Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.6 (RNA polymerase)
 34,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Adeno-associated virus (AAV) is a nonpathogenic parvovirus which normally requires helper adenovirus or herpes-virus for replication. We examined the growth of AAV type 2 in human lymphocytes and its possible interaction with HIV-1. Three B cell lines (CK-B, HS-2, and UC729) and four T cell lines (Molt-4, Jurkat, HUT78, and HUT78+HIV, which is persistently infected with HIV-1) were infected with AAV either in the presence or in the absence of adenovirus. AAV DNA was found in cells of all the lines following incubation with the virus, indicating absorption. AAV DNA replication occurred in most cell lines without particular preference for B or T cells, but only in the presence of helper virus, either adenovirus or Epstein-Barr virus. Expression of AAV proteins was examined by immunoblotting and ELISA, using sera specific for AAV Rep or capsid proteins. The level of AAV protein synthesis correlated with the efficiency of AAV DNA replication, and both varied between cell lines. The yield of infectious AAV was low in most cases, except in one T4 line (Jurkat), where AAV replication and protein synthesis in the presence of adenovirus were very extensive. In HUT78+HIV cells both adenovirus and AAV (in the presence of Ad2) replicated efficiently. The effects of adenovirus plus AAV coinfections on HIV-1 replication, measured by reverse-transcriptase (RT) activity, were mild. Infection with adenovirus or AAV alone resulted in a 60-70% increase in RT activity, while infection with AAV plus adenovirus resulted in a 20% decrease in RT activity. The yield of infectious AAV in this cell line was very low.
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PMID:Replication of adeno-associated virus type 2 in human lymphocytic cells and interaction with HIV-1. 137 38

Steroid receptors have been reported to stimulate transcription in a manner synergistic with other transcription factors. We have examined this synergism or functional cooperativity between glucocorticoid receptors and basal transcription factors in a variety of promoter and reporter gene contexts. A fragment containing a hormone response element from mouse mammary tumor virus was fused to well characterized promoters from the herpes virus thymidine kinase and mouse beta-globin genes and to related mutant promoters altered by inactivation of transcription factor-binding sites through point mutagenesis or deletion. These constructs were transfected into glucocorticoid-sensitive fibroblasts, and reporter gene activity was assessed with or without hormonal stimulation. In contrast to previous studies, we found little indication of synergistic interaction between elements mediating a hormone response and adjacent basal promoters. In fact, we observed that inactivating basal factor-binding sites, thereby decreasing promoter strength, actually increased hormone inducibility. We suggest that the inverse relationship between basal promoter strength and the induction ratio attained upon hormonal stimulation may be due to limitation of a common factor, an "adaptor" through which glucocorticoid receptor and basal transcription factors interact with the components of the RNA polymerase II complex to stimulate rates of transcription.
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PMID:Concerted stimulation of transcription by glucocorticoid receptors and basal transcription factors: limited transcriptional synergism suggests mediation by coactivators/adaptors. 207 21

One gene activator protein may interfere with the effects of another in eukaryotic cells. We report here that a hybrid yeast-herpes gene activator protein inhibits transcriptional activation by a thymidine-rich DNA element in yeast. This example of activator interference can be faithfully reproduced in vitro. Interference is reversed by a partially purified yeast component, but not by RNA polymerase II or various polymerase II transcription factors. We conclude that the partially purified yeast component is a novel factor, and we suggest this factor mediates the transcriptional activation process.
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PMID:A novel mediator between activator proteins and the RNA polymerase II transcription apparatus. 216 59

We have used partially purified preparations of RNA polymerase II from mock-infected and herpes simplex virus type 1-infected HEp-2 cells to transcribe the herpes simplex virus type 1 strain F BamHI Z DNA fragment containing the promoter for immediate-early RNA-5 (alpha 47), a 1.8-kilobase, spliced RNA. In agreement with the in vivo transcriptional regulation of herpes simplex virus type 1 immediate-early genes, electrophoretic analyses of runoff and truncated transcripts from this template showed that RNA polymerase II from mock-infected cells initiates transcription more selectively than does that from the herpes virus-infected cells at the immediate-early RNA-5 promoter. S1 nuclease mapping of the 5' ends of in vivo- and in vitro-synthesized mRNA placed the initiation site ca. 110 base pairs upstream from the previously published site and also demonstrated the presence of a second, smaller intervening sequence between this new cap site and the previously characterized intervening sequence. S1 analyses also suggested that some splicing of the larger but not the smaller intervening sequence occurred in vitro.
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PMID:In vitro transcription of herpes simplex virus genes: identification of a new initiation site and second intervening sequence in the immediate-early RNA-5 gene. 298 42

