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Launhardt L, Matzner M, Heilmann M, Heilmann I. Analysis of Phosphoinositides from Complex Plant Samples by Solid-Phase Adsorption Chromatography and Subsequent Quantification via Thin-Layer and Gas Chromatography. Methods Mol Biol 2021; 2295:379-389. [PMID: 34047988 DOI: 10.1007/978-1-0716-1362-7_21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/25/2023]
Abstract
The determination of phosphoinositide molecular species in plant material is challenging because of their low abundance concurrent with a very high abundance of other membrane lipids, such as plastidial glycolipids. Phosphoinositides harbor an inositol headgroup which carries one or more phosphate groups at different positions of the inositol, linked to diacylglycerol via a phosphodiester. Thus, a further analytical challenge is to distinguish the different inositol-phosphate headgroups as well as the fatty acids of the diacylglycerol backbone. The method presented in this chapter expands on previous protocols for phosphoinositide analysis by employing chromatographic enrichment of phospholipids and their separation from other, more abundant lipid classes, before analysis. Lipids extracted from plant material are first separated by solid-phase adsorption chromatography into fractions containing neutral lipids, glycolipids, or phospholipids. Lipids from the phospholipid fraction are then separated by thin-layer chromatography (TLC) according to their characteristic head groups, and the individual phosphatidylinositol-monophosphates and phosphatidylinositol-bisphosphates are isolated. Finally, the fatty acids associated with each isolated phosphatidylinositol-monophosphate or phosphatidylinositol-bisphosphate are analyzed in a quantitative fashion using gas chromatography (GC). The analysis of phosphoinositides by this combination of methods provides a cost-efficient and reliable alternative to lipidomics approaches requiring more extensive instrumentation.
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Affiliation(s)
- Larissa Launhardt
- Charles Tanford Protein Center, Department of Cellular Biochemistry, Institute for Biochemistry and Biotechnology, Martin-Luther-University Halle-Wittenberg, Halle (Saale), Germany
| | - Monique Matzner
- Charles Tanford Protein Center, Department of Cellular Biochemistry, Institute for Biochemistry and Biotechnology, Martin-Luther-University Halle-Wittenberg, Halle (Saale), Germany
| | - Mareike Heilmann
- Charles Tanford Protein Center, Department of Cellular Biochemistry, Institute for Biochemistry and Biotechnology, Martin-Luther-University Halle-Wittenberg, Halle (Saale), Germany
| | - Ingo Heilmann
- Charles Tanford Protein Center, Department of Cellular Biochemistry, Institute for Biochemistry and Biotechnology, Martin-Luther-University Halle-Wittenberg, Halle (Saale), Germany.
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Wilson MSC, Saiardi A. Importance of Radioactive Labelling to Elucidate Inositol Polyphosphate Signalling. Top Curr Chem (Cham) 2017; 375:14. [PMID: 28101851 PMCID: PMC5396384 DOI: 10.1007/s41061-016-0099-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Accepted: 12/21/2016] [Indexed: 01/09/2023]
Abstract
Inositol polyphosphates, in their water-soluble or lipid-bound forms, represent a large and multifaceted family of signalling molecules. Some inositol polyphosphates are well recognised as defining important signal transduction pathways, as in the case of the calcium release factor Ins(1,4,5)P3, generated by receptor activation-induced hydrolysis of the lipid PtdIns(4,5)P2 by phospholipase C. The birth of inositol polyphosphate research would not have occurred without the use of radioactive phosphate tracers that enabled the discovery of the “PI response”. Radioactive labels, mainly of phosphorus but also carbon and hydrogen (tritium), have been instrumental in the development of this research field and the establishment of the inositol polyphosphates as one of the most important networks of regulatory molecules present in eukaryotic cells. Advancements in microscopy and mass spectrometry and the development of colorimetric assays have facilitated inositol polyphosphate research, but have not eliminated the need for radioactive experimental approaches. In fact, such experiments have become easier with the cloning of the inositol polyphosphate kinases, enabling the systematic labelling of specific positions of the inositol ring with radioactive phosphate. This approach has been valuable for elucidating their metabolic pathways and identifying specific and novel functions for inositol polyphosphates. For example, the synthesis of radiolabelled inositol pyrophosphates has allowed the discovery of a new protein post-translational modification. Therefore, radioactive tracers have played and will continue to play an important role in dissecting the many complex aspects of inositol polyphosphate physiology. In this review we aim to highlight the historical importance of radioactivity in inositol polyphosphate research, as well as its modern usage.
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Affiliation(s)
- Miranda S C Wilson
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, Gower Street, London, WC1E 6BT, UK
| | - Adolfo Saiardi
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, Gower Street, London, WC1E 6BT, UK.
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3
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Heilmann M, Heilmann I. Mass measurement of polyphosphoinositides by thin-layer and gas chromatography. Methods Mol Biol 2013; 1009:25-32. [PMID: 23681520 DOI: 10.1007/978-1-62703-401-2_3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Phosphoinositides derive from the phospholipid, phosphatidylinositol (PtdIns), by phosphorylation of the inositol ring in the lipid head group. The determination of phosphoinositide species is a particular challenge, because the structurally similar inositolphosphate-head groups must be analyzed as well as the lipid-associated fatty acids. The method presented in this chapter consists of two steps: First phosphoinositides are separated by thin-layer chromatography (TLC) according to their characteristic head groups and the individual lipids are isolated. Second, the fatty acids associated with each isolated lipid are analyzed using a gas-chromatograph (GC). The combination of these two classical methods for lipid analysis, TLC and GC, provides a cost-efficient and reliable alternative to lipidomics approaches requiring more extensive instrumentation.
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Affiliation(s)
- Mareike Heilmann
- Department of Cellular Biochemistry, Institute for Biochemistry and Biotechnology, Martin-Luther-University Halle-Wittenberg, Halle, Germany
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4
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Cacas JL, Furt F, Le Guédard M, Schmitter JM, Buré C, Gerbeau-Pissot P, Moreau P, Bessoule JJ, Simon-Plas F, Mongrand S. Lipids of plant membrane rafts. Prog Lipid Res 2012; 51:272-99. [PMID: 22554527 DOI: 10.1016/j.plipres.2012.04.001] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Lipids tend to organize in mono or bilayer phases in a hydrophilic environment. While they have long been thought to be incapable of coherent lateral segregation, it is now clear that spontaneous assembly of these compounds can confer microdomain organization beyond spontaneous fluidity. Membrane raft microdomains have the ability to influence spatiotemporal organization of protein complexes, thereby allowing regulation of cellular processes. In this review, we aim at summarizing briefly: (i) the history of raft discovery in animals and plants, (ii) the main findings about structural and signalling plant lipids involved in raft segregation, (iii) imaging of plant membrane domains, and their biochemical purification through detergent-insoluble membranes, as well as the existing debate on the topic. We also discuss the potential involvement of rafts in the regulation of plant physiological processes, and further discuss the prospects of future research into plant membrane rafts.
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Affiliation(s)
- Jean-Luc Cacas
- Laboratoire de Biogenèse Membranaire, UMR 5200 CNRS, Université de Bordeaux, 146 Rue Léo Saignat, 33076 Bordeaux, France
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5
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Slabbaert JR, Khuong TM, Verstreken P. Phosphoinositides at the Neuromuscular Junction of Drosophila melanogaster: A Genetic Approach. Methods Cell Biol 2012; 108:227-47. [DOI: 10.1016/b978-0-12-386487-1.00012-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Heilmann I. Using genetic tools to understand plant phosphoinositide signalling. TRENDS IN PLANT SCIENCE 2009; 14:171-9. [PMID: 19217341 DOI: 10.1016/j.tplants.2008.12.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2008] [Revised: 11/28/2008] [Accepted: 12/09/2008] [Indexed: 05/07/2023]
Abstract
Phosphoinositides (PIs) are regulatory lipids that control various physiological processes in eukaryotic organisms. As in other eukaryotes, the plant PI system is a central regulator of metabolism. The analysis of mutant plants that lack certain PI species has revealed their physiological relevance; however, knowledge of the factors controlling the distribution of PIs and the effects on their target proteins is still limited. To understand PI functions better, genetic approaches should be combined with biochemical analyses and cell biology, as has been done in several recent publications. Here, I highlight plant-specific physiological processes that are controlled by PIs and suggest future avenues of research. A detailed understanding of the functions and effects of PIs might offer new opportunities for modulating plant growth and hardiness against environmental influences.
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Affiliation(s)
- Ingo Heilmann
- Department of Plant Biochemistry, Georg-August-University Göttingen, Justus-von-Liebig-Weg 11, 37077 Göttingen, Germany.
