Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.49 (reverse transcriptase)
 31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To assess regulation of constitutive prostaglandin G/H synthase (PGHS-1) by interleukin-1 (IL-1) in osteoblastic MC3T3-E1 cells, we compared analysis by competitive reverse transcriptase-polymerase chain reaction (RT-PCR) with Northern blot analysis. Using RT-PCR, IL-1 increased PGHS-1 mRNA levels by 1.84 +/- 0.10 or 2.07 +/- 0.17, depending on the method of calculation. Using Northern blot analysis, the effect of IL-1 on PGHS-1 mRNA levels was more variable, and the variability was increased by normalization of PGHS-1 mRNA levels to the housekeeping genes, beta-actin and glyceraldehyde phosphate dehydrogenase (GAPDH), because their mRNA levels were also regulated by IL-1. We conclude that competitive RT-PCR is a reproducible and accurate method for studying small changes in mRNA levels.
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PMID:Measurement of interleukin-1 stimulated constitutive prostaglandin G/H synthase (cyclooxygenase) mRNA levels in osteoblastic MC3T3-E1 cells using competitive reverse transcriptase polymerase chain reaction. 752 76

To examine the effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on thymic gene expression in vitro, freshly isolated rat thymocytes were incubated with 10 nM TCDD, and reverse transcriptase polymerase chain reaction experiments were performed using primers specific for prostaglandin G/H synthase (PGHS) and glyceraldehyde 3-phosphate dehydrogenase. TCDD selectively repressed PGHS gene expression, with maximal inhibition occurring within 60 min. Gel retardation assays demonstrated that dioxin transiently induced binding of the ubiquitous transcription factor NF kappa B to its cognate response element at early time points. However, TCDD had little ability to induce transformation of the Ah receptor to the xenobiotic responsive element in thymic cytosol. These results indicate that TCDD exerts changes in thymocyte gene expression prior to inducing toxicity.
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PMID:2,3,7,8-Tetrachlorodibenzo-p-dioxin-mediated gene expression in the immature rat thymus. 782 58

A second prostaglandin G/H synthase (PGHS-2), encoded by a gene separate from that for the original PGHS (PGHS-1), has recently been identified. We have shown that PGHS-2 is expressed in cultured mouse calvariae and have compared regulation of PGHS-2 and PGHS-1 messenger RNA (mRNA) levels. PGHS-2 mRNA was not detectable in freshly isolated bones, but was induced during culture and further stimulated by interleukin-1 (IL-1) and PTH. Both factors also increased PGHS-2 protein levels. Changes in medium prostaglandin E2 (PGE2) production correlated with increases in PGHS-2 mRNA levels. However, with IL-1, PGE2 production was increased more than PGHS-2 mRNA levels (treated/control ratio, 3.4 and 1.5, respectively), whereas with PTH there was a closer correspondence (2.0 and 2.1). Cortisol reduced PTH-stimulated PGE2 production (treated/control ratio decreased from 3.1 to 0.2) more than PGHS-2 mRNA levels (2.8 to 0.8). In the presence of exogenous arachidonic acid, changes in PGHS-2 mRNA levels with IL-1, PTH, and cortisol correlated closely with changes in PGE2 production. PGE2 itself increased PGHS-2 mRNA, and nonsteroidal antiinflammatory drugs decreased PGHS-2 mRNA levels by 80%. In contrast, PGHS-1 mRNA was expressed constitutively and was not affected by IL-1, PTH, or cortisol when measured by competitive reverse transcriptase-polymerase chain reaction. We conclude that regulation of PGE2 production is predominantly through PGHS-2, rather than PGHS-1; that IL-1 and cortisol may also regulate arachidonic acid release; and that PGE2 may amplify its own production through stimulation of PGHS-2.
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PMID:Regulation of the two prostaglandin G/H synthases by parathyroid hormone, interleukin-1, cortisol, and prostaglandin E2 in cultured neonatal mouse calvariae. 807 Mar 58

The rate-limiting step in the formation of prostanoids is the conversion of arachidonic acid to prostaglandin H2 by cyclooxygenase, also known as prostaglandin G/H synthase/cyclooxygenase. Two forms of cyclooxygenase have been characterized: a ubiquitously expressed form (COX-1) and a recently described second form (COX-2) inducible by various factors including mitogens, hormones, serum and cytokines. Here we quantitate by the reverse transcriptase-polymerase chain reaction (RT-PCR) the expression of COX-1 and COX-2 mRNA in human tissues including lung, uterus, testis, brain, pancreas, kidney, liver, thymus, prostate, mammary gland, stomach and small intestine. All tissues examined contained both COX-1 and COX-2 mRNA and could be grouped according to the level of COX mRNA expression. The highest levels of COX mRNAs were detected in the prostate where approximately equal levels of COX-1 and COX-2 transcripts were present. In the lung high levels of COX-2 were observed whereas COX-1 mRNA levels were about 2-fold lower. An intermediate level of expression of both COX-1 and COX-2 mRNA was observed in the mammary gland, stomach, small intestine, and uterus. The lowest levels of COX-1 and COX-2 mRNA were observed in the testis, pancreas, kidney, liver, thymus, and brain.
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PMID:Expression of mRNA for cyclooxygenase-1 and cyclooxygenase-2 in human tissues. 836 85

