Regnase-1 Maintains Iron Homeostasis via the Degradation of Transferrin Receptor 1 and Prolyl-Hydroxylase-Domain-Containing Protein 3 mRNAs

Publication date: 23 May 2017
Source:Cell Reports, Volume 19, Issue 8
Author(s): Masanori Yoshinaga, Yoshinari Nakatsuka, Alexis Vandenbon, Daisuke Ori, Takuya Uehata, Tohru Tsujimura, Yutaka Suzuki, Takashi Mino, Osamu Takeuchi
Iron metabolism is regulated by transcriptional and post-transcriptional mechanisms. The mRNA of the iron-controlling gene, transferrin receptor 1 (TfR1), has long been believed to be negatively regulated by a yet-unidentified endonuclease. Here, we show that the endonuclease Regnase-1 is critical for the degradation of mRNAs involved in iron metabolism in vivo. First, we demonstrate that Regnase-1 promotes TfR1 mRNA decay. Next, we show that Regnase-1^−/− mice suffer from severe iron deficiency anemia, although hepcidin expression is downregulated. The iron deficiency anemia is induced by a defect in duodenal iron uptake. We reveal that duodenal Regnase-1 controls the expression of PHD3, which impairs duodenal iron uptake via HIF2α suppression. Finally, we show that Regnase-1 is a HIF2α-inducible gene and thus provides a positive feedback loop for HIF2α activation via PHD3. Collectively, these results demonstrate that Regnase-1-mediated regulation of iron-related transcripts is essential for the maintenance of iron homeostasis.

Graphical abstract

Teaser

Iron homeostasis is regulated by post-transcriptional mechanisms. Yoshinaga et al. demonstrate that an endoribonuclease, Regnase-1, destabilizes mRNAs related to iron metabolism, including TfR1 and PHD3. A positive feedback circuit of Regnase-1, PHD3, and HIF2α is critical for iron uptake in the duodenal epithelium and facilitates proper erythropoiesis.


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