title: Regulation of developmental competence and commitment towards the definitive endoderm lineage in human embryonic stem cells.
abstract: Human embryonic stem cells (hESCs) can self-renew and become all three germ layers. Nodal/Activin signaling specifies developmental status in hESCs: moderate Nodal/Activin signaling maintains pluripotency, while enhancement and inhibition promote definitive endoderm (DE) and neuroectoderm (NE) development, respectively. However, how modulation of Nodal/Activin signaling influences developmental competence and commitment toward specific lineages is still unclear. Here, we showed that enhancement of Nodal/Activin signaling for 4 days was necessary and sufficient to upregulate DE markers, while it diminished the upregulation of NE markers by inhibition of Nodal/Activin signaling. This suggests that after 4 days of enhanced Nodal/Activin signaling, hESCs are committed to the DE lineage and have lost competence toward the NE lineage. In contrast, inhibition of Nodal/Activin signaling using LY364947 for 2 days was sufficient to impair competence toward the DE lineage, although cells were still able to activate LEFTY1 and NODAL, direct targets of Nodal/Activin signaling. Expression analyses indicated that the levels of pluripotency regulators NANOG and POU5F1 were significantly diminished by 2 days of LY364947 treatment, although the expression of NANOG, but not POU5F1, was restored immediately upon Activin A treatment. Thus, downregulation of POU5F1 coincided with the abrogation of DE competence caused by inhibition of Nodal/Activin signaling.
authors.affiliation: Institute for Biogenesis Research, University of Hawaii John A. Burns School of Medicine, Honolulu, Hawaii 96813, USA.
authors.forename: Kate Lynn
authors.initials: KL
authors.lastname: Jaremko
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Marikawa
mesh_terms: D028341:Activins / Q000378:metabolism / Q000494:pharmacology; D019070:Cell Lineage; D053595:Embryonic Stem Cells / Q000166:cytology* / Q000378:metabolism; D004707:Endoderm / Q000166:cytology* / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects; D018398:Homeodomain Proteins / Q000378:metabolism; D006801:Humans; D000071317:Nanog Homeobox Protein; D055457:Nodal Protein / Q000378:metabolism; D050814:Octamer Transcription Factor-3 / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D018398:Homeodomain Proteins; C486780:NANOG protein, human; D000071317:Nanog Homeobox Protein; D055457:Nodal Protein; D050814:Octamer Transcription Factor-3; C494173:POU5F1 protein, human; C422405:activin A; D028341:Activins