Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.7.48 (transcriptase)
 9,479 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A high-molecular-weight protein complex that is capable of accurate transcription initiation and termination of vaccinia virus early genes without additional factors was demonstrated. The complex was solubilized by disruption of purified virions, freed of DNA by passage through a DEAE-cellulose column, and isolated by glycerol gradient sedimentation. All detectable RNA polymerase activity was associated with the transcription complex, whereas the majority of enzymes released from virus cores including mRNA (nucleoside-2'-O)methyltransferase, poly(A) polymerase, topoisomerase, nucleoside triphosphate phosphohydrolase II, protein kinase, and single-strand DNase sedimented more slowly. Activities corresponding to two enzymes, mRNA guanylyltransferase (capping enzyme) and nucleoside triphosphate phosphohydrolase I (DNA-dependent ATPase), partially sedimented with the complex. Silver-stained polyacrylamide gels, immunoblots, and autoradiographs confirmed the presence of subunits of vaccinia virus RNA polymerase, mRNA guanylyltransferase, and nucleoside triphosphate phosphohydrolase I, as well as additional unidentified polypeptides, in fractions with transcriptase activity. A possible role for the DNA-dependent ATPase was suggested by studies with ATP analogs with gamma-S or nonhydrolyzable beta-gamma-phosphodiester bonds. These analogs were used by vaccinia virus RNA polymerase to nonspecifically transcribe single-stranded DNA templates but did not support accurate transcription of early genes by the complex. Transcription also was sensitive to high concentrations of novobiocin; however, this effect could be attributed to inhibition of RNA polymerase or ATPase activities rather than topoisomerase.
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PMID:Sedimentation of an RNA polymerase complex from vaccinia virus that specifically initiates and terminates transcription. 303 83

This paper presents the evolution during its follow-up of a virostatic combination study of the type I-II trial conducted on ten AIDS-related complex (ARC) or acquired immunodeficiency syndrome (AIDS) patients [1, 9, respectively]. Its concept is based on the following original notions: a) it is not the number of the virostatics applied to each patient at any phase which determines their effect; it is the number of affected virus targets which determines the effect. Thus, the so called "tritherapies", imposed by the "AIDS Command" to thousands of patients selected at random, to be compared to the same number of subjects receiving only "bi" or "monotherapies", might be beginning to face failure because they attack only two targets: retro-transcriptase and HIV1 protease. Having discovered, owing to our experimental screening, original HIV1 virostatics, acriflavine (ACF) and several ellipticine analogues among which we have used methyl-hydroxy-ellipticine (MHE), we are able to attack two virus targets unaffected by classical virostatics: ACF attacks DNA, from its integrated double branched stage to the provirus one, and MHE inhibits topoisomerase II. We experimentally combined these two agents with AZT, which inhibits retro-transcriptase, thus we realized a combination affecting three targets. This three agent combination was able to eradicate Friend's virus from infected mice. Clinically, combinations of three drugs affecting four targets (as they are selected among the ten virostatics available today) give a stronger result than three drug combinations affecting only three targets, because they were selected from the five virostatics which were the only ones available at the beginning of the present study. Five patients out of five who received the combinations of four virostatics chosen among the ten currently available (thus affecting four targets) from the beginning of their treatment to the present have all reduced their viral load (VL) and maintained it below the detectable level (< 200 RNA copies/mL then 20 copies/mL); b) as the toxicities of virostatics and as HIV1 resistances may happen as soon as 12 weeks of treatment, the combinations have been, in our study, applied in shorter (3 week) sequences, differing from each other due to drug rotation; c) neither toxicity nor resistance occurred; d) curiously, the CD4 numbers, even when they increased rapidly, has never attained their normal count, and their curve may be a Gombertzian one. This CD4 restoration limitation can be due to persisting virus, as indicated in some patients by small peaks which may appear on some VL plateaus, though they disappear without treatment change.
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PMID:Combinations of three or four HIV virostatics applied in short sequences which differ from each other by drug rotation. Preliminary results of the viral loads and CD4 numbers. 986 98

