Isolation of cell death-associated cDNAs from involuting mouse mammary epithelium

Although apoptosis is important in determining cell fate and maintaining tissue homeostasis, the initiation and control of apoptotic cell death in epithelium is not well understood. Post-lactationai involution of the mammary gland provides both an important developmental process and a normal physiological setting for studying apoptosis of epithelium. We used a differential screening strategy, based on previous studies correlating morphology with gene expression and nucleic acid integrity during mammary gland involution, to isolate genes involved in the regulation and execution of apoptotic cell death in regressing mammary epithelium. This screening strategy yielded a large number of genes the expression of which is significantly altered during mammary gland involution. These include genes associated with cell death processes, tissue remodelling and mesenchymal differentiation. In addition, a number of novel genes have been isolated. We have used Northern analysis and in situ hybridisation to study the expression of a selection of these putative death-associated genes during post-lactational mouse mammary gland involution.