1
|
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.
Collapse
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
| |
Collapse
|
2
|
Abstract
Nuclear factor of activated T cells (NFAT) was first described almost three decades ago as a Ca
2+/calcineurin-regulated transcription factor in T cells. Since then, a large body of research uncovered the regulation and physiological function of different NFAT homologues in the immune system and many other tissues. In this review, we will discuss novel roles of NFAT in T cells, focusing mainly on its function in humoral immune responses, immunological tolerance, and the regulation of immune metabolism.
Collapse
Affiliation(s)
- Martin Vaeth
- Department of Pathology, New York University School of Medicine, New York, NY, 10016, USA
| | - Stefan Feske
- Department of Pathology, New York University School of Medicine, New York, NY, 10016, USA
| |
Collapse
|
3
|
Courjaret R, Machaca K. Xenopus Oocyte As a Model System to Study Store-Operated Ca(2+) Entry (SOCE). Front Cell Dev Biol 2016; 4:66. [PMID: 27446917 PMCID: PMC4919926 DOI: 10.3389/fcell.2016.00066] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Accepted: 06/09/2016] [Indexed: 11/16/2022] Open
Abstract
Store-operated Ca2+ entry (SOCE) is a ubiquitous Ca2+ influx pathway at the cell membrane that is regulated by Ca2+ content in intracellular stores. SOCE is important for a multitude of physiological processes, including muscle development, T-cell activation, and fertilization. Therefore, understanding the molecular regulation of SOCE is imperative. SOCE activation requires conformational and spatial changes in proteins located in both the endoplasmic reticulum and plasma membrane. This leads to the generation of an ionic current of very small amplitude. Both biochemical and electrophysiological parameters of SOCE can be difficult to record in small mammalian cells. In this protocol we present the different methodologies that enable the study of SOCE in a unique model system, the frog oocyte, which provides several advantages and have contributed significantly to our understanding of SOCE regulation.
Collapse
Affiliation(s)
- Raphaël Courjaret
- Department of Physiology and Biophysics, Weill Cornell Medicine Qatar, Education City, Qatar Foundation Doha, Qatar
| | - Khaled Machaca
- Department of Physiology and Biophysics, Weill Cornell Medicine Qatar, Education City, Qatar Foundation Doha, Qatar
| |
Collapse
|
4
|
Lauffer L, Glas E, Gudermann T, Breit A. Endogenous 5-HT2C Receptors Phosphorylate the cAMP Response Element Binding Protein via Protein Kinase C-Promoted Activation of Extracellular-Regulated Kinases-1/2 in Hypothalamic mHypoA-2/10 Cells. J Pharmacol Exp Ther 2016; 358:39-49. [PMID: 27189964 DOI: 10.1124/jpet.116.232397] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Accepted: 04/25/2016] [Indexed: 02/01/2023] Open
Abstract
Serotonin 5-HT2C receptors (5-HT2CR) activate Gq proteins and are expressed in the central nervous system (CNS). 5-HT2CR regulate emotion, feeding, reward, or cognition and may serve as promising drug targets to treat psychiatric disorders or obesity. Owing to technical difficulties in isolating cells from the CNS and the lack of suitable cell lines endogenously expressing 5-HT2CR, our knowledge about this receptor subtype in native environments is rather limited. The hypothalamic mHypoA-2/10 cell line was recently established and resembles appetite-regulating hypothalamic neurons of the paraventricular nucleus (PVN), where 5-HT2CR have been detected in vivo. Therefore, we tested mHypoA-2/10 cells for endogenous 5-HT2CR expression. Serotonin or the 5-HT2CR preferential agonist WAY-161,503 initiated cAMP response element (CRE)-dependent gene transcription with EC50 values of 15.5 ± 9.8 and 1.1 ± 0.9 nM, respectively. Both responses were blocked by two unrelated 5-HT2CR-selective antagonists (SB-242,084, RS-102,221) but not by a 5-HT2AR (EMD-281,014) or 5-HT2BR (RS-127,455) antagonists. By single-cell calcium imaging, we found that serotonin and WAY-161,503 induced robust calcium transients, which were also blunted by both 5-HT2CR antagonists. Additionally we revealed, first, that 5-HT2CR induced CRE activation via protein kinase C (PKC)-mediated engagement of extracellular-regulated kinases-1/2 and, second, that intrinsic activity of WAY-161,503 was in the range of 0.3-0.5 compared with serotonin, defining the frequently used 5-HT2CR agonist as a partial agonist of endogenous 5-HT2CR. In conclusion, we have shown that hypothalamic mHypoA-2/10 cells endogenously express 5-HT2CR and thus are the first cell line in which to analyze 5-HT2CR pharmacology, signaling, and regulation in its natural environment.
Collapse
Affiliation(s)
- Lisa Lauffer
- Walther-Straub-Institut für Pharmakologie und Toxikologie, Ludwig-Maximilians-Universität München, München, Germany
| | - Evi Glas
- Walther-Straub-Institut für Pharmakologie und Toxikologie, Ludwig-Maximilians-Universität München, München, Germany
| | - Thomas Gudermann
- Walther-Straub-Institut für Pharmakologie und Toxikologie, Ludwig-Maximilians-Universität München, München, Germany
| | - Andreas Breit
- Walther-Straub-Institut für Pharmakologie und Toxikologie, Ludwig-Maximilians-Universität München, München, Germany
| |
Collapse
|
5
|
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.
Collapse
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
| |
Collapse
|
6
|
Qin JJ, Nag S, Wang W, Zhou J, Zhang WD, Wang H, Zhang R. NFAT as cancer target: mission possible? Biochim Biophys Acta Rev Cancer 2014; 1846:297-311. [PMID: 25072963 DOI: 10.1016/j.bbcan.2014.07.009] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Revised: 07/17/2014] [Accepted: 07/22/2014] [Indexed: 12/30/2022]
Abstract
The NFAT signaling pathway regulates various aspects of cellular functions; NFAT acts as a calcium sensor, integrating calcium signaling with other pathways involved in development and growth, immune response, and inflammatory response. The NFAT family of transcription factors regulates diverse cellular functions such as cell survival, proliferation, migration, invasion, and angiogenesis. The NFAT isoforms are constitutively activated and overexpressed in several cancer types wherein they transactivate downstream targets that play important roles in cancer development and progression. Though the NFAT family has been conclusively proved to be pivotal in cancer progression, the different isoforms play distinct roles in different cellular contexts. In this review, our discussion is focused on the mechanisms that drive the activation of various NFAT isoforms in cancer. Additionally, we analyze the potential of NFAT as a valid target for cancer prevention and therapy.
Collapse
Affiliation(s)
- Jiang-Jiang Qin
- Department of Pharmaceutical Sciences, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, TX 79106, USA
| | - Subhasree Nag
- Department of Pharmaceutical Sciences, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, TX 79106, USA
| | - Wei Wang
- Department of Pharmaceutical Sciences, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, TX 79106, USA; Cancer Biology Center, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, TX 79106, USA
| | - Jianwei Zhou
- Department of Molecular Cell Biology and Toxicology, Cancer Center, School of Public Health, Nanjing Medical University, Nanjing, Jiangsu 210029, PR China
| | - Wei-Dong Zhang
- School of Pharmacy, Shanghai Jiao Tong University, Shanghai 200240, PR China
| | - Hui Wang
- Key Laboratory of Food Safety Research, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, PR China; Key Laboratory of Food Safety Risk Assessment, Ministry of Health, Beijing 100021, PR China
| | - Ruiwen Zhang
- Department of Pharmaceutical Sciences, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, TX 79106, USA; Cancer Biology Center, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, TX 79106, USA.
| |
Collapse
|
7
|
Zhao L, Sullivan MN, Chase M, Gonzales AL, Earley S. Calcineurin/nuclear factor of activated T cells-coupled vanilliod transient receptor potential channel 4 ca2+ sparklets stimulate airway smooth muscle cell proliferation. Am J Respir Cell Mol Biol 2014; 50:1064-75. [PMID: 24392954 PMCID: PMC4068915 DOI: 10.1165/rcmb.2013-0416oc] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2013] [Accepted: 12/16/2013] [Indexed: 11/24/2022] Open
Abstract
Proliferation of airway smooth muscle cells (ASMCs) contributes to the remodeling and irreversible obstruction of airways during severe asthma, but the mechanisms underlying this disease process are poorly understood. Here we tested the hypothesis that Ca(2+) influx through the vanilliod transient receptor potential channel (TRPV) 4 stimulates ASMC proliferation. We found that synthetic and endogenous TRPV4 agonists increase proliferation of primary ASMCs. Furthermore, we demonstrate that Ca(2+) influx through individual TRPV4 channels produces Ca(2+) microdomains in ASMCs, called "TRPV4 Ca(2+) sparklets." We also show that TRPV4 channels colocalize with the Ca(2+)/calmodulin-dependent protein phosphatase calcineurin in ASMCs. Activated calcineurin dephosphorylates nuclear factor of activated T cells (NFAT) transcription factors cytosolic (c) to allow nuclear translocation and activation of synthetic transcriptional pathways. We show that ASMC proliferation in response to TRPV4 activity is associated with calcineurin-dependent nuclear translocation of the NFATc3 isoform tagged with green florescent protein. Our findings suggest that Ca(2+) microdomains created by TRPV4 Ca(2+) sparklets activate calcineurin to stimulate nuclear translocation of NFAT and ASMC proliferation. These findings further suggest that inhibition of TRPV4 could diminish asthma-induced airway remodeling.
