Schöler, Singhal

Project Title: Identification of additional/alternative factors required for cellular reprogramming

The generation of induced pluripotent stem (iPS) cells mediated by the transcription factor quartet of Oct4, Sox2, Klf4, and c-Myc occurs with extremely low efficiency. The use of a secondary reprogramming system improves efficiency to only ~4.5%, but the reprogramming process still requires a long duration of ~2-3 weeks for completion, despite all cells having an identical number of copies and integration sites of the transgenes. In an effort to further improve the reprogramming process, we have established a functional proteomics-based screening assay to identify reprogramming factors that can mediate reprogramming with higher efficiency and shorter duration. Using this assay, we identified components of the chromatin-remodeling complex BAF, namely Brg1 (Smarca4) and Baf155 (Smarcc1), that increase the efficiency of reprogramming, regardless of the presence or absence of c-Myc. Although these BAF complex chromatin remodeling components increase reprogramming efficiency, we discovered that they act at the intermediate stage of reprogramming. Here we propose to identify additional or alternative reprogramming factors by utilizing our previously established functional proteomics-screening assay, which will not only enhance both the efficiency and kinetics of the reprogramming process, but also help uncover the molecular mechanism underlying reprogramming.