Switch Enhancer Elements Control Cell Fate in Human Embryonic Stem Cells (ChIP-Seq)

A small toolkit of morphogens is used repeatedly to direct development, raising the question of how context dictates interpretation of the same cue. One example is the TGFß pathway that in human embryonic stem cells fulfills two opposite functions: pluripotency maintenance and mesendoderm (ME) specification. Using proteomics coupled to analysis of genome occupancy, we uncover a regulatory complex comprised of transcriptional effectors of the Hippo pathway (TAZ/YAP/TEAD), the TGFß pathway (SMAD2/3) and the pluripotency regulator OCT4 (TSO). TSO collaborates with NuRD repressor complexes to buffer pluripotency gene expression, while suppressing ME genes. Importantly, the SMAD DNA binding partner FOXH1, a major specifier of ME, is found near TSO elements and upon fate specification we show that TSO is disrupted with subsequent SMAD-FOXH1 induction of ME. These studies define switch enhancer elements and provide a framework to understand how cellular context dictates interpretation of the same morphogen signal in development. Overall design: ChIP experiment, a total of 8 samples: 4 samples DMSO treated (Input ctr, IgG ctr, SMAD2 precipitation, TEAD4 precipitation), 4 samples SB431542 (Input ctr, IgG ctr, SMAD2 precipitation, TEAD4 precipitation)