Myb and Ets proteins cooperate in transcriptional activation of the mim-1 promoter.

AUTOR(ES)

Dudek, H

RESUMO

In the generation of the acutely transforming avian retrovirus E26, both myb and ets genes have been transduced, leading to the production of a Gag-Myb-Ets fusion protein. This co-occurrence of v-myb and v-ets oncogenes suggests that the two might have a functional relationship. To look for such a relationship, we tested the transcriptional activation activity of Myb alone or with coexpressed Ets-1 or Ets-2. Using the promoter of the v-Myb-inducible mim-1 gene as a target, we found that full-length c-Myb gene products were poor activators of transcription, while an oncogenic (truncated) form of this protein was a strong trans-activator. However, coexpression of Ets-2 with full-length or truncated forms of Myb greatly increased trans-activation. Coexpression of Ets-1, Fos, Jun, or Myc with Myb did not increase trans-activation of the mim-1 promoter. The ability of Myb and Ets-2 to transactivate was cooperative, since Ets-2 alone gave little or no activation. Bacterially synthesized Ets-2 protein was found to bind specifically to the mim-1 promoter, suggesting that it may be a target for both Myb and Ets proteins. Thus, Myb and Ets proteins can cooperate in transcriptional activation, and their co-occurrence in the E26 virus may reflect a functional relationship between these two oncoproteins. Truncated forms of Myb may have a reduced need for cooperating factors such as Ets-2, and this might constitute an important mechanism associated with oncogenic activation.

Documentos Relacionados

• v-Myb Mediates Cooperation of a Cell-Specific Enhancer with the mim-1 Promoter
• Synergistic activation of the chicken mim-1 gene by v-myb and C/EBP transcription factors.
• Interaction of C/EBPbeta and v-Myb is required for synergistic activation of the mim-1 gene.
• C/EBP, c-Myb, and PU.1 cooperate to regulate the neutrophil elastase promoter.
• Serum, AP-1 and Ets-1 stimulate the human ets-1 promoter.