1
|
Nunes Rosado FG, Lekovic D, Gagan J, Malter J, Chen W, Sykes DB. Comprehensive Next-Generation Sequencing Testing in a Patient with TEMPI Syndrome. Lab Med 2023; 54:546-549. [PMID: 36864546 DOI: 10.1093/labmed/lmad003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/04/2023] Open
Abstract
TEMPI syndrome is a new and poorly understood disease that is currently considered a type of plasma cell neoplasm with paraneoplastic manifestations. The TEMPI acronym defines the hallmarks of the syndrome: T for telangiectasia; E for erythrocytosis with elevated erythropoietin; M, monoclonal gammopathy; P, perinephric collections; and I, intrapulmonary shunting. Due to the marked erythrocytosis as the most common presenting feature, TEMPI is often misdiagnosed as polycythemia vera. However, unlike polycythemia vera, TEMPI is not associated with a JAK2 mutation. The pathogenesis of TEMPI syndrome is unknown, although a few hypothetical disease mechanisms have been previously discussed. Here we present a new case of TEMPI syndrome, discuss results of a next-generation sequencing (NGS) panel covering 1,425 known cancer-related genes, and review the current literature with focus on an update of the genetics of TEMPI syndrome. This is the first report of TEMPI that includes results of comprehensive NGS testing.
Collapse
Affiliation(s)
| | - Danijela Lekovic
- Clinic of Hematology, University Clinical Center Serbia, Belgrade, Serbia, Medical Faculty, University of Belgrade, Belgrade, Serbia
| | - Jeffrey Gagan
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - James Malter
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Weina Chen
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - David B Sykes
- Department of Internal Medicine, Massachusetts General Hospital, Boston, MA, USA
| |
Collapse
|
2
|
Hudler P, Urbancic M. The Role of VHL in the Development of von Hippel-Lindau Disease and Erythrocytosis. Genes (Basel) 2022; 13:genes13020362. [PMID: 35205407 PMCID: PMC8871608 DOI: 10.3390/genes13020362] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2022] [Revised: 02/14/2022] [Accepted: 02/15/2022] [Indexed: 12/20/2022] Open
Abstract
Von Hippel-Lindau disease (VHL disease or VHL syndrome) is a familial multisystem neoplastic syndrome stemming from germline disease-associated variants of the VHL tumor suppressor gene on chromosome 3. VHL is involved, through the EPO-VHL-HIF signaling axis, in oxygen sensing and adaptive response to hypoxia, as well as in numerous HIF-independent pathways. The diverse roles of VHL confirm its implication in several crucial cellular processes. VHL variations have been associated with the development of VHL disease and erythrocytosis. The association between genotypes and phenotypes still remains ambiguous for the majority of mutations. It appears that there is a distinction between erythrocytosis-causing VHL variations and VHL variations causing VHL disease with tumor development. Understanding the pathogenic effects of VHL variants might better predict the prognosis and optimize management of the patient.
Collapse
Affiliation(s)
- Petra Hudler
- Medical Centre for Molecular Biology, Institute of Biochemistry and Molecular Genetics, Faculty of Medicine, University of Ljubljana, Vrazov trg 2, 1000 Ljubljana, Slovenia;
| | - Mojca Urbancic
- Eye Hospital, University Medical Centre Ljubljana, Grabloviceva ulica 46, 1000 Ljubljana, Slovenia
- Correspondence:
| |
Collapse
|
3
|
McMullin MF. Genetic Background of Congenital Erythrocytosis. Genes (Basel) 2021; 12:genes12081151. [PMID: 34440325 PMCID: PMC8392557 DOI: 10.3390/genes12081151] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Revised: 07/23/2021] [Accepted: 07/26/2021] [Indexed: 01/14/2023] Open
Abstract
True erythrocytosis is present when the red cell mass is greater than 125% of predicted sex and body mass, which is reflected by elevated hemoglobin and hematocrit. Erythrocytosis can be primary or secondary and congenital or acquired. Congenital defects are often found in those diagnosed at a young age and with a family history of erythrocytosis. Primary congenital defects mainly include mutations in the Erythropoietin receptor gene but SH2B3 has also been implicated. Secondary congenital erythrocytosis can arise through a variety of genetic mechanisms, including mutations in the genes in the oxygen sensing pathway, with high oxygen affinity hemoglobin variants and mutations in other genes such as BPMG, where ultimately the production of erythropoietin is increased, resulting in erythrocytosis. Recently, mutations in PIEZ01 have been associated with erythrocytosis. In many cases, a genetic variant cannot be identified, leaving a group of patients with the label idiopathic erythrocytosis who should be the subject of future investigations. The clinical course in congenital erythrocytosis is hard to evaluate as these are rare cases. However, some of these patients may well present at a young age and with sometimes catastrophic thromboembolic events. There is little evidence to guide the management of congenital erythrocytosis but the use of venesection and low dose aspirin should be considered.
Collapse
|
4
|
Concurrent heterozygous Von-Hippel-Lindau and transmembrane-protein-127 gene mutation causing an erythropoietin-secreting pheochromocytoma in a normotensive patient with severe erythrocytosis. J Hypertens 2021; 38:340-346. [PMID: 31568062 DOI: 10.1097/hjh.0000000000002253] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
BACKGROUND Mutations of genes related to Krebs cycle enzymes, kinases or to pseudohypoxic signaling pathways, including Von-Hippel-Lindau (VHL) and transmembrane-protein-127 predispose to pheochromocytoma and paraganglioma development. Homozygous loss of function mutation of VHL (VHL 598C>T) gene can associate with polycythemia because of an altered hypoxia sensing. PATIENT A 19-year-old normotensive man presented with headache, fatigue associated with severe erythrocytosis (hematocrit 76%), high hemoglobin (25.3 g/dl) in normoxic condition. Bone marrow biopsy showed marked hyperplasia of erythroid series. The Janus kinase 2 (V617F) mutation was absent. Abdominal computed tomography scan showed a 8-mm left adrenal pheochromocytoma with tracer uptake on GaDOTA-octreotate PET. Twenty-four-hour urinary metanephrine excretion was slightly increased, while normetanephrine, 3-methoxytyramine were normal. Adrenal veins sampling showed high left-side erythropoietin secretion. RESULTS Next-generation sequencing genetic analysis evidenced two concurrent heterozygous mutation of VHL598C>T and of transmembrane-protein-127 c.268G>A. Left side adrenalectomy improved symptoms, erythrocytosis, hemoglobin, and erythropoietin circulating levels. Adrenal histologic sections showed a pheochromocytoma with extensive immunostaining for erythropoietin, but also coexpression of chromogranin A, a marker of chromaffin tissue. CONCLUSION Congenital polycythemia was clinically diagnosed, mimicking Chuvash polycythemia. Chuvash polycythemia is an autosomal recessive disorder that usually harbors a homozygous mutation of VHL598C>T but not predispose to pheochromocytoma development; in contrast our patient showed for the first time that the concurrent heterozygous VHL and TMEM mutations, resulted in a clinical phenotype of a normotensive patient with polycythemia due to erythropoietin-secreting pheochromocytoma that improved after adrenalectomy.
Collapse
|
5
|
Tremblay D, Yacoub A, Hoffman R. Overview of Myeloproliferative Neoplasms: History, Pathogenesis, Diagnostic Criteria, and Complications. Hematol Oncol Clin North Am 2021; 35:159-176. [PMID: 33641861 PMCID: PMC8669599 DOI: 10.1016/j.hoc.2020.12.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Myeloproliferative disorders are a group of diseases morphologically linked by terminal myeloid cell expansion that frequently evolve from one clinical phenotype to another and eventually progress to acute myeloid leukemia. Diagnostic criteria for the Philadelphia chromosome-negative myeloproliferative neoplasms (MPNs) have been established by the World Health Organization and they are recognized as blood cancers. MPNs have a complex and incompletely understood pathogenesis that includes systemic inflammation, clonal hematopoiesis, and constitutive activation of the JAK-STAT pathway. Complications, such as thrombosis and progression to overt forms of myelofibrosis and acute leukemia, contribute significantly to morbidity and mortality of patients with MPN.
