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Clinical and Molecular Aspects of Iron Metabolism in Failing Myocytes. LIFE (BASEL, SWITZERLAND) 2022; 12:life12081203. [PMID: 36013382 PMCID: PMC9409945 DOI: 10.3390/life12081203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Revised: 07/15/2022] [Accepted: 07/22/2022] [Indexed: 11/16/2022]
Abstract
Heart failure (HF) is a common disease that causes significant limitations on the organism's capacity and, in extreme cases, leads to death. Clinically, iron deficiency (ID) plays an essential role in heart failure by deteriorating the patient's condition and is a prognostic marker indicating poor clinical outcomes. Therefore, in HF patients, supplementation of iron is recommended. However, iron treatment may cause adverse effects by increasing iron-related apoptosis and the production of oxygen radicals, which may cause additional heart damage. Furthermore, many knowledge gaps exist regarding the complex interplay between iron deficiency and heart failure. Here, we describe the current, comprehensive knowledge about the role of the proteins involved in iron metabolism. We will focus on the molecular and clinical aspects of iron deficiency in HF. We believe that summarizing the new advances in the translational and clinical research regarding iron deficiency in heart failure should broaden clinicians' awareness of this comorbidity.
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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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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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Deng Z, Manz DH, Torti SV, Torti FM. Effects of Ferroportin-Mediated Iron Depletion in Cells Representative of Different Histological Subtypes of Prostate Cancer. Antioxid Redox Signal 2019; 30:1043-1061. [PMID: 29061069 PMCID: PMC6354616 DOI: 10.1089/ars.2017.7023] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
AIMS Ferroportin (FPN) is an iron exporter that plays an important role in cellular and systemic iron metabolism. Our previous work has demonstrated that FPN is decreased in prostate tumors. We sought to identify the molecular pathways regulated by FPN in prostate cancer cells. RESULTS We show that overexpression of FPN induces profound effects in cells representative of multiple histological subtypes of prostate cancer by activating different but converging pathways. Induction of FPN induces autophagy and activates the transcription factors tumor protein 53 (p53) and Kruppel-like factor 6 (KLF6) and their common downstream target, cyclin-dependent kinase inhibitor 1A (p21). FPN also induces cell cycle arrest and stress-induced DNA-damage genes. Effects of FPN are attributable to its effects on intracellular iron and can be reproduced with iron chelators. Importantly, expression of FPN not only inhibits proliferation of all prostate cancer cells studied but also reduces growth of tumors derived from castrate-resistant adenocarcinoma C4-2 cells in vivo. INNOVATION We use a novel model of FPN expression to interrogate molecular pathways triggered by iron depletion in prostate cancer cells. Since prostate cancer encompasses different subtypes with a highly variable clinical course, we further explore how histopathological subtype influences the response to iron depletion. We demonstrate that prostate cancer cells that derive from different histopathological subtypes activate converging pathways in response to FPN-mediated iron depletion. Activation of these pathways is sufficient to significantly reduce the growth of treatment-refractory C4-2 prostate tumors in vivo. CONCLUSIONS Our results may explain why FPN is dramatically suppressed in cancer cells, and they suggest that FPN agonists may be beneficial in the treatment of prostate cancer.
