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The immune modulating activity of the Helicobacter pylori HP-NAP: Friend or foe? Toxicon 2010; 56:1186-92. [DOI: 10.1016/j.toxicon.2009.09.020] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2009] [Accepted: 09/30/2009] [Indexed: 12/20/2022]
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Tithof PK, Watts S, Ganey PE. Protein tyrosine kinase involvement in the production of superoxide anion by neutrophils exposed to Aroclor 1242, a mixture of polychlorinated biphenyls. Biochem Pharmacol 1997; 53:1833-42. [PMID: 9256158 DOI: 10.1016/s0006-2952(97)82447-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Neutrophils produce superoxide anion (O2-) when exposed in vitro to Aroclor 1242, a mixture of polychlorinated biphenyls (PCBs). The mechanism for this effect shares some similarities with the mechanism by which the physiologic agonist f-Met-Leu-Phe (fMLP) activates neutrophils. Since production of O2- in response to fMLP involves GTP-binding proteins and protein tyrosine kinases (PTKs), the current study was undertaken to determine whether these signalling pathways are involved in PCB-induced neutrophil activation. Neutrophils exposed to Aroclor 1242 or fMLP produced significant O2-. Pretreatment of intact neutrophils with pertussis toxin or cholera toxin or exposure of permeabilized cells to GDPbetaS significantly inhibited O2- production in fMLP-treated neutrophils but did not alter the response to Aroclor 1242. Pretreatment with genistein, an inhibitor of PTKs, significantly inhibited O2- production in both Aroclor 1242- and fMLP-treated neutrophils; however, daidzein, a structural analogue of genistein which lacks activity against PTKs, was without effect. Exposure of neutrophils to Aroclor 1242 resulted in an increase within 1 min in tyrosine phosphorylation of proteins in the 40 and 60 kDa molecular mass ranges which persisted for up to 10 min. Similar results were obtained with 2,2',4,4'-tetrachlorobiphenyl (2,2',4,4'-TCB), a PCB congener that stimulates O2- production. In contrast, 3,3',4,4',5-pentachlorobiphenyl (3,3',4,4',5-PeCB), a congener that does not generate O2-, caused only a transient increase in tyrosine phosphorylation of proteins in the 40 kDa range with no effect on 60 kDa proteins. These data suggest that Aroclor 1242 activates neutrophils to produce O2- by a mechanism that requires tyrosine kinase activity; however, heterotrimeric G-proteins are not likely to be involved.
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Affiliation(s)
- P K Tithof
- Department of Pharmacology and Toxicology, Institute for Environmental Toxicology, Michigan State University, East Lansing 48824, USA
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Cortijo J, Villagrasa V, Navarrete C, Sanz C, Berto L, Michel A, Bonnet PA, Morcillo EJ. Effects of SCA40 on human isolated bronchus and human polymorphonuclear leukocytes: comparison with rolipram, SKF94120 and levcromakalim. Br J Pharmacol 1996; 119:99-106. [PMID: 8872362 PMCID: PMC1915727 DOI: 10.1111/j.1476-5381.1996.tb15682.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
1. SCA40 (0.1 nM-0.1 mM) produced concentration-dependent suppression of the spontaneous tone of human isolated bronchus (-log EC50 = 6.85 +/- 0.09; n = 10) and reached a maximal relaxation similar to that of theophylline (3 mM). The potency (-log EC50 values) of SCA40 compared to other relaxants was rolipram (7.44 +/- 0.12; n = 9) > SCA40 > or = levcromakalim (6.49 +/- 0.04; n = 6) > SKF94120 (5.87 +/- 0.10; n = 9). 2. When tested against the activity of the isoenzymes of cyclic nucleotide phosphodiesterase (PDE) isolated from human bronchus, SCA40 proved highly potent against PDE III (-log IC50 = 6.47 +/- 0.16; n = 4). It was markedly less potent against PDE IV (4.82 +/- 0.18; n = 4) and PDE V (4.32 +/- 0.11; n = 4). 