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Srole DN, Jung G, Waring AJ, Nemeth E, Ganz T. Characterization of erythroferrone structural domains relevant to its iron-regulatory function. J Biol Chem 2023; 299:105374. [PMID: 37866631 PMCID: PMC10692919 DOI: 10.1016/j.jbc.2023.105374] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Revised: 09/29/2023] [Accepted: 10/12/2023] [Indexed: 10/24/2023] Open
Abstract
Iron delivery to the plasma is closely coupled to erythropoiesis, the production of red blood cells, as this process consumes most of the circulating plasma iron. In response to hemorrhage and other erythropoietic stresses, increased erythropoietin stimulates the production of the hormone erythroferrone (ERFE) by erythrocyte precursors (erythroblasts) developing in erythropoietic tissues. ERFE acts on the liver to inhibit bone morphogenetic protein (BMP) signaling and thereby decrease hepcidin production. Decreased circulating hepcidin concentrations then allow the release of iron from stores and increase iron absorption from the diet. Guided by evolutionary analysis and Alphafold2 protein complex modeling, we used targeted ERFE mutations, deletions, and synthetic ERFE segments together with cell-based bioassays and surface plasmon resonance to probe the structural features required for bioactivity and BMP binding. We define the ERFE active domain and multiple structural features that act together to entrap BMP ligands. In particular, the hydrophobic helical segment 81 to 86 and specifically the highly conserved tryptophan W82 in the N-terminal region are essential for ERFE bioactivity and Alphafold2 modeling places W82 between two tryptophans in its ligands BMP2, BMP6, and the BMP2/6 heterodimer, an interaction similar to those that bind BMPs to their cognate receptors. Finally, we identify the cationic region 96-107 and the globular TNFα-like domain 186-354 as structural determinants of ERFE multimerization that increase the avidity of ERFE for BMP ligands. Collectively, our results provide further insight into the ERFE-mediated inhibition of BMP signaling in response to erythropoietic stress.
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Affiliation(s)
- Daniel N Srole
- Department of Medicine, Center for Iron Disorders, David Geffen School of Medicine at UCLA, Los Angeles, California, USA; Molecular and Medical Pharmacology Graduate Program, Graduate Programs in Bioscience, Los Angeles, California, USA
| | - Grace Jung
- Department of Medicine, Center for Iron Disorders, David Geffen School of Medicine at UCLA, Los Angeles, California, USA
| | - Alan J Waring
- Department of Medicine, Harbor-UCLA Medical Center, Lundquist Institute, Los Angeles, California, USA
| | - Elizabeta Nemeth
- Department of Medicine, Center for Iron Disorders, David Geffen School of Medicine at UCLA, Los Angeles, California, USA
| | - Tomas Ganz
- Department of Medicine, Center for Iron Disorders, David Geffen School of Medicine at UCLA, Los Angeles, California, USA.
