Synergistic activation of the chicken mim-1 gene by v-myb and C/EBP transcription factors.
The retroviral oncogene v-myb encodes a transcriptional activator which is responsible for the activation of the mim-1 gene in myelomonocytic cells transformed by v-myb. The mim-1 promoter contains several myb consensus binding sites and has previously been shown to be regulated directly by v-myb. Here we report that the mim-1 gene is activated synergistically by v-myb and different C/EBP transcription factors. We have cloned a chicken C/EBP-related gene that is highly expressed in myeloid cells and identified it as the chicken homolog of C/EBP beta. A dominant-negative variant of chicken C/EBP beta interferes with the v-myb induced activation of the mim-1 gene in these cells, suggesting that C/EBP beta or another C/EBP transcription factor is required for the activation of mim-1 by v-myb. We found that C/EBP beta and other C/EBP transcription factors confer to fibroblasts the ability to induce the mim-1 gene in the presence of v-myb. Finally we show that, in contrast to v-myb, c-myb synergizes with C/EBP transcription factors only at low concentrations of c-myb protein. Our results suggest a role for C/EBP beta, and possibly for other C/EBP transcription factors, in v-myb function and in myeloid-specific gene activation.
Hans-Spemann-Laboratory, Max-Planck-Institute for Immunobiology, Freiburg, Germany.
O
O
Burk
S
S
Mink
M
M
Ringwald
K H
KH
Klempnauer
D000123:Acetyltransferases; D000595:Amino Acid Sequence; D000818:Animals; D009189:Avian Myeloblastosis Virus; D001483:Base Sequence; D022762:CCAAT-Enhancer-Binding Proteins; D002460:Cell Line; D002645:Chickens; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005786:Gene Expression Regulation; D051379:Mice; D008969:Molecular Sequence Data; D009113:Muramidase / Q000235:genetics; D009687:Nuclear Proteins / Q000378:metabolism*; D009838:Oligodeoxyribonucleotides; D020626:Oncogene Proteins v-myb; D011401:Promoter Regions, Genetic; D011506:Proteins / Q000235:genetics* / Q000378:metabolism; D051381:Rats; D015682:Retroviridae Proteins, Oncogenic / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors / Q000378:metabolism*; D015533:Transcriptional Activation
D022762:CCAAT-Enhancer-Binding Proteins; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D009838:Oligodeoxyribonucleotides; D020626:Oncogene Proteins v-myb; D011506:Proteins; D015682:Retroviridae Proteins, Oncogenic; D014157:Transcription Factors; D000123:Acetyltransferases; C077509:mim-1 protein, Gallus gallus; D009113:Muramidase