Collapse
Affiliation(s)
- Douglas Tremblay
- Division of Hematology and Medical Oncology, Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
| | - Abdulraheem Yacoub
- Division of Hematologic Malignancies and Cellular Therapeutics, Department of Internal Medicine, The University of Kansas Cancer Center, 2330 Shawnee Mission Parkway, Westwood, KS 66205, USA
| | - Ronald Hoffman
- Division of Hematology and Medical Oncology, Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA.
| |
Collapse
|
6
|
Abstract
Hypoxia can be defined as a relative deficiency in the amount of oxygen reaching the tissues. Hypoxia-inducible factors (HIFs) are critical regulators of the mammalian response to hypoxia. In normal circumstances, HIF-1α protein turnover is rapid, and hyperglycemia further destabilizes the protein. In addition to their role in diabetes pathogenesis, HIFs are implicated in development of the microvascular and macrovascular complications of diabetes. Improving glucose control in people with diabetes increases HIF-1α protein and has wide-ranging benefits, some of which are at least partially mediated by HIF-1α. Nevertheless, most strategies to improve diabetes or its complications via regulation of HIF-1α have not currently proven to be clinically useful. The intersection of HIF biology with diabetes is a complex area in which many further questions remain, especially regarding the well-conducted studies clearly describing discrepant effects of different methods of increasing HIF-1α, even within the same tissues. This Review presents a brief overview of HIFs; discusses the range of evidence implicating HIFs in β cell dysfunction, diabetes pathogenesis, and diabetes complications; and examines the differing outcomes of HIF-targeting approaches in these conditions.
Collapse
Affiliation(s)
- Jenny E Gunton
- Centre for Diabetes, Obesity and Endocrinology, Westmead Institute for Medical Research, Westmead, New South Wales, Australia.,Westmead Hospital, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia.,Garvan Institute of Medical Research, Darlinghurst, New South Wales, Australia
| |
Collapse
|
7
|
Novel mutations in the EPO-R, VHL and EPAS1 genes in the Congenital Erythrocytosis patients. Blood Cells Mol Dis 2020; 85:102479. [DOI: 10.1016/j.bcmd.2020.102479] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2020] [Revised: 07/18/2020] [Accepted: 07/19/2020] [Indexed: 12/11/2022]
|
8
|
Oliveira JL. Algorithmic evaluation of hereditary erythrocytosis: Pathways and caveats. Int J Lab Hematol 2019; 41 Suppl 1:89-94. [PMID: 31069987 DOI: 10.1111/ijlh.13019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2019] [Revised: 02/28/2019] [Accepted: 03/01/2019] [Indexed: 11/28/2022]
Abstract
Multiple algorithms have been published for the evaluation of hereditary erythrocytosis (HE). Typical entry points begin after excluding the more common acquired conditions through investigations of clinical history and assessment of cardiac, pulmonary, or vascular system disorders. Prior exclusion of JAK2 mutations, particularly the common JAK2 V617F mutation, is indicated in adults but less so in pediatric populations. Key decision trees are based on serum erythropoietin levels and p50 results. Recent data reveal some overlap in clinical presentation and laboratory findings in erythrocytosis. Caveats to consider when using algorithmic approaches are discussed.
Collapse
Affiliation(s)
- Jennifer L Oliveira
- Division of Hematopathology, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota
| |
Collapse
|
9
|
Mallik N, Sharma P, Kaur Hira J, Chhabra S, Sreedharanunni S, Kumar N, Naseem S, Sachdeva MUS, Ahluwalia J, Malhotra P, Varma N, Varma S, Das R. Genetic basis of unexplained erythrocytosis in Indian patients. Eur J Haematol 2019; 103:124-130. [PMID: 31132167 DOI: 10.1111/ejh.13267] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Revised: 05/17/2019] [Accepted: 05/20/2019] [Indexed: 01/02/2023]
Abstract
OBJECTIVE To evaluate the spectrum of genetic defects in Indian patients with unexplained erythrocytosis. METHODS Fifteen families (18 patients) with unexplained erythrocytosis were enrolled after excluding polycythemia vera and secondary erythrocytosis. Focused Sanger sequencing from genomic DNA was performed for EPOR (exon 8), VHL (exons 2-3), EGLN1 (exons 2-5), EPAS1 (exon 12), and all exons of HBB, HBA1, and HBA2 genes. RESULTS Eleven of the 18 patients (including two pairs of brothers) had Chuvash polycythemia, that is, homozygosity for VHL:c.598C > T (p.Arg200Trp). Three patients (two of whom were brothers) had HBB mutations associated with increased oxygen-affinity hemoglobin-one had a heterozygous Hb McKees Rocks HBB:c.438T > A (p.Tyr146*), and two brothers showed heterozygous Hb Rainier HBB:c.437A > G (p.Tyr146Cys). No pathogenic variants were found in the remaining four cases. CONCLUSION A gene-by-gene Sanger sequencing approach could determine a genetic basis for erythrocytosis in 11 of the 15 (73%) Indian families, with homozygous VHL:c.598C > T (p.Arg200Trp) being the commonest pathogenic variant. This first study from the Indian subcontinent provides a rationale for analyzing this variant in patients with suspected congenital erythrocytosis from this region. Rare first occurrences of Hb McKees Rocks and Hb Rainier in Indians are also being reported.
Collapse
Affiliation(s)
- Nabhajit Mallik
- Department of Hematology, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | - Prashant Sharma
- Department of Hematology, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | - Jasbir Kaur Hira
- Department of Hematology, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | - Sanjeev Chhabra
- Department of Hematology, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | - Sreejesh Sreedharanunni
- Department of Hematology, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | - Narender Kumar
- Department of Hematology, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | - Shano Naseem
- Department of Hematology, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | - Man Updesh Singh Sachdeva
- Department of Hematology, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | - Jasmina Ahluwalia
- Department of Hematology, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | - Pankaj Malhotra
- Department of Internal Medicine, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | - Neelam Varma
- Department of Hematology, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | - Subhash Varma
- Department of Internal Medicine, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | - Reena Das
- Department of Hematology, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| |
Collapse
|
10
|
Rumi E, Cazzola M. Advances in understanding the pathogenesis of familial myeloproliferative neoplasms. Br J Haematol 2017; 178:689-698. [PMID: 28444727 DOI: 10.1111/bjh.14713] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Myeloproliferative neoplasms (MPNs) are generally acquired as a result of a somatic stem cell mutation leading to clonal expansion of myeloid precursors. In addition to sporadic cases, familial MPN occurs when one or several MPN affect different relatives of the same family. MPN driver mutations (JAK2, CALR, MPL) are somatically acquired also in familial cases, so a genetic predisposition to acquire one of the MPN driver mutations would be inherited, even though the causative germline mutations underlying familial MPN remain largely unknown. Recently some germline variants [ATG2B and GSKIP duplication, RBBP6 mutations, SH2B3 (LNK) mutations], which can cause familial MPN, have been reported but these mutations are rare and do not explain most familial cases. Patients with familial MPN show the same clinical features and suffer the same complications as those with sporadic disease. This review aims to offer up-to-date information regarding the genetics of familial MPN.
Collapse
Affiliation(s)
- Elisa Rumi
- Department of Haematology Oncology, Fondazione IRCCS Policlinico S. Matteo, Pavia, Italy.,Department of Molecular Medicine, University of Pavia, Pavia, Italy
| | - Mario Cazzola
- Department of Haematology Oncology, Fondazione IRCCS Policlinico S. Matteo, Pavia, Italy.,Department of Molecular Medicine, University of Pavia, Pavia, Italy
| |
Collapse
|
11
|
Camps C, Petousi N, Bento C, Cario H, Copley RR, McMullin MF, van Wijk R, Ratcliffe PJ, Robbins PA, Taylor JC. Gene panel sequencing improves the diagnostic work-up of patients with idiopathic erythrocytosis and identifies new mutations. Haematologica 2016; 101:1306-1318. [PMID: 27651169 PMCID: PMC5394871 DOI: 10.3324/haematol.2016.144063] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Accepted: 07/26/2016] [Indexed: 12/31/2022] Open
Abstract
Erythrocytosis is a rare disorder characterized by increased red cell mass and elevated hemoglobin concentration and hematocrit. Several genetic variants have been identified as causes for erythrocytosis in genes belonging to different pathways including oxygen sensing, erythropoiesis and oxygen transport. However, despite clinical investigation and screening for these mutations, the cause of disease cannot be found in a considerable number of patients, who are classified as having idiopathic erythrocytosis. In this study, we developed a targeted next-generation sequencing panel encompassing the exonic regions of 21 genes from relevant pathways (~79 Kb) and sequenced 125 patients with idiopathic erythrocytosis. The panel effectively screened 97% of coding regions of these genes, with an average coverage of 450×. It identified 51 different rare variants, all leading to alterations of protein sequence, with 57 out of 125 cases (45.6%) having at least one of these variants. Ten of these were known erythrocytosis-causing variants, which had been missed following existing diagnostic algorithms. Twenty-two were novel variants in erythrocytosis-associated genes (EGLN1, EPAS1, VHL, BPGM, JAK2, SH2B3) and in novel genes included in the panel (e.g. EPO, EGLN2, HIF3A, OS9), some with a high likelihood of functionality, for which future segregation, functional and replication studies will be useful to provide further evidence for causality. The rest were classified as polymorphisms. Overall, these results demonstrate the benefits of using a gene panel rather than existing methods in which focused genetic screening is performed depending on biochemical measurements: the gene panel improves diagnostic accuracy and provides the opportunity for discovery of novel variants.
