Project description: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.
Project description:In this study, we conducted single-cell RNA sequencing (scRNA-seq) studies to investigate the impact of high-fat diet (HFD)-induced obesity on transcriptomic landscapes of stromal and immune cells in mammary glands of Brca1-/-;p53+/- mice, an animal breast cancer model. The scRNA-seq profiling data showed that five different subtypes of stromal fibroblasts existed in mouse mammary glands. HFD-induced obesity led to upregulated expression of extracellular matrix (ECM) genes (Col3a1, Col6a3, Eln, and Sparc) and downregulated expression of immunoregulatory genes (Iigp1, Ccl2, and Cxcl10) in these stromal subtype cells. These findings, taken together, suggest that obesity alters the ECM composition and immune ecosystem through modulating the functionality of mammary stromal cells. Moreover, scRNA-seq analysis of mammary immune cells indicated that HFD-induced obesity promoted the generation and/or recruiting of pro-tumorigenic M2 macrophages in mammary glands.