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Vinchi F, Asperti M, Marques O, Nai A, Silvestri L. Flavor of Iron at EHA2023: Novel Regulatory Mechanisms and Therapeutic Options for the Correction of Anemia. Hemasphere 2023; 7:e955. [PMID: 37799346 PMCID: PMC10550016 DOI: 10.1097/hs9.0000000000000955] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/07/2023] Open
Affiliation(s)
- Francesca Vinchi
- Iron Research Program, Lindsley Kimball Research Institute, New York Blood Center, New York City, NY, USA
- Department of Pathology and Laboratory Medicine, Weill Cornell Medicine, New York City, NY, USA
| | - Michela Asperti
- Department of Molecular and Translational Medicine, University of Brescia, Italy
| | - Oriana Marques
- Department of Pediatric Oncology, Hematology and Immunology and Hopp Children Cancer Center, University Hospital Heidelberg, Germany
- Molecular Medicine Partnership Unit, European Molecular Biology Laboratory (EMBL) and University of Heidelberg, Germany
| | - Antonella Nai
- Regulation of Iron Metabolism Unit, Division of Genetics and Cell Biology, San Raffaele Scientific Institute, Milan, Italy
- School of Medicine, Vita-Salute San Raffaele University, Milan, Italy
| | - Laura Silvestri
- Regulation of Iron Metabolism Unit, Division of Genetics and Cell Biology, San Raffaele Scientific Institute, Milan, Italy
- School of Medicine, Vita-Salute San Raffaele University, Milan, Italy
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3
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Hogwood J, Mulloy B, Lever R, Gray E, Page CP. Pharmacology of Heparin and Related Drugs: An Update. Pharmacol Rev 2023; 75:328-379. [PMID: 36792365 DOI: 10.1124/pharmrev.122.000684] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Revised: 11/04/2022] [Accepted: 11/08/2022] [Indexed: 02/17/2023] Open
Abstract
Heparin has been used extensively as an antithrombotic and anticoagulant for close to 100 years. This anticoagulant activity is attributed mainly to the pentasaccharide sequence, which potentiates the inhibitory action of antithrombin, a major inhibitor of the coagulation cascade. More recently it has been elucidated that heparin exhibits anti-inflammatory effect via interference of the formation of neutrophil extracellular traps and this may also contribute to heparin's antithrombotic activity. This illustrates that heparin interacts with a broad range of biomolecules, exerting both anticoagulant and nonanticoagulant actions. Since our previous review, there has been an increased interest in these nonanticoagulant effects of heparin, with the beneficial role in patients infected with SARS2-coronavirus a highly topical example. This article provides an update on our previous review with more recent developments and observations made for these novel uses of heparin and an overview of the development status of heparin-based drugs. SIGNIFICANCE STATEMENT: This state-of-the-art review covers recent developments in the use of heparin and heparin-like materials as anticoagulant, now including immunothrombosis observations, and as nonanticoagulant including a role in the treatment of SARS-coronavirus and inflammatory conditions.
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Affiliation(s)
- John Hogwood
- Sackler Institute of Pulmonary Pharmacology, Institute of Pharmaceutical Science, King's College London, London, United Kingdom (B.M., E.G., C.P.P.); National Institute for Biological Standards and Control, South Mimms, Hertfordshire, United Kingdom (J.H., E.G.) and School of Pharmacy, University College London, London, United Kingdom (R.L.)
| | - Barbara Mulloy
- Sackler Institute of Pulmonary Pharmacology, Institute of Pharmaceutical Science, King's College London, London, United Kingdom (B.M., E.G., C.P.P.); National Institute for Biological Standards and Control, South Mimms, Hertfordshire, United Kingdom (J.H., E.G.) and School of Pharmacy, University College London, London, United Kingdom (R.L.)
| | - Rebeca Lever
- Sackler Institute of Pulmonary Pharmacology, Institute of Pharmaceutical Science, King's College London, London, United Kingdom (B.M., E.G., C.P.P.); National Institute for Biological Standards and Control, South Mimms, Hertfordshire, United Kingdom (J.H., E.G.) and School of Pharmacy, University College London, London, United Kingdom (R.L.)
| | - Elaine Gray
- Sackler Institute of Pulmonary Pharmacology, Institute of Pharmaceutical Science, King's College London, London, United Kingdom (B.M., E.G., C.P.P.); National Institute for Biological Standards and Control, South Mimms, Hertfordshire, United Kingdom (J.H., E.G.) and School of Pharmacy, University College London, London, United Kingdom (R.L.)
| | - Clive P Page
- Sackler Institute of Pulmonary Pharmacology, Institute of Pharmaceutical Science, King's College London, London, United Kingdom (B.M., E.G., C.P.P.); National Institute for Biological Standards and Control, South Mimms, Hertfordshire, United Kingdom (J.H., E.G.) and School of Pharmacy, University College London, London, United Kingdom (R.L.)
