Genomic binding by an artificially evolved POU (ePOU)

We generated Oct4 libraries by randomizing selected amino acids and by recombining domains of paralogous POU family genes. These libraries were subjected to iterative rounds of pooled screens to select variants that enhance pluripotency induction. We identified an artificially evolved POU factor (ePOU) that substantially outperforms wild-type Oct4 in terms of mouse embryonic fibrobast (MEF) reprogramming. To probe whether the ePOU and Oct4 differentially engage the chromatin of reprogramming cells, we performed chromatin immunoprecipitation sequencing (ChIPseq) for both factors and Sox2. Two cocktails Oct4 (O), Sox2 (S), Klf4 (K), c-Myc (M) and ePOU/S/K/M were transduced into OG2 MEF cells which is MEF cells with Oct4 promotor. Genome binding profiles of Oct4, Sox2 and ePOU in reprogramming intermediate cells at day 3 of retrovirus system based somatic cell reprogramming were generated by deep sequencing, using Illumina Hiseq X Ten.