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 expression of subunits of the guanine nucleotide regulatory protein that mediates hormonal stimulation of adenylyl cyclase (Gs) and of the guanine nucleotide regulatory protein that mediates hormonal inhibition of adenylyl cyclase (Gi) was studied during cell migration and differentiation in the rat small intestine crypt-villus axis. Proliferative crypt cells were separated from nonproliferative mature villus cells and the following data were obtained: 1) alpha s subunits were more abundant in crypt cells than in villus cells as evidenced by cholera toxin-catalyzed [32P]NAD ribosylation and Western blotting of this relative molecular weight (M(r)) 42,000 protein; 2) alpha i2- and alpha i3-subunits (M(r) 40,000 and M(r) 41,000, respectively) were preferentially expressed in villus cells as evidenced by pertussis toxin-catalyzed [32P]NAD ribosylation and Western blotting (alpha i1-subunit was not detectable in intestinal epithelium by using these techniques); 3) Western blotting showed a higher expression of the common beta- (M(r) 36,000) subunit of G proteins in villus cells than in crypt cells; and 4) Northern blot analysis using an alpha s-subunit oligonucleotide probe showed a 1.9-kb mRNA that was more abundant in crypt cells than in villus cells. In contrast, alpha i2- and alpha i3-mRNA species (2.3 and 3.5 kb, respectively), analyzed by using specific cDNA probes, were much more abundant in villus cells than in crypt cells. Finally, two beta-subunit mRNA species of 3.3 and 1.8 kb were detectable in intestinal epithelial cells and were more abundant in villus cells than in crypt cells.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Gs and Gi protein subunits during cell differentiation in intestinal crypt-villus axis: regulation at the mRNA level. 137 46

Fully-differentiated mouse 3T3-L1 fibroblasts accumulate large amounts of lipid at 7-10 days after induction by insulin or by dexamethasone and a methyl xanthine. G proteins mediate transmembrane signalling from a diverse group of cell-surface receptors to effector units that include phospholipase C, adenylyl cyclase and ion channels. They are also targets of regulation themselves. 3T3-L1 fibroblasts display marked changes in levels of G protein when induced to differentiate to adipocytes. Here we show that cholera toxin, which ADP-ribosylates and activates the G protein subunit Gs alpha, blocks the induction of differentiation, whereas increasing intracellular cyclic AMP directly with the dibutyryl analogue or indirectly with pertussis toxin or forskolin does not affect differentiation. Oligodeoxynucleotides antisense to the sequence encoding Gs alpha accelerate differentiation markedly. The time course of adipogenesis declined from 7-10 days in controls to roughly 3 days in cultures treated with antisense-Gs alpha oligodeoxynucleotides, whereas oligodeoxynucleotides, antisense to Gi alpha 1, Gi alpha 3, and sense and missense to Gs alpha, had no such effect. Antisense-Gs alpha alone induced differentiation by day 7, indicating that Gs alpha activity modulates differentiation in 3T3-L1 cells, acting in a new role which is independent of increased intracellular cAMP.
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PMID:Antisense oligodeoxynucleotides to GS protein alpha-subunit sequence accelerate differentiation of fibroblasts to adipocytes. 137 45

Bordetella pertussis produces a calmodulin-stimulated adenylyl cyclase that invades animal cells and raises intracellular cAMP levels [Confer, D. L., & Eaton, J. W. (1982) Science 217, 948-950; Shattuck, R. L., & Storm, D. R. (1985) Biochemistry 24, 6323-6328]. The mechanism for invasion of animal cells by this enzyme has not been defined, but there is considerable evidence that it does not enter by receptor-mediated endocytosis [Gordon, V. M., Leppla, S. H., & Hewlett, E. L. (1988) Infect. Immun. 56, 1066-1069; Donovan, M. G., & Storm, D. R. (1990) J. Cell. Physiol. 145, 444-449]. In this study, the importance of high-affinity calmodulin (CaM) binding for entry of the enzyme into neuroblastoma cells was evaluated using a mutant enzyme that has significantly lower affinity for calmodulin than the wild-type enzyme. Oligonucleotide-directed site-specific mutagenesis was used to create a point mutant at a critical tryptophan residue (Trp-242) within the proposed CaM binding domain of the B. pertussis adenylyl cyclase. Substitution of Trp-242 with Glu lowered the apparent affinity of the enzyme for calmodulin by 250-fold; however, the maximal enzyme activity in the presence of saturating calmodulin was equivalent to the wild-type enzyme. The Glu-242 mutant adenylyl cyclase was returned to B. pertussis by homologous recombination, and the enzyme produced by this strain was examined for invasion of neuroblastoma cells. Although the mutant enzyme stimulated the production of intracellular cAMP in neuroblastoma cells, the rate of cAMP accumulation was at least 10-fold lower than that caused by the wild-type enzyme.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:High-affinity calmodulin binding is required for the rapid entry of Bordetella pertussis adenylyl cyclase into neuroblastoma cells. 139 Jun 75

