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Balducci V, Faris P, Balbi C, Costa A, Negri S, Rosti V, Bollini S, Moccia F. The human amniotic fluid stem cell secretome triggers intracellular Ca 2+ oscillations, NF-κB nuclear translocation and tube formation in human endothelial colony-forming cells. J Cell Mol Med 2021; 25:8074-8086. [PMID: 34288391 PMCID: PMC8358861 DOI: 10.1111/jcmm.16739] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Revised: 05/10/2021] [Accepted: 05/14/2021] [Indexed: 12/15/2022] Open
Abstract
Second trimester foetal human amniotic fluid‐derived stem cells (hAFS) have been shown to possess remarkable cardioprotective paracrine potential in different preclinical models of myocardial injury and drug‐induced cardiotoxicity. The hAFS secretome, namely the total soluble factors released by cells in their conditioned medium (hAFS‐CM), can also strongly sustain in vivo angiogenesis in a murine model of acute myocardial infarction (MI) and stimulates human endothelial colony‐forming cells (ECFCs), the only truly recognized endothelial progenitor, to form capillary‐like structures in vitro. Preliminary work demonstrated that the hypoxic hAFS secretome (hAFS‐CMHypo) triggers intracellular Ca2+ oscillations in human ECFCs, but the underlying mechanisms and the downstream Ca2+‐dependent effectors remain elusive. Herein, we found that the secretome obtained by hAFS undergoing hypoxic preconditioning induced intracellular Ca2+ oscillations by promoting extracellular Ca2+ entry through Transient Receptor Potential Vanilloid 4 (TRPV4). TRPV4‐mediated Ca2+ entry, in turn, promoted the concerted interplay between inositol‐1,4,5‐trisphosphate‐ and nicotinic acid adenine dinucleotide phosphate‐induced endogenous Ca2+ release and store‐operated Ca2+ entry (SOCE). hAFS‐CMHypo‐induced intracellular Ca2+ oscillations resulted in the nuclear translocation of the Ca2+‐sensitive transcription factor p65 NF‐κB. Finally, inhibition of either intracellular Ca2+ oscillations or NF‐κB activity prevented hAFS‐CMHypo‐induced ECFC tube formation. These data shed novel light on the molecular mechanisms whereby hAFS‐CMHypo induces angiogenesis, thus providing useful insights for future therapeutic strategies against ischaemic‐related myocardial injury.
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Affiliation(s)
- Valentina Balducci
- Department of Biology and Biotechnology "Lazzaro Spallanzani", Laboratory of General Physiology, University of Pavia, Pavia, Italy
| | - Pawan Faris
- Department of Biology and Biotechnology "Lazzaro Spallanzani", Laboratory of General Physiology, University of Pavia, Pavia, Italy
| | - Carolina Balbi
- Department of Experimental Medicine (DIMES), University of Genova, Genova, Italy
| | - Ambra Costa
- Department of Experimental Medicine (DIMES), University of Genova, Genova, Italy
| | - Sharon Negri
- Department of Biology and Biotechnology "Lazzaro Spallanzani", Laboratory of General Physiology, University of Pavia, Pavia, Italy
| | - Vittorio Rosti
- Laboratory of Biochemistry, Biotechnology and Advanced Diagnostic, Myelofibrosis Study Centre, Fondazione IRCCS Policlinico San Matteo, Pavia, Italy
| | - Sveva Bollini
- Department of Experimental Medicine (DIMES), University of Genova, Genova, Italy
| | - Francesco Moccia
- Department of Biology and Biotechnology "Lazzaro Spallanzani", Laboratory of General Physiology, University of Pavia, Pavia, Italy
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Breitholtz M, Ivanov P, Ek K, Gorokhova E. Calmodulin inhibition as a mode of action of antifungal imidazole pharmaceuticals in non-target organisms. Toxicol Res (Camb) 2020; 9:425-430. [PMID: 32905197 PMCID: PMC7467228 DOI: 10.1093/toxres/tfaa039] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Revised: 05/06/2020] [Accepted: 05/15/2020] [Indexed: 01/08/2023] Open
Abstract
To improve assessment of risks associated with pharmaceutical contamination of the environment, it is crucial to understand effects and mode of action of drugs in non-target species. The evidence is accumulating that species with well-conserved drug targets are prone to be at risk when exposed to pharmaceuticals. An interesting group of pharmaceuticals released into the environment is imidazoles, antifungal agents with inhibition of ergosterol synthesis as a primary mode of action in fungi. However, imidazoles have also been identified as competitive antagonists of calmodulin (CaM), a calcium-binding protein with phylogenetically conserved structure and function. Therefore, imidazoles would act as CaM inhibitors in various organisms, including those with limited capacity to synthesize sterols, such as arthropods. We hypothesized that effects observed in crustaceans exposed to imidazoles are related to the CaM inhibition and CaM-dependent nitric oxide (NO) synthesis. To test this hypothesis, we measured (i) CaM levels and its gene expression, (ii) NO accumulation and (iii) gene expression of NO synthase (NOS1 and NOS2), in the cladoceran Daphnia magna exposed to miconazole, a model imidazole drug. Whereas significantly increased CaM gene expression and its cellular allocation were observed, supporting the hypothesized mode of action, no changes occurred in either NO synthase expression or NO levels in the exposed animals. These findings suggest that CaM inhibition by miconazole leads to protein overexpression that compensates for the loss in the protein activity, with no measurable downstream effects on NO pathways. The inhibition of CaM in D. magna may have implications for effect assessment of exposure to mixtures of imidazoles in aquatic non-target species.
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Affiliation(s)
- Magnus Breitholtz
- Department of Environmental Science and Analytical Chemistry , Stockholm University, SE-106 91, Sweden
| | - Pavel Ivanov
- Department of Environmental Science and Analytical Chemistry , Stockholm University, SE-106 91, Sweden
| | - Karin Ek
- Department of Environmental Science and Analytical Chemistry , Stockholm University, SE-106 91, Sweden
| | - Elena Gorokhova
- Department of Environmental Science and Analytical Chemistry , Stockholm University, SE-106 91, Sweden
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3
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Arachidonic Acid Evokes an Increase in Intracellular Ca 2+ Concentration and Nitric Oxide Production in Endothelial Cells from Human Brain Microcirculation. Cells 2019; 8:cells8070689. [PMID: 31323976 PMCID: PMC6678502 DOI: 10.3390/cells8070689] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Revised: 07/04/2019] [Accepted: 07/08/2019] [Indexed: 12/12/2022] Open
Abstract
It has long been known that the conditionally essential polyunsaturated arachidonic acid (AA) regulates cerebral blood flow (CBF) through its metabolites prostaglandin E2 and epoxyeicosatrienoic acid, which act on vascular smooth muscle cells and pericytes to vasorelax cerebral microvessels. However, AA may also elicit endothelial nitric oxide (NO) release through an increase in intracellular Ca2+ concentration ([Ca2+]i). Herein, we adopted Ca2+ and NO imaging, combined with immunoblotting, to assess whether AA induces intracellular Ca2+ signals and NO release in the human brain microvascular endothelial cell line hCMEC/D3. AA caused a dose-dependent increase in [Ca2+]i that was mimicked by the not-metabolizable analogue, eicosatetraynoic acid. The Ca2+ response to AA was patterned by endoplasmic reticulum Ca2+ release through type 3 inositol-1,4,5-trisphosphate receptors, lysosomal Ca2+ mobilization through two-pore channels 1 and 2 (TPC1-2), and extracellular Ca2+ influx through transient receptor potential vanilloid 4 (TRPV4). In addition, AA-evoked Ca2+ signals resulted in robust NO release, but this signal was considerably delayed as compared to the accompanying Ca2+ wave and was essentially mediated by TPC1-2 and TRPV4. Overall, these data provide the first evidence that AA elicits Ca2+-dependent NO release from a human cerebrovascular endothelial cell line, but they seemingly rule out the possibility that this NO signal could acutely modulate neurovascular coupling.
