1
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Sharma A, Mistriel-Zerbib S, Najar RA, Engal E, Bentata M, Taqatqa N, Dahan S, Cohen K, Jaffe-Herman S, Geminder O, Baker M, Nevo Y, Plaschkes I, Kay G, Drier Y, Berger M, Salton M. Isoforms of the TAL1 transcription factor have different roles in hematopoiesis and cell growth. PLoS Biol 2023; 21:e3002175. [PMID: 37379322 DOI: 10.1371/journal.pbio.3002175] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Accepted: 05/30/2023] [Indexed: 06/30/2023] Open
Abstract
T-cell acute lymphoblastic leukemia (T-ALL) protein 1 (TAL1) is a central transcription factor in hematopoiesis. The timing and level of TAL1 expression orchestrate the differentiation to specialized blood cells and its overexpression is a common cause of T-ALL. Here, we studied the 2 protein isoforms of TAL1, short and long, which are generated by the use of alternative promoters as well as by alternative splicing. We analyzed the expression of each isoform by deleting an enhancer or insulator, or by opening chromatin at the enhancer location. Our results show that each enhancer promotes expression from a specific TAL1 promoter. Expression from a specific promoter gives rise to a unique 5' UTR with differential regulation of translation. Moreover, our study suggests that the enhancers regulate TAL1 exon 3 alternative splicing by inducing changes in the chromatin at the splice site, which we demonstrate is mediated by KMT2B. Furthermore, our results indicate that TAL1-short binds more strongly to TAL1 E-protein partners and functions as a stronger transcription factor than TAL1-long. Specifically TAL1-short has a unique transcription signature promoting apoptosis. Finally, when we expressed both isoforms in mice bone marrow, we found that while overexpression of both isoforms prevents lymphoid differentiation, expression of TAL-short alone leads to hematopoietic stem cell exhaustion. Furthermore, we found that TAL1-short promoted erythropoiesis and reduced cell survival in the CML cell line K562. While TAL1 and its partners are considered promising therapeutic targets in the treatment of T-ALL, our results show that TAL1-short could act as a tumor suppressor and suggest that altering TAL1 isoform's ratio could be a preferred therapeutic approach.
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Affiliation(s)
- Aveksha Sharma
- Faculty of Medicine, Department of Biochemistry and Molecular Biology, The Institute for Medical Research Israel-Canada, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Shani Mistriel-Zerbib
- Faculty of Medicine, The Lautenberg Center for Immunology and Cancer Research, The Institute for Medical Research Israel-Canada, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Rauf Ahmad Najar
- Faculty of Medicine, Department of Biochemistry and Molecular Biology, The Institute for Medical Research Israel-Canada, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Eden Engal
- Faculty of Medicine, Department of Biochemistry and Molecular Biology, The Institute for Medical Research Israel-Canada, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Mercedes Bentata
- Faculty of Medicine, Department of Biochemistry and Molecular Biology, The Institute for Medical Research Israel-Canada, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Nadeen Taqatqa
- Faculty of Medicine, Department of Biochemistry and Molecular Biology, The Institute for Medical Research Israel-Canada, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Sara Dahan
- Faculty of Medicine, Department of Biochemistry and Molecular Biology, The Institute for Medical Research Israel-Canada, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Klil Cohen
- Faculty of Medicine, Department of Biochemistry and Molecular Biology, The Institute for Medical Research Israel-Canada, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Shiri Jaffe-Herman
- Faculty of Medicine, Department of Biochemistry and Molecular Biology, The Institute for Medical Research Israel-Canada, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Ophir Geminder
- Faculty of Medicine, Department of Biochemistry and Molecular Biology, The Institute for Medical Research Israel-Canada, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Mai Baker
- Faculty of Medicine, Department of Biochemistry and Molecular Biology, The Institute for Medical Research Israel-Canada, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Yuval Nevo
- Info-CORE, Bioinformatics Unit of the I-CORE Computation Center, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Inbar Plaschkes
- Info-CORE, Bioinformatics Unit of the I-CORE Computation Center, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Gillian Kay
- Faculty of Medicine, Department of Biochemistry and Molecular Biology, The Institute for Medical Research Israel-Canada, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Yotam Drier
- Faculty of Medicine, The Lautenberg Center for Immunology and Cancer Research, The Institute for Medical Research Israel-Canada, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Michael Berger
- Faculty of Medicine, The Lautenberg Center for Immunology and Cancer Research, The Institute for Medical Research Israel-Canada, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Maayan Salton
- Faculty of Medicine, Department of Biochemistry and Molecular Biology, The Institute for Medical Research Israel-Canada, The Hebrew University of Jerusalem, Jerusalem, Israel
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2
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Chuang CK, Chen SF, Su YH, Chen WH, Lin WM, Wang IC, Shyue SK. The Role of SCL Isoforms in Embryonic Hematopoiesis. Int J Mol Sci 2023; 24:ijms24076427. [PMID: 37047400 PMCID: PMC10094407 DOI: 10.3390/ijms24076427] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Revised: 03/16/2023] [Accepted: 03/26/2023] [Indexed: 04/01/2023] Open
Abstract
Three waves of hematopoiesis occur in the mouse embryo. The primitive hematopoiesis appears as blood islands in the extra embryonic yolk sac at E7.5. The extra embryonic pro-definitive hematopoiesis launches in late E8 and the embryonic definitive one turns on at E10.5 indicated by the emergence of hemogenic endothelial cells on the inner wall of the extra embryonic arteries and the embryonic aorta. To study the roles of SCL protein isoforms in murine hematopoiesis, the SCL-large (SCL-L) isoform was selectively destroyed with the remaining SCL-small (SCL-S) isoform intact. It was demonstrated that SCL-S was specifically expressed in the hemogenic endothelial cells (HECs) and SCL-L was only detected in the dispersed cells after budding from HECs. The SCLΔ/Δ homozygous mutant embryos only survived to E10.5 with normal extra embryonic vessels and red blood cells. In wild-type mouse embryos, a layer of neatly aligned CD34+ and CD43+ cells appeared on the endothelial wall of the aorta of the E10.5 fetus. However, the cells at the same site expressed CD31 rather than CD34 and/or CD43 in the E10.5 SCLΔ/Δ embryo, indicating that only the endothelial lineage was developed. These results reveal that the SCL-S is sufficient to sustain the primitive hematopoiesis and SCL-L is necessary to launch the definitive hematopoiesis.
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3
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Siegwart LC, Schwemmers S, Wehrle J, Koellerer C, Seeger T, Gründer A, Pahl HL. The transcription factor NFE2 enhances expression of the hematopoietic master regulators SCL/TAL1 and GATA2. Exp Hematol 2020; 87:42-47.e1. [PMID: 32593672 DOI: 10.1016/j.exphem.2020.06.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Accepted: 06/11/2020] [Indexed: 12/17/2022]
Abstract
Activity of the transcription factor NFE2 is elevated in the majority of patients with myeloproliferative neoplasms (MPNs), either by overexpression of the wild-type alleles or by the presence of an activating mutation. In murine models, enhanced NFE2 activity causes an MPN phenotype with spontaneous transformation to acute leukemia. However, little is known about the downstream target genes activated by augmented NFE2 levels. Here, we describe that NFE2 regulates expression of the hematopoietic master regulators GATA2 and SCL/TAL1, which are in turn overexpressed in primary MPN cells, suggesting that concomitant aberrant activation of several transcription factors coordinately contributes to the cellular expansion characteristic of these disorders.
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Affiliation(s)
- Laura C Siegwart
- Division of Molecular Hematology, Department of Internal Medicine, Hematology/Oncology, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Sven Schwemmers
- Division of Molecular Hematology, Department of Internal Medicine, Hematology/Oncology, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Julius Wehrle
- Division of Molecular Hematology, Department of Internal Medicine, Hematology/Oncology, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Christoph Koellerer
- Division of Molecular Hematology, Department of Internal Medicine, Hematology/Oncology, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Thalia Seeger
- Division of Molecular Hematology, Department of Internal Medicine, Hematology/Oncology, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Albert Gründer
- Division of Molecular Hematology, Department of Internal Medicine, Hematology/Oncology, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Heike L Pahl
- Division of Molecular Hematology, Department of Internal Medicine, Hematology/Oncology, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany.
