GATA Motif on the Erythropoietin Gene Promoter Is Essential for Repression of Ectopic Constitutive Erythropoietin Production.

Abstract

In response to anemia erythropoietin ( Epo) gene transcription is markedly induced in the kidney and liver. This regulation has been ascribed for the promoter GATA motif and 3′ enhancer. To elucidate how the Epo gene expression is regulated in vivo, we established transgenic mouse lines expressing green fluorescent protein (GFP) under the control of 180-kb mouse Epo gene locus. GFP expression was induced by anemia or hypoxia specifically in peritubular interstitial cells of renal cortex and hepatocytes surrounding the central vein. Surprisingly, the renal Epo-producing cells were identified with neuron-like morphology and expression of neuronal markers. We also examined the regulatory mechanism of Epo gene using the transgenes in which mutations had been introduced in the GATA promoter motif, since we have reported the motif as a negative regulatory element for the inducible Epo gene expression. A single nucleotide mutation in the motif resulted in constitutive ectopic expression of GFP in the renal distal tubules, collecting ducts and certain epithelial cells of other tissues. Since both GATA-2 and GATA-3 bind to the GATA box in the distal tubular cells, these factors are likely to constitutively repress ectopic Epo gene expression in these cells. Thus, GATA-based repression is essential for the inducible and cell-type specific expression of the Epo gene.