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)

Hepatocyte growth factor (HGF) is a potent mitogen for hepatocytes; however, in certain human hepatoma cell lines, the growth is inhibited by HGF. In the present study, the effect of HGF on the alpha-fetoprotein (AFP) gene expression was analyzed in PLC/PRF/5 human hepatoma cells. HGF did not inhibit cell proliferation, but dose-dependently suppressed AFP secretion at the concentrations of 10 ng/ml or less. By Northern blot analysis, the levels of AFP mRNA were suppressed by HGF, whereas the levels of beta-actin mRNA used as a control did not show any significant changes. In the transient chloramphenicol acetyltransferase plasmid transfection assays, the AFP promoter activity was repressed by HGF, in contrast, the AFP enhancer activity was not affected by HGF. These results suggest that the AFP gene expression is down-regulated by HGF through the suppression of its promoter activity in human hepatoma cells.
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PMID:Hepatocyte growth factor down-regulates the alpha-fetoprotein gene expression in PLC/PRF/5 human hepatoma cells. 128 Apr 22

A variety of gene constructs containing carp beta-actin regulatory sequences were tested for their ability to drive transient expression of the chloramphenicol acetyltransferase reporter gene in 3 fish cell lines: carp epithelial cells (EPC), rainbow trout hepatoma cells (RTH149), and rainbow trout fibroblasts (RTG2). The constructs showed a wide variation in their levels of expression, and there were significant differences in the effects of transcriptional elements in the 3 cell lines. Sequences that enhanced expression in EPC cells were inhibitory in RTH149 and RTG2 cells. All cell lines exhibited the presence of nuclear trans-acting factors that could bind to implicated transcriptional control elements. On the basis of the cell culture results, selected constructs were examined for activity in early carp development. Constructs active in embryos and fry were further tested and found to express transgenes in adult fish.
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PMID:Selection of promoters for gene transfer into fish. 130 23

In order to establish alternatives to the frequently used uterotropic assay with mice, defined estrogen-sensitive cell lines (MCF-7 cells and LeC-9 cells) were used to determine the estrogenic activities of purified compounds of vegetable origin (myco- and phytoestrogens) and zearalenone-contaminated forage cereals (wheat, barley and oats). In MCF-7 cells, a human breast cancer cell line, the induction of an estrogen-specific exoprotein served as a parameter of estrogenic activities. LeC-9 cells represent a genetically transformed cell clone derived from mouse L-cells. Here, hormone-like activities were measured by the expression of the bacterial chloramphenicol acetyltransferase (CAT) gene under the control of an estrogen-responsive element. Toxic effects affecting cell viability were monitored in this system by the expression of a second reporter gene (the bacterial beta-galactosidase gene controlled by the constitutive human beta-actin promoter). Relative estrogenic activities of myco- and phytoestrogens determined with both systems are concomitant, but higher as compared to the uterotropic assay with mice.
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PMID:Validation of two in vitro test systems for estrogenic activities with zearalenone, phytoestrogens and cereal extracts. 138 42

The promoter regions of the chicken skeletal muscle alpha-actin (alpha sk-actin) and the cytoplasmic beta-actin genes were linked to the bacterial chloramphenicol acetyltransferase (CAT) gene. Replication-competent retroviral vectors were used to introduce these two actin/CAT cassettes into the chicken genome. Chickens infected with retroviruses containing the alpha sk-actin promoter expressed high levels of CAT activity in striated muscle (skeletal muscle and heart); much lower levels of CAT activity were produced in the other nonmuscle tissues. In contrast, chickens infected with retroviruses containing the beta-actin promoter linked to the CAT gene expressed low levels of CAT activity in many different tissue types and with no discernible tissue specificity. Data are presented to demonstrate that the high levels of CAT activity that were detected in the skeletal muscle of chickens infected with the retrovirus containing the alpha sk-actin promoter/CAT cassette were not due to preferential infectivity, integration, or replication of the retrovirus vector in the striated muscles of these animals.
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PMID:Appropriate in vivo expression of a muscle-specific promoter by using avian retroviral vectors for gene transfer [corrected]. 163 16

