Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.7.7.6 (RNA polymerase)
34,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. Induction of nitric oxide synthase (iNOS) results in overproduction of nitric oxide (NO), which may be a principal cause of the massive vasodilatation and hypotension observed in septic shock. Since NO-induced vasorelaxation is mediated via the soluble isoform of guanylate cyclase (sGC), the regulation of sGC activity during shock is of obvious importance, but yet poorly understood. The aim of the present study was to investigate the activation of sGC by sodium nitroprusside (SNP) before and after exposure of rat aortic smooth muscle cells to endotoxin (LPS) or interleukin-1 beta (IL-1 beta). 2. Exposure of rat aortic smooth muscle cells to SNP (10 microM) elicited up to 200 fold increases in cyclic GMP. This effect was attenuated by 30-70% in IL-1 beta- or LPS-pretreated cells, in a pretreatment time-and IL-1 beta- or LPS-concentration-dependent manner. When, however, cells were exposed to IL-1 beta or LPS and then stimulated with the particulate guanylate cyclase activator, atriopeptin II, no reduction in cyclic GMP accumulation was observed. 3. Pretreatment of rats with LPS (5 mg kg-1, i.v.) for 6 h led to a decrease in aortic ring SNP-induced cyclic GMP accumulation. 4. The IL-1 beta-induced reduction in SNP-stimulated cyclic GMP accumulation in cultured cells was dependent on NO production, as arginine depletion abolished the downregulation of cyclic GMP accumulation in response to SNP. 5. Reverse-transcriptase-polymerase chain reaction analysis revealed that the ratio of steady state mRNA for the alpha, subunit of sGC to glyceraldehyde phosphate dehydrogenase was decreased in LPS- or IL-1 beta-treated cells, as compared to vehicle-treated cells. 6. Protein levels of the alpha 1 sGC subunit remained unaltered upon exposure to LPS or IL-1 beta, suggesting that the early decreased cyclic GMP accumulation in IL-1 beta- or LPS-pretreated cells was probably due to reduced sGC activation. Thus, the observed decreased responsiveness of sGC to NO stimulation following cytokine or LPS challenge may represent an important homeostatic mechanism to offset the extensive vasodilatation seen in sepsis.
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PMID:Downregulation of nitrovasodilator-induced cyclic GMP accumulation in cells exposed to endotoxin or interleukin-1 beta. 883 57

Recent studies suggest that interleukin-6 (IL-6) is produced in the intestinal mucosa during sepsis and endotoxemia and that the enterocyte may be a source of IL-6 in these conditions. The regulation of IL-6 production in the enterocyte is not fully understood. We tested the hypothesis that IL-6 production in the enterocyte is regulated by proinflammatory cytokines. This was done by treating cultured Caco-2 cells, a transformed human intestinal epithelial cell line, with different concentrations of tumor necrosis factor-alpha (TNF-alpha), IL-1 beta, IL-6 or interferon-gamma (IFN-gamma). IL-6 production by the Caco-2 cells was determined by ELISA. The expression of IL-6 mRNA was determined by reverse-transcriptase polymerase chain reaction. IL-6 was not produced in unstimulated Caco-2 cells. Treatment of the Caco-2 cells with IL-1 beta resulted in a dose- and time-dependent stimulation of IL-6 production with a maximal effect noted at an IL-1 beta concentration of .5 ng/mL at 24 h. IFN-gamma alone did not stimulate IL-6 production but potentiated the effect of IL-1 beta in a synergistic fashion. Treatment of the Caco-2 cells with IL-1 beta induced expression of IL-6 mRNA with a response noticed after 30 min. TNF-alpha and IL-6 did not influence the production of IL-6 in the Caco-2 cells. The results suggest that enterocyte IL-6 production is stimulated by IL-1 beta and that this effect is potentiated by IFN-gamma. The regulation of IL-6 production in the enterocyte may be specific for IL-1 beta, since neither TNF nor IL-6 stimulated IL-6 production.
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PMID:Interleukin-1 beta and interferon-gamma regulate interleukin-6 production in cultured human intestinal epithelial cells. 932 25

