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Atanasio A, Bernabini S, Consagra A, Giotti I, Carrai V, Pelo E, Vannucchi AM. Testing for rare types of Hereditary Hemochromatosis. A genetic study of two Italian families affected by early onset iron overload. Int J Lab Hematol 2023; 45:784-787. [PMID: 36949728 DOI: 10.1111/ijlh.14062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Accepted: 03/13/2023] [Indexed: 03/24/2023]
Affiliation(s)
- Alessandro Atanasio
- CRIMM, Centre of Research and Innovation in Myeloproliferative Neoplasms, University of Florence, Florence, Italy
- Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy
| | - Sara Bernabini
- Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy
- Genetic Diagnostic Unit, Careggi University Hospital, Florence, Italy
| | - Angela Consagra
- Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy
| | - Irene Giotti
- Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy
- Genetic Diagnostic Unit, Careggi University Hospital, Florence, Italy
| | - Valentina Carrai
- Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy
| | - Elisabetta Pelo
- Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy
- Genetic Diagnostic Unit, Careggi University Hospital, Florence, Italy
| | - Alessandro Maria Vannucchi
- CRIMM, Centre of Research and Innovation in Myeloproliferative Neoplasms, University of Florence, Florence, Italy
- Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy
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2
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Baas FS, Rishi G, Swinkels DW, Subramaniam VN. Genetic Diagnosis in Hereditary Hemochromatosis: Discovering and Understanding the Biological Relevance of Variants. Clin Chem 2021; 67:1324-1341. [PMID: 34402502 DOI: 10.1093/clinchem/hvab130] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Accepted: 06/23/2021] [Indexed: 11/13/2022]
Abstract
BACKGROUND Hereditary hemochromatosis (HH) is a genetic disease, leading to iron accumulation and possible organ damage. Patients are usually homozygous for p. Cys282Tyr in the homeostatic iron regulator gene but may have mutations in other genes involved in the regulation of iron. Next-generation sequencing is increasingly being utilized for the diagnosis of patients, leading to the discovery of novel genetic variants. The clinical significance of these variants is often unknown. CONTENT Determining the pathogenicity of such variants of unknown significance is important for diagnostics and genetic counseling. Predictions can be made using in silico computational tools and population data, but additional evidence is required for a conclusive pathogenicity classification. Genetic disease models, such as in vitro models using cellular overexpression, induced pluripotent stem cells or organoids, and in vivo models using mice or zebrafish all have their own challenges and opportunities when used to model HH and other iron disorders. Recent developments in gene-editing technologies are transforming the field of genetic disease modeling. SUMMARY In summary, this review addresses methods and developments regarding the discovery and classification of genetic variants, from in silico tools to in vitro and in vivo models, and presents them in the context of HH. It also explores recent gene-editing developments and how they can be applied to the discussed models of genetic disease.
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Affiliation(s)
- Floor S Baas
- Translational Metabolic Laboratory (TML 831), Radboudumc, Nijmegen, the Netherlands.,Hepatogenomics Research Group, School of Biomedical Sciences, Queensland University of Technology (QUT), Brisbane, QLD, Australia
| | - Gautam Rishi
- Hepatogenomics Research Group, School of Biomedical Sciences, Queensland University of Technology (QUT), Brisbane, QLD, Australia
| | - Dorine W Swinkels
- Translational Metabolic Laboratory (TML 831), Radboudumc, Nijmegen, the Netherlands
| | - V Nathan Subramaniam
- Hepatogenomics Research Group, School of Biomedical Sciences, Queensland University of Technology (QUT), Brisbane, QLD, Australia
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Kowdley DS, Kowdley KV. Appropriate Clinical Genetic Testing of Hemochromatosis Type 2-4, Including Ferroportin Disease. Appl Clin Genet 2021; 14:353-361. [PMID: 34413666 PMCID: PMC8369226 DOI: 10.2147/tacg.s269622] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Accepted: 07/18/2021] [Indexed: 11/23/2022] Open
Abstract
Hereditary hemochromatosis (HH) is an inherited iron overload disorder due to a deficiency of hepcidin, or a failure of hepcidin to degrade ferroportin. The most common form of HH, Type 1 HH, is most commonly due to a homozygous C282Y mutation in HFE and is relatively well understood in significance and action; however, other rare forms of HH (Types 2–4) exist and are more difficult to identify and diagnose in clinical practice. In this review, we describe the clinical characteristics of HH Type 2–4 and the mutation patterns that have been described in these conditions. We also review the different methods for genetic testing available in clinical practice and a pragmatic approach to the patient with suspected non-HFE HH.
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Affiliation(s)
- Devan S Kowdley
- Liver Institute Northwest and Elson S. Floyd College of Medicine, Washington State University, Seattle, WA, USA
| | - Kris V Kowdley
- Liver Institute Northwest and Elson S. Floyd College of Medicine, Washington State University, Seattle, WA, USA
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4
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Evidence for dimerization of ferroportin in a human hepatic cell line using proximity ligation assays. Biosci Rep 2021; 40:222672. [PMID: 32301493 PMCID: PMC7201565 DOI: 10.1042/bsr20191499] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2019] [Revised: 04/08/2020] [Accepted: 04/16/2020] [Indexed: 12/30/2022] Open
Abstract
Mutations in the only known iron exporter ferroportin (FPN) in humans are associated with the autosomal dominantly inherited iron overload disorder ferroportin disease or type IV hereditary hemochromatosis (HH). While our knowledge of the central role of FPN in iron homeostasis has grown in the last 20 years, there exist some questions surrounding the structure and membrane topology of FPN with conflicting data on whether this receptor acts as a monomer or a multimer. To investigate and determine if FPN dimerization occurs in cells, we used novel tools including a variety of different FPN constructs expressing different tagged versions of the protein, a novel antibody that only detects cell surface FPN and proximity ligation assays. The results of the present study suggest that both the carboxy- and amino-termini of the FPN protein are intracellular. We also show that exogenously transfected FPN forms dimers; these dimers can be formed between the wild-type and mutant FPN proteins. This is the first study to examine the intracellular dimerization of FPN protein. Using proximity ligation assays, we show intracellular localization of FPN dimers and the interaction between FPN and hepcidin proteins as well. These results have important implications in the field of iron metabolism and add to our knowledge about FPN membrane topology and physiology of iron transport. This will be of importance in understanding the clinical implications of FPN mutations and of interest to future research aimed at targeting FPN expression to modulate iron homeostasis.
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Liu B, Song Z, Fan Y, Zhang G, Cao P, Li D, Liu X, Chang Y, Tan K. Downregulation of FPN1 acts as a prognostic biomarker associated with immune infiltration in lung cancer. Aging (Albany NY) 2021; 13:8737-8761. [PMID: 33714956 PMCID: PMC8034901 DOI: 10.18632/aging.202685] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Accepted: 02/01/2021] [Indexed: 12/24/2022]
Abstract
Lung cancer morbidity and mortality remain the leading causes of tumor-associated death worldwide. The discovery of early diagnostic and prognostic markers of lung cancer could significantly improve the survival rate and decrease the mortality rate. FPN1 is the only known mammalian iron exporter. However, the molecular and biological functions of FPN1 in lung cancer remain unclear. Here, FPN1 mRNA expression in lung cancer was estimated using the TCGA, Oncomine, TIMER, and UALCAN databases. The prognostic role of FPN1 was evaluated using Kaplan-Meier plotter and PrognoScan. Associations between FPN1 and immune infiltration in lung cancer were evaluated by the TIMER and CIBERSORT algorithms. FPN1 mRNA and protein expressions were significantly downregulated in lung cancer. Low FPN1 expression was strongly related to worse prognosis in patients with lung cancer. GO and KEGG analyses and GSEA suggested that FPN1 was remarkably related to iron homeostasis and immunity. Importantly, FPN1 was remarkably associated with the infiltrating abundance of multiple immune cells. Moreover, FPN1 displayed a strong correlation with various immune marker sets. We investigated the clinical application value of FPN1 and provided a basis for the sensitive diagnosis, prognostication and targeted therapy of lung cancer.