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Turovsky EA, Zinchenko VP, Kaimachnikov NP. Attenuation of calmodulin regulation evokes Ca 2+ oscillations: evidence for the involvement of intracellular arachidonate-activated channels and connexons. Mol Cell Biochem 2019; 456:191-204. [PMID: 30756222 DOI: 10.1007/s11010-019-03504-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Accepted: 02/01/2019] [Indexed: 01/02/2023]
Abstract
Intracellular Са2+ controls its own level by regulation of Ca2+ transport across the plasma and organellar membranes, often acting via calmodulin (CaM). Drugs antagonizing CaM action induce an increase in cytosolic Ca2+ concentration in different cells. We have found persistent Са2+ oscillations in cultured white adipocytes in response to calmidazolium (CMZ). They appeared at [CMZ] > 1 μM as repetitive sharp spikes mainly superimposed on a transient or elevated baseline. Similar oscillations were observed when we used trifluoperazine. Oscillations evoked by 5 μM CMZ resulted from the release of stored Ca2+ and were supported by Са2+ entry. Inhibition of store-operated channels by YM-58483 or 2-APB did not change the responses. Phospholipase A2 inhibited by AACOCF3 was responsible for initial Ca2+ mobilization, but not for subsequent oscillations, whereas inhibition of iPLA2 by BEL had no effect. Phospholipase C was partially involved in both stages as revealed with U73122. Intracellular Са2+ stores engaged by CMZ were entirely dependent on thapsigargin. The oscillations existed in the presence of inhibitors of ryanodine or inositol 1,4,5-trisphosphate receptors, or antagonists of Ca2+ transport by lysosome-like acidic stores. Carbenoxolone or octanol, blockers of hemichannels (connexons), when applied for two hours, prevented oscillations but did not affect the initial Са2+ release. Incubation with La3+ for 2 or 24 h inhibited all responses to CMZ, retaining the thapsigargin-induced Ca2+ rise. These results suggest that Ca2+-CaM regulation suppresses La3+-sensitive channels in non-acidic organelles, of which arachidonate-activated channels initiate Ca2+ oscillations, and connexons are intimately implicated in their generation mechanism.
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Affiliation(s)
- Egor A Turovsky
- Institute of Cell Biophysics of the Russian Academy of Sciences, Pushchino, Moscow Region, Russia, 142290
| | - Valery P Zinchenko
- Institute of Cell Biophysics of the Russian Academy of Sciences, Pushchino, Moscow Region, Russia, 142290
| | - Nikolai P Kaimachnikov
- Institute of Cell Biophysics of the Russian Academy of Sciences, Pushchino, Moscow Region, Russia, 142290.
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Zuccolo E, Laforenza U, Negri S, Botta L, Berra-Romani R, Faris P, Scarpellino G, Forcaia G, Pellavio G, Sancini G, Moccia F. Muscarinic M5 receptors trigger acetylcholine-induced Ca 2+ signals and nitric oxide release in human brain microvascular endothelial cells. J Cell Physiol 2018; 234:4540-4562. [PMID: 30191989 DOI: 10.1002/jcp.27234] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Accepted: 07/24/2018] [Indexed: 12/13/2022]
Abstract
Basal forebrain neurons control cerebral blood flow (CBF) by releasing acetylcholine (Ach), which binds to endothelial muscarinic receptors to induce nitric (NO) release and vasodilation in intraparenchymal arterioles. Nevertheless, the mechanism whereby Ach stimulates human brain microvascular endothelial cells to produce NO is still unknown. Herein, we sought to assess whether Ach stimulates NO production in a Ca2+ -dependent manner in hCMEC/D3 cells, a widespread model of human brain microvascular endothelial cells. Ach induced a dose-dependent increase in intracellular Ca2+ concentration ([Ca2+ ]i ) that was prevented by the genetic blockade of M5 muscarinic receptors (M5-mAchRs), which was the only mAchR isoform coupled to phospholipase Cβ (PLCβ) present in hCMEC/D3 cells. A comprehensive real-time polymerase chain reaction analysis revealed the expression of the transcripts encoding for type 3 inositol-1,4,5-trisphosphate receptors (InsP3 R3), two-pore channels 1 and 2 (TPC1-2), Stim2, Orai1-3. Pharmacological manipulation showed that the Ca2+ response to Ach was mediated by InsP3 R3, TPC1-2, and store-operated Ca2+ entry (SOCE). Ach-induced NO release, in turn, was inhibited in cells deficient of M5-mAchRs. Likewise, Ach failed to increase NO levels in the presence of l-NAME, a selective NOS inhibitor, or BAPTA, a membrane-permeant intracellular Ca2+ buffer. Moreover, the pharmacological blockade of the Ca2+ response to Ach also inhibited the accompanying NO production. These data demonstrate for the first time that synaptically released Ach may trigger NO release in human brain microvascular endothelial cells by stimulating a Ca2+ signal via M5-mAchRs.
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Affiliation(s)
- Estella Zuccolo
- Department of Biology and Biotechnology, "Lazzaro Spallanzani," Laboratory of General Physiology, University of Pavia, Pavia, Italy
| | - Umberto Laforenza
- Department of Molecular Medicine, Human Physiology Unit, University of Pavia, Pavia, Italy
| | - Sharon Negri
- Department of Biology and Biotechnology, "Lazzaro Spallanzani," Laboratory of General Physiology, University of Pavia, Pavia, Italy
| | - Laura Botta
- Department of Biology and Biotechnology, "Lazzaro Spallanzani," Laboratory of General Physiology, University of Pavia, Pavia, Italy
| | - Roberto Berra-Romani
- Department of Biomedicine, School of Medicine, Benemérita Universidad Autónoma de Puebla, Puebla, Mexico
| | - Pawan Faris
- Department of Biology and Biotechnology, "Lazzaro Spallanzani," Laboratory of General Physiology, University of Pavia, Pavia, Italy.,Department of Biology, College of Science, Salahaddin University, Erbil, Iraq
| | - Giorgia Scarpellino
- Department of Biology and Biotechnology, "Lazzaro Spallanzani," Laboratory of General Physiology, University of Pavia, Pavia, Italy
| | - Greta Forcaia
- Department of Experimental Medicine, University of Milano-Bicocca, Monza, Italy
| | - Giorgia Pellavio
- Department of Molecular Medicine, Human Physiology Unit, University of Pavia, Pavia, Italy
| | - Giulio Sancini
- Department of Experimental Medicine, University of Milano-Bicocca, Monza, Italy
| | - Francesco Moccia
- Department of Biology and Biotechnology, "Lazzaro Spallanzani," Laboratory of General Physiology, University of Pavia, Pavia, Italy
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Pierro C, Zhang X, Kankeu C, Trebak M, Bootman MD, Roderick HL. Oncogenic KRAS suppresses store-operated Ca 2+ entry and I CRAC through ERK pathway-dependent remodelling of STIM expression in colorectal cancer cell lines. Cell Calcium 2018; 72:70-80. [PMID: 29748135 PMCID: PMC6291847 DOI: 10.1016/j.ceca.2018.03.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Revised: 03/13/2018] [Accepted: 03/13/2018] [Indexed: 12/30/2022]
Abstract
The KRAS GTPase plays a fundamental role in transducing signals from plasma membrane growth factor receptors to downstream signalling pathways controlling cell proliferation, survival and migration. Activating KRAS mutations are found in 20% of all cancers and in up to 40% of colorectal cancers, where they contribute to dysregulation of cell processes underlying oncogenic transformation. Multiple KRAS-regulated cell functions are also influenced by changes in intracellular Ca2+ levels that are concurrently modified by receptor signalling pathways. Suppression of intracellular Ca2+ release mechanisms can confer a survival advantage in cancer cells, and changes in Ca2+ entry across the plasma membrane modulate cell migration and proliferation. However, inconsistent remodelling of Ca2+ influx and its signalling role has been reported in studies of transformed cells. To isolate the interaction between altered Ca2+ handling and mutated KRAS in colorectal cancer, we have previously employed isogenic cell line pairs, differing by the presence of an oncogenic KRAS allele (encoding KRASG13D), and have shown that reduced Ca2+ release from the ER and mitochondrial Ca2+ uptake contributes to the survival advantage conferred by oncogenic KRAS. Here we show in the same cell lines, that Store-Operated Ca2+ Entry (SOCE) and its underlying current, ICRAC are under the influence of KRASG13D. Specifically, deletion of the oncogenic KRAS allele resulted in enhanced STIM1 expression and greater Ca2+ influx. Consistent with the role of KRAS in the activation of the ERK pathway, MEK inhibition in cells with KRASG13D resulted in increased STIM1 expression. Further, ectopic expression of STIM1 in HCT 116 cells (which express KRASG13D) rescued SOCE, demonstrating a fundamental role of STIM1 in suppression of Ca2+ entry downstream of KRASG13D. These results add to the understanding of how ERK controls cancer cell physiology and highlight STIM1 as an important biomarker in cancerogenesis.
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Affiliation(s)
- Cristina Pierro
- Laboratory of Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium; Previously at Babraham Institute, Babraham Research Campus, Cambridge, UK
| | - Xuexin Zhang
- Department of Cellular and Molecular Physiology and Penn State Hershey Cancer Institute, Penn State College of Medicine, Hershey PA 17033, United States
| | - Cynthia Kankeu
- Laboratory of Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium
| | - Mohamed Trebak
- Department of Cellular and Molecular Physiology and Penn State Hershey Cancer Institute, Penn State College of Medicine, Hershey PA 17033, United States
| | - Martin D Bootman
- Previously at Babraham Institute, Babraham Research Campus, Cambridge, UK; School of Life, Health and Chemical Sciences, The Open University, UK
| | - H Llewelyn Roderick
- Laboratory of Experimental Cardiology, Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium; Previously at Babraham Institute, Babraham Research Campus, Cambridge, UK.