Collapse
Affiliation(s)
- Limin Zhao
- Vascular Physiology Research Group, Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado
- Henan Provincial People's Hospital of Zhengzhou University, Zhengzhou, Henan, China
| | - Michelle N. Sullivan
- Vascular Physiology Research Group, Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado
| | - Marlee Chase
- Vascular Physiology Research Group, Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado
| | - Albert L. Gonzales
- Department of Pharmacology, University of Vermont School of Medicine, Burlington, Vermont; and
| | - Scott Earley
- Department of Pharmacology, University of Nevada School of Medicine, Reno, Nevada
| |
Collapse
|
8
|
Chen QQ, Zhang W, Chen XF, Bao YJ, Wang J, Zhu WZ. Electrical field stimulation induces cardiac fibroblast proliferation through the calcineurin-NFAT pathway. Can J Physiol Pharmacol 2012; 90:1611-22. [PMID: 23210440 DOI: 10.1139/y2012-133] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Most cardiac diseases are associated with fibrosis. Calcineurin (CaN) is regulated by Ca(2+)/calmodulin (CaM). The CaN-NFAT (nuclear factor of activated T cell) pathway is involved in the process of cardiac diseases, such as cardiac hypertrophy, but its effect on myocardial fibrosis remains unclear. The present study investigates whether the CaN-NFAT pathway is involved in cardiac fibroblast (CF) proliferation induced by electrical field stimulation (EFS), which recently became a popular treatment for heart failure and cardiac tissue engineering. CF proliferation was evaluated by a cell survival assay (MTT) and cell counts. Myocardial fibrosis was assessed by collagen I and collagen III protein expression. Green fluorescent protein (GFP)-tagged NFAT was used to detect NFAT nuclear translocation. CF proliferation, myocardial fibrosis, CaN activity, and NFAT nuclear translocation were enhanced by EFS. More importantly, these effects were abolished by CaN inhibitors, dominant negative CaN (DN-CaN), and CaN gene silenced with siRNA. Furthermore, buffering intracellular Ca(2+) with BAPTA-AM and blocking Ca(2+) influx with nifedipine suppressed EFS-induced increase in intracellular Ca(2+) and CF proliferation. These results suggested that the CaN-NFAT pathway mediates CF proliferation, and that the CaN-NFAT pathway might be a possible therapeutic target for EFS-induced myocardial fibrosis and cardiac tissue engineering.
Collapse
Affiliation(s)
- Qing-Qing Chen
- Department of Pharmacology, Nantong University Medical College, Nantong, P.R. China
| | | | | | | | | | | |
Collapse
|
9
|
Arredouani A, Yu F, Sun L, Machaca K. Regulation of store-operated Ca2+ entry during the cell cycle. J Cell Sci 2010; 123:2155-62. [PMID: 20554894 DOI: 10.1242/jcs.069690] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cytoplasmic Ca(2+) signals are central to numerous cell physiological processes, including cellular proliferation. Historically, much of the research effort in this area has focused on the role of Ca(2+) signals in cell-cycle progression. It is becoming clear, however, that the relationship between Ca(2+) signaling and the cell cycle is a 'two-way street'. Specifically, Ca(2+)-signaling pathways are remodeled during M phase, leading to altered Ca(2+) dynamics. Such remodeling probably better serves the large variety of functions that cells must perform during cell division compared with during interphase. This is clearly the case during oocyte meiosis, because remodeling of Ca(2+) signals partially defines the competence of the egg to activate at fertilization. Store-operated Ca(2+) entry (SOCE) is a ubiquitous Ca(2+)-signaling pathway that is regulated during M phase. In this Commentary, we discuss the latest advances in our understanding of how SOCE is regulated during cell division.
Collapse
Affiliation(s)
- Abdelilah Arredouani
- Department of Physiology and Biophysics, Weill Cornell Medical College in Qatar (WCMC-Q), Education City, Qatar Foundation, Doha, Qatar
| | | | | | | |
Collapse
|
10
|
|
11
|
Huang YH, Hoebe K, Sauer K. New therapeutic targets in immune disorders: ItpkB, Orai1 and UNC93B. Expert Opin Ther Targets 2008; 12:391-413. [PMID: 18348677 DOI: 10.1517/14728222.12.4.391] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND Sequencing of the murine and human genomes has enabled large-scale functional genomics approaches to target identification. This holds the promise of drastically accelerating target discovery. Moreover, by providing an initial validation coincident with target identification, cell based cDNA or small interfering RNA (siRNA) screens and in particular genome-wide in vivo approaches, including forward or reverse genetics and analyses of natural gene polymorphisms, can move the relatively late step of target validation to the beginning of the process, reducing the risk of pursuing targets with little in vivo relevance. OBJECTIVE We critically discuss the value of combining functional genomics with traditional approaches for accelerating target identification and validation. METHODS We evaluate the potentials of inositol (1,4,5)trisphosphate 3-kinase B (ItpkB), Orai1 and UNC93B, three particularly interesting proteins that were recently identified through functional genomics, as targets in immune disorders. RESULTS/CONCLUSION Combining functional genomics with traditional approaches can accelerate target discovery and validation, but requires a follow-up platform that integrates and analyzes all relevant data for assessment of the clinical potential of the growing number of novel targets.
Collapse
Affiliation(s)
- Yina H Huang
- The Scripps Research Institute, Department of Immunology, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
| | | | | |
Collapse
|
12
|
Wu H, Peisley A, Graef IA, Crabtree GR. NFAT signaling and the invention of vertebrates. Trends Cell Biol 2007; 17:251-60. [PMID: 17493814 DOI: 10.1016/j.tcb.2007.04.006] [Citation(s) in RCA: 154] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2007] [Revised: 03/27/2007] [Accepted: 04/25/2007] [Indexed: 01/08/2023]
Abstract
The calcium/calcineurin-dependent NFATc family is thought to have arisen following the recombination of an ancient precursor with a Rel domain about 500 million years ago, producing a new group of signaling and transcription factors (the NFATc genes) found only in the genomes of vertebrates. Cell biological, genetic and biochemical evidence indicates that the circuitry of this pathway is well suited for intercalation with older pathways. We propose that this recombination enabled Ca(2+) signals to be redirected to a new transcriptional program, which provided part of the groundwork for vertebrate morphogenesis and organogenesis. This notion predicts that calcineurin-NFAT signaling would be essential for much of vertebrate development. We review recent evidence supporting this prediction and propose a systematic approach to explore aspects of vertebrate morphogenesis.
Collapse
Affiliation(s)
- Hai Wu
- Stanford University and the Howard Hughes Medical Institute, Department of Pathology, Beckman Center, Stanford, CA 94305, USA
| | | | | | | |
Collapse
|
13
|
Huang YH, Barouch-Bentov R, Herman A, Walker J, Sauer K. Integrating traditional and postgenomic approaches to investigate lymphocyte development and function. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2006; 584:245-76. [PMID: 16802612 DOI: 10.1007/0-387-34132-3_18] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/27/2023]
Affiliation(s)
- Yina Hsing Huang
- Genomics Institute of the Novartis Research Foundation, 10675 John J. Hopkins Drive, San Diego, CA 92121, USA
| | | | | | | | | |
Collapse
|
14
|
Acevedo-Suárez CA, Kilkenny DM, Reich MB, Thomas JW. Impaired intracellular calcium mobilization and NFATc1 availability in tolerant anti-insulin B cells. THE JOURNAL OF IMMUNOLOGY 2006; 177:2234-41. [PMID: 16887983 DOI: 10.4049/jimmunol.177.4.2234] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
B lymphocytes that recognize soluble self-Ags are routinely found in normal individuals in a functionally inactive or anergic state. Current models indicate that this tolerant state is maintained by interactions with self-Ags that uncouple the BCR from downstream signaling pathways and increase levels of free calcium. Contrary to this expectation, B cells that harbor anti-insulin Ig transgenes (125Tg) are maintained in a tolerant state even though free calcium levels remain normal and tyrosine kinase substrate phosphorylation is preserved following BCR stimulation. Under basal conditions, intracellular levels of inositol 1,4,5-trisphosphate are increased and NFATc1 levels are reduced in 125Tg B cells. The 125Tg B cells are markedly impaired in their ability to mobilize calcium upon stimulation with ionomycin, and BCR-induced calcium mobilization from internal stores is decreased. In contrast, poisoning intracellular calcium pumps with thapsigargin increases calcium mobilization in 125Tg B cells. Changes in calcium signaling are accompanied by a failure of 125Tg B cells to translocate NFATc1 into the nucleus following stimulation with either anti-IgM or ionomycin. Thus, disassociation of BCR from multiple signaling pathways is not essential for maintaining tolerance in anti-insulin 125Tg B cells. Rather, BCRs that are occupied by autologous insulin deliver signals that induce changes in intracellular calcium mobilization and maintain tolerance by preventing activation of key transcription factors such as NFAT.
