UMLS:C0679427 - FACTA Search

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

Query: UMLS:C0679427 (myeloblastosis)
982 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

An intact 5.7-kb provirus of the avian erythroblastosis virus E26 has been molecularly cloned for comparisons with avian myeloblastosis virus (AMV) and other avian tumor viruses. E26 and AMV transform hemopoietic cells exclusively. Both cause myeloblastosis, but E26 also causes erythroblastosis. Sequence analysis of the proviral DNA showed that: The tripartite transforming gene of E26 forms a contiguous reading frame of 1046 codons, including 272 gag, 283 mybE, and 491 ets codons. No subgenomic ets-specific mRNA was detected in E26-infected cells. By contrast, the onc gene of AMV consists almost entirely of a mybA sequence expressed via subgenomic mRNA that extends over the 5' and 3' ends of mybE. mybE is only slightly diverged from the mybA homolog of AMV and even less from the cellular proto-myb sequence with no characteristic mutation that sets apart the two viruses from proto-myb. The U5 region of the long terminal repeat (LTR) of E26 and AMV are colinear and differ only in scattered point mutations. The U3 region of the E26 LTR is different from that of AMV but is colinear and closely related with that of avian carcinoma virus MH2 and also with that of Prague Rous sarcoma virus (RSV), except for an unexpected 16-nucleotide substitution of 22 RSV nucleotides. Upstream of the 3' LTR, the c region of E26 appears to be the same as that of RSV for 70 nucleotides and very similar to those of AMV and MH2 for about 20 to 30 nucleotides. Since the U3s of E26, MH2 and RSV are very closely related and neither MH2 nor RSV show a particular erythroblast tropism, it is possible that the U3 does not play a critical role in the erythroblast tropism of E26. Electrophoretic size analyses of chicken DNA digested with restriction enzymes indicate that DNA fragments totaling over 50 kb hybridize with viral ets DNA.
...
PMID:Avian erythroblastosis virus E26: nucleotide sequence of the tripartite onc gene and of the LTR, and analysis of the cellular prototype of the viral ets sequence. 609 27

The secondary structure of avian myeloblastosis virus (AMV) RNA was characterized by electron microscopy under moderately denaturing spreading conditions. Under denaturation by aqueous 44% formamide or 77% formamide in the presence of salts, partly stretched RNA molecules with measurable double-stranded regions were observed. This approach allowed the localization from 5 to 11 regions of preserved secondary structure on AMV RNA molecules. Topographic analysis revealed a nonrandom occurrence of stable secondary structures in several prevalent regions. These regions with higher secondary structure stability revealed certain similarity to hairpin structures localized by electron microscopy on Rous sarcoma virus RNA or to highly structured regions found on this RNA by T1 ribonuclease oligonucleotide analysis.
...
PMID:Studies on the structure of avian myeloblastosis virus (AMV) RNA. III. Electron microscopic definition of secondary structure. 612 7

Structural properties of the 60-70S RNA complex of avian myeloblastosis virus (AMV) were analysed in electron microscope after treatment under a set of non-denaturing, gently and strongly denaturing conditions. By selected denaturing conditions, the significant fraction of 60-70S AMV RNA molecules revealed partially unfolded structures either in a dimer or a more complex form and in a length corresponding to mol. wt. of 5.6 X 10(6). The typical dimers contained a characteristic central structure connecting the subunits and similar to those described for Rous sarcoma virus (RSV) and mammalian retrovirus RNAs. This dimer linkage in the AMV genome occurred at 384 +/- 43 nucleotides from one end of each subunit. Besides partially unfolded complexes, collapsed structures and extended linear molecules were observed. The length of majority of the linear molecules had reached a half of that of the partially unfolded complexes corresponding to the mol. wt. of monomers estimated under conditions of strong denaturation to be 2.8 X 10(6). Based on our findings, we conclude that the genome of AMV shares the dimer structure with RSV and mammalian retroviruses. We also conclude that the secondary structure of AMV RNA molecule is more labile than that of RNA of mammalian retroviruses.
...
PMID:Electron microscopic studies on the structure of 60-70S RNA of avian myeloblastosis virus. 613 36

