1
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Li Y, Liao Z, Luo H, Benyoucef A, Kang Y, Lai Q, Dovat S, Miller B, Chepelev I, Li Y, Zhao K, Brand M, Huang S. Alteration of CTCF-associated chromatin neighborhood inhibits TAL1-driven oncogenic transcription program and leukemogenesis. Nucleic Acids Res 2020; 48:3119-3133. [PMID: 32086528 PMCID: PMC7102946 DOI: 10.1093/nar/gkaa098] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Revised: 02/03/2020] [Accepted: 02/06/2020] [Indexed: 12/23/2022] Open
Abstract
Aberrant activation of the TAL1 is associated with up to 60% of T-ALL cases and is involved in CTCF-mediated genome organization within the TAL1 locus, suggesting that CTCF boundary plays a pathogenic role in T-ALL. Here, we show that -31-Kb CTCF binding site (-31CBS) serves as chromatin boundary that defines topologically associating domain (TAD) and enhancer/promoter interaction required for TAL1 activation. Deleted or inverted -31CBS impairs TAL1 expression in a context-dependent manner. Deletion of -31CBS reduces chromatin accessibility and blocks long-range interaction between the +51 erythroid enhancer and TAL1 promoter-1 leading to inhibition of TAL1 expression in erythroid cells, but not T-ALL cells. However, in TAL1-expressing T-ALL cells, the leukemia-prone TAL1 promoter-IV specifically interacts with the +19 stem cell enhancer located 19 Kb downstream of TAL1 and this interaction is disrupted by the -31CBS inversion in T-ALL cells. Inversion of -31CBS in Jurkat cells alters chromatin accessibility, histone modifications and CTCF-mediated TAD leading to inhibition of TAL1 expression and TAL1-driven leukemogenesis. Thus, our data reveal that -31CBS acts as critical regulator to define +19-enhancer and the leukemic prone promoter IV interaction for TAL1 activation in T-ALL. Manipulation of CTCF boundary can alter TAL1 TAD and oncogenic transcription networks in leukemogenesis.
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Affiliation(s)
- Ying Li
- Department of Pediatrics and Pharmacology, Pennsylvania State University College of Medicine, Hershey, PA 17033, USA
| | - Ziwei Liao
- Department of Biochemistry & Molecular Biology, University of Florida College of Medicine, Gainesville, FL 32610, USA.,Institute of Hematology, Jinan University Medical College, ShiPai, Guangzhou, 510632, China
| | - Huacheng Luo
- Department of Pediatrics and Pharmacology, Pennsylvania State University College of Medicine, Hershey, PA 17033, USA
| | - Aissa Benyoucef
- The Sprott Center for Stem Cell Research, Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, Ontario K1H 8L6, Canada
| | - Yuanyuan Kang
- Department of Biochemistry & Molecular Biology, University of Florida College of Medicine, Gainesville, FL 32610, USA
| | - Qian Lai
- Department of Pediatrics and Pharmacology, Pennsylvania State University College of Medicine, Hershey, PA 17033, USA
| | - Sinisa Dovat
- Department of Pediatrics and Pharmacology, Pennsylvania State University College of Medicine, Hershey, PA 17033, USA
| | - Barbara Miller
- Department of Pediatrics and Pharmacology, Pennsylvania State University College of Medicine, Hershey, PA 17033, USA
| | - Iouri Chepelev
- Laboratory of Molecular Immunology, National Heart, Lung and Blood Institute, NIH, Bethesda, MD 20814, USA.,Center for Autoimmune Genomics and Etiology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Yangqiu Li
- Institute of Hematology, Jinan University Medical College, ShiPai, Guangzhou, 510632, China
| | - Keji Zhao
- Laboratory of Molecular Immunology, National Heart, Lung and Blood Institute, NIH, Bethesda, MD 20814, USA
| | - Marjorie Brand
- The Sprott Center for Stem Cell Research, Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, Ontario K1H 8L6, Canada
| | - Suming Huang
- Department of Pediatrics and Pharmacology, Pennsylvania State University College of Medicine, Hershey, PA 17033, USA.,Department of Biochemistry & Molecular Biology, University of Florida College of Medicine, Gainesville, FL 32610, USA
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2
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Cañete A, Comaills V, Prados I, Castro AM, Hammad S, Ybot-Gonzalez P, Bockamp E, Hengstler JG, Gottgens B, Sánchez MJ. Characterization of a Fetal Liver Cell Population Endowed with Long-Term Multiorgan Endothelial Reconstitution Potential. Stem Cells 2016; 35:507-521. [PMID: 27615355 PMCID: PMC5298023 DOI: 10.1002/stem.2494] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Revised: 07/27/2016] [Accepted: 08/10/2016] [Indexed: 12/26/2022]
Abstract
Stable reconstitution of vascular endothelial beds upon transplantation of progenitor cells represents an important challenge due to the paucity and generally limited integration/expansion potential of most identified vascular related cell subsets. We previously showed that mouse fetal liver (FL) hemato/vascular cells from day 12 of gestation (E12), expressing the Stem Cell Leukaemia (SCL) gene enhancer transgene (SCL‐PLAP+ cells), had robust endothelial engraftment potential when transferred to the blood stream of newborns or adult conditioned recipients, compared to the scarce vascular contribution of adult bone marrow cells. However, the specific SCL‐PLAP+ hematopoietic or endothelial cell subset responsible for the long‐term reconstituting endothelial cell (LTR‐EC) activity and its confinement to FL developmental stages remained unknown. Using a busulfan‐treated newborn transplantation model, we show that LTR‐EC activity is restricted to the SCL‐PLAP+VE‐cadherin+CD45− cell population, devoid of hematopoietic reconstitution activity and largely composed by Lyve1+ endothelial‐committed cells. SCL‐PLAP+ Ve‐cadherin+CD45− cells contributed to the liver sinusoidal endothelium and also to the heart, kidney and lung microvasculature. LTR‐EC activity was detected at different stages of FL development, yet marginal activity was identified in the adult liver, revealing unknown functional differences between fetal and adult liver endothelial/endothelial progenitors. Importantly, the observations that expanding donor‐derived vascular grafts colocalize with proliferating hepatocyte‐like cells and participate in the systemic circulation, support their functional integration into young livers. These findings offer new insights into the engraftment, phonotypical, and developmental characterization of a novel endothelial/endothelial progenitor cell subtype with multiorgan LTR‐EC activity, potentially instrumental for the treatment/genetic correction of vascular diseases. Stem Cells2017;35:507–521
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Affiliation(s)
- Ana Cañete
- Centro Andaluz de Biología del Desarrollo (CABD), Consejo Superior de Investigaciones Científicas (CSIC), Junta de Andalucía (JA), Universidad Pablo de Olavide (UPO), Sevilla, Spain
| | - Valentine Comaills
- Centro Andaluz de Biología del Desarrollo (CABD), Consejo Superior de Investigaciones Científicas (CSIC), Junta de Andalucía (JA), Universidad Pablo de Olavide (UPO), Sevilla, Spain
