GLUT4 Gene Expression Research Articles

Relationship between metabolic and structural remodeling during DCM progression in human

Introduction: Whether switch of energy substrates in dilated cardiomyopathy (DCM) is adaptive or causally related to myocardial pathology is still controversial. Thus the aim of our study was a link between structural and metabolic remodeling during DCM progression to heart failure (HF). Population study and methods. Archival RV tissue samples forty-four patients analysed histopathologically and ultrastructurally were subdivided into three groups according to EF determined at the time of admission: group (I) EF 45-55% (n=14, age 23,23±11,75 years), (II) EF 30-44% (n=15, age 24,67±10,36 years), (III) EF <30% (n=15, age 48,66±13,8 years). RNA from ten frozen samples belonging to mentioned groups was isolated and expression levels of PPARα, FAT/CD36, GLUT-4, and CPT-1 investigated. Results: Analysis revealed that with decrease of EF from 45-55% to about 35% was related to increased tissue fibrosis (from 6,15±5,45% to 8,29±5,26%) and cardiomyocytes hypertrophy (from diameter of 17,55±8,07 μm to 18,24±4,62 μm) with accompanying slight reduction of contractile apparatus and increase of mitochondria number and glycogen abundance, and transition of desmin expression from normal pattern to aggregates are characteristic features. Parallel, increase of PPARα and CPT-1, and GLUT-4 and decrease of FAT/CD36 gene expression was observed. While, in myocardial tissues of hearts with decreased EF to <30% was observed significant increase of fibrosis (14,23±12,4%), and not much progress in cardiomyocytes hypertrophy (cells diameter 18,75±4, 44 μm) but significant cell remodeling (related to significant loss of myofibrils, and glycogen, and mitochondria, and desmin cytoskeleton expression, and lipid droplets occurrence). These was accompanying by increased expression of genes - PPARα and FAT/CD36 and CPT-1 comparing to group II about 50% and 150% and 20% respectively, and lowered expression of GLUT4 gene. Conclusions: Obtained data reveled that switch of energy substrates precede cardiomyocytes structural disturbances in DCM. Furthermore, in early disease state glucose metabolism is activated probably to compensate decreased fatty acid transport, particularly that reserve of intracellular glucose is available. While, increase of PPARα and FAT/CD36 genes in later disease stage together with decrease of mitochondria number may lead to toxic lipids storage and cell injury. These data suggest the energetic metabolism as therapeutic purpose to prevent cardiac remodelling in DCM.

MiRNA-93 Inhibits GLUT4 and Is Overexpressed in Adipose Tissue of Polycystic Ovary Syndrome Patients and Women With Insulin Resistance

Approximately 70% of women with polycystic ovary syndrome (PCOS) have intrinsic insulin resistance (IR) above and beyond that associated with body mass, including dysfunctional glucose metabolism in adipose tissue (AT). In AT, analysis of the IRS/PI3-K/AKT pathway signaling components identified only GLUT4 expression to be significantly lower in PCOS patients and in control subjects with IR. We examined the role of miRNAs, particularly in the regulation of GLUT4, the insulin-sensitive glucose transporter, in the AT of PCOS and matched control subjects. PCOS AT was determined to have a differentially expressed miRNA profile, including upregulated miR-93, -133, and -223. GLUT4 is a highly predicted target for miR-93, while miR-133 and miR-223 have been demonstrated to regulate GLUT4 expression in cardiomyocytes. Expression of miR-93 revealed a strong correlation between the homeostasis model assessment of IR in vivo values and GLUT4 and miR-93 but not miR-133 and -223 expression in human AT. Overexpression of miR-93 resulted in downregulation of GLUT4 gene expression in adipocytes through direct targeting of the GLUT4 3′UTR, while inhibition of miR-93 activity led to increased GLUT4 expression. These results point to a novel mechanism for regulating insulin-stimulated glucose uptake via miR-93 and demonstrate upregulated miR-93 expression in all PCOS, and in non-PCOS women with IR, possibly accounting for the IR of the syndrome. In contrast, miR-133 and miR-223 may have a different, although yet to be defined, role in the IR of PCOS.

