Fgf and Esrrb integrate epigenetic and transcriptional networks that regulate self-renewal of trophoblast stem cells

Abstract

Esrrb (oestrogen-related receptor beta) is a transcription factor implicated in embryonic stem (ES) cell self-renewal, yet its knockout causes intrauterine lethality due to defects in trophoblast development. Here we show that in trophoblast stem (TS) cells, Esrrb is a downstream target of fibroblast growth factor (Fgf) signalling and is critical to drive TS cell self-renewal. In contrast to its occupancy of pluripotency-associated loci in ES cells, Esrrb sustains the stemness of TS cells by direct binding and regulation of TS cell-specific transcription factors including Elf5 and Eomes. To elucidate the mechanisms whereby Esrrb controls the expression of its targets, we characterized its TS cell-specific interactome using mass spectrometry. Unlike in ES cells, Esrrb interacts in TS cells with the histone demethylase Lsd1 and with the RNA Polymerase II-associated Integrator complex. Our findings provide new insights into both the general and context-dependent wiring of transcription factor networks in stem cells by master transcription factors.

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

“…2A). Interestingly, we also identified several members of the Integrator complex, thus supporting a previous study suggesting that this complex may form a key part of the basal transcriptional machinery in TSCs (Latos et al 2015).…”

“…Our data showed that Elf5 associates with components of both activating (e.g., Bptf and Chd7) and repressive (Sin3 and Polycomb) chromatin complexes, indicating its role in both gene activation and repression. It is noteworthy that the Elf5 interactome did not include other critical TSC TFs such as Cdx2 or Esrrb, and we did not identify Elf5 associated with Cdx2 or Esrrb in the reciprocal interactomes (Latos et al 2015). Together with the minimal genomic binding overlap between Cdx2 and Elf5, it appears that these TFs function in mostly parallel circuits to maintain self-renewal of TSCs, except at retroviral elements where they have a joint function (Chuong et al 2013).…”

“…Immunoprecipitated proteins from three biological replicates each of Elf5 and vector transfected TSCs were analyzed as before (Webster and Oxley 2009;Latos et al 2015). Mass spectrometric data were processed using Proteome Discoverer version 1.4 (Thermo Scientific) and searched against the mouse entries in UniProt 2013.09 and a database of common contaminants using Mascot version 2.3 (Matrix Science), and the results were imported into Scaffold version 3.6 (Proteome Software, Inc.).…”

“…Genome-wide occupancy analyses of Cdx2, Elf5, Eomes, Ets2, Tfap2c, Gata3, Sox2, and Esrrb in TSCs revealed that they cobind a significant number of target loci, including themselves, to establish a self-reinforcing TSC-specific transcriptional network (Kidder and Palmer 2010;Adachi et al 2013;Chuong et al 2013;Latos et al 2015). However, despite coexpression in the TSC compartment in vivo and in vitro, the precise temporal and spatial expression domains of these various TFs are not fully overlapping.…”

“…A number of TFs are known to be involved in either the determination of trophoblast cell fate and/or the ability to derive or maintain TSCs. Among these are the TEA domain family member Tead4 (Yagi et al 2007;Nishioka et al 2008), the caudal-type homeobox factor Cdx2, the Tbox gene Eomes, the SRY-box gene Sox2, and the estrogen-related receptor Esrrb (Russ et al 2000;Tremblay et al 2001;Avilion et al 2003;Strumpf et al 2005;Ralston and Rossant 2008;Adachi et al 2013;Latos et al 2015). Other TFs important for the establishment of a self-renewing TSC population include the AP-2 family member Tfap2c (Auman et al 2002;Werling and Schorle 2002), the Ets family members Ets2 and Elf5 (Yamamoto et al 1998;Donnison et al 2005), and the Gata motif-containing factor Gata3 (Home et al 2009;Ralston et al 2010).…”