• Clinical and Experimental Pediatrics
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• v.59 no.sup1
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• pp.29-31
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• 2016

Glucose transport 1 (GLUT-1) deficiency is a rare syndrome caused by mutations in the glucose transporter 1 gene (SLC2A1) and is characterized by early-onset intractable epilepsy, delayed development, and movement disorder. De novo mutations and several hot spots in N34, G91, R126, R153, and R333 of exons 2, 3, 4, and 8 of SLC2A1 are associated with this condition. Seizures, one of the main clinical features of GLUT-1 deficiency, usually develop during infancy. Most patients experience brief and subtle myoclonic jerk and focal seizures that evolve into a mixture of different types of seizures, such as generalized tonic-clonic, absence, myoclonic, and complex partial seizures. Here, we describe the case of a patient with GLUT-1 deficiency who developed infantile spasms and showed delayed development at 6 months of age. She had intractable epilepsy despite receiving aggressive antiepileptic drug therapy, and underwent a metabolic workup. Cerebrospinal fluid (CSF) examination showed CSF-glucose-to-blood-glucose ratio of 0.38, with a normal lactate level. Bidirectional sequencing of SLC2A1 identified a missense mutation (c.1198C>T) at codon 400 (p.Arg400Cys) of exon 9.

• Journal of Microbiology and Biotechnology
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• v.23 no.5
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• pp.637-643
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• 2013

We have demonstrated that 1-deoxynojirimycin (DNJ) isolated from Bacillus subtilis MORI could enhance the levels of adiponectin and its receptors in differentiated 3T3-L1 adipocytes, which has been shown to be effective in lowering blood glucose levels and enhancing insulin sensitivity. DNJ was not toxic to differentiated 3T3-L1 adipocytes for up to a concentration of $5{\mu}M$. In terms of expression levels of adiponectin and its receptors (AdipoR1 and AdipoR2), DNJ in concentrations as low as $0.5{\mu}M$ elevated both mRNA and protein levels of adiponectin and transcript levels of AdipoR1 and AdipoR2. In addition, DNJ increased phosphorylation of 5' adenosine monophosphate-activated protein kinase (AMPK) in a statistically significant manner. Finally, treatment with DNJ resulted in increased mRNA expression of glucose transporter 4 (GLUT4), which encodes for a glucose transporter, along with a significant increase in glucose uptake into the adipocytes based on results of a 2-deoxy-D-[$^3H$] glucose uptake assay. Our findings indicate that DNJ may greatly facilitate glucose uptake into adipose tissues by increasing the action of adiponectin via its up-regulated expression as well as its receptor genes. In addition, the glucose-lowering effects of DNJ may be achieved by an increased abundance of GLUT4 protein in the plasma membrane, as a consequence of the increased transcript levels of the GLUT4 gene and the activation of AMPK.

• Journal of Ginseng Research
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• v.47 no.3
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• pp.420-428
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• 2023

Background: Ginsenoside F2 (GF2), a minor component of Panax ginseng, has been reported to possess a wide variety of pharmacological activities. However, its effects on glucose metabolism have not yet been reported. Here, we investigated the underlying signaling pathways involved in its effects on hepatic glucose. Methods: HepG2 cells were used to establish insulin-resistant (IR) model and treated with GF2. Cell viability and glucose uptake-related genes were also examined by real-time PCR and immunoblots. Results: Cell viability assays showed that GF2 up to 50 μM did not affect normal and IR-HepG2 cell viability. GF2 reduced oxidative stress by inhibiting phosphorylation of the mitogen-activated protein kinases (MAPK) signaling components such as c-Jun N-terminal kinase (JNK), extracellular signal-regulated kinase 1/2 (ERK1/2), and p38 MAPK, and reducing the nuclear translocation of NF-κB. Furthermore, GF2 activated PI3K/AKT signaling, upregulated the levels of glucose transporter 2 (GLUT-2) and GLUT-4 in IR-HepG2 cells, and promoted glucose absorption. At the same time, GF2 reduced phosphoenolpyruvate carboxykinase and glucose-6-phosphatase expression as well as inhibiting gluconeogenesis. Conclusion: Overall, GF2 improved glucose metabolism disorders by reducing cellular oxidative stress in IR-HepG2 cells via MAPK signaling, participating in the PI3K/AKT/GSK-3β signaling pathway, promoting glycogen synthesis, and inhibiting gluconeogenesis.

