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

PGE2 is a powerful modulator of uterine contractility, but there is uncertainty as to which receptor subtypes (EP1, EP2, EP3, or EP4), G proteins, and second messenger systems are activated by PGE2 in myometrium. Here we show that in cultured human myometrial cells, PGE2 (1-100 microM) activates phospholipase C (PLC) up to 500% over the control level and elevates intracellular calcium ([Ca2+]i) from the resting level of 60-90 nM up to 350 nM in a concentration-dependent manner. Stimulation by the receptor subtype-selective analogs GR63799X (EP3), sulprostone (EP3 > EP1), and misoprostol (EP3 > EP2 > EP1) indicates that these effects are transmitted through EP3 receptors. Both effects are resistant to pertussis toxin (PT). Lower concentrations of PGE2 (1-300 nM) increase [Ca2+]i via a PT-sensitive pathway, without PLC activation. This [Ca2+]i increase occurs after an inverse dose-related delay and is inhibited by the selective EP1 antagonist AH6809 and calcium channel blockers. By comparison, oxytocin stimulates PLC up to 1000% over the control level and elevates [Ca2+]i up to 800 nM in a concentration-dependent manner without any measurable delay; both effects are partly sensitive to PT. These data provide functional evidence for the presence of different stimulatory mechanisms for PGE2 in myometrium: 1) a low affinity receptor (probably EP3D) that activates PLC through a PT-insensitive pathway; and 2) a high affinity receptor (probably EP1), independent from PLC and involving a PT-sensitive G protein (G(i)?). Both pathways lead to elevation of [Ca2+]i.
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PMID:Prostaglandin E2 activates phospholipase C and elevates intracellular calcium in cultured myometrial cells: involvement of EP1 and EP3 receptor subtypes. 864 Dec 11

To elucidate the role of specific proinflammatory cytokines in regulating airway responsiveness, we examined the effects and mechanisms of action of IL-1beta, TNF-alpha, and IL-2 on the beta-adrenoceptor- and postreceptor-coupled transmembrane signaling mechanisms regulating relaxation in isolated rabbit tracheal smooth muscle (TSM) segments. During half-maximal isometric contraction of the tissues with acetylcholine, relaxation responses to isoproterenol, PGE2, and forskolin were separately compared in control (untreated) TSM and tissues incubated for 18 h with IL-1beta (10 ng/ml), TNF-(alpha (100 ng/ml), or IL-2 (200 ng/ml). Relative to controls, IL-1beta- and TNF-alpha-treated TSM, but not IL-2-treated tissues, depicted significant attenuation of their maximal relaxation and sensitivity (i.e., -log dose producing 50% maximal relaxation) to isoproterenol (P < 0.001) and PGE2 (P < 0.05); whereas the relaxation responses to direct stimulation of adenylate cyclase with forskolin were similar in the control and cytokine-treated tissues. Further, the attenuated relaxation to isoproterenol and PGE2 was ablated in the IL-1beta-treated TSM that were pretreated with either the muscarinic M2-receptor antagonist, methoctramine (10(-6) M), or pertussis toxin (100 ng/ml). Moreover, Western immunoblot analysis demonstrated that: (a) Gi protein expression was significantly enhanced in membrane fractions isolated from IL-1beta-treated TSM; and (b) the latter was largely attributed to induced enhanced expression of the Gi alpha2 and Gi alpha3 subunits. Collectively, these observations provide new evidence demonstrating that IL-lbeta and TNF-alpha induce impaired receptor-coupled airway relaxation in naive TSM, and that the latter effect is associated with increased muscarinic M2-receptor/Gi protein-coupled expression and function.
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PMID:Mechanism of cytokine-induced modulation of beta-adrenoceptor responsiveness in airway smooth muscle. 864 53

