1
|
Mallik N, Das R, Malhotra P, Sharma P. Congenital erythrocytosis. Eur J Haematol 2021; 107:29-37. [PMID: 33840141 DOI: 10.1111/ejh.13632] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Accepted: 04/07/2021] [Indexed: 12/13/2022]
Abstract
Erythrocytosis, or increased red cell mass, may be labeled as primary or secondary, depending on whether the molecular defect is intrinsic to the red blood cells/their precursors or extrinsic to them, the latter being typically associated with elevated erythropoietin (EPO) levels. Inherited/congenital erythrocytosis (CE) of both primary and secondary types is increasingly recognized as the cause in many patients in whom acquired, especially neoplastic causes have been excluded. During the past two decades, the underlying molecular mechanisms of CE are increasingly getting unraveled. Gain-in-function mutations in the erythropoietin receptor gene were among the first to be characterized in a disorder termed primary familial and congenital polycythemia. Another set of mutations affect the components of the oxygen-sensing pathway. Under normoxic conditions, the hypoxia-inducible factor (HIF), upon hydroxylation by the prolyl-4-hydroxylase domain protein 2 (PHD2) enzyme, is degraded by the von Hippel-Lindau protein. In hypoxic conditions, failure of prolyl hydroxylation leads to stabilization of HIF and activation of the EPO gene. CE has been found to be caused by loss-of-function mutations in VHL and PHD2/EGLN1 as well as gain-of-function mutations in HIF-2α (EPAS1), all resulting in constitutive activation of EPO signaling. Apart from these, globin gene mutations leading to formation of high oxygen affinity hemoglobins also cause CE. Rarely, bisphosphoglycerate mutate mutations, affecting the 2,3-bisphosphoglycerate levels, can increase the oxygen affinity of hemoglobin and cause CE. This narrative review examines the current mutational spectrum of CE and the distinctive pathogenetic mechanisms that give rise to this increasingly recognized condition in various parts of the world.
Collapse
Affiliation(s)
- Nabhajit Mallik
- Department of Hematology, Postgraduate Institute of Medical Education & Research, Chandigarh, India
| | - Reena Das
- Department of Hematology, Postgraduate Institute of Medical Education & Research, Chandigarh, India
| | - Pankaj Malhotra
- Adult Clinical Hematology Unit, Department of Internal Medicine, Postgraduate Institute of Medical Education & Research, Chandigarh, India
| | - Prashant Sharma
- Department of Hematology, Postgraduate Institute of Medical Education & Research, Chandigarh, India
| |
Collapse
|
2
|
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
|
3
|
Perrotta S, Cucciolla V, Ferraro M, Ronzoni L, Tramontano A, Rossi F, Scudieri AC, Borriello A, Roberti D, Nobili B, Cappellini MD, Oliva A, Amendola G, Migliaccio AR, Mancuso P, Martin-Padura I, Bertolini F, Yoon D, Prchal JT, Della Ragione F. EPO receptor gain-of-function causes hereditary polycythemia, alters CD34 cell differentiation and increases circulating endothelial precursors. PLoS One 2010; 5:e12015. [PMID: 20700488 PMCID: PMC2916842 DOI: 10.1371/journal.pone.0012015] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2010] [Accepted: 07/03/2010] [Indexed: 02/03/2023] Open
Abstract
Background Gain-of-function of erythropoietin receptor (EPOR) mutations represent the major cause of primary hereditary polycythemia. EPOR is also found in non-erythroid tissues, although its physiological role is still undefined. Methodology/Principal Findings We describe a family with polycythemia due to a heterozygous mutation of the EPOR gene that causes a G→T change at nucleotide 1251 of exon 8. The novel EPOR G1251T mutation results in the replacement of a glutamate residue by a stop codon at amino acid 393. Differently from polycythemia vera, EPOR G1251T CD34+ cells proliferate and differentiate towards the erythroid phenotype in the presence of minimal amounts of EPO. Moreover, the affected individuals show a 20-fold increase of circulating endothelial precursors. The analysis of erythroid precursor membranes demonstrates a heretofore undescribed accumulation of the truncated EPOR, probably due to the absence of residues involved in the EPO-dependent receptor internalization and degradation. Mutated receptor expression in EPOR-negative cells results in EPOR and Stat5 phosphorylation. Moreover, patient erythroid precursors present an increased activation of EPOR and its effectors, including Stat5 and Erk1/2 pathway. Conclusions/Significance Our data provide an unanticipated mechanism for autosomal dominant inherited polycythemia due to a heterozygous EPOR mutation and suggest a regulatory role of EPO/EPOR pathway in human circulating endothelial precursors homeostasis.