Collapse
Affiliation(s)
- Carme Camps
- National Institute for Health Research (NIHR) Comprehensive Biomedical Research Centre, Oxford, UK
- Wellcome Trust Centre for Human Genetics, University of Oxford, UK
| | - Nayia Petousi
- Nuffield Department of Medicine, University of Oxford, UK
| | - Celeste Bento
- Hematology Department, Centro Hospitalar e Universitário de Coimbra, Portugal
| | - Holger Cario
- Department of Pediatrics and Adolescent Medicine, University Medical Center, Ulm, Germany
| | - Richard R Copley
- National Institute for Health Research (NIHR) Comprehensive Biomedical Research Centre, Oxford, UK
- Wellcome Trust Centre for Human Genetics, University of Oxford, UK
| | | | | | | | - Peter A Robbins
- Department of Physiology, Anatomy and Genetics, University of Oxford, UK
| | - Jenny C Taylor
- National Institute for Health Research (NIHR) Comprehensive Biomedical Research Centre, Oxford, UK
- Wellcome Trust Centre for Human Genetics, University of Oxford, UK
| |
Collapse
|
12
|
Slingo M, Cole M, Carr C, Curtis MK, Dodd M, Giles L, Heather LC, Tyler D, Clarke K, Robbins PA. The von Hippel-Lindau Chuvash mutation in mice alters cardiac substrate and high-energy phosphate metabolism. Am J Physiol Heart Circ Physiol 2016; 311:H759-67. [PMID: 27422990 PMCID: PMC5142182 DOI: 10.1152/ajpheart.00912.2015] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Accepted: 07/12/2016] [Indexed: 02/07/2023]
Abstract
This is the first integrative metabolic and functional study of the effects of modest hypoxia-inducible factor manipulation within the heart. Of particular note, the combination (and correlation) of perfused heart metabolic flux measurements with the new technique of real-time in vivo magnetic resonance spectroscopy using hyperpolarized pyruvate is a novel development. Hypoxia-inducible factor (HIF) appears to function as a global master regulator of cellular and systemic responses to hypoxia. HIF pathway manipulation is of therapeutic interest; however, global systemic upregulation of HIF may have as yet unknown effects on multiple processes. We used a mouse model of Chuvash polycythemia (CP), a rare genetic disorder that modestly increases expression of HIF target genes in normoxia, to understand what these effects might be within the heart. An integrated in and ex vivo approach was employed. Compared with wild-type controls, CP mice had evidence (using in vivo magnetic resonance imaging) of pulmonary hypertension, right ventricular hypertrophy, and increased left ventricular ejection fraction. Glycolytic flux (measured using [3H]glucose) in the isolated contracting perfused CP heart was 1.8-fold higher. Net lactate efflux was 1.5-fold higher. Furthermore, in vivo 13C-magnetic resonance spectroscopy (MRS) of hyperpolarized [13C1]pyruvate revealed a twofold increase in real-time flux through lactate dehydrogenase in the CP hearts and a 1.6-fold increase through pyruvate dehydrogenase. 31P-MRS of perfused CP hearts under increased workload (isoproterenol infusion) demonstrated increased depletion of phosphocreatine relative to ATP. Intriguingly, no changes in cardiac gene expression were detected. In summary, a modest systemic dysregulation of the HIF pathway resulted in clear alterations in cardiac metabolism and energetics. However, in contrast to studies generating high HIF levels within the heart, the CP mice showed neither the predicted changes in gene expression nor any degree of LV impairment. We conclude that the effects of manipulating HIF on the heart are dose dependent.
Collapse
Affiliation(s)
- Mary Slingo
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford, United Kingdom
| | - Mark Cole
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford, United Kingdom
| | - Carolyn Carr
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford, United Kingdom
| | - Mary K Curtis
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford, United Kingdom
| | - Michael Dodd
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford, United Kingdom
| | - Lucia Giles
- 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
| | - Damian Tyler
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford, United Kingdom
| | - Kieran Clarke
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford, United Kingdom
| | - Peter A Robbins
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford, United Kingdom
| |
Collapse
|
13
|
Affiliation(s)
- M. F. McMullin
- Department of Haematology; Belfast City Hospital; Queen's University Belfast; Belfast UK
| |
Collapse
|
14
|
Hong WJ, Gotlib J. Hereditary erythrocytosis, thrombocytosis and neutrophilia. Best Pract Res Clin Haematol 2014; 27:95-106. [DOI: 10.1016/j.beha.2014.07.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2014] [Accepted: 07/11/2014] [Indexed: 10/25/2022]
|
15
|
Bento C, Percy MJ, Gardie B, Maia TM, van Wijk R, Perrotta S, Della Ragione F, Almeida H, Rossi C, Girodon F, Aström M, Neumann D, Schnittger S, Landin B, Minkov M, Randi ML, Richard S, Casadevall N, Vainchenker W, Rives S, Hermouet S, Ribeiro ML, McMullin MF, Cario H, Chauveau A, Gimenez-Roqueplo AP, Bressac-de-Paillerets B, Altindirek D, Lorenzo F, Lambert F, Dan H, Gad-Lapiteau S, Catarina Oliveira A, Rossi C, Fraga C, Taradin G, Martin-Nuñez G, Vitória H, Diaz Aguado H, Palmblad J, Vidán J, Relvas L, Ribeiro ML, Luigi Larocca M, Luigia Randi M, Pedro Silveira M, Percy M, Gross M, Marques da Costa R, Beshara S, Ben-Ami T, Ugo V. Genetic basis of congenital erythrocytosis: mutation update and online databases. Hum Mutat 2013; 35:15-26. [PMID: 24115288 DOI: 10.1002/humu.22448] [Citation(s) in RCA: 90] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2013] [Accepted: 09/13/2013] [Indexed: 12/15/2022]
Abstract
Congenital erythrocytosis (CE), or congenital polycythemia, represents a rare and heterogeneous clinical entity. It is caused by deregulated red blood cell production where erythrocyte overproduction results in elevated hemoglobin and hematocrit levels. Primary congenital familial erythrocytosis is associated with low erythropoietin (Epo) levels and results from mutations in the Epo receptor gene (EPOR). Secondary CE arises from conditions causing tissue hypoxia and results in increased Epo production. These include hemoglobin variants with increased affinity for oxygen (HBB, HBA mutations), decreased production of 2,3-bisphosphoglycerate due to BPGM mutations, or mutations in the genes involved in the hypoxia sensing pathway (VHL, EPAS1, and EGLN1). Depending on the affected gene, CE can be inherited either in an autosomal dominant or recessive mode, with sporadic cases arising de novo. Despite recent important discoveries in the molecular pathogenesis of CE, the molecular causes remain to be identified in about 70% of the patients. With the objective of collecting all the published and unpublished cases of CE the COST action MPN&MPNr-Euronet developed a comprehensive Internet-based database focusing on the registration of clinical history, hematological, biochemical, and molecular data (http://www.erythrocytosis.org/). In addition, unreported mutations are also curated in the corresponding Leiden Open Variation Database.
Collapse
Affiliation(s)
- Celeste Bento
- Department of Hematology, Centro Hospitalar e Universitário de Coimbra, Coimbra, Portugal
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
16
|
Perrotta S, Stiehl DP, Punzo F, Scianguetta S, Borriello A, Bencivenga D, Casale M, Nobili B, Fasoli S, Balduzzi A, Cro L, Nytko KJ, Wenger RH, Della Ragione F. Congenital erythrocytosis associated with gain-of-function HIF2A gene mutations and erythropoietin levels in the normal range. Haematologica 2013; 98:1624-32. [PMID: 23716564 PMCID: PMC3789469 DOI: 10.3324/haematol.2013.088369] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2013] [Accepted: 05/27/2013] [Indexed: 12/20/2022] Open
Abstract
Hypoxia-inducible factor 2α (HIF-2α) plays a pivotal role in the balancing of oxygen requirements throughout the body. The protein is a transcription factor that modulates the expression of a wide array of genes and, in turn, controls several key processes including energy metabolism, erythropoiesis and angiogenesis. We describe here the identification of two cases of familial erythrocytosis associated with heterozygous HIF2A missense mutations, namely Ile533Val and Gly537Arg. Ile533Val is a novel mutation and represents the genetic HIF2A change nearest to Pro-531, the primary hydroxyl acceptor residue, so far identified. The Gly537Arg missense mutation has already been described in familial erythrocytosis. However, our patient is the only described case of a de novo HIF2A mutation associated with the development of congenital polycythemia. Functional in vivo studies, based on exogenous expression of hybrid HIF-2α transcription factors, indicated that these genetic alterations lead to the stabilization of HIF-2α protein. All the identified polycythemic subjects with HIF2A mutations show serum erythropoietin in the normal range, independently of the hematocrit values and phlebotomy frequency. The erythroid precursors obtained from the peripheral blood of patients showed an altered phenotype, including an increased rate of growth and a modified expression of some HIF-2α target genes. These results suggest the novel proposal that polycythemia observed in subjects with HIF2A mutations might also be due to primary changes in hematopoietic cells and not only secondary to increased erythropoietin levels.
