Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.3.1.28 (chloramphenicol acetyltransferase)
 5,100 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To understand the mechanisms involved in dsRNA-induced gene expression, we analyzed the poly(I/C)-induced transcription of the IFN-inducible chemokine gene IP-10 using the GRE cell line in which type I IFN genes have been deleted. Accumulation of IP-10 mRNA in GRE cells was more strongly stimulated by treatment with dsRNA than by IFN-alpha or IFN-gamma and was independent of protein synthesis. This same pattern of response was produced when GRE cells were transiently transfected with a plasmid containing 243 bases of sequence from the promoter of the murine IP-10 gene linked to the chloramphenicol acetyltransferase reporter gene. Deletion- and site-specific mutagenesis of the 243 base pair fragment indicated that an ISRE located between residues -204 and -228 was a primary target site for the action of dsRNA on this promoter. This was confirmed by results showing that two copies of this ISRE tandemly arrayed in front of the thymidine kinase promoter were able to mediate reporter gene transcription in dsRNA-stimulated cells. At least one of the two NF kappa B binding sites present in the 243 base pair IP-10 promoter is also necessary for response to dsRNA; mutation of both sites eliminates promoter activity. Thus the ISRE and one NF kappa B site cooperate to produce transcriptional response to dsRNA.
 ...
PMID:Interferon-stimulated response element and NF kappa B sites cooperate to regulate double-stranded RNA-induced transcription of the IP-10 gene. 789 55

The hepatitis delta virus (HDV) genome consists of circular ssRNA which has extensive intramolecular complementarity and can form a dsRNA rod-like structure. If such RNA species were to exist in an unmasked form in cells, they would be expected to induce interferon (IFN) expression and activate two IFN-inducible dsRNA-dependent enzymes with anti-viral activity, namely the dsRNA-dependent protein kinase (PKR) and 2',5' oligoadenylate (2',5' A) synthetase. Since the virus replicates to high copy number for prolonged periods in infected cells it is apparently able to evade these antiviral mechanisms. The RNA genome may be masked and fail to induce or activate the antiviral response, or the virus may inhibit such a response. Treatment of a hepatoma cell line, Huh7, and a fibrosarcoma cell line, HT1080, stably transfected with a trimeric HDV cDNA construct, with IFN-alpha or IFN-gamma for up to seven days failed to influence the level of expression of genomic or antigenomic HDV RNA, or delta antigen (Ag). This is consistent with either failure of activation or inhibition of the IFN response. However the induction of several IFN-responsive genes, including PKR, 2',5' A synthetase and class I MHC is normal and cotransfection of a construct expressing delta Ag did not affect expression from an IFN-inducible chloramphenicol acetyltransferase construct. In addition, the activation of PKR is not inhibited in HDV-expressing cells and antiviral assays suggest that the ability of these cells to mount an antiviral response to at least two cytopathic viruses is unaffected. IFN-beta is inducible normally by dsRNA in cells transfected with the delta cDNA trimer. We conclude that HDV replication is not inhibited by IFN-alpha or IFN-gamma, even though the responses of cells expressing HDV RNA and antigen to IFN and dsRNA are intact.
 ...
PMID:Hepatitis delta virus replication in vitro is not affected by interferon-alpha or -gamma despite intact cellular responses to interferon and dsRNA. 791 7

The 5' terminal flanking region of the interferon-inducible gene, 202, contains an interferon-stimulable response element (ISRE), called a GA box, that confers inducibility by interferon(IFN)-alpha, but not by IFN-gamma, on a reporter gene, such as the chloramphenicol acetyltransferase (CAT). Nuclear extracts from L1210 murine leukemia cells, stimulated for various periods of time with IFN-alpha, were mixed with 32P-labeled GA box and analyzed for the presence of retarded complexes in electrophoretic-mobility-shift assays. In addition to a few constitutive retarded complexes, an inducible GA box-binding activity (GAbf-1) appeared after 5 min, peaked at about 2 h, and was still abundant 12 h after IFN-alpha treatment. In the cytoplasmic fraction GAbf-1 was not detectable before 30 min, continued to increase up to 2 h, but had disappeared within 12 h. GAbf-1 activity was not observed in nuclear extracts treated with IFN-gamma, and was not inhibited by prior treatment with the protein-synthesis inhibitor cycloheximide. When the binding properties of GAbf-1 were compared with those of ISGF-3, the primary transcriptional activator for IFN-alpha-induced genes, a different pattern of retarded complexes was observed. Moreover, as observed by immunoblotting analysis, nuclear extracts from IFN-alpha-treated L1210 cells did not contain the p91/84 subunit of the ISGF3, the best characterized nuclear complex activated by IFN-alpha. Altogether these results indicate that GAbf-1 may be a novel transcription factor exploited by IFN-alpha to activate the 202 inducible gene in murine pre-B leukemia cells.
 ...
PMID:Characterization of nuclear factors involved in 202 gene induction by interferon-alpha in murine leukemia cells. 817 52

