation of osteoblast lineage cells, from mesenchymal progenitors to and osteocytes. Orai1 deficiency reduced the nuclear localization and transcription activity of NFATc1, a calcium-regulated transcription factor, in primary calvarial osteoblasts.
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Affiliation(s)
- Hyewon Choi
- Division of Oral Biology and Medicine, School of Dentistry, University of California at Los Angeles, 10833 Le Conte Ave., Los Angeles, CA 90095-1668, United States
| | - Sonal Srikanth
- Department of Physiology, David Geffen School of Medicine, University of California at Los Angeles, 10833 Le Conte Avenue, Los Angeles, CA 90095-1751, United States
| | - Elisa Atti
- Division of Oral Biology and Medicine, School of Dentistry, University of California at Los Angeles, 10833 Le Conte Ave., Los Angeles, CA 90095-1668, United States
| | - Flavia Q Pirih
- Section of Periodontics, School of Dentistry, University of California at Los Angeles, 10833 Le Conte Ave., Los Angeles, CA 90095-1668, United States
| | - Jeanne M Nervina
- Section of Orthodontics, School of Dentistry, University of California at Los Angeles, 10833 Le Conte Ave., Los Angeles, CA 90095-1668, United States
| | - Yousang Gwack
- Department of Physiology, David Geffen School of Medicine, University of California at Los Angeles, 10833 Le Conte Avenue, Los Angeles, CA 90095-1751, United States
| | - Sotirios Tetradis
- Division of Diagnostic and Surgical Sciences, School of Dentistry, University of California at Los Angeles, 10833 Le Conte Ave., Los Angeles, CA 90095-1668, United States
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Derler I, Butorac C, Krizova A, Stadlbauer M, Muik M, Fahrner M, Frischauf I, Romanin C. Authentic CRAC channel activity requires STIM1 and the conserved portion of the Orai N terminus. J Biol Chem 2018; 293:1259-1270. [PMID: 29237734 PMCID: PMC5787803 DOI: 10.1074/jbc.m117.812206] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Revised: 11/23/2017] [Indexed: 11/06/2022] Open
Abstract
Calcium (Ca2+) is an essential second messenger required for diverse signaling processes in immune cells. Ca2+ release-activated Ca2+ (CRAC) channels represent one main Ca2+ entry pathway into the cell. They are fully reconstituted via two proteins, the stromal interaction molecule 1 (STIM1), a Ca2+ sensor in the endoplasmic reticulum, and the Ca2+ ion channel Orai in the plasma membrane. After Ca2+ store depletion, STIM1 and Orai couple to each other, allowing Ca2+ influx. CRAC-/STIM1-mediated Orai channel currents display characteristic hallmarks such as high Ca2+ selectivity, an increase in current density when switching from a Ca2+-containing solution to a divalent-free Na+ one, and fast Ca2+-dependent inactivation. Here, we discovered several constitutively active Orai1 and Orai3 mutants, containing substitutions in the TM3 and/or TM4 regions, all of which displayed a loss of the typical CRAC channel hallmarks. Restoring authentic CRAC channel activity required both the presence of STIM1 and the conserved Orai N-terminal portion. Similarly, these structural requisites were found in store-operated Orai channels. Key molecular determinants within the Orai N terminus that together with STIM1 maintained the typical CRAC channel hallmarks were distinct from those that controlled store-dependent Orai activation. In conclusion, the conserved portion of the Orai N terminus is essential for STIM1, as it fine-tunes the open Orai channel gating, thereby establishing authentic CRAC channel activity.
