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Enns CA, Weiskopf T, Zhang RH, Wu J, Jue S, Kawaguchi M, Kataoka H, Zhang AS. Matriptase-2 regulates iron homeostasis primarily by setting the basal levels of hepatic hepcidin expression through a nonproteolytic mechanism. J Biol Chem 2023; 299:105238. [PMID: 37690687 PMCID: PMC10551898 DOI: 10.1016/j.jbc.2023.105238] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Revised: 08/07/2023] [Accepted: 08/23/2023] [Indexed: 09/12/2023] Open
Abstract
Matriptase-2 (MT2), encoded by TMPRSS6, is a membrane-anchored serine protease. It plays a key role in iron homeostasis by suppressing the iron-regulatory hormone, hepcidin. Lack of functional MT2 results in an inappropriately high hepcidin and iron-refractory iron-deficiency anemia. Mt2 cleaves multiple components of the hepcidin-induction pathway in vitro. It is inhibited by the membrane-anchored serine protease inhibitor, Hai-2. Earlier in vivo studies show that Mt2 can suppress hepcidin expression independently of its proteolytic activity. In this study, our data indicate that hepatic Mt2 was a limiting factor in suppressing hepcidin. Studies in Tmprss6-/- mice revealed that increases in dietary iron to ∼0.5% were sufficient to overcome the high hepcidin barrier and to correct iron-deficiency anemia. Interestingly, the increased iron in Tmprss6-/- mice was able to further upregulate hepcidin expression to a similar magnitude as in wild-type mice. These results suggest that a lack of Mt2 does not impact the iron induction of hepcidin. Additional studies of wild-type Mt2 and the proteolytic-dead form, fMt2S762A, indicated that the function of Mt2 is to lower the basal levels of hepcidin expression in a manner that primarily relies on its nonproteolytic role. This idea is supported by the studies in mice with the hepatocyte-specific ablation of Hai-2, which showed a marginal impact on iron homeostasis and no significant effects on iron regulation of hepcidin. Together, these observations suggest that the function of Mt2 is to set the basal levels of hepcidin expression and that this process is primarily accomplished through a nonproteolytic mechanism.
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Affiliation(s)
- Caroline A Enns
- Department of Cell, Developmental, and Cancer Biology, Oregon Health & Science University, Portland, Oregon, USA
| | - Tyler Weiskopf
- Department of Cell, Developmental, and Cancer Biology, Oregon Health & Science University, Portland, Oregon, USA
| | - Richard H Zhang
- Department of Cell, Developmental, and Cancer Biology, Oregon Health & Science University, Portland, Oregon, USA
| | - Jeffrey Wu
- Department of Cell, Developmental, and Cancer Biology, Oregon Health & Science University, Portland, Oregon, USA
| | - Shall Jue
- Department of Cell, Developmental, and Cancer Biology, Oregon Health & Science University, Portland, Oregon, USA
| | - Makiko Kawaguchi
- Faculty of Medicine, Section of Oncopathology and Regenerative Biology, Department of Pathology, University of Miyazaki, Miyazaki, Japan
| | - Hiroaki Kataoka
- Faculty of Medicine, Section of Oncopathology and Regenerative Biology, Department of Pathology, University of Miyazaki, Miyazaki, Japan
| | - An-Sheng Zhang
- Department of Cell, Developmental, and Cancer Biology, Oregon Health & Science University, Portland, Oregon, USA.
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2
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Han P, Liu T, Vaquette C, Frazer D, Anderson G, Ivanovski S. Iron accumulation is associated with periodontal destruction in a mouse model of HFE-related haemochromatosis. J Periodontal Res 2021; 57:294-304. [PMID: 34855211 DOI: 10.1111/jre.12959] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Revised: 11/03/2021] [Accepted: 11/17/2021] [Indexed: 12/17/2022]
Abstract
OBJECTIVE To investigate the effect of Hfe gene mutation on the distribution of iron and periodontal bone loss in periodontal tissues. BACKGROUND DATA It remains unclear how tissue iron loading affects the periodontium architectures in a genetic animal model of hereditary haemochromatosis (HH). METHODS Male C57BL/6 Hfe-/- (8 weeks old) and wild-type (WT) mice were utilized to examine the iron distribution in periodontal tissues, as well as periodontal tissues changes using micro-computed tomography and histomorphometric analysis. Furthermore, tissue inflammatory mediators, bone markers and periodontal pathogens were carried out in PFA-fixed paraffin-embedded tissues using ELISA, RT-qPCR and genomic DNA qPCR, respectively. RESULTS Excessive iron deposition was found in the periodontal ligament, gingiva and alveolar bone in Hfe-/- mice relative to their WT counterparts. This, in turn, was associated with significant periodontal bone loss, increased cemento-enamel junction-alveolar bone crest distance and decreased expression of molecules involved in bone development and turnover. Furthermore, the pro-inflammatory cytokine - interleukin 6 and periodontal bacteria - Campylobacter rectus were significantly increased in Hfe-/- mice compared with WT controls. CONCLUSION Our results suggest that the iron loading in a mouse model of HH decreases alveolar bone formation and leads to alterations in the inflammatory state in the periodontium. Periodontal health should be assessed during the clinical assessment of HFE-HH patients.
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Affiliation(s)
- Pingping Han
- School of Dentistry, Centre for Orofacial Regeneration, Reconstruction and Rehabilitation (COR3), Epigenetics Nanodiagnostics and therapeutics Group, The University of Queensland, Herston, QLD, Australia.,School of Dentistry, The University of Queensland, Herston, QLD, Australia
| | - Tianqing Liu
- QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia
| | - Cedryck Vaquette
- School of Dentistry, The University of Queensland, Herston, QLD, Australia
| | - David Frazer
- QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia
| | - Gregory Anderson
- QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia.,School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, QLD, Australia
| | - Sašo Ivanovski
- School of Dentistry, Centre for Orofacial Regeneration, Reconstruction and Rehabilitation (COR3), Epigenetics Nanodiagnostics and therapeutics Group, The University of Queensland, Herston, QLD, Australia.,School of Dentistry, The University of Queensland, Herston, QLD, Australia
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3
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Wang X, Singh AK, Sun W. Protection and Safety Evaluation of Live Constructions Derived from the Pgm - and pPCP1 - Yersinia pestis Strain. Vaccines (Basel) 2020; 8:E95. [PMID: 32098032 PMCID: PMC7157699 DOI: 10.3390/vaccines8010095] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2020] [Revised: 02/18/2020] [Accepted: 02/18/2020] [Indexed: 12/16/2022] Open
Abstract
Based on a live attenuated Yersinia pestis KIM10(pCD1Ap) strain (Pgm-, pPCP1-), we attempted to engineer its lipid A species to achieve improvement of immunogenicity and safety. A mutant strain designated as YPS19(pCD1Ap), mainly synthesizing the hexa-acylated lipid A, and another mutant strain designated as YPS20(pCD1Ap), synthesizing 1-dephosphalated hexa-acylated lipid A (detoxified lipid A), presented relatively low virulence in comparison to KIM10(pCD1Ap) by intramuscular (i.m.) or subcutaneous (s.c.) administration. The i.m. administration with either the KIM10(pCD1Ap) or YPS19(pCD1Ap) strain afforded significant protection against bubonic and pneumonic plague compared to the s.c. administration, while administration with completely attenuated YPS20(pCD1Ap) strain failed to afford significant protection. Antibody analysis showed that i.m. administration induced balanced Th1 and Th2 responses but s.c. administration stimulated Th2-biased responses. Safety evaluation showed that YPS19(pCD1Ap) was relatively safer than its parent KIM10(pCD1Ap) in Hfe-/- mice manifesting iron overload in tissues, which also did not impair its protection. Therefore, the immune activity of hexa-acylated lipid A can be harnessed for rationally designing bacteria-derived vaccines.
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Affiliation(s)
| | | | - Wei Sun
- Department of Immunology and Microbial Disease, Albany Medical College, Albany, NY 12208, USA; (X.W.); (A.K.S.)
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4
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Parmar JH, Mendes P. A computational model to understand mouse iron physiology and disease. PLoS Comput Biol 2019; 15:e1006680. [PMID: 30608934 PMCID: PMC6334977 DOI: 10.1371/journal.pcbi.1006680] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Revised: 01/16/2019] [Accepted: 11/29/2018] [Indexed: 12/16/2022] Open
Abstract
It is well known that iron is an essential element for life but is toxic when in excess or in certain forms. Accordingly there are many diseases that result directly from either lack or excess of iron. Yet many molecular and physiological aspects of iron regulation have only been discovered recently and others are still elusive. There is still no good quantitative and dynamic description of iron absorption, distribution, storage and mobilization that agrees with the wide array of phenotypes presented in several iron-related diseases. The present work addresses this issue by developing a mathematical model of iron distribution in mice calibrated with ferrokinetic data and subsequently validated against data from mouse models of iron disorders, such as hemochromatosis, β-thalassemia, atransferrinemia and anemia of inflammation. To adequately fit the ferrokinetic data required inclusion of the following mechanisms: a) transferrin-mediated iron delivery to tissues, b) induction of hepcidin by transferrin-bound iron, c) ferroportin-dependent iron export regulated by hepcidin, d) erythropoietin regulation of erythropoiesis, and e) liver uptake of NTBI. The utility of the model to simulate disease interventions was demonstrated by using it to investigate the outcome of different schedules of transferrin treatment in β-thalassemia. Iron is an essential nutrient in almost all life forms. In humans and animals iron is used for respiration and for transporting oxygen inside red blood cells. But in excess iron can be toxic and therefore the body regulates its distribution and absortion through the action of hormones, which is not yet completely understood. Here we created a computational model of the regulation of iron distribution in the body of a mouse based on experimental data. The model can accurately simulate many iron diseases such as anemia, hemochromatosis, and thalassemia. This computational model is helpful to understand the basis of these diseases and plan therapies to address them.
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Affiliation(s)
- Jignesh H. Parmar
- Center for Quantitative Medicine and Department of Cell Biology, University of Connecticut School of Medicine, Farmington, Connecticut, United States of America
| | - Pedro Mendes
- Center for Quantitative Medicine and Department of Cell Biology, University of Connecticut School of Medicine, Farmington, Connecticut, United States of America
- * E-mail:
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5
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Sukhbaatar N, Weichhart T. Iron Regulation: Macrophages in Control. Pharmaceuticals (Basel) 2018; 11:ph11040137. [PMID: 30558109 PMCID: PMC6316009 DOI: 10.3390/ph11040137] [Citation(s) in RCA: 105] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Revised: 12/10/2018] [Accepted: 12/12/2018] [Indexed: 12/21/2022] Open
Abstract
Macrophages are sentinel cells of the innate immune system and have important functions in development, tissue homeostasis, and immunity. These phylogenetically ancient cells also developed a variety of mechanisms to control erythropoiesis and the handling of iron. Red pulp macrophages in the spleen, Kupffer cells in the liver, and central nurse macrophages in the bone marrow ensure a coordinated metabolism of iron to support erythropoiesis. Phagocytosis of senescent red blood cells by macrophages in the spleen and the liver provide a continuous delivery of recycled iron under steady-state conditions and during anemic stress. Central nurse macrophages in the bone marrow utilize this iron and provide a cellular scaffold and niche to promote differentiation of erythroblasts. This review focuses on the role of the distinct macrophage populations that contribute to efficient iron metabolism and highlight important cellular and systemic mechanisms involved in iron-regulating processes.
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Affiliation(s)
- Nyamdelger Sukhbaatar
- Medical University of Vienna, Center for Pathobiochemistry and Genetics, Vienna 1090, Austria.
| | - Thomas Weichhart
- Medical University of Vienna, Center for Pathobiochemistry and Genetics, Vienna 1090, Austria.
