Expression array of stromal Mmp14-targeted mammary glands

Mammary gland branching morphogenesis is thought to depend on the mobilization of proteolytic machinery from the matrix metalloproteinase (MMP) family, namely MT1-MMP/MMP14, to drive coordinated epithelial cell invasion through the interstitial extracellular matrix, but the dominant effector has remained undefined. Unexpectedly, we find MMP14 controls postnatal mammary gland branching from the periductal stroma. Transcriptome profiling of stromal cell-targeted mammary glands was used to characterize the impact of stromal Mmp14-targeting on the growth factor and signaling cascades implicated in mammary gland morphogenesis. Transcriptome profiling of ductal networks and associated stroma was used to investigate the functional roles of MMP14 in the postnatal mammary gland stroma in an unbiased fashion. Intact mammary gland tissue was harvested from stromal cell-targeted conditional knockouts and wild-type littermates on a congenic C57BL/6J background at 4 weeks after birth for RNA extraction and hybridization on Affymetrix microarrays.