Biogenesis and function of mouse mammary epithelium depends on the presence of functional alpha-catenin

Alpha-catenin is a structural molecule and essential to the function of epithelial adherents junctions. Its role in the morphogenesis of mammary epithelium was explored using experimental mouse genetics. Since loss of alpha-catenin in mice leads to embryonic lethality, the a.-catenin gene was flanked by loxP sites and inactivated in mammary epithelium using the WAP-Cre and MMTV-Cre transgenes. Loss of a-catenin arrested alveolar epithelial expansion. These cells lacked proper polarity and markers of functional differentiation, which resulted in impaired milk protein gene expression. Without alpha-catenin, increased epithelial cell death was observed at parturition and the tissue resembled an involuted gland that is normally observed after weaning. Lastly, no tumors were detected in mammary tissue lacking a-catenin. (C) 2003 Elsevier Ireland Ltd. All rights reserved.