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Potential role of diacylglycerol kinases in immune-mediated diseases. Clin Sci (Lond) 2021; 134:1637-1658. [PMID: 32608491 DOI: 10.1042/cs20200389] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 06/08/2020] [Accepted: 06/22/2020] [Indexed: 02/07/2023]
Abstract
The mechanism promoting exacerbated immune responses in allergy and autoimmunity as well as those blunting the immune control of cancer cells are of primary interest in medicine. Diacylglycerol kinases (DGKs) are key modulators of signal transduction, which blunt diacylglycerol (DAG) signals and produce phosphatidic acid (PA). By modulating lipid second messengers, DGK modulate the activity of downstream signaling proteins, vesicle trafficking and membrane shape. The biological role of the DGK α and ζ isoforms in immune cells differentiation and effector function was subjected to in deep investigations. DGK α and ζ resulted in negatively regulating synergistic way basal and receptor induced DAG signals in T cells as well as leukocytes. In this way, they contributed to keep under control the immune response but also downmodulate immune response against tumors. Alteration in DGKα activity is also implicated in the pathogenesis of genetic perturbations of the immune function such as the X-linked lymphoproliferative disease 1 and localized juvenile periodontitis. These findings suggested a participation of DGK to the pathogenetic mechanisms underlying several immune-mediated diseases and prompted several researches aiming to target DGK with pharmacologic and molecular strategies. Those findings are discussed inhere together with experimental applications in tumors as well as in other immune-mediated diseases such as asthma.
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2
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DGKα in Neutrophil Biology and Its Implications for Respiratory Diseases. Int J Mol Sci 2019; 20:ijms20225673. [PMID: 31766109 PMCID: PMC6887790 DOI: 10.3390/ijms20225673] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Revised: 11/08/2019] [Accepted: 11/11/2019] [Indexed: 12/21/2022] Open
Abstract
Diacylglycerol kinases (DGKs) play a key role in phosphoinositide signaling by removing diacylglycerol and generating phosphatidic acid. Besides the well-documented role of DGKα and DGKζ as negative regulators of lymphocyte responses, a robust body of literature points to those enzymes, and specifically DGKα, as crucial regulators of leukocyte function. Upon neutrophil stimulation, DGKα activation is necessary for migration and a productive response. The role of DGKα in neutrophils is evidenced by its aberrant behavior in juvenile periodontitis patients, which express an inactive DGKα transcript. Together with in vitro experiments, this suggests that DGKs may represent potential therapeutic targets for disorders where inflammation, and neutrophils in particular, plays a major role. In this paper we focus on obstructive respiratory diseases, including asthma and chronic obstructive pulmonary disease (COPD), but also rare genetic diseases such as alpha-1-antitrypsin deficiency. Indeed, the biological role of DGKα is understudied outside the T lymphocyte field. The recent wave of research aiming to develop novel and specific inhibitors as well as KO mice will allow a better understanding of DGK's role in neutrophilic inflammation. Better knowledge and pharmacologic tools may also allow DGK to move from the laboratory bench to clinical trials.
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Abstract
Proton channels exist in a wide variety of membrane proteins where they transport protons rapidly and efficiently. Usually the proton pathway is formed mainly by water molecules present in the protein, but its function is regulated by titratable groups on critical amino acid residues in the pathway. All proton channels conduct protons by a hydrogen-bonded chain mechanism in which the proton hops from one water or titratable group to the next. Voltage-gated proton channels represent a specific subset of proton channels that have voltage- and time-dependent gating like other ion channels. However, they differ from most ion channels in their extraordinarily high selectivity, tiny conductance, strong temperature and deuterium isotope effects on conductance and gating kinetics, and insensitivity to block by steric occlusion. Gating of H(+) channels is regulated tightly by pH and voltage, ensuring that they open only when the electrochemical gradient is outward. Thus they function to extrude acid from cells. H(+) channels are expressed in many cells. During the respiratory burst in phagocytes, H(+) current compensates for electron extrusion by NADPH oxidase. Most evidence indicates that the H(+) channel is not part of the NADPH oxidase complex, but rather is a distinct and as yet unidentified molecule.
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Affiliation(s)
- Thomas E Decoursey
- Department of Molecular Biophysics and Physiology, Rush Presbyterian St. Luke's Medical Center, Chicago, Illinois 60612, USA.
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4
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Cherny VV, Henderson LM, Xu W, Thomas LL, DeCoursey TE. Activation of NADPH oxidase-related proton and electron currents in human eosinophils by arachidonic acid. J Physiol 2001; 535:783-94. [PMID: 11559775 PMCID: PMC2278825 DOI: 10.1111/j.1469-7793.2001.00783.x] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
1. Effects of arachidonic acid (AA) on proton and electron currents in human eosinophils were studied using the permeabilized-patch voltage-clamp technique, using an applied NH4+ gradient to control pH(i). 2. Superoxide anion (O2-) release was assessed by cytochrome c reduction in human eosinophils. Significant O2- release was stimulated by 5-10 microM AA. 3. AA activated diphenylene iodinium (DPI)-inhibitable inward current reflecting electron efflux through NADPH oxidase. These electron currents (I(e)) were elicited in human eosinophils at AA concentrations (3-10 microM) similar to those that induced O2- release. 4. The voltage-gated proton conductance (g(H)) in eosinophils stimulated with AA was profoundly enhanced: H+ current amplitude (I(H)) increased 4.6 times, activation was 4 times faster, and the H+ conductance-voltage (g(H)-V) relationship was shifted to substantially more negative voltages. The electrophysiological effects of AA resembled those reported for PMA, except that AA did not consistently slow tau(tail) (deactivation of H+ currents). 5. The stimulation of both proton and electron currents by AA was reversible upon washout. Repeated exposure elicited repeated responses. The activation of H+ currents by AA was dissociable from its activation of NADPH oxidase; H+ currents were enhanced at low concentrations of AA that did not elicit detectable I(e) or when NADPH oxidase was inhibited by DPI. 6. Most of the effects of AA on H+ currents qualitatively resemble those reported in whole-cell studies, reflecting a more direct action than PMA. The results are compatible with AA being an immediate activator of both NADPH oxidase and proton channels in human eosinophils.
