26
|
Frech MS, Torre KM, Robinson GW, Furth PA. Loss of cyclin D1 in concert with deregulated estrogen receptor alpha expression induces DNA damage response activation and interrupts mammary gland morphogenesis. Oncogene 2007; 27:3186-93. [PMID: 18071314 DOI: 10.1038/sj.onc.1210974] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
We have previously shown that increased and deregulated estrogen receptor alpha expression in the mammary gland leads to the development of proliferative disease and cancer. To address the importance of cyclin D1 in ERalpha-mediated mammary tumorigenesis, we crossed ERalpha-overexpressing mice with cyclin D1 knockout mice. Mammary gland morphogenesis was completely interrupted in the ERalpha-overexpressing cyclin D1-deficient triple transgenic mice. In addition to a highly significant reduction in mammary epithelial cell proliferation, cyclin E was upregulated resulting in DNA damage checkpoint activation and apoptosis. This imbalance between proliferative and apoptotic rates in conjunction with remarkable structural defects and cellular disorganization in the terminal end buds interrupted ductal morphogenesis. Interestingly, the structure of the mammary fat pad was fundamentally altered by the consequences of overexpressing ERalpha in the epithelial cells in the absence of cyclin D1 illustrating how alterations in the epithelial compartment can impact surrounding stromal composition. Transplantation of embryonic ERalpha-overexpressing and cyclin D1-deficient mammary epithelium into the cleared fat pad of wild-type mice did not rescue the aberrant mammary gland phenotype indicating that it was intrinsic to the mammary epithelial cells. In conclusion, although cyclin D1 is not essential for proliferation of normal mammary epithelial cells, ERalpha-overexpressing cells are absolutely dependent on cyclin D1 for proliferation. This differential requirement for cyclin D1 in normal vs abnormal mammary epithelial cells supports the application of cyclin D1 inhibitors as therapeutic interventions in ERalpha-overexpressing breast cancers.
Collapse
|
27
|
Cui Y, Hosui A, Sun R, Shen K, Gavrilova O, Chen W, Cam MC, Gao B, Robinson GW, Hennighausen L. Loss of signal transducer and activator of transcription 5 leads to hepatosteatosis and impaired liver regeneration. Hepatology 2007; 46:504-13. [PMID: 17640041 DOI: 10.1002/hep.21713] [Citation(s) in RCA: 151] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
UNLABELLED Growth hormone controls many facets of a cell's biology through the transcription factors Stat5a and Stat5b (Stat5). However, whole body deletion of these genes from the mouse does not provide portentous information on cell-specific cytokine signaling. To explore liver-specific functions of Stat5, the entire Stat5 locus was deleted in hepatocytes using Cre-mediated recombination. Notably, Stat5-mutant mice developed fatty livers and displayed impaired proliferation of hepatocytes upon partial hepatectomy (PHx). Loss of Stat5 led to molecular consequences beyond the reduced expression of Stat5 target genes, such as those encoding suppressor of cytokine signaling 2 (SOCS2), Cish, and insulin-like growth factor 1 (IGF-1). In particular, circulating growth hormone levels were increased and correlated with insulin resistance and increased insulin levels. Aberrant growth hormone (GH)-induced activation of the transcription factors Stat1 and Stat3 was observed in mutant livers. To test whether some of the defects observed in liver-specific Stat5 deficient mice were due to aberrant Stat1 expression and activation, we generated Stat1(-/-) mice with a hepatocyte-specific deletion of Stat5. Concomitant loss of both Stat5 and Stat1 restored cell proliferation upon PHx but did not reverse fatty liver development. Thus the molecular underpinnings of some defects observed in the absence of Stat5 are the consequence of a deregulated activation of other signal transducers and activators of transcription (STAT) family members. CONCLUSION Aberrant cytokine-Stat5 signaling in hepatocytes alters their physiology through increased activity of Stat1 and Stat3. Such cross-talk between different pathways could add to the complexity of syndromes observed in disease.
Collapse
|
28
|
Robinson GW, Pacher-Zavisin M, Zhu BM, Yoshimura A, Hennighausen L. Socs 3 modulates the activity of the transcription factor Stat3 in mammary tissue and controls alveolar homeostasis. Dev Dyn 2007; 236:654-61. [PMID: 17205581 DOI: 10.1002/dvdy.21058] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Signal transducer and activator of transcription 5 and 3 (Stat5 and Stat3) control pregnancy-mediated mammary development and involution-dependent remodeling, respectively. Suppressor of cytokine signaling 3 (Socs3) has been implicated in the modulation of both Stat3 and Stat5 activity. To explore the biology of Socs3 in mammary tissue, the gene was deleted using Cre-mediated recombination. Deletion of the Socs3 gene from mammary stem or early progenitor cells did not grossly alter pregnancy-mediated mammary development but resulted in impaired lactation due to attenuated proliferation. Loss of Socs3 from differentiated luminal cells did not interfere with glandular function during lactation, but resulted in accelerated tissue remodeling upon weaning. Loss of Socs3 led to enhanced and precocious Stat3 activation. Thus, Socs3 serves as a modulator of Stat3 activity to ensure controlled proliferation and apoptosis in pregnancy and involution, respectively.