Collapse
Affiliation(s)
- Silverio Perrotta
- Dipartimento della Donna, del Bambino e di Chirurgia Generale e Specialistica, Second University of Naples, Naples, Italy
| | - Daniel P. Stiehl
- Institute of Physiology and Zürich Center for Human Physiology (ZIHP), University of Zürich, Zürich, Switzerland
| | - Francesca Punzo
- Dipartimento della Donna, del Bambino e di Chirurgia Generale e Specialistica, Second University of Naples, Naples, Italy
| | - Saverio Scianguetta
- Dipartimento della Donna, del Bambino e di Chirurgia Generale e Specialistica, Second University of Naples, Naples, Italy
| | - Adriana Borriello
- Department of Biochemistry, Biophysics and General Pathology, Second University of Naples, Naples, Italy
| | - Debora Bencivenga
- Department of Biochemistry, Biophysics and General Pathology, Second University of Naples, Naples, Italy
| | - Maddalena Casale
- Dipartimento della Donna, del Bambino e di Chirurgia Generale e Specialistica, Second University of Naples, Naples, Italy
| | - Bruno Nobili
- Dipartimento della Donna, del Bambino e di Chirurgia Generale e Specialistica, Second University of Naples, Naples, Italy
| | | | - Adriana Balduzzi
- Clinica Pediatrica, Ospedale San Gerardo, Università degli Studi di Milano Bicocca, Monza, Italy
| | - Lilla Cro
- UO Ematologia/CTMO, Fondazione IRCCS Cà Granda, Ospedale Maggiore, Policlinico, Milano, Italy
| | - Katarzyna J. Nytko
- Institute of Physiology and Zürich Center for Human Physiology (ZIHP), University of Zürich, Zürich, Switzerland
| | - Roland H. Wenger
- Institute of Physiology and Zürich Center for Human Physiology (ZIHP), University of Zürich, Zürich, Switzerland
| | - Fulvio Della Ragione
- Department of Biochemistry, Biophysics and General Pathology, Second University of Naples, Naples, Italy
| |
Collapse
|
17
|
Abstract
The idiopathic erythrocytosis (IE) group of disorders is defined by an absolute increase in red cell mass and hematocrit without elevation of the megakaryocytic or granulocytic lineages. It is associated with a wide range of serum erythropoietin (Epo) levels and broadly falls into groups of raised/inappropriately normal or low/undetectable Epo levels. A spectrum of molecular defects has been described in association with IE, which reflects the heterogeneity of this disorder. To date the most common identified cause of IE has been mutations in the von Hippel Landau (VHL) protein, which results in aberrant oxygen sensing and dysregulated Epo production. Studying the molecular basis of IE will provide insights into the control of Epo synthesis and Epo-induced signaling pathways.
Collapse
Affiliation(s)
- M J Percy
- Department of Haematology, Belfast City Hospital, Floor C, Lisburn Road, Belfast, Northern Ireland, UK
| |
Collapse
|
18
|
Abstract
A classic physiologic response to systemic hypoxia is the increase in red blood cell production. Hypoxia-inducible factors (HIFs) orchestrate this response by inducing cell-type specific gene expression changes that result in increased erythropoietin (EPO) production in kidney and liver, in enhanced iron uptake and utilization and in adjustments of the bone marrow microenvironment that facilitate erythroid progenitor maturation and proliferation. In particular HIF-2 has emerged as the transcription factor that regulates EPO synthesis in the kidney and liver and plays a critical role in the regulation of intestinal iron uptake. Its key function in the hypoxic regulation of erythropoiesis is underscored by genetic studies in human populations that live at high-altitude and by mutational analysis of patients with familial erythrocytosis. This review provides a perspective on recent insights into HIF-controlled erythropoiesis and iron metabolism, and examines cell types that have EPO-producing capability. Furthermore, the review summarizes clinical syndromes associated with mutations in the O(2)-sensing pathway and the genetic changes that occur in high altitude natives. The therapeutic potential of pharmacologic HIF activation for the treatment of anemia is discussed.
Collapse
Affiliation(s)
- Volker H Haase
- Department of Medicine, Vanderbilt School of Medicine, Nashville, TN, USA.
| |
Collapse
|
19
|
|
20
|
Kremyanskaya M, Mascarenhas J, Hoffman R. Why Does My Patient Have Erythrocytosis? Hematol Oncol Clin North Am 2012; 26:267-83, vii-viii. [DOI: 10.1016/j.hoc.2012.02.011] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
|
21
|
Chuvash polycythemia VHLR200W mutation is associated with down-regulation of hepcidin expression. Blood 2011; 118:5278-82. [PMID: 21876117 DOI: 10.1182/blood-2011-03-345512] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Hypoxia is known to reduce the expression of hepcidin, the master regulator of iron metabolism. However, it is not clear whether this response is primarily related to increased erythropoiesis driven by hypoxically stimulated erythropoietin or to a more direct effect of hypoxia on hepcidin expression. The germline loss-of-function VHL(R200W) mutation is common in Chuvashia, Russia, and also occurs elsewhere. VHL(R200W) homozygotes have elevated hypoxia-inducible factor 1α (HIF-1α) and HIF-2α levels, increased red cell mass, propensity to thrombosis, and early mortality. Ninety VHL(R200W) homozygotes and 52 controls with normal VHL alleles from Chuvashia, Russia, were studied under basal circumstances. In univariate analyses, serum hepcidin concentration was correlated positively with serum ferritin concentration and negatively with homozygosity for VHL(R200W). After adjustment for serum erythropoietin and ferritin concentrations by multiple linear regression, the geometric mean (95% confidence interval of mean) hepcidin concentration was 8.1 (6.3-10.5) ng/mL in VHL(R200W) homozygotes versus 26.9 (18.6-38.0) ng/mL in controls (P < .001). In contrast, a significant independent relationship of serum erythropoietin, hemoglobin, or RBC count with hepcidin was not observed. In conclusion, up-regulation of the hypoxic response leads to decreased expression of hepcidin that may be independent of increased erythropoietin levels and increased RBC counts.
Collapse
|
22
|
Miasnikova GY, Sergueeva AI, Nouraie M, Niu X, Okhotin DJ, Polyakova LA, Ganz T, Prchal JT, Gordeuk VR. The heterozygote advantage of the Chuvash polycythemia VHLR200W mutation may be protection against anemia. Haematologica 2011; 96:1371-4. [PMID: 21606165 DOI: 10.3324/haematol.2011.045609] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
The germ-line loss-of-function VHL(R200W) mutation is common in Chuvashia, Russia and occurs in other parts of the world. VHL(R200W) homozygotes have elevated hypoxia inducible factor (HIF)-1 and HIF-2 levels, increased hemoglobin concentration, propensity to thrombosis and early mortality. Because the mutation persists from an ancient origin, we hypothesized that there is a heterozygote advantage. Thirty-four VHL(R200W) heterozygotes and 44 controls over 35 years of age from Chuvashia, Russia were studied. Anemia was defined as hemoglobin less than 130 g/L in men and less than 120 g/L in women. Mild anemia was present in 15% of VHL(R200W) heterozygotes and 34% of controls without a mutated VHL allele. By multivariate logistic regression, the odds of anemia were reduced an estimated 5.6-fold in the VHL(R200W) heterozygotes compared to controls (95% confidence interval 1.4-22.7; P=0.017). In conclusion, heterozygosity for VHL(R200W) may provide protection from anemia; such protection could explain the persistence of this mutation.
Collapse
|
23
|
Lee FS, Percy MJ. The HIF pathway and erythrocytosis. ANNUAL REVIEW OF PATHOLOGY-MECHANISMS OF DISEASE 2011; 6:165-92. [PMID: 20939709 DOI: 10.1146/annurev-pathol-011110-130321] [Citation(s) in RCA: 132] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Because of the central role that red blood cells play in the delivery of oxygen to tissues of the body, red blood cell mass must be controlled at precise levels. The glycoprotein hormone erythropoietin (EPO) regulates red blood cell mass. EPO transcription, in turn, is regulated by a distinctive oxygen-sensing mechanism. In this pathway, prolyl hydroxylase domain protein (PHD) site-specifically hydroxylates the α-subunit of the transcription factor hypoxia-inducible factor α (HIF-α), thereby targeting the latter for degradation by the von Hippel-Lindau tumor-suppressor protein (VHL). Under hypoxic conditions, this posttranslational modification of HIF-α is inhibited, which stabilizes it and promotes the transcriptional activation of genes, including that for EPO. Rare patients with erythrocytosis have mutations in the genes encoding for PHD2, HIF-2α, and VHL, which implicates these proteins as critical to the proper control of red blood cell mass in humans.