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Zuccolo E, Di Buduo C, Lodola F, Orecchioni S, Scarpellino G, Kheder DA, Poletto V, Guerra G, Bertolini F, Balduini A, Rosti V, Moccia F. Stromal Cell-Derived Factor-1α Promotes Endothelial Colony-Forming Cell Migration Through the Ca2+-Dependent Activation of the Extracellular Signal-Regulated Kinase 1/2 and Phosphoinositide 3-Kinase/AKT Pathways. Stem Cells Dev 2018; 27:23-34. [DOI: 10.1089/scd.2017.0114] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Affiliation(s)
- Estella Zuccolo
- Laboratory of General Physiology, Department of Biology and Biotechnology “Lazzaro Spallanzani,” University of Pavia, Pavia, Italy
| | - Christian Di Buduo
- Department of Molecular Medicine, University of Pavia, Pavia, Italy
- Laboratory of Biochemistry, Biotechnology, and Advanced Diagnosis, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) San Matteo Foundation, Pavia, Italy
| | - Francesco Lodola
- Laboratory of General Physiology, Department of Biology and Biotechnology “Lazzaro Spallanzani,” University of Pavia, Pavia, Italy
| | - Stefania Orecchioni
- Laboratory of Hematology–Oncology, European Institute of Oncology, Milan, Italy
| | - Giorgia Scarpellino
- Laboratory of General Physiology, Department of Biology and Biotechnology “Lazzaro Spallanzani,” University of Pavia, Pavia, Italy
| | - Dlzar Ali Kheder
- Laboratory of General Physiology, Department of Biology and Biotechnology “Lazzaro Spallanzani,” University of Pavia, Pavia, Italy
- Department of Biology, Faculty of Science, University of Zakho, Zakho, Kurdistan-Region of Iraq
| | - Valentina Poletto
- Laboratory of Biochemistry, Biotechnology, and Advanced Diagnosis, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) San Matteo Foundation, Pavia, Italy
| | - Germano Guerra
- Department of Medicine and Health Sciences “Vincenzo Tiberio,” University of Molise, Campobasso, Italy
| | - Francesco Bertolini
- Laboratory of Hematology–Oncology, European Institute of Oncology, Milan, Italy
| | - Alessandra Balduini
- Department of Molecular Medicine, University of Pavia, Pavia, Italy
- Laboratory of Biochemistry, Biotechnology, and Advanced Diagnosis, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) San Matteo Foundation, Pavia, Italy
- Department of Biomedical Engineering, Tufts University, Medford, Massachusetts
| | - Vittorio Rosti
- Laboratory of Biochemistry, Biotechnology, and Advanced Diagnosis, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) San Matteo Foundation, Pavia, Italy
| | - Francesco Moccia
- Laboratory of General Physiology, Department of Biology and Biotechnology “Lazzaro Spallanzani,” University of Pavia, Pavia, Italy
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8
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P2X7 receptor large pore signaling in avian Müller glial cells. J Bioenerg Biomembr 2017; 49:215-229. [PMID: 28573491 DOI: 10.1007/s10863-017-9717-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Accepted: 05/11/2017] [Indexed: 01/15/2023]
Abstract
ATP is a pleiotropic molecule that promotes extra- and intracellular signaling to regulate numerous functions. This nucleotide activates purine and pyrimidine receptors at the plasma membrane, categorized as ionotropic P2X or G-protein-coupled receptor (GPCR) P2Y receptors. P2X are ligand-gated ion channel receptors, expressed in both retinal neurons and Müller cells leading to neuron-glia communication, calcium waves and neurovascular coupling. However, how P2X pore is formed upon ATP activation and how signaling pathways regulates the complex is still a matter of controversy. Here we studied the properties of the P2X7 receptor (P2X7R) using electrophysiology, single cell Ca2+ imaging, and dye uptake assay in purified avian Müller glia in culture. Our data show that ATP (or benzoyl-benzoyl ATP, BzATP) evoked large inward currents in patch-clamp studies while addition of P2X7R antagonist such as brilliant Blue G (BBG), abolished these currents. Ruthenium red (RU-2), a general transient receptor potential (TRP) inhibitor, reduced currents induced by ATP. Our data also point to the involvement of mitogen activated protein kinase (MAPK), phosphoinositide 3-kinase (PI3K), Ca2+-calmodulin kinase II (CAMKII), microtubules or protein kinase C (PKC) modulating ATP-induced ionic current in Müller cells. We show that ATP induced Ca2+ influx, partially inhibited by P2X7R antagonists (oxidized ATP or BBG), and totally inhibited by blockers of other pores such as transient receptor potential (TRPs) or connexin hemichannel. Additionally, MAPK, PKC, PI3K or CAMKII inhibitors also are involved in the modulation of intracellular calcium signaling. Finally, ATP induced 80-90% of dye uptake in Muller glia cells, while oxidized ATP (oATP), BBG or A740003 inhibited this effect. We conclude that large conductance channel and other P2XRs are not involved in the ATP-induced dye uptake, but signaling pathways such as MAPK, PI3-K, microtubules or PKC are involved in pore formation.
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Jethwa SA, Leah EJ, Zhang Q, Bright NA, Oxley D, Bootman MD, Rudge SA, Wakelam MJO. Exosomes bind to autotaxin and act as a physiological delivery mechanism to stimulate LPA receptor signalling in cells. J Cell Sci 2016; 129:3948-3957. [PMID: 27557622 DOI: 10.1242/jcs.184424] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Accepted: 08/14/2016] [Indexed: 12/23/2022] Open
Abstract
Autotaxin (ATX; also known as ENPP2), the lysophospholipase responsible for generating the lipid receptor agonist lysophosphatidic acid (LPA), is a secreted enzyme. Here we show that, once secreted, ATX can bind to the surface of cell-secreted exosomes. Exosome-bound ATX is catalytically active and carries generated LPA. Once bound to a cell, through specific integrin interactions, ATX releases the LPA to activate cell surface G-protein-coupled receptors of LPA; inhibition of signalling by the receptor antagonist Ki1642 suggests that these receptors are LPAR1 and LPAR3. The binding stimulates downstream signalling, including phosphorylation of AKT and mitogen-activated protein kinases, the release of intracellular stored Ca2+ and cell migration. We propose that exosomal binding of LPA-loaded ATX provides a means of efficiently delivering the lipid agonist to cell surface receptors to promote signalling. We further propose that this is a means by which ATX-LPA signalling operates physiologically.
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Affiliation(s)
- Susanna A Jethwa
- Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK
| | - Emma J Leah
- Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK
| | - Qifeng Zhang
- Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK
| | - Nicholas A Bright
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, UK
| | - David Oxley
- Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK
| | - Martin D Bootman
- Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK
| | - Simon A Rudge
- Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK
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Budu A, Gomes MM, Melo PM, El Chamy Maluf S, Bagnaresi P, Azevedo MF, Carmona AK, Gazarini ML. Calmidazolium evokes high calcium fluctuations in Plasmodium falciparum. Cell Signal 2015; 28:125-135. [PMID: 26689736 DOI: 10.1016/j.cellsig.2015.12.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Revised: 11/30/2015] [Accepted: 12/07/2015] [Indexed: 10/22/2022]
Abstract
Calcium and calmodulin (CaM) are important players in eukaryote cell signaling. In the present study, by using a knockin approach, we demonstrated the expression and localization of CaM in all erythrocytic stages of Plasmodium falciparum. Under extracellular Ca(2+)-free conditions, calmidazolium (CZ), a potent CaM inhibitor, promoted a transient cytosolic calcium ([Ca(2+)]cyt) increase in isolated trophozoites, indicating that CZ mobilizes intracellular sources of calcium. In the same extracellular Ca(2+)-free conditions, the [Ca(2+)]cyt rise elicited by CZ treatment was ~3.5 fold higher when the endoplasmic reticulum (ER) calcium store was previously depleted ruling out the mobilization of calcium from the ER by CZ. The effects of the Ca(2+)/H(+) ionophore ionomycin (ION) and the Na(+)/H(+) ionophore monensin (MON) suggest that the [Ca(2+)]cyt-increasing effect of CZ is driven by the removal of Ca(2+) from at least one Ca(2+)-CaM-related (CaMR) protein as well as by the mobilization of Ca(2+) from intracellular acidic calcium stores. Moreover, we showed that the mitochondrion participates in the sequestration of the cytosolic Ca(2+) elicited by CZ. Finally, the modulation of membrane Ca(2+) channels by CZ and thapsigargin (THG) was demonstrated. The opened channels were blocked by the unspecific calcium channel blocker Co(2+) but not by 2-APB (capacitative calcium entry inhibitor) or nifedipine (L-type Ca(2+) channel inhibitor). Taken together, the results suggested that one CaMR protein is an important modulator of calcium signaling and homeostasis during the Plasmodium intraerythrocytic cell cycle, working as a relevant intracellular Ca(2+) reservoir in the parasite.
