Glucose Uptake Activity Research Articles

The UPR reduces glucose metabolism via IRE1 signaling

Neurons are highly dependent on glucose. A disturbance in glucose homeostasis therefore poses a severe risk that is counteracted by activation of stress responses to limit damage and restore the energy balance. A major stress response that is activated under conditions of glucose deprivation is the unfolded protein response (UPR) that is aimed to restore proteostasis in the endoplasmic reticulum. The key signaling of the UPR involves the transient activation of a transcriptional program and an overall reduction of protein synthesis. Since the UPR is strategically positioned to sense and integrate metabolic stress signals, it is likely that - apart from its adaptive response to restore proteostasis - it also directly affects metabolic pathways. Here we investigate the direct role of the UPR in glucose homeostasis. O-GlcNAc is a post-translational modification that is highly responsive to glucose fluctuations. We find that UPR activation results in decreased O-GlcNAc modification, in line with reduced glucose metabolism. Our data indicate that UPR activation has no direct impact on the upstream processes in glucose metabolism; glucose transporter expression, glucose uptake and hexokinase activity. In contrast, prolonged UPR activation decreases glycolysis and mitochondrial metabolism. Decreased mitochondrial respiration is not accompanied by apoptosis or a structural change in mitochondria indicating that the reduction in metabolic rate upon UPR activation is a physiological non-apoptotic response. Metabolic decrease is prevented if the IRE1 pathway of the UPR is inhibited. This indicates that activation of IRE1 signaling induces a reduction in glucose metabolism, as part of an adaptive response.

Antioxidant, Glucose Uptake Stimulatory, α-Glucosidase and α-Amylase Inhibitory Effects of Myrianthus arboreus Stem Bark

Myrianthus arboreus is used traditionally in the management of diabetes in Ghana. The study seeks to evaluatethe antioxidant, glucose uptake, α-glucosidase and α-amylase inhibitory activities of the stem bark to support its folkloric use. The ethanol stem bark extract of M. arboreus was partitioned successively with petroleum ether, chloroform, ethyl acetate and n-butanol. The extract and fractions were evaluated for their glucose uptake effects in C2C12 myotubes and 3T3-L1 adipocytes. Their inhibitory action on α-glucosidase and α-amylase were also investigated whereas their antioxidant activities were evaluated using the DPPH and nitric oxide scavenging assays. The crude extract was further evaluated for its phenolic content, antioxidant capacity and reducing power. The stem bark extract significantly (P<0.05) stimulated glucose uptake in C2C12 myotubes and 3T3-L1 adipocytes when compared to control and also showed potent inhibitory activities against α-glucosidase and α-amylase with 11-fold and 5-fold better activity than acarbose respectively. The DPPH and nitric oxide radical scavenging effect of the extract were comparable with the ascorbic acid and α-tocopherol respectively. The extract had high phenol content with tannic acid equivalent of (114.70 ± 10.48) mg/g with an ascorbic acid equivalent of (98.34 ± 14.50) mg/g. The fractions demonstrated varying glucose uptake and enzyme inhibitory activities with the ethyl acetate fraction being the most potent. The ethyl acetate fraction demonstrated the highest scavenging effect on the DPPH and nitric oxide radicals. M. arboreus stem bark extract showed significant antioxidant, glucose uptake and enzyme inhibitory activities justifying its use in traditional medicine.

Luteolin-7-O-Glycosides from the Leaves of Centropogon cornutus (Campanulaceae)

