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Abstract
Hepcidin, the main regulator of iron metabolism, is synthesized and released by hepatocytes in response to increased body iron concentration and inflammation. Deregulation of hepcidin expression is a common feature of genetic and acquired iron disorders: in Hereditary Hemochromatosis (HH) and iron-loading anemias low hepcidin causes iron overload, while in Iron Refractory Iron Deficiency Anemia (IRIDA) and anemia of inflammation (AI), high hepcidin levels induce iron-restricted erythropoiesis. Hepcidin expression in the liver is mainly controlled by the BMP-SMAD pathway, activated in a paracrine manner by BMP2 and BMP6 produced by liver sinusoidal endothelial cells. The BMP type I receptors ALK2 and ALK3 are responsible for iron-dependent hepcidin upregulation and basal hepcidin expression, respectively. Characterization of animal models with genetic inactivation of the key components of the pathway has suggested the existence of two BMP/SMAD pathway branches: the first ALK3 and HH proteins dependent, responsive to BMP2 for basal hepcidin activation, and the second ALK2 dependent, activated by BMP6 in response to increased tissue iron. The erythroid inhibitor of hepcidin Erythroferrone also impacts on the liver BMP-SMAD pathway although its effect is blunted by pathway hyper-activation. The liver BMP-SMAD pathway is required also in inflammation to cooperate with JAK2/STAT3 signaling for full hepcidin activation. Pharmacologic targeting of BMP-SMAD pathway components or regulators may improve the outcome of both genetic and acquired disorders of iron overload and deficiency by increasing or inhibiting hepcidin expression.
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52
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Santos-Silva A, Ribeiro S, Reis F, Belo L. Hepcidin in chronic kidney disease anemia. VITAMINS AND HORMONES 2019; 110:243-264. [PMID: 30798815 DOI: 10.1016/bs.vh.2019.01.012] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Chronic kidney disease (CKD) is associated with several complications that worsen with progression of disease; anemia, disturbances in iron metabolism and inflammation are common features. Inflammatory response starts early, releasing pro-inflammatory cytokines, acute phase reactants and hepcidin. Hepcidin production is modulated by several factors, as hypoxia/anemia, erythropoietin and erythropoiesis products, transferrin saturation (TSAT) and liver iron levels, which are altered in CKD. Treatment of CKD anemia is based on pharmaceutical intervention, with erythropoietic stimulating agents and/or iron supplementation; however, in spite of the erythropoietic benefits, this therapy, on a regular basis, involves risks, namely iron overload. To overcome these risks, some therapeutic approaches are under study to target CKD anemia. Considering the actual alerts about risk of iron overload in dialysis patients, inhibition of hepcidin, the central key player in iron homeostasis, could be a pivotal strategy in the management of CKD anemia.
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Affiliation(s)
- Alice Santos-Silva
- UCIBIO\REQUIMTE, Laboratory of Biochemistry, Department of Biological Sciences, Faculty of Pharmacy, University of Porto, Porto, Portugal.
| | - Sandra Ribeiro
- UCIBIO\REQUIMTE, Laboratory of Biochemistry, Department of Biological Sciences, Faculty of Pharmacy, University of Porto, Porto, Portugal
| | - Flávio Reis
- Institute of Pharmacology & Experimental Therapeutics, Coimbra Institute for Clinical and Biomedical Research (iCBR), Faculty of Medicine, CNC.IBILI Consortium & CIBB Consortium, University of Coimbra, Coimbra, Portugal
| | - Luís Belo
- UCIBIO\REQUIMTE, Laboratory of Biochemistry, Department of Biological Sciences, Faculty of Pharmacy, University of Porto, Porto, Portugal
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53
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Abstract
Since its discovery in 2001, there have been a number of important discoveries and findings that have increased our knowledge about the functioning of hepcidin. Hepcidin, the master iron regulator has been shown to be regulated by a number of physiological stimuli and their associated signaling pathways. This chapter will summarize our current understanding of how these physiological stimuli and downstream signaling molecules are involved in hepcidin modulation and ultimately contribute to the regulation of systemic or local iron homeostasis. The signaling pathways and molecules described here have been shown to primarily affect hepcidin at a transcriptional level, but these transcriptional changes correlate with changes in systemic iron levels as well, supporting the functional effects of hepcidin regulation by these signaling pathways.
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Affiliation(s)
- Gautam Rishi
- The Liver Disease and Iron Disorders Research Group, Institute of Health and Biomedical Innovation and School of Biomedical Sciences, Queensland University of Technology (QUT), Brisbane, QLD, Australia
| | - V Nathan Subramaniam
- The Liver Disease and Iron Disorders Research Group, Institute of Health and Biomedical Innovation and School of Biomedical Sciences, Queensland University of Technology (QUT), Brisbane, QLD, Australia.
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54
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Rotwein P. Variation in the repulsive guidance molecule family in human populations. Physiol Rep 2019; 7:e13959. [PMID: 30746893 PMCID: PMC6370684 DOI: 10.14814/phy2.13959] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Revised: 11/28/2018] [Accepted: 11/29/2018] [Indexed: 01/17/2023] Open
Abstract
Repulsive guidance molecules, RGMA, RGMB, and RGMC, are related proteins discovered independently through different experimental paradigms. They are encoded by single copy genes in mammalian and other vertebrate genomes, and are ~50% identical in amino acid sequence. The importance of RGM actions in human physiology has not been realized, as most research has focused on non-human models, although mutations in RGMC are the cause of the severe iron storage disorder, juvenile hemochromatosis. Here I show that repositories of human genomic and population genetic data can be used as starting points for discovery and for developing new testable hypotheses about each of these paralogs in human biology and disease susceptibility. Information was extracted, aggregated, and analyzed from the Ensembl and UCSC Genome Browsers, the Exome Aggregation Consortium, the Genotype-Tissue Expression project portal, the cBio portal for Cancer Genomics, and the National Cancer Institute Genomic Data Commons data site. Results identify extensive variation in gene expression patterns, substantial alternative RNA splicing, and possible missense alterations and other modifications in the coding regions of each of the three genes, with many putative mutations being detected in individuals with different types of cancers. Moreover, selected amino acid substitutions are highly prevalent in the world population, with minor allele frequencies of up to 37% for RGMA and up to 8% for RGMB. These results indicate that protein sequence variation is common in the human RGM family, and raises the possibility that individual variants will have a significant population impact on human physiology and/or disease predisposition.
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Affiliation(s)
- Peter Rotwein
- Department of Biomedical SciencesPaul L. Foster School of MedicineTexas Tech Health University Health Sciences CenterEl PasoTexas
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55
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Lakhal-Littleton S. Cardiomyocyte hepcidin: From intracellular iron homeostasis to physiological function. VITAMINS AND HORMONES 2019; 110:189-200. [PMID: 30798812 DOI: 10.1016/bs.vh.2019.01.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Cellular iron is required for the utilization of oxygen in the cell. Iron in iron-sulfur and heme groups is required for electron transfer and oxygen activation in oxidative phosphorylation, while labile free iron is required for oxygen activation by dioxygenases, and as a catalyst for redox signaling. At the same time, this reactivity with oxygen underpins the production of cell-damaging free radicals in the presence of excess iron. Because the cardiac cell is a major site of oxygen flux, it requires tight control of intracellular iron levels. Until recently, such control was thought to be mediated predominantly by the action of iron regulatory proteins. However, new evidence reveals that cardiomyocyte hepcidin is indispensable for the control of intracellular iron levels, normal metabolism and heart function. This new evidence highlights the need for better understanding of the regulation of cardiomyocyte hepcidin in health and disease.
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Affiliation(s)
- S Lakhal-Littleton
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom.
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56
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Wojtunik-Kulesza K, Oniszczuk A, Waksmundzka-Hajnos M. An attempt to elucidate the role of iron and zinc ions in development of Alzheimer's and Parkinson's diseases. Biomed Pharmacother 2019; 111:1277-1289. [PMID: 30841441 DOI: 10.1016/j.biopha.2018.12.140] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2018] [Revised: 12/20/2018] [Accepted: 12/30/2018] [Indexed: 12/31/2022] Open
Abstract
Neurodegenerative disorders are among the most studied issues both in medicine and pharmacy. Despite long and extensive research, there is no effective treatment prescribed for such diseases, including Alzheimer's or Parkinson's. Available data exposes their multi-faceted character that requires a complex and multidirectional approach to treatment. In this case, the most important challenge is to understand the neurodegenerative mechanisms, which should permit the development of more elaborate and effective therapies. In the submitted review, iron and zinc are discussed as important and perfectly possible neurodegenerative factors behind Alzheimer's and Parkinson's diseases. It is commonly known that these elements are present in living organisms and are essential for the proper operation of the body. Still, their influence is positive only when their proper balance is maintained. Otherwise, when any imbalance occurs, this can eventuate in numerous disturbances, among them oxidative stress, accumulation of amyloid β and the formation of neurofibrillary tangles, let alone the increase in α-synuclein concentration. At the same time, available research data reveals certain discrepancies in approaching metal ions as either impassive, helpful, or negative factors influencing the development of neurodegenerative changes. This review outlines selected neurodegenerative disorders, highlights the role of iron and zinc in the human body and discusses cases of their imbalance leading to neurodegenerative changes as shown in vitro and in vivo studies as well as through relevant mechanisms.
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Affiliation(s)
- Karolina Wojtunik-Kulesza
- Department of Inorganic Chemistry, Medical University of Lublin, Chodzki 4a, 20-093, Lublin, Poland.
| | - Anna Oniszczuk
- Department of Inorganic Chemistry, Medical University of Lublin, Chodzki 4a, 20-093, Lublin, Poland.
| | - Monika Waksmundzka-Hajnos
- Department of Inorganic Chemistry, Medical University of Lublin, Chodzki 4a, 20-093, Lublin, Poland.
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Abstract
PURPOSE OF REVIEW We will review non-renal-related mechanisms of fibroblast growth factor 23 (FGF23) pathophysiology. RECENT FINDINGS FGF23 production and metabolism may be affected by many bone, mineral, and kidney factors. However, it has recently been demonstrated that other factors, such as iron status, erythropoietin, and inflammation, also affect FGF23 production and metabolism. As these non-mineral factors are especially relevant in the setting of chronic kidney disease (CKD), they may represent emerging determinants of CKD-associated elevated FGF23 levels. Moreover, FGF23 itself may promote anemia and inflammation, thus contributing to the multifactorial etiologies of these CKD-associated comorbidities. CKD-relevant, non-mineral-related, bidirectional relationships exist between FGF23 and anemia, and between FGF23 and inflammation. Iron deficiency, anemia, and inflammation affect FGF23 production and metabolism, and FGF23 itself may contribute to anemia and inflammation, highlighting complex interactions that may affect aspects of CKD pathogenesis and treatment.
