1
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Khandros E, Blobel GA. Elevating fetal hemoglobin: recently discovered regulators and mechanisms. Blood 2024; 144:845-852. [PMID: 38728575 PMCID: PMC11830979 DOI: 10.1182/blood.2023022190] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Revised: 04/30/2024] [Accepted: 04/30/2024] [Indexed: 05/12/2024] Open
Abstract
ABSTRACT It has been known for over half a century that throughout ontogeny, humans produce different forms of hemoglobin, a tetramer of α- and β-like hemoglobin chains. The switch from fetal to adult hemoglobin occurs around the time of birth when erythropoiesis shifts from the fetal liver to the bone marrow. Naturally, diseases caused by defective adult β-globin genes, such as sickle cell disease and β-thalassemia, manifest themselves as the production of fetal hemoglobin fades. Reversal of this developmental switch has been a major goal to treat these diseases and has been a driving force to understand its underlying molecular biology. Several review articles have illustrated the long and at times arduous paths that led to the discovery of the first transcriptional regulators involved in this process. Here, we survey recent developments spurred by the discovery of CRISPR tools that enabled for the first time high-throughput genetic screens for new molecules that impact the fetal-to-adult hemoglobin switch. Numerous opportunities for therapeutic intervention have thus come to light, offering hope for effective pharmacologic intervention for patients for whom gene therapy is out of reach.
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Affiliation(s)
- Eugene Khandros
- Division of Hematology, Children’s Hospital of Philadelphia, Philadelphia, PA
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Gerd A. Blobel
- Division of Hematology, Children’s Hospital of Philadelphia, Philadelphia, PA
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
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2
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Feng R, Mayuranathan T, Huang P, Doerfler PA, Li Y, Yao Y, Zhang J, Palmer LE, Mayberry K, Christakopoulos GE, Xu P, Li C, Cheng Y, Blobel GA, Simon MC, Weiss MJ. Activation of γ-globin expression by hypoxia-inducible factor 1α. Nature 2022; 610:783-790. [PMID: 36224385 PMCID: PMC9773321 DOI: 10.1038/s41586-022-05312-w] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Accepted: 09/02/2022] [Indexed: 12/24/2022]
Abstract
Around birth, globin expression in human red blood cells (RBCs) shifts from γ-globin to β-globin, which results in fetal haemoglobin (HbF, α2γ2) being gradually replaced by adult haemoglobin (HbA, α2β2)1. This process has motivated the development of innovative approaches to treat sickle cell disease and β-thalassaemia by increasing HbF levels in postnatal RBCs2. Here we provide therapeutically relevant insights into globin gene switching obtained through a CRISPR-Cas9 screen for ubiquitin-proteasome components that regulate HbF expression. In RBC precursors, depletion of the von Hippel-Lindau (VHL) E3 ubiquitin ligase stabilized its ubiquitination target, hypoxia-inducible factor 1α (HIF1α)3,4, to induce γ-globin gene transcription. Mechanistically, HIF1α-HIF1β heterodimers bound cognate DNA elements in BGLT3, a long noncoding RNA gene located 2.7 kb downstream of the tandem γ-globin genes HBG1 and HBG2. This was followed by the recruitment of transcriptional activators, chromatin opening and increased long-range interactions between the γ-globin genes and their upstream enhancer. Similar induction of HbF occurred with hypoxia or with inhibition of prolyl hydroxylase domain enzymes that target HIF1α for ubiquitination by the VHL E3 ubiquitin ligase. Our findings link globin gene regulation with canonical hypoxia adaptation, provide a mechanism for HbF induction during stress erythropoiesis and suggest a new therapeutic approach for β-haemoglobinopathies.
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Affiliation(s)
- Ruopeng Feng
- Department of Hematology, St Jude Children's Research Hospital, Memphis, TN, USA
| | | | - Peng Huang
- Division of Hematology, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Phillip A Doerfler
- Department of Hematology, St Jude Children's Research Hospital, Memphis, TN, USA
| | - Yichao Li
- Department of Hematology, St Jude Children's Research Hospital, Memphis, TN, USA
| | - Yu Yao
- Department of Hematology, St Jude Children's Research Hospital, Memphis, TN, USA
| | - Jingjing Zhang
- Department of Hematology, St Jude Children's Research Hospital, Memphis, TN, USA
| | - Lance E Palmer
- Department of Hematology, St Jude Children's Research Hospital, Memphis, TN, USA
| | - Kalin Mayberry
- Department of Hematology, St Jude Children's Research Hospital, Memphis, TN, USA
| | | | - Peng Xu
- Department of Hematology, St Jude Children's Research Hospital, Memphis, TN, USA
| | - Chunliang Li
- Department of Tumor Cell Biology, St Jude Children's Research Hospital, Memphis, TN, USA
| | - Yong Cheng
- Department of Hematology, St Jude Children's Research Hospital, Memphis, TN, USA
| | - Gerd A Blobel
- Division of Hematology, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - M Celeste Simon
- Abramson Family Cancer Research Institute, Department of Cell and Developmental Biology, University of Pennsylvania, Philadelphia, PA, USA
| | - Mitchell J Weiss
- Department of Hematology, St Jude Children's Research Hospital, Memphis, TN, USA.
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Molokie R, DeSimone J, Lavelle D. Epigenetic regulation of hemoglobin switching in non-human primates. Semin Hematol 2020; 58:10-14. [PMID: 33509438 DOI: 10.1053/j.seminhematol.2020.12.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Revised: 12/01/2020] [Accepted: 12/19/2020] [Indexed: 11/11/2022]
Abstract
Human hemoglobin switching describes the highly regulated, sequential expression of the 5 β-like globin genes (HBE, HBG2, HBG1, HBD and HBB) of the human β-globin gene complex. The sequential activation of these β or β-like globin genes during human development from early embryonic through late fetal ('adult') stages, and during erythroid maturation, occurs in an order corresponding to their 5' to 3' location on chromosome 11. The β-hemoglobinopathies are the most common inherited diseases in humanity, and are diseases of mutated HBB or its altered regulation. Since the other β-like globin genes can potentially substitute for defective HBB, much translational research is directed toward understanding and manipulating sequential activation at the human β-globin gene complex to treat β-hemoglobinopathies. Non-human primates provide a vital contribution to such efforts because of their recapitulation of the developmental/maturational switch in hemoglobin production as observed in humans (mice do not model this switch). Valuable insights into druggable epigenetic forces that mediate the switch have been thereby gained. We review important lessons learned in non-human primates, complemented by other studies, and suggest rational next steps.
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Affiliation(s)
- Robert Molokie
- Sickle Cell Center, Section of Hematology/Oncology, Department of Medicine, University of Illinois at Chicago, and Jesse Brown VA Medical Center, Chicago, IL
| | - Joseph DeSimone
- Sickle Cell Center, Section of Hematology/Oncology, Department of Medicine, University of Illinois at Chicago, and Jesse Brown VA Medical Center, Chicago, IL
| | - Donald Lavelle
- Sickle Cell Center, Section of Hematology/Oncology, Department of Medicine, University of Illinois at Chicago, and Jesse Brown VA Medical Center, Chicago, IL.
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4
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Demirci S, Zeng J, Wu Y, Uchida N, Shen AH, Pellin D, Gamer J, Yapundich M, Drysdale C, Bonanno J, Bonifacino AC, Krouse AE, Linde NS, Engels T, Donahue RE, Haro-Mora JJ, Leonard A, Nassehi T, Luk K, Porter SN, Lazzarotto CR, Tsai SQ, Weiss MJ, Pruett-Miller SM, Wolfe SA, Bauer DE, Tisdale JF. BCL11A enhancer-edited hematopoietic stem cells persist in rhesus monkeys without toxicity. J Clin Invest 2020; 130:6677-6687. [PMID: 32897878 PMCID: PMC7685754 DOI: 10.1172/jci140189] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Accepted: 09/02/2020] [Indexed: 12/11/2022] Open
Abstract
Gene editing of the erythroid-specific BCL11A enhancer in hematopoietic stem and progenitor cells (HSPCs) from patients with sickle cell disease (SCD) induces fetal hemoglobin (HbF) without detectable toxicity, as assessed by mouse xenotransplant. Here, we evaluated autologous engraftment and HbF induction potential of erythroid-specific BCL11A enhancer-edited HSPCs in 4 nonhuman primates. We used a single guide RNA (sgRNA) with identical human and rhesus target sequences to disrupt a GATA1 binding site at the BCL11A +58 erythroid enhancer. Cas9 protein and sgRNA ribonucleoprotein complex (RNP) was electroporated into rhesus HSPCs, followed by autologous infusion after myeloablation. We found that gene edits persisted in peripheral blood (PB) and bone marrow (BM) for up to 101 weeks similarly for BCL11A enhancer- or control locus-targeted (AAVS1-targeted) cells. Biallelic BCL11A enhancer editing resulted in robust γ-globin induction, with the highest levels observed during stress erythropoiesis. Indels were evenly distributed across PB and BM lineages. Off-target edits were not observed. Nonhomologous end-joining repair alleles were enriched in engrafting HSCs. In summary, we found that edited HSCs can persist for at least 101 weeks after transplant and biallelic-edited HSCs provide substantial HbF levels in PB red blood cells, together supporting further clinical translation of this approach.
