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Takeda Y, Shimayoshi T, Holz GG, Noma A. Modeling analysis of inositol 1,4,5-trisphosphate receptor-mediated Ca2+ mobilization under the control of glucagon-like peptide-1 in mouse pancreatic β-cells. Am J Physiol Cell Physiol 2016; 310:C337-47. [PMID: 26741144 PMCID: PMC4888524 DOI: 10.1152/ajpcell.00234.2015] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Accepted: 11/19/2015] [Indexed: 01/22/2023]
Abstract
Glucagon-like peptide-1 (GLP-1) is an intestinally derived blood glucose-lowering hormone that potentiates glucose-stimulated insulin secretion from pancreatic β-cells. The secretagogue action of GLP-1 is explained, at least in part, by its ability to stimulate cAMP production so that cAMP may facilitate the release of Ca(2+) from inositol trisphosphate receptor (IP3R)-regulated Ca(2+) stores. However, a quantitative model has yet to be provided that explains the molecular mechanisms and dynamic processes linking GLP-1-stimulated cAMP production to Ca(2+) mobilization. Here, we performed simulation studies to investigate how GLP-1 alters the abilities of Ca(2+) and IP3 to act as coagonists at IP3R Ca(2+) release channels. A new dynamic model was constructed based on the Kaftan model, which demonstrates dual steady-state allosteric regulation of the IP3R by Ca(2+) and IP3. Data obtained from β-cells were then analyzed to understand how GLP-1 facilitates IP3R-mediated Ca(2+) mobilization when UV flash photolysis is used to uncage Ca(2+) and IP3 intracellularly. When the dynamic model for IP3R activation was incorporated into a minimal cell model, the Ca(2+) transients and oscillations induced by GLP-1 were successfully reconstructed. Simulation studies indicated that transient and oscillatory responses to GLP-1 were produced by sequential positive and negative feedback regulation due to fast activation and slow inhibition of the IP3R by Ca(2+). The slow rate of Ca(2+)-dependent inhibition was revealed to provide a remarkable contribution to the time course of the decay of cytosolic Ca(2+) transients. It also served to drive and pace Ca(2+) oscillations that are significant when evaluating how GLP-1 stimulates insulin secretion.
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Affiliation(s)
- Yukari Takeda
- Department of Bioinformatics, College of Life Sciences, Ritsumeikan University, Kusatsu City, Japan;
| | - Takao Shimayoshi
- Department of Systems Science, Kyoto University, Kyoto, Japan; and
| | - George G Holz
- Departments of Medicine and Pharmacology, SUNY Upstate Medical University, Syracuse, New York
| | - Akinori Noma
- Department of Bioinformatics, College of Life Sciences, Ritsumeikan University, Kusatsu City, Japan
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2
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Jovic A, Howell B, Cote M, Wade SM, Mehta K, Miyawaki A, Neubig RR, Linderman JJ, Takayama S. Phase-locked signals elucidate circuit architecture of an oscillatory pathway. PLoS Comput Biol 2010; 6:e1001040. [PMID: 21203481 PMCID: PMC3009597 DOI: 10.1371/journal.pcbi.1001040] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2010] [Accepted: 11/27/2010] [Indexed: 12/26/2022] Open
Abstract
This paper introduces the concept of phase-locking analysis of oscillatory cellular signaling systems to elucidate biochemical circuit architecture. Phase-locking is a physical phenomenon that refers to a response mode in which system output is synchronized to a periodic stimulus; in some instances, the number of responses can be fewer than the number of inputs, indicative of skipped beats. While the observation of phase-locking alone is largely independent of detailed mechanism, we find that the properties of phase-locking are useful for discriminating circuit architectures because they reflect not only the activation but also the recovery characteristics of biochemical circuits. Here, this principle is demonstrated for analysis of a G-protein coupled receptor system, the M3 muscarinic receptor-calcium signaling pathway, using microfluidic-mediated periodic chemical stimulation of the M3 receptor with carbachol and real-time imaging of resulting calcium transients. Using this approach we uncovered the potential importance of basal IP3 production, a finding that has important implications on calcium response fidelity to periodic stimulation. Based upon our analysis, we also negated the notion that the Gq-PLC interaction is switch-like, which has a strong influence upon how extracellular signals are filtered and interpreted downstream. Phase-locking analysis is a new and useful tool for model revision and mechanism elucidation; the method complements conventional genetic and chemical tools for analysis of cellular signaling circuitry and should be broadly applicable to other oscillatory pathways. Key to robust discernment of cell circuit architecture is to have as many distinct response features as possible for comparison and evaluation. One under-appreciated characteristic of oscillatory circuits is that under periodic stimulation, these systems will exhibit responses synchronized to this stimulatory input, a phenomenon termed phase-locking. We demonstrate that phase-locked response characteristics vary noticeably depending on circuit activation and recovery properties; these response characteristics thereby provide a unique set of criteria for oscillatory circuit architecture analysis. The concept is validated through experiments on an oscillatory calcium pathway in mammalian cells; the experimental setup allowed us to explore, for the first time, the properties of chemically induced phase-locking of intracellular signals. Observations of this phenomenon were then used to test the predictions of several existing mathematical models of calcium signaling. Most of the models we evaluated were unable to match all our experimental observations, suggesting that current models are missing mechanistic elements in the context of calcium signaling for the cell type and receptor/stimulant tested. The observations of phase-locking further led us to identify one simple mechanistic modification that would account for all the experimental observations. The techniques and methodology presented should be broadly applicable to a variety of biological oscillators.
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Affiliation(s)
- Andreja Jovic
- Biomedical Engineering Department, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Bryan Howell
- Biomedical Engineering Department, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Michelle Cote
- Biomedical Engineering Department, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Susan M. Wade
- Pharmacology Department, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Khamir Mehta
- Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Atsushi Miyawaki
- Laboratory for Cell Function and Dynamics, Advanced Technology Development Center, Brain Science Institute, Wako City, Saitama, Japan
| | - Richard R. Neubig
- Pharmacology Department, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Jennifer J. Linderman
- Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan, United States of America
- * E-mail: (ST); (JJL)
| | - Shuichi Takayama
- Biomedical Engineering Department, University of Michigan, Ann Arbor, Michigan, United States of America
- Macromolecular Science and Engineering Department, University of Michigan, Ann Arbor, Michigan, United States of America
- * E-mail: (ST); (JJL)
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3
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Vasudevan SR, Lewis AM, Chan JW, Machin CL, Sinha D, Galione A, Churchill GC. The calcium-mobilizing messenger nicotinic acid adenine dinucleotide phosphate participates in sperm activation by mediating the acrosome reaction. J Biol Chem 2010; 285:18262-9. [PMID: 20400502 PMCID: PMC2881750 DOI: 10.1074/jbc.m109.087858] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Before a sperm can fertilize an egg it must undergo a final activation step induced by the egg termed the acrosome reaction. During the acrosome reaction a lysosome-related organelle, the acrosome, fuses with the plasma membrane to release hydrolytic enzymes and expose an egg-binding protein. Because NAADP (nicotinic acid adenine dinucleotide phosphate) releases Ca2+ from acidic lysosome-related organelles in other cell types, we investigated a possible role for NAADP in mediating the acrosome reaction. We report that NAADP binds with high affinity to permeabilized sea urchin sperm. Moreover, we used Mn2+ quenching of luminal fura-2 and 45Ca2+ to directly demonstrate NAADP regulation of a cation channel on the acrosome. Additionally, we show that NAADP synthesis occurs through base exchange and is driven by an increase in Ca2+. We propose a new model for acrosome reaction signaling in which Ca2+ influx initiated by egg jelly stimulates NAADP synthesis and that this NAADP acts on its receptor/channel on the acrosome to release Ca2+ to drive acrosomal exocytosis.
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Affiliation(s)
- Sridhar R Vasudevan
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, United Kingdom
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4
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Yangthara B, Mills A, Chatsudthipong V, Tradtrantip L, Verkman AS. Small-molecule vasopressin-2 receptor antagonist identified by a g-protein coupled receptor "pathway" screen. Mol Pharmacol 2007; 72:86-94. [PMID: 17435162 DOI: 10.1124/mol.107.034496] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
G-protein-coupled receptors (GPCRs) such as the vasopressin-2 receptor (V(2)R) are an important class of drug targets. We developed an efficient screen for GPCR-induced cAMP elevation using as read-out cAMP activation of cystic fibrosis transmembrane conductance regulator (CFTR) Cl(-) channels. Fischer rat thyroid cells expressing CFTR and a halide-sensing yellow fluorescent protein (H148Q/I152L) were transfected with V(2)R. Increased cell Cl(-) conductance after agonist-induced cAMP elevation was assayed using a plate reader from cell fluorescence after solution I(-) addition. The Z' factor for the assay was approximately 0.7 with the V(2)R agonist [deamino-Cys1, Val4, d-Arg8]-vasopressin (1 nM) as positive control. Primary screening of 50,000 small molecules yielded a novel, 5-aryl-4-benzoyl-3-hydroxy-1-(2-arylethyl)-2H-pyrrol-2-one class of V(2)R antagonists that are unrelated structurally to known V(2)R antagonists. The most potent compound, V(2)R(inh)-02, which was identified by screening 35 structural analogs, competitively inhibited V(2)R-induced cAMP elevation with K(i) value of approximately 70 nM and fully displaced radiolabeled vasopressin in binding experiments. V(2)R(inh)-02 did not inhibit forskolin or beta(2)-adrenergic receptor-induced cAMP production and was more than 50 times more potent for V(2)R than for V(1a)R. The favorable in vitro properties of the pyrrol-2-one antagonists suggests their potential usefulness in aquaretic applications. The CFTR-linked cAMP assay developed here is applicable for efficient, high-throughput identification of modulators of cAMP-coupled GPCRs.
