A Ferroportin Transcript that Lacks an Iron-Responsive Element Enables Duodenal and Erythroid Precursor Cells to Evade Translational Repression

作者：Zhang De Liang; Hughes Robert Im; Ollivierre Wilson Hayden; Ghosh Manik C; Rouault Tracey A^*

来源：Cell Metabolism, 2009, 9(5): 461-473.

DOI：10.1016/j.cmet.2009.03.006

Ferroportin (FPN1), the sole characterized mammalian iron exporter, has an iron-responsive element (IRE) in its 5' untranslated region, which ensures that its translation is repressed by iron regulatory proteins (IRPs) in iron-deficient conditions to maintain cellular iron content. However, here we demonstrate that duodenal epithelial and erythroid precursor cells utilize an alternative upstream promoter to express a FPN1 transcript, FPN1 13, which lacks the IRE and is not repressed in iron-deficient conditions. The FPN1 B transcript encodes ferroportin with an identical open reading frame and contributes significantly to ferroportin protein expression in erythroid precursors and likely also in the duodenum of iron-starved animals. The identification of FPN1B reveals how FPN1 expression can bypass IRP-dependent repression in intestinal iron uptake, even when cells throughout the body are iron deficient. In erythroid precursor cells, we hypothesize that FPN1 B expression enhances real-time sensing of systemic iron status and facilitates restriction of erythropoiesis in response to low systemic iron.

• 出版日期2009-5-6