ORCID Profile
0000-0001-6302-5705
Current Organisation
University of Cambridge
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Publisher: Informa UK Limited
Date: 03-2004
Publisher: American Society of Hematology
Date: 22-12-2011
Publisher: Informa UK Limited
Date: 12-2010
DOI: 10.1128/MCB.00870-10
Publisher: Informa UK Limited
Date: 12-2011
DOI: 10.1128/MCB.05830-11
Publisher: Informa UK Limited
Date: 03-2013
DOI: 10.1128/MCB.01525-12
Publisher: Elsevier BV
Date: 08-2015
Publisher: American Society of Hematology
Date: 28-05-2009
DOI: 10.1182/BLOOD-2009-01-200048
Abstract: The basic helix-loop-helix transcription factor Scl/Tal1 controls the development and subsequent differentiation of hematopoietic stem cells (HSCs). However, because few Scl target genes have been validated to date, the underlying mechanisms have remained largely unknown. In this study, we have used ChIP-Seq technology (coupling chromatin immunoprecipitation with deep sequencing) to generate a genome-wide catalog of Scl-binding events in a stem rogenitor cell line, followed by validation using primary fetal liver cells and comprehensive transgenic mouse assays. Transgenic analysis provided in vivo validation of multiple new direct Scl target genes and allowed us to reconstruct an in vivo validated network consisting of 17 factors and their respective regulatory elements. By coupling ChIP-Seq in model cell lines with in vivo transgenic validation and sophisticated bioinformatic analysis, we have identified a widely applicable strategy for the reconstruction of stem cell regulatory networks in which biologic material is otherwise limiting. Moreover, in addition to revealing multiple previously unrecognized links to known HSC regulators, as well as novel links to genes not previously implicated in HSC function, comprehensive transgenic analysis of regulatory elements provided substantial new insights into the transcriptional control of several important hematopoietic regulators, including Cbfa2t3h/Eto2, Cebpe, Nfe2, Zfpm1/Fog1, Erg, Mafk, Gfi1b, and Myb.
Publisher: Springer Science and Business Media LLC
Date: 10-01-2013
DOI: 10.1038/LEU.2013.2
Publisher: Springer Science and Business Media LLC
Date: 27-09-2009
DOI: 10.1038/NATURE08448
Publisher: American Society of Hematology
Date: 13-10-2016
DOI: 10.1182/BLOOD-2016-02-697870
Abstract: ENG regulatory elements target hemogenic mesoderm and hemogenic endothelium. Hemogenic progenitors can be enriched using these elements as molecular probes to discover novel regulators of hematopoiesis.
Publisher: Public Library of Science (PLoS)
Date: 03-2012
Publisher: Public Library of Science (PLoS)
Date: 28-01-2011
Publisher: Springer Science and Business Media LLC
Date: 10-2017
DOI: 10.1038/NATURE24052
Publisher: American Society of Hematology
Date: 07-05-2009
DOI: 10.1182/BLOOD-2008-06-162958
Abstract: Hematopoiesis is a carefully controlled process that is regulated by complex networks of transcription factors that are, in part, controlled by signals resulting from ligand binding to cell-surface receptors. To further understand hematopoiesis, we have compared gene expression profiles of human erythroblasts, megakaryocytes, B cells, cytotoxic and helper T cells, natural killer cells, granulocytes, and monocytes using whole genome microarrays. A bioinformatics analysis of these data was performed focusing on transcription factors, immunoglobulin superfamily members, and lineage-specific transcripts. We observed that the numbers of lineage-specific genes varies by 2 orders of magnitude, ranging from 5 for cytotoxic T cells to 878 for granulocytes. In addition, we have identified novel coexpression patterns for key transcription factors involved in hematopoiesis (eg, GATA3-GFI1 and GATA2-KLF1). This study represents the most comprehensive analysis of gene expression in hematopoietic cells to date and has identified genes that play key roles in lineage commitment and cell function. The data, which are freely accessible, will be invaluable for future studies on hematopoiesis and the role of specific genes and will also aid the understanding of the recent genome-wide association studies.