Treatment of NIH 3T3 fibroblasts with interferon-alpha or interferon-gamma (IFN-alpha or IFN-gamma) significantly reduced murine cytomegalovirus (MCMV) replication. Determination of viral DNA in the nuclei of the infected cells before onset of DNA replication demonstrated that virus uptake, transport to the nucleus, and DNA stability were not decreased. Analysis of the virus specified mRNAs soon after infection revealed that in the cells exposed to IFNs expression of the immediate early (IE) genes was strongly reduced. Nuclear run-off transcription analysis showed that this inhibition is due to significant reduction of IE gene transcription rates following IFN treatment. Since transcription of the MCMV IE region is regulated by a strong enhancer element, a construct containing the chloramphenicol acetyltransferase (CAT) reporter gene, driven by an 1.2 kb segment spanning the enhancer and IE1/3 promoter region of the IE transcription unit, was transfected into NIH 3T3 cells. Treatment with IFN-alpha or IFN-gamma after transfection strongly reduced CAT activity compared to untreated controls. In an attempt to define a negative IFN-responsive element in the IE enhancer, a series of deletion mutants driving the CAT reporter gene were transfected into NIH 3T3 cells that were then treated with IFN-alpha. With the sole exception of the construct containing the minimal MCMV IE1/3 promoter (-102 to the cap site), all other deletion mutants were strongly down-regulated by IFN-alpha-treatment. Taken as a whole, these results suggest that IFNs inhibit MCMV replication by impairing the transcription of the IE transcription units, and that this negative regulation is carried out by sequences scattered throughout the IE enhancer region.
 ...
PMID:Interferons inhibit onset of murine cytomegalovirus immediate-early gene transcription. 821 66

Interferon (IFN)-gamma induces the expression of the indoleamine 2, 3-dioxygenase (INDO) gene in human cells, which plays a role in the inhibitory effect of IFN-gamma on intracellular pathogens and on cell proliferation. Earlier studies established that the IFN-gamma-inducible expression of the INDO gene was dependent on two upstream elements: (i) a 14-base pair sequence homologous to an interferon-stimulated response element (ISRE) sequence found in IFN-alpha-inducible genes and (ii) a 9-base pair palindromic sequence (palindromic element (PE) II) homologous to an interferon-gamma-activated site (GAS) element found in IFN-gamma-inducible genes. A second GAS element (PE I), between ISRE and PE II, was ineffective in supporting a response to IFN-gamma. Studies were carried out to determine the distinction between the two GAS elements and the relative role of the two elements (ISRE and PE II) required for a response to IFN-gamma. The PE I element was able to form a complex with IFN-gamma-activated p91 (STAT1) factor but with lower efficiency than the complex formed with PE II sequence. However, switching the positions of PE I and II sequences in reporter plasmid constructs (containing chloramphenicol acetyltransferase gene) showed that both PE I and PE II were able to support a response to IFN-gamma if located at the position of PE II but not at the position of PE I. Increasing the distance between the ISRE and PE II also affected the level of response, suggesting that the relative position of the two elements is important for optimal stimulus. To explore whether an interaction between the IFN-gamma-regulated factors (IRF-1 and p91) binding to the ISRE and PE II might be important, we tested whether the ISRE sequence could be replaced by another response element, NF-kappaB. The plasmid construct with NF-kappaB element in place of the ISRE was responsive to IFN-gamma, indicating that an interaction between the IRF-1 and p91 factors was not required. The results indicate that the response of INDO gene to IFN-gamma depends on a cooperative role of IFN-gamma-responsive factors binding to the ISRE and GAS elements.
 ...
PMID:Cooperative role of interferon regulatory factor 1 and p91 (STAT1) response elements in interferon-gamma-inducible expression of human indoleamine 2,3-dioxygenase gene. 866 41

