Expression data from OSKM-mediated 2nd reprogramming cells and the corresponding iPS cell line

Forced expression of four transcription factors Oct4,Sox2, Klf4 and Myc (OSKM) induces somatic cell reprogramming towards pluripotency. Major efforts have been made to characterize the molecular events involved in this process. Yet, it remains elusive how gene expression change, epigenetic landscape remodelling and cell fate conversion are triggered by expression of these Yamanaka factors. To address this gap, we utilized a secondary inducible reprogramming system and performed genome-wide profilings of Oct4 binding, histone modification (H3K4me3/H3K27me3/H3K4me1/H3K27ac), and gene expression analysis during this process. Through integrative analysis, we revealed stage-specific Oct4 binding and enhancer signatures in consistence with gene expression changes, in which the initial regression of somatic program is followed by the gradual acquisition of pluripotent program. Oct4 preferatially binds to H3K4me1 marked enhancer regions and Oct4 binding is positively correlated with active mark H3K27ac. Moreover, we observed significant enhancer activation of epigenetic related genes, especially acetylation associated genes, prior to pluripotency network activation, suggesting a pivotal role of epigenetic remodelling in the process of pluripotency acquisition and maintenance. We used microarrays to explore the global changes of gene expression during OSKM-mediated somatic cell reprogramming. time series design with bulk population samples collected at different time point of 2nd reprogramming as well as a corresponding iPS cell line. Each sample include two replicates. 2nd mouse embryonic fibroblasts(sample day0) were treated with ES medium supplemented with 1µg/ml Doxcycline and 50µg/ml Vitamin C for 15 days (sample day1-day15); 72 hours after dox and Vc withdrawl, dox-independent iPS cells are collected(sample day18).