Myrianthus arboreus is used traditionally in the management of diabetes in Ghana. The study seeks to evaluatethe antioxidant, glucose uptake, α-glucosidase and α-amylase inhibitory activities of the stem bark to support its folkloric use. The ethanol stem bark extract of M. arboreus was partitioned successively with petroleum ether, chloroform, ethyl acetate and n-butanol. The extract and fractions were evaluated for their glucose uptake effects in C2C12 myotubes and 3T3-L1 adipocytes. Their inhibitory action on α-glucosidase and α-amylase were also investigated whereas their antioxidant activities were evaluated using the DPPH and nitric oxide scavenging assays. The crude extract was further evaluated for its phenolic content, antioxidant capacity and reducing power. The stem bark extract significantly (P<0.05) stimulated glucose uptake in C2C12 myotubes and 3T3-L1 adipocytes when compared to control and also showed potent inhibitory activities against α-glucosidase and α-amylase with 11-fold and 5-fold better activity than acarbose respectively. The DPPH and nitric oxide radical scavenging effect of the extract were comparable with the ascorbic acid and α-tocopherol respectively. The extract had high phenol content with tannic acid equivalent of (114.70 ± 10.48) mg/g with an ascorbic acid equivalent of (98.34 ± 14.50) mg/g. The fractions demonstrated varying glucose uptake and enzyme inhibitory activities with the ethyl acetate fraction being the most potent. The ethyl acetate fraction demonstrated the highest scavenging effect on the DPPH and nitric oxide radicals. M. arboreus stem bark extract showed significant antioxidant, glucose uptake and enzyme inhibitory activities justifying its use in traditional medicine.

Antioxidant, Antiglycation, and Hypoglycaemic Effect of Seriphium plumosum Crude Plant Extracts.

Diabetes is a severely debilitating metabolic disorder characterised by chronic hyperglycaemia. Traditional medicinal plants provide an important avenue for the development of novel antidiabetic agents. The antidiabetic potential of the methanol, acetone, and hexane extracts of S. plumosum was assessed using different parameters. These included secondary metabolite quantification, hypoglycaemic, cytotoxic effects, and GLUT4 translocation augmentation on C2C12 cells. The methanol extract contained the highest amount of total phenolic and flavonoid compounds and showed enhanced antioxidant activity. The methanol extracts had the best DPPH scavenging (EC50 = 0.72 mg/ml) and ferric reducing powers (EC50 = 2.31 mg/ml). The hexane extract resulted in the highest glucose uptake activity of 35, 77% with respect to all other treatments after a 6-hour exposure period. Immunocytochemistry technique further revealed that the increased glucose utilisation may be due to increased membrane fused GLUT4 molecules in C2C12 cells. The hexane extract was also shown to upregulate the phosphorylation of p70 S6 kinase and Akt1/2. The study highlights a probable insulin-mimetic activity of the hexane extract via the augmentation of Akt1/2 phosphorylation which is involved in the GLUT4 translocation pathway. Furthermore, the study represents the first report on the cytotoxic effect, GLUT4 translocation, and glucose uptake potential of S. plumosum.

In vitro Antidiabetic Activity of Polar and Nonpolar Solvent Extracts from Leucas aspera (Willd.) Link Leaves.

Background:Diabetes mellitus is a chronic illness, and the management of diabetes is a global problem. Successful treatment is required to prevent complications and organ damages. Herbal medicines are having minimal adverse effects when compared to the available synthetic drugs to treat such chronic diseases and disorders.Objective:The present study was aimed to evaluate the antidiabetic and antioxidant activity of polar and nonpolar solvent extracts of Leucas aspera (Willd.) link leaves under in vitro models.Materials and Methods:The in vitro antidiabetic activity of petroleum ether (nonpolar) and ethanol (polar) extracts were evaluated in C2C12 cell lines by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay (cell viability method) and glucose uptake assay. 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging method used for the evaluation of in vitro antioxidant activity.Results:Both the polar and nonpolar solvent extracts of L. aspera had shown better antioxidant activity compared to standard (IC50 = 18.96 and 19.90 μg/mL, respectively). Petroleum ether extract exhibited better cytotoxic activity in C2C12 cell line compared to ethanol extract (concentration of test drug needed to inhibit cell growth by 50% 110.75 ± 5.5 vs. 415.25 ± 8.0 μg/mL) whereas ethanol extract showed enhanced glucose uptake activity than petroleum ether extract in C2C12 cell line at same concentrations.Conclusion:From our study results, we concluded that L. aspera (Willd.) link leaves had shown better antidiabetic activity and antioxidant activity under in vitro models. Nonpolar solvent extract produced slightly better activity than polar solvent extract. This study warrants further research and experiments on animal models.SUMMARY Petroleum ether extract of Leucas aspera (PELA) exhibited slightly higher 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging activity compared to ethanol extract of L. aspera (EELA)PELA exhibited better cytotoxic activity in C2C12 cell line compared to EELAEELA had shown enhanced glucose uptake activity than PELA in C2C12 cell line at same concentrationsL. aspera leaf extracts have potential scavenging of DPPH radicals similar to that of ascorbic acidOverall, PELA (nonpolar) produced slightly better antidiabetic activity and antioxidant activity than EELA (polar). Abbreviations Used: DM: Diabetes mellitus, EELA: Ethanol extract of Leucas aspera, L. aspera: Leucas aspera, PELA: Petroleum ether extract of Leucas aspera.

