A faithful in vivo model of human MLL-AF4 proB acute lymphoblastic leukemia
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE76978 | GEO | 2016/11/23
SECONDARY ACCESSION(S): PRJNA309171
REPOSITORIES: GEO
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Project description:The t(4;11)(q21;q23) fuses MLL to AF4, the most common MLL fusion partner. Here we show that MLL fused to murine Af4, highly conserved with human AF4, produces high-titer retrovirus permitting efficient transduction of human CD34+ cells to generate a faithful model of t(4;11) proB ALL that fully recapitulates the immunophenotypic and molecular aspects of the disease. MLL-Af4 induces a distinct B-ALL from MLL-AF9 through differential DNA binding of the fusion proteins leading to specific gene expression patterns. MLL-Af4 cells can assume a myeloid state under environmental pressure but retain lymphoid-lineage potential. We observed this incongruity in t(4;11) patients who evaded CD19-directed therapy by undergoing myeloid-lineage switch. Our model provides a valuable tool to unravel the pathogenesis of MLL-AF4 leukemogenesis.
2016-11-23 | GSE84116 | GEO
Project description:In MLL-rearranged (MLLr) leukemias the N terminal part of the MLL gene can be fused to over 60 different partner genes. Here, we investigate the genome wide binding of the MLL-AF9 and MLL-AF4 fusion proteins and their epigenetic signatures in order to define a core set of MLLr targets. We uncover both common as well as specific MLL-AF9 and MLL-AF4 target genes, which are all marked by H3K79me2, H3K27ac, and H3K4me3. Apart from promoter binding, we also identify MLL-AF9 and MLL-AF4 binding at specific subsets of non overlapping active distal regulatory elements. Despite this differential enhancer binding MLL-AF9 and MLL-AF4 still share a common gene program, which represents part of the RUNX1 gene program and constitutes of CD34+ and monocyte specific genes. Comparing these datasets revealed several zinc finger transcription factors as potential MLL-AF9 co-regulators. Together these results suggest that MLL-fusions collaborate with specific subsets of TFs to aberrantly regulate the RUNX1 gene program in 11q23 AMLs.
2017-01-24 | GSE79899 | GEO
Project description:MLL-fusions represent a large group of leukemia drivers, whose diversity originates from the vast molecular heterogeneity of C-terminal fusion partners of MLL protein. While studies of selected MLL-fusions have revealed critical molecular pathways, unifying mechanisms across all MLL-fusions remain poorly understood. We present the first comprehensive survey of protein-protein interactions of seven distantly related MLL-fusion proteins: MLL-AF1p, MLL-AF4, MLL-AF9, MLL-CBP, MLL-EEN, MLL-ENL and MLL-GAS7.
2018-05-25 | PXD009338 | Pride
Project description:MLL/AF4 fusion transcript knock-down time course in the MLL/AF4-positive B-cell precursor ALL cell line SEM using MLL/AF4 fusion site-specific siRNAs (siMLL/AF4). The aim was to identify genes responsive to MLL/AF4 expression modulation.
2018-07-21 | GSE71140 | GEO
Project description:Fusion of the N-terminus of the mixed-lineage-leukemia (MLL) gene with various partner genes drives acute lymphoblastic leukemia (ALL). Despite the fusion proteins sharing some common attributes, transcriptome heterogeneity of MLL-fusion ALL is observed and the underlying mechanism and biological consequences are unknown. We compared the genome-wide occupancy of MLL-Af4 and MLL-AF9 in human ALL cells expressing FLAG-tagged fusion proteins. Although both oncoproteins retain the same MLL N-terminal domains that mediate chromatin binding, the two fusion proteins displayed largely non-overlapping binding profiles, with MLL-AF9 showing preferential binding at repetitive elements. The binding specificity of each fusion protein was associated with differential global gene activation distinguishing the two ALLs. A subset of prednisolone response genes were among the differentially regulated targets, and the resistance related genes were specifically upregulated in MLL-Af4/AF4 cells. These studies provide evidence that distinct chromatin occupancy of different MLL-fusion proteins is one driving force for transcriptome heterogeneity of MLL-fusion ALL, which could potentially result in the disparate therapeutic outcome of the disease.
