Expression data from single cells from mouse primordial germ cell lineage (E6.25-E8.25, wild type and Blimp1KO)

Specification of germ cell fate is fundamental in development. With a highly representative single-cell microarray and rigorous quantitative-PCR analysis, we defined the genome-wide transcription dynamics that create primordial germ cells (PGCs) from the epiblast, a process that exclusively segregates them from their somatic neighbors. We also analyzed the effect of the loss of Blimp1, a key transcriptional regulator, on these dynamics. Our analysis revealed that PGC specification involves complex, yet highly ordered regulation of a large number of genes, proceeding under the strong influence of mesoderm induction with active repression of specific programs such as epithelial-mesenchymal transition, Hox gene activation, cell-cycle progression and DNA methyltransferase machinery. Remarkably, Blimp1 is essential for repressing nearly all the genes normally down-regulated in PGCs relative to their somatic neighbors, whereas it is dispensable for the activation of approximately half of the genes up-regulated in PGCs. Keywords: single cell analysis, time course, Blimp1 knocked out Embryo isolation, dissection, and single cell cDNA amplification were performed as described (Kurimot et al., 2006, Nucleic Acids Res 34: e42; Kurimoto et al., 2007, Nature protocols, 2007, 2:739-52). Randomly picked cells were screened with gene-specific primers for Blimp1 and fragilis to select Blimp1-positive embryonic cells (which marks lineage-restricted PGC precursors or PGCs). For Blimp1 KO embryos, non-functional transcript from the Blimp1null allele was detected with the same primer set.