Modulation of Skeletal Muscle Performance and SERCA by Exercise and Adiponectin Gene Therapy in Insulin-Resistant Rat

This study addresses the potential application of adiponectin gene therapy and exercise in protection against skeletal muscle dysfunction in type 2 diabetes mellitus (T2DM) while focusing on the role of sarco and endoplasmic reticulum Ca(+2) ATPase (SERCA) and Glut4. 50 rats were divided into five groups: control, T2DM, T2DM treated with either adiponectin gene or exercise or a combination of both. Serum glucose, insulin, HOMA index, triglycerides, and cholesterol were measured. Weight gain%, muscle contractile parameters {(peak twitch tension (Pt), peak tetanic tension (PTT), half relaxation time (HRT)}, and gene expression of SERCA, Glut4, and adiponectin were assessed in gastrocnemius muscle. Diabetic rats treated with either adiponectin gene or exercise showed significant reduction in all serum parameters and wt gain%. There was significant elevation in Pt and PTT with shortening in HRT. Furthermore, a significant increase in SERCA, Glut4, and adiponectin gene expression was noticed in both groups. Combination therapy caused marked gene expression of SERCA, GLUT4, and greater improvement in muscle contractility than either of the monotherapies. Skeletal muscle dysfunction in T2DM is mediated via impaired SERCA and Glut 4. Combination therapy offered best protection against muscle dysfunction and provides a novel promising strategy for a complete cure of muscle dysfunction in T2DM.

Metabolic regulation of osteoclast differentiation and function

The osteoclast is a giant cell that resorbs calcified matrix by secreting acids and collagenolytic enzymes. The molecular mechanisms underlying metabolic adaptation to the increased biomass and energetic demands of osteoclastic bone resorption remain elusive. Here we show that during osteoclastogenesis the expression of both glucose transporter 1 (Glut1) and glycolytic genes is increased, whereas the knockdown of hypoxia-inducible factor 1-alpha (Hif1α), as well as glucose deprivation, inhibits the bone-resorbing function of osteoclasts, along with a suppression of Glut1 and glycolytic gene expression. Furthermore, the expression of the glutamine transporter solute carrier family 1 (neutral amino acid transporter), member 5 (Slc1a5) and glutaminase 1 was increased early in differentiation, and a depletion of L-glutamine or pharmacological inhibition of the Slc1a5 transporter suppressed osteoclast differentiation and function. Inhibition of c-Myc function abrogated osteoclast differentiation and function, along with a suppression of Slc1a5 and glutaminase 1 gene expression. Genetic and pharmacological inhibition of mammalian target of rapamycin (mTOR), as well as the activation of adenosine monophosphate (AMP)-activated protein kinase (AMPK), inhibited osteoclastogenesis. Thus, the uptake of glucose and glutamine and utilization of the carbon sources derived from them, coordinated by HIF1α and c-Myc, are essential for osteoclast development and bone-resorbing activity through a balanced regulation of the nutrient and energy sensors, mTOR and AMPK.

Environmental toxin-linked nonalcoholic steatohepatitis and hepatic metabolic reprogramming in obese mice.

Obesity is associated with strong risks of development of chronic inflammatory liver disease and metabolic syndrome following a second hit. This study tests the hypothesis that free radical metabolism of low chronic exposure to bromodichloromethane (BDCM), a disinfection byproduct of drinking water, causes nonalcoholic steatohepatitis (NASH), mediated by cytochrome P450 isoform CYP2E1 and adipokine leptin. Using diet-induced obese mice (DIO), mice deficient in CYP2E1, and mice with spontaneous knockout of the leptin gene, we show that BDCM caused increased lipid peroxidation and increased tyrosine nitration in DIO mice, events dependent on reductive metabolism by CYP2E1. DIO mice, exposed to BDCM, exhibited increased hepatic leptin levels and higher levels of proinflammatory gene expression and Kupffer cell activation. Obese mice exposed to BDCM also showed profound hepatic necrosis, Mallory body formation, collagen deposition, and higher alpha smooth muscle actin expression, events that are hallmarks of NASH. The absence of CYP2E1 gene in mice that were fed with a high-fat diet did not show NASH symptoms and were also protected from hepatic metabolic alterations in Glut-1, Glut-4, phosphofructokinase and phosphoenolpyruvate carboxykinase gene expressions (involved in carbohydrate metabolism), and UCP-1, PGC-1α, SREBP-1c, and PPAR-γ genes (involved in hepatic fat metabolism). Mice lacking the leptin gene were significantly protected from both NASH and metabolic alterations following BDCM exposure, suggesting that higher levels of leptin induction by BDCM in the liver contribute to the development of NASH and metabolic alterations in obesity. These results provide novel insights into BDCM-induced NASH and hepatic metabolic reprogramming and show the regulation of obesity-linked susceptibility to NASH by environmental factors, CYP2E1, and leptin.

