• Journal of Microbiology and Biotechnology
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• v.14 no.3
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• pp.450-455
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• 2004

A reducing glucose-carrying polymer, called poly [3-O-(4'-vinylbenzyl)-D-glucose］(PVG), was interacted with HepG2 cells including a type-l glucose transporter (GLUT-1) on the cell membrane. The cooperative interaction between a number of GLUT-1s and a number of reducing 3-O-methyl-D-glucose moieties on the PVG polymer chain was found to be responsible for the increase in the interaction with HepG2 cells. The affinity between the cells and the PVG was studied using RITC-labeled glycopolymers. The specific interaction between the GLUT-1 on HepG2 cells and the PVG polymer carrying reducing glucose moieties was suppressed by the inhibitors, phloretin, phloridzin, and cytochalasin B. Direct observation by confocal laser microscopy with the use of RITC-labeled PVG and pretreatment of HepG2 cells with the inhibitors demonstrated that the cells interacted with the soluble form of the PVG polymer via GLUT-1, while fluorescence labeling of the cell surface was prevented after pretreatment with the inhibitors of GLUT-1.

• Journal of Life Science
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• v.15 no.1 s.68
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• pp.87-93
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• 2005

This study investigated the response of GLUT -4 and GRP-78 expression in soleus muscle of streptozotocin-induced diabetic rats by imposing different exercise intensities. F344 rats were randomly divided into 4 groups (n=15 in each group): Control (Control), diabetes-operation (DO), diabetes with low intensity exercise (DLE) and diabetes with high intensity exercise (DHE). The rats in DLE and DHE groups were exercised for 8 weeks by treadmill running. Blood glucose levels in DO were significantly higher compared to that in NORMAL whereas DLE showed the most lowest level in blood glucose among diabetic groups. Diabetic groups exhibited significantly lower level in insulin change and DLE showed significantly higher insulin level among diabetic groups. GRP-78 in DO was significantly $(167.05\%)$ higher than that in Control. GRP-78 in DLE was $139.41\%$ which is significantly higher compared to Control but when compared to DO and DHE, it was significant low. GRP-78 in DHE was $194.64\%$ which doubled the protein level in Control and showed the most highest level in all groups. GLUT-4 in DO was significantly $(33.58\%)$ higher compared to Control. GLUT-4 in DLE showed $124.58\%$ which was significant high compared to Control, DO and DHE. GLUT-4 in DHE showed $26.91\%$ compared to Control and was the most lowest level among all groups. It seems clear that chiefly low intensity exercise benefits diabetic patients in controlling blood glucose. It was concluded that low intensity exercise induces translocation of GLUT-4 which results in increased blood inflow, thus GRP-78 expression is decreased.

• Korean Journal of Exercise Nutrition
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• v.13 no.1
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• pp.1-7
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• 2009

It has been shown that both caloric restriction and exercise, enhances glucose uptake through translocation of GLUT-4 protein. It remains unclear how exercise and caloric restriction affect the changes in VAMP (vesicle-associated membrane protein) in skeletal muscle and GLUT-2 in liver. This study investigated the effects of exercise training and caloric restriction on the expressions of glucose transport relating proteins in muscle and liver tissues in diabetic rats. Forty male Sprague-Dawley rats (250±10 g; 8 week in age) were assigned equally to four different groups; control (C), exercise only (E), dietary restriction only (D) and dietary restriction and exercise (DE). Daily food consumption was monitored to establish baseline intake. Both C and E groups consumed baseline food intake while D and DE groups were provided with only 60% of baseline total food intake. Forty-eight hours after intraperitoneal injection of STZ (50 mg/kg), diabetes was confirmed (8-hr fasting blood glucose levels ≥300 mg/dl). Rats in the E and DE groups exercised on a motorized treadmill for 30 min/d, 5 days/week for 4 weeks (5 min running at 3 m/min, 0% grade; 8 m/min for the next 5min, and then 15 m/min for 20 min). Rats were sacrificed 48 hrs after the last bout of exercise. Soleus muscle and liver were extracted to analyze for GLUT-4, VAMP-2, and GLUT-2, respectively. All variables were analyzed using the Western Blotting technique. All values were expressed as optical volume measured by optical density. A Two-way ANOVA was used to examine the difference between groups and applied Duncan's test for post-hoc. No significant differences in GLUT-2 expression were found among groups. However, E (280133±13228 arbitrary units{AU}) and DE (268833±14424 AU) groups showed significantly higher (p<.001) levels of GLUT-4 as compared with C (34461±2099 AU) and D groups (27847±703 AU). VAMP-2 protein expression increased (p<.001) in E (184137±7803 AU) and DE (189800±10856 AU) groups as compared to C (74201±8296AU) and D (72967±863 AU) groups. These results suggest that either exercise with or without caloric restriction increases the up-regulation of GLUT-4 and VAMP-2 in skeletal muscle of diabetic rats. However, GLUT-2 protein in liver was not affected by either exercise or exercise with caloric restriction.

