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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Human prostaglandin G/H synthase (hPGHS)-1 and hPGHS-2, key enzymes in the formation of prostanoids from arachidonic acid, were expressed at high levels in COS-7 cells using a T7 RNA polymerase/vaccinia virus expression system. The open reading frame of hPGHS-2 cloned into vaccinia virus without its natural 5' and 3' untranslated regions directed only low levels of hPGHS-2 enzyme activity in COS-7 cells. High-level hPGHS-2 expression was achieved by appending the 3' untranslated region of hPGHS-1 to the hPGHS-2 open reading frame, with subsequent expression of the hybrid mRNA using vaccinia virus. Enzymatically active recombinant hPGHS-1 and hPGHS-2 were present as glycosylated proteins in the microsomal fraction prepared from infected cells, whereas recombinant hPGHS-1 and hPGHS-2 prepared from the microsomal fraction of cells treated with tunicamycin, an inhibitor of N-linked glycosylation, were enzymatically inactive. The major prostanoid products formed by microsomes from COS-7 cells containing either recombinant hPGHS-1 or hPGHS-2 after incubation with arachidonic acid were prostaglandin D2 and E2, with lower levels of prostaglandin F2 alpha and 6-keto-prostaglandin F1 alpha. A range of potencies were observed for various nonsteroidal anti-inflammatory drugs as inhibitors of prostaglandin E2 synthesis by hPGHS-1 and hPGHS-2. Recombinant hPGHS-1 and hPGHS-2 both produced 15- and 11-hydroxyeicosatetraenoic acid (HETE) from arachidonic acid, with 15-HETE production by hPGHS-2 being stimulated 5-fold by preincubation with aspirin. Chiral phase high performance liquid chromatography analysis showed that aspirin-treated hPGHS-2 produced 15(R)-HETE, with no detectable 15(S)-HETE.
Mol Pharmacol 1994 Feb
PMID:Overexpression of human prostaglandin G/H synthase-1 and -2 by recombinant vaccinia virus: inhibition by nonsteroidal anti-inflammatory drugs and biosynthesis of 15-hydroxyeicosatetraenoic acid. 811 74

Recently, we demonstrated that chronic exposure to hyperoxia causes in vivo airway muscarinic receptor hyperresponsiveness in the developing rat [Am. J. Physiol. 262 (Lung Cell. Mol. Physiol. 6): L263-L269, 1992]. To test whether airway cholinergic hyperresponsiveness might result from intrinsic alterations in smooth muscle contractility, we measured the effect of in vivo hyperoxia on the contractile force elicited by acetylcholine (ACh) of isometrically mounted tracheal rings in vitro. Tracheal rings were obtained from 3-wk-old rats exposed to air or to > 95% O2 for 8 days. Muscarinic responses were determined by measuring the force elicited by exposure to increasing concentrations of ACh. Responses were normalized to the morphometrically determined tracheal smooth muscle cross-sectional area in a plane perpendicular to the axis of force generation. In vivo O2 exposure significantly increased maximal ACh-induced stress generation (response to 10(-3) M ACh: air, 15.92 +/- 1.37 g/mm2; O2, 21.78 +/- 1.52 g/mm2; P = 0.010). The ACh-induced stress generation of cylinders from hyperoxic rats was substantially reduced by both epithelial removal and treatment with the cyclooxygenase inhibitor indomethacin. We conclude that in vivo hyperoxic exposure increases tracheal smooth muscle contractile function in vitro and that epithelium-derived prostaglandin(s) contributes to the observed increase in maximal contractile responsiveness.
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PMID:Exposure of immature rats to hyperoxia increases tracheal smooth muscle stress generation in vitro. 817 85

