Temporal RNA-seq expression profiling of Sox17-medaited XEN conversion of ESCs

The transcription factor Sox17 is expressed in early primitive endoderm-fated cells of the mouse embryo and in embryo-derived extraembryonic endoderm (ExEn) stem (XEN) cells. We have shown that overexpression of Sox17 in mouse embryonic stem cells (ESCs) drives cell fate to a committed XEN-like cell state (Sox17-XEN cells). When placed back into the embryo, Sox17-XEN cells contribute exclusively to the ExEn. Transient Sox17 expression is sufficient to drive this fate change during which time cells transit through distinct intermediate states prior to the generation of functional XEN-like cells. We identified dynamic regulatory networks driving Sox17-mediated XEN conversion by analyzing a dynamic regulatory map of gene expression bifurcation points throughout conversion, created using RNA-seq time series data. We found that Sox17 orchestrates this conversion process by acting in autoregulatory and feed-forward network motifs, regulating dynamic gene regulatory networks (GRNs) directing cell fate. We have shown that Sox17-mediated XEN conversion provides a powerful tool for understanding the regulation of cell fate changes and for the elucidation of GRNs regulating lineage decisions in the mouse embryo. Overall design: Total RNA was extracted during a time course of Sox17 overexpression in mouse ESCs at 7 time points as well as from wild-type ESCs and wild-type XEN cells.