• Journal of the Korean Society of Food Science and Nutrition
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• v.43 no.7
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• pp.963-971
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• 2014

This study investigated the effects of exercise intensity on PGC-$1{\alpha}$, PPAR-${\gamma}$, and insulin resistance in skeletal muscle of high fat diet-fed Sprague-Dawley rats. Forty rats were randomly divided into five groups: sedentary control group (SED), high fat diet group (HF), high fat diet+low-intensity exercise group (HFLE, 22 m/min, 60 min, 6 days/week), high fat diet+moderate-intensity exercise group (HFME, 26 m/min, 51 min), and high fat diet+high-intensity exercise group (HFHE, 30 m/min, 46 min). After 4 weeks of high fat diet and endurance exercise training, the lipid profiles, insulin, and glucose concentrations were determined in plasma. PGC-$1{\alpha}$, PPAR-${\gamma}$, and GLUT-4 contents were measured in plantaris muscle. The rate of glucose transport in soleus muscle was determined under submaximal insulin concentration ($1,000{\mu}IU/mL$ insulin, 20 min) during muscle incubation. Plasma glucose during oral glucose tolerance test in HF was significantly greater than that in SED, and plasma glucose levels in the three exercise (EX) groups were significantly lower that those in SED and HF at 30 and 60 min, respectively (P<0.05). Plasma insulin levels in the EX groups were significantly reduced by 60 min compared to that in HF (P<0.05). The protein expression level of PGC-$1{\alpha}$ as well as muscle glucose uptake were significantly higher in SED and HF than those in the three EX groups (P<0.05), and HFHE showed significantly higher levels than HFLE and HFME. Expression levels of GLUT-4 and PPAR-${\gamma}$ were significantly higher in the HFLE, HFME, and HFHE groups compared to the SED and HF (P<0.05). Therefore, the results of this study indicate that 4 weeks of high fat diet significantly developed whole body insulin resistance but did not affect PGC-$1{\alpha}$, PPAR-${\gamma}$, or the glucose transport rate in skeletal muscle, and exercise training was able to attenuate deteriorated whole body insulin resistance due to high fat diet. In addition, high intensity training significantly affected PGC-$1{\alpha}$ expression and the glucose transport rate of skeletal muscle in comparison with low and middle training intensities.

• 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.

• Asian-Australasian Journal of Animal Sciences
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• v.26 no.8
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• pp.1189-1196
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• 2013

Adipose tissue development and function play a critical role in the regulation of energy balance, lipid metabolism, and the pathophysiology of metabolic syndromes. Although the effect of zinc ascorbate supplementation in diabetes or glycemic control is known in humans, the underlying mechanism is not well described. Here, we investigated the effect of a zinc-chelated vitamin C (ZnC) compound on the adipogenic differentiation of 3T3-L1 preadipocytes. Treatment with ZnC for 8 d significantly promoted adipogenesis, which was characterized by increased glycerol-3-phosphate dehydrogenase activity and intracellular lipid accumulation in 3T3-L1 cells. Meanwhile, ZnC induced a pronounced up-regulation of the expression of glucose transporter type 4 (GLUT4) and the adipocyte-specific gene adipocyte protein 2 (aP2). Analysis of mRNA and protein levels further showed that ZnC increased the sequential expression of peroxisome proliferator-activated receptor gamma ($PPAR{\gamma}$) and CCAAT/enhancer-binding protein alpha (C/$EBP{\alpha}$), the key transcription factors of adipogenesis. These results indicate that ZnC could promote adipogenesis through $PPAR{\gamma}$ and C/$EBP{\alpha}$, which act synergistically for the expression of aP2 and GLUT4, leading to the generation of insulin-responsive adipocytes and can thereby be useful as a novel therapeutic agent for the management of diabetes and related metabolic disorders.

• Journal of Life Science
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• v.19 no.5
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• pp.644-651
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• 2009

