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 regulation of cellular responsiveness to dopamine via the D2 dopamine receptor was investigated in mouse fibroblast Ltk-cells stably expressing the rat D2-short receptor [Nature (Lond.) 336:783-787 (1988)]. Dopamine inhibited forskolin-stimulated cAMP levels in these cells (half-maximal inhibition at 3.9 +/- 1.1 nM), and the inhibition by dopamine was blocked by D2 antagonists and was pertussis toxin sensitive. Treatment of these cells with the D2 agonist quinpirole (1 microM) resulted in desensitization of dopaminergic inhibition of forskolin-stimulated cAMP accumulation, with a approximately 4-fold decrease in the potency of dopamine after 1 hr of treatment. No significant changes in total cellular D2 receptor concentrations were observed, even after prolonged agonist treatment. At longer time points, basal and forskolin-stimulated cellular cAMP levels were increased in treated cells. The effect of D2 agonist treatment on membrane adenylyl cyclase (EC 4.6.1.1) activity was examined. Basal and forskolin- and prostaglandin E1-stimulated adenylyl cyclase activities were increased by quinpirole treatment for 24 hr. This sensitization of adenylyl cyclase was blocked by the presence of a D2 antagonist. Pertussis toxin pretreatment blocked the sensitization of adenylyl cyclase by quinpirole, although pertussis toxin also caused increased adenylyl cyclase activity on its own. Sensitization was not dependent upon dopaminergic inhibition of intracellular cAMP levels, because quinpirole treatment in the presence of membrane-permeable cAMP analogs or 3-isobutyl-1-methylxanthine (an inhibitor of cAMP phosphodiesterase) resulted in greater sensitization of adenylyl cyclase activity than quinpirole treatment alone. These results suggest that, in this model system, responsiveness to dopamine via the D2 receptor is regulated by both desensitization of receptor function and sensitization of the stimulatory adenylyl cyclase pathway.
Mol Pharmacol 1991 Jan
PMID:Regulation of responsiveness at D2 dopamine receptors by receptor desensitization and adenylyl cyclase sensitization. 184 20

The effect of alpha 2-adrenergic receptor activation on adenylate cyclase activity in Chinese hamster ovary cells stably transfected with the alpha 2A-adrenergic receptor gene is biphasic. At lower concentrations of epinephrine forskolin-stimulated cyclic AMP production is inhibited, but at higher concentrations the inhibition is reversed. Both of these effects are blocked by the alpha 2 antagonist yohimbine but not by the alpha 1 antagonist prazosin. Pretreatment with pertussis toxin attenuates inhibition at lower concentrations of epinephrine and greatly potentiates forskolin-stimulated cyclic AMP production at higher concentrations of epinephrine. alpha 2-Adrenergic receptor stimulation also causes arachidonic acid mobilization, presumably via phospholipase A2. This effect is blocked by yohimbine, quinacrine, removal of extracellular Ca2+, and pretreatment with pertussis toxin. Quinacrine and removal of extracellular Ca2+, in contrast, have no effect on the enhanced forskolin-stimulated cyclic AMP production. Thus, it appears that the alpha 2-adrenergic receptor in these cells can simultaneously activate distinct signal transduction systems; inhibition of adenylate cyclase and stimulation of phospholipase A2, both via G1, and potentiation of cyclic AMP production by a different (pertussis toxin-insensitive) mechanism.
Mol Pharmacol 1991 Feb
PMID:Alpha 2-adrenergic receptor stimulation of phospholipase A2 and of adenylate cyclase in transfected Chinese hamster ovary cells is mediated by different mechanisms. 184 97

