Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P43026 (lipopolysaccharide)
 62,215 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The met proto-oncogene encodes the cell surface receptor for hepatocyte growth factor (HGF) and transmits its multifunctional signals such as regulation of cell proliferation, motility, and morphogenesis. These pleiotropic actions attributable to HGF are mainly reported on cells of epithelial derivation which express the Met receptor. The HGF gene, on the other hand, is expressed in mesenchymally derived cells including peripheral blood leukocytes. Recently, we reported that Met receptor gene expression in epithelial cells is induced by inflammatory cytokines; currently, however, little is known concerning Met gene expression in mesenchymal cells. In the present study, we have explored the role of Met expression during monocyte-macrophage differentiation using THP-1 cells, a monocytic cell line, and monocytes freshly isolated from normal human peripheral blood. We have found that untreated monocytes do not express Met mRNA and protein. Upon incubation with differentiation inducers such as 12-O-tetradecanoylphorbol-13-acetate, lipopolysaccharide, a combination of interleukin (IL) 6 plus tumor necrosis factor (TNF) alpha, or IFN-gamma plus TNF-alpha, a pronounced increase in the amounts of Met mRNA and protein are seen in THP-1 cells. The expression of Met appears to correlate with the onset of differentiation of monocytes as noted by changes in cell morphology and adherence to culture plates, and the increased accumulation of Met protein was observed only in cells that differentiated and adhered to the culture dish. Moreover, Met was found to be phosphorylated on tyrosine residues, indicating that the receptor is potentially involved in signal transduction events. Addition of exogenous HGF to the activated cells resulted in the suppression of cell proliferation and an increase in cell motility. Reverse transcription-PCR and Western blot analyses revealed that untreated THP-1 cells contain HGF transcript and protein, and that HGF expression is inducible by addition of the differentiation agents such as 12-O-tetradecanoylphorbol-13 acetate or IL-6 plus TNF-alpha. Immune serum that is specific for neutralizing HGF activity markedly inhibited monocyte differentiation (50% reduction in cell attachment and process formation) induced by IL-6 and TNF-alpha. Moreover, we also found that the mRNA for Ron, which encodes a tyrosine kinase receptor for HGF-like protein (also known as macrophage-stimulating protein), is induced in THP-1 cells during the course of their differentiation to macrophages by IFN-gamma plus TNF-alpha. These findings indicate that the HGF and Met families may indeed be physiological regulators of monocyte-macrophage differentiation/maturation.
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PMID:Induction of met proto-oncogene (hepatocyte growth factor receptor) expression during human monocyte-macrophage differentiation. 878 Aug 95

In vitro pharmacologic measures of drug specificity are well established, i.e. drug interaction with a specific target such as an enzyme, receptor, or ion channel. However, in vitro measures of drug selectivity, defined as effects on secondary targets, are lacking. Two-dimensional gel electrophoresis (2-D gel) was examined as a measure of drug selectivity by comparing the effects of three drugs, tenidap, piroxicam, and dexamethasone, on the synthesis of intracellular proteins in lipopolysaccharide (LPS)-stimulated murine macrophages. A set of 902 35S-methionine-labeled proteins were separated consistently, identified by their coordinates of apparent isoelectric point and molecular weight, and quantified. LPS altered the concentrations of 45 proteins. Tenidap, at 10 microM, affected a total of five proteins (suppressed three; stimulated two), whereas piroxicam, at 10 microM, suppressed two proteins. Dexamethasone at 0.01 microM suppressed eight proteins and stimulated one. Thus, none of the drugs reversed the LPS-induced changes. Two of the eight proteins suppressed by dexamethasone were also suppressed by tenidap and were identified as proIL-1 alpha and proIL-1 beta. Since the subset of affected proteins provided a unique protein "fingerprint" for each drug, the three drugs were mechanistically differentiated by 2-D gel analysis. Compared to LPS (5% affected proteins), all three drugs were selective (< or = 1% affected) with piroxicam > tenidap > dexamethasone. With identification of affected proteins, this technique can provide a useful in vitro assessment of drug selectivity.
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PMID:Determining selectivity of drugs by quantitative two-dimensional gel analysis. A study of tenidap, piroxicam, and dexamethasone. 878 11

