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)

In the human erythroleukemia cell line, HEL, prostaglandin E2 (PGE2) and the stable prostacyclin analogue, iloprost, increase cytosolic Ca2+ concentration ([Ca2+]i) via pertussis toxin-sensitive and -insensitive pathways. Unlike iloprost, the stable prostacyclin analogue cicaprost (ZK 96480), is devoid of agonistic properties at prostaglandin E2 receptors. We compared the effects of cicaprost, iloprost and PGE2 on [Ca2+]i in HEL cells. Cicaprost, iloprost and PGE2 were similarly potent to increase [Ca2+]i in HEL cells. However, unlike the effects of PGE2, those of the prostacyclin analogues were not inhibited by pertussis toxin. The prostaglandins studied increased [Ca2+]i through both mobilization from internal stores and Ca2+ influx from the extracellular space. Prostacyclin analogue- and PGE2-induced rises in [Ca2+]i were desensitized in a homologous manner. Additionally, there was cross-desensitization between cicaprost and iloprost, but not between the prostacyclin analogues and PGE2. Our data suggest that in HEL cells (i) cicaprost and iloprost act through prostacyclin receptors and (ii) that these receptors couple to pertussis toxin-insensitive heterotrimeric regulatory guanine nucleotide-binding proteins, (iii) resulting in an increase in [Ca2+]i by Ca2+ mobilization from internal stores and sustained influx.
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PMID:The prostacyclin analogues, cicaprost and iloprost, increase cytosolic Ca2+ concentration in the human erythroleukemia cell line, HEL, via pertussis toxin-insensitive G-proteins. 128 Apr 55

The relationship between calcium mobilization and phospholipase D (PLD) activation in response to E-series prostaglandins (PGEs) was investigated in human erythroleukemia cells. Intracellular free Ca2+ concentration ([Ca2+]i) was increased by PGE1 and PGE2 over the same concentration range at which PLD activation was seen. Pretreatment of cells with pertussis toxin greatly inhibited the PGE-stimulated increase in [Ca2+]i, implying that a G protein participates in the PGE receptor signaling process. The peak level and also the plateau level of Ca2+ mobilization stimulated by these prostaglandins were markedly decreased in Ca(2+)-depleted medium, indicating that both extracellular and intracellular Ca2+ stores contribute to the changes in [Ca2+]i. Likewise, activation of PLD by PGE1 and PGE2 was abolished by pertussis toxin pretreatment or incubation in Ca(2+)-depleted medium. U73122, a putative phospholipase C inhibitor, blocked both Ca2+ mobilization and PLD activation in PGE-stimulated cells. Furthermore, the intracellular loading of BAPTA, a Ca2+ chelator, inhibited both Ca2+ mobilization and PLD activation by PGE1 and PGE2 in a similar dose-dependent manner. Simultaneous measurement of [Ca2+]i and PLD activity in the same cell samples indicated that PLD activity increases as a function of [Ca2+]i in a similar fashion in cells stimulated either by PGEs or by the calcium ionophore ionomycin. Taken together, these findings suggest that a rise in [Ca2+]i is necessary for PGE-stimulated PLD activity in human erythroleukemia cells.
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PMID:Direct relationship between intracellular calcium mobilization and phospholipase D activation in prostaglandin E-stimulated human erythroleukemia cells. 131 95

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

Phospholipase D (PLD) can be activated by a variety of receptor agonists in different cell types. However, an effect of prostaglandins (PGs) on the activity of this enzyme has not been demonstrated previously. In this study, we found that PGE1 could stimulate PLD in human erythroleukemia cells, as measured by phosphatidylethanol formation, with an ED50 of 3.5 x 10(-7) M. PGE2 was also active, but other PGs including prostacyclin, PGD2 and PGF2, had no effect. PGE1 also elicited cyclic AMP production over the same concentration range that activated PLD. However, it is unlikely that cyclic AMP per se is responsible for PGE-induced PLD activation, because PLD could be substantially activated by PGE2 at concentrations (0.1-1 microM) which did not stimulate cyclic AMP production. Furthermore, no increase of phosphatidylethanol formation could be observed when cells were treated with other adenylyl cyclase-activating agents such as prostacyclin, forskolin and vasoactive intestinal peptide. In Ca+(+)-free medium, PLD activation by PGE1 and PGE2 was greatly reduced, indicating that their effect was through a Ca+(+)-dependent pathway. Pretreatment of cells with pertussis toxin abolished PGE1- and PGE2-stimulated PLD activity, implying the involvement of a G protein in the PGE-mediated signal transduction pathway. Our results not only indicate that E-series PGs may initiate some of their cellular effects through a novel pathway, activation of PLD, but also suggest that PGE-stimulated PLD activity in human erythroleukemia cells is Ca+(+)-dependent and is regulated via a pertussis toxin-sensitive G protein.
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PMID:Activation of phospholipase D by E-series prostaglandins in human erythroleukemia cells. 165 Aug 37

