Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.7.7.49 (reverse transcriptase)
31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effects of human alpha-, beta-, or gamma-interferon (IFN) on the replication and production of human T-lymphotrophic virus type-I (HTLV-I) were investigated in a human T-cell line, MT-2. Virus transmission and production estimated by syncytium formation and HTLV-I-associated reverse transcriptase (RT) activity were strongly suppressed in the presence of alpha- and beta-IFN, but not gamma-IFN. However, the expression of virus specific proteins gp46 but not p19, p24, p28, p36, and gp68 was affected with IFNs as revealed by Western blotting analysis. Electron microscopic observations showed that some of the HTLV-I particles were trapped in the intracellular vacuoles in the presence of high doses of alpha- or beta-IFN. Continuous supply of IFNs appeared to be essential for the constant suppression of RT activity. These results suggest that alpha- and beta-IFN do not inhibit HTLV-I gene expression strikingly but suppress processing or assembly of virus proteins and/or releasing of virions in the late phase of maturation.
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PMID:Suppressive effects of interferons on the production and release of human T-lymphotropic virus type-I (HTLV-I). 170 Oct 80

The gag-pol precursor protein of the avian sarcoma-leukosis virus is processed into three known pol-encoded mature polypeptides; the 95- and 63-kilodalton (kDa) beta and alpha subunits, respectively, of reverse transcriptase and the 32-kDa pp32 protein. The pp32 protein possesses DNA endonuclease activity and is produced from the precursor by two proteolytic cleavage events, one of which removes 4.1 kDa of protein from the C terminus. A 36-kDa protein (p36pol) which retains this C-terminal segment is detectable in small quantities in virions. We have constructed Escherichia coli plasmid clones that express the C-terminal domains of pol corresponding to pp32 and p36. These proteins have been purified by column chromatographic methods to near homogeneity. No significant differences could be detected in the enzymatic properties of the bacterially produced p32pol and p36pol proteins. Both possess DNA endonuclease activity and, like the pp32 protein isolated from virions, can cleave near the junction of two tandem avian sarcoma-leukosis virus long terminal repeats in double-stranded supercoiled DNA substrates. In the presence of Mg2+, both p32pol and viral pp32 cleave either strand of DNA 2 nucleotides 5' to the junction.
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PMID:Properties of avian sarcoma-leukosis virus pp32-related pol-endonucleases produced in Escherichia coli. 283 18

A retrovirus designated RPMI 8226V, isolated in 1973 from the human myeloma cell line RPMI 8226 has been characterized by competition radioimmunoassay (RIA) for the major viral structural protein and by nucleic acid hybridization analysis using cDNA of the virus. The virus is highly related to the squirrel monkey type D retrovirus, SMRV. In the homologous RIA using rabbit anti-RPMI 8226V and 125I-labelled p37 of RPMI 8226V, RPMI 8226V and SMRV exhibited competition of 81% and 73% respectively. Similarly, in the homologous system for SMRV p36, these viruses competed 98 and 100%. Reagents made from the type D retrovirus. Mason Pfizer Monkey Virus (MPMV), known to be related but distinct from SMRV, were used in assays designed to detect interspecies determinants of type D retroviruses. In assays using goat anti-MPMVp26 vs SMRV 125I-p36, RPMI 8226V, SMRV and MPMV competed to the same extent (93%). Hybridization analysis of RPMI 8226V cDNA showed significant homology to cellular RNA and DNA of mink, bat, and human cell infected with RPMI 8226V and to DNA or SMRV infected cells but not to uninfected cells or cells infected with other viruses. These results taken together clearly indicate that RPMI 8226V and SMRV are very closely related to each other. The finding of a type D retrovirus in this human myeloma cell line that had been used in EBV studies (the usual source of EBV being the marmoset cell line B95-8) prompted a survey of RPMI 8226V in some human and marmoset cell lines. The assays included the RIA for p36, nucleic acid hybridization using cDNA of RPMI 8226V, reverse transcriptase analysis and electron microscopy (EM). The results clearly show that in addition to RPMI 8226, human Burkitt lymphoma cells BJAB/B-95-8/K which were supertransformed by EBV from B-95-8/K marmoset cells as well as marmoset cell lines [(B-95-8/K and B-95-8/N) obtained from Stockholm and Uppsala, Sweden] were positive for the RPMI 8226V. Similar lines obtained elsewhere were negative. The results obtained clearly indicate that RPMI 8226V is a serious laboratory contamination in some widely used human cell lines. The possible impact of this viral contamination for some virological and cell biological studies is discussed.
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PMID:Identification of the RPMI 8226 retrovirus and its dissemination as a significant contaminant of some widely used human and marmoset cell lines. 628 81