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Affiliation(s)
- V V Cherny
- Department of Molecular Biophysics and Physiology, Rush Presbyterian St Luke's Medical Center, Chicago, IL 60612, USA.
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Montrucchio G, Alloatti G, Camussi G. Role of platelet-activating factor in cardiovascular pathophysiology. Physiol Rev 2000; 80:1669-99. [PMID: 11015622 DOI: 10.1152/physrev.2000.80.4.1669] [Citation(s) in RCA: 265] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Platelet-activating factor (PAF) is a phospholipid mediator that belongs to a family of biologically active, structurally related alkyl phosphoglycerides. PAF acts via a specific receptor that is coupled with a G protein, which activates a phosphatidylinositol-specific phospholipase C. In this review we focus on the aspects that are more relevant for the cell biology of the cardiovascular system. The in vitro studies provided evidence for a role of PAF both as intercellular and intracellular messenger involved in cell-to-cell communication. In the cardiovascular system, PAF may have a role in embryogenesis because it stimulates endothelial cell migration and angiogenesis and may affect cardiac function because it exhibits mechanical and electrophysiological actions on cardiomyocytes. Moreover, PAF may contribute to modulation of blood pressure mainly by affecting the renal vascular circulation. In pathological conditions, PAF has been involved in the hypotension and cardiac dysfunctions occurring in various cardiovascular stress situations such as cardiac anaphylaxis and hemorrhagic, traumatic, and septic shock syndromes. In addition, experimental studies indicate that PAF has a critical role in the development of myocardial ischemia-reperfusion injury. Indeed, PAF cooperates in the recruitment of leukocytes in inflamed tissue by promoting adhesion to the endothelium and extravascular transmigration of leukocytes. The finding that human heart can produce PAF, expresses PAF receptor, and is sensitive to the negative inotropic action of PAF suggests that this mediator may have a role also in human cardiovascular pathophysiology.
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Affiliation(s)
- G Montrucchio
- Laboratorio di Immunopatologia Renale, Dipartimento di Medicina Interna, Dipartimento di Biologia Animale e dell'Uomo e Istituto Nazionale di Fisica della Materia, Università di Torino, Torino, Italy
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6
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Kim DD, Ramírez MM, Durán WN. Platelet-activating factor modulates microvascular dynamics through phospholipase C in the hamster cheek pouch. Microvasc Res 2000; 59:7-13. [PMID: 10625566 DOI: 10.1006/mvre.1999.2195] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We studied the interactions between platelet-activating factor (PAF) and phospholipase C (PLC) in the modulation of microvascular responses in the hamster cheek pouch using intravital microscopy and computer-assisted image analysis. Changes in arteriolar diameter and in integrated optical intensity (IOI, an index of vascular permeability) were measured. Fluorescein-isothiocyanate-labeled dextran 150 (FITC-Dx 150) served as a tracer for macromolecular transport. 2-Nitro-4-carboxyphenyl N,N-diphenylcarbamate (NCDC) and 1-(6-((17beta-3-methoxyestra-1,3, 5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5,-dione (U-73122), two PLC inhibitors, were applied topically in separate experiments. PAF at 10(-7) M elevated IOI from baseline to a mean +/- SEM value of 70. 7 +/- 8.9 units. Pretreatment with 10(-4) and 10(-5) M NCDC and with U-73122 at 10(-5) and 10(-6) M attenuated the maximal increment in mean IOI (+/-SEM) induced by PAF at 10(-7) M to mean +/- SEM values of 30.6 +/- 6.5, 39.3 +/- 6.0, 12.1 +/- 4.8, and 41.5 +/- 6.0, respectively. The simultaneous vasoconstrictor action of 10(-7) M PAF was expressed as the experimental-to-baseline ratio, with the baseline diameter adjusted to a value of 1. PAF constricted the arterioles to a mean +/- SEM ratio of 0.30 +/- 0.07. Pretreatment with the PLC inhibitors NCDC at 10(-4) and 10(-5) M NCDC and with U-73122 at 10(-5) and 10(-6) M attenuated 10(-7) M PAF-induced vasoconstriction to mean +/- SEM diameter ratios of 0.55 +/- 0.05, 0. 48 +/- 0.06, 0.55 +/- 0.08, and 0.58 +/- 0.06, respectively. Our results demonstrate that PLC is an element of the biochemical pathway involved in PAF modulation of microvascular permeability and in PAF modulation of arteriolar diameter.
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Affiliation(s)
- D D Kim
- Program in Vascular Biology, UMDNJ-New Jersey Medical School, Newark, New Jersey, 07103-2714, USA
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7
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Izumi T, Shimizu T. Platelet-activating factor receptor: gene expression and signal transduction. BIOCHIMICA ET BIOPHYSICA ACTA 1995; 1259:317-33. [PMID: 8541341 DOI: 10.1016/0005-2760(95)00171-9] [Citation(s) in RCA: 185] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- T Izumi
- Department of Biochemistry, Faculty of Medicine, University of Tokyo, Japan
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Graham A, Russell LJ. Stimulation of low-density lipoprotein uptake in HepG2 cells by epidermal growth factor via a tyrosine kinase-dependent, but protein kinase C-independent, mechanism. Biochem J 1994; 298 Pt 3:579-84. [PMID: 8141769 PMCID: PMC1137898 DOI: 10.1042/bj2980579] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Epidermal growth factor (EGF), a potent mitogenic polypeptide, stimulated the uptake and degradation of [3H]sucrose-labelled low-density lipoprotein (LDL) by HepG2 cells. The increase in LDL uptake was prevented by the presence of the tyrosine kinase inhibitor genistein. Activation of protein kinase C with phorbol 12-myristate 13-acetate (PMA) also stimulated the uptake of [3H]LDL by HepG2 cells. When EGF and PMA were added together, PMA increased the response to EGF in an additive manner. The protein kinase C inhibitor Ro-31-8220 prevented the increase in LDL uptake caused by PMA, but did not affect EGF stimulation of LDL uptake. Similarly, down-regulation of protein kinase C activity by chronic treatment with PMA also did not affect the EGF stimulation of LDL uptake. These results suggest that the EGF stimulation of LDL uptake and degradation by HepG2 cells is mediated by a tyrosine kinase-dependent, but protein kinase C-independent, mechanism.