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Affiliation(s)
- Mark R Hanudel
- UCLA Department of Pediatrics, Division of Pediatric Nephrology, David Geffen School of Medicine at UCLA, 10833 Le Conte Avenue, MDCC A2-383, Los Angeles, CA, 90095-1752, USA.
| | - Marciana Laster
- UCLA Department of Pediatrics, Division of Pediatric Nephrology, David Geffen School of Medicine at UCLA, 10833 Le Conte Avenue, MDCC A2-383, Los Angeles, CA, 90095-1752, USA
| | - Isidro B Salusky
- UCLA Department of Pediatrics, Division of Pediatric Nephrology, David Geffen School of Medicine at UCLA, 10833 Le Conte Avenue, MDCC A2-383, Los Angeles, CA, 90095-1752, USA
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58
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Abstract
The liver orchestrates systemic iron balance by producing and secreting hepcidin. Known as the iron hormone, hepcidin induces degradation of the iron exporter ferroportin to control iron entry into the bloodstream from dietary sources, iron recycling macrophages, and body stores. Under physiologic conditions, hepcidin production is reduced by iron deficiency and erythropoietic drive to increase the iron supply when needed to support red blood cell production and other essential functions. Conversely, hepcidin production is induced by iron loading and inflammation to prevent the toxicity of iron excess and limit its availability to pathogens. The inability to appropriately regulate hepcidin production in response to these physiologic cues underlies genetic disorders of iron overload and deficiency, including hereditary hemochromatosis and iron-refractory iron deficiency anemia. Moreover, excess hepcidin suppression in the setting of ineffective erythropoiesis contributes to iron-loading anemias such as β-thalassemia, whereas excess hepcidin induction contributes to iron-restricted erythropoiesis and anemia in chronic inflammatory diseases. These diseases have provided key insights into understanding the mechanisms by which the liver senses plasma and tissue iron levels, the iron demand of erythrocyte precursors, and the presence of potential pathogens and, importantly, how these various signals are integrated to appropriately regulate hepcidin production. This review will focus on recent insights into how the liver senses body iron levels and coordinates this with other signals to regulate hepcidin production and systemic iron homeostasis.
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59
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Masajtis-Zagajewska A, Nowicki M. Effect of atorvastatin on iron metabolism regulation in patients with chronic kidney disease - a randomized double blind crossover study. Ren Fail 2018; 40:700-709. [PMID: 30741616 PMCID: PMC6319462 DOI: 10.1080/0886022x.2018.1535983] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Revised: 08/09/2018] [Accepted: 10/02/2018] [Indexed: 12/16/2022] Open
Abstract
INTRODUCTION To determine the effect of 6-month administration of atorvastatin on hepcidin and hemojuvelin levels, inflammatory parameters and iron metabolism in patients with chronic kidney disease (CKD) stages 3 and 4. METHODS Thirty six statin- and erythropoiesis-stimulating agent-naive patients with CKD stages 3 and 4 and LDL cholesterol ≥100 mg/dl received atorvastatin or placebo for two 6-month periods in a double blind, randomized crossover study. Hepcidin, hemojuvelin, hsCRP, IL-6, hemoglobin, red blood cell distribution width, iron, total iron binding capacity (TIBC), and unsaturated iron binding capacity (UIBC) were measured before and after each treatment period. RESULTS Hepcidin decreased (from 102 [307] to 63 [170] pg/ml (p > .001)) in the course of statin therapy but remained unchanged after placebo administration (173 [256] to 153 [204] pg/ml, respectively). Hemojuvelin did not change after either part of the study. Both IL-6 and hsCRP decreased following statin therapy (from 8.7 [12.0] to 8.1 [13.9] pg/ml; p = .04 and from 4.7 [4.0] to 4.0 [3.6] mg/l; p = .4, respectively), but did not change after placebo administration. Blood hemoglobin increased slightly but significantly after 6-month statin therapy (from 11.6 ± 1.6 to 11.9 ± 1.5 g/dl, p = .002), and was unchanged after placebo treatment. TIBC and UIBC increased significantly after 6-month statin therapy, and serum iron also tended to increase. The change of eGFR during the study did not differ between the two treatment periods. CONCLUSIONS Statin may have a small but potentially beneficial effect on serum hepcidin, which may lead to improvement of anemia control in CKD patients.
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Affiliation(s)
- Anna Masajtis-Zagajewska
- Department of Nephrology, Hypertension and Kidney Transplantation, Medical University of Lodz, University Hospital and Teaching Center, Lodz, Poland
| | - Michal Nowicki
- Department of Nephrology, Hypertension and Kidney Transplantation, Medical University of Lodz, University Hospital and Teaching Center, Lodz, Poland
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60
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Ueda N, Takasawa K. Impact of Inflammation on Ferritin, Hepcidin and the Management of Iron Deficiency Anemia in Chronic Kidney Disease. Nutrients 2018; 10:nu10091173. [PMID: 30150549 PMCID: PMC6163440 DOI: 10.3390/nu10091173] [Citation(s) in RCA: 95] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Revised: 08/08/2018] [Accepted: 08/17/2018] [Indexed: 12/16/2022] Open
Abstract
Iron deficiency anemia (IDA) is a major problem in chronic kidney disease (CKD), causing increased mortality. Ferritin stores iron, representing iron status. Hepcidin binds to ferroportin, thereby inhibiting iron absorption/efflux. Inflammation in CKD increases ferritin and hepcidin independent of iron status, which reduce iron availability. While intravenous iron therapy (IIT) is superior to oral iron therapy (OIT) in CKD patients with inflammation, OIT is as effective as IIT in those without. Inflammation reduces predictive values of ferritin and hepcidin for iron status and responsiveness to iron therapy. Upper limit of ferritin to predict iron overload is higher in CKD patients with inflammation than in those without. However, magnetic resonance imaging studies show lower cutoff levels of serum ferritin to predict iron overload in dialysis patients with apparent inflammation than upper limit of ferritin proposed by international guidelines. Compared to CKD patients with inflammation, optimal ferritin levels for IDA are lower in those without, requiring reduced iron dose and leading to decreased mortality. The management of IDA should differ between CKD patients with and without inflammation and include minimization of inflammation. Further studies are needed to determine the impact of inflammation on ferritin, hepcidin and therapeutic strategy for IDA in CKD.
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Affiliation(s)
- Norishi Ueda
- Department of Pediatrics, Public Central Hospital of Matto Ishikawa, 3-8 Kuramitsu, Hakusan, Ishikawa 924-8588, Japan.
| | - Kazuya Takasawa
- Department of Internal Medicine, Public Central Hospital of Matto Ishikawa, 3-8 Kuramitsu, Hakusan, Ishikawa 924-8588, Japan.
- Department of Internal Medicine, Public Tsurugi Hospital, Ishikawa 920-2134, Japan.
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61
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van Duijn S, Bulk M, van Duinen SG, Nabuurs RJA, van Buchem MA, van der Weerd L, Natté R. Cortical Iron Reflects Severity of Alzheimer's Disease. J Alzheimers Dis 2018; 60:1533-1545. [PMID: 29081415 PMCID: PMC5676973 DOI: 10.3233/jad-161143] [Citation(s) in RCA: 104] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Abnormal iron distribution in the isocortex is increasingly recognized as an in vivo marker for Alzheimer’s disease (AD). However, the contribution of iron accumulation to the AD pathology is still poorly understood. In this study, we investigated: 1) frontal cortical iron distribution in AD and normal aging and 2) the relation between iron distribution and degree of AD pathology. We used formalin fixed paraffin embedded frontal cortex from 10 AD patients, 10 elder, 10 middle aged, and 10 young controls and visualized iron with a modified Perl’s histochemical procedure. AD and elderly subjects were not different with respect to age and sex distribution. Iron distribution in the frontal cortex was not affected by normal aging but was clearly different between AD and controls. AD showed accumulation of iron in plaques, activated microglia, and, in the most severe cases, in the mid-cortical layers along myelinated fibers. The degree of altered iron accumulations was correlated to the amount of amyloid-β plaques and tau pathology in the same block, as well as to Braak stage (p < 0.001). AD and normal aging show different iron and myelin distribution in frontal cortex. These changes appear to occur after the development of the AD pathological hallmarks. These findings may help the interpretation of high resolution in vivo MRI and suggest the potential of using changes in iron-based MRI contrast to indirectly determine the degree of AD pathology in the frontal cortex.
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Affiliation(s)
- Sara van Duijn
- Department of Pathology, Leiden University Medical Centre, Leiden, The Netherlands
| | - Marjolein Bulk
- Department of Radiology, Leiden University Medical Centre, Leiden, The Netherlands.,Department of Human Genetics, Leiden University Medical Centre, Leiden, The Netherlands.,Percuros BV, Leiden, The Netherlands
| | - Sjoerd G van Duinen
- Department of Pathology, Leiden University Medical Centre, Leiden, The Netherlands
| | - Rob J A Nabuurs
- Department of Radiology, Leiden University Medical Centre, Leiden, The Netherlands
| | - Mark A van Buchem
- Department of Radiology, Leiden University Medical Centre, Leiden, The Netherlands
| | - Louise van der Weerd
- Department of Radiology, Leiden University Medical Centre, Leiden, The Netherlands.,Department of Human Genetics, Leiden University Medical Centre, Leiden, The Netherlands
| | - Remco Natté
- Department of Pathology, Leiden University Medical Centre, Leiden, The Netherlands
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62
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Ravasi G, Pelucchi S, Buoli Comani G, Greni F, Mariani R, Pelloni I, Bombelli S, Perego R, Barisani D, Piperno A. Hepcidin regulation in a mouse model of acute hypoxia. Eur J Haematol 2018. [PMID: 29543343 DOI: 10.1111/ejh.13062] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
OBJECTIVE During hypoxia, hepcidin expression is inhibited to allow iron mobilization to sustain erythropoietic expansion. We analyzed molecular mechanisms underlying hypoxia-induced hepcidin inhibition in an in vivo model of acute hypoxia. METHODS Mice were kept under normal or hypoxic conditions for 6 hours and 15 hours and treated with α-PDGF-BB antibody or PDGF-BB receptor inhibitor. Blood, liver, spleen, and bone marrow were collected to extract RNA and protein or to quantify EPO and PDGF-BB. mRNA and protein levels were assessed by RT-PCR and Western blot. RESULTS Hepcidin was strongly inhibited at 15 hours, and this downregulation followed erythropoiesis activation and upregulation of several growth factors. PDGF-BB, erythroferrone, GDF15, and TWSG1 were upregulated by hypoxia in the bone marrow, but not in spleen or liver. Inactivation of PDGF-BB or its receptor suppressed the hypoxia-induced hepcidin inhibition. CONCLUSION Spleen and liver are not involved in the early stages of hypoxia-induced hepcidin downregulation. Our data support the role of PDGF-BB and probably also of erythroferrone in the recruitment of iron for erythropoiesis in the hypoxia setting. The rapid normalization of all the erythroid factors against persistent hepcidin suppression suggests that other signals are involved that should be clarified in future studies.