| | - Isabel Prados
- Centro Andaluz de Biología del Desarrollo (CABD), Consejo Superior de Investigaciones Científicas (CSIC), Junta de Andalucía (JA), Universidad Pablo de Olavide (UPO), Sevilla, Spain
| | - Ana María Castro
- Centro Andaluz de Biología del Desarrollo (CABD), Consejo Superior de Investigaciones Científicas (CSIC), Junta de Andalucía (JA), Universidad Pablo de Olavide (UPO), Sevilla, Spain
| | - Seddik Hammad
- Faculty of Veterinary Medicine, Department of Forensic Medicine and Veterinary Toxicology, South Valley University, Qena, Egypt.,Leibniz Research Center for Working Environment and Human Factors (IfADo), TU Dortmund University, Dortmund, Germany
| | - Patricia Ybot-Gonzalez
- Instituto de Biomedicina de Sevilla (IBIS), Hospital Universitario Virgen del Rocío, CSIC, Universidad de Sevilla, Seville, Spain
| | - Ernesto Bockamp
- Institute of Translational Immunology, University Medical Center, Johannes Gutenberg University, Mainz, Germany
| | - Jan G Hengstler
- Leibniz Research Center for Working Environment and Human Factors (IfADo), TU Dortmund University, Dortmund, Germany
| | - Bertie Gottgens
- Cambridge Institute for Medical Research & Wellcome Trust and MRC Cambridge Stem Cell Institute, Cambridge University, United Kingdom
| | - María José Sánchez
- Centro Andaluz de Biología del Desarrollo (CABD), Consejo Superior de Investigaciones Científicas (CSIC), Junta de Andalucía (JA), Universidad Pablo de Olavide (UPO), Sevilla, Spain
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3
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Patel B, Kang Y, Cui K, Litt M, Riberio MSJ, Deng C, Salz T, Casada S, Fu X, Qiu Y, Zhao K, Huang S. Aberrant TAL1 activation is mediated by an interchromosomal interaction in human T-cell acute lymphoblastic leukemia. Leukemia 2014; 28:349-61. [PMID: 23698277 PMCID: PMC10921969 DOI: 10.1038/leu.2013.158] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2013] [Revised: 05/09/2013] [Accepted: 05/16/2013] [Indexed: 01/21/2023]
Abstract
Long-range chromatin interactions control metazoan gene transcription. However, the involvement of intra- and interchromosomal interactions in development and oncogenesis remains unclear. TAL1/SCL is a critical transcription factor required for the development of all hematopoietic lineages; yet, aberrant TAL1 transcription often occurs in T-cell acute lymphoblastic leukemia (T-ALL). Here, we report that oncogenic TAL1 expression is regulated by different intra- and interchromosomal loops in normal hematopoietic and leukemic cells, respectively. These intra- and interchromosomal loops alter the cell-type-specific enhancers that interact with the TAL1 promoter. We show that human SET1 (hSET1)-mediated H3K4 methylations promote a long-range chromatin loop, which brings the +51 enhancer in close proximity to TAL1 promoter 1 in erythroid cells. The CCCTC-binding factor (CTCF) facilitates this long-range enhancer/promoter interaction of the TAL1 locus in erythroid cells while blocking the same enhancer/promoter interaction of the TAL1 locus in human T-cell leukemia. In human T-ALL, a T-cell-specific transcription factor c-Maf-mediated interchromosomal interaction brings the TAL1 promoter into close proximity with a T-cell-specific regulatory element located on chromosome 16, activating aberrant TAL1 oncogene expression. Thus, our study reveals a novel molecular mechanism involving changes in three-dimensional chromatin interactions that activate the TAL1 oncogene in human T-cell leukemia.
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Affiliation(s)
- B Patel
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, FL, USA
- These authors contributed equally to this work
| | - Y Kang
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, FL, USA
- College of Life Science, Jilin University, Changchun, China
- These authors contributed equally to this work
| | - K Cui
- Center for System Biology, NHLBI, National Institute of Health, Bethesda, MD, USA
| | - M Litt
- Medical Education Center, Ball State University, Muncie, IN, USA
| | - MSJ Riberio
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, FL, USA
| | - C Deng
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, FL, USA
| | - T Salz
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, FL, USA
| | - S Casada
- Medical Education Center, Ball State University, Muncie, IN, USA
| | - X Fu
- College of Life Science, Jilin University, Changchun, China
| | - Y Qiu
- Department of Anatomy and Cell Biology, College of Medicine, University of Florida, Gainesville, FL, USA
- Shands Cancer Center, College of Medicine, University of Florida, Gainesville, FL, USA
| | - K Zhao
- Center for System Biology, NHLBI, National Institute of Health, Bethesda, MD, USA
| | - S Huang
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, FL, USA
- Shands Cancer Center, College of Medicine, University of Florida, Gainesville, FL, USA
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4
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Wilkinson AC, Goode DK, Cheng YH, Dickel DE, Foster S, Sendall T, Tijssen MR, Sanchez MJ, Pennacchio LA, Kirkpatrick AM, Göttgens B. Single site-specific integration targeting coupled with embryonic stem cell differentiation provides a high-throughput alternative to in vivo enhancer analyses. Biol Open 2013; 2:1229-38. [PMID: 24244860 PMCID: PMC3828770 DOI: 10.1242/bio.20136296] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2013] [Accepted: 09/09/2013] [Indexed: 01/05/2023] Open
Abstract
Comprehensive analysis of cis-regulatory elements is key to understanding the dynamic gene regulatory networks that control embryonic development. While transgenic animals represent the gold standard assay, their generation is costly, entails significant animal usage, and in utero development complicates time-course studies. As an alternative, embryonic stem (ES) cells can readily be differentiated in a process that correlates well with developing embryos. Here, we describe a highly effective platform for enhancer assays using an Hsp68/Venus reporter cassette that targets to the Hprt locus in mouse ES cells. This platform combines the flexibility of Gateway® cloning, live cell trackability of a fluorescent reporter, low background and the advantages of single copy insertion into a defined genomic locus. We demonstrate the successful recapitulation of tissue-specific enhancer activity for two cardiac and two haematopoietic enhancers. In addition, we used this assay to dissect the functionality of the highly conserved Ets/Ets/Gata motif in the Scl+19 enhancer, which revealed that the Gata motif is not required for initiation of enhancer activity. We further confirmed that Gata2 is not required for endothelial activity of the Scl+19 enhancer using Gata2−/− Scl+19 transgenic embryos. We have therefore established a valuable toolbox to study gene regulatory networks with broad applicability.
