Exploring the whereabouts of GLUT4 in skeletal muscle (review)

DEFF Research Database (Denmark)

Ploug, Thorkil; Ralston, Evelyn

2002-01-01

related to GLUT4 storage compartments, trafficking to the surface membrane, and nature of the intracellular pools, have kept many groups busy for the past 20 years. Yet, one of the main questions in the field remains the universality of GLUT4 features. Can one extrapolate work done on fat cells to muscle......The glucose transporter GLUT4 is expressed in muscle, fat cells, brain and kidney. In contrast to other glucose transporters, GLUT4 in unstimulated cells is mostly intracellular. Stimuli such as insulin and muscle contractions then cause the translocation of GLUT4 to the cell surface. Questions...

GLUT4 in the endocrine pancreas--indicating an impact in pancreatic islet cell physiology?

Science.gov (United States)

Bähr, I; Bazwinsky-Wutschke, I; Wolgast, S; Hofmann, K; Streck, S; Mühlbauer, E; Wedekind, D; Peschke, E

2012-06-01

The glucose transporter GLUT4 is well known to facilitate the transport of blood glucose into insulin-sensitive muscle and adipose tissue. In this study, molecular, immunohistochemical, and Western blot investigations revealed evidence that GLUT4 is also located in the mouse, rat, and human endocrine pancreas. In addition, high glucose decreased and insulin elevated the GLUT4 expression in pancreatic α-cells. In contrast, high glucose increased GLUT4 expression, whereas insulin led to a reduced expression level of the glucose transporter in pancreatic β-cells. In vivo experiments showed that in pancreatic tissue of type 2 diabetic rats as well as type 2 diabetic patients, the GLUT4 expression is significantly increased compared to the nondiabetic control group. Furthermore, type 1 diabetic rats exhibited reduced GLUT4 transcript levels in pancreatic tissue, whereas insulin treatment of type 1 diabetic animals enhanced the GLUT4 expression back to control levels. These data provide evidence for the existence of GLUT4 in the endocrine pancreas and indicate a physiological relevance of this glucose transporter as well as characteristic changes in diabetic disease. © Georg Thieme Verlag KG Stuttgart · New York.

GLUT-1 expression and response to chemoradiotherapy in rectal cancer.

LENUS (Irish Health Repository)

Brophy, Sarah

2009-12-15

Preoperative chemoradiotherapy is used in locally advanced rectal cancer to reduce local recurrence and improve operability, however a proportion of tumors do not undergo significant regression. Identification of predictive markers of response to chemoradiotherapy would improve patient selection and may allow response modification by targeting of specific pathways. The aim of this study was to determine whether expression of glucose transporter-1 (GLUT-1) and p53 in pretreatment rectal cancer biopsies was predictive of tumor response to chemoradiotherapy. Immunohistochemical staining for GLUT-1 and p53 was performed on 69 pretreatment biopsies and compared to tumor response in the resected specimen as determined by the tumor regression grade (TRG) scoring system. GLUT-1 expression was significantly associated with reduced response to chemoradiotherapy and increasing GLUT expression correlated with poorer response (p=0.02). GLUT-1 negative tumors had a 70% probability of good response (TRG3\\/4) compared to a 31% probability of good response in GLUT-1 positive tumors. GLUT-1 may be a useful predictive marker of response to chemoradiotherapy in rectal cancer.

Insulin regulates Glut4 confinement in plasma membrane clusters in adipose cells.

Science.gov (United States)

Lizunov, Vladimir A; Stenkula, Karin; Troy, Aaron; Cushman, Samuel W; Zimmerberg, Joshua

2013-01-01

Insulin-stimulated delivery of glucose transporter-4 (GLUT4) to the plasma membrane (PM) is the hallmark of glucose metabolism. In this study we examined insulin's effects on GLUT4 organization in PM of adipose cells by direct microscopic observation of single monomers tagged with photoswitchable fluorescent protein. In the basal state, after exocytotic delivery only a fraction of GLUT4 is dispersed into the PM as monomers, while most of the GLUT4 stays at the site of fusion and forms elongated clusters (60-240 nm). GLUT4 monomers outside clusters diffuse freely and do not aggregate with other monomers. In contrast, GLUT4 molecule collision with an existing cluster can lead to immediate confinement and association with that cluster. Insulin has three effects: it shifts the fraction of dispersed GLUT4 upon delivery, it augments the dissociation of GLUT4 monomers from clusters ∼3-fold and it decreases the rate of endocytic uptake. All together these three effects of insulin shift most of the PM GLUT4 from clustered to dispersed states. GLUT4 confinement in clusters represents a novel kinetic mechanism for insulin regulation of glucose homeostasis.

Insulin regulates Glut4 confinement in plasma membrane clusters in adipose cells.

Directory of Open Access Journals (Sweden)

Vladimir A Lizunov

Full Text Available Insulin-stimulated delivery of glucose transporter-4 (GLUT4 to the plasma membrane (PM is the hallmark of glucose metabolism. In this study we examined insulin's effects on GLUT4 organization in PM of adipose cells by direct microscopic observation of single monomers tagged with photoswitchable fluorescent protein. In the basal state, after exocytotic delivery only a fraction of GLUT4 is dispersed into the PM as monomers, while most of the GLUT4 stays at the site of fusion and forms elongated clusters (60-240 nm. GLUT4 monomers outside clusters diffuse freely and do not aggregate with other monomers. In contrast, GLUT4 molecule collision with an existing cluster can lead to immediate confinement and association with that cluster. Insulin has three effects: it shifts the fraction of dispersed GLUT4 upon delivery, it augments the dissociation of GLUT4 monomers from clusters ∼3-fold and it decreases the rate of endocytic uptake. All together these three effects of insulin shift most of the PM GLUT4 from clustered to dispersed states. GLUT4 confinement in clusters represents a novel kinetic mechanism for insulin regulation of glucose homeostasis.

The GLUT4 density in slow fibres is not increased in athletes. How does training increase the GLUT4 pool originating from slow fibres?

DEFF Research Database (Denmark)

Gaster, M; Franch, J; Beck-Nielsen, H

2001-01-01

% of the fraction in the control group. Thus, GLUT4 originating from slow-twitch fibres was increased by 30% (Pincreases slow-twitch fibre GLUT4 expression by means of an elevated slow-twitch fibre mass in human skeletal muscle.......The influence of training on GLUT4 expression in slow- and fast-twitch skeletal muscle fibres was studied in male endurance-trained athletes and control subjects. The trained state was ensured by elevated maximal oxygen uptake (29%), as well as citrate synthase (60%) and 3-hydroxy......-acyl-CoA dehydrogenase (38%) activities in muscle biopsy samples of the vastus lateralis. GLUT4 densities in slow- and fast-twitch fibres were measured by the use of a newly developed, sensitive method combining immunohistochemistry with morphometry, and no effect of training was found. GLUT4 density was higher in slow...

Expressions of IGF-1, ERK, GLUT4, IRS-1 in metabolic syndrome complicated with colorectal cancer and their associations with the clinical characteristics of CRC.

Science.gov (United States)

Hu, Jianxia; Liu, Xiaoyi; Chi, Jingwei; Che, Kui; Feng, Yan; Zhao, Shihua; Wang, Zhongchao; Wang, Yangang

2018-01-01

Epidemiological data have revealed that colorectal cancer (CRC) risk is increased in patients with Metabolic syndrome. To explore the expressions of IGF-1, ERK, GLUT4, IRS-1 in MS patients with CRC and their associations with the clinical characteristics of CRC. We investigated the expressions of IGF-1, ERK, GLUT4 and IRS-1 in greater omental adipose tissues of 168 MS patients with/without CRC, 85 CRC patients without MS and 98 healthy controls by RT-PCR, and analyzed the relationships between their expressions and clinical characteristics of CRC. The expression levels of IGF-1 and ERK in MS patients with/without CRC were higher while the expression levels of GLUT4 were lower compared with CRC patients without MS and healthy controls (PCRC were higher while expression levels of GLUT4 were lower compared to MS patients without CRC (PCRC, including tumor size, distant metastasis and advanced stages (III/IV) (PCRC.

Expression, purification, and functional characterization of the insulin-responsive facilitative glucose transporter GLUT4.

Science.gov (United States)

Kraft, Thomas E; Hresko, Richard C; Hruz, Paul W

2015-12-01

The insulin-responsive facilitative glucose transporter GLUT4 is of fundamental importance for maintenance of glucose homeostasis. Despite intensive effort, the ability to express and purify sufficient quantities of structurally and functionally intact protein for biophysical analysis has previously been exceedingly difficult. We report here the development of novel methods to express, purify, and functionally reconstitute GLUT4 into detergent micelles and proteoliposomes. Rat GLUT4 containing FLAG and His tags at the amino and carboxy termini, respectively, was engineered and stably transfected into HEK-293 cells. Overexpression in suspension culture yielded over 1.5 mg of protein per liter of culture. Systematic screening of detergent solubilized GLUT4-GFP fusion protein via fluorescent-detection size exclusion chromatography identified lauryl maltose neopentyl glycol (LMNG) as highly effective for isolating monomeric GLUT4 micelles. Preservation of structural integrity and ligand binding was demonstrated via quenching of tryptophan fluorescence and competition of ATB-BMPA photolabeling by cytochalasin B. GLUT4 was reconstituted into lipid nanodiscs and proper folding was confirmed. Reconstitution of purified GLUT4 with amphipol A8-35 stabilized the transporter at elevated temperatures for extended periods of time. Functional activity of purified GLUT4 was confirmed by reconstitution of LMNG-purified GLUT4 into proteoliposomes and measurement of saturable uptake of D-glucose over L-glucose. Taken together, these data validate the development of an efficient means to generate milligram quantities of stable and functionally intact GLUT4 that is suitable for a wide array of biochemical and biophysical analyses. © 2015 The Protein Society.

Analysis of GLUT-1, GLUT-3, and angiogenic index in syndromic and non-syndromic keratocystic odontogenic tumors

Directory of Open Access Journals (Sweden)

Rafaella Bastos LEITE

2017-04-01

Full Text Available Abstract The aim of this study was to evaluate the immunoexpression of glucose transporters 1 (GLUT-1 and 3 (GLUT-3 in keratocystic odontogenic tumors associated with Gorlin syndrome (SKOTs and non-syndromic keratocystic odontogenic tumors (NSKOTs, and to establish correlations with the angiogenic index. Seventeen primary NSKOTs, seven recurrent NSKOTs, and 17 SKOTs were selected for the study. The percentage of immunopositive cells for GLUT-1 and GLUT-3 in the epithelial component of the tumors was assessed. The angiogenic index was determined by microvessel count. The results were analyzed statistically using the nonparametric Kruskal-Wallis test and Spearman’s correlation test. High epithelial immunoexpression of GLUT-1 was observed in most tumors (p = 0.360. There was a higher frequency of negative cases for GLUT-3 in all groups. The few GLUT-3-positive tumors exhibited low expression of this protein in epithelial cells. No significant difference in the angiogenic index was observed between groups (p = 0.778. GLUT-1 expression did not correlate significantly with the angiogenic index (p > 0.05. The results suggest that the more aggressive biological behavior of SKOTs when compared to NSKOTs may not be related to GLUT-1 or GLUT-3 expression. GLUT-1 may play an important role in glucose uptake by epithelial cells of KOTs and this process is unlikely related to the angiogenic index. GLUT-1 could be a potential target for future development of therapeutic strategies for KOTs.

The effect of intensive insulin therapy on the insulin-regulatable glucose transporter (GLUT4) expression in skeletal muscle in type 1 diabetes

DEFF Research Database (Denmark)

Andersen, P H; Vestergaard, H; Lund, S

1993-01-01

h given to patients with Type 1 diabetes in poor metabolic control was associated with an adaptive regulation of GLUT4 mRNA and protein levels in vastus lateralis muscle. Nine Type 1 diabetic patients with a mean HbA1c of 10.3% were included in the protocol. After intensified treatment with soluble.......54). These results suggest, that in spite of evidence that high insulin levels affect GLUT4 expression in muscle, changes in serum insulin within the physiological range do not play a major role in the short-term regulation of GLUT4 expression in Type 1 diabetic patients....

Near-critical GLUT1 and Neurodegeneration.

Science.gov (United States)

Barros, L Felipe; San Martín, Alejandro; Ruminot, Ivan; Sandoval, Pamela Y; Fernández-Moncada, Ignacio; Baeza-Lehnert, Felipe; Arce-Molina, Robinson; Contreras-Baeza, Yasna; Cortés-Molina, Francisca; Galaz, Alex; Alegría, Karin

2017-11-01

Recent articles have drawn renewed attention to the housekeeping glucose transporter GLUT1 and its possible involvement in neurodegenerative diseases. Here we provide an updated analysis of brain glucose transport and the cellular mechanisms involved in its acute modulation during synaptic activity. We discuss how the architecture of the blood-brain barrier and the low concentration of glucose within neurons combine to make endothelial/glial GLUT1 the master controller of neuronal glucose utilization, while the regulatory role of the neuronal glucose transporter GLUT3 emerges as secondary. The near-critical condition of glucose dynamics in the brain suggests that subtle deficits in GLUT1 function or its activity-dependent control by neurons may contribute to neurodegeneration. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Dual role for myosin II in GLUT4-mediated glucose uptake in 3T3-L1 adipocytes

International Nuclear Information System (INIS)

Fulcher, F. Kent; Smith, Bethany T.; Russ, Misty; Patel, Yashomati M.

2008-01-01

Insulin-stimulated glucose uptake requires the activation of several signaling pathways to mediate the translocation and fusion of GLUT4 vesicles to the plasma membrane. Our previous studies demonstrated that GLUT4-mediated glucose uptake is a myosin II-dependent process in adipocytes. The experiments described in this report are the first to show a dual role for the myosin IIA isoform specifically in regulating insulin-stimulated glucose uptake in adipocytes. We demonstrate that inhibition of MLCK but not RhoK results in impaired insulin-stimulated glucose uptake. Furthermore, our studies show that insulin specifically stimulates the phosphorylation of the RLC associated with the myosin IIA isoform via MLCK. In time course experiments, we determined that GLUT4 translocates to the plasma membrane prior to myosin IIA recruitment. We further show that recruitment of myosin IIA to the plasma membrane requires that myosin IIA be activated via phosphorylation of the RLC by MLCK. Our findings also reveal that myosin II is required for proper GLUT4-vesicle fusion at the plasma membrane. We show that once at the plasma membrane, myosin II is involved in regulating the intrinsic activity of GLUT4 after insulin stimulation. Collectively, our results are the first to reveal that myosin IIA plays a critical role in mediating insulin-stimulated glucose uptake in 3T3-LI adipocytes, via both GLUT4 vesicle fusion at the plasma membrane and GLUT4 activity

Infection of CD4+ T lymphocytes by the human T cell leukemia virus type 1 is mediated by the glucose transporter GLUT-1: Evidence using antibodies specific to the receptor's large extracellular domain

International Nuclear Information System (INIS)

Jin, Qingwen; Agrawal, Lokesh; VanHorn-Ali, Zainab; Alkhatib, Ghalib

2006-01-01

To analyze HTLV-1 cytotropism, we developed a highly sensitive vaccinia virus-based assay measuring activation of a reporter gene upon fusion of two distinct cell populations. We used this system in a functional cDNA screening to isolate and confirm that the glucose transporter protein 1 (GLUT-1) is a receptor for HTLV-1. GLUT-1 is a ubiquitously expressed plasma membrane glycoprotein with 12 transmembrane domains and 6 extracellular loops (ECL). We demonstrate for the first time that peptide antibodies (GLUT-IgY) raised in chicken to the large extracellular loop (ECL1) detect GLUT-1 at the cell surface and inhibit envelope (Env)-mediated fusion and infection. Efficient GLUT-IgY staining was detected with peripheral blood CD4 + lymphocytes purified by positive selection. Further, GLUT-IgY caused efficient inhibition of Env-mediated fusion and infection of CD4 + T and significantly lower inhibition of CD8 + T lymphocytes. The specificity of GLUT-IgY antibodies to GLUT-1 was demonstrated by ECL1 peptide competition studies. Grafting ECL1 of GLUT-1 onto the receptor-negative GLUT-3 conferred significant receptor activity. In contrast, grafting ECL1 of GLUT-3 onto GLUT-1 resulted in a significant loss of the receptor activity. The ECL1-mediated receptor activity was efficiently blocked with four different human monoclonal antibody (HMab) to HTLV-1 Env. The ECL1-derived peptide blocked HTLV-1 Env-mediated fusion with several nonhuman mammalian cell lines. The results demonstrate the utilization of cell surface GLUT-1 in HTLV-1 infection of CD4 + T lymphocytes and implicate a critical role for the ECL1 region in viral tropism

Myosin IIA participates in docking of Glut4 storage vesicles with the plasma membrane in 3T3-L1 adipocytes

International Nuclear Information System (INIS)

Chung, Le Thi Kim; Hosaka, Toshio; Harada, Nagakatsu; Jambaldorj, Bayasgalan; Fukunaga, Keiko; Nishiwaki, Yuka; Teshigawara, Kiyoshi; Sakai, Tohru; Nakaya, Yutaka; Funaki, Makoto

2010-01-01

In adipocytes and myocytes, insulin stimulation translocates glucose transporter 4 (Glut4) storage vesicles (GSVs) from their intracellular storage sites to the plasma membrane (PM) where they dock with the PM. Then, Glut4 is inserted into the PM and initiates glucose uptake into these cells. Previous studies using chemical inhibitors demonstrated that myosin II participates in fusion of GSVs and the PM and increase in the intrinsic activity of Glut4. In this study, the effect of myosin IIA on GSV trafficking was examined by knocking down myosin IIA expression. Myosin IIA knockdown decreased both glucose uptake and exposures of myc-tagged Glut4 to the cell surface in insulin-stimulated cells, but did not affect insulin signal transduction. Interestingly, myosin IIA knockdown failed to decrease insulin-dependent trafficking of Glut4 to the PM. Moreover, in myosin IIA knockdown cells, insulin-stimulated binding of GSV SNARE protein, vesicle-associated membrane protein 2 (VAMP2) to PM SNARE protein, syntaxin 4 was inhibited. These data suggest that myosin IIA plays a role in insulin-stimulated docking of GSVs to the PM in 3T3-L1 adipocytes through SNARE complex formation.

Expression of GLUT1 in stratified squamous epithelia and oral carcinoma from humans and rats

DEFF Research Database (Denmark)

Voldstedlund, M; Dabelsteen, Erik

1997-01-01

mucosa from rat and man, and a human oral carcinoma by indirect immunofluorescence microscopy. The results showed that GLUT1 was expressed in the basal and parabasal layers of the different stratified squamous epithelia, with some variations between keratinized and non-keratinized subtypes. GLUT1...... was also expressed in ductal- and myoepithelial cells of minor salivary glands and perineural sheath located in the lamina propra, and furthermore in the cells of an oral carcinoma. GLUT4 was not expressed in any of the tissues examined. This distribution of GLUT1 does not fit with the idea of GLUT1......Most cells express facilitative glucose transporters. Four isoforms (GLUT1-4) transporting D-glucose across the plasma membrane show a specific tissue distribution, which is the basis for tissue-specific patterns in glucose metabolism. GLUT1 is expressed at high levels in tissue barriers...

Rac1 governs exercise‐stimulated glucose uptake in skeletal muscle through regulation of GLUT4 translocation in mice

Science.gov (United States)

Nielsen, Ida L.; Kleinert, Maximilian; Møller, Lisbeth L. V.; Ploug, Thorkil; Schjerling, Peter; Bilan, Philip J.; Klip, Amira; Jensen, Thomas E.; Richter, Erik A.

2016-01-01

Key point Exercise increases skeletal muscle energy turnover and one of the important substrates for the working muscle is glucose taken up from the blood.The GTPase Rac1 can be activated by muscle contraction and has been found to be necessary for insulin‐stimulated glucose uptake, although its role in exercise‐stimulated glucose uptake is unknown.We show that Rac1 regulates the translocation of the glucose transporter GLUT4 to the plasma membrane in skeletal muscle during exercise.We find that Rac1 knockout mice display significantly reduced glucose uptake in skeletal muscle during exercise. Abstract Exercise increases skeletal muscle energy turnover and one of the important substrates for the working muscle is glucose taken up from the blood. Despite extensive efforts, the signalling mechanisms vital for glucose uptake during exercise are not yet fully understood, although the GTPase Rac1 is a candidate molecule. The present study investigated the role of Rac1 in muscle glucose uptake and substrate utilization during treadmill exercise in mice in vivo. Exercise‐induced uptake of radiolabelled 2‐deoxyglucose at 65% of maximum running capacity was blocked in soleus muscle and decreased by 80% and 60% in gastrocnemius and tibialis anterior muscles, respectively, in muscle‐specific inducible Rac1 knockout (mKO) mice compared to wild‐type littermates. By developing an assay to quantify endogenous GLUT4 translocation, we observed that GLUT4 content at the sarcolemma in response to exercise was reduced in Rac1 mKO muscle. Our findings implicate Rac1 as a regulatory element critical for controlling glucose uptake during exercise via regulation of GLUT4 translocation. PMID:27061726

Arsenite stimulated glucose transport in 3T3-L1 adipocytes involves both Glut4 translocation and p38 MAPK activity

NARCIS (Netherlands)

Bazuine, Merlijn; Ouwens, D. Margriet; Gomes de Mesquita, Daan S.; Maassen, J. Antonie

2003-01-01

The protein-modifying agent arsenite stimulates glucose uptake in 3T3-L1 adipocytes. In the current study we have analysed the signalling pathways that contribute to this response. By subcellular fractionation we observed that arsenite, like insulin, induces translocation of the GLUT1 and GLUT4

Expression of Glut-1 and Glut-3 in untreated oral squamous cell carcinoma compared with FDG accumulation in a PET study

International Nuclear Information System (INIS)

Tian, Mei; Endo, Keigo; Zhang, Hong; Nakasone, Yoshiki; Mogi, Kenji

2004-01-01

Increased expression of glucose transporter-1 (Glut-1) and glucose transporter-3 (Glut-3) has been reported in many human cancers. The mechanism of glucose entry into oral squamous cell carcinoma (OSCC) remains unclear. In this study we investigated, in untreated human OSCC, the relationship between tumour fluorine-18 fluoro-2-deoxy-d-glucose (FDG) accumulation and the expression of Glut-1 and Glut-3, as well as the association between the expression of Glut-1 and of Glut-3. All patients underwent FDG positron emission tomography (PET) pre-operatively. Standardised uptake values (SUVs) were used for evaluation of tumour FDG uptake. Final diagnoses were established by histology. Immunohistochemical staining results were evaluated according to the percentage (%) of positive area, intensity and staining score. Tumour sections were stained by immunohistochemistry for Glut-1 and Glut-3. Glut-1 immunostaining revealed that 18 (94.7%) of the 19 tumours stained positively, while Glut-3 immunostaining yielded positive findings for 16 (84.2%) tumours. Overall, a relatively low level of agreement (36.8%) in the staining score was observed between Glut-1 and Glut-3 expression. No relationship was found between the staining pattern and tumour differentiation or T grade classification in either Glut-1 or Glut-3 immunostaining. Furthermore, no relationship was found between increased FDG SUV and tumour differentiation, but the former did correlate with T grade. In conclusion, high FDG uptake values were seen in OSCC with overexpression of Glut-1 and Glut-3. However, no significant correlation was found between FDG SUV and Glut-1 or Glut-3 expression. (orig.)

Photoactivation of GLUT4 translocation promotes glucose uptake via PI3-K/Akt2 signaling in 3T3-L1 adipocytes

Directory of Open Access Journals (Sweden)

Lei Huang

2014-05-01

Full Text Available Insulin resistance is a hallmark of the metabolic syndrome and type 2 diabetes. Dysfunction of PI-3K/Akt signaling was involved in insulin resistance. Glucose transporter 4 (GLUT4 is a key factor for glucose uptake in muscle and adipose tissues, which is closely regulated by PI-3K/Akt signaling in response to insulin treatment. Low-power laser irradiation (LPLI has been shown to regulate various physiological processes and induce the synthesis or release of multiple molecules such as growth factors, which (especially red and near infrared light is mainly through the activation of mitochondrial respiratory chain and the initiation of intracellular signaling pathways. Nevertheless, it is unclear whether LPLI could promote glucose uptake through activation of PI-3K/Akt/GLUT4 signaling in 3T3L-1 adipocytes. In this study, we investigated how LPLI promoted glucose uptake through activation of PI-3K/Akt/GLUT4 signaling pathway. Here, we showed that GLUT4 was localized to the Golgi apparatus and translocated from cytoplasm to cytomembrane upon LPLI treatment in 3T3L-1 adipocytes, which enhanced glucose uptake. Moreover, we found that glucose uptake was mediated by the PI3-K/Akt2 signaling, but not Akt1 upon LPLI treatment with Akt isoforms gene silence and PI3-K/Akt inhibitors. Collectively, our results indicate that PI3-K/Akt2/GLUT4 signaling act as the key regulators for improvement of glucose uptake under LPLI treatment in 3T3L-1 adipocytes. More importantly, our findings suggest that activation of PI3-K/Akt2/GLUT4 signaling by LPLI may provide guidance in practical applications for promotion of glucose uptake in insulin-resistant adipose tissue.

Adolescents with clinical type 1 diabetes display reduced red blood cell glucose transporter isoform 1 (GLUT1).

Science.gov (United States)

Garg, Meena; Thamotharan, Manikkavasagar; Becker, Dorothy J; Devaskar, Sherin U

2014-11-01

Type 1 diabetic (T1D) adolescent children on insulin therapy suffer episodes of both hyper- and hypoglycemic episodes. Glucose transporter isoform GLUT1 expressed in blood-brain barrier (BBB) and red blood cells (RBC) compensates for perturbed circulating glucose toward protecting the supply to brain and RBCs. We hypothesized that RBC-GLUT1 concentration, as a surrogate for BBB-GLUT1, is altered in T1D children. To test this hypothesis, we measured RBC-GLUT1 by enzyme-linked immunosorbent assay (ELISA) in T1D children (n = 72; mean age 15.3 ± 0.2 yr) and control children (CON; n = 11; mean age 15.6 ± 0.9 yr) after 12 h of euglycemia and during a hyperinsulinemic-hypoglycemic clamp with a nadir blood glucose of ~3.3 mmol/L for 90 min (clamp I) or ~3 mmol/L for 45 min (clamp II). Reduced baseline RBC-GLUT1 was observed in T1D (2.4 ± 0.17 ng/ng membrane protein); vs. CON (4.2 ± 0.61 ng/ng protein) (p < 0.0001). Additionally, baseline RBC-GLUT1 in T1D negatively correlated with hemoglobin A1c (HbA1c) (R = -0.23, p < 0.05) but not in CON (R = 0.06, p < 0.9). Acute decline in serum glucose to 3.3 mmol/L (90 min) or 3 mmol/L (45 min) did not change baseline RBC-GLUT1 in T1D or CON children. We conclude that reduced RBC-GLUT1 encountered in T1D, with no ability to compensate by increasing during acute hypoglycemia over the durations examined, may demonstrate a vulnerability of impaired RBC glucose transport (serving as a surrogate for BBB), especially in those with the worst control. We speculate that this may contribute to the perturbed cognition seen in T1D adolescents. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

A steady state analysis indicates that negative feedback regulation of PTP1B by Akt elicits bistability in insulin-stimulated GLUT4 translocation

Directory of Open Access Journals (Sweden)

Giri Lopamudra

2004-08-01

Full Text Available Abstract Background The phenomenon of switch-like response to graded input signal is the theme involved in various signaling pathways in living systems. Positive feedback loops or double negative feedback loops embedded with nonlinearity exhibit these switch-like bistable responses. Such feedback regulations exist in insulin signaling pathway as well. Methods In the current manuscript, a steady state analysis of the metabolic insulin-signaling pathway is presented. The threshold concentration of insulin required for glucose transporter GLUT4 translocation was studied with variation in system parameters and component concentrations. The dose response curves of GLUT4 translocation at various concentration of insulin obtained by steady state analysis were quantified in-terms of half saturation constant. Results We show that, insulin-stimulated GLUT4 translocation can operate as a bistable switch, which ensures that GLUT4 settles between two discrete, but mutually exclusive stable steady states. The threshold concentration of insulin required for GLUT4 translocation changes with variation in system parameters and component concentrations, thus providing insights into possible pathological conditions. Conclusion A steady state analysis indicates that negative feedback regulation of phosphatase PTP1B by Akt elicits bistability in insulin-stimulated GLUT4 translocation. The threshold concentration of insulin required for GLUT4 translocation and the corresponding bistable response at different system parameters and component concentrations was compared with reported experimental observations on specific defects in regulation of the system.

Refractory absence epilepsy associated with GLUT-1 deficiency syndrome.

LENUS (Irish Health Repository)

Byrne, Susan

2011-05-01

GLUT-1 deficiency syndrome (GLUT-1 DS) is a disorder of cerebral glucose transport associated with early infantile epilepsy and microcephaly. We report two boys who presented with refractory absence epilepsy associated with hypoglycorrhachia, both of whom have genetically confirmed GLUT-1 DS. We propose that these children serve to expand the phenotype of GLUT-1 DS and suggest that this condition should be considered as a cause of refractory absence seizures in childhood.

Autosomal dominant transmission of GLUT1 deficiency.

NARCIS (Netherlands)

Klepper, J.; Willemsen, M.A.A.P.; Verrips, A.; Guertsen, E.; Herrmann, R.; Kutzick, C.; Florcken, A.; Voit, T.

2001-01-01

GLUT1 deficiency is caused by a defect in the facilitative glucose transporter GLUT1. Impaired glucose transport across brain tissue barriers is reflected by hypoglycorrhachia and results in an epileptic encephalopathy with developmental delay and motor disorders. Recently heterozygous mutations in

Super-resolution microscopy reveals the insulin-resistance-regulated reorganization of GLUT4 on plasma membranes.

Science.gov (United States)

Gao, Lan; Chen, Junling; Gao, Jing; Wang, Hongda; Xiong, Wenyong

2017-01-15

GLUT4 (also known as SLC2A4) is essential for glucose uptake in skeletal muscles and adipocytes, which play central roles in whole-body glucose metabolism. Here, using direct stochastic optical reconstruction microscopy (dSTORM) to investigate the characteristics of plasma-membrane-fused GLUT4 at the single-molecule level, we have demonstrated that insulin and insulin resistance regulate the spatial organization of GLUT4 in adipocytes. Stimulation with insulin shifted the balance of GLUT4 on the plasma membrane toward a more dispersed configuration. In contrast, insulin resistance induced a more clustered distribution of GLUT4 and increased the mean number of molecules per cluster. Furthermore, our data demonstrate that the F 5 QQI motif and lipid rafts mediate the maintenance of GLUT4 clusters on the plasma membrane. Mutation of F 5 QQI (F 5 QQA-GLUT4) induced a more clustered distribution of GLUT4; moreover, destruction of lipid rafts in adipocytes expressing F 5 QQA-GLUT4 dramatically decreased the percentage of large clusters and the mean number of molecules per cluster. In conclusion, our data clarify the effects of insulin stimulation or insulin resistance on GLUT4 reorganization on the plasma membrane and reveal new pathogenic mechanisms of insulin resistance. © 2017. Published by The Company of Biologists Ltd.

Anorexia and Impaired Glucose Metabolism in Mice With Hypothalamic Ablation of Glut4 Neurons

OpenAIRE

Ren, Hongxia; Lu, Taylor Y.; McGraw, Timothy E.; Accili, Domenico

2014-01-01

The central nervous system (CNS) uses glucose independent of insulin. Nonetheless, insulin receptors and insulin-responsive glucose transporters (Glut4) often colocalize in neurons (Glut4 neurons) in anatomically and functionally distinct areas of the CNS. The apparent heterogeneity of Glut4 neurons has thus far thwarted attempts to understand their function. To answer this question, we used Cre-dependent, diphtheria toxin?mediated cell ablation to selectively remove basal hypothalamic Glut4 ...

Demonstration of differential quantitative requirements for NSF among multiple vesicle fusion pathways of GLUT4 using a dominant-negative ATPase-deficient NSF

International Nuclear Information System (INIS)

Chen Xiaoli; Matsumoto, Hideko; Hinck, Cynthia S.; Al-Hasani, Hadi; St-Denis, Jean-Francois; Whiteheart, Sidney W.; Cushman, Samuel W.

2005-01-01

In this study, we investigated the relative participation of N-ethylmaleimide-sensitive factor (NSF) in vivo in a complex multistep vesicle trafficking system, the translocation response of GLUT4 to insulin in rat adipose cells. Transfections of rat adipose cells demonstrate that over-expression of wild-type NSF has no effect on total, or basal and insulin-stimulated cell-surface expression of HA-tagged GLUT4. In contrast, a dominant-negative NSF (NSF-D1EQ) can be expressed at a low enough level that it has little effect on total HA-GLUT4, but does reduce both basal and insulin-stimulated cell-surface HA-GLUT4 by ∼50% without affecting the GLUT4 fold-translocation response to insulin. However, high expression levels of NSF-D1EQ decrease total HA-GLUT4. The inhibitory effect of NSF-D1EQ on cell-surface HA-GLUT4 is reversed when endocytosis is inhibited by co-expression of a dominant-negative dynamin (dynamin-K44A). Moreover, NSF-D1EQ does not affect cell-surface levels of constitutively recycling GLUT1 and TfR, suggesting a predominant effect of low-level NSF-D1EQ on the trafficking of GLUT4 from the endocytic recycling compared to the intracellular GLUT4-specific compartment. Thus, our data demonstrate that the multiple fusion steps in GLUT4 trafficking have differential quantitative requirements for NSF activity. This indicates that the rates of plasma and intracellular membrane fusion reactions vary, leading to differential needs for the turnover of the SNARE proteins

GLUT11, but not GLUT8 or GLUT12, is expressed in human skeletal muscle in a fibre type-specific pattern

DEFF Research Database (Denmark)

Gaster, M; Handberg, A; Schürmann, A

2004-01-01

or amyotrophic lateral sclerosis (ALS) were studied. GLUT8 and 12 immunoreactivity was below detection level in both developing and adult muscle fibres. GLUT11 immunoreactivity, however, was present in slow-twitch muscle fibres, but not in fast twitch fibres. Since, in contrast, GLUT4 was expressed in all...... exclusively in slow-twitch muscle fibres and is unaffected by physiological and pathophysiological conditions except in primary myopathy. GLUT8 and GLUT12 do not appear to be of importance in human muscle under physiological and pathophysiological conditions....... to induce GLUT8 or -12 expression. Likewise, the fibre type-dependent pattern of GLUT11 immunoreactivity was unaltered. However, some slow muscle fibres lose their GLUT11 immunoreactivity under regeneration. Our results indicate that GLUT11 immunoreactivity, in contrast to that of GLUT4, is expressed...

Severe Hypertriglyceridemia in Glut1D on Ketogenic Diet.

Science.gov (United States)

Klepper, Joerg; Leiendecker, Baerbel; Heussinger, Nicole; Lausch, Ekkehart; Bosch, Friedrich

2016-04-01

High-fat ketogenic diets are the only treatment available for Glut1 deficiency (Glut1D). Here, we describe an 8-year-old girl with classical Glut1D responsive to a 3:1 ketogenic diet and ethosuximide. After 3 years on the diet a gradual increase of blood lipids was followed by rapid, severe asymptomatic hypertriglyceridemia (1,910 mg/dL). Serum lipid apheresis was required to determine liver, renal, and pancreatic function. A combination of medium chain triglyceride-oil and a reduction of the ketogenic diet to 1:1 ratio normalized triglyceride levels within days but triggered severe myoclonic seizures requiring comedication with sultiam. Severe hypertriglyceridemia in children with Glut1D on ketogenic diets may be underdiagnosed and harmful. In contrast to congenital hypertriglyceridemias, children with Glut1D may be treated effectively by dietary adjustments alone. Georg Thieme Verlag KG Stuttgart · New York.

Abnormal subcellular distribution of GLUT4 protein in obese and insulin-treated diabetic female dogs

Directory of Open Access Journals (Sweden)

A.M. Vargas

2004-07-01

Full Text Available The GLUT4 transporter plays a key role in insulin-induced glucose uptake, which is impaired in insulin resistance. The objective of the present study was to investigate the tissue content and the subcellular distribution of GLUT4 protein in 4- to 12-year-old control, obese and insulin-treated diabetic mongrel female dogs (4 animals per group. The parametrial white adipose tissue was sampled and processed to obtain both plasma membrane and microsome subcellular fractions for GLUT4 analysis by Western blotting. There was no significant difference in glycemia and insulinemia between control and obese animals. Diabetic dogs showed hyperglycemia (369.9 ± 89.9 mg/dl. Compared to control, the plasma membrane GLUT4, reported per g tissue, was reduced by 55% (P < 0.01 in obese dogs, and increased by 30% (P < 0.05 in diabetic dogs, and the microsomal GLUT4 was increased by ~45% (P < 0.001 in both obese and diabetic animals. Considering the sum of GLUT4 measured in plasma membrane and microsome as total cellular GLUT4, percent GLUT4 present in plasma membrane was reduced by ~65% (P < 0.001 in obese compared to control and diabetic animals. Since insulin stimulates GLUT4 translocation to the plasma membrane, percent GLUT4 in plasma membrane was divided by the insulinemia at the time of tissue removal and was found to be reduced by 75% (P < 0.01 in obese compared to control dogs. We conclude that the insulin-stimulated translocation of GLUT4 to the cell surface is reduced in obese female dogs. This probably contributes to insulin resistance, which plays an important role in glucose homeostasis in dogs.

PGC-1{alpha} is required for AICAR induced expression of GLUT4 and mitochondrial proteins in mouse skeletal muscle

DEFF Research Database (Denmark)

Leick, Lotte; Fentz, Joachim; Biensø, Rasmus S

2010-01-01

We tested the hypothesis that repeated activation of AMPK induces mitochondrial and glucose membrane transporter gene/protein expression via a peroxisome proliferator activated receptor Upsilon co-activator (PGC)-1alpha dependent mechanism. Whole body PGC-1alpha knockout (KO) and littermate wild...... GLUT4, cytochrome c oxidase (COX)I and cytochrome (cyt) c protein expression ~10-40% relative to saline in white muscles of the WT mice, but not of the PGC-1alpha KO mice. In line, GLUT4 and cyt c mRNA content increased 30-60% 4h after a single AICAR injection relative to saline only in WT mice. One...... and PGC-1alpha KO mice. In conclusion, we here provide genetic evidence for a major role of PGC-1alpha in AMPK mediated regulation of mitochondrial and glucose membrane transport protein expression in skeletal muscle....

GLUT4 Mobilization Supports Energetic Demands of Active Synapses.

Science.gov (United States)

Ashrafi, Ghazaleh; Wu, Zhuhao; Farrell, Ryan J; Ryan, Timothy A

2017-02-08

The brain is highly sensitive to proper fuel availability as evidenced by the rapid decline in neuronal function during ischemic attacks and acute severe hypoglycemia. We previously showed that sustained presynaptic function requires activity-driven glycolysis. Here, we provide strong evidence that during action potential (AP) firing, nerve terminals rely on the glucose transporter GLUT4 as a glycolytic regulatory system to meet the activity-driven increase in energy demands. Activity at synapses triggers insertion of GLUT4 into the axonal plasma membrane driven by activation of the metabolic sensor AMP kinase. Furthermore, we show that genetic ablation of GLUT4 leads to an arrest of synaptic vesicle recycling during sustained AP firing, similar to what is observed during acute glucose deprivation. The reliance on this biochemical regulatory system for "exercising" synapses is reminiscent of that occurring in exercising muscle to sustain cellular function and identifies nerve terminals as critical sites of proper metabolic control. Copyright © 2017 Elsevier Inc. All rights reserved.

Anorexia and impaired glucose metabolism in mice with hypothalamic ablation of Glut4 neurons.

Science.gov (United States)

Ren, Hongxia; Lu, Taylor Y; McGraw, Timothy E; Accili, Domenico

2015-02-01

The central nervous system (CNS) uses glucose independent of insulin. Nonetheless, insulin receptors and insulin-responsive glucose transporters (Glut4) often colocalize in neurons (Glut4 neurons) in anatomically and functionally distinct areas of the CNS. The apparent heterogeneity of Glut4 neurons has thus far thwarted attempts to understand their function. To answer this question, we used Cre-dependent, diphtheria toxin-mediated cell ablation to selectively remove basal hypothalamic Glut4 neurons and investigate the resulting phenotypes. After Glut4 neuron ablation, mice demonstrate altered hormone and nutrient signaling in the CNS. Accordingly, they exhibit negative energy balance phenotype characterized by reduced food intake and increased energy expenditure, without locomotor deficits or gross neuronal abnormalities. Glut4 neuron ablation affects orexigenic melanin-concentrating hormone neurons but has limited effect on neuropeptide Y/agouti-related protein and proopiomelanocortin neurons. The food intake phenotype can be partially normalized by GABA administration, suggesting that it arises from defective GABAergic transmission. Glut4 neuron-ablated mice show peripheral metabolic defects, including fasting hyperglycemia and glucose intolerance, decreased insulin levels, and elevated hepatic gluconeogenic genes. We conclude that Glut4 neurons integrate hormonal and nutritional cues and mediate CNS actions of insulin on energy balance and peripheral metabolism. © 2015 by the American Diabetes Association. Readers may use this article as long as the work is properly cited, the use is educational and not for profit, and the work is not altered.

(+-Rutamarin as a dual inducer of both GLUT4 translocation and expression efficiently ameliorates glucose homeostasis in insulin-resistant mice.

Directory of Open Access Journals (Sweden)

Yu Zhang

Full Text Available Glucose transporter 4 (GLUT4 is a principal glucose transporter in response to insulin, and impaired translocation or decreased expression of GLUT4 is believed to be one of the major pathological features of type 2 diabetes mellitus (T2DM. Therefore, induction of GLUT4 translocation or/and expression is a promising strategy for anti-T2DM drug discovery. Here we report that the natural product (+-Rutamarin (Rut functions as an efficient dual inducer on both insulin-induced GLUT4 translocation and expression. Rut-treated 3T3-L1 adipocytes exhibit efficiently enhanced insulin-induced glucose uptake, while diet-induced obese (DIO mice based assays further confirm the Rut-induced improvement of glucose homeostasis and insulin sensitivity in vivo. Subsequent investigation of Rut acting targets indicates that as a specific protein tyrosine phosphatase 1B (PTP1B inhibitor Rut induces basal GLUT4 translocation to some extent and largely enhances insulin-induced GLUT4 translocation through PI3 kinase-AKT/PKB pathway, while as an agonist of retinoid X receptor α (RXRα, Rut potently increases GLUT4 expression. Furthermore, by using molecular modeling and crystallographic approaches, the possible binding modes of Rut to these two targets have been also determined at atomic levels. All our results have thus highlighted the potential of Rut as both a valuable lead compound for anti-T2DM drug discovery and a promising chemical probe for GLUT4 associated pathways exploration.

