Expression array of early postnatal Mt1-mmp-targeted mammary glands

Mammary gland branching morphogenesis is thought to depend on the mobilization of the membrane-anchored matrix metalloproteinases, MT1-MMP and MT2-MMP, that drive epithelial cell invasion by remodeling the extracellular matrix and triggering associated signaling cascades. However, the roles that these proteinases play during mammary gland development in vivo remains undefined. A mammary gland branching program that occurs during the first 10 days of early postnatal development was used to characterize the impact of global Mt1-mmp or Mt2-mmp targeting on mammary gland morphogenesis. Transcriptome profiling of ductal networks and associated stroma was used to investigate the functional roles of MT1-MMP in the early postnatal mammary gland in an unbiased fashion. Intact mammary gland tissue was harvested from global knockout [Mt1-mmp(-/-)] mice and wild-type [Mt1-mmp(+/+)] littermates on an outbred Swiss Black background at postnatal day 10 for RNA extraction and hybridization on Affymetrix microarrays.