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)

Prostaglandin E2 (PGE2) is the major renal cyclooxygenase metabolite of arachidonic acid. Urinary excretion of PGE2 is increased by dietary salt restriction, as well in cirrhosis and congestive heart failure. To determine whether urinary PGE2 affects transport along the nephron, the actions of luminal PGE2 were studied in the isolated perfused rabbit cortical collecting duct (CCD). Luminal PGE2 transiently hyperpolarized transepithelial voltage (Vt) in a dose-dependent manner (half-maximal effect approximately 10(-8) M) in contrast to a sustained depolarization of Vt produced by basolateral PGE2. Luminal PGE2 (0.1 microM) also significantly stimulated osmotic water permeability in the CCD. In CCDs cultured on semipermeable supports, apical PGE2 stimulated adenosine 3',5'-cyclic monophosphate (cAMP) production, suggesting the effects of luminal PGE2 are mediated by adenylyl cyclase-stimulating EP2 or EP4 receptors. Sulprostone, a PGE2 analogue selective for EP1 and EP3 receptors, affected Vt only when applied from the basolateral but not the luminal surface. Luminal application of the EP2 receptor agonist butaprost was also without effect. These results suggest that luminal PGE2 affects Vt via a butaprost-insensitive EP4 receptor. The Vt effect of luminal PGE2 was not blocked by pertussis toxin, also arguing against an EP3-mediated Gi-coupled effect. Finally, 1 microM luminal PGE2 only slightly increased CCD intracellular calcium concentration ([Ca2+]i), in contrast to the marked increase in [Ca2+]i produced by basolateral PGE2 (0.1 microM).(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Luminal prostaglandin E receptors regulate salt and water transport in rabbit cortical collecting duct. 765

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.
 ...
PMID:Prostaglandin E2 activates phospholipase C and elevates intracellular calcium in cultured myometrial cells: involvement of EP1 and EP3 receptor subtypes. 864 Dec 11

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.
 ...
PMID:Characterization of the PGE2 receptor subtype in bovine chondrocytes in culture. 884 20

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.
 ...
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

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.
 ...
PMID:Prostaglandins induce proliferation of rat hepatocytes through a prostaglandin E2 receptor EP3 subtype. 912 80

Prostaglandins (PGs) exert their effects via binding to specific cell surface receptors and influencing second messenger systems through G-proteins. PGE2 may interact with at least four receptor subtypes (EP1, EP2, EP3, EP4), each showing different pharmacological profiles. The second messengers calcium, inositol phosphates (InsPs) and cyclic nucleotides play decisive roles in uterine contractility. The question in this investigation was, which EP receptors, G-proteins and second messenger systems transmit PGE2 induced signals in human myometrium. We have measured changes in InsPs and cAMP formation and also in intracellular calcium concentration ([Ca2+]i) induced by PGE2 and receptor subtype selective analogues in cultured human myometrial cells. PGE2 increased cAMP level and this effect was shared by the EP2 receptor subtype selective agonist Butaprost and by Misoprostol (EP3 > EP2 > EP1). Sulprostone (EP3 > EP1) did not stimulate adenylyl cyclase activity per se, but inhibited forskolin-stimulated adenylyl cyclase in a pertussis toxin (PT) sensitive way. PGE2, GR63799X (EP3 selective), Sulprostone and Misoprostol activated phospholipase-C (PLC), this effect was resistant to PT treatment. PGE2 also elevated [Ca2+]i from the resting level of 60-90 nM up to 350 nM. Low concentrations (1-300 nM) of PGE2 increased [Ca2+]i without PLC activation. The selective EP1 inhibitor AH6809, Nifedipine, Verapamil and PT treatment inhibited this effect of PGE2. In cultured human myometrial cells PGE2 interacts with EP1 receptors, which elevate [Ca2+]i independently from PLC, but involving a Gi protein and plasmamembrane calcium channels; EP2 receptors which stimulate adenylyl cyclase; EP3A receptors, which inhibit adenylyl cyclase activity through Gi activation and EP3D receptors which activate PLC through a PT-insensitive pathway and also elevate [Ca2+]i.
 ...
PMID:Prostaglandin E receptors in myometrial cells. 953 Apr 35

We examined the contribution of specific EP receptors in regulating cell growth. By RT-PCR and northern hybridization, adult human keratinocytes express mRNA for three PGE2 receptor subtypes associated with cAMP signaling (EP2, EP3, and small amounts of EP4). In actively growing, non-confluent primary keratinocyte cultures, the EP2 and EP4 selective agonists, 11-deoxy PGE1 and 1-OH PGE1, caused complete reversal of indomethacin-induced growth inhibition. The EP3/EP2 agonist (misoprostol), and the EP1/EP2 agonist (17-phenyl trinor PGE2), showed less activity. Similar results were obtained with agonist-induced cAMP formation. The ability of exogenous dibutyryl cAMP to completely reverse indomethacin-induced growth inhibition support the conclusion that growth stimulation occurs via an EP2 and/or EP4 receptor-adenylyl cyclase coupled response. In contrast, activation of EP3 receptors by sulprostone, which is virtually devoid of agonist activity at EP2 or EP4 receptors, inhibited bromodeoxyuridine uptake in indomethacin-treated cells up to 30%. Although human EP3 receptor variants have been shown in other cell types to markedly inhibit cAMP formation via a pertussis toxin sensitive mechanisms, EP3 receptor activation and presumably growth inhibition was independent of adenylyl cyclase, suggesting activation of other signaling pathways.
 ...
PMID:Growth regulation of primary human keratinocytes by prostaglandin E receptor EP2 and EP3 subtypes. 953 79