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6
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Nixon AM, Meadowcroft MD, Neely EB, Snyder AM, Purnell CJ, Wright J, Lamendella R, Nandar W, Huang X, Connor JR. HFE Genotype Restricts the Response to Paraquat in a Mouse Model of Neurotoxicity. J Neurochem 2018; 145:299-311. [PMID: 29315562 DOI: 10.1111/jnc.14299] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Revised: 12/05/2017] [Accepted: 01/03/2018] [Indexed: 12/30/2022]
Abstract
Parkinson's disease is marked clinically by motor dysfunction and pathologically by dopaminergic cell loss in the substantia nigra and iron accumulation in the substantia nigra. The driver underlying iron accumulation remains unknown and could be genetic or environmental. The HFE protein is critical for the regulation of cellular iron uptake. Mutations within this protein are associated with increased iron accumulation including in the brain. We have focused on the commonly occurring H63D variant of the HFE gene as a disease modifier in a number of neurodegenerative diseases. To investigate the role of H63D HFE genotype, we generated a mouse model in which the wild-type (WT) HFE gene is replaced by the H67D gene variant (mouse homolog of the human H63D gene variant). Using paraquat toxicity as the model for Parkinson's disease, we found that WT mice responded as expected with significantly greater motor function, loss of tyrosine hydroxylase staining and increase microglial staining in the substantia nigra, and an increase in R2 relaxation rate within the substantia nigra of the paraquat-treated mice compared to their saline-treated counterparts. In contrast, the H67D mice showed a remarkable resistance to paraquat treatment; specifically differing from the WT mice with no changes in motor function or changes in R2 relaxation rates following paraquat exposure. At baseline, there were differences between the H67D HFE mice and WT mice in gut microbiome profile and increased L-ferritin staining in the substantia nigra that could account for the resistance to paraquat. Of particular note, the H67D HFE mice regardless of whether or not they were treated with paraquat had significantly less tyrosine hydroxylase immunostaining than WT. Our results clearly demonstrate that the HFE genotype impacts the expression of tyrosine hydroxylase in the substantia nigra, the gut microbiome and the response to paraquat providing additional support that the HFE genotype is a disease modifier for Parkinson's disease. Moreover, the finding that the HFE mutant mice are resistant to paraquat may provide a model in which to study resistant mechanisms to neurotoxicants.
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Affiliation(s)
- Anne M Nixon
- Department of Neurosurgery, M.S. Hershey Penn State University College of Medicine, M.S. Hershey Medical Center, Hershey, Pennsylvania, USA
| | - Mark D Meadowcroft
- Department of Neurosurgery, M.S. Hershey Penn State University College of Medicine, M.S. Hershey Medical Center, Hershey, Pennsylvania, USA
- Department of Radiology, M.S. Hershey Penn State University College of Medicine, M.S. Hershey Medical Center, Hershey, Pennsylvania, USA
| | - Elizabeth B Neely
- Department of Neurosurgery, M.S. Hershey Penn State University College of Medicine, M.S. Hershey Medical Center, Hershey, Pennsylvania, USA
| | - Amanda M Snyder
- Department of Neurosurgery, M.S. Hershey Penn State University College of Medicine, M.S. Hershey Medical Center, Hershey, Pennsylvania, USA
| | - Carson J Purnell
- Department of Neurosurgery, M.S. Hershey Penn State University College of Medicine, M.S. Hershey Medical Center, Hershey, Pennsylvania, USA
| | | | - Regina Lamendella
- Wright Labs, Huntingdon, Pennsylvania, USA
- Department of Microbiology, Juniata College, Huntingdon, Pennsylvania, USA
| | - Wint Nandar
- Department of Sports Medicine and Nutrition, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Xuemei Huang
- Department of Neurology, M.S. Hershey Penn State University College of Medicine, M.S. Hershey Medical Center, Hershey, Pennsylvania, USA
| | - James R Connor
- Department of Neurosurgery, M.S. Hershey Penn State University College of Medicine, M.S. Hershey Medical Center, Hershey, Pennsylvania, USA
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7
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Vaugier C, Amano MT, Chemouny JM, Dussiot M, Berrou C, Matignon M, Ben Mkaddem S, Wang PHM, Fricot A, Maciel TT, Grapton D, Mathieu JRR, Beaumont C, Peraldi MN, Peyssonnaux C, Mesnard L, Daugas E, Vrtovsnik F, Monteiro RC, Hermine O, Ginzburg YZ, Benhamou M, Camara NOS, Flamant M, Moura IC. Serum Iron Protects from Renal Postischemic Injury. J Am Soc Nephrol 2017; 28:3605-3615. [PMID: 28784700 DOI: 10.1681/asn.2016080926] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Accepted: 06/30/2017] [Indexed: 01/09/2023] Open
Abstract
Renal transplants remain a medical challenge, because the parameters governing allograft outcome are incompletely identified. Here, we investigated the role of serum iron in the sterile inflammation that follows kidney ischemia-reperfusion injury. In a retrospective cohort study of renal allograft recipients (n=169), increased baseline levels of serum ferritin reliably predicted a positive outcome for allografts, particularly in elderly patients. In mice, systemic iron overload protected against renal ischemia-reperfusion injury-associated sterile inflammation. Furthermore, chronic iron injection in mice prevented macrophage recruitment after inflammatory stimuli. Macrophages cultured in high-iron conditions had reduced responses to Toll-like receptor-2, -3, and -4 agonists, which associated with decreased reactive oxygen species production, increased nuclear localization of the NRF2 transcription factor, increased expression of the NRF2-related antioxidant response genes, and limited NF-κB and proinflammatory signaling. In macrophage-depleted animals, the infusion of macrophages cultured in high-iron conditions did not reconstitute AKI after ischemia-reperfusion, whereas macrophages cultured in physiologic iron conditions did. These findings identify serum iron as a critical protective factor in renal allograft outcome. Increasing serum iron levels in patients may thus improve prognosis of renal transplants.
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Affiliation(s)
- Céline Vaugier
- Institut National de la Santé et de la Recherche Médicale Unité Mixte de Recherche (UMR)1163, Paris, France.,Sorbonne Paris Cité, Université René Descartes, Imagine Institute, Paris, France.,Centre National de la Recherche Scientifique Equipe de Recherche Labellisée (ERL)8254, Paris, France.,Laboratoire d'excellence GR-Ex, Paris, France
| | - Mariane T Amano
- Laboratory of Transplantation Immunobiology, Department of Immunology, Institute of Biomedical Sciences IV, University of São Paulo, Sao Paulo, Brazil
| | - Jonathan M Chemouny
- Université Denis-Diderot, Laboratoire d'excellence INFLAMEX, Paris, France.,UMR1149, Paris, France.,ERL8252, Paris, France.,Departments of Nephrology
| | - Michael Dussiot
- Institut National de la Santé et de la Recherche Médicale Unité Mixte de Recherche (UMR)1163, Paris, France.,Sorbonne Paris Cité, Université René Descartes, Imagine Institute, Paris, France.,Centre National de la Recherche Scientifique Equipe de Recherche Labellisée (ERL)8254, Paris, France.,Laboratoire d'excellence GR-Ex, Paris, France
| | - Claire Berrou
- Institut National de la Santé et de la Recherche Médicale Unité Mixte de Recherche (UMR)1163, Paris, France.,Sorbonne Paris Cité, Université René Descartes, Imagine Institute, Paris, France.,Centre National de la Recherche Scientifique Equipe de Recherche Labellisée (ERL)8254, Paris, France.,Laboratoire d'excellence GR-Ex, Paris, France
| | - Marie Matignon
- Department of Nephrology and Transplantation, AP-HP, Hôpital Henri Mondor, Institut Francilien de recherche en Néphrologie et Transplantation, Paris-Est Université, Creteil, France
| | - Sanae Ben Mkaddem
- Université Denis-Diderot, Laboratoire d'excellence INFLAMEX, Paris, France.,UMR1149, Paris, France.,ERL8252, Paris, France
| | - Pamella H M Wang
- Institut National de la Santé et de la Recherche Médicale Unité Mixte de Recherche (UMR)1163, Paris, France.,Sorbonne Paris Cité, Université René Descartes, Imagine Institute, Paris, France.,Centre National de la Recherche Scientifique Equipe de Recherche Labellisée (ERL)8254, Paris, France.,Laboratoire d'excellence GR-Ex, Paris, France
| | - Aurélie Fricot
- Institut National de la Santé et de la Recherche Médicale Unité Mixte de Recherche (UMR)1163, Paris, France.,Sorbonne Paris Cité, Université René Descartes, Imagine Institute, Paris, France.,Centre National de la Recherche Scientifique Equipe de Recherche Labellisée (ERL)8254, Paris, France.,Laboratoire d'excellence GR-Ex, Paris, France
| | - Thiago T Maciel
- Institut National de la Santé et de la Recherche Médicale Unité Mixte de Recherche (UMR)1163, Paris, France.,Sorbonne Paris Cité, Université René Descartes, Imagine Institute, Paris, France.,Centre National de la Recherche Scientifique Equipe de Recherche Labellisée (ERL)8254, Paris, France.,Laboratoire d'excellence GR-Ex, Paris, France
| | - Damien Grapton
- Institut National de la Santé et de la Recherche Médicale Unité Mixte de Recherche (UMR)1163, Paris, France.,Sorbonne Paris Cité, Université René Descartes, Imagine Institute, Paris, France.,Centre National de la Recherche Scientifique Equipe de Recherche Labellisée (ERL)8254, Paris, France.,Laboratoire d'excellence GR-Ex, Paris, France
| | | | | | | | | | - Laurent Mesnard
- UMR702, Paris, France.,Urgences Néphrologiques et Transplantation Rénale, AP-HP, Hôpital Tenon, Paris, France.,Université Pierre et Marie Curie, Paris, France
| | - Eric Daugas
- Université Denis-Diderot, Laboratoire d'excellence INFLAMEX, Paris, France.,UMR1149, Paris, France.,ERL8252, Paris, France.,Departments of Nephrology
| | - François Vrtovsnik
- Université Denis-Diderot, Laboratoire d'excellence INFLAMEX, Paris, France.,UMR1149, Paris, France.,ERL8252, Paris, France.,Departments of Nephrology
| | - Renato C Monteiro
- Université Denis-Diderot, Laboratoire d'excellence INFLAMEX, Paris, France.,UMR1149, Paris, France.,ERL8252, Paris, France.,Immunology, and
| | - Olivier Hermine
- Institut National de la Santé et de la Recherche Médicale Unité Mixte de Recherche (UMR)1163, Paris, France.,Sorbonne Paris Cité, Université René Descartes, Imagine Institute, Paris, France.,Centre National de la Recherche Scientifique Equipe de Recherche Labellisée (ERL)8254, Paris, France.,Laboratoire d'excellence GR-Ex, Paris, France.,Department of Clinical Hematology, AP-HP, Hôpital Necker-Enfants Malades, Paris, France.,Equipe labellisée LIGUE 2015, Paris, France; and
| | - Yelena Z Ginzburg
- Erythropoiesis Laboratory, Lindsey F. Kimball Research Institute, New York Blood Center, New York, New York
| | - Marc Benhamou
- Université Denis-Diderot, Laboratoire d'excellence INFLAMEX, Paris, France.,UMR1149, Paris, France.,ERL8252, Paris, France
| | - Niels O S Camara
- Laboratory of Transplantation Immunobiology, Department of Immunology, Institute of Biomedical Sciences IV, University of São Paulo, Sao Paulo, Brazil
| | - Martin Flamant
- Université Denis-Diderot, Laboratoire d'excellence INFLAMEX, Paris, France.,UMR1149, Paris, France.,ERL8252, Paris, France.,Physiology, Assistance Publique-Hôpitaux de Paris (AP-HP), Hôpital Bichat-Claude Bernard, Paris, France
| | - Ivan C Moura
- Institut National de la Santé et de la Recherche Médicale Unité Mixte de Recherche (UMR)1163, Paris, France; .,Sorbonne Paris Cité, Université René Descartes, Imagine Institute, Paris, France.,Centre National de la Recherche Scientifique Equipe de Recherche Labellisée (ERL)8254, Paris, France.,Laboratoire d'excellence GR-Ex, Paris, France.,Equipe labellisée LIGUE 2015, Paris, France; and
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8
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Sukumaran A, Chang J, Han M, Mintri S, Khaw BA, Kim J. Iron overload exacerbates age-associated cardiac hypertrophy in a mouse model of hemochromatosis. Sci Rep 2017; 7:5756. [PMID: 28720890 PMCID: PMC5516030 DOI: 10.1038/s41598-017-05810-2] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Accepted: 06/02/2017] [Indexed: 12/12/2022] Open
Abstract
Cardiac damage associated with iron overload is the most common cause of morbidity and mortality in patients with hereditary hemochromatosis, but the precise mechanisms leading to disease progression are largely unexplored. Here we investigated the effects of iron overload and age on cardiac hypertrophy using 1-, 5- and 12-month old Hfe-deficient mice, an animal model of hemochromatosis in humans. Cardiac iron levels increased progressively with age, which was exacerbated in Hfe-deficient mice. The heart/body weight ratios were greater in Hfe-deficient mice at 5- and 12-month old, compared with their age-matched wild-type controls. Cardiac hypertrophy in 12-month old Hfe-deficient mice was consistent with decreased alpha myosin and increased beta myosin heavy chains, suggesting an alpha-to-beta conversion with age. This was accompanied by cardiac fibrosis and up-regulation of NFAT-c2, reflecting increased calcineurin/NFAT signaling in myocyte hypertrophy. Moreover, there was an age-dependent increase in the cardiac isoprostane levels in Hfe-deficient mice, indicating elevated oxidative stress. Also, rats fed high-iron diet demonstrated increased heart-to-body weight ratios, alpha myosin heavy chain and cardiac isoprostane levels, suggesting that iron overload promotes oxidative stress and cardiac hypertrophy. Our findings provide a molecular basis for the progression of age-dependent cardiac stress exacerbated by iron overload hemochromatosis.
