Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

Adrenodoxin reductase (AR; ferridoxin: NADP+ oxidoreductase, EC 1.18.1.2) is a flavoprotein that mediates electron transport from NADPH to all known mitochondrial forms of cytochrome P450. AR mRNA was found in all human adult and fetal tissues examined; however, it was vastly more abundant in tissues that synthesize steroid hormones. The ratio of the 18- form of mRNA lacking 18 alternately spliced bases to the 18+ form was approximately 100:1 and remained constant irrespective of the tissue or hormonal manipulation, indicating that the alternate splicing is a passive nonregulated event. AR protein was unchanged by forskolin treatment of human JEG-3 cytotrophoblast cells for 24 h, but the mRNA diminished. Phorbol 12-myristate 13-acetate and cycloheximide had no effect, even though these agents had the expected effects on P450scc and adrenodoxin mRNAs. cAMP decreased the abundance of AR mRNA expressed from both transfected plasmids and the endogenous gene, indicating the effect was post-transcriptional. AR gene transcription in JEG-3 cells and promoter-chloramphenicol acetyltransferase constructs transfected into JEG-3 cells were unresponsive to forskolin. Powerful basal transcription elements were identified between -46 and -214 bases from the principal transcriptional initiation site, a region containing six elements closely resembling the binding site for transcription factor SP1.
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PMID:cAMP post-transcriptionally diminishes the abundance of adrenodoxin reductase mRNA. 131 50

The ability of the human insulin receptor promoter to direct expression of a linked chloramphenicol acetyltransferase gene was assessed in transient transfections into HepG2 and Hela cells. A 5'-deletional analysis of the promoter showed that regions between -646 and -489 were important for the activity of the proximal promoter. In addition, a possible negative regulatory element was identified between -1311 and -877 and a positive element between -1823 and -1311. DNase I footprint and gel retardation analysis showed that multiple factors bind to the human insulin receptor promoter. In particular, DNase I protection patterns were observed over the Sp1 sites at -620 to -599 and -438 to -392, a TC box at -533, four homopyrimidine/homopurine sites clustered around -1150, and a site at -1420 that contains the motif TGGCCC which has been shown to bind the liver-specific transcription factor LF-A1.
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PMID:Transcriptional regulation of the human insulin receptor promoter. 132 34

DNA sequences required for expression of the mouse cytochrome c oxidase subunit IV (COXIV) promoter were identified by transient expression of recombinant COXIV-chloramphenicol acetyltransferase constructs in COS and NIH-3T3 cells. Activity of the COXIV promoter is shown to depend upon upstream Sp1 binding sequences and two tandemly repeated 21-base pair sequence elements each mapping to sites of mRNA initiation. Each initiation region repeat contains a binding site for an ets-related transcription factor which demonstrates specificity for the characteristic GGAA ets sequence motif and reactivity with an ets domain-directed monoclonal pan ets antibody. The two 21-base pair repeats are sufficient for transcriptional activity suggesting that the ets-related factor may be involved in both transcriptional activation and start site positioning. The ets-related protein found in COS nuclear extracts is shown to be identical or closely related to the GA-binding protein (GABP) by comparison of electrophoretic mobilities and immunological reactivities of DNA-protein complexes formed with purified recombinant expressed GABP alpha and beta subunits. Sp1 and the GABP-related factors also bind to another mouse cytochrome oxidase subunit gene COXVb. The similar promoter features of these two genes suggests a possible means of coordinate transcriptional regulation among such respiratory proteins.
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PMID:The basal promoter elements of murine cytochrome c oxidase subunit IV gene consist of tandemly duplicated ets motifs that bind to GABP-related transcription factors. 133 Oct 86

We have investigated the functional elements involved in cAMP-stimulated transcription of the human ferredoxin gene. Unlike the bovine gene, the human gene lacked a second upstream RNA initiation site as demonstrated by sequence analysis of the exon boundary, lack of upstream RNA, and analysis of the promoter. The presence of a single promoter was determined by testing the ability of various gene segments to drive the expression of the chloramphenicol acetyltransferase gene after transfection into a mouse adrenal cell line Y1. Full promoter activity was conferred by a DNA fragment spanning -209 to +55, although the -94 to +55 fragment already provided some promoter activity. Transcription from the -94 to +55 segment was stimulated by 2-fold when 8-bromo-cAMP was added to the cell. Footprinting analyses showed two GC boxes at -50 to -70 and -87 to -108 were protected by proteins from both Y1 and HeLa cells. Competition experiments showed that a protein with a recognition sequence indistinguishable from Sp1 bound to these sites. When connected to a heterologous TATA box, the sequence at -76 to -42, which contained the proximal GC box, was able to confer a high level of basal transcription and cAMP stimulation. This sequence does not show sequence homology with the known cAMP-responsive element. Mutations or deletion of the Sp 1-binding site showed diminished basal transcription and defined the cAMP responsive sequence to be from -76 to -62. Therefore the cAMP-responsive sequence of the human ferredoxin gene was located at -76 to -62, which was adjacent to the Sp 1-binding site.
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PMID:Transcription of the human ferredoxin gene through a single promoter which contains the 3',5'-cyclic adenosine monophosphate-responsive sequence and Sp 1-binding site. 133 72