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Affiliation(s)
- Alexandre Budu
- Departamento de Biofísica, Universidade Federal de São Paulo, São Paulo, SP, Brazil
| | - Mayrim M Gomes
- Departamento de Biociências, Universidade Federal de São Paulo, Santos, SP, Brazil
| | - Pollyana M Melo
- Departamento de Biofísica, Universidade Federal de São Paulo, São Paulo, SP, Brazil
| | - Sarah El Chamy Maluf
- Departamento de Biofísica, Universidade Federal de São Paulo, São Paulo, SP, Brazil
| | - Piero Bagnaresi
- Departamento de Biofísica, Universidade Federal de São Paulo, São Paulo, SP, Brazil
| | - Mauro F Azevedo
- Instituto de Ciências Biomédicas, Universidade de São Paulo, SP, Brazil
| | - Adriana K Carmona
- Departamento de Biofísica, Universidade Federal de São Paulo, São Paulo, SP, Brazil.
| | - Marcos L Gazarini
- Departamento de Biociências, Universidade Federal de São Paulo, Santos, SP, Brazil.
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11
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Jensen LE, Bultynck G, Luyten T, Amijee H, Bootman MD, Roderick HL. Alzheimer's disease-associated peptide Aβ42 mobilizes ER Ca(2+) via InsP3R-dependent and -independent mechanisms. Front Mol Neurosci 2013; 6:36. [PMID: 24204331 PMCID: PMC3817845 DOI: 10.3389/fnmol.2013.00036] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2013] [Accepted: 10/14/2013] [Indexed: 11/13/2022] Open
Abstract
Dysregulation of Ca2+ homeostasis is considered to contribute to the toxic action of the Alzheimer's disease (AD)-associated amyloid-β-peptide (Aβ). Ca2+ fluxes across the plasma membrane and release from intracellular stores have both been reported to underlie the Ca2+ fluxes induced by Aβ42. Here, we investigated the contribution of Ca2+ release from the endoplasmic reticulum (ER) to the effects of Aβ42 upon Ca2+ homeostasis and the mechanism by which Aβ42 elicited these effects. Consistent with previous reports, application of soluble oligomeric forms of Aβ42 induced an elevation in intracellular Ca2+. The Aβ42-stimulated Ca2+ signals persisted in the absence of extracellular Ca2+ indicating a significant contribution of Ca2+ release from the ER Ca2+ store to the generation of these signals. Moreover, inositol 1,4,5-trisphosphate (InsP3) signaling contributed to Aβ42-stimulated Ca2+ release. The Ca2+ mobilizing effect of Aβ42 was also observed when applied to permeabilized cells deficient in InsP3 receptors, revealing an additional direct effect of Aβ42 upon the ER, and a mechanism for induction of toxicity by intracellular Aβ42.
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Affiliation(s)
- Laura E Jensen
- Babraham Institute, Babraham Research Campus Babraham, Cambridge, UK
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12
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Marandykina A, Palacios-Prado N, Rimkutė L, Skeberdis VA, Bukauskas FF. Regulation of connexin36 gap junction channels by n-alkanols and arachidonic acid. J Physiol 2013; 591:2087-101. [PMID: 23420660 PMCID: PMC3634521 DOI: 10.1113/jphysiol.2013.250910] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2013] [Accepted: 02/13/2013] [Indexed: 12/18/2022] Open
Abstract
We examined junctional conductance (gj) and its dependence on transjunctional voltage in gap junction (GJ) channels formed of wild-type connexin36 (Cx36) or its fusion form with green fluorescent protein (Cx36-EGFP) transfected in HeLa cells or endogenously expressed in primary culture of pancreatic β-cells. Only a very small fraction (∼0.8%) of Cx36-EGFP channels assembled into junctional plaques of GJs were open under control conditions. We found that short carbon chain n-alkanols (SCCAs) increased gj, while long carbon chain n-alkanols resulted in full uncoupling; cutoff is between heptanol and octanol. The fraction of functional channels and gj increased several fold under an exposure to SCCAs, or during reduction of endogenous levels of arachidonic acid (AA) by exposure to fatty acid-free BSA or cytosolic phospholipase A2 inhibitors. Moreover, uncoupling caused by exogenously applied AA can be rescued by BSA, which binds AA and other polyunsaturated fatty acids (PUFAs), but not by BSA modified with 1,2-cyclohexanedione, which does not bind AA and other PUFAs. We propose that under control conditions, Cx36 GJ channels in HeLa transfectants and β-cells are inhibited by endogenous AA, which stabilizes a closed conformational state of the channel that leads to extremely low fraction of functional channels. In addition, SCCAs increase gj by interfering with endogenous AA-dependent inhibition, increasing open probability and the fraction of functional channels.
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Affiliation(s)
- Alina Marandykina
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461, USA
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13
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Varadarajan S, Tanaka K, Smalley JL, Bampton ETW, Pellecchia M, Dinsdale D, Willars GB, Cohen GM. Endoplasmic reticulum membrane reorganization is regulated by ionic homeostasis. PLoS One 2013; 8:e56603. [PMID: 23457590 PMCID: PMC3574070 DOI: 10.1371/journal.pone.0056603] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2012] [Accepted: 01/14/2013] [Indexed: 01/01/2023] Open
Abstract
Recently we described a new, evolutionarily conserved cellular stress response characterized by a reversible reorganization of endoplasmic reticulum (ER) membranes that is distinct from canonical ER stress and the unfolded protein response (UPR). Apogossypol, a putative broad spectrum BCL-2 family antagonist, was the prototype compound used to induce this ER membrane reorganization. Following microarray analysis of cells treated with apogossypol, we used connectivity mapping to identify a wide range of structurally diverse chemicals from different pharmacological classes and established their ability to induce ER membrane reorganization. Such structural diversity suggests that the mechanisms initiating ER membrane reorganization are also diverse and a major objective of the present study was to identify potentially common features of these mechanisms. In order to explore this, we used hierarchical clustering of transcription profiles for a number of chemicals that induce membrane reorganization and discovered two distinct clusters. One cluster contained chemicals with known effects on Ca2+ homeostasis. Support for this was provided by the findings that ER membrane reorganization was induced by agents that either deplete ER Ca2+ (thapsigargin) or cause an alteration in cellular Ca2+ handling (calmodulin antagonists). Furthermore, overexpression of the ER luminal Ca2+ sensor, STIM1, also evoked ER membrane reorganization. Although perturbation of Ca2+ homeostasis was clearly one mechanism by which some agents induced ER membrane reorganization, influx of extracellular Na+ but not Ca2+ was required for ER membrane reorganization induced by apogossypol and the related BCL-2 family antagonist, TW37, in both human and yeast cells. Not only is this novel, non-canonical ER stress response evolutionary conserved but so also are aspects of the mechanism of formation of ER membrane aggregates. Thus perturbation of ionic homeostasis is important in the regulation of ER membrane reorganization.