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Affiliation(s)
- Bing Liu
- Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology of Hebei Province, College of Life Sciences, Hebei Normal University, Shijiazhuang 050024, Hebei, China
| | - Zhiyuan Song
- Department of Neurosurgery, HanDan Central Hospital, Handan 056001, Hebei, China
| | - Yumei Fan
- Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology of Hebei Province, College of Life Sciences, Hebei Normal University, Shijiazhuang 050024, Hebei, China
| | - Guangyu Zhang
- Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology of Hebei Province, College of Life Sciences, Hebei Normal University, Shijiazhuang 050024, Hebei, China
| | - Pengxiu Cao
- Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology of Hebei Province, College of Life Sciences, Hebei Normal University, Shijiazhuang 050024, Hebei, China
| | - Danyu Li
- Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology of Hebei Province, College of Life Sciences, Hebei Normal University, Shijiazhuang 050024, Hebei, China
| | - Xiaopeng Liu
- Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology of Hebei Province, College of Life Sciences, Hebei Normal University, Shijiazhuang 050024, Hebei, China.,Department of Neurosurgery, The Second Hospital of Hebei Medical University, Shijiazhuang 050000, Hebei, China
| | - Yanzhong Chang
- Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology of Hebei Province, College of Life Sciences, Hebei Normal University, Shijiazhuang 050024, Hebei, China
| | - Ke Tan
- Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology of Hebei Province, College of Life Sciences, Hebei Normal University, Shijiazhuang 050024, Hebei, China
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Le Tertre M, Ka C, Raud L, Berlivet I, Gourlaouen I, Richard G, Uguen K, Chen JM, Férec C, Fichou Y, Le Gac G. Splicing analysis of SLC40A1 missense variations and contribution to hemochromatosis type 4 phenotypes. Blood Cells Mol Dis 2020; 87:102527. [PMID: 33341511 DOI: 10.1016/j.bcmd.2020.102527] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 11/24/2020] [Accepted: 11/24/2020] [Indexed: 02/09/2023]
Abstract
Hemochromatosis type 4, or ferroportin disease, is considered as the second leading cause of primary iron overload after HFE-related hemochromatosis. The disease, which is predominantly associated with missense variations in the SLC40A1 gene, is characterized by wide clinical heterogeneity. We tested the possibility that some of the reported missense mutations, despite their positions within exons, cause splicing defects. Fifty-eight genetic variants were selected from the literature based on two criteria: a precise description of the nucleotide change and individual evidence of iron overload. The selected variants were investigated by different in silico prediction tools and prioritized for midigene splicing assays. Of the 15 variations tested in vitro, only two were associated with splicing changes. We confirm that the c.1402G>A transition (p.Gly468Ser) disrupts the exon 7 donor site, leading to the use of an exonic cryptic splicing site and the generation of a truncated reading frame. We observed, for the first time, that the p.Gly468Ser substitution has no effect on the ferroportin iron export function. We demonstrate alternative splicing of exon 5 in different cell lines and show that the c.430A>G (p.Asn144Asp) variant promotes exon 5 inclusion. This could be part of a gain-of-function mechanism. We conclude that splicing mutations rarely contribute to hemochromatosis type 4 phenotypes. An in-depth investigation of exon 5 auxiliary splicing sequences may help to elucidate the mechanism by which splicing regulatory proteins regulate the production of the full length SLC40A1 transcript and to clarify its physiological importance.
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Affiliation(s)
- Marlène Le Tertre
- Univ Brest, Inserm, EFS, UMR1078, GGB, F-29200, France; CHRU de Brest, Service de Génétique Médicale et Biologie de la Reproduction, Laboratoire de Génétique Moléculaire et Histocompatibilité, F-29200, France
| | - Chandran Ka
- Univ Brest, Inserm, EFS, UMR1078, GGB, F-29200, France; CHRU de Brest, Service de Génétique Médicale et Biologie de la Reproduction, Laboratoire de Génétique Moléculaire et Histocompatibilité, F-29200, France; Laboratory of Excellence GR-Ex, F-75015, France
| | - Loann Raud
- Univ Brest, Inserm, EFS, UMR1078, GGB, F-29200, France; Association Gaétan Saleün, F-29200, France
| | | | - Isabelle Gourlaouen
- Univ Brest, Inserm, EFS, UMR1078, GGB, F-29200, France; Laboratory of Excellence GR-Ex, F-75015, France
| | | | - Kévin Uguen
- Univ Brest, Inserm, EFS, UMR1078, GGB, F-29200, France; CHRU de Brest, Service de Génétique Médicale et Biologie de la Reproduction, Laboratoire de Génétique Moléculaire et Histocompatibilité, F-29200, France
| | - Jian-Min Chen
- Univ Brest, Inserm, EFS, UMR1078, GGB, F-29200, France
| | - Claude Férec
- Univ Brest, Inserm, EFS, UMR1078, GGB, F-29200, France; CHRU de Brest, Service de Génétique Médicale et Biologie de la Reproduction, Laboratoire de Génétique Moléculaire et Histocompatibilité, F-29200, France; Association Gaétan Saleün, F-29200, France
| | - Yann Fichou
- Univ Brest, Inserm, EFS, UMR1078, GGB, F-29200, France; Laboratory of Excellence GR-Ex, F-75015, France
| | - Gérald Le Gac
- Univ Brest, Inserm, EFS, UMR1078, GGB, F-29200, France; CHRU de Brest, Service de Génétique Médicale et Biologie de la Reproduction, Laboratoire de Génétique Moléculaire et Histocompatibilité, F-29200, France; Laboratory of Excellence GR-Ex, F-75015, France.
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7
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Ravasi G, Pelucchi S, Russo A, Mariani R, Piperno A. Ferroportin disease: A novel SLC40A1 mutation. Dig Liver Dis 2020; 52:688-690. [PMID: 32360131 DOI: 10.1016/j.dld.2020.03.013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 03/12/2020] [Accepted: 03/16/2020] [Indexed: 12/11/2022]
Affiliation(s)
- Giulia Ravasi
- University of Milano-Bicocca - Department of Medicine and Surgery, Monza, Italy
| | - Sara Pelucchi
- University of Milano-Bicocca - Department of Medicine and Surgery, Monza, Italy
| | - Andrea Russo
- Medical Genetics - ASST-Monza, S.Gerardo Hospital, Monza, Italy
| | - Raffaella Mariani
- Centre for Rare Diseases - Disorders of Iron Metabolism - ASST-Monza, EuroBloodNet Referral Centre, S.Gerardo Hospital, Monza, Italy
| | - Alberto Piperno
- University of Milano-Bicocca - Department of Medicine and Surgery, Monza, Italy; Medical Genetics - ASST-Monza, S.Gerardo Hospital, Monza, Italy; Centre for Rare Diseases - Disorders of Iron Metabolism - ASST-Monza, EuroBloodNet Referral Centre, S.Gerardo Hospital, Monza, Italy.
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8
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Vlasveld LT, Janssen R, Bardou-Jacquet E, Venselaar H, Hamdi-Roze H, Drakesmith H, Swinkels DW. Twenty Years of Ferroportin Disease: A Review or An Update of Published Clinical, Biochemical, Molecular, and Functional Features. Pharmaceuticals (Basel) 2019; 12:ph12030132. [PMID: 31505869 PMCID: PMC6789780 DOI: 10.3390/ph12030132] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Revised: 08/14/2019] [Accepted: 08/20/2019] [Indexed: 12/14/2022] Open
Abstract
Iron overloading disorders linked to mutations in ferroportin have diverse phenotypes in vivo, and the effects of mutations on ferroportin in vitro range from loss of function (LOF) to gain of function (GOF) with hepcidin resistance. We reviewed 359 patients with 60 ferroportin variants. Overall, macrophage iron overload and low/normal transferrin saturation (TSAT) segregated with mutations that caused LOF, while GOF mutations were linked to high TSAT and parenchymal iron accumulation. However, the pathogenicity of individual variants is difficult to establish due to the lack of sufficiently reported data, large inter-assay variability of functional studies, and the uncertainty associated with the performance of available in silico prediction models. Since the phenotypes of hepcidin-resistant GOF variants are indistinguishable from the other types of hereditary hemochromatosis (HH), these variants may be categorized as ferroportin-associated HH, while the entity ferroportin disease may be confined to patients with LOF variants. To further improve the management of ferroportin disease, we advocate for a global registry, with standardized clinical analysis and validation of the functional tests preferably performed in human-derived enterocytic and macrophagic cell lines. Moreover, studies are warranted to unravel the definite structure of ferroportin and the indispensable residues that are essential for functionality.
