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Berna-Erro A, Sanchez-Collado J, Nieto-Felipe J, Macias-Diaz A, Redondo PC, Smani T, Lopez JJ, Jardin I, Rosado JA. The Ca 2+ Sensor STIM in Human Diseases. Biomolecules 2023; 13:1284. [PMID: 37759684 PMCID: PMC10526185 DOI: 10.3390/biom13091284] [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: 07/14/2023] [Revised: 08/11/2023] [Accepted: 08/20/2023] [Indexed: 09/29/2023] Open
Abstract
The STIM family of proteins plays a crucial role in a plethora of cellular functions through the regulation of store-operated Ca2+ entry (SOCE) and, thus, intracellular calcium homeostasis. The two members of the mammalian STIM family, STIM1 and STIM2, are transmembrane proteins that act as Ca2+ sensors in the endoplasmic reticulum (ER) and, upon Ca2+ store discharge, interact with and activate the Orai/CRACs in the plasma membrane. Dysregulation of Ca2+ signaling leads to the pathogenesis of a variety of human diseases, including neurodegenerative disorders, cardiovascular diseases, cancer, and immune disorders. Therefore, understanding the mechanisms underlying Ca2+ signaling pathways is crucial for developing therapeutic strategies targeting these diseases. This review focuses on several rare conditions associated with STIM1 mutations that lead to either gain- or loss-of-function, characterized by myopathy, hematological and immunological disorders, among others, and due to abnormal activation of CRACs. In addition, we summarize the current evidence concerning STIM2 allele duplication and deletion associated with language, intellectual, and developmental delay, recurrent pulmonary infections, microcephaly, facial dimorphism, limb anomalies, hypogonadism, and congenital heart defects.
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Affiliation(s)
- Alejandro Berna-Erro
- Department of Physiology, Institute of Molecular Pathology Biomarkers, Universidad de Extremadura, 10003 Caceres, Spain; (A.B.-E.); (J.N.-F.); (A.M.-D.); (P.C.R.); (J.J.L.)
| | - Jose Sanchez-Collado
- Department of Medical Physiology and Biophysics, University of Seville, 41004 Seville, Spain; (J.S.-C.); (T.S.)
| | - Joel Nieto-Felipe
- Department of Physiology, Institute of Molecular Pathology Biomarkers, Universidad de Extremadura, 10003 Caceres, Spain; (A.B.-E.); (J.N.-F.); (A.M.-D.); (P.C.R.); (J.J.L.)
| | - Alvaro Macias-Diaz
- Department of Physiology, Institute of Molecular Pathology Biomarkers, Universidad de Extremadura, 10003 Caceres, Spain; (A.B.-E.); (J.N.-F.); (A.M.-D.); (P.C.R.); (J.J.L.)
| | - Pedro C. Redondo
- Department of Physiology, Institute of Molecular Pathology Biomarkers, Universidad de Extremadura, 10003 Caceres, Spain; (A.B.-E.); (J.N.-F.); (A.M.-D.); (P.C.R.); (J.J.L.)
| | - Tarik Smani
- Department of Medical Physiology and Biophysics, University of Seville, 41004 Seville, Spain; (J.S.-C.); (T.S.)
- Group of Cardiovascular Pathophysiology, Institute of Biomedicine of Seville, University Hospital of Virgen del Rocio, University of Seville, Spanish National Research Council (CSIC), 41004 Seville, Spain
| | - Jose J. Lopez
- Department of Physiology, Institute of Molecular Pathology Biomarkers, Universidad de Extremadura, 10003 Caceres, Spain; (A.B.-E.); (J.N.-F.); (A.M.-D.); (P.C.R.); (J.J.L.)
| | - Isaac Jardin
- Department of Physiology, Institute of Molecular Pathology Biomarkers, Universidad de Extremadura, 10003 Caceres, Spain; (A.B.-E.); (J.N.-F.); (A.M.-D.); (P.C.R.); (J.J.L.)
| | - Juan A. Rosado
- Department of Physiology, Institute of Molecular Pathology Biomarkers, Universidad de Extremadura, 10003 Caceres, Spain; (A.B.-E.); (J.N.-F.); (A.M.-D.); (P.C.R.); (J.J.L.)
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The Molecular Heterogeneity of Store-Operated Ca 2+ Entry in Vascular Endothelial Cells: The Different roles of Orai1 and TRPC1/TRPC4 Channels in the Transition from Ca 2+-Selective to Non-Selective Cation Currents. Int J Mol Sci 2023; 24:ijms24043259. [PMID: 36834672 PMCID: PMC9967124 DOI: 10.3390/ijms24043259] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Revised: 01/31/2023] [Accepted: 02/03/2023] [Indexed: 02/11/2023] Open
Abstract
Store-operated Ca2+ entry (SOCE) is activated in response to the inositol-1,4,5-trisphosphate (InsP3)-dependent depletion of the endoplasmic reticulum (ER) Ca2+ store and represents a ubiquitous mode of Ca2+ influx. In vascular endothelial cells, SOCE regulates a plethora of functions that maintain cardiovascular homeostasis, such as angiogenesis, vascular tone, vascular permeability, platelet aggregation, and monocyte adhesion. The molecular mechanisms responsible for SOCE activation in vascular endothelial cells have engendered a long-lasting controversy. Traditionally, it has been assumed that the endothelial SOCE is mediated by two distinct ion channel signalplexes, i.e., STIM1/Orai1 and STIM1/Transient Receptor Potential Canonical 1(TRPC1)/TRPC4. However, recent evidence has shown that Orai1 can assemble with TRPC1 and TRPC4 to form a non-selective cation channel with intermediate electrophysiological features. Herein, we aim at bringing order to the distinct mechanisms that mediate endothelial SOCE in the vascular tree from multiple species (e.g., human, mouse, rat, and bovine). We propose that three distinct currents can mediate SOCE in vascular endothelial cells: (1) the Ca2+-selective Ca2+-release activated Ca2+ current (ICRAC), which is mediated by STIM1 and Orai1; (2) the store-operated non-selective current (ISOC), which is mediated by STIM1, TRPC1, and TRPC4; and (3) the moderately Ca2+-selective, ICRAC-like current, which is mediated by STIM1, TRPC1, TRPC4, and Orai1.
