Project description:This SuperSeries is composed of the following subset Series: GSE10520: Genes regulated by AML1/ETO in U937 cells GSE10537: Gene expression profiling of AML1/ETO regulated genes and binding pattern on human promoters in U937 cells GSE10578: AML1/ETO, AML1, and HEB binding patterns on chromosme 19 GSE10579: Analysis of expression levels of genes on chromosome 19 in U937 cells expressing AML1/ETO Keywords: SuperSeries Refer to individual Series
Project description:The AML1/ETO fusion protein is essential to the development of acute myeloid leukemia (AML), and is well recognized for its dominant-negative effect on the co-existing wild-type protein AML1. However, the involvement of wild-type AML1 in AML1/ETO-driven leukemogenesis remains elusive. Through chromatin immunoprecipitation sequencing, computational analysis plus a series of experimental validations, we report here that AML1 is able to orchestrate the expression of AML1/ETO targets regardless of being activated or repressed, via forming a complex with AML1/ETO and via recruiting the cofactor. 4 ChIP-seq assays were used to identify the high confidence binding regions of AML1-ETO and AML1 in t(8;21) AML Kasumi-1 cell lines. The anti-AML1 (N20) antibody targets the N-terminus of AML1 and recognizes both AML1 and AML1/ETO; the anti-AML1 (C19) antibody targets the C-terminus of AML1 and recognizes AML1 but not AML1/ETO; the anti-ETO (C20) antibody targets the C-terminus of ETO and specifically recognizes AML1/ETO. 2 ChIP-seq assays were used to identify the binding regions of AML1 in human macrophage U937 cell lines. And the total input was used as control.
Project description:Approximately 20% of Acute Myelogenous Leukemia (AML) cases carry the t(8;21) translocation, which involves the AML1 and ETO genes, and express the resulting AML1/ETO fusion protein that functions as a transcriptional repressor by recruiting NCoR/SMRT/HDAC complexes to DNA. We used microarrays to identify human promoters bound by AML1/ETO in U937 cells. Keywords: ChIP-chip
Project description:In an effort to identify novel drugs targeting fusion-oncogene induced acute myeloid leukemia (AML), we performed high-resolution proteomic analysis. In AML1-ETO (AE) driven AML we uncovered a deregulation of phospholipase C (PLC) signaling. We identified PLCgamma 1 (PLCG1) as a specific target of the AE fusion protein which is induced after AE binding to intergenic regulatory DNA elements. Genetic inactivation of PLCG1 in murine and human AML inhibited AML1-ETO dependent self-renewal programs, leukemic proliferation, and leukemia maintenance in vivo. In contrast, PLCG1 was dispensable for normal hematopoietic stem- and progenitor cell function. These findings are extended to and confirmed by pharmacologic perturbation of Ca++-signaling in AML1-ETO AML cells, indicating that the PLCG1 pathway poses an important therapeutic target for AML1-ETO positive leukemic stem cells.
Project description:Approximately 20% of Acute Myelogenous Leukemia (AML) cases carry the t(8;21) translocation, which involves the AML1 and ETO genes, and express the resulting AML1/ETO fusion protein that functions as a transcriptional repressor by recruiting NCoR/SMRT/HDAC complexes to DNA. We used ChIP-chip to identify the determinants of AML1/ETO binding on a contiguous DNA region (chromosome 19). AML1/ETO binding regions are characterized by a specific sequence signature that includes the presence of the consensus binding sites for the AML1 and HEB transcription factors. We therefore assessed the binding patterns of AML1 and HEB on chromosome 19. A specific chromatin modification (tri-methylation of lysine 4 on histone 3 = 3MetK4) was also studied in U937 cells expressing AML1/ETO in order to correlate the identified binding profiles with active transcription sites. Keywords: ChIP-chip
Project description:Approximately 20% of Acute Myelogenous Leukemia (AML) cases carry the t(8;21) translocation, which involves the AML1 and ETO genes, and express the resulting AML1/ETO fusion protein that functions as a transcriptional repressor by recruiting NCoR/SMRT/HDAC complexes to DNA. We used microarrays to identify human promoters bound by AML1/ETO in U937 cells. Keywords: ChIP-chip A U937 cell line that conditionally expresses HA-tagged AML1/ETO under the control of the mouse metallothionine promoter (U937-A1E) (Alcalay et al., J.Clin.Invest, 2003,112, 1751-1761) was used. Cells were treated for 8h with 100uM ZnSO4 to induce transgene expression, and ChIP was performed using an anti-HA antibody. ChIP products were then PCR amplified, labeled with Cy3/Cy5 fluorescent dyes and hybridized to the NimbleGen HG17 Human Promoter 2 Array set, which explores 4 kb upstream and 1 kb downstream the transcription start site (TSS) of 24,434 annotated genes. Two biological replicates were prepared and hybridized to independent array sets. U937-Mt cells, which carry the empty vector, served as control for non-specific binding of the anti-HA antibody.
Project description:The t(8;21) acute myeloid leukemia associated oncoprotein AML1-ETO is a transcription factor that aberrantly regulates the pathways that lead to myeloid differentiation. Here, we set out to investigate the effects of AML1-ETO on gene expression and the epigenome in patient blast cells. We identify two modules, one in which AML1-ETO binds promoter regions of active genes and one represented by non-promoter binding to accessible, yet inactive chromatin regions. Using genome-wide binding analysis and mass spectrometry interaction studies we identify ERG, FLI1, TAL1 and RUNX1 as common binding factors of all AML1-ETO occupied genomic regions, while LYL1 and LMO2 show preferential binding in the context of non promoter regions. Epigenetically, reduced histone acetylation levels at non-promoter regions seems HDAC dependent, as treatment with an HDACi increases acetylation and induces cell death. Both AML1-ETO modules are represented in most aberrantly regulated pathways, including many signaling pathways, self-renewal and apoptosis. For the latter, the expression of the wild type transcription factors RUNX1 and ERG is required, as alterations in expression are associated with the onset of an apoptosis program. Interestingly, upon RUNX1 or ERG knockdown this onset seems to be dependent on increased AML1-ETO expression as combinatorial knockdown of RUNX1/AML1-ETO or ERG/AML1-ETO results in rescue from apoptosis. Together our results show that the balanced interplay of the epigenetic environment and transcription factors retains an anti apoptotic phenotype in t(8;21) AML cells.