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4
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Correnti M, Gammella E, Cairo G, Recalcati S. Iron Mining for Erythropoiesis. Int J Mol Sci 2022; 23:ijms23105341. [PMID: 35628152 PMCID: PMC9140467 DOI: 10.3390/ijms23105341] [Citation(s) in RCA: 2] [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: 04/15/2022] [Revised: 05/05/2022] [Accepted: 05/09/2022] [Indexed: 01/27/2023] Open
Abstract
Iron is necessary for essential processes in every cell of the body, but the erythropoietic compartment is a privileged iron consumer. In fact, as a necessary component of hemoglobin and myoglobin, iron assures oxygen distribution; therefore, a considerable amount of iron is required daily for hemoglobin synthesis and erythroid cell proliferation. Therefore, a tight link exists between iron metabolism and erythropoiesis. The liver-derived hormone hepcidin, which controls iron homeostasis via its interaction with the iron exporter ferroportin, coordinates erythropoietic activity and iron homeostasis. When erythropoiesis is enhanced, iron availability to the erythron is mainly ensured by inhibiting hepcidin expression, thereby increasing ferroportin-mediated iron export from both duodenal absorptive cells and reticuloendothelial cells that process old and/or damaged red blood cells. Erythroferrone, a factor produced and secreted by erythroid precursors in response to erythropoietin, has been identified and characterized as a suppressor of hepcidin synthesis to allow iron mobilization and facilitate erythropoiesis.
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Pereyra D, Heber S, Schrottmaier WC, Santol J, Pirabe A, Schmuckenschlager A, Kammerer K, Ammon D, Sorz T, Fritsch F, Hayden H, Pawelka E, Krüger P, Rumpf B, Traugott MT, Glaser P, Firbas C, Schörgenhofer C, Seitz T, Karolyi M, Pabinger I, Brostjan C, Starlinger P, Weiss G, Bellmann-Weiler R, Salzer HJF, Jilma B, Zoufaly A, Assinger A. Low molecular weight heparin use in COVID-19 is associated with curtailed viral persistence-a retrospective multicenter observational study. Cardiovasc Res 2021; 117:2807-2820. [PMID: 34609480 PMCID: PMC8500043 DOI: 10.1093/cvr/cvab308] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Revised: 05/04/2021] [Indexed: 12/22/2022] Open
Abstract
Aims Anticoagulation was associated with improved survival of hospitalized coronavirus disease 2019 (COVID-19) patients in large-scale studies. Yet, the development of COVID-19-associated coagulopathy (CAC) and the mechanism responsible for improved survival of anticoagulated patients with COVID-19 remain largely elusive. This investigation aimed to explore the effects of anticoagulation and low-molecular-weight heparin (LMWH) in particular on patient outcome, CAC development, thromboinflammation, cell death, and viral persistence. Methods and results Data of 586 hospitalized COVID-19 patients from three different regions of Austria were evaluated retrospectively. Of these, 419 (71.5%) patients received LMWH and 62 (10.5%) received non-vitamin-K oral anticoagulants (NOACs) during hospitalization. Plasma was collected at different time points in a subset of 106 patients in order to evaluate markers of thromboinflammation (H3Cit-DNA) and the cell death marker cell-free DNA (cfDNA). Use of LMWH was associated with improved survival upon multivariable Cox regression (hazard ratio = 0.561, 95% confidence interval: 0.348–0.906). Interestingly, neither LMWH nor NOAC was associated with attenuation of D-dimer increase over time, or thromboinflammation. In contrast, anticoagulation was associated with a decrease in cfDNA during hospitalization, and curtailed viral persistence was observed in patients using LMWH leading to a 4-day reduction of virus positivity upon quantitative polymerase chain reaction [13 (interquartile range: 6–24) vs. 9 (interquartile range: 5–16) days, P = 0.009]. Conclusion Time courses of haemostatic and thromboinflammatory biomarkers were similar in patients with and without LMWH, indicating either no effects of LMWH on haemostasis or that LMWH reduced hypercoagulability to levels of patients without LMWH. Nonetheless, anticoagulation with LMWH was associated with reduced mortality, improved markers of cell death, and curtailed viral persistence, indicating potential beneficial effects of LMWH beyond haemostasis, which encourages use of LMWH in COVID-19 patients without contraindications.
