scholarly journals Altered mammary epithelial development, pattern formation and involution in transgenic mice expressing the EphB4 receptor tyrosine kinase

2002 ◽  
Vol 115 (1) ◽  
pp. 25-37
Author(s):  
Nadia Munarini ◽  
Richard Jäger ◽  
Susanne Abderhalden ◽  
Gisela Zuercher ◽  
Valeria Rohrbach ◽  
...  
Keyword(s):  
Mammary Gland ◽  
Transgenic Mice ◽  
Apoptotic Cell ◽  
Mammary Epithelium ◽  
Transgenic Animals ◽  
Mammary Glands ◽  
Mouse Mammary Gland ◽  
Mammary Epithelial ◽  
Cellular Growth ◽  
Mmtv Ltr

We have previously documented the cell-type-specific and hormone-dependent expression of the EphB4 receptor in the mouse mammary gland. To investigate its role in the biology of the mammary gland, we have established transgenic mice bearing the EphB4 receptor under the control of the MMTV-LTR promoter, which represents the first transgenic mouse model to investigate the effect(s) of unscheduled expression of EphB4 in adult organisms. Transgene expression in the mammary epithelium was induced at puberty, increased during pregnancy, culminated at early lactation and persisted until day three of post-lactational involution. In contrast, expression of the endogenous EphB4 gene is downregulated during pregnancy, is essentially absent during lactation and is re-induced after day three of post-lactational involution. The unscheduled expression of EphB4 led to a delayed development of the mammary epithelium at puberty and during pregnancy. During pregnancy, less lobules were formed, these however exhibited more numerous but smaller alveolar units. Transgenic mammary glands were characterized by a fragile, irregular morphology at lactation; however, sufficient functionality was maintained to nourish the young. Transgenic mammary glands exhibited untimely epithelial apoptotic cell death during pregnancy and abnormal epithelial DNA synthesis at early post-lactational involution, indicating a disturbed response to proliferative/apoptotic signals. Mammary tumours were not observed in the EphB4 transgenic animals; however, in double transgenic animals expressing both EphB4 and the neuT genes, tumour appearance was significantly accelerated and, in contrast to neuT-only animals, metastases were observed in the lung. These results implicate EphB4 in the regulation of tissue architecture, cellular growth response and establishment of the invasive phenotype in the adult mammary gland.

scholarly journals Prolactin inhibits cell loss and decreases matrix metalloproteinase expression in the involuting mouse mammary gland but fails to prevent cell loss in the mammary glands of mice expressing IGFBP-5 as a mammary transgene

2006 ◽  
Vol 36 (3) ◽  
pp. 435-448 ◽  
Author(s):  
D J Flint ◽  
M Boutinaud ◽  
C B A Whitelaw ◽  
G J Allan ◽  
A F Kolb
Keyword(s):  
Mammary Gland ◽  
Transgenic Mice ◽  
Mammary Epithelium ◽  
Transgenic Animals ◽  
Cell Loss ◽  
Mouse Mammary Gland ◽  
Luciferase Reporter ◽  
Wild Type ◽  
Luciferase Reporter Gene ◽  
Gland Weight

Insulin-like growth factor-binding protein 5 (IGFBP-5) mediates involution of the mammary gland. The decrease in DNA content and mammary gland weight which accompanies involution was inhibited by prolactin (PRL) in wild-type but not transgenic mice expressing IGFBP-5. Phospho-STAT5 protein levels were significantly lower in IGFBP-5 transgenic mice during lactation suggesting that IGFBP-5 antagonises PRL signalling in the mammary epithelium. In contrast, phospho-STAT3 levels increased during involution to a similar extent in both wild-type and transgenic mice and were unaffected by PRL. PRL inhibited gene expression of matrix metalloproteinases (MMPs) 3 and 12 but not tissue plasminogen activator or plasmin in wild-type and transgenic animals. The effects of PRL on MMPs appear to be indirect since PRL failed to inhibit MMP-3, -7 or -12 expression in HC-11 cells or in a co-transfection including an activated PRL receptor, STAT5 and a MMP-3-luciferase reporter gene. PRL is a potent inhibitor, both of cell death, an effect which is suppressed by IGFBP-5, and of MMP expression, which is independent of the actions of IGFBP-5.

