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. Author manuscript; available in PMC: 2013 Apr 22.
Published in final edited form as: Vitam Horm. 2012;88:115–140. doi: 10.1016/B978-0-12-394622-5.00006-7

Figure 6.2.

Figure 6.2

Regulation of GLI1 the isoforms by the canonical and noncanonical pathways. (A) Canonical activation of GLI1 is initiated by Shh, which binds and inhibits PTCH1 relieving PTCH1-mediated suppression of SMO. Derepressed SMO releases GLI1 from SUFU-mediated cytoplasmic sequestration. In turn, GLI1 translocalizes to the nucleus to induce transcription of target genes. Dyrk1 enhances GLI1 activity. Both GLI1ΔN and tGLI1 respond to Shh; however, it is unknown whether they are subjected to the regulation by other components of the Hedgehog pathway. (B) GLI1 can be affected by several noncanonical pathways. Activators of GLI1 include TGF-β, K-Ras, PKC-α, PDGF-A, PI3K-AKT, and estradiol. PKC-δ, PKA, and p53 suppress GLI1. The response of tGLI1 or GLI1ΔN to noncanonical pathway activation is currently unknown.