scholarly journals Lactose Synthesis

2020 ◽  
Author(s):  
Lorena Mardones ◽  
Marcelo Villagrán
Keyword(s):  
Glucose Transporter ◽  
Mammary Epithelial Cells ◽  
Mammalian Species ◽  
Glucose Transporters ◽  
Mammary Epithelial ◽  
Enzyme Complex ◽  
Mammal Species ◽  
Lactose Synthase ◽  
Lactose Synthesis ◽  
Osmotic Properties

This chapter is related to lactose synthesis, its chemistry, regulation, and differences between species, especially in cattle. Lactose synthesis takes place in the Golgi apparatus of mammary epithelial cells (MEC) by the lactose synthase (LS) enzyme complex from two precursors, glucose and UDP-galactose. The enzyme complex is formed by galactosyltransferase, and it is associated with α-lactalbumin. Importantly, the lactose secreted determines the volume of milk produced, due to its osmotic properties. Milk contains 5% lactose and 80% water, percentages that remain constant during lactation in the different mammalian species. The low variation in milk lactose content indicates that lactose synthesis remains constant throughout the period of lactation and that is highly conserved in all mammals. Lactose synthesis is initiated during the first third of the pregnancy, increasing after birth and placenta removal. Different glucose transporters have been involved in mammary glucose uptake, mainly facilitative glucose transporters GLUT1, GLUT8, and GLUT12 and sodium-glucose transporter SGLT1, with more or less participation depending on mammal species.

Peroxisome proliferator-activated receptor β/δ does not regulate glucose uptake and lactose synthesis in bovine mammary epithelial cells cultivated in vitro

2018 ◽  
Vol 85 (3) ◽  
pp. 295-302 ◽  
Author(s):  
Jayant Lohakare ◽  
Johan S Osorio ◽  
Massimo Bionaz
Keyword(s):  
Epithelial Cells ◽  
Glucose Uptake ◽  
Glucose Transporter ◽  
Mammary Epithelial Cells ◽  
Significant Inhibition ◽  
Mammary Epithelial ◽  
Pyruvate Dehydrogenase Kinase ◽  
Bovine Mammary Epithelial Cells ◽  
Gene Reporter Assay ◽  
Lactose Synthesis

The hypothesis of the study was that inhibition of PPARβ/δ increases glucose uptake and lactose synthesis in bovine mammary epithelial cells by reducing the expression of the glucose transporter mRNA destabiliser calreticulin. Three experiments were conducted to test the hypothesis using immortalised bovine mammary alveolar (MACT) and primary bovine mammary (PBMC) cells. In Experiment 1, the most effective dose to inhibit PPARβ/δ activity among two synthetic antagonists (GSK-3787 and PT-s58) was assessed using a gene reporter assay. In Experiment 2, the effect on glucose uptake and lactose synthesis was evaluated by measuring glucose and lactose in the media and expression of related key genes upon modulation of PPARβ/δ using GSK-3787, the synthetic PPARβ/δ agonist GW-501516, or a combination of the two in cells cultivated in plastic. In Experiment 3, the same treatments were applied to cells cultivated in Matrigel and glucose and lactose in media were measured. In Experiment 1 it was determined that a significant inhibition of PPARβ/δ in the presence or absence of fetal bovine serum was achieved with ≥ 1000 nm GSK-3787 but no significant inhibition was observed with PT-s58. In Experiment 2, inhibition of PPARβ/δ had no effect on glucose uptake and lactose synthesis but they were both increased by GW-501516 in PBMC. The mRNA abundance of PPARβ/δ target gene pyruvate dehydrogenase kinase 4 was increased but transcription of calreticulin was decreased (only in MACT cells) by GW-501516. Treatment with GSK-3787 did not affect the transcription of measured genes. No effects on glucose uptake or lactose synthesis were detected by modulation of PPARβ/δ activity on cells cultivated in Matrigel. The above data do not provide support for the original hypothesis and suggest that PPARβ/δ does not play a major role in glucose uptake and lactose synthesis in bovine mammary epithelial cells.

scholarly journals Effects of glucose on lactose synthesis in mammary epithelial cells from dairy cow

2016 ◽  
Vol 12 (1) ◽  
Author(s):  
Ye Lin ◽  
Xiaoxu Sun ◽  
Xiaoming Hou ◽  
Bo Qu ◽  
Xuejun Gao ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Dairy Cow ◽  
Mammary Epithelial Cells ◽  
Mammary Epithelial ◽  
Lactose Synthesis

Expression Profiling of Glucose Transporter 1 (GLUT1) and Apoptotic Genes (BAX and BCL2) in Milk Enriched Mammary Epithelial Cells (MEC) in Riverine Buffalo during Lactation

2014 ◽  
Vol 25 (3) ◽  
pp. 151-159 ◽  
Author(s):  
Poonam Yadav ◽  
Desh Deepak Singh ◽  
Manishi Mukesh ◽  
R. S. Kataria ◽  
Anita Yadav ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Expression Profiling ◽  
Glucose Transporter ◽  
Mammary Epithelial Cells ◽  
Mammary Epithelial ◽  
Glucose Transporter 1 ◽  
Apoptotic Genes

Pro-inflammatory cytokine TNF-α is a key inhibitory factor for lactose synthesis pathway in lactating mammary epithelial cells