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Affiliation(s)
- A Graham
- Department of Biochemical Sciences, Wellcome Research Laboratories, Beckenham, Kent, U.K
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9
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Isosaki M, Minami N, Nakashima T. Calphostin C, a potent and specific inhibitor of protein kinase C, reduces phorbol ester-induced but not primary Ca(2+)-induced catecholamine secretion from digitonin-permeabilized bovine adrenal medullary cells. JAPANESE JOURNAL OF PHARMACOLOGY 1994; 64:217-9. [PMID: 7517467 DOI: 10.1254/jjp.64.217] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- M Isosaki
- Department of Pharmacology, Nara Medical University, Kashihara, Japan
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10
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Abstract
Phospholipases and protein kinases are critical for the intracellular transmission and amplification of signals induced by extracellular ligands. Chemotactic activation of phagocytes through G protein coupled receptors leads to inflammatory responses of the immune cells. Downstream of G proteins, phospholipases generate precursors for eicosanoid synthesis and are involved in the functional responses. Recently, the molecular characterization of specific enzymes of the signalling cascades has gained much attention in research.
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Affiliation(s)
- M Thelen
- Theodor Kocher Institute, University of Bern, Switzerland
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11
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DeCoursey TE, Cherny VV. Potential, pH, and arachidonate gate hydrogen ion currents in human neutrophils. Biophys J 1993; 65:1590-8. [PMID: 7506066 PMCID: PMC1225885 DOI: 10.1016/s0006-3495(93)81198-6] [Citation(s) in RCA: 145] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Indirect evidence indicates that a proton-selective conductance is activated during the respiratory burst in neutrophils. A voltage- and time-dependent H(+)-selective conductance, gH, in human neutrophils is demonstrated here directly by the whole-cell patch-clamp technique. The gH is extremely low at large negative potentials, increases slowly upon membrane depolarization, and does not inactivate. It is enhanced at high external pH or low internal pH and is inhibited by Cd2+ and Zn2+. Arachidonic acid, which plays a pivotal role in inflammatory reactions, amplifies the gH. The properties of the gH described here are compatible with its activation during the respiratory burst in stimulated neutrophils, in which it may facilitate sustained superoxide anion release by dissipating metabolically generated acid.
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Affiliation(s)
- T E DeCoursey
- Department of Physiology, Rush Presbyterian St. Luke's Medical Center, Chicago, Illinois 60612
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12
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Abstract
During the past two decades, studies describing the chemistry and biology of PAF have been extensive. This potent phosphoacylglycerol exhibits a wide variety of physiological and pathophysiological effects in various cells and tissues. PAF acts, through specific receptors and a variety of signal transduction systems, to elicit diverse biochemical responses. Several important future directions can be enumerated for the characterization of PAF receptors and their attendant signalling mechanisms. The recent cloning and sequence analysis of the gene for the PAF receptor will allow a number of important experimental approaches for characterizing the structure and analysing the function of the various domains of the receptor. Using molecular genetic and immunological technologies, questions relating to whether there is receptor heterogeneity, the precise mechanism(s) for the regulation of the PAF receptor, and the molecular details of the signalling mechanisms in which the PAF receptor is involved can be explored. Another area of major significance is the examination of the relationship between the signalling response(s) evoked by PAF binding to its receptor and signalling mechanisms activated by a myriad of other mediators, cytokines and growth factors. A very exciting recent development in which PAF receptors undoubtedly play a role is in the regulation of the function of various cellular adhesion molecules. Finally, there remain many incompletely characterized physiological and pathophysiological situations in which PAF and its receptor play a crucial signalling role. Our laboratory has been active in the elucidation of several tissue responses in which PAF exhibits major autocoid signalling responses, e.g. hepatic injury and inflammation, acute and chronic pancreatitis, and cerebral stimulation and/or trauma. As new experimental strategies are developed for characterizing the fine structure of the molecular mechanisms involved in tissue injury and inflammation, the essential role of PAF as a primary signalling molecule will be affirmed. Doubtless the next 20 years of experimental activity will be even more interesting and productive than the past two decades.
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Affiliation(s)
- W Chao
- Department of Biochemistry, University of Texas Health Science Center, San Antonio 78284-7760
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Chao W, Liu H, Hanahan DJ, Olson MS. Protein tyrosine phosphorylation and regulation of the receptor for platelet-activating factor in rat Kupffer cells. Effect of sodium vanadate. Biochem J 1992; 288 ( Pt 3):777-84. [PMID: 1335232 PMCID: PMC1131954 DOI: 10.1042/bj2880777] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Platelet-activating factor (1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine, AGEPC) and sodium vanadate (a phosphotyrosine phosphatase inhibitor) induced a time- and concentration-dependent increase in phosphotyrosine in several proteins and stimulated prostaglandin (PG) E2 production in cultured rat Kupffer cells. In addition, vanadate induced a decrease in the surface expression of AGEPC receptors and, as a consequence, inhibited AGEPC-stimulated PGE2 production. The vanadate-induced decrease in the surface expression of AGEPC receptors was time- and concentration-dependent and was partially prevented by genistein, a putative tyrosine kinase inhibitor. Upon removal of vanadate from the culture medium and re-incubation of cells in vanadate-free medium, the surface AGEPC receptors were restored within 7 h after the removal of vanadate. Both AGEPC- and vanadate-stimulated PGE2 formation was attenuated by genistein. Thus the present investigation demonstrates that both AGEPC and sodium vanadate stimulate tyrosine phosphorylation of cellular proteins, and vanadate induces a decrease in the number of the surface AGEPC receptors. These results suggest that protein tyrosine phosphorylation may play a role, directly or indirectly, in the regulation of surface expression of AGEPC receptors as well as in PGE2 production in response to vanadate and AGEPC.