Differential expression of the growth hormone receptor and growth hormone-binding protein in epithelia and stroma of the mouse mammary gland at various physiological stages

1999 ◽  
Vol 161 (1) ◽  
pp. 77-87 ◽  
Author(s):  
YN Ilkbahar ◽  
G Thordarson ◽  
IG Camarillo ◽  
F Talamantes
Keyword(s):  
Growth Hormone ◽  
Mammary Gland ◽  
Epithelial Cells ◽  
Growth Hormone Receptor ◽  
Mammary Epithelial Cells ◽  
Late Pregnancy ◽  
Mammary Glands ◽  
Mouse Mammary Gland ◽  
Mammary Epithelial ◽  
Mrna Levels

Increasing evidence suggests that GH is important in normal mammary gland development. To investigate this further, we studied the distribution and levels of growth hormone receptor (GHR) and GH-binding protein (GHBP) in the mouse mammary gland. At three weeks of age, the epithelial component of the right fourth inguinal mammary gland of female mice was removed. These animals were then either maintained as virgins until they were killed or they were mated. One group of the mated mice was killed on day 18 of pregnancy and the remaining mated animals were allowed to carry their pups until term and were killed on day 6 of lactation. At the time of death, both the intact left and the de-epithelialized right mammary glands were collected from all three groups. Some of the intact glands served as a source of epithelial cells, free of stroma. The mRNA levels for GHR and GHBP were measured in intact glands, epithelia-cleared fat pads, and isolated mammary epithelial cells. GHR and GHBP mRNAs were expressed in both the mammary epithelium and stroma. However, the levels of both GHR and GHBP mRNAs were significantly higher in the stroma as compared with the epithelium component. This increase for both mRNAs was from 3- to 12-fold at each physiological state examined. In the intact gland, both GHR and GHBP transcripts were highest in virgins, declined during late pregnancy, and the lowest levels were found in the lactating gland. GHBP and GHR protein concentrations were also assessed in intact glands and epithelia-free fat pads. Similar to the mRNAs, GHR and GHBP protein levels (means+/-s.e.m.) in intact glands were highest in virgin mice (0.891+/-0.15 pmoles/mg protein and 0.136+/-0.26 pmoles/mg protein respectively), declined during late pregnancy (0. 354+/-0.111 pmoles/mg protein and 0.178+/-0.039 pmoles/mg protein respectively), and were lowest during lactation (0.096+0.037 pmoles/mg protein and 0.017+0.006 pmoles/mg protein respectively). Immunocytochemistry utilizing specific antisera against mouse (m) GHR and mGHBP revealed that the two proteins are localized to both the stroma and parenchyma of mouse mammary glands, with similar patterns of immunostaining throughout the different physiological stages analyzed. GHR immunolocalized to the plasma membrane and cytosol of mammary epithelial cells and adipocytes, whereas the GHBP immunostaining was nuclear and cytosolic. In conclusion, we report here that GHR and GHBP mRNAs and proteins are expressed in both the epithelium and the stroma of mammary glands of virgin, pregnant, and lactating mice. In intact glands, GHR and GHBP proteins, as well as their transcripts are higher in abundance in virgin relative to lactating mice. At all physiological stages, GHR and GHBP mRNA levels are higher in the stroma compared with the parenchyma. These findings indicate that the actions of GH in the mammary gland are both direct through its binding to the epithelia, and indirect by binding to the stroma and stimulation of IGF-I production which, in turn, affects mammary epithelial development.

scholarly journals Insulin-like growth factor binding protein-5 (IGFBP-5) induces premature cell death in the mammary glands of transgenic mice

Development ◽  
2002 ◽  
Vol 129 (19) ◽  
pp. 4547-4557 ◽  
Author(s):  
Elizabeth Tonner ◽  
Michael C. Barber ◽  
Gordon J. Allan ◽  
James Beattie ◽  
John Webster ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Cell Death ◽  
Mammary Gland ◽  
Transgenic Mice ◽  
Dna Content ◽  
Caspase 3 ◽  
Transgenic Animals ◽  
Mammary Glands ◽  
Mammary Development ◽  
Igf I