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7
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König S, Hoffmann M, Mosblech A, Heilmann I. Determination of content and fatty acid composition of unlabeled phosphoinositide species by thin-layer chromatography and gas chromatography. Anal Biochem 2008; 378:197-201. [PMID: 18466755 DOI: 10.1016/j.ab.2008.03.052] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2008] [Revised: 03/28/2008] [Accepted: 03/31/2008] [Indexed: 01/02/2023]
Abstract
Recent advances in research on the physiological roles of phosphoinositides in eukaryotic organisms indicate a need to distinguish molecular phosphoinositide species on the basis of their characteristic head groups as well as their glycerolipid moieties. Accurate identification of phosphoinositide species in biological samples poses an analytical challenge, because structurally similar inositol phosphate head groups must be resolved, as must lipid-associated fatty acids. Although intact phosphoinositide species have been successfully analyzed, such analyses employ state-of-the-art liquid chromatography/mass spectrometry and require expensive equipment not accessible to many researchers. Described here is a cost-efficient and reliable alternative developed by adaptation of a combination of classic methods for lipid analysis, thin-layer chromatography and gas chromatography.
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Affiliation(s)
- Sabine König
- Department of Plant Biochemistry, Albrecht-von-Haller-Institute for Plant Sciences, Georg-August-University Göttingen, 37077 Göttingen, Germany
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Beharka AA, Crowther JE, McCormack FX, Denning GM, Lees J, Tibesar E, Schlesinger LS. Pulmonary Surfactant Protein A Activates a Phosphatidylinositol 3-Kinase/Calcium Signal Transduction Pathway in Human Macrophages: Participation in the Up-Regulation of Mannose Receptor Activity. THE JOURNAL OF IMMUNOLOGY 2005; 175:2227-36. [PMID: 16081790 DOI: 10.4049/jimmunol.175.4.2227] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Surfactant protein A (SP-A), a major component of lung surfactant, binds to macrophages and has been shown to alter several macrophage biological functions, including up-regulation of macrophage mannose receptor (MR) activity. In the present study, we show that SP-A induces signal transduction pathway(s) that impact on MR expression. The addition of human, rat, or recombinant rat SP-A to human monocyte-derived macrophages significantly raised the level of cytosolic Ca2+ above baseline within 10 s of SP-A addition, as measured by spectrofluorometric analysis. SP-A induced a refractory state specific for SP-A consistent with homologous desensitization of a receptor(s) linked to calcium mobilization because a second application of SP-A did not induce a rise in cytosolic Ca2+ whereas the addition of platelet-activating factor did. Using site-directed mutations in SP-A, we determined that both the attached sugars and the collagen-like domain of SP-A are necessary to optimize Ca2+ mobilization. SP-A triggered the increase in cytosolic Ca2+ by inducing activation of phospholipase C, which leads to the hydrolysis of membrane phospholipids, yielding inositol 1,4,5-trisphosphate and mobilizing intracellularly stored Ca2+ by inositol triphosphate-sensitive channels. Finally, inhibition of PI3Ks, which appear to act upstream of phospholipase C in Ca2+ mobilization, decreased the SP-A-induced rise in MR expression, providing evidence that SP-A induction of MR activity involves the activation of a pathway in which PI3K is a component. These studies provide further evidence that SP-A produced in the lung plays a role in modulating macrophage biology, thereby contributing to the alternative activation state of the alveolar macrophage.
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MESH Headings
- Adult
- Animals
- Binding Sites/immunology
- Calcium/metabolism
- Calcium Signaling/genetics
- Calcium Signaling/immunology
- Collagen/physiology
- Cytosol/metabolism
- Dose-Response Relationship, Immunologic
- Humans
- Inositol 1,4,5-Trisphosphate/metabolism
- Inositol 1,4,5-Trisphosphate/physiology
- Intracellular Fluid/metabolism
- Lectins, C-Type/biosynthesis
- Lectins, C-Type/metabolism
- Lipopolysaccharides/pharmacology
- Macrophage Activation/genetics
- Macrophage Activation/immunology
- Macrophages/enzymology
- Macrophages/metabolism
- Mannose Receptor
- Mannose-Binding Lectins/biosynthesis
- Mannose-Binding Lectins/metabolism
- Monocytes/enzymology
- Monocytes/immunology
- Monocytes/metabolism
- Oligosaccharides/physiology
- Phosphatidylinositol 3-Kinases/metabolism
- Phosphatidylinositol 3-Kinases/physiology
- Protein Structure, Tertiary/physiology
- Pulmonary Surfactant-Associated Protein A/genetics
- Pulmonary Surfactant-Associated Protein A/pharmacology
- Pulmonary Surfactant-Associated Protein A/physiology
- Rats
- Receptors, Cell Surface/biosynthesis
- Receptors, Cell Surface/metabolism
- U937 Cells
- Up-Regulation/genetics
- Up-Regulation/immunology
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Affiliation(s)
- Alison A Beharka
- Interdisciplinary Program in Immunology and Department of Internal Medicine, University of Iowa, Iowa City, IA 52240, USA
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9
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Nilssen LS, Dajani O, Christoffersen T, Sandnes D. Sustained diacylglycerol accumulation resulting from prolonged G protein-coupled receptor agonist-induced phosphoinositide breakdown in hepatocytes. J Cell Biochem 2005; 94:389-402. [PMID: 15526278 DOI: 10.1002/jcb.20260] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Studies in various cells have led to the idea that agonist-stimulated diacylglycerol (DAG) generation results from an early, transient phospholipase C (PLC)-catalyzed phosphoinositide breakdown, while a more sustained elevation of DAG originates from phosphatidylcholine (PC). We have examined this issue further, using cultured rat hepatocytes, and report here that various G protein-coupled receptor (GPCR) agonists, including vasopressin (VP), angiotensin II (Ang.II), prostaglandin F2alpha, and norepinephrine (NE), may give rise to a prolonged phosphoinositide hydrolysis. Preincubation of hepatocytes with 1-butanol to prevent conversion of phosphatidic acid (PA) did not affect the agonist-induced DAG accumulation, suggesting that phospholipase D-mediated breakdown of PC was not involved. In contrast, the GPCR agonists induced phosphoinositide turnover, assessed by accumulation of inositol phosphates, that was sustained for up to 18 h, even under conditions where PLC was partially desensitized. Pretreatment of hepatocytes with wortmannin, to inhibit synthesis of phosphatidylinositol 4-phosphate and phosphatidylinositol 4,5-bisphosphate (PIP2), prevented agonist-induced inositol phosphate and DAG accumulation. Upon VP stimulation the level of PIP) declined, but only transiently, while increases in inositol 1,4,5-trisphosphate (InsP3) and DAG mass were sustained, suggesting that efficient resynthesis of PIP2 allowed sustained PLC activity. This was confirmed when cells were pretreated with wortmannin to prevent resynthesis of PIP2. Furthermore, metabolism of InsP3 was rapid, compared to that of DAG, with a more than 20-fold difference in half-life. Thus, rapid metabolism of InsP3 and efficient resynthesis of PIP2 may account for the larger amount of DAG generated and the more sustained time course, compared to InsP3. The results suggest that DAG accumulation that is sustained for many hours in response to VP, Ang.II, NE, and prostaglandin F2alpha in hepatocytes is mainly due to phosphoinositide breakdown.
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Affiliation(s)
- Laila Sortvik Nilssen
- Department of Pharmacology, Medical Faculty, University of Oslo, PO Box 1057 Blindern, N-0316 Oslo, Norway.
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10
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Miller A, Stanton C, Devery R. Modulation of arachidonic acid distribution by conjugated linoleic acid isomers and linoleic acid in MCF-7 and SW480 cancer cells. Lipids 2001; 36:1161-8. [PMID: 11768161 DOI: 10.1007/s11745-001-0827-0] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The relationship between growth and alterations in arachidonic acid (AA) metabolism in human breast (MCF-7) and colon (SW480) cancer cells was studied. Four different fatty acid preparations were evaluated: a mixture of conjugated linoleic acid (CLA) isomers (c9,t11, t10,c12, c11,t13, and minor amounts of other isomers), the pure c9,t11-CLA isomer, the pure t10,c12-CLA isomer, and linoleic acid (LA) (all at a lipid concentration of 16 microg/mL). 14C-AA uptake into the monoglyceride fraction of MCF-7 cells was significantly increased following 24 h incubation with the CLA mixture (P < 0.05) and c9,t11-CLA (P < 0.02). In contrast to the MCF-7 cells, 14C-AA uptake into the triglyceride fraction of the SW480 cells was increased while uptake into the phospholipids was reduced following treatment with the CLA mixture (P < 0.02) and c9,t11-CLA (P < 0.05). Distribution of 14C-AA among phospholipid classes was altered by CLA treatments in both cell lines. The c9,t11-CLA isomer decreased (P < 0.05) uptake of 14C-AA into phosphatidylcholine while increasing (P < 0.05) uptake into phosphatidylethanolamine in both cell lines. Both the CLA mixture and the t10,c12-CLA isomer increased (P < 0.01) uptake of 14C-AA into phosphatidylserine in the SW480 cells but had no effect on this phospholipid in the MCF-7 cells. Release of 14C-AA derivatives was not altered by CLA treatments but was increased (P < 0.05) by LA in the SW480 cell line. The CLA mixture of isomers and c9,t11-CLA isomer inhibited 14C-AA conversion to 14C-prostaglandin E2 (PGE2) by 20-30% (P < 0.05) while increasing 14C-PGF2alpha by 17-44% relative to controls in both cell lines. LA significantly (P < 0.05) increased 14C-PGD2 by 13-19% in both cell lines and increased 14C-PGE2 by 20% in the SW480 cell line only. LA significantly (P < 0.05) increased 5-hydroperoxyeicosatetraenoate by 27% in the MCF-7 cell line. Lipid peroxidation, as determined by increased levels of 8-epi-prostaglandin F2alpha (8-epi-PGF2alpha), was observed following treatment with c9,t11-CLA isomer in both cell lines (P < 0.02) and with t10,c12-CLA isomer in the MCF-7 cell line only (P < 0.05). These data indicate that the growth-promoting effects of LA in the SW480 cell line may be associated with enhanced conversion of AA to PGE2 but that the growth-suppressing effects of CLA isomers in both cell lines may be due to changes in AA distribution among cellular lipids and an altered prostaglandin profile.