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Affiliation(s)
- W Chao
- Department of Biochemistry, University of Texas Health Science Center, San Antonio 78284-7760
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14
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Xing M, Mattera R. Phosphorylation-dependent regulation of phospholipase A2 by G-proteins and Ca2+ in HL60 granulocytes. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(18)35703-x] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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15
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Kozawa O, Miwa M, Tokuda H. Inhibition by protein kinase C activation of melittin-induced arachidonic acid release in PC12 pheochromocytoma cells. Prostaglandins Leukot Essent Fatty Acids 1992; 47:215-8. [PMID: 1475278 DOI: 10.1016/0952-3278(92)90242-b] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
In rat PC12 pheochromocytoma cells, melittin, a phospholipase A2 activator, stimulated the release of arachidonic acid in a dose-dependent manner in the range between 0.1 and 1 microM. 12-O-Tetradecanoylphorbol-13-acetate (TPA), a protein kinase C-activating phorbol ester, inhibited the melittin-induced release of arachidonic acid dose-dependently in the range between 0.1 nM and 0.1 microM, whereas 4 alpha-phorbol 12, 13-didecanoate, which is inactive for protein kinase C, was ineffective in this capacity. Staurosporine, a protein kinase C inhibitor, recovered the inhibitory effect of TPA on the melittin-induced release of arachidonic acid. These results suggest that the activation of protein kinase C inhibits phospholipase A2 activity in PC12 pheochromocytoma cells.
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Affiliation(s)
- O Kozawa
- Department of Biochemistry, Institute for Developmental Research, Aichi, Japan
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16
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Fulgosi B, Colombatto S, Grillo MA. Efflux of polyamines from human lymphocytes and from L 1210 cells. THE INTERNATIONAL JOURNAL OF BIOCHEMISTRY 1992; 24:1461-4. [PMID: 1426526 DOI: 10.1016/0020-711x(92)90072-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
1. In human lymphocytes alkalinization of the cytoplasm with monensin or NH4Cl promotes release of polyamines. The effect of NH4Cl is abolished by EGTA and diltiazem. 2. Concanavalin A also promotes an increase of the efflux, counteracted again by EGTA and diltiazem. 3. By effect of TPA, polyamine efflux is decreased in the first 90 min, and later increased. The activation is partially prevented by H7 and by sphingosine. 4. In contrast with human lymphocytes, L 1210 cells release actively endogenous polyamines, but slowly radioactive polyamines. 5. Concanavalin A does not activate the latter process; A 23187 and NH4Cl on the contrary promote a much higher increase in the efflux rate than in normal lymphocytes. EGTA and diltiazem partially counteract the effect of NH4Cl on the release of radioactivity.
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Affiliation(s)
- B Fulgosi
- Dipartimento di Medicina e Oncologia Sperimentale, Università di Torino, Italy
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17
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Müller S, Nigam S. Arachidonic acid release and platelet-activating factor formation by staurosporine in human neutrophils challenged with n-formyl peptide. Eur J Pharmacol 1992; 218:251-8. [PMID: 1330596 DOI: 10.1016/0014-2999(92)90176-5] [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: 12/26/2022]
Abstract
Staurosporine, a putative protein kinase C (PKC) inhibitor, increased the release of [14C]arachidonic acid dose dependently between 100 nM and 1000 nM in human neutrophils challenged with 100 nM N-formyl-methionine-leucine-phenylalanine (FMLP). Staurosporine also increased the formation of leukotriene B4 (LTB4) and platelet-activating factor (PAF) in a dose-dependent manner. In addition, exogenously added lyso-PAF further augmented [3H]PAF formation in staurosporine-pretreated human neutrophils stimulated by FMLP, thus suggesting an activation of acetyl-CoA: lyso-PAF acetyltransferase by staurosporine. The potentiation of [14C]arachidonic acid release and [3H]PAF formation by staurosporine was further enhanced in the presence of 100 nM phorbol 12-myristate 13-acetate (PMA), which pinpoints a mechanism other than the modulation of PKC in this process, inasmuch as staurosporine antagonizes PMA-induced O2- production and [3H]PAF formation. Additional studies with other putative PKC inhibitors also revealed the potentiating effects of 1-(5-isoquinolinsulfonyl)-2-methylpiperazine (H-7, 20 microM) and sphingosine (2.5 microM) on FMLP-induced [14C]arachidonic acid release and [3H]PAF formation. We therefore conjecture that staurosporine-sensitive protein kinases including PKC are not involved in the activation of phospholipase A2 and acetyl-CoA:lyso-PAF acetyltransferase.
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Affiliation(s)
- S Müller
- Department of Gynecology, Universitätsklinikum Steglitz, Free University Berlin, Germany
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18
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Cockroft S. C-protein-regulated phospholipases C, D and A2-mediated signalling in neutrophils. ACTA ACUST UNITED AC 1992. [DOI: 10.1016/0304-4157(92)90036-a] [Citation(s) in RCA: 192] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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19
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Mustonen P, Kinnunen PK. Substrate level modulation of the activity of phospholipase A2 in vitro by 12-O-tetradecanoylphorbol-13-acetate. Biochem Biophys Res Commun 1992; 185:185-90. [PMID: 1599455 DOI: 10.1016/s0006-291x(05)80973-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The action of porcine pancreatic phospholipase A2 towards fluorescent phospholipid analogs is either enhanced or suppressed by 4 beta-12-O-tetradecanoylphorbol-13- acetate (TPA), depending on the chemical structure of the substrate and the concentration of Ca2+. In the presence of nmolar Ca2+ concentrations increasing [TPA] enhanced by approx. 5-fold the rate of hydrolysis of the pyrene-labelled acidic alkyl-acyl phospholipid, 1-octacosanyl-2-[6- (pyrene-1-yl)] hexanoyl-sn-glycero-3-phosphatidylmethanol. Maximal effect was obtained at high TPA/substrate molar ratios approaching 1:2. In the presence of 4 mM CaCl2 maximal activation was reduced to approximately 1.5-fold. With the corresponding phosphatidylcholine derivative as a substrate increasing [TPA] reduced fatty acid release maximally by 90% both at low [Ca2+] as well as in the presence of 4 mM CaCl2. Essentially identical results were obtained using 4 alpha-TPA, a stereoisomer which does not activate protein kinase C.