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Affiliation(s)
- L Tom Vlasveld
- Department of Internal Medicine, Haaglanden MC-Bronovo, 2597AX The Hague, The Netherlands
| | - Roel Janssen
- Department of Laboratory Medicine, Translational Metabolic Laboratory, Radboud University Medical Center, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands
| | - Edouard Bardou-Jacquet
- Liver Diseases Department, French Reference Centre for Rare Iron Overload Diseases of Genetic Origin, University Hospital Pontchaillou, 35033 Rennes, France
| | - Hanka Venselaar
- Centre for Molecular and Biomolecular Informatics, Radboud Institute for Molecular Life Sciences, Radboud, University Medical Center, P.O. Box 9191, 6500 HB Nijmegen, The Netherlands
| | - Houda Hamdi-Roze
- Molecular Genetics Department, French Reference Centre for Rare Iron Overload Diseases of Genetic Origin, University Hospital Pontchaillou, 35033 Rennes, France
| | - Hal Drakesmith
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX39DS, UK
| | - Dorine W Swinkels
- Department of Laboratory Medicine, Translational Metabolic Laboratory, Radboud University Medical Center, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands.
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Ka C, Guellec J, Pepermans X, Kannengiesser C, Ged C, Wuyts W, Cassiman D, de Ledinghen V, Varet B, de Kerguenec C, Oudin C, Gourlaouen I, Lefebvre T, Férec C, Callebaut I, Le Gac G. The SLC40A1 R178Q mutation is a recurrent cause of hemochromatosis and is associated with a novel pathogenic mechanism. Haematologica 2018; 103:1796-1805. [PMID: 30002125 PMCID: PMC6278975 DOI: 10.3324/haematol.2018.189845] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Accepted: 07/06/2018] [Indexed: 12/29/2022] Open
Abstract
Hemochromatosis type 4 is one of the most common causes of primary iron overload, after HFE-related hemochromatosis. It is an autosomal dominant disorder, primarily due to missense mutations in SLC40A1. This gene encodes ferroportin 1 (FPN1), which is the sole iron export protein reported in mammals. Not all heterozygous missense mutations in SLC40A1 are disease-causing. Due to phenocopies and an increased demand for genetic testing, rare SLC40A1 variations are fortuitously observed in patients with a secondary cause of hyperferritinemia. Structure/function analysis is the most effective way of establishing causality when clinical and segregation data are lacking. It can also provide important insights into the mechanism of iron egress and FPN1 regulation by hepcidin. The present study aimed to determine the pathogenicity of the previously reported p.Arg178Gln variant. We present the biological, clinical, histological and radiological findings of 22 patients from six independent families of French, Belgian or Iraqi decent. Despite phenotypic variability, all patients with p.Arg178Gln had elevated serum ferritin concentrations and normal to low transferrin saturation levels. In vitro experiments demonstrated that the p.Arg178Gln mutant reduces the ability of FPN1 to export iron without causing protein mislocalization. Based on a comparative model of the 3D structure of human FPN1 in an outward facing conformation, we argue that p.Arg178 is part of an interaction network modulating the conformational changes required for iron transport. We conclude that p.Arg178Gln represents a new category of loss-of-function mutations and that the study of “gating residues” is necessary in order to fully understand the action mechanism of FPN1.
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Affiliation(s)
- Chandran Ka
- UMR1078, INSERM, Université Bretagne Loire - Université de Bretagne Occidentale, Etablissement Français du Sang - Bretagne, Institut Brestois Santé-Agro-Matière, Brest, France.,Laboratoire de Génétique Moléculaire et Histocompatibilité, CHRU de Brest, Hôpital Morvan, France.,Laboratory of Excellence GR-Ex, Paris, France
| | - Julie Guellec
- UMR1078, INSERM, Université Bretagne Loire - Université de Bretagne Occidentale, Etablissement Français du Sang - Bretagne, Institut Brestois Santé-Agro-Matière, Brest, France.,Laboratory of Excellence GR-Ex, Paris, France.,Association Gaetan Saleun, Brest, France
| | - Xavier Pepermans
- Center for Human Genetics, University Hospital of St-Luc, Brussels, Belgium
| | - Caroline Kannengiesser
- Laboratory of Excellence GR-Ex, Paris, France.,UMR1149, INSERM, Centre de Recherche sur l'Inflammation, Université Paris Diderot, AP-HP, Hôpital Bichat, Département de Génétique, France.,On behalf of the French National Network for the Molecular Diagnosis of Inherited Iron Overload Disorders (J. Rochette, E. Cadet, C. Kannengiesser, H. Puy, C. Ged, H. de Verneuil, G. Le Gac, C. Férec, S. Pissard, V. Gérolami), Brest, France
| | - Cécile Ged
- On behalf of the French National Network for the Molecular Diagnosis of Inherited Iron Overload Disorders (J. Rochette, E. Cadet, C. Kannengiesser, H. Puy, C. Ged, H. de Verneuil, G. Le Gac, C. Férec, S. Pissard, V. Gérolami), Brest, France.,INSERM U1035, BMGIC, CHU de Bordeaux, Laboratoire de Biochimie et Biologie Moléculaire, France
| | - Wim Wuyts
- Department of Medical Genetics, University and University Hospital of Antwerp, Edegem, Belgium
| | - David Cassiman
- Department of Gastroenterology-Hepatology and Metabolic Center, University Hospital of Leuven, Belgium
| | - Victor de Ledinghen
- Department of Gastroenterology and Digestive Oncology, University Hospital of Bordeaux, France
| | - Bruno Varet
- Université Paris Descartes et AP-HP, Hôpital Necker, Service d'Hématologie, France
| | | | - Claire Oudin
- UMR1149, INSERM, Centre de Recherche sur l'Inflammation, Université Paris Diderot, AP-HP, Hôpital Bichat, Département de Génétique, France
| | - Isabelle Gourlaouen
- UMR1078, INSERM, Université Bretagne Loire - Université de Bretagne Occidentale, Etablissement Français du Sang - Bretagne, Institut Brestois Santé-Agro-Matière, Brest, France.,Laboratory of Excellence GR-Ex, Paris, France
| | - Thibaud Lefebvre
- UMR1149, INSERM, Centre de Recherche sur l'Inflammation, Université Paris Diderot, AP-HP, Hôpital Bichat, Département de Génétique, France
| | - Claude Férec
- UMR1078, INSERM, Université Bretagne Loire - Université de Bretagne Occidentale, Etablissement Français du Sang - Bretagne, Institut Brestois Santé-Agro-Matière, Brest, France.,Laboratoire de Génétique Moléculaire et Histocompatibilité, CHRU de Brest, Hôpital Morvan, France.,On behalf of the French National Network for the Molecular Diagnosis of Inherited Iron Overload Disorders (J. Rochette, E. Cadet, C. Kannengiesser, H. Puy, C. Ged, H. de Verneuil, G. Le Gac, C. Férec, S. Pissard, V. Gérolami), Brest, France
| | - Isabelle Callebaut
- UMR7590, CNRS, Sorbonne Universités, Université Pierre et Marie Curie-Paris, France
| | - Gérald Le Gac
- UMR1078, INSERM, Université Bretagne Loire - Université de Bretagne Occidentale, Etablissement Français du Sang - Bretagne, Institut Brestois Santé-Agro-Matière, Brest, France .,Laboratoire de Génétique Moléculaire et Histocompatibilité, CHRU de Brest, Hôpital Morvan, France.,Laboratory of Excellence GR-Ex, Paris, France.,On behalf of the French National Network for the Molecular Diagnosis of Inherited Iron Overload Disorders (J. Rochette, E. Cadet, C. Kannengiesser, H. Puy, C. Ged, H. de Verneuil, G. Le Gac, C. Férec, S. Pissard, V. Gérolami), Brest, France
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Pietrangelo A. Ferroportin disease: pathogenesis, diagnosis and treatment. Haematologica 2017; 102:1972-1984. [PMID: 29101207 PMCID: PMC5709096 DOI: 10.3324/haematol.2017.170720] [Citation(s) in RCA: 87] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2017] [Accepted: 09/25/2017] [Indexed: 12/14/2022] Open
Abstract
