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.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
5R01DK065029-11
Application #
8685956
Study Section
Molecular and Cellular Hematology (MCH)
Program Officer
Bishop, Terry Rogers
Project Start
2003-07-01
Project End
2018-06-30
Budget Start
2014-07-01
Budget End
2015-06-30
Support Year
11
Fiscal Year
2014
Total Cost
Indirect Cost
Name
University of California Los Angeles
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
City
Los Angeles
State
CA
Country
United States
Zip Code
90095
Latour, Chloé; Wlodarczyk, Myriam F; Jung, Grace et al. (2017) Erythroferrone contributes to hepcidin repression in a mouse model of malarial anemia. Haematologica 102:60-68
Coffey, Richard; Ganz, Tomas (2017) Iron homeostasis: An anthropocentric perspective. J Biol Chem 292:12727-12734
Aschemeyer, Sharraya; Gabayan, Victoria; Ganz, Tomas et al. (2017) Erythroferrone and matriptase-2 independently regulate hepcidin expression. Am J Hematol 92:E61-E63
Ganz, Tomas; Jung, Grace; Naeim, Arash et al. (2017) Immunoassay for human serum erythroferrone. Blood 130:1243-1246
Ganz, Tomas; Nemeth, Elizabeta (2016) Iron Balance and the Role of Hepcidin in Chronic Kidney Disease. Semin Nephrol 36:87-93
Hanudel, Mark R; Chua, Kristine; Rappaport, Maxime et al. (2016) Effects of dietary iron intake and chronic kidney disease on fibroblast growth factor 23 metabolism in wild-type and hepcidin knockout mice. Am J Physiol Renal Physiol 311:F1369-F1377
Drakesmith, Hal; Nemeth, Elizabeta; Ganz, Tomas (2015) Ironing out Ferroportin. Cell Metab 22:777-87
Kautz, Léon; Jung, Grace; Du, Xin et al. (2015) Erythroferrone contributes to hepcidin suppression and iron overload in a mouse model of ?-thalassemia. Blood 126:2031-7
Kim, Airie; Nemeth, Elizabeta (2015) New insights into iron regulation and erythropoiesis. Curr Opin Hematol 22:199-205
Nemeth, Elizabeta; Ganz, Tomas (2014) Anemia of inflammation. Hematol Oncol Clin North Am 28:671-81, vi

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