101
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Inhibition of G9a methyltransferase stimulates fetal hemoglobin production by facilitating LCR/γ-globin looping. Blood 2015; 126:665-72. [PMID: 25979948 DOI: 10.1182/blood-2015-02-629972] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2015] [Accepted: 05/11/2015] [Indexed: 12/16/2022] Open
Abstract
Induction of fetal hemoglobin (HbF) production in adult erythrocytes can reduce the severity of sickle cell disease and β-thalassemia. Transcription of β-globin genes is regulated by the distant locus control region (LCR), which is brought into direct gene contact by the LDB1/GATA-1/TAL1/LMO2-containing complex. Inhibition of G9a H3K9 methyltransferase by the chemical compound UNC0638 activates fetal and represses adult β-globin gene expression in adult human hematopoietic precursor cells, but the underlying mechanisms are unclear. Here we studied UNC0638 effects on β-globin gene expression using ex vivo differentiation of CD34(+) erythroid progenitor cells from peripheral blood of healthy adult donors. UNC0638 inhibition of G9a caused dosed accumulation of HbF up to 30% of total hemoglobin in differentiated cells. Elevation of HbF was associated with significant activation of fetal γ-globin and repression of adult β-globin transcription. Changes in gene expression were associated with widespread loss of H3K9me2 in the locus and gain of LDB1 complex occupancy at the γ-globin promoters as well as de novo formation of LCR/γ-globin contacts. Our findings demonstrate that G9a establishes epigenetic conditions preventing activation of γ-globin genes during differentiation of adult erythroid progenitor cells. In this view, manipulation of G9a represents a promising epigenetic approach for treatment of β-hemoglobinopathies.
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102
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Zhang W, Liu H, Liu W, Liu Y, Xu J. Polycomb-mediated loss of microRNA let-7c determines inflammatory macrophage polarization via PAK1-dependent NF-κB pathway. Cell Death Differ 2015; 22:287-97. [PMID: 25215948 PMCID: PMC4291490 DOI: 10.1038/cdd.2014.142] [Citation(s) in RCA: 69] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Revised: 08/04/2014] [Accepted: 08/06/2014] [Indexed: 02/06/2023] Open
Abstract
Serine/threonine kinase family members p21-activated kinases (PAKs) are important regulators of cytoskeletal remodeling and cell motility in mononuclear phagocytic system, but their role in macrophage differentiation and polarization remains obscure. We have shown here that inflammatory stimuli induced PAK1 overexpression in human and murine macrophages. Elevated expression of PAK1 contributed to macrophage M1 polarization and lipopolysaccharide (LPS)-induced endotoxin shock. We further observed that epigenetic loss of microRNA let-7c due to enhancer of zeste homolog 2 (EZH2) upregulation determined PAK1 elevation and inflammatory phenotype in M1 macrophages. EZH2/let-7c/PAK1 axis promotes macrophage M1 polarization via NIK-IKK-NF-κB signaling. Moreover, pharmacological and genetic ablation with EZH2/let-7c/PAK1 axis blunted inflammatory phenotype in M1 macrophages. Critically, either myeloid-restricted PAK1 deletion (PAK1(Lyz2cre)) or pharmacological and genetic ablation with EZH2/let-7c/PAK1 signal resulted in resistance to LPS-induced endotoxin shock via blunting macrophage M1 polarization. PAK1, therefore, is an essential controller of inflammatory macrophage polarization, regulating immune responses against pathogenic stimuli.