Interleukin-1 (IL-1) is a proinflammatory cytokine produced by blood-borne and resident inflammatory lung tissue involved in the thrombotic occlusion of the pulmonary microcirculation and the increase of the vascular permeability following a wide variety of injuries and sepsis. The locally accentuated, organ-related activation of this cytokine seems to be responsible for the development of acute lung injury. The present study was conducted to determine if IL-1beta was produced in an ischemia-reperfusion (I/R) rat model subjected to lung injury. We measured sequential perfusate levels of IL-1beta by ELISA and we measured IL-1 gene expression in the rat lung tissue by a reverse-transcriptase polymerase chain reaction method. Little IL-1beta gene expression was observed in normal rat lung tissue. Perfusate IL-1beta slightly increased 2 h after induced ischemia and 3 h after reperfusion. IL-1beta gene expression rapidly increased as early as 30 min after ischemia and continued to increase for up to 120 min. IL-1beta gene expression was dramatically upregulated during reperfusion after cessation of ischemia, reached a peak at 1 h, and then gradually decreased (2 to 3 h) to near baseline levels. During ischemia, the increased IL-1 gene expression was not significantly different between the ventral and dorsal sites of the lung. However, IL-1 gene expression markedly increased on the dorsal part (the dependent site for a rat in a supine position) after reperfusion. From these results, it appears that IL-1 may have an important role in I/R lung injury.
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PMID:Interleukin-1 in ischemia-reperfusion acute lung injury. 935 26

The effect of sepsis on the ubiquitously expressed ATP-sensitive potassium (uK(ATP)-1) channel expression was measured in Sprague-Dawley rat diaphragms. Rats were treated with either 0.5 ml saline or 20 mg/Kg E. coli lipopolysaccharides and sacrificed at 3, 6, 12, 24, or 48 h later. Reverse transcriptase-polymerase chain reaction (RT-PCR) analysis showed that channel mRNA expression was increased at 3 h and continued to rise up to 48 h. Western blotting analysis showed a approximately 9-fold increase in channel protein expression 24 h after sepsis. Our results demonstrate that sepsis upregulates the uK(ATP)-1 channel.
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PMID:Induction of the ATP-sensitive potassium (uK(ATP)-1) channel by endotoxemia. 1084 76

Clinical and experimental studies have implicated high circulating levels of the cytokine tumour necrosis factor-alpha (TNF-alpha) in the pathogenesis of insulin resistance, not only in obesity and diabetes, but also in clinical conditions associated with cachexia and sepsis. TNF-alpha impairs insulin-mediated glucose uptake in adipocytes, but because of lipolytic effects the interpretation of clinical studies and the extent to which TNF-alpha affects muscle insulin sensitivity are unclear. In addition, protein kinase C (PKC) has recently been implicated in the mechanism of TNF-alpha-induced insulin resistance. The present study investigated the effects of TNF-alpha and a PKC inhibitor (RO-318220) on basal and insulin-stimulated 2-[(3)H]deoxyglucose uptake in cultured L6 myoblasts. Reverse transcriptase-PCR analysis confirmed that L6 myoblasts express TNF-alpha receptors I and II (p60 and p80). Dose-response curves for glucose uptake were fitted to a quadratic function to derive C(I-150) values (concentration of insulin required to increase glucose uptake by 50%). Incubation with TNF-alpha at 1 or 10 ng/ml for 24 h had no significant effect on basal glucose uptake, insulin sensitivity or maximal insulin responsiveness. C(I-150) values (means+/-S.E.M.) were as follows: basal, 91.2+/-13 nM; 1 ng/ml TNF-alpha, 102+/-12 nM; and basal, 70.8+/-13 nM; 10 ng/ml TNF-alpha, 43.7+/-40 nM. PKC inhibition markedly attenuated glucose uptake, but there was no difference in insulin sensitivity with RO-318220 alone compared with RO-318220+TNF-alpha. In conclusion, although increased TNF-alpha expression and plasma concentrations have been implicated in the pathogenesis of insulin resistance in various clinical states, there is no evidence that TNF-alpha impairs insulin-stimulated glucose uptake in a skeletal-muscle-derived cell line.
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PMID:Effects of tumour necrosis factor-alpha and inhibition of protein kinase C on glucose uptake in L6 myoblasts. 1099 95