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4
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Daniel MG, Sachs D, Bernitz JM, Fstkchyan Y, Rapp K, Satija N, Law K, Patel F, Gomes AM, Kim HS, Pereira CF, Chen B, Lemischka IR, Moore KA. Induction of human hemogenesis in adult fibroblasts by defined factors and hematopoietic coculture. FEBS Lett 2019; 593:3266-3287. [PMID: 31557312 DOI: 10.1002/1873-3468.13621] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2019] [Revised: 09/20/2019] [Accepted: 09/23/2019] [Indexed: 12/13/2022]
Abstract
Transcription factor (TF)-based reprogramming of somatic tissues holds great promise for regenerative medicine. Previously, we demonstrated that the TFs GATA2, GFI1B, and FOS convert mouse and human fibroblasts to hemogenic endothelial-like precursors that generate hematopoietic stem progenitor (HSPC)-like cells over time. This conversion is lacking in robustness both in yield and biological function. Herein, we show that inclusion of GFI1 to the reprogramming cocktail significantly expands the HSPC-like population. AFT024 coculture imparts functional potential to these cells and allows quantification of stem cell frequency. Altogether, we demonstrate an improved human hemogenic induction protocol that could provide a valuable human in vitro model of hematopoiesis for disease modeling and a platform for cell-based therapeutics. DATABASE: Gene expression data are available in the Gene Expression Omnibus (GEO) database under the accession number GSE130361.
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Affiliation(s)
- Michael G Daniel
- Department of Cell, Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, NY, USA.,Black Family Stem Cell Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA.,The Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - David Sachs
- Department of Cell, Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, NY, USA.,Black Family Stem Cell Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA.,The Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Jeffrey M Bernitz
- Department of Biosystems Science and Engineering, Eidgenössische Technische Hochschule Zurich, Basel, Switzerland
| | - Yesai Fstkchyan
- Department of Cell, Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, NY, USA.,The Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Katrina Rapp
- Department of Cell, Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, NY, USA.,Black Family Stem Cell Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Namita Satija
- Division of Infectious Disease, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY, USA.,Immunology Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Kenneth Law
- Rocket Pharmaceuticals Ltd, New York, NY, USA
| | - Foram Patel
- Division of Infectious Disease, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY, USA.,Immunology Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Andreia M Gomes
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra, Cantanhede, Portugal
| | - Huen-Suk Kim
- Department of Cell, Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, NY, USA.,Black Family Stem Cell Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA.,The Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Carlos-Filipe Pereira
- Division of Molecular Medicine and Gene Therapy, Lund University, Sweden.,Wallenberg Center for Molecular Medicine, Lund University, Sweden
| | - Benjamin Chen
- Division of Infectious Disease, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY, USA.,Immunology Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Ihor R Lemischka
- Department of Cell, Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, NY, USA.,Black Family Stem Cell Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA.,Department of Pharmacology and Systems Therapeutics, Icahn School of Medicine, New York, NY, USA
| | - Kateri A Moore
- Department of Cell, Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, NY, USA.,Black Family Stem Cell Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
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5
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Rothenberg EV. Causal Gene Regulatory Network Modeling and Genomics: Second-Generation Challenges. J Comput Biol 2019; 26:703-718. [PMID: 31063008 DOI: 10.1089/cmb.2019.0098] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Gene regulatory network modeling has played a major role in advancing the understanding of developmental systems, by crystallizing structures of relevant extant information, by formally posing hypothetical functional relationships between network elements, and by offering clear predictive tests to improve understanding of the mechanisms driving developmental progression. Both ordinary differential equation (ODE)-based and Boolean models have also been highly successful in explaining dynamics within subcircuits of more complex processes. In a very small number of cases, gene regulatory network models of much more global scope have been proposed that successfully predict the dynamics of the processes establishing most of an embryonic body plan. Can such successes be expanded to very different developmental systems, including post-embryonic mammalian systems? This perspective discusses several problems that must be solved in more quantitative and predictive theoretical terms, to make this possible. These problems include: the effects of cellular history on chromatin state and how these affect gene accessibility; the dose dependence of activities of many transcription factors (a problem for Boolean models); stochasticity of some transcriptional outputs (a problem for simple ODE models); response timing delays due to epigenetic remodeling requirements; functionally different kinds of repression; and the regulatory syntax that governs responses of genes with multiple enhancers.
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Affiliation(s)
- Ellen V Rothenberg
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California
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6
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Deregulated hedgehog pathway signaling is inhibited by the smoothened antagonist LDE225 (Sonidegib) in chronic phase chronic myeloid leukaemia. Sci Rep 2016; 6:25476. [PMID: 27157927 PMCID: PMC4860619 DOI: 10.1038/srep25476] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Accepted: 04/18/2016] [Indexed: 02/06/2023] Open
Abstract
Targeting the Hedgehog (Hh) pathway represents a potential leukaemia stem cell (LSC)-directed therapy which may compliment tyrosine kinase inhibitors (TKIs) to eradicate LSC in chronic phase (CP) chronic myeloid leukaemia (CML). We set out to elucidate the role of Hh signaling in CP-CML and determine if inhibition of Hh signaling, through inhibition of smoothened (SMO), was an effective strategy to target CP-CML LSC. Assessment of Hh pathway gene and protein expression demonstrated that the Hh pathway is activated in CD34+ CP-CML stem/progenitor cells. LDE225 (Sonidegib), a small molecule, clinically investigated SMO inhibitor, used alone and in combination with nilotinib, inhibited the Hh pathway in CD34+ CP-CML cells, reducing the number and self-renewal capacity of CML LSC in vitro. The combination had no effect on normal haemopoietic stem cells. When combined, LDE225 + nilotinib reduced CD34+ CP-CML cell engraftment in NSG mice and, upon administration to EGFP+ /SCLtTA/TRE-BCR-ABL mice, the combination enhanced survival with reduced leukaemia development in secondary transplant recipients. In conclusion, the Hh pathway is deregulated in CML stem and progenitor cells. We identify Hh pathway inhibition, in combination with nilotinib, as a potentially effective therapeutic strategy to improve responses in CP-CML by targeting both stem and progenitor cells.
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7
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Sive JI, Göttgens B. Transcriptional network control of normal and leukaemic haematopoiesis. Exp Cell Res 2014; 329:255-64. [PMID: 25014893 PMCID: PMC4261078 DOI: 10.1016/j.yexcr.2014.06.021] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2014] [Revised: 06/26/2014] [Accepted: 06/28/2014] [Indexed: 12/23/2022]
Abstract
Transcription factors (TFs) play a key role in determining the gene expression profiles of stem/progenitor cells, and defining their potential to differentiate into mature cell lineages. TF interactions within gene-regulatory networks are vital to these processes, and dysregulation of these networks by TF overexpression, deletion or abnormal gene fusions have been shown to cause malignancy. While investigation of these processes remains a challenge, advances in genome-wide technologies and growing interactions between laboratory and computational science are starting to produce increasingly accurate network models. The haematopoietic system provides an attractive experimental system to elucidate gene regulatory mechanisms, and allows experimental investigation of both normal and dysregulated networks. In this review we examine the principles of TF-controlled gene regulatory networks and the key experimental techniques used to investigate them. We look in detail at examples of how these approaches can be used to dissect out the regulatory mechanisms controlling normal haematopoiesis, as well as the dysregulated networks associated with haematological malignancies.
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Affiliation(s)
- Jonathan I Sive
- Department of Haematology, Cambridge Institute for Medical Research and Wellcome Trust and MRC Cambridge Stem Cell Institute, University of Cambridge, Cambridge, UK.
| | - Berthold Göttgens
- Department of Haematology, Cambridge Institute for Medical Research and Wellcome Trust and MRC Cambridge Stem Cell Institute, University of Cambridge, Cambridge, UK.
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8
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Impaired in vitro erythropoiesis following deletion of the Scl (Tal1) +40 enhancer is largely compensated for in vivo despite a significant reduction in expression. Mol Cell Biol 2013; 33:1254-66. [PMID: 23319051 DOI: 10.1128/mcb.01525-12] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
The Scl (Tal1) gene encodes a helix-loop-helix transcription factor essential for hematopoietic stem cell and erythroid development. The Scl +40 enhancer is situated downstream of Map17, the 3' flanking gene of Scl, and is active in transgenic mice during primitive and definitive erythropoiesis. To analyze the in vivo function of the Scl +40 enhancer within the Scl/Map17 transcriptional domain, we deleted this element in the germ line. Scl(Δ40/Δ40) mice were viable with reduced numbers of erythroid CFU in both bone marrow and spleen yet displayed a normal response to stress hematopoiesis. Analysis of Scl(Δ40/Δ40) embryonic stem (ES) cells revealed impaired erythroid differentiation, which was accompanied by a failure to upregulate Scl when erythropoiesis was initiated. Map17 expression was also reduced in hematopoietic tissues and differentiating ES cells, and the Scl +40 element was able to enhance activity of the Map17 promoter. However, only Scl but not Map17 could rescue the Scl(Δ40/Δ40) ES phenotype. Together, these data demonstrate that the Scl +40 enhancer is an erythroid cell-specific enhancer that regulates the expression of both Scl and Map17. Moreover, deletion of the +40 enhancer causes a novel erythroid phenotype, which can be rescued by ectopic expression of Scl but not Map17.
