Transcriptomic analysis of Bmi1 overexpression in NSPC

We have previously shown that conditional overexpression of Bmi1 in NSC increases their proliferation both in the developing neocortexand in the postnatal brain (Yadirgi et al. 2011). However, during embryonic development, increased and ectopic proliferation induced by overexpression of Bmi1 in progenitors committed toward a neuronal lineage triggered apoptosis, leading eventually to a reduced overall brain size (Yadirgi et al. 2011). These findings –increased proliferation of neural stem/progenitor cells (NSPC) and apoptosis of neuronal committed progenitors - could be faithfully reproduced in an in vitro assay where NSPC isolated from Nestin-Cre; STOP FloxBmi1 embryos are cultured in floating conditions in the presence of EGF and FGF2 (neurosphere assay). We isolated NSPC from Nestin-Cre;STOP FloxBmi1 E16.5 neocortices and cultured them briefly under neurosphere inducing conditions. We then analysed their transcriptome by whole-genome Illumina platform mouse v2 and compared it to the transcriptome of NSPC isolated from non-transgenic or single transgenic littermates. The objective of this analysis was to identify genes differentially expressed upon overexpression of the PcG gene Bmi1 in neural stem/progenitor cells. 4 samples, 2 condition with 2 biological replicates per condition