Dhh Conditional Knockout mouse models

Dhh, mouse ortholog of human DHH, encodes Desert hedgehog, an autoprocessing morphogen that undergoes intramolecular cleavage with cholesterol modification and palmitoylation before binding PTCH1 to relieve inhibition of SMO, stabilizing GLI2 and GLI3 for target transcription. Unlike the broadly expressed SHH, its expression is restricted chiefly to Sertoli cells, where it acts on peritubular and Leydig progenitors to drive steroidogenic differentiation, and to Schwann cells, where it builds the perineurium and nerve-blood barrier. Human biallelic mutations cause 46,XY gonadal dysgenesis with or without minifascicular polyneuropathy, a phenotype well matched by patient-derived missense knockins that impair processing or receptor binding. Mouse nulls are viable but males show Leydig hypoplasia, infertility, and abnormal nerve sheaths, so constitutive deletion is workable while conditional floxed alleles with Amh-Cre or Dhh-Cre separate testicular from peripheral nerve requirements. Because Shh and Ihh signal through the same PTCH1 and SMO machinery, interpret pathway-level readouts with paralog expression documented for the tissue scored.

Dhh conditional knockout mice carry a floxed allele so you delete function only where Cre is active. The germline allele stays intact until you cross to a tissue specific Cre. Labs reach for this design when a global knockout is lethal, when they need adult onset loss, or when regional redundancy hides a whole body phenotype.