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9
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Rogers H, Wang L, Yu X, Alnaeeli M, Cui K, Zhao K, Bieker JJ, Prchal J, Huang S, Weksler B, Noguchi CT. T-cell acute leukemia 1 (TAL1) regulation of erythropoietin receptor and association with excessive erythrocytosis. J Biol Chem 2012; 287:36720-31. [PMID: 22982397 DOI: 10.1074/jbc.m112.378398] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
During erythropoiesis, erythropoietin stimulates induction of erythroid transcription factors that activate expression of erythroid genes including the erythropoietin receptor (EPO-R) that results in increased sensitivity to erythropoietin. DNA binding of the basic helix-loop-helix transcription factor, TAL1/SCL, is required for normal erythropoiesis. A link between elevated TAL1 and excessive erythrocytosis is suggested by erythroid progenitor cells from a patient that exhibits unusually high sensitivity to erythropoietin with concomitantly elevated TAL1 and EPO-R expression. We found that TAL1 regulates EPO-R expression mediated via three conserved E-box binding motifs (CAGCTG) in the EPO-R 5' untranslated transcribed region. TAL1 increases association of the GATA-1·TAL1·LMO2·LDB1 transcription activation complex to the region that includes the transcription start site and the 5' GATA and 3' E-box motifs flanking the EPO-R transcription start site suggesting that TAL1 promotes accessibility of this region. Nucleosome shifting has been demonstrated to facilitate TAL1 but not GATA-1 binding to regulate target gene expression. Accordingly, we observed that with induced expression of EPO-R in hemotopoietic progenitor cells, nucleosome phasing shifts to increase the linker region containing the EPO-R transcription start site and TAL1 binds to the flanking 5' GATA and 3' E-box regions of the promoter. These data suggest that TAL1 binds to the EPO-R promoter to activate EPO-R expression and provides a potential link to elevated EPO-R expression leading to hypersensitivity to erythropoietin and the resultant excessive erythrocytosis.
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Affiliation(s)
- Heather Rogers
- Molecular Medicine Branch, NIDDK, National Institutes of Health, Bethesda, Maryland 20892-1822, USA
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10
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Smith AM, Sanchez MJ, Follows GA, Kinston S, Donaldson IJ, Green AR, Göttgens B. A novel mode of enhancer evolution: the Tal1 stem cell enhancer recruited a MIR element to specifically boost its activity. Genome Res 2008; 18:1422-32. [PMID: 18687876 PMCID: PMC2527711 DOI: 10.1101/gr.077008.108] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Altered cis-regulation is thought to underpin much of metazoan evolution, yet the underlying mechanisms remain largely obscure. The stem cell leukemia TAL1 (also known as SCL) transcription factor is essential for the normal development of blood stem cells and we have previously shown that the Tal1 +19 enhancer directs expression to hematopoietic stem cells, hematopoietic progenitors, and to endothelium. Here we demonstrate that an adjacent region 1 kb upstream (+18 element) is in an open chromatin configuration and carries active histone marks but does not function as an enhancer in transgenic mice. Instead, it boosts activity of the +19 enhancer both in stable transfection assays and during differentiation of embryonic stem (ES) cells carrying single-copy reporter constructs targeted to the Hprt locus. The +18 element contains a mammalian interspersed repeat (MIR) which is essential for the +18 function and which was transposed to the Tal1 locus approximately 160 million years ago at the time of the mammalian/marsupial branchpoint. Our data demonstrate a previously unrecognized mechanism whereby enhancer activity is modulated by a transposon exerting a "booster" function which would go undetected by conventional transgenic approaches.
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Affiliation(s)
- Aileen M Smith
- University of Cambridge Department of Haematology, Cambridge Institute for Medical Research, Cambridge CB2 2XY, United Kingdom
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11
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Chen X, Blanchette M. Prediction of tissue-specific cis-regulatory modules using Bayesian networks and regression trees. BMC Bioinformatics 2007; 8 Suppl 10:S2. [PMID: 18269696 PMCID: PMC2230503 DOI: 10.1186/1471-2105-8-s10-s2] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
BACKGROUND In vertebrates, a large part of gene transcriptional regulation is operated by cis-regulatory modules. These modules are believed to be regulating much of the tissue-specificity of gene expression. RESULT We develop a Bayesian network approach for identifying cis-regulatory modules likely to regulate tissue-specific expression. The network integrates predicted transcription factor binding site information, transcription factor expression data, and target gene expression data. At its core is a regression tree modeling the effect of combinations of transcription factors bound to a module. A new unsupervised EM-like algorithm is developed to learn the parameters of the network, including the regression tree structure. CONCLUSION Our approach is shown to accurately identify known human liver and erythroid-specific modules. When applied to the prediction of tissue-specific modules in 10 different tissues, the network predicts a number of important transcription factor combinations whose concerted binding is associated to specific expression.
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Affiliation(s)
- Xiaoyu Chen
- McGill Centre for Bioinformatics. 3775 University Street, room 332, Montreal, Quebec, Canada, H3A 2B4,Department of Computer Science and Engineering, University of Washington, Seattle, WA 98105, USA
| | - Mathieu Blanchette
- McGill Centre for Bioinformatics. 3775 University Street, room 332, Montreal, Quebec, Canada, H3A 2B4
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12
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Qian F, Zhen F, Xu J, Huang M, Li W, Wen Z. Distinct functions for different scl isoforms in zebrafish primitive and definitive hematopoiesis. PLoS Biol 2007; 5:e132. [PMID: 17472439 PMCID: PMC1858710 DOI: 10.1371/journal.pbio.0050132] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2006] [Accepted: 03/12/2007] [Indexed: 01/20/2023] Open
Abstract
The stem-cell leukemia (SCL, also known as TAL1) gene encodes a basic helix-loop-helix transcription factor that is essential for the initiation of primitive and definitive hematopoiesis, erythrocyte and megakarocyte differentiation, angiogenesis, and astrocyte development. Here we report that the zebrafish produces, through an alternative promoter site, a novel truncated scl (tal1) isoform, scl-beta, which manifests a temporal and spatial expression distinct from the previously described full-length scl-alpha. Functional analysis reveals that while scl-alpha and -beta are redundant for the initiation of primitive hematopoiesis, these two isoforms exert distinct functions in the regulation of primitive erythroid differentiation and definitive hematopoietic stem cell specification. We further demonstrate that differences in the protein expression levels of scl-alpha and -beta, by regulating their protein stability, are likely to give rise to their distinct functions. Our findings suggest that hematopoietic cells at different levels of hierarchy are likely governed by a gradient of the Scl protein established through temporal and spatial patterns of expression of the different isoforms.
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Affiliation(s)
- Feng Qian
- Laboratory of Molecular and Developmental Immunology, Institute of Molecular and Cell Biology, Singapore, Singapore
| | - Fenghua Zhen
- Laboratory of Molecular and Developmental Immunology, Institute of Molecular and Cell Biology, Singapore, Singapore
- Department of Biological Sciences National University of Singapore, Singapore, Singapore
| | - Jin Xu
- Laboratory of Molecular and Developmental Immunology, Institute of Molecular and Cell Biology, Singapore, Singapore
- Department of Biological Sciences National University of Singapore, Singapore, Singapore
| | - Mei Huang
- Laboratory of Molecular and Developmental Immunology, Institute of Molecular and Cell Biology, Singapore, Singapore
| | - Wanyu Li
- Laboratory of Molecular and Developmental Immunology, Institute of Molecular and Cell Biology, Singapore, Singapore
| | - Zilong Wen
- Laboratory of Molecular and Developmental Immunology, Institute of Molecular and Cell Biology, Singapore, Singapore
- Department of Biological Sciences National University of Singapore, Singapore, Singapore
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13
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Follows GA, Janes ME, Vallier L, Green AR, Gottgens B. Real-time PCR mapping of DNaseI-hypersensitive sites using a novel ligation-mediated amplification technique. Nucleic Acids Res 2007; 35:e56. [PMID: 17389645 PMCID: PMC1885650 DOI: 10.1093/nar/gkm108] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Mapping sites within the genome that are hypersensitive to digestion with DNaseI is an important method for identifying DNA elements that regulate transcription. The standard approach to locating these DNaseI-hypersensitive sites (DHSs) has been to use Southern blotting techniques, although we, and others, have recently published alternative methods using a range of technologies including high-throughput sequencing and genomic array tiling paths. In this article, we describe a novel protocol to use real-time PCR to map DHS. Advantages of the technique reported here include the small cell numbers required for each analysis, rapid, relatively low-cost experiments with minimal need for specialist equipment. Presented examples include comparative DHS mapping of known TAL1/SCL regulatory elements between human embryonic stem cells and K562 cells.