Ferroportin Disease (FD) is an autosomal dominant hereditary iron loading disorder associated with heterozygote mutations of the ferroportin-1 (FPN) gene. It represents one of the commonest causes of genetic hyperferritinemia, regardless of ethnicity. FPN1 transfers iron from the intestine, macrophages and placenta into the bloodstream. In FD, loss-of-function mutations of FPN1 limit but do not impair iron export in enterocytes, but they do severely affect iron transfer in macrophages. This leads to progressive and preferential iron trapping in tissue macrophages, reduced iron release to serum transferrin (i.e. inappropriately low transferrin saturation) and a tendency towards anemia at menarche or after intense bloodletting. The hallmark of FD is marked iron accumulation in hepatic Kupffer cells. Numerous FD-associated mutations have been reported worldwide, with a few occurring in different populations and some more commonly reported (e.g. Val192del, A77D, and G80S). FPN1 polymorphisms also represent the gene variants most commonly responsible for hyperferritinemia in Africans. Differential diagnosis includes mainly hereditary hemochromatosis, the syndrome commonly due to either HFE or TfR2, HJV, HAMP, and, in rare instances, FPN1 itself. Here, unlike FD, hyperferritinemia associates with high transferrin saturation, iron-spared macrophages, and progressive parenchymal cell iron load. Abdominal magnetic resonance imaging (MRI), the key non-invasive diagnostic tool for the diagnosis of FD, shows the characteristic iron loading SSL triad (spleen, spine and liver). A non-aggressive phlebotomy regimen is recommended, with careful monitoring of transferrin saturation and hemoglobin due to the risk of anemia. Family screening is mandatory since siblings and offspring have a 50% chance of carrying the pathogenic mutation.
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Affiliation(s)
- Antonello Pietrangelo
- Center for Hemochromatosis, Department of Internal Medicine II, University of Modena and Reggio Emilia Policlinico, Modena, Italy
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11
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The three isoforms of hepcidin in human serum and their processing determined by liquid chromatography-tandem mass spectrometry (LC-tandem MS). Int J Hematol 2016; 103:34-43. [PMID: 26462810 DOI: 10.1007/s12185-015-1885-y] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2015] [Revised: 10/01/2015] [Accepted: 10/01/2015] [Indexed: 10/23/2022]
Abstract
Hepcidin, the iron regulatory hormone, has three isoforms; -20, -22 and -25. While hepcidin-25 has been studied extensively, the physiological significance of other isoforms remains poorly understood. Using a quantitative method based on liquid chromatography-tandem mass spectrometry (LC-tandem MS) developed by our group, we quantified hepcidin isoforms in human serum to elucidate their characteristics, and investigated the role of hepatocytes in isoform processing. Hepcidin isoforms in serum obtained from 40 healthy volunteers were quantified. Synthetic hepcidin peptides were added to healthy serum, and to HepG2 culture media, and hepcidin isoform concentrations determined. All three hepcidin isoforms were detected in human serum; however, hepcidin-25 concentrations were highest. The three hepcidin isoforms showed a strong positive correlation with each other and with serum ferritin. Additionally, while hepcidin-20 was strongly correlated with serum creatinine, the other isoforms were not. Hepcidin-20 and -25 levels were also increased in chronic kidney disease (CKD) serum. Hepcidin-22 rapidly degraded into hepcidin-20, whereas hepcidin-25 remained relatively stable. Finally, hepcidin-22 degradation into hepcidin-20 was accelerated in the presence of HepG2. This method has enabled us to reveal fundamental characteristics of the three hepcidin isoforms in serum and may be a powerful tool for quantifying hepcidin isoform expression and processing.
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12
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Badar S, Busti F, Ferrarini A, Xumerle L, Bozzini P, Capelli P, Pozzi-Mucelli R, Campostrini N, De Matteis G, Marin Vargas S, Giorgetti A, Delledonne M, Olivieri O, Girelli D. Identification of novel mutations in hemochromatosis genes by targeted next generation sequencing in Italian patients with unexplained iron overload. Am J Hematol 2016; 91:420-5. [PMID: 26799139 DOI: 10.1002/ajh.24304] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Revised: 01/08/2016] [Accepted: 01/13/2016] [Indexed: 12/14/2022]
Abstract
Hereditary hemochromatosis, one of the commonest genetic disorder in Caucasians, is mainly associated to homozygosity for the C282Y mutation in the HFE gene, which is highly prevalent (allele frequency up to near 10% in Northern Europe) and easily detectable through a widely available "first level" molecular test. However, in certain geographical regions like the Mediterranean area, up to 30% of patients with a HH phenotype has a negative or non-diagnostic (i.e. simple heterozygosity) test, because of a known heterogeneity involving at least four other genes (HAMP, HJV, TFR2, and SLC40A1). Mutations in such genes are generally rare/private, making the diagnosis of atypical HH essentially a matter of exclusion in clinical practice (from here the term of "non-HFE" HH), unless cumbersome traditional sequencing is applied. We developed a Next Generation Sequencing (NGS)-based test targeting the five HH genes, and applied it to patients with clinically relevant iron overload (IO) and a non-diagnostic first level genetic test. We identified several mutations, some of which were novel (i.e. HFE W163X, HAMP R59X, and TFR2 D555N) and allowed molecular reclassification of "non-HFE" HH clinical diagnosis, particularly in some highly selected IO patients without concurring acquired risk factors. This NGS-based "second level" genetic test may represent a useful tool for molecular diagnosis of HH in patients in whom HH phenotype remains unexplained after the search of common HFE mutations.
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Affiliation(s)
- Sadaf Badar
- Department of Medicine; Section of Internal Medicine, University of Verona; Verona Italy
| | - Fabiana Busti
- Department of Medicine; Section of Internal Medicine, University of Verona; Verona Italy
| | | | - Luciano Xumerle
- Department of Biotechnology; University of Verona; Verona Italy
| | - Paolo Bozzini
- Department of Medicine; Section of Internal Medicine, University of Verona; Verona Italy
| | - Paola Capelli
- Unit of Pathology, Azienda Ospedaliera Universitaria Integrata Verona; Verona Italy
| | - Roberto Pozzi-Mucelli
- Department of Diagnostics and Public Health; Section of Radiology, University of Verona; Verona Italy
| | - Natascia Campostrini
- Department of Medicine; Section of Internal Medicine, University of Verona; Verona Italy
| | - Giovanna De Matteis
- Unit of Clinical Chemistry, Azienda Ospedaliera Universitaria Integrata Verona; Verona Italy
| | | | | | | | - Oliviero Olivieri
- Department of Medicine; Section of Internal Medicine, University of Verona; Verona Italy
| | - Domenico Girelli
- Department of Medicine; Section of Internal Medicine, University of Verona; Verona Italy
- Veneto Regional Referral Center for Iron Metabolism Disorders, GIMFer (Gruppo Interdisciplinare Sulle Malattie Del Ferro); Azienda Ospedaliera Uiversitaria Integrata Verona; Verona Italy
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13
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Detection of a rare mutation in the ferroportin gene through targeted next generation sequencing. BLOOD TRANSFUSION = TRASFUSIONE DEL SANGUE 2016; 14:531-534. [PMID: 27177411 DOI: 10.2450/2016.0286-15] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Accepted: 02/04/2016] [Indexed: 12/20/2022]
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14
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Bonaccorsi di Patti MC, Polticelli F, Tortosa V, Furbetta PA, Musci G. A bacterial homologue of the human iron exporter ferroportin. FEBS Lett 2015; 589:3829-35. [PMID: 26608034 DOI: 10.1016/j.febslet.2015.11.025] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2015] [Revised: 11/13/2015] [Accepted: 11/16/2015] [Indexed: 10/22/2022]
Abstract
A bacterial homologue of the human iron exporter ferroportin found in the predatory Gram-negative bacterium Bdellovibrio bacteriovorus has been investigated. Molecular modelling, expression in recombinant form and iron binding and transport assays demonstrate that B. bacteriovorus ferroportin (bdFpn) is indeed an orthologue of human ferroportin. Key residues corresponding to those essential for iron binding and transport in human ferroportin are conserved in the bacterial homologue and are predicted to be correctly clustered in the central cavity of the protein. Mutation of these residues grossly affects the iron binding and transport ability of bdFpn.