Collapse
|
15
|
Morales S, Diez A, Puyet A, Camello PJ, Camello-Almaraz C, Bautista JM, Pozo MJ. Calcium controls smooth muscle TRPC gene transcription via the CaMK/calcineurin-dependent pathways. Am J Physiol Cell Physiol 2006; 292:C553-63. [PMID: 16956967 DOI: 10.1152/ajpcell.00096.2006] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Transient receptor potential protein family C (TRPC) has been proposed as a candidate for channels involved in capacitative Ca(2+) entry (CCE) mechanisms, but the modulation of their gene expression remains unexplored. In this study we show that guinea pig gallbladder smooth muscle contains mRNA encoding TRPC1, TRPC2, TRPC3, and TRPC4 proteins whose abundance depends on cytosolic Ca(2+) level ([Ca(2+)](i)). Thus lowering the levels of cellular calcium with the chelators EGTA and BAPTA AM results in a downregulation of TRPC1-TRPC4 gene and protein expression. In contrast, activation of Ca(2+) influx through L-type Ca(2+) channels and Ca(2+) release from intracellular stores induced an increase in TRPC1-TRPC4 mRNA and protein abundance. Activation of Ca(2+)/calmodulin-dependent kinases (CaMK) and phosphorylation of cAMP-response element binding protein accounts for the increase in TRPC mRNA transcription in response to L-type channel-mediated Ca(2+) influx . In addition to this mechanism, activation of TRPC gene expression by intracellular Ca(2+) release also involves calcineurin pathway. According to the proposed role for these channels, activation of CCE induced an increase in TRPC1 and TRPC3 mRNA abundance, which depends on the integrity of the calcineurin and CaMK pathways. These findings show for the first time an essential autoregulatory role of Ca(2+) in Ca(2+) homeostasis at the level of TRPC gene and protein expression.
Collapse
Affiliation(s)
- Sara Morales
- Department of Physiology, Nursing School, University of Extremadura, Avenida Universidad s/n, 10071 Cáceres, Spain
| | | | | | | | | | | | | |
Collapse
|
16
|
Feske S, Prakriya M, Rao A, Lewis RS. A severe defect in CRAC Ca2+ channel activation and altered K+ channel gating in T cells from immunodeficient patients. ACTA ACUST UNITED AC 2006; 202:651-62. [PMID: 16147976 PMCID: PMC2212870 DOI: 10.1084/jem.20050687] [Citation(s) in RCA: 190] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Engagement of the TCR triggers sustained Ca2+ entry through Ca2+ release-activated Ca2+ (CRAC) channels, which helps drive gene expression underlying the T cell response to pathogens. The identity and activation mechanism of CRAC channels at a molecular level are unknown. We have analyzed ion channel expression and function in T cells from SCID patients which display 1–2% of the normal level of Ca2+ influx and severely impaired T cell activation. The lack of Ca2+ influx is not due to deficient regulation of Ca2+ stores or expression of several genes implicated in controlling Ca2+ entry in lymphocytes (kcna3/Kv1.3, kcnn4/IKCa1, trpc1, trpc3, trpv6, stim1). Instead, electrophysiologic measurements show that the influx defect is due to a nearly complete absence of functional CRAC channels. The lack of CRAC channel activity is correlated with diminished voltage sensitivity and slowed activation kinetics of the voltage-dependent Kv1.3 channel. These results demonstrate that CRAC channels provide the major, if not sole, pathway for Ca2+ entry activated by the TCR in human T cells. They also offer evidence for a functional link between CRAC and Kv1.3 channels, and establish a model system for molecular genetic studies of the CRAC channel.
Collapse
Affiliation(s)
- Stefan Feske
- CBR Institute for Biomedical Research and Department of Pathology, Harvard Medical School, Boston, MA 02115, USA
| | | | | | | |
Collapse
|
17
|
Gallo EM, Canté-Barrett K, Crabtree GR. Lymphocyte calcium signaling from membrane to nucleus. Nat Immunol 2005; 7:25-32. [PMID: 16357855 DOI: 10.1038/ni1295] [Citation(s) in RCA: 151] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2005] [Accepted: 11/14/2005] [Indexed: 12/14/2022]
Abstract
Ca(2+) signals control a variety of lymphocyte responses, ranging from short-term cytoskeletal modifications to long-term changes in gene expression. The identification of molecules and channels that modulate Ca(2+) entry into T and B lymphocytes has both provided details of the molecular events leading to immune responses and raised controversy. Here we review studies of the pathways that allow Ca(2+) entry, the function of Ca(2+) in the regulation of cell polarity and motility and the principles by which Ca(2+)-dependent transcription regulates lymphocyte function.
Collapse
Affiliation(s)
- Elena M Gallo
- Program in Immunology, Stanford University, Stanford, California 94305, USA
| | | | | |
Collapse
|
18
|
Kang S, Li H, Rao A, Hogan PG. Inhibition of the Calcineurin-NFAT Interaction by Small Organic Molecules Reflects Binding at an Allosteric Site. J Biol Chem 2005; 280:37698-706. [PMID: 16148011 DOI: 10.1074/jbc.m502247200] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Transcriptional signaling from the Ca(2+)-calmodulin-activated phosphatase calcineurin to its substrate NFAT (nuclear factor of activated T cells, also termed NFATc) is critically dependent on a protein-protein docking interaction between calcineurin and the PXIXIT motif in NFAT. Several inhibitors of NFAT-calcineurin association (INCA compounds) prevent binding of NFAT or the peptide ligand PVIVIT to calcineurin. Here we show that the binding site on calcineurin for INCA1, INCA2, and INCA6 is centered on cysteine 266 of calcineurin Aalpha and does not coincide with the core PXIXIT-binding site. Although ample evidence indicates that INCA1 and INCA2 react covalently with cysteine 266, covalent derivatization alone is not sufficient for maximal inhibition of the calcineurin-PVIVIT interaction, because the maleimide INCA12 reacts with the same site and produces only very modest inhibition. Thus, inhibition arises through an allosteric change affecting the PXIXIT docking site, which may be assisted by covalent binding but depends on other specific features of the ligand. The spatial arrangement of the binding sites for PVIVIT and INCA makes it probable that the change in conformation involves the beta11-beta12 loop of calcineurin. The finding that an allosteric site controls NFAT binding opens new alternatives for inhibition of calcineurin-NFAT signaling.
Collapse
Affiliation(s)
- Sunghyun Kang
- CBR Institute for Biomedical Research, Boston, MA 02115, USA
| | | | | | | |
Collapse
|
19
|
Tamareille S, Mignen O, Capiod T, Rücker-Martin C, Feuvray D. High glucose-induced apoptosis through store-operated calcium entry and calcineurin in human umbilical vein endothelial cells. Cell Calcium 2005; 39:47-55. [PMID: 16243395 DOI: 10.1016/j.ceca.2005.09.008] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2005] [Revised: 09/05/2005] [Accepted: 09/09/2005] [Indexed: 12/11/2022]
Abstract
Diabetes mellitus causes multiple cardiovascular complications. Previous studies have shown that prolonged exposure (96 h) of human umbilical vein endothelial cells (HUVECs) to hyperglycemia causes a significant increase in apoptosis. We report here that this increase in apoptosis is associated with an increase in Ca(2+) current (whole cell patch-clamp recorded) resulting from Ca(2+) entry mediated by store-operated channels (SOCs). The number of apoptotic cells after prolonged high glucose (HG, 30 mmol/L) exposure was significantly reduced in the presence of the SOC inhibitor 2-APB or of La(3+). A marked increase (approximately 80%) in Ca(2+)-dependent calcineurin (CN-A) phosphatase activity also occurred after prolonged HG exposure. Prolonged HG exposure-induced increase in CN-A activity was prevented by 2-APB, and selective CN-A phosphatase inhibition by FK506 or calmodulin inhibition by calmidazolium decreased HG-induced apoptosis. Blocking hydrogen peroxide production using catalase or inhibiting the tyrosine kinase pp60(src) during prolonged exposure to HG, resulted in a marked decrease in apoptosis and was further associated with a significant reduction in CN-A phosphatase activity. The results demonstrate a significant role for Ca(2+) entry in HG-induced apoptosis in HUVECs, and suggest that this role is mediated via H(2)O(2) generation and the action of the Ca(2+)-activated protein phosphatase calcineurin.
