Project description:These data were generated to investigate the impact on the gene expression of the chimeric transcription factor CBFA2T3-GLIS2 (a.k.a ETO2-GLIS2 and abbreviated here as EG) which is associated with pediatric leukemia (LAM7), to assess the functional roles of several domains of this protein (the ETO2 and GLIS2 moiety) on the gene dysregulation induced by EG through the generation of several mutants (deleted for the NHR2 domain of ETO2: dNHR2 or with a C265G mutation in the GLIS2 moiety: C265G). The different EG forms were cloned into a doxycycline-inducible lentiviral vector and transcriptomes were performed 24 hours post doxycycline induction.
Project description:Acute megakaryoblastic leukemia (AMKL) is a subtype of leukemia primarily diagnosed in childhood and generally associated with poor prognosis. Genetic alterations found in de novo childhood AMKL include the OTT-MAL fusion, MLL and NUP98 fusions and the recently identified ETO2-GLIS2 fusion that involves two transcriptional regulators. In order to identify ETO2-GLIS2 target genes, we performed two approaches: 1-Ectopic expression of ETO2-GLIS2, ETO2, GLIS2 and OTT-MAL in HEL cells, which does not endogenously express AMKL fusion oncogenes. Transduced cells marked by expression of the GFP were sorted by flow cytometry 24 hours after transduction and RNA was extracted with the Qiagen Rneasy kit including DNase treatment. 2-Expression of a small peptide (NC128), which interferes with the dimerization and cofactor recruitment by the ETO2-GLIS2 fusion, within MO7E cells derived from an AMKL patient and expressing endogenously the ETO2-GLIS2 fusion. Transduced cells marked by expression of the GFP were sorted by flow cytometry 7 days after transduction and RNA was extracted with the Qiagen Rneasy kit including DNase treatment. After quantification of biological replicates, and quality control (Bioanalyser, Agilent), RNA were hybridized on Agilent arrays as indicated below.
Project description:Acute megakaryoblastic leukemia (AMKL) is a subtype of leukemia primarily diagnosed in childhood and generally associated with poor prognosis. Genetic alterations found in de novo childhood AMKL include the OTT-MAL fusion, MLL and NUP98 fusions and the recently identified ETO2-GLIS2 fusion that involves two transcriptional regulators. In order to identify ETO2-GLIS2-bound regions as well as the chromatin landscape in human AMKL cells, we performed ChIP-seq analyses in AMKL MO7E cell line and in AMKL patient derived cells. Since existing GLIS2 antibodies could not successfully pull-down ETO2-GLIS2, we introduced the GFP at the endogenous GLIS2 loci in the MO7E cell line using a CRISPR/Cas9 approach to obtain physiological expression of a GFP-tagged ETO2-GLIS2 (MO7e-KI cell line). ChIP-seq were performed using antibody against GFP and ETO2 to identify ETO2-GLIS2-bound regions, against ERG to investigate colocalization and against chromatin marks to highlight repressed (H3K27me3) and active (H3K4me3: promoters; H3K27Ac, H3K4me1: enhancers) regions.
Project description:To characterize the molecular consequences of ETO2-GLIS2 expression in iPSC-derived cells, we performed a transcriptome analysis on control and two ETO2-GLIS2 clones at day18 of differentiation. From the control, the CD41+CD42- and CD41+CD42+ populations were sorted to obtain normal immature progenitors and maturing megakaryocytes. From ETO2-GLIS2-expressing cells, CD41+CD42+ and the aberrant CD41lowCD42low were analyzed.Whole transcriptome sequencing (WTS) was performed using Illumina Nextseq500 platform. cDNA libraries were synthesized from 250 ng total RNA using the TruSeq Stranded mRNA kit (Illumina) following manufacturers’ instructions. Briefly, poly-A containing mRNA molecules were reverse transcribed to double stranded cDNA fragments that were then adenylated at 3' ends and ligated to single-index adapters. PCR-enriched libraries were then quantified by Quant-It picogreen assay (Thermo-Fisher) and sized with the High Sensitivity kit on the 2100 Bioanalyzer (Agilent Technologies). Sequencing was performed at 2x80bp using Illumina Sequencing by synthesis (SBS) technology.
Project description:Several fusion oncogenes showing a higher incidence in pediatric acute myeloid leukemia are associated with heterogeneous megakaryoblastic and other myeloid features. Here we addressed how developmental mechanisms influence human leukemogenesis by ETO2::GLIS2, a hallmark of dismal prognosis. We induced expression of ETO2::GLIS2 in primary human fetal and cord blood CD34+ hematopoietic cells and obtained bulk transcriptomes after in vitro cultures or in vivo engraftment and leukemia development in immunodeficient recipients (NSG or NSG-SGM3=NSG-S).