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Affiliation(s)
| | - Fabio Polticelli
- Department of Sciences, Roma Tre University, Rome, Italy; National Institute of Nuclear Physics, Roma Tre Section, Rome, Italy.
| | | | | | - Giovanni Musci
- Department of Biosciences and Territory, University of Molise, Pesche, Italy.
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15
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Bonaccorsi di Patti MC, Polticelli F, Cece G, Cutone A, Felici F, Persichini T, Musci G. A structural model of human ferroportin and of its iron binding site. FEBS J 2014; 281:2851-60. [PMID: 24767627 DOI: 10.1111/febs.12825] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2013] [Revised: 03/17/2014] [Accepted: 04/24/2014] [Indexed: 11/29/2022]
Abstract
A structural model of human ferroportin has been built using two Escherichia coli proteins belonging to the major facilitator superfamily of transporters. A potential iron binding site was identified in the inward-open conformation of the model, and its relevance was tested through measurement of iron export of HEK293T cells expressing wild-type or mutated ferroportin. Aspartates 39 and 181 were found to be essential for the transport ability of the protein. Noteworthy, the D181V mutation is naturally found in type 4 hemochromatosis with reticuloendothelial system iron retention phenotype. The outward-open conformation of ferroportin was also predicted, and showed that significant conformational changes must occur in the inward- to outward-open transition of ferroportin. In particular, putative iron ligands move several ångströms away from each other, leading to the logical conclusion that the iron binding site is not occupied by the metal in the outward-open conformation of ferroportin.
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16
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Callebaut I, Joubrel R, Pissard S, Kannengiesser C, Gérolami V, Ged C, Cadet E, Cartault F, Ka C, Gourlaouen I, Gourhant L, Oudin C, Goossens M, Grandchamp B, De Verneuil H, Rochette J, Férec C, Le Gac G. Comprehensive functional annotation of 18 missense mutations found in suspected hemochromatosis type 4 patients. Hum Mol Genet 2014; 23:4479-90. [PMID: 24714983 DOI: 10.1093/hmg/ddu160] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Hemochromatosis type 4 is a rare form of primary iron overload transmitted as an autosomal dominant trait caused by mutations in the gene encoding the iron transport protein ferroportin 1 (SLC40A1). SLC40A1 mutations fall into two functional categories (loss- versus gain-of-function) underlying two distinct clinical entities (hemochromatosis type 4A versus type 4B). However, the vast majority of SLC40A1 mutations are rare missense variations, with only a few showing strong evidence of causality. The present study reports the results of an integrated approach collecting genetic and phenotypic data from 44 suspected hemochromatosis type 4 patients, with comprehensive structural and functional annotations. Causality was demonstrated for 10 missense variants, showing a clear dichotomy between the two hemochromatosis type 4 subtypes. Two subgroups of loss-of-function mutations were distinguished: one impairing cell-surface expression and one altering only iron egress. Additionally, a new gain-of-function mutation was identified, and the degradation of ferroportin on hepcidin binding was shown to probably depend on the integrity of a large extracellular loop outside of the hepcidin-binding domain. Eight further missense variations, on the other hand, were shown to have no discernible effects at either protein or RNA level; these were found in apparently isolated patients and were associated with a less severe phenotype. The present findings illustrate the importance of combining in silico and biochemical approaches to fully distinguish pathogenic SLC40A1 mutations from benign variants. This has profound implications for patient management.
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Affiliation(s)
- Isabelle Callebaut
- IMPMC, Sorbonne Universités - UMR CNRS 7590, UPMC Univ Paris 06, Muséum d'Histoire Naturelle, IRD UMR 206, Paris, France
| | - Rozenn Joubrel
- Laboratoire de Génétique Moléculaire et d'Histocompatibilité, Inserm U1078, Université de Brest, SFR SnInBioS, CHRU de Brest, Etablissement Français du Sang - Bretagne, Brest, France
| | - Serge Pissard
- Laboratoire de Génétique, UPEC (Université Paris Est Creteil), GHU Henri Mondor, Créteil, France
| | - Caroline Kannengiesser
- Hôpital Bichat, Département de Génétique, Inserm U1149 - Center for Research on Inflammation, Université Paris Diderot, AP-HP, Paris, France
| | | | - Cécile Ged
- Inserm U1035, Biothérapies des Maladies Génétiques et Cancers, Université de Bordeaux, CHU de Bordeaux, Pôle de Biologie et Pathologie, Bordeaux, France
| | - Estelle Cadet
- Laboratoire de Génétique Moléculaire, UPJV EA4666, CHU d'Amiens, Amiens, France
| | | | - Chandran Ka
- Laboratoire de Génétique Moléculaire et d'Histocompatibilité, Inserm U1078, Université de Brest, SFR SnInBioS, CHRU de Brest, Etablissement Français du Sang - Bretagne, Brest, France
| | - Isabelle Gourlaouen
- Laboratoire de Génétique Moléculaire et d'Histocompatibilité, Inserm U1078, Université de Brest, SFR SnInBioS, CHRU de Brest, Etablissement Français du Sang - Bretagne, Brest, France
| | | | - Claire Oudin
- Hôpital Bichat, Département de Génétique, Inserm U1149 - Center for Research on Inflammation, Université Paris Diderot, AP-HP, Paris, France
| | - Michel Goossens
- Laboratoire de Génétique, UPEC (Université Paris Est Creteil), GHU Henri Mondor, Créteil, France
| | - Bernard Grandchamp
- Hôpital Bichat, Département de Génétique, Inserm U1149 - Center for Research on Inflammation, Université Paris Diderot, AP-HP, Paris, France
| | - Hubert De Verneuil
- Inserm U1035, Biothérapies des Maladies Génétiques et Cancers, Université de Bordeaux, CHU de Bordeaux, Pôle de Biologie et Pathologie, Bordeaux, France
| | - Jacques Rochette
- Laboratoire de Génétique Moléculaire, UPJV EA4666, CHU d'Amiens, Amiens, France
| | - Claude Férec
- Laboratoire de Génétique Moléculaire et d'Histocompatibilité, Inserm U1078, Université de Brest, SFR SnInBioS, CHRU de Brest, Etablissement Français du Sang - Bretagne, Brest, France
| | - Gérald Le Gac
- Laboratoire de Génétique Moléculaire et d'Histocompatibilité, Inserm U1078, Université de Brest, SFR SnInBioS, CHRU de Brest, Etablissement Français du Sang - Bretagne, Brest, France CHRU de Brest, Inserm CIC0502, Brest, France
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17
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Abstract
The liver performs a large number of essential synthetic and regulatory functions that are acquired during fetal development and persist throughout life. Their disruption underlies a diverse group of heritable and acquired diseases that affect both pediatric and adult patients. Although experimental analyses used to study liver development and disease are typically performed in cell culture models or rodents, the zebrafish is increasingly used to complement discoveries made in these systems. Forward and reverse genetic analyses over the past two decades have shown that the molecular program for liver development is largely conserved between zebrafish and mammals, and that the zebrafish can be used to model heritable human liver disorders. Recent work has demonstrated that zebrafish can also be used to study the mechanistic basis of acquired liver diseases. Here, we provide a comprehensive summary of how the zebrafish has contributed to our understanding of human liver development and disease.