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Affiliation(s)
- W Zhang
- Department of Immunology, School of Basic Medical Sciences, Shanghai Medical College of Fudan University, Shanghai 200032, China
| | - H Liu
- Key Laboratory of Glycoconjugate Research, Ministry of Health, Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Shanghai Medical College of Fudan University, Shanghai 200032, China
| | - W Liu
- Key Laboratory of Glycoconjugate Research, Ministry of Health, Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Shanghai Medical College of Fudan University, Shanghai 200032, China
| | - Y Liu
- Key Laboratory of Glycoconjugate Research, Ministry of Health, Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Shanghai Medical College of Fudan University, Shanghai 200032, China
| | - J Xu
- Key Laboratory of Glycoconjugate Research, Ministry of Health, Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Shanghai Medical College of Fudan University, Shanghai 200032, China
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103
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Lessard S, Beaudoin M, Benkirane K, Lettre G. Comparison of DNA methylation profiles in human fetal and adult red blood cell progenitors. Genome Med 2015; 7:1. [PMID: 25606059 PMCID: PMC4298057 DOI: 10.1186/s13073-014-0122-2] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Accepted: 12/09/2014] [Indexed: 11/21/2022] Open
Abstract
Background DNA methylation is an epigenetic modification that plays an important role during mammalian development. Around birth in humans, the main site of red blood cell production moves from the fetal liver to the bone marrow. DNA methylation changes at the β-globin locus and a switch from fetal to adult hemoglobin production characterize this transition. Understanding this globin switch may improve the treatment of patients with sickle cell disease and β-thalassemia, two of the most common Mendelian diseases in the world. The goal of our study was to describe and compare the genome-wide patterns of DNA methylation in fetal and adult human erythroblasts. Methods We used the Illumina HumanMethylation 450 k BeadChip to measure DNA methylation at 402,819 CpGs in ex vivo-differentiated erythroblasts from 12 fetal liver and 12 bone marrow CD34+ donors. Results We identified 5,937 differentially methylated CpGs that overlap with erythroid enhancers and binding sites for erythropoiesis-related transcription factors. Combining this information with genome-wide association study results, we show that erythroid enhancers define particularly promising genomic regions to identify new genetic variants associated with fetal hemoglobin (HbF) levels in humans. Many differentially methylated CpGs are located near genes with unanticipated roles in red blood cell differentiation and proliferation. For some of these new candidate genes, we confirm the correlation between DNA methylation and gene expression levels in red blood cell progenitors. We also provide evidence that DNA methylation and genetic variation at the β-globin locus independently control globin gene expression in adult erythroblasts. Conclusions Our DNA methylome maps confirm the widespread dynamic changes in DNA methylation that occur during human erythropoiesis. These changes tend to happen near erythroid enhancers, further highlighting their importance in erythroid regulation and HbF production. Finally, DNA methylation may act independently of the transcription factor BCL11A to repress fetal hemoglobin production. This provides cues on strategies to more efficiently re-activate HbF production in sickle cell disease and β-thalassemia patients. Electronic supplementary material The online version of this article (doi:10.1186/s13073-014-0122-2) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Samuel Lessard
- Montreal Heart Institute, 5000 Bélanger Street, Montréal, Québec H1T 1C8 Canada ; Faculté de Médecine, Université de Montréal, 2900 Boul. Édouard-Montpetit, Montréal, Québec H3T 1J4 Canada
| | - Mélissa Beaudoin
- Montreal Heart Institute, 5000 Bélanger Street, Montréal, Québec H1T 1C8 Canada
| | - Karim Benkirane
- Hôpital Maisonneuve-Rosemont, 5415 Boul. de l'Assomption, Montréal, Québec H1T 2M4 Canada
| | - Guillaume Lettre
- Montreal Heart Institute, 5000 Bélanger Street, Montréal, Québec H1T 1C8 Canada ; Faculté de Médecine, Université de Montréal, 2900 Boul. Édouard-Montpetit, Montréal, Québec H3T 1J4 Canada
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104
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Chiu SC, Chung HY, Cho DY, Chan TM, Liu MC, Huang HM, Li TY, Lin JY, Chou PC, Fu RH, Yang WK, Harn HJ, Lin SZ. Therapeutic potential of microRNA let-7: tumor suppression or impeding normal stemness. Cell Transplant 2015; 23:459-69. [PMID: 24816444 DOI: 10.3727/096368914x678418] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The first microRNA, let-7, and its family were discovered in Caenorhabditis elegans and are functionally conserved from worms to humans in the regulation of embryonic development and stemness. The let-7 family has been shown to have an essential role in stem cell differentiation and tumor-suppressive activity. Deregulating expression of let-7 is commonly reported in many human cancers. Emerging evidence has accumulated and suggests that reestablishment of let-7 in tumor cells is a valuable therapeutic strategy. However, findings reach beyond tumor therapeutics and may impinge on stemness and differentiation of stem cells. In this review, we discuss the role of let-7 in development and differentiation of normal adult stem/progenitor cells and offer a viewpoint of the association between deregulated let-7 expression and tumorigenesis. The regulation of let-7 expression, cancer-relevant let-7 targets, and the application of let-7 are highlighted.