The aberrant overexpression of interleukin 6 (IL-6) is implicated as an autocrine mechanism in the enhanced proliferation of the neoplastic cell elements in various B- and T-cell malignancies and in some carcinomas and sarcomas; many of these neoplasms have been shown to be associated with a mutated p53 gene. The possibility that wild-type (wt) p53, a nuclear tumor-suppressor protein, but not its transforming mutants might serve to repress IL-6 gene expression was investigated in HeLa cells. We transiently cotransfected these cells with constitutive cytomegalovirus (CMV) enhancer/promoter expression plasmids overproducing wt or mutant human or murine p53 and with appropriate chloramphenicol acetyltransferase (CAT) reporter plasmids containing the promoter elements of human IL-6, c-fos, or beta-actin genes or of porcine major histocompatibility complex (MHC) class I gene in pN-38 to evaluate the effect of the various p53 species on these promoters. Murine and human wt p53 derived from pCMVNc9 and pC53-SN3, respectively, strongly repressed the IL-6 (promoter position -225 to +13), c-fos (-711 to +42), beta-actin (-3400 to +912), and MHC (-528 to -38) promoters in serum-induced HeLa cells; additionally, IL-6 promoter/CAT transcription unit constructs induced by IL-1, phorbol ester, or pseudorabies virus were also repressed by wt human and murine p53. The murine transforming mutant p53 (pCMVc5) was less active in repressing the IL-6, c-fos, beta-actin, and MHC promoter constructs. The human p53 mutant derived from pC53-SCX3 was also less active than the wt protein in repressing the IL-6, c-fos, beta-actin, and MHC promoters, except that serum-induced IL-6/CAT expression was equally repressed by both human wt and mutant p53. In similar transient transfection experiments in HeLa cells, overexpression of the wt human retinoblastoma susceptibility gene product, RB, was found to repress the serum-induced IL-6 (-225 to +13), c-fos (-711 to +42), and beta-actin (-3400 to +912) promoters but not the PRV-induced IL-6 (-110 to +13) or the serum-induced MHC (-528 to -38) promoters. These observations identify transcriptional repression as a property of p53 and suggest that p53 and RB may be involved as transcriptional repressors in modulating IL-6 gene expression during cellular differentiation and oncogenesis.
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PMID:Repression of the interleukin 6 gene promoter by p53 and the retinoblastoma susceptibility gene product. 165 55

The antiviral/antiproliferative/antitumor properties of interferon (IFN) are potentiated by a febrile temperature (Heron, I., and Berg, K. (1978) Nature 274, 508-510; Fleischmann, W. R., Fleischmann, C. M., Jr., and Gindhart, T. D. (1986) Cancer Res. 46, 1722-1726; Groveman, D. S., Borden, E. C., Merritt, J. A., Robins, H. I., Steeves, R., and Bryan, G. T. (1984) Cancer Res. 44, 5517-5521). To investigate the role of 2',5'-oligoadenylate (2-5A) synthetase in linking temperature with these biological functions of IFN, antiviral activities and expression of the 2-5A synthetase gene were measured simultaneously in control and type I IFN-treated HL-60 and WISH cells at the selected elevated temperature of 39.5 degrees C +/- 0.5 degrees C (herein referred to as hyperthermia). In both cell lines, the IFN-mediated antiviral effect was enhanced 3-10-fold. Concurrently, enzymatic assays and immunoblot analyses with an anti-40-kDa synthetase antibody clearly gave a 2-3-fold increase of synthetase above that observed at the normal cell culture temperature (37 degrees C). These results suggest that potentiation of 2-5A synthetase must partially account for the enhanced antiviral activity of IFN at the higher cell culture temperature. The supranormal elevation of 2-5A synthetase was accompanied by a parallel increase in the steady-state concentration of 2-5A synthetase mRNA, which is likely to contribute to the observed increase in enzyme level. Transient reporter gene expression studies using plasmid constructs carrying 2-5A synthetase gene promoter linked in tandem with chloramphenicol acetyltransferase showed that IFN-inducible chloramphenicol acetyltransferase activity was not influenced by hyperthermia, suggesting that transcription activation is an unlikely explanation for the observed 2-5A synthetase mRNA level increases. Messenger RNA stability assays showed that the half-life (t1/2) of 2-5A synthetase mRNA was extended from 2 to 4 h at 39.5 degrees C. Under identical conditions, the t1/2 of poly(A)+ RNA remained unchanged whereas the t1/2 of beta-actin mRNA was reduced. Taken together, these results are consistent with the interpretation that selective stabilization of 2-5A synthetase mRNA at the elevated temperature is a major factor contributing to the potentiation of antiviral activity of IFN by hyperthermia.
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PMID:Modulation of antiviral activity of interferon and 2',5'-oligoadenylate synthetase gene expression by mild hyperthermia (39.5 degrees C) in cultured human cells. 170 57

