Research Articles : New Evidence for the Involvement of the EGF Receptor Pathway in Hair Follicle Morphogenesis in uncv Mice

The document discussed the development of basal cell carcinoma (BCC) through the study of hair follicles, focusing on the role of Sonic hedgehog (Shh) signaling and its interaction with the insulin-like growth factor (IGF) axis. It highlighted the overexpression of IGF binding protein-2 (IGFBP-2) in hair follicle cells of mice with activated Shh signaling, which led to an expansion of the stem cell niche and inhibition of cell differentiation. This transformation was linked to the development of BCC, with evidence showing IGFBP-2 expression in human BCC as well.

The study demonstrated that activation of β-catenin signaling in adult mouse skin led to the formation of ectopic hair follicles, indicating that β-catenin plays a crucial role in hair follicle development. By inducing a stabilizing β-catenin mutation, researchers observed increased hair growth and the formation of new hair follicles in mutant mice compared to controls. The study used a genetic model involving Krt5-rtTA tetO-Cre Ctnnb1(Ex3)fl/+ mice treated with doxycycline, which resulted in densely packed, irregularly spaced hair follicles in an abnormal growth phase. The findings suggested that β-catenin signaling could reprogram epidermal cells to adopt a hair follicle fate, even in typically hairless regions like footpad skin.