title: A GSK3-binding peptide from FRAT1 selectively inhibits the GSK3-catalysed phosphorylation of axin and beta-catenin.
abstract: The Axin-dependent phosphorylation of beta-catenin catalysed by glycogen synthase kinase-3 (GSK3) is inhibited during embryogenesis. This protects beta-catenin against ubiquitin-dependent proteolysis, leading to its accumulation in the nucleus, where it controls the expression of genes important for development. Frequently rearranged in advanced T-cell lymphomas 1 (FRAT1) is a mammalian homologue of a GSK3-binding protein (GBP), which appears to play a key role in the correct establishment of the dorsal-ventral axis in Xenopus laevis. Here, we demonstrate that FRATtide (a peptide corresponding to residues 188-226 of FRAT1) binds to GSK3 and prevents GSK3 from interacting with Axin. FRATtide also blocks the GSK3-catalysed phosphorylation of Axin and beta-catenin, suggesting a potential mechanism by which GBP could trigger axis formation. In contrast, FRATtide does not suppress GSK3 activity towards other substrates, such as glycogen synthase and eIF2B, whose phosphorylation is independent of Axin but dependent on a 'priming' phosphorylation. This may explain how the essential cellular functions of GSK3 can continue, despite the suppression of beta-catenin phosphorylation.
authors.affiliation: MRC Protein Phosphorylation Unit, MSI/WTB Complex, University of Dundee, UK.
authors.forename: G M
authors.initials: GM
authors.lastname: Thomas
authors.forename: S
authors.initials: S
authors.lastname: Frame
authors.forename: M
authors.initials: M
authors.lastname: Goedert
authors.forename: I
authors.initials: I
authors.lastname: Nathke
authors.forename: P
authors.initials: P
authors.lastname: Polakis
authors.forename: P
authors.initials: P
authors.lastname: Cohen
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D000818:Animals; D060466:Axin Protein; D001667:Binding, Competitive; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism* / Q000502:physiology; D002352:Carrier Proteins / Q000378:metabolism*; D002384:Catalysis; D002460:Cell Line; D003598:Cytoskeletal Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D005314:Embryonic and Fetal Development / Q000502:physiology; D004791:Enzyme Inhibitors / Q000378:metabolism*; D038362:Glycogen Synthase Kinase 3; D038341:Glycogen Synthase Kinases; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D008969:Molecular Sequence Data; D009363:Neoplasm Proteins; D010446:Peptide Fragments / Q000378:metabolism*; D010766:Phosphorylation; D011506:Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D012097:Repressor Proteins; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction / Q000502:physiology; D015534:Trans-Activators; D029867:Xenopus Proteins; D051176:beta Catenin
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D060466:Axin Protein; C495270:CTNNB1 protein, human; D002352:Carrier Proteins; D003598:Cytoskeletal Proteins; D004791:Enzyme Inhibitors; C491819:FRAT1 protein, human; D047908:Intracellular Signaling Peptides and Proteins; D009363:Neoplasm Proteins; D010446:Peptide Fragments; D011506:Proteins; D011518:Proto-Oncogene Proteins; D012097:Repressor Proteins; D015534:Trans-Activators; D029867:Xenopus Proteins; C555454:axin1 protein, Xenopus; D051176:beta Catenin; D038341:Glycogen Synthase Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D038362:Glycogen Synthase Kinase 3