Developmental changes in glucose transport, lipid composition, and fluidity of jejunal BBM

1997 ◽  
Vol 273 (3) ◽  
pp. R1086-R1093 ◽  
Author(s):  
C. M. Vazquez ◽  
N. Rovira ◽  
V. Ruiz-Gutierrez ◽  
J. M. Planas
Keyword(s):  
Glucose Uptake ◽  
Glucose Transport ◽  
Lipid Composition ◽  
Brush Border Membrane ◽  
Glucose Transporter ◽  
Specific Binding ◽  
Molar Ratio ◽  
Site Density ◽  
Age Related ◽  
Age Dependent

Na(+)-dependent D-glucose uptake was studied in jejunal brush-border membrane (BBM) vesicles of chickens at 2 days and 1, 2, 5-6, and 12-14 wk of age. Both initial rates and accumulation ratios of the Na(+)-dependent D-glucose transport were significantly higher during the 1st wk than at other ages. To explain the age-related changes observed in the transport of D-glucose, the phlorizin-specific binding, Na+ permeability, lipid composition, and fluidity were studied. Transporter site density was quantified using 50 mumol/l phlorizin and found to be higher during the 1st wk. During the 2nd wk it decreased and then remained constant. Permeability of Na+, studied using 22Na+, showed that fluxes were similar during the first 6 wk, and a significant decrease was observed in the oldest group. Furthermore, membrane fluidity results showed a significant age-dependent decrease that correlated well with both the increased molar ratio of cholesterol to phospholipid and the decreased ratio of lipid to protein found during development. In conclusion, changes in the density of Na(+)-dependent D-glucose transporter as well as in lipid content and fluidity might be involved in the changes observed in D-glucose uptake during the posthatching development.

Diabetes mellitus and expression of the enterocyte renin-angiotensin system: implications for control of glucose transport across the brush border membrane

2009 ◽  
Vol 297 (3) ◽  
pp. C601-C610 ◽  
Author(s):  
Tung Po Wong ◽  
Edward S. Debnam ◽  
Po Sing Leung
Keyword(s):  
Diabetes Mellitus ◽  
Glucose Uptake ◽  
Glucose Transport ◽  
Brush Border ◽  
Inhibitory Action ◽  
Brush Border Membrane ◽  
Glucose Transporter ◽  
Renin Angiotensin System ◽  
Angiotensin System

Streptozotocin-induced (Type 1) diabetes mellitus (T1DM) in rats promotes jejunal glucose transport, but the trigger for this response remains unclear. Our recent work using euglycemic rats has implicated the enterocyte renin-angiotensin system (RAS) in control of sodium-dependent glucose transporter (SGLT1)-mediated glucose uptake across the jejunal brush border membrane (BBM). The aim of the present study was to examine whether expression of enterocyte RAS components is influenced by T1DM. The effects of mucosal addition of angiotensin II (AII) on [14C]-d-glucose uptake by everted diabetic jejunum was also determined. Two-week diabetes caused a fivefold increase in blood glucose level and reduced mRNA and protein expression of AII type 1 (AT1) and AT2 receptors and angiotensin-converting enzyme in isolated jejunal enterocytes. Angiotensinogen expression was, however, stimulated by diabetes while renin was not detected in either control or diabetic enterocytes. Diabetes stimulated glucose uptake into everted jejunum by 58% and increased the BBM expression of SGLT1 and facilitated glucose transporter 2 (GLUT2) proteins, determined by Western blotting by 25% and 135%, respectively. Immunohistochemistry confirmed an enhanced BBM expression of GLUT2 in diabetes and also showed that this was due to translocation of the transporter from the basolateral membrane to BBM. AII (5 μM) or L-162313 (1 μM), a nonpeptide AII analog, decreased glucose uptake by 18% and 24%, respectively, in diabetic jejunum. This inhibitory action was fully accountable by an action on SGLT1-mediated transport and was abolished by the AT1 receptor antagonist losartan (1 μM). The decreased inhibitory action of AII on in vitro jejunal glucose uptake in diabetes compared with that noted previously in jejunum from normal animals is likely to be due to reduced RAS expression in diabetic enterocytes, together with a disproportionate increase in GLUT2, compared with SGLT1 expression at the BBM.

