Project description:The mammary gland develops mainly postnatally, when during pregnancy the epithelium grows out into the mammary fat pad and forms a network of epithelial ducts. During pregnancy, these ducts branch and bud to form alveoli. These alveoli produce the milk during lactation. After 7 days of lactation, involution was induced by force weaning the pups. The newly formed epithelium undergoes apoptosis and is removed from the tissue by neighbouring epithelial cells. Tissue remodelling leads to a morphology resembling a gland of a pre-pregnant mouse. Microarray analysis was used to measure mRNA expression of genes during puberty, pregnancy, lactation and involution in a Balb/c mouse strain. Keywords: developmental time course
Project description:Mammary gland is a dynamic organ which undergoes most of its structural development after birth under cyclic control of ovarian hormones such as estrogen and progesterone. Using 4-vinylcyclohexene diepoxide (VCD) menopause model, we investigated the effect of ovarian hormones on mouse mammary glands. In particular, we focused on mouse mammary gland fibroblasts because they are one of the known crucial players but yet to be characterized well. With integrated analysis including six other publicly available datasets as well as mammary epithelium atlas data, we comprehensively described the characters of mouse mammary gland (e.g. potential commitment to mammary gland development, response to estrogens, developmental relationship, and crosstalk with mammary epithelium) in a population specific manner. Furthermore, we investigated the effect of endocrine disrupting chemical named polybrominated diphenyl ethers (PBDEs) in either of absence or presence of ovarian hormones on whole cellular components of mouse mammary gland including epithelial cells, fibroblasts, and immune cells at a single cell level.
Project description:The mammary gland develops mainly postnatally, when during pregnancy the epithelium grows out into the mammary fat pad and forms a network of epithelial ducts. During pregnancy, these ducts branch and bud to form alveoli. These alveoli produce the milk during lactation. After 7 days of lactation, involution was induced by force weaning the pups. The newly formed epithelium undergoes apoptosis and is removed from the tissue by neighbouring epithelial cells. Tissue remodelling leads to a morphology resembling a gland of a pre-pregnant mouse. Microarray analysis was used to measure mRNA expression of genes during puberty, pregnancy, lactation and involution in a Balb/c mouse strain. Experiment Overall Design: Total RNA was extracted from the 4th (inguinal) gland after removal of the lymph node. Individual samples represent RNA from one gland of one mouse. Samples were taken in triplicate (i.e. three mice per triplicate) for 18 time points of development.
Project description:The identification of genes driving organ development is central to understanding which signaling pathways drive the pathogenesis of various diseases including cancer. This dataset depicts the proteomic changes observed in C57BL/6J mice expressing wild-type or 3SA-phospho mutant versions of the Bcl-2-associated death promoter, BAD. This data shows that BAD regulates postnatal mammary gland morphogenesis in puberty. Three conserved serine residues on BAD are co-ordinately phosphorylated to regulate its activity. Non-phosphorylated BAD mutant delayed pubertal ductal elongation. This defect was specific to the epithelial compartment as transplant and ex vivo organoid assays of mutant epithelium recapitulated decreased tubule migration. Proteomic signature between BAD+/+ and phosphomutant BAD-3SA mammary glands identified differences in actin-binding and focal adhesion components. Mechanistically, non-phosphorylated BAD impedes protein translation, specifically in protrusions, through aberrant hypophosphorylated 4E-BP1. These findings reveal a critical enhancement of localized translation for efficient pubertal-mammary-gland morphogenesis and identifies BAD as a novel regulator of this process.
Project description:Pregnancy is the major modulator of mammary gland activity. It induces a tremendous expansion of the mammary epithelium and the generation of alveolar structures for milk production. Anecdotal evidence from multiparous humans indicates that the mammary gland may react less strongly to the first pregnancy than it does to subsequent pregnancies. Here we verify that the mouse mammary gland responds more robustly to a second pregnancy, indicating that the gland retains a long-term memory of pregnancy. A comparison of genome-wide profiles of DNA methylation in isolated mammary cell types revealed substantial and long lasting alterations. The majority of these alterations affect sites occupied by the Stat5a transcription factor and mark specific genes that are upregulated during pregnancy. We postulate that the epigenetic memory of a first pregnancy primes the activation of gene expression networks that promote mammary gland function in subsequent reproductive cycles. More broadly, our data indicate that physiological experience can broadly alter epigenetic states, functionally modifying the capacity of the affected cells to respond to later stimulatory events.