Guanine nucleotide-binding regulatory proteins, or G proteins, mediate the interaction of agonist receptors on the platelet surface with phospholipase C and adenylyl cyclase. To better understand this process, we have used several approaches to identify which G proteins are present in platelets, normal human megakaryocytes, and human erythroleukemia (HEL) cells, a leukemic cell line with megakaryocytic features. Because platelet and HEL cell responses to thrombin are inhibited by pertussis toxin, we have focused upon the members of the Gi family, whose alpha subunits can be ADP-ribosylated by that toxin. Western blots with antisera specific for Gi alpha demonstrated the presence in both platelets and HEL cells of the three best-described forms of this protein: Gi alpha 1, Gi alpha 2, and Gi alpha 3. Based upon immunoprecipitation studies with [35S]-methionine-labeled HEL cells, their relative abundance appears to be Gi alpha 2 much greater than Gi alpha 3 greater than Gi alpha 1. A HEL cell cDNA library screened with the Gi alpha antisera produced clones encoding Gi alpha 2 and Gi alpha 3 that had sequences similar to those reported from other sources. Gi alpha-specific probes created from these cDNA clones confirmed the presence of mRNA encoding Gi alpha 2 and Gi alpha 3 in both platelets (by Northern blotting) and megakaryocytes (by in situ hybridization). Thus the pertussis toxin substrates that have previously been detected in platelets and HEL cells are shown to be members of the Gi alpha family, all of which are candidates for interaction with receptors for thrombin and other agonists.
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PMID:Identification of the pertussis toxin-sensitive G proteins in platelets, megakaryocytes, and human erythroleukemia cells. 211 27

Human erythroleukemia cells are a model system for studies of alpha 2-adrenergic receptors and their coupling to inhibition of adenylate cyclase (McKernan, R. M., Howard, M. J., Motulsky, H. J., and Insel, P. A. (1987) Mol. Pharmacol. 32, 258-265). Using Fura-2, we show that alpha 2-adrenergic receptor stimulation also increases intracellular Ca2+ in these cells by 80-250 nM. Although epinephrine only inhibited forskolin-stimulated cAMP generation when beta-adrenergic receptors were blocked, the Ca2+ increase was not affected by beta-adrenergic receptor blockade. The Ca2+ increase was not affected by forskolin or 8-bromo-cAMP. Thus, alpha 2-adrenergic receptors independently couple to elevation of intracellular Ca2+ and adenylate cyclase inhibition. Chelating all extracellular Ca2+ did not reduce the response, demonstrating mobilization of intracellular, rather than influx of extracellular Ca2+. The epinephrine-stimulated Ca2+ mobilization occurred prior to any detectable increase in inositol-(1,4,5)-trisphosphate. It was abolished by pretreatment with pertussis toxin (which blocks some G protein-mediated processes), but not by aspirin and indomethacin (which inhibit cyclooxygenase), nordihydroguaiaretic acid (which inhibits lipoxygenase), or Na+-free buffer (to block any Na+H+ exchange). We conclude, therefore, that alpha 2-adrenergic receptors on human erythroleukemia cells couple to mobilization of intracellular Ca2+ via a (pertussis toxin-sensitive) G protein-mediated mechanism that is independent of inhibition of adenylate cyclase.
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PMID:Alpha 2-adrenergic receptor stimulation mobilizes intracellular Ca2+ in human erythroleukemia cells. 256 96

We have identified alpha 2-adrenergic receptors on human erythroleukemia (HEL) cells, a suspension-grown cell line related to human platelets. properties of receptors were assessed in intact cells by binding of the antagonist [3H]yohimbine and by inhibition of cAMP accumulation. [3H]Yohimbine labeled 5900 +/- 2100 receptors/cell with a Kd of 3.6 +/- 0.9 nM (n = 7). alpha 2-Adrenergic receptors were potently coupled to inhibition of adenylate cyclase, with EC50 values for epinephrine, UK-14,304, and p-aminoclonidine in the low nM range. Treatment of cells with pertussis toxin abolished this response. In radioligand binding studies with membrane preparations [3H]yohimbine and [3H]UK-14,304 bound to the same number of sites (71 versus 69 fmol/mg of protein), and epinephrine competed for [3H]yohimbine binding in a biphasic manner. After addition of GTP, no high affinity [3H]UK-14,304 binding was detected, and epinephrine competed for [3H]yohimbine binding with lower affinity at both 4 degrees and 37 degrees. In studies with intact cells, we detected no specific binding of [3H]UK-14,304 at either 37 degrees or 4 degrees. At 37 degrees, epinephrine competed for all [3H]yohimbine binding sites with a low apparent affinity (Ki = 21 microM), whereas at 4 degrees epinephrine (up to 1 mM) was able to compete for only 59 +/- 13% of [3H]yohimbine-binding sites. The potency of epinephrine in competing for [3H]yohimbine sites in intact cells at 4 degrees was greater than at 37 degrees (Ki = 1 microM) and was similar to that observed with membranes in the presence of GTP. We hypothesize that sites not detectable by epinephrine at 4 degrees are sequestered within the cell. Treatment of HEL cells with pertussis toxin reduced the proportion of receptors on the surface from 51 +/- 12% to 23 +/- 7% (n = 3, p less than 0.05) of the total sites. Treatment of HEL cells with epinephrine (100 microM, 1 hr) reduced the cell surface component to 25 +/- 8% (n = 3) of the total sites. This treatment was not accompanied by significant desensitization of the ability of epinephrine to inhibit cAMP accumulation. We conclude that alpha 2-adrenergic receptors exist in more than one compartment in HEL cells and that interaction of receptors with a guanine nucleotide-binding protein or with agonist may regulate this compartmentation. These cells provide a new model system for the study of expression and metabolism of alpha 2-adrenergic receptors.
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PMID:Compartmentation of alpha 2-adrenergic receptors in human erythroleukemia (HEL) cells. 303 40

