GSE159957
EBF1 and PAX5 control pro-B cell expansion via oppose regulation of the Myc gene
Lineage restricted transcription factors are frequently found mutated in B-lymphoid leukemia, suggesting a close link between normal and malignant B-cell development. One of these transcription factors is EBF1, a protein of critical importance for specification but also survival of B-lymphoid progenitors. We here report that impaired EBF1 function in mouse B-cell progenitors results in reduced expression of Myc. Ectopic expression of MYC rescued B-cell expansion in the absence of EBF1 both in vivo and in vitro. Using chromosome conformation analysis in combination with ATAC, ChIP-seq and reporter gene assays, identified six EBF responsive enhancer elements that could be annotated to the Myc gene. Crispr-Cas9 mediated targeting of EBF1 binding sites identified one element of importance for Myc expression and pro-B cell expansion providing evidence for that Myc is a direct target for EBF1. Furthermore, ChIP-seq analysis suggested that several regulatory elements in the Myc gene were targeted by PAX5. However, ectopic expression of PAX5 in EBF1 deficient cells was found to induce a cell cycle block and reduce Myc expression suggesting that EBF1 and PAX5 act in an opposing manner at this shared target gene. This hypothesis was further substantiated by the finding that Pax5 inactivation reduced the need for EBF1 in pro-B cell expansion. The binding of EBF1 and PAX5 to regulatory elements in the human MYC gene in a B-ALL cell line indicate that this regulatory loop may be of relevance for our understanding of both normal and malignant B-cell development.   Overall design: Murine B-cell progenitor cell lines or cultured primary cells of Wt, Ebf1-KO or Pax5-KO genotype were subject to Ebf1-ChIP seq analysis, H3K4me3 PLAC seq or RNA-seq after  transduction vectors expressing Ebf1 or Pax5.