Effect of hepcidin on intestinal iron absorption in mice

Blood ◽  
2004 ◽  
Vol 103 (10) ◽  
pp. 3940-3944 ◽  
Author(s):  
Abas H. Laftah ◽  
Bala Ramesh ◽  
Robert J. Simpson ◽  
Nita Solanky ◽  
Seiamak Bahram ◽  
...  
Keyword(s):  
Iron Uptake ◽  
Iron Absorption ◽  
Iron Status ◽  
Hfe Gene ◽  
Chain Reaction ◽  
Liver Iron ◽  
Hepcidin Expression ◽  
Iron Deficient ◽  
Polymerase Chain

Abstract The effect of the putative iron regulatory peptide hepcidin on iron absorption was investigated in mice. Hepcidin peptide was synthesized and injected into mice for up to 3 days, and in vivo iron absorption was measured with tied-off segments of duodenum. Liver hepcidin expression was measured by reverse transcriptase–polymerase chain reaction. Hepcidin significantly reduced mucosal iron uptake and transfer to the carcass at doses of at least 10 μg/mouse per day, the reduction in transfer to the carcass being proportional to the reduction in iron uptake. Synthetic hepcidin injections down-regulated endogenous liver hepcidin expression excluding the possibility that synthetic hepcidin was functioning by a secondary induction of endogenous hepcidin. The effect of hepcidin was significant at least 24 hours after injection of hepcidin. Liver iron stores and hemoglobin levels were unaffected by hepcidin injection. Similar effects of hepcidin on iron absorption were seen in iron-deficient and Hfe knockout mice. Hepcidin inhibited the uptake step of duodenal iron absorption but did not affect the proportion of iron transferred to the circulation. The effect was independent of iron status of mice and did not require Hfe gene product. The data support a key role for hepcidin in the regulation of intestinal iron uptake.

scholarly journals CBIO-10. REDUCED IRON EXPORT FUNCTIONS IN A CELL INTRINSIC MANNER TO DRIVE GLIOBLASTOMA GROWTH

2020 ◽  
Vol 22 (Supplement_2) ◽  
pp. ii17-ii17
Author(s):  
Katie Troike ◽  
Erin Mulkearns-Hubert ◽  
Daniel Silver ◽  
James Connor ◽  
Justin Lathia
Keyword(s):  
Tumor Cells ◽  
Iron Uptake ◽  
Iron Homeostasis ◽  
Iron Status ◽  
Tumor Grade ◽  
Hfe Gene ◽  
Iron Release ◽  
Female Patients ◽  
Cellular Iron

Abstract Glioblastoma (GBM), the most common primary malignant brain tumor in adults, is characterized by invasive growth and poor prognosis. Iron is a critical regulator of many cellular processes, and GBM tumor cells have been shown to modulate expression of iron-associated proteins to enhance iron uptake from the surrounding microenvironment, driving tumor initiation and growth. While iron uptake has been the central focus of previous investigations, additional mechanisms of iron regulation, such as compensatory iron efflux, have not been explored in the context of GBM. The hemochromatosis (HFE) gene encodes a transmembrane glycoprotein that aids in iron homeostasis by limiting cellular iron release, resulting in a sequestration phenotype. We find that HFE is upregulated in GBM tumors compared to non-tumor brain and that expression of HFE increases with tumor grade. Furthermore, HFE mRNA expression is associated with significantly reduced survival specifically in female patients with GBM. Based on these findings, we hypothesize that GBM tumor cells upregulate HFE expression to augment cellular iron loading and drive proliferation, ultimately leading to reduced survival of female patients. To test this hypothesis, we generated Hfe knockdown and overexpressing mouse glioma cell lines. We observed significant alterations in the expression of several iron handling genes with Hfe knockdown or overexpression, suggesting global disruption of iron homeostasis. Additionally, we show that knockdown of Hfe in these cells increases apoptosis and leads to a significant impairment of tumor growth in vivo. These findings support the hypothesis that Hfe is a critical regulator of cellular iron status and contributes to tumor aggression. Future work will include further exploration of the mechanisms that contribute to these phenotypes as well as interactions with the tumor microenvironment. Elucidating the mechanisms by which iron effulx contributes to GBM may inform the development of next-generation targeted therapies.

