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Abstract
The hydrolysis of inositol lipids triggered by the occupation of cell surface receptors generates several intracellular messengers. Many different inositol phosphate isomers accumulate in stimulated cells. Of these D-myo-inositol 1,4,5-trisphosphate (Ins 1,4,5-P3) is responsible for discharging Ca2+ from intracellular stores. Specific membrane binding sites for Ins 1,4,5-P3 have been detected. The properties of these sites and their possible relationship to the calcium release process is reviewed. Ins 1,4,5-P3 binding sites may be present in discrete subcellular structures ("calciosomes"). Kinetic and some electrophysiological evidence indicates that Ins 1,4,5-P3 acts to open a Ca2+ channel. Recent progress on the purification of the receptor from neuronal tissues is summarized. Phosphorylation of Ins 1,4,5-P3 by a specific kinase results in the production of D-myo-inositol 1,3,4,5-tetraphosphate (Ins 1,3,4,5-P4). This inositol phosphate has been reported to increase the entry of Ca2+ across the plasma membrane, activate nonspecific ion channels in the plasma membrane, alter the Ca2+ content of the Ins 1,4,5-P3-releasable store, and bind to and alter the activity of certain enzymes. These data and the possible biological significance of Ins 1,3,4,5-P4 are discussed.
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Affiliation(s)
- S K Joseph
- Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia 19104
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52
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Gill DL, Ghosh TK, Mullaney JM. Calcium signalling mechanisms in endoplasmic reticulum activated by inositol 1,4,5-trisphosphate and GTP. Cell Calcium 1989; 10:363-74. [PMID: 2670240 DOI: 10.1016/0143-4160(89)90062-6] [Citation(s) in RCA: 67] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Ca2+ signals are known to mediate an array of cellular functions including secretion, contraction, and conductivity changes. In spite of the obvious role of Ca2+ in signalling, the control of Ca2+ within cells is known to be a complex phenomenon involving a number of distinct active and passive transport systems functioning within different organelles. Inositol 1,4,5-trisphosphate (IP3) is now established as a central mediator of Ca2+ mobilization, and the endoplasmic reticulum (ER) has been considered to be the site of action of IP3. However, this role has been ascribed almost by default to the ER, based on the knowledge that IP3 functions to release Ca2+ from an intracellular, nonmitochondrial, Ca2+-pumping organelle. Our interest has been to ascertain by what mechanism IP3 activates Ca2+ movements, at what intracellular locations it functions, and how the size and replenishment of the IP3-sensitive Ca2+ pool occurs. During the course of such studies, another mechanism inducing profound movements of Ca2+ within cells was identified. This process is activated by a highly sensitive and specific guanine nucleotide regulatory mechanism, which, while inducing fluxes of Ca2+ that resemble the action of IP3 under certain conditions, has now been determined to involve a quite distinct mechanism. The characteristics of this mechanism are described below. Although involving a very different Ca2+ translocation process to that activated by IP3, several important conclusions have been drawn on the relationship between IP3- and GTP-activated Ca2+ movements leading us to believe that the latter may have a regulatory role in controlling the size and/or entry of Ca2+ into the IP3-sensitive Ca2+ pool.
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Affiliation(s)
- D L Gill
- Department of Biological Chemistry, University of Maryland School of Medicine, Baltimore
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53
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Abstract
Our initial observation that GTP could, under some experimental conditions, have profound effects on Ca2+ movements across endoplasmic reticulum membranes arose from attempts to increase the sensitivity of rat liver microsomes to inositol 1,4,5 trisphosphate (IP3). Most preparations of microsomal fractions from rat liver release only a very small percentage of accumulated Ca2+ on addition of IP3. We found, rather empirically, that the addition of microM concentrations of GTP greatly enhanced the amount of Ca2+ releasable by IP3. The initial, very appealing, hypothesis was to postulate a direct effect of GTP on the IP3-sensitive Ca2+ channel. This idea is no longer tenable, as will be described below. The more likely explanation, that GTP has its effect by either fusing small microsomal vesicles together or by allowing some form of communication between adjacent membranes is considerably more complex mechanistically and also possibly has far reaching implications for the mechanisms by which cells organise and maintain their reticular structures.