Metformin augments the levels of molecules that regulate the expression of the insulin-dependent glucose transporter GLUT4 in the endometria of hyperinsulinemic PCOS patients

Does treatment with the insulin sensitizer metformin modify the levels and activation of proteins related to the expression of the insulin-dependent glucose transporter (GLUT4), such as adenosine monophosphate-activated protein kinase (AMPK) and myocyte enhancer factor 2A (MEF2A), in endometria from hyperinsulinemic hyperandrogenemic polycystic ovary syndrome (PCOS h-Ins) patients? In PCOS h-Ins patients, metformin increases endometrial levels of GLUT4 mRNA and protein levels by normalizing the quantity and activation of molecules that regulate GLUT4 expression to healthy values. These changes could improve endometrial metabolic function. PCOS is an endocrine-metabolic disorders closely associated with insulin resistance. In particular, the insulin signaling pathway is impaired in endometria from these patients and the concentration of GLUT4, as well as the molecules involved in its translocation to the cell surface, is decreased. However, there are limited data about the mechanisms that regulate the GLUT4 expression in the endometria and the effect of metformin on them. This is a case-control study in the setting of a research unit, approved by the Ethical Committees of our institution. The groups whose endometria were studied were PCOS h-Ins (n = 8); PCOS patients with hyperandrogenemia hyperinsulinemia taking only metformin for at least 3 months (PCOS-MTF, n = 8) and healthy fertile women at the time of hysterectomy because of benign pathology as controls (CE, n = 8). Steroids and sex hormone-binding globulin were measured and glucose and insulin levels were evaluated during an oral glucose tolerance test. Protein levels for αAMPK (catalytic subunit of AMPK), phosphorylated (p)-AMPKαThr(172) (activating phosphorylation site), MEF2A, p-MEF2AThr312 (activating phosphorylation site) and GLUT4 were assessed by western blot and immunohistochemistry. In addition, GLUT4 gene expression was evaluated by RT-PCR. We found significantly lower levels of MEF2A and p-MEF2AThr312 in PCOS h-Ins compared with CE endometria (P < 0.05). Also, we detected lower levels of p-AMPKαThr(172) in PCOS h-Ins endometria compared with the PCOS-MTF group (P < 0.05). The ratios of phospho-AMPK/total AMPK and phospho-MEF2A/total MEF2A were significantly increased in the PCOS-MTF compared with the PCOS h-Ins group (P < 0.05). The RT-PCR experiments showed lower levels of GLUT4 mRNA transcripts in PCOS h-Ins compared with PCOS-MTF-treated group (P < 0.05), the protein levels of GLUT4 were decreased in a similar way. The limited number of patients included in this study who presented large clinical variability. Therefore, it would be necessary to recruit a greater number of patients to minimize our data dispersion in order to prove the clinical benefits of metformin described by others. Since the insulin sensitizer metformin increases the expression of the GLUT4, it may improve endometrial physiology in PCOS patients and, therefore, promote better reproductive outcomes. These results suggest that in PCOS patients, metformin may act directly at the endometrial level and decrease insulin resistance condition by increasing the expression of GLUT4 and, in this way, indirectly restore endometrial function. This work was supported by Fondo Nacional de Desarrollo Científico y Tecnológico (grant number 1095127 to M.V.). None of the authors has any conflict of interest to declare.

Ginsenoside Re reduces insulin resistance through activation of PPAR-γ pathway and inhibition of TNF-α production

