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Delamare M, Le Roy A, Pacault M, Schmitt L, Garrec C, Maaziz N, Myllykoski M, Rimbert A, Karaghiannis V, Aral B, Catherwood M, Airaud F, Mansour-Hendili L, Hoogewijs D, Peroni E, Idriss S, Lesieur V, Caillaud A, Si-Tayeb K, Chariau C, Gaignerie A, Rab M, Haferlach T, Meggendorfer M, Bézieau S, Benetti A, Casadevall N, Hirsch P, Rose C, Wemeau M, Galacteros F, Cassinat B, Bellosillo B, Bento C, Van Wijk R, Petrides PE, Randi ML, McMullin MF, Koivunen P, Girodon F, Gardie B. Characterization of genetic variants in the EGLN1/PHD2 gene identified in a European collection of patients with erythrocytosis. Haematologica 2023; 108:3068-3085. [PMID: 37317877 PMCID: PMC10620589 DOI: 10.3324/haematol.2023.282913] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Accepted: 06/06/2023] [Indexed: 06/16/2023] Open
Abstract
Hereditary erythrocytosis is a rare hematologic disorder characterized by an excess of red blood cell production. Here we describe a European collaborative study involving a collection of 2,160 patients with erythrocytosis sequenced in ten different laboratories. We focused our study on the EGLN1 gene and identified 39 germline missense variants including one gene deletion in 47 probands. EGLN1 encodes the PHD2 prolyl 4-hydroxylase, a major inhibitor of hypoxia-inducible factor. We performed a comprehensive study to evaluate the causal role of the identified PHD2 variants: (i) in silico studies of localization, conservation, and deleterious effects; (ii) analysis of hematologic parameters of carriers identified in the UK Biobank; (iii) functional studies of the protein activity and stability; and (iv) a comprehensive study of PHD2 splicing. Altogether, these studies allowed the classification of 16 pathogenic or likely pathogenic mutants in a total of 48 patients and relatives. The in silico studies extended to the variants described in the literature showed that a minority of PHD2 variants can be classified as pathogenic (36/96), without any differences from the variants of unknown significance regarding the severity of the developed disease (hematologic parameters and complications). Here, we demonstrated the great value of federating laboratories working on such rare disorders in order to implement the criteria required for genetic classification, a strategy that should be extended to all hereditary hematologic diseases.
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Affiliation(s)
- Marine Delamare
- Ecole Pratique des Hautes Etudes, EPHE, Université PSL, France; Université de Nantes, CNRS, INSERM, l'institut du thorax, F-44000 Nantes
| | - Amandine Le Roy
- Ecole Pratique des Hautes Etudes, EPHE, Université PSL, France; Université de Nantes, CNRS, INSERM, l'institut du thorax, F-44000 Nantes
| | - Mathilde Pacault
- Université de Nantes, CNRS, INSERM, l'institut du thorax, F-44000 Nantes, France; Service de Génétique Médicale, CHU de Nantes, Nantes
| | - Loïc Schmitt
- Ecole Pratique des Hautes Etudes, EPHE, Université PSL, France; Université de Nantes, CNRS, INSERM, l'institut du thorax, F-44000 Nantes
| | - Céline Garrec
- Service de Génétique Médicale, CHU de Nantes, Nantes
| | - Nada Maaziz
- Service d'Hématologie Biologique, Pôle Biologie, CHU de Dijon, Dijon
| | - Matti Myllykoski
- Biocenter Oulu and Faculty of Biochemistry and Molecular Medicine, Oulu Center for Cell-Matrix Research, University of Oulu, 90014 Oulu, Finland. 90014 Oulu
| | - Antoine Rimbert
- Université de Nantes, CNRS, INSERM, l'institut du thorax, F-44000 Nantes
| | - Valéna Karaghiannis
- Ecole Pratique des Hautes Etudes, EPHE, Université PSL, France; Université de Nantes, CNRS, INSERM, l'institut du thorax, F-44000 Nantes