Effects of epinephrine on insulin-stimulated glucose uptake and GLUT-4 phosphorylation in muscle

1997 ◽  
Vol 273 (3) ◽  
pp. C1082-C1087 ◽  
Author(s):  
A. D. Lee ◽  
P. A. Hansen ◽  
J. Schluter ◽  
E. A. Gulve ◽  
J. Gao ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Glucose Uptake ◽  
Glucose Transport ◽  
Glucose Transporter ◽  
Inhibitory Effect ◽  
Phosphate Concentration ◽  
Intrinsic Activity ◽  
Adrenergic Stimulation ◽  
Beta Adrenergic ◽  
Glut 4

beta-Adrenergic stimulation has been reported to inhibit insulin-stimulated glucose transport in adipocytes. This effect has been attributed to a decrease in the intrinsic activity of the GLUT-4 isoform of the glucose transporter that is mediated by phosphorylation of GLUT-4. Early studies showed no inhibition of insulin-stimulated glucose transport by epinephrine in skeletal muscle. The purpose of this study was to determine the effect of epinephrine on GLUT-4 phosphorylation, and reevaluate the effect of beta-adrenergic stimulation on insulin-activated glucose transport, in skeletal muscle. We found that 1 microM epinephrine, which raised adenosine 3',5'-cyclic monophosphate approximately ninefold, resulted in GLUT-4 phosphorylation in rat skeletal muscle but had no inhibitory effect on insulin-stimulated 3-O-methyl-D-glucose (3-MG) transport. In contrast to 3-MG transport, the uptakes of 2-deoxyglucose and glucose were markedly inhibited by epinephrine treatment. This inhibitory effect was presumably mediated by stimulation of glycogenolysis, which resulted in an increase in glucose 6-phosphate concentration to levels known to severely inhibit hexokinase. We conclude that 1) beta-adrenergic stimulation decreases glucose uptake by raising glucose 6-phosphate concentration, thus inhibiting hexokinase, but does not inhibit insulin-stimulated glucose transport and 2) phosphorylation of GLUT-4 has no effect on glucose transport in skeletal muscle.

Na+-independent D-glucose transport in rabbit renal basolateral membranes

1988 ◽  
Vol 254 (5) ◽  
pp. F711-F718 ◽  
Author(s):  
P. T. Cheung ◽  
M. R. Hammerman
Keyword(s):  
Glucose Uptake ◽  
Glucose Transport ◽  
Brush Border ◽  
Glucose Transporter ◽  
Cytochalasin B ◽  
Basolateral Membrane ◽  
Membrane Vesicles ◽  
Rabbit Kidney ◽  
Basolateral Membrane Vesicles ◽  
Proximal Tubular

To define the mechanism by which glucose is transported across the basolateral membrane of the renal proximal tubular cell, we measured D-[14C]glucose uptake in basolateral membrane vesicles from rabbit kidney. Na+-dependent D-glucose transport, demonstrable in brush-border vesicles, could not be demonstrated in basolateral membrane vesicles. In the absence of Na+, the uptake of D-[14C]glucose in basolateral vesicles was more rapid than that of L-[3H]glucose over a concentration range of 1-50 mM. Subtraction of the latter from the former uptakes revealed a saturable process with apparent Km of 9.9 mM and Vmax of 0.80 nmol.mg protein-1.s-1. To characterize the transport component of D-glucose uptake in basolateral vesicles, we measured trans stimulation of 2 mM D-[14C]glucose entry in the absence of Na+. Trans stimulation could be effected by preloading basolateral vesicles with D-glucose, 2-deoxy-D-glucose, or 3-O-methyl-D-glucose, but not with L-glucose or alpha-methyl-D-glucoside. Trans-stimulated D-[14C]glucose uptake was inhibited by 0.1 mM phloretin or cytochalasin B but not phlorizin. In contrast, Na+-dependent D-[14C]glucose transport in brush-border vesicles was inhibited by phlorizin but not phloretin or cytochalasin B. Our findings are consistent with the presence of a Na+-independent D-glucose transporter in the proximal tubular basolateral membrane with characteristics similar to those of transporters present in nonepithelial cells.