• The Korean Journal of Physiology and Pharmacology
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• v.18 no.4
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• pp.333-339
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• 2014

Exendin-4 (Ex-4), a glucagon-like peptide-1 receptor (GLP-1R) agonist, has been known to reverse hepatic steatosis in ob/ob mice. Although many studies have evaluated molecular targets of Ex-4, its mechanism of action on hepatic steatosis and fibrosis has not fully been determined. In the liver, glucose transporter 4 (GLUT4) is mainly expressed in hepatocytes, endothelial cells and hepatic stellate cells (HSCs). In the present study, the effects of Ex-4 on GLUT4 expression were determined in the liver of ob/ob mice. Ob/ob mice were treated with Ex-4 for 10 weeks. Serum metabolic parameters, hepatic triglyceride levels, and liver tissues were evaluated for hepatic steatosis. The weights of the whole body and liver in ob/ob mice were reduced by long-term Ex-4 treatment. Serum metabolic parameters, hepatic steatosis, and hepatic fibrosis in ob/ob mice were reduced by Ex-4. Particularly, Ex-4 improved hepatic steatosis by enhancing GLUT4 via GLP-1R activation in ob/ob mice. Ex-4 treatment also inhibited hepatic fibrosis by decreasing expression of connective tissue growth factor in HSCs of ob/ob mice. Our data suggest that GLP-1 agonists exert a protective effect on hepatic steatosis and fibrosis in obesity and type 2 diabetes.

• Journal of Ginseng Research
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• v.45 no.5
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• pp.565-574
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• 2021

Background: Saengmaeksan (SMS) is a traditional Korean medicine composed of three herbs, Panax ginseng, Schisandra chinensis, and Liriope platyphylla. SMS is used to treat respiratory and cardiovascular disorders. However, whether SMS exerts antihyperuricemic effects is unknown. Methods: Effects of the SMS extract in water (SMS-W) and 30% ethanol (SMS-E) were studied in a rat model of potassium oxonate-induced hyperuricemia. Uric acid concentrations and xanthine oxidase (XO) activities were evaluated in the serum, urine, and hepatic tissue. Using renal histopathology to assess kidney function and uric acid excretion, we investigated serum creatinine and blood urea nitrogen concentrations, as well as protein levels of renal urate transporter 1 (URAT1), glucose transporter 9 (GLUT9), and organic anion transporter 1 (OAT1). The effects of SMS on in vitro XO activity and uric acid uptake were also evaluated. The components of SMS were identified using Ultra Performance Liquid Chromatography (UPLC). Results: SMS-E reduced serum uric acid and creatinine concentrations, and elevated urine uric acid excretion. SMS-E lowered XO activities in both the serum and liver, and downregulated the expression of renal URAT1 and GLUT9 proteins. SMS-E reduced renal inflammation and IL-1b levels in both the serum and kidneys. SMS-E inhibited both in vitro XO activity and urate uptake in URAT1-expressing oocytes. Using UPLC, 25 ginsenosides were identified, all of which were present in higher levels in SMS-E than in SMS-W. Conclusion: SMS-E exhibited antihyperuricemic effects by regulating XO activity and renal urate transporters, providing the first evidence of its applicability in the treatment of hyperuricemia and gout.

• 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.

• Journal of Life Science
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• v.23 no.9
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• pp.1163-1169
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• 2013

Insulin induces glucose transporter 4 (GLUT4) translocation to the muscle cell surface. As fagopyritol has insulin-like effects, the effects of fagopyritol on GLUT4 translocation and filamentous (F) actin remodeling in L6-GLUT4myc skeletal muscle cells were investigated. Fagopyritol significantly increased plasma membrane GLUT4 levels compared with the basal control in L6-GLUT4myc myoblast cells. Phosphatidylinositol (PI) 3-kinase inhibitor (LY294002) treatment prevented GLUT4 translocation to the plasma membrane in the myoblasts. Fagopyritol treatment apparently stimulates F-actin remodeling in myoblasts. In addition, fagopyritol treatment induced GLUT4 translocation and F-actin remodeling in myotubes. Taken together, these results suggest that fagopyritol promotes GLUT4 translocation and F-actin remodeling by activating the PI 3-kinase-dependent signaling pathway.