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Liang X, Zhang N, Pan H, Xie J, Han W. Development of Store-Operated Calcium Entry-Targeted Compounds in Cancer. Front Pharmacol 2021; 12:688244. [PMID: 34122115 PMCID: PMC8194303 DOI: 10.3389/fphar.2021.688244] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Accepted: 05/17/2021] [Indexed: 11/17/2022] Open
Abstract
Store-operated Ca2+ entry (SOCE) is the major pathway of Ca2+ entry in mammalian cells, and regulates a variety of cellular functions including proliferation, motility, apoptosis, and death. Accumulating evidence has indicated that augmented SOCE is related to the generation and development of cancer, including tumor formation, proliferation, angiogenesis, metastasis, and antitumor immunity. Therefore, the development of compounds targeting SOCE has been proposed as a potential and effective strategy for use in cancer therapy. In this review, we summarize the current research on SOCE inhibitors and blockers, discuss their effects and possible mechanisms of action in cancer therapy, and induce a new perspective on the treatment of cancer.
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Affiliation(s)
- Xiaojing Liang
- Department of Medical Oncology, Sir Run Run Shaw Hospital, College of Medicine, Zhejiang University, Hangzhou, China
| | - Ningxia Zhang
- Department of Medical Oncology, Sir Run Run Shaw Hospital, College of Medicine, Zhejiang University, Hangzhou, China
| | - Hongming Pan
- Department of Medical Oncology, Sir Run Run Shaw Hospital, College of Medicine, Zhejiang University, Hangzhou, China
| | - Jiansheng Xie
- Department of Medical Oncology, Sir Run Run Shaw Hospital, College of Medicine, Zhejiang University, Hangzhou, China.,Laboratory of Cancer Biology, Institute of Clinical Science, Sir Run Run Shaw Hospital, College of Medicine, Zhejiang University, Hangzhou, China
| | - Weidong Han
- Department of Medical Oncology, Sir Run Run Shaw Hospital, College of Medicine, Zhejiang University, Hangzhou, China
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4
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Derler I, Fritsch R, Schindl R, Romanin C. CRAC inhibitors: identification and potential. Expert Opin Drug Discov 2013; 3:787-800. [PMID: 23496221 DOI: 10.1517/17460441.3.7.787] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
BACKGROUND Ca(2+) release-activated Ca(2+) (CRAC) channels, a subfamily of store-operated channels, play an essential role in various diseases such as immune disorders and allergic responses. OBJECTIVE The successful treatment of these diseases requires the identification of specific inhibitors. So far, a variety of chemical compounds blocking CRAC have been identified; however, they have all turned out to be less specific. Recently two proteins, STIM1 and ORAI1, have been identified as the essential components that fully reconstitute CRAC currents with a similar biophysical fingerprint. METHOD These two proteins and their activation process represent direct targets for the application of specific CRAC inhibitors. RESULTS/CONCLUSION For drug development, fluorescence microscopy adaptable for high-throughput screening will provide a powerful assay to mechanistically identify potential CRAC inhibitors that act on various stages within the STIM1/ORAI1 activation pathway visualized by fluorescent-tagged proteins.
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Affiliation(s)
- Isabella Derler
- University of Linz, Institute of Biophysics, A-4040 Linz, Austria +43 732 2468 9272 ; +43 732 2468 9280 ; ;
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Derler I, Schindl R, Fritsch R, Heftberger P, Riedl MC, Begg M, House D, Romanin C. The action of selective CRAC channel blockers is affected by the Orai pore geometry. Cell Calcium 2012; 53:139-51. [PMID: 23218667 PMCID: PMC3580291 DOI: 10.1016/j.ceca.2012.11.005] [Citation(s) in RCA: 109] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2012] [Revised: 11/02/2012] [Accepted: 11/03/2012] [Indexed: 11/10/2022]
Abstract
As the molecular composition of calcium-release activated calcium (CRAC) channels has been unknown for two decades, elucidation of selective inhibitors has been considerably hampered. By the identification of the two key components of CRAC channels, STIM1 and Orai1 have emerged as promising targets for CRAC blockers. The aim of this study was to thoroughly characterize the effects of two selective CRAC channel blockers on currents derived from STIM1/Orai heterologoulsy expressed in HEK293 cells. The novel compounds GSK-7975A and GSK-5503A were tested for effects on STIM1 mediated Orai1 or Orai3 currents by whole-cell patch-clamp recordings and for the effects on STIM1 oligomerisation or STIM1/Orai coupling by FRET microscopy. To investigate their site of action, inhibitory effects of these molecules were explored using Orai pore mutants. The GSK blockers inhibited Orai1 and Orai3 currents with an IC50 of approximately 4 μM and exhibited a substantially slower rate of onset than the typical pore blocker La3+, together with almost no current recovery upon wash-out over 4 min. For the less Ca2+-selective Orai1 E106D pore mutant, ICRAC inhibition was significantly reduced. FRET experiments indicated that neither STIM1–STIM1 oligomerization nor STIM1–Orai1 coupling was affected by these compounds. These CRAC channel blockers are acting downstream of STIM1 oligomerization and STIM1/Orai1 interaction, potentially via an allosteric effect on the selectivity filter of Orai. The elucidation of these CRAC current blockers represents a significant step toward the identification of CRAC channel-selective drug compounds.
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Affiliation(s)
- Isabella Derler
- Institute of Biophysics, University of Linz, 4040 Linz, Austria
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6
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Orai1 calcium channels in the vasculature. Pflugers Arch 2012; 463:635-47. [PMID: 22402985 PMCID: PMC3323825 DOI: 10.1007/s00424-012-1090-2] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2012] [Revised: 02/21/2012] [Accepted: 02/21/2012] [Indexed: 10/28/2022]
Abstract
Orai1 was discovered in T cells as a calcium-selective channel that is activated by store depletion. Recent studies suggest that it is expressed and functionally important also in blood vessels, not only because haematopoietic cells can incorporate in the vascular wall but also because Orai1 is expressed and functional in vascular smooth muscle cells and endothelial cells. This article summarises the arising observations in this new area of vascular research and debates underlying issues and challenges for future investigations. The primary focus is on vascular smooth muscle cells and endothelial cells. Specific topics include Orai1 expression; Orai1 roles in store-operated calcium entry and ionic currents of store-depleted cells; blockade of Orai1-related signals by Synta 66 and other pharmacology; activation or regulation of Orai1-related signals by physiological substances and compartments; stromal interaction molecules and the relationship of Orai1 to other ion channels, transporters and pumps; transient receptor potential canonical channels and their contribution to store-operated calcium entry; roles of Orai1 in vascular tone, remodelling, thrombus formation and inflammation; and Orai2 and Orai3. Overall, the observations suggest the existence of an additional, previously unrecognised, calcium channel of the vascular wall that is functionally important particularly in remodelling but probably also in certain vasoconstrictor contexts.
