Expression data from C/EBP alpha induced transdifferentiation of pre-B cells into macrophages. Mus musculus

Earlier work has shown that pre-B cells can be converted into macrophages by the transcription factor C/EBP? at very high frequencies. Using this system we have now performed a systematic analysis of the question whether during transdifferentiation the cells transiently reactivate progenitor restricted genes or even retrodifferentiate. A transcriptome analysis of transdifferentiating cells showed that most genes are continuously up or downregulated, acquiring a macrophage phenotype within 5 days. In addition, we observed the transient reactivation of a subset of immature myeloid markers, as well as low levels of the progenitor markers Kit and Flt3 and a few lineage inappropriate genes. However, we were unable to observe the re-expression of cell surface marker combinations that characterize hematopoietic stem and progenitor cells (HSPCs), including c-Kit and Flt3. This was the case even when C/EBPalpha was activated in pre-B cells under culture conditions that favor HSPC growth or when the transcription factor was activated in a time limited fashion. Together, our findings are consistent with the notion that the conversion from pre-B cells to macrophages is mostly direct and does not involve overt retrodifferentiation. Our microarray data indicate that most expression changes are direct, and that transdifferentiation does not involve retrodifferentiation. Our data also show that there is a low level transient activation of selected progenitor genes, as well as myeloid precursor genes. Overall design: Primary mouse pre-B cells were infected with an inducible form of C/EBPa and cells induced to transdifferentiate with beta Estradiol (b-Est) harvested at different time points to analyze expression profiles, using Affymetrix 430.2 arrays.