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Affiliation(s)
- Adam C Wilkinson
- Cambridge Institute for Medical Research and Wellcome Trust-MRC Cambridge Stem Cell Institute, University of Cambridge , Hills Road, Cambridge CB2 0XY , UK
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5
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Activity of a heptad of transcription factors is associated with stem cell programs and clinical outcome in acute myeloid leukemia. Blood 2013; 121:2289-300. [PMID: 23327922 DOI: 10.1182/blood-2012-07-446120] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Aberrant transcriptional programs in combination with abnormal proliferative signaling drive leukemic transformation. These programs operate in normal hematopoiesis where they are involved in hematopoietic stem cell (HSC) proliferation and maintenance. Ets Related Gene (ERG) is a component of normal and leukemic stem cell signatures and high ERG expression is a risk factor for poor prognosis in acute myeloid leukemia (AML). However, mechanisms that underlie ERG expression in AML and how its expression relates to leukemic stemness are unknown. We report that ERG expression in AML is associated with activity of the ERG promoters and +85 stem cell enhancer and a heptad of transcription factors that combinatorially regulate genes in HSCs. Gene expression signatures derived from ERG promoter-stem cell enhancer and heptad activity are associated with clinical outcome when ERG expression alone fails. We also show that the heptad signature is associated with AMLs that lack somatic mutations in NPM1 and confers an adverse prognosis when associated with FLT3 mutations. Taken together, these results suggest that transcriptional regulators cooperate to establish or maintain primitive stem cell-like signatures in leukemic cells and that the underlying pattern of somatic mutations contributes to the development of these signatures and modulate their influence on clinical outcome.
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6
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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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7
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Spensberger D, Kotsopoulou E, Ferreira R, Broccardo C, Scott LM, Fourouclas N, Ottersbach K, Green AR, Göttgens B. Deletion of the Scl +19 enhancer increases the blood stem cell compartment without affecting the formation of mature blood lineages. Exp Hematol 2012; 40:588-598.e1. [PMID: 22401818 PMCID: PMC3387379 DOI: 10.1016/j.exphem.2012.02.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2012] [Revised: 02/11/2012] [Accepted: 02/15/2012] [Indexed: 11/29/2022]
Abstract
The stem cell leukemia (Scl)/Tal1 gene is essential for normal blood and endothelial development, and is expressed in hematopoietic stem cells (HSCs), progenitors, erythroid, megakaryocytic, and mast cells. The Scl +19 enhancer is active in HSCs and progenitor cells, megakaryocytes, and mast cells, but not mature erythroid cells. Here we demonstrate that in vivo deletion of the Scl +19 enhancer (Scl(Δ19/Δ19)) results in viable mice with normal Scl expression in mature hematopoietic lineages. By contrast, Scl expression is reduced in the stem/progenitor compartment and flow cytometry analysis revealed that the HSC and megakaryocyte-erythroid progenitor populations are enlarged in Scl(Δ19/Δ19) mice. The increase in HSC numbers contributed to enhanced expansion in bone marrow transplantation assays, but did not affect multilineage repopulation or stress responses. These results affirm that the Scl +19 enhancer plays a key role in the development of hematopoietic stem/progenitor cells, but is not necessary for mature hematopoietic lineages. Moreover, active histone marks across the Scl locus were significantly reduced in Scl(Δ19/Δ19) fetal liver cells without major changes in steady-state messenger RNA levels, suggesting post-transcriptional compensation for loss of a regulatory element, a result that might be widely relevant given the frequent observation of mild phenotypes after deletion of regulatory elements.
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Affiliation(s)
| | | | | | | | | | | | | | - Anthony R. Green
- Department of Haematology, Cambridge Institute for Medical Research, University of Cambridge, Cambridge, UK
| | - Berthold Göttgens
- Department of Haematology, Cambridge Institute for Medical Research, University of Cambridge, Cambridge, UK
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8
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Curtis DJ, Salmon JM, Pimanda JE. Concise Review: Blood Relatives: Formation and regulation of hematopoietic stem cells by the basic helix-loop-helix transcription factors stem cell leukemia and lymphoblastic leukemia-derived sequence 1. Stem Cells 2012; 30:1053-8. [DOI: 10.1002/stem.1093] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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9
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Follows GA, Ferreira R, Janes ME, Spensberger D, Cambuli F, Chaney AF, Kinston SJ, Landry JR, Green AR, Göttgens B. Mapping and functional characterisation of a CTCF-dependent insulator element at the 3' border of the murine Scl transcriptional domain. PLoS One 2012; 7:e31484. [PMID: 22396734 PMCID: PMC3291548 DOI: 10.1371/journal.pone.0031484] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2011] [Accepted: 01/09/2012] [Indexed: 11/18/2022] Open
Abstract
The Scl gene encodes a transcription factor essential for haematopoietic development. Scl transcription is regulated by a panel of cis-elements spread over 55 kb with the most distal 3′ element being located downstream of the neighbouring gene Map17, which is co-regulated with Scl in haematopoietic cells. The Scl/Map17 domain is flanked upstream by the ubiquitously expressed Sil gene and downstream by a cluster of Cyp genes active in liver, but the mechanisms responsible for delineating the domain boundaries remain unclear. Here we report identification of a DNaseI hypersensitive site at the 3′ end of the Scl/Map17 domain and 45 kb downstream of the Scl transcription start site. This element is located at the boundary of active and inactive chromatin, does not function as a classical tissue-specific enhancer, binds CTCF and is both necessary and sufficient for insulator function in haematopoietic cells in vitro. Moreover, in a transgenic reporter assay, tissue-specific expression of the Scl promoter in brain was increased by incorporation of 350 bp flanking fragments from the +45 element. Our data suggests that the +45 region functions as a boundary element that separates the Scl/Map17 and Cyp transcriptional domains, and raise the possibility that this element may be useful for improving tissue-specific expression of transgenic constructs.
