Project description:The mammary gland is a highly dynamic organ that mainly develops during puberty. Based on morphology and proliferation analysis, mammary stem cells (MaSCs) are thought to be close to or reside in the terminal end buds (TEBs) during pubertal development. However, exclusive stem cell markers are lacking, and therefore the true identity of MaSCs, including their location, multiplicity, dynamics and fate during branching morphogenesis, has yet to be defined. To gain more insights into the molecular identity and heterogeneity of the MaSC pool, we performed single cell transcriptome sequencing of mammary epithelial cells micro-dissected from ducts and TEBs during puberty. These data show that the behaviour of MaSCs cannot be directly linked to a single expression profile. Instead, morphogenesis of the mammary epithelium relies upon a heterogeneous population of MaSCs that functions long-term as a single equipotent pool of stem cells.
Project description:To investigate the impact of macrophages on cell population of mammary gland, we performed the single cell RNA sequencing of the macrophage-depleted mammary gland compared with control.
Project description:The mammary gland is a unique organ as it undergoes most of its development during puberty and adulthood. Characterising the hierarchy of the various mammary epithelial cells and how they are regulated in response to gestation, lactation and involution is important for understanding how breast cancer develops. Recent studies have used numerous markers to enrich, isolate and characterise the different epithelial cell compartments within the adult mammary gland. However, in all of these studies only a handful of markers were used to define and trace cell populations. Therefore, there is a need for an unbiased and comprehensive description of mammary epithelial cells within the gland at different developmental stages. To this end we used single cell RNA sequencing (scRNAseq) to determine the gene expression profile of individual mammary epithelial cells across four adult developmental stages; nulliparous, mid gestation, lactation and post weaning (full natural involution). Our data from 25,010 individual cells identifies 8 distinct mammary epithelial cell populations and allows their hierarchical structure across development to be charted. Interestingly, the effect of gestation and lactation appeared to be more pronounced for some cell types. For example, our analysis revealed a cluster of luminal progenitor cells in post involution glands, which is distinct from progenitors found in nulliparous glands. The data also showed that few clusters could be fully characterized by a single marker gene. We argue instead that the epithelial cells – especially in the luminal compartment – should rather be conceptualized as being part of a continuous spectrum of differentiation. This view highlights the plasticity of the tissue and might help to explain some of the conflicting results from lineage tracing studies.
Project description:The mammary gland epithelium is composed of basal cells (BC) and luminal cells (LC). Lineage tracing demonstrates that many glandular epithelia initially develop from multipotent basal stem cells (BaSCs) that are replaced in adult life by distinct pool of unipotent stem cells. However, adult unipotent BaSC can reactivate multipotency and give rise to LCs upon transplantation or oncogene expression, demonstrating the important plasticity of BaSCs in regenerative and pathological conditions, and suggesting that an active mechanism restricts multipotency in BaSCs during physiological conditions. Here, we assess whether basal and luminal cell-cell communication restricts multipotency in glandular epithelia.
Project description:Transcriptional profiling of mammary gland tumors from transgenic mice overexpressing the p110 or p75 isoform of CUX1. RNA was extracted from epithelial cells isolated using Laser-Capture Microdissection (LCM)
Project description:By transplanting mammary cells into the mammary fat pad in vitro to regenerate the whole mammary gland, we can study the interaction between mammary epithelial cells at single cell level
Project description:The mammary epithlium goes through the drastic reorganization during development, pregnancy, and menopause as well as by external hormones and its mimicry, which risks the gland for the specific type of breast cancer. Using a surgical menopausal (ovariectomized) mouse model, we assessed how mammary gland tissue was affected by 17β-estradiol (E2), progesterone (P4) and polybrominated diphenyl ethers (PBDEs). Then, we integrated the transcriptomes of 50K mouse and 24K human mammary epithelial cells from five different datasets and four individuals obtained by single-cell RNA sequencing (scRNAseq). The results indicated a putative trajectory originating from the embryonic mammary stem cells and differentiating into the three different epithelial lineage (Basal, Luminal alveolar, and Luminal hormone sensing) that were presumably sustained by unipotent progenitors in the postnatal glands. The identified lineage-specific gene sets inferred cells of origin of breast cancer using The Cancer Genome Atlas data and scRNAseq of human breast cancer. The comprehensive mammary cell atlas presented novel insights into the impact of the internal and external stimulati on the mammary epithelium in an unprecedented resolution.
Project description:Mammary gland branching morphogenesis is thought to relie on the mobilization of the membrane-anchored matrix metalloproteinase, Mmp14/MT1-MMP, to drive mammary epithelial invasion by remodeling the extracellular matrix and triggering associated signaling cascades. However, the roles that this proteinase plays during postnatal mammary gland development in vivo remain undefined. A mammary gland branching program that occurs during the first 4 weeks of postnatal mouse development, in tandem with recently developed Mmp14-floxed mice and MMTV-Cre transgenics that express Cre recombinase throughout the mammary epithelial cell compartment, were used to characterize the impact of deleting epithelial cell Mmp14 on mammary gland morphogenesis. Transcriptome profiling of mammary epithelial cells was used to investigate the functional roles of MT1-MMP in the postnatal mammary epithelial cell compartment in an unbiased fashion