We have constructed a series of replication-competent retrovirus vectors to introduce and express gene cassettes in avian cells. To characterize these vectors, we inserted the coding sequences for the bacterial chloramphenicol acetyltransferase (CAT) gene linked to the chicken beta-actin gene promoter or the mouse metallothionein 1 gene promoter. In all cases, we found the structure of integrated proviruses to be stable during serial cell passage in vitro. Chloramphenicol acetyltransferase activity was detected biochemically and immunocytochemically in infected cells. Cassettes were inserted in the vectors in the same or in the opposite orientation with respect to viral transcription. Although both orientations were functional, the cassettes inserted in the forward orientation were usually expressed at higher levels than the corresponding backward constructions. The level of expression was strongly influenced by surrounding proviral sequences, particularly by the transcriptional enhancer elements within the retrovirus long terminal repeat sequences. Expression was higher with vectors that contained the polymerase (pol) region of the Bryan high-titer strain of Rous sarcoma virus. Inclusion of the Bryan pol region also improved vector replication in the chemically transformed quail fibroblast line QT6.
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PMID:Replication-competent retrovirus vectors for the transfer and expression of gene cassettes in avian cells. 204 Oct 92

Tubulointerstitial changes in the diabetic kidney correlate closely with the decline in glomerular filtration. In this study, we used a cell culture system of mouse proximal tubule epithelial cells to test the effects of glucose on cell growth, size, and matrix biosynthesis. [3H]thymidine incorporation was significantly inhibited in cells grown in 450 mg/dl glucose, compared with cells grown in 100 mg/dl glucose. The cells grown in the higher glucose concentration were slightly larger, their protein content and the total protein synthetic rate were significantly increased, and they secreted approximately twice as much procollagens type IV and type I. Concordantly, steady-state procollagen mRNA levels were also increased: 2.6-fold for the alpha 1(IV) and 2.2-fold for the alpha 2(I) procollagens. Additionally, nuclear run-off studies demonstrated that procollagen gene transcription rate was stimulated approximately 50%; beta-actin transcription rate was not altered. We used chloramphenicol acetyltransferase (CAT) reporter gene constructs to determine whether the increased transcription rate of alpha 2(I) gene was associated with activation of its enhancer sequence. Cells transfected with the enhancer demonstrated more than fivefold increase in CAT activity when cultured in the high-glucose medium. These studies demonstrate a multitude of effects of high ambient glucose concentrations on proximal tubule cell growth and collagen biosynthesis; cell proliferation is decreased although cell hypertrophy occurs. Procollagen gene transcription rate is stimulated and this response contributes to the observed increase in procollagen mRNA content. Activation of an enhancer sequence may be one possible mode through which high glucose levels increase the transcription of procollagen type I, presumably involving trans-acting factor(s).
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PMID:High glucose induces cell hypertrophy and stimulates collagen gene transcription in proximal tubule. 222 Nov 6

Regulatory regions of the beta-actin gene of the common carp (Cyprinus carpio) have been examined by linking upstream, 5'-flanking sequences and regions of the first intron to a bacterial chloramphenicol acetyltransferase (CAT) reporter gene. By analysis of the mRNA products and encoded CAT activity, we have identified four putative regions that influence expression: (i) a negative regulatory region 2,300 to 1,100 base pairs (bp) ahead of the gene; (ii) a proximal promoter element, containing the highly conserved CCAAT, CC(A/T)6GG, and TATA boxes, that is within the first 204 bp upstream of the initiation site; (iii) a negative element of 426 bp in the 5' region of the first intron; and (iv) a positive 304-bp element near the end of the first intron that contains highly conserved sequences found in all characterized beta-actin genes. The positive intron element is not a classical enhancer; it is position and orientation dependent, as has been observed in other housekeeping genes in vertebrates. Depending on the elements joined together, CAT gene expression can be modulated more than 500-fold in transfected mouse cells.
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PMID:Functional analysis of elements affecting expression of the beta-actin gene of carp. 235 13

The role of the cyclic-AMP (cAMP) responsive element (CRE) in eukaryotic gene transcription was investigated in several cell lines transfected by constructs containing the chloramphenicol acetyltransferase (CAT) gene linked to the three different promoters, simian virus (SV) 40, human c-Ha-ras-1, or chicken beta-actin promoter, with or without CRE. CRE had inducible enhancer activity only when it was linked to the SV40 promoter and in a few cell lines such as PC12. CRE functioned as a constitutive enhancer with the human c-Ha-ras-1 promoter in all cell lines examined. CRE also had constitutive enhancer activity when it was linked to the chicken beta-actin promoter, but this activity was observed only in KB, HeLa, and A431 cells. The different types of enhancer activities of CRE depending on the cell and promoter may be caused by interaction with different trans-acting factors that were demonstrated by gel retardation analyses.
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PMID:Dual enhancer activities of the cyclic-AMP responsive element with cell type and promoter specificity. 253 60


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