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)

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

The induction of human immunodeficiency virus type 1 (HIV-1) gene expression by cytokines was investigated in cells of central nervous system origin. These were human neuroblastoma, glioblastoma, and astrocytoma cell lines, a murine oligodendroglioma and primary murine astrocyte cultures. The cytokines used were tumor necrosis factor alpha (TNF alpha), interleukin-1 beta (IL-1 beta), IL-6, and interferons alpha and gamma (IFN alpha, gamma). Transient transfection of cells with a chloramphenicol acetyltransferase (CAT) reporter gene under the control of the HIV-1 long terminal repeat (LTR) showed significant augmentation following treatment by particular cytokines. TNF alpha was found to augment HIV LTR-directed CAT activity in all cell types. IL-1 beta also activated the HIV LTR reporter gene in glioblastoma, astrocytoma, and astrocyte cells. IL-6 enhanced HIV gene expression in one example only, the primary astrocyte cultures. The interferons generally suppressed expression from the LTR except IFN gamma which produced a twofold rise in the murine glial cells and IFN alpha augmenting expression in one neuroblastoma cell line. No synergy was observed between pairs of activating cytokines tested. The HIV tat gene product was found to be functional in all cells, cotransfection of a tat expression vector transactivating expression from the LTR, with varying degrees of efficiency. In some cell lines the combination of an activating cytokine and tat resulted in an enhancement above that obtained by cotransfection of tat alone. In others, the level of CAT activity did not significantly change. Analysis of nuclear extracts from cytokine-treated cells further implicated the involvement of NFKB in the induction of HIV-1 gene expression.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Cytokine augmentation of HIV-1 LTR-driven gene expression in neural cells. 159 55

We have been studying the role of human cytomegalovirus (HCMV) as a potential cofactor in human immunodeficiency virus (HIV)-related disease. The clinical relevance of HCMV is highlighted by the fact that it is a principal viral pathogen in patients with AIDS and is known to infect the same cells as HIV. In this study, we focused on the molecular interactions between HIV and HCMV in human fibroblasts and in the human glioblastoma/astrocytoma-derived cell line U373 MG, cells which can be productively infected by both viruses. Because these cells are CD4-, we used HIV pseudotyped with a murine amphotropic retrovirus as described previously (D. H. Spector, E. Wade, D. A. Wright, V. Koval, C. Clark, D. Jaquish, and S. A. Spector, J. Virol. 64:2298-2308, 1990). Initial studies showed that when cells were preinfected with HIV (Ampho-1B) for 5 days and then superinfected with HCMV, HIV antigen production dropped significantly in the coinfected cells but continued to rise in cells infected with HIV (Ampho-1B) alone. HCMV production, however, was unaffected by the presence of HIV. Further analysis showed that HIV steady-state RNA levels and gag and env protein production were also inhibited in the presence of HCMV. The transcriptional inhibition of HIV was particularly surprising in view of the previous results of several other laboratories as well as our own that HCMV infection stimulates HIV long terminal repeat-chloramphenicol acetyltransferase (LTR-CAT) expression in transient expression assays. To investigate this further, we transfected the HIV LTR-CAT construct into either uninfected cells or cells which had been preinfected with HIV. The cells were infected with HCMV 24 h posttransfection and assayed for CAT gene expression at 48 h after HCMV infection. Although there was some stimulation of the LTR-CAT in cells that were dually infected by HIV and HCMV, it was 16-fold less than that in the cells infected only with HCMV. This suggests that in the presence of the HIV infection, the stimulation of the HIV LTR-CAT gene by HCMV is significantly reduced. Experiments with UV-irradiated HCMV and the HCMV DNA polymerase inhibitor ganciclovir showed that HCMV transcription is necessary for the reduction in HIV production to occur; however, replication of the HCMV genome or any events which take place after DNA replication are not necessary. These results, coupled with the observation that inhibition is usually first seen between 8 and 24 h after HCMV infection, suggest that an HCMV early protein is involved in repression of HIV.
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PMID:Human cytomegalovirus inhibits human immunodeficiency virus replication in cells productively infected by both viruses. 165 86