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Affiliation(s)
- Buranee Yangthara
- Department of Medicine, Cardiovascular Research Institute, University of California, San Francisco, California 94143-0521, USA
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5
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Sandnes D, Nilssen LS, Andersen GO, Viko H, Sjetnan AE, Skomedal T, Osnes JB. Ca2+-dependent elevation of inositol 1,4,5-trisphosphate level induced by freezing or homogenization of tissues and cells. Basic Clin Pharmacol Toxicol 2004; 95:288-94. [PMID: 15569274 DOI: 10.1111/j.1742-7843.2004.t01-1-pto950507.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Various cells and tissues contain high basal levels of inositol 1,4,5-trisphosphate, raising questions about the functional significance of inositol 1,4,5-trisphosphate in some tissues such as the heart. We used intact tissue and isolated cells from heart and liver of adult rats to examine if different fixation procedures might artificially elevate the level of inositol 1,4,5-trisphosphate. The basal level of inositol 1,4,5-trisphosphate in intact, freeze-clamped cardiac tissue from adult rats was 10 times higher than in isolated, non-frozen cardiomyocytes, while freeze-clamped liver contained approximately 4 times higher inositol 1,4,5-trisphosphate levels than isolated, non-frozen hepatocytes. Stimulation with norepinephrine induced a significant increase in the inositol 1,4,5-trisphosphate level in isolated cardiomyocytes, whereas no significant increase was observed in freeze-clamped cardiac tissue. Freezing of isolated cardiomyocytes or hepatocytes before extraction increased basal inositol 1,4,5-trisphosphate levels 3 times. In cellular homogenates prepared in the presence of EGTA and stored at 4 degrees , readdition of calcium resulted in a time-dependent increase in inositol 1,4,5-trisphosphate mass and a decrease in the mass of phosphatidylinositol 4,5-bisphosphate (PIP(2)). The reaction was essentially complete within 30 sec. in homogenates from cardiomyocytes, while PIP(2) hydrolysis was slower in hepatocyte homogenates. Perfusion of intact rat hearts with EGTA present during the last 2 min. of perfusion, followed by freeze-clamping, resulted in basal inositol 1,4,5-trisphosphate levels comparable to those in isolated cardiomyocytes, and norepinephrine stimulation increased inositol 1,4,5-trisphosphate mass by approximately 80%. The presence of EGTA did not significantly affect PIP(2) levels in perfused hearts. The results suggest that freezing or homogenization of intact tissue and isolated cells may result in Ca(2+)-dependent activation of phospholipase C, leading to high basal inositol 1,4,5-trisphosphate levels that may mask agonist-induced changes.
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Affiliation(s)
- Dagny Sandnes
- Department of Pharmacology, Medical Faculty, University of Oslo, P.O. Box 1057 Blindern, N-0316 Oslo, Norway
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6
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Abstract
The number of technologies that enable high-throughput functional screening of G-protein-coupled receptors has expanded markedly over the past 5 years. Consequently, choosing the most appropriate technology can be a daunting task, particularly for Gi- or Gs-coupled receptors. The most common systems for cyclic AMP detection are reviewed, highlighting the practical and theoretical aspects that are important in their application to high-throughput screening. Current technologies can do the job, but it is likely that the future may require development of technologies that provide even greater biological information.
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Affiliation(s)
- Christine Williams
- Hit Discovery Group, Pfizer Global Research and Development, Ramsgate Road, Sandwich, Kent CT13 9NJ, UK.
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7
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Lemon G, Gibson WG, Bennett MR. Metabotropic receptor activation, desensitization and sequestration-I: modelling calcium and inositol 1,4,5-trisphosphate dynamics following receptor activation. J Theor Biol 2003; 223:93-111. [PMID: 12782119 DOI: 10.1016/s0022-5193(03)00079-1] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
A mathematical account is given of the processes governing the time courses of calcium ions (Ca2+), inositol 1,4,5-trisphosphate (IP(3)) and phosphatidylinositol 4,5-bisphosphate (PIP(2)) in single cells following the application of external agonist to metabotropic receptors. A model is constructed that incorporates the regulation of metabotropic receptor activity, the G-protein cascade and the Ca2+ dynamics in the cytosol. It is subsequently used to reproduce observations on the extent of desensitization and sequestration of the P(2)Y(2) receptor following its activation by uridine triphosphate (UTP). The theory predicts the dependence on agonist concentration of the change in the number of receptors in the membrane as well as the time course of disappearance of receptors from the plasmalemma, upon exposure to agonist. In addition, the extent of activation and desensitization of the receptor, using the calcium transients in cells initiated by exposure to agonist, is also predicted. Model predictions show the significance of membrane PIP(2) depletion and resupply on the time course of IP(3) and Ca2+ levels. Results of the modelling also reveal the importance of receptor recycling and PIP(2) resupply for maintaining Ca2+ and IP(3) levels during sustained application of agonist.
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Affiliation(s)
- G Lemon
- The School of Mathematics and Statistics, University of Sydney, NSW 2006, Australia
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8
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Lemon G, Gibson WG, Bennett MR. Metabotropic receptor activation, desensitization and sequestration-II: modelling the dynamics of the pleckstrin homology domain. J Theor Biol 2003; 223:113-29. [PMID: 12782120 DOI: 10.1016/s0022-5193(03)00080-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Recent observations have been made regarding the generation of inositol 1,4,5-trisphosphate (IP(3)), using chimeras of green fluorescent protein and the pleckstrin homology domain of phospholipase C-delta. In this paper a model is presented giving the quantitative relations between the green fluorescent protein-pleckstrin homology domain (GFP-PHD) construct and membrane phosphatidylinositol 4,5-bisphosphate (PIP(2)) levels as well as the concentration of IP(3), the product of hydrolysis of PIP(2). The model can correctly reproduce the dependence of cytosolic GFP-PHD fluorescence on IP(3) concentration. This model extends a previous one (Metabotropic receptor activation, desensitization and sequestration-I: modelling calcium and inositol 1,4,5-trisphosphate dynamics following receptor activation, in this issue) dealing with the processes governing the production of IP(3) and the subsequent calcium (Ca2+) changes in cells following activation of metabotropic receptors. This model is applied to the case of purinergic P(2)Y(2) receptor activation in Madin-Darby Canine Kidney (MDCK) cells with adenosine triphosphate (ATP) (Science 284 (1999) 1527). It is shown that it can correctly reproduce the dependence of GFP-PHD fluorescence on the concentration of P(2)Y(2) receptor ligand, as well as the temporal changes of GFP-PHD fluorescence following application of ligand.
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Affiliation(s)
- G Lemon
- The School of Mathematics and Statistics, University of Sydney, NSW 2006, Australia
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9
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Churchill GC, O'Neill JS, Masgrau R, Patel S, Thomas JM, Genazzani AA, Galione A. Sperm deliver a new second messenger: NAADP. Curr Biol 2003; 13:125-8. [PMID: 12546785 DOI: 10.1016/s0960-9822(03)00002-2] [Citation(s) in RCA: 139] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
NAADP is a highly potent mobilizer of Ca(2+), which in turn triggers Ca(2+)-induced Ca(2+) release pathways in a wide range of species. Nevertheless, NAADP is not presently classified as a second messenger because it has not been shown to increase in response to a physiological stimulus. We now report a dramatic increase in NAADP during sea urchin egg fertilization that was largely due to production in sperm upon contacting egg jelly. The NAADP bolus plays a physiological role upon delivery to the egg based on its ability to induce a cortical flash, a depolarization-induced activation of L-type Ca(2+) channels. Moreover, the sperm-induced cortical flash was eliminated in eggs desensitized to NAADP. We conclude that an NAADP increase plays a physiologically relevant role during fertilization and provides the first conclusive demonstration that NAADP is a genuine second messenger.
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Affiliation(s)
- Grant C Churchill
- Department of Pharmacology, University of Oxford, Mansfield Road, OX1 3QT, Oxford, United Kingdom.
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10
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Cheley S, Gu LQ, Bayley H. Stochastic sensing of nanomolar inositol 1,4,5-trisphosphate with an engineered pore. CHEMISTRY & BIOLOGY 2002; 9:829-38. [PMID: 12144927 DOI: 10.1016/s1074-5521(02)00172-2] [Citation(s) in RCA: 121] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The introduction of a ring of arginine residues near the constriction in the transmembrane beta barrel of the staphylococcal alpha-hemolysin heptamer yielded a pore that could be almost completely blocked by phosphate anions at pH 7.5. Block did not occur with other oxyanions, including nitrate, sulfate, perchlorate, and citrate. Based on this finding, additional pores were engineered with high affinities for important cell signaling molecules, such as the Ca(2+)-mobilizing second messenger inositol 1,4,5-trisphosphate (IP(3)), that contain phosphate groups. One of these engineered pores, P(RR-2), provides a ring of fourteen arginines that project into the lumen of the transmembrane barrel. Remarkably, P(RR-2) bound IP(3) with low nanomolar affinity while failing to bind another second messenger, adenosine 3', 5'-cyclic monophosphate (cAMP). The engineered alpha-hemolysin pores may be useful as components of stochastic sensors for cell signaling molecules.
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Affiliation(s)
- Stephen Cheley
- Department of Medical Biochemistry and Genetics, The Texas A & M University System Health Science Center, College Station, TX 77843, USA.