Lipid bodies, lipid rich cytoplasmic inclusions, are characteristically abundant in vivo in leukocytes associated with inflammation. Because lipid bodies are potential reservoirs of esterified arachidonate and sites at which eicosanoid-forming enzymes may localize, we evaluated mechanisms of lipid body formation in neutrophils (PMN). Among receptor-mediated agonists, platelet activating factor (PAF), but not C5a, formyl-methyl-phenylalanine, interleukin 8, or leukotriene (LT) B4, induced the rapid formation of lipid bodies in PMN. This action of PAF was receptor mediated, as it was dose dependently inhibited by the PAF receptor antagonist WEB 2086 and blocked by pertussis toxin. Lipid body induction by PAF required 5-lipoxygenase (LO) activity and was inhibited by the 5-lipoxygenase-activating protein antagonist MK 886 and the 5-LO inhibitor zileuton, but not by cyclooxygenase inhibitors. Corroborating the dependency of PAF-induced lipid body formation on 5-LO, PMN and macrophages from wild-type mice, but not from 5-LO genetically deficient mice, formed lipid bodies on exposure to PAF both in vitro and in vivo within the pleural cavity. The 5-LO product inducing lipid body formation was not LTB4 but was 5(S)-hydroxyeicosatetraenoic acid [5(S)-HETE], which was active at 10-fold lower concentrations than PAF and was also inhibited by pertussis toxin but not by zileuton or WEB 2086. Furthermore, 5-HETE was equally effective in inducing lipid body formation in both wild-type and 5-LO genetically deficient mice. Both PAF- and 5(S)-HETE-induced lipid body formation were inhibited by protein kinase C (PKC) inhibitors staurosporine and chelerythrine, the phospholipase C (PLC) inhibitors D609 and U-73122, and by actinomycin D and cycloheximide. Prior stimulation of human PMN with PAF to form lipid bodies enhanced eicosanoid production in response to submaximal stimulation with the calcium ionophore A23187; and the levels of both prostaglandin (PG) E2 and LTB4 correlated with the number of lipid bodies. Furthermore, pretreatment of cells with actinomycin D or cycloheximide inhibited not only the induction of lipid body formation by PAF, but also the PAF-induced "priming" for enhanced PGE2 and LTB4 in PMN. Thus, the compartmentalization of lipids to form lipid bodies in PMN is dependent on specific cellular responses that can be PAF receptor mediated, involves signaling through 5-LO to form 5-HETE and then through PKC and PLC, and requires new protein synthesis. Since increases in lipid body numbers correlated with priming for enhanced PGE2 and LTB4 production in PMN, the induction of lipid bodies may have a role in the formation of eicosanoid mediators by leukocytes involved in inflammation.
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PMID:Mechanisms of platelet-activating factor-induced lipid body formation: requisite roles for 5-lipoxygenase and de novo protein synthesis in the compartmentalization of neutrophil lipids. 866 9

