1
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Simbula M, Manchinu MF, Mingoia M, Pala M, Asunis I, Caria CA, Perseu L, Shah M, Crossley M, Moi P, Ristaldi MS. miR-365-3p mediates BCL11A and SOX6 erythroid-specific coregulation: A new player in HbF activation. MOLECULAR THERAPY. NUCLEIC ACIDS 2023; 34:102025. [PMID: 37744176 PMCID: PMC10514143 DOI: 10.1016/j.omtn.2023.09.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Accepted: 09/01/2023] [Indexed: 09/26/2023]
Abstract
Hemoglobin switching is a complex biological process not yet fully elucidated. The mechanism regulating the suppression of fetal hemoglobin (HbF) expression is of particular interest because of the positive impact of HbF on the course of diseases such as β-thalassemia and sickle cell disease, hereditary hemoglobin disorders that affect the health of countless individuals worldwide. Several transcription factors have been implicated in the control of HbF, of which BCL11A has emerged as a major player in HbF silencing. SOX6 has also been implicated in silencing HbF and is critical to the silencing of the mouse embryonic hemoglobins. BCL11A and SOX6 are co-expressed and physically interact in the erythroid compartment during differentiation. In this study, we observe that BCL11A knockout leads to post-transcriptional downregulation of SOX6 through activation of microRNA (miR)-365-3p. Downregulating SOX6 by transient ectopic expression of miR-365-3p or gene editing activates embryonic and fetal β-like globin gene expression in erythroid cells. The synchronized expression of BCL11A and SOX6 is crucial for hemoglobin switching. In this study, we identified a BCL11A/miR-365-3p/SOX6 evolutionarily conserved pathway, providing insights into the regulation of the embryonic and fetal globin genes suggesting new targets for treating β-hemoglobinopathies.
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Affiliation(s)
- Michela Simbula
- Istituto Di Ricerca Genetica e Biomedica del Consiglio Nazionale Delle Ricerche (IRGB-CNR), 09042 Monserrato, Italy
| | - Maria Francesca Manchinu
- Istituto Di Ricerca Genetica e Biomedica del Consiglio Nazionale Delle Ricerche (IRGB-CNR), 09042 Monserrato, Italy
| | - Maura Mingoia
- Istituto Di Ricerca Genetica e Biomedica del Consiglio Nazionale Delle Ricerche (IRGB-CNR), 09042 Monserrato, Italy
- Dipartimento di Scienze Mediche e Sanità Pubblica, Università degli Studi di Cagliari, 09121 Cagliari, Italy
| | - Mauro Pala
- Istituto Di Ricerca Genetica e Biomedica del Consiglio Nazionale Delle Ricerche (IRGB-CNR), 09042 Monserrato, Italy
| | - Isadora Asunis
- Istituto Di Ricerca Genetica e Biomedica del Consiglio Nazionale Delle Ricerche (IRGB-CNR), 09042 Monserrato, Italy
| | - Cristian Antonio Caria
- Istituto Di Ricerca Genetica e Biomedica del Consiglio Nazionale Delle Ricerche (IRGB-CNR), 09042 Monserrato, Italy
| | - Lucia Perseu
- Istituto Di Ricerca Genetica e Biomedica del Consiglio Nazionale Delle Ricerche (IRGB-CNR), 09042 Monserrato, Italy
| | - Manan Shah
- School of Biotechnology and Biomolecular Sciences, University of New South Wales (UNSW), Sydney, NSW 2052, Australia
| | - Merlin Crossley
- School of Biotechnology and Biomolecular Sciences, University of New South Wales (UNSW), Sydney, NSW 2052, Australia
| | - Paolo Moi
- Istituto Di Ricerca Genetica e Biomedica del Consiglio Nazionale Delle Ricerche (IRGB-CNR), 09042 Monserrato, Italy
