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Glucose Transporter (glucose + transporter)
Selected AbstractsEndothelially Derived Nitric Oxide Affects the Severity of Early Acetaminophen-induced Hepatic Injury in MiceACADEMIC EMERGENCY MEDICINE, Issue 5 2006Steven D. Salhanick MD Abstract Objectives: The precise mechanism of hepatocellular toxicity following acetaminophen (APAP) poisoning remains unclear. Nitric oxide is implicated in APAP toxicity as an inflammatory signaling molecule and as a precursor to the free radical peroxynitrate. The effects of inducible nitric oxide synthase (iNOS)-derived NO in APAP toxicity are known; however, the role of endothelial nitric oxide synthase (eNOS)-derived NO is unknown. The authors sought to evaluate the effect of eNOS-derived NO during APAP toxicity. Methods: C57BL6/J mice deficient in eNOS (eNOS KO) or iNOS (iNOS KO) and wild-type mice (WT) were treated with 300 mg/kg APAP. Alanine aminotransferase levels and plasma nitrate and nitrite levels were measured. Hypoxia inducible factor (HIF)-1, and Glucose Transporter 1 (Glut-1) levels were determined by Western blot. Results: Alanine aminotransferase levels were significantly elevated in all treated animals. Alanine aminotransferase levels were significantly lower in eNOS KO and iNOS KO than in treated WT animals. Plasma nitrate/nitrite levels were significantly higher in WT animals than in iNOS KO and eNOS KO animals. HIF-1, expression was increased in WT mice and decreased in iNOS KO mice. Glut-1 is a downstream, indirect marker of HIF function. Glut-1 expression was increased in WT and eNOS KO mice. Conclusions: Deficiency of either iNOS or eNOS results in decreased NO production and is associated with reduced hepatocellular injury following APAP poisoning. HIF-1, and Glut-1 levels are increased following APAP poisoning, implying that HIF-1, is functional during the pathogenic response to APAP poisoning. [source] Diagnostic value of GLUT-1 immunoreactivity to distinguish benign from malignant cystic squamous lesions of the head and neck in fine-needle aspiration biopsy materialDIAGNOSTIC CYTOPATHOLOGY, Issue 5 2004Michael F. Weiner M.D. Abstract The distinction of cystic squamous-cell carcinoma (SCC) from benign cystic squamous lesions (BCSLs) of the head and neck can be problematic on fine-needle aspiration biopsy (FNAB) material, particularly when BCSLs display epithelial reactive atypia or when SCC is well differentiated. Glucose transporter 1 (GLUT-1), a facilitative cell surface glucose transport protein, is aberrantly expressed in many cancers including oral and hypopharyngeal SCC. We evaluated the expression of GLUT-1 by immunochemistry on FNAB material to determine its value in distinguishing cystic SCC from BCSL of the head and neck. A 5-yr retrospective review of all head and neck cystic squamous lesions having FNAB specimens with cell block material, radiological studies, and histological confirmation was performed at our institution. Cell block material from 24 cystic squamous lesions, including 8 (33%) BCSL (7 branchial cleft cysts and 1 thyroglossal duct cyst[TDC]) and 16 (67%) metastatic SCCs with cystic/liquefactive degeneration, was retrieved and immunostained with anti-GLUT-1. GLUT-1 expression was considered positive when at least 10% of squamous cells exhibited distinct cell membrane reactivity. Positive GLUT-1 immunostaining was detected in all 16 SCCs and in none of the 8 BCSLs. In the carcinoma cases, the majority of malignant cells exhibited GLUT-1 reactivity; only a minor population of well-differentiated SCC cells displaying keratinization and arranged as squamous pearls did not express GLUT-1. GLUT-1 expression in cell block material can help to distinguish cystic SCCs from BCSLs of the head and neck. In conjunction with clinical and radiological correlation, GLUT-1 immunoreactivity can be an important diagnostic aid when the cytological findings are ambiguous. Diagn. Cytopathol. 2004;31:294,299. © 2004 Wiley-Liss, Inc. [source] Seizures, ataxia, developmental delay and the general paediatrician: Glucose transporter 1 deficiency syndromeJOURNAL OF PAEDIATRICS AND CHILD HEALTH, Issue 5 2006David J Coman Aim Glucose transporter 1 deficiency syndrome (GLUT1-DS) is an important condition for the general paediatrician's differential armamentarium. We describe a case series of eight patients in order to raise awareness of this treatable neurometabolic condition. The diagnosis of GLUT1-DS is suggested by a decreased absolute cerebrospinal fluid (CSF) glucose value (<2.2 mmol/L) or lowered CSF: plasma glucose ratio (<0.4). Methods This is a review of eight Queensland patients with GLUT1-DS. The clinical presentation, clinical course, laboratory investigations and treatment outcomes are discussed. Results The clinical features noted in our patient cohort include combinations of ataxia, developmental delay and a severe seizure disorder that is refractory to anticonvulsant medications. Seizures are the most common clinical manifestation and may be exacerbated by phenobarbitone. The paired CSF: plasma glucose results ranged from 0.2 to 0.39 (normal <0.6) with an average of 0.33. 3-O-Methyl-D-Glucose uptake and GLUT1 Genotyping analysis have been performed on five patients thus far. Rapid and impressive seizure control was observed in 100% of our patients once the ketogenic diet was instituted, with half of the cohort being able to wean completely from anticonvulsants. Conclusion Children presenting with a clinical phenotype consisting of a refractory seizure disorder, ataxia and developmental delay should prompt the consideration of Glucose transporter 1 deficiency syndrome. While the diagnostic test of lumbar puncture is an invasive manoeuvre, the diagnosis provides a viable treatment option, the ketogenic diet. GLUT1-DS displays clinical heterogeneity, but the value of early diagnosis and treatment is demonstrated by our patient cohort. [source] Human liver-derived cells stably modified for regulated proinsulin secretion function as bioimplants in vivoTHE JOURNAL OF GENE MEDICINE, Issue 4 2002Xiang Chen Abstract Background Insulin deficiency is currently treated with pharmacological insulin secretagogues, insulin injections or islet transplants. Secondary failure of pharmacological agents is common; insulin injections often fail to achieve euglycemic control; and islet transplants are rare. Non-, cells capable of regulated insulin secretion in vivo could be a functional cure for