Integrating Enhancer Mechanisms to Establish a Hierarchical Blood Development Program
Charu Mehta,
Kirby D. Johnson,
Xin Gao,
Irene M. Ong,
Koichi R. Katsumura,
Skye C. McIver,
Erik A. Ranheim,
Emery H. Bresnick
Affiliations
Charu Mehta
UW-Madison Blood Research Program, Department of Cell and Regenerative Biology, Wisconsin Institutes for Medical Research, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705, USA
Kirby D. Johnson
UW-Madison Blood Research Program, Department of Cell and Regenerative Biology, Wisconsin Institutes for Medical Research, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705, USA
Xin Gao
UW-Madison Blood Research Program, Department of Cell and Regenerative Biology, Wisconsin Institutes for Medical Research, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705, USA
Irene M. Ong
UW Carbone Cancer Center, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705, USA
Koichi R. Katsumura
UW-Madison Blood Research Program, Department of Cell and Regenerative Biology, Wisconsin Institutes for Medical Research, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705, USA
Skye C. McIver
UW-Madison Blood Research Program, Department of Cell and Regenerative Biology, Wisconsin Institutes for Medical Research, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705, USA
Erik A. Ranheim
Department of Pathology, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705, USA
Emery H. Bresnick
UW-Madison Blood Research Program, Department of Cell and Regenerative Biology, Wisconsin Institutes for Medical Research, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705, USA
Hematopoietic development requires the transcription factor GATA-2, and GATA-2 mutations cause diverse pathologies, including leukemia. GATA-2-regulated enhancers increase Gata2 expression in hematopoietic stem/progenitor cells and control hematopoiesis. The +9.5-kb enhancer activates transcription in endothelium and hematopoietic stem cells (HSCs), and its deletion abrogates HSC generation. The −77-kb enhancer activates transcription in myeloid progenitors, and its deletion impairs differentiation. Since +9.5−/− embryos are HSC deficient, it was unclear whether the +9.5 functions in progenitors or if GATA-2 expression in progenitors solely requires −77. We further dissected the mechanisms using −77;+9.5 compound heterozygous (CH) mice. The embryonic lethal CH mutation depleted megakaryocyte-erythrocyte progenitors (MEPs). While the +9.5 suffices for HSC generation, the −77 and +9.5 must reside on one allele to induce MEPs. The −77 generated burst-forming unit-erythroid through the induction of GATA-1 and other GATA-2 targets. The enhancer circuits controlled signaling pathways that orchestrate a GATA factor-dependent blood development program.
