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

Patterns of histone binding to DNA of transcriptionally active D. melanogaster hsp70 genes within the nuclei have been analyzed by two methods of histone-DNA chemical cross-linking. When cross-linking is restricted to the central, "globular" regions of histones, it drops most for H1, to an intermediate extent for H2A and H2B, and least for H3 and H4 in transcriptionally active versus transcriptionally silent chromatin. When it occurs via histone terminal regions as well, cross-linking is quantitatively similar for active and inactive chromatin. Neither cross-linking method detects histones on the hsp70 promoter region. It appears that chromatin activation decreases histone binding to DNA via the "globular" regions, known to be essential for the folding of nucleosomes and the 30 nm chromatin fibril, but does not significantly affect the interaction of flexible and loosely bound histone "tails" with DNA. The role of these histone-DNA interaction changes in the unfolding of active chromatin and RNA polymerase reading through histone-bound DNA is discussed.
 ...
PMID:Change in the pattern of histone binding to DNA upon transcriptional activation. 250 14

In transient expression assays, the adenovirus E1B 19-kilodalton (19K) tumor antigen increases expression from viral promoters and the promoter for the cellular 70-kilodalton heat shock protein (hsp70). To study the mechanism of this effect, we constructed HeLa cell lines that contain stably integrated copies of the 19K gene. Compared with a 19K- control cell line, 19K+ cells produced a significantly higher level of expression from every promoter introduced into the cells by transfection. The 19K protein also increased expression of an RNA polymerase III-transcribed gene but did not affect the level of expression of the endogenous hsp70 gene. The rate of transcription from transfected promoters, as measured by a nuclear run-on assay, was higher in the 19K+ cells than in the 19K- control cells. Furthermore, the level of plasmid DNA remained higher in the 19K+ cell line, suggesting that the 19K protein stabilizes transfected plasmid DNA. The elevated DNA levels seemed to account in full for the increased transcription. The role of the 19K protein in increasing gene expression during viral infection was found to be due to a replication-dependent increase in viral DNA levels. Thus, the 19K protein activates transcription indirectly by producing a higher level of viral or plasmid DNA. The DNA stabilization function of the 19K protein is probably related to the protective role of the 19K protein during viral infection and represents the first example of a viral oncogene product that modulates gene expression by regulating viral and plasmid DNA levels.
 ...
PMID:The adenovirus E1B 19-kilodalton protein stimulates gene expression by increasing DNA levels. 253 Dec 84

We have investigated the induction of known hsp (heat shock protein) RNA and other heat shock (HS) inducible transcripts in Chinese hamster cells by various stresses including DNA damaging agents. cDNA clones coding for at least 14 different HS-inducible transcripts were isolated. By DNA sequence analysis and homology with cDNA clones of other species, some of these cDNA clones were identified as coding for hsp27, hsp89 alpha, hsp89 beta, two different hsp70s, ubiquitin, and the HS-inducible RNA polymerase III transcript B2. In addition, hsp-related cDNA clones, hsp60 and four with hsp70 homology, were isolated which coded for transcripts which were not induced by HS or other stresses in two different Chinese hamster cell lines. After HS or treatment with the HS-mimetic agent ethanol, there was coordinate induction of all 14 transcripts. With severe HS treatments which produced substantial cytotoxicity, the increase in all transcripts except B2 RNA was delayed and, in some cases, suppressed. The only DNA damaging agent, which induced many HS-inducible transcripts, was high-dose methylmethane sulfonate (MMS). However, induction by MMS was not coordinate for all transcripts as it was for HS, and B2 RNA was not induced. hsp27 RNA induction differed from the others in several respects including induction by irradiation and other agents which produce high levels of DNA damage repaired by nucleotide excision repair. The implications of these findings in cellular events such as cytotoxicity, thermotolerance, and regulation of stress responses will be discussed.
 ...
PMID:Induction of heat shock protein transcripts and B2 transcripts by various stresses in Chinese hamster cells. 254 Oct 7