Neuropeptide Y (NPY), a peptide often coreleased with catecholamines, appears to be an important component of the sympathetic nervous system, but little is known about the molecular basis of its action. We introduce here human erythroleukemia (HEL) cells as a new model system for studies of NPY action. NPY inhibited adenosine 3,5'-cyclic monophosphate (cAMP) accumulation in HEL cells with a 50% effective concentration (EC50) of 3 nM. Additionally NPY increased intracellular Ca2+, as assessed by fura-2 fluorescence, with a similar EC50. Pretreatment with pertussis toxin blocked both responses, suggesting the involvement of one or more G proteins. Chelating extracellular Ca2+ with EGTA did not reduce the Ca2+ signal, demonstrating mobilization from intracellular stores rather than influx. Experiments with various agents demonstrated that the Ca2+ mobilization was not secondary to lowering of cAMP levels, formation of arachidonic acid products, or Na+-H+ exchange. Ca2+ mobilization also did not appear to be associated with inositol phosphate generation. In conclusion, we demonstrate for the first time that NPY, in addition to inhibiting adenylate cyclase, also can elevate intracellular Ca2+. HEL cells should prove useful in further studies of the molecular basis of NPY action.
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PMID:Neuropeptide Y mobilizes Ca2+ and inhibits adenylate cyclase in human erythroleukemia cells. 320 64

Urea extracts of B. pertussis, but not B. bronchiseptica, cause large and sustained intracellular cAMP elevation in several neoplastic cell lines. These cAMP elevations are associated with growth inhibition (HL-60, Friend erythroleukemia) and a phenotypic change/differentiation (HL-60, L1210). B. pertussis extract injections prolong survival of L1210 tumor-bearing mice. Pretreatment of L1210 cells with B. pertussis extract both delays mortality and induces growth of solid tumors instead of ascites in subsequently inoculated mice. We conclude that B. pertussis adenylate cyclase is capable of invading a variety of neoplastic cells to catalyze the intracellular formation of large amounts of cAMP. These cAMP elevations are durable and promote growth arrest, differentiation, or phenotypic alterations reflected in altered biologic behavior. B. pertussis adenylate cyclase should prove to be a useful tool for manipulating cAMP levels in neoplastic cells to elucidate the role of cAMP in malignant transformation.
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PMID:Antineoplastic effects of Bordetella pertussis adenylate cyclase. 609 16

Receptor-induced binding of the stable GTP analogue, guanosine 5'-[gamma-thio]triphosphate (GTP [gamma S]), to guanine nucleotide-binding regulatory proteins (G proteins) was measured in various permeabilized cells. In myeloid differentiated human leukemia (HL-60) cells, permeabilized with either digitonin, streptolysin O or Staphylococcus aureus alpha-toxin, binding of GTP[gamma S] induced by three distinct chemoattractant receptors was observed. The extent of receptor-stimulated GTP[gamma S] binding (maximally about 2-fold) was independent of the type of permeabilizing agent used. In human erythroleukemia cells permeabilized with digitonin, agonist activation of thrombin and neuropeptide Y receptors increased GTP[gamma S] binding by 1.8- and 1.5-fold, respectively. Finally, in adherently grown human embryonic kidney cells permeabilized with digitonin, activation of the stably expressed human muscarinic m3 receptor increased GTP[gamma S] binding by about 1.6-fold. In digitonin-permeabilized HL-60 cells, a quantitative analysis of formyl peptide receptors and interacting G proteins was performed. About 50,000 formyl peptide receptors per cell were detected. Agonist binding to these receptors was fully sensitive to regulation by guanine nucleotides and pertussis toxin. The number of high-affinity GTP[gamma S] binding sites, most likely representing heterotrimeric G proteins, was calculated to be about 670,000 per cell. Stimulation of formyl peptide receptors led to the activation of about 130,000 of high-affinity GTP[gamma S] binding sites, indicating a ratio of about three activated G proteins per one agonist-activated receptor.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Analysis of receptor-G protein interactions in permeabilized cells. 763 Apr 24


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