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Affiliation(s)
- Isabella Derler
- From the Institute of Biophysics, Johannes Kepler University of Linz, Gruberstrasse 40, 4020 Linz, Austria
| | - Carmen Butorac
- From the Institute of Biophysics, Johannes Kepler University of Linz, Gruberstrasse 40, 4020 Linz, Austria
| | - Adéla Krizova
- From the Institute of Biophysics, Johannes Kepler University of Linz, Gruberstrasse 40, 4020 Linz, Austria
| | - Michael Stadlbauer
- From the Institute of Biophysics, Johannes Kepler University of Linz, Gruberstrasse 40, 4020 Linz, Austria
| | - Martin Muik
- From the Institute of Biophysics, Johannes Kepler University of Linz, Gruberstrasse 40, 4020 Linz, Austria
| | - Marc Fahrner
- From the Institute of Biophysics, Johannes Kepler University of Linz, Gruberstrasse 40, 4020 Linz, Austria
| | - Irene Frischauf
- From the Institute of Biophysics, Johannes Kepler University of Linz, Gruberstrasse 40, 4020 Linz, Austria
| | - Christoph Romanin
- From the Institute of Biophysics, Johannes Kepler University of Linz, Gruberstrasse 40, 4020 Linz, Austria
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36
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Dong TX, Othy S, Greenberg ML, Jairaman A, Akunwafo C, Leverrier S, Yu Y, Parker I, Dynes JL, Cahalan MD. Intermittent Ca 2+ signals mediated by Orai1 regulate basal T cell motility. eLife 2017; 6:27827. [PMID: 29239723 PMCID: PMC5747518 DOI: 10.7554/elife.27827] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2017] [Accepted: 11/06/2017] [Indexed: 12/20/2022] Open
Abstract
Ca2+ influx through Orai1 channels is crucial for several T cell functions, but a role in regulating basal cellular motility has not been described. Here, we show that inhibition of Orai1 channel activity increases average cell velocities by reducing the frequency of pauses in human T cells migrating through confined spaces, even in the absence of extrinsic cell contacts or antigen recognition. Utilizing a novel ratiometric genetically encoded cytosolic Ca2+ indicator, Salsa6f, which permits real-time monitoring of cytosolic Ca2+ along with cell motility, we show that spontaneous pauses during T cell motility in vitro and in vivo coincide with episodes of cytosolic Ca2+ signaling. Furthermore, lymph node T cells exhibited two types of spontaneous Ca2+ transients: short-duration 'sparkles' and longer duration global signals. Our results demonstrate that spontaneous and self-peptide MHC-dependent activation of Orai1 ensures random walk behavior in T cells to optimize immune surveillance.
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Affiliation(s)
- Tobias X Dong
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, United States
| | - Shivashankar Othy
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, United States
| | - Milton L Greenberg
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, United States
| | - Amit Jairaman
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, United States
| | - Chijioke Akunwafo
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, United States
| | - Sabrina Leverrier
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, United States
| | - Ying Yu
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, United States
| | - Ian Parker
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, United States.,Department of Neurobiology and Behavior, University of California, Irvine, Irvine, United States
| | - Joseph L Dynes
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, United States
| | - Michael D Cahalan
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, United States.,Institute for Immunology, University of California, Irvine, Irvine, United States
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Epigallocatechin-3-gallate (EGCG) up-regulates miR-15b expression thus attenuating store operated calcium entry (SOCE) into murine CD4 + T cells and human leukaemic T cell lymphoblasts. Oncotarget 2017; 8:89500-89514. [PMID: 29163766 PMCID: PMC5685687 DOI: 10.18632/oncotarget.20032] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Accepted: 07/26/2017] [Indexed: 02/05/2023] Open
Abstract
CD4+ T cells are key elements in immune responses and inflammation. Activation of T cell receptors in CD4+ T cells triggers cytosolic Ca2+ release with subsequent store operated Ca2+ entry (SOCE), which is accomplished by the pore forming Ca2+ release activated Ca2+ (CRAC) channel Orai1 and its regulator stromal cell-interaction molecule 2 (STIM2). Green tea polyphenol epigallocatechin-3-gallate (EGCG) acts as a potent anti-inflammatory and anti-oxidant agent for various types of cells including immune cells. However, how post-transcriptional gene regulators such as miRNAs are involved in the regulation of Ca2+ influx into murine CD4+ T cells and human Jurkat T cells through EGCG is not defined. EGCG treatment of murine CD4+ T cells significantly down-regulated the expression of STIM2 and Orai1 both at mRNA and protein levels. Furthermore, EGCG significantly decreased SOCE in both murine and human T cells. EGCG treatment increased miRNA-15b (miR-15b) abundance in both murine and human T cells. Bioinformatics analysis reveals that miR-15b, which has a STIM2 binding site, is involved in the down-regulation of SOCE. Overexpression of miR-15b significantly decreased the mRNA and protein expression of STIM2 and Orai1 in murine T cells. Treatment of Jurkat T cells with 10 μM EGCG further decreased mTOR and PTEN protein levels. EGCG decreased mitochondrial membrane potential (MMP) in both human and murine T cells. In conclusion, the observations suggest that EGCG inhibits the Ca2+ entry into murine and human T cells, an effect accomplished at least in part by up-regulation of miR-15b.