Publisher: Springer Science and Business Media LLC
Date: 08-09-2021
Publisher: American Association for the Advancement of Science (AAAS)
Date: 26-06-2015
Abstract: Chromosomal DNA comes in two flavors—euchromatin, which contains most of the expressed genes, and heterochromatin, which usually remains quiet. But what keeps genes within heterochromatin silent? Tchasovnikarova et al. examined the basis for this type of silencing in mammalian cells (see the Perspective by Brummelk ). They identified a complex of proteins in human cells they called HUSH that kept particular parts of the genome silent by changing associated histone methylation marks. Science , this issue p. 1481 , see also p. 1433
Publisher: Springer Science and Business Media LLC
Date: 09-08-2013
DOI: 10.1038/LEU.2013.234
Abstract: Small molecule inhibition of the BET family of proteins, which bind acetylated lysines within histones, has been shown to have a marked therapeutic benefit in pre-clinical models of mixed lineage leukemia (MLL) fusion protein-driven leukemias. Here, we report that I-BET151, a highly specific BET family bromodomain inhibitor, leads to growth inhibition in a human erythroleukemic (HEL) cell line as well as in erythroid precursors isolated from polycythemia vera patients. One of the genes most highly downregulated by I-BET151 was LMO2, an important oncogenic regulator of hematopoietic stem cell development and erythropoiesis. We previously reported that LMO2 transcription is dependent upon Janus kinase 2 (JAK2) kinase activity in HEL cells. Here, we show that the transcriptional changes induced by a JAK2 inhibitor (TG101209) and I-BET151 in HEL cells are significantly over-lapping, suggesting a common pathway of action. We generated JAK2 inhibitor resistant HEL cells and showed that these retain sensitivity to I-BET151. These data highlight I-BET151 as a potential alternative treatment against myeloproliferative neoplasms driven by constitutively active JAK2 kinase.
Publisher: Cold Spring Harbor Laboratory
Date: 15-03-2021
DOI: 10.1101/2021.03.09.21253012
Abstract: While a substantial proportion of adults infected with SARS-CoV-2 progress to develop severe disease, children rarely manifest respiratory complications. Therefore, understanding differences in the local and systemic response to SARS-CoV-2 infection between children and adults may provide important clues about the pathogenesis of SARS-CoV-2 infection. To address this, we first generated a healthy reference multi-omics single cell data set from children (n=30) in whom we have profiled triple matched s les: nasal and tracheal brushings and PBMCs, where we track the developmental changes for 42 airway and 31 blood cell populations from infancy, through childhood to adolescence. This has revealed the presence of naive B and T lymphocytes in neonates and infants with a unique gene expression signature bearing hallmarks of innate immunity. We then contrast the healthy reference with equivalent data from severe paediatric and adult COVID-19 patients (total n=27), from the same three types of s les: upper and lower airways and blood. We found striking differences: children with COVID-19 as opposed to adults had a higher proportion of innate lymphoid and non-clonally expanded naive T cells in peripheral blood, and a limited interferon-response signature. In the airway epithelium, we found the highest viral load in goblet and ciliated cells and describe a novel inflammatory epithelial cell population. These cells represent a transitional regenerative state between secretory and ciliated cells they were found in healthy children and were enriched in paediatric and adult COVID-19 patients. Epithelial cells display an antiviral and neutrophil-recruiting gene signature that is weaker in severe paediatric versus adult COVID-19. Our matched blood and airway s les allowed us to study the spatial dynamics of infection. Lastly, we provide a user-friendly interface for this data 1 as a highly granular reference for the study of immune responses in airways and blood in children.
Publisher: Springer Science and Business Media LLC
Date: 12-12-2010
DOI: 10.1038/NCB2135
Publisher: American Society of Hematology
Date: 30-06-2011
DOI: 10.1182/BLOOD-2010-12-317990
Abstract: The Ets-related gene (ERG) is an Ets-transcription factor required for normal blood stem cell development. ERG expression is down-regulated during early T-lymphopoiesis but maintained in T-acute lymphoblastic leukemia (T-ALL), where it is recognized as an independent risk factor for adverse outcome. However, it is unclear whether ERG is directly involved in the pathogenesis of T-ALL and how its expression is regulated. Here we demonstrate that transgenic expression of ERG causes T-ALL in mice and that its knockdown reduces the proliferation of human MOLT4 T-ALL cells. We further demonstrate that ERG expression in primary human T-ALL cells is mediated by the binding of other T-cell oncogenes SCL/TAL1, LMO2, and LYL1 in concert with ERG, FLI1, and GATA3 to the ERG +85 enhancer. This enhancer is not active in normal T cells but in transgenic mice targets expression to fetal liver c-kit+ cells, adult bone marrow stem rogenitors and early CD4−CD8− double-negative thymic progenitors. Taken together, these data illustrate that ERG promotes T-ALL and that failure to extinguish activity of stem cell enhancers associated with regulatory transcription factors such as ERG can contribute to the development of leukemia.