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Affiliation(s)
- David Pereyra
- Department of Vascular Biology and Thrombosis Research, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria.,Department of Surgery, Division of Visceral Surgery, Medical University of Vienna, General Hospital Vienna, Vienna, Austria
| | - Stefan Heber
- Institute of Physiology, Centre of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Waltraud C Schrottmaier
- Department of Vascular Biology and Thrombosis Research, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Jonas Santol
- Department of Surgery, Division of Visceral Surgery, Medical University of Vienna, General Hospital Vienna, Vienna, Austria
| | - Anita Pirabe
- Department of Vascular Biology and Thrombosis Research, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Anna Schmuckenschlager
- Department of Vascular Biology and Thrombosis Research, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Kerstin Kammerer
- Department of Vascular Biology and Thrombosis Research, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Daphni Ammon
- Department of Surgery, Division of Visceral Surgery, Medical University of Vienna, General Hospital Vienna, Vienna, Austria
| | - Thomas Sorz
- Department of Surgery, Division of Visceral Surgery, Medical University of Vienna, General Hospital Vienna, Vienna, Austria
| | - Fabian Fritsch
- Department of Surgery, Division of Visceral Surgery, Medical University of Vienna, General Hospital Vienna, Vienna, Austria
| | - Hubert Hayden
- Department of Surgery, Division of Vascular Surgery, Medical University of Vienna, General Hospital Vienna, Vienna, Austria
| | - Erich Pawelka
- Department of Medicine IV, Kaiser Franz Josef Hospital, Vienna, Austria
| | - Philipp Krüger
- Department of Vascular Biology and Thrombosis Research, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria.,Department of Surgery, Division of Visceral Surgery, Medical University of Vienna, General Hospital Vienna, Vienna, Austria
| | - Benedikt Rumpf
- Department of Surgery, Division of Visceral Surgery, Medical University of Vienna, General Hospital Vienna, Vienna, Austria.,Department of Medicine IV, Kaiser Franz Josef Hospital, Vienna, Austria
| | | | - Pia Glaser
- Department of Medicine I, Medical University of Vienna, General Hospital Vienna, Vienna, Austria
| | - Christa Firbas
- Department of Clinical Pharmacology, Medical University of Vienna, General Hospital Vienna, Vienna, Austria
| | - Christian Schörgenhofer
- Department of Clinical Pharmacology, Medical University of Vienna, General Hospital Vienna, Vienna, Austria
| | - Tamara Seitz
- Department of Medicine IV, Kaiser Franz Josef Hospital, Vienna, Austria
| | - Mario Karolyi
- Department of Medicine IV, Kaiser Franz Josef Hospital, Vienna, Austria
| | - Ingrid Pabinger
- Department of Medicine I, Medical University of Vienna, General Hospital Vienna, Vienna, Austria
| | - Christine Brostjan
- Department of Surgery, Division of Vascular Surgery, Medical University of Vienna, General Hospital Vienna, Vienna, Austria
| | - Patrick Starlinger
- Department of Surgery, Division of Visceral Surgery, Medical University of Vienna, General Hospital Vienna, Vienna, Austria
| | - Günter Weiss
- Department of Internal Medicine II, Medical University of Innsbruck, Innsbruck, Austria
| | - Rosa Bellmann-Weiler
- Department of Internal Medicine II, Medical University of Innsbruck, Innsbruck, Austria
| | - Helmut J F Salzer
- Department of Pulmonology, Kepler University Hospital, and Johannes Kepler University, Linz, Austria
| | - Bernd Jilma
- Department of Clinical Pharmacology, Medical University of Vienna, General Hospital Vienna, Vienna, Austria
