Expression of a Dominant Negative Mutant of Epidermal Growth Factor Receptor in the Epidermis of Transgenic Mice Elicits Striking Alterations in Hair Follicle Development and Skin Structure.

The study investigated the role of the epidermal growth factor receptor (EGFR) in skin by creating transgenic mice with a dominant negative mutant of EGFR in the epidermis and hair follicles. These mice exhibited short, waved hair and curly whiskers initially, but over time, their hair became sparse and atrophic, leading to severe alopecia. Histological analysis revealed significant disruptions in hair follicle development, with follicles failing to enter the catagen stage, resulting in necrosis and disappearance, along with skin inflammation. The interfollicular epidermis showed hyperplasia and increased markers of hyperproliferation. EGFR function was inhibited, as evidenced by reduced autophosphorylation upon EGF stimulation. The findings suggested that EGFR played a crucial role in hair cycle progression and epidermal growth and differentiation.