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)

Morphological and growth characteristics are described of a rapidly growing cell line with epithelioid and giant-cell characteristics derived from a chondrosarcoma in a male patient 65 years of age. This cell line is of considerable interest because in these cells cross-reacting antigens with known animal oncorna-viruses are present. Biochemically, the cells contain particles with a density of 1-16 with "cores" of density 1'23 associated with a reverse-transcriptase-like enzyme and with 70S RNA. Occasionally, virus-like particles were demonstrated by electron microscope in material derived from the culture medium.
Br J Cancer 1977 Apr
PMID:A new cell line from a human chondrosarcoma. 85 24

This study attempts to identify the site(s) of action of N-hydroxy-2-acetylaminofluorene (N-OH-AAF) in relation to its inhibition of rat hepatic nuclear RNA synthesis. Two hr after N-OH-AAF injection (3 mg/100 g body weight), rat hepatic nuclear synthesis and nucleolar RNA synthesis in vitro were inhibited by 60 and 80%, respectively. When total nuclear RNA polymerases were solubilized and assayed in the presence of alpha-amanitin (3.2 mug/ml), only alpha-amanitin-sensitive activity was reduced (50%) by N-OH-AAF. Diethylamino-ethyl-Sephadex column chromatography confirmed this finding and further demonstrated that RNA polymerase II was the activity selectively inhibited. Since N-OH-AAF dramatically inhibited nucleolar RNA synthesis but had little effect on RNA polymerase I activity, per se, we therefore concluded that, in addition to its direct inhibitory effect on the enzymic function of RNA polymerase II, N-OH-AAF must also cause impairment of the nucleolar DNA template function.
Cancer Res 1976 Oct
PMID:Multiple sites of action of N-hydroxy-2-acetylaminofluorene rat hepatic nuclear transcription. 95 89

In order to account for the coordinate expression of large numbers of genes that must occur during development and differentiation, a mechanism of transcription control distinct from those operating in bacteria is proposed. Transcription would be initiated by small RNA chains that would function as primers for elongation. A given species of primer RNA generated by a primary induction event would bind by complementary base pairing to a variety of sites in the genome and thus trigger the transcription of adjacent structural genes. The primer RNA region would be excised from the transcription products in the nucleus, and possibly be reutilized as primers for transcription. This model can account for the occurrence of tissue-specific nuclear RNA complementary to repetitive DNA and does not require that the major RNA polymerases be capable of initiation. A minor RNA polymerase capable of initiating primer RNA chains and subject to conventional transcription controls would be required. Carcinogenesis, which is accompanied in many cases by the appearance of a variety of embryonic antigens, could involve the induction of RNA primers normally programmed to function early in development.
Cancer Res 1976 Nov
PMID:A model for the control of transcription during development. 97 62

The nonhistone proteins of Ehrlich ascites tumor chromatin have been separated into a loosely bound and two tightly bound protein fractions by sequential extraction of chromatin with 0.35 M NaCl and 2 M NaCl:5 M urea. The nonhistone proteins thus obtained were examined for their chemical composition and distribution of DNA polymerase, RNA polymerase, and protein kinase activities. In addition, the effect of these nonhistone proteins on transcription of DNA in vitro has been determined. The results indicate that these nonhistone proteins, fractionated on the basis of their extractability, exhibit varied compositional characteristics and play different functional roles in the synthesis of DNA and RNA and in the possible control of gene activity.
Cancer Res 1976 Sep
PMID:A comparison of the loosely bound and tightly bound nonhistone proteins from Ehrlich ascites tumor chromatin. 97 79

Differences noted in enzyme II directed RNA synthesis under varying salt conditions in nuclei isolated from uninfected and Friend virus (FV)-infected spleen cells, have been attributed to chromosomal modifications (Babcock and Rich 1973). This investigation was undertaken to determine if compositional changes occur in the chromatin of FV-infected spleens, which correlate with an altered rate of synthesis by enzyme II. A quantitative study of the chromatin constituents at various times after infection indicated that they vary in the same temporal manner as the rate of RNA synthesis in isolated nuclei. Relative to DNA, RNA, histone, and nonhistone protein reached a maximum at 14 days postinfection. This was followed by a gradual decrease during the remainder of the infection. Chromatin endogenous DNA-dependent RNA polymerase activity varied in the same manner, suggesting that RNA synthesis directed by enzyme II is modulated by chromosomal proteins.
Cancer Biochem Biophys 1976
PMID:Temporal changes in chromatin isolated from Friend virus-infected mouse spleens. 101 37

Rhodium(II) acetate, propionate, and butyrate showed a considerable variation in their antitumor activity against Ehrlich ascites tumor cells in mice, with the butyrate complex being the most active. The three complexes markedly inhibited DNA synthesis of Ehrlich ascites tumor cells in vivo. Rhodium (II) butyrate was the most potent inhibitor followed by the propionate complex. One hour after administration, rhodium(II) propionate and butyrate induce more uridine-5-3H incorporation into RNA than is seen in the controls. Equilibrium dialysis studied showed that rhodium(II) acetate-1-14C binds to single stranded DNA, poly-A, ribonuclease A, and bovine serum albumin but not to highly polymerized native calf thymus DNA, poly-G, or poly-C. In these cases binding occurred at the two axial positions of rhodium(II) acetate to a nitrogen donor in the ligands. The formation constants of the rhodium(II) acetate and propionate complexes with 5'-adenosine monophosphate were determined. The rhodium(II) propionate complex was more stable. Sedimentation and viscosity measurements of poly-A and poly-A/rhodium(II) acetate complexes indicate a high degree of intramolecular crosslinking in the rhodium(II) acetate/poly-A complex. The rhodium(II) carboxylate complexes were also found to be potent inhibitors of purified DNA polymerase I and RNA polymerase from Escherichia coli.
Cancer Chemother Rep
PMID:Interaction of Rhodium(II) carboxylates with molecules of biologic importance. 110 39