Collapse
Affiliation(s)
- Sophie Tamareille
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche 8078, Université Paris XI, Hôpital Marie Lannelongue, 92350 Le Plessis Robinson, France
| | | | | | | | | |
Collapse
|
20
|
Venkatesh N, Feng Y, DeDecker B, Yacono P, Golan D, Mitchison T, McKeon F. Chemical genetics to identify NFAT inhibitors: potential of targeting calcium mobilization in immunosuppression. Proc Natl Acad Sci U S A 2004; 101:8969-74. [PMID: 15184684 PMCID: PMC428456 DOI: 10.1073/pnas.0402803101] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The development of more selective immunosuppressive agents to mitigate transplant rejection and autoimmune diseases requires effective strategies of blocking signaling pathways in T cells. Current immunosuppressive strategies use cyclosporin A (CsA) or FK506 to inhibit calcineurin, which dephosphorylates and promotes the nuclear import of nuclear factor of activated T cells (NFAT) transcription factors. These nuclear NFATs then transactivate cytokine genes that regulate proliferative responses of T cells. Both CsA and FK506 have debilitating side effects, including nephrotoxicity, hypertension, diabetes, and seizures, that argue for the development of alternative or complementary agents. To this end, we developed cell-based assays for monitoring NFAT dynamics in nonlymphoid cells to identify small molecules that inhibit NFAT nuclear import. Interestingly, we found that the majority of these small molecules suppress NFAT signaling by interfering with "capacitative" or "store-operated" calcium mobilization, thus raising the possibility that such mobilization processes are relevant targets in immunosuppression therapy. Further, these small molecules also show dose-dependent suppression of cytokine gene expression in T cells. Significantly, the IC(50) of CsA in primary T cells was reduced by the addition of suboptimal concentrations of these compounds, suggesting the possibility that such small molecules, in combination with CsA, offer safer means of immunosuppression.
Collapse
|
21
|
Bultynck G, Vermassen E, Szlufcik K, De Smet P, Fissore RA, Callewaert G, Missiaen L, De Smedt H, Parys JB. Calcineurin and intracellular Ca2+-release channels: regulation or association? Biochem Biophys Res Commun 2004; 311:1181-93. [PMID: 14623304 DOI: 10.1016/j.bbrc.2003.08.084] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The Ca(2+)- and calmodulin-dependent phosphatase calcineurin was reported to interact with the inositol 1,4,5-trisphosphate receptor (IP(3)R) and the ryanodine receptor (RyR) and to modulate their phosphorylation status and activity. However, controversial data on the molecular mechanisms involved and on the functional relevance of calcineurin for these channel-complexes have been described. Hence, we will focus on the functional importance of calcineurin for IP(3)R and RyR function and on the different mechanisms by which Ca(2+)-dependent dephosphorylation can affect the gating of those intracellular Ca(2+)-release channels. Since many studies made use of immunosuppressive drugs that are inhibiting calcineurin activity, we will also have to take the different side effects of these drugs into account for the proper interpretation of the effects of calcineurin on intracellular Ca(2+)-release channels. In addition, it became recently known that various other phosphatases and kinases can associate with these channels, thereby forming macromolecular complexes. The relevance of these enzymes for IP(3)R and RyR functioning will be reviewed since in some cases they could interfere with the effects ascribed to calcineurin. Finally, we will discuss the downstream effects of calcineurin on the regulation of the expression levels of intracellular Ca(2+)-release channels as well as the relation between IP(3)R- and RyR-mediated Ca(2+) release and calcineurin-dependent gene expression.
Collapse
Affiliation(s)
- G Bultynck
- Department of Biological Sciences, Stanford University, Gilbert Hall, Room 208B, 371 Serra Mall, Stanford, CA 94305-5020, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
22
|
Abstract
The human immunodeficiency virus type 1 (HIV-1) has evolved to coordinate its replication with the activation state of the host CD4T cell. To this end, it taps into major host cell signaling pathways and their associated transcription factors. Of these, T-cell activation and the transcription factor NF-kappaB, respectively, have become the best-studied examples. The past several years have revealed compelling evidence that another transcription factor family involved in T-cell activation, the nuclear factor of activated T cells (NFAT), plays an important role in the regulation of HIV-1. Major advances have been made in our understanding of the interaction of HIV-1 with this intriguing transcription factor. The duplicated NF-kappaB binding sites in the HIV-1 enhancer surprisingly also bind NFAT proteins and appear to be the most important targets for NFAT transactivation of the HIV-1 long terminal repeat. The crystal structure of NFAT1 bound to one of these duplicated sites was solved recently. Interestingly, it showed that NFAT1 binds to this site as a homodimer and occupies the core of the NF-kappaB site, suggesting mutually exclusive binding and alternate transactivation by these two factors. NFAT also regulates HIV-1 infection indirectly, as it can relieve a block to reverse transcription in quiescent T cells. In turn, HIV-1, and particularly its Tat and Nef gene products, can upregulate NFAT expression and activity. This reciprocal regulation between virus and transcription factor potentially creates a positive feedback loop, which may facilitate the establishment of early HIV-1 infection and, later, the transition from latent to productive infection. The immunosuppressive drug cyclosporin A (CsA) inhibits NFAT activity and thus represents a potential treatment for HIV-1 infection. Recent small-scale clinical trials have yielded optimistic results, suggesting roles for CsA after organ transplantation in HIV-1+ individuals and as adjunct treatment in stable early HIV-1 infection.
Collapse
Affiliation(s)
- F Pessler
- Division of Rheumatology, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | | |
Collapse
|
23
|
Store-operated calcium channels: properties, functions and the search for a molecular mechanism. MOLECULAR INSIGHTS INTO ION CHANNEL BIOLOGY IN HEALTH AND DISEASE 2004. [DOI: 10.1016/s1569-2558(03)32006-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
|
24
|
Mignen O, Thompson JL, Shuttleworth TJ. Calcineurin directs the reciprocal regulation of calcium entry pathways in nonexcitable cells. J Biol Chem 2003; 278:40088-96. [PMID: 12874277 DOI: 10.1074/jbc.m306365200] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The reciprocal regulation of noncapacitative and capacitative (or store-operated) Ca2+ entry in nonexcitable cells (Mignen, O., Thompson, J. L., and Shuttleworth, T. J. (2001) J. Biol. Chem. 276, 35676-35683) represents a switching between two distinct Ca2+-selective channels: the noncapacitative arachidonate-regulated Ca2+ channels (ARC channels) and the store-operated Ca2+ channels (SOC channels). This switch is directly associated with the change from oscillatory to sustained Ca2+ signals as agonist concentrations increase and involves a Ca2+-dependent inhibition of the ARC channels. Here we show that this process is mediated via a calcineurin-dependent inhibition of the noncapacitative ARC channels. Pharmacological and molecular inhibition of calcineurin activity (using cyclosporin or the FK506 analogue ascomycin, and a transfected C-terminal domain of the calcineurin inhibitory protein CAIN, respectively) results in a complete reversal of the Ca2+-dependent inhibition of the ARC channels. Agonist concentrations that result in oscillatory Ca2+ signals and specifically activate Ca2+ entry through the ARC channels fail to increase calcineurin activity. However, agonist concentrations that activate the store-operated Ca2+ channels and produce prolonged increases in cytosolic Ca2+ concentrations increase calcineurin activity. Thus, calcineurin is the key mediator of the reciprocal regulation of these co-existing channels, allowing each to play a unique and non-overlapping role in Ca2+ signaling.
Collapse
Affiliation(s)
- Olivier Mignen
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, New York 14642, USA
| | | | | |
Collapse
|
25
|
Machaca K. Ca2+-calmodulin-dependent protein kinase II potentiates store-operated Ca2+ current. J Biol Chem 2003; 278:33730-7. [PMID: 12821654 PMCID: PMC1282465 DOI: 10.1074/jbc.m305023200] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A rise in intracellular Ca2+ (Ca2+i) mediates various cellular functions ranging from fertilization to gene expression. A ubiquitous Ca2+ influx pathway that contributes significantly to the generation of Ca2+i signals, especially in non-excitable cells, is store-operated Ca2+ entry (SOCE). Consequently, the modulation of SOCE current affects Ca2+i dynamics and thus the ensuing cellular response. Therefore, it is important to define the mechanisms that regulate SOCE. Here we show that a rise in Ca2+i potentiates SOCE. This potentiation is mediated by Ca2+-calmodulin-dependent protein kinase II (CaMKII), because inhibition of endogenous CaMKII activity abrogates Ca2+i-mediated SOCE potentiation and expression of constitutively active CaMKII potentiates SOCE current independently of Ca2+i. Moreover, we present evidence that CaMKII potentiates SOCE by altering SOCE channel gating. The regulation of SOCE by CaMKII defines a novel modulatory mechanism of SOCE with important physiological consequences.
Collapse
Affiliation(s)
- Khaled Machaca
- Department of Physiology & Biophysics, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205, USA.
| |
Collapse
|
26
|
Abstract
The modulation of intracellular calcium ion concentration, [Ca(2+)](i), is a common signalling mechanism used in many biological systems. B and T lymphocytes rely on Ca(2+) signalling to initiate both developmental and activation programs. Recent data has shed new light on the initiation of this signalling pathway, the connection between the release of intracellular Ca(2+) stores and the influx of extracellular Ca(2+), and the molecular identity of the elusive Ca(2+) release-activated Ca(2+) (CRAC) channel. In addition, recent gene profiling of T lymphocytes has identified the genes that are controlled by [Ca(2+)](i) and the Ca(2+)-dependent phosphatase calcineurin.