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Affiliation(s)
- Abitha Sukumaran
- Department of Pharmaceutical Sciences, Northeastern University, Boston, MA, USA
| | - JuOae Chang
- Department of Pharmaceutical Sciences, Northeastern University, Boston, MA, USA
| | - Murui Han
- Department of Pharmaceutical Sciences, Northeastern University, Boston, MA, USA
| | - Shrutika Mintri
- Department of Pharmaceutical Sciences, Northeastern University, Boston, MA, USA
| | - Ban-An Khaw
- Department of Pharmaceutical Sciences, Northeastern University, Boston, MA, USA
| | - Jonghan Kim
- Department of Pharmaceutical Sciences, Northeastern University, Boston, MA, USA.
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9
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Abstract
The regulation of iron metabolism in biological systems centers on providing adequate iron for cellular function while limiting iron toxicity. Because mammals cannot excrete iron, mechanisms have evolved to control iron acquisition, storage, and distribution at both systemic and cellular levels. Hepcidin, the master regulator of iron homeostasis, controls iron flows into plasma through inhibition of the only known mammalian cellular iron exporter ferroportin. Hepcidin is feedback-regulated by iron status and strongly modulated by inflammation and erythropoietic demand. This review highlights recent advances that have changed our understanding of iron metabolism and its regulation.
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Affiliation(s)
- Richard Coffey
- Departments of Medicine and Pathology, David Geffen School of Medicine at UCLA, Los Angeles, California 90095-1690
| | - Tomas Ganz
- Departments of Medicine and Pathology, David Geffen School of Medicine at UCLA, Los Angeles, California 90095-1690.
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10
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Laftah AH, Simpson RJ, Latunde-Dada GO. Intestinal heme absorption in hemochromatosis gene knock-out mice. World J Hematol 2017; 6:17-23. [DOI: 10.5315/wjh.v6.i1.17] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Revised: 11/08/2016] [Accepted: 12/19/2016] [Indexed: 02/05/2023] Open
Abstract
AIM To investigat the influence of hemochromatosis gene (Hfe) mutation on 59Fe labelled duodenal heme absorption in mice.
METHODS Heme absorption was measured in Hfe wild type and Hfe(-/-) mice by the duodenal tied loop and by oral gavage methods. The mRNA expression of heme oxygenase (HO-1), Abcg2 and Flvcr1 genes and levels were determined by quantitative polymerase chain reaction.
RESULTS Heme absorption was significantly increased in homozygous Hfe(-/-) mice despite significant hepatic and splenic iron overload. While duodenal HO-1 mRNA was highly expressed in the wild type and Hfe(-/-) heme-treated group following 24 h heme administration, Flvcr1a mRNA decreased. However, Abcg2 mRNA expression levels in duodenum remained unchanged.
CONCLUSION Heme absorption was enhanced in Hfe(-/-) mice from both duodenal tied-loop segments and by oral gavage methods. HO-1 mRNA levels were enhanced in mice duodenum after 24 h of heme feeding and may account for enhanced heme absorption in Hfe(-/-) mice. Implications for dietary recommendations on heme intake by Hfe subjects to modulate iron loading are important clinical considerations.
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11
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Nadkarni AH, Singh AA, Colaco S, Hariharan P, Colah RB, Ghosh K. Effect of the Hemochromatosis Mutations on Iron Overload among the Indian β Thalassemia Carriers. J Clin Lab Anal 2016; 31. [PMID: 27561698 DOI: 10.1002/jcla.22054] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Accepted: 07/13/2016] [Indexed: 01/07/2023] Open
Abstract
BACKGROUND Hereditary hemochromatosis is a disorder of iron metabolism characterized by increased iron absorption.HFE gene mutations C282Y and H63D are responsible for the majority of hereditary hemochromatosis cases. METHODS We tried to look at the effect of HFE mutations on the iron status. A total of 100 β thalassemia traits (BTT) with 100 normal individuals were screened for the C282Y and H63D mutations using PCR-RFLP. The serum ferritin levels were determined using ELISA kit. RESULTS We did not find the C282Y mutation in our study group. The allelic frequencies for H63D mutation did not differ significantly between β-thalassemia traits (8.5%) and normal controls (9%). ΒΤΤ with H63D genotype of H/D (143.16 ± 80.3 ng/ml) and D/D (504 ng/ml) showed higher ferritin levels as against H/H genotype (88.64 ± 92.43 ng/ml). The statistically significant difference was observed in the mean serum ferritin levels among the individuals showing H/H and D/D genotypes (P < 0.002) and H/D and D/D genotype (P < 0.01) in both the groups. CONCLUSION This suggests that iron load in BTT tends to aggravated with the co-inheritance of the H63D mutation. The mutant H63D gene showed the presence of haplotype 6 which is reported in the European population suggesting a common origin.
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Affiliation(s)
- Anita H Nadkarni
- Department of Haematogenetics, National Institute of Immunohaematology (ICMR), Mumbai, India
| | - Aradhana A Singh
- Department of Haematogenetics, National Institute of Immunohaematology (ICMR), Mumbai, India
| | - Stacy Colaco
- Department of Haematogenetics, National Institute of Immunohaematology (ICMR), Mumbai, India
| | - Priya Hariharan
- Department of Haematogenetics, National Institute of Immunohaematology (ICMR), Mumbai, India
| | - Roshan B Colah
- Department of Haematogenetics, National Institute of Immunohaematology (ICMR), Mumbai, India
| | - Kanjaksha Ghosh
- Surat Raktadan Kendra and Research Center, Udhana - Magdalla Road, Surat, India
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12
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Barton JC, Edwards CQ, Acton RT. HFE gene: Structure, function, mutations, and associated iron abnormalities. Gene 2015; 574:179-92. [PMID: 26456104 PMCID: PMC6660136 DOI: 10.1016/j.gene.2015.10.009] [Citation(s) in RCA: 79] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2015] [Revised: 10/04/2015] [Accepted: 10/06/2015] [Indexed: 01/05/2023]
Abstract
The hemochromatosis gene HFE was discovered in 1996, more than a century after clinical and pathologic manifestations of hemochromatosis were reported. Linked to the major histocompatibility complex (MHC) on chromosome 6p, HFE encodes the MHC class I-like protein HFE that binds beta-2 microglobulin. HFE influences iron absorption by modulating the expression of hepcidin, the main controller of iron metabolism. Common HFE mutations account for ~90% of hemochromatosis phenotypes in whites of western European descent. We review HFE mapping and cloning, structure, promoters and controllers, and coding region mutations, HFE protein structure, cell and tissue expression and function, mouse Hfe knockouts and knockins, and HFE mutations in other mammals with iron overload. We describe the pertinence of HFE and HFE to mechanisms of iron homeostasis, the origin and fixation of HFE polymorphisms in European and other populations, and the genetic and biochemical basis of HFE hemochromatosis and iron overload.
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Affiliation(s)
- James C Barton
- Southern Iron Disorders Center, Birmingham, AL, USA and Department of Medicine; University of Alabama at Birmingham, Birmingham, AL, USA.
| | - Corwin Q Edwards
- Department of Medicine, Intermountain Medical Center and University of Utah, Salt Lake City, UT, USA.
| | - Ronald T Acton
- Southern Iron Disorders Center, Birmingham, AL, USA and Department of Medicine; Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL, USA.
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13
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Jenkitkasemwong S, Wang CY, Coffey R, Zhang W, Chan A, Biel T, Kim JS, Hojyo S, Fukada T, Knutson MD. SLC39A14 Is Required for the Development of Hepatocellular Iron Overload in Murine Models of Hereditary Hemochromatosis. Cell Metab 2015; 22:138-50. [PMID: 26028554 PMCID: PMC4497937 DOI: 10.1016/j.cmet.2015.05.002] [Citation(s) in RCA: 158] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Revised: 03/04/2015] [Accepted: 04/24/2015] [Indexed: 01/07/2023]
Abstract
Nearly all forms of hereditary hemochromatosis are characterized by pathological iron accumulation in the liver, pancreas, and heart. These tissues preferentially load iron because they take up non-transferrin-bound iron (NTBI), which appears in the plasma during iron overload. Yet, how tissues take up NTBI is largely unknown. We report that ablation of Slc39a14, the gene coding for solute carrier SLC39A14 (also called ZIP14), in mice markedly reduced the uptake of plasma NTBI by the liver and pancreas. To test the role of SLC39A14 in tissue iron loading, we crossed Slc39a14(-/-) mice with Hfe(-/-) and Hfe2(-/-) mice, animal models of type 1 and type 2 (juvenile) hemochromatosis, respectively. Slc39a14 deficiency in hemochromatotic mice greatly diminished iron loading of the liver and prevented iron deposition in hepatocytes and pancreatic acinar cells. The data suggest that inhibition of SLC39A14 may mitigate hepatic and pancreatic iron loading and associated pathologies in iron overload disorders.
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Affiliation(s)
- Supak Jenkitkasemwong
- Food Science and Human Nutrition Department, University of Florida, Gainesville, FL 32611, USA
| | - Chia-Yu Wang
- Food Science and Human Nutrition Department, University of Florida, Gainesville, FL 32611, USA
| | - Richard Coffey
- Food Science and Human Nutrition Department, University of Florida, Gainesville, FL 32611, USA
| | - Wei Zhang
- Food Science and Human Nutrition Department, University of Florida, Gainesville, FL 32611, USA
| | - Alan Chan
- Food Science and Human Nutrition Department, University of Florida, Gainesville, FL 32611, USA
| | - Thomas Biel
- Department of Surgery, University of Florida, Gainesville, FL 32611, USA
| | - Jae-Sung Kim
- Department of Surgery, University of Florida, Gainesville, FL 32611, USA
| | - Shintaro Hojyo
- RIKEN Center for Integrative Medical Sciences, Yokohama 230-0045, Japan; Deutsches Rheuma-Forschungszentrum Berlin, Osteoimmunology, Charitéplatz, 10117 Berlin, Germany
| | - Toshiyuki Fukada
- RIKEN Center for Integrative Medical Sciences, Yokohama 230-0045, Japan; Division of Pathology, Department of Oral Diagnostic Sciences, School of Dentistry, Showa University, Shinagawa 142-8666, Japan; Molecular and Cellular Physiology, Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Tokushima 770-8055, Japan
| | - Mitchell D Knutson
- Food Science and Human Nutrition Department, University of Florida, Gainesville, FL 32611, USA.