Functional Expression of Sodium-Dependent Glucose Transporter in Amelogenesis

2020 ◽  
Vol 99 (8) ◽  
pp. 977-986
Author(s):  
H. Ida-Yonemochi ◽  
K. Otsu ◽  
H. Harada ◽  
H. Ohshima
Keyword(s):  
Organ Culture ◽  
Glucose Uptake ◽  
Glucose Transport ◽  
Glucose Transporter ◽  
Glucose Transporters ◽  
Maturation Stage ◽  
Sodium Dependent ◽  
Tooth Morphogenesis

Glucose is an essential source of energy for mammalian cells and is transported into the cells by glucose transporters. There are 2 types of glucose transporters: one is a passive glucose transporter, GLUT ( SLC2A), and the other is a sodium-dependent active glucose transporter, SGLT ( SLC5A). We previously reported that the expression of GLUTs during tooth development is precisely and spatiotemporally controlled and that the glucose uptake mediated by GLUT1 plays a crucial role in early tooth morphogenesis and tooth size determination. This study aimed to clarify the localization and roles of SGLT1 and SGLT2 in murine ameloblast differentiation by using immunohistochemistry, immunoelectron microscopy, an in vitro tooth organ culture experiment, and in vivo administration of an inhibitor of SGLT1/2, phloridzin. SGLT1, which has high affinity with glucose, was immunolocalized in the early secretory ameloblasts and the ruffle-ended ameloblasts in the maturation stage. However, SGLT2, which has high glucose transport capacity, was observed in the stratum intermedium, papillary layer, and ameloblasts at the maturation stage and colocalized with Na+-K+-ATPase. The inhibition of SGLT1/2 by phloridzin in the tooth germs induced the disturbance of ameloblast differentiation and enamel matrix formation both in vitro (organ culture) and in vivo (mouse model). The expression of SGLT1 and SGLT2 was significantly upregulated in hypoxic conditions in the ameloblast-lineage cells. These findings suggest that the active glucose uptake mediated by SGLT1 and SGLT2 is strictly regulated and dependent on the intra- and extracellular microenvironments during tooth morphogenesis and that the appropriate passive and active glucose transport is an essential event in amelogenesis.

Effect of diet on insulin- and contraction-mediated glucose transport and uptake in rat muscle

1995 ◽  
Vol 269 (3) ◽  
pp. R544-R551 ◽  
Author(s):  
X. Han ◽  
T. Ploug ◽  
H. Galbo
Keyword(s):  
Glucose Uptake ◽  
Glucose Transport ◽  
Glucose Transporter ◽  
Fiber Types ◽  
Transport Capacity ◽  
Glut 1 ◽  
Glut 4 ◽  
Red Muscle ◽  
Muscle Glucose Transport ◽  
Stimulation Of

A diet rich in fat diminishes insulin-mediated glucose uptake in muscle. This study explored whether contraction-mediated glucose uptake is also affected. Rats were fed a diet rich in fat (FAT, 73% of energy) or carbohydrate (CHO, 66%) for 5 wk. Hindquarters were perfused, and either glucose uptake or glucose transport capacity (uptake of 3-O-[14C]-methyl-D-glucose (40 mM)) was measured. Amounts of glucose transporter isoform GLUT-1 and GLUT-4 glucose-transporting proteins were determined by Western blot. Glucose uptake was lower (P < 0.05) in hindlegs from FAT than from CHO rats at submaximum and maximum insulin [4 +/- 0.4 vs. 5 +/- 0.3 (SE) mumol.min-1.leg-1 at 150 microU/ml insulin] as well as during prolonged stimulation of the sciatic nerve (4.4 +/- 0.4 vs. 5.6 +/- 0.6 mumol.min-1.leg-1). Maximum glucose transport elicited by insulin (soleus: 1.7 +/- 0.2 vs. 2.6 +/- 0.2 mumol.g-1.5 min-1, P < 0.05) or contractions (soleus: 1.8 +/- 0.2 vs. 2.6 +/- 0.3, P < 0.05) in red muscle was decreased in parallel in FAT compared with CHO rats. GLUT-4 content was decreased by 13-29% (P < 0.05) in the various fiber types, whereas GLUT-1 content was identical in FAT compared with CHO rats. It is concluded that a FAT diet reduces both insulin and contraction stimulation of glucose uptake in muscle and that these effects are associated with diminished skeletal muscle glucose transport capacities and GLUT-4 contents.

scholarly journals Age-Dependent Regulation of Lipogenesis in Human and Rat Adipocytes