- Dipartimento di Scienze Mediche e Sanità Pubblica, Università degli Studi di Cagliari, 09121 Cagliari, Italy
| | - Maria Serafina Ristaldi
- Istituto Di Ricerca Genetica e Biomedica del Consiglio Nazionale Delle Ricerche (IRGB-CNR), 09042 Monserrato, Italy
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2
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Hirano T, Tsuruda T, Tanaka Y, Harada H, Yamazaki T, Ishida A. Long noncoding RNA CCDC26 as a modulator of transcriptional switching between fetal and embryonic globins. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2020; 1868:118931. [PMID: 33340546 DOI: 10.1016/j.bbamcr.2020.118931] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Revised: 12/04/2020] [Accepted: 12/11/2020] [Indexed: 01/04/2023]
Abstract
The CCDC26 gene is considered to encode a functional noncoding RNA associated with acute myeloid leukemia and other cancers. However, investigations into the physiological roles of CCDC26 are rare. Previously, we reported that CCDC26 regulated proliferation and cell death of leukemia cells through KIT, a receptor tyrosine kinase, by using K562 leukemia cells and their derivative CCDC26-knockdown (KD) cells. Here we propose a new role of CCDC26 in the differentiation of erythroid cells. We showed that expression of embryonic (ε- and ζ-) globins was markedly upregulated in CCDC26-KD cells compared with K562 control cells during hemin-induced differentiation. In contrast, expression of fetal-type γ-globin, a major globin expressed in original K562 cells, was decreased. These changes in the expression of globin genes mainly took place at the transcriptional level, with significant suppression of transcription of adult (β-, δ-) globins in CCDC26-KD cells. Re-introduction of exogenous CCDC26 into the CCDC26-KD cells recovered low-level expression of the embryonal globins. These results suggest CCDC26 has a role in switching transcription of globin genes in the differentiation of erythroid cells. The expression profile of the CCDC26-KD cells and control cells suggests FOG-2, a transcriptional modulator, as a candidate for a mediator of the CCDC26-associated regulation. We showed that both embryonic globins were transcriptionally activated in FOG-2-KD K562 cells. The KIT inhibitor ISCK03 suppressed the production of hemoglobin in K562 cells but did not affect transcription of globin genes. To summarize, FOG-2, but not KIT, is responsible for globin transcriptional regulation by CCDC26.
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Affiliation(s)
- Tetsuo Hirano
- Graduate School of Integrated Sciences for Life, Hiroshima University, 1-7-1 Kagamiyama, Higashihiroshima, Hiroshima 739-8521, Japan.
| | - Tomomi Tsuruda
- School of Integrated Arts and Sciences, Hiroshima University, 1-7-1 Kagamiyama, Higashihiroshima, Hiroshima 739-8521, Japan
| | - Yuka Tanaka
- Graduate School of Integrated Sciences for Life, Hiroshima University, 1-7-1 Kagamiyama, Higashihiroshima, Hiroshima 739-8521, Japan
| | - Hironori Harada
- Laboratory of Oncology, School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi, Hachioji, Tokyo 192-0392, Japan.
| | - Takeshi Yamazaki
- Graduate School of Integrated Sciences for Life, Hiroshima University, 1-7-1 Kagamiyama, Higashihiroshima, Hiroshima 739-8521, Japan.
| | - Atsuhiko Ishida
- Graduate School of Integrated Sciences for Life, Hiroshima University, 1-7-1 Kagamiyama, Higashihiroshima, Hiroshima 739-8521, Japan.