• Biomedical Science Letters
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• v.12 no.1
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• pp.17-22
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• 2006

The baculovirus expression system is a powerful method for producing large amounts of the human erythrocyte-type glucose transport protein, heterologously. Characterization of the expressed protein is expected to show its ability to transport sugars directly. To achieve this, it is a prerequisite to know the properties of the endogenous sugar transport system in Spodoptera frugiperda Clone 21 (Sf21) cells, which are commonly employed as a host permissive cell line to support the baculovirus replication. The Sf21 cells can grow well on TC-100 medium that contains 0.1% D-glucose as the major carbon source, strongly suggesting the presence of endogenous glucose transport system. However, unlike the human glucose transport protein that has a broad substrate and inhibitor specificity, very little is known about the nature of the endogenous sugar transport system in Sf21 cells. In order to characterize further the inhibitor recognition properties of the Sf21 cell transporter, the ability of phloretin, cytochalasin B and D-fructose to inhibit 2-deoxy-D-glucose (2dGlc) transport was examined by measuring inhibition constants $(K_i)$. The $K_i's$ for reversible inhibitors were determined from plots of uptake versus inhibitor concentration. The 2dGlc transport in the Sf21 cells was very potently inhibited by phloretin, the aglucone of phlorizin with a $K_i$ similar to the value of about $2{\mu}M$ reported for inhibition of glucose transport in human erythrocytes. However, the Sf21 cell transport system was found to differ from the human transport protein in being much less sensitive to inhibition by cytochalasin B (apparent $K_i$ approximately $10\;{\mu}M$). In contrast, It is reported that the inhibitor binds the human erythrocyte counterpart with a $K_d$ of approximately $0.12\;{\mu}M$. Interestingly, the Sf21 glucose transport system also appeared to have high affinity for D-fructose with a $K_i$ of approximately 5mM, contrasting the reported $K_m$ of the human erythrocyte transport protein for the ketose of 1.5M.

• Journal of Microbiology and Biotechnology
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• v.26 no.4
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• pp.710-716
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• 2016

Gamma-aminobutyric acid (GABA) is a non-protein amino acid, which is an important inhibitor of neurotransmission in the human brain. GABA is also used as the precursor of biopolymer Nylon-4 production. In this study, the carbon flux from the tricarboxylic acid cycle was directed to the GABA shunt pathway for the production of GABA from glucose. The GABA shunt enzymes succinate-semialdehyde dehydrogenase (GabD) and GABA aminotransferase (GabT) were co-localized along with the GABA transporter (GadC) by using a synthetic scaffold complex. The co-localized enzyme scaffold complex produced 0.71 g/l of GABA from 10 g/l of glucose. Inactivation of competing metabolic pathways in mutant E. coli strains XBM1 and XBM6 increased GABA production 13% to reach 0.80 g/l GABA by the enzymes co-localized and expressed in the mutant strains. The recombinant E. coli system developed in this study demonstrated the possibility of the pathway of the GABA shunt as a novel GABA production pathway.

• Journal of the Korean Society of Food Culture
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• v.24 no.2
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• pp.219-223
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• 2009

We investigated the effect of Takju lees extract on blood glucose levels in the db/db mice (a murine model of type 2 diabetes mellitus). We fed 40 male db/db mice a control diet (G0, AIN93G) and experimental diets containing 1% (G1), 2% (G2), or 4% (G4) Takju lees extract for 4 weeks. We found no difference in food intake and body weight gain among the animal groups. In the G1 and G2 groups, plasma glucose levels decreased significantly between Days 10 and 21 compared with the G0 group. However, we found no difference in plasma glucose levels between groups G4 and G0. The change in insulin concentrations was not significant among these animal groups, and we found no significant difference in glucose transporter 4 (GLUT4) expression in the soleus muscle. These results suggest that the Takju lees extract has a beneficial effect in animals with type 2 diabetes.