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Affiliation(s)
- Giulia Ravasi
- School of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy
| | - Sara Pelucchi
- School of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy
| | - Gaia Buoli Comani
- School of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy
| | - Federico Greni
- School of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy
| | - Raffaella Mariani
- Centre for Disorder of Iron Metabolism, ASST-Monza - S.Gerardo Hospital, Monza, Italy
| | - Irene Pelloni
- Centre for Disorder of Iron Metabolism, ASST-Monza - S.Gerardo Hospital, Monza, Italy
| | - Silvia Bombelli
- School of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy
| | - Roberto Perego
- School of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy
| | - Donatella Barisani
- School of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy
| | - Alberto Piperno
- School of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy.,Centre for Disorder of Iron Metabolism, ASST-Monza - S.Gerardo Hospital, Monza, Italy
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63
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Silva I, Rausch V, Peccerella T, Millonig G, Seitz HK, Mueller S. Hypoxia enhances H 2O 2-mediated upregulation of hepcidin: Evidence for NOX4-mediated iron regulation. Redox Biol 2018; 16:1-10. [PMID: 29459227 PMCID: PMC5832675 DOI: 10.1016/j.redox.2018.02.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2018] [Revised: 02/03/2018] [Accepted: 02/10/2018] [Indexed: 12/21/2022] Open
Abstract
The exact regulation of the liver-secreted peptide hepcidin, the key regulator of systemic iron homeostasis, is still poorly understood. It is potently induced by iron, inflammation, cytokines or H2O2 but conflicting results have been reported on hypoxia. In our current study, we first show that pronounced (1%) and mild (5%) hypoxia strongly induces hepcidin in human Huh7 hepatoma and primary liver cells predominantly at the transcriptional level via STAT3 using two hypoxia systems (hypoxia chamber and enzymatic hypoxia by the GOX/CAT system). SiRNA silencing of JAK1, STAT3 and NOX4 diminished the hypoxia-mediated effect while a role of HIF1α could be clearly ruled out by the response to hypoxia-mimetics and competition experiments with a plasmid harboring the oxygen-dependent degradation domain of HIF1α. Specifically, hypoxia drastically enhances the H2O2-mediated induction of hepcidin strongly pointing towards an oxidase as powerful upstream control of hepcidin. We finally provide evidences for an efficient regulation of hepcidin expression by NADPH-dependent oxidase 4 (NOX4) in liver cells. In summary, our data demonstrate that hypoxia strongly potentiates the peroxide-mediated induction of hepcidin via STAT3 signaling pathway. Moreover, oxidases such as NOX4 or artificially overexpressed urate oxidase (UOX) can induce hepcidin. It remains to be studied whether the peroxide-STAT3-hepcidin axis simply acts to continuously compensate for oxygen fluctuations or is directly involved in iron sensing per se. Hypoxia strongly induces hepcidin via STAT3 signaling. HIF1α is not involved in hepcidin regulation under hypoxia. Hypoxia enhances hydrogen peroxide-mediated hepcidin induction. Oxidases, such as NOX4 are powerful inducers of hepcidin.
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Affiliation(s)
- Inês Silva
- Center for Alcohol Research, University of Heidelberg and Salem Medical Center, Heidelberg, Germany
| | - Vanessa Rausch
- Center for Alcohol Research, University of Heidelberg and Salem Medical Center, Heidelberg, Germany
| | - Teresa Peccerella
- Center for Alcohol Research, University of Heidelberg and Salem Medical Center, Heidelberg, Germany
| | - Gunda Millonig
- Center for Alcohol Research, University of Heidelberg and Salem Medical Center, Heidelberg, Germany
| | - Helmut-Karl Seitz
- Center for Alcohol Research, University of Heidelberg and Salem Medical Center, Heidelberg, Germany
| | - Sebastian Mueller
- Center for Alcohol Research, University of Heidelberg and Salem Medical Center, Heidelberg, Germany.
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64
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Hemojuvelin Predicts Acute Kidney Injury and Poor Outcomes Following Cardiac Surgery. Sci Rep 2018; 8:1938. [PMID: 29386545 PMCID: PMC5792584 DOI: 10.1038/s41598-018-20212-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2016] [Accepted: 01/15/2018] [Indexed: 01/27/2023] Open
Abstract
Acute kidney injury (AKI) is detrimental after cardiac surgery. In this multicenter study, the novel biomarker hemojuvelin (HJV) was evaluated for AKI prediction following cardiac surgery. Urinary HJV, neutrophil gelatinase-associated lipocalin (NGAL), and urinary creatinine were measured in 151 patients after surgery. The outcomes of advanced AKI (KDIGO stages 2 and 3) and all causes of in-hospital mortality as the composite outcome were recorded. Areas under the receiver operator characteristic curves (AUC) and a multivariate generalized additive model (GAM) were applied to predict these outcomes of interest. Urinary HJV differentiated patients with/without AKI, advanced AKI or composite outcome after surgery (p < 0.001, by a generalized estimating equation) in this study. At three hours post-surgery, urinary HJV predicted advanced AKI (p < 0.001) and composite outcome (p < 0.001) with corresponding AUC values of 0.768 and 0.828, respectively. The performance of creatinine-adjusted HJV was also superior to NGAL in predicting advanced AKI (AUC = 0.784 and 0.694; p = 0.037) and composite outcome (AUC = 0.842 and 0.676; p = 0.002). The integration of HJV into the Cleveland Clinic score for advanced AKI led to a significant increase in risk stratification (net reclassification improvement [NRI] = 0.598; p < 0.001).
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65
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Kaplan JM, Sharma N, Dikdan S. Hypoxia-Inducible Factor and Its Role in the Management of Anemia in Chronic Kidney Disease. Int J Mol Sci 2018; 19:ijms19020389. [PMID: 29382128 PMCID: PMC5855611 DOI: 10.3390/ijms19020389] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2017] [Revised: 01/04/2018] [Accepted: 01/08/2018] [Indexed: 12/25/2022] Open
Abstract
Hypoxia-inducible factor (HIF) plays a crucial role in the response to hypoxia at the cellular, tissue, and organism level. New agents under development to pharmacologically manipulate HIF may provide new and exciting possibilities in the treatment of anemia of chronic kidney disease (CKD) as well as in multiple other disease states involving ischemia-reperfusion injury. This article provides an overview of recent studies describing current standards of care for patients with anemia in CKD and associated clinical issues, and those supporting the clinical potential for targeting HIF stabilization with HIF prolyl-hydroxylase inhibitors (HIF-PHI) in these patients. Additionally, articles reporting the clinical potential for HIF-PHIs in 'other' putative therapeutic areas, the tissue and intracellular distribution of HIF- and prolyl-hydroxylase domain (PHD) isoforms, and HIF isoforms targeted by the different PHDs, were identified. There is increasing uncertainty regarding the optimal treatment for anemia of CKD with poorer outcomes associated with treatment to higher hemoglobin targets, and the increasing use of iron and consequent risk of iron imbalance. Attainment and maintenance of more physiologic erythropoietin levels associated with HIF stabilization may improve the management of patients resistant to treatment with erythropoiesis-stimulating agents and improve outcomes at higher hemoglobin targets.
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Affiliation(s)
- Joshua M Kaplan
- Division of Nephrology and Hypertension, Rutgers-New Jersey Medical School, University Hospital, 185 South Orange Avenue, I512, Newark, NJ 07103, USA.
| | - Neeraj Sharma
- Division of Nephrology and Hypertension, Rutgers-New Jersey Medical School, University Hospital, 185 South Orange Avenue, I512, Newark, NJ 07103, USA.
| | - Sean Dikdan
- Division of Nephrology and Hypertension, Rutgers-New Jersey Medical School, University Hospital, 185 South Orange Avenue, I512, Newark, NJ 07103, USA.
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66
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Nickel J, Ten Dijke P, Mueller TD. TGF-β family co-receptor function and signaling. Acta Biochim Biophys Sin (Shanghai) 2018; 50:12-36. [PMID: 29293886 DOI: 10.1093/abbs/gmx126] [Citation(s) in RCA: 123] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Accepted: 11/08/2017] [Indexed: 01/04/2023] Open
Abstract
Transforming growth factor-β (TGF-β) family members, which include TGF-βs, activins and bone morphogenetic proteins, are pleiotropic cytokines that elicit cell type-specific effects in a highly context-dependent manner in many different tissues. These secreted protein ligands signal via single-transmembrane Type I and Type II serine/threonine kinase receptors and intracellular SMAD transcription factors. Deregulation in signaling has been implicated in a broad array of diseases, and implicate the need for intricate fine tuning in cellular signaling responses. One important emerging mechanism by which TGF-β family receptor signaling intensity, duration, specificity and diversity are regulated and/or mediated is through cell surface co-receptors. Here, we provide an overview of the co-receptors that have been identified for TGF-β family members. While some appear to be specific to TGF-β family members, others are shared with other pathways and provide possible ways for signal integration. This review focuses on novel functions of TGF-β family co-receptors, which continue to be discovered.
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Affiliation(s)
- Joachim Nickel
- Universitätsklinikum Würzburg, Lehrstuhl für Tissue Engineering und Regenerative Medizin und Fraunhofer Institut für Silicatforschung (ISC), Translationszentrum "Regenerative Therapien", Röntgenring 11, D-97070 Würzburg, Germany
| | - Peter Ten Dijke
- Department of Molecular and Cell Biology and Cancer Genomics Centre Netherlands, Leiden University Medical Center, Einthovenweg 20, 2300 RC Leiden, The Netherlands
| | - Thomas D Mueller
- Lehrstuhl für molekulare Pflanzenphysiologie und Biophysik, Julius-von-Sachs Institut für Biowissenschaften, Universität Würzburg, Julius-von-Sachs-Platz 2, D-97082 Würzburg, Germany
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67
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The relationship between systemic iron homeostasis and erythropoiesis. Biosci Rep 2017; 37:BSR20170195. [PMID: 29097483 PMCID: PMC5705776 DOI: 10.1042/bsr20170195] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Revised: 10/27/2017] [Accepted: 10/30/2017] [Indexed: 12/20/2022] Open
Abstract
Red blood cell production (erythropoiesis) is the single largest consumer of iron in the body; this need is satisfied by maintaining a sensitive regulation of iron levels. The level of erythropoietic demand regulates the expression of the iron hormone hepcidin and thus iron absorption. Erythropoiesis-mediated regulation of hepcidin is an area of increasing importance and recent studies have identified a number of potential regulatory proteins. This review summarizes our current knowledge about these candidate erythroid regulators of hepcidin and the relation between transferrin receptors and erythropoiesis.
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Bulk M, Abdelmoula WM, Nabuurs RJA, van der Graaf LM, Mulders CWH, Mulder AA, Jost CR, Koster AJ, van Buchem MA, Natté R, Dijkstra J, van der Weerd L. Postmortem MRI and histology demonstrate differential iron accumulation and cortical myelin organization in early- and late-onset Alzheimer's disease. Neurobiol Aging 2017; 62:231-242. [PMID: 29195086 DOI: 10.1016/j.neurobiolaging.2017.10.017] [Citation(s) in RCA: 79] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Revised: 10/18/2017] [Accepted: 10/18/2017] [Indexed: 11/15/2022]
Abstract
Previous MRI studies reported cortical iron accumulation in early-onset (EOAD) compared to late-onset (LOAD) Alzheimer disease patients. However, the pattern and origin of iron accumulation is poorly understood. This study investigated the histopathological correlates of MRI contrast in both EOAD and LOAD. T2*-weighted MRI was performed on postmortem frontal cortex of controls, EOAD, and LOAD. Images were ordinally scored using predefined criteria followed by histology. Nonlinear histology-MRI registration was used to calculate pixel-wise spatial correlations based on the signal intensity. EOAD and LOAD were distinguishable based on 7T MRI from controls and from each other. Histology-MRI correlation analysis of the pixel intensities showed that the MRI contrast is best explained by increased iron accumulation and changes in cortical myelin, whereas amyloid and tau showed less spatial correspondence with T2*-weighted MRI. Neuropathologically, subtypes of Alzheimer's disease showed different patterns of iron accumulation and cortical myelin changes independent of amyloid and tau that may be detected by high-field susceptibility-based MRI.