Streptococcus agalactiae (group B streptococcus, GBS) is the major pathogen of neonatal sepsis. In some newborns, GBS sepsis may have a severe course, including septic shock with a high mortality rate, whereas other newborns are colonized with GBS on their surfaces without any clinical signs of bacterial infection. The reason for this discrepancy is far from clear. We sought, in this study, to compare cytokine expression in cord blood mononuclear cells after stimulation with GBS strains isolated from newborns with sepsis, and strains isolated from newborns without any symptoms of invasive infection. Cord blood mononuclear cells were incubated with either heat-killed bacteria of different strains or lipopolysaccharide, respectively. After 6 and 24 h, cells were harvested and cytokine mRNA-expression was analyzed by reverse-transcriptase PCR. Likewise, supernatants were tested for IL-6 and tumor necrosis factor-alpha concentrations by enzyme immunoassay. When comparing IL-6 and tumor necrosis factor-alpha secretion, there were significantly higher IL-6 levels after stimulation with sepsis than with colonizing isolates. Likewise, mRNA expression of IL-6, IL-1 beta, and IL-12p40 was significantly higher after stimulation with sepsis isolates. This was also true when normalizing to cytokine expression after stimulation with lipopolysaccharide. These findings indicate that the different clinical pictures in response to GBS, either septic infection or colonization, might reflect strain-specific properties. If the respective characteristics can be defined, it might become possible to distinguish by molecular methods potentially "dangerous" from "harmless" strains. Moreover, our findings underline the essential role of these cytokines in the pathogenesis of neonatal GBS sepsis.
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PMID:Different cytokine expression in cord blood mononuclear cells after stimulation with neonatal sepsis or colonizing strains of Streptococcus agalactiae. 1132 54

Group B streptococci (GBS) remain the most significant bacterial pathogen causing neonatal sepsis, pneumonia, and meningitis in the United States despite the chemoprophylaxis strategies for preventing infection recommended by the Centers for Disease Control and Prevention. Using signature-tagged transposon mutagenesis to screen for novel virulence factors, we identified the rpoE gene as essential for development of sepsis in a neonatal rat model of GBS infection. An rpoE allelic replacement mutant displayed attenuated virulence in the sepsis model of infection identical to that of the transposon mutant, confirming linkage of the phenotype to the mutation in rpoE. The rpoE mutants also displayed increased sensitivity to killing in whole-blood bactericidal assays, which may explain the attenuated virulence. The mutants were otherwise phenotypically identical to the wild-type strain, including growth rate in plasma, indicating that a growth defect is not responsible for the attenuated virulence. rpoE is found only in gram-positive bacterial species and encodes the delta peptide, a subunit of RNA polymerase. Previous in vitro studies in other bacteria suggest that the delta peptide plays a role in maintaining transcriptional fidelity by blocking RNA polymerase binding at all but the strongest promoters, thereby inhibiting initiation of transcription. Despite the availability of rpoE mutants for several gram-positive bacterial species, a role for the peptide in vivo has not been defined, though it has been postulated that the delta peptide may be important for long-term survival in vitro or during growth phase transitions. Our data represent the first report of a phenotype relevant to virulence for rpoE mutants.
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PMID:The Delta subunit of RNA polymerase is required for virulence of Streptococcus agalactiae. 1281 89