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11
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Kohlmeier KA, Burns J, Reiner PB, Semba K. Substance P in the descending cholinergic projection to REM sleep-induction regions of the rat pontine reticular formation: anatomical and electrophysiological analyses. Eur J Neurosci 2002; 15:176-96. [PMID: 11860518 DOI: 10.1046/j.0953-816x.2001.01829.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Release of acetylcholine within the pontine reticular formation (PRF) from the axon terminals of mesopontine cholinergic neurons has long been hypothesized to play an important role in rapid eye movement (REM) sleep generation. As some of these cholinergic neurons are known to contain substance P (SP), we used anatomical, electrophysiological and pharmacological techniques to characterize this projection in the rat. Double immunofluorescence demonstrated that 16% of all cholinergic neurons within the mesopontine tegmentum contained SP; this percentage increased to 27% in its caudal regions. When double immunofluorescence was combined with retrograde tracing techniques, it was observed that up to 11% of all SP-containing cholinergic neurons project to the PRF. Whole-cell patch-clamp recordings from in vitro brainstem slices revealed that SP administration depolarized or evoked an inward current in a dose-dependent manner in all PRF neurons examined, and that these effects were antagonized by a SP antagonist. The amplitude of the SP-induced inward current varied with changes in the Na+ concentration, did not reverse at the calculated K+ or Cl- equilibrium potentials, and was not attenuated in the presence of tetrodotoxin, low Ca2+ concentration or caesium ions. These data suggest that activation of a tetrodotoxin-insensitive cation channel(s) permeable to Na+ is responsible for a SP-induced inward current at resting membrane potentials. The depolarizing actions of SP appeared to be primarily due to activation of the adenylate cyclase pathway, and were additive with cholinergic receptor activation even at maximal concentrations. These data indicate that SP is colocalized in a subpopulation of mesopontine tegmental cholinergic neurons projecting to REM sleep-induction regions of the PRF, and that actions of these two neuroactive substances on PRF neurons are additive. If SP is coreleased with acetylcholine, the additive actions of the two neurotransmitters might heighten the excitability of postsynaptic PRF neurons and ensure the initiation and maintenance of REM sleep.
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Affiliation(s)
- Kristi A Kohlmeier
- Kinsmen Laboratory of Neurological Research, Department of Psychiatry, School of Medicine, University of British Columbia, Vancouver, B.C., V6T 1Z3 Canada
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12
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Abstract
Capacitative Ca2+ entry exists in rat glioma C6 cells; however, how the information of depletion of Ca2+ in intracellular stores transmits to the plasma membrane is unknown. In the present study, we examined whether Ca2+ influx factor (CIF) causes capacitative Ca2+ entry in C6 cells. CIF was extracted from non-treated (Non-CIF), bombesin-treated (BBS-CIF) and thapsigargin-treated (TG-CIF) C6 cells by a reverse-phase silica cartridge. The addition of BBS-CIF and TG-CIF gradually increased cytoplasmic Ca2+ concentration ([Ca2+]i) but Non-CIF did not increase [Ca2+]i. Neither BBS-CIF nor TG-CIF elevated [Ca2+]i in the absence of extracellular Ca2+. Gd3+ inhibited the increase in [Ca2+]i induced by BBS-CIF and TG-CIF. Genistein abolished an elevation of [Ca2+]i induced by BBS-CIF and TG-CIF. BBS-CIF and TG-CIF did not increase inositol 1,4,5-trisphosphate accumulation. The results suggest that capacitative Ca2+ entry is caused by CIF in rat glioma C6 cells.
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Affiliation(s)
- H Takemura
- Department of Pharmacology, School of Medicine, Sapporo Medical University, Japan
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13
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Cheung WT, Yeung SY, Yiu AK, Ip TM, Wan DC, Luk SK, Ho WK. Characterization of a functional AT1A angiotensin receptor in pancreatoma AR4-2J cells. Peptides 1999; 20:829-36. [PMID: 10477083 DOI: 10.1016/s0196-9781(99)00069-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Functional angiotensin receptors were characterized in the rat pancreatic acinar cell line AR4-2J. Angiotensin II stimulated a dose-dependent release of amylase and production of inositol phosphates. Results of high-performance liquid chromatography separation of inositol phosphates indicated that angiotensin stimulated the rapid accumulation of inositol 1,3,4-trisphosphate. Angiotensin II and angiotensin III were at least an order of magnitude more potent than angiotensin I in the stimulation of amylase release. The angiotensin II-stimulated amylase release was blocked by losartan, a selective AT1 angiotensin antagonist. The selective AT2 angiotensin receptor ligands CGP42112 did not alter angiotensin II-stimulated amylase released. However, CGP42112 stimulated amylase release at micromolar concentrations with a potency similar to angiotensin I. Analysis of mRNA expression by reverse transcription polymerase chain reaction suggested that AT1A was the predominant type-I angiotensin receptor expressed in the AR4-2J cells.
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Affiliation(s)
- W T Cheung
- Department of Biochemistry, Faculty of Medicine, The Chinese University of Hong Kong.
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14
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Luzzi V, Sims CE, Soughayer JS, Allbritton NL. The physiologic concentration of inositol 1,4,5-trisphosphate in the oocytes of Xenopus laevis. J Biol Chem 1998; 273:28657-62. [PMID: 9786859 DOI: 10.1074/jbc.273.44.28657] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
To measure the concentration of inositol 1,4,5-trisphosphate ([IP3]) in small regions of single Xenopus oocytes, a biological detector cell was combined with capillary electrophoresis. This method is 10, 000 times more sensitive than all existing assays enabling subcellular measurement of [IP3] in Xenopus oocytes. Upon addition of lysophosphatidic acid to an oocyte, [IP3] increased from 40 to 650 nM within 2 min. IP3 concentrations as high as 1.8 microM were measured after activation with lysophosphatidic acid, suggesting that the physiologic concentration of IP3 ranges from the tens of nanomolar to a few micromolar in Xenopus oocytes. Since the IP3 receptor in Xenopus oocytes is nearly identical to the type I receptor of mammalian cells, the range of [IP3] in most mammalian cells is likely to be similar to that in the oocyte. By selecting or engineering the appropriate detector cell, this strategy should be applicable to cyclic adenosine diphosphate ribose and nicotinic acid adenine dinucleotide phosphate, and to the discovery of new Ca2+-releasing second messengers.
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Affiliation(s)
- V Luzzi
- Department of Physiology and Biophysics University of California, Irvine, California 92697-4560, USA
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15
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Fukuhara S, Shimizu M, Matsushima H, Mukai H, Munekata E. Signaling pathways via NK1 receptors and their desensitization in an AR42J cell line. Peptides 1998; 19:1349-57. [PMID: 9809648 DOI: 10.1016/s0196-9781(98)00078-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Substance P (SP) has been shown to induce phosphatidylinositol (PI) hydrolysis and Ca2+ mobilization in AR42J cells. In this study, we confirmed the expression of NK1 but not NK2 or NK3 receptors in this cell line, and further investigated signaling pathways via NK1 receptors and their desensitization. The activation of NK1 receptors by SP affected neither basal cyclic AMP level nor cyclic AMP accumulation induced by secretin and forskolin, although it stimulated PI hydrolysis. Furthermore, SP induced Ca2+ mobilization even in the absence of extracellular Ca2+, though maximal response was reduced. U73122, a phospholipase C (PLC) inhibitor, nearly abolished Ca2+ response to SP. In addition, SP-induced Ca2+ signaling and PI hydrolysis rapidly desensitized following short exposure to SP, which did not affect the Ca2+ amount in intracellular Ca2+ stores or Ca2+ responses to carbachol and gastrin releasing peptide-10. These findings suggested that NK1 receptors do not couple to adenylate cyclase, although they induce PI response, and that NK1 receptors induce both intracellular Ca2+ release and Ca2+ influx through PLC activation. Ca2+ signaling and PI hydrolysis through NK1 receptors desensitized rapidly after the stimulation, maybe dependent on the modification of NK1 receptors.
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Affiliation(s)
- S Fukuhara
- Institute of Applied Biochemistry, University of Tsukuba, Ibaraki, Japan
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16
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Patel S, Morris SA, Adkins CE, O'Beirne G, Taylor CW. Ca2+-independent inhibition of inositol trisphosphate receptors by calmodulin: redistribution of calmodulin as a possible means of regulating Ca2+ mobilization. Proc Natl Acad Sci U S A 1997; 94:11627-32. [PMID: 9326661 PMCID: PMC23558 DOI: 10.1073/pnas.94.21.11627] [Citation(s) in RCA: 89] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The interactions between calmodulin, inositol 1,4,5-trisphosphate (InsP3), and pure cerebellar InsP3 receptors were characterized by using a scintillation proximity assay. In the absence of Ca2+, 125I-labeled calmodulin reversibly bound to multiple sites on InsP3 receptors and Ca2+ increased the binding by 190% +/- 10%; the half-maximal effect occurred when the Ca2+ concentration was 184 +/- 14 nM. In the absence of Ca2+, calmodulin caused a reversible, concentration-dependent (IC50 = 3.1 +/- 0.2 microM) inhibition of [3H]InsP3 binding by decreasing the affinity of the receptor for InsP3. This effect was similar at all Ca2+ concentrations, indicating that the site through which calmodulin inhibits InsP3 binding has similar affinities for calmodulin and Ca2+-calmodulin. Calmodulin (10 microM) inhibited the Ca2+ release from cerebellar microsomes evoked by submaximal, but not by maximal, concentrations of InsP3. Tonic inhibition of InsP3 receptors by the high concentrations of calmodulin within cerebellar Purkinje cells may account for their relative insensitivity to InsP3 and limit spontaneous activation of InsP3 receptors in the dendritic spines. Inhibition of InsP3 receptors by calmodulin at all cytosolic Ca2+ concentrations, together with the known redistribution of neuronal calmodulin evoked by protein kinases and Ca2+, suggests that calmodulin may also allow both feedback control of InsP3 receptors and integration of inputs from other signaling pathways.
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Affiliation(s)
- S Patel
- Department of Pharmacology, Tennis Court Road, Cambridge CB2 1QJ, England, United Kingdom
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17
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Holzer P, Holzer-Petsche U. Tachykinins in the gut. Part II. Roles in neural excitation, secretion and inflammation. Pharmacol Ther 1997; 73:219-63. [PMID: 9175156 DOI: 10.1016/s0163-7258(96)00196-9] [Citation(s) in RCA: 180] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The preprotachykinin-A gene-derived peptides substance (substance P; SP) and neurokinin (NK) A are expressed in intrinsic enteric neurons, which supply all layers of the gut, and extrinsic primary afferent nerve fibers, which innervate primarily the arterial vascular system. The actions of tachykinins on the digestive effector systems are mediated by three different types of tachykinin receptor, termed NK1, NK2 and NK3 receptors. Within the enteric nervous system, SP and NKA are likely to mediate, or comediate, slow synaptic transmission and to modulate neuronal excitability via stimulation of NK3 and NK1 receptors. In the intestinal mucosa, tachykinins cause net secretion of fluid and electrolytes, and it appears as if SP and NKA play a messenger role in intramural secretory reflex pathways. Secretory processes in the salivary glands and pancreas are likewise influenced by tachykinins. The gastrointestinal arterial system may be dilated or constricted by tachykinins, whereas constriction and an increase in the vascular permeability are the only effects seen in the venous system. Various gastrointestinal disorders are associated with distinct changes in the tachykinin system, and there is increasing evidence that tachykinins participate in the hypersecretory, vascular and immunological disturbances associated with infection and inflammatory bowel disease. In a therapeutic perspective, it would seem conceivable that tachykinin antagonists could be exploited as antidiarrheal, antiinflammatory and antinociceptive drugs.