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3
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Epsilon-Globin HBE1 Enhances Radiotherapy Resistance by Down-Regulating BCL11A in Colorectal Cancer Cells. Cancers (Basel) 2019; 11:cancers11040498. [PMID: 30965648 PMCID: PMC6521047 DOI: 10.3390/cancers11040498] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Revised: 03/27/2019] [Accepted: 04/02/2019] [Indexed: 12/28/2022] Open
Abstract
Resistance to radiotherapy is considered an important obstacle in the treatment of colorectal cancer. However, the mechanisms that enable tumor cells to tolerate the effects of radiation remain unclear. Moreover, radiotherapy causes accumulated mutations in transcription factors, which can lead to changes in gene expression and radiosensitivity. This phenomenon reduces the effectiveness of radiation therapy towards cancer cells. In the present study, radiation-resistant (RR) cancer cells were established by sequential radiation exposure, and hemoglobin subunit epsilon 1 (HBE1) was identified as a candidate radiation resistance-associated protein based on RNA-sequencing analysis. Then, compared to radiosensitive (RS) cell lines, the overexpression of HBE1 in RR cell lines was used to measure various forms of radiation-induced cellular damage. Consequently, HBE1-overexpressing cell lines were found to exhibit decreased radiation-induced intracellular reactive oxygen species (ROS) production and cell mortality. Conversely, HBE1 deficiency in RR cell lines increased intracellular ROS production, G2/M arrest, and apoptosis, and decreased clonogenic survival rate. These effects were reversed by the ROS scavenger N-acetyl cysteine. Moreover, HBE1 overexpression was found to attenuate radiation-induced endoplasmic reticulum stress and apoptosis via an inositol-requiring enzyme 1(IRE1)-Jun amino-terminal kinase (JNK) signaling pathway. In addition, increased HBE1 expression induced by γ-irradiation in RS cells attenuated expression of the transcriptional regulator BCL11A, whereas its depletion in RR cells increased BCL11A expression. Collectively, these observations indicate that the expression of HBE1 during radiotherapy might potentiate the survival of radiation-exposed colorectal cancer cells.
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Wang Y, Wang Y, Ma L, Nie M, Ju J, Liu M, Deng Y, Yao B, Gui T, Li X, Guo C, Ma C, Tan R, Zhao Q. Heterochromatin Protein 1γ Is a Novel Epigenetic Repressor of Human Embryonic ϵ-Globin Gene Expression. J Biol Chem 2017; 292:4811-4817. [PMID: 28154185 DOI: 10.1074/jbc.m116.768515] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Revised: 01/27/2017] [Indexed: 11/06/2022] Open
Abstract
Production of hemoglobin during development is tightly regulated. For example, expression from the human β-globin gene locus, comprising β-, δ-, ϵ-, and γ-globin genes, switches from ϵ-globin to γ-globin during embryonic development and then from γ-globin to β-globin after birth. Expression of human ϵ-globin in mice has been shown to ameliorate anemia caused by β-globin mutations, including those causing β-thalassemia and sickle cell disease, raising the prospect that reactivation of ϵ-globin expression could be used in managing these conditions in humans. Although the human globin genes are known to be regulated by a variety of multiprotein complexes containing enzymes that catalyze epigenetic modifications, the exact mechanisms controlling ϵ-globin gene silencing remain elusive. Here we found that the heterochromatin protein HP1γ, a multifunctional chromatin- and DNA-binding protein with roles in transcriptional activation and elongation, represses ϵ-globin expression by interacting with a histone-modifying enzyme, lysine methyltransferase SUV4-20h2. Silencing of HP1γ expression markedly decreased repressive histone marks and the multimethylation of histone H3 lysine 9 and H4 lysine 20, leading to a significant decrease in DNA methylation at the proximal promoter of the ϵ-globin gene and greatly increased ϵ-globin expression. In addition, using chromatin immunoprecipitation, we showed that SUV4-20h2 facilitates the deposition of HP1γ on the ϵ-globin-proximal promoter. Thus, these data indicate that HP1γ is a novel epigenetic repressor of ϵ-globin gene expression and provide a potential strategy for targeted therapies for β-thalassemia and sickle cell disease.
