Phosphorylation of the atypical kinesin Costal2 by the kinase Fused induces the partial disassembly of the Smoothened-Fused-Costal2-Cubitus interruptus complex in Hedgehog signalling.
The Hedgehog (Hh) family of secreted proteins is involved both in developmental and tumorigenic processes. Although many members of this important pathway are known, the mechanism of Hh signal transduction is still poorly understood. In this study, we analyse the regulation of the kinesin-like protein Costal2 (Cos2) by Hh. We show that a residue on Cos2, serine 572 (Ser572), is necessary for normal transduction of the Hh signal from the transmembrane protein Smoothened (Smo) to the transcriptional mediator Cubitus interruptus (Ci). This residue is located in the serine/threonine kinase Fused (Fu)-binding domain and is phosphorylated as a consequence of Fu activation. Although Ser572 does not overlap with known Smo- or Ci-binding domains, the expression of a Cos2 variant mimicking constitutive phosphorylation and the use of a specific antibody to phosphorylated Ser572 showed a reduction in the association of phosphorylated Cos2 with Smo and Ci, both in vitro and in vivo. Moreover, Cos2 proteins with an Ala or Asp substitution of Ser572 were impaired in their regulation of Ci activity. We propose that, after activation of Smo, the Fu kinase induces a conformational change in Cos2 that allows the disassembly of the Smo-Fu-Cos2-Ci complex and consequent activation of Hh target genes. This study provides new insight into the mechanistic regulation of the protein complex that mediates Hh signalling and a unique antibody tool for directly monitoring Hh receptor activity in all activated cells.
Ruel
Laurent
L
Institute of Signaling, Developmental Biology and Cancer Research, CNRS UMR 6543, Université de Nice-Sophia Antipolis, Parc Valrose, 06108 Nice Cedex 02, France.
Gallet
Armel
A
Raisin
Sophie
S
Truchi
Arnaud
A
Staccini-Lavenant
Laurence
L
Cervantes
Alexandra
A
Thérond
Pascal P
PP
D000818:Animals; D001665:Binding Sites; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000033:anatomy & histology / Q000196:embryology / Q000502:physiology; D004625:Embryo, Nonmammalian / Q000033:anatomy & histology / Q000378:metabolism; D053823:Hedgehog Proteins / Q000235:genetics / Q000378:metabolism*; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D016547:Kinesins / Q000235:genetics / Q000378:metabolism*; D046912:Multiprotein Complexes / Q000378:metabolism; D010641:Phenotype; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D034622:RNA Interference; D043562:Receptors, G-Protein-Coupled / Q000235:genetics / Q000378:metabolism*; D012694:Serine / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*; D000072086:Smoothened Receptor; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; C063459:En protein, Drosophila; D053823:Hedgehog Proteins; D018398:Homeodomain Proteins; D046912:Multiprotein Complexes; D043562:Receptors, G-Protein-Coupled; D000072086:Smoothened Receptor; D014157:Transcription Factors; C092937:ci protein, Drosophila; C107452:cos protein, Drosophila; C100664:smo protein, Drosophila; C077245:hh protein, Drosophila; D012694:Serine; C085770:fu protein, Drosophila; D017346:Protein Serine-Threonine Kinases; D016547:Kinesins