Polymerase chain reaction (PCR)-based nucleotide sequence analysis was performed in 12 cases of Ewing sarcoma on the cDNA and/or genomic DNA breakpoint regions of a t(11;22)(q24;q12), which joins the EWS gene located on chromosome 22 with the FLI1 gene located on chromosome 11, in order to understand the molecular mechanism of this translocation. Reverse transcriptase-PCR on total tumor cell RNA from the examined cases showed five types of EWS-FLI1 chimeric product, resulting from various junctions between EWS exon 7 or 10 with FLI1 exon 5, 6, or 8. Sequencing of the genomic fusion junctions of EWS-FLI1 in seven cases showing three types of the chimeric cDNA products revealed that most of the breakpoint junctions shared common nucleotide(s) from both genes, and that the breakpoints in EWS introns 7 and 10 clustered within 100 bp and 300 bp, respectively. All the junctions were found to be flanked by various oligomers, among which a consensus sequence, 5'-AGAAAARDRR-3', was found near the breakpoints of both genes in four cases, suggesting that these oligomers may have a functional significance in the genesis of t(11;22). In addition to these oligomers, sequences highly homologous to Alu repeats and/or eukaryotic topoisomerase II cleavage sites were located near, or flanked, or even encompassed, the breakpoints in most of the cases examined. Thus, these sequences may also mediate DNA double-strand breakage and rejoining to generate the t(11;22). Genomic sequence analysis of both EWS-FLI1 and FLI1-EWS chimeric genes in three of the seven cases demonstrated a deletion and duplication of both EWS and FLI1 sequences in two cases and no gain or loss in one case. The present findings suggest that multiple mechanisms may be operative for the break and rejoining of the fragments of chromosomes 11 and 22 in the genesis of t(11;22), and that some of these translocations are asymmetric at the molecular level.
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PMID:Molecular characterization of the genomic breakpoint junction in a t(11;22) translocation in Ewing sarcoma. 1022 34

We report a 50-year-old man who developed therapy-related myelodysplastic syndrome after treatment with etoposide-including chemotherapy for extratesticular germ cell tumor. Chromosomal analysis showed inversion 11 (p15q22) translocation. Reverse transcriptase-polymerase chain reaction amplification of patient RNA showed a fusion transcript of nucleoporin gene NUP98, and putative DEAD-box RNA helicase gene DDX10. NUP98 is implicated in the transformation through aberrant nucleocytoplasmic transport. DDX10 is suggested to be involved in ribosome assembly. The NUP98-DDX10 fusion transcript may promote the development of secondary hematological malignancies caused by DNA-topoisomerase II inhibitors through aberrant nucleocytoplasmic transport and/or alteration in ribosome assembly.
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PMID:Fusion of the nucleoporin gene, NUP98, and the putative RNA helicase gene, DDX10, by inversion 11 (p15q22) chromosome translocation in a patient with etoposide-related myelodysplastic syndrome. 2575 91

Treatment of acute promyelocytic leukemia (APL) with a combination of anthracycline-based chemotherapy and all-trans retinoic acid (ATRA) leads to very high rates of complete remission and survival. There are only a limited number of publications on the development of therapy-related myelodysplastic syndrome (MDS) or acute myeloid leukemia during follow-up of APL. Although drugs targeting at DNA-topoisomerase II characteristically induce translocations involving 11q23, this was seldom seen in patients treated for APL. We report on a patient initially diagnosed with APL. Response to therapy was monitored by fluorescence in situ hybridization (FISH) and reverse-transcriptase polymerase chain reaction for the PML-RARalpha rearrangement. Consecutive samples showed a swift and complete reduction of PML-RARalpha rearranged cells. Twenty months after diagnosis, however, conventional cytogenetics revealed a complex karyotype with a translocation involving 11q23 and loss of chromosomes 7q and Xq. FISH analysis with the MLL probe identified 2q37 (harboring the SEPT2 gene) as the translocation partner of chromosome 11. We consider the rather unique t(2;11)(q37;q23) as the primary event causing therapy-related MDS in our patient. This case stresses the importance of conventional karyotyping to be performed on a regular basis in all treated APL patients for the early detection of chromosomal aberrations that indicate the development of therapy-related MDS or acute myeloid leukemia.
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PMID:Translocation (2;11)(q37;q23) in therapy-related myelodysplastic syndrome after treatment for acute promyelocytic leukemia. 1820 42