title: Cell Fate Specification Based on Tristability in the Inner Cell Mass of Mouse Blastocysts.
abstract: During development, interactions between transcription factors control the specification of different cell fates. The regulatory networks of genetic interactions often exhibit multiple stable steady states; such multistability provides a common dynamical basis for differentiation. During early murine embryogenesis, cells from the inner cell mass (ICM) can be specified in epiblast (Epi) or primitive endoderm (PrE). Besides the intracellular gene regulatory network, specification is also controlled by intercellular interactions involving Erk signaling through extracellular Fgf4. We previously proposed a model that describes the gene regulatory network and its interaction with Erk signaling in ICM cells. The model displays tristability in a range of Fgf4 concentrations and accounts for the self-organized specification process observed in vivo. Here, we further investigate the origin of tristability in the model and analyze in more detail the specification process by resorting to a simplified two-cell model. We also carry out simulations of a population of 25 cells under various experimental conditions to compare their outcome with that of mutant embryos or of embryos submitted to exogenous treatments that interfere with Fgf signaling. The results are analyzed by means of bifurcation diagrams. Finally, the model predicts that heterogeneities in extracellular Fgf4 concentration play a primary role in the spatial arrangement of the Epi/PrE cells in a salt-and-pepper pattern. If, instead of heterogeneities in extracellular Fgf4 concentration, internal fluctuations in the levels of expression of the transcription factors are considered as a source of randomness, simulations predict the occurrence of unrealistic switches between the Epi and the PrE cell fates, as well as the evolution of some cells toward one of these states without passing through the previous ICM state, in contrast to what is observed in vivo.
authors: Unité de Chronobiologie théorique, Faculté des Sciences, Université Libre de Bruxelles (ULB), Campus Plaine, Brussels, Belgium.
authors: Laurane
authors: L
authors: De Mot
authors: Unité de Chronobiologie théorique, Faculté des Sciences, Université Libre de Bruxelles (ULB), Campus Plaine, Brussels, Belgium.
authors: Didier
authors: D
authors: Gonze
authors: Laboratoire Génétique, Reproduction et Développement, Université Clermont Auvergne, Clermont-Ferrand, France; Institut National de la Santé et de la Recherche Médicale (INSERM), UMR1103, Clermont-Ferrand, France; Centre National de la Recherche Scientifique (CNRS), UMR6293, Clermont-Ferrand, France.
authors: Sylvain
authors: S
authors: Bessonnard
authors: Laboratoire Génétique, Reproduction et Développement, Université Clermont Auvergne, Clermont-Ferrand, France; Institut National de la Santé et de la Recherche Médicale (INSERM), UMR1103, Clermont-Ferrand, France; Centre National de la Recherche Scientifique (CNRS), UMR6293, Clermont-Ferrand, France.
authors: Claire
authors: C
authors: Chazaud
authors: Unité de Chronobiologie théorique, Faculté des Sciences, Université Libre de Bruxelles (ULB), Campus Plaine, Brussels, Belgium; Stellenbosch Institute for Advanced Study (STIAS), Wallenberg Research Centre at Stellenbosch University, Stellenbosch, South Africa.
authors: Albert
authors: A
authors: Goldbeter
authors: Unité de Chronobiologie théorique, Faculté des Sciences, Université Libre de Bruxelles (ULB), Campus Plaine, Brussels, Belgium. Electronic address: gdupont@ulb.ac.be.
authors: Geneviève
authors: G
authors: Dupont
mesh_terms: D000818:Animals; D001755:Blastocyst / Q000166:cytology*; D002454:Cell Differentiation; D051519:Fibroblast Growth Factor 4 / Q000378:metabolism; D005855:Germ Layers / Q000166:cytology; D020935:MAP Kinase Signaling System; D051379:Mice; D008962:Models, Theoretical
chemical_list: C496446:Fgf4 protein, mouse; D051519:Fibroblast Growth Factor 4