Collapse
Affiliation(s)
- Monte M Winslow
- Program in Immunology and the Howard Hughes Medical Institute, Stanford University, Stanford CA 94305, USA.
| | | | | |
Collapse
|
27
|
Gomez MF, Stevenson AS, Bonev AD, Hill-Eubanks DC, Nelson MT. Opposing actions of inositol 1,4,5-trisphosphate and ryanodine receptors on nuclear factor of activated T-cells regulation in smooth muscle. J Biol Chem 2002; 277:37756-64. [PMID: 12145283 DOI: 10.1074/jbc.m203596200] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The nuclear factor of activated T-cells (NFAT), originally identified in T-cells, has since been shown to play a role in mediating Ca(2+)-dependent gene transcription in diverse cell types outside of the immune system. We have previously shown that nuclear accumulation of NFATc3 is induced in ileal smooth muscle by platelet-derived growth factor in a manner that depends on Ca(2+) influx through L-type, voltage-dependent Ca(2+) channels. Here we show that NFATc3 is also the predominant NFAT isoform expressed in cerebral artery smooth muscle and is induced to accumulate in the nucleus by UTP and other G(q/11)-coupled receptor agonists. This induction is mediated by calcineurin and is dependent on sarcoplasmic reticulum Ca(2+) release through inositol 1,4,5-trisphosphate receptors and extracellular Ca(2+) influx through L-type, voltage-dependent Ca(2+) channels. Consistent with results obtained in ileal smooth muscle, depolarization-induced Ca(2+) influx fails to induce NFAT nuclear accumulation in cerebral arteries. We also provide evidence that Ca(2+) release by ryanodine receptors in the form of Ca(2+) sparks may exert an inhibitory influence on UTP-induced NFATc3 nuclear accumulation and further suggest that UTP may act, in part, by inhibiting Ca(2+) sparks. These results are consistent with a multifactorial regulation of NFAT nuclear accumulation in smooth muscle that is likely to involve several intracellular signaling pathways, including local effects of sarcoplasmic reticulum Ca(2+) release and effects attributable to global elevations in intracellular Ca(2+).
Collapse
Affiliation(s)
- Maria F Gomez
- Department of Pharmacology, University of Vermont, Burlington, Vermont 05405, USA
| | | | | | | | | |
Collapse
|
28
|
Abstract
Calcium signaling activates the phosphatase calcineurin and induces movement of NFATc proteins into the nucleus, where they cooperate with other proteins to form complexes on DNA. Nuclear import is opposed by kinases such as GSK3, thereby rendering transcription continuously responsive to receptor occupancy. Disruptions of the genes involved in NFAT signaling are implicating this pathway as a regulator of developmental cell-cell interactions.
Collapse
Affiliation(s)
- Gerald R Crabtree
- Department of Developmental Biology, Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA.
| | | |
Collapse
|
29
|
Machaca K, Haun S. Induction of maturation-promoting factor during Xenopus oocyte maturation uncouples Ca(2+) store depletion from store-operated Ca(2+) entry. J Cell Biol 2002; 156:75-85. [PMID: 11781335 PMCID: PMC1307503 DOI: 10.1083/jcb.200110059] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2001] [Revised: 11/15/2001] [Accepted: 11/19/2001] [Indexed: 11/22/2022] Open
Abstract
During oocyte maturation, eggs acquire the ability to generate specialized Ca(2+) signals in response to sperm entry. Such Ca(2+) signals are crucial for egg activation and the initiation of embryonic development. We examined the regulation during Xenopus oocyte maturation of store-operated Ca(2+) entry (SOCE), an important Ca(2+) influx pathway in oocytes and other nonexcitable cells. We have previously shown that SOCE inactivates during Xenopus oocyte meiosis. SOCE inactivation may be important in preventing premature egg activation. In this study, we investigated the correlation between SOCE inactivation and the Mos-mitogen-activated protein kinase (MAPK)-maturation-promoting factor (MPF) kinase cascade, which drives Xenopus oocyte maturation. SOCE inactivation at germinal vesicle breakdown coincides with an increase in the levels of MAPK and MPF. By differentially inducing Mos, MAPK, and MPF, we demonstrate that the activation of MPF is necessary for SOCE inactivation during oocyte maturation. In contrast, sustained high levels of Mos kinase and the MAPK cascade have no effect on SOCE activation. We further show that preactivated SOCE is not inactivated by MPF, suggesting that MPF does not block Ca(2+) influx through SOCE channels, but rather inhibits coupling between store depletion and SOCE activation.
Collapse
Affiliation(s)
- Khaled Machaca
- Department of Physiology and Biophysics, University of Arkansas Medical Science, Little Rock, 72205, USA.
| | | |
Collapse
|
30
|
Neilson J, Stankunas K, Crabtree GR. Monitoring the duration of antigen-receptor occupancy by calcineurin/glycogen-synthase-kinase-3 control of NF-AT nuclear shuttling. Curr Opin Immunol 2001; 13:346-50. [PMID: 11406367 DOI: 10.1016/s0952-7915(00)00225-9] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Recent structural studies have supported a kinetic model of TCR activation, raising the question of how the duration of receptor occupancy is translated into activation of immune response genes. We summarize evidence that the cytoplasmic-to-nuclear shuttling of NF-ATc family members monitors the duration of receptor occupancy.
Collapse
Affiliation(s)
- J Neilson
- Department of Microbiology and Immunology, Stanford University Medical School, 279 Campus Drive, 94305, Stanford, CA, USA
| | | | | |
Collapse
|
31
|
Stankunas K, Graef IA, Neilson JR, Park SH, Crabtree GR. Signaling through calcium, calcineurin, and NF-AT in lymphocyte activation and development. COLD SPRING HARBOR SYMPOSIA ON QUANTITATIVE BIOLOGY 2001; 64:505-16. [PMID: 11232327 DOI: 10.1101/sqb.1999.64.505] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
- K Stankunas
- Department of Developmental Biology and Department of Pathology, Howard Hughes Medical Institute, Stanford University Medical School, Stanford, California 94305, USA
| | | | | | | | | |
Collapse
|
32
|
Feske S, Giltnane J, Dolmetsch R, Staudt LM, Rao A. Gene regulation mediated by calcium signals in T lymphocytes. Nat Immunol 2001; 2:316-24. [PMID: 11276202 DOI: 10.1038/86318] [Citation(s) in RCA: 438] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Modulation of many signaling pathways in antigen-stimulated T and B cells results in global changes in gene expression. Here we investigate the contribution of calcium signaling to gene expression in T cells using cell lines from two severe-combined immunodeficiency patients with several cytokine deficiencies and diminished activation of the transcription factor NFAT nuclear factor of activated T cells. These T cells show a strong defect in transmembrane calcium influx that is also apparent in their B cells and fibroblasts. DNA microarray analysis of calcium entry-deficient and control T cells shows that Ca2+ signals both activate and repress gene expression and are largely transduced through the phosphatase calcineurin. We demonstrate an elaborate network of signaling pathways downstream of the T cell receptor, explaining the complexity of changes in gene expression during T cell activation.
Collapse
Affiliation(s)
- S Feske
- Center for Blood Research and Department of Pathology, Harvard Medical School, Boston, MA 02115, USA
| | | | | | | | | |
Collapse
|
33
|
Neal JW, Clipstone NA. Glycogen synthase kinase-3 inhibits the DNA binding activity of NFATc. J Biol Chem 2001; 276:3666-73. [PMID: 11063740 DOI: 10.1074/jbc.m004888200] [Citation(s) in RCA: 122] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The NFAT family of transcription factors is required for the expression of numerous immunologically important genes and plays a pivotal role in both the initiation and coordination of the immune response. NFAT family members appear to be regulated primarily at the level of their subcellular localization. Here we show that NFATc is additionally regulated at the level of its DNA binding activity. Using gel mobility shift assays, we demonstrate that the intrinsic DNA binding activity of NFATc is negatively regulated by phosphorylation. We found that activation of calcineurin activity in cells and dephosphorylation of NFATc in vitro enhanced NFATc DNA binding activity, whereas phosphorylation of NFATc in vitro inhibited its ability to bind DNA. Through the analysis of NFATc mutants, we identified the conserved Ser-Pro repeat motifs as critical quantitative determinants of NFATc DNA binding activity. In addition, we provide several lines of evidence to suggest that the phosphorylation of the Ser-Pro repeats by glycogen synthase kinase-3 inhibits the ability of NFATc to bind DNA. Taken together, these studies afford new insights into the regulation of NFATc and underscore the potential role of glycogen synthase kinase-3 in the regulation of NFAT-dependent gene expression.