Project description:Background: The differential expression pattern of microRNAs (miRNAs) during mammary gland development might provide insights into their role in regulating the homeostasis of the breast epithelium. Our aim was to analyse these regulatory functions by deriving a comprehensive tissue-specific combined miRNA and mRNA expression profile of post-natal mouse mammary gland development. We measured the expression of 318 individual murine miRNAs by bead-based flow-cytometric profiling of whole mouse mammary glands throughout a 16-point developmental time course, including juvenile, puberty, mature virgin, gestation, lactation, and involution stages. In parallel whole-genome mRNA expression data were obtained. Results: One third (n = 102) of all murine miRNAs analysed were present during mammary gland development. MicroRNAs were represented in seven temporally co-expressed clusters, which were enriched for both miRNAs belonging to the same family and breast cancer-associated miRNAs. Global miRNA and mRNA expression was significantly reduced during lactation and the early stages of involution after weaning. For most detected miRNA families we did not observe systematic changes in the expression of predicted targets. For miRNA families whose targets did show significant changes, we observed inverse patterns of miRNA and target expression. The datasets are made publicly available and the combined expression profiles represent an important community resource for mammary gland biology research. Conclusions: MicroRNAs were expressed in co-regulated clusters during mammary gland development. Breast cancer-associated miRNAs were significantly enriched in these clusters. The mechanism and functional consequences of this miRNA co-regulation and its correlation with mRNA expression provide new avenues for research into mammary gland biology and generates candidates for functional validation. This SuperSeries is composed of the following subset Series: GSE15054: Characterisation of microRNA expression in post-natal mouse mammary gland development [gene] GSE15055: Characterisation of microRNA expression in post-natal mouse mammary gland development [miRNA] Refer to individual Series
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:Identify gene expression changes in the absence of Plk2 Disruptions in polarity and mitotic spindle orientation contribute to the progression and evolution of tumorigenesis. However, little is known about the molecular mechanisms regulating these processes in vivo. Here we demonstrate that Polo-like kinase 2 (Plk2) regulates mitotic spindle orientation in the mammary gland and is a putative tumor suppressor. Plk2 is highly expressed in the mammary gland and is required for proper mammary gland development. Loss of Plk2 leads to increased mammary epithelial cell proliferation and ductal hyperbranching. Additionally a novel role for Plk2 in regulating the orientation of the mitotic spindle and maintaining proper cell polarity in the ductal epithelium was discovered. In support of a tumor suppressor function for Plk2, loss of Plk2 increased the formation of lesions in multiparous glands. Collectively, these results demonstrate a novel role for Plk2 in regulating mammary gland development and as a tumor suppressor in mammary tumorigenesis. Disruptions in polarity and mitotic spindle orientation contribute to the progression and evolution of tumorigenesis. However, little is known about the molecular mechanisms regulating these processes in vivo. Here we demonstrate that Polo-like kinase 2 (Plk2) regulates mitotic spindle orientation in the mammary gland and is a putative tumor suppressor. Plk2 is highly expressed in the mammary gland and is required for proper mammary gland development. Loss of Plk2 leads to increased mammary epithelial cell proliferation and ductal hyperbranching. Additionally a novel role for Plk2 in regulating the orientation of the mitotic spindle and maintaining proper cell polarity in the ductal epithelium was discovered. In support of a tumor suppressor function for Plk2, loss of Plk2 increased the formation of lesions in multiparous glands. Collectively, these results demonstrate a novel role for Plk2 in regulating mammary gland development and as a tumor suppressor in mammary tumorigenesis. Comparison between Plk2 +/+ (n=3) and Plk2 -/- (n=3) mouse mammary epithelial cells
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:RNA from MMTV-Cre;Sox9flox/flox mouse mammary glands were compared to RNA from MMTV-Cre;Sox9+/flox glands. Results indicate that Sox9 regulates several genes that impact ductal morphogenesis in the mammary gland. The portion of the fourth mammary gland that is proximal to the intra-mammary gland lymph nodes was dissected from four 5-week-old MMTV-Cre;Sox9flox/flox females and four MMTV-Cre;Sox9+/flox females of the same age. Total RNA from each gland was extracted and hybridized to separate Affymetrix Gene 1.0 ST chips.