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 examined the interaction of human immunodeficiency virus (HIV) and herpes group viruses. For this purpose, a chimeric plasmid (pLTR-CAT) was constructed in which the long terminal repeat (LTR) sequences derived from a molecular clone of HIV were fused to a bacterial chloramphenicol acetyltransferase gene (CAT). Transient expression assays in transfected tissue culture cells were used to monitor the activity of the LTR. Basal levels of CAT activity were measured in HeLa and human lung fibroblast (HLF) cells transfected with pLTR-CAT. When HeLa or HLF cells transfected with pLTR-CAT were infected with herpesviruses, HIV LTR-directed expression of the CAT gene was detected. An enhancement of the HIV LTR-directed expression of CAT was observed for herpes simplex virus (HSV)-1 and HSV-2, cytomegalovirus and varicella zoster virus. Enhanced CAT expression directed by the LTR was also shown by cotransfection of recombinant plasmids containing two non-overlapping regions of HSV-1, a fragment from HSV-2 which is non-colinear with the regions used from HSV-1, the immediate early gene of pseudorabies virus and the adenovirus early gene EIA. HIV LTR-directed expression may be a useful model for studying the effects on HIV of various infectious agents known to be present in individuals with AIDS or HIV infection.
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PMID:Transactivation of human immunodeficiency virus by herpesviruses. 283 May 74

We constructed a series of mutations that delete sequences in the promoter region of the early-region IV (EIV) promoter of adenovirus type 5. We fused these promoter mutations to the coding sequences of either the chloramphenicol acetyltransferase or the dihydrofolate reductase (DHFR) gene and tested the ability of a cotransfected EIa gene to stimulate EIV expression. All of the mutations tested were stimulated in these assays, implying that no specific sequence is required for stimulation. Two mutant promoters, deleted for either the TATA box or the region residing between -39 and -177 upstream from the cap site of EIV mRNA, did show a reduced level of stimulation by the EIa products. To assess the effects of the EIA gene products on expression from an EIV promoter integrated into the chromosome, we isolated CHO cell lines containing EIV-DHFR chimeric genes. After introduction of the EIa gene with a second selectable marker, expression from all mutant EIV-DHFR genes was increased. Surprisingly, one mutant promoter, deleted for sequences between -39 and -177, lost the ability to respond to the EIa region on passage of cells, although deletions in any part of the region still retained this ability. These results demonstrate that multiple elements residing between -39 and -177 in the EIV promoter are necessary to maintain susceptibility of the integrated promoter to regulation.
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PMID:A specific domain of the adenovirus EIV promoter is necessary to maintain susceptibility of the integrated promoter to EIA transactivation. 296 81

A molecular dissection of the adenovirus EIIA early (E) promoter was undertaken to study the sequence elements required for transcription and to examine the nucleotide sequences, if any, specific for its trans-activation by the viral pre-early EIA gene product. A chimeric gene in which the EIIA-E promoter region fused to the coding sequences of the bacterial chloramphenicol acetyltransferase (CAT) gene was used in transient assays to identify the transcriptional control regions. Deletion mapping studies revealed that the upstream DNA sequences up to -86 were sufficient for the optimal basal level transcription in HeLa cells and also for the EIA-induced transcription. A series of linker-scanning (LS) mutants were constructed to precisely identify the nucleotide sequences that control transcription. Analysis of these LS mutants allowed us to identify two regions of the promoter that are critical for the EIIA-E transcription. These regions are located between -29 and -21 (region I) and between -82 and -66 (region II). Mutations in region I affected initiation and appeared functionally similar to the "TATA" sequence of the commonly studied promoters. To examine whether or not the EIIA-E promoter contained DNA sequences specific for the trans-activation by the EIA, the LS mutants were analyzed in a cotransfection assay containing a plasmid carrying the EIA gene. CAT activity of all of the LS mutants was induced by the EIA gene in this assay, suggesting that the induction of transcription of the EIIA-E promoter by the EIA gene is not sequence-specific.
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PMID:Adenovirus EIIA early promoter: transcriptional control elements and induction by the viral pre-early EIA gene, which appears to be sequence independent. 385 77