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Affiliation(s)
- George A Follows
- Department of Haematology, Cambridge Institute for Medical Research, Addenbrooke's Hospital, University of Cambridge, Cambridge CB2 2XY, UK.
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14
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Lugus JJ, Chung YS, Mills JC, Kim SI, Grass J, Kyba M, Doherty JM, Bresnick EH, Choi K. GATA2 functions at multiple steps in hemangioblast development and differentiation. Development 2006; 134:393-405. [PMID: 17166922 DOI: 10.1242/dev.02731] [Citation(s) in RCA: 132] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Molecular mechanisms that regulate the generation of hematopoietic and endothelial cells from mesoderm are poorly understood. To define the underlying mechanisms, we compared gene expression profiles between embryonic stem (ES) cell-derived hemangioblasts (Blast-Colony-Forming Cells, BL-CFCs) and their differentiated progeny, Blast cells. Bioinformatic analysis indicated that BL-CFCs resembled other stem cell populations. A role for Gata2, one of the BL-CFC-enriched transcripts, was further characterized by utilizing the in vitro model of ES cell differentiation. Our studies revealed that Gata2 was a direct target of BMP4 and that enforced GATA2 expression upregulated Bmp4, Flk1 and Scl. Conditional GATA2 induction resulted in a temporal-sensitive increase in hemangioblast generation, precocious commitment to erythroid fate, and increased endothelial cell generation. GATA2 additionally conferred a proliferative signal to primitive erythroid progenitors. Collectively, we provide compelling evidence that GATA2 plays specific, contextual roles in the generation of Flk-1+ mesoderm, the Flk-1+Scl+ hemangioblast, primitive erythroid and endothelial cells.
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Affiliation(s)
- Jesse J Lugus
- Department of Pathology and Immunology, Washington University School of Medicine, St Louis, MO 63110, USA
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15
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Follows GA, Dhami P, Göttgens B, Bruce AW, Campbell PJ, Dillon SC, Smith AM, Koch C, Donaldson IJ, Scott MA, Dunham I, Janes ME, Vetrie D, Green AR. Identifying gene regulatory elements by genomic microarray mapping of DNaseI hypersensitive sites. Genome Res 2006; 16:1310-9. [PMID: 16963707 PMCID: PMC1581440 DOI: 10.1101/gr.5373606] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The identification of cis-regulatory elements is central to understanding gene transcription. Hypersensitivity of cis-regulatory elements to digestion with DNaseI remains the gold-standard approach to locating such elements. Traditional methods used to identify DNaseI hypersensitive sites are cumbersome and can only be applied to short stretches of DNA at defined locations. Here we report the development of a novel genomic array-based approach to DNaseI hypersensitive site mapping (ADHM) that permits precise, large-scale identification of such sites from as few as 5 million cells. Using ADHM we identified all previously recognized hematopoietic regulatory elements across 200 kb of the mouse T-cell acute lymphocytic leukemia-1 (Tal1) locus, and, in addition, identified two novel elements within the locus, which show transcriptional regulatory activity. We further validated the ADHM protocol by mapping the DNaseI hypersensitive sites across 250 kb of the human TAL1 locus in CD34+ primary stem/progenitor cells and K562 cells and by mapping the previously known DNaseI hypersensitive sites across 240 kb of the human alpha-globin locus in K562 cells. ADHM provides a powerful approach to identifying DNaseI hypersensitive sites across large genomic regions.
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Affiliation(s)
- George A Follows
- Department of Haematology, Cambridge Institute for Medical Research, University of Cambridge, Cambridge, CB2 2XY, United Kingdom.
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16
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Zhu H, Traver D, Davidson AJ, Dibiase A, Thisse C, Thisse B, Nimer S, Zon LI. Regulation of the lmo2 promoter during hematopoietic and vascular development in zebrafish. Dev Biol 2006; 281:256-69. [PMID: 15893977 DOI: 10.1016/j.ydbio.2005.01.034] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2004] [Revised: 01/04/2005] [Accepted: 01/05/2005] [Indexed: 01/01/2023]
Abstract
The Lmo2 transcription factor, a T-cell oncoprotein, is required for both hematopoiesis and angiogenesis. To investigate the fate of lmo2-expressing cells and the transcriptional regulation of lmo2 in vivo, we generated stable transgenic zebrafish that express green fluorescent protein (EGFP) or DsRed under the control of an lmo2 promoter. A 2.5-kb fragment contains the cis-regulatory elements required to recapitulate endogenous lmo2 expression in embryonic hematopoietic and vascular tissues. We further characterized embryonic Lmo2+ cells through transplantation into vlad tepes (vlt), an erythropoietic mutant. These Lmo2+ primitive wave donor cells differentiated into circulating hematopoietic cells and extended the life span of vlt recipients, but did not demonstrate long-term repopulation of the erythroid lineage. Promoter analysis identified a 174-bp proximal promoter that was sufficient to recapitulate lmo2 expression. This element contains critical ETS-binding sites conserved between zebrafish and pufferfish. Furthermore, we show that ets1 is coexpressed with lmo2, and overexpression experiments indicate that ets1 can activate the lmo2 promoter through this element. Our studies elucidate the transcriptional regulation of this key transcription factor, and provide a transgenic system for the functional analysis of blood and blood vessels in zebrafish.
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Affiliation(s)
- Hao Zhu
- Division of Hematology/Oncology, Children's Hospital of Boston, Department of Pediatrics, Boston, MA 02115, USA
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17
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Bockamp E, Antunes C, Maringer M, Heck R, Presser K, Beilke S, Ohngemach S, Alt R, Cross M, Sprengel R, Hartwig U, Kaina B, Schmitt S, Eshkind L. Tetracycline-controlled transgenic targeting from the SCL locus directs conditional expression to erythrocytes, megakaryocytes, granulocytes, and c-kit-expressing lineage-negative hematopoietic cells. Blood 2006; 108:1533-41. [PMID: 16675709 DOI: 10.1182/blood-2005-12-012104] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The stem cell leukemia gene SCL, also known as TAL-1, encodes a basic helix-loop-helix transcription factor expressed in erythroid, myeloid, megakaryocytic, and hematopoietic stem cells. To be able to make use of the unique tissue-restricted and spatio-temporal expression pattern of the SCL gene, we have generated a knock-in mouse line containing the tTA-2S tetracycline transactivator under the control of SCL regulatory elements. Analysis of this mouse using different tetracycline-dependent reporter strains demonstrated that switchable transgene expression was restricted to erythrocytes, megakaryocytes, granulocytes, and, importantly, to the c-kit-expressing and lineage-negative cell fraction of the bone marrow. In addition, conditional transgene activation also was detected in a very minor population of endothelial cells and in the kidney. However, no activation of the reporter transgene was found in the brain of adult mice. These findings suggested that the expression of tetracycline-responsive reporter genes recapitulated the known endogenous expression pattern of SCL. Our data therefore demonstrate that exogenously inducible and reversible expression of selected transgenes in myeloid, megakaryocytic, erythroid, and c-kit-expressing lineage-negative bone marrow cells can be directed through SCL regulatory elements. The SCL knock-in mouse presented here represents a powerful tool for studying normal and malignant hematopoiesis in vivo.
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Affiliation(s)
- Ernesto Bockamp
- Institute of Toxicology/Mouse Genetics, Johannes Gutenberg-Universität Mainz, Obere Zahlbacher Str 67, 55131 Mainz, Germany.
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18
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Le Clech M, Chalhoub E, Dohet C, Roure V, Fichelson S, Moreau-Gachelin F, Mathieu D. PU.1/Spi-1 Binds to the Human TAL-1 Silencer to Mediate its Activity. J Mol Biol 2006; 355:9-19. [PMID: 16298389 DOI: 10.1016/j.jmb.2005.10.055] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2005] [Revised: 10/13/2005] [Accepted: 10/17/2005] [Indexed: 11/16/2022]
Abstract
The TAL-1/SCL gene encodes a basic helix-loop-helix (bHLH) transcription factor essential for primitive hematopoiesis and for adult erythroid and megakaryocytic development. Activated transcription of TAL-1 as a consequence of chromosomal rearrangements is associated with a high proportion of human T cell acute leukemias, showing that appropriate control of TAL-1 is crucial for the formation and subsequent fate of hematopoietic cells. Hence, the knowledge of the mechanisms, which govern the pattern of TAL-1 expression in hematopoiesis, is of great interest. We previously described a silencer in the 3'-untranslated region of human TAL-1, the activity of which is mediated through binding of a tissue-specific 40 kDa nuclear protein to a new DNA recognition motif, named tal-RE. Here, we show that tal-RE-binding activity, high in immature human hematopoietic progenitors is down regulated upon erythroid and megakaryocytic differentiation. This expression profile helped us to identify that PU.1/Spi-1 binds to the tal-RE sequences in vitro and occupies the TAL-1 silencer in vivo. By expressing a mutant protein containing only the ETS domain of PU.1 in human erythroleukemic HEL cells, we demonstrated that PU.1 mediates the transcriptional repression activity of the silencer. We found that ectopic PU.1 is not able to induce silencing activity in PU.1-negative Jurkat T cells, indicating that PU.1 activity, although necessary, is not sufficient to confer transcriptional repression activity to the TAL-1 silencer. Finally, we showed that the silencer is also active in TAL-1-negative myeloid HL60 cells that express PU.1 at high levels. In summary, our study shows that PU.1, in addition to its positive role in TAL-1 expression in early hematopoietic progenitors, may also act as a mediator of TAL-1 silencing in some hematopoietic lineages.
