GLUT1 and GLUT8 support lactose synthesis in Golgi of murine mammary epithelial cells

Villagrán, Marcelo; Muñoz, Mirna; Inostroza, Eveling; Venegas, Camila; Ruminot, Iván; Parra-Valencia, Esteban; Maldonado, Mauricio; Pozo, Reginald Del; Rivas, Coralia I.; Vera, Juan Carlos; Mardones, Lorena

doi:10.1007/s13105-019-00679-3

Cited by 8 publications

(17 citation statements)

References 31 publications

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“…The increase in GLUT8 expression is lower, but it follows the same pattern, associated with cytokeratin 18 and Ki67 expression and MEC proliferation [5,8]. However, some studies also found an increase of GLUT1 expression in MEC in early pregnancy, which could be related to the start of lipid synthesis in secretory activation phase, when sterol regulatory element-binding protein (SREBP), a transcription factor, appears, or to stem cell renewal [2,5,10,23]. Although the majority of authors found over 60% of GLUT1 expression in plasma membrane in rat lactating gland, some studies found it almost exclusively at intracellular level [5,19,20,24].…”

Section: Glucose Uptake In Mammary Epithelial Cellsmentioning

confidence: 73%

“…The maximum expression of GLUT1 observed was between late pregnancy and late lactation, reaching an increase of 5-fold at the protein level and 50-fold at mRNA level [5,15,17,18,22]. The increase in GLUT8 expression is lower, but it follows the same pattern, associated with cytokeratin 18 and Ki67 expression and MEC proliferation [5,8]. However, some studies also found an increase of GLUT1 expression in MEC in early pregnancy, which could be related to the start of lipid synthesis in secretory activation phase, when sterol regulatory element-binding protein (SREBP), a transcription factor, appears, or to stem cell renewal [2,5,10,23].…”

Section: Glucose Uptake In Mammary Epithelial Cellsmentioning

confidence: 93%

“…In cows, the increase in the expression of GLUTs is in order of magnitude greater than in rodents, which reflects that its secretory activity is highly dependent on the expression of glucose transporters [6,14]. The maximum expression of GLUT1 observed was between late pregnancy and late lactation, reaching an increase of 5-fold at the protein level and 50-fold at mRNA level [5,15,17,18,22]. The increase in GLUT8 expression is lower, but it follows the same pattern, associated with cytokeratin 18 and Ki67 expression and MEC proliferation [5,8].…”

Section: Glucose Uptake In Mammary Epithelial Cellsmentioning

confidence: 96%

“…In rodents, milk production is mainly associated with a high proliferation of MEC, whereas in cows it is principally due to the increase in secretory activity per cell [12]. In general, MEC proliferation is low in virgin and early pregnancy (5%) in mice, where it has been associated with stem cell renewing, but it persists throughout lactation period, associated with cell replacement, with low net growth, associated with the expression of Ki67 [5,11]. For example, in cows, the MEC replacement reaches 50%, whereas in rodents it is lower than 25% [11].…”

Section: Glucose Uptake In Mammary Epithelial Cellsmentioning

confidence: 99%

“…However, some studies also found an increase of GLUT1 expression in MEC in early pregnancy, which could be related to the start of lipid synthesis in secretory activation phase, when sterol regulatory element-binding protein (SREBP), a transcription factor, appears, or to stem cell renewal [2,5,10,23]. Although the majority of authors found over 60% of GLUT1 expression in plasma membrane in rat lactating gland, some studies found it almost exclusively at intracellular level [5,19,20,24]. Interestingly, in early weaning of BalB/BalC mice, GLUT1 is also concentrated intracellularly, but, due to a decrease in lactation at this step, that could be associated with its accumulation in proteasomal compartment or to apoptotic bodies phagocyted by other epithelial cells acting as nonprofessional phagocytes [5,25].…”

Section: Glucose Uptake In Mammary Epithelial Cellsmentioning

confidence: 99%

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Lactose Synthesis

Mardones¹,

Villagrán²

2020

Lactose and Lactose Derivatives

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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.

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Section: Glucose Uptake In Mammary Epithelial Cellsmentioning

confidence: 73%

Section: Glucose Uptake In Mammary Epithelial Cellsmentioning

confidence: 93%

Section: Glucose Uptake In Mammary Epithelial Cellsmentioning

confidence: 96%

Section: Glucose Uptake In Mammary Epithelial Cellsmentioning

confidence: 99%

Section: Glucose Uptake In Mammary Epithelial Cellsmentioning

confidence: 99%

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Lactose Synthesis

Mardones¹,

Villagrán²

2020

Lactose and Lactose Derivatives

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Structure, function and regulation of mammalian glucose transporters of the SLC2 family

Holman

2020

Pflugers Arch - Eur J Physiol

130

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The SLC2 genes code for a family of GLUT proteins that are part of the major facilitator superfamily (MFS) of membrane transporters. Crystal structures have recently revealed how the unique protein fold of these proteins enables the catalysis of transport. The proteins have 12 transmembrane spans built from a replicated trimer substructure. This enables 4 trimer substructures to move relative to each other, and thereby alternately opening and closing a cleft to either the internal or the external side of the membrane. The physiological substrate for the GLUTs is usually a hexose but substrates for GLUTs can include urate, dehydro-ascorbate and myo-inositol. The GLUT proteins have varied physiological functions that are related to their principal substrates, the cell type in which the GLUTs are expressed and the extent to which the proteins are associated with subcellular compartments. Some of the GLUT proteins translocate between subcellular compartments and this facilitates the control of their function over long-and shorttime scales. The control of GLUT function is necessary for a regulated supply of metabolites (mainly glucose) to tissues. Pathophysiological abnormalities in GLUT proteins are responsible for, or associated with, clinical problems including type 2 diabetes and cancer and a range of tissue disorders, related to tissue-specific GLUT protein profiles. The availability of GLUT crystal structures has facilitated the search for inhibitors and substrates and that are specific for each GLUT and that can be used therapeutically. Recent studies are starting to unravel the drug targetable properties of each of the GLUT proteins.

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