Ptch1 Knockout mouse models

Ptch1, the mouse ortholog of PTCH1, encodes a twelve-pass transmembrane receptor of the RND permease superfamily that, in the absence of ligand, catalytically restrains Smoothened by moving sterols away from the primary cilium, thereby suppressing GLI processing and pathway output. Sonic hedgehog binding, assisted by GAS1, CDON and BOC, triggers PTCH1 internalization and degradation, releasing SMO and converting GLI3 from repressor to activator. Loss of function underlies Gorlin syndrome, sporadic basal cell carcinoma and SHH-subgroup medulloblastoma, so heterozygous and conditional null alleles are the standard tumor initiation tools, while lacZ knockin reporters read pathway activity directly and remain widely used gradient readouts. Homozygous germline deletion is embryonic lethal with an open neural tube from constitutive pathway activation, mandating conditional strategies with lineage-appropriate Cre drivers. Ptch2 provides only partial repression, so compound loss sharpens tumor penetrance, particularly when modeling acquired vismodegib resistance.

Ptch1 null animals are straightforward to genotype and phenotype when survival is acceptable. They remain a standard background for pharmacology, biomarker, and rescue studies.