diabetes. Hepatocytes are good candidates, being naturally glucose-responsive, protein-secreting cells, while the liver is positioned to receive direct nutrient signals that regulate insulin production. Methods Human liver-derived Chang cells were modified with a plasmid construct in which a bifunctional promoter comprising carbohydrate response elements and the human metallothionein IIA promoter controlled human proinsulin cDNA expression. Secretory responses of stable cell clones were characterized in vitro and in vivo by proinsulin radioimmunoassay. Results Transfected Chang cells secreted 5,8,pmol proinsulin/106 cells per 24,h in continuous passage for at least a year in response to 5,25,mM glucose and 10,90,µM zinc in vitro. Glucose and zinc synergistically increased proinsulin production by up to 30-fold. Non-glucose secretagogues were also active. Glucose transporter 2 (GLUT2) and glucokinase cDNA co-transfection enhanced glucose responsiveness. Intraperitoneally implanted Chang cells secreted proinsulin in scid and Balb/c mice. Serum proinsulin levels were further increased 1.3-fold (p<0.05) after glucose and 1.4- to 1.6-fold (p<0.005) after zinc administration in vivo. Conclusions These results are the first to demonstrate stable proinsulin production in a human liver-derived cell line with activity in vitro and in vivo and provide a basis for engineering hepatocytes as in vivo bioimplants for future diabetes treatment. Copyright © 2002 John Wiley & Sons, Ltd. [source] Regulation of glucose transporter 4 traffic by energy deprivation from mitochondrial compromiseACTA PHYSIOLOGICA, Issue 1 2009A. Klip Abstract Skeletal muscle is the major store and consumer of fatty acids and glucose. Glucose enters muscle through glucose transporter 4 (GLUT4). Upon insufficient oxygen availability or energy compromise, aerobic metabolism of glucose and fatty aids cannot proceed, and muscle cells rely on anaerobic metabolism of glucose to restore cellular energy status. An increase in glucose uptake into muscle is a key response to stimuli requiring rapid energy supply. This chapter analyses the mechanisms of the adaptive regulation of glucose transport that rescue muscle cells from mitochondrial uncoupling. Under these conditions, the initial drop in ATP recovers rapidly, through a compensatory increase in glucose uptake. This adaptive response involves AMPK activation by the initial ATP drop, which elevates cell surface GLUT4 and glucose uptake. The gain in surface GLUT4 involves different signals and routes of intracellular traffic compared with those engaged by insulin. The hormone increases GLUT4 exocytosis through phosphatidylinositol 3-kinase and Akt, whereas energy stress retards GLUT4 endocytosis through AMPK and calcium inputs. Given that energy stress is a component of muscle contraction, and that contraction activates AMPK and raises cytosolic calcium, we hypothesize that the increase in glucose uptake during contraction may also involve a reduction in GLUT4 endocytosis. [source] Changes in gene expression and morphology of mouse embryonic stem cells on differentiation into insulin-producing cells in vitro and in vivoDIABETES/METABOLISM: RESEARCH AND REVIEWS, Issue 5 2009Ortwin Naujok Abstract Background Embryonic stem (ES) cells have the potential to produce unlimited numbers of surrogate insulin-producing cells for cell replacement therapy of type 1 diabetes mellitus. The impact of the in vivo environment on mouse ES cell differentiation towards insulin-producing cells was analysed morphologically after implantation. Methods ES cells differentiated in vitro into insulin-producing cells according to the Lumelsky protocol or a new four-stage differentiation protocol were analysed morphologically before and after implantation for gene expression by in situ reverse transcription polymerase chain reaction and protein expression by immunohistochemistry and ultrastructural analysis. Results In comparison with nestin positive ES cells developed according to the reference protocol, the number of ES cells differentiated with the four-stage protocol increased under in vivo conditions upon morphological analysis. The cells exhibited, in comparison to the in vitro situation, increased gene and protein expression of Pdx1, insulin, islet amyloid polypeptide (IAPP), the GLUT2 glucose transporter and glucokinase, which are functional markers for glucose-induced insulin secretion of pancreatic beta cells. Renal sub-capsular implantation of ES cells with a higher degree of differentiation achieved by in vitro differentiation with a four-stage protocol enabled further significant maturation for the beta-cell-specific markers, insulin and the co-stored IAPP as well as the glucose recognition structures. In contrast, further in vivo differentiation was not achieved with cells differentiated in vitro by the reference protocol. Conclusions A sufficient degree of in vitro differentiation is an essential prerequisite for further substantial maturation in a beta-cell-specific way in vivo, supported by cell-cell contacts and vascularisation. Copyright © 2009 John Wiley & Sons, Ltd. [source] An adipocentric view of signaling and intracellular traffickingDIABETES/METABOLISM: RESEARCH AND REVIEWS, Issue 5 2002Silvia Mora Abstract Adipocytes have traditionally been considered to be the primary site for whole body energy storage mainly in the form of triglycerides and fatty acids. This occurs through the ability of insulin to markedly stimulate both glucose uptake and lipogenesis. Conventional wisdom held that defects in fuel partitioning into adipocytes either because of increased adipose tissue mass and/or increased lipolysis and circulating free fatty acids resulted in dyslipidemia, obesity, insulin resistance and perhaps diabetes. However, it has become increasingly apparent that loss of adipose tissue (lipodystrophies) in both animal models and humans also leads to metabolic disorders that result in severe states of insulin resistance and potential diabetes. These apparently opposite functions can be resolved by the establishment of adipocytes not only as a fuel storage depot but also as a critical endocrine organ that secretes a variety of signaling molecules into the circulation. Although the molecular function of these adipocyte-derived signals are poorly understood, they play a central role in the maintenance of energy homeostasis by regulating insulin secretion, insulin action, glucose and lipid metabolism, energy