The ability of prostaglandins to inhibit collagen synthesis and induce prostaglandin G/H synthase in bone cells appears to be mediated by the prostaglandin F2 alpha receptor (FPR). We have identified FPR mRNA in the osteoblastic cell lines, Py1a from rats and MC3T3-E1 from mice, as well as in the stem cell cultures, MN-7 and mouse marrow, using reverse transcriptase-polymerase chain reaction technology (RT-PCR). Expression of FPR mRNA was increased in Pyla, MN-7 and marrow cells with prolonged culture or dexamethasone treatment and decreased after treatment with fluprostenol, a selective FPR agonist.
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PMID:Expression and regulation of prostaglandin F receptor mRNA in rodent osteoblastic cells. 883 44

The human osteosarcoma 143.98.2 cell line was found to express high levels of prostaglandin synthase-2 (PGHS-2) without detectable levels of prostaglandin synthase-1 (PGHS-1) as measured by reverse transcriptase-polymerase chain reaction (RT-PCR) and immunoblot analysis. Maximal levels of PGHS-2 induction were attained when the cells were grown beyond confluence. The osteosarcoma cells also secrete IL-1 alpha, IL-1 beta and TNF alpha in the culture medium. PGHS-2 expression was inducible by the exogenous addition of these cytokines as well as conditioned media from auto-induced cultures and inhibitable by treatment with dexamethasone. In contrast, undifferentiated U937 cells selectively express PGHS-1 as analyzed by RT-PCR and Western blotting. The effects of non-steroidal anti-inflammatory drugs (NSAIDs) on the cellular PGE2 production mediated by each isoform of human PGHS were determined using osteosarcoma and undifferentiated U937 cells. When cells were preincubated with inhibitors to allow time-dependent inhibition prior to arachidonic acid stimulation, NS-398, CGP 28238, L-745,337, SC-58125 all behaved as potent (IC50 = 1-30 nM) and selective inhibitors of PGHS-2, in contrast to indomethacin, flurbiprofen or diclofenac which are potent inhibitors of enzymes. DuP-697 and sulindac sulfide were also potent inhibitors of PGHS-2 but both compounds inhibited cellular PGHS-1 activity at higher doses (IC50 = 0.2-0.4 microM). Time-dependent inhibition of PGE2 production in osteosarcoma cells was observed for indomethacin, diclofenac and etodolac. The synthesis of PGE2 by U937 cells was strongly dependent on exogenous arachidonic acid (100-fold stimulation) whereas confluent osteosarcoma cells also produced PGE2 without exogenous stimulus (7-fold stimulation by arachidonic acid). Osteosarcoma cells grown beyond confluence released more PGE2 from endogenous substrate than arachidonic acid stimulated undifferentiated U937 cells. These results indicate that osteosarcoma cells selectively express PGHS-2 with an autocrine regulation and effective utilization of endogenous arachidonic acid for PGE2 synthesis.
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PMID:Characterization of autocrine inducible prostaglandin H synthase-2 (PGHS-2) in human osteosarcoma cells. 908 44

Prostaglandin D2 (PGD2) synthesis in activated mast cells occurs in two phases, an early phase that is dependent on prostaglandin synthase 1 and a delayed phase that is dependent on activation-induced prostaglandin synthase 2 gene expression. Early phase PGD2 synthesis in activated mast cells also requires the activity of a secretory phospholipase A2 (PLA2). It has been thought that the secretory PLA2 expressed in mast cells is group IIa PLA2, encoded by the Pla2 g2a gene. However, activated bone marrow-derived mast cells prepared from Pla2 g2a+/+ mice and mast cells prepared from mice with a mutation in the Pla2 g2a gene both demonstrate early phase PGD2 synthesis. Moreover, mast cells from both murine strains secrete PLA2 activity following activation. Northern and reverse transcriptase/polymerase chain reaction analyses demonstrate that mast cells from Pla2 g2a+/+ and Pla2 g2a-/- mice do not express group IIa PLA2 message. Instead, Northern and reverse transcriptase/polymerase chain reaction analyses demonstrate that both Pla2 g2a+/+ and Pla2 g2a-/- mast cells express mRNA for group V PLA2, encoded by the Pla2gV gene. An antisense oligonucleotide directed against group V PLA2 is also able to inhibit both the early phase of PGD2 production and the secretion of PLA2 activity by activated mast cells. Our data suggest that (i) group IIa PLA2 does not play a significant role in murine mast cell prostaglandin synthesis, (ii) group V PLA2 mediates early mast cell PGD2 production and transcellular PGE2 production in murine mast cells, and (iii) much of the data, based on studies with chemical inhibitors and antibodies, suggesting that group IIa PLA2 is responsible for arachidonic acid mobilization needs to be reevaluated.
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PMID:Analysis of the secretory phospholipase A2 that mediates prostaglandin production in mast cells. 915 7