Triterpenoids Isolated from Ziziphus jujuba Enhance Glucose Uptake Activity in Skeletal Muscle Cells.

Jujube (Ziziphus jujuba Mill.), a traditional folk medicine and functional food in China and South Korea, is known for its beneficial properties, which include anti-cancer, anti-oxidative, and anti-obesity effects. To assess the anti-hyperglycemic effect of jujube in this study, we investigated the glucose uptake-promoting activity of jujube in rat L6 myotubes. After determining that the jujube extract induces muscle glucose uptake, we identified the following active compounds by bioassay-guided fractionation: betulonic acid, betulinic acid, and oleanonic acid. Ursonic acid, known to be present in jujube, was semi-synthesized from ursolic acid and also observed to enhance glucose uptake. These four triterpenic acids induced glucose uptake in a glucose transporter 4-dependent manner. Comparison experiments of jujube fruits from three countries, namely, China, South Korea, and Japan, revealed that Japanese jujube has a higher content of active triterpenoids and is the most potent enhancer of glucose uptake.

Carnosic acid as a component of rosemary extract stimulates skeletal muscle cell glucose uptake via AMPK activation.

Compounds that increase the activity of the energy sensor AMP-activated kinase (AMPK) have the potential to regulate blood glucose levels. Although rosemary extract (RE) has been reported to activate AMPK and reduce blood glucose levels in vivo, the chemical components responsible for these effects are not known. In the present study, we measured the levels of the polyphenol carnosic acid (CA) in RE and examined the effects and the mechanism of action of CA on glucose transport system in muscle cells. High performance liquid chromatography (HPLC) was used to measure the levels of CA in RE. Parental and GLUT4myc or GLUT1myc overexpressing L6 rat myotubes were used. Glucose uptake was assessed using [3 H]-2-deoxy-d-glucose. Total and phosphorylated levels of Akt and AMPK were measured by immunoblotting. Plasma membrane GLUT4myc and GLUT1myc levels were examined using a GLUT translocation assay. Statistics included analysis of variance (ANOVA) followed by Tukey's post-hoc test. At concentrations found in rosemary extract, CA stimulated glucose uptake in L6 myotubes. At 2.0μmol/L CA a response (226±9.62% of control, P=.001), similar to maximum insulin (201±7.86% of control, P=.001) and metformin (213±10.74% of control, P=.001) was seen. Akt phosphorylation was not affected by CA while AMPK and ACC phosphorylation was increased and the CA-stimulated glucose uptake was significantly reduced by the AMPK inhibitor compound C. Plasma membrane GLUT4 or GLUT1 glucose transporter levels were not affected by CA. Our study shows increased muscle cell glucose uptake and AMPK activation by low CA concentrations, found in rosemary extract, indicating that CA may be responsible for the antihyperglycemic properties of rosemary extract seen in vivo.