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7
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Sweeney Z, Minatti A, Button D, Patrick S. Small-Molecule Inhibitors of Store-Operated Calcium Entry. ChemMedChem 2009; 4:706-18. [DOI: 10.1002/cmdc.200800452] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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8
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Dawson NS, Zawieja DC, Wu MH, Granger HJ. Signaling pathways mediating VEGF165-induced calcium transients and membrane depolarization in human endothelial cells. FASEB J 2006; 20:991-3. [PMID: 16581961 DOI: 10.1096/fj.05-3923fje] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Cytosolic calcium and membrane potential were monitored simultaneously in quiescent human umbilical vein endothelial cells (HUVEC) exposed to vascular endothelial growth factor (VEGF)165 using the fluorescent indicators indo-1 AM and DiSBAC2(3), respectively. Application of VEGF165 to cells elicits a rapid rise in cytosolic calcium followed by a slower decline toward control values. Peak calcium is associated with a slight membrane hyperpolarization; however, as calcium falls toward control, a strong depolarization develops and is sustained throughout a 10-min period of VEGF165 stimulation. Both the VEGF165-mediated rise in cytosolic calcium and membrane depolarization are eliminated by inhibitors of VEGFR-2, tyrosine kinase, src kinase and inositol-1,4,5 triphosphate-operated calcium channels. Calcium entry, which is initially facilitated by transient hyperpolarization, is restricted by a substantial, sustained depolarization that developed during the downstroke of the calcium spike. Inhibition of plasmalemmal calcium channels diminished the magnitude and duration of the calcium spike, suggesting that extracellular calcium influx, secondary to stores release, is a significant component of the calcium transient. Inhibition of chloride channels substantially reduced membrane depolarization. In addition, the depolarization is modulated by PI3 kinase in a ras-independent manner. In summary, intracellular calcium and membrane potential are influenced by several key signaling cascades of VEGFR-2 activation in HUVEC.
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Affiliation(s)
- Nancy S Dawson
- Cardiovascular Research Institute and Department of Medical Physiology, College of Medicine, Texas A&M University System Health Science Center, College Station, Texas 77843-1114, USA
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9
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Lemonnier L, Prevarskaya N, Mazurier J, Shuba Y, Skryma R. 2-APB inhibits volume-regulated anion channels independently from intracellular calcium signaling modulation. FEBS Lett 2003; 556:121-6. [PMID: 14706838 DOI: 10.1016/s0014-5793(03)01387-5] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
It has previously been suggested that volume-regulated anion channels (VRACs) and store-operated channels (SOCs) interact with each other according to their expected colocalization in the plasma membrane of LNCaP cells. In order to study interactions between these two channels, we used 2-aminoethoxydiphenyl borate (2-APB) as a regular SOC inhibitor. Surprisingly 2-APB reduced VRAC activity in a dose-dependent manner (IC(50)=122.8 microM), but not 2,2-diphenyltetrahydrofuran (a structural analog of 2-APB). This effect was also present in keratinocytes. We conclude that 2-APB is an inhibitor of the VRAC family, and is also a potent tool to study the SOC-VRAC interaction in LNCaP cells.
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Affiliation(s)
- L Lemonnier
- Laboratoire de Physiologie Cellulaire, INSERM EMI 0228, Bâtiment SN3, USTL, 59655, Villeneuve d'Ascq, France
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10
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Abstract
Endothelial cells (EC) form a unique signal-transducing surface in the vascular system. The abundance of ion channels in the plasma membrane of these nonexcitable cells has raised questions about their functional role. This review presents evidence for the involvement of ion channels in endothelial cell functions controlled by intracellular Ca(2+) signals, such as the production and release of many vasoactive factors, e.g., nitric oxide and PGI(2). In addition, ion channels may be involved in the regulation of the traffic of macromolecules by endocytosis, transcytosis, the biosynthetic-secretory pathway, and exocytosis, e.g., tissue factor pathway inhibitor, von Willebrand factor, and tissue plasminogen activator. Ion channels are also involved in controlling intercellular permeability, EC proliferation, and angiogenesis. These functions are supported or triggered via ion channels, which either provide Ca(2+)-entry pathways or stabilize the driving force for Ca(2+) influx through these pathways. These Ca(2+)-entry pathways comprise agonist-activated nonselective Ca(2+)-permeable cation channels, cyclic nucleotide-activated nonselective cation channels, and store-operated Ca(2+) channels or capacitative Ca(2+) entry. At least some of these channels appear to be expressed by genes of the trp family. The driving force for Ca(2+) entry is mainly controlled by large-conductance Ca(2+)-dependent BK(Ca) channels (slo), inwardly rectifying K(+) channels (Kir2.1), and at least two types of Cl( -) channels, i.e., the Ca(2+)-activated Cl(-) channel and the housekeeping, volume-regulated anion channel (VRAC). In addition to their essential function in Ca(2+) signaling, VRAC channels are multifunctional, operate as a transport pathway for amino acids and organic osmolytes, and are possibly involved in endothelial cell proliferation and angiogenesis. Finally, we have also highlighted the role of ion channels as mechanosensors in EC. Plasmalemmal ion channels may signal rapid changes in hemodynamic forces, such as shear stress and biaxial tensile stress, but also changes in cell shape and cell volume to the cytoskeleton and the intracellular machinery for metabolite traffic and gene expression.