3. Human polymorphonuclear leukocytes (PMNs) stimulated with N-formylmethionyl-leucyl-phenylalanine (FMLP) produced a concentration-dependent superoxide anion generation and elastase release. SCA40 (1 nM-10 microM) produced a concentration-related inhibition of FMLP (30 nM approximately EC50)-induced superoxide production (-log IC50 = 5.48 +/- 0.10; n = 6) and elastase release (-log IC50 = 5.50 +/- 0.26; n = 6). Rolipram was an effective inhibitor of superoxide generation and elastase release (-log IC50 values approximately 8) while SKF94120 and levcromakalim were scarcely effective. 4. FMLP (30 nM) and thimerosal (20 microM) induced leukotriene B4 production and elevation of intracellular calcium concentration in human PMNs. The production of leukotriene B4 was inhibited by SCA40 in a concentration-related manner (-log IC50 = 5.94 +/- 0.22; n = 6) but SCA40 was less effective against the elevation of intracellular calcium. Rolipram was an effective inhibitor of leukotriene B4 synthesis (-log IC50 approximately 7) and intracellular calcium elevation (-log IC50 approximately 6) while SKF94120 and levcromakalim were scarcely effective. 5. It is concluded that SCA40 is an effective inhibitor of the inherent tone of human isolated bronchus. The bronchodilatation produced by SCA40 appears mainly related to PDE inhibition since the potency of SCA40 as a relaxant of human isolated bronchus was found to be close to its potency as inhibitor of PDE III activity isolated from human bronchus. In addition, SCA40 exhibited inhibitory effects on human PMN function stimulated by FMLP. These effects may be related to the ability of SCA40 to inhibit PDE IV from human PMNs while the contribution of PDE V inhibition is uncertain. We found no evidence of a role for levcromakalim-sensitive plasmalemmal K+-channels in human PMNs.
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Affiliation(s)
- J Cortijo
- Departamento de Farmacología, Facultad de Medicine y Odontología, Universitat de València, Spain
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Rosales C, Brown E. Signal transduction by neutrophil immunoglobulin G Fc receptors. Dissociation of intracytoplasmic calcium concentration rise from inositol 1,4,5-trisphosphate. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(18)42761-5] [Citation(s) in RCA: 60] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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5
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Calcium channel blockers nifedipine and diltiazem inhibit Ca2+ release from intracellular stores in neutrophils. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(18)45965-0] [Citation(s) in RCA: 60] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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Kosykh VA, Novikov DK, Trakht IN, Podrez EA, Victorov AV, Repin VS, Smirnov VN. Effect of chylomicron remnants on cholesterol metabolism in cultured rabbit hepatocytes: very low density lipoprotein and bile acid production. Lipids 1991; 26:799-805. [PMID: 1795601 DOI: 10.1007/bf02536161] [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
The interrelationship between very low density lipoprotein (VLDL) secretion and bile acid production was studied in primary culture of rabbit hepatocytes. Chylomicron remnants (CR) were added to the cultures to study their effect on VLDL secretion and bile acid production. After 24 hr preincubation of cells with CR (10-50 micrograms protein/mL), intercellular neutral lipid content was increased 1.5-4-fold in a dose-dependent manner. Neutral lipid accumulation was accompanied by a 70-90% reduction of [14C]acetate incorporation into cholesterol, while no stimulation of [14C]oleate incorporation into cholesteryl esters was observed. Incubation of cells with CR increased secretion of free cholesterol, triacylglycerol and apoproteins B and E in VLDL. Stimulation of VLDL cholesterol secretion was accompanied by a reduction of taurocholic acid synthesis. These data demonstrate the existence of an inverse relationship between secretion of VLDL cholesterol and bile acid production under conditions of effective uptake of triacylglycerol-rich CR by hepatocytes.