Participation of HIFs in the regulation of Sertoli cell lactate production

Hypoxia Inducible Factors (HIFs) are master regulators of glycolytic metabolism. HIFs consist of a constitutive HIFbeta (HIFβ) subunit and a HIFalpha (HIFα) subunit, whose half-life depends on prolyl-hydroxylases activity. Inhibition of prolyl-hydroxylases by hypoxia or transition metals, or augmentation of HIFα subunit levels by hormonal stimuli lead to a higher HIF transcriptional activity. On the other hand, it is well known that lactate produced by Sertoli cells is delivered to and used by germ cells as an energy substrate. The aim of this work was to investigate whether HIFs participate in the regulation of lactate production in rat Sertoli cells and whether they are involved in the FSH mechanism of action. In order to reach a higher HIF transcriptional activity, Sertoli cells were treated with CoCl2. We observed that a higher HIF transcriptional activity leads to an augmentation of: lactate production, glucose uptake and LDH activity. Besides, an increase in Glut1, Pkm2 and Ldha mRNA levels was observed. These findings suggested that HIFs may participate in the modulation of Sertoli cell nutritional function. As FSH regulates lactate production, we evaluated whether HIFs were involved in FSH action. Sertoli cells were stimulated with FSH in the absence or presence of LW6, a drug which promotes HIFα subunit degradation. On the one hand, we observed that FSH increases HIF1α protein, Hif1α and Hif2α mRNA levels and, on the other hand, that LW6 inhibits FSH-stimulated lactate production, glucose uptake, Glut1, Pkm2 and Ldha expression. It is proposed that HIFs are key components of the intricate pathways utilized by FSH to regulate the provision of lactate for germ cells. Considering that FSH is the master endocrine regulator of Sertoli cells, it is not surprising that this hormone may employ several regulatory mechanisms to fulfill the nourishing functions of this cell type.

Nutraceutical properties of cumin residue generated from Ayurvedic industries using cell line models.

Spent cumin (SC), generated from Ayurvedic industry, was evaluated for its nutraceutical potential in terms of antioxidant, antidiabetic and anticancer properties, and compared with that of the raw cumin (RC). SC and RC seeds were extracted with ethyl acetate (E) and methanol (M). SCM (methanol extract) were rich in p-coumaric acid, ferulic acid, ellagic acid and cinnamic acid (6.4445, 5.8286, 2.1519, 4.3085mg/g dry extract). SCM reduced Fe2+ ion (89.68µMAA/g dry weight), scavenged DPPH radical (IC50-238.6µg/mL), better α-amylase inhibition (IC50-337.22µg/mL) and glucose uptake activity in 30.7% of L6 cells. SCM inhibited viability, retarded migration area up to 41.02%, arrested cell cycle at S phase and induced apoptosis in 2.45% of HT29 colon cancer cells. The results indicated that dietary interventions using nutraceutical food formulation made out of SC can play a significant role in the prevention and management of degenerative diseases.

ANTI-DIABETIC AND ALDOSE REDUCTASE INHIBITORY POTENTIAL OF PSIDIUM GUAJAVA BY IN VITRO ANALYSIS

&lt;p&gt;&lt;strong&gt;Objective: &lt;/strong&gt;The objective of the present study was to determine the cellular level effect on glucose uptake and aldose reductase inhibitory activity of different extracts of traditional medicinal plant &lt;em&gt;Psidium guajava&lt;/em&gt;.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Methods: &lt;/strong&gt;&lt;em&gt;Psidium guajava&lt;/em&gt; was selected and subjected for successive extraction from non-polar to polar solvents and subjected to glucose uptake and aldose reductase inhibition assay.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Results: &lt;/strong&gt;Based on the results &lt;em&gt;Psidium guajava&lt;/em&gt;&lt;em&gt; &lt;/em&gt;methanolic extract (PGME) showed an enhancement in the glucose uptake and also up-regulates the gene and protein level expression of IRβ, IRS-1, PI3K and GLUT4. Wortmannin, a specific PI3K inhibitor confirms that the active PGME recruits glucose uptake through a PI3K dependent pathway. In the assay of aldose reductase inhibitory activity, the results suggested that PGME possesses a significant inhibitory effect.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Conclusion: &lt;/strong&gt;The result obtained in the present study focuses on the anti-diabetic effect of PGME by studying cellular level glucose uptake in L6 myotubes and aldose reductase inhibitory activity.&lt;strong&gt;&lt;/strong&gt;&lt;/p&gt;

Simvastatin inhibits glucose uptake activity and GLUT4 translocation through suppression of the IR/IRS-1/Akt signaling in C2C12 myotubes.

