Selective de-repression of germ cell-specific genes in mouse embryonic fibroblasts in a permissive epigenetic environment

Epigenetic modifications play crucial roles on establishment of tissue-specific transcription profiles and cellular characteristics. Direct conversions of fibroblasts into differentiated tissue cells by over-expression of critical transcription factors have been reported, but the epigenetic mechanisms underlying these conversions are still not fully understood. In addition, conversion of somatic cells into germ cells has not yet been achieved. To understand epigenetic mechanisms that underlie germ cell characteristics, we attempted to use defined epigenetic factors to directly convert mouse embryonic fibroblasts (MEFs) into germ cells. Here, we successfully induced germ cell-specific genes by inhibiting repressive epigenetic modifications via RNAi or small-molecule compounds. Under these conditions, some tissue-specific genes and stimulus-inducible genes were also induced. Meanwhile, the treatments did not result in genome-wide transcriptional activation. These results suggested that a permissive epigenetic environment resulted in selective de-repression of stimulus- and differentiation-inducible genes including germ cell-specific genes in MEFs. Total RNA (100 ng) from each sample was analyzed. Samples were prepared using the Agilent Low Input Quick Amp Labeling Kit; probes were hybridized onto the Agilent Whole Mouse Genome Oligo DNA Microarray kit Ver 2.0 (Agilent) according to the manufacturer’s instructions. The microarrays were scanned using the Agilent DNA microarray scanner (Agilent). Each cell-type was analyzed in three biological replicate.