Microglial cells respond to most pathological events by rapid transformation from a quiescent to an activated phenotype characterized by increased cytotoxicity and motile activity. To investigate the regulation of microglial motility by different inflammatory mediators, we studied cultured murine microglia by time-lapse video microscopy and a computer-based motility assay. Microglial cells exhibited a high resting motility. The acute application of complement 5a (C5a) immediately induced intense ruffling of microglial membranes followed by lamellipodia extension within few seconds, while formyl-Met-Leu-Phe-OH, bacterial endotoxin (lipopolysaccharide) or inflammatory cytokines did not increase motility. This process was accompanied by a rapid rearrangement of the actin cytoskeleton as demonstrated by labelling with fluorescein isothiocyanate-phalloidin and could be inhibited by cytochalasin B. A GTP-binding protein was involved in the signal cascade, since pertussis toxin inhibited motility and actin assembly in response to C5a. Chemotactic migration in a gradient of C5a was also completely blocked by pertussis toxin and cytochalasin B. The C5a-induced motility reaction was accompanied by an increase in intracellular calcium ([Ca2+]i) as measured by a Fluo-3 based imaging system. Ca2+ transients were, however, not a prerequisite for triggering the increase in motility; motility could be repeatedly evoked by C5a in nominally Ca(2+)-free solution, while Ca2+ signals occurred only upon the first stimulation. Moreover, conditions mimicking intracellular Ca2+ transients, like incubation with thapsigargin or Ca2+ ionophore A23187, were not able to induce any motility reaction, suggesting that Ca2+ transients are not necessary for, but are associated with, microglial motility. Motile activity was shown to be restricted to a defined concentration range of [Ca2+]i as revealed by lowering [Ca2+]i with BAPTA-AM or increasing [Ca2+]i with A23187. Since complement factors are released at pathological sites, this signal cascade could serve to increase motility and to direct microglial cells to the lesioned or damaged area by means of a G-protein-dependent pathway and via the rearrangement of the actin cytoskeleton.
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PMID:Complement 5a controls motility of murine microglial cells in vitro via activation of an inhibitory G-protein and the rearrangement of the actin cytoskeleton. 880 27

While non-stimulated primary human monocytes exhibit very low levels of tumor necrosis factor (TNF)-alpha mRNA, direct binding of the staphylococcal exotoxin toxic shock syndrome toxin-1 (TSST-1) to major histocompatibility complex (MHC) class II molecules results in a fast (peak 1 h after stimulation), transient induction (sevenfold) of TNF-alpha mRNA. This induction correlates with a fourfold increase in transcription rates of the TNF-alpha gene, as detected by run-on assays, and does not require de novo protein synthesis. Mapping of DNase-I hypersensitive sites (DHS) discloses two constitutive DHS, one located far upstream (within the TNF-beta promoter) and the other centered at -39 +/- 40 bp relative to the major TNF-alpha transcription start site, suggesting that the TNF-alpha gene was transcriptionally competent even prior to MHC class II engagement. Furthermore, stimulation of human monocytes with either TSST-1 or lipopolysaccharide increases the translational efficiency of TNF-alpha mRNA, as shown by a shift in the distribution of this mRNA species in polysome gradients and the translation rates of TNF-alpha measured by immunoprecipitation from cells pulsed with [35S] methionine. The increase in translation efficiency of TNF-alpha mRNA is independent of the half-life of TNF-alpha transcripts, which under the conditions used is unchanged. Taken together, our data indicate that TNF-alpha expression is tightly regulated by MHC class II ligands, both at the transcriptional and translational levels.
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PMID:Transcriptional and translational control of TNF-alpha gene expression in human monocytes by major histocompatibility complex class II ligands. 889 55

B and T cells present in the spleen and other sites of the immune system play a crucial role in the protection of individuals by mounting a specific primary and secondary immune response. Disturbances in their signaling and functioning could lead to a deterioration of the defense mechanisms and thereby lead to infections, pathologies or diseases. In this work, we studied the effects of stress on the protein synthesis and metabolism of mouse splenocytes. The study was done by radiolabeling the entire mouse with 35S-methionine (in vivo procedure) or by culturing spleen cells under various conditions of stimulation in the presence of 35S-methionine (in vitro labeling). The stimulus was lipopolysaccharide (LPS), LPS + interleukin-4 (IL-4) and concanavalin A (on A). Samples from immobilization stressed and control animals were studied in parallel. The results showed minimum alterations due to stress on B cells, though a small decrease in proliferative capacity was observed. In contrast, T cells are profoundly affected by stress. More than 100 new proteins are expressed on 2D-gel patterns of T cells from stressed animals as compared with controls, some of which could be implicated in different signaling, or could have appeared because of an alteration in a pathway of synthesis, or even as a consequence of a change in the composition of T cell populations induced by stress.
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PMID:Lymphocyte protein synthesis: evidence that murine T cells are more affected by stress than B cells. 890 5