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Affiliation(s)
| | - Kayoko Tanaka
- Department of Biochemistry, University of Leicester, Leicester, United Kingdom
| | - Joshua L. Smalley
- MRC Toxicology Unit, University of Leicester, Leicester, United Kingdom
| | | | | | - David Dinsdale
- MRC Toxicology Unit, University of Leicester, Leicester, United Kingdom
| | - Gary B. Willars
- Department of Cell Physiology and Pharmacology, University of Leicester, Leicester, United Kingdom
| | - Gerald M. Cohen
- MRC Toxicology Unit, University of Leicester, Leicester, United Kingdom
- Department of Biochemistry, University of Leicester, Leicester, United Kingdom
- * E-mail:
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Chen L, Meng Q, Yu X, Li C, Zhang C, Cui C, Luo D. Possible mechanisms underlying the biphasic regulatory effects of arachidonic acid on Ca2+ signaling in HEK293 cells. Cell Signal 2012; 24:1565-72. [PMID: 22484156 DOI: 10.1016/j.cellsig.2012.03.016] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2012] [Revised: 03/21/2012] [Accepted: 03/21/2012] [Indexed: 12/01/2022]
Abstract
Arachidonic acid (AA), an endogenous lipid signal molecule released from membrane upon cell activation, modulates intracellular Ca(2+) ([Ca(2+)](i)) signaling positively and negatively. However, the mechanisms underlying the biphasic effects of AA are rather obscure. Using probes for measurements of [Ca(2+)](i) and fluidity of plasma membrane (PM)/endoplasmic reticulum (ER), immunostaining, immunoblotting and shRNA interference approaches, we found that AA at low concentration, 3 μM, reduced the PM fluidity by activating PKCα and PKCβII translocation to PM and also the ER fluidity directly. In accordance, 3 μM AA did not impact the basal [Ca(2+)](i) but significantly suppressed the thapsigargin-induced Ca(2+) release and Ca(2+) influx. Inhibition of PKC with Gö6983 or knockdown of PKCα or PKCβ using shRNA significantly attenuated the inhibitory effects of 3 μM AA on PM fluidity and agonist-induced Ca(2+) signal. However, AA at high concentration, 30 μM, caused robust release and entry of Ca(2+) accompanied by a facilitated PM fluidity but decreased ER fluidity and dramatic PKCβI and PKCβII redistribution in the ER. Compared with ursodeoxycholate acid, a membrane stabilizing agent that only inhibited the 30 μM AA-induced Ca(2+) influx by 45%, Gd(3+) at concentration of 10 μM could completely abolish both release and entry of Ca(2+) induced by AA, suggesting that the potentiated PM fluidity is not the only reason for AA eliciting Ca(2+) signal. Therefore, the study herein demonstrates that a lowered PM fluidity by PKC activation and a direct ER stabilization contribute significantly for AA downregulation of [Ca(2+)](i) response, while Gd(3+)-sensitive 'pores' in PM/ER play an important role in AA-induced Ca(2+) signal in HEK293 cells.
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Affiliation(s)
- Lihong Chen
- Department of Pharmacology, School of Chemical Biology & Pharmaceutical Sciences, Capital Medical University, Beijing, PR China
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15
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Jantaratnotai N, Choi HB, McLarnon JG. ATP stimulates chemokine production via a store-operated calcium entry pathway in C6 glioma cells. BMC Cancer 2009; 9:442. [PMID: 20003523 PMCID: PMC2807438 DOI: 10.1186/1471-2407-9-442] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2009] [Accepted: 12/15/2009] [Indexed: 11/25/2022] Open
Abstract
Background Glioma present as one of the most challenging cancers to treat, however, understanding of tumor cell biology is not well understood. Extracellular adenosine triphosphate (ATP) could serve as a critical signaling molecule regulating tumor development. This study has examined pharmacological modulation of calcium (Ca2+) entry through store-operated channels (SOC) on cellular expression and production of immune-cell mobilizing chemokines in ATP-stimulated C6 glioma cells. Methods Calcium spectrofluorometry was carried out to measure mobilization of intracellular Ca2+ [Ca2+]i following ATP stimulation of rat C6 glioma cells. Pretreatment with two inhibitors of SOC, SKF96365 or gadolinium, was used to examine for effects on [Ca2+]i. RT-PCR was performed to determine effects of purinergic stimulation on C6 cell expression of metabotropic P2Y receptors (P2YR) and the chemokines, monocyte chemoattractant protein-1 (MCP-1) and interleukin-8 (IL-8). ELISA was carried out to measure production of MCP-1 and IL-8 with ATP stimulation of glioma cells. Results Application of ATP (at 100 μM) to C6 glioma induced an increase in [Ca2+]i with the response exhibiting two components of decay. In the presence of the SOC inhibitors, SKF96365 or gadolinium, or with Ca2+-free solution, ATP responses lacked a slow phase suggesting the secondary component was due to SOC-mediated influx of Ca2+. RT-PCR confirmed expression of purinergic P2Y-subtype receptors in C6 cells which would serve as a precursor to activation of SOC. In addition, ATP-stimulated C6 cells showed enhanced expression of the chemokines, MCP-1 and IL-8, with SKF96365 or gadolinium effective in reducing chemokine expression. Gadolinium treatment of ATP-stimulated C6 cells was also found to inhibit the production of MCP-1 and IL-8. Conclusion These results suggest ATP-induced Ca2+ entry, mediated by activation of SOC in C6 glioma, as a mechanism leading to increased cellular expression and release of chemokines. Elevated levels of MCP-1 and IL-8 are predicted to enhance the mobility of tumor cells and promote recruitment of microglia into developing tumors thereby supporting tumor growth.
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Affiliation(s)
- Nattinee Jantaratnotai
- Department of Anesthesiology, Pharmacology and Therapeutics, Faculty of Medicine, University of British Columbia, 2176 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada.
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James LR, Griffiths CH, Garthwaite J, Bellamy TC. Inhibition of nitric oxide-activated guanylyl cyclase by calmodulin antagonists. Br J Pharmacol 2009; 158:1454-64. [PMID: 19845679 DOI: 10.1111/j.1476-5381.2009.00416.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
BACKGROUND AND PURPOSE Nitric oxide (NO) controls numerous physiological processes by activation of its receptor, guanylyl cyclase (sGC), leading to the accumulation of 3'-5' cyclic guanosine monophosphate (cGMP). Ca(2+)-calmodulin (CaM) regulates both NO synthesis by NO synthase and cGMP hydrolysis by phosphodiesterase-1. We report that, unexpectedly, the CaM antagonists, calmidazolium, phenoxybenzamine and trifluoperazine, also inhibited cGMP accumulation in cerebellar cells evoked by an exogenous NO donor, with IC(50) values of 11, 80 and 180 microM respectively. Here we sought to elucidate the underlying mechanism(s). EXPERIMENTAL APPROACH We used cerebellar cell suspensions to determine the influence of CaM antagonists on all steps of the NO-cGMP pathway. Homogenized tissue and purified enzyme were used to test effects of calmidazolium on sGC activity. KEY RESULTS Inhibition of cGMP accumulation in the cells did not depend on changes in intracellular Ca(2+) concentration. Degradation of cGMP and inactivation of NO were both inhibited by the CaM antagonists, ruling out increased loss of cGMP or NO as explanations. Instead, calmidazolium directly inhibited purified sGC (IC(50)= 10 microM). The inhibition was not in competition with NO, nor did it arise from displacement of the haem moiety from sGC. Calmidazolium decreased enzyme V(max) and K(m), indicating that it acts in an uncompetitive manner. CONCLUSIONS AND IMPLICATIONS The disruption of every stage of NO signal transduction by common CaM antagonists, unrelated to CaM antagonism, cautions against their utility as pharmacological tools. More positively, the compounds exemplify a novel class of sGC inhibitors that, with improved selectivity, may be therapeutically valuable.
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McElroy SP, Drummond RM, Gurney AM. Regulation of store-operated Ca2+ entry in pulmonary artery smooth muscle cells. Cell Calcium 2009; 46:99-106. [DOI: 10.1016/j.ceca.2009.05.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2008] [Revised: 05/05/2009] [Accepted: 05/31/2009] [Indexed: 11/25/2022]
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Harper MT, Sage SO. Is calcium-independent phospholipase A2 required for store-operated calcium entry in human platelets? J Thromb Haemost 2008; 6:1819-21. [PMID: 18680539 DOI: 10.1111/j.1538-7836.2008.03113.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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19
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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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20
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Liao WC, Huang CC, Cheng HH, Wang JL, Lin KL, Cheng JS, Chai KL, Hsu PT, Tsai JY, Fang YC, Lu YC, Chang HT, Huang JK, Chou CT, Jan CR. Effect of calmidazolium on [Ca2+]i and viability in human hepatoma cells. Arch Toxicol 2008; 83:61-8. [DOI: 10.1007/s00204-008-0328-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2008] [Accepted: 06/03/2008] [Indexed: 11/28/2022]
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Abstract
Arachidonic acid (AA), a polyunsaturated fatty acid with four double bonds, has multiple actions on living cells. Many of these effects are mediated by an action of AA or its metabolites on ion channels. During the last 10 years, new types of ion channels, transient receptor potential (TRP) channels, store-operated calcium entry (SOCE) channels and non-SOCE channels have been studied. This review summarizes our current knowledge about the effects of AA on TRP and non-SOCE channels as well as classical ion channels. It aims to distinguish between effects of AA itself and effects of AA metabolites. Lipid mediators are of clinical interest because some of them (for example, leukotrienes) play a role in various diseases, others (such as prostaglandins) are targets for pharmacological therapeutic intervention.