balance, host defense and reproduction. The diversity of these secretory factors include enzymes (lipoprotein lipase (LPL) and adipsin), growth factors [vascular endothelial growth factor (VEGF)], cytokines (tumor necrosis factor-,, interleukin 6) and several other hormones involved in fatty acid and glucose metabolism (leptin, Acrp30, resistin and acylation stimulation protein). Despite the large number of molecules secreted by adipocytes, our understanding of the pathways and mechanisms controlling intracellular trafficking and exocytosis in adipocytes is poorly understood. In this article, we will review the current knowledge of the trafficking and secretion processes that take place in adipocytes, focusing our attention on two of the best characterized adipokine molecules (leptin and adiponectin) and on one of the most intensively studied regulated membrane proteins, the GLUT4 glucose transporter. Copyright © 2002 John Wiley & Sons, Ltd. [source] The mode of action of thiazolidinediones,DIABETES/METABOLISM: RESEARCH AND REVIEWS, Issue S2 2002Hans Hauner Abstract The thiazolidinediones (TZDs) or ,glitazones' are a new class of oral antidiabetic drugs that improve metabolic control in patients with type 2 diabetes through the improvement of insulin sensitivity. TZDs exert their antidiabetic effects through a mechanism that involves activation of the gamma isoform of the peroxisome proliferator-activated receptor (PPAR,), a nuclear receptor. TZD-induced activation of PPAR, alters the transcription of several genes involved in glucose and lipid metabolism and energy balance, including those that code for lipoprotein lipase, fatty acid transporter protein, adipocyte fatty acid binding protein, fatty acyl-CoA synthase, malic enzyme, glucokinase and the GLUT4 glucose transporter. TZDs reduce insulin resistance in adipose tissue, muscle and the liver. However, PPAR, is predominantly expressed in adipose tissue. It is possible that the effect of TZDs on insulin resistance in muscle and liver is promoted via endocrine signalling from adipocytes. Potential signalling factors include free fatty acids (FFA) (well-known mediators of insulin resistance linked to obesity) or adipocyte-derived tumour necrosis factor-, (TNF-,), which is overexpressed in obesity and insulin resistance. Although there are still many unknowns about the mechanism of action of TZDs in type 2 diabetes, it is clear that these agents have the potential to benefit the full ,insulin resistance syndrome' associated with the disease. Therefore, TZDs may also have potential benefits on the secondary complications of type 2 diabetes, such as cardiovascular disease. Copyright © 2002 John Wiley & Sons, Ltd. [source] Lighting up insulin actionDIABETIC MEDICINE, Issue 4 2001J. M. Tavaré Summary Understanding the mechanism of insulin action remains one of the most important challenges in modern medical biology. Recent advances in cell imaging techniques, increased processing power of computers and the internet, and the introduction of novel fluorescent reagents such as green fluorescent proteins (GFPs) have revolutionized our ability to scrutinize insulin action by time-lapse microscopy at the single-cell level. This article outlines some of the advances made in the authors' laboratory, with particular reference to imaging the movements of the insulin-sensitive glucose transporter, GLUT4, and the generation of phosphoinositide lipids. [source] Involvement of astroglial ceramide in palmitic acid-induced Alzheimer-like changes in primary neuronsEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 8 2007Sachin Patil Abstract A high-fat diet has been shown to significantly increase the risk of the development of Alzheimer's disease (AD), a neurodegenerative disease histochemically characterized by the accumulation of amyloid beta (A,) protein in senile plaques and hyperphosphorylated tau in neurofibrillary tangles. Previously, we have shown that saturated free fatty acids (FFAs), palmitic and stearic acids, caused increased amyloidogenesis and tau hyperphosphorylaion in primary rat cortical neurons. These FFA-induced effects observed in neurons were found to be mediated by astroglial FFA metabolism. Therefore, in the present study we investigated the basic mechanism relating astroglial FFA metabolism and AD-like changes observed in neurons. We found that palmitic acid significantly increased de-novo synthesis of ceramide in astroglia, which in turn was involved in inducing both increased production of the A, protein and hyperphosphorylation of the tau protein. Increased amyloidogenesis and hyperphoshorylation of tau lead to formation of the two most important pathophysiological characteristics associated with AD, A, or senile plaques and neurofibrillary tangles, respectively. In addition to these pathophysiological changes, AD is also characterized by certain metabolic changes; abnormal cerebral glucose metabolism is one of the distinct characteristics of AD. In this context, we found that palmitic acid significantly decreased the levels of astroglial glucose transporter (GLUT1) and down-regulated glucose uptake and lactate release by astroglia. Our present data establish an underlying mechanism by which saturated fatty acids induce AD-associated pathophysiological as well as metabolic changes, placing ,astroglial fatty acid metabolism' at the center of the pathogenic cascade in AD. [source] Dictyostelium differentiation-inducing factor-1 induces glucose transporter 1 translocation and promotes glucose uptake in mammalian cellsFEBS JOURNAL, Issue 13 2007Waka Omata The differentiation-inducing factor-1 (DIF-1) is a signal molecule that induces stalk cell formation in the cellular slime mold Dictyostelium discoideum, while DIF-1 and its analogs have been shown to possess antiproliferative activity in vitro in mammalian tumor cells. In the present study, we investigated the effects of DIF-1 and its analogs on normal (nontransformed) mammalian cells. Without affecting the cell morphology and cell number, DIF-1 at micromolar levels dose-dependently promoted the glucose uptake in confluent 3T3-L1 fibroblasts, which was not inhibited with wortmannin or LY294002 (inhibitors for phosphatidylinositol 3-kinase). DIF-1 affected neither the expression level of glucose transporter 1 nor the activities of four key enzymes involved in glucose metabolism, such as hexokinase, fluctose 6-phosphate kinase, pyruvate kinase, and glucose 6-phosphate dehydrogenase. Most