Lineage-Specific Profiling Delineates the Emergence and Progression of Naive Pluripotency in Mammalian Embryogenesis

Abstract

SummaryNaive pluripotency is manifest in the preimplantation mammalian embryo. Here we determine transcriptome dynamics of mouse development from the eight-cell stage to postimplantation using lineage-specific RNA sequencing. This method combines high sensitivity and reporter-based fate assignment to acquire the full spectrum of gene expression from discrete embryonic cell types. We define expression modules indicative of developmental state and temporal regulatory patterns marking the establishment and dissolution of naive pluripotency in vivo. Analysis of embryonic stem cells and diapaused embryos reveals near-complete conservation of the core transcriptional circuitry operative in the preimplantation epiblast. Comparison to inner cell masses of marmoset primate blastocysts identifies a similar complement of pluripotency factors but use of alternative signaling pathways. Embryo culture experiments further indicate that marmoset embryos utilize WNT signaling during early lineage segregation, unlike rodents. These findings support a conserved transcription factor foundation for naive pluripotency while revealing species-specific regulatory features of lineage segregation.

Esrrb extinction triggers dismantling of naïve pluripotency and marks commitment to differentiation

“…A coordinated downregulation of naïve pluripotency markers is reminiscent of the process occurring during the transition from pre‐ to post‐implantation development (Boroviak et al , 2014, 2015; Kojima et al , 2014). The period of loss of NANOG expression occurring at peri‐implantation (Chambers et al , 2003; Acampora et al , 2013) may enable cells of the epiblast to downregulate a number of pivotal naïve pluripotency determinants, including ESRRB (Adachi et al , 2013).…”

Lineage specification in the mouse preimplantation embryo

“…Fgf4 specifically labels EPI cells during blastocyst formation (Kurimoto et al, 2006;Guo et al, 2010;Frankenberg et al, 2011;Ohnishi et al, 2014) and is not expressed in Nanog mutants (Frankenberg et al, 2011). Fgfr2 is expressed in all early ICM cells at E3.25 before its restriction to PE cells by E3.5, suggesting that all early ICM cells are capable of responding to FGF ligands (Ohnishi et al, 2014;Boroviak et al, 2015). Blocking FGF signalling is sufficient for all ICM cells to adopt an EPI fate (Chazaud et al, 2006;Nichols et al, 2009;Yamanaka et al, 2010;Kang et al, 2013;Krawchuk et al, 2013), whereas the addition of excess FGF4 is sufficient to differentiate all ICM cells into PE .…”

“…BMP4 is expressed in the EPI of the early blastocyst (Coucouvanis and Martin, 1999;Guo et al, 2010;Graham et al, 2014;Boroviak et al, 2015). The overexpression of a dominantnegative form of BMPR2 in one blastomere at the 2-cell stage reduces the PE contribution of the progeny of this blastomere.…”

“…Nonetheless, it should be noted that the in vitro derivation of 'naïve' human ESCs that resemble early in vivo EPI cells often involves MEK1 (MAP2K1) inhibition (Manor et al, 2015), and thus the role of ERK signalling in vitro and in vivo is still unresolved. Interestingly, cooperation between FGF and Wnt pathways is required for PE formation in marmoset embryos (Boroviak et al, 2015). Therefore, the relative importance of these various signalling pathways could have evolved differently in diverse mammalian species to induce the same core lineage-specific transcriptional networks.…”

An overview of mammalian pluripotency

“…Recent advancements in single-cell analysis have provided insights into the molecular underpinnings of the pluripotent ICM/epiblast in humans. Several differences between human and mouse have been revealed by these studies, for example expression of Klf2 and Esrrb was only observed in mouse ICM, whereas KLF17 is likely to be a primate-specific pluripotency factor (Blakeley et al, 2015;Boroviak et al, 2015). Post-implantation epiblast development is essentially inaccessible in humans and the only known information is confined to morphological descriptions.…”