The effect of DNA methylation on the transcriptional activity of the hamster adenine phosphoribosyltransferase (aprt) and the herpes thymidine kinase (tk) genes has been investigated. By using M13 constructs containing these gene sequences, specific segments of each gene were methylated in vitro by restriction fragment primer-directed second-strand synthesis using the substrate 2'-deoxy-5-methyl-cytidine triphosphate (dmCTP). These hybrid-methylated molecules were inserted into mouse Ltk- cells by DNA-mediated cotransfer. In all cases, the integrated sequences retained the in vitro-directed methylation pattern. The aprt gene was inhibited by CpG methylation in the 5' region but was unaffected by methylation at the 3' end or in adjacent M13 sequences. In contrast to this, DNA methylation in both the 5' promoter region and the 3' structural region of the tk gene had a strong inhibitory effect. This suggests that this modification may affect transcription by mechanisms that do not involve the direct alteration of recognition sequences for RNA polymerase.
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PMID:Effect of regional DNA methylation on gene expression. 385 99

The transcriptional programme of the herpes viruses is organised into three principal phases. The immediate-early (IE) genes are the first to be transcribed, by the pre-existing host RNA polymerase II, and their promoters are strongly stimulated by a polypeptide component of the virus particle. The E and L gene promoters become active only after the appearance of IE gene products. Genetic and biochemical evidence has shown that the HSV-1 IE polypeptide Vmw175 (ICP 4) is essential for the trans activation of HSV early promoters, but the role of none of the other four IE gene products was known. This paper describes functional tests that show, by co-transfection of recombinant plasmids into HeLa cells, that (i) Vmw175 alone can activate an HSV-1 E gene promoter, (ii) the four other HSV-1 IE gene products by themselves are unable to activate transcription, (iii) the combination of Vmw175 plus the product of IE gene 1, Vmw110 (ICP 0), is a much better activator than Vmw175 alone, (iv) cloned IE gene products of human cytomegalovirus (CMV), varicella-zoseter virus (VZV) and pseudorabies virus (PRV) can also activate transcription from an HSV-1 early promoter, and (v) this activation also occurs with cellular promoters.
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PMID:Trans activation of transcription by herpes virus products: requirement for two HSV-1 immediate-early polypeptides for maximum activity. 609 66

In this review we try to examine some of the recent developments in our understanding of the mechanisms that control gene expression in eukaryotes. We discuss the nature of the positive regulation exerted by adenovirus, herpes virus or papova immediate early proteins. These proteins which can activate homologous promoters can also stimulate transcription from cellular promoters present on transfected DNA. This property of the E1a gene product of Adenovirus e.g. may be related to its immortalizing function. Transcription of cellular genes can be stimulated by viral or cellular short DNA elements named enhancers. These elements acting in cis, can be placed 5' or 3' to the gene and function in both orientations. Some of them show a remarkable cell specificity in their action. Enhancers affect the chromatin structure by creating a local nuclease sensitive region that may serve as an entry site for RNA polymerase II or for factors involved in the process of transcription initiation.
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PMID:Regulation of eukaryotic gene expression by transactivating proteins and cis acting DNA elements. 623 75

Using both clones of mouse LMTK- cells cotransformed with various chimeric conalbumin promoter simian virus 40 (SV40) early gene recombinants and the herpes thymidine kinase gene, and HeLa cells transfected with the same chimeric recombinants, we show that the SV40 72 base pair (bp) repeat sequence is a bidirectional potentiator of initiation of transcription from adjacent T-A-T-A box-dependent and -independent start sites. These results are consistent with our previous model based mainly on the results of T antigen gene expression assays that the 72-bp repeat acts as a bidirectional entry site for RNA polymerase B. We also show that the conalbumin T-A-T-A box is an important element for efficient and accurate in vivo initiation of transcription.
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PMID:A novel eukaryotic promoter element: the simian virus 40 72 base pair repeat. 631 2

