Abstract
Hypoxia stimulates erythropoiesis, the major iron-utilization pathway. We report the discovery of a conserved, functional iron-responsive element (IRE) in the 5′ untranslated region of the messenger RNA encoding endothelial PAS domain protein-1, EPAS1 (also called hypoxia-inducible factor-2α, HIF2α). Via this IRE, iron regulatory protein binding controls EPAS1 mRNA translation in response to cellular iron availability. Our results uncover a regulatory link that permits feedback control between iron availability and the expression of a key transcription factor promoting iron utilization. They also show that an IRE that is structurally distinct from, for example, the ferritin mRNA IRE and that has been missed by in silico approaches, can mediate mechanistically similar responses.
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Acknowledgements
We thank Y. Vainshtein for support with microarray data analysis, J. Stolte for maintenance of the IronChip platform, V. Benes and members of the European Molecular Biology Laboratory Genomics Core Facility for help with qPCR and sequencing, and D. Shouval (Hadassah University Hospital) for kindly providing the RC1 renal carcinoma cell line. This work was supported by grants from the Marie Curie Quality of Life Programme, CORDIS FP5 (QLGA-CT-2001-52011) and the Young Investigator Award of the Medical Faculty, University of Heidelberg to M.S., by grants from the Forschungsschwerpunktprogramm des Landes Baden-Württemberg (RNA and disease) to M.U.M. and M.W.H. and by funds from the Gottfried Wilhem Leibniz Prize to M.W.H.
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M.S., B.G., M.U.M. and M.W.H designed and analyzed the experiments and wrote the paper. M.S. and B.G. performed the experiments.
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Supplementary information
Supplementary Fig. 1
Phylogenetic conservation of the EPAS1 5′ untranslated region iron-responsive element. (PDF 341 kb)
Supplementary Fig. 2
Iron regulation of the EPAS1 iron-responsive element in HeLa cells. (PDF 323 kb)
Supplementary Fig. 3
EPAS1 and HIF1α expression in RC1. (PDF 1478 kb)
Supplementary Table 1
Oligonucleotides used in this study. (PDF 21 kb)
Supplementary Methods
5′ rapid amplification of cDNA ends. (PDF 16 kb)
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Sanchez, M., Galy, B., Muckenthaler, M. et al. Iron-regulatory proteins limit hypoxia-inducible factor-2α expression in iron deficiency. Nat Struct Mol Biol 14, 420–426 (2007). https://doi.org/10.1038/nsmb1222
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DOI: https://doi.org/10.1038/nsmb1222
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