scholarly journals Identification and characterization of bovine mammary peptide transporters in response to tripeptide and lactogenic hormone treatment

2017 ◽  
Vol 62 (No. 7) ◽  
pp. 296-305 ◽  
Author(s):  
Y. Cui ◽  
X. Zhang ◽  
C. Guo ◽  
R. Du ◽  
G. Ailun ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Mammary Epithelial Cells ◽  
Bovine Milk ◽  
Hormone Treatment ◽  
Mammary Glands ◽  
Mammary Epithelial ◽  
Peptide Transporter ◽  
Western Blots ◽  
Lactogenic Hormone ◽  
Gland Function

Oligopeptide transportation is mediated by the peptide transporter (PepT), which consists of two isoforms, PepT1 and PepT2. Because PepT play essential roles in amino acid metabolism and cell growth, the aim of the present study was to identify these transporters in bovine mammary glands and to analyze the potential functions of these transporters in mammary epithelial cells. Abundance of PepT1 and PepT2 mRNA was successfully measured in both mammary glands and cultured mammary epithelial cells. In addition, the two proteins were examined using immunohistochemistry, immunocytochemistry, and Western blots. The response of mammary epithelial cells to tripeptide and lactogenic hormone treatment was assayed. The PepT mRNA abundance of cultured epithelial cells and secreted protein in the culture medium were increased after tri-peptide substitution and addition of hormones such as insulin, hydrocortisone, and prolactin. The response of mammary epithelial cells to tripeptide and hormone treatments suggests that PepT affects the mammary gland function and increases bovine milk production.

scholarly journals Dipeptide (Methionyl-Methionine) Transport and Its Effect on β-Casein Synthesis in Bovine Mammary Epithelial Cells

2018 ◽  
Vol 49 (2) ◽  
pp. 479-488 ◽  
Author(s):  
Caihong Wang ◽  
Fengqi Zhao ◽  
Jianxin Liu ◽  
Hongyun Liu
Keyword(s):  
Epithelial Cells ◽  
Cell Viability ◽  
Transport Properties ◽  
Mammary Epithelial Cells ◽  
Mammary Epithelial ◽  
Janus Kinase ◽  
Initiation Factor ◽  
Peptide Transporter ◽  
Small Interference Rna ◽  
Bovine Mammary Epithelial Cells

Background/Aims: The aim of this study was to investigate the transport properties and utilization of methionyl-methionine dipeptide (Met-Met) in β-casein (β-CN) synthesis in bovine mammary epithelial cells (BMECs). Methods: The transport properties were studied for the effects of time, pH, concentration, temperature and inhibitors using Met-Met-FITC in BMECs. BMECs were treated with different concentrations of Met-Met (0, 20, 40, 80, 120 and 160 µg/ml). In several experiments, the cells were treated with Janus kinase 2 (JAK2) inhibitor (tyrphostin AG-490, 50 µM) and mammalian target of rapamycin (mTOR) inhibitor (rapamycin, 100 ng/ml). Results: The uptake of Met-Met-FITC by BMECs was rapid during the first fifteen minutes and became saturated after 15 minutes. The transport of Met-Met-FITC in BMECs exhibited a Michaelis constant of 52.4 µM and maximum transport velocity of 14.8 pmol/min/mg protein. The uptake of Met-Met-FITC in BMECs was pH-dependent, peaked at pH 6.5 and was significantly inhibited by other peptides, including Met-Lys, Lys-Lys, Gly-Met, Gly-Leu and Met-Leu. Knocking down the peptide transporter 2 (PepT2) with small interference RNA markedly decreased Met-Met-FITC uptake. Met-Met concentration-dependently increased the PepT2 expression and β-CN synthesis in BMECs with an optimal concentration of 80 µg/ml. At 80 µg/ml, Met-Met also enhanced the cell viability and cyclin D1 expression and promoted cell cycle transition from G1 phase to S phase. In addition, 80 µg/ml Met-Met increased the mRNA abundance of JAK2 and signal transducer and activator of transcription 5 (STAT5) and enhanced the phosphorylation of JAK2, STAT5, mTOR, p70 ribosomal S6 kinase 1 and eukaryotic initiation factor 4E binding protein 1. The inhibition of JAK2 and mTOR significantly decreased Met-Met-induced increase in cell viability and β-CN synthesis in BMECs. Conclusion: Our data elucidated the properties of peptide transporter and its effect on β-CN synthesis in BMECs. Met-Met, taken up by PepT2, enhances cell proliferation and promotes β-CN synthesis by activating JAK2-STAT5 and mTOR signaling pathways in BMECs.

scholarly journals beta-Casein mRNA sequesters a single-stranded nucleic acid-binding protein which negatively regulates the beta-casein gene promoter.

