Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effect of endothelin-1 (ET-1) on arachidonate metabolism in the respiratory epithelium was investigated in primary cultures of feline tracheal epithelial cells. Subconfluent epithelial cell cultures were stimulated by ET-1, and eicosanoid generation was determined by high performance liquid chromatography (HLPC) of 3H-labeled arachidonic acid (AA) metabolites and by radioimmunoassay (RIA) of corresponding nonradiolabeled HPLC elution. The HPLC chromatograms of [3H]AA-prelabeled samples revealed that ET-1 (10(-5) M) augmented the release of prostaglandin (PG) E2, 12-hydroxyeicosatetraenoic acid (HETE), PGF2 alpha, and AA. RIA of corresponding nonradiolabeled HPLC elution demonstrated a significantly increased release of PGE2, PGF2 alpha, and 12-HETE as well as 5-HETE in response to ET-1 stimulation. 5-HETE release from ET-1-stimulated cells was further identified by gas chromatography/mass spectrometry (GC/MS). The stimulating effect of ET-1 on AA metabolism was dose dependent (10(-5) to 10(-7) M) and peaked within 1 h with a progressive decline over the subsequent hours. Using 125I-labeled ET-1 as radioligand, the presence of specific binding sites for ET-1 was demonstrated in cultured feline tracheal epithelial cells. ET-1 binding reached equilibrium within 1 h at 37 degrees C. Scatchard analysis suggested the existence of two saturable binding sites, with the estimated equilibrium dissociation constant (Kd) of 35.3 pM and maximal binding capacity (Bmax) of 15.0 fmol/10(7) cells for the higher affinity binding site and Kd of 205.9 pM and Bmax of 35.0 fmol/10(7) cells for the lower affinity binding site.(ABSTRACT TRUNCATED AT 250 WORDS)
Am J Respir Cell Mol Biol 1993 Mar
PMID:Production of eicosanoids in response to endothelin-1 and identification of specific endothelin-1 binding sites in airway epithelial cells. 844 18

The fatty acid compositions of Malpighian tubules from adult females of the mosquito Aedes aegypti were determined for total lipids, phospholipids, triacylglycerols and three phospholipid fractions, namely phosphatidylcholine (PC), phosphatidylethanolamine (PE) and phosphatidylinositol/phosphatidylserine (PI/PS). The prostaglandin precursor arachidonic acid (20:4n-6) occurred in total lipids and phospholipids, but not triacylglycerols. Within phospholipids, nearly all of the 20:4n-6 was detected in PC, with only traces in PE, and none was detected in PI/PS. Isolated Malpighian tubules incorporated exogenous radioactive 20:4n-6 into tissue phospholipids and diacylglycerols, with most of the radioactivity recovered in diacylglycerol. These data indicate selective incorporation of 20:4n-6 into tissue lipids. PGE2 was detected in Malpighian tubule whole mounts by immunohistochemical staining. These findings support the idea that prostaglandins are physiologically active in mosquito Malpighian tubules.
Insect Biochem Mol Biol 1993 Jun
PMID:Arachidonic acid and prostaglandin E2 in Malpighian tubules of female yellow fever mosquitoes. 850 85

We report on prostaglandin (PG) biosynthesis in the lone star tick, Amblyomma americanum. In vitro preparations of whole female ticks and internal tissues were competent to biosynthesize four PGs: PGA2/PGB2, PGD2, PGE2, PGF2 alpha. PGA2/PGB2 was the major product under optimal conditions. PG biosynthesis by whole tick and internal tissues were sensitive to incubation conditions including, protein concentration, time, temperature, pH, and presence of a co-factor cocktail composed of reduced glutathione, hydroquinone, and hemoglobin. Under standard assay conditions, 2 mg/ml protein were incubated at pH 8.0 for 2 min at 32 degrees C. PG biosynthesis was inhibited by indomethacin, a potent cyclooxygenase inhibitor in mammalian systems. Internal tissue preparations were fractionated into cytosolic and microsomal preparations by ultracentrifugation. PG biosynthetic activity was detected in both fractions. The subcellular distribution of PG biosynthetic activity in ticks is similar to other invertebrates, but quite different from mammals, in which PG biosynthetic activity is almost exclusively localized in the microsomal fractions. PGH synthase-2 was detected in the microsomal fraction on western blot analysis. These results suggest that the lone star tick is competent to biosynthesize PGs. These compounds may contribute to the success of tick feeding ecology by attenuating the defense responses of vertebrate hosts during lengthy feeding periods.
Insect Biochem Mol Biol 1995 Oct
PMID:Prostaglandin biosynthesis and subcellular localization of prostaglandin H synthase activity in the lone star tick, Amblyomma americanum. 854 84

