Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0043167 (pertussis)
 19,595 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The pluripotent human erythroleukaemia cell line, HEL, possesses erythrocytic, megakaryocytic and macrophage-like properties. With respect to signal transduction, HEL cells have been used as a model system for platelets, but little attention has been paid to their phagocytic properties. We studied the effects of various receptor agonists on the intracellular free Ca2+ concentration ([Ca2+]i) in HEL cells. Thrombin, platelet-activating factor (PAF), ATP, UTP, prostaglandins E1 and E2 (PGE1 and PGE2), the PGE2 analogue sulprostone and the stable PGI2 analogues iloprost and cicaprost increased [Ca2+]i. ADP was less effective than ATP, and UDP was unable to increase [Ca2+]i. The increases in [Ca2+]i induced by thrombin, PAF, ATP, UTP, iloprost and cicaprost were pertussis toxin-insensitive, whereas the increases induced by PGE2 and sulprostone were completely inhibited by the toxin. The increase in [Ca2+]i induced by PGE1 was partially inhibited by pertussis toxin. PGE2 did not desensitize the increase in [Ca2+]i induced by iloprost, and vice versa. PGE1 desensitized the response to PGE2 and iloprost but not vice versa. Adrenaline potentiated the iloprost- but not the PGE2-induced rise in [Ca2+]i. The phorbol ester phorbol 12-myristate 13-acetate completely blocked the rise in [Ca2+]i induced by ATP and PGE1, whereas the increases induced by thrombin and PAF were only partially inhibited. Agonists increased [Ca2+]i through release from internal stores and sustained Ca2+ influx. Thrombin stimulated Mn2+ influx, which was blocked by Ni2+. Diltiazem, isradipine, gramicidin and 1-(beta-[3-(4-methoxyphenyl)propoxy]-4-methoxyphenethyl)-1H-imidazole hydrochloride (SK&F 96365) did not affect agonist-induced rises in [Ca2+]i. HEL cells contained substantial amounts of beta-glucuronidase which, however, could not be released, and they did not aggregate or generate superoxide. Our data suggest that: (1) HEL cells possess nucleotide receptors with properties similar to those of phagocytes; (2) they possess receptors for PGE2 and PGI2, and PGE1 is an agonist at both receptors; (3) agonist-induced increases in [Ca2+]i are mediated through pertussis toxin-sensitive as well as -insensitive signal transduction pathways; and (4) agonists increase [Ca2+]i by mobilization from internal stores and influx from the extracellular space through cation channels with properties similar to those of phagocytes and platelets.
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PMID:Receptor-mediated increases in cytosolic Ca2+ in the human erythroleukaemia cell line involve pertussis toxin-sensitive and -insensitive pathways. 131 May 89

The human erythroleukemia cell line (HEL) has been used as a model system for studying signal transduction processes as they might relate to platelet/megakaryocyte function. We were interested in examining the role of thrombin in the regulation of adenylyl cyclase in this cell line. As opposed to its predominantly inhibitory effects on cyclic AMP production in platelets or in membranes from HEL cells, our initial experiments in intact HEL cells revealed that thrombin markedly potentiated the cyclic AMP response to prostaglandin E1 (2.9 +/- 0.2-fold), prostacyclin (1.9 +/- 0.2-fold) and carbacyclin (2.5 +/- 0.5-fold), measured either by radioimmunoassay or by the [3H]adenine preloading procedure. Thrombin, although ineffective alone, also potentiated cyclic AMP production stimulated by vasoactive intestinal peptide (1.6 +/- 0.2-fold), cholera toxin (3.0 +/- 0.6-fold) and AIF4- (2.3 +/- 0.6-fold), but not by forskolin (0.9 +/- 0.1-fold). The thrombin effect 1) produced an increase in the efficacy of the prostaglandins with no change in potency; 2) was long-lived; 3) required the proteolytic activity of thrombin; 4) was insensitive to pertussis toxin; and 5) was at least partially mimicked by trypsin, extracellular ATP and UTP, platelet activating factor and activators of protein kinase C. Down-regulation of protein kinase C or pre-exposure to the protein kinase inhibitor staurosporine blocked the potentiating effect. Together, these results suggest that in HEL cells, the mechanism of thrombin potentiation of cyclic AMP production may involve alterations in the interaction between stimulatory guanine nucleotide binding protein and the catalytic subunit of adenylyl cyclase, possibly involving protein kinase C-mediated phosphorylation.
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PMID:Potentiation of cyclic adenosine monophosphate production by thrombin in the human erythroleukemia cell line, HEL. 133 12