Autosomal recessive inheritance of GLUT1 deficiency syndrome.

NARCIS (Netherlands)

Klepper, J.; Scheffer, H.; Elsaid, M.F.; Kamsteeg, E.J.; Leferink, M.; Ben-Omran, T.

2009-01-01

GLUT1 deficiency syndrome (GLUT1DS) is understood as a monogenetic disease caused by heterozygous SLC2A1 gene mutations with autosomaldominant and sporadic transmission. We report on a six-year-old girl from an inbred Arab family with moderate global developmental delay, epilepsy, ataxia, hypotonia,

Small G proteins in insulin action: Rab and Rho families at the crossroads of signal transduction and GLUT4 vesicle traffic.

Science.gov (United States)

Ishikura, S; Koshkina, A; Klip, A

2008-01-01

Insulin stimulates glucose uptake into muscle and adipose tissues through glucose transporter 4 (GLUT4). GLUT4 cycles between the intracellular compartments and the plasma membrane. GLUT4 traffic-regulating insulin signals are largely within the insulin receptor-insulin receptor substrate-phosphatidylinositol 3-kinase (IR-IRS-PI3K) axis. In muscle cells, insulin signal bifurcates downstream of the PI3K into one arm leading to the activation of the Ser/Thr kinases Akt and atypical protein kinase C, and another leading to the activation of Rho family protein Rac1 leading to actin remodelling. Activated Akt inactivates AS160, a GTPase-activating protein for Rab family small G proteins. Here we review the roles of Rab and Rho proteins, particularly Rab substrates of AS160 and Rac1, in insulin-stimulated GLUT4 traffic. We discuss: (1) how distinct steps in GLUT4 traffic may be regulated by discrete Rab proteins, and (2) the importance of Rac1 activation in insulin-induced actin remodelling in muscle cells, a key element for the net gain in surface GLUT4.

Effect of curcumin Extract on Ttranslocation of Glut 4 in C2C12 Myotubes

Directory of Open Access Journals (Sweden)

J Zavarreza

2013-06-01

Full Text Available Introduction: Curcumin is a major phenolic compound of Curcuma longa, which has long been used in traditional Indian medicine. Recently, curcumin has been reported to have antihyperglycemic activity in animal models. However, the molecular basis of this action has not been adequatedly described. In the present study the antihyperglycemic effect of curcumin was examined using C2C12 myoblast cells. Methods: The effects of curcumin were investigated in C2C12 myotubes by treating the cells with 40 µM of curcumin for 1.5 h. C2C12 myotubes were homogenized and the subcellular fractionation was prepared using ultracentrifugation; Then protein assay was performed using Bradford method and Glut4 determination was done using SDS-PAGE. Moreover, western immunoblotting techniques were exerted for semi-quantitative measurement. Data analysis was performed via gene tools software of Gel documentation and SPSS. An ANOVA test was used to compare three groups together. Results: Comparison of Glut4 levels in C2C12 myotubes showed that myotubes which were exposed to1.5 hours of 40 µM curcunin had higher Glut4 percentages in both cytosolic and membrane fractions and Glut4 percentages were significant with a confidence interval (CI of 95% ( P<0.05 . Conclusion: The study results showed that curcumin can strongly induce the increase of Glut4 translocation in differentiated C2C12 cells, indicating its possible regulatory role in the glucose metabolism of skeletal muscle cells

Peripheral insulin resistance in ILK-depleted mice by reduction of GLUT4 expression.

Science.gov (United States)

Hatem-Vaquero, Marco; Griera, Mercedes; García-Jerez, Andrea; Luengo, Alicia; Álvarez, Julia; Rubio, José A; Calleros, Laura; Rodríguez-Puyol, Diego; Rodríguez-Puyol, Manuel; De Frutos, Sergio

2017-08-01

The development of insulin resistance is characterized by the impairment of glucose uptake mediated by glucose transporter 4 (GLUT4). Extracellular matrix changes are induced when the metabolic dysregulation is sustained. The present work was devoted to analyze the possible link between the extracellular-to-intracellular mediator integrin-linked kinase (ILK) and the peripheral tissue modification that leads to glucose homeostasis impairment. Mice with general depletion of ILK in adulthood (cKD-ILK) maintained in a chow diet exhibited increased glycemia and insulinemia concurrently with a reduction of the expression and membrane presence of GLUT4 in the insulin-sensitive peripheral tissues compared with their wild-type littermates (WT). Tolerance tests and insulin sensitivity indexes confirmed the insulin resistance in cKD-ILK, suggesting a similar stage to prediabetes in humans. Under randomly fed conditions, no differences between cKD-ILK and WT were observed in the expression of insulin receptor (IR-B) and its substrate IRS-1 expressions. The IR-B isoform phosphorylated at tyrosines 1150/1151 was increased, but the AKT phosphorylation in serine 473 was reduced in cKD-ILK tissues. Similarly, ILK-blocked myotubes reduced their GLUT4 promoter activity and GLUT4 expression levels. On the other hand, the glucose uptake capacity in response to exogenous insulin was impaired when ILK was blocked in vivo and in vitro , although IR/IRS/AKT phosphorylation states were increased but not different between groups. We conclude that ILK depletion modifies the transcription of GLUT4, which results in reduced peripheral insulin sensitivity and glucose uptake, suggesting ILK as a molecular target and a prognostic biomarker of insulin resistance. © 2017 Society for Endocrinology.

Changes in photoperiod alter Glut4 expression in skeletal muscle of C57BL/6J mice

International Nuclear Information System (INIS)

Tashiro, Ayako; Shibata, Satomi; Takai, Yusuke; Uchiwa, Tatsuhiro; Furuse, Mitsuhiro; Yasuo, Shinobu

2017-01-01

Seasonal changes in photoperiod influence body weight and metabolism in mice. Here, we examined the effect of changes in photoperiod on the expression of glucose transporter genes in the skeletal muscle and adipose tissue of C57BL/6J mice. Glut4 expression was lower in the gastrocnemius muscle of mice exposed to a short-duration day (SD) than those to a long-duration day (LD), with accompanying changes in GLUT4 protein levels. Although Glut4 expression in the mouse soleus muscle was higher under SD than under LD, GLUT4 protein levels remained unchanged. To confirm the functional significance of photoperiod-induced changes in Glut4 expression, we checked for variations in insulin sensitivity. Blood glucose levels after insulin injection remained high under SD, suggesting that the mice exposed to SD showed lower sensitivity to insulin than those exposed to LD. We also attempted to clarify the relationship between Glut4 expression and physical activity in the mice following changes in photoperiod. Locomotor activity, as detected via infrared beam sensor, was lower under SD than under LD. However, when we facilitated voluntary activity by using running wheels, the rotation of wheels was similar for both groups of mice. Although physical activity levels were enhanced due to running wheels, Glut4 expression in the gastrocnemius muscle remained unchanged. Thus, variations in photoperiod altered Glut4 expression in the mouse skeletal muscle, with subsequent changes in GLUT4 protein levels and insulin sensitivity; these effects might be independent of physical activity. - Highlights: • Glut4 expression in the gastrocnemius muscle was lowered under short photoperiod. • Insulin sensitivity was lowered under short photoperiod. • Access to running wheels did not alter Glut4 expression in the gastrocnemius muscle. • Photoperiodic changes in Glut4 expression may be independent of physical activity.

Brain GLUT4 Knockout Mice Have Impaired Glucose Tolerance, Decreased Insulin Sensitivity, and Impaired Hypoglycemic Counterregulation

Science.gov (United States)

Reno, Candace M.; Puente, Erwin C.; Sheng, Zhenyu; Daphna-Iken, Dorit; Bree, Adam J.; Routh, Vanessa H.; Kahn, Barbara B.

2017-01-01

GLUT4 in muscle and adipose tissue is important in maintaining glucose homeostasis. However, the role of insulin-responsive GLUT4 in the central nervous system has not been well characterized. To assess its importance, a selective knockout of brain GLUT4 (BG4KO) was generated by crossing Nestin-Cre mice with GLUT4-floxed mice. BG4KO mice had a 99% reduction in GLUT4 protein expression throughout the brain. Despite normal feeding and fasting glycemia, BG4KO mice were glucose intolerant, demonstrated hepatic insulin resistance, and had reduced glucose uptake in the brain. In response to hypoglycemia, BG4KO mice had impaired glucose sensing, noted by impaired epinephrine and glucagon responses and impaired c-fos activation in the hypothalamic paraventricular nucleus. Moreover, in vitro glucose sensing of glucose-inhibitory neurons from the ventromedial hypothalamus was impaired in BG4KO mice. In summary, BG4KO mice are glucose intolerant, insulin resistant, and have impaired glucose sensing, indicating a critical role for brain GLUT4 in sensing and responding to changes in blood glucose. PMID:27797912

Kinetics of contraction-induced GLUT4 translocation in skeletal muscle fibers from living mice

DEFF Research Database (Denmark)

Lauritzen, Hans Peter M. Mortensen; Galbo, Henrik; Toyoda, Taro

2010-01-01

Exercise is an important strategy for the treatment of type 2 diabetes. This is due in part to an increase in glucose transport that occurs in the working skeletal muscles. Glucose transport is regulated by GLUT4 translocation in muscle, but the molecular machinery mediating this process is poorl...... understood. The purpose of this study was to 1) use a novel imaging system to elucidate the kinetics of contraction-induced GLUT4 translocation in skeletal muscle and 2) determine the function of AMP-activated protein kinase alpha2 (AMPKalpha2) in this process.......Exercise is an important strategy for the treatment of type 2 diabetes. This is due in part to an increase in glucose transport that occurs in the working skeletal muscles. Glucose transport is regulated by GLUT4 translocation in muscle, but the molecular machinery mediating this process is poorly...

The beneficial effects of exercise in rodents are preserved after detraining: a phenomenon unrelated to GLUT4 expression

Directory of Open Access Journals (Sweden)

De Angelis Kátia

2010-10-01

Full Text Available Abstract Background Although exercise training has well-known cardiorespiratory and metabolic benefits, low compliance with exercise training programs is a fact, and the harmful effects of physical detraining regarding these adaptations usually go unnoticed. We investigated the effects of exercise detraining on blood pressure, insulin sensitivity, and GLUT4 expression in spontaneously hypertensive rats (SHR and normotensive Wistar Kyoto rats (WKY. Methods Studied animals were randomized into sedentary, trained (treadmill running/5 days a week, 60 min/day for 10 weeks, 1 week of detraining, and 2 weeks of detraining. Blood pressure (tail-cuff system, insulin sensitivity (kITT, and GLUT4 (Western blot in heart, gastrocnemius and white fat tissue were measured. Results Exercise training reduced blood pressure (19%, improved insulin sensitivity (24%, and increased GLUT4 in the heart (+34%; gastrocnemius (+36% and fat (+22% in SHR. In WKY no change in either blood pressure or insulin sensitivity were observed, but there was an increase in GLUT4 in the heart (+25%, gastrocnemius (+45% and fat (+36% induced by training. Both periods of detraining did not induce any change in neither blood pressure nor insulin sensitivity in SHR and WKY. One-week detraining reduced GLUT4 in SHR (heart: -28%; fat: -23% and WKY (heart: -19%; fat: -22%; GLUT4 in the gastrocnemius was reduced after a 2-week detraining (SHR: -35%; WKY: -25%. There was a positive correlation between GLUT4 (gastrocnemius and the maximal velocity in the exercise test (r = 0.60, p = 0.004. Conclusions The study findings show that in detraining, despite reversion of the enhanced GLUT4 expression, cardiorespiratory and metabolic beneficial effects of exercise are preserved.

Brain GLUT4 Knockout Mice Have Impaired Glucose Tolerance, Decreased Insulin Sensitivity, and Impaired Hypoglycemic Counterregulation.

Science.gov (United States)

Reno, Candace M; Puente, Erwin C; Sheng, Zhenyu; Daphna-Iken, Dorit; Bree, Adam J; Routh, Vanessa H; Kahn, Barbara B; Fisher, Simon J

2017-03-01

GLUT4 in muscle and adipose tissue is important in maintaining glucose homeostasis. However, the role of insulin-responsive GLUT4 in the central nervous system has not been well characterized. To assess its importance, a selective knockout of brain GLUT4 (BG4KO) was generated by crossing Nestin-Cre mice with GLUT4-floxed mice. BG4KO mice had a 99% reduction in GLUT4 protein expression throughout the brain. Despite normal feeding and fasting glycemia, BG4KO mice were glucose intolerant, demonstrated hepatic insulin resistance, and had reduced glucose uptake in the brain. In response to hypoglycemia, BG4KO mice had impaired glucose sensing, noted by impaired epinephrine and glucagon responses and impaired c-fos activation in the hypothalamic paraventricular nucleus. Moreover, in vitro glucose sensing of glucose-inhibitory neurons from the ventromedial hypothalamus was impaired in BG4KO mice. In summary, BG4KO mice are glucose intolerant, insulin resistant, and have impaired glucose sensing, indicating a critical role for brain GLUT4 in sensing and responding to changes in blood glucose. © 2017 by the American Diabetes Association.

Role of insulin on exercise-induced GLUT-4 protein expression and glycogen supercompensation in rat skeletal muscle.

Science.gov (United States)

Kuo, Chia-Hua; Hwang, Hyonson; Lee, Man-Cheong; Castle, Arthur L; Ivy, John L

2004-02-01

The purpose of this study was to investigate the role of insulin on skeletal muscle GLUT-4 protein expression and glycogen storage after postexercise carbohydrate supplementation. Male Sprague-Dawley rats were randomly assigned to one of six treatment groups: sedentary control (Con), Con with streptozocin (Stz/C), immediately postexercise (Ex0), Ex0 with Stz (Stz/Ex0), 5-h postexercise (Ex5), and Ex5 with Stz (Stz/Ex5). Rats were exercised by swimming (2 bouts of 3 h) and carbohydrate supplemented immediately after each exercise session by glucose intubation (1 ml of a 50% wt/vol). Stz was administered 72-h before exercise, which resulted in hyperglycemia and elimination of the insulin response to the carbohydrate supplement. GLUT-4 protein of Ex0 rats was 30% above Con in fast-twitch (FT) red and 21% above Con in FT white muscle. In Ex5, GLUT-4 protein was 52% above Con in FT red and 47% above Con in FT white muscle. Muscle glycogen in FT red and white muscle was also increased above Con in Ex5 rats. Neither GLUT-4 protein nor muscle glycogen was increased above Con in Stz/Ex0 or Stz/Ex5 rats. GLUT-4 mRNA in FT red muscle of Ex0 rats was 61% above Con but only 33% above Con in Ex5 rats. GLUT-4 mRNA in FT red muscle of Stz/C and Stz/Ex0 rats was similar but significantly elevated in Ex5/Stz rats. These results suggest that insulin is essential for the increase in GLUT-4 protein expression following postexercise carbohydrate supplementation.

GLUT4 is reduced in slow muscle fibers of type 2 diabetic patients: is insulin resistance in type 2 diabetes a slow, type 1 fiber disease?

DEFF Research Database (Denmark)

Gaster, M; Staehr, P; Beck-Nielsen, H

2001-01-01

To gain further insight into the mechanisms underlying muscle insulin resistance, the influence of obesity and type 2 diabetes on GLUT4 immunoreactivity in slow and fast skeletal muscle fibers was studied. Through a newly developed, very sensitive method using immunohistochemistry combined...... with morphometry, GLUT4 density was found to be significantly higher in slow compared with fast fibers in biopsy specimens from lean and obese subjects. In contrast, in type 2 diabetic subjects, GLUT4 density was significantly lower in slow compared with fast fibers. GLUT4 density in slow fibers from diabetic...... was reduced to 77% in the obese subjects and to 61% in type 2 diabetic patients compared with the control subjects. We propose that a reduction in the fraction of slow-twitch fibers, combined with a reduction in GLUT4 expression in slow fibers, may reduce the insulin-sensitive GLUT4 pool in type 2 diabetes...

GLUT-1 DEFICIENCY: FROM PATHOPHYSILOGY AND GENETICS TO ABROAD CLINICAL SPECTRUM

Directory of Open Access Journals (Sweden)

Arsov Todor

2016-07-01

Full Text Available The classical GLUT-1 deficiency syndrome (GLUT-1 DS, De Vivo disease was described over 2 decades ago as a metabolic encephalopathy characterized by developmental delay, secondary microcephaly paroxysmal neurological symptoms (epilepsy and movement disorders. The biochemical parameters of this disease, used in diagnosis, are low levels of glucose in the cerebrospinal fluid, normal level of glucose in the blood and consequent low ratio of cerebrospinal fluid vs. blood glucose levels (<40-45%. So far, more than 200 cases of the classical GLUT-1 DS have been described in the literature. Genetic research demonstrated that this disease is caused by mutations in SLC2A1 gene coding for GLUT-1, a transporter of glucose across the blood brain barrier. Over the last few years the clinical spectrum of GLUT-1 deficiencywas expanded to include other rare diseases such as paroxysmal exertional dyskinesia and early-onset absence epilepsy, but also some more common diseases such as idiopathic generalised epilepsy (1-2%. GLUT-1 deficiency is an important pathophysiological basis of these diseases as early diagnosis (aided by DNA mutation testing and treatment (ketogenic diet could lead to improved disease outcomes.

Exercise, GLUT4, and Skeletal Muscle Glucose Uptake

DEFF Research Database (Denmark)

Richter, Erik; Hargreaves, Mark

2013-01-01

Glucose is an important fuel for contracting muscle, and normal glucose metabolism is vital for health. Glucose enters the muscle cell via facilitated diffusion through the GLUT4 glucose transporter which translocates from intracellular storage depots to the plasma membrane and T-tubules upon...... muscle contraction. Here we discuss the current understanding of how exercise-induced muscle glucose uptake is regulated. We briefly discuss the role of glucose supply and metabolism and concentrate on GLUT4 translocation and the molecular signaling that sets this in motion during muscle contractions....... Contraction-induced molecular signaling is complex and involves a variety of signaling molecules including AMPK, Ca(2+), and NOS in the proximal part of the signaling cascade as well as GTPases, Rab, and SNARE proteins and cytoskeletal components in the distal part. While acute regulation of muscle glucose...

Kinetics of contraction-induced GLUT4 translocation in skeletal muscle fibers from living mice

DEFF Research Database (Denmark)

Lauritzen, Hans Peter M. Mortensen; Galbo, Henrik; Toyoda, Taro

2010-01-01

Exercise is an important strategy for the treatment of type 2 diabetes. This is due in part to an increase in glucose transport that occurs in the working skeletal muscles. Glucose transport is regulated by GLUT4 translocation in muscle, but the molecular machinery mediating this process is poorly...... understood. The purpose of this study was to 1) use a novel imaging system to elucidate the kinetics of contraction-induced GLUT4 translocation in skeletal muscle and 2) determine the function of AMP-activated protein kinase alpha2 (AMPKalpha2) in this process....

GLUT4 trafficking in a test tube.

Science.gov (United States)

Ramm, Georg; James, David E

2005-09-01

Insulin regulates glucose transport in muscle and fat cells by stimulating the translocation of GLUT4 from intracellular vesicles to the plasma membrane. In this issue of Cell Metabolism, Holman and colleagues reconstitute this process in vitro, providing a system that promises new breakthroughs in our understanding of this important metabolic process.

Impaired translocation of GLUT4 results in insulin resistance of atrophic soleus muscle.

Science.gov (United States)

Xu, Peng-Tao; Song, Zhen; Zhang, Wen-Cheng; Jiao, Bo; Yu, Zhi-Bin

2015-01-01

Whether or not the atrophic skeletal muscle induces insulin resistance and its mechanisms are not resolved now. The antigravity soleus muscle showed a progressive atrophy in 1-week, 2-week, and 4-week tail-suspended rats. Hyperinsulinemic-euglycemic clamp showed that the steady-state glucose infusion rate was lower in 4-week tail-suspended rats than that in the control rats. The glucose uptake rates under insulin- or contraction-stimulation were significantly decreased in 4-week unloaded soleus muscle. The key protein expressions of IRS-1, PI3K, and Akt on the insulin-dependent pathway and of AMPK, ERK, and p38 on the insulin-independent pathway were unchanged in unloaded soleus muscle. The unchanged phosphorylation of Akt and p38 suggested that the activity of two signal pathways was not altered in unloaded soleus muscle. The AS160 and GLUT4 expression on the common downstream pathway also was not changed in unloaded soleus muscle. But the GLUT4 translocation to sarcolemma was inhibited during insulin stimulation in unloaded soleus muscle. The above results suggest that hindlimb unloading in tail-suspended rat induces atrophy in antigravity soleus muscle. The impaired GLUT4 translocation to sarcolemma under insulin stimulation may mediate insulin resistance in unloaded soleus muscle and further affect the insulin sensitivity of whole body in tail-suspended rats.

Impaired Translocation of GLUT4 Results in Insulin Resistance of Atrophic Soleus Muscle

Directory of Open Access Journals (Sweden)

Peng-Tao Xu

2015-01-01

Full Text Available Whether or not the atrophic skeletal muscle induces insulin resistance and its mechanisms are not resolved now. The antigravity soleus muscle showed a progressive atrophy in 1-week, 2-week, and 4-week tail-suspended rats. Hyperinsulinemic-euglycemic clamp showed that the steady-state glucose infusion rate was lower in 4-week tail-suspended rats than that in the control rats. The glucose uptake rates under insulin- or contraction-stimulation were significantly decreased in 4-week unloaded soleus muscle. The key protein expressions of IRS-1, PI3K, and Akt on the insulin-dependent pathway and of AMPK, ERK, and p38 on the insulin-independent pathway were unchanged in unloaded soleus muscle. The unchanged phosphorylation of Akt and p38 suggested that the activity of two signal pathways was not altered in unloaded soleus muscle. The AS160 and GLUT4 expression on the common downstream pathway also was not changed in unloaded soleus muscle. But the GLUT4 translocation to sarcolemma was inhibited during insulin stimulation in unloaded soleus muscle. The above results suggest that hindlimb unloading in tail-suspended rat induces atrophy in antigravity soleus muscle. The impaired GLUT4 translocation to sarcolemma under insulin stimulation may mediate insulin resistance in unloaded soleus muscle and further affect the insulin sensitivity of whole body in tail-suspended rats.

Shikonin regulates C-MYC and GLUT1 expression through the MST1-YAP1-TEAD1 axis

Energy Technology Data Exchange (ETDEWEB)

Vališ, Karel, E-mail: karel.valis@biomed.cas.cz [Laboratory of Structural Biology and Cell Signaling, Institute of Microbiology, v.v.i., The Czech Academy of Sciences, Prague (Czech Republic); Faculty of Science, Charles University, Prague (Czech Republic); Talacko, Pavel; Grobárová, Valéria [Laboratory of Structural Biology and Cell Signaling, Institute of Microbiology, v.v.i., The Czech Academy of Sciences, Prague (Czech Republic); Faculty of Science, Charles University, Prague (Czech Republic); Černý, Jan [Faculty of Science, Charles University, Prague (Czech Republic); Novák, Petr, E-mail: pnovak@biomed.cas.cz [Laboratory of Structural Biology and Cell Signaling, Institute of Microbiology, v.v.i., The Czech Academy of Sciences, Prague (Czech Republic); Faculty of Science, Charles University, Prague (Czech Republic)

2016-12-10

The general mechanism underlying the tumor suppressor activity of the Hippo signaling pathway remains unclear. In this study, we explore the molecular mechanisms connecting the Hippo signaling pathway with glucose metabolism. We have found that two key regulators of glycolysis, C-MYC and GLUT1, are targets of the Hippo signaling pathway in human leukemia cells. Our results revealed that activation of MST1 by the natural compound shikonin inhibited the expression of GLUT1 and C-MYC. Furthermore, RNAi experiments confirmed the regulation of GLUT1 and C-MYC expression via the MST1-YAP1-TEAD1 axis. Surprisingly, YAP1 was found to positively regulate C-MYC mRNA levels in complex with TEAD1, while it negatively regulates C-MYC levels in cooperation with MST1. Hence, YAP1 serves as a rheostat for C-MYC, which is regulated by MST1. In addition, depletion of MST1 stimulates lactate production, whereas the specific depletion of TEAD1 has an opposite effect. The inhibition of lactate production and cellular proliferation induced by shikonin also depends on the Hippo pathway activity. Finally, a bioinformatic analysis revealed conserved TEAD-binding motifs in the C-MYC and GLUT1 promoters providing another molecular data supporting our observations. In summary, regulation of glucose metabolism could serve as a new tumor suppressor mechanism orchestrated by the Hippo signaling pathway. - Highlights: • Shikonin inhibits C-MYC and GLUT1 expression in MST1 and YAP1 dependent manner. • YAP1-TEAD1 interaction activates C-MYC and GLUT1 expression. • MST1 in cooperation with YAP1 inhibits C-MYC and GLUT1 expression. • MST1-YAP1-TEAD1 axis regulates lactate production by leukemic cells. • MST1 and YAP1 proteins block proliferation of leukemic cells.

 The role of glucose transporter 1 (GLUT1 in the diagnosis and therapy of tumors

Directory of Open Access Journals (Sweden)

Paweł Jóźwiak

2012-03-01

Full Text Available  Malignant cells are known to enhance glucose metabolism, to increase glucose uptake and to inhibit the process of oxidative phosphorylation. Accelerated glycolysis is one of the biochemical characteristics of cancer cells that allow them to compensate the inefficient extraction of energy from glucose in order to continue their uncontrolled growth and proliferation. Upregulation of glucose transport across the plasma membrane is mediated by a family of facilitated glucose transporter proteins named GLUT. Overexpression of GLUTs, especially the hypoxia-responsive GLUT1, has been frequently observed in various human carcinomas. Many studies have reported a correlation between GLUT1 expression level and the grade of tumor aggressiveness, which suggests that GLUT1 expression may be of prognostic significance. Therefore, GLUT1 is a key rate-limiting factor in the transport and glucose metabolism in cancer cells. This paper presents the current state of knowledge on GLUT1 regulation as well as its utility in the diagnosis and therapy of cancers.

Molecular Dynamics Simulations of the Human Glucose Transporter GLUT1.

Directory of Open Access Journals (Sweden)

Min-Sun Park

Full Text Available Glucose transporters (GLUTs provide a pathway for glucose transport across membranes. Human GLUTs are implicated in devastating diseases such as heart disease, hyper- and hypo-glycemia, type 2 diabetes and cancer. The human GLUT1 has been recently crystalized in the inward-facing open conformation. However, there is no other structural information for other conformations. The X-ray structures of E. coli Xylose permease (XylE, a glucose transporter homolog, are available in multiple conformations with and without the substrates D-xylose and D-glucose. XylE has high sequence homology to human GLUT1 and key residues in the sugar-binding pocket are conserved. Here we construct a homology model for human GLUT1 based on the available XylE crystal structure in the partially occluded outward-facing conformation. A long unbiased all atom molecular dynamics simulation starting from the model can capture a new fully opened outward-facing conformation. Our investigation of molecular interactions at the interface between the transmembrane (TM domains and the intracellular helices (ICH domain in the outward- and inward-facing conformation supports that the ICH domain likely stabilizes the outward-facing conformation in GLUT1. Furthermore, inducing a conformational transition, our simulations manifest a global asymmetric rocker switch motion and detailed molecular interactions between the substrate and residues through the water-filled selective pore along a pathway from the extracellular to the intracellular side. The results presented here are consistent with previously published biochemical, mutagenesis and functional studies. Together, this study shed light on the structure and functional relationships of GLUT1 in multiple conformational states.

The t-SNAREs syntaxin4 and SNAP23 but not v-SNARE VAMP2 are indispensable to tether GLUT4 vesicles at the plasma membrane in adipocyte

International Nuclear Information System (INIS)

Kawaguchi, Takayuki; Tamori, Yoshikazu; Kanda, Hajime; Yoshikawa, Mari; Tateya, Sanshiro; Nishino, Naonobu; Kasuga, Masato

2010-01-01

SNARE proteins (VAMP2, syntaxin4, and SNAP23) have been thought to play a key role in GLUT4 trafficking by mediating the tethering, docking and subsequent fusion of GLUT4-containing vesicles with the plasma membrane. The precise functions of these proteins have remained elusive, however. We have now shown that depletion of the vesicle SNARE (v-SNARE) VAMP2 by RNA interference in 3T3-L1 adipocytes inhibited the fusion of GLUT4 vesicles with the plasma membrane but did not affect tethering of the vesicles to the membrane. In contrast, depletion of the target SNAREs (t-SNAREs) syntaxin4 or SNAP23 resulted in impairment of GLUT4 vesicle tethering to the plasma membrane. Our results indicate that the t-SNAREs syntaxin4 and SNAP23 are indispensable for the tethering of GLUT4 vesicles to the plasma membrane, whereas the v-SNARE VAMP2 is not required for this step but is essential for the subsequent fusion event.

GLUT1 deficiency syndrome into adulthood: a follow-up study

NARCIS (Netherlands)

Leen, W.G.; Taher, M.; Verbeek, M.M.; Kamsteeg, E.J.; Warrenburg, B.P.C. van de; Willemsen, M.A.

2014-01-01

GLUT1 deficiency syndrome (GLUT1DS) is a treatable neurometabolic disorder in which glucose transport into the brain is disturbed. Besides the classic phenotype of intellectual disability, epilepsy, and movement disorders, other phenotypes are increasingly recognized. These include, for example,

A potential link between insulin signaling and GLUT4 translocation: Association of Rab10-GTP with the exocyst subunit Exoc6/6b

Energy Technology Data Exchange (ETDEWEB)

Sano, Hiroyuki; Peck, Grantley R. [Department of Biochemistry, Geisel School of Medicine at Dartmouth, Hanover, NH 03755 (United States); Blachon, Stephanie [Hybrigenics Services SAS, 3-5 Impasse Reille, 75014 Paris (France); Lienhard, Gustav E., E-mail: gustav.e.lienhard@dartmouth.edu [Department of Biochemistry, Geisel School of Medicine at Dartmouth, Hanover, NH 03755 (United States)

2015-09-25

Insulin increases glucose transport in fat and muscle cells by stimulating the exocytosis of specialized vesicles containing the glucose transporter GLUT4. This process, which is referred to as GLUT4 translocation, increases the amount of GLUT4 at the cell surface. Previous studies have provided evidence that insulin signaling increases the amount of Rab10-GTP in the GLUT4 vesicles and that GLUT4 translocation requires the exocyst, a complex that functions in the tethering of vesicles to the plasma membrane, leading to exocytosis. In the present study we show that Rab10 in its GTP form binds to Exoc6 and Exoc6b, which are the two highly homologous isotypes of an exocyst subunit, that both isotypes are found in 3T3-L1 adipocytes, and that knockdown of Exoc6, Exoc6b, or both inhibits GLUT4 translocation in 3T3-L1 adipocytes. These results suggest that the association of Rab10-GTP with Exoc6/6b is a molecular link between insulin signaling and the exocytic machinery in GLUT4 translocation. - Highlights: • Insulin stimulates the fusion of vesicles containing GLUT4 with the plasma membrane. • This requires vesicular Rab10-GTP and the exocyst plasma membrane tethering complex. • We find that Rab10-GTP associates with the Exoc6 subunit of the exocyst. • We find that knockdown of Exoc6 inhibits fusion of GLUT4 vesicles with the membrane. • The interaction of Rab10-GTP with Exoc6 potentially links signaling to exocytosis.

Prognostic significance of glucose transporter-1 (GLUT1) gene expression in rectal cancer after preoperative chemoradiotherapy

International Nuclear Information System (INIS)

Saigusa, Susumu; Toiyama, Yuji; Tanaka, Koji; Okugawa, Yoshinaga; Fujikawa, Hiroyuki; Matsushita, Kohei; Uchida, Keiichi; Inoue, Yasuhiro; Kusunoki, Masato

2012-01-01

Most cancer cells exhibit increased glycolysis. The elevated glucose transporter 1 (GLUT1) expression has been reported to be associated with resistance to therapeutic agents and a poor prognosis. We wondered whether GLUT1 expression was associated with the clinical outcome in rectal cancer after preoperative chemoradiotherapy (CRT), and whether glycolysis inhibition could represent a novel anticancer treatment. We obtained total RNA from residual cancer cells using microdissection from a total of 52 rectal cancer specimens from patients who underwent preoperative CRT. We performed transcriptional analyzes, and studied the association of the GLUT1 gene expression levels with the clinical outcomes. In addition, we examined each proliferative response of three selected colorectal cancer cell lines to a glycolysis inhibitor, 3-bromopyruvic acid (3-BrPA), with regard to their expression of the GLUT1 gene. An elevated GLUT1 gene expression was associated with a high postoperative stage, the presence of lymph node metastasis, and distant recurrence. Moreover, elevated GLUT1 gene expression independently predicted both the recurrence-free and overall survival. In the in vitro studies, we observed that 3-BrPA significantly suppressed the proliferation of colon cancer cells with high GLUT1 gene expression, compared with those with low expression. An elevated GLUT1 expression may be a useful predictor of distant recurrence and poor prognosis in rectal cancer patients after preoperative CRT. (author)

Effect of vanadate on glucose transporter (GLUT4) intrinsic activity in skeletal muscle plasma membrane giant vesicles

DEFF Research Database (Denmark)

Kristiansen, S; Youn, J; Richter, Erik

1996-01-01

of vanadate (NaVO3) on glucose transporter (GLUT4) intrinsic activity (V(max) = intrinsic activity x [GLUT4 protein]) was studied in muscle plasma membrane giant vesicles. Giant vesicles (average diameter 7.6 microns) were produced by collagenase treatment of rat skeletal muscle. The vesicles were incubated......) 55% and 60%, respectively, compared with control. The plasma membrane GLUT4 protein content was not changed in response to vanadate. It is concluded that vanadate decreased glucose transport per GLUT4 (intrinsic activity). This finding suggests that regulation of glucose transport in skeletal muscle...

GLUT-1-independent infection of the glioblastoma/astroglioma U87 cells by the human T cell leukemia virus type 1

International Nuclear Information System (INIS)

Jin Qingwen; Agrawal, Lokesh; VanHorn-Ali, Zainab; Alkhatib, Ghalib

2006-01-01

The human glucose transporter protein 1 (GLUT-1) functions as a receptor for human T cell leukemia virus (HTLV). GLUT-1 is a twelve-transmembrane cell surface receptor with six extracellular (ECL) and seven intracellular domains. To analyze HTLV-1 cytotropism, we utilized polyclonal antibodies to a synthetic peptide corresponding to the large extracellular domain of GLUT-1. The antibodies caused significant blocking of envelope (Env)-mediated fusion and pseudotyped virus infection of HeLa cells but had no significant effect on infection of U87 cells. This differential effect correlated with the detection of high-level surface expression of GLUT-1 on HeLa cells and very weak staining of U87 cells. To investigate this in terms of viral cytotropism, we cloned GLUT-1 cDNA from U87 cells and isolated two different versions of cDNA clones: the wild-type sequence (encoding 492 residues) and a mutant cDNA with a 5-base pair deletion (GLUT-1Δ5) between nucleotides 1329 and 1333. The deletion, also detected in genomic DNA, resulted in a frame-shift and premature termination producing a truncated protein of 463 residues. Transfection of the wild-type GLUT-1 but not GLUT-1Δ5 cDNA into CHO cells resulted in efficient surface expression of the human GLUT-1. Co-expression of GLUT-1 with GLUT-1Δ5 produces a trans-inhibition by GLUT-1Δ5 of GLUT-1-mediated HTLV-1 envelope (Env)-mediated fusion. Co-immunoprecipitation experiments demonstrated physical interaction of the wild-type and mutant proteins. Northern blot and RT-PCR analyses demonstrated lower GLUT-1 RNA expression in U87 cells. We propose two mechanisms to account for the impaired cell surface expression of GLUT-1 on U87 cells: low GLUT-1 RNA expression and the formation of GLUT-1/GLUT-1Δ5 heterodimers that are retained intracellularly. Significant RNAi-mediated reduction of endogenous GLUT-1 expression impaired HTLV-1 Env-mediated fusion with HeLa cells but not with U87 cells. We propose a GLUT-1-independent mechanism

GLUT1 deficiency with delayed myelination responding to ketogenic diet.

NARCIS (Netherlands)

Klepper, J.; Engelbrecht, V.; Scheffer, H.; Knaap, M.S. van der; Fiedler, A.

2007-01-01

Monitoring effects of a ketogenic diet in GLUT1 deficiency syndrome without seizures is difficult. Neuroimaging is considered uninformative. We report the case of a boy with neurodevelopmental delay, severe ataxia, an E54X-mutation in the SLC2A1 gene (previously GLUT1), and neuroimaging

GLUT1 deficiency with delayed myelination responding to ketogenic diet

NARCIS (Netherlands)

Klepper, Jörg; Engelbrecht, Volkher; Scheffer, Hans; van der Knaap, Marjo S.; Fiedler, Andreas

2007-01-01

Monitoring effects of a ketogenic diet in GLUT1 deficiency syndrome without seizures is difficult. Neuroimaging is considered uninformative. We report the case of a boy with neurodevelopmental delay, severe ataxia, an E54X-mutation in the SLC2A1 gene (previously GLUT1), and neuroimaging

Multiple signalling pathways redundantly control glucose transporter GLUT4 gene transcription in skeletal muscle

DEFF Research Database (Denmark)

Murgia, Marta; Elbenhardt Jensen, Thomas; Cusinato, Marzia

2009-01-01

on pharmacological evidence. Here, we have used a more specific genetic approach to establish the relative role of the three pathways in fast and slow muscles. Plasmids coding for protein inhibitors of CaMKII or calcineurin were co-transfected in vivo with a GLUT4 enhancer-reporter construct either in normal mice...... or in mice expressing a dominant negative AMPK mutant. GLUT4 reporter activity was not inhibited in the slow soleus muscle by blocking either CaMKII or calcineurin alone, but was inhibited by blocking both pathways. GLUT4 reporter activity was likewise unchanged in the soleus of dnAMPK mice......, but was significantly reduce by incapacitation of either CaMKII or calcineurin in these mice. On the other hand, in the fast tibialis anterior muscle, calcineurin appears to exert a prominent role in the control of GLUT4 reporter activity, independent of CaMKII and AMPK. The results point to a muscle type...

Long-Term Chronic Intermittent Hypobaric Hypoxia Induces Glucose Transporter (GLUT4 Translocation Through AMP-Activated Protein Kinase (AMPK in the Soleus Muscle in Lean Rats

Directory of Open Access Journals (Sweden)

Patricia Siques

2018-06-01

Full Text Available Background: In chronic hypoxia (CH and short-term chronic intermittent hypoxia (CIH exposure, glycemia and insulin levels decrease and insulin sensitivity increases, which can be explained by changes in glucose transport at skeletal muscles involving GLUT1, GLUT4, Akt, and AMPK, as well as GLUT4 translocation to cell membranes. However, during long-term CIH, there is no information regarding whether these changes occur similarly or differently than in other types of hypoxia exposure. This study evaluated the levels of AMPK and Akt and the location of GLUT4 in the soleus muscles of lean rats exposed to long-term CIH, CH, and normoxia (NX and compared the findings.Methods: Thirty male adult rats were randomly assigned to three groups: a NX (760 Torr group (n = 10, a CIH group (2 days hypoxia/2 days NX; n = 10 and a CH group (n = 10. Rats were exposed to hypoxia for 30 days in a hypobaric chamber set at 428 Torr (4,600 m. Feeding (10 g daily and fasting times were accurately controlled. Measurements included food intake (every 4 days, weight, hematocrit, hemoglobin, glycemia, serum insulin (by ELISA, and insulin sensitivity at days 0 and 30. GLUT1, GLUT4, AMPK levels and Akt activation in rat soleus muscles were determined by western blot. GLUT4 translocation was measured with confocal microscopy at day 30.Results: (1 Weight loss and increases in hematocrit and hemoglobin were found in both hypoxic groups (p < 0.05. (2 A moderate decrease in glycemia and plasma insulin was found. (3 Insulin sensitivity was greater in the CIH group (p < 0.05. (4 There were no changes in GLUT1, GLUT4 levels or in Akt activation. (5 The level of activated AMPK was increased only in the CIH group (p < 0.05. (6 Increased GLUT4 translocation to the plasma membrane of soleus muscle cells was observed in the CIH group (p < 0.05.Conclusion: In lean rats experiencing long-term CIH, glycemia and insulin levels decrease and insulin sensitivity increases. Interestingly, there

Wushenziye Formula Improves Skeletal Muscle Insulin Resistance in Type 2 Diabetes Mellitus via PTP1B-IRS1-Akt-GLUT4 Signaling Pathway.

Science.gov (United States)

Tian, Chunyu; Chang, Hong; La, Xiaojin; Li, Ji-An

2017-01-01

Background. Wushenziye formula (WSZYF) is an effective traditional Chinese medicine in the treatment of type 2 diabetes mellitus (T2DM). Aim. This study aimed to identify the effects and underlying mechanisms of WSZYF on improving skeletal muscle insulin resistance in T2DM. Methods. An animal model of T2DM was induced by Goto-Kakizaki diabetes prone rats fed with high fat and sugar for 4 weeks. Insulin resistance model was induced in skeletal muscle cell. Results. In vivo , WSZYF improved general conditions and decreased significantly fasting blood glucose, glycosylated serum protein, glycosylated hemoglobin, insulin concentration, and insulin resistance index of T2DM rats. In vitro , WSZYF enhanced glucose consumption in insulin resistance model of skeletal muscle cell. Furthermore, WSZYF affected the expressions of molecules in regulating T2DM, including increasing the expressions of p-IRS1, p-Akt, and GLUT4, reducing PTP1B expression. Conclusion . These findings displayed the potential of WSZYF as a new drug candidate in the treatment of T2DM and the antidiabetic mechanism of WSZYF is probably mediated through modulating the PTP1B-IRS1-Akt-GLUT4 signaling pathway.