Collapse
Affiliation(s)
- Silverio Perrotta
- Department of Pediatrics, Second University of Naples, Naples, Italy
| | - Valeria Cucciolla
- Department of Biochemistry and Biophysics “F. Cedrangolo”, Second University of Naples, Naples, Italy
| | - Marcella Ferraro
- Department of Pediatrics, Second University of Naples, Naples, Italy
| | - Luisa Ronzoni
- Foundation Ospedale Maggiore Policlinico IRCCS, University of Milan, Milan, Italy
| | - Annunziata Tramontano
- Department of Biochemistry and Biophysics “F. Cedrangolo”, Second University of Naples, Naples, Italy
| | - Francesca Rossi
- Department of Pediatrics, Second University of Naples, Naples, Italy
| | - Anna Chiara Scudieri
- Department of Biochemistry and Biophysics “F. Cedrangolo”, Second University of Naples, Naples, Italy
| | - Adriana Borriello
- Department of Biochemistry and Biophysics “F. Cedrangolo”, Second University of Naples, Naples, Italy
| | - Domenico Roberti
- Department of Pediatrics, Second University of Naples, Naples, Italy
| | - Bruno Nobili
- Department of Pediatrics, Second University of Naples, Naples, Italy
| | | | - Adriana Oliva
- Department of Pediatrics, Second University of Naples, Naples, Italy
| | - Giovanni Amendola
- Ematologia-Oncologia Pediatrica, Ospedale di Nocera Inferiore, Nocera Inferiore, Italy
| | | | - Patrizia Mancuso
- Laboratory of Hematology-Oncology, European Institute of Oncology, Milan, Italy
| | - Ines Martin-Padura
- Laboratory of Hematology-Oncology, European Institute of Oncology, Milan, Italy
| | - Francesco Bertolini
- Laboratory of Hematology-Oncology, European Institute of Oncology, Milan, Italy
| | - Donghoon Yoon
- Hematology Division, School of Medicine, University of Utah and VAH, Salt Lake City, Utah, United States of America
| | - Josef T. Prchal
- Hematology Division, School of Medicine, University of Utah and VAH, Salt Lake City, Utah, United States of America
| | - Fulvio Della Ragione
- Department of Biochemistry and Biophysics “F. Cedrangolo”, Second University of Naples, Naples, Italy
- * E-mail:
| |
Collapse
|
4
|
Huang LJ, Shen YM, Bulut GB. Advances in understanding the pathogenesis of primary familial and congenital polycythaemia. Br J Haematol 2010; 148:844-52. [PMID: 20096014 DOI: 10.1111/j.1365-2141.2009.08069.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Primary familial and congenital polycythemia (PFCP) is an autosomal-dominant proliferative disorder characterized by erythrocytosis and hypersensitivity of erythroid progenitors to erythropoietin (Epo). Several lines of evidence suggest a causal role of truncated erythropoietin receptor (EpoR) in this disease. In this review, we discuss PFCP in the context of erythrocytosis and EpoR signalling. We focus on recent studies describing mechanisms underlying Epo-dependent EpoR down-regulation. One mechanism depends on internalization mediated through the p85 regulatory subunit of the Phosphoinositide 3-Kinase, and the other utilizes ubiquitin-based proteasomal degradation. Truncated PFCP EpoRs are not properly down-regulated upon stimulation, underscoring the importance of these mechanisms in the pathogenesis of PFCP.
Collapse
Affiliation(s)
- Lily J Huang
- Department of Cell Biology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390-9039, USA.
| | | | | |
Collapse
|