1. Prostaglandin E2 (PGE2) is an autacoid that decreases proteoglycan synthesis, increases metalloprotease production by cultured chondrocytes, and can modulate some of the actions of interleukin-1 on cartilage. The objective of the present study was to characterize the subtype of prostaglandin E2 receptor present in bovine chondrocytes in culture. 2. Primary cultures of articular chondrocytes were prepared from slices of bovine carpal cartilage by sequential digestion with type III hyaluronidase, trypsin, type II collagenase, followed by overnight incubation in Dulbecco's Modified Eagle's Medium (DMEM) with type II collagenase, washing, and seeding at a density of 2 x 10(5) cells cm-2 in DMEM with 10% foetal bovine serum. 3. PGE2 and carbaprostacyclin induced dose-dependent increases in intracellular cyclic AMP in bovine chondrocytes in culture. The potencies of these compounds were different, and maximal doses of PGE2 and carbaprostacyclin had an additive effect. PGD2 induced a small increase in intracellular cyclic AMP only at a high concentration (10(-5) M). 4. PGE2 was more potent that the EP2 agonist 11-deoxy-PGE1 at inducing increases in intracellular cyclic AMP. The EP2 agonist butaprost, however, induced only a small increase at a concentration of 10(-5)M. 17-Phenyl-PGE2 (EP1 agonist), sulprostone and MB 28767 (15S-hydroxy-9-oxo-16-phenoxy-omega-tetranorprost-13E-enoic acid) (EP3 agonists) did not induce an increase in intracellular cyclic AMP at concentrations up to 10(-5)M. 5. The EP4 antagonist AH 23848B ([1 alpha(Z),2 beta, 5 alpha]-(+/-) -7-[5-[[(1,1'-biphenyl)-4-yl]methoxyl-2-(4-morpholinyl) -3-oxocyclopentyl]-5-heptenoic acid) antagonized PGE2 but not carbaprostacyclin effects on intracellular cyclic AMP. The Schild plot slope was different from 1 but this could be due to an interaction of PGE2 with IP receptors in high doses. The exact nature of the antagonism by compound AH 23848B could not be definitely established in these experimental conditions. 6. Neither PGE2 nor any of its analogues inhibited the increase in intracellular cyclic AMP induced by forskolin, and pertussis toxin did not alter the response to PGE2, suggesting that no Gi-coupled PGE2 receptors are present in these cells. Stimulation with PGE2 did not induce significant increases in intracellular inositol-trisphosphate levels nor increases in intracellular free calcium as determined by confocal microscopy, suggesting the absence of phospholipase-C-coupled or of calcium channel-coupled PGE2 receptors in bovine chondrocytes in these experimental conditions. 7. These results show for the first time that bovine chondrocytes in culture present a functional PGE2 receptor that has some pharmacological characteristics of an EP4 subtype, as well as an IP receptor.
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PMID:Characterization of the PGE2 receptor subtype in bovine chondrocytes in culture. 884 20

Prostaglandin E receptor EP3 subtype is widely distributed in the nervous system and is specifically localized to neurons, suggesting that the EP3 receptor plays important roles in the nervous system. We established a PC12 cell line that stably expresses the EP3B receptor isoform isolated from bovine adrenal chromaffin cells and examined the effect of agonist stimulation on the neuronal morphology of the PC12 cells. In the differentiated cells, M&B28767, an EP3 agonist, caused neurite retraction in a pertussis toxin-insensitive manner. 12-O-Tetradecanoylphorbol-13-acetate (TPA) also induced neurite retraction. However, when protein kinase C was down-regulated by long term exposure to TPA, TPA failed to induce neurite retraction, while the EP3B receptor-mediated retraction occurred normally. Clostridium botulinum C3 exoenzyme completely inhibited both EP3 agonist- and TPA-induced neurite retraction when microinjected into the cells, indicating that the morphological effect of the EP3B receptor is dependent on Rho activity. Thus, the activation of the EP3B receptor induced neurite retraction through a protein kinase C-independent Rho-activation pathway.
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PMID:Prostaglandin E receptor EP3 subtype induces neurite retraction via small GTPase Rho. 893 15

We have previously shown that 24,25-(OH)2D3 plays a major role in resting zone (RC) chondrocyte differentiation and that this vitamin D metabolite regulates protein kinase C (PKC). The aim of the present study was to identify the signal transduction pathway used by 24,25-(OH)2D3 to stimulate PKC activation. Confluent, fourth passage RC cells from rat costochondral cartilage were used to evaluate the mechanism of PKC activation. Treatment of RC cultures with 24,25-(OH)2D3 for 90 min produced a dose-dependent increase in diacylglycerol (DAG). Addition of R59022, a diacylglycerol kinase inhibitor, significantly increased PKC activity in cultures treated with 24,25-(OH)2D3. Addition of dioctanoylglycerol (DOG) to plasma membranes isolated from RC increased PKC activity 447-fold. Addition of pertussis toxin or cholera toxin to control cultures elevated basal PKC activity. When added together with 10(-9) M 24,25-(OH)2D3, there was an additive effect on PKC activity but in cultures treated with 10(-8) M 24,25-(OH)2D3, only the hormone-dependent stimulation of PKC was observed. The phospholipase C inhibitor, U73-122, had no effect on PKC activity, indicating that the DAG produced in response to 24,25-(OH)2D3 is not derived from phosphatidylinositol. Addition of the tyrosine kinase inhibitor, genistein, also had no effect on 24,25-(OH)2D3-stimulated PKC, further supporting the hypothesis that phospholipase C is not involved in the mechanism and that phospholipase D is responsible for the increase in DAG production. Phospholipase A2 inhibitors, quinacrine and AACOCF3, and the cyclooxygenase inhibitor indomethacin increased PKC activity in the RC cultures. Exogenous PGE2, one of the downstream products of phospholipase A2 action, inhibited PKC activity. These results suggest that 24,25-(OH)2D3 regulates PKC activity by two distinct phospholipid-dependent mechanisms: production of DAG via phospholipase D and inhibition of the production of PGE2 via inhibition of phospholipase A2 and cyclooxygenase.
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PMID:24,25-(OH)2D3 regulates protein kinase C through two distinct phospholipid-dependent mechanisms. 895