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Wilson MM, Al-Wakeel H, Said F, El-Ghamrawy M, Assaad M, El-Beshlawy A. Study of the effect of HFE gene mutations on iron overload in Egyptian thalassemia patients. EGYPTIAN JOURNAL OF MEDICAL HUMAN GENETICS 2015. [DOI: 10.1016/j.ejmhg.2015.02.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
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15
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Simcox JA, Mitchell TC, Gao Y, Just SF, Cooksey R, Cox J, Ajioka R, Jones D, Lee SH, King D, Huang J, McClain DA. Dietary iron controls circadian hepatic glucose metabolism through heme synthesis. Diabetes 2015; 64:1108-19. [PMID: 25315005 PMCID: PMC4375081 DOI: 10.2337/db14-0646] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The circadian rhythm of the liver maintains glucose homeostasis, and disruption of this rhythm is associated with type 2 diabetes. Feeding is one factor that sets the circadian clock in peripheral tissues, but relatively little is known about the role of specific dietary components in that regard. We assessed the effects of dietary iron on circadian gluconeogenesis. Dietary iron affects circadian glucose metabolism through heme-mediated regulation of the interaction of nuclear receptor subfamily 1 group d member 1 (Rev-Erbα) with its cosuppressor nuclear receptor corepressor 1 (NCOR). Loss of regulated heme synthesis was achieved by aminolevulinic acid (ALA) treatment of mice or cultured cells to bypass the rate-limiting enzyme in hepatic heme synthesis, ALA synthase 1 (ALAS1). ALA treatment abolishes differences in hepatic glucose production and in the expression of gluconeogenic enzymes seen with variation of dietary iron. The differences among diets are also lost with inhibition of heme synthesis with isonicotinylhydrazine. Dietary iron modulates levels of peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α), a transcriptional activator of ALAS1, to affect hepatic heme. Treatment of mice with the antioxidant N-acetylcysteine diminishes PGC-1α variation observed among the iron diets, suggesting that iron is acting through reactive oxygen species signaling.
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Affiliation(s)
- Judith A Simcox
- Department of Biochemistry, University of Utah, Salt Lake City, UT
| | | | - Yan Gao
- Department of Biochemistry, University of Utah, Salt Lake City, UT
| | - Steven F Just
- Department of Internal Medicine, University of Utah, Salt Lake City, UT
| | - Robert Cooksey
- Veterans Administration Research Service, VA Salt Lake City Health Care System, Salt Lake City, UT
| | - James Cox
- Department of Biochemistry, University of Utah, Salt Lake City, UT
| | - Richard Ajioka
- Department of Biochemistry, University of Utah, Salt Lake City, UT
| | - Deborah Jones
- Department of Internal Medicine, University of Utah, Salt Lake City, UT
| | - Soh-Hyun Lee
- Department of Internal Medicine, University of Utah, Salt Lake City, UT
| | - Daniel King
- Department of Biochemistry, University of Utah, Salt Lake City, UT
| | - Jingyu Huang
- Department of Biochemistry, University of Utah, Salt Lake City, UT
| | - Donald A McClain
- Department of Biochemistry, University of Utah, Salt Lake City, UT Department of Internal Medicine, University of Utah, Salt Lake City, UT Veterans Administration Research Service, VA Salt Lake City Health Care System, Salt Lake City, UT
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16
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Reuben A, Phénix M, Santos MM, Lapointe R. The WT hemochromatosis protein HFE inhibits CD8⁺ T-lymphocyte activation. Eur J Immunol 2014; 44:1604-14. [PMID: 24643698 DOI: 10.1002/eji.201343955] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Revised: 01/21/2014] [Accepted: 02/11/2014] [Indexed: 11/05/2022]
Abstract
MHC class I (MHC I) antigen presentation is a ubiquitous process by which cells present endogenous proteins to CD8(+) T lymphocytes during immune surveillance and response. Hereditary hemochromatosis protein, HFE, is involved in cellular iron uptake but, while structurally homologous to MHC I, is unable to bind peptides. However, increasing evidence suggests a role for HFE in the immune system. Here, we investigated the impact of HFE on CD8(+) T-lymphocyte activation. Using transient HFE transfection assays in a model of APCs, we show that WT HFE (HFEWT ), but not C282Y-mutated HFE, inhibits secretion of MIP-1β from antigen-specific CD8(+) T lymphocytes. HFEWT expression also resulted in major decreases in CD8(+) T-lymphocyte activation as measured by 4-1BB expression. We further demonstrate that inhibition of CD8(+) T-lymphocyte activation was independent of MHC I surface levels, β2-m competition, HFE interaction with transferrin receptor, antigen origin, or epitope affinity. Finally, we identified the α1-2 domains of HFEWT as being responsible for inhibiting CD8(+) T-lymphocyte activation. Our data imply a new role for HFEWT in altering CD8(+) T-lymphocyte reactivity, which could modulate antigen immunogenicity.
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Affiliation(s)
- Alexandre Reuben
- Centre de recherche du Centre hospitalier de l'Université de Montréal (CRCHUM) Institut du cancer de Montréal, Montréal, Québec, Canada; Département de Médecine, Université de Montréal, Montréal, Québec, Canada
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17
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Pelham C, Jimenez T, Rodova M, Rudolph A, Chipps E, Islam MR. Regulation of HFE expression by poly(ADP-ribose) polymerase-1 (PARP1) through an inverted repeat DNA sequence in the distal promoter. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2013; 1829:1257-1265. [PMID: 24184271 DOI: 10.1016/j.bbagrm.2013.10.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2013] [Revised: 09/28/2013] [Accepted: 10/22/2013] [Indexed: 02/08/2023]
Abstract
Hereditary hemochromatosis (HH) is a common autosomal recessive disorder of iron overload among Caucasians of northern European descent. Over 85% of all cases with HH are due to mutations in the hemochromatosis protein (HFE) involved in iron metabolism. Although the importance in iron homeostasis is well recognized, the mechanism of sensing and regulating iron absorption by HFE, especially in the absence of iron response element in its gene, is not fully understood. In this report, we have identified an inverted repeat sequence (ATGGTcttACCTA) within 1700bp (-1675/+35) of the HFE promoter capable to form cruciform structure that binds PARP1 and strongly represses HFE promoter. Knockdown of PARP1 increases HFE mRNA and protein. Similarly, hemin or FeCl3 treatments resulted in increase in HFE expression by reducing nuclear PARP1 pool via its apoptosis induced cleavage, leading to upregulation of the iron regulatory hormone hepcidin mRNA. Thus, PARP1 binding to the inverted repeat sequence on the HFE promoter may serve as a novel iron sensing mechanism as increased iron level can trigger PARP1 cleavage and relief of HFE transcriptional repression.
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Affiliation(s)
- Christopher Pelham
- Biochemistry Laboratory, Northwest Missouri State University, Maryville, MO 64468
| | - Tamara Jimenez
- Biochemistry Laboratory, Northwest Missouri State University, Maryville, MO 64468
| | - Marianna Rodova
- Biochemistry Laboratory, Northwest Missouri State University, Maryville, MO 64468
| | - Angela Rudolph
- Biochemistry Laboratory, Northwest Missouri State University, Maryville, MO 64468
| | - Elizabeth Chipps
- Biochemistry Laboratory, Northwest Missouri State University, Maryville, MO 64468
| | - M Rafiq Islam
- Biochemistry Laboratory, Northwest Missouri State University, Maryville, MO 64468
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18
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Absorption of manganese and iron in a mouse model of hemochromatosis. PLoS One 2013; 8:e64944. [PMID: 23705020 PMCID: PMC3660331 DOI: 10.1371/journal.pone.0064944] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2013] [Accepted: 04/21/2013] [Indexed: 01/01/2023] Open
Abstract
Hereditary hemochromatosis, an iron overload disease associated with excessive intestinal iron absorption, is commonly caused by loss of HFE gene function. Both iron and manganese absorption are regulated by iron status, but the relationships between the transport pathways of these metals and how they are affected by HFE-associated hemochromatosis remain poorly understood. Loss of HFE function is known to alter the intestinal expression of DMT1 (divalent metal transporter-1) and Fpn (ferroportin), transporters that have been implicated in absorption of both iron and manganese. Although the influence of HFE deficiency on dietary iron absorption has been characterized, potential effects on manganese metabolism have yet to be explored. To investigate the role of HFE in manganese absorption, we characterized the uptake and distribution of the metal in Hfe−/− knockout mice after intravenous, intragastric, and intranasal administration of 54Mn. These values were compared to intravenous and intragastric administration of 59Fe. Intestinal absorption of 59Fe was increased and clearance of injected 59Fe was also increased in Hfe−/− mice compared to controls. Hfe−/− mice displayed greater intestinal absorption of 54Mn compared to wild-type Hfe+/+ control mice. After intravenous injection, the distribution of 59Fe to heart and liver was greater in Hfe−/− mice but no remarkable differences were observed for 54Mn. Although olfactory absorption of 54Mn into blood was unchanged in Hfe−/− mice, higher levels of intranasally-instilled 54Mn were associated with Hfe−/− brain compared to controls. These results show that manganese transport and metabolism can be modified by HFE deficiency.
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19
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Hennessy MD, Zak RS, Gay CL, Pullinger CR, Lee KA, Aouizerat BE. Polymorphisms of interleukin-1 Beta and interleukin-17Alpha genes are associated with restless legs syndrome. Biol Res Nurs 2013; 16:143-51. [PMID: 23460603 DOI: 10.1177/1099800413478827] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
OBJECTIVE Dopamine, iron, and inflammatory pathways are considered important to the development of restless legs syndrome (RLS). Recent genetic studies support involvement of dopamine and iron; however, cytokine gene variation in the inflammatory component remains unexplored. A recent study reported a high prevalence of RLS among HIV-infected adults. We estimate occurrence of RLS in an ethnically diverse sample of HIV-infected adults and examine differences in demographic factors, clinical characteristics, and biomarkers relating to dopamine, iron, and inflammation between adults with and without RLS symptoms. DESIGN A prospective longitudinal study aimed at identifying biomarkers of RLS symptom experience among HIV-infected adults. METHOD 316 HIV-positive adults were evaluated using International RLS Study Group criteria. Genes were chosen for hypothesized relationships to dopamine (NOS1, NOS2), iron (HFE) or inflammation-mediated by cytokine genes (interferon [IFN], interleukin [IL], nuclear factor kappa-B [NFKB], and tumor necrosis factor alpha [TNFA]). RESULTS Similar to general population estimates, 11% of the sample met all four RLS diagnostic criteria. Controlling for race, gender, and hemoglobin, carrying two copies of the minor allele for IL1B rs1143643, rs1143634, or rs1143633 or carrying the minor allele for IL17A rs8193036 was associated with increased likelihood of meeting RLS diagnostic criteria. CONCLUSION This study provides preliminary evidence of a genetic association between IL1B and IL17A genes and RLS.
