title: Role of ERK 1/2 signaling in neuronal differentiation of cultured embryonic stem cells.
abstract: Embryonic stem (ES) cells represent an ideal source for cell engraftment in the damaged central nervous system (CNS). Understanding key signals that control ES cell differentiation may improve cell type-specific differentiation that is suitable for transplantation therapy. We tested the hypothesis that extracellular signal-regulated kinase (ERK) 1/2 phosphorylation is an early signaling event required for the neuronal differentiation of ES cells. Cultured mouse ES cells were treated with an all-trans-retinoic-acid (RA) protocol to generate neurally induced progenitor cells. Western blot analysis showed a dramatic increase in ERK 1/2 phosphorylation (p-ERK 1/2) 1-5 days after RA induction, which was attenuated in the presence of the p-ERK 1/2-specific inhibitor UO126. Phospho-ERK 1/2 inhibition significantly reduced the number of NeuN-positive cells and the expression of associated cytoskeletal proteins. In differentiating ES cells, there was increased nuclear translocation of STAT3 and decreased protein expression levels of GDNF, BDNF and NGF. STAT3 translocation was attenuated by UO126. Finally, caspase-3 activation was observed in the presence of UO126, suggesting that the ERK pathway also contributes to the survival of differentiating ES cells. These data indicate that ERK 1/2 phosphorylation is a key event required for early neuronal differentiation and survival of ES cells.
authors.affiliation: Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, South Carolina 29425, USA.
authors.forename: Zegui
authors.initials: Z
authors.lastname: Li
authors.forename: Michelle Hedrick
authors.initials: MH
authors.lastname: Theus
authors.forename: Ling
authors.initials: L
authors.lastname: Wei
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology*; D002460:Cell Line; D053595:Embryonic Stem Cells / Q000166:cytology / Q000502:physiology*; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000502:physiology*; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism*; D009474:Neurons / Q000166:cytology / Q000502:physiology*; D033581:Stem Cell Transplantation; D014212:Tretinoin / Q000494:pharmacology
chemical_list: D000970:Antineoplastic Agents; D014212:Tretinoin; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3