importantly, stimulation with DIF-1 was found to induce the translocation of glucose transporter 1 from intracellular vesicles to the plasma membranes in the cells. In differentiated 3T3-L1 adipocytes, DIF-1 induced the translocation of glucose trasporter 1 (but not of glucose transporter 4) and promoted glucose uptake, which was not inhibited with wortmannin. These results indicate that DIF-1 induces glucose transporter 1 translocation and thereby promotes glucose uptake, at least in part, via a inhibitors for phosphatidylinositol 3-kinase/Akt-independent pathway in mammalian cells. Furthermore, analogs of DIF-1 that possess stronger antitumor activity than DIF-1 were less effective in promoting glucose consumption, suggesting that the mechanism of the action of DIF-1 for stimulating glucose uptake should be different from that for suppressing tumor cell growth. [source] Immunodetection of GLUT1, p63 and phospho-histone H1 in invasive head and neck squamous carcinoma: correlation of immunohistochemical staining patterns with keratinizationHISTOPATHOLOGY, Issue 6 2006D E Burstein Aims :,To examine invasive head and neck squamous carcinomas for expression of GLUT1, a glucose transporter and marker of increased glucose uptake, glycolytic metabolism and response to tissue hypoxia; p63, a p53 homologue that is a marker of the undifferentiated proliferative basaloid phenotype; and phospho-histone H1, a marker of activation of the cell cycle-promoting cyclin-dependent kinases 1 and 2. Methods :,Routinely processed slides from 34 invasive squamous carcinomas, including 25 with intraepithelial components, were immunostained with anti-GLUT1 (Chemicon), anti-p63 (4A4, Santa Cruz), and antiphospho-histone H1 (monoclonal 12D11). Results :,In keratinizing carcinomas, all three markers were most commonly immunodetected peripherally, with loss of expression in central keratinized zones. In contrast, in non-keratinizing carcinomas, p63 and phospho-histone H1 expression was most commonly observed throughout tumour nests and anti-GLUT1 stained in a pattern suggestive of hypoxia-induced expression (,antistromal' staining), in which cells at the tumour,stromal interface were GLUT1, and cells in central, perinecrotic zones showed progressive induction of GLUT1. Intraepithelial components also displayed basal and ,antibasal' GLUT1 staining patterns, homologous to the pro- and antistromal patterns in invasive carcinoma; basal patterns in intraepithelial lesions appeared to be more predictive of keratinizing invasive carcinoma and antibasal intraepithelial staining more predictive of non-keratinizing poorly differentiated carcinomas. Conclusions :,Keratinizing and non-keratinizing squamous carcinomas differ in expression patterns of GLUT1, p63 and phospho-histone H1. In the former, all three markers were typically suppressed in conjunction with keratinization; in the latter, GLUT1 expression was more likely to occur in a hypoxia-inducible pattern and expression of p63 and phospho-histone H1 was unsuppressed. GLUT1 expression patterns in intraepithelial lesions may be predictive of the differentiation status of the associated invasive carcinoma. [source] Signaling mechanisms in skeletal muscle: Acute responses and chronic adaptations to exerciseIUBMB LIFE, Issue 3 2008Katja S.C. Röckl Abstract Physical activity elicits physiological responses in skeletal muscle that result in a number of health benefits, in particular in disease states, such as type 2 diabetes. An acute bout of exercise/muscle contraction improves glucose homeostasis by increasing skeletal muscle glucose uptake, while chronic exercise training induces alterations in the expression of metabolic genes, such as those involved in muscle fiber type, mitochondrial biogenesis, or glucose transporter 4 (GLUT4) protein levels. A primary goal of exercise research is to elucidate the mechanisms that regulate these important metabolic and transcriptional events in skeletal muscle. In this review, we briefly summarize the current literature describing the molecular signals underlying skeletal muscle responses to acute and chronic exercise. The search for possible exercise/contraction-stimulated signaling proteins involved in glucose transport, muscle fiber type, and mitochondrial biogenesis is ongoing. Further research is needed because full elucidation of exercise-mediated signaling pathways would represent a significant step toward the development of new pharmacological targets for the treatment of metabolic diseases such as type 2 diabetes. © 2008 IUBMB IUBMB Life, 60(3): 145,153, 2008 [source] The Complementary Membranes Forming the Blood-Brain BarrierIUBMB LIFE, Issue 3 2002Richard A. Hawkins Abstract Brain capillary endothelial cells form the blood-brain barrier. They are connected by extensive tight junctions, and are polarized into luminal (blood-facing) and abluminal (brain-facing) plasma membrane domains. The polar distribution of transport proteins allows for active regulation of brain extracellular fluid. Experiments on isolated membrane vesicles from capillary endothelial cells of bovine brain demonstrated the polar arrangement of amino acid and glucose transporters, and the utility of such arrangements have been proposed. For instance, passive carriers for glutamine and glutamate have been found only in the luminal membrane of blood-brain barrier cells, while Na-dependent secondary active transporters are at the abluminal membrane. This organization could promote the net removal of nitrogen-rich amino acids from brain, and account for the low level of glutamate penetration into the central nervous system. Furthermore, the presence of a ,-glutamyl cycle at the luminal membrane and Na-dependent amino acid transporters at the abluminal membrane may serve to modulate movement of amino acids from blood-to-brain. Passive carriers facilitate amino acid transport into brain. However, activation of the ,-glutamyl cycle by increased plasma amino acids is expected to generate oxoproline within the blood-brain barrier. Oxoproline stimulates secondary active amino acid transporters (Systems A and B o,+ ) at the abluminal membrane, thereby reducing net influx of amino acids to brain. Finally, passive glucose transporters are present in both the luminal and abluminal membranes of the blood-brain barrier. Interestingly, a high affinity Na-dependent glucose carrier has been described only in the abluminal membrane. This raises the question whether glucose entry may be regulated to