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)

The level of fibronectin (FN) gene transcription in resting rat 3Y1 cells is very high but decreases steeply after growth stimulation by serum or by the induction of E1A expression. To study the mechanism of this E1A-mediated down-regulation, the 5' flanking regions of the FN gene with various deletions and substitutions were fused to the Escherichia coli chloramphenicol acetyltransferase (CAT) gene and introduced into resting 3Y1 cells with E1A expression plasmids. The results indicate that the G10 stretch located from nucleotide position -239 to -230 and two GC boxes from position -105 to -95 and position -54 to -44 are the primary E1A-responsive elements for repression of the FN gene. Two GC boxes also contain a G10 stretch that is interrupted by the presence of an internal C residue. These sequences overlap with the Sp1 motif GGGCGG. Substitution of the sequence GGGG with ATCC or CTTA in these G-rich sequences, leaving the Sp1 motif intact, completely abolished the E1A sensitivity of the promoter. Analysis of the E1A domains by using various E1A deletion mutants indicated that the domain for binding to the retinoblastoma susceptibility gene product (RB) is essential for efficient repression. These results suggest that the gene encoding a negative factor(s) binding to the three G-rich sequences in the FN promoter is repressed by RB in resting 3Y1 cells and derepressed by expression of E1A.
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PMID:E1A-responsive elements for repression of rat fibronectin gene transcription. 153 44

A plasmid carrying the 5'-flanking region (-1852 to +33 with respect to the transcription initiation site) of the mouse DNA polymerase beta gene fused with the chloramphenicol acetyltransferase (CAT) gene was cotransfected into mouse N18TG2 cells with adenovirus type 12 E1 genes-expressing plasmids. Expression of E1A gene products resulted in the elevation of the CAT expression by 3 to 7 folds, but that of E1B gene product was much less effective. RNase protection analysis revealed that the activation by E1A was at the transcription process. Both the 13S E1A and the 12S E1A activated the DNA polymerase beta gene promoter, indicating that the activation domain of E1A is in a common region(s) of 13S and 12S E1A products. The major target sequence of E1A was mapped within the 10 base pair-region (-30 to -20) of the DNA polymerase beta gene promoter, which overlapped with the palindromic sequence known as the ATF(CREB)/E4F-binding consensus. The results suggest that the palindromic sequence is essential for E1A-induced transcriptional activation of the mouse DNA polymerase beta gene.
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PMID:Activation of the mouse DNA polymerase beta gene promoter by adenovirus type 12 E1A proteins. 153 5

Antigen triggering of the T-cell receptor results in an accumulation of activated GTP-bound p21ras protein. To assess the role of ras protein in T-cell activation we have cotransfected the murine thymoma line EL4 with a construct capable of expressing a constitutively active, oncogenic form of Ha-ras and a reporter construct containing the human interleukin-2 promoter fused upstream of the bacterial gene for chloramphenicol acetyltransferase. We show that the ras oncoprotein contributes to interleukin-2 promoter activation. Its pattern of synergism with a calcium ionophore or the lymphokine interleukin-1 indicates that it replaces a signal mediated by protein kinase C. Interleukin-2 promoter activity in the presence of ras oncoprotein was inhibited by H7, a potent inhibitor of protein kinase C, but not by HA1004, an inhibitor of cyclic nucleotide-dependent kinase, suggesting that protein kinase C mediates the ras effect. In addition, we show that in these cells, expression of activated ras results in activation of a synthetic promoter containing several copies of an NF kappa B binding site.
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PMID:Interleukin-2 promoter activation in T-cells expressing activated Ha-ras. 153 20

Studies from our laboratory concerning regulation of calbindin include regulation by 1,25-dihydroxycholecalciferol [1,25(OH)2D3], receptor regulation as a possible mechanism for modulating calbindin's response to hormone, tissue specific regulation and regulation by factors other than 1,25(OH)2D3. With regard to receptor regulation, we found that the induction of calbindin mRNA in intestine and kidney by 1,25(OH)2D3 is not accompanied by a corresponding alteration in vitamin D receptor (VDR) mRNA in the vitamin D-deficient, low calcium rat. However, in the vitamin D-replete rat, administration of 1,25(OH)2D3 results in an induction of both calbindin and VDR mRNA in these tissues. These results suggest the presence of an inhibitor of 1,25(OH)2D3-mediated receptor up-regulation in the vitamin D-deficient, low calcium animal. Glucocorticoids can also regulate calbindin gene expression. Dexamethasone treatment (50 micrograms.100 g body weight-1.d-1 for 4 d) results in a 75% decrease in rat intestinal calbindin-D9k mRNA. This decrease may be related to the inhibition of intestinal calcium absorption previously observed after glucocorticoid administration. Kidney calbindin-D28k mRNA is unaffected by glucocorticoid treatment, indicating tissue specificity of the glucocorticoid response. To evaluate more precisely the means whereby 1,25(OH)2D3 and other modulators can influence calbindin gene expression, we isolated the chromosomal gene for calbindin-D28k by screening a mouse genomic library in cosmid. Ros 17/2.8 cells were transfected with recombinant plasmids in which the mouse calbindin promoter is fused to the reporter gene encoding chloramphenicol acetyltransferase. Deletion studies have enabled us to identify sequence elements in the mouse calbindin-D28k gene that confer basal activation and a hormone inducible response.
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PMID:Molecular aspects of the calbindins. 154 30