Wushenziye Formula Improves Skeletal Muscle Insulin Resistance in Type 2 Diabetes Mellitus via PTP1B-IRS1-Akt-GLUT4 Signaling Pathway

Directory of Open Access Journals (Sweden)

Chunyu Tian

2017-01-01

Full Text Available Background. Wushenziye formula (WSZYF is an effective traditional Chinese medicine in the treatment of type 2 diabetes mellitus (T2DM. Aim. This study aimed to identify the effects and underlying mechanisms of WSZYF on improving skeletal muscle insulin resistance in T2DM. Methods. An animal model of T2DM was induced by Goto-Kakizaki diabetes prone rats fed with high fat and sugar for 4 weeks. Insulin resistance model was induced in skeletal muscle cell. Results. In vivo, WSZYF improved general conditions and decreased significantly fasting blood glucose, glycosylated serum protein, glycosylated hemoglobin, insulin concentration, and insulin resistance index of T2DM rats. In vitro, WSZYF enhanced glucose consumption in insulin resistance model of skeletal muscle cell. Furthermore, WSZYF affected the expressions of molecules in regulating T2DM, including increasing the expressions of p-IRS1, p-Akt, and GLUT4, reducing PTP1B expression. Conclusion. These findings displayed the potential of WSZYF as a new drug candidate in the treatment of T2DM and the antidiabetic mechanism of WSZYF is probably mediated through modulating the PTP1B-IRS1-Akt-GLUT4 signaling pathway.

Glucose metabolism transporters and epilepsy: only GLUT1 has an established role.

Science.gov (United States)

Hildebrand, Michael S; Damiano, John A; Mullen, Saul A; Bellows, Susannah T; Oliver, Karen L; Dahl, Hans-Henrik M; Scheffer, Ingrid E; Berkovic, Samuel F

2014-02-01

The availability of glucose, and its glycolytic product lactate, for cerebral energy metabolism is regulated by specific brain transporters. Inadequate energy delivery leads to neurologic impairment. Haploinsufficiency of the glucose transporter GLUT1 causes a characteristic early onset encephalopathy, and has recently emerged as an important cause of a variety of childhood or later-onset generalized epilepsies and paroxysmal exercise-induced dyskinesia. We explored whether mutations in the genes encoding the other major glucose (GLUT3) or lactate (MCT1/2/3/4) transporters involved in cerebral energy metabolism also cause generalized epilepsies. A cohort of 119 cases with myoclonic astatic epilepsy or early onset absence epilepsy was screened for nucleotide variants in these five candidate genes. No epilepsy-causing mutations were identified, indicating that of the major energetic fuel transporters in the brain, only GLUT1 is clearly associated with generalized epilepsy. Wiley Periodicals, Inc. © 2014 International League Against Epilepsy.

Co-expression of CD147 and GLUT-1 indicates radiation resistance and poor prognosis in cervical squamous cell carcinoma.

Science.gov (United States)

Huang, Xin-Qiong; Chen, Xiang; Xie, Xiao-Xue; Zhou, Qin; Li, Kai; Li, Shan; Shen, Liang-Fang; Su, Juan

2014-01-01

The aim of this study was to investigate the association of CD147 and GLUT-1, which play important roles in glycolysis in response to radiotherapy and clinical outcomes in patients with locally advanced cervical squamous cell carcinoma (LACSCC). The records of 132 female patients who received primary radiation therapy to treat LACSCC at FIGO stages IB-IVA were retrospectively reviewed. Forty-seven patients with PFS (progression-free survival) of less than 36 months were regarded as radiation-resistant. Eighty-five patients with PFS longer than 36 months were regarded as radiation-sensitive. Using pretreatment paraffin-embedded tissues, we evaluated CD147 and GLUT-1 expression by immunohistochemistry. Overexpression of CD147, GLUT-1, and CD147 and GLUT-1 combined were 44.7%, 52.9% and 36.5%, respectively, in the radiation-sensitive group, and 91.5%, 89.4% and 83.0%, respectively, in the radiation-resistant group. The 5-year progress free survival (PFS) rates in the CD147-low, CD147-high, GLUT-1-low, GLUT-1-high, CD147- and/or GLUT-1-low and CD147- and GLUT-1- dual high expression groups were 66.79%, 87.10%, 52.78%, 85.82%, 55.94%, 82.90% and 50.82%, respectively. CD147 and GLUT-1 co-expression, FIGO stage and tumor diameter were independent poor prognostic factors for patients with LACSCC in multivariate Cox regression analysis. Patients with high expression of CD147 alone, GLUT-1 alone or co-expression of CD147 and GLUT-1 showed greater resistance to radiotherapy and a shorter PFS than those with low expression. In particular, co-expression of CD147 and GLUT-1 can be considered as a negative independent prognostic factor.

Overexpression of protein tyrosine phosphatase-alpha (PTP-alpha) but not PTP-kappa inhibits translocation of GLUT4 in rat adipose cells

DEFF Research Database (Denmark)

Cong, L N; Chen, H; Li, Y

1999-01-01

Protein tyrosine phosphatases (PTPases) are likely to play important roles in insulin action. We recently demonstrated that the nontransmembrane PTPase PTP1B can act as a negative modulator of insulin-stimulated translocation of GLUT4. We now examine the role of PTP-alpha and PTP-kappa (two...... of cell surface GLUT4 in response to insulin and a threefold decrease in insulin sensitivity when compared with control cells expressing only tagged GLUT4. Co-overexpression of PTP-alpha and PTP1B did not have additive effects, suggesting that these PTPases share common substrates. Cells overexpressing...

Sulfonylurea therapy improves glucose disposal without changing skeletal muscle GLUT4 levels in noninsulin-dependent diabetes mellitus subjects

DEFF Research Database (Denmark)

Vestergaard, H; Weinreb, J E; Rosen, A S

1995-01-01

alteration in GLUT4 levels expressed either per microgram membrane protein or per DNA. In summary, the improvement in glycemic control and glucose disposal in NIDDM subjects receiving gliclazide therapy cannot be explained by increased expression of GLUT4 in muscle. Thus, therapeutic effects on insulin......A major pathological feature of noninsulin-dependent diabetes (NIDDM) is defective insulin-stimulated glucose transport in skeletal muscle. When NIDDM subjects are assessed as a group, GLUT4 gene expression in skeletal muscle varies widely and is not different from that in controls. Thus......, longitudinal studies are needed to assess whether changes in GLUT4 expression in muscle of NIDDM subjects could be responsible for changes in glucose disposal. The question is timely because recent studies in transgenic mice show that increasing GLUT4 expression can increase insulin-stimulated glucose uptake...

GLUT-4 content in plasma membrane of muscle from patients with non-insulin-dependent diabetes mellitus

DEFF Research Database (Denmark)

Lund, S; Vestergaard, H; Andersen, P H

1993-01-01

The abundance of GLUT-4 protein in both total crude membrane and plasma membrane fractions of vastus lateralis muscle from 13 obese non-insulin-dependent diabetes mellitus (NIDDM) patients and 14 healthy subjects were examined in the fasting state and after supraphysiological hyperinsulinemia....... In the basal state the immunoreactive mass of GLUT-4 protein both in the crude membrane preparation and in the plasma membrane fraction was similar in NIDDM patients and control subjects. Moreover, in vivo insulin exposure neither for 30 min nor for 4 h had any impact on the content of GLUT-4 protein in plasma...... membranes. With the use of the same methodology, antibody, and achieving the same degree of plasma membrane purification and recovery, we found, however, that intraperitoneal administration of insulin to 7-wk-old rats within 30 min increased the content of GLUT-4 protein more than twofold (P

Chloroquine Increases Glucose Uptake via Enhancing GLUT4 Translocation and Fusion with the Plasma Membrane in L6 Cells

Directory of Open Access Journals (Sweden)

Qi Zhou

2016-05-01

Full Text Available Background/Aims: Chloroquine can induce an increase in the cellular uptake of glucose; however, the underlying mechanism is unclear. Methods: In this study, translocation of GLUT4 and intracellular Ca2+ changes were simultaneously observed by confocal microscope in L6 cells stably over-expressing IRAP-mOrange. The GLUT4 fusion with the plasma membrane (PM was traced using HA-GLUT4-GFP. Glucose uptake was measured using a cell-based glucose uptake assay. GLUT4 protein was detected by Western blotting and mRNA level was detected by RT-PCR. Results: We found that chloroquine induced significant increases in glucose uptake, glucose transporter GLUT4 translocation to the plasma membrane (GTPM, GLUT4 fusion with the PM, and intracellular Ca2+ in L6 muscle cells. Chloroquine-induced increases of GTPM and intracellular Ca2+ were inhibited by Gallein (Gβγ inhibitor and U73122 (PLC inhibitor. However, 2-APB (IP3R blocker only blocked the increase in intracellular Ca2+ but did not inhibit GTPM increase. These results indicate that chloroquine, via the Gβγ-PLC-IP3-IP3R pathway, induces elevation of Ca2+, and this Ca2+ increase does not play a role in chloroqui-ne-evoked GTPM increase. However, GLUT4 fusion with the PM and glucose uptake were significantly inhibited with BAPTA-AM. This suggests that Ca2+ enhances GLUT4 fusion with the PM resulting in glucose uptake increase. Conclusion: Our data indicate that chloroquine via Gβγ-PLC-IP3-IP3R induces Ca2+ elevation, which in turn promotes GLUT4 fusion with the PM. Moreover, chloroquine can enhance GLUT4 trafficking to the PM. These mechanisms eventually result in glucose uptake increase in control and insulin-resistant L6 cells. These findings suggest that chloroquine might be a potential drug for improving insulin tolerance in diabetic patients.

Effects of contraction on localization of GLUT4 and v-SNARE isoforms in rat skeletal muscle

DEFF Research Database (Denmark)

Rose, Adam John; Jeppesen, Jacob; Kiens, Bente

2009-01-01

In skeletal muscle, contractions increase glucose uptake due to a translocation of GLUT4 glucose transporters from intracellular storage sites to the surface membrane. Vesicle associated membrane proteins (VAMPs) are believed to play an important role in docking and fusion of the GLUT4 transporters...... at the surface membrane. However, knowledge about which VAMP isoforms in fact co-localize with GLUT4 vesicles in mature skeletal muscle and whether they translocate during muscle contractions is incomplete. The aim of the present study was to further identify VAMP isoforms which are associated with GLUT4......, there was a redistribution of VAMP2 (+240 +/- 40%), VAMP5 (+79 +/- 9%) and VAMP7 (+79 +/- 29%), but not VAMP3, to fractions enriched in heavy membranes away from low density membranes (-49 +/- 10%, -54 +/- 9%, -14 +/- 11%, respectively) in contracted versus resting muscle. In summary, VAMP2, VAMP3, VAMP5 and VAMP7 co...

Effect of Papaya Seed Extract (Carica papaya Linn. on Glucose Transporter 4 (GLUT 4 Expression of Skeletal Muscle Tissue in Diabetic Mice Induced by High Fructose Diet

Directory of Open Access Journals (Sweden)

Devyani Diah Wulansari

2017-08-01

Full Text Available Ethnobotany surveys show that papaya seeds are widely used as herbs for the management of some diseases such as abdominal discomfort, pain, malaria, diabetes, obesity, and infection. This research was conducted to analyze the effect of papaya seed extract on GLUT4 expression on skeletal muscle tissue of DM type II model induced by high fructose diet. This study used 24 animals, divided into 4 groups of negative control group, treated with papaya seed extract 100 mg / kgBB, 200 mg / kgBW and 300 mg / kgBW, was adapted for 14 days then induced by fructose solution 20% Orally with a dose of 1.86 grams / kgBB for 56 days. The treatment group was given papaya seed extract in accordance with the dose of each group for 14 days. GDP levels was measured using a spectrophotometer. Skeletal muscle tissue is used on the gastrocnemius part. GLUT4 expression was measured through a Immunoreactive Score (IRS method with immunohistochemical staining using GLUT4 polyclonal antibodies. Comparative test results showed that there were significant differences between groups (p <0.05 in final GDP variables and GLUT4 expression. Pearson correlation test results show that the value p = 0.001, meaning there is a significant relationship between GLUT4 expression with final GDP levels. The result of simple linear regression analysis showed that p = 0,000 (<0,05, meaning that dose of papaya seed extract had a significant influence on GLUT4 expression.

Metabolic markers in relation to hypoxia; staining patterns and colocalization of pimonidazole, HIF-1α, CAIX, LDH-5, GLUT-1, MCT1 and MCT4

International Nuclear Information System (INIS)

Rademakers, Saskia E; Lok, Jasper; Kogel, Albert J van der; Bussink, Johan; Kaanders, Johannes HAM

2011-01-01

The cellular response of malignant tumors to hypoxia is diverse. Several important endogenous metabolic markers are upregulated under hypoxic conditions. We examined the staining patterns and co-expression of HIF-1α, CAIX, LDH-5, GLUT-1, MCT1 and MCT4 with the exogenous hypoxic cell marker pimonidazole and the association of marker expression with clinicopathological characteristics. 20 biopsies of advanced head and neck carcinomas were immunohistochemically stained and analyzed. All patients were given the hypoxia marker pimonidazole intravenously 2 h prior to biopsy taking. The tumor area positive for each marker, the colocalization of the different markers and the distribution of the markers in relation to the blood vessels were assessed by semiautomatic quantitative analysis. MCT1 staining was present in hypoxic (pimonidazole stained) as well as non-hypoxic areas in almost equal amounts. MCT1 expression showed a significant overall correlation (r = 0.75, p < 0.001) and strong spatial relationship with CAIX. LDH-5 showed the strongest correlation with pimonidazole (r = 0.66, p = 0.002). MCT4 and GLUT-1 demonstrated a typical diffusion-limited hypoxic pattern and showed a high degree of colocalization. Both MCT4 and CAIX showed a higher expression in the primary tumor in node positive patients (p = 0.09 both). Colocalization and staining patterns of metabolic and hypoxia-related proteins provides valuable additional information over single protein analyses and can improve the understanding of their functions and environmental influences

GLUT4 in cultured skeletal myotubes is segregated from the transferrin receptor and stored in vesicles associated with TGN

DEFF Research Database (Denmark)

Ralston, E; Ploug, Thorkil

1996-01-01

of the constitutive endosomal-lysosomal pathway. To address this question, we have investigated the localization of the endogenous GLUT4 in non-stimulated skeletal myotubes from the cell line C2, by immunofluorescence and immunoelectron microscopy. We have used a panel of antibodies to markers of the Golgi complex...... and in vesicles just beyond, i.e. in the structures that constitute the trans-Golgi network (TGN). In myotubes treated with brefeldin A, the immunofluorescence pattern of GLUT4 is modified, but it differs from both Golgi complex markers and TGN38. Instead, it resembles the pattern of the transferrin receptor...... to the GLUT4-containing tubulo-vesicular elements. In brefeldin A-treated cells, a network of tubules of approximately 70 nm diameter, studded with varicosities, stains for both GLUT4 and transferrin receptor, suggesting that brefeldin A has caused fusion of the transferrin receptor and GLUT4-containing...

The inability of phosphatidylinositol 3-kinase activation to stimulate GLUT4 translocation indicates additional signaling pathways are required for insulin-stimulated glucose uptake.

Science.gov (United States)

Isakoff, S J; Taha, C; Rose, E; Marcusohn, J; Klip, A; Skolnik, E Y

1995-10-24

Recent experimental evidence has focused attention to the role of two molecules, insulin receptor substrate 1 (IRS-1) and phosphatidylinositol 3-kinase (PI3-kinase), in linking the insulin receptor to glucose uptake; IRS-1 knockout mice are insulin resistant, and pharmacological inhibitors of PI3-kinase block insulin-stimulated glucose uptake. To investigate the role of PI3-kinase and IRS-1 in insulin-stimulated glucose uptake we examined whether stimulation of insulin-sensitive cells with platelet-derived growth factor (PDGF) or with interleukin 4 (IL-4) stimulates glucose uptake; the activated PDGF receptor (PDGFR) directly binds and activates PI3-kinase, whereas the IL-4 receptor (IL-4R) activates PI3-kinase via IRS-1 or the IRS-1-related molecule 4PS. We found that stimulation of 3T3-L1 adipocytes with PDGF resulted in tyrosine phosphorylation of the PDGFR and activation of PI3-kinase in these cells. To examine whether IL-4 stimulates glucose uptake, L6 myoblasts were engineered to overexpress GLUT4 as well as both chains of the IL-4R (L6/IL-4R/GLUT4); when these L6/IL-4R/GLUT4 myoblasts were stimulated with IL-4, IRS-1 became tyrosine phosphorylated and associated with PI3-kinase. Although PDGF and IL-4 can activate PI3-kinase in the respective cell lines, they do not possess insulin's ability to stimulate glucose uptake and GLUT4 translocation to the plasma membrane. These findings indicate that activation of PI3-kinase is not sufficient to stimulate GLUT4 translocation to the plasma membrane. We postulate that activation of a second signaling pathway by insulin, distinct from PI3-kinase, is necessary for the stimulation of glucose uptake in insulin-sensitive cells.

Direct evidence of fiber type-dependent GLUT-4 expression in human skeletal muscle

DEFF Research Database (Denmark)

Gaster, M; Poulsen, P; Handberg, A

2000-01-01

GLUT-4 expression in individual fibers of human skeletal muscles in younger and older adults was studied. Furthermore, the dependency of insulin-stimulated glucose uptake on fiber type distribution was investigated. Fiber type distribution was determined in cryosections of muscle biopsies from 8...... of slow fibers in the young (r = -0.45, P > 0.25) or in the elderly (r = 0. 11, P > 0.75) subjects. In conclusion, in human skeletal muscle, GLUT-4 expression is fiber type dependent and decreases with age, particularly in fast muscle fibers....

GLUT4 expression at the plasma membrane is related to fibre volume in human skeletal muscle fibres

DEFF Research Database (Denmark)

Gaster, M; Vach, W; Beck-Nielsen, H

2002-01-01

In this study we examined the relationship between GLUT4 expression at the plasma membrane and muscle fibre size in fibre-typed human muscle fibres by immunocytochemistry and morphometry in order to gain further insight into the regulation of GLUT4 expression. At the site of the plasma membrane...

Dehydroepiandrosterone activates AMP kinase and regulates GLUT4 and PGC-1α expression in C2C12 myotubes

Energy Technology Data Exchange (ETDEWEB)

Yokokawa, Takumi [Laboratory of Sports and Exercise Medicine, Graduate School of Human and Environmental Studies, Kyoto University, Kyoto (Japan); Sato, Koji [Graduate School of Sport & Health Science, Ritsumeikan University, Shiga (Japan); Iwanaka, Nobumasa [The Graduate School of Science and Engineering, Ritsumeikan University, Shiga (Japan); Honda, Hiroki [Graduate School of Sport & Health Science, Ritsumeikan University, Shiga (Japan); Higashida, Kazuhiko [Faculty of Sport Science, Waseda University, Saitama (Japan); Iemitsu, Motoyuki [Graduate School of Sport & Health Science, Ritsumeikan University, Shiga (Japan); Hayashi, Tatsuya [Laboratory of Sports and Exercise Medicine, Graduate School of Human and Environmental Studies, Kyoto University, Kyoto (Japan); Hashimoto, Takeshi, E-mail: thashimo@fc.ritsumei.ac.jp [Graduate School of Sport & Health Science, Ritsumeikan University, Shiga (Japan)

2015-07-17

Exercise and caloric restriction (CR) have been reported to have anti-ageing, anti-obesity, and health-promoting effects. Both interventions increase the level of dehydroepiandrosterone (DHEA) in muscle and blood, suggesting that DHEA might partially mediate these effects. In addition, it is thought that either 5′-adenosine monophosphate-activated protein kinase (AMPK) or peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) mediates the beneficial effects of exercise and CR. However, the effects of DHEA on AMPK activity and PGC-1α expression remain unclear. Therefore, we explored whether DHEA in myotubes acts as an activator of AMPK and increases PGC-1α. DHEA exposure increased glucose uptake but not the phosphorylation levels of Akt and PKCζ/λ in C2C12 myotubes. In contrast, the phosphorylation levels of AMPK were elevated by DHEA exposure. Finally, we found that DHEA induced the expression of the genes PGC-1α and GLUT4. Our current results might reveal a previously unrecognized physiological role of DHEA; the activation of AMPK and the induction of PGC-1α by DHEA might mediate its anti-obesity and health-promoting effects in living organisms. - Highlights: • We assessed whether dehydroepiandrosterone (DHEA) activates AMPK and PGC-1α. • DHEA exposure increased glucose uptake in C2C12 myotubes. • The phosphorylation levels of AMPK were elevated by DHEA exposure. • DHEA induced the expression of the genes PGC-1α and GLUT4. • AMPK might mediate the anti-obesity and health-promoting effects of DHEA.

Dehydroepiandrosterone activates AMP kinase and regulates GLUT4 and PGC-1α expression in C2C12 myotubes

International Nuclear Information System (INIS)

Yokokawa, Takumi; Sato, Koji; Iwanaka, Nobumasa; Honda, Hiroki; Higashida, Kazuhiko; Iemitsu, Motoyuki; Hayashi, Tatsuya; Hashimoto, Takeshi

2015-01-01

Exercise and caloric restriction (CR) have been reported to have anti-ageing, anti-obesity, and health-promoting effects. Both interventions increase the level of dehydroepiandrosterone (DHEA) in muscle and blood, suggesting that DHEA might partially mediate these effects. In addition, it is thought that either 5′-adenosine monophosphate-activated protein kinase (AMPK) or peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) mediates the beneficial effects of exercise and CR. However, the effects of DHEA on AMPK activity and PGC-1α expression remain unclear. Therefore, we explored whether DHEA in myotubes acts as an activator of AMPK and increases PGC-1α. DHEA exposure increased glucose uptake but not the phosphorylation levels of Akt and PKCζ/λ in C2C12 myotubes. In contrast, the phosphorylation levels of AMPK were elevated by DHEA exposure. Finally, we found that DHEA induced the expression of the genes PGC-1α and GLUT4. Our current results might reveal a previously unrecognized physiological role of DHEA; the activation of AMPK and the induction of PGC-1α by DHEA might mediate its anti-obesity and health-promoting effects in living organisms. - Highlights: • We assessed whether dehydroepiandrosterone (DHEA) activates AMPK and PGC-1α. • DHEA exposure increased glucose uptake in C2C12 myotubes. • The phosphorylation levels of AMPK were elevated by DHEA exposure. • DHEA induced the expression of the genes PGC-1α and GLUT4. • AMPK might mediate the anti-obesity and health-promoting effects of DHEA

The effect of Glut1 and c-myc on prognosis in esophageal squamous cell carcinoma of Kazakh and Han patients.

Science.gov (United States)

Zhou, Ya-Xing; Zhou, Ke-Ming; Liu, Qian; Wang, Hui; Wang, Wen; Shi, Yi; Ma, Yu-Qing

2018-04-09

Glucose transporter type 1 (Glut1) plays a crucial role in cancer-specific metabolism. We explored the expression of Glut1 and c-myc, the relationship between them and the effect of Glut1, c-myc on prognosis in esophageal squamous cell carcinoma. Immunohistochemistry was used to examine the expression of Glut1 and c-myc. χ 2 test analyzes the relationship between c-myc, Glut1 and pathological parameters. Spearman correlation analyzes the relationship between c-myc and Glut1. Survival analysis was used to investigate the effect of Glut1 and c-myc on prognosis. Glut1 positivity was associated with tumor size (p C-myc positivity was associated with tumor location (p = 0.015), depth of invasion (p = 0.022) and lymph node metastasis (p = 0.035). There was a positive correlation between c-myc and Glut1 (r = 0.321). Patients with Glut1 c-myc co-expression had poorer prognosis. Inhibiting Glut1 c-myc co-expression may improve the prognosis of esophageal squamous cell carcinoma.

HIF-1α and GLUT-1 Expression in Atypical Endometrial Hyperplasia, Type I and II Endometrial Carcinoma: A Potential Role in Pathogenesis

Science.gov (United States)

Abdou, Asmaa Gaber; Wahed, Moshira Mohammed Abdel; Kassem, Hend Abdou

2016-01-01

Introduction Hypoxia-Inducible Factor 1α (HIF-1α) is one of the major adaptive responses to hypoxia, regulating the activity of glucose transporter -1 (GLUT-1), responsible for glucose uptake. Aim To evaluate the immunohistochemical expression of both HIF-1α and GLUT-1 in type I and II endometrial carcinoma and their correlation with the available clinicopathologic variables in each type. Materials and Methods A retrospective study was conducted on archival blocks diagnosed from pathology department between April 2010 and August 2014 included 9 cases of atypical hyperplasia and 67 cases of endometrial carcinoma. Evaluation of both HIF-1α and GLUT-1 expression using standard immunohistochemical techniques performed on cut sections from selected paraffin embedded blocks. Statistical Analysis Descriptive analysis of the variables and statistical significances were calculated by non-parametric chi-square test using the Statistical Package for the Social Sciences version 12.0 (SPSS). Results HIF-1α was expressed in epithelial (88.9%, 52.2%, 61.2% and 50%) and stromal (33.3%, 74.6%. 71.4% and 83.3%) components of hyperplasia, total cases of EC, type I and II EC, respectively. GLUT-1 was expressed in the epithelial component of 88.9%, 98.5%, 98% and 100% of hyperplasia, total EC cases, type I and II EC, respectively. The necrosis related pattern of epithelial HIF-1α expression was in favour of type II (p=0.018) and grade III (p=0.038). HIF-1α H-score was associated with high apoptosis in both type I and total cases of EC (p=0.04). GLUT-1 H-score was negatively correlated with apoptotic count (p=0.04) and associated with high grade (p=0.003) and advanced stage in total EC (p=0.004). GLUT-1 H-score was correlated with the pattern of HIF-1α staining in all cases of EC (p= 0.04). Conclusion The role of HIF-1α in epithelial cells may differ from that of stromal cells in EC; however they augment the expression of each other supporting the crosstalk between them. The

Impaired muscle glycogen resynthesis after a marathon is not caused by decreased muscle GLUT-4 content

DEFF Research Database (Denmark)

Asp, S; Rohde, T; Richter, Erik

1997-01-01

Our purpose was to investigate whether the slow rate of muscle glycogen resynthesis after a competitive marathon is associated with a decrease in the total muscle content of the muscle glucose transporter (GLUT-4). Seven well-trained marathon runners participated in the study, and muscle biopsies...... were obtained from the lateral head of the gastrocnemius muscle before, immediately after, and 1, 2, and 7 days after the marathon, as were venous blood samples. Muscle GLUT-4 content was unaltered over the experimental period. Muscle glycogen concentration was 758 +/- 53 mmol/kg dry weight before...... the marathon and decreased to 148 +/- 39 mmol/kg dry weight immediately afterward. Despite a carbohydrate-rich diet (containing at least 7 g carbohydrate.kg body mass-1.day-1), the muscle glycogen concentration remained 30% lower than before-race values 2 days after the race, whereas it had returned to before...

Regulation of human trophoblast GLUT1 glucose transporter by insulin-like growth factor I (IGF-I.

Directory of Open Access Journals (Sweden)

Marc U Baumann

Full Text Available Glucose transport to the fetus across the placenta takes place via glucose transporters in the opposing faces of the barrier layer, the microvillous and basal membranes of the syncytiotrophoblast. While basal membrane content of the GLUT1 glucose transporter appears to be the rate-limiting step in transplacental transport, the factors regulating transporter expression and activity are largely unknown. In view of the many studies showing an association between IGF-I and fetal growth, we investigated the effects of IGF-I on placental glucose transport and GLUT1 transporter expression. Treatment of BeWo choriocarcinoma cells with IGF-I increased cellular GLUT1 protein. There was increased basolateral (but not microvillous uptake of glucose and increased transepithelial transport of glucose across the BeWo monolayer. Primary syncytial cells treated with IGF-I also demonstrated an increase in GLUT1 protein. Term placental explants treated with IGF-I showed an increase in syncytial basal membrane GLUT1 but microvillous membrane GLUT1 was not affected. The placental dual perfusion model was used to assess the effects of fetally perfused IGF-I on transplacental glucose transport and syncytial GLUT1 content. In control perfusions there was a decrease in transplacental glucose transport over the course of the perfusion, whereas in tissues perfused with IGF-I through the fetal circulation there was no change. Syncytial basal membranes from IGF-I perfused tissues showed an increase in GLUT1 content. These results demonstrate that IGF-I, whether acting via microvillous or basal membrane receptors, increases the basal membrane content of GLUT1 and up-regulates basal membrane transport of glucose, leading to increased transepithelial glucose transport. These observations provide a partial explanation for the mechanism by which IGF-I controls nutrient supply in the regulation of fetal growth.

Action of Phytochemicals on Insulin Signaling Pathways Accelerating Glucose Transporter (GLUT4 Protein Translocation

Directory of Open Access Journals (Sweden)

Abu Sadat Md Sayem

2018-01-01

Full Text Available Diabetes is associated with obesity, generally accompanied by a chronic state of oxidative stress and redox imbalances which are implicated in the progression of micro- and macro-complications like heart disease, stroke, dementia, cancer, kidney failure and blindness. All these complications rise primarily due to consistent high blood glucose levels. Insulin and glucagon help to maintain the homeostasis of glucose and lipids through signaling cascades. Pancreatic hormones stimulate translocation of the glucose transporter isoform 4 (GLUT4 from an intracellular location to the cell surface and facilitate the rapid insulin-dependent storage of glucose in muscle and fat cells. Malfunction in glucose uptake mechanisms, primarily contribute to insulin resistance in type 2 diabetes. Plant secondary metabolites, commonly known as phytochemicals, are reported to have great benefits in the management of type 2 diabetes. The role of phytochemicals and their action on insulin signaling pathways through stimulation of GLUT4 translocation is crucial to understand the pathogenesis of this disease in the management process. This review will summarize the effects of phytochemicals and their action on insulin signaling pathways accelerating GLUT4 translocation based on the current literature.

Regenerating human muscle fibres express GLUT3 protein

DEFF Research Database (Denmark)

Gaster, M; Beck-Nielsen, H; Schrøder, H D

2002-01-01

The presence of the GLUT3 glucose transporter protein in human muscle cells is a matter of debate. The present study was designed to establish whether GLUT3 is expressed in mature human skeletal muscle fibres and, if so, whether its expression changes under different conditions, such as metabolic...... muscle fibres, nor did metabolic stress, training or de- and re-innervation induce GLUT3 expression, while a few GLUT3 expressing fibres were seen in some cases of polymyositis. In contrast, GLUT4 was expressed in all investigated muscle fibres. GLUT3 immunoreactivity was found in perineural...... and endoneural cells, indicating that GLUT3 is important for glucose transport into nerves through the perineurium. Taken together, these data suggest that GLUT3 expression is restricted to regenerating muscle fibres and nerves in adult human muscle. Although the significance of GLUT3 in adult human muscle...

Gene Expression of Glucose Transporter 1 (GLUT1), Hexokinase 1 and Hexokinase 2 in Gastroenteropancreatic Neuroendocrine Tumors

DEFF Research Database (Denmark)

Binderup, Tina; Knigge, Ulrich; Federspiel, Birgitte Hartnack

2013-01-01

-associated genes and to compare this with FDG-PET imaging as well as with the cellular proliferation index in two cancer entities with different malignant potential. Using real-time PCR, gene expression of GLUT1, HK1 and HK2 were studied in 34 neuroendocrine tumors (NETs) in comparison with 14 colorectal...... adenocarcinomas (CRAs). The Ki67 proliferation index and, when available, FDG-PET imaging was compared with gene expression. Overexpression of GLUT1 gene expression was less frequent in NETs (38%) compared to CRAs (86%), P = 0.004. HK1 was overexpressed in 41% and 71% of NETs and CRAs, respectively (P = 0.......111) and HK2 was overexpressed in 50% and 64% of NETs and CRAs, respectively (P = 0.53). There was a significant correlation between the Ki67 proliferation index and GLUT1 gene expression for the NETs (R = 0.34, P = 0.047), but no correlation with the hexokinases. FDG-PET identified foci in significantly...

Insulin and leptin induce Glut4 plasma membrane translocation and glucose uptake in a human neuronal cell line by a phosphatidylinositol 3-kinase- dependent mechanism.

Science.gov (United States)

Benomar, Yacir; Naour, Nadia; Aubourg, Alain; Bailleux, Virginie; Gertler, Arieh; Djiane, Jean; Guerre-Millo, Michèle; Taouis, Mohammed

2006-05-01

The insulin-sensitive glucose transporter Glut4 is expressed in brain areas that regulate energy homeostasis and body adiposity. In contrast with peripheral tissues, however, the impact of insulin on Glut4 plasma membrane (PM) translocation in neurons is not known. In this study, we examined the role of two anorexic hormones (leptin and insulin) on Glut4 translocation in a human neuronal cell line that express endogenous insulin and leptin receptors. We show that insulin and leptin both induce Glut4 translocation to the PM of neuronal cells and activate glucose uptake. Wortmannin, a specific inhibitor of phosphatidylinositol 3-kinase, totally abolished insulin- and leptin-dependent Glut4 translocation and stimulation of glucose uptake. Thus, Glut4 translocation is a phosphatidylinositol 3-kinase-dependent mechanism in neuronal cells. Next, we investigated the impact of chronic insulin and leptin treatments on Glut4 expression and translocation. Chronic exposure of neuronal cells to insulin or leptin down-regulates Glut4 proteins and mRNA levels and abolishes the acute stimulation of glucose uptake in response to acute insulin or leptin. In addition, chronic treatment with either insulin or leptin impaired Glut4 translocation. A cross-desensitization between insulin and leptin was apparent, where exposure to insulin affects leptin-dependent Glut4 translocation and vice versa. This cross-desensitization could be attributed to the increase in suppressor of cytokine signaling-3 expression, which was demonstrated in response to each hormone. These results provide evidence to suggest that Glut4 translocation to neuronal PM is regulated by both insulin and leptin signaling pathways. These pathways might contribute to an in vivo glucoregulatory reflex involving a neuronal network and to the anorectic effect of insulin and leptin.

Genetic variants in promoters and coding regions of the muscle glycogen synthase and the insulin-responsive GLUT4 genes in NIDDM

DEFF Research Database (Denmark)

Bjørbaek, C; Echwald, Søren Morgenthaler; Hubricht, P

1994-01-01

To examine the hypothesis that variants in the regulatory or coding regions of the glycogen synthase (GS) and insulin-responsive glucose transporter (GLUT4) genes contribute to insulin-resistant glucose processing of muscle from non-insulin-dependent diabetes mellitus (NIDDM) patients, promoter...... volunteers. By applying inverse polymerase chain reaction and direct DNA sequencing, 532 base pairs (bp) of the GS promoter were identified and the transcriptional start site determined by primer extension. SSCP scanning of the promoter region detected five single nucleotide substitutions, positioned at 42......'-untranslated region, and the coding region of the GLUT4 gene showed four polymorphisms, all single nucleotide substitutions, positioned at -581, 1, 30, and 582. None of the three changes in the regulatory region of the gene had any major influence on expression of the GLUT4 gene in muscle. The variant at 582...

Biochemical phenotyping unravels novel metabolic abnormalities and potential biomarkers associated with treatment of GLUT1 deficiency with ketogenic diet.

Science.gov (United States)

Cappuccio, Gerarda; Pinelli, Michele; Alagia, Marianna; Donti, Taraka; Day-Salvatore, Debra-Lynn; Veggiotti, Pierangelo; De Giorgis, Valentina; Lunghi, Simona; Vari, Maria Stella; Striano, Pasquale; Brunetti-Pierri, Nicola; Kennedy, Adam D; Elsea, Sarah H

2017-01-01

Global metabolomic profiling offers novel opportunities for the discovery of biomarkers and for the elucidation of pathogenic mechanisms that might lead to the development of novel therapies. GLUT1 deficiency syndrome (GLUT1-DS) is an inborn error of metabolism due to reduced function of glucose transporter type 1. Clinical presentation of GLUT1-DS is heterogeneous and the disorder mirrors patients with epilepsy, movement disorders, or any paroxysmal events or unexplained neurological manifestation triggered by exercise or fasting. The diagnostic biochemical hallmark of the disease is a reduced cerebrospinal fluid (CSF)/blood glucose ratio and the only available treatment is ketogenic diet. This study aimed at advancing our understanding of the biochemical perturbations in GLUT1-DS pathogenesis through biochemical phenotyping and the treatment of GLUT1-DS with a ketogenic diet. Metabolomic analysis of three CSF samples from GLUT1-DS patients not on ketogenic diet was feasible inasmuch as CSF sampling was used for diagnosis before to start with ketogenic diet. The analysis of plasma and urine samples obtained from GLUT1-DS patients treated with a ketogenic diet showed alterations in lipid and amino acid profiles. While subtle, these were consistent findings across the patients with GLUT1-DS on ketogenic diet, suggesting impacts on mitochondrial physiology. Moreover, low levels of free carnitine were present suggesting its consumption in GLUT1-DS on ketogenic diet. 3-hydroxybutyrate, 3-hydroxybutyrylcarnitine, 3-methyladipate, and N-acetylglycine were identified as potential biomarkers of GLUT1-DS on ketogenic diet. This is the first study to identify CSF, plasma, and urine metabolites associated with GLUT1-DS, as well as biochemical changes impacted by a ketogenic diet. Potential biomarkers and metabolic insights deserve further investigation.

Signal transduction meets vesicle traffic: the software and hardware of GLUT4 translocation.

Science.gov (United States)

Klip, Amira; Sun, Yi; Chiu, Tim Ting; Foley, Kevin P

2014-05-15

Skeletal muscle is the major tissue disposing of dietary glucose, a function regulated by insulin-elicited signals that impart mobilization of GLUT4 glucose transporters to the plasma membrane. This phenomenon, also central to adipocyte biology, has been the subject of intense and productive research for decades. We focus on muscle cell studies scrutinizing insulin signals and vesicle traffic in a spatiotemporal manner. Using the analogy of an integrated circuit to approach the intersection between signal transduction and vesicle mobilization, we identify signaling relays ("software") that engage structural/mechanical elements ("hardware") to enact the rapid mobilization and incorporation of GLUT4 into the cell surface. We emphasize how insulin signal transduction switches from tyrosine through lipid and serine phosphorylation down to activation of small G proteins of the Rab and Rho families, describe key negative regulation step of Rab GTPases through the GTPase-activating protein activity of the Akt substrate of 160 kDa (AS160), and focus on the mechanical effectors engaged by Rabs 8A and 10 (the molecular motor myosin Va), and the Rho GTPase Rac1 (actin filament branching and severing through Arp2/3 and cofilin). Finally, we illustrate how actin filaments interact with myosin 1c and α-Actinin4 to promote vesicle tethering as preamble to fusion with the membrane. Copyright © 2014 the American Physiological Society.

Stereospermum tetragonam as an antidiabetic agent by activating PPARγ and GLUT4

Directory of Open Access Journals (Sweden)

Bino Kingsley

2014-06-01

Full Text Available Present study evaluates the anti-diabetic activity of S. tetragonam LC-MSMS experiments showed the presence of two novel molecules C1 and C2, which were further taken for in silico study against PPARγ. Cell culture studies with A431 cells in the presence of crude aqueous extract showed the elevated level of PPARγ and GLUT4 and also confirmed using in silico studies. Thus, the present study proves the mecode of action of S. tetragonam as an antidiabetic drug.

Expression of Akt and GLUT-4 in adipose tissue of women with gestational diabetes mellitus and pregnant women with excessive weight gain

Directory of Open Access Journals (Sweden)

Li WU

2014-10-01

Full Text Available Objective　To investigate the influence of glucose transporter 4 (GLUT-4 and protein kinase B (Akt on gestational diabetes mellitus (GDM by determining their expressions in adipose tissues from women with GDM, excessive weight gain pregnant women, and normal pregnant women. Methods　Adipose tissues were obtained by biopsy during cesarean section from 15 pregnant women with normal glucose tolerance while their body mass index (BMI increased in about 4kg/m2 (NGT1 group, and 15 pregnant women with normal glucose tolerance with BMI increased by 8kg/m2 (NGT2 group, and 15 cases of GDM (GDM group. Adipose tissue were divided into two sections and incubated in the culture medium with or without insulin (1×10-7 mol/L for 30 minutes. Fasting blood glucose (FBG and fasting insulin (FINS levels were determined with glucose oxidase and radioimmunoassay. Homeostatic model assessment of insulin resistance (HOMA-IR, and homeostatic model assessment of insulin secretions index (HOMA-IS were calculated from the data. Phosphorylation of Akt (P-Akt and GLUT-4 levels of cultured adipose tissue were examined by Western blotting. Results　The FBG levels were similar in 3 groups. FINS, HOMA-IR and HOMA-IS were significantly different among the 3 groups (P0.05 in basal state. Compared with the basal state, however, the phosphorylation of Akt increased significantly in NGT1 group (P0.05 after insulin stimulation. The expression of GLUT-4 was significantly lower in GDM group and NGT2 group than in NGT1 group (P<0.05 in basal state. The expression of GLUT-4 increased much more in NGT1 group than in NGT2 group or GDM group (P<0.05 after insulin stimulation. Conclusion　The excessive weight gain and normal glucose tolerance pregnant women almost share a similar expression with GDM women in the insulin signaling and glucose transporter proteins, Akt and GLUT-4, and their abnormal expression and function might play an important role in insulin resistance and GDM

A novel PTP1B inhibitor extracted from Ganoderma lucidum ameliorates insulin resistance by regulating IRS1-GLUT4 cascades in the insulin signaling pathway.