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Affiliation(s)
- P Holzer
- Department of Experimental and Clinical Pharmacology, University of Graz, Austria
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18
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Xu X, Zeng W, Muallem S. Regulation of the inositol 1,4,5-trisphosphate-activated Ca2+ channel by activation of G proteins. J Biol Chem 1996; 271:11737-44. [PMID: 8662624 DOI: 10.1074/jbc.271.20.11737] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Streptolysin O-permeable pancreatic acini were used to study the regulation of the inositol 1,4,5-trisphosphate (IP3)-activated Ca2+ channel (IPACC) by agonists and antagonists. Measurements of the apparent affinity for IP3 (KappIP3) showed that the IPACC is dynamically controlled during cell stimulation and inhibition, i.e. agonists decreased and antagonists increased KappIP3. KappIP3 was also independently regulated by thimerosal, Ca2+ content of the stores, the incubation temperature, activation of protein kinases, and inhibition of protein phosphatases, but none of these mechanisms contributed to the regulation by agonists and antagonists. Incubating the cells with low concentration of GTPgammaS or AIF3 reproduced the effect of the agonist on KappIP3. Moreover, low [GTPgammaS] allowed activation of the IPACC by agonists at basal levels of IP3 and markedly impaired channel inactivation by antagonists. Channel sensitization by GTPgammaS also restored the ability of thimerosal to mobilize Ca2+ from internal stores with no change in cellular IP3 levels. The combination of low [GTPgammaS] and thimerosal locked the channel in an open, antagonist-insensitive state. All modulatory effects of GTPgammaS are independent of phospholipase C activation and IP3 production. We propose that the dynamic regulation of the IPACC by a G protein-dependent mechanism can play a major role in triggering and maintaining Ca2+ oscillations at low agonist concentrations when minimal or no changes in IP3 level take place.
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Affiliation(s)
- X Xu
- Department of Physiology, University of Texas Southwestern Medical School, Dallas 75235, USA
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19
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Bold RJ, Ishizuka J, Townsend CM, Thompson JC. Secretin potentiates cholecystokinin-stimulated amylase release by AR4-2J cells via a stimulation of phospholipase C. J Cell Physiol 1995; 165:172-6. [PMID: 7559798 DOI: 10.1002/jcp.1041650120] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Alterations in the activity of phospholipase C (PLC) are thought to be the primary intracellular events leading to pancreatic acinar cell exocytosis of zymogen granules. When multiple hormones, each of which may stimulate different signal transduction pathways, bind to cell surface receptors, the cell must integrate these signals into a common response through communication (cross-talk) among intracellular second messengers. We show that cholecystokinin (CCK) induces amylase secretion from AR4-2J pancreatic acinar cells via stimulation of PLC activity. Secretin indirectly stimulated the PLC pathway through cross-talk of the activated cAMP pathway to potentiate the CCK-stimulated amylase secretion. Therefore, secretin potentiated the acinar cell secretory response to CCK by cAMP-mediated cross-talk with the PLC signal transduction pathway.
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Affiliation(s)
- R J Bold
- Department of Surgery, University of Texas Medical Branch, Galveston 77555, USA
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20
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Singh AK, Jiang Y. Quantitative chromatographic analysis of inositol phospholipids and related compounds. JOURNAL OF CHROMATOGRAPHY. B, BIOMEDICAL APPLICATIONS 1995; 671:255-80. [PMID: 8520695 DOI: 10.1016/0378-4347(94)00558-m] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The metabolism of phospholipids and the mobilization of second messengers such as inositol-1,4,5-trisphosphate, 1,2-diacylglycerol (DAG) and arachidonic acid (AA) from phospholipids is commonly studied by radiolabelling phospholipids with [3H]myo-inositol or [32P]ATP and measuring the incorporation of radioactivity in different phospholipids or their hydrolysis products. However, for the radiolabelling method to accurately reflect changes in the compound's mass, it is essential that the tissue is labelled to isotopic equilibrium which is difficult to achieve. To circumvent the disadvantages of the radiolabelling method, several analytical procedures have been developed for the mass analysis of phospholipids and inositolphosphates (IPs). Quantitation of the mass or the radiolabelling of phospholipids is a complex multi-step procedure that involves quantitative isolation of phospholipids, fractionation of individual phospholipids and either determination of radioactivity in each component or the measurement of their mass. Phospholipids, DAG and AA are extracted from tissue sample with organic solvents such as chloroform-methanol (2:1) containing HCl or formic acid. The extract is separated by TLC, cartridge-column chromatography or HPLC on a reversed-phase column. Phospholipids are quantitated by measuring inorganic phosphate, absorption at 200 nm or mass spectrometry. Inositol phosphates are extracted with perchloric acid or trichloroacetic acid and separated by ion-exchange cartridge-column or HPLC with an ion-exchange column. IPs are quantitated by measuring inorganic phosphate or by using enzymatic reaction, metal-dye coupling, NMR or mass spectrometry.
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Affiliation(s)
- A K Singh
- Department of Veterinary Diagnostic Medicine, College of Veterinary Medicine, University of Minnesota, St. Paul 55108, USA
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21
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Baron CB, Ozaki S, Watanabe Y, Hirata M, LaBelle EF, Coburn RF. Inositol 1,4,5-trisphosphate binding to porcine tracheal smooth muscle aldolase. J Biol Chem 1995; 270:20459-65. [PMID: 7657622 DOI: 10.1074/jbc.270.35.20459] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
A cytoskeletal fraction of porcine tracheal smooth muscle (PTSM) was found to contain > 90% of total cellular aldolase (fructose 1,6-bisphosphate aldolase, EC 4.1.2.13) activity. PTSM aldolase was purified by DEAE and inositol 1,4,5-trisphosphate (Ins(1,4,5)P3) affinity chromatography and found to react with an antibody directed against human aldolase C, but not anti-aldolase A and B. The molecular mass of native aldolase was about 138 kDa (on Sephacryl S-300); SDS-denatured enzyme was 35 kDa (comigrated with rabbit skeletal muscle aldolase). Total cellular aldolase tetramer (aldolase4) content was 34.5 pmol/100 nmol lipid P(i). Ins(1,4,5)P3) binding activity coeluted with aldolase during Sephacryl 300, DEAE, and Ins(1,4,5)P3 affinity chromatography. Ins(1,4,5)P3 bound to purified aldolase (at 0 degree C) in a dose-dependent manner over the range [Ins(1,4,5)P3] 20 nM to 20 microM, with maximal binding of 1 mol of Ins(1,4,5)P3/mol aldolase4 and a Kd of 12-14 microM. Fru(1,6)P2 and Fru(2,6)P2 displaced bound Ins(1,4,5)P3) with a 50% inhibition at 30 and 170 microM, respectively. Ins(1,3,4)P3 (20 microM) and glyceraldehyde 3-phosphate (2 mM) were also potent inhibitors of Ins(1,4,5)P3 binding, but not inositol 4-phosphate or inositol 1,4-bisphosphate (20 microM each). Aldolase-bound Ins(1,4,5)P3 may play a role in phospholipase C-independent increases in free [Ins(1,4,5)P3].
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Affiliation(s)
- C B Baron
- Department of Physiology, University of Pennsylvania School of Medicine, Philadelphia 19104, USA
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22
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Chappell MC, Jacobsen DW, Tallant EA. Characterization of angiotensin II receptor subtypes in pancreatic acinar AR42J cells. Peptides 1995; 16:741-7. [PMID: 7479311 DOI: 10.1016/0196-9781(95)00044-k] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The AR42J acinar cell line was characterized as a potential cellular model to assess the functional aspects of an exocrine pancreatic angiotensin system. Binding studies revealed that the AR42J cells express high affinity angiotensin II binding sites (Kd = 0.73 +/- 0.06 nM; Bmax = 292 +/- 15 fmol/mg protein, n = 3). Competition studies established that these cells, similar to the intact pancreas, express predominantly the AT2 receptor subtype. The AT2-selective antagonists CGP 42112A, PD 123177, and PD 123319 competed for the majority of angiotensin II binding. However, 10-15% of the angiotensin II binding sites were competed for by the AT1-selective antagonist DuP 753 (Losartan). Affinity labeling of these binding sites with [125I]angiotensin II followed by SDS gel electrophoresis under reducing conditions revealed a single band comprising a molecular mass of 108,000 Da. Competition with unlabeled angiotensin II or the AT2 antagonist, but not the AT1 antagonist, abolished the 108,000-Da band. In intact cells, angiotensin II caused a rapid increase in intracellular calcium (Ca2+) using Fura-2 as a Ca2+ indicator. Pretreatment of the cells with the AT1 antagonist DuP 753 completely inhibited the angiotensin II-induced rise in Ca2+; however, the AT2 antagonists CGP 42112A and PD 123177 were ineffective in blocking the Ca2+ increase. These results demonstrate that this pancreatic acinar cell line expresses both AT2 and AT1 angiotensin II receptor subtypes. The AT1 receptor is coupled to the mobilization of Ca(2+)--a characteristic shared by AT1 receptors in other tissues.