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Affiliation(s)
- George A Follows
- Department of Haematology, Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom.
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10
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Schütte J, Moignard V, Göttgens B. Establishing the stem cell state: insights from regulatory network analysis of blood stem cell development. WILEY INTERDISCIPLINARY REVIEWS-SYSTEMS BIOLOGY AND MEDICINE 2012; 4:285-95. [PMID: 22334489 DOI: 10.1002/wsbm.1163] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Transcription factors (TFs) have long been recognized as powerful regulators of cell-type identity and differentiation. As TFs function as constituents of regulatory networks, identification and functional characterization of key interactions within these wider networks will be required to understand how TFs exert their powerful biological functions. The formation of blood cells (hematopoiesis) represents a widely used model system for the study of cellular differentiation. Moreover, specific TFs or groups of TFs have been identified to control the various cell fate choices that must be made when blood stem cells differentiate into more than a dozen distinct mature blood lineages. Because of the relative ease of accessibility, the hematopoietic system represents an attractive experimental system for the development of regulatory network models. Here, we review the modeling efforts carried out to date, which have already provided new insights into the molecular control of blood cell development. We also explore potential areas of future study such as the need for new high-throughput technologies and a focus on studying dynamic cellular systems. Many leukemias arise as the result of mutations that cause transcriptional dysregulation, thus suggesting that a better understanding of transcriptional control mechanisms in hematopoiesis is of substantial biomedical relevance. Moreover, lessons learned from regulatory network analysis in the hematopoietic system are likely to inform research on less experimentally tractable tissues.
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Affiliation(s)
- Judith Schütte
- Department of Haematology, Cambridge Institute for Medical Research, University of Cambridge, Cambridge, UK
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11
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Tijssen M, Cvejic A, Joshi A, Hannah R, Ferreira R, Forrai A, Bellissimo D, Oram S, Smethurst P, Wilson N, Wang X, Ottersbach K, Stemple D, Green A, Ouwehand W, Göttgens B. Genome-wide analysis of simultaneous GATA1/2, RUNX1, FLI1, and SCL binding in megakaryocytes identifies hematopoietic regulators. Dev Cell 2011; 20:597-609. [PMID: 21571218 PMCID: PMC3145975 DOI: 10.1016/j.devcel.2011.04.008] [Citation(s) in RCA: 218] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2010] [Revised: 02/28/2011] [Accepted: 04/20/2011] [Indexed: 11/20/2022]
Abstract
Hematopoietic differentiation critically depends on combinations of transcriptional regulators controlling the development of individual lineages. Here, we report the genome-wide binding sites for the five key hematopoietic transcription factors--GATA1, GATA2, RUNX1, FLI1, and TAL1/SCL--in primary human megakaryocytes. Statistical analysis of the 17,263 regions bound by at least one factor demonstrated that simultaneous binding by all five factors was the most enriched pattern and often occurred near known hematopoietic regulators. Eight genes not previously appreciated to function in hematopoiesis that were bound by all five factors were shown to be essential for thrombocyte and/or erythroid development in zebrafish. Moreover, one of these genes encoding the PDZK1IP1 protein shared transcriptional enhancer elements with the blood stem cell regulator TAL1/SCL. Multifactor ChIP-Seq analysis in primary human cells coupled with a high-throughput in vivo perturbation screen therefore offers a powerful strategy to identify essential regulators of complex mammalian differentiation processes.