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Affiliation(s)
- Mikaël Le Clech
- Institut de Génétique Moléculaire-UMR5535-IFR22, CNRS 1919 Route de Mende F-34980 Montpellier, France
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19
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Göttgens B, Broccardo C, Sanchez MJ, Deveaux S, Murphy G, Göthert JR, Kotsopoulou E, Kinston S, Delaney L, Piltz S, Barton LM, Knezevic K, Erber WN, Begley CG, Frampton J, Green AR. The scl +18/19 stem cell enhancer is not required for hematopoiesis: identification of a 5' bifunctional hematopoietic-endothelial enhancer bound by Fli-1 and Elf-1. Mol Cell Biol 2004; 24:1870-83. [PMID: 14966269 PMCID: PMC350551 DOI: 10.1128/mcb.24.5.1870-1883.2004] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Analysis of cis-regulatory elements is central to understanding the genomic program for development. The scl/tal-1 transcription factor is essential for lineage commitment to blood cell formation and previous studies identified an scl enhancer (the +18/19 element) which was sufficient to target the vast majority of hematopoietic stem cells, together with hematopoietic progenitors and endothelium. Moreover, expression of scl under control of the +18/19 enhancer rescued blood progenitor formation in scl(-/-) embryos. However, here we demonstrate by using a knockout approach that, within the endogenous scl locus, the +18/19 enhancer is not necessary for the initiation of scl transcription or for the formation of hematopoietic cells. These results led to the identification of a bifunctional 5' enhancer (-3.8 element), which targets expression to hematopoietic progenitors and endothelium, contains conserved critical Ets sites, and is bound by Ets family transcription factors, including Fli-1 and Elf-1. These data demonstrate that two geographically distinct but functionally related enhancers regulate scl transcription in hematopoietic progenitors and endothelial cells and suggest that enhancers with dual hematopoietic-endothelial activity may represent a general strategy for regulating blood and endothelial development.
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Affiliation(s)
- Berthold Göttgens
- Department of Hematology, Cambridge Institute for Medical Research, University of Cambridge, United Kingdom.
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20
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Brudno M, Chapman M, Göttgens B, Batzoglou S, Morgenstern B. Fast and sensitive multiple alignment of large genomic sequences. BMC Bioinformatics 2003; 4:66. [PMID: 14693042 PMCID: PMC521198 DOI: 10.1186/1471-2105-4-66] [Citation(s) in RCA: 120] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2003] [Accepted: 12/23/2003] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Genomic sequence alignment is a powerful method for genome analysis and annotation, as alignments are routinely used to identify functional sites such as genes or regulatory elements. With a growing number of partially or completely sequenced genomes, multiple alignment is playing an increasingly important role in these studies. In recent years, various tools for pair-wise and multiple genomic alignment have been proposed. Some of them are extremely fast, but often efficiency is achieved at the expense of sensitivity. One way of combining speed and sensitivity is to use an anchored-alignment approach. In a first step, a fast search program identifies a chain of strong local sequence similarities. In a second step, regions between these anchor points are aligned using a slower but more accurate method. RESULTS Herein, we present CHAOS, a novel algorithm for rapid identification of chains of local pair-wise sequence similarities. Local alignments calculated by CHAOS are used as anchor points to improve the running time of DIALIGN, a slow but sensitive multiple-alignment tool. We show that this way, the running time of DIALIGN can be reduced by more than 95% for BAC-sized and longer sequences, without affecting the quality of the resulting alignments. We apply our approach to a set of five genomic sequences around the stem-cell-leukemia (SCL) gene and demonstrate that exons and small regulatory elements can be identified by our multiple-alignment procedure. CONCLUSION We conclude that the novel CHAOS local alignment tool is an effective way to significantly speed up global alignment tools such as DIALIGN without reducing the alignment quality. We likewise demonstrate that the DIALIGN/CHAOS combination is able to accurately align short regulatory sequences in distant orthologues.
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Affiliation(s)
- Michael Brudno
- Department of Computer Science, Stanford University, Stanford, CA 94305, USA
| | - Michael Chapman
- Department of Haematology, University of Cambridge, Cambridge Institute for Medical Research, Hills Road, Cambridge CB2 2XY, United Kingdom
| | - Berthold Göttgens
- Department of Haematology, University of Cambridge, Cambridge Institute for Medical Research, Hills Road, Cambridge CB2 2XY, United Kingdom
| | - Serafim Batzoglou
- Department of Computer Science, Stanford University, Stanford, CA 94305, USA
| | - Burkhard Morgenstern
- International Graduate School in Bioinformatics and Genome Research, Universität Bielefeld, Postfach 100131, 33501 Bielefeld, Germany
- University of Göttingen, Institute of Microbiology and Genetics, Goldschmidtstr. 1, 37077 Göttingen, Germany
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21
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Steunou V, Le Bousse-Kerdilès MC, Colin-Micouin A, Clay D, Chevillard S, Martyré MC. Altered transcription of the stem cell leukemia gene in myelofibrosis with myeloid metaplasia. Leukemia 2003; 17:1998-2006. [PMID: 14513050 DOI: 10.1038/sj.leu.2403089] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
An increased number of circulating CD34+ hematopoietic progenitors with a prominent proliferation of the megakaryocytic (MK) population are the hallmarks of the myeloproliferation in myelofibrosis with myeloid metaplasia (MMM). Analyzing the potential contribution of the stem cell leukemia (SCL) gene in MMM myeloproliferation was doubly interesting for SCL is expressed both in primitive-uncommitted progenitor cells and erythroid/MK cells, its transcription differentially initiating from promoter 1b and 1a, respectively. Our results show that: (i) the expression of SCL transcript is increased in peripheral blood mononuclear cells (PBMCs) from patients; (ii) SCL gene transcription is altered in MMM CD34+ progenitor cells sorted into CD34+CD41+ and CD34+CD41- subpopulations. Actually, in patients, SCL transcription initiated at promoter 1b is restricted to primitive CD34+CD41- progenitor cells, while it is detectable in both cell subsets from healthy subjects; (iii) the full-length isoform of SCL protein is present in patients' CD34+ cells and in PBMC; in the latter the SCL-expressing cells mainly belong to the MK lineage in which its sublocalization is both nuclear and cytoplasmic, which contrasts with the sole nuclear staining observed in normal MK cells. Our demonstration of altered expression and transcription of SCL in patients' hematopoietic cells emphasizes the possible contribution of this regulatory nuclear factor to the hematopoietic dysregulation, which is a feature of myelofibrosis with myeloid metaplasia.
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Affiliation(s)
- V Steunou
- INSERM U365, Institut Curie, Paris Cedex, France
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22
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Chapman MA, Charchar FJ, Kinston S, Bird CP, Grafham D, Rogers J, Grützner F, Graves JAM, Green AR, Göttgens B. Comparative and functional analyses of LYL1 loci establish marsupial sequences as a model for phylogenetic footprinting. Genomics 2003; 81:249-59. [PMID: 12659809 DOI: 10.1016/s0888-7543(03)00005-3] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Comparative genomic sequence analysis is a powerful technique for identifying regulatory regions in genomic DNA. However, its utility largely depends on the evolutionary distances between the species involved. Here we describe the screening of a genomic BAC library from the stripe-faced dunnart, Sminthopsis macroura, formerly known as the narrow-footed marsupial mouse. We isolated a clone containing the LYL1 locus, completely sequenced the 60.6-kb insert, and compared it with orthologous human and mouse sequences. Noncoding homology was substantially reduced in the human/dunnart analysis compared with human/mouse, yet we could readily identify all promoters and exons. Human/mouse/dunnart alignments of the LYL1 candidate promoter allowed us to identify putative transcription factor binding sites, revealing a pattern highly reminiscent of critical regulatory regions of the LYL1 paralogue, SCL. This newly identified LYL1 promoter showed strong activity in myeloid progenitor cells and was bound in vivo by Fli1, Elf1, and Gata2-transcription factors all previously shown to bind to the SCL stem cell enhancer. This study represents the first large-scale comparative analysis involving marsupial genomic sequence and demonstrates that such comparisons provide a powerful approach to characterizing mammalian regulatory elements.