A rat D2L dopamine receptor, a splice variant of the D2 receptor, has recently been cloned. When transfected into and stably expressed in Chinese hamster ovary cells, these receptors mediate the inhibition of both basal and forskolin-stimulated cAMP production, as previously described. We examined what role this receptor might play in the production of the second messenger arachidonic acid. The calcium ionophore A23187 stimulated the release of arachidonic acid, and this release of arachidonic acid was potentiated by dopamine in a concentration-dependent manner. Dopamine alone, however, had no effect on arachidonic acid release. Quinpirole, a D2-selective agonist, augmented A23187-stimulated arachidonic acid release, and sulpiride, a D2-selective antagonist, blocked this augmentation. cAMP analogs and agents that activate adenylyl cyclase were utilized in an attempt to overcome this dopamine effect. Forskolin, prostaglandin E2, dibutyryl-cAMP, 8-(4-chlorophenylthio)-cAMP, and pertussis toxin all had no appreciable effect on either A23187-stimulated arachidonic acid release or the dopamine enhancement. Inhibition of protein kinase C using long term phorbol ester desensitization and pharmacological inhibitors diminished the dopamine potentiation of arachidonic acid release. These results suggest that the D2 receptor may be increasing the release of arachidonic acid by a mechanism involving protein kinase C but independent of the D2 receptor's inhibition of adenylyl cyclase.
Mol Pharmacol 1991 Mar
PMID:Transfected D2 dopamine receptors mediate the potentiation of arachidonic acid release in Chinese hamster ovary cells. 184 57

ESA152 is a highly hydrophobic 18 kDa sialoglycoprotein, which becomes expressed on ram sperm in the proximal cauda epididymis. ESA 152 is expressed on all regions of the sperm surface, most strongly on the posterior region of the head, most weakly on the anterior region of the head. In this paper, we show that induction of the acrosome reaction with Ca2+ ionophore causes ESA152 to be redistributed from the posterior to the anterior region of the head plasma membrane. Cross-linking ESA152 with bivalent antibody causes similar redistribution and induces the acrosome reaction. Induction of the acrosome reaction with ESA152 antibody requires Ca2+ but is insensitive to (10 ng/ml) pertussis toxin.
Mol Reprod Dev 1991 Jun
PMID:Cross-linking a maturation-dependent ram sperm plasma membrane antigen induces the acrosome reaction. 187 27

The signal transduction mechanisms involved in complement fragment C5a-induced recruitment of actin to the cytoskeleton have been investigated using U-937 cells differentiated by exposure to dibutyryl cyclic AMP. Two parameters of cytoskeletal activation were compared: F-actin formation and nucleation of polymerization of pyrenyl-actin in whole cell lysates. The dose dependency of these responses to C5a was clearly different to that observed for [3H]inositol phosphate formation and also markedly different from that observed for the production of reactive oxygen intermediates (ROI). Further evidence to dissociate inositol lipid hydrolysis from these cytoskeletal responses was obtained by treating cells with neomycin, phorbol myristate acetate and pertussis toxin and by modulating the levels of intracellular Ca2+ using quin 2. Inhibition of [3H]inositol phosphate and ROI production was not correlated with effects on actin recruitment or nucleation. In addition, these agents had differing effects on F-actin formation and nucleation activity. The results show that the production of inositol phosphates is not required for stimulating either F-actin formation or nucleation activity and also that ligand-induced polymerization of actin depends primarily upon an increase in the availability of G-actin rather than nucleation sites. These cytoskeletal responses are apparently controlled by different signalling pathways which diverge at an early stage.
J Mol Endocrinol 1991 Jun
PMID:Evidence for the involvement of multiple signalling pathways in C5a-induced actin polymerization and nucleation in human monocyte-like cells. 188 86

Five ADP-ribosylating bacterial toxins, pertussis toxin, cholera toxin, diphtheria toxin, Escherichia LT toxin and Pseudomonas exotoxin A, show significant homology in selected segments of their sequence. Site-directed mutagenesis and chemical modification of residues within these regions cause loss of catalytic activity and of NAD binding. On the basis of these results and of molecular modelling based on the three-dimensional structure of exotoxin A, the geometry of an NAD binding site common to all the toxins is deduced and described in the paper. For diphtheria toxin, sequence similarity with exotoxin A is such that its preliminary structure can be computed by molecular modelling, whereas for the other toxins similarity appears to be restricted to the NAD binding site. Moreover, an analysis of molecular fitting of the NAD molecule into its binding cavity suggests a new model for the conformation of the bound NAD that better accounts for all available experimental information.
Mol Microbiol 1991 Jan
PMID:Computer modelling of the NAD binding site of ADP-ribosylating toxins: active-site structure and mechanism of NAD binding. 190 17