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Affiliation(s)
- Mary Dawn Hennessy
- 1Department of Women, Children, and Family Health Sciences, University of Illinois, Chicago, IL, USA
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20
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Acikyol B, Graham RM, Trinder D, House MJ, Olynyk JK, Scott RJ, Milward EA, Johnstone DM. Brain transcriptome perturbations in the transferrin receptor 2 mutant mouse support the case for brain changes in iron loading disorders, including effects relating to long-term depression and long-term potentiation. Neuroscience 2013; 235:119-28. [PMID: 23333676 DOI: 10.1016/j.neuroscience.2013.01.014] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2012] [Revised: 12/14/2012] [Accepted: 01/02/2013] [Indexed: 11/16/2022]
Abstract
Iron abnormalities within the brain are associated with several rare but severe neurodegenerative conditions. There is growing evidence that more common systemic iron loading disorders such as hemochromatosis can also have important effects on the brain. To identify features that are common across different forms of hemochromatosis, we used microarray and real-time reverse transcription polymerase chain reaction (RT-PCR) to assess brain transcriptome profiles of transferrin receptor 2 mutant mice (Tfr2(mut)), a model of a rare type of hereditary hemochromatosis, relative to wildtype control mice. The results were compared with our previous findings in dietary iron-supplemented wildtype mice and Hfe(-/-) mice, a model of a common type of hereditary hemochromatosis. For transcripts showing significant changes relative to controls across all three models, there was perfect (100%) directional concordance (i.e. transcripts were increased in all models or decreased in all models). Comparison of the two models of hereditary hemochromatosis, which showed more pronounced changes than the dietary iron-supplemented mice, revealed numerous common molecular effects. Pathway analyses highlighted changes for genes relating to long-term depression (6.8-fold enrichment, p=5.4×10(-7)) and, to a lesser extent, long-term potentiation (3.7-fold enrichment, p=0.01), with generalized reductions in transcription of key genes from these pathways, which are involved in modulating synaptic strength and efficacy and are essential for memory and learning. The agreement across the models suggests the findings are robust and strengthens previous evidence that iron loading disorders affect the brain. Perturbations of brain phenomena such as long-term depression and long-term potentiation might partly explain neurologic symptoms reported for some hemochromatosis patients.
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Affiliation(s)
- B Acikyol
- School of Biomedical Sciences and Pharmacy, The University of Newcastle, Callaghan, NSW, Australia
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21
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Masaratana P, Latunde-Dada GO, Patel N, Simpson RJ, Vaulont S, McKie AT. Iron metabolism in hepcidin1 knockout mice in response to phenylhydrazine-induced hemolysis. Blood Cells Mol Dis 2012; 49:85-91. [PMID: 22609087 DOI: 10.1016/j.bcmd.2012.04.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2012] [Accepted: 03/27/2012] [Indexed: 11/26/2022]
Abstract
Hepcidin, an iron regulatory peptide, plays a central role in the maintenance of systemic iron homeostasis by inducing the internalization and degradation of the iron exporter, ferroportin. Hepcidin expression in the liver is regulated in response to several stimuli including iron status, erythropoietic activity, hypoxia and inflammation. Hepcidin expression has been shown to be reduced in phenylhydrazine-treated mice, a mouse model of acute hemolysis. In this mouse model, hepcidin suppression was associated with increased expression of molecules involved in iron transport and recycling. The present study aims to explore whether the response to phenylhydrazine treatment is affected by hepcidin deficiency and/or the subsequently altered iron metabolism. Hepcidin1 knockout (Hamp(-/-)) and wild type mice were treated with phenylhydrazine or saline and parameters of iron homeostasis were determined 3 days after the treatment. In wild type mice, phenylhydrazine administration resulted in significantly reduced serum iron, increased tissue non-heme iron levels and suppressed hepcidin expression. The treatment was also associated with increases in membrane ferroportin protein levels and spleen heme oxygenase 1 mRNA expression. In addition, trends toward increased mRNA expression of duodenal iron transporters were also observed. In contrast, serum iron and tissue non-heme iron levels in Hamp(-/-) mice were unaffected by the treatment. Moreover, the effects of phenylhydrazine on the expression of ferroportin and duodenal iron transporters were not observed in Hamp(-/-) mice. Interestingly, mRNA levels of molecules involved in splenic heme uptake and degradation were significantly induced by Hamp disruption. In summary, our study demonstrates that the response to phenylhydrazine-induced hemolysis differs between wild type and Hamp(-/-) mice. This observation may be caused by the absence of hepcidin per se or the altered iron homeostasis induced by the lack of hepcidin in these mice.
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Affiliation(s)
- Patarabutr Masaratana
- Diabetes and Nutritional Sciences Division, School of Medicine, King's College London, 150 Stamford Street, London SE1 9NH, UK
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22
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Abstract
Murine models have made valuable contributions to our understanding of iron metabolism. Investigation of mice with inherited forms of anemia has led to the discovery of novel proteins involved in iron homeostasis. A growing number of murine models are being developed to investigate mitochondrial iron metabolism. Mouse strains are available for the major forms of hereditary hemochromatosis. Findings in murine models support the concept that the pathogenesis of nearly all forms of hereditary hemochromatosis involves inappropriately low expression of hepcidin. The availability of mice with floxed iron-related genes allows the study of the in vivo consequences of cell-selective deletion of these genes.
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Affiliation(s)
- Robert E Fleming
- Departments of Pediatrics and Biochemistry & Molecular Biology, Saint Louis University School of Medicine, St. Louis, MO 63104, USA.
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23
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Mutation of the gastric hydrogen-potassium ATPase alpha subunit causes iron-deficiency anemia in mice. Blood 2011; 118:6418-25. [PMID: 21976678 DOI: 10.1182/blood-2011-04-350082] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Iron is an essential component of heme and hemoglobin, and therefore restriction of iron availability directly limits erythropoiesis. In the present study, we report a defect in iron absorption that results in iron-deficiency anemia, as revealed by an N-ethyl-N-nitrosourea-induced mouse phenotype called sublytic. Homozygous sublytic mice develop hypochromic microcytic anemia with reduced osmotic fragility of RBCs. The sublytic phenotype stems from impaired gastrointestinal iron absorption caused by a point mutation of the gastric hydrogen-potassium ATPase α subunit encoded by Atp4a, which results in achlorhydria. The anemia of sublytic homozygotes can be corrected by feeding with a high-iron diet or by parenteral injection of iron dextran; rescue can also be achieved by providing acidified drinking water to sublytic homozygotes. These findings establish the necessity of the gastric proton pump for iron absorption and effective erythropoiesis.
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Association between HFE polymorphisms and susceptibility to Alzheimer's disease: a meta-analysis of 22 studies including 4,365 cases and 8,652 controls. Mol Biol Rep 2011; 39:3089-95. [PMID: 21701828 DOI: 10.1007/s11033-011-1072-z] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2011] [Accepted: 06/10/2011] [Indexed: 01/27/2023]
Abstract
Whether the variations in the hemochromatosis (HFE) gene increase Alzheimer's disease (AD) risk is still undetermined. We performed a meta-analysis in order to systematically summarize the possible association. Studies were identified by searching PUBMED, Web of Science and EMBASE databases complemented with screening the references of the retrieved studies. The association was measured using random-effect or fixed-effect odds ratio (OR) combined with 95% confidence intervals (CIs) according to the studies' heterogeneity. For C282Y polymorphism, we did not find any association using data from 22 studies including 4,365 cases and 8,652 controls. For H63D polymorphism, on the basis of 2,795 cases and 7,424 controls from 17 studies, we observed a significant association (allele contrast: OR = 0.902, 95% CI = 0.819-0.994, P = 0.037; minor-allele-dominant model: OR = 0.887, 95% CI = 0.790-0.996, P = 0.043). No publication bias was detected in this meta-analysis. The synthesis of available evidence supports mutant of HFE H63D polymorphism plays a protective role for AD risk.
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25
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Brown DE, McCoy MW, Pilonieta MC, Nix RN, Detweiler CS. Chronic murine typhoid fever is a natural model of secondary hemophagocytic lymphohistiocytosis. PLoS One 2010; 5:e9441. [PMID: 20195482 PMCID: PMC2829187 DOI: 10.1371/journal.pone.0009441] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2010] [Accepted: 02/09/2010] [Indexed: 12/27/2022] Open
Abstract
Hemophagocytic lymphohistiocytosis (HLH) is a hyper-inflammatory clinical syndrome associated with neoplastic disorders especially lymphoma, autoimmune conditions, and infectious agents including bacteria, viruses, protozoa and fungi. In both human and veterinary medicine, hemophagocytic histiocytic disorders are clinically important and frequently fatal. HLH in humans can be a primary (familial, autosomal recessive) or secondary (acquired) condition, with both types generally precipitated by an infectious agent. Previously, no mouse model for secondary HLH has been reported. Using Salmonella enterica serotype Typhimurium by oral gavage to mimic naturally-occurring infection in Sv129S6 mice, we characterized the clinical, hematologic and morphologic host responses to disease thereby describing an animal model with the clinico-pathologic features of secondary HLH as set forth by the Histiocyte Society: fever, splenomegaly, cytopenias (anemia, thrombocytopenia), hemophagocytosis in bone marrow and spleen, hyperferritinemia, and hypofibrinogenemia. Disease severity correlates with high splenic and hepatic bacterial load, and we show disease course can be monitored and tracked in live animals. Whereby secondary HLH is known to occur in human patients with typhoid fever and other infectious diseases, our characterization of a viable natural disease model of secondary HLH offers an important means to elucidate pathogenesis of poorly understood mechanisms of secondary HLH and investigation of novel therapies. We characterize previously unreported secondary HLH in a chronic mouse model of typhoid fever, and novel changes in hematology including decreased tissue ferric iron storage that differs from classically described anemia of chronic disease. Our studies demonstrate S. Typhimurium infection of mice is a natural infectious disease model of secondary HLH that may have utility for elucidating disease pathogenesis and developing novel therapies.
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Affiliation(s)
- Diane E. Brown
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, Colorado, United States of America
- Paleontology Section, Museum of Natural History, University of Colorado, Boulder, Colorado, United States of America
- * E-mail: (DEB); (CSD)
| | - Melissa W. McCoy
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, Colorado, United States of America
| | - M. Carolina Pilonieta
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, Colorado, United States of America
| | - Rebecca N. Nix
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, Colorado, United States of America
| | - Corrella S. Detweiler
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, Colorado, United States of America
- * E-mail: (DEB); (CSD)
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BMP/Smad signaling is not enhanced in Hfe-deficient mice despite increased Bmp6 expression. Blood 2009; 114:2515-20. [PMID: 19622835 DOI: 10.1182/blood-2009-02-206771] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Impaired regulation of hepcidin expression in response to iron loading appears to be the pathogenic mechanism for hereditary hemochromatosis. Iron normally induces expression of the BMP6 ligand, which, in turn, activates the BMP/Smad signaling cascade directing hepcidin expression. The molecular function of the HFE protein, involved in the most common form of hereditary hemochromatosis, is still unknown. We have used Hfe-deficient mice of different genetic backgrounds to test whether HFE has a role in the signaling cascade induced by BMP6. At 7 weeks of age, these mice have accumulated iron in their liver and have increased Bmp6 mRNA and protein. However, in contrast to mice with secondary iron overload, levels of phosphorylated Smads 1/5/8 and of Id1 mRNA, both indicators of BMP signaling, are not significantly higher in the liver of these mice than in wild-type livers. As a consequence, hepcidin mRNA levels in Hfe-deficient mice are similar or marginally reduced, compared with 7-week-old wild-type mice. The inappropriately low levels of Id1 and hepcidin mRNA observed at weaning further suggest that Hfe deficiency triggers iron overload by impairing hepatic Bmp/Smad signaling. HFE therefore appears to facilitate signal transduction induced by the BMP6 ligand.