Collapse
|
29
|
Garin É, Lemieux M, Coulombe Y, Robinson GW, Jeannotte L. Stromal Hoxa5 function controls the growth and differentiation of mammary alveolar epithelium. Dev Dyn 2007. [DOI: 10.1002/dvdy.21224] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
|
30
|
Lee JY, Gavrilova O, Davani B, Robinson GW, Hennighausen L. The transcription factors Stat5a/b are not required for islet development but modulate pancreatic beta-cell physiology upon aging. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2007; 1773:1455-61. [PMID: 17599554 PMCID: PMC2695665 DOI: 10.1016/j.bbamcr.2007.05.010] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2007] [Revised: 05/03/2007] [Accepted: 05/03/2007] [Indexed: 10/23/2022]
Abstract
In insulinoma cell lines proliferation and insulin gene transcription are stimulated by growth hormone and prolactin, which convey their signals through the transcription factors Stat5a and 5b (referred to as Stat5). However, the contribution of Stat5 to the physiology of beta-cells in vivo could not be assessed directly since Stat5-null mice die perinataly. To explore the physiological role of Stat5 in the mouse, the corresponding gene locus targeted with loxP sites was inactivated in beta-cells using two lines of Cre recombinase expressing transgenic mice. While the RIP-Cre transgene is active in pancreatic beta-cells and the hypothalamus, the Pdx1-Cre transgene is active in precursor cells of the endocrine and exocrine pancreas. Mice carrying two floxed Stat5alleles and a RIP-Cre transgene developed mild obesity, were hyperglycemic and exhibited impaired glucose tolerance. Since RIP-Cre transgenic mice by themselves display some glucose intolerance, the significance of these data is unclear. In contrast, mice, in which the Stat5 locus had been deleted with the Pdx1-Cre transgene, developed functional islets and were glucose tolerant. Mild glucose intolerance occurred with age. We conclude that Stat5 is not essential for islet development but may modulate beta-cell function.
Collapse
|
31
|
Yao Z, Kanno Y, Kerenyi M, Stephens G, Durant L, Watford WT, Laurence A, Robinson GW, Shevach EM, Moriggl R, Hennighausen L, Wu C, O'Shea JJ. Nonredundant roles for Stat5a/b in directly regulating Foxp3. Blood 2007; 109:4368-75. [PMID: 17227828 PMCID: PMC1885496 DOI: 10.1182/blood-2006-11-055756] [Citation(s) in RCA: 446] [Impact Index Per Article: 26.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2006] [Accepted: 01/08/2007] [Indexed: 12/12/2022] Open
Abstract
Stats (signal transducers and activators of transcription) regulate multiple aspects of T-cell fate. T regulatory (Treg) cells are a critical subset that limits immune responses, but the relative importance of Stat5a/b versus Stat3 for Treg cell development has been contentious. We observed that peripheral CD25(+)CD4(+) T cells were reduced in Stat5(DeltaN) mice; however, the levels of Foxp3, a transcription factor that is critical for Treg cells, were normal in splenic CD4(+) T cells even though they were reduced in the thymus. In contrast, complete deletion of Stat5a/b (Stat5(-/-)) resulted in dramatic reduction in CD25- or Foxp3-expressing CD4(+) T cells. An intrinsic requirement was demonstrated by reduction of Stat5a/b in CD4-expressing cells and by stem cell transplantation using Stat5(-/-) fetal liver cells. Stat5a/b were also required for optimal induction of Foxp3 in vitro and bound directly to the Foxp3 gene. Reduction of Stat3 in T cells did not reduce the numbers of Treg cells in the thymus or spleen; however, Stat3 was required for IL-6-dependent down-regulation of Foxp3. Therefore, we conclude that Stat5a/b have an essential, nonredundant role in regulating Treg cells, and that Stat3 and Stat5a/b appear to have opposing roles in the regulation of Foxp3.
