Sonic hedgehog–Patched-1 protein interface (SHH–PTCH1 interface)

The Sonic hedgehog–Patched-1 (SHH–PTCH1) interface is the critical molecular junction that initiates the Hedgehog signaling pathway, essential for vertebrate organogenesis and stem cell homeostasis (UniProt P48747, Q13635). Under physiological conditions, the receptor PTCH1 acts as a tumor suppressor by repressing the activity of the transmembrane protein Smoothened (SMO). The binding of the SHH ligand to PTCH1 at this specific interface triggers the relief of this inhibition, allowing SMO to activate the GLI family of transcription factors (Qi et al., 2018, Nature). This interaction involves complex structural arrangements, including the coordination of zinc and calcium ions and the involvement of cholesterol moieties (Gong et al., 2018, Science). Dysregulation of the SHH–PTCH1 interface is strongly associated with developmental disorders like holoprosencephaly and various malignancies, most notably basal cell carcinoma and medulloblastoma (NCBI Gene ID: 6469). While clinical success has been achieved with SMO inhibitors like vismodegib, the SHH–PTCH1 interface is being actively investigated as a target for next-generation therapeutics. Molecules such as the small molecule robotnikinin and monoclonal antibodies like 5E1 are designed to block the pathway at its point of origin to circumvent SMO-based drug resistance (Stanton et al., 2009, Nature Chemical Biology).

Other names

SHH-PTCH1 complexSonic hedgehog-Patched-1 interaction siteHedgehog-Patched interfaceSHH-PTCH1 binding domain

Disruption of ligand-receptor binding to prevent the relief of Smoothened inhibition, thereby blocking downstream GLI-mediated transcription.