In the pediatric cancer alveolar rhabdomyosarcoma, characteristic t(2;13)(q35;q14) or variant t(1;13)(p36;q14) chromosomal translocations generate PAX3-FKHR or PAX7-FKHR fusion genes. Using fluorescence in situ hybridization, reverse transcriptase-polymerase chain reaction and quantitative Southern blot analyses, we demonstrate that these fusion genes are amplified in 20% of fusion-positive tumors. In particular, we found in vivo amplification of these fusions in one of 22 PAX3-FKHR-positive cases and five of seven PAX7-FKHR-positive cases. These findings indicate that translocation and amplification can occur sequentially in a cancer to alter both the structure and copy number of a gene and thereby activate oncogenic activity by complementary mechanisms.
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PMID:In vivo amplification of the PAX3-FKHR and PAX7-FKHR fusion genes in alveolar rhabdomyosarcoma. 878 35

Alveolar rhabdomyosarcoma (ARMS) is associated with the specific chromosomal translocation (2;13)(q35;q14) or its rarer variant t(1;13)(p36;q14), which produces the fusion gene PAX7-FKHR. Here we describe the human cell line RC2, derived from an ARMS, which harbors a cryptic t(1;13)(p36;q14) and concomitantly shows amplification of the PAX7-FKHR fusion gene and of the MYCN oncogene. The t(1;13) and MYCN oncogene were studied by standard cytogenetic analysis and molecular techniques. The reverse transcriptase polymerase chain reaction demonstrated the expression of PAX7-FKHR mRNA in RC2 cells, although karyotype analysis failed to demonstrate a t(1;13)(p36;q14) chromosomal translocation or a derivative 13 chromosome. Double minute chromosomes were detected in all the metaphases studied. Fluorescence in situ hybridization analysis revealed multiple copies of the PAX7-FKHR fusion gene localized exclusively on a subset of double minutes, whereas multiple copies of MYCN were identified on other double minute chromosomes. Southern-blot analysis demonstrated that RC2 cells contain approximately 20 copies of the MYCN oncogene. So far no continuous RMS cell line carrying the t(1;13)(p36;q14) has been described, and PAX7-FKHR and MYCN amplifications have always been reported to occur separately in rhabdomyosarcoma (RMS). The availability of an ARMS cell line that harbors the t(1;13)(p36;q14) constitutes a useful tool for further understanding the role of the PAX7-FKHR fusion gene in RMS oncogenesis and may improve knowledge of the possible relation between PAX7-FKHR and MYCN amplification.
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PMID:Concomitant amplification and expression of PAX7-FKHR and MYCN in a human rhabdomyosarcoma cell line carrying a cryptic t(1;13)(p36;q14). 1106 97