To investigate whether GTP concentrations can be a regulatory step in exocytotic hormone secretion, we treated isolated rat islets with mycophenolic acid (MPA) or mizoribine, two selective inhibitors of de novo GTP synthesis. When islets were cultured overnight in purine-free medium containing the drug, MPA reduced GTP levels by up to 81 +/- 1%; guanine circumvented this block via the nucleotide "salvage" pathway. MPA concomitantly inhibited glucose (16.7 mM)-induced insulin secretion in batch-type incubations (or perifusions), by up to 68% at 50 micrograms/ml. Although the inhibition of secretion occurred over a similar concentration range as the reduction in total GTP content, the two variables were not directly correlated. However, the secretory effects also were prevented by adding guanine, but not hypoxanthine or xanthine, to the culture medium. Similar results for GTP content and insulin release were seen using mizoribine. Insulin content was modestly (-18%) reduced by MPA but indices of fractional release (release/insulin content) were also markedly impaired. Although MPA also reduced ATP levels more modestly (-39%) and increased UTP (+87%), these were not the cause of the secretory defect since adenine restored ATP and UTP nearly to normal, but did not alter the reduction in GTP content or insulin secretion. MPA also inhibited secretion induced by amino acid or by a phorbol ester but had virtually no effect on release induced by a depolarizing concentration of K+, suggesting that GTP depletion does not merely impede Ca+ influx or directly block Ca(2+)-activated exocytosis. However, a severe reduction of GTP content did not prevent the pertussis toxin-sensitive inhibition of insulin release induced by epinephrine, suggesting that the function of heterotrimeric GTP-binding proteins is not limited by ambient GTP concentrations. Although these studies do not elucidate the exact site(s) in the exocytotic cascade which depend on intact GTP stores, they do provide the first direct evidence that GTP is required (and can be rate limiting) for insulin release.
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PMID:Selective inhibitors of GTP synthesis impede exocytotic insulin release from intact rat islets. 135 88

We studied the regulation of arachidonic acid (AA) release by guanosine 5'-O-(3-thiotriphosphate (GTP gamma S) and Ca2+ in electropermeabilized HL60 granulocytes. Stimulation of AA release by GTP gamma S and Ca2+ was mediated by phospholipase A2 (PLA2) and required the presence of MgATP (EC50: 100-250 microM). The nucleotide effects were Ca(2+)-dependent (maximal effects detected at 1 microM free cation). UTP and ATP gamma S, which stimulate AA release in intact HL60 granulocytes with potencies and efficacies similar to those of ATP, were ineffective in supporting the effects of GTP gamma S in electropermeabilized cells. Pretreatment with pertussis toxin affected stimulation of AA release by ATP in intact cell, without altering the nucleotide effects in permeabilized cells. We observed the protein kinase C-dependent phosphorylation of PLA2 in permeabilized HL60 granulocytes, together with a correlation between the effects of phorbol esters and staurosporine on this reaction and on AA release. ATP-independent activation of PLA2 by GTP gamma S and/or Ca2+ was measured in subcellular fractions prepared from HL60 granulocytes. These data appear consistent with a model in which PLA2 activity in resting HL60 granulocytes is subjected to an inhibitory constraint that prevents its activation by Ca2+ and G-proteins. Removal of this constraint, either by the protein kinase C-dependent phosphorylation of the enzyme in vivo or physical disruption of the regulatory assembly (e.g. by N2 cavitation), allows its activation by Ca2+ and G-proteins.
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PMID:Phosphorylation-dependent regulation of phospholipase A2 by G-proteins and Ca2+ in HL60 granulocytes. 146 9

1. The addition of ATP to cultured bovine aortic endothelial cells induced the increase in intracellular free calcium concentration ([Ca2+]i) and thereby activated the sodium/proton exchanger and the prostacyclin production in a similar dose-dependent manner, as observed by the addition of ATP. 2. Other nucleoside triphosphates also activated the cells and the potency orders of the nucleotides were ATP greater than UTP greater than ITP greater than CTP greater than GTP for all the responses. 3. Pretreatment of the cells with UTP desensitized the response to ATP and the pretreatment of ATP desensitized the response to UTP. 4. The responses to ATP and UTP were inhibited by neither pertussis nor cholera toxin. 5. The receptor for UTP, however, may be a distinct pyrimidinoceptor different from the purinoceptor of the cells for ATP, because the 50% effective concentration of UDP was much larger than that of UTP, while ATP and ADP were essentially equipotent ligands to the endothelial cells.
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PMID:Activation of cultured bovine aortic endothelial cells by extracellular pyrimidine triphosphate. 164 13