Simvastatin,a 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase inhibitor, is clinically used in the prevention and treatment of cardiovascular diseases. Numerous studies demonstrate that statins increase the risk of new-onset diabetes in long-term therapy, but mechanisms underpinning this effect are still unclear. Here, we investigated whether simvastatin inhibited the glucose uptake activity and the underlying mechanisms in C2C12 myotubes. Our studies showed that simvastatin significantly inhibited glucose uptake activity and GLUT4 translocation, whereas the effect was reversible with mevalonolactone (ML), which acts as an intermediate of cholesterol synthesis pathway. Mechanistically, the inhibition of glucose uptake and GLUT4 translocation elicited by simvastatin were associated with the suppression of the insulin receptor (IR)/IR substrate (IRS)/Akt signaling cascade. Simvastatin suppressed the phosphorylation of IR, IRS-1 and Akt, and total expression of IR or IRS-1, but did not affect Akt. Furthermore, simvastatin decreased Rac1 GTP binding. In conclusion, our findings indicate that simvastatin suppresses glucose uptake activity and GLUT4 translocation via IR-dependent IRS-1/PI3K/Akt pathway. These results provide an important new insight into the mechanism of statins on insulin sensitivity which may be associated with new-onset diabetes.

Lack of Skeletal Muscle IL-6 Affects Pyruvate Dehydrogenase Activity at Rest and during Prolonged Exercise.

Pyruvate dehydrogenase (PDH) plays a key role in the regulation of skeletal muscle substrate utilization. IL-6 is produced in skeletal muscle during exercise in a duration dependent manner and has been reported to increase whole body fatty acid oxidation, muscle glucose uptake and decrease PDHa activity in skeletal muscle of fed mice. The aim of the present study was to examine whether muscle IL-6 contributes to exercise-induced PDH regulation in skeletal muscle. Skeletal muscle-specific IL-6 knockout (IL-6 MKO) mice and floxed littermate controls (control) completed a single bout of treadmill exercise for 10, 60 or 120 min, with rested mice of each genotype serving as basal controls. The respiratory exchange ratio (RER) was overall higher (P<0.05) in IL-6 MKO than control mice during the 120 min of treadmill exercise, while RER decreased during exercise independent of genotype. AMPK and ACC phosphorylation also increased with exercise independent of genotype. PDHa activity was in control mice higher (P<0.05) at 10 and 60 min of exercise than at rest but remained unchanged in IL-6 MKO mice. In addition, PDHa activity was higher (P<0.05) in IL-6 MKO than control mice at rest and 60 min of exercise. Neither PDH phosphorylation nor acetylation could explain the genotype differences in PDHa activity. Together, this provides evidence that skeletal muscle IL-6 contributes to the regulation of PDH at rest and during prolonged exercise and suggests that muscle IL-6 normally dampens carbohydrate utilization during prolonged exercise via effects on PDH.

Two New Oleanane-type Triterpenoids from Methanolyzed Saponins of Momordica cochinchinensis

Two new oleanane-type triterpenoid saponins (1 and 2) were isolated from the methanolyzed total saponins of the seeds of Momordica cochinchinensis (Lour.) Spreng, together with 16 known compounds (3-18). Their structures were elucidated on the basis of detailed spectroscopic, including 1D and 2D NMR, mass spectrometric, methanolysis and LC-MS analysis. All the isolates were tested for their cytotoxic activities against five human cancer cell lines (HL-60, SMMC-7721, PANC-1, A-549, and SW-480) and the glucose uptake activity. The known compound 6 exhibited toxic effects against HL-60 with an IC50 value of 18.1 μM, while 10 showed cytotoxicity against SMMC-7721 and A-549 cell lines, with IC50 values of 34.4 and 32.8 μM, respectively. In addition, the new compound 2 showed glucose uptake activity with a glucose consumption value of 0.29 μM at 10 μM concentration.