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Affiliation(s)
- A Miller
- School of Biotechnology, Dublin City University, Dublin, Ireland
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11
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Lund PE, Shariatmadari R, Uustare A, Detheux M, Parmentier M, Kukkonen JP, Akerman KE. The orexin OX1 receptor activates a novel Ca2+ influx pathway necessary for coupling to phospholipase C. J Biol Chem 2000; 275:30806-12. [PMID: 10880509 DOI: 10.1074/jbc.m002603200] [Citation(s) in RCA: 131] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Ca(2+) elevations in Chinese hamster ovary cells stably expressing OX(1) receptors were measured using fluorescent Ca(2+) indicators fura-2 and fluo-3. Stimulation with orexin-A led to pronounced Ca(2+) elevations with an EC(50) around 1 nm. When the extracellular [Ca(2+)] was reduced to a submicromolar concentration, the EC(50) was increased 100-fold. Similarly, the inositol 1,4,5-trisphosphate production in the presence of 1 mm external Ca(2+) was about 2 orders of magnitude more sensitive to orexin-A stimulation than in low extracellular Ca(2+). The shift in the potency was not caused by depletion of intracellular Ca(2+) but by a requirement of extracellular Ca(2+) for production of inositol 1,4,5-trisphosphate. Fura-2 experiments with the "Mn(2+)-quench technique" indicated a direct activation of a cation influx pathway by OX(1) receptor independent of Ca(2+) release or pool depletion. Furthermore, depolarization of the cells to +60 mV, which almost nullifies the driving force for Ca(2+) entry, abolished the Ca(2+) response to low concentrations of orexin-A. The results thus suggest that OX(1) receptor activation leads to two responses, (i) a Ca(2+) influx and (ii) a direct stimulation of phospholipase C, and that these two responses converge at the level of phospholipase C where the former markedly enhances the potency of the latter.
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Affiliation(s)
- P E Lund
- Department of Physiology, Division of Cell Physiology, Uppsala University, Biomedical Centre (BMC), P.O. Box 572, S-75123 Uppsala, Sweden
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12
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Kobrinsky E, Spielman AI, Rosenzweig S, Marks AR. Ceramide triggers intracellular calcium release via the IP(3) receptor in Xenopus laevis oocytes. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 277:C665-72. [PMID: 10516096 DOI: 10.1152/ajpcell.1999.277.4.c665] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Ceramide, a product of sphingomyelin turnover, is a lipid second messenger that mediates diverse signaling pathways, including those leading to cell cycle arrest and differentiation. The mechanism(s) by which ceramide signals downstream events have not been fully elucidated. Here we show that, in Xenopus laevis oocytes, ceramide-induced maturation is associated with the release of intracellular calcium stores. Ceramide caused a dose-dependent elevation in the second messenger inositol 1,4,5-trisphosphate (IP(3)) via activation of G(q/11)alpha and phospholipase C-betaX. Elevation of IP(3), in turn, activated the IP(3) receptor calcium release channel on the endoplasmic reticulum, resulting in a rise in cytoplasmic calcium. Thus our study demonstrates that cross talk between the ceramide and phosphoinositide signaling pathways modulates intracellular calcium homeostasis.
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Affiliation(s)
- E Kobrinsky
- Molecular Cardiology Program, Division of Cardiology, Department of Medicine, Columbia University College of Physicians and Surgeons, New York 10032, USA
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13
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Holmberg CI, Kukkonen JP, Bischoff A, Näsman J, Courtney MJ, Michel MC, Akerman KE. Alpha2B-adrenoceptors couple to Ca2+ increase in both endogenous and recombinant expression systems. Eur J Pharmacol 1998; 363:65-74. [PMID: 9877083 DOI: 10.1016/s0014-2999(98)00780-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The ability of cloned human alpha2B-adrenoceptors heterologously expressed in Sf9 cells and endogenous alpha2B-adrenoceptors in NG 108-15 neuroblastoma x glioma cells to couple to increase of intracellular Ca2+ was studied. Ca2+ increases in NG 108-15 cells were detectable but slight, whereas those in alpha2B-adrenoceptor-expressing Sf9 cells were greater. In the latter, the maximum Ca2+ increase correlated positively, and the EC50-value of noradrenaline negatively, with the receptor expression density. The order of potency of the agonists was D-medetomidine ([D]-4-[5]-[1-(2,3-dimethylphenyl)ethyl]-1H-imidazole) > noradrenaline approximately = clonidine > oxymetazoline, with clonidine and UK14,304 (5-bromo-N-[4,5-dihydro-1H-imidazole-2-yl]-6-quinoxalinamine) being weak partial agonists. In Sf9 cells Ca2+ increases consisted of concomitant mobilization from an intracellular store and influx of extracellular Ca2+. In these cells alpha2B-adrenoceptor stimulation also increased the inositol 1,4,5-trisphosphate mass. We conclude that alpha2B-adrenoceptors can couple to intracellular Ca2+ increases which may involve prior activation of phospholipase C.
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MESH Headings
- Animals
- Calcium/metabolism
- Calcium Signaling
- Cell Division
- Cells, Cultured
- Cloning, Molecular
- Dose-Response Relationship, Drug
- Humans
- In Vitro Techniques
- Ligands
- Norepinephrine/pharmacology
- Receptors, Adrenergic, alpha-2/classification
- Receptors, Adrenergic, alpha-2/genetics
- Receptors, Adrenergic, alpha-2/metabolism
- Recombinant Proteins/pharmacology
- Spodoptera/genetics
- Tumor Cells, Cultured
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Affiliation(s)
- C I Holmberg
- Turku Centre for Biotechnology, University of Turku, and Department of Biochemistry and Pharmacy, Abo Akademi University, Finland
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14
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Denning GM, Railsback MA, Rasmussen GT, Cox CD, Britigan BE. Pseudomonas pyocyanine alters calcium signaling in human airway epithelial cells. THE AMERICAN JOURNAL OF PHYSIOLOGY 1998; 274:L893-900. [PMID: 9609727 DOI: 10.1152/ajplung.1998.274.6.l893] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Pseudomonas aeruginosa, an opportunistic human pathogen, causes both acute and chronic lung disease. P. aeruginosa exerts many of its pathophysiological effects by secreting virulence factors, including pyocyanine, a redox-active compound that increases intracellular oxidant stress. Because oxidant stress has been shown to affect cytosolic Ca2+ concentration ([Ca2+]c) in other cell types, we studied the effect of pyocyanine on [Ca2+]c in human airway epithelial cells (A549 and HBE). At lower concentrations, pyocyanine inhibits inositol 1,4,5-trisphosphate formation and [Ca2+]c increases in response to G protein-coupled receptor agonists. Conversely, at higher concentrations, pyocyanine itself increases [Ca2+]c. The pyocyanine-dependent [Ca2+]c increase appears to be oxidant dependent and to result from increased inositol trisphosphate and release of Ca2+ from intracellular stores. Ca2+ plays a central role in epithelial cell function, including regulation of ion transport, mucus secretion, and ciliary beat frequency. By disrupting Ca2+ homeostasis, pyocyanine could interfere with these critical functions and contribute to the pathophysiological effects observed in Pseudomonas-associated lung disease.
