Runx1-mediated hematopoietic stem-cell emergence is controlled by a Gata/Ets/SCL-regulated enhancer

• Published in: Blood Vol. 110; no. 13; pp. 4188 - 4197
• Main Authors: Nottingham, Wade T., Jarratt, Andrew, Burgess, Matthew, Speck, Caroline L., Cheng, Jan-Fang, Prabhakar, Shyam, Rubin, Eddy M., Li, Pik-Shan, Sloane-Stanley, Jackie, Kong-a-San, John, de Bruijn, Marella F.T.R.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 15.12.2007; American Society of Hematology
• Series: Hematopoiesis
• Subjects: Adaptor Proteins, Signal Transducing; Animals; Basic Helix-Loop-Helix Transcription Factors - metabolism; Basic Helix-Loop-Helix Transcription Factors - physiology; Core Binding Factor Alpha 2 Subunit - genetics; Core Binding Factor Alpha 2 Subunit - physiology; DNA-Binding Proteins - metabolism; Embryo, Mammalian; Enhancer Elements, Genetic - physiology; GATA2 Transcription Factor - metabolism; GATA2 Transcription Factor - physiology; Hematopoiesis; Hematopoietic Stem Cells - cytology; LIM Domain Proteins; Metalloproteins - metabolism; Mice; Multiprotein Complexes - metabolism; Proto-Oncogene Protein c-ets-1 - metabolism; Proto-Oncogene Protein c-ets-1 - physiology; Proto-Oncogene Proteins - metabolism; Proto-Oncogene Proteins - physiology; T-Cell Acute Lymphocytic Leukemia Protein 1; Transcription, Genetic
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood-2007-07-100883

The transcription factor Runx1/AML1 is an important regulator of hematopoiesis and is critically required for the generation of the first definitive hematopoietic stem cells (HSCs) in the major vasculature of the mouse embryo. As a pivotal factor in HSC ontogeny, its transcriptional regulation is of high interest but is largely undefined. In this study, we used a combination of comparative genomics and chromatin analysis to identify a highly conserved 531-bp enhancer located at position + 23.5 in the first intron of the 224-kb mouse Runx1 gene. We show that this enhancer contributes to the early hematopoietic expression of Runx1. Transcription factor binding in vivo and analysis of the mutated enhancer in transient transgenic mouse embryos implicate Gata2 and Ets proteins as critical factors for its function. We also show that the SCL/Lmo2/Ldb-1 complex is recruited to the enhancer in vivo. Importantly, transplantation experiments demonstrate that the intronic Runx1 enhancer targets all definitive HSCs in the mouse embryo, suggesting that it functions as a crucial cis-regulatory element that integrates the Gata, Ets, and SCL transcriptional networks to initiate HSC generation.