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Kopach O, Pivneva T, Fedirko N, Voitenko N. Mitochondrial malfunction mediates impaired cholinergic Ca 2+ signalling and submandibular salivary gland dysfunction in diabetes. Neuropharmacology 2024; 243:109789. [PMID: 37972885 DOI: 10.1016/j.neuropharm.2023.109789] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2023] [Revised: 10/23/2023] [Accepted: 11/09/2023] [Indexed: 11/19/2023]
Abstract
Xerostomia (dry-mouth syndrome) is a painful and debilitating condition that frequently occurs in individuals with diabetes and is associated with impaired saliva production and salivary gland hypofunction. Saliva fluid production relies on Ca2+-coupled secretion driven by neurotransmitter stimulation of submandibular acinar cells. Although impairments in intracellular Ca2+ signalling have been reported in various xerostomia models, the specific Ca2+-dependent mechanisms underlying saliva fluid hypofunction in diabetes remain unclear. In this study, we show that diabetic animals exhibit severe xerostomia, evident by reduced saliva flow rate, diminished total protein content, and decreased amylase activity in the saliva secreted by submandibular glands. These impairments remained resistant to exogenous cholinergic stimulation. In submandibular acinar cells, the intracellular Ca2+ signals evoked by cholinergic stimulation were reduced and delayed in diabetes, caused by malfunctioning mitochondria. Upon initiation of cholinergic-evoked Ca2+ signals, mitochondria accumulate higher Ca2+ and fail to redistribute Ca2+ influx and facilitate the store-operated Ca2+ entry effectively. Structural damage to mitochondria was evident in the acinar cells in diabetes. These findings provide insights into the potential targeting of malfunctioning mitochondria for the treatment of diabetic xerostomia as an alternative strategy to the existing pharmacotherapeutic approaches. This article is part of the Special Issue on "Ukrainian Neuroscience".
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Affiliation(s)
- Olga Kopach
- Bogomoletz Institute of Physiology, Kyiv, Ukraine; Queen Square Institute of Neurology, University College London, London, UK.
| | - Tetyana Pivneva
- Bogomoletz Institute of Physiology, Kyiv, Ukraine; Kyiv Academic University, Kyiv, Ukraine
| | | | - Nana Voitenko
- Kyiv Academic University, Kyiv, Ukraine; Dobrobut Academy Medical School, Kyiv, Ukraine
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Samanta K, Bakowski D, Amin N, Parekh AB. The whole-cell Ca 2+ release-activated Ca 2+ current, I CRAC , is regulated by the mitochondrial Ca 2+ uniporter channel and is independent of extracellular and cytosolic Na . J Physiol 2019; 598:1753-1773. [PMID: 30582626 PMCID: PMC7318671 DOI: 10.1113/jp276551] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Accepted: 12/05/2018] [Indexed: 12/12/2022] Open
Abstract
Key points Ca2+ entry through Ca2+ release‐activated Ca2+ channels activates numerous cellular responses. Under physiological conditions of weak intracellular Ca2+ buffering, mitochondrial Ca2+ uptake regulates CRAC channel activity. Knockdown of the mitochondrial Ca2+ uniporter channel prevented the development of ICRAC in weak buffer but not when strong buffer was used instead. Removal of either extracellular or intra‐pipette Na+ had no effect on the selectivity, kinetics, amplitude, rectification or reversal potential of whole‐cell CRAC current. Knockdown of the mitochondrial Na+–Ca2+ exchanger did not prevent the development of ICRAC in strong or weak Ca2+ buffer. Whole cell CRAC current is Ca2+‐selective. Mitochondrial Ca2+ channels, and not Na+‐dependent transport, regulate CRAC channels under physiological conditions.
Abstract Ca2+ entry through store‐operated Ca2+ release‐activated Ca2+ (CRAC) channels plays a central role in activation of a range of cellular responses over broad spatial and temporal bandwidths. Mitochondria, through their ability to take up cytosolic Ca2+, are important regulators of CRAC channel activity under physiological conditions of weak intracellular Ca2+ buffering. The mitochondrial Ca2+ transporter(s) that regulates CRAC channels is unclear and could involve the 40 kDa mitochondrial Ca2+ uniporter (MCU) channel or the Na+–Ca2+–Li+ exchanger (NCLX). Here, we have investigated the involvement of these mitochondrial Ca2+ transporters in supporting the CRAC current (ICRAC) under a range of conditions in RBL mast cells. Knockdown of the MCU channel impaired the activation of ICRAC under physiological conditions of weak intracellular Ca2+ buffering. In strong Ca2+ buffer, knockdown of the MCU channel did not inhibit ICRAC development demonstrating that mitochondria regulate CRAC channels under physiological conditions by buffering of cytosolic Ca2+ via the MCU channel. Surprisingly, manipulations that altered extracellular Na+, cytosolic Na+ or both failed to inhibit the development of ICRAC in either strong or weak intracellular Ca2+ buffer. Knockdown of NCLX also did not affect ICRAC. Prolonged removal of external Na+ also had no significant effect on store‐operated Ca2+ entry, on cytosolic Ca2+ oscillations generated by receptor stimulation or on CRAC channel‐driven gene expression. In the RBL mast cell, Ca2+ flux through the MCU but not NCLX is indispensable for activation of ICRAC. Ca2+ entry through Ca2+ release‐activated Ca2+ channels activates numerous cellular responses. Under physiological conditions of weak intracellular Ca2+ buffering, mitochondrial Ca2+ uptake regulates CRAC channel activity. Knockdown of the mitochondrial Ca2+ uniporter channel prevented the development of ICRAC in weak buffer but not when strong buffer was used instead. Removal of either extracellular or intra‐pipette Na+ had no effect on the selectivity, kinetics, amplitude, rectification or reversal potential of whole‐cell CRAC current. Knockdown of the mitochondrial Na+–Ca2+ exchanger did not prevent the development of ICRAC in strong or weak Ca2+ buffer. Whole cell CRAC current is Ca2+‐selective. Mitochondrial Ca2+ channels, and not Na+‐dependent transport, regulate CRAC channels under physiological conditions.
