patched

Hedgehog (Hh) proteins, important regulators of development, bind the cell-surface protein Patched, allowing activation of Smoothened. In vertebrates, this ultimately leads to the activation of the zinc-finger transcription factors of the Gli family. Overactivation of this pathway contributes to certain cancers, including glioblastoma, for which the Gli proteins are named. Hh antagonist VIII is a cell-permeable quinazolinyl-urea compound that has been shown to inhibit Gli transcription activity with an IC50 value of 70 nM.

Smoothened (SMO) is a GPCR-like receptor which, with Patched, mediates hedgehog signaling to regulate gene expression through the Gli transcription factors. 20(S)-hydroxy Cholesterol (20(S)-OHC) is an oxysterol which binds SMO and activates hedgehog signaling (EC50 = 3 μM), and this activation is selective for the nat-20(S)-OHC enantiomer. Nat-20(S)-OHC synergizes with the SMO agonist SAG, suggesting an allosteric effect. Nat-20(S)-yne is a form of nat-20(S)-OHC with a terminal alkyne group, which can be used in linking reactions known as click chemistry. Click chemistry involves highly dependable and specific azide-alkyne bioconjugation reactions and can be used to capture or immobilize bioactive molecules. Thus, nat-20(S)-yne has been conjugated with magnetic beads to demonstrate that nat-20(S)-OHC directly binds SMO.

Patidegip, laos known as Saridegib and IPI-926, is an orally bioavailable, cyclopamine-derived (for structure comparison see Fig 1) inhibitor of the Hedgehog (Hh) pathway with potential antineoplastic activity. Specifically, Hedgehog pathway inhibitor IPI-926 binds to and inhibits the cell membrane-spanning G-protein coupled receptor SMO, which may result in the suppression of Hh pathway signaling and a decrease in tumor cell proliferation and survival. SMO is activated upon binding of Hh ligand to the cell surface receptor Patched (PTCH); inappropriate activation of Hh signaling and uncontrolled cellular proliferation may be associated with SMO mutations.

HL2-m5 是 sonic hedgehog patched (Shh PTCH1) 相互作用的抑制剂，其对 Shh 的 Kd 为 170 nM。HL2-m5 能有效抑制 Hedgehog 信号通路的激活和 Gli 控制基因的转录，IC50 为 230 nM。