Project description:The ETO-family transcriptional corepressors, including ETO, ETO2 and MTGR1, are all involved in leukemia-causing chromosomal translocations. In every case, an ETO-family corepressor acquires a DNA-binding domain (DBD) to form a typical transcription factor – the DBD binds to target genes, while the ETO moiety contributes essentially to its transcriptional property. A direct comparative study of these “homologous” fusion transcription factors may clarify their similarities and differences in regulating transcription and leukemogenesis. Here, we performed a side-by-side comparison between AML1-ETO and ETO2-GLIS2, the most common fusion proteins in the M2 and M7 subtypes of acute myeloid leukemia, respectively, by inducible expression of them in U937 leukemia cells. We found that, although AML1-ETO and ETO2-GLIS2 can use their own DBDs (i.e., the Runt domain of AML1 and the zinc finger domain of GLIS2) to bind DNA, they actually share a large proportion of genome-wide binding regions dependent on other cooperative transcription factors such as ETS- and CEBP-family proteins. Functionally, AML1-ETO acts as either transcriptional repressor or activator, whereas ETO2-GLIS2 mainly acts as an activator. The repressor-versus-activator functions of AML1-ETO is determined by the abundance of cooperative transcription factors/cofactors on the target genes. Through these mechanisms, AML1-ETO and ETO2-GLIS2 differentially regulate several key transcription factors that are essential for myeloid differentiation. Indeed, AML1-ETO inhibits myeloid differentiation of U937 cells, whereas ETO2-GLIS2 facilitates it. Taken together, this study is the first direct comparative study between AML1-ETO and ETO2-GLIS2 in the same cellular context, and the results provide new insights into the context-dependent transcriptional regulatory mechanisms that may underlie how these seemingly “homologous” fusion transcription factors exert distinct functions to drive different subtypes of leukemia.
Project description:The ETO-family transcriptional corepressors, including ETO, ETO2 and MTGR1, are all involved in leukemia-causing chromosomal translocations. In every case, an ETO-family corepressor acquires a DNA-binding domain (DBD) to form a typical transcription factor – the DBD binds to target genes, while the ETO moiety contributes essentially to its transcriptional property. A direct comparative study of these “homologous” fusion transcription factors may clarify their similarities and differences in regulating transcription and leukemogenesis. Here, we performed a side-by-side comparison between AML1-ETO and ETO2-GLIS2, the most common fusion proteins in the M2 and M7 subtypes of acute myeloid leukemia, respectively, by inducible expression of them in U937 leukemia cells. We found that, although AML1-ETO and ETO2-GLIS2 can use their own DBDs (i.e., the Runt domain of AML1 and the zinc finger domain of GLIS2) to bind DNA, they actually share a large proportion of genome-wide binding regions dependent on other cooperative transcription factors such as ETS- and CEBP-family proteins. Functionally, AML1-ETO acts as either transcriptional repressor or activator, whereas ETO2-GLIS2 mainly acts as an activator. The repressor-versus-activator functions of AML1-ETO is determined by the abundance of cooperative transcription factors/cofactors on the target genes. Through these mechanisms, AML1-ETO and ETO2-GLIS2 differentially regulate several key transcription factors that are essential for myeloid differentiation. Indeed, AML1-ETO inhibits myeloid differentiation of U937 cells, whereas ETO2-GLIS2 facilitates it. Taken together, this study is the first direct comparative study between AML1-ETO and ETO2-GLIS2 in the same cellular context, and the results provide new insights into the context-dependent transcriptional regulatory mechanisms that may underlie how these seemingly “homologous” fusion transcription factors exert distinct functions to drive different subtypes of leukemia.
Project description:In the recent years, massively parallel sequencing approaches identified hundreds of mutated genes in cancer providing an unprecedented amount of information about mechanisms of cancer cell maintenance and progression. However, while (it is widely accepted that) transformation processes result from oncogenic cooperation between deregulated genes and pathways, the functional characterization of candidate key players is mostly performed at the single gene level which is generally inadequate to identify these oncogene circuitries. In addition, studies aimed at depicting oncogenic cooperation involve the generation of challenging mouse models or the deployment of tedious screening pipelines. Genome wide mapping of epigenomic modifications on histone tails or binding of factors such as MED1 and BRD4 allowed identification of clusters of regulatory elements, also termed Super-Enhancers (SE). Functional annotation of these regions revealed their high relevance during normal tissue development and cancer ontogeny. An interesting paradigm of the tumorigenic function of these SE regions comes from ETO2-GLIS2-driven acute megakaryoblastic leukemia (AMKL) in which the fusion protein ETO2-GLIS2 is sufficient to promote an aberrant transcriptional network by the rewiring of SE regions4. We thus hypothesized that important regulatory regions could control simultaneously expression of genes cooperating in functional modules to promote cancer development. In an effort to identify such modules, we deployed a genome-wide CRISPRi-based screening approach and nominated SE regions that are functionally linked to leukemia maintenance. In particular, we pinpointed a novel SE region regulating the expression of both tyrosine kinases KIT and PDGFRA. Whereas the inhibition of each kinase alone affected modestly cancer cell growth, combined inhibition of both receptors synergizes to impair leukemia cell growth and survival. Our results demonstrate that genome-wide screening of regulatory DNA elements can identify co-regulated genes collaborating to promote cancer and could open new avenues to the concept of combined gene inhibition upon single hit targeting.