IRP1 regulates erythropoiesis and systemic iron homeostasis by controlling HIF2α mRNA translation

Key Points IRP1 controls HIF2α mRNA translation in vivo and thereby acts as an upstream regulator of Epo expression. IRP1 deficiency leads to age-dependent erythropoietic abnormalities and misregulation of body iron metabolism via the HIF2α/Epo pathway.

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Targeted disruption of hepcidin in the liver recapitulates the hemochromatotic phenotype

Blood ◽

10.1182/blood-2014-01-550467 ◽

2014 ◽

Vol 123 (23) ◽

pp. 3646-3650 ◽

Cited By ~ 45

Author(s):

Sara Zumerle ◽

Jacques R. R. Mathieu ◽

Stéphanie Delga ◽

Mylène Heinis ◽

Lydie Viatte ◽

...

Keyword(s):

Iron Overload ◽

Iron Homeostasis ◽

Targeted Disruption ◽

Body Iron ◽

Key Points ◽

Main Regulator

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.

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Hepcidin in Iron Homeostasis: Diagnostic and Therapeutic Implications in Type 2 Diabetes Mellitus Patients

Acta Haematologica ◽

10.1159/000481391 ◽

2017 ◽

Vol 138 (4) ◽

pp. 183-193 ◽

Cited By ~ 4

Author(s):

Sintayehu Ambachew ◽

Belete Biadgo

Keyword(s):

Diabetes Mellitus ◽

Type 2 Diabetes ◽

Type 2 Diabetes Mellitus ◽

Iron Overload ◽

Iron Metabolism ◽

Iron Homeostasis ◽

Diabetic Patients ◽

Hepatitis C Infection ◽

Body Iron

The prevalence of type 2 diabetes is increasing in epidemic proportions worldwide. Evidence suggests body iron overload is frequently linked and observed in patients with type 2 diabetes. Body iron metabolism is based on iron conservation and recycling by which only a part of the daily need is replaced by duodenal absorption. The principal liver-produced peptide called hepcidin plays a fundamental role in iron metabolism. It directly binds to ferroportin, the sole iron exporter, resulting in the internalization and degradation of ferroportin. However, inappropriate production of hepcidin has been shown to play a role in the pathogenesis of type 2 diabetes mellitus and its complications, based on the regulation and expression in iron-abundant cells. Underexpression of hepcidin results in body iron overload, which triggers the production of reactive oxygen species simultaneously thought to play a major role in diabetes pathogenesis mediated both by β-cell failure and insulin resistance. Increased hepcidin expression results in increased intracellular sequestration of iron, and is associated with the complications of type 2 diabetes. Besides, hepcidin concentrations have been linked to inflammatory cytokines, matriptase 2, and chronic hepatitis C infection, which have in turn been reported to be associated with diabetes by several approaches. Either hepcidin-targeted therapy alone or as adjunctive therapy with phlebotomy, iron chelators, or dietary iron restriction may be able to alter iron parameters in diabetic patients. Therefore, measuring hepcidin may improve differential diagnosis and the monitoring of disorders of iron metabolism.

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Iron-Response Element Binding to Iron Regulatory Protein (IRP) 1 and 2 Are Indispensable for Adipose Tissue Browning

Current Developments in Nutrition ◽

10.1093/cdn/nzaa058_041 ◽

2020 ◽

Vol 4 (Supplement_2) ◽

pp. 1283-1283

Author(s):

Mikyoung You ◽

Soonkyu Chung

Keyword(s):