some extent. Immunoblotting studies suggest more than one type of passive glucose transporter exist in the blood-brain barrier, each with an asymmetrical distribution. In conclusion, it is now clear that the blood-brain barrier participates in the active regulation of brain extracellular fluid, and that the diverse functions of each plasma membrane domain contributes to these regulatory functions. [source] TCDD suppresses insulin-responsive glucose transporter (GLUT-4) gene expression through C/EBP nuclear transcription factors in 3T3-L1 adipocytesJOURNAL OF BIOCHEMICAL AND MOLECULAR TOXICOLOGY, Issue 2 2006Phillip Chin-Chen Liu Abstract TCDD is known to reduce significantly the level of the functionally active form of glucose transporter type 4 (GLUT4) in vivo in adipose tissue and muscles. To study the mechanistic basis of this phenomenon, we conducted transient transfection and DNA deletion analysis in 3T3-L1 cells using chloramphenicol acetyltransferase (CAT) reporter plasmids containing the GLUT4 promoter joined to the bacterial CAT. It was found that in transfected control samples, CAT activity was significantly higher in cells transfected with p469CAT and p273CAT than those with p78CAT, indicating that the region between ,78 and ,273 contained elements that play major roles in transactivation of this gene. Treatment with TCDD decreased CAT activity with p469CAT and p273CAT, but not with p78CAT, indicating the same region to contain the element(s) affected by TCDD. A gel-shift (EMSA) analysis result indicated that TCDD shows the profound effect only on the nuclear proteins binding to the [32P]-labeled probe containing C/EBP response element equivalent of the ,265 to ,242 stretch of the GLUT4 promoter. The results of supershift analysis showed that TCDD caused a decrease in the tier of C/EBP, and an increase in that of C/EBP, among the proteins bound to this C/EBP response element. We studied the effect of TCDD in cells overexpressing either C/EBP,, C/EBP,, or C/EBP, through transient transfection of p273CAT or p469CAT. The results clearly showed that the effect of TCDD to suppress the CAT activity of p273 or p469 disappeared in those cells overexpressing C/EBP, or C/EBP,. These results implicate the C/EBP proteins to be the main mediator of suppressive action of TCDD on GLUT4 gene expression in 3T3-L1 cells. © 2006 Wiley Periodicals, Inc. J Biochem Mol Toxicol 20:79,87, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/jbt.20120 [source] Expression of GLUT8 in mouse intestine: Identification of alternative spliced variantsJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 6 2009Amparo Romero Abstract GLUT8 is a facilitative glucose transporter composed of 10 exons coding for a 477 amino acids protein. It is mainly expressed in the testis, but it has also been studied in a number of tissues such as brain, adipose tissue, and liver. In this work, we have characterized the expression of GLUT8 in the small and large intestine under normal physiological conditions. Protein assay revealed low GLUT8 protein levels in the intestine compared to the testis, with higher levels in the colon than in the small intestine. Immunohistochemistry studies showed an intracellular localization of GLUT8 in enterocytes and colonocytes with a supranuclear distribution next to the apical membrane. GLUT8 immunoreactivity was also detected in the crypt cells. Interestingly, we have identified three additional transcriptional variants in mouse intestine (mGLUT-SP1, mGLUT8-SP2, and mGLUT8-SP3) produced by the deletion of one, two, and four exons, respectively, whereas only the entire mRNA was detected in the testis. Expression of these alternative variants did not have an effect on glucose consumption in 3T3-L1 cells. Although the specific function of GLUT8 in intestine remains unclear, the alternative splicing of GLUT8 could reflect a mechanism for the regulation of the gene expression in a tissue-specific manner by targeting GLUT8 mRNA for nonsense-mediated decay. J. Cell. Biochem. 106: 1068,1078, 2009. © 2009 Wiley-Liss, Inc. [source] Alzheimer-like changes in protein kinase B and glycogen synthase kinase-3 in rat frontal cortex and hippocampus after damage to the insulin signalling pathwayJOURNAL OF NEUROCHEMISTRY, Issue 4 2006Melita Salkovic-Petrisic Abstract The insulin-resistant brain state is related to late-onset sporadic Alzheimer's disease, and alterations in the insulin receptor (IR) and its downstream phosphatidylinositol-3 kinase signalling pathway have been found in human brain. These findings have not been confirmed in an experimental model related to sporadic Alzheimer's disease, for example rats showing a neuronal IR deficit subsequent to intracerebroventricular (i.c.v.) treatment with streptozotocin (STZ). In this study, western blot analysis performed 1 month after i.c.v. injection of STZ showed an increase of 63% in the level of phosphorylated glycogen synthase kinase-3,/, (pGSK-3,/,) protein in the rat hippocampus, whereas the levels of the unphosphorylated form (GSK-3,/,) and protein kinase B (Akt/PKB) remained unchanged. Three months after STZ treatment, pGSK-3,/, and Akt/PKB levels tended to decrease (by 8 and 9% respectively). The changes were region specific, as a different pattern was found in frontal cortex. Structural alterations were also found, characterized by ,-amyloid peptide-like aggregates in brain capillaries of rats treated with STZ. Similar neurochemical changes and cognitive deficits were recorded in rats treated with i.c.v. 5-thio- d -glucose, a blocker of glucose transporter (GLUT)2, a transporter that is probably involved in brain glucose sensing. The IR signalling cascade alteration and its consequences in rats treated with STZ are similar to those found in humans with sporadic Alzheimer's disease, and our results suggest a role for GLUT2 in Alzheimer's pathophysiology. [source] Membrane localization itself but not binding to IICBGlc is directly responsible for the inactivation of the global repressor Mlc in Escherichia coliMOLECULAR MICROBIOLOGY, Issue 3 2004Yuya Tanaka Summary Mlc is a global transcriptional repressor involved in the regulation of genes linked to glucose metabolism. The activity of Mlc is modulated through the interaction with a major glucose transporter, IICBGlc, in response to external glucose. To understand how IICBGlc,Mlc interaction controls the repressor activity of Mlc, we attempted to isolate Mlc mutants that retain the ability to repress target