title: Proteolysis of the Hedgehog signaling effector Cubitus interruptus requires phosphorylation by Glycogen Synthase Kinase 3 and Casein Kinase 1.
abstract: The secreted signaling molecule Hedgehog regulates gene expression in target cells in part by preventing proteolysis of the full-length Cubitus interruptus (Ci-155) transcriptional activator to the Ci-75 repressor form. Ci-155 proteolysis depends on phosphorylation at three sites by Protein Kinase A (PKA). We show that these phosphoserines prime further phosphorylation at adjacent Glycogen Synthase Kinase 3 (GSK3) and Casein Kinase I (CK1) sites. Alteration of the GSK3 or CK1 sites prevents Ci-155 proteolysis and activates Ci in the absence of Hedgehog. Ci-155 proteolysis is also inhibited if cells lack activity of the Drosophila GSK3, Shaggy, previously implicated in Wingless signaling. Conversely, Ci-155 levels are reduced in Hedgehog-responding cells by overexpression of PKA and the Drosophila CK1, Double-time, a regulator of circadian rhythms.
authors.affiliation: Department of Biological Sciences, Columbia University, New York, NY 10027, USA.
authors.forename: Mary Ann
authors.initials: MA
authors.lastname: Price
authors.forename: Daniel
authors.initials: D
authors.lastname: Kalderon
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000235:genetics / Q000378:metabolism*; D047388:Casein Kinases; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D004330:Drosophila; D029721:Drosophila Proteins / Q000378:metabolism*; D015971:Gene Expression Regulation, Enzymologic; D038362:Glycogen Synthase Kinase 3; D038341:Glycogen Synthase Kinases; D053823:Hedgehog Proteins; D066298:In Vitro Techniques; D008969:Molecular Sequence Data; D009154:Mutation; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D014157:Transcription Factors; D051153:Wnt Proteins; D029961:Zebrafish Proteins
chemical_list: D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D053823:Hedgehog Proteins; D011518:Proto-Oncogene Proteins; D014157:Transcription Factors; D051153:Wnt Proteins; D029961:Zebrafish Proteins; C092937:ci protein, Drosophila; C077245:hh protein, Drosophila; D011494:Protein Kinases; D038341:Glycogen Synthase Kinases; D047388:Casein Kinases; D017346:Protein Serine-Threonine Kinases; C080335:Sgg protein, Drosophila; D017868:Cyclic AMP-Dependent Protein Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D038362:Glycogen Synthase Kinase 3