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Affiliation(s)
- M C Chappell
- Hypertension Center, Bowman Gray School of Medicine, Winston-Salem, NC 27157, USA
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23
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Seva C, Scemama JL, Pradayrol L, Sarfati PD, Vaysse N. Coupling of pancreatic gastrin/cholecystokinin-B (G/CCKB) receptors to phospholipase C and protein kinase C in AR4-2J tumoral cells. REGULATORY PEPTIDES 1994; 52:31-8. [PMID: 7972929 DOI: 10.1016/0167-0115(94)90018-3] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Gastrin and cholecystokinin (CCK) have proven trophic effects on the gut. We have previously demonstrated that these peptides stimulate an early event in cellular proliferation, namely ornithine decarboxylase activity (ODC), in a rat exocrine pancreatic cell line AR4-2J. Furthermore, this effect is mediated through a G/CCKB receptor. Thus, in the present study we sought to examine the signal transduction mechanisms linked to the G/CCKB receptor occupancy. Both gastrin and CCK induced a rapid (maximum at 40 s) increase in inositol triphosphates (InsP3) and diacylglycerol (DAG) formation in a dose-dependent manner (EC50 = 5.6 nM) that quickly returned to baseline. Although InsP3 levels remained at baseline, DAG levels demonstrated a second gradual increase that was maximal at 15 min. CCK/gastrin efficiency to stimulate DAG and InsP3 formation (EC50 = 5.6 nM) could be correlated to the G/CCKB receptor occupancy, suggesting a coupling of this receptor to phospholipase C. To examine the involvement of protein kinase C (PKC) activation in the increase in ODC activity, we stimulated the AR4-2J cells with the phorbol ester TPA and observed an increase in ODC activity with a maximal effect at 100 nM. TPA stimulation of ODC activity was completely abolished by the PKC inhibitor staurosporine (50 nM). However, 50 nM staurosporine inhibited only 65% of the gastrin and CCK induced increase in ODC activity suggesting that a portion of the G/CCKB receptor-mediated increase in ODC activity is PKC independent.
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Affiliation(s)
- C Seva
- Institute National de la Santé et de la Recherche Médical U.151, CHU Rangueil, Toulouse, France
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24
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Foster PS, Hogan SP, Hansbro PM, O'Brien R, Potter BV, Ozaki S, Denborough MA. The metabolism of D-myo-inositol 1,4,5-trisphosphate and D-myo-inositol 1,3,4,5-tetrakisphosphate by porcine skeletal muscle. EUROPEAN JOURNAL OF BIOCHEMISTRY 1994; 222:955-64. [PMID: 8026506 DOI: 10.1111/j.1432-1033.1994.tb18946.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
In soluble and particulate extracts from muscle D-myo-inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] and D-myo-inositol 1,3,4,5-tetrakisphosphate [Ins(1,3,4,5)P4] are metabolised stepwise to inositol. Ins(1,4,5)P3 is rapidly dephosphorylated to D-myo-inositol 1,4-bisphosphate then to D-myo-inositol 4-phosphate and finally inositol. In soluble extracts Ins(1,3,4,5)P4 is dephosphorylated to D-myo-inositol 1,3,4-trisphosphate then sequentially to D-myo-inositol 3,4-bisphosphate, D-myo-inositol 3-phosphate and inositol, while in particulate extracts D-myo-inositol 1,3-bisphosphate is the predominant inositol bisphosphate formed. Dephosphorylation of these inositol polyphosphates is Mg2+ dependent and inhibited by D-2,3-bisphosphoglyceric acid. Ins(1,4,5)P3 is also phosphorylated to form Ins(1,3,4,5)P4 in soluble extracts by Ins(1,4,5)P3 3-kinase. Ins(1,4,5)P3 3-kinase activity is Mg2+ and ATP dependent and is stimulated by Ca2+ and calmodulin. Particulate (sarcotubular) inositol polyphosphate 5-phosphatase (5-phosphatase) is found in membranes which are intimately involved in excitation-contraction coupling and the generation of the primary Ca2+ signal of muscle cells. Particulate 5-phosphatase had the highest specific activity in the transverse-tubule membrane, when compared to the terminal cisternae and longitudinal-tubule membranes of the sarcoplasmic reticulum. Particulate Ins(1,3,4,5)P4-3-phosphatase activity was also detected after fractionation of solubilised sarcotubular membranes by DEAE-Sephacel. Particulate 5-phosphatase activity was purified 25,600-fold to a specific activity of 25.6 mumol Ins(1,4,5)P3 hydrolysed.min-1.mg protein-1, after DEAE-Sephacel and novel affinity chromatography using D-2,3-bisphosphoglycerate/agarose and Sepharose-4B-immobilised Ins(1,4,5)P3-analog matrices. Purified particulate 5-phosphatase had apparent Km of 46.3 microM and 1.9 microM and Vmax of 115 and 0.046 mumol substrate hydrolysed.min-1.mg protein-1, for Ins(1,4,5)P3 and Ins(1,3,4,5)P4, respectively. In contrast, purified soluble type I 5-phosphatase had apparent Km of 8.9 microM and 1.1 microM and Vmax of 3.55 and 0.13 mumol substrate hydrolysed.min-1.mg protein-1, for Ins(1,4,5P3 and Ins(1,3,4,5)P4, respectively. As in other cells, muscle 5-phosphatases have a lower affinity, but a higher capacity to metabolise Ins(1,4,5)P3 than Ins(1,3,4,5)P4. Soluble type I 5-phosphatase may have a functional role in the metabolism of both inositol polyphosphates, while particulate 5-phosphatase may primarily metabolise Ins(1,4,5)P3. Purified Ins(1,4,5)P3 3-kinase had an apparent Km of 0.42 microM and a Vmax of 4.12 nmol Ins(1,4,5)P3 phosphorylated.min-1.mg protein-1. The profile of inositol polyphosphate metabolism in muscle is similar to that reported in other tissues.(ABSTRACT TRUNCATED AT 400 WORDS)
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Affiliation(s)
- P S Foster
- Division of Biochemistry and Molecular Biology, John Curtin School of Medical Research, Australian National University, Canberra
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25
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Marmy N, Durand-Arczynska W, Durand J. Agonist-induced production of inositol phosphates in human airway smooth muscle cells in culture. ACTA ACUST UNITED AC 1994; 86:185-94. [PMID: 1343604 DOI: 10.1016/0928-4257(92)90005-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Smooth muscle cells (SMC) from human bronchi were isolated by elastase treatment, subcultured, and characterized by their positive reaction with a monoclonal antibody against alpha-smooth muscle actin (alpha SMA). In each cell line tested, at least 95% of the cells were positively stained. The functional properties of these cells were examined by measuring the metabolism of inositol phosphates (IPs). For that purpose, cells were incubated for 3 days before reaching confluency in the presence of myo-[3H]inositol in order to label the phosphoinositide pool, and the various [3H]IPs were separated by HPLC on a SAX column with a phosphate gradient. IP1 isomers were separated in three peaks; IP2, IP3, IP4, IP5 and IP6 (phytic acid) were each eluted as single peaks. The identity of the [3H]peaks was verified with corresponding [3H]IP standards. The accumulation of [3H]IPs was measured by incubating cells up to 30 min in the presence of 10 mM LiCl, with or without a bronchoconstrictor agent (carbachol, histamine, PGF2 alpha). Histamine, 10(-4) M, elicited a four times larger IP accumulation than carbachol, 10(-4) M, and than PGF2 alpha, 5 10(-5) M. Dose-response curves were established for histamine and carbachol in the range 10(-7)-10(-4) M. At 10(-7) M, carbachol was more effective than histamine in stimulating the IP metabolism. Atropine blocked the response to carbachol, and diphenhydramine inhibited the effect of histamine, indicating the specificity of the response to the agonists. These results indicate that cultured human bronchial SMC are a suitable preparation for studying physiological aspects of membrane transduction in the airways.
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Affiliation(s)
- N Marmy
- Institut de Physiologie, Fribourg, Switzerland
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26
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27
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Tsunoda Y. Receptor-operated Ca2+ signaling and crosstalk in stimulus secretion coupling. BIOCHIMICA ET BIOPHYSICA ACTA 1993; 1154:105-56. [PMID: 8218335 DOI: 10.1016/0304-4157(93)90008-c] [Citation(s) in RCA: 53] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
In the cells of higher eukaryotic organisms, there are several messenger pathways of intracellular signal transduction, such as the inositol 1,4,5-trisphosphate/Ca2+ signal, voltage-dependent and -independent Ca2+ channels, adenylate cyclase/cyclic adenosine 3',5'-monophosphate, guanylate cyclase/cyclic guanosine 3',5'-monophosphate, diacylglycerol/protein kinase C, and growth factors/tyrosine kinase/tyrosine phosphatase. These pathways are present in different cell types and impinge on each other for the modulation of the cell function. Ca2+ is one of the most ubiquitous intracellular messengers mediating transcellular communication in a wide variety of cell types. Over the last decades it has become clear that the activation of many types of cells is accompanied by an increase in cytosolic free Ca2+ concentration ([Ca2+]i) that is thought to play an important part in the sequence of events occurring during cell activation. The Ca2+ signal can be divided into two categories: receptor- and voltage-operated Ca2+ signal. This review describes and integrates some recent views of receptor-operated Ca2+ signaling and crosstalk in the context of stimulus-secretion coupling.
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Affiliation(s)
- Y Tsunoda
- Department of Faculty Science, Hokkaido University, Sapporo, Japan
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28
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Woodcock EA, Anderson KE, Land SL. Lyophilization can generate artifacts in chromatographic profiles of inositol phosphates. JOURNAL OF CHROMATOGRAPHY 1993; 619:121-6. [PMID: 8245150 DOI: 10.1016/0378-4347(93)80454-c] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Lyophilized extracts of [3H]inositol-labelled rat heart or renal tubule preparations were found to contain unidentified 3H-labelled compounds in addition to the inositol phosphates. The appearance of these labelled substances was caused by the presence in the extracts of compounds which bound [3H]inositol when lyophilized together with it. These studies demonstrate a previously undescribed source of [3H]inositol-labelled compounds which can complicate chromatographic profiles of inositol phosphates. These problems can be overcome either by not lyophilizing the samples or by lyophilizing in the presence of 0.3 M urea, which prevents the association with [3H]inositol and does not interfere with the chromatography.