Adipose Tissue ◽

Iron Metabolism ◽

Knockout Mice ◽

Iron Homeostasis ◽

Regulatory Protein ◽

Mrna Translation ◽

Intracellular Iron ◽

Mobility Shift ◽

Iron Regulatory Proteins ◽

Tissue Browning

Abstract Objectives Intracellular iron homeostasis is tightly regulated in posttranscriptional levels via iron regulatory proteins (IRPs). IRPs bind to the iron-responsive elements (IREs), leading to either mRNA translation or stability. Our recent study demonstrated that iron metabolism is intimately linked with adipose tissue browning and thermogenic activation. However, the role of IRP/IRE interactions in the adipose tissue is poorly understood. We aim to characterize the IRP/IRE interactions in the adipose tissue in terms of depot-specificity and thermogenic potential. Methods To induce adipocyte browning, mice were administrated with beta-3 adrenoceptor agonist CL316243 (CL) for 5 days, and different depots of adipose tissue of epididymal (eWAT), inguinal (iWAT), brown (BAT), and liver were collected. Iron metabolism and thermogenesis were evaluated. To investigate the IRP/IRE binding, electrophoretic mobility shift assay (EMSA) was performed in the cytosolic using the fluorescence-labeled IRE (IR-IRE). To distinguish the IRE binding with IRP1 and 2, the cytosolic fraction from IRP1 and 2 knockout mice were used as positive controls. Results In a normal temperature, the constitutive IRP/IRE binding was found in the BAT, but not in the eWAT and iWAT. In response to CL treatment, iron content and transferrin receptor levels significantly increased in the WAT. Accordingly, the IRE/IRPs binding significantly increased in the CL-treated iWAT. Genetic deletion of IRP1 or 2 poses a marginal impact on constitutively active BAT development, suggesting IRP1 and 2 plays a compensatory role. Unlikely to BAT, the deletion of either IRP1 or 2 failed to induce WAT browning in the IRP1 and 2 knockout mice with CL stimulation. Consistently, both IRE binding to IRP1 and 2 were manifest in the CL treated iWAT, implicating that IRP1 and 2 plays a separate and synergistic function for WAT browning. Conclusions Our study defined the depot-specific iron regulatory metabolism in the adipose tissue using an innovative EMSA method. We demonstrated that, for the first time in our knowledge, IRE binding to both IRP1 and IRP2 is indispensable for the thermogenic activation of WAT, which is distinct from the iron regulatory mechanism found in the BAT. We propose that iron metabolism in the WAT is a novel determinant for WAT browning and thermogenic energy expenditure. Funding Sources None.

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Iron regulatory proteins and their role in controlling iron metabolism

Metallomics ◽

10.1039/c4mt00164h ◽

2015 ◽

Vol 7 (2) ◽

pp. 232-243 ◽

Cited By ~ 103

Author(s):

Lukas C. Kühn

Keyword(s):

Iron Metabolism ◽

Iron Uptake ◽

Iron Homeostasis ◽

Regulatory Proteins ◽

Feedback Mechanisms ◽

Iron Regulatory Proteins ◽

Body Iron ◽

Transcriptional Feedback

Cellular and body iron homeostasis are regulated by iron-sensing and post-transcriptional feedback mechanisms, which control iron uptake, release, storage and heme biosythesis.

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Iron Metabolism In Macrophages In Non Transfusion Dependent Thalassemia

Blood ◽

10.1182/blood.v122.21.4669.4669 ◽

2013 ◽

Vol 122 (21) ◽

pp. 4669-4669

Author(s):

Valentina Vaja ◽

Elena Paltrinieri ◽

Irene Motta ◽

Erika Poggiali ◽

Alessia Marcon ◽

...

Keyword(s):