Dihydrolipoamide dehydrogenase (E3; EC 1.8.1.4) is the common component of the three mammalian alpha-ketoacid dehydrogenase complexes and the glycine cleavage system. To study regulation of E3 gene expression, a 12-kilobase clone from a human leukocyte genomic library was isolated, and a 1.8-kilobase fragment containing part of the first intron, the first exon, and 1.5 kilobases of the 5' flanking region of the E3 gene was sequenced. The nucleotide sequence of the E3 promoter region revealed consensus sequences for several DNA binding proteins but no apparent TATA box or Sp1 sites. Although the 1.6-kilobase 5' flanking region has a low percentage of G+C (44%), the nucleotide sequence between +1 and -150 base pairs has a G+C content of 67%. Primer extension analysis showed a major transcriptional start site located 95 nucleotides upstream from the translation initiation codon. A series of 5' deletions from the E3 promoter-regulatory region were ligated to the bacterial chloramphenicol acetyltransferase (CAT) gene, and the resulting constructs were transfected into HepG2 cells. The longest E3 promoter-CAT construct had a relatively high level of CAT enzyme activity, and deletion of a promoter element between -769 and -1223 base pairs resulted in a 3-fold increase in reporter gene expression. These results suggest that the human E3 promoter has characteristics of housekeeping and facultative promoters and that a negative regulatory element is present between 769 and 1223 base pairs upstream from the transcription start site.
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PMID:Characterization of the transcriptional regulatory region of the human dihydrolipoamide dehydrogenase gene. 133 63

We have isolated a genomic clone containing the mouse neu gene. The 5' end of the mouse neu gene was localized by Southern analysis, subcloned and characterized. DNA sequence analysis revealed that the promoter region is 67% G+C-rich and lacks a TATA box, although a CAAT box is present. By sequence comparison, we identified several consensus recognition sequences for general transcription factors such as Sp1, E4TF1, AP2, OTF-1 and GCF, as well as recognition sequences for RVF, E1A and GTG, which have recently been identified in the rat neu promoter. Functional promoter activity was demonstrated by the ability of the promoter to drive transcription of the bacterial chloramphenicol acetyltransferase gene. Using a series of 5'-end deletion mutants, we have identified multiple positive and negative cis-acting elements that regulate mouse neu gene transcription.
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PMID:Cloning and characterization of the mouse neu promoter. 134 55

In order to locate the promoter region of the human alpha 2A adrenergic receptor gene we used RNase protection analysis and antisense RNA probes to map the cap site of the alpha 2 transcripts. Prior sequence analysis has shown two potential TATA box motifs in the human alpha 2A adrenergic receptor gene, TATATAT and TATAAAA, located 427 and 1037 base pairs (bp), respectively, upstream of the protein coding region. RNase protection experiments and primer extension show that transcription starts downstream of the distal TATAAAA, indicating that the 5'-untranslated region is approximately 1 kilobase in length. We have used the chloramphenicol acetyltransferase reporter gene and transient transfection into HT29, a human adenocarcinoma cell line that expresses the alpha 2A receptor, to show that as little as 150 bp upstream of the cap site can direct transcription. Sequence analysis shows that although this region contains the TATA box motif it lacks a CCAAT box motif. DNase I footprint analysis of a fragment from -17 to -193 (where +1 is the transcription initiation site), using nuclear extracts from HT29, showed hypersensitive sites (-68/-69) and two protected regions: -70 to -87, which includes a 10-bp palindrome, and -92 to -105, which includes a GC box, a common motif for Sp1 nuclear factor binding. Gel mobility shift assays indicate that Sp1 or a related factor may bind to this GC box. Deletion of the GC box and the palindrome from chloramphenicol acetyltransferase constructs abolishes transcription. We propose that these cis sequences may function in lieu of a CCAAT box to regulate transcription of the human alpha 2A adrenergic receptor gene.
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PMID:Promoter region of the human alpha 2A adrenergic receptor gene. 138 31

