Pluto Bioinformatics

GSE99202: YAP Repression of the WNT3 Gene Controls hESC Differentiation Along the Cardiac Mesoderm Lineage

Bulk RNA sequencing

In hESCs, Wnt3/-catenin activity is low and Activin/SMAD signaling ensures NANOG expression to sustain pluripotency. In response to exogenous Wnt3 effectors, Activin/SMADs switch to cooperate with -catenin and induce mesendodermal differentiation genes. We show here that the HIPPO effector YAP binds to the WNT3 gene enhancer and prevents the gene from being induced by Activin in proliferating hESCs. In the absence of YAP, Activin signaling is sufficient to induce expression of the endogenous Wnt3 cytokine, which stabilizes -catenin and selectively activates genes required for cardiac mesoderm (ME) formation. Interestingly, Activin-stimulated YAP-knockout hESCs strongly express -catenin-dependent cardiac mesoderm markers (BAF60c and HAND1), but unlike WT hESCs, fail to express cardiac inhibitor genes (CDX2, MSX1). Accordingly, YAP-/- cells treated with Activin alone can differentiate efficiently to beating cardiomyocytes in culture, bypassing the need for sequential treatment with exogenous Wnt ligand and Wnt inhibitors. Similarly, Activin in combination with small-molecule YAP inhibitors generates beating cardiomyocytes from wild-type hESCs following a one- step protocol. Our findings highlight an unanticipated role of YAP as an upstream regulator of WNT3 to maintain hESC pluripotency in the presence of Activin, and uncover a direct route for the development of human embryonic cardiac mesoderm. SOURCE: Ling Huang (lhuang@salk.edu) - The Salk Institute