We previously showed that prostaglandin E2 (PGE2) stimulates multiple intracellular signaling pathways as follows: by activation of adenylate cyclase; phosphoinositide (PI)-hydrolyzing phospholipase C and phosphatidylcholine (PC)-hydrolyzing phospholipase D; and by induction of Ca2+ influx in osteoblast-like MC3T3-E1 cells. In this study, we investigated the effect of PGE2 on the synthesis of interleukin-6 (IL-6) and its regulatory mechanism in MC3T3-E1 cells. PGE2 significantly stimulated IL-6 secretion in a dose-dependent manner in the range between 1 nmol/L and 10 micromol/L. A23187, a calcium ionophore, or dibutyryl-cAMP significantly induced IL-6 secretion. The effect of a combination of A23187 and dibutyryl-cAMP on IL-6 secretion was additive. The depletion of extracellular Ca2+ by EGTA reduced the PGE2-induced IL-6 secretion. EP1 receptor antagonist inhibited the PGE2-induced IL-6 secretion. H-89, an inhibitor of cAMP-dependent protein kinase, decreased the PGE2-induced IL-6 secretion. EP2 receptor agonist alone stimulated IL-6 secretion. However, EP4 receptor antagonist had little effect on IL-6 secretion. Calphostin C, a specific inhibitor of protein kinase C (PKC), enhanced the secretion of IL-6 induced by PGE2. The stimulative effect of PGE2 on IL-6 secretion was significantly enhanced in PKC downregulated MC3T3-E1 cells. Pertussis toxin enhanced PGE2-induced IL-6 secretion. These results strongly suggest that PGE2 stimulates IL-6 synthesis through both Ca2+ mobilization from extracellular space via EP1 receptor and cAMP production via EP2 receptor in osteoblast-like cells, and that the PKC activation by PGE2 itself regulates oversynthesis of IL-6.
 ...
PMID:Interleukin-6 synthesis induced by prostaglandin E2: cross-talk regulation by protein kinase C. 955 35

The effects of prostaglandin E2 are thought to be mediated via G protein-coupled plasma membrane receptors, termed EP. However recent data implied that prostanoids may also act intracellularly. We investigated if the ubiquitous EP3 and the EP4 receptors are localized in nuclear membranes. Radioligand binding studies on isolated nuclear membrane fractions of neonatal porcine brain and adult rat liver revealed the presence of EP3 and EP4. A perinuclear localization of EP3alpha and EP4 receptors was visualized by indirect immunocytofluorescence and confocal microscopy in porcine cerebral microvascular endothelial cells and in transfected HEK 293 cells that stably overexpress these receptors. Immunoelectron microscopy clearly revealed EP3alpha and EP4 receptors localization in the nuclear envelope of endothelial cells; this is the first demonstration of the nuclear localization of these receptors. Data also reveal that nuclear EP receptors are functional as they affect transcription of genes such as inducible nitric-oxide synthase and intranuclear calcium transients; this appears to involve pertussis toxin-sensitive G proteins. These results define a possible molecular mechanism of action of nuclear EP3 receptors.
 ...
PMID:Localization of functional prostaglandin E2 receptors EP3 and EP4 in the nuclear envelope. 1033 71

Growth plate chondrocyte function is modulated by the vitamin D metabolite 1alpha,25-(OH)(2)D(3) via activation of protein kinase C (PKC). In previous studies with cells derived from prehypertrophic and upper hypertrophic zones of rat costochondral cartilage (growth zone cells), inhibition of prostaglandin production with indomethacin caused a decrease in the stimulation of PKC activity, suggesting that changes in prostaglandin levels mediate the 1alpha,25-(OH)(2)D(3)-dependent response in these cells. Growth zone cells also respond to PGE(2) directly, indicating that prostaglandins act as autocrine or paracrine regulators of chondrocyte metabolism in the growth plate. The aim of the present study was to identify which PGE(2) receptor subtypes (EP) mediate the effects of PGE(2) on growth zone cells. Using primers specific for EP1-EP4, reverse transcription-polymerase chain reaction (RT-PCR) amplified EP1 and EP2 cDNA in a RT-dependent manner. In parallel experiments, we used EP subtype-specific agonists to examine the role of EP receptors in 1alpha,25-(OH)(2)D(3)-mediated cell proliferation and differentiation. 17-Phenyl-trinor-PGE(2) (PTPGE(2)), an EP1 agonist, decreased [3H]-thymidine incorporation in a dose-dependent manner and augmented the 1alpha,25-(OH)(2)D(2)-induced inhibition of [3H]-thymidine incorporation. PTPGE(2) also caused significant increases in proteoglycan production, as measured by [35S]-sulfate incorporation, and alkaline phosphatase specific activity. 1alpha,25-(OH)(2)D(3)-induced alkaline phosphatase activity was only slightly stimulated by PTPGE(2). In contrast, 1alpha,25-(OH)(2)D(3)-induced PKC activity was synergistically increased by PTPGE(2), whereas EP1 antagonists SC-19220 and AH6809 inhibited PKC activity in a dose-dependent manner. The EP2, EP3 and EP4 agonists had no effect on the various cell-induced responses measured. EP1 receptor-induced responses were blocked by the phospholipase C inhibitor U73122, and reduced by PKA inhibitors. EP1 receptor-induced PKC activity was insensitive to pertussis toxin or choleratoxin but blocked by the G-protein inhibitor GDPbetaS, suggesting the involvement of G(q). These results suggest that the EP1 receptor subtype mediates various PGE(2)-induced cellular responses in growth zone chondrocytes leading to decreased proliferation and enhanced differentiation, as well as the effect of 1alpha,25-(OH)(2)D(3) on cellular maturation.
 ...
PMID:Characterization of PGE(2) receptors (EP) and their role as mediators of 1alpha,25-(OH)(2)D(3) effects on growth zone chondrocytes. 1159 7


1 2 Next >>