title: Cbfbeta-SMMHC impairs differentiation of common lymphoid progenitors and reveals an essential role for RUNX in early B-cell development.
abstract: The core-binding factor (CBF)-associated leukemia fusion protein CBFbeta-SMMHC impairs myeloid and lymphoid differentiation. By inhibiting RUNX function, the fusion oncoprotein predisposes specifically to acute myeloid leukemia in both patients and mouse models. We have shown that Cbfbeta-SMMHC expression leads to a sustained reduction of circulating B lymphocytes in the mouse. In this study, we demonstrate that the activation of Cbfbeta-SMMHC reduces pre-pro-B cells approximately 3-fold and pre-B cells more than 10-fold and that this differentiation block is cell-autonomous. The reduction of pre-pro-B cells coincided with an increase in apoptosis in this population. The number of common lymphoid progenitors (CLPs) were not affected; however, the expression of critical early B-cell factors Ebf1, Tcfe2a, and Pax5 was significantly reduced. In addition, Cbfbeta-SMMHC reduced Rag1 and Rag2 expression and impaired V(D)J recombination in the CLPs. Furthermore, CLPs expressing Cbfbeta-SMMHC also show inhibition of B cell-specific genes Cd79a, Igll1, VpreB1, and Blk. These results demonstrate that CBF/RUNX function is essential for the function of CLPs, the survival of pre-pro-B cells, and the establishment of a B lineage-specific transcriptional program. This study also provides a mechanistic basis for the myeloid-lineage bias of CBFbeta-SMMHC-associated leukemia.
authors.affiliation: Program in Gene Function and Expression, University of Massachusetts Medical School, Worcester, MA 01605, USA.
authors.forename: Ya-Huei
authors.initials: YH
authors.lastname: Kuo
authors.forename: Rachel M
authors.initials: RM
authors.lastname: Gerstein
authors.forename: Lucio H
authors.initials: LH
authors.lastname: Castilla
mesh_terms: D000818:Animals; D002454:Cell Differentiation; D019070:Cell Lineage; D050657:Core Binding Factor alpha Subunits / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism; D018398:Homeodomain Proteins / Q000378:metabolism; D054503:Lymphoid Progenitor Cells / Q000166:cytology* / Q000378:metabolism*; D051379:Mice; D008822:Mice, Transgenic; D015514:Oncogene Proteins, Fusion / Q000235:genetics / Q000378:metabolism*; D012680:Sensitivity and Specificity; D014158:Transcription, Genetic / Q000235:genetics; D045567:VDJ Recombinases / Q000235:genetics / Q000378:metabolism
chemical_list: C095514:CBFbeta-MYH11 fusion protein; D050657:Core Binding Factor alpha Subunits; D004268:DNA-Binding Proteins; D018398:Homeodomain Proteins; D015514:Oncogene Proteins, Fusion; C499308:Rag2 protein, mouse; C064658:RAG-1 protein; D045567:VDJ Recombinases