The E-series prostaglandins (PGEs) are complex lipid regulators of B lymphocyte function. They inhibit the growth of certain B lymphoma lines. We report that heterogeneity with respect to PGE-induced growth inhibition correlates with the maturation state of the B cell lines. Specifically, the pre-B cell line 70Z/3 and the immature lymphoma CH31 are extremely sensitive to PGE2. To a lesser degree, other immature lymphomas (CH33, ECH408.1 and WEHI-231) are sensitive to PGE2. More mature lymphomas (BAL-17, CH12 and CH27) and fully differentiated myelomas (J558 and MOPC-315) are insensitive to PGE2. It is unknown what subtype of PGE receptor(s) (EPs) are expressed by B lymphocytes. It is also unknown if modulation of EP receptor expression could account for the differences in the sensitivity of these B cell lines to PGE2. To investigate these issues, reverse transcriptase polymerase chain reaction, Northern blot and DNA sequencing analyses were employed to obtain a definitive EP receptor subtype profile for these B cell lines, and for normal splenic B lymphocytes. Both normal and transformed B lymphocytes express mRNA encoding EP1, EP3beta and EP4 subtypes of PGE receptors. The B lineage cells do not express EP3alpha nor EP3gamma mRNA. The B cell lines are clonal, indicating that EP1, EP3beta and EP4 mRNA are coexpressed. Surprisingly, quantitative differences in basal EP1, EP3beta and EP4 expression were not observed between B cell lines despite their differing susceptibilities to PGE-induced growth inhibition. Conversely, the polyclonal activator LPS selectively upregulates EP4 mRNA expression in the mature B cell line CH12, but not in the LPS-sensitive pre-B cell line, 70Z/3. The activator LPS does not affect EP1 nor EP3beta mRNA expression. Treatment with dbcAMP, an analog of cAMP, mimics PGE-induced growth inhibition indicating that Gs-coupled EP2 and/or EP4 receptors mediate this inhibitory signal. Indeed, EP2 agonists mimic PGE2-induced growth inhibition unlike IP, EP1 and EP3-selective agonists. These data indicate that EP2 receptors are sufficient for mediating PGE-induced growth inhibition of susceptible B lineage cells.
Mol Immunol 1996 Jan
PMID:A molecular analysis of PGE receptor (EP) expression on normal and transformed B lymphocytes: coexpression of EP1, EP2, EP3beta and EP4. 860 22

