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

We have tested the ability of the 5' flanking region of the lactogen-regulated annexin Icp35 gene to drive the expression of the bacterial chloramphenicol acetyltransferase (CAT) gene in T-47D, HBL-100 and HC11 cells. A construct containing 1,400 bp of the 5' flanking region including the putative promoter, and the first two exons and intervening sequence showed lower activity compared with a similar construct containing only 250 bp of the 5' flanking region. This indicated the presence of negative regulatory elements in the distal 5' flanking region. Experiments were done to determine the effect of lactogens (either ovine prolactin, or human growth hormone) on the cp35 promoter using various hormone treatments, growth conditions and serum supplements. We did not observe any effect of hormones on the expression of the cp35/CAT constructs under the conditions tested.
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PMID:Regulation of the annexin Icp35 gene in transfected mammary gland cell lines. 836 11

Mutations in the 5' nontranslated RNA (5'NTR) of an attenuated, cell culture-adapted hepatitis A virus (HAV), HM175/P16, enhance growth in cultured African green monkey kidney (BS-C-1) cells but not in fetal rhesus monkey kidney (FRhK-4) cells (S. P. Day, P. Murphy, E. A. Brown, and S. M. Lemon, J. Virol. 66: 6533-6540, 1992). To determine whether these mutations enhance cap-independent translation directed by the HAV internal ribosomal entry site (IRES), we compared the translational activities of the 5'NTRs of wild-type and HM175/P16 viruses in two stably transformed cell lines (BT7-H and FRhK-T7) which constitutively express cytoplasmic bacteriophage T7 RNA polymerase and which are derived from BS-C-1 and FRhK-4 cells, respectively. Translational activity was assessed by monitoring expression of a reporter protein, chloramphenicol acetyltransferase (CAT), following transfection with plasmid DNAs containing bicistronic T7 transcriptional units of the form luciferase-5'NTR-CAT. In both cell types, transcripts containing the 5'NTR of HM175/P16 expressed CAT at levels that were 50- to 100-fold lower than transcripts containing the IRES elements of Sabin type 1 poliovirus or encephalomyocarditis virus, confirming the low activity of the HAV IRES. However, in BT7-H cells, transcripts containing the 5'NTR of wild-type virus. This translational enhancement was due to additive effects of a UU deletion at nucleotides 203 and 204 and a U-to-G substitution at nucleotide 687 of HM175/P16. These mutations did not enhance translation in FRhK-T7 or Huh-T7 cells (a T7 polymerase-expressing cell line derived from human hepatoblastoma cells) or in vitro in rabbit reticulocyte lysates. These results demonstrate that mutations in the 5'NTR of a cell culture-adapted HAV enhance viral replication by facilitating cap-independent translation in a cell-type-specific fashion and support the concept that picornaviral host range is determined in part by differences in cellular translation initiation factors.
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PMID:Mutations within the 5' nontranslated RNA of cell culture-adapted hepatitis A virus which enhance cap-independent translation in cultured African green monkey kidney cells. 855 62

Twenty-four base pairs of the human antioxidant response element (hARE) are required for high basal transcription of the NAD(P)H:quinone oxidoreductase1 (NQO1) gene and its induction in response to xenobiotics and antioxidants. hARE is a unique cis-element that contains one perfect and one imperfect AP1 element arranged as inverse repeats separated by 3 bp, followed by a "GC" box. We report here that Jun, Fos, Fra, and Nrf nuclear transcription factors bind to the hARE. Overexpression of cDNA derived combinations of the nuclear proteins Jun and Fos or Jun and Fra1 repressed hARE-mediated chloramphenicol acetyltransferase (CAT) gene expression in transfected human hepatoblastoma (Hep-G2) cells. Further experiments suggested that this repression was due to overexpression of c-Fos and Fra1, but not due to Jun proteins. The Jun (c-Jun, Jun-B, and Jun-D) proteins in all the possible combinations were more or less ineffective in repression or upregulation of hARE-mediated gene expression. Interestingly, overexpression of Nrf1 and Nrf2 individually in Hep-G2 and monkey kidney (COS1) cells significantly increased CAT gene expression from reporter plasmid hARE-thymidine kinase-CAT in transfected cells that were inducible by beta-naphthoflavone and teri-butyl hydroquinone. These results indicated that hARE-mediated expression of the NQO1 gene and its induction by xenobiotics and antioxidants are mediated by Nrf1 and Nrf2. The hARE-mediated basal expression, however, is repressed by overexpression of c-Fos and Fra1.
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PMID:Nrf1 and Nrf2 positively and c-Fos and Fra1 negatively regulate the human antioxidant response element-mediated expression of NAD(P)H:quinone oxidoreductase1 gene. 896 64