Ethnopharmacological relevancePanax ginseng is a well-known traditional Chinese medicine and has been used for treatment of various diseases for more than four thousand years in Asia. Ginseng saponins or ginsenosides, the active constituents are reported to possess antidiabetic activity, but their antihyperglycemic mechanisms are not fully elucidated. In the present study, the mechanisms of action of ginsenoside Re were investigated in vitro models. Materials and methods3T3-L1 cells were chosen as the model to investigate the molecular mechanisms of action of ginsenoside Re. Influence of ginsenoside Re on the adipogenesis was examined by determining TG levels in 3T3-L1 adipocytes by the method of TG oxidation enzyme. Glucose uptake in 3T3-L1 cells stimulated by insulin in the absence or presence of ginsenoside Re were quantified by measuring 3H-2-deoxy-d-glucose levels. Cytokine proteins released into the medium including adiponectin and TNF-α were tested using respective ELISA kits. In addition, real time RT-PCR was conducted to investigate the expression changes of PPAR-γ and its responsive genes, ap2, adiponectin, IRS-1, GLUT4 and TNF-α. And western blot analysis was performed to determine the translocation of GLUT4. Finally, effects of ginsenoside Re on NO production in 3T3-L1 adipocytes and in macrophages were investigated through measurement of nitrite concentration by Griess reagent. ResultsGinsenoside Re induced adipogenesis of 3T3-L1 adipocytes by accumulating TG, increased glucose uptake and up-regulated PPAR-γ2, IRS-1, ap2 and adiponectin genes expressions. Meanwhile, Re also increased production and release of adiponectin. Although having no effects on GLUT4 gene expression, Re facilitated GLUT4 protein translocation to the membranes. In addition, Re inhibited the expression and release of TNF-α. Finally, Re did not show inhibitory effects on NO production both in 3T3-L1 cells stimulated by LPS, TNF-α and IFN-γ and in LPS-stimulated mouse peritoneal macrophages. ConclusionsGinsenoside Re exhibited the action of reducing insulin resistance through activation of PPAR-γ pathway by directly increasing the expressions of PPAR-γ2 and its responsive genes, adiponectin, IRS-1, ap2, inhibiting TNF-α production and facilitating the translocation of GLUT4 to promote glucose uptake and disposal in 3T3-L1 adipocytes.

Curcumin restores diabetes induced neurochemical changes in the brain stem of Wistar rats

Diabetes mellitus, when poorly controlled, leads to debilitating central nervous system (CNS) complications including cognitive deficits, somatosensory and motor dysfunction. The present study investigated curcumin′s potential in modulating diabetes induced neurochemical changes in brainstem. Expression analysis of cholinergic, insulin receptor and GLUT-3 in the brainstem of streptozotocin (STZ) induced diabetic rats were studied. Radioreceptor binding assays, gene expression studies and immunohistochemical analysis were done in the brainstem of male Wistar rats. Our result showed that Bmax of total muscarinic and muscarinic M3 receptors were increased and muscarinic M1 receptor was decreased in diabetic rats compared to control. mRNA level of muscarinic M3, α7-nicotinic acetylcholine, insulin receptors, acetylcholine esterase, choline acetyltransferase and GLUT-3 significantly increased and M1 receptor decreased in the brainstem of diabetic rats. Curcumin and insulin treatment restored the alterations and maintained all parameters to near control. The results show that diabetes is associated with significant reduction in brainstem function coupled with altered cholinergic, insulin receptor and GLUT-3 gene expression. The present study indicates beneficial effect of curcumin in diabetic rats by regulating the cholinergic, insulin receptor and GLUT-3 in the brainstem similar to the responses obtained with insulin therapy.

Sterculic Oil, a natural inhibitor of SCD1, improves the metabolic state of obese OLETF rats

Abnormal lipid metabolism and excess accumulation of lipid in non-adipose tissues are defining characteristics of obesity and its comorbidities. Expression and/or activity of stearoyl-CoA desaturase-1 (SCD1), a major regulator of lipid metabolism, is increased with obesity and the reduction/ablation of this enzyme is associated with an improved metabolic profile. Sterculic oil (SO), obtained from the seeds of the Sterculia feotida tree, contains a high concentration of cyclopropenoic fatty acids which are known inhibitors of SCD1. The purpose of this study was to determine the effects of SO supplementation on the development of obesity and insulin resistance in hyperphagic, obese Otsuka Long-Evans Tokushima Fatty (OLETF) rats. Rats received either an AIN-93G diet (control) or an AIN-93G diet containing 0.5% SO for 10 weeks. SO did not alter body weight or body composition. Importantly, the desaturase indices, a proxy for the activity of SCD1, were reduced in the liver and adipose tissue of SO supplemented animals. This reduction in SCD1 activity was associated with a reduction in fasting blood glucose concentrations and improved glucose tolerance. In addition, SO reduced intra-abdominal fat mass and adipocyte size and resulted in a ∼3-fold increase in GLUT1 gene expression in intra-abdominal fat. Liver triglyceride content and lipogenic gene expression were reduced by SO. Consistent with an improved metabolic phenotype, SO also improved plasma cholesterol, LDL-cholesterol, and triglyceride concentrations. Overall, our data demonstrate an improved metabolic phenotype with SO supplementation and suggest further studies are required to better understand the therapeutic potential of SO.

