Negative regulation of chicken GATA-1 promoter activity mediated by a hormone response element.

GATA-1 is a DNA-binding protein that regulates transcription of erythroid-specific genes and is required for the formation of mature erythroid cells. We show here that the GATA-1 hormone response-like element (GHRE) within the first intron of the gene functions as an inhibitory element in chicken erythroid precursor cells, as revealed by expression studies with mutants of the minimal GATA-1 promoter. We identify in these precursor cells the relevant proteins that interact with GHRE as a heterodimer of the thyroid hormone receptor alpha and the chicken ovalbumin upstream promoter transcription factor. Our results indicate that this novel complex can negatively regulate the GATA-1 promoter and suggest that GATA-1 can overcome this inhibitory action. We provide evidence that the viral gene product, v-erb A, can also reduce GATA-1 promoter activity through the GHRE site.