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Affiliation(s)
- Marjolein Bulk
- Department of Radiology, Leiden University Medical Center, Leiden, the Netherlands; Department of Human Genetics, Leiden University Medical Center, Leiden, the Netherlands; Percuros BV, Leiden, the Netherlands.
| | - Walid M Abdelmoula
- Department of Radiology, Leiden University Medical Center, Leiden, the Netherlands
| | - Rob J A Nabuurs
- Department of Radiology, Leiden University Medical Center, Leiden, the Netherlands
| | - Linda M van der Graaf
- Department of Radiology, Leiden University Medical Center, Leiden, the Netherlands; Department of Human Genetics, Leiden University Medical Center, Leiden, the Netherlands
| | - Coen W H Mulders
- Department of Radiology, Leiden University Medical Center, Leiden, the Netherlands
| | - Aat A Mulder
- Department of Molecular Cell Biology, Electron Microscopy Section, Leiden University Medical Center, Leiden, the Netherlands
| | - Carolina R Jost
- Department of Molecular Cell Biology, Electron Microscopy Section, Leiden University Medical Center, Leiden, the Netherlands
| | - Abraham J Koster
- Department of Molecular Cell Biology, Electron Microscopy Section, Leiden University Medical Center, Leiden, the Netherlands
| | - Mark A van Buchem
- Department of Radiology, Leiden University Medical Center, Leiden, the Netherlands
| | - Remco Natté
- Department of Pathology, Leiden University Medical Center, Leiden, the Netherlands
| | - Jouke Dijkstra
- Department of Radiology, Leiden University Medical Center, Leiden, the Netherlands
| | - Louise van der Weerd
- Department of Radiology, Leiden University Medical Center, Leiden, the Netherlands; Department of Human Genetics, Leiden University Medical Center, Leiden, the Netherlands
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69
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Does Hypoxia Cause Carcinogenic Iron Accumulation in Alcoholic Liver Disease (ALD)? Cancers (Basel) 2017; 9:cancers9110145. [PMID: 29068390 PMCID: PMC5704163 DOI: 10.3390/cancers9110145] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2017] [Revised: 10/19/2017] [Accepted: 10/20/2017] [Indexed: 02/06/2023] Open
Abstract
Alcoholic liver disease (ALD) is a leading health risk worldwide. Hepatic iron overload is frequently observed in ALD patients and it is an important and independent factor for disease progression, survival, and the development of primary liver cancer (HCC). At a systemic level, iron homeostasis is controlled by the liver-secreted hormone hepcidin. Hepcidin regulation is complex and still not completely understood. It is modulated by many pathophysiological conditions associated with ALD, such as inflammation, anemia, oxidative stress/H2O2, or hypoxia. Namely, the data on hypoxia-signaling of hepcidin are conflicting, which seems to be mainly due to interpretational limitations of in vivo data and methodological challenges. Hence, it is often overlooked that hepcidin-secreting hepatocytes are physiologically exposed to 2–7% oxygen, and that key oxygen species such as H2O2 act as signaling messengers in such a hypoxic environment. Indeed, with the recently introduced glucose oxidase/catalase (GOX/CAT) system it has been possible to independently study hypoxia and H2O2 signaling. First preliminary data indicate that hypoxia enhances H2O2-mediated induction of hepcidin, pointing towards oxidases such as NADPH oxidase 4 (NOX4). We here review and discuss novel concepts of hypoxia signaling that could help to better understand hepcidin-associated iron overload in ALD.
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70
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Vähätupa M, Cordova ZM, Barker H, Aittomäki S, Uusitalo H, Järvinen TAH, Pesu M, Uusitalo-Järvinen H. Furin deficiency in myeloid cells leads to attenuated revascularization in a mouse-model of oxygen-induced retinopathy. Exp Eye Res 2017; 166:160-167. [PMID: 29031855 DOI: 10.1016/j.exer.2017.10.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Revised: 09/01/2017] [Accepted: 10/11/2017] [Indexed: 12/12/2022]
Abstract
Ischemic retinopathy is a vision-threatening disease associated with chronic retinal inflammation and hypoxia leading to abnormal angiogenesis. Furin, a member of the proprotein convertase family of proteins, has been implicated in the regulation of angiogenesis due to its essential role in the activation of several angiogenic growth factors, including vascular endothelial growth factor-C (VEGF-C), VEGF-D and transforming growth factor - β (TGF- β). In the present study, we evaluated expression of furin in the retina and its role in retinal angiogenesis. As both inflammation and hypoxia contribute to angiogenesis, the role of furin was evaluated using myeloid-cell specific furin knockout (KO) mice (designated LysMCre-fur(fl/fl)) both in developmental retinal angiogenesis as well as in hypoxia-driven angiogenesis using the oxygen-induced retinopathy (OIR) model. In the retina, furin expression was detected in endothelial cells, macrophages and, to some extent, in neurons. The rate of angiogenesis was not different in LysMCre-fur(fl/fl) mice when compared to their wild-type littermates during development. In the OIR model, the revascularization of retina was significantly delayed in LysMCre-fur(fl/fl) mice compared to their wild-type littermates, while there was no compensatory increase in the preretinal neovascularization in LysMCre-fur(fl/fl) mice. These results demonstrate that furin expression in myeloid cells plays a significant role in hypoxia-induced angiogenesis in retina.
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Affiliation(s)
- Maria Vähätupa
- Faculty of Medicine & Life Sciences, University of Tampere, Tampere, Finland
| | - Zuzet Martinez Cordova
- Faculty of Medicine & Life Sciences, University of Tampere, Tampere, Finland; Immunoregulation, Institute of Biosciences and Medical Technology (BioMediTech), University of Tampere, Tampere, Finland
| | - Harlan Barker
- Faculty of Medicine & Life Sciences, University of Tampere, Tampere, Finland
| | - Saara Aittomäki
- Faculty of Medicine & Life Sciences, University of Tampere, Tampere, Finland; Immunoregulation, Institute of Biosciences and Medical Technology (BioMediTech), University of Tampere, Tampere, Finland
| | - Hannu Uusitalo
- Faculty of Medicine & Life Sciences, University of Tampere, Tampere, Finland; Eye Centre, Tampere University Hospital, Tampere, Finland
| | - Tero A H Järvinen
- Faculty of Medicine & Life Sciences, University of Tampere, Tampere, Finland; Departments of Musculoskeletal Disorders, Tampere University Hospital, Tampere, Finland
| | - Marko Pesu
- Faculty of Medicine & Life Sciences, University of Tampere, Tampere, Finland; Immunoregulation, Institute of Biosciences and Medical Technology (BioMediTech), University of Tampere, Tampere, Finland; Departments of Dermatology, Tampere University Hospital, Tampere, Finland
| | - Hannele Uusitalo-Järvinen
- Faculty of Medicine & Life Sciences, University of Tampere, Tampere, Finland; Eye Centre, Tampere University Hospital, Tampere, Finland.
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71
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Lakhal-Littleton S, Robbins PA. The interplay between iron and oxygen homeostasis with a particular focus on the heart. J Appl Physiol (1985) 2017; 123:967-973. [PMID: 28775066 DOI: 10.1152/japplphysiol.00237.2017] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Revised: 07/10/2017] [Accepted: 07/29/2017] [Indexed: 12/11/2022] Open
Abstract
Iron is subject to tight homeostatic control in mammals. At the systemic level, iron homeostasis is controlled by the liver-derived hormone hepcidin acting on its target ferroportin in the gut, spleen, and liver, which form the sites of iron uptake, recycling, and storage, respectively. At the cellular level, iron homeostasis is dependent on the iron regulatory proteins IRP1/IRP2. Unique chemical properties of iron underpin its importance in biochemical reactions involving oxygen. As such, it is not surprising that there are reciprocal regulatory links between iron and oxygen homeostasis, operating both at the systemic and cellular levels. Hypoxia activates the IRP pathway, and in addition suppresses liver hepcidin through endocrine factors that have yet to be fully elucidated. This review summarizes current knowledge on the interplay between oxygen and iron homeostasis and describes recent insights gained into this interaction in the context of the heart. These include the recognition that the hepcidin/ferroportin axis plays a vital role in the regulation of intracellular iron homeostasis as well as regulating systemic iron availability. As is the case for other aspects of iron homeostasis, hypoxia significantly modulates the function of the hepcidin/ferroportin pathway in the heart. Key areas still to understand are the interactions between cardiac iron and diseases of the heart where hypoxia is a recognized component.
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Affiliation(s)
- Samira Lakhal-Littleton
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Peter Alistair Robbins
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
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72
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Characterization of plasma metal profiles in Alzheimer's disease using multivariate statistical analysis. PLoS One 2017; 12:e0178271. [PMID: 28719622 PMCID: PMC5515399 DOI: 10.1371/journal.pone.0178271] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Accepted: 05/10/2017] [Indexed: 12/04/2022] Open
Abstract
The exact cause of Alzheimer’s disease (AD) and the role of metals in its etiology remain unclear. We have used an analytical approach, based on inductively coupled plasma mass spectrometry coupled with multivariate statistical analysis, to study the profiles of a wide range of metals in AD patients and healthy controls. AD cannot be cured and the lack of sensitive biomarkers that can be used in the early stages of the disease may contribute to this treatment failure. In the present study, we measured plasma levels of amyloid-β1–42(0.142±0.029μg/L)and furin(2.292±1.54μg/L), together with those of the metalloproteinases, insulin-degrading enzyme(1.459±1.14μg/L) and neprilysin(0.073±0.015μg/L), in order to develop biomarkers for AD. Partial least squares discriminant analysis models were used to refine intergroup differences and we discovered that four metals(Mn, Al, Li, Cu) in peripheral blood were strongly associated with AD. Aberration in homeostasis of these metals may alter levels of proteinases, such as furin, which are associated with neurodegeneration in AD and can be a used as plasma-based biomarkers.
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73
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Jaaks P, Bernasconi M. The proprotein convertase furin in tumour progression. Int J Cancer 2017; 141:654-663. [PMID: 28369813 DOI: 10.1002/ijc.30714] [Citation(s) in RCA: 94] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Revised: 03/06/2017] [Accepted: 03/23/2017] [Indexed: 01/17/2023]
Abstract
Proprotein convertases are proteases that have been implicated in the activation of a wide variety of proteins. These proteins are generally synthesised as precursor proteins and require limited proteolysis for conversion into their mature bioactive counterparts. Many of these proteins, including metalloproteases, growth factors and their receptors or adhesion molecules, have been shown to facilitate tumour formation and progression. Hence, this review will focus on the proprotein convertase furin and its role in cancer. The expression of furin has been confirmed in a large spectrum of cancers such as head and neck squamous cell carcinoma, breast cancer and rhabdomyosarcoma. Functional studies modulating furin activity uncovered its importance for the processing of many cancer-related substrates and strongly indicate that high furin activity promotes the malignant phenotype of cancer cells. In this review, we summarise the expression and function of furin in different cancer types, discuss its role in processing cancer-related proproteins and give examples of potential therapeutic approaches that take advantage of the proteolytic activity of furin in cancer cells.