| | - Bernard Aral
- Service d'Hématologie Biologique, Pôle Biologie, CHU de Dijon, Dijon
| | | | | | - Lamisse Mansour-Hendili
- Département de Biochimie-Biologie Moléculaire, Pharmacologie, Génétique Médicale AP-HP, Hôpitaux Universitaires Henri Mondor, Créteil, France; Université Paris-Est Créteil, IMRB Equipe Pirenne, Laboratoire d'excellence LABEX GRex, Créteil
| | - David Hoogewijs
- Section of Medicine, Department of Endocrinology, Metabolism and Cardiovascular System, University of Fribourg, CH-1700 Fribourg, Switzerland; National Center of Competence in Research "Kidney.CH"
| | - Edoardo Peroni
- Immunology and Molecular Oncology Unit, Veneto Institute of Oncology, IOV-IRCCS, 35128 Padova, Italy; Medical Genetics Unit, Mater Domini University Hospital, 88100 Catanzaro
| | - Salam Idriss
- Université de Nantes, CNRS, INSERM, l'institut du thorax, F-44000 Nantes
| | - Valentine Lesieur
- Université de Nantes, CNRS, INSERM, l'institut du thorax, F-44000 Nantes
| | - Amandine Caillaud
- Université de Nantes, CNRS, INSERM, l'institut du thorax, F-44000 Nantes
| | - Karim Si-Tayeb
- Université de Nantes, CNRS, INSERM, l'institut du thorax, F-44000 Nantes
| | - Caroline Chariau
- Nantes Université, CHU Nantes, CNRS, Inserm, BioCore, FR-44000, Nantes
| | - Anne Gaignerie
- Nantes Université, CHU Nantes, CNRS, Inserm, BioCore, FR-44000, Nantes
| | - Minke Rab
- Central Diagnostic Laboratory - Research, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands; Department of Hematology, University Medical Center Utrecht, Utrecht University, Utrecht
| | | | | | - Stéphane Bézieau
- Université de Nantes, CNRS, INSERM, l'institut du thorax, F-44000 Nantes, France; Service de Génétique Médicale, CHU de Nantes, Nantes
| | - Andrea Benetti
- Department of Medicine-DIMED, University of Padua, Via Giustiniani 2, 35128, Padua
| | - Nicole Casadevall
- Sorbonne Université, INSERM, Centre de Recherche Saint-Antoine, CRSA, AP-HP, SIRIC CURAMUS, Hôpital Saint-Antoine, Service d'Hématologie Biologique, 75012, Paris
| | - Pierre Hirsch
- Sorbonne Université, INSERM, Centre de Recherche Saint-Antoine, CRSA, AP-HP, SIRIC CURAMUS, Hôpital Saint-Antoine, Service d'Hématologie Biologique, 75012, Paris
| | - Christian Rose
- Service d'onco-hématologie, Saint-Vincent de Paul Hospital, Boulevard de Belfort, Université Catholique de Lille, Univ. Nord de France, F-59000 Lille
| | - Mathieu Wemeau
- Hematology Department, Claude Huriez Hospital, Lille Hospital, 59000 Lille
| | - Frédéric Galacteros
- Département de Biochimie-Biologie Moléculaire, Pharmacologie, Génétique Médicale AP-HP, Hôpitaux Universitaires Henri Mondor, Créteil, France; Red Cell Disease Referral Center-UMGGR, AP-HP, Hôpitaux Universitaires Henri Mondor, Créteil
| | - Bruno Cassinat
- Université Paris Cité, APHP, Hôpital Saint-Louis, Laboratoire de Biologie Cellulaire, Paris
| | | | - Celeste Bento
- Hematology Department, Centro Hospitalar e Universitário de Coimbra; CIAS, University of Coimbra
| | - Richard Van Wijk
- Central Diagnostic Laboratory - Research, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands; Department of Hematology, University Medical Center Utrecht, Utrecht University, Utrecht
| | - Petro E Petrides
- Hematology Oncology Center and Ludwig-Maximilians-University Munich Medical School, Munich
| | - Maria Luigia Randi
- Department of Medicine-DIMED, University of Padua, Via Giustiniani 2, 35128, Padua
| | - Mary Frances McMullin
- Belfast Health and Social Care Trust, Belfast N.Ireland; Queen's University, Belfast, N. Ireland
| | - Peppi Koivunen
- Biocenter Oulu and Faculty of Biochemistry and Molecular Medicine, Oulu Center for Cell-Matrix Research, University of Oulu, 90014 Oulu, Finland. 90014 Oulu