Prostaglandin E2 receptors (EPR) belong to the family of G-protein-coupled receptors with 7 transmembrane domains. They form a family of four subtypes, which are linked to different G-proteins. EP1R are coupled to Gq, EP2 and EP4R to Gs and EP3R to Gi. Different C-terminal splice variants of the bovine EP3R are coupled to different G-proteins. A mouse EP3R whose C-terminal domain had been partially truncated no longer showed agonist-induced Gi-protein activation and was constitutively active. In order to test the hypothesis that the C-terminal domain confers coupling specificity of the receptors on the respective G-proteins, a cDNA for a hybrid rEP3hEP4R, containing the N-terminal main portion of the Gi-coupled rat EP(3beta)R including the 7th transmembrane domain and the intracellular C-terminal domain of the Gs-coupled human EP4R, was generated by PCR. HEK293 cells transiently transfected with the chimeric rEP3hEP4R cDNA expressed a plasma membrane PGE2 binding site with a slightly lower Kd value for PGE2 but an identical binding profile for receptor-specific ligands as cells transfected with the native rat EP(3beta)R. In HepG2 cells stably transfected with the chimeric rEP3hEP4R cDNA PGE2 did not increase cAMP formation characteristic of Gs coupling but attenuated the forskolin-stimulated cAMP synthesis characteristic of Gi coupling. This effect was inhibited by pre-treatment of the cells with pertussis toxin. Thus, the hybrid receptor behaved both in binding and in functional coupling characteristics as the native rat EP(3beta)R. Apparently, the intracellular C-terminal domain did not confer coupling specificity but coupling control, i.e. allowed a signalling state of the receptor only with agonist binding.
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PMID:The C-terminal domain of the Gs-coupled EP4 receptor confers agonist-dependent coupling control to Gi but no coupling to Gs in a receptor hybrid with the Gi-coupled EP3 receptor. 901 84

Interstitial fluid flow may play a role in load-induced bone remodeling. Previously, we have shown that fluid flow stimulates osteoblast production of cAMP inositol trisphosphate (IP3), and PGE2. Flow-induced increases in cAMP and IP3 were shown to be a result of PG production. Thus, PGE2 production appears to be an important component in fluid flow induced signal transduction. In the present study, we investigated the mechanism of flow-induced PGE2 synthesis. Flow-induced a 20-fold increase in PGE2 production in osteoblasts. Increases were also observed with ALF4-(10mM) (98-fold), an activator of guanidine nucleotide-binding proteins (G proteins), and calcium ionophore A23187 (2 microM) (100-fold) in stationary cells. We then investigated whether flow stimulation is mediated by G proteins and increases in intracellular calcium. Flow-induced PGE2 production was inhibited by the G protein inhibitors GDP beta S (100 microM) and pertussis toxin (1 microgram/ml) by 83% and 72%, respectively. Chelation of extracellular calcium by EGTA (2 mM) and intracellular calcium by quin-2/AM (30 microM) blocked flow stimulation by 87% and 67%, respectively. These results suggest that G proteins and calcium play an important role in mediating mechanochemical signal transduction in osteoblasts.
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PMID:Activation of G proteins mediates flow-induced prostaglandin E2 production in osteoblasts. 904 3

