Early Lineage Priming by Trisomy of Erg Leads to Myeloproliferation in a Down Syndrome Model

RESEARCH ARTICLE Early Lineage Priming by Trisomy of Erg Leads to Myeloproliferation in a Down Syndrome Model Ashley P. Ng1,2*, Yifang Hu1, Donald Metcalf1,2, Craig D. Hyland1, Helen Ierino1, Belinda Phipson1,3, Di Wu4,5, Tracey M. Baldwin1, Maria Kauppi1,2, Hiu Kiu1,2, Ladina Di Rago1, Douglas J. Hilton1,2, Gordon K. Smyth1,3, Warren S. Alexander1,2 1 The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia, 2 Department of Medical Biology, The University of Melbourne, Parkville, Victoria, Australia, 3 Department of Mathematics and Statistics, The University of Melbourne, Parkville, Victoria, Australia, 4 Centre for Cancer Research, Monash Institute of Medical Research, Monash University, Clayton, Victoria, Australia, 5 Department of Statistics, Harvard University, Cambridge, Massachusetts, United States of America * OPEN ACCESS Citation: Ng AP, Hu Y, Metcalf D, Hyland CD, Ierino H, Phipson B, et al. (2015) Early Lineage Priming by Trisomy of Erg Leads to Myeloproliferation in a Down Syndrome Model. PLoS Genet 11(5): e1005211. doi:10.1371/journal.pgen.1005211 Editor: H. Leighton Grimes, Cincinnati Children's Hospital Medical Center, UNITED STATES Received: September 3, 2014 Accepted: April 13, 2015 Published: May 14, 2015 Copyright: © 2015 Ng et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Data Availability Statement: All relevant data are within the paper and its Supporting Information files. All microarray files are available from the Array Express database, www.ebi.ac.uk/arrayexpress (accession no. E-MTAB-2574). Funding: This work was supported by Program and Project Grants (1016647, 1054618), Fellowships (WSA 575501, GKS 1058892), and Independent Research Institutes Infrastructure Support Scheme Grant (361646) from the Australian National Health and Medical Research Council (https://www.nhmrc. gov.au), the Carden Fellowship (DM) of the Cancer Council, Victoria (http://www.cancervic.org.au), the Abstract Down syndrome (DS), with trisomy of chromosome 21 (HSA21), is the commonest human aneuploidy. Pre-leukemic myeloproliferative changes in DS foetal livers precede the acquisition of GATA1 mutations, transient myeloproliferative disorder (DS-TMD) and acute megakaryocytic leukemia (DS-AMKL). Trisomy of the Erg gene is required for myeloproliferation in the Ts(1716)65Dn DS mouse model. We demonstrate here that genetic changes specifically attributable to trisomy of Erg lead to lineage priming of primitive and early multipotential progenitor cells in Ts(1716)65Dn mice, excess megakaryocyte-erythroid progenitors, and malignant myeloproliferation. Gene expression changes dependent on trisomy of Erg in Ts (1716)65Dn multilineage progenitor cells were correlated with those associated with trisomy of HSA21 in human DS hematopoietic stem and primitive progenitor cells. These data suggest a role for ERG as a regulator of hematopoietic lineage potential, and that trisomy of ERG in the context of DS foetal liver hemopoiesis drives the pre-leukemic changes that predispose to subsequent DS-TMD and DS-AMKL. Author Summary An excess number of genes in trisomy on human chromosome 21 leads to the development of specific diseases in human Down syndrome. An excess copy of the gene, ERG, an ETS family transcription factor, has been implicated in abnormal blood system development in Down syndrome. In this study we show how trisomy of Erg in a murine Down syndrome model perturbs hematopoietic progenitor cells in a manner similar to that observed in human Down syndrome by inducing gene expression changes and lineage priming in early multi-potential progenitors. We show that the gene expression signature specifically attributable to trisomy of Erg in the murine model is strongly correlated with PLOS Genetics | DOI:10.1371/journal.pgen.1005211 May 14, 2015 1 / 19 Genetic Consequences Erg Trisomy in Down Syndrome Cure Cancer Australia (www.cure.org.au/)/Leukaemia Foundation Australia (www.leukaemia.org.au/) Post Doctoral Fellowship and Lions Fellowship, Cancer Council of Victoria (APN), the Australian Cancer Research Fund (http://acrf.com.au) and Victorian State Government Operational Infrastructure Support (www.vic.gov.au). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have declared that no competing interests exist. gene expression changes in human Down syndrome hematopoietic cells. The data suggest that Erg is an important regulator of megakaryocyte-erythroid lineage specification in multipotential hematopoietic cells and that trisomy of Erg in the context of DS prediposes to a transient myeloproliferative disorder and acute megakaryocyte leukaemia in a multistep model of leukemogenesis. Introduction Down syndrome (DS) is the commonest human aneuploidy [1]. DS infants with trisomy of human chromosome 21 (HSA21) are uniquely predisposed to a transient myeloproliferative disorder (DS-TMD) and acute megakaryocytic leukemia (DS-AMKL) [2]. DS-TMD, usually characterised by the presence of peripheral immature myeloblasts/megakaryoblasts and the variable involvement of other organs, is restricted to the neonatal period, spontaneously regresses and is the result of genetic co-operation between trisomy of HSA21 gene(s) with an acquired somatic mutation in GATA1 in virtually all cases [3]. However, up to 30% of children will subsequently develop DS-AMKL, a malignancy clonally related to the preceding DS-TMD. Candidate gene analysis and genome-wide exome sequencing have identified somatic mutations and deletions implicated in the progression of DS-TMD to DS-AMKL, in genes including JAK1, JAK2, JAK3, FLT3, TP53, TRIB1, MPL, EZH2, APC, PARK-2, PACRG, EXT1, DLEC1 and SMC3, and further suggested that GATA-1 mutations alone in the context of HSA21 trisomy were sufficient for development of DS-TMD [4–12]. Preceding acquisition of GATA1 mutations, human DS foetal livers exhibit perturbed hematopoiesis. Increased numbers and clonogenicity of hematopoietic stem (HSC) and progenitor cells, increased frequency of bi-potential megakaryocyte-erythroid progenitors, and reduced numbers of granulocyte-macrophage-committed progenitor cells have been described [13–15]. This perturbation must be attributed to a specific trisomic gene or genes on HSA21 that drive the pre-leukemic DS phenotype from which DS-AMKL and DS-TMD subsequently arise. Murine DS models with germline transmissible segmental trisomies of human or murine orthologues of HSA21 genes have allowed genetic analyses of the contributions of genes within the DS critical interval to specific DS phenotypes [16–19]. A well studied model is the Ts(1716)65Dn mouse, which is trisomic for orthologs of ~104 human chromoso (...truncated)