Cellular Glucose Transport Research Articles

Adipocyte traits limiting cellular insulin responsiveness and glucose transport.

Adipocyte dysfunction is a hallmark of systemic insulin resistance. Insulin-responsive glucose transporter 4 (GLUT4) is downregulated in the insulin resistant state, and cellular insulin responsiveness varies depending on fat depot origin and degree of adipose expansion. Here, we have resolved factors limiting cellular insulin responsiveness, by examining adipocyte function and traits related to glucose transport at the cellular level. Subcutaneous (inguinal) and visceral (epididymal) adipocytes were isolated from C57BL/6J mice fed either chow or high-fat diet. Cell size was determined using coulter counter method, glucose uptake and cytosolic volume were assessed using glucose tracer assays. Total and GLUT4 protein content expressions were determined by Western blot. We found that basal glucose uptake per cell was preserved independent of diet or fat depot origin. Insulin-stimulated glucose uptake per cell was sustained in visceral adipocytes but decreased with adipose expansion in subcutaneous adipocytes. In parallel, the cytosolic space and total protein increased proportionally to total cellular volumetric expansion in visceral, but not in subcutaneous, adipocytes, whereas GLUT4 content decreased exclusively in expanding subcutaneous adipocytes. Together, these data support the existence of distinct phenotypic adipocyte traits that could limit cellular insulin responsiveness. Potentially, these characteristics account for fat depot-specific differences related to glucose transport capacity.NEW & NOTEWORTHY This work illustrates that adipocyte characteristics related to fat depot origin rather than adipocyte size per se limit cellular insulin responsiveness and glucose uptake in male C57BL/6J mice. These findings contribute to the overall understanding of factors limiting adipocyte function and how adipose progression affects insulin response and glucose transport capacity differently in diverse fat depots. Future studies examining whether the proposed characteristics hold true in adipocytes derived from female mice or human origin are needed.

Photodynamic therapy enhances the cytotoxicity of temozolomide against glioblastoma via reprogramming anaerobic glycolysis

The successful application of photodynamic therapy in the treatment of glioma (CNS WHO grade 4) depends in large part to the effect of killing cells in the infiltrating area after tumor had been removed, when combined with radiotherapy, chemotherapy, and targeted drug therapy. The purpose of this study was to investigate the potential mechanism of TMZ's involvement in the glioma's glycolytic metabolic pathway during photodynamic therapy. The low dose of photodynamic therapy treatment on the cell viability of gliomas was investigated by CCK8. Alterations in reactive oxygen species were detected by flow cytometer. The differentially expressed proteins related to glucose transporter 1 (GLUT-1), matrix metalloproteinase-2 (MMP-2)/actively MMP-2 and apoptosis-associated caspase-3/cleaved caspase-3 were evaluated by Western Blot experiment. Additionally, transmission electron microscopy observed apoptosis, necrosis and the changes of the ultrastructure in U251 cells. In addition, antitumor effects in vivo were tested using orthotopic BALB/c mice with the glioma U87 model. The findings showed that low dose PDT affected mitochondrial function by inducing radical oxygen, hindered cellular glucose transport and metabolism, and induced apoptosis. The results also showed that cell viability considerably decreased and increased cell apoptosis under the PDT therapy. The HIF-1/GLUT-1 axis enhanced the cytotoxicity of temozolomide in gliomas as a result of PDT treatment, which was influenced by ROS. As a result, this study presents PDT as a potential therapeutic approach for treating malignant glioma, and enhanced antitumor effect of TMZ by inhibiting glycolytic pathway.

Targeting Glucose Transport Proteins for Diabetes Management: Regulatory Roles of Food-Derived Compounds.

With the rapid rise in prevalence, diabetes mellitus is one of the leading causes of mortality worldwide. Impaired cellular glucose transport is a major contributor to diabetes progression and, thus, an important target for treatment. Functional foods are a rich source of antidiabetic agents. These compounds target multiple physiological contributors to diabetes with lower risk for side effects. This perspective highlights recent advances in food-derived compounds that regulate the gene expression or activity of glucose transport proteins (SGLT1, SGLT2, GLUT1, GLUT2, and GLUT4) and provides insights for future research on targeting the transporters as a promising antidiabetic mechanism of nutraceutical compounds.