We characterized the proliferative action of prostaglandins (PGs) in relation to their membrane receptors on rat hepatocytes in primary culture. PGs in the order 16,16-dimethyl PGE2 > PGE2 > PGF2alpha >> PGD2 augmented epidermal growth factor (EGF)/insulin-induced DNA synthesis, assessed by [(3)H]thymidine incorporation, in a concentration-dependent manner, whereas PGs alone did not stimulate basal DNA synthesis without EGF and insulin. The cells exhibited [(3)H]PGE2 binding sites that were displaced by unlabeled PGs in the order PGE1 = PGE2 > PGF2alpha > PGD2. PGE2 inhibited glucagon-stimulated adenosine 3',5'-cyclic monophosphate (cAMP) accumulation concentration dependently. The mean effective concentration for DNA synthesis, median inhibitory concentration for cAMP accumulation, and dissociation constant for [(3)H]PGE2 binding at 25 degrees C were almost identical (approximately 70 nM). Treatment of the cells with pertussis toxin (100 ng/ml), which ADP-ribosylated most of the 41-kDa substrate, abolished the proliferative effects of PGs. We detected the expression of mRNA of the EP3 subtype PGE2 receptor using reverse transcription-polymerase chain reaction. Moreover, an EP3 agonist, enprostil, but not the EP1 agonist 17-phenyl-trinor-PGE2 or the EP2/EP4 agonist 11-deoxy-PGE1, stimulated EGF/insulin-induced DNA synthesis. These results indicate that PGs act as comitogenic growth factors through the EP3 subtype PGE2 receptor coupled with G(i) protein in cultured rat hepatocytes.
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PMID:Prostaglandins induce proliferation of rat hepatocytes through a prostaglandin E2 receptor EP3 subtype. 912 80

In the present study we have examined the effects and mechanisms of endothelin-1 (ET-1) on arachidonic acid (AA) release and prostaglandin (PG) synthesis in human ciliary muscle (HCM) cells. ET-1 stimulated AA release in a time (t1/2=1.5 min) and concentration-dependent (EC50=5 nM) manner, which is primarily mediated through the ETA receptor subtype. The AA liberated by ET-1 appears to derive mainly from the phosphoinositides and phosphatidylcholine. Our data show that phospholipase A2 (PLA2), but not phospholipase C (PLC), plays an important role in ET-1-induced AA release. This conclusion is supported by the following findings: (1) ET-1-evoked AA release was inhibited by the PLA2 inhibitors dexamethasone, mepacrine and manoalide in a concentration-dependent manner. Conversion of AA into PGE2 was inhibited by the cyclooxygenase inhibitors in the following order: Indomethacin>naproxen >ibuprofen>NS-398>aspirin. (2) The phorbol ester, PDBu, an activator of protein kinase C, potentiated ET-1-induced AA release by 39%, but inhibited that of inositol phosphates formation by 62%. (3) Pretreatment of the labeled cells with isoproterenol lowered ET-1-induced inositol phosphates production, but had no effect on AA release. (4) U71322, a PLC inhibitor, inhibited ET-1-induced inositol phosphates production, but had no effect on that of AA release. (5) Pretreatment of the cells with pertussis toxin (0.1 microg ml-1) attenuated the stimulatory effects of ET-1 on AA release and PGE2 formation. These data demonstrate that ET-1 is a potent agonist for AA release and PG synthesis in HCM cells, and that PLA2, but not PLC, plays an important role in ET-1-induced AA release and PG synthesis. In ciliary muscle, AA and its metabolites play important roles in intracellular signalling, modulation of physiological processes, and regulation of intraocular pressure.
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PMID:Endothelin-1 stimulates the release of arachidonic acid and prostaglandins in cultured human ciliary muscle cells: activation of phospholipase A2. 923 67


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