Control of Systemic Iron Homeostasis by the 3' Iron-Responsive Element of Divalent Metal Transporter 1 in Mice.

Divalent metal transporter 1 (DMT1) is essential for dietary iron assimilation and erythroid iron acquisition. The 39 untranslated region of the murine DMT1 mRNA contains an iron responsive element (IRE) that is conserved in humans but whose functional role remains unclear. We generated and analyzed mice with targeted disruption of the DMT1 39IRE. These animals display hypoferremia during the suckling period, associated with a reduction of DMT1 mRNA and protein in the intestine. In contrast, adult mice exhibit hyperferremia, accompanied by enlargement of hepatic and splenic iron stores. Intriguingly, disruption of the DMT1 39IRE in adult animals augments intestinal DMT1 expression, in part due to increased mRNA translation. Hence, during postnatal growth, the DMT1 39IRE promotes intestinal DMT1 expression and secures iron sufficiency; in adulthood, it suppresses DMT1 and prevents systemic iron loading. This work demonstrates that the 39IRE of DMT1 plays a role in the control of DMT1 expression and systemic iron homeostasis, and reveals an age-dependent switch in its activity.