NEGATIVE REGULATION OF CHICKEN GATA-1 PROMOTER ACTIVITY MEDIATED BY AHORMONE RESPONSE ELEMENT

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