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Affiliation(s)
- Krishna Samanta
- Department of Physiology, Anatomy and Genetics, University of Oxford, Sherrington Building, Parks Road, Oxford, OX1 3PT, UK
| | - Daniel Bakowski
- Department of Physiology, Anatomy and Genetics, University of Oxford, Sherrington Building, Parks Road, Oxford, OX1 3PT, UK
| | - Nader Amin
- Chemistry Research Laboratory, Department of Chemistry, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, UK
| | - Anant B Parekh
- Department of Physiology, Anatomy and Genetics, University of Oxford, Sherrington Building, Parks Road, Oxford, OX1 3PT, UK
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Yu L, Liu Q, Canning BJ. Evidence for autocrine and paracrine regulation of allergen-induced mast cell mediator release in the guinea pig airways. Eur J Pharmacol 2017; 822:108-118. [PMID: 29157985 DOI: 10.1016/j.ejphar.2017.11.017] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Revised: 11/09/2017] [Accepted: 11/13/2017] [Indexed: 02/06/2023]
Abstract
Mast cells play an essential role in immediate type hypersensitivity reactions and in chronic allergic diseases of the airways, including asthma. Mast cell mediator release can be modulated by locally released autacoids and circulating hormones, but surprisingly little is known about the autocrine effects of mediators released upon mast cell activation. We thus set out to characterize the autocrine and paracrine effects of mast cell mediators on mast cell activation in the guinea pig airways. By direct measures of histamine, cysteinyl-leukotriene and thromboxane release and with studies of allergen-evoked contractions of airway smooth muscle, we describe a complex interplay amongst these autacoids. Notably, we observed an autocrine effect of the cysteinyl-leukotrienes acting through cysLT1 receptors on mast cell leukotriene release. We confirmed the results of previous studies demonstrating a marked enhancement of mast cell mediator release following cyclooxygenase inhibition, but we have extended these results by showing that COX-2 derived eicosanoids inhibit cysteinyl-leukotriene release and yet are without effect on histamine release. Given the prominent role of COX-1 inhibition in aspirin-sensitive asthma, these data implicate preformed mediators stored in granules as the initial drivers of these adverse reactions. Finally, we describe the paracrine signaling cascade leading to thromboxane synthesis in the guinea pig airways following allergen challenge, which occurs indirectly, secondary to cysLT1 receptor activation on structural cells and/ or leukocytes within the airway wall, and a COX-2 dependent synthesis of the eicosanoid. The results highlight the importance of cell-cell and autocrine interactions in regulating allergic responses in the airways.
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Affiliation(s)
- Li Yu
- Department of Respiratory Medicine, Tongji Hospital, Tongii University School of Medicine, Shanghai 200065, China
| | - Qi Liu
- Johns Hopkins Asthma and Allergy Center, 5501 Hopkins Bayview Circle, Baltimore, MD 21224, USA
| | - Brendan J Canning
- Johns Hopkins Asthma and Allergy Center, 5501 Hopkins Bayview Circle, Baltimore, MD 21224, USA.
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Rahman S, Rahman T. Unveiling some FDA-approved drugs as inhibitors of the store-operated Ca 2+ entry pathway. Sci Rep 2017; 7:12881. [PMID: 29038464 PMCID: PMC5643495 DOI: 10.1038/s41598-017-13343-x] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Accepted: 09/21/2017] [Indexed: 11/16/2022] Open
Abstract
The store-operated calcium entry (SOCE) pathway is an important route for generating cytosolic Ca2+ signals that regulate a diverse array of biological processes. Abnormal SOCE seem to underlie several diseases that notably include allergy, inflammation and cancer. Therefore, any modulator of this pathway is likely to have significant impact in cell biology under both normal and abnormal conditions. In this study, we screened the FDA-approved drug library for agents that share significant similarity in 3D shape and surface electrostatics with few, hitherto best known inhibitors of SOCE. This has led to the identification of five drugs that showed dose-dependent inhibition of SOCE in cell-based assay, probably through interacting with the Orai1 protein which effectively mediates SOCE. Of these drugs, leflunomide and teriflunomide could suppress SOCE significantly at clinically-relevant doses and this provides for an additional mechanism towards the therapeutic utility of these drugs as immunosuppressants. The other three drugs namely lansoprazole, tolvaptan and roflumilast, were less potent in suppressing SOCE but were more selective and thus they may serve as novel scaffolds for future development of new, more efficacious SOCE inhibitors.
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Affiliation(s)
- Saifur Rahman
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge, UK
| | - Taufiq Rahman
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge, UK.
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Cysteinyl leukotriene type I receptor desensitization sustains Ca2+-dependent gene expression. Nature 2012; 482:111-5. [PMID: 22230957 PMCID: PMC3272478 DOI: 10.1038/nature10731] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2011] [Accepted: 11/23/2011] [Indexed: 12/03/2022]
Abstract
A universal mechanism to turn off a biological response is receptor desensitization, where the ability of a physiological trigger to activate a cell is lost despite the continued presence of the stimulus. Receptor desensitization of G protein-coupled receptors involves uncoupling of the receptor from its G protein/second messenger pathway, followed by receptor internalization1. G protein-coupled cysteinyl leukotriene type I (CysLT1) receptors regulate immune cell function and the receptor is an established therapeutic target for allergies including asthma2. Desensitization of these receptors arises predominantly from protein kinase C-dependent phosphorylation of three serine residues in the receptor C-terminus3. Physiological concentrations of the receptor agonist LTC4 evoke repetitive cytoplasmic Ca2+ oscillations, reflecting regenerative Ca2+ release from stores that is sustained by Ca2+ entry through store-operated CRAC channels4. CRAC channels are tightly linked to expression of the transcription factor c-fos5, a regulator of numerous genes important to cell growth and development6. Here we show that abolishing leukotriene receptor desensitization suppresses agonist-driven gene expression. Mechanistically, stimulation of non-desensitizing receptors evoked prolonged inositol trisphosphate-mediated Ca2+ release, which led to accelerated Ca2+-dependent slow inactivation of CRAC channels and a subsequent loss of excitation-transcription coupling. Rather than serving to turn off a biological response, reversible desensitization of a Ca2+ mobilizing receptor acts as an ‘on’switch, sustaining long-term signalling in the immune system.