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Affiliation(s)
- Marloes R. Tijssen
- Department of Haematology, Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, UK
- Department of Haematology, NHS Blood and Transplant Centre, University of Cambridge, Cambridge CB2 0PT, UK
| | - Ana Cvejic
- Department of Haematology, NHS Blood and Transplant Centre, University of Cambridge, Cambridge CB2 0PT, UK
- Wellcome Trust Sanger Institute, Hinxton, Cambridge CB10 1SA, UK
| | - Anagha Joshi
- Department of Haematology, Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, UK
| | - Rebecca L. Hannah
- Department of Haematology, Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, UK
| | - Rita Ferreira
- Department of Haematology, Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, UK
| | - Ariel Forrai
- Department of Haematology, Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, UK
| | - Dana C. Bellissimo
- Department of Haematology, NHS Blood and Transplant Centre, University of Cambridge, Cambridge CB2 0PT, UK
- Wellcome Trust Sanger Institute, Hinxton, Cambridge CB10 1SA, UK
| | - S. Helen Oram
- Department of Haematology, Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, UK
| | - Peter A. Smethurst
- Department of Haematology, NHS Blood and Transplant Centre, University of Cambridge, Cambridge CB2 0PT, UK
| | - Nicola K. Wilson
- Department of Haematology, Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, UK
| | - Xiaonan Wang
- Department of Haematology, Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, UK
| | - Katrin Ottersbach
- Department of Haematology, Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, UK
| | - Derek L. Stemple
- Wellcome Trust Sanger Institute, Hinxton, Cambridge CB10 1SA, UK
| | - Anthony R. Green
- Department of Haematology, Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, UK
| | - Willem H. Ouwehand
- Department of Haematology, NHS Blood and Transplant Centre, University of Cambridge, Cambridge CB2 0PT, UK
- Wellcome Trust Sanger Institute, Hinxton, Cambridge CB10 1SA, UK
| | - Berthold Göttgens
- Department of Haematology, Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, UK
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12
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Hannah R, Joshi A, Wilson NK, Kinston S, Göttgens B. A compendium of genome-wide hematopoietic transcription factor maps supports the identification of gene regulatory control mechanisms. Exp Hematol 2011; 39:531-41. [PMID: 21338655 DOI: 10.1016/j.exphem.2011.02.009] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2011] [Revised: 02/09/2011] [Accepted: 02/14/2011] [Indexed: 12/20/2022]
Abstract
OBJECTIVE Key regulators of blood stem cell differentiation into the various mature hematopoietic lineages are commonly encoded by transcription factor genes. Elucidation of transcriptional regulatory mechanisms therefore holds great promise in advancing our understanding of both normal and malignant hematopoiesis. Recent technological advances have enabled the generation of genome-wide transcription factor binding maps using chromatin immunoprecipitation coupled with high-throughput sequencing (ChIP-Seq). However, transcription factors operate in a combinatorial fashion suggesting that integrated analysis of genome-wide maps for multiple transcription factors will be essential to fully exploit these new genome-scale data sets. MATERIALS AND METHODS Here we have generated a compendium that integrates 53 ChIP-Seq studies covering 30 factors across all major hematopoietic lineages with a total of 754,380 binding peaks. We also used transgenic mouse assays to validate a newly predicted transcriptional enhancer. RESULTS Integrated analysis of all 53 ChIP-Seq studies demonstrated that cell-type identity exerts a larger influence on global transcription factor binding patterns than the nature of the individual transcription factors. Furthermore, regions highlighted by multifactor binding within specific gene loci overlap with known regulatory elements and also provide a useful guide for identifying novel elements, as demonstrated by transgenic analysis of a previously unrecognized enhancer in the Maml3 gene locus. CONCLUSIONS The ChIP-Seq compendium described here provides a valuable resource for the wider research community by accelerating the discovery of transcriptional mechanisms operating in the hematopoietic system.
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Affiliation(s)
- Rebecca Hannah
- University of Cambridge, Department of Haematology, Cambridge Institute for Medical Research, Hills Road, Cambridge, UK
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13
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Maximum parsimony analysis of gene expression profiles permits the reconstruction of developmental cell lineage trees. Dev Biol 2011; 353:440-7. [PMID: 21354129 DOI: 10.1016/j.ydbio.2011.02.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2010] [Revised: 02/07/2011] [Accepted: 02/16/2011] [Indexed: 12/13/2022]
Abstract
Spatiotemporal control of gene expression lies at the heart of generating several hundred distinct cell types required for the development of higher order animals. Different cell types within complex organs are often characterised by means of genome-wide gene expression profiling, but analogous information for early developmental as well as adult stem and progenitor cells is largely missing because their identity is commonly unknown or they are present in prohibitively small numbers. Here we show that maximum parsimony approaches previously used to reconstruct evolutionary trees from gene content of extant species can be adapted to reconstruct cellular hierarchies both during development and steady state homeostasis of complex mammalian tissues. Using haematopoiesis as a model, we show that developmental trees reconstructed from expression profiles of mature cells are not only consistent with current experimentally validated trees but also have predictive value in determining progenitor cell specific transcriptional programmes and lineage determining transcription factors. Subsequent analysis across diverse developmental systems such as neuronal development and endoderm organogenesis demonstrated that maximum parsimony-based reconstruction of developmental trees represents a widely applicable approach to infer developmental pathways as well as the transcriptional control mechanisms underlying cell fate specification.
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14
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Wilson NK, Calero-Nieto FJ, Ferreira R, Göttgens B. Transcriptional regulation of haematopoietic transcription factors. Stem Cell Res Ther 2011; 2:6. [PMID: 21345252 PMCID: PMC3092146 DOI: 10.1186/scrt47] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The control of differential gene expression is central to all metazoan biology. Haematopoiesis represents one of the best understood developmental systems where multipotent blood stem cells give rise to a range of phenotypically distinct mature cell types, all characterised by their own distinctive gene expression profiles. Small combinations of lineage-determining transcription factors drive the development of specific mature lineages from multipotent precursors. Given their powerful regulatory nature, it is imperative that the expression of these lineage-determining transcription factors is under tight control, a fact underlined by the observation that their misexpression commonly leads to the development of leukaemia. Here we review recent studies on the transcriptional control of key haematopoietic transcription factors, which demonstrate that gene loci contain multiple modular regulatory regions within which specific regulatory codes can be identified, that some modular elements cooperate to mediate appropriate tissue-specific expression, and that long-range approaches will be necessary to capture all relevant regulatory elements. We also explore how changes in technology will impact on this area of research in the future.
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Affiliation(s)
- Nicola K Wilson
- University of Cambridge Department of Haematology, Cambridge Institute for Medical Research, Hills Road, Cambridge, CB2 0XY, UK.
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15
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Abstract
Development progresses through a sequence of cellular identities which are determined by the activities of networks of transcription factor genes. Alterations in cis-regulatory elements of these genes play a major role in evolutionary change, but little is known about the mechanisms responsible for maintaining conserved patterns of gene expression. We have studied the evolution of cis-regulatory mechanisms controlling the SCL gene, which encodes a key transcriptional regulator of blood, vasculature, and brain development and exhibits conserved function and pattern of expression throughout vertebrate evolution. SCL cis-regulatory elements are conserved between frog and chicken but accrued alterations at an accelerated rate between 310 and 200 million years ago, with subsequent fixation of a new cis-regulatory pattern at the beginning of the mammalian radiation. As a consequence, orthologous elements shared by mammals and lower vertebrates exhibit functional differences and binding site turnover between widely separated cis-regulatory modules. However, the net effect of these alterations is constancy of overall regulatory inputs and of expression pattern. Our data demonstrate remarkable cis-regulatory remodelling across the SCL locus and indicate that stable patterns of expression can mask extensive regulatory change. These insights illuminate our understanding of vertebrate evolution.