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Affiliation(s)
- B Nilius
- Department of Physiology, KU Leuven, Campus Gasthuisberg, Leuven, Belgium.
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11
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Pocock TM, Williams B, Curry FE, Bates DO. VEGF and ATP act by different mechanisms to increase microvascular permeability and endothelial [Ca(2+)](i). Am J Physiol Heart Circ Physiol 2000; 279:H1625-34. [PMID: 11009449 DOI: 10.1152/ajpheart.2000.279.4.h1625] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Vascular endothelial growth factor (VEGF) increases hydraulic conductivity (L(p)) by stimulating Ca(2+) influx into endothelial cells. To determine whether VEGF-mediated Ca(2+) influx is stimulated by release of Ca(2+) from intracellular stores, we measured the effect of Ca(2+) store depletion on VEGF-mediated increased L(p) and endothelial intracellular Ca(2+) concentration ([Ca(2+)](i)) of frog mesenteric microvessels. Inhibition of Ca(2+) influx by perfusion with NiCl(2) significantly attenuated VEGF-mediated increased [Ca(2+)](i). Depletion of Ca(2+) stores by perfusion of vessels with thapsigargin did not affect the VEGF-mediated increased [Ca(2+)](i) or the increase in L(p). In contrast, ATP-mediated increases in both [Ca(2+)](i) and L(p) were inhibited by thapsigargin perfusion, demonstrating that ATP stimulated store-mediated Ca(2+) influx. VEGF also increased Mn(2+) influx after perfusion with thapsigargin, whereas ATP did not. These data showed that VEGF increased [Ca(2+)](i) and L(p) even when Ca(2+) stores were depleted and under conditions that prevented ATP-mediated increases in [Ca(2+)](i) and L(p). This suggests that VEGF acts through a Ca(2+) store-independent mechanism, whereas ATP acts through Ca(2+) store-mediated Ca(2+) influx.
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Affiliation(s)
- T M Pocock
- Department of Physiology, University of Bristol, Bristol BS2 8EJ, LE2 7LX United Kingdom
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12
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Oonuma H, Nakajima T, Nagata T, Iwasawa K, Wang Y, Hazama H, Morita Y, Yamamoto K, Nagai R, Omata M. Endothelin-1 is a potent activator of nonselective cation currents in human bronchial smooth muscle cells. Am J Respir Cell Mol Biol 2000; 23:213-21. [PMID: 10919988 DOI: 10.1165/ajrcmb.23.2.3868] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
The effects of endothelin (ET)-1 on cultured human bronchial smooth muscle cells (HBSMC) were investigated and compared with those of histamine, using the patch clamp techniques and measurements of intracellular Ca(2+) ([Ca(2+)](i)). Both ET-1 and histamine caused an initial transient elevation of [Ca(2+)](i) by Ca(2+) mobilization, followed by a sustained rise due to Ca(2+) entry. Nicardipine inhibited the sustained phase, but La(3+) abolished it. With low ethyleneglycol-bis-(beta-aminoethyl ether)-N,N'-tetraacetic acid (EGTA) and K(+) internal solutions, both ET-1 and histamine induced a sustained depolarization from approximately -40 to -20 mV. Under voltage clamp conditions, both drugs transiently activated an outward K(+) current at a holding potential of 0 mV. Additionally, with a Cs(+) internal solution, they elicited another transient inward current, frequently followed by current oscillations. These transient currents were blocked by high EGTA or heparin. With high EGTA and Cs(+) internal solutions, both drugs activated a long-lasting inward current. The reversal potential of these agonist-induced currents was approximately 0 mV and was not altered by the replacement of internal or external concentration of Cl(-), suggesting that the inward current was a nonselective cation current (I(cat)). The half-maximal effective concentration to activate I(cat) was 12 nM for ET-1 and 11 microM for histamine. La(3+) and Cd(2+) abolished these agonist-induced I(cat). The effects of ET-1 on [Ca(2+)](i) and I(cat) could be blocked by combined pretreatment with BQ-123 and BQ-788. Sarafotoxin S6c also increased [Ca(2+)](i) and activated I(cat). By polymerase chain reaction of reverse transcribed RNA, we detected both ET-A and ET-B receptor messenger RNA. These results provide the first evidence that ET-1 is a potent activator of I(cat) in HBSMC via ET-A and ET-B receptors, and the activation of I(cat) plays an important role in ET-1-induced Ca(2+) entry in human airways.
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MESH Headings
- Bronchi/cytology
- Bronchi/drug effects
- Bronchi/physiology
- Calcium/metabolism
- Calcium Channel Blockers/pharmacology
- Cations/metabolism
- Dose-Response Relationship, Drug
- Endothelin Receptor Antagonists
- Endothelin-1/pharmacology
- Gene Expression Regulation/drug effects
- Histamine/pharmacology
- Humans
- Ion Channels/drug effects
- Ion Channels/physiology
- Lanthanum/pharmacology
- Membrane Potentials/drug effects
- Muscle, Smooth/cytology
- Muscle, Smooth/drug effects
- Muscle, Smooth/physiology
- Nicardipine/pharmacology
- Oligopeptides/pharmacology
- Peptides, Cyclic/pharmacology
- Piperidines/pharmacology
- RNA, Messenger/drug effects
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Receptor, Endothelin A
- Receptor, Endothelin B
- Receptors, Endothelin/genetics
- Viper Venoms/pharmacology
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Affiliation(s)
- H Oonuma
- Departments of Respiratory Medicine, Cardiovascular Medicine, and Gastroenterology, University of Tokyo, Graduate School of Medicine, Tokyo, Japan
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13
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Li JH, Spence KT, Dargis PG, Christian EP. Properties of Ca(2+) release-activated Ca(2+) channel block by 5-nitro-2-(3-phenylpropylamino)-benzoic acid in Jurkat cells. Eur J Pharmacol 2000; 394:171-9. [PMID: 10771282 DOI: 10.1016/s0014-2999(00)00144-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Ca(2+) release-activated Ca(2+) current (I(crac)) has been previously characterized biophysically in Jurkat lymphocytes and other non-excitable cells, but pharmacology remains poorly developed. The present objective was to delineate with whole cell recording details of the interaction of the chloride channel blocker, 5-nitro-2-(3-phenylpropylamino)-benzoic acid (NPPB), with I(crac) in Jurkat cells. NPPB reversibly inhibited I(crac) in a concentration-dependent manner (IC(50)=5 microM). Kinetics for block and unblock of I(crac) by NPPB indicated a bimolecular interaction. Michaelis-Menten analysis indicated that NPPB interacts competitively with extracellular Ca(2+) permeating the I(crac) pathway. Finally, analysis of the pH dependence of I(crac) block by NPPB revealed a reduction in the apparent affinity during extracellular alkalinization that based on the pK(a) for NPPB, suggested that the neutral form of NPPB blocks the Ca(2+) release-activated Ca(2+) (CRAC) channel. Taken together, our results suggest a direct interaction between NPPB and the CRAC channel, and should help guide insights for developing novel and more selective analogues.