We have previously demonstrated that IGFBP-5 production by mammary epithelial cells increases dramatically during involution of the mammary gland. To demonstrate a causal relationship between IGFBP-5 and cell death we created transgenic mice expressing IGFBP-5 in the mammary gland using a mammary-specific promoter, β-lactoglobulin. DNA content in the mammary glands of transgenic mice was decreased as early as day 10 of pregnancy. Histological analysis indicated reduced numbers of alveolar end buds, with decreased ductal branching. Transgenic dams produced IGFBP-5 in their milk at concentrations similar to those achieved at the end of normal lactation. Mammary cell number and milk synthesis were both decreased by approximately 50% during the first 10 days of lactation. BrdU labelling was decreased, whereas DNA ladders were increased in transgenic animals on day 1 of lactation. On day 2 postpartum, the epithelial invasion of the mammary fat pad was clearly impaired in transgenic animals. The concentrations of the pro-apoptotic molecule caspase-3 and of plasmin were both increased in transgenic animals whilst the concentrations of 2 prosurvival molecules Bcl-2 and Bcl-xLwere both decreased. In order to examine whether IGFBP-5 acts by inhibiting the survival effect of IGF-I we examined IGF receptor phosphorylation and Akt phosphorylation and showed that both were inhibited. We attempted to “rescue” the transgenic phenotype by using growth hormone to increase endogenous IGF-I concentrations or by implanting minipumps delivering an IGF-1 analogue, R3-IGF-1, which binds weakly to IGFBP-5. Growth hormone treatment failed to affect mammary development suggesting that increased concentrations of endogenous IGF-1 are insufficient to overcome the high concentrations of IGFBP-5 produced by these transgenic animals. In contrast mammary development (gland weight and DNA content) was normalised by R3-IGF-I although milk production was only partially restored. This is the first demonstration that over-expression of IGFBP-5 can lead to; impaired mammary development, increased expression of the pro-apoptotic molecule caspase-3, increased plasmin generation and decreased expression of pro-survival molecules of the Bcl-2 family. It clearly demonstrates that IGF-I is an important developmental/survival factor for the mammary gland and, furthermore, this cell death programme may be utilised in a wide variety of tissues.

scholarly journals Local Insulin-Like Growth Factor-II Mediates Prolactin-Induced Mammary Gland Development

2003 ◽  
Vol 17 (3) ◽  
pp. 460-471 ◽  
Author(s):  
Russell C. Hovey ◽  
Jessica Harris ◽  
Darryl L. Hadsell ◽  
Adrian V. Lee ◽  
Christopher J. Ormandy ◽  
...  
Keyword(s):  
Mammary Gland ◽  
Early Pregnancy ◽  
Insulin Receptors ◽  
Mammary Glands ◽  
Mouse Mammary Gland ◽  
Mammary Epithelial ◽  
Receptor Expression ◽  
Mammary Tissue ◽  
Alveolar Development

Abstract Prolactin (PRL) is a major determinant of mammary epithelial cell proliferation during alveolar development in sexually mature and pregnant mice. To date, it has not been clear whether PRL effects these responses alone or by also invoking the action of autocrine/paracrine growth factors. In this study, we provide evidence that part of the effect of PRL on mammary gland growth is mediated by IGF-II. During sexual maturity and in early pregnancy, the level of IGF-II mRNA in the mammary gland was increased concurrent with increased PRL receptor expression. The level of IGF-II mRNA was reduced in mammary tissue from PRL receptor−/− mice during early pregnancy, and explants of mouse mammary gland and HC11 mammary epithelial cells both increased their expression of IGF-II after exposure to PRL in vitro. These findings coincided with the demonstration that IGF-II stimulated alveolar development in mammary glands in whole organ culture. PRL was most efficacious in stimulating IGF-II gene transcription from promoter 3 of the mouse IGF-II gene in vitro. Insight into the mechanism by which PRL induced IGF-II expression was provided by the fact that it was blocked by the Jak2 inhibitor AG490 and the MAPK inhibitor PD98059. Finally, induction of insulin receptor substrate (IRS)-1 in the mammary glands of PRL-treated mice and induction of IRS-1 and IRS-2 after treatment with PRL plus progesterone indicates that these molecules are induced by PRL as potential signaling intermediates downstream from IGF-I/insulin receptors. Together, these data demonstrate a role for IGF-II as a mediator of PRL action in the mouse mammary gland during ductal branching and alveolar development.

scholarly journals Fine-tuning of Epithelial EGFR signals Supports Coordinated Mammary Gland Development

2020 ◽  
Author(s):  
Alexandr Samocha ◽  
Hanna M. Doh ◽  
Vaishnavi Sitarama ◽  
Quy H. Nguyen ◽  
Oghenekevwe Gbenedio ◽  
...  
Keyword(s):  
Mammary Gland ◽  
Mammary Epithelial Cells ◽  
Mammary Epithelium ◽  
Gene Signature ◽  
Mammary Epithelial ◽  
Fine Tuning ◽  
Basal Cells ◽  
Stem And Progenitor Cells