• Journal of Life Science
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• v.31 no.1
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• pp.1-9
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• 2021

Brown seaweeds have been shown to decrease blood glucose levels and improve insulin sensitivity previously. In this study, we investigated the effect of fucoidan, a complex polysaccharide derived from brown seaweeds, on glucose uptake to improve insulin resistance, and examined its mechanism of action in 3T3-L1 adipocytes. We observed that fucoidan significantly increased glucose uptake and it was related to an increased expression of plasma membrane-glucose transporter 4 (PM-GLUT4) in 3T3-L1 adipocytes. Fucoidan treatment increased the activation of phosphatidylinositol-3-kinase (PI3K) and the phosphorylation of insulin receptor substrate 1 (IRS1tyr) compared with that of the control cells. Fucoidan also promoted the phosphorylation of Akt and protein kinase C (PKC)-λ/ζ compared to that of the control cells. Moreover, fucoidan significantly upregulated acetyl-CoA-carboxylase (ACC) and adenosine monophosphate - activated protein kinase (AMPK) phosphorylation. As a result, translocation of GLUT4 was significantly enhanced in 3T3-L1 adipocytes, which significantly promoted glucose uptake via the PI3K/AMPK pathways. The elevation of glucose uptake by fucoidan was blocked by inhibitor of PI3K and inhibitor of AMPK in 3T3-L1 adipocytes. These findings indicate that fucoidan might ameliorate glucose uptake through GLUT4 translocation to the plasma membrane by activating the PI3K/Akt and AMPK pathways in 3T3-L1 adipocytes. Fucoidan is thought to be of high material value to diabetes treatments and functional foods.

• The Korean Journal of Physiology and Pharmacology
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• v.5 no.2
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• pp.183-188
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• 2001

To elucidate antidiabetic effect and mechanism(s) of acarbose in a polygenic spontaneous hyperglycemic and hyperinsulinemic diabetic animal model, $KKA^y$ mice, acarbose was administered orally for 4 weeks and effects on body weight, plasma glucose and insulin levels, genetic expressions of intestinal sucrase-isomaltase (SI), sodium-glucose cotransporter (sGLT1) and glucose transporter in quadriceps muscle (GLUT4) were examined in this study. Although no differences in body weight were detected between control and acarbose-treated groups, plasma glucose level in acarbose-treated group was markedly reduced as compared to the control. In the mechanism study, acarbose downregulated the SI and SGLT1 gene expressions, and upregulated the GLUT4 mRNA and protein expressions when compared to the control group. In conclusion, the data obtained strongly implicate that acarbose can prevent the hyperglycemia in $KKA^y$ mice possibly through blocking intestinal glucose absorption by downregulations of SI and sGLT1 mRNA expressions, and upregulation of skeletal muscle GLUT4 mRNA and protein expressions.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.1
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• pp.147-151
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• 2016

Oral squamous cell carcinoma (OSCC) is the most common malignancy of the oral cavity and some of these have been documented in association or preceded by oral epithelial dysplasia (OED). Aggressive cancers with fast growth have demonstrated overexpression of some glucose transporters (GLUTs). Thus, the aim of this study was to analyze the immunohistochemical expression of the glucose transporter, GLUT-1, in OEDs and OSCCs, seeking to better elucidate the biological behavior of neoplasias. Fifteen cases were selected this research of both lesions. Five areas were analyzed from each case by counting the percentage of positive cells at 400x magnification. Immunoreactivity of GLUT-1 was observed in 100% of the samples ranging from 54.2% to 86.2% for the OSCC and 73.9% to 97.4% for the OED. Statistical test revealed that there was greater overexpression of GLUT-1 in OED than the OSCC (p=0.01). It is believed the high expression of GLUT-1 may reflect the involvement of GLUT-1 in early stages of oral carcinogenesis.

• Journal of Life Science
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• v.14 no.5
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• pp.741-746
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• 2004

This study investigated the response of GLUT-4 and GRP-78 protein expression in soleus muscle of Streptozotocin-induced diabetic rats with caffeine oral administration by imposing different exercise intensities. Rats were randomly divided into 5 groups (n=6 in each group): diabetic group (D), diabetic-caffeine group (DC), diabetic-caffeine group with low intensity exercise (DCL), diabetic-caffeine group with moderate intensity exercise (DCM) and diabetic-caffeine group with high intensity exercise (DCH). The rats in DCL, DCM and DCH groups were exercised acutely by treadmill running for 8 meter/m, 16 meter/m and 25 meter/m, respectively. Little difference in GLUT-4 protein expression was shown in DC and DCL compared to D. GLUT-4 protein expression was decreased in DCM and increased in DCH was observed. GRP-78 protein expressions in DCL, DCM and DCH were little lower than that of D. An increase in GRP-78 protein was observed in DC. Improved insulin sensitivity with acute high intensity exercise gives the rats important therapy that lowers insulin requirement. This improvement of insulin sensitivity for glucose transport in skeletal muscle results from translocation of the GLUT-4 protein from the endoplasmic reticilum to the cell surface and increase in total quantity of GLUT-4 protein. It is not clear what mechanism reduced GRP-78 protein level in exercise group. It is merely conjectured that caffeine-induced lipolysis provided cells with energy in abundance and this relieved stress which cells are subjected to receive when performing exercise.