Collapse
Affiliation(s)
- Frank S Lee
- Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia, 19104, USA.
| | | |
Collapse
|
24
|
Abstract
Erythrocytosis is present when there is an increase in the red cell mass, usually accompanied by an elevated hemoglobin and hematocrit. This occurs when there is an intrinsic defect in the erythroid component of the bone marrow or for secondary reasons when an increase in erythropoietin production drives red cell production. In normoxic conditions, HIF-α interacts with the other proteins in the HIF pathway and is destroyed, but in hypoxic conditions, HIF-α binds to HIF-β and alters the expression of downstream genes, including the erythropoietin gene. The end result is an increase in erythropoietin production. Mutations in any of the genes in the HIF pathway could lead to changed proteins, abnormalities in the degradation of HIF-α and, ultimately, result in increased erythropoietin levels. A number of mutations in the VHL, PHD2, and HIF2A genes have been identified in individuals. These mutations lead to erythrocytosis. The clinical results of these mutations may include some major thromboembolic events in young patients.
Collapse
Affiliation(s)
- Mary Frances McMullin
- Department of Haematology, Belfast City Hospital, Queen's University Belfast, Northern Ireland, UK.
| |
Collapse
|
25
|
Abstract
Our understanding of organismal responses to hypoxia has stemmed from studies of erythropoietin regulation by hypoxia that led to the discovery of the master regulator of the hypoxic response, i.e., hypoxia-inducible factor (HIF). This is a transcription factor that is now known to induce the expression of a battery of genes in response to hypoxia. HIF-1 and HIF-2 regulate many genes that are involved in erythropoiesis and iron metabolism, which are essential for tissue oxygen delivery.
Collapse
Affiliation(s)
- Donghoon Yoon
- Hematology Division, University of Utah, 30 North 1900 East, Salt Lake City, UT 84132, USA
| | | | | |
Collapse
|
26
|
Abstract
The hypoxia-inducible factor (HIF) family of transcription factors directs a coordinated cellular response to hypoxia that includes the transcriptional regulation of a number of metabolic enzymes. Chuvash polycythemia (CP) is an autosomal recessive human disorder in which the regulatory degradation of HIF is impaired, resulting in elevated levels of HIF at normal oxygen tensions. Apart from the polycythemia, CP patients have marked abnormalities of cardiopulmonary function. No studies of integrated metabolic function have been reported. Here we describe the response of these patients to a series of metabolic stresses: exercise of a large muscle mass on a cycle ergometer, exercise of a small muscle mass (calf muscle) which allowed noninvasive in vivo assessments of muscle metabolism using (31)P magnetic resonance spectroscopy, and a standard meal tolerance test. During exercise, CP patients had early and marked phosphocreatine depletion and acidosis in skeletal muscle, greater accumulation of lactate in blood, and reduced maximum exercise capacities. Muscle biopsy specimens from CP patients showed elevated levels of transcript for pyruvate dehydrogenase kinase, phosphofructokinase, and muscle pyruvate kinase. In cell culture, a range of experimental manipulations have been used to study the effects of HIF on cellular metabolism. However, these approaches provide no potential to investigate integrated responses at the level of the whole organism. Although CP is relatively subtle disorder, our study now reveals a striking regulatory role for HIF on metabolism during exercise in humans. These findings have significant implications for the development of therapeutic approaches targeting the HIF pathway.
Collapse
|
27
|
Abstract
The kidney is a highly sensitive oxygen sensor and plays a central role in mediating the hypoxic induction of red blood cell production. Efforts to understand the molecular basis of oxygen-regulated erythropoiesis have led to the identification of erythropoietin (EPO), which is essential for normal erythropoiesis and to the purification of hypoxia-inducible factor (HIF), the transcription factor that regulates EPO synthesis and mediates cellular adaptation to hypoxia. Recent insights into the molecular mechanisms that control and integrate cellular and systemic erythropoiesis-promoting hypoxia responses and their potential as a therapeutic target for the treatment of renal anemia are discussed in this review.
Collapse
Affiliation(s)
- Volker H Haase
- Department of Medicine, Vanderbilt School of Medicine, Nashville, Tennessee 37232, USA.
| |
Collapse
|
28
|
Hickey MM, Richardson T, Wang T, Mosqueira M, Arguiri E, Yu H, Yu QC, Solomides CC, Morrisey EE, Khurana TS, Christofidou-Solomidou M, Simon MC. The von Hippel-Lindau Chuvash mutation promotes pulmonary hypertension and fibrosis in mice. J Clin Invest 2010; 120:827-39. [PMID: 20197624 DOI: 10.1172/jci36362] [Citation(s) in RCA: 115] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2009] [Accepted: 12/14/2009] [Indexed: 12/22/2022] Open
Abstract
Mutation of the von Hippel-Lindau (VHL) tumor suppressor protein at codon 200 (R200W) is associated with a disease known as Chuvash polycythemia. In addition to polycythemia, Chuvash patients have pulmonary hypertension and increased respiratory rates, although the pathophysiological basis of these symptoms is unclear. Here we sought to address this issue by studying mice homozygous for the R200W Vhl mutation (VhlR/R mice) as a model for Chuvash disease. These mice developed pulmonary hypertension independently of polycythemia and enhanced normoxic respiration similar to Chuvash patients, further validating VhlR/R mice as a model for Chuvash disease. Lungs from VhlR/R mice exhibited pulmonary vascular remodeling, hemorrhage, edema, and macrophage infiltration, and lungs from older mice also exhibited fibrosis. HIF-2alpha activity was increased in lungs from VhlR/R mice, and heterozygosity for Hif2a, but not Hif1a, genetically suppressed both the polycythemia and pulmonary hypertension in the VhlR/R mice. Furthermore, Hif2a heterozygosity resulted in partial protection against vascular remodeling, hemorrhage, and edema, but not inflammation, in VhlR/R lungs, suggesting a selective role for HIF-2alpha in the pulmonary pathology and thereby providing insight into the mechanisms underlying pulmonary hypertension. These findings strongly support a dependency of the Chuvash phenotype on HIF-2alpha and suggest potential treatments for Chuvash patients.
Collapse
Affiliation(s)
- Michele M Hickey
- Abramson Family Cancer Research Institute, University of Pennsylvania School of Medicine, Philadelphia, 19104, USA
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
29
|
Percy MJ, Butt NN, Crotty GM, Drummond MW, Harrison C, Jones GL, Turner M, Wallis J, McMullin MF. Identification of high oxygen affinity hemoglobin variants in the investigation of patients with erythrocytosis. Haematologica 2009; 94:1321-2. [PMID: 19734427 DOI: 10.3324/haematol.2009.008037] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
|
30
|
Furlow PW, Percy MJ, Sutherland S, Bierl C, McMullin MF, Master SR, Lappin TRJ, Lee FS. Erythrocytosis-associated HIF-2alpha mutations demonstrate a critical role for residues C-terminal to the hydroxylacceptor proline. J Biol Chem 2009; 284:9050-8. [PMID: 19208626 PMCID: PMC2666553 DOI: 10.1074/jbc.m808737200] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2008] [Revised: 02/03/2009] [Indexed: 01/23/2023] Open
Abstract
A classic physiologic response to hypoxia in humans is the up-regulation of the ERYTHROPOIETIN (EPO) gene, which is the central regulator of red blood cell mass. The EPO gene, in turn, is activated by hypoxia inducible factor (HIF). HIF is a transcription factor consisting of an alpha subunit (HIF-alpha) and a beta subunit (HIF-beta). Under normoxic conditions, prolyl hydroxylase domain protein (PHD, also known as HIF prolyl hydroxylase and egg laying-defective nine protein) site specifically hydroxylates HIF-alpha in a conserved LXXLAP motif (where underlining indicates the hydroxylacceptor proline). This provides a recognition motif for the von Hippel Lindau protein, a component of an E3 ubiquitin ligase complex that targets hydroxylated HIF-alpha for degradation. Under hypoxic conditions, this inherently oxygen-dependent modification is arrested, thereby stabilizing HIF-alpha and allowing it to activate the EPO gene. We previously identified and characterized an erythrocytosis-associated HIF2A mutation, G537W. More recently, we reported two additional erythrocytosis-associated HIF2A mutations, G537R and M535V. Here, we describe the functional characterization of these two mutants as well as a third novel erythrocytosis-associated mutation, P534L. These mutations affect residues C-terminal to the LXXLAP motif. We find that all result in impaired degradation and thus aberrant stabilization of HIF-2alpha. However, each exhibits a distinct profile with respect to their effects on PHD2 binding and von Hippel Lindau interaction. These findings reinforce the importance of HIF-2alpha in human EPO regulation, demonstrate heterogeneity of functional defects arising from these mutations, and point to a critical role for residues C-terminal to the LXXLAP motif in HIF-alpha.
