The production of erythrocytes depends on the timely delivery of sufficient iron to erythroid precursors. The iron supply to the marrow comes under particular strain after hemorrhage, hemolysis, and other events that trigger expanded erythropoiesis. Both the absorption of dietary iron and the release of iron from stores are increased as erythropoiesis intensifies, but the mechanisms involved are not known, despite 50 years of research in this area. This competitive renewal application proposes and analyzes the mechanism by which erythropoietic activity influences iron homeostasis. Studies by our lab and others indicate that hepcidin is suppressed by factor(s) secreted by the bone marrow in response to erythropoietic stimulation, which then act on the liver. We therefore, initiated an unbiased search for a potential erythroid suppressor of hepcidin in the mouse by examining the time course of bone marrow gene expression after hemorrhage. We identified less than a dozen erythroid-specific transcripts whose expression changes prior to the suppression of hepcidin mRNA in the liver. Only one of them encoded a secreted protein, and this previously anonymous transcript (systematically named Fam132b and bearing resemblance to the TNF superfamily) was highly induced prior to hepcidin suppression. We have started analyzing the role of this transcript and the secreted protein using knockout mice, and have provisionally named it erythroferrone-1, as our preliminary data suggest it functions as a hormone linking erythropoiesis and iron metabolism.
The specific aims of the proposed project are: 1. Define the role of erythroferrone-1 in erythron-dependent regulation of iron metabolism 2. Characterize the erythroferrone-1 protein and establish its mechanism of action 3. Determine the role of erythroferrone-1 in the pathogenesis of iron overload in ?-thalassemia Successful completion of the proposed studies would answer longstanding questions about a fundamental aspect of human and vertebrate biology. It may also provide a lead therapeutic candidate (a biologically-based hepcidin suppressor) for the treatment of diseases of hepcidin excess such as anemia of inflammation or iron-refractory iron deficiency anemia (IRIDA). If the same or related factors also cause the suppression of hepcidin in ?-thalassemia and other iron-loading anemias, the work will provide important insights into the pathogenesis of iron overload in these globally common diseases. Pharmacologic antagonists of newly identified suppressors of hepcidin could offer new treatments to control the lethal iron overload in ?-thalassemia and other iron-loading anemias.

Public Health Relevance

We discovered a bone marrow-derived hormone that regulates the supply of iron to the marrow. Although the hormone may aid the recovery of red blood cells after blood loss, in Cooley's anemia the excess of this hormone could cause fatal iron overload. Understanding how this hormone works could improve the treatment of this disease.

National Institute of Health (NIH)
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Research Project (R01)
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Molecular and Cellular Hematology (MCH)
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Bishop, Terry Rogers
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University of California Los Angeles
Internal Medicine/Medicine
Schools of Medicine
Los Angeles
United States
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Kautz, Léon; Jung, Grace; Valore, Erika V et al. (2014) Identification of erythroferrone as an erythroid regulator of iron metabolism. Nat Genet 46:678-84
Kautz, Léon; Jung, Grace; Nemeth, Elizabeta et al. (2014) Erythroferrone contributes to recovery from anemia of inflammation. Blood 124:2569-74
Nemeth, Elizabeta; Ganz, Tomas (2014) Anemia of inflammation. Hematol Oncol Clin North Am 28:671-81, vi
Goodnough, Julia B; Ramos, Emilio; Nemeth, Elizabeta et al. (2012) Inhibition of hepcidin transcription by growth factors. Hepatology 56:291-9
Ganz, Tomas (2012) Macrophages and Systemic Iron Homeostasis. J Innate Immun :
Preza, Gloria C; Ruchala, Piotr; Pinon, Rogelio et al. (2011) Minihepcidins are rationally designed small peptides that mimic hepcidin activity in mice and may be useful for the treatment of iron overload. J Clin Invest 121:4880-8
Clark, Richard J; Tan, Chia Chia; Preza, Gloria C et al. (2011) Understanding the structure/activity relationships of the iron regulatory peptide hepcidin. Chem Biol 18:336-43
Ramos, Emilio; Kautz, Leon; Rodriguez, Richard et al. (2011) Evidence for distinct pathways of hepcidin regulation by acute and chronic iron loading in mice. Hepatology 53:1333-41
Maes, Ken; Nemeth, Elizabeta; Roodman, G David et al. (2010) In anemia of multiple myeloma, hepcidin is induced by increased bone morphogenetic protein 2. Blood 116:3635-44
Ganz, Tomas; Nemeth, Elizabeta (2009) Iron sequestration and anemia of inflammation. Semin Hematol 46:387-93

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