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Affiliation(s)
- A P Dawson
- School of Biological Sciences, University of East Anglia, Norwich, UK
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54
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Alderson BH, Volpe P. Distribution of endoplasmic reticulum and calciosome markers in membrane fractions isolated from different regions of the canine brain. Arch Biochem Biophys 1989; 272:162-74. [PMID: 2544141 DOI: 10.1016/0003-9861(89)90207-5] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Four regions of the canine brain (frontal lobe, parieto-occipital lobe, brainstem, and cerebellum) were each fractionated by differential centrifugation into a crude mitochondrial pellet (P2) and a crude microsomal pellet (P3). Markers of endoplasmic reticulum (glucose-6-phosphate phosphatase and rotenone-insensitive NADPH cytochrome c reductase) and markers of the 1,4,5-trisphosphate (IP3)-sensitive Ca2+ store ([3H]IP3 binding and IP3-induced Ca2+ release) were measured. No correlation was found between the two classes of markers, which suggests that the IP3 receptor does not belong to the endoplasmic reticulum in canine brain. Cerebellum P2 and P3 fractions displayed levels of [3H]IP3 binding 10- to 30-fold higher, and rates of IP3-induced Ca2+ release greater than 15-fold faster than the homologous cerebrum and brainstem fractions. Actively accumulated Ca2+ was only partially released by IP3, both before and after saponin disruption of the plasma membrane compartment. The proportion of the IP3-sensitive Ca2+ store relative to that of the total (IP3-sensitive and IP3-insensitive) Ca2+ store was variable; i.e., it was larger in cerebellum P2 (approximately 90%) than in cerebrum fractions (less than 30%). Cerebellum fractions constitute the best source from which an IP3-sensitive Ca2+ storing organelle can be purified.
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Affiliation(s)
- B H Alderson
- Department of Physiology and Biophysics, University of Texas Medical Branch, Galveston 77550
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55
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Reynolds IJ, Miller RJ. Muscarinic agonists cause calcium influx and calcium mobilization in forebrain neurons in vitro. J Neurochem 1989; 53:226-33. [PMID: 2723657 DOI: 10.1111/j.1471-4159.1989.tb07318.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
We have examined the effects of the muscarinic agonist carbachol on the intracellular free Ca2+ concentration ([Ca2+]i) in primary cultures of neurons from rat forebrain using the Ca2+-sensitive fluorescent dye fura-2. Addition of carbachol increased the [Ca2+]i in approximately 60% of cells studied. Oxotremorine-M, but not pilocarpine, mimicked the effects of carbachol. The response was reduced by 60% on removal of extracellular Ca2+, a finding suggesting that muscarinic receptor activation causes Ca2+ influx in addition to intracellular Ca2+ mobilization. Tetrodotoxin and nitrendipine also significantly reduced the response to carbachol. These studies suggest that the changes in [Ca2+]i produced by activation of muscarinic receptors result in part from mobilization of intracellular Ca2+ and that influx through voltage-sensitive Ca2+ channels also provides a significant contribution to the net [Ca2+]i change observed.
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Affiliation(s)
- I J Reynolds
- Department of Pharmacological and Physiological Sciences, University of Chicago, Illinois
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56
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Abstract
The present investigation determined the binding characteristics of the radiolabeled second messenger, [3H]In(1,4,5)P3, in cerebral cortical and cerebellar membrane fragments from ethanol sensitive (LS) and resistant (SS) mice. The data demonstrated that in the two brain regions examined, LS and SS mouse lines do not differ with regard to their maximal receptor binding capacities or dissociation constants for [3H]In(1,4,5)P3. Moreover, [3H]In(1,4,5)P3 specific binding in cerebellum is inhibited in the presence of ethanol to the same extent in both mouse lines. It is concluded that the differential behavioral and cerebellar sensitivities to ethanol previously observed in these mouse lines do not reflect differences in [3H]In(1,4,5)P3 receptor binding characteristics of the brain regions examined.