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Affiliation(s)
- Yadong Wang
- From the State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing 210023, China
| | - Ying Wang
- From the State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing 210023, China
| | - Lingling Ma
- From the State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing 210023, China
| | - Min Nie
- From the State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing 210023, China
| | - Junyi Ju
- From the State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing 210023, China
| | - Ming Liu
- From the State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing 210023, China
| | - Yexuan Deng
- From the State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing 210023, China
| | - Bing Yao
- From the State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing 210023, China
| | - Tao Gui
- From the State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing 210023, China
| | - Xinyu Li
- From the State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing 210023, China
| | - Chan Guo
- From the State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing 210023, China
| | - Chi Ma
- From the State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing 210023, China
| | - Renxiang Tan
- From the State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing 210023, China
| | - Quan Zhao
- From the State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing 210023, China
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5
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Wang Y, Rank G, Li Z, Wang Y, Ju J, Nuber A, Wu Y, Liu M, Nie M, Huang F, Cerruti L, Ma C, Tan R, Schotta G, Jane SM, Zeng CK, Zhao Q. ε-globin expression is regulated by SUV4-20h1. Haematologica 2016; 101:e168-72. [PMID: 26802048 DOI: 10.3324/haematol.2015.139980] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Affiliation(s)
- Yadong Wang
- The State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, China
| | - Gerhard Rank
- Department of Medicine, Monash University Central Clinical School, Prahran, VIC, Australia
| | - Zhuchen Li
- The State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, China
| | - Ying Wang
- The State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, China
| | - Junyi Ju
- The State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, China
| | - Alexander Nuber
- Biomedical Center and Center for Integrated Protein Science, Ludwig-Maximilians-University, Martinsried, Germany
| | - Yupeng Wu
- The State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, China
| | - Ming Liu
- The State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, China
| | - Min Nie
- The State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, China
| | - Feifei Huang
- The State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, China
| | - Loretta Cerruti
- Department of Medicine, Monash University Central Clinical School, Prahran, VIC, Australia
| | - Chi Ma
- The State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, China
| | - Renxiang Tan
- The State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, China
| | - Gunnar Schotta
- Biomedical Center and Center for Integrated Protein Science, Ludwig-Maximilians-University, Martinsried, Germany
| | - Stephen M Jane
- Department of Medicine, Monash University Central Clinical School, Prahran, VIC, Australia
| | | | - Quan Zhao
- The State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, China
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6
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Safo MK, Ko TP, Abdulmalik O, He Z, Wang AHJ, Schreiter ER, Russell JE. Structure of fully liganded Hb ζ2β2s trapped in a tense conformation. ACTA CRYSTALLOGRAPHICA. SECTION D, BIOLOGICAL CRYSTALLOGRAPHY 2013; 69:2061-71. [PMID: 24100324 PMCID: PMC3792644 DOI: 10.1107/s0907444913019197] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2013] [Accepted: 07/10/2013] [Indexed: 11/10/2022]
Abstract
A variant Hb ζ2β2(s) that is formed from sickle hemoglobin (Hb S; α2β2(s)) by exchanging adult α-globin with embryonic ζ-globin subunits shows promise as a therapeutic agent for sickle-cell disease (SCD). Hb ζ2β2(s) inhibits the polymerization of deoxygenated Hb S in vitro and reverses characteristic features of SCD in vivo in mouse models of the disorder. When compared with either Hb S or with normal human adult Hb A (α2β2), Hb ζ2β2(s) exhibits atypical properties that include a high oxygen affinity, reduced cooperativity, a weak Bohr effect and blunted 2,3-diphosphoglycerate allostery. Here, the 1.95 Å resolution crystal structure of human Hb ζ2β2(s) that was expressed in complex transgenic knockout mice and purified from their erythrocytes is presented. When fully liganded with carbon monoxide, Hb ζ2β2(s) displays a central water cavity, a ζ1-β(s)2 (or ζ2-β(s)1) interface, intersubunit salt-bridge/hydrogen-bond interactions, C-terminal βHis146 salt-bridge interactions, and a β-cleft, that are highly unusual for a relaxed hemoglobin structure and are more typical of a tense conformation. These quaternary tense-like features contrast with the tertiary relaxed-like conformations of the ζ1β(s)1 dimer and the CD and FG corners, as well as the overall structures of the heme cavities. This crystallographic study provides insights into the altered oxygen-transport properties of Hb ζ2β2(s) and, moreover, decouples tertiary- and quaternary-structural events that are critical to Hb ligand binding and allosteric function.