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Korzeniowski MK, Wisniewski E, Baird B, Holowka DA, Balla T. Molecular anatomy of the early events in STIM1 activation - oligomerization or conformational change? J Cell Sci 2017; 130:2821-2832. [PMID: 28724757 DOI: 10.1242/jcs.205583] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Accepted: 07/11/2017] [Indexed: 12/19/2022] Open
Abstract
Decreased luminal endoplasmic reticulum (ER) Ca2+ concentration triggers oligomerization and clustering of the ER Ca2+ sensor STIM1 to promote its association with plasma membrane Orai1 Ca2+ channels leading to increased Ca2+ influx. A key step in STIM1 activation is the release of its SOAR domain from an intramolecular clamp formed with the STIM1 first coiled-coil (CC1) region. Using a truncated STIM1(1-343) molecule that captures or releases the isolated SOAR domain depending on luminal ER Ca2+ concentrations, we analyzed the early molecular events that control the intramolecular clamp formed between the CC1 and SOAR domains. We found that STIM1 forms constitutive dimers, and its CC1 domain can bind the SOAR domain of another STIM1 molecule in trans. Artificial oligomerization failed to liberate the SOAR domain or activate STIM1 unless the luminal Ca2+-sensing domains were removed. We propose that the release of SOAR from its CC1 interaction is controlled by changes in the orientation of the two CC1 domains in STIM1 dimers. Ca2+ unbinding in the STIM1 luminal domains initiates the conformational change allowing SOAR domain liberation and clustering, leading to Orai1 channel activation.
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Affiliation(s)
- Marek K Korzeniowski
- Section on Molecular Signal Transduction, Program for Developmental Neuroscience, Eunice Kennedy Shriver NICHD, National Institutes of Health, Bethesda, MD 20892, USA.,Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA
| | - Eva Wisniewski
- Section on Molecular Signal Transduction, Program for Developmental Neuroscience, Eunice Kennedy Shriver NICHD, National Institutes of Health, Bethesda, MD 20892, USA
| | - Barbara Baird
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA
| | - David A Holowka
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA
| | - Tamas Balla
- Section on Molecular Signal Transduction, Program for Developmental Neuroscience, Eunice Kennedy Shriver NICHD, National Institutes of Health, Bethesda, MD 20892, USA
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39
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Stathopulos PB, Ikura M. Store operated calcium entry: From concept to structural mechanisms. Cell Calcium 2017; 63:3-7. [DOI: 10.1016/j.ceca.2016.11.005] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Revised: 11/24/2016] [Accepted: 11/24/2016] [Indexed: 11/16/2022]
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40
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Fahrner M, Schindl R, Muik M, Derler I, Romanin C. The STIM-Orai Pathway: The Interactions Between STIM and Orai. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 993:59-81. [PMID: 28900909 DOI: 10.1007/978-3-319-57732-6_4] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
A primary Ca2+ entry pathway in non-excitable cells is established by the Ca2+ release-activated Ca2+ channels. Their two limiting molecular components include the Ca2+-sensor protein STIM1 located in the endoplasmic reticulum and the Orai channel in the plasma membrane. STIM1 senses the luminal Ca2+ content, and store depletion induces its oligomerization into puncta-like structures, thereby triggering coupling to as well as activation of Orai channels. A C-terminal STIM1 domain is assumed to couple to both C- and N-terminal, cytosolic strands of Orai, accomplishing gating of the channel. Here we highlight the inter- and intramolecular steps of the STIM1-Orai signaling cascade together with critical sites of the pore structure that accomplishes Ca2+ permeation.
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Affiliation(s)
- Marc Fahrner
- Institute of Biophysics, Johannes Kepler University Linz, 4020, Linz, Austria.
| | - Rainer Schindl
- Institute of Biophysics, Johannes Kepler University Linz, 4020, Linz, Austria
| | - Martin Muik
- Institute of Biophysics, Johannes Kepler University Linz, 4020, Linz, Austria
| | - Isabella Derler
- Institute of Biophysics, Johannes Kepler University Linz, 4020, Linz, Austria
| | - Christoph Romanin
- Institute of Biophysics, Johannes Kepler University Linz, 4020, Linz, Austria.