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Kar P, Nelson C, Parekh AB. Selective activation of the transcription factor NFAT1 by calcium microdomains near Ca2+ release-activated Ca2+ (CRAC) channels. J Biol Chem 2011; 286:14795-803. [PMID: 21325277 DOI: 10.1074/jbc.m111.220582] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
NFATs are a family of Ca(2+)-dependent transcription factors that play a central role in the morphogenesis, development, and physiological activities of numerous distinct cell types and organ systems. Here, we visualize NFAT1 movement in and out of the nucleus in response to transient activation of store-operated Ca(2+) release-activated Ca(2+) (CRAC) channels in nonexcitable cells. We show that NFAT migration is exquisitely sensitive to Ca(2+) microdomains near open CRAC channels. Another Ca(2+)-permeable ion channel (TRPC3) was ineffective in driving NFAT1 to the nucleus. NFAT1 movement is temporally dissociated from the time course of the Ca(2+) signal and remains within the nucleus for 10 times longer than the duration of the trigger Ca(2+) signal. Kinetic analyses of each step linking CRAC channel activation to NFAT1 nuclear residency reveals that the rate-limiting step is transcription factor exit from the nucleus. The slow deactivation of NFAT provides a mechanism whereby Ca(2+)-dependent responses can be sustained despite the termination of the initial Ca(2+) signal and helps explain how gene expression in nonexcitable cells can continue after the primary stimulus has been removed.
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Affiliation(s)
- Pulak Kar
- Department of Physiology, Oxford University, Sherrington Building, Parks Road, Oxford OX1 3PT, United Kingdom
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15-HETE mediates sub-acute hypoxia-induced TRPC1 expression and enhanced capacitative calcium entry in rat distal pulmonary arterial myocytes. Prostaglandins Other Lipid Mediat 2010; 93:60-74. [PMID: 20599518 DOI: 10.1016/j.prostaglandins.2010.06.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2010] [Revised: 06/03/2010] [Accepted: 06/24/2010] [Indexed: 12/28/2022]
Abstract
Sub-acute hypoxia causes pulmonary vasoconstriction (HPV) is associated with increased intracellular Ca(2+) concentration ([Ca(2+)](i)) and contraction of pulmonary arterial smooth muscle cells (PASMCs). We previous have demonstrated that 15-hydroxyeicosatetraenoic acid (15-HETE), a metabolite of arachidonic acid by 15-lipoxygenase (15-LO), causes elevated [Ca(2+)](i) in PASMCs partly through Ca(2+) entry via other than L-type Ca(2+) channels. In this study, we used SKF96365/La(3+) (SOCC antagonists) and Nordihydro-guiairetic acid (NDGA, a blockage of 15-LO) to examine the effect of 15-HETE on capacitative Ca(2+) entry and activity/expression of store-operated Ca(2+) channels (SOCCs) during sub-acute hypoxic procedure and the contribution of SOCCs on the maintenance of vascular tones. The results showed that the 15-HETE induced constriction of PA rings from normoxic and sub-acute hypoxic rats can be abolished by SKF96365 and La(3+). Capacitative Ca(2+) entry (CCE) was also enhanced in PASMCs cultured with 15-HETE under sub-acute hypoxic condition (3% O(2), 48h) and incubation with NDGA in PASMCs can greatly suppress this enhancement. Moreover, TRPC1, not TRPC4 and TRPC6, mRNA and protein expression were increased in PASMCs during these procedures. Meanwhile, the effect of 15-HETE on CCE and TRPC1 expression under sub-acute hypoxic cultivation were greatly suppressed in 15-LO knockdown PASMCs and PAs. These results suggest that 15-HETE mediated HPV through increased TRPC1 expression, leading to enhanced CCE, contributing to the maintenance of vascular tone.
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Dietrich HH, Abendschein DR, Moon SH, Nayeb-Hashemi N, Mancuso DJ, Jenkins CM, Kaltenbronn KM, Blumer KJ, Turk J, Gross RW. Genetic ablation of calcium-independent phospholipase A(2)beta causes hypercontractility and markedly attenuates endothelium-dependent relaxation to acetylcholine. Am J Physiol Heart Circ Physiol 2010; 298:H2208-20. [PMID: 20382858 DOI: 10.1152/ajpheart.00839.2009] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Activation of phospholipases leads to the release of arachidonic acid and lysophospholipids that play prominent roles in regulating vasomotor tone. To identify the role of calcium-independent phospholipase A(2)beta (iPLA(2)beta) in vasomotor function, we measured vascular responses to phenylephrine (PE) and ACh in mesenteric arterioles from wild-type (WT; iPLA(2)beta(+/+)) mice and those lacking the beta-isoform (iPLA(2)beta(-/-)) both ex vivo and in vivo. Vessels isolated from iPLA(2)beta(-/-) mice demonstrated increased constriction to PE, despite lower basal smooth muscle calcium levels, and decreased vasodilation to ACh compared with iPLA(2)beta(+/+) mice. PE constriction resulted in initial intracellular calcium release with subsequent steady-state constriction that depended on extracellular calcium influx. Endothelial denudation had no effect on vessel tone or PE-induced constriction although the dilation to ACh was significantly reduced in iPLA(2)beta(+/+) vessels. In contrast, vessels from iPLA(2)beta(-/-) constricted by 54% after denudation, indicating smooth muscle hypercontractility. In vivo, blood pressure, resting vessel diameter, and constriction of mesenteric vessels to PE were not different in iPLA(2)beta(-/-) vessels compared with WT mouse vessels. However, relaxation after ACh administration in situ was attenuated, indicating an endothelial inability to induce dilation in response to ACh. In cultured endothelial cells, inhibition of iPLA(2)beta with (S)-(E)-6-(bromomethylene)tetrahydro-3-(1-naphthalenyl)-2H-pyran-2-one (BEL) decreased endothelial nitric oxide synthase phosphorylation and reduced endothelial agonist-induced intracellular calcium release as well as extracellular calcium influx. We conclude that iPLA(2)beta is an important mediator of vascular relaxation and intracellular calcium homeostasis in both smooth muscle and endothelial cells and that ablation of iPLA(2)beta causes agonist-induced smooth muscle hypercontractility and reduced agonist-induced endothelial dilation.