Micronutrients impact the gut microbiota and blood glucose.

Micronutrients influence hormone action and host metabolism. Dietary minerals, trace elements, and vitamins can alter blood glucose and cellular glucose metabolism, and several micronutrients are associated with the risk and progression of type 2 diabetes. Dietary components, microbes, and host immune, endocrine, and metabolic responses all interact in the intestine. There has been a focus on macronutrients modifying the host-microbe relationship in metabolic disease. Micronutrients are positioned to alter host-microbe symbiosis that participates in host endocrine control of glucose metabolism. Minerals and trace elements can alter the composition of the intestinal microbiota, gut barrier function, compartmentalized metabolic inflammation, cellular glucose transport, and endocrine control of glucose metabolism, including insulin and thyroid hormones. Dietary vitamins also influence the composition of the intestinal microbiota and vitamins can be biotransformed by gut microbes. Host-microbe regulation of vitamins can alter immunity, lipid and glucose metabolism, and cell fate and function of pancreatic beta cells. Causal effects of micronutrients in host-microbe metabolism are still emerging, and the mechanisms linking dietary excess or deficiency of specific micronutrients to changes in gut microbes directly linked to metabolic disease risk are not yet clear. Dietary fiber, fat, protein, and carbohydrates are key dietary factors that impact how microbes participate in host glucose metabolism. It is possible that micronutrient and microbiota-derived factors also participate in host-microbe responses that tip the balance in the endocrine control of host glucose metabolism. Dietary micronutrients should be considered, tested, and controlled in pre-clinical and clinical studies investigating host-microbe factors in metabolic diseases.

Reduced cellular glucose transport confers natural protection against dextrose-induced superoxide generation and endoplasmic reticulum stress in domestic hen.

Normal blood glucose levels in avian species are two to fourfold higher than that in humans and the higher blood glucose levels in birds do not cause adverse effects. Endothelial cells isolated from the aorta of the domestic hen (Gallus gallus domesticus) and chicken aortic smooth muscle cells (CAOSMC) were compared to human coronary artery endothelial cells (HCAEC) and human primary aortic smooth muscle cells (HASMC). Superoxide (SO) generation was measured using a superoxide‐reactive probe. ER stress was measured using the placental alkaline phosphatase assay (ES‐TRAP). Glucose transport kinetics were determined using the 3H‐2‐deoxyglucose tracer. Dextrose‐induced SO generation and ER stress were significantly blunted in avian endothelial cells compared to human cells. The Vmax of glucose uptake (in nmoles/mg protein/min) in avian endothelial cells (0.0018 ± 0.0001) and smooth muscle cells (0.0015 ± 0.0007) was approximately 18–25 fold lower compared to the Vmax in HCAEC (0.033 ± 0.0025) and HASMC (0.038 ± 0.004) (all p < 0.0001). The Michaelis–Menten constant (Km) of transport was also significantly different (p < 0.0001) in avian species. The relative resistance of avian cells to dextrose‐induced oxidative stress and ER stress is mostly the result of reduced cellular dextrose transport.

Abstract 15820: Differential Myocardial Gene Expression of Glucose Transporters in Heart Transplant Recipients With and Without Diabetes Mellitus