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Affiliation(s)
- V A Kosykh
- USSR Cardiology Research Center, Academy of Medical Sciences, Moscow
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7
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Thompson NT, Bonser RW, Tateson JE, Spacey GD, Randall RW, Hodson HF, Garland LG. A quantitative investigation into the dependence of Ca2+ mobilisation on changes in inositol 1,4,5-trisphosphate levels in the stimulated neutrophil. Br J Pharmacol 1991; 103:1592-6. [PMID: 1884113 PMCID: PMC1908335 DOI: 10.1111/j.1476-5381.1991.tb09832.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
1. The coupling of N-formyl-methionyl-leucyl-phenylalanine (fMet-Leu-Phe) receptor stimulation to Ca2+ mobilisation has been investigated in the human neutrophil by measuring the concentration-effect curves for inositol 1,4,5-trisphosphate (IP3) formation and Ca2+ mobilisation. 2. fMet-Leu-Phe-dependent mobilisation of intracellular Ca2+ has been monitored in fluo-3-loaded human neutrophils by measuring increases in the cytoplasmic free Ca2+ concentration ([Ca2+]i) in the presence of extracellular EGTA. Fluo-3 was used in preference to fura-2 because it was found to be more sensitive to the high Ca2+ levels seen in stimulated neutrophils. 3. fMet-Leu-Phe induced a rapid mobilisation of intracellular Ca2+ (EC50 = 2.9 +/- 0.1 nM) and increased [Ca2+]i to a maximum of 1286 +/- 184 nM. 4. The amount of IP3 in fMet-Leu-Phe-stimulated neutrophils was determined by competition with [3H]-IP3 for a specific IP3 binding protein isolated from bovine adrenocortical microsomes. Basal IP3 levels of 13.3 +/- 2.0 pmol per 10(7) cells were increased nearly 4 fold by maximally effective concentrations of fMet-Leu-Phe. 5. The EC50 for the IP3 response (95 +/- 18 nM) was much higher than that for mobilisation of intracellular Ca2+, such that only a doubling in the concentration of IP3 was required to fully mobilise intracellular Ca2+. 6. As a result of this relationship IP3 production was more sensitive than Ca2+ mobilisation to inhibition by demethoxyviridin, an inhibitor of phospholipase activation.
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Bengtsson T. Correlation between chemotactic peptide-induced changes in chlorotetracycline fluorescence and F-actin content in human neutrophils: a role for membrane-associated calcium in the regulation of actin polymerization? Exp Cell Res 1990; 191:57-63. [PMID: 2226651 DOI: 10.1016/0014-4827(90)90035-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Several observations indicate that the triggering event for receptor-mediated actin polymerization takes place in or close to the plasma membrane. Stimulation of human neutrophils with the chemotactic peptide formylmethionyl-leucyl-phenylalanine (fMet-Leu-Phe) causes rapid and transient changes in both chlorotetracycline (CTC) fluorescence and the cellular content of filamentous actin (F-actin), thus suggesting a regulatory role for membrane-bound calcium in actin polymerization. In the present study, tetracaine, a proposed antagonist to membrane-bound calcium, totally inhibited the rebinding of the membrane calcium released by fMet-Leu-Phe. This was accompanied by a magnified and sustained increase in the cellular content of F-actin. In agreement, N-ethylmaleimide, an inhibitor of motile functions, completely abolished the fMet-Leu-Phe-triggered changes in both CTC fluorescence and F-actin content and rapidly reversed the responses when added after the peptide. The tumor promoter phorbol-12-myristate-13-acetate, caused only small changes in CTC fluorescence and F-actin content, and reduced a subsequent fMet-Leu-Phe-induced CTC response and actin polymerization. Inhibition of the breakdown of phosphatidylinositol 4,5-bisphosphate, by calcium depletion, had no significant effects on the fMet-Leu-Phe-induced CTC response and alterations in F-actin content, whereas pretreatment with pertussis toxin totally inhibited both these responses. Consequently, the strong correlation between changes in CTC fluorescence and F-actin content, found in this study, suggests a triggering or modulating role of membrane-associated calcium on actin polymerization in human neutrophils.