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Schmidt PJ, Toran PT, Giannetti AM, Bjorkman PJ, Andrews NC. The transferrin receptor modulates Hfe-dependent regulation of hepcidin expression. Cell Metab 2008; 7:205-14. [PMID: 18316026 PMCID: PMC2292811 DOI: 10.1016/j.cmet.2007.11.016] [Citation(s) in RCA: 253] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/03/2007] [Revised: 11/10/2007] [Accepted: 11/30/2007] [Indexed: 12/21/2022]
Abstract
Hemochromatosis is caused by mutations in HFE, a protein that competes with transferrin (TF) for binding to transferrin receptor 1 (TFR1). We developed mutant mouse strains to gain insight into the role of the Hfe/Tfr1 complex in regulating iron homeostasis. We introduced mutations into a ubiquitously expressed Tfr1 transgene or the endogenous Tfr1 locus to promote or prevent the Hfe/Tfr1 interaction. Under conditions favoring a constitutive Hfe/Tfr1 interaction, mice developed iron overload attributable to inappropriately low expression of the hormone hepcidin. In contrast, mice carrying a mutation that interferes with the Hfe/Tfr1 interaction developed iron deficiency associated with inappropriately high hepcidin expression. High-level expression of a liver-specific Hfe transgene in Hfe-/- mice was also associated with increased hepcidin production and iron deficiency. Together, these models suggest that Hfe induces hepcidin expression when it is not in complex with Tfr1.
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Affiliation(s)
- Paul J Schmidt
- Division of Hematology/Oncology, Children's Hospital Boston, Boston, MA 02115, USA
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28
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Chua ACG, Graham RM, Trinder D, Olynyk JK. The regulation of cellular iron metabolism. Crit Rev Clin Lab Sci 2008; 44:413-59. [PMID: 17943492 DOI: 10.1080/10408360701428257] [Citation(s) in RCA: 109] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
While iron is an essential trace element required by nearly all living organisms, deficiencies or excesses can lead to pathological conditions such as iron deficiency anemia or hemochromatosis, respectively. A decade has passed since the discovery of the hemochromatosis gene, HFE, and our understanding of hereditary hemochromatosis (HH) and iron metabolism in health and a variety of diseases has progressed considerably. Although HFE-related hemochromatosis is the most widespread, other forms of HH have subsequently been identified. These forms are not attributed to mutations in the HFE gene but rather to mutations in genes involved in the transport, storage, and regulation of iron. This review is an overview of cellular iron metabolism and regulation, describing the function of key proteins involved in these processes, with particular emphasis on the liver's role in iron homeostasis, as it is the main target of iron deposition in pathological iron overload. Current knowledge on their roles in maintaining iron homeostasis and how their dysregulation leads to the pathogenesis of HH are discussed.
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Affiliation(s)
- Anita C G Chua
- School of Medicine and Pharmacology, University of Western Australia, Fremantle, Western Australia, Australia
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29
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Abstract
Iron is a micronutrient that is an essential component that drives many metabolic reactions. Too little iron leads to anemia and too much iron increases the oxidative stress of body tissues leading to inflammation, cell death, and system organ dysfunction, including cancer. Maintaining normal iron balance is achieved by rigorous control of the amount absorbed by the intestine, that released from macrophages following erythrophagocytosis of effete red cells and by either release or uptake from hepatocytes. Hepcidin is a recently characterized molecule that appears to play a key role in the regulation of iron efflux from enterocytes, macrophages, and hepatocytes. It is produced by hepatocytes under basal conditions, in response to alterations in increased iron stores or reduced requirement for erythropoiesis and by inflammation. The proteins that regulate hepcidin expression are presently being defined, albeit that our present understanding is still far from complete. This review focuses on the molecules which regulate hepcidin expression. The subsequent characterization of these proteins using molecular, cellular, and physiological approaches also is discussed along with inflammatory signals and receptors involved in hepcidin expression.
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Affiliation(s)
- Phillip S Oates
- Physiology M311, School of Biomedical, Biomolecular and Chemical Sciences, University of Western Australia, Western Australia, Australia.
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30
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Ajioka RS, LeBoeuf RC, Gillespie RR, Amon LM, Kushner JP. Mapping genes responsible for strain-specific iron phenotypes in murine chromosome substitution strains. Blood Cells Mol Dis 2007; 39:199-205. [PMID: 17493847 PMCID: PMC2703004 DOI: 10.1016/j.bcmd.2007.03.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2007] [Accepted: 03/24/2007] [Indexed: 11/16/2022]
Abstract
The highly variable clinical phenotype observed in patients homozygous for the C282Y mutation of the hereditary hemochromatosis gene (HFE) is likely due to the influence of non-HFE modifier genes. The primary functional abnormality causing iron overload in hemochromatosis is hyper-absorption of dietary iron. We found that iron absorption in inbred mice varies in a strain-specific manner, as does the pattern of iron distribution to the liver and spleen. A/J mice absorbed approximately twice the amount of 59Fe delivered by gavage compared to the C57BL/6 strain. Genetic comparisons between A/J and C57BL/6 were facilitated by the availability of consomic chromosome substitution strains (CSS). Each CSS has an individual chromosome pair from A/J on an otherwise C57BL/6J background. We found that iron absorption and iron content in liver and in spleen were continuous variables suggesting that each trait is under multigenic control. No trait co-segregated among the CSS. Chromosome 5 from A/J, however, imparted the highest iron absorption phenotype and multiple CSS had absorption levels equivalent to A/J. Chromosomes 9 and X were associated with high spleen iron content. These data suggest that multiple genes contribute to the regulation of iron absorption and that individual organ iron phenotypes are independently regulated.
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Affiliation(s)
- Richard S Ajioka
- Division of Hematology, Department of Internal Medicine, University of Utah School of Medicine, Salt Lake City, UT 84132, USA.
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31
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Constante M, Wang D, Raymond VA, Bilodeau M, Santos MM. Repression of repulsive guidance molecule C during inflammation is independent of Hfe and involves tumor necrosis factor-alpha. THE AMERICAN JOURNAL OF PATHOLOGY 2007; 170:497-504. [PMID: 17255318 PMCID: PMC1851854 DOI: 10.2353/ajpath.2007.060437] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Genetic iron overload, or hemochromatosis, can be caused by mutations in HFE, hemojuvelin, and hepcidin genes. Hepcidin, a negative regulator of intestinal iron absorption, is found to be inappropriately low in both patients and in animal models, indicating that proper control of basal hepcidin levels requires both hemojuvelin and HFE. In mice, repulsive guidance molecule c (Rgmc, the hemojuvelin mouse ortholog) and hepcidin levels are transcriptionally regulated during inflammation. Here, we report that basal Rgmc levels in Hfe-deficient mice are normal and that these mice retain the ability to suppress Rgmc expression after lipopolysaccharide (LPS) challenge. Thus, Rgmc regulation by LPS is Hfe-independent. The response of Rgmc to LPS involves signaling through toll-like receptor 4 (Tlr4), because Tlr4-deficient mice do not show altered Rgmc expression after LPS administration. We further show that tumor necrosis factor-alpha, but not interleukin-6, is sufficient to cause Rgmc down-regulation by LPS. These results contrast with previous data demonstrating that hepcidin levels are directly regulated by interleukin-6 but not by tumor necrosis factor-alpha. The regulation of iron-related genes by different cytokines may allow for time-dependent control of iron metabolism changes during inflammation and may be relevant to chronic inflammation, infections, and cancer settings, leading to the development of anemia of chronic disease.
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Affiliation(s)
- Marco Constante
- Centre de Recherche, Centre Hospitalier de l'Université de Montréal, Québec, Canada
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32
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Gouya L, Muzeau F, Robreau AM, Letteron P, Couchi E, Lyoumi S, Deybach JC, Puy H, Fleming R, Demant P, Beaumont C, Grandchamp B. Genetic study of variation in normal mouse iron homeostasis reveals ceruloplasmin as an HFE-hemochromatosis modifier gene. Gastroenterology 2007; 132:679-86. [PMID: 17258727 DOI: 10.1053/j.gastro.2006.11.024] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2006] [Accepted: 11/02/2006] [Indexed: 01/10/2023]
Abstract
BACKGROUND & AIMS Genetic hemochromatosis is one of the most common genetic disorders, with progressive tissue iron overload leading to severe clinical complications. In Northern European populations, genetic hemochromatosis is usually caused by homozygosity for the C282Y mutation in the HFE protein. However, penetrance of this mutation is incomplete, suggesting that other genetic and environmental factors contribute to its differential biologic or clinical expression. METHODS To identify genes modifying iron homeostasis, we screened the 27 recombinant congenic strains of the C3H/DiSnA-C57BL/10ScSnA/Dem series for tissue and serum iron indices and genotyped 18 microsatellite markers in (C3H/DiSnA x HcB-2) F2 hybrid mice. RESULTS We identified 1 locus encompassing the Ceruloplasmin (Cp) gene with a strong linkage with liver iron, serum iron, and transferrin levels but not with spleen iron. Sequencing of Cp showed an R435X nonsense mutation in exon 7 in C3H/DiSnA mice. To evaluate whether Cp might act as a modifier gene of genetic hemochromatosis, we intercrossed C3H Hfe(-/-) and C3HDiSnA Cp(R435X/R435X) mice. As expected, we found that double-mutant mice deposited more iron in the liver than mice defective for either one or both genes. In contrast, Hfe(-/-) x Cp(R435/R435X) or Cp(R435X/R435X) x Hfe(+/-) showed 30% decrease in liver iron when compared with single mutant mice. CONCLUSIONS This study highlights the existence of complex interactions between Cp and HFE and represents the first example of a modifier gene with a protective effect, in which heterozygosity reduces the iron load in the context of HFE deficiency.
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Affiliation(s)
- Laurent Gouya
- INSERM U773, Centre de Recherche Biomédicale Bichat Beaujon CRB3, Université Paris 7 Denis Diderot, site Bichat, Paris, France
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33
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Drake SF, Morgan EH, Herbison CE, Delima R, Graham RM, Chua ACG, Leedman PJ, Fleming RE, Bacon BR, Olynyk JK, Trinder D. Iron absorption and hepatic iron uptake are increased in a transferrin receptor 2 (Y245X) mutant mouse model of hemochromatosis type 3. Am J Physiol Gastrointest Liver Physiol 2007; 292:G323-8. [PMID: 16935854 DOI: 10.1152/ajpgi.00278.2006] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Hereditary hemochromatosis type 3 is an iron (Fe)-overload disorder caused by mutations in transferrin receptor 2 (TfR2). TfR2 is expressed highly in the liver and regulates Fe metabolism. The aim of this study was to investigate duodenal Fe absorption and hepatic Fe uptake in a TfR2 (Y245X) mutant mouse model of hereditary hemochromatosis type 3. Duodenal Fe absorption and hepatic Fe uptake were measured in vivo by 59Fe-labeled ascorbate in TfR2 mutant mice, wild-type mice, and Fe-loaded wild-type mice (2% dietary carbonyl Fe). Gene expression was measured by real-time RT-PCR. Liver nonheme Fe concentration increased progressively with age in TfR2 mutant mice compared with wild-type mice. Fe absorption (both duodenal Fe uptake and transfer) was increased in TfR2 mutant mice compared with wild-type mice. Likewise, expression of genes participating in duodenal Fe uptake (Dcytb, DMT1) and transfer (ferroportin) were increased in TfR2 mutant mice. Nearly all of the absorbed Fe was taken up rapidly by the liver. Despite hepatic Fe loading, hepcidin expression was decreased in TfR2 mutant mice compared with wild-type mice. Even when compared with Fe-loaded wild-type mice, TfR2 mutant mice had increased Fe absorption, increased duodenal Fe transport gene expression, increased liver Fe uptake, and decreased liver hepcidin expression. In conclusion, despite systemic Fe loading, Fe absorption and liver Fe uptake were increased in TfR2 mutant mice in association with decreased expression of hepcidin. These findings support a model in which TfR2 is a sensor of Fe status and regulates duodenal Fe absorption and liver Fe uptake.