The level of fibronectin (FN) gene expression is very high in resting rat 3Y1 cells but greatly decreased in adenovirus E1-transformed cells. To study the mechanism of this down-regulation, nuclear factors binding to the 5'-flanking region of the FN gene were analyzed by gel retardation assay and DNase I footprinting. Nuclear factors that were present in the transformed cells but nearly absent in resting 3Y1 cells interacted with multiple sites of the promoter region. Oligonucleotide competition with the FN promoter-chloramphenicol acetyltransferase (CAT) reporter constructs (pFCAT) for these factors in the transformed cells indicated that all of them had a negative effect on FN gene expression. Of them, a factor(s) (G10BP) binding to the G10 stretch from positions -239 to -230 and to two GC boxes consisting of the G10 stretch with one internal C residue insertion from positions -105 to -95 and -54 to -44 had the strongest repressive activity. Introduction of substitutive mutations into these G-rich sequences resulted in the increase in CAT activity of pFCAT in the transformed cells. The recognition sequences of G10BP and Sp1 overlap in two GC boxes. G10BP has stronger affinity for heparin and GC boxes than does Sp1, suggesting that G10BP may repress FN gene transcription by displacing Sp1.
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PMID:Induction of E1A-responsive negative factors for transcription of the fibronectin gene in adenovirus E1-transformed rat cells. 140 98

The activity of the human O6-methylguanine-DNA methyltransferase (MGMT) gene promoter was determined in eight human cell lines by measuring chloramphenicol acetyltransferase activity in a reporter gene system. MGMT promoter activities in cells that do not express MGMT (Mer-) fell within the range of activities seen in cells that do express MGMT (Mer+). The promoter region contains 11 potential binding sites for the transcription factor Sp1, but no correlation was seen between cellular Sp1 protein and MGMT promoter chloramphenicol acetyltransferase activity. Because Mer- cells are not deficient in the factors needed for transcription of MGMT, we suggest that at least two mechanisms regulate MGMT expression. One suppresses MGMT mRNA and protein in Mer- cells, and another regulates the levels of constitutive expression in Mer+ cells. Sp1 is not a limiting factor in MGMT expression.
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PMID:A comparison of human O6-methylguanine-DNA methyltransferase promoter activity in Mer+ and Mer- cells. 142 89

In mammals, the apolipoprotein (apo) A-I gene is expressed predominantly in liver and intestine, while in avian species it is expressed in all tissues. Although liver and intestine are the major sites of chicken apoA-I mRNA synthesis, there are appreciable amounts of apoA-I mRNA in kidney, ovary/testes, brain, lung, skeletal, and heart muscle. In this study, the nucleotide sequences of the chicken apoA-I gene and its 5' flanking region, as well as the sequences involved in the expression of this gene, have been determined. The gene spans 1.5 kilobases and contains 4 exons and 3 introns, closely resembling the mammalian apoA-I gene. To determine the sequences involved in the expression of the chicken apoA-I gene, plasmid constructs containing serial deletions of the 5' flanking region of the chicken apoA-I gene fused to the bacterial chloramphenicol acetyltransferase (CAT) gene were transfected in human hepatoma (HepG2), colon carcinoma (Caco2), epithelial (Hela), mouse embryonal fibroblast (NIH3T3) cells, and quail myoblasts (QMLA29). The shortest deletion construct, containing 60 bp of the 5' upstream region, was sufficient for maximal transcriptional activity in all cell lines tested. This region contains a short sequence (nucleotides -60 to -54) that is highly conserved in birds and mammals, and an Sp1 binding site. Although the sequence between nucleotides -232 and -101 of the 5' region of the chicken apoA-I gene is partially homologous to the hepatic cell-specific enhancer of the mammalian apoA-I gene (located between nucleotides -222 and -110 upstream of the human apoA-I gene transcription start site), this chicken sequence is transcriptionally inactive in HepG2 cells. These results suggest that differences in the cis-acting regulatory elements of the apoA-I gene play a fundamental role in determining the differences in the tissue-specific expression of this gene in avian and mammalian species.
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PMID:Evolutionary distinct mechanisms regulate apolipoprotein A-I gene expression: differences between avian and mammalian apoA-I gene transcription control regions. 151 10


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