We recently reported that a hypoxia-responsive element mediates a novel pathway of transcriptional activation of the inducible nitric oxide synthase (iNOS) promoter in murine macrophages treated with IFN-gamma plus hypoxia (1% O2). In this study, we investigated the expression of NOS activity and the regulation of NOS induction in IFN-gamma treated ANA-1 murine macrophages or thioglycollate-elicited peritoneal macrophages cultured under hypoxic conditions. We found that murine macrophages stimulated with IFN-gamma plus hypoxia, despite a significant accumulation of iNOS mRNA, did not release nitrite into culture supernatant. However, cytosol from macrophages treated with IFN-gamma plus hypoxia contained significant levels of iNOS protein and enzymatic activity. Experiments in which cells were treated with IFN-gamma plus hypoxia and then cultured in normoxic conditions (20% O2) demonstrated that reoxygenation was required to achieve detectable accumulation of nitrite in the culture supernatant. Furthermore, we demonstrated that IL-4 inhibited IFN-gamma plus hypoxia-dependent induction of iNOS mRNA expression, iNOS protein, and enzymatic activity. Experiments in which ANA-1 macrophages were transfected transiently with the full-length iNOS promoter linked to a chloramphenicol acetyltransferase reporter gene demonstrated that IL-4 also down-regulated the IFN-gamma plus hypoxia-induced activation of the iNOS promoter. These data establish that hypoxia is a costimulus with IFN-gamma for the induction of iNOS activity in ANA-1 macrophages as well as in murine peritoneal macrophages, and they provide the first evidence that IL-4 inhibits hypoxia-inducible gene expression. In addition, our results suggest that hypoxia, which occurs in many pathologic conditions, may play an important role in the activation of murine macrophages.
 ...
PMID:Regulation of inducible nitric oxide synthase expression in IFN-gamma-treated murine macrophages cultured under hypoxic conditions. 880 68

In order to characterize the gene encoding the ligand binding (1(st); alpha) chain of the human IFN-gamma receptor, two overlapping cosmid clones were analyzed. The gene spans over 25 kilobases (kb) of the genomic DNA and has seven exons. The extracellular domain is encoded by exons 1 to 5 and by part of exon 6. The transmembrane region is also encoded by exon 6. Exon 7 encodes the intracellular domain and the 3' untranslated portion. The gene was located on chromosome 6q23.1, as determined by in situ hybridization. The 4 kb region upstream (5') of the gene was sequenced and analyzed for promoter activity. No consensus-matching TATA or CAAT boxes in the 5' region were found. Potential binding sites for Sp1, AP-1, AP-2, and CREB nuclear factors were identified. Compatible with the presence of the Sp1/AP-2 sites and the lack of TATA box, S1-nuclease mapping experiments showed multiple transcription initiation sites. Promoter activity of the 5' flanking region was analyzed with two different reporter genes: the Escherichia coli chloramphenicol acetyltransferase and human growth hormone. The smallest 5' region of the gene that still had full promoter activity was 692 base pairs in length. In addition, we found sequences belonging to the oldest family of Alu repeats, 2 - 3 kb upstream of the gene, which could be useful for genetic studies.
 ...
PMID:The gene for the ligand binding chain of the human interferon gamma receptor. 908 99