genes even in the presence of glucose. The Mlc mutants were tested for their ability to interact with IICBGlc. Mutants in which a single amino acid substitution occurs in the N-terminal portion were no longer able to bind to IICBGlc, suggesting that the N-terminal region of Mlc is primarily responsible for the interaction with IICBGlc. To examine whether the Mlc,IICBGlc interaction and/or the membrane localization of Mlc per se are essential for the inactivation of Mlc, the properties of several hybrid proteins in which either IIBGlc or Mlc is fused to membrane proteins were analysed. The cytoplasmic IIBGlc domain failed to inhibit the Mlc action although it retains the ability to bind Mlc in cells. However, it gained the ability to inhibit the Mlc activity when it was fused to a membrane protein LacY. In addition, we showed that Mlc is inactivated when fused to membrane proteins but not when fused to cytoplasmic proteins. We conclude that the IICBGlc,Mlc interaction is dispensable for the inactivation of Mlc, and that membrane localization is directly responsible for the inactivation of Mlc. [source] Sodium/iodide symporter expression in primary lung cancer and comparison with glucose transporter 1 expressionPATHOLOGY INTERNATIONAL, Issue 2 2009Do Y. Kang The aim of the present study was to evaluate the expression of sodium/iodide symporter (NIS) and glucose transporter 1 (Glut1) in 139 primary lung cancers on immunohistochemistry, and to determine the diagnostic utility of NIS as an imaging reporter. Immunoreactivity for NIS and Glut1 was noted in 75 (54.0%) and 72 (51.8%) of the 139 cases, respectively. Analysis of NIS expression on Western blot confirmed the immunohistochemistry. NIS expression was significantly higher in the adenocarcinomas than in the other carcinomas, and Glut1 expression was significantly higher in the squamous cell carcinomas than in the other carcinomas (each P < 0.0001). The frequency of NIS expression in those carcinomas lacking Glut1 expression was significantly higher than in those with Glut1 expression (P = 0.012). Among 64 adenocarcinomas, the frequency of the NIS(+)/Glut1(,) phenotype was 61.0%, which was the most frequent expression pattern. By studying the expression pattern of NIS in lung cancer, the present paper provides a helpful foundation for examining the potential utility of NIS-mediated radioiodide as an alternative diagnostic modality, especially for the management of patients with lung adenocarcinoma lacking Glut1 expression. [source] Insulin-Producing Cells Derived from Rat Bone Marrow and Their Autologous Transplantation in the Duodenal Wall for Treating DiabetesTHE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 5 2009Yu-Hua Zhang Abstract Islet cell transplantation is one of the most promising therapies for diabetes mellitus (DM). However, the limited availability of purified islets for transplantation and the risk of immunological rejection severely limit its use. In vitro transdifferentiation of autologous bone marrow-derived mesenchymal stem cells (BMSCs) into insulin-producing cells (IPCs) could provide an abundant source of cells for this procedure and avoid immunological rejection. Here, we isolated and characterized BMSCs and induced their in vitro differentiation into IPCs. Reverse-transcription polymerase chain reaction analysis revealed that these IPCs could express Ins1, Ins2, glucagon, glucose transporter 2, and pancreatic duodenal homeobox-1. Insulin production by the IPCs was confirmed by immunocytochemistry and Western blot analysis. On this basis, donor rats supplying BMSCs were made diabetic by a single intraperitoneal injection of streptozotocin. The IPCs were then autologously transplanted into the duodenal submucosa of diabetic rats. Grafted cells could be visualized in sections after 2, 4, and 8 weeks by immunohistochemical staining for insulin. Furthermore, in the IPC-implanted group, hyperglycemia was normalized, compared with a persistent increase in glucose levels in the diabetic group and intraperitoneal glucose tolerance test-induced responses were observed in the IPC-implanted group. These results on autologous transplantation of IPCs derived from BMSCs into the duodenal wall could offer a novel potential therapeutical protocol for DM. Anat Rec, 292:728,735, 2009. © 2009 Wiley-Liss, Inc. [source] Quantitative trait loci with additive effects on palatability and fatty acid composition of meat in a Wagyu,Limousin F2 populationANIMAL GENETICS, Issue 5 2007L. J. Alexander Summary A whole-genome scan was conducted on 328 F2 progeny in a Wagyu × Limousin cross to identify quantitative trait loci (QTL) affecting palatability and fatty acid composition of beef at an age-constant endpoint. We have identified seven QTL on five chromosomes involved in lipid metabolism and tenderness. None of the genes encoding major enzymes involved in fatty acid metabolism, such as fatty acid synthase (FASN), acetyl-CoA carboxylase alpha (ACACA), solute carrier family 2 (facilitated glucose transporter) member 4 (SLC2A4), stearoyl-CoA desaturase (SCD) and genes encoding the subunits of fatty acid elongase, was located in these QTL regions. The present study may lead to a better-tasting and healthier product for consumers through improved selection for palatability and lipid content of beef. [source] Early-onset absence epilepsy caused by mutations in the glucose transporter GLUT1,ANNALS OF NEUROLOGY, Issue 3 2009Arvid Suls MSc Absence epilepsies of childhood are heterogeneous with most cases following complex inheritance. Those cases with onset before 4 years of age represent a poorly studied subset. We screened 34 patients with early-onset absence epilepsy for mutations in SLC2A1, the gene encoding the GLUT1 glucose transporter. Mutations leading to reduced protein function were found in 12% (4/34) of patients. Two mutations arose de novo, and two were familial. These findings suggest GLUT1 deficiency underlies a significant proportion of early-onset absence epilepsy, which has both genetic counseling and treatment implications because the ketogenic diet is effective in GLUT1 deficiency. Ann Neurol 2009;66:415,419 [source] Expression, purification, crystallization and preliminary X-ray analysis of the EIICGlc domain of the Escherichia coli glucose transporterACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 6 2010Andreas Zurbriggen The glucose-import system of Escherichia coli consists of a hydrophilic EIIAGlc subunit and a transmembrane