Science.gov (United States)

Yang, Zhou; Wu, Fan; He, Yanming; Zhang, Qiang; Zhang, Yuan; Zhou, Guangrong; Yang, Hongjie; Zhou, Ping

2018-01-24

Insulin resistance caused by the overexpression of protein tyrosine phosphatase 1 B (PTP1B) as well as the dephosphorylation of its target is one of the main causes of type 2 diabetes (T2D). A newly discovered proteoglycan, Fudan-Yueyang Ganoderma lucidum (FYGL) extracted from Ganoderma lucidum, was first reported to be capable of competitively inhibiting PTP1B activity in vitro in our previous work. In the present study, we sought to reveal the mechanism of PTP1B inhibition by FYGL at the animal and cellular levels. We found that FYGL can decrease blood glucose, reduce body weight and ameliorate insulin resistance in ob/ob mice. Decrease of PTP1B expression and increase of the phosphorylation of PTP1B targets in the insulin signaling pathway of skeletal muscles were observed. In order to clearly reveal the underlying mechanism of the hypoglycemic effect caused by FYGL, we further investigated the effects of FYGL on the PTP1B-involved insulin signaling pathway in rat myoblast L6 cells. We demonstrated that FYGL had excellent cell permeability by using a confocal laser scanning microscope and a flow cytometer. We found that FYGL had a positive effect on insulin-stimulated glucose uptake by using the 2-deoxyglucose (2-DG) method. FYGL could inhibit PTP1B expression at the mRNA level, phosphorylating insulin receptor substrate-1 (IRS1), as well as activating phosphatidylinositol-3 kinase (PI3K) and protein kinase B (Akt). Finally, FYGL increased the phosphorylation of adenosine monophosphate-activated protein kinase (AMPK) and consequently up-regulated the expression of glucose transporter type 4 (GLUT4), promoting GLUT4 transportation to the plasma membrane in PTP1B-transfected L6 cells. Our study provides theoretical evidence for FYGL to be potentially used in T2D management.

Effects of high-intensity swimming training on GLUT-4 and glucose transport activity in rat skeletal muscle.

Science.gov (United States)

Terada, S; Yokozeki, T; Kawanaka, K; Ogawa, K; Higuchi, M; Ezaki, O; Tabata, I

2001-06-01

This study was performed to assess the effects of short-term, extremely high-intensity intermittent exercise training on the GLUT-4 content of rat skeletal muscle. Three- to four-week-old male Sprague-Dawley rats with an initial body weight ranging from 45 to 55 g were used for this study. These rats were randomly assigned to an 8-day period of high-intensity intermittent exercise training (HIT), relatively high-intensity intermittent prolonged exercise training (RHT), or low-intensity prolonged exercise training (LIT). Age-matched sedentary rats were used as a control. In the HIT group, the rats repeated fourteen 20-s swimming bouts with a weight equivalent to 14, 15, and 16% of body weight for the first 2, the next 4, and the last 2 days, respectively. Between exercise bouts, a 10-s pause was allowed. RHT consisted of five 17-min swimming bouts with a 3-min rest between bouts. During the first bout, the rat swam without weight, whereas during the following four bouts, the rat was attached to a weight equivalent to 4 and 5% of its body weight for the first 5 days and the following 3 days, respectively. Rats in the LIT group swam 6 h/day for 8 days in two 3-h bouts separated by 45 min of rest. In the first experiment, the HIT, LIT, and control rats were compared. GLUT-4 content in the epitrochlearis muscle in the HIT and LIT groups after training was significantly higher than that in the control rats by 83 and 91%, respectively. Furthermore, glucose transport activity, stimulated maximally by both insulin (2 mU/ml) (HIT: 48%, LIT: 75%) and contractions (25 10-s tetani) (HIT: 55%, LIT: 69%), was higher in the training groups than in the control rats. However, no significant differences in GLUT-4 content or in maximal glucose transport activity in response to both insulin and contractions were observed between the two training groups. The second experiment demonstrated that GLUT-4 content after HIT did not differ from that after RHT (66% higher in trained rats than

Caffeine inhibition of GLUT1 is dependent on the activation state of the transporter.

Science.gov (United States)

Gunnink, Leesha K; Busscher, Brianna M; Wodarek, Jeremy A; Rosette, Kylee A; Strohbehn, Lauren E; Looyenga, Brendan D; Louters, Larry L

2017-06-01

Caffeine has been shown to be a robust uncompetitive inhibitor of glucose uptake in erythrocytes. It preferentially binds to the nucleotide-binding site on GLUT1 in its tetrameric form and mimics the inhibitory action of ATP. Here we demonstrate that caffeine is also a dose-dependent, uncompetitive inhibitor of 2-deoxyglucose (2DG) uptake in L929 fibroblasts. The inhibitory effect on 2DG uptake in these cells was reversible with a rapid onset and was additive to the competitive inhibitory effects of glucose itself, confirming that caffeine does not interfere with glucose binding. We also report for the first time that caffeine inhibition was additive to inhibition by curcumin, suggesting distinct binding sites for curcumin and caffeine. In contrast, caffeine inhibition was not additive to that of cytochalasin B, consistent with previous data that reported that these two inhibitors have overlapping binding sites. More importantly, we show that the magnitude of maximal caffeine inhibition in L929 cells is much lower than in erythrocytes (35% compared to 90%). Two epithelial cell lines, HCLE and HK2, have both higher concentrations of GLUT1 and increased basal 2DG uptake (3-4 fold) compared to L929 cells, and subsequently display greater maximal inhibition by caffeine (66-70%). Interestingly, activation of 2DG uptake (3-fold) in L929 cells by glucose deprivation shifted the responsiveness of these cells to caffeine inhibition (35%-70%) without a change in total GLUT1 concentration. These data indicate that the inhibition of caffeine is dependent on the activity state of GLUT1, not merely on the concentration. Copyright © 2017 Elsevier B.V. and Société Française de Biochimie et Biologie Moléculaire (SFBBM). All rights reserved.

Insulin-Like Growth Factor (IGF Binding Protein-2, Independently of IGF-1, Induces GLUT-4 Translocation and Glucose Uptake in 3T3-L1 Adipocytes

Directory of Open Access Journals (Sweden)

Biruhalem Assefa

2017-01-01

Full Text Available Insulin-like growth factor binding protein-2 (IGFBP-2 is the predominant IGF binding protein produced during adipogenesis and is known to increase the insulin-stimulated glucose uptake (GU in myotubes. We investigated the IGFBP-2-induced changes in basal and insulin-stimulated GU in adipocytes and the underlying mechanisms. We further determined the role of insulin and IGF-1 receptors in mediating the IGFBP-2 and the impact of IGFBP-2 on the IGF-1-induced GU. Fully differentiated 3T3-L1 adipocytes were treated with IGFBP-2 in the presence and absence of insulin and IGF-1. Insulin, IGF-1, and IGFBP-2 induced a dose-dependent increase in GU. IGFBP-2 increased the insulin-induced GU after long-term incubation. The IGFBP-2-induced impact on GU was neither affected by insulin or IGF-1 receptor blockage nor by insulin receptor knockdown. IGFBP-2 significantly increased the phosphorylation of PI3K, Akt, AMPK, TBC1D1, and PKCζ/λ and induced GLUT-4 translocation. Moreover, inhibition of PI3K and AMPK significantly reduced IGFBP-2-stimulated GU. In conclusion, IGFBP-2 stimulates GU in 3T3-L1 adipocytes through activation of PI3K/Akt, AMPK/TBC1D1, and PI3K/PKCζ/λ/GLUT-4 signaling. The stimulatory effect of IGFBP-2 on GU is independent of its binding to IGF-1 and is possibly not mediated through the insulin or IGF-1 receptor. This study highlights the potential role of IGFBP-2 in glucose metabolism.

GLUT1-mediated selective tumor targeting with fluorine containing platinum(II) glycoconjugates.

Science.gov (United States)

Liu, Ran; Fu, Zheng; Zhao, Meng; Gao, Xiangqian; Li, Hong; Mi, Qian; Liu, Pengxing; Yang, Jinna; Yao, Zhi; Gao, Qingzhi

2017-06-13

Increased glycolysis and overexpression of glucose transporters (GLUTs) are physiological characteristics of human malignancies. Based on the so-called Warburg effect, 18flurodeoxyglucose-positron emission tomography (FDG-PET) has successfully developed as clinical modality for the diagnosis and staging of many cancers. To leverage this glucose transporter mediated metabolic disparity between normal and malignant cells, in the current report, we focus on the fluorine substituted series of glucose, mannose and galactose-conjugated (trans-R,R-cyclohexane-1,2-diamine)-2-flouromalonato-platinum(II) complexes for a comprehensive evaluation on their selective tumor targeting. Besides highly improved water solubility, these sugar-conjugates presented improved cytotoxicity than oxaliplatin in glucose tranporters (GLUTs) overexpressing cancer cell lines and exhibited no cross-resistance to cisplatin. For the highly water soluble glucose-conjugated complex (5a), two novel in vivo assessments were conducted and the results revealed that 5a was more efficacious at a lower equitoxic dose (70% MTD) than oxaliplatin (100% MTD) in HT29 xenograft model, and it was significantly more potent than oxaliplatin in leukemia-bearing DBA/2 mice as well even at equimolar dose levels (18% vs 90% MTD). GLUT inhibitor mediated cell viability analysis, GLUT1 knockdown cell line-based cytotoxicity evaluation, and platinum accumulation study demonstrated that the cellular uptake of the sugar-conjugates was regulated by GLUT1. The higher intrinsic DNA reactivity of the sugar-conjugates was confirmed by kinetic study of platinum(II)-guanosine adduct formation. The mechanistic origin of the antitumor effect of the fluorine complexes was found to be forming the bifunctional Pt-guanine-guanine (Pt-GG) intrastrand cross-links with DNA. The results provide a rationale for Warburg effect targeted anticancer drug design.

Fisetin Suppresses Lipid Accumulation in Mouse Adipocytic 3T3-L1 Cells by Repressing GLUT4-Mediated Glucose Uptake through Inhibition of mTOR-C/EBPα Signaling.

Science.gov (United States)

Watanabe, Marina; Hisatake, Mitsuhiro; Fujimori, Ko

2015-05-27

3,7,3',4'-Tetrahydroxyflavone (fisetin) is a flavonoid found in vegetables and fruits having broad biological activities. Here the effects of fisetin on adipogenesis and its regulatory mechanism in mouse adipocytic 3T3-L1 cells are studied. Fisetin inhibited the accumulation of intracellular lipids and lowered the expression of adipogenic genes such as peroxisome proliferator-activated receptor γ and CCAAT/enhancer-binding protein (C/EBP) α and fatty acid-binding protein 4 (aP2) during adipogenesis. Moreover, the mRNA levels of genes such as acetyl-CoA carboxylase, fatty acid synthase, and stearoyl-CoA desaturase involved in the fatty acid biosynthesis (lipogenesis) were reduced by the treatment with fisetin. The expression level of the glucose transporter 4 (GLUT4) gene was also decreased by fisetin, resulting in down-regulation of glucose uptake. Furthermore, fisetin inhibited the phosphorylation of the mammalian target of rapamycin (mTOR) and that of p70 ribosomal S6 kinase, a target of the mTOR complex, the inhibition of which was followed by a decreased mRNA level of the C/EBPα gene. The results obtained from a chromatin immunoprecipitation assay demonstrated that the ability of C/EBPα to bind to the GLUT4 gene promoter was reduced by the treatment with fisetin, which agreed well with those obtained when 3T3-L1 cells were allowed to differentiate into adipocytes in medium in the presence of rapamycin, an inhibitor for mTOR. These results indicate that fisetin suppressed the accumulation of intracellular lipids by inhibiting GLUT4-mediated glucose uptake through inhibition of the mTOR-C/EBPα signaling in 3T3-L1 cells.

Soybean and sunflower oil-induced insulin resistance correlates with impaired GLUT4 protein expression and translocation specifically in white adipose tissue.

Science.gov (United States)

Poletto, Ana Cláudia; Anhê, Gabriel Forato; Eichler, Paula; Takahashi, Hilton Kenji; Furuya, Daniela Tomie; Okamoto, Maristela Mitiko; Curi, Rui; Machado, Ubiratan Fabres

2010-03-01

Free fatty acids are known for playing a crucial role in the development of insulin resistance. High fat intake is known for impairing insulin sensitivity; however, the effect of vegetable-oil injections have never been investigated. The present study investigated the effects of daily subcutaneous injections (100 microL) of soybean (SB) and sunflower (SF) oils, during 7 days. Both treated groups developed insulin resistance as assessed by insulin tolerance test. The mechanism underlying the SB- and SF-induced insulin resistance was shown to involve GLUT4. In SB- and SF-treated animals, the GLUT4 protein expression was reduced approximately 20% and 10 min after an acute in vivo stimulus with insulin, the plasma membrane GLUT4 content was approximately 60% lower in white adipose tissue (WAT). No effects were observed in skeletal muscle. Additionally, both oil treatments increased mainly the content of palmitic acid ( approximately 150%) in WAT, which can contribute to explain the GLUT4 regulations. Altogether, the present study collects evidence that those oil treatments might generate insulin resistance by targeting GLUT4 expression and translocation specifically in WAT. These alterations are likely to be caused due to the specific local increase in saturated fatty acids that occurred as a consequence of oil daily injections. 2010 John Wiley & Sons, Ltd.

Fruit extracts of Momordica charantia potentiate glucose uptake and up-regulate Glut-4, PPAR gamma and PI3K.

Science.gov (United States)

Kumar, Ramadhar; Balaji, S; Uma, T S; Sehgal, P K

2009-12-10

Momordica charantia fruit is a widely used traditional medicinal herb as, anti-diabetic, anti-HIV, anti-ulcer, anti-inflammatory, anti-leukemic, anti-microbial, and anti-tumor. The present study is undertaken to investigate the possible mode of action of fruit extracts derived from Momordica charantia (MC) and study its pharmacological effects for controlling diabetic mellitus. Effects of aqueous and chloroform extracts of Momordica charantia fruit on glucose uptake and up-regulation of glucose transporter (Glut-4), peroxisome proliferator activator receptor gamma (PPAR gamma) and phosphatidylinositol-3 kinase (PI3K), were investigated to show its efficacy as a hypoglycaemic agent. Dose dependent glucose uptake assay was performed on L6 myotubes using 2-deoxy-D-[1-(3)H] glucose. Up-regulatory effects of the extracts on the mRNA expression level of Glut-4, PPAR gamma and PI3K have been studied. The association of Momordica charantia with the aqueous and chloroform extracts of Momordica charantia fruit at 6 microg/ml has shown significant up-regulatory effect, respectively, by 3.6-, 2.8- and 3.8-fold on the battery of targets Glut-4, PPAR gamma and PI3K involved in glucose transport. The up-regulation of glucose uptake was comparable with insulin and rosiglitazone which was approximately 2-fold over the control. Moreover, the inhibitory effect of the cyclohexamide on Momordica charantia fruit extract mediated glucose uptake suggested the requirement of new protein synthesis for the enhanced glucose uptake. This study demonstrated the significance of Glut-4, PPAR gamma and PI3K up-regulation by Momordica charantia in augmenting the glucose uptake and homeostasis.

Exercise-induced increase in glucose transport, GLUT-4, and VAMP-2 in plasma membrane from human muscle

DEFF Research Database (Denmark)

Kristiansen, S; Hargreaves, Mark; Richter, Erik

1996-01-01

contractions may induce trafficking of GLUT-4-containing vesicles via a mechanism similar to neurotransmitter release. Our results demonstrate for the first time exercise-induced translocation of GLUT-4 and VAMP-2 to the plasma membrane of human muscle and increased sarcolemmal glucose transport.......A major effect of muscle contractions is an increase in sarcolemmal glucose transport. We have used a recently developed technique to produce sarcolemmal giant vesicles from human muscle biopsy samples obtained before and after exercise. Six men exercised for 10 min at 50% maximal O2 uptake (Vo2max...

FDG uptake and glut-1 expression in primary tumors and loco-regional lymph nodes in non-small-cell lung cancer

International Nuclear Information System (INIS)

Lee, Won Woo; Nguyen, Xuan Canh; Chung, Jin Haeng; Park, So Yeon; Kim, Sang Eun

2007-01-01

FDG uptake level by primary tumors in NSCLC may affect the likelihood of malignant involvement in loco-regional lymph nodes (LNs). FDG uptake in tumors has been reported to be mediated by glucose transporter type 1 (Glut-I). Here, we investigated the correlations between primary tumors and loco-regional LNs in NSCLC regarding FDG uptake and Glut-1 expression. 126 NSCLC patients (M: F=103: 23, age=659.7y) who underwent curative resection and loco-regional LN dissection within 4 week period after FDG-PET study were enrolled. Maximum standardized uptake value (maxSUV) by PET and %Glut-1 expression by immunostaining were compared between primary tumors and FDG uptake positive loco-regional LNs. Significant correlations were found between 52 malignant LNs and 37 primary tumors in terms of maxSUV (r=0.6451, p<0.0001) and %Glut-1 expression (r=0.8341, p<0.0001). Linear regression of the relation between maxSUVs of malignant LNs (Y) and maxSUVs of primary tumors (X) yielded the expression Y = 0.5938 + 0.4808 X with an r2 value of 0.4162. On the other hand, no significant correlation was observed between 144 benign LNs and 75 primary tumors in terms of maxSUVs (r= -0.0125, p 0.8831). Moreover, %Glut-1 expressions of pathologically proven benign LNs and primary tumors were found to be correlated (r=0.3863, p=0.0004), but r2 value was low at 0.1492. High correlations were found between primary tumors and loco-regional metastatic LNs in NSCLC regarding FDG uptake and Glut-1 expression. Mediastinal LN staging of NSCLC by FDG-PET may be improved by considering the linear correlation between FDG uptakes of metastatic LNs and primary tumors

Pretreatment HIF-1α and GLUT-1 expressions do not correlate with outcome after preoperative chemoradiotherapy in rectal cancer

DEFF Research Database (Denmark)

Havelund, Birgitte Mayland; Sørensen, Flemming Brandt; Lindebjerg, Jan

2011-01-01

The aim of the present study was to investigate hypoxia-inducible factor 1α (HIF-1α) and glucose transporter-1 (GLUT-1) expressions as predictors of response and survival after chemoradiotherapy in pretreatment biopsy specimens from patients with rectal cancer.......The aim of the present study was to investigate hypoxia-inducible factor 1α (HIF-1α) and glucose transporter-1 (GLUT-1) expressions as predictors of response and survival after chemoradiotherapy in pretreatment biopsy specimens from patients with rectal cancer....

Immunohistological expression of HIF-1α, GLUT-1, Bcl-2 and Ki-67 in consecutive biopsies during chemoradiotherapy in patients with rectal cancer

DEFF Research Database (Denmark)

Havelund, Birgitte Mayland; Sørensen, Flemming Brandt; Pløen, John

2013-01-01

receiving preoperative CRT (>50.4 Gy and Uracil/Tegafur). Immunohistological expressions of HIF-1α, GLUT-1, Bcl-2 and Ki-67 were investigated in biopsies taken before treatment, after 2, 4 and 6 weeks of CRT and in specimens from the operation. Decreasing expressions of HIF-1α, Bcl-2 and Ki-67 were observed...

Deletion of GLUT1 and GLUT3 Reveals Multiple Roles for Glucose Metabolism in Platelet and Megakaryocyte Function

Directory of Open Access Journals (Sweden)

Trevor P. Fidler

2017-07-01

Full Text Available Anucleate platelets circulate in the blood to facilitate thrombosis and diverse immune functions. Platelet activation leading to clot formation correlates with increased glycogenolysis, glucose uptake, glucose oxidation, and lactic acid production. Simultaneous deletion of glucose transporter (GLUT 1 and GLUT3 (double knockout [DKO] specifically in platelets completely abolished glucose uptake. In DKO platelets, mitochondrial oxidative metabolism of non-glycolytic substrates, such as glutamate, increased. Thrombosis and platelet activation were decreased through impairment at multiple activation nodes, including Ca2+ signaling, degranulation, and integrin activation. DKO mice developed thrombocytopenia, secondary to impaired pro-platelet formation from megakaryocytes, and increased platelet clearance resulting from cytosolic calcium overload and calpain activation. Systemic treatment with oligomycin, inhibiting mitochondrial metabolism, induced rapid clearance of platelets, with circulating counts dropping to zero in DKO mice, but not wild-type mice, demonstrating an essential role for energy metabolism in platelet viability. Thus, substrate metabolism is essential for platelet production, activation, and survival.

XbaI GLUT1 Gene Polymorphism and the Risk of Type 2 Diabetes with Nephropathy

Directory of Open Access Journals (Sweden)

Ioannis Stefanidis

2009-01-01

Full Text Available Altered expression of the facilitated glucose transporter GLUT1 affects pathways implicated in the pathogenesis of diabetic nephropathy. There is indication that variation of GLUT1 gene (SLC2A1 contributes to development of microangiopathy in diabetes mellitus type 2 (DM patients. A genetic association study involving Caucasians was carried out to investigate the role of XbαI polymorphism in the GLUT1 gene in diabetic nephropathy (DN. Study population (n = 240 consisted of 148 unrelated patients with DM (92 cases with diabetic nephropathy (DN, and of 92 matched healthy control subjects. Diabetic nephropathy was defined as persistent albuminuria (> 300 mg/24 h and/or renal failure, in the absence of non-diabetes induced renal disease. The analysis showed that the risk of developing DM and DN in XbaI(− carriers, when healthy individuals were considered as controls, was two-fold: odds ratio (OR 2.08 [95% confidence interval (1.14–3.79]. However, there was no evidence of association between XbaI(− and DN when patients with DM and without DN were considered as controls: OR = 1.12 (0.55–2.26. Thus, the GLUT1 XbaI(− allele is associated with DM, and possibly with a more severe form of the disease that can lead to development of DN.

α-Mangostin Improves Glucose Uptake and Inhibits Adipocytes Differentiation in 3T3-L1 Cells via PPARγ, GLUT4, and Leptin Expressions

Directory of Open Access Journals (Sweden)

Muhammad Taher

2015-01-01

Full Text Available Obesity has been often associated with the occurrence of cardiovascular diseases, type 2 diabetes, and cancer. The development of obesity is also accompanied by significant differentiation of preadipocytes into adipocytes. In this study, we investigated the activity of α-mangostin, a major xanthone component isolated from the stem bark of G. malaccensis, on glucose uptake and adipocyte differentiation of 3T3-L1 cells focusing on PPARγ, GLUT4, and leptin expressions. α-Mangostin was found to inhibit cytoplasmic lipid accumulation and adipogenic differentiation. Cells treated with 50 μM of α-mangostin reduced intracellular fat accumulation dose-dependently up to 44.4% relative to MDI-treated cells. Analyses of 2-deoxy-D-[3H] glucose uptake activity showed that α-mangostin significantly improved the glucose uptake (P<0.05 with highest activity found at 25 μM. In addition, α-mangostin increased the amount of free fatty acids (FFA released. The highest glycerol release level was observed at 50 μM of α-mangostin. qRT-PCR analysis showed reduced lipid accumulation via inhibition of PPARγ gene expression. Induction of glucose uptake and free fatty acid release by α-mangostin were accompanied by increasing mRNA expression of GLUT4 and leptin. These evidences propose that α-mangostin might be possible candidate for the effective management of obesity in future.

GLUT4 expression in human muscle fibres is not correlated with intracellular triglyceride (TG) content. Is TG a maker or a marker of insulin resistance?

DEFF Research Database (Denmark)

Gaster, M; Ottosen, P D; Vach, W

2003-01-01

diabetic subjects, and young lean controls. TG density was significantly higher in slow compared to fast fibres in all studied subjects (pslow twitch fibres of obese diabetic subjects compared to obese (p...We have recently reported a progressive decline in the expression of glucose transporter isoform 4 (GLUT4) from control subjects through obese non-diabetics to obese type 2 diabetic subjects, indicating that the reduced GLUT4 in slow twitch fibres could be secondary to obesity. In this study we...... densities in slow and fast fibres did not correlate with the corresponding GLUT4 density in the same fibres in our study groups (p>0.05). Plasma TG and FFA did not correlate with GLUT4 expression in slow or fast fibres (p>0.05). In conclusion, TG content was increased in diabetic slow fibres with a reduced...

Non-invasive assessment of animal exercise stress: real-time PCR of GLUT4, COX2, SOD1 and HSP70 in avalanche military dog saliva.

Science.gov (United States)

Diverio, S; Guelfi, G; Barbato, O; Di Mari, W; Egidi, M G; Santoro, M M

2015-01-01

Exercise has been shown to increase mRNA expression of a growing number of genes. The aim of this study was to assess if mRNA expression of the metabolism- and oxidative stress-related genes GLUT4 (glucose transporter 4), COX2 (cyclooxygenase 2), SOD1 (superoxide dismutase 1) and HSP70 (heat shock protein 70) in saliva changes following acute exercise stress in dogs. For this purpose, 12 avalanche dogs of the Italian Military Force Guardia di Finanza were monitored during simulation of a search for a buried person in an artificial avalanche area. Rectal temperature (RT) and saliva samples were collected the day before the trial (T0), immediately after the descent from a helicopter at the onset of a simulated avalanche search and rescue operation (T1), after the discovery of the buried person (T2) and 2 h later (T3). Expressions of GLUT4, SOD1, COX2 and HSP70 were measured by real-time PCR. The simulated avalanche search and rescue operation was shown to exert a significant effect on RT, as well as on the expression of all metabolism- and oxidative stress-related genes investigated, which peaked at T2. The observed expression patterns indicate an acute exercise stress-induced upregulation, as confirmed by the reductions in expression at T3. Moreover, our findings indicate that saliva is useful for assessing metabolism- and oxidative stress-related genes without the need for restraint, which could affect working dog performance.

Prenatal Exposure to Sodium Arsenite Alters Placental Glucose 1, 3, and 4 Transporters in Balb/c Mice

Directory of Open Access Journals (Sweden)

Daniela Sarahí Gutiérrez-Torres

2015-01-01

Full Text Available Inorganic arsenic (iAs exposure induces a decrease in glucose type 4 transporter (GLUT4 expression on the adipocyte membrane, which may be related to premature births and low birth weight infants in women exposed to iAs at reproductive age. The aim of this study was to analyze the effect of sodium arsenite (NaAsO2 exposure on GLUT1, GLUT3, and GLUT4 protein expression and on placental morphology. Female Balb/c mice (n=15 were exposed to 0, 12, and 20 ppm of NaAsO2 in drinking water from 8th to 18th day of gestation. Morphological changes and GLUT1, GLUT3, and GLUT4 expression were evaluated in placentas by immunohistochemical and image analysis and correlated with iAs and arsenical species concentration, which were quantified by atomic absorption spectroscopy. NaAsO2 exposure induced a significant decrease in fetal and placental weight (P<0.01 and increases in infarctions and vascular congestion. Whereas GLUT1 expression was unchanged in placentas from exposed group, GLUT3 expression was found increased. In contrast, GLUT4 expression was significantly lower (P<0.05 in placentas from females exposed to 12 ppm. The decrease in placental GLUT4 expression might affect the provision of adequate fetal nutrition and explain the low fetal weight observed in the exposed groups.

Ketone Bodies as a Possible Adjuvant to Ketogenic Diet in PDHc Deficiency but Not in GLUT1 Deficiency.

Science.gov (United States)

Habarou, F; Bahi-Buisson, N; Lebigot, E; Pontoizeau, C; Abi-Warde, M T; Brassier, A; Le Quan Sang, K H; Broissand, C; Vuillaumier-Barrot, S; Roubertie, A; Boutron, A; Ottolenghi, C; de Lonlay, P

2018-01-01

Ketogenic diet is the first line therapy for neurological symptoms associated with pyruvate dehydrogenase deficiency (PDHD) and intractable seizures in a number of disorders, including GLUT1 deficiency syndrome (GLUT1-DS). Because high-fat diet raises serious compliance issues, we investigated if oral L,D-3-hydroxybutyrate administration could be as effective as ketogenic diet in PDHD and GLUT1-DS. We designed a partial or total progressive substitution of KD with L,D-3-hydroxybutyrate in three GLUT1-DS and two PDHD patients. In GLUT1-DS patients, we observed clinical deterioration including increased frequency of seizures and myoclonus. In parallel, ketone bodies in CSF decreased after introducing 3-hydroxybutyrate. By contrast, two patients with PDHD showed clinical improvement as dystonic crises and fatigability decreased under basal metabolic conditions. In one of the two PDHD children, 3-hydroxybutyrate has largely replaced the ketogenic diet, with the latter that is mostly resumed only during febrile illness. Positive direct effects on energy metabolism in PDHD patients were suggested by negative correlation between ketonemia and lactatemia (r 2  = 0.59). Moreover, in cultured PDHc-deficient fibroblasts, the increase of CO 2 production after 14 C-labeled 3-hydroxybutyrate supplementation was consistent with improved Krebs cycle activity. However, except in one patient, ketonemia tended to be lower with 3-hydroxybutyrate administration compared to ketogenic diet. 3-hydroxybutyrate may be an adjuvant treatment to ketogenic diet in PDHD but not in GLUT1-DS under basal metabolic conditions. Nevertheless, ketogenic diet is still necessary in PDHD patients during febrile illness.

GLUT4 translocation is not impaired after acute exercise in skeletal muscle of women with obesity and polycystic ovary syndrome.

Science.gov (United States)

Dantas, Wagner Silva; Marcondes, José Antonio Miguel; Shinjo, Samuel Katsuyuki; Perandini, Luiz Augusto; Zambelli, Vanessa Olzon; Neves, Willian Das; Barcellos, Cristiano Roberto Grimaldi; Rocha, Michele Patrocínio; Yance, Viviane Dos Reis Vieira; Pereira, Renato Tavares Dos Santos; Murai, Igor Hisashi; Pinto, Ana Lucia De Sá; Roschel, Hamilton; Gualano, Bruno

2015-11-01

The aim of this study was to examine the effects of acute exercise on insulin signaling in skeletal muscle of women with polycystic ovary syndrome (PCOS) and controls (CTRL). Fifteen women with obesity and PCOS and 12 body mass index-matched CTRL participated in this study. Subjects performed a 40-min single bout of exercise. Muscle biopsies were performed before and 60 min after exercise. Selected proteins were assessed by Western blotting. CTRL, but not PCOS, showed a significant increase in PI3-k p85 and AS160 Thr 642 after a single bout of exercise (P = 0.018 and P = 0.018, respectively). Only PCOS showed an increase in Akt Thr 308 and AMPK phosphorylation after exercise (P = 0.018 and P = 0.018, respectively). Total GLUT4 expression was comparable between groups (P > 0.05). GLUT4 translocation tended to be significantly higher in both groups after exercise (PCOS: P = 0.093; CTRL: P = 0.091), with no significant difference between them (P > 0.05). A single bout of exercise elicited similar GLUT4 translocation in skeletal muscle of PCOS and CTRL, despite a slightly differential pattern of protein phosphorylation. The absence of impairment in GLUT4 translocation suggests that PCOS patients with obesity and insulin resistance may benefit from exercise training. © 2015 The Obesity Society.

Fiber type effects on contraction-stimulated glucose uptake and GLUT4 abundance in single fibers from rat skeletal muscle.

Science.gov (United States)

Castorena, Carlos M; Arias, Edward B; Sharma, Naveen; Bogan, Jonathan S; Cartee, Gregory D

2015-02-01

To fully understand skeletal muscle at the cellular level, it is essential to evaluate single muscle fibers. Accordingly, the major goals of this study were to determine if there are fiber type-related differences in single fibers from rat skeletal muscle for: 1) contraction-stimulated glucose uptake and/or 2) the abundance of GLUT4 and other metabolically relevant proteins. Paired epitrochlearis muscles isolated from Wistar rats were either electrically stimulated to contract (E-Stim) or remained resting (No E-Stim). Single fibers isolated from muscles incubated with 2-deoxy-d-[(3)H]glucose (2-DG) were used to determine fiber type [myosin heavy chain (MHC) isoform protein expression], 2-DG uptake, and abundance of metabolically relevant proteins, including the GLUT4 glucose transporter. E-Stim, relative to No E-Stim, fibers had greater (P contraction-stimulated glucose uptake. Copyright © 2015 the American Physiological Society.

GLUT3 is present in Clone 9 liver cells and translocates to the plasma membrane in response to insulin.

Science.gov (United States)

Defries, Danielle M; Taylor, Carla G; Zahradka, Peter

2016-08-26

Clone 9 cells have been reported to express only the GLUT1 facilitative glucose transporter; however, previous studies have not examined Clone 9 cells for GLUT3 content. The current study sought to profile the presence of glucose transporters in Clone 9 cells, H4IIE hepatoma cells, and L6 myoblasts and myotubes. While the other cell types contained the expected complement of transporters, Clone 9 cells had GLUT3 which was previously not reported. Interestingly, both GLUT3 mRNA and protein were detected in Clone 9 cells, but only mRNA for GLUT1 was detected. Glucose transport in Clone 9 cells was insulin-sensitive in a concentration-dependent manner, concomitant with the presence of GLUT3 in the plasma membrane after insulin treatment. Although basal glucose uptake was unaffected, insulin-stimulated glucose uptake was abolished with siRNA-mediated GLUT3 knockdown. These results contradict previous reports that Clone 9 cells exclusively express GLUT1 and suggest GLUT3 is a key insulin-sensitive glucose transporter required for insulin-stimulated glucose uptake by Clone 9 cells. Copyright © 2016 Elsevier Inc. All rights reserved.

The Effect of a High-Protein Diet and Exercise on Cardiac AQP7 and GLUT4 Gene Expression.

Science.gov (United States)

Palabiyik, Orkide; Karaca, Aziz; Taştekin, Ebru; Yamasan, Bilge Eren; Tokuç, Burcu; Sipahi, Tammam; Vardar, Selma Arzu

2016-10-01

High-protein (HP) diets are commonly consumed by athletes despite their potential health hazard, which is postulated to enforce a negative effect on bone and renal health. However, its effects on heart have not been known yet. Aquaporin-7 (AQP7) is an aquaglyceroporin that facilitates glycerol and water transport. Glycerol is an important cardiac energy production substrate, especially during exercise, in conjunction with fatty acids and glucose. Glucose transporter 4 (GLUT4) is an insulin-sensitive glucose transporter in heart. We aimed to investigate the effect of HPD on AQP7 and GLUT4 levels in the rat heart subjected to exercise. Male Sprague-Dawley rats were divided into control (n = 12), exercise (E) training (n = 10), HPD (n = 12), and HPD-E training (n = 9) groups. The HPD groups were fed a 45 % protein-containing diet 5 weeks. The HPD-E and E groups were performed the treadmill exercise during the 5-week study period. Real-time polymerase chain reaction and immunohistochemistry techniques were used to determine the gene expression and localization of AQP7 and GLUT4 in heart tissue. Results of relative gene expression were calculated by the 'Pfaffl' mathematical method using the REST program. Differences in AQP7 and GLUT4 gene expression were expressed as fold change compared to the control group. Heart weight/tibia ratio and ventricular wall thickness were evaluated as markers of cardiac hypertrophy. Further, serum glucose, glycerol, and insulin levels were also measured. AQP7 gene expression was found to be increased in the E (3.47-fold, p protein expression was also increased in the HPD and HPD-E groups (p protein expression was significantly increased in the E, HPD, and HPD-E groups compared to the control group (p = 0.024, p protein diet groups (C and E). Serum insulin levels were higher for HPD groups compared with the normal-protein diet groups (p < 0.001), whereas no differences were observed between the exercise and sedentary

The FDG uptake and glucose transporter(GLUT-1) expression of the mediastinal nodes in the non-small cell lung cancer

International Nuclear Information System (INIS)

Baik, Hee Jong; Jung, Jin Haeng

2000-12-01

The aim of this study was to understand the mechanism of FDG uptake in the mediastinal nodes, and improve the accuracy of mediastinal staging of non-small cell lung cancer by PET. To evaluate factors determining the FDG uptake in mediastinal nodes, FDG-PET was performed preoperatively, and mediastinal dissection with pulmonary resection was done in 20 LSCLC patients. The GLUT-1 expression was studied by immunohistochemistry of paraffin-section from the mediastinal nodes(n=50, true positive 11, true negative 23, false positive 11, false negative 5) using the antiGLUT-1 antibody. The staining intensity of tumor(grade 0-4), percentage of tumor, level of follicular hyperplasia(grade 1-4), and staining intensity of follicle was also studied. The staining intensity of true positive nodes was higher than that of false negative group(Mann-Whitney test, P=0.07) in the metastased nodes. The level of follicular hyperplasia of false positive nodes was higher than that of true negative nodes in non-metastased nodes(P=0.02). This finding indicates that FN interpretation of mediastinal nodes by FDG-PET might be associated with low uptake of FDG due to low expression of GLUT-1, and that FP might be associated with high level of follicular hyperplasia as a reactive change to inflammatory and/or immune reaction

Similar [DE]XXXL[LI] motifs differentially target GLUT8 and GLUT12 in Chinese Hamster Ovary Cells

OpenAIRE

Flessner, Lauren B.; Moley, Kelle H.

2008-01-01

The transport of glucose across cell membranes is mediated by facilitative glucose transporters. The recently identified Class III glucose transporter GLUT12 is predominantly expressed in insulin-sensitive tissues such as heart, fat, and skeletal muscle. We examined the subcellular localization of GLUT12 in CHO and HEK293 cells stably expressing murine GLUT12. We have previously shown that another Class III glucose transporter, GLUT8, contains a [DE]XXXL[LI] motif that directs it to late endo...

Gene Expression of Glucose Transporter 1 (GLUT1, Hexokinase 1 and Hexokinase 2 in Gastroenteropancreatic Neuroendocrine Tumors: Correlation with F-18-fluorodeoxyglucose Positron Emission Tomography and Cellular Proliferation

Directory of Open Access Journals (Sweden)

Andreas Kjaer

2013-10-01

Full Text Available Neoplastic tissue exhibits high glucose utilization and over-expression of glucose transporters (GLUTs and hexokinases (HKs, which can be imaged by 18F-Fluorodeoxyglucose-positron emission tomography (FDG-PET. The aim of the present study was to investigate the expression of glycolysis-associated genes and to compare this with FDG-PET imaging as well as with the cellular proliferation index in two cancer entities with different malignant potential. Using real-time PCR, gene expression of GLUT1, HK1 and HK2 were studied in 34 neuroendocrine tumors (NETs in comparison with 14 colorectal adenocarcinomas (CRAs. The Ki67 proliferation index and, when available, FDG-PET imaging was compared with gene expression. Overexpression of GLUT1 gene expression was less frequent in NETs (38% compared to CRAs (86%, P = 0.004. HK1 was overexpressed in 41% and 71% of NETs and CRAs, respectively (P = 0.111 and HK2 was overexpressed in 50% and 64% of NETs and CRAs, respectively (P = 0.53. There was a significant correlation between the Ki67 proliferation index and GLUT1 gene expression for the NETs (R = 0.34, P = 0.047, but no correlation with the hexokinases. FDG-PET identified foci in significantly fewer NETs (36% than CRAs (86%, (P = 0.04. The gene expression results, with less frequent GLUT1 and HK1 upregulation in NETs, confirmed the lower metabolic activity of NETs compared to the more aggressive CRAs. In accordance with this, fewer NETs were FDG-PET positive compared to CRA tumors and FDG uptake correlated with GLUT1 gene expression.

Anti-Diabetic Activities of Jiaotaiwan in db/db Mice by Augmentation of AMPK Protein Activity and Upregulation of GLUT4 Expression

Directory of Open Access Journals (Sweden)

Na Hu

2013-01-01

Full Text Available Jiaotaiwan (JTW, which is composed of Coptis chinensis (CC and cinnamon (CIN, is one of the most well-known traditional Chinese medicines. In this study, we investigated the antidiabetic effects and mechanism of JTW in db/db mice. Results showed that JTW significantly decreased the level of fasting blood glucose and improved glucose and insulin tolerance better than CC or CIN alone. JTW also effectively protected the pancreatic islet shape, augmented the activation of AMP-activated protein kinase (AMPK in the liver, and increased the expression of glucose transporter 4 (GLUT4 protein in skeletal muscle and white fat. AMPK and GLUT4 contributed to glucose metabolism regulation and had an essential function in the development of diabetes mellitus (DM. Therefore, the mechanisms of JTW may be related to suppressing gluconeogenesis by activating AMPK in the liver and affecting glucose uptake in surrounding tissues through the upregulation of GLUT4 protein expression. These findings provided a new insight into the antidiabetic clinical applications of JTW and demonstrated the potential of JTW as a new drug candidate for DM treatment.

VEGF and GLUT1 are highly heritable, inversely correlated and affected by dietary fat intake: Consequences for cognitive function in humans

Directory of Open Access Journals (Sweden)

Rita Schüler

2018-05-01

Full Text Available Objective: Reduction of brain glucose transporter GLUT1 results in severe neurological dysfunction. VEGF is required to restore and maintain brain glucose uptake across the blood brain barrier via GLUT1, which was shown to be acutely diminished in response to a high fat diet (HFD in mice. The genetic and HFD-related regulation and association of VEGF and GLUT1 (SLC2A1 in humans was investigated in the NUtriGenomic Analysis in Twins (NUGAT study. Methods: 92 healthy and non-obese twins were standardized to a high-carbohydrate low-fat diet for 6 weeks before switched to a 6-week HFD under isocaloric conditions. Three clinical investigation days were conducted: after 6 weeks of low-fat diet and after 1 and 6 weeks of HFD. Serum VEGF and other cytokine levels were measured using ELISA. Gene expression in subcutaneous adipose tissue was assessed by quantitative Real-Time PCR. Genotyping was performed using microarray. The Auditory Verbal Learning Task was conducted to measure cognitive performance. Results: In this human study, we showed that the environmental regulation of SLC2A1 expression and serum VEGF by HFD was inversely correlated and both factors showed strong heritability (>90%. In response to the HFD containing 45% fat, serum VEGF levels increased (P = 0.002 while SLC2A1 mRNA expression in adipose tissue decreased (P = 0.001. Higher BMI was additionally associated with lower SLC2A1 expression. AA-genotypes of the rs9472159 polymorphism, which explained ∼39% of the variation in circulating VEGF concentrations, showed significantly reduced serum VEGF levels (P = 6.4 × 10−11 but higher SLC2A1 expression (P = 0.009 in adipose tissue compared to CC/CA-genotypes after 6 weeks of HFD. Memory performance in AA-genotypes declined in response to the HFD compared to CC- and CA-genotypes. Conclusions: The results provide evidence to suggest the translatability of the dietary regulation of VEGF and GLUT1 from mouse models to humans. Our

The Role of Hypoxia-Inducible Factor-1α, Glucose Transporter-1, (GLUT-1 and Carbon Anhydrase IX in Endometrial Cancer Patients

Directory of Open Access Journals (Sweden)

Pawel Sadlecki

2014-01-01

Full Text Available Hypoxia-inducible factor-1α (HIF-1α, glucose transporter-1 (GLUT-1, and carbon anhydrase IX (CAIX are important molecules that allow adaptation to hypoxic environments. The aim of our study was to investigate the correlation between HIF-1α, GLUT-1, and CAIX protein level with the clinicopathological features of endometrial cancer patients. Materials and Methods. 92 endometrial cancer patients, aged 37–84, were enrolled to our study. In all patients clinical stage, histologic grade, myometrial invasion, lymph node, and distant metastases were determined. Moreover, the survival time was assessed. Immunohistochemical analyses were performed on archive formalin fixed paraffin embedded tissue sections. Results. High significant differences (P=0.0115 were reported between HIF-1α expression and the histologic subtype of cancer. Higher HIF-1α expression was associated with the higher risk of recurrence (P=0.0434. The results of GLUT-1 and CAIX expression did not reveal any significant differences between the proteins expression in the primary tumor and the clinicopathological features. Conclusion. The important role of HIF-1α in the group of patients with the high risk of recurrence and the negative histologic subtype of the tumor suggest that the expression of this factor might be useful in the panel of accessory pathomorphological tests and could be helpful in establishing more accurate prognosis in endometrial cancer patients.