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Affiliation(s)
- Michael A Chapman
- Department of Haematology, Cambridge Institute for Medical Research, Cambridge University, Hills Road, Cambridge CB2 2XY, UK
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23
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Göttgens B, Nastos A, Kinston S, Piltz S, Delabesse EC, Stanley M, Sanchez MJ, Ciau-Uitz A, Patient R, Green AR. Establishing the transcriptional programme for blood: the SCL stem cell enhancer is regulated by a multiprotein complex containing Ets and GATA factors. EMBO J 2002; 21:3039-50. [PMID: 12065417 PMCID: PMC126046 DOI: 10.1093/emboj/cdf286] [Citation(s) in RCA: 182] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2002] [Revised: 04/18/2002] [Accepted: 04/18/2002] [Indexed: 12/22/2022] Open
Abstract
Stem cells are a central feature of metazoan biology. Haematopoietic stem cells (HSCs) represent the best-characterized example of this phenomenon, but the molecular mechanisms responsible for their formation remain obscure. The stem cell leukaemia (SCL) gene encodes a basic helix-loop-helix (bHLH) transcription factor with an essential role in specifying HSCs. Here we have addressed the transcriptional hierarchy responsible for HSC formation by characterizing an SCL 3' enhancer that targets expression to HSCs and endothelium and their bipotential precursors, the haemangioblast. We have identified three critical motifs, which are essential for enhancer function and bind GATA-2, Fli-1 and Elf-1 in vivo. Our results suggest that these transcription factors are key components of an enhanceosome responsible for activating SCL transcription and establishing the transcriptional programme required for HSC formation.
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Affiliation(s)
- Berthold Göttgens
- University of Cambridge Department of Haematology, Cambridge Institute for Medical Research, Hills Road, Cambridge CB2 2XY and
Institute of Genetics, Nottingham University, Queen’s Medical Centre, Nottingham NG7 2UH, UK Corresponding author e-mail:
| | - Aristotelis Nastos
- University of Cambridge Department of Haematology, Cambridge Institute for Medical Research, Hills Road, Cambridge CB2 2XY and
Institute of Genetics, Nottingham University, Queen’s Medical Centre, Nottingham NG7 2UH, UK Corresponding author e-mail:
| | | | | | | | | | | | - Aldo Ciau-Uitz
- University of Cambridge Department of Haematology, Cambridge Institute for Medical Research, Hills Road, Cambridge CB2 2XY and
Institute of Genetics, Nottingham University, Queen’s Medical Centre, Nottingham NG7 2UH, UK Corresponding author e-mail:
| | - Roger Patient
- University of Cambridge Department of Haematology, Cambridge Institute for Medical Research, Hills Road, Cambridge CB2 2XY and
Institute of Genetics, Nottingham University, Queen’s Medical Centre, Nottingham NG7 2UH, UK Corresponding author e-mail:
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24
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Sinclair AM, Bench AJ, Bloor AJC, Li J, Göttgens B, Stanley ML, Miller J, Piltz S, Hunter S, Nacheva EP, Sanchez MJ, Green AR. Rescue of the lethal scl(-/-) phenotype by the human SCL locus. Blood 2002; 99:3931-8. [PMID: 12010791 DOI: 10.1182/blood.v99.11.3931] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
The stem cell leukemia (SCL) gene encodes a basic helix-loop-helix transcription factor with a critical role in the development of both blood and endothelium. Loss-of-function studies have shown that SCL is essential for the formation of hematopoietic stem cells, for subsequent erythroid development and for yolk sac angiogenesis. SCL exhibits a highly conserved pattern of expression from mammals to teleost fish. Several murine SCL enhancers have been identified, each of which directs reporter gene expression in vivo to a subdomain of the normal SCL expression pattern. However, regulatory elements necessary for SCL expression in erythroid cells remain to be identified and the size of the chromosomal domain needed to support appropriate SCL transcription is unknown. Here we demonstrate that a 130-kilobase (kb) yeast artificial chromosome (YAC) containing the human SCL locus completely rescued the embryonic lethal phenotype of scl(-/-) mice. Rescued YAC(+) scl(-/-) mice were born in appropriate Mendelian ratios, were healthy and fertile, and exhibited no detectable abnormality of yolk sac, fetal liver, or adult hematopoiesis. The human SCL protein can therefore substitute for its murine homologue. In addition, our results demonstrate that the human SCL YAC contains the chromosomal domain necessary to direct expression to the erythroid lineage and to all other tissues in which SCL performs a nonredundant essential function.
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Affiliation(s)
- Angus M Sinclair
- University of Cambridge, Department of Haematology, Cambridge Institute for Medical Research, Hills Road, Cambridge, CB2 2XY, United Kingdom
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25
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Göttgens B, Barton LM, Chapman MA, Sinclair AM, Knudsen B, Grafham D, Gilbert JGR, Rogers J, Bentley DR, Green AR. Transcriptional regulation of the stem cell leukemia gene (SCL)--comparative analysis of five vertebrate SCL loci. Genome Res 2002; 12:749-59. [PMID: 11997341 PMCID: PMC186570 DOI: 10.1101/gr.45502] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2001] [Accepted: 03/19/2002] [Indexed: 12/25/2022]
Abstract
The stem cell leukemia (SCL) gene encodes a bHLH transcription factor with a pivotal role in hematopoiesis and vasculogenesis and a pattern of expression that is highly conserved between mammals and zebrafish. Here we report the isolation and characterization of the zebrafish SCL locus together with the identification of three neighboring genes, IER5, MAP17, and MUPP1. This region spans 68 kb and comprises the longest zebrafish genomic sequence currently available for comparison with mammalian, chicken, and pufferfish sequences. Our data show conserved synteny between zebrafish and mammalian SCL and MAP17 loci, thus suggesting the likely genomic domain necessary for the conserved pattern of SCL expression. Long-range comparative sequence analysis/phylogenetic footprinting was used to identify noncoding conserved sequences representing candidate transcriptional regulatory elements. The SCL promoter/enhancer, exon 1, and the poly(A) region were highly conserved, but no homology to other known mouse SCL enhancers was detected in the zebrafish sequence. A combined homology/structure analysis of the poly(A) region predicted consistent structural features, suggesting a conserved functional role in mRNA regulation. Analysis of the SCL promoter/enhancer revealed five motifs, which were conserved from zebrafish to mammals, and each of which is essential for the appropriate pattern or level of SCL transcription.
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Affiliation(s)
- Berthold Göttgens
- Cambridge Institute for Medical Research, Cambridge University, Cambridge, CB2 2XY, United Kingdom.
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26
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Bloor AJC, Sánchez MJ, Green AR, Göttgens B. The role of the stem cell leukemia (SCL) gene in hematopoietic and endothelial lineage specification. JOURNAL OF HEMATOTHERAPY & STEM CELL RESEARCH 2002; 11:195-206. [PMID: 11983093 DOI: 10.1089/152581602753658402] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Anatomical observations made at the beginning of the twentieth century revealed an intimate association between the ontogeny of blood and endothelium and led to the hypothesis of a common cell of origin termed the hemangioblast. However, the precise nature of the cellular intermediates involved in the development of both lineages from uncommitted precursors to mature cell types is still the subject of ongoing studies, as are the molecular mechanisms driving this process. There is clear evidence that lineage-restricted transcription factors play a central role in the genesis of mature lineage committed cells from multipotent progenitors. Amongst these, the basic helix-loop-helix (bHLH) family is of key importance for cell fate determination in the development of the hematopoietic system and beyond. This article will review the current evidence for the common origin of blood and endothelium, focusing on the function of the bHLH protein encoded by the stem cell leukemia (SCL) gene, and its role as a pivotal regulator of hematopoiesis and vasculogenesis.
