Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.7.48 (transcriptase)
 9,479 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Human intercellular adhesion molecule-1 (ICAM-1), a specific ligand for the lymphocyte function-associated Ag-1 (LFA-1), plays an important role in leukocyte-endothelial cell interactions. It is induced by proinflammatory cytokines such as IL-1, TNF-alpha, or IFN-gamma. However, little is known concerning the intracellular regulatory mechanisms which trigger ICAM-1 up-regulation. In order to study potential regulatory elements involved in ICAM-1 induction we have cloned the human ICAM-1 gene and 5 kb of its 5'-regulatory region. The sequence of the cDNA was found to be distributed over seven exons separated by six introns, whereby each of the five extracellular Ig-like domains of ICAM-1 is encoded by its own exon. The upstream sequence harbors a number of sequence motifs implicated in the regulation and expression of eukaryotic genes, including binding sites for the transcription factors SP-1, AP-1, and NF-kB. Primer extension and S1 nuclease analysis revealed two transcription initiation sites 319 bp and 41 bp upstream of the translation start site. Consensus TATA boxes were found at the expected positions about 25 bp upstream of both start sites. Reverse transcriptase polymerase chain reaction showed differential use of the two TATA boxes in A549 and HS913T cells. Both RNA seem to code for the same for of ICAM-1 protein. For regulation studies a 1.3-kb EcoRI/SalI fragment of the 5'-flanking region was used to promote transcription of a linked luciferase reporter gene in transient-transfection assays in A549 and HS913T cells. Treatment of A549 cells with IL-1 or TNF-alpha resulted in a two- or fourfold increase in luciferase activity. Furthermore, a sixfold induction could be achieved after treatment with the phorbol ester PMA. In contrast, agents that increase intracellular cAMP levels did not induce luciferase activity. Northern blot analysis was used to investigate the kinetics of ICAM-1 mRNA synthesis upon induction with TNF-alpha and PMA. These data suggest that the up-regulation of ICAM-1 by cytokines occurs at least partly at the transcriptional level. Deletion analysis of the 1.3-kb fragment of the 5'-flanking region revealed sequences responsible for promotion and inhibition of transcription. In particular, two functionally distinct regions have been characterized: a short fragment containing an NF-kB binding site has been shown to function as an activator, followed immediately downstream by a sequence acting as a silencer element. Therefore, ICAM-1 gene expression seems to be modulated by multiple cis-acting elements.
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PMID:Cloning of the human gene for intercellular adhesion molecule 1 and analysis of its 5'-regulatory region. Induction by cytokines and phorbol ester. 168 Sep 19

Human umbilical vein endothelial cells were subjected to controlled levels of shear stress in a flow-loading apparatus, and changes in the expression of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule 1 (VCAM-1) were measured by flow cytometry. Application of shear stress (15 dynes/cm2) increased the cell surface expression of ICAM-1 2.7 times the control level 4 hr after the onset of flow, while it caused no change in VCAM-1 expression. The increase of ICAM-1 expression by shear stress was time- and force-dependent and reversible. Flow loading using perfusates with different viscosity revealed that the increase in ICAM-1 was shear-stress- rather than shear-rate-dependent. Reverse transcriptase/polymerase chain reaction analysis showed upregulation of ICAM-1 mRNA levels by shear stress, whose time course closely paralleled that of the cell surface protein. These results suggest that shear stress generated by blood flow acts as a regulator of cell adhesion molecule expression on vascular endothelial cells.
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PMID:Flow stimulates ICAM-1 expression time and shear stress dependently in cultured human endothelial cells. 783 15

