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.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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Basic Helix-Loop-Helix Transcription Factors / genetics
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Basic Helix-Loop-Helix Transcription Factors / metabolism*
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Cell Differentiation / drug effects*
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Cell Line
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Cell Proliferation / drug effects
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Dose-Response Relationship, Drug
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Embryonic Stem Cells / drug effects*
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Embryonic Stem Cells / enzymology
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Gene Expression Regulation, Developmental / drug effects
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Gene Regulatory Networks / drug effects
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Glycogen Synthase Kinase 3 / antagonists & inhibitors*
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Glycogen Synthase Kinase 3 / genetics
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Glycogen Synthase Kinase 3 / metabolism
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Glycogen Synthase Kinase 3 beta
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Mice
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Pluripotent Stem Cells / drug effects*
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Pluripotent Stem Cells / enzymology
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Protein Kinase Inhibitors / pharmacology*
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RNA Interference
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Recombinant Fusion Proteins / metabolism
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Transfection
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beta Catenin / genetics
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beta Catenin / metabolism
Substances
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Basic Helix-Loop-Helix Transcription Factors
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CTNNB1 protein, mouse
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Protein Kinase Inhibitors
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Recombinant Fusion Proteins
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Tcf3 protein, mouse
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beta Catenin
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Glycogen Synthase Kinase 3 beta
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Glycogen Synthase Kinase 3
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glycogen synthase kinase 3 alpha