| | - François Girodon
- Service d'Hématologie Biologique, Pôle Biologie, CHU de Dijon, Dijon, France; Inserm U1231, Université de Bourgogne, Dijon, France; Laboratoire d'Excellence GR-Ex
| | - Betty Gardie
- Ecole Pratique des Hautes Etudes, EPHE, Université PSL, France; Université de Nantes, CNRS, INSERM, l'institut du thorax, F-44000 Nantes, France; Laboratoire d'Excellence GR-Ex
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Gangat N, Szuber N, Tefferi A. JAK2 unmutated erythrocytosis: 2023 Update on diagnosis and management. Am J Hematol 2023; 98:965-981. [PMID: 36966432 DOI: 10.1002/ajh.26920] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Revised: 03/18/2023] [Accepted: 03/22/2023] [Indexed: 03/27/2023]
Abstract
DISEASE OVERVIEW JAK2 unmutated or non-polycythemia vera (PV) erythrocytosis encompasses a heterogenous spectrum of hereditary and acquired entities. DIAGNOSIS Foremost in the evaluation of erythrocytosis is the exclusion of PV through JAK2 (inclusive of exons 12-15) mutation screening. Initial assessment should also include gathering of previous records on hematocrit (Hct) and hemoglobin (Hgb) levels, in order to streamline the diagnostic process by first distinguishing longstanding from acquired erythrocytosis; subsequent subcategorization is facilitated by serum erythropoietin (Epo) measurement, germline mutation screening, and review of historical data, including comorbid conditions and medication list. Hereditary erythrocytosis constitutes the main culprit in the context of longstanding erythrocytosis, especially when associated with a positive family history. In this regard, a subnormal serum Epo level suggests EPO receptor mutation. Otherwise, considerations include those associated with decreased (high oxygen affinity Hgb variants, 2,3-bisphosphoglycerate deficiency, PIEZO1 mutations, methemoglobinemia) or normal oxygen tension at 50% Hgb saturation (P50). The latter include germline oxygen sensing pathway (HIF2A-PHD2-VHL) and other rare mutations. Acquired erythrocytosis commonly results from central (e.g., cardiopulmonary disease, high-altitude habitat) or peripheral (e.g., renal artery stenosis) hypoxia. Other noteworthy conditions associated with acquired erythrocytosis include Epo-producing tumors (e.g., renal cell carcinoma, cerebral hemangioblastoma) and drugs (e.g., testosterone, erythropoiesis stimulating agents, sodium-glucose cotransporter-2 inhibitors). Idiopathic erythrocytosis is an ill-defined terminology that presumes the existence of an increased Hgb/Hct level without an identifiable etiology. Such classification often lacks accounting for normal outliers and is marred by truncated diagnostic evaluation. MANAGEMENT Current consensus treatment guidelines are not supported by hard evidence and their value is further undermined by limited phenotypic characterization and unfounded concerns for thrombosis. We are of the opinion that cytoreductive therapy and indiscriminate use of phlebotomy should be avoided in the treatment of non-clonal erythrocytosis. However, it is reasonable to consider therapeutic phlebotomy if one were to demonstrate value in symptom control, with frequency determined by symptoms rather than Hct level. In addition, cardiovascular risk optimization and low dose aspirin is often advised. FUTURE DIRECTIONS Advances in molecular hematology might result in better characterization of "idiopathic erythrocytosis" and expansion of the repertoire for germline mutations in hereditary erythrocytosis. Prospective controlled studies are needed to clarify potential pathology from JAK2 unmutated erythrocytosis, as well as to document the therapeutic value of phlebotomy.