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Affiliation(s)
- Benjamin J Wilkins
- Department of Pathology and Laboratory Medicine, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
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18
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Le Gac G, Ka C, Joubrel R, Gourlaouen I, Lehn P, Mornon JP, Férec C, Callebaut I. Structure-function analysis of the human ferroportin iron exporter (SLC40A1): effect of hemochromatosis type 4 disease mutations and identification of critical residues. Hum Mutat 2013; 34:1371-80. [PMID: 23784628 DOI: 10.1002/humu.22369] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2013] [Accepted: 06/06/2013] [Indexed: 11/06/2022]
Abstract
Ferroportin (SLC40A1) is the only known iron exporter in mammals and is considered a key coordinator of the iron balance between intracellular and systemic iron homeostasis. However, the structural organization of ferroportin in the lipid bilayer remains controversial and very little is known about the mechanism underlying iron egress. In the present study, we have developed an approach based on comparative modeling, which has led to the construction of a model of the three-dimensional (3D) structure of ferroportin by homology to the crystal structure of a Major Facilitator Superfamily member (EmrD). This model predicts atomic details for the organization of ferroportin transmembrane helices and is in agreement with our current understanding of the ferroportin function and its interaction with hepcidin. Using in vitro experiments, we demonstrate that this model can be used to identify novel critical amino acids. In particular, we show that the tryptophan residue 42 (p.Trp42), which is localized within the extracellular end of the ferroportin pore, is likely involved in both the iron export function and in the mechanism of inhibition by hepcidin. Thus, our 3D model provides a new perspective for understanding the molecular basis of ferroportin functions and dysfunctions.
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Affiliation(s)
- Gérald Le Gac
- Inserm UMR1078, Université de Brest, SFR SnInBioS, Centre Hospitalier Régional Universitaire - Laboratoire de Génétique Moléculaire et d'Histocompatibilité, Etablissement Français du Sang - Bretagne, Brest, France
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19
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Abstract
Ferroportin (FPN) is the sole iron export membrane protein identified in mammals that is abundantly expressed on absorptive enterocytes and macrophages, and is essential for physiological regulation of cellular iron. The expression of FPN is positively induced by cellular iron and is suppressed by liver hepcidin in response to either increased systemic iron or inflammatory stimuli. Hepcidin binds to cell surface FPN inducing FPN internalization followed by lysosomal degradation of the protein and consequently iron efflux from macrophages is blocked and there is suboptimal iron absorption by duodenal enterocytes. Dozens of FPN gene mutations have been identified in different ethnic populations and some of the mutations are associated with autosomal dominant iron overload disorder described as FPN disease or hemochromatosis type 4 that is distinct from hereditary hemochromatosis due to HFE mutations. Clinical manifestations of iron overload FPN disease can be classified into two groups according to whether there is selective macrophage iron loading or parenchymal and reticuloendothelial iron accumulation. There is evidence suggesting that altered hepcidin-FPN interaction can modulate host's response to infection. Resistance to hepcidin promotes iron egress from cells and this inhibits growth of intracellular pathogens. Conversely, iron retention due to loss of iron export activity by mutated FPN results in intracellular iron accumulation and a permissive environment for intracellular pathogens.
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Affiliation(s)
- Ishmael Kasvosve
- Department of Medical Laboratory Sciences Faculty of Health Sciences, University of Botswana Private Bag UB 00712, Gaborone, Botswana.
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20
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Nekhai S, Xu M, Foster A, Kasvosve I, Diaz S, Machado RF, Castro OL, Kato GJ, Taylor JG, Gordeuk VR. Reduced sensitivity of the ferroportin Q248H mutant to physiological concentrations of hepcidin. Haematologica 2012; 98:455-63. [PMID: 23065513 DOI: 10.3324/haematol.2012.066530] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Ferroportin Q248H mutation has an allele frequency of 2.2-13.4% in African populations and is associated with a mild tendency to increased serum ferritin in the general population. Some investigators have reported that ferroportin Q248H is degraded after exposure to hepcidin in exactly the same manner as wild-type ferroportin, but supraphysiological concentrations of hepcidin were used. The aim of our study was to determine whether ferroportin Q248H may have reduced sensitivity to physiological concentrations of hepcidin. The sensitivity of ferroportin Q248H to hepcidin was determined in 293T cells transiently expressing ferroportin using immunoblotting and fluorescence analysis. Ferritin concentrations were measured in these cells and also in human primary monocytes derived from humans with different ferroportin genotypes. The effect of Q248H on serum iron measures was examined in patients with sickle cell anemia. Immunoblotting and fluorescence analysis showed decreased sensitivity of ferroportin Q248H to physiological concentrations of hepcidin. Lower ferritin concentrations were observed after incubation with iron and hepcidin in 293T cells expressing ferroportin Q248H and in primary monocytes from ferroportin Q248H subjects. In sickle cell anemia, ferroportin Q248H heterozygotes had lower serum ferritin concentrations than wild-type subjects, consistent with enhanced iron release by macrophage ferroportin Q248H. A clinical benefit of ferroportin Q248H was suggested by lower echocardiographic estimates of pulmonary artery pressure in patients carrying mutant alleles. In conclusion, our results suggest that ferroportin Q248H protein is resistant to physiological concentrations of hepcidin and that this mutation has discernible effects on iron metabolism-related clinical complications of sickle cell anemia. They provide a mechanistic explanation for the effect of ferroportin Q248H on iron status in individuals of African descent and suggest that these changes in iron metabolism may be beneficial under certain disease-specific circumstances. (ClinicalTrials.gov Identifier:NCT00011648).
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Affiliation(s)
- Sergei Nekhai
- Center for Sickle Cell Disease, Department of Medicine, Howard University, Washington, DC, USA.
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21
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Albuquerque D, Manco L, Loua KM, Arez AP, Trovoada MDJ, Relvas L, Millimono TS, Rath SL, Lopes D, Nogueira F, Varandas L, Alvarez M, Ribeiro ML. SLC40A1 Q248H allele frequencies and associated SLC40A1 haplotypes in three West African population samples. Ann Hum Biol 2011; 38:378-81. [PMID: 21231898 DOI: 10.3109/03014460.2010.541496] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
BACKGROUND Ferroportin is a transmembrane protein responsible for iron export from enterocytes and macrophages. Mutation c.744G → T (Q248H), located in exon 6 of the ferroportin gene SLC40A1, is found as a polymorphism in populations of African origin. This mutation has been extensively analysed in African-Americans, but poorly studied in native African populations. AIM To increase information about Q248H mutation frequency in native sub-Saharan populations examining three West African populations. SUBJECTS AND METHODS Samples from S. Tomé e Príncipe (n = 115), Angola (n = 156) and Republic of Guinea (n = 170) were analysed for Q248H mutation and for two polymorphisms, IVS1( - 24)G → C and microsatellite (CGG)(n), using standard molecular methodology. RESULTS The estimated frequencies of Q248H allele were 2.2% in S. Tomé e Príncipe, 3.5% in Angola and 4.1% in Republic of Guinea. Analysis of polymorphisms IVS1( - 24)G → C and (CGG)(n) showed mutation allele c.744T to be strongly associated with haplotype IVS1( - 24)G/(CGG)(7). CONCLUSIONS This study confirmed the presence of Q248H mutation at polymorphic frequencies in three native sub-Saharan populations. Analysis of two additional markers in the same gene support a single origin of the mutant allele c.744T in the haplotype background IVS1( - 24)G/(CGG)(7).
