A temperature-sensitive phenotype of avian myeloblastosis virus: determinants that influence the production of viral mRNAs

Schirm, Sabine; Moscovici, G; Bishop, J. Michael

doi:10.1128/jvi.64.2.767-773.1990

Cited by 12 publications

(9 citation statements)

References 25 publications

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“…This argument is supported by the fact that even in our MuSV-124 deletion mutants capable of only trace levels of splicing (e.g., BX, NX, and AX), what splicing there was appeared to be thermosensitive. Moreover, the splicing of avian myeloblastosis virus RNA has also been shown to be temperature dependent (27), although not to the degree shown by MuSVts11O.…”

Section: Discussionmentioning

confidence: 97%

Activation of cryptic splice sites in murine sarcoma virus-124 mutants

Mars

Cizdziel

Murphy

1990

J Virol

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We have examined splice site activation in relation to intron structure in murine sarcoma virus (MuSV)-124 RNA. MuSV-124 contains inactive murine leukemia virus env gene splice sites (termed 5' env and 3' env) as well as cryptic sites in the gag and v-mos genes (termed 5' gag and 3' mos) which are activated for thermosensitive splicing by a 1,487-base intronic deletion in the MuSV-124 derived MuSVtsllO retrovirus. To determine conditions permissive for splice site activation, we examined MuSV-124 mutants deleted in the 1,919-base intron bounded by the 5' gag and 3' mos sites. Several of these deletions activated thermosensitive splicing either at the same sites used in MuSVtsllO or in a previously unreported temperature-sensitive splice event between the 5' gag and 3' env sites. These data suggested that the thermosensitive splicing phenotype characteristic of MuSVts110 required neither a specialized intron nor selection of a particular 3' splice site. The 3' env and 3' mos sites were found to compete for splicing to the 5' gag site; the more upstream 3' env site was exclusively used in MuSV-124 mutants containing both sites, whereas selection of the 3' mos site required removal of the 3' env site. Branchpoint sequences were found to have a potential regulatory role in thermosensitive splicing. Insertion of a beta-globin branchpoint sequence in a splicing-inactive MuSV-124 mutant activated efficient nonthermosensitive splicing at the 3' mos site, whereas a mutated branchpoint activated less efficient but thermosensitive splicing.

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Section: Discussionmentioning

confidence: 97%

Activation of cryptic splice sites in murine sarcoma virus-124 mutants

Mars

Cizdziel

Murphy

1990

J Virol

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“…The in vivo consequences of this difference with respect to transformation by v-Myb are hard to predict. As v-Myb has a higher affinity for DNA than does c-Myb (20), the elevated amounts of v-Myb necessary for transformation (21) might be expected to bind most or all of those sequences recognised by c-Myb. The increased binding specificity of v-Myb over c-Myb observed here does not support the theory that AMV v-Myb binds an additional spectrum of transformationspecific sites.…”

Section: Discussionmentioning

confidence: 99%

Extension of the DNA binding consensus of the chicken c-Myb and v-Myb proteins

Weston

1992

Nucl Acids Res

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The chicken c-myb gene and the v-myb oncogene transduced by avian myeloblastosis virus (AMV) encode DNA binding transcription activators. The DNA binding domain of AMV v-Myb displays a number of amino acid changes relative to c-Myb; v-Myb proteins in which one or more of three crucial residues in the DNA binding domain are mutated to resemble the c-Myb sequence display altered transformation phenotypes. In order to establish whether the spectrum of DNA binding sites which AMV v-Myb can recognise is different from that seen by chicken c-Myb, a site selection protocol was used to derive consensus binding sequences for three variant Myb proteins made in vitro, and also using nuclear extract from the v-myb transformed cell line BM2. The results show that the original consensus binding site defined for v-Myb, YAA-CKG, can be extended to YAACKGHH, and that this new consensus holds for both v-Myb and chicken c-Myb.

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“…A temperature-sensitive mutant of AMV has been previously reported (30). However, this mutant is somewhat difficult to work with and the basis for its temperature sensitivity remains unclear (37). Temperature-sensitive mutants of the E26 leukemia virus, which contains both the v-myb and v-ets onco-genes, have been isolated and analyzed in considerable detail (3,4).…”

mentioning

confidence: 99%

Cells transformed by a v-Myb-estrogen receptor fusion differentiate into multinucleated giant cells

Engelke

Wang

Lipsick

1997

J Virol

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In order to make conditional alleles of the v-myb oncogene, we constructed and tested avian retroviruses which produce a number of different fusion proteins between v-Myb and the human estrogen receptor (ER). We found that the portion of the ER used in making these fusions profoundly affected their transcriptional activation. However, all the fusions tested were only weakly transforming in embryonic yolk sac assays and there was no direct correlation between the level of transcriptional activation and strength of oncogenic transformation. Nevertheless, transformation by a v-Myb-ER fusion was estrogen dependent, and upon withdrawal of the hormone, monocytic-lineage cells differentiated into multinucleated giant cells. Surprisingly, the withdrawal of estrogen caused a dramatic increase in the stability of the fusion protein, although it remained unable to promote cell growth or block differentiation.

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A temperature-sensitive phenotype of avian myeloblastosis virus: determinants that influence the production of viral mRNAs

Cited by 12 publications

References 25 publications

Activation of cryptic splice sites in murine sarcoma virus-124 mutants

Activation of cryptic splice sites in murine sarcoma virus-124 mutants

Extension of the DNA binding consensus of the chicken c-Myb and v-Myb proteins

Cells transformed by a v-Myb-estrogen receptor fusion differentiate into multinucleated giant cells

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