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Affiliation(s)
- T Bengtsson
- Department of Medical Microbiology, University of Linköping, Sweden
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9
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Aaku E, Sorsa T, Wilkström M. Human immunoglobulin G potentiates superoxide production induced by chemotactic peptides and causes degranulation in isolated human neutrophils. BIOCHIMICA ET BIOPHYSICA ACTA 1990; 1052:243-7. [PMID: 2159345 DOI: 10.1016/0167-4889(90)90217-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Neutrophils are major cellular mediators of host defense and inflammation. They can be activated to produce superoxide and to release the contents of their granules to the extracellular space. We observed that monomeric human immunoglobulin G (IgG) sensitizes these cells to the chemotactic peptide N-formylmethionylleucylphenylalanine (fMLP). In cells submaximally stimulated by fMLP this enhancement was especially prominent. With saturating fMLP concentrations, the rate of O2- production was still about twice that in the control. No synergy with other activators (phorbol myristate acetate, concanavalin A) was observed. Binding of fMLP to the cells was decreased by IgG, resembling the effect of cytochalasin B. IgG did not induce O2- production on its own, but it stimulated degranulation of the neutrophils.
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Affiliation(s)
- E Aaku
- Department of Medical Chemisty, University of Helsinki, Finland
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Nath J, Powledge A, Wright DG. Studies of Signal Transduction in the Respiratory Burst-associated Stimulation of fMet-Leu-Phe-induced Tubulin Tyrosinolation and Phorbol 12-Myristate 13-Acetate-induced Posttranslational Incorporation of Tyrosine into Multiple Proteins in Activated Neutrophils and HL-60 Cells. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(19)85020-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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11
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Korchak HM, Vosshall LB, Zagon G, Ljubich P, Rich AM, Weissmann G. Activation of the neutrophil by calcium-mobilizing ligands. I. A chemotactic peptide and the lectin concanavalin A stimulate superoxide anion generation but elicit different calcium movements and phosphoinositide remodeling. J Biol Chem 1988. [DOI: 10.1016/s0021-9258(18)37926-2] [Citation(s) in RCA: 59] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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12
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Rossi AG, McMillan RM, MacIntyre DE. Agonist-induced calcium flux, phosphoinositide metabolism, aggregation and enzyme secretion in human neutrophils. AGENTS AND ACTIONS 1988; 24:272-82. [PMID: 2845744 DOI: 10.1007/bf02028283] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Formyl-methionyl-leucyl-phenylalanine (FMLP), platelet activating factor (PAF) and leukotriene B4 (LTB4) are potent activators of human neutrophils. Using human neutrophils prelabelled with the fluorescent indicator dye, Quin 2, or with [32P]-orthophosphate, we examined the effects of these stimuli on intracellular free calcium concentration, [Ca2+]i, and on various indices of phosphoinositide metabolism, including [32P]-phosphatidic acid (PtdA) formation. The concentration-dependence of the observed changed in [Ca2+]i or [32P]-PtdA were then compared to stimulus-induced aggregation and enzyme release (beta-N-acetylglucosaminidase (NAG) and lysozyme). FMLP, PAF and LTB4 caused a concentration-dependent elevation of [Ca2+]i, aggregation and enzyme release. However, unlike FMLP and PAF, LTB4 (less than or equal to 2.5 microM) did not cause significant formation of [32P]-PtdA. The concentration response curves for agonist-induced elevation of [Ca2+]i lie to the left of those for aggregation and enzyme release. FMLP and PAF also caused an elevation of [Ca2+]i at concentrations lower than those required to elicit [32P]-PtdA formation. These observations suggest that [Ca2+]i elevation per se cannot mediate human neutrophil functional responses to FMLP, PAF and LTB4. Consequently there may exist other mediator(s) that act in concert with [Ca2+]i or are triggered by [Ca2+]i elevation to promote human neutrophil activation. Both the elevation of [Ca2+]i and the formation of these putative mediator(s) in response to LTB4 apparently occur independently of inositol phospholipid hydrolysis.
