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)

Derived from the susceptible AKR.H-2bSL1 tumor cell line, a variant tumor subclone, cl.18-5, was selectively insusceptible to H-2-restricted anti-AKR/Gross virus cytotoxic T lymphocytes (CTL) due to its failure to be recognized. In this study, the expression of virus-related products by variant cl.18-5 cells was compared to that of AKR.H-2bSL1 cells and a susceptible clone, as an approach towards defining the virus-associated antigens recognized by anti-AKR/Gross virus CTL. Despite the type specificity of the CTL, cl.18-5 displayed normal levels of the group-specific antigen (gag) encoded proteins p30, p15, p12 and p10, and the gag-associated Gross cell surface antigen. These results were confirmed by fluorescence-activated cell sorter analysis employing monoclonal antibodies specific for either AKR p12 or the cell surface glycosylated form of AKR ecotropic gag product. In contrast, cl.18-5 was variably less sensitive than AKR.H-2bSL1 to the action of complement and xenogeneic antisera directed against the envelope (env) product gp70. In addition, a panel of five monoclonal antibodies to gp70, which detect distinct endogenous ecotropic viral determinants, lysed AKR.H-2bSL1, but not cl.18-5 cells. However, absorption experiments indicated that cl.18-5 did express near normal levels of these specificities, suggesting an alteration in the orientation or topographical distribution of these determinants. Consistent with an inappropriate display of env products, cl.18-5 was found to be deficient in the production of infectious ecotropic leukemia virus. The particulate fraction of the cell-free supernatant of cl.18-5 contained normal levels of reverse transcriptase activity, indicating that noninfectious viral particles were being produced. Collectively, these results point to an association between recognition by anti-AKR/Gross virus CTL and the expression of ecotropic gp70 required for infectivity of virus.
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PMID:The specificity of H-2-restricted cytotoxic T lymphocytes directed to AKR/Gross leukemia virus-induced tumors. II. Altered gp70 display and production of noninfectious virus particles by an insusceptible variant tumor. 619 7

The FBR murine osteosarcoma virus complex induces bone tumors with a similar latency and pathology to those induced by the FBJ virus complex. FBR murine sarcoma virus ( FBR -MSV) has been isolated from its helper virus(es) by the establishment of transformed nonproducer cells. These cells were found to express a 75,000-Da protein (P75) which was antigenically related to the p55 oncogene product of the FBJ murine osteosarcoma virus ( FBJ -MSV). P75 also contained antigenic determinants of murine leukemia virus (MLV) gag gene p15, p12, and p30 proteins, and is therefore a gag- fos fusion protein ( P75gag - fos ). P75gag - fos is a phosphoprotein and is found primarily in the nucleus. Only a single species of RNA, of 3.3 kb, was identified in FBR -MSV-transformed nonproducer cells using both fos and MLV probes, which suggested that P75gag - fos was expressed from genome-sized RNA. Chromosomal DNA from one nonproducer cell line was found to contain a single EcoRI restriction fragment of 12 kb pairs (kbp) which encompassed the FBR -MSV provirus. This DNA fragment was molecularly cloned into bacteriophage Charon 30 (lambda FBR -1), and a 7.5-kbp HindIII restriction fragment containing the entire provirus was subsequently subcloned into pBR322 ( pFBR -1). DNA from pFBR -1 was capable of inducing morphological transformation of mouse and rat fibroblasts in tissue culture. In addition, transfected cells expressed the FBR -MSV P75gag - fos protein.
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PMID:FBR murine osteosarcoma virus. I. Molecular analysis and characterization of a 75,000-Da gag-fos fusion product. 620 14

Monoclonal antibodies were prepared from mice and rats immunized with Friend leukaemia virus and BALB/c xenotropic virus. By immunoprecipitation of 125I-labelled and [35S]methionine-labelled viruses and by protein blotting, ten antibodies were found to react with the viral components p12, p15, p30, gp70 and p15E/p12E. A dot-immunobinding assay was found to be a reliable method to type the antibody reactivity with different murine leukaemia viruses (MuLVs). When tested on a panel of ecotropic and xenotropic MuLVs the antibodies revealed the following antigenic specificities: ecotrop-specific on p15E/p12E; xenotrop-specific on p15E; group-specific on p30 and p15E; FM-specific on gp70; FR-specific on gp70 and p15. Of particular interest is a cytotoxic antibody recognizing an FMR determinant localized on p12.
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PMID:Monoclonal antibodies recognizing structural components of murine retroviruses including an FMR antigen on protein p12. 620 1