Defective iron uptake by the duodenum of Belgrade rats fed diets of different iron contents

1996 ◽  
Vol 270 (5) ◽  
pp. G826-G832 ◽  
Author(s):  
P. S. Oates ◽  
E. H. Morgan
Keyword(s):  
Iron Content ◽  
Iron Uptake ◽  
Iron Transport ◽  
Iron Absorption ◽  
Microcytic Anemia ◽  
Deficient Diet ◽  
Hypochromic Microcytic Anemia ◽  
Iron Deficient

Homozygous Belgrade rats have an inherited hypochromic, microcytic anemia that is due to impaired iron transport into immature erythrocytes. There is also evidence for abnormal iron transport in other tissues such as the intestine. This study was aimed at investigating the intestinal defect in rats that had been fed diets for 12 days that are normal, low, or high in iron. The duodenal uptake, transfer, and absorption of Fe(III)-nitrilotriacetate and Fe(II)-ascorbate were studied using in vivo tied-off gut sacs in genetically normal rats and in heterozygous or homozygous Belgrade rats. In normal and heterozygous Belgrade rats, the handling of Fe(III) and Fe(II) was similar; uptake, transfer, and absorption of Fe(III) and Fe(II) changed inversely with the iron content of the diet. In contrast, in homozygous Belgrade rats the uptake of both Fe(III) and Fe(II) was markedly reduced and absorption of Fe(III) did not change when animals were fed an iron-deficient diet. Since absorption of Fe(II) was similar to Fe(III), there is no evidence that the defect in iron absorption is due to failure of a mechanism for reduction of Fe(III). The lowered uptake of Fe(III) and Fe(II) in homozygous Belgrade rats probably involves a defective iron carrier associated with the microvillous membrane of the duodenum.

scholarly journals Olfactory ferric and ferrous iron absorption in iron-deficient rats

2012 ◽  
Vol 302 (12) ◽  
pp. L1280-L1286 ◽  
Author(s):  
V. M. Ruvin Kumara ◽  
Marianne Wessling-Resnick
Keyword(s):  
Nasal Cavity ◽  
Ferrous Iron ◽  
Iron Uptake ◽  
Ferric Iron ◽  
Iron Absorption ◽  
Iron Status ◽  
Occupational Exposures ◽  
Divalent Metal Transporter 1 ◽  
Divalent Metal Transporter ◽  
Iron Deficient

The absorption of metals from the nasal cavity to the blood and the brain initiates an important route of occupational exposures leading to health risks. Divalent metal transporter-1 (DMT1) plays a significant role in the absorption of intranasally instilled manganese, but whether iron uptake would be mediated by the same pathway is unknown. In iron-deficient rats, blood 59Fe levels after intranasal administration of the radioisotope in the ferrous form were significantly higher than those observed for iron-sufficient control rats. Similar results were obtained when ferric iron was instilled intranasally, and blood levels of 59Fe were even greater in the iron-deficient rats compared with the amount of ferrous iron absorbed. Experiments with Belgrade ( b/b) rats showed that DMT1 deficiency limited ferric iron uptake from the nasal cavity to the blood compared with +/b controls matched for iron deficiency. These results indicate that olfactory uptake of ferric iron by iron-deficient rats involves DMT1. Western blot experiments confirmed that DMT1 levels are significantly higher in iron-deficient rats compared with iron-sufficient controls in olfactory tissue. Thus the molecular mechanism of olfactory iron absorption is regulated by body iron status and involves DMT1.

scholarly journals Contribution of Hfe expression in macrophages to the regulation of hepatic hepcidin levels and iron loading

Blood ◽  
2005 ◽  
Vol 106 (6) ◽  
pp. 2189-2195 ◽  
Author(s):  
Hortence Makui ◽  
Ricardo J. Soares ◽  
Wenlei Jiang ◽  
Marco Constante ◽  
Manuela M. Santos
Keyword(s):  
Bone Marrow ◽  
Iron Absorption ◽  
Hereditary Hemochromatosis ◽  
Peptide Hormone ◽  
Hfe Gene ◽  
Mrna Levels ◽  
Iron Loading ◽  
Liver Iron ◽  
Hepcidin Expression ◽  
Hepcidin Mrna