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Affiliation(s)
- A G Rossi
- Department of Pharmacology, University of Glasgow, Scotland, UK
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13
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Banks P, Barker MD, Burton DR. Recruitment of actin to the cytoskeletons of human monocyte-like cells activated by complement fragment C5a. Is protein kinase C involved? Biochem J 1988; 252:765-9. [PMID: 3421921 PMCID: PMC1149213 DOI: 10.1042/bj2520765] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
U-937 cells differentiated by exposure to dibutyryl cyclic AMP respond to complement fragment C5a with a marked increase in cytoskeletal F-actin, which can be detected by fluorescence-activated cell sorting (f.a.c.s.) analysis of their rhodamine phalloidin-stained cytoskeletons. The C5a-induced increase in F-actin content can be prevented by prior exposure of the cells to cytochalasin B and pertussis toxin. It is insensitive to removal of extra cellular Ca2+, to cholera toxin or to neomycin. Phorbol myristate acetate (PMA), an activator of protein kinase C, does not induce actin polymerization in the differentiated cells. Both C5a and PMA stimulate superoxide production. The action of C5a on superoxide formation is also inhibited by neomycin, a phospholipase inhibitor. These results suggest that the cytoskeletal response to C5a requires activation of a G protein, but probably does not involve phospholipase C and protein kinase C, and is not highly dependent on the availability of Ca2+. Phospholipase C and kinase C may, however, be components of the pathway leading from C5a binding to superoxide production.
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Affiliation(s)
- P Banks
- Department of Biochemistry, University of Sheffield, U.K
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14
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Viktorov AV, Dank EK, Kuznetsov VA, Ter-Simonyan VG, Yurkiv VA. Phosphoinositide breakdown and diacylglycerol formation in human platelets under the influence of lipopolysaccharide toxin. Bull Exp Biol Med 1988. [DOI: 10.1007/bf00835745] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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15
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Ability of lipopolysaccharide toxin to enhance the functional response of human platelets to thrombin stimulation. Bull Exp Biol Med 1988. [DOI: 10.1007/bf00835685] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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16
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Gomez-Cambronero J, Molski TF, Becker EL, Sha'afi RI. The diacylglycerol kinase inhibitor R59022 potentiates superoxide production but not secretion induced by fMet-Leu-Phe: effects of leupeptin and the protein kinase C inhibitor H-7. Biochem Biophys Res Commun 1987; 148:38-46. [PMID: 2823810 DOI: 10.1016/0006-291x(87)91073-4] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The addition of low concentrations of the chemotactic factor fMet-Leu-Phe to rabbit neutrophils in the absence of cytochalasin B produces very little superoxide. This level of superoxide can be greatly increased in neutrophils pretreated for 30 min with 10 microM of the diacyl-glycerol kinase inhibitor R59022. This potentiation occurs also in the presence of cytochalasin B. In addition, while the small level of superoxide generated by fMet-Leu-Phe is not inhibited by the protein kinase C inhibitor 1-(5-isoquinoline-sulfonyl)-2-methyl piperazine (H-7), the increase by R59022 is completely abolished by this compound. In addition, this increase can be potentiated further by leupeptin. Unlike superoxide generation, the release of lysozyme or N-acetyl-beta-glucosaminidase produced by fMet-Leu-Phe is not stimulated by R59022. The results presented here suggest that stimulation of the oxidative burst requires the generation and the maintenance of a sufficient amount of diacylglycerol and/or the rearrangement of the cytoskeleton such as the inhibition of actin polymerization. Furthermore, the membrane-associated form of protein kinase C is the one responsible for the activation of the oxidative burst. The relationship between protein kinase C activation and the stimulated oxidative burst and the physiological role of chemotactic factors in the functions of the neutrophils are discussed.
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Affiliation(s)
- J Gomez-Cambronero
- Department of Physiology and Pathology, University of Connecticut Health Center, Farmington 06032
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Styrt B, Schwartz MA, Klempner MS. Linkage between neutrophil degranulation and calcium discharge. Biochem Biophys Res Commun 1987; 146:1386-91. [PMID: 3619936 DOI: 10.1016/0006-291x(87)90803-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Calcium flux across organelle and plasma membranes is an important event in neutrophil activation. We measured calcium discharge into the media from neutrophils stimulated with formyl-methionyl-leucyl-phenylalanine after treatment with cytochalasin b. Cytochalasin markedly potentiated calcium efflux from stimulated neutrophils, and similarly promoted release of lysosomal enzymes into the media. Colchicine neither reproduced nor modified the cytochalasin effect. Neutrophil cytoplasts discharged very little calcium in response to stimulation, and discharge was not significantly altered by cytochalasin b. These findings indicate that neutrophil degranulation is accompanied by efflux of calcium into the media, and suggest that the neutrophil granules constitute a source of mobilizable calcium which could be used to modify the extracellular microenvironment.