Adenovirus Protein E4-ORF1 Activation of PI3 Kinase Reveals Differential Regulation of Downstream Effector Pathways in Adipocytes.

Science.gov (United States)

Chaudhary, Natasha; Gonzalez, Eva; Chang, Sung-Hee; Geng, Fuqiang; Rafii, Shahin; Altorki, Nasser K; McGraw, Timothy E

2016-12-20

Insulin activation of phosphatidylinositol 3-kinase (PI3K) regulates metabolism, including the translocation of the Glut4 glucose transporter to the plasma membrane and inactivation of the FoxO1 transcription factor. Adenoviral protein E4-ORF1 stimulates cellular glucose metabolism by mimicking growth-factor activation of PI3K. We have used E4-ORF1 as a tool to dissect PI3K-mediated signaling in adipocytes. E4-ORF1 activation of PI3K in adipocytes recapitulates insulin regulation of FoxO1 but not regulation of Glut4. This uncoupling of PI3K effects occurs despite E4-ORF1 activating PI3K and downstream signaling to levels achieved by insulin. Although E4-ORF1 does not fully recapitulate insulin's effects on Glut4, it enhances insulin-stimulated insertion of Glut4-containing vesicles to the plasma membrane independent of Rab10, a key regulator of Glut4 trafficking. E4-ORF1 also stimulates plasma membrane translocation of ubiquitously expressed Glut1 glucose transporter, an effect that is likely essential for E4-ORF1 to promote an anabolic metabolism in a broad range of cell types. Copyright © 2016 The Author(s). Published by Elsevier Inc. All rights reserved.

Adenovirus Protein E4-ORF1 Activation of PI3 Kinase Reveals Differential Regulation of Downstream Effector Pathways in Adipocytes

Directory of Open Access Journals (Sweden)

Natasha Chaudhary

2016-12-01

Full Text Available Insulin activation of phosphatidylinositol 3-kinase (PI3K regulates metabolism, including the translocation of the Glut4 glucose transporter to the plasma membrane and inactivation of the FoxO1 transcription factor. Adenoviral protein E4-ORF1 stimulates cellular glucose metabolism by mimicking growth-factor activation of PI3K. We have used E4-ORF1 as a tool to dissect PI3K-mediated signaling in adipocytes. E4-ORF1 activation of PI3K in adipocytes recapitulates insulin regulation of FoxO1 but not regulation of Glut4. This uncoupling of PI3K effects occurs despite E4-ORF1 activating PI3K and downstream signaling to levels achieved by insulin. Although E4-ORF1 does not fully recapitulate insulin’s effects on Glut4, it enhances insulin-stimulated insertion of Glut4-containing vesicles to the plasma membrane independent of Rab10, a key regulator of Glut4 trafficking. E4-ORF1 also stimulates plasma membrane translocation of ubiquitously expressed Glut1 glucose transporter, an effect that is likely essential for E4-ORF1 to promote an anabolic metabolism in a broad range of cell types.

Humanin (HN and glucose transporter 8 (GLUT8 in pregnancies complicated by intrauterine growth restriction.

Directory of Open Access Journals (Sweden)

Carla Janzen

Full Text Available Intrauterine growth restriction (IUGR results from a lack of nutrients transferred to the developing fetus, particularly oxygen and glucose. Increased expression of the cytoprotective mitochondrial peptide, humanin (HN, and the glucose transporter 8, GLUT8, has been reported under conditions of hypoxic stress. However, the presence and cellular localization of HN and GLUT8 in IUGR-related placental pathology remain unexplored. Thus, we undertook this study to investigate placental expression of HN and GLUT8 in IUGR-affected versus normal pregnancies.We found 1 increased HN expression in human IUGR-affected pregnancies on the maternal aspect of the placenta (extravillous trophoblastic (EVT cytoplasm compared to control (i.e. appropriate for gestational age pregnancies, and a concomitant increase in GLUT8 expression in the same compartment, 2 HN and GLUT8 showed a protein-protein interaction by co-immunoprecipitation, 3 elevated HN and GLUT8 levels in vitro under simulated hypoxia in human EVT cells, HTR8/SVneo, and 4 increased HN expression but attenuated GLUT8 expression in vitro under serum deprivation in HTR8/SVneo cells.There was elevated HN expression with cytoplasmic localization to EVTs on the maternal aspect of the human placenta affected by IUGR, also associated with increased GLUT8 expression. We found that while hypoxia increased both HN and GLUT8, serum deprivation increased HN expression alone. Also, a protein-protein interaction between HN and GLUT8 suggests that their interaction may fulfill a biologic role that requires interdependency. Future investigations delineating molecular interactions between these proteins are required to fully uncover their role in IUGR-affected pregnancies.

Molecular Tools for Facilitative Carbohydrate Transporters (Gluts).

Science.gov (United States)

Tanasova, Marina; Fedie, Joseph R

2017-09-19

Facilitative carbohydrate transporters-Gluts-have received wide attention over decades due to their essential role in nutrient uptake and links with various metabolic disorders, including diabetes, obesity, and cancer. Endeavors directed towards understanding the mechanisms of Glut-mediated nutrient uptake have resulted in a multidisciplinary research field spanning protein chemistry, chemical biology, organic synthesis, crystallography, and biomolecular modeling. Gluts became attractive targets for cancer research and medicinal chemistry, leading to the development of new approaches to cancer diagnostics and providing avenues for cancer-targeting therapeutics. In this review, the current state of knowledge of the molecular interactions behind Glut-mediated sugar uptake, Glut-targeting probes, therapeutics, and inhibitors are discussed. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Glucose transporter 1 and monocarboxylate transporters 1, 2, and 4 localization within the glial cells of shark blood-brain-barriers.

Directory of Open Access Journals (Sweden)

Carolina Balmaceda-Aguilera

Full Text Available Although previous studies showed that glucose is used to support the metabolic activity of the cartilaginous fish brain, the distribution and expression levels of glucose transporter (GLUT isoforms remained undetermined. Optic/ultrastructural immunohistochemistry approaches were used to determine the expression of GLUT1 in the glial blood-brain barrier (gBBB. GLUT1 was observed solely in glial cells; it was primarily located in end-feet processes of the gBBB. Western blot analysis showed a protein with a molecular mass of 50 kDa, and partial sequencing confirmed GLUT1 identity. Similar approaches were used to demonstrate increased GLUT1 polarization to both apical and basolateral membranes in choroid plexus epithelial cells. To explore monocarboxylate transporter (MCT involvement in shark brain metabolism, the expression of MCTs was analyzed. MCT1, 2 and 4 were expressed in endothelial cells; however, only MCT1 and MCT4 were present in glial cells. In neurons, MCT2 was localized at the cell membrane whereas MCT1 was detected within mitochondria. Previous studies demonstrated that hypoxia modified GLUT and MCT expression in mammalian brain cells, which was mediated by the transcription factor, hypoxia inducible factor-1. Similarly, we observed that hypoxia modified MCT1 cellular distribution and MCT4 expression in shark telencephalic area and brain stem, confirming the role of these transporters in hypoxia adaptation. Finally, using three-dimensional ultrastructural microscopy, the interaction between glial end-feet and leaky blood vessels of shark brain was assessed in the present study. These data suggested that the brains of shark may take up glucose from blood using a different mechanism than that used by mammalian brains, which may induce astrocyte-neuron lactate shuttling and metabolic coupling as observed in mammalian brain. Our data suggested that the structural conditions and expression patterns of GLUT1, MCT1, MCT2 and MCT4 in shark

Tunable GLUT-Hexose Binding and Transport via Modulation of Hexose C-3 Hydrogen-Bonding Capabilities.

Science.gov (United States)

Kumar Kondapi, Venkata Pavan; Soueidan, Olivier-Mohamad; Cheeseman, Christopher I; West, Frederick G

2017-06-12

The importance of the hydrogen bonding interactions in the GLUT-hexose binding process (GLUT=hexose transporter) has been demonstrated by studying the binding of structurally modified d-fructose analogues to GLUTs, and in one case its transport into cells. The presence of a hydrogen bond donor at the C-3 position of 2,5-anhydro-d-mannitol derivatives is essential for effective binding to GLUT5 and transport into tumor cells. Surprisingly, installation of a group that can function only as a hydrogen bond acceptor at C-3 resulted in selective recognition by GLUT1 rather than GLUT5. A fluorescently labelled analogue clearly showed GLUT-mediated transport and low efflux properties of the probe. This study reveals that a single positional modification of a 2,5-anhydro-d-mannitol derivative is sufficient to switch its binding preference from GLUT5 to GLUT1, and uncovers general scaffolds that are suitable for the potential selective delivery of molecular payloads into tumor cells via GLUT transport machinery. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

FGT-1 is a mammalian GLUT2-like facilitative glucose transporter in Caenorhabditis elegans whose malfunction induces fat accumulation in intestinal cells.

Directory of Open Access Journals (Sweden)

Shun Kitaoka

Full Text Available Caenorhabditis elegans (C. elegans is an attractive animal model for biological and biomedical research because it permits relatively easy genetic dissection of cellular pathways, including insulin/IGF-like signaling (IIS, that are conserved in mammalian cells. To explore C. elegans as a model system to study the regulation of the facilitative glucose transporter (GLUT, we have characterized the GLUT gene homologues in C. elegans: fgt-1, R09B5.11, C35A11.4, F53H8.3, F48E3.2, F13B12.2, Y61A9LA.1, K08F9.1 and Y37A1A.3. The exogenous expression of these gene products in Xenopus oocytes showed transport activity to unmetabolized glucose analogue 2-deoxy-D-glucose only in FGT-1. The FGT-1-mediated transport activity was inhibited by the specific GLUT inhibitor phloretin and exhibited a Michaelis constant (Km of 2.8 mM. Mannose, galactose, and fructose were able to inhibit FGT-1-mediated 2-deoxy-D-glucose uptake (P < 0.01, indicating that FGT-1 is also able to transport these hexose sugars. A GFP fusion protein of FGT-1 was observed only on the basolateral membrane of digestive tract epithelia in C. elegans, but not in other tissues. FGT-1::eGFP expression was observed from early embryonic stages. The knockdown or mutation of fgt-1 resulted in increased fat staining in both wild-type and daf-2 (mammalian insulin receptor homologue mutant animals. Other common phenotypes of IIS mutant animals, including dauer formation and brood size reduction, were not affected by fgt-1 knockdown in wild-type or daf-2 mutants. Our results indicated that in C. elegans, FGT-1 is mainly a mammalian GLUT2-like intestinal glucose transporter and is involved in lipid metabolism.

GLUT2-mediated glucose uptake and availability are required for embryonic brain development in zebrafish.

Science.gov (United States)

Marín-Juez, Rubén; Rovira, Mireia; Crespo, Diego; van der Vaart, Michiel; Spaink, Herman P; Planas, Josep V

2015-01-01

Glucose transporter 2 (GLUT2; gene name SLC2A2) has a key role in the regulation of glucose dynamics in organs central to metabolism. Although GLUT2 has been studied in the context of its participation in peripheral and central glucose sensing, its role in the brain is not well understood. To decipher the role of GLUT2 in brain development, we knocked down slc2a2 (glut2), the functional ortholog of human GLUT2, in zebrafish. Abrogation of glut2 led to defective brain organogenesis, reduced glucose uptake and increased programmed cell death in the brain. Coinciding with the observed localization of glut2 expression in the zebrafish hindbrain, glut2 deficiency affected the development of neural progenitor cells expressing the proneural genes atoh1b and ptf1a but not those expressing neurod. Specificity of the morphant phenotype was demonstrated by the restoration of brain organogenesis, whole-embryo glucose uptake, brain apoptosis, and expression of proneural markers in rescue experiments. These results indicate that glut2 has an essential role during brain development by facilitating the uptake and availability of glucose and support the involvement of glut2 in brain glucose sensing.

Inhibitors of GLUT/SLC2A Enhance the Action of BCNU and Temozolomide against High-Grade Gliomas

Directory of Open Access Journals (Sweden)

Alberto Azzalin

2017-04-01

Full Text Available Glucose transport across glioblastoma membranes plays a crucial role in maintaining the enhanced glycolysis typical of high-grade gliomas and glioblastoma. We tested the ability of two inhibitors of the glucose transporters GLUT/SLC2A superfamily, indinavir (IDV and ritonavir (RTV, and of one inhibitor of the Na/glucose antiporter type 2 (SGLT2/SLC5A2 superfamily, phlorizin (PHZ, in decreasing glucose consumption and cell proliferation of human and murine glioblastoma cells. We found in vitro that RTV, active on at least three different GLUT/SLC2A transporters, was more effective than IDV, a specific inhibitor of GLUT4/SLC2A4, both in decreasing glucose consumption and lactate production and in inhibiting growth of U87MG and Hu197 human glioblastoma cell lines and primary cultures of human glioblastoma. PHZ was inactive on the same cells. Similar results were obtained when cells were grown in adherence or as 3D multicellular tumor spheroids. RTV treatment but not IDV treatment induced AMP-activated protein kinase (AMPKα phosphorylation that paralleled the decrease in glycolytic activity and cell growth. IDV, but not RTV, induced an increase in GLUT1/SLC2A1 whose activity could compensate for the inhibition of GLUT4/SLC2A4 by IDV. RTV and IDV pass poorly the blood brain barrier and are unlikely to reach sufficient liquoral concentrations in vivo to inhibit glioblastoma growth as single agents. Isobologram analysis of the association of RTV or IDV and 1,3-bis(2-chloroethyl-1-nitrosourea (BCNU or 4-methyl-5-oxo-2,3,4,6,8-pentazabicyclo[4.3.0]nona-2,7,9-triene-9-carboxamide (TMZ indicated synergy only with RTV on inhibition of glioblastoma cells. Finally, we tested in vivo the combination of RTV and BCNU on established GL261 tumors. This drug combination increased the overall survival and allowed a five-fold reduction in the dose of BCNU.

GLUT4 and glycogen synthase are key players in bed rest-induced insulin resistance

DEFF Research Database (Denmark)

Biensø, Rasmus Sjørup; Jørgensen, Stine Ringholm; Kiilerich, Kristian

2012-01-01

To elucidate the molecular mechanisms behind physical inactivity-induced insulin resistance in skeletal muscle, 12 young, healthy male subjects completed 7 days of bed rest with vastus lateralis muscle biopsies obtained before and after. In six of the subjects, muscle biopsies were taken from both...... than before bed rest. This bed rest-induced insulin resistance occurred together with reduced muscle GLUT4, hexokinase II, protein kinase B/Akt1, and Akt2 protein level, and a tendency for reduced 3-hydroxyacyl-CoA dehydrogenase activity. The ability of insulin to phosphorylate Akt and activate....... The present findings demonstrate that physical inactivity-induced insulin resistance in muscle is associated with lower content/activity of key proteins in glucose transport/phosphorylation and storage....

L-Cysteine supplementation increases adiponectin synthesis and secretion, and GLUT4 and glucose utilization by upregulating disulfide bond A-like protein expression mediated by MCP-1 inhibition in 3T3-L1 adipocytes exposed to high glucose.

Science.gov (United States)

Achari, Arunkumar Elumalai; Jain, Sushil K

2016-03-01

Adiponectin is an anti-diabetic and anti-atherogenic adipokine; its plasma levels are decreased in obesity, insulin resistance, and type 2 diabetes. An adiponectin-interacting protein named disulfide bond A-like protein (DsbA-L) plays an important role in the assembly of adiponectin. This study examined the hypothesis that L-cysteine (LC) regulates glucose homeostasis through the DsbA-L upregulation and synthesis and secretion of adiponectin in diabetes. 3T3L1 adipocytes were treated with LC (250 and 500 µM, 2 h) and high glucose (HG, 25 mM, 20 h). Results showed that LC supplementation significantly (p L, adiponectin, and GLUT-4 protein expression and glucose utilization in HG-treated adipocytes. LC supplementation significantly (p L expression and adiponectin levels in 3T3-L1 cells. Treatment with LC prevented the decrease in DsbA-L, adiponectin, and GLUT-4 expression in 3T3L1 adipocyte cells exposed to MCP-1. Thus, this study demonstrates that DsbA-L and adiponectin upregulation mediates the beneficial effects of LC on glucose utilization by inhibiting MCP-1 secretion in adipocytes and provides a novel mechanism by which LC supplementation can improve insulin sensitivity in diabetes.

Metformin ameliorates diabetes but does not normalize the decreased GLUT 4 content in skeletal muscle of obese (fa/fa) Zucker rats

DEFF Research Database (Denmark)

Handberg, A; Kayser, L; Høyer, P E

1993-01-01

We studied the expression of the glucose transporter GLUT 4 in the soleus and red gastrocnemius muscles from obese, diabetic (fa/fa) Zucker rats compared to their lean littermates (Fa/-), with and without treatment with the antidiabetic drug metformin. In the untreated groups of rats, the GLUT 4...... content in a crude membrane fraction of both the soleus and the red gastrocnemius muscles were significantly lower in the obese (fa/fa) rats (3.46 +/- 0.28 vs. 6.04 +/- 0.41, p ... the same rats were confirmed by quantitative immunofluorescence microscopy, and the results were significantly correlated with the results obtained from quantitative immunoblotting (rho = 0.70, p fa/fa rats could contribute to the well-established insulin...

PI3K-GLUT4 Signal Pathway Associated with Effects of EX-B3 Electroacupuncture on Hyperglycemia and Insulin Resistance of T2DM Rats

Directory of Open Access Journals (Sweden)

Bing-Yan Cao

2016-01-01

Full Text Available Objectives. To explore electroacupuncture’s (EA’s effects on fasting blood glucose (FBG and insulin resistance of type 2 diabetic mellitus (T2DM model rats and give a possible explanation for the effects. Method. It takes high fat diet and intraperitoneal injection of streptozotocin (STZ, 30 mg/kg for model preparation. Model rats were randomly divided into T2DM Model group, EA weiwanxiashu (EX-B3 group, and sham EA group (n=12/group. EA (2 Hz continuous wave, 2 mA, 20 min/day, 6 days/week, 4 weeks was applied as intervention. FBG, area under curve (AUC of oral glucose tolerance test (OGTT, insulin resistance index (HOMA-IR, pancreatic B cell function index (HOMA-B, skeletal muscle phosphorylated phosphatidylinositol-3-kinase (PI3K, glucose transporter 4 (GLUT4, and membrane GLUT4 protein expression were measured. Results. EA weiwanxiashu (EX-B3 can greatly upregulate model rat’s significantly reduced skeletal muscle PI3K (Y607 and membrane GLUT4 protein expression (P<0.01, effectively reducing model rats’ FBG and AUC of OGTT (P<0.01. The effects are far superior to sham EA group. Conclusion. EA weiwanxiashu (EX-B3 can upregulate skeletal muscle phosphorylated PI3K protein expression, to stimulate membrane translocation of GLUT4 and thereby increase skeletal muscle glucose intake to treat T2DM.

Genistein induces estrogen-like effects in ovariectomized rats but fails to increase cardiac GLUT4 and oxidative stress.

Science.gov (United States)

Al-Nakkash, Layla; Markus, Brandon; Batia, Lyn; Prozialeck, Walter C; Broderick, Tom L

2010-12-01

This study aimed to determine whether a 2-week genistein treatment induced estrogen-like effects in ovariectomized (OVX) Sprague-Dawley rats, after 2 weeks of subcutaneous genistein injections (250 mg/kg of body weight/day). Uterine weight, uterine-to-body weight ratio, femur weight, and femur-to-body weight ratio were all significantly increased with genistein in OVX rats. Body weight was significantly decreased with genistein in OVX rats. Genistein had no effect on the weights of heart, heart-to-body ratio, and fat pad but significantly decreased heart rate and pulse pressure. Genistein had no effect on cardiac GLUT4 protein, oxidative stress, plasma glucose, nonesterified fatty acids, or low-density lipoprotein levels; however, plasma insulin levels were significantly increased. Our results show that a 2-week genistein treatment produced favorable estrogen-like effects on some physical and physiological characteristics in OVX rats. However, based on our experimental conditions, the effects of genistein were not associated with changes in cardiac GLUT4 or oxidative stress.

De-phosphorylation of TRα-1 by p44/42 MAPK inhibition enhances T3-mediated GLUT5 gene expression in the intestinal cell line Caco-2 cells

International Nuclear Information System (INIS)

Mochizuki, Kazuki; Sakaguchi, Naomi; Takabe, Satsuki; Goda, Toshinao

2007-01-01

Thyroid hormone and p44/42 MAPK inactivation are important in intestinal differentiation. We demonstrated not only that treatment with p44/42 MAPK inhibitor U0126 in intestinal cell line Caco-2 cells reduced the phosphorylation of serine and threonine residues of TRα-1, but also that T 3 and U0126 synergistically induced GLUT5 gene expression. EMSA demonstrated that the binding activity of TRα-1-RXR heterodimer on GLUT5-TRE in nuclear proteins of Caco-2 cells was synergistically enhanced by co-incubation in vitro with T 3 and CIAP, which strongly de-phosphorylates proteins. ChIP and transfection assays revealed that co-treatment of T 3 and U0126 induces TRα-1-RXR binding to GLUT5-TRE on the human GLUT5 enhancer region, and recruitment of the transcriptional complex in cells. These results suggest that inactivation of p44/42 MAPK enhances T 3 -induced GLUT5 gene expression in Caco-2 cells through increasing TRα-1 transactivity and binding activity to the GLUT5-TRE, probably due to de-phosphorylation of TRα-1

Upregulation of Glucose Uptake and Hexokinase Activity of Primary Human CD4+ T Cells in Response to Infection with HIV-1

Directory of Open Access Journals (Sweden)

Maia Kavanagh Williamson

2018-03-01

Full Text Available Infection of primary CD4+ T cells with HIV-1 coincides with an increase in glycolysis. We investigated the expression of glucose transporters (GLUT and glycolytic enzymes in human CD4+ T cells in response to infection with HIV-1. We demonstrate the co-expression of GLUT1, GLUT3, GLUT4, and GLUT6 in human CD4+ T cells after activation, and their concerted overexpression in HIV-1 infected cells. The investigation of glycolytic enzymes demonstrated activation-dependent expression of hexokinases HK1 and HK2 in human CD4+ T cells, and a highly significant increase in cellular hexokinase enzyme activity in response to infection with HIV-1. HIV-1 infected CD4+ T cells showed a marked increase in expression of HK1, as well as the functionally related voltage-dependent anion channel (VDAC protein, but not HK2. The elevation of GLUT, HK1, and VDAC expression in HIV-1 infected cells mirrored replication kinetics and was dependent on virus replication, as evidenced by the use of reverse transcription inhibitors. Finally, we demonstrated that the upregulation of HK1 in HIV-1 infected CD4+ T cells is independent of the viral accessory proteins Vpu, Vif, Nef, and Vpr. Though these data are consistent with HIV-1 dependency on CD4+ T cell glucose metabolism, a cellular response mechanism to infection cannot be ruled out.

Associations Between PET Textural Features and GLUT1 Expression, and the Prognostic Significance of Textural Features in Lung Adenocarcinoma.

Science.gov (United States)

Koh, Young Wha; Park, Seong Yong; Hyun, Seung Hyup; Lee, Su Jin

2018-02-01

We evaluated the association between positron emission tomography (PET) textural features and glucose transporter 1 (GLUT1) expression level and further investigated the prognostic significance of textural features in lung adenocarcinoma. We evaluated 105 adenocarcinoma patients. We extracted texture-based PET parameters of primary tumors. Conventional PET parameters were also measured. The relationships between PET parameters and GLUT1 expression levels were evaluated. The association between PET parameters and overall survival (OS) was assessed using Cox's proportional hazard regression models. In terms of PET textural features, tumors expressing high levels of GLUT1 exhibited significantly lower coarseness, contrast, complexity, and strength, but significantly higher busyness. On univariate analysis, the metabolic tumor volume, total lesion glycolysis, contrast, busyness, complexity, and strength were significant predictors of OS. Multivariate analysis showed that lower complexity (HR=2.017, 95%CI=1.032-3.942, p=0.040) was independently associated with poorer survival. PET textural features may aid risk stratification in lung adenocarcinoma patients. Copyright© 2018, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.

Insulin stimulates translocation of human GLUT4 to the membrane in fat bodies of transgenic Drosophila melanogaster.

Directory of Open Access Journals (Sweden)

Georgeta Crivat

Full Text Available The fruit fly Drosophila melanogaster is an excellent model system for studies of genes controlling development and disease. However, its applicability to physiological systems is less clear because of metabolic differences between insects and mammals. Insulin signaling has been studied in mammals because of relevance to diabetes and other diseases but there are many parallels between mammalian and insect pathways. For example, deletion of Drosophila Insulin-Like Peptides resulted in 'diabetic' flies with elevated circulating sugar levels. Whether this situation reflects failure of sugar uptake into peripheral tissues as seen in mammals is unclear and depends upon whether flies harbor the machinery to mount mammalian-like insulin-dependent sugar uptake responses. Here we asked whether Drosophila fat cells are competent to respond to insulin with mammalian-like regulated trafficking of sugar transporters. Transgenic Drosophila expressing human glucose transporter-4 (GLUT4, the sugar transporter expressed primarily in insulin-responsive tissues, were generated. After expression in fat bodies, GLUT4 intracellular trafficking and localization were monitored by confocal and total internal reflection fluorescence microscopy (TIRFM. We found that fat body cells responded to insulin with increased GLUT4 trafficking and translocation to the plasma membrane. While the amplitude of these responses was relatively weak in animals reared on a standard diet, it was greatly enhanced in animals reared on sugar-restricted diets, suggesting that flies fed standard diets are insulin resistant. Our findings demonstrate that flies are competent to mobilize translocation of sugar transporters to the cell surface in response to insulin. They suggest that Drosophila fat cells are primed for a response to insulin and that these pathways are down-regulated when animals are exposed to constant, high levels of sugar. Finally, these studies are the first to use TIRFM to

Insulin Stimulates Translocation of Human GLUT4 to the Membrane in Fat Bodies of Transgenic Drosophila melanogaster

Science.gov (United States)

Crivat, Georgeta; Lizunov, Vladimir A.; Li, Caroline R.; Stenkula, Karin G.; Zimmerberg, Joshua; Cushman, Samuel W.; Pick, Leslie

2013-01-01

The fruit fly Drosophila melanogaster is an excellent model system for studies of genes controlling development and disease. However, its applicability to physiological systems is less clear because of metabolic differences between insects and mammals. Insulin signaling has been studied in mammals because of relevance to diabetes and other diseases but there are many parallels between mammalian and insect pathways. For example, deletion of Drosophila Insulin-Like Peptides resulted in ‘diabetic’ flies with elevated circulating sugar levels. Whether this situation reflects failure of sugar uptake into peripheral tissues as seen in mammals is unclear and depends upon whether flies harbor the machinery to mount mammalian-like insulin-dependent sugar uptake responses. Here we asked whether Drosophila fat cells are competent to respond to insulin with mammalian-like regulated trafficking of sugar transporters. Transgenic Drosophila expressing human glucose transporter-4 (GLUT4), the sugar transporter expressed primarily in insulin-responsive tissues, were generated. After expression in fat bodies, GLUT4 intracellular trafficking and localization were monitored by confocal and total internal reflection fluorescence microscopy (TIRFM). We found that fat body cells responded to insulin with increased GLUT4 trafficking and translocation to the plasma membrane. While the amplitude of these responses was relatively weak in animals reared on a standard diet, it was greatly enhanced in animals reared on sugar-restricted diets, suggesting that flies fed standard diets are insulin resistant. Our findings demonstrate that flies are competent to mobilize translocation of sugar transporters to the cell surface in response to insulin. They suggest that Drosophila fat cells are primed for a response to insulin and that these pathways are down-regulated when animals are exposed to constant, high levels of sugar. Finally, these studies are the first to use TIRFM to monitor insulin

Caveolin-1 and glucose transporter 4 involved in the regulation of glucose-deprivation stress in PC12 cells.

Science.gov (United States)

Zhang, Qi-Qi; Huang, Liang; Han, Chao; Guan, Xin; Wang, Ya-Jun; Liu, Jing; Wan, Jing-Hua; Zou, Wei

2015-08-25

Recent evidence suggests that caveolin-1 (Cav-1), the major protein constituent of caveolae, plays a prominent role in neuronal nutritional availability with cellular fate regulation besides in several cellular processes such as cholesterol homeostasis, regulation of signal transduction, integrin signaling and cell growth. Here, we aimed to investigate the function of Cav-1 and glucose transporter 4 (GLUT4) upon glucose deprivation (GD) in PC12 cells. The results demonstrated firstly that both Cav-1 and GLUT4 were up-regulated by glucose withdrawal in PC12 cells by using Western blot and laser confocal technology. Also, we found that the cell death rate, mitochondrial membrane potential (MMP) and intracellular free Ca(2+) concentration ([Ca(2+)]i) were also respectively changed followed the GD stress tested by CCK8 and flow cytometry. After knocking down of Cav-1 in the cells by siRNA, the level of [Ca(2+)]i was increased, and MMP was reduced further in GD-treated PC12 cells. Knockdown of Cav-1 or methylated-β-Cyclodextrin (M-β-CD) treatment inhibited the expression of GLUT4 protein upon GD. Additionally, we found that GLUT4 could translocate from cytoplasm to cell membrane upon GD. These findings might suggest a neuroprotective role for Cav-1, through coordination of GLUT4 in GD.

GLUT1 deficiency syndrome as a cause of encephalopathy that includes cognitive disability, treatment-resistant infantile epilepsy and a complex movement disorder.

Science.gov (United States)

Graham, John M

2012-05-01

Glucose transporter-1 (GLUT1) deficiency syndrome is caused by heterozygous mutations in the SLC2A1 gene, resulting in impaired glucose transport into the brain. It is characterized by a low glucose concentration in the cerebrospinal fluid (hypoglycorrhachia) in the absence of hypoglycemia, in combination with low to normal lactate in the cerebrospinal fluid (CSF). It often results in treatment-resistant infantile epilepsy with progressive developmental disabilities and a complex movement disorder. Recognizing GLUT1 deficiency syndrome is important, since initiation of a ketogenic diet can reduce the frequency of seizures and the severity of the movement disorder. There can be a considerable delay in diagnosing GLUT1 deficiency syndrome, and this point is illustrated by the natural history of this disorder in a 21-year-old woman with severe, progressive neurological disabilities. Her encephalopathy consisted of treatment-resistant seizures, a complex movement disorder, progressive intellectual disability, and deceleration of her head growth after late infancy. Focused evaluation at age 21 revealed GLUT1 deficiency caused by a novel heterozygous missence mutation in exon 7 (c.938C > A; p.Ser313Try) in SLC2A1 as the cause for her disabilities. Copyright © 2011 Elsevier Masson SAS. All rights reserved.

[6]-Gingerol, from Zingiber officinale, potentiates GLP-1 mediated glucose-stimulated insulin secretion pathway in pancreatic β-cells and increases RAB8/RAB10-regulated membrane presentation of GLUT4 transporters in skeletal muscle to improve hyperglycemia in Leprdb/db type 2 diabetic mice.

Science.gov (United States)

Samad, Mehdi Bin; Mohsin, Md Nurul Absar Bin; Razu, Bodiul Alam; Hossain, Mohammad Tashnim; Mahzabeen, Sinayat; Unnoor, Naziat; Muna, Ishrat Aklima; Akhter, Farjana; Kabir, Ashraf Ul; Hannan, J M A

2017-08-09

[6]-Gingerol, a major component of Zingiber officinale, was previously reported to ameliorate hyperglycemia in type 2 diabetic mice. Endocrine signaling is involved in insulin secretion and is perturbed in db/db Type-2 diabetic mice. [6]-Gingerol was reported to restore the disrupted endocrine signaling in rodents. In this current study on Lepr db/db diabetic mice, we investigated the involvement of endocrine pathway in the insulin secretagogue activity of [6]-Gingerol and the mechanism(s) through which [6]-Gingerol ameliorates hyperglycemia. Lepr db/db type 2 diabetic mice were orally administered a daily dose of [6]-Gingerol (200 mg/kg) for 28 days. We measured the plasma levels of different endocrine hormones in fasting and fed conditions. GLP-1 levels were modulated using pharmacological approaches, and cAMP/PKA pathway for insulin secretion was assessed by qRT-PCR and ELISA in isolated pancreatic islets. Total skeletal muscle and its membrane fractions were used to measure glycogen synthase 1 level and Glut4 expression and protein levels. 4-weeks treatment of [6]-Gingerol dramatically increased glucose-stimulated insulin secretion and improved glucose tolerance. Plasma GLP-1 was found to be significantly elevated in the treated mice. Pharmacological intervention of GLP-1 levels regulated the effect of [6]-Gingerol on insulin secretion. Mechanistically, [6]-Gingerol treatment upregulated and activated cAMP, PKA, and CREB in the pancreatic islets, which are critical components of GLP-1-mediated insulin secretion pathway. [6]-Gingerol upregulated both Rab27a GTPase and its effector protein Slp4-a expression in isolated islets, which regulates the exocytosis of insulin-containing dense-core granules. [6]-Gingerol treatment improved skeletal glycogen storage by increased glycogen synthase 1 activity. Additionally, GLUT4 transporters were highly abundant in the membrane of the skeletal myocytes, which could be explained by the increased expression of Rab8 and Rab

Diabetic microvascular complications are not associated with two polymorphisms in the GLUT-1 and PC-1 genes regulating glucose metabolism in Caucasian type 1 diabetic patients

DEFF Research Database (Denmark)

Tarnow, L; Grarup, N; Hansen, T

2001-01-01

BACKGROUND: An XbaI polymorphism in the gene encoding the glucose transporter, GLUT-1, is associated with development of diabetic nephropathy in Chinese type 2 diabetic patients. In addition, an amino acid variant (K121Q) in the gene encoding the glycoprotein plasma cell differentiating antigen (PC...... men/77 women, age 40.9+/-9.6 years, diabetes duration 27+/-8 years) and type 1 diabetic patients with persistent normoalbuminuria (118 men/74 women, age 42.7+/-10.2 years, diabetes duration 26+/-9 years). Proliferative retinopathy was present in 156 patients (40%), while 67 patients (17%) had....... CONCLUSIONS: Neither the PC-1 K121Q nor the GLUT-1 XbaI polymorphism contribute to the genetic susceptibility of diabetic microvascular complications in Danish type 1 diabetic patients....

Sex-Specific Life Course Changes in the Neuro-Metabolic Phenotype of Glut3 Null Heterozygous Mice: Ketogenic Diet Ameliorates Electroencephalographic Seizures and Improves Sociability.

Science.gov (United States)

Dai, Yun; Zhao, Yuanzi; Tomi, Masatoshi; Shin, Bo-Chul; Thamotharan, Shanthie; Mazarati, Andrey; Sankar, Raman; Wang, Elizabeth A; Cepeda, Carlos; Levine, Michael S; Zhang, Jingjing; Frew, Andrew; Alger, Jeffry R; Clark, Peter M; Sondhi, Monica; Kositamongkol, Sudatip; Leibovitch, Leah; Devaskar, Sherin U

2017-04-01

We tested the hypothesis that exposure of glut3+/- mice to a ketogenic diet ameliorates autism-like features, which include aberrant behavior and electrographic seizures. We first investigated the life course sex-specific changes in basal plasma-cerebrospinal fluid (CSF)-brain metabolic profile, brain glucose transport/uptake, glucose and monocarboxylate transporter proteins, and adenosine triphosphate (ATP) in the presence or absence of systemic insulin administration. Glut3+/- male but not female mice (5 months of age) displayed reduced CSF glucose/lactate concentrations with no change in brain Glut1, Mct2, glucose uptake or ATP. Exogenous insulin-induced hypoglycemia increased brain glucose uptake in glut3+/- males alone. Higher plasma-CSF ketones (β-hydroxybutyrate) and lower brain Glut3 in females vs males proved protective in the former while enhancing vulnerability in the latter. As a consequence, increased synaptic proteins (neuroligin4 and SAPAP1) with spontaneous excitatory postsynaptic activity subsequently reduced hippocampal glucose content and increased brain amyloid β1-40 deposition in an age-dependent manner in glut3+/- males but not females (4 to 24 months of age). We then explored the protective effect of a ketogenic diet on ultrasonic vocalization, sociability, spatial learning and memory, and electroencephalogram seizures in male mice (7 days to 6 to 8 months of age) alone. A ketogenic diet partially restored sociability without affecting perturbed vocalization, spatial learning and memory, and reduced seizure events. We conclude that (1) sex-specific and age-dependent perturbations underlie the phenotype of glut3+/- mice, and (2) a ketogenic diet ameliorates seizures caused by increased cortical excitation and improves sociability, but fails to rescue vocalization and cognitive deficits in glut3+/- male mice. Copyright © 2017 Endocrine Society.

GLUT2 and the incretin receptors are involved in glucose-induced incretin secretion

DEFF Research Database (Denmark)

Cani, Patrice D; Holst, Jens Juul; Drucker, Daniel J

2007-01-01

to those described for beta-cells, brain and hepatoportal sensors. We determined the role of GLUT2, GLP-1 or GIP receptors in glucose-induced incretins secretion, in the corresponding knockout mice. GLP-1 secretion was reduced in all mutant mice, while GIP secretion did not require GLUT2. Intestinal GLP-1...... content was reduced only in GIP and GLUT2 receptors knockout mice suggesting that this impairment could contribute to the phenotype. Intestinal GIP content was similar in all mice studied. Furthermore, the impaired incretins secretion was associated with a reduced glucose-stimulated insulin secretion...

Association of single nucleotide polymorphisms in the gene encoding GLUT1 and diabetic nephropathy in Brazilian patients with type 1 diabetes mellitus.

Science.gov (United States)

Marques, T; Patente, T A; Monteiro, M B; Cavaleiro, A M; Queiroz, M S; Nery, M; de Azevedo, M J; Canani, L H; Parisi, M C; Moura-Neto, A; Passarelli, M; Giannella-Neto, D; Machado, U F; Corrêa-Giannella, M L

2015-04-15

Mesangial cells subject to high extracellular glucose concentrations, as occur in hyperglycaemic states, are unable to down regulate glucose influx, resulting in intracellular activation of deleterious biochemical pathways. A high expression of GLUT1 participates in the development of diabetic glomerulopathy. Variants in the gene encoding GLUT1 (SLC2A1) have been associated to this diabetic complication. The aim of this study was to test whether polymorphisms in SLC2A1 confer susceptibility to diabetic nephropathy (DN) in Brazilian type 1 diabetes patients. Four polymorphisms (rs3820589, rs1385129, rs841847 and rs841848) were genotyped in a Brazilian cohort comprised of 452 patients. A prospective analysis was performed in 155 patients. Mean duration of follow-up was 5.6 ± 2.4 years and the incidence of renal events was 18.0%. The rs3820589 presented an inverse association with the prevalence of incipient DN (OR: 0.36, 95% CI: 0.16 - 0.80, p=0.01) and with progression to renal events (HR: 0.20; 95% CI: 0.03 - 0.70; p=0.009). AGGT and AGAC haplotypes were associated with the prevalence of incipient DN and the AGAC haplotype was also associated with the prevalence of established/advanced DN. In conclusion, rs3820589 in the SLC2A1 gene modulates the risk to DN in Brazilian patients with inadequate type 1 diabetes control. Copyright © 2015 Elsevier B.V. All rights reserved.

糖脂平对胰岛素抵抗大鼠 GLUT4表达的影响%Impact of Tangzhiping on GUIT4 Expression in the Rats of Insulin Resistance

Institute of Scientific and Technical Information of China (English)

刘静; 朱智耀; 高彦彬; 赵轩; 周盛楠; 李娇阳; 仝宇; 王晓磊

2016-01-01

Objective To observe the impacts of tangzhiping on GLUT4 expression of epicyte of skeletal muscle in the rats of insulin resistance induced by high - lipid diet. Methods Forty - eight male SD rats,weighted from 180 to 200 g were selected and randomized into a blank group(12 rats)and a modeling group(36 rats). In the blank group,the common forage was used. In the model group,the high - lipid forage was used. After successful modeling in 8 weeks,the rats in the modeling group was subdivided randomly into a mode group,a Chinese medicine group and a western medicine group,12 rats in each one. In the Chinese medicine group,tangzhiping was used for gavage,20 g/ kg a day. In the western medicine group,rosiglitazone was used for gavage,0. 8 mg/ kg a day. The physical saline of same dose was used for gavage in the model group and the blank group. The gavage lasted for 8 weeks continuously. After the last medication,fasting was done for 12 h. The euglycemic hyperinsulinemic clamp technique was performed to evaluate the insulin sensi-tivity(M value). Enzymatic detection was used to measure the levels of TC,TG,HDL - C and LDL - C. Western Blot was used to detect GLUT4 expression of epicyte of skeletal muscle. Results Compared with the blank group,the insulin sensitivity was apparently reduced,the levels of TC,TG and LDL - C were apparently increased,HDL - C and GLUT4 expression were apparently reduced in the model group. Compared with the model group,the insulin sensitivity was increased apparently,the levels of TG and LDL - C were reduced, GLUT4 expression was increased apparently in the Chinese medicine group. The changes in TC and HDL - C were not apparent. Conclusion Tangzhiping improves the insulin sensitivity and adjusts lipid metabolic dis-turbance in the rats of insulin resistance. The effect mechanism may be related to the improvement of GLUT4 expression in epicyte of skeletal muscle and enhancement of the absorption and utility of skeletal muscular tissue to glucose

Identification of a novel phosphorylation site on TBC1D4 regulated by AMP-activated protein kinase in skeletal muscle

DEFF Research Database (Denmark)

Treebak, Jonas Thue; Taylor, Eric B.; Witczak, Carol A.