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41
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Immunological Disorders: Regulation of Ca 2+ Signaling in T Lymphocytes. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 993:397-424. [PMID: 28900926 DOI: 10.1007/978-3-319-57732-6_21] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Engagement of T cell receptors (TCRs) with cognate antigens triggers cascades of signaling pathways in helper T cells. TCR signaling is essential for the effector function of helper T cells including proliferation, differentiation, and cytokine production. It also modulates effector T cell fate by inducing cell death, anergy (nonresponsiveness), exhaustion, and generation of regulatory T cells. One of the main axes of TCR signaling is the Ca2+-calcineurin-nuclear factor of activated T cells (NFAT) signaling pathway. Stimulation of TCRs triggers depletion of intracellular Ca2+ store and, in turn, activates store-operated Ca2+ entry (SOCE) to raise the intracellular Ca2+ concentration. SOCE in T cells is mediated by the Ca2+ release-activated Ca2+ (CRAC) channels, which have been very well characterized in terms of their electrophysiological properties. Identification of STIM1 as a sensor to detect depletion of the endoplasmic reticulum (ER) Ca2+ store and Orai1 as the pore subunit of CRAC channels has dramatically advanced our understanding of the regulatory mechanism of Ca2+ signaling in T cells. In this review, we discuss our current understanding of Ca2+ signaling in T cells with specific focus on the mechanism of CRAC channel activation and regulation via protein interactions. In addition, we will discuss the role of CRAC channels in effector T cells, based on the analyses of genetically modified animal models.
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42
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SOCE proteins, STIM1 and Orai1, are localized to the cleavage furrow during cytokinesis of the first and second cell division cycles in zebrafish embryos. ZYGOTE 2016; 24:880-889. [PMID: 27702423 DOI: 10.1017/s0967199416000216] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
In zebrafish embryos, distinct Ca2+ transients are localized to the early cleavage furrows during the first few cell division cycles. These transients are generated mainly by release via IP3Rs in the endoplasmic reticulum, and they are necessary for furrow positioning, propagation, deepening and apposition. We previously showed, via the use of inhibitors, that store-operated Ca2+ entry (SOCE) also appears to be essential for maintaining the IP3R-mediated elevated levels of [Ca2+]i for the extended periods required for the completion of successful furrow deepening and daughter cell apposition in these large embryonic cells. Here, newly fertilized, dechorionated embryos were fixed at various times during the first and second cell division cycles and immunolabelled with antibodies to STIM1 and/or Orai1 (key components of SOCE). We show that both of these proteins have a dynamic pattern of localization during cytokinesis of the first two cell division cycles. These new data help to support our previous inhibitor results, and provide additional evidence that SOCE contributes to the maintenance of the sustained elevated Ca2+ that is required for the successful completion of cytokinesis in the large cells of embryonic zebrafish.
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43
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Hartzell CA, Jankowska KI, Burkhardt JK, Lewis RS. Calcium influx through CRAC channels controls actin organization and dynamics at the immune synapse. eLife 2016; 5. [PMID: 27440222 PMCID: PMC4956410 DOI: 10.7554/elife.14850] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2016] [Accepted: 06/13/2016] [Indexed: 11/21/2022] Open
Abstract
T cell receptor (TCR) engagement opens Ca2+ release-activated Ca2+ (CRAC) channels and triggers formation of an immune synapse between T cells and antigen-presenting cells. At the synapse, actin reorganizes into a concentric lamellipod and lamella with retrograde actin flow that helps regulate the intensity and duration of TCR signaling. We find that Ca2+ influx is required to drive actin organization and dynamics at the synapse. Calcium acts by promoting actin depolymerization and localizing actin polymerization and the actin nucleation promotion factor WAVE2 to the periphery of the lamellipod while suppressing polymerization elsewhere. Ca2+-dependent retrograde actin flow corrals ER tubule extensions and STIM1/Orai1 complexes to the synapse center, creating a self-organizing process for CRAC channel localization. Our results demonstrate a new role for Ca2+ as a critical regulator of actin organization and dynamics at the synapse, and reveal potential feedback loops through which Ca2+ influx may modulate TCR signaling. DOI:http://dx.doi.org/10.7554/eLife.14850.001 An effective immune response requires the immune system to rapidly recognize and respond to foreign invaders. Immune cells known as T cells recognize infection through a protein on their surface known as the T cell