The effects of one of the main components of fish oil, docosahexaenoic acid (DHA), on prostaglandin (PG) and Ca2+ signaling pathways were examined in intact mucosa and freshly isolated crypt cells of rabbit descending colon. Preincubation of serosal mucosa for 20 min with 1 microM DHA fully suppressed the short-circuit and transepithelial conductance increase induced by serosal addition of 10 microM arachidonic acid (AA). DHA at 1 microM also prevented the Cl- secretion promoted by 10 microM AA, as estimated by unidirectional 36Cl flux measurements (net flux = 0.68 +/- 0.30 versus -1.91 +/- 0.20 microEq/hr/cm2, four experiments, p < 0.001), whereas it did not affect the electrophysiological and ion flux responses to PGE2. Addition of 1 microM DHA to the serosal side of the mucosa also inhibited the PG cascade activation elicited by AA (PG synthesis and second messenger cAMP increase). In vitro assays of colonic cyclooxygenase activity showed that 1 microM DHA inhibited (with a 20-min lag) cyclooxygenase activity to the same extent as 5 microM indomethacin (approximately 82% and 80%, respectively). DHA also affected the Ca2+ signaling pathway; in isolated crypt cells, the cytosolic free Ca2+ concentration ([Ca2+]i) dropped by 49 +/- 7.6% (mean +/- standard error, six experiments) after incubation with 1 microM DHA. The sustained phase of the [Ca2+]i response to 500 nM concentrations of the intracellular Ca(2+)-ATPase inhibitor thapsigargin was also inhibited within 150 sec upon 1 microM DHA addition (141 +/- 5.8 versus 243 +/- 8.2 nM [Ca2+]i mean +/- standard error, eight experiments, p < 0.01). The [Ca2+]i-lowering effect of DHA, which was not achieved by incubation with other free fatty acids, was not prevented by removal of Na+ from the incubation medium (-46 +/- 4.3% versus -47 +/- 3.8%, mean +/- standard error, four experiments), nor it was mediated by cAMP-, protein kinase C-, or calmodulin-dependent mechanisms. The incubation of highly purified basolateral membranes of crypt cells with 1 microM DHA for 1 min produced a 5-fold increase (IC50 = 0.25 microM) in the plasma membrane Ca(2+)-ATPase activity (34.3 +/- 2.73 versus 6.02 +/- 0.50 nmol/mg of protein/min, mean +/- standard error, four experiments, p < 0.0001), thus indicating that the DHA effects on the Ca2+ pathway were mediated mainly by an increase in plasma membrane Ca2+ pump activity. These findings suggest that DHA is a powerful modulator of the cellular response to activation of PG and Ca2+ signaling pathways.
Mol Pharmacol 1994 Apr
PMID:Docosahexaenoic acid and signaling pathways in rabbit colon. 818 54

A mitogen-inducible prostaglandin G/H synthase (PGHS-2 or cyclooxygenase-2) has recently been cloned from chicken and mouse fibroblasts. This protein is distinct from classic prostaglandin G/H synthase (PGHS-1 or cyclooxygenase-1) but has a similar enzymatic activity. Because PGHS-1 is a rate-limiting enzyme in the synthesis of prostaglandins, PGHS-2 may also play an important role in prostaglandin production. To examine whether PGHS-2 is induced by phorbol ester in mast cells, we studied mRNA expression of PGHS-2 and also measured prostaglandin D2 (PGD2) production when canine mastocytoma cells were incubated with phorbol myristate acetate (PMA). PGHS-2 mRNA was induced by PMA, with a maximal induction after 4 h of incubation with 10 nM PMA. There was concentration-dependent production of PGD2 after incubation with PMA. In contrast, PGHS-1 mRNA was expressed in resting cells, and the expression of PGHS-1 mRNA was down-regulated by PMA. Dexamethasone inhibited PMA-induced mRNA expression of PGHS-2 and PGD2 production. Aspirin had no effect on mRNA expression of PGHS-2 but inhibited PGD2 production. In conclusion, PGHS-2 is induced by phorbol ester in canine mast cells. We speculate that PGHS-2 may be important in airway inflammation in which mast cells are activated.
Am J Respir Cell Mol Biol 1993 Nov
PMID:Mitogen-inducible prostaglandin G/H synthase is expressed in canine mastocytoma cells. 821 94

Developmental and regional expression of prostaglandin endoperoxide synthase (PES) transcript was examined in the rat brain and in primary mixed cultures of neurons and glial cells from neonatal brain. Although the PES mRNA level in the brain was much lower than that in peripheral rat tissues such as lung, liver, spleen and kidney, a significant 3.0 kb band was detected in brain samples by Northern blot analysis. During development, PES mRNA was first detectable at postnatal day 7, and increased thereafter toward adulthood. The highest level of 3.0 kb PES mRNA was observed in the olfactory bulb, midbrain, and hypothalamus; and the lowest level in the hippocampus. In primary cultures of neonatal brain cells, the level of 3:0 kb transcript of PES transiently and dramatically increased about 30-fold on the third day after plating. Simultaneously, two cross-hybridizing signals were detected at 4.0 and 7.0 kb. This increase in PES mRNAs was completely inhibited by addition of cytosine-1-beta-D-arabinofuranoside. The induction of PES mRNA was in parallel with the increase in PES protein, as assessed by Western blot analysis. Immunostaining of cultured cells with anti-PES monoclonal antibody revealed that PES protein was induced mainly in neurons but not in glial cells. These results suggest that PES is expressed in the central nervous system at a low concentration under normal conditions, and that the neuronal cells possess an ability to express high levels of PES mRNA and protein.
Brain Res Mol Brain Res 1993 Jul
PMID:Expression of prostaglandin endoperoxide synthase in rat brain. 836 44