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Affiliation(s)
- Zhiyong Deng
- 1 Department of Molecular Biology and Biophysics, UCONN Health, Farmington, Connecticut
| | - David H Manz
- 1 Department of Molecular Biology and Biophysics, UCONN Health, Farmington, Connecticut.,2 School of Dental Medicine, UCONN Health, Farmington, Connecticut
| | - Suzy V Torti
- 1 Department of Molecular Biology and Biophysics, UCONN Health, Farmington, Connecticut
| | - Frank M Torti
- 3 Department of Medicine, UCONN Health, Farmington, Connecticut
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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: 83] [Impact Index Per Article: 11.9] [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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Sabelli M, Montosi G, Garuti C, Caleffi A, Oliveto S, Biffo S, Pietrangelo A. Human macrophage ferroportin biology and the basis for the ferroportin disease. Hepatology 2017; 65:1512-1525. [PMID: 28027576 PMCID: PMC5413859 DOI: 10.1002/hep.29007] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Accepted: 12/15/2016] [Indexed: 01/01/2023]
Abstract
Ferroportin (FPN1) is the sole iron exporter in mammals, but its cell-specific function and regulation are still elusive. This study examined FPN1 expression in human macrophages, the cells that are primarily responsible on a daily basis for plasma iron turnover and are central in the pathogenesis of ferroportin disease (FD), the disease attributed to lack-of-function FPN1 mutations. We characterized FPN1 protein expression and traffic by confocal microscopy, western blotting, gel filtration, and immunoprecipitation studies in macrophages from control blood donors (donor) and patients with either FPN1 p.A77D, p.G80S, and p.Val162del lack-of-function or p.A69T gain-of-function mutations. We found that in normal macrophages, FPN1 cycles in the early endocytic compartment does not multimerize and is promptly degraded by hepcidin (Hepc), its physiological inhibitor, within 3-6 hours. In FD macrophages, endogenous FPN1 showed a similar localization, except for greater accumulation in lysosomes. However, in contrast with previous studies using overexpressed mutant protein in cell lines, FPN1 could still reach the cell surface and be normally internalized and degraded upon exposure to Hepc. However, when FD macrophages were exposed to large amounts of heme iron, in contrast to donor and p.A69T macrophages, FPN1 could no longer reach the cell surface, leading to intracellular iron retention. CONCLUSION FPN1 cycles as a monomer within the endocytic/plasma membrane compartment and responds to its physiological inhibitor, Hepc, in both control and FD cells. However, in FD, FPN1 fails to reach the cell surface when cells undergo high iron turnover. Our findings provide a basis for the FD characterized by a preserved iron transfer in the enterocytes (i.e., cells with low iron turnover) and iron retention in cells exposed to high iron flux, such as liver and spleen macrophages. (Hepatology 2017;65:1512-1525).
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Affiliation(s)
- Manuela Sabelli
- Division of Internal Medicine 2 and Center for HemochromatosisUniversity Hospital of ModenaModenaItaly
| | - Giuliana Montosi
- Division of Internal Medicine 2 and Center for HemochromatosisUniversity Hospital of ModenaModenaItaly
| | - Cinzia Garuti
- Division of Internal Medicine 2 and Center for HemochromatosisUniversity Hospital of ModenaModenaItaly
| | - Angela Caleffi
- Division of Internal Medicine 2 and Center for HemochromatosisUniversity Hospital of ModenaModenaItaly
| | | | - Stefano Biffo
- INGM, ‘Romeo ed Enrica Invernizzi’MilanoItaly
- Department of BiosciencesUniversity of MilanMilanItaly
| | - Antonello Pietrangelo
- Division of Internal Medicine 2 and Center for HemochromatosisUniversity Hospital of ModenaModenaItaly
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Bardou-Jacquet E, Ben Ali Z, Beaumont-Epinette MP, Loreal O, Jouanolle AM, Brissot P. Non-HFE hemochromatosis: pathophysiological and diagnostic aspects. Clin Res Hepatol Gastroenterol 2014; 38:143-54. [PMID: 24321703 DOI: 10.1016/j.clinre.2013.11.003] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/20/2013] [Revised: 11/04/2013] [Accepted: 11/13/2013] [Indexed: 02/04/2023]
Abstract
Rare genetic iron overload diseases are an evolving field due to major advances in genetics and molecular biology. Genetic iron overload has long been confined to the classical type 1 hemochromatosis related to the HFE C282Y mutation. Breakthroughs in the understanding of iron metabolism biology and molecular mechanisms led to the discovery of new genes and subsequently, new types of hemochromatosis. To date, four types of hemochromatosis have been identified: HFE-related or type1 hemochromatosis, the most frequent form in Caucasians, and four rare types, named type 2 (A and B) hemochromatosis (juvenile hemochromatosis due to hemojuvelin and hepcidin mutation), type 3 hemochromatosis (related to transferrin receptor 2 mutation), and type 4 (A and B) hemochromatosis (ferroportin disease). The diagnosis relies on the comprehension of the involved physiological defect that can now be explored by biological and imaging tools, which allow non-invasive assessment of iron metabolism. A multidisciplinary approach is essential to support the physicians in the diagnosis and management of those rare diseases.
