Correction: Pleiotrophin (PTN) Expression and Function and in the Mouse Mammary Gland and Mammary Epithelial Cells

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.

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Signal Transducer and Activator of Transcription 3 Activates CCAAT Enhancer-binding Protein δ Gene Transcription in G0Growth-arrested Mouse Mammary Epithelial Cells and in Involuting Mouse Mammary Gland

Journal of Biological Chemistry ◽

10.1074/jbc.m004476200 ◽

2000 ◽

Vol 275 (37) ◽

pp. 29123-29131 ◽

Cited By ~ 49

Author(s):

Julie A. Hutt ◽

John P. O'Rourke ◽

Jim DeWille

Keyword(s):

Mammary Gland ◽

Epithelial Cells ◽

Gene Transcription ◽

Mammary Epithelial Cells ◽

Binding Protein ◽

Mouse Mammary Gland ◽

Mammary Epithelial ◽

Signal Transducer ◽

Enhancer Binding Protein ◽

Transcription 3

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The Type 7 Serotonin Receptor, 5-HT7, Is Essential in the Mammary Gland for Regulation of Mammary Epithelial Structure and Function

BioMed Research International ◽

10.1155/2015/364746 ◽

2015 ◽

Vol 2015 ◽

pp. 1-8 ◽

Cited By ~ 6

Author(s):

Vaibhav P. Pai ◽

Laura L. Hernandez ◽

Malinda A. Stull ◽

Nelson D. Horseman

Keyword(s):

Mammary Gland ◽

Epithelial Cells ◽

Serotonin Receptor ◽

Mammary Epithelial Cells ◽

Mammary Epithelium ◽

Mammary Epithelial ◽

Lactation Performance ◽

Epithelial Structure ◽

And Function ◽

First Time

Autocrine-paracrine activity of serotonin (5-hydroxytryptamine, 5-HT) is a crucial homeostatic parameter in mammary gland development during lactation and involution. Published studies suggested that the 5-HT7receptor type was important for mediating several effects of 5-HT in the mammary epithelium. Here, using 5-HT7receptor-null (HT7KO) mice we attempt to understand the role of this receptor in mediating 5-HT actions within the mammary gland. We demonstrate for the first time that HT7KO dams are inefficient at sustaining their pups. Histologically, the HT7KO mammary epithelium shows a significant deviation from the normal secretory epithelium in morphological architecture, reduced secretory vesicles, and numerous multinucleated epithelial cells with atypically displaced nuclei, during lactation. Mammary epithelial cells in HT7KO dams also display an inability to transition from lactation to involution as normally seen by transition from a columnar to a squamous cell configuration, along with alveolar cell apoptosis and cell shedding. Our results show that 5-HT7is required for multiple actions of 5-HT in the mammary glands including core functions that contribute to changes in cell shape and cell turnover, as well as specialized secretory functions. Understanding these actions may provide new interventions to improve lactation performance and treat diseases such as mastitis and breast cancer.

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Targeted Expression of GLI1 in the Mammary Gland Disrupts Pregnancy-induced Maturation and Causes Lactation Failure

Journal of Biological Chemistry ◽

10.1074/jbc.m704280200 ◽

2007 ◽

Vol 282 (49) ◽

pp. 36090-36101 ◽

Cited By ~ 31

Author(s):

Marie Fiaschi ◽

Björn Rozell ◽

Åsa Bergström ◽

Rune Toftgård ◽

Marika I. Kleman

Keyword(s):

Mammary Gland ◽

Epithelial Cells ◽

Signaling Pathway ◽

Hedgehog Signaling ◽

Mammary Epithelial Cells ◽

Mammary Epithelial ◽

Hedgehog Signaling Pathway ◽

Milk Protein Gene ◽

Milk Protein Gene Expression ◽

And Function

The Hedgehog signaling pathway regulates the development and function of numerous tissues and when mis-regulated causes tumorigenesis. To assess the role of a deregulated Hedgehog signaling pathway in the mammary gland we targeted the expression of the Hedgehog effector protein, GLI1, to mammary epithelial cells using a bigenic inducible system. A constitutively active Hedgehog signaling pathway resulted with 100% penetrance in an undifferentiated mammary lobuloalveolar network during pregnancy. GLI1-expressing transgenic females were unable to lactate and milk protein gene expression was essentially absent. The inability to lactate was permanent and independent of continued GLI1 transgene expression. An increased expression of the GLI1 response gene Snail coupled to reduced expression of E-cadherin and STAT5 in the transgenic mammary gland provides a likely molecular explanation, underlying the observed phenotypic changes. In addition, remodeling of the mammary gland after parturition was impaired and expression of GLI1 was associated with accumulation of cellular debris in the mammary ducts during involution, indicating a defect in the clearance of dead cells. Areas with highly proliferative epithelial cells were observed in mammary glands with induced expression of GLI1. Within such areas an increased frequency of cells expressing nuclear Cyclin D1 was observed. Taken together the data support the notion that correct regulation of Hedgehog signaling within the epithelial cell compartment is critical for pregnancy-induced mammary gland development and remodeling.

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