Triethyl lead chloride (Et3PbCl) was found to induce a shift of fatty acids from membrane phospholipids to triacylglycerols in the human promyelocytic leukemia cell line HL-60. High concentrations of Et3PbCl (greater than 10 microM) caused a substantial liberation of [14C]arachidonic acid within 10 to 20 min in dimethyl sulfoxide-differentiated cells, comparable to the effect of the calcium ionophore A23187 (10 microM). Following liberation of arachidonic acid, its metabolites could be detected. Prolongation of the incubation time and reduction of Et3PbCl concentration resulted in a shift of fatty acids from phospholipids to triacylglycerols. Deacylation of phospholipids and reacylation into phospholipids and triacylglycerols were in equilibrium when the cells were treated with Et3PbCl at concentrations of less than or equal to 10 microM for 5 hr or less than or equal to 1 microM for 24 hr; no increase of free fatty acids could be observed, and the loss of fatty acids within the phospholipids was equivalent to the increase of fatty acid content within the triacylglycerols. Moreover, under these conditions, no loss of viability was seen after 24 hr, as compared with untreated differentiated cells. This concentration- and time-dependent effect of Et3PbCl might be due to a stimulated liberation of fatty acids via phospholipase A2, because this stimulation could be totally prevented by the phospholipase inhibitors quinacrine and p-bromophenacylbromide. Additionally, pretreatment of differentiated HL-60 cells with pertussis toxin resulted in a drastic reduction of [14C]arachidonic acid liberation when cells were stimulated with Et3PbCl. These results suggest the involvement of a pertussis toxin-sensitive GTP-binding protein and of a signal transduction mechanism during stimulated fatty acid release; release does not seem to be via a direct stimulation of phospholipase activity by the lead compound.
Mol Pharmacol 1991 Apr
PMID:Directed shift of fatty acids from phospholipids to triacylglycerols in HL-60 cells induced by nanomolar concentrations of triethyl lead chloride: involvement of a pertussis toxin-sensitive pathway. 190 39

Angiotensin II can inhibit hormone-stimulated adenylyl cyclase in intact hepatocytes or in hepatic membrane preparations. Because the response can be blocked by pertussis toxin, the object of the present study was to determine which of the known variants of Gi can couple angiotensin II receptors to inhibition of adenylyl cyclase. The potential candidates were identified by probing RNA isolated from rat hepatocytes with cDNAs specific for the alpha subunits of known toxin-sensitive guanine nucleotide-binding regulatory proteins (G proteins). Hepatocytes contained no detectable RNA for the Go or Gi1 alpha subunits and similar levels of RNA coding for the Gi2 and Gi3 alpha subunits. To determine whether Gi3 could couple angiotensin receptors to inhibition of cyclase, membranes were prepared from hepatocytes whose G proteins were fully ADP-ribosylated with pertussis toxin, and the Gi3 holoprotein purified from rabbit liver was reconstituted into the membranes. The nature of the Gi3 reconstituted into the membrane was assessed by immunoblotting with antibodies specific for the Gi alpha subunits. Reconstitution of 6-10 pmol of Gi3/mg of membrane protein into the toxin-treated membranes restored the ability of 10 nM angiotensin II to inhibit adenylyl cyclase. Because pertussis toxin has nonspecific effects, an assay was developed to measure the interaction of the angiotensin receptor with reconstituted G proteins in normal membranes. In the presence of Mg2+, guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S) caused a reduction of the affinity of the angiotensin II receptor for 125I-angiotensin II that was stable to washing and the detergents used to reconstitute G proteins into the membranes. Using this protocol to activate G proteins and "uncouple" receptors, the ability of the GDP-liganded form of Gi to restore high affinity binding was examined. Reconstitution of about 10-15 pmol of oligomeric Gi3/mg of membrane protein restored both the high affinity state of the angiotensin II receptor and the ability of GTP gamma S to shift the affinity to a lower state. The same shift in receptor affinity could be accomplished by reconstituting the Gi3 alpha subunit, resolved free of beta gamma subunits, into the membranes. Reconstitution of up to 50 pmol of Gs/mg of membrane protein had no effect on angiotensin II receptor affinity. The results suggest that a major form of Gi in hepatocytes is Gi3 and that it can couple angiotensin receptors to inhibition of adenylyl cyclase.
Mol Pharmacol 1991 Aug
PMID:Inhibitory GTP-binding regulatory protein Gi3 can couple angiotensin II receptors to inhibition of adenylyl cyclase in hepatocytes. 190 48

