Weak transcriptional activation is sufficient for transformation by v-Myb.
The v-myb oncogene causes monoblastic leukemia in chickens and transforms avian myelomonocytic cells in vitro, v-Myb is a short-lived nuclear protein which binds to DNA in a sequence-specific manner and can activate gene expression in transient DNA transfections. Analysis of a series of v-Myb mutants has shown that the ability to activate transcription appears to be required for leukemic transformation. We have systematically investigated transcriptional activation by v-Myb and have made several new observations: (i) v-Myb is a very weak activator when compared to GAL4; (ii) very weak transcriptional activation by v-Myb is sufficient for transformation, whereas very strong transcriptional activation by a v-Myb-VP16 fusion protein is not; and (iii) v-Myb can activate transcription by two genetically distinct mechanisms, only one of which requires the presence of Myb-binding sites.
Engelke
U
U
Department of Pathology, Stanford University School of Medicine, California 94305-5324, USA.
Whittaker
L
L
Lipsick
J S
JS
D017501:Adenovirus E1B Proteins / Q000235:genetics; D009189:Avian Myeloblastosis Virus / Q000235:genetics; D002460:Cell Line; D002471:Cell Transformation, Neoplastic / Q000235:genetics*; D002472:Cell Transformation, Viral / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000502:physiology; D005347:Fibroblasts; D005656:Fungal Proteins / Q000235:genetics / Q000502:physiology; D017405:Herpes Simplex Virus Protein Vmw65 / Q000235:genetics / Q000502:physiology; D020626:Oncogene Proteins v-myb; D009857:Oncogenes / Q000235:genetics*; D011401:Promoter Regions, Genetic / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000502:physiology; D015682:Retroviridae Proteins, Oncogenic / Q000235:genetics* / Q000502:physiology; D029701:Saccharomyces cerevisiae Proteins; D017384:Sequence Deletion / Q000502:physiology; D016385:TATA Box / Q000235:genetics; D013937:Thymidine Kinase / Q000235:genetics; D015534:Trans-Activators / Q000235:genetics / Q000502:physiology; D014157:Transcription Factors; D015533:Transcriptional Activation / Q000235:genetics*; D014162:Transfection
D017501:Adenovirus E1B Proteins; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; C052130:GAL4 protein, S cerevisiae; C070633:Gal-VP16; D017405:Herpes Simplex Virus Protein Vmw65; D020626:Oncogene Proteins v-myb; D011993:Recombinant Fusion Proteins; D015682:Retroviridae Proteins, Oncogenic; D029701:Saccharomyces cerevisiae Proteins; D015534:Trans-Activators; D014157:Transcription Factors; D013937:Thymidine Kinase