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Affiliation(s)
- Edouard Bardou-Jacquet
- University Hospital of Rennes, French reference center for rare iron overload diseases of genetic origin, Rennes, France; University of Rennes1, Inserm UMR 991, 35000 Rennes, France; University Hospital of Rennes, Liver disease department, Rennes, France.
| | - Zeineb Ben Ali
- University Hospital of Rennes, French reference center for rare iron overload diseases of genetic origin, Rennes, France; University Hospital of Rennes, Liver disease department, Rennes, France
| | - Marie-Pascale Beaumont-Epinette
- University Hospital of Rennes, French reference center for rare iron overload diseases of genetic origin, Rennes, France; University Hospital of Rennes, Molecular Genetics Department, Rennes, France
| | - Olivier Loreal
- University Hospital of Rennes, French reference center for rare iron overload diseases of genetic origin, Rennes, France; University of Rennes1, Inserm UMR 991, 35000 Rennes, France
| | - Anne-Marie Jouanolle
- University Hospital of Rennes, French reference center for rare iron overload diseases of genetic origin, Rennes, France; University Hospital of Rennes, Molecular Genetics Department, Rennes, France
| | - Pierre Brissot
- University Hospital of Rennes, French reference center for rare iron overload diseases of genetic origin, Rennes, France; University of Rennes1, Inserm UMR 991, 35000 Rennes, France; University Hospital of Rennes, Liver disease department, Rennes, France
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McDonald CJ, Wallace DF, Crawford DHG, Subramaniam VN. Iron storage disease in Asia-Pacific populations: the importance of non-HFE mutations. J Gastroenterol Hepatol 2013; 28:1087-94. [PMID: 23577916 DOI: 10.1111/jgh.12222] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 04/03/2013] [Indexed: 01/24/2023]
Abstract
Hereditary hemochromatosis (HH) is a widely recognized and well-studied condition in European populations. This is largely due to the high prevalence of the C282Y mutation of HFE. Although less common than in Europe, HH cases have been reported in the Asia-Pacific region because of mutations in both HFE and non-HFE genes. Mutations in all of the currently known genes implicated in non-HFE HH (hemojuvelin, hepcidin, transferrin receptor 2, and ferroportin) have been reported in patients from the Asia-Pacific region. This review discusses the molecular basis of HH and the genes and mutations known to cause non-HFE HH with particular reference to the Asia-Pacific region. Challenges in the genetic diagnosis of non-HFE HH are also discussed and how new technologies such as next generation sequencing may be informative in the future.
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Affiliation(s)
- Cameron J McDonald
- The Membrane Transport Laboratory, The Queensland Institute of Medical Research, Brisbane, Queensland, Australia
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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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Brissot P, Troadec MB, Bardou-Jacquet E, Le Lan C, Jouanolle AM, Deugnier Y, Loréal O. Current approach to hemochromatosis. Blood Rev 2008; 22:195-210. [PMID: 18430498 DOI: 10.1016/j.blre.2008.03.001] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Iron overload diseases of genetic origin are an ever changing world, due to major advances in genetics and molecular biology. Five major categories are now established: HFE-related or type1 hemochromatosis, frequently found in Caucasians, and four rarer diseases which are type 2 (A and B) hemochromatosis (juvenile hemochromatosis), type 3 hemochromatosis (transferrin receptor 2 hemochromatosis), type 4 (A and B) hemochromatosis (ferroportin disease), and a(hypo)ceruloplasminemia. Increased duodenal iron absorption and enhanced macrophagic iron recycling, both due to an impairment of hepcidin synthesis, account for the development of cellular excess in types 1, 2, 3, and 4B hemochromatosis whereas decreased cellular iron egress is involved in the main form of type 4A) hemochromatosis and in aceruloplasminemia. Non-transferrin bound iron plays an important role in cellular iron excess and damage. The combination of magnetic resonance imaging (for diagnosing visceral iron overload) and of genetic testing has drastically reduced the need for liver biopsy. Phlebotomies remain an essential therapeutic tool but the improved understanding of the intimate mechanisms underlying these diseases paves the road for innovative therapeutic approaches.
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Affiliation(s)
- Pierre Brissot
- Liver Disease Unit, Liver Research Unit Inserm U-522, IFR 140, University of Rennes1, Hemochromatosis Reference Center, Laboratory of Molecular Genetics, University Hospital Pontchaillou, Rennes, France.