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Affiliation(s)
- G M Denning
- Department of Internal Medicine, Veterans Affairs Medical Center and The University of Iowa, Iowa City, Iowa, 52242, USA
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15
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Allen V, Swigart P, Cheung R, Cockcroft S, Katan M. Regulation of inositol lipid-specific phospholipase cdelta by changes in Ca2+ ion concentrations. Biochem J 1997; 327 ( Pt 2):545-52. [PMID: 9359428 PMCID: PMC1218828 DOI: 10.1042/bj3270545] [Citation(s) in RCA: 150] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Studies of inositol lipid-specific phospholipase C (PLC) have elucidated the main regulatory pathways for PLCbeta and PLCgamma but the regulation of PLCdelta isoenzymes still remains obscure. Here we demonstrate that an increase in Ca2+ ion concentration within the physiological range (0.1-10 microM) is sufficient to stimulate PLCdelta1, but not PLCgamma1 and PLCbeta1, to hydrolyse cellular inositol lipids present in permeabilized cells. The activity of PLCdelta1 is further enhanced in the presence of phosphatidylinositol transfer protein (PI-TP). Both full activation by Ca2+ ions and stimulation in the presence of PI-TP require an intact PH domain involved in the membrane attachment of PLCdelta1. The physiological implication of this study is that PLCdelta1 could correspond to a previously uncharacterized PLC responsible for Ca2+ ion-stimulated inositol lipid hydrolysis observed in many cellular systems.
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Affiliation(s)
- V Allen
- CRC Centre for Cell and Molecular Biology, Chester Beatty Laboratories, Fulham Road, London SW3 6JB, U.K
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16
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Knotz S, Mercier A. Cyclic 3′5′ adenosine monophosphate mediates dopamine-enhanced hindgut contractions in the crayfish, Procambarus clarkii. ACTA ACUST UNITED AC 1995. [DOI: 10.1016/0300-9629(95)98520-q] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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17
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Christ M, Douwes K, Eisen C, Bechtner G, Theisen K, Wehling M. Rapid effects of aldosterone on sodium transport in vascular smooth muscle cells. Hypertension 1995; 25:117-23. [PMID: 7843742 DOI: 10.1161/01.hyp.25.1.117] [Citation(s) in RCA: 77] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Increasing evidence has accumulated for rapid nongenomic steroid actions in various cell systems and, more recently, for rapid aldosterone effects on the Na(+)-H+ antiport in human mononuclear leukocytes. The aim of the present study was to demonstrate a rapid, nongenomic aldosterone action in rat vascular smooth muscle cells as a key effector cell in cardiovascular regulation. Basal 22Na+ influx in quiescent vascular smooth muscle cells was 22.1 +/- 1.9 nmol/mg protein per minute (mean +/- SEM, n = 9). Aldosterone (1 nmol/L) stimulated influx to 28.6 +/- 1.5 nmol/mg protein per minute after 4 minutes (n = 9, P < .05), with a half-maximal effect between 0.1 and 0.5 nmol/L; the effects were inhibited by ethylisopropylamiloride, the specific inhibitor of the Na(+)-H+ exchanger, demonstrating the involvement of this transport system in rapid effects of aldosterone. Hydrocortisone (1 mumol/L) was ineffective, and fludrocortisone and deoxycorticosterone increased influx with half-maximal effects at approximately 0.5 nmol/L. Canrenone, a classic antagonist of aldosterone action, did not inhibit stimulation by aldosterone at a 1000-fold excess concentration. Aldosterone significantly stimulated intracellular inositol 1,4,5-trisphosphate levels (P < .05) after 30 seconds; the inhibitors of phospholipase C, neomycin and U-73122, inhibited aldosterone-stimulated Na+ influx and increase of intracellular inositol 1,4,5-trisphosphate. The rapid stimulation of sodium transport in vascular smooth muscle cells and the pharmacological characteristics of this effect are clearly incompatible with the classic, genomic pathway of steroid action and represent further evidence for nongenomic effects of aldosterone.
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Affiliation(s)
- M Christ
- Medizinische Klinik, Klinikum Innenstadt, University of Munich, FRG
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18
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Banno Y, Okano Y, Nozawa Y. Thrombin-mediated phosphoinositide hydrolysis in Chinese hamster ovary cells overexpressing phospholipase C-delta 1. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(17)40758-7] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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19
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Stoll L, Denning G, Kasner N, Hunninghake G. Platelet-activating factor may stimulate both receptor-dependent and receptor-independent increases in [Ca2+] in human airway epithelial cells. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(17)41771-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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20
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Stephens L, Jackson TR, Hawkins PT. Activation of phosphatidylinositol 4,5-bisphosphate supply by agonists and non-hydrolysable GTP analogues. Biochem J 1993; 296 ( Pt 2):481-8. [PMID: 8257441 PMCID: PMC1137720 DOI: 10.1042/bj2960481] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
PtdIns(4,5)P2 serves as a precursor of a diverse family of signalling molecules, including diacylglycerol (and hence phosphatidic acid), Ins(1,4,5)P3 [and hence Ins(1,3,4,5)P4] and PtdIns(3,4,5)P3. The production of these messengers can be activated by agonists, and therefore the rate of utilization of PtdIns(4,5)P2 can vary dramatically. Although cells can only meet these large changes in demand for PtdIns(4,5)P2 by increasing its synthesis and/or by continuously cycling it at a rate that exceeds its potential consumption (avoiding the need for a co-ordinated activation mechanism), no satisfactory explanation for how this is achieved in agonist-stimulated cells has yet been provided. We show here that, in streptolysin-O-permeabilized neutrophils, N-formylmethionyl-leucyl-phenylalanine (FMLP), platelet-activating factor (PAF) and non-hydrolysable GTP analogues can cause large activations of PtdIns4P 5-kinase, suggesting that cells can accommodate agonist-activated rates of consumption of PtdIns(4,5)P2 without having to sustain continuous, comparably rapid and energetically expensive 'futile cycling' reactions.
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Affiliation(s)
- L Stephens
- Department of Development and Signalling, AFRC Babraham Institute, Cambridge, U.K
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21
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Stephens LR, Jackson TR, Hawkins PT. Agonist-stimulated synthesis of phosphatidylinositol(3,4,5)-trisphosphate: a new intracellular signalling system? BIOCHIMICA ET BIOPHYSICA ACTA 1993; 1179:27-75. [PMID: 8399352 DOI: 10.1016/0167-4889(93)90072-w] [Citation(s) in RCA: 383] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- L R Stephens
- Department of Development and Signalling, AFRC Babraham Institute, Cambridge, UK
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22
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Tran D, Gascard P, Berthon B, Fukami K, Takenawa T, Giraud F, Claret M. Cellular distribution of polyphosphoinositides in rat hepatocytes. Cell Signal 1993; 5:565-81. [PMID: 8312134 DOI: 10.1016/0898-6568(93)90052-n] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The distribution of total phospholipids, phosphatidylinositol 4-phosphate (PIP) and phosphatidylinositol 4,5-bisphosphate (PIP2) was studied in isolated rat hepatocytes: (i) by mass assay and isotopic labelling in the fractions of plasma membranes, microsomes, mitochondria and nuclei prepared from isolated hepatocytes and (ii) by immunolocalization of PIP2 with a specific antibody (kt3g) in whole hepatocytes and isolated nuclei. Mass measurement and isotopic labelling showed that PIP was distributed in all four fractions. PIP2 was present in the plasma membrane and the nuclei. In whole cells, PIP2 was also detected in the plasma membrane by immunolocalization with the anti-PIP2 antibody kt3g. In unpolarized single hepatocytes, PIP2 distributed evenly throughout the plasma membrane. However, in polarized cell couplets, PIP2 was the most often undetectable in the lateral domain between the cells, and distributed preferentially in the sinusoidal domain of the plasma membrane. These results suggest that hepatocytes segregate PIP2 in particular domains of their plasma membrane. In purified fractions of nuclei, immunolocalization experiments showed that PIP2 was present uniquely in the nuclear envelope.
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Affiliation(s)
- D Tran
- Unité de Recherche INSERM U. 274, Université Paris-Sud, Orsay, France
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23
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Thomsen C, Mulvihill ER, Haldeman B, Pickering DS, Hampson DR, Suzdak PD. A pharmacological characterization of the mGluR1 alpha subtype of the metabotropic glutamate receptor expressed in a cloned baby hamster kidney cell line. Brain Res 1993; 619:22-8. [PMID: 7690672 DOI: 10.1016/0006-8993(93)91592-g] [Citation(s) in RCA: 81] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The pharmacological specificity of the mGluR1 alpha subtype of the metabotropic glutamate receptor (mGluR) was examined in a cloned baby hamster kidney cell line (BHK-ts13) measuring [3H]glutamate binding and inositol phosphate (PI) hydrolysis. PI-hydrolysis was maximally stimulated by quisqualate (1112 +/- 105% of basal), glutamate (1061 +/- 70% of basal), ibotenate (1097 +/- 115% of basal) and beta-N-methylamino-L-alanine (BMAA) (1010 +/- 104% of basal). In contrast, the maximal stimulation of PI-hydrolysis by (1S,3R)-1-amino-cyclopentane-1,3-dicarboxylic acid (t-ACPD) was only 673 +/- 78% of the basal level. The relative order of potency was quisqualate > glutamate > ibotenate > t-ACPD > BMAA. Agonist-stimulated PI-hydrolysis was attenuated (25 +/- 4% inhibition) by L-2-amino-3-phosphonopropionic acid and partially blocked (44 +/- 7%) by pertussis toxin treatment. Saturation binding studies with [3H]glutamate on membranes prepared from BHK-ts13 cells expressing the mGluR1 alpha subtype showed that glutamate binds to a single affinity state of this receptor with a limited capacity (Kd = 296 nM, Bmax = 0.8 pmol/mg protein). In competition experiments, [3H]glutamate was displaced by quisqualate, glutamate, ibotenate, t-ACPD and BMAA with a rank order of potency similar to that found for stimulation of PI-hydrolysis.