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Affiliation(s)
- Selami Demirci
- Cellular and Molecular Therapeutics Branch, National Heart Lung and Blood Institute (NHLBI)/National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), NIH, Bethesda, Maryland, USA
| | - Jing Zeng
- Division of Hematology/Oncology, Boston Children’s Hospital, Department of Pediatric Oncology, Dana-Farber Cancer Institute, and Department of Pediatrics, Harvard Stem Cell Institute, Broad Institute, Harvard Medical School, Boston, Massachusetts, USA
| | - Yuxuan Wu
- Division of Hematology/Oncology, Boston Children’s Hospital, Department of Pediatric Oncology, Dana-Farber Cancer Institute, and Department of Pediatrics, Harvard Stem Cell Institute, Broad Institute, Harvard Medical School, Boston, Massachusetts, USA
- Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai, China
| | - Naoya Uchida
- Cellular and Molecular Therapeutics Branch, National Heart Lung and Blood Institute (NHLBI)/National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), NIH, Bethesda, Maryland, USA
| | - Anne H. Shen
- Division of Hematology/Oncology, Boston Children’s Hospital, Department of Pediatric Oncology, Dana-Farber Cancer Institute, and Department of Pediatrics, Harvard Stem Cell Institute, Broad Institute, Harvard Medical School, Boston, Massachusetts, USA
| | - Danilo Pellin
- Gene Therapy Program, Dana-Farber/Boston Children’s Cancer and Blood Disorders Center, Harvard Medical School, Boston, Massachusetts, USA
| | - Jackson Gamer
- Cellular and Molecular Therapeutics Branch, National Heart Lung and Blood Institute (NHLBI)/National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), NIH, Bethesda, Maryland, USA
| | - Morgan Yapundich
- Cellular and Molecular Therapeutics Branch, National Heart Lung and Blood Institute (NHLBI)/National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), NIH, Bethesda, Maryland, USA
| | - Claire Drysdale
- Cellular and Molecular Therapeutics Branch, National Heart Lung and Blood Institute (NHLBI)/National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), NIH, Bethesda, Maryland, USA
| | - Jasmine Bonanno
- Division of Hematology/Oncology, Boston Children’s Hospital, Department of Pediatric Oncology, Dana-Farber Cancer Institute, and Department of Pediatrics, Harvard Stem Cell Institute, Broad Institute, Harvard Medical School, Boston, Massachusetts, USA
| | | | - Allen E. Krouse
- Translational Stem Cell Biology Branch, NHLBI, NIH, Bethesda, Maryland, USA
| | - Nathaniel S. Linde
- Translational Stem Cell Biology Branch, NHLBI, NIH, Bethesda, Maryland, USA
| | - Theresa Engels
- Translational Stem Cell Biology Branch, NHLBI, NIH, Bethesda, Maryland, USA
| | - Robert E. Donahue
- Cellular and Molecular Therapeutics Branch, National Heart Lung and Blood Institute (NHLBI)/National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), NIH, Bethesda, Maryland, USA
| | - Juan J. Haro-Mora
- Cellular and Molecular Therapeutics Branch, National Heart Lung and Blood Institute (NHLBI)/National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), NIH, Bethesda, Maryland, USA
| | - Alexis Leonard
- Cellular and Molecular Therapeutics Branch, National Heart Lung and Blood Institute (NHLBI)/National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), NIH, Bethesda, Maryland, USA
| | - Tina Nassehi
- Cellular and Molecular Therapeutics Branch, National Heart Lung and Blood Institute (NHLBI)/National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), NIH, Bethesda, Maryland, USA
| | - Kevin Luk
- Department of Molecular, Cell and Cancer Biology, Li Weibo Institute for Rare Diseases Research, University of Massachusetts Medical School, Worcester, Massachusetts, USA
| | - Shaina N. Porter
- Department of Cell and Molecular Biology, Center for Advanced Genome Engineering, and
| | - Cicera R. Lazzarotto
- Department of Hematology, St. Jude Children’s Research Hospital, Memphis, Tennessee, USA
| | - Shengdar Q. Tsai
- Department of Hematology, St. Jude Children’s Research Hospital, Memphis, Tennessee, USA
| | - Mitchell J. Weiss
- Department of Hematology, St. Jude Children’s Research Hospital, Memphis, Tennessee, USA
| | | | - Scot A. Wolfe
- Department of Molecular, Cell and Cancer Biology, Li Weibo Institute for Rare Diseases Research, University of Massachusetts Medical School, Worcester, Massachusetts, USA
| | - Daniel E. Bauer
- Division of Hematology/Oncology, Boston Children’s Hospital, Department of Pediatric Oncology, Dana-Farber Cancer Institute, and Department of Pediatrics, Harvard Stem Cell Institute, Broad Institute, Harvard Medical School, Boston, Massachusetts, USA
| | - John F. Tisdale
- Cellular and Molecular Therapeutics Branch, National Heart Lung and Blood Institute (NHLBI)/National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), NIH, Bethesda, Maryland, USA
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5
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Steinberg MH. Fetal Hemoglobin in Sickle Hemoglobinopathies: High HbF Genotypes and Phenotypes. J Clin Med 2020; 9:jcm9113782. [PMID: 33238542 PMCID: PMC7700170 DOI: 10.3390/jcm9113782] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 11/17/2020] [Accepted: 11/19/2020] [Indexed: 12/30/2022] Open
Abstract
Fetal hemoglobin (HbF) usually consists of 4 to 10% of total hemoglobin in adults of African descent with sickle cell anemia. Rarely, their HbF levels reach more than 30%. High HbF levels are sometimes a result of β-globin gene deletions or point mutations in the promoters of the HbF genes. Collectively, the phenotype caused by these mutations is called hereditary persistence of fetal hemoglobin, or HPFH. The pancellularity of HbF associated with these mutations inhibits sickle hemoglobin polymerization in most sickle erythrocytes so that these patients usually have inconsequential hemolysis and few, if any, vasoocclusive complications. Unusually high HbF can also be associated with variants of the major repressors of the HbF genes, BCL11A and MYB. Perhaps most often, we lack an explanation for very high HbF levels in sickle cell anemia.
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Affiliation(s)
- Martin H Steinberg
- Department of Medicine, Division of Hematology/Oncology, Center of Excellence for Sickle Cell Disease, Center for Regenerative Medicine, Genome Science Institute, Boston University School of Medicine and Boston Medical Center, 72 E. Concord St., Boston, MA 02118, USA
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6
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Papayannopoulou T. Control of fetal globin expression in man: new opportunities to challenge past discoveries. Exp Hematol 2020; 92:43-50. [PMID: 32976950 DOI: 10.1016/j.exphem.2020.09.195] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Revised: 09/18/2020] [Accepted: 09/19/2020] [Indexed: 01/01/2023]
Abstract
Decades-old findings supporting origin of F cells in adult life from adult-type progenitors and the in vitro and in vivo enhancement of fetal globin under stress conditions have been juxtaposed against recent mechanistic underpinnings. An updated molecular interrogation did not debunk prior conclusions on the origin of F cells. Although fetal globin reactivation by widely diverse approaches in vitro and in response to anemic stresses in vivo is a work in progress, accumulating evidence converges toward an integrated stress response pathway. The newly uncovered developmental regulators of globin gene switching not only have provided answers to the long-awaited quest of transregulation of switching, they are also reaching a clinical threshold. Although the effect of fetal globin silencers has been robustly validated in adult cells, the response of cells at earlier developmental stages has been unclear and inadequately studied.
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7
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Paulson RF, Hariharan S, Little JA. Stress erythropoiesis: definitions and models for its study. Exp Hematol 2020; 89:43-54.e2. [PMID: 32750404 DOI: 10.1016/j.exphem.2020.07.011] [Citation(s) in RCA: 67] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Revised: 07/28/2020] [Accepted: 07/30/2020] [Indexed: 12/12/2022]
Abstract
Steady-state erythropoiesis generates new erythrocytes at a constant rate, and it has enormous productive capacity. This production is balanced by the removal of senescent erythrocytes by macrophages in the spleen and liver. Erythroid homeostasis is highly regulated to maintain sufficient erythrocytes for efficient oxygen delivery to the tissues, while avoiding viscosity problems associated with overproduction. However, there are times when this constant production of erythrocytes is inhibited or is inadequate; at these times, erythroid output is increased to compensate for the loss of production. In some cases, increased steady-state erythropoiesis can offset the loss of erythrocytes but, in response to inflammation caused by infection or tissue damage, steady-state erythropoiesis is inhibited. To maintain homeostasis under these conditions, an alternative stress erythropoiesis pathway is activated. Emerging data suggest that the bone morphogenetic protein 4 (BMP4)-dependent stress erythropoiesis pathway is integrated into the inflammatory response and generates a bolus of new erythrocytes that maintain homeostasis until steady-state erythropoiesis can resume. In this perspective, we define the mechanisms that generate new erythrocytes when steady-state erythropoiesis is impaired and discuss experimental models to study human stress erythropoiesis.
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Affiliation(s)
- Robert F Paulson
- Center for Molecular Immunology and Infectious Disease and the Department of Veterinary and Biomedical Sciences, Penn State University, University Park, PA; Intercollege Graduate Program in Genetics, Penn State University, University Park, PA.
| | - Sneha Hariharan
- Intercollege Graduate Program in Genetics, Penn State University, University Park, PA
| | - Jane A Little
- Department of Medicine, University of North Carolina Comprehensive Sickle Cell Disease Program, Chapel Hill, NC
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Theodorou A, Phylactides M, Katsantoni E, Vougas K, Garbis SD, Fanis P, Sitarou M, Thein SL, Kleanthous M. Proteomic Studies for the Investigation of γ-Globin Induction by Decitabine in Human Primary Erythroid Progenitor Cultures. J Clin Med 2020; 9:jcm9010134. [PMID: 31947809 PMCID: PMC7019605 DOI: 10.3390/jcm9010134] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Revised: 12/17/2019] [Accepted: 12/26/2019] [Indexed: 11/16/2022] Open
Abstract
Reactivation of γ-globin is considered a promising approach for the treatment of β-thalassemia and sickle cell disease. Therapeutic induction of γ-globin expression, however, is fraught with lack of suitable therapeutic targets. The aim of this study was to investigate the effects that treatment with decitabine has on the proteome of human primary erythroid cells from healthy and thalassemic volunteers, as a means of identifying new potential pharmacological targets. Decitabine is a known γ-globin inducer, which is not, however, safe enough for clinical use. A proteomic approach utilizing isobaric tags for relative and absolute quantitation (iTRAQ) analysis, in combination with high-pH reverse phase peptide fractionation followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS), was employed to investigate the effects of decitabine treatment. Bioinformatics analysis making use of the Database for Annotation, Visualization and Integrated Discovery (DAVID) was employed for functional annotation of the 192 differentially expressed proteins identified. The data are available via ProteomeXchange with identifier PXD006889. The proteins fall into various biological pathways, such as the NF-κB signaling pathway, and into many functional categories including regulation of cell proliferation, transcription factor and DNA binding, protein stabilization, chromatin modification and organization, and oxidative stress proteins.
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Affiliation(s)
- Andria Theodorou
- Molecular Genetics Thalassaemic Department, Cyprus Institute of Neurology and Genetics, Nicosia 2371, Cyprus
| | - Marios Phylactides
- Molecular Genetics Thalassaemic Department, Cyprus Institute of Neurology and Genetics, Nicosia 2371, Cyprus
- Correspondence: ; Tel.: +357-22-392657
| | - Eleni Katsantoni
- Basic Research Center, Biomedical Research Foundation, Academy of Athens, 11527 Athens, Greece
| | - Kostas Vougas
- Basic Research Center, Biomedical Research Foundation, Academy of Athens, 11527 Athens, Greece
| | - Spyros D. Garbis
- Basic Research Center, Biomedical Research Foundation, Academy of Athens, 11527 Athens, Greece
- Division for Cancer Sciences, Southampton General Hospital, University of Southampton, Southampton SO16 6YD, UK
- Centre for Proteomics Research, Institute for Life Sciences, Highfield Campus, University of Southampton, Southampton SO17 1BJ, UK
| | - Pavlos Fanis
- Molecular Genetics Thalassaemic Department, Cyprus Institute of Neurology and Genetics, Nicosia 2371, Cyprus
- Molecular Genetics Function and Therapy Department, Cyprus Institute of Neurology and Genetics, Nicosia 2371, Cyprus
| | - Maria Sitarou
- Thalassaemia Centre, Larnaca General Hospital, Larnaca 6043, Cyprus
| | - Swee Lay Thein
- Sickle cell branch, National Heart, Lung and Blood Institute, The National Institutes of Health, Bethesda, MD 20814, USA
| | - Marina Kleanthous
- Molecular Genetics Thalassaemic Department, Cyprus Institute of Neurology and Genetics, Nicosia 2371, Cyprus
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Saunthararajah Y. Targeting sickle cell disease root-cause pathophysiology with small molecules. Haematologica 2019; 104:1720-1730. [PMID: 31399526 PMCID: PMC6717594 DOI: 10.3324/haematol.2018.207530] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Accepted: 07/09/2019] [Indexed: 12/28/2022] Open
Abstract
The complex, frequently devastating, multi-organ pathophysiology of sickle cell disease has a single root cause: polymerization of deoxygenated sickle hemoglobin. A logical approach to disease modification is, therefore, to interdict this root cause. Ideally, such interdiction would utilize small molecules that are practical and accessible for worldwide application. Two types of such small molecule strategies are actively being evaluated in the clinic. The first strategy intends to shift red blood cell precursor hemoglobin manufacturing away from sickle hemoglobin and towards fetal hemoglobin, which inhibits sickle hemoglobin polymerization by a number of mechanisms. The second strategy intends to chemically modify sickle hemoglobin directly in order to inhibit its polymerization. Important lessons have been learnt from the pre-clinical and clinical evaluations to date. Open questions remain, but this review summarizes the valuable experience and knowledge already gained, which can guide ongoing and future efforts for molecular mechanism-based, practical and accessible disease modification of sickle cell disease.
