Small Molecule Modulation of Smoothened Activity

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 99; no. 22; pp. 14071 - 14076
• Main Authors: Chen, James K., Taipale, Jussi, Young, Keith E., Maiti, Tapan, Beachy, Philip A.
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 29.10.2002; National Acad Sciences
• Subjects: 3T3 Cells; Agonists; Animals; Benzamides - chemistry; Benzamides - pharmacology; Benzimidazoles - chemistry; Benzimidazoles - pharmacology; Binding Sites; Biochemistry; Biological Sciences; Cell Line; Cell lines; Cinnamates - chemistry; Cinnamates - pharmacology; COS cells; Cyclohexylamines - chemical synthesis; Cyclohexylamines - pharmacology; Embryos; GTP-Binding Proteins; Hedgehog Proteins; HEK293 cells; Humans; Inhibitory concentration 50; Mice; Molecules; NIH 3T3 cells; Piperazines - chemistry; Piperazines - pharmacology; Piperidines - chemistry; Piperidines - pharmacology; Proteins; Pyrazoles - chemistry; Pyrazoles - pharmacology; Pyridines - chemistry; Pyridines - pharmacology; Receptors, Cell Surface - antagonists & inhibitors; Receptors, G-Protein-Coupled; Smoothened Receptor; Sulfides - chemistry; Sulfides - pharmacology; Thiophenes - chemical synthesis; Thiophenes - pharmacology; Trans-Activators - agonists; Tumors; Ungulates
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.182542899

Smoothened (Smo), a distant relative of G protein-coupled receptors, mediates Hedgehog (Hh) signaling during embryonic development and can initiate or transmit ligand-independent pathway activation in tumorigenesis. Although the cellular mechanisms that regulate Smo function remain unclear, the direct inhibition of Smo by cyclopamine, a plant-derived steroidal alkaloid, suggests that endogenous small molecules may be involved. Here we demonstrate that SAG, a chlorobenzothiophene-containing Hh pathway agonist, binds to the Smo heptahelical bundle in a manner that antagonizes cyclopamine action. In addition, we have identified four small molecules that directly inhibit Smo activity but are structurally distinct from cyclopamine. Functional and biochemical studies of these compounds provide evidence for the small molecule modulation of Smo through multiple mechanisms and yield insights into the physiological regulation of Smo activity. The mechanistic differences between the Smo antagonists may be useful in the therapeutic manipulation of Hh signaling.