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Affiliation(s)
- Martin K. Safo
- Institute for Structural Biology and Drug Discovery, and the Department of Medicinal Chemistry, School of Pharmacy, Virginia Commonwealth University, Richmond, VA 23298, USA
| | - Tzu-Ping Ko
- Institute of Biological Chemistry, Academia Sinica, Taipei 11529, Taiwan
| | - Osheiza Abdulmalik
- Division of Hematology, The Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Zhenning He
- Division of Hematology–Oncology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Andrew H.-J. Wang
- Institute of Biological Chemistry, Academia Sinica, Taipei 11529, Taiwan
| | - Eric R. Schreiter
- Howard Hughes Medical Institute, Janelia Farm Research Campus, Ashburn, VA 20147, USA
| | - J. Eric Russell
- Division of Hematology, The Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA
- Division of Hematology–Oncology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
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7
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Rupon JW, Wang SZ, Gnanapragasam M, Labropoulos S, Ginder GD. MBD2 contributes to developmental silencing of the human ε-globin gene. Blood Cells Mol Dis 2011; 46:212-9. [PMID: 21296012 DOI: 10.1016/j.bcmd.2011.01.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2010] [Revised: 12/21/2010] [Accepted: 12/30/2010] [Indexed: 11/17/2022]
Abstract
During erythroid development, the embryonic ε-globin gene becomes silenced as erythropoiesis shifts from the yolk sac to the fetal liver where γ-globin gene expression predominates. Previous studies have shown that the ε-globin gene is autonomously silenced through promoter proximal cis-acting sequences in adult erythroid cells. We have shown a role for the methylcytosine binding domain protein 2 (MBD2) in the developmental silencing of the avian embryonic ρ-globin and human fetal γ-globin genes. To determine the roles of MBD2 and DNA methylation in human ε-globin gene silencing, transgenic mice containing all sequences extending from the 5' hypersensitive site 5 (HS5) of the β-globin locus LCR to the human γ-globin gene promoter were generated. These mice show correct developmental expression and autonomous silencing of the transgene. Either the absence of MBD2 or treatment with the DNA methyltransferase inhibitor 5-azacytidine increases ε-globin transgene expression by 15-20 fold in adult mice. Adult mice containing the entire human β-globin locus also show an increase in expression of both the ε-globin gene transgene and endogenous ε(Y) and β(H1) genes in the absence of MBD2. These results indicate that the human ε-globin gene is subject to multilayered silencing mediated in part by MBD2.
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Affiliation(s)
- Jeremy W Rupon
- Massey Cancer Center, Virginia Commonwealth University, Richmond, USA.
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8
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Cohen-Barak O, Erickson DT, Badowski MS, Fuchs DA, Klassen CL, Harris DT, Brilliant MH. Stem cell transplantation demonstrates that Sox6 represses εy globin expression in definitive erythropoiesis of adult mice. Exp Hematol 2007; 35:358-67. [PMID: 17309816 DOI: 10.1016/j.exphem.2006.11.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2006] [Revised: 11/03/2006] [Accepted: 11/16/2006] [Indexed: 11/22/2022]
Abstract
Sox6, a member of the Sox transcription factor family, is essential for the silencing of epsilon y globin gene expression in definitive erythropoiesis of mice. Homozygous Sox6-null mice are neonatally lethal, precluding analysis at later stages. We created adult mice that are deficient in Sox6 specifically in hematopoietic tissues by transplanting embryonic liver stem cells from Sox6-deficient mice into lethally irradiated congenic wild-type adult mice. The mice receiving mutant stem cells (mutant engrafted) showed high expression levels of epsilon y in bone marrow, spleen, and circulating blood compared with mice receiving wild-type and heterozygous stem cells (control engrafted). The level of expression of epsilon y in circulating blood was directly correlated with the percentage of successful mutant donor cell engraftment. Additionally, the mutant engrafted adult mice showed an increase in erythroid precursor cells in bone marrow, spleen, and blood. Thus, Sox6 continues to function as a major regulator of epsilon y in adult definitive erythropoiesis and is required for normal erythrocyte maturation. Therefore, Sox6 may provide a novel therapeutic target by reactivating epsilon y in patients with hemoglobinopathies such as sickle cell anemia and beta-thalassemia.