receptor. The T cell receptor binds to foreign proteins displayed on the surface of other cells. This interaction initiates a chain of events, including the opening of calcium channels embedded in the T cell membrane known as CRAC channels, which allows calcium ions to flow into the cell. These events ultimately lead to the activation of the T cell, enabling it to mount an immune response against the foreign invader. As part of the activation process, the T cell spreads over the surface of the cell that is displaying foreign proteins to form an extensive interface known as an immune synapse. The movement of the T cell's internal skeleton (the cytoskeleton) is crucial for the formation and function of the synapse. Actin filaments, a key component of the cytoskeleton, flow from the edge of the synapse toward the center; these rearrangements of the actin cytoskeleton help to transport clusters of T cell receptors to the center of the synapse and enable the T cell receptors to transmit signals that lead to the T cell being activated. It is not entirely clear how the binding of T cell receptors to foreign proteins drives the actin rearrangements, but there is indirect evidence suggesting that calcium ions may be involved. Hartzell et al. have now investigated the interactions between calcium and the actin cytoskeleton at the immune synapse in human T cells. T cells were placed on glass so that they formed immune synapse-like connections with the surface, and actin movements at the synapse were visualized using a specialized type of fluorescence microscopy. When calcium ions were prevented from entering the T cell, the movement of actin stopped almost entirely. Thus, the flow of calcium ions into the T cell through CRAC channels is essential for driving the actin movements that underlie immune synapse development and T cell activation. In further experiments, Hartzell et al. tracked the movements of CRAC channels and actin at the synapse and found that actin filaments create a constricting “corral” that concentrates CRAC channels in the center of the synapse. Thus, by driving cytoskeleton movement, calcium ions also help to organize calcium channels at the immune synapse. Future work will focus on identifying the actin remodeling proteins that enable calcium ions to control this process. DOI:http://dx.doi.org/10.7554/eLife.14850.002
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Affiliation(s)
- Catherine A Hartzell
- Immunology Program, Stanford University, Stanford, United States.,Department of Molecular and Cellular Physiology, Stanford University, Stanford, United States
| | - Katarzyna I Jankowska
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia Research Institute, Philadelphia, United States.,Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, United States
| | - Janis K Burkhardt
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia Research Institute, Philadelphia, United States.,Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, United States
| | - Richard S Lewis
- Immunology Program, Stanford University, Stanford, United States.,Department of Molecular and Cellular Physiology, Stanford University, Stanford, United States
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44
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Guedj C, Abraham N, Jullié D, Randriamampita C. T cell adhesion triggers an early signaling pole distal to the immune synapse. J Cell Sci 2016; 129:2526-37. [PMID: 27185862 DOI: 10.1242/jcs.182311] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Accepted: 05/09/2016] [Indexed: 01/09/2023] Open
Abstract
The immunological synapse forms at the interface between a T cell and an antigen-presenting cell after foreign antigen recognition. The immunological synapse is considered to be the site where the signaling cascade leading to T lymphocyte activation is triggered. Here, we show that another signaling region can be detected before formation of the synapse at the opposite pole of the T cell. This structure appears during the first minute after the contact forms, is transient and contains all the classic components that have been previously described at the immunological synapse. Its formation is independent of antigen recognition but is driven by adhesion itself. It constitutes a reservoir of signaling molecules that are potentially ready to be sent to the immunological synapse through a microtubule-dependent pathway. The antisynapse can thus be considered as a pre-synapse that is triggered independently of antigen recognition.
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Affiliation(s)
- Chloé Guedj
- INSERM, U1016, Institut Cochin, Infection, Immunity and Inflammation Department, 22 rue Méćhain, Paris 75014, France CNRS, UMR8104, Paris 75014, France Université Paris Descartes, Sorbonne Paris Cité, Paris 75014, France
| | - Nicolas Abraham
- INSERM, U1016, Institut Cochin, Infection, Immunity and Inflammation Department, 22 rue Méćhain, Paris 75014, France CNRS, UMR8104, Paris 75014, France Université Paris Descartes, Sorbonne Paris Cité, Paris 75014, France
| | - Damien Jullié