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16
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Ottersbach K, Smith A, Wood A, Göttgens B. Ontogeny of haematopoiesis: recent advances and open questions. Br J Haematol 2009; 148:343-55. [PMID: 19863543 DOI: 10.1111/j.1365-2141.2009.07953.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Unravelling the embryonic origins of the haematopoietic system has been the subject of sustained research for more than a century. Nevertheless, many important questions are still either unanswered or remain a matter of intense debate. Recent progress in mouse and embryonic stem cell model systems as well as imaging and post-genomic technologies has provided new insights into many of these open questions. Here we place into context recent reports on the anatomical site of blood stem cell emergence and, using red blood cells as an example, illustrate how the development of stem cells and the other blood lineages is both temporally and spatially decoupled. In addition, we outline how embryonic stem cell assays are increasingly used as a powerful surrogate for studying lineage relationships and developmental potential of early embryonic blood progenitors. Finally, we review how recent progress in the reconstruction of transcriptional regulatory networks is beginning to define the connectivity between key regulators that control early blood development. In light of these rapid recent advances, research into the embryonic origins of the haematopoietic system should remain one of the most vibrant disciplines within the wider field of haematology for the foreseeable future.
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Affiliation(s)
- Katrin Ottersbach
- Department of Haematology, Cambridge Institute for Medical Research, University of Cambridge, Cambridge, UK
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17
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Foster SD, Oram SH, Wilson NK, Göttgens B. From genes to cells to tissues--modelling the haematopoietic system. MOLECULAR BIOSYSTEMS 2009; 5:1413-20. [PMID: 19763334 DOI: 10.1039/b907225j] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Haematopoiesis (or blood formation) in general and haematopoietic stem cells more specifically represent some of the best studied mammalian developmental systems. Sophisticated purification protocols coupled with powerful biological assays permit functional analysis of highly purified cell populations both in vitro and in vivo. However, despite several decades of intensive research, the sheer complexity of the haematopoietic system means that many important questions remain unanswered or even unanswerable with current experimental tools. Scientists have therefore increasingly turned to modelling to tackle complexity at multiple levels ranging from networks of genes to the behaviour of cells and tissues. Early modelling attempts of gene regulatory networks have focused on core regulatory circuits but have more recently been extended to genome-wide datasets such as expression profiling and ChIP-sequencing data. Modelling of haematopoietic cells and tissues has provided insight into the importance of phenotypic heterogeneity for the differentiation of normal progenitor cells as well as a greater understanding of treatment response for particular pathologies such as chronic myeloid leukaemia. Here we will review recent progress in attempts to reconstruct segments of the haematopoietic system. A variety of modelling strategies will be covered from small-scale, protein-DNA or protein-protein interactions to large scale reconstructions. Also discussed will be examples of how stochastic modelling may be applied to multi cell systems such as those seen in normal and malignant haematopoiesis.
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Affiliation(s)
- Samuel D Foster
- Haematopoietic Stem Cell Laboratory, Cambridge Institute for Medical Research, Wellcome Trust/MRC Building, Hills Rd, Cambridge, CB2 0XY
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18
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Cerisoli F, Cassinelli L, Lamorte G, Citterio S, Bertolotti F, Magli MC, Ottolenghi S. Green fluorescent protein transgene driven by Kit regulatory sequences is expressed in hematopoietic stem cells. Haematologica 2009; 94:318-25. [PMID: 19181779 DOI: 10.3324/haematol.13689] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
BACKGROUND The transcriptional regulation of stem cell genes is still poorly understood. Kit, encoding the stem cell factor receptor, is a pivotal molecule for multiple types of stem/progenitor cells. We previously generated mouse lines expressing transgenic green fluorescent protein under the control of Kit promoter/first intron regulatory elements, and we demonstrated expression in hematopoietic progenitors. DESIGN AND METHODS In the present work we investigated whether the transgene is also expressed in hematopoietic stem cells of adult bone marrow and fetal liver. To this purpose, we tested, in long-term repopulating assays, cell fractions expressing different levels of green fluorescent protein within Kit-positive or SLAM-selected populations. RESULTS The experiments demonstrated transgene expression in both fetal and adult hematopoietic stem cells and indicated that the transgene is transcribed at distinctly lower levels in hematopoietic stem cells than in pluripotent and committed progenitors. CONCLUSIONS These results, together with previous data, show that a limited subset of DNA sequences drives gene expression in number of stem cell types (hematopoietic stem cells, primordial germ cells, cardiac stem cells). Additionally, our results might help to further improve high level purification of hematopoietic stem cells for experimental purposes. Finally, as the Kit/green fluorescent protein transgene is expressed in multiple stem cell types, our transgenic model provides powerful in vivo system to track these cells during development and tissue regeneration.
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Affiliation(s)
- Francesco Cerisoli
- Institute of Biomedical Technologies, National Council of Research, Pisa, Italy
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19
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Expression of the leukemia oncogene Lmo2 is controlled by an array of tissue-specific elements dispersed over 100 kb and bound by Tal1/Lmo2, Ets, and Gata factors. Blood 2009; 113:5783-92. [PMID: 19171877 DOI: 10.1182/blood-2008-11-187757] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
The Lmo2 gene encodes a transcriptional cofactor critical for the development of hematopoietic stem cells. Ectopic LMO2 expression causes leukemia in T-cell acute lymphoblastic leukemia (T-ALL) patients and severe combined immunodeficiency patients undergoing retroviral gene therapy. Tightly controlled Lmo2 expression is therefore essential, yet no comprehensive analysis of Lmo2 regulation has been published so far. By comparative genomics, we identified 17 highly conserved noncoding elements, 9 of which revealed specific acetylation marks in chromatin-immunoprecipitation and microarray (ChIP-chip) assays performed across 250 kb of the Lmo2 locus in 11 cell types covering different stages of hematopoietic differentiation. All candidate regulatory regions were tested in transgenic mice. An extended LMO2 proximal promoter fragment displayed strong endothelial activity, while the distal promoter showed weak forebrain activity. Eight of the 15 distal candidate elements functioned as enhancers, which together recapitulated the full expression pattern of Lmo2, directing expression to endothelium, hematopoietic cells, tail, and forebrain. Interestingly, distinct combinations of specific distal regulatory elements were required to extend endothelial activity of the LMO2 promoter to yolk sac or fetal liver hematopoietic cells. Finally, Sfpi1/Pu.1, Fli1, Gata2, Tal1/Scl, and Lmo2 were shown to bind to and transactivate Lmo2 hematopoietic enhancers, thus identifying key upstream regulators and positioning Lmo2 within hematopoietic regulatory networks.
