scholarly journals Angiocrine Bmp2 signaling in murine liver controls normal iron homeostasis

Blood ◽  
2017 ◽  
Vol 129 (4) ◽  
pp. 415-419 ◽  
Author(s):  
Philipp-Sebastian Koch ◽  
Victor Olsavszky ◽  
Friederike Ulbrich ◽  
Carsten Sticht ◽  
Alexandra Demory ◽  
...  

Key Points Angiocrine Bmp2 signaling in the liver controls tissue and serum iron concentrations via regulation of hepcidin expression in hepatocytes. Liver-specific angiocrine signaling is essential for the metabolic homeostasis of the whole organism.

Drug Research ◽  
2021 ◽  
Author(s):  
Vishal Patel ◽  
Amit Joharapurkar ◽  
Samadhan Kshirsagar ◽  
Maulik Patel ◽  
Hiren Patel ◽  
...  

Abstract Background Hepcidin, a liver-derived peptide, regulates the absorption, distribution, and circulation of iron in the body. Inflammation or iron overload stimulates hepcidin release, which causes the accumulation of iron in tissues. The inadequate levels of iron in circulation impair erythropoiesis. Inhibition of hepcidin may increase iron in circulation and improve efficient erythropoiesis. Activin-like kinase (ALK) inhibitors decrease hepcidin. Methods In this work, we have investigated an ALK inhibitor LDN193189 for its efficacy in iron homeostasis. The effect of LDN193189 treatment was assessed in C57BL6/J mice, in which hepcidin was induced by either ferrous sulfate or lipopolysaccharide (LPS) injection. Results After two hours of treatment, ferrous sulfate increased serum and liver iron, serum hepcidin, and liver hepcidin expression. On the other hand, LPS reduced serum iron in a dose-related manner after six hours of treatment. LDN193189 treatment increased serum iron, decreased spleen and liver iron, decreased serum hepcidin and liver hepcidin expression in ferrous sulfate-treated mice, and increased serum iron in LPS-induced hypoferremia. We observed that ferrous sulfate caused a significantly higher increase in liver iron, serum hepcidin, and liver hepcidin than turpentine oil or LPS in mice. Iron dextran (intraperitoneal or intravenous) increased serum iron, but LDN193189 did not show hyperferremia with iron dextran stimulus. Conclusion Ferrous sulfate-induced hyperferremia can be a valuable and rapid screening model for assessing the efficacy of hepcidin inhibitors.


Blood ◽  
2009 ◽  
Vol 114 (9) ◽  
pp. 1913-1918 ◽  
Author(s):  
Curry L. Koening ◽  
Jennifer C. Miller ◽  
Jenifer M. Nelson ◽  
Diane M. Ward ◽  
James P. Kushner ◽  
...  

Hepcidin is the major regulator of systemic iron homeostasis in mammals. Hepcidin is produced mainly by the liver and is increased by inflammation, leading to hypoferremia. We measured serum levels of bioactive hepcidin and its effects on serum iron levels in mice infected with Borrelia burgdorferi. Bioactive hepcidin was elevated in the serum of mice resulting in hypoferremia. Infected mice produced hepcidin in both liver and spleen. Both intact and sonicated B burgdorferi induced hepcidin expression in cultured mouse bone marrrow macrophages. Hepcidin production by cultured macrophages represents a primary transcriptional response stimulated by B burgdorferi and not a secondary consequence of cytokine elaboration. Hepcidin expression induced by B burgdorferi was mediated primarily by activation of Toll-like receptor 2.


Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. SCI-25-SCI-25
Author(s):  
Jodie L. Babitt