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Affiliation(s)
- C Thomsen
- Novo Nordisk A/S, CNS Discovery, Pharmaceuticals Research, Måløv, Denmark
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24
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Pickering DS, Thomsen C, Suzdak PD, Fletcher EJ, Robitaille R, Salter MW, MacDonald JF, Huang XP, Hampson DR. A comparison of two alternatively spliced forms of a metabotropic glutamate receptor coupled to phosphoinositide turnover. J Neurochem 1993; 61:85-92. [PMID: 8390570 DOI: 10.1111/j.1471-4159.1993.tb03540.x] [Citation(s) in RCA: 85] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
A comparison of the pharmacological and physiological properties of the metabotropic glutamate 1 alpha and 1 beta receptors (mGluR1 alpha and mGluR1 beta) expressed in baby hamster kidney (BHK 570) cells was performed. The mGluR1 beta receptor is an alternatively spliced form of mGluR1 alpha with a modified carboxy terminus. Immunoblots of membranes from the two cell lines probed with receptor-specific antipeptide antibodies showed that mGluR1 alpha migrated with an M(r) = 154,000, whereas mGluR1 beta migrated with an M(r) = 96,000. Immunofluorescence imaging of receptors expressed in BHK 570 cells revealed that the mGluR1 alpha receptor was localized to patches along the plasmalemma and on intracellular membranes surrounding the nucleus, whereas mGluR1 beta was distributed diffusely throughout the cell. Agonist activation of the mGluR1 alpha and the mGluR1 beta receptors stimulated phosphoinositide hydrolysis. At both receptors, glutamate, quisqualate, and ibotenate were full agonists, whereas trans-(+)-1-aminocyclopentane-1,3-dicarboxylate appeared to act as a partial agonist. The stimulation of phosphoinositide hydrolysis by mGluR1 alpha showed pertussis toxin-sensitive and insensitive components, whereas the mGluR1 beta response displayed only the toxin-insensitive component. The mGluR1 alpha and mGluR1 beta receptors also increased intracellular calcium levels by inducing release from intracellular stores. These results indicate that the different carboxy terminal sequences of the two receptors directly influences G protein coupling and subcellular deposition of the receptor polypeptides and suggest that the two receptors may subserve different roles in the nervous system.
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Affiliation(s)
- D S Pickering
- Faculty of Pharmacy, University of Toronto, Ontario, Canada
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25
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Bolt MJ, Bissonnette BM, Wali RK, Hartmann SC, Brasitus TA, Sitrin MD. Characterization of phosphoinositide-specific phospholipase C in rat colonocyte membranes. Biochem J 1993; 292 ( Pt 1):271-6. [PMID: 8389128 PMCID: PMC1134300 DOI: 10.1042/bj2920271] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The phosphoinositide signal transduction pathway mediates important processes in intestinal physiology, yet the key enzyme, phosphoinositide-specific phospholipase C (PI-PLC), is not well-characterized in the colon. PI-PLC activity was examined in rat colonic membranes using exogenous [3H]phosphatidylinositol 4,5-bisphosphate (PIP2) as substrate, and beta-glycerophosphate to suppress degradation of substrate or product. The activity of membrane PI-PLC increased 6-fold with the addition of alamethicin, and a further 2-3-fold enhancement was observed with 10 microM guanosine 5'-[gamma-thio]triphosphate (GTP[S]), suggesting the involvement of G-protein(s). The effect of GTP[S] appeared to be specific, as up to 100 microM adenosine 5'-[gamma-thio]-triphosphate failed to stimulate PI-PLC activity, and guanosine 5'-[beta-thio]diphosphate inhibited activity. The response of membrane PI-PLC to Ca2+ was biphasic, while > 0.5 mM Mg2+ was inhibitory with or without GTP[S]. Comparable total PI-PLC activities and responses to GTP[S] and Ca2+ were observed in purified brush-border and basolateral membranes. Western immunoblots probed with monoclonal antibodies to PLC isoenzymes PLC-beta 1, -gamma 1 and -delta 1 demonstrated that these antipodal plasma membranes contain predominantly the PLC-delta 1 isoform, with small amounts of PLC-gamma 1 present but no detectable PLC-beta 1. PLC-gamma 1 was the major isoform detected in cytosol.
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Affiliation(s)
- M J Bolt
- Department of Medicine, University of Chicago, IL 60637
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26
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Jackson T, Stephens L, Hawkins P. Receptor specificity of growth factor-stimulated synthesis of 3-phosphorylated inositol lipids in Swiss 3T3 cells. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(18)42049-2] [Citation(s) in RCA: 82] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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27
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Anderson L, Cummings J, Smyth JF. Rapid and selective isolation of radiolabelled inositol phosphates from cancer cells using solid-phase extraction. JOURNAL OF CHROMATOGRAPHY 1992; 574:150-5. [PMID: 1629280 DOI: 10.1016/0378-4347(92)80111-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
A method is described for rapid and selective determination of radiolabelled inositol phosphates in cancer cells using solid-phase extraction with Bond Elut strong anion-exchange minicolumns. The inositol phosphates IP1, IP2 and IP3 are selectively eluted with 0.05, 0.3 and 0.8 M ammonium formate-0.1 M formic acid, respectively. Cancer cells are extracted with 10% perchloric acid which is then neutralised prior to loading samples on to the minicolumns. Recovery is 54.1, 66.6 and 61.3% for IP1, IP2 and IP3 with between-day coefficients of variation of 7.6, 6.8 and 1.9%, respectively. When the method was applied to cancer cells high-performance liquid chromatographic analyses confirmed both the identity of the IP1, IP2 and IP3 fractions and showed that there was no detectable cross contamination of these inositol phosphates with each other.
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Affiliation(s)
- L Anderson
- Imperial Cancer Research Fund, Medical Oncology Unit, Western General Hospital, Edinburgh, UK
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28
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Ruggiero M, Wang LM, Pierce JH. Mitogenic signal transduction in normal and transformed 32D hematopoietic cells. FEBS Lett 1991; 291:203-7. [PMID: 1936266 DOI: 10.1016/0014-5793(91)81284-f] [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: 12/29/2022]
Abstract
We studied mitogenic signal transduction in normal and oncogene-transformed 32D cells, a murine hematopoietic cell line that is normally dependent on interleukin-3 (IL3) for proliferation and survival. The formation of second messengers was measured in normal cells stimulated with IL3, and in cells transfected with foreign growth factor receptor genes and stimulated with appropriate growth factors. We also measured the steady-state level of second messengers in 32D cells transformed by erbB, abl, and src oncogenes which abrogate growth factor requirement. We found that IL3 stimulated the formation of diacylglycerol independently of inositol lipid turnover, but concomitantly with increased turnover of phosphatidylcholine. Epidermal growth factor (EGF), and platelet-derived growth factor (PDGF) stimulated the 'classical' turnover of inositol lipids with formation of diacylglycerol and calcium-mobilizing inositol phosphates. Colony stimulating factor-1 triggered inositol lipid turnover, although to a much lower extent than EGF and PDGF. Transformed cells showed elevated levels of diacylglycerol together with increased turnover of phosphoinositides and phosphatidylcholine. Taken together these results indicate that different growth factors and oncoproteins associate with multiple signalling pathways in 32D cells.
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Affiliation(s)
- M Ruggiero
- Laboratory of Cellular and Molecular Biology, National Cancer Institute, Bethesda, MD 20892
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29
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Denning G, Welsh M. Polarized distribution of bradykinin receptors on airway epithelial cells and independent coupling to second messenger pathways. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)98784-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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30
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Howl J, Ismail T, Strain AJ, Kirk CJ, Anderson D, Wheatley M. Characterization of the human liver vasopressin receptor. Profound differences between human and rat vasopressin-receptor-mediated responses suggest only a minor role for vasopressin in regulating human hepatic function. Biochem J 1991; 276 ( Pt 1):189-95. [PMID: 2039469 PMCID: PMC1151163 DOI: 10.1042/bj2760189] [Citation(s) in RCA: 55] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The [Arg8]vasopressin (AVP) receptor expressed by human hepatocytes was characterized, and compared with the rat hepatic V1a vasopressin receptor subtype. In addition to determining the pharmacological profile of the human receptor, the cellular responses to AVP were measured in human and rat hepatocytes by assaying glycogen phosphorylase alpha activity and DNA synthesis. Marked differences were observed between human and rat hepatocytes regarding vasopressin receptors and the intracellular consequences of stimulation by AVP. Data presented in this paper demonstrate the following, (i) Vasopressin V1a receptors are present in low abundance on human hepatocytes. (ii) Species differences exist between human and rat V1a receptors with respect to the affinity of some selective antagonists. (iii) AVP-stimulated glycogen phosphorylase a activation in human hepatocytes was approx. 5% of that observed in rat cells. (iv) In contrast with rat hepatocytes, DNA synthesis in human cells in culture was not stimulated by AVP. It is concluded that vasopressin plays only a minor role in the regulation of human hepatic function. Furthermore, conclusions drawn from observations made with AVP and its analogues on rat hepatic function cannot be directly extrapolated to the human situation.