The purpose of this study was to evaluate the kinetic changes and the localization of high-mobility group box 1 protein (HMGB1) and to observe the effect of heat shock response (HSR) on the expression and release of HMGB1 in lipopolysaccharide (LPS)-activated murine macrophage-like RAW 264.7 cells. Reverse transcriptase (RT)-PCR and Western blot were used to examine HMGB1 expression after LPS treatment. The intracellular localization of HMGB1 in normal or LPS-activated cells was investigated by immunocytochemical analysis and HMGB1 released from cultured macrophages by Western blot. HSR was performed by incubating RAW 264.7 cells at 42.5 degrees C for 1 h then recovery at 37 degrees C for 12 h. The effect of HSR on expression and release of HMGB1 was observed. The results showed that a decrease of HMGB1 mRNA expression was observed at 18 h after LPS (500 ng/mL) treatment, although the total intracellular HMGB1 protein levels were not affected. A visible translocation of HMGB1 from the nuclear to the cytoplasm was observed at 20 h after stimulation with LPS (500 ng/mL). Furthermore, HMGB1 was released into the medium by LPS-activated RAW 264.7 cells in a time- and dose-dependent manner. Heat shock pretreatment significantly inhibited LPS-induced release of HMGB1 and the translocation of HMGB1 from the nucleus to the cytoplasm in RAW 264.7 cells. These findings suggest that the release of HMGB1 by LPS-activated macrophages is a late event in the pathogenesis of sepsis and that HSR could inhibit the release and translocation of HMGB1 induced by LPS.
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PMID:Heat shock response inhibits release of high mobility group box 1 protein induced by endotoxin in murine macrophages. 1583 9

Group B streptococcus (GBS) remains a major cause of morbidity and mortality among newborn children. The bacterium is a commensal organism colonizing the rectum and the gastrointestinal and urogenital tracts of adults, but it can be transmitted to neonates by an ascending infection of the maternal genital tract or during parturition. We previously reported that a transposon insertion disrupting rpoE resulted in the decreased survival of the mutant in the neonatal rat sepsis model of GBS infection. rpoE encodes the delta protein, a subunit of RNA polymerase (RNAP) that has been characterized in Bacillus species. In this study, we confirm the association of the delta protein with purified GBS RNAP and show that it is expressed in strains representing all nine serotypes. Flow cytometric analysis of a reporter strain containing a transcriptional fusion of the rpoE promoter to gfp revealed that, in vitro, this gene is continuously expressed. Analysis of delta expression in the transposon mutant by quantitative Western blotting revealed a 10-fold reduction in relative abundance (which was linked to the attenuation in virulence that was observed for this mutant) compared to that for the wild-type strain. These data suggest that a minimum intracellular concentration of delta is necessary for this organism to cause disease.
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PMID:Abundance of the delta subunit of RNA polymerase is linked to the virulence of Streptococcus agalactiae. 1651 39

Aberrant regulation of innate immune responses and uncontrolled cytokine bursts are hallmarks of sepsis and endotoxemia. Activation of the nuclear liver X receptor (LXR) was recently demonstrated to suppress inflammatory genes. Our aim was to investigate the expression of LXR in human monocytes under normal and endotoxemic conditions and to study the influence of LXR activation on endotoxin-induced cytokine synthesis and release. Adherent human monocytes or whole blood were pretreated with a synthetic LXR agonist (3-{3-[(2-chloro-3-trifluoromethyl-benzyl)-(2,2-diphenyl-ethyl)-amino]-propoxy}-phenyl)-acetic acid) and subsequently challenged with LPS (from Escherichia coli) or peptidoglycan (from Staphylococcus aureus). Cytokine release was assessed by a Multiplex antibody bead kit, and cytokine mRNA levels were measured by real-time reverse-transcriptase-polymerase chain reaction. We found that LXRalpha mRNA was up-regulated in CD14+ monocytes in LPS-challenged blood, whereas LXRbeta mRNA was not altered. Addition of 3-{3-[(2-chloro-3-trifluoromethyl-benzyl)-(2,2-diphenyl-ethyl)-amino]-propoxy}-phenyl)-acetic acid to monocytes suppressed the LPS-induced release of IL-1beta, IL-6, IL-8, IL-10, IL-12p40, TMF-alpha, macrophage inflammatory protein 1alpha, macrophage inflammatory protein 1beta, and monocyte chemoattractant protein 1 in a concentration-dependent manner. Surprisingly, an accompanying decrease in cytokine mRNA accumulation was not observed. The suppressed cytokine release could not be explained by a diminished transport of mRNA out of the nucleus or a decreased secretion of cytokines. We propose that LXR is a key regulator of cytokine release in LPS-challenged human monocytes, possibly by interfering with translational events.
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PMID:Liver X receptor is a key regulator of cytokine release in human monocytes. 1772 34


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