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Affiliation(s)
- Patricia Jaaks
- Department of Oncology, University Children's Hospital Zurich, Zurich, Switzerland.,Children's Research Centre, University Children's Hospital Zurich, Zurich, Switzerland
| | - Michele Bernasconi
- Department of Oncology, University Children's Hospital Zurich, Zurich, Switzerland.,Children's Research Centre, University Children's Hospital Zurich, Zurich, Switzerland
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74
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Abstract
There are numerous blood-based biomarkers for assessing iron stores, but all come with certain limitations. Hepcidin is a hormone primarily produced in the liver that has been proposed as the 'master regulator' of dietary uptake and iron metabolism, and has enormous potential to provide a 'real time' indicator of body iron levels. In this Minireview, the biochemical function of hepcidin in regulating iron levels will be discussed, with a specific focus on how hepcidin can aid in the assessment of iron stores and clinical diagnosis of iron deficiency, iron deficiency anaemia and other iron-related disorders. The role hepcidin itself plays in diseases of iron metabolism will be examined, and current efforts to translate hepcidin assays into the clinic will be critically appraised. Potential limitations of hepcidin as a marker of iron need will also be addressed, as well as the development of new therapies that directly target the hormone that sits atop the hierarchy of systemic iron metabolism.
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Affiliation(s)
- Dominic J Hare
- The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, 30 Royal Parade, Parkville, Victoria 3052, Australia.
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75
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Siebold C, Yamashita T, Monnier PP, Mueller BK, Pasterkamp RJ. RGMs: Structural Insights, Molecular Regulation, and Downstream Signaling. Trends Cell Biol 2017; 27:365-378. [PMID: 28007423 PMCID: PMC5404723 DOI: 10.1016/j.tcb.2016.11.009] [Citation(s) in RCA: 76] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2016] [Revised: 11/27/2016] [Accepted: 11/28/2016] [Indexed: 12/20/2022]
Abstract
Although originally discovered as neuronal growth cone-collapsing factors, repulsive guidance molecules (RGMs) are now known as key players in many fundamental processes, such as cell migration, differentiation, iron homeostasis, and apoptosis, during the development and homeostasis of many tissues and organs, including the nervous, skeletal, and immune systems. Furthermore, three RGMs (RGMa, RGMb/DRAGON, and RGMc/hemojuvelin) have been linked to the pathogenesis of various disorders ranging from multiple sclerosis (MS) to cancer and juvenile hemochromatosis (JHH). While the molecular details of these (patho)biological effects and signaling modes have long remained unknown, recent studies unveil several exciting and novel aspects of RGM processing, ligand-receptor interactions, and downstream signaling. In this review, we highlight recent advances in the mechanisms-of-action and function of RGM proteins.
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Affiliation(s)
- Christian Siebold
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
| | - Toshihide Yamashita
- Department of Molecular Neuroscience, Graduate School of Medicine, Osaka University, 2-2, Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Philippe P Monnier
- Krembil Research Institute, 60 Leonard Street, M5T 2S8, Toronto, ONT, Canada
| | - Bernhard K Mueller
- Neuroscience Discovery Research, Abbvie, Knollstrasse 50, 67061 Ludwigshafen, Germany
| | - R Jeroen Pasterkamp
- Department of Translational Neuroscience, Brain Center Rudolf Magnus, University Medical Center, Universiteitsweg 100, 3584 CG, Utrecht, The Netherlands.
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76
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Li L, Zhang JG, Zhao MZ, Wu ZH, Song JX. Applied value of monitoring serum hepcidin in differential diagnosis of infection versus tumor fevers. ACTA ACUST UNITED AC 2017; 37:253-256. [PMID: 28397053 DOI: 10.1007/s11596-017-1724-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2016] [Revised: 01/11/2017] [Indexed: 12/23/2022]
Abstract
The applied value of serum hepcidin in differential diagnosis of infection fevers versus tumor fevers was explored. A total of 432 fever patients were selected according to the domestic fever of unknown origin (FUO) diagnostic criteria from our hospital between June 2010 and November 2013. Venous blood samples were taken on the day 1, 5, 10 after admission. The infection group (98 cases) and the tumor group (50 cases) were set up based on the clinical and laboratory findings. ELISA was used to determine the serum hepcidin and IL-6 levels. SPSS 13.0 was used for statistical analysis. Hepcidin showed obvious descending trend on the 10th day in both the bacterial infection group (66 cases) and the virus infection group (32 cases), and the descending trend was similar to that of inflammatory indexes such as procalcitonin (PCT), hypersensitive C-reactive protein (h-CRP), erythrocyte sedimentation rate (ESR), white blood cell (WBC), and ferritin. Serum hepcidin showed no obvious differences in the tumor group on the day 1, 5, 10 after admission. In the infection groups, serum hepcidin was positively correlated with IL-6 (r=0.687, P=0.000) and CRP (r=0.487, P=0.026), but had a poor correlation with blood sedimentation, ferritin, PCT and WBC (P>0.05). Monitoring dynamic changes of hepcidin and related inflammatory factors in patients with fever is expected to be used for clinical identification of infection fever and tumor fever.
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Affiliation(s)
- Ling Li
- Department of Infectious Diseases, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China.,Department of Endocrinology, Xiaogan Hospital, Wuhan University of Science and Technology, Xiaogan, 432100, China
| | - Jiang-Guo Zhang
- Department of Infectious Diseases, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Man-Zhi Zhao
- Department of Infectious Diseases, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Zhu-Hua Wu
- Department of Infectious Diseases, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Jian-Xin Song
- Department of Infectious Diseases, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China.
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Langer AL, Ginzburg YZ. Role of hepcidin-ferroportin axis in the pathophysiology, diagnosis, and treatment of anemia of chronic inflammation. Hemodial Int 2017; 21 Suppl 1:S37-S46. [PMID: 28328181 DOI: 10.1111/hdi.12543] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Anemia of chronic inflammation (ACI) is a frequently diagnosed anemia and portends an independently increased morbidity and poor outcome associated with multiple underlying diseases. The pathophysiology of ACI is multifactorial, resulting from the effects of inflammatory cytokines which both directly and indirectly suppress erythropoiesis. Recent advances in molecular understanding of iron metabolism provide strong evidence that immune mediators, such as IL-6, lead to hepcidin-induced hypoferremia, iron sequestration, and decreased iron availability for erythropoiesis. The role of hepcidin-ferroportin axis in the pathophysiology of ACI is stimulating the development of new diagnostics and targeted therapies. In this review, we present an overview of and rationale for inflammation-, iron-, and erythropoiesis-related strategies currently in development.
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Affiliation(s)
- Arielle L Langer
- Division of Hematology and Oncology, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Yelena Z Ginzburg
- Division of Hematology and Oncology, Icahn School of Medicine at Mount Sinai, New York, New York, USA
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78
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79
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Hanudel MR, Chua K, Rappaport M, Gabayan V, Valore E, Goltzman D, Ganz T, Nemeth E, Salusky IB. Effects of dietary iron intake and chronic kidney disease on fibroblast growth factor 23 metabolism in wild-type and hepcidin knockout mice. Am J Physiol Renal Physiol 2016; 311:F1369-F1377. [PMID: 27733366 PMCID: PMC5210202 DOI: 10.1152/ajprenal.00281.2016] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Revised: 10/05/2016] [Accepted: 10/05/2016] [Indexed: 12/17/2022] Open
Abstract
In the setting of normal kidney function, iron deficiency is associated with increased FGF23 production and cleavage, altering circulating FGF23 levels. Our objective was to determine how chronic kidney disease (CKD) and dietary iron intake affect FGF23 production and metabolism in wild-type (WT) and hepcidin knockout (HKO) mice. For 8 wk, the mice were fed diets that contained adenine (to induce CKD) or no adenine (control group), with either low-iron (4 ppm) or standard-iron (335 ppm) concentrations. The low-iron diet induced iron deficiency anemia in both the WT and HKO mice. Among the WT mice, in both the control and CKD groups, a low-iron compared with a standard-iron diet increased bone Fgf23 mRNA expression, C-terminal FGF23 (cFGF23) levels, and FGF23 cleavage as manifested by a lower percentage intact FGF23 (iFGF23). Independent of iron status, CKD was associated with inhibition of FGF23 cleavage. Similar results were observed in the HKO control and CKD groups. Dietary iron content was more influential on FGF23 parameters than the presence or absence of hepcidin. In the CKD mice (WT and HKO, total n = 42), independent of the effects of serum phosphate, iron deficiency was associated with increased FGF23 production but also greater cleavage, whereas worse kidney function was associated with increased FGF23 production but decreased cleavage. Therefore, in both the WT and HKO mouse models, dietary iron content and CKD affected FGF23 production and metabolism.