The objective of this study was to identify EXE (1 hr a day at 21 m/min for 5 day/wk, at 0 % grade for 6 wk) on myocardium glucose metabolic phenotypic proteins (AMPK-PGC-1${\alpha}$-GLUT-4) and HSP-60 protein expression after ischemia/reperfusion injury (IRI) in STZ-induced rats. EXE was performed using STZ-induced diabetic rats on a rodent treadmill (28 m/min, 1 hr/day, 5 day/wk for 6 wk). The results of this study suggest that i) serum insulin level was not changed among groups (p>l0.05). ii) the LVDP level increased significantly in the STZ-EXE-IRI group compared to the STZ-IRI group at 60 min (p<0.01), 70 min (p<0.05) and 80 min (p<0.05) after reperfusion, respectively, and iii) AMPK phosphorylation (p<0.01), PGC-1${\alpha}$ protein (p<0.001), GLUT-4 protein (p<0.001) and HSP-60 protein expressions (p<0.05) increased significantly in the STZ-EXE-IRI group compared to the STZ-IRI group. In conclusion, the findings of the present study reveal that EXE may provide therapeutic value to insulin dependent diabetic patients with peripheral insulin resistance and myocardium injury by improving glucose metabolic proteins (AMPK-PGC-1${\alpha}$-GLUT-4) and heat shock protein-60 (HSP-60), along with increasing LVDP levels and decreasing glucose levels. Therefore, EXE protects the STZ-induced diabetic myocardium injury against ischemia/ reperfusion injury.

• Biomolecules & Therapeutics
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• v.24 no.4
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• pp.363-370
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• 2016

Cardiovascular disease is the most common cause of death in diabetic patients. Hyperglycemia is the primary characteristic of diabetes and is associated with many complications. The role of hyperglycemia in the dysfunction of human cardiac progenitor cells that can regenerate damaged cardiac tissue has been investigated, but the exact mechanism underlying this association is not clear. Thus, we examined whether hyperglycemia could regulate mitochondrial dynamics and lead to cardiac progenitor cell dysfunction, and whether blocking glucose uptake could rescue this dysfunction. High glucose in cardiac progenitor cells results in reduced cell viability and decreased expression of cell cycle-related molecules, including CDK2 and cyclin E. A tube formation assay revealed that hyperglycemia led to a significant decrease in the tube-forming ability of cardiac progenitor cells. Fluorescent labeling of cardiac progenitor cell mitochondria revealed that hyperglycemia alters mitochondrial dynamics and increases expression of fission-related proteins, including Fis1 and Drp1. Moreover, we showed that specific blockage of GLUT1 improved cell viability, tube formation, and regulation of mitochondrial dynamics in cardiac progenitor cells. To our knowledge, this study is the first to demonstrate that high glucose leads to cardiac progenitor cell dysfunction through an increase in mitochondrial fission, and that a GLUT1 blocker can rescue cardiac progenitor cell dysfunction and downregulation of mitochondrial fission. Combined therapy with cardiac progenitor cells and a GLUT1 blocker may provide a novel strategy for cardiac progenitor cell therapy in cardiovascular disease patients with diabetes.

• The Korea Journal of Herbology
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• v.29 no.1
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• pp.45-52
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• 2014

Objectives : The aim of this study was to investigate the effects water extract of fermented new korean medicinal mixture, combinations of Mori Folium, Adenophorae Radix, Phllostachyos Folium and Citri Pericarpium (F-MAPC), on adipocyte differentiation, adipogenesis and glucose uptake using undiffernentiated 3T3-L1 adipocytes and L6 myoblasts. Methods : Each herb and those mixture were respectively fermented and then extracted with water. We carried on MTT assay for check-up on cell toxicity, Oil Red O staining for determination of cell differentiation and intracelluar adipogenesis. Western blot analysis for measurement of pAMPK and pACC, $C/EBP{\alpha}$, $PPAR{\gamma}$ and Glut-4 protein expressions were performed. Results : F-MAPC showed significant inhibitory activity on adipocyte differentiation in 3T3-L1 preadipocytes without affecting cell toxicity as assessed by measuring fat accumulation, and this effect was 2 fold higher in 0.2 mg/ml F-MAPC than that of the same dose of each fermented herbal extract alone. In addition, these effects were associated with modulation of adipogenic transcription factors, such as $C/EBP{\alpha}$, $PPAR{\gamma}$, as well as stimulated phosphorylations of AMPK and ACC. Translocation of Glut-4 was significantly increased by 10.2% in L6 cells treated with 0.2 mg/ml F-MAPC compared with that of control. Conclusions : These results demonstrate that F-MAPC may be an ideal candidate for therapy of obesity and diabetes by disturbing the differentiation into adipocytes, as well as the inducement of intramuscular glucose uptake from blood.

