Identification and characterization of Hoxa9 binding sites in hematopoietic cells

• Published in: Blood Vol. 119; no. 2; pp. 388 - 398
• Main Authors: Huang, Yongsheng, Sitwala, Kajal, Bronstein, Joel, Sanders, Daniel, Dandekar, Monisha, Collins, Cailin, Robertson, Gordon, MacDonald, James, Cezard, Timothee, Bilenky, Misha, Thiessen, Nina, Zhao, Yongjun, Zeng, Thomas, Hirst, Martin, Hero, Alfred, Jones, Steven, Hess, Jay L.
• Format: Journal Article
• Language: English
• Published: Washington, DC Elsevier Inc 12.01.2012; Americain Society of Hematology; American Society of Hematology
• Subjects: Acetylation; Animals; Binding Sites; Biological and medical sciences; Biomarkers, Tumor - genetics; Biomarkers, Tumor - metabolism; Blotting, Western; Bone Marrow Cells - metabolism; Chromatin Immunoprecipitation; Enhancer Elements, Genetic; Epigenomics; Female; Gene Expression Profiling; Gene Expression Regulation, Leukemic; Hematologic and hematopoietic diseases; Hematopoiesis - physiology; Hematopoiesis and Stem Cells; Homeodomain Proteins - genetics; Homeodomain Proteins - metabolism; Leukemia - genetics; Leukemia - metabolism; Medical sciences; Mice; Mice, Inbred C57BL; Myeloid Ecotropic Viral Integration Site 1 Protein; Neoplasm Proteins - genetics; Neoplasm Proteins - metabolism; Oligonucleotide Array Sequence Analysis; Real-Time Polymerase Chain Reaction; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger - genetics; Transcription Factors - genetics; Transcription Factors - metabolism; Hematology; Hematopoietic cell; Binding site
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood-2011-03-341081

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 cobind 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.