1994 ◽  
Vol 14 (9) ◽  
pp. 6004-6012 ◽  
Author(s):  
S Altiok ◽  
B Groner
Keyword(s):  
Epithelial Cells ◽  
Untranslated Region ◽  
Mammary Epithelial Cells ◽  
Gene Promoter ◽  
Regulatory Elements ◽  
Hormonal Control ◽  
Mammary Epithelial ◽  
Casein Gene ◽  
Lactogenic Hormone ◽  
Beta Casein

beta-Casein gene expression in mammary epithelial cells is under the control of the lactogenic hormones, glucocorticoids, insulin, and prolactin. The hormonal control affects gene transcription, and several regulatory elements in the beta-casein gene promoter between positions -80 and -221 have previously been identified. A region located in the promoter between positions -170 and -221 contains overlapping sequences for negative and positive regulatory elements. A sequence-specific single-stranded DNA-binding factor (STR), composed of two proteins with molecular masses of 35 and 54 kDa, recognizes the upper strand of this region and has a repressing role in transcription. High-level STR binding activity was observed in nuclear extracts from mammary glands of pregnant and postlactating mice and from noninduced HC11 mammary epithelial cells, cells with a low level of transcriptional activity of the beta-casein gene. STR activity is downregulated in mammary epithelial cells during lactation of the animals and after lactogenic hormone induction of HC11 cells in culture. These cells strongly transcribe the beta-casein gene. We investigated the mechanism of downregulation and found that a lactogenic-hormone-induced molecule (I-STR) inhibits STR from binding to its DNA target. I-STR is composed of RNA. STR is sequestered into the cytoplasm by I-STR after lactogenic hormone induction of mammary epithelial cells and remains present in an RNA-bound form. A high-affinity STR binding site was found in the 5' untranslated region of beta-casein mRNA. We propose that beta-casein mRNA can function as I-STR. beta-Casein mRNA may positively regulate its own transcription by translocating STR from the nucleus to the cytoplasm. The beta-casein STR binding sequence increases expression of a transfected beta-galactosidase gene when it is placed into the 5' untranslated region sequence of the mRNA. STR may have a positive role in posttranscriptional regulation.

scholarly journals Signal Transducer and Activator of Transcription 5a Mediates Mammary Ductal Branching and Proliferation in the Nulliparous Mouse

Endocrinology ◽  
2010 ◽  
Vol 151 (6) ◽  
pp. 2876-2885 ◽  
Author(s):  
Sarah J. Santos ◽  
Sandra Z. Haslam ◽  
Susan E. Conrad
Keyword(s):  
Mammary Gland ◽  
Epithelial Cells ◽  
Mammary Gland Development ◽  
Kinase Inhibitor ◽  
Mammary Epithelial Cells ◽  
Nuclear Factor Κb ◽  
Mammary Glands ◽  
Mammary Epithelial ◽  
Signal Transducer ◽  
Gland Development

Signal transducer and activator of transcription (Stat)5a is a critical regulator of mammary gland development. Previous studies have focused on Stat5a’s role in the late pregnant and lactating gland, and although active Stat5a is detectable in mammary epithelial cells in virgin mice, little is known about its role during early mammary gland development. In this report, we compare mammary gland morphology in pubertal and adult nulliparous wild-type and Stat5a−/− mice. The Stat5a-null mammary glands exhibited defects in secondary and side branching, providing evidence that Stat5a regulates these processes. In addition, Stat5a−/− mammary glands displayed an attenuated proliferative response to pregnancy levels of estrogen plus progesterone (E+P), suggesting that it plays an important role in early pregnancy. Finally, we examined one potential mediator of Stat5a’s effects, receptor activator of nuclear factor-κB ligand (RANKL). Stat5a−/− mammary glands were defective in inducing RANKL in response to E+P treatment. In addition, regulation of several reported RANKL targets, including inhibitor of DNA binding 2 (Id2), cyclin D1, and the cyclin-dependent kinase inhibitor p21Waf1/Cip1, was altered in Stat5a−/− mammary cells, suggesting that one or more of these proteins mediate the effects of Stat5a in E+P-treated mammary epithelial cells.