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Affiliation(s)
- Orit Cohen-Barak
- Department of Pediatrics, University of Arizona, College of Medicine, Tucson, AZ 85724, USA
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9
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Abstract
Functional studies of embryonic epsilon-globin indicate that individuals with beta thalassemia or sickle cell disease are likely to benefit from therapeutic, transcriptional derepression of its encoding gene. The success of epsilon-globin gene-reactivation strategies, however, will be tempered by the stability that epsilon-globin mRNA exhibits in developmental stage-discordant definitive erythroid progenitors. Using cell culture and transgenic mouse model systems, we demonstrate that epsilon-globin mRNA is modestly unstable in immature, transcriptionally active erythroid cells, but that this characteristic has relatively little impact on the accumulation of epsilon-globin mRNA at subsequent stages of terminal differentiation. Importantly, the constitutive stability of epsilon-globin mRNA increases in transgenic mouse models of beta thalassemia, suggesting that epsilon- and beta-globin mRNAs are coregulated through a shared posttranscriptional mechanism. As anticipated, relevant cis-acting determinants of epsilon-globin mRNA stability map to its 3' UTR, consistent with the positioning of functionally related elements in other globin mRNAs. These studies demonstrate that posttranscriptional processes do not pose a significant practical barrier to epsilon-globin gene reactivation and, moreover, indicate that related therapeutic strategies may be particularly effective in individuals carrying beta-thalassemic gene defects.
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Affiliation(s)
- Zhenning He
- Department of Medicine (Hematology-Oncology) and
| | - J. Eric Russell
- Department of Medicine (Hematology-Oncology) and
- Department of Pediatrics (Hematology), University of Pennsylvania School of Medicine, and The Children's Hospital of Philadelphia, PA
- Correspondence: J. Eric Russell,
Abramson Research Building, Rm 316F, The Children's Hospital of Philadelphia, 34th St and Civic Center Blvd, Philadelphia, PA 19104; e-mail:
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10
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Yi Z, Cohen-Barak O, Hagiwara N, Kingsley PD, Fuchs DA, Erickson DT, Epner EM, Palis J, Brilliant MH. Sox6 directly silences epsilon globin expression in definitive erythropoiesis. PLoS Genet 2006; 2:e14. [PMID: 16462943 PMCID: PMC1359074 DOI: 10.1371/journal.pgen.0020014] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2005] [Accepted: 12/20/2005] [Indexed: 11/19/2022] Open
Abstract
Sox6 is a member of the Sox transcription factor family that is defined by the conserved high mobility group (HMG) DNA binding domain, first described in the testis determining gene, Sry. Previous studies have suggested that Sox6 plays a role in the development of the central nervous system, cartilage, and muscle. In the Sox6-deficient mouse, p100H, epsilony globin is persistently expressed, and increased numbers of nucleated red cells are present in the fetal circulation. Transfection assays in GM979 (erythroleukemic) cells define a 36-base pair region of the epsilony proximal promoter that is critical for Sox6 mediated repression. Electrophoretic mobility shift assay (EMSA) and chromatin immunoprecipitation (ChIP) assays demonstrate that Sox6 acts as a repressor by directly binding to the epsilony promoter. The normal expression of Sox6 in wild-type fetal liver and the ectopic expression of epsilony in p100H homozygous fetal liver demonstrate that Sox6 functions in definitive erythropoiesis. The present study shows that Sox6 is required for silencing of epsilony globin in definitive erythropoiesis and suggests a role for Sox6 in erythroid cell maturation. Thus, Sox6 regulation of epsilony globin might provide a novel therapeutical target in the treatment of hemoglobinopathies such as sickle cell anemia and thalassemia.