The adhesion molecule intercellular adhesion molecule-1 (ICAM-1), in addition to its membrane-associated form (mICAM-1), also exists as a soluble form (sICAM-1). sICAM-1 is capable of binding to lymphocyte function associated antigen-1 (LFA-1) molecules, and production of sICAM-1 is therefore thought to have immunomodulatory consequences. The present study, which employed normal human keratinocytes as a model for sICAM-1-producing cells, was conducted to determine the mechanism responsible for the production of sICAM-1 and to develop a strategy for specific inhibition of sICAM-1 production. Stimulation of keratinocytes with recombinant human gamma-interferon (rhIFN-gamma) induced both expression of mICAM-1 and production of sICAM-1. Western blot analysis revealed that keratinocyte-derived sICAM-1, compared to mICAM-1, had a smaller molecular size, approximately a 7-kD difference. Neither by Northern blot analysis nor by reverse-transcriptase polymerase chain reaction (RT-PCR) was any evidence for alternatively spliced ICAM-1 mRNA obtained. Addition of the protease inhibitors iodoacetamide and E-64, however, inhibited the production of sICAM-1 in a dose-dependent manner. The involvement of proteolytic cleavage in the production of sICAM-1 was corroborated in minimal peptide protection assays, in which minimal peptides covering the potential cleavage site of ICAM-1 were added to sICAM-1-producing keratinocytes. One of these peptides, ICAM cleavage inhibitory peptide (ICAM-CIP), inhibited the production of sICAM-1 without affecting mICAM-1 expression. These studies demonstrate that sICAM-1 production in human keratinocytes is due to proteolytic cleavage, and that the oligopeptide ICAM-CIP may specifically inhibit this mechanism. The capacity of ICAM-CIP to selectively prevent production of sICAM-1 may be useful for the development of novel therapeutic approaches relevant for the management of inflammation and cancer.
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PMID:Analysis of the production of soluble ICAM-1 molecules by human cells. 864 65

Hyperoxia-exposure results in neutrophil accumulation and edema in the exposed lung. Intercellular adhesion molecule-1 (ICAM-1), a ligand for neutrophil beta 2 integrins, is upregulated in hyperoxia-exposed lungs and enhances neutrophil-mediated injury. Because tumor necrosis factor-alpha (TNF-alpha) and interleukin-1 (IL-1) are potent inducers of ICAM-1, we investigated whether TNF-alpha and IL-1 beta mRNA increase prior to the increase in ICAM-1 mRNA in hyperoxia-exposed mouse lungs. We exposed mice to > 95% oxygen for up to 96 h, isolated lung RNA, and assessed ICAM-1, TNF-alpha, and IL-1 beta mRNA by Northern blotting. We found that neither, TNF-alpha nor IL-1 beta mRNA was detectable prior to 96 h, while ICAM-1 mRNA increased by 48 h. To further assess TNF-alpha and IL-1 beta mRNA, we employed quantitative reverse-transcriptase polymerase chain reaction (RTPCR) using a mimic DNA (mimic) species as an internal control for PCR. Mimic DNA was identical to reverse-transcribed cDNA (wild type), except for 147 bp of irrelevant DNA ligated into the original cDNA. For each lung RNA sample we reverse transcribed total lung RNA and coamplified the resulting wild-type cDNA with serial dilutions of mimic DNA in a PCR containing [32P] dCTP. After PCR, we electrophoresed the samples and determined the concentration of TNF-alpha and IL-1 beta wild-type cDNAs by the ratios of wild type to mimic counts. We found no increase in TNF-alpha or IL-1 beta mRNA through 72 h of hyperoxia exposure, while there was an approximately 10-fold increase in TNF-alpha mRNA and a 35-fold increase in IL-1 beta mRNA within 2 h in the lungs of animals exposed to endotoxin. In conclusion, our data suggest that TNF-alpha and IL-1 beta are not responsible for the upregulation of ICAM-1 in hyperoxia-exposed mouse lungs.
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PMID:Hyperoxic increases in lung ICAM-1 mRNA are independent of TNF-alpha and IL-1 beta mRNA. 937 69