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Affiliation(s)
- J Howl
- School of Biochemistry, University of Birmingham, U.K
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31
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Rubiera C, Lazo PS, Shears SB. Polarized subcellular distribution of the 1-, 4- and 5-phosphatase activities that metabolize inositol 1,4,5-trisphosphate in intestinal epithelial cells. Biochem J 1990; 269:353-8. [PMID: 2167065 PMCID: PMC1131584 DOI: 10.1042/bj2690353] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
In intestinal epithelial cells, Ins(1,4,5)P3 is metabolized both by an intracellular 5-phosphatase and by less specific extracellular phosphatases [Rubiera, Velasco, Michell, Lazo & Shears (1988) Biochem. J. 255, 131-137]. A total of 91% of intracellular Ins(1,4,5)P3 5-phosphatase was particulate, and was preferentially associated with plasma membranes rather than with other subcellular organelles. A soluble Ins(1,4,5)P3 3-kinase activity was also characterized, further supporting the idea that inositol phosphates are important in enterocyte function. We have studied the distribution of Ins(1,4,5)P3 phosphatase activities in basolateral and brush-border domains of the plasma membrane. Compared with homogenates, the extracellular phosphatases were 13-17-fold enriched in brush-border membranes, but only 2-fold enriched in basolateral membranes. The 1- and 4-phosphates of Ins(1,4,5)P3 were hydrolysed at equal rates by the extracellular phosphatases; these enzymes are proposed to have digestive functions. The intracellular particulate 5-phosphatase was 2-fold enriched in brush-border membranes and 13-fold enriched in basolateral membranes, at the same pole of the cell where Ins(1,4,5)P3 is believed to be generated. This is opposite to the polarized distribution of particulate 5-phosphatase in hepatocytes [Shears, Evans, Kirk & Michell (1988) Biochem. J. 256, 363-369]; these differences in subcellular distribution may be important in determining cell-specific metabolism of Ins(1,4,5)P3.
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Affiliation(s)
- C Rubiera
- Departamento de Biologia Funcional, Universidad de Oviedo, Spain
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32
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Taylor GS, Garcia JG, Dukes R, English D. High-performance liquid chromatographic analysis of radiolabeled inositol phosphates. Anal Biochem 1990; 188:118-22. [PMID: 2221351 DOI: 10.1016/0003-2697(90)90538-k] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Separation of inositol phosphates by low-pressure anion-exchange chromatography yields unsatisfactory results, while previously described anion-exchange HPLC methods require such extensive processing times that they preclude efficient sample analysis. Using a low-capacity Vydac nucleotide anion-exchange column, we have developed a method which allows complete separation of myo-inositol, inositol 1-phosphate, inositol 1,4-bisphosphate, inositol 1,4,5-trisphosphate, and inositol 1,3,4,5-tetrakisphosphate in approximately 10 min followed by a 5-min column regeneration time. This method provided exceptional reproducibility and quantitative recovery of each inositol phosphate. One column was used for over 300 separations with no loss in performance or alteration in elution pattern. A modified procedure with a 14-min gradient was developed to separate the 1,3,4- and 1,4,5-isomers of inositol trisphosphate. These separation procedures were used to characterize the kinetics of degradation of inositol phosphates by lysates of erythrocytes and neutrophils. We conclude that these procedures are applicable for rapid and quantitative analysis of radiolabeled inositol phosphates in cellular extracts.
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Affiliation(s)
- G S Taylor
- Department of Medicine, Indiana University School of Medicine, Indianapolis 46202
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33
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Vannucchi S, Pasquali F, Fiorelli G, Bianchini P, Ruggiero M. Effect of heparin on proliferation and signalling in BC3H-1 muscle cells. Evidence for specific binding sites. FEBS Lett 1990; 263:137-41. [PMID: 2158901 DOI: 10.1016/0014-5793(90)80723-v] [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: 12/30/2022]
Abstract
We studied binding and growth inhibitory properties of different glycosaminoglycans in growing and differentiated BC3H-1 muscle cells. Heparin (10 micrograms/ml) and heparan sulfate (10 micrograms/ml) significantly inhibited DNA synthesis in growing and differentiated cells, as monitored by [3H]thymidine incorporation. Binding of heparin to BC3H-1 cells was specific and time-dependent. Heparan sulfate was the only glycosaminoglycan able to displace [3H]heparin (IC50, 3.2 x 10(-7) M), although it was 10-fold less effective than heparin itself (IC50, 3.6 x 10(-8) M). Scatchard analysis revealed the existence of high-affinity heparin binding sites (Kd, 5 x 10(-8) M). Furthermore, heparin inhibited serum-induced stimulation of inositol lipid turnover. Taken together, these results indicate that heparin inhibits BC3H-1 cell growth by interacting with the cell surface, possibly disrupting the flow of growth factor-related mitogenic signalling.
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Affiliation(s)
- S Vannucchi
- Istiuto di Patologia Generale, University of Firenze, Italy
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34
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Abstract
This review summarises the methods available for the mass measurement of inositol phosphates, i.e., use of radioactive inositol lipid precursors, optical techniques, gas chromatography, mass spectrometry, nuclear magnetic resonance, fast atom bombardment and assays specific for Ins(1,4,5)P3. Examples of the use of each method, its sensitivity, advantages and drawbacks are given.
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Affiliation(s)
- S Palmer
- Department of Biochemistry, University of Glasgow, U.K
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35
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Schulz I. Signaling Transduction in Hormone‐ and Neurotransmitter‐Induced Enzyme Secretion from the Exocrine Pancreas. Compr Physiol 1989. [DOI: 10.1002/cphy.cp060322] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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36
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Kass GE, Duddy SK, Moore GA, Orrenius S. 2,5-Di-(tert-butyl)-1,4-benzohydroquinone rapidly elevates cytosolic Ca2+ concentration by mobilizing the inositol 1,4,5-trisphosphate-sensitive Ca2+ pool. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(19)84809-3] [Citation(s) in RCA: 189] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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37
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Chaudhry A, Conway BR, Laychock SG, Rubin RP. Analysis of the regulation of phosphatidylinositol-4,5-bisphosphate synthesis by arachidonic acid in exocrine pancreas. Arch Biochem Biophys 1989; 272:488-95. [PMID: 2546502 DOI: 10.1016/0003-9861(89)90244-0] [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: 01/01/2023]
Abstract
In pancreatic acinar cells prelabeled with either 32Pi or myo-[3H]inositol, arachidonic acid (10-50 microM) rapidly decreased the steady-state levels of [32P]phosphatidylinositol 4',5'-bisphosphate [( 32P]PtdIns4,5P2) and inhibited carbachol-stimulated accumulation of [3H]inositol trisphosphate [( 3H]InsP3). Both actions of arachidonic acid were rapidly reversed by bovine serum albumin (BSA). Indomethacin and nordihydoguaiaretic acid failed to block the inhibitory effects of arachidonic acid on [32P]PtdIns4,5P2 levels. Arachidonic acid (10-50 microM) also caused a prompt depletion of cellular ATP which was rapidly reversed by BSA. The ATP-depleting action of arachidonate paralleled in terms of concentration dependence and time course its inhibitory effects on [32P]PtdIns4,5P2 and [3H]InsP3 levels. Exposure of acinar cells to 50 microM arachidonic acid produced an increase in oxygen consumption which exceeded that elicited by either carbachol or ionomycin. Arachidonic acid (10-50 microM) also caused a concentration-dependent rise in cytosolic Ca2+, which was partially obtunded by Ca2+ deprivation. A proposed mechanism involving arachidonic acid as a negative feedback regulator of polyphosphoinositide turnover in exocrine pancreas is discussed.