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Affiliation(s)
- Yogen Saunthararajah
- Department of Hematology and Oncology, Taussig Cancer Institute, Cleveland Clinic, Cleveland, OH, USA
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10
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Lavelle D, Engel JD, Saunthararajah Y. Fetal Hemoglobin Induction by Epigenetic Drugs. Semin Hematol 2018; 55:60-67. [PMID: 29958562 DOI: 10.1053/j.seminhematol.2018.04.008] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Accepted: 04/13/2018] [Indexed: 12/11/2022]
Abstract
Fetal hemoglobin (HbF) inhibits the root cause of sickle pathophysiology, sickle hemoglobin polymerization. Individuals who naturally express high levels of HbF beyond infancy thus receive some protection from sickle complications. To mimic this natural genetic experiment using drugs, one guiding observation was that HbF is increased during recovery of bone marrow from extreme stress. This led to evaluation and approval of the cytotoxic (cell killing) drug hydroxyurea to treat sickle cell disease. Cytotoxic approaches are limited in potency and sustainability, however, since they require hematopoietic reserves sufficient to repeatedly mount recoveries from stress that destroys their counterparts, and such reserves are finite. HbF induction even by stress ultimately involves chromatin remodeling of the gene for HbF (HBG), therefore, a logical alternative approach is to directly inhibit epigenetic enzymes that repress HBG-implicated enzymes include DNA methyltransferase 1, histone deacetylases, lysine demethylase 1, protein arginine methyltransferase 5, euchromatic histone lysine methyltransferase 2 and chromodomain helicase DNA-binding protein 4. Clinical proof-of-principle that this alternative, noncytotoxic approach can generate substantial HbF and total hemoglobin increases has already been generated. Thus, with continued careful attention to fundamental biological and pharmacologic considerations (reviewed herein), there is potential that rational, molecular-targeted, safe and highly potent disease-modifying therapy can be realized for patients with sickle cell disease, with the accessibility and cost-effective properties needed for world-wide effect.
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Affiliation(s)
- Donald Lavelle
- Department of Medicine, University of Illinois Hospital and Health Sciences System, Chicago, IL; Department of Medicine, Jesse Brown VA Medical Center, Chicago, IL
| | | | - Yogen Saunthararajah
- Department of Hematology and Oncology, Taussig Cancer Institute, Cleveland Clinic, Cleveland, OH.
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11
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Humbert O, Peterson CW, Norgaard ZK, Radtke S, Kiem HP. A Nonhuman Primate Transplantation Model to Evaluate Hematopoietic Stem Cell Gene Editing Strategies for β-Hemoglobinopathies. MOLECULAR THERAPY-METHODS & CLINICAL DEVELOPMENT 2017; 8:75-86. [PMID: 29276718 PMCID: PMC5738324 DOI: 10.1016/j.omtm.2017.11.005] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Accepted: 11/14/2017] [Indexed: 12/19/2022]
Abstract
Reactivation of fetal hemoglobin (HbF) is a promising approach for the treatment of β-hemoglobinopathies and the targeting of genes involved in HbF regulation is under intensive investigation. Here, we established a nonhuman primate (NHP) transplantation model to evaluate hematopoietic stem cell (HSC)-based gene editing strategies aimed at reactivating HbF. We first characterized the transient HbF induction to autologous HSC transplantation in pigtailed macaques, which was comparable in duration and amplitude to that of human patients. After validating function of the HbF repressor BCL11A in NHPs, we transplanted a pigtailed macaque with CD34+ cells electroporated with TALE nuclease mRNA targeting the BCL11A coding sequence. In vivo gene editing levels were low, but some BCL11A deletions were detected as late as 200 days post-transplantation. HbF production, as determined by F-cell staining and γ-globin expression, was slightly increased in this animal as compared to transplant controls. We also provided proof-of-concept results for the selection of edited NHP CD34+ cells in culture following integration of the P140K/MGMT cassette at the BCL11A locus. In summary, the NHP model described here will allow the testing of novel therapeutic approaches for hemoglobinopathies and should facilitate clinical translation.
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Affiliation(s)
- Olivier Humbert
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | | | - Zachary K. Norgaard
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | - Stefan Radtke
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | - Hans-Peter Kiem
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
- Department of Medicine, University of Washington, Seattle, WA, USA
- Department of Pathology, University of Washington, Seattle, WA, USA
- Corresponding author: Hans-Peter Kiem, Fred Hutchinson Cancer Research Center, P.O. Box 19024, Mail Stop D1-100, Seattle, WA 98109-1024, USA.
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Molokie R, Lavelle D, Gowhari M, Pacini M, Krauz L, Hassan J, Ibanez V, Ruiz MA, Ng KP, Woost P, Radivoyevitch T, Pacelli D, Fada S, Rump M, Hsieh M, Tisdale JF, Jacobberger J, Phelps M, Engel JD, Saraf S, Hsu LL, Gordeuk V, DeSimone J, Saunthararajah Y. Oral tetrahydrouridine and decitabine for non-cytotoxic epigenetic gene regulation in sickle cell disease: A randomized phase 1 study. PLoS Med 2017; 14:e1002382. [PMID: 28880867 PMCID: PMC5589090 DOI: 10.1371/journal.pmed.1002382] [Citation(s) in RCA: 99] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/03/2017] [Accepted: 08/03/2017] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Sickle cell disease (SCD), a congenital hemolytic anemia that exacts terrible global morbidity and mortality, is driven by polymerization of mutated sickle hemoglobin (HbS) in red blood cells (RBCs). Fetal hemoglobin (HbF) interferes with this polymerization, but HbF is epigenetically silenced from infancy onward by DNA methyltransferase 1 (DNMT1). METHODS AND FINDINGS To pharmacologically re-induce HbF by DNMT1 inhibition, this first-in-human clinical trial (NCT01685515) combined 2 small molecules-decitabine to deplete DNMT1 and tetrahydrouridine (THU) to inhibit cytidine deaminase (CDA), the enzyme that otherwise rapidly deaminates/inactivates decitabine, severely limiting its half-life, tissue distribution, and oral bioavailability. Oral decitabine doses, administered after oral THU 10 mg/kg, were escalated from a very low starting level (0.01, 0.02, 0.04, 0.08, or 0.16 mg/kg) to identify minimal doses active in depleting DNMT1 without cytotoxicity. Patients were SCD adults at risk of early death despite standard-of-care, randomized 3:2 to THU-decitabine versus placebo in 5 cohorts of 5 patients treated 2X/week for 8 weeks, with 4 weeks of follow-up. The primary endpoint was ≥ grade 3 non-hematologic toxicity. This endpoint was not triggered, and adverse events (AEs) were not significantly different in THU-decitabine-versus placebo-treated patients. At the decitabine 0.16 mg/kg dose, plasma concentrations peaked at approximately 50 nM (Cmax) and remained elevated for several hours. This dose decreased DNMT1 protein in peripheral blood mononuclear cells by >75% and repetitive element CpG methylation by approximately 10%, and increased HbF by 4%-9% (P < 0.001), doubling fetal hemoglobin-enriched red blood cells (F-cells) up to approximately 80% of total RBCs. Total hemoglobin increased by 1.2-1.9 g/dL (P = 0.01) as reticulocytes simultaneously decreased; that is, better quality and efficiency of HbF-enriched erythropoiesis elevated hemoglobin using fewer reticulocytes. Also indicating better RBC quality, biomarkers of hemolysis, thrombophilia, and inflammation (LDH, bilirubin, D-dimer, C-reactive protein [CRP]) improved. As expected with non-cytotoxic DNMT1-depletion, platelets increased and neutrophils concurrently decreased, but not to an extent requiring treatment holds. As an early phase study, limitations include small patient numbers at each dose level and narrow capacity to evaluate clinical benefits. CONCLUSION Administration of oral THU-decitabine to patients with SCD was safe in this study and, by targeting DNMT1, upregulated HbF in RBCs. Further studies should investigate clinical benefits and potential harms not identified to date. TRIAL REGISTRATION ClinicalTrials.gov, NCT01685515.
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Affiliation(s)
- Robert Molokie
- Department of Medicine, University of Illinois Hospital and Health Sciences System, Chicago, Illinois, United States of America
- Jesse Brown VA Medical Center, Chicago, Illinois, United States of America
| | - Donald Lavelle
- Department of Medicine, University of Illinois Hospital and Health Sciences System, Chicago, Illinois, United States of America
- Jesse Brown VA Medical Center, Chicago, Illinois, United States of America
| | - Michel Gowhari
- Department of Medicine, University of Illinois Hospital and Health Sciences System, Chicago, Illinois, United States of America
| | - Michael Pacini
- Department of Medicine, University of Illinois Hospital and Health Sciences System, Chicago, Illinois, United States of America
| | - Lani Krauz
- Department of Medicine, University of Illinois Hospital and Health Sciences System, Chicago, Illinois, United States of America
| | - Johara Hassan
- Department of Medicine, University of Illinois Hospital and Health Sciences System, Chicago, Illinois, United States of America
| | - Vinzon Ibanez
- Jesse Brown VA Medical Center, Chicago, Illinois, United States of America
| | - Maria A. Ruiz
- Jesse Brown VA Medical Center, Chicago, Illinois, United States of America
| | - Kwok Peng Ng
- Translational Hematology and Oncology Research, Taussig Cancer Institute, Cleveland Clinic, Cleveland, Ohio, United States of America
| | - Philip Woost
- Case Comprehensive Cancer Center, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Tomas Radivoyevitch
- Department of Quantitative Health Sciences, Cleveland Clinic, Cleveland, Ohio, United States of America
| | - Daisy Pacelli
- Department of Medicine, University of Illinois Hospital and Health Sciences System, Chicago, Illinois, United States of America
| | - Sherry Fada
- Department of Hematology and Oncology, Taussig Cancer Institute, Cleveland Clinic, Cleveland, Ohio, United States of America
| | - Matthew Rump
- Department of Hematology and Oncology, Taussig Cancer Institute, Cleveland Clinic, Cleveland, Ohio, United States of America
| | - Matthew Hsieh
- Molecular and Clinical Hematology Section, National Institutes of Health, Bethesda, Maryland, United States of America
| | - John F. Tisdale
- Molecular and Clinical Hematology Section, National Institutes of Health, Bethesda, Maryland, United States of America
| | - James Jacobberger
- Case Comprehensive Cancer Center, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Mitch Phelps
- College of Pharmacy, The Ohio State University, Columbus, Ohio, United States of America
| | - James Douglas Engel
- Cell and Developmental Biology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Santhosh Saraf
- Department of Medicine, University of Illinois Hospital and Health Sciences System, Chicago, Illinois, United States of America
| | - Lewis L. Hsu
- Department of Medicine, University of Illinois Hospital and Health Sciences System, Chicago, Illinois, United States of America
| | - Victor Gordeuk
- Department of Medicine, University of Illinois Hospital and Health Sciences System, Chicago, Illinois, United States of America
| | - Joseph DeSimone
- Department of Medicine, University of Illinois Hospital and Health Sciences System, Chicago, Illinois, United States of America
| | - Yogen Saunthararajah
- Translational Hematology and Oncology Research, Taussig Cancer Institute, Cleveland Clinic, Cleveland, Ohio, United States of America
- Department of Hematology and Oncology, Taussig Cancer Institute, Cleveland Clinic, Cleveland, Ohio, United States of America
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Nkya S, Mgaya J, Urio F, Makubi A, Thein SL, Menzel S, Cox SE, Newton CR, Kirkham FJ, Mmbando BP, Makani J. Fetal Hemoglobin is Associated with Peripheral Oxygen Saturation in Sickle Cell Disease in Tanzania. EBioMedicine 2017; 23:146-149. [PMID: 28844412 PMCID: PMC5605324 DOI: 10.1016/j.ebiom.2017.08.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Revised: 07/31/2017] [Accepted: 08/05/2017] [Indexed: 11/10/2022] Open
Abstract
Fetal hemoglobin (HbF) and peripheral hemoglobin oxygen saturation (SpO2) both predict clinical severity in sickle cell disease (SCD), while reticulocytosis is associated with vasculopathy, but there are few data on mechanisms. HbF, SpO2 and routine clinical and laboratory measures were available in a Tanzanian cohort of 1175 SCD individuals aged ≥ 5 years and the association with SpO2 (as response variable transformed to a Poisson distribution) was assessed by negative binomial model with age and sex as covariates. Increase in HbF was associated with increased SpO2 (rate ratio, RR = 1.19; 95% confidence intervals [CI] 1.04, 1.37 per natural log unit of HbF; p = 0.0004). In univariable analysis, SpO2 was inversely associated with age, reticulocyte count, and log (total bilirubin) and directly with pulse, SBP, hemoglobin, and log(HbF). In multivariable regression log(HbF) (RR 1.191; 95%CI 1.04, 1.37; p = 0.013), pulse (RR 1.01; 95%CI 1.00, 1.01; p = 0.026), SBP (RR 1.008; 95%CI 1.00, 1.02; p = 0.014), and hemoglobin (1.120; 95%CI 1.05, 1.19; p = 0.001) were positively and independently associated with SpO2 while reticulocyte count (RR 0.985; 95%CI 0.97, 0.99; p = 0.019) was independently inversely associated with SpO2. In SCD, improving SpO2, in part through cardiovascular compensation and associated with reduced reticulocytosis, may be a mechanism by which HbF reduces disease severity. Fetal hemoglobin may moderate sickle cell disease through increased oxygen saturation. Low oxygen saturation is associated with reticulocytosis which might moderate cerebral vasculopathy and stroke risk. Higher pulse rate and systolic blood pressure in those with higher SpO2 suggests cardiovascular compensation for low SpO2.