| | - Alexander Zoufaly
- Department of Medicine IV, Kaiser Franz Josef Hospital, Vienna, Austria
| | - Alice Assinger
- Department of Vascular Biology and Thrombosis Research, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
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6
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Li L, Wang X, Zhang H, Chen Q, Cui H. Low anticoagulant heparin-iron complex targeting inhibition of hepcidin ameliorates anemia of chronic disease in rodents. Eur J Pharmacol 2021; 897:173958. [PMID: 33610598 DOI: 10.1016/j.ejphar.2021.173958] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Revised: 02/08/2021] [Accepted: 02/15/2021] [Indexed: 11/15/2022]
Abstract
Hepcidin is the only known hormone negatively regulates systemic iron availability, its excess contributes to anemia of chronic disease (ACD).Heparin has been shown to be an efficient hepcidin inhibitor both in vitro and in vivo, but its powerful anticoagulant activity limits this therapeutic application. To this end, heparin-iron complex was prepared by electrostatic interaction and/or coordination between heparin and dihydroxy iron solution ([Fe(OH)2]+) under the condition of ultrasonic assisted. We assessed the anticoagulant activity of heparin-iron in vitro and vivo by sheep plasma, chromogenic substrate method and tail-bleeding in mice, respectively. Anti-hepcidin effect of heparin-iron was detected in HepG2 cell and LPS induced acute inflammation mice by qRT-PCR and ELISA. Turpentine-induced anemia mice were established to evaluate the effect of heparin-iron in ACD. Mice were treated with heparin-iron for 4 weeks. The results indicated that heparin-iron has significantly reduced anticoagulant activity in vitro and in vivo, strongly decreases hepcidin mRNA and IL-6 induced high level of secreted hepcidin in HepG2 cell. Heparin-iron was also found to cause a reduction on hepcidin expression through BMP/SMAD and JAK/STAT3 pathways in LPS induced acute inflammation model in mice. In ACD mice, heparin-iron could lower elevated serum hepcidin and improve anemia. These findings demonstrated low anticoagulant heparin-iron has potential applications for the treatment of ACD with high hepcidin levels.
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Affiliation(s)
- Liuxiang Li
- Key Laboratory of Chemical Biology, Ministry of Education, Institute of Biochemical and Biotechnological Drugs, School of Pharmaceutical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, 250012, Shandong, China
| | - Xiaoxue Wang
- Key Laboratory of Chemical Biology, Ministry of Education, Institute of Biochemical and Biotechnological Drugs, School of Pharmaceutical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, 250012, Shandong, China
| | - Hongyu Zhang
- Key Laboratory of Chemical Biology, Ministry of Education, Institute of Biochemical and Biotechnological Drugs, School of Pharmaceutical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, 250012, Shandong, China
| | - Qingqing Chen
- National Glycoengineering Research Center, Cheeloo College of Medicine, Shandong University, Jinan, 250012, Shandong, China
| | - Huifei Cui
- Key Laboratory of Chemical Biology, Ministry of Education, Institute of Biochemical and Biotechnological Drugs, School of Pharmaceutical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, 250012, Shandong, China; National Glycoengineering Research Center, Cheeloo College of Medicine, Shandong University, Jinan, 250012, Shandong, China; Shandong Provincial Key Laboratory of Carbohydrate Chemistry and Glycobiology, Cheeloo College of Medicine, Shandong University, Jinan, 250012, Shandong, China.