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Affiliation(s)
- Hans H Dietrich
- Washington Univ. School of Medicine, Dept. of Neurosurgery, 660 South Euclid Ave., Campus Box 8057, St. Louis, MO 63110, USA.
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Di Capite J, Nelson C, Bates G, Parekh AB. Targeting Ca2+ release-activated Ca2+ channel channels and leukotriene receptors provides a novel combination strategy for treating nasal polyposis. J Allergy Clin Immunol 2009; 124:1014-21.e1-3. [PMID: 19895990 DOI: 10.1016/j.jaci.2009.08.030] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2009] [Revised: 07/16/2009] [Accepted: 08/03/2009] [Indexed: 11/24/2022]
Abstract
BACKGROUND Nasal polyposis is a chronic inflammatory disease of the upper respiratory tract that affects around 2% of the population and almost 67% of patients with aspirin-intolerant asthma. Polyps are rich in mast cells and eosinophils, resulting in high levels of the proinflammatory cysteinyl leukotrienes. OBJECTIVES To better understand the role of the proinflammatory leukotrienes in nasal polyposis, we asked the following questions: (1) How do nasal polyps produce leukotriene C(4) (LTC(4))? (2) Can LTC(4) feed back in a paracrine way to maintain mast cell activation? (3) Could a combination therapy targeting the elements of this feed-forward loop provide a novel therapy for allergic disease? METHODS We have used immunohistochemistry, enzyme immunoassay, and cytoplasmic calcium ion (Ca(2+)) imaging to address these questions on cultured and acutely isolated human mast cells from patients with polyposis. RESULTS Ca(2+) entry through store-operated Ca(2+) release-activated Ca(2+) (CRAC) channels in polyps produced LTC(4) in a manner dependent on protein kinase C. LTC(4) thus generated activated mast cells through cysteinyl leukotriene type I receptors. Hence Ca(2+) influx into mast cells stimulates LTC(4) production, which then acts as a paracrine signal to activate further Ca(2+) influx. A combination of a low concentration of both a CRAC channel blocker and a leukotriene receptor antagonist was as effective at suppressing mast cell activation as a high concentration of either antagonist alone. CONCLUSION A drug combination directed against CRAC channels and leukotriene receptor antagonist suppresses the feed-forward loop that leads to aberrant mast cell activation. Hence our results identify a new potential strategy for combating polyposis and mast cell-dependent allergies.
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Affiliation(s)
- Joseph Di Capite
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
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Lin TY, London CA. Characterization and modulation of canine mast cell derived eicosanoids. Vet Immunol Immunopathol 2009; 135:118-127. [PMID: 20036014 DOI: 10.1016/j.vetimm.2009.11.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2009] [Revised: 10/23/2009] [Accepted: 11/16/2009] [Indexed: 01/29/2023]
Abstract
Mast cells play an important role in both innate and acquired immunity as well as several pathological conditions including allergy, arthritis and neoplasia. They influence these processes by producing a variety of mediators including cytokines, chemokines and eicosanoids. Very little is currently known about the spectrum of inflammatory mediators, particularly eicosanoids (prostaglandins and leukotrienes), produced by canine mast cells. This is important since modulating mast cell derived eicosanoids may help in the treatment of autoimmune and inflammatory disorders. The purpose of this study was to investigate the spectrum of eicosanoids produced by normal canine mast cells and to evaluate the effects of cytokines and non-steroidal anti-inflammatory mediators (NSAIDS) on eicosanoid production and release. Canine bone marrow derived cultured mast cells (cBMCMCs) expressed COX-1, COX-2, and 5-LOX and synthesized and released PGD2, PGE2, LTB4, and LTC4 following activation by a variety of stimuli. The selective COX-2 NSAIDs carprofen (Rimadyl) and deracoxib (Deramaxx) inhibited PGD2 and PGE2 production but only slightly inhibited LTB4 and LTC4. The mixed COX-1/COX-2 inhibitor piroxicam blocked PGD2 and PGE2 production, but upregulated LTC4 following treatment while tepoxilan (Zubrin), a pan COX/LOX inhibitor, markedly reduced the production of all eicosanoids. The LOX inhibitor nordihydroguaiaretic acid (NDGA) prevented LTB4/LTC4 release and BMBMC degranulation. Pre-incubation of cBMCMCs with IL-4 and SCF sensitized these cells to degranulation in response to substance P. In conclusion, canine BMCMCs produce an array of eicosanoids similar to those produced by mast cells from other species. Tepoxilan appeared to be the most effective NSAID for blocking eicosanoid production and thus may be useful for modulating mast cell mediated responses in dogs.
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Affiliation(s)
- Tzu-Yin Lin
- Department of Veterinary Biosciences, College of Veterinary Medicine, The Ohio State University, 454 VMAB, 1925 Coffey Road, Columbus, OH 43210, USA
| | - Cheryl A London
- Department of Veterinary Biosciences, College of Veterinary Medicine, The Ohio State University, 454 VMAB, 1925 Coffey Road, Columbus, OH 43210, USA.