Introduction: The Sodium Glucose cotransporter (SGLT) and glucose transporters(GLUTs) play a crucial role in cellular glucose transport. Although experimental data have shown differential regulation of GLUT4 and SGLT in diabetic cardiomyopathy, the impact of diabetes mellitus (DM) upon myocardial glucose transporters in humans remains undetermined. Aim: To better understand the impact of elevated glucose levels upon myocardial expression of glucose transporters, the endomyocardial gene expression of GLUT1, GLUT4 and SGLT1 was investigated in heart transplant(HTx) recipients, with and without DM, who received a heart from a DM- donor. Methods: At baseline(BL), immediately after HTx and 12 ± 2 months(FU) later, serial endomyocardial biopsies were procured in 26 Htx pts, free of clinical or histological rejection, at time of routine surveillance biopsy. Patients were categorized in DM+ (n = 13pts) and DM- (n = 13 pts), according to the presence of diabetes mellitus (DM) at FU. Results: Despite similar hemodynamics and HbA1c levels at BL, DM+ pts had higher HbA1c levels (46,00 ± 13,79 vs 38,33 ± 4,88; p &lt; 0,05) at FU. No differences were noted in BL GLUT1, GLUT4 and SGLT gene expression between both groups. In DM- pts SGLT1(0,081 ± 0,080 vs 0,188 ± 0,108; p = 0,0036) , GLUT4(0,076 ± 0,068 vs 0,137 ± 0,065; p = 0,0011 )and GLUT1(0,020 ± 0,021 vs 0,022 ± 0,009; p = 0,043) increased significantly at FU whereas no change was observed in DM+ pts. Conclusion: Similar to experimental data, differential endomyocardial regulation in SGLT1 and GLUT4 was noted between DM+ and DM-pts with a blunted upregulation of glucose transporters at 1 year in DM+ HTx pts. These observations are in line with experimental data and suggest that myocardial glucose uptake is differentially regulated in DM+ HTx pts.

Novel fluorinated derivative of curcumin negatively regulates thioredoxin-interacting protein expression in retinal pigment epithelial and macrophage cells

Thioredoxin-interacting protein (TXNIP) has multiple disease-associated functions including inducing oxidative stress by inhibiting the anti-oxidant and thiol reducing activity of thioredoxin (TRX), reducing cellular glucose transport, and is a component of the activated inflammasome complex. Increased expression of TXNIP is encountered in diabetic conditions of high glucose. Curcumin and chemical derivatives have multiple therapeutic properties as anti-inflammatories, anti-oxidants, amyloid aggregation inhibitors and modulate a number of cellular signaling pathways. Using a fluorinated-derivative of curcumin (designated Shiga-Y6), we showed significant inhibition of TXNIP mRNA and protein expression, and induction of TRX mRNA and protein in ARPE-19 retinal pigment epithelial cells and THP-1-derived macrophages, while the non-fluorinated structural equivalent (Shiga-Y52) and native curcumin did not show these same effects. Shiga-Y6 was effective in reducing high glucose, endoplasmic reticulum stress-induced TXNIP in ARPE-19 cells, and reducing lipopolysaccharide and endoplasmic stress-induced proinflammatory gene expression in THP-1 macrophages. Moreover, TXNIP-knockdown experiments showed that the anti-inflammatory effect of Shiga-Y6 in LPS-stimulated THP-1 macrophages was TXNIP-independent.

ACE overexpression in myeloid cells increases oxidative metabolism and cellular ATP

ACE overexpression in myeloid cells increases oxidative metabolism and cellular ATP

Single Cell Glucose Uptake Assays: A Cautionary Tale.

Assays to monitor the metabolic state or nutrient uptake capacity of immune cells at a single cell level are increasingly in demand. One assay, used by many immunologists, employs 2-(N-(7-Nitrobenz-2-oxa-1,3-diazol-4-yl)Amino)-2-Deoxyglucose (2-NBDG), a fluorescent analogue of 2-deoxyglucose (2DG), as a substrate for glucose transporters. This molecule has been validated as a substrate for the glucose transporter Glut2 (Slc2a2) in mammalian cells but 2-NDBG selectivity for the glucose transporters expressed by T cells, Glut1 (Slc2a1) and Glut3 (Slc2a3), has never been explored. Nor has the possibility that 2-NBDG might bind to T cells that do not express glucose transporters been assessed. In this technical commentary we interrogate the specificity of 2-NBBG labelling as a readout for glucose transport in T lymphocytes. We compare flow cytometric 2-NBDG staining against well validated radiolabelled glucose transport assays in murine T cells. Our data show there can be a large discordance between glucose transport capacity and 2-NBDG labelling in T cells. We also find that 2-NBDG uptake into murine T cells is not inhibited by competitive substrates or facilitative glucose transporter inhibitors, nor can 2-NBDG competitively block glucose uptake in T cells. Collectively, these data argue that 2-NBDG uptake alone is not a reliable tool for the assessment of cellular glucose transport capacity.