Stimulation of phagocytic cells with micromolar concentrations of extracellular ATP primes the production of toxic oxygen metabolites in response to chemoattractants and independently activates a secretory response in vitro. It is hypothesized that extracellular ATP derived from platelet storage granules and damaged endothelium at sites of localized tissue damage or infection may potentiate the pro-inflammatory effects of phagocytic cells in vivo. ATP-dependent functional responses in the phagocyte appear to be due to stimulation of putative P2 purinoreceptors that are coupled to the activation of a phospholipase C via a pertussis toxin-sensitive G-protein. The existence in nature of at least four subtypes of P2 purinoreceptors has been proposed based on the rank order of potency of nucleotide analogs of ATP studied in a variety of cell types. However, no studies involving the structural identification and characterization of the putative receptors have been reported. We have used the Xenopus oocyte expression system to demonstrate acquired adenosine 5'-(thio) triphosphate (ATP gamma S) responsiveness in oocytes injected with mRNA from the promyelocytic leukemia cell line HL60 by measuring the accelerated efflux of intracellular calcium. Two peaks of ATP gamma S responsiveness (Peak I and Peak II) were detected in sucrose gradient fractionated RNA that corresponded to transcript sizes of 4 and 6 kilobases and that were distinct from a third peak previously shown to be enriched in formyl peptide chemoattractant receptor activity. Peak I and Peak II RNA endowed receptor activity in the oocyte that was pharmacologically indistinguishable: ADP and AMP were inactive whereas UTP and ITP exhibited activity that was similar in potency to that of ATP gamma S. Both Peak I and Peak II ATP gamma S-dependent activity was inhibited by pertussis toxin. These data strongly support the concept of phagocytic cell receptors for extracellular nucleotide triphosphates whose ligand specificity is distinct from all other previously described P2 purinoreceptor subtypes, with the exception of the P2 receptor described in Ehrlich ascites tumor cells, by virtue of the ineffectiveness of ADP as a stimulus. These receptors are most likely composed of a single polypeptide chain that can be expressed in the Xenopus oocyte in a functional form regulated by a pertussis toxin-sensitive G-protein.
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PMID:Characterization of phagocyte P2 nucleotide receptors expressed in Xenopus oocytes. 169 46

When applied extracellularly in the micromolar range, ATP and related compounds induced a positive inotropy in the rat papillary muscle. This was also true in the rat auricle after pertussis toxin treatment. Then, in both tissues, ATP further increased the contraction after a maximal beta-adrenergic stimulation. The increase in contractile force could be related to the increase in the calcium current. The L-type calcium current was measured by whole-cell patch-clamp recording in single cells isolated from the rat ventricle after the sodium and potassium currents were inhibited by tetrodotoxin and cesium, respectively. When added alone, 10 microM ATP increased the calcium current by 60%. Adenosine 5'-O-(3-thiotriphosphate) was also able to increase calcium current. Adenosine was much less effective, and GTP, UTP, CTP, and ITP were without effect. A similar increase in calcium current was observed when ATP was added in addition to a maximal stimulation by a beta-adrenergic agonist or after internal perfusion with cyclic AMP. However, this increase was preceded by a transient decrease whose origin could not be attributed to a P1-purinergic agonistic effect of ATP. The transient decrease was not elicited by adenosine or in a magnesium-free HEPES solution and was not suppressed after pertussis toxin treatment. This effect appeared related to the variations in the holding current also observed upon ATP application. Together with vasodilation, ATP and adenine compounds induced positive inotropy. The latter effect could be attributed in part to the increase in calcium current and was independent of cyclic AMP. Both effects are complementary with the beta-adrenergic stimulation and can help healthy cells to compensate the failing zone from which ATP could be released.
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PMID:The mechanism of positive inotropy induced by adenosine triphosphate in rat heart. 169 71