Collapse
|
32
|
Hens JR, Dann P, Zhang JP, Harris S, Robinson GW, Wysolmerski J. BMP4 and PTHrP interact to stimulate ductal outgrowth during embryonic mammary development and to inhibit hair follicle induction. Development 2007; 134:1221-30. [PMID: 17301089 DOI: 10.1242/dev.000182] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The mammary glands develop initially as buds arising from the ventral embryonic epidermis. Recent work has shed light on signaling pathways leading to the patterning and formation of the mammary placodes and buds in mouse embryos. Relatively little is known of the signaling pathways that initiate branching morphogenesis and the formation of the ducts from the embryonic buds. Previous studies have shown that parathyroid hormone-related protein (PTHrP; also known as parathyroid hormone-like peptide, Pthlh) is produced by mammary epithelial cells and acts on surrounding mesenchymal cells to promote their differentiation into a mammary-specific dense mesenchyme. As a result of PTHrP signaling, the mammary mesenchyme supports mammary epithelial cell fate, initiates ductal development and patterns the overlying nipple sheath. In this report, we demonstrate that PTHrP acts, in part, by sensitizing mesenchymal cells to BMP signaling. PTHrP upregulates BMP receptor 1A expression in the mammary mesenchyme, enabling it to respond to BMP4, which is expressed within mesenchymal cells underlying the ventral epidermis during mammary bud formation. We demonstrate that BMP signaling is important for outgrowth of normal mammary buds and that BMP4 can rescue outgrowth of PTHrP(-/-) mammary buds. In addition, the combination of PTHrP and BMP signaling is responsible for upregulating Msx2 gene expression within the mammary mesenchyme, and disruption of the Msx2 gene rescues the induction of hair follicles on the ventral surface of mice overexpressing PTHrP in keratinocytes (K14-PTHrP). Our data suggest that PTHrP signaling sensitizes the mammary mesenchyme to the actions of BMP4, triggering outgrowth of the mammary buds and inducing MSX2 expression, which, in turn, leads to lateral inhibition of hair follicle formation within the developing nipple sheath.
Collapse
|
33
|
Garin E, Lemieux M, Coulombe Y, Robinson GW, Jeannotte L. Stromal Hoxa5 function controls the growth and differentiation of mammary alveolar epithelium. Dev Dyn 2006; 235:1858-71. [PMID: 16607641 DOI: 10.1002/dvdy.20822] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Recent progress has enlightened the involvement of Hox genes in organogenesis. Several Hox genes are expressed in normal and neoplastic mammary glands. Using Hoxa5 mutant mice, we showed that Hoxa5-/- females present nursing defects. Characterization of the Hoxa5-/- mammary gland phenotype reveals changes in proliferation and differentiation of the epithelium of nulliparous and pregnant Hoxa5-/- females that precede the abnormal secretory activity at parturition. These defects likely underlie the incapacity of Hoxa5-/- dams to properly feed their pups. Hoxa5 expression is restricted to the mammary stroma at specific stages of mammary gland development. The loss of Hoxa5 function causes accelerated lobuloalveolar epithelium development, a phenotype that can be rescued upon grafting of mutant mammary epithelium into wild-type fat pads. Conversely, reciprocal grafting experiments demonstrate that Hoxa5-/- stroma cannot support normal proliferation of wild-type mammary epithelium. These data establish the essential contribution of Hoxa5 to mammary epithelium instruction by means of mesenchymal-epithelial crosstalk.
Collapse
|
34
|
Sun Y, Boyd K, Xu W, Ma J, Jackson CW, Fu A, Shillingford JM, Robinson GW, Hennighausen L, Hitzler JK, Ma Z, Morris SW. Acute myeloid leukemia-associated Mkl1 (Mrtf-a) is a key regulator of mammary gland function. Mol Cell Biol 2006; 26:5809-26. [PMID: 16847333 PMCID: PMC1592762 DOI: 10.1128/mcb.00024-06] [Citation(s) in RCA: 136] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Transcription of immediate-early genes--as well as multiple genes affecting muscle function, cytoskeletal integrity, apoptosis control, and wound healing/angiogenesis--is regulated by serum response factor (Srf). Extracellular signals regulate Srf in part via a pathway involving megakaryoblastic leukemia 1 (Mkl1, also known as myocardin-related transcription factor A [Mrtf-a]), which coactivates Srf-responsive genes downstream of Rho GTPases. Here we investigate Mkl1 function using gene targeting and show the protein to be essential for the physiologic preparation of the mammary gland during pregnancy and the maintenance of lactation. Lack of Mkl1 causes premature involution and impairs expression of Srf-dependent genes in the mammary myoepithelial cells, which control milk ejection following oxytocin-induced contraction. Despite the importance of Srf in multiple transcriptional pathways and widespread Mkl1 expression, the spectrum of abnormalities associated with Mkl1 absence appears surprisingly restricted.
