The Transcription Factor TCFAP2C/AP-2γ Cooperates with CDX2 To Maintain Trophectoderm Formation

Abstract

In mammals, cell lineage specification is established at the blastocyst stage. At this stage, transcription factor Cdx2 represses pluripotency genes, thus promoting extraembryonic trophoblast fate. Recently, transcription factor Gata3 was shown to act in a parallel pathway in promoting trophoblast cell fate, suggesting that there are more factors working in the trophoblast lineage. Here, we report that the transcription factor Tcfap2c is expressed at a high level in the trophectoderm and is able to induce trophoblast fate in embryonic stem cells. Trophoblast fate induced by Tcfap2c does not require Cdx2 and vice versa, suggesting that the molecules act in alternative pathways. However, both Tcfap2c and Cdx2 are required for the upregulation of Elf5, a marker of trophoblast stem cell maintenance, suggesting that both factors are required for stable trophoblast induction. Tcfap2c-induced trophoblast-like cells are stable in long-term culture, indicating that they are capable of self-renewal. Tcfap2c-controlled trophoblast maintenance involves the induction of Cdx2 and the repression of the pluripotency factor Nanog. Tcfap2c-induced trophoblast-like cells differentiate to trophoblast derivatives in vitro and contribute to the trophectoderm in blastocysts in vivo. Taken together, these observations suggest that Tcfap2c and Cdx2 cooperate to override the pluripotency program and establish the extraembryonic trophoblast maintenance program in murine embryos.The earliest cell fate decision during mammalian development is the establishment of the first two cell lineages of the blastocyst prior to implantation. The inner cell mass (ICM) forms the embryo proper as well as extraembryonic endodermal components of the placenta, whereas the trophectoderm (TE) gives rise to the fetal portion of the placenta, a structure unique to mammalian development (11). Self-renewing embryonic stem cell (ESC) and trophoblast stem cell (TSC) lines have been derived from each of these lineages in vitro (10,23,36). TSCs exhibit the potential to differentiate into multiple trophoblastic cell types in vitro, participate in the normal development of chimeras, and contribute exclusively to the trophoblastic component of the placenta in vivo (28,36).At the genetic level, key factors that establish and maintain the TE lineage in the early embryo have been identified. Based on so far unknown positional information, the Hippo signaling pathway component YAP (Yes kinase-associated protein 1, a coactivator of Tead4) is phosphorylated by LATS (large tumor suppressor, a Ser/Thr kinase that belongs to the Ndr/LATS subfamily of protein kinase A/PKG/PKC kinases) and becomes cytoplasmic in the inner cells of the morula. In outer blastomeres, YAP remains in the nucleus and associates with and activates TEAD4 (26), which in turn transactivates the expression of the transcription factor CDX2 (caudal-related homeobox 2) (27, 40). CDX2 represses pluripotency markers such as Oct3/4 (Pou5f1) and Nanog (and vice versa), which leads to the maintenance of the restrict...

Elf5-centered transcription factor hub controls trophoblast stem cell self-renewal and differentiation through stoichiometry-sensitive shifts in target gene networks

“…These studies have revealed a number of TFs that are essential to establish and maintain TSCs, including Eomes, Elf5, and Tfap2c (Russ et al 2000;Donnison et al 2005;Kuckenberg et al 2010). Here, we show that these same three TFs physically bind to each other to form multimeric TF complexes and co-occupy trophoblast genes, including themselves, driving their expression.…”

“…For instance, Cdx2 and Elf5 are coexpressed in TSCs, but, upon induction of differentiation, Cdx2 is down-regulated more rapidly than Elf5 (Ng et al 2008). Similarly in vivo, Cdx2 and Eomes are restricted to a narrow region of the ExE immediately overlying the epiblast, whereas Elf5 and Tfap2c have a much broader expression domain extending into the proximal ExE and ectoplacental cone (EPC) (Auman et al 2002;Ng et al 2008;Ralston and Rossant 2008;Kuckenberg et al 2010;Adachi et al 2013). These data point to a seeming discrepancy: Although core TFs are coexpressed and can mutually activate each other in the TSC compartment, their expression domains become divergent with the onset of differentiation.…”

Nuclear–cytoplasmic incompatibility and inefficient development of pig–mouse cytoplasmic hybrid embryos

“…At this stage, Tead4 activates the expression of the transcription factors Cdx2 and Gata3 that are required for the establishment of a functional TE (Yagi et al 2007, Nishioka et al 2008, Home et al 2009, Ralston et al 2010. Cdx2 activates Gata3 and transcription factor Tcfap2c (and vice versa), which in turn represses the pluripotency genes, Nanog and/or Pou5f1 expression, leading to lineage restricted gene expression profiles (Niwa et al 2005, Home et al 2009, Kuckenberg et al 2010. Poor expression of all the above genes in cytoplasmic hybrids may have adversely affected ICM and TE lineage segregation.…”

AP2γ regulates neural and epidermal development downstream of the BMP pathway at early stages of ectodermal patterning

“…AP2γ is expressed in the inner cell mass (ICM) and trophectoderm of mouse embryo [32,47], and previous studies have focused on its functions in extraembryonic development. However, the functions of AP2γ during development from ICM to neural/epidermal ectoderm are not fully understood.…”

“…AP2α also regulates neural border specification during the neuralization stage in Xenopus and lamprey [30,31]. Mouse AP2γ is expressed in both extraembryonic and embryonic tissues [32,33] and displays multiple functions in extraembryonic development, neural crest induction and terminal epidermal differentiation [26,34,35]. Moreover, disruption of AP2γ leads to mouse embryonic lethality at approximately E7.…”