ACTIVATION OF THE ERYTHROPOIETIN PROMOTER BY A POINT MUTATION FROM GATA TO TATA IN THE -30 REGION

We show here a role of the highly conserved GATA motif in the -30 regi on of the erythropoietin (Epo) promoter. Epo production is reduced in normoxia and activated in hypoxia to control the oxygen supply through erythropoiesis. Although the hypoxic inducibility has been analyzed, the molecular mechanism for the low basal activity in normoxia remaine d unclear. The GATA motif in the -30 region upstream of the transcript ion initiation site is highly conserved among the species. In many gen es, the consensus motif in the -30 region is TATA. The GATA motif of t he Epo promoter was mutated to TATA. The transcriptional activity of t he mutant was enhanced even in normoxia. Binding assays showed that TA TA-binding protein (TBP) could weakly bind to the wild-type GATA motif whereas TBP bound to the mutant TATA motif with high affinity. These results indicate that the highly conserved GATA motif in the -30 regio n of the Epo promoter can avoid binding and activation by TBP. This ev idence is considered to be the molecular basis for the low physiologic al expression from the Epo promoter in normoxia.