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Affiliation(s)
- S F Drake
- School of Medicine and Pharmacology, Fremantle Hospital, University of Western Australia, PO Box 480, Fremantle, 6959, WA, Australia
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34
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Constante M, Jiang W, Wang D, Raymond VA, Bilodeau M, Santos MM. Distinct requirements for Hfe in basal and induced hepcidin levels in iron overload and inflammation. Am J Physiol Gastrointest Liver Physiol 2006; 291:G229-37. [PMID: 16565419 PMCID: PMC2891007 DOI: 10.1152/ajpgi.00092.2006] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Hepcidin is a negative regulator of iron absorption produced mainly by the liver in response to changes in iron stores and inflammation, and its levels have been shown to regulate the intestinal basolateral iron transporter ferroportin1 (Fp1). Hereditary hemochromatosis patients and Hfe-deficient mice show inappropriate expression of hepcidin but, in apparent contradiction, still retain the ability to regulate iron absorption in response to alterations of iron metabolism. To further understand the molecular relationships among Hfe, hepcidin, and Fp1, we investigated hepcidin and Fp1 regulation in Hfe-deficient mice (Hfe-/- and beta2m-/-) in response to iron deprivation, iron loading, and acute inflammation. We found that whereas basal hepcidin levels were manifestly dependent on the presence of Hfe and on the mouse background, all Hfe-deficient mice were still able to regulate hepcidin in situations of altered iron homeostasis. In the liver, Fp1 was modulated in opposite directions by iron and LPS, and its regulation in Hfe-deficient mice was similar to that observed in wild-type mice. In addition, we found that iron-deprived mice were able to mount a robust response after LPS challenge and that Toll-like receptor 4 (TLR-4)-deficient mice fail to regulate hepcidin expression in response to LPS. In conclusion, these results suggest that although Hfe is necessary for the establishment of hepcidin basal levels, it is dispensable for hepcidin regulation through both the iron-sensing and inflammatory pathways, and hepatic Fp1 regulation is largely independent of hepcidin and Hfe. The inflammatory pathway overrides the iron-sensing pathway and is TLR-4 dependent.
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Affiliation(s)
- Marco Constante
- Centre de recherche, Centre hospitalier de l'Université de Montréal, Hôpital Notre-Dame, Canada
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35
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Lao BJ, Kamei DT. A compartmental model of iron regulation in the mouse. J Theor Biol 2006; 243:542-54. [PMID: 16935308 DOI: 10.1016/j.jtbi.2006.06.033] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2006] [Revised: 06/06/2006] [Accepted: 06/16/2006] [Indexed: 11/27/2022]
Abstract
A simple compartmental model is developed for investigating the mechanism of iron homeostasis. In contrast to previous mathematical models of iron metabolism, the liver is included as a key site of iron regulation. Compartments for free iron in blood, diferric transferrin (Tf) in blood, hepatocytes, red blood cells, and macrophages are included, and their roles in iron regulation are explored. The function of hepcidin in regulating iron absorption is modeled through an inverse relationship between hepatocyte transferrin receptor 2 (TfR2) levels and the rate of iron export processes mediated by ferroportin (Fpn). Simulations of anemia and erythropoiesis stimulation support the idea that the iron demands of the erythroid compartment can be communicated through diferric Tf. The iron-responsive element of Fpn is found to be important for stabilizing intracellular iron stores in response to changing iron demands and allowing proper iron regulation through diferric Tf. The contribution of iron dysregulation to the pathogenesis of iron overload disorders is also investigated. It is shown that the characteristics of HFE hemochromatosis can be reproduced by increasing the setpoint of iron absorption in the duodenum to a level where the system cannot downregulate iron absorption to meet the iron excretion rate.
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Affiliation(s)
- Bert J Lao
- Department of Bioengineering, University of California, Los Angeles, CA 90095, USA
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36
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Lesbordes-Brion JC, Viatte L, Bennoun M, Lou DQ, Ramey G, Houbron C, Hamard G, Kahn A, Vaulont S. Targeted disruption of the hepcidin 1 gene results in severe hemochromatosis. Blood 2006; 108:1402-5. [PMID: 16574947 DOI: 10.1182/blood-2006-02-003376] [Citation(s) in RCA: 185] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
We previously reported that mice made deficient for the transcriptional factor USF2 fail to express hepcidin 1 and hepcidin 2 genes as a consequence of targeted disruption of the Usf2 gene lying just upstream in the locus. These mice developed an iron overload phenotype with excess iron deposition in parenchymal cells and decreased reticuloendothelial iron. At that time, although the role of USF2 was still confounding, we proposed for the first time the role of hepcidin as a negative regulator of iron absorption and iron release from macrophages. Accordingly, we subsequently demonstrated that hyperexpression of hepcidin 1, but not hepcidin 2, resulted in a profound hyposideremic anemia. To analyze the consequences of hepcidin 1 deletion on iron metabolism without any disturbance due to USF2 deficiency, we disrupted the hepcidin 1 gene by targeting almost all the coding region. Confirming our prior results, Hepc1(-/-) mice developed early and severe multivisceral iron overload, with sparing of the spleen macrophages, and demonstrated increased serum iron and ferritin levels as compared with their controls.
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Affiliation(s)
- Jeanne-Claire Lesbordes-Brion
- Institut Cochin, Département de Génétique, Développement et Pathologie Moléculaire, Institut National de la Santé et de la Recherche Médicale U567, Paris, France
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37
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Franke SIR, Prá D, Giulian R, Dias JF, Yoneama ML, da Silva J, Erdtmann B, Henriques JAP. Influence of orange juice in the levels and in the genotoxicity of iron and copper. Food Chem Toxicol 2006; 44:425-35. [PMID: 16263202 DOI: 10.1016/j.fct.2005.08.016] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2004] [Revised: 08/04/2005] [Accepted: 08/18/2005] [Indexed: 11/18/2022]
Abstract
World consumption of natural juices is increasing as a consequence of the human search for a healthier life. The juice production industry, especially for orange juice, is expanding in several countries and particularly in Brazil. Despite scientific data reporting beneficial properties derived from juice consumption, some components of juices have been identified as mutagenic or carcinogenic. Carcinogenic or genotoxic effects may be mediated by the interaction of juice components with transition metals or by sub-products of juice auto-oxidation. In this study, the mutagenic potential of orange juice and two metallic agents used in dietary supplementation, FeSO(4) and CuSO(4), were investigated using the comet assay in mouse blood cells (in vivo). Both metal compounds were genotoxic for eukaryotic cells after 24h treatment at the doses used. Significant damage repair was observed after 48h of treatment with the same compounds. Orange juice had a modulating effect on the action of metallic sulfates. In the case of iron treatment, the presence of the orange juice had a preventive, but not restorative, effect. On the other hand, in the case of copper treatment, the effects were both preventive and restorative. PIXE (particle induced X-ray emission) analysis indicated a positive correlation between DNA damage and the hepatic levels of iron and a negative correlation between whole blood copper and DNA damage. A negative correlation between hepatic iron and whole blood copper content was also seen in the treatment with both ferrous and cupric sulfates.
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Affiliation(s)
- Silvia Isabel Rech Franke
- Curso de Nutrição, Departamento de Educação Física e Saúde, Universidade de Santa Cruz do Sul, UNISC, RS, Brazil
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38
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Adams BD, Lazova R, Andrews NC, Milstone LM. Iron in skin of mice with three etiologies of systemic iron overload. J Invest Dermatol 2006; 125:1200-5. [PMID: 16354190 PMCID: PMC2243217 DOI: 10.1111/j.0022-202x.2005.23949.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In human hemochromatosis, tissue toxicity is a function of tissue iron levels. Despite reports of skin toxicity in hemochromatosis, little is known about iron levels in skin of individuals with systemic iron overload. We measured skin iron and studied skin histology in three mouse models of systemic iron overload: mice with a deletion of the hemochromatosis (Hfe) gene, mice fed a high iron diet, and mice given parenteral injections of iron. In Hfe(-/-) mice, iron content in the epidermis and dermis was unexpectedly the same as in Hfe(+/+) mice, and there were no histological abnormalities detected after 30 wk. A high iron diet produced increased iron in the epidermis of both normal and Hfe(-/-) animals; a high diet increased iron in the dermis only in Hfe(-/-) mice. Increased skin iron was not associated with other histological changes, even after 19 wk. Parenteral administration of iron produced increased iron in the epidermis and dermis, and gave the skin a bronze hue. These results show that the amount and distribution of iron in the skin depends on the etiology of iron overload. It appears that neither Hfe deletion nor elevated skin iron alone can account for cutaneous manifestations reportedly seen in humans with hereditary hemochromatosis.
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Affiliation(s)
- Brian D. Adams
- Department of Dermatology, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Rossitza Lazova
- Department of Dermatology, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Nancy C. Andrews
- †Division of Hematology/Oncology, Children's Hospital, Harvard Medical School and Howard Hughes Medical Institute, Boston, Massachusetts, USA
| | - Leonard M. Milstone
- Department of Dermatology, Yale University School of Medicine, New Haven, Connecticut, USA
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39
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Cherukuri S, Potla R, Sarkar J, Nurko S, Harris ZL, Fox PL. Unexpected role of ceruloplasmin in intestinal iron absorption. Cell Metab 2005; 2:309-19. [PMID: 16271531 DOI: 10.1016/j.cmet.2005.10.003] [Citation(s) in RCA: 123] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/20/2005] [Revised: 07/10/2005] [Accepted: 10/12/2005] [Indexed: 02/07/2023]
Abstract
Ferroxidases are essential for normal iron homeostasis in most organisms. The paralogous vertebrate ferroxidases ceruloplasmin (Cp) and hephaestin (Heph) are considered to have nonidentical functions in iron transport: plasma Cp drives iron transport from tissue stores while intestinal Heph facilitates iron absorption from the intestinal lumen. To clarify the function of Cp, we acutely bled Cp-/- mice to stress iron homeostasis pathways. Red cell hemoglobin recovery was defective in stressed Cp-/- mice, consistent with low iron availability. Contrary to expectations, iron was freely released from spleen and liver stores in Cp-/- mice, but intestinal iron absorption was markedly impaired. Phlebotomy of wild-type mice caused a striking shift of Cp from the duodenal epithelium to the underlying lamina propria, suggesting a critical function of Cp in basolateral iron transport. Regulated relocalization of intestinal Cp may represent a fail-safe mechanism in which Cp shares with Heph responsibility for iron absorption under stress.
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Affiliation(s)
- Srujana Cherukuri
- Department of Cell Biology, The Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, Ohio 44195, USA
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40
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Abstract
Our knowledge of how the body absorbs iron from the diet and how this process is controlled has increased at a rapid rate in recent years. The identification of key molecules, including the iron regulatory peptide hepcidin, and the analysis of how they are regulated and interact have led to the development of an integrated model for the control of iron absorption by body iron requirements. Research now focuses on the role of the liver as the primary regulator of iron absorption, and this review considers some of the recent highlights and controversies in this area.
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Affiliation(s)
- David M Frazer
- Iron Metabolism Laboratory, Queensland Institute of Medical Research, PO Royal Brisbane Hospital, Brisbane, Queensland 4029, Australia
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41
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Ludwiczek S, Theurl I, Bahram S, Schümann K, Weiss G. Regulatory networks for the control of body iron homeostasis and their dysregulation in HFE mediated hemochromatosis. J Cell Physiol 2005; 204:489-99. [PMID: 15744772 DOI: 10.1002/jcp.20315] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Although the recent identification of several genes has extended our knowledge on the maintenance of body iron homeostasis, their tissue specific expression patterns and the underlying regulatory networks are poorly understood. We studied C57black/Sv129 mice and HFE knockout (HFE -/-) variants thereof as a model for hemochromatosis, and investigated the expression of iron metabolism genes in the duodenum, liver, and kidney as a function of dietary iron challenge. In HFE +/+ mice dietary iron supplementation increased hepatic expression of hepcidin which was paralleled by decreased iron regulatory protein (IRP) activity, and reduced expression of divalent metal transporter-1 (DMT-1) and duodenal cytochrome b (Dcytb) in the enterocyte. In HFE -/- mice hepcidin formation was diminished upon iron challenge which was associated with decreased hepatic transferrin receptor (TfR)-2 levels. Accordingly, HFE -/- mice presented with high duodenal Dcytb and DMT-1 levels, and increased IRP and TfR expression, suggesting iron deficiency in the enterocyte and increased iron absorption. In parallel, HFE -/- resulted in reduced renal expression of Dcytb and DMT-1. Our data suggest that the feed back regulation of duodenal iron absorption by hepcidin is impaired in HFE -/- mice, a model for genetic hemochromatosis. This change may be linked to inappropriate iron sensing by the liver based on decreased TfR-2 expression, resulting in reduced circulating hepcidin levels and an inappropriate up-regulation of Dcytb and DMT-1 driven iron absorption. In addition, iron excretion/reabsorption by the kidneys may be altered, which may aggravate progressive iron overload.