Publisher: Wiley
Date: 2007
DOI: 10.1002/DVG.20274
Abstract: The Cre/LoxP system provides a powerful tool to investigate gene function in vivo. This system requires Cre-recombinase expressing mouse lines that permit control of gene recombination in a tissue-specific and time-dependent manner. To allow spatio-temporal gene deletion in specific central nervous system (CNS) neuronal populations, we generated mice with a tamoxifen-inducible Cre (Cre-ER(T)) transgene under control of the Scl/Tal1 neural promoter/enhancer -0.9E3 (-0.9E3CreER(T) transgenic mice). Using Cre-reporter mice we have shown that tamoxifen-mediated Cre-ER(T) recombination in -0.9E3CreER(T) mice recapitulated the anticipated expression pattern of Scl in the caudal thalamus, midbrain, hindbrain, and spinal cord. Cre-mediated recombination was also effectively induced during embryogenesis and marked the same population of neurons as observed in the adult. Additionally, we identified a tamoxifen-independent constitutively active -0.9E3CreER(T) mouse line that will be useful for gene deletion during early neurogenesis. These -0.9E3CreER(T) mice will provide tools to investigate the role of neuronal genes in the developing and mature CNS. CNS.
Publisher: American Society of Hematology
Date: 27-08-2009
DOI: 10.1182/BLOOD-2009-02-206573
Abstract: The discovery of JAK2V617F as an acquired mutation in the majority of patients with myeloproliferative disorders (MPDs) and the key role of the JAK2-STAT5 signaling cascade in normal hematopoiesis has focused attention on the downstream transcriptional targets of STAT5. Despite evidence of its vital role in normal erythropoiesis and its ability to recapitulate many of the features of myeloid malignancies, including the MPDs, few functionally validated targets of STAT5 have been described. Here we used a combination of comparative genomics and chromatin immunoprecipitation assays to identify ID1 as a novel target of the JAK2-STAT5 signaling axis in erythroid cells. STAT5 binds and transactivates a downstream enhancer of ID1, and ID1 expression levels correlate with the JAK2V617F mutation in both retrovirally transfected fetal liver cells and polycythemia vera patients. Knockdown and overexpression studies in a well-characterized erythroid differentiation assay from primary murine fetal liver cells demonstrated a survival-promoting action of ID1. This hitherto unrecognized function implicates ID1 in the expansion of erythroblasts during terminal differentiation and suggests that ID1 plays an important role in the pathogenesis of polycythemia vera. Furthermore, our findings contribute to an increasing body of evidence implicating ID proteins in a wider range of cellular functions than initially appreciated.
Publisher: Cold Spring Harbor Laboratory
Date: 26-10-2020
DOI: 10.1101/2020.10.26.353797
Abstract: Changes in gene regulation and expression govern orderly transitions from hematopoietic stem cells to terminally differentiated blood cell types. These transitions are disrupted during leukemic transformation but knowledge of the gene regulatory changes underpinning this process is elusive. We hypothesised that identifying core gene regulatory networks in healthy hematopoietic and leukemic cells could provide insights into network alterations that perturb cell state transitions. A heptad of transcription factors (LYL1, TAL1, LMO2, FLI1, ERG, GATA2, RUNX1) bind key hematopoietic genes in human CD34+ haematopoietic stem and progenitor cells (HSPCs) and have prognostic significance in acute myeloid leukemia (AML). These factors also form a densely interconnected circuit by binding combinatorially at their own, and each other’s, regulatory elements. However, their mutual regulation during normal haematopoiesis and in AML cells, and how perturbation of their expression levels influences cell fate decisions remains unclear. Here, we integrated bulk and single cell data and found that the fully connected heptad circuit identified in healthy HSPCs persists with only minor alterations in AML, and that chromatin accessibility at key heptad regulatory elements was predictive of cell identity in both healthy progenitors and in leukemic cells. The heptad factors GATA2, TAL1 and ERG formed an integrated sub-circuit that regulates stem cell to erythroid transition in both healthy and leukemic cells. Components of this triad could be manipulated to facilitate erythroid transition providing a proof of concept that such regulatory circuits could be harnessed to promote specific cell type transitions and overcome dysregulated haematopoiesis.