Collapse
MESH Headings
- Animals
- Animals, Newborn
- Apoptosis
- Child
- Failure to Thrive
- Female
- Gene Expression Profiling
- Gene Expression Regulation
- Gene Targeting
- Heart/anatomy & histology
- Heart/embryology
- Humans
- Infant
- Lactation/physiology
- Leukemia, Megakaryoblastic, Acute
- Male
- Mammary Glands, Animal/abnormalities
- Mammary Glands, Animal/anatomy & histology
- Mammary Glands, Animal/physiology
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Milk
- Myocytes, Cardiac/pathology
- Myocytes, Cardiac/ultrastructure
- Oligonucleotide Array Sequence Analysis
- Oxytocin/metabolism
- Pregnancy
- Prolactin/metabolism
- STAT3 Transcription Factor
- Serum Response Factor/genetics
- Serum Response Factor/metabolism
- Trans-Activators/genetics
- Trans-Activators/metabolism
Collapse
|
35
|
|
36
|
Buono KD, Robinson GW, Martin C, Shi S, Stanley P, Tanigaki K, Honjo T, Hennighausen L. The canonical Notch/RBP-J signaling pathway controls the balance of cell lineages in mammary epithelium during pregnancy. Dev Biol 2006; 293:565-80. [PMID: 16581056 DOI: 10.1016/j.ydbio.2006.02.043] [Citation(s) in RCA: 111] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2006] [Revised: 02/16/2006] [Accepted: 02/18/2006] [Indexed: 11/30/2022]
Abstract
Mammary alveoli are composed of luminal (secretory) and basal (myoepithelial) cells, which are descendants of a common stem cell. This study addressed the role of RBP-J-dependent Notch signaling in the formation, maintenance and cellular composition of alveoli during pregnancy. For this purpose, the genes encoding RBP-J, the shared transcriptional mediator of Notch receptors, and Pofut1, a fucosyltransferase required for the activity of Notch receptors, were deleted in mammary progenitor cells in the mouse using Cre-mediated recombination. Loss of RBP-J and Pofut1 led to an accumulation of basal cell clusters characterized by the presence of cytokeratins (K5) and K14 and smooth muscle actin (SMA) during pregnancy. Hormonal stimulation of mutant tissue induced the expression of the basal cell transcription factor p63 in luminal cells and excessive proliferation of basal cells. A transient enrichment of K6-positive luminal cells was observed upon hormonal treatment suggesting a temporary arrest at an immature stage prior to transdifferentiation and expansion as basal cells. Despite the extensive proliferation of RBP-J-null basal cells during pregnancy, hormonal withdrawal during involution resulted in complete remodeling and the restoration of normal tissue architecture. We propose that the Notch-RBP-J pathway regulates alveolar development during pregnancy by maintaining luminal cell fate and preventing uncontrolled basal cell proliferation.
Collapse
|
37
|
Abstract
Unique developmental features during puberty, pregnancy, lactation and post-lactation make the mammary gland a prime object to explore genetic circuits that control the specification, proliferation, differentiation, survival and death of cells. Steroids and simple peptide hormones initiate and carry out complex developmental programmes, and reverse genetics has been used to define the underlying mechanistic connections.
Collapse
|
38
|
Le Provost F, Miyoshi K, Vilotte JL, Bierie B, Robinson GW, Hennighausen L. SOCS3 promotes apoptosis of mammary differentiated cells. Biochem Biophys Res Commun 2005; 338:1696-701. [PMID: 16289036 DOI: 10.1016/j.bbrc.2005.10.138] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2005] [Accepted: 10/21/2005] [Indexed: 10/25/2022]
Abstract
Growth and function of the mammary gland is regulated by cytokines and modulated by suppressor of cytokine signalling (SOCS) proteins. In vitro experiments demonstrated that SOCS3 can inhibit PRL induction of milk protein gene expression and STAT5 activation. We explored the SOCS3 expression pattern during mouse mammary development and its regulation by PRL and GH in wild-type and STAT5a-null mammary tissue. Our results suggest that, in vivo, PRL stimulates SOCS3 expression in stromal adipocytes, independently of STAT5a stimulation. In mammary epithelial cells, SOCS3 expression appears to be related to STAT3 activation. Together, our results are consistent with a role of SOCS3 in the mammary gland by promoting apoptosis of differentiated cells (adipocytes during gestation and epithelial cells during involution).
Collapse
|
39
|
Cui Y, Riedlinger G, Miyoshi K, Tang W, Li C, Deng CX, Robinson GW, Hennighausen L. Inactivation of Stat5 in mouse mammary epithelium during pregnancy reveals distinct functions in cell proliferation, survival, and differentiation. Mol Cell Biol 2004; 24:8037-47. [PMID: 15340066 PMCID: PMC515028 DOI: 10.1128/mcb.24.18.8037-8047.2004] [Citation(s) in RCA: 393] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
This study explored the functions of the signal transducers and activators of transcription 5a and 5b (referred to as Stat5 here) during different stages of mouse mammary gland development by using conditional gene inactivation. Mammary gland morphogenesis includes cell specification, proliferation and differentiation during pregnancy, cell survival and maintenance of differentiation throughout lactation, and cell death during involution. Stat5 is activated by prolactin, and its presence is mandatory for the proliferation and differentiation of mammary epithelium during pregnancy. To address the question of whether Stat5 is also necessary for the maintenance and survival of the differentiated epithelium, the two genes were deleted at different time points. The 110-kb Stat5 locus in the mouse was bracketed with loxP sites, and its deletion was accomplished by using two Cre-expressing transgenic lines. Loss of Stat5 prior to pregnancy prevented epithelial proliferation and differentiation. Deletion of Stat5 during pregnancy, after mammary epithelium had entered Stat5-mediated differentiation, resulted in premature cell death, indicating that at this stage epithelial cell proliferation, differentiation, and survival require Stat5.