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Gong YZ, Ding WG, Wu J, Tsuji K, Horie M, Matsuura H. Cinnamyl-3,4-dihydroxy-α-cyanocinnamate and nordihydroguaiaretic acid inhibit human Kv1.5 currents independently of lipoxygenase. Eur J Pharmacol 2008; 600:18-25. [DOI: 10.1016/j.ejphar.2008.10.010] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2008] [Revised: 09/15/2008] [Accepted: 10/05/2008] [Indexed: 10/21/2022]
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12
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Li YS, Wu P, Zhou XY, Chen JG, Cai L, Wang F, Xu LM, Zhang XL, Chen Y, Liu SJ, Huang YP, Ye DY. Formyl-peptide receptor like 1: A potent mediator of the Ca2+ release-activated Ca2+ current ICRAC. Arch Biochem Biophys 2008; 478:110-8. [DOI: 10.1016/j.abb.2008.07.002] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2008] [Revised: 06/28/2008] [Accepted: 07/04/2008] [Indexed: 10/21/2022]
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Inhibitory effect of xanthones isolated from the pericarp of Garcinia mangostana L. on rat basophilic leukemia RBL-2H3 cell degranulation. Bioorg Med Chem 2008; 16:4500-8. [DOI: 10.1016/j.bmc.2008.02.054] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2008] [Revised: 02/14/2008] [Accepted: 02/15/2008] [Indexed: 01/25/2023]
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14
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Bakowski D, Parekh AB. Regulation of store-operated calcium channels by the intermediary metabolite pyruvic acid. Curr Biol 2007; 17:1076-81. [PMID: 17570667 DOI: 10.1016/j.cub.2007.05.041] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2007] [Revised: 05/11/2007] [Accepted: 05/15/2007] [Indexed: 11/20/2022]
Abstract
A rise in cytosolic Ca(2+) concentration is used as a key activation signal in virtually all animal cells, where it triggers a range of responses, including neurotransmitter release, muscle contraction, and cell growth and proliferation. A major route for Ca(2+) influx is through store-operated Ca(2+) channels. One important intracellular target for Ca(2+) entry through store-operated channels is the mitochondrion, which increases aerobic metabolism and ATP production after Ca(2+) uptake. Here, we reveal a novel feedback pathway whereby pyruvic acid, a critical rate-limiting substrate for mitochondrial respiration, increases store-operated entry by reducing inactivation of the channels. Importantly, the effects of pyruvic acid are manifest at physiologically relevant concentrations and membrane potentials. The reduction in the inactivation of calcium release-activated calcium (CRAC) channels by pyruvate is highly specific in that it is not mimicked by other intermediary metabolic acids, does not require its metabolism, is independent of its Ca(2+) buffering action, and does not involve mitochondrial Ca(2+) uptake or ATP production. These results reveal a new and direct link between intermediary metabolism and ion-channel gating and identify pyruvate as a potential signaling messenger linking energy demand to calcium-channel function.
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Affiliation(s)
- Daniel Bakowski
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Parks Road, Oxford OX1 3PT, United Kingdom
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15
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Kim TH, Kim HI, Song JH. Effects of nordihydroguaiaretic acid on Na+ currents in rat dorsal root ganglion neurons. Brain Res 2006; 1072:62-71. [PMID: 16423329 DOI: 10.1016/j.brainres.2005.12.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2005] [Revised: 11/30/2005] [Accepted: 12/05/2005] [Indexed: 11/15/2022]
Abstract
Nordihydroguaiaretic acid (NDGA) is a lipoxygenase (LO) inhibitor with a strong antioxidant activity. It attenuates nociceptive responses produced by various stimuli, which has been ascribed to its LO inhibition. Primary sensory neurons express multiple Na+ channels that are important in processing normal and abnormal nociception. We examined the effects of NDGA on tetrodotoxin-sensitive and tetrodotoxin-resistant Na+ currents in rat dorsal root ganglion neurons. NDGA inhibited both types of Na+ currents concentration dependently and reversibly. Both activation and inactivation time courses were slowed by NDGA, which were not reversible. NDGA produced a hyperpolarizing shift of the steady-state inactivation curves and reduced the maximal availability of both Na+ currents, indicating that it blocks both inactivated and resting Na+ channels. NDGA shifted the conductance-voltage curves of both Na+ currents toward a depolarizing direction and increased the slope factors of the curves. The recovery of Na+ channels from inactivation was retarded by NDGA. All these effects will reduce the excitability of sensory neurons and should be taken into account when it comes to the antinociceptive effects of NDGA.
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Affiliation(s)
- Tae Hoon Kim
- Department of Pharmacology, Chung-Ang University, College of Medicine, 221 Heuksuk-Dong, Dongjak-Ku, Seoul 156-756, Republic of Korea
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Martínez J, Moreno JJ. Role of Ca2+-independent phospholipase A2 and cytochrome P-450 in store-operated calcium entry in 3T6 fibroblasts. Biochem Pharmacol 2005; 70:733-9. [PMID: 15993852 DOI: 10.1016/j.bcp.2005.04.045] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2004] [Accepted: 04/29/2005] [Indexed: 11/18/2022]
Abstract
Store-operated calcium (SOC) channels and capacitative Ca2+ entry play a key role in cellular functions, but their mechanism of activation remains unclear. Here, we show that thapsigargin induces [3H] arachidonic acid (AA) release, 45Ca2+ influx and a subsequent enhancement of intracellular calcium concentration ([Ca2+]i. Thapsigargin-induced elevation of [Ca2+]i was inhibited by cytochrome P-450 inhibitors and by cytochrome P-450 epoxygenase inhibitor and was reverted by 11,12 EET addition. However, cyclooxygenase and lipoxygenase inhibitors have no effect. Moreover, we observed that four EETs were able to induce 45Ca2+ influx. Finally, we reported that the effect of 11,12 EET on 45Ca2+ influx was sensible to receptor-operated Ca2+ channel blockers (NiCl2, LaCl3) but not to voltage-dependent Ca2+ channel blocker as verapamil. Thus, AA released by Ca2+-independent phospholipase A2 and AA metabolism through cytochrome P-450 pathway may be crucial molecular determinant in thapsigargin activation of SOC channels and store-operated Ca2+ entry pathway in 3T6 fibroblasts. Moreover, EETs, the main cytochrome P-450 epoxygenase metabolites of AA, are involved in thapsigargin-stimulated Ca2+ influx. In summary, our results suggest that EETs are components of calcium influx factor(s).