The kinetics of IL-8, tumour necrosis factor-alpha (TNF-alpha) and IL-1 beta release by PMN adhered to fibronectin, laminin or plastic for 24 h in response to continuous stimulation with lipopolysaccharide (LPS; 50 ng/ml), N-formyl-Met-Leu-Phe (fMLP; 100 mM), or phorbol myristate acetate (PMA; 10 ng/ml), was investigated under altered oxygen tension conditions. Cell supernatants were sampled for cytokine content every 6 h and measured by ELISA. IL-8 was the most abundant cytokine, produced in a range of up to 5.4 ng/ml; TNF-alpha and IL-1 beta were produced in a range of up to 1 ng/ml. During normoxia, LPS was the most potent stimulus, inducing the release of each cytokine, while fMLP showed a less pronounced effect on IL-8 and IL-1 beta production and markedly inhibited TNF-alpha production. PMA markedly suppressed IL-8 and IL-1 beta release and failed to induce any release of TNF-alpha. Hypoxia had an overall inhibitory effect on cytokine release except for PMA-induced IL-1 beta release, and hypoxia/reoxygenation had a significant up-regulating effect except for a further inhibition of fMLP-induced release of TNF-alpha. Integrinmatrix protein ligation differentiated both spontaneous and externally induced cytokine release and its sensitivity to alteration in oxygen tension. Thus the process of PMN elaboration of inflammatory cytokines is controlled on multiple levels of signal transduction, differentiated by integrin-extracellular matrix interactions, and is sensitive to alterations in microenvironmental oxygen tension.
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PMID:Polymorphonuclear leucocyte (PMN)-derived inflammatory cytokines--regulation by oxygen tension and extracellular matrix. 897 28

Mutagenesis with the transposon Tn916 was used as a strategy to identify genes required for synthesis of the Gal alpha (1-4) beta Gal component of Haemophilus influenzae strain RM7004 lipopolysaccharide. Insertion of Tn916 into an open reading frame (ORF) encoding a protein with 75% homology to the Escherichia coli methionine related protein (Mrp) is described. Mutations in mrp resulted in loss of reactivity with monoclonal antibody (mAb) 4C4, which recognises Gal alpha (1-4) beta Gal, and expression of LPS with a different electrophoretic profile to that of wild-type RM7004. An unexpected feature of this mutation was that it appeared to influence the number of copies of 5'-CAAT-3' present in lic2A, a gene which is also required for biosynthesis and phase variable expression of the Gal alpha (1-4) beta Gal LPS epitope.
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PMID:The identification a novel gene required for lipopolysaccharide biosynthesis by Haemophilus influenzae RM7004, using transposon Tn916 mutagenesis. 897 86

Methionine-enkephalin (MENK) is not an effective stimulus for inducing the superoxide (O2-) generation of human neutrophils, but it enhanced the O2- generation stimulated by the chemotactic peptide N-formyl-methionyl-leucyl-phenylalanine (fMLP) or human recombinant interferon gamma (hrIFN gamma) when the cells had been preincubated with MENK for 30 min at 37 degrees C. The priming effect of MENK was not observed with stimulus such as lipopolysaccharide (LPS) or phorbol-12-myristate-13-acetate (PMA). The enhancing effect of MENK was abrogated if cells were treated with protein kinase C (PKC) inhibitor H7 (1-(5-isoquinolinylsulfonyl)-2-methylpiperazine) before fMLP or IFN gamma. This finding indicates that MENK is a potent modulator of human neutrophils and can contribute to inflammatory process.
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PMID:Methionine-enkephalin primes human neutrophils for enhanced superoxide anion production. 904 64

