Intestinal Hypoxia-inducible Factor-2α(HIF-2α) Is Critical for Efficient Erythropoiesis

Erythropoiesis is a coordinated process by which RBCs are produced. Erythropoietin, a kidney-derived hormone, and iron are critical for the production of oxygen-carrying mature RBCs. To meet the high demands of iron during erythropoiesis, small intestinal iron absorption is increased through an undefined mechanism. In this study, erythropoietic induction of iron absorption was further investigated. Hypoxia-inducible factor-2 alpha (HIF-2 alpha) signaling was activated in the small intestine during erythropoiesis. Genetic disruption of HIF-2 alpha in the intestine abolished the increase in iron absorption genes as assessed by quantitative real-time reverse transcription-PCR and Western blot analyses. Moreover, the increase in serum iron following induction of erythropoiesis was entirely dependent on intestinal HIF-2 alpha expression. Complete blood count analysis demonstrated that disruption of intestinal HIF-2 alpha inhibited efficient erythropoiesis; mice disrupted for HIF-2 alpha demonstrated lower hematocrit, RBCs, and Hb compared with wildtype mice. These data further cement the essential role of HIF-2 alpha in regulating iron absorption and also demonstrate that hypoxia sensing in the intestine, as well as in the kidney, is essential for regulation of erythropoiesis by HIF-2 alpha.