Gene Expression ◽

Iron Metabolism ◽

Iron Homeostasis ◽

Conflicts Of Interest ◽

Iron Concentration ◽

Divalent Metal Transporter 1 ◽

Expression Levels ◽

Significant Difference ◽

Gene Expression Levels

Background β-thalassemia is a disease characterized by alteration of β-globin chains production. The phenotype is associated with development of anemia, ineffective erythropoiesis (IE), and iron overload. Cellular iron homeostasis in macrophages is regulated at multiple steps and by numerous genes. Macrophages can acquire iron by Transferrin receptor 1-mediated uptake of transferrin-bound iron, acquisition of molecular iron via the divalent metal transporter 1 (Dmt1) and phagocytosis of senescent erythrocytes with subsequent recycling of iron. There is only one well-characterized pathway by which iron can exit cells, ferroportin-1 (Fpn1), which is expressed on the cell surface of macrophages and acts as the exclusive trans-membrane export protein for ferrous (Fe2+) iron. Hepcidin, a mainly liver-derived peptide induced by iron and cytokines and master regulator of body iron homeostasis, exerts its regulatory effects via binding to Fpn1, which is thought to be the hepcidin receptor. This interaction results in Fpn1 internalization, proteasomal degradation and blockage of iron export. Little is known about what happens at the level of macrophages in thalassemic patients and how they face the high iron concentration. The aim of this study was to characterize the differential expression of the genes involved in iron homeostasis and changes in iron trafficking in fully differentiated unpolarized (M0) human macrophages in Non Transfusion Dependent Thalassemia (NTDT) patients. Methods Monocytes were purified using positive selection with CD14-coated magnetic beads (Miltenyi Biotec) from peripheral blood of 7 NTDT patients and 7 healthy normal controls. Monocytes were cultured for 6 days in RPMI containing 10% FBS and 25 ng/ml GM-CSF and differentiated in mature macrophages. The expression of specific macrophages surface proteins was analyzed by flow cytometry. We used immunohistochemistry to evaluate differentiation and iron retention of macrophages. For basic morphology characterization, formalin-fixed cells were stained using hematoxylin and eosin staining. Iron was detected with DAB-enhanced Perls' staining (Prussian blue reaction). Total mRNA was extracted from cultured cells and gene expression profile was analyzed by real-time PCR using Taqman-probes technologies. Results The purity of the resulting cells suspension was tested by fluorescent-activated cell sorting analysis and was beyond 98%. The cell morphology of macrophages showed no differences between control and thalassemic patients. Using immunohistochemistry iron was not detected in human cultured macrophages of thalassemia patients and controls. We characterized the expression of genes related to iron homeostasis. We analyzed the gene expression levels of SLC40A1 (Ferroportin) , SLC11A2 (Dmt1), HAMP (Hepcidin) that are directly involved in macrophage iron traffic and these results show no statistical differences between patients and controls. Conclusions Due to the heterogeneity of the cellular morphology of macrophages there was no significant difference between the macrophages morphology from NTDT and controls. Iron was not present in M0 magrophages. The gene expression levels of ferroportin, Dmt1 and Hepcidin in mature macrophages grown in regular culture medium without other stimuli were comparable between controls and patients. This culture system does not reflect the in vivo iron metabolism of thalassemic patients due to possibly monocytes inability to internalize and accumulate iron. Different stimuli are necessary to simulate the in vivo condition to differentiate the macrophages. Cells of the monocyte-macrophage lineage are characterized by marked phenotypical and functional heterogeneity. Classical activation by microbial agents and/or Th1 cytokines is associated with the production of oxygen radicals and the pro-inflammatory cytokines involved in cytotoxicity and microbial killing (M1 polarization), but macrophages can also follow a different activation pathway after stimulation with the Th2 cytokines IL-4 or IL-13 (M2 polarization). We will therefore investigate whether iron homeostasis is regulated differently in M1 and M2 macrophages and possibly provide a better understanding of the changes in iron metabolism that take place under thalassemia condition. Disclosures: No relevant conflicts of interest to declare.

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Iron Overload contributes to General Anesthesia-induced Neurotoxicity and Cognitive Deficits

10.21203/rs.2.18898/v1 ◽

2019 ◽

Author(s):

Jing Wu ◽

Shuofei Yang ◽

Yan Cao ◽

Huihui Li ◽

Hongting Zhao ◽

...

Keyword(s):

Iron Overload ◽

General Anesthesia ◽

Iron Metabolism ◽

Cognitive Deficits ◽

Hippocampal Neurons ◽

Iron Homeostasis ◽

Novel Therapy ◽

The Impact

Abstract Background Increasing evidence suggests that exposure to general anesthesia (GA) could be detrimental to cognitive development in young subjects, and might also contribute to accelerated neurodegeneration in the elderly. Iron is essential for normal neuronal function and excess iron in brain is a hallmark of neuroinflammation and is implicated in several neurodegenerative diseases. However, the role of iron in GA-induced neurotoxicity and cognitive deficits has not been studied.Methods We used the primary hippocampal neurons and rodents including young rats and aged mice to examine whether GA impacts iron metabolism and whether the impact contributed to neuronal outcomes. In addition, a pharmacological suppression of iron metabolism was performed to explore the molecular mechanism underlying GAs-mediated iron overload in the brain.Results Our results demonstrated that GA, induced by intravenous ketamine or inhalational sevoflurane, disturbed iron homeostasis and caused iron overload in both in vitro hippocampal neuron culture and in vivo hippocampus. Interestingly, ketamine or sevoflurane-induced cognitive deficits, very likely, result from a novel regulated iron-dependent cell death, ferroptosis. Notably, iron chelator deferiprone attenuated the GA-induced mitochondrial dysfunctions, ferroptosis, and further cognitive deficits. Moreover, we found that GA-induced iron overload was activated by NMDAR-RASD1 signalling via DMT1 action in the brain.Conclusion We conclude that disturbed iron metabolism may be involved in the pathogenesis of GA-induced neurotoxicity and cognitive deficits. Our study provides new insights into a potential novel therapy for prevention in GA-associated neurological disorders.