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22
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Le Lan C, Mosser A, Ropert M, Detivaud L, Loustaud-Ratti V, Vital-Durand D, Roget L, Bardou-Jacquet E, Turlin B, David V, Loréal O, Deugnier Y, Brissot P, Jouanolle AM. Sex and acquired cofactors determine phenotypes of ferroportin disease. Gastroenterology 2011; 140:1199-1207.e1-2. [PMID: 21199650 DOI: 10.1053/j.gastro.2010.12.049] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/23/2010] [Revised: 11/30/2010] [Accepted: 12/20/2010] [Indexed: 12/14/2022]
Abstract
BACKGROUND & AIMS Ferroportin disease is characterized by iron overload. It has an autosomal-dominant pattern of inheritance and has been associated with mutations in the SLC40A1 gene, which encodes the cellular iron exporter ferroportin. Since the first description in 2001, about 30 mutations have been reported; the heterogeneity of ferroportin disease phenotypes has led to the hypothesis that the nature of the mutation affects the function of the protein in different ways. We studied genotypes and phenotypes of a large cohort of patients with ferroportin disease. METHODS We studied clinical, biochemical, imaging, histologic, and genetic data from 70 affected subjects from 33 families with 19 mutations. RESULTS We found that ferroportin disease, at the time of diagnosis, has limited consequences in the absence of cofactors. Data indicated that transferrin saturation, which correlated with fibrosis and levels of alanine aminotransferase, might be a marker of disease severity. Although the study was performed in a large number of families, we observed incomplete penetrance and no correlation between genotypes and phenotypes. CONCLUSIONS Members of families with ferroportin disease should be screened for biochemical parameters of iron metabolism as well as genotype to detect silent mutations that might cause disease with acquired or genetic cofactors. Patients should be followed up long term to identify potential complications of the disease.
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Affiliation(s)
- Caroline Le Lan
- Service des Maladies du Foie, French Reference Centre for Rare Iron Overload Diseases of Genetic Origin and INSERM U-991, University Hospital Pontchaillou, Rennes, France
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23
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Host iron withholding demands siderophore utilization for Candida glabrata to survive macrophage killing. PLoS Pathog 2011; 7:e1001322. [PMID: 21445236 PMCID: PMC3060170 DOI: 10.1371/journal.ppat.1001322] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2010] [Accepted: 02/16/2011] [Indexed: 11/19/2022] Open
Abstract
The fungal pathogen Candida glabrata has risen from an innocuous commensal to a major human pathogen that causes life-threatening infections with an associated mortality rate of up to 50%. The dramatic rise in the number of immunocompromised individuals from HIV infection, tuberculosis, and as a result of immunosuppressive regimens in cancer treatment and transplant interventions have created a new and hitherto unchartered niche for the proliferation of C. glabrata. Iron acquisition is a known microbial virulence determinant and human diseases of iron overload have been found to correlate with increased bacterial burden. Given that more than 2 billion people worldwide suffer from iron deficiency and that iron overload is one of the most common single-gene inherited diseases, it is important to understand whether host iron status may influence C. glabrata infectious disease progression. Here we identify Sit1 as the sole siderophore-iron transporter in C. glabrata and demonstrate that siderophore-mediated iron acquisition is critical for enhancing C. glabrata survival to the microbicidal activities of macrophages. Within the Sit1 transporter, we identify a conserved extracellular SIderophore Transporter Domain (SITD) that is critical for siderophore-mediated ability of C. glabrata to resist macrophage killing. Using macrophage models of human iron overload disease, we demonstrate that C. glabrata senses altered iron levels within the phagosomal compartment. Moreover, Sit1 functions as a determinant for C. glabrata to survive macrophage killing in a manner that is dependent on macrophage iron status. These studies suggest that host iron status is a modifier of infectious disease that modulates the dependence on distinct mechanisms of microbial Fe acquisition. Candida glabrata is a major human pathogen due to its low susceptibility to conventional antifungal drugs and the dramatic increase in the number of immunocompromised individuals suffering from HIV AIDS, cancer, and diabetes. Iron overload is one of the most common genetically inherited diseases and reports suggest increased susceptibility of these patients to bacterial infection. The ability of microorganisms to obtain iron from their environment is a major determinant in their fitness and hence in their ability to cause infectious disease. Here we demonstrate that the siderophore iron carrier is critical for C. glabrata survival after ingestion by mouse and human macrophage immune effector cells. Through the generation of macrophage models of human iron overload disease we demonstrate that ingested C. glabrata cells sense altered macrophage iron levels, and that the Sit1 siderophore-iron transporter functions as a critical determinant in the ability of C. glabrata to survive macrophage killing in a manner that is dependent on macrophage iron status. Our results reveal a role for siderophore-iron as a source of iron during C. glabrata infection, suggest additional therapeutic intervention strategies, and support a pivotal contribution for a common human iron overload disease in the mechanisms used for Fe acquisition in C. glabrata.
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24
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Nevitt T. War-Fe-re: iron at the core of fungal virulence and host immunity. Biometals 2011; 24:547-58. [PMID: 21399939 DOI: 10.1007/s10534-011-9431-8] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2011] [Accepted: 02/22/2011] [Indexed: 12/21/2022]
Abstract
Iron acquisition is a bona fide virulence determinant. The successful colonization of the mammalian host requires that microorganisms overcome the Fe aridity of this milieu in which the levels of circulating Fe are maintained exceedingly low both through the compartmentalization of this nutrient within cells as well as the tight binding of Fe to host circulating proteins and ligands. Microbes notoriously employ multiple strategies for high affinity Fe acquisition from the host that rely either on the expression of receptors for host Fe-binding proteins and ligands, its reduction by cell surface reductases or the utilization of siderophores, small organic molecules with very high affinity for Fe(3+). This review will discuss the multiple mechanisms deployed by fungal pathogens in Fe acquisition focusing on the role of siderophore utilization in virulence as well as host immune strategies of iron withholding and emerging clinical evidence that human disorders of Fe homeostasis can act as modifiers of infectious disease.
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Affiliation(s)
- Tracy Nevitt
- Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, NC 27710, USA.
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25
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Ferroportin disease: a systematic meta-analysis of clinical and molecular findings. J Hepatol 2010; 53:941-9. [PMID: 20691492 PMCID: PMC2956830 DOI: 10.1016/j.jhep.2010.05.016] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/19/2009] [Revised: 05/09/2010] [Accepted: 05/15/2010] [Indexed: 01/01/2023]
Abstract
BACKGROUND & AIMS Classical ferroportin disease is characterized by hyperferritinemia, normal transferrin saturation, and iron overload in macrophages. A non-classical form is characterized by additional hepatocellular iron deposits and a high transferrin saturation. Both forms demonstrate autosomal dominant transmission and are associated with ferroportin gene (SLC40A1) mutations. SLC40A1 encodes a cellular iron exporter expressed in macrophages, enterocytes, and hepatocytes. The aim of the analysis is to determine the penetrance of SLC40A1 mutations and to evaluate in silico tools to predict the functional impairment of ferroportin mutations as an alternative to in vitro studies. METHODS We conducted a systematic review of the literature and meta-analysis of the biochemical presentation, genetics, and pathology of ferroportin disease. RESULTS Of the 176 individuals reported with SLC40A1 mutations, 80 were classified as classical phenotype with hyperferritinemia and normal transferrin saturation. The non-classical phenotype with hyperferritinemia and elevated transferrin saturation was present in 53 patients. The remaining patients had normal serum ferritin or the data were reported incompletely. Despite an increased hepatic iron concentration in all biopsied patients, significant fibrosis or cirrhosis was present in only 11%. Hyperferritinemia was present in 86% of individuals with ferroportin mutations. Bio-informatic analysis of ferroportin mutations showed that the PolyPhen score has a sensitivity of 99% and a specificity of 67% for the discrimination between ferroportin mutations and polymorphisms. CONCLUSIONS In contrast to HFE hemochromatosis, ferroportin disease has a high penetrance, is genetically heterogeneous and is rarely associated with fibrosis. Non-classical ferroportin disease is associated with a higher risk of fibrosis and a more severe overload of hepatic iron.
