Duodenal cytochrome b (Cybrd 1) and HIF-2α expression during acute hypoxic exposure in mice.

Background: Recent evidence suggests that the duodenum can regulate iron absorption independently of hepcidin via the transcription factor Hif-2α acting directly on the transcription of the proteins involved in the iron transport. The current study investigates the temporal relationship between Dcytb and Hif-2α during early hypoxic stimulus in the enterocyte in vivo. Methods: Duodenal Dcytb and Hif-2α protein expression was analysed by Western blot technique while gene regulation was determined by quantitative PCR. Results: Both Dcytb and Hif-2α protein expression were increased during the first hours of hypoxic duration. A change in hepcidin expression however, was significant only at 72 h hypoxia. Increased iron absorption reported in early hypoxia could be accounted for in part by the enhancement of Dcytb expression by Hif-2α in the duodenum. Conclusion: Modulation of Hif-2α predominates over hepcidin in the regulation of intestinal iron absorption during short hypoxic duration. The intestine exerts regulatory mechanisms in the dietary absorption of iron into systemic circulation. [ABSTRACT FROM AUTHOR]