Low intrinsic exercise capacity in rats predisposes to age-dependent cardiac remodeling independent of macrovascular function

Rats selectively bred for low (LCR) or high (HCR) intrinsic running capacity simultaneously present with contrasting risk factors for cardiovascular and metabolic disease. However, the impact of these phenotypes on left ventricular (LV) morphology and microvascular function, and their progression with aging, remains unresolved. We tested the hypothesis that the LCR phenotype induces progressive age-dependent LV remodeling and impairments in microvascular function, glucose utilization, and β-adrenergic responsiveness, compared with HCR. Hearts and vessels isolated from female LCR (n = 22) or HCR (n = 26) were studied at 12 and 35 wk. Nonselected N:NIH founder rats (11 wk) were also investigated (n = 12). LCR had impaired glucose tolerance and elevated plasma insulin (but not glucose) and body-mass at 12 wk compared with HCR, with early LV remodeling. By 35 wk, LV prohypertrophic and glucose transporter GLUT4 gene expression were up- and downregulated, respectively. No differences in LV β-adrenoceptor expression or cAMP content between phenotypes were observed. Macrovascular endothelial function was predominantly nitric oxide (NO)-mediated in both phenotypes and remained intact in LCR for both age-groups. In contrast, mesenteric arteries microvascular endothelial function, which was impaired in LCR rats regardless of age. At 35 wk, endothelial-derived hyperpolarizing factor-mediated relaxation was impaired whereas the NO contribution to relaxation is intact. Furthermore, there was reduced β2-adrenoceptor responsiveness in both aorta and mesenteric LCR arteries. In conclusion, diminished intrinsic exercise capacity impairs systemic glucose tolerance and is accompanied by progressive development of LV remodeling. Impaired microvascular perfusion is a likely contributing factor to the cardiac phenotype.

Hyperglycemia Slows Embryonic Growth and Suppresses Cell Cycle via Cyclin D1 and p21

In pregnant women, the diabetic condition results in a three- to fivefold increased risk for fetal cardiac malformations as a result of elevated glucose concentrations and the resultant osmotic stress in the developing embryo and fetus. Heart development before septation in the chick embryo was studied under two hyperglycemic conditions. Pulsed hyperglycemia induced by daily administration of glucose during 3 days of development caused daily spikes in plasma glucose concentration. In a second model, sustained hyperglycemia was induced with a single injection of glucose into the yolk on day 0. The sustained model raised the average plasma glucose concentration from 70 mg/dL to 180 mg/dL and led to decreased gene expression of glucose transporter GLUT1. Both models of hyperglycemia reduced embryo size, increased mortality, and delayed development. Within the heart outflow tract, reduced proliferation of myocardial and endocardial cells resulted from the sustained hyperglycemia and hyperosmolarity. The cell cycle inhibitor p21 was significantly increased, whereas cyclin D1, a cell cycle promoter, decreased in sustained hyperglycemia compared with controls. The evidence suggests that hyperglycemia-induced developmental delays are associated with slowed cell cycle progression, leading to reduced cellular proliferation. The suppression of critical developmental steps may underlie the cardiac defects observed during late gestation under hyperglycemic conditions.

Glucan-rich polysaccharides from Pleurotus sajor-caju (Fr.) Singer prevents glucose intolerance, insulin resistance and inflammation in C57BL/6J mice fed a high-fat diet

BackgroundPleurotus sajor-caju (P. sajor-caju) has been extremely useful in the prevention of diabetes mellitus due to its low fat and high soluble fiber content for thousands of years. Insulin resistance is a key component in the development of diabetes mellitus which is caused by inflammation. In this study, we aimed to investigate the in vivo efficacy of glucan-rich polysaccharide of P. sajor-caju (GE) against diabetes mellitus and inflammation in C57BL/6J mice fed a high-fat diet.MethodsDiabetes was induced in C57BL/6J mice by feeding a high-fat diet. The mice were randomly assigned to 7 groups (n=6 per group). The control groups in this study were ND (for normal diet) and HFD (for high-fat diet). The treated groups were ND240 (for normal diet) (240 mg/kg b.w) and HFD60, HFD120 and HFD240 (for high-fat), where the mice were administrated with three dosages of GE (60, 120, 240 mg GE/kg b.w respectively). Metformin (2 mg/kg b.w) served as positive control. The glucose tolerance test, glucose and insulin levels were measured at the end of 16 weeks. Expressions of genes for inflammatory markers, GLUT-4 and adiponectin in the adipose tissue of the mice were assessed. One-way ANOVA and Duncan’s multiple range tests (DMRT) were used to determine the significant differences between groups.ResultsGE treated groups improved the glucose tolerance, attenuated hyperglycemia and hyperinsulinemia in the mice by up-regulating the adiponectin and GLUT-4 gene expressions. The mice in GE treated groups did not develop insulin resistance. GE also down-regulated the expression of inflammatory markers (IL-6, TNF-α, SAA2, CRP and MCP-1) via attenuation of nuclear transcription factors (NF-κB).ConclusionGlucan-rich polysaccharide of P. sajor-caju can serve as a potential agent for prevention of glucose intolerance, insulin resistance and inflammation.