Histamine was one of the first inflammatory mediators thought to be important in the pathophysiology of asthma, but it is not now thought to be a mediator with primary importance in airway constriction. However, histamine has several effects that may be relevant. One of these effects, its immunoregulatory role, has been largely ignored in asthma. Thus, because mast cells (MC) are an important source of histamine and cytokines, the modulation by histamine of the release of one cytokine, tumor necrosis factor alpha (TNF alpha), was investigated. Rat peritoneal MC (PMC) were pretreated with different concentrations of histamine (10(-14) to 10(-4) M) for 2 h before being tested for their TNF alpha-dependent cytotoxicity. A concentration-dependent inhibition of cytotoxicity was observed from 21% at 10(-12) M to 38% at 10(-4) M, reaching a plateau at 10(-8) M. At least 1 h pretreatment with histamine or its presence throughout the cytotoxic assay was required for the inhibitory effect of histamine. This inhibition was abrogated by indomethacin or anti-PGE2, suggesting that PGE2 may be an important mediator in the inhibition of TNF alpha by histamine. To investigate the type of histamine receptor implicated in this effect, PMC were treated for 20 min with H1 (clemastine and diphenhydramine), H2 (ranitidine and cimetidine), or H3 (thioperamide) receptor antagonists before the addition of histamine. H2 or H3 antagonists abrogated the inhibitory effect of histamine on PMC TNF alpha-dependent cytotoxicity. Furthermore, blockage of H2 receptors with ranitidine increased the release of TNF alpha from PMC stimulated with antigen, suggesting that histamine released by MC within 10 min of antigen stimulation downregulates the subsequent release of TNF alpha from the same MC population. These results suggest that histamine may act as an autocrine regulator of cytokine release by MC and thus modulate inflammatory responses in allergic asthma.
Am J Respir Cell Mol Biol 1996 Jun
PMID:Histamine inhibits tumor necrosis factor alpha release by mast cells through H2 and H3 receptors. 865 90

Gallbladder cell cultures obtained from rabbits subjected to sham or 72 h of bile duct ligation (72 h BDL, cholecystitis model) were incubated with calcium ionophore (A23187), dibutyryl cAMP (cAMP), and phorbol 12,13-diacetate (phorbol) to determine the intracellular signal transduction mechanisms responsible for increased inflamed gallbladder eicosanoid synthesis. Incubation of sham and 72 h BDL cell cultures with A23187 or phorbol significantly increased, whereas cAMP decreased, release of 6-keto-PGF1 alpha, PGE2, thromboxane B2 (measured by enzyme immunoassay) in a dose-related manner. Seventy-two-hour BDL cell cultures contained a specific 2-fold increased level of prostacyclin synthase compared to sham cell cultures which was not altered by preincubation with A23187, phorbol or cAMP. These findings suggest that increased PGI2 release in the sham and inflamed cell cultures following A23187 and phorbol stimulation was mediated in part via the inositol triphosphate pathway and protein kinase C activation and was not associated with altered cyclooxygenase or prostacyclin synthase content.
Mol Cell Endocrinol 1995 Nov 30
PMID:Regulation of eicosanoid synthesis in fibroblasts from inflamed gallbladders. 867 62

The human amnion may be an important source of prostaglandins involved in the onset of labour. Glucocorticoids are possible regulators of amnion prostaglandin synthesis and have been shown to stimulate the PGE2 output and prostaglandin H2 synthase (PGHS) activity of human amnion cells maintained in primary monolayer culture. There are two known isoforms of PGHS: the constitutively expressed PGHS-1 and the inducible PGHS-2. Recent studies have shown that the latter isoform is induced by glucocorticoids. The amnion consists of a single layer of epithelial cells beneath which lies a mesenchymal layer containing fibroblasts and it is not known which cell types are responding to glucocorticoids in this manner. In the present study, we demonstrate that although both cell types are present in culture, PGHS-2 protein and mRNA levels increase exclusively within the fibroblasts in response to dexamethasone, while PGHS-1 protein and mRNA levels remain unaffected in both cell types. These results suggest that the stimulation of PGE2 in cultured amnion cells by glucocorticoids is due to an upregulation of PGHS-2 gene transcription in fibroblasts, and that these previously overlooked cells may have important roles to play in the synthesis of prostaglandins involved in labour.
Mol Cell Endocrinol 1996 Mar 25
PMID:Glucocorticoids stimulate prostaglandin H synthase type-2 (PGHS-2) in the fibroblast cells in human amnion cultures. 873 73