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Affiliation(s)
- Javier Martínez
- Department of Physiology, Faculty of Pharmacy, Barcelona University, Avda. Joan XXIII s/n, E-08028 Barcelona, Spain
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17
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Abstract
In electrically nonexcitable cells, Ca2+influx is essential for regulating a host of kinetically distinct processes involving exocytosis, enzyme control, gene regulation, cell growth and proliferation, and apoptosis. The major Ca2+entry pathway in these cells is the store-operated one, in which the emptying of intracellular Ca2+stores activates Ca2+influx (store-operated Ca2+entry, or capacitative Ca2+entry). Several biophysically distinct store-operated currents have been reported, but the best characterized is the Ca2+release-activated Ca2+current, ICRAC. Although it was initially considered to function only in nonexcitable cells, growing evidence now points towards a central role for ICRAC-like currents in excitable cells too. In spite of intense research, the signal that relays the store Ca2+content to CRAC channels in the plasma membrane, as well as the molecular identity of the Ca2+sensor within the stores, remains elusive. Resolution of these issues would be greatly helped by the identification of the CRAC channel gene. In some systems, evidence suggests that store-operated channels might be related to TRP homologs, although no consensus has yet been reached. Better understood are mechanisms that inactivate store-operated entry and hence control the overall duration of Ca2+entry. Recent work has revealed a central role for mitochondria in the regulation of ICRAC, and this is particularly prominent under physiological conditions. ICRACtherefore represents a dynamic interplay between endoplasmic reticulum, mitochondria, and plasma membrane. In this review, we describe the key electrophysiological features of ICRACand other store-operated Ca2+currents and how they are regulated, and we consider recent advances that have shed insight into the molecular mechanisms involved in this ubiquitous and vital Ca2+entry pathway.
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Affiliation(s)
- Anant B Parekh
- Department of Physiology, University of Oxford, United Kingdom.
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18
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Moreau B, Straube S, Fisher RJ, Putney JW, Parekh AB. Ca2+-calmodulin-dependent facilitation and Ca2+ inactivation of Ca2+ release-activated Ca2+ channels. J Biol Chem 2004; 280:8776-83. [PMID: 15611075 DOI: 10.1074/jbc.m409619200] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In non-excitable cells, one major route for Ca2+ influx is through store-operated Ca2+ channels in the plasma membrane. These channels are activated by the emptying of intracellular Ca2+ stores, and in some cell types store-operated influx occurs through Ca2+ release-activated Ca2+ (CRAC) channels. Here, we report that intracellular Ca2+ modulates CRAC channel activity through both positive and negative feedback steps in RBL-1 cells. Under conditions in which cytoplasmic Ca2+ concentration can fluctuate freely, we find that store-operated Ca2+ entry is impaired either following overexpression of a dominant negative calmodulin mutant or following whole-cell dialysis with a calmodulin inhibitory peptide. The peptide had no inhibitory effect when intracellular Ca2+ was buffered strongly at low levels. Hence, Ca2+-calmodulin is not required for the activation of CRAC channels per se but is an important regulator under physiological conditions. We also find that the plasma membrane Ca2+ATPase is the dominant Ca2+ efflux pathway in these cells. Although the activity of the Ca2+ pump is regulated by calmodulin, the store-operated Ca2+ entry is more sensitive to inhibition by the calmodulin mutant than by Ca2+ extrusion. Hence, these two plasmalemmal Ca2+ transport systems may differ in their sensitivities to endogenous calmodulin. Following the activation of Ca2+ entry, the rise in intracellular Ca2+ subsequently feeds back to further inhibit Ca2+ influx. This slow inactivation can be activated by a relatively brief Ca2+ influx (30-60 s); it reverses slowly and is not altered by overexpression of the calmodulin mutant. Hence, the same messenger, intracellular Ca2+, can both facilitate and inactivate Ca2+ entry through store-operated CRAC channels and through different mechanisms.
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Affiliation(s)
- Ben Moreau
- Laboratory of Cellular and Molecular Signalling, Department of Physiology, University of Oxford, Parks Road, Oxford OX1 3PT, United Kingdom
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19
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Narenjkar J, Marsh SJ, Assem ESK. Inhibition of the antigen-induced activation of RBL-2H3 cells by charybdotoxin and cetiedil. Eur J Pharmacol 2004; 483:95-106. [PMID: 14729096 DOI: 10.1016/j.ejphar.2003.10.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Quinidine and Ba(2+), non-selective K(+)-channel blockers, have previously been shown to inhibit antigen-induced mediator (beta-hexosaminidase) release from RBL-2H3 cells, a mucosal-type mast cell line. We therefore used selective blockers of Ca(2+)-activated and other K(+) channels to determine if there was a role for these channels in antigen-induced mediator release. Charybdotoxin and cetiedil dose-dependently inhibited beta-hexosaminidase release with IC(50) values of 133 nM and 84 microM, respectively. Charybdotoxin also inhibited the repolarization phase of the antigen-induced biphasic change in the membrane potential (IC(50) 84 nM), antigen-stimulated 86Rb(+)-efflux and increase in free intracellular calcium, [Ca(2+)](i). Iberiotoxin, margatoxin, apamin and tetraethylammonium had no effect on beta-hexosaminidase release. These results suggest that K(+) conductances play a significant role in mediator release from RBL-2H3, that these conductances are of the intermediate conductance Ca(2+)-activated K(+) channel (IK(Ca)) type, and that they are somewhat similar to those which have been described in red blood cells, though they are much less sensitive to clotrimazole.