Fluoxetine induces glucose uptake and modifies glucose transporter palmitoylation in human peripheral blood mononuclear cells

ABSTRACTIntroduction: In line with the monoamine hypothesis of major depressive disorder (MDD), the clinical efficacy of the selective serotonin reuptake inhibitor fluoxetine has classically been ascribed to central serotonin enhancing properties. Current research described disturbances in brain energy metabolism in MDD. Additionally, fluoxetine showed beneficial effects in neuropsychiatric disorders associated with central energy imbalance.Areas covered: The effect of in vitro fluoxetine exposure on cellular glucose uptake and cerebral glucose transporter function was assessed in human peripheral blood mononuclear cells (PBMC) and murine neuroblastoma N2a cells. Fluoxetine augmented glucose uptake, measured by utilizing the radionuclide-labled glucose analog [18]F-fluorodeoxyglucose, in PBMC without affecting glucose transporter protein content. Analysis of protein palmitoylation using the acyl-biotinyl exchange method revealed GLUT3 to be palmitoylated in PBMC and N2a cells, while palmitoylation of GLUT1 was detected only in N2a cells. Treatment with fluoxetine significantly increased palmitoylation of GLUT3 in PBMC and strongly induced palmitoylation of GLUT1 in PBMC and N2a cells.Expert opinion: Our findings suggest a novel mechanism exerted by fluoxetine targeting glucose metabolism by regulating glucose transporter palmitoylation. Thus, fluoxetine might evoke its therapeutic effects in neuropsychiatric diseases characterized by disturbances in central energy metabolism at least partly by improving cerebral glucose uptake.

Circulating blood cellular glucose transporters – Surrogate biomarkers for neonatal hypoxic-ischemic encephalopathy assessed by novel scoring systems

ObjectiveWe examined Red Blood Cell (RBC) Glucose Transporter isoform 1 (GLUT1) and White Blood Cell (WBC) Glucose Transporter isoform 3 (GLUT3) protein concentrations to assess their potential as surrogate biomarkers for the presence of hypoxic-ischemic encephalopathy (HIE) and response to therapeutic hypothermia (TH), with respect to the neurodevelopmental prognosis. Study designA prospective feasibility study of 10 infants with HIE and 8 age-matched control subjects was undertaken. Following parental consent, blood samples were obtained at baseline before institution of TH (<6 h of life), during TH, at rewarming and post-TH in the HIE group with a baseline sample from the control group. GLUT1 and GLUT3 were measured by Enzyme-linked immunosorbent assay (ELISA) with brain biomarkers, Neuron-Specific Enolase (NSE) and Glial Fibrillary Acidic Protein (GFAP). Novel “HIE-high risk” and “Neurological” scores were developed to help identify HIE and to assess severity and prognosis, respectively. ResultsRBC GLUT1 concentrations were increased at the baseline pre-TH time point in HIE versus control subjects (p = .006), normalizing after TH (p = .05). An association between GLUT1 and NSE concentrations (which was reflective of the HIE-high risk and the Neuro-scores) in controls and HIE pre-TH was seen (R2 = 0.36, p = .008), with GLUT1 demonstrating 90% sensitivity and 88% specificity for presence of HIE identified by Sarnat Staging. WBC GLUT3 concentrations were low and no different in HIE versus control, and GFAP concentrations trended higher during re-warming (p = .11) and post-TH (p = .16). We demonstrated a significant difference between HIE and controls for both the “HIE-high risk” and the “Neurological” Scores. The latter score revealing the severity of clinical neurological illness correlated with the corresponding RBC GLUT1 (R2 value = 0.39; p = .006). ConclusionCirculating RBC GLUT1 concentrations with NSE demonstrate a significant potential in reflecting the severity of HIE pre-TH and gauging effectiveness of TH. In contrast, the low neonatal WBC GLUT3 concentrations make discerning differences between degrees of HIE as well as assessing effectiveness of TH difficult. The HIE-high risk and Neurological scores may extend the “Sarnat staging” towards assessing severity and neuro-developmental prognosis of HIE.