Recombinant Acylation Stimulating Protein Administration to C3−/− Mice Increases Insulin Resistance via Adipocyte Inflammatory Mechanisms

BackgroundComplement 3 (C3), a key component of the innate immune system, is involved in early inflammatory responses. Acylation stimulating protein (ASP; aka C3adesArg), a C3 cleavage product, is produced in adipose tissue and stimulates lipid storage. We hypothesized that, depending on the diet, chronic ASP administration in C3−/− mice would affect lipid metabolism and insulin sensitivity via an adaptive adipose tissue inflammatory response.Methodology/Principal FindingsC3−/− mice on normal low fat diet (ND) or high fat diet (HFD) were chronically administered recombinant ASP (rASP) for 25 days via an osmotic mini-pump. While there was no effect on food intake, there was a decrease in activity, with a relative increase in adipose tissue weight on ND, and a shift in adipocyte size distribution. While rASP administration to C3−/− mice on a ND increased insulin sensitivity, on a HFD, rASP administration had the opposite effect. Specifically, rASP administration in C3−/− HFD mice resulted in decreased gene expression of IRS1, GLUT4, SREBF1 and NFκB in muscle, and decreased C5L2 but increased JNK, CD36, CD11c, CCR2 and NFκB gene expression in adipose tissue as well as increased secretion of proinflammatory cytokines (Rantes, KC, MCP-1, IL-6 and G-CSF). In adipose tissue, although IRS1 and GLUT4 mRNA were unchanged, insulin response was reduced.ConclusionThe effects of chronic rASP administration are tissue and diet specific, rASP administration enhances the HFD induced inflammatory response leading to an insulin-resistant state. These results suggest that, in humans, the increased plasma ASP associated with obesity and cardiovascular disease could be an additional factor directly contributing to development of metabolic syndrome, insulin resistance and diabetes.

Comparison of the Effects of Glibenclamide on Metabolic Parameters, GLUT1 Expression, and Liver Injury in Rats With Severe and Mild Streptozotocin-Induced Diabetes Mellitus

Glucose transport via GLUT1 protein could be one of additional mechanisms of the antidiabetic action of sulfonylureas. Here, the GLUT1 gene and the protein expression was studied in rats in the course of severe and mild streptozotocin-induced diabetes mellitus and under glibenclamide treatment. Severe and mild diabetes mellitus was induced using different streptozotocin doses and standard or high fat chow. Rats were treated with glibenclamide (2 mg/kg daily, per os for 6 weeks). The therapeutic effect of glibenclamide was monitored by measuring several metabolic parameters. The GLUT1 mRNA and the protein expression in the kidneys, heart, and liver was studied by means of real-time RT-PCR and immunohistochemistry. The glibenclamide treatment decreased the blood glucose concentration and increased the insulin level in both models of severe and mild diabetes mellitus. Severe diabetes mellitus provoked an increase in both GLUT1 gene and protein expression in the kidneys and the heart, which was nearly normalized by glibenclamide. In the kidneys of mildly diabetic rats, an increase in the GLUT1 gene expression was neither confirmed on the protein level nor influenced by the glibenclamide treatment. In the liver of severely diabetic rats, the heart and the liver of mildly diabetic rats, the GLUT1 gene and the protein expression was changed independently of each other, which might be explained by abortive transcription, and pre- and posttranslational modifications of gene expression. The GLUT1 expression was found to be affected by the glucose and insulin levels and can be modulated by glibenclamide in severely and mildly diabetic rats. Glibenclamide can prevent the liver damage caused by severe hyperglycemia.