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Affiliation(s)
- E A Woodcock
- Cellular Biochemistry Laboratory, Baker Medical Research Institute, Prahran, Australia
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29
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Pahl C, Novak I. Effect of vasoactive intestinal peptide, carbachol and other agonists on the membrane voltage of pancreatic duct cells. Pflugers Arch 1993; 424:315-20. [PMID: 8414920 DOI: 10.1007/bf00384358] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The regulation of pancreatic exocrine secretion involves hormonal, neural and neurohormonal components. Many agonists are known to be effective in pancreatic acinar cells, but less is known about the ducts. Therefore, we wanted to investigate the influence of various agonists on isolated perfused pancreatic ducts and, as a physiological response, we measured the basolateral membrane voltage of the duct cells (Vbl) with microelectrodes. Pancreatic ducts were dissected from pancreas of normal rats and bathed in a HCO(3-)(-containing solution. Under control conditions, the average Vbl was between -50 and -70 mV. Vasoactive intestinal peptide (VIP) and carbachol (CCH) reversibly depolarized Vbl when applied to the bath. VIP (9 x 10(-9) mol/l) depolarized Vbl from -72 +/- 3 mV to -53 +/- 3 mV (n = 20) and CCH (10(-5) mol/l) from -62 +/- 3 to -35 +/- 4 mV (n = 10). Furthermore, a decrease of the Cl- concentration in the lumen led to an increase of VIP-induced depolarization of Vbl, suggesting that a luminal Cl- conductance was increased. Cholecystokinin (CCK, 10(-10)-10(-7) mol/l) and bombesin (10(-8), 10(-5) mol/l), which stimulate pancreatic exocrine secretion in acini or whole glands, showed no significant effect on Vbl of the duct cells tested in our preparation (n = 7, 6). Neurotensin (10(-8) mol/l) had a marked depolarizing effect in two out of ten cases; Vbl depolarized from about -65 mV to -29 mV and the effect was reversible. Substance P (2 x 10(-7) mol/l), alone or in combination with secretin, had no effect on Vbl of the tested duct cells (n = 11).(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- C Pahl
- Physiologisches Institut, Albert-Ludwigs-Universität, Freiburg, Germany
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30
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Marmy N, Mottas J, Durand J. Signal transduction in smooth muscle cells from human airways. RESPIRATION PHYSIOLOGY 1993; 91:295-306. [PMID: 8469852 DOI: 10.1016/0034-5687(93)90107-l] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The aim of this study deals with the post-receptor events involved in the response of cultured smooth muscle (SMC) from human bronchi to various agonists of the contraction. [3H]inositol phosphates (IPs) were isolated by high performance liquid chromatography (HPLC) and intracellular Ca2+ concentration ([Ca2+]i) was determined with the Fura-2 fluorescence technique. Following 5 sec stimulation with histamine, an elevation of several [3H]IPs, in particular [3H]1,4-IP2, [3H]1,4,5-IP3 and [3H]1,3,4,5-IP4, above the control values was observed. Following an incubation of 10 or 15 sec with histamine, the content of [3H]1,4,5-IP3 declined towards its basal value, while the amount of metabolites ([3H]4-IP, [3H]1,4-IP2, [3H]1,3,4-IP3) increased with time; [3H]1,3,4,5-IP4 varied little between 5 and 10 sec and decreased at 15 sec. SMC responded also to carbachol and to prostaglandin F2 alpha (PGF2 alpha) by an enhanced production of [3H]IPs, whereas neurokinin A (NKA) had no effect on the turnover of [3H]IPs. Histamine, carbachol and PGF2 alpha evoked a transient elevation in [Ca2+]i, followed by a sustained increase. The duration of the transient elevation appeared similar to that of the increase in [3H]1,4,5-IP3. These results suggest that the 'phospholipase C-1,4,5-IP3-Ca2+ release' signalling pathway is involved in the physiological response of human airway SMC to histamine, carbachol and PGF2 alpha.
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Affiliation(s)
- N Marmy
- Institut de Physiologie, Fribourg, Switzerland
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31
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Measurement of Inositol 1,4,5-Trisphosphate, Inositol 1,3,4,5-Tetrakisphosphate, and Phosphatidylinositol 4,5-Bisphosphate in Brain. ACTA ACUST UNITED AC 1993. [DOI: 10.1016/b978-0-12-185285-6.50027-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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32
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Glennon M, Bird G, Takemura H, Thastrup O, Leslie B, Putney J. In situ imaging of agonist-sensitive calcium pools in AR4-2J pancreatoma cells. Evidence for an agonist- and inositol 1,4,5-trisphosphate-sensitive calcium pool in or closely associated with the nuclear envelope. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(19)74078-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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33
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Oliver K, Buller R, Hughes P, Putney J, Palumbo G. Inhibition of agonist-induced activation of phospholipase C following poxvirus infection. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(19)74011-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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34
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Singh AK. Quantitative analysis of inositol lipids and inositol phosphates in synaptosomes and microvessels by column chromatography: comparison of the mass analysis and the radiolabelling methods. JOURNAL OF CHROMATOGRAPHY 1992; 581:1-10. [PMID: 1429990 DOI: 10.1016/0378-4347(92)80441-r] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Chromatographic methods that measure both the mass and the radiolabelling of various inositol lipids and inositol phosphates in tissues have been developed. The mass of phosphatidylinositol (PtdIns), phosphatidylinositol-4-monophosphate [PtdIns(4)P] and phosphatidylinositol-4,5-bisphosphate [PtdIns(4,5)P2] was quantitated by measuring the inorganic phosphate, whereas inositol monophosphate (IP), inositol bisphosphate (IP2), inositol trisphosphate (IP3) and inositol tetrakisphosphate (IP4) were quantitated by using an enzymic method. The radiolabelling of various inositol lipids and inositol phosphates was determined by incubating the tissue samples with [3H]myo-inositol, separating individual inositol lipids and inositol phosphates, and measuring the radioactivity in each compound. Although the mass analysis method was sensitive enough to measure low levels of inositol lipids or inositol phosphates, the method was laborious and time-consuming. Compared with the enzymic method, the radiolabelling method was simple and fast, but it gave variable results. This study demonstrated differences in inositol lipid and inositol phosphate levels by radiolabelling and mass measurements, and agonist-stimulated phosphatidylinositol turnover of synaptosomes versus the blood-brain barrier as represented by microvessels. Although the mass of PtdIns, PtdIns(4)P and PtdIns(4,5)P2 was comparable in synaptosomes and microvessels, the incorporation of [3H]myo-inositol into phosphorylated PtdIns in microvessels was less than that in synaptosomes.
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Affiliation(s)
- A K Singh
- Department of Veterinary Diagnostic Medicine, College of Veterinary Medicine, University of Minnesota, St. Paul 55108
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35
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The interconversion of inositol 1,3,4,5,6-pentakisphosphate and inositol tetrakisphosphates in AR4-2J cells. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(19)36642-6] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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36
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Mitsuhashi M, Ohashi Y, Shichijo S, Christian C, Sudduth-Klinger J, Harrowe G, Payan DG. Multiple intracellular signaling pathways of the neuropeptide substance P receptor. J Neurosci Res 1992; 32:437-43. [PMID: 1279191 DOI: 10.1002/jnr.490320315] [Citation(s) in RCA: 61] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The rat substance P (SP) receptor cDNA has been transfected into cultured rat KNRK cells, and a stable cell line expressing functional SP receptors established. Upon stimulation with SP, these cells responded by simultaneously activating two signaling pathways: the mobilization of intracellular Ca2+ and the raising of cyclic adenosine triphosphate (cAMP) levels. Both Ca2+ and cAMP responses were elicited in a similar dose-dependent manner with half maximal concentrations of approximately 5 x 10(-10) M. Following ionomycin treatment SP-dependent Ca2+ responses were abolished, whereas cAMP responses were preserved. Forskolin eliminated the SP-dependent cAMP elevation, however, the SP-induced Ca2+ mobilization remained unchanged. Furthermore, treatment with phorbol esters had no significant effect on either of the two SP-induced responses. Thus it appears that the SP receptor is capable of independently activating Ca2+ mobilization and cAMP pathways. These results may provide new insights for further understanding the diverse activities of SP in various systems in vitro and in vivo.
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Affiliation(s)
- M Mitsuhashi
- Division of Medical Sciences, Hitachi Chemical Research Center, Irvine, CA 92715
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37
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Sasakawa N, Nakaki T, Kashima R, Kanba S, Kato R. Stimulus-induced accumulation of inositol tetrakis-, pentakis-, and hexakisphosphates in N1E-115 neuroblastoma cells. J Neurochem 1992; 58:2116-23. [PMID: 1573394 DOI: 10.1111/j.1471-4159.1992.tb10953.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
When [3H]inositol-prelabelled N1E-115 cells were stimulated with carbamylcholine (CCh) (100 microM), high K+ (60 mM), and prostaglandin E1 (PGE1) (10 microM), a transient increase in [3H]inositol pentakisphosphate (InsP5) accumulation was observed. The accumulation reached its maximum level at 15 s and had declined to the basal level at 2 min. CCh, high K+, and PGE1 also caused accumulations of [3H]inositol 1,4,5-trisphosphate [Ins(1,4,5)P3], [3H]inositol 1,3,4,6-tetrakisphosphate [Ins(1,3,4,6)P4], and [3H]inositol hexakisphosphate (InsP6). Muscarine and CCh induced accumulations of [3H]Ins(1,4,5)P3, [3H]-Ins(1,3,4,6)P4, [3H]InsP5, and [3H]InsP6 with a similar potency and exerted these maximal effects at 100 microM, whereas nicotine failed to do so at 1 mM. With a slower time course, CCh, high K+, and PGE1 caused accumulations of [3H]-inositol 1,3,4-trisphosphate [Ins(1,3,4)P3] and [3H]inositol 1,3,4,5-tetrakisphosphate [Ins(1,3,4,5)P4]. In an N1E-115 cell homogenate, [3H]Ins(1,4,5)P3, [3H]Ins(1,3,4,5)P4, and [3H]Ins(1,3,4)P3 were converted to [3H]InsP5 through [3H]-Ins(1,3,4,6)P4. The above results indicate that Ins(1,3,4,6)P4, InsP5, and InsP6 are rapidly formed by several kinds of stimulants in N1E-115 cells.