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Banchini F, Vallisa D, Maniscalco P, Capelli P. Iron overload and Hepcidin overexpression could play a key role in COVID infection, and may explain vulnerability in elderly, diabetics, and obese patients. ACTA BIO-MEDICA : ATENEI PARMENSIS 2020; 91:e2020013. [PMID: 32921750 PMCID: PMC7716981 DOI: 10.23750/abm.v91i3.9826] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Accepted: 06/04/2020] [Indexed: 12/24/2022]
Abstract
BACKGROUND The COVID epidemic hit like a tsunami worldwide. At the time of its arrival in Italy, available literary data were meager, and most of them concerned its epidemiology. World Health Organization proposed guidelines in march 2020, a strategy of treatment has been developed, and a significant number of subsequent articles have been published to understand, prevent, and cure COVID patients. METHODS From the observation of two patients, we performed a careful analysis of scientific literature to unearth the relation between COVID infection, clinical manifestations as pneumonia and thrombosis, and to find out why it frequently affects obese, diabetics, and elderly patients. RESULTS The analysis shows that hepcidin could represent one of such correlating factors. Hepcidin is most elevated in older age, in non-insulin diabetics patients and in obese people. It is the final target therapy of many medicaments frequently used. Viral disease, and in particular SARS-CoV19, could induce activation of the hepcidin pathway, which in turn is responsible for an increase in the iron load. Excess of iron can lead to cell death by ferroptosis and release into the bloodstream, such as free iron, which in turn has toxic and pro-coagulative effects. CONCLUSIONS Overexpression of hepcidin and iron overload might play a crucial role in COVID infection, becoming potential targets for treatment. Hepcidin could also be considered as a biomarker to measure the effectiveness of our treatments and the restoration of iron homeostasis the final intent. (www.actabiomedica.it).
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Affiliation(s)
- Filippo Banchini
- Department of General Surgery, Guglielmo da Saliceto Hospital, Piacenza, Italy.
| | - Daniele Vallisa
- Department of Hematology , Guglielmo da Saliceto Hospital, Piacenza, Italy.
| | - Pietro Maniscalco
- Orthopedics and Traumatology Department, Guglielmo da Saliceto Hospital, Piacenza, Italy.
| | - Patrizio Capelli
- Department of General Surgery, Guglielmo da Saliceto Hospital, Piacenza, Italy.
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Ashok A, Chaudhary S, Kritikos AE, Kang MH, McDonald D, Rhee DJ, Singh N. TGFβ2-Hepcidin Feed-Forward Loop in the Trabecular Meshwork Implicates Iron in Glaucomatous Pathology. Invest Ophthalmol Vis Sci 2020; 61:24. [PMID: 32182331 PMCID: PMC7401420 DOI: 10.1167/iovs.61.3.24] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Purpose Elevated levels of transforming-growth-factor (TGF)-β2 in the trabecular meshwork (TM) and aqueous humor are associated with primary open-angle glaucoma (POAG). The underlying mechanism includes alteration of extracellular matrix homeostasis through Smad-dependent and independent signaling. Smad4, an essential co-Smad, upregulates hepcidin, the master regulator of iron homeostasis. Here, we explored whether TGF-β2 upregulates hepcidin, implicating iron in the pathogenesis of POAG. Methods Primary human TM cells and human and bovine ex vivo anterior segment organ cultures were exposed to bioactive TGF-β2, hepcidin, heparin (a hepcidin antagonist), or N-acetyl carnosine (an antioxidant), and the change in the expression of hepcidin, ferroportin, ferritin, and TGF-β2 was evaluated by semiquantitative RT-PCR, Western blotting, and immunohistochemistry. Increase in reactive oxygen species (ROS) was quantified with dihydroethidium, an ROS-sensitive dye. Results Primary human TM cells and bovine TM tissue synthesize hepcidin locally, which is upregulated by bioactive TGF-β2. Hepcidin downregulates ferroportin, its downstream target, increasing ferritin and iron-catalyzed ROS. This causes reciprocal upregulation of TGF-β2 at the transcriptional and translational levels. Heparin downregulates hepcidin, and reduces TGF-β2-mediated increase in ferritin and ROS. Notably, both heparin and N-acetyl carnosine reduce TGF-β2-mediated reciprocal upregulation of TGF-β2. Conclusions The above observations suggest that TGF-β2 and hepcidin form a self-sustained feed-forward loop through iron-catalyzed ROS. This loop is partially disrupted by a hepcidin antagonist and an anti-oxidant, implicating iron and ROS in TGF-β2-mediated POAG. We propose that modification of currently available hepcidin antagonists for ocular use may prove beneficial for the therapeutic management of TGF-β2-associated POAG.
