Gene transcript alterations exhibited in luminal and basal epithelial compartments with impaired Ror2 signaling
ABSTRACT: Microarray analyses revealed distinct gene expression alterations in the luminal and basal epithelial compartments in the absence of Ror2 with marked alterations observed in genes associated with actin filament-based processes and the actin cytoskeletal network. Given that Ror2 expression resides in both basal and luminal epithelial cells, we wanted to identify compartment-specific functions for Ror2 in coordinating development. Accordingly, luminal and basal epithelial cell populations from shLUC and shRor2 outgrowths were isolated by FACS separation on the basis of CD24 and CD29 surface marker expression and gene expression analysis was subsequently performed using Agilent microarrays.
Project description:The goal of the experiment was to carry out a transcriptome analysis of the three main epithelial cell populations of the mouse mammary gland, the basal/myoepithelial, luminal estrogen receptor negative (ER-) and luminal estrogen receptor positive (ER+) cells, to identify cell-type specific differences in gene expression. Three replicates arrays were carried out for each of the three populations (a total of nine arrays). Each replicate was a genuine biological replicate from RNA harvested from completely independent cell preparations. Each sample was isolated from preparations of mammary epithelium derived fourth mammary fat pads of 8 * 10 week old virgin female FVB mice. Each preparation was from a pool of 10 * 20 animals (20 * 40 fat pads).
Project description:We present an organoid regeneration assay in which freshly dissociated human mammary epithelial cells from healthy donors are grown in adherent/rigid or floating/compliant collagen I gels. In both conditions, luminal progenitors (CD49f+EpCAM+) form spheres, whereas basal cells (CD49fhiEpCAM-) generate branched ductal structures. However, in compliant but not rigid collagen gels, branching ducts form alveoli at their tips, express basal and luminal markers at correct positions and display contractility, which is required for alveologenesis. Thereby, branched structures generated in compliant collagen gels resemble terminal ductal-lobular units (TDLUs), the functional units of the mammary gland. Moreover, the membrane metallo-endopeptidase CD10 as an additional surface marker enriches for TDLU-formation and reveals the presence of stromal cells within the CD49fhiEpCAM- population. In summary, we describe a defined in vitro assay system to quantify cells with regenerative potential and systematically investigate their interaction with the physical environment at distinct steps of morphogenesis. Comparison of three cell populations derived from FACS-sorted primary human mammary epithelial cells: luminal progenitors, CD10+ basal cells and CD10- basal cells.
Project description:Mammary gland development and luminal differentiation occur largely postnatally during puberty and pregnancy. To explore the role of DNA methylation in luminal cell differentiation and pregnancy-induced changes, we determined the genome-wide DNA methylation and gene expression profiles of mammary epithelial stem, luminal progenitor, and mature luminal cells at different reproductive stages. We found that pregnancy had the most significant effects on stem cells, inducing a distinct epigenetic state that remained stable through life. Integrated analysis of gene expression, DNA methylation, and histone modification profiles revealed cell type and reproductive stage-specific changes in molecular signatures. We also identified p27 and TGFβ signaling as key regulators of luminal progenitor cell proliferation based on their expression patterns and by the use of explant cultures. Our results suggest relatively minor changes in DNA methylation during luminal cell differentiation as compared to the significant effects of pregnancy on mammary epithelial stem cells. Mammary glands were collected from mice treated with DNA methylation inhibitor 5-azacytidine (AzaC) and histone deacetylase inhibitor valproic acid (VPA) at non-pregnant and pregnant stages for RNA extraction and hybridization on Affymetrix microarrays.