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Affiliation(s)
- N Sasakawa
- Department of Pharmacology, Keio University School of Medicine, Tokyo, Japan
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38
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Bird GS, Takemura H, Thastrup O, Putney JW, Menniti FS. Mechanisms of activated Ca2+ entry in the rat pancreatoma cell line, AR4-2J. Cell Calcium 1992; 13:49-58. [PMID: 1371721 DOI: 10.1016/0143-4160(92)90029-r] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The characteristics of Ca2+ entry activated by surface receptor agonists and membrane depolarization were studied in the rat pancreatoma cell line, AR4-2J. Ca2+ mobilization activated by substance P, bombesin, or muscarinic receptor stimulation was found to involve both Ca2+ release and entry. In addition, depolarization of the surface membrane of AR4-2J cells with elevated concentrations of K+ activated Ca2+ entry. Ca2+ entry induced by membrane depolarization was inhibited by the L-channel antagonist, nimodipine, while that due to surface receptor agonists was not inhibited by this agent. The microsomal Ca(2+)-ATPase inhibitor, thapsigargin, caused both depletion of the agonist-sensitive intracellular Ca2+ pool and sustained Ca2+ influx indistinguishable from that produced by bombesin or methacholine. These results confirm that, unlike the pancreatic acinar cells from which they are presumably derived, AR4-2J cells express voltage-sensitive, dihydropyridine-inhibitable Ca2+ channels. However, in contrast to previous reports with this cell line, in the AR4-2J cells in use in our laboratory, and under our experimental conditions, surface receptor agonists (including substance P) do not cause Ca2+ influx through voltage-sensitive Ca2+ channels. Instead, we conclude that agonist-activated Ca2+ mobilization is initiated by (1,4,5)IP3-mediated intracellular Ca2+ release and that Ca2+ influx is regulated primarily, if not exclusively, by the state of depletion of the (1,4,5)IP3-sensitive intracellular Ca2+ pool.
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Affiliation(s)
- G S Bird
- Calcium Regulation Section, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina
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39
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Sillence DJ, Downes CP. Lithium treatment of affective disorders: effects of lithium on the inositol phospholipid and cyclic AMP signalling pathways. BIOCHIMICA ET BIOPHYSICA ACTA 1992; 1138:46-52. [PMID: 1310626 DOI: 10.1016/0925-4439(92)90150-l] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The effects of lithium (Li+) on the adenylyl cyclase and inositol phospholipid receptor signalling pathways were compared directly in noradrenergic and carbachol stimulated rat brain cortical tissue slices. Li+ was a comparatively weak inhibitor of noradrenaline-stimulated cyclic AMP accumulation with an IC50 of approx. 20 mM. By contrast, half-maximal effects of Li+ on inositol monophosphate (InsP) accumulation in [3H]inositol labelled tissue slices occurred at about 1 mM. A similar IC50 for Li+ of about 1 mM was also obtained for noradrenaline-stimulated accumulation of CMP-phosphatidate (CMPPA), a sensitive indicator of intracellular inositol depletion, in tissue slices that had been prelabelled with [3H]cytidine. The effect of myo-inositol (inositol) depletion on the prolonged activity of phosphoinositidase C (PIC) was examined in carbachol-stimulated cortical slices using a novel mass assay for InsP. Exposure to a maximal dose of carbachol for 30 min in the presence of 5 mM Li+ caused a 10-fold increase in the level of radioactivity associated with the InsP fraction, but only a 2-fold increase in InsP mass. During prolonged incubations in the presence of both carbachol and Li+ the accumulation of InsP mass was enhanced if 30 mM inositol was included in the medium. The results are compatible with the inositol depletion hypothesis of Li+ action but do not support the concept that adenylyl cyclase or guanine nucleotide dependent proteins represent therapeutically relevant targets of this drug.
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Affiliation(s)
- D J Sillence
- Department of Biochemistry, University of Dundee Medical Sciences Institute, U.K
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40
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Abstract
Biochemical membrane alterations appearing during the process of chemical carcinogenesis are described. Emphasis is put on membrane composition, structure, and biogenesis. In this presentation the knowledge gained from experimental studies of liver and skin in the process of cancer development is acknowledged. Important biochemical changes have been reported in lipid composition, fatty acid saturation, constitutional enzyme expression, receptor turnover and oligomerization. Functional consequences of the altered membrane structure is discussed within the concepts of regulation of cell proliferation, regulation of membrane receptor expression, redox control, signal transduction, drug metabolism, and multidrug resistance. Data from malignant tumours and normal tissue are addressed to evaluate the importance of the alterations for the process and for the eventual malignant transformation.
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Affiliation(s)
- L C Eriksson
- Karolinska Institute, Department of Pathology, Huddinge University Hospital, Sweden
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41
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Fisher SK, Landon RE. Identification of multiple phosphoinositide-linked receptors on human SK-N-MC neuroepithelioma cells. J Neurochem 1991; 57:1599-608. [PMID: 1681032 DOI: 10.1111/j.1471-4159.1991.tb06357.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The biochemical and pharmacological characteristics of receptor-stimulated phosphoinositide (PPI) hydrolysis in human SK-N-MC neuroepithelioma cells have been examined. Of 11 ligands tested, the addition of four, i.e., norepinephrine, oxotremorine-M, endothelin-1, and ATP, each resulted in an increased release (three- to eightfold) of inositol phosphates from [3H]inositol-prelabeled cells. Agonist-stimulated PPI turnover was sustained for at least 30 min and required the addition of Ca2+ for full effect. An increased release of inositol phosphates could also be elicited by the addition of the Ca2+ ionophore, ionomycin. All four agonists enhanced the release of radiolabeled inositol mono- and bisphosphates, inositol 1,3,4-trisphosphate, and inositol tetrakisphosphate. Increases in inositol 1,4,5-trisphosphate were smaller and only consistently observed in the presence of norepinephrine or oxotremorine-M. Norepinephrine-stimulated PPI turnover was potently inhibited by prazosin, WB-4101, and 5-methylurapidil (Ki less than 2.5 nM), but was relatively insensitive to chlorethylclonidine pretreatment. This pharmacological profile is consistent with the involvement of an alpha 1A-receptor subtype. The presence of an M1 muscarinic cholinergic receptor is also indicated, because pirenzepine blocked oxotremorine-M-stimulated inositol phosphate release (Ki = 35 nM) with a 30-fold greater potency than the M2-selective antagonist, AF-DX 116. Of the three endothelins tested, only the addition of endothelin-1 and endothelin-2 promoted PPI hydrolysis, whereas endothelin-3 was essentially inactive. A P2 nucleotide receptor of broad agonist specificity is also present on these cells and activates PPI turnover in the absence of a generalized increase in plasma membrane permeability. These results indicate that SK-N-MC cells express at least four PPI-linked receptors. Because the functional coupling of three of these receptors, i.e., alpha 1A-adrenergic, endothelin, and P2 nucleotide, has not been extensively characterized previously in neural tissues, the SK-N-MC cell line may provide a useful model system for studies of these receptors and their regulation.
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Affiliation(s)
- S K Fisher
- Neuroscience Laboratory, University of Michigan, Ann Arbor 48104-1687
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42
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Smith JP, Kramer ST, Cheung JY. Effects of cholecystokinin on cytosolic calcium in human pancreatic cancer cells. REGULATORY PEPTIDES 1991; 36:299-310. [PMID: 1805301 DOI: 10.1016/0167-0115(91)90064-n] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Cholecystokinin (CCK) has been shown to increase cytosolic calcium and stimulate enzyme release from pancreatic acinar cells and a rat acinar cell line, AR42J. CCK is also trophic to normal pancreas and pancreatic cancer; however, the cellular mechanisms which regulate CCK-stimulated growth are unknown. The effect of CCK on intracellular calcium was evaluated in four human pancreatic cancer cell lines known to grow in response to CCK but not secrete enzymes (SW-1990, MIA PaCa-2, BXPC-3 and PANC-1) and a rat acinar cell line (AR42J) shown to secrete enzymes but not grow with CCK. By using single cell fluorescence microscopy in fura-2 loaded cells, intracellular calcium [Ca2+]i was measured. After obtaining baseline fluorescent cell images, synthetic CCK-octapeptide (CCK8) was added to the cells and images of cell fluorescence captured. [Ca2+]i of the rat acinar cells increased (603%) over the baseline within the first minute after the addition of CCK (4.10(-13) M to 4.10(-10) M) in 77% of cells tested. In contrast [Ca2+]i failed to significantly change in the human cancer cells treated with CCK. To further localize the defect in hormone signal transduction in cancer cells, cells were suspended in low calcium media and the plasma membranes were selectively permeabilized with digitonin. Media free calcium concentration was continuously monitored by fura-2 fluorescence. Addition of inositol 1,4,5-trisphosphate (IP3) resulted in a marked increase in medium calcium concentration indicating IP3 was capable of releasing calcium from intracellular stores in both the AR42J rat acinar cell line and in the human pancreas cancer cell lines. In conclusion, CCK does not increase cytosolic calcium in human pancreatic cancer cells in contrast to rat acinar cells although all contain IP3-sensitive intracellular Ca2+ pools. Our results suggest that growth promoting and secretory effects of CCK on pancreatic cells may occur via two independent signalling pathways.