2010-01-01

TBC1D4 (also known as AS160) regulates GLUT4 translocation and glucose uptake in adipocytes and skeletal muscle. Its mode of action involves phosphorylation of Serine (S)/Threonine (T) residues by upstream kinases resulting in inactivation of Rab-GAP activity leading to GLUT4 mobilization...

An increase in immature β-cells lacking Glut2 precedes the expansion of β-cell mass in the pregnant mouse.

Directory of Open Access Journals (Sweden)

Christine A Beamish

Full Text Available A compensatory increase in β-cell mass occurs during pregnancy to counter the associated insulin resistance, and a failure in adaptation is thought to contribute to gestational diabetes. Insulin-expressing but glucose-transporter-2-low (Ins+Glut2LO progenitor cells are present in mouse and human pancreas, being predominantly located in extra-islet β-cell clusters, and contribute to the regeneration of the endocrine pancreas following induced ablation. We therefore sought to investigate the contribution of Ins+Glut2LO cells to β-cell mass expansion during pregnancy. Female C57Bl/6 mice were time mated and pancreata were collected at gestational days (GD 6, 9, 12, 15, and 18, and postpartum D7 (n = 4/time-point and compared to control (non-pregnant animals. Beta cell mass, location, proliferation (Ki67+, and proportion of Ins+Glut2LO cells were measured using immunohistochemistry and bright field or confocal microscopy. Beta cell mass tripled by GD18 and β-cell proliferation peaked at GD12 in islets (≥6 β-cells and small β-cell clusters (1-5 β-cells. The proportion and fraction of Ins+Glut2LO cells undergoing proliferation increased significantly at GD9 in both islets and clusters, preceding the increase in β-cell mass and proliferation, and their proliferation within clusters persisted until GD15. The overall number of clusters increased significantly at GD9. Quantitative PCR showed a significant increase in Pdx1 presence at GD9 vs. GD18 or control pancreas, and Pdx1 was visualized by immunohistochemistry within both Ins+Glut2LO and Ins+Glut2HI cells within clusters. These results indicate that Ins+Glut2LO cells are likely to contribute to β-cell mass expansion during pregnancy.

CD63 and GLUT-1 Overexpression Could Predict a Poor Clinical Outcome in GIST: A Study of 54 Cases with Follow-Up

Directory of Open Access Journals (Sweden)

Piotr Lewitowicz

2016-01-01

Full Text Available Background and Goals. In light of current knowledge, it seems that alternations underlying GISTs are well explained, although all that is enhanced by various aspects on a daily basis. More recently, attention has been pointed towards exosomes as important particles able to modify healthy and also diseased tissues including cancer. The goal of the present study was an analysis of CD9, CD63, and GLUT-1 as a marker of hypoxia status within 54 cases of GIST and evaluation of their predictive value. Methods. 54 cases of patients suffering from GIST were enrolled into the study, predominantly in the gastric location. All operated cases had no Imatinib and other chemotherapies up to the day of operation. Expression of targeted proteins was performed by immunohistochemistry and, after that, the results with tabulated clinical data were compared by Kaplan-Meier method and multivariate Cox proportional hazard model of statistical analysis. Results. Our results presented a marked dependence of worsening clinical outcome with high expression CD63 (p=0.008 as well as with GLUT-1 (p=0.014. We noted a strict correlation of GLUT-1 expression with CD63 expression (p=0.03, which could confirm the thesis about the contribution of exosomes in intratumoural hypoxia status. The collected material did not confirm CD9 contribution. Conclusions. As presented here, CD63 and GLUT-1 have a prognostic value in GIST cases. The results confirm the other studies in this scope and can be used in future as an additional prognostic factor.

Attenuation of insulin resistance in rats by agmatine: role of SREBP-1c, mTOR and GLUT-2.

Science.gov (United States)

Sharawy, Maha H; El-Awady, Mohammed S; Megahed, Nirmeen; Gameil, Nariman M

2016-01-01

Insulin resistance is a serious health condition worldwide; however, its exact mechanisms are still unclear. This study investigates agmatine (AGM; an endogenous metabolite of L-arginine) effects on insulin resistance induced by high fructose diet (HFD) in rats and the possible involved mechanisms. Sprague Dawley rats were fed 60% HFD for 12 weeks, and AGM (10 mg/kg/day, orally) was given from week 9 to 12. AGM significantly reduced HFD-induced elevation in fasting insulin level, homeostasis model assessment of insulin resistance (HOMA-IR) index and liver glycogen content from 3.44-, 3.62- and 2.07- to 2.59-, 2.78- and 1.3-fold, respectively, compared to the control group, while it increased HFD-induced reduction in glucose tolerance. Additionally, AGM significantly decreased HFD-induced elevation in serum triglycerides, low density lipoprotein cholesterol and very low density lipoprotein cholesterol levels from 3.18-, 2.97- and 4.75- to 1.25-, 1.25- and 1.07-fold, respectively, compared to control group. Conversely, AGM had no significant effect on HFD-induced changes in fasting glucose, glycosylated hemoglobin, insulin tolerance and high density lipoprotein cholesterol. Furthermore, AGM significantly reduced HFD-induced elevation in mRNA expression of glucose transporter type-2 (GLUT-2), mammalian target of rapamycin (mTOR) and sterol regulatory element-binding protein-1c (SREBP-1c) without affecting that of peroxisome proliferator-activated receptor-alpha (PPAR-α) in the liver. Additionally, AGM enhanced ACh-induced aortic relaxation and attenuated liver steatosis induced by HFD. In conclusion, AGM may have a therapeutic potential in insulin resistance through suppressing SREBP-1c, mTOR and GLUT-2 in liver.

GLUT3 gene expression is critical for embryonic growth, brain development and survival.

Science.gov (United States)

Carayannopoulos, Mary O; Xiong, Fuxia; Jensen, Penny; Rios-Galdamez, Yesenia; Huang, Haigen; Lin, Shuo; Devaskar, Sherin U

2014-04-01

Glucose is the primary energy source for eukaryotic cells and the predominant substrate for the brain. GLUT3 is essential for trans-placental glucose transport and highly expressed in the mammalian brain. To further elucidate the role of GLUT3 in embryonic development, we utilized the vertebrate whole animal model system of Danio rerio as a tractable system for defining the cellular and molecular mechanisms altered by impaired glucose transport and metabolism related to perturbed expression of GLUT3. The comparable orthologue of human GLUT3 was identified and the expression of this gene abrogated during early embryonic development. In a dose-dependent manner embryonic brain development was disrupted resulting in a phenotype of aberrant brain organogenesis, associated with embryonic growth restriction and increased cellular apoptosis. Rescue of the morphant phenotype was achieved by providing exogenous GLUT3 mRNA. We conclude that GLUT3 is critically important for brain organogenesis and embryonic growth. Disruption of GLUT3 is responsible for the phenotypic spectrum of embryonic growth restriction to demise and neural apoptosis with microcephaly. Copyright © 2014 Elsevier Inc. All rights reserved.

A Glimpse of Membrane Transport through Structures-Advances in the Structural Biology of the GLUT Glucose Transporters.

Science.gov (United States)

Yan, Nieng

2017-08-18

The cellular uptake of glucose is an essential physiological process, and movement of glucose across biological membranes requires specialized transporters. The major facilitator superfamily glucose transporters GLUTs, encoded by the SLC2A genes, have been a paradigm for functional, mechanistic, and structural understanding of solute transport in the past century. This review starts with a glimpse into the structural biology of membrane proteins and particularly membrane transport proteins, enumerating the landmark structures in the past 25years. The recent breakthrough in the structural elucidation of GLUTs is then elaborated following a brief overview of the research history of these archetypal transporters, their functional specificity, and physiological and pathophysiological significances. Structures of GLUT1, GLUT3, and GLUT5 in distinct transport and/or ligand-binding states reveal detailed mechanisms of the alternating access transport cycle and substrate recognition, and thus illuminate a path by which structure-based drug design may be applied to help discover novel therapeutics against several debilitating human diseases associated with GLUT malfunction and/or misregulation. Copyright © 2017 Elsevier Ltd. All rights reserved.

The role of SLC2A1 mutations in myoclonic astatic epilepsy and absence epilepsy, and the estimated frequency of GLUT1 deficiency syndrome

DEFF Research Database (Denmark)

Larsen, Jan; Johannesen, Katrine Marie; Ek, Jakob

2015-01-01

The first mutations identified in SLC2A1, encoding the glucose transporter type 1 (GLUT1) protein of the blood-brain barrier, were associated with severe epileptic encephalopathy. Recently, dominant SLC2A1 mutations were found in rare autosomal dominant families with various forms of epilepsy inc...

Neonatal hypothyroidism affects testicular glucose homeostasis through increased oxidative stress in prepubertal mice: effects on GLUT3, GLUT8 and Cx43.

Science.gov (United States)

Sarkar, D; Singh, S K

2017-07-01

Thyroid hormones (THs) play an important role in maintaining the link between metabolism and reproduction and the altered THs status is associated with induction of oxidative stress in various organs like brain, heart, liver and testis. Further, reactive oxygen species play a pivotal role in regulation of glucose homeostasis in several organs, and glucose utilization by Leydig cells is essential for testosterone biosynthesis and thus is largely dependent on glucose transporter 8 (GLUT8). Glucose uptake by Sertoli cells is mediated through glucose transporter 3 (GLUT3) under the influence of THs to meet energy requirement of developing germ cells. THs also modulate level of gap junctional protein such as connexin 43 (Cx43), a potential regulator of cell proliferation and apoptosis in the seminiferous epithelium. Although the role of transient neonatal hypothyroidism in adult testis in terms of testosterone production is well documented, the effect of THs deficiency in early developmental period and its role in testicular glucose homeostasis and oxidative stress with reference to Cx43 in immature mice remain unknown. Therefore, the present study was conducted to evaluate the effect of neonatal hypothyroidism on testicular glucose homeostasis and oxidative stress at postnatal days (PND) 21 and 28 in relation to GLUT3, GLUT8 and Cx43. Hypothyroidism induced by 6-propyl-2-thiouracil (PTU) markedly decreased testicular glucose level with considerable reduction in expression level of GLUT3 and GLUT8. Likewise, lactate dehydrogenase (LDH) activity and intratesticular concentration of lactate were also decreased in hypothyroid mice. There was also a rise in germ cell apoptosis with increased expression of caspase-3 in PTU-treated mice. Further, neonatal hypothyroidism affected germ cell proliferation with decreased expression of proliferating cell nuclear antigen (PCNA) and Cx43. In conclusion, our results suggest that neonatal hypothyroidism alters testicular glucose

27-Hydroxycholesterol impairs neuronal glucose uptake through an IRAP/GLUT4 system dysregulation

Science.gov (United States)

Mateos, Laura; Maioli, Silvia; Ali, Zeina; Gulyás, Balázs; Winblad, Bengt; Savitcheva, Irina

2017-01-01

Hypercholesterolemia is associated with cognitively deteriorated states. Here, we show that excess 27-hydroxycholesterol (27-OH), a cholesterol metabolite passing from the circulation into the brain, reduced in vivo brain glucose uptake, GLUT4 expression, and spatial memory. Furthermore, patients exhibiting higher 27-OH levels had reduced 18F-fluorodeoxyglucose uptake. This interplay between 27-OH and glucose uptake revealed the engagement of the insulin-regulated aminopeptidase (IRAP). 27-OH increased the levels and activity of IRAP, countered the IRAP antagonist angiotensin IV (AngIV)–mediated glucose uptake, and enhanced the levels of the AngIV-degrading enzyme aminopeptidase N (AP-N). These effects were mediated by liver X receptors. Our results reveal a molecular link between cholesterol, brain glucose, and the brain renin-angiotensin system, all of which are affected in some neurodegenerative diseases. Thus, reducing 27-OH levels or inhibiting AP-N maybe a useful strategy in the prevention of the altered glucose metabolism and memory decline in these disorders. PMID:28213512

The ergogenic supplement β-hydroxy-β-methylbutyrate (HMB) attenuates insulin resistance through suppressing GLUT-2 in rat liver.

Science.gov (United States)

Sharawy, Maha H; El-Awady, Mohammed S; Megahed, Nirmeen; Gameil, Nariman M

2016-05-01

This study investigates the effect of the ergogenic supplement β-hydroxy-β-methylbutyrate (HMB) on insulin resistance induced by high-fructose diet (HFD) in rats. Male Sprague Dawley rats were fed 60% HFD for 12 weeks and HMB (320 mg·kg(-1)·day(-1), orally) for 4 weeks. HFD significantly increased fasting insulin, fasting glucose, glycosylated hemoglobin (HBA1C), liver glycogen content, and homeostasis model assessment of insulin resistance (HOMA-IR) index, while it decreased glucose and insulin tolerance. Furthermore, HFD significantly increased serum triglycerides (TG), low density lipoprotein cholesterol (LDL-C), and very low density lipoprotein cholesterol (VLDL-C) levels, while it significantly decreased high density lipoprotein cholesterol (HDL-C). Moreover, HFD significantly increased mRNA expression of glucose transporter type-2 (GLUT-2), the mammalian target of rapamycin (mTOR), and sterol regulatory element-binding protein-1c (SREBP-1c) but decreased peroxisome proliferator-activated receptor-alpha (PPAR-α) in liver. Aortic relaxation to acetylcholine (ACh) was impaired and histopathology showed severe hepatic steatosis. HMB significantly increased insulin tolerance and decreased fasting insulin, HOMA-IR, HBA1C, hepatic glycogen content, serum TG, LDL-C, and VLDL-C. Additionally, HMB enhanced ACh-induced relaxation, ameliorated hepatic steatosis, and decreased mRNA expression of GLUT-2. In conclusion, HMB may attenuate insulin resistance and hepatic steatosis through inhibiting GLUT-2 in liver.

12038_2016_9616_Supplementary 1..4

Indian Academy of Sciences (India)

homeostasis, autoimmunity, responses to infection, cancers and inflammation. ... CD40+CD4+T cells involved in type-I diabetes through binding of Gal-9 with CD40. ... ForssmanGlycosphingolipid; FOXP3: Forkhead Box P3; GLUT 2: Glucose.

Novel Roles for the Insulin-Regulated Glucose Transporter-4 in Hippocampally Dependent Memory.

Science.gov (United States)

Pearson-Leary, Jiah; McNay, Ewan C

2016-11-23

The insulin-regulated glucose transporter-4 (GluT4) is critical for insulin- and contractile-mediated glucose uptake in skeletal muscle. GluT4 is also expressed in some hippocampal neurons, but its functional role in the brain is unclear. Several established molecular modulators of memory processing regulate hippocampal GluT4 trafficking and hippocampal memory formation is limited by both glucose metabolism and insulin signaling. Therefore, we hypothesized that hippocampal GluT4 might be involved in memory processes. Here, we show that, in male rats, hippocampal GluT4 translocates to the plasma membrane after memory training and that acute, selective intrahippocampal inhibition of GluT4-mediated glucose transport impaired memory acquisition, but not memory retrieval. Other studies have shown that prolonged systemic GluT4 blockade causes insulin resistance. Unexpectedly, we found that prolonged hippocampal blockade of glucose transport through GluT4-upregulated markers of hippocampal insulin signaling prevented task-associated depletion of hippocampal glucose and enhanced both working and short-term memory while also impairing long-term memory. These effects were accompanied by increased expression of hippocampal AMPA GluR1 subunits and the neuronal GluT3, but decreased expression of hippocampal brain-derived neurotrophic factor, consistent with impaired ability to form long-term memories. Our findings are the first to show the cognitive impact of brain GluT4 modulation. They identify GluT4 as a key regulator of hippocampal memory processing and also suggest differential regulation of GluT4 in the hippocampus from that in peripheral tissues. The role of insulin-regulated glucose transporter-4 (GluT4) in the brain is unclear. In the current study, we demonstrate that GluT4 is a critical component of hippocampal memory processes. Memory training increased hippocampal GluT4 translocation and memory acquisition was impaired by GluT4 blockade. Unexpectedly, whereas long

GLUT1-mediated selective tumor targeting with fluorine containing platinum(II) glycoconjugates

OpenAIRE

Liu, Ran; Fu, Zheng; Zhao, Meng; Gao, Xiangqian; Li, Hong; Mi, Qian; Liu, Pengxing; Yang, Jinna; Yao, Zhi; Gao, Qingzhi

2017-01-01

Increased glycolysis and overexpression of glucose transporters (GLUTs) are physiological characteristics of human malignancies. Based on the so-called Warburg effect, 18flurodeoxyglucose-positron emission tomography (FDG-PET) has successfully developed as clinical modality for the diagnosis and staging of many cancers. To leverage this glucose transporter mediated metabolic disparity between normal and malignant cells, in the current report, we focus on the fluorine substituted series of glu...

Hypouricemic Effects of Ganoderma applanatum in Hyperuricemia Mice through OAT1 and GLUT9

Directory of Open Access Journals (Sweden)

Tianqiao Yong

2018-01-01

Full Text Available Ganoderma applanatum (G. applanatum dispels wind to eliminate dampness and exhibited nephron- and liver-protective effects as noted in Chinese herbal classic literature; it might also affect hyperuricemia. Therefore, we examined the hypouricemia effects and mechanisms underlying G. applanatum on chemical-induced hyperuricemia in mice. Ethanol (GAE and water (GAW extracts were prepared by extracting G. applanatum in ethanol (GAE, followed by bathing the remains in water to yield GAW. GAE and GAW were administered orally at different doses to hyperuricemia mice, while allopurinol and benzbromarone served as positive controls. Both GAE and GAW showed remarkable hypouricemia activities, rendering a substantial decline in the SUA (serum uric acid level in hyperuricemia control (P < 0.01. Moreover, the urine uric acid (UUA levels were enhanced by GAE and GAW. In contrast to the evident renal toxicity of allopurinol, GAE and GAW did not show a distinct renal toxicity. Almost no suppressing effect was observed on the XOD activities. However, compared to the hyperuricemia control, OAT1 was elevated remarkably in mice drugged with GAE and GAW, while GLUT9 was significantly decreased. Similar to benzbromarone, GAE decreased the URAT1 protein levels significantly (P < 0.01, while GAW did not display a similar effect. GAE and GAW downregulated the level of CNT2 proteins in the gastrointestinal tract of hyperuricemia mice. Thus, G. applanatum produced outstanding hypouricemic effects, mediated by renal OAT1, GLUT9, and URAT1 and gastrointestinal CNT2 that might elevate urine uric secretions and decline in the absorption of purine in the gastrointestinal tracts. G. applanatum showed little negative influence on inner organs. By docking screening, four top-ranked compounds were identified that necessitated further investigation.Compounds: potassium oxonate, hypoxanthine, allopurinol, benzbromarone.

Activation of nuclear receptor NR5A2 increases Glut4 expression and glucose metabolism in muscle cells

Energy Technology Data Exchange (ETDEWEB)

Bolado-Carrancio, A. [Department of Molecular Biology, University of Cantabria, IDIVAL, Santander (Spain); Riancho, J.A. [Department of Internal Medicine, Hospital U.M. Valdecilla-IDIVAL, University of Cantabria, RETICEF, Santander (Spain); Sainz, J. [Institute of Biomedicine and Biotechnology of Cantabria (IBBTEC), CSIC-University of Cantabria, Santander (Spain); Rodríguez-Rey, J.C., E-mail: rodriguj@unican.es [Department of Molecular Biology, University of Cantabria, IDIVAL, Santander (Spain)

2014-04-04

Highlights: • NR5A2 expression in C2C12 is associated with myotube differentiation. • DLPC induces an increase in GLUT4 levels and glucose uptake in C2C12 myotubes. • In high glucose conditions the activation of NR5A2 inhibits fatty acids oxidation. - Abstract: NR5A2 is a nuclear receptor which regulates the expression of genes involved in cholesterol metabolism, pluripotency maintenance and cell differentiation. It has been recently shown that DLPC, a NR5A2 ligand, prevents liver steatosis and improves insulin sensitivity in mouse models of insulin resistance, an effect that has been associated with changes in glucose and fatty acids metabolism in liver. Because skeletal muscle is a major tissue in clearing glucose from blood, we studied the effect of the activation of NR5A2 on muscle metabolism by using cultures of C2C12, a mouse-derived cell line widely used as a model of skeletal muscle. Treatment of C2C12 with DLPC resulted in increased levels of expression of GLUT4 and also of several genes related to glycolysis and glycogen metabolism. These changes were accompanied by an increased glucose uptake. In addition, the activation of NR5A2 produced a reduction in the oxidation of fatty acids, an effect which disappeared in low-glucose conditions. Our results suggest that NR5A2, mostly by enhancing glucose uptake, switches muscle cells into a state of glucose preference. The increased use of glucose by muscle might constitute another mechanism by which NR5A2 improves blood glucose levels and restores insulin sensitivity.

Activation of nuclear receptor NR5A2 increases Glut4 expression and glucose metabolism in muscle cells

International Nuclear Information System (INIS)

Bolado-Carrancio, A.; Riancho, J.A.; Sainz, J.; Rodríguez-Rey, J.C.

2014-01-01

Highlights: • NR5A2 expression in C2C12 is associated with myotube differentiation. • DLPC induces an increase in GLUT4 levels and glucose uptake in C2C12 myotubes. • In high glucose conditions the activation of NR5A2 inhibits fatty acids oxidation. - Abstract: NR5A2 is a nuclear receptor which regulates the expression of genes involved in cholesterol metabolism, pluripotency maintenance and cell differentiation. It has been recently shown that DLPC, a NR5A2 ligand, prevents liver steatosis and improves insulin sensitivity in mouse models of insulin resistance, an effect that has been associated with changes in glucose and fatty acids metabolism in liver. Because skeletal muscle is a major tissue in clearing glucose from blood, we studied the effect of the activation of NR5A2 on muscle metabolism by using cultures of C2C12, a mouse-derived cell line widely used as a model of skeletal muscle. Treatment of C2C12 with DLPC resulted in increased levels of expression of GLUT4 and also of several genes related to glycolysis and glycogen metabolism. These changes were accompanied by an increased glucose uptake. In addition, the activation of NR5A2 produced a reduction in the oxidation of fatty acids, an effect which disappeared in low-glucose conditions. Our results suggest that NR5A2, mostly by enhancing glucose uptake, switches muscle cells into a state of glucose preference. The increased use of glucose by muscle might constitute another mechanism by which NR5A2 improves blood glucose levels and restores insulin sensitivity

A High Fat Diet During Pregnancy and Lactation Induces Cardiac and Renal Abnormalities in GLUT4 +/- Male Mice

Directory of Open Access Journals (Sweden)

Michael Kruse

2017-07-01

Full Text Available Background/Aims: Altered nutrients during the in utero (IU and/or lactation (L period predispose offspring to cardio-renal diseases in adulthood. This study investigates the effect of a high fat diet (HFD fed to female mice during IU/L on gene expression patterns associated with heart and kidney failure and hypertension in male offspring. Methods: Female wild type (WT mice were fed either a HFD or control chow (C prior to mating with males with a genetic heterozygous deletion of GLUT4 (G4+/-, a model of peripheral insulin resistance and hypertension and throughout IU/L. After weaning male offspring were placed on a standard rodent chow until 24 weeks of age. Results: All offspring exposed to a maternal HFD showed increased heart and kidney weight and reduced cardiac insulin responsiveness. G4+/- offspring on a HFD displayed early hypertension associated with increased renal gene expression of renin and the AT1- receptors compared to G4+/- on a C diet. This group showed decreased cardiac expression of key genes involved in fatty acid oxidation compared to WT on a C diet. Conclusions: These results indicate an interaction between a HFD diet and genotype during early life development that can enhance susceptibility to cardio-renal diseases later in life.

In vitro glucose uptake activity of Aegles marmelos and Syzygium cumini by activation of Glut-4, PI3 kinase and PPARgamma in L6 myotubes.

Science.gov (United States)

Anandharajan, R; Jaiganesh, S; Shankernarayanan, N P; Viswakarma, R A; Balakrishnan, A

2006-06-01

The purpose of the present study is to investigate the effect of methanolic extracts of Aegles marmelos and Syzygium cumini on a battery of targets glucose transporter (Glut-4), peroxisome proliferator activator receptor gamma (PPARgamma) and phosphatidylinositol 3' kinase (PI3 kinase) involved in glucose transport. A. marmelos and S. cumini are anti-diabetic medicinal plants being used in Indian traditional medicine. Different solvent extracts extracted sequentially were analysed for glucose uptake activity at each step and methanol extracts were found to be significantly active at 100ng/ml dose comparable with insulin and rosiglitazone. Elevation of Glut-4, PPARgamma and PI3 kinase by A. marmelos and S. cumini in association with glucose transport supported the up-regulation of glucose uptake. The inhibitory effect of cycloheximide on A. marmelos- and S. cumini-mediated glucose uptake suggested that new protein synthesis is required for the elevated glucose transport. Current observation concludes that methanolic extracts of A. marmelos and S. cumini activate glucose transport in a PI3 kinase-dependent fashion.

Evaluating the Efficacy of GLUT Inhibitors Using a Seahorse Extracellular Flux Analyzer.

Science.gov (United States)

Wei, Changyong; Heitmeier, Monique; Hruz, Paul W; Shanmugam, Mala

2018-01-01

Glucose is metabolized through anaerobic glycolysis and aerobic oxidative phosphorylation (OXPHOS). Perturbing glucose uptake and its subsequent metabolism can alter both glycolytic and OXPHOS pathways and consequently lactate and/or oxygen consumption. Production and secretion of lactate, as a consequence of glycolysis, leads to acidification of the extracellular medium. Molecular oxygen is the final electron acceptor in the electron transport chain, facilitating oxidative phosphorylation of ADP to ATP. The alterations in extracellular acidification and/or oxygen consumption can thus be used as indirect readouts of glucose metabolism and assessing the impact of inhibiting glucose transport through specific glucose transporters (GLUTs). The Seahorse bioenergetics analyzer can measure both the oxygen consumption rate (OCR) and extracellular acidification rate (ECAR). The proposed methodology affords a robust, high-throughput method to screen for GLUT inhibition in cells engineered to express specific GLUTs, providing live cell read-outs upon GLUT inhibition.

Long-Term Effect of GPi-DBS in a Patient With Generalized Dystonia Due to GLUT1 Deficiency Syndrome

Directory of Open Access Journals (Sweden)

Idil Hanci

2018-05-01

Full Text Available Treatment outcomes from pallidal deep brain stimulation are highly heterogeneous reflecting the phenotypic and etiologic spectrum of dystonia. Treatment stratification to neurostimulation therapy primarily relies on the phenotypic motor presentation; however, etiology including genetic factors are increasingly recognized as modifiers of treatment outcomes. Here, we describe a 53 year-old female patient with a progressive generalized dystonia since age 25. The patient underwent deep brain stimulation of the globus pallidus internus (GPi-DBS at age 44. Since the clinical phenotype included mobile choreo-dystonic features, we expected favorable therapeutic outcome from GPi-DBS. Although mobile dystonia components were slightly improved in the long-term outcome from GPi-DBS the overall therapeutic response 9 years from implantation was limited when comparing “stimulation off” and “stimulation on” despite of proper electrode localization and sufficient stimulation programming. In order to further understand the reason for this limited motor symptom response, we aimed to clarify the etiology of generalized dystonia in this patient. Genetic testing identified a novel heterozygous pathogenic SLC2A1 mutation as cause of glucose transporter type 1 deficiency syndrome (GLUT1-DS. This case report presents the first outcome of GPi-DBS in a patient with GLUT1-DS, and suggests that genotype relations may increasingly complement phenotype-based therapy stratification of GPi-DBS in dystonia.

High USP6NL levels in breast cancer sustain chronic AKT phosphorylation and GLUT1 stability fueling aerobic glycolysis.

Science.gov (United States)

Avanzato, Daniele; Pupo, Emanuela; Ducano, Nadia; Isella, Claudio; Bertalot, Giovanni; Luise, Chiara; Pece, Salvatore; Bruna, Alejandra; Rueda, Oscar M; Caldas, Carlos; Di Fiore, Pier Paolo; Sapino, Anna; Lanzetti, Letizia

2018-04-24

USP6NL, also named RN-tre, is a GTPase activating protein (GAP) involved in control of endocytosis and signal transduction. Here we report that USP6NL is overexpressed in breast cancer (BC), mainly of the basal-like/integrative cluster 10 subtype. Increased USP6NL levels were accompanied by gene amplification and were associated with worse prognosis in the METABRIC dataset, retaining prognostic value in multivariable analysis. High levels of USP6NL in BC cells delayed endocytosis and degradation of the epidermal growth factor receptor (EGFR), causing chronic AKT activation. In turn, AKT stabilized the glucose transporter GLUT1 at the plasma membrane, increasing aerobic glycolysis. In agreement, elevated USP6NL sensitized BC cells to glucose deprivation, indicating that their glycolytic capacity relies on this protein. Depletion of USP6NL accelerated EGFR/AKT downregulation and GLUT1 degradation, impairing cell proliferation exclusively in BC cells that harbored increased levels of USP6NL. Overall, these findings argue that USP6NL overexpression generates a metabolic rewiring that is essential to foster the glycolytic demand of BC cells and promote their proliferation. Copyright ©2018, American Association for Cancer Research.

The invisible teenager: Comic book materiality and the amateur films of Don Glut

Directory of Open Access Journals (Sweden)

Matt Yockey

2014-06-01

Full Text Available Don Glut, between the ages of 9 and 25, made 41 short amateur films inspired by horror, science fiction, and superhero movies, serials, and comic books. The tactile qualities of comic books as affect-generating objects are instrumental to how Glut confirmed his identity during a time (adolescence in which that identity is particularly unstable. Glut used the popular figure of the teen rebel and his role as a filmmaker in order to negotiate with hegemonic restrictions on his objects of affection, especially comic books.

Gene gun bombardment-mediated expression and translocation of EGFP-tagged GLUT4 in skeletal muscle fibres in vivo

DEFF Research Database (Denmark)

Lauritzen, Hans P M M; Reynet, Christine; Schjerling, Peter

2002-01-01

the enhanced green fluorescent protein (EGFP) labelling technique with physical transfection methods in vivo: intramuscular plasmid injection or gene gun bombardment. During optimisation experiments with plasmid coding for the EGFP reporter alone EGFP-positive muscle fibres were counted after collagenase...... treatment of in vivo transfected flexor digitorum brevis (FDB) muscles. In contrast to gene gun bombardment, intramuscular injection produced EGFP expression in only a few fibres. Regardless of the transfection technique, EGFP expression was higher in muscles from 2-week-old rats than in those from 6-week......Cellular protein trafficking has been studied to date only in vitro or with techniques that are invasive and have a low time resolution. To establish a gentle method for analysis of glucose transporter-4 (GLUT4) trafficking in vivo in fully differentiated rat skeletal muscle fibres we combined...

Gallic acid attenuates high-fat diet fed-streptozotocin-induced insulin resistance via partial agonism of PPARγ in experimental type 2 diabetic rats and enhances glucose uptake through translocation and activation of GLUT4 in PI3K/p-Akt signaling pathway.

Science.gov (United States)

Gandhi, Gopalsamy Rajiv; Jothi, Gnanasekaran; Antony, Poovathumkal James; Balakrishna, Kedike; Paulraj, Michael Gabriel; Ignacimuthu, Savarimuthu; Stalin, Antony; Al-Dhabi, Naif Abdullah

2014-12-15

In this study, the therapeutic efficacy of gallic acid from Cyamopsis tetragonoloba (L.) Taub. (Fabaceae) beans was examined against high-fat diet fed-streptozotocin-induced experimental type 2 diabetic rats. Molecular-dockings were done to determine the putative binding modes of gallic acid into the active sites of key insulin-signaling markers. Gallic acid (20 mg/kg) given to high-fat diet fed-streptozotocin-induced rats lowered body weight gain, fasting blood glucose and plasma insulin in diabetic rats. It further restored the alterations of biochemical parameters to near normal levels in diabetic treated rats along with cytoprotective action on pancreatic β-cell. Histology of liver and adipose tissues supported the biochemical findings. Gallic acid significantly enhanced the level of peroxisome proliferator-activated receptor γ (PPARγ) expression in the adipose tissue of treated rat compared to untreated diabetic rat; it also slightly activated PPARγ expressions in the liver and skeletal muscle. Consequently, it improved insulin-dependent glucose transport in adipose tissue through translocation and activation of glucose transporter protein 4 (GLUT4) in phosphatidylinositol 3-kinase (PI3K)/phosphorylated protein kinase B (p-Akt) dependent pathway. Gallic acid docked with PPARγ; it exhibited promising interactions with the GLUT4, glucose transporter protein 1 (GLUT1), PI3K and p-Akt. These findings provided evidence to show that gallic acid could improve adipose tissue insulin sensitivity, modulate adipogenesis, increase adipose glucose uptake and protect β-cells from impairment. Hence it can be used in the management of obesity-associated type 2 diabetes mellitus. Copyright © 2014 Elsevier B.V. All rights reserved.

Insulin modulates hippocampally-mediated spatial working memory via glucose transporter-4.

Science.gov (United States)

Pearson-Leary, J; Jahagirdar, V; Sage, J; McNay, E C

2018-02-15

The insulin-regulated glucose transporter, GluT4, is a key molecule in peripheral insulin signaling. Although GluT4 is abundantly expressed in neurons of specific brain regions such as the hippocampus, the functional role of neuronal GluT4 is unclear. Here, we used pharmacological inhibition of GluT4-mediated glucose uptake to determine whether GluT4 mediates insulin-mediated glucose uptake in the hippocampus. Consistent with previous reports, we found that glucose utilization increased in the dorsal hippocampus of male rats during spontaneous alternation (SA), a hippocampally-mediated spatial working memory task. We previously showed that insulin signaling within the hippocampus is required for processing this task, and that administration of exogenous insulin enhances performance. At baseline levels of hippocampal insulin, inhibition of GluT4-mediated glucose uptake did not affect SA performance. However, inhibition of an upstream regulator of GluT4, Akt, did impair SA performance. Conversely, when a memory-enhancing dose of insulin was delivered to the hippocampus prior to SA-testing, inhibition of GluT4-mediated glucose transport prevented cognitive enhancement. These data suggest that baseline hippocampal cognitive processing does not require functional hippocampal GluT4, but that cognitive enhancement by supra-baseline insulin does. Consistent with these findings, we found that in neuronal cell culture, insulin increases glucose utilization in a GluT4-dependent manner. Collectively, these data demonstrate a key role for GluT4 in transducing the procognitive effects of elevated hippocampal insulin. Copyright © 2017 Elsevier B.V. All rights reserved.

Loss of sugar detection by GLUT2 affects glucose homeostasis in mice.

Directory of Open Access Journals (Sweden)

Emilie Stolarczyk

Full Text Available BACKGROUND: Mammals must sense the amount of sugar available to them and respond appropriately. For many years attention has focused on intracellular glucose sensing derived from glucose metabolism. Here, we studied the detection of extracellular glucose concentrations in vivo by invalidating the transduction pathway downstream from the transporter-detector GLUT2 and measured the physiological impact of this pathway. METHODOLOGY/PRINCIPAL FINDINGS: We produced mice that ubiquitously express the largest cytoplasmic loop of GLUT2, blocking glucose-mediated gene expression in vitro without affecting glucose metabolism. Impairment of GLUT2-mediated sugar detection transiently protected transgenic mice against starvation and streptozotocin-induced diabetes, suggesting that both low- and high-glucose concentrations were not detected. Transgenic mice favored lipid oxidation, and oral glucose was slowly cleared from blood due to low insulin production, despite massive urinary glucose excretion. Kidney adaptation was characterized by a lower rate of glucose reabsorption, whereas pancreatic adaptation was associated with a larger number of small islets. CONCLUSIONS/SIGNIFICANCE: Molecular invalidation of sugar sensing in GLUT2-loop transgenic mice changed multiple aspects of glucose homeostasis, highlighting by a top-down approach, the role of membrane glucose receptors as potential therapeutic targets.

Long-term In Vitro Treatment of Human Glioblastoma Cells with Temozolomide Increases Resistance In Vivo through Up-regulation of GLUT Transporter and Aldo-Keto Reductase Enzyme AKR1C Expression

Directory of Open Access Journals (Sweden)

Benjamin Le Calvé

2010-09-01

Full Text Available Glioblastoma (GBM is the most frequent malignant glioma. Treatment of GBM patients is multimodal with maximum surgical resection, followed by concurrent radiation and chemotherapy with the alkylating drug temozolomide (TMZ. The present study aims to identify genes implicated in the acquired resistance of two human GBM cells of astrocytic origin, T98G and U373, to TMZ. Resistance to TMZ was induced by culturing these cells in vitro for months with incremental TMZ concentrations up to 1 mM. Only partial resistance to TMZ has been achieved and was demonstrated in vivo in immunocompromised mice bearing orthotopic U373 and T98G xenografts. Our data show that long-term treatment of human astroglioma cells with TMZ induces increased expression of facilitative glucose transporter/solute carrier GLUT/SLC2A family members, mainly GLUT-3, and of the AKR1C family of proteins. The latter proteins are phase 1 drug-metabolizing enzymes involved in the maintenance of steroid homeostasis, prostaglandin metabolism, and metabolic activation of polycyclic aromatic hydrocarbons. GLUT-3 has been previously suggested to exert roles in GBM neovascularization processes, and TMZ was found to exert antiangiogenic effects in experimental gliomas. AKR1C1 was previously shown to be associated with oncogenic potential, with proproliferative effects similar to AKR1C3 in the latter case. Both AKR1C1 and AKR1C2 proteins are involved in cancer pro-proliferative cell chemoresistance. Selective targeting of GLUT-3 in GBM and/or AKR1C proteins (by means of jasmonates, for example could thus delay the acquisition of resistance to TMZ of astroglioma cells in the context of prolonged treatment with this drug.

Affinity between TBC1D4 (AS160 phosphotyrosine-binding domain and insulin-regulated aminopeptidase cytoplasmic domain measured by isothermal titration calorimetry

Directory of Open Access Journals (Sweden)

SangYoun Park*, Keon Young Kim, Sunmin Kim & Young Seok Yu

2012-06-01

Full Text Available Uptake of circulating glucose into the cells happens via the insulin-mediated signalling pathway, which translocates the glucosetransporter 4 (GLUT4 vesicles from the intracellular compartmentto the plasma membrane. RabㆍGTPases are involvedin this vesicle trafficking, where RabㆍGTPase-activatingproteins (RabGAP enhance the GTP to GDP hydrolysis.TBC1D4 (AS160 and TBC1D1 are functional RabGAPs in theadipocytes and the skeletonal myocytes, respectively. Theseproteins contain two phosphotyrosine-binding domains (PTBsat the amino-terminus of the catalytic RabGAP domain. Thesecond PTB has been shown to interact with the cytoplasmicregion of the insulin-regulated aminopeptidase (IRAP of theGLUT4 vesicle. In this study, we quantitatively measured the∼μM affinity (KD between TBC1D4 PTB and IRAP using isothermaltitration calorimetry, and further showed that IRAP residues1-49 are the major region mediating this interaction. Wealso demonstrated that the IRAP residues 1-15 are necessarybut not sufficient for the PTB interaction.

Seizure control and acceptance of the ketogenic diet in GLUT1 deficiency syndrome: a 2- to 5-year follow-up of 15 children enrolled prospectively.

NARCIS (Netherlands)

Klepper, J.; Scheffer, H.; Leiendecker, B.; Gertsen, E.; Binder, S.; Leferink, M.; Hertzberg, C.; Nake, A.; Voit, T.; Willemsen, M.A.A.P.

2005-01-01

BACKGROUND: GLUT1 deficiency syndrome is caused by impaired glucose transport into the brain resulting in an epileptic encephalopathy, developmental delay, and a complex motor disorder. A ketogenic diet provides an alternative fuel to the brain and effectively restores brain energy metabolism.

Diabetes-Resistant NOR Mice Are More Severely Affected by Streptozotocin Compared to the Diabetes-Prone NOD Mice: Correlations with Liver and Kidney GLUT2 Expressions

Directory of Open Access Journals (Sweden)

S. Kahraman

2015-01-01

Full Text Available Nonobese Diabetic (NOD mice are susceptible strains for Type 1 diabetes development, and Nonobese Diabetes-Resistant (NOR mice are defined as suitable controls for NOD mice in non-MHC-related research. Diabetes is often accelerated in NOD mice via Streptozotocin (STZ. STZ is taken inside cells via GLUT2 transmembrane carrier proteins, the major glucose transporter isoforms in pancreatic beta cells, liver, kidneys, and the small intestine. We observed severe adverse effects in NOR mice treated with STZ compared to NOD mice that were made diabetic with a similar dose. We suggested that the underlying mechanism could be differential GLUT2 expressions in pancreatic beta cells, yet immunofluorescent and immunohistochemical studies revealed similar GLUT2 expression levels. We also detected GLUT2 expression profiles in NOD and NOR hepatic and renal tissues by western blot analysis and observed considerably higher GLUT2 expression levels in liver and kidney tissues of NOR mice. Although beta cell GLUT2 expression levels are frequently evaluated as a marker predicting STZ sensitivity in animal models, we report here very different diabetic responses to STZ in two different animal strains, in spite of similar initial GLUT2 expressions in beta cells. Furthermore, use of NOR mice in STZ-mediated experimental diabetes settings should be considered accordingly.

Crescimento de mudas de orégano submetidas a doses e frequências de aplicação de Ácido L-glutâmico em sistema orgânico

Directory of Open Access Journals (Sweden)

M.B. Bettoni

2014-03-01

Full Text Available O presente trabalho teve por objetivo identificar o efeito de diferentes doses e frequências de aplicação do biofertilizante aminoácido Ácido L-glutâmico em mudas de orégano produzidas em sistema orgânico, quantificando seu crescimento. Os tratamentos compostos por 2 doses (0,4 e 0,8 mL L-1 de Ácido L-glutâmico a 30%, e testemunha com água, foram aplicados via foliar em intervalos regulares de 7 e 14 dias, por 28 dias (fatorial 3 x 2, com 4 e 2 aplicações, respectivamente, em delineamento inteiramente casualizado com 4 repetições. Aos 62 dias após a semeadura foi realizada a coleta de 8 plantas centrais por repetição para avaliação de características biométricas da parte aérea e das raízes. O experimento demonstrou que o biofertilizante aminoácido ácido L-glutâmico influenciou as características avaliadas. A dose de 0,8 mL L-1, aplicada com intervalo de 14 dias, promoveu maior crescimento das mudas de orégano.

