Hepatic hepcidin/intestinal HIF-2α axis maintains iron absorption during iron deficiency and overload
Andrew J. Schwartz, … , Justin A. Colacino, Yatrik M. Shah
Andrew J. Schwartz, … , Justin A. Colacino, Yatrik M. Shah
Published October 23, 2018
Citation Information: J Clin Invest. 2019;129(1):336-348. https://doi.org/10.1172/JCI122359.
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Research Article Gastroenterology

Hepatic hepcidin/intestinal HIF-2α axis maintains iron absorption during iron deficiency and overload

Abstract

Iron-related disorders are among the most prevalent diseases worldwide. Systemic iron homeostasis requires hepcidin, a liver-derived hormone that controls iron mobilization through its molecular target ferroportin (FPN), the only known mammalian iron exporter. This pathway is perturbed in diseases that cause iron overload. Additionally, intestinal HIF-2α is essential for the local absorptive response to systemic iron deficiency and iron overload. Our data demonstrate a hetero-tissue crosstalk mechanism, whereby hepatic hepcidin regulated intestinal HIF-2α in iron deficiency, anemia, and iron overload. We show that FPN controlled cell-autonomous iron efflux to stabilize and activate HIF-2α by regulating the activity of iron-dependent intestinal prolyl hydroxylase domain enzymes. Pharmacological blockade of HIF-2α using a clinically relevant and highly specific inhibitor successfully treated iron overload in a mouse model. These findings demonstrate a molecular link between hepatic hepcidin and intestinal HIF-2α that controls physiological iron uptake and drives iron hyperabsorption during iron overload.

Authors

Andrew J. Schwartz, Nupur K. Das, Sadeesh K. Ramakrishnan, Chesta Jain, Mladen T. Jurkovic, Jun Wu, Elizabeta Nemeth, Samira Lakhal-Littleton, Justin A. Colacino, Yatrik M. Shah

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Figure 6

FPN activates HIF-2α in a cell-autonomous manner that is dependent on efflux of the cellular labile iron pool.

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FPN activates HIF-2α in a cell-autonomous manner that is dependent on ef...
(A) Western blot analysis of FPNGFP HEK293 cells following a 24-hour doxycycline treatment. (B) Western blot analysis of cytosolic and nuclear fractions of FPNGFP HEK293 cells treated with vehicle (V), 250 ng/ml doxycycline (D), or 100 μM FG4592 (FG) for 24 hours. (C and D) Western blot analysis of cytosolic and nuclear fractions of FPNGFP HEK293 cells treated with vehicle (V), doxycycline (D), doxycycline and 200 μM FAC (D+F), or doxycycline and 1 mg/ml hepcidin (D+H) for 24 hours (C). Separate doxycycline plus FAC and doxycycline plus hepcidin conditions were also cotreated with FG4592 for 24 hours, as indicated (D). (E) Schematic of the luciferase-based PHD enzyme activity reporter. (F) Fold change of luciferase activity in FPNGFP HEK293 cells infected with the PHD reporter and treated with vehicle, doxycycline, FG4592, FAC and doxycycline, or doxycycline and hepcidin for 24 hours. (G) Western blot analysis of FPNGFP HEK293 cells stable for empty lentiCRISPRv2 (Empty) or unique NCOA4 short guide RNAs (NCOA4 sg1 and NCOA4 sg2). Cells were treated with FAC for 24 hours and then with doxycycline for 24 hours. (H) Western blot analysis of FPNGFP IEC-6 cells treated with vehicle, doxycycline, or doxycycline and hepcidin for 24 hours. (I) ELISA of lysates from FPNGFP IEC-6 cells treated with vehicle, doxycycline, doxycycline and hepcidin, or DFO for 24 hours. (J) Fold change of luciferase activity in FPNGFP IEC-6 cells infected with the PHD reporter and treated with vehicle, doxycycline, FAC and doxycycline, or doxycycline and hepcidin for 24 hours. All cell culture experiments were repeated at least 3 times. Data represent the mean ± SEM. Statistical significance was determined by 1-way ANOVA with Tukey’s post hoc test. **P < 0.01 and ****P < 0.0001 versus vehicle; #P < 0.05, ##P < 0.01, and ####P < 0.0001 versus doxycycline.