MON-107 Endothelium Derived Factors Influence Differentiation of Fat Derived Stromal Cells

By 2030, the prevalence of diabetes will rise by 54% and will become a global epidemic. Aerobic exercise is known to show positive effects on cardiovascular health in diabetes and pre-diabetes subjects. However, the effect of exercise on vascular health was being studied using plasma biochemistry rather than cellular data. We investigated if endothelial conditioned media can affect MSC differentiation in adipogenic environment. We also examined the effect of aerobic exercise on the subject’s fat derived MSCs to study stromal cell differentiation. Methods: In vitro, commercially obtained human fat-derived stromal cells were exposed to adipogenic media and endothelial conditioned media (obtained from mature endothelial cells, HUVECs, 40 fold concentrated) was added. MSC differentiation was monitored by RT-PCR. For the in-vivo study, five prediabetic subjects, BMI > 25 were enrolled in a 12-week exercise program. Parameters were assessed pre and post exercise. Stromal cells were obtained from subcutaneous abdominal fat and cultured for 2-3 weeks. Stromal cells were then analyzed for gene expression. Results: We noted a reduced expression of markers for adipogenic differentiation such as PL1N, FABP4, CEBPA and PPARG (24.6, 13.3, 9.8, 4.2 fold, p= 0.00001, 0.02, 0.00001, 0.0001 respectively). We also observed increased expression of bone formation markers RUNX2 and BMP2 (1.5, 1.3 fold, p=0.01, 0.01 respectively) which were increased significantly. We also noted upregulation of VEGF and KDR (1.6 and 2.3 fold, respectively). When we analyzed mRNA expression of patient’s fat-derived stromal cells, we noticed, an upregulation of glucose transporter GLUT1, GLUT4 (3.6, 1.14 fold). Gene expression of most of the antioxidants such as SOD2, SOD3, GPX1, GPX3 and CAT (1.5, 1.7. 1.16, 1.6 and 1.6 fold respectively) increased post exercise with a statistically significant upregulation of SOD1, a cytosolic antioxidant (p= 0.04, 1.8 fold). Differentiation towards fat, bone, muscle and cartilage, using mRNA expression analysis, showed a trend of upregulation of bone formation marker osteocalcin (BGLAP), BMP6, SMAD3 and TGF-ᵝ (1.3, 2.6, 2, 3.1 fold respectively) post exercise. Concomitantly, serum values of osteocalcin increased significantly, post-exercise. Biophysical and biochemical parameters demonstrated that exercise increased METs significantly (p=0.04, 12%) while reduced body weight, systolic, diastolic blood pressure, HbA1c, cholesterol by 4.2%,9%, 9%, 10%, 9.8 % respectively (p=0.04, 0.04, 0.05, 0.001, 0.0003 respectively) Conclusion: Both in-vivo and in-vitro data showed that exercise augments cellular glucose transporters, anti-oxidants and reduce MSC inflammation. Addition of endothelium-derived factors and exercise both appear to augment bone formation markers indicating a cross-talk between endothelium, fat differentiation, and bone formation, post-exercise.

Effects of Magnesium Deficiency on Mechanisms of Insulin Resistance in Type 2 Diabetes: Focusing on the Processes of Insulin Secretion and Signaling.

Magnesium (Mg2+) is an essential mineral for human health and plays an important role in the regulation of glucose homeostasis and insulin actions. Despite the widespread clinical evidences for the association of Mg2+ deficiency (MgD) and type 2 diabetes mellitus (T2D), molecular mechanisms by which Mg2+ contributes to insulin resistance (IR) are still under discussion. Mg2+ regulates electrical activity and insulin secretion in pancreatic beta-cells. Intracellular Mg2+ concentrations are critical for the phosphorylation of the insulin receptor and other downstream signal kinases of the target cells. Low Mg2+ levels result in a defective tyrosine kinase activity, post-receptor impairment in insulin action, altered cellular glucose transport, and decreased cellular glucose utilization, which promotes peripheral IR in T2D. MgD triggers chronic systemic inflammation that also potentiates IR. People with T2D may end up in a vicious circle in which MgD increases IR and IR causes MgD, that requires periodic monitoring of serum Mg2+ levels.