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Evaluation of hepcidin isoforms in hemodialysis patients by a proteomic approach based on SELDI-TOF MS. J Biomed Biotechnol 2010; 2010:329646. [PMID: 20414466 PMCID: PMC2857619 DOI: 10.1155/2010/329646] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2009] [Revised: 11/06/2009] [Accepted: 02/10/2010] [Indexed: 12/18/2022] Open
Abstract
The hepatic iron regulator hormone hepcidin consists, in its mature form, of 25 amino acids, but two other isoforms, hepcidin-20 and hepcidin-22, have been reported, whose biological meaning remains poorly understood. We evaluated hepcidin isoforms in sera from 57 control and 54 chronic haemodialysis patients using a quantitative proteomic approach based on SELDI-TOF-MS. Patients had elevated serum levels of both hepcidin-25 and hepcidin-20 as compared to controls (geometric means: 7.52 versus 4.69 nM, and 4.06 versus 1.76 nM, resp., P < .05 for both). The clearance effects of a single dialysis session by different dialysis techniques and membranes were also investigated, showing an average reduction by 51.3% +/- 29.2% for hepcidin-25 and 34.2% +/- 28.4% for hepcidin-20 but only minor differences among the different dialysis modalities. Measurement of hepcidin isoforms through MS-based techniques can be a useful tool for better understanding of their biological role in hemodialysis patients and other clinical conditions.
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Recalcati S, Locati M, Marini A, Santambrogio P, Zaninotto F, De Pizzol M, Zammataro L, Girelli D, Cairo G. Differential regulation of iron homeostasis during human macrophage polarized activation. Eur J Immunol 2010; 40:824-35. [DOI: 10.1002/eji.200939889] [Citation(s) in RCA: 288] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Griffiths WJH, Mayr R, McFarlane I, Hermann M, Halsall DJ, Zoller H, Cox TM. Clinical presentation and molecular pathophysiology of autosomal dominant hemochromatosis caused by a novel ferroportin mutation. Hepatology 2010; 51:788-95. [PMID: 19937651 DOI: 10.1002/hep.23377] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/07/2022]
Abstract
UNLABELLED Mutations in the SLC40A1 gene, which encodes ferroportin, are associated with autosomal dominant hemochromatosis. Ferroportin is inhibited directly by hepcidin, a key iron-regulatory peptide, and functional consequences of SLC40A1 mutations account for observed phenotypic differences in patients with ferroportin disease. We describe a large pedigree with a novel SLC40A1 mutation and, through in vitro analysis, elucidate the associated molecular mechanism of iron overload. The entire coding sequence of the SLC40A1 gene was sequenced in a pedigree, presenting with autosomal dominant hyperferritinemia. The functional effects of a novel SLC40A1 mutation were studied by overexpression of wild-type and mutant ferroportin fusion proteins in human embryonic kidney cells. Iron export was studied in these cells using (59)Fe transport assays; subcellular localization of ferroportin was examined by way of confocal microscopy. A novel SLC40A1 mutation p.R489K segregated with iron overload in a family with clinical and histopathological signs of macrophage-type ferroportin disease. Human embryonic kidney cells overexpressing p.R489K ferroportin showed decreased iron export capacity when compared with wild-type ferroportin overexpressing cells. Subcellular localization studies demonstrated that p.R489K ferroportin was retained abnormally within an intracellular compartment. CONCLUSION We report a novel pathological SLC40A1 variant associated with abnormal cell surface expression of ferroportin due to intracellular retention of the mutant protein. These findings predict macrophage-type ferroportin disease, the phenotype observed in this kindred. Study of the molecular cell biology of ferroportin and its mutants is key to understanding the pathogenesis of this increasingly recognized form of hemochromatosis, which responds poorly to conventional therapy.
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Affiliation(s)
- William J H Griffiths
- Department of Hepatology, Box 210, Cambridge University Hospitals NHS Foundation Trust, Hills Road, Cambridge CB2 0QQ, UK.
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Castagna A, Campostrini N, Zaninotto F, Girelli D. Hepcidin assay in serum by SELDI-TOF-MS and other approaches. J Proteomics 2009; 73:527-36. [PMID: 19683083 DOI: 10.1016/j.jprot.2009.08.003] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2009] [Accepted: 08/05/2009] [Indexed: 01/01/2023]
Abstract
Hepcidin, a liver peptide hormone, is the central regulator of iron homeostasis. Hepcidin synthesis is modulated by iron stores, so that iron repletion increases its levels to prevent pathological overload, while iron deficiency strongly inhibits hepcidin to allow an increase in iron absorption from duodenal cells. The emerging pivotal role of hepcidin in iron homeostasis, along with its important links with basic pathways like inflammation, makes the availability of an accurate hepcidin assay as a potentially powerful investigative tool to improve our understanding as well as our diagnostic/prognostic capabilities in many human diseases. There has been a great interest worldwide in developing a reliable and widely applicable assay of the hormone in biological fluids. Being optimal for low-molecular-weight biomarkers, SELDI-TOF-MS has emerged as a valid tool for hepcidin assay. Here we review recent results obtained with this technique, as well as with other Mass Spectrometry-based and immunological methods.
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Affiliation(s)
- Annalisa Castagna
- Department of Clinical and Experimental Medicine, University of Verona, Verona, Italy.
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Abstract
There have been major developments in the field of iron metabolism in the past decade following the identification of the HFE gene and the mutation responsible for the C282Y substitution in the HFE protein. While HFE-associated hemochromatosis occurs predominantly in people of northern European extraction, other less-common mutations can lead to the same clinical syndrome and these may occur in other populations in the Asian-Pacific region. The most common of these is the mutation that leads to changes in the ferroportin molecule, the protein responsible for the transport of iron across the basolateral membrane of the enterocyte and from macrophages. Recent research has unraveled the molecular processes of iron transport and regulation of how these are disturbed in hemochromatosis and other iron-loading disorders. At the same time, at least one new oral iron chelating agent has been developed that shows promise in the therapy of hemochromatosis as well as thalassemia and other secondary causes of iron overload. It is pertinent therefore to examine the developments in the global field of iron overload that have provided insights into the pathogenesis, disease penetrance, comorbid factors, and management.
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Nramp1 promotes efficient macrophage recycling of iron following erythrophagocytosis in vivo. Proc Natl Acad Sci U S A 2009; 106:5960-5. [PMID: 19321419 DOI: 10.1073/pnas.0900808106] [Citation(s) in RCA: 112] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Natural resistance-associated macrophage protein 1 (Nramp1) is a divalent metal transporter expressed exclusively in phagocytic cells. We hypothesized that macrophage Nramp1 may participate in the recycling of iron acquired from phagocytosed senescent erythrocytes. To evaluate the role of Nramp1 in vivo, the iron parameters of WT and KO mice were analyzed after acute and chronic induction of hemolytic anemia. We found that untreated KO mice exhibited greater serum transferrin saturation and splenic iron content with higher duodenal ferroportin (Fpn) and divalent metal transporter 1 (DMT1) expression. Furthermore, hepatocyte iron content and hepcidin mRNA levels were dramatically lower in KO mice, indicating that hepcidin levels can be regulated by low-hepatocyte iron stores despite increased transferrin saturation. After acute treatment with the hemolytic agent phenylhydrazine (Phz), KO mice experienced a significant decrease in transferrin saturation and hematocrit, whereas WT mice were relatively unaffected. After a month-long Phz regimen, KO mice retained markedly increased quantities of iron within the liver and spleen and exhibited more pronounced splenomegaly and reticulocytosis than WT mice. After injection of (59)Fe-labeled heat-damaged reticulocytes, KO animals accumulated erythrophagocytosed (59)Fe within their liver and spleen, whereas WT animals efficiently recycled phagocytosed (59)Fe to the marrow and erythrocytes. These data imply that without Nramp1, iron accumulates within the liver and spleen during erythrophagocytosis and hemolytic anemia, supporting our hypothesis that Nramp1 promotes efficient hemoglobin iron recycling in macrophages. Our observations suggest that mutations in Nramp1 could result in a novel form of human hereditary iron overload.
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