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Affiliation(s)
- Naseema Gangat
- Division of Hematology, Department of Internal Medicine, Mayo Clinic, Rochester, Minnesota, USA
| | - Natasha Szuber
- Department of Hematology, Université de Montréal, Montréal, Quebec, Canada
| | - Ayalew Tefferi
- Division of Hematology, Department of Internal Medicine, Mayo Clinic, Rochester, Minnesota, USA
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Song D, Peng K, Palmer BE, Lee FS. The ribosomal chaperone NACA recruits PHD2 to cotranslationally modify HIF-α. EMBO J 2022; 41:e112059. [PMID: 36219563 PMCID: PMC9670199 DOI: 10.15252/embj.2022112059] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Revised: 08/23/2022] [Accepted: 09/23/2022] [Indexed: 01/13/2023] Open
Abstract
Prolyl hydroxylase domain protein 2 (PHD2)-catalyzed modification of hypoxia-inducible factor (HIF)-α is a key event in oxygen sensing. We previously showed that the zinc finger of PHD2 binds to a Pro-Xaa-Leu-Glu (PXLE) motif. Here, we show that the zinc finger binds to this motif in the ribosomal chaperone nascent polypeptide complex-α (NACA). This recruits PHD2 to the translation machinery to cotranslationally modify HIF-α. Importantly, this cotranslational modification is enhanced by a translational pause sequence in HIF-α. Mice with a knock-in Naca gene mutation that abolishes the PXLE motif display erythrocytosis, a reflection of HIF pathway dysregulation. In addition, human erythrocytosis-associated mutations in the zinc finger of PHD2 ablate interaction with NACA. Tibetans, who have adapted to the hypoxia of high altitude, harbor a PHD2 variant that we previously showed displays a defect in zinc finger binding to p23, a PXLE-containing HSP90 cochaperone. We show here that Tibetan PHD2 maintains interaction with NACA, thereby showing differential interactions with PXLE-containing proteins and providing an explanation for why Tibetans are not predisposed to erythrocytosis.
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Affiliation(s)
- Daisheng Song
- Department of Pathology and Laboratory Medicine, Perelman School of MedicineUniversity of PennsylvaniaPhiladelphiaPAUSA
| | - Kai Peng
- Department of Pathology and Laboratory Medicine, Perelman School of MedicineUniversity of PennsylvaniaPhiladelphiaPAUSA
- Present address:
Chime BiologicsWuhanChina
| | - Bradleigh E Palmer
- Department of Pathology and Laboratory Medicine, Perelman School of MedicineUniversity of PennsylvaniaPhiladelphiaPAUSA
- Present address:
Department of BiologyJohns Hopkins UniversityBaltimoreMDUSA
| | - Frank S Lee
- Department of Pathology and Laboratory Medicine, Perelman School of MedicineUniversity of PennsylvaniaPhiladelphiaPAUSA
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Mutational Landscape of Patients Referred for Elevated Hemoglobin Level. Curr Oncol 2022; 29:7209-7217. [PMID: 36290845 PMCID: PMC9600330 DOI: 10.3390/curroncol29100568] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Revised: 09/13/2022] [Accepted: 09/26/2022] [Indexed: 01/13/2023] Open
Abstract
Background: Since the identification of JAK2 V617F and exon 12 mutations as driver mutations in polycythemia vera (PV) in 2005, molecular testing of these mutations for patients with erythrocytosis has become a routine clinical practice. However, the incidence of myeloid mutations other than the common JAK2 V617F mutation in unselected patients referred for elevated hemoglobin is not well studied. This study aimed to characterize the mutational landscape in a real-world population of patients referred for erythrocytosis using a targeted next-generation sequencing (NGS)-based assay. Method: A total of 529 patients (hemoglobin levels >160 g/L in females or >165 g/L in males) were assessed between January 2018 and May 2021 for genetic variants using the Oncomine Myeloid Research Assay (ThermoFisher Scientific, Waltham, MA, USA) targeting 40 key genes with diagnostic and prognostic implications in hematological conditions (17 full genes and 23 genes with clinically relevant "hotspot" regions) and a panel of 29 fusion driver genes (>600 fusion partners). Results: JAK2 mutations were detected in 10.9% (58/529) of patients, with 57 patients positive for JAK2 V617F, while one patient had a JAK2 exon 12 mutation. Additional mutations were detected in 34.5% (20/58) of JAK2-positive patients: TET2 (11; 19%), DNMT3A (2;3.4%), ASXL1 (2; 3.4%), SRSF2 (2; 3.4%), BCOR (1; 1.7%), TP53 (1; 1.7%), and ZRSR2 (1; 1.7%). Diagnosis of PV was suspected in 2 JAK2-negative patients based on the 2016 World Health Organization (WHO) diagnostic criteria. Notably, one patient carried mutations in the SRSF2 and TET2 genes, and the other patient carried mutations in the SRSF2, IDH2, and ASXL1 genes. Three JAK2-negative patients with elevated hemoglobin who tested positive