Gene alterations accumulate during the progression of acute myelogenous leukemia (AML) to a malignant clone. Here, a new myeloid cell line, designated YSK-21, with the balanced t(8;21)(q22;q22) and the unbalanced der(1)t(1;17)(p36;q21), was established. YSK-21 grows well in a medium containing recombinant human granulocyte colony-stimulating factor (rhG-CSF), granulocyte-macrophage colony-stimulating factor (rhGM-CSF), or interleukin-3 (rhIL-3). Molecular analysis using the reverse transcriptase-polymerase chain reaction (RT-PCR) and fluorescence in situ hybridization (FISH) revealed that t(8;21)(q22;q22) resulted in an AML1-MTG8 fusion transcript. FISH and spectral karyotyping (SKY) in conjunction with G-banding analysis revealed a der(1)t(1;17)(p36;q21) chromosomal translocation, which appeared in the clone developed from the original leukemic cells. Molecular analysis of the TP73 gene on 1p36 and the TP53 gene revealed a deletion of one-allele in TP73 with partial demethylation of another allele in the initial clone of YSK, and a point mutation consisting of an A-->T substitution in codon 288 of the TP53 gene in the developed clone of YSK-21. YSK-21 cells, expressing aberrant AML1-MTG8, TP53, and TP73 protein molecules, may be useful for elucidating the pathophysiology of these aberrant proteins and for studying the der(1)t(1;17)(p36;q21) chromosomal translocation.
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PMID:Establishment of a cell line with AML1-MTG8, TP53, and TP73 abnormalities from acute myelogenous leukemia. 1155 Feb 87

Rhabdomyosarcoma (RMS) is the most common soft-tissue sarcoma in childhood. Histologically, it is subdivided histologically into two main subtypes: alveolar (ARMS) and embryonal (ERMS). ARMS is characterized by t(2;13)(q35;q14) or its variant t(1;13)(p36;q14), which fuse PAX3 and PAX7, respectively, with FKHR to produce chimeric genes. ERMS is frequently associated with loss of heterozygosity of 11p15.5. We investigated seven RMS (three ARMS and four ERMS) by means of cytogenetic, fluorescence in situ hybridization, and molecular analyses, including the study of the main genes implicated in the G1- to S-phase cell cycle transition, and correlated these studies with pathologic findings and clinical outcome. All tumors showed clonal, numerical, and structural chromosomal abnormalities. Two ARMS had the t(2;13)(q35;q14) and the third a PAX7/FKHR fusion, a cryptic t(1;13)(p36;q14), undetected by cytogenetic techniques, but revealed by reverse transcriptase polymerase chain reaction. One ERMS showed a der(11)t(3;11)(p21;p15) as a sole structural anomaly. Gene amplification was seen in four tumors, as double minutes or in the form of homogeneously staining regions. Overexpression of MYCN oncogene was found in two ARMS; N-myc DNA probe detected oncogene amplification located on the double minutes of these cases. Analysis of the regulatory genes responsible for G1- to S-phase transition showed a homozygous deletion of the 9p21 locus genes in a spindle-cell ERMS.
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PMID:Cytogenetic and molecular findings related to rhabdomyosarcoma. An analysis of seven cases. 1285 Mar 75

Genetic alterations occurring on human chromosome arm 1p are common in many types of cancer including lung, breast, neuroblastoma, pheochromocytoma, and colorectal. The identification of tumour suppressors and oncogenes on this arm has been limited by the low resolution of current technologies for fine mapping. In order to identify genetic alterations on 1p in small-cell lung carcinoma, we developed a new resource for fine mapping segmental DNA copy number alterations. We have constructed an array of 642 ordered and fingerprint-verified bacterial artificial chromosome clones spanning the 120 megabase (Mb) 1p arm from 1p11.2 to p36.33. The 1p arm of 15 small-cell lung cancer cell lines was analysed at sub-Mb resolution using this arm-specific array. Among the genetic alterations identified, two regions of recurrent amplification emerged. They were detected in at least 45% of the samples: a 580 kb region at 1p34.2-p34.3 and a 270 kb region at 1p11.2. We further defined the potential importance of these genomic amplifications by analysing the RNA expression of the genes in these regions with Affymetrix oligonucleotide arrays and semiquantitative reverse transcriptase-polymerase chain reaction. Our data revealed overexpression of the genes HEYL, HPCAL4, BMP8, IPT, and RLF, coinciding with genomic amplification.
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PMID:Genomic and gene expression profiling of minute alterations of chromosome arm 1p in small-cell lung carcinoma cells. 1578 53

