Transient RUNX1 Expression during Early Mesendodermal Differentiation ofhESCs Promotes Epithelial to Mesenchymal Transition through TGFB2 Signaling.

Jennifer J Vanoudenhove,Prachi N Ghule,Ricardo Medina,Jane B Lian,Sayyed K Zaidi,Gary S Stein,Janet L Stein

doi:10.1016/j.stemcr.2016.09.006

Jennifer J Vanoudenhove, Prachi N Ghule + Show 5 more

Open Access

https://doi.org/10.1016/j.stemcr.2016.09.006

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Abstract

SummaryThe transition of human embryonic stem cells (hESCs) from pluripotency to lineage commitment is not fully understood, and a role for phenotypic transcription factors in the initial stages of hESC differentiation remains to be explored. From a screen of candidate factors, we found that RUNX1 is selectively and transiently upregulated early in hESC differentiation to mesendodermal lineages. Transcriptome profiling and functional analyses upon RUNX1 depletion established a role for RUNX1 in promoting cell motility. In parallel, we discovered a loss of repression for several epithelial genes, indicating that loss of RUNX1 impaired an epithelial to mesenchymal transition during differentiation. Cell biological and biochemical approaches revealed that RUNX1 depletion specifically compromised TGFB2 signaling. Both the decrease in motility and deregulated epithelial marker expression upon RUNX1 depletion were rescued by reintroduction of TGFB2, but not TGFB1. These findings identify roles for RUNX1-TGFB2 signaling in early events of mesendodermal lineage commitment.

Highlights

Human embryonic stem cells have unlimited replicative potential and are capable of differentiating into cell types from each of the three germ layers (Thomson et al, 1998)
We discovered that the RUNX1b isoform was the predominantly expressed transcript in two different Human embryonic stem cells (hESCs) lines, the female H9 and male H1, during mesendodermal differentiation (Figure 1D)
Our results show that RUNX1 selectively occupies the transforming growth factor b2 (TGFB2), but not the TGFB1, promoter (Figure 4C), which is consistent with the effect of RUNX1 depletion on TGFB2 expression (Figure 4B)

Summary

Introduction

Human embryonic stem cells (hESCs) have unlimited replicative potential and are capable of differentiating into cell types from each of the three germ layers (Thomson et al, 1998). While much is known about the maintenance of pluripotency (Boward et al, 2016; Boyer et al, 2005; Chambers et al, 2003; Huang et al, 2015; Kapinas et al, 2013), how differentiation signals regulate the dissolution of pluripotency and the establishment of phenotype is not well understood. Once a differentiation signal has been introduced, early factors are expressed that prime the gene expression program of cells for lineage acquisition (Zaret and Carroll, 2011). We investigated whether phenotype-associated transcription factors may play an initial role in differentiation prior to their established function in specifying lineage identity. A candidate screen of phenotypic transcription factors identified RUNX1 as selectively and transiently upregulated as early as 8 hr during mesendodermal differentiation of hESCs

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Discussion

Conclusion