Stepwise Clearance of Repressive Roadblocks Drives Cardiac Induction in Human ESCs

• Published in: Cell stem cell 2016-03, Vol.18 (3), p.341-353
• Main Authors: Rao, Jyoti, Pfeiffer, Martin J., Frank, Stefan, Adachi, Kenjiro, Piccini, Ilaria, Quaranta, Roberto, Araúzo-Bravo, Marcos, Schwarz, Juliane, Schade, Dennis, Leidel, Sebastian, Schöler, Hans R., Seebohm, Guiscard, Greber, Boris
• Format: Article
• Language: English
• Subjects: CDX2 Transcription Factor - genetics; CDX2 Transcription Factor - metabolism; Cell Differentiation; Cell Line; Homeodomain Proteins - genetics; Homeodomain Proteins - metabolism; Human Embryonic Stem Cells - cytology; Human Embryonic Stem Cells - metabolism; Humans; MicroRNAs - genetics; MicroRNAs - metabolism; MSX1 Transcription Factor - genetics; MSX1 Transcription Factor - metabolism; Myocytes, Cardiac - cytology; Myocytes, Cardiac - metabolism; SOXB1 Transcription Factors - genetics; SOXB1 Transcription Factors - metabolism; T-Box Domain Proteins - genetics; T-Box Domain Proteins - metabolism; Wnt Signaling Pathway
• ISSN: 1934-5909; 1875-9777
• DOI: 10.1016/j.stem.2015.11.019

Cardiac induction requires stepwise integration of BMP and WNT pathway activity. Human embryonic stem cells (hESCs) are developmentally and clinically relevant for studying the poorly understood molecular mechanisms downstream of these cascades. We show that BMP and WNT signaling drive cardiac specification by removing sequential roadblocks that otherwise redirect hESC differentiation toward competing fates, rather than activating a cardiac program per se. First, BMP and WNT signals pattern mesendoderm through cooperative repression of SOX2, a potent mesoderm antagonist. BMP signaling promotes miRNA-877 maturation to induce SOX2 mRNA degradation, while WNT-driven EOMES induction transcriptionally represses SOX2. Following mesoderm formation, cardiac differentiation requires inhibition of WNT activity. We found that WNT inhibition serves to restrict expression of anti-cardiac regulators MSX1 and CDX2/1. Conversely, their simultaneous disruption partially abrogates the requirement for WNT inactivation. These results suggest that human cardiac induction depends on multi-stage repression of alternate lineages, with implications for deriving expandable cardiac stem cells. [Display omitted] •BMP/WNT ligand gradients pattern diverse mesendodermal fates in hESCs•BMP and WNT cooperatively repress SOX2 to clear mesoderm formation blockage•Inhibition of WNT signaling in hESC-derived mesoderm represses cardiac antagonists In this article, Greber and colleagues reveal signaling principles that underlie directed differentiation of human ESCs into cardiomyocytes. The authors show that BMP and WNT pathways promote cardiac induction through sequential and dose-dependent suppression of repressive regulators that otherwise drive differentiation into alternate lineages.