Lactoferrin, a ferric binding glycoprotein found in milk, can possibly prevent microbial infection of the mammary gland and gastrointestinal tract. To define the regulation of the porcine lactoferrin gene (pLTF), we cloned its 5'-flanking region from a porcine liver genomic library and analyzed the 5' upstream region of approx. 4kb, two exons, and an intron. The transcription start site was localized by primer extension to residue G, which is 41 nucleotides upstream from the ATG start codon. The pLTF 5'-flanking region possesses several putative cis-acting regulatory elements found in both housekeeping and inducible genes; to define their function, they were inserted into a chloramphenicol acetyltransferase reporter construct. The region up to -156 sufficed for basic promoter activity, whereas the region up to -780 was required for maximal promoter activity in porcine testis cells (STcells), kidney cells (PK15 cells) and human mammary epithelial cells (HBL-100 cells). Detailed analysis of this proximal region by DNase I footprinting and electrophoretic mobility shift assays reveals that the ubiquitous factors SP1, AP2 and the mammary gland-specific factor (MGF) might play significant roles in regulating the transcription of the pLTF gene.
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PMID:Characterization and functional analysis of the porcine lactoferrin gene promoter. 966 28

Tumour necrosis factor-alpha (TNF-alpha) plays a key role in orchestrating the complex events involved in inflammation and immunity. Accordingly, TNF-alpha has been implicated in a wide range of autoimmune and infectious diseases, but also in conditions such as obesity and insulin resistance. The regulation of TNF-alpha expression in man is indicated to be partly genetically determined. We therefore screened a 1263 bp section of the proximal promoter of the TNF-alpha gene for common genetic variants affecting the transcriptional activity of the gene. Here we report the characterization of a common functional polymorphism in the promoter region of the TNF-alpha gene, a C-->A substitution at position -863. Electromobility shift assays provided evidence for a distinct difference in the binding of monocytic and hepatic nuclear factors to the -863C and -863A alleles. The rare -863A allele was associated with 31% lower transcriptional activity ( P < 0.001) in chloramphenicol acetyltransferase (CAT) reporter gene studies in human hepatoblastoma (HepG2) cells, indicating that the-863C/A polymorphism influences the basal rate of transcription of the TNF-alpha gene in vitro. Allele frequencies were 0.83/0.17 amongst 254 apparently healthy men of Swedish origin, aged 35-50 years. In 156 men, the -863C/A polymorphism was associated with the serum TNF-alpha concentration, carriers of the rare A allele having a significantly lower TNF-alpha level ( P < 0.05). It is concluded that the common-863C/A polymorphism in the promoter region of the TNF-alpha gene is functional in vitro in monocytic and hepatic cells and influences the serum TNF-alpha concentration in vivo in healthy middle-aged men.
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PMID:A common functional polymorphism (C-->A substitution at position -863) in the promoter region of the tumour necrosis factor-alpha (TNF-alpha) gene associated with reduced circulating levels of TNF-alpha. 1040 Sep 91

Xenobiotics and antioxidants induce expression of detoxifying enzymes including NAD(P)H: quinone oxidoreductase (NQO1), NRH:quinone oxidoreductase (NQO2), and glutathione S-transferase Ya (GST Ya), presumably to provide protection to cells against electrophilic and oxidative stress. Antioxidant response elements (AREs) have been found in the promoter regions of the various detoxifying enzyme genes. An ARE is required for basal expression and induction of the various detoxifying enzyme genes in response to xenobiotics and antioxidants. In this study, we demonstrated that exposure of cells to xenobiotics [e.g. beta-naphthoflavone (beta-NF)] and antioxidants [e.g. tert-butyl hydroquinone (t-BHQ)] also induced the expression of the proto-oncogene c-jun. The induction of c-jun gene expression followed kinetics similar to the induction of NQO1 and NQO2 genes with respect to the level and time of exposure. Sequence analysis of the c-jun gene promoter revealed the presence of an ARE between nucleotides -538 and -514. The c-jun ARE was highly homologous to the AREs from genes encoding NQO1, NQO2, and GST Ya. Constructs containing the c-jun ARE and 1.7 and 4.5 kb of the c-jun promoter ligated to the chloramphenicol acetyltransferase (CAT) gene, upon transfection in human hepatoblastoma (Hep-G2) cells, expressed the CAT gene, which was inducible with beta-NF and t-BHQ. Band shift assays indicated binding of two specific nuclear protein complexes with the c-jun gene ARE. The faster running c-jun gene ARE-nuclear protein complex was specifically competed out by unlabeled NQO1 and GST Ya gene AREs. These results suggest that c-jun gene expression is coordinately induced and regulated with detoxifying enzyme genes in response to xenobiotics and antioxidants. The results also suggest involvement of an ARE-mediated mechanism of induction of c-jun gene expression. However, a comparison of fold induction of endogenous c-jun gene and transfected c-jun promoter/ARE-CAT constructs indicated involvement of another ARE upstream of the 4.5-kb promoter and/or additional mechanisms such as stabilization of c-Jun RNA in response to exposure to xenobiotics and antioxidants.
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PMID:Coordinated induction of the c-jun gene with genes encoding quinone oxidoreductases in response to xenobiotics and antioxidants. 1041 96


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