We cloned, sequenced and characterized a promoter region of the mouse homologue of the Alzheimer's disease amyloid precursor protein (APP)-encoding gene. The promoter region is highly homologous to that of the human APP (hAPP) gene. It has a high G+C content, lacks typical 'TATA' and 'CAAT' boxes, and contains possible binding sites for AP-1, heat-shock factor, Sp1 and AP-4. The promoter region was fused with the cat reporter gene, and the fusion genes were transfected to both the NB41A3 (mouse neuroblastoma) and L-cell lines. The promoter activity was monitored by chloramphenicol acetyltransferase (CAT) activity in a transient expression assay. The promoter was equally active in both cell lines. The deletion analysis revealed that there existed a negative regulatory element(s) between -153 and -100 bp and a positive element(s) between -100 and -37 bp. The negative element was shown to suppress the transcriptional activity of heterologous simian virus 40 promoter. DNase I footprinting experiments revealed that three nuclear protein-binding sites existed in the regulatory region, one in the negative and two in the positive regulatory regions. Gel retardation assay showed that Sp1 was one of the factors binding to the positive regulatory region. A nuclear factor binding to the negative regulatory region seemed to be missing in brain.
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PMID:Positive and negative regulatory elements for the expression of the Alzheimer's disease amyloid precursor-encoding gene in mouse. 155 68

Human selenium-dependent glutathione peroxidase (hGPx1) (EC 1.11.1.9) is thought to be involved in many critical cellular functions as a result of its role in glutathione-mediated reduction of toxic peroxides, and it is implicated as a mechanism of resistance against oxygen free radicals. Previous studies have demonstrated that the gene encoding hGPx1 (hgpx1) is more highly expressed in multidrug-resistant AdrR MCF-7 human breast cancer cells than in the parental WT MCF-7 cell line. In order to further study the transcriptional regulation of hgpx1, we have cloned the genomic hgpx1 gene and determined its nucleotide sequence. The 2550-base pair (bp) 5'-flanking sequence of hgpx1 contained the terminal 511 bp of the 3' end of a previously reported rhoH12 cDNA (Yeramian, P., Chardin, P., Madaule, P., and Tavitian, A. (1987) Nucleic Acids Res. 15, 1989), a ras-related oncogene. Further downstream from rhoH12, but before the start of transcription of hgpx1, RNase protection analysis revealed a transcribed sequence of at least 270 bp which we have called mid. RNA transcripts homologous to both rhoH12 (1.8 and 1.5 kilobase pairs (kb)) and mid (1.8 kb) are also more highly expressed in AdrR MCF-7 cells than in WT MCF-7 cells. We screened an AdrR MCF-7 cDNA library with the mid sequence and isolated a partial cDNA clone which contains both mid and rhoH12 sequences and is colinear with the genomic sequence which extends from 10 bp 3' to the rhoH12 stop codon to 810 bp 5' to the start of transcription of hgpx1. The start of transcription of hgpx1 in AdrR MCF-7 cells was determined by primer extension analysis. The promoter and 2 kb of the 5'-flanking sequence of hgpx1 was fused to the bacterial chloramphenicol acetyltransferase gene (hGPx1-CAT1). Analysis of deletion constructs of hGPx1-CAT1 revealed three possible cis-acting regulatory regions. The transcriptional regulation of hgpx1 was examined using the hGPx1-CAT hybrid genes and nuclear run-on studies. We found no evidence that increased mRNA transcript formation could account for different levels of hgpx1 RNA either in different breast cancer cell lines or in response to selenium.
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PMID:Structure and function of the 5'-flanking sequence of the human cytosolic selenium-dependent glutathione peroxidase gene (hgpx1). 155 8

To analyze the mechanism of the cell type-specific expression of protein kinase C beta (PKC beta), we isolated the 5'-portion of the human gene for PKC beta and identified multiple positive and negative regulatory sequences that regulate its transcription. S1 nuclease mapping as well as primer extension analysis of the 5'-end of the PKC beta mRNA identified a putative transcriptional initiation site (position +1) 484 base pairs (bp) upstream of the first ATG codon. The 5'-upstream sequence contains a CCAAT sequence at position -110, but no TATA box. The transcriptional activities of various 5'-deletion mutants of the PKC beta gene upstream region, fused to the chloramphenicol acetyltransferase structural gene, were examined in terms of chloramphenicol acetyltransferase expression after transfection into three kinds of rodent cell lines: P19 and GH4C1, which are positive for the expression of PKC beta mRNA; and 3Y1, which is negative. Mutants containing a 5'-flanking sequence longer than 1.9 kilobases (kb) showed chloramphenicol acetyltransferase activities of the same order as the expression of the endogenous gene. This indicates that this region contains sequences regulating the cell-type specificity of PKC beta gene expression and that the specificity is determined at least partially at the level of transcription. The 1.9-kb sequence contains at least three positive elements: P1 (-56 to -234 bp), P2 (-234 to -411 bp), and PN (-1.4 to -1.9 kb). PN is active only in P19 cells, P1 in GH4C1 and P19 cells, and P2 in all three cell lines. In addition to these positive elements, there are negative elements: N1 (-411 to -674 bp), which is active in all three cell lines; and PN, which is active only in GH4C1 cells. These results suggest the presence of multiple trans-acting factors that act on these positive and negative cis-acting elements and regulate the cell type-specific expression of the PKC beta gene.
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PMID:Positive and negative regulation of the transcription of the human protein kinase C beta gene. 155 24