for BCR/ABL1 fusion were diagnosed with chronic myeloid leukemia (CML) and excluded from further analysis. The remaining 466 JAK2-negative patients were diagnosed with secondary erythrocytosis and mutations were found in 6% (28/466) of these cases. Conclusion: Mutations other than JAK2 mutations were frequently identified in patients referred for erythrocytosis, with mutations in the TET2, DNMT3A, and ASXL1 genes being detected in 34.5% of JAK2-positive PV patients. The presence of additional mutations, such as ASXL1 mutations, in this population has implications for prognosis. Both the incidence and mutation type identified in patients with secondary erythrocytosis likely reflects incidental, age-associated clonal hematopoiesis of indeterminate potential (CHIP).
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NGS Evaluation of a Bernese Cohort of Unexplained Erythrocytosis Patients. Genes (Basel) 2021; 12:genes12121951. [PMID: 34946900 PMCID: PMC8701725 DOI: 10.3390/genes12121951] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2021] [Revised: 11/23/2021] [Accepted: 12/01/2021] [Indexed: 01/06/2023] Open
Abstract
(1) Background: Clinical and molecular data on patients with unexplained erythrocyto-sis is sparse. We aimed to analyze the clinical and molecular features of patients with congenital erythrocytosis in our tertiary reference center. (2) Methods: In 34 patients with unexplained erythrocytosis, a 13-gene Next-Generation Sequencing erythrocytosis panel developed at our center was conducted. (3) Results: In 6/34 (18%) patients, eight different heterozygous gene variants were found. These patients were, therefore, diagnosed with congenital erythrocytosis. Two patients had two different gene variants each. All variants were characterized as variants of unknown significance as they had not previously been described in the literature. The rest of the patients (28/34, 82%) had no detected gene variants. (4) Conclusions: Our experience shows that the NGS panel can be helpful in determining the reasons for persistent, unexplained erythrocytosis. In our cohort of patients with erythrocytosis, we identified some, thus far unknown, gene variants which may explain the clinical picture. However, further investigations are needed to determine the relationship between the molecular findings and the phenotype.
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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.
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Gangat N, Szuber N, Pardanani A, Tefferi A. JAK2 unmutated erythrocytosis: current diagnostic approach and therapeutic views. Leukemia 2021; 35:2166-2181. [PMID: 34021251 PMCID: PMC8324477 DOI: 10.1038/s41375-021-01290-6] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 04/28/2021] [Accepted: 05/06/2021] [Indexed: 02/08/2023]
Abstract
JAK2 unmutated or non-polycythemia vera (PV) erythrocytosis encompasses both hereditary and acquired conditions. A systematic diagnostic approach begins with documentation of historical hematocrit (Hct)/hemoglobin (Hgb) measurements and classification of the process as life-long/unknown duration or acquired. Further investigation in both categories is facilitated by determination of serum erythropoietin level (EPO). Workup for hereditary/congenital erythrocytosis requires documentation of family history and laboratory screening for high-oxygen affinity hemoglobin variants, 2, 3 biphosphoglycerate deficiency, and germline mutations that are known to alter cellular oxygen sensing (e.g., PHD2, HIF2A, VHL) or EPO signaling (e.g., EPOR mutations); the latter is uniquely associated with subnormal EPO. Acquired erythrocytosis is often elicited by central or peripheral hypoxia resulting from cardiopulmonary disease/high-altitude dwelling or renal artery stenosis, respectively; EPO in the former instance is often normal (compensated by negative feed-back). Other conditions associated with acquired erythrocytosis include EPO-producing tumors and the use of drugs that promote erythropoiesis (e.g., testosterone, erythropoiesis stimulating agents). "Idiopathic erythrocytosis" loosely refers to an otherwise not explained situation. Historically, management of non-PV erythrocytosis has been conflicted by unfounded concerns regarding thrombosis risk, stemming from limited phenotypic characterization, save for Chuvash polycythemia, well-known for its thrombotic tendency. In general, cytoreductive therapy should be avoided and phlebotomy is seldom warranted where frequency is determined by symptom control rather than Hct threshold. Although not supported by hard evidence, cardiovascular risk optimization and low-dose aspirin use are often advised. Application of modern genetic tests and development of controlled therapeutic intervention trials are needed to advance current clinical practice.