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Affiliation(s)
- Mark R Hanudel
- Department of Pediatrics, David Geffen School of Medicine at UCLA, Los Angeles, California;
| | - Kristine Chua
- Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, California; and
| | - Maxime Rappaport
- Department of Pediatrics, David Geffen School of Medicine at UCLA, Los Angeles, California
| | - Victoria Gabayan
- Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, California; and
| | - Erika Valore
- Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, California; and
| | - David Goltzman
- Department of Medicine, McGill University Health Centre and McGill University, Montreal, Quebec, Canada
| | - Tomas Ganz
- Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, California; and
| | - Elizabeta Nemeth
- Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, California; and
| | - Isidro B Salusky
- Department of Pediatrics, David Geffen School of Medicine at UCLA, Los Angeles, California
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80
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Lakhal-Littleton S, Wolna M, Chung YJ, Christian HC, Heather LC, Brescia M, Ball V, Diaz R, Santos A, Biggs D, Clarke K, Davies B, Robbins PA. An essential cell-autonomous role for hepcidin in cardiac iron homeostasis. eLife 2016; 5. [PMID: 27897970 PMCID: PMC5176354 DOI: 10.7554/elife.19804] [Citation(s) in RCA: 134] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Accepted: 11/24/2016] [Indexed: 12/16/2022] Open
Abstract
Hepcidin is the master regulator of systemic iron homeostasis. Derived primarily from the liver, it inhibits the iron exporter ferroportin in the gut and spleen, the sites of iron absorption and recycling respectively. Recently, we demonstrated that ferroportin is also found in cardiomyocytes, and that its cardiac-specific deletion leads to fatal cardiac iron overload. Hepcidin is also expressed in cardiomyocytes, where its function remains unknown. To define the function of cardiomyocyte hepcidin, we generated mice with cardiomyocyte-specific deletion of hepcidin, or knock-in of hepcidin-resistant ferroportin. We find that while both models maintain normal systemic iron homeostasis, they nonetheless develop fatal contractile and metabolic dysfunction as a consequence of cardiomyocyte iron deficiency. These findings are the first demonstration of a cell-autonomous role for hepcidin in iron homeostasis. They raise the possibility that such function may also be important in other tissues that express both hepcidin and ferroportin, such as the kidney and the brain. DOI:http://dx.doi.org/10.7554/eLife.19804.001 Many proteins inside cells require iron to work properly, and so this mineral is an essential part of the diets of most mammals. However, because too much iron in the body is also bad for health, mammals possess several proteins whose role is to maintain the balance of iron. Two proteins in particular, called hepcidin and ferroportin, are thought to be important in this process. Some ferroportin is found in the cells that line the gut (where iron is absorbed into the body) and is required to release this iron into the bloodstream. It is also found in the spleen, which is where iron is removed from old red blood cells so that it can be recycled. The liver produces hepcidin to control when ferroportin is active in the gut and spleen. Both hepcidin and ferroportin are also found in heart cells. In 2015, a study reported that that heart ferroportin plays an important role in heart activity. However, it was not clear what role hepcidin plays in this organ. Now, Lakhal-Littleton et al. – including many of the researchers from the previous work – have genetically engineered mice such that they specifically lacked heart hepcidin, or had a version of ferroportin in their heart that does not respond to hepcidin. The experiments show that these changes caused fatal heart failure in the mice because ferroportin releases iron from heart cells in an uncontrolled manner. Lakhal-Littleton et al. were able to prevent heart failure by injecting the animals with iron directly into the bloodstream. These findings show that hepcidin produced outside the liver has a role in controlling the levels of iron in the body’s organs. Other organs such as the brain, kidney and placenta all have their own forms of hepcidin and ferroportin; further work could investigate the roles of these proteins. Finally, another challenge for the future will be to test whether new drugs that are being developed to block or mimic hepcidin from the liver have the potential to treat heart conditions in humans. DOI:http://dx.doi.org/10.7554/eLife.19804.002
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Affiliation(s)
- Samira Lakhal-Littleton
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Magda Wolna
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Yu Jin Chung
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Helen C Christian
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Lisa C Heather
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Marcella Brescia
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Vicky Ball
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Rebeca Diaz
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Ana Santos
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Daniel Biggs
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Kieran Clarke
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Benjamin Davies
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Peter A Robbins
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
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81
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Ferro E, Di Pietro A, Visalli G, Piraino B, Salpietro C, La Rosa MA. Soluble hemojuvelin in transfused and untransfused thalassaemic subjects. Eur J Haematol 2016; 98:67-74. [PMID: 27440164 DOI: 10.1111/ejh.12786] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/16/2016] [Indexed: 12/11/2022]
Abstract
OBJECTIVE The hemojuvelin-bone morphogenetic protein axis is the principal iron-dependent mechanism of hepcidin regulation. The determination of soluble hemojuvelin (sHJV) levels could allow for a better understanding of the pathophysiological mechanisms of hepcidin regulation in thalassaemia. METHOD We have assessed sHJV in 45 transfused and 15 untransfused thalassaemic patients in comparison with 15 healthy subjects, evaluating its relationships with some parameters of iron overload, anaemia and erythropoiesis. RESULTS Untransfused thalassaemic patients had more severe anaemia and erythropoietic activity, while in transfused patients, the transfused RBCs reduced % reticulocytes and sTfR, increased serum indices of iron overload and iron stores in the liver (low MRI T2* values). sHJV levels were higher in patients than in controls and in untransfused in comparison with transfused patients. In the transfused group, we also found that sHJV values are significantly related to serum ferritin, cardiac MRI T2* and growth differentiation factor 15 and are sensitive to hepatitis C virus infection. CONCLUSION These results suggest that sHJV synthesis seems to be affected by an erythropoietic/hypoxic signal in untransfused patients that have severe anaemia, while in regularly transfused subjects, it is influenced by iron stores.
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Affiliation(s)
- Elisa Ferro
- Department of Human Pathology of Adult and Developmental Age 'Gaetano Barresi', University Hospital of Messina, Messina, Italy
| | - Angela Di Pietro
- Department of Biomedical and Dental Sciences and Morphofunctional Imaging, University of Messina, Messina, Italy
| | - Giuseppa Visalli
- Department of Biomedical and Dental Sciences and Morphofunctional Imaging, University of Messina, Messina, Italy
| | - Basilia Piraino
- Department of Human Pathology of Adult and Developmental Age 'Gaetano Barresi', University Hospital of Messina, Messina, Italy
| | - Carmelo Salpietro
- Department of Human Pathology of Adult and Developmental Age 'Gaetano Barresi', University Hospital of Messina, Messina, Italy
| | - Maria Angela La Rosa
- Department of Human Pathology of Adult and Developmental Age 'Gaetano Barresi', University Hospital of Messina, Messina, Italy
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82
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Camaschella C, Pagani A, Nai A, Silvestri L. The mutual control of iron and erythropoiesis. Int J Lab Hematol 2016; 38 Suppl 1:20-6. [PMID: 27161430 DOI: 10.1111/ijlh.12505] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/04/2016] [Indexed: 12/13/2022]
Abstract
BACKGROUND Iron is essential for hemoglobin synthesis during terminal erythropoiesis. To supply adequate iron the carrier transferrin is required together with transferrin receptor endosomal cycle and normal mitochondrial iron utilization. Iron and iron protein deficiencies result in different types of anemia. Iron-deficiency anemia is the commonest anemia worldwide due to increased requirements, malnutrition, chronic blood losses and malabsorption. Mutations of transferrin, transferrin receptor cycle proteins, enzymes of the first step of heme synthesis and iron sulfur cluster biogenesis lead to rare anemias, usually accompanied by iron overload. Hepcidin plays an indirect role in erythropoiesis by controlling plasma iron. Inappropriately high hepcidin levels characterize the rare genetic iron-refractory iron-deficiency anemia (IRIDA) and the common anemia of chronic disease. Iron modulates both effective and ineffective erythropoiesis: iron restriction reduces heme and alpha-globin synthesis that may be of benefit in thalassemia. MATERIAL AND METHODS This review relies on the analysis of the most recent literature and personal data. RESULTS Erythropoiesis controls iron homeostasis, by releasing erythroferrone that inhibits hepcidin transcription to increase iron acquisition in iron deficiency, hypoxia and EPO treatment. Erythroferrone, produced by EPO-stimulated erythropoiesis, inhibits hepcidin only when the activity of BMP/SMAD pathway is low, suggesting that EPO somehow modulates the latter signaling. Erythroblasts sense circulating iron through the second transferrin receptor (TFR2) that, in animal models, modulates the sensitivity of the erythroid cells to EPO. DISCUSSION The advanced knowledge of the regulation of systemic iron homeostasis and erythropoiesis-mediated hepcidin regulation is leading to the development of targeted therapies for anemias and iron disorders.
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Affiliation(s)
- C Camaschella
- Vita Salute University and San Raffaele Scientific Institute, Milano, Italy
| | - A Pagani
- Vita Salute University and San Raffaele Scientific Institute, Milano, Italy
| | - A Nai
- Vita Salute University and San Raffaele Scientific Institute, Milano, Italy
| | - L Silvestri
- Vita Salute University and San Raffaele Scientific Institute, Milano, Italy
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83
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Zhao N, Maxson JE, Zhang RH, Wahedi M, Enns CA, Zhang AS. Neogenin Facilitates the Induction of Hepcidin Expression by Hemojuvelin in the Liver. J Biol Chem 2016; 291:12322-35. [PMID: 27072365 DOI: 10.1074/jbc.m116.721191] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Indexed: 01/24/2023] Open
Abstract
Hemojuvelin (HJV) regulates iron homeostasis by direct interaction with bone morphogenetic protein (BMP) ligands to induce hepcidin expression through the BMP signaling pathway in the liver. Crystallography studies indicate that HJV can simultaneously bind to both BMP2 and the ubiquitously expressed cell surface receptor neogenin. However, the role of the neogenin-HJV interaction in the function of HJV is unknown. Here we identify a mutation in HJV that specifically lowers its interaction with neogenin. Expression of this mutant Hjv in the liver of Hjv(-/-) mice dramatically attenuated its induction of BMP signaling and hepcidin mRNA, suggesting that interaction with neogenin is critical for the iron regulatory function of HJV. Further studies revealed that neogenin co-immunoprecipitated with ALK3, an essential type-I BMP receptor for hepatic hepcidin expression. Neogenin has also been shown to facilitate the cleavage of HJV by furin in transfected cells. Surprisingly, although cleavage of HJV by furin has been implicated in the regulation of HJV function in cell culture models and furin-cleaved soluble Hjv is detectable in the serum of mice, mutating the furin cleavage site did not alter the stimulation of hepcidin expression by Hjv in mice. In vivo studies validated the important role of HJV-BMP interaction for Hjv stimulation of BMP signaling and hepcidin expression. Together these data support a model in which neogenin acts as a scaffold to facilitate assembly of the HJV·BMP·BMP receptor complex to induce hepcidin expression.
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Affiliation(s)
- Ningning Zhao
- From the Department of Cell, Developmental, and Cancer Biology, Oregon Health & Science University, Portland, Oregon 97239
| | - Julia E Maxson
- From the Department of Cell, Developmental, and Cancer Biology, Oregon Health & Science University, Portland, Oregon 97239
| | - Richard H Zhang
- From the Department of Cell, Developmental, and Cancer Biology, Oregon Health & Science University, Portland, Oregon 97239
| | - Mastura Wahedi
- From the Department of Cell, Developmental, and Cancer Biology, Oregon Health & Science University, Portland, Oregon 97239
| | - Caroline A Enns
- From the Department of Cell, Developmental, and Cancer Biology, Oregon Health & Science University, Portland, Oregon 97239
| | - An-Sheng Zhang
- From the Department of Cell, Developmental, and Cancer Biology, Oregon Health & Science University, Portland, Oregon 97239
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84
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Guillemot J, Seidah NG. PACE4 (PCSK6): another proprotein convertase link to iron homeostasis? Haematologica 2016; 100:e377. [PMID: 26341526 DOI: 10.3324/haematol.2015.127175] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Affiliation(s)
- Johann Guillemot
- Laboratory of Biochemical Neuroendocrinology, Clinical Research Institute of Montreal (IRCM), affiliated to the University of Montreal, Montreal, Quebec, H2W 1R7, Canada
| | - Nabil G Seidah
- Laboratory of Biochemical Neuroendocrinology, Clinical Research Institute of Montreal (IRCM), affiliated to the University of Montreal, Montreal, Quebec, H2W 1R7, Canada
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85
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Yousaf F, Spinowitz B. Hypoxia-Inducible Factor Stabilizers: a New Avenue for Reducing BP While Helping Hemoglobin? Curr Hypertens Rep 2016; 18:23. [DOI: 10.1007/s11906-016-0629-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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86
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Belaidi AA, Bush AI. Iron neurochemistry in Alzheimer's disease and Parkinson's disease: targets for therapeutics. J Neurochem 2016; 139 Suppl 1:179-197. [DOI: 10.1111/jnc.13425] [Citation(s) in RCA: 324] [Impact Index Per Article: 40.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Revised: 10/24/2015] [Accepted: 11/03/2015] [Indexed: 12/12/2022]
Affiliation(s)
- Abdel A. Belaidi
- The Florey Institute for Neuroscience and Mental Health; The University of Melbourne; Parkville Vic. Australia
| | - Ashley I. Bush
- The Florey Institute for Neuroscience and Mental Health; The University of Melbourne; Parkville Vic. Australia
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87
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Li K, Reichmann H. Role of iron in neurodegenerative diseases. J Neural Transm (Vienna) 2016; 123:389-99. [PMID: 26794939 DOI: 10.1007/s00702-016-1508-7] [Citation(s) in RCA: 81] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Accepted: 01/12/2016] [Indexed: 01/01/2023]
Abstract
Currently, we still lack effective measures to modify disease progression in neurodegenerative diseases. Iron-containing proteins play an essential role in many fundamental biological processes in the central nervous system. In addition, iron is a redox-active ion and can induce oxidative stress in the cell. Although the causes and pathology hallmarks of different neurodegenerative diseases vary, iron dyshomeostasis, oxidative stress and mitochondrial injury constitute a common pathway to cell death in several neurodegenerative diseases. MRI is capable of depicting iron content in the brain, and serves as a potential biomarker for early and differential diagnosis, tracking disease progression and evaluating the effectiveness of neuroprotective therapy. Iron chelators have shown their efficacy against neurodegeneration in a series of animal models, and been applied in several clinical trials. In this review, we summarize recent developments on iron dyshomeostasis in Parkinson's disease, Alzheimer's disease, Friedreich ataxia, and Huntington's disease.