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20
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Garcia-Ortega A, Cañete A, Quintero C, Silberstein L, Gil MP, Alvarez-Dolado M, Dekel B, Gottgens B, Sanchez M. Enhanced Hemato-Vascular Contribution Of SCL-3′Enh Expressing Fetal Liver Cells Uncovers Their Potential To Integrate In Extra-Medullary Adult Niches. Stem Cells 2009; 28:100-12. [DOI: 10.1002/stem.228] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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21
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Miranda-Saavedra D, Göttgens B. Transcriptional regulatory networks in haematopoiesis. Curr Opin Genet Dev 2008; 18:530-5. [PMID: 18838119 DOI: 10.1016/j.gde.2008.09.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2008] [Revised: 08/29/2008] [Accepted: 09/09/2008] [Indexed: 10/21/2022]
Abstract
The coordinated expression of genes lies at the heart of developmental programmes, with complex regulatory networks controlling the spatial and temporal aspects of gene expression. Haematopoiesis (blood formation) has long served as a model process for studying the specification and subsequent differentiation of stem cells and represents the best characterised adult stem cell system. In this review, we outline how the integration of experimental and computational approaches as applied to haematopoiesis has resulted in some of the most advanced models of transcriptional regulatory networks in mammals.
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Affiliation(s)
- Diego Miranda-Saavedra
- Department of Haematology, Cambridge Institute for Medical Research, University of Cambridge, Cambridge, UK
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22
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Sausville J, Molinolo AA, Cheng X, Frampton J, Takebe N, Gutkind JS, Feldman RA. RCAS/SCL-TVA animal model allows targeted delivery of polyoma middle T oncogene to vascular endothelial progenitors in vivo and results in hemangioma development. Clin Cancer Res 2008; 14:3948-55. [PMID: 18559617 DOI: 10.1158/1078-0432.ccr-07-5152] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE To recapitulate the generation of cancer stem cells in the context of an intact animal using a retroviral vector capable of in vivo delivery of oncogenes to primitive endothelial and hematopoietic stem cells. EXPERIMENTAL DESIGN Targeting of these progenitors was achieved using transgenic mice in which the avian TVA retroviral receptor was placed under the control of the stem cell leukemia (scl/tal-1) gene promoter and SCL +19 enhancer. RESULTS Injection of an avian retrovirus encoding polyoma middle T (PyMT), an oncogene that transforms endothelial cells, caused rapid lethality in all SCL-TVA mice but not in control TVA(-) littermates. The infected animals exhibited hemorrhagic foci in several organs. Histopathologic analysis confirmed the presence of hemangiomas and the endothelial origin of the PyMT-transformed cells. Surprisingly, the transformed endothelial cells contained readily detectable numbers of TVA(+) cells. By contrast, normal blood vessels had very few of these cells. The presence of TVA(+) cells in the lesions suggests that the cells originally infected by PyMT retained stem cell characteristics. Further analysis showed that the tumor cells exhibited activation of the phosphatidylinositol 3-kinase/Akt and S6/mammalian target of rapamycin pathways, suggesting a mechanism used by PyMT to transform endothelial progenitors in vivo. CONCLUSIONS We conclude that this experimental system can specifically deliver oncogenes to vascular endothelial progenitors in vivo and cause a fatal neoplastic disease. This animal model should allow the generation of endothelial cancer stem cells in the natural environment of an immunocompetent animal, thereby enabling the recapitulation of genetic alterations that are responsible for the initiation and progression of human malignancies of endothelial origin.
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Affiliation(s)
- Justin Sausville
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, Maryland, USA
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23
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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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24
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Abstract
Transcription factors such as Scl/Tal1, Lmo2, and Runx1 are essential for the development of hematopoietic stem cells (HSCs). However, the precise mechanisms by which these factors interact to form transcriptional networks, as well as the identity of the genes downstream of these regulatory cascades, remain largely unknown. To this end, we generated an Scl(-/-) yolk sac cell line to identify candidate Scl target genes by global expression profiling after reintroduction of a TAT-Scl fusion protein. Bioinformatics analysis resulted in the identification of 9 candidate Scl target transcription factor genes, including Runx1 and Runx3. Chromatin immunoprecipitation confirmed that both Runx genes are direct targets of Scl in the fetal liver and that Runx1 is also occupied by Scl in the yolk sac. Furthermore, binding of an Scl-Lmo2-Gata2 complex was demonstrated to occur on the regions flanking the conserved E-boxes of the Runx1 loci and was shown to transactivate the Runx1 element. Together, our data provide a key component of the transcriptional network of early hematopoiesis by identifying downstream targets of Scl that can explain key aspects of the early Scl(-/-) phenotype.
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25
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Dekel B, Metsuyanim S, Garcia AM, Quintero C, Sanchez MJ, Izraeli S. Organ-injury-induced reactivation of hemangioblastic precursor cells. Leukemia 2007; 22:103-13. [PMID: 17898790 DOI: 10.1038/sj.leu.2404941] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Early in mammalian development, the stem cell leukemia (SCL/TAL1) gene and its distinct 3' enhancer (SCL 3'En) specify bipotential progenitor cells that give rise to blood and endothelium, thus termed hemangioblasts. We have previously detected a minor population of SCL (+) cells in the postnatal kidney. Here, we demonstrate that cells expressing the SCL 3'En in the adult kidney are comprised of CD45+CD31- hematopoietic cells, CD45-CD31+ endothelial cells and CD45-CD31- interstitial cells. Creation of bone marrow chimeras of SCL 3'En transgenic mice into wild-type hosts shows that all three types of SCL 3'En-expressing cells in the adult kidney can originate from the bone marrow. Ischemia/reperfusion injury to the adult kidney of SCL 3'En transgenic mice results in the intrarenal elevation of SCL and FLK1 mRNA levels and of cells expressing hem-endothelial progenitor markers (CD45, CD34, c-Kit and FLK1). Furthermore, analysis of SCL 3'En in the ischemic kidneys reveals an increase in the abundance of SCL 3'En-expressing cells, predominantly within the CD45 (+) hematopoietic fraction and to a lesser extent in the CD45 (-) fraction. Our results suggest organ-injury-induced reactivation of bone marrow-derived hemangioblasts and possible local angioblastic progenitors expressing SCL and SCL 3'En.