We have analyzed the RNA genome of RadLV/VL3, a highly oncogenic murine leukemia virus. This virus is produced by a permanent cell line derived from a radiation leukemia virus-induced thymic lymphoma of C57BL/Ka mice. Two distinct RNA components were found in the virions: a 70S dimer containing two 8 kb RNA subunits and a 54S dimer containing two 5.6 kb RNAs. A nononcogenic retrovirus, BL/Ka(B), endogenous in the same strain of mice, contains only 8 kb viral RNA subunits. The linkages between both RadLV/VL3 dimers have identical thermal stabilities. Both dimers can serve as primer templates for reverse transcriptase and both produce very similar "strong-stop" cDNAs 147 +/- 1 bases long. Sequences at the 5' end of the 5.6 kb subunit contain the genes for the viral proteins p15 and p12, but the gene for p30 is either absent or partially deleted. In vitro translation of the 5.6 kb RNA yields a 100,000 molecular weight protein containing antigenic determinants which react with antibody to p15 but not with antibody to p30. In addition, cells producing RadLV/VL3 virus synthesize a novel of 1.6 kb poly(A)-containing cytoplasmic RNA which shows very little if any homology with BL/Ka(B) viral sequences.
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PMID:Radiation leukemia virus contains two distinct viral RNAs. 624 93

Polyproteins encoded by several independent isolates of feline sarcoma virus (FeSV) were analyzed with respect to molecular weight, extent of phosphorylation, and tryptic peptide composition. As previously reported, cells nonproductively transformed by the Gardner strain of FeSV express a polyprotein which has a molecular weight of approximately 115,000 and contains feline leukemia virus p15, p12, and minor portion of p30. In addition, a major 72,000-dalton possible cleavage product can be identified. Snyder-Theilen FeSV-transformed cells express a major polyprotein of approximately 115,000 daltons and a second highly related 80,000-dalton protein. The p12 structural component of Gardner FeSV P115, but not Snyder-Theilen FeSV 115, corresponds to feline leukemia virus subgroup A with respect to immunological type specificity, a finding consistent with the independent origin of these viruses. Tryptic peptide analysis revealed five methionine-containing peptides specific to the nonstructural portion of Gardner FeSV 115, three of which were also represented in Snyder-Theilen FeSV P115, three of which were also represented in Snyder-Theilen FeSV P115. None of these [35S]methionine-labeled tryptic peptides were present in translational products representative of the complete feline leukemia virus subgroup A genome, including Pr180gag-pol, Pr65gag, and Pr82env. Similarly phosphorylated tryptic peptides within the structural (p12) and nonstructural components of Gardner FeSV P115 and Snyder-Theilen FeSV P115 Are highly related. These findings support the possibility that acquired sequences of two independently derived isolates of FeSV encode structurally related proteins.
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PMID:Translational products encoded by newly acquired sequences of independently derived feline sarcoma virus isolates are structurally related. 624 59

Several independent isoltes of feline sarcoma virus (FeSV) have been described. Such viruses are apparently derived by genetic recombination between feline leukaemia virus (FeLV) genomic RNA and host cellular genetic sequences with transforming potential. Two FeSV isolates, one originally described by Gardner and the second by Snyder-Theilen, have been shown to encode polyproteins of around 115,000 molecular weight. Both polyproteins contain FeLV structural components (p15, p12) at their amino terminus in addition to nonstructural carboxyl terminal components encoded by acquired sequences within the FeSV genome. We have previously shown that Gardner FeSV P115 contains multiple sites of phosphorylation within its nonstructural component and possesses an associated protein kinase activity. In the present study we describe the expression in cells derived from a number of mammalian species, of a highly conserved celklular phosphoprotein with binding affinity for Gardner FeSV P115. This protein, designated P150, exhibits an associated protein kinase activity and is immunologically and structurally distinct from polyproteins encoded by the Gardner or Snyder-Theilen strains of FeSV.
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PMID:Feline sarcoma virus polyprotein P115 binds a host phosphoprotein in transformed cells. 625 64

Murine leukemia viruses isolated from radiation-induced BALB/c leukemias were characterized with respect to viral proteins and RNA. Analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the viral structural proteins revealed that for p12, p15, p30, and gp70, three of four electrophoretic variants of each could be detected. There was no correlation found between any of these mobilities and N- or B-tropism of the viruses. Proteins of all xenotropic viral isolates were identical in their gel electrophoretic profiles. The similar phenotypes of multiple viral clones from individual leukemias and of isolates grown in different cells suggest that the polymorphism of ecotropic viruses was generated in vivo rather than during in vitro virus growth. By two-dimensional fingerprinting of RNase T1-resistant oligonucleotides from 70S viral DNA, the previously reported association of N- and B-tropism with two distinct oligonucleotides was confirmed. The presence of two other oligonucleotides was correlated with positive and negative phenotypes of the virus-coded GIX cell surface antigen. The RNAs of two B-tropic isolates with distinctive p15 and p12 phenotypes differed from the RNA of a prototype N-tropic virus by the absence of three oligonucleotides mapping in the 5' portion (gag region) of the prototype RNA. In addition, one small-plaque B-tropic virus displayed extensive changes in the RNA sequences associated with the env region of the prototype.
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PMID:Biochemical analysis of murine leukemia viruses isolated from radiation-induced leukemias of strain BALB/c. 625 Dec 40