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Affiliation(s)
- P Mustonen
- Department of Medical Chemistry, University of Helsinki, Finland
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20
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Keloid fibroblasts are refractory to inhibition of DNA synthesis by phorbol esters. Altered response is accompanied by reduced sensitivity to prostaglandin E2 and altered down-regulation of phorbol ester binding sites. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(19)50381-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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21
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Chao W, Liu H, Hanahan D, Olson M. Platelet-activating factor-stimulated protein tyrosine phosphorylation and eicosanoid synthesis in rat Kupffer cells. Evidence for calcium-dependent and protein kinase C-dependent and -independent pathways. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(19)50486-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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22
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Tokuda H, Oiso Y, Kozawa O. Protein kinase C activation amplifies prostaglandin F2 alpha-induced prostaglandin E2 synthesis in osteoblast-like cells. J Cell Biochem 1992; 48:262-8. [PMID: 1400612 DOI: 10.1002/jcb.240480306] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
In cloned osteoblast-like cells, MC3T3-E1, prostaglandin F2 alpha (PGF2 alpha) stimulated arachidonic acid (AA) release in a dose-dependent manner in the range between 1 nM and 10 microM. 12-O-tetradecanoylphorbol-13-acetate (TPA), a protein kinase C (PKC) activator, which by itself had little effect on AA release, markedly amplified the release of AA stimulated by PGF2 alpha in a dose-dependent manner. 4 alpha-phorbol 12,13-didecanoate, a phorbol ester which is inactive for PKC, showed little effect on the PGF2 alpha-induced AA release. 1-oleoyl-2-acetylglycerol (OAG), a specific activator for PKC, mimicked TPA by enhancement of the AA release induced by PGF2 alpha. H-7, a PKC inhibitor, markedly suppressed the effect of OAG on PGF2 alpha-induced AA release. Quinacrine, a phospholipase A2 inhibitor, showed partial inhibitory effect on PGF2 alpha-induced AA release, while it suppressed the amplification by OAG of PGF2 alpha-induced AA release almost to the control level. Furthermore, TPA enhanced the AA release induced by melittin, known as a phospholipase A2 activator. On the other hand, TPA inhibited the formation of inositol trisphosphate stimulated by PGF2 alpha. Under the same condition, PGF2 alpha indeed stimulated prostaglandin E2 (PGE2) synthesis and TPA markedly amplified the PGF2 alpha-induced PGE2 synthesis as well as AA release. These results indicate that the activation of PKC amplifies PGF2 alpha-induced both AA release and PGE2 synthesis through the potentiation of phospholipase A2 activity in osteoblast-like cells.
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Affiliation(s)
- H Tokuda
- First Department of Internal Medicine, Nagoya University School of Medicine, Japan
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23
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Kawase T, Orikasa M, Suzuki A. Effect of phorbol myristate acetate on release of arachidonic acid and its metabolites in the osteoblastic MOB 3-4 cell line and its subclone, MOB 3-4-F2. Cell Signal 1992; 4:51-9. [PMID: 1571204 DOI: 10.1016/0898-6568(92)90007-u] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
We examined the effect of phorbol 12-myristate 13-acetate (PMA) on release of arachidonic acid (AA) and its metabolites in osteoblastic cells in an attempt to study mechanism of the regulation of phospholipase A2 (PLA2) activity. In the MOB 3-4-F2 cell line, a subclone of the clonal osteoblastic MOB 3-4 cell line, PMA (0.1-100 nM) changed its appearance and increased AA release in a dose- and time-dependent manner, whereas 4 alpha-phorbol 12,13-didecanoate (4 alpha-PDD) did not show a significant affect on the release. The addition of 1,2-bis(O-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA, greater than or equal to 1.5 mM), a Ca2+ chelator, almost completely inhibited the PMA-induced AA release without affecting the intrinsic AA release. Preincubation with staurosporine (5-20 nM), an inhibitor of protein kinase C (PKC), partially (approximately 60%) blocked the AA release. However, 30-min preincubation with H-7 (50-200 microM), an inhibitor of PKC, failed to block the AA release. PMA, thus, appeared to stimulate AA release partially by a staurosporine-sensitive mechanism, probably an activation of PKC, in an external Ca(2+)-dependent manner. On the other hand, MOB 3-4 cells responded to PMA with an increased AA release but not with a drastic change of its shape. Both staurosporine and BAPTA exerted similar inhibitory effects. Prolonged exposure (48 h) to PMA (0.1-10 nM) enhanced DNA synthesis of MOB 3-4-F2 cells, but not MOB 3-4 cells.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- T Kawase
- Department of Pharmacology, Niigata University School of Dentistry, Japan
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24
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Clark JD, Limbird LE. Na(+)-H+ exchanger subtypes: a predictive review. THE AMERICAN JOURNAL OF PHYSIOLOGY 1991; 261:C945-53. [PMID: 1662907 DOI: 10.1152/ajpcell.1991.261.6.c945] [Citation(s) in RCA: 111] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
In recent years, many reports have appeared describing distinct heterogeneity of proteins that heretofore were considered to be a single species or type. The division of proteins into different classes or subtypes is aided by pharmacological tools such as selective ligands, functional measurements such as those examining kinetic or regulatory differences, and molecular biological approaches that have identified distinct genes coding for similar yet distinguishable gene products. Currently, much effort is directed toward understanding the significance of these sometimes subtle differences in terms of functional consequences for the cells in which they exist. Although most reports to date involve hormone and neurotransmitter receptor subtypes, it is also possible that other cell surface molecules such as ion transporters exist as multiple subtypes. In this paper we review the current evidence that Na(+)-H+ exchange activity is mediated by different Na(+)-H+ exchanger subtypes. Although subtypes have not been identified with certainty, we can predict certain distinguishing characteristics that these putative subtypes may have that may be of value in correlating predicted gene products obtained from cDNA cloning with previously characterized Na(+)-H+ exchangers.