Collapse
|
40
|
Zhao L, Hart S, Cheng J, Melenhorst JJ, Bierie B, Ernst M, Stewart C, Schaper F, Heinrich PC, Ullrich A, Robinson GW, Hennighausen L. Mammary gland remodeling depends on gp130 signaling through Stat3 and MAPK. J Biol Chem 2004; 279:44093-100. [PMID: 15292206 DOI: 10.1074/jbc.m313131200] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The interleukin-6 (IL6) family of cytokines signals through the common receptor subunit gp130, and subsequently activates Stat3, MAPK, and PI3K. Stat3 controls cell death and tissue remodeling in the mouse mammary gland during involution, which is partially induced by IL6 and LIF. However, it is not clear whether Stat3 activation is mediated solely through the gp130 pathway or also through other receptors. This question was explored in mice carrying two distinct mutations in the gp130 gene; one that resulted in the complete ablation of gp130 and one that led to the loss of Stat3 binding sites (gp130Delta/Delta). Deletion of gp130 specifically from mammary epithelium resulted in a complete loss of Stat3 activity and resistance to tissue remodeling comparable to that seen in the absence of Stat3. A less profound delay of mammary tissue remodeling was observed in gp130Delta/Delta mice. Stat3 tyrosine and serine phosphorylation was still detected in these mice suggesting that Stat3 activation could be the result of gp130 interfacing with other receptors. Experiments in primary mammary epithelial cells and transfected COS-7 cells revealed a p44/42 MAPK and EGFR-dependent Stat3 activation. Moreover, the gp130-dependent EGFR activation was independent of EGF ligands, suggesting a cytoplasmic interaction and cross-talk between these two receptors. These experiments establish that two distinct Stat3 signaling pathways emanating from gp130 are utilized in mammary tissue.
Collapse
|
41
|
Bry C, Maass K, Miyoshi K, Willecke K, Ott T, Robinson GW, Hennighausen L. Loss of connexin 26 in mammary epithelium during early but not during late pregnancy results in unscheduled apoptosis and impaired development. Dev Biol 2004; 267:418-29. [PMID: 15013803 DOI: 10.1016/j.ydbio.2003.11.022] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2003] [Revised: 11/07/2003] [Accepted: 11/24/2003] [Indexed: 11/25/2022]
Abstract
Gap junctions are intercellular channels that are formed by the protein family of connexins (Cxs). In mammary tissue, Cx26 and Cx32 are present in the secretory epithelium and Cx43 is localized in the myoepithelium. The expression of Cx26 and Cx32 is induced during pregnancy and lactation, respectively, thus suggesting unique roles for them in the functional development of the gland. The requirement for these connexins was explored using several strains of genetically altered mice: mice with an inactivated Cx32 gene, mice in which the Cx43 gene had been replaced with the Cx32 gene (Cx43KI32 mice) and mice in which the Cx26 gene was specifically ablated in mammary epithelium at different stages of development using Cre-loxP-based recombination. Normal mammary development was obtained in Cx32-null mice and in Cx43KI32 mammary tissue. In contrast, loss of Cx26 in mammary epithelium before puberty resulted in abrogated lobulo-alveolar development and increased cell death during pregnancy, which was accompanied by impaired lactation. Loss of Cx26 in mammary epithelium during the later part of pregnancy did not adversely interfere with functional mammary development. These results demonstrate that the presence of Cx26 is critical during early stages but not during the end of pregnancy when the tissue has completed functional differentiation. Cx26 is considered a tumor suppressor gene and Cx26-null mammary tissue was evaluated after five pregnancies. No hyperproliferation or hyperplasia was observed, suggesting that Cx26 does not function as a tumor suppressor.
Collapse
|
42
|
Robinson GW. Identification of signaling pathways in early mammary gland development by mouse genetics. Breast Cancer Res 2004; 6:105-8. [PMID: 15084230 PMCID: PMC400673 DOI: 10.1186/bcr776] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2004] [Accepted: 02/18/2004] [Indexed: 12/01/2022] Open
Abstract
The mammary gland develops as an appendage of the ectoderm. The prenatal stage of mammary development is hormone independent and is regulated by sequential and reciprocal signaling between the epithelium and the mesenchyme. A number of recent studies using human and mouse genetics, in particular targeted gene deletion and transgenic expression, have identified some of the signals that control specific steps in development. This process involves cell specification and proliferation, reciprocal tissue interactions and cell migration. Since some of these events are recapitulated during tumorigenesis, an understanding of these signaling pathways may contribute to the development of targeted therapies and novel drugs.
