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 line age and GATA-1 is essential for the development of the ervthroid lineage. I n addition, CREB-binding protein (CBP) acts as a transcriptional adapter fo r various transcription factors, including c-Myc and GATA-1. In this paper, ,ve show that the transcription factors c-Myb and GATA-1 each inhibit the t ranscriptional activity of the other and that any possible bipartite comple xes 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 act ivity. Our data suggest that cross-talk between these three factors might b e important for hematopoietic differentiation and that CBP functions as a h ey molecule during the process.