Association of a common nonsynonymous variant in GLUT9 with serum uric acid levels in old order amish.

Science.gov (United States)

McArdle, Patrick F; Parsa, Afshin; Chang, Yen-Pei C; Weir, Matthew R; O'Connell, Jeffery R; Mitchell, Braxton D; Shuldiner, Alan R

2008-09-01

Uric acid is the primary end product of purine metabolism. Increased serum uric acid levels have been associated with gouty arthritis as well as with a variety of cardiovascular-related phenotypes. This study was undertaken to investigate associations between uric acid levels and single-nucleotide polymorphisms (SNPs). A 500,000-SNP genome-wide association study of serum uric acid levels was performed in a cohort of Old Order Amish from Lancaster County, Pennsylvania. The scan confirmed a previously identified region on chromosome 4 to be strongly associated with uric acid levels (P = 4.2 x 10(-11) for rs10489070). Followup genotyping revealed that a nonsynonymous coding SNP (Val253Ile; rs16890979) in GLUT9 was most strongly associated with uric acid levels, with each copy of the minor allele associated with a decrease of 0.47 mg/dl in the uric acid level (95% confidence interval 0.31-0.63 [P = 1.43 x 10(-11)]). The effect of this variant tended to be stronger in women than in men (P = 0.16 for sex-genotype interaction). The genotype effect was not modified by the inclusion of several cardiovascular risk factors, suggesting that GLUT9 is directly related to uric acid homeostasis. The SNP identified in the genome-wide scan in the Amish population (rs10489070) was also significantly associated with gout in the Framingham Heart Study (P = 0.004). Our findings indicate that GLUT9, which is expressed in the kidney, may be a novel regulator of uric acid elimination and that a common nonsynonymous variant in this gene contributes to abnormalities in uric acid homeostasis and gout.

AICAR administration affects glucose metabolism by upregulating the novel glucose transporter, GLUT8, in equine skeletal muscle.

Science.gov (United States)

de Laat, M A; Robinson, M A; Gruntmeir, K J; Liu, Y; Soma, L R; Lacombe, V A

2015-09-01

Equine metabolic syndrome is characterized by obesity and insulin resistance (IR). Currently, there is no effective pharmacological treatment for this insidious disease. Glucose uptake is mediated by a family of glucose transporters (GLUT), and is regulated by insulin-dependent and -independent pathways, including 5-AMP-activated protein kinase (AMPK). Importantly, the activation of AMPK, by 5-aminoimidazole-4-carboxamide-1-D-ribofuranoside (AICAR) stimulates glucose uptake in both healthy and diabetic humans. However, whether AICAR promotes glucose uptake in horses has not been established. It is hypothesized that AICAR administration would enhance glucose transport in equine skeletal muscle through AMPK activation. In this study, the effect of an intravenous AICAR infusion on blood glucose and insulin concentrations, as well as on GLUT expression and AMPK activation in equine skeletal muscle (quantified by Western blotting) was examined. Upon administration, plasma AICAR rapidly reached peak concentration. Treatment with AICAR resulted in a decrease (P change in lactate concentration. The ratio of phosphorylated to total AMPK was increased (P managing IR requires investigation. Copyright © 2015 Elsevier Ltd. All rights reserved.

Alkaline pH activates the transport activity of GLUT1 in L929 fibroblast cells.

Science.gov (United States)

Gunnink, Stephen M; Kerk, Samuel A; Kuiper, Benjamin D; Alabi, Ola D; Kuipers, David P; Praamsma, Riemer C; Wrobel, Kathryn E; Louters, Larry L

2014-04-01

The widely expressed mammalian glucose transporter, GLUT1, can be acutely activated in L929 fibroblast cells by a variety of conditions, including glucose deprivation, or treatment with various respiration inhibitors. Known thiol reactive compounds including phenylarsine oxide and nitroxyl are the fastest acting stimulators of glucose uptake, implicating cysteine biochemistry as critical to the acute activation of GLUT1. In this study, we report that in L929 cells glucose uptake increases 6-fold as the pH of the uptake solution is increased from 6 to 9 with the half-maximal activation at pH 7.5; consistent with the pKa of cysteine residues. This pH effect is essentially blocked by the pretreatment of the cells with either iodoacetamide or cinnamaldehyde, compounds that form covalent adducts with reduced cysteine residues. In addition, the activation by alkaline pH is not additive at pH 8 with known thiol reactive activators such as phenylarsine oxide or hydroxylamine. Kinetic analysis in L929 cells at pH 7 and 8 indicate that alkaline conditions both increases the Vmax and decreases the Km of transport. This is consistent with the observation that pH activation is additive to methylene blue, which activates uptake by increasing the Vmax, as well as to berberine, which activates uptake by decreasing the Km. This suggests that cysteine biochemistry is utilized in both methylene blue and berberine activation of glucose uptake. In contrast a pH increase from 7 to 8 in HCLE cells does not further activate glucose uptake. HCLE cells have a 25-fold higher basal glucose uptake rate than L929 cells and the lack of a pH effect suggests that the cysteine biochemistry has already occurred in HCLE cells. The data are consistent with pH having a complex mechanism of action, but one likely mediated by cysteine biochemistry. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

Nutritional status induces divergent variations of GLUT4 protein content, but not lipoprotein lipase activity, between adipose tissues and muscles in adult cattle.

Science.gov (United States)

Bonnet, Muriel; Faulconnier, Yannick; Hocquette, Jean-François; Bocquier, François; Leroux, Christine; Martin, Patrice; Chilliard, Yves

2004-10-01

Metabolic adaptations to variations in food supply are incompletely understood in ruminant animal adipose tissue (AT) and muscle. To explore this, we studied lipid metabolism and glucose transport potential in one internal and one external AT, as well as in one oxidative and one glycolytic muscle from control, 7 d underfed and 21 d refed adult cows. Refeeding increased (+79 to +307 %) the activities of enzymes involved in de novo lipogenesis (fatty acid synthase, malic enzyme, glucose-6-phosphate dehydrogenase) in perirenal and subcutaneous AT; underfeeding did not modify these variables. Underfeeding decreased the activities of lipoprotein lipase (LPL) in perirenal AT (-70 %) and cardiac muscle (-67 %), but did not modify the activities in subcutaneous AT and longissimus thoracis. Refeeding increased LPL activities in all tissues (+40 to +553 %) to levels comparable with (cardiac muscle) or greater than (AT, longissimus thoracis) those observed in control cows. Such variations in perirenal and cardiac muscle LPL activities did not result from variations in LPL mRNA levels, but suggest a post-transcriptional regulation of LPL in these nutritional conditions. Underfeeding did not modify GLUT4 contents in perirenal AT and muscles, while refeeding increased it only in perirenal AT (+250 %). Our present results contrast with previous results in rats, where LPL is regulated in opposite directions in AT and muscles, and GLUT4 is generally increased by fasting and decreased by refeeding in skeletal muscles. The present results highlight the bovine specificity of the response, which probably arises in part from peculiarities of ruminant animals for nutrient digestion and absorption.

Insulin-sparing and fungible effects of E4orf1 combined with an adipocyte-targeting sequence in mouse models of type 1 and type 2 diabetes.

Science.gov (United States)

Yoon, I-S; Park, S; Kim, R-H; Ko, H L; Nam, J-H

2017-10-01

Obesity impairs glycemic control and causes insulin resistance and type 2 diabetes. Adenovirus 36 (Ad36) infection can increase the uptake of excess glucose from blood into adipocytes by increasing GLUT4 translocation through the Ras-Akt signaling pathway, which bypasses PI3K-Akt-mediated insulin receptor signaling. E4orf1, a viral gene expressed early during Ad36 infection, is responsible for this insulin-sparing effect and may be an alternative target for improving insulin resistance. To deliver the gene to adipocytes only, we connected the adipocyte-targeting sequence (ATS) to the 5' end of E4orf1 (ATS-E4orf1). In vitro transfection of ATS-E4orf1 into preadipocytes activated factors for GLUT4 translocation and adipogenesis to the same extent as did Hemagglutinin (HA)-E4orf1 transfection as positive reference. Moreover, the Transwell migration assay also showed that ATS-E4orf1 secreted by liver cells activated Akt in preadipocytes. We used a hydrodynamic gene delivery technique to deliver ATS-E4orf1 into high-fat diet-fed and streptozotocin-injected mice (disease models of type 2 and type 1 diabetes, respectively). ATS-E4orf1 improved the ability to eliminate excess glucose from the blood and ameliorated liver function in both disease models. These findings suggest that ATS-E4orf1 has insulin-sparing and fungible effects in type 2 and 1 diabetes independent of the presence of insulin.

GLUT2 in pancreatic islets: crucial target molecule in diabetes induced with multiple low doses of streptozotocin in mice.

Science.gov (United States)

Wang, Z; Gleichmann, H

1998-01-01

In mice, diabetes can be induced by multiple low doses of streptozotocin (MLD-STZ), i.e., 40 mg/kg body wt on each of 5 consecutive days. In this model, diabetes develops only when STZ induces both beta-cell toxicity and T-cell-dependent immune reactions. The target molecule(s) of MLD-STZ-induced beta-cell toxicity are not known, however. In this study, we report that GLUT2 is a target molecule for MLD-STZ toxicity. Ex vivo, a gradual decrement of both GLUT2 protein and mRNA expression was found in pancreatic islets isolated from MLD-STZ-treated C57BL/6 male mice, whereas mRNA expression of beta-actin, glucokinase, and proinsulin remained unaffected. Significant reduction of both GLUT2 protein and mRNA expression was first noted 1 day after the third STZ injection, clearly preceding the onset of hyperglycemia. The extent of reduction increased with the number of STZ injections administered and increased over time, after the last, i.e., fifth, STZ injection. The STZ-induced reduction of GLUT2 protein and mRNA was not due to an essential loss of beta-cells, because ex vivo, not only the total RNA yield and protein content in isolated islets, but also proinsulin mRNA expression, failed to differ significantly in the differently treated groups. Furthermore, islets isolated from MLD-STZ-treated donors responded to the nonglucose secretagogue arginine in a pattern similar to that of solvent-treated donors. Interestingly, the MLD-STZ-induced reduction of both GLUT2 protein and mRNA was prevented by preinjecting mice with 5-thio-D-glucose before each STZ injection. Apparently, GLUT2 is a crucial target molecule of MLD-STZ toxicity, and this toxicity seems to precede the immune reactions against beta-cells.

The RabGAP TBC1D1 plays a central role in exercise-regulated glucose metabolism in skeletal muscle

DEFF Research Database (Denmark)

Stöckli, Jacqueline; Meoli, Christopher C; Hoffman, Nolan J

2015-01-01

Insulin and exercise stimulate glucose uptake into skeletal muscle via different pathways. Both stimuli converge on the translocation of the glucose transporter GLUT4 from intracellular vesicles to the cell surface. Two Rab guanosine triphosphatases-activating proteins (GAPs) have been implicated...... weight, insulin action, and exercise. TBC1D1(-/-) mice showed normal glucose and insulin tolerance, with no difference in body weight compared with wild-type littermates. GLUT4 protein levels were reduced by ∼40% in white TBC1D1(-/-) muscle, and TBC1D1(-/-) mice showed impaired exercise endurance...... together with impaired exercise-mediated 2-deoxyglucose uptake into white but not red muscles. These findings indicate that the RabGAP TBC1D1 plays a key role in regulating GLUT4 protein levels and in exercise-mediated glucose uptake in nonoxidative muscle fibers....

Glucose stimulates neurotensin secretion from the rat small intestine by mechanisms involving SGLT1 and GLUT2 leading to cell depolarization and calcium influx

DEFF Research Database (Denmark)

Kuhre, Rune Ehrenreich; Bechmann, Louise Ellegaard; Hartmann, Bolette

2015-01-01

of secretion. Luminal glucose (20% wt/vol) stimulated secretion but vascular glucose (5, 10, or 15 mmol/l) was without effect. The underlying mechanisms depend on membrane depolarization and calcium influx, since the voltage-gated calcium channel inhibitor nifedipine and the KATP channel opener diazoxide......, suggesting that glucose stimulates secretion by initial uptake by this transporter. However, secretion was also sensitive to GLUT2 inhibition (by phloretin) and blockage of oxidative phosphorylation (2-4-dinitrophenol). Direct KATP channel closure by sulfonylureas stimulated secretion. Therefore, glucose...

Genetic analysis of the GLUT10 glucose transporter (SLC2A10 polymorphisms in Caucasian American type 2 diabetes

Directory of Open Access Journals (Sweden)

Mychaleckyj Josyf C

2005-12-01

Full Text Available Abstract Background GLUT10 (gene symbol SLC2A10 is a facilitative glucose transporter within the type 2 diabetes (T2DM-linked region on chromosome 20q12-13.1. Therefore, we evaluated GLUT10 as a positional candidate gene for T2DM in Caucasian Americans. Methods Twenty SNPs including 4 coding, 10 intronic and 6 5' and 3' to the coding sequence were genotyped across a 100 kb region containing the SLC2A10 gene in DNAs from 300 T2DM cases and 310 controls using the Sequenom MassArray Genotyping System. Allelic association was evaluated, and linkage disequilibrium (LD and haplotype structure of SLC2A10 were also determined to assess whether any specific haplotypes were associated with T2DM. Results Of these variants, fifteen had heterozygosities greater than 0.80 and were analyzed further for association with T2DM. No evidence of significant association was observed for any variant with T2DM (all P ≥ 0.05, including Ala206Thr (rs2235491 which was previously reported to be associated with fasting insulin. Linkage disequilibrium analysis suggests that the SLC2A10 gene is contained in a single haplotype block of 14 kb. Haplotype association analysis with T2DM did not reveal any significant differences between haplotype frequencies in T2DM cases and controls. Conclusion From our findings, we can conclude that sequence variants in or near GLUT10 are unlikely to contribute significantly to T2DM in Caucasian Americans.

Brain Transport Profiles of Ginsenoside Rb1 by Glucose Transporter 1: In Vitro and in Vivo

Directory of Open Access Journals (Sweden)

Yu-Zhu Wang

2018-04-01

Full Text Available Ginsenoside Rb1 (Rb1 has been demonstrated its protection for central nervous system and is apparently highly distributed to the brain. The objective of this study was to characterize Rb1 transport at the blood–brain barrier (BBB using primary cultured rat brain microvascular endothelial cells (rBMEC, an in vitro BBB model. The initial uptake velocity of Rb1 in rBMEC was temperature- and concentration-dependent, and was significantly reduced by phloretin, an inhibitor of GLUT1 transporter, but was independent of metabolic inhibitor. Furthermore, the transport of Rb1 into rBMEC was significantly diminished in the presence of natural substrate α-D-glucose, suggesting a facilitated transport of Rb1 via GLUT1 transporter. The impact of GLUT1 on the distribution of Rb1 between brain and plasma was studied experimentally in rats. Administration of phloretin (5 mg/kg, i.v. to normal rats for consecutive 1 week before Rb1 (10 mg/kg, i.v. at 0.5, 2, and 6 h did not alter Rb1 concentrations in plasma, but resulted in significant decreased brain concentrations of Rb1 compared to in the phloretin-untreated normal rats (489.6 ± 58.3 versus 105.1 ± 15.1 ng/g, 193.8 ± 11.1 versus 84.8 ± 4.1 ng/g, and 114.2 ± 24.0 versus 39.9 ± 4.9 ng/g, respectively. The expression of GLUT1 in the phloretin-treated group by western blotting analysis in vitro and in vivo experiments was significantly decreased, indicating that the decreased transport of Rb1 in brain was well related to the down-regulated function and level of GLUT1. Therefore, our in vitro and in vivo results indicate that the transport of Rb1 at the BBB is at least partly mediated by GLUT1 transporter.

Radiopharmacological evaluation of 6-deoxy-6-[{sup 18}F]fluoro-D-fructose as a radiotracer for PET imaging of GLUT5 in breast cancer

Energy Technology Data Exchange (ETDEWEB)

Wuest, Melinda, E-mail: mwuest@ualberta.c [Department of Oncology, University of Alberta - Cross Cancer Institute, Edmonton, AB-T6G 1Z2 (Canada); Trayner, Brendan J. [Department of Physiology, University of Alberta, Edmonton, AB-T6G 1Z2 (Canada); Grant, Tina N. [Department of Physiology, University of Alberta, Edmonton, AB-T6G 1Z2 (Canada); Department of Chemistry, University of Alberta, Edmonton, AB-T6G 1Z2 (Canada); Jans, Hans-Soenke; Mercer, John R.; Murray, David [Department of Oncology, University of Alberta - Cross Cancer Institute, Edmonton, AB-T6G 1Z2 (Canada); West, Frederick G. [Department of Chemistry, University of Alberta, Edmonton, AB-T6G 1Z2 (Canada); McEwan, Alexander J.B.; Wuest, Frank [Department of Oncology, University of Alberta - Cross Cancer Institute, Edmonton, AB-T6G 1Z2 (Canada); Cheeseman, Chris I. [Department of Physiology, University of Alberta, Edmonton, AB-T6G 1Z2 (Canada)

2011-05-15

Introduction: Several clinical studies have shown low or no expression of GLUT1 in breast cancer patients, which may account for the low clinical specificity and sensitivity of 2-deoxy-2-[{sup 18}F]fluoro-D-glucose ([{sup 18}F]FDG) used in positron emission tomography (PET). Therefore, it has been proposed that other tumor characteristics such as the high expression of GLUT2 and GLUT5 in many breast tumors could be used to develop alternative strategies to detect breast cancer. Here we have studied the in vitro and in vivo radiopharmacological profile of 6-deoxy-6-[{sup 18}F]fluoro-D-fructose (6-[{sup 18}F]FDF) as a potential PET radiotracer to image GLUT5 expression in breast cancers. Methods: Uptake of 6-[{sup 18}F]FDF was studied in murine EMT-6 and human MCF-7 breast cancer cells over 60 min and compared to [{sup 18}F]FDG. Biodistribution of 6-[{sup 18}F]FDF was determined in BALB/c mice. Tumor uptake was studied with dynamic small animal PET in EMT-6 tumor-bearing BALB/c mice and human xenograft MCF-7 tumor-bearing NIH-III mice in comparison to [{sup 18}F]FDG. 6-[{sup 18}F]FDF metabolism was investigated in mouse blood and urine. Results: 6-[{sup 18}F]FDF is taken up by EMT-6 and MCF-7 breast tumor cells independent of extracellular glucose levels but dependent on the extracellular concentration of fructose. After 60 min, 30{+-}4% (n=9) and 12{+-}1% (n=7) ID/mg protein 6-[{sup 18}F]FDF was found in EMT-6 and MCF-7 cells, respectively. 6-deoxy-6-fluoro-D-fructose had a 10-fold higher potency than fructose to inhibit 6-[{sup 18}F]FDF uptake into EMT-6 cells. Biodistribution in normal mice revealed radioactivity uptake in bone and brain. Radioactivity was accumulated in EMT-6 tumors reaching 3.65{+-}0.30% ID/g (n=3) at 5 min post injection and decreasing to 1.75{+-}0.03% ID/g (n=3) at 120 min post injection. Dynamic small animal PET showed significantly lower radioactivity uptake after 15 min post injection in MCF-7 tumors [standard uptake value (SUV)=0

Glut2-dependent glucose-sensing controls thermoregulation by enhancing the leptin sensitivity of NPY and POMC neurons.

Science.gov (United States)

Mounien, Lourdes; Marty, Nell; Tarussio, David; Metref, Salima; Genoux, David; Preitner, Frédéric; Foretz, Marc; Thorens, Bernard

2010-06-01

The physiological contribution of glucose in thermoregulation is not completely established nor whether this control may involve a regulation of the melanocortin pathway. Here, we assessed thermoregulation and leptin sensitivity of hypothalamic arcuate neurons in mice with inactivation of glucose transporter type 2 (Glut2)-dependent glucose sensing. Mice with inactivation of Glut2-dependent glucose sensors are cold intolerant and show increased susceptibility to food deprivation-induced torpor and abnormal hypothermic response to intracerebroventricular administration of 2-deoxy-d-glucose compared to control mice. This is associated with a defect in regulated expression of brown adipose tissue uncoupling protein I and iodothyronine deiodinase II and with a decreased leptin sensitivity of neuropeptide Y (NPY) and proopiomelanocortin (POMC) neurons, as observed during the unfed-to-refed transition or following i.p. leptin injection. Sites of central Glut-2 expression were identified by a genetic tagging approach and revealed that glucose-sensitive neurons were present in the lateral hypothalamus, the dorsal vagal complex, and the basal medulla but not in the arcuate nucleus. NPY and POMC neurons were, however, connected to nerve terminals from Glut2-expressing neurons. Thus, our data suggest that glucose controls thermoregulation and the leptin sensitivity of NPY and POMC neurons through activation of Glut2-dependent glucose-sensing neurons located outside of the arcuate nucleus.

Short-term impact of a classical ketogenic diet on gut microbiota in GLUT1 Deficiency Syndrome: A 3-month prospective observational study.

Science.gov (United States)

Tagliabue, Anna; Ferraris, Cinzia; Uggeri, Francesca; Trentani, Claudia; Bertoli, Simona; de Giorgis, Valentina; Veggiotti, Pierangelo; Elli, Marina

2017-02-01

The classical ketogenic diet (KD) is a high-fat, very low-carbohydrate normocaloric diet used for drug-resistant epilepsy and Glucose Transporter 1 Deficiency Syndrome (GLUT1 DS). In animal models, high fat diet induces large alterations in microbiota producing deleterious effects on gut health. We carried out a pilot study on patients treated with KD comparing their microbiota composition before and after three months on the diet. Six patients affected by GLUT1 DS were asked to collect fecal samples before and after three months on the diet. RT - PCR analysis was performed in order to quantify Firmicutes, Bacteroidetes, Bifidobacterium spp., Lactobacillus spp., Clostridium perfringens, Enterobacteriaceae, Clostridium cluster XIV, Desulfovibrio spp. and Faecalibacterium prausnitzii. Compared with baseline, there were no statistically significant differences at 3 months in Firmicutes and Bacteroidetes. However fecal microbial profiles revealed a statistically significant increase in Desulfovibrio spp. (p = 0.025), a bacterial group supposed to be involved in the exacerbation of the inflammatory condition of the gut mucosa associated to the consumption of fats of animal origin. A future prospective study on the changes in gut microbiota of all children with epilepsy started on a KD is warranted. In patients with dysbiosis demonstrated by fecal samples, it my be reasonable to consider an empiric trial of pre or probiotics to potentially restore the «ecological balance» of intestinal microbiota. Copyright © 2016 European Society for Clinical Nutrition and Metabolism. Published by Elsevier Ltd. All rights reserved.

Antioxidant and glucose metabolizing potential of edible insect, Brachytrupes orientalis via modulating Nrf2/AMPK/GLUT4 signaling pathway.

Science.gov (United States)

Dutta, Prachurjya; Dey, Tapan; Dihingia, Anjum; Manna, Prasenjit; Kalita, Jatin

2017-11-01

Brachytrupes orientalis (Gryllidae) is a common edible insect species eaten by the different tribes of North East India. This study investigated the potentiality of Brachytrupes orientalis extracts in different solvent hydro-alcoholic (AEBO), hexane (HEBO) and ethyl acetate (EEBO) on glucose utilization and cell viability in high glucose (HG) treated myotubes. It has been observed that AEBO supplementation significantly increased the glucose utilization against HG exposure; however, treatment HEBO and EEBO have no significant effect. AEBO also increased the intercellular glucose-6-phosphate level and the protein expression of both phospho-AMPK and GLUT4 in HG treated myotubes in a dose dependent manner. Furthermore, supplementation with AEBO decreased the intercellular ROS production, lipid peroxidation, and up-regulated the protein expression of Nrf2 and GST. Chromatography and Spectroscopic analyses of AEBO also suggest that Ursolic acid may be one of the bioactive principles with rich potassium, sodium, calcium and magnesium content. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Sodium-glucose co-transporter (SGLT) and glucose transporter (GLUT) expression in the kidney of type 2 diabetic subjects.

Science.gov (United States)

Norton, Luke; Shannon, Christopher E; Fourcaudot, Marcel; Hu, Cheng; Wang, Niansong; Ren, Wei; Song, Jun; Abdul-Ghani, Muhammad; DeFronzo, Ralph A; Ren, Jimmy; Jia, Weiping

2017-09-01

The sodium-glucose co-transporters (SGLTs) are responsible for the tubular reabsorption of filtered glucose from the kidney into the bloodstream. The inhibition of SGLT2-mediated glucose reabsorption is a novel and highly effective strategy to alleviate hyperglycaemia in patients with type 2 diabetes mellitus (T2DM). However, the effectiveness of SGLT2 inhibitor therapy is diminished due, in part, to a compensatory increase in the maximum reabsorptive capacity (Tm) for glucose in patients with T2DM. We hypothesized that this increase in Tm could be explained by an increase in the tubular expression of SGLT and glucose transporters (GLUT) in these patients. To examine this, we obtained human kidney biopsy specimens from patients with or without T2DM and examined the mRNA expression of SGLTs and GLUTs. The expression of SGLT1 is markedly increased in the kidney of patients with T2DM, and SGLT1 mRNA is highly and significantly correlated with fasting and postprandial plasma glucose and HbA1c. In contrast, our data demonstrate that the levels of SGLT2 and GLUT2 mRNA are downregulated in diabetic patients, but not to a statistically significant level. These important findings are clinically significant and may have implications for the treatment of T2DM using strategies that target SGLT transporters in the kidney. © 2017 John Wiley & Sons Ltd.

Adenovirus Protein E4-ORF1 activation of PI3 kinase reveals differential regulation of downstream effector pathways in adipocytes

OpenAIRE

Chaudhary, Natasha; Gonzalez, Eva; Chang, Sung-Hee; Geng, Fuqiang; Rafii, Shahin; Altorki, Nasser K.; McGraw, Timothy E.

2016-01-01

Insulin activation of phosphatidylinositol 3-kinase (PI3K) regulates metabolism, including the translocation of the Glut4 glucose transporter to the plasma membrane and inactivation of the FoxO1 transcription factor. Adenoviral protein E4-ORF1 stimulates cellular glucose metabolism by mimicking growth-factor activation of PI3K. We have used E4-ORF1 as a tool to dissect PI3K-mediated signaling in adipocytes. E4-ORF1 activation of PI3K in adipocytes recapitulates insulin regulation of FoxO1 but...

Fructose-induced increases in expression of intestinal fructolytic and gluconeogenic genes are regulated by GLUT5 and KHK

Science.gov (United States)

Patel, Chirag; Douard, Veronique; Yu, Shiyan; Tharabenjasin, Phuntila; Gao, Nan

2015-01-01

Marked increases in fructose consumption have been tightly linked to metabolic diseases. One-third of ingested fructose is metabolized in the small intestine, but the underlying mechanisms regulating expression of fructose-metabolizing enzymes are not known. We used genetic mouse models to test the hypothesis that fructose absorption via glucose transporter protein, member 5 (GLUT5), metabolism via ketohexokinase (KHK), as well as GLUT5 trafficking to the apical membrane via the Ras-related protein in brain 11a (Rab11a)-dependent endosomes are required for the regulation of intestinal fructolytic and gluconeogenic enzymes. Fructose feeding increased the intestinal mRNA and protein expression of these enzymes in the small intestine of adult wild-type (WT) mice compared with those gavage fed with lysine or glucose. Fructose did not increase expression of these enzymes in the GLUT5 knockout (KO) mice. Blocking intracellular fructose metabolism by KHK ablation also prevented fructose-induced upregulation. Glycolytic hexokinase I expression was similar between WT and GLUT5- or KHK-KO mice and did not vary with feeding solution. Gavage feeding with the fructose-specific metabolite glyceraldehyde did not increase enzyme expression, suggesting that signaling occurs before the hydrolysis of fructose to three-carbon compounds. Impeding GLUT5 trafficking to the apical membrane using intestinal epithelial cell-specific Rab11a-KO mice impaired fructose-induced upregulation. KHK expression was uniformly distributed along the villus but was localized mainly in the basal region of the cytosol of enterocytes. The feedforward upregulation of fructolytic and gluconeogenic enzymes specifically requires GLUT5 and KHK and may proactively enhance the intestine's ability to process anticipated increases in dietary fructose concentrations. PMID:26084694

2-(4-Methoxyphenyl)ethyl-2-acetamido-2-deoxy-β-D-pyranoside confers neuroprotection in cell and animal models of ischemic stroke through calpain1/PKA/CREB-mediated induction of neuronal glucose transporter 3

Energy Technology Data Exchange (ETDEWEB)

Yu, Shu; Cheng, Qiong; Li, Lu; Liu, Mei; Yang, Yumin; Ding, Fei, E-mail: dingfei@ntu.edu.cn

2014-06-15

Salidroside is proven to be a neuroprotective agent of natural origin, and its analog, 2-(4-Methoxyphenyl)ethyl-2-acetamido-2-deoxy-β-D-pyranoside (named SalA-4 g), has been synthesized in our lab. In this study, we showed that SalA-4 g promoted neuronal survival and inhibited neuronal apoptosis in primary hippocampal neurons exposed to oxygen and glucose deprivation (OGD) and in rats subjected to ischemia by transient middle cerebral artery occlusion (MCAO), respectively, and that SalA-4 g was more neuroprotective than salidroside. We further found that SalA-4 g elevated glucose uptake in OGD-injured primary hippocampal neurons and increased the expression and recruitment of glucose transporter 3 (GLUT3) in ischemic brain. Signaling analysis revealed that SalA-4 g triggered the phosphorylation of CREB, and increased the expression of PKA RII in primary hippocampal neurons exposed to OGD injury, while inhibition of PKA/CREB by H-89 alleviated the elevation in glucose uptake and GLUT3 expression, and blocked the protective effects of SalA-4 g. Moreover, SalA-4 g was noted to inhibit intracellular Ca{sup 2+} influx and calpain1 activation in OGD-injured primary hippocampal neurons. Our results suggest that SalA-4 g neuroprotection might be mediated by increased glucose uptake and elevated GLUT3 expression through calpain1/PKA/CREB pathway. - Highlights: • A salidroside (Sal) analog (SalA-4 g) is prepared to be more neuroprotective than Sal. • SalA-4 g protected hippocampal neurons from oxygen and glucose deprivation insult. • SalA-4 g reduced ischemic injury after transient middle cerebral artery occlusion in rats. • Neuroprotection of SalA-4 g was mediated by GLUT3 level via calpain/PKA/CREB pathway.

2-(4-Methoxyphenyl)ethyl-2-acetamido-2-deoxy-β-D-pyranoside confers neuroprotection in cell and animal models of ischemic stroke through calpain1/PKA/CREB-mediated induction of neuronal glucose transporter 3

International Nuclear Information System (INIS)

Yu, Shu; Cheng, Qiong; Li, Lu; Liu, Mei; Yang, Yumin; Ding, Fei

2014-01-01

Salidroside is proven to be a neuroprotective agent of natural origin, and its analog, 2-(4-Methoxyphenyl)ethyl-2-acetamido-2-deoxy-β-D-pyranoside (named SalA-4 g), has been synthesized in our lab. In this study, we showed that SalA-4 g promoted neuronal survival and inhibited neuronal apoptosis in primary hippocampal neurons exposed to oxygen and glucose deprivation (OGD) and in rats subjected to ischemia by transient middle cerebral artery occlusion (MCAO), respectively, and that SalA-4 g was more neuroprotective than salidroside. We further found that SalA-4 g elevated glucose uptake in OGD-injured primary hippocampal neurons and increased the expression and recruitment of glucose transporter 3 (GLUT3) in ischemic brain. Signaling analysis revealed that SalA-4 g triggered the phosphorylation of CREB, and increased the expression of PKA RII in primary hippocampal neurons exposed to OGD injury, while inhibition of PKA/CREB by H-89 alleviated the elevation in glucose uptake and GLUT3 expression, and blocked the protective effects of SalA-4 g. Moreover, SalA-4 g was noted to inhibit intracellular Ca 2+ influx and calpain1 activation in OGD-injured primary hippocampal neurons. Our results suggest that SalA-4 g neuroprotection might be mediated by increased glucose uptake and elevated GLUT3 expression through calpain1/PKA/CREB pathway. - Highlights: • A salidroside (Sal) analog (SalA-4 g) is prepared to be more neuroprotective than Sal. • SalA-4 g protected hippocampal neurons from oxygen and glucose deprivation insult. • SalA-4 g reduced ischemic injury after transient middle cerebral artery occlusion in rats. • Neuroprotection of SalA-4 g was mediated by GLUT3 level via calpain/PKA/CREB pathway

Immunohistochemical Evaluation of Glucose Transporter Type 1 in Epithelial Dysplasia and Oral Squamous Cell Carcinoma.

Science.gov (United States)

Pereira, Karuza Maria Alves; Feitosa, Sthefane Gomes; Lima, Ana Thayssa Tomaz; Luna, Ealber Carvalho Macedo; Cavalcante, Roberta Barroso; de Lima, Kenio Costa; Chaves, Filipe Nobre; Costa, Fábio Wildson Gurgel

2016-01-01

Oral squamous cell carcinoma (OSCC) is the most common malignancy of the oral cavity and some of these have been documented in association or preceded by oral epithelial dysplasia (OED). Aggressive cancers with fast growth have demonstrated overexpression of some glucose transporters (GLUTs). Thus, the aim of this study was to analyze the immunohistochemical expression of the glucose transporter, GLUT-1, in OEDs and OSCCs, seeking to better elucidate the biological behavior of neoplasias. Fifteen cases were selected this research of both lesions. Five areas were analyzed from each case by counting the percentage of positive cells at 400x magnification. Immunoreactivity of GLUT-1 was observed in 100% of the samples ranging from 54.2% to 86.2% for the OSCC and 73.9% to 97.4% for the OED. Statistical test revealed that there was greater overexpression of GLUT-1 in OED than the OSCC (p=0.01). It is believed the high expression of GLUT-1 may reflect the involvement of GLUT-1 in early stages of oral carcinogenesis.

Causes, Effects and Possible Solution of Seasonal Egg Gluts: A ...

African Journals Online (AJOL)

A study was conducted to assess small holder poultry farmers' perspectives on the causes, effects and solution to the cyclical egg glut in Ejigbo, Nigeria using questionnaire for data collection and descriptive data analysis. Farmers interviewed agreed that government policies have a registered effect on drop of egg sales ...

O exercício físico é capaz de melhorar expressão de AMPK e GLUT4 em músculo esquelético de ratos alcoolistas e/ou tabagistas

OpenAIRE

Florido Neto, Armando Ribeiro [UNESP

2015-01-01

Alcohol and cigarettes are the lawful psychoactive drugs more consumed in the world, usually being consumed in association. Metabolic alterations are linked to alcohol consumption and tobacco use involving impairment in the expression of proteins related to cellular metabolism. The objective of this study was to evaluate if the regular physical exercise can promote positive effects on the possible impairment related to expression of GLUT4 and AMPK in the skeletal muscle of smoker and/or alcoh...

In vivo inhibition of tumor progression by 5 hydroxy-1,4-naphthoquinone (juglone) and 2-(4-hydroxyanilino)-1,4-naphthoquinone (Q7) in combination with ascorbate

Energy Technology Data Exchange (ETDEWEB)

Ourique, Fabiana [Department of Biochemistry, Universidade Federal de Santa Catarina (UFSC), Florianópolis, SC (Brazil); Kviecinski, Maicon R. [Postgraduate Programe of Health Science, Universidade do Sul de Santa Catarina (UNISUL), Palhoça, SC (Brazil); Zirbel, Guilherme; Castro, Luiza S.E.P.W.; Gomes Castro, Allisson Jhonatan; Mena Barreto Silva, Fátima Regina [Department of Biochemistry, Universidade Federal de Santa Catarina (UFSC), Florianópolis, SC (Brazil); Valderrama, Jaime A.; Rios, David; Benites, Julio [Department of Chemical and Pharmaceutical Sciences, Universidad Arturo Prat, Iquique (Chile); Calderon, Pedro Buc [Toxicology and Cancer Biology Research Group (GTOX), Louvain Drug Research Institute, Université Catholique de Louvain, Brussels (Belgium); Pedrosa, Rozangela Curi, E-mail: rozangelapedrosa@gmail.com [Department of Biochemistry, Universidade Federal de Santa Catarina (UFSC), Florianópolis, SC (Brazil)

2016-09-02

The purpose of the study was to obtain further in vivo data of antitumor effects and mechanisms triggered by juglone and Q7 in combination with ascorbate. The study was done using Ehrlich ascites tumor-bearing mice. Treatments were intraperitoneal every 24 h for 9 days. Control group was treated with excipient. Previous tests selected the doses of juglone and Q7 plus ascorbate (1 and 100 mg/kg, respectively). Samples of ascitic fluid were collected to evaluate carbonyl proteins, GSH and activity of antioxidant enzymes such as catalase, superoxide dismutase, glutathione peroxidase and glutathione reductase. Hypoxia inducible factor HIF-1α, GLUT1, proteins driving cell cycle (p53, p16 and cyclin A) and apoptosis (poly-ADP-polymerase PARP, Bax and Bcl-xL) were assessed by western blot. Tumor cells were categorized by the phase of cell cycle using flow cytometry and type of cell death using acridine orange/ethidium bromide. A glucose uptake assessment was performed by liquid scintillation using Ehrlich tumor cells cultured with {sup 14}C-deoxyglucose. Treatments caused increased protein carbonylation and activity of antioxidant enzymes and decreased levels of GSH, HIF-1α, GLUT1 and glucose uptake in tumor cells. They also caused increased number of tumor cells in G1, p53 and p16 activation and decreased cyclin A, but only when combined with ascorbate. Apoptosis was induced mostly when treatments were done with ascorbate, causing PARP and Bax cleavage, and increased Bax/Bcl-xL ratio. Juglone and Q7 in combination with ascorbate caused inhibition of tumor progress in vivo by triggering apoptosis and cell cycle arrest associated with oxidative stress, suppression of HIF-1 and uncoupling of glycolytic metabolism. - Highlights: • Ascorbate potentiates the inhibition caused by juglone and Q7on tumor progress in vivo. • Juglone and Q7 with ascorbate caused widespread oxidative stress in tumor tissue. • Treatments inhibited HIF-1 and GLUT1 expression causing

Automatically Identifying Fusion Events between GLUT4 Storage Vesicles and the Plasma Membrane in TIRF Microscopy Image Sequences

Directory of Open Access Journals (Sweden)

Jian Wu

2015-01-01

Full Text Available Quantitative analysis of the dynamic behavior about membrane-bound secretory vesicles has proven to be important in biological research. This paper proposes a novel approach to automatically identify the elusive fusion events between VAMP2-pHluorin labeled GLUT4 storage vesicles (GSVs and the plasma membrane. The differentiation is implemented to detect the initiation of fusion events by modified forward subtraction of consecutive frames in the TIRFM image sequence. Spatially connected pixels in difference images brighter than a specified adaptive threshold are grouped into a distinct fusion spot. The vesicles are located at the intensity-weighted centroid of their fusion spots. To reveal the true in vivo nature of a fusion event, 2D Gaussian fitting for the fusion spot is used to derive the intensity-weighted centroid and the spot size during the fusion process. The fusion event and its termination can be determined according to the change of spot size. The method is evaluated on real experiment data with ground truth annotated by expert cell biologists. The evaluation results show that it can achieve relatively high accuracy comparing favorably to the manual analysis, yet at a small fraction of time.

Fanconi Bickel Syndrome: Novel Mutations in GLUT 2 Gene Causing a Distinguished Form of Renal Tubular Acidosis in Two Unrelated Egyptian Families

Directory of Open Access Journals (Sweden)

Mohammad Al-Haggar

2011-01-01

Full Text Available Background. Fanconi-Bickel syndrome (FBS is an autosomal recessive disorder caused by defects in facilitative glucose transporter 2 (GLUT2 or SLC2A2 gene mapped on chromosome 3q26.1-26.3, that codes for the glucose transporter protein 2. Methods. Two unrelated Egyptian families having suspected cases of FBS were enrolled after taking a written informed consent; both had positive consanguinity, and index cases had evidences of proximal renal tubular defects with hepatomegaly; they were subjected to history taking, signs of rickets as well as anthropometric measurements. Laboratory workup included urinalysis, renal and liver function tests including fasting and postprandial blood sugar; serum calcium, phosphorus, alkaline phosphatase, sodium and potassium, lipid profile, and detailed blood gas. Imaging including bone survey and abdominal ultrasound, and liver biopsy were done to confirm diagnosis. Molecular analysis of the GLUT2 gene was done for DNA samples extracted from peripheral blood leukocyte. All coding sequences, including flanking introns in GLUT2 gene, were amplified using PCR followed by direct sequencing. Results. Two new mutations had been detected, one in each family, in exon 3 two bases (GA were deleted (c.253 254delGA and in exon 6 in the second family, G-to-C substitution at position-1 of the splicing acceptor site (c.776-1G>C or IVS5-1G>A. Conclusion. FBS is a rare disease due to mutation in GLUT2 gene; many mutations were reported, about half were novel mutations; yet none of these mutations is more frequent. A more extensive survey for the most frequent mutations among FBS has to be contemplated to allow for use of molecular screening tests like ARMS.

Evolutionary ancestry and novel functions of the mammalian glucose transporter (GLUT) family.

Science.gov (United States)

Wilson-O'Brien, Amy L; Patron, Nicola; Rogers, Suzanne

2010-05-21

In general, sugar porters function by proton-coupled symport or facilitative transport modes. Symporters, coupled to electrochemical energy, transport nutrients against a substrate gradient. Facilitative carriers transport sugars along a concentration gradient, thus transport is dependent upon extracellular nutrient levels. Across bacteria, fungi, unicellular non-vertebrates and plants, proton-coupled hexose symport is a crucial process supplying energy under conditions of nutrient flux. In mammals it has been assumed that evolution of whole body regulatory mechanisms would eliminate this need. To determine whether any isoforms bearing this function might be conserved in mammals, we investigated the relationship between the transporters of animals and the proton-coupled hexose symporters found in other species. We took a comparative genomic approach and have performed the first comprehensive and statistically supported phylogenetic analysis of all mammalian glucose transporter (GLUT) isoforms. Our data reveals the mammalian GLUT proteins segregate into five distinct classes. This evolutionary ancestry gives insight to structure, function and transport mechanisms within the groups. Combined with biological assays, we present novel evidence that, in response to changing nutrient availability and environmental pH, proton-coupled, active glucose symport function is maintained in mammalian cells. The analyses show the ancestry, evolutionary conservation and biological importance of the GLUT classes. These findings significantly extend our understanding of the evolution of mammalian glucose transport systems. They also reveal that mammals may have conserved an adaptive response to nutrient demand that would have important physiological implications to cell survival and growth.