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Pelucchi S, Mariani R, Salvioni A, Bonfadini S, Riva A, Bertola F, Trombini P, Piperno A. Novel mutations of the ferroportin gene (SLC40A1): analysis of 56 consecutive patients with unexplained iron overload. Clin Genet 2007; 73:171-8. [DOI: 10.1111/j.1399-0004.2007.00950.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Lim FL, Dooley JS, Roques AW, Grellier L, Dhillon AP, Walker AP. Hepatic iron concentration, fibrosis and response to venesection associated with the A77D and V162del "loss of function" mutations in ferroportin disease. Blood Cells Mol Dis 2007; 40:328-33. [PMID: 18160317 DOI: 10.1016/j.bcmd.2007.11.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2007] [Revised: 11/13/2007] [Accepted: 11/16/2007] [Indexed: 12/13/2022]
Abstract
Ferroportin disease is an autosomal dominant form of hemochromatosis associated with siderosis in cells of the mononuclear phagocyte system and, to varying degrees, in hepatocytes. Ferroportin was investigated as a candidate gene in two pedigrees with hyperferritinaemia and siderosis in mononuclear phagocytes. The entire ferroportin coding region was sequenced and hepatic iron concentration, histology and response to treatment were determined. The results were compared with previously reported cases. The A77D mutation was detected in patient 1, his father (patient 2) and his brother (patient 3), who had portal fibrosis. The V162del mutation was detected in patient 4, who developed anemia after the third weekly venesection. While the disease is rare, A77D and V162del are the most common ferroportin mutations in Caucasians. The spectrum of clinical expression of these two mutations was reviewed in all cases described to date. These mutations were associated with fibrosis in about a third of cases. For A77D and V162del, this analysis confirms that the threshold hepatic iron concentration for development of fibrosis may be higher than for classical hemochromatosis. These two mutations, which both decreased iron export in cell culture studies, give rise to similar patterns of clinical expression and morbidity, although the highest hepatic iron concentrations have been observed with A77D. It is important for clinicians to consider ferroportin disease in cases where there are features of iron overload unrelated to HFE, autosomal dominant inheritance and/or iron deposition in mononuclear phagocytes.
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Affiliation(s)
- Francesca L Lim
- Centre for Molecular Medicine, Department of Medicine, The Rayne Institute, University College London, 5 University Street, London, WC1E 6JF, UK
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Abstract
Non-HFE hereditary haemochromatosis (HH) refers to a genetically heterogeneous group of iron overload disorders that are unlinked to mutations in the HFE gene. The four main types of non-HFE HH are caused by mutations in the hemojuvelin, hepcidin, transferrin receptor 2 and ferroportin genes. Juvenile haemochromatosis is an autosomal recessive disorder and can be caused by mutations in either hemojuvelin or hepcidin. An adult onset form of HH similar to HFE-HH is caused by homozygosity for mutations in transferrin receptor 2. The autosomal dominant iron overload disorder ferroportin disease is caused by mutations in the iron exporter ferroportin. The clinical characteristics and molecular basis of the various types of non-HFE haemochromatosis are reviewed. The study of these disorders and the molecules involved has been invaluable in improving our understanding of the mechanisms involved in the regulation of iron metabolism.
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Affiliation(s)
- Daniel-F Wallace
- Membrane Transport Laboratory, The Queensland Institute of Medical Research, 300 Herston Road, Herston, Brisbane, QLD 4006 Australia
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Pietrangelo A, Corradini E, Ferrara F, Vegetti A, De Jong G, Luca Abbati G, Paolo Arcuri P, Martinelli S, Cerofolini E. Magnetic resonance imaging to identify classic and nonclassic forms of ferroportin disease. Blood Cells Mol Dis 2006; 37:192-6. [PMID: 17052926 DOI: 10.1016/j.bcmd.2006.08.007] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2006] [Revised: 08/30/2006] [Accepted: 08/30/2006] [Indexed: 12/25/2022]
Abstract
The ferroportin-related disorder is an increasingly recognized cause of hereditary iron overload. Based on the in vitro behavior of different ferroportin mutant subsets, it was suggested that different forms of the disorder might exist in humans. We used MRI to address this question in vivo in 22 patients from four different pedigrees carrying different ferroportin mutations: A77D, N144H, G80S and Val 162del. We found that, based on the iron status of spleen and bone macrophages, two different forms of the disease can be identified: a classic, common form, characterized by hepatocyte, splenic macrophage and bone marrow macrophage iron retention in patients carrying the A77D, G80S and Val 162del ferroportin variants; a rarer non-classic form, associated with liver iron overload but normal spleen and bone marrow iron content in patients with the N144H mutation. The two forms are likely caused by lack- or gain-of-protein function, respectively. Interestingly, in treated patients with the classic form, the spleen and the spine show appreciable iron accumulation even when serum ferritin is normal and liver iron content low. In conclusion, MRI is a useful non-invasive diagnostic tool to categorize and diagnose the disorder, monitor the status of iron depletion and gain insights on its natural history and management.