Hypoglycemic Constituents Isolated from Trapa natans L. Pericarps.

Trapa natans L., called water chestnut or water caltrop, is a floating aquarium plant. Its fruits are widely used as food. Two new tannins, 1 and 2, one new neolignan, 14, one new norlignan, 17, and 20 known compounds, 3-13, 15, 16, and 18-24 were isolated from T. natans pericarps in this study. The 1, 2, 14, and 17 structures were elucidated using a chemical method and extensive spectral evidence. A series of hydrolyzable tannins, 1-8, a lignin, 13, a flavonoid, 16, a norlignan, 17, and phenolic compounds, 18, 20, 21, and 24 resulted in the enhanced glucose uptake activity in C2C12 myotubes. Compounds 4 and 5 significantly increased GLUT4 protein expression in C2C12 myotubes. In addition, 4 and 5 improved the phosphorylation of AMPK, AKT(S473), and AKT(T308). The involvement of AMPK and PI3K in the mechanism of action of compounds 4 and 5 was confirmed by use of AMPK and PI3K inhibitors, which completely suppressed the 4- and 5-mediated activities of glucose uptake in C2C12 myotubes. We also demonstrated that 4 and 5 could increase GLUT4 protein levels in plasma membranes.

Characterization of the role of sphingomyelin synthase 2 in glucose metabolism in whole-body and peripheral tissues in mice

Sphingomyelin synthase 2 (SMS2) is a proposed potential therapeutic target for obesity and insulin resistance. However, the contributions of SMS2 to glucose metabolism in tissues and its possible therapeutic mechanisms remain unclear. Thus, to determine whole-body glucose utilization and the contributions of each insulin-targeted tissue to glucose uptake, we performed a glucose kinetics study, using the radiolabeled glucose analog 18F-2-fluoro-2-deoxy-D-glucose (18F-FDG), in wild-type (WT) and SMS2 knockout (KO) mice. Insulin signaling was enhanced in the liver, white adipose tissue and skeletal muscle of SMS2 KO mice compared with those of WT mice. In addition, compared with in WT mice, blood clearance of 18F-FDG was accelerated in SMS2 KO mice when they were fed either a normal or a high fat diet. 18F-FDG uptake was also increased in insulin-targeted tissues such as skeletal muscle in the SMS2 KO mice. Whereas skeletal muscle sphingolipid content was not clearly affected, plasma levels of very long-chain fatty acid (VLCFA)-containing ceramides were markedly increased in SMS2 KO mice, compared with in WT mice. We also generated liver-conditional SMS2 KO mice and performed glucose and insulin tolerance tests on mice with a high fat diet. However, no significant effect was observed. Thus, our study provided evidence that genetic inhibition of SMS2 elevated glucose clearance through activation of glucose uptake into insulin-targeted tissues such as skeletal muscle by a mechanism independent of hepatic SMS2. Our findings further indicate that this occurs, at least in part, via indirect mechanisms such as elevation of VLCFA-containing ceramides.

Pilot-scale production and characterization of PEGylated human FGF-21 analog

FGF-21 has become a potential drug candidate for the treatment of type 2 diabetes. Previous studies have demonstrated that PEGylation of FGF-21 could significantly increase its in vivo half-life and provide its long-lasting blood glucose-lowering effect. To accelerate the development of PEGylated FGF-21 for clinical application as a long-acting antidiabetes drug, we prepared ahmFGF-21 (FGF-21 mutant) and PEGylated ahmFGF-21 in Escherichia coli Rosetta (DE3) by high cell density fermentation at a 50-L scale and pilot-scale purification. The physical and chemical properties of the purified proteins were analyzed in this study, including purity, molecular weight, isoelectric point, bacterial endotoxin, PEGylated site and second structure. As well as the in vitro glucose uptake activity and in vivo anti-diabetic effect were evaluated. Under the optimal fermentation and purification conditions, the average bacterial yield and expression level of target protein of three batches attained 52.2±4.6g/L and 223.92±5.41mg/L, respectively. The purity of pilot product was above 98% by SDS-PAGE (non-reducing or reducing) and HPLC (SEC or RPC) analysis and the final yield of PEGylated ahmFGF-21 was 87.91±1.49mg/L, which indicated that the pilot-scale production process was relatively stable. N-terminal sequencing and circular dichroism (CD) spectroscopy results showed that modification site of PEGylated ahmFGF-21 was alanine at N-terminal and the second structure of ahmFGF-21 had no obvious changes after PEGylation. Compared with ahmFGF-21, the long-acting hypoglycemic effect of PEGylated ahmFGF-21 prepared in the pilot-scale production was significantly improved in type 2 diabetic db/db mice. Our results demonstrated that the pilot-scale production process of PEGylated ahmFGF-21 was successfully established, which was very important for the clinical application.

