Inhibitory interaction of c-Myb and GATA-1 via transcriptional co-activator CBP.

Gene targeting experiments have revealed that transcription factors such as c-Myb and GATA-1 play crucial roles during hematopoietic differentiation. c-Myb is necessary in the immature cells of almost every hematopoietic lineage and GATA-1 is essential for the development of the erythroid lineage. In addition, CREB-binding protein (CBP) acts as a transcriptional adapter for various transcription factors, including c-Myb and GATA-1. In this paper, we show that the transcription factors c-Myb and GATA-1 each inhibit the transcriptional activity of the other and that any possible bipartite complexes c-Myb, GATA-1, and CBP could be formed, but the tripartite complex was hardly formed. The exclusive binding of GATA-1 and c-Myb to CBP is probably the molecular basis for the mutual inhibition of their transcriptional activity. Our data suggest that cross-talk between these three factors might be important for hematopoietic differentiation and that CBP functions as a key molecule during the process.