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)

Pertussis toxin, an irreversible inhibitor of some G proteins, inhibits endothelium-dependent relaxations to certain agonists in porcine coronary arteries. In the present study, the effects of the toxin were examined on endothelium-dependent and -independent relaxations of hypercholesterolemic and atherosclerotic porcine coronary arteries to assess the functional state of the endothelial pertussis toxin-sensitive G protein. Male Yorkshire pigs were maintained on either a regular diet (control group, n = 7) or a 2% high-cholesterol diet (cholesterol-fed group, n = 7) for 10 weeks. After the initial 2 weeks of maintenance, animals in both groups underwent balloon catheter removal of the endothelium of the left anterior descending or left circumflex coronary arteries. Endothelium-dependent responses were examined in vitro after 10 weeks of maintenance; at this time, a full lining of endothelial cells in both left coronary arteries was confirmed histologically. In arteries with endothelium of the control group (normal responses), pertussis toxin significantly inhibited the endothelium-dependent relaxations to serotonin, UK14304 (a selective alpha 2-adrenergic receptor agonist), and thrombin but not those to ADP, bradykinin, or the calcium ionophore A23187. In previously denuded arteries of the control group (effects of endothelial regeneration alone) or intact arteries of the cholesterol-fed group (effects of hypercholesterolemia alone), the relaxations to serotonin, UK14304, and thrombin were impaired significantly; those relaxations were impaired further in previously denuded arteries of the cholesterol-fed group (effects of atherosclerosis). The inhibitory effects of pertussis toxin were significantly reduced after endothelial regeneration and in hypercholesterolemia and were almost absent in atherosclerosis.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Loss of endothelial pertussis toxin-sensitive G protein function in atherosclerotic porcine coronary arteries. 199 83

The regulation of prostacyclin (PGI2) synthesis by cultured human umbilical vein endothelium (HUVEC) was investigated. HUVEC monolayer generation of PGI2 was monitored by RIA of 6-keto PGF1 alpha and dose-dependent increases observed with human alpha- and gamma-thrombins, histamine, or arachidonate. Alpha thrombin (10 nM) produced levels of 6-keto PGF1 alpha approximating responses with 1 microM gamma-thrombin, 5 microM arachidonate, or 10 microM histamine. Diisopropyl phosphorofluoridate-inactivated alpha-thrombin did not stimulate PGI2 release, demonstrating that catalytic activity was required for thrombin-stimulated PGI2 release. Sodium fluoride (NaF), at concentrations known to activate guanine nucleotide regulatory proteins (G proteins), directly stimulated HUVEC PGI2 synthesis in a dose-dependent and time-dependent manner (20 mM NaF, 4.4 +/- 0.5-fold increase at 10 min, 11.9 +/- 1.5-fold increase at 30 min). Neither alpha-thrombin nor NaF-stimulated PGI2 release was dependent upon the availability of extracellular Ca++). The hypothesis that G proteins are involved in agonist-stimulated PGI2 synthesis was further supported by studies using digitonin-permeabilized HUVEC monolayers challenged with another G protein activator, guanosine 5'-0-3-thiotrisphosphate (GTP gamma S), which effected significant dose-dependent increases in PGI2 synthesis compared with control levels of 6-keto PGF1 alpha. In contrast, the G-protein inhibitor GDP beta S, (guanosine 5'-0-2-thiodiphosphate), attenuated alpha-thrombin-mediated prostaglandin generation. Treatment of HUVEC monolayers with pertussis toxin (1 microgram/ml) did not inhibit the PGI2 synthesis stimulated by either alpha-thrombin, NaF, or histamine but catalyzed the ADP ribosylation of a 40 kDa membrane protein which cross-reacted with antisera against a synthetic peptide corresponding to an amino acid sequence common to the alpha-subunit of other G-proteins. Preincubation of HUVEC microsomal membranes with alpha-thrombin diminished pertussis toxin-catalyzed ADP ribosylation in a time-dependent manner. These data suggest that thrombin stimulation of PGI2 synthesis by HUVEC monolayers requires the catalytically functional enzyme and further suggests that the thrombin-occupied receptor is coupled to phospholipase activities by a pertussis toxin-insensitive guanine nucleotide regulatory protein in human endothelial cell membranes.
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PMID:Thrombin-induced prostacyclin biosynthesis in human endothelium: role of guanine nucleotide regulatory proteins in stimulus/coupling responses. 210 25

