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 region 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 remained unclear. The GATA motif in the -30 region upstream of the transcription initiation site is highly conserved among the species. In many genes, the consensus motif in the -30 region is TATA. The GATA motif of the Epo promoter was mutated to TATA. The transcriptional activity of the mutant was enhanced even in normoxia. Binding assays showed that TATA-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 region of the Epo promoter can avoid binding and activation by TBP. This evidence is considered to be the molecular basis for the low physiological expression from the Epo promoter in normoxia.