title: Differential response of epiblast stem cells to Nodal and Activin signalling: a paradigm of early endoderm development in the embryo.
abstract: Mouse epiblast stem cells (EpiSCs) display temporal differences in the upregulation of Mixl1 expression during the initial steps of in vitro differentiation, which can be correlated with their propensity for endoderm differentiation. EpiSCs that upregulated Mixl1 rapidly during differentiation responded robustly to both Activin A and Nodal in generating foregut endoderm and precursors of pancreatic and hepatic tissues. By contrast, EpiSCs that delayed Mixl1 upregulation responded less effectively to Nodal and showed an overall suboptimal outcome of directed differentiation. The enhancement in endoderm potency in Mixl1-early cells may be accounted for by a rapid exit from the progenitor state and the efficient response to the induction of differentiation by Nodal. EpiSCs that readily differentiate into the endoderm cells are marked by a distinctive expression fingerprint of transforming growth factor (TGF)-β signalling pathway genes and genes related to the endoderm lineage. Nodal appears to elicit responses that are associated with transition to a mesenchymal phenotype, whereas Activin A promotes gene expression associated with maintenance of an epithelial phenotype. We postulate that the formation of definitive endoderm (DE) in embryoid bodies follows a similar process to germ layer formation from the epiblast, requiring an initial de-epithelialization event and subsequent re-epithelialization. Our results show that priming EpiSCs with the appropriate form of TGF-β signalling at the formative phase of endoderm differentiation impacts on the further progression into mature DE-derived lineages, and that this is influenced by the initial characteristics of the cell population. Our study also highlights that Activin A, which is commonly used as an in vitro surrogate for Nodal in differentiation protocols, does not elicit the same downstream effects as Nodal, and therefore may not effectively mimic events that take place in the mouse embryo.
authors.affiliation: Embryology Unit, Children's Medical Research Institute, Westmead, New South Wales 2145, Australia.
authors.forename: Keren
authors.initials: K
authors.lastname: Kaufman-Francis
authors.affiliation: Embryology Unit, Children's Medical Research Institute, Westmead, New South Wales 2145, Australia.
authors.forename: Hwee Ngee
authors.initials: HN
authors.lastname: Goh
authors.affiliation: Embryology Unit, Children's Medical Research Institute, Westmead, New South Wales 2145, Australia Institute of Integrated Cell-Material Science, Kyoto University, Kyoto 606-8501, Japan.
authors.forename: Yoji
authors.initials: Y
authors.lastname: Kojima
authors.affiliation: Embryology Unit, Children's Medical Research Institute, Westmead, New South Wales 2145, Australia.
authors.forename: Joshua B
authors.initials: JB
authors.lastname: Studdert
authors.affiliation: Embryology Unit, Children's Medical Research Institute, Westmead, New South Wales 2145, Australia.
authors.forename: Vanessa
authors.initials: V
authors.lastname: Jones
authors.affiliation: Embryology Unit, Children's Medical Research Institute, Westmead, New South Wales 2145, Australia.
authors.forename: Melinda D
authors.initials: MD
authors.lastname: Power
authors.affiliation: Embryology Unit, Children's Medical Research Institute, Westmead, New South Wales 2145, Australia Bioinformatics Group, Children's Medical Research Institute, Westmead, New South Wales 2145, Australia.
authors.forename: Emilie
authors.initials: E
authors.lastname: Wilkie
authors.affiliation: Bioinformatics Group, Children's Medical Research Institute, Westmead, New South Wales 2145, Australia.
authors.forename: Erdahl
authors.initials: E
authors.lastname: Teber
authors.affiliation: Embryology Unit, Children's Medical Research Institute, Westmead, New South Wales 2145, Australia Sydney Medical School, University of Sydney, Sydney, New South Wales 2008, Australia.
authors.forename: David A F
authors.initials: DA
authors.lastname: Loebel
authors.affiliation: Embryology Unit, Children's Medical Research Institute, Westmead, New South Wales 2145, Australia Sydney Medical School, University of Sydney, Sydney, New South Wales 2008, Australia ptam@cmri.org.au.
authors.forename: Patrick P L
authors.initials: PP
authors.lastname: Tam
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000502:physiology*; D053595:Embryonic Stem Cells / Q000378:metabolism*; D004707:Endoderm / Q000166:cytology / Q000196:embryology*; D018507:Gene Expression Regulation, Developmental / Q000235:genetics / Q000502:physiology*; D005855:Germ Layers / Q000166:cytology / Q000196:embryology*; D018398:Homeodomain Proteins / Q000378:metabolism; D028322:Inhibin-beta Subunits / Q000378:metabolism*; D051379:Mice; D055457:Nodal Protein / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology; D016212:Transforming Growth Factor beta / Q000378:metabolism
chemical_list: D018398:Homeodomain Proteins; C464781:Mixl1 protein, mouse; D055457:Nodal Protein; C526008:Nodal protein, mouse; D016212:Transforming Growth Factor beta; C103008:inhibin beta A subunit; D028322:Inhibin-beta Subunits
keywords: TGF-β signalling; directed differentiation; endoderm differentiation; epiblast stem cells; gastrulation; lineage propensity