The cDNA encoding bovine opsin was transfected into Chinese hamster ovary (CHO) cells to generate stable clones expressing the rod cell photoreceptor protein. Cells expressing opsin, when incubated in 11-cis retinal and exposed to light, inhibited forskolin-stimulated adenylyl cyclase activity. Rhodopsin-mediated inhibition of adenylyl cyclase was prevented by treatment of cells with pertussis toxin. In the same cells, thrombin stimulated phosphatidylinositol hydrolysis through G protein-mediated pathways, but rhodopsin neither significantly influenced the action of thrombin nor stimulated phosphatidylinositol hydrolysis. Our findings indicate that rhodopsin selectively regulates a Gi protein in intact CHO cells that is coupled to adenylyl cyclase but not to phospholipase C.
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PMID:Rhodopsin expressed in Chinese hamster ovary cells regulates adenylyl cyclase activity. 210 93

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

Production of the potent lipid autacoid, platelet-activating factor (PAF), is a stimulated response of the endothelium which has important physiologic consequences including mediating adherence of inflammatory cells to the endothelium. Consequently, an understanding of the mechanisms that regulate PAF synthesis by the endothelium is important. To this end, we investigated the role of G proteins as a component of the signal transduction pathway that couples hormonal stimuli to PAF production. The addition of aluminum fluoride (AlF-4) to endothelial cells resulted in production of PAF with a maximal effect at 20 mM fluoride and within 20-60 min of exposure. Alf-4 also augmented the production of PAF which occurs in response to hormonal agonists. In addition, submaximal concentrations of AlF-4 converted an ineffective hormonal agonist (thrombin in bovine cells) to a maximally effective agonist. The adherence of neutrophils to endothelial cells that had been exposed previously to AlF-4 was increased in a manner that paralleled PAF production. PAF production in response to AlF-4 was not consistently affected by pertussis or cholera toxin. Introduction of guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S) into permeabilized endothelial cells also resulted in PAF production, with reversal by guanosine 5'-O-(2-thiodiphosphate) (GDP beta S), consistent with an effect mediated by a G protein. G protein activation with AlF-4 or GTP gamma S resulted in entry of extracellular Ca2+ as determined using 45Ca2+ flux studies and Indo-1 spectrofluorometry. Our data are consistent with the hypothesis that G proteins couple hormone-receptor binding to opening of a membrane calcium channel, a key step in the initiation of PAF production in endothelial cells.
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PMID:Synthesis of platelet-activating factor by endothelial cells. The role of G proteins. 211 26

Noradrenaline (NA) stimulated the release of arachidonic acid (AA) from the [3H]AA-labelled rabbit platelets via alpha 2-adrenergic receptors, since the effect of NA was inhibited by yohimbine. The stimulatory effect of NA in digitonin-permeabilized platelets was completely dependent on the simultaneous presence of GTP and Ca2+. The NA- and thrombin-stimulated releases of AA were markedly decreased by the prior ADP-ribosylation of the permeabilized platelets with pertussis toxin. Antiserum directed against the pig brain Go (a GTP-binding protein of unknown function), recognizing both alpha 39 and beta 35,36 subunits, but not alpha 41, of pig brain, reacted with 41 kDa and 40 kDa bands, with not one of 39 kDa, in rabbit platelet membranes. Anti-Go antiserum inhibited guanosine 5'-[gamma-thio]triphosphate-, A1F4(-)-, NA- and thrombin-stimulated AA releases in the membranes. Although the effect of thrombin was inhibited by low concentrations of anti-Go antiserum, high concentrations of the antiserum was needed for inhibition of the NA effect. Antiserum directed against the pig brain G1 (inhibitory G-protein), recognizing both alpha 41 and beta 35,36 subunits, but not alpha 39, of pig brain, reacted with the 41 kDa band in platelets. Anti-G1 antiserum inhibited only the effect of NA. Reconstitution of the platelet membranes ADP-ribosylated by pertussis toxin with Go, not Gi, purified from pig brain restored the thrombin-stimulated release of AA. In contrast, reconstitution of those membranes with Gi, not Go, restored the NA-stimulated release of AA. These results indicate that different GTP-binding proteins, Gi- and Go-like proteins, may be involved in the mechanism of signal transduction from alpha 2-adrenergic receptors and thrombin receptors to phospholipase A2 in rabbit platelets.
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PMID:Possible involvement of different GTP-binding proteins in noradrenaline- and thrombin-stimulated release of arachidonic acid in rabbit platelets. 211 62

