A Bach2-Cebp Gene Regulatory Network for the Commitment of Multipotent Hematopoietic Progenitors.

ABSTRACT

Hematopoietic stem cell and multipotent progenitor (MPP) commitment can be tuned in response to an infection so that their differentiation is biased toward myeloid cells. Here, we find that Bach2, which inhibits myeloid differentiation in common lymphoid progenitors, represses a cohort of myeloid genes and activates those linked to lymphoid function. Bach2 repressed both Cebpb and its target Csf1r, encoding C/EBPß and macrophage colony-stimulating factor receptor (M-CSFr), respectively, whereas C/EBPß repressed Bach2 and activated Csf1r. Bach2 and C/EBPß further bound to overlapping regulatory regions at their myeloid target genes, suggesting the presence of a gene regulatory network (GRN) with mutual repression between these factors and a feedforward loop leading to myeloid gene regulation. Lipopolysaccharide reduced the expression of Bach2, resulting in enhanced myeloid differentiation. The Bach2-C/EBPß GRN pathway thus tunes MPP commitment to myeloid and lymphoid lineages both under normal conditions and after infection.