A valuable diagnostic adjunct and important prognostic parameter in alveolar rhabdomyosarcoma (ARMS) is the identification of translocations t(2;13)(q35;q14) and t(1;13)(p36;q14), and the associated PAX3-FKHR and PAX7-FKHR fusion transcripts, respectively. Most RMS fusion gene type studies have been based on reverse transcriptase-polymerase chain reaction (RT-PCR) detection of the fusion transcript, a technique limited by RNA quality and failure of devised primer sets to detect unusual variants. As an alternative approach, we developed a fluorescence in situ hybridization (FISH) assay that can: (1) distinguish between the two most common ARMS-associated fusion genes; (2) identify potential unusual variant translocations; (3) assess histologic components in mixed alveolar/embryonal RMS; and (4) be performed on paraffinized tissue. FISH analyses of 75 specimens (40 ARMS, 16 ERMS, 8 mixed ARMS/ERMS, and 11 non-RMS tumors) using selected cosmid clone, bacterial, P1-derived, and yeast artificial chromosome probe sets were successful in all but two cases. Among specimens with informative results for both FISH and RT-PCR or standard karyotyping, PAX/FKHR classification results were concordant in 94.6% (53/56). The three discordant cases included one exhibiting a t(2;13) by FISH that was subsequently confirmed by repeat RT-PCR, a second showing a rearrangement of the PAX3 locus only (consistent with the presence of a PAX3 variant translocation), and a third revealing a t(2;13) by FISH that lacked this translocation cytogenetically. Both alveolar and embryonal components of the mixed ARMS/ERMS subtype were negative for PAX3, PAX7, and FKHR rearrangements, a surprising finding confirmed by RT-PCR and/or conventional karyotyping. These data demonstrate that FISH with newly designed probe sets is a reliable and highly specific method of detecting t(1;13) and t(2;13) in routinely processed tissue and may be useful in differentiating ARMS from other small round cell tumors. The findings also suggest that FISH may be a more sensitive assay than RT-PCR in some settings, capable of revealing variant translocations.
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PMID:Use of a novel FISH assay on paraffin-embedded tissues as an adjunct to diagnosis of alveolar rhabdomyosarcoma. 1660 81

Long-term use of antiretroviral nucleoside reverse transcriptase inhibitors (NRTIs) as therapy for human immunodeficiency virus-1 (HIV-1) infection is limited by mitochondrial toxicity. Here we document mitochondrial pathology during the long-term culture of human HeLa cells in the presence or absence of the NRTI Zidovudine(R) (AZT, 800 muM) for up to 77-passages (p), with samples taken at early (p5-p11), middle (p36 and p37), and late (p70-p77) passages. Samples were analyzed for changes in mitochondrial morphology, mitochondrial (mt)DNA quantity, nuclear and mitochondrial gene expression, and mitochondrial membrane potential. Mitochondria showed abnormal proliferation at p5 and abnormal morphology >/=p36. mtDNA quantity was increased at p5 and p11, and 65% depleted at p71. Hierarchical clustering of nuclear gene expression, examined at p37 by the NCI cDNA microarray in AZT-exposed cells, showed down-regulation of 13 out of 16 lipid-metabolizing genes, and up-regulation of most oxidative phosphorylation (OXPHOS) genes. OXPHOS genes encoded by mtDNA, examined at p5, p36, and p75 using the Mitochondrial Gene Mini Array, revealed up-regulation of genes coding for polypeptides of NADH dehydrogenase, ATP synthase, and cytochrome c oxidase. Mitochondrial membrane potential, monitored by JC1 staining, was elevated at p10 and p32, and essentially completely absent at p71. The data show that during chronic exposure of HeLa cells to AZT, a compensatory response was induced at the earlier passages (p5-p37), and by p71 there was widespread mitochondrial morphological damage, severe mtDNA depletion, and a substantial loss of mitochondrial membrane potential.
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PMID:Morphological and molecular course of mitochondrial pathology in cultured human cells exposed long-term to Zidovudine. 1689 29


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