Intracerebroventricular administration of okadaic acid induces hippocampal glucose uptake dysfunction and tau phosphorylation.

Intraneuronal aggregates of neurofibrillary tangles (NFTs), together with beta-amyloid plaques and astrogliosis, are histological markers of Alzheimer's disease (AD). The underlying mechanism of sporadic AD remains poorly understood, but abnormal hyperphosphorylation of tau protein is suggested to have a role in NFTs genesis, which leads to neuronal dysfunction and death. Okadaic acid (OKA), a strong inhibitor of protein phosphatase 2A, has been used to induce dementia similar to AD in rats. We herein investigated the effect of intracerebroventricular (ICV) infusion of OKA (100 and 200ng) on hippocampal tau phosphorylation at Ser396, which is considered an important fibrillogenic tau protein site, and on glucose uptake, which is reduced early in AD. ICV infusion of OKA (at 200ng) induced a spatial cognitive deficit, hippocampal astrogliosis (based on GFAP increment) and increase in tau phosphorylation at site 396 in this model. Moreover, we observed a decreased glucose uptake in the hippocampal slices of OKA-treated rats. In vitro exposure of hippocampal slices to OKA altered tau phosphorylation at site 396, without any associated change in glucose uptake activity. Taken together, these findings further our understanding of OKA neurotoxicity, in vivo and vitro, particularly with regard to the role of tau phosphorylation, and reinforce the importance of the OKA dementia model for studying the neurochemical alterations that may occur in AD, such as NFTs and glucose hypometabolism.

Radiogenomic Analysis Demonstrates Associations between (18)F-Fluoro-2-Deoxyglucose PET, Prognosis, and Epithelial-Mesenchymal Transition in Non-Small Cell Lung Cancer.

Purpose To investigate whether non-small cell lung cancer (NSCLC) tumors that express high normalized maximum standardized uptake value (SUVmax) are associated with a more epithelial-mesenchymal transition (EMT)-like phenotype. Materials and Methods In this institutional review board-approved study, a public NSCLC data set that contained fluorine 18 ((18)F) fluoro-2-deoxyglucose positron emission tomography (PET) and messenger RNA expression profile data (n = 26) was obtained, and patients were categorized on the basis of measured normalized SUVmax values. Significance analysis of microarrays was then used to create a radiogenomic signature. The prognostic ability of this signature was assessed in a second independent data set that consisted of clinical and messenger RNA expression data (n = 166). Signature concordance with EMT was evaluated by means of validation in a publicly available cell line data set. Finally, by establishing an in vitro EMT lung cancer cell line model, an attempt was made to substantiate the radiogenomic signature with quantitative polymerase chain reaction, and functional assays were performed, including Western blot, cell migration, glucose transporter, and hexokinase assays (paired t test), as well as pharmacologic assays against chemotherapeutic agents (half-maximal effective concentration). Results Differential expression analysis yielded a 14-gene radiogenomic signature (P < .05, false discovery rate [FDR] < 0.20), which was confirmed to have differences in disease-specific survival (log-rank test, P = .01). This signature also significantly overlapped with published EMT cell line gene expression data (P < .05, FDR < 0.20). Finally, an EMT cell line model was established, and cells that had undergone EMT differentially expressed this signature and had significantly different EMT protein expression (P < .05, FDR < 0.20), cell migration, glucose uptake, and hexokinase activity (paired t test, P < .05). Cells that had undergone EMT also had enhanced chemotherapeutic resistance, with a higher half-maximal effective concentration than that of cells that had not undergone EMT (P < .05). Conclusion Integrative radiogenomic analysis demonstrates an association between increased normalized (18)F fluoro-2-deoxyglucose PET SUVmax, outcome, and EMT in NSCLC. (©) RSNA, 2016 Online supplemental material is available for this article.