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Affiliation(s)
- Susanne Ludwiczek
- Department of Internal Medicine, University of Innsbruck, Innsbruck, Austria
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Camaschella C. Understanding iron homeostasis through genetic analysis of hemochromatosis and related disorders. Blood 2005; 106:3710-7. [PMID: 16030190 DOI: 10.1182/blood-2005-05-1857] [Citation(s) in RCA: 150] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Genetic analysis of hemochromatosis has led to the discovery of a number of genes whose mutations disrupt iron homeostasis and lead to iron overload. The introduction of molecular tests into clinical practice has provided a tool for early diagnosis of these conditions. It has become clear that hemochromatosis includes a spectrum of disorders that range from simple biochemical abnormalities to chronic asymptomatic tissue damage in midlife to serious life-threatening diseases in young subjects. Molecular studies have identified the systemic loop that controls iron homeostasis and is centered on the hepcidin-ferroportin interaction. The complexity of this regulatory pathway accounts for the genetic heterogeneity of hemochromatosis and related disorders and raises the possibility that genes encoding components of the pathway may be modifiers of the main genotype. Molecular diagnosis has improved the classification of the genetic conditions leading to iron overload and identified novel entities, characterized by both iron loading and variable degrees of anemia. Despite the progress in the diagnosis, classification, and mechanisms of iron overload disorders, the treatment of affected patients continues to rely on regular phlebotomy. Understanding the molecular circuitry of iron control may lead to the identification of potential therapeutic targets for novel treatment strategies to be used in association with or as an alternative to phlebotomy.
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Affiliation(s)
- Clara Camaschella
- Università Vita-Salute and Istituto di Ricovero e Cura a Carratere Scientifico Ospedale San Raffaele, Via Olgettina, 60, 20132 Milano, Italy.
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43
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Makui H, Soares RJ, Jiang W, Constante M, Santos MM. Contribution of Hfe expression in macrophages to the regulation of hepatic hepcidin levels and iron loading. Blood 2005; 106:2189-95. [PMID: 15914561 PMCID: PMC2891009 DOI: 10.1182/blood-2005-02-0629] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
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.
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Affiliation(s)
- Hortence Makui
- Centre de recherche, CHUM-Hôpital Notre-Dame, Pav. De Sève Y5625, 1560 Sherbrooke est, Montréal, Québec H2L 4M1, Canada
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Abstract
PURPOSE OF REVIEW The number of newly identified genes participating in the regulation of iron homeostasis has continued to expand at a remarkable pace. The roles for many have begun to be elucidated and there is an increasing indication that hepatocytes play a central role in determining the level of intestinal iron absorption. Total body iron homeostasis is dependent upon carefully regulated absorption of dietary iron, thus these genes are of fundamental importance in understanding of pathophysiology of such common disorders as hereditary hemochromatosis (HH) and the anaemia of chronic diseases. RECENT FINDINGS The hepatic peptide hepcidin plays a key role as a circulating hormone that regulates the absorption of dietary iron from the duodenum. Hepcidin expression is inappropriately decreased in hereditary hemochromatosis and is abnormally increased in the anaemia of chronic diseases. Other hepatic proteins essential for normal iron homeostasis, including HFE, transferrin receptor 2 (TfR2), and hemojuvelin, function at least in part, by modulating the expression of hepcidin. SUMMARY New insights into the pathophysiology of hereditary hemochromatosis and the anaemia of chronic diseases have been achieved with the recognition of the central role for hepcidin as an iron regulatory hormone. Investigations into the biologic control of this hormone and its mechanism of action offer the possibility of new therapeutic approaches to disorders of iron metabolism.
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Affiliation(s)
- Robert E Fleming
- Saint Louis University School of Medicine, 1465 South Grand Avenue, Saint Louis, Missouri 63104, USA.
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45
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Cadet E, Gadenne M, Capron D, Rochette J. [Advances in iron metabolism: a transition state]. Rev Med Interne 2004; 26:315-24. [PMID: 15820567 DOI: 10.1016/j.revmed.2004.09.024] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2004] [Accepted: 09/19/2004] [Indexed: 11/16/2022]
Abstract
PURPOSE Advances towards the understanding of gene regulation and protein function recently discovered through iron metabolism disorders are the subject of this review. CURRENT KNOWLEDGE AND KEY POINTS Within a few years the discovery of genes that determine heritable defects of cellular iron uptake or regulation in mice as in humans have provided new insights for investigation into iron metabolism pathways. FUTURE PROSPECTS AND PROJECTS It is still unclear how connections are made between new proteins in iron uptake, trafficking and regulation of iron homeostasis. Gene expression studies using microarrays technology in different iron conditions should help to explore iron homeostasis further.
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Affiliation(s)
- E Cadet
- Service de génétique moléculaire médicale et UPRES EA 2629, CHU d'Amiens, université de Picardie-Jules-Verne, 3, rue des Louvels, 80036 Amiens cedex, France.
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46
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Fleming RE, Britton RS, Waheed A, Sly WS, Bacon BR. Pathogenesis of hereditary hemochromatosis. Clin Liver Dis 2004; 8:755-73, vii. [PMID: 15464654 DOI: 10.1016/j.cld.2004.06.004] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Hereditary hemochromatosis comprises several inherited disorders of iron homeostasis characterized by increased gastrointestinal iron absorpstion and resultant tissue iron deposition. The identification of HFE and other genes involved in iron metabolism has greatly expanded our understanding of hereditary hemochromatosis. Two major hypotheses have been proposed to explain the pathogenesis of HFE-related hereditary hemochromatosis: the hepcidin hypothesis and the duodenal crypt cell programming hypothesis.
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Affiliation(s)
- Robert E Fleming
- Department of Pediatrics, Saint Louis University School of Medicine, Cardinal Glennon Childrens Hospital, 1465 S. Grand Blvd, St. Louis, MO 63104, USA.
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47
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Mura C, Le Gac G, Jacolot S, Férec C. Transcriptional regulation of the human HFE gene indicates high liver expression and erythropoiesis coregulation. FASEB J 2004; 18:1922-4. [PMID: 15467009 DOI: 10.1096/fj.04-2520fje] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The human HFE gene is clearly involved in hereditary hemochromatosis, a common autosomal recessive genetic disorder of iron homeostasis. However, the precise role of the HFE protein is still undefined. Here, to obtain new insight, we analyzed the transcriptional regulation of HFE gene and defined the functional organization of the HFE promoter. Both in vitro transcription and reporter gene assay in transient transfection evidenced a high liver expression of the HFE mRNA. The 5' end analysis of mRNA showed two major initiation sites localized at -265 and -195 directed by TATA-like sequences and a window of initiation within the -120 to -10 GC-rich region upstream of the first coding nucleotide. Positive cis-regulating elements were characterized within the -1057/-8 region, and a negative one extending upstream (-1485/-1057) was identified. DNase I footprinting analysis and gel shift assay revealed several protein binding sites, and subsequent functional analysis evidenced transactivation of HFE by liver-enriched C/EBPalpha, erythropoietic-specific GATA-1, and ubiquitous Sp1 transcription factors. These data bring some evidence of a role of HFE in the liver and a coregulation with erythropoiesis as other genes involved in iron homeostasis.
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Affiliation(s)
- Catherine Mura
- INSERM U613, Génétique Moléculaire et Génétique Epidémiologique, UBO, 46 rue Félix Le Dantec, Brest 29200, France.
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48
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Sassi R, Hmida S, Kaabi H, Hajjej A, Abid A, Abdelkefi S, Yacoub S, Maamar M, Mojaat N, Ben Hamed L, Bellali H, Dridi A, Jridi A, Midouni B, Boukef MK. Prevalence of C282Y and H63D mutations in the haemochromatosis (HFE) gene in Tunisian population. ACTA ACUST UNITED AC 2004; 47:325-30. [PMID: 15581829 DOI: 10.1016/j.anngen.2004.05.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2004] [Accepted: 05/05/2004] [Indexed: 11/25/2022]
Abstract
The studies of the HFE mutations: H63D and C282Y in North African populations have revealed the extreme rarity or even the absence of the C282Y mutation. We have examined 1140 chromosomes (570 Tunisian people) for the presence of the two HFE mutations by PCR-RFLP analysis. We have found that the allele frequencies are, respectively, 15.17% (+/-2.1%) for the H63D and 0.09% (+/-0.17%) for the C282Y. These results are consistent with the worldwide spread of the H63D mutation and the north European restriction of the C282Y. This study will be completed by determining whether homozygote trait for H63D and associated risk factors (beta thalassémia) can lead to iron overload in Tunisia.
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Affiliation(s)
- R Sassi
- National Blood Transfusion Centre, Rue Djebel Lakdhar Bab Saadoun, 1006 Tunis, Tunisia
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Chua ACG, Olynyk JK, Leedman PJ, Trinder D. Nontransferrin-bound iron uptake by hepatocytes is increased in the Hfe knockout mouse model of hereditary hemochromatosis. Blood 2004; 104:1519-25. [PMID: 15155457 DOI: 10.1182/blood-2003-11-3872] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Hereditary hemochromatosis (HH) is an iron-overload disorder caused by a C282Y mutation in the HFE gene. In HH, plasma nontransferrin-bound iron (NTBI) levels are increased and NTBI is bound mainly by citrate. The aim of this study was to examine the importance of NTBI in the pathogenesis of hepatic iron loading in Hfe knockout mice. Plasma NTBI levels were increased 2.5-fold in Hfe knockout mice compared with control mice. Total ferric citrate uptake by hepatocytes isolated from Hfe knockout mice (34.1 +/- 2.8 pmol Fe/mg protein/min) increased by 2-fold compared with control mice (17.8 +/- 2.7 pmol Fe/mg protein/min; P <.001; mean +/- SEM; n = 7). Ferrous ion chelators, bathophenanthroline disulfonate, and 2',2-bipyridine inhibited ferric citrate uptake by hepatocytes from both mouse types. Divalent metal ions inhibited ferric citrate uptake by hepatocytes, as did diferric transferrin. Divalent metal transporter 1 (DMT1) mRNA and protein expression was increased approximately 2-fold by hepatocytes from Hfe knockout mice. We conclude that NTBI uptake by hepatocytes from Hfe knockout mice contributed to hepatic iron loading. Ferric ion was reduced to ferrous ion and taken up by hepatocytes by a pathway shared with diferric transferrin. Inhibition of uptake by divalent metals and up-regulation of DMT1 expression suggested that NTBI uptake was mediated by DMT1.
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Affiliation(s)
- Anita C G Chua
- School of Medicine and Pharmacology, The University of Western Australia, Fremantle Hospital, PO Box 480, Fremantle 6959, WA, Australia
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50
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Brissot P, Troadec MB, Loréal O. Intestinal absorption of iron in HFE-1 hemochromatosis: local or systemic process? J Hepatol 2004; 40:702-9. [PMID: 15030990 DOI: 10.1016/j.jhep.2004.01.020] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Pierre Brissot
- Service des Maladies du Foie and Inserm Unit U-522, University Hospital Pontchaillou, Rennes, France.
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