Divergence of hedgehog signal transduction mechanism between Drosophila and mammals.
The Hedgehog (Hh) signaling pathway has conserved roles in development of species ranging from Drosophila to humans. Responses to Hh are mediated by the transcription factor Cubitus interruptus (Ci; GLIs 1-3 in mammals), and constitutive activation of Hh target gene expression has been linked to several types of human cancer. In Drosophila, the kinesin-like protein Costal2 (Cos2), which associates directly with the Hh receptor component Smoothened (Smo), is essential for suppression of the transcriptional activity of Ci in the absence of ligand. Another protein, Suppressor of Fused (Su(Fu)), exerts a weak negative influence on Ci activity. Based on analysis of functional and sequence conservation of Cos2 orthologs, Su(Fu), Smo, and Ci/GLI proteins, we find here that Drosophila and mammalian Hh signaling mechanisms have diverged, and that, in mouse cells, major Cos2-like activities are absent and the inhibition of the Hh pathway in the absence of ligand critically depends on Su(Fu).
Varjosalo
Markku
M
Molecular and Cancer Biology Program, Biomedicum, University of Helsinki and Department of Molecular Medicine, National Public Health Institute, P.O. Box 63, Helsinki FIN-00014, Finland.
Li
Song-Ping
SP
Taipale
Jussi
J
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002478:Cells, Cultured; D017124:Conserved Sequence; D004330:Drosophila / Q000235:genetics* / Q000378:metabolism*; D029721:Drosophila Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D019143:Evolution, Molecular; D053823:Hedgehog Proteins; D006801:Humans; D016547:Kinesins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D008322:Mammals; D051379:Mice; D008954:Models, Biological; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D017434:Protein Structure, Tertiary; D034622:RNA Interference; D012097:Repressor Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction / Q000235:genetics; D013045:Species Specificity; D015534:Trans-Activators / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*
D029721:Drosophila Proteins; D053823:Hedgehog Proteins; D012097:Repressor Proteins; C097059:Su(fu) protein, Drosophila; C490763:Sufu protein, mouse; D015534:Trans-Activators; C107452:cos protein, Drosophila; C077245:hh protein, Drosophila; D016547:Kinesins