Collapse
Affiliation(s)
- J W Neal
- Department of Microbiology-Immunology, Northwestern University Medical School, Chicago, Illinois 60611, USA
| | | |
Collapse
|
34
|
Affiliation(s)
- G R Crabtree
- Department of Developmental Biology and Department of Pathology, Stanford University Medical School, California 94305, USA.
| |
Collapse
|
35
|
Kotarsky K, Owman C, Olde B. A chimeric reporter gene allowing for clone selection and high-throughput screening of reporter cell lines expressing G-protein-coupled receptors. Anal Biochem 2001; 288:209-15. [PMID: 11152592 DOI: 10.1006/abio.2000.4898] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Efficient screening of ligands interacting with G-protein-coupled receptors is central for modern drug development. Here, we describe an optimized reporter vector primarily intended for use in reporter cell lines expressing such receptors. The construct consists of a synthetic enhancer containing 9x TRE (12-O-tetradecanoylphorbol-13-acetate-responsive elements) fused to a minimal CMV (cytomegalovirus) promoter. Activation of the promoter construct leads to the expression of a chimeric reporter protein based on the genes for enhanced green fluorescent protein and Photinus luciferase. The chimeric protein allows for both clonal selection by fluorescence, which facilitates the selection of optimal reporter cell lines and high-throughput screening by luminescens. In designing the vector, increasing numbers of TRE motifs were tested in front of two different minimal promoters. The reporter gene was more strongly inducible with increasing numbers of TRE motifs. The constructs were tested in two cell lines, CHO and HeLa. The latter regulated reporter gene activity stronger in response to PMA (phorbol 12-myristate 13-acetate) stimulation and were used to construct HF1 reporter cell lines. Model experiments were carried out on these reporter cells transfected with the human BLTR, human CCR5, or the rat alpha(1b) receptor. After maximal agonist stimulation reporter gene activity was increased 200-, 15-, and 50-fold, respectively.
Collapse
Affiliation(s)
- K Kotarsky
- Division of Molecular Neurobiology, Wallenberg Neuroscience Center, Lund, SE-223 62, Sweden.
| | | | | |
Collapse
|
36
|
Machaca K, Haun S. Store-operated calcium entry inactivates at the germinal vesicle breakdown stage of Xenopus meiosis. J Biol Chem 2000; 275:38710-5. [PMID: 10991950 PMCID: PMC1201341 DOI: 10.1074/jbc.m007887200] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Store-operated calcium entry (SOCE) is the predominant Ca(2+) influx pathway in non-excitable cells and is activated in response to depletion of intracellular Ca(2+) stores. We have studied SOCE regulation during Xenopus oocyte meiosis. SOCE can be measured readily in stage VI Xenopus oocytes arrested at the G(2)-M transition of the cell cycle, either by Ca(2+) imaging or by recording the SOCE current. However, following meiotic maturation, SOCE can no longer be activated by store depletion. We have characterized the time course of SOCE inactivation during oocyte maturation, and show that SOCE inactivates almost completely, in a very short time period, at the germinal vesicle breakdown stage of meiosis. This acute inactivation offers an opportunity to better understand SOCE regulation.
Collapse
Affiliation(s)
- K Machaca
- Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205, USA.
| | | |
Collapse
|
37
|
Bikah G, Pogue-Caley RR, McHeyzer-Williams LJ, McHeyzer-Williams MG. Regulating T helper cell immunity through antigen responsiveness and calcium entry. Nat Immunol 2000; 1:402-12. [PMID: 11062500 DOI: 10.1038/80841] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
We evaluated changes in the signaling potentials and proliferative capacity of single antigen-specific T helper (TH) cells during a primary immune response to a protein antigen. At the peak of cellular expansion in vivo all antigen-specific TH cells exhibited a profound block in CD3- and CD4-mediated mobilization of intracellular calcium together with a more global block in T cell receptor-independent capacitative calcium entry (CCE). The proliferative response of these antigen-specific TH cells to anti-CD3, anti-CD28 and IL-2 was also severely blunted. Cross-linking CD69 on a substantial fraction of CD69+ antigen-specific TH cells relieved this block in CCE and restored proliferative capacity in vitro. The CCE rescue operated through a CD69-coupled G protein and required calcium-bound calmodulin and calcineurin. These data reveal critical changes in the responsiveness of antigen-specific TH cells and provide evidence of new mechanisms for the regulation of antigen-specific TH cell development in vivo.
Collapse
Affiliation(s)
- G Bikah
- Department of Immunology, Duke University Medical Center, Durham, NC 27710, USA
| | | | | | | |
Collapse
|
38
|
Chen XP, Ding X, Daynes RA. Ganglioside control over IL-4 priming and cytokine production in activated T cells. Cytokine 2000; 12:972-85. [PMID: 10880242 DOI: 10.1006/cyto.1999.0596] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Our previous studies have shown that the enzymatic activities of Neu-1, an endogenous sialidase encoded in the murine MHC, are involved in promoting IL-4 synthesis by naive CD4(+)T cells. Our present studies have characterized responsible sialoconjugate targets of Neu-1 and questioned possible biochemical mechanisms responsible for their regulatory influences on IL-4 gene expression. These studies determined that treatment of T cells with the naturally occurring ganglioside GM3 inhibited the production of IL-4 without affecting the production of IL-2. An analysis of IL-4-primed CD4(+)T cells further demonstrated that GM3 treatment specifically inhibited the restimulated production of IL-4, IL-5 and IL-13, without inhibiting the production of IL-2 and IFN-gamma. The inhibitory effects of GM3 could be overcome by treatment with thapsigargin or ionomycin, suggesting ganglioside regulation occurs upstream of activation-induced calcium mobilization. GM3 treatment attenuated the level of calcium influx following CD3epsilon crosslinking, and CD4(+)T cells from Neu-1-deficient B10.SM strain mice (neu-1(a)and IL-4-deficient) expressed reduced levels of intracellular calcium following activation. Our results indicate that activities by membrane gangliosides can influence the cytokine programs in CD4(+)T cells, possibly through the modulation of calcium responses induced by T cell activation.
Collapse
Affiliation(s)
- X P Chen
- Department of Pathology, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
| | | | | |
Collapse
|
39
|
Okada T, Inoue R, Yamazaki K, Maeda A, Kurosaki T, Yamakuni T, Tanaka I, Shimizu S, Ikenaka K, Imoto K, Mori Y. Molecular and functional characterization of a novel mouse transient receptor potential protein homologue TRP7. Ca(2+)-permeable cation channel that is constitutively activated and enhanced by stimulation of G protein-coupled receptor. J Biol Chem 1999; 274:27359-70. [PMID: 10488066 DOI: 10.1074/jbc.274.39.27359] [Citation(s) in RCA: 364] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Characterization of mammalian homologues of Drosophila transient receptor potential protein (TRP) is an important clue to understand molecular mechanisms underlying Ca(2+) influx activated in response to stimulation of G(q) protein-coupled receptors in vertebrate cells. Here we have isolated cDNA encoding a novel seventh mammalian TRP homologue, TRP7, from mouse brain. TRP7 showed abundant RNA expression in the heart, lung, and eye and moderate expression in the brain, spleen, and testis. TRP7 recombinantly expressed in human embryonic kidney cells exhibited distinctive functional features, compared with other TRP homologues. Basal influx activity accompanied by reduction in Ca(2+) release from internal stores was characteristic of TRP7-expressing cells but was by far less significant in cells expressing TRP3, which is structurally the closest to TRP7 in the TRP family. TRP7 induced Ca(2+) influx in response to ATP receptor stimulation at ATP concentrations lower than those necessary for activation of TRP3 and for Ca(2+) release from the intracellular store, which suggests that the TRP7 channel is activated independently of Ca(2+) release. In fact, TRP7 expression did not affect capacitative Ca(2+) entry induced by thapsigargin, whereas TRP7 greatly potentiated Mn(2+) influx induced by diacylglycerols without involvement of protein kinase C. Nystatin-perforated and conventional whole-cell patch clamp recordings from TRP7-expressing cells demonstrated the constitutively activated and ATP-enhanced inward cation currents, both of which were initially blocked and then subsequently facilitated by extracellular Ca(2+) at a physiological concentration. Impairment of TRP7 currents by internal perfusion of the Ca(2+) chelator 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid revealed an essential role of intracellular Ca(2+) in activation of TRP7, and their potent activation by the diacylglycerol analogue suggests that the TRP7 channel is a new member of diacylglycerol-activated cation channels. Relative permeabilities indicate that TRP7 is slightly selective to divalent cations. Thus, our findings reveal an interesting correspondence of TRP7 to the background and receptor stimulation-induced cation currents in various native systems.