Although 17 beta-estradiol (E2) replacement therapy has been shown to be effective in treating postmenopausal osteoporosis, the underlying mechanism remains unclear. The presence of low levels of functional endogenous estrogen receptor (ER) in some osteoblastic cells has been demonstrated, and the suggestion that the abundance of ER may be rate-limiting in the action of E2 on these cells has been made. To study the mechanism of ER in regard to E2-mediated effects, we stably transfected a human osteosarcoma cell line, SaOS-2, with an expression vector, pMV-7-ER, containing the human ER gene. We characterized six of the stably transfected clones. One of the stable clones, SaOS-2-ER, expressed extra copies of ER genes integrated into the genome as detected by Southern blot analysis, showed a significantly increased level of ER mRNA by RT-PCR, and contained an increased level of ER cytosolic protein as detected by an ER-specific EIA. The overexpressed ER was functional and sensitive to E2 in a dose-dependent fashion after transient transfection with a vector containing an estrogen response element (ERE) linked to a chloramphenicol acetyltransferase (CAT) reporter gene. Scatchard analysis revealed a single high-affinity binding site with a Kd similar to values obtained for the ER in MCF-7 breast cancer cells. These SaOS-2-ER cells had altered osteoblast phenotypic features including growth inhibition, decreased basal alkaline phosphatase activity, and decreased IL-6 expression and secretion. In response to E2, a greater than 2-fold increase in TGF-beta 1 mRNA was quantitatively measured in these ER-overexpressing osteoblasts. These cells may provide a sensitive and unique model for understanding the mechanism of E2 and ER in overall bone metabolism.
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PMID:Generation and characterization of a human osteosarcoma cell line stably transfected with the human estrogen receptor gene. 763 12

In previous studies we demonstrated that the E1A DNA and proteins of group C adenovirus are present in excess in the lungs of patients with chronic obstructive pulmonary disease (COPD). Because adenovirus EIA gene products are known to regulate the expression of many genes by interacting with cellular transcription factors, we postulated that E1A enhances the production of inflammatory mediators and exacerbates the inflammatory process in smokers' lungs. We reported that LPS-induced ICAM-1 expression in A549 cells is upregulated by E1A. In the current study we investigated whether this regulation is mediated through the ICAM-1 promoter. A549 cells and primary human bronchial epithelial (HBE) cells were transiently cotransfected with a plasmid containing the ICAM-1 enhancer-promoter linked to the chloramphenicol acetyltransferase (CAT) reporter gene (pBS-CAT-P) and either a plasmid carrying the adenovirus 5 E1A gene (pE1Aneo) or a control plasmid (pneo). To compare the effect of transient versus stable E1A expression on the activity of this promoter, we also transiently transfected stable E1A-expressing A549 cells with pBS-CAT-P. Transient cotransfection of pE1Aneo and pBS-CAT-P had no effect on basal ICAM-1 promoter activity in A549 or HBE cells. After stimulation of A549 cells with TNF-alpha, IFN-gamma, or LPS, promoter activity was increased by two- to threefold in the presence of adenovirus EIA. In HBE cells, on the other hand, E1A repressed the ICAM-1 promoter after stimulation with IFN-gamma and LPS with little change after TNF-alpha stimulation. In stable E1A transfectants, ICAM-1 promoter activity was 2 to 2.5 times higher than in control transfectants with or without stimulation with TNF-alpha or LPS. These findings suggest that EIA can modulate the activity of the ICAM-1 promoter in lung epithelial cells and this modulation is different in cells of alveolar origin compared to bronchial epithelial cells.
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PMID:Effect of adenovirus E1A on ICAM-1 promoter activity in human alveolar and bronchial epithelial cells. 1094 78