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Affiliation(s)
- Adrian J C Bloor
- Cambridge University Department of Haematology, Cambridge Institute for Medical Research, Hills Road, Cambridge, CB2 2XY, UK
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27
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Sánchez MJ, Bockamp EO, Miller J, Gambardella L, Green AR. Selective rescue of early haematopoietic progenitors in Scl–/– mice by expressing Scl under the control of a stem cell enhancer. Development 2001; 128:4815-27. [PMID: 11731461 DOI: 10.1242/dev.128.23.4815] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The stem cell leukaemia gene (Scl) encodes a basic helix-loop-helix transcription factor with a pivotal role in both haematopoiesis and endothelial development. During mouse development, Scl is first expressed in extra-embryonic mesoderm, and is required for the generation of all haematopoietic lineages and normal yolk sac angiogenesis. Ectopic expression of Scl during zebrafish development specifies haemangioblast formation from early mesoderm. These results suggest that SCL is essential for establishing the transcriptional programme responsible for the formation of haematopoietic stem cells and have focused attention on the transcriptional regulation of Scl itself. Previous studies have identified a panel of Scl enhancers each of which directed expression to a subdomain of the normal Scl expression pattern. Among them, a 3′ enhancer directed expression during development to vascular endothelium and haematopoietic progenitors but not to Ter119+ erythroid cells. The expression in haematopoietic stem cells, however, remained undetermined. We demonstrate that this 3′ enhancer directs lacZ expression in transgenic mice to most foetal and adult long-term repopulating haematopoietic stem cells, and therefore functions as a stem cell enhancer. Consistent with these results, expression in Scl–/– embryos of exogenous Scl driven by the stem cell enhancer rescued the formation of early haematopoietic progenitors and also resulted in normal yolk sac angiogenesis. By contrast, erythropoiesis remained markedly deficient in rescued embryos. This observation is consistent with the inactivity of the stem cell enhancer in erythroid cells and reveals an essential role for SCL during erythroid differentiation in vivo.
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Affiliation(s)
- M J Sánchez
- University of Cambridge, Department of Haematology, CIMR Centre, Hills Road, Cambridge CB2 2XY, UK.
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Barton LM, Gottgens B, Gering M, Gilbert JG, Grafham D, Rogers J, Bentley D, Patient R, Green AR. Regulation of the stem cell leukemia (SCL) gene: a tale of two fishes. Proc Natl Acad Sci U S A 2001; 98:6747-52. [PMID: 11381108 PMCID: PMC34424 DOI: 10.1073/pnas.101532998] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2000] [Indexed: 11/18/2022] Open
Abstract
The stem cell leukemia (SCL) gene encodes a tissue-specific basic helix-loop-helix (bHLH) protein with a pivotal role in hemopoiesis and vasculogenesis. Several enhancers have been identified within the murine SCL locus that direct reporter gene expression to subdomains of the normal SCL expression pattern, and long-range sequence comparisons of the human and murine SCL loci have identified additional candidate enhancers. To facilitate the characterization of regulatory elements, we have sequenced and analyzed 33 kb of the SCL genomic locus from the pufferfish Fugu rubripes, a species with a highly compact genome. Although the pattern of SCL expression is highly conserved from mammals to teleost fish, the genes flanking pufferfish SCL were unrelated to those known to flank both avian and mammalian SCL genes. These data suggest that SCL regulatory elements are confined to the region between the upstream and downstream flanking genes, a region of 65 kb in human and 8.5 kb in pufferfish. Consistent with this hypothesis, the entire 33-kb pufferfish SCL locus directed appropriate expression to hemopoietic and neural tissue in transgenic zebrafish embryos, as did a 10.4-kb fragment containing the SCL gene and extending to the 5' and 3' flanking genes. These results demonstrate the power of combining the compact genome of the pufferfish with the advantages that zebrafish provide for studies of gene regulation during development. Furthermore, the pufferfish SCL locus provides a powerful tool for the manipulation of hemopoiesis and vasculogenesis in vivo.
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Affiliation(s)
- L M Barton
- Department of Hematology, Cambridge Institute for Medical Research, University of Cambridge, Addenbrookes Hospital, Cambridge CB2 2XY, United Kingdom
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29
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Rothenberg EV. Mapping of complex regulatory elements by pufferfish/zebrafish transgenesis. Proc Natl Acad Sci U S A 2001; 98:6540-2. [PMID: 11390989 PMCID: PMC34387 DOI: 10.1073/pnas.131199098] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- E V Rothenberg
- Division of Biology, 156-29, California Institute of Technology, Pasadena, CA 91125, USA.
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Göttgens B, Gilbert JG, Barton LM, Grafham D, Rogers J, Bentley DR, Green AR. Long-range comparison of human and mouse SCL loci: localized regions of sensitivity to restriction endonucleases correspond precisely with peaks of conserved noncoding sequences. Genome Res 2001; 11:87-97. [PMID: 11156618 PMCID: PMC311011 DOI: 10.1101/gr.153001] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2000] [Accepted: 10/12/2000] [Indexed: 11/24/2022]
Abstract
Long-range comparative sequence analysis provides a powerful strategy for identifying conserved regulatory elements. The stem cell leukemia (SCL) gene encodes a bHLH transcription factor with a pivotal role in hemopoiesis and vasculogenesis, and it displays a highly conserved expression pattern. We present here a detailed sequence comparison of 193 kb of the human SCL locus to 234 kb of the mouse SCL locus. Four new genes have been identified together with an ancient mitochondrial insertion in the human locus. The SCL gene is flanked upstream by the SIL gene and downstream by the MAP17 gene in both species, but the gene order is not collinear downstream from MAP17. To facilitate rapid identification of candidate regulatory elements, we have developed a new sequence analysis tool (SynPlot) that automates the graphical display of large-scale sequence alignments. Unlike existing programs, SynPlot can display the locus features of more than one sequence, thereby indicating the position of homology peaks relative to the structure of all sequences in the alignment. In addition, high-resolution analysis of the chromatin structure of the mouse SCL gene permitted the accurate positioning of localized zones accessible to restriction endonucleases. Zones known to be associated with functional regulatory regions were found to correspond precisely with peaks of human/mouse homology, thus demonstrating that long-range human/mouse sequence comparisons allow accurate prediction of the extent of accessible DNA associated with active regulatory regions.
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Affiliation(s)
- B Göttgens
- The Wellcome Trust Centre for Molecular Mechanisms in Disease, Cambridge Institute for Medical Research, Addenbrooke's Hospital Site, Cambridge CB2 2XY, UK.
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31
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Ziegler B, Testa U, Condorelli G, Vitelli L, Valtieri M, Peschle C. Unilineage hematopoietic differentiation in bulk and single cell culture. Stem Cells 2000; 16 Suppl 1:51-73. [PMID: 11012148 DOI: 10.1002/stem.5530160808] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The rarity of hematopoietic stem and progenitor cells (HSCs, HPCs) has hampered the analysis of cellular and molecular mechanisms underlying early hematopoiesis. Methodology for HPC purification has partially offset this limitation. A further hurdle has been represented by the heterogeneity of the analyzed HPC/precursor populations: recently, development of unilineage HPC differentiation cultures has provided homogeneous populations of hematopoietic cells, particularly in the early differentiation state, i.e., populations pertaining to a single lineage and a restricted stage of differentiation/maturation, but sufficiently large for cellular/molecular analysis. This report focuses on the development and characterization of the unilineage HPC differentiation culture systems. A section is devoted to selected cellular and molecular mechanisms underlying hematopoiesis, which have been investigated by the HPC unilineage culture approach. Finally, recent advances in the development of HPC unilineage cultures at single cell level are discussed.
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Affiliation(s)
- B Ziegler
- Department of Medicine, Eberhard-Karls University Tübingen, Germany
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Abstract
We have identified a novel regulatory erythroid kinase (REDK) that is homologous to a family of dual-specificity kinases. The yeast homolog of REDK negatively regulates cell division, suggesting a similar function for REDK, which is primarily localized in the nucleus. REDK is present in hematopoietic tissues, such as bone marrow and fetal liver, but the RNA is expressed at significant levels only in erythroid or erythropoietin (EPO)-responsive cells. Two novel forms of cDNA (long and short) for REDK have been isolated that appear to be alternative splice products and imply the presence of polypeptides with differing amino termini. The ratio of short-to-long forms of REDK increases dramatically in CD34+ cells cultured with EPO, suggesting differing regulation and function for each form. REDK is predominantly found in nuclear, rather than cytoplasmic, protein extracts, and immunoprecipitated REDK is active in phosphorylating histones H2b, H3, myelin basic protein, and other coimmunoprecipitated proteins. Antisense REDK oligonucleotides promote erythroid colony formation by human bone marrow cells, without affecting colony-forming unit (CFU)-GM, CFU-G, or CFU-GEMM numbers. Maximal numbers of CFU-E and burst-forming unit–erythroid were increased, and CFU-E displayed increased sensitivity to suboptimal EPO concentrations. The data indicate that REDK acts as a brake to retard erythropoiesis.