Collapse
Affiliation(s)
- T Okada
- Laboratory of Humoral Information, Department of Information Physiology, National Institute for Physiological Sciences, Okazaki 444-8585, Japan
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
40
|
Haque S, Dumon H, Haque A, Kasper LH. Alteration of Intracellular Calcium Flux and Impairment of Nuclear Factor-AT Translocation in T Cells During Acute Toxoplasma gondii Infection in Mice. THE JOURNAL OF IMMUNOLOGY 1998. [DOI: 10.4049/jimmunol.161.12.6812] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Abstract
Down-regulation of host immune response to Toxoplasma gondii is associated with the expression of specific cytokines, in particular IL-10, and the induction of CD4+ T cell anergy. In the present study we report that the expression of both CD4 and CD2 antigen is down-regulated during the acute phase of infection. A decrease in the expression of CD2 was apparent during the acute phase of T. gondii infection in three genetically distinct strains of mice, CBA/J, C57BL/6, and BALB/c. The lymphoproliferative response induced by cross-linked anti-CD3 mAb or by Con A was markedly depressed. This suppressed response was associated with a reduction in the influx of Ca2+. We have examined whether lymphocytes from T. gondii mice maintain NF-AT transcription factors in the nucleus where they participate in the Ca2+-dependent induction of genes required for lymphocyte activation and proliferation. Immunofluorescence with confocal microscopy using an Ab to NF-ATc demonstrates a decrease in translocation of NF-ATc in T lymphocytes from acutely infected mice. Together, these results suggest that the defect in T cell expansion that occurs during acute murine toxoplasmosis is related to reduced activity of NF-AT, a calcium-dependent transcription factor required for T cell proliferation.
Collapse
Affiliation(s)
- Sakhina Haque
- *Department of Medicine and Microbiology, Dartmouth Medical School, Hanover, NH 03755; and
- †Immunologie et Génétique Des Maladies Parasitaires, Institut National de la Santé et de la Recherche Médicale Unit 399, Faculté de Médecine, Marseille, France
| | - Henri Dumon
- †Immunologie et Génétique Des Maladies Parasitaires, Institut National de la Santé et de la Recherche Médicale Unit 399, Faculté de Médecine, Marseille, France
| | - Azizul Haque
- †Immunologie et Génétique Des Maladies Parasitaires, Institut National de la Santé et de la Recherche Médicale Unit 399, Faculté de Médecine, Marseille, France
| | - Lloyd H. Kasper
- *Department of Medicine and Microbiology, Dartmouth Medical School, Hanover, NH 03755; and
| |
Collapse
|
41
|
Rivera I, Harhaj EW, Sun SC. Involvement of NF-AT in type I human T-cell leukemia virus Tax-mediated Fas ligand promoter transactivation. J Biol Chem 1998; 273:22382-8. [PMID: 9712859 DOI: 10.1074/jbc.273.35.22382] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Human T-cell leukemia virus type I (HTLV-I)-infected T-cells constitutively express surface Fas ligand (FasL), which may serve as a mechanism of viral pathogenesis. HTLV-I induces transcription of FasL gene through the viral transactivator Tax, although the underlying molecular mechanism remains unclear. In the present study, we have analyzed both the cis-activating element and transactivating factors involved in Tax activation of the FasL promoter. We show that the 486-base pair upstream region of the human FasL gene is sufficient for Tax-mediated transactivation in Jurkat T-cells. Interestingly, a palindromic DNA sequence (GGAAACTTCC) covering the consensus NF-ATp binding site (GGAAA), is required for Tax activation of FasL promoter. The involvement of NF-AT in this transactivation event is suggested by the finding that Tax fails to activate the FasL promoter in a Jurkat T-cell line defective in capacitative calcium entry, a signaling mechanism involved in NF-AT activation. Furthermore, activation of FasL promoter by Tax is largely attenuated in the nonlymphoid F9 embryonal and COS kidney cells deficient in NF-ATp expression. DNA-protein interaction assays reveal that the NF-AT-like motif in the FasL promoter is bound by both NF-ATp and NF-AT4 in Jurkat T-cells expressing Tax. The binding of NF-ATp, although not NF-AT4, to this enhancer also occurs along with HTLV-I-mediated infection of human peripheral blood T-cells. Furthermore, exogenously transfected NF-ATp binds to the NF-AT-like enhancer and participates in Tax-mediated FasL promoter transactivation. These results suggest an important role for proteins of the NF-AT family in HTLV-I Tax-mediated FasL gene transactivation.
Collapse
Affiliation(s)
- I Rivera
- Department of Microbiology and Immunology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033, USA
| | | | | |
Collapse
|
42
|
Bunnell SC, Berg LJ. The signal transduction of motion and antigen recognition: factors affecting T cell function and differentiation. GENETIC ENGINEERING 1998; 20:63-110. [PMID: 9666556 DOI: 10.1007/978-1-4899-1739-3_4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- S C Bunnell
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA
| | | |
Collapse
|
43
|
Holsinger LJ, Graef IA, Swat W, Chi T, Bautista DM, Davidson L, Lewis RS, Alt FW, Crabtree GR. Defects in actin-cap formation in Vav-deficient mice implicate an actin requirement for lymphocyte signal transduction. Curr Biol 1998; 8:563-72. [PMID: 9601640 DOI: 10.1016/s0960-9822(98)70225-8] [Citation(s) in RCA: 344] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
BACKGROUND Antigen-receptor interactions on lymphocytes result in local clustering of actin, receptors and signaling molecules into an asymmetric membrane structure termed a cap. Although actin polymerization is known to be required, the mechanisms underlying cap formation are unclear. We have studied the events underlying cap formation using mice bearing a null mutation in vav (vav-/-), a gene that encodes a guanine-nucleotide exchange factor for the GTPase Rac. RESULTS Lymphocytes from vav-/- mice failed to form T-cell receptor caps following activation and had a defective actin cytoskeleton. The vav-/- T cells were deficient in interleukin-2 (IL-2) production and proliferation, and the peak of Ca2+ mobilization was reduced although of normal duration. Activation of Jun N-terminal kinase or stress-activated kinase (JNK or SAPK) and mitogen-activated protein kinase (MAPK) and the induction of the transcription factor NF-ATc1 and egr-1 genes was normal. Despite the reduced Ca2+ mobilization, translocation of cytoplasmic NF-ATc to the nucleus was normal, reflecting that the lower levels of Ca2+ in vav-/- cells were still sufficient to activate calcineurin. Treatment of lymphocytes with cytochalasin D, which blocks actin polymerization, inhibited cap formation and produced defects in signaling and IL-2 transcriptional induction in response to antigen-receptor signaling that were nearly identical to those seen in vav-/- cells. In transfection studies, either constitutively active Vav or Rac could complement constitutively active calcineurin to activate NF-AT-dependent transcription. CONCLUSIONS These results indicate that Vav is required for cap formation in lymphocytes. Furthermore, the correlation between cap formation, IL-2 production and proliferation supports the hypothesis that an actin-dependent pathway is a source of specialized growth regulatory signals.
Collapse
Affiliation(s)
- L J Holsinger
- Department of Pathology, Howard Hughes Medical Institute, Beckman Center for Molecular and Genetic Medicine, Stanford University School of Medicine, California 94305, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
44
|
Okada T, Shimizu S, Wakamori M, Maeda A, Kurosaki T, Takada N, Imoto K, Mori Y. Molecular cloning and functional characterization of a novel receptor-activated TRP Ca2+ channel from mouse brain. J Biol Chem 1998; 273:10279-87. [PMID: 9553080 DOI: 10.1074/jbc.273.17.10279] [Citation(s) in RCA: 223] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Characterization of mammalian homologues of Drosophila TRP proteins, which induce light-activated Ca2+ conductance in photoreceptors, has been an important clue to understand molecular mechanisms underlying receptor-activated Ca2+ influx in vertebrate cells. We have here isolated cDNA that encodes a novel TRP homologue, TRP5, predominantly expressed in the brain. Recombinant expression of the TRP5 cDNA in human embryonic kidney cells dramatically potentiated extracellular Ca2+-dependent rises of intracellular Ca2+ concentration ([Ca2+]i) evoked by ATP. These [Ca2+]i transients were inhibited by SK&F96365, a blocker of receptor-activated Ca2+ entry, and by La3+. Expression of the TRP5 cDNA, however, did not significantly affect [Ca2+]i transients induced by thapsigargin, an inhibitor of endoplasmic reticulum Ca2+-ATPases. ATP stimulation of TRP5-transfected cells pretreated with thapsigargin to deplete internal Ca2+ stores caused intact extracellular Ca2+-dependent [Ca2+]i transients, whereas ATP suppressed [Ca2+]i in thapsigargin-pretreated control cells. Furthermore, in ATP-stimulated, TRP5-expressing cells, there was no significant correlation between Ca2+ release from the internal Ca2+ store and influx of extracellular Ca2+. Whole-cell mode of patch-clamp recording from TRP5-expressing cells demonstrated that ATP application induced a large inward current in the presence of extracellular Ca2+. Omission of Ca2+ from intrapipette solution abolished the current in TRP5-expressing cells, whereas 10 nM intrapipette Ca2+ was sufficient to support TRP5 activity triggered by ATP receptor stimulation. Permeability ratios estimated from the zero-current potentials of this current were PCa:PNa:PCs = 14.3:1. 5:1. Our findings suggest that TRP5 directs the formation of a Ca2+-selective ion channel activated by receptor stimulation through a pathway that involves Ca2+ but not depletion of Ca2+ store in mammalian cells.
