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)

EBV infection of B cells induces the B cell activation Ag, CD23 (Fc epsilon RII). CD23 remains constitutively expressed at high levels in all EBV-immortalized B cells and likely plays an important role in the initiation and maintenance of immortalization by EBV. By utilizing an EBV-negative Burkitt's lymphoma line (BJAB) and EBV-positive sublines derived from it by in vitro infection, we have examined the molecular mechanisms involved in the regulation of CD23 by EBV. By nuclear runoff analysis, we have found that induction of CD23 is mediated by transcriptional activation that occurs in the presence of the transformation-competent B958 virus but not in the presence of the nontransforming P3HR-1 strain of EBV. To identify EBV-responsive transcriptional regulatory elements of CD23, we have performed reporter gene assays using plasmids containing fragments of the CD23 gene derived from its 5' terminus and adjacent flanking region transfected into EBV-positive and -negative BJAB lines. We have identified a 534-bp fragment of the gene which enhances transcription from a heterologous promoter (SV40) and reporter gene (chloramphenicol acetyltransferase) only in the presence of transformation-competent strains of EBV. Deletion of 144 bp of intron 1 from the 3' end of this fragment results in loss of EBV-responsive enhancer activity. The finding of an EBV-responsive enhancer element of CD23 is supported by mobility shift assays that demonstrated the formation of specific DNA-protein complexes between nuclear protein from transforming EBV-positive cells and the 144-bp intron sequence. These studies suggest that the transcriptional activation of CD23 by transforming strains of EBV involves regulatory elements that are located within the first intron of the gene.
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PMID:Transcriptional regulation of the human IgE receptor (Fc epsilon RII/CD23) by EBV. Identification of EBV-responsive regulatory elements in intron 1. 131 50

Factor X is a vitamin K-dependent glycoprotein that plays an essential role in both the intrinsic and extrinsic pathways of blood coagulation. Studies on a recombinant lambda phage containing the 5'-flanking region of the human factor X gene showed that the factor X gene was linked to and was located at the 3' end of the factor VII gene: the initiation codon of the factor X gene was 2823 base pairs (bp) downstream from the polyadenylation site of the factor VII gene. This 2.8-kilobase intergenic region, and progressively deleted fragments of it, was fused to the chloramphenicol acetyltransferase gene, and transient expressions in HepG2 cells, human fibroblasts, and Chinese hamster ovary cells were measured. A liver-specific promoter element, FXP1-binding site, essential for hepatocyte-specific transcription was identified. This promoter sequence, further localized to -63 to -42 bp in DNase I footprint studies, was homologous to LF-A1 or hepatic nuclear factor-4 recognition sequence and was equally functional in the normal and inverse orientations. FXP1 site bound to nuclear protein(s) from HepG2 cells and complex formation was partially abolished by the presence of duplex oligonucleotides containing liver factor-A1 or hepatic nuclear factor-4-binding sequences. Two additional positive elements located upstream of the promoter region, spanning from -215 to -149 bp (FXP2 site), and -457 to -351 bp (FXP3 site), were also established by reporter gene assays.
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PMID:Liver-specific expression of the gene coding for human factor X, a blood coagulation factor. 131 96

We previously isolated and sequenced the 5'-flanking region of the mouse CD14 (mCD14) gene (Matsuura, K., Setoguchi, M., Nasu, N., Higuchi, Y., Yoshida, S., Akizuki, S., and Yamamoto, S. (1989) Nucleic Acids Res. 17, 2132). To define the regulatory elements that control expression of the mCD14 gene, we analyzed the structure of the 5' end of the gene, including a region further upstream of that determined previously. Sequentially 5'-deleted, chimeric, and point mutated clones were tested for the ability to stimulate chloramphenicol acetyltransferase. An 8-base pair sequence, TGATTCAC, at position -255, which resembled the consensus sequence of the 12-O-tetradecanoylphorbol-13-acetate-responsive element (TRE), enhanced the expression of the chloramphenicol acetyltransferase gene in macrophage (aHINS-B3) and non-macrophage (glioblastoma G203 and myeloma NS1) cells. The enhancing ability of the TRE-like sequence (TLS), however, was markedly reduced in G203 cells but not in aHINS-B3 cells when the TLS was followed by the sequence immediately downstream. The TLS and sequence immediately downstream were capable of binding nuclear proteins which were unique to aHINS-B3 cells and macrophages, suggesting that these unique protein regulate the specific expression of the mCD14 gene. Binding of AP-1 to the TLS was also found in aHINS-B3 and G203 cells. Although it is uncertain whether AP-1 is involved in expression of the mCD14 gene, the effect of AP-1 in non-macrophage cells was inhibited by a nuclear protein which binds to the sequence immediately downstream of the TLS.
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PMID:Identification of a tissue-specific regulatory element within the murine CD14 gene. 138 28