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18
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English D, Debono DJ, Gabig TG. Relationship of phosphatidylinositol bisphosphate hydrolysis to calcium mobilization and functional activation in fluoride-treated neutrophils. J Clin Invest 1987; 80:145-53. [PMID: 3036911 PMCID: PMC442212 DOI: 10.1172/jci113040] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Sodium fluoride (20 mM) effected rapid hydrolysis of phosphatidylinositol bisphosphate (PIP2) in human neutrophils. Intracellular free Ca2+ levels increased after PIP2 hydrolysis but before respiratory burst activation. Both the increase in intracellular free Ca2+ levels and the extent of functional activation were dependent on the availability of extracellular Ca2+. The rate of F(-)-stimulated PIP2 hydrolysis, however, was not affected when the rise in cytosolic Ca2+ was severely limited by depletion of extracellular Ca2+. Fluoride caused the specific hydrolysis of PIP2 in isolated neutrophil plasma membranes. This effect occurred in the presence of low levels of available Ca2+ and was accompanied by the release of inositol phosphates. We conclude that PIP2 hydrolysis is an early event in the response of neutrophils to F-. This response is not Ca2+-regulated but may lead to an influx of Ca2+ from the extracellular medium. Activation of a PIP2-specific phospholipase independent of a change in cytosolic free Ca2+ levels may be the initial event in the stimulus-response pathway triggered by fluoride.
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19
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Nourshargh S, Hoult JR. Divergent effects of co-carcinogenic phorbol esters and a synthetic diacylglycerol on human neutrophil chemokinesis and granular enzyme secretion. Br J Pharmacol 1987; 91:557-68. [PMID: 3475147 PMCID: PMC1853549 DOI: 10.1111/j.1476-5381.1987.tb11249.x] [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: 01/05/2023] Open
Abstract
The effects of two co-carcinogenic phorbol esters (phorbol myristate acetate (PMA) and phorbol dibutyrate (PDBu] and a synthetic diacylglycerol (OAG, 1-oleoyl-2-acetyl-glycerol), which all stimulate protein kinase C, were compared with two inactive phorbol compounds (4 alpha-phorbol and 4 alpha-phorbol didecanoate (4 alpha-PDD)) on three functional properties of stimulated human polymorphonuclear leukocytes (PMNs): release of granular enzymes lysozyme and beta-glucuronidase, chemokinesis, and changes in cytoplasmic free calcium [Ca2+]i. PMA, PDBu and the diacylglycerol, OAG, all caused a dose-dependent and slow (max by 15 min) release of small amounts of lysozyme with much less beta-glucuronidase and no release of cytoplasmic lactate dehydrogenase. Release was unaffected by removal of extracellular Ca2+. PMA, PDBu and OAG inhibited random movement of the cells, did not cause chemokinesis and induced a slow reduction in the basal [Ca2+]i, as measured by the quin-2 method. PMA, PDBu and OAG increased the capacity of five independently-acting stimulants (N-formyl-Met-Leu-Phe, leukotriene B4, C5a des-Arg, platelet activating factor and A23187) to cause release of lysozyme and beta-glucuronidase but strongly inhibited PMN chemokinesis induced by the same five agents and reduced the stimulant-induced increases in [Ca2+]i. PMA was always more potent than PDBu and much more potent than OAG in eliciting these stimulatory or inhibitory effects on human PMNs. In all tests, 4 alpha-phorbol and 4 alpha-PDD were inactive. The results confirm that stimulation of the diacylglycerol/protein kinase C system in human PMN, either by active phorbol esters or the synthetic diacylglycerol, causes bidirectional effects on human PMN function. In particular, activation of the C-kinase causes inhibition of stimulated neutrophil motility, whereas the secretory functions of the cells are enhanced.