Fetal hemoglobin (HbF) is normally synthesized during intrauterine life and it starts to decline before birth being replaced by adult hemoglobin (HbA). However some individuals continue to synthesize HbF to adulthood and are relatively protected from severe sickle cell disease. The mechanism of HbF protection in SCD has not been entirely established. This study reports a positive association between HbF and oxygen saturation (SpO2). Higher SpO2 is associated with decreased reticulocytes but increased pulse rate and systolic blood pressure, suggesting SpO2 is maintained in part through cardiovascular compensation. Increasing HbF may reduce disease severity partly through increasing SpO2.
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Affiliation(s)
- Siana Nkya
- Sickle Cell Programme, Muhimbili University of Health and Allied Sciences, Dar-es-Salaam, Tanzania; Dar-es-Salaam University College of Education, Dar-es-Salaam, Tanzania.
| | - Josephine Mgaya
- Sickle Cell Programme, Muhimbili University of Health and Allied Sciences, Dar-es-Salaam, Tanzania
| | - Florence Urio
- Sickle Cell Programme, Muhimbili University of Health and Allied Sciences, Dar-es-Salaam, Tanzania
| | - Abel Makubi
- Sickle Cell Programme, Muhimbili University of Health and Allied Sciences, Dar-es-Salaam, Tanzania
| | - Swee Lay Thein
- King's College London, Molecular Haematology, Division of Cancer Studies, UK; Sickle Cell Branch, National Heart, Lung and Blood Institute, The National Institutes of Health, USA
| | - Stephan Menzel
- King's College London, Molecular Haematology, Division of Cancer Studies, UK
| | - Sharon E Cox
- Sickle Cell Programme, Muhimbili University of Health and Allied Sciences, Dar-es-Salaam, Tanzania; Graduate School of Tropical Medicine & Global Health, Nagasaki University, Nagasaki, Japan; Faculty of Epidemiology & Population Health, London School of Hygiene & Tropical Medicine, London, UK
| | - Charles R Newton
- Sickle Cell Programme, Muhimbili University of Health and Allied Sciences, Dar-es-Salaam, Tanzania; Nuffield Department of Medicine, University of Oxford, UK
| | - Fenella J Kirkham
- UCL Great Oromnd Street Institute of Child Health, London, UK; Clinical and Experimental Sciences, University of Southampton, UK; Southampton Children's Hospital, UK
| | - Bruno P Mmbando
- Sickle Cell Programme, Muhimbili University of Health and Allied Sciences, Dar-es-Salaam, Tanzania; National Institute for Medical Research, Tanga Centre, Tanga, Tanzania
| | - Julie Makani
- Sickle Cell Programme, Muhimbili University of Health and Allied Sciences, Dar-es-Salaam, Tanzania; Nuffield Department of Medicine, University of Oxford, UK
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Altinoz MA, Ince B. Hemoglobins emerging roles in mental disorders. Metabolical, genetical and immunological aspects. Int J Dev Neurosci 2017; 61:73-85. [PMID: 28694195 DOI: 10.1016/j.ijdevneu.2017.06.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Revised: 06/23/2017] [Accepted: 06/26/2017] [Indexed: 12/13/2022] Open
Abstract
Hemoglobin (Hb) expression in the central nervous system is recently shown. Cooccurences of mental disorders (mainly bipolar disorder (BD) and tic disorders) with β- or α-thalassemia trait or erythrocytosis were witnessed, which may be due to peripheral or central hypoxia/hyperoxia or haplotypal gene interactions. β-Globin genes reside at 11p15.5 close to tyrosine hydroxylase, dopamine receptor DRD4 and Brain Derived Neurotrophic Factor, which involve in psychiatric diseases. α-Globin genes reside at 16p13.3 which associates with BD, tic disorders, ATR-16 Syndrome and Rubinstein Taybi Syndrome (RTS). CREB-Binding Protein (CEBBP)-gene is mutated in RTS, which commonly associates with mood disorders. 16p13.3 region also contains GRIN2A gene encoding N-methyl-d-aspartate receptor-2A and SSTR5 (Somatostatin Receptor-5), again involving in mental disorders. We demonstrated a protective role of minor HbA2 against post-partum episodes in BD and association of higher minor HbF (fetal hemoglobin) levels with family history of psychosis in a BD-patient cohort. HbA2 increases in cardiac ischemia and in mountain dwellers indicating its likely protection against ischemia/hypoxia. HMGIY, a repressive transcription factor of δ-globin chain of HbA2 is increased in lymphocytes of schizophrenics. In autism, deletional mutations were found in BCL11A gene, which cause persistence of HbF at high levels in adulthood. Also, certain polymorphisms in BCL11A strongly associate with schizophrenia. Further, many drugs from anabolic steroids to antimalarial agents elevate HbF and may cause mania. We ascribe a protective role to HbA2 and a maladaptive detrimental role to HbF in psychopathology. We believe that future studies on hemoglobins may pave to discover novel pathogenesis mechanisms in mental disorders.
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Affiliation(s)
| | - Bahri Ince
- Department of Psychiatry, Bakirkoy Education and Research Hospital for Psychiatry, Turkey
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SENP1, but not fetal hemoglobin, differentiates Andean highlanders with chronic mountain sickness from healthy individuals among Andean highlanders. Exp Hematol 2016; 44:483-490.e2. [PMID: 26952840 DOI: 10.1016/j.exphem.2016.02.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Revised: 02/16/2016] [Accepted: 02/17/2016] [Indexed: 01/25/2023]
Abstract
Chronic mountain sickness (CMS) results from chronic hypoxia. It is unclear why certain highlanders develop CMS. We hypothesized that modest increases in fetal hemoglobin (HbF) are associated with lower CMS severity. In this cross-sectional study, we found that HbF levels were normal (median = 0.4%) in all 153 adult Andean natives in Cerro de Pasco, Peru. Compared with healthy adults, the borderline elevated hemoglobin group frequently had symptoms (headaches, tinnitus, cyanosis, dilatation of veins) of CMS. Although the mean hemoglobin level differed between the healthy (17.1 g/dL) and CMS (22.3 g/dL) groups, mean plasma erythropoietin (EPO) levels were similar (healthy, 17.7 mIU/mL; CMS, 12.02 mIU/mL). Sanger sequencing determined that single-nucleotide polymorphisms in endothelial PAS domain 1 (EPAS1) and egl nine homolog 1 (EGLN1), associated with lower hemoglobin in Tibetans, were not identified in Andeans. Sanger sequencing of sentrin-specific protease 1 (SENP1) and acidic nuclear phosphoprotein 32 family, member D (ANP32D), in healthy and CMS individuals revealed that non-G/G genotypes were associated with higher CMS scores. No JAK2 V617F mutation was detected in CMS individuals. Thus, HbF and other classic erythropoietic parameters did not differ between healthy and CMS individuals. However, the non-G/G genotypes of SENP1 appeared to differentiate individuals with CMS from healthy Andean highlanders.
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Avni R, Golani O, Akselrod-Ballin A, Cohen Y, Biton I, Garbow JR, Neeman M. MR Imaging-derived Oxygen-Hemoglobin Dissociation Curves and Fetal-Placental Oxygen-Hemoglobin Affinities. Radiology 2016; 280:68-77. [PMID: 26780539 PMCID: PMC4942994 DOI: 10.1148/radiol.2015150721] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
The authors of this study present a noninvasive approach for obtaining MR imaging–based oxygen-hemoglobin dissociation curves and for deriving oxygen tension values at which hemoglobin is 50% saturated and maps for the placenta and fetus in pregnant mice. Purpose To generate magnetic resonance (MR) imaging–derived, oxygen-hemoglobin dissociation curves and to map fetal-placental oxygen-hemoglobin affinity in pregnant mice noninvasively by combining blood oxygen level–dependent (BOLD) T2* and oxygen-weighted T1 contrast mechanisms under different respiration challenges. Materials and Methods All procedures were approved by the Weizmann Institutional Animal Care and Use Committee. Pregnant mice were analyzed with MR imaging at 9.4 T on embryonic days 14.5 (eight dams and 58 fetuses; imprinting control region ICR strain) and 17.5 (21 dams and 158 fetuses) under respiration challenges ranging from hyperoxia to hypoxia (10 levels of oxygenation, 100%–10%; total imaging time, 100 minutes). A shorter protocol with normoxia to hyperoxia was also performed (five levels of oxygenation, 20%–100%; total imaging time, 60 minutes). Fast spin-echo anatomic images were obtained, followed by sequential acquisition of three-dimensional gradient-echo T2*- and T1-weighted images. Automated registration was applied to align regions of interest of the entire placenta, fetal liver, and maternal liver. Results were compared by using a two-tailed unpaired Student t test. R1 and R2* values were derived for each tissue. MR imaging–based oxygen-hemoglobin dissociation curves were constructed by nonlinear least square fitting of 1 minus the change in R2*divided by R2*at baseline as a function of R1 to a sigmoid-shaped curve. The apparent P50 (oxygen tension at which hemoglobin is 50% saturated) value was derived from the curves, calculated as the R1 scaled value (x) at which the change in R2* divided by R2*at baseline scaled (y) equals 0.5. Results The apparent P50 values were significantly lower in fetal liver than in maternal liver for both gestation stages (day 14.5: 21% ± 5 [P = .04] and day 17.5: 41% ± 7 [P < .0001]). The placenta showed a reduction of 18% ± 4 in mean apparent P50 values from day 14.5 to day 17.5 (P = .003). Reproduction of the MR imaging–based oxygen-hemoglobin dissociation curves with a shorter protocol that excluded the hypoxic periods was demonstrated. Conclusion MR imaging–based oxygen-hemoglobin dissociation curves and oxygen-hemoglobin affinity information were derived for pregnant mice by using 9.4-T MR imaging, which suggests a potential to overcome the need for direct sampling of fetal or maternal blood. Online supplemental material is available for this article.