GTP stimulation of adenylyl cyclase from the dimorphic pathogenic fungus Candida albicans is greatly enhanced by preincubation of membrane proteins with cholera toxin, NAD and ATP. In the presence of [32P]NAD the toxin catalyzes the covalent incorporation of radioactivity into a membrane protein of 40 kDa. Pertussis toxin catalyzes the transference of the radioactivity from [32P]NAD to a 32 kDa protein. Two major proteins of 40-42 and 30-32 kDa can also be recognized in Western blots by an anti G alpha-common antibody. The results support the idea that G proteins are part of the hormone sensory transduction chain of Candida [(1990) Biochem. Biophys. Res. Commun. 167, 1177-1183].
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PMID:Enzymatic and immunological detection of G protein alpha-subunits in the pathogenic fungus Candida albicans. 139 91

Forskolin-resistant mutants derived from Y1 adrenocortical cells display decreased responsiveness both to receptor and postreceptor stimulators of adenylyl cyclase and decreased amounts of the alpha subunits of the GTP-binding proteins (G proteins) that mediate stimulation (Gs) and inhibition (Gi) of adenylyl cyclase--namely, Gs alpha and Gi alpha-2. This phenotype is suggestive of a mutation that affects the processing or plasma membrane incorporation of G protein alpha subunits. Since the membrane attachment of heterotrimeric G proteins has been ascribed in part to the beta gamma subunits, we examined the quantity and functional activity of beta gamma subunits in wild-type Y1 and forskolin-resistant Forsk-10r-9 and Forsk-10r-3 cells. We now show that two assays previously used to examine the activity of purified beta gamma subunits--namely, to support either rhodopsin-catalyzed guanyl nucleotide exchange on Gt alpha or pertussis toxin-catalyzed ADP-ribosylation of Gt alpha--can be used with detergent extracts of cells. In both assays the beta gamma activity in Forsk-10r-9 and Forsk-10r-3 extracts was decreased by 53-76% compared with wild-type Y1 extracts. When normalized for immunoreactive beta subunit, the beta gamma activity in the Forsk-10r-9 samples was decreased by 55-57% compared with the wild-type Y1 samples. These results suggest that a mutation of one of the G protein beta or gamma subunits may result in the multiple defects of adenylyl cyclase activity and apparent loss of G protein alpha subunits seen in the forskolin-resistant mutant cells. The frequency with which these spontaneous mutations arise in the Y1 cell line suggests that they may contribute more generally to genetic abnormalities in signal transduction.
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PMID:Defective guanyl nucleotide-binding protein beta gamma subunits in a forskolin-resistant mutant of the Y1 adrenocortical cell line. 140 89