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Affiliation(s)
- J H Li
- Department of CNS Discovery, AstraZeneca Pharmaceuticals, Wilmington, DE 19850-5437, USA
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14
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Kondo I. Protein kinase C potentiates capacitative Ca2+ entry that links to steroidogenesis in bovine adrenocortical cells. JAPANESE JOURNAL OF PHARMACOLOGY 2000; 82:210-7. [PMID: 10887951 DOI: 10.1254/jjp.82.210] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
I investigated the role of protein kinase C (PKC) in regulation of the capacitative Ca2+ entry and steroidogenesis in bovine adrenocortical (BA) cells. Thapsigargin (TG)-treatment depleted intracellular Ca2+ stores followed by induction of Ca2+ influx from the extracellular pool and also increasing of Mn2+ influx as an indicator of divalent cation influx in BA cells. Calphostin C, a PKC inhibitor, inhibited the TG-induced [Ca2+]i elevation dose-dependently (0.1-1 microM) and attenuated Mn2+ entry. Phorbol 12-myristate 13-acetate (PMA), an activator of PKC, potentiated the elevation of [Ca2+]i and enhanced Mn2+ entry by TG treatment. These results suggest that PKC may modulate capacitative Ca2+ entry in BA cells. In the presence of extracellular Ca2+, TG enhanced cortisol production in BA cells. Calphostin C attenuated the TG-induced steroidogenesis dose-dependently (0.25-1 microM). PMA enhanced the steroidogenesis dose-dependently (1-100 nM). These results suggested that PKC may have a modulatory effect on the capacitative Ca2+ entry that links to steroidogenesis in BA cells.
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Affiliation(s)
- I Kondo
- Department of Anesthesiology, Jikei University School of Medicine, Tokyo, Japan
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Abstract
Ion channels in the plasma membrane of vascular muscle cells that form the walls of resistance arteries and arterioles play a central role in the regulation of vascular tone. Current evidence indicates that vascular smooth muscle cells express at least 4 different types of K(+) channels, 1 to 2 types of voltage-gated Ca(2+) channels, >/=2 types of Cl(-) channels, store-operated Ca(+) (SOC) channels, and stretch-activated cation (SAC) channels in their plasma membranes, all of which may be involved in the regulation of vascular tone. Calcium influx through voltage-gated Ca(2+), SOC, and SAC channels provides a major source of activator Ca(2+) used by resistance arteries and arterioles. In addition, K(+) and Cl(-) channels and the Ca(2+) channels mentioned previously all are involved in the determination of the membrane potential of these cells. Membrane potential is a key variable that not only regulates Ca(+2) influx through voltage-gated Ca(2+) channels, but also influences release of Ca(2+) from internal stores and Ca(2+)- sensitivity of the contractile apparatus. By controlling Ca(2+) delivery and membrane potential, ion channels are involved in all aspects of the generation and regulation of vascular tone.
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Affiliation(s)
- W F Jackson
- Department of Biological Sciences, Western Michigan University, Kalamazoo, MI 49008, USA.
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16
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Iwamuro Y, Miwa S, Zhang XF, Minowa T, Enoki T, Okamoto Y, Hasegawa H, Furutani H, Okazawa M, Ishikawa M, Hashimoto N, Masaki T. Activation of three types of voltage-independent Ca2+ channel in A7r5 cells by endothelin-1 as revealed by a novel Ca2+ channel blocker LOE 908. Br J Pharmacol 1999; 126:1107-14. [PMID: 10204997 PMCID: PMC1565887 DOI: 10.1038/sj.bjp.0702416] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
1. We have shown that in addition to voltage-operated Ca2+ channel (VOC), endothelin-1 (ET-1) activates two types of Ca2+-permeable nonselective cation channel (NSCC) in A7r5 cells: its lower concentrations (< or = 1 nM; lower [ET-1]) activate only an SK&F 96365-resistant channel (NSCC-1), whereas its higher concentrations (> or = 10 nM; higher [ET-1]) activate an SK&F 96365-sensitive channel (NSCC-2) as well. 2. We now characterized the effects of a blocker of Ca2+ entry channel LOE 908 on NSCCs and store-operated Ca2+ channel (SOCC) in A7r5 cells, and using two drugs, clarified the involvement of these channels in the ET-1-induced increase in the intracellular free Ca2+ concentrations ([Ca2+]i). Whole-cell recordings and [Ca2+]i monitoring with fluo-3 were used. 3. LOE 908 up to 10 microM had no effect on increases in [Ca2+]i induced by thapsigargin or ionomycin, but SK&F 96365 abolished them. 4. In the cells clamped at -60 mV, both lower and higher [ET-1] induced inward currents with linear iv relationships and the reversal potentials of -15.0 mV. Thapsigargin induced no currents. 5. In the presence of nifedipine, lower [ET-1] induced a sustained increase in [Ca2+]i, whereas higher [ET-1] induced a transient peak and a sustained increase. The sustained increases by lower and higher [ET-1] were abolished by removal of extracellular Ca2+, and they were suppressed by LOE 908 to 0 and 35%, respectively, with the LOE 908-resistant part being abolished by SK&F 96365. 6. These results show that LOE 908 is a blocker of NSCCs without effect on SOCC, and that the increase in [Ca2+]i at lower [ET-1] results from Ca2+ entry through NSCC-1 in addition to VOC, whereas the increase at higher [ET-1] involves NSCC-1, NSCC-2 and SOCC in addition to VOC.
