Fig 2: Ectopic expression of Hoxa9, but not Bmi1, in fetal liver progenitors antagonizes B-lymphoid differentiation.(A) Analysis by qRT-PCR of Hoxa9 and Bmi1 gene expression in E2A-PBX1- versus vector-infected FLPs. Values for each gene are expressed relative to expression in vector-infected cells. (B) Immunophenotype of FLPs transduced with Hoxa9- versus Bmi1-expressing retroviruses. Lin- FLPs were transduced with retroviruses expressing Bmi1 or Hoxa9 and then cultured under B-lymphoid conditions. Cells were analyzed by flow cytometry on day 14 post-infection.

Fig 3: FLPs expressing E2A-PBX1 remain amenable to induction of myeloid differentiation in vivo or in vitro.E2A-PBX1-transduced FLPs were injected into the tail veins of lethally-irradiated mice. Immunophenotypic analysis was performed on cells obtained from the bone marrow (A) or spleen (B) 3 weeks later. (C) E2A-PBX1 expressing FLPs were transferred from medium containing IL-7 and SCF to medium containing GM-CSF instead and analyzed by flow cytometry 7 days later.

Fig 4: Forced expression of E2A-PBX in FLPs deregulates hematopoietic genes.(A) Hierarchical cluster analysis performed on expression data from gene expression microarrays indicates that the closest relationship to E2A-PBX1-expressing FLPs is with pro-B-cells that were differentiated from FLPs in vitro. (B) Confirmation by qRT-PCR of differential expression of genes identified initially using expression microarrays in E2A-PBX-expressing versus pro-B-cells derived from vector-infected FLPs. Data are from 2 independent samples. Error bars indicate one standard deviation; p-values are less than 0.005 for each comparison.

Fig 5: E2A-PBX1-expressing bone marrow cells reconstitute early myeloid but not B-lymphoid development in transplanted mice.Primary murine bone marrow cells were transduced with E2A-PBX1-expressing or control retroviral vectors and injected into the tail vein of lethally-irradiated, syngeneic recipient mice. Mice were sacrificed 3 weeks later. Immunophenotypic analysis of (A) bone marrow, (B) spleen, and (C) thymus are shown from representative animals. Events were gated so as to restrict all of these analyses to the GFP+ cell population.