The proto-oncogene c-fos has been implicated in the modulation of various cell functions. We have found that thrombin, a pleiotropic activator of endothelial cells, induced c-fos mRNA in human umbilical vein endothelial cells (HEC). This effect was dose-related (0.05 to 1.0 U/mL) and transient (maximal after 1 hour and negligible within 4 hours). Since thrombin activates phosphoinositide (PI) turnover through a pertussis toxin (PT)-sensitive guanosine triphosphate-binding regulatory protein(s) (G-protein) with subsequent stimulation of protein kinase C (PKC) and Ca2+ movements, we investigated whether these intracellular pathways are also responsible for c-fos induction. PT inhibited thrombin's effect on c-fos expression, but had no effect on c-fos expression by phorbol myristate acetate (PMA). Down regulation of PKC by prolonged exposure to PMA had no effect on thrombin and ionomycin stimulation of c-fos, but inhibited PMA activation of this gene. Quenching of the Ca1(2+) increase in response to quin2 loading in the absence of external Ca2+ suppressed thrombin activity on c-fos transcription. Under the same conditions PMA activity was not inhibited or only partially inhibited. Interleukin-1 beta (IL-1 beta) and basic fibroblast growth factor (bFGF) stimulation of c-fos mRNA level were not inhibited by quin2; on the contrary, ionomycin effect was blocked by this agent. These results indicate that thrombin-induced c-fos expression in HEC does not require a fully active PKC but is dependent on normal intracellular Ca2+ availability.
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PMID:Thrombin induces c-fos expression in cultured human endothelial cells by a Ca2(+)-dependent mechanism. 211 37

G-proteins are transducing proteins that couple a large number of membrane-bound receptors to a variety of intracellular effector systems. Pertussis toxin ADP-ribosylates certain G-proteins causing inhibition of their function. In porcine coronary arteries, pertussis toxin inhibited the endothelium-dependent relaxations evoked by alpha-2-adrenergic or serotonergic receptor stimulation, and by aggregating platelets or thrombin. Relaxations to nitric oxide and endothelium-dependent relaxations to bradykinin, adenosine diphosphate or A23187 were unaffected by the toxin. Therefore, certain endothelium-dependent relaxations are mediated by activation of a pertussis toxin-sensitive G-protein in the endothelial cells, most likely Gi-protein. In porcine coronary arteries with regenerated endothelium (following in vivo denudation), the endothelium-dependent relaxations caused by the pertussis toxin-sensitive stimuli were reduced and were not further affected by pertussis toxin. Relaxations to the other stimuli were not altered by the regeneration process and were still not affected by the toxin. In regenerating endothelial cells there may be a selective impairment of the G-protein-dependent mechanism for releasing EDRF, which may predispose the blood vessel to vasospasm or the initiation of vascular disease.
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PMID:G-proteins and endothelial responses. 212 22

We have examined the possible involvements of pertussis toxin (PT)-sensitive guanosine triphosphate (GTP)-binding protein (Gp) and protein kinase C (PKC) in the mitogenic signaling pathways of various growth factors by the use of PT-pretreated and/or 12-O-tetradecanoyl phorbol-13-acetate (TPA)-pretreated mouse fibroblasts. Effects of PT pretreatment (inactivation of PT-sensitive Gp) and TPA pretreatment (depletion of PKC) on mitogen-induced DNA synthesis varied significantly and systematically in response to growth factors: mitogenic responses of cells to thrombin, bombesin, and bradykinin were almost completely abolished both in PT- and TPA-pretreated cells; responses to epidermal growth factor (EGF), platelet-derived growth factor (PDGF), and vanadate were reduced to approximately 50% both in PT- and TPA-pretreated cells compared with native cells; response to basic fibroblast growth factor (bFGF) was not affected in PT-pretreated cells but was inhibited to some extent in TPA-pretreated cells. Thus, growth factors examined have been classified into three groups with regard to the involvements of PT-sensitive Gp and PKC in their signal transduction pathways. Binding of each growth factor to its receptor was not affected significantly by pretreatment of cells with PT or TPA. Inhibitory effects of PT and TPA pretreatment on each mitogen-induced DNA synthesis were not additive, suggesting that the functions of PT-sensitive Gp and PKC lie on an identical signal transduction pathway. Although all three groups of mitogens activated PKC, signaling of each growth factor depends to a varying extent on the function of PKC. Our results indicate that a single peptide growth factor such as EGF, PDGF, or bFGF acts through multiple signaling pathways to induce cell proliferation.
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PMID:Mitogenic signaling pathways of growth factors can be distinguished by the involvement of pertussis toxin-sensitive guanosine triphosphate-binding protein and of protein kinase C. 212 94

Addition of thrombin (Thr) or adenosine triphosphate (ATP) to rat aortic smooth muscle cells in culture (A-10, ATCC CRL 1476) induced rapid formation of inositol phosphates and release of intracellular calcium. These responses depended on the concentration of Thr and ATP used. The Thr effect was blocked by the Thr antagonist, hirudin. ADP was almost as effective as ATP, but AMP was ineffective in mediating the effects. Pretreatment of the cells with pertussis toxin (PT) resulted in partial (60-70%) inhibition of Thr- and ATP-mediated calcium release, suggesting that in smooth muscle cells, Thr and ATP (purinergic P2) receptors are coupled to phosphoinositide specific PLC (PI-PLC) through PT-sensitive guanine nucleotide binding (G) proteins.
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PMID:Involvement of pertussis toxin sensitive GTP binding protein in adenosine triphosphate and thrombin-mediated responses in vascular smooth muscle cells. 215 72


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