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Affiliation(s)
- T L Smith
- Department of Pharmacology, University of Arizona Health Sciences Center, Tucson 85724
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57
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Iwamatsu T. Exocytosis of Cortical Alveoli and Its Initiation Time in Medaka Eggs Induced by Microinjection of Various Agents. (cortical alveolus exocytosis/inositol 1, 4, 5-trisphosphate/microinjection/medaka egg). Dev Growth Differ 1989. [DOI: 10.1111/j.1440-169x.1989.00039.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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58
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Combettes L, Berthon B, Doucet E, Erlinger S, Claret M. Characteristics of bile acid-mediated Ca2+ release from permeabilized liver cells and liver microsomes. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(17)31237-1] [Citation(s) in RCA: 33] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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59
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Baumann O, Walz B. Calcium- and inositol polyphosphate-sensitivity of the calcium-sequestering endoplasmic reticulum in the photoreceptor cells of the honeybee drone. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 1989. [DOI: 10.1007/bf00610994] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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60
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Joseph SK, Rice HL, Nicchitta CV. Characteristics of GTP-mediated microsomal Ca2+ release. BIOCHIMICA ET BIOPHYSICA ACTA 1988; 945:185-94. [PMID: 3056523 DOI: 10.1016/0005-2736(88)90481-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Guanosine triphosphate (GTP) can release Ca2+ and enhance responses to D-myo-inositol 1,4,5-trisphosphate (IP3) in crude liver microsomes in the presence of polyethylene glycol (PEG) (Dawson et al. (1986) Biochem. J. 234, 311-315). The mechanism of these responses has been further investigated. GTP gamma S which antagonizes the actions of GTP on microsomes, does not promote Ca2+ re-uptake when added after the completion of GTP-mediated Ca2+ release. However, the effects of GTP could be reversed by washing or dilution of the microsomes. Addition of PEG to the incubation medium promoted the aggregation of microsomes. Electron microscopy provided no evidence for the fusion of microsomal vesicles in the presence or absence of GTP. In the presence of PEG, GTP produced an alteration of the permeability properties of the microsomal membrane as indicated by increased leakage of an intraluminal esterase, a reduction in the mean buoyant density of the vesicles, and a decrease in the latency of mannose 6-phosphate hydrolysis. All three effects developed relatively slowly, whereas the effects of GTP on Ca2+ fluxes occurred more rapidly (complete within 15 min). A low permeability to mannose 6-phosphate was restored upon washing away the GTP. These results suggest that non-specific permeability changes may underly the effects of GTP on Ca2+ release and that, under certain conditions, GTP can reversibly modulate the permeability of a transmembrane 'pore' in microsomal membranes that can pass ions and macromolecules. The possibility that such a pore serves to link IP3-sensitive vesicles with other Ca2+-containing compartments is discussed.
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Affiliation(s)
- S K Joseph
- Department of Biochemistry and Biophysics, University of Pennsylvania School of Medicine, Philadelphia 19104
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61
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62
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Guillemette G, Balla T, Baukal AJ, Catt KJ. Characterization of inositol 1,4,5-trisphosphate receptors and calcium mobilization in a hepatic plasma membrane fraction. J Biol Chem 1988. [DOI: 10.1016/s0021-9258(18)68817-9] [Citation(s) in RCA: 124] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
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63
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MgATP-dependent glucose 6-phosphate-stimulated Ca2+ accumulation in liver microsomal fractions. Effects of inositol 1,4,5-trisphosphate and GTP. J Biol Chem 1988. [DOI: 10.1016/s0021-9258(18)69094-5] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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64
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Rengasamy A, Feinberg H. Inositol 1,4,5-trisphosphate-induced calcium release from platelet plasma membrane vesicles. Biochem Biophys Res Commun 1988; 150:1021-6. [PMID: 3257695 DOI: 10.1016/0006-291x(88)90731-0] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
A platelet membrane preparation, enriched in plasma membrane markers, took up 45Ca2+ in exchange for intravesicular Na+ and released it after the addition of inositol 1,4,5-trisphosphate (IP3). The possibility that contaminating dense tubular membrane (DTS) vesicles contributed the Ca2+ released by IP3 was eliminated by the addition of vanadate to inhibit Ca+-ATPase-mediated DTS Ca2+ sequestration and by the finding that only plasma membrane vesicles exhibit Na+-dependent Ca2+ uptake. Ca2+ released by IP3 was dependent on low extravesicular Ca2+ concentrations. IP3-induced Ca2+ release was additive to that released by Na+ addition while GTP or polyethylene glycol (PEG) had no effect. These results strongly suggest that IP3 facilitates extracellular Ca2+ influx in addition to release from DTS membranes.