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Affiliation(s)
- J D Clark
- Department of Pharmacology, School of Medicine, Vanderbilt University, Nashville, Tennessee 37232
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25
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Yamazaki M, Molski TF, Stevens T, Huang CK, Becker EL, Sha'afi RI. Modulation of leukotriene B4 and platelet-activating factor binding to neutrophils. THE AMERICAN JOURNAL OF PHYSIOLOGY 1991; 261:C515-20. [PMID: 1653524 DOI: 10.1152/ajpcell.1991.261.3.c515] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Preincubation of human neutrophils with the human hormone granulocyte-macrophage colony-stimulating factor (GM-CSF) inhibits the specific binding of leukotriene B4 ([3H]LTB4) but not the nonmetabolizable bioactive platelet-activating factor ([3H]C-PAF) to intact cells. This inhibition requires that the GM-CSF interacts with intact cells. The action of GM-CSF is not prevented by pertussis toxin. Moreover, the rise in calcium produced by LTB4 but not by PAF is also inhibited in human neutrophils pretreated with GM-CSF. Interestingly, neither the inhibitory action of GM-CSF on [3H]LTB4 binding or LTB4-induced calcium rise nor the potentiation of superoxide production by GM-CSF is reduced by inhibitors of arachidonic acid metabolism by the lipoxygenase pathway. In contrast, preincubation of human neutrophils with either the chemotactic factor formyl-methionyl-leucyl-phenylalanine (fMet-Leu-Phe) or the active phorbol ester, phorbol 12-myristate 13-acetate (PMA), inhibits the binding of both [3H]LTB4 and [3H]C-PAF to intact cells. The inhibitory actions of GM-CSF, PMA, and fMet-Leu-Phe require that they interact with the intact cells; their actions cannot be reproduced in plasma membrane preparations. The effects of both GM-CSF and fMet-Leu-Phe cannot be prevented by the protein kinase C inhibitor staurosporine. The mechanisms of fMet-Leu-Phe and GM-CSF actions are probably not mediated through the release of LTB4 by the cells. Interestingly, this new action, unlike other reported effects of GM-CSF, is not mediated through a pertussis toxin-sensitive G protein (Gi alpha 2). This indicates that not all GM-CSF receptors are coupled to Gi alpha 2.
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Affiliation(s)
- M Yamazaki
- Department of Physiology, University of Connecticut Health Center, Farmington 06032
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26
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Fitzke E, Dieter P. Glucocorticoids inhibit formation of inositol phosphates in macrophages. Biochem Biophys Res Commun 1991; 178:974-9. [PMID: 1651724 DOI: 10.1016/0006-291x(91)90987-i] [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: 12/28/2022]
Abstract
Glucocorticoids inhibited the zymosan-induced formation of inositol phosphates in macrophages. No inhibition was observed with progesterone. Inhibitors of protein (cycloheximide) and RNA (actinomycin D) synthesis exhibited similar inhibitory effects. The activity of phospholipase C in subcellular fractions was not altered by hormone treatment of the cells. However, the incorporation of inositol into membrane lipids was reduced by dexamethasone. These data indicate that glucocorticoids are able to inhibit the formation of inositol phosphates; the effect of the hormone is rather due to an inhibition of the incorporation of inositol in membrane lipids than to an inhibition of phospholipase C. The anti-inflammatory action of glucocorticoids may, therefore, also be attributed to their effect on the polyphosphoinositide cycle and inositol phosphate-mediated processes.
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Affiliation(s)
- E Fitzke
- Institute of Molecular Cell Biology, University of Freiburg, Germany
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27
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Balsinde J, Diez E, Mollinedo F. Arachidonic acid release from diacylglycerol in human neutrophils. Translocation of diacylglycerol-deacylating enzyme activities from an intracellular pool to plasma membrane upon cell activation. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)98454-1] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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28
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Schatz-Munding M, Hatzelmann A, Ullrich V. The involvement of extracellular calcium in the formation of 5-lipoxygenase metabolites by human polymorphonuclear leukocytes. EUROPEAN JOURNAL OF BIOCHEMISTRY 1991; 197:487-93. [PMID: 1902789 DOI: 10.1111/j.1432-1033.1991.tb15936.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
We have addressed the question why in the presence of a Ca2+ ionophore human polymorphonuclear leukocytes generate leukotrienes in high yields, but in only low amounts after stimulation by receptor agonists like fMLF (fM, formylmethionine), leukotriene B4 or platelet-activating factor (PAF), although a significant release of intracellular calcium can be measured. Using ionomycin we can show that from the two enzymes involved, phospholipase A2 and 5-lipoxygenase, the first requires a threshold level of about 350-400 nM calcium whereas 5-lipoxygenase shows a linear dependence on calcium and saturates at this concentration. Our data indicate that the Ca2+ requirement of phospholipase A2 can only be met by an additional influx of extracellular calcium, whereas 5-lipoxygenase will operate already at levels provided by intracellular stores. Consequently, the complexing of extracellular calcium by EGTA stops phospholipase A2 activity immediately, whereas added arachidonate can be still adequately metabolized by intracellular Ca2+ release triggered by fMLF or PAF. Interestingly, PAF shows a stronger extracellular component in its Ca2+ transient than fMLF, and also generates more 5-lipoxygenase metabolites. However, a clear correlation between the amount of 5-lipoxygenase metabolites and the extracellular Ca2+ signal was lacking, since maximal activity was achieved before the bulk of the extracellular calcium was monitored. Ca2+ influx after PAF stimulation could be blocked after 2 min by EGTA, but a further increase in the formation of 5-lipoxygenase metabolites was observed. In contrast ionomycin-elicited 5-lipoxygenase activity could be stopped at any time shortly after EGTA addition.
