Identification of genome wide Hoxa9 binding sites in primary murine and human AML cells
ABSTRACT: Relative overexpression of HOXA9 is a key feature of aggressive AML (acute myeloid leukemia). Here we determined genome wide binding sites of Hoxa9 in primary murine cells transformed by Hoxa9 and in a human AML cell line. In addition global H3K4 monomethylation and H3K27acetylation levels were determined in cells transformed by an inducible Hoxa9-ER construct in Hoxa9-active conditions and 72h after Hoxa9 was inactivated.
Project description:Relative overexpression of HOXA9 is a key feature of aggressive AML (acute myeloid leukemia). Hoxa9 responsive genes were identified by nascent RNA sequencing (4-thio-uridine labeled RNA - sequencing) in samples of primary hematopoietic precursor cells from mice transformed by an tamoxifen inducible version of Hoxa9 (Hoxa9-ER). Samples were generated in the presence of active Hoxa9 (0h) and in a time series after Hoxa9 was inactivated at 8h, 16h, 24h, 48h, and 72h.
Project description:Identification of the genome-wide binding sites of Hoxa9 and C/EBPα in a murine myeloblastic cell line transformed by Hoxa9/Meis1. Over 50% of Hoxa9 binding sites are co-bound by C/EBPα, providing mechanistic insight into the requirement of C/EBPα for Hoxa9-mediated leukemogenesis. Additionally, genome-wide occupancy of H3K4 monomethylation and H3K27 trimethylation provide additional information on the functionality of Hoxa9/C/EBPα cobound loci. Examination of two transcription factor binding sites and two histone modifications in a transformed cell line.
Project description:Meis1 is found cooperatively activated with Hoxa7/a9 in AML, and it indeed promotes leukemogenic activities of Hoxa9. It is important to identify downstream target genes of Meis1 to understand its cooperative activity with Hoxa9 in leukemogenesis. We used microarrays to detail the global programme of gene expression upon Meis1 knockout. Overall design: Murine primary bone marrow cells of the Rosa26-Cre-ERT2 knock-in mouse were transformed by retroviral transduction of Hoxa9 and floxed Meis1. The immortalized bone marrow cells were treated with 2 μM of 4-hydroxytamoxifen to delete Meis1 cDNA. Gene expression profiles were compared between the original Hoxa9/Meis1-expressing cells and Meis1 deleted (Hoxa9 only) cells.
Project description:Meis1 is found cooperatively activated with Hoxa7/a9 in AML, and it indeed promotes leukemogenic activities of Hoxa9. It is important to identify downstream target genes of Meis1 to understand its cooperative activity with Hoxa9 in leukemogenesis. We used microarrays to detail the global programme of gene expression upon Meis1 knockout. Murine primary bone marrow cells of the Rosa26-Cre-ERT2 knock-in mouse were transformed by retroviral transduction of Hoxa9 and floxed Meis1. The immortalized bone marrow cells were treated with 2 μM of 4-hydroxytamoxifen to delete Meis1 cDNA. Gene expression profiles were compared between the original Hoxa9/Meis1-expressing cells and Meis1 deleted (Hoxa9 only) cells.
Project description:Characterization of gene expression changes 72 hours after withdrawal of tamoxifen in murine hematopoietic progenitors transformed by Hoxa9-ER/Meis1 using RNAseq. In the presence of tamoxifen (4OHT), Hoxa9-ER localizes to the nucleus of cells allowing for transformation, while withdrawal of 4OHT (culture in EtOH) leads to loss of nuclear Hoxa9-ER. Loss of Hoxa9-ER leads to a decrease in cellular proliferation and differentiation along the myeloid lineage. Examination of gene expression by RNAseq in two conditions in biological replicates.
Project description:The clustered homeobox proteins play crucial roles in development, hematopoiesis and leukemia yet the targets they regulate and their mechanisms of action are poorly understood. Here, we identified the binding sites for Hoxa9 and the Hox cofactor Meis1 on a genome-wide level and profiled their associated epigenetic modifications and transcriptional targets. Hoxa9 and the Hox cofactor Meis1 co-bind at hundreds of highly evolutionarily-conserved sites, most of which are distant from transcription start sites. These sites show high levels of histone H3K4 monomethylation and CBP/P300 binding characteristic of enhancers. Furthermore, a subset of these sites shows enhancer activity in transient transfection assays. Many Hoxa9 and Meis1 binding sites are also bound by PU.1 and other lineage-restricted transcription factors previously implicated in establishment of myeloid enhancers. Conditional Hoxa9 activation is associated with CBP/P300 recruitment, histone acetylation and transcriptional activation of a network of proto-oncogenes including Erg, Flt3, Lmo2, Myb and Sox4. Collectively this work suggests that Hoxa9 regulates transcription by interacting with enhancers of genes important for hematopoiesis and leukemia. To identify the genome-wide binding sites for Hoxa9 and the Hox cofactor Meis1
Project description:We have cloned and characterized a fusion gene NUP98/HHEX1 resulting from t(7;10) from a patient with acute myeloid leukemia (AML). As NUP98/HHEX acts as an aberrant transcriptional activator, putative targets were searched upon transient expression of the fusion in primary murine bone marrow cells. Experiment Overall Design: Murine bone marrow cells were transduced with a retrovirus (MSCV-IRES-GFP, MIG) expressing either NUP98/HHEX or NUP98/HOXA9 (or the empty vector), mRNA was isolated after 72h. Each experiment was performed in triplicates.
Project description:Analysis of gene expression profile of Hoxa9/Meis1 leukemia cells 6 days after loss of Jmjd1c. Loss of Jmjd1c induces differentiation and Hoxa9/Meis1 leukemia cells. These results provide insight into the role of Jmjd1c in AML with elelvated expression of Hoxa9. Overall design: We used primary Jmjd1c f/f Hoxa9/Meis1 neo leukemia cells from three leukemic mice and delivered Cre-Tomato by retroviral infection. We sorted Tomato positive cells 6 days after Cre infection and subjected the samples to RNA-seq.
Project description:Leukemias that harbor translocations involving the mixed lineage leukemia gene (MLL) possess unique biological characteristics and often have an unfavorable prognosis. Gene expression analyses demonstrate a distinct profile for MLL-rearranged leukemias with consistent high-level expression of select Homeobox genes including HOXA9. Here, we investigated the effects of HOXA9 suppression in MLL-rearranged and MLL-germline leukemias utilizing RNAi. Gene expression profiling after HOXA9 suppression demonstrated co-downregulation of a program highly expressed in human MLL-AML (this study) and murine MLL-leukemia (Krivtsov et al. 2006) stem cells including HOXA10, MEIS1, PBX3 and MEF2C. Our data indicates an important role for HOXA9 in human MLL-rearranged leukemias, and suggests targeting HOXA9 or downstream programs may be a novel therapeutic option. Overall design: RNA was purified from t(9;11) MOLM-14 AML cells 44h after transduction in triplicates with 2 of the two most effective HOXA9shRNA constructs (3 x 1F3-HOXA9shRNA; 3 x 2A5-HOXA9shRNA) or GFP-controlshRNA (6x).