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Affiliation(s)
- Zanhua Yi
- Department of Pediatrics, University of Arizona, College of Medicine, Tucson, Arizona, United States of America
| | - Orit Cohen-Barak
- Department of Pediatrics, University of Arizona, College of Medicine, Tucson, Arizona, United States of America
| | - Nobuko Hagiwara
- Department of Internal Medicine, Division of Cardiovascular Medicine, University of California Davis, Davis, California, United States of America
| | - Paul D Kingsley
- Department of Pediatrics, Center for Pediatric Biomedical Research, University of Rochester Medical Center, Rochester, New York, United States of America
| | - Deborah A Fuchs
- Department of Pathology, University of Arizona, College of Medicine, Tucson, Arizona, United States of America
| | - Drew T Erickson
- Department of Pediatrics, University of Arizona, College of Medicine, Tucson, Arizona, United States of America
| | - Elliot M Epner
- Department of Hematology & Oncology, Oregon Health & Science University, Portland, Oregon, United States of America
| | - James Palis
- Department of Pediatrics, Center for Pediatric Biomedical Research, University of Rochester Medical Center, Rochester, New York, United States of America
| | - Murray H Brilliant
- Department of Pediatrics, University of Arizona, College of Medicine, Tucson, Arizona, United States of America
- * To whom correspondence should be addressed. E-mail:
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11
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Chen K, Ballas SK, Hantgan RR, Kim-Shapiro DB. Aggregation of normal and sickle hemoglobin in high concentration phosphate buffer. Biophys J 2004; 87:4113-21. [PMID: 15465861 PMCID: PMC1304920 DOI: 10.1529/biophysj.104.046482] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Sickle cell disease is caused by a mutant form of hemoglobin, hemoglobin S, that polymerizes under hypoxic conditions. The extent and mechanism of polymerization are thus the subject of many studies of the pathophysiology of the disease and potential treatment strategies. To facilitate such studies, a model system using high concentration phosphate buffer (1.5 M-1.8 M) has been developed. To properly interpret results from studies using this model it is important to understand the similarities and differences in hemoglobin S polymerization in the model compared to polymerization under physiological conditions. In this article, we show that hemoglobin S and normal adult hemoglobin, hemoglobin A, aggregate in high concentration phosphate buffer even when the concentration of hemoglobin is below the solubility defined for polymerization. This phenomenon was not observed using 0.05 M phosphate buffer or in another model system we studied that uses dextran to enhance polymerization. We have used static light scattering, dynamic light scattering, and differential interference contrast microscopy to confirm aggregation of deoxygenated and oxygenated hemoglobins below their solubility and have shown that this aggregation is not observable using turbidity measurements, a common technique for assessing polymerization. We have also shown that the aggregation increases with increasing temperature in the range of 15 degrees -37 degrees C and that it increases as the concentration of phosphate increases. These studies contribute to the working knowledge of how to properly apply studies of hemoglobin S polymerization that are conducted using the high phosphate model.
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Affiliation(s)
- Kejing Chen
- Department of Physics, Wake Forest University, Winston-Salem, North Carolina, USA
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Abstract
The past 3 years have been characterized by a number of impressive advances as well as setbacks in gene therapy for genetic disease. Children with X-linked severe combined immunodeficiency disorder (SCID-X1) have shown almost complete reconstitution of their immune system after receiving retrovirally transduced autologous CD34+ hematopoietic stem cells (HSCs). However, two of 11 treated patients subsequently developed a leukemia-like disease probablydue to the undesired activation of an oncogene. Gene transfer to HSCs resulted in substantial correction of immune function and multi-lineage engraftment in two patients with adenosine deaminase (ADA)-SCID. Several Phase I clinical trials for treatment of hemophilia A and B have been initiated or completed. Partial correction of hemophilia A, albeit transient, has been reported by ex vivo gene transfer to autologous fibroblasts. Intramuscular injection of adeno-associated viral (AAV) vector to patients with severe hemophilia B resulted in evidence of Factor IX gene transfer to skeletal muscle and a separate trial based on hepatic infusion of AAV vector is ongoing. Sustained therapeutic levels of coagulation factor expression have been achieved in preclinical models using retroviral, lentiviral, AAV and high capacity adenoviral vectors. Efficient lentiviral gene transfer to HSC in murine models of beta-thalassemia and sickle cell disease demonstrated sustained phenotypic correction.
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Affiliation(s)
- Roland W Herzog
- The Children's Hospital of Philadelphia, Abramson Research Center, PA 19104, USA.
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