Abstract Abstract SCI-25 Systemic iron balance is regulated by the key iron regulatory hormone hepcidin. Secreted by the liver, hepcidin inhibits iron absorption from the diet and iron mobilization from body stores by decreasing cell surface expression of the iron export protein ferroportin. Iron administration increases hepcidin expression, thereby providing a feedback mechanism to limit further iron absorption, while anemia and hypoxia inhibit hepcidin expression, thereby increasing iron availability for erythropoiesis. Hepcidin excess is thought to have a role in the anemia of inflammation, while hepcidin deficiency is thought to be the common pathogenic mechanism underlying the iron overload disorder hereditary hemochromatosis, due to mutations in the genes encoding hepcidin itself (HAMP), HFE, transferrin receptor 2 (TFR2), or hemojuvelin (HFE2). Notably the precise molecular mechanisms by which iron levels are “sensed” and how this iron “signal” is transduced to modulate hepcidin expression have remained elusive. We have recently discovered that hemojuvelin is a co-receptor for the bone morphogenetic protein (BMP) signaling pathway, and that hemojuvelin-mediated BMP signals increase hepcidin expression at the transcriptional level. In addition to patients with HFE2 mutations and Hfe2 knockout mice, other genetic mouse models associated with impaired hepatic BMP signaling through a global knockout of the ligand Bmp6, or selective hepatic knockout of an intracellular mediator of BMP signaling, Smad4, also cause inappropriately low hepcidin expression and iron overload. Exogenous BMP6 administration in mice increases hepatic hepcidin expression and reduces serum iron, while BMP6 antagonists inhibit hepatic hepcidin expression, mobilize reticuloendothelial cell iron stores and increase serum iron. Not only does the BMP6-hemojuvelin-SMAD pathway regulate hepcidin expression and thereby systemic iron homeostasis, but also the BMP6-SMAD pathway itself is regulated by iron. Acute iron administration in mice increases phosphorylation of Smad proteins in the liver, and chronic changes in dietary iron modulate hepatic Bmp6 mRNA expression and phosphorylation of Smad proteins concordantly with Hamp mRNA expression. Together, these data support the paramount role of the BMP6-hemojuvelin-SMAD signaling pathway in the iron-mediated regulation of hepcidin expression and systemic iron homeostasis, and suggest that modulators of this pathway may be an alternative therapeutic strategy for treating disorders of iron homeostasis. Recent work elucidating the role of the BMP signaling pathway in hepcidin regulation and systemic iron homeostasis will be presented. Disclosures Babitt: Ferrumax Pharmaceuticals, Inc.: Equity Ownership.


Blood ◽  
2021 ◽  
Author(s):  
Caroline A. Enns ◽  
Shall Jue ◽  
An-Sheng Zhang

Neogenin (NEO1) is a ubiquitously expressed multi-functional transmembrane protein. It interacts with hemojuvelin (HJV), a BMP co-receptor that plays a pivotal role in hepatic hepcidin expression. Earlier studies suggest that the function of HJV relies on its interaction with NEO1. However, the role of NEO1 in iron homeostasis remains controversial because of the lack of an appropriate animal model. Here, we generated a hepatocyte-specific Neo1 knockout (Neo1fl/fl;Alb-Cre+) mouse model that circumvented the developmental and lethality issues of the global Neo1 mutant. Results show that ablation of hepatocyte Neo1 decreased hepcidin expression and caused iron overload. This iron overload did not result from altered iron utilization by erythropoiesis. Replacement studies revealed that expression of the Neo1L1046E mutant that does not interact with Hjv, was unable to correct the decreased hepcidin expression and high serum iron in Neo1fl/fl;Alb-Cre+ mice. In Hjv-/- mice, expression of HjvA183R mutant that has reduced interaction with Neo1, also displayed a blunted induction of hepcidin expression. These observations indicate that Neo1-Hjv interaction is essential for hepcidin expression. Further analyses suggest that the Hjv binding triggered the cleavage of the Neo1 cytoplasmic domain by a protease, which resulted in accumulation of truncated Neo1 on the plasma membrane. Additional studies did not support that Neo1 functions by inhibiting Hjv shedding as previously proposed. Together, our data favor a model in which Neo1 interaction with Hjv leads to accumulation of cleaved Neo1 on the plasma membrane, where Neo1 acts as a scaffold to induce the Bmp signaling and hepcidin expression.


Blood ◽  
2011 ◽  
Vol 117 (3) ◽  
pp. 997-1004 ◽  
Author(s):  
Maura Poli ◽  
Domenico Girelli ◽  
Natascia Campostrini ◽  
Federica Maccarinelli ◽  
Dario Finazzi ◽  
...  