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Affiliation(s)
- Jamshid Narenjkar
- Department of Pharmacology, University College London, Gower St., London WC1E 6BT, UK
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20
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Narenjkar J, Assem ESK, Ganellin CR. Inhibition of the antigen-induced activation of RBL-2H3 cells by cetiedil and some of its analogues. Eur J Pharmacol 2004; 483:107-16. [PMID: 14729097 DOI: 10.1016/j.ejphar.2003.10.014] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Our previous studies on rat basophilic leukaemia (RBL-2H3) cells suggested that IK(Ca) channels similar to those in red blood cells (RBC) may be involved in the antigen-induced beta-hexosaminidase release. Since cetiedil blocks these channels in both cell types, we studied the inhibition by a selection of the synthetic analogues of cetiedil (UCL compounds) of antigen-induced beta-hexosaminidase release and 86Rb(+)-efflux from RBL-2H3 cells. We tested the (+)- and (-)-enantiomers of cetiedil (UCL 1348 and UCL 1349), the more lipophilic triphenylacetic acid derivatives (UCL 1495 and UCL 1617) and (9-benzyl-fluoren)-9-yl derivatives (UCL 1608 and UCL 1710). They all inhibited antigen-induced beta-hexosaminidase release and 86Rb(+)-efflux. Their relative potency in inhibiting antigen-induced beta-hexosaminidase release was UCL 1608>1710>1617>1348>1349>1495, with IC(50) values of 9.6+/-0.6, 14.4+/-2.2, 23.4+/-1.4, 29.8+/-1.1, 77.5+/-11.8 and 104.6+/-14.7 (microM), respectively. These IC(50)s suggest some dissimilarity between IK(Ca) in RBL-2H3 cells and RBC. Lipophilicity and potency were well correlated in RBC, but not in RBL-2H3 cells.
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Affiliation(s)
- Jamshid Narenjkar
- Department of Pharmacology, University College London, Gower St., London WC1E 6BT, UK
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21
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Malli R, Frieden M, Osibow K, Zoratti C, Mayer M, Demaurex N, Graier WF. Sustained Ca2+ transfer across mitochondria is Essential for mitochondrial Ca2+ buffering, sore-operated Ca2+ entry, and Ca2+ store refilling. J Biol Chem 2003; 278:44769-79. [PMID: 12941956 DOI: 10.1074/jbc.m302511200] [Citation(s) in RCA: 154] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mitochondria have been found to sequester and release Ca2+ during cell stimulation with inositol 1,4,5-triphosphate-generating agonists, thereby generating subplasmalemmal microdomains of low Ca2+ that sustain activity of capacitative Ca2+ entry (CCE). Procedures that prevent mitochondrial Ca2+ uptake inhibit local Ca2+ buffering and CCE, but it is not clear whether Ca2+ has to transit through or remains trapped in the mitochondria. Thus, we analyzed the contribution of mitochondrial Ca2+ efflux on the ability of mitochondria to buffer subplasmalemmal Ca2+, to maintain CCE, and to facilitate endoplasmic reticulum (ER) refilling in endothelial cells. Upon the addition of histamine, the initial mitochondrial Ca2+ transient, monitored with ratio-metric-pericam-mitochondria, was largely independent of extracellular Ca2+. However, subsequent removal of extracellular Ca2+ produced a reversible decrease in [Ca2+]mito, indicating that Ca2+ was continuously taken up and released by mitochondria, although [Ca2+]mito had returned to basal levels. Accordingly, inhibition of the mitochondrial Na+/Ca2+ exchanger with CGP 37157 increased [Ca2+]mito and abolished the ability of mitochondria to buffer subplasmalemmal Ca2+, resulting in an increased activity of BKCa channels and a decrease in CCE. Hence, CGP 37157 also reversibly inhibited ER refilling during cell stimulation. These effects of CGP 37157 were mimicked if mitochondrial Ca2+ uptake was prevented with oligomycin/antimycin A. Thus, during cell stimulation a continuous Ca2+ flux through mitochondria underlies the ability of mitochondria to generate subplasmalemmal microdomains of low Ca2+, to facilitate CCE, and to relay Ca2+ from the plasma membrane to the ER.
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Affiliation(s)
- Roland Malli
- Department of Medical Biochemistry and Medical Molecular Biology, University of Graz, 8010 Graz, Austria
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22
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Smani T, Zakharov SI, Leno E, Csutora P, Trepakova ES, Bolotina VM. Ca2+-independent phospholipase A2 is a novel determinant of store-operated Ca2+ entry. J Biol Chem 2003; 278:11909-15. [PMID: 12547829 DOI: 10.1074/jbc.m210878200] [Citation(s) in RCA: 101] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Store-operated cation (SOC) channels and capacitative Ca(2+) entry (CCE) play very important role in cellular function, but the mechanism of their activation remains one of the most intriguing and long lasting mysteries in the field of Ca(2+) signaling. Here, we present the first evidence that Ca(2+)-independent phospholipase A(2) (iPLA(2)) is a crucial molecular determinant in activation of SOC channels and store-operated Ca(2+) entry pathway. Using molecular, imaging, and electrophysiological techniques, we show that directed molecular or pharmacological impairment of the functional activity of iPLA(2) leads to irreversible inhibition of CCE mediated by nonselective SOC channels and by Ca(2+)-release-activated Ca(2+) (CRAC) channels. Transfection of vascular smooth muscle cells (SMC) with antisense, but not sense, oligonucleotides for iPLA(2) impaired thapsigargin (TG)-induced activation of iPLA(2) and TG-induced Ca(2+) and Mn(2+) influx. Identical inhibition of TG-induced Ca(2+) and Mn(2+) influx (but not Ca(2+) release) was observed in SMC, human platelets, and Jurkat T-lymphocytes when functional activity of iPLA(2) was inhibited by its mechanism-based suicidal substrate, bromoenol lactone (BEL). Moreover, irreversible inhibition of iPLA(2) impaired TG-induced activation of single nonselective SOC channels in SMC and BAPTA (1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid)-induced activation of whole-cell CRAC current in rat basophilic leukemia cells. Thus, functional iPLA(2) is required for activation of store-operated channels and capacitative Ca(2+) influx in wide variety of cell types.