Basal expression of a chimeric gene (pMHO4CAT) consisting of approximately 7 kilobase pairs (kbp) of the 5'-flanking region of the mouse heme oxygenase-1 (HO-1) gene fused to the bacterial chloramphenicol acetyltransferase gene is 2- to 10-fold greater than that of an analogous construct containing only 1287 bp of the 5'-flanking region (pMHO1CAT) in transiently transfected cultured cells. The enhancer activity has been localized to a 268-base pair (bp) fragment positioned approximately 4 kilobase pairs upstream of the transcription initiation site. This fragment contains two high affinity protein binding sites, regions A and B, as determined by DNase I protection assays using nuclear protein extracts from rat C6 glioma cells. Both sites include core sequence elements, TGAGTCA (region A) and TGTGTCA (region B), that resemble the consensus binding site, TGA(G/C)TCA, of the Jun/Fos (AP-1) family of transcription factors. Purified, bacterially expressed AP-1 (c-Jun homodimer) specifically binds to both elements, exhibiting greater affinity for the region A motif. The expression of pMHO4CAT, but not of pMHO1CAT, is stimulated by the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA), and the 268-bp enhancer fragment confers TPA inducibility and c-Jun/c-Fos transactivation to the heterologous SV40 promoter. These functions are mediated by the AP-1 binding sites as multiple copies of the region A motif also confer TPA induction and c-Jun/c-Fos transactivation upon a heterologous promoter.
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PMID:Distal AP-1 binding sites mediate basal level enhancement and TPA induction of the mouse heme oxygenase-1 gene. 140 Apr 99

Carnitine palmitoyltransferase (CPT) regulates the flux of long-chain fatty acids into the mitochondria for subsequent beta-oxidation. A 485 bp segment of the promoter for the gene encoding the 68 kDa CPT was isolated from a rat lambda DASH genomic library using the polymerase chain reaction. The promoter contained a consensus binding sequence for CREB (cyclic AMP response element binding protein) at -153 to -166, and for C/EBP alpha (CCAAT/enhancer binding protein) at -115 to -128. DNAase I footprinting using proteins isolated from rat liver nuclei indicated the presence of several regions of nuclear protein binding, most notably at -95 to -130, at -273 to -295, and at a wide region encompassing -395 to -465. DNAase I footprinting studies with purified CREB and C/EBP alpha confirmed that protein binding to DNA occurred at the sites predicted by the consensus sequences. The segment containing 481 bp of 5' flanking sequence plus 181 bp of untranslated mRNA was ligated to the structural gene for chloramphenicol acetyltransferase (CAT). When this plasmid was transfected into Hep G2 cells, CAT activity was stimulated 7-fold by addition of 1 mM-8-bromo-cyclic AMP (8-Br-cAMP) or co-transfection of the expression vector coding for the catalytic subunit of protein kinase A (PKA). The ability of several known second messengers and transcription factors to stimulate transcription of 68 kDa CPT promoter-CAT reporter was tested in co-transfection experiments. 68 kDa CPT promoter-CAT reporter transcription activity was stimulated 7-fold by addition of 8-Br-cAMP, and this induction was depressed 50% by the addition of phorbol esters. When the 68 kDa CPT promoter-CAT reporter was co-transfected with an expression vector for CREB or C/EBP alpha, transcription was increased 3- and 10-fold respectively. 8-Br-cAMP caused an additional 8-fold induction in the presence of each factor to yield 25- and 80-fold induction respectively. Co-transfection of the expression vector for c-jun also increased the CAT activity driven by the 68 kDa CPT promoter, while co-transfection with the expression vector for c-fos had no effect. When expression vectors for both c-jun and c-fos were co-transfected with the 68 kDa CPT promoter, c-fos depressed the induction seen with c-jun alone.
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PMID:Isolation and characterization of the promoter for the gene coding for the 68 kDa carnitine palmitoyltransferase from the rat. 825 Aug 54

