Role of sonic hedgehog in maintaining a pool of proliferating stem cells in the human fetal epidermis

The mammalian epidermis is maintained by the ongoing proliferation of a subpopulation of keratinocytes known as epidermal stem cells. Sonic hedgehog (Shh) can regulate morphogenesis of hair follicles and several types of skin cancer, but the effect of Shh on proliferation of human putative epidermal stem cells (HPESCs) is poorly understood.We first found that Shh, its receptors Patched1 (Ptc1) as well as Smoothened (Smo) and its downstream...