Project description:Regulation of cell-cell junction formation and regulation of cell migration were enriched among EMT (Epithelial-Mesenchymal Transition)-associated alternatively splicing events. Our analysis suggested that most EMT-associated alternative splicing events are regulated by one or more members of the RBFOX, MBNL, CELF, hnRNP or ESRP classes of splicing factors. The EMT alternative splicing signature was confirmed in human breast cancer cell lines, which could be classified into basal and luminal subtypes based exclusively on their EMTassociated splicing pattern. Expression of EMT-associated alternative mRNA transcripts was also observed in primary breast cancer samples, indicating that EMT-dependent splicing changes occur commonly in human tumors. The functional significance of EMT-associated alternative splicing was tested by expression of the epithelial-specific splicing factor ESRP1 or depletion of RBFOX2 in mesenchymal cells, both of which elicited significant changes in cell morphology and motility towards an epithelial phenotype, suggesting that splicing regulation alone can drive critical aspects of EMT-associated phenotypic changes. The molecular description obtained here may aid in the development of new diagnostic and prognostic markers for analysis of breast cancer progression. Examination of transcriptomes of HMLE/Twist-ER before and after induction of EMT by tamoxifen
Project description:RUNX1 encodes a RUNX family transcription factor (TF) and was recently identified as a novel mutated gene in human luminal breast cancers. We found that Runx1 is expressed in all subpopulations of murine mammary epithelial cells (MECs) except the secretory alveolar luminal cells. Conditional knockout of Runx1 in MECs by MMTV-Cre led to a decrease in luminal MECs, largely due to a profound reduction in the estrogen receptor (ER)-positive mature luminal subpopulation, a phenotype that could be rescued by loss of either Trp53 or Rb1. Mechanistically RUNX1 represses Elf5, a master regulatory TF gene for alveolar cells, and activates Foxa1, a key mature luminal TF gene involved in the ER program. Collectively, our data identified a key regulator of the ER+ luminal lineage whose disruption may contribute to development of ER+ luminal breast cancer when under the background of either TP53 or RB1 loss. Thoracic and inguinal mammary glands from 3 MMTV-Cre;Runx1L/L;R26Y and 3 MMTV-Cre;Runx1+/+;R26Y adult virgin females were dissected out, minced and digested to single cell suspension. Runx1L is the floxed conditional knockout allele of Runx1. R26Y is a conditional YFP reporter that would be turned on upon Cre-mediated recombination. FACSaria machine was used to sort out the YFP-marked luminal epithelial cell population of each of these 6 mice. Total RNA was isolated with Qiagen RNeasy kit and subsequently amplified by Nugen V2 and applied to Affymetrix mouse genome 430 2.0 arrays.
Project description:Transcriptional profiling of different mouse mammary cellular compartments (basal, luminal and stromal) under define hormone treatments: estrogen, progesterone, estrogen plus progesterone and the vehicle control. Goal was to determine the effect of ovarian hormones on mammary cellular compartment gene expression. Four-condition experiment within each cellular compartment. vehicle vs. estrogen, progesterone and estrogen plus progesterone. Biological replicates: 3 vehicle control, 4 estrogen treatment, 3 progesterone treatment, 4 estrogen plus progesterone treatment in each epithelial compartment (luminal, basal). 3 vehicle control, 3 estrogen, 3 progesterone, 3 estrogen plus progesterone in the stromal compartment.
Project description:The organisation of the mammary epithelial cell hierarchy and how these cells relate to the presentation of human breast tumours is poorly understood. Our results demonstrate that the luminal cell compartment of the mouse mammary gland can be resolved into terminally differentiated oestrogen receptor (ER)+ luminal cells, ER+ luminal progenitors and ER- luminal progenitors. The ER+ luminal progenitors are unique in regards to cell survival, as they are relatively insensitive to loss of oestrogen and progesterone when compared to the other types of mammary epithelial cells. Analysis of normal human breast tissue reveals a similar hierarchical organisation that is composed of terminally differentiated luminal cells and relatively differentiated (EpCAM+CD49f+ALDH-) and undifferentiated (EpCAM+CD49f+ALDH+) luminal progenitors. In addition, approximately one third of human breast samples examined contained an additional population that had a luminal progenitor phenotype, but is characterised by low expression of ERBB3 and low proliferative potential. Parent-progeny relationship experiments demonstrated that all luminal progenitor populations in both species are highly plastic and, at low frequencies, can generate progeny representing all mammary cell types. Gene expression profiling demonstrates that the ER- luminal progenitors in the mouse and the undifferentiated ALDH+ luminal progenitors in the human have gene signatures that resemble those obtained from basal-like breast tumours. Overall, our work reveals a more defined mammary cell hierarchy, which may in turn provide greater insight into the aetiology of breast cancer. Normal human breast tissues from reduction mammoplasties were dissociated into single cells and the epithelial cell populations were flow sorted. Total RNA was extracted for each group in 11 independent patient samples.