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Affiliation(s)
- Antonello Pietrangelo
- Center for Hemochromatosis, Department of Internal Medicine, University Hospital of Modena and Reggio Emilia, Policlinico, Via del Pozzo 71 41100 Modena, Italy.
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15
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Abstract
Hepcidin evolves as a potent hepatocyte-derived regulator of the body's iron distribution piloting the flow of iron via, and directly binding, to the cellular iron exporter ferroportin. The hepcidin-ferroportin axis dominates the iron egress from all cellular compartments that are critical to iron homeostasis, namely placental syncytiotrophoblasts, duodenal enterocytes, hepatocytes and macrophages of the reticuloendothelial system. The gene that encodes hepcidin expression (HAMP) is subject to regulation by proinflammatory cytokines, such as IL-6 and IL-1; excessive hepcidin production explains the relative deficiency of iron during inflammatory states, eventually resulting in the anaemia of inflammation. The haemochromatosis genes HFE, TfR2 and HJV potentially facilitate the transcription of HAMP. Disruption of each of the four genes leads to a diminished hepatic release of hepcidin consistent with both a dominant role of hepcidin in hereditary haemochromatosis and an upstream regulatory role of HFE, TfR2 and HJV on HAMP expression. The engineered generation of hepcidin agonists, mimetics or antagonists could largely broaden current therapeutic strategies to redirect the flow of iron.
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Affiliation(s)
- R Deicher
- Department of Medicine III, Medical University of Vienna, Vienna, Austria
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Cremonesi L, Cemonesi L, Forni GL, Soriani N, Lamagna M, Fermo I, Daraio F, Galli A, Pietra D, Malcovati L, Ferrari M, Camaschella C, Cazzola M. Genetic and clinical heterogeneity of ferroportin disease. Br J Haematol 2005; 131:663-70. [PMID: 16351644 DOI: 10.1111/j.1365-2141.2005.05815.x] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Ferroportin is encoded by the SLC40A1 gene and mediates iron export from cells by interacting with hepcidin. SLC40A1 gene mutations are associated with an autosomal type of genetic iron overload described as haemochromatosis type 4, or HFE4 (Online Mendelian Inheritance in Man number 606069), or ferroportin disease. We report three families with this condition caused by novel SLC40A1 mutations. Denaturing high-performance liquid chromatography was employed to scan for the SLC40A1 gene. A D181V (A846T) mutation in exon 6 of the ferroportin gene was detected in the affected members of an Italian family and shown to have a de novo origin in a maternal germinal line. This mutation was associated with both parenchymal and reticuloendothelial iron overload in the liver, and with reduced urinary hepcidin excretion. A G80V (G543T) mutation in exon 3 was found in the affected members of an Italian family with autosomal hyperferritinaemia,. Finally, a G267D (G1104A) mutation was identified in exon 7 in a family of Chinese descent whose members presented with isolated hyperferritinaemia. Ferroportin disease represents a protean genetic condition in which the different SLC40A1 mutations appear to be responsible for phenotypic variability. This condition should be considered not only in families with autosomal iron overload or hyperferritinaemia, but also in cases of unexplained hyperferritinaemia.
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Affiliation(s)
- L Cremonesi
- Unit of Genomics for the Diagnosis of Human Pathologies, IRCCS H. San Raffaele, Milan, Italy
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Morris TJ, Litvinova MM, Ralston D, Mattman A, Holmes D, Lockitch G. A novel ferroportin mutation in a Canadian family with autosomal dominant hemochromatosis. Blood Cells Mol Dis 2005; 35:309-14. [PMID: 16111902 DOI: 10.1016/j.bcmd.2005.07.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2005] [Accepted: 07/18/2005] [Indexed: 12/19/2022]
Abstract
We report a new mutation, Asn185Asp, in exon 6 of the ferroportin gene (FPN1) in 15 members of three successive generations of a Canadian family of Scandinavian origin with autosomal dominant hemochromatosis. Hyperferritinemia with low transferrin saturation was noted in younger family members, seven of whom were aged 20 years or less at the time of diagnosis. In those individuals first diagnosed with hemochromatosis in later life, marked hyperferritinemia was accompanied by high transferrin saturation. In contrast to the phenotype of high ferritin with low saturation first reported for ferroportin disease, this family demonstrates a phenotype of iron indices that varies with age.
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Affiliation(s)
- Tara J Morris
- Department of Pathology and Laboratory Medicine, Children's and Women's Health Centre of British Columbia, 4480 Oak Street, Vancouver, Canada BC V6H3V4
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