Gene expression analysis to identify Runx1 target genes in B-cell progenitors

The t(12;21) chromosomal translocation, targeting the gene encoding the RUNX1 transcription factor, is observed in 25% of pediatric acute lymphoblastic leukemia (ALL) and is an initiating event in the disease. To elucidate the mechanism by which RUNX1 disruption initiates leukemogenesis, we investigated its normal role in murine B-cell development. Gene expression analysis and genome-wide Runx1-occupancy studies support the hypothesis that Runx1 reinforces the transcription factor network in B-cell progenitors governing early B-cell survival and development . 1) To identify Runx1 target genes in early B-cell progenitors, we used a whole genome microarray for analyzing the gene expression profile in a proB-cell line [BMiFLT3(15-3)] engineered to overexpresses the Runx1 transcription factor fused to the ligand binding domain of the estrogen receptor. The use of an inducible Runx1 fusion protein allowed specific translocation of Runx1 into the nucleus activation of Runx1 target genes. 2) To identify Runx1 target genes in early B-cell progenitors, we used a whole genome microarray for analyzing the gene expression profiles of proB-cells (CD19+/B220med/CD93+) isolated from Runx1+/+Cd79ahCre/+ and Runx1fl/flCd79ahCre/+ mice. Two independent experiments were peformed.