Collapse
|
43
|
Evarts JL, Rasweiler JJ, Behringer RR, Hennighausen L, Robinson GW. A morphological and immunohistochemical comparison of mammary tissues from the short-tailed fruit bat (Carollia perspicillata) and the mouse. Biol Reprod 2004; 70:1573-9. [PMID: 14749297 DOI: 10.1095/biolreprod.103.022988] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
In the present study, mammary tissues from the fruit bat (Carollia perspicillata) and mouse (Mus musculus) were compared using histological and immunohistochemical methods. Because the female bat exhibits greater reproductive similarities to humans, it might provide a useful animal model for studying mammary physiology and disease with relevance to our own species. In lactating and recently lactating specimens, bat tissue had significantly fewer adipocytes and more collagenous connective tissue compared to the mouse. The proteins Stat5a, keratin 5, Npt2b, and E-cadherin were all similarly localized in mouse and bat mammary tissues taken from lactating animals. The present study demonstrates that whereas the epithelial compartment and the presence of differentiation markers are conserved between the mouse and bat, differences exist in the stromal compartment.
Collapse
|
44
|
Bierie B, Nozawa M, Renou JP, Shillingford JM, Morgan F, Oka T, Taketo MM, Cardiff RD, Miyoshi K, Wagner KU, Robinson GW, Hennighausen L. Activation of beta-catenin in prostate epithelium induces hyperplasias and squamous transdifferentiation. Oncogene 2003; 22:3875-87. [PMID: 12813461 DOI: 10.1038/sj.onc.1206426] [Citation(s) in RCA: 107] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The Wnt/beta-catenin signaling pathway is critical for normal mammalian development, the specification of epidermal cells and neoplastic transformation of intestinal epithelium. However, precise molecular information regarding cell-specific responses to beta-catenin signaling has been limited. This question was addressed using a mouse model in which exon 3 of the beta-catenin gene was deleted in several cell types with loxP-mediated recombination utilizing a Cre transgene under control of the mouse mammary tumor virus-long terminal repeat (MMTV-LTR). The stabilization of beta-catenin in prostate epithelium resulted in hyperplasias and extensive transdifferentiation into epidermal-like structures, which expressed keratins 1 and 6, filaggrin, loricrin and involucrin. The cell-specific loss of NKCC1 protein and reduced nuclear Stat5a is further suggestive of a loss of prostate epithelial characteristics. In addition to the prostate, hyperplasias and squamous metaplasias were detected in epithelia of the epididymis, vas deferens, coagulating gland, preputial gland and salivary gland. However, and in contrast to a recent study, no lesions reminiscent of high-grade prostate intraepithelial neoplasia were detected. Since beta-catenin was activated in several cell types and impinged upon the viability of these mice, it was not possible to evaluate the cumulative effect over more than 3 months. To assess long-term consequences of beta-catenin activation, mutant and control prostate tissues were transplanted into the mammary fat pads of wild-type males. Notably, squamous metaplasias, intra-acinous hyperplasia and possible neoplastic transformation were observed after a total of 18 weeks of beta-catenin stimulation. This suggests that the transdifferentiation into squamous metaplasias is an early response of endoderm-derived cells to beta-catenin, and that the development of intra-acinous hyperplasias or neoplastic foci is a later event.
Collapse
|
45
|
Shillingford JM, Miyoshi K, Robinson GW, Bierie B, Cao Y, Karin M, Hennighausen L. Proteotyping of mammary tissue from transgenic and gene knockout mice with immunohistochemical markers: a tool to define developmental lesions. J Histochem Cytochem 2003; 51:555-65. [PMID: 12704203 DOI: 10.1177/002215540305100501] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Through the use of transgenic and gene knockout mice, several studies have identified specific genes required for the functional development of mammary epithelium. Although histological and milk protein gene analyses can provide useful information regarding functional differentiation, they are limited in their ability to precisely define the molecular lesions. For example, mice that carry a mutation in one of the subunits of the IkappaB kinase, IKKalpha, cannot lactate despite the presence of histologically normal alveolar compartment and the expression of milk protein genes. To further define and understand such lesions on a molecular level, we sought evidence for proteins that are differentially expressed during mammary gland development with a view to generating a tissue proteotype. Using database screens and immunohistochemical analyses, we have identified three proteins that exhibit distinct profiles. Here, using mouse models as test biological systems, we demonstrate the development and application of mammary tissue proteotyping and its use in the elucidation of specific developmental lesions. We propose that the technique of proteotyping will have wide applications in the analyses of defects in other mouse models.