RON (recepteur d'origine nantais) is a receptor tyrosine kinase expressed in murine peritoneal resident macrophages and activated by macrophage-stimulating protein (MSP). The objectives of this investigation were to study the RON expression in exudate macrophages and the mechanisms by which RON inhibits inducible nitric oxide synthase (iNOS) expression induced by LPS and IFN-gamma. We found that mouse peritoneal resident and Con A-elicited macrophages collected on day 3 or day 5 express RON. Acute exudate macrophages collected on day 1 did not express RON. Activation of RON inhibited LPS- and IFN-gamma-induced macrophage nitric oxide production and iNOS mRNA accumulation. Similar inhibition was observed also in Raw264.7 macrophage cell lines transfected with human RON cDNA. In these cells, MSP induced RON phosphorylation concomitant with reduced iNOS mRNA expression and protein synthesis. Further, we show that activated RON inhibited the iNOS gene transcription activity as assessed by chloramphenicol acetyltransferase activity in Raw264.7 cells expressing RON. Wortmannin, a specific inhibitor of phosphatidylinositol-3 (PI-3) kinase, prevented the inhibitory effect of RON on the iNOS gene promoter activity and on the nitric oxide production induced by LPS and IFN-gamma. These effects were confirmed further by introducing a dominant-inhibitory PI-3 kinase p85 subunit in RON-expressing Raw264.7 cells. Taken together, our results suggest that RON is expressed in peritoneal macrophages at later stages of inflammation. Activation of RON by MSP in mature exudate macrophages inhibits LPS- and IFN-gamma-induced iNOS synthesis. PI-3 kinase is an important effector molecule required for RON-mediated inhibition of iNOS expression in macrophages.
 ...
PMID:Activation of the RON receptor tyrosine kinase inhibits inducible nitric oxide synthase (iNOS) expression by murine peritoneal exudate macrophages: phosphatidylinositol-3 kinase is required for RON-mediated inhibition of iNOS expression. 979 31

The nuclear body is a cellular structure that appears to be involved in the pathogenesis of acute promyelocytic leukemia and viral infection. In addition, the nuclear body is a target of autoantibodies in patients with the autoimmune disease primary biliary cirrhosis. Although the precise function of the nuclear body in normal cellular biology is unknown, this structure may have a role in the regulation of gene transcription. In a previous investigation, we identified a leukocyte-specific, gamma interferon (IFN-gamma)-inducible autoantigen designated Sp140. The objectives of the present study were to investigate the cellular location of Sp140 with respect to the nuclear-body components PML and Sp100 and to examine the potential role of Sp140 in the regulation of gene transcription. We used adenovirus-mediated gene transfer to express Sp140 in human cells and observed that the protein colocalized with PML and Sp100 in resting cells and associated with structures containing PML during mitosis. In cells infected with the adenovirus expressing Sp140 and incubated with IFN-gamma, the number of PML-Sp100 nuclear bodies per cell increased but immunoreactive Sp140 was not evenly distributed among the nuclear bodies. Sp140 associated with a subset of IFN-gamma-induced PML-Sp100 nuclear bodies. To examine the potential effect of Sp140 on gene transcription, a plasmid encoding Sp140 fused to the DNA-binding domain of GAL4 was cotransfected into COS cells with a chloramphenicol acetyltransferase (CAT) reporter gene containing five GAL4-binding sites and a simian virus 40 enhancer region. The GAL4-Sp140 fusion protein increased the expression of the reporter gene. In contrast, Sp100 fused to the GAL4 DNA-binding domain inhibited CAT activity in transfected mammalian cells. The results of this study demonstrate that Sp140 associates with a subset of PML-Sp100 nuclear bodies in IFN-gamma-treated cells and that Sp140 may activate gene transcription. Taken together, these observations suggest that the nuclear bodies within a cell may be heterogeneous with respect to both composition and function.
 ...
PMID:Structural and functional heterogeneity of nuclear bodies. 1033 Jan 82

In the present report, the effects of IFN-gamma and transforming growth factor beta1 (TGF-beta1) on major histocompatibility complex class II (MHC-II) gene expression in isolated mouse brain microglial cells, in the MH-S macrophage cell line and in the primary mouse macrophage cultures were examined. IFN-gamma is a potent inducer of MHC-II gene and this induction was further elevated in microglia by TGF-beta1, while TGF-beta1 inhibited IFN-gamma, induction in macrophages. The enhancing effect of TGF-beta1 was also detected in microglia at the protein level. Transient transfection of microglia with 5' deletional mutants of the MHC-II IAalpha promoter linked to the chloramphenicol acetyltransferase reporter gene demonstrated that TGF-beta1 acts at the transcriptional level to enhance the MHC-II expression induced by IFN-gamma.
 ...
PMID:Effect of transforming growth factor-beta1 on microglial MHC-class II expression. 1069 7


<< Previous 1 2 3 Next >>