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20
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Smith C, Uhing R, Snyderman R. Nucleotide regulatory protein-mediated activation of phospholipase C in human polymorphonuclear leukocytes is disrupted by phorbol esters. J Biol Chem 1987. [DOI: 10.1016/s0021-9258(18)45546-9] [Citation(s) in RCA: 134] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
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21
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Rossi F. The O2- -forming NADPH oxidase of the phagocytes: nature, mechanisms of activation and function. BIOCHIMICA ET BIOPHYSICA ACTA 1986; 853:65-89. [PMID: 3021215 DOI: 10.1016/0304-4173(86)90005-4] [Citation(s) in RCA: 518] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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22
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Della Bianca V, De Togni P, Grzeskowiak M, Vicentini LM, Di Virgilio F. Cyclic AMP inhibition of phosphoinositide turnover in human neutrophils. BIOCHIMICA ET BIOPHYSICA ACTA 1986; 886:441-7. [PMID: 3011119 DOI: 10.1016/0167-4889(86)90180-1] [Citation(s) in RCA: 67] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The effect of increased intracellular levels of cyclic AMP on phosphoinositide metabolism was studied in human neutrophils stimulated with fMet-Leu-Phe. Intracellular cyclic AMP was raised by preincubation either with dibutyryl cyclic AMP and theophylline or with prostaglandin E1. Concentrations of dibutyryl cyclic AMP and theophylline fully inhibitory for the metabolic responses inhibited phosphoinositide breakdown and phosphatidic acid formation to a large extent. The accumulation of the water-soluble inositol phosphates was also measured. In agreement with the data obtained on the phospholipids, inositol phosphate generation was found to be severely, though not completely, reduced. Treatment with dibutyryl cyclic AMP and theophylline also inhibited resynthesis of membrane inositol lipids. Treatment with prostaglandin E1 had a similar, though less, marked effect on inositol lipid turnover, which was parallel with a smaller inhibition of metabolic responses. We therefore suggest that the elevation of intracellular cyclic AMP mainly affects neutrophil responses by inhibiting the phosphoinositide cycle.
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Vicentini LM, Ambrosini A, Di Virgilio F, Meldolesi J, Pozzan T. Activation of muscarinic receptors in PC12 cells. Correlation between cytosolic Ca2+ rise and phosphoinositide hydrolysis. Biochem J 1986; 234:555-62. [PMID: 3013159 PMCID: PMC1146607 DOI: 10.1042/bj2340555] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The intracellular signals generated by carbachol activation of the muscarinic receptor [release of inositol phosphates as a consequence of phosphoinositide hydrolysis and rise of the cytosolic Ca2+ concentration ([Ca2+]i, measured by quin2)] were studied in intact PC12 pheochromocytoma cells that had been differentiated by treatment with nerve growth factor. When measured in parallel samples of the same cell preparation 30 s after receptor activation, the release of inositol trisphosphate and of its possible metabolites, inositol bis- and mono-phosphate, and the [Ca2+]i rise were found to occur with almost superimposable carbachol concentration curves. At the same time carbachol caused a decrease in the radioactivity of preloaded phosphatidylinositol 4,5-bisphosphate, the precursor of inositol trisphosphate. Neither the inositol phosphate nor the [Ca2+]i signal was modified by preincubation of the cells with either purified Bordetella pertussis toxin or forskolin, the direct activator of adenylate cyclase. Both signals were partially inhibited by dibutyryl cyclic AMP, especially when the nucleotide analogue was applied in combination with the phosphodiesterase inhibitors RO 201724 and theophylline. The latter drug alone profoundly inhibited the carbachol-induced [Ca2+]i rise, with only minimal effect on phosphoinositide hydrolysis. Because of the diverging results obtained with forskolin on the one hand, dibutyryl cyclic AMP and phosphodiesterase inhibitors on the other, the effects of the latter drugs are considered to be pharmacological, independent of the intracellular cyclic AMP concentration. Two further drugs tested, mepacrine and MY5445, inhibited phosphoinositide hydrolysis at the same time as the 45Ca2+ influx stimulated by carbachol. Taken together, our results concur with previous evidence obtained with permeabilized cells and cell fractions to indicate phosphatidylinositol 4,5-bisphosphate hydrolysis and [Ca2+]i rise as two successive events in the intracellular transduction cascade initiated by receptor activation. The strict correlation between the carbachol concentration curves for inositol trisphosphate generation and [Ca2+]i rise, and the inhibition by theophylline of the Ca2$ signal without major effects on inositol phosphate generation, satisfy important requirements of the abovementioned interpretation.