Interferon-gamma (IFN-gamma) regulates a variety of immunoregulatory functions through the induction of a specific set of IFN-gamma response genes. This includes the invariant chain associated with the major histocompatibility complex class II molecules. To investigate the mechanism involved in the invariant chain (In) response to IFN-gamma we constructed chloramphenicol acetyltransferase (CAT) hybrid genes in which the CAT gene is under the control of the In promoter. The glioblastoma cell line, U-373 MG, transfected with a CAT construct having the In promoter sequence -790 to +1 bp showed over 3-fold increased CAT activity when treated with IFN-gamma indicating that this region confers IFN-gamma responsiveness to the CAT gene. The IFN-gamma response element in the promoter was further sublocalized to the region -120 to -61 base pairs (bp). This region contains homology to the interferon-stimulated response elements identified in other IFN responsive genes. By gel shift analyses, an IFN-gamma-induced sequence-specific DNA-binding factor was identified. This induced complex binds to an oligonucleotide corresponding to -107 to -79 bp of the In promoter. Mutations of this binding site at -94 and -92 bp drastically decreased binding of the constitutive and IFN-gamma-induced complexes. This IFN-gamma induced factor also binds to an oligonucleotide corresponding to -91 to -62 bp of the interferon-beta (IFN-beta) gene promoter, a region necessary for the induction of the IFN-beta gene by virus and double-stranded RNA. This binding specificity is characteristic of a family of DNA binding factors that bind both the interferon-stimulated response elements and the IFN-beta gene promoter.
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PMID:Interferon-gamma-inducible regulation of the human invariant chain gene. 189 64

Invariant chain (Ii) is intracellularly associated with MHC class II molecules, is implicated in class II function, and is coordinately regulated with the alpha- and beta-chains of MHC class II genes at the transcriptional level. Included among the various cis-acting elements of transcriptional control in MHC class II genes are the class II boxes, X and Y, and sequences 5' of X in the W (Z, H, S) region of class II genes. The Ii promoter region contains homologues of these elements, designated here as X, Y', and "W". This study utilized transient transfection and chloramphenicol acetyltransferase analysis to investigate the role of these elements in basal and inducible Ii gene expression. Invariant chain X, Y', and "W" all contribute to gene expression in B lymphoblastoid cell lines, making them likely candidates to mediate coordinate control of class II and Ii genes. IFN-gamma-inducible expression of the Ii gene in a glioblastoma cell line is also regulated through X, Y', and "W". Thus, the Ii class II boxes and "W" have dual roles in basal and inducible gene transcription.
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PMID:Sequences homologous to class II MHC W, X, and Y elements mediate constitutive and IFN-gamma-induced expression of human class II-associated invariant chain gene. 190 95

We examined the signal transduction mechanism responsible for the IFN-gamma-induced HLA class II molecule expressions on glioblastoma cell lines, T98G and A172. A series of experiments demonstrated that the activation of protein kinase C (PKC) is involved in the DR and DP molecule expressions on T98G cells. In addition to the activation of PKC, calcium influx appeared to be involved in the DR and DP molecule expressions on T98G. Northern blot analyses with actinomycin D or cycloheximide revealed that these second messengers induce the transcription of DRA and B and DPA and B genes without de novo protein synthesis. Furthermore, we examined the region of the DPB gene that is responsible for IFN-gamma-induced gene transcription by gene transfer of a series of 5' and 3' deletion mutants in which the upstream region of the DPB was linked to a reporter gene, chloramphenicol acetyltransferase. By using these deletion mutants, it appeared that the region between -152 and -126 bp contains a critical IFN-gamma-responsive element. Taken together, these results suggest that IFN-gamma activates PKC and stimulates calcium influx, resulting in the induction of transcription of DRA and B and DPA and B genes without de novo protein synthesis. In DPB gene, we speculate that preexiting protein(s) phosphorylated by PKC in the presence of Ca2+ might directly bind or indirectly interact with the region between -152 and -126 bp of the upstream sequence, leading to the induction of the transcription (possibly in concert with other nuclear protein(s) bound to the promoter sequences).
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PMID:Regulation of HLA class II molecule expressions by IFN-gamma. The signal transduction mechanism in glioblastoma cell lines. 221 76

alpha B-Crystallin, first identified as a structural component of the vertebrate eye lens, is expressed at high levels in lens and at lower levels in a number of other tissues, most notably cardiac and skeletal muscle, kidney, and brain. We have cloned and sequenced the human alpha B-crystallin gene and show that it is structurally similar to its hamster homolog. We have also identified its transcription initiation site in human lens RNA. Functional analysis of a promoter fragment extending from -537 to +21 (relative to the transcription initiation site) and fused to the bacterial chloramphenicol acetyltransferase gene suggests that this fragment contains regulatory elements that function preferentially, but not exclusively, in lens. In contrast, this fragment is apparently insufficient to promote transcription in glial cells, as this construct functioned poorly in a glioblastoma-astrocytoma cell line (U-373MG) that synthesizes high levels of the endogenous alpha B-crystallin gene product.
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PMID:Human alpha B-crystallin gene and preferential promoter function in lens. 238 86