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Affiliation(s)
- B Dekel
- Department of Pediatrics and Laboratory of Regenerative Nephrology, Edmond and Lili Safra Children's Hospital, Sheba Medical Center, Tel Hashomer, Israel.
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26
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Ogilvy S, Ferreira R, Piltz SG, Bowen JM, Göttgens B, Green AR. The SCL +40 enhancer targets the midbrain together with primitive and definitive hematopoiesis and is regulated by SCL and GATA proteins. Mol Cell Biol 2007; 27:7206-19. [PMID: 17709394 PMCID: PMC2168913 DOI: 10.1128/mcb.00931-07] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The SCL/Tal-1 gene encodes a basic helix-loop-helix transcription factor with key roles in hematopoietic and neural development. SCL is expressed in, and required for, both primitive and definitive erythropoiesis. Thus far, we have identified only one erythroid SCL enhancer. Located 40 kb downstream of exon 1a, the +40 enhancer displays activity in primitive erythroblasts. We demonstrate here that a 3.7-kb fragment containing this element also targets expression to the midbrain, a known site of endogenous SCL expression. Although the 3.7-kb construct was active in primitive, but not definitive, erythroblasts, a larger 5.0-kb fragment, encompassing the 3.7-kb region, was active in both fetal and adult definitive hematopoietic cells. This included Ter119+ erythroid cells along with fetal liver erythroid and myeloid progenitors. Unlike two other SCL hematopoietic enhancers (+18/19 and -4), +40 enhancer transgenes were inactive in the endothelium. A conserved 400-bp core region, essential for both hematopoietic and midbrain +40 enhancer activity in embryos, relied on two GATA/E-box motifs and was bound in vivo by GATA-1 and SCL in erythroid cells. These results suggest a model in which the SCL +18/19 and/or -4 enhancers initiate SCL expression in early mesodermal derivatives capable of generating blood and endothelium, with subsequent activation of the +40 enhancer via an autoregulatory loop.
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Affiliation(s)
- S Ogilvy
- Department of Haematology, Cambridge Institute for Medical Research, University of Cambridge, Hills Road, Cambridge CB2 0XY, United Kingdom
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27
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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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28
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Mollica LR, Crawley JTB, Liu K, Rance JB, Cockerill PN, Follows GA, Landry JR, Wells DJ, Lane DA. Role of a 5′-enhancer in the transcriptional regulation of the human endothelial cell protein C receptor gene. Blood 2006; 108:1251-9. [PMID: 16627757 DOI: 10.1182/blood-2006-02-001461] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
AbstractThe endothelial cell protein C receptor (EPCR) is expressed by endothelial cells of large blood vessels and by hematopoietic stem cells. DNaseI hypersensitive (DH) site mapping across 38 kb of the human EPCR gene (hEPCR) locus identified 3 potential regulatory elements. By itself, the DH region spanning the proximal promoter (PP) was unable to direct cell-specific transcription in transgenic mice. A second DH element, located upstream of PP and termed –5.5HS was hypersensitive only in endothelial cells (ECs) and immature hematopoietic cell lines. Transgenes expressing LacZ under the control of –5.5HS coupled to either PP or the SV40 promoter were able to direct β-galactosidase activity to the endothelium of large vessels during embryogenesis and adulthood. The –5.5HS exhibited enhancer activity that was conferred by the interplay of transcription factors interacting with conserved Ets and composite GATA/Tal1 motifs. The third DH element, located in intron 2, was primarily hypersensitive in EPCR-negative cells, and capable of initiating antisense transcription, suggesting a role in hEPCR silencing. This study identifies critical elements required for the tissue specificity of hEPCR and suggests a mechanism for endothelial and hematopoietic stem cell–specific transcriptional regulation that reflects the common origin of these cell types.
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29
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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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30
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Pimanda JE, Silberstein L, Dominici M, Dekel B, Bowen M, Oldham S, Kallianpur A, Brandt SJ, Tannahill D, Göttgens B, Green AR. Transcriptional link between blood and bone: the stem cell leukemia gene and its +19 stem cell enhancer are active in bone cells. Mol Cell Biol 2006; 26:2615-25. [PMID: 16537906 PMCID: PMC1430329 DOI: 10.1128/mcb.26.7.2615-2625.2006] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Blood and vascular cells are generated during early embryogenesis from a common precursor, the hemangioblast. The stem cell leukemia gene (SCL/tal 1) encodes a basic helix-loop-helix transcription factor that is essential for the normal development of blood progenitors and blood vessels. We have previously characterized a panel of SCL enhancers including the +19 element, which directs expression to hematopoietic stem cells and endothelium. Here we demonstrate that SCL is expressed in bone primordia during embryonic development and in adult osteoblasts. Despite consistent expression in cells of the osteogenic lineage, SCL protein is not required for bone specification of embryonic stem cells. In transgenic mice, the SCL +19 core enhancer directed reporter gene expression to vascular smooth muscle and bone in addition to blood and endothelium. A 644-bp fragment containing the SCL +19 core enhancer was active in both blood and bone cell lines and was bound in vivo by a common array of Ets and GATA transcription factors. Taken together with the recent observation that a common progenitor can give rise to blood and bone cells, our results suggest that the SCL +19 enhancer targets a mesodermal progenitor capable of generating hematopoietic, vascular, and osteoblastic progeny.
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Affiliation(s)
- John E Pimanda
- Department of Haematology, Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 2XY, United Kingdom
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