• Tuberculosis and Respiratory Diseases
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• v.45 no.4
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• pp.760-765
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• 1998

Background: Glucose uptake has been found to be increased in cancer cells, and FDG-PET imaging is used for diagnosis of cancer using this phenomenon. However, the exact mechanism of increased glucose uptake in cancer cells has not been clarified. Recent studies demonstrated the presence of glucose transporter(GLUT) mRNA expression in gastrointestinal cancer and head and neck cancer, and suggested that GLUT may be associated with glucose uptake in cancer cells. In lung cancer cells, glucose metabolism is also known to be increased. We evaluated GLUT mRNA expression in human lung cancer cell lines in order to find out the mechanism of increased glucose uptake in lung cancer. Method: Total RNA was isolated from 15 human lung cancer cell lines and immortalized bronchial epithelial cell line(BEAS-2B). After electrophoresis of $20{\mu}g$ total RNA, Northern blot analysis was done using GLUT1 cDNA and GLUT3 cDNA as probes. Results: Thirteen of 14 human lung cancer cell lines expressed GLUT1 mRNA and 10 of 14 human lung cancer cell lines expressed GLUT3 mRNA. Eight human lung cancer cell lines expressed both GLUT mRNAs. BEAS-2B expressed GLUT1 mRNA and did not express detectable GLUT3 mRNA. Conclusion: The increase of glucose metabolism in lung cancer may be associated with GLUT1 and GLUT3 expression.

• Korean Journal of Exercise Nutrition
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• v.13 no.2
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• pp.131-140
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• 2009

The aim of this study was to investigate the expression of PPAR-α, -β/δ, -γ, PGC-1α, GLUT-4 and p-AMPK-α₂ protein in the skeletal muscle of diabetic induced-rats by endurance training combined with rosiglitazone. The expression of PPAR-α, -β/δ, -γ, PGC-1α, GLUT-4 and p-AMPK-α₂ protein in red and white gastrocnemius by western blotting. The body weight was higher in diabetic induced-rats compared to the normal rats and after the treatment of exercise combined with rosiglitazone was significantly reduced in the all group. The levels of blood glucose was higher in diabetic induced-rats compared to the normal rats and after the treatment of exercise combined with rosiglitazone was significantly reduced in the all group. The expression of PPAR-α, -γ, PGC-1α in skeletal muscle of diabetic induced-rats were increased all groups and increased significantly in the group with exercise combined with rosiglitazone. The expression of GLUT-4 and p-AMPK-α₂ protein in the skeletal muscle of diabetic induced-rats were increased all groups and increased significantly in the group with exercise combined with rosiglitazoneI. These results suggest that exercise training and rosiglitazone may act as complementary therapies for the treatment of insulin rasistance.

• Asian-Australasian Journal of Animal Sciences
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• v.20 no.8
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• pp.1297-1304
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• 2007

We conducted a series of investigations in order to elucidate role of nutritional status in regulating GLUT expression and energy metabolism in porcine muscle. Firstly, the role of mild undernutrition in regulating muscle GLUT gene expression and function was studied in growing pigs (3 wk of age) on a high (H) or low (L) food intake (H = 2L) at $35^{\circ}C$ or $26^{\circ}C$. Low food intake selectively upregulates GLUT1 and GLUT4 gene expression; mRNA levels were elevated in longissimus dorsi (L. dorsi) and rhomboideus muscles but not in diaphragm or cardiac muscles. Our next step was to determine whether dietary lysine, a major primary limiting amino acid in diets for pigs, affects muscle GLUT4 expression. Pigs of 6 wk of age were pair-fed a control or low lysine (LL) diet. The control diet contained optimal amounts of all essential amino acids, including 1.15% lysine. The LL diet was similar but contained only 0.70% lysine. GLUT4 mRNA expression was upregulated by the LL diet in L. dorsi and rhomboideus muscles, whereas that in cardiac muscle was unaffected. GLUT4 protein abundance was also higher in rhomboideus muscle of animals on the LL diet. We conducted another investigation in order to elucidate effects of the LL diet on post-GLUT4 glucose metabolism. Activity of hexokinase was unaffected by dietary lysine levels while that of citrate synthase was higher both in L. dorsi and rhomboideus muscles of pigs fed on the LL diet. Glucose 6-phosphate content was higher in L. dorsi msucle in the LL group. Glycogen content was higher both in L. dorsi and rhomboideus muscles in the LL group. Further, we determined the effects of dietary lysine levels on accumulation of intramuscular fat (IMF) in L. dorsi muscle of finishing pigs. A low lysine diet (lysine content was 0.40%) meeting approximately 70% of the requirement of lysine was given to finishing pigs for two months. IMF contents in L. dorsi of the pigs given the low lysine diet were twice higher than those of the pigs fed on a control diet (lysine content was 0.65%). Finally, we proved that a well known effect of breadcrumbs feeding to enhance IMF of finishing pigs could be attributed to shortage of amino acids in diets including breadcrumbs.