Reactivation of hepatic EPO synthesis in mice after PHD loss.

The kidney controls erythropoietin production in adults, and the anemia that can accompany renal failure is a major medical problem. The liver controls erythropoietin production during fetal life but is silenced shortly after birth. Erythropoietin transcription is controlled by hypoxia-inducible factor (HIF), which is inhibited by three prolyl hydroxylases (PHD1, PHD2, and PHD3). Systemic PHD2 inactivation has been found to increase renal, but not hepatic, erythropoietin production. In contrast, we show here that simultaneous genetic inactivation of all three PHD paralogs in mice reactivates hepatic erythropoietin production and stimulates red blood synthesis, suggesting that pan-PHD inhibitory drugs might be useful for the treatment of anemia caused by chronic kidney disease.