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

Human leukemia (HL) 60 cells were differentiated by dimethylsulfoxide (DMSO) treatment to granulocyte-like cells, leukotriene (LT) synthesizing activity of which was increased in response to the differentiation of the cells. Four synthesizing enzymes, cytosolic phospholipase A2 (cPLA2), 5-lipoxygenase (5-LO), LTA4 hydrolase and LTC4 synthase, and an enzyme associated protein, 5-lipoxygenase activating protein (FLAP) are involved in the generation of LTC4 and LTB4. We examined the expression of messenger RNA (mRNA) for these LT synthesizing enzymes and an associated protein in DMSO differentiated HL-60 cells by reverse transcriptase polymerase chain reaction (RT-PCR). The production of LTC4 and LTB4, measured by radioimmunoassay (RIA), was increased after the incubation with DMSO for more than 3 days. Messenger RNA abundance for 5-LO, LTC4 synthase and LTA4 hydrolase was increased, that for FLAP was stable, but that for cPLA2 was decreased. These results indicate that DMSO induced increase of LT synthesis is associated with the increase of mRNA expression of 5-LO, LTC4 synthase and LTA4 hydrolase, although the precise regulatory mechanisms of the increased mRNA expression are not determined. We also investigated an action of dexamethasone (DEX) on DMSO-induced enhancement of LT synthesis. DEX suppressed DMSO induced increase of LTC4 synthesis, but rather enhanced DMSO induced LTB4 production. The DEX attenuated the DMSO-induced increase of mRNA expression for LTC4 synthase, but showed no effect on that for LTA4 hydrolase. The inhibition of LTC4 synthesis is associated with the suppression of mRNA expression for LTC4 synthase. However, increased LTB4 synthesis by DEX is regulated by the mechanisms which are independent from mRNA level of LTA4 hydrolase.
 ...
PMID:Effect of dexamethasone on leukotriene synthesis in DMSO-stimulated HL-60 cells. 1010 84

Leukotrienes (LTs) are recognized to be important mediators in asthma. Recent studies revealed that LT synthesis is controlled by the regulation of LT-synthesizing enzymes. We determined the synthesis of LTB4 and LTC4 by specific radioimmunoassay, and the messenger RNA (mRNA) expression of LT-synthesizing enzymes by reverse transcriptase polymerase chain reaction in peripheral polymorphonuclear leukocytes, which were obtained from controls and asthmatic children. The synthesis of LTB4 and LTC4, and the mRNA expression of 5-lipoxygenase, LTA4 hydrolase, and LTC4 synthase were enhanced in the patients. The mRNA expression of LT-synthesizing enzymes was up-regulated, resulting in increased LT synthesis, which may play an important role in the pathogenesis of childhood asthma.
 ...
PMID:Leukotriene synthesis is increased by transcriptional up-regulation of 5-lipoxygenase, leukotriene A4 hydrolase, and leukotriene C4 synthase in asthmatic children. 1276 16