SummaryDuring puberty, robust morphogenesis occurs in the mammary gland; stem- and progenitor-cells develop into mature basal- and luminal-cells to form the ductal tree. The receptor signals that govern this process in mammary epithelial cells (MECs) are incompletely understood. The EGFR has been implicated and here we focused on EGFR’s downstream pathway component Rasgrp1. We find that Rasgrp1 dampens EGF-triggered signals in MECs. Biochemically and in vitro, Rasgrp1 perturbation results in increased EGFR-Ras-PI3K-AKT and mTORC1-S6 kinase signals, increased EGF-induced proliferation, and aberrant branching-capacity in 3D cultures. However, in vivo, Rasgrp1 perturbation results in delayed ductal tree maturation with shortened branches and reduced cellularity. Rasgrp1-deficient MEC organoids revealed lower frequencies of basal cells, the compartment that incorporates stem cells. Molecularly, EGF effectively counteracts Wnt signal-driven stem cell gene signature in organoids. Collectively, these studies demonstrate the need for fine-tuning of EGFR signals to properly instruct mammary epithelium during puberty.

scholarly journals Loss of vitamin D receptor signaling from the mammary epithelium or adipose tissue alters pubertal glandular development

2014 ◽  
Vol 307 (8) ◽  
pp. E674-E685 ◽  
Author(s):  
Abby L. Johnson ◽  
Glendon M. Zinser ◽  
Susan E. Waltz
Keyword(s):  
Vitamin D ◽  
Adipose Tissue ◽  
Mammary Gland ◽  
Epithelial Cell ◽  
Epithelial Cells ◽  
Mammary Epithelium ◽  
Mammary Development ◽  
Mammary Epithelial ◽  
Cell Type ◽  
Pubertal Mammary Development

Vitamin D3 receptor (VDR) signaling within the mammary gland regulates various postnatal stages of glandular development, including puberty, pregnancy, involution, and tumorigenesis. Previous studies have shown that vitamin D3 treatment induces cell-autonomous growth inhibition and differentiation of mammary epithelial cells in culture. Furthermore, mammary adipose tissue serves as a depot for vitamin D3 storage, and both epithelial cells and adipocytes are capable of bioactivating vitamin D3. Despite the pervasiveness of VDR in mammary tissue, individual contributions of epithelial cells and adipocytes, as well as the VDR-regulated cross-talk between these two cell types during pubertal mammary development, have yet to be investigated. To assess the cell-type specific effect of VDR signaling during pubertal mammary development, novel mouse models with mammary epithelial- or adipocyte-specific loss of VDR were generated. Interestingly, loss of VDR in either cellular compartment accelerated ductal morphogenesis with increased epithelial cell proliferation and decreased apoptosis within terminal end buds. Conversely, VDR signaling specifically in the mammary epithelium modulated hormone-induced alveolar growth, as ablation of VDR in this cell type resulted in precocious alveolar development. In examining cellular cross-talk ex vivo, we show that ligand-dependent VDR signaling in adipocytes significantly inhibits mammary epithelial cell growth in part through the vitamin D3-dependent production of the cytokine IL-6. Collectively, these studies delineate independent roles for vitamin D3-dependent VDR signaling in mammary adipocytes and epithelial cells in controlling pubertal mammary gland development.

scholarly journals Conditional Deletion of β-Catenin in Mammary Epithelial Cells of Ron Receptor, Mst1r, Overexpressing Mice Alters Mammary Tumorigenesis

Endocrinology ◽  
2012 ◽  
Vol 153 (6) ◽  
pp. 2735-2746 ◽  
Author(s):  
Purnima K. Wagh ◽  
Glendon M. Zinser ◽  
Jerilyn K. Gray ◽  
Archana Shrestha ◽  
Susan E. Waltz
Keyword(s):  
Epithelial Cells ◽  
Transgenic Mice ◽  
Target Genes ◽  
Mammary Epithelial Cells ◽  
Mammary Tumorigenesis ◽  
Mammary Epithelium ◽  
Mammary Tumors ◽  
Mammary Epithelial ◽  
Conditional Deletion ◽  
Ron Receptor

The Ron receptor tyrosine kinase (macrophage stimulating 1 receptor) is overexpressed in approximately 50% of human breast cancers. Transgenic mice overexpressing Ron in the mammary epithelium [mouse mammary tumor virus driven (MMTV)-Ron expressing mice] develop mammary tumors that exhibit up-regulation of β-catenin and β-catenin target genes. β-Catenin has been shown to be a mediator of mammary tumorigenesis in various breast cancer models, including downstream of Ron. However, the in vivo impact of a conditional loss of β-catenin downstream of Ron receptor overexpression on the onset, growth, turnover, and metastasis of mammary tumors has not been addressed. To determine the significance of β-catenin in the context of Ron overexpression, we conditionally deleted β-catenin in mammary epithelial cells of MMTV-Ron mice. Conditional deletion of β-catenin in the mammary epithelium, through the use of whey acidic protein (WAP)-Cre transgenic mice, significantly delayed the onset of mammary hyperplastic nodules, the presence of palpable mammary tumors, and ultimately decreased liver metastasis. β-Catenin loss in this model was also associated with decreased expression of cyclin D1. In total, these studies support an important role for β-catenin downstream of Ron receptor signaling during the development of mammary tumorigenesis.