Publisher: Springer Science and Business Media LLC
Date: 30-08-2022
DOI: 10.1038/S41467-022-32266-4
Abstract: KMT2A -rearranged infant acute lymphoblastic leukemia (ALL) represents the most refractory type of childhood leukemia. To uncover the molecular heterogeneity of this disease, we perform RNA sequencing, methylation array analysis, whole exome and targeted deep sequencing on 84 infants with KMT2A -rearranged leukemia. Our multi-omics clustering followed by single-s le and single-cell inference of hematopoietic differentiation establishes five robust integrative clusters (ICs) with different master transcription factors, fusion partners and corresponding stages of B-lymphopoietic and early hemato-endothelial development: IRX-type differentiated (IC1), IRX-type undifferentiated (IC2), HOXA-type MLLT1 (IC3), HOXA-type MLLT3 (IC4), and HOXA-type AFF1 (IC5). Importantly, our deep mutational analysis reveals that the number of RAS pathway mutations predicts prognosis and that the most refractory subgroup of IC2 possesses 100% frequency and the heaviest burden of RAS pathway mutations. Our findings highlight the previously under-appreciated intra- and inter-patient heterogeneity of KMT2A -rearranged infant ALL and provide a rationale for the future development of genomics-guided risk stratification and in idualized therapy.
Publisher: Elsevier BV
Date: 09-2012
Publisher: Cold Spring Harbor Laboratory
Date: 09-08-2021
DOI: 10.1101/2021.08.08.455592
Abstract: Mouse hematopoietic stem cells (HSCs) first emerge at embryonic day 10.5 (E10.5) on the ventral surface of the dorsal aorta, by endothelial-to-hematopoietic transition (EHT). We investigated whether cells with mesenchymal stem cell-like activity, which provide an essential niche for long-term HSCs (LT-HSCs) in the bone marrow, reside in the aorta- gonad-mesonephros (AGM) and contribute to the structural development of the dorsal aorta and EHT. Using transgenic mice, we demonstrate a lineage hierarchy for AGM stromal cells and traced the E10.5/E11.5 aortic endothelium and HSCs to mesoderm derived ( Mesp1 ) PDGFRA + stromal cells ( Mesp1 der PSCs). Mesp1 der PSCs dominate the sub-endothelial and ventral stroma in the E10.5–E11.5 AGM but by E13.5 were replaced by neural crest ( Wnt1 ) derived PDGFRA + stromal cells ( Wnt1 der PSCs). Co-aggregating non-hemogenic embryonic and adult endothelial cells with Mesp1 der PSCs but not with Wnt1 der PSCs resulted in activation of a hematopoietic transcriptional program in endothelial cells accompanied by EHT and generation of LT-HSCs. Dose-dependent inhibition of PDGFRA signalling or BMP, WNT, NOTCH signalling interrupted this reprogramming event. This partnership between endothelial cells and AGM Mesp1 der PSCs could potentially be harnessed to manufacture LT-HSCs from endothelium.
Publisher: Elsevier BV
Date: 05-2011
Publisher: Springer Science and Business Media LLC
Date: 11-12-2013
DOI: 10.1038/NCOMMS3924
Publisher: Springer Science and Business Media LLC
Date: 28-07-2022
DOI: 10.1038/S41556-022-00955-3
Abstract: Mouse haematopoietic stem cells (HSCs) first emerge at embryonic day 10.5 (E10.5), on the ventral surface of the dorsal aorta, by endothelial-to-haematopoietic transition. We investigated whether mesenchymal stem cells, which provide an essential niche for long-term HSCs (LT-HSCs) in the bone marrow, reside in the aorta–gonad–mesonephros and contribute to the development of the dorsal aorta and endothelial-to-haematopoietic transition. Here we show that mesoderm-derived PDGFRA + stromal cells ( Mesp1 der PSCs) contribute to the haemogenic endothelium of the dorsal aorta and populate the E10.5–E11.5 aorta–gonad–mesonephros but by E13.5 were replaced by neural-crest-derived PSCs ( Wnt1 der PSCs). Co-aggregating non-haemogenic endothelial cells with Mesp1 der PSCs but not Wnt1 der PSCs resulted in activation of a haematopoietic transcriptional programme in endothelial cells and generation of LT-HSCs. Dose-dependent inhibition of PDGFRA or BMP, WNT and NOTCH signalling interrupted this reprogramming event. Together, aorta–gonad–mesonephros Mesp1 der PSCs could potentially be harnessed to manufacture LT-HSCs from endothelium.