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Affiliation(s)
- Naseema Gangat
- grid.66875.3a0000 0004 0459 167XDivision of Hematology, Department of Internal Medicine, Mayo Clinic, Rochester, MN USA
| | - Natasha Szuber
- grid.14848.310000 0001 2292 3357Department of Hematology, Université de Montréal, Montréal, QC Canada
| | - Animesh Pardanani
- grid.66875.3a0000 0004 0459 167XDivision of Hematology, Department of Internal Medicine, Mayo Clinic, Rochester, MN USA
| | - Ayalew Tefferi
- grid.66875.3a0000 0004 0459 167XDivision of Hematology, Department of Internal Medicine, Mayo Clinic, Rochester, MN USA
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Hypoxia Pathway Proteins are Master Regulators of Erythropoiesis. Int J Mol Sci 2020; 21:ijms21218131. [PMID: 33143240 PMCID: PMC7662373 DOI: 10.3390/ijms21218131] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2020] [Revised: 10/21/2020] [Accepted: 10/28/2020] [Indexed: 02/06/2023] Open
Abstract
Erythropoiesis is a complex process driving the production of red blood cells. During homeostasis, adult erythropoiesis takes place in the bone marrow and is tightly controlled by erythropoietin (EPO), a central hormone mainly produced in renal EPO-producing cells. The expression of EPO is strictly regulated by local changes in oxygen partial pressure (pO2) as under-deprived oxygen (hypoxia); the transcription factor hypoxia-inducible factor-2 induces EPO. However, erythropoiesis regulation extends beyond the well-established hypoxia-inducible factor (HIF)-EPO axis and involves processes modulated by other hypoxia pathway proteins (HPPs), including proteins involved in iron metabolism. The importance of a number of these factors is evident as their altered expression has been associated with various anemia-related disorders, including chronic kidney disease. Eventually, our emerging understanding of HPPs and their regulatory feedback will be instrumental in developing specific therapies for anemic patients and beyond.
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Dey A, Prabhudesai S, Zhang Y, Rao G, Thirugnanam K, Hossen MN, Dwivedi SKD, Ramchandran R, Mukherjee P, Bhattacharya R. Cystathione β-synthase regulates HIF-1α stability through persulfidation of PHD2. SCIENCE ADVANCES 2020; 6:eaaz8534. [PMID: 32937467 PMCID: PMC7458453 DOI: 10.1126/sciadv.aaz8534] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Accepted: 05/20/2020] [Indexed: 05/10/2023]
Abstract
The stringent expression of the hypoxia inducible factor-1α (HIF-1α) is critical to a variety of pathophysiological conditions. We reveal that, in normoxia, enzymatic action of cystathionine β-synthase (CBS) produces H2S, which persulfidates prolyl hydroxylase 2 (PHD2) at residues Cys21 and Cys33 (zinc finger motif), augmenting prolyl hydroxylase activity. Depleting endogenous H2S either by hypoxia or by inhibiting CBS via chemical or genetic means reduces persulfidation of PHD2 and inhibits activity, preventing hydroxylation of HIF-1α, resulting in stabilization. Our in vitro findings are further supported by the depletion of CBS in the zebrafish model that exhibits axis defects and abnormal intersegmental vessels. Exogenous H2S supplementation rescues both in vitro and in vivo phenotypes. We have identified the persulfidated residues and defined their functional significance in regulating the activity of PHD2 via point mutations. Thus, the CBS/H2S/PHD2 axis may provide therapeutic opportunities for pathologies associated with HIF-1α dysregulation in chronic diseases.