EIICBGlc subunit. EIICBGlc (UniProt P69786) contains two domains: the transmembrane EIICGlc domain (40.6,kDa) and the cytoplasmic EIIBGlc domain (8.0,kDa), which are fused by a linker that is strongly conserved among its orthologues. The EIICBGlc subunit can be split within this motif by trypsin. Here, the crystallization of the tryptic EIICGlc domain is described. A complete data set was collected to 4.5,Å resolution at 100,K. [source] The isoflavonoid aglycone-rich fractions of Chungkookjang, fermented unsalted soybeans, enhance insulin signaling and peroxisome proliferator-activated receptor-, activity in vitroBIOFACTORS, Issue 4 2006Dae Young Kwon Abstract We investigated anti-diabetic candidates and their mechanisms from the fractions of Chungkookjang (CKJ), a traditional fermented unsalted soybean, by investigating insulin signaling, peroxisome proliferator-activated receptor (PPAR)-, activity and glucose-stimulated insulin secretion, in vitro. Cooked soybeans (CSB) and CKJ, fermented predominantly with Bacillus subtilis, were extracted by 70% EtOH followed by an XAD-4 column chromatography with a serial mixture of solvents comprised of MeOH and water. During fermentation, the contents of isoflavonoid aglycones were elevated, and the fractions enriched with aglycones enhanced insulin-stimulated glucose uptake in 3T3-L1 adipocytes. This increase in glucose uptake resulted from stimulating a translocation of the glucose transporter (GLUT)-4 into the plasma membrane through the phosphorylation of insulin receptor substrate (IRS)-1 and Akt. Especially, daidzein enriched fractions elevated insulin-stimulated glucose uptake by acting as PPAR-, agonist up to levels exhibited when 10 nM insulin is administered. Fractions containing small peptides with low polarity in CKJ slightly increased glucose-stimulated insulin secretion. The data suggest that an increase in isoflavonoid aglycones in CKJ, in comparison to CSB, enhances glucose utilization via activating insulin signaling and stimulates PPAR-, activity in adipocytes. In addition, CKJ contains small peptides improving glucose-stimulated insulin secretion in insulinoma cells. Overall, CKJ is superior to CSB in anti-diabetic action. [source] Effects of retinoids and thiazolidinediones on proliferation, insulin release, insulin mRNA, GLUT 2 transporter protein and mRNA of INS-1 cellsCELL BIOCHEMISTRY AND FUNCTION, Issue 3 2001J. Blumentrath Abstract Both 9-cis-retinoic acid (9cRA) and all-trans-retinoic acid (ATRA) are active metabolites of vitamin A (retinol). There exists an interaction between retinoid receptors and peroxisome proliferator-activated receptors (PPAR,). To define their functions in an insulin secreting system the effects of ATRA, 9cRA and the PPAR, agonist rosiglitazone on cell proliferation, insulin release and glucose transporter (GLUT) 2 of INS-1 cells were tested. Retinoic acid receptor (RAR-, and -,) and retinoid X receptor (RXR-, and -,) proteins are present (immunoblots). Both 9cRA and ATRA inhibit INS-1 cell proliferation ([3H]-thymidine assay) in a concentration dependent manner. Both 9cRA and ATRA increased insulin release, but only ATRA ralsed the GLUT 2 mRNA in a bell-shaped concentration response curve after 48,h. The insulinotropic effect of one compound is not significantly superimposed by the other indicating that the same binding sites are used by 9cRA and ATRA. The acute and chronic effects of the PPAR, agonist rosiglitazone on insulin release were additionally determined since glitazones act as transcription factors together with RXR agonists. At high concentrations (100,,m) rosiglitazone inhibited glucose (8.3,mm) stimulated insulin secretion (acute experiment over 60,min). Insulin secretion, however, was increased during a 24,h treatment at a concentration of 10,,m and again inhibited at 100,,m. Changes in preproinsulin mRNA expression were not observed. Rosiglitazone (100,,m) increased GLUT 2 mRNA paralleled by an increase of GLUT 2 protein, but only after 24,h of treatment. This data indicate that RAR and RXR mediate insulin release. The changes in GLUT 2 have no direct impact on insulin release; the inhibition seen at high concentrations of either compound is possibly the result of the observed inhibition of cell proliferation. Effects of rosiglitazone on preproinsulin mRNA and GLUT 2 (mRNA and protein) do not play a role in modulating insulin secretion. With the presence of an RXR receptor agonist the effect of rosiglitazone on insulin release becomes stimulatory. Thus the effects of RAR-, RXR agonists and rosiglitazone depend on their concentrations, the duration of their presence and are due to specific interactions. Copyright © 2001 John Wiley & Sons, Ltd. [source] An efficient experimental strategy for mouse embryonic stem cell differentiation and separation of a cytokeratin-19-positive population of insulin-producing cellsCELL PROLIFERATION, Issue 4 2008O. Naujok Objectives: Embryonic stem cells are a potential source for insulin-producing cells, but existing differentiation protocols are of limited efficiency. Here, the aim has been to develop a new one, which drives development of embryonic stem cells towards insulin-producing cells rather than to neuronal cell types, and to combine this with a strategy for their separation from insulin-negative cells. Materials and methods: The cytokeratin-19 (CK19) promoter was used to control the expression of enhanced yellow fluorescence protein in mouse embryonic stem cells during their differentiation towards insulin-producing cells, using a new optimized four-stage protocol. Two cell populations, CK19+ and CK19, cells, were successfully fluorescence sorted and analysed. Results: The new method reduced neuronal progeny and suppressed differentiation into glucagon- and somatostatin-producing cells. Concomitantly, ,-cell like characteristics of insulin-producing cells were strengthened, as documented by high gene expression of the Glut2 glucose transporter and the transcription factor Pdx1. This novel protocol was combined with a cell-sorting technique. Through the combined procedure, a fraction of glucose-responsive insulin-secreting CK19+ cells was obtained with 40-fold higher insulin gene expression and 50-fold higher insulin content than CK19, cells. CK19+ cells were immunoreactive for C-peptide and had ultrastructural characteristics of an insulin-secretory cell. Conclusion: Differentiated CK19+ cells reflect an endocrine precursor cell type of ductal origin, potentially suitable for insulin replacement therapy in diabetes. [source] Inhibition of calcineurin increases monocarboxylate transporters 1 and 4 protein and glycolytic enzyme activities in rat soleus muscleCLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 3 2005Masataka Suwa SUMMARY 1.,The present study was designed to examine the role of calcineurin in muscle metabolic components by the administration of the specific calcineurin inhibitor cyclosporine A (CsA) to rats. 2.,Male Wistar rats were divided into either a CsA-treated group (CT) or a vehicle-treated group (VT). Cyclosporine A was administered subcutaneously to rats at a rate of 25 mg/kg bodyweight per day for 10 successive days. Thereafter, changes in muscle enzyme activities and glucose transporter (GLUT)-4 and monocarboxylate transporter (MCT)-1 and MCT-4 proteins in the slow-twitch soleus and fast-twitch extensor digitorum longus (EDL) muscles were examined. 