- INSERM, U1016, Institut Cochin, Infection, Immunity and Inflammation Department, 22 rue Méćhain, Paris 75014, France CNRS, UMR8104, Paris 75014, France Université Paris Descartes, Sorbonne Paris Cité, Paris 75014, France
| | - Clotilde Randriamampita
- INSERM, U1016, Institut Cochin, Infection, Immunity and Inflammation Department, 22 rue Méćhain, Paris 75014, France CNRS, UMR8104, Paris 75014, France Université Paris Descartes, Sorbonne Paris Cité, Paris 75014, France
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Srikanth S, Kim KD, Gao Y, Woo JS, Ghosh S, Calmettes G, Paz A, Abramson J, Jiang M, Gwack Y. A large Rab GTPase encoded by CRACR2A is a component of subsynaptic vesicles that transmit T cell activation signals. Sci Signal 2016; 9:ra31. [PMID: 27016526 DOI: 10.1126/scisignal.aac9171] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
More than 60 members of the Rab family of guanosine triphosphatases (GTPases) exist in the human genome. Rab GTPases are small proteins that are primarily involved in the formation, trafficking, and fusion of vesicles. We showed thatCRACR2A(Ca(2+) release-activated Ca(2+) channel regulator 2A) encodes a lymphocyte-specific large Rab GTPase that contains multiple functional domains, including EF-hand motifs, a proline-rich domain (PRD), and a Rab GTPase domain with an unconventional prenylation site. Through experiments involving gene silencing in cells and knockout mice, we demonstrated a role for CRACR2A in the activation of the Ca(2+) and c-Jun N-terminal kinase signaling pathways in response to T cell receptor (TCR) stimulation. Vesicles containing this Rab GTPase translocated from near the Golgi to the immunological synapse formed between a T cell and a cognate antigen-presenting cell to activate these signaling pathways. The interaction between the PRD of CRACR2A and the guanidine nucleotide exchange factor Vav1 was required for the accumulation of these vesicles at the immunological synapse. Furthermore, we demonstrated that GTP binding and prenylation of CRACR2A were associated with its localization near the Golgi and its stability. Our findings reveal a previously uncharacterized function of a large Rab GTPase and vesicles near the Golgi in TCR signaling. Other GTPases with similar domain architectures may have similar functions in T cells.
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Affiliation(s)
- Sonal Srikanth
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles (UCLA), Los Angeles, CA 90095, USA.
| | - Kyun-Do Kim
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles (UCLA), Los Angeles, CA 90095, USA
| | - Yuanyuan Gao
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles (UCLA), Los Angeles, CA 90095, USA
| | - Jin Seok Woo
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles (UCLA), Los Angeles, CA 90095, USA
| | - Shubhamoy Ghosh
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles (UCLA), Los Angeles, CA 90095, USA
| | - Guillaume Calmettes
- Department of Medicine (Cardiology), David Geffen School of Medicine, UCLA, Los Angeles, CA 90095, USA
| | - Aviv Paz
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles (UCLA), Los Angeles, CA 90095, USA
| | - Jeff Abramson
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles (UCLA), Los Angeles, CA 90095, USA
| | - Meisheng Jiang
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, UCLA, Los Angeles, CA 90095, USA
| | - Yousang Gwack
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles (UCLA), Los Angeles, CA 90095, USA.
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Junctophilin-4, a component of the endoplasmic reticulum-plasma membrane junctions, regulates Ca2+ dynamics in T cells. Proc Natl Acad Sci U S A 2016; 113:2762-7. [PMID: 26929330 DOI: 10.1073/pnas.1524229113] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Orai1 and stromal interaction molecule 1 (STIM1) mediate store-operated Ca(2+) entry (SOCE) in immune cells. STIM1, an endoplasmic reticulum (ER) Ca(2+) sensor, detects store depletion and interacts with plasma membrane (PM)-resident Orai1 channels at the ER-PM junctions. However, the molecular composition of these junctions in T cells remains poorly understood. Here, we show that junctophilin-4 (JP4), a member of junctional proteins in excitable cells, is expressed in T cells and localized at the ER-PM junctions to regulate Ca(2+) signaling. Silencing or genetic manipulation of JP4 decreased ER Ca(2+) content and SOCE in T cells, impaired activation of the nuclear factor of activated T cells (NFAT) and extracellular signaling-related kinase (ERK) signaling pathways, and diminished expression of activation markers and cytokines. Mechanistically, JP4 directly interacted with STIM1 via its cytoplasmic domain and facilitated its recruitment into the junctions. Accordingly, expression of this cytoplasmic fragment of JP4 inhibited SOCE. Furthermore, JP4 also formed a complex with junctate, a Ca(2+)-sensing ER-resident protein, previously shown to mediate STIM1 recruitment into the junctions. We propose that the junctate-JP4 complex located at the junctions cooperatively interacts with STIM1 to maintain ER Ca(2+) homeostasis and mediate SOCE in T cells.