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Affiliation(s)
- Y Iwamuro
- Department of Neurosurgery, Kyoto University Faculty of Medicine, Japan
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17
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Malek AM, Jiang L, Lee I, Sessa WC, Izumo S, Alper SL. Induction of nitric oxide synthase mRNA by shear stress requires intracellular calcium and G-protein signals and is modulated by PI 3 kinase. Biochem Biophys Res Commun 1999; 254:231-42. [PMID: 9920763 DOI: 10.1006/bbrc.1998.9921] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
We have investigated the signaling pathways by which shear stress induces accumulation of endothelial nitric oxide synthase (eNOS) mRNA in bovine aortic endothelial cells (BAEC). Steady laminar fluid shear stress (20 dyn/cm2) induced a time-dependent increase in eNOS mRNA levels that did not require de novo protein synthesis and was in part transcriptional. Shear responsiveness was conferred on a luciferase reporter by a portion of the eNOS gene promoter encoding the 5'-flanking region between nt -1600 and -779. Shear-mediated induction of eNOS mRNA was abolished by chelation of intracellular calcium ([Ca2+]i) with BAPTA-AM, and inhibited by blockade of calcium entry with SKF96535. In contrast, eNOS mRNA upregulation by shear was potentiated by thapsigargin-mediated depletion of Ca2+i stores. Pertussis toxin (PTX) inhibited both the shear-induced elevation in [Ca2+]i and the subsequent increase in eNOS mRNA, implicating a PTX-sensitive G-protein in both responses. Shear-induced upregulation of eNOS mRNA was unaffected by the calmodulin inhibitor W-7 and by the tyrosine kinase inhibitor herbimycin A, suggesting that neither calmodulin nor tyrosine kinases are required. However, eNOS mRNA upregulation was potentiated by the PI 3-kinase inhibitors wortmannin and LY294002, suggesting that PI 3-kinase inhibits the shear response. Although microtubule integrity is required for the shear-induced regulation of endothelin-1 mRNA and the morphological and cytoskeletal responses to flow, neither microtubule dissolution with nocodazole nor microtubule stabilization with taxol altered shear-induced [Ca2+]i elevation or upregulation of eNOS mRNA. In conclusion, shear stress of BAEC increases eNOS transcriptional rate and upregulates eNOS mRNA levels by a process that requires calmodulin-independent [Ca2+]i signaling and a PTX-sensitive G-protein, is inhibited by PI 3-kinase, and is independent of microtubule integrity and tyrosine kinase activity.
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Affiliation(s)
- A M Malek
- Department of Neurosurgery, Brigham & Women's Hospital, Children's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA
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18
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Viana F, de Smedt H, Droogmans G, Nilius B. Calcium signalling through nucleotide receptor P2Y2 in cultured human vascular endothelium. Cell Calcium 1998; 24:117-27. [PMID: 9803312 DOI: 10.1016/s0143-4160(98)90079-3] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Microfluorometric measurements in Fura-2-loaded single cultured human vascular endothelial cells were used to characterize the intracellular calcium [Ca2+]i responses triggered by extracellular application of adenosine 5'-triphosphate (ATP) and other nucleotides. Application of ATP or uridine 5'-triphosphate (UTP) gave rise to dose-dependent elevations of [Ca2+]i in all the cells tested. At saturating concentrations of agonist, the [Ca2+]i response was biphasic, with an early peak and a sustained plateau. Unlike peak responses, the sustained Ca2+ plateau was sensitive to removal of Ca2+ from the external medium. Mn2+ quenching revealed the presence of Ca2+ influx during the agonist-induced calcium plateau. The agonist-evoked calcium plateau was inhibited in a dose-dependent manner by the Cl-channel blocker NPPB, by the divalent cation Ni2+ and by the imidazole antimycotic econazole. Previously, these compounds have been shown to block store-operated Ca2+ entry. The two phases of the agonist-evoked [Ca2+]i response were blocked by the specific phospholipase C inhibitor U-73122 and by intracellular injection of low molecular weight heparin, suggesting the involvement of IP3-sensitive intracellular Ca2+ stores. The pharmacological profile of the response, using different nucleotides and analogues, ATP = UTP > ADP = UDP, and no responses to P2X1 and P2Y1 agonists, suggested the involvement of P2Y2 receptors. The expression of mRNA for the P2Y2 receptor was detected by RT-PCR analysis. These results indicate that P2Y2 receptors linked to intracellular Ca2+ mobilization are present in human vascular endothelial cells. The initial [Ca2+]i mobilization is followed by a phase of elevated [Ca2+]i influx.
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Affiliation(s)
- F Viana
- Katholieke Universiteit Leuven, Laboratorium voor Fysiologie, Belgium.
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19
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Harper JL, Shin Y, Daly JW. Loperamide: a positive modulator for store-operated calcium channels? Proc Natl Acad Sci U S A 1997; 94:14912-7. [PMID: 9405713 PMCID: PMC25137 DOI: 10.1073/pnas.94.26.14912] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The depletion of inositol trisphosphate-sensitive intracellular pools of calcium causes activation of store-operated calcium (SOC) channels. Loperamide at 10-30 microM has no effect on intracellular calcium levels alone, but augments calcium levels in cultured cells when SOC channels have been activated. In HL-60 leukemic cells, the apparent positive modulatory effect of loperamide on SOC channels occurs when these channels have been activated after ATP, thapsigargin, or ionomycin-elicited depletion of calcium from intracellular storage sites. Loperamide has no effect when levels of intracellular calcium are elevated through a mechanism not involving SOC channels by using sphingosine. Loperamide caused augmentation of intracellular calcium levels after activation of SOC channels in NIH 3T3 fibroblasts, astrocytoma 1321N cells, smooth muscle DDT-MF2 cells, RBL-2H3 mast cells, and pituitary GH4C1 cells. Only in astrocytoma cells did loperamide cause an elevation in intracellular calcium in the absence of activation of SOC channels. The augmentation of intracellular calcium elicited by loperamide in cultured cells was dependent on extracellular calcium and was somewhat resistant to agents (SKF 96365, miconazole, clotrimazole, nitrendipine, and trifluoperazine) that in the absence of loperamide effectively blocked SOC channels. It appears that loperamide augments influx of calcium through activated SOC channels.