3.,There was a significant increase in MCT-1 and MCT-4 proteins in the soleus muscle in the CT group, but not in the EDL muscle. The activities of hexokinase, pyruvate kinase and lactate dehydrogenase in the soleus muscle also increased significantly in the CT group, but a similar increase in enzyme activity was not seen in EDL muscle. The activities of citrate synthase or malate dehydrogenase and the GLUT-4 protein content were not altered by CsA treatment in either the soleus or EDL muscles. 4.,These results seem to imply that calcineurin negatively regulates the components of glucose/lactate metabolism, except for GLUT-4, especially in slow-twitch muscle. [source] Effect of drug-induced cytotoxicity on glucose uptake in Hodgkin's lymphoma cellsEUROPEAN JOURNAL OF HAEMATOLOGY, Issue 2 2006Ursula Banning Abstract:,Background:,In Hodgkin's lymphoma, F-18-fluoro-deoxy- d -glucose positron emission tomography (FDG-PET) is used for staging and response evaluation after chemotherapy. However, drug-mediated downregulation of glucose uptake in viable Hodgkin's lymphoma cells might limit the use of FDG-PET. Methods:,We analyzed the effect of etoposide on cell viability and uptake of F-18-fluoro-deoxy- d -glucose or the glucose analog 2-[N -(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino]-2-deoxyglucose (2-NBDG) in vitro. Results:,Etoposide induced a dose-dependent cytotoxicity in HDLM-2 cells which was significantly correlated with reduced FDG uptake. However, it also significantly increased the portion of viable cells which did not take up 2-NBDG. Interestingly, etoposide-induced cytotoxicity was mainly mediated via caspase-dependent mechanisms, whereas the cell death induced by deprivation of glucose was mediated via caspase-independent mechanisms. Conclusion:,Etoposide-mediated reduction of glucose uptake by Hodgkin's lymphoma cells is mainly caused by cell death. In a small fraction of viable cells, etoposide might downregulate glucose transporters and/or hexokinase activity and by that inhibit glucose uptake. This, however, might not lead to false-negative results of response evaluation in Hodgkin's lymphoma patients after chemotherapy, because inhibition of glucose uptake itself seems to be a strong inducer of cell death. Altogether, this study provides important in vitro evidence to clarify the mechanisms by which FDG-PET monitors the effect of anti-cancer treatment in Hodgkin's lymphoma patients. [source] Inhibition of cell proliferation and glucose uptake in human laryngeal carcinoma cells by antisense oligonucleotides against glucose transporter-1HEAD & NECK: JOURNAL FOR THE SCIENCES & SPECIALTIES OF THE HEAD AND NECK, Issue 12 2009Shui-Hong Zhou PhD Abstract Background. Malignant cells show increased glucose uptake in vitro and in vivo, which is thought to be mediated by glucose transporters. In this study, we investigated the effect of plasmid-derived antisense RNA against the Glut-l gene on proliferation and glucose uptake in laryngeal carcinoma Hep-2 cells. Methods. The expression plasmids pcDNA3.1(+)-Glut-1 and pcDNA3.1(+)-anti Glut-1 were constructed. The MTT method was used to assess cell growth inhibition. The expression of Glut-1 mRNA and protein was detected by reverse transcriptase-polymerase chain reaction and Western blotting, respectively. Results. After transfection, Glut-1 AS clearly inhibited glucose uptake and cell growth in Hep-2 cells, and we observed a decrease in the expression of Glut-1 mRNA and protein in Hep-2 cells. Conclusions. Glut-1 AS decreases glucose uptake and inhibits the proliferation of Hep-2 cells. © 2009 Wiley Periodicals, Inc. Head Neck, 2009 [source] Tumor microenvironment in head and neck squamous cell carcinomas: Predictive value and clinical relevance of hypoxic markers.HEAD & NECK: JOURNAL FOR THE SCIENCES & SPECIALTIES OF THE HEAD AND NECK, Issue 6 2007A review Abstract Background. Hypoxia and tumor cell proliferation are important factors determining the treatment response of squamous cell carcinomas of the head and neck. Successful approaches have been developed to counteract these resistance mechanisms although usually at the cost of increased short- and long-term side effects. To provide the best attainable quality of life for individual patients and the head and neck cancer patient population as a whole, it is of increasing importance that tools be developed that allow a better selection of patients for these intensified treatments. Methods. A literature review was performed with special focus on the predictive value and clinical relevance of endogenous hypoxia-related markers. Results. New methods for qualitative and quantitative assessment of functional microenvironmental parameters such as hypoxia, proliferation, and vasculature have identified several candidate markers for future use in predictive assays. Hypoxia-related markers include hypoxia inducible factor (HIF)-1,, carbonic anhydrase IX, glucose transporters, erythropoietin receptor, osteopontin, and others. Although several of these markers and combinations of markers are associated with treatment outcome, their clinical value as predictive factors remains to be established. Conclusions: A number of markers and marker profiles have emerged that may have potential as a predictive assay. Validation of these candidate assays requires testing in prospective trials comparing standard treatment against experimental treatments targeting the related microregional constituent. © 2007 Wiley Periodicals, Inc. Head Neck, 2007 [source] | ||||||||||||||||||||||||||||