Interaction between the hematopoietic Ets transcription factor Spi-B and the coactivator CREB-binding protein associated with negative cross-talk with c-Myb.

We have previously shown that the hematopoietic Ets transcription factor PU.1 interacts with the transcriptional coactivator CREB-binding protein (CBP). In this study, we further investigated whether Spi-B, another hematopoietic Ets transcription factor, also interacts with CBP. Direct physical interaction of Spi-B with CBP was demonstrated by glutathione S-transferase binding assay. ...
Analysis using several deletion mutants of Spi-B and CBP revealed that the NH2-terminal region including the activation domain of Spi-B interacted with the region spanning amino acid residues 1283-1915 of CBP in vitro. The interaction of Spi-B with CBP was also observed in vivo. CBP potentiated Spi-B-mediated transcription of the reporter gene driven by the multimerized PU.1/Spi-B binding sites. This transcriptional activation by Spi-B and CBP was inhibited by expression of c-Myb, and the transcriptional activation by c-Myb and CBP was inhibited by expression of Spi-B, suggesting competition for CBP between these two transcription factors. Our results suggest that CBP acts as a transcriptional coactivator of Spi-B and mediates synergistic or antagonistic interactions between other transcription factors.
Mesh Terms:
Acetyltransferases, Animals, Blotting, Western, CREB-Binding Protein, DNA-Binding Proteins, Down-Regulation, Glutathione Transferase, Hematopoiesis, Humans, Luciferases, Mice, Nuclear Proteins, Peptides, Plasmids, Precipitin Tests, Protein Binding, Proto-Oncogene Proteins, Proto-Oncogene Proteins c-myb, Trans-Activators, Transcription Factors, Transcription, Genetic, Transcriptional Activation
Cell Growth Differ.
Date: Feb. 01, 2002
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