Neutrophilic differentiation is dependent on CCAAT enhancer-binding protein α (C/EBPα), a transcription factor expressed in multiple organs including the bone marrow. Using functional genomic technologies in combination with clustered regularlyinterspaced short palindromic repeat (CRISPR)/CRISPR-associated protein 9 genome editing and in vivo mouse modeling, we show that CEBPA is located in a 170-kb topological-associated domain that contains 14 potential enhancers. Of these, 1 enhancer located 142 kb from CEBPA is active and engages with the CEBPA promoter in myeloid cells only.
Germ line deletion of the homologous enhancer in mice in vivo reduces Cebpa levels exclusively in hematopoietic stem cells (HSCs) andmyeloid-primed progenitor cells leading to severe defects in the granulocytic lineage, without affecting any other Cebpaexpressing organ studied. The enhancer-deleted progenitor cells lose their myeloid transcriptionprogramandareblockedindifferentiation. Deletionof theenhancer alsocausesloss of HSC maintenance. We conclude that a single 142-kb enhancer is essential for CEBPA expression in myeloid cells only. 695759,
Department of Hematology

Avellino, R., Havermans, M., Erpelinck, C., Sanders, M., Hoogenboezem, R., van de Werken, H., … Delwel, R. (2016). An Autonomous CEPBA enhancer specific for myeloid-lineage priming and neutrophilic differentiation. Blood, 127(24), 2991–3003. doi:10.1182/blood-2016-01- 695759