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)

Adenovirus infection of hepatoma cells inhibited transcription of the phosphoenolpyruvate carboxykinase (GTP) (EC 4.1.1.32) (PEPCK) gene and virtually eliminated transcription of a chimeric gene which contained the PEPCK promoter linked to the structural gene for chloramphenicol acetyltransferase (CAT). This effect is due to the viral protein E1A, since adenovirus containing a deletion in the E1A gene did not repress transcription from the PEPCK promoter. Both the 243R and 283R products of the E1A gene were effective. The conserved region 1 (CR-1) domain of E1A was required for this effect. Treatment of hepatoma cells with 8-bromo-cAMP or transfection with plasmids coding for the catalytic subunit of protein kinase A, CAAT/enhancer binding protein alpha (C/EBP), or Jun, all potent inducers of PEPCK gene transcription, did not relieve the inhibition caused by E1A. This inhibition does not appear to be mediated by major enhancer elements and in the PEPCK gene since transcription from the PEPCK promoter containing block mutations in binding domains for C/EBP and cAMP regulatory element binding protein (CREB) was also inhibited by E1A. Transcription of chimeric genes containing two copies each of the major cAMP response domains (CRE-1 and P-3) linked to a neutral promoter and fused to the CAT structural gene was stimulated by the catalytic subunit of protein kinase A, but this effect was totally inhibited by E1A. The strong repressive effect of E1A on PEPCK gene transcription seems to involve an interruption of an obligatory interaction between factors which bind to the cAMP response element in the PEPCK promoter and the TATA box.
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PMID:Adenovirus E1A represses the cyclic AMP-induced transcription of the gene for phosphoenolpyruvate carboxykinase (GTP) in hepatoma cells. 131 Mar 18

In this study we have used a panel of vectors expressing the chloramphenicol acetyltransferase (CAT) reporter gene under the control of different regulatory elements to optimize gene transfer and expression in primary B lymphocytes. The Moloney murine leukemia virus long terminal repeat (MoMLV LTR) and the SV40 early region promoters, while functional in transfected plasmacytoma cell lines, did not give rise to detectable CAT activity following transfection into primary activated mouse or human B lymphocytes. In contrast, the human cytomegalovirus immediate-early (HCMV-IE) enhancer/promoter functioned in both established and primary B cells. The highest expression levels in the primary cells were obtained with vectors containing the Adenovirus 2 major late promoter or the HCMV-IE enhancer/promoter in combination with the Adenovirus 2 tripartite leader and VA genes. These latter expression cassettes were placed in a retroviral vector with the aim of combining their capacity for high-level gene expression with the efficient stable gene transfer afforded by retroviral infection. Several retroviral constructs were made, some of which were able to generate high virus titers. However all of these underwent deletions during the process of retroviral infection, as judged by Southern analysis of infected cells, indicating that they were not optimal gene transfer vectors. The HCMV enhancer/promoter, which was the most active of the other expression cassettes tested in the primary B cells, was inserted into a retroviral vector which also expressed the hph gene under the transcriptional control of the retroviral LTR. This vector did not undergo rearrangement during the process of retroviral infection, as judged by Southern analysis. The CAT gene was inserted downstream of the HCMV promoter in this vector, and a high-titer retroviral stock was generated. Primary B lymphocytes infected with this vector gave high levels of CAT activity, under conditions in which parallel experiments with the hph drug resistance marker showed that one in 20 of the cells were infected. These experiments demonstrate efficient gene transfer and expression in primary B lymphocytes in vitro.
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PMID:Efficient gene transfer and expression in primary B lymphocytes. 186 23

Activities of heterologous promoters and enhancers in cultured rainbow trout liver cells were examined employing the bacterial chloramphenicol acetyltransferase gene as the reporter. SV40 promoter-enhancer and Rous sarcoma virus long terminal repeat directed constitutive expression at high levels. Moloney murine leukemia virus long terminal repeat and SV40 promoter combined with Adenovirus type 2 enhancer were also constitutively expressed. Drosophila Hsp70 promoter was activated when the transformed cells were cultured at 25 degrees C, a higher temperature than the temperature normally used, in faithful response to heat shock.
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PMID:Constitutive and inducible expression of a transgene directed by heterologous promoters in a trout liver cell line. 226 33

