Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0023418 (leukemia)
 93,477 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The RNA polymerase activities from the nuclei of the spleen of uninfected and Rauscher murine leukemia virus-infected NIH Swiss mice were resolved by DEAE-cellulose column chromatography, and their properties were compared. The RNA polymerase activities from infected and uninfected spleens were the same with respect to column elution profiles, optimum requirements for various salts, ratios of activities with Mn2+ and Mg2+, sedimentation values, and response to most templates. With the exception of minor differences in activities with certain DNA templates, the significance of which is not clear, no qualitative differences in the enzymes from these two sources were found, but an increase in the specific activity of the alpha-amanitin sensitive enzyme, RNA polymerase II, was found in the leukemic spleen. These preliminary results suggest that there may be no novel RNA polymerase induced by Rauscher murine luekemia virus-infection, and they are in keeping with the interpretation that the viral DNA genome is transcribed by a host RNA polymerase.
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PMID:Deoxyribonucleic acid-dependent ribonucleic acid polymerases from spleen of uninfected and Rauscher murine leukemia virus-infected NIH Swiss mice.? 112 31

An aqueous extract from the marine red alga, Schizymenia pacifica has been tested in a cell free system for its effect on reverse transcriptase from avian retrovirus (avian myeloblastosis virus), and mammalian retrovirus (Rauscher murine leukemia virus). The extract inhibited reverse transcriptase from both these retroviruses but showed almost no effect, if any, on the activity of cellular DNA polymerase alpha and RNA polymerase II in vitro. Consequently it is unlikely to have an adverse effect on the growth of cultured cell. The inhibitory activity of the extract was stable over a relatively wide pH range (pH 1-11) and was not lost after pronase digestion. Inhibitory activity of the extract was lost after boiling at 100 degrees C in 0.67 N HCl, and after treatment with 100 mM NaIO4. The active principle in the extract has an apparent molecular weight in excess of 100,000 daltons. This new reverse transcriptase inhibitor is probably a polysaccharide.
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PMID:Antiretroviral activity in a marine red alga: reverse transcriptase inhibition by an aqueous extract of Schizymenia pacifica. 244 71

Protein kinase C (PKC) was purified to near homogeneity from human leukemia ML-1 cells. The purified enzyme showed a single polypeptide band of 80 kDa on SDS-polyacrylamide gel after electrophoresis, and was totally dependent on Ca2+/phospholipid for activity. Diacylglycerol and the tumor-promoting on Ca2/phospholipid for activity. Diacylglycerol and the tumor-promoting phorbol esters stimulated the enzyme activity. Autophosphorylation of PKC purified from phenyl-Sepharose column showed both 80- and 37 kDa polypeptides. Further fractionation of PKC on a hydroxyapatite column revealed two peaks of enzyme activity, indicating that there may be two different forms of protein kinase C present in human leukemia cells. The purified PKC was used to phosphorylate RNA polymerase II of human leukemia cells in vitro and the autoradiogram showed that RNA polymerase II large subunits (240, 220 and 150 kDa) were phosphorylated in a time-dependent manner.
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PMID:Isolation and purification of protein kinase C from human leukemia ML-1 cells phosphorylation of human leukemia RNA polymerase II in vitro. 275 42

The partially purified RNA polymerase II from chicken leukemia cells (Chuang R. Y., Chuang L. F. & Israel M. (1986) Biochem. Pharmacol. 35, 1293-1297) contained multiple subunits with molecular masses (in Da) ranging from 220,000 to 24,000, as shown by SDS-polyacrylamide gel electrophoresis. The enzyme was further purified through phosphocellulose column and fractions containing the enzyme activity were collected and concentrated 400-fold through a microconcentrator. The microconcentrator contained a membrane with a molecular weight cutoff around 30,000 and, hence, removed the 24,000 Da polypeptide from the enzyme. It was found that the resulting enzyme retained all the catalytic activity as compared to the enzyme preparation before the concentration step, suggesting that the stoichiometric amount of the 24,000 Da polypeptide is not required for RNA synthesis activity with a denatured DNA template.
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PMID:The 24,000 Da subunit is not required for the RNA synthesis activity of chicken leukemia RNA polymerase II. 314 27

Purified RNA polymerase II from chicken leukemia cells was found to be an effective substrate for protein kinase C but not cAMP-dependent protein kinase. Protein kinase C catalyzed the incorporation of 1-2 mol of phosphate per mol of polymerase II and the reaction was totally calcium and lipid dependent. Electrophoresis studies revealed a time-dependent increase of phosphate incorporation into RNA polymerase II subunits of 220 KDa, 180 KDa and 150 KDa, with a preferential phosphorylation of the 180 KDa polypeptide. The phosphorylated enzyme has a preference for using single-stranded DNA as the template for transcription, including transcription of the single-stranded myb oncogene sequence. Phosphoamino acid analysis indicated that both serine and threonine residues were phosphorylated at equal amounts. Phosphorylation by protein kinase C increased the affinity of substrate-polymerase binding and the initial rate of RNA synthesis, suggesting a mechanism by which gene expression can be activated by protein kinase C.
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PMID:Protein kinase C phosphorylates leukemia RNA polymerase II. 347 67