Collapse
Affiliation(s)
- Paul W Furlow
- Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA
| | | | | | | | | | | | | | | |
Collapse
|
31
|
Abstract
The approach to a patient with erythrocytosis is greatly simplified by assessing the clonality of the process upfront. In this regard, there has been a dramatic shift toward genetic testing and away from traditional tests, such as measurement of red cell mass. Clonal erythrocytosis is the diagnostic feature of polycythemia vera (PV) and is almost always associated with a JAK2 mutation (JAK2V617F or exon 12). All other scenarios represent non-clonal erythrocytosis, often referred to as secondary erythrocytosis. Serum erythropoietin (Epo) level is usually normal or elevated in secondary erythrocytosis and subnormal in PV. Therefore, in a patient with acquired erythrocytosis, it is reasonable to begin the diagnostic work-up with peripheral blood JAK2 mutation analysis and serum Epo measurement to distinguish PV from secondary erythrocytosis. Conversely, the patient with life-long erythrocytosis is more likely to suffer from congenital polycythemia and should therefore be evaluated for germline mutations that result in enhanced Epo effect (for example, Epo receptor mutations), altered intracellular oxygen sensing (for example, mutations involving the von Hippel-Lindau tumor suppressor gene) or decreased P50 (for example, high-oxygen-affinity hemoglobinopathy). The order of tests in this instance depends on the clinical scenario and serum Epo level.
Collapse
|
32
|
Percy MJ, Rumi E. Genetic origins and clinical phenotype of familial and acquired erythrocytosis and thrombocytosis. Am J Hematol 2009; 84:46-54. [PMID: 19006225 DOI: 10.1002/ajh.21313] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Familial and acquired erythrocytosis and thrombocytosis are characterized by myeloid lineage hyperproliferation, which is either single or multi-lineage in origin. The single lineage disorders exhibit Mendelian inheritance with polyclonal hematopoiesis and often arise from a single genetic defect. In contrast, the multi-lineage disorders exhibit complex patterns of inheritance with multi-genetic origins and clonal hematopoiesis. They have the potential to acquire JAK2 somatic mutations, but this is not the primary event. Identification of the disease-causing genes will enable better classification of familial and acquired erythrocytosis and thrombocytosis. Furthermore, it will provide an insight into the mechanisms regulating myeloid cell proliferation.
Collapse
Affiliation(s)
- Melanie J Percy
- Department of Haematology, Belfast City Hospital, Belfast, Northern Ireland, UK.
| | | |
Collapse
|
33
|
McMullin MF. Idiopathic erythrocytosis: a disappearing entity. HEMATOLOGY. AMERICAN SOCIETY OF HEMATOLOGY. EDUCATION PROGRAM 2009; 2009:629-635. [PMID: 20008248 DOI: 10.1182/asheducation-2009.1.629] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Erythrocytosis results when there is an increased red cell mass and thus an increased hemoglobin. The causes can be divided into primary intrinsic defects of the erythroid progenitor cell and secondary defects, where factors external to the erythroid compartment are responsible. Both can then be further divided into congenital and acquired categories. Congenital causes include mutations of the erythropoietin receptor and defects of the oxygen-sensing pathway including VHL, PHD2 and HIF2A mutations. When fully investigated there remain a number of patients in whom no cause can be elucidated who are currently described as having idiopathic erythrocytosis. Investigation should start with a full history and examination. Having eliminated the common entity polycythemia vera, further direction for investigation is guided by the erythropoietin level. Clinical consequences of the various erythrocytoses are not clear, but in some groups thromboembolic events have been described in young patients. Evidence is lacking to define best management, but aspirin and venesection to a target hematocrit should be considered.
Collapse
Affiliation(s)
- Mary Frances McMullin
- Centre for Cancer Research and Cell Biology, Queen's University, Belfast, N. Ireland.
| |
Collapse
|
34
|
Rumi E. Familial chronic myeloproliferative disorders: the state of the art. Hematol Oncol 2008; 26:131-8. [DOI: 10.1002/hon.863] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
|
35
|
Affiliation(s)
- M F McMullin
- Department of Haematology, The Queen's University, Belfast, UK.
| |
Collapse
|
36
|
Abstract
Idiopathic erythrocytosis is an uncommon disease, and is defined by an increase in red blood cell mass. The differential diagnosis of erythrocytosis is extensive, and can be divided into primary and secondary forms. Primary erythrocytoses are due to intrinsic defects in erythroid precursor cells and are characterized by low erythropoietin levels. Secondary erythrocytoses are extrinsic to erythroid progenitors and are characterized by either high or inappropriately normal erythropoietin levels. A distinct subset of secondary erythrocytoses are due to genetic mutations in key proteins of the oxygen-sensing pathway. These proteins constitute the core molecular machinery of oxygen-sensing with respect to red blood cell control. Apart from assigning physiologic roles for these proteins, studies of these rare mutations have (i) revealed the exquisite sensitivity of this pathway to genetic perturbations, (ii) highlighted important functional regions of the proteins, and (iii) provided a basis for potentially targeting this pathway for therapeutic benefit.
Collapse
Affiliation(s)
- Frank S Lee
- Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, 605 Stellar Chance Labs, 422 Curie Boulevard, Philadelphia, PA 19104, USA.
| |
Collapse
|
37
|
Abstract
Erythrocytosis can arise from deregulation of the erythropoietin (Epo) axis resulting from defects in the oxygen-sensing pathway. Epo synthesis is controlled by the hypoxia inducible factor (HIF) complex, composed of an alpha and a beta subunit. There are 2 main alpha subunits, HIF-1 alpha and HIF-2 alpha. Recently, a HIF-2 alpha Gly537Trp mutation was identified in a family with erythrocytosis. This raises the possibility of HIF2A mutations being associated with other cases of erythrocytosis. We now report a subsequent analysis of HIF2A in a cohort of 75 erythrocytosis patients and identify 4 additional patients with novel heterozygous Met535Val and Gly537Arg mutations. All patients presented at a young age with elevated serum Epo. Mutations at Gly-537 account for 4 of 5 HIF2A mutations associated with erythrocytosis. These findings support the importance of HIF-2 alpha in human Epo regulation and warrant investigation of HIF2A in patients with unexplained erythrocytosis.
Collapse
|
38
|
Hickey MM, Lam JC, Bezman NA, Rathmell WK, Simon MC. von Hippel-Lindau mutation in mice recapitulates Chuvash polycythemia via hypoxia-inducible factor-2alpha signaling and splenic erythropoiesis. J Clin Invest 2008; 117:3879-89. [PMID: 17992257 DOI: 10.1172/jci32614] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2007] [Accepted: 08/29/2007] [Indexed: 01/16/2023] Open
Abstract
The R200W mutation in the von Hippel-Lindau (VHL) tumor suppressor protein (pVHL) is unique in that it is not associated with tumor development, but rather with Chuvash polycythemia, a heritable disease characterized by elevated hematocrit and increased serum levels of erythropoietin and VEGF. Previous studies have implicated hypoxia-inducible factor-1alpha (HIF-1alpha) signaling in this disorder, although the effects of this mutation on pVHL function are not fully understood. In order to explore the mechanisms underlying the development of this polycythemia, we generated mice homozygous for the R200W mutation (Vhl(R/R)). Vhl(R/R) mice developed polycythemia highly similar to the human disease. The activity of HIF proteins, specifically the HIF-2alpha isoform, was upregulated in ES cells and tissues from Vhl(R/R) mice. Furthermore, we observed a striking phenotype in Vhl(R/R) spleens, with greater numbers of erythroid progenitors and megakaryocytes and increased erythroid differentiation of Vhl(R/R) splenic cells in vitro. These findings suggest that enhanced expression of key HIF-2alpha genes promotes splenic erythropoiesis, resulting in the development of polycythemia in Vhl(R/R) mice. This mouse model is a faithful recapitulation of this VHL-associated syndrome and represents a useful tool for studying polycythemias and investigating potential therapeutics.
