Skip to main content
. 2022 Apr 29;10:864035. doi: 10.3389/fcell.2022.864035

FIGURE 1.

FIGURE 1

Overview of canonical SHH signaling. (A) Representative signaling cascade when SHH signaling is shut off. In the absence of the SHH ligand, PTCH1 gets localized to the plasma membrane in the primary cilium and inhibits SMO. This causes the GLI family proteins to stay restrained by SUFU to facilitate their phosphorylation by PKA. Consequently, the GLI proteins undergo proteolysis to generate GLI-R that suppresses the transcription of target genes. (B) Representative signaling cascade when the SHH signaling is switched on. In the presence of the SHH ligand, PTCH1 gets inhibited by the SHH ligand-dependent interaction. This activates SMO, allowing its translocation to the cilia. Subsequently, GLI proteins dissociate from SUFU to enter the cell nucleus and activate the target genes. SHH, Sonic hedgehog; PTCH1, Patched1; SMO, Smoothened; GLI, Glioma-associated oncogene; SUFU, Suppressor of fused; PKA, Protein kinase A.