Higher lactate and purine metabolite levels in erythrocyte-rich fresh venous thrombus: Potential markers for early deep vein thrombosis

BackgroundThrombolytic therapy is effective in fresh deep vein thrombosis (DVT) although the benefit may fall below the risk of bleeding in non-fresh thrombosis. Markers reflecting fresh DVT have not been established. The present study aims to identify metabolites reflecting fresh venous thrombus and their role in thrombus formation. MethodsMetabolites of rabbit venous blood and jugular venous thrombus 4 h after thrombus induction were analysed using electrophoresis-time of flight mass spectrometry. The effects of the altered metabolites on blood coagulation and platelet aggregation were assessed by using rotation thromboelastometry and platelet aggregometer. Cellular contents and glucose transporter (Glut)-1 expression in aspirated human DVT samples were pathologically analysed. ResultsMetabolome analysis identified 226 metabolites (133 cationic and 93 anionic metabolites). Largely altered 18 metabolites (thrombus/blood ratio: >5 or <0.5) included glycolytic metabolites, redox-related metabolites, purine nucleotides and tryptophan metabolites. Among the metabolites with >5-fold increase, lactic acid was most abundant and guanine modestly enhanced whole blood clotting with thromboelastometry. Lactic acid and adenosine monophosphate inhibited collagen-induced platelet aggregation. Human DVTs were rich in erythrocytes expressing Glut-1. The erythrocyte content and Glut-1 expression were negatively correlated with the time after onset of DVT. ConclusionsGlycolysis-, purine-, and redox-related metabolites may reflect fresh erythrocyte-rich venous thrombus, and altered metabolites may affect venous thrombus formation. An increased level of lactate may reflect active glycolysis of thrombus cellular components, predominantly erythrocytes.

Exercise Increases Glucose Transporter-4 Levels on Peripheral Blood Mononuclear Cells.

Glucose transporter 4 (GLUT4) plays a key role in the pathophysiology of type 2 diabetes. Glucose transporter 4 is upregulated in response to exercise, enhancing cellular glucose transport in skeletal muscle tissue. This mechanism appears to remain intact in individuals with insulin resistance. Details of the mechanism are poorly understood and are challenging to study due to the invasive nature of muscle biopsy. Peripheral blood mononuclear cells (PBMC) have documented insulin-sensitive GLUT4 activity and may serve as a proxy tissue for studying skeletal muscle GLUT4. The purpose of this study was to investigate whether GLUT4 in PBMC is affected by conditioning. We recruited 16 student athletes from the cross-country running and skiing teams and fifteen sedentary students matched for age and sex from the University of Alaska Fairbanks. Peripheral blood mononuclear cells were collected with mononuclear cell separation tubes. The GLUT4 concentrations were measured using a commercially available enzyme linked immunosorbent assay. Additionally, correlations between PBMC GLUT4 and common indicators of insulin resistance were examined. Results indicate significantly higher PBMC GLUT4 levels in conditioned athletes than in their sedentary counterparts, similar to what has been documented in myocytes. Females were observed to have higher PBMC GLUT4 levels than males. Correlations were not detected between PBMC GLUT4 and hemoglobin A1c, glucose, insulin, homeostatic model assessment of insulin resistance, body mass index, or body fat. This study provides evidence to support exploration of PBMC as a proxy tissue for studying GLUT4 response to exercise or other noninsulin factors.