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Affiliation(s)
- Anindya Dey
- Department of Obstetrics and Gynecology, Peggy and Charles Stephenson Cancer Center, University of Oklahoma Health Science Center, Oklahoma City, OK 73104, USA
| | - Shubhangi Prabhudesai
- Department of Pediatrics, Department of Obstetrics and Gynecology, Children's Research Institute, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Yushan Zhang
- Department of Pathology, Peggy and Charles Stephenson Cancer Center, University of Oklahoma Health Science Center, Oklahoma City, OK 73104, USA
| | - Geeta Rao
- Department of Pathology, Peggy and Charles Stephenson Cancer Center, University of Oklahoma Health Science Center, Oklahoma City, OK 73104, USA
| | - Karthikeyan Thirugnanam
- Department of Pediatrics, Department of Obstetrics and Gynecology, Children's Research Institute, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Md Nazir Hossen
- Department of Pathology, Peggy and Charles Stephenson Cancer Center, University of Oklahoma Health Science Center, Oklahoma City, OK 73104, USA
| | - Shailendra Kumar Dhar Dwivedi
- Department of Obstetrics and Gynecology, Peggy and Charles Stephenson Cancer Center, University of Oklahoma Health Science Center, Oklahoma City, OK 73104, USA
| | - Ramani Ramchandran
- Department of Pediatrics, Department of Obstetrics and Gynecology, Children's Research Institute, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Priyabrata Mukherjee
- Department of Pathology, Peggy and Charles Stephenson Cancer Center, University of Oklahoma Health Science Center, Oklahoma City, OK 73104, USA.
| | - Resham Bhattacharya
- Department of Obstetrics and Gynecology, Peggy and Charles Stephenson Cancer Center, University of Oklahoma Health Science Center, Oklahoma City, OK 73104, USA.
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Abstract
Human survival is dependent upon the continuous delivery of O2 to each cell in the body in sufficient amounts to meet metabolic requirements, primarily for ATP generation by oxidative phosphorylation. Hypoxia-inducible factors (HIFs) regulate the transcription of thousands of genes to balance O2 supply and demand. The HIFs are negatively regulated by O2-dependent hydrox-ylation and ubiquitination by prolyl hydroxylase domain (PHD) proteins and the von Hippel-Lindau (VHL) protein. Germline mutations in the genes encoding VHL, HIF-2α, and PHD2 cause hereditary erythrocytosis, which is characterized by polycythemia and pulmonary hypertension and is caused by increased HIF activity. Evolutionary adaptation to life at high altitude is associated with unique genetic variants in the genes encoding HIF-2α and PHD2 that blunt the erythropoietic and pulmonary vascular responses to hypoxia.
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Affiliation(s)
- Gregg L Semenza
- Departments of Genetic Medicine, Oncology, Pediatrics, Radiation Oncology, Medicine, and Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA;
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Song D, Guan W, Coon LM, Al-Kali A, Oliveira JL, Lee FS. An Erythrocytosis-Associated Mutation in the Zinc Finger of PHD2 Provides Insights into Its Binding of p23. HYPOXIA 2019; 7:81-86. [PMID: 31853455 PMCID: PMC6916684 DOI: 10.2147/hp.s230502] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Accepted: 10/16/2019] [Indexed: 12/30/2022]
Abstract
Background Loss of function mutations in the EGLN1 gene are a cause of erythrocytosis. EGLN1 encodes for prolyl hydroxylase domain protein 2 (PHD2). PHD2 hydroxylates and downregulates hypoxia-inducible factor-2α (HIF-2α), a transcription factor that regulates erythropoiesis. While the large majority of erythrocytosis-associated EGLN1 mutations occur within its catalytic domain, rare mutations reside in its zinc finger. This zinc finger binds a Pro-Xaa-Leu-Glu motif in p23, an HSP90 cochaperone that facilitates hydroxylation of HIF-α, an HSP90 client. Essentially nothing is known about the specific interactions between the PHD2 zinc finger and p23. Results Here, we characterize an erythrocytosis-associated mutation in the zinc finger, K55N, that abolishes interaction with p23. We provide evidence that the affected residue, Lys-55, interacts with Asp-152 of p23. We also present results that indicate that PHD2 Arg-32 interacts with p23 Glu-160. Conclusion These studies not only reinforce the importance of the PHD2 zinc finger in the control of erythropoiesis, but also lead to a model in which a peptide motif in p23 binds in a specific orientation to a predicted groove in the zinc finger of PHD2.