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Affiliation(s)
- J L Harper
- Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
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20
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Iwasawa K, Nakajima T, Hazama H, Goto A, Shin WS, Toyo-oka T, Omata M. Effects of extracellular pH on receptor-mediated Ca2+ influx in A7r5 rat smooth muscle cells: involvement of two different types of channel. J Physiol 1997; 503 ( Pt 2):237-51. [PMID: 9306269 PMCID: PMC1159859 DOI: 10.1111/j.1469-7793.1997.237bh.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
1. The effects of extracellular pH (pHo) on receptor (vasopressin or endothelin-1)-mediated Ca2- entry and Ca(2+)-permeable channels were investigated in aortic smooth muscle cells (A7r5) from rat embryonic thoracic aorta. Intracellular Ca2+ ([Ca2+]i) was measured using fura-2 AM and whole-cell voltage clamp techniques were employed. 2. Vasopressin and endothelin-1 (100 nM) in the presence of nicardipine (10 microM) evoked a sustained rise in [Ca2+]i due to calcium entry. Extracellular acidosis decreased receptor (vasopressin or endothelin-1)-mediated Ca2+ entry, while extracellular alkalosis potentiated it. 3. Depletion of intracellular Ca2+ stores with thapsigargin (1 microM) also evoked Ca2+ entry activated by emptying of intracellular Ca2+ stores (capacitative Ca2+ entry). Extracellular acidosis decreased this capacitative Ca2+ entry, while extracellular alkalosis potentiated it. 4. Under voltage-clamp conditions with Ca+ internal solution, vasopressin and endothelin-1 activated non-selective cation currents (ICAT). Ba2+ or Ca2+ were also charge carriers of ICAT. Reducing the pHo inhibited ICAT, while increasing pHo potentiated it in a reversible manner. 5. Intracellular pH (pHi) changes did not cause the same marked effects as pHo changes, and a high concentration of Hepes (50 mM) in the patch pipette did not inhibit the effects of pHo on ICAT. 6. Similar results were obtained when ICAT was activated by GTP gamma S (1 mM) applied through the patch pipette, even in the absence of agonists, probably because of direct activation of GTP-binding proteins coupled to the receptors. 7. In cells treated with thapsigargin, addition of Ca2+ to the bath solution induced Ca(2+)-dependent K+ currents activated by capacitative Ca2+ entry. However, no measurable ionic currents activated by capacitative Ca2+ entry (ICRAC) were observed under conditions with Cs+ internal solution and EGTA (5 mM), although vasopressin still activated ICAT. 8. These results suggest that the contractile agonists vasopressin and endothelin-1 evoked Ca2+ entry through two different types of Ca(2+)-permeable channel (ICAT and ICRAC) and pHo affects these channels, which may modulate receptor-mediated Ca2+ influx in A7r5 cells. Thus, pH-induced changes of these channels may play a pathophysiological role in the control of receptor-mediated contractions.
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Affiliation(s)
- K Iwasawa
- Second Department of Internal Medicine, Faculty of Medicine, University of Tokyo, Japan
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21
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Cho JH, Balasubramanyam M, Chernaya G, Gardner JP, Aviv A, Reeves JP, Dargis PG, Christian EP. Oligomycin inhibits store-operated channels by a mechanism independent of its effects on mitochondrial ATP. Biochem J 1997; 324 ( Pt 3):971-80. [PMID: 9210424 PMCID: PMC1218516 DOI: 10.1042/bj3240971] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Inhibitors of mitochondrial oxidative metabolism have been proposed to interfere with Ca2+ influx mediated by store-operated channels (SOC), secondary to their effects on ATP production. We assessed SOC activity by 45Ca2+ influx and fluorimetric measurements of free Ca2+ or Mn2+ quench in thapsigargin-treated Chinese hamster ovary cells and Jurkat T-cells, and additionally by electrophysiological measurements of the Ca2+-release-activated Ca2+ current (Icrac) in Jurkat T-cells. Various mitochondrial antagonists were confirmed to inhibit SOC. However, the following evidence supported the proposal that oligomycin, in particular, exerts an inhibitory effect on SOC in addition to its known actions on mitochondria and Na+-pump activity: (i) the concentrations of oligomycin required to inhibit SOC-mediated Ca2+ influx or Icrac (half-inhibitory concentration approximately 2 microM) were nearly 50-fold higher than the concentrations that blocked mitochondrial ATP production; (ii) the rank order of potency of oligomycins A, B and C for decreasing SOC-mediated Ca2+ influx or Icrac differed from that known for inhibition of mitochondrial function; (iii) oligomycin blocked Icrac under voltage clamp and with intracellular Na+ and K+ concentrations fixed by dialysis from the patch pipette, arguing that the effect was not secondary to membrane polarization or pump activity; and (iv) fixing the cytosolic ATP concentration by dialysis from the patch pipette attenuated rotenone- but not oligomycin-mediated inhibition of Icrac. Oligomycin also blocked volume-activated Cl- currents, a profile common to some other known blockers of SOC that are not known mitochondrial inhibitors. These findings raise the possibility that oligomycin interacts directly with SOC, and thus may extend the known pharmacological profile for this type of Ca2+-influx pathway.
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Affiliation(s)
- J H Cho
- Hypertension Research Program, University of Medicine and Dentistry-New Jersey Medical School, 185 South Orange Avenue, Newark, NJ 07103, USA
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22
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Abstract
The functional impact of ion channels in vascular endothelial cells (ECs) is still a matter of controversy. This review describes different types of ion channels in ECs and their role in electrogenesis, Ca2+ signaling, vessel permeability, cell-cell communication, mechano-sensor functions, and pH and volume regulation. One major function of ion channels in ECs is the control of Ca2+ influx either by a direct modulation of the Ca2+ influx pathway or by indirect modulation of K+ and Cl- channels, thereby clamping the membrane at a sufficiently negative potential to provide the necessary driving force for a sustained Ca2+ influx. We discuss various mechanisms of Ca2+ influx stimulation: those that activate nonselective, Ca(2+)-permeable cation channels or those that activate Ca(2+)-selective channels, exclusively or partially operated by the filling state of intracellular Ca2+ stores. We also describe the role of various Ca(2+)- and shear stress-activated K+ channels and different types of Cl- channels for the regulation of the membrane potential.