Fibroblasts of the pulmonary interstitium are intimately involved in the response of the lung to inflammation as well as in repair of injured tissues. The response of fibroblasts within an inflammatory site appears to be directed, in part, by peptide mediators. Neutral endopeptidase (NEP), a metallopeptidase on the surface membrane of fibroblasts, can inactivate various vasoactive peptides, including kinins and tachykinins. Because lung fibroblasts both secrete cytokines and respond to mediators within the immediate environment, NEP might be regulated by locally generated cytokines. We found that several cytokines, including interleukin-1 alpha (IL-1), tumor necrosis factor-alpha (TNF-alpha), transforming growth factor, interleukin-6, and granulocyte macrophage colony-stimulating factor, enhanced activity of NEP on the surface of intact fibroblasts. In contrast, cultured pleural mesothelial cells had much lower levels of NEP than fibroblasts, and the enzyme was not enhanced by either IL-1 or TNF-alpha. Further studies with IL-1 showed that the effect required at least 6 h of exposure to the cytokine and depended upon final cytokine concentration. Combinations of IL-1 with other cytokines increased NEP activity beyond that in cells treated with individual cytokines, but combinations had less than additive effects. Selected pharmacologic agents indicated that the mechanism involves second messenger pathways. The cytokine effect on NEP was attenuated by indomethacin, an inhibitor of cyclooxygenase, by N-[2-(methylamino) ethyl]-5-isoquinolinesulfonamide dihydrochloride, an inhibitor of protein kinase, and by adenosine 3',5' cyclic monophosphothionate, an analog of cyclic adenosine monophosphate (cAMP) that competitively inhibits the cAMP signal pathway. It was mimicked by dibutyryl cAMP and by forskolin, an activator of adenyl cyclase.(ABSTRACT TRUNCATED AT 250 WORDS)
Am J Respir Cell Mol Biol 1993 Jan
PMID:Cytokines increase neutral endopeptidase activity in lung fibroblasts. 838 Feb 49

Triakontatetraneuropeptide (TTN) is the major processing product of the endogenous anxiogenic peptide ligand of the benzodiazepine receptor, diazepam binding inhibitor. In the present study, we demonstrated by Northern blot analysis that the mRNA levels for tumor necrosis factor-alpha (TNF-alpha), interleukin (IL)-1 beta, granulocyte/macrophage colony-stimulating factor, IL-6, and IL-8 were significantly increased after 4 hr of incubation of human monocytes with lipopolysaccharide (LPS) and TTN (10(-11) M), compared with cells incubated with LPS alone. Exposure of monocytes for 20 hr to LPS and TTN (10(-11) M) also stimulated TNF-alpha, IL-1 beta and granulocyte/macrophage colony-stimulating factor release by 80%, 110%, and 98%, respectively, relative to the response elicited by LPS alone. Smaller stimulatory effects were observed using the prototypic pharmacological peripheral benzodiazepine Ro5-4864 (10(-11) M) (55%, 72%, and 62%, assessed by means of specific enzyme immunoassays). In contrast, TTN and Ro5-4864 did not modulate LPS-induced IL-6 and IL-8 production. Treatment with the cyclooxygenase inhibitor indomethacin increased IL-1 beta and TNF-alpha secretion but not that of IL-6 or IL-8. The observed stimulatory effects of TTN and indomethacin were not additive. Taken together, these findings suggest a common mechanism of action for TTN and indomethacin, involving PG formation. In this respect, TTN inhibited prostaglandin (PG) E2 production by 30%. The fact that the observed modulatory effects correlated with PG levels suggests the existence of a second-messenger pathway associated with the peripheral-type benzodiazepine receptor. These results indicate that human TTN differentially modulates the LPS-induced expression of proinflammatory cytokines, and they further support the concept that this endogenous psychoactive peptide could be involved in physiological control of the inflammatory response.
Mol Pharmacol 1993 Jan
PMID:Modulation of tumor necrosis factor-alpha, interleukin-1 beta, interleukin-6, interleukin-8, and granulocyte/macrophage colony-stimulating factor expression in human monocytes by an endogenous anxiogenic benzodiazepine ligand, triakontatetraneuropeptide: evidence for a role of prostaglandins. 838 Aug 85