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Affiliation(s)
- Kai Li
- Center of Clinical Neuroscience, University Hospital Carl Gustav Carus, Dresden University of Technology, Fetscherstr. 74, 01307, Dresden, Germany.
| | - Heinz Reichmann
- Department of Neurology, University Hospital Carl Gustav Carus, Dresden University of Technology, Fetscherstr. 74, 01307, Dresden, Germany
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88
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Blanchette NL, Manz DH, Torti FM, Torti SV. Modulation of hepcidin to treat iron deregulation: potential clinical applications. Expert Rev Hematol 2015; 9:169-86. [PMID: 26669208 DOI: 10.1586/17474086.2016.1124757] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The secreted peptide hormone hepcidin regulates systemic and local iron homeostasis through degradation of the iron exporter ferroportin. Dysregulation of hepcidin leads to altered iron homeostasis and development of pathological disorders including hemochromatosis, and iron loading and iron restrictive anemias. Therapeutic modulation of hepcidin is a promising method to ameliorate these conditions. Several approaches have been taken to enhance or reduce the effects of hepcidin in vitro and in vivo. Based on these approaches, hepcidin modulating drugs have been developed and are undergoing clinical evaluation. In this article we review the rationale for development of these drugs, the data concerning their safety and efficacy, their therapeutic uses, and potential future prospects.
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Affiliation(s)
- Nicole L Blanchette
- a Department of Molecular Biology and Biophysics , University of Connecticut Health , Farmington , CT , USA
| | - David H Manz
- a Department of Molecular Biology and Biophysics , University of Connecticut Health , Farmington , CT , USA.,b School of Dental Medicine , University of Connecticut Health , Farmington , CT , USA
| | - Frank M Torti
- c Department of Medicine , University of Connecticut Health , Farmington , CT , USA
| | - Suzy V Torti
- a Department of Molecular Biology and Biophysics , University of Connecticut Health , Farmington , CT , USA
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89
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Recalcati S, Gammella E, Cairo G. New perspectives on the molecular basis of the interaction between oxygen homeostasis and iron metabolism. HYPOXIA 2015; 3:93-103. [PMID: 27774486 PMCID: PMC5045093 DOI: 10.2147/hp.s83537] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Oxygen and iron are two elements closely related from a (bio)chemical point of view. Moreover, they share the characteristic of being indispensable for life, while also being potentially toxic. Therefore, their level is strictly monitored, and sophisticated pathways have evolved to face variations in either element. In addition, the expression of proteins involved in iron and oxygen metabolism is mainly controlled by a complex interplay of proteins that sense both iron levels and oxygen availability (ie, prolyl hydroxylases, hypoxia inducible factors, and iron regulatory proteins), and in turn activate feedback mechanisms to re-establish homeostasis. In this review, we describe how cells and organisms utilize these intricate networks to regulate responses to changes in oxygen and iron levels. We also explore the role of these pathways in some pathophysiological settings.
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Affiliation(s)
- Stefania Recalcati
- Department of Biomedical Sciences for Health, University of Milan, Milan, Italy
| | - Elena Gammella
- Department of Biomedical Sciences for Health, University of Milan, Milan, Italy
| | - Gaetano Cairo
- Department of Biomedical Sciences for Health, University of Milan, Milan, Italy
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90
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Camaschella C, Nai A. Ineffective erythropoiesis and regulation of iron status in iron loading anaemias. Br J Haematol 2015; 172:512-23. [PMID: 26491866 DOI: 10.1111/bjh.13820] [Citation(s) in RCA: 109] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The definition 'iron loading anaemias' encompasses a group of inherited and acquired anaemias characterized by ineffective erythropoiesis, low hepcidin levels, excessive iron absorption and secondary iron overload. Non-transfusion-dependent β-thalassaemia is the paradigmatic example of these conditions that include dyserythropoietic and sideroblastic anaemias and some forms of myelodysplasia. Interrupting the vicious cycle between ineffective erythropoiesis and iron overload may be of therapeutic benefit in all these diseases. Induction of iron restriction by means of transferrin infusions, minihepcidins or manipulation of the hepcidin pathway prevents iron overload, redistributes iron from parenchymal cells to macrophage stores and partially controls anaemia in β-thalassaemic mice. Inhibition of ineffective erythropoiesis by activin ligand traps improves anaemia and iron overload in the same models. Targeting iron loading or ineffective erythropoiesis shows promise in preclinical studies; activin ligand traps are in clinical trials with promising results and may be useful in patients with ineffective erythropoiesis.
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Affiliation(s)
- Clara Camaschella
- Division of Genetics and Cell Biology, San Raffaele Scientific Institute, Vita Salute University, Milano, Italy
| | - Antonella Nai
- Division of Genetics and Cell Biology, San Raffaele Scientific Institute, Vita Salute University, Milano, Italy
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91
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Guerreiro C, Silva B, Crespo ÂC, Marques L, Costa S, Timóteo Â, Marcelino E, Maruta C, Vilares A, Matos M, Couto FS, Faustino P, Verdelho A, Guerreiro M, Herrero A, Costa C, de Mendonça A, Martins M, Costa L. Decrease in APP and CP mRNA expression supports impairment of iron export in Alzheimer's disease patients. Biochim Biophys Acta Mol Basis Dis 2015. [PMID: 26209012 DOI: 10.1016/j.bbadis.2015.07.017] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Alzheimer's disease (AD) is a neurodegenerative disorder of still unknown etiology and the leading cause of dementia worldwide. Besides its main neuropathological hallmarks, a dysfunctional homeostasis of transition metals has been reported to play a pivotal role in the pathogenesis of this disease. Dysregulation of iron (Fe) metabolism in AD has been suggested, particularly at the level of cellular iron efflux. Herein, we intended to further clarify the molecular mechanisms underlying Fe homeostasis in AD. In order to achieve this goal, the expression of specific Fe metabolism-related genes directly involved in Fe regulation and export was assessed in peripheral blood mononuclear cells (PBMCs) from 73AD patients and 74 controls by quantitative PCR. The results obtained showed a significant decrease in the expression of aconitase 1 (ACO1; P=0.007); ceruloplasmin (CP; P<0.001) and amyloid-beta precursor protein (APP; P=0.006) genes in AD patients compared with healthy volunteers. These observations point out to a significant downregulation in the expression of genes associated with ferroportin-mediated cellular Fe export in PBMCs from AD patients, when compared to controls. Taken together, these findings support previous studies suggesting impairment of Fe homeostasis in AD, which may lead to cellular Fe retention and oxidative stress, a typical feature of this disease.
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Affiliation(s)
- Cláudia Guerreiro
- Health Promotion and Prevention of Noncommunicable Diseases Department, Instituto Nacional de Saúde Doutor Ricardo Jorge, Lisboa, Portugal
| | - Bruno Silva
- Human Genetics Department, Instituto Nacional de Saúde Dr. Ricardo Jorge, Lisboa, Portugal
| | - Ângela C Crespo
- Health Promotion and Prevention of Noncommunicable Diseases Department, Instituto Nacional de Saúde Doutor Ricardo Jorge, Lisboa, Portugal; Instituto Gulbenkian de Ciência, Oeiras, Portugal
| | - Liliana Marques
- Health Promotion and Prevention of Noncommunicable Diseases Department, Instituto Nacional de Saúde Doutor Ricardo Jorge, Lisboa, Portugal; University of Lisboa, Faculty of Sciences, BioISI-Biosystems & Integrative Sciences Institute, Campo Grande, Lisboa, Portugal
| | - Sónia Costa
- Neurology Department, Hospital Prof. Dr. Fernando Fonseca, E.P.E., Amadora, Portugal
| | - Ângela Timóteo
- Neurology Department, Hospital Prof. Dr. Fernando Fonseca, E.P.E., Amadora, Portugal
| | - Erica Marcelino
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
| | - Carolina Maruta
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
| | - Arminda Vilares
- Health Promotion and Prevention of Noncommunicable Diseases Department, Instituto Nacional de Saúde Doutor Ricardo Jorge, Lisboa, Portugal
| | - Mafalda Matos
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
| | - Frederico Simões Couto
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
| | - Paula Faustino
- Human Genetics Department, Instituto Nacional de Saúde Dr. Ricardo Jorge, Lisboa, Portugal
| | - Ana Verdelho
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
| | - Manuela Guerreiro
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
| | - Ana Herrero
- Neurology Department, Hospital Prof. Dr. Fernando Fonseca, E.P.E., Amadora, Portugal
| | - Cristina Costa
- Neurology Department, Hospital Prof. Dr. Fernando Fonseca, E.P.E., Amadora, Portugal
| | - Alexandre de Mendonça
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
| | - Madalena Martins
- Instituto Gulbenkian de Ciência, Oeiras, Portugal; Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal.
| | - Luciana Costa
- Health Promotion and Prevention of Noncommunicable Diseases Department, Instituto Nacional de Saúde Doutor Ricardo Jorge, Lisboa, Portugal; University of Lisboa, Faculty of Sciences, BioISI-Biosystems & Integrative Sciences Institute, Campo Grande, Lisboa, Portugal.
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92
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Abstract
Anemia in the setting of chronic inflammatory disorders is a very frequent clinical condition, which is, however, often neglected or not properly treated given the problems often caused by the diseases underlying the development of anemia. Mechanistically, anemia is mainly caused by inflammation-driven retention of iron in macrophages making the metal unavailable for heme synthesis in the course of erythropoiesis, and further by impaired biological activity of the red blood cell hormone erythropoietin and the reduced proliferative capacity of erythroid progenitor cells. Anemia can be aggravated by chronic blood loss, as found in subjects with gastrointestinal cancers, inflammatory or infectious bowel disease, or iatrogenic blood loss in the setting of dialysis, all resulting in true iron deficiency. The identification of such patients is a clinical necessity because these individuals need contrasting therapies in comparison to subjects suffering from only classical anemia of chronic disorders. The diagnosis is challenging because no state of the art laboratory test is currently available that can clearly separate patients with inflammatory anemia from those with additional true iron deficiency. However, based on our expanding knowledge on the pathophysiology of inflammatory anemia, new diagnostic markers, including the iron-regulatory hormone hepcidin, and hematologic parameters emerge. Apart from traditional anemia treatments such as blood transfusions, recombinant erythropoietin, and iron, including new high-molecular-weight formulations, new therapeutics are currently under preclinical and clinical evaluation. These novel compounds aim at correcting anemia by multiple pathways, including antagonizing the inflammation- and hepcidin-driven retention of iron in the monocyte-macrophage system and thereby promoting the supply of iron for erythropoiesis or by stimulating the endogenous formation of erythopoietin via stabilization of hypoxia-regulated factors.