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Redondo PC, Salido GM, Pariente JA, Sage SO, Rosado JA. SERCA2b and 3 play a regulatory role in store-operated calcium entry in human platelets. Cell Signal 2008; 20:337-46. [DOI: 10.1016/j.cellsig.2007.10.019] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2007] [Accepted: 10/18/2007] [Indexed: 11/26/2022]
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Pennington SR, Foster BJ, Hawley SR, Jenkins RE, Zolle O, White MRH, McNamee CJ, Sheterline P, Simpson AWM. Cell shape-dependent Control of Ca2+ influx and cell cycle progression in Swiss 3T3 fibroblasts. J Biol Chem 2007; 282:32112-20. [PMID: 17711856 DOI: 10.1074/jbc.m705067200] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The ability of adherent cells such as fibroblasts to enter the cell cycle and progress to S phase is strictly dependent on the extent to which individual cells can attach to and spread on a substratum. Here we have used microengineered adhesive islands of 22 and 45 mum diameter surrounded by a nonadhesive substratum of polyhydroxyl methacrylate to accurately control the extent to which individual Swiss 3T3 fibroblasts may spread. The effect of cell shape on mitogen-evoked Ca2+ signaling events that accompany entry into the cell cycle was investigated. In unrestricted cells, the mitogens bombesin and fetal calf serum evoked a typical biphasic change in the cytoplasmic free Ca2+ concentration. However, when the spreading of individual cells was restricted, such that progression to S phase was substantially reduced, both bombesin and fetal calf serum caused a rapid transient rise in the cytoplasmic free Ca2+ concentration but failed to elicit the normal sustained influx of Ca2+ that follows Ca2+ release. As expected, restricting cell spreading led to the loss of actin stress fibers and the formation of a ring of cortical actin. Restricting cell shape did not appear to influence mitogen-receptor interactions, nor did it influence the presence of focal adhesions. Because Ca2+ signaling is an essential component of mitogen responses, these findings implicate Ca2+ influx as a necessary component of cell shape-dependent control of the cell cycle.
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Affiliation(s)
- Stephen R Pennington
- Department of Human Anatomy and Cell Biology, School of Biomedical Sciences, University of Liverpool, Sherrington Buildings, Ashton Street, Liverpool L69 3GE, United Kingdom
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Jousset H, Malli R, Girardin N, Graier W, Demaurex N, Frieden M. Evidence for a receptor-activated Ca2+ entry pathway independent from Ca2) store depletion in endothelial cells. Cell Calcium 2007; 43:83-94. [PMID: 17548108 PMCID: PMC6786894 DOI: 10.1016/j.ceca.2007.04.006] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2006] [Revised: 03/28/2007] [Accepted: 04/05/2007] [Indexed: 11/18/2022]
Abstract
Ca(2+) entry in endothelial cells is a key signaling event as it prolongs the Ca(2+) signal activated by a receptor agonist, and thus allows an adequate production of a variety of compounds. The possible routes that lead to Ca(2+) entry in non-excitable cells include the receptor-activated Ca(2+) entry (RACE), which requires the presence of an agonist to be activated, and the store-operated Ca(2+) entry (SOCE) pathway, whose activation requires the depletion of the ER Ca(2+) store. However, the relative importance of these two influx pathways during physiological stimulation is not known. In the present study we experimentally differentiated these two types of influxes and determined under which circumstances they are activated. We show that La(3+) (at 10 microM) is a discriminating compound that efficiently blocks SOCE but is almost without effect on histamine-induced Ca(2+) entry (RACE). In line with this, histamine does not induce massive store depletion when performed in the presence of extracellular Ca(2+). In addition, inhibition of mitochondrial respiration significantly reduces SOCE but modestly affects RACE. Thus, agonist-induced Ca(2+) entry is insensitive to La(3+), and only modestly affected by mitochondrial depolarization. These data shows that agonist relies almost exclusively on RACE for sustained Ca(2+) signaling in endothelial cells.
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Affiliation(s)
- H. Jousset
- Department of Cell Physiology and Metabolism, Geneva Medical Center, 1 rue Michel Servet, 1211 Geneva 4, Switzerland
| | - R. Malli
- Institute of Molecular Biology and Biochemistry, Center of Molecular Medicine, Medical University Graz, 8010 Graz, Austria
| | - N. Girardin
- Department of Cell Physiology and Metabolism, Geneva Medical Center, 1 rue Michel Servet, 1211 Geneva 4, Switzerland
| | - W.F. Graier
- Institute of Molecular Biology and Biochemistry, Center of Molecular Medicine, Medical University Graz, 8010 Graz, Austria
| | - N. Demaurex
- Department of Cell Physiology and Metabolism, Geneva Medical Center, 1 rue Michel Servet, 1211 Geneva 4, Switzerland
| | - M. Frieden
- Department of Cell Physiology and Metabolism, Geneva Medical Center, 1 rue Michel Servet, 1211 Geneva 4, Switzerland
- Corresponding author at: Department of Cell Physiology and Metabolism, University of Geneva Medical School, 1 Michel-Servet, 1211 Geneva 4, Switzerland. Tel.: +41 22 379 5198; fax: +41 22 379 5338. (M. Frieden)
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Bakowski D, Parekh AB. Voltage-dependent Ba2+ permeation through store-operated CRAC channels: implications for channel selectivity. Cell Calcium 2007; 42:333-9. [PMID: 17343911 DOI: 10.1016/j.ceca.2007.01.005] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2006] [Accepted: 01/19/2007] [Indexed: 11/28/2022]
Abstract
Store-operated Ca2+ entry through CRAC channels is a major route for Ca2+ influx in non-excitable cells. Studies on store-operated channel selectivity using fluorescent dyes have found that the channels are impermeable to Ba2+. Furthermore, in such studies, agonists have been reported to increase Ba2+ influx, leading to the conclusion that additional Ca2+ entry pathways (permeable to Ba2+) co-exist with the Ba2+-impermeable store-operated channels. However, patch clamp experiments demonstrate that CRAC channels are permeable to Ba2+. We have addressed this paradox using fluorescence measurements and whole cell patch clamp recordings of ICRAC. In store-depleted cells loaded with fura 2, Ba2+ application results in a slower and smaller rise in fluorescence than is the case with Ca2+. Ba2+, unlike Ca2+, depolarises the membrane potential by approximately 40 mV, due to rapid block of an inwardly rectifying K+ current. Although Ba2+ permeates CRAC channels at very negative potentials in patch clamp recordings, Ba2+ permeation is steeply voltage-dependent. This combination of Ba2+-dependent depolarisation and voltage-dependent Ba2+ permeation accounts for the apparent lack of Ba2+ permeation through store-operated channels seen in fluorescence experiments. Our findings identify major limitations with the use of Ba2+ as a surrogate for Ca2+ in probing Ca2+ entry pathways and raise the possibility that some of the previous reports proposing multiple Ca2+ entry pathways based on Ba2+ entry into fura 2-loaded cells could be explained by voltage-dependent Ba2+ permeation through CRAC channels.
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Affiliation(s)
- Daniel Bakowski
- Department of Physiology, University of Oxford, Parks Road, Oxford OX1 3PT, UK
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Holmes AM, Roderick HL, McDonald F, Bootman MD. Interaction between store-operated and arachidonate-activated calcium entry. Cell Calcium 2007; 41:1-12. [PMID: 16765441 DOI: 10.1016/j.ceca.2006.04.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2005] [Revised: 03/22/2006] [Accepted: 04/12/2006] [Indexed: 11/30/2022]
Abstract
A ubiquitous pathway for cellular Ca(2+) influx involves 'store-operated channels' that respond to depletion of intracellular Ca(2+) pools via an as yet unknown mechanism. Due to its wide-spread expression, store-operated Ca(2+) entry (SOCE) has been considered a principal route for Ca(2+) influx. However, recent evidence has suggested that alternative pathways, activated for example by lipid metabolites, are responsible for physiological Ca(2+) influx. It is not clear if these messenger-activated Ca(2+) entry routes exist in all cells and what interaction they have with SOCE. In the present study we demonstrate that HEK-293 cells and Saos-2 cells express an arachidonic acid (AA)-activated Ca(2+) influx pathway that is distinct from SOCE on the basis of sensitivity to pharmacological blockers and depletion of cellular cholesterol. We examined the functional interaction between SOCE and the arachidonate-triggered Ca(2+) influx (denoted non-SOCE). Both Ca(2+) entry routes could underlie substantial long-lasting Ca(2+) elevations. However, the two pathways could not operate simultaneously. With cells that had an on-going SOCE response, addition of arachidonate gave two profound effects. Firstly, it rapidly inhibited SOCE. Secondly, the mode of Ca(2+) influx switched to the non-SOCE mechanism. Addition of arachidonate to naïve cells resulted in rapid activation of the non-SOCE pathway. However, this Ca(2+) entry route was very slowly engaged if the SOCE pathway was already operative. These data indicate that the SOCE and arachidonate-activated non-SOCE pathways interact in an inhibitory manner. We probed the plausible mechanisms by which these two pathways may communicate.