Retinoic acid (RA) and epidermal growth factor (EGF) regulate growth and differentiation of epithelial cells. RA has both direct and indirect effects on gene expression. Direct effects result from modulation of the transcriptional activity of genes, which contain RA response elements (RARE) recognized by trans-acting nuclear RA receptors (RARs). A second indirect mechanism for the modulatory effects of RA is by the induction or repression of growth factors and growth factor receptors. There is evidence for functional interactions between RA and the EGF receptor (EGFR). RA enhances the proliferative response of cultured keratinocytes to EGF, increases the number of EGFRs on the surface of some cells, and induces EGFR promoter activity in most cells. In contrast, immunoprecipitation, Northern blot, and nuclear run-on analysis described in this paper show that RA suppresses EGFR synthesis at the transcriptional level in human epidermoid carcinoma ME180 cells. Deletion analysis of EGFR gene promoter mutants linked to the chloramphenicol acetyltransferase gene revealed the existence of a region of the promoter, -771 to -384, which is responsive to RA. Gel retardation data indicated that a cell-type nuclear protein which binds to this novel element is suppressed by RA in a dose-dependent manner. This decrease coincides with a decreased steady-state level of RAR-gamma mRNA. These data strongly suggest that the EGFR promoter is regulated by RAR-gamma, which itself is under the control of RA. Other cell-specific trans-acting factors may be involved in this regulation.
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PMID:Transcriptional control of epidermal growth factor receptor by retinoic acid. 151 68

The c-myb protooncogene, which is preferentially expressed in hematopoietic cells at the G1/S boundary of the cell cycle, encodes a transcriptional activator that functions via DNA binding. The regulatory mechanisms governing this specific pattern of expression are not fully understood, although human c-myb expression appears to be positively autoregulated via myb-binding sites in the 5'-flanking region of the c-myb gene (Nicolaides, N. C., Gualdi, R., Casadevall, C., Manzella, L., and Calabretta, B. (1991) Mol. Cell. Biol. 11, 6166-6176). To determine the contribution of other transcription regulators such as JUN family members in the control of c-myb expression, transient expression assays were carried out which revealed a 6- to a 15-fold enhancement by c-Jun and JunD, but not JunB, in chloramphenicol acetyltransferase reporter gene expression driven by different segments of the human c-myb 5'-flanking region. An Ap1-like element located at nucleotide -149 from the c-myb initiation site appears to be required for this transactivation upon binding to a nuclear protein complex containing c-Jun and JunD, since site-directed mutations of this Ap1-like element abolished c-Jun and JunD binding and transactivation. Exposure of phytohemagglutinin-stimulated peripheral blood mononuclear cells to c-jun and junD antisense oligodeoxynucleotides resulted in a 46 and 43% inhibition of T-lymphocyte proliferation that was accompanied by a decrease in c-myb mRNA levels as compared with sense-treated cultures. Because T-lymphocytes induced to proliferate express c-jun and junD before c-myb, these data suggest a mechanism whereby c-Jun and JunD contribute to the transcriptional activation of c-myb that, in turn, is maintained at the G1/S transition and during S phase by positive autoregulation.
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PMID:The Jun family members, c-Jun and JunD, transactivate the human c-myb promoter via an Ap1-like element. 152 86

