Changes in chromatin accessibility over time in cells expressing t(4;11) fusion proteins [I]
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE178567 | GEO | 2021/06/22
REPOSITORIES: GEO
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Project description:We have used a constitutive MLL-AF4 fusion gene together with a inducible AF4-MLL fusion gene to investigate the power of theses fusion proteins. All transgenes were stably or transiently transfected.
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Project description:We have used a combination of constitutive and inducible MLL-AF4 and AF4-MLL fusion genes to investigate the power of theses fusion proteins. All transgenes were stably or transiently transfected. Here, we compared 48 induction of MLL-AF4 or AF4-MLL (day 3) and looked for persistance at days 28. This was compared to the situation with constitutive MLL-AF4 with 48 inductionn of AF4-MLL at day 3 and day 28.
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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.
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2018-05-25 | PXD009338 | Pride
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:The Mixed Lineage Leukemia 1 protein (MLL1) is an important epigenetic regulator required for the maintenance of gene activation during development. MLL1 chromosome translocations produce novel fusion proteins that cause aggressive leukemias in humans. Individual MLL1 fusion proteins have distinct leukemic phenotypes even when expressed in the same cell type, but how this distinction is delineated on a molecular level is poorly understood. Here we highlight a unique molecular mechanism whereby MLL-AF4 specifically activates the RUNX1 gene and the RUNX1 protein interacts with the product of the reciprocal AF4-MLL translocation. These results support a mechanism of leukemic growth whereby two oncogenic fusion proteins cooperate by activating a target gene and then interacting directly with its downstream product ChIP-seq using RUNX1 antibody in SEM cells
2013-01-31 | E-GEOD-42075 | biostudies-arrayexpress
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:The Mixed Lineage Leukemia 1 protein (MLL1) is an important epigenetic regulator required for the maintenance of gene activation during development. MLL1 chromosome translocations produce novel fusion proteins that cause aggressive leukemias in humans. Individual MLL1 fusion proteins have distinct leukemic phenotypes even when expressed in the same cell type, but how this distinction is delineated on a molecular level is poorly understood. Here we highlight a unique molecular mechanism whereby MLL-AF4 specifically activates the RUNX1 gene and the RUNX1 protein interacts with the product of the reciprocal AF4-MLL translocation. These results support a mechanism of leukemic growth whereby two oncogenic fusion proteins cooperate by activating a target gene and then interacting directly with its downstream product
2013-01-31 | GSE42075 | GEO
Project description:MLL-AF4 is a hallmark genomic aberration which arises prenatally in high-risk infant acute lymphoblastic leukemia (ALL). In human embryonic stem cells (hESCs), MLL-AF4 skewed hemato-endothelial specification but was not sufficient for transformation. Additional cooperating genetic insults seem required for MLL-AF4-mediated leukemogenesis. FLT3 is highly expressed in MLL-AF4+ ALL through activating mutations (FLT3-TKD or FLT3-ITD) or increased transcriptional expression, being therefore considered a potential cooperating event in MLL-AF4+ ALL. Here, we explored the developmental impact of FLT3 activation on its own or in cooperation with MLL-AF4 in the hematopoietic fate of hESCs. FLT3 activation did not impact specification of CD45-CD31+ hemogenic precursors but significantly enhanced the formation of CD45+CD34+ and CD45+ blood cells and blood progenitors with clonogenic potential. Importantly, FLT3 activation through FLT3 mutations or FLT3-WT overexpression completely abrogated hematopoietic differentiation from MLL-AF4-expressing hESCs, indicating that FLT3 activation cooperates with MLL-AF4 to inhibit human embryonic hematopoiesis. Cell cycle/apoptosis analyses suggest that FLT3 activation directly impacts hESC specification rather than selective proliferation/survival of hESC-emerging hematopoietic derivatives. Transcriptional profiling supported the limited impact of FLT3 activation on hESC specification towards CD45-hemogenic precursors and the enhanced hematopoiesis upon FLT3 activation, and inhibited hematopoiesis upon MLL-AF4 expression in FLT3-activated hESCs which was associated to large transcriptional changes and regulation of master early hematopoietic genes. Also, although FLT3 activation and MLL-AF4 cooperate to inhibit embryonic hematopoiesis the underlying molecular/genetic mechanisms differ depending on how FLT3 activation is achieved. Finally, FLT3 activation did not cooperate with MLL-AF4 to immortalize/transform hESC-derived hematopoietic cells. 18 samples were analyzed. CD45- hemogenic precursors EV, 2 biological rep CD45- hemogenic precursors FLT3-TKD, 2 biological rep CD45- hemogenic precursors FLT3-WT, 2 biological rep CD45- hemogenic precursors FLT3-TKD/MLLAF4, 2 biological rep CD45- hemogenic precursors FLT3-WT/MLLAF4, 2 biological rep CD45+ blood cells EV, 1 biological rep CD45+ blood cells FLT3-TKD, 2 biological rep CD45+ blood cells FLT3-WT, 2 biological rep CD45+ blood cells FLT3-TKD/MLLAF4, 2 biological rep CD45+ blood cells FLT3-WT/MLLAF4, 1 biological rep
2013-06-04 | E-GEOD-40103 | biostudies-arrayexpress
Project description:MLL-AF4 is a hallmark genomic aberration which arises prenatally in high-risk infant acute lymphoblastic leukemia (ALL). In human embryonic stem cells (hESCs), MLL-AF4 skewed hemato-endothelial specification but was not sufficient for transformation. Additional cooperating genetic insults seem required for MLL-AF4-mediated leukemogenesis. FLT3 is highly expressed in MLL-AF4+ ALL through activating mutations (FLT3-TKD or FLT3-ITD) or increased transcriptional expression, being therefore considered a potential cooperating event in MLL-AF4+ ALL. Here, we explored the developmental impact of FLT3 activation on its own or in cooperation with MLL-AF4 in the hematopoietic fate of hESCs. FLT3 activation did not impact specification of CD45-CD31+ hemogenic precursors but significantly enhanced the formation of CD45+CD34+ and CD45+ blood cells and blood progenitors with clonogenic potential. Importantly, FLT3 activation through FLT3 mutations or FLT3-WT overexpression completely abrogated hematopoietic differentiation from MLL-AF4-expressing hESCs, indicating that FLT3 activation cooperates with MLL-AF4 to inhibit human embryonic hematopoiesis. Cell cycle/apoptosis analyses suggest that FLT3 activation directly impacts hESC specification rather than selective proliferation/survival of hESC-emerging hematopoietic derivatives. Transcriptional profiling supported the limited impact of FLT3 activation on hESC specification towards CD45-hemogenic precursors and the enhanced hematopoiesis upon FLT3 activation, and inhibited hematopoiesis upon MLL-AF4 expression in FLT3-activated hESCs which was associated to large transcriptional changes and regulation of master early hematopoietic genes. Also, although FLT3 activation and MLL-AF4 cooperate to inhibit embryonic hematopoiesis the underlying molecular/genetic mechanisms differ depending on how FLT3 activation is achieved. Finally, FLT3 activation did not cooperate with MLL-AF4 to immortalize/transform hESC-derived hematopoietic cells.
2013-06-04 | GSE40103 | GEO