Curcumin directly inhibits the transport activity of GLUT1.

Curcumin, a major ingredient in turmeric, has a long history of medicinal applications in a wide array of maladies including treatment for diabetes and cancer. Seemingly counterintuitive to the documented hypoglycemic effects of curcumin, however, a recent report indicates that curcumin directly inhibits glucose uptake in adipocytes. The major glucose transporter in adipocytes is GLUT4. Therefore, this study investigates the effects of curcumin in cell lines where the major transporter is GLUT1. We report that curcumin has an immediate inhibitory effect on basal glucose uptake in L929 fibroblast cells with a maximum inhibition of 80% achieved at 75μM curcumin. Curcumin also blocks activation of glucose uptake by azide, glucose deprivation, hydroxylamine, or phenylarsine oxide. Inhibition does not increase with exposure time and the inhibitory effects reverse within an hour. Inhibition does not appear to involve a reaction between curcumin and the thiol side chain of a cysteine residue since neither prior treatment of cells with iodoacetamide nor curcumin with cysteine alters curcumin's inhibitory effects. Curcumin is a mixed inhibitor reducing the Vmax of 2DG transport by about half with little effect on the Km. The inhibitory effects of curcumin are not additive to the effects of cytochalasin B and 75μM curcumin actually reduces specific cytochalasin B binding by 80%. Taken together, the data suggest that curcumin binds directly to GLUT1 at a site that overlaps with the cytochalasin B binding site and thereby inhibits glucose transport. A direct inhibition of GLUT proteins in intestinal epithelial cells would likely reduce absorption of dietary glucose and contribute to a hypoglycemic effect of curcumin. Also, inhibition of GLUT1 activity might compromise cancer cells that overexpress GLUT1 and be another possible mechanism for the documented anticancer effects of curcumin.

Immunohistochemical expression of glucose transporter 1 in keratin-producing odontogenic cysts.

BackgroundKeratin-producing odontogenic cysts (KPOCs) are a group of cystic lesions that are often aggressive, with high rates of recurrence and multifocality. KPOCs included orthokeratinised odontogenic cyst (OOC) and parakeratotic odontogenic cysts, which are now considered true tumours denominated keratocystic odontogenic tumours (KCOTs). GLUT1 is a protein transporter that is involved in the active uptake of glucose across cell membranes and that is overexpressed in tumours in close correlation with the proliferation rate and positron emission tomography (PET) imaging results.MethodsA series of 58 keratin-producing odontogenic cysts was evaluated histologically and immunohistochemically in terms of GLUT1 expression. Different data were correlated using the beta regression model in relation to histological type and immunohistochemical expression of GLUT1, which was quantified using two different morphological methods.ResultsKPOC cases comprised 12 OOCs and 46 KCOTs, the latter corresponding to 6 syndromic and 40 sporadic KCOTs. GLUT1 expression was very low in OOC cases compared with KCOT cases, with statistical significant differences when quantification was considered. Different GLUT1 localisation patterns were revealed by immunostaining, with the parabasal cells showing higher reactivity in KCOTs. However, among KCOTs cases, GLUT1 expression was unable to establish differences between syndromic and sporadic cases.ConclusionsGLUT1 expression differentiated between OOC and KCOT cases, with significantly higher expression in KCOTs, but did not differentiate between syndromic and sporadic KCOT cases. However, given the structural characteristics of KCOTs, we hypothesised that PET imaging methodology is probably not a useful diagnostic tool for KCOTs. Further studies of GLUT1 expression and PET examination in KCOT series are needed to confirm this last hypothesis.