Publisher: American Society of Hematology
Date: 03-10-2013
DOI: 10.1182/BLOOD-2013-03-490425
Abstract: Genome-wide binding profiles of FLI1, ERG, GATA2, RUNX1, SCL, LMO2, and LYL1 in human HSPCs reveals patterns of combinatorial TF binding. Integrative analysis of transcription factor binding reveals a densely interconnected network of coding and noncoding genes in human HSPCs.
Publisher: Elsevier BV
Date: 07-2012
Publisher: Informa UK Limited
Date: 10-2007
DOI: 10.1128/MCB.00931-07
Publisher: American Society of Hematology
Date: 21-03-2013
DOI: 10.1182/BLOOD-2012-07-446120
Abstract: The ERG stem cell enhancer is active in acute myeloid leukemia and is regulated by a heptad of transcription factors. Expression signatures derived from ERG promoter–enhancer activity and heptad expression are associated with clinical outcome.
Publisher: Springer Science and Business Media LLC
Date: 22-12-2021
DOI: 10.1038/S41586-021-04345-X
Abstract: It is not fully understood why COVID-19 is typically milder in children 1–3 . Here, to examine the differences between children and adults in their response to SARS-CoV-2 infection, we analysed paediatric and adult patients with COVID-19 as well as healthy control in iduals (total n = 93) using single-cell multi-omic profiling of matched nasal, tracheal, bronchial and blood s les. In the airways of healthy paediatric in iduals, we observed cells that were already in an interferon-activated state, which after SARS-CoV-2 infection was further induced especially in airway immune cells. We postulate that higher paediatric innate interferon responses restrict viral replication and disease progression. The systemic response in children was characterized by increases in naive lymphocytes and a depletion of natural killer cells, whereas, in adults, cytotoxic T cells and interferon-stimulated subpopulations were significantly increased. We provide evidence that dendritic cells initiate interferon signalling in early infection, and identify epithelial cell states associated with COVID-19 and age. Our matching nasal and blood data show a strong interferon response in the airways with the induction of systemic interferon-stimulated populations, which were substantially reduced in paediatric patients. Together, we provide several mechanisms that explain the milder clinical syndrome observed in children.
Publisher: American Society of Hematology
Date: 12-12-2019
Abstract: Cohesin mutations are common in myeloid malignancy. Sasca et al elucidate the potential role of cohesin loss in myelodysplastic syndrome and acute myeloid leukemia (MDS/AML). They demonstrate that cohesin binding is critical for erythroid-specific gene expression and that reduction in cohesin impairs terminal erythroid maturation and promotes myeloid malignancy.
Publisher: Springer Science and Business Media LLC
Date: 02-2011
DOI: 10.1186/SCRT47
Publisher: Springer Science and Business Media LLC
Date: 16-07-2018
Publisher: Springer Science and Business Media LLC
Date: 02-08-2010
DOI: 10.1038/ONC.2010.320
Abstract: The T-cell oncogene Lim-only 2 (LMO2) critically influences both normal and malignant haematopoiesis. LMO2 is not normally expressed in T cells, yet ectopic expression is seen in the majority of T-acute lymphoblastic leukaemia (T-ALL) patients with specific translocations involving LMO2 in only a subset of these patients. Ectopic lmo2 expression in thymocytes of transgenic mice causes T-ALL, and retroviral vector integration into the LMO2 locus was implicated in the development of clonal T-cell disease in patients undergoing gene therapy. Using array-based chromatin immunoprecipitation, we now demonstrate that in contrast to B-acute lymphoblastic leukaemia, human T-ALL s les largely use promoter elements with little influence from distal enhancers. Active LMO2 promoter elements in T-ALL included a previously unrecognized third promoter, which we demonstrate to be active in cell lines, primary T-ALL patients and transgenic mice. The ETS factors ERG and FLI1 previously implicated in lmo2-dependent mouse models of T-ALL bind to the novel LMO2 promoter in human T-ALL s les, while in return LMO2 binds to blood stem rogenitor enhancers in the FLI1 and ERG gene loci. Moreover, LMO2, ERG and FLI1 all regulate the +1 enhancer of HHEX/PRH, which was recently implicated as a key mediator of early progenitor expansion in LMO2-driven T-ALL. Our data therefore suggest that a self-sustaining triad of LMO2/ERG/FLI1 stabilizes the expression of important mediators of the leukaemic phenotype such as HHEX/PRH.