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Korzeniowski MK, Baird B, Holowka D. STIM1 activation is regulated by a 14 amino acid sequence adjacent to the CRAC activation domain. AIMS BIOPHYSICS 2016; 3:99-118. [PMID: 27239559 PMCID: PMC4883682 DOI: 10.3934/biophy.2016.1.99] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022] Open
Abstract
Oligomerization of the Ca2+ sensor, STIM1, in the endoplasmic reticulum (ER) membrane, caused by depletion of ER Ca2+ stores, results in STIM1 coupling to the plasma membrane Ca2+ channel protein, Orai1, to activate Ca2+ influx in a process known as store-operated Ca2+ entry. We use fluorimetry-based fluorescence resonance energy transfer (FRET) to monitor changes in STIM1 oligomerization in COS7 cells transfected with STIM1 constructs containing selected truncations, deletions, and point mutations, and labeled with donor and acceptor fluorescent proteins at either the luminal (N-terminal) or the cytoplasmic (C-terminal) ends. Our results with sequential truncations of STIM1 from the C-terminus support previous evidence that the CRAC activation domain (CAD/SOAR, human sequence 342–448) is an oligomer-promoting segment of STIM1, and they show that truncation just after CAD/SOAR (1–448) causes significantly elevated basal cytoplasmic Ca2+ and spontaneous STIM1 clustering. We find that a 14 amino acid sequence just C-terminal of CAD/SOAR (449–462) prevents spontaneous clustering and activation of STIM1 in COS7 cells. In response to store depletion, C-terminally labeled STIM1 without CAD/SOAR clusters together with CAD/SOAR-containing STIM1 constructs. However, these donor-acceptor pairs do not undergo a stimulated increase in FRET, exhibiting instead a decrease in FRET consistent with a stimulated conformational extension in full length STIM1. We find that the 14 amino acid sequence plays a regulatory role in this process. Overall, our FRET results provide evidence in live cells that Ca2+ store depletion stimulates a conformational extension in the cytoplasmic segment of STIM1 that accompanies its oligomerization.
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Affiliation(s)
- Marek K Korzeniowski
- Department of Chemistry and Chemical Biology Cornell University, Ithaca, NY 14853
| | - Barbara Baird
- Department of Chemistry and Chemical Biology Cornell University, Ithaca, NY 14853
| | - David Holowka
- Department of Chemistry and Chemical Biology Cornell University, Ithaca, NY 14853
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48
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Abstract
Ca2+ entry into the cell via store-operated Ca2+ release-activated Ca2+ (CRAC) channels triggers diverse signaling cascades that affect cellular processes like cell growth, gene regulation, secretion, and cell death. These store-operated Ca2+ channels open after depletion of intracellular Ca2+ stores, and their main features are fully reconstituted by the two molecular key players: the stromal interaction molecule (STIM) and Orai. STIM represents an endoplasmic reticulum-located Ca2+ sensor, while Orai forms a highly Ca2+-selective ion channel in the plasma membrane. Functional as well as mutagenesis studies together with structural insights about STIM and Orai proteins provide a molecular picture of the interplay of these two key players in the CRAC signaling cascade. This review focuses on the main experimental advances in the understanding of the STIM1-Orai choreography, thereby establishing a portrait of key mechanistic steps in the CRAC channel signaling cascade. The focus is on the activation of the STIM proteins, the subsequent coupling of STIM1 to Orai1, and the consequent structural rearrangements that gate the Orai channels into the open state to allow Ca2+ permeation into the cell.
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Affiliation(s)
- Isabella Derler
- Institute of Biophysics, Johannes Kepler University of Linz, Linz, Austria; and
| | - Isaac Jardin
- Department of Physiology, University of Extremadura, Cáceres, Spain
| | - Christoph Romanin
- Institute of Biophysics, Johannes Kepler University of Linz, Linz, Austria; and
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49
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Derler I, Jardin I, Stathopulos PB, Muik M, Fahrner M, Zayats V, Pandey SK, Poteser M, Lackner B, Absolonova M, Schindl R, Groschner K, Ettrich R, Ikura M, Romanin C. Cholesterol modulates Orai1 channel function. Sci Signal 2016; 9:ra10. [PMID: 26814231 DOI: 10.1126/scisignal.aad7808] [Citation(s) in RCA: 69] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
STIM1 (stromal interaction molecule 1) and Orai proteins are the essential components of Ca(2+) release-activated Ca(2+) (CRAC) channels. We focused on the role of cholesterol in the regulation of STIM1-mediated Orai1 currents. Chemically induced cholesterol depletion enhanced store-operated Ca(2+) entry (SOCE) and Orai1 currents. Furthermore, cholesterol depletion in mucosal-type mast cells augmented endogenous CRAC currents, which were associated with increased degranulation, a process that requires calcium influx. Single point mutations in the Orai1 amino terminus that would be expected to abolish cholesterol binding enhanced SOCE to a similar extent as did cholesterol depletion. The increase in Orai1 activity in cells expressing these cholesterol-binding-deficient mutants occurred without affecting the amount in the plasma membrane or the coupling of STIM1 to Orai1. We detected cholesterol binding to an Orai1 amino-terminal fragment in vitro and to full-length Orai1 in cells. Thus, our data showed that Orai1 senses the amount of cholesterol in the plasma membrane and that the interaction of Orai1 with cholesterol inhibits its activity, thereby limiting SOCE.
