Indian hedgehog protein (IHH)

Indian hedgehog protein (IHH) is a key mammalian signaling molecule of the **hedgehog family**, encoded by the *IHH* gene. It plays an essential role in **regulating the growth, differentiation, and maturation of chondrocytes** during endochondral ossification, which is critical for bone and cartilage development. IHH is secreted primarily by prehypertrophic chondrocytes and acts by creating a feedback loop with parathyroid hormone-related peptide (PTHrP), thereby controlling the pace and position of chondrocyte maturation and osteoblast differentiation in developing long bones. Mutations in IHH are responsible for human genetic disorders such as brachydactyly type A1, and dysregulation of hedgehog signaling is implicated in several pathologies, including bone diseases and cancer. While there are currently no direct IHH-targeting drugs approved, inhibitors of the hedgehog pathway are used in cancer therapy, targeting pathway activation downstream of all hedgehog ligands, including IHH[1][3][6].

Other names

IHHIndian hedgehog signaling moleculeHedgehog protein IHHIndian hedgehog homolog (Drosophila)

Hedgehog pathway inhibitors block Smoothened (Smo) activation, thereby preventing signal transduction downstream of IHH