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Affiliation(s)
- Reut Avni
- From the Departments of Biological Regulation (R.A., A.A.B., Y.C., M.N.), Biological Services (O.G.), and Veterinary Resources (I.B.), Weizmann Institute of Science, Rehovot 76100, Israel; and Biomedical Magnetic Resonance Laboratory, Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, Mo (J.R.G.)
| | - Ofra Golani
- From the Departments of Biological Regulation (R.A., A.A.B., Y.C., M.N.), Biological Services (O.G.), and Veterinary Resources (I.B.), Weizmann Institute of Science, Rehovot 76100, Israel; and Biomedical Magnetic Resonance Laboratory, Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, Mo (J.R.G.)
| | - Ayelet Akselrod-Ballin
- From the Departments of Biological Regulation (R.A., A.A.B., Y.C., M.N.), Biological Services (O.G.), and Veterinary Resources (I.B.), Weizmann Institute of Science, Rehovot 76100, Israel; and Biomedical Magnetic Resonance Laboratory, Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, Mo (J.R.G.)
| | - Yonni Cohen
- From the Departments of Biological Regulation (R.A., A.A.B., Y.C., M.N.), Biological Services (O.G.), and Veterinary Resources (I.B.), Weizmann Institute of Science, Rehovot 76100, Israel; and Biomedical Magnetic Resonance Laboratory, Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, Mo (J.R.G.)
| | - Inbal Biton
- From the Departments of Biological Regulation (R.A., A.A.B., Y.C., M.N.), Biological Services (O.G.), and Veterinary Resources (I.B.), Weizmann Institute of Science, Rehovot 76100, Israel; and Biomedical Magnetic Resonance Laboratory, Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, Mo (J.R.G.)
| | - Joel R Garbow
- From the Departments of Biological Regulation (R.A., A.A.B., Y.C., M.N.), Biological Services (O.G.), and Veterinary Resources (I.B.), Weizmann Institute of Science, Rehovot 76100, Israel; and Biomedical Magnetic Resonance Laboratory, Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, Mo (J.R.G.)
| | - Michal Neeman
- From the Departments of Biological Regulation (R.A., A.A.B., Y.C., M.N.), Biological Services (O.G.), and Veterinary Resources (I.B.), Weizmann Institute of Science, Rehovot 76100, Israel; and Biomedical Magnetic Resonance Laboratory, Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, Mo (J.R.G.)
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Ginder GD. Epigenetic regulation of fetal globin gene expression in adult erythroid cells. Transl Res 2015; 165:115-25. [PMID: 24880147 PMCID: PMC4227965 DOI: 10.1016/j.trsl.2014.05.002] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Revised: 05/02/2014] [Accepted: 05/05/2014] [Indexed: 10/25/2022]
Abstract
The developmental regulation of globin gene expression has served as an important model for understanding higher eukaryotic transcriptional control mechanisms. During human erythroid development, there is a sequential switch from expression of the embryonic ε-globin gene to the fetal ɣ-globin gene in utero, and postpartum the ɣ-globin gene is silenced, as the β-globin gene becomes the predominantly expressed locus. Because the expression of normally silenced fetal ɣ-type globin genes and resultant production of fetal hemoglobin (HbF) in adult erythroid cells can ameliorate the pathophysiological consequences of both abnormal β-globin chains in sickle cell anemia and deficient β-globin chain production in β-thalassemia, understanding the complex mechanisms of this developmental switch has direct translational clinical relevance. Of particular interest for translational research are the factors that mediate silencing of the ɣ-globin gene in adult stage erythroid cells. In addition to the regulatory roles of transcription factors and their cognate DNA sequence motifs, there has been a growing appreciation of the role of epigenetic signals and their cognate factors in gene regulation, and in particular in gene silencing through chromatin. Much of the information about epigenetic silencing stems from studies of globin gene regulation. As discussed here, the term epigenetics refers to postsynthetic modifications of DNA and chromosomal histone proteins that affect gene expression and can be inherited through somatic cell replication. A full understanding of the molecular mechanisms of epigenetic silencing of HbF expression should facilitate the development of more effective treatment of β-globin chain hemoglobinopathies.
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Affiliation(s)
- Gordon D Ginder
- Virginia Commonwealth University Massey Cancer Center, Richmond, VA, USA.
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Natural Remedies for the Treatment of Beta-Thalassemia and Sickle Cell Anemia-Current Status and Perspectives in Fetal Hemoglobin Reactivation. INTERNATIONAL SCHOLARLY RESEARCH NOTICES 2014; 2014:123257. [PMID: 27350962 PMCID: PMC4897541 DOI: 10.1155/2014/123257] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 04/18/2014] [Revised: 07/21/2014] [Accepted: 07/25/2014] [Indexed: 11/18/2022]
Abstract
For the treatment of β-thalassemia and sickle cell disease (SCD), pharmacological induction of fetal hemoglobin (HbF) production may be a promising approach. To date, numerous studies have been done on identifying the novel HbF-inducing agents and understanding the underlying mechanism for stimulating the HbF production. In this review, we have summarized the identified HbF-inducing agents by far. By examining the action mechanisms of the HbF-inducing agents, various studies have suggested that despite the ability of stimulating HbF production, the chemotherapeutic agents could not be practically applied for treating β-hemoglobinopathies, especially β-thalassemia, due to the their cytotoxicity and growth-inhibitory effect. Owing to this therapeutic obstacle, much effort has been put on identifying new HbF-inducing agents from the natural world with the combination of efficacy, safety, and ease of use. Therefore, this review aims to (i) reveal the novel screening platforms for identifying potential inducers with high efficiency and accuracy and to (ii) summarize the new identified natural remedies for stimulating HbF production. Hopefully, this review can provide a new insight into the current status and future perspectives in fetal hemoglobin reactivation for treating β-thalassaemia and SCD.
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Risso A, Fabbro D, Damante G, Antonutto G. Expression of fetal hemoglobin in adult humans exposed to high altitude hypoxia. Blood Cells Mol Dis 2012; 48:147-53. [PMID: 22260786 DOI: 10.1016/j.bcmd.2011.12.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2011] [Revised: 12/07/2011] [Accepted: 12/12/2011] [Indexed: 12/15/2022]
Abstract
In humans, acute erythroid expansion can lead to maturation of red blood cell (RBC) precursors containing fetal hemoglobin (F red cells). This can occur in patients after recovery from bone marrow transplantation, or in individuals affected by sickle cell or thalassemic syndromes. An accelerated erythroid lineage expansion is also a hallmark of the adaptive response to high altitude hypoxia. To explore the possible effect of this environment on F red cell production, we analyzed RBCs from five subjects during and after 17 days spent at high altitude and investigated the expression of fetal hemoglobin by different methodological approaches. By flow cytometry, we found a moderate increase of circulating F red cells during and after the hypoxia exposure, with respect to control cells analyzed before a stay at high altitude. The increased expression of γ-globin (as the specific subunit contained in F hemoglobin together with α-globin) was further confirmed by immunoblotting of young RBC hemolysates and quantitative RT-PCR of transcripts purified from a reticulocyte-enriched RBC fraction. Thus, in healthy adults the exposure to high altitude hypoxia induces maturation of F red cells at a level higher than under normal condition. The effect appears reduced after return to normoxia.
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Affiliation(s)
- Angela Risso
- Department of Agricultural and Environment Science, University of Udine, Udine, Italy.
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Abstract
PURPOSE OF REVIEW Acute anemic stress induces a physiological response that includes the rapid development of new erythrocytes. This process is referred to as stress erythropoiesis, which is distinct from steady state erythropoiesis. Much of what we know about stress erythropoiesis comes from the analysis of murine models. In this review, we will discuss our current understanding of the mechanisms that regulate stress erythropoiesis in mice and discuss outstanding questions in the field. RECENT FINDINGS Stress erythropoiesis occurs in the murine spleen, fetal liver and adult liver. The signals that regulate this process are Hedgehog, bone morphogenetic protein 4 (BMP4), stem cell factor and hypoxia. Recent findings show that stress erythropoiesis utilizes a population of erythroid-restricted self-renewing stress progenitors. Although the BMP4-dependent stress erythropoiesis pathway was first characterized during the recovery from acute anemia, analysis of a mouse model of chronic anemia demonstrated that activation of the BMP4-dependent stress erythropoiesis pathway provides compensatory erythropoiesis in response to chronic anemia as well. SUMMARY The BMP4-dependent stress erythropoiesis pathway plays a key role in the recovery from acute anemia and new data show that this pathway compensates for ineffective steady state erythropoiesis in a murine model of chronic anemia. The identification of a self-renewing population of stress erythroid progenitors in mice suggests that therapeutic manipulation of this pathway may be useful for the treatment of human anemia. However, the development of new therapies will await the characterization of an analogous pathway in humans.
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Spicer JI, Rundle SD, Tills O. Studying the altered timing of physiological events during development: It's about time…or is it? Respir Physiol Neurobiol 2011; 178:3-12. [DOI: 10.1016/j.resp.2011.06.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2011] [Revised: 06/03/2011] [Accepted: 06/08/2011] [Indexed: 11/26/2022]
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Harandi OF, Hedge S, Wu DC, McKeone D, Paulson RF. Murine erythroid short-term radioprotection requires a BMP4-dependent, self-renewing population of stress erythroid progenitors. J Clin Invest 2010; 120:4507-19. [PMID: 21060151 DOI: 10.1172/jci41291] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2009] [Accepted: 09/15/2010] [Indexed: 12/24/2022] Open
Abstract
Acute anemic stress induces a systemic response designed to increase oxygen delivery to hypoxic tissues. Increased erythropoiesis is a key component of this response. Recovery from acute anemia relies on stress erythropoiesis, which is distinct from steady-state erythropoiesis. In this study we found that the bone morphogenetic protein 4-dependent (BMP4-dependent) stress erythropoiesis pathway was required and specific for erythroid short-term radioprotection following bone marrow transplantation. BMP4 signaling promoted the development of three populations of stress erythroid progenitors, which expanded in the spleen subsequent to bone marrow transplantation in mice. These progenitors did not correspond to previously identified bone marrow steady-state progenitors. The most immature population of stress progenitors was capable of self renewal while maintaining erythropoiesis without contribution to other lineages when serially transplanted into irradiated secondary and tertiary recipients. These data suggest that during the immediate post-transplant period, the microenvironment of the spleen is altered, which allows donor bone marrow cells to adopt a stress erythropoietic fate and promotes the rapid expansion and differentiation of stress erythroid progenitors. Our results also suggest that stress erythropoiesis may be manipulated through targeting the BMP4 signaling pathway to improve survival after injury.
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Affiliation(s)
- Omid F Harandi
- Center for Molecular Immunology and Infectious Disease, Pennsylvania State University, University Park, Pennsylvania, USA
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23
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Yang YM, Pace B. Pharmacologic Induction of Fetal Hemoglobin Synthesis: Cellular and Molecular Mechanisms. ACTA ACUST UNITED AC 2010. [DOI: 10.1080/15513810109168819] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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24
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Chin J, Singh M, Banzon V, Vaitkus K, Ibanez V, Kouznetsova T, Mahmud N, DeSimone J, Lavelle D. Transcriptional activation of the gamma-globin gene in baboons treated with decitabine and in cultured erythroid progenitor cells involves different mechanisms. Exp Hematol 2009; 37:1131-42. [PMID: 19576949 PMCID: PMC8728742 DOI: 10.1016/j.exphem.2009.06.007] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2009] [Revised: 06/26/2009] [Accepted: 06/29/2009] [Indexed: 12/19/2022]
Abstract
OBJECTIVE To investigate the mechanism(s) responsible for increased gamma-globin expression in vivo in decitabine-treated baboons and in vitro in cultured erythroid progenitor cells (EPC) from adult baboon bone marrow (BM). MATERIALS AND METHODS Fetal liver, adult BM erythroid cells pre- and post-decitabine, and cultured EPCs were analyzed for distribution of RNA polymerase II, histone acetylation, and histone H3 (lys4) trimethyl throughout the gamma-globin gene complex by chromatin immunoprecipitation. DNA methylation of the gamma-globin promoter was determined by bisulfite sequencing. Expression of the baboon Igamma- and Vgamma-globin chains was determined by high performance liquid chromatography (HPLC). Expression of BCL11A, a recently identified repressor of gamma-globin expression, was analyzed by Western blot. RESULTS Increased gamma-globin expression in decitabine-treated baboons and cultured EPC correlated with increased levels of RNA polymerase II, histone acetylation, and histone H3 (lys4) trimethyl associated with the gamma-globin gene consistent with a transcriptional activation mechanism. Cultured EPC expressed the Igamma- and Vgamma-globin chains in a pattern characteristic of fetal development. The level of DNA methylation of the gamma-globin gene promoter in EPC cultures was similar to BM erythroid cells from normal adult baboons. Different BCL11A isoforms were observed in BM erythroid cells and cultured EPC. CONCLUSION The mechanism responsible for increased gamma-globin expression in cultured EPC was unexpectedly not associated with increased DNA hypomethylation of the gamma-globin gene promoter compared to normal BM erythroid cells, in contrast to BM erythroid cells of decitabine-treated baboons. Rather, increased fetal hemoglobin in EPC cultures was associated with a fetal Igamma/Vgamma chain ratio and a difference in the size of the BCL11A protein compared to normal BM erythroid cells.
