Ebf1 heterozygosity results in increased DNA damage in pro-B cells and their synergistic transformation by Pax5 haploinsufficiency

• Published in: Blood Vol. 125; no. 26; pp. 4052 - 4059
• Main Authors: Prasad, Mahadesh.A.J., Ungerbäck, Jonas, Åhsberg, Josefine, Somasundaram, Rajesh, Strid, Tobias, Larsson, Malin, Månsson, Robert, De Paepe, Ayla, Lilljebjörn, Henrik, Fioretos, Thoas, Hagman, James, Sigvardsson, Mikael
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 25-06-2015; American Society of Hematology
• Subjects: Animals; Blotting, Western; Cell Transformation, Neoplastic - genetics; Chromatin Immunoprecipitation; Clinical Medicine; Comet Assay; DNA Damage - genetics; Flow Cytometry; Fluorescent Antibody Technique; Haploinsufficiency - genetics; Hematologi; Hematology; Klinisk medicin; Lymphoid Neoplasia; Medical and Health Sciences; Medicin och hälsovetenskap; Mice; Mice, Inbred C57BL; Mice, Mutant Strains; PAX5 Transcription Factor - genetics; Precursor Cells, B-Lymphoid - metabolism; Reverse Transcriptase Polymerase Chain Reaction; Trans-Activators - genetics
• ISSN: 0006-4971; 1528-0020; 1528-0020
• DOI: 10.1182/blood-2014-12-617282

Early B-cell factor 1 (Ebf1) is a transcription factor with documented dose-dependent functions in normal and malignant B-lymphocyte development. To understand more about the roles of Ebf1 in malignant transformation, we investigated the impact of reduced functional Ebf1 dosage on mouse B-cell progenitors. Gene expression analysis suggested that Ebf1 was involved in the regulation of genes important for DNA repair and cell survival. Investigation of the DNA damage in steady state, as well as after induction of DNA damage by UV light, confirmed that pro-B cells lacking 1 functional allele of Ebf1 display signs of increased DNA damage. This correlated to reduced expression of DNA repair genes including Rad51, and chromatin immunoprecipitation data suggested that Rad51 is a direct target for Ebf1. Although reduced dosage of Ebf1 did not significantly increase tumor formation in mice, a dramatic increase in the frequency of pro-B cell leukemia was observed in mice with combined heterozygous mutations in the Ebf1 and Pax5 genes, revealing a synergistic effect of combined dose reduction of these proteins. Our data suggest that Ebf1 controls DNA repair in a dose-dependent manner providing a possible explanation to the frequent involvement of EBF1 gene loss in human leukemia.
•Ebf1 regulates DNA repair in a dose-dependent manner.•Combined heterozygote loss of Ebf1 and Pax5 predisposes for leukemia development.