Changes in glucose transporter expression in monocytes of periparturient dairy cows

The transition period of dairy cows is characterized by dramatic changes in metabolism and immune cell function that contributes to increased susceptibility to several economically important diseases. Monocyte and macrophage populations increase in blood and tissues of cows during the transition period and have enhanced inflammatory responses that may contribute to increased severity of disease. Glucose is a major energy source for activated monocytes and glucose uptake is facilitated by glucose transporters (GLUT). The objective of this study was to determine how bovine monocyte GLUT expression changes during lactogenesis and in response to proinflammatory stimulation. Blood samples were collected from 10 dairy cows approximately 5wk before calving and during the first week of lactation. Monocytes were isolated from total peripheral blood mononuclear cells, and expression of GLUT1, GLUT3, and GLUT4 isoforms was assessed in resting cells and following endotoxin stimulation. In general, the onset of lactation served to decrease overall GLUT expression. Gene and protein expression of GLUT1 was significantly decreased after parturition, and GLUT3 and GLUT4 cell surface expression was also significantly decreased postcalving. Endotoxin stimulation, however, increased gene expression of GLUT3 and GLUT4, and gene expression for all GLUT isoforms was positively correlated to production of tumor necrosis factor-α. This study identified, for the first time, the presence of GLUT isoforms in bovine monocytes. Alterations in monocyte GLUT expression at the onset of lactation warrant further investigation to ascertain how changes in glucose uptake may contribute to periparturient inflammatory dysfunction.

Altered gene and protein expression of glucose transporter1 underlies dexamethasone inhibition of insulin-stimulated glucose uptake in chicken muscles1

A study was performed to characterize the effects of dexamethasone (DEX) and insulin administration on gene expression of glucose transporters (GLUT) in chicken (Gallus gallus domesticus) skeletal muscles and in cultured embryonic myoblasts. Three groups of 1-wk-old male chickens were randomly subjected to one of the following treatments for 7 d: DEX (a subcutaneous injection of 1 mg/kg BW, twice daily at 0800 h and 2000 h), controls (injected with saline), and pair-fed controls (restricted to the same feed intake as for the DEX treatment). Expressions of GLUT-1, GLUT-3, GLUT-8, and 18S rRNA mRNA were determined by quantitative reverse transcription PCR in the pectoralis major (PM) and biceps femoris (BF) muscles. Using chicken embryonic myoblasts (CEM), the interaction between DEX (200 nM) and insulin (100 nM) administration was evaluated on GLUT gene and GLUT-1 protein expressions and 2-deoxy-D-[1, 2-(3)H]-glucose (2-DG) uptake. Myoblasts were incubated with serum-free medium for 3 h in the presence or absence of insulin (0, 0.02, 0.1, 0.5, and 2.5 μM). Although GLUT-1 is not considered an insulin-responsive GLUT in mammals, this study shows that insulin stimulated 2-DG uptake and GLUT-1 mRNA and protein expression in CEM (P < 0.0001), suggesting that both are regulated in chicken skeletal muscle. Dexamethasone inhibited insulin-stimulated glucose uptake in CEM (P < 0.0001), likely accounting for insulin resistance in skeletal muscles. The results of the present study indicate that the altered GLUT-1 gene and protein expression may contribute to the insulin resistance induced by DEX treatment in chicken muscles.

N-3 fatty acids, neuronal activity and energy metabolism in the brain

The content of docosahexaenoic acid (DHA) in brain membranes is of crucial importance for the optimum development of brain functions. A lack of DHA accretion in the brain is accompanied by deficits in learning behavior linked to impairments in neurotransmission processes, which might result from alteration of brain fuel supply and hence energy metabolism. Experimental data we published support the hypothesis that n-3 fatty acids may modulate brain glucose utilization and metabolism. Indeed rats made deficient in DHA by severe depletion of total n-3 fatty acid intake have 1) a lower brain glucose utilization, 2) a decrease of the glucose transporter protein content GLUT1 both in endothelial cells and in astrocytes, 3) a repression of GLUT1 gene expression in basal state as well as upon neuronal activation. This could be due to the specific action of DHA on the regulation of GLUT1 expression since rat brain endothelial cells cultured with physiological doses of DHA had an increased GLUT1 protein content and glucose transport when compared to non-supplemented cells. These experimental data highlight the impact of n-3 fatty acids on the use of brain glucose, thereby constituting a key factor in the control of synaptic activity. This emerging role suggests that dietary intake of n-3 fatty acids can help to reduce the cognitive deficits in the elderly and possibly symptomatic cerebral metabolic alterations in Alzheimer disease by promoting brain glucose metabolism.