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Göttgens B, Barton LM, Gilbert JG, Bench AJ, Sanchez MJ, Bahn S, Mistry S, Grafham D, McMurray A, Vaudin M, Amaya E, Bentley DR, Green AR, Sinclair AM. Analysis of vertebrate SCL loci identifies conserved enhancers. Nat Biotechnol 2000; 18:181-6. [PMID: 10657125 DOI: 10.1038/72635] [Citation(s) in RCA: 140] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The SCL gene encodes a highly conserved bHLH transcription factor with a pivotal role in hemopoiesis and vasculogenesis. We have sequenced and analyzed 320 kb of genomic DNA composing the SCL loci from human, mouse, and chicken. Long-range sequence comparisons demonstrated multiple peaks of human/mouse homology, a subset of which corresponded precisely with known SCL enhancers. Comparisons between mammalian and chicken sequences identified some, but not all, SCL enhancers. Moreover, one peak of human/mouse homology (+23 region), which did not correspond to a known enhancer, showed significant homology to an analogous region of the chicken SCL locus. A transgenic Xenopus reporter assay was established and demonstrated that the +23 region contained a new neural enhancer. This combination of long-range comparative sequence analysis with a high-throughput transgenic bioassay provides a powerful strategy for identifying and characterizing developmentally important enhancers.
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Affiliation(s)
- B Göttgens
- University of Cambridge, Department of Haematology, MRC Centre, Hills Road, Cambridge CB2 2QH, UK
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Courtes C, Lecointe N, Le Cam L, Baudoin F, Sardet C, Mathieu-Mahul D. Erythroid-specific inhibition of the tal-1 intragenic promoter is due to binding of a repressor to a novel silencer. J Biol Chem 2000; 275:949-58. [PMID: 10625632 DOI: 10.1074/jbc.275.2.949] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The basic helix-loop-helix tal-1 gene plays a key role in hematopoiesis, and its expression is tightly controlled through alternative promoters and complex interactions of cis-acting regulatory elements. tal-1 is not expressed in normal T cells, but its transcription is constitutive in a large proportion of human T cell leukemias. We have previously described a downstream initiation of tal-1 transcription specifically associated with a subset of T cell leukemias that leads to the production of NH(2)-truncated TAL-1 proteins. In this study, we characterize the human promoter (promoter IV), embedded within a GC-rich region in exon IV, responsible for this transcriptional activity. The restriction of promoter IV usage is assured by a novel silencer element in the 3'-untranslated region of the human gene that represses its activity in erythroid but not in T cells. The silencer activity is mediated through binding of a tissue-specific nuclear factor to a novel protein recognition motif (designated tal-RE) in the silencer. Mutation of a single residue within the tal-RE abolishes both specific protein binding and silencing activity. Altogether, our results demonstrate that the tal-1 promoter IV is actively repressed in cells of the erythro-megakaryocytic lineage and that this repression is released in leukemic T cells, resulting in the expression of the tal-1 truncated transcript.
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Affiliation(s)
- C Courtes
- Institut de Génétique Moléculaire, UMR 5535, IFR 24, 1919 Route de Mende, F 34293, Montpellier, France
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Affiliation(s)
- P J Ho
- Institute of Hematology, Royal Prince Alfred Hospital, Australia.
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Barton LM, Göttgens B, Green AR. The stem cell leukaemia (SCL) gene: a critical regulator of haemopoietic and vascular development. Int J Biochem Cell Biol 1999; 31:1193-207. [PMID: 10582347 DOI: 10.1016/s1357-2725(99)00082-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- L M Barton
- Department of Haematology, University of Cambridge, MRC Centre, UK
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Sánchez M, Göttgens B, Sinclair AM, Stanley M, Begley CG, Hunter S, Green AR. An SCL 3′ enhancer targets developing endothelium together with embryonic and adult haematopoietic progenitors. Development 1999; 126:3891-904. [PMID: 10433917 DOI: 10.1242/dev.126.17.3891] [Citation(s) in RCA: 106] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The SCL gene encodes a basic helix-loop-helix transcription factor which is expressed in early haematopoietic progenitors throughout ontogeny and is essential for the normal development of blood and blood vessels. Transgenic studies have characterised spatially distinct 5′ enhancers which direct lacZ expression to subdomains of the normal SCL expression pattern, but the same elements failed to produce appropriate haematopoietic expression. We now describe an SCL 3′ enhancer with unique properties. It directed lacZ expression in transgenic mice to extra-embryonic mesoderm and subsequently to both endothelial cells and to a subset of blood cells at multiple sites of embryonic haematopoiesis including the yolk sac, para-aortic splanchnopleura and AGM region. The 3′ enhancer also targeted expression to haematopoietic progenitors in both foetal liver and adult bone marrow. Purified lacZ(+)cells were highly enriched for clonogenic myeloid and erythroid progenitors as well as day-12 spleen colony forming units (CFU-S). Within the total gated population from bone marrow, 95% of the myeloid and 90% of the erythroid colony-forming cells were contained in the lacZ(+) fraction, as were 98% of the CFU-S. Activation of the enhancer did not require SCL protein. On the contrary, transgene expression in yolk sacs was markedly increased in an SCL−/− background, suggesting that SCL is subject to negative autoregulation. Alternatively the SCL−/− environment may alter differentiation of extra-embryonic mesoderm and result in an increased number of cells capable of expressing high levels of the transgene. Our data represents the first description of an enhancer that integrates information necessary for expression in developing endothelium and early haematopoietic progenitors at distinct times and sites throughout ontogeny. This enhancer provides a potent tool for the manipulation of haematopoiesis and vasculogenesis in vivo.
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Affiliation(s)
- M Sánchez
- University of Cambridge, Department of Haematology, MRC Centre, Hills Road, Cambridge CB2 2QH, UK
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Sinclair AM, Göttgens B, Barton LM, Stanley ML, Pardanaud L, Klaine M, Gering M, Bahn S, Sanchez M, Bench AJ, Fordham JL, Bockamp E, Green AR. Distinct 5' SCL enhancers direct transcription to developing brain, spinal cord, and endothelium: neural expression is mediated by GATA factor binding sites. Dev Biol 1999; 209:128-42. [PMID: 10208748 DOI: 10.1006/dbio.1999.9236] [Citation(s) in RCA: 91] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The SCL gene encodes a basic helix-loop-helix transcription factor with a pivotal role in the development of endothelium and of all hematopoietic lineages. SCL is also expressed in the central nervous system, although its expression pattern has not been examined in detail and its function in neural development is unknown. In this article we present the first analysis of SCL transcriptional regulation in vivo. We have identified three spatially distinct regulatory modules, each of which was both necessary and sufficient to direct reporter gene expression in vivo to three different regions within the normal SCL expression domain, namely, developing endothelium, midbrain, and hindbrain/spinal cord. In addition we have demonstrated that GATA factor binding sites are essential for neural expression of the SCL constructs. The midbrain element was particularly powerful and axonal lacZ expression revealed the details of axonal projections, thus implicating SCL in the development of occulomotor, pupillary, or retinotectal pathways. The neural expression pattern of the SCL gene was highly conserved in mouse, chicken, and zebrafish embryos and the 5' region of the chicken SCL locus exhibited a striking degree of functional conservation in transgenic mice. These data suggest that SCL performs critical functions in neural development. The regulatory elements identified here provide important tools for analyzing these functions.
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Affiliation(s)
- A M Sinclair
- Department of Haematology, University of Cambridge, MRC Centre, Hills Road, Cambridge, CB2 2QH, United Kingdom
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41
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Bockamp EO, Fordham JL, Göttgens B, Murrell AM, Sanchez MJ, Green AR. Transcriptional regulation of the stem cell leukemia gene by PU.1 and Elf-1. J Biol Chem 1998; 273:29032-42. [PMID: 9786909 DOI: 10.1074/jbc.273.44.29032] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The SCL gene, also known as tal-1, encodes a basic helix-loop-helix transcription factor that is pivotal for the normal development of all hematopoietic lineages. SCL is expressed in committed erythroid, mast, and megakaryocytic cells as well as in hematopoietic stem cells. Nothing is known about the regulation of SCL transcription in mast cells, and in other lineages GATA-1 is the only tissue-specific transcription factor recognized to regulate the SCL gene. We have therefore analyzed the molecular mechanisms underlying SCL expression in mast cells. In this paper, we demonstrate that SCL promoter 1a was regulated by GATA-1 together with Sp1 and Sp3 in a manner similar to the situation in erythroid cells. However, SCL promoter 1b was strongly active in mast cells, in marked contrast to the situation in erythroid cells. Full activity of promoter 1b was dependent on ETS and Sp1/3 motifs. Transcription factors PU.1, Elf-1, Sp1, and Sp3 were all present in mast cell extracts, bound to promoter 1b and transactivated promoter 1b reporter constructs. These data provide the first evidence that the SCL gene is a direct target for PU.1, Elf-1, and Sp3.
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Affiliation(s)
- E O Bockamp
- University of Cambridge, Department of Haematology, Medical Research Council Centre, Hills Road, Cambridge CB2 2QH, United Kingdom
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