The in vivo distribution of topoisomerase I on specific DNA sequences is determined at high resolution in Drosophila cells using a photo-crosslinking method. Topoisomerase I-DNA adducts are generated by irradiation of intact cells with UV light and then purified by immunoprecipitation with antibody to topoisomerase I. Analyses of the DNA sequences crosslinked to topoisomerase I by blot-hybridization with appropriate DNA probes indicate that topoisomerase I is concentrated on transcribed regions and not on nontranscribed flanking sequences. Like RNA polymerase II, topoisomerase I is recruited to heat-shock genes during the heat-shock response. However, topoisomerase I and RNA polymerase II can interact independently with the transcribed region because different ratios of topoisomerase I and RNA polymerase II are crosslinked to the highly transcribed hsp70 gene and the moderately transcribed copia genes. We hypothesize that topoisomerase I allows topological changes in DNA that are required for transcription.
 ...
PMID:Topoisomerase I interacts with transcribed regions in Drosophila cells. 300 35

We describe a method for examining the in vivo distribution of a protein on specific eucaryotic DNA sequences. In this method, proteins are cross-linked to DNA in intact cells, and the protein-DNA adducts are isolated by immunoprecipitation with antiserum against the protein. Characterization of the DNA cross-linked to the precipitated protein identifies the sequences with which the protein is associated in vivo. Here, we applied these methods to detect RNA polymerase II-DNA interactions in heat-shocked and untreated Drosophila melanogaster Schneider line 2 cells. The level of RNA polymerase II associated with several heat shock genes increased dramatically in response to heat shock, whereas the level associated with the copia genes decreased, indicating that both induction of heat shock gene expression and repression of the copia gene expression by heat shock occur at the transcriptional level. Low levels of RNA polymerase II were present on DNA outside of the transcription units, and for at least two genes, hsp83 and hsp26, RNA polymerase II initiated binding near the transcription start site. Moreover, for hsp70, the density of RNA polymerase II on sequences downstream of the polyadenylate addition site was much lower than that observed on the gene internal sequences. Examination of the amount of specific restriction fragments cross-linked to RNA polymerase II provides a means of detecting RNA polymerase II on individual members of multigene families. This analysis shows that RNA polymerase II is associated with only one of the two cytoplasmic actin genes.
 ...
PMID:In vivo interactions of RNA polymerase II with genes of Drosophila melanogaster. 301 44

By using a protein-DNA cross-linking method (D. S. Gilmour and J. T. Lis, Mol. Cell. Biol. 5:2009-2018, 1985), we examined the in vivo distribution of RNA polymerase II on the hsp70 heat shock gene in Drosophila melanogaster Schneider line 2 cells. In heat shock-induced cells, a high level of RNA polymerase II was detected on the entire gene, while in noninduced cells, the RNA polymerase II was confined to the 5' end of the hsp70 gene, predominantly between nucleotides -12 and +65 relative to the start of transcription. This association of RNA polymerase II was apparent whether the cross-linking was performed by a 10-min UV irradiation of chilled cells with mercury vapor lamps or by a 40-microsecond irradiation of cells with a high-energy xenon flash lamp. We hypothesize that RNA polymerase II has access to, and a high affinity for, the promoter region of this gene before induction, and this poised RNA polymerase II may be critical in the mechanism of transcription activation.
 ...
PMID:RNA polymerase II interacts with the promoter region of the noninduced hsp70 gene in Drosophila melanogaster cells. 309 67

Protein-DNA cross-linking of cultured Drosophila cells has shown that, in vivo, prior to the induction of heat shock, there is approximately one molecule of RNA polymerase II associated with the promoter region of the major heat shock gene, hsp70. Here, we show that this promoter-associated RNA polymerase II molecule is transcriptionally engaged and has formed a nascent RNA chain of approximately 25 nucleotides in length, but is apparently arrested at that point and unable to penetrate further into the hsp70 gene without heat induction. The detection of a post-initiation RNA polymerase complex on the promoter region of the inactive gene suggests that there is a transcriptional control mechanism that acts at a step early in transcript elongation.
 ...
PMID:The RNA polymerase II molecule at the 5' end of the uninduced hsp70 gene of D. melanogaster is transcriptionally engaged. 313 31