Reverse transcriptase from Rous sarcoma virus and avian myeloblastosis virus was purified by a rapid two-step procedure using chromatography on phosphocellulose and heparin-Sepharose. The resulting enzyme was homogeneous, had a high specific activity and was free of contaminating nucleases. This procedure has been adapted to small-scale preparation of enzyme from mutant virus containing thermolabile reverse transcriptase, and is equally suitable for large-scale enzyme purification.
...
PMID:Purification of reverse transcriptase from avian retroviruses using affinity chromatography on heparin-sepharose. 616 44

Preparations of the alphabeta and the betabeta forms of reverse transcriptase from the Prague C strain of Rous sarcoma virus grown in chicken embryo fibroblasts, the alphabeta and the betabeta forms of the enzyme from the B77 strain of Rous sarcoma virus grown in duck embryo fibroblasts, and the alphabeta form of reverse transcriptase from avian myeloblastosis virus have been analyzed. All these enzyme preparations contain a Mn(2+) -activated endonuclease activity. The betabeta form of enzyme, in addition, contains a Mg(2+) -dependent endonuclease. Such an activity is barely detectable in the alphabeta form of enzymes. The endonuclease associated with reverse transcriptase introduces single- and double-strand breaks containing 3' OH and 5' P termini into RF I DNA. The conversion of RF I DNA to RF III DNA is more readily catalyzed by the betabeta form of reverse transcriptase. In contrast to a recently published report by Hizi et al. (J. Virol 41:974-981, 1982), we have failed to detect the conversion of RF I DNA to covalently closed relaxed circles (RF IV DNA) by any of the alphabeta form of enzymes tested. RF IV DNA was not produced by the betabeta form of reverse transcriptase either. We conclude that topoisomerization is not an intrinsic activity of reverse transcriptase. Although the conversion of RF I DNA to RF II DNA was found to be rapid, the endonuclease associated with reverse transcriptase acted slowly on RF II, RF III, and RF IV DNAs. Circular and linear single-stranded DNAs were also susceptible to cleavage by the endonuclease at a rate comparable to nicking of RF I DNA. This pattern of activity suggests that the endonuclease cleaves the RF I DNA in the single-stranded regions of the DNA induced by its supercoiling. The preference of the alphabeta and the betabeta forms of the endonuclease for viral DNA was tested with Rous-associated virus type 2 and Rous sarcoma virus transformation-defective Schmidt-Ruppin B strain DNA molecularly cloned in plasmid pBR322 and M13 DNA vectors, respectively. The rate of nicking of RF I DNA containing viral DNA or partial sequences of viral DNA with one or two tandem long terminal repeats was the same as when these sequences were not present in the host vectors. A similar lack of preference was observed with single-stranded M13 DNAs.
...
PMID:Mechanism of action of the endonuclease associated with the alpha beta and beta beta forms of avian RNA tumor virus reverse transcriptase. 618 36

