title: Retinoic acid directs neuronal differentiation of human pluripotent stem cell lines in a non-cell-autonomous manner.
abstract: Differentiation of human embryonic stem (ES) cells and embryonal carcinoma (EC) cells provides an in vitro model to study the process of neuronal differentiation. Retinoic acid (RA) is frequently used to promote neural differentiation of pluripotent cells under a wide variety of culture conditions. Through systematic comparison of differentiation conditions we demonstrate that RA induced neuronal differentiation of human ES and EC cells requires prolonged RA exposure and intercellular communication mediated by high cell density. These parameters are necessary for the up-regulation of neural gene expression (SOX2, PAX6 and NeuroD1) and the eventual appearance of neurons. Forced over-expression of neither SOX2 nor NEUROD1 was sufficient to overcome the density dependency of neuronal differentiation. Furthermore, inhibition of GSK3beta activity blocked the ability of RA to direct cell differentiation along the neural lineage, suggesting a role for appropriately regulated WNT signalling. These data indicate that RA mediated neuronal differentiation of human EC and ES cell lines is not a cell autonomous program but comprises of a multi-staged program that requires intercellular input.
authors.affiliation: Centre for Stem Cell Biology, Department of Biomedical Science, University of Sheffield, Sheffield, UK. tonge@lunenfeld.ca
authors.forename: Peter D
authors.initials: PD
authors.lastname: Tonge
authors.forename: Peter W
authors.initials: PW
authors.lastname: Andrews
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology; D015153:Blotting, Western; D018236:Carcinoma, Embryonal / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology*; D002453:Cell Cycle; D002454:Cell Differentiation / Q000187:drug effects*; D049109:Cell Proliferation; D054278:Embryonal Carcinoma Stem Cells / Q000187:drug effects* / Q000378:metabolism; D005434:Flow Cytometry; D005455:Fluorescent Antibody Technique; D006801:Humans; D009474:Neurons / Q000166:cytology* / Q000187:drug effects* / Q000378:metabolism; D039904:Pluripotent Stem Cells / Q000187:drug effects* / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D014212:Tretinoin / Q000494:pharmacology*
chemical_list: D000970:Antineoplastic Agents; D012333:RNA, Messenger; D014212:Tretinoin