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Affiliation(s)
- Janet Chin
- Department of Medicine, University of Illinois at Chicago, Chicago, Ill., USA
- Jesse Brown VA Medical Center, Chicago, Ill., USA
| | - Mahipal Singh
- Department of Animal Science and Molecular Biology, Fort Valley State University, Fort Valley, Ga., USA
| | - Virryan Banzon
- Department of Medicine, University of Illinois at Chicago, Chicago, Ill., USA
- Jesse Brown VA Medical Center, Chicago, Ill., USA
| | - Kestis Vaitkus
- Department of Medicine, University of Illinois at Chicago, Chicago, Ill., USA
- Jesse Brown VA Medical Center, Chicago, Ill., USA
| | - Vinzon Ibanez
- Department of Medicine, University of Illinois at Chicago, Chicago, Ill., USA
- Jesse Brown VA Medical Center, Chicago, Ill., USA
| | - Tatiana Kouznetsova
- Department of Medicine, University of Illinois at Chicago, Chicago, Ill., USA
- Jesse Brown VA Medical Center, Chicago, Ill., USA
| | - Nadim Mahmud
- Department of Medicine, University of Illinois at Chicago, Chicago, Ill., USA
| | - Joseph DeSimone
- Department of Medicine, University of Illinois at Chicago, Chicago, Ill., USA
- Jesse Brown VA Medical Center, Chicago, Ill., USA
| | - Donald Lavelle
- Department of Medicine, University of Illinois at Chicago, Chicago, Ill., USA
- Jesse Brown VA Medical Center, Chicago, Ill., USA
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25
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McReynolds LJ, Tucker J, Mullins MC, Evans T. Regulation of hematopoiesis by the BMP signaling pathway in adult zebrafish. Exp Hematol 2008; 36:1604-1615. [PMID: 18973974 DOI: 10.1016/j.exphem.2008.08.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2007] [Revised: 08/12/2008] [Accepted: 08/21/2008] [Indexed: 10/21/2022]
Abstract
OBJECTIVE The zebrafish is an established model system for studying the embryonic emergence of tissues and organs, including the hematopoietic system. We hypothesized that key signaling pathways controlling embryonic hematopoiesis continue to be important in the adult, and we sought to develop approaches to test this in zebrafish, focused on the bone morphogenetic protein (BMP) signaling pathway. Functions for this pathway in adult hematopoiesis have been challenging to probe in other models. MATERIALS AND METHODS Several approaches tested the function of BMP signaling during adult zebrafish hematopoiesis. First, we evaluated steady-state hematopoiesis in adult fish that are heterozygous for mutant alleles of Smad5, or are homozygous for mutant alleles, and rescued to adulthood by injection of RNA encoding Smad5. Second, we tested the relative ability of smad5 mutant fish to recover from hemolytic anemia. Third, we generated a transgenic line that targets the expression of a dominant-negative BMP receptor to adult-stage Gata1+ progenitor cells. RESULTS Adult fish with a strong mutant smad5 allele are anemic at steady state and, in addition, respond to hemolytic anemia with kinetics that are altered compared to wild-type fish. Fish expressing a mutant BMP receptor in early Gata1+ definitive progenitors generate excessive eosinophils. CONCLUSIONS Our study provides proof of principle that regulation of adult hematopoiesis can be studied in zebrafish by altering specific pathways. We show that the BMP signaling pathway is relevant for adult hematopoiesis to maintain steady state erythropoiesis, control the erythropoietic response following stress anemia, and to generate normal numbers of eosinophils.
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Affiliation(s)
- Lisa J McReynolds
- Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, Bronx, NY 10461, USA
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26
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Bhanu NV, Lee YT, Oneal PA, Gantt NM, Aerbajinai W, Noel P, Thomas CJ, Miller JL. Inhibition of erythroblast growth and fetal hemoglobin production by ribofuranose-substituted adenosine derivatives. Biochim Biophys Acta Mol Basis Dis 2008; 1782:504-10. [PMID: 18586086 DOI: 10.1016/j.bbadis.2008.05.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2007] [Revised: 05/14/2008] [Accepted: 05/14/2008] [Indexed: 10/22/2022]
Abstract
In vivo, inhibition of fetal hemoglobin (HbF) expression in humans around the time of birth causes the clinical manifestation of sickle cell and beta-thalassemia syndromes. Inhibition of HbF among cultured cells was recently described by the adenosine derivative molecule named SQ22536. Here, a primary cell culture model was utilized to further explore the inhibition of HbF by adenosine derivative molecules. SQ22536 demonstrated down-regulation of growth and HbF expression among erythroblasts cultured from fetal and adult human blood. The effects upon HbF were noted in a majority of cells, and quantitative PCR analysis demonstrated a transcriptional mechanism. Screening assays demonstrated that two additional molecules named 5'-deoxy adenosine and 2',3'-dideoxy adenosine had effects on HbF comparable to SQ22536. Other adenosine derivative molecules, adenosine receptor binding ligands, and cAMP-signaling regulators failed to inhibit HbF in matched cultures. These results suggest that structurally related ribofuranose-substituted adenosine analogues act through an unknown mechanism to inhibit HbF expression in fetal and adult human erythroblasts.
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Affiliation(s)
- Natarajan V Bhanu
- Molecular Medicine Branch, National Institute of Diabetes and Digestive and Kidney Diseases, Laboratory Medicine Department, Hematology Service, National Institutes of Health, Bethesda, MD 20892, USA
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27
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Kar R, Saxena R, Pati HP. Hereditary Spherocytosis with High Fetal Hemoglobin: An Interesting Case. Hemoglobin 2008; 32:520-3. [DOI: 10.1080/03630260802341976] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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28
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Hsieh MM, Linde NS, Wynter A, Metzger M, Wong C, Langsetmo I, Lin A, Smith R, Rodgers GP, Donahue RE, Klaus SJ, Tisdale JF. HIF prolyl hydroxylase inhibition results in endogenous erythropoietin induction, erythrocytosis, and modest fetal hemoglobin expression in rhesus macaques. Blood 2007; 110:2140-7. [PMID: 17557894 PMCID: PMC1976368 DOI: 10.1182/blood-2007-02-073254] [Citation(s) in RCA: 138] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The hypoxia-inducible factor (HIF) pathway is crucial in mitigating the deleterious effects of oxygen deprivation. HIF-alpha is an essential component of the oxygen-sensing mechanisms and under normoxic conditions is targeted for degradation via hydroxylation by HIF-prolyl hydroxylases. Several HIF-prolyl hydroxylase inhibitors (PHIs) induced erythropoietin (epo) expression in vitro and in mice, with peak epo expression ranging from 5.6- to 207-fold above control animals. Furthermore, several PHIs induced fetal hemoglobin (HbF) expression in primary human erythroid cells in vitro, as determined by flow cytometry. One PHI, FG-2216, was further tested in a nonhuman primate model without and with chronic phlebotomy. FG-2216 was orally bioavailable and induced significant and reversible Epo induction in vivo (82- to 309-fold at 60 mg/kg). Chronic oral dosing in male rhesus macaques was well tolerated, significantly increased erythropoiesis, and prevented anemia induced by weekly phlebotomy. Furthermore, modest increases in HbF-containing red cells and reticulocytes were demonstrated by flow cytometry, though significant increases in HbF were not demonstrated by high-pressure liquid chromatography (HPLC). HIF PHIs represent a novel class of molecules with broad potential clinical application for congenital and acquired anemias.
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Affiliation(s)
- Matthew M Hsieh
- Molecular and Clinical Hematology Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
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29
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Mabaera R, Richardson CA, Johnson K, Hsu M, Fiering S, Lowrey CH. Developmental- and differentiation-specific patterns of human gamma- and beta-globin promoter DNA methylation. Blood 2007; 110:1343-52. [PMID: 17456718 PMCID: PMC1939907 DOI: 10.1182/blood-2007-01-068635] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The mechanisms underlying the human fetal-to-adult beta-globin gene switch remain to be determined. While there is substantial experimental evidence to suggest that promoter DNA methylation is involved in this process, most data come from studies in nonhuman systems. We have evaluated human gamma- and beta-globin promoter methylation in primary human fetal liver (FL) and adult bone marrow (ABM) erythroid cells. Our results show that, in general, promoter methylation and gene expression are inversely related. However, CpGs at -162 of the gamma promoter and -126 of the beta promoter are hypomethylated in ABM and FL, respectively. We also studied gamma-globin promoter methylation during in vitro differentiation of erythroid cells. The gamma promoters are initially hypermethylated in CD34(+) cells. The upstream gamma promoter CpGs become hypomethylated during the preerythroid phase of differentiation and are then remethylated later, during erythropoiesis. The period of promoter hypomethylation correlates with transient gamma-globin gene expression and may explain the previously observed fetal hemoglobin production that occurs during early adult erythropoiesis. These results provide the first comprehensive survey of developmental changes in human gamma- and beta-globin promoter methylation and support the hypothesis that promoter methylation plays a role in human beta-globin locus gene switching.
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Affiliation(s)
- Rodwell Mabaera
- Department of Pharmacology and Toxicology, Dartmouth Medical School, Hanover, NH, USA
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30
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Oneal PA, Gantt NM, Schwartz JD, Bhanu NV, Lee YT, Moroney JW, Reed CH, Schechter AN, Luban NLC, Miller JL. Fetal hemoglobin silencing in humans. Blood 2006; 108:2081-6. [PMID: 16735596 PMCID: PMC1895549 DOI: 10.1182/blood-2006-04-015859] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Interruption of the normal fetal-to-adult transition of hemoglobin expression should largely ameliorate sickle cell and beta-thalassemia syndromes. Achievement of this clinical goal requires a robust understanding of gamma-globin gene and protein silencing during human development. For this purpose, age-related changes in globin phenotypes of circulating human erythroid cells were examined from 5 umbilical cords, 99 infants, and 5 adult donors. Unexpectedly, an average of 95% of the cord blood erythrocytes and reticulocytes expressed HbA and the adult beta-globin gene, as well as HbF and the gamma-globin genes. The distribution of hemoglobin and globin gene expression then changed abruptly due to the expansion of cells lacking HbF or gamma-globin mRNA (silenced cells). In adult reticulocytes, less than 5% expressed gamma-globin mRNA. These data are consistent with a "switching" model in humans that initially results largely from gamma- and beta-globin gene coexpression and competition during fetal development. In contrast, early postnatal life is marked by the rapid accumulation of cells that possess undetectable gamma-globin mRNA and HbF. The silencing phenomenon is mediated by a mechanism of cellular replacement. This novel silencing pattern may be important for the development of HbF-enhancing therapies.