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Affiliation(s)
- Shao-Chih Chiu
- Graduate Institute of Immunology, China Medical University, Taichung, Taiwan
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105
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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: 61] [Impact Index Per Article: 6.8] [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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106
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Nagalakshmi VK, Lindner V, Wessels A, Yu J. microRNA-dependent temporal gene expression in the ureteric bud epithelium during mammalian kidney development. Dev Dyn 2014; 244:444-56. [PMID: 25369991 DOI: 10.1002/dvdy.24221] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2014] [Revised: 10/21/2014] [Accepted: 10/21/2014] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND Our previous study on mouse mutants with the ureteric bud (UB) epithelium-specific Dicer deletion (Dicer UB mutants) demonstrated the significance of UB epithelium-derived miRNAs in UB development. RESULTS Our whole-genome transcriptional profiling showed that the Dicer mutant UB epithelium abnormally retained transcriptional features of the early UB epithelium and failed to express many genes associated with collecting duct differentiation. Furthermore, we identified a temporal expression pattern of early UB genes during UB epithelium development in which gene expression was detected at early developmental stages and became undetectable by embryonic day 14.5. In contrast, expression of early UB genes persisted at later stages in the Dicer mutant UB epithelium and increased at early stages. Our bioinformatic analysis of the abnormally persistently expressed early genes in the Dicer mutant UB epithelium showed significant enrichment of the let-7 family miRNA targets. We further identified a temporal expression pattern of let-7 miRNAs in the UB epithelium that is anti-parallel to that of some early UB genes during kidney development. CONCLUSIONS We propose a model in which the let-7 family miRNAs silence the expression of a subset of early genes in the UB epithelium at later developmental stages to promote collecting duct differentiation. Developmental Dynamics 244:444-456, 2015. © 2014 Wiley Periodicals, Inc.
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Affiliation(s)
- Vidya K Nagalakshmi
- Department of Cell Biology and Child Health Research Center, University of Virginia School of Medicine, Charlottesville, Virginia
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107
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LIN28A expression reduces sickling of cultured human erythrocytes. PLoS One 2014; 9:e106924. [PMID: 25188417 PMCID: PMC4154803 DOI: 10.1371/journal.pone.0106924] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2014] [Accepted: 08/04/2014] [Indexed: 01/23/2023] Open
Abstract
Induction of fetal hemoglobin (HbF) has therapeutic importance for patients with sickle cell disease (SCD) and the beta-thalassemias. It was recently reported that increased expression of LIN28 proteins or decreased expression of its target let-7 miRNAs enhances HbF levels in cultured primary human erythroblasts from adult healthy donors. Here LIN28A effects were studied further using erythrocytes cultured from peripheral blood progenitor cells of pediatric subjects with SCD. Transgenic expression of LIN28A was accomplished by lentiviral transduction in CD34(+) sickle cells cultivated ex vivo in serum-free medium. LIN28A over-expression (LIN28A-OE) increased HbF, reduced beta (sickle)-globin, and strongly suppressed all members of the let-7 family of miRNAs. LIN28A-OE did not affect erythroblast differentiation or prevent enucleation, but it significantly reduced or ameliorated the sickling morphologies of the enucleated erythrocytes.