Publisher: Springer Science and Business Media LLC
Date: 17-01-2023
DOI: 10.1038/S41467-023-35910-9
Abstract: Developmental control of gene expression critically depends on distal cis-regulatory elements including enhancers which interact with promoters to activate gene expression. To date no global experiments have been conducted that identify their cell type and cell stage-specific activity within one developmental pathway and in a chromatin context. Here, we describe a high-throughput method that identifies thousands of differentially active cis-elements able to stimulate a minimal promoter at five stages of hematopoietic progenitor development from embryonic stem (ES) cells, which can be adapted to any ES cell derived cell type. We show that blood cell-specific gene expression is controlled by the concerted action of thousands of differentiation stage-specific sets of cis-elements which respond to cytokine signals terminating at signalling responsive transcription factors. Our work provides an important resource for studies of hematopoietic specification and highlights the mechanisms of how and where extrinsic signals program a cell type-specific chromatin landscape driving hematopoietic differentiation.
Publisher: Springer Science and Business Media LLC
Date: 07-10-2013
DOI: 10.1038/LEU.2013.287
Publisher: Ferrata Storti Foundation (Haematologica)
Date: 24-01-2019
Publisher: Elsevier BV
Date: 03-2003
DOI: 10.1016/S0888-7543(03)00005-3
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.
Publisher: Cold Spring Harbor Laboratory
Date: 18-04-2023
DOI: 10.1101/2023.04.18.537282
Abstract: Hematopoietic stem and progenitor cells (HSPCs) rely on a complex interplay of transcription factors (TFs) to regulate differentiation into mature blood cells. A heptad of TFs - FLI1, ERG, GATA2, RUNX1, TAL1, LYL1, LMO2 - bind regulatory elements in bulk CD34+ HSPCs. However, whether specific heptad-TF combinations have distinct roles in regulating hematopoietic differentiation remained unknown. We mapped genome-wide chromatin contacts and TF binding profiles in HSPC subsets (HSC, CMP, GMP, MEP) and found that heptad occupancy and enhancer-promoter interactions varied significantly across cell types and were associated with cell-type-specific gene expression. Distinct regulatory elements were enriched with specific heptad-TF combinations, including stem-cell-specific elements with ERG, and myeloid- and erythroid-specific elements with combinations of FLI1, RUNX1, GATA2, TAL1, LYL1, and LMO2. These findings suggest that specific heptad-TF combinations play critical roles in regulating hematopoietic differentiation and provide a valuable resource for development of targeted therapies to manipulate specific HSPC subsets.
Publisher: Springer Science and Business Media LLC
Date: 20-04-2021
DOI: 10.1038/S41591-021-01329-2
Abstract: Analysis of human blood immune cells provides insights into the coordinated response to viral infections such as severe acute respiratory syndrome coronavirus 2, which causes coronavirus disease 2019 (COVID-19). We performed single-cell transcriptome, surface proteome and T and B lymphocyte antigen receptor analyses of over 780,000 peripheral blood mononuclear cells from a cross-sectional cohort of 130 patients with varying severities of COVID-19. We identified expansion of nonclassical monocytes expressing complement transcripts ( CD16 + C1QA/B/C + ) that sequester platelets and were predicted to replenish the alveolar macrophage pool in COVID-19. Early, uncommitted CD34 + hematopoietic stem rogenitor cells were primed toward megakaryopoiesis, accompanied by expanded megakaryocyte-committed progenitors and increased platelet activation. Clonally expanded CD8 + T cells and an increased ratio of CD8 + effector T cells to effector memory T cells characterized severe disease, while circulating follicular helper T cells accompanied mild disease. We observed a relative loss of IgA2 in symptomatic disease despite an overall expansion of plasmablasts and plasma cells. Our study highlights the coordinated immune response that contributes to COVID-19 pathogenesis and reveals discrete cellular components that can be targeted for therapy.