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Affiliation(s)
- M Schatz-Munding
- Faculty of Biology, University of Konstanz, Federal Republic of Germany
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29
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Zor U, Her E, Harell T, Fischer G, Naor Z, Braquet P, Ferber E, Reiss N. Arachidonic acid release by basophilic leukemia cells and macrophages stimulated by Ca2+ ionophores, antigen and diacylglycerol: essential role for protein kinase C and prevention by glucocorticosteroids. BIOCHIMICA ET BIOPHYSICA ACTA 1991; 1091:385-92. [PMID: 2001419 DOI: 10.1016/0167-4889(91)90204-b] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The role of protein kinase C in phospholipase A2 (PLA2) activation in rat basophilic leukemia cells (RBL-2H3) and macrophages was investigated. 12-O-Tetradecanoyl phorbol 13-acetate (TPA) doubled ionomycin-induced PLA2 activity, assessed by [3H]arachidonate release. Protein kinase C inhibitors, staurosporine and K252a (100 nM) or H-7 (15 micrograms/ml) inhibited ionomycin-stimulation of PLA2 activity by 62, 75 and 80%, respectively. Down-regulation of protein kinase C by prolonged treatment with TPA inhibited Ca2(+)-ionophore A23187 or antigen-stimulation of [3H]arachidonate release by 80%. We examined whether the inhibitory effect of dexamethasone (DEX) on PLA2 activity is related to modulation of protein kinase C activity. The 50% inhibition by DEX of ionomycin elevation of [3H]arachidonate release was almost overcome by addition of TPA. The Ca2+ ionophore and antigen-induced increase in [3H]TPA binding to intact RBL cells was not impaired by DEX. However, DEX markedly reduced phosphorylation of several proteins. 1-Oleoyl-2-acetyl-glycerol (OAG) had a sustained stimulatory effect on PLA2 activity in isolated plasma membranes derived from treated bone-marrow intact mouse macrophages, while both DEX and staurosporine reduced elevated PLA2 activity by 68 and 84%, respectively. The results support an essential role for protein kinase C in regulation of PLA2 activity.
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Affiliation(s)
- U Zor
- Department of Hormone Research, Weizmann Institute of Science, Rehovot, Israel
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30
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Pace-Asciak CR, Nigam S. Hepoxilins modulate second messenger systems in the human neutrophil. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1991; 314:133-9. [PMID: 1818483 DOI: 10.1007/978-1-4684-6024-7_8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
In this chapter, we will review recent findings which implicate the hepoxilins as modulators of second messenger systems in the human neutrophil. We have shown that the hepoxilins affect calcium homeostasis in the cell and that they stimulate the release of arachidonic acid and diradylglycerol but not inositol phosphate indicating a mode of action for these 12-lipoxygenase metabolites that is independent of phospholipase C activation. In fact lipid analyses indicate that the phospholipid affected by the hepoxilins is phosphatidyl choline, and that this phospholipid is hydrolyzed by a phospholipase D. These findings indicate that the hepoxilins, which are formed by the platelet as well as the neutrophil, may affect neutrophil activation through a potential cell-cell interaction in the circulation or at pathologic sites to initiate or potentiate the inflammatory process.
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Affiliation(s)
- C R Pace-Asciak
- Research Institute, Hospital for Sick Children, Toronto, Canada
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31
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Dieter P, Schulze-Specking A, Fitzke E. Activation of phospholipase C is not correlated to the formation of prostaglandins and superoxide in cultured rat liver macrophages. Cell Signal 1991; 3:65-71. [PMID: 1645176 DOI: 10.1016/0898-6568(91)90009-j] [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: 12/28/2022]
Abstract
This study evaluates the role of inositol phosphates as possible mediators of the activation of phospholipase A2 and NADPH oxidase in cultured rat liver macrophages. Inositol phosphate formation was achieved by zymosan, immune complexes, latex particles and calcium ionophore while the release of arachidonic acid and the formation of prostaglandin E2 was also elicited by phorbol ester and NaF, but not by latex particles; generation of superoxide was obtained by zymosan and phorbol ester only. The kinetics of the formation of inositol phosphates revealed that within the first few minutes after zymosan addition inositol trisphosphate was formed, followed by inositol bisphosphate and inositol monophosphate. Pre-treatment of the cells with dexamethasone or removal of extracellular calcium led to an inhibition of the zymosan-induced formation of inositol phosphates and prostaglandin E2 but had no effect on the generation of superoxide; inhibition of the Na+/H+ exchanger by removal of extracellular sodium ions led to a decrease of the zymosan-induced synthesis of prostaglandin E2, but did not affect the formation of inositol phosphates and superoxide. Pre-treatment of the cells with phorbol ester decreased the zymosan-induced synthesis of prostaglandin E2 and superoxide, but even enhanced the zymosan-induced formation of inositol phosphates. These data indicate that in cultured rat liver macrophages the formation of prostaglandins and superoxide cannot be correlated to an activation of phospholipase C.
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Affiliation(s)
- P Dieter
- Institute of Molecular Cell Biology, Freiberg, F.R.G
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32
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Moroney MA, Forder RA, Carey F, Hoult JR. Differential regulation of 5-lipoxygenase and cyclo-oxygenase pathways of arachidonate metabolism in rat peritoneal leukocytes. Br J Pharmacol 1990; 101:128-32. [PMID: 2178012 PMCID: PMC1917650 DOI: 10.1111/j.1476-5381.1990.tb12101.x] [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] Open
Abstract
1. Simultaneous activation of the 5-lipoxygenase and cyclo-oxygenase pathways of arachidonate metabolism in rat peritoneal mixed leukocytes in response to A23187, chemoattractant N-formyl-methionine-leucine-phenylalanine (FMLP) and arachidonic acid (AA) was studied by radioimmunoassay of leukotriene B4 (LTB4) and thromboxane B2 (TXB2) respectively. 2. FMLP and AA preferentially activated cyclo-oxygenase and A23187 preferentially activated 5-lipoxygenase. Release of TXB2 preceded that of LTB4. A threshold amount of A23187 enhanced FMLP-and AA-induced LTB4 production but not that of TXB2. 3. Phorbol myristate acetate (PMA) abolished LTB4 generation in response to FMLP with much less effect on TXB2, but did not inhibit the formation of either eicosanoid caused by A23187 or AA. Instead, PMA caused a dose-dependent but modest stimulation of TXB2 generation either on its own or when added with A23187 or AA. 4. These results show that the 5-lipoxygenase and cyclo-oxygenase pathways in rat peritoneal leukocytes are regulated differently and that functional compartmentalisation of the stimulus-generation sequence operates in these cells.