Abstract P031: Effect of Exercise on Function and Differentiation of Adipose Tissue Derived Mesenchymal Stromal Cells (MSCs)

Approximately 422 million people have diabetes worldwide (2014) and it is predicted that diabetes will rise by nearly 54% by 2030. Aerobic exercise is known to show positive effect on health of diabetic and pre diabetic patients. The effect of exercise has been studied extensively using plasma biochemistry but cellular data is scares. Previously, we have shown endothelial progenitor cells (EPCs) can act as a strong cellular biomarker of endothelial function following aerobic exercise as an intervention. In this study, we are examining the effect of aerobic exercise on adipocyte derived MSCs to study stromal cell differentiation and as a cellular surrogate of fat metabolism. Methods: Overweight and obese subjects (n=5) were enrolled in a 12 week exercise intervention study. The biweekly exercise sessions were supervised by a trained exercise physiologist and consisted of a 1 hour sessions that included warm-up and cool-down and 30 min of combined aerobic and resistance training at an exercise intensity of 50-80% of heart rate reserve. Physical and biochemical parameters were tested pre and post exercise. Subcutaneous abdominal fat biopsies were obtained and fat derived stromal cells were cultured in vitro for 2-3 weeks. MSCs were analyzed for mRNA gene expression (qRT-PCR) and cellular oxygen consumption rate (OCR), pre and post 12 week exercise. Results: With exercise, A1C reduced significantly. An increase of METs was also noticed post exercise. Both basal and maximal respiration increased significantly post exercise when compared with commercially obtained MSCs. Simultaneously, mitochondrial genes COX4 and ATP5B (p= 0.01, 1.4 fold, 0.02, 1.5 fold respectively), Glucose transporter, GLUT1 (p=0.04, 1.8 fold), antioxidants GPX3 and CAT (p= 0.01, 3.2 fold and p=0.04, 1.5 fold respectively) upregulated whereas pro-inflammatory cyclo-oxygenase-2 (p=0.04, 2.5 fold) gene reduced significantly, post exercise. Regarding differentiation potential of multipotent MSCs, post exercise, we noted enhanced expression of bone markers such Alkaline Phosphatase (p= 0.03, 2.7 fold) BGLAP and RUNX2 (1.3 and 1.2 fold) and also for collagen marker COL2 (2.4 fold) expression. For adipogenic differentiation potential PPARG mRNA expression was reduced. Interestingly, serum value of osteocalcin increased significantly from 15.0 (5.5) to 16.3(6.1) ng/ml (9% increase, p=0.03) with 1% increase in bone alkaline phosphatase level, post exercise. Conclusion: We conclude that exercise augments cellular glucose transporters (GLUT1), anti-oxidants and reduce MSC inflammation and up-regulates mitochondrial function and gene expression profile of MSCs. Increased serum value of osteocalcin complement increased gene expression of bone formation markers indicating a cross talk between fat derived MSCs and bone formation, post exercise.

Inhibition of Intestinal Cellular Glucose Uptake by Phenolics Extracted from Whole Wheat Grown at Different Locations.

Whole grain consumption is associated with reduced risk of type 2 diabetes, and the underlying mechanism might be related to the actions of polyphenols. Dietary polyphenols contribute to low glycemic indices through inhibition of intestinal glucose transport proteins. This study has two objectives: (1) to evaluate how the contents of phenolic acids in wheat vary by genetic background and growth condition and (2) to evaluate how these changes translate into physiologic relevance by investigating cellular glucose transporter inhibitions. Phenolic acids were extracted from wheat varieties grown at different locations over two crop years. The degree of inhibition of glucose uptake into human Caco-2E cells was determined. Free and bound phenolic acid extracts of all wheat genotypes inhibited glucose uptake. Degree of glucose uptake inhibitions positively correlated with the contents of free and bound phenolic acids, and the correlation coefficients were R2=0.91 and R2=0.89, respectively. Genotype and environment influenced the content of free and bound phenolic acids which linearly translated to the degree of glucose uptake inhibition in a model of intestinal absorption (P < 0.05). Results of this work mechanistically support the hypothesis that dietary phenols positively influence the glycemic index and therefore the health properties of whole grain consumption.

The flavanone homoeriodictyol increases SGLT-1-mediated glucose uptake but decreases serotonin release in differentiated Caco-2 cells.