Publisher: Springer Science and Business Media LLC
Date: 29-09-2021
Publisher: American Society of Hematology
Date: 26-10-2023
Abstract: Hematopoietic stem and progenitor cells (HSPCs) rely on a complex interplay of transcription factors (TFs) to regulate differentiation into mature blood cells. A heptad of TFs - FLI1, ERG, GATA2, RUNX1, TAL1, LYL1, LMO2 - bind regulatory elements in bulk CD34+ HSPCs. However, whether specific heptad-TF combinations have distinct roles in regulating hematopoietic differentiation remained unknown. We mapped genome-wide chromatin contacts (HiC, H3K27ac HiChIP), chromatin modifications (H3K4me3, H3K27ac, H3K27me3) and 10 TF binding profiles (the Heptad, PU.1, CTCF, and STAG2) in HSPC subsets (HSC-MPP, CMP, GMP, MEP) and found that TF occupancy and enhancer-promoter interactions varied significantly across cell types and were associated with cell-type-specific gene expression. Distinct regulatory elements were enriched with specific heptad-TF combinations, including stem-cell-specific elements with ERG, and myeloid- and erythroid-specific elements with combinations of FLI1, RUNX1, GATA2, TAL1, LYL1, and LMO2. Furthermore, heptad-occupied regions in HSPCs were subsequently bound by lineage-defining TFs such as PU.1 and GATA1, suggesting that heptad factors may prime regulatory elements for use in mature cell types. We also found that enhancers with cell-type-specific heptad occupancy shared a common grammar with respect to TF binding motifs, suggesting that combinatorial binding of specific TF complexes was at least partially regulated by features encoded in specific DNA sequence motifs. Taken together, this study provides a comprehensive characterisation of the gene regulatory landscape in rare subpopulations of human HSPCs. The accompanying datasets should serve as a valuable resource for understanding adult hematopoiesis and a framework for analysing aberrant regulatory networks in leukemic cells.
Publisher: American Society of Hematology
Date: 21-10-2010
DOI: 10.1182/BLOOD-2010-05-284968
Abstract: Glucocorticoids play a critical role in the therapy of lymphoid malignancies, including pediatric acute lymphoblastic leukemia (ALL), although the mechanisms underlying cellular resistance remain unclear. We report glucocorticoid resistance attributable to epigenetic silencing of the BIM gene in pediatric ALL biopsies and xenografts established in immune-deficient mice from direct patient explants as well as a therapeutic approach to reverse resistance in vivo. Glucocorticoid resistance in ALL xenografts was consistently associated with failure to up-regulate BIM expression after dexamethasone exposure despite confirmation of a functional glucocorticoid receptor. Although a comprehensive assessment of BIM CpG island methylation revealed no consistent changes, glucocorticoid resistance in xenografts and patient biopsies significantly correlated with decreased histone H3 acetylation. Moreover, the histone deacetylase inhibitor vorinostat relieved BIM repression and exerted synergistic antileukemic efficacy with dexamethasone in vitro and in vivo. These findings provide a novel therapeutic strategy to reverse glucocorticoid resistance and improve outcome for high-risk pediatric ALL.
Publisher: The Company of Biologists
Date: 15-07-2015
DOI: 10.1242/BIO.011494
Abstract: During embryonic development, hematopoietic cells develop by a process of endothelial-to hematopoietic transition of a specialized population of endothelial cells. These hemogenic endothelium (HE) cells in turn develop from a primitive population of FLK1+ mesodermal cells. Endoglin (ENG) is an accessory TGF-β receptor that is enriched on the surface of endothelial and hematopoietic stem cells and is also required for the normal development of hemogenic precursors. However, the functional role of ENG during the transition of FLK1+ mesoderm to hematopoietic cells is ill defined. To address this we used a murine embryonic stem cell model that has been shown to mirror the temporal emergence of these cells in the embryo. We noted that FLK1+ mesodermal cells expressing ENG generated fewer blast colony-forming cells but had increased hemogenic potential when compared with ENG non-expressing cells. TIE2+/CD117+ HE cells expressing ENG also showed increased hemogenic potential compared with non-expressing cells. To evaluate whether high ENG expression accelerates hematopoiesis, we generated an inducible ENG expressing ES cell line and forced expression in FLK1+ mesodermal or TIE2+/CD117+ HE cells. High ENG expression at both stages accelerated the emergence of CD45+ definitive hematopoietic cells. High ENG expression was associated with increased pSMAD2/eNOS expression and NO synthesis in hemogenic precursors. Inhibition of eNOS blunted the ENG induced increase in definitive hematopoiesis. Taken together, these data show that ENG potentiates the emergence of definitive hematopoietic cells by modulating TGF-β SMAD2 signalling and increasing eNOS/NO synthesis.
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Berthold Gottgens.