Collapse
|
46
|
Kumaraswamy E, Carlson BA, Morgan F, Miyoshi K, Robinson GW, Su D, Wang S, Southon E, Tessarollo L, Lee BJ, Gladyshev VN, Hennighausen L, Hatfield DL. Selective removal of the selenocysteine tRNA [Ser]Sec gene (Trsp) in mouse mammary epithelium. Mol Cell Biol 2003; 23:1477-88. [PMID: 12588969 PMCID: PMC151713 DOI: 10.1128/mcb.23.5.1477-1488.2003] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Mice homozygous for an allele encoding the selenocysteine (Sec) tRNA [Ser]Sec gene (Trsp) flanked by loxP sites were generated. Cre recombinase-dependent removal of Trsp in these mice was lethal to embryos. To investigate the role of Trsp in mouse mammary epithelium, we deleted this gene by using transgenic mice carrying the Cre recombinase gene under control of the mouse mammary tumor virus (MMTV) long terminal repeat or the whey acidic protein promoter. While both promoters target Cre gene expression to mammary epithelium, MMTV-Cre is also expressed in spleen and skin. Sec tRNA [Ser]Sec amounts were reduced by more than 70% in mammary tissue with either transgene, while in skin and spleen, levels were reduced only with MMTV-Cre. The selenoprotein population was selectively affected with MMTV-Cre in breast and skin but not in the control tissue, kidney. Moreover, within affected tissues, expression of specific selenoproteins was regulated differently and often in a contrasting manner, with levels of Sep15 and the glutathione peroxidases GPx1 and GPx4 being substantially reduced. Expression of the tumor suppressor genes BRCA1 and p53 was also altered in a contrasting manner in MMTV-Cre mice, suggesting greater susceptibility to cancer and/or increased cell apoptosis. Thus, the conditional Trsp knockout mouse allows tissue-specific manipulation of Sec tRNA and selenoprotein expression, suggesting that this approach will provide a useful tool for studying the role of selenoproteins in health.
Collapse
MESH Headings
- Alleles
- Animals
- Blotting, Northern
- Blotting, Western
- Breast/metabolism
- Chromatography
- Crosses, Genetic
- Epithelium/metabolism
- Gene Deletion
- Genes, BRCA1
- Genes, p53/genetics
- Genetic Vectors
- Glutathione Peroxidase/metabolism
- Heterozygote
- Kidney/metabolism
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Mice, Transgenic
- Models, Genetic
- Phenotype
- Promoter Regions, Genetic
- Proteins/metabolism
- RNA, Transfer, Amino Acyl/genetics
- RNA, Transfer, Amino Acyl/metabolism
- Recombination, Genetic
- Selenoproteins
- Tissue Distribution
- Transgenes
Collapse
|
47
|
Miyoshi K, Meyer B, Gruss P, Cui Y, Renou JP, Morgan FV, Smith GH, Reichenstein M, Shani M, Hennighausen L, Robinson GW. Mammary epithelial cells are not able to undergo pregnancy-dependent differentiation in the absence of the helix-loop-helix inhibitor Id2. Mol Endocrinol 2002; 16:2892-901. [PMID: 12456807 DOI: 10.1210/me.2002-0128] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Mammary alveolar development during pregnancy is triggered by hormone signals. The prolactin receptor/Jak2/signal transducer and activator of transcription (Stat) 5 signal transduction pathway is the principal mediator of these cues and alveolar development is abrogated in its absence. The loss of the basic helix-loop-helix protein inhibitor of differentiation (Id)2 results in a similar defect. To investigate the role of Id2 in mammary epithelium, we performed structural and molecular analyses. Id2-null mammary epithelial cells were unable to form alveoli; the epithelial architecture was disorganized and dissimilar from early stages of alveologenesis in wild-type glands. The epithelial cells retained the ductal marker Na-K-Cl cotransporter (NKCC)1. Nuclear localization of Stat5a and down-regulation of NKCC1 was observed in some areas, indicating a limited response to pregnancy signals. The differentiation status of Id2-null tissue at term was further characterized with cDNA microarrays enriched in mammary specific sequences (mammochip). Some of the early differentiation markers for mammary epithelium were expressed in the Id2-null tissue, whereas genes that are expressed at later stages of pregnancy were not induced. From these results, we conclude that, in the absence of Id2, mammary epithelial development is arrested at an early stage of pregnancy.