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Affiliation(s)
- A Chaudhry
- Department of Pharmacology, Medical College of Virginia, Richmond 23298
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38
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Spitzer JA, Rodriguez de Turco EB. Inositol lipid metabolism in vasopressin stimulated hepatocytes from rats infused with tumor necrosis factor. Biochem Biophys Res Commun 1989; 161:197-203. [PMID: 2543408 DOI: 10.1016/0006-291x(89)91580-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
We studied the effect of i.v. infusion of human recombinant tumor necrosis factor alpha (rHuTNF alpha, Cetus, 15 micrograms/100 g bw over 3 h) on vasopressin (VP)-stimulated 32P-inositol lipid turnover and the release of 3H-inositol phosphates in isolated rat hepatocytes. The early VP-induced decrease (within 30 s) in 32P-phosphatidylinositol 4-phosphate and 32P-phosphatidylinositol 4,5-bisphosphate labeling was significantly reduced (-40%) and at the same time the uptake of 32P into phosphatidic acid was 50% lower than in saline-infused (matched control) rats. Within 5 min of VP-stimulation, lower 32P phosphatidylinositol (-40%) and higher 32P-phosphatidic acid (+30%) labeling were observed in rHuTNF alpha-infused rats. Infusion of rHuTNF alpha also affected the VP-induced release of 3H-inositol phosphates. The accumulation of 3H-inositol-labeled water soluble products was decreased by 25% and 17% at 30 s and 10 min, respectively. These data show that rHuTNF alpha mimics early perturbations induced by Escherichia coli endotoxin infusion in VP-stimulated inositol lipid metabolism in rat hepatocytes.
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Affiliation(s)
- J A Spitzer
- Department of Physiology, Louisiana State University Medical Center, New Orleans 70112
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39
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Sharma RJ, Woods NM, Cobbold PH, Grant DA. Receptor-mediated endocytosis of asialoglycoproteins and diferric transferrin is independent of second messengers. Biochem J 1989; 259:81-9. [PMID: 2541688 PMCID: PMC1138475 DOI: 10.1042/bj2590081] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The intracellular concentrations of cyclic AMP, polyphosphoinosides and free Ca2+ were unaffected during receptor-mediated endocytosis of the neoglycoprotein beta-D-galactosyl-bovine serum albumin (D-Gal-BSA) by isolated hepatocytes. Elevation of either intracellular cyclic AMP by glucagon or inositol phosphates and Ca2+ by vasopressin were without effect on the binding and internalization of D-Gal-BSA. The normal response of this cell to glucagon- and vasopressin-mediated mobilization of these second messengers was not modified in the presence of saturating concentrations of D-Gal-BSA. Receptor-mediated endocytosis of diferric transferrin (Fe3+-TRF) by both hepatocytes and HL60 cells was also shown to be independent of second messengers, although the unequivocal expression of the transferrin receptor by hepatocytes could not be satisfactorily demonstrated. The results of the present study are at variance with a suggested regulatory role for second messengers in receptor-mediated endocytosis of serum-derived ligands such as asialoglycoproteins and Fe3+-TRF. Receptor phosphorylation by protein kinase C in particular has been proposed to regulate the distribution and recycling of these receptors in actively endocytosing cells. We would suggest that if receptor phosphorylation has a regulatory role during endocytosis, it is likely to be mediated by a second-messenger-independent protein kinase analogous to casein kinase II. An alternative interpretation is that phosphorylation has no physiological significance and receptor-mediated endocytosis is a constitutive event coupled to membrane turnover.
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Affiliation(s)
- R J Sharma
- Department of Surgery, St. George's Hospital Medical School, London, U.K
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40
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Augert G, Blackmore PF, Exton JH. Changes in the concentration and fatty acid composition of phosphoinositides induced by hormones in hepatocytes. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(19)81651-4] [Citation(s) in RCA: 34] [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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41
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Nielsen JR, Hansen HS, Jensen B. Arginine vasopressin stimulates phosphoinositide turnover in an enriched rat Leydig cell preparation. Mol Cell Endocrinol 1989; 61:181-8. [PMID: 2537241 DOI: 10.1016/0303-7207(89)90129-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
An enriched rat Leydig cell preparation was preincubated with [14C]arachidonic acid. Stimulation of the cells with arginine vasopressin (AVP) (1 microM) for 2 min caused a significant increase in labelled phosphatidic acid and a significant fall in radioactivity in phosphatidylinositol and phosphatidylinositol 4-monophosphate + phosphatidylinositol 4,5-bisphosphate. Preincubation with dibutyryl cyclic AMP had no effect on the AVP-induced phospholipid turnover. Leydig cells were preincubated with myo-[2-3]inositol for 22 h and then with 10 mM LiCl for 10 min. Exposure to AVP (1 microM) induced a rise in labelled inositol phosphates. The response was inhibited when the cells were preincubated with the phorbol ester, 4 beta-phorbol 12-myristate 13-acetate (0.16 microM) for 10 min. These results provide evidence for an AVP-induced phospholipase C stimulation in rat Leydig cells and suggest a protein kinase C-dependent feedback inhibition of the stimulation. Other agonists that might have a regulatory function in the testis were tested for possible effects on phosphoinositide metabolism. Of prostaglandin E2 (10 microns,) angiotensin II (0.1 microM), and bradykinin (0.9 microM), only the latter induced a significant increase in the labelled inositol phosphates. This suggests that Leydig cells possess a bradykinin receptor which can activate phospholipase C.
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Affiliation(s)
- J R Nielsen
- PharmaBiotec Research Center, Royal Danish School of Pharmacy, Copenhagen, Denmark
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42
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Palmer S, Hughes KT, Lee DY, Wakelam MJ. Development of a novel, Ins(1,4,5)P3-specific binding assay. Its use to determine the intracellular concentration of Ins(1,4,5)P3 in unstimulated and vasopressin-stimulated rat hepatocytes. Cell Signal 1989; 1:147-56. [PMID: 2642027 DOI: 10.1016/0898-6568(89)90004-1] [Citation(s) in RCA: 159] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The binding of [3H]Ins(1,4,5)P3 to bovine adrenocortical microsomes has been shown to be rapid, reversible and saturable. The microsomal preparation contained a single population of high affinity sites (KD = 6.82+/-2.3 nM, Bmax = 370+/-38 fmol/mg protein). The binding site was shown to exhibit positional specificity with respect to inositol trisphosphate binding, i.e. Ins(2,4,5)P3 was able to compete with [3H]Ins(1,4,5)P3 whereas Ins(1,3,4)P3 was not. Ins(1,3,4,5)P4 showed a similar affinity for the receptor as Ins(2,4,5)P3 whereas the other inositol phosphates tested, ATP, GTP and 2,3-DPG, were poor competitors. [3H]Ins(1,4,5)P3-binding was independent of free Ca2+ concentrations. The adrenocortical microsomal preparation has been incorporated into an assay which has been used to determine the basal and vasopressin-stimulated content of neutralised acid extracts of rat hepatocytes. Intracellular concentrations of Ins(1,4,5)P3 were calculated to be 0.22+/-0.15 microM basal and 2.53+/-1.8 microM at peak stimulation. This assay provides a simple, specific and quantitative method for the measurement of Ins(1,4,5)P3 concentrations in the picomolar range.
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Affiliation(s)
- S Palmer
- Institute of Biochemistry, University of Glasgow, U.K
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43
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Morris AJ, Storey DJ, Downes CP, Michell RH. Dephosphorylation of 1D-myo-inositol 1,4-bisphosphate in rat liver. Biochem J 1988; 254:655-60. [PMID: 2848493 PMCID: PMC1135135 DOI: 10.1042/bj2540655] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Dephosphorylation of 1D-myo-inositol 1,4-bisphosphate [Ins(1,4)P2] in rat liver is catalysed by a cytosolic phosphatase that removes the 1-phosphate group. The Km for Ins(1,4)P2 is approx. 17 microM. Li+ (100 mM) causes 50% inhibition of Ins(1,4)P2 phosphatase activity when activity is measured at the very low substrate concentration of 10 nM, but on raising the substrate concentration to 100 microM there is a greater than 10-fold increase in sensitivity to Li+, suggesting that Li+ acts mainly, but not entirely, as an uncompetitive inhibitor of Ins(1,4)P2 phosphatase. In addition, rat liver cytosol shows Li+-sensitive phosphatase activity against 1D-myo-inositol 1-,3- and 4-monophosphates. The Ins(1,4)P2 1-phosphatase and inositol monophosphatase activities all share an apparent Mr of 47 x 10(3), as determined by gel-filtration chromatography. However, the Ins(1,4)P2 1-phosphatase is more sensitive to inactivation by heat, and can be separated from inositol monophosphatase activity by anion-exchange chromatography. We conclude that rat liver cytosol contains an Ins(1,4)P2 1-phosphatase that is distinct from, but in many ways similar to, inositol monophosphatase.
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Affiliation(s)
- A J Morris
- Department of Biochemistry, University of Birmingham, U.K
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44
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Salmon DM, Bolton TB. Early events in inositol phosphate metabolism in longitudinal smooth muscle from guinea-pig intestine stimulated with carbachol. Biochem J 1988; 254:553-7. [PMID: 3178772 PMCID: PMC1135113 DOI: 10.1042/bj2540553] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
In longitudinal smooth muscle from guinea-pig intestine prelabelled with [3H]inositol, carbachol produced a 3-fold increase in [3H]inositol 1,4,5-trisphosphate within 2 s, and there was also a simultaneous increase in [3H]inositol 1,4-bisphosphate. 3H-labelling of inositol 1,3,4,5-tetrakisphosphate was not significantly increased until 60 s after carbachol stimulation, and the accumulation of [3H]inositol 1,3,4-trisphosphate was relatively small.
