scholarly journals PSXII-17 Supplementing ten essential amino acids alters beta-casein expression and cell and medium protein synthesis in bovine mammary epithelial cells.

2018 ◽  
Vol 96 (suppl_3) ◽  
pp. 265-265
Author(s):  
J Conejos ◽  
J Kim ◽  
T Yadana Moe ◽  
W Choe ◽  
M Bae ◽  
...  
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Epithelial Cells ◽  
Mammary Epithelial Cells ◽  
Essential Amino Acids ◽  
Mammary Epithelial ◽  
Bovine Mammary Epithelial Cells ◽  
Beta Casein

scholarly journals Intracellular Staphylococcus aureus Infection Decreases Milk Protein Synthesis by Preventing Amino Acid Uptake in Bovine Mammary Epithelial Cells

2021 ◽  
Vol 8 ◽  
Author(s):  
Yuhao Chen ◽  
Yuze Ma ◽  
Qiang Ji ◽  
Xiaoru Yang ◽  
Xue Feng ◽  
...  
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Amino Acid ◽  
Epithelial Cells ◽  
Milk Protein ◽  
Mammary Epithelial Cells ◽  
Protein Composition ◽  
Mammary Epithelial ◽  
Bovine Mammary Epithelial Cells ◽  
Mtorc1 Signaling

Staphylococcus aureus (S. aureus) is one of the main pathogens in cow mastitis, colonizing mammary tissues and being internalized into mammary epithelial cells, causing intracellular infection in the udder. Milk that is produced by cows that suffer from mastitis due to S. aureus is associated with decreased production and changes in protein composition. However, there is limited information on how mastitis-inducing bacteria affect raw milk, particularly with regard to protein content and protein composition. The main purpose of this work was to examine how S. aureus infection affects milk protein synthesis in bovine mammary epithelial cells (BMECs). BMECs were infected with S. aureus, and milk protein and amino acid levels were determined by ELISA after S. aureus invasion. The activity of mTORC1 signaling and the transcription factors NF-κB and STAT5 and the expression of the amino acid transporters SLC1A3 and SLC7A5 were measured by western blot or immunofluorescence and RT-qPCR. S. aureus was internalized by BMECs in vitro, and the internalized bacteria underwent intracellular proliferation. Eight hours after S. aureus invasion, milk proteins were downregulated, and the level of BMECs that absorbed Glu, Asp, and Leu from the culture medium and the exogenous amino acids induced β-casein synthesis declined. Further, the activity of mTORC1 signaling, NF-κB, and STAT5 was impaired, and SLC1A3 and SLC7A5 were downregulated. Eight hours of treatment with 100 nM rapamycin inhibited NF-κB and STAT5 activity, SLC1A3 and SLC7A5 expression, and milk protein synthesis in BMECs. Thus mTORC1 regulates the expression of SLC1A3 and SLC7A5 through NF-κB and STAT5. These findings constitute a model by which S. aureus infection suppresses milk protein synthesis by decreasing amino acids uptake in BMECs.

Tenascin-C inhibits extracellular matrix-dependent gene expression in mammary epithelial cells. Localization of active regions using recombinant tenascin fragments

1995 ◽  
Vol 108 (2) ◽  
pp. 519-527 ◽  
Author(s):  
P.L. Jones ◽  
N. Boudreau ◽  
C.A. Myers ◽  
H.P. Erickson ◽  
M.J. Bissell
Keyword(s):  
Gene Expression ◽  
Extracellular Matrix ◽  
Protein Synthesis ◽  
Epithelial Cells ◽  
Mammary Epithelial Cells ◽  
Active Regions ◽  
Mammary Epithelial ◽  
Dependent Manner ◽  
Beta Casein ◽  
Casein Protein

The physiological role of tenascin in vivo has remained obscure. Although tenascin is regulated in a stage and tissue-dependent manner, knock-out mice appear normal. When tenascin expression was examined in the normal adult mouse mammary gland, little or none was present during lactation, when epithelial cells actively synthesize and secrete milk proteins in an extracellular matrix/lactogenic hormone-dependent manner. In contrast, tenascin was prominently expressed during involution, a stage characterized by the degradation of the extracellular matrix and the subsequent loss of milk production. Studies with mammary cell lines indicated that tenascin expression was high on plastic, but was suppressed in the presence of the laminin-rich, Engelbreth-Holm-Swarm (EHS) tumour biomatrix. When exogenous tenascin was added together with EHS to mammary epithelial cells, beta-casein protein synthesis and steady-state mRNA levels were inhibited in a concentration-dependent manner. Moreover, this inhibition by tenascin could be segregated from its effects on cell morphology. Using two beta-casein promoter constructs attached to the chloramphenicol acetyltransferase reporter gene we showed that tenascin selectively suppressed extracellular matrix/prolactin-dependent transcription of the beta-casein gene in three-dimensional cultures. Finally, we mapped the active regions within the fibronectin type III repeat region of the tenascin molecule that are capable of inhibiting beta-casein protein synthesis. Our data are consistent with a model where both the loss of a laminin-rich basement membrane by extracellular matrix-degrading enzymes and the induction of tenascin contribute to the loss of tissue-specific gene expression and thus the involuting process.

Lactogenic hormones regulate mammary protein synthesis in bovine mammary epithelial cells via the mTOR and JAK–STAT signal pathways

2016 ◽  
Vol 56 (11) ◽  
pp. 1803 ◽  
Author(s):  
Q. Tian ◽  
H. R. Wang ◽  
M. Z. Wang ◽  
C. Wang ◽  
S. M. Liu
Keyword(s):  
Protein Synthesis ◽  
Epithelial Cells ◽  
Milk Protein ◽  
Mammary Epithelial Cells ◽  
Signal Pathway ◽  
Mammary Epithelial ◽  
Signal Pathways ◽  
Bovine Mammary Epithelial Cells ◽  
Genes Encoding ◽  
Lactogenic Hormones

The expression of CSN3, hormone receptor, the expression of genes regulating the mTOR, JAK–STAT signal pathways, and the relative content of к-casein as well as total casein were determined in the present study to explore the mechanism of the effect of lactogenic hormones on milk-protein synthesis in bovine mammary epithelial cells. The results showed that apoptosis of the cells was increased by inhibitor LY294002, while the expressions of genes encoding PKB, Rheb, PRAS40 and S6K1 in the mTOR signal pathway, JAK2, STAT5A in the JAK–STAT signal pathway, and genes encoding INSR, PRLR, NR3C1 and CSN3 were all downregulated, and the relative contents of κ-casein and total casein were decreased in the mammary epithelial cells compared with those in the control group. Comparatively, the inhibitory effects of AG-490 were more profound than those of LY294002, and the double block using both inhibitors had a greater effect than the single block. The CSN3 gene expression was downregulated and the content of milk casein was decreased by the inhibitors. In addition, the expression of the hormone receptor genes was downregulated. Our results suggest that lactogenic hormones, via their receptors in the membrane, regulated the JAK–STAT and m-TOR signal pathways, and affected cell proliferation and apoptosis, leading to changes in milk-protein synthesis.

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