Regulation of genes encoding proteolytic enzymes during mammary gland development

摘要

The expression of proteolytic enzymes is essential for the tissue remodelling processes that take place during mammary gland development. The available micro-array data suggest that a number of MMP genes (but not all) are activated co-ordinately. Similarly, not all aminopeptidase and carboxypetidase genes are differentially regulated during mammary development. Comparison of data obtained by micro-array and quantitative PCR shows that the two experimental approaches are in agreement for highly expressed genes. Genes that are expressed at a low level (e.g., MMP7), however, may escape detection as differentially regulated by the micro-array approach. The available micro-array data (e.g., in the case of EGF) suggest that different molecules are involved in the induction of genes encoding proteolytic enzymes during pregnancy and involution. This is in accordance with the underlying biology. During pregnancy the epithelium requires tissue-remodelling enzymes in order to migrate, proliferate and differentiate in the mammary fat pad, whereas during involution proteolytic activity is required to remove a regressing epithelium and support the differentiation of adipocytes.