Friend murine leukemia virus induces splenic enlargement and an increase in RNA polymerase activity of spleen nuclei. Actinomycin D, administered at 60 mug/kg body weight/day prevents the development os splenomegaly and the elevation of polymerase activity following infection, but it has only a slight effect on the production of virus in spleen tissue. Thus, the alteration of RNA synthesis is not a result of virus proliferation, but instead may be a manifestation of leukemic erythropoiesis. Normal erythropoiesis, stimulated by erythropoietin administration, produces a similar but transient increase in RNA polymerase activity in spleen nuclei. Erythropoietin administered before, but not after, Friend virus infection results in an enhancement of RNA polymerase activity, as measured 9 days after inoculation. This effect is most simply explained by assuming that there is a common target cell pool for both erythropoietin and Friend virus, and that this pool becomes refractory to the influence of the hormone as a result of the leukemic process.
Cancer Res 1975 Aug
PMID:Role of cellular RNA polymerases in virus-induced leukemogenesis. 114 21

Administration of N-hydroxy-2-acetylaminofluorene (N-OH-AAF) to rats inhibits liver nuclear RNA synthesis. This effect is reflected in an in vitro inhibition of RNA synthesis by isolated whole nuclei. The decreased RNA synthesis can be accounted for entirely by an inhibition of the RNA polymerase activities quantitatively solubilized and partially purified from these nuclei. Both nucleolar and nucleoplasmic polymerases are affected. A similar inhibition of the polymerases was demonstrated in intact nuclei by inactivating the endogenous template with actinomycin D and assaying the polymerases with an added exogenous template, poly(deoxyadenylate-deoxythymidylate). Chromatin was prepared from similar nuclear preparations by two methods, differing in the extent to which they remove endogenous polymerase activity. Each chromatin preparation was transcribed with added Escherichia coli or partially purified rat liver nucleoplasmic RNA polymerase respectively. With either polymerase and either chromatin preparation, no inhibition of the template activity of chromatin isolated from N-OH-AAF-treated animals could be detected. It is concluded that N-OH-AAF is a potent inhibitor of rat liver nuclear RNA synthesis and that the mechanism of this inhibition is inactivation of the RNA polymerases. At the same time, N-OH-AAF leaves the chromatin template, at least quantitatively, intact for the synthesis of RNA. The implications of such an effect of N-OH-AAF on RNA synthesis are discussed.
Cancer Res 1975 Aug
PMID:N-hydroxy-2-acetylaminofluorene inhibition of rat live RNA polymerases. 114 28

With synchronized tissue culture cells (L929), daunomycin had the greatest inhibitory effect on cell growth when the drug was administered during the later stages of cell division (late S, G2, and M). The level of binding of daunomycin to DNA was not found to be influenced by the phase of the cell cycle. The highest level of radioactivity from [eH]-daunomycin was bound to DNA of the heterochromatin fraction. Both RNA and DNA syntheses were inhibited in isolated enzyme systems when daunomycin-treated DNA, from which the unbound drug was removed by passage through Sephadex column, was used. DNA polymerase was reduced to one-fifth of the control activity, while that of RNA polymerase was reduced to one-half. Similar experiments with daunomycin-treated RNA and DNA polymerase preparations showed that the drug had no effect on the activities of the enzymes per se. Hence, the reduction of RNA and DNA polymerase activities could be accounted for by the loss of template activity of the drug-treated DNA. Daunomycin caused by a marked drop in the formation of a complex between RNA polymerase and DNA, indicating that the binding of daunomycin to DNA may give rise to steric hindrance effects that interfere with the association of the template to RNA polymerase enzyme. Sedimentation profile in alkaline sucrose density gradient of DNA that had been treated with daunomycin showed that no change in the molecular weight could be demonstrated.
Cancer Res 1975 Jun
PMID:Binding of daunomycin to DNA and the inhibition of RNA and DNA synthesis. 116 9

Bovine lymphosarcoma tissue has been extracted with low- and high-salt buffers [0.05 M Tris-C1 plus or minus 0.3 M (NH4) 2S04]. Diethylaminoethyl-Sephadex chromatography of both the high-salt and low-salt extracts yields RNA polymerases I and II, although low-salt extraction releases only one-third as much activity. Extraction by high salt of the residue from the low-salt extract, followed by diethylaminoethyl-Sephadex chromatography, yields additional enzyme activity with properties of Form II. Purification of the low-salt extract by protamine precipitation, elution with sodium succinate, and phosphocellulose chromatography yields a preparation of RNA polymerase (RNAP) with hybrid properties, combining the salt optimum of Form I, diethylaminoethyl-Sephadex elution pattern of form II, and alpha-amanitin sensitivity of Form III. RNAP. transcribes native D,A and chromatin efficiently. More RNAPL is recovered from lymphosarcoma tissue than from calf thymus.
Cancer Res 1975 Feb
PMID:RNA polymerase isolated from bovine lymphosarcoma by sequential low- and high-salt extraction. 117 19


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>