Changes were investigated in prostanoid contents in cecal mucosa of rats fed with guar gum, a fiber diet. The rats were divided into 3 groups, the control group fed non-fiber diet and 2 groups fed respectively diets containing 7.5% and 15% of guar gum. Twelve rats in each group were sacrificed 10, 20, and 30 days respectively after initiation of diets, and length and weight of cecum and prostanoid contents in cecal mucosa were determined. The length and weight of cecum increased significantly 10 days after commencement of the fiber diets, and more remarkable changes were observed in the 15% fiber diet group. The ratio of prostaglandin (PG) E2 to PGD2 (PGE2/PGD2) was also increased by the content of guar gum dependently. These results suggest that alteration in prostanoid profiles is implicated in the fiber diet-induced enlargement of large bowels.
Biochem Mol Biol Int 1996 Mar
PMID:Effects of dietary fiber on prostanoid concentrations in cecal mucosa of rats. 882 2

We isolated a cDNA clone encoding the human prostaglandin (PG) E receptor EP4 subtype and examined the gene expression in human blood cells. Northern blot analysis revealed that the EP4 gene is expressed at a high level in peripheral blood mononuclear cells, and at lower levels in cultured human blood cell lines, THP-1 and U937 (monocytoid cell lines), MOLT-4 and Jurkat (T-cell lines), and Raji (B-cell line). To examine regulation of the EP4 gene expression in the immune system, we studied the effects of phorbol 12-myristate 13-acetate (PMA) on these cell lines. Gene expression was upregulated in THP-1, U937, and Raji cells by PMA, and was downregulated in MOLT-4 and Jurkat cells. In THP-1 cells the effects of PMA were further analyzed, and the upregulation of the EP4 gene was shown to be followed by an increase in PGE2 binding sites and in PGE2-induced cAMP accumulation. In the striking contrast, other PGE receptor subtypes (EP1, EP2 and EP3) and other prostanoid receptors (IP and DP) were shown not to be upregulated by PMA. Therefore, this is the first demonstration of a highly specific upregulation of the EP4 subtype in THP-1 cells treated with PMA, suggesting the importance of the EP4 subtype in the immune system. In the present study we also clarified that EP4 gene expression is regulated differently among human monocytoid and lymphoid lineage cells, thus leading to the better understanding of the regulatory mechanisms for the human EP4 gene expression in the immune system.
J Mol Med (Berl) 1996 Jun
PMID:Gene expression of the human prostaglandin E receptor EP4 subtype: differential regulation in monocytoid and lymphoid lineage cells by phorbol ester. 886 14

We recently identified a broadly expressed transporter, PGT, that transports primarily prostaglandins E2 and F2 alpha (PGE2 and PGF2 alpha). In the current study, we examined the structural determinants of potential PGT substrates in detail. Rat PGT was transiently expressed in HeLa cells, the timed uptake of tracer PGE2 was determined in the presence of various concentrations of unlabeled prostanoids; and the resulting inhibitory constants (Ki) were determined by curve-fitting. PGE2 and PGF2 alpha, both known to be transported, had similar affinities for PGT (Ki = 49-50 nM). The strongest interaction (Ki = 13-19 nM) was obtained with prostanoids lacking the 9- or 11-position oxygen groups. A relatively high affinity was also obtained for the bicycloendoperoxides U44069, PGH2, and U46619 (Ki = 29-39 nM). However, a radioactive representative from this group, U46619, was not transported. Structural modifications that produced a moderately reduced affinity relative to that of PGE2 (Ki = 56-286 nM) included reduction in C5 = C6, the addition of a benzene group at position C18, and isomerization at the C8 position. In complementary studies, tracer isoprostane B-iso-PGF2 alpha was found to be transported at approximately 13% the rate of tracer PGE2. Substantially weaker interaction (Ki = > 700 nM) was seen when the 1-position COO- anionic group was neutralized or when the 15(S)-OH group was changed to 15(R)-OH or to 15-keto. These results with the cloned rat PGT are very similar to those previously reported in the in vitro perfused rat lung and indicate that PGT probably represents the predominant route by which certain prostanoids, including F2 isoprostanes, are transported across plasma membranes.
Mol Pharmacol 1996 Oct
PMID:Structural determinants of substrates for the prostaglandin transporter PGT. 886 17


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