1. Glutathione concentrations in liver and lung fall when food intake or sulphur amino acid intake is inadequate. However, concentrations may be restored during inflammation, despite anorexia, provided that prior sulphur amino acid intake is adequate. 2. We studied the mechanisms of these changes by measuring the effect of sulphur amino acid and protein intake on hepatic glutathione synthesis and gamma-glutamylcysteine synthetase activity, hepatic and lung glutathione concentrations, glutathione reductase and glutathione peroxidase activities in young rats given an inflammatory challenge by intraperitoneal injection of tumour necrosis factor-alpha or endotoxin (lipopolysaccharide). 3. Diets containing 200 g of casein and 8 g of L-cysteine/kg (normal-protein diet), or 80 g of casein and 8 g of L-cysteine, or isonitrogenous amounts of L-methionine or L-alanine (low-protein diets) were fed ad libitum to young Wistar rats for 8 days. Dietary groups were subdivided into three: one subgroup continued feeding ad libitum, a second was given tumour necrosis factor or lipopolysaccharide and killed 24 h thereafter, while the third was pair-fed to the intakes of the second subgroup for 24 h before being killed. 4. Glutathione concentrations in liver and lung were reduced in rats fed the low-protein diet containing alanine, and in all dietary groups when food intake was restricted. The inflammatory challenges restored hepatic glutathione concentrations in all groups but the diet supplemented with alanine, which had an inadequate sulphur amino acid content. In lung, restoration occurred only in animals fed the normal-protein diet. 5. The activity of gamma-glutamylcysteine synthetase, which is rate limiting for glutathione synthesis, was unaffected by dietary or sulphur amino acid intake or by the inflammatory response. Substrate supply may therefore be a major determinant in glutathione synthesis in vivo. 6. Total hepatic glutathione synthesis was affected by food intake, the type and amount of sulphur amino acids in the diet and by inflammation. Total synthesis was 207, 137, 421 and 90 mumol/day for animals fed ad libitum the normal-protein diet, or low-protein diets supplemented with cysteine, methionine or alanine respectively, ad libitum. Pair-feeding resulted in values of 76, 31, 71, and 0 mumol/day respectively. After lipopolysaccharide injection, rates increased to 200, 117, 151 and 56 mumol/day respectively. 8. Reductase and peroxidase activities increased in liver and lung, when low-protein diets which contained supplemental methionine or alanine were consumed ad libitum. A reduction in food intake resulted in enzyme activity changes, which suggested that recycling of glutathione increased in lung and decreased in liver. Injection of tumour necrosis factor reversed this effect. 9. The restoration of glutathione concentrations in liver after an inflammatory challenge is closely associated with an enhanced rate of synthesis and increased recycling. The former is impaired when inadequate sulphur amino acid is consumed before the challenge. In lung, increased recycling of glutathione may help maintain concentrations when food intake is restricted, but not during inflammation.
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PMID:Dietary sulphur amino acid adequacy influences glutathione synthesis and glutathione-dependent enzymes during the inflammatory response to endotoxin and tumour necrosis factor-alpha in rats. 909 11

Endotoxin-induced hepatic acute-phase protein synthesis has been thought to be primarily regulated through cytokines such as interleukin-1 (IL-1) and interleukin-6 (IL-6). Previously, it was found that a 23-kDa murine acute-phase protein, the lipopolysaccharide (LPS)-induced protein (LIP), was synthesized following treatment of hepatocytes in vitro with LPS. Since this protein was also induced by IL-1 and IL-6, the present studies were undertaken to determine if the effect of endotoxin was mediated through these cytokines. Primary cultures of murine hepatocytes were treated with LPS, IL-1, IL-6, or an LPS-stimulated macrophage supernatant in the presence or absence of the IL-1 receptor antagonist (IL-1 RA) and/or an anti-IL-6 antibody. The cells were then radiolabeled with [35S]methionine. LIP was detected by electrophoresis and autoradiography of the secreted proteins. In vitro, IL-1 RA completely inhibited the stimulation of LIP synthesis elicited by IL-1 and the macrophage supernatant, but did not affect LPS-stimulated synthesis of this protein. The anti-IL-6 antibody inhibited IL-6-triggered synthesis of LIP, but had no effect on LPS-stimulated synthesis. Hepatocytes isolated from mice treated in vivo with both IL-1 RA and LPS synthesized LIP to the same degree as hepatocytes isolated from mice treated with LPS alone. LPS-stimulated synthesis of LIP in vitro does not require IL-1 or IL-6 as an obligatory intermediate. These results are consistent with the hypothesis that endotoxin can directly stimulate hepatocyte acute-phase protein synthesis in the absence of cytokines.
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PMID:Effects of cytokine antagonists on the hepatic acute-phase response. 918 75


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