2004 ◽  
Vol 89 (9) ◽  
pp. 4601-4606 ◽  
Author(s):  
Ashraf F. Kamel ◽  
Svante Norgren ◽  
Karin Strigård ◽  
Anders Thörne ◽  
Hossein Fakhrai-Rad ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
Glucose Transport ◽  
Glucose Transporter ◽  
Age Groups ◽  
Tissue Growth ◽  
Adult Rats ◽  
Male Adult ◽  
Rat Adipocytes ◽  
Transporter Protein ◽  
Age Dependent

The regulation of adipocyte metabolism is of importance for adipose tissue growth and therefore also for the development of obesity. This study was designed to investigate the regulation of basal and insulin-induced lipogenesis, glucose transport, and glucose transporter protein expression in human and rat adipocytes from different age groups. The study included 21 infants, 21 children, nine adults, and 80 male weaned and 20 male adult Fischer rats. The lipogenesis experiments were performed under conditions at which glucose transport is rate limiting. Basal lipogenesis was approximately three times higher in infants and children than in adults, whereas insulin-induced lipogenesis was two times higher in infants than in children and adults. In rats, basal lipogenesis, insulin-induced lipogenesis, and insulin sensitivity were two times higher in weaned than in adult animals. Moreover, basal and insulin-induced glucose transport were two times higher in weaned than in adult rats. No differences were detected in GLUT1 or GLUT4 content between any of the age groups in human or in rat adipocytes. In conclusion, basal and insulin-stimulated lipogenesis are increased in adipocytes early in life. This may promote adipose tissue growth in early age. The data indicate that age-dependent variation in basal and insulin-stimulated lipogenesis is differently regulated.

scholarly journals Glucose Uptake in Trichoderma harzianum: Role of gtt1

2003 ◽  
Vol 2 (4) ◽  
pp. 708-717 ◽  
Author(s):  
Jesús Delgado-Jarana ◽  
Miguel Ángel Moreno-Mateos ◽  
Tahía Benítez
Keyword(s):  
Gene Expression ◽  
Glucose Uptake ◽  
Glucose Transport ◽  
Trichoderma Harzianum ◽  
Glucose Transporter ◽  
Biochemical Characterization ◽  
Carbon Sources ◽  
Low Carbon ◽  
Filamentous Ascomycete

ABSTRACT Using a differential display technique, the gene gtt1, which codes for a high-affinity glucose transporter, has been cloned from the mycoparasite fungus Trichoderma harzianum CECT 2413. The deduced protein sequence of the gtt1 gene shows the 12 transmembrane domains typical of sugar transporters, together with certain residues involved in glucose uptake, such as a conserved arginine between domains IV and V and an aromatic residue (Phe) in the sequence of domain X. The gtt1 gene is transcriptionally regulated, being repressed at high levels of glucose. When carbon sources other than glucose are utilized, gtt1 repression is partially alleviated. Full derepression of gtt1 is obtained when the fungus is grown in the presence of low carbon source concentrations. This regulation pattern correlates with the role of this gene in glucose uptake during carbon starvation. Gene expression is also controlled by pH, so that the gtt1 gene is repressed at pH 6 but not at pH 3, a fact which represents a novel aspect of the influence of pH on the gene expression of transporters. pH also affects glucose transport, since a strongly acidic pH provokes a 40% decrease in glucose transport velocity. Biochemical characterization of the transport shows a very low Km value for glucose (12 μM). A transformant strain that overexpresses the gtt1 gene shows a threefold increase in glucose but not galactose or xylose uptake, a finding which confirms the role of the gtt1 gene in glucose transport. The cloning of the first filamentous ascomycete glucose transporter is the first step in elucidating the mechanisms of glucose uptake and carbon repression in aerobic fungi.

Characterization of d-Glucose Transport across Equine Jejunal Brush Border Membrane Using the Pig as an Efficient Model of Jejunal Glucose Uptake

2013 ◽  
Vol 33 (6) ◽  
pp. 460-467 ◽  
Author(s):  
Adrienne D. Woodward ◽  
Ming Z. Fan ◽  
Raymond J. Geor ◽  
Laura J. McCutcheon ◽  
Nathanael P. Taylor ◽  
...  
Keyword(s):  
Glucose Uptake ◽  
Glucose Transport ◽  
Brush Border ◽  
Brush Border Membrane

D-glucose uptake is increased in jejunal brush-border membrane vesicles from hyperthyroid chicks

