A novel role for glycogen synthase kinase-3 in Xenopus development: maintenance of oocyte cell cycle arrest by a beta-catenin-independent mechanism.
We have examined the expression of glycogen synthase kinase-3beta in oocytes and early embryos of Xenopus and found that the protein is developmentally regulated. In resting oocytes, GSK-3beta is active and it is inactivated on maturation in response to progesterone. GSK-3beta inactivation is necessary and rate limiting for the cell cycle response to this hormone and the subsequent accumulation of beta-catenin. Overexpression of a dominant negative form of the kinase accelerates maturation, as does inactivation by expression of Xenopus Dishevelled or microinjection of an inactivating antibody. Cell cycle inhibition by GSK-3beta is not mediated by the level of beta-catenin or by a direct effect on either the MAP kinase pathway or translation of mos and cyclin B1. These data indicate a novel role for GSK-3beta in Xenopus development: in addition to controlling specification of the dorsoventral axis in embryos, it mediates cell cycle arrest in oocytes.
Fisher
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DL
CNRS-CRBM, 34293 Montpellier Cedex 5, France. fisher@crbm.cnrs-mop.fr
Morin
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Dorée
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D000818:Animals; D016203:CDC2 Protein Kinase / Q000378:metabolism; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism / Q000502:physiology*; D002453:Cell Cycle / Q000502:physiology*; D019926:Cyclin B / Q000008:administration & dosage / Q000494:pharmacology; D003598:Cytoskeletal Proteins / Q000502:physiology*; D004789:Enzyme Activation; D005260:Female; D016195:G2 Phase; D038362:Glycogen Synthase Kinase 3; D038341:Glycogen Synthase Kinases; D006801:Humans; D008845:Microinjections; D009865:Oocytes / Q000166:cytology*; D015534:Trans-Activators; D029867:Xenopus Proteins; D014982:Xenopus laevis / Q000196:embryology*; D051176:beta Catenin
C495266:CTNNB1 protein, Xenopus; C495270:CTNNB1 protein, human; D019926:Cyclin B; D003598:Cytoskeletal Proteins; D015534:Trans-Activators; D029867:Xenopus Proteins; D051176:beta Catenin; D038341:Glycogen Synthase Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D016203:CDC2 Protein Kinase; D038362:Glycogen Synthase Kinase 3