Expression of bovine β-lactoglobulin transgenic mice

1999 ◽  
Vol 66 (2) ◽  
pp. 289-294 ◽  
Author(s):  
ALFONSO GUTIÉRREZ-ADÁN ◽  
ELIZABETH A. MAGA ◽  
ESMAIL BEHBOODI ◽  
JANICE S. CONRAD-BRINK ◽  
ANTHONY G. MACKINLAY ◽  
...  
Keyword(s):  
Mammary Gland ◽  
Transgenic Mice ◽  
Transgenic Animals ◽  
Milk Composition ◽  
Developmentally Regulated ◽  
Independent Manner ◽  
Milk Protein Genes ◽  
Dairy Animals ◽  
Foreign Proteins ◽  
Β Lactoglobulin

The use of transgenic animals to manipulate milk composition has considerable potential, both for the production of biomedical proteins and for the direct manipulation of milk composition for the improvement of dairy animals and their products (for reviews, see Wall et al. 1992; Yom & Bremel, 1993). Promoters from a number of milk protein genes from a variety of species have been tested for their ability to direct the expression of foreign proteins to the mammary gland (for review, see Maga & Murray, 1995).β-Lactoglobulin (β-lg) is the major whey protein produced in ruminant milk and is part of the normal milk composition of most mammals except humans and rodents (Pervaiz & Brew, 1985). It is expressed at high levels in the mammary gland and is developmentally regulated. Transgenic mice have been produced using the complete ovine (Simons et al. 1987; Shani et al. 1992) and caprine (Ibañez et al. 1997) β-lg genes. In general, high levels of expression were obtained with the ovine β-lg gene, and expression was also seen in a position-independent manner (Whitelaw et al. 1992). Lower levels of expression were reported using the caprine β-lg gene. Here we report the production of transgenic mice using the bovine β-lg gene. We describe high expression, position-dependent, and copy number-related expression of bovine β-lg protein in the milk of six lines of transgenic mice.

scholarly journals The differential actions of cortisol on the synthesis and turnover of alpha-lactalbumin and casein and on accumulation of their mRNA in mouse mammary gland in organ culture

1983 ◽  
Vol 212 (2) ◽  
pp. 507-515 ◽  
Author(s):  
Y Nagamatsu ◽  
T Oka
Keyword(s):  
Mammary Gland ◽  
Marked Decrease ◽  
Milk Proteins ◽  
Mammary Glands ◽  
Mouse Mammary Gland ◽  
Marked Enhancement ◽  
Pregnant Mice ◽  
Translatable Mrna ◽  
Casein Synthesis ◽  
Alpha Lactalbumin

Cortisol was previously shown to exert different, concentration-dependent, effects on the accumulation of casein and alpha-lactalbumin in mammary glands from mid-pregnant mice cultured in the presence of insulin and prolactin [Ono & Oka (1980) Cell 19, 473-480]. The present study demonstrated that the addition of 30nM-cortisol to the medium containing insulin and prolactin resulted in a marked enhancement of the rate of synthesis of both alpha-lactalbumin and casein in cultured tissue. The addition of 3 microM-cortisol in combination with insulin and prolactin caused a marked decrease in the rate of alpha-lactalbumin synthesis, but increased casein synthesis substantially. Similar changes were also observed in the amount of translatable mRNA for alpha-lactalbumin and casein in mammary explants cultured with insulin, prolactin and the two concentrations of cortisol. The study of the turnover of the milk proteins in cultured explants showed that virtually all of the casein synthesized remained intact in tissue explants cultured with 3 microM cortisol, whereas about 45% of casein disappeared in 40h from explants cultured with 30nM-cortisol. In contrast, the two concentrations of cortisol did not differentially affect the disappearance of alpha-lactalbumin, which was about 55% in 40h. These results indicate that the concentration-dependent differential actions of cortisol on the accumulation of alpha-lactalbumin and casein are exerted through its effects on the rate of synthesis and turnover of the two proteins as well as on the accumulation of their mRNA species.

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