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Affiliation(s)
- D M Salmon
- Department of Pharmacology, St. George's Hospital Medical School, London, U.K
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45
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Rodriguez de Turco EB, Spitzer JA. Early effects of Escherichia coli endotoxin infusion on vasopressin-stimulated breakdown and metabolism of inositol lipids in rat hepatocytes. Biochem Biophys Res Commun 1988; 155:151-9. [PMID: 3046609 DOI: 10.1016/s0006-291x(88)81062-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The turnover of vasopressin-stimulated 32P-phosphoinositides and 32P-phosphatidic acid and accumulation of [2-3H]-inositol phosphates were examined in hepatocytes from rats infused i.v. with saline and E. coli endotoxin for 3 hrs. Within 60s of VP stimulation the decrease in phosphatidylinositol 4-phosphate and phosphatidylinositol 4,5-bisphosphate labeling as well as the increased uptake of 32P into phosphatidic acid were similar in both groups. However, at a later time (300s) the 32P-phosphatidylinositol turnover was greatly decreased concomitantly with a higher labeling of phosphatidic acid. The accumulation of [2-3H]-inositol phosphates in ET-cells was significantly decreased both at 30s and 600s after VP addition. The distribution of [2-3H]-inositol labeling accumulated in the different inositol phosphate fractions over the first 30s of VP stimulation showed a tendency to lower accumulation of inositol trisphosphate, and a significantly lower accumulation of inositol bisphosphate simultaneously with a higher labeling of the inositol tetrakisphosphate fraction. These observations reflect an early effect of ET-infusion on VP-stimulated inositol lipid turnover and on the subsequent metabolism of the released inositol phosphates.
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46
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Michell RH, Kirk CJ, Maccallum SH, Hunt PA. Inositol lipids: receptor-stimulated hydrolysis and cellular lipid pools. Philos Trans R Soc Lond B Biol Sci 1988; 320:239-46. [PMID: 2906136 DOI: 10.1098/rstb.1988.0074] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Our current knowledge of the process by which receptors stimulate the hydrolysis of phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P2) has its origin in the discovery by Hokin & Hokin (J. biol. Chem. 263, 967 (1953] that some pancreatic secretagogues not only elicit exocrine secretion but also stimulate the metabolism of membrane phospholipids. Despite the recent elucidation of many aspects of this widespread signalling system, there is still little information on the control of the supply of its substrate, PtdIns(4,5)P2. In particular, some studies have suggested that inositol-lipid-mediated signalling involves much or all of the inositol lipid complement of the stimulated cells, whereas other observations have equally clearly implicated the receptor-activated hydrolysis of an inositol phospholipid pool that comprises only a small fraction of the total cellular complement of these lipids. These studies, which have largely employed radiochemical analyses using single isotopes, are briefly reviewed. In addition, we report the first information obtained by a new procedure for analysing the metabolic characteristics of the inositol lipids that are broken down during stimulation. This technique employs cells that are doubly labelled in the inositol moiety of their lipids (to isotopic equilibrium with 14C and only briefly with 3H) to search for functional metabolic heterogeneity among the inositol lipids of stimulated cells. Using this method, we have found that the inositol phosphates liberated in stimulated cells during brief stimulation of V1a-vasopressin receptors or prostaglandin F2 alpha receptors come from phospholipid that has a turnover rate typical of the bulk of the cellular inositol lipids.
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Affiliation(s)
- R H Michell
- Department of Biochemistry, University of Birmingham, U.K
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47
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Rodriguez de Turco EB, Spitzer JA. Kinetics of diacylglycerol accumulation in response to vasopressin stimulation in hepatocytes of continuously endotoxaemic rats. Biochem J 1988; 253:73-9. [PMID: 3138986 PMCID: PMC1149259 DOI: 10.1042/bj2530073] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The content and composition of 1,2-diacyl-sn-glycerol (1,2-DAG) was determined in hepatocytes from saline (0.9% NaCl)- and Escherichia coli endotoxin (ET)-infused rats upon continuous vasopressin (VP) (10(-8) M) stimulation. In both experimental groups the accumulation of 1,2-DAG was detected after a lag period (2-5 min), was sustained up to the last time analysed (10 min), and C18:0- and C20:4-fatty-acid-containing-DAG accumulation preceded that of DAG containing other acyl groups. In hepatocytes from ET-infused rats the VP-induced accumulation of DAG was delayed and was decreased by 50%, showing a C18:0/C20:4 molar ratio of 1.6 as compared with 1.1 for cells from saline-infused rats. A similar lower cellular response to VP stimulation was observed in cells prelabelled with [14C]C20:4 fatty acid. The accumulation of [14C]C20:4-DAG (lower in ET than in saline-infused rats) was paralleled by a decrease in phosphatidylinositol (PI) labelling, whereas phosphatidic acid showed a transient increase by 5 min in saline- but not in ET-infused rats. The present results demonstrate that the previously reported impairment in the early degradation of poly-PI and later in the 'PI cycle' during VP stimulation [Rodriguez de Turco & Spitzer (1987) Metab. Clin. Exp. 36, 753-760] is also reflected at the level of their phosphodiesteratic product, DAG. Moreover, the kinetics of the accumulation of DAG acyl groups is consistent with the idea that the initial release of C18:0- and C20:4-DAG (possibly derived from inositol lipids) could regulate the subsequent enlargement of this pool by stimulating a phospholipase C-mediated degradation of other phospholipids (e.g. phosphatidylcholine).
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48
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Drøbak BK, Ferguson IB, Dawson AP, Irvine RF. Inositol-containing lipids in suspension-cultured plant cells: an isotopic study. PLANT PHYSIOLOGY 1988; 87:217-22. [PMID: 16666106 PMCID: PMC1054728 DOI: 10.1104/pp.87.1.217] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Polar lipids were extracted from suspension-cultured tomato (Lycopersicon esculentum Mill.) cells and analyzed by thin layer chromatography. Four major inositol-containing compounds were found, and incorporation of [(32)P]orthosphosphate, [2-(3)H]glycerol, and myo-[2-(3)H]inositol was studied. Results showed that phosphatidylinositol-monophosphate is the phospholipid in these cells displaying the most rapid incorporation of [(32)P]orthophosphate. We suggest that the tracer is incorporated primarily into the phosphomonoester group. Two inositol-containing lipids showed chromatographic behavior similar to phosphatidylinositol-4,5-bisphosphate when using standard thin layer chromatography techniques. The labeling pattern of these compounds, however, reveals that it is unlikely that either of these is identical to phosphatidylinositol-4,5-bisphosphate. Should phosphatidylinositol-bisphosphate be present in suspension cultured plant cells, our data indicate chemical abundancies substantially lower than previously reported.
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Affiliation(s)
- B K Drøbak
- Department of Soil, Water and Plant Nutrition, Royal Veterinary- and Agricultural University, Thorvaldsensvej 40, 1871 Copenhagen C., Denmark
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Pierce JH, Ruggiero M, Fleming TP, Di Fiore PP, Greenberger JS, Varticovski L, Schlessinger J, Rovera G, Aaronson SA. Signal transduction through the EGF receptor transfected in IL-3-dependent hematopoietic cells. Science 1988; 239:628-31. [PMID: 3257584 DOI: 10.1126/science.3257584] [Citation(s) in RCA: 198] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
An expression vector for the epidermal growth factor (EGF) receptor was introduced into the 32D myeloid cell line, which is devoid of EGF receptors and absolutely dependent on interleukin-3 (IL-3) for its proliferation and survival. Expression of the EGF receptor conferred the ability to utilize EGF for transduction of a mitogenic signal. When the transfected cells were propagated in EGF, they exhibited a more mature myeloid phenotype than was observed under conditions of IL-3-directed growth. Moreover, exposure to EGF led to a rapid stimulation of phosphoinositide metabolism, while IL-3 had no detectable effect on phosphoinositide turnover either in control or EGF receptor-transfected 32D cells. Although the transfected cells exhibited high levels of functional EGF receptors, they remained nontumorigenic. In contrast, transfection of v-erbB, an amino-terminal truncated form of the EGF receptor with constitutive tyrosine kinase activity, not only abrogated the IL-3 growth factor requirement of 32D cells, but caused them to become tumorigenic in nude mice. These results show that a naïve hematopoietic cell expresses all of the intracellular components of the EGF-signaling pathway necessary to evoke a mitogenic response and sustain continuous proliferation.
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Affiliation(s)
- J H Pierce
- Laboratory of Cellular and Molecular Biology, National Cancer Institute, Bethesda, MD 20892
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50
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Combettes L, Dumont M, Berthon B, Erlinger S, Claret M. Release of calcium from the endoplasmic reticulum by bile acids in rat liver cells. J Biol Chem 1988. [DOI: 10.1016/s0021-9258(18)69205-1] [Citation(s) in RCA: 60] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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