scholarly journals Productive Infection of Mouse Mammary Glands and Human Mammary Epithelial Cells by Zika Virus

Viruses ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 950 ◽  
Author(s):  
Hubert ◽  
Chiche ◽  
Legros ◽  
Jeannin ◽  
Montange ◽  
...  
Keyword(s):  
Breast Milk ◽  
Epithelial Cells ◽  
Zika Virus ◽  
Mammary Epithelial Cells ◽  
Mammary Glands ◽  
Mammary Epithelial ◽  
Human Breast Milk ◽  
Human Breast ◽  
Human Mammary Epithelial Cells ◽  
Human Mammary Epithelial

Zika virus (ZIKV) belongs to the large category of arboviruses. Surprisingly, several human-to-human transmissions of ZIKV have been notified, either following sexual intercourse or from the mother to fetus during pregnancy. Importantly, high viral loads have been detected in the human breast milk of infected mothers, and the existence of breastfeeding as a new mode of mother-to-child transmission of ZIKV was recently hypothesized. However, the maternal origin of infectious particles in breast milk is currently unknown. Here, we show that ZIKV disseminates to the mammary glands of infected mice after both systemic and local exposure with differential kinetics. Ex vivo, we demonstrate that primary human mammary epithelial cells were sensitive and permissive to ZIKV infection in this study. Moreover, by using in vitro models, we prove that mammary luminal- and myoepithelial-phenotype cell lines are both able to produce important virus progeny after ZIKV exposure. Our data suggest that the dissemination of ZIKV to the mammary glands and subsequent infection of the mammary epithelium could be one mechanism of viral excretion in human breast milk.

scholarly journals GosB Inhibits Triacylglycerol Synthesis and Promotes Cell Survival in Mouse Mammary Epithelial Cells

2017 ◽  
Vol 2017 ◽  
pp. 1-12
Author(s):  
Gaoxiao Xu ◽  
Saixing Duan ◽  
Jianye Hou ◽  
Zhongxin Wei ◽  
Guangwei Zhao
Keyword(s):  
Fatty Acid ◽  
Epithelial Cells ◽  
Milk Fat ◽  
Fatty Acid Synthase ◽  
Mammary Epithelial Cells ◽  
Mammary Glands ◽  
Mammary Epithelial ◽  
Milk Fatty Acid ◽  
Fatty Acid Binding ◽  
Triacylglycerol Synthesis

It has been demonstrated that the activator protein related transcription factor Finkel-Biskis-Jinkins murine osteosarcoma B (GosB) is involved in preadipocyte differentiation and triacylglycerol synthesis. However, the role of GosB in regulating the synthesis of milk fatty acid in mouse mammary glands remains unclear. This research uncovered potentially new roles of GosB in suppressing milk fatty acid synthesis. Results revealed that GosB had the highest expression in lung tissue and showed a higher expression level during nonlactation than during lactation. GosB inhibited the expression of fatty acid synthase (FASN), stearoyl-CoA desaturase (SCD), fatty acid binding protein 4 (FABP4), diacylglycerol acyltransferase 1 (DGAT1), perilipin 2 (PLIN2), perilipin 3 (PLIN3), and C/EBPα in mouse mammary gland epithelial cells (MEC). In addition, GosB reduced cellular triglyceride content and the accumulation of lipid droplets; in particular, GosB enhanced saturated fatty acid concentration (C16:0 and C18:0). The PPARγ agonist, rosiglitazone (ROSI), promoted apoptosis and inhibited cell proliferation. GosB increased the expression of Bcl-2 and protected MEC from ROSI-induced apoptosis. Furthermore, MECs were protected from apoptosis through the GosB regulation of intracellular calcium concentrations. These findings suggest that GosB may regulate mammary epithelial cells milk fat synthesis and apoptosis via PPARγ in mouse mammary glands.

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.

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