BRACHYURY and CDX2 Mediate BMP-Induced Differentiation of Human and Mouse Pluripotent Stem Cells into Embryonic and Extraembryonic Lineages

Abstract

SummaryBMP is thought to induce hESC differentiation toward multiple lineages including mesoderm and trophoblast. The BMP-induced trophoblast phenotype is a long-standing paradox in stem cell biology. Here we readdressed BMP function in hESCs and mouse epiblast-derived cells. We found that BMP4 cooperates with FGF2 (via ERK) to induce mesoderm and to inhibit endoderm differentiation. These conditions induced cells with high levels of BRACHYURY (BRA) that coexpressed CDX2. BRA was necessary for and preceded CDX2 expression; both genes were essential for expression not only of mesodermal genes but also of trophoblast-associated genes. Maximal expression of the latter was seen in the absence of FGF but these cells coexpressed mesodermal genes and moreover they differed in cell surface and epigenetic properties from placental trophoblast. We conclude that BMP induces human and mouse pluripotent stem cells primarily to form mesoderm, rather than trophoblast, acting through BRA and CDX2.

Cdx2Efficiently Induces Trophoblast Stem-Like Cells in Naïve, but Not Primed, Pluripotent Stem Cells

“…Our model is also consistent with prior observations that EpiSCs are resistant to forming trophoblast following growth factor treatment [53]. Notably, multiple pluripotent states exist within EpiSCs [13,54], with some lines more primed for mesendodermal differentiation than others [13].…”

MSX2 mediates entry of human pluripotent stem cells into mesendoderm by simultaneously suppressing SOX2 and activating NODAL signaling

“…As expected, stimulation of hESCs with BMP4 led to a rapid and dramatic upregulation of MSX2 mRNA within 3 h of BMP4 stimulation ( Figure 3A and Supplementary information, Figure S4C). Furthermore, induction of MSX2 expression consistently preceded T and CDX2 -two previously reported BMP4 targets in hESCs [48] ( Figure 3A and Supplementary information, Figure S4C). In contrast, treatment of cells with Activin A, Wnt3a, bFGF and other factors caused little effect on MSX2 and MSX1 expression ( Figure 3B).…”

“…Despite these critical functions, the direct target genes of BMP signaling that mediate mesendoderm differentiation remain elusive in hPSCs. In this study, npg www.cell-research.com | Cell Research we show that expression of MSX2 is induced within 3 h after the addition of BMP4, much more early than T and CDX2, two previously reported downstream effectors of BMP signaling in hESCs [48]. We show that Smad1 can bind to the phylogenetically conserved BMP-responsive region within the MSX2 promoter in hESCs.…”

Notch signaling represses p63 expression in the developing surface ectoderm

“…2C; supplementary material Fig. S10A,B), indicative of mesoderm (Bernando et al, 2011) or trophectoderm (Xu et al, 2002) specification. Taken together these results suggest that this differentiation protocol generates primarily ectodermal cells, including epidermal keratinocyte progenitor cells.…”