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Affiliation(s)
- Anthony M Holmes
- The Babraham Institute, Laboratory of Molecular Signalling, Babraham, Cambridge CB2 4AT, UK
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27
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Singaravelu K, Lohr C, Deitmer JW. Regulation of store-operated calcium entry by calcium-independent phospholipase A2 in rat cerebellar astrocytes. J Neurosci 2006; 26:9579-92. [PMID: 16971542 PMCID: PMC6674595 DOI: 10.1523/jneurosci.2604-06.2006] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
We have studied store-operated Ca2+ entry (SOCE) in Bergmann glia and granule cell layer astrocytes in acute brain slices of the rat cerebellum, using the Ca2+-sensitive fluorescent dye Fluo-4 and confocal laser scanning microscopy. Astrocytes were identified by their morphology, location, and their Ca2+ response in K+-free solution. Depletion of Ca2+ stores by cyclopiazonic acid (CPA) (20 microM) induced SOCE in both types of astrocyte. A similar Ca2+ influx was elicited by the calmodulin antagonist calmidazolium (CMZ) (1 microM). The SOCE channel blocker 2-aminoethoxy-diphenylborate (2-APB) (100 microM) and the Ca2+ release-activated channel blocker 3,5-bistrifluoromethyl pyrazole derivative (BTP2) (20 microM) suppressed the CPA- and the CMZ-induced Ca2+ influx. Pretreatment of acute slices with the specific Ca2+-independent phospholipase A2 (iPLA2) inhibitor bromoenol lactone (BEL) (25 microM) blocked the CPA- and the CMZ-induced Ca2+ influx. The lysophospholipid products of iPLA2, lysophosphatidylcholine (250 nM) and lysophosphatidylinositol (250 nM), but not lysophosphatidic acid (250 nM), induced a BTP2- and 2-APB-sensitive, but BEL-insensitive, Ca2+ influx. CPA or CMZ enhanced the BEL-sensitive enzymatic activity of iPLA2 in cerebellar astrocyte culture. Inhibition of iPLA2 expression by specific antisense oligodeoxynucleotide of iPLA2 reduced the SOCE and the Ca2+ store refilling in cultured astrocytes. Spontaneous Ca2+ oscillations in astrocytes in situ were reduced after inhibiting SOCE channels or iPLA2 activity. The results suggest that the depletion of Ca2+ stores activates iPLA2 to open Ca2+ channels in the plasma membrane by the formation of lysophospholipids in astrocytes, presumably to refill the stores and allow normal Ca2+ signaling.
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Affiliation(s)
- Karthika Singaravelu
- Abteilung für Allgemeine Zoologie, Fachbereich Biologie, Technische Universität Kaiserslautern, D-67653 Kaiserslautern, Germany
| | - Christian Lohr
- Abteilung für Allgemeine Zoologie, Fachbereich Biologie, Technische Universität Kaiserslautern, D-67653 Kaiserslautern, Germany
| | - Joachim W. Deitmer
- Abteilung für Allgemeine Zoologie, Fachbereich Biologie, Technische Universität Kaiserslautern, D-67653 Kaiserslautern, Germany
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Caraveo G, van Rossum DB, Patterson RL, Snyder SH, Desiderio S. Action of TFII-I outside the nucleus as an inhibitor of agonist-induced calcium entry. Science 2006; 314:122-5. [PMID: 17023658 DOI: 10.1126/science.1127815] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
TFII-I is a transcription factor and a target of phosphorylation by Bruton's tyrosine kinase. In humans, deletions spanning the TFII-I locus are associated with a cognitive defect, the Williams-Beuren cognitive profile. We report an unanticipated role of TFII-I outside the nucleus as a negative regulator of agonist-induced calcium entry (ACE) that suppresses surface accumulation of TRPC3 (transient receptor potential C3) channels. Inhibition of ACE by TFII-I requires phosphotyrosine residues that engage the SH2 (Src-homology 2) domains of phospholipase C-g (PLC-g) and an interrupted, pleckstrin homology (PH)-like domain that binds the split PH domain of PLC-g. Our observations suggest a model in which TFII-I suppresses ACE by competing with TRPC3 for binding to PLC-g.
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Affiliation(s)
- Gabriela Caraveo
- Department of Molecular Biology and Genetics, Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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Cheek TR, Thorn P. A constitutively active nonselective cation conductance underlies resting Ca2+ influx and secretion in bovine adrenal chromaffin cells. Cell Calcium 2006; 40:309-18. [PMID: 16806464 DOI: 10.1016/j.ceca.2006.04.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2005] [Revised: 02/27/2006] [Accepted: 04/12/2006] [Indexed: 10/24/2022]
Abstract
We have combined fluorimetric measurements of the intracellular free Ca(2+) concentration ([Ca(2+)](i)) with the patch clamp technique, to investigate resting Ca(2+) entry in bovine adrenal chromaffin cells. Perfusion with nominally Ca(2+)-free medium resulted in a rapid, reversible decrease in [Ca(2+)](i), indicating a resting Ca(2+) permeability across the plasma membrane. Simultaneous whole-cell voltage-clamp showed a resting inward current that increased when extracellular Ca(2+) (Ca(2+)(o)) was lowered. This current had a reversal potential of around 0 mV and was carried by monovalent or divalent cations. In Na(+)-free extracellular medium there was a reduction in current amplitude upon removal of Ca(2+)(o), indicating the current can carry Ca(2+). The current was constitutively active and not enhanced by agents that promote Ca(2+)-store depletion such as thapsigargin. Extracellular La(3+) abolished the resting current, reduced resting [Ca(2+)](i) and inhibited basal secretion. Abolishment of resting Ca(2+) influx depleted the inositol 1,4,5-trisphosphate-sensitive Ca(2+) store without affecting the caffeine-sensitive Ca(2+) store. The results indicate the presence of a constitutively active nonselective cation conductance, permeable to both monovalent and divalent cations, that can regulate [Ca(2+)](i), the repletion state of the intracellular Ca(2+) store and the secretory response in resting cells.
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Affiliation(s)
- Timothy R Cheek
- Institute for Cell and Molecular Biosciences, University of Newcastle-upon-Tyne, The Medical School, Framlington Place, Newcastle-upon-Tyne NE2 4HH, UK.
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Moneer Z, Pino I, Taylor E, Broad L, Liu Y, Tovey S, Staali L, Taylor C. Different phospholipase-C-coupled receptors differentially regulate capacitative and non-capacitative Ca2+ entry in A7r5 cells. Biochem J 2005; 389:821-9. [PMID: 15918794 PMCID: PMC1180733 DOI: 10.1042/bj20050145] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Several receptors, including those for AVP (Arg8-vasopressin) and 5-HT (5-hydroxytryptamine), share an ability to stimulate PLC (phospholipase C) and so production of IP3 (inositol 1,4,5-trisphosphate) and DAG (diacylglycerol) in A7r5 vascular smooth muscle cells. Our previous analysis of the effects of AVP on Ca2+ entry [Moneer, Dyer and Taylor (2003) Biochem. J. 370, 439-448] showed that arachidonic acid released from DAG stimulated NO synthase. NO then stimulated an NCCE (non-capacitative Ca2+ entry) pathway, and, via cGMP and protein kinase G, it inhibited CCE (capacitative Ca2+ entry). This reciprocal regulation ensured that, in the presence of AVP, all Ca2+ entry occurred via NCCE to be followed by a transient activation of CCE only when AVP was removed [Moneer and Taylor (2002) Biochem. J. 362, 13-21]. We confirm that, in the presence of AVP, all Ca2+ entry occurs via NCCE, but 5-HT, despite activating PLC and evoking release of Ca2+ from intracellular stores, stimulates Ca2+ entry only via CCE. We conclude that two PLC-coupled receptors differentially regulate CCE and NCCE. We also address evidence that, in some A7r5 cells lines, AVP fails either to stimulate NCCE or inhibit CCE [Brueggemann, Markun, Barakat, Chen and Byron (2005) Biochem. J. 388, 237-244]. Quantitative PCR analysis suggests that these cells predominantly express TRPC1 (transient receptor potential canonical 1), whereas cells in which AVP reciprocally regulates CCE and NCCE express a greater variety of TRPC subtypes (TRPC1=6>2>3).