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

The herpes simplex virus type 1 (HSV-1)-mediated transactivation of human immunodeficiency virus type 1 (HIV-1) provirus was studied in cell lines containing either integrated tat-defective HIV-1 provirus (HNHIVdt4 cells) or the tat-defective HIV-1 provirus, and a plasmid in which the expression of human alpha 2 interferon (HuIFN-alpha 2) was under the control of the HIV-1 long terminal repeat (LTR) (HNHIV alpha 1 cells). In both cell lines, transcription of the HIV-1 provirus was below the limits of detection, but it could be induced effectively by transfection with a HIV-1 tat-expression plasmid. In HNHIV alpha 1 cells, HuIFN-alpha 2 was induced concomitantly with HIV-1 provirus, although these cells synthesized only low levels of IFN constitutively. In contrast, infections with HSV-1 activated transcription of HIV-1 provirus only in HNHIVdt4 cells but not in HNHIV alpha 1 cells. Similarly in a transient expression assay, HSV-1 up-regulated expression of a HIV LTR-CAT (chloramphenicol acetyltransferase gene) plasmid in HNHIVdt4 but not in HNHIV alpha 1 cells. No major differences could be detected in the expression of HSV-1 immediate-early (IE) genes IE175 and IE110 (which are essential for the activation of HIV-1 LTR) in HNHIVdt4 and HNHIV alpha 1 cells to account for the inability of HSV-1 to induce HIV-1 in HNHIV alpha 1 cells. However, major differences were observed in the binding pattern of NF-kappa B-specific nuclear proteins to the enhancer region of the HIV-1 LTR: whereas binding of the 45-kDa NF-kappa B-specific nuclear protein was detected in nuclear extracts from HNHIVdt4 cells, no protein binding was seen in extracts from HNHIV alpha 1 cells. These results suggest an alternate mechanism by which IFN may alter the expression of cellular and viral genes.
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PMID:Inhibition by interferon of herpes simplex virus type 1-activated transcription of tat-defective provirus. 171 35

Expression of prostate-specific antigen (PA) mRNA was tested at various time periods after incubation of the human prostate tumor cell line LNCaP with the synthetic androgen R1881. Androgen-stimulated expression was observed within 6 h after addition of R1881 to the cells. Run-on experiments with nuclei isolated from LNCaP cells showed that expression of the PA gene could be regulated by R1881 on the level of transcription. DNase I footprints of the promoter region of the PA gene (-320 to +12) with nuclear protein extracts from LNCaP cells showed at least four protected regions. The protected areas include the TATA-box, a GC-box sequence, and a sequence AGAACAgcaAGTGCT at position -170 to -156, which closely resembles the reverse complement of the consensus sequence GGTACAnnnTGTTCT for binding of the glucocorticoid receptor and the progesterone receptor. Fragments of the PA promoter region were cloned in front of the chloramphenicol acetyltransferase (CAT) reporter gene and cotransfected with an androgen receptor expression plasmid into COS cells in a transient expression assay. CAT activity of COS cells grown in the presence of 1 nM R1881 was compared to untreated controls. A 110-fold induction of CAT activity was found if a -1600 to +12 PA promoter fragment was used in the construct. By further deletion mapping of the PA promoter a minimal region (-320 to -155) was identified as being essential for androgen-regulated gene expression. Mutation of the sequence AGAACAgcaAGTGCT (at -170 to -156) to AAAAAAgcaAGTGCT almost completely abolished androgen inducibility of the reporter gene constructs. One or more copies of the sequence AGAACAgcaAGTGCT cloned in front of a thymidine kinase promoter-CAT reporter gene confers androgen regulation to the reporter gene. These findings provide strong evidence for transcription regulation of the PA gene by androgens via the sequence AGAACAgcaAGTGCT. Interestingly, in addition to the AGAACAgcaAGTGCT element, an upstream region (-539 to -320) is needed for optimal androgen inducibility of the PA promoter.
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PMID:The promoter of the prostate-specific antigen gene contains a functional androgen responsive element. 172 87


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