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Melittin Regulates Iron Homeostasis as a Key Mediator of Macrophage Polarization in Rat Lumbar Spinal Stenosis

10.21203/rs.3.rs-1194869/v1 ◽

2021 ◽

Author(s):

Hyunseong Kim ◽

Jin Young Hong ◽

Wan-Jin Jeon ◽

Junseon Lee ◽

Yoon Jae Lee ◽

...

Keyword(s):

Spinal Stenosis ◽

Iron Metabolism ◽

Iron Homeostasis ◽

Macrophage Polarization ◽

M2 Macrophages ◽

Iron Release ◽

Locomotor Recovery ◽

Lumbar Spinal

Abstract BackgroundLumbar spinal stenosis (LSS) is defined as the narrowing of the spinal canal, which compresses the nerves traveling through the lower back into the legs. Inflammation is the most common cause of LSS. Chronic pain induced by nerve damage results from chronic inflammation, and the inflammation response worsens with elevated iron stores. Furthermore, macrophage polarization to the M1 (inflammatory) or M2 (anti-inflammatory) type is essential for controlling host defense or repairing tissues. However, the precise function of macrophage polarization in iron release or retention in LSS pathophysiology is not well-understood. Here, we introduce melittin to modulate macrophage polarization related to iron metabolism for LSS treatment.MethodsPrimary peritoneal macrophage were cultured in 200 or 500 ng/mL of melittin and FeSO4-containing medium for 24 h. Macrophage polarization was assessed by Immunofluorescence staining to CD86 or Arg1 antibodies. In an in vivo rat model of LSS, melittin were administered at 100 and 250 µg/kg, and in vivo effects of melittin on iron deposition-induced macrophage polarization was evaluated by immunochemistry, real time-PCR, western blot, and flow-cytometry. The locomotor functions were assessed by BBB, ladder scoring, and Von Frey test for up to 3 weeks. ResultsIn vitro experiments demonstrated that macrophages can be polarized toward an M2 phenotype after melittin treatment in iron-insulted primary macrophages. Treatment with 100 and 250 μg/kg melittin in a rat LSS model increased the proportion of M2 macrophages in the damaged spinal cord. Moreover, we found that melittin attenuated iron overload-induced M1 polarization via regulating iron metabolism-related genes in LSS rats. As a result, melittin improved locomotor recovery and stimulated axonal growth following LSS.ConclusionsMelittin can promote functional recovery in LSS models by activating M2 macrophages via controlling macrophage iron metabolism, suggesting the potential applications of melittin for treating LSS.

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Iron Overload contributes to General Anesthesia-induced Neurotoxicity and Cognitive Deficits

10.21203/rs.2.18898/v2 ◽

2020 ◽

Author(s):

Jing Wu ◽

Jian-Jun Yang ◽

Yan Cao ◽

Huihui Li ◽

Hongting Zhao ◽

...

Keyword(s):

Iron Overload ◽

General Anesthesia ◽

Iron Metabolism ◽

Cognitive Deficits ◽

Hippocampal Neurons ◽

Iron Homeostasis ◽

The Impact ◽

The Brain

Abstract Background: Increasing evidence suggests that multiple or long-time exposure to general anesthesia (GA) could be detrimental to cognitive development in young subjects, and might also contribute to accelerated neurodegeneration in the elderly. Iron is essential for normal neuronal function and excess iron in brain is implicated in several neurodegenerative diseases. However, the role of iron in GA-induced neurotoxicity and cognitive deficits remains elusive. Methods: We used the primary hippocampal neurons and rodents including young rats and aged mice to examine whether GA impacted iron metabolism and whether the impact contributed to neuronal outcomes. In addition, a pharmacological suppression of iron metabolism was performed to explore the molecular mechanism underlying GAs-mediated iron overload in the brain. Results: Our results demonstrated that GA, induced by intravenous ketamine or inhalational sevoflurane, disturbed iron homeostasis and caused iron overload in both in vitro hippocampal neuron culture and in vivo hippocampus. Interestingly, ketamine or sevoflurane-induced cognitive deficits, very likely, resulted from a novel iron-dependent regulated cell death, ferroptosis. Notably, iron chelator deferiprone attenuated the GA-induced mitochondrial dysfunction, ferroptosis, and further cognitive deficits. Moreover, we found that GA-induced iron overload was activated by NMDAR-RASD1 signalling via DMT1 action in the brain. Conclusion: We conclude that disturbed iron metabolism may be involved in the pathogenesis of GA-induced neurotoxicity and cognitive deficits. Our study provides new vision for consideration in GA-associated neurological disorders.

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