2016 ◽  
Vol 340 (2) ◽  
pp. 295-304 ◽  
Author(s):  
Ken Kobayashi ◽  
Chinatsu Kuki ◽  
Shoko Oyama ◽  
Haruto Kumura
Keyword(s):  
Epithelial Cells ◽  
Inflammatory Cytokine ◽  
Mammary Epithelial Cells ◽  
Mammary Epithelial ◽  
Inhibitory Factor ◽  
Tnf Α ◽  
Lactose Synthesis

Glucose transporter in bovine mammary epithelial cells is an asymmetric carrier that exhibits cooperativity and trans-stimulation

2003 ◽  
Vol 285 (5) ◽  
pp. C1226-C1234 ◽  
Author(s):  
Changting Xiao ◽  
John P. Cant
Keyword(s):  
Epithelial Cells ◽  
Glucose Transporter ◽  
Mammary Epithelial Cells ◽  
Mammary Epithelial ◽  
Isolated Cells ◽  
Experimental Conditions ◽  
Bovine Mammary Epithelial Cells ◽  
Equilibrium Exchange ◽  
Uptake Activity

Glucose transport kinetics were quantified in isolated bovine mammary epithelial cells using 3- O-methyl-d-glucose. Isolated cells retained satisfactory viability and glucose uptake activity, which was inhibited by cytochalasin B, phloretin, HgCl2, and low temperature. Initial rates of entry were measured over a 15-s interval at 37°C under zero- trans, equilibrium-exchange, high- cis, and high- trans concentrations of 3- O-methyl-d-glucose between 0 and 20 mM. The combined set of rate measurements from all experimental conditions was fit to the fixed-site carrier model by nonlinear regression to estimate parameters of transport. For the regression between predicted and observed initial rates, r2 was 0.97. Forward Vmax was estimated at 18.2 nmol·min-1·mg protein-1, and the Michaelis constant was 8.29 mM. The cooperativity parameter was 1.63, trans-stimulation was 2.13-fold, and asymmetry was 2.06-fold. On the basis of the kinetic parameters, variations in intracellular glucose concentrations are not responsible for the range of glucose uptakes by bovine mammary glands observed in vivo.

Expression and localisation of glucose transporter 1 (GLUT1) in dairy goat mammary gland at different physiological stages

2009 ◽  
Vol 89 (4) ◽  
pp. 475-480 ◽  
Author(s):  
Z Na ◽  
L Qingzhang ◽  
G Xuejun ◽  
N Xuemei ◽  
Y Hongbo ◽  
...  
Keyword(s):  
Mammary Gland ◽  
Epithelial Cells ◽  
Glucose Transporter ◽  
Mammary Epithelial Cells ◽  
Mammary Epithelial ◽  
Dairy Goat ◽  
Apical Plasma Membrane ◽  
Glucose Transporter 1 ◽  
Glut1 Protein ◽  
Glut1 Mrna

Glucose is the major energy source for mammary epithelial cells, as well as an important substrate for lactose synthesis. Mammary epithelial cells take up glucose from extracellular fluid into the cell through glucose transporter (GLUT). This study was aimed at investigating the expression of GLUT1 glucose transporter in dairy goat mammary gland during puberty, pregnancy, lactation, and involution. Using real-time reverse transcription PCR (qRT-PCR) and Western blotting, we analyzed the expression of GLUT1 mRNA and protein in dairy goat mammary gland. GLUT1 mRNA and protein expression increased during pregnancy and lactation, especially at peak lactation, and decreased strongly after weaning. Furthermore, the location of GLUT1 protein was determined by immunofluorescence laser confocal microscopy. GLUT1 protein localised to the basal and apical plasma membrane of epithelial cells, and also in the cytoplasm. The results from this study showed that GLUT1 is expressed in the dairy goat mammary gland with the greatest expression found in mammary epithelial cells during pregnancy and lactation.Key words: Expression, glucose transporter, goat, mammary gland

scholarly journals Interrelationship of glycogen metabolism and lactose synthesis in mammary epithelial cells of mice

1980 ◽  
Vol 192 (2) ◽  
pp. 695-702 ◽  
Author(s):  
J T Emerman ◽  
J C Bartley ◽  
M J Bissell
Keyword(s):  
Epithelial Cells ◽  
Mammary Epithelial Cells ◽  
Glycogen Synthase ◽  
Glycogen Synthesis ◽  
Late Pregnancy ◽  
Glycogen Metabolism ◽  
Mouse Mammary Gland ◽  
Mammary Epithelial ◽  
Glycogen Accumulation ◽  
Lactose Synthesis

Glycogen metabolism in mammary epithelial cells was investigated (i) by studying the conversion of glucose into glycogen and other cellular products in these cells from virgin, pregnant and lactating mice and (ii) by assaying the enzymes directly involved with glycogen metabolism. We find that: (1) mammary epithelial cells synthesized glycogen at rates up to over 60% that of the whole gland; (2) the rate of this synthesis was modulated greatly during the reproductive cycle, reaching a peak in late pregnancy and decreasing rapidly at parturition, when abundant synthesis of lactose was initiated; (3) glycogen synthase and phosphorylase activities reflected this modulation in glycogen metabolism; (4) lactose synthesis reached a plateau during late pregnancy, even though lactose synthase is reported to increase in the mouse mammary gland at this time. We propose that glycogen synthesis restricts lactose synthesis during late pregnancy by competing successfully for the shared UDP-glucose pool. The physiological advantage of glycogen accumulation during late pregnancy is discussed.

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