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Billings PC, Bizzaro C, Yang E, Chung J, Mundy C, Pacifici M. Human and mouse activin genes: Divergent expression of activin A protein variants and identification of a novel heparan sulfate-binding domain in activin B. PLoS One 2020; 15:e0229254. [PMID: 32074129 PMCID: PMC7029874 DOI: 10.1371/journal.pone.0229254] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Accepted: 02/03/2020] [Indexed: 11/18/2022] Open
Abstract
Activins are members of the transforming growth factor-β (TGF-β) superfamily of signaling proteins and were originally identified as components of follicular fluid. The proteins are now known to play critical roles in numerous normal and pathological processes and conditions, but less is clear about the relationships between their gene organization and protein variant expression and structure. The four human and mouse activin (Act) genes, termed INHβA, INHβB, INHβC and INHβE, differ in exon numbers. Human INHβA is the most complex with 7 exons and elicits production of three Act A variants (Act A X1, X2 and X3) differing in their pro-region, as we showed previously. Here we further analyzed the mouse INHβA gene and found that its 4 exons encode for a single open reading frame (mouse Act A), corresponding to the shortest human Act A X3 variant. Activins are synthesized and secreted as large complexes made of a long pro-region and a short mature C- terminal ligand and are known to interact with the heparan sulfate (HS) chains of cell surface and matrix proteoglycans. Human Act A X1 and X2 variants do have a HS-binding domain (HBD) with Cardin/Weintraub traits in their pro-region, while the X3 variant does not as shown previously. We found that the mouse Act A lacks a HBD as well. However, we identified a typical HBD in the pro-region of both mouse and human Act B, and synthetic peptides containing that domain interacted with immobilized HS and cell surface with nanomolar affinity. In sum, human and mouse Act A genes elicit expression of different variant sets, while there is concordance in Act B protein expression, reflecting possible evolutionary diversity in function of, and responses to, these signaling proteins in the two species.
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Affiliation(s)
- Paul C. Billings
- Translational Research Program in Pediatric Orthopaedics, Division of Orthopaedic Surgery, The Children’s Hospital of Philadelphia, Philadelphia, PA, United States of America
- * E-mail:
| | - Candice Bizzaro
- Translational Research Program in Pediatric Orthopaedics, Division of Orthopaedic Surgery, The Children’s Hospital of Philadelphia, Philadelphia, PA, United States of America
| | - Evan Yang
- Translational Research Program in Pediatric Orthopaedics, Division of Orthopaedic Surgery, The Children’s Hospital of Philadelphia, Philadelphia, PA, United States of America
| | - Juliet Chung
- Translational Research Program in Pediatric Orthopaedics, Division of Orthopaedic Surgery, The Children’s Hospital of Philadelphia, Philadelphia, PA, United States of America
| | - Christina Mundy
- Translational Research Program in Pediatric Orthopaedics, Division of Orthopaedic Surgery, The Children’s Hospital of Philadelphia, Philadelphia, PA, United States of America
| | - Maurizio Pacifici
- Translational Research Program in Pediatric Orthopaedics, Division of Orthopaedic Surgery, The Children’s Hospital of Philadelphia, Philadelphia, PA, United States of America
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10
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Ashok A, Chaudhary S, McDonald D, Kritikos A, Bhargava D, Singh N. Local synthesis of hepcidin in the anterior segment of the eye: A novel observation with physiological and pathological implications. Exp Eye Res 2020; 190:107890. [PMID: 31811823 PMCID: PMC6931014 DOI: 10.1016/j.exer.2019.107890] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2019] [Revised: 10/27/2019] [Accepted: 12/01/2019] [Indexed: 12/22/2022]
Abstract