To study the molecular basis of tissue-specific expression of the GLUT4/muscle-fat facilitative glucose transporter gene, we generated lines of transgenic mice carrying 2.4 kilobases of the 5'-flanking region of the human GLUT4 gene fused to a chloramphenicol acetyltransferase (CAT) reporter gene (hGLUT4[2.4]-CAT). This reporter gene construct was specifically expressed in tissues that normally express GLUT4 mRNA, which include both brown and white adipose tissues as well as cardiac, skeletal, and smooth muscle. In contrast, CAT reporter activity was not detected in brain or liver, two tissues that do not express the GLUT4 gene. In addition, the relative levels of CAT mRNA driven by the human GLUT4 promoter in various tissues of these transgenic animals mirrored those of the endogenous mouse GLUT4 mRNA. Since previous studies have observed alterations in GLUT4 mRNA levels induced by fasting and refeeding (Sivitz, W. I., DeSautel, S. L., Kayano, T., Bell, G. I., and Pessin, J. E. (1989) Nature 340, 72-74), the regulated expression the hGLUT4[2.4]-CAT transgene was also assessed in these animals. Fasting was observed to decrease CAT activity in white adipose tissue which was super-induced upon refeeding. These alterations in CAT expression occurred in parallel to the changes in endogenous mouse GLUT4 mRNA levels. Although CAT expression in skeletal muscle and brown adipose tissue was unaffected, the endogenous mouse GLUT4 mRNA was also refractory to the effects of fasting/refeeding in these tissues. These data demonstrate that 2.4 kilobases of the 5'-flanking region of the human GLUT4 gene contain all the necessary sequence elements to confer tissue-specific expression and at least some of the sequence elements controlling the hormonal/metabolic regulation of this gene.
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PMID:Expression and regulation of the human GLUT4/muscle-fat facilitative glucose transporter gene in transgenic mice. 160 40

The effect of the treatment of HeLa cells with a tumor-promoting phorbol ester, 12-o-tetradecanoyl-phorbol-13-acetate (TPA) on the expression of the genes for the calpain family has been examined. Among the mRNAs for the calpain family, only the mRNA for the large subunit of human m-calpain (calpain mL) was specifically induced by treatment of cells with TPA, suggesting its specific function in response to cellular stimuli. The effect of TPA on the expression of the calpain mL gene was further examined using fusion genes containing the promoter/enhancer region of the calpain mL gene fused upstream of the bacterial chloramphenicol acetyltransferase (CAT) gene, showing that the promoter/enhancer sequence of the calpain mL gene contains a cis-acting element which responds to TPA and activates transcription of the downstream sequence.
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PMID:Transcriptional activation of the gene for the large subunit of human m-calpain by 12-o-tetradecanoyl-phorbol-13-acetate. 161 29

Abbreviated purine nucleoside phosphorylase (PNP) genes were engineered to determine the effect of introns on human PNP gene expression. PNP minigenes containing the first intron (complete or shortened from 2.9 kb down to 855 bp), the first two introns or all five PNP introns resulted in substantial human PNP isozyme expression after transient transfection of murine NIH 3T3 cells. Low level human PNP activity was observed after transfection with a PNP minigene containing the last three introns. An intronless PNP minigene construct containing the PNP cDNA fused to genomic flanking sequences resulted in undetectable human PNP activity. Heterogeneous, stable NIH 3T3 transfectants of intron-containing PNP minigenes (verified by Southern analysis), expressed high levels of PNP activity and contained appropriately processed 1.7 kb message visualized by northern analysis. Stable transfectants of the intronless PNP minigene (40-45 copies per haploid genome) contained no detectable human PNP isozyme or mRNA. Insertion of the 855 bp shortened intron 1 sequence in either orientation upstream or downstream of a chimeric PNP promoter-bacterial chloramphenicol acetyltransferase (CAT) gene resulted in a several-fold increase in CAT expression in comparison with the parental PNP-CAT construct. We conclude that human PNP gene expression at the mRNA and protein level is dependent on the presence of intronic sequences and that the level of PNP expression varies directly with the number of introns included. The disproportionately greatest effect of intron 1 can be explained by the presence of an enhancer-like element retained in the shortened 855 bp intron 1 sequence.
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PMID:Intron requirement for expression of the human purine nucleoside phosphorylase gene. 162 Jun 16


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