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Affiliation(s)
- Guenter Weiss
- Department of Internal Medicine VI, Infectious Diseases, Immunology, Rheumatology, Pneumology, Medical University of Innsbruck, Innsbruck, Austria.
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93
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Abstract
Improved understanding of the oxygen-dependent regulation of erythropoiesis has provided new insights into the pathogenesis of anaemia associated with renal failure and has led to the development of novel therapeutic agents for its treatment. Hypoxia-inducible factor (HIF)-2 is a key regulator of erythropoiesis and iron metabolism. HIF-2 is activated by hypoxic conditions and controls the production of erythropoietin by renal peritubular interstitial fibroblast-like cells and hepatocytes. In anaemia associated with renal disease, erythropoiesis is suppressed due to inadequate erythropoietin production in the kidney, inflammation and iron deficiency; however, pharmacologic agents that activate the HIF axis could provide a physiologic approach to the treatment of renal anaemia by mimicking hypoxia responses that coordinate erythropoiesis with iron metabolism. This Review discusses the functional inter-relationships between erythropoietin, iron and inflammatory mediators under physiologic conditions and in relation to the pathogenesis of renal anaemia, as well as recent insights into the molecular and cellular basis of erythropoietin production in the kidney. It furthermore provides a detailed overview of current clinical experience with pharmacologic activators of HIF signalling as a novel comprehensive and physiologic approach to the treatment of anaemia.
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94
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Silva B, Faustino P. An overview of molecular basis of iron metabolism regulation and the associated pathologies. Biochim Biophys Acta Mol Basis Dis 2015; 1852:1347-59. [PMID: 25843914 DOI: 10.1016/j.bbadis.2015.03.011] [Citation(s) in RCA: 182] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Revised: 03/05/2015] [Accepted: 03/27/2015] [Indexed: 12/18/2022]
Abstract
Iron is essential for several vital biological processes. Its deficiency or overload drives to the development of several pathologies. To maintain iron homeostasis, the organism controls the dietary iron absorption by enterocytes, its recycling by macrophages and storage in hepatocytes. These processes are mainly controlled by hepcidin, a liver-derived hormone which synthesis is regulated by iron levels, inflammation, infection, anemia and erythropoiesis. Besides the systemic regulation of iron metabolism mediated by hepcidin, cellular regulatory processes also occur. Cells are able to regulate themselves the expression of the iron metabolism-related genes through different post-transcriptional mechanisms, such as the alternative splicing, microRNAs, the IRP/IRE system and the proteolytic cleavage. Whenever those mechanisms are disturbed, due to genetic or environmental factors, iron homeostasis is disrupted and iron related pathologies may arise.
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Affiliation(s)
- Bruno Silva
- Departamento de Genética Humana, Instituto Nacional de Saúde Dr. Ricardo Jorge, Lisboa, Portugal
| | - Paula Faustino
- Departamento de Genética Humana, Instituto Nacional de Saúde Dr. Ricardo Jorge, Lisboa, Portugal.
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95
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Abstract
Iron, an essential nutrient, is required for many diverse biological processes. The absence of a defined pathway to excrete excess iron makes it essential for the body to regulate the amount of iron absorbed; a deficiency could lead to iron deficiency and an excess to iron overload and associated disorders such as anaemia and haemochromatosis respectively. This regulation is mediated by the iron-regulatory hormone hepcidin. Hepcidin binds to the only known iron export protein, ferroportin (FPN), inducing its internalization and degradation, thus limiting the amount of iron released into the blood. The major factors that are implicated in hepcidin regulation include iron stores, hypoxia, inflammation and erythropoiesis. The present review summarizes our present knowledge about the molecular mechanisms and signalling pathways contributing to hepcidin regulation by these factors.
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96
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Endocrine and bone complications in β-thalassemia intermedia: current understanding and treatment. BIOMED RESEARCH INTERNATIONAL 2015; 2015:813098. [PMID: 25834825 PMCID: PMC4365366 DOI: 10.1155/2015/813098] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 07/20/2014] [Revised: 09/15/2014] [Accepted: 10/07/2014] [Indexed: 01/19/2023]
Abstract
Thalassemia intermedia (TI), also known as nontransfusion dependent thalassemia (NTDT), is a type of thalassemia where affected patients do not require lifelong regular transfusions for survival but may require occasional or even frequent transfusions in certain clinical settings and for defined periods of time. NTDT encompasses three distinct clinical forms: β-thalassemia intermedia (β-TI), Hb E/β-thalassemia, and α-thalassemia intermedia (Hb H disease). Over the past decade, our understanding of the molecular features, pathophysiology, and complications of NTDT particularly β-TI has increased tremendously but data on optimal treatment of disease and its various complications are still lacking. In this paper, we shall review a group of commonly encountered complications in β-TI, mainly endocrine and bone complications.
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97
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Rausa M, Ghitti M, Pagani A, Nai A, Campanella A, Musco G, Camaschella C, Silvestri L. Identification of TMPRSS6 cleavage sites of hemojuvelin. J Cell Mol Med 2015; 19:879-88. [PMID: 25704252 PMCID: PMC4395201 DOI: 10.1111/jcmm.12462] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2014] [Accepted: 09/19/2014] [Indexed: 12/11/2022] Open
Abstract
Hemojuvelin (HJV), the coreceptor of the BMP-SMAD pathway that up-regulates hepcidin transcription, is a repulsive guidance molecule (RGMc) which undergoes a complex intracellular processing. Following autoproteolysis, it is exported to the cell surface both as a full-length and a heterodimeric protein. In vitro membrane HJV (m-HJV) is cleaved by the transmembrane serine protease TMPRSS6 to attenuate signalling and to inhibit hepcidin expression. In this study, we investigated the number and position of HJV cleavage sites by mutagenizing arginine residues (R), potential TMPRSS6 targets, to alanine (A). We analysed translation and membrane expression of HJV R mutants and the pattern of fragments they release in the culture media in the presence of TMPRSS6. Abnormal fragments were observed for mutants at arginine 121, 176, 218, 288 and 326. Considering that all variants, except HJVR121A, lack autoproteolytic activity and some (HJVR176A and HJVR288A) are expressed at reduced levels on cell surface, we identified the fragments originating from either full-length or heterodimeric proteins and defined the residues 121 and 326 as the TMPRSS6 cleavage sites in both isoforms. Using the N-terminal FLAG-tagged HJV, we showed that residue 121 is critical also in the rearrangement of the N-terminal heterodimeric HJV. Exploiting the recently reported RGMb crystallographic structure, we generated a model of HJV that was used as input structure for all-atoms molecular dynamics simulation in explicit solvent. As assessed by in silico studies, we concluded that some arginines in the von Willebrand domain appear TMPRSS6 insensitive, likely because of partial protein structure destabilization.
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Affiliation(s)
- Marco Rausa
- Division of Genetics and Cell Biology, IRCCS Ospedale San Raffaele, Milan, Italy; Vita Salute University, Milan, Italy
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98
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The iron-regulatory hormone hepcidin: A possible therapeutic target? Pharmacol Ther 2015; 146:35-52. [DOI: 10.1016/j.pharmthera.2014.09.004] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2014] [Accepted: 09/02/2014] [Indexed: 01/19/2023]
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99
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Pagani A, Vieillevoye M, Nai A, Rausa M, Ladli M, Lacombe C, Mayeux P, Verdier F, Camaschella C, Silvestri L. Regulation of cell surface transferrin receptor-2 by iron-dependent cleavage and release of a soluble form. Haematologica 2015; 100:458-65. [PMID: 25637053 DOI: 10.3324/haematol.2014.118521] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Transferrin receptor-2 is a transmembrane protein whose expression is restricted to hepatocytes and erythroid cells. Transferrin receptor-2 has a regulatory function in iron homeostasis, since its inactivation causes systemic iron overload. Hepatic transferrin receptor-2 participates in iron sensing and is involved in hepcidin activation, although the mechanism remains unclear. Erythroid transferrin receptor-2 associates with and stabilizes erythropoietin receptors on the erythroblast surface and is essential to control erythrocyte production in iron deficiency. We identified a soluble form of transferrin receptor-2 in the media of transfected cells and showed that cultured human erythroid cells release an endogenous soluble form. Soluble transferrin receptor-2 originates from a cleavage of the cell surface protein, which is inhibited by diferric transferrin in a dose-dependent manner. Accordingly, the shedding of the transferrin receptor-2 variant G679A, mutated in the Arginine-Glycine-Aspartic acid motif and unable to bind diferric transferrin, is not modulated by the ligand. This observation links the process of transferrin receptor-2 removal from the plasma membrane to iron homeostasis. Soluble transferrin receptor-2 does not affect the binding of erythropoietin to erythropoietin receptor or the consequent signaling and partially inhibits hepcidin promoter activation only in vitro. Whether it is a component of the signals released by erythropoiesis in iron deficiency remains to be investigated. Our results indicate that membrane transferrin receptor-2, a sensor of circulating iron, is released from the cell membrane in iron deficiency.
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Affiliation(s)
- Alessia Pagani
- Vita Salute San Raffaele University, Milan, Italy Division of Genetics and Cell Biology, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Maud Vieillevoye
- Institut Cochin, INSERM, U1016, Université Paris Descartes, CNRS (UMR8104), Paris, France Ligue National contre le Cancer, Paris, France
| | - Antonella Nai
- Vita Salute San Raffaele University, Milan, Italy Division of Genetics and Cell Biology, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Marco Rausa
- Vita Salute San Raffaele University, Milan, Italy Division of Genetics and Cell Biology, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Meriem Ladli
- Institut Cochin, INSERM, U1016, Université Paris Descartes, CNRS (UMR8104), Paris, France Ligue National contre le Cancer, Paris, France
| | - Catherine Lacombe
- Institut Cochin, INSERM, U1016, Université Paris Descartes, CNRS (UMR8104), Paris, France Ligue National contre le Cancer, Paris, France
| | - Patrick Mayeux
- Institut Cochin, INSERM, U1016, Université Paris Descartes, CNRS (UMR8104), Paris, France Ligue National contre le Cancer, Paris, France
| | | | - Clara Camaschella
- Vita Salute San Raffaele University, Milan, Italy Division of Genetics and Cell Biology, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Laura Silvestri
- Vita Salute San Raffaele University, Milan, Italy Division of Genetics and Cell Biology, IRCCS San Raffaele Scientific Institute, Milan, Italy
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100
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Abstract
Iron and oxygen metabolism are intimately linked with one another.
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Affiliation(s)
- Robert J. Simpson
- Diabetes and Nutritional Sciences
- School of Medicine
- Kings College London
- , UK
| | - Andrew T. McKie
- Diabetes and Nutritional Sciences
- School of Medicine
- Kings College London
- , UK
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