Gene expression profiles of tumor regression grade in locally advanced rectal cancer after neoadjuvant chemoradiotherapy

Tumor regression grading (TRG) reportedly has prognostic value in rectal cancer patients after pre-operative chemoradiotherapy (CRT). The aim of this retrospective study was to differentiate gene expression profiles based on TRG in residual cancer cells after CRT. We evaluated pathological response using the criteria of four TRG systems: the Japanese Society for the Cancer of Colon and Rectum (JSCCR), Mandard, Dworak and Rödel. Total RNA was obtained using microdissection from 52 locally advanced rectal cancer specimens from patients who underwent pre-operative CRT to examine the expression levels of 20 genes [PCNA, MKI67, CDKN1A (p21Cip1), CDK2, CHEK1, PDRG1, LGR5, PROM1 (CD133), CD44, SOX2, POU5F1 (OCT4), LKB1, VEGF, EGFR, HGF, MET, HIF1, GLUT1, BAX and BCL2] using real-time quantitative RT-PCR. Gene expression was compared across the four TRG systems. LGR5 gene expression levels in CRT non-responders were significantly higher than in responders in all four grading systems. Patients with elevated PDRG1 and GLUT1 gene expression had poor pathological response in three TRG systems (JSCCR, Dworak and Rödel). MKI67 gene expression in non-responders was significantly higher than in responders in two grading systems (JSCCR and Rödel). While, BAX gene expression in responders was significantly higher than in non-responders in the Mandard TRG system. The results of this study suggest that TRG may reflect characteristics, such as proliferative activity, stemness potency and resistance to hypoxia, of residual cancer cells following pre-operative CRT.

Polyphenols in madhumega chooranam, a Siddha medicine, ameliorates carbohydrate metabolism and oxidative stress in type II diabetic rats

Ethnopharmacological relevancePresent study was undertaken to demonstrate the mode of anti-diabetic action of a polyherbal Siddha Medicine, Madhumega chooranam (MMC). Materials and methodsMMC was fractionated into phenolic (PMMC) and non-phenolic (NPMMC) portions in order to identify bioactive fraction. Study was performed in type II diabetic rats. Role of PMMC and NPMMC on liver glucose-6-phosphatase, fructose-1,6-bisphosphatase, glucokinase and glycogen content were determined. Their role on superoxide dismutase, reduced glutathione and lipid peroxidation were investigated. In addition, their effects on GLUT4 and PPARγ gene expression were studied. Pancreas and liver histopathology was studied using hematoxylin and eosin stain. ResultsPMMC improved carbohydrate metabolism by decreasing glucose-6-phosphatase and fructose-1,6-bisphosphatase and increasing glucokinase and glycogen contents in diabetic rats liver. It alleviated oxidative stress by increasing superoxide dismutase, glutathione and decreasing lipid peroxidation content. PMMC up-regulated liver GLUT4 and PPARγ mRNA expression in comparison to the vehicle or NPMMC rats. ConclusionMadhumega chooranam mediates its anti-diabetic action through the inhibition of gluconeogenesis and activation of glycolytic pathways in type II diabetic rats. Increased GLUT4 and PPARγ expressions provide additional information on its glucose uptake/sensitising and hypolipidemic potential. Phenolic components of MMC were found to be the bioactive principles.

N-3 PUFA status affects expression of genes involved in neuroenergetics differently in the fronto-parietal cortex compared to the CA1 area of the hippocampus: Effect of rest and neuronal activation in the rat

n-3 Polyunsaturated fatty acids (PUFA) support whole brain energy metabolism but their impact on neuroenergetics in specific brain areas and during neuronal activation is still poorly understood. We tested the effect of feeding rats as control, n-3 PUFA-deficient diet, or docosahexaenoic acid (DHA)-supplemented diet on the expression of key genes in fronto-parietal cortex and hippocampal neuroenergetics before and after neuronal stimulation (activated) by an enriched environment. Compared to control rats, n-3 deficiency specifically repressed GLUT1 gene expression in the fronto-parietal cortex in basal state and also during neuronal activation which specifically stimulated GLUT1. In contrast, in the CA1 area, n-3 deficiency improved the glutamatergic synapse function in both neuronal states (glutamate transporters, Na+/K+ ATPase). DHA supplementation induced overexpression of genes encoding enzymes of the oxidative phosphorylation system and the F1F0 ATP synthase in the CA1 area. We conclude that n-3 deficiency repressed GLUT1 gene expression in the cerebral cortex, while DHA supplementation improved the mitochondrial ATP generation in the CA1 area of the hippocampus.