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Affiliation(s)
- B Nilius
- Laboratorium voor Fysiologie, KU Leuven, Belgium
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23
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Ikeda M, Ariyoshi H, Kambayashi J, Fujitani K, Shinoki N, Sakon M, Kawasaki T, Monden M. Separate analysis of nuclear and cytosolic Ca2+ concentrations in human umbilical vein endothelial cells. J Cell Biochem 1996; 63:23-36. [PMID: 8891901 DOI: 10.1002/(sici)1097-4644(199610)63:1<23::aid-jcb2>3.0.co;2-1] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Ca2+ concentration inside human umbilical vein endothelial cells was studied separately in cytosol and nucleus by a confocal laser scanning microscopy using fluo-3. The in vivo calibration curve for cytosol and nucleus showed good linearity between fluorescence intensity and Ca2+ concentration in cytosol ([Ca2+]i) and nuclei ([Ca2+]n). After calibration, [Ca2+]n was constantly higher than [Ca2+]i before and after the chelation of extracellular Ca2+ suggesting an active Ca2+ accumulation system on nuclear membrane. [Ca2+]n was also constantly higher than [Ca2+]i after the stimulation of thrombin (0.05 U/ml), FCS (10%), and thapsigargin (Tsg, 1 microM). The temporal change of [Ca2+]n and [Ca2+]i was identical, and [Ca2+]i gradient towards the nucleus and peripheral or central [Ca2+]n rise was observed after these stimulations. From these results, [Ca2+]n is not only regulated by the active Ca2+ accumulation system on nuclear membrane at rest but also the generation of inositol-triphosphate. FCS caused heterogeneous [Ca2+]n or [Ca2+]i rise from cell to cell; single spike or oscillatory change of [Ca2+]n and [Ca2+]i was observed in about 56% of cells, which were completely abolished by the chelation of extracellular Ca2+, suggesting that FCS stimulated [Ca2+]n and [Ca2+]i rise solely depending on Ca2+ influx from extracellular medium. The higher concentration of [Ca2+]n and heterogeneous [Ca2+]n rise may have important roles in nuclear-specific cellular responses.
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Affiliation(s)
- M Ikeda
- Department of Surgery II, Osaka University Medical School, Japan
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Lee RJ, Shaw T, Sandquist M, Partridge LD. Mechanism of action of the non-steroidal anti-inflammatory drug flufenamate on [Ca2+]i and Ca(2+)-activated currents in neurons. Cell Calcium 1996; 19:431-8. [PMID: 8793183 DOI: 10.1016/s0143-4160(96)90116-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
We have shown previously that the non-steroidal anti-inflammatory drug flufenamate (FFA) causes a maintained increase in [Ca2+]i and transient increases in a Ca(2+)-activated nonselective cation current (ICAN) and a Ca(2+)-activated slow, outward Cl- current (lo-slow) in molluscan neurons [Shaw T., Lee R.J., Partridge L.D. Action of diphenylamine carboxylate derivatives, a family of non-steroidal anti-inflammatory drugs, on [Ca2+]i and Ca(2+)-activated channels in neurons. Neurosci Lett 1995; 190:121-124]. Here we demonstrate that pretreatment of neurons with 10 microM thapsigargin eliminates the FFA-induced increase in [Ca2+]i and substantially reduces both ICAN and Io-slow supporting the hypothesis that the FFA-induced increase in [Ca2+]i results primarily from Ca2+ release from a thapsigargin-sensitive intracellular store. The [Ca2+]i response appears to be sustained, not by influx of extracellular Ca2+, but by inhibitory effects of FFA on Ca2+ removal from the cytosol. Inhibition of Ca2+ efflux may be an important component of the FFA-induced activation of both ICAN and Io-slow, as Ca2+ release by thapsigargin alone is not sufficient to activate either current. Our data also demonstrate that the effects of FFA on [Ca2+]i, ICAN and Io-slow are reversible and suggest that protein phosphorylation as well as an increase in [Ca2+]i are involved in the FFA-induced activation of Io-slow. Effects on neuronal Ca2+ handling as well as activation of ICAN or Io-slow may partially explain the analgesic effects of FFA.
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Affiliation(s)
- R J Lee
- Department of Pathology, University of New Mexico School of Medicine, Albuquerque, USA
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Phipps DJ, Branch DR, Schlichter LC. Chloride-channel block inhibits T lymphocyte activation and signalling. Cell Signal 1996; 8:141-9. [PMID: 8730516 DOI: 10.1016/0898-6568(95)02039-x] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Both large- and small-conductance chloride (Cl-) channels have been found in human T lymphocytes; however, apart from possible roles in mediating regulatory volume decrease, their functions are not understood. We have used patch-clamp electrophysiology, Ca2+ spectrofluorometry, and Western blot assay for phosphotyrosine to investigate the effects of blocking Cl- channels on proliferation and on specific events in the activation of normal human T cells. Four chemically distinct Cl- channel blockers inhibited both the small-conductance Cl- channels and phytohemagglutinin (PHA)-induced lymphocyte proliferation in a similar dose-dependent manner; their order of potency was 5-nitro-2(3-phenylpropylamino)-benzoic acid (NPPB) > 4,4'-diisothiocyano-2,2'-disulfonic acid (DIDS) > flufenamic acid >> IAA-94. The Cl- channel blockers inhibited both the PHA-induced mobilization of Ca2+ and the rapid tyrosine phosphorylation of several polypeptides. Cell proliferation was not rescued by the Ca+ ionophore ionomycin or by addition of exogenous interleukin-2 (IL-2). Moreover, the blockers also inhibited phosphotyrosine expression in IL-2-treated, activated lymphoblasts. Thus, our results support a role for Cl- channels in early, PHA-evoked signalling and in later, II-2-dependent stages of lymphocyte activation and proliferation.
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Affiliation(s)
- D J Phipps
- Toronto Hospital Research Institute, Ontario, Canada
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