Xenopus cells, like many other eukaryotic cells, respond to heat treatments by increasing the rate of synthesis of a few characteristic proteins, the heat shock proteins. Because of the generality of this response, it seemed possible to examine the expression of isolated heat shock genes in a heterologous system. Phage 122 DNA, containing two identical genes coding for the Drosophila 70,000-dalton heat shock protein (hsp70 genes), was microinjected into Xenopus oocyte nuclei. The Drosophila hsp70 genes are transcribed efficiently in heat-treated oocytes (35-37 degrees C) to give RNA of the correct size and sequence content. Transcription is sensitive to low levels of alpha-amanitin and therefore is carried out by RNA polymerase II. At normal temperatures (20-28 degrees C) essentially no Drosophila-specific RNA is formed. The isolated insert fragment of phage 122 also gives RNA of correct length in heat-treated oocytes which hybridizes to the coding segment of Drosophila hsp70 genes only. At normal temperatures, however, its rate of transcription is variable and only RNA heterogeneous in size is formed.
 ...
PMID:Transcription of a Drosophila heat shock gene is heat-induced in Xenopus oocytes. 680 45

Expression of the hsp70 gene of Drosophila melanogaster is controlled at the level of transcript elongation. In the uninduced state, hsp70 possesses an RNA polymerase II complex, elongationally engaged, but paused early in the transcription unit. In this study, we have used a powerful new selection-amplification technique to analyze the RNA transcripts associated with such "paused polymerases" under non-heat shock and heat shock-induced conditions. They reveal a region of pausing on the uninduced gene in vivo spanning from +21 to +35. This region is interrupted by an area of low polymerase density, centered at about +26. Upon induction, an accumulation of short transcripts, similar in size to those associated with the paused complex, was seen. Models for polymerase pausing and release are discussed in light of these data. The increased sensitivity of our new technique also allowed us to investigate ternary complexes associated with genes with much lower levels of engaged RNA polymerase. These included two of the small heat shock genes (hsp26 and hsp27) and two metabolic genes (Gapdh-1 and Gapdh-2), where paused polymerases were thought to be present, plus two other genes (Mtn and yp1), where polymerase pausing has not been detected in the past. In both of the small heat shock genes, we found evidence of previously unknown sites of transcriptional termination, residing immediately upstream of the regions of polymerase pausing.
 ...
PMID:Short transcripts of the ternary complex provide insight into RNA polymerase II elongational pausing. 756 71

Chromatin structure can modulate gene expression by limiting transcription factor access to gene promoters. We examined sequence elements of the Drosophila hsp70 promoter for their ability to facilitate the binding of the transcription factor, heat shock factor (HSF), to chromatin. We assayed HSF binding to various transgenic heat shock promoters in situ by measuring amounts of fluorescence at transgenic loci of polytene chromosomes that were stained with an HSF antibody. We found three promoter sequences that influence the access of HSF to its binding sites: the GAGA element, sequences surrounding the transcription start site, and a region in the leader of hsp70 where RNA polymerase II arrests during early elongation. The GAGA element has been shown previously to disrupt nucleosome structure. Because the two other critical regions include sequences that are required for stable binding of TFIID in vitro, we examined the in vivo occupancy of the TATA elements in the transgenic promoters. We found that TATA occupancy correlated with HSF binding for some promoters. However, in all cases HSF accessibility correlated with the presence of paused RNA polymerase II. We propose that a complex promoter architecture is established by multiple interdependent factors, including GAGA factor, TFIID, and RNA polymerase II, and that this structure is critical for HSF binding in vivo.
 ...
PMID:HSF access to heat shock elements in vivo depends critically on promoter architecture defined by GAGA factor, TFIID, and RNA polymerase II binding sites. 759 Feb 51


<< Previous 1 2 3 4 5 6 7 8 Next >>