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Affiliation(s)
- Daisheng Song
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Wei Guan
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA.,Department of Ultrasound, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, People's Republic of China.,Hubei Province Key Laboratory of Molecular Imaging, Wuhan 430022, People's Republic of China
| | - Lea M Coon
- Hematopathology, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota, USA
| | - Aref Al-Kali
- Division of Hematology, Department of Internal Medicine, Mayo Clinic, Rochester, Minnesota, USA
| | - Jennifer L Oliveira
- Hematopathology, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota, USA
| | - Frank S Lee
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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12
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Lappin TR, Lee FS. Update on mutations in the HIF: EPO pathway and their role in erythrocytosis. Blood Rev 2019; 37:100590. [PMID: 31350093 DOI: 10.1016/j.blre.2019.100590] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2019] [Revised: 07/02/2019] [Accepted: 07/15/2019] [Indexed: 12/20/2022]
Abstract
Identification of the underlying defects in congenital erythrocytosis has provided mechanistic insights into the regulation of erythropoiesis and oxygen homeostasis. The Hypoxia Inducible Factor (HIF) pathway plays a key role in this regard. In this pathway, an enzyme, Prolyl Hydroxylase Domain protein 2 (PHD2), constitutively prolyl hydroxylates HIF-2α, thereby targeting HIF-2α for degradation by the von Hippel Lindau (VHL) tumor suppressor protein. Under hypoxia, this modification is attenuated, resulting in the stabilization of HIF-2α and transcriptional activation of the erythropoietin (EPO) gene. Circulating EPO then binds to the EPO receptor (EPOR) on red cell progenitors in the bone marrow, leading to expansion of red cell mass. Loss of function mutations in PHD2 and VHL, as well as gain of function mutations in HIF-2α and EPOR, are well established causes of erythrocytosis. Here, we highlight recent developments that show that the study of this condition is still evolving. Specifically, novel mutations have been identified that either change amino acids in the zinc finger domain of PHD2 or alter splicing of the VHL gene. In addition, continued study of HIF-2α mutations has revealed a distinctive genotype-phenotype correlation. Finally, novel mutations have recently been identified in the EPO gene itself. Thus, the cascade of genes that at a molecular level leads to EPO action, namely PHD2 - > HIF2A - > VHL - > EPO - > EPOR, are all mutational targets in congenital erythrocytosis.
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Affiliation(s)
- Terence R Lappin
- Centre for Cancer Research and Cell Biology, Queen's University, Belfast, UK.
| | - Frank S Lee
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
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13
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Congenital and evolutionary modulations of hypoxia sensing and their erythroid phenotype. CURRENT OPINION IN PHYSIOLOGY 2019. [DOI: 10.1016/j.cophys.2018.12.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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Abstract
Hepcidin is the master regulator of iron metabolism. It plays a key role in the regulation of iron transport across the duodenal epithelium, which in turn is dependent on the oxygen-regulated transcription factor hypoxia-inducible factor 2α (HIF-2α). In this issue of the JCI, Schwartz and colleagues show that duodenal HIF-2α is itself regulated by hepcidin, thereby indicating that this transcription factor is not only regulated by oxygen, but also by iron. This work indicates that the crosstalk between liver hepcidin and intestinal HIF-2α plays an important role during iron overload, systemic iron deficiency, and anemia.
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