Arachidonic acid (AA) stimulated protein phosphorylation in electrically permeabilised islets, most notably of an islet protein of approximate molecular weight 18 kDa. This protein did not appear to be a substrate for cAMP-dependent protein kinase. The AA-induced protein phosphorylation was mediated by unmetabolised AA since the lipoxygenase inhibitor, nordihydroguaretic acid (NDGA), or the cyclooxygenase inhibitor, indomethacin, did not significantly reduce AA-induced phosphorylation. Although saturated fatty acids did not stimulate phosphorylation of islet proteins, a number of cis-unsaturated fatty acids, other than AA, induced 32P incorporation into an 18 kDa protein. However, some fatty acids which stimulated protein phosphorylation had no effect on insulin secretion in experiments where AA clearly stimulated insulin secretion. AA stimulated protein kinase C (PKC) activity extracted from islets but several fatty acids which induced protein phosphorylation had no significant effect on PKC activity in vitro. 50 nM staurosporine had no effect on AA-induced protein phosphorylation but this concentration of staurosporine markedly inhibited PKC activity. 200 nM staurosporine caused complete inhibition of the AA-induced phosphorylation without having any effect on AA-induced insulin secretion. These results suggest that AA and some other fatty acids can promote 32P incorporation into islet proteins, independently of PKC activation, and that AA-induced phosphorylation is not required for insulin secretory responses to AA.
Mol Cell Endocrinol 1993 Feb
PMID:Arachidonic acid-induced insulin secretion from rat islets of Langerhans is not mediated by protein phosphorylation. 838 12

The relationship between the phospholipase-stimulating and immunosuppressive properties of cyclosporin A (CsA) has been investigated in vitro. At concentrations of 0.025 microM and upwards, CsA caused dose-related inhibition of both mitogen- and alloantigen-stimulated uptake of tritiated thymidine by human mononuclear leukocytes (MNL), which was associated with a time- and dose-related enhancement of the generation of lysophosphatidylcholine (LPC), arachidonic acid, and prostaglandin E2 from mitogen-stimulated cells. Arachidonate alone, at concentrations of up to 20 microM, did not affect lymphocyte activation, whereas cyclooxygenase and 5'-lipoxygenase inhibitors failed to protect the cells against the antiproliferative effects of CsA. However, LPC caused dose-related inhibition of MNL proliferation. Moreover, coincubation of MNL with alpha-tocopherol, a lysophospholipid-complexing agent, or with lysophospholipase protected the cells against CsA, as well as against LPC. The Na+,K(+)-ATPase activity of mitogen-activated lymphocytes was also inhibited by CsA, whereas inclusion of alpha-tocopherol or lysophospholipase protected this enzyme. Excessive production of lysophospholipids and consequent inhibition of Na+,K(+)-ATPase during CsA treatment of mitogen- or antigen-activated lymphocytes is a possible biochemical mechanism of the immunosuppressive activity of this agent.
Mol Pharmacol 1993 Sep
PMID:Lysophospholipid-mediated inhibition of Na+,K(+)-adenosine triphosphatase is a possible mechanism of immunosuppressive activity of cyclosporin A. 839 20

We have shown earlier that prostacyclin (PGI2) and its stable analogue: 7-oxo-prostacyclin(7-OXO) may induce a prolonged, late appearing (24-48 h after drug administration), dose dependent protection of the heart from harmful consequences of a subsequent severe ischaemic stress, such as myocardial ischaemia, life-threatening ventricular arrhythmias and early ischaemic morphological changes. In an other study we observed that a similar but shortlived (less than 1 h) cardioprotection, induced by 'preconditioning' brief coronary artery occlusions, is greatly reduced by blockade of the cyclooxygenase pathway, suggesting that prostanoids might play a role in this shortlasting protection. Objective of our present study was to elucidate the importance of some arachidonic acid (AA) metabolites, such as PGI2 and thromboxane A2 (TXA2) in the mechanism of the late appearing, prolonged cardioprotection. Estimation of the metabolites: 6-keto-PGF1 alpha (6-KETO) and thromboxane B2 (TXB2) was made from the perfusate of isolated Langendorff hearts of guinea-pigs pretreated with 50 micrograms/kg 7-OXO, 24 and 48 h before preparation. Pretreatment alone produced a slight, but significant elevation of 6-KETO (from 206 +/- 11 to 284 +/- 19 pg/ml/min after 24 h, and to 261 +/- 18 pg/ml/min after 48 h). No change was seen in TXB2 production. Global ischaemia for 25 min (followed by 25 min reperfusion) markedly increased the release of both AA metabolites; maximal values were observed in the third min of reperfusion (6-KETO from 206 +/- 11 to 1275 +/- 55 pg/ml/min and TXB2 from 29 +/- 4 to 172 +/- 12 pg/ml/min).(ABSTRACT TRUNCATED AT 250 WORDS)
Mol Cell Biochem 1993 Feb 17
PMID:Release of 6-keto-PGF1 alpha and thromboxane B2 in late appearing cardioprotection induced by the stable PGI analogue: 7-OXO-PGI. 845 75


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