2018-04-30 | GSE103947 | GEO
Project description:Aberrant enhancer activation is a key mechanism driving oncogene expression in many cancers. While much is known about the regulation of larger chromosome domains in eukaryotes, the details of enhancer-promoter interactions remain poorly understood. Recent work suggests co-activators like BRD4 and Mediator have little impact on enhancer-promoter interactions. In leukemias controlled by the MLL-AF4 fusion protein, we use the ultra-high resolution technique Micro-Capture-C (MCC) to show that MLL-AF4 binding promotes broad, high-density regions of enhancer-promoter interactions at a subset of key targets. These enhancers are enriched for transcription elongation factors like PAF1C and FACT and loss of these factors abolishes enhancer-promoter contact. This work not only provides a new model for how MLL-AF4 is able to drive high levels of transcription at key genes in leukemia, but also suggests a more general model linking enhancer-promoter crosstalk and transcription elongation.
2023-08-18 | PXD043920 | Pride
Project description:The MLL-AF4 fusion gene is a hallmark genomic aberration in high-risk acute lymphoblastic leukemia in infants. Although it is well-established that MLL-AF4 arises pre-natally during human development, its effects on hematopoietic development in utero remains unexplored. We have created a human-specific in vitro system to study early hemato-endothelial development in MLL-AF4-expressing human embryonic stem cells (hESCs). Differentiation and functional studies as well as clonal analyses and gene expression profiling reveal that expression of MLL-AF4 in hESCs has a phenotypic, functional and gene expression impact. It enhances the specification of hemogenic precursors from hESCs and impairs further hematopoietic commitment of these precursors in favour of the endothelial cell fate. Similar to that reported in cord blood CD34+ hematopoietic stem/progenitor cells (HSPCs), MLL-AF4 expression is not sufficient to transform hESC-derived hematopoietic cells in vitro or in vivo, indicating that additional events may be required to initiate leukemogenesis or that embryonic hematopoiesis is not the appropriate human cellular target for MLL-AF4-mediated leukemogenesis. This work illustrates how hESCs can provide unique insights into human development and further our understanding of how leukemic fusion genes known to arise pre-natally regulate human embryonic hematopoietic specification. MLL is involved in transcriptional regulation and most MLL translocations appear to result in increased expression of Hox genes and hematopoietic genes. We therefore assessed the impact of MLL-AF4 expression on the transcriptome of hESCs. Gene expression profiling performed in MLL-AF4 hESCs revealed that MLL-AF4 preferentially activates transcription. 1826 out of the 3001 genes (61%) expressed were up-regulated in MLL-AF4 hESCs. Human ESC samples were collected during the exponential cell growth phase and stabilized in RNA later. 500 ng of each total RNA sample was labelled with Cy3 using the Quick-Amp Labelling kit and hybridized with the Gene Expression Hybridization kit to a Whole Human Genome Oligo Microarray (Agilent Technologies) following the Manufacturer’s instructions. Each cell line was analyzed as independent duplicates. NEO-expressing (empty lentivector) hESC line was used as the baseline.
2011-06-09 | E-GEOD-29869 | biostudies-arrayexpress
Project description:Malignant transformation in a multipotential precursor has recently been shown to underlie mixed phenotype acute leukaemias. In contrast, and despite the conclusive demonstration that MLL-AF4 infant ALL arises in utero. In order to address this we purified haematopoietic stem/progenitor cell (HSPC) populations from four non-lineage switching presentation infant ALL cases and one ALL presentation which went on to lineage switch at relapse. The specific MLL-AF4 fusion event was determined in unsorted samples by LDI-PCR and identified in purified populations by nested PCR. In three cases where non-lineage restricted populations were able to be purified, MLL-AF4 was identified in the CD34+CD38-CD45RA+ population (LK228, LK230, LS01), the CD34+CD38-CD45RA-CD90- multipotential progenitor population (MPP, LS01) and even a candidate CD34+CD38-CD45RA-CD90+ haematopoietic stem cell (HSC) population (LK228) Interestingly, in a single non-switched MLL-AF9 case analysed for external comparison, the fusion was only identified in CD19+ blast/B cell populations, not in any HSPC population. Unexpectedly, we were also able to identify the presence of the MLL-AF4 fusion in apparently normally differentiated CD34-CD19/3-HLA-DR+CD14/11c+ monocytes/dendritic cells from the peripheral blood/bone marrow of 4/5 cases examined. This finding was further supported by single cell analysis of LS01PALL which identified the fusion in 2/22 CD34-CD19/3-HLA-DR+CD14/11c+ monocytes/dendritic cells analysed. Furthermore, the matched AML sample (LS01RAML) also contained MLL-AF4 positive mature T lymphoid cells. These data imply that MLL-AF4 does not impose a complete block on normal haematopoietic differentiation, and raise the question of what additional factors contribute to leukaemic lineage determination in the setting of the MLL-AF4 translocation. To examine the functional capacity of MLL-AF4 transformed precursor cells we generated a patient-derived xenograft model using NOD-scid/IL2Rγ-/- (NSG) mice. Serial xenotransplantation identified an MLL-AF4 positive clone persisting within the human CD34+CD38-CD45RA-CD90+ compartment across four generations of mice, confirming self-renewal of this population. Together these data identify an early multipotent progenitor or HSC as the putative cell of origin for MLL-AF4 ALL. Furthermore, they demonstrate that MLL-AF4, uniquely amongst MLL fusion genes, imposes a profound lymphoid bias on the developing leukemia but without completely abolishing broader, non-malignant, haematopoietic differentiation.