The regulation of membrane ion channels by guanine nucleotide-binding proteins (G proteins) has been described in numerous tissues. This regulation has been shown to involve the membrane-delimited stimulatory action of G proteins on ion channels. We now show that single calcium-activated potassium channels (KCa channels) in airway smooth muscle cells are both stimulated and inhibited by G proteins in membrane patches. We demonstrate that the beta-adrenergic agonist isoproterenol stimulates channel activity via the alpha subunit of the stimulatory G protein of adenylyl cyclase, Gs, and that channel opening is inhibited by the action of the muscarinic agonist methacholine, acting via a pertussis toxin-sensitive G protein. Isoproterenol stimulated and methacholine inhibited channel activity in the same outside-out patches when GTP was present at the cytosolic surface of the patch. In inside-out patches, addition of GTP and guanosine 5'-[gamma-thio]triphosphate (GTP[gamma S]) augmented channel activity when isoproterenol was included in the patch pipette, and inhibited channel activity when methacholine was included in the pipette. Consistent with these results, in the presence of GTP[gamma S], the alpha subunit of Gs (alpha s.GTP[gamma S] complex) opened KCa channels in a dose-dependent manner, whereas in the presence of guanosine 5'-[beta-thio]diphosphate, alpha s had no effect. By contrast, application of activated alpha i or alpha o proteins did not inhibit channel activity in inside-out patches, indicating that channel inhibition is more complex than a simple alpha subunit/channel interaction, similar to the complex inhibitory regulation of adenylyl cyclase. These results suggest that hormonal regulation of KCa channels shares substantial features with the regulation of adenylyl cyclase and demonstrate that a single ion channel may serve as the regulatory target for the membrane-delimited action of stimulatory and inhibitory G proteins. Moreover, they demonstrate a potentially important functional pathway by which beta-adrenergic and other Gs-linked receptors stimulate relaxation of smooth muscle, independent of cAMP-dependent protein phosphorylation.
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PMID:Stimulatory and inhibitory regulation of calcium-activated potassium channels by guanine nucleotide-binding proteins. 143 13

The signal transduction linkages of the cloned human 5-HT1A receptor as expressed stably in CHO cells were studied. A transfected clonal cell line which expresses 900 +/- 36 fmol 5-HT1A receptor/mg protein (designated CHO-5-HT1A/WT-27) responded to 5-HT and/or 8-OH-DPAT by coupling to several second messenger pathways. The 5-HT1A receptor inhibited, but did not stimulate, membrane adenylyl cyclase activity and whole cell cAMP accumulation in a dose-dependent manner (for 5-HT, IC50 = 146 +/- 27 and 55 +/- 12 nM, respectively). Activation of the receptor was associated with other signal transduction linkages: (i) a 40-50% increase in hydrolysis of inositol phosphates (for 5-HT, EC50 = 1.33 +/- 0.15 microM for 5-HT), (ii) a transient elevation of cytosolic Ca2+ levels (apparent at 1-100 microM 5-HT) which was not affected by chelation of extracellular Ca2+ by EGTA, and (iii) an augmentation of [3H]-arachidonic acid release pharmacologically with the calcium ionophore A23187 or by activation of endogenous thrombin or P2 purinergic receptors (for 5-HT, EC50 = 1.22 +/- 0.17 microM). This pathway may be an amplification mechanism for signaling in anatomic regions with high concentrations of several neuro-transmitters, hormones or autacoids, such as at neuronal junctions or near areas of platelet aggregation. All linkages were sensitive to pertussis toxin pre-treatment (IC50 approximately 0.5-0.6 ng/ml x 4.5 h for all pathways), suggesting the involvement of Gi protein(s) in these signal transduction pathways. Coupling to varied signal transduction pathways in a single cell system may be a common feature of receptors which classically inhibit adenylyl cyclase such as the 5-HT1A receptor.
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PMID:Functional expression of human 5-HT1A receptors and differential coupling to second messengers in CHO cells. 144 78

The purpose of this study was to identify and characterize functional G proteins that couple regulatory peptides with lacrimal secretory functions. Membranes were prepared from isolated rat exorbital lacrimal gland acini, and guanosine 5'-triphosphate (GTP)-dependence of adenylyl cyclase activity, known to be coupled with regulation of secretion, was measured. The guanine nucleotide GTP produced a biphasic response in the activity of membrane-bound adenylyl cyclase during a 10 min incubation with a maximum stimulation at 10(-5) mol/l GTP. Significant inhibition occurred at a dose of 10(-3) mol/l GTP, with cyclic adenosine monophosphate (cAMP) production reduced to less than basal levels. The effect of ADP-ribosylation of membrane proteins by the toxins produced by Vibrio cholera or Bordetella pertussis on lacrimal adenylyl cyclase was assessed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, autoradiography, and laser densitometry. Cholera toxin treatment of membranes resulted in dose-(0.5-100 micrograms/ml) and time-dependent (0-45 min) adenosine diphosphate (ADP)-ribosylation of two membrane proteins with M(r) values of 42,000 and 45,000. Pertussis toxin treatment resulted in the specific ADP-ribosylation of a single protein that migrates with an M(r) value of 41,000. This also was dose (0.5-25 micrograms/ml) and time dependent (0-30 min). Incorporation of 32P into the 45,000 M(r) and 42,000 M(r) proteins in the presence of 50 micrograms/ml cholera toxin was guanine nucleotide dependent, with a two- to threefold increase in labeling when the membranes were incubated with 1 or 0.5 mmol/l GTP. This effect was enhanced in the presence of the nonhydrolyzable GTP analog GTP gamma S.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Guanine nucleotide binding proteins in the dual regulation of lacrimal function. 146 5

