title: The novel tyrosine kinase ZAK1 activates GSK3 to direct cell fate specification.
abstract: Inhibition of GSK3 by 7-TM Wnt/wg receptor signaling is critical for specifying embryonic cell fate patterns. In Dictyostelium, the 7-TM cAMP receptors regulate GSK3 by parallel, antagonistic pathways to establish a developmental body plan. We describe here a novel tyrosine kinase, ZAK1, downstream of 7-TM cAMP receptor signaling that is required for GSK3 activation during development. zak1-nulls have reduced GSK3 activity and are defective in GSK3-regulated developmental pathways. Moreover, recombinant ZAK1 phosphorylates and activates GSK3 in vitro. We propose that ZAK1 is a positive regulator of GSK3 activity required for cell pattern formation in Dictyostelium and speculate that similar mechanisms exist to antagonize Wnt/wg signaling for metazoan cell fate specification.
authors.affiliation: Laboratory of Cellular and Developmental Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA.
authors.forename: L
authors.initials: L
authors.lastname: Kim
authors.forename: J
authors.initials: J
authors.lastname: Liu
authors.forename: A R
authors.initials: AR
authors.lastname: Kimmel
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000235:genetics / Q000378:metabolism*; D003001:Cloning, Molecular; D000242:Cyclic AMP / Q000378:metabolism; D018076:DNA, Complementary; D004023:Dictyostelium / Q000201:enzymology* / Q000254:growth & development; D004789:Enzyme Activation; D038362:Glycogen Synthase Kinase 3; D008969:Molecular Sequence Data; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D011817:Rabbits; D011953:Receptors, Cyclic AMP / Q000378:metabolism
chemical_list: C079747:CAR3 protein, Dictyostelium discoideum; D018076:DNA, Complementary; D011953:Receptors, Cyclic AMP; D000242:Cyclic AMP; D011505:Protein-Tyrosine Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D038362:Glycogen Synthase Kinase 3