title: Inhibition of glycogen synthase kinase-3 alleviates Tcf3 repression of the pluripotency network and increases embryonic stem cell resistance to differentiation.
abstract: Self-renewal of rodent embryonic stem cells is enhanced by partial inhibition of glycogen synthase kinase-3 (Gsk3; refs 1, 2). This effect has variously been attributed to stimulation of Wnt signalling by β-catenin, stabilization of Myc protein and global de-inhibition of anabolic processes. Here we demonstrate that β-catenin is not necessary for embryonic stem cell identity or expansion, but its absence eliminates the self-renewal response to Gsk3 inhibition. Responsiveness is fully restored by truncated β-catenin lacking the carboxy-terminal transactivation domain. However, requirement for Gsk3 inhibition is dictated by expression of T-cell factor 3 (Tcf3) and mediated by direct interaction with β-catenin. Tcf3 localizes to many pluripotency genes in embryonic stem cells. Our findings confirm that Tcf3 acts as a transcriptional repressor and reveal that β-catenin directly abrogates Tcf3 function. We conclude that Gsk3 inhibition stabilizes the embryonic stem cell state primarily by reducing repressive influence on the core pluripotency network.
authors.affiliation: Wellcome Trust Centre for Stem Cell Research & Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QR, UK.
authors.forename: Jason
authors.initials: J
authors.lastname: Wray
authors.forename: Tüzer
authors.initials: T
authors.lastname: Kalkan
authors.forename: Sandra
authors.initials: S
authors.lastname: Gomez-Lopez
authors.forename: Dominik
authors.initials: D
authors.lastname: Eckardt
authors.forename: Andrew
authors.initials: A
authors.lastname: Cook
authors.forename: Rolf
authors.initials: R
authors.lastname: Kemler
authors.forename: Austin
authors.initials: A
authors.lastname: Smith
mesh_terms: D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics / Q000378:metabolism*; D002454:Cell Differentiation / Q000187:drug effects*; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D053595:Embryonic Stem Cells / Q000187:drug effects* / Q000201:enzymology; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D053263:Gene Regulatory Networks / Q000187:drug effects; D038362:Glycogen Synthase Kinase 3 / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D000071679:Glycogen Synthase Kinase 3 beta; D051379:Mice; D039904:Pluripotent Stem Cells / Q000187:drug effects* / Q000201:enzymology; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D034622:RNA Interference; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D014162:Transfection; D051176:beta Catenin / Q000235:genetics / Q000378:metabolism
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D038362:Glycogen Synthase Kinase 3; D000071679:Glycogen Synthase Kinase 3 beta; D047428:Protein Kinase Inhibitors; D011993:Recombinant Fusion Proteins; D051176:beta Catenin; C495267:CTNNB1 protein, mouse; C075668:Tcf3 protein, mouse; C448021:glycogen synthase kinase 3 alpha