We purified the p19 proteins from the Prague C strain of Rous sarcoma virus, avian myeloblastosis virus, B77 sarcoma virus, myeloblastosis-associated virus-2(0), and PR-E 95-C virus and measured their binding affinities for 60S viral RNA by the nitrocellulose filter binding technique. The apparent association constants of the p19 proteins from Rous sarcoma virus Prague C, avian myeloblastosis virus, and B77 sarcoma virus for homologous and heterologous 60S RNAs were similar (1.5 x 10(11) to 2.6 x 10(11) liters/mol), whereas those of myeloblastosis-associated virus-2(0) and PR-E 95-C virus were 10-fold lower. The sizes and relative amounts of the virus-specific polyadenylic acid-containing RNAs in the cytoplasms of cells infected with Rous sarcoma virus Prague C, myeloblastosis-associated virus-2(0), and PR-E 95-C virus were determined by fractionating the RNAs on agarose gels containing methylmercury hydroxide, transferring them to diazobenzyloxymethyl paper and hybridizing them to a 70-nucleotide complementary DNA probe. In cells infected with Rous sarcoma virus Prague C we detected 3.4 x 10(6)-, 1.9 x 10(6)-, and 1.1 x 10(6)-dalton RNAs, in PR-E 95-C virus-infected cells we detected 3.4 x 10(6)-, 1.9 x 10(6)- and 0.7 x 10(6)-dalton RNAs, and in cells infected with myeloblastosis-associated virus-2(0) we detected 3 x 10(6)- and 1.3 x 10(6)-dalton RNAs. Each of these RNA species contained RNA sequences derived from the 5' terminus of genome-length RNA, as evidenced by hybridization with the 5' 70-nucleotide complementary DNA. The ratios of subgenomic mRNA's to genome-length RNAs in cells infected with myeloblastosis-associated virus-2(0) and PR-E 95-C virus were three- to five-fold higher than the ratio in cells infected with Rous sarcoma virus Prague C. These results suggest that more processing of viral RNA in infected cells is correlated with lower binding affinities of the p19 protein for viral RNA, and they are consistent with the hypothesis that the p19 protein controls processing of viral RNA in cells.
...
PMID:Correlation of RNA binding affinity of avian oncornavirus p19 proteins with the extent of processing of virus genome RNA in cells. 625 34

We demonstrated previously that chicken embryo fibroblasts accumulate approximately 100 copies of embryonic globin RNA after transformation by Rous sarcoma virus. Here we demonstrate that the globin gene in chicken embryo fibroblasts is activated by infection with two other oncogenic retroviruses, avian erythroblastosis virus and strain MC-29 of avian myeloblastosis virus, which contain transforming genes unrelated in nucleotide sequence content to each other or to the Rous sarcoma virus src gene. In addition, we have measured the genetic complexity of transformation by using established techniques for determining the number of different RNA sequences in specific populations of cells. Our results indicate that transformation of chicken embryo fibroblasts by Rous sarcoma virus results in the accumulation of RNA from approximately 1000 average-sized new transcription units.
...
PMID:Activation of cellular genes by avian RNA tumor viruses. 625 77

The RNA of defective avian acute leukemia virus OK10 was isolated from a defective virus particle, released by OK10-transformed nonproducer avian fibroblasts, as a 60S complex consisting of 8.6-kilobase subunits. Oligonucleotide fingerprinting and RNA.cDNA hybridization identified two sets of sequences in OK10 RNA: group-specific sequences, which are related to all nondefective members of the avian tumor virus group, and a sequence closely related to the subgroup-specific sequences (mcv) of the myelocytomatosis virus (MC29) subgroup of avian acute leukemia viruses. Hence, OK10 is classified as a member of the MC29 subgroup of avian tumor viruses, in agreement with classification based on its oncogenic spectrum. The group-specific sequences of OK10 RNA include partial (Delta) pol and env genes, a c-region, and, unlike those of all other members of the MC29 subgroup, a complete gag gene. Oligonucleotide mapping revealed 5'-gag-Deltapol-mcv-Deltaenv-c-3' as the order of the subgroup-specific and group-specific elements of OK10 RNA. The genetic unit gag-Deltapol-mcv, measuring approximately 6.4 kilobases, codes for the nonstructural, presumably transforming, 200,000-dalton OK10-specific protein and also includes the gag gene coding for the internal virion proteins. Because gag is the only intact virion gene shared in addition to regulatory RNA sequences between OK10 and nondefective avian tumor viruses, it is concluded that the gag gene is sufficient for the formation of a defective virus particle. Comparisons among the RNAs and gene products of different viruses of the MC29 subgroup show that they share 5'-terminal gag-related and internal mcv sequences but differ from each other in intervening gag-, pol-, and mcv-related sequences. It follows that the probable transforming genes and their protein products have two essential domains, one consisting of conserved 5' gag-related and the other of 3' mcv-related sequence elements. In the light of this and previous knowledge we can now distinguish two designs among five different transforming onc genes of avian tumor viruses: onc genes with coding sequences unrelated to virion genes, like those of Rous sarcoma virus and avian myeloblastosis virus, and onc genes with coding sequences that are hybrids of virion genes and specific sequences, like those of the MC29 subgroup viruses, of avian erythroblastosis virus, and of Fujinami sarcoma virus.
...
PMID:OK10, an avian acute leukemia virus of the MC 29 subgroup with a unique genetic structure. 626 Dec 41