PURPOSE The avascular cornea, trabecular meshwork (TM), and lens obtain iron, an essential biometal, from the aqueous humor (AH). The mechanism by which this exchange is regulated, however, is unclear. Recently we reported that non-pigmented ciliary epithelial cells express ferroportin (Fpn) (Ashok, 2018b), an iron export protein modulated by hepcidin, the master regulator of iron homeostasis secreted mainly by the liver. Here, we explored whether ciliary epithelial and other cells in the anterior segment synthesize hepcidin, suggesting local regulation of iron exchange at this site. METHODS Human and bovine eyes were dissected to isolate the ciliary body (CB), corneal endothelial (CE), TM, lens epithelial (LE), and outer epithelial cell layer of the iris. Total mRNA and protein lysates were processed to evaluate the synthesis and expression of hepcidin, the iron regulatory peptide hormone, Fpn, the only known iron export protein, ceruloplasmin (Cp), a ferroxidase necessary for iron export, transferrin receptor (TfR), a major iron uptake protein, and ferritin, a major iron storage protein. A combination of techniques including reverse transcription polymerase chain reaction (RT-PCR) of total mRNA, Western blotting of protein lysates, and immunofluorescence of fixed tissue sections were used to accomplish these goals. RESULTS RT-PCR of isolated tissue samples revealed hepcidin-specific mRNA in the CB, TM, CE, and LE of the bovine eye. Western blotting of protein lysates from these tissues showed reactivity for hepcidin, Fpn, ferritin, and TfR. Western blotting and immunohistochemistry of similar tissues isolated from cadaveric human eyes showed expression of hepcidin, Fpn, and Cp in these samples. Notably, Fpn and Cp were expressed on the basolateral membrane of non-pigmented ciliary epithelial cells, facing the AH. CONCLUSIONS Synthesis and expression of hepcidin and Fpn in the ciliary epithelium suggests local regulation of iron transport from choroidal plexus in the ciliary body to the AH across the blood-aqueous barrier. Expression of hepcidin and Fpn in CE, TM, and LE cells indicates additional regulation of iron exchange between the AH and cornea, TM, and lens, suggesting autonomous regulation of iron homeostasis in the anterior segment. Physiological and pathological implications of these observations are discussed.
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Affiliation(s)
- Ajay Ashok
- Department of Pathology, School of Medicine, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Suman Chaudhary
- Department of Pathology, School of Medicine, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Dallas McDonald
- Department of Pathology, School of Medicine, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Alexander Kritikos
- Department of Pathology, School of Medicine, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Disha Bhargava
- Department of Pathology, School of Medicine, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Neena Singh
- Department of Pathology, School of Medicine, Case Western Reserve University, Cleveland, OH, 44106, USA.
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Abstract
Iron is an essential element that is indispensable for life. The delicate physiological body iron balance is maintained by both systemic and cellular regulatory mechanisms. The iron-regulatory hormone hepcidin assures maintenance of adequate systemic iron levels and is regulated by circulating and stored iron levels, inflammation and erythropoiesis. The kidney has an important role in preventing iron loss from the body by means of reabsorption. Cellular iron levels are dependent on iron import, storage, utilization and export, which are mainly regulated by the iron response element-iron regulatory protein (IRE-IRP) system. In the kidney, iron transport mechanisms independent of the IRE-IRP system have been identified, suggesting additional mechanisms for iron handling in this organ. Yet, knowledge gaps on renal iron handling remain in terms of redundancy in transport mechanisms, the roles of the different tubular segments and related regulatory processes. Disturbances in cellular and systemic iron balance are recognized as causes and consequences of kidney injury. Consequently, iron metabolism has become a focus for novel therapeutic interventions for acute kidney injury and chronic kidney disease, which has fuelled interest in the molecular mechanisms of renal iron handling and renal injury, as well as the complex dynamics between systemic and local cellular iron regulation.
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