Reflux nephropathy (RN) is a major cause of end-stage renal failure in children and young adults. Intercellular adhesion molecule-1 (ICAM-1), a cell surface glycoprotein, has a role in the regulation of interaction among immune cells. It has been demonstrated that increased levels of tubular ICAM-1 correlate with an extent of tubular damage in diabetic nephropathy. We hypothesized that ICAM-1 local synthesis is altered in reflux nephropathy and therefore designated this study to investigate ICAM-1 expression in RN. The kidney specimens from six patients with severe reflux nephropathy secondary to primary vesicoureteral reflux were obtained at the time of nephrectomy. Control materials included normal kidney specimens obtained from three adult patients during partial nephrectomy for an incidentaloma. Fluorescent immunohistochemistry was carried out using monoclonal antibodies to ICAM-1 utilizing confocal laser scanning microscopy. Reverse transcriptase polymerase chain reaction (RT-PCR) was performed to evaluate the relative amount of ICAM-1. In the control kidneys, there was lack of ICAM-1 immunoreactivity in the interstitium and proximal tubules and moderate immunoreactivity in the glomerulus. In the refluxing kidney there was strong ICAM-1 immunoreactivity in the glomerulus, interstitium and proximal tubules. The RT-PCR showed strong ICAM-1 mRNA expression in the refluxing kidneys and absent or weak ICAM-1 expression in the controls. Our findings of increased expression of ICAM-1 in the severe reflux nephropathy kidney suggests that ICAM-1 may play a role in the pathogenesis of renal parenchymal damage associated with RN.
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PMID:ICAM-1 expression is upregulated in reflux nephropathy. 1275 65

To determine the role of NF-kappa B in ischemia reperfusion (I/R) injury of the rat liver, rats underwent partial hepatic ischemia and reperfusion. The left and median lobes of the liver were subjected to ischemia for 90 min followed by reperfusion for defined times. NF-kappa B activity was analyzed by electrophoretic mobility shift assay (EMSA). Semiquantitative reverse-transcriptase polymerase chain reaction was used to analyze TNF-alpha and ICAM-1 mRNA levels. Results showed during liver I/R injury, NF-kappa B activation was induced in a time dependent manner. NF-kappa B was activated within 1 h and 2 h after the initiation of reperfusion and decreased after 4 h. Messenger RNA expression of TNF-alpha and ICAM-1 were increased after the reperfusion of 2 h. It was concluded that during hepatic I/R injury, NF-kappa B was activated and could bind to special sequence in the promoters of budget genes, which can up-regulate the expression of TNF-alpha and ICAM-1 mRNA to result in ischemia reperfusion injury of the rat liver.
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PMID:Role of NF-kappa B in liver ischemia reperfusion injury of rats. 1297 36

Rosette nanotubes (RNT) are a new class of metal-free organic nanotubes synthesized through self-assembly. Because of the wide range of potential biomedical applications associated with these materials, it is necessary to evaluate their potential in vitro toxicity. Here the cytotoxicity of a lysine-functionalized nanotube (RNT-K) in a human Calu-3 pulmonary epithelial cell line is investigated. The cells were treated with media only (control), lysine (50 mg mL(-1)), RNT-K (1, 5, and 50 microg mL(-1)), Min-U-Sil quartz microparticles (QM; 80 microg mL(-1)), and lipopolysaccharide (LPS; 1 microg mL(-1)). The supernatants were analyzed at 1, 6, and 24 h after treatment for the expression of three proinflammatory mediators: IL-8, TNF-alpha and EMAP-II. Cellular viability determined with the Trypan blue assay is significantly reduced in the QM and high-dose RNT-treated groups. TNF-alpha and EMAP-II are undetectable by enzyme-linked-immunosorbent assay (ELISA) in the supernatant of all groups. Although IL-8 concentrations do not differ between treatments, its concentrations increase with time within each of the groups. Quantitative reverse-transcriptase polymerase chain reaction (qRTPCR) of IL-8 mRNA shows increased expression in the high-dose RNT-treated groups at both 1 and 6 h, while an adhesion molecule, ICAM-1 mRNA, shows the greatest increase at 6 h in the QM-treated group. In summary, RNT-K neither reduces cell viability at moderate doses nor does it induce a time-dependent inflammatory response in pulmonary epithelial cells in vitro.
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PMID:Low inflammatory activation by self-assembling Rosette nanotubes in human Calu-3 pulmonary epithelial cells. 1853 89