The glioma-amplified sequence 41 gene (GAS41) is a direct Myb target gene.
The retroviral oncogene v-myb encodes a transcription factor (v-Myb) which transforms myelomonocytic cells in vivo and in vitro. It is thought that v-Myb exerts its biological effects by deregulating the expression of specific target genes, most of which are still unknown. The chicken glioma-amplified sequence 41 gene (GAS41) is located immediately downstream of the lysozyme gene, a known Myb-regulated gene. The GAS41 promoter colocalizes with a CpG island which also functions as an origin of replication. Since the GAS41 promoter contains several potential Myb-binding sites (MBSs) we have investigated whether GAS41 is a v-Myb target gene. Our results show that the GAS41 gene is directly activated by a v-Myb/estrogen receptor fusion protein. Furthermore, our studies reveal that the GAS41 promoter is stimulated by v-Myb in co-transfection experiments and that the DNA-binding activity of v-Myb is crucial for transactivation of the promoter. Electrophoretic mobility-shift assays (EMSA) indicate that several Myb-binding sites, residing approximately 250 bp upstream of the transcriptional start site, are bound by Myb in vitro. Furthermore, chromatin immunoprecipitation assays demonstrate that v-Myb is bound to the GAS41 promoter in vivo. Taken together these findings identify the GAS41 gene as a novel v-Myb target gene. We have also analysed the GAS41 replication origin in myelomonocytic cells and have failed to observe significant differences in origin activity in cells expressing or not expressing v-Myb.
Braas
Daniel
D
Institut für Biochemie, Westfälische Wilhelms-Universität Münster, Wilhelm-Klemm Str.2, D-48149 Münster, Germany.
Gundelach
Holger
H
Klempnauer
Karl-Heinz
KH
D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D002460:Cell Line; D002645:Chickens / Q000235:genetics; D008969:Molecular Sequence Data; D020626:Oncogene Proteins v-myb / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000378:metabolism; D018741:Replication Origin; D014157:Transcription Factors / Q000096:biosynthesis / Q000235:genetics*; D015533:Transcriptional Activation
D020626:Oncogene Proteins v-myb; D012333:RNA, Messenger; D014157:Transcription Factors