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Affiliation(s)
- A Rengasamy
- Department of Pharmacology, University of Illinois, Chicago 60612
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65
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Thomas AP. Enhancement of the inositol 1,4,5-trisphosphate-releasable Ca2+ pool by GTP in permeabilized hepatocytes. J Biol Chem 1988. [DOI: 10.1016/s0021-9258(18)69125-2] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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66
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Lukács GL, Hajnóczky G, Hunyady L, Spät A. The effect of inositol 1,4,5-trisphosphate and GTP on calcium release from rat liver microsomes. BIOCHIMICA ET BIOPHYSICA ACTA 1987; 931:251-4. [PMID: 3499178 DOI: 10.1016/0167-4889(87)90213-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Inositol 1,4,5-trisphosphate (Ins(1,4,5)P3) and GTP mobilized 8% and 90% of the ionophore-releaseable Ca2+ pool from rat liver microsomes, respectively. In contrast to GTP, which acted after a lag-time, the Ins(1,4,5)P3-induced Ca2+ release was immediate. Poly(ethylene glycol) inhibited the effect of Ins(1,4,5)P3 and enhanced that of GTP. Ins(1,4,5)P3 accelerated and enhanced the GTP-induced Ca2+ release. Guanylyl imidodiphosphate inhibited competitively the GTP stimulated Ca2+ release, but not the GTP-dependent phosphorylation of the Mr 17,000 and 38,000 protein bands.
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Affiliation(s)
- G L Lukács
- Department of Physiology, Semmelweis University Medical School, Budapest, Hungary
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67
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GTP- and inositol 1,4,5-trisphosphate-activated intracellular calcium movements in neuronal and smooth muscle cell lines. J Biol Chem 1987. [DOI: 10.1016/s0021-9258(19)76504-1] [Citation(s) in RCA: 63] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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68
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Intracellular calcium uptake activated by GTP. Evidence for a possible guanine nucleotide-induced transmembrane conveyance of intracellular calcium. J Biol Chem 1987. [DOI: 10.1016/s0021-9258(19)76505-3] [Citation(s) in RCA: 73] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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69
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Worley PF, Baraban JM, Supattapone S, Wilson VS, Snyder SH. Characterization of inositol trisphosphate receptor binding in brain. Regulation by pH and calcium. J Biol Chem 1987. [DOI: 10.1016/s0021-9258(18)45326-4] [Citation(s) in RCA: 280] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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70
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Kiesel L, Lukács GL, Eberhardt I, Runnebaum B, Spät A. Effect of inositol 1,4,5-trisphosphate and GTP on calcium release from pituitary microsomes. FEBS Lett 1987; 217:85-8. [PMID: 3496242 DOI: 10.1016/0014-5793(87)81248-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Microsomal vesicles from bovine anterior pituitary accumulate Ca2+ and maintain a steady-state ambient Ca2+ level of 200 nM. IP3 and GTP both induce calcium release from the microsomal vesicles. The effect of IP3 is inhibited by polyethylene glycol (PEG), and the effect of GTP is absolutely dependent on PEG. Half-maximal effect of IP3 (without PEG) is 0.26 micron, the maximal calcium release attaining 7% of the A23187-releasable pool. The same values for GTP (in the presence of PEG) are 80 microM and 10%, respectively. GTP potentiates the effect of IP3. This potentiation is not mediated by protein phosphorylation.
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71
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Miller RJ. Bradykinin highlights the role of phospholipid metabolism in the control of nerve excitability. Trends Neurosci 1987. [DOI: 10.1016/0166-2236(87)90161-5] [Citation(s) in RCA: 61] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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