2020-04-21 | GSE132396 | GEO
Project description:Malignant transformation in a multipotential precursor has recently been shown to underlie mixed phenotype acute leukaemias. In contrast, and despite the conclusive demonstration that MLL-AF4 infant ALL arises in utero. In order to address this we purified haematopoietic stem/progenitor cell (HSPC) populations from four non-lineage switching presentation infant ALL cases and one ALL presentation which went on to lineage switch at relapse. The specific MLL-AF4 fusion event was determined in unsorted samples by LDI-PCR and identified in purified populations by nested PCR. In three cases where non-lineage restricted populations were able to be purified, MLL-AF4 was identified in the CD34+CD38-CD45RA+ population (LK228, LK230, LS01), the CD34+CD38-CD45RA-CD90- multipotential progenitor population (MPP, LS01) and even a candidate CD34+CD38-CD45RA-CD90+ haematopoietic stem cell (HSC) population (LK228) Interestingly, in a single non-switched MLL-AF9 case analysed for external comparison, the fusion was only identified in CD19+ blast/B cell populations, not in any HSPC population. Unexpectedly, we were also able to identify the presence of the MLL-AF4 fusion in apparently normally differentiated CD34-CD19/3-HLA-DR+CD14/11c+ monocytes/dendritic cells from the peripheral blood/bone marrow of 4/5 cases examined. This finding was further supported by single cell analysis of LS01PALL which identified the fusion in 2/22 CD34-CD19/3-HLA-DR+CD14/11c+ monocytes/dendritic cells analysed. Furthermore, the matched AML sample (LS01RAML) also contained MLL-AF4 positive mature T lymphoid cells. These data imply that MLL-AF4 does not impose a complete block on normal haematopoietic differentiation, and raise the question of what additional factors contribute to leukaemic lineage determination in the setting of the MLL-AF4 translocation. To examine the functional capacity of MLL-AF4 transformed precursor cells we generated a patient-derived xenograft model using NOD-scid/IL2Rγ-/- (NSG) mice. Serial xenotransplantation identified an MLL-AF4 positive clone persisting within the human CD34+CD38-CD45RA-CD90+ compartment across four generations of mice, confirming self-renewal of this population. Together these data identify an early multipotent progenitor or HSC as the putative cell of origin for MLL-AF4 ALL. Furthermore, they demonstrate that MLL-AF4, uniquely amongst MLL fusion genes, imposes a profound lymphoid bias on the developing leukemia but without completely abolishing broader, non-malignant, haematopoietic differentiation.
2020-04-21 | GSE130142 | GEO
Project description:We created a mouse model where conditional expression of physiologic levels of an Mll-AF4 fusion oncogene induces development of acute lymphoblastic (ALL) or acute myeloid leukemias (AML). ChIP-chip analysis demonstrated increased histone H3 Lysine 79 (H3K79) dimethylation that correlated with Mll-AF4 associated gene expression profiles in murine ALLs, and in human MLL-rearranged leukemias. In addition, human MLL-rearranged ALLs can be distinguished from other ALLs by their genome-wide H3K79 methylation profiles. Keywords: Cell type comparison
2008-11-04 | GSE12362 | GEO