Zebrafish CbfbIs Required For The Mobilization, But Not The Emergence, Of Hematopoietic Stem Cells In Embryos

CBFβ and RUNX1 form a DNA-binding heterodimer that plays a crucial role during definitive hematopoiesis at the stage of hematopoietic stem cells (HSCs). Both of them are targets of recurrent chromosomal translocations in human leukemia. In mammals and zebrafish, RUNX1 is required for the emergence of definitive HSCs from the hemogenic endothelium. Mouse knockouts for either Runx1or Cbfbshow similar phenotypes with complete lack of definitive hematopoiesis. Therefore, the impairment of all definitive hematopoietic lineages in both Runx1-/-and Cbfb-/-embryos suggested that the CBF heterodimer is required for HSC formation. However the exact role of the CBF complex in the development of HSCs remains unclear.