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Affiliation(s)
- Zahid Moneer
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, U.K
| | - Irene Pino
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, U.K
| | - Emily J. A. Taylor
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, U.K
| | - Lisa M. Broad
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, U.K
| | - Yingjie Liu
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, U.K
| | - Stephen C. Tovey
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, U.K
| | - Leila Staali
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, U.K
| | - Colin W. Taylor
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, U.K
- To whom correspondence should be addressed (email )
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31
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Weirich J, Dumont L, Fleckenstein-Grün G. Contribution of capacitative and non-capacitative Ca2+-entry to M3-receptor-mediated contraction of porcine coronary smooth muscle. Cell Calcium 2005; 38:457-67. [PMID: 16099040 DOI: 10.1016/j.ceca.2005.06.035] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2005] [Revised: 05/14/2005] [Accepted: 06/15/2005] [Indexed: 10/25/2022]
Abstract
We studied the contribution of store-operated or capacitative Ca2+-entry (SOCE or CCE, respectively) through store-operated Ca2+ channels (SOCCs) and the contribution of Ca2+-entry through receptor-operated, non-selective cation channels (ROCCs or NSCCs, respectively), on the M3-receptor-mediated (270 nM Ach) contractile response of porcine coronary smooth muscle strips by means of the respective inhibitors. In the presence of L-VOCC blockade (1 microM verapamil), LOE 908 (inhibition of NSCCs) decreased the contractile response to 75+/-5% (p<0.01, n=6), 2-APB (inhibition of SOCCs) and SK and F 96365 (inhibition of SOCCs and of NSCCs) decreased the response to 45+/-4% (p<0.001, n=10) and to 23+/-2% (p<0.001, n=5), respectively (control: Ach response in the presence of verapamil alone). In the absence of L-VOCC blockade, LOE 908 reduced the Ach-response to 49+/-7% (p<0.001, n=8) and SK and F 96365 to 3+/-2% (p<0.001, n=4) of control, whereas 2-APB transiently increased the response (peak effect: 130+/-11%; p<0.05, n=8). We conclude: (1) the main source of activator Ca2+ during the M3-receptor-mediated contractile response is the Ca2+ influx through L-VOCCs; (2) however, in the presence of L-VOCC blockade, the contractile response is mainly due to Ca2+-entry through SOCCs; (3) NSCCs may be considerably involved in M3-receptor-mediated contraction as they may serve to depolarize the membrane potential and, thus, to open L-VOCCs; (4) in primary tissue of vascular smooth muscle, both, SOCE and Ca2+-entry through NSCCs are activated during M3-receptor stimulation.
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Affiliation(s)
- Jörg Weirich
- Department of Physiology, University Freiburg i. Br., D 79104 Freiburg, Germany
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32
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Luo D, Sun H, Lan X, Xiao R, Han Q. Direct coupling between arachidonic acid-induced Ca2+ release and Ca2+ entry in HEK293 cells. Prostaglandins Other Lipid Mediat 2005; 75:141-51. [PMID: 15789621 DOI: 10.1016/j.prostaglandins.2004.11.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Arachidonic acid (AA) modulates intracellular Ca2+ signaling via Ca2+ release or/and Ca2+ entry. However, the mechanism underlies either process is unknown; nor is it clear as to whether the two processes are mechanistically linked. By using Fura2/AM, we found that AA induced mobilization of internal Ca2+ store and an increment in Ca2+, Mn2+ and Ba2+ influx in HEK293 cells. The AA-mediated Ca2+ signaling was not due to AA metabolites, and insensitive to capacitative Ca2+ entry inhibitors. Interestingly, isotetrandrine and Gd3+ inhibited both AA-induced Ca2+ release and Ca2+ entry in a concentration-dependent manner without affecting Ca2+ discharge caused by carbachol, caffeine, or thapsigargin. Additionally, similar pattern of inhibition was observed with tetracaine treatment. More importantly, the three compounds exhibited almost equal potent inhibition of AA-initiated Ca2+ release as well as Ca2+ influx. Therefore, this study, for the first time, provides evidence for a direct coupling between AA-mediated Ca2+ release and Ca2+ entry.
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Affiliation(s)
- Dali Luo
- Institute of Cardiovascular Science at Health Science Center, Peking University, Beijing 100083, PR China.
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Rychkov GY, Litjens T, Roberts ML, Barritt GJ. Arachidonic acid inhibits the store-operated Ca2+ current in rat liver cells. Biochem J 2005; 385:551-6. [PMID: 15516207 PMCID: PMC1134728 DOI: 10.1042/bj20041604] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Vasopressin and other phospholipase-C-coupled hormones induce oscillations (waves) of [Ca2+]cyt (cytoplasmic Ca2+ concentration) in liver cells. Maintenance of these oscillations requires replenishment of Ca2+ in intracellular stores through Ca2+ inflow across the plasma membrane. While this may be achieved by SOCs (store-operated Ca2+ channels), some studies in other cell types indicate that it is dependent on AA (arachidonic acid)-activated Ca2+ channels. We studied the effects of AA on membrane conductance of rat liver cells using whole-cell patch clamping. We found no evidence that concentrations of AA in the physiological range could activate Ca2+-permeable channels in either H4IIE liver cells or rat hepatocytes. However, AA (1-10 microM) did inhibit (IC50=2.4+/-0.1 microM) Ca2+ inflow through SOCs (ISOC) initiated by intracellular application of Ins(1,4,5)P3 in H4IIE cells. Pre-incubation with AA did not inhibit ISOC development, but decreased maximal amplitude of the current. Iso-tetrandrine, widely used to inhibit receptor-activation of phospholipase A2, and therefore AA release, inhibited ISOC directly in H4IIE cells. It is concluded that (i) in rat liver cells, AA does not activate an AA-regulated Ca2+-permeable channel, but does inhibit SOCs, and (ii) iso-tetrandrine and tetrandrine are effective blockers of CRAC (Ca2+-release-activated Ca2+) channel-like SOCs. These results indicate that AA-activated Ca2+-permeable channels do not contribute to hormone-induced increases or oscillations in [Ca2+]cyt in liver cells. However, AA may be a physiological modulator of Ca2+ inflow in these cells.
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Affiliation(s)
- Grigori Y Rychkov
- School of Molecular and Biomedical Science, University of Adelaide, Adelaide, South Australia 5005, Australia.
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Brown A, Riddoch F, Robson A, Redfern C, Cheek T. Mechanistic and functional changes in Ca2+ entry after retinoic acid-induced differentiation of neuroblastoma cells. Biochem J 2005; 388:941-8. [PMID: 15673285 PMCID: PMC1183475 DOI: 10.1042/bj20042127] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2004] [Accepted: 01/27/2005] [Indexed: 11/17/2022]
Abstract
We have investigated effects of neuronal differentiation on hormone-induced Ca2+ entry. Fura-2 fluorescence measurements of undifferentiated SH-SY5Y neuroblastoma cells, stimulated with methacholine, revealed the presence of voltage-operated Ca2+-permeable, Mn2+-impermeable entry pathways, and at least two voltage-independent Ca2+- and Mn2+-permeable entry pathways, all of which apparently contribute to both peak and plateau phases of the Ca2+ signal. Similar experiments using 9-cis retinoic acid-differentiated cells, however, revealed voltage-operated Ca2+-permeable, Mn2+-impermeable channels, and, more significantly, the absence or down-regulation of the most predominant of the voltage-independent entry pathways. This down-regulated pathway is probably due to CCE (capacitative Ca2+ entry), since thapsigargin also stimulated Ca2+ and Mn2+ entry in undifferentiated but not differentiated cells. The Ca2+ entry components remaining in methacholine-stimulated differentiated cells contributed to only the plateau phase of the Ca2+ signal. We conclude that differentiation of SH-SY5Y cells results in a mechanistic and functional change in hormone-stimulated Ca2+ entry. In undifferentiated cells, voltage-operated Ca2+ channels, CCE and NCCE (non-CCE) pathways are present. Of the voltage-independent pathways, the predominant one appears to be CCE. These pathways contribute to both peak and plateau phases of the Ca2+ signal. In differentiated cells, CCE is either absent or down-regulated, whereas voltage-operated entry and NCCE remain active and contribute to only the plateau phase of the Ca2+ signal.
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Affiliation(s)
- Anna M. Brown
- *Institute for Cell and Molecular Biosciences, The Medical School, University of Newcastle, Framlington Place, Newcastle-upon-Tyne NE2 4HH, U.K
| | - Fiona C. Riddoch
- *Institute for Cell and Molecular Biosciences, The Medical School, University of Newcastle, Framlington Place, Newcastle-upon-Tyne NE2 4HH, U.K
| | - Andrew Robson
- *Institute for Cell and Molecular Biosciences, The Medical School, University of Newcastle, Framlington Place, Newcastle-upon-Tyne NE2 4HH, U.K
| | - Christopher P. F. Redfern
- †Northern Institute for Cancer Research, The Medical School, University of Newcastle, Framlington Place, Newcastle-upon-Tyne NE2 4HH, U.K
| | - Timothy R. Cheek
- *Institute for Cell and Molecular Biosciences, The Medical School, University of Newcastle, Framlington Place, Newcastle-upon-Tyne NE2 4HH, U.K
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