Skip to main content
. 2020 Aug 26;9(9):1973. doi: 10.3390/cells9091973

Figure 1.

Figure 1

Hedgehog (HH) signaling pathway. (A) In the absence of HH ligands (the OFF state), Patched (PTCH) inhibits Smoothened (SMO) from primary cilia, and Suppressor of Fused (SUFU) binds to glioma-associated oncogenes (GLIs) and inhibits their localization to primary cilia and nuclei. SUFU binding of GLI1 and GLI2 is degraded, leading to the GLI2 or GLI3 repressor forms, followed by N-terminus processing of GLI3 and a part of GLI2, suppressing GLI target gene expression. (B) In the presence of HH ligands (the ON state), one of the HH ligands binds to PTCH and prevents PTCH from inhibiting SMO. Next, SMO translocates to primary cilia to be fully activated. SMO then mainly activates GLI2, and the activated GLI2 induces GLI1 expression. GLI1 is also activated downstream of SMO. Activated GLI2 (GLI2A) and GLI1 further upregulate the expression of various GLI target genes. Only core components of the HH signaling pathway are shown in this figure, which is modified from our previous work [15].