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Affiliation(s)
- Patricia A Oneal
- Molecular Medicine Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, 10 Center Drive, Bldg 10, Rm 9B17, Bethesda, MD 20892, USA
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31
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Cao H, Jung M, Stamatoyannopoulos G. Hydroxamide derivatives of short-chain fatty acid have erythropoietic activity and induce gamma gene expression in vivo. Exp Hematol 2006; 33:1443-9. [PMID: 16338486 DOI: 10.1016/j.exphem.2005.08.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2005] [Revised: 08/19/2005] [Accepted: 08/19/2005] [Indexed: 11/20/2022]
Abstract
OBJECTIVE The hydroxamic acid derivatives of short-chain fatty acids, butyryl and propionyl hydroxamate, subericbishydoxamic acid, and suberoylanilide hydroxamic acid, are potent inhibitors of histone deacetylase (HDAC) and have been shown to induce fetal hemoglobin in vitro. In this study we examined whether these compounds have erythropoietic activity and can induce gamma globin gene expression in vivo. MATERIALS AND METHODS Transgenic mice heterozygous for a deletion beta thalassemia and hemizygous for a human gamma globin transgene were treated with these compounds and hematologic responses as well as the induction of gamma gene expression were evaluated. Hematologic studies included measurement of reticulocytes, hematocrit, and the in vivo levels of BFU-E. Effects on globin gene expression were assessed by measuring F reticulocytes and the human gamma/murine alpha globin mRNA ratios by RNAse protection assay. RESULTS Propionyl and butyryl hydroxamate increased reticulocytes by 71% and 139%, the in vivo BFU-E counts by 75% and 51%, and the in vivo gamma gene expression by 33.9% and 71% respectively. SBHA and SAHA had no erythropoietic activity in vivo. CONCLUSION Hydroxamic acid derivatives can stimulate the in vivo erythropoiesis and fetal globin production in a thalassemic murine model. The combined effect of certain histone deacetylase inhibitors on erythropoiesis and on gamma gene expression make these compounds desirable targets for development of therapeutics for beta chain hemoglobinopathies.
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Affiliation(s)
- Hua Cao
- Division of Medical Genetics, University of Washington, Seattle, 98195, USA.
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32
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Stamatoyannopoulos G. Control of globin gene expression during development and erythroid differentiation. Exp Hematol 2005; 33:259-71. [PMID: 15730849 PMCID: PMC2819985 DOI: 10.1016/j.exphem.2004.11.007] [Citation(s) in RCA: 275] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2004] [Accepted: 11/05/2004] [Indexed: 11/29/2022]
Abstract
Extensive studies during the last 30 years have led to considerable understanding of cellular and molecular control of hemoglobin switching. Cell biology studies in the 1970s defined the control of globin genes during erythroid differentiation and led to development of therapies for sickle cell disease. Molecular investigations of the last 20 years have delineated the two basic mechanisms that control globin gene activity during development--autonomous silencing and gene competition. Studies of hemoglobin switching have provided major insights on the control of gene loci by remote regulatory elements. Research in this field has an impact on understanding regulatory mechanisms in general and is of particular importance for eventual development of molecular cures for sickle cell disease and beta thalassemia.
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Affiliation(s)
- George Stamatoyannopoulos
- Department of Medicine, Division of Medical Genetics, University of Washington, Seattle, WA 98195, USA.
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33
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Cao H, Stamatoyannopoulos G, Jung M. Induction of human gamma globin gene expression by histone deacetylase inhibitors. Blood 2004; 103:701-9. [PMID: 12920038 PMCID: PMC2808412 DOI: 10.1182/blood-2003-02-0478] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We investigated the induction of human gamma globin gene activity by 3 classes of histone deacetylase inhibitors: amide analogues of trichostatin A, hydroxamic acid analogues of trapoxin, and scriptaid and its analogues. The screening consisted of measuring the effects of these compounds on gamma and beta human gene promoter activity by using cultures of GM979 cells stably transfected with a construct containing a gamma promoter linked to firefly luciferase and a beta promoter linked to renilla luciferase. Compounds belonging to all 3 classes induced gamma gene promoter activity in the screening assay in low micromolar concentrations. Histone deacetylase (HDAC) inhibitors increased acetylation of histone H4 and induced the expression of endogenous murine embryonic genes. They also increased the levels of gamma mRNA and the frequency of fetal hemoglobin-containing erythroblasts in erythroid burst-forming unit (BFUe) cultures from healthy adult individuals. Compounds that displayed very similar degrees of inhibition of the HDAC activity in an HDAC enzymatic assay differed strikingly on their effects on gamma gene promoter activity, raising the possibility of selectivity of HDACs that interact with the gamma globin gene chromatin.
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Affiliation(s)
- Hua Cao
- Medical Genetics, Box 357720, University of Washington, Seattle, WA 98195, USA
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34
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Bard H, Côté A, Praud JP, Infante-Rivard C, Gagnon C. Fetal hemoglobin synthesis determined by gamma-mRNA/gamma-mRNA + beta-mRNA quantitation in infants at risk for sudden infant death syndrome being monitored at home for apnea. Pediatrics 2003; 112:e285. [PMID: 14523213 DOI: 10.1542/peds.112.4.e285] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
OBJECTIVE Fetal hemoglobin (HbF) levels in the hemolysates obtained from infants who died from sudden infant death syndrome (SIDS) are reported to be markedly increased compared with controls. This finding could have been explained by increased HbF synthesis caused by episodes of hypoxemia in the SIDS infants. A prospective study in a group of infants being monitored at home after an apparent life-threatening event (ALTE) and considered at increased risk for SIDS was conducted with an improved ribonuclease protection assay. The ribonuclease protection assay allowed for the quantitation of [gamma/(gamma+beta)]-globin mRNAs, which has a highly significant correlation with the levels of HbF synthesis. METHODS Thirty-five infants who were admitted for an ALTE were included in the study. All infants were at home under surveillance with a cardiorespiratory monitor and followed in an apnea clinic with monthly appointments. Seventy-three blood samples were obtained between 38 and 61 weeks of postconceptional age. For control purposes, a similar group of 37 normal infants (99 samples) whose HbF synthesis was previously determined were included. RESULTS Mean [gamma/(gamma+beta)]-globin mRNAs were increased in the ALTE group at 42 to 45 and 46 to 49 weeks of postconceptional age (mean: 55.2 +/- 17.4% and 33.9 +/- 14%) in comparison with HbF synthesis in controls (mean: 42.6 +/- 13.7% and 23.6 +/- 9.8%). CONCLUSIONS The data obtained in this report from infants who were considered at risk for SIDS show that HbF synthesis is increased between 42 and 49 weeks of postconceptional age. Determining HbF synthesis as described in this study may have value as a marker for episodes of hypoxemia for certain infants who are at risk for SIDS.
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Affiliation(s)
- Harry Bard
- Division of Neonatology, Department of Pediatrics, University of Montreal, Ste-Justine Hospital and Research Center, Montreal, Quebec, Canada.
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35
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Skarpidi E, Cao H, Heltweg B, White BF, Marhenke RL, Jung M, Stamatoyannopoulos G. Hydroxamide derivatives of short-chain fatty acids are potent inducers of human fetal globin gene expression. Exp Hematol 2003; 31:197-203. [PMID: 12644016 DOI: 10.1016/s0301-472x(02)01030-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVE To examine whether hydroxamic acids are inducers of fetal hemoglobin expression, we tested the effects on gamma gene expression of butyric and propionic hydroxamic acids and of two other hydroxamic acids (SBHA and SAHA), which are potent inhibitors of histone deacetylase (HDAC). We also investigated whether there is a correlation between HDAC inhibitory activity of the compounds and their ability to induce gamma-globin gene expression. MATERIALS AND METHODS Effects on gamma-globin expression were assessed by two methods: 1) a screening assay in which specific gamma-globin gene inducers are recognized by their ability to increase gamma firefly luciferase activity significantly more than beta-renilla luciferase activity; and 2) measurements of gamma-globin mRNA and the frequency of fetal hemoglobin-positive erythroblasts in cultures of burst-forming unit erythroid (BFU-E) from normal individuals. HDAC in vitro activity was measured with a partially purified rat liver HDAC and a fluorogenic substrate. RESULTS All compounds tested increased gamma firefly luciferase activity, gamma/gamma+beta mRNA ratios, and percentage of fetal hemoglobin-containing erythroblasts in BFU-E cultures, in a dose-dependent fashion. Butyryl-hydroxamic acid 100 microM increased the gamma/gamma+beta mRNA ratios by 5.8-fold and the frequency of fetal hemoglobin-containing erythroblasts by 4.1-fold. Propionyl-hydroxamic acid 150 microM increased the gamma/gamma+beta ratios by 6.3-fold and the fetal hemoglobin-containing erythroblasts by 3.9-fold. SBHA induced gamma-globin gene expression at very low concentrations, 5 to 20 microM in the luciferase system and 2 to 8 microM in BFU-E cultures; SAHA at 1 to 7.5 microM in the luciferase system and 1 to 2.5 microM in the BFU-E cultures. HDAC in vitro inhibition was observed in the millimolar range for propionate and butyrate. IC(50) determinations led to values of 384 microM for propionyl-hydroxamate, 47 microM for butyryl-hydroxamate, 0.93 microM for SBHA, and 0.26 microM for SAHA. CONCLUCION: Our data indicate that hydroxamic acid-based HDAC inhibitors are potent gamma-globin gene inducers and that the concentration range of their effects on gamma gene expression can be correlated roughly with their HDAC inhibitory potencies.
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Affiliation(s)
- Evangelia Skarpidi
- Division of Medical Genetics, University of Washington, Seattle, Wash 98195, USA
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36
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Bard H, Gagnon C, Peri KG. HbF synthesis during stress erythropoiesis as determined by gamma-mRNA/non-alpha-mRNA quantification. Pediatr Res 1999; 45:684-6. [PMID: 10231865 DOI: 10.1203/00006450-199905010-00013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
To determine whether a quantitative relationship exists between globin mRNAs and their translation product during stress erythropoiesis in infants with increased production of fetal hemoglobin (HbF), we measured and compared the relative amounts of the mRNAs of alpha-, beta-, and gamma-globins and their protein synthesis. The synthesis of globin in immature red cells was determined by the incorporation of [3H]leucine, followed by separation and quantification of the polypeptides by C4-reverse phase HPLC. The relative proportions of the mRNAs of the globins were determined by RNase protection assay. A comparison of blood samples from 17 infants expected to have increased production of HbF in relation to their developmental age (five infants of diabetic mothers, two infants with intrauterine growth retardation, one infant with bronchopulmonary dysplasia, and seven infants with cyanotic heart disease) revealed a very significant correlation (r2 = 0.994; p < 0.001) between the ratio of globin mRNAs encoding HbF ([gamma/(gamma + beta)] mRNAs) and the ratios of the de novo synthesis of HbF [gamma/(gamma + beta)]. When only the 10 infants who had increased HbF synthesis are included, the correlation remains unchanged (r2 = 0.997, p < 0.001). The data demonstrated that under conditions of erythropoietic stress, when HbF production is increased, there is a close relationship between the quantification of gamma-globin mRNA and gamma-globin synthesis. The usual methods of determining HbF synthesis can be replaced by globin mRNA determination, which can be performed rapidly with a minimal amount of blood.
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Affiliation(s)
- H Bard
- Department of Pediatrics, University of Montreal, Hospital Sainte-Justine, Canada.