Collapse
Affiliation(s)
- Michele M Hickey
- Abramson Family Cancer Research Institute, Cell and Molecular Biology Graduate Group, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA
| | | | | | | | | |
Collapse
|
39
|
Percy MJ, Furlow PW, Lucas GS, Li X, Lappin TRJ, McMullin MF, Lee FS. A gain-of-function mutation in the HIF2A gene in familial erythrocytosis. N Engl J Med 2008; 358:162-8. [PMID: 18184961 PMCID: PMC2295209 DOI: 10.1056/nejmoa073123] [Citation(s) in RCA: 248] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Hypoxia-inducible factor (HIF) alpha, which has three isoforms, is central to the continuous balancing of the supply and demand of oxygen throughout the body. HIF-alpha is a transcription factor that modulates a wide range of processes, including erythropoiesis, angiogenesis, and cellular metabolism. We describe a family with erythrocytosis and a mutation in the HIF2A gene, which encodes the HIF-2alpha protein. Our functional studies indicate that this mutation leads to stabilization of the HIF-2alpha protein and suggest that wild-type HIF-2alpha regulates erythropoietin production in adults.
Collapse
|
40
|
Abstract
Polycythemia is often associated with erythropoietin (EPO) overexpression and defective oxygen sensing. In normal cells, intracellular oxygen concentrations are directly sensed by prolyl hydroxylase domain (PHD)-containing proteins, which tag hypoxia-inducible factor (HIF) alpha subunits for polyubiquitination and proteasomal degradation by oxygen-dependent prolyl hydroxylation. Here we show that different PHD isoforms differentially regulate HIF-alpha stability in the adult liver and kidney and suppress Epo expression and erythropoiesis through distinct mechanisms. Although Phd1(-/-) or Phd3(-/-) mice had no apparent defects, double knockout of Phd1 and Phd3 led to moderate erythrocytosis. HIF-2alpha, which is known to activate Epo expression, accumulated in the liver. In adult mice deficient for PHD2, the prototypic Epo transcriptional activator HIF-1alpha accumulated in both the kidney and liver. Elevated HIF-1alpha levels were associated with dramatically increased concentrations of both Epo mRNA in the kidney and Epo protein in the serum, which led to severe erythrocytosis. In contrast, heterozygous mutation of Phd2 had no detectable effects on blood homeostasis. These findings suggest that PHD1/3 double deficiency leads to erythrocytosis partly by activating the hepatic HIF-2alpha/Epo pathway, whereas PHD2 deficiency leads to erythrocytosis by activating the renal Epo pathway.
Collapse
|
41
|
Hodges VM, Rainey S, Lappin TR, Maxwell AP. Pathophysiology of anemia and erythrocytosis. Crit Rev Oncol Hematol 2007; 64:139-58. [PMID: 17656101 DOI: 10.1016/j.critrevonc.2007.06.006] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2006] [Revised: 03/02/2007] [Accepted: 06/12/2007] [Indexed: 10/23/2022] Open
Abstract
An increasing understanding of the process of erythropoiesis raises some interesting questions about the pathophysiology, diagnosis and treatment of anemia and erythrocytosis. The mechanisms underlying the development of many of the erythrocytoses, previously characterised as idiopathic, have been elucidated leading to an increased understanding of oxygen homeostasis. Characterisation of anemia and erythrocytosis in relation to serum erythropoietin levels can be a useful addition to clinical diagnostic criteria and provide a rationale for treatment with erythropoiesis stimulating agents (ESAs). Recombinant human erythropoietin as well as other ESAs are now widely used to treat anemias associated with a range of conditions, including chronic kidney disease, chronic inflammatory disorders and cancer. There is also heightened awareness of the potential abuse of ESAs to boost athletic performance in competitive sport. The discovery of erythropoietin receptors outside of the erythropoietic compartment may herald future applications for ESAs in the management of neurological and cardiac diseases. The current controversy concerning optimal hemoglobin levels in chronic kidney disease patients treated with ESAs and the potential negative clinical outcomes of ESA treatment in cancer reinforces the need for cautious evaluation of the pleiotropic effects of ESAs in non-erythroid tissues.
Collapse
Affiliation(s)
- Vivien M Hodges
- Haematology Research Group, Centre for Cancer Research and Cell Biology, Queen's University, Belfast, United Kingdom.
| | | | | | | |
Collapse
|
42
|
Percy MJ, Furlow PW, Beer PA, Lappin TRJ, McMullin MF, Lee FS. A novel erythrocytosis-associated PHD2 mutation suggests the location of a HIF binding groove. Blood 2007; 110:2193-6. [PMID: 17579185 PMCID: PMC1976349 DOI: 10.1182/blood-2007-04-084434] [Citation(s) in RCA: 125] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
The molecular basis of the erythrocytosis group of red cell disorders is incompletely defined. Some cases are due to dysregulation of erythropoietin (Epo) synthesis. The hypoxia inducible transcription factor (HIF) tightly regulates Epo synthesis. HIF in turn is regulated through its alpha subunit, which under normoxic conditions is hydroxylated on specific prolines and targeted for degradation by the von Hippel Lindau (VHL) protein. Several mutations in VHL have been reported in erythrocytosis, but only 1 mutation in the HIF prolyl hydroxylase PHD2 (prolyl hydroxylase domain protein 2) has been described. Here, we report a novel PHD2 mutation, Arg371His, which causes decreased HIF binding, HIF hydroxylase, and HIF inhibitory activities. In the tertiary structure of PHD2, Arg371 lies close to the previously described Pro317Arg mutation site. These findings substantiate PHD2 as a critical enzyme controlling HIF and therefore Epo in humans, and furthermore suggest the location of an active site groove in PHD2 that binds HIF.
Collapse
Affiliation(s)
- Melanie J Percy
- Department of Haematology, Belfast City Hospital, Belfast, United Kingdom.
| | | | | | | | | | | |
Collapse
|
43
|
Tefferi A, Pardanani A. Evaluation of "increased" hemoglobin in the JAK2 mutations era: a diagnostic algorithm based on genetic tests. Mayo Clin Proc 2007; 82:599-604. [PMID: 17493421 DOI: 10.4065/82.5.599] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Recent discoveries in the molecular pathogenesis of both polycythemia vera (PV) and congenital polycythemia (CP) underline the prospect of a genetic diagnosis in these disorders. At the forefront are the mutually exclusive exon 14 (JAK2V617F) and exon 12 JAK2 mutations that are almost always present in PV but not in polycythemias of other causes. Similarly, the molecular basis of CP is being unraveled, and several cases are now associated with germline mutations involving the von Hippel-Lindau (VHL) or erythropoietin receptor (EPOR) genes. Therefore, current diagnostic work-up for acquired polycythemia should start with peripheral blood JAK2 mutation screening, whereas VHL and/or EPOR mutations should be considered when CP is suspected. In all instances, serum erythropoietin measurement provides complementary information; the serum erythropoietin level is expected to be decreased in PV regardless of JAK2 mutation status, increased in VHL mutation-associated CP, and decreased or normal in the presence of an EPOR mutation.
Collapse
Affiliation(s)
- Ayalew Tefferi
- Division of Hematology, College of Medicine, Mayo Clinic, Rochester, MN 55905, USA.
| | | |
Collapse
|
44
|
Kiriakidis S, Esteban MA, Maxwell PH. Genetic insights into the hypoxia-inducible factor (HIF) pathway. ACTA ACUST UNITED AC 2007; 47:288-306. [PMID: 17335877 DOI: 10.1016/j.advenzreg.2006.12.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Serafim Kiriakidis
- Renal Laboratory, Hammersmith Campus, Imperial College London, Du Cane Road, London W12 0NN, UK
| | | | | |
Collapse
|
45
|
Agarwal N, Gordeuk VR, Prchal JT. GenetiC Mechanisms Underlying Regulation of Hemoglobin Mass. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2007; 618:195-210. [DOI: 10.1007/978-0-387-75434-5_15] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
|
46
|
Casarin A, Martella M, Polli R, Leonardi E, Anesi L, Murgia A. Molecular characterization of large deletions in the von Hippel-Lindau (VHL) gene by quantitative real-time PCR: the hypothesis of an alu-mediated mechanism underlying VHL gene rearrangements. Mol Diagn Ther 2006; 10:243-9. [PMID: 16884328 DOI: 10.1007/bf03256463] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
INTRODUCTION Mutations of the von Hippel-Lindau (VHL) gene are responsible for VHL disease. This is a familial autosomal-dominant syndrome, predisposing to the development of benign and malignant tumors, including CNS and retinal hemangioblastomas, pheochromocytomas, and clear cell renal carcinomas. At least 30% of the disease-causing mutations in the VHL gene involve large alterations. Identification of these mutations is not possible using PCR-based mutational scanning methods. Quantitative Southern blot analysis has been traditionally employed for the detection of complete or partial deletions and more complex rearrangements of the gene. METHODS An alternative quantitative method was developed using a combination of quantitative Southern blot analysis and real-time PCR. With this approach, we studied 24 large VHL gene alterations to determine the exact nature of the mutations and to possibly characterize the boundaries of the deleted regions. RESULTS This combined molecular approach showed that all the VHL alterations studied were due to deletions, from which the position in the gene could be more precisely mapped. One of the samples that was completely characterized was found to carry an intragenic 2.2kb deletion with both 5' and 3' breakpoints located within Alu-repeat sequences. CONCLUSION This is the first report on the molecular analysis of large VHL alterations. The results of our study and the complete characterization of a large deletion lead to the hypothesis that an Alu-mediated mechanism may be responsible for the common occurrence of large alterations in the VHL gene.