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Verghese MW, Smith CD, Snyderman R. Role of guanine nucleotide regulatory protein in polyphosphoinositide degradation and activation of phagocytic leukocytes by chemoattractants. J Cell Biochem 1986; 32:59-69. [PMID: 3021789 DOI: 10.1002/jcb.240320107] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Leukocyte activation by chemoattractants provides an important model to study the biochemical mechanisms of stimulus-response coupling in these cells. Well-defined chemotactic factors induce readily quantifiable responses in phagocytic leukocytes. These include directed migration and the production and release of toxic substances including oxygen radicals and lysosomal enzymes. The development of radiolabeled synthetic oligopeptides with potent chemotactic activity allowed the demonstration of chemoattractant receptors on polymorphonuclear leukocytes (PMNs) as well as macrophages. In membrane preparations from these cells, these receptors exist in high- and low-affinity states which are regulated by guanosine di- and triphosphates. This suggested that chemoattractant receptors interact with guanine nucleotide regulatory proteins (N or G proteins). Although chemoattractants elicit a rapid but transient increase in intracellular cAMP levels, they neither stimulate nor inhibit membrane-bound adenylate cyclase, suggesting a novel role for N proteins in certain receptor-transduction mechanisms. Stimulation of phagocytes by chemoattractants is also associated with a rapid increase in cytosolic Ca2+ concentrations ([ Ca2+]i) which appears to result from the production of inositol 1,4,5-triphosphate (IP3) as a consequence of the diesteric cleavage of phosphatidylinositol 4,5-bisphosphate (PIP2). Treatment of phagocytes with pertussis toxin (PT), which ADP-ribosylates and thereby inactivates certain N proteins, abolishes the cells' responsiveness to chemoattractants. More direct evidence for a role of a PT-sensitive N protein in leukocyte activation was provided by the demonstration that chemoattractants stimulate the hydrolysis of PIP2 in PMN membranes only in the presence of GTP. This receptor-mediated hydrolysis of PIP2 is not observed in plasma membranes prepared from PT-treated PMNs. Therefore, these studies suggest that occupancy of chemoattractant receptors activates a PT-sensitive N protein. The activated N protein shifts the Ca2+ requirement for phospholipase C activity from supraphysiological levels to ambient cytosolic Ca2+ concentrations. Cleavage of PIP2 results in the formation of the second messenger molecules, IP3 and 1,2-diacylglycerol, which can initiate cellular activation. These messengers also seem to activate responses which feed back to attenuate receptor stimulation of phospholipase.
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Activation of human platelets by ADP causes a rapid rise in cytosolic free calcium without hydrolysis of phosphatidylinositol-4,5-bisphosphate. Biochem Biophys Res Commun 1985; 129:958-64. [PMID: 2990473 DOI: 10.1016/0006-291x(85)91984-9] [Citation(s) in RCA: 90] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Phosphatidylinositol-4,5-bisphosphate decreased 40% within 10 seconds after the addition of thrombin to platelets. This thrombin-induced loss was accompanied by a corresponding increase of inositol phosphates. In contrast, within the first 60 seconds after exposure of platelets to ADP there was no detectable change in the amounts of phosphatidylinositol-4,5-bisphosphate or inositol phosphates. Both thrombin and ADP, however, caused a very rapid rise of cytosolic free calcium, as measured by Quin-2. The magnitude of this rise of calcium was similar for the two agonists. These results suggest that in platelets, agonist stimulation may lead to increased cytosolic free calcium independently of phosphatidylinositol-4,5-bisphosphate degradation.
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