Drosophila Smoothened phosphorylation sites essential for Hedgehog signal transduction.
The Hedgehog (Hh) signalling pathway is crucial for animal development and is aberrantly activated in several types of cancer. In Drosophila melanogaster, Hh signalling regulates target gene expression through the transcription factor Cubitus interruptus (Ci). Together, Protein Kinase A, Casein Kinase 1 and Glycogen Synthase Kinase 3 silence the pathway in the absence of ligand by phosphorylating Ci at a defined cluster of sites, thereby promoting its proteolytic conversion to a transcriptional repressor (Ci-75). In the presence of Hh, Ci-155 is no longer converted to Ci-75 and its ability to activate transcription is potentiated. All Hh responses require the seven transmembrane domain protein Smoothened, which itself becomes hyperphosphorylated during Hh signalling. Here we show that a cluster of protein kinase A and protein kinase A-primed casein kinase 1 phosphorylation sites in Smoothened, similarly distributed to those regulating Ci, are essential for Smoothened to transduce a Hh signal and for normal regulation of Smoothened protein levels.
Apionishev
Sergey
S
Department of Biological Sciences, Columbia University, 1212 Amsterdam Avenue, New York, NY 10027, USA.
Katanayeva
Natalya M
NM
Marks
Steven A
SA
Kalderon
Daniel
D
Tomlinson
Andrew
A
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites / Q000502:physiology; D019521:Body Patterning / Q000235:genetics; D047389:Casein Kinase I / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000196:embryology / Q000235:genetics / Q000502:physiology*; D004625:Embryo, Nonmammalian / Q000166:cytology / Q000196:embryology / Q000502:physiology; D018507:Gene Expression Regulation, Developmental / Q000235:genetics; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism; D053823:Hedgehog Proteins; D008969:Molecular Sequence Data; D010766:Phosphorylation; D043562:Receptors, G-Protein-Coupled / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*; D000072086:Smoothened Receptor; D014157:Transcription Factors; D019076:Transgenes / Q000235:genetics
D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D053823:Hedgehog Proteins; D043562:Receptors, G-Protein-Coupled; D000072086:Smoothened Receptor; D014157:Transcription Factors; C092937:ci protein, Drosophila; C100664:smo protein, Drosophila; C077245:hh protein, Drosophila; D047389:Casein Kinase I; D017868:Cyclic AMP-Dependent Protein Kinases; D038362:Glycogen Synthase Kinase 3