Smoothened (SMO) is a GPCR-
like receptor which, with Patched, mediates hedgehog signaling to regulate gene expression through the Gli transcription factors.
1 SANT 1 is a potent inhibitor of hedgehog signaling that acts by directly antagonizing SMO (IC
50 = 20 nM).
2 It counteracts SMO activation by the SMO agonist SAG but only partially competes with SAG binding to SMO.
2,3 SANT 1 targets inactive SMO while it is in the cytoplasm, before it relocates to the primary cilium and is activated.
4 Through antagonism of SMO, SANT 1 represses Gli-
mediated transcription in a variety of cell types.
4,5