The gene encoding the primase small subunit was isolated from genomic DNA of strain K1 of the human malarial parasite Plasmodium falciparum. Isolation of a complete cDNA clone revealed the presence of 15 introns in the genomic sequence. This is unprecedented for Plasmodium genes, which usually contain no or only 1 or 2 introns. The gene is present as a single copy and the cDNA contains an open reading frame of 1356 nt encoding a protein of 452 amino acids. A single mRNA of 2.1 kb was identified by Northern blotting. Comparison of the amino acid sequence with five eukaryotic small primase subunits revealed the presence of eight conserved regions. Sequence alignments allowed the identification of putative motifs A, B and C that are essential features of the catalytic centre of DNA polymerases, RNA polymerases and reverse transcriptases. Also, similarity of a C-terminal region of approximately 100 amino acids to a conserved region in herpes virus primases, alpha-like DNA polymerases and RNA polymerase II was noted. The complete gene was expressed as a fusion product containing an N-terminal polyhistidine tag using a baculovirus expression vector. The protein was overproduced in insect cells and purified. Activity assays demonstrated the ability of the p53 subunit to initiate de novo primer formation.
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PMID:Molecular cloning of a Plasmodium falciparum gene interrupted by 15 introns encoding a functional primase 53 kDa subunit as demonstrated by expression in a baculovirus system. 891 94

Primary effusion lymphoma (PEL) is a distinct clinicopathologic entity associated with Kaposi's sarcoma-associated herpes virus (KSHV). Several cytokines, including interleukin-6 (IL-6), basic fibroblast growth factor (bFGF), and platelet-derived growth factor (PDGF) may be important for survival of KS cells. However, little is known about the interaction of cytokines with KSHV-infected lymphocytes from PEL. Therefore, we investigated what cytokines were produced by KSHV-infected PEL cell lines (KS-1, BC-1, BC-2), what cytokine receptors were expressed by these cells, what response these cells had to selected cytokines, and what was the effect of IL-6 antisense phosphorothioated oligonucleotides. Reverse transcriptase-polymerase chain reaction (RT-PCR) and protein studies showed that these three cell lines produced IL-10, IL-6, and the receptors for IL-6. The granulocyte macrophage colony-stimulating factor (GM-CSF), IL-1beta, IL-8, IL-12, bFGF, PDGF, and c-kit transcripts were not detected in the cell lines. High levels (0.7 to 5 ng/mL/10(6) cells/48 hours) of IL-6 protein were consistently detected in supernatants of the cell lines by enzyme-linked immunosorbent assay (ELISA) tests. In clonogenic assays, interferon-alpha (IFN-alpha) and IFN-gamma suppressed the clonal growth of the PEL cells, but GM-CSF, IL-4, IL-6, IL-8, IL-10, and oncostatin M did not change it. We examined for several autocrine loops that have been suggested to occur in KS. Experiments using antisense oligonucleotides showed that the clonal growth of KS-1 and BC-1 was nearly 100% inhibited by IL-6 antisense oligonucleotides (10 micromol/L), but not at all by either oligonucleotides (</=10 micromol/L) to IL-6 sense, IL-6 scrambled, viral IL-6 (vIL-6) antisense, or IL-10 antisense. Furthermore, the IL-6 antisense oligonucleotides had no effect on two B-cell lymphoma cell lines, which were not infected with KSHV. Addition of IL-6 antibody did not inhibit clonal growth of any of the cell lines. Taken together, we have defined the cytokines and their receptors expressed on PEL cells and have found that these cells synthesized IL-6 and IL-6 receptors; interruption of this pathway by IL-6 antisense oligonucleotides specifically prevented the growth of these cells. These findings will offer potential new therapeutic strategies for PEL.
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PMID:Mechanisms of growth control of Kaposi's sarcoma-associated herpes virus-associated primary effusion lymphoma cells. 951 48


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