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Affiliation(s)
- Tarik Smani
- Boston University School of Medicine, Boston, Massachusetts 02118, USA
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23
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Esenabhalu VE, Schaeffer G, Graier WF. Free fatty acid overload attenuates Ca2+ signaling and NO production in endothelial cells. Antioxid Redox Signal 2003; 5:147-53. [PMID: 12716474 DOI: 10.1089/152308603764816505] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Hyperlipidemia represents a major risk factor for development of vascular dysfunction and atherosclerosis. Although the unfortunate role of low-density lipoprotein has been clearly demonstrated, the mechanistic pathways through which triglyceride-derived free fatty acids (FFAs) contribute to vascular disorders are not completely understood. Thus, the present study was designed to elucidate the effects of FFAs on cultured endothelial cells. The Ca(2+) signaling, endothelial nitric oxide synthase (eNOS) activity, and production of superoxide anions (.O(2)(-)) were monitored in cells treated with bovine serum albumin-conjugated FFA. FFA-loaded cells showed enhanced intracellular Ca(2+) release in response to ATP, histamine, or the SERCA inhibitor thapsigargin. This effect corresponded to an overall increase in intracellularly stored Ca(2+). In contrast, autacoid-triggered elevation of cytosolic free Ca(2+) concentration was blunted in FFA-loaded cells due to inhibition of capacitative Ca(2+) entry. In agreement with the reduced Ca(2+) signaling, the Ca(2+)-dependent activity of eNOS was reduced under basal conditions and if cells were stimulated with ATP, histamine, or thapsigargin. The attenuated eNOS activity was associated with.O(2)(-) release in FFA-loaded cells. These data indicate that FFAs significantly affect endothelial Ca(2+) signaling, eNOS activity, and.O(2)(-) release and, thus, might contribute to vascular dysfunction in atherogenesis.
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Affiliation(s)
- Victor E Esenabhalu
- Department of Medical Biochemistry and Medical Molecular Biology, Karl-Franzens University of Graz, Harrachgasse 21/211, A-8010 Graz, Austria
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24
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Parekh AB. Store-operated Ca2+ entry: dynamic interplay between endoplasmic reticulum, mitochondria and plasma membrane. J Physiol 2003; 547:333-48. [PMID: 12576497 PMCID: PMC2342659 DOI: 10.1113/jphysiol.2002.034140] [Citation(s) in RCA: 158] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
In eukaryotic cells, hormones and neurotransmitters that engage the phosphoinositide pathway evoke a biphasic increase in intracellular free Ca2+ concentration: an initial transient release of Ca2+ from intracellular stores is followed by a sustained phase of Ca2+ influx. This influx is generally store-dependent and is required for controlling a host of Ca2+-dependent processes ranging from exocytosis to cell growth and proliferation. In many cell types, store-operated Ca2+ entry is manifest as a non-voltage-gated Ca2+ current called ICRAC (Ca2+ release-activated Ca2+ current). Just how store emptying activates CRAC channels remains unclear, and some of our recent experiments that address this issue will be described. No less important from a physiological perspective is the weak Ca2+ buffer paradox: whereas macroscopic (whole cell) ICRAC can be measured routinely in the presence of strong intracellular Ca2+ buffer, the current is generally not detectable under physiological conditions of weak buffering following store emptying with the second messenger InsP3. In this review, I describe some of our experiments aimed at understanding just why InsP3 is ineffective under these conditions and which lead us to conclude that respiring mitochondria are essential for the activation of ICRAC in weak intracellular Ca2+ buffer. Mitochondrial Ca2+ uptake also increases the dynamic range over which InsP3 functions as the second messenger that controls Ca2+ influx. Finally, we find that Ca2+-dependent slow inactivation of Ca2+ influx, a widespread but poorly understood phenomenon that helps shape the profile of an intracellular Ca2+ signal, is regulated by mitochondrial Ca2+ buffering. Thus, by enabling macroscopic store-operated Ca2+ current to activate and then by controlling its extent and duration, mitochondria play a crucial role in all stages of store-operated Ca2+ influx. Store-operated Ca2+ entry reflects therefore a dynamic interplay between endoplasmic reticulum, mitochondria and plasma membrane.
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Affiliation(s)
- Anant B Parekh
- Department of Physiology, University of Oxford, Parks Road, Oxford OX1 3PT, UK.
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25
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Abstract
Ca(2+) enters cells through an assortment of Ca(2+)-permeable channels that respond to different stimuli and couple to different cellular responses. Several different Ca(2+) entry pathways can be activated by receptors that stimulate phospholipase C (PLC). Both limbs of this signaling pathway (IP(3) and diacylglycerol), PLC itself, and its substrate (PIP(2)) contribute to the coordinate regulation of these Ca(2+) entry pathways.
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Affiliation(s)
- Colin W Taylor
- Department of Pharmacology, Tennis Court Road, CB2 1PD, Cambridge, United Kingdom.
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26
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Venkatachalam K, van Rossum DB, Patterson RL, Ma HT, Gill DL. The cellular and molecular basis of store-operated calcium entry. Nat Cell Biol 2002; 4:E263-72. [PMID: 12415286 DOI: 10.1038/ncb1102-e263] [Citation(s) in RCA: 306] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The impact of calcium signalling on so many areas of cell biology reflects the crucial role of calcium signals in the control of diverse cellular functions. Despite the precision with which spatial and temporal details of calcium signals have been resolved, a fundamental aspect of the generation of calcium signals -- the activation of 'store-operated channels' (SOCs) -- remains a molecular and mechanistic mystery. Here we review new insights into the exchange of signals between the endoplasmic reticulum (ER) and plasma membrane that result in activation of calcium entry channels mediating crucial long-term calcium signals.
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Affiliation(s)
- Kartik Venkatachalam
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
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