Article

Modulation of bone morphogenetic protein signaling in vivo regulates systemic iron balance.

Program in Membrane Biology and Nephrology Division, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA.
Journal of Clinical Investigation (Impact Factor: 13.77). 08/2007; 117(7):1933-9. DOI: 10.1172/JCI31342
Source: PubMed

ABSTRACT Systemic iron balance is regulated by hepcidin, a peptide hormone secreted by the liver. By decreasing cell surface expression of the iron exporter ferroportin, hepcidin decreases iron absorption from the intestine and iron release from reticuloendothelial stores. Hepcidin excess has been implicated in the pathogenesis of anemia of chronic disease, while hepcidin deficiency has a key role in the pathogenesis of the iron overload disorder hemochromatosis. We have recently shown that hemojuvelin is a coreceptor for bone morphogenetic protein (BMP) signaling and that BMP signaling positively regulates hepcidin expression in liver cells in vitro. Here we show that BMP-2 administration increases hepcidin expression and decreases serum iron levels in vivo. We also show that soluble hemojuvelin (HJV.Fc) selectively inhibits BMP induction of hepcidin expression in vitro and that administration of HJV.Fc decreases hepcidin expression, increases ferroportin expression, mobilizes splenic iron stores, and increases serum iron levels in vivo. These data support a role for modulators of the BMP signaling pathway in treating diseases of iron overload and anemia of chronic disease.

0 Followers
 · 
123 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: Iron, an essential nutrient, is required for many diverse biological processes. The absence of a defined pathway to excrete excess iron makes it essential for the body to regulate the amount of iron absorbed; a deficiency could lead to iron deficiency and an excess to iron overload, and associated disorders such as anemia and hemochromatosis, respectively. This regulation is mediated by the iron-regulatory hormone hepcidin. Hepcidin binds to the only known iron export protein, ferroportin, inducing its internalization and degradation, thus limiting the amount of iron released into the blood. The major factors that are implicated in hepcidin regulation include iron stores, hypoxia, inflammation and erythropoiesis. This review summarizes our present knowledge about the molecular mechanisms and signaling pathways contributing to hepcidin regulation by these factors.
    Bioscience Reports 03/2015; 35(3). DOI:10.1042/BSR20150014 · 2.85 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Iron is an essential component of erythropoiesis and its metabolism is tightly regulated by a variety of internal and external cues including iron storage, tissue hypoxia, inflammation and degree of erythropoiesis. There has been remarkable improvement in our understanding of the molecular mechanisms of iron metabolism past decades. The classical model of iron metabolism with iron response element/iron response protein (IRE/IRP) is now extended to include hepcidin model. Endogenous and exogenous signals funnel down to hepcidin via wide range of signaling pathways including Janus Kinase/Signal Transducer and Activator of Transcription 3 (JAK/STAT3), Bone Morphogenetic Protein/Hemojuvelin/Mothers Against Decapentaplegic Homolog (BMP/HJV/SMAD), and Von Hippel Lindau/Hypoxia-inducible factor/Erythropoietin (VHL/HIF/EPO), then relay to ferroportin, which directly regulates intra- and extracellular iron levels. The successful molecular delineation of iron metabolism further enhanced our understanding of common genetic and acquired disorder, hemochromatosis. The majority of the hereditary hemochromatosis (HH) patients are now shown to have mutations in the genes coding either upstream or downstream proteins of hepcidin, resulting in iron overload. The update on hepcidin centered mechanisms of iron metabolism and their clinical perspective in hemochromatosis will be discussed in this review. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.
    Critical Reviews in Oncology/Hematology 02/2015; DOI:10.1016/j.critrevonc.2015.02.006 · 4.05 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: In order to research how does hypomethylating agents ameliorate iron metabolism in myelodysplastic syndrome (MDS), we performed methylation-specific, polymerase chain reaction (MSP), bisulfate genomic sequencing polymerase chain reaction (BSP), quantitative real-time PCR and western blot of hemojuvelin (HJV) and ELISA assay for hepcidin before and after demethylating therapy (decitabine) to determine whether the change of HJV methylation status would have an influence on hepcidin expression. Eleven of 22 MDS patients achieved CR or PR according to IWG criteria (50%). HJV mRNA was induced in decitabine responders (p = .006 comparing pre/post decitabine treatment) but not in non-responders (p = .121). Similarly, hepcidin serum expression increased from 320.77 ± 34.8 μg/L to 366.77 ± 21.90 μg/L (p = .012) in responders but did not significantly change in non-responders (p = .058), while no difference of adjusted serum ferritin (ASF) was found. In conclusion, hypermethylation of HJV promoter region could silence the gene expression and demethylating therapy might ameliorate iron-overload through HJV demethylation.
    Cancer Investigation 02/2015; 39(4). DOI:10.3109/07357907.2014.1001895 · 2.06 Impact Factor

Preview

Download
4 Downloads
Available from