Purification of RNA polymerase II from chicken myeloblastosis (leukemia) cells to homogeneity and subsequent structural analysis of the purified enzyme revealed that the enzyme contained seven polypeptides with molecular masses ranging from 27 KDa to 220 KDa. Inclusion of protease inhibitors in the buffer system during purification significantly increased the molar ratio of the largest (220 KDa) polypeptide to the second largest (180 KDa) polypeptide. However, proteolytic conversion of the 220 KDa to 180 KDa polypeptide did not inhibit the DNA binding activity of the enzyme. The enzyme, after dissociation into subunits in a SDS-polyacrylamide gel containing urea was blotted onto a nitrocellulose filter. The filter was incubated with 32P-labeled calf thymus DNA and both the 220 KDa and 180 KDa polypeptides of the enzyme bind DNA, suggesting that the DNA-binding site of the enzyme resides on the 180 KDa polypeptide of the largest subunit.
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PMID:The 180 KDa polypeptide contains the DNA-binding domain of RNA polymerase II. 359 59

The biochemical mechanism of the N-trifluoroacetyladriamycin-14-O-hemiadipate-induced inhibition of RNA synthesis in vitro by chicken (myeloblastosis) leukemia RNA polymerase II was studied. The inhibition was found to be dependent upon preincubation of the drug with the enzyme prior to enzyme assays, suggesting that drug-enzyme interactions occur. A drug-enzyme association complex was subsequently isolated through glycerol gradient sedimentation and further characterized by fluorescent microscopic studies. The drug was dissociated from the complex upon sodium dodecyl sulfate (SDS)-gel electrophoresis, revealing the non-covalent nature of the binding between the drug and the RNA polymerase.
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PMID:Interaction of N-trifluoroacetyladriamycin-14-O-hemiadipate with chicken leukemia RNA polymerase. Formation of drug-enzyme complex. 375 49

We have investigated the ability of molecularly cloned murine type C retroviral DNA to direct accurate initiation of RNA synthesis when added to cell-free extracts. Two different cloned proviruses were used. The first was derived from an integrated molecule of AKR murine leukemia virus and contains adjacent host information. The origin of the second was an unintegrated permuted copy of Harvey murine sarcoma virus. We found that the leukemia virus cloned provirus, as predicted by structural considerations, contained two functional RNA polymerase II promoters located in the U3 region present at either end of the molecule. These promoters initiate transcription at equal rates in vitro. We also found that the permuted sarcoma virus clone contained an RNA polymerase II promoter in the U3 region. Removal of viral sequences 49 bases upstream of the in vitro sarcoma virus initiation site by restriction cleavage results in loss of specific transcription, indicating a role for this information in in vitro promotion. The 5' ends of in vitro and in vivo viral RNA were compared by nuclease mapping techniques and found to be identical. Based on this evidence, we conclude that murine retroviral genomes contain sufficient information to initiate transcription independent of any host information in vitro and that these viral promoters are probably also active in vivo. In addition to the promoter in U3, Harvey murine sarcoma virus contains a second promoter in vitro that initiates near the 5' boundary of the transformation-specific (src) region of the virus. Initiation by this promoter was insensitive to low levels of alpha-amanitin, and the RNA transcript could be terminated to yield a 340-nucleotide product.
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PMID:Specific transcriptional initiation in vitro on murine type C retrovirus promoters. 627 Jun 79

We have used a soluble in vitro RNA polymerase II transcription system to define the site of initiation of Moloney murine leukemia viral RNA synthesis. Molecularly cloned integrated and unintegrated Moloney murine leukemia virus DNAs were used as templates. The 5' ends of in vitro transcripts and virion RNA of Moloney murine leukemia virus were compared by nuclease S1 protection experiments. Our results indicate that viral sequences upstream of the in vivo cap site are implicated in the transcription of viral RNA and that the 5' end of an in vitro transcript derived from an integrated Moloney murine leukemia virus clone corresponds to the 5' end of viral genomic RNA.
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PMID:Identification of a RNA polymerase II initiation site in the long terminal repeat of Moloney murine leukemia viral DNA. 694 80

The ATP analog 5'-adenylyl imidodiphosphate (AMP-PNP) inhibits transcription of specific genes by the RNA polymerase II contained in whole cell extracts, not only with promoters that contain A as the first nucleotide of the transcript, but also with those that initiate transcripts with G or U. The analog AMP-PNP (a competitive inhibitor of ATP) probably acts at the level of initiation of transcription, but it can be used for elongation by RNA polymerase II in isolated nuclei or in the whole cell extract. AMP-PNP and the other imidotriphosphates have little effect on purified HeLa cell RNA polymerase II initiation and elongation of transcription. Since RNA polymerase III in the crude system both initiates and elongates transcripts with AMP-PNP, we conclude that the availability of the beta-gamma bond of ATP is an indispensable requirement for faithful and specific in vitro initiation only by RNA polymerase II in the whole cell extract. Uncapped U- or G-initiated transcripts were obtained in the presence of UMP-PNP or GMP-PNP, the respective imidodiphosphate analogs. The presence of the 5'-terminal imidotriphosphate at the same oligonucleotide as the cap for U-initiated precursors established that transcription initiation and capping occur at the same site. Capping is not required for transcription by RNA polymerase II in the in vitro system. Methylation of the 2' ribose of the initiating nucleotide does not occur on the imidonucleotide containing 5' ends of adenovirus EIV or murine leukemia virus long terminal repeat.
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PMID:Mechanism of RNA polymerase II--specific initiation of transcription in vitro: ATP requirement and uncapped runoff transcripts. 715 Nov 73


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