Flavanoids and related polyphenols, among them hesperitin, have been shown to modulate cellular glucose transport by targeting SGLT-1 and GLUT-2 transport proteins. We aimed to investigate whether homoeriodictyol, which is structurally related to hesperitin, affects glucose uptake in differentiated Caco-2 cells as a model for the intestinal barrier. The results revealed that, in contrast to other polyphenols, the flavanon homoeriodictyol promotes glucose uptake by 29.0 ± 3.83% at a concentration of 100 μM. The glucose uptake stimulating effect was sensitive to phloridzin, but not to phloretin, indicating an involvement of the sodium-coupled glucose transporter SGLT-1, but not of sodium-independent glucose transporters (GLUT). In addition, in contrast to the increased extracellular serotonin levels by stimulation with 500 mM D-(+)-glucose, treatment with 100 μM homoeriodictyol decreased serotonin release by –48.8 ± 7.57% in Caco-2 cells via a phloridzin-sensitive signaling pathway. Extracellular serotonin levels were also reduced by –57.1 ± 5.43% after application of 0.01 μM homoeriodictyol to human neural SH-SY5Y cells. In conclusion, we demonstrate that homoeriodictyol affects both the glucose metabolism and the serotonin system in Caco-2 cells via a SGLT-1-meditated pathway. Furthermore, the results presented here support the usage of Caco-2 cells as a model for peripheral serotonin release. Further investigations may address the value of homoeriodictyol in the treatment of anorexia and malnutrition through the targeting of SGLT-1.

Identification of TDP-43 as an oncogene in melanoma and its function during melanoma pathogenesis

ABSTRACTBackground: Although recent studies have revealed TAR (trans-activating response region) DNA binding protein (TDP-43) as a potential therapeutic target for cancers, its role and clinical association with melanoma have not been explored. Objective: To identify the role and function of TDP-43 during melanoma pathogenesis. Methods: Firstly, the relationship between TDP-43 expression and patient survival was explored. Then TDP-43 expression level in melanoma tissue and different melanoma cell lines was measured. After silencing TDP-43 expression in melanoma cells, the impacts of TDP-43 on cellular proliferation, metastasis, glucose uptake, and glucose transporters levels were studied. In the end, effect of TDP-43 depletion on tumorigenicity of melanoma cells was tested in vivo. Results: Our results showed that TDP-43 was overexpressed in melanoma paraffin samples compared with that in nevi tissues. The high expression level of TDP-43 was associated with poor patient survival. By silencing TDP-43, we saw significant inhibition of cell proliferation and metastasis in A375 and WM451 cells. TDP-43 knockdown could suppress glucose transporter type-4 (GLUT4) expression and reduce glucose uptake. And downregulation of GLUT4 in melanoma cells induced inhibition of cell proliferation and metastasis. TDP-43 knockdown significantly slowed down tumor growth and decreased GLUT4 expression in vivo. Conclusion: TDP-43 is a novel oncogene in melanoma and regulates melanoma proliferation and metastasis potentially through modulation of glucose metabolism.

Bioactivities of fish protein hydrolysates from defatted salmon backbones

Bioactivities of bulk fish protein hydrolysates (FPH) from defatted salmon backbones obtained with eight different commercial enzymes and their combinations were tested. All FPH showed antioxidative activity in vitro. DPPH scavenging activity increased, while iron chelating ability decreased with increasing time of hydrolysis. All FPH showed ACE inhibiting effect which depended on type of enzyme and increased with time of hydrolysis. The highest effect was found for FPH produced with Trypsin. Bromelain+Papain hydrolysates reduced the uptake of radiolabelled glucose into CaCo-2 cells, a model of human enterocytes, indicating a potential antidiabetic effect of FPH. FPH obtained by Trypsin, Bromelain+Papain and Protamex showed the highest ACE inhibitory, cellular glucose transporter (GLUT/SGLT) inhibitory and in vitro antioxidative activities, respectively. Correlation was observed between the measured bioactivities, degree of hydrolysis and molecular weight profiles, supporting prolonged hydrolysis to obtain high bioactivities.