Molecular Medicine Israel

Direct Induction of the Three Pre-implantation Blastocyst Cell Types from Fibroblasts

Highlights

Gata3, Eomes, Tfap2c, Myc, and Esrrb convert fibroblasts into iPSCs, iTSCs, and iXENs

Esrrb, but not other pluripotency genes, can shift the TSC fate into pluripotency

Esrrb induces pluripotency by the activation of a unique XEN-like state

The interplay between Eomes and Esrrb determines cell fate decision
Summary
Following fertilization, totipotent cells undergo asymmetric cell divisions, resulting in three distinct cell types in the late pre-implantation blastocyst: epiblast (Epi), primitive endoderm (PrE), and trophectoderm (TE). Here, we aim to understand whether these three cell types can be induced from fibroblasts by one combination of transcription factors. By utilizing a sophisticated fluorescent knockin reporter system, we identified a combination of five transcription factors, Gata3, Eomes, Tfap2c, Myc, and Esrrb, that can reprogram fibroblasts into induced pluripotent stem cells (iPSCs), induced trophoblast stem cells (iTSCs), and induced extraembryonic endoderm stem cells (iXENs) , concomitantly. In-depth transcriptomic, chromatin, and epigenetic analyses provide insights into the molecular mechanisms that underlie the reprogramming process toward the three cell types. Mechanistically, we show that the interplay between Esrrb and Eomes during the reprogramming process determines cell fate, where high levels of Esrrb induce a XEN-like state that drives pluripotency and high levels of Eomes drive trophectodermal fate.

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