• Journal of the Korean Society of Food Science and Nutrition
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• v.46 no.5
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• pp.552-561
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• 2017

This study aimed to investigate glucose uptake mechanisms and metabolic mechanisms for absorbed glucose in HepG2 cells treated with Acanthopanax senticosus water extract (ASW). A colorimetric assay kit was used to measure polyphenol content, glucokinase (GK) activity, glucose uptake, glucose consumption in cell culture medium, and glycogen content. RT-PCR and western blotting were performed to examine changes in the expression levels of glucose transporter 2 (GLUT2), hepatocyte nuclear factor $1{\alpha}$ ($HNF-1{\alpha}$), phosphatidylinositol 3-kinase (PI3k), protein kinase B (Akt), phospho-AMP-activated protein kinase (AMPK), phosphoenolpyruvate carboxykinase, GK, and glycogen synthase kinase $3{\beta}$ ($GSK3{\beta}$). Increased glucose uptake upon ASW treatment was confirmed to result from increased expression of $HNF-1{\alpha}$, which is one of the transcription factors acting on the GLUT2 promoter. From the measurements of GK activity, we observed that ASW had an effect on glucose phosphorylation, and we also confirmed that increased AMPK phosphorylation promoted glycolysis and suppressed gluconeogenesis. We confirmed that the increase in glycogen upon ASW treatment was induced by activation of Akt by PI3k, followed by phosphorylation of $GSK3{\beta}$. This study demonstrates that ASW activates glucose metabolic mechanisms in liver cells and is therefore a potential candidate to alleviate diabetes.

• The Korean Journal of Physiology
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• v.27 no.2
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• pp.123-138
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• 1993

The mechanism of insulin action to increase glucose transport is attributed to glucose transporter translocation from intracellular storage pools to the plasma membrane in insulin-sensitive cells. The present study was designed to visualize the redistribution of the glucose transporter by means of an immunogold labelling method. Our data clearly show that glucose transporter molecules were visible by this method. According to the method this distribution of glucose transporters between cell surface and intracellular pool was different in adipocytes. The glucose transporter molecules were randomly distributed at the cell surface whereas the molecules at LDM were farmed as clusters. By insulin treatment the number of homogeneous random particles increased at the cell surface whereas the cluster forms decreased at the intracellular storage pools. It suggests that the active molecules needed to be evenly distributed far effective function and that the inactive molecules in storage pools gathered and termed clusters until being transferred to the plasma membrane.

• BMB Reports
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• v.45 no.6
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• pp.360-364
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• 2012

Uptake of circulating glucose into the cells happens via the insulin-mediated signalling pathway, which translocates the glucose transporter 4 (GLUT4) vesicles from the intracellular compartment to the plasma membrane. Rab GTPases are involved in this vesicle trafficking, where Rab GTPases-activating proteins (RabGAP) enhance the GTP to GDP hydrolysis. TBC1D4 (AS160) and TBC1D1 are functional RabGAPs in the adipocytes and the skeletonal myocytes, respectively. These proteins contain two phosphotyrosine-binding domains (PTBs) at the amino-terminus of the catalytic RabGAP domain. The second PTB has been shown to interact with the cytoplasmic region of the insulin-regulated aminopeptidase (IRAP) of the GLUT4 vesicle. In this study, we quantitatively measured the ${\sim}{\mu}M$ affinity ($K_D$) between TBC1D4 PTB and IRAP using isothermal titration calorimetry, and further showed that IRAP residues 1-49 are the major region mediating this interaction. We also demonstrated that the IRAP residues 1-15 are necessary but not sufficient for the PTB interaction.

• Journal of Food Hygiene and Safety
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• v.28 no.2
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• pp.152-157
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• 2013

We evaluated the anti-diabetic effects of Isaria tenuipes in diabetes mellitus type 2. For the experiments, the diabetic animal model OLETF rats were divided to 4 groups: Isaria tenuipes was administered mixed with the high fat diet 45% at dose levels of 0.0%, 0.1%, 1.0%, and 5.0% for 4 weeks. All animals have free access to water and high fat diet 45%. The diabetic clinical markers, including clinical signs, body weight and food intake, organ weights, blood glucose level, insulin level and HOMA-IR index, oral glucose tolerance test, GLUT4 mRNA and protein were measured at a time. After administration for 4 weeks, the blood glucose levels, insulin levels and HOMA-IR index of test groups were decreased compared with control group in dose-dependent manner. The body weight and diet consumptions were reduced in control group at 4 weeks. The treatments of Isaria tenuipes also showed high expression of GLUT4 mRNA and protein in the muscle of OLETF rats. The results suggest that Isaria tenuipes has anti-hyperglycemic effect attenuating blood glucose in the animal model of type 2 diabetes and might be useful as a functional diet for human diabetic diseases.