Abstract Hepcidin is a major regulator of iron homeostasis, and its expression in liver is regulated by iron, inflammation, and erythropoietic activity with mechanisms that involve bone morphogenetic proteins (BMPs) binding their receptors and coreceptors. Here we show that exogenous heparin strongly inhibited hepcidin expression in hepatic HepG2 cells at pharmacologic concentrations, with a mechanism that probably involves bone morphogenetic protein 6 sequestering and the blocking of SMAD signaling. Treatment of mice with pharmacologic doses of heparin inhibited liver hepcidin mRNA expression and SMAD phosphorylation, reduced spleen iron concentration, and increased serum iron. Moreover, we observed a strong reduction of serum hepcidin in 5 patients treated with heparin to prevent deep vein thrombosis, which was accompanied by an increase of serum iron and a reduction of C-reactive protein levels. The data show an unrecognized role for heparin in regulating iron homeostasis and indicate novel approaches to the treatment of iron-restricted iron deficiency anemia.


2011 ◽  
Vol 49 (01) ◽  
Author(s):  
S Arndt ◽  
U Mägdefrau ◽  
C Dorn ◽  
K Schardt ◽  
C Hellerbrand ◽  
...  

Blood ◽  
2014 ◽  
Vol 123 (23) ◽  
pp. 3646-3650 ◽  
Author(s):  
Sara Zumerle ◽  
Jacques R. R. Mathieu ◽  
Stéphanie Delga ◽  
Mylène Heinis ◽  
Lydie Viatte ◽  
...  

Key Points Liver-specific hepcidin KO mice fully recapitulate the severe iron overload phenotype observed in the total KO mice. The hepcidin produced by hepatocytes is the main regulator of body iron homeostasis.


Author(s):  
Eric P. Skaar ◽  
Roger Echols ◽  
Yuko Matsunaga ◽  
Anju Menon ◽  
Simon Portsmouth

AbstractCritically ill patients often present with low serum iron levels or anemia. We evaluated the impact of iron levels and iron homeostasis on the efficacy and safety of cefiderocol, an iron-chelator siderophore cephalosporin, in patients with nosocomial pneumonia in a post hoc analysis of the randomized, double-blind, Phase 3 APEKS-NP study (NCT03032380). Patients with Gram-negative nosocomial pneumonia received cefiderocol 2 g, 3-h infusion, q8h, or high-dose, extended-infusion meropenem 2 g, 3-h infusion, q8h, for 7–14 days. Efficacy and safety parameters, including specific iron homeostasis parameters (i.e., hepcidin, iron, total iron binding capacity, transferrin saturation), were analyzed according to baseline iron levels. In the cefiderocol and meropenem arms, 79.1% (117/148) and 83.3% (125/150) randomized patients, respectively, had low baseline serum iron levels. Rates of 14-day (12.3% [14/114] vs 11.6% [14/121]) and 28-day all-cause mortality (20.5% [23/112] vs 19.0% [23/121]), clinical cure (63.2% [72/114] vs 67.2% [82/122]), and microbiological eradication (43.6% [41/94] vs 48.1% [51/106]) at test of cure were similar in cefiderocol vs meropenem arms, respectively. In the overall safety population, rates of anemia-related adverse events were similar (cefiderocol arm 18.2% [27/148], meropenem arm 18.7% [28/150]). Changes from baseline to test of cure in hepcidin, iron, total iron binding capacity, and transferrin saturation were similar between treatment arms. Cefiderocol treatment did not affect iron homeostasis, and its efficacy and safety were not influenced by baseline serum iron levels. Clinicaltrials.gov registration: NCT03032380. Date of registration: 26 January 2017.


2008 ◽  
Vol 86 (7) ◽  
pp. 825-835 ◽  
Author(s):  
Milan Theurl ◽  
Igor Theurl ◽  
Kathrin Hochegger ◽  
Peter Obrist ◽  
Nathan Subramaniam ◽  
...  

Blood ◽  
2017 ◽  
Vol 129 (4) ◽  
pp. 405-414 ◽  
Author(s):  
Susanna Canali ◽  
Kimberly B. Zumbrennen-Bullough ◽  
Amanda B. Core ◽  
Chia-Yu Wang ◽  
Manfred Nairz ◽  
...  

Key Points Endothelial Bmp6 conditional knockout mice exhibit hemochromatosis, whereas hepatocyte and macrophage Bmp6 conditional knockout mice do not. Our data support a model in which EC Bmp6 has paracrine actions on hepatocyte hemojuvelin to regulate hepcidin production.


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