Extracellular nucleotides, acting through P2 purinoceptors, have been implicated in the regulation of ion transporting epithelia, including salivary gland acini. Multiple P2 purinoceptor subtypes have been suggested, including P2X, P2Y and P2U (or nucleotide) subtypes, as well as the P2Z subtype found in rat parotid acinar cells. We investigated responses to ATP, ATP analogs and UTP in transformed human submandibular gland duct cells (HSG-PA), in order to compare duct cell purinoreceptors with those in acinar cells. ATP, UTP and some ATP analogs increased, with different potencies, inositol phosphate accumulation, calcium mobilization and potassium efflux. Nucleotide-stimulated calcium mobilization occurred in the absence of, but was enhanced by, extracellular calcium, and maximal potassium efflux required extracellular calcium. UTP and ATP demonstrated equal potencies of about 1 microM and similar efficacies in eliciting these responses, and identical rank orders of potency for stimulating calcium mobilization and potassium efflux were obtained: UTP = ATP greater than ATP gamma S greater than ADP greater than ADP beta S, with alpha,beta-methylene-ATP and 2-methylthio-ATP having little or no effect. Agents reported to block nucleotide effects in parotid acini were ineffective in HSG-PA cells, and experiments in Mg(++)- and Ca(++)-free medium did not indicate that a form of ATP other than MgATP was the active species at the HSG-PA purinoceptor. The extracellular nucleotide effects were not altered by pertussis toxin. These results indicate the presence of a P2U or nucleotide receptor subtype in HSG-PA submandibular duct cells distinguishable from the P2Z purinoceptor of rat parotid acinar cells, suggesting involvement of multiple nucleotide receptor subtypes in salivary gland regulation.
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PMID:Functional studies in the human submandibular duct cell line, HSG-PA, suggest a second salivary gland receptor subtype for nucleotides. 176 82

Since human polymorphonuclear neutrophils (PMN) exposed to ATP or its poorly hydrolyzable analogue, adenosine-5'-O-(3-thiotriphosphate) (ATP gamma S), respond with increases in intracellular calcium and enhanced O2- responses to the chemotactic peptide N'-formyl-Met-Leu-Phe (fMLP), we systematically evaluated responses of PMN to various nucleotides. The P2X and P2Y receptor agonists, 2-methylthioadenosine triphosphate and beta, gamma-methyleneadenosine triphosphate, failed to induce increases in intracellular calcium and did not desensitize PMN to increases in intracellular calcium induced by ATP gamma S. Since it has been suggested that P2Z receptor occupancy with the ATP4- species caused nonselective increases in cell permeability, the ability of ATP to induce increases in intracellular calcium was evaluated in the presence and absence of extracellular Ca2+ and Mg2+. In the presence of these cations, 5-fold greater concentrations of ATP were required. The effects of ATP4- were not associated with changes in cell membrane permeability. This suggests that ATP4- is the active species but that its effect on PMN is not linked to a nonselective increase in permeability of the cell membrane. With respect to responses of PMN to purine and pyrimidine nucleotides as defined by increases in intracellular calcium, the rank order of potency for the nucleotides was ATP = UTP greater than ATP gamma S greater than or equal to ITP greater than GTP greater than or equal to CTP. These responses were blocked by pretreatment of PMN with pertussis toxin. Prior exposure of PMN to ATP gamma S blocked cellular responses (calcium increases) to these nucleotides but not to fMLP. Likewise, exposure of PMN to any nucleotides blocked subsequent cellular responses to ATP gamma S but not to fMLP. These data support the concept that nucleotide responses of PMN utilize either a common receptor or a common signal transduction pathway involving a guanine nucleotide binding protein in events leading to elevations in intracellular calcium. Nucleotide interaction with PMN does not follow the established pattern of responses associated with P2X or P2Y purinergic receptor occupancy.
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PMID:Nucleotide responses of human neutrophils. 184 54

Following a previous report on detection of muscarinic receptors in myelin with the implied presence of G proteins, we now demonstrate by more direct means the presence of such proteins and their quantification. Using [35S]guanosine 5'-O-(3-thiotriphosphate) ([35S]GTP gamma S) as the binding ligand, purified myelin from bovine brain was found to contain approximately half the binding activity of whole white matter (138 +/- 9 vs. 271 +/- 18 pmol/mg of protein). Scatchard analysis of saturation binding data revealed two slopes, a result suggesting at least two binding populations. This binding was inhibited by GTP and its analog but not by 5'-adenylylimidodiphosphate [App(NH)p], GMP, or UTP. Following sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis (PAGE) of myelin proteins and blotting on nitrocellulose, [alpha-32P]GTP bound to three bands in the 21-27-kDa range in a manner inhibited by GTP and GTP gamma S but not App(NH)p. ADP-ribosylation of myelin with [32P]NAD+ and cholera toxin labeled a protein of 43 kDa, whereas reaction with pertussis toxin labeled two components of 40 kDa. Cholate extract of myelin subjected to chromatography on a column of phenyl-Sepharose gave at least three major peaks of [35S]GTP gamma S binding activity. SDS-PAGE and immunoblot analyses of peak I indicated the presence of Go alpha, Gi alpha, and Gs alpha. Further fractionation of peak II by diethyl-aminoethyl-Sephacel chromatography gave one [35S]GTP gamma S binding peak with the low-molecular-mass (21-27 kDa) proteins and a second showing two major protein bands of 36 and 40 kDa on SDS-PAGE.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Detection of G proteins in purified bovine brain myelin. 190 10


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