Collapse
|
48
|
Gallego MI, Beachy PA, Hennighausen L, Robinson GW. Differential requirements for shh in mammary tissue and hair follicle morphogenesis. Dev Biol 2002; 249:131-9. [PMID: 12217324 DOI: 10.1006/dbio.2002.0761] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Sonic Hedgehog (Shh) is a secreted morphogen that directs patterning and cellular differentiation through binding to its receptor Patched (Ptc). It is required for the development of skin-derived organs, such as hair, whiskers, and teeth. The mammary gland is a skin-derived organ that develops mainly during adult life in which Shh is expressed from puberty to lactation. We have investigated the role of Shh in mammary gland morphogenesis and differentiation by two transplantation approaches. Since Shh-null fetuses die at late embryogenesis, we transplanted Shh-null mammary anlagen into cleared fat pads and under the renal capsule of wild type host mice. Pregnancy-mediated functional differentiation of Shh-null mammary epithelium was indistinguishable from wild type transplants, while hair follicles derived from cotransplanted skin only developed in wild type transplants. Transplants of Ihh-null anlagen also developed normally. To assess the molecular consequences of Shh deletion in mammary tissue, we compared mRNA levels of patched 1, a target gene of Hedgehog signaling, in Shh-null and wild type mammary epithelial transplants. No reduction of Ptc1 transcripts was observed in Shh-null mammary tissues. Our results demonstrate that neither Shh nor Ihh is required for mammary gland morphogenesis and functional differentiation, suggesting that the two members of the Hedgehog family may have redundant function in activating the Ptc1 signaling pathway during mammary gland development.
Collapse
|
49
|
Li G, Robinson GW, Lesche R, Martinez-Diaz H, Jiang Z, Rozengurt N, Wagner KU, Wu DC, Lane TF, Liu X, Hennighausen L, Wu H. Conditional loss of PTEN leads to precocious development and neoplasia in the mammary gland. Development 2002; 129:4159-70. [PMID: 12163417 DOI: 10.1242/dev.129.17.4159] [Citation(s) in RCA: 188] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
PTEN tumor suppressor is frequently mutated in human cancers, including breast cancers. Female patients with inherited PTEN mutations suffer from virginal hypertrophy of the breast with high risk of malignant transformation. However, the exact mechanisms of PTEN in controlling mammary gland development and tumorigenesis are unclear. In this study, we generated mice with a mammary-specific deletion of the Pten gene. Mutant mammary tissue displayed precocious lobulo-alveolar development, excessive ductal branching, delayed involution and severely reduced apoptosis. Pten null mammary epithelial cells were disregulated and hyperproliferative. Mutant females developed mammary tumors early in life. Similar phenotypes were observed in Pten-null mammary epithelia that had been transplanted into wild-type stroma, suggesting that PTEN plays an essential and cell-autonomous role in controlling the proliferation, differentiation and apoptosis of mammary epithelial cells.
Collapse
|
50
|
Miyoshi K, Rosner A, Nozawa M, Byrd C, Morgan F, Landesman-Bollag E, Xu X, Seldin DC, Schmidt EV, Taketo MM, Robinson GW, Cardiff RD, Hennighausen L. Activation of different Wnt/beta-catenin signaling components in mammary epithelium induces transdifferentiation and the formation of pilar tumors. Oncogene 2002; 21:5548-56. [PMID: 12165853 DOI: 10.1038/sj.onc.1205686] [Citation(s) in RCA: 100] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2002] [Revised: 05/13/2002] [Accepted: 05/20/2002] [Indexed: 11/08/2022]
Abstract
The Wnt/beta-catenin signaling pathway controls cell fate and neoplastic transformation. Expression of an endogenous stabilized beta-catenin (DeltaE3 beta-catenin) in mammary epithelium leads to the transdifferentiation into epidermis- and pilar-like structures. Signaling molecules in the canonical Wnt pathway upstream from beta-catenin induce glandular tumors but it is not clear whether they also cause squamous transdifferentiation. To address this question we have now investigated mammary epithelium from transgenic mice that express activating molecules of the Wnt pathway: Wnt10b, Int2/Fgf3, CK2alpha, DeltaE3 beta-catenin, Cyclin D1, and dominant negative (dn) GSK3beta. Cytokeratin 5 (CK5), which is expressed in both mammary myoepithelium and epidermis, and the epidermis-specific CK1 and CK6 were used as differentiation markers. Extensive squamous metaplasias and widespread expression of CK1 and CK6 were observed in DeltaE3 beta-catenin transgenic mammary tissue. Wnt10b and Int2 transgenes also induced squamous metaplasias, but expression of CK1 and CK6 was sporadic. While CK5 expression in Wnt10b transgenic tissue was still confined to the lining cell layer, its expression in Int2 transgenic tissue was completely disorganized. In contrast, cytokeratin expression in CK2alpha, dnGSK3beta and Cyclin D1 transgenic mammary tissues was similar to that in DeltaE3 beta-catenin tissue. In support of transdifferentiation, expression of hard keratins specific for hair and nails was observed in pilar tumors. These results demonstrate that the activation of Wnt signaling components in mammary epithelium induces not only glandular tumors but also squamous differentiation, possibly by activating LEF-1, which is expressed in normal mammary epithelium.
Collapse
|