Genome-wide co-occupancy of Hoxa9 and C/EBPα in Hoxa9/Meis1 transformed HSCs [ChIP-seq]
ABSTRACT: 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.
Proceedings of the National Academy of Sciences of the United States of America 20140623 27
Homeobox A9 (HOXA9) is a homeodomain-containing transcription factor that plays a key role in hematopoietic stem cell expansion and is commonly deregulated in human acute leukemias. A variety of upstream genetic alterations in acute myeloid leukemia (AML) lead to overexpression of HOXA9, almost always in association with overexpression of its cofactor meis homeobox 1 (MEIS1) . A wide range of data suggests that HOXA9 and MEIS1 play a synergistic causative role in AML, although the molecular mech ...[more]
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:RNAseq characterization of gene expression changes 72 hours after genomic excision of Cebpa in murine hematopoietic progenitors from Cebpaf/f;CreER mice transformed by Hoxa9/Meis1. In the presence of tamoxifen (4OHT), Cre-ER localizes to the nucleus of cells allowing for excision of Cebpa and loss of C/EBPα protein levels. Loss of C/EBPα leads to a decrease in cellular proliferation. Examination of gene expression by RNAseq in two conditions in biological replicates.
Project description: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:This SuperSeries is composed of the following subset Series: GSE21299: Expression data from murine cell line transduced with epitope tagged forms of Hoxa9 GSE33509: Identification and Characterization of Hoxa9 Binding Sites in Hematopoietic Cells GSE33517: Epigenetic profiling of histone H3K4me1, H3K4me3, H3K27me3, H3ac, H4ac, CBP and P300 using ChIP-chip Refer to individual Series
Project description:To study the oncogenic mechanism triggered by the leukemic fusion protein NUP98-HOXA9, we cloned the cDNA of NUP98-HOXA9 into a retroviral vector (pMSCV-IRES-GFP) and efficiently transduced the HEK293FT human cell line. We performed a ChIP-seq analysis to identify the DNA binding sites of NUP98-HOXA9. These results allowed us to demonstrate that NUP98-HOXA9 regulates the expression of genes involved in the development of Acute Myeloid Leukemia by directly interacting with their enhancer regions. We further investigated the functional contribution to the DNA binding profile of the two moieties that compose the fusion protein. We cloned the coding region of HOXA9 wt and NUP98 wt in the same retroviral vector, established two new cellular models, 293FT-HOXA9 and 293FT-NUP98, and performed separate ChIP-seq analyses. We demonstrated that both moieties contribute importantly to the regulation of the target genes. Overall design: Identification of NUP98-HOXA9, HOXA9 and NUP98 specific DNA binding sites in human cellular models
Project description:We used chromatin immunoprecipitation combined with deep sequencing to map all binding sites of C/EBPα and PPARγ in human SGBS adipocytes and compared these with the genome-wide profiles from mouse 3T3-L1 adipocytes to systematically investigate what biological features correlate with retention of sites in orthologous regions between mouse and human. Despite a limited interspecies retention of binding sites, several biological features make sites more likely to be retained. First, co-binding of PPARγ and C/EBPα in mouse is the most powerful predictor of retention of the corresponding binding sites in human. Second, vicinity to genes highly upregulated during adipogenesis significantly increases retention. Third, the presence of C/EBPα consensus sites correlate with retention of both factors, indicating that C/EBPα facilitates recruitment of PPARγ. Fourth, retention correlates with overall sequence conservation within the binding regions independent of C/EBPα and PPARγ sequence patterns, indicating that other transcription factors work cooperatively with these two key transcription factors. C/EBPα and PPARγ ChIP-seq in mouse 3T3-L1 and human SGBS adipocytes.
Project description:We have searched genome-wide binding sites of homeodomain proteins important for leukemogenesis in Hoxa9- and Meis1- induced myeloid leukemia cells. Thousands of binding sites of these three family proteins have been identified and many of them are co-localized with those of each others. Hoxa9 and Pbx binding sites were compared between the presence and absence of Meis1 by its knockout in the same cells. In combination of the results with gene expression profiles of the same cells, important downstream target genes of Meis1 in leukemogenesis have been identified. Overall design: Examination of binding sites of 3 transcription factors in a single cell with 2 different conditions