Targeted Expression of Activated ErbB-2 to the Epidermis of Transgenic Mice Elicits Striking Developmental Abnormalities in the Epidermis and Hair Follicles

The study investigated the role of the erbB-2 proto-oncogene in skin development by creating transgenic mice with an activated erbB-2 oncogene under the control of the human keratin 14 promoter. This targeted expression led to significant developmental abnormalities in the epidermis and hair follicles. All transgenic mice exhibited severe skin phenotypes, including epidermal hyperplasia, preneoplasia, papilloma, hyperkeratosis, and dyskeratosis. Most hair follicles were replaced by abnormal hyperproliferative squamous invaginations, and the remaining follicles showed severe hyperplasia and disorganization. All but one of the transgenic mice died before or shortly after birth due to skin and esophagus defects. These findings suggested that erbB-2 signaling played a crucial role in epidermal growth, differentiation, and hair follicle morphogenesis.