Abstract Hereditary hemochromatosis (HH), an iron overload disease associated with mutations in the HFE gene, is characterized by increased intestinal iron absorption and consequent deposition of excess iron, primarily in the liver. Patients with HH and Hfe-deficient (Hfe-/-) mice manifest inappropriate expression of the iron absorption regulator hepcidin, a peptide hormone produced by the liver in response to iron loading. In this study, we investigated the contribution of Hfe expression in macrophages to the regulation of liver hepcidin levels and iron loading. We used bone marrow transplantation to generate wild-type (wt) and Hfe-/- mice chimeric for macrophage Hfe gene expression. Reconstitution of Hfe-deficient mice with wt bone marrow resulted in augmented capacity of the spleen to store iron and in significantly decreased liver iron loading, accompanied by a significant increase of hepatic hepcidin mRNA levels. Conversely, wt mice reconstituted with Hfe-deficient bone marrow had a diminished capacity to store iron in the spleen but no significant alterations of liver iron stores or hepcidin mRNA levels. Our results suggest that macrophage Hfe participates in the regulation of splenic and liver iron concentrations and liver hepcidin expression. (Blood. 2005;106:2189-2195)

CBIO-06. CELL INTRINSIC HFE DRIVES SEX-SPECIFIC GLIOBLASTOMA GROWTH

2021 ◽  
Vol 23 (Supplement_6) ◽  
pp. vi28-vi28
Author(s):  
Katie M Troike ◽  
Erin E Mulkearns-Hubert ◽  
Daniel J Silver ◽  
James Connor ◽  
Justin Lathia
Keyword(s):  
Tumor Growth ◽  
Iron Uptake ◽  
Iron Homeostasis ◽  
Iron Status ◽  
Essential Element ◽  
Cell Number ◽  
Hfe Gene ◽  
Dependent Manner

Abstract Iron is an essential element required for a number of cellular processes and can contribute to malignant transformation and tumor expansion. In glioblastoma (GBM), tumor cells have been shown to modulate expression of iron-associated proteins to enhance iron uptake from the surrounding microenvironment, driving proliferation and tumor growth. The homeostatic iron regulatory (HFE) gene encodes a transmembrane glycoprotein that aids in iron homeostasis by modulating iron uptake and release. HFE is upregulated in GBM tumors compared to non-tumor brain and expression of HFE increases with tumor grade. Furthermore, HFE mRNA expression is associated with significantly reduced survival specifically in female patients with GBM. However, it is unclear how HFE impacts sex-specific GBM growth. To interrogate the underlying mechanism of HFE-mediated sex differences, we employed genetic loss and gain of function approaches using syngeneic mouse glioma models. We observed significant alterations in the expression of several iron-associated genes with Hfe knockdown or overexpression, suggesting global disruption of iron homeostasis. We found that knockdown of Hfe decreased cell number and increased apoptosis in vitro and led to a significant impairment of tumor growth in vivo, with a more pronounced effect seen in female mice. Conversely, overexpression of Hfe increased cell number and significantly decreased survival only in female animals. These findings support the hypothesis that Hfe is a critical regulator of cellular iron status and contributes to tumor aggression in a sex-dependent manner. These data also suggest an unexplored link between cell intrinsic iron signaling and sex-specific microenvironmental and immune responses, which is the focus of ongoing studies.

Regulation of transferrin receptor 2 protein levels by transferrin

Blood ◽  
2004 ◽  
Vol 104 (13) ◽  
pp. 4294-4299 ◽  
Author(s):  
Aeisha Robb ◽  
Marianne Wessling-Resnick
Keyword(s):  
Transferrin Receptor ◽  
Iron Status ◽  
Critical Role ◽  
Iron Loading ◽  
Liver Iron ◽  
High Iron ◽  
Protein Levels ◽  
Iron Deficient ◽  
Transferrin Receptor 2

Abstract Transferrin receptor 2 (TfR2) plays a critical role in iron homeostasis because patients carrying disabling mutations in the TFR2 gene suffer from hemochromatosis. In this study, iron-responsive regulation of TfR2 at the protein level was examined in vitro and in vivo. HepG2 cell TfR2 protein levels were up-regulated after exposure to holotransferrin (holoTf) in a time- and dose-responsive manner. ApoTf or high-iron treatment with non–Tf-bound iron failed to elicit similar effects, suggesting that TfR2 regulation reflects interactions of the iron-bound ligand. Hepatic TfR2 protein levels also reflected an adaptive response to changing iron status in vivo. Liver TfR2 protein levels were down- and up-regulated in rats fed an iron-deficient and a high-iron diet, respectively. TfR2 was also up-regulated in Hfe-/- mice, an animal model that displays liver iron loading. In contrast, TfR2 levels were reduced in hypotransferrinemic mice despite liver iron overload, supporting the idea that regulation of the receptor is dependent on Tf. This idea is confirmed by up-regulation of TfR2 in β-thalassemic mice, which, like hypotransferrinemic mice, are anemic and incur iron loading, but have functional Tf. Based on these combined results, we hypothesize that TfR2 acts as a sensor of iron status such that receptor levels reflect Tf saturation.