Project description:Skin-mammary specific knockout (SSKO) of Pygo2 (K14-cre; Pygo2 flox/-) , a WNT signaling co-activator, results in defective mouse mammary gland development. The FACS sorted mammary stem cell (MaSC)/basal population from Pygo2 SSKO mammary gland displays biased differentiation towards luminal/alveolar lineage in vitro, and reduced regeneration rate of new mammary gland in vivo To gain the insight into gene expression profiles in control and Pygo2 SSKO mammary epithelial cells (MECs), we sorted the freshly isolated mouse MECs into MaSC/basal (Lin-CD29hiCD24+) and mature luminal population (Lin-CD29lowCD24+CD61-), and extract total RNA for cDNA microarray analysis
Project description:We used a mouse strain in which one Tbx3 gene was replaced with the yellow fluorescent protein variant Venus. Luminal cells had either very high Tbx3 promoter activity or not at all. We performed an expression analysis on luminal mammary epithelial cells sorted based on their Venus expression (reporting Tbx3 promoter activity) to investigate the difference between these two cell populations. Mammary epithelial cells from 3 Tbx3-Venus-KI adult virgin female mice (FVB background) were pooled and luminal cells were sorted into a Venus-hi and a Venus-neg sample. There were no repeats for this study.
Project description:Identification and transcriptome analysis of mammary stem cells (MaSC) are important steps toward understanding the molecular and cellular bases of mammary epithelial growth, homeostasis and tissue repair. We identified MaSC based upon their ability to retain bromodeoxyuridine (BrdU) for an extended period. Using laser microdissection, we isolated four categories of cells from the mammary epithelium of female bovine calves. These categories included label retaining epithelial cells (LREC) from the basal layer (LRECb), basal control cells (ECb), LREC from embedded layers (LRECe) and embedded control cells (ECe). Microarray analysis revealed 592 genes that were differentially expressed between LRECb and ECb, and 110 genes between LRECe and ECe. Our analysis supported classification of LRECb as MaSC and LRECe as progenitor cells. Enriched expression of genes in LRECb were associated with stem cell attributes and identified enrichment of Wnt, Notch and MAPK pathways of self renewal and proliferation. Genes expressed in LRECe revealed retention of some stem-like properties along with up-regulation of differentiation factors and the Notch pathway involved in lineage commitment. The basal epithelium provided for the stem cell niche, characterized as a microenvironment containing numerous survival and proliferation factors, growth suppressors and chromatin modifiers in balance state. We conclude that BrdU label retention identifies stem and progenitor cells, wherein MaSC are located in the basal epithelial layer and committed progenitor cells are localized in more apical layers. Results provide novel candidate markers for bovine MaSC with potential applicability to the study of MaSC in other species. Five Holstein heifers were injected with bromodeoxyuridine (BrdU) for five consecutive days and sacrificed 45 days later, at which time mammary samples were obtained and processed. Cryosections were prepared and immunostained to detect epithelial cells that retained BrdU label (LREC). Four classes of cells were excised by laser microdissection, which included LREC and control cells in the basal and in the suprabasal layers of the mammary epithelium. For each cell type, cells were lysed, RNA was reverse transcribed and cDNA amplified for microarray analysis. Twenty microarrays were utilized for sample hybridization and another array for hybridization of amplified cDNA from a water blank.