The genome of bovine leukemia virus (BLV) encodes a transcriptional trans-activator p38tax (also referred to as pXBL-I) which amplifies the virus gene expression driven by its long terminal repeat (LTR). It was proposed that activation of cellular gene expression by p38tax might be involved in the mechanism of B-cell transformation caused in vivo by BLV infection. Here, we report that the U3 region of BLV LTR contains multiple regulatory elements responsive to p38tax. A core element composing the p38tax-inducible U3 structure is suggested to be a heptanucleotide motif of 5'TGACGTCA3', the consensus sequence proposed for a cAMP-responsive element (CRE) and for the binding sites of a cellular transcription factor (ATF). Adenovirus-5 E3 and E4, c-fos and somatostatin regulatory regions containing CRE/ATF-element exhibited responsiveness to p38tax in a chloramphenicol acetyltransferase transient expression assay. These suggest that in BLV-infected cells, cellular gene expression might be induced abnormally by the virus trans-activator through ATF or ATF-like factors.
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PMID:Bovine leukemia virus trans-activator p38tax activates heterologous promoters with a common sequence known as a cAMP-responsive element or the binding site of a cellular transcription factor ATF. 254 18

We examined E1A gene expression by two evolutionarily divergent human adenoviruses, type 5 (subgroup C) and type 3 (subgroup B). Adenovirus type 3 (Ad3)-infected A549 cells contained much larger amounts of E1A-specific RNA than adenovirus type 5 (Ad5)-infected cells, from very early (3 h) through the late stages (20 h) after infection. The appearance of such abundant Ad3 E1A transcripts was delayed after infection of Ad5 E1A-expressing 293 cells, suggesting a down regulation of the Ad3 E1A gene by Ad5 E1A gene products. In a reciprocal manner, coinfection of A549 cells led to typically early and intense Ad3 E1A transcription and strongly inhibited transcription of the Ad5 E1A gene. Transient expression assays were developed so that the autoregulation of the E1A gene could be studied apart from the more complex background of infected cells. The DNA sequence surrounding the transcription start site of the Ad3 E1A gene was placed 5' to the sequence which encodes the bacterial chloramphenicol acetyltransferase gene. Cotransfection of HeLa cells with Ad3 or Ad5 E1A-expression plasmids increased the expression of the Ad3 E1A promoter-driven chloramphenicol acetyltransferase gene. Taken together, these results suggest dual autoregulatory features of adenovirus E1A gene expression. The positive and negative effects appear to be temporally distinguished under different conditions, both in viral infection and in transient assays with plasmid-cloned genes.
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PMID:Autoregulation of adenovirus E1A gene expression. 293 96

The pancreatitis-associated protein I (PAP I) is a pancreatic secretory protein expressed in pancreas during acute pancreatitis but not in the healthy pancreas. The promoter of the PAP I gene thus represents a potential candidate to drive expression of therapeutic molecules to the diseased pancreas. In this work, we have constructed recombinant adenoviruses harboring the chloramphenicol acetyltransferase (CAT) gene driven by several fragments of the PAP I promoter and have characterized their properties in vitro and in vivo. In vitro studies showed that the transduction of the pancreatic cell line AR-42J with these adenoviruses led to low levels of CAT activity in basal conditions. After stimulation with a combination of interleukin-6 and dexamethasone or after induction of oxidative stress, CAT activity was strongly induced, a characteristic of the endogenous PAP I gene. Stimulation was maximal when constructs comprised 1253 base pairs of the PAP I promoter, upstream from initiation of transcription, and decreased with shorter fragments of 317, 180, 118 or 61 base pairs. The recombinant adenovirus containing the CAT gene under the control of the PAP I promoter fragment (-1253/+10) was also tested in vivo. Following administration by intravenous injection into mice, CAT activity was measured in several tissues 96 h later. In healthy animals, low but significant CAT activity was detected in pancreas, compared with near background values observed in the other tissues. When experimental acute pancreatitis was induced, CAT expression was strongly enhanced only in pancreas. In control experiments with adenoviruses in which the CAT gene was driven by the cytomegalovirus promoter, higher levels of expression were observed in all tissues. Expression was not modified after induction of acute pancreatitis. In conclusion, this study shows that (i) a recombinant adenovirus containing a fragment of the PAP I promoter allows specific targeting of a reporter gene to the mouse pancreas and (ii) expression of the reporter gene in pancreas is induced during acute pancreatitis. Adenovirus-mediated gene therapy of acute pancreatitis is therefore conceivable.
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PMID:The pancreatitis-associated protein I promoter allows targeting to the pancreas of a foreign gene, whose expression is up-regulated during pancreatic inflammation. 903 94