scholarly journals Matriptase-2 and Hemojuvelin in Hepcidin Regulation: In Vivo Immunoblot Studies in Mask Mice

2021 ◽  
Vol 22 (5) ◽  
pp. 2650
Author(s):  
Jan Krijt ◽  
Jana Frýdlová ◽  
Iuliia Gurieva ◽  
Petr Přikryl ◽  
Martin Báječný ◽  
...  
Keyword(s):  
Proteolytic Activity ◽  
Negative Regulator ◽  
Spleen Weight ◽  
Deficient Diet ◽  
Liver Iron ◽  
Hepcidin Expression ◽  
Stress Erythropoiesis ◽  
Iron Deficient

Matriptase-2, a serine protease expressed in hepatocytes, is a negative regulator of hepcidin expression. The purpose of the study was to investigate the interaction of matriptase-2 with hemojuvelin protein in vivo. Mice lacking the matriptase-2 proteolytic activity (mask mice) display decreased content of hemojuvelin protein. Vice versa, the absence of hemojuvelin results in decreased liver content of matriptase-2, indicating that the two proteins interact. To further characterize the role of matriptase-2, we investigated iron metabolism in mask mice fed experimental diets. Administration of iron-enriched diet increased liver iron stores as well as hepcidin expression. Treatment of iron-overloaded mask mice with erythropoietin increased hemoglobin and hematocrit, indicating that the response to erythropoietin is intact in mask mice. Feeding of an iron-deficient diet to mask mice significantly increased spleen weight as well as the splenic content of erythroferrone and transferrin receptor proteins, indicating stress erythropoiesis. Liver hepcidin expression was decreased; expression of Id1 was not changed. Overall, the results suggest a complex interaction between matriptase-2 and hemojuvelin, and demonstrate that hepcidin can to some extent be regulated even in the absence of matriptase-2 proteolytic activity.

scholarly journals In vivo and in vitro regulation of erythropoietin mRNA: measurement by competitive polymerase chain reaction

Blood ◽  
1993 ◽  
Vol 81 (3) ◽  
pp. 617-623 ◽  
Author(s):  
J Fandrey ◽  
HF Bunn
Keyword(s):  
Polymerase Chain Reaction ◽  
Hepatoma Cell ◽  
Hepatoma Cell Line ◽  
Mrna Levels ◽  
Chain Reaction ◽  
Human Hepatoma Cell ◽  
Competitive Polymerase Chain Reaction ◽  
Polymerase Chain

Abstract The regulation of erythropoietin (Epo) production was investigated by competitive polymerase chain reaction, a highly sensitive and accurate means of measuring Epo mRNA levels. Co-amplification of the test sample with added mutant Epo cDNA template corrects for variability in the efficiency of amplification. Epo mRNA levels were determined in tissues of normal rats and in animals with varying degrees of anemia. Reduction of the hematocrit level from 0.40 to 0.15–0.20 resulted in a 300-fold increase in kidney Epo mRNA, which comprised 80% of the total Epo mRNA versus 20% from the liver. In contrast, very low levels detected in lung and spleen were not significantly increased by anemia. The human hepatoma cell line, Hep3B, secretes high levels of Epo in response to hypoxia. This regulation is, to a large extent, transcriptional. When Hep3B cells were incubated in the presence of decreasing O2 tension from 160 to 7 mm Hg, there was a monotonic increase in Epo mRNA to 50 to 100 times the normoxic level. Hyperoxia did not suppress basal expression. When cells were incubated at a PO2 of 7 mm Hg, induction of Epo mRNA was first noted at 30 minutes and was maximal at 5 to 6 hours. After Epo mRNA was boosted by a 4-hour hypoxic incubation, cells were then exposed to normoxia, which shut off further transcription of the Epo gene. The decay of Epo mRNA levels closely followed first order kinetics with a half-life of 2 hours, an effective measurement of message stability.

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