1989 ◽  
Vol 120 (4) ◽  
pp. 435-441 ◽  
Author(s):  
Hanna Debiec ◽  
Heide S. Cross ◽  
Meinrad Peterlik
Keyword(s):  
Glucose Uptake ◽  
Glucose Transport ◽  
Brush Border ◽  
Transmembrane Potential ◽  
Brush Border Membrane ◽  
Membrane Vesicles ◽  
Brush Border Membrane Vesicles ◽  
Potential Difference ◽  
Daily Injection ◽  
Transmembrane Potential Difference

Abstract. Jejunal brush-border membrane vesicles were harvested from 4-week old chicks whose thyroid status had been altered either by a daily injection of 20 μg T3 for 1 week or which through the preceding 4 weeks had received propylthiouracil and than had been repleted with either 20 or 80 μg T3 in divided doses within 48 h. T3 markedly stimulated D-glucose uptake in brush-border membrane vesicles in the presence of an outside/inside (100/0 mmol/l) Na+ gradient. T3 administration had no detectable influence on the Na+ permeability of the isolated vesicles. The effect of the thyroid hormone on Na+ gradient-driven D-glucose uptake was fully preserved at zero transmembrane potential difference. These findings exclude that T3 stimulates Na+-dependent D-glucose transport in the small intestine through changes of the electrochemical Na+ gradient or through alteration of the transmembrane potential difference. Tracer exchange experiments under equilibrium and voltageclamp conditions revealed a significantly shorter halftime of D-glucose uptake in brush-border membrane vesicles from T3-treated chicks. Kinetic analysis showed that T3 administration significantly increases the apparent maximal velocity of D-glucose transport in brushborder membrane vesicles, whereas the apparent Km values were virtually unaltered. From these data we conclude that T3 increases the activity of Na+-dependent D-glucose carriers in the brush-border membrane. This is interpreted as consistent with a greater rate of D-glucose absorption from the intestinal lumen under conditions of hyperthyroidism.

scholarly journals Proteolytic cleavage of cellubrevin and vesicle-associated membrane protein (VAMP) by tetanus toxin does not impair insulin-stimulated glucose transport or GLUT4 translocation in rat adipocytes

1997 ◽  
Vol 321 (1) ◽  
pp. 233-238 ◽  
Author(s):  
Eric HAJDUCH ◽  
J. Carlos ALEDO ◽  
Colin WATTS ◽  
Harinder S. HUNDAL
Keyword(s):  
Plasma Membrane ◽  
Membrane Protein ◽  
Glucose Uptake ◽  
Glucose Transport ◽  
Tetanus Toxin ◽  
Glucose Transporter ◽  
Detectable Effect ◽  
Glut4 Translocation ◽  
Rat Adipocytes ◽  
Isolated Rat

Acute insulin stimulation of glucose transport in fat and skeletal muscle occurs principally as a result of the hormonal induced translocation of the GLUT4 glucose transporter from intracellular vesicular stores to the plasma membrane. The precise mechanisms governing the fusion of GLUT4 vesicles with the plasma membrane are very poorly understood at present but may share some similarities with synaptic vesicle fusion, as vesicle-associated membrane protein (VAMP) and cellubrevin, two proteins implicated in the process of membrane fusion, are resident in GLUT4-containing vesicles isolated from rat and murine 3T3-L1 adipocytes respectively. In this study we show that proteolysis of both cellubrevin and VAMP, induced by electroporation of isolated rat adipocytes with tetanus toxin, does not impair insulin-stimulated glucose transport or GLUT4 translocation. The hormone was found to stimulate glucose uptake by approx. 16-fold in freshly isolated rat adipocytes. After a single electroporating pulse, the ability of insulin to activate glucose uptake was lowered, but the observed stimulation was nevertheless nearly 5-fold higher than the basal rate of glucose uptake. Electroporation of adipocytes with 600 nM tetanus toxin resulted in a complete loss of both cellubrevin and VAMP expression within 60 min. However, toxin-mediated proteolysis of both these proteins had no effect on the ability of insulin to stimulate glucose transport which was elevated approx. 5-fold, an activation of comparable magnitude to that observed in cells electroporated without tetanus toxin. The lack of any significant change in insulin-stimulated glucose transport was consistent with the finding that toxin-mediated proteolysis of both cellubrevin and VAMP had no detectable effect on insulin-induced translocation of GLUT4 in adipocytes. Our findings indicate that, although cellubrevin and VAMP are resident proteins in adipocyte GLUT4-containing vesicles, they are not required for the acute insulin-induced delivery of GLUT4 to the plasma membrane.

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