Functionally differentiated chicken macrophages were derived by in vitro differentiation of embryonic yolk sac cells and were characterized by several macrophage-specific cell markers. Uniform, infected, virus-producing cultures were obtained after exposure of these macrophages to avian myoblastosis virus (AMV), avian myelocytomatosis virus (MC29), myeloblastosis-associated virus (MAV-2), and Prague strain of Rous sarcoma virus (PR-B RSV). Both AMV and MC29 induced morphological transformation typical of the in vivo leukemias induced by these virus strains. Analysis of the expression of macrophage-specific markers in these two transformed cell types demonstrated that different markers of the mature macrophage were suppressed by each virus, even though the parental cell immediately preceding the transformation event was a mature macrophage in both cases. Cells infected with PR-B RSV and MAV-2 showed no observable difference from uninfected macrophages in terms of morphological characteristics, growth rate, or expression of the differentiated functions of macrophages. Ths system provides demonstrations of a cell type that produces infectious, transforming RSV but fails to respond by functional alterations induced by the transforming gene, src.
...
PMID:Differential effects of transforming avian RNA tumor viruses on avian macrophages. 626

Reticuloendotheliosis virus strain T (REV-T) is a highly oncogenic avian retrovirus which causes a rapid neoplastic disease of the lymphoreticular system. Upon infection, this virus gives rise to two species of unintegrated linear viral DNA, which are 8.3 and 5.5 kilobase pairs long and represent the helper virus (REV-A) and the oncogenic component (REV-T), respectively. Restriction endonuclease cleavage maps of these two DNA components indicate that REV-T DNA has a large portion of the genome deleted with respect to REV-A DNA and a substitution about 0.8 to 1.5 kilobase pairs long that is unrelated to REV-A DNA. These additional sequences comprise the putative transforming region of REV-T (rel). A chicken spleen cell line transformed by REV-T produced virus which upon infection gives rise to three species of unintegrated linear viral DNA (8.3, 5.5, and 3,3 kilobase pairs). We isolated the proviruses of the 8.3- and 3.3-kilobase pair species from this cell line by cloning in the phage vector Charon 4A. Restriction enzyme mapping showed that the two proviral clones are proviruses of REV-A and a variant of REV-T, respectively. A subclone of the variant REV-T provirus specific for the rel sequences of REV-T was used as a hybridization probe to demonstrate that the rel sequences are different from the putative transforming sequences of Schmidt-Ruppin Rous sarcoma virus strain A, avain myelocytomatosis virus, avian myeloblastosis virus, avian erythroblastosis virus, Abelson murine leukemia virus, and Friend erythroleukemia virus. In addition, the rel-specific hybridization probe was used to identify a specific set of sequences which are present in uninfected avian DNAs digested with several restriction enzymes. The corresponding cell sequences are not arranged like rel in REV-T.
...
PMID:Characterization of reticuloendotheliosis virus strain T DNA and isolation of a novel variant of reticuloendotheliosis virus strain T by molecular cloning. 627 17

<< Previous 1 2 3 4 5 6 7 Next >>