Alveolar macrophages (AM) migrate less well in response to chemotactic ligands than do monocytes and neutrophils. The response of monocytes and neutrophils to chemotactic ligands is mediated at least in part by pertussis toxin-sensitive guanine nucleotide binding proteins (Gi proteins). Whether this is also true in AM is uncertain. We hypothesized that decreased chemotaxis by AM was due in part to diminished Gi protein and/or chemotactic receptor density in AM. G proteins are heterotrimers made up of alpha, beta, and gamma subunits; the predominant pertussis toxin-sensitive Gi proteins are those containing alpha i2 or alpha i3 subunits. Pertussis toxin pretreatment (0.5 microgram/ml) significantly reduced AM, monocyte, and neutrophil chemotaxis to N-formyl-L-methionyl-L-leucyl-L-phenylalanine (FMLP) and human zymosan-activated serum (P less than 0.05). However, as previously noted, AM chemotaxis was much less than that observed in monocytes and neutrophils. Immunoblots using antibodies that are specific for alpha i2 and alpha i3 showed that AM contained approximately 3-fold less alpha i2 and approximately 10-fold less alpha i3 per microgram of plasma membrane protein than did monocytes or neutrophils. Similar results were obtained in immunoblots made using antibodies to common alpha subunit determinants and to the beta 36 subunit. A comparable approximately 4-fold reduction in density of receptors for [3H]FMLP was found in AM compared to neutrophils. The diminished density of Gi proteins and FMLP receptors was not due to a generally decreased density of plasma membrane proteins in AM, since the density of the membrane-associated tyrosine kinase hck was similar in AM, monocytes, and neutrophils.(ABSTRACT TRUNCATED AT 250 WORDS)
Am J Respir Cell Mol Biol 1991 Jul
PMID:Signal transduction in human alveolar macrophages: diminished chemotactic response to FMLP correlates with a diminished density of Gi proteins and FMLP receptors. 190 89

We have investigated the possible role of guanine nucleotide-binding proteins in the process of antigen-induced exocytosis in a cultured rat mast cell line, RBL-2H3 cells. The mRNAs for the alpha subunits of the guanine nucleotide-binding proteins G alpha S (short and long forms), G alpha i-2, G alpha i-3, and G alpha Z were detected by hybridization with G alpha-specific oligonucleotide probes. The corresponding proteins were identified in membranes of RBL-2H3 cells on the basis of size, immunoreactivity with specific antibodies, and their ability to serve as substrates for ADP-ribosylation by cholera toxin or pertussis toxin. Treatment of cells with as little as 10(-9) to 10(-7) M dexamethasone markedly decreased the amount of G alpha Z mRNA and membrane G alpha Z, as well as the responsiveness of the cells to antigen stimulation. In the same cells, the exposure to dexamethasone caused an increase in the amounts of certain other G alpha subunits, particularly G alpha i-3, and in the responsiveness of the cells to an adenosine analog, N(ethylcarboxamido)-adenosine. Because of the apparent decrease in G alpha Z mRNA and protein in dexamethasone-treated cells and the fact that neither cholera toxin nor pertussis toxin inhibits the stimulatory signals to antigen [J. Biol. Chem. 265:745-753 (1990)], we suggest that G alpha Z is a potential candidate for regulating the early signals in antigen-stimulated RBL-2H3 cells.
Mol Pharmacol 1991 Oct
PMID:GTP-binding protein G alpha Z: its down-regulation by dexamethasone and its credentials as a mediator of antigen-induced responses in RBL-2H3 cells. 192 83


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