In this study, we demonstrated the expression of a 170,000-Mr polyprotein in each of several McDonough feline sarcoma virus (FeSV)-transformed mink cell clones and one McDonough FeSV-transformed rat clone. This polyprotein designated McDonough FeSV P170, contained feline leukemia virus (FeLV) p15, p12, and p30 immunological determinants and shared two of its five [35S]methionine-labeled tryptic peptides with FeLV Pr180gag-pol. Both of these peptides were shown to be specific to the p30 component of Pr180gag-pol. The remaining McDonough FeSV P170 methionine-containing peptides were not represented within either FeLV Pr180gag-pol or Pr82env. Of interest, of the three peptides specific to the nonstructural component of McDonough FeSV P170, one was also represented in the 115,000-Mr polyproteins encoded by the Gardner and Snyder-Theilen strains of FeSV. These findings raise the possibility that the nonstructural components of polyproteins encoded by each of the three independently derived feline transforming viruses contained both common and unique regions. Moreover, if the sequences encoding these components are involved in transformation, as appears to be the case, our findings establish that the position of their insertion within the gag-pol region of the FeLV genome can vary among individual isolates.
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PMID:Characterization of a 170,000-dalton polyprotein encoded by the McDonough strain of feline sarcoma virus. 625 Dec 65

Naturally occurring oncoviruses of several species are transmitted contagiously and cause lymphosarcoma (LSA) or leukaemia in their hosts. All naturally occurring oncoviruses replicate in vivo in the tumours they induce or, as with bovine leukaemia virus, can be isolated from tumour cells grown in short-term cell culture. However, we have shown that feline leukemia virus (FeLV) is not present in a significant minority of pet cats that develop LSA. Unlike experimentally induced virus-negative leukaemias and sarcomas of other species, LSA cells from FeLV-negative LSA cats lack any FeLV proteins, including p15 or p12, and complete functional copies of FeLV provirus and thus do not produce FeLV when grown in cell culture. Thus, except for FeLV, the naturally occurring animal leukaemogenic oncoviruses seem to induce only virus-producing lymphoid tumours. Our earlier findings prompted a study to determine the frequency of occurrence of FeLV non-producer (NP) LSA in pet cats and whether NP LSAs develop in cats exposed to FeLV. We report here epidemiological data which indicate that development of NP LSAs in pet cats is associated with exposure to FeLV and suggest that FeLV may be the aetiological agent for FeLV NP feline LSAs. Thus, feline NP LSAs may be suitable for studying the potential viral aetiology and mechanism of leukaemogenesis of human lymphoid tumours in which no oncoviruses have, as yet, been proved to cause the disease.
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PMID:Development of virus non-producer lymphosarcomas in pet cats exposed to FeLv. 625 21

The only known product of the Snyder-Theilen strain of feline sarcoma virus (ST-FeSV) is a 85,000-dalton protein, designated ST P85, that contains feline leukemia virus gag gene encoded proteins (p15, p12, and a fragment of p30) and a sarcoma virus-specific polypeptide. Antibodies directed against the latter immunoprecipitated a 92,000-dalton phosphoprotein (NCP 92) expressed at low levels in normal feline embryo fibroblasts as well as in feline cells of epithelial or lymphoid origin. Normal cellular proteins crossreactive with ST P85 were also detected in cell lines from various other mammalian species. These results suggest that the ST-FeSV sequences encoding for the sarcoma virus-specific domain of ST P85 originated from an evolutionarily conserved cellular gene expressed in cells of independent differentiation lineage. Immunoprecipitates containing ST-FeSV P85 exhibited a protein kinase activity that specifically phosphorylated tyrosine residues. The physiological significance of this finding is illustrated by the finding that phosphotyrosine is an intrinsic component of ST P85. Furthermore, 5- to-fold higher levels of this unusual phosphorylated amino acid were present in ST-FeSV transformants than in uninfected control cells. Phosphorylation of tyrosine residues appears to be associated with cellular transformation caused by Rous sarcoma virus and Abelson murine leukemia virus. Thus, independent transforming virus isolates from birds, mice, and cats may utilize common pathways in exerting their oncogenic potential.
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PMID:Origin and functional properties of the major gene product of the Snyder-Theilen strain of feline sarcoma virus. 625 60


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