Smoothened adopts multiple active and inactive conformations capable of trafficking to the primary cilium.
Activation of Hedgehog (Hh) signaling requires the transmembrane protein Smoothened (Smo), a member of the G-protein coupled receptor superfamily. In mammals, Smo translocates to the primary cilium upon binding of Hh ligands to their receptor, Patched (Ptch1), but it is unclear if ciliary trafficking of Smo is sufficient for pathway activation. Here, we demonstrate that cyclopamine and jervine, two structurally related inhibitors of Smo, force ciliary translocation of Smo. Treatment with SANT-1, an unrelated Smo antagonist, abrogates cyclopamine- and jervine-mediated Smo translocation. Further, activation of protein kinase A, either directly or through activation of Galphas, causes Smo to translocate to a proximal region of the primary cilium. We propose that Smo adopts multiple inactive and active conformations, which influence its localization and trafficking on the primary cilium.
Cardiovascular Research Institute, University of California San Francisco, San Francisco, California, United States of America.
Christopher W
CW
Wilson
Miao-Hsueh
MH
Chen
Pao-Tien
PT
Chuang
D000818:Animals; D002478:Cells, Cultured; D002923:Cilia / Q000378:metabolism* / Q000648:ultrastructure; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D004789:Enzyme Activation; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism; D019205:GTP-Binding Protein alpha Subunits, Gs / Q000378:metabolism; D053823:Hedgehog Proteins / Q000235:genetics / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D000072079:Patched Receptors; D000072081:Patched-1 Receptor; D010879:Piperazines / Q000378:metabolism; D011487:Protein Conformation; D021381:Protein Transport / Q000502:physiology; D011720:Pyrazoles / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism; D043562:Receptors, G-Protein-Coupled / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology; D000072086:Smoothened Receptor; D014704:Veratrum Alkaloids / Q000378:metabolism
D053823:Hedgehog Proteins; D000072079:Patched Receptors; D000072081:Patched-1 Receptor; D010879:Piperazines; C000606240:Ptch1 protein, mouse; D011720:Pyrazoles; D011956:Receptors, Cell Surface; D043562:Receptors, G-Protein-Coupled; C468919:SANT-1 compound; C491022:Smo protein, mouse; D000072086:Smoothened Receptor; D014704:Veratrum Alkaloids; C010206:jervine; D017868:Cyclic AMP-Dependent Protein Kinases; D019205:GTP-Binding Protein alpha Subunits, Gs; C000541:cyclopamine