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Affiliation(s)
- J P Smith
- Department of Medicine, Milton S. Hershey Medical Center, Pennsylvania State University, Hershey 17033
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43
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Putney JW, Bird GS, Horstman DA, Hughes AR, Menniti FS, Nogimori K, Obie J, Oliver KG, Sugiya H, Takemura H. Role of inositol phosphates in the actions of substance P on NK1 receptors in exocrine gland cells. Ann N Y Acad Sci 1991; 632:94-102. [PMID: 1719914 DOI: 10.1111/j.1749-6632.1991.tb33097.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- J W Putney
- Calcium Regulation Section, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709
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44
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Mattingly R, Stephens L, Irvine R, Garrison J. Effects of transformation with the v-src oncogene on inositol phosphate metabolism in rat-1 fibroblasts. D-myo-inositol 1,4,5,6-tetrakisphosphate is increased in v-src-transformed rat-1 fibroblasts and can be synthesized from D-myo-inositol 1,3,4-trisphosphate in cytosolic extracts. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)98597-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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45
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Kroegel C, Chilvers ER, Giembycz MA, Challiss RA, Barnes PJ. Platelet-activating factor stimulates a rapid accumulation of inositol (1,4,5)trisphosphate in guinea pig eosinophils: relationship to calcium mobilization and degranulation. J Allergy Clin Immunol 1991; 88:114-24. [PMID: 2071775 DOI: 10.1016/0091-6749(91)90308-b] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The effect of platelet-activating factor (PAF) on inositol (1,4,5)trisphosphate (Ins[1,4,5]P3) mass, calcium mobilization, and the release of granule enzymes was studied on guinea pig peritoneal eosinophils (EOSs). PAF evoked a concentration-dependent accumulation of Ins(1,4,5)P3 with a drug concentration that elicits 50% of the maximum attainable response (EC50) of 10 nmol/L; the production of this second messenger was maximal at 1 mumol/L of PAF. Kinetic analysis of PAF (1 mumol/L)-induced Ins(1,4,5)P3 accumulation demonstrated it to be transient with a 3.8-fold increase over resting levels observed at 5 seconds. Thereafter, the level of Ins(1,4,5)P3 declined, returning to vehicle-treated levels 60 seconds after PAF challenge. Lyso-PAF, the inactive precursor and metabolite of PAF, was inactive at all concentrations examined. PAF also induced a rapid, concentration-dependent (EC50, 12 nmol/L) rise in the cytosolic-free calcium concentration ([Ca++]i) in fura 2-AM-loaded EOSs that was transient, peaking after the maximum increase in Ins(1,4,5)P3 mass was observed. A highly significant positive correlation was found between the peak increase in Ins(1,4,5)P3 and the peak rise in [Ca++]i. Functionally, PAF evoked a concentration-dependent release of granule constituents from both the small (arylsulfatase B; EC50, 3 nmol/L) and specific (EOS peroxidase; EC50, 2.7 nmol/L) granules that lagged, temporally, behind both Ins(1,4,5)P3 accumulation and the rise in [Ca++]i. Both the biochemical and functional effects of PAF examined in this study were antagonized by WEB 2086 (300 nmol/L), a selective PAF receptor-blocking drug. It is concluded that stimulus (PAF)-response coupling in guinea pig peritoneal EOSs may involve the receptor-mediated formation of Ins(1,4,5)P3 and subsequent release of intracellularly stored Ca++. This sequence of events may link PAF receptor activation to Ca(++)-dependent cellular responses, such as degranulation.
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Affiliation(s)
- C Kroegel
- Department of Thoracic Medicine, National Heart & Lung Institute, Royal Brompton and National Heart and Lung Hospital, London, England
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46
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Ecay TW, Valentich JD. Chloride secretagogues stimulate inositol phosphate formation in shark rectal gland tubules cultured in suspension. J Cell Physiol 1991; 146:407-16. [PMID: 1827124 DOI: 10.1002/jcp.1041460311] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Neuroendocrine activation of transepithelial chloride secretion by shark rectal gland cells is associated with increases in cellular cAMP, cGMP, and free calcium concentrations. We report here on the effects of several chloride secretagogues on inositol phosphate formation in cultured rectal gland tubules. Vasoactive intestinal peptide (VIP), atriopeptin (AP), and ionomycin increase the total inositol phosphate levels of cultured tubules, as measured by ion exchange chromatography. Forskolin, a potent chloride secretagogue, has no effect on inositol phosphate formation. The uptake of 3H-myo-inositol into phospholipids is very slow, preventing the detection of increased levels of inositol trisphosphate. However, significant increases in inositol monophosphate (IP1) and inositol biphosphate (IP2) were measured. The time course of VIP- and AP-stimulated IP1 and IP2 formation is similar to the effects of these agents on the short-circuit current responses of rectal gland monolayer cultures. In addition, aluminum fluoride, an artificial activator of guanine nucleotide-binding proteins, stimulates IP1 and IP2 formation. We conclude that rectal gland cells contain VIP and AP receptors coupled to the activation of phospholipase C. Coupling may be mediated by G-proteins. Receptor-stimulated increases in inositol phospholipid metabolism is one mechanism leading to increased intracellular free calcium concentrations, an important regulatory event in the activation of transepithelial chloride secretion by shark rectal gland epithelial cells.
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Affiliation(s)
- T W Ecay
- Department of Physiology and Cell Biology, University of Texas Medical School, Houston 77225
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47
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Verjans B, Erneux C, Raspe E, Dumont JE. Kinetics of inositol 1,4,5-trisphosphate and inositol 1,3,4,5-tetrakisphosphate generation in dog-thyroid primary cultured cells stimulated by carbachol. EUROPEAN JOURNAL OF BIOCHEMISTRY 1991; 196:43-9. [PMID: 2001706 DOI: 10.1111/j.1432-1033.1991.tb15783.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The action of carbachol on the generation of inositol trisphosphate and tetrakisphosphate isomers was investigated in dog-thyroid primary cultured cells radiolabelled with [3H]inositol. The separation of the inositol phosphate isomers was performed by reverse-phase high pressure liquid chromatography. The structure of inositol phosphates co-eluting with inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] and inositol 1,3,4,5-tetrakisphosphate [Ins(1,3,4,5)P4] standards was determined by enzymatic degradation using a purified Ins(1,4,5)P3/Ins(1,3,4,5)P4 5-phosphatase. The data indicate that Ins(1,3,4,5)P4 was the only [3H]inositol phosphate which co-eluted with a [32P]Ins(1,3,4,5)P4 standard, whereas 80% of the [3H]InsP3 co-eluting with an Ins(1,4,5)P3 standard was actually this isomer. In the presence of Li+, carbachol led to rapid increases in [3H]Ins(1,4,5)P4. The level of Ins(1,4,5)P3 reached a peak at 200% of the control after 5-10 s of stimulation and fell to a plateau that remained slightly elevated for 2 min. The level of Ins(1,3,4,5)P4 reached its maximum at 20s. The level of inositol 1,3,4-trisphosphate [Ins(1,3,4)P3] increased continuously for 2 min after the addition of carbachol. Inositol-phosphate generation was also investigated under different pharmacological conditions. Li+ largely increased the level of Ins(1,3,4)P3 but had no effect on Ins(1,4,5)P3 and Ins(1,3,4,5)P4. Forskolin, which stimulates dog-thyroid adenylate cyclase and cyclic-AMP accumulation, had no effect on the generation of inositol phosphates. The absence of extracellular Ca2+ largely decreased the level of Ins(1,3,4,5)P4 as expected considering the Ca2(+)-calmodulin sensitivity of the Ins(1,4,5)P3 3-kinase. Staurosporine, an inhibitor of protein kinase C, increased the levels of Ins(1,4,5)P3, Ins(1,3,4,5)P4 and Ins(1,3,4)P3. This supports a negative feedback control of diacyglycerol on Ins(1,4,5)P3 generation.
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Affiliation(s)
- B Verjans
- Institute of Interdisciplinary Research (IRIBHN), School of Medicine, Free University of Brussels (ULB), Belgium
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48
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Nahorski SR, John Challiss R. Modulation of receptor-mediated inositol phospholipid breakdown in the brain. Neurochem Int 1991. [DOI: 10.1016/0197-0186(91)90002-u] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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49
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Abstract
Inositol 1,4,5-trisphosphate (Ins(1,4,5)P3) is a soluble intracellular messenger formed rapidly after activation of a variety of cell-surface receptors that stimulate phosphoinositidase C activity. The initial response to Ins(1,4,5)P3 is a rapid Ca2+ efflux from nonmitochondrial intracellular stores which are probably specialized subcompartments of the endoplasmic reticulum, although their exact identities remain unknown. This initial response is followed by more complex Ca2+ signals: regenerative Ca2+ waves propagate across the cell, repetitive Ca2+ spikes occur, and stimulated Ca2+ entry across the plasma membrane contributes to the sustained Ca2+ signal. The mechanisms underlying these complex Ca2+ signals are unknown, although Ins(1,4,5)P3 is clearly involved. The intracellular receptor that mediates Ins(1,4,5)P3-stimulated Ca2+ mobilization has been purified and functionally reconstituted, and its amino acid sequence deduced from its cDNA sequence. These studies demonstrate that the Ins(1,4,5)P3 receptor has an integral Ca2+ channel separated from the Ins(1,4,5)P3 binding site by a long stretch of residues some of which form binding sites for allosteric regulators, and some of which are substrates for phosphorylation. In this review, we discuss the ligand recognition characteristics of Ins(1,4,5)P3 receptors, and their functional properties in their native environment and after purification, and we relate these properties to what is known of the structure of the receptor. In addition to regulation by Ins(1,4,5)P3, the Ins(1,4,5)P3 receptor is subject to many additional regulatory influences which include Ca2+, adenine nucleotides, pH and phosphorylation by protein kinases. Many of the functional and structural characteristics of the Ins(1,4,5)P3 receptor show striking similarities to another intracellular Ca2+ channel, the ryanodine receptor. These properties of the Ins(1,4,5)P3 are discussed, and their possible roles in contributing to the complex Ca2+ signals evoked by extracellular stimuli are considered.
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Affiliation(s)
- C W Taylor
- Department of Pharmacology, Cambridge, U.K
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