Collapse
|
47
|
Oudit G, Herzenberg A, Kassiri Z, Wong D, Reich H, Khokha R, Crackower M, Backx P, Penninger J, Scholey J. Angiotensin-Converting Enzyme-2 (ACE2)—A New Player in the Genesis of Glomerular Injury? J Am Soc Nephrol 2006. [DOI: 10.1681/asn.2006080888] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
|
48
|
Smith TG, Brooks JT, Balanos GM, Lappin TR, Layton DM, Leedham DL, Liu C, Maxwell PH, McMullin MF, McNamara CJ, Percy MJ, Pugh CW, Ratcliffe PJ, Talbot NP, Treacy M, Robbins PA. Mutation of von Hippel-Lindau tumour suppressor and human cardiopulmonary physiology. PLoS Med 2006; 3:e290. [PMID: 16768548 PMCID: PMC1479389 DOI: 10.1371/journal.pmed.0030290] [Citation(s) in RCA: 153] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/13/2005] [Accepted: 02/28/2006] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND The von Hippel-Lindau tumour suppressor protein-hypoxia-inducible factor (VHL-HIF) pathway has attracted widespread medical interest as a transcriptional system controlling cellular responses to hypoxia, yet insights into its role in systemic human physiology remain limited. Chuvash polycythaemia has recently been defined as a new form of VHL-associated disease, distinct from the classical VHL-associated inherited cancer syndrome, in which germline homozygosity for a hypomorphic VHL allele causes a generalised abnormality in VHL-HIF signalling. Affected individuals thus provide a unique opportunity to explore the integrative physiology of this signalling pathway. This study investigated patients with Chuvash polycythaemia in order to analyse the role of the VHL-HIF pathway in systemic human cardiopulmonary physiology. METHODS AND FINDINGS Twelve participants, three with Chuvash polycythaemia and nine controls, were studied at baseline and during hypoxia. Participants breathed through a mouthpiece, and pulmonary ventilation was measured while pulmonary vascular tone was assessed echocardiographically. Individuals with Chuvash polycythaemia were found to have striking abnormalities in respiratory and pulmonary vascular regulation. Basal ventilation and pulmonary vascular tone were elevated, and ventilatory, pulmonary vasoconstrictive, and heart rate responses to acute hypoxia were greatly increased. CONCLUSIONS The features observed in this small group of patients with Chuvash polycythaemia are highly characteristic of those associated with acclimatisation to the hypoxia of high altitude. More generally, the phenotype associated with Chuvash polycythaemia demonstrates that VHL plays a major role in the underlying calibration and homeostasis of the respiratory and cardiovascular systems, most likely through its central role in the regulation of HIF.
Collapse
Affiliation(s)
- Thomas G Smith
- 1Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford, United Kingdom
| | - Jerome T Brooks
- 1Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford, United Kingdom
| | - George M Balanos
- 2School of Sport and Exercise Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Terence R Lappin
- 3Centre for Cancer Research and Cell Biology, Queen's University, Belfast, United Kingdom
| | - D. Mark Layton
- 4Department of Haematology, Imperial College of Science, Technology, and Medicine, London, United Kingdom
| | - Dawn L Leedham
- 5Diagnostics, Therapies, and Cancer Division, Chase Farm Hospital, Middlesex, United Kingdom
| | - Chun Liu
- 1Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford, United Kingdom
| | - Patrick H Maxwell
- 6Renal Section, Imperial College of Science, Technology, and Medicine, London, United Kingdom
| | - Mary F McMullin
- 7Department of Haematology, Queen's University, Belfast City Hospital, Belfast, United Kingdom
| | | | - Melanie J Percy
- 7Department of Haematology, Queen's University, Belfast City Hospital, Belfast, United Kingdom
| | - Christopher W Pugh
- 9Nuffield Department of Clinical Medicine, University of Oxford, Oxford, United Kingdom
| | - Peter J Ratcliffe
- 9Nuffield Department of Clinical Medicine, University of Oxford, Oxford, United Kingdom
| | - Nick P Talbot
- 1Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford, United Kingdom
| | - Marilyn Treacy
- 5Diagnostics, Therapies, and Cancer Division, Chase Farm Hospital, Middlesex, United Kingdom
| | - Peter A Robbins
- 1Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford, United Kingdom
- * To whom correspondence should be addressed. E-mail:
| |
Collapse
|
49
|
Abstract
Idiopathic erythrocytosis (IE) is a rare condition in which there is an increase in red cell mass and hematocrit. As it is typically driven by elevated or inappropriately normal erythropoietin (Epo) levels, it has the potential to reveal the identities of proteins involved in the oxygen sensing pathway that regulates the transcription factor, Hypoxia Inducible Factor (HIF), and hence Epo production in humans. One example of this is provided by Chuvash polycythemia, a form of erythrocytosis due to a mutation in the von Hippel Lindau tumor suppressor protein (VHL), a component of an E3 ubiquitin ligase complex that targets hydroxylated HIF for degradation. A recent report of familial erythrocytosis now implicates a different protein, Prolyl Hydroxylase Domain protein 2 (PHD2), which is an enzyme that hydroxylates HIF.
Collapse
Affiliation(s)
- Frank S. Lee
- Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA
- Correspondence to: Frank S. Lee; Department of Pathology and Laboratory Medicine; University of Pennsylvania School of Medicine; 605 Stellar Chance Labs; 422 Curie Blvd.; Philadelphia, Pennsylvania 19104 USA; Tel.: 215.898.4701; Fax: 215.573.2272; E-mail: Mary Frances McMullin; Department of Haematology, Queen's University; Belfast, Northern Ireland, BT9 7AB, UK; Tel: +44−2890−263733; Fax: +44−2890−263870; E-mail:
| | - Melanie J. Percy
- †Department of Haematology, Belfast City Hospital, Belfast, Northern Ireland, BT9 7AB, UK
| | - Mary Frances McMullin
- ¶ Department of Haematology, Queen's University, Belfast, Northern Ireland, BT9 7AB, UK
- Correspondence to: Frank S. Lee; Department of Pathology and Laboratory Medicine; University of Pennsylvania School of Medicine; 605 Stellar Chance Labs; 422 Curie Blvd.; Philadelphia, Pennsylvania 19104 USA; Tel.: 215.898.4701; Fax: 215.573.2272; E-mail: Mary Frances McMullin; Department of Haematology, Queen's University; Belfast, Northern Ireland, BT9 7AB, UK; Tel: +44−2890−263733; Fax: +44−2890−263870; E-mail:
| |
Collapse
|
50
|
Percy MJ, Zhao Q, Flores A, Harrison C, Lappin TRJ, Maxwell PH, McMullin MF, Lee FS. A family with erythrocytosis establishes a role for prolyl hydroxylase domain protein 2 in oxygen homeostasis. Proc Natl Acad Sci U S A 2006; 103:654-9. [PMID: 16407130 PMCID: PMC1334658 DOI: 10.1073/pnas.0508423103] [Citation(s) in RCA: 245] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The number of red blood cells is normally tightly regulated by a classic homeostatic mechanism based on oxygen sensing in the kidney. Decreased oxygen delivery resulting from anemia induces the production of erythropoietin, which increases red cell production and hence oxygen delivery. Investigations of erythropoietin regulation identified the transcription factor hypoxia-inducible factor (HIF). HIF is now recognized as being a key regulator of genes that function in a comprehensive range of processes besides erythropoiesis, including energy metabolism and angiogenesis. HIF itself is regulated through the alpha-subunit, which is hydroxylated in the presence of oxygen by a family of three prolyl hydroxylase domain proteins (PHDs)/HIF prolyl hydroxylases/egg-laying-defective nine enzymes. Hydroxylation allows capture by the von Hippel-Lindau tumor suppressor gene product, ubiquitination, and destruction by the proteasome. Here we describe an inherited mutation in a mammalian PHD enzyme. We show that this mutation in PHD2 results in a marked decrease in enzyme activity and is associated with familial erythrocytosis, identifying a previously unrecognized cause of this condition. Our findings indicate that PHD2 is critical for normal regulation of HIF in humans.
Collapse
Affiliation(s)
- Melanie J Percy
- Department of Haematology, Belfast City Hospital, Belfast BT9 7AB, Northern Ireland, United Kingdom
| | | | | | | | | | | | | | | |
Collapse
|