Collapse
Affiliation(s)
- T Okada
- Department of Information Physiology, National Institute for Physiological Sciences, Okazaki 444, Japan
| | | | | | | | | | | | | | | |
Collapse
|
45
|
Esser MT, Haverstick DM, Fuller CL, Gullo CA, Braciale VL. Ca2+ signaling modulates cytolytic T lymphocyte effector functions. J Exp Med 1998; 187:1057-67. [PMID: 9529322 PMCID: PMC2212215 DOI: 10.1084/jem.187.7.1057] [Citation(s) in RCA: 73] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/1997] [Revised: 12/05/1997] [Indexed: 11/16/2022] Open
Abstract
Cytolytic T cells use two mechanisms to kill virally infected cells, tumor cells, or other potentially autoreactive T cells in short-term in vitro assays. The perforin/granule exocytosis mechanism uses preformed cytolytic granules that are delivered to the target cell to induce apoptosis and eventual lysis. FasL/Fas (CD95 ligand/CD95)-mediated cytolysis requires de novo protein synthesis of FasL by the CTL and the presence of the death receptor Fas on the target cell to induce apoptosis. Using a CD8(+) CTL clone that kills via both the perforin/granule exocytosis and FasL/Fas mechanisms, and a clone that kills via the FasL/Fas mechanism only, we have examined the requirement of intra- and extracellular Ca2+ in TCR-triggered cytolytic effector function. These two clones, a panel of Ca2+ antagonists, and agonists were used to determine that a large biphasic increase in intracellular calcium concentration, characterized by release of Ca2+ from intracellular stores followed by a sustained influx of extracellular Ca2+, is required for perforin/granule exocytosis. Only the sustained influx of extracellular Ca2+ is required for FasL induction and killing. Thapsigargin, at low concentrations, induces this small but sustained increase in [Ca2+]i and selectively induces FasL/Fas-mediated cytolysis but not granule exocytosis. These results further define the role of Ca2+ in perforin and FasL/Fas killing and demonstrate that differential Ca2+ signaling can modulate T cell effector functions.
Collapse
Affiliation(s)
- M T Esser
- Department of Microbiology, University of Virginia, Health Sciences Center, Charlottesville, Virginia 22908, USA
| | | | | | | | | |
Collapse
|
46
|
Fluckiger AC, Li Z, Kato RM, Wahl MI, Ochs HD, Longnecker R, Kinet JP, Witte ON, Scharenberg AM, Rawlings DJ. Btk/Tec kinases regulate sustained increases in intracellular Ca2+ following B-cell receptor activation. EMBO J 1998; 17:1973-85. [PMID: 9524120 PMCID: PMC1170543 DOI: 10.1093/emboj/17.7.1973] [Citation(s) in RCA: 326] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Bruton's tyrosine kinase (Btk) is essential for B-lineage development and represents an emerging family of non-receptor tyrosine kinases implicated in signal transduction events initiated by a range of cell surface receptors. Increased dosage of Btk in normal B cells resulted in a striking enhancement of extracellular calcium influx following B-cell antigen receptor (BCR) cross-linking. Ectopic expression of Btk, or related Btk/Tec family kinases, restored deficient extracellular Ca2+ influx in a series of novel Btk-deficient human B-cell lines. Btk and phospholipase Cgamma (PLCgamma) co-expression resulted in tyrosine phosphorylation of PLCgamma and required the same Btk domains as those for Btk-dependent calcium influx. Receptor-dependent Btk activation led to enhanced peak inositol trisphosphate (IP3) generation and depletion of thapsigargin (Tg)-sensitive intracellular calcium stores. These results suggest that Btk maintains increased intracellular calcium levels by controlling a Tg-sensitive, IP3-gated calcium store(s) that regulates store-operated calcium entry. Overexpression of dominant-negative Syk dramatically reduced the initial phase calcium response, demonstrating that Btk/Tec and Syk family kinases may exert distinct effects on calcium signaling. Finally, co-cross-linking of the BCR and the inhibitory receptor, FcgammaRIIb1, completely abrogated Btk-dependent IP3 production and calcium store depletion. Together, these data demonstrate that Btk functions at a critical crossroads in the events controlling calcium signaling by regulating peak IP3 levels and calcium store depletion.
Collapse
Affiliation(s)
- A C Fluckiger
- Department of Microbiology and Molecular Genetics, University of California at Los Angeles, Los Angeles, CA 90095-1662, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
47
|
Zlokarnik G, Negulescu PA, Knapp TE, Mere L, Burres N, Feng L, Whitney M, Roemer K, Tsien RY. Quantitation of transcription and clonal selection of single living cells with beta-lactamase as reporter. Science 1998; 279:84-8. [PMID: 9417030 DOI: 10.1126/science.279.5347.84] [Citation(s) in RCA: 544] [Impact Index Per Article: 20.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Gene expression was visualized in single living mammalian cells with beta-lactamase as a reporter that hydrolyzes a substrate loaded intracellularly as a membrane-permeant ester. Each enzyme molecule changed the fluorescence of many substrate molecules from green to blue by disrupting resonance energy transfer. This wavelength shift was detectable by eye or color film in individual cells containing less than 100 beta-lactamase molecules. The robust change in emission ratio reveals quantitative heterogeneity in real-time gene expression, enables clonal selection by flow cytometry, and forms a basis for high-throughput screening of pharmaceutical candidate drugs in living mammalian cells.
Collapse
Affiliation(s)
- G Zlokarnik
- Aurora Biosciences, 11010 Torreyana Road, San Diego, CA 92121, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
48
|
Abstract
The discovery of a diverse and unique subset of ion channels in T lymphocytes has led to a rapidly growing body of knowledge about their functional roles in the immune system. Potent and specific blockers have provided molecular tools to probe channel structure-function relations and to elucidate the involvement of K+, Ca2+, and Cl- channels in T-cell activation and cell volume regulation. Recent advances in analyzing Kv1.3 channel structure-function relationships have defined binding sites for channel blockers, which have now been shown to be effective in suppressing T-cell function in vivo. Ion channels may provide excellent pharmaceutical targets for modulating immune system function.
Collapse
Affiliation(s)
- M D Cahalan
- Department of Physiology and Biophysics, University of California, Irvine 92697-4560, USA.
| | | |
Collapse
|
49
|
Alberola-Ila J, Takaki S, Kerner JD, Perlmutter RM. Differential signaling by lymphocyte antigen receptors. Annu Rev Immunol 1997; 15:125-54. [PMID: 9143684 DOI: 10.1146/annurev.immunol.15.1.125] [Citation(s) in RCA: 227] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Studies performed during the past several years make plain that ligand occupancy of antigen receptors need not necessarily provoke identical responses in all instances. For example, ligation of antigen receptors may stimulate a proliferative response, induce a state of unresponsiveness to subsequent stimulation (anergy), or induce apoptosis. How does a single type of transmembrane receptor induce these very heterogeneous cellular responses? In the following pages, we outline evidence supporting the view that the nature of the ligand/receptor interaction directs the physical recruitment of signaling pathways differentially inside the lymphocyte and hence defines the nature of the subsequent immune response. We begin by providing a functional categorization of antigen receptor components, considering the ways in which these components interact with the known set of signal transduction pathways, and then review the evidence suggesting that differential signaling through the TCR is achieved by qualitative differences in the effector pathways recruited by TCR, perhaps reflecting the time required to bring complicated signal transduction elements into proximity within the cell. The time-constant of the interaction between antigen and receptor in this way determines, at least in part, the nature of the resulting response. Finally, although our review focuses substantially on T cell receptor signaling, we have included a less detailed description of B cell receptor signaling as well, simply to emphasize the parallels that exist in these two closely related systems.
Collapse
Affiliation(s)
- J Alberola-Ila
- Department of Immunology, University of Washington, Seattle 98195, USA
| | | | | | | |
Collapse
|
50
|
Fischer A, Cavazzana-Calvo M, De Saint Basile G, DeVillartay JP, Di Santo JP, Hivroz C, Rieux-Laucat F, Le Deist F. Naturally occurring primary deficiencies of the immune system. Annu Rev Immunol 1997; 15:93-124. [PMID: 9143683 DOI: 10.1146/annurev.immunol.15.1.93] [Citation(s) in RCA: 130] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Naturally occurring genetic disorders of the immune system provide many models for the study of its development and function. In a way, their analysis complements the information provided by the generation of genetic defects in mice created using homologous recombination techniques. In this review, the recent findings made in three areas are focused upon deficiencies in T cell differentiation and in T lymphocyte activation, and on the control process of peripheral immune response.
Collapse
Affiliation(s)
- A Fischer
- Unité INSERM U 429, Hôpital Necker-Enfants Malades, Paris, France
| | | | | | | | | | | | | | | |
Collapse
|