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108
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Finotti A, Gambari R. Recent trends for novel options in experimental biological therapy of β-thalassemia. Expert Opin Biol Ther 2014; 14:1443-54. [PMID: 24934764 DOI: 10.1517/14712598.2014.927434] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
INTRODUCTION β-thalassemias are caused by nearly 300 mutations of the β-globin gene, leading to low or absent production of adult hemoglobin. Achievements have been recently obtained on innovative therapeutic strategies for β-thalassemias, based on studies focusing on the transcriptional regulation of the γ-globin genes, epigenetic mechanisms governing erythroid differentiation, gene therapy and genetic correction of the mutations. AREAS COVERED The objective of this review is to describe recently published approaches (the review covers the years 2011 - 2014) useful for the development of novel therapeutic strategies for the treatment of β-thalassemia. EXPERT OPINION Modification of β-globin gene expression in β-thalassemia cells was achieved by gene therapy (eventually in combination with induction of fetal hemoglobin [HbF]) and correction of the mutated β-globin gene. Based on recent areas of progress in understanding the control of γ-globin gene expression, novel strategies for inducing HbF have been proposed. Furthermore, the identification of microRNAs involved in erythroid differentiation and HbF production opens novel options for developing therapeutic approaches for β-thalassemia and sickle-cell anemia.
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Affiliation(s)
- Alessia Finotti
- Biotechnology Centre of Ferrara University, Laboratory for the Development of Gene and Pharmacogenomic Therapy of Thalassaemia , Ferrara , Italy
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109
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Emmrich S, Rasche M, Schöning J, Reimer C, Keihani S, Maroz A, Xie Y, Li Z, Schambach A, Reinhardt D, Klusmann JH. miR-99a/100~125b tricistrons regulate hematopoietic stem and progenitor cell homeostasis by shifting the balance between TGFβ and Wnt signaling. Genes Dev 2014; 28:858-74. [PMID: 24736844 PMCID: PMC4003278 DOI: 10.1101/gad.233791.113] [Citation(s) in RCA: 125] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
miR-99a/100, let-7, and miR-125b paralogs are encoded in two tricistrons and are highly expressed in hematopoietic stem cells (HSCs). Emmrich et al. demonstrate that miR-99a/100∼125b tricistrons are transcribed as a polycistronic message and functionally converge at the combinatorial block of the TGFβ pathway. Down-regulating tumor suppressor genes APC/APC2 stabilized active β-catenin and enhanced Wnt signaling. These tricistronic miRNAs promoted sustained expansion of murine and human HSCs by switching the balance between Wnt and TGFβ signaling. Although regulation of stem cell homeostasis by microRNAs (miRNAs) is well studied, it is unclear how individual miRNAs genomically encoded within an organized polycistron can interact to induce an integrated phenotype. miR-99a/100, let-7, and miR-125b paralogs are encoded in two tricistrons on human chromosomes 11 and 21. They are highly expressed in hematopoietic stem cells (HSCs) and acute megakaryoblastic leukemia (AMKL), an aggressive form of leukemia with poor prognosis. Here, we show that miR-99a/100∼125b tricistrons are transcribed as a polycistronic message transactivated by the homeobox transcription factor HOXA10. Integrative analysis of global gene expression profiling, miRNA target prediction, and pathway architecture revealed that miR-99a/100, let-7, and miR-125b functionally converge at the combinatorial block of the transforming growth factor β (TGFβ) pathway by targeting four receptor subunits and two SMAD signaling transducers. In addition, down-regulation of tumor suppressor genes adenomatous polyposis coli (APC)/APC2 stabilizes active β-catenin and enhances Wnt signaling. By switching the balance between Wnt and TGFβ signaling, the concerted action of these tricistronic miRNAs promoted sustained expansion of murine and human HSCs in vitro or in vivo while favoring megakaryocytic differentiation. Hence, our study explains the high phylogenetic conservation of the miR-99a/100∼125b tricistrons controlling stem cell homeostasis, the deregulation of which contributes to the development of AMKL.