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37
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Bichet S, Wenger RH, Camenisch G, Rolfs A, Ehleben W, Porwol T, Acker H, Fandrey J, Bauer C, Gassmann M. Oxygen tension modulates beta-globin switching in embryoid bodies. FASEB J 1999; 13:285-95. [PMID: 9973316 DOI: 10.1096/fasebj.13.2.285] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Little is known about the factors influencing the hemoglobin switch in vertebrates during development. Inasmuch as the mammalian conceptus is exposed to changing oxygen tensions in utero, we examined the effect of different oxygen concentrations on beta-globin switching. We used an in vitro model of mouse embryogenesis based on the differentiation of blastocyst-derived embryonic stem cells to embryoid bodies (EBs). Cultivation of EBs at increasing oxygen concentrations (starting at 1% O2) did not influence the temporal expression pattern of embryonic (betaH1) globin compared to the normoxic controls (20% O2). In contrast, when compared to normoxically grown EBs, expression of fetal/adult (betamaj) globin in EBs cultured at varying oxygen concentrations was delayed by about 2 days and persisted throughout differentiation. Quantitation of hemoglobin in EBs using a 2,7-diaminofluorene-based colorimetric assay revealed the appearence of hemoglobin in two waves, an early and a late one. This observation was verified by spectrophotometric analysis of hemoglobin within single EBs. These two waves might reflect the switch of erythropoiesis from yolk sac to fetal liver. Reduced oxygenation is known to activate the hypoxia-inducible factor-1 (HIF-1), which in turn specifically induces expression of a variety of genes among them erythropoietin (EPO). Although EBs increased EPO expression upon hypoxic exposure, the altered beta-globin appearance was not related to EPO levels as determined in EBs overexpressing EPO. Since mRNA from both mouse HIF-1alpha isoforms was detected in all EBs tested at different differentiation stages, we propose that HIF-1 modulates beta-globin expression during development.
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Affiliation(s)
- S Bichet
- Institute of Physiology, University of Zürich-Irchel, 8057 Zürich, Switzerland
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Fibach E, Schechter AN, Noguchi CT, Rodgers GP. Reducing erythropoietin in cultures of human erythroid precursors elevates the proportion of fetal haemoglobin. Br J Haematol 1994; 88:39-45. [PMID: 7528530 DOI: 10.1111/j.1365-2141.1994.tb04974.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
In order to clarify the mechanism of the effect of erythropoietin (Epo) on the fetal haemoglobin (HbF) phenotype of peripheral erythrocytes, we studied the dose-response effect of Epo on HbF production by erythroid precursors derived from the peripheral blood of normal adult individuals and grown in a two-phase liquid culture system. The proportion of HbF out of the total haemoglobin (Hb) content (%HbF) was dependent on the duration of exposure to Epo; on day 6 it comprised up to 15%, but dropped to < 2% on day 14. Both cell yield and cellular Hb content were markedly increased by high (1 U/ml) Epo, compared to normal physiological (20-50 mU/ml) levels, but neither the initial nor final %HbF were dependent on the increased Epo dose. However, when cells grown with high Epo were transferred on day 7 to low Epo, their progeny contained by day 14 a higher %HbF as compared to cells that were continuously exposed to high Epo. This was accompanied by acceleration and synchronization of their maturation process, as evidenced by their morphology, density and size, and restriction on cell multiplication, as indicated by the lower cell yield. These results are consistent with the following model. As early erythroid precursors, with relatively high HbF, mature under steady-state levels of Epo, HbA production predominates and HbF is diluted. However, when such precursors are switched from high to low levels of Epo they undergo a synchronized, accelerated maturation which shortens the period of HbA production, leading to a decreased Hb content and a relatively high proportion of HbF. This mechanism may contribute to the elevated HbF observed following Epo administration (due to short half-life of Epo in vivo), and might also explain the HbF-augmenting effect of Epo administered together with hydroxyurea observed in patients with sickle cell anaemia.
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Affiliation(s)
- E Fibach
- Department of Haematology, Hadassah University Hospital, Jerusalem, Israel
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Abstract
Fetal hemoglobin (HbF) synthesis in children with congenital cyanotic heart disease was compared that in normal children. Children with hypoxemia had higher levels of hemoglobin, total HbF, and HbF synthesis. In these children there was also an inverse correlation between HbF synthesis and oxygen content, as well as between HbF synthesis and hemoglobin concentration. Thus hypoxemia increases HbF synthesis.
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Affiliation(s)
- H Bard
- Neonatology Service, St. Justine's Hospital, Montreal, Quebec, Canada
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Gabbianelli M, Pelosi E, Valtieri M, Scalzo S, Testa U, Peschle C. A model for reactivation of hemoglobin F synthesis in normal adult erythropoiesis. Ann N Y Acad Sci 1990; 612:196-206. [PMID: 1705409 DOI: 10.1111/j.1749-6632.1990.tb24307.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- M Gabbianelli
- Department of Hematology-Oncology, Istituto Superiore di Sanità, Rome, Italy
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Zeller R, Bloch KD, Williams BS, Arceci RJ, Seidman CE. Localized expression of the atrial natriuretic factor gene during cardiac embryogenesis. Genes Dev 1987; 1:693-8. [PMID: 2962900 DOI: 10.1101/gad.1.7.693] [Citation(s) in RCA: 165] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Expression of the gene encoding atrial natriuretic factor (ANF) during mouse cardiac embryogenesis was studied using in situ hybridization to histologic sections. ANF mRNA was first detected in a subpopulation of myocardial cells at day 8 of embryogenesis. During day 9, abundant hybridization of the ANF probe to the atrium and the primitive ventricle was found. At day 14, strong labeling of cells in both atria and the trabeculated regions of the left ventricle was seen, whereas fewer cells in the right ventricle expressed the ANF gene. The developmental regulation of ANF gene expression in atrial and ventricular cells suggests an important role for this peptide hormone in the embryo. Localized expression of the ANF gene provides a marker for discerning subpopulations of cardiac cells during embryogenesis. Identification of embryonic ventricular ANF mRNA transcripts may have implications with respect to pathologic reexpression of the ANF gene in adult ventricles.
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Affiliation(s)
- R Zeller
- Department of Genetics, Harvard Medical School, Boston, Massachusetts
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43
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Abstract
Application of recombinant DNA technology to the study of atrial natriuretic factor (ANF) has significantly increased our understanding of the biochemistry and physiology of this cardiac hormone. Molecular characterization of the ANF gene and mRNA has yielded structural details about this peptide, and provided tools to investigate maturation, storage, and secretion of a cardiac hormone. Genetic probes have facilitated analyses of the role of a natriuretic and vasorelaxant hormone in pathophysiologic states. Furthermore, studies on the regulation of this cardiac gene have begun to provide data on the molecular basis for biochemical changes in the heart that occur in response to physiologic and pathologic processes.
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Affiliation(s)
- C E Seidman
- Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115
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Al-Khatti A, Veith RW, Papayannopoulou T, Fritsch EF, Goldwasser E, Stamatoyannopoulos G. Stimulation of fetal hemoglobin synthesis by erythropoietin in baboons. N Engl J Med 1987; 317:415-20. [PMID: 2441258 DOI: 10.1056/nejm198708133170704] [Citation(s) in RCA: 94] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Stimulating the production of fetal hemoglobin may benefit patients with sickle cell anemia by inhibiting sickling. We gave pulsed treatments with high doses of recombinant human erythropoietin to baboons in order to test the hypothesis that the resultant rapid erythroid regeneration would stimulate F cells--i.e., cells that contain fetal hemoglobin. In normal animals, this treatment caused sharp increments in F-reticulocyte levels, which rose from 1 to 2 percent before treatment to 40 to 50 percent afterward. In two animals with chronic anemia and high levels of endogenous erythropoietin, recombinant human erythropoietin induced further increments in F-reticulocyte levels, which rose in one animal from 6 to 8 percent before treatment to 23 percent after treatment, and in the other from 20 percent before to 50 percent afterward. The time course of F-reticulocyte stimulation suggested that these cells were the products of mobilized early erythroid progenitors. These results raise the possibility that pulses of erythropoietin could be used to stimulate F-cell formation in patients with sickle cell disease.
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Veith R, Galanello R, Papayannopoulou T, Stamatoyannopoulos G. Stimulation of F-cell production in patients with sickle-cell anemia treated with cytarabine or hydroxyurea. N Engl J Med 1985; 313:1571-5. [PMID: 2415821 DOI: 10.1056/nejm198512193132503] [Citation(s) in RCA: 112] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
To investigate the mechanism of pharmacologic stimulation of fetal hemoglobin in sickle-cell anemia (hemoglobin S disease), we treated two patients with homozygous disease with various doses of cytarabine (also known as Ara-C) or hydroxyurea and evaluated the effects of each treatment on F-reticulocyte production and on hemopoiesis. The treatments stimulated F-cell production in a dose-related fashion. Treatments that increased F-cell production also increased the patient's hematocrit and caused only minor, transient decreases in white cells. The main effect on erythropoiesis consisted of cytoreduction of the mature erythron (as assessed by measurements of reticulocytes) or a decrease in the compartment of erythroid progenitors (colony-forming units--erythroid and burst-forming units--erythroid). The reduction phase was followed by reticulocyte regeneration, during which most of the increase in the absolute numbers of F reticulocytes took place. Lower doses of cytarabine or hydroxyurea resulted in smaller waves of reticulocyte regeneration and lesser effects on F-reticulocyte production. These results suggest that the main cause of stimulation of fetal hemoglobin in patients with sickle-cell anemia treated with cell cycle-specific compounds is the erythroid regeneration triggered by the drug treatment.
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Stamatoyannopoulos G, Veith R, Galanello R, Papayannopoulou T. Hb F production in stressed erythropoiesis: observations and kinetic models. Ann N Y Acad Sci 1985; 445:188-97. [PMID: 2409871 DOI: 10.1111/j.1749-6632.1985.tb17188.x] [Citation(s) in RCA: 57] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The mechanism of stimulation of Hb F in stressed erythropoiesis is examined. Conditions known to produce a transient elevation of F-cells (acute anemia; acute expansion; treatment with cytotoxic compounds) have a common element, the acute kinetic perturbations of erythroid differentiation/maturation they trigger. Cell cycling must be shortened and the total time of differentiation (from BFUe to erythroblast) must be shortened. We propose that F-cells are formed either because of the shortening of erythroid differentiation time or because of shortening of cell cycle of erythroid cells. With the model of shortened differentiation time F-cell formation is attributed to "premature commitment" of progenitors. gamma-gene expression occurs either because chromatin changes that normally inactivate the gamma genes are not completed or because critical divisions in which the gamma genes are normally inactivated are skipped. The model of faster cycling explains F-cell formation by assuming that gamma-gene transcription is activated when the cycle (and especially the duration of G0/G1) of progenitors or erythroblasts falls below a critical time. The proposed models can readily explain the F-cells of the normal adult as the products of random deviation from normal erythroid kinetics. The two models can also explain F-cell formation in chronic erythropoietic stress (chronic hemolytic anemias, patients with hemoglobinopathies). Differences in the degree of F-cell elevation in such patients may reflect differences in the intensity of kinetic perturbation of their erythropoiesis.
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Abstract
The evidence that 5-azacytidine stimulates the production of Hb F and F cells in baboon and man is reviewed. The mechanism of this effect is not entirely clear, but 5-azacytidine produces hypomethylation of the gamma gene at certain sites, and gene expression and DNA hypomethylation are related phenomena in many other systems. Other mechanisms have been postulated by other investigators. The therapeutic significance of increased Hb F levels in homozygous beta thalassemia and sickle cell anemia is exemplified. The potential risk of carcinogenicity has delayed more extensive clinical trials.
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Nalbandian RM, Cypress GC. Gene switching -- a new therapeutic epoch: discussion paper. J R Soc Med 1984; 77:217-20. [PMID: 6199499 PMCID: PMC1439847 DOI: 10.1177/014107688407700312] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
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Collins FS, Weissman SM. The molecular genetics of human hemoglobin. PROGRESS IN NUCLEIC ACID RESEARCH AND MOLECULAR BIOLOGY 1984; 31:315-462. [PMID: 6397774 DOI: 10.1016/s0079-6603(08)60382-7] [Citation(s) in RCA: 299] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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