The activation of heterotrimeric G proteins results in the exchange of GDP bound to the alpha-subunit for GTP and the subsequent dissociation of a complex of the beta- and gamma-subunits (G beta gamma). The alpha-subunits of different G proteins interact with a variety of effectors, but less is known about the function of the free G beta gamma complex. G beta gamma has been implicated in the activation of a cardiac potassium channel, a retinal phospholipase A2 (ref. 9) and a specific receptor kinase, and in vitro reconstitution experiments indicate that the G beta gamma complex can act with G alpha subunit to modulate the activity of different isoforms of adenylyl cyclase. Of two phospholipase activities that can be separated in extracts of HL-60 cells, purified G beta gamma is found to activate one of them. Here we report that in co-transfection assays G beta gamma subunits specifically activate the beta 2 and not the beta 1 isoform of phospholipase, which acts on phosphatidylinositol. We use transfection assays to show also that receptor-mediated release of G beta gamma from G proteins that are sensitive to pertussis toxin can result in activation of the phospholipase. This effect may be the basis of the pertussis-toxin-sensitive phospholipase C activation seen in some cell systems (reviewed in refs 13 and 14).
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PMID:Subunits beta gamma of heterotrimeric G protein activate beta 2 isoform of phospholipase C. 146 34

In human end-stage heart failure an increased amount of inhibitory G-protein alpha-subunits (Gi alpha) is assumed to play a role in desensitization of the adenylyl cyclase signaling pathway. In the present study, northern blot experiments with 32P-labeled cDNA probes in ventricular tissue samples from explanted human hearts revealed that Gi alpha-2- and Gi alpha-3- mRNA are the predominant Gi alpha-mRNA subtypes in human ventricles, whereas Gi alpha-1-mRNA was not detectable. The mRNA for the stimulatory G-protein alpha-subunit (GS alpha) consisted of two mRNA sizes. Quantification of mRNA levels revealed a 103 +/- 38% increase in Gi alpha-2-mRNA levels in hearts with idiopathic dilative cardiomyopathy (IDC; n = 8), and a 77 +/- 25% increase in hearts with ischemic cardiomyopathy (ICM; n = 6) as compared to nonfailing controls (NF, n = 8). In contrast, Gi alpha-3- and GS alpha-mRNA levels were similar in failing and nonfailing hearts. To investigate whether or not the increased expression of Gi alpha-2-mRNA might be due to chronically elevated catecholamine levels, we determined the influence of a 4-day infusion of isoprenaline (Iso; 2.4 mg/kg.d), propranolol (Prop; 9.9 mg/kg.d), Iso + Prop or 0.9% NaCl as control (Ctr) on myocardial Gi alpha-mRNA and Gi alpha-protein levels in rats. In Iso-treated rats, hybridization experiments revealed a 49 +/- 18% (n = 7) and 27 +/- 7% (n = 8) increase in Gi alpha-2 and Gi alpha-3-mRNA, respectively. Pertussis toxin-catalyzed ADP-ribosylation revealed a 22 +/- 7% (n = 8) increase in Gi-protein as compared to Ctr (n = 8). These alterations were accompanied by an increased potency for the negative inotropic effect (NIE) of carbachol (mean EC50: 0.04 microM vs. 0.28 microM) in the presence of Iso in isolated electrically driven (1 Hz) papillary muscles. Prop itself had no effect, but it antagonized all Iso-induced effects. We conclude that, in human heart failure due to IDC or ICM, increased Gi alpha-2-, but not Gi alpha-3- mRNA levels accompany the increased amount of Gi alpha-protein, suggesting that this increase is at least in part due to increased de novo synthesis. The experiments in rats demonstrated that chronic beta-adrenergic stimulation leads to an increased expression of Gi alpha-mRNA and -protein, and to an enhanced potency of the negative inotropic effect of muscarinic agonists.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Regulation and possible functional implications of G-protein mRNA expression in nonfailing and failing ventricular myocardium. 149 78


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