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33
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Ohtsuka T, Hiura M, Yoshida K, Okamura N, Ishibashi S. A diacylglycerol kinase inhibitor, R 59 022, potentiates superoxide anion production and 46-kDa protein phosphorylation in guinea pig polymorphonuclear leukocytes. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(18)55413-2] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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34
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Takaishi K, Kawata S, Ito N, Tamura S, Shirai Y, Tarui S. Effects of phorbol ester on cell growth inhibition by transforming growth factor beta 1 in human hepatoma cell lines. Biochem Biophys Res Commun 1990; 171:91-6. [PMID: 2168181 DOI: 10.1016/0006-291x(90)91360-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The effects of phorbol ester on cell growth inhibition by transforming growth factor beta 1 (TGF-beta 1) in human hepatoma cell lines, Mahlavu and PLC/PRF/5, were investigated. TGF-beta 1 (2.5 to 10 pM) alone could not inhibit the growth of Mahlavu cells, whereas in the presence of 12-O-tetradecanoyl phorbol 13-acetate (TPA) at 1 ng/ml, TGF-beta 1 could suppress their growth in a dose-dependent manner. The growth of PLC/PRF/5 cells could be inhibited by addition of TGF-beta 1 (2.5 to 10 pM) alone in a dose-dependent manner, and this action was not affected by TPA (1 ng/ml). The TGF-beta 1 inhibition induced by TPA in Mahlavu cells could not be cancelled by addition of protein kinase C inhibitor, 1-(5-isoquinolinesulfonyl)-2-methylpiperazine (H7) (10 microM) or staurosporin (1 nM). Thus, TPA could induce TGF-beta 1 inhibition of cell growth in Mahlavu cells which did not respond to TGF-beta 1 alone, and activation of protein kinase C does not seem to be behind this TPA action.
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Affiliation(s)
- K Takaishi
- Second Department of Internal Medicine, Osaka University Medical School, Japan
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35
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Chapter 12 Phosphoinositide Metabolism during Phagocytic Cell Activation. ACTA ACUST UNITED AC 1990. [DOI: 10.1016/s0070-2161(08)60084-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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36
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Calcium is necessary but not sufficient for the platelet-activating factor release in human neutrophils stimulated by physiological stimuli. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(20)88242-8] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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37
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Yamazaki M, Gomez-Cambronero J, Durstin M, Molski TF, Becker EL, Sha'afi RI. Phorbol 12-myristate 13-acetate inhibits binding of leukotriene B4 and platelet-activating factor and the responses they induce in neutrophils: site of action. Proc Natl Acad Sci U S A 1989; 86:5791-4. [PMID: 2548188 PMCID: PMC297716 DOI: 10.1073/pnas.86.15.5791] [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: 01/01/2023] Open
Abstract
The addition of the platelet-activating factor (PAF) to neutrophils causes an increase in cytoskeletal actin, a rise in the intracellular concentration of free calcium, release of arachidonic acid, and the synthesis of PAF. The PAF synthesis in human neutrophils stimulated by PAF is greatly potentiated by the human granulocyte-macrophage colony-stimulating factor. Incubation of human neutrophils with the tumor copromoter phorbol 12-myristate 13-acetate (PMA) for 3 min prior to the addition of the stimulus inhibits all these responses produced by PAF. The inhibition is prevented when the cells are incubated with protein kinase C inhibitors such as 1-(5-isoquinolinesulfonyl)-2-methylpiperazine for 5 min prior to the addition of PMA. The rise in the intracellular concentration of free calcium in human neutrophils stimulated with leukotriene B4 is also inhibited by PMA, and this inhibition is prevented by protein kinase C inhibitors such as staurosporine. Unlike PMA, the inactive ester 4 alpha-phorbol 12,13-didecanoate has no inhibitory effect on the stimulated rise in the intracellular concentration of free calcium. The binding of either PAF or leukotriene B4 to intact cells is inhibited by PMA. The most important finding of the present studies is that PMA interferes with the binding of PAF and leukotriene B4 to their respective receptors. Whether PMA inhibits the binding of these lipid mediators by activating protein kinase C or by perturbing the membrane directly remains to be elucidated.
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Affiliation(s)
- M Yamazaki
- Department of Physiology, University of Connecticut Health Center, Farmington 06032
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38
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Krishnamurthi S, Joseph S. Arachidonate release in neutrophils: does a lack of effect of protein kinase C inhibitors imply no involvement of protein kinase C? Biochem J 1989; 261:687-8. [PMID: 2775241 PMCID: PMC1138879 DOI: 10.1042/bj2610687] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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39
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Abstract
In chemotactic factor-stimulated neutrophils, rapid increases of intracellular levels of cyclic AMP, calcium, and diacylglycerol have been observed and may be linked to protein kinase activation. The study of the physiological role and regulation of protein kinases in the neutrophil and the identification of their substrates has provided valuable information on the molecular mechanism of neutrophil activation. The focus of this review is on those aspects of protein kinases that are relevant to neutrophil activation and on the substrate proteins for these protein kinases. The possible role of protein phosphorylation in neutrophil function is also discussed.
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Affiliation(s)
- C K Huang
- Department of Pathology, University of Connecticut Health Center, Farmington 06032
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