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Affiliation(s)
- Isabella Derler
- Institute of Biophysics, Johannes Kepler University of Linz, Gruberstrasse 40, 4020 Linz, Austria.
| | - Isaac Jardin
- Institute of Biophysics, Johannes Kepler University of Linz, Gruberstrasse 40, 4020 Linz, Austria
| | - Peter B Stathopulos
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Martin Muik
- Institute of Biophysics, Johannes Kepler University of Linz, Gruberstrasse 40, 4020 Linz, Austria
| | - Marc Fahrner
- Institute of Biophysics, Johannes Kepler University of Linz, Gruberstrasse 40, 4020 Linz, Austria
| | - Vasilina Zayats
- Center for Nanobiology and Structural Biology, Institute of Microbiology, Academy of Sciences of the Czech Republic, CZ-373 33 Nové Hrady, Czech Republic
| | - Saurabh K Pandey
- Center for Nanobiology and Structural Biology, Institute of Microbiology, Academy of Sciences of the Czech Republic, CZ-373 33 Nové Hrady, Czech Republic
| | - Michael Poteser
- Institute of Biophysics, Medical University of Graz, Harrachgasse 21/4, 8010 Graz, Austria
| | - Barbara Lackner
- Institute of Biophysics, Johannes Kepler University of Linz, Gruberstrasse 40, 4020 Linz, Austria
| | - Marketa Absolonova
- Institute of Biophysics, Johannes Kepler University of Linz, Gruberstrasse 40, 4020 Linz, Austria
| | - Rainer Schindl
- Institute of Biophysics, Johannes Kepler University of Linz, Gruberstrasse 40, 4020 Linz, Austria
| | - Klaus Groschner
- Institute of Biophysics, Medical University of Graz, Harrachgasse 21/4, 8010 Graz, Austria
| | - Rüdiger Ettrich
- Center for Nanobiology and Structural Biology, Institute of Microbiology, Academy of Sciences of the Czech Republic, CZ-373 33 Nové Hrady, Czech Republic
| | - Mitsu Ikura
- Princess Margaret Cancer Centre and Department of Medical Biophysics, University of Toronto, Toronto, Ontario M5G 1L7, Canada
| | - Christoph Romanin
- Institute of Biophysics, Johannes Kepler University of Linz, Gruberstrasse 40, 4020 Linz, Austria.
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50
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Abstract
Store-operated calcium channels (SOCs) are a major pathway for calcium signaling in virtually all metozoan cells and serve a wide variety of functions ranging from gene expression, motility, and secretion to tissue and organ development and the immune response. SOCs are activated by the depletion of Ca(2+) from the endoplasmic reticulum (ER), triggered physiologically through stimulation of a diverse set of surface receptors. Over 15 years after the first characterization of SOCs through electrophysiology, the identification of the STIM proteins as ER Ca(2+) sensors and the Orai proteins as store-operated channels has enabled rapid progress in understanding the unique mechanism of store-operate calcium entry (SOCE). Depletion of Ca(2+) from the ER causes STIM to accumulate at ER-plasma membrane (PM) junctions where it traps and activates Orai channels diffusing in the closely apposed PM. Mutagenesis studies combined with recent structural insights about STIM and Orai proteins are now beginning to reveal the molecular underpinnings of these choreographic events. This review describes the major experimental advances underlying our current understanding of how ER Ca(2+) depletion is coupled to the activation of SOCs. Particular emphasis is placed on the molecular mechanisms of STIM and Orai activation, Orai channel properties, modulation of STIM and Orai function, pharmacological inhibitors of SOCE, and the functions of STIM and Orai in physiology and disease.
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Affiliation(s)
- Murali Prakriya
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois; and Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, California
| | - Richard S Lewis
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois; and Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, California
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