Molecular Characterization of Down Syndrome Embryonic Stem Cells Reveals a Role for RUNX1 in Neural Differentiation

Down syndrome (DS) is the leading genetic cause of mental retardation and is caused by a third copy of human chromosome 21. The different pathologies of DS involve many tissues with a distinct array of neural phenotypes. Here we characterize new embryonic stem cell lines with DS (DS-ESCs), and focus on the neural aspects of the diease. Our results show that neural progenitor cells (NPCs) differentiated from five independent DS-ESC lines display increased apoptosis and down-regulation of forehead developmental genes. Analysis of differentially expressed genes suggested RUNX1 as a key transcription regulator in DS-NPCs. Using genome editing we were able to disrupt all three copies of RUNX1 in DS-ESCs, leading to down-regulation of several RUNX1 target developmental genes accompanied by reduced apoptosis and neuron migration. Our work sheds new light on the role of RUNX1 and the importance of dosage balance in the development of neural phenotypes in DS. Gene expression analysis was performed on a total of 3 human cell lines, including Down syndrome neural progenitor cells and genome edited Down syndrome neural progenitor cells