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Affiliation(s)
- Stephan Emmrich
- Pediatric Hematology and Oncology, Hannover Medical School, Hannover 30625, Germany
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110
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Copley MR, Eaves CJ. Developmental changes in hematopoietic stem cell properties. Exp Mol Med 2013; 45:e55. [PMID: 24232254 PMCID: PMC3849580 DOI: 10.1038/emm.2013.98] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Accepted: 07/29/2013] [Indexed: 01/18/2023] Open
Abstract
Hematopoietic stem cells (HSCs) comprise a rare population of cells that can regenerate and maintain lifelong blood cell production. This functionality is achieved through their ability to undergo many divisions without activating a poised, but latent, capacity for differentiation into multiple blood cell types. Throughout life, HSCs undergo sequential changes in several key properties. These affect mechanisms that regulate the self-renewal, turnover and differentiation of HSCs as well as the properties of the committed progenitors and terminally differentiated cells derived from them. Recent findings point to the Lin28b-let-7 pathway as a master regulator of many of these changes with important implications for the clinical use of HSCs for marrow rescue and gene therapy, as well as furthering our understanding of the different pathogenesis of childhood and adult-onset leukemia.
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111
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Chang KH, Huang A, Han H, Jiang Y, Fang X, Song CZ, Padilla S, Wang H, Qu H, Stamatoyannopoulos J, Li Q, Papayannopoulou T. Transcriptional environment and chromatin architecture interplay dictates globin expression patterns of heterospecific hybrids derived from undifferentiated human embryonic stem cells or from their erythroid progeny. Exp Hematol 2013; 41:967-979.e6. [PMID: 23993951 PMCID: PMC3836866 DOI: 10.1016/j.exphem.2013.08.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2013] [Accepted: 08/20/2013] [Indexed: 11/21/2022]
Abstract
To explore the response of β globin locus with established chromatin domains upon their exposure to new transcriptional environments, we transferred the chromatin-packaged β globin locus of undifferentiated human embryonic stem cells (hESCs) or hESC-derived erythroblasts into an adult transcriptional environment. Distinct globin expression patterns were observed. In hESC-derived erythroblasts where both ε and γ globin were active and marked by similar chromatin modifications, ε globin was immediately silenced upon transfer, whereas γ globin continued to be expressed for months, implying that different transcriptional environments were required for their continuing expression. Whereas β globin was silent both in hESCs and in hESC-derived erythroblasts, β globin was only activated upon transfer from hESCs, but not in the presence of dominant γ globin transferred from hESC-derived erythroblasts, confirming the competing nature of γ versus β globin expression. With time, however, silencing of γ globin occurred in the adult transcriptional environment with concurrent activation of β-globin, accompanied by a drastic change in the epigenetic landscape of γ and β globin gene regions without apparent changes in the transcriptional environment. This switching process could be manipulated by overexpression or downregulation of certain transcription factors. Our studies provide important insights into the interplay between the transcription environment and existing chromatin domains, and we offer an experimental system to study the time-dependent human globin switching.
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Affiliation(s)
- Kai-Hsin Chang
- Department of Medicine, Division of Hematology, University of Washington, Seattle, WA, 98195, USA
| | - Andy Huang
- Department of Medicine, Division of Hematology, University of Washington, Seattle, WA, 98195, USA
| | - Hemei Han
- Department of Medicine, Division of Medical Genetics, University of Washington, Seattle, WA 98195, USA
| | - Yi Jiang
- Department of Medicine, Division of Hematology, University of Washington, Seattle, WA, 98195, USA
| | - Xiangdong Fang
- Department of Medicine, Division of Medical Genetics, University of Washington, Seattle, WA 98195, USA
- Laboratory of Disease Genomics and Individualized Medicine, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100029, China
| | - Chao-Zhong Song
- Department of Medicine, Division of Medical Genetics, University of Washington, Seattle, WA 98195, USA
| | - Steve Padilla
- Department of Medicine, Division of Hematology, University of Washington, Seattle, WA, 98195, USA
| | - Hao Wang
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
| | - Hongzhu Qu
- Laboratory of Disease Genomics and Individualized Medicine, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100029, China
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
| | | | - Qiliang Li
- Department of Medicine, Division of Medical Genetics, University of Washington, Seattle, WA 98195, USA
| | - Thalia Papayannopoulou
- Department of Medicine, Division of Hematology, University of Washington, Seattle, WA, 98195, USA
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