In this report, we determined that induction of the DR alpha-chain by recombinant human interferon-gamma (IFN-gamma) in a human glioblastoma multiform cell line is transcriptionally regulated and showed that protein synthesis is not necessary for this to occur. The regions of the DR alpha-chain gene that are responsible for basal and recombinant IFN-gamma-induced gene transcription have been determined by gene transfer of a series of 5' deletion mutants in which the upstream region of the DR alpha chain was linked to a reporter gene, chloramphenicol acetyltransferase. Chloramphenicol acetyltransferase transcript and protein levels were determined by S1 nuclease protection and chloramphenicol acetyltransferase enzyme assays, respectively. By using these deletion mutants, we were able to draw the following conclusions. (i) One hundred and nine base pairs of upstream sequence contains the basic DR alpha-chain gene promoter and represents the minimal amount of sequence necessary for basal gene expression. (ii) An additional 9 base pairs of upstream sequence can mediate recombinant IFN-gamma induction. (iii) Maximal recombinant IFN-gamma induction requires at most an additional 23 base pairs of upstream sequence. (iv) The sequence between positions -267 and -141 does not appear to contain any additional positive or negative regulatory elements. These results suggest that the region between positions -141 and -109 contains a critical IFN-gamma-responsive element. Substitution mutagenesis was performed to confirm this suggestion.
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PMID:Detailed delineation of an interferon-gamma-responsive element important in human HLA-DRA gene expression in a glioblastoma multiform line. 284 68

The c-kit proto-oncogene encodes a tyrosine kinase receptor for stem cell factor and plays a critical role in the growth and differentiation of various types of cells including hematopoietic stem cells. To investigate the mechanisms of its transcriptional regulation, we isolated the 5' flanking region of the human c-kit gene and characterized its promoter activity in hematopoietic cells. Nucleotide sequence analysis revealed that the 1.2 kb 5' flanking region lacked a typical "TATA box," but had a relatively high G + C content and four potential Sp1-binding sites. Putative binding sites for AP-2, basic helix-loop-helix proteins, Ets-domain proteins, Myb and GATA-1 were also found. Primer extension and S1 nuclease protection analyses of hematopoietic cells indicated that the major transcription start sites are 62 bp and 58 bp upstream of the translation start site. Essentially the same start sites were detected in non-hematopoietic cells such as small cell lung carcinoma and glioblastoma: this single promoter in c-kit is different from the multiple promoter system of c-fms, a c-kit-related gene, in which at least two promoters are differently used in hematopoietic and non-hematopoietic cells. An analysis of the c-kit 5' flanking region using the bacterial chloramphenicol acetyltransferase gene (CAT assay) in human erythroleukemia HEL cells, which express the endogenous c-kit mRNA at high levels, showed that a region from -180 to -22 is important for the expression of the c-kit gene. In addition, a negative regulatory element(s) is suggested to be involved in the regulation of the c-kit gene expression in mammals.
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PMID:Characterization of the promoter region of the human c-kit proto-oncogene. 750 48

We have previously isolated two different aFGF cDNA clones from kidney and brain. The two corresponding mRNA, designated aFGF 1.A and 1.B, are the predominant species in kidney and brain, respectively. During the characterization of aFGF mRNA in glioblastoma cells, we demonstrated that aFGF mRNA in U1242MG and D65MG glioblastoma cells contain 5'-untranslated sequences different from those of 1.A and 1.B. Through a strategy combining chromosome walking, identification and sequencing of evolutionarily conserved DNA regions, and a reverse transcription and polymerase chain reaction (RT-PCR)-based assay for RNA expression, we have isolated two novel aFGF cDNA clones. The cDNA clone representing aFGF mRNA 1.C was isolated from U1242MG cells; another aFGF cDNA, designated 1.D, was isolated from D65MG cells. Promoter 1C has extensive sequence homology to the hamster aFGF gene promoter that was shown to respond to testosterone stimulation by chloramphenicol acetyltransferase reporter gene assays. Using RT-PCR, we showed that normal, benign and cancerous prostate tissues do not express aFGF 1.C mRNA. In contrast, a prostate carcinoma cell line (PC-3) expresses 1.C mRNA. RT-PCR using 1.D-specific primers showed that kidney, brain and prostate do not express 1.D mRNA even though kidney and brain are the most abundant source for aFGF protein. RNase protection analysis further showed that 1.D mRNA is the predominant aFGF transcript in D65MG glioblastoma cells and in NFF-6 neonatal foreskin fibroblast cells. The genomic DNA corresponding to these two cDNA clones and the 5'-flanking regions were also isolated and their sequences determined. These DNA clones will provide important reagents for studying the regulatory elements of aFGF gene expression.
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PMID:Cloning of two novel forms of human acidic fibroblast growth factor (aFGF) mRNA. 768 Jan 20


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