Rosiglitazone stimulates the release and synthesis of insulin by enhancing GLUT-2, glucokinase and BETA2/NeuroD expression

International Nuclear Information System (INIS)

Kim, Hyo-Sup; Noh, Jung-Hyun; Hong, Seung-Hyun; Hwang, You-Cheol; Yang, Tae-Young; Lee, Myung-Shik; Kim, Kwang-Won; Lee, Moon-Kyu

2008-01-01

Peroxisome proliferator-activated receptor (PPAR)-γ is a member of the nuclear receptor superfamily, and its ligands, the thiazolidinediones, might directly stimulate insulin release and insulin synthesis in pancreatic β-cells. In the present study, we examined the effects of rosiglitazone (RGZ) on insulin release and synthesis in pancreatic β-cell (INS-1). Insulin release and synthesis were stimulated by treatment with RGZ for 24 h. RGZ upregulated the expressions of GLUT-2 and glucokinase (GCK). Moreover, it was found that RGZ increased the expression of BETA2/NeuroD gene which could regulate insulin gene expression. These results suggest that RGZ could stimulate the release and synthesis of insulin through the upregulation of GLUT-2, GCK, and BETA2/NeuroD gene expression

Evolutionary ancestry and novel functions of the mammalian glucose transporter (GLUT family

Directory of Open Access Journals (Sweden)

Patron Nicola

2010-05-01

Full Text Available Abstract Background In general, sugar porters function by proton-coupled symport or facilitative transport modes. Symporters, coupled to electrochemical energy, transport nutrients against a substrate gradient. Facilitative carriers transport sugars along a concentration gradient, thus transport is dependent upon extracellular nutrient levels. Across bacteria, fungi, unicellular non-vertebrates and plants, proton-coupled hexose symport is a crucial process supplying energy under conditions of nutrient flux. In mammals it has been assumed that evolution of whole body regulatory mechanisms would eliminate this need. To determine whether any isoforms bearing this function might be conserved in mammals, we investigated the relationship between the transporters of animals and the proton-coupled hexose symporters found in other species. Results We took a comparative genomic approach and have performed the first comprehensive and statistically supported phylogenetic analysis of all mammalian glucose transporter (GLUT isoforms. Our data reveals the mammalian GLUT proteins segregate into five distinct classes. This evolutionary ancestry gives insight to structure, function and transport mechanisms within the groups. Combined with biological assays, we present novel evidence that, in response to changing nutrient availability and environmental pH, proton-coupled, active glucose symport function is maintained in mammalian cells. Conclusions The analyses show the ancestry, evolutionary conservation and biological importance of the GLUT classes. These findings significantly extend our understanding of the evolution of mammalian glucose transport systems. They also reveal that mammals may have conserved an adaptive response to nutrient demand that would have important physiological implications to cell survival and growth.

Pulsatile Hyperglycaemia Induces Vascular Oxidative Stress and GLUT 1 Expression More Potently than Sustained Hyperglycaemia in Rats on High Fat Diet

DEFF Research Database (Denmark)

Rakipovski, Gunaj; Lykkesfeldt, Jens; Raun, Kirsten

2016-01-01

expression of glucose transporter 1 (GLUT1), gp-91(PHOX) and super oxide dismutase (SOD), while only the PLG group showed increased accumulation of oxidative stress and oxidised low density lipoprotein (oxLDL) in aorta. Conclusion Pulsatile hyperglycaemia induced relatively higher levels of oxidative stress......Introduction Pulsatile hyperglycaemia resulting in oxidative stress may play an important role in the development of macrovascular complications. We investigated the effects of sustained vs. pulsatile hyperglycaemia in insulin resistant rats on markers of oxidative stress, enzyme expression...... and glucose metabolism in liver and aorta. We hypothesized that liver's ability to regulate the glucose homeostasis under varying states of hyperglycaemia may indirectly affect oxidative stress status in aorta despite the amount of glucose challenged with. Methods Animals were infused with sustained high (SHG...

Inhibition of Glucose Transport by Tomatoside A, a Tomato Seed Steroidal Saponin, through the Suppression of GLUT2 Expression in Caco-2 Cells.

Science.gov (United States)

Li, Baorui; Terazono, Yusuke; Hirasaki, Naoto; Tatemichi, Yuki; Kinoshita, Emiko; Obata, Akio; Matsui, Toshiro

2018-02-14

We investigated whether tomatoside A (5α-furostane-3β,22,26-triol-3-[O-β-d-glucopyranosyl (1→2)-β-d-glucopyranosyl (1→4)-β-d-galactopyranoside] 26-O-β-d-glucopyranoside), a tomato seed saponin, may play a role in the regulation of intestinal glucose transport in human intestinal Caco-2 cells. Tomatoside A could not penetrate through Caco-2 cell monolayers, as observed in the transport experiments using liquid chromatography-mass spectrometry. The treatment of cells with 10 μM tomatoside A for 3 h resulted in a 46.0% reduction in glucose transport as compared to untreated cells. Western blotting analyses revealed that tomatoside A significantly (p transporter 2 (GLUT2) in Caco-2 cells, while no change in the expression of sodium-dependent glucose transporter 1 was observed. In glucose transport experiments, the reduced glucose transport by tomatoside A was ameliorated by a protein kinase C (PKC) inhibitor and a multidrug resistance-associated protein 2 (MRP2) inhibitor. The tomatoside A-induced reduction in glucose transport was restored in cells treated with apical sodium-dependent bile acid transporter (ASBT) siRNA or an ASBT antagonist. These findings demonstrated for the first time that the nontransportable tomato seed steroidal saponin, tomatoside A, suppressed GLUT2 expression via PKC signaling pathway during the ASBT-influx/MRP2-efflux process in Caco-2 cells.

A novel role for myosin II in insulin-stimulated glucose uptake in 3T3-L1 adipocytes

International Nuclear Information System (INIS)

Steimle, Paul A.; Kent Fulcher, F.; Patel, Yashomati M.

2005-01-01

Insulin-stimulated glucose uptake requires the activation of several signaling pathways to mediate the translocation and fusion of GLUT4 vesicles from an intracellular pool to the plasma membrane. The studies presented here show that inhibition of myosin II activity impairs GLUT4-mediated glucose uptake but not GLUT4 translocation to the plasma membrane. We also show that adipocytes express both myosin IIA and IIB isoforms, and that myosin IIA is recruited to the plasma membrane upon insulin stimulation. Taken together, the data presented here represent the first demonstration that GLUT4-mediated glucose uptake is a myosin II-dependent process in adipocytes. Based on our findings, we hypothesize that myosin II is activated upon insulin stimulation and recruited to the cell cortex to facilitate GLUT4 fusion with the plasma membrane. The identification of myosin II as a key component of GLUT4-mediated glucose uptake represents an important advance in our understanding of the mechanisms regulating glucose homeostasis

Glukosetransporter 1-mangelsyndrom har et varieret klinisk billede

DEFF Research Database (Denmark)

Larsen, Jan; Stubbings, Vibeke; Møller, Rikke Steensbjerre

2014-01-01

Glucose transporter-1 deficiency syndrome (GLUT1-DS) is caused by a decreased function of the glucose transporter GLUT1 protein, which is located in the blood brain barrier. This leads to inadequate glucose levels for brain metabolism and can cause various clinical symptoms including medically...... intractable epilepsy, developmental delay and complex movement disorders. Ketonic diet is the golden standard for treatment of GLUT1-DS. GLUT1-DS should be suspected in patients with early-onset intractable epilepsy with developmental delay or activity-induced movement disorders with or without epilepsy....

The prognostic value of the hypoxia markers CA IX and GLUT 1 and the cytokines VEGF and IL 6 in head and neck squamous cell carcinoma treated by radiotherapy ± chemotherapy

International Nuclear Information System (INIS)

De Schutter, Harlinde; Landuyt, Willy; Verbeken, Erik; Goethals, Laurence; Hermans, Robert; Nuyts, Sandra

2005-01-01

Several parameters of the tumor microenvironment, such as hypoxia, inflammation and angiogenesis, play a critical role in tumor aggressiveness and treatment response. A major question remains if these markers can be used to stratify patients to certain treatment protocols. The purpose of this study was to investigate the inter-relationship and the prognostic significance of several biological and clinicopathological parameters in patients with head and neck squamous cell carcinoma (HNSCC) treated by radiotherapy ± chemotherapy. We used two subgroups of a retrospective series for which CT-determined tumoral perfusion correlated with local control. In the first subgroup (n = 67), immunohistochemistry for carbonic anhydrase IX (CA IX) and glucose transporter-1 (GLUT-1) was performed on the pretreatment tumor biopsy. In the second subgroup (n = 34), enzyme linked immunosorbent assay (ELISA) was used to determine pretreatment levels of the cytokines vascular endothelial growth factor (VEGF) and interleukin-6 (IL-6) in serum. Correlation was investigated between tumoral perfusion and each of these biological markers, as well as between the markers mutually. The prognostic value of these microenvironmental parameters was also evaluated. For CA IX and GLUT-1, the combined assessment of patients with both markers expressed above the median showed an independent correlation with local control (p = 0.02) and disease-free survival (p = 0.04) with a trend for regional control (p = 0.06). In the second subgroup, IL-6 pretreatment serum level above the median was the only independent predictor of local control (p = 0.009), disease-free survival (p = 0.02) and overall survival (p = 0.005). To our knowledge, we are the first to report a link in HNSCC between IL-6 pretreatment serum levels and radioresistance in vivo. This link is supported by the strong prognostic association of pretreatment IL-6 with local control, known to be the most important parameter to judge radiotherapy

Difference in transient ischemia-induced neuronal damage and glucose transporter-1 immunoreactivity in the hippocampus between adult and young gerbils

Directory of Open Access Journals (Sweden)

Seung Min Park

2016-05-01

Full Text Available Objective(s: The alteration of glucose transporters is closely related with the pathogenesis of brain edema. We compared neuronal damage/death in the hippocampus between adult and young gerbils following transient cerebral ischemia/reperfusion and changes of glucose transporter-1(GLUT-1-immunoreactive microvessels in their ischemic hippocampal CA1 region. Materials and Methods: Transient cerebral ischemia was developed by 5-min occlusion of both common carotid arteries. Neuronal damage was examined by cresyl violet staining, NeuN immunohistochemistry and Fluoro-Jade B histofluorescence staining and changes in GLUT-1 expression was carried out by immunohistochemistry. Results: About 90% of pyramidal neurons only in the adult CA1 region were damaged after ischemia/reperfusion; in the young, about 53 % of pyramidal neurons were damaged from 7 days after ischemia/reperfusion. The density of GLUT-1-immunoreactive microvessels was significantly higher in the young sham-group than that in the adult sham-group. In the ischemia-operated-groups, the density of GLUT-1-immunoreactive microvessels was significantly decreased in the adult and young at 1 and 4 days post-ischemia, respectively, thereafter, the density of GLUT-1-immunoreactive microvessels was gradually increased in both groups after ischemia/reperfusion. Conclusion: CA1 pyramidal neurons of the young gerbil were damaged much later than that in the adult and that GLUT-1-immunoreactive microvessels were significantly decreased later in the young. These data indicate that GLUT-1 might differently contribute to neuronal damage according to age after ischemic insults.

(19)F-heptuloses as tools for the non-invasive imaging of GLUT2-expressing cells

DEFF Research Database (Denmark)

Malaisse, Willy J; Zhang, Ying; Louchami, Karim

2012-01-01

Suitable analogs of d-mannoheptulose are currently considered as possible tools for the non-invasive imaging of pancreatic islet insulin-producing cells. Here, we examined whether (19)F-heptuloses could be used for non-invasive imaging of GLUT2-expressing cells. After 20 min incubation, the uptake......-mannoheptulose in inhibiting insulin release. The 1-deoxy-1-fluoro-d-mannoheptulose and 3-deoxy-3-fluoro-d-mannoheptulose only marginally affected INS-1 cell viability. These findings are compatible with the view that selected (19)F-heptuloses may represent suitable tools for the non-invasive imaging of hepatocytes...

Effects of rhizoma polygonati on the expression of glucose transporter-4 gene in type 2 diabetes mellitus rats with insulin resistance%黄精对2型糖尿病胰岛素抵抗大鼠葡萄糖转运蛋白-4基因表达的影响

Institute of Scientific and Technical Information of China (English)

董琦; 董凯; 张春军

2012-01-01

Objective To observe the effects of rhizoma polygonati( RP) on the expression of glucose transporter-4 (GLUT-4) gene in muscular tissue in type 2 diabetes mellitus(T2DM) rats with insulin resistance(IR). Methods The model of T2DM rats with insulin resistance was established by giving high fat, high caloric diet and injection of small dose of strep-tozotocin(STZ). The model rats were divided into model control group, high, middle and low doses RP groups( inlragastric administration 10.0,5.0,2.5 g o kg-1 o d-1 RP). Other 10 rats were selected as normal control group. After intragastric administration for eight weeks,then the GLUT-4 mRNA in muscular tissue was determined by reverse transcription-polymerase chain reaction(RT-PCR). Results Compared with normal control group,the expressions of GLUT-4 mRNA were lower(P <0.01), but the levels of fasting plasma glucose(FPG) were higher(P <0. 01) in model control group,low,middle and high doses RP groups. Compared with model control group,the levels of FPG were lower in low,middle and high doses RP groups,and the decreasing level in middle and high doses RP groups was obviously( P < 0.01 ) ; the expressions of GLUT-4 mRNA were higher in low,middle and high doses RP groups,and the increasing level in middle and high doses RP groups was obviously(P<0.01 ). Conclusion RP can reduce blood glucose by increasing expression of GLUT-4 mRNA in T2DM rats with IR.%目的 观察黄精水提液对2型糖尿病(T2DM)胰岛素抵抗大鼠肌肉组织葡萄糖转运蛋白-4(GLUT-4)基因表达的影响.方法 采用小剂量链脲佐菌素加高脂高热量饲料喂养方法建立2型糖尿病胰岛素抵抗模型,将造模大鼠随机分为模型对照组和黄精高、中、低剂量治疗组(分别灌胃10.0、5.0、2.5g·kg-1·d-1),另选10只为正常对照组.灌胃8周后,空腹取材,反转录-聚合酶链反应法检测肌肉组织GLUT-4基因mRNA水平.结果 与正常对照组相比,模型对照组及黄精高、中、低剂量治疗组大鼠GLUT

Polymorphisms in sweet taste genes (TAS1R2 and GLUT2), sweet liking, and dental caries prevalence in an adult Italian population.

Science.gov (United States)

Robino, Antonietta; Bevilacqua, Lorenzo; Pirastu, Nicola; Situlin, Roberta; Di Lenarda, Roberto; Gasparini, Paolo; Navarra, Chiara Ottavia

2015-09-01

The aim of the study was to assess the relationship between sweet taste genes and dental caries prevalence in a large sample of adults. In addition, the association between sweet liking and sugar intake with dental caries was investigated. Caries was measured by the decayed, missing, filled teeth (DMFT) index in 647 Caucasian subjects (285 males and 362 females, aged 18-65 years), coming from six villages in northeastern Italy. Sweet liking was assessed using a 9-point scale, and the mean of the liking given by each individual to specific sweet food and beverages was used to create a sweet liking score. Simple sugar consumption was estimated by a dietary history interview, considering both added sugars and sugar present naturally in foods. Our study confirmed that polymorphisms in TAS1R2 and GLUT2 genes are related to DMFT index. In particular, GG homozygous individuals for rs3935570 in TAS1R2 gene (p value = 0.0117) and GG homozygous individuals for rs1499821 in GLUT2 gene (p value = 0.0273) showed higher DMFT levels compared to both heterozygous and homozygous for the alternative allele. Furthermore, while the relationship sugar intake-DMFT did not achieve statistical significance (p value = 0.075), a significant association was identified between sweet liking and DMFT (p value = 0.004), independent of other variables. Our study showed that sweet taste genetic factors contribute to caries prevalence and highlighted the role of sweet liking as a predictor of caries risk. Therefore, these results may open new perspectives for individual risk identification and implementation of target preventive strategies, such as identifying high-risk patients before caries development.

Thermal properties of silica-filled high density polyethylene composites compatibilized with glut palmitate

Science.gov (United States)

Samsudin, Dalina; Ismail, Hanafi; Othman, Nadras; Hamid, Zuratul Ain Abdul

2017-07-01

A study of thermal properties resulting from the utilization of Glut Palmitate (GP) on the silica filled high density polyethylene (HDPE) composites was carried out. The composites with the incorporation of GP at 0.5, 1.0, 2.0 and 3.0 phr were prepared by using an internal mixer at the temperature 180 °C and the rotor speed of 50 rpm. The thermal behaviours of the composites were then investigated using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). It was found that the crystallinity and the thermal stability of the composites increased with the incorporation of GP. The highest crystallinity contents and decomposition temperatures were observed at the 1 phr GP loading.

Glucose transporter expression in human skeletal muscle fibers

DEFF Research Database (Denmark)

Gaster, M; Handberg, A; Beck-Nielsen, H

2000-01-01

, but its expression is markedly reduced around birth and is further reduced to undetectable levels within the first year of life; 2) GLUT-3 protein expression appears at 18 wk of gestation and disappears after birth; and 3) GLUT-4 protein is diffusely expressed in muscle cells throughout gestation, whereas...... after birth, the characteristic subcellular localization is as seen in adult muscle fibers. Our results show that GLUT-1, GLUT-3, and GLUT-4 seem to be of importance during muscle fiber growth and development. GLUT-5 protein was undetectable in fetal and adult skeletal muscle fibers. In adult muscle...... amplification (TSA) technique to detect the localization of glucose transporter expression in human skeletal muscle. We found expression of GLUT-1, GLUT-3, and GLUT-4 in developing human muscle fibers showing a distinct expression pattern. 1) GLUT-1 is expressed in human skeletal muscle cells during gestation...

Glucose availability controls adipogenesis in mouse 3T3-L1 adipocytes via up-regulation of nicotinamide metabolism.

Science.gov (United States)

Jackson, Robert M; Griesel, Beth A; Gurley, Jami M; Szweda, Luke I; Olson, Ann Louise

2017-11-10

Expansion of adipose tissue in response to a positive energy balance underlies obesity and occurs through both hypertrophy of existing cells and increased differentiation of adipocyte precursors (hyperplasia). To better understand the nutrient signals that promote adipocyte differentiation, we investigated the role of glucose availability in regulating adipocyte differentiation and maturation. 3T3-L1 preadipocytes were grown and differentiated in medium containing a standard differentiation hormone mixture and either 4 or 25 mm glucose. Adipocyte maturation at day 9 post-differentiation was determined by key adipocyte markers, including glucose transporter 4 (GLUT4) and adiponectin expression and Oil Red O staining of neutral lipids. We found that adipocyte differentiation and maturation required a pulse of 25 mm glucose only during the first 3 days of differentiation. Importantly, fatty acids were unable to substitute for the 25 mm glucose pulse during this period. The 25 mm glucose pulse increased adiponectin and GLUT4 expression and accumulation of neutral lipids via distinct mechanisms. Adiponectin expression and other early markers of differentiation required an increase in the intracellular pool of total NAD/P. In contrast, GLUT4 protein expression was only partially restored by increased NAD/P levels. Furthermore, GLUT4 mRNA expression was mediated by glucose-dependent activation of GLUT4 gene transcription through the cis-acting GLUT4-liver X receptor element (LXRE) promoter element. In summary, this study supports the conclusion that high glucose promotes adipocyte differentiation via distinct metabolic pathways and independently of fatty acids. This may partly explain the mechanism underlying adipocyte hyperplasia that occurs much later than adipocyte hypertrophy in the development of obesity. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

The Global Saving Glut in the light of demographic developments : a numerical simulation of the developments in China and the US

OpenAIRE

Pettersen, Malin Karlberg; Håland, Marianne

2016-01-01

The objective of this thesis is to predict how demographic developments will affect the Global Saving Glut. The thesis examines how the changes in the age structure in China and the US are affecting their respective aggregate savings rates. Ben Bernanke was the first economist to mention the term Global Saving Glut, which describes an economy where desired saving exceeds desired investment. He states that the increase in the global supply of savings was one of the main reasons ...

An efficient co-expression and purification system for the complex of Stx4 and C-terminal domain of Synip

International Nuclear Information System (INIS)

Tian Wei; Ma Cong; Liu Yingfang; Xu Tao

2008-01-01

Synip and Stx4 complex plays a key role in GLUT4 vesicle trafficking and fusion with plasma membrane. The interaction of Synip with Stx4 prevents interaction of VAMP2 located in GLUT4 vesicle with Stx4 in basal state. Insulin induces the dissociation of the Synip and Stx4 complex, and then triggers VAMP2 to interact with Stx4 to form the SNARE complex, thus promoting the vesicle fusion. In this report, we adopt a novel system for co-expression of the Synip and Stx4 by using two common vectors pGEX6p-1 and pET28a(+) to investigate their expression, purification, and interaction. Through this co-expression system, we successfully co-expressed the Synip and Stx4 complex with high yield, and co-purified at an approximate 1:1 molar ratio with high purity (95%). We also demonstrate that the 1-28 residues of Stx4 are dispensable for interaction with Synip using this co-expression system

Chronic intermittent hypoxia from pedo-stage decreases glucose transporter 4 expression in adipose tissue and causes insulin resistance.

Science.gov (United States)

Chen, Lin; Cao, Zhao-long; Han, Fang; Gao, Zhan-cheng; He, Quan-ying

2010-02-20

The persistence of sleep disordered breathing (SDB) symptoms after tonsil and/or adenoid (T&A) surgery are common in children with obstructive sleep apnea (OSA). We tested the hypothesis that disturbances of glucose transporters (GLUTs) in intraabdominal adipose tissue caused by chronic intermittent hypoxia (CIH) from the pedo-period could facilitate the appearance of periphery insulin resistance in Sprague-Dawley (SD) rats. We tested the hypothesis that the changes of GLUTs in adipose tissue may be one of the reasons for persistent SDB among clinical OSA children after T&A surgery. Thirty 21-day-old SD rats were randomly divided into a CIH group, a chronic continuous hypoxia (CCH) group, and a normal oxygen group (control group) and exposed for 40 days. The changes of weight, fasting blood glucose and fasting blood insulin levels were measured. Hyperinsulinemic-euglycemic clamp techniques were used to measure insulin resistance in each animal. Real-time quantitative PCR and Western blotting were used to measure GLUT mRNA and proteins in intraabdominal adipose tissue. Additional intraabdomial white adipose tissue (WAT) was also processed into paraffin sections and directly observed for GLUTs1-4 expression. When compared with control group, CIH increased blood fasting insulin levels, (245.07 +/- 53.89) pg/ml vs. (168.63 +/- 38.70) pg/ml, P = 0.038, and decreased the mean glucose infusion rate (GIR), (7.25 +/- 1.29) mg x kg(-1) x min(-1) vs. (13.34 +/- 1.54) mg x kg(-1) x min(-1), P < 0.001. GLUT-4 mRNA and protein expression was significantly reduced after CIH compared with CCH or normal oxygen rats, 0.002 +/- 0.002 vs. 0.039 +/- 0.009, P < 0.001; 0.642 +/- 0.073 vs. 1.000 +/- 0.103, P = 0.035. CIH in young rats could induce insulin resistance via adverse effects on glycometabolism. These findings emphasize the importance of early detection and treatment of insulin insensitivity in obese childhood OSA.

Genetic and nongenetic determinants of skeletal muscle glucose transporter 4 messenger ribonucleic acid levels and insulin action in twins

DEFF Research Database (Denmark)

Storgaard, Heidi; Poulsen, Pernille; Ling, Charlotte

2006-01-01

-stimulated expressions of GLUT4 were independently and significantly related to whole-body in vivo insulin action, nonoxidative glucose metabolism, and glucose oxidation. CONCLUSION: We show that skeletal muscle GLUT4 gene expression in twins is significantly and independently related to glucose metabolism...

Glucose Transporters in Diabetic Kidney Disease-Friends or Foes?

Science.gov (United States)

Wasik, Anita A; Lehtonen, Sanna

2018-01-01

Diabetic kidney disease (DKD) is a major microvascular complication of diabetes and a common cause of end-stage renal disease worldwide. DKD manifests as an increased urinary protein excretion (albuminuria). Multiple studies have shown that insulin resistance correlates with the development of albuminuria in non-diabetic and diabetic patients. There is also accumulating evidence that glomerular epithelial cells or podocytes are insulin sensitive and that insulin signaling in podocytes is essential for maintaining normal kidney function. At the cellular level, the mechanisms leading to the development of insulin resistance include mutations in the insulin receptor gene, impairments in the phosphoinositide 3-kinase (PI3K)/AKT signaling pathway, or perturbations in the trafficking of glucose transporters (GLUTs), which mediate the uptake of glucose into cells. Podocytes express several GLUTs, including GLUT1, GLUT2, GLUT3, GLUT4, and GLUT8. Of these, the most studied ones are GLUT1 and GLUT4, both shown to be insulin responsive in podocytes. In the basal state, GLUT4 is preferentially located in perinuclear and cytosolic vesicular structures and to a lesser extent at the plasma membrane. After insulin stimulation, GLUT4 is sorted into GLUT4-containing vesicles (GCVs) that translocate to the plasma membrane. GCV trafficking consists of several steps, including approaching of the GCVs to the plasma membrane, tethering, and docking, after which the lipid bilayers of the GCVs and the plasma membrane fuse, delivering GLUT4 to the cell surface for glucose uptake into the cell. Studies have revealed novel molecular regulators of the GLUT trafficking in podocytes and unraveled unexpected roles for GLUT1 and GLUT4 in the development of DKD, summarized in this review. These findings pave the way for better understanding of the mechanistic pathways associated with the development and progression of DKD and aid in the development of new treatments for this devastating disease.

Glucose transporter type 1 deficiency syndrome with carbohydrate-responsive symptoms but without epilepsy.

Science.gov (United States)

Koy, Anne; Assmann, Birgit; Klepper, Joerg; Mayatepek, Ertan

2011-12-01

Glucose transporter type 1 deficiency syndrome (GLUT1-DS) is caused by a defect in glucose transport across the blood-brain barrier. The main symptoms are epilepsy, developmental delay, movement disorders, and deceleration of head circumference. A ketogenic diet has been shown to be effective in controlling epilepsy in GLUT1-DS. We report a female child (3 y 4 mo) who presented with delayed psychomotor development and frequent episodes of staggering, impaired vigilance, and vomiting that resolved promptly after food intake. Electroencephalography was normal. The cerebrospinal fluid-blood glucose ratio was 0.42 (normal ≥ 0.45). GLUT1-DS was confirmed by molecular genetic testing, which showed a novel de novo heterozygous mutation in the SLC2A1 gene (c.497_499delTCG, p.VAL166del). Before starting a ketogenic diet, the child's cognitive development was tested using the Snijders-Oomen Non-Verbal Intelligence Test, which revealed a heterogeneous intelligence profile with deficits in her visuomotor skills and spatial awareness. Her motor development was delayed. Three months after introducing a ketogenic diet, she showed marked improvement in speech and motor development, as tested by the Movement Assessment Battery for Children (manual dexterity 16th centile, ball skills 1st centile, static and dynamic balance 5th centile). This case demonstrates that GLUT1-DS should be investigated in individuals with unexplained developmental delay. Epilepsy is not a mandatory symptom. The ketogenic diet is also beneficial for non-epileptic symptoms in GLUT1-DS. © The Authors. Developmental Medicine & Child Neurology © 2011 Mac Keith Press.

Arachidonic acid and lipoxin A4 attenuate alloxan-induced cytotoxicity to RIN5F cells in vitro and type 1 diabetes mellitus in vivo.

Science.gov (United States)

Gundala, Naveen K V; Naidu, Vegi G M; Das, Undurti N

2017-03-01

We studied whether polyunsaturated fatty acids (PUFAs) can protect rat insulinoma (RIN5F) cells against alloxan-induced apoptosis in vitro and type 1 diabetes mellitus (type 1 DM) in vivo and if so, mechanism of this beneficial action. In vitro study was conducted using RIN5F cells while in vivo study was performed in Wistar rats. The effect of PUFAs, cyclo-oxygenase and lipoxygenase inhibitors, various eicosanoids and PUFAs metabolites: lipoxin A4 (LXA4), resolvin D2 and protectin against alloxan-induced cytotoxicity to RIN5F cells and type 1 DM was studied. Expression of PDX1, P65 NF-kB and IKB in RIN5F cells and Nrf2, GLUT2, COX2, iNOS protein levels in the pancreatic tissue and plasma glucose, insulin and tumor necrosis factor-α and antioxidants, lipid peroxides and nitric oxide were measured. Of all, arachidonic acid (AA) was found to be the most effective against alloxan-induced cytotoxicity to RIN5F cells and preventing type 1 DM. Both cyclo-oxygenase and lipoxygenase inhibitors did not block the beneficial actions of AA in vitro and in vivo. Alloxan inhibited LXA4 production by RIN5F cells and in alloxan-induced type 1 DM Wistar rats. AA-treatment restored LXA4 levels to normal both in vitro and in vivo. LXA4 protected RIN5F cells against alloxan-induced cytotoxicity and prevented type 1 DM and restored expression of Nrf2, Glut2, COX2, and iNOS genes and abnormal antioxidants to near normal. AA seems to bring about its beneficial actions against alloxan-induced cytotoxicity and type 1 DM by enhancing the production of LXA4. © 2016 BioFactors, 43(2):251-271, 2017. © 2016 International Union of Biochemistry and Molecular Biology.

Elucidation of the glucose transport pathway in glucose transporter 4 via steered molecular dynamics simulations.

Directory of Open Access Journals (Sweden)

Aswathy Sheena

Full Text Available BACKGROUND: GLUT4 is a predominant insulin regulated glucose transporter expressed in major glucose disposal tissues such as adipocytes and muscles. Under the unstimulated state, GLUT4 resides within intracellular vesicles. Various stimuli such as insulin translocate this protein to the plasma membrane for glucose transport. In the absence of a crystal structure for GLUT4, very little is known about the mechanism of glucose transport by this protein. Earlier we proposed a homology model for GLUT4 and performed a conventional molecular dynamics study revealing the conformational rearrangements during glucose and ATP binding. However, this study could not explain the transport of glucose through the permeation tunnel. METHODOLOGY/PRINCIPAL FINDINGS: To elucidate the molecular mechanism of glucose transport and its energetic, a steered molecular dynamics study (SMD was used. Glucose was pulled from the extracellular end of GLUT4 to the cytoplasm along the pathway using constant velocity pulling method. We identified several key residues within the tunnel that interact directly with either the backbone ring or the hydroxyl groups of glucose. A rotation of glucose molecule was seen near the sugar binding site facilitating the sugar recognition process at the QLS binding site. CONCLUSIONS/SIGNIFICANCE: This study proposes a possible glucose transport pathway and aids the identification of several residues that make direct interactions with glucose during glucose transport. Mutational studies are required to further validate the observation made in this study.

Studi Distribusi Glukosa Transporter 4 pada Otot Skelet Ayam Kedu Cemani

OpenAIRE

Budipitojo, Teguh; -, Ariana; Pangestiningsih, Tri Wahyu; Wijayanto, Hery; Kusindarta, Dwi Liliek; Musana, Dewi Kania

2017-01-01

Glucose transporter (GLUT 4) is glucose transporter protein regulated by insulin, found in adipose tissue and striated muscle (skeletal and cardiac muscle). Kedu cemani chicken is one of Indonesia endemic animal, found in Kedu, Temanggung regency, Central Java. This study was required to complete microscopic documentation of  Indonesia’s native biodiversity. The objective of this study was to clarify GLUT 4 distribution in skeletal muscle fibers of kedu cemani chicken by using avidin-biotin-p...

Septin 7 reduces nonmuscle myosin IIA activity in the SNAP23 complex and hinders GLUT4 storage vesicle docking and fusion

Energy Technology Data Exchange (ETDEWEB)

Wasik, Anita A.; Dumont, Vincent [Department of Pathology, University of Helsinki, 00014 Helsinki (Finland); Tienari, Jukka [Department of Pathology, University of Helsinki and Helsinki University Hospital, 00290 Helsinki, 05850 Hyvinkää (Finland); Nyman, Tuula A. [Institute of Biotechnology, University of Helsinki, 00014 Helsinki (Finland); Fogarty, Christopher L.; Forsblom, Carol; Lehto, Markku [Folkhälsan Institute of Genetics, Folkhälsan Research Center, 00290 Helsinki (Finland); Abdominal Center Nephrology, University of Helsinki and Helsinki University Hospital, 000290 Helsinki (Finland); Diabetes& Obesity Research Program, Research Program´s Unit, 00014 University of Helsinki (Finland); Lehtonen, Eero [Department of Pathology, University of Helsinki, 00014 Helsinki (Finland); Laboratory Animal Centre, University of Helsinki, 00014 Helsinki (Finland); Groop, Per-Henrik [Folkhälsan Institute of Genetics, Folkhälsan Research Center, 00290 Helsinki (Finland); Abdominal Center Nephrology, University of Helsinki and Helsinki University Hospital, 000290 Helsinki (Finland); Diabetes& Obesity Research Program, Research Program´s Unit, 00014 University of Helsinki (Finland); Baker IDI Heart & Diabetes Institute, 3004 Melbourne (Australia); Lehtonen, Sanna, E-mail: sanna.h.lehtonen@helsinki.fi [Department of Pathology, University of Helsinki, 00014 Helsinki (Finland)

2017-01-15

Glomerular epithelial cells, podocytes, are insulin responsive and can develop insulin resistance. Here, we demonstrate that the small GTPase septin 7 forms a complex with nonmuscle myosin heavy chain IIA (NMHC-IIA; encoded by MYH9), a component of the nonmuscle myosin IIA (NM-IIA) hexameric complex. We observed that knockdown of NMHC-IIA decreases insulin-stimulated glucose uptake into podocytes. Both septin 7 and NM-IIA associate with SNAP23, a SNARE protein involved in GLUT4 storage vesicle (GSV) docking and fusion with the plasma membrane. We observed that insulin decreases the level of septin 7 and increases the activity of NM-IIA in the SNAP23 complex, as visualized by increased phosphorylation of myosin regulatory light chain. Also knockdown of septin 7 increases the activity of NM-IIA in the complex. The activity of NM-IIA is increased in diabetic rat glomeruli and cultured human podocytes exposed to macroalbuminuric sera from patients with type 1 diabetes. Collectively, the data suggest that the activity of NM-IIA in the SNAP23 complex plays a key role in insulin-stimulated glucose uptake into podocytes. Furthermore, we observed that septin 7 reduces the activity of NM-IIA in the SNAP23 complex and thereby hinders GSV docking and fusion with the plasma membrane. - Highlights: • Septin 7, nonmuscle myosin heavy chain IIA (NMHC-IIA) and SNAP23 form a complex. • Knockdown of septin 7 increases NM-IIA activity in the SNAP23 complex. • Insulin decreases septin 7 level and increases NM-IIA activity in the SNAP23 complex. • Septin 7 hinders GSV docking/fusion by reducing NM-IIA activity in the SNAP23 complex.

Septin 7 reduces nonmuscle myosin IIA activity in the SNAP23 complex and hinders GLUT4 storage vesicle docking and fusion

International Nuclear Information System (INIS)

Wasik, Anita A.; Dumont, Vincent; Tienari, Jukka; Nyman, Tuula A.; Fogarty, Christopher L.; Forsblom, Carol; Lehto, Markku; Lehtonen, Eero; Groop, Per-Henrik; Lehtonen, Sanna

2017-01-01

Glomerular epithelial cells, podocytes, are insulin responsive and can develop insulin resistance. Here, we demonstrate that the small GTPase septin 7 forms a complex with nonmuscle myosin heavy chain IIA (NMHC-IIA; encoded by MYH9), a component of the nonmuscle myosin IIA (NM-IIA) hexameric complex. We observed that knockdown of NMHC-IIA decreases insulin-stimulated glucose uptake into podocytes. Both septin 7 and NM-IIA associate with SNAP23, a SNARE protein involved in GLUT4 storage vesicle (GSV) docking and fusion with the plasma membrane. We observed that insulin decreases the level of septin 7 and increases the activity of NM-IIA in the SNAP23 complex, as visualized by increased phosphorylation of myosin regulatory light chain. Also knockdown of septin 7 increases the activity of NM-IIA in the complex. The activity of NM-IIA is increased in diabetic rat glomeruli and cultured human podocytes exposed to macroalbuminuric sera from patients with type 1 diabetes. Collectively, the data suggest that the activity of NM-IIA in the SNAP23 complex plays a key role in insulin-stimulated glucose uptake into podocytes. Furthermore, we observed that septin 7 reduces the activity of NM-IIA in the SNAP23 complex and thereby hinders GSV docking and fusion with the plasma membrane. - Highlights: • Septin 7, nonmuscle myosin heavy chain IIA (NMHC-IIA) and SNAP23 form a complex. • Knockdown of septin 7 increases NM-IIA activity in the SNAP23 complex. • Insulin decreases septin 7 level and increases NM-IIA activity in the SNAP23 complex. • Septin 7 hinders GSV docking/fusion by reducing NM-IIA activity in the SNAP23 complex.

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

Science.gov (United States)

Vera-Sirera, Beatriz; Forner-Navarro, Leopoldo; Vera-Sempere, Francisco

2016-03-10

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

Insulin stimulation regulates AS160 and TBC1D1 phosphorylation sites in human skeletal muscle

DEFF Research Database (Denmark)

Middelbeek, R J W; Chambers, M A; Tantiwong, P

2013-01-01

Individuals with obesity and type 2 diabetes (T2D) are typically insulin resistant, exhibiting impaired skeletal muscle glucose uptake. Animal and cell culture experiments have shown that site-specific phosphorylation of the Rab-GTPase-activating proteins AS160 and TBC1D1 is critical for GLUT4 tr...

Glucose transporter expression in an avian nectarivore: the ruby-throated hummingbird (Archilochus colubris.

Directory of Open Access Journals (Sweden)

Kenneth C Welch

Full Text Available Glucose transporter (GLUT proteins play a key role in the transport of monosaccharides across cellular membranes, and thus, blood sugar regulation and tissue metabolism. Patterns of GLUT expression, including the insulin-responsive GLUT4, have been well characterized in mammals. However, relatively little is known about patterns of GLUT expression in birds with existing data limited to the granivorous or herbivorous chicken, duck and sparrow. The smallest avian taxa, hummingbirds, exhibit some of the highest fasted and fed blood glucose levels and display an unusual ability to switch rapidly and completely between endogenous fat and exogenous sugar to fuel energetically expensive hovering flight. Despite this, nothing is known about the GLUT transporters that enable observed rapid rates of carbohydrate flux. We examined GLUT (GLUT1, 2, 3, & 4 expression in pectoralis, leg muscle, heart, liver, kidney, intestine and brain from both zebra finches (Taeniopygia guttata and ruby-throated hummingbirds (Archilochus colubris. mRNA expression of all four transporters was probed using reverse-transcription PCR (RT-PCR. In addition, GLUT1 and 4 protein expression were assayed by western blot and immunostaining. Patterns of RNA and protein expression of GLUT1-3 in both species agree closely with published reports from other birds and mammals. As in other birds, and unlike in mammals, we did not detect GLUT4. A lack of GLUT4 correlates with hyperglycemia and an uncoupling of exercise intensity and relative oxidation of carbohydrates in hummingbirds. The function of GLUTs present in hummingbird muscle tissue (e.g. GLUT1 and 3 remain undescribed. Thus, further work is necessary to determine if high capillary density, and thus surface area across which cellular-mediated transport of sugars into active tissues (e.g. muscle occurs, rather than taxon-specific differences in GLUT density or kinetics, can account for observed rapid rates of sugar flux into these

Gluts and battles: Canadian pipeline growth fear coming to U.S. markets

International Nuclear Information System (INIS)

Jaremko, G.

1997-01-01

Industry peers in the U.S.A. sounded a warning to Canadian natural gas exporters and pipeline owners about an approaching 'capacity glut' if they stay on their current aggressive expansion course. Just one of the current crop of export pipeline projects would be enough to bring on a 'displacement scenario' where delivery capacity overtakes demand and pits Canadian and American suppliers against one another for markets. These warnings were contained in a recent report by the Interstate Natural Gas Association of America. According to this report, today's pipeline projects lineup faces the American industry with the possibility of confronting a 70 per cent jump in Canadian exports to 4.9 trillion cubic feet per year by 2005, equal to 175 per cent of anticipated growth in demand. The report stresses the importance of responsible expansion of capacity based on realistic rise in demand estimates. The ball is in the industry's court to regulate itself since regulators no longer try to manage supply and demand

d-Fructose Modification Enhanced Internalization of Mixed Micelles in Breast Cancer Cells via GLUT5 Transporters.

Science.gov (United States)

Zhou, Xu; Qin, Xianyan; Gong, Tao; Zhang, Zhi-Rong; Fu, Yao

2017-07-01

d-Fructose modified poly(ε-caprolactone)-polyethylene glycol (PCL-PEG-Fru) diblock amphiphile is synthesized via Cu(I)-catalyzed click chemistry, which self-assembles with D-α-tocopheryl polyethylene glycol 1000 succinate (TPGS) into PCL-PEG-Fru/TPGS mixed micelles (PPF MM). It has been proven that glucose transporter (GLUT)5 is overexpressed in MCF-7 cells other than L929 cells. In this study, PPF MM exhibit a significantly higher uptake efficiency than fructose-free PCL-PEG-N 3 /TPGS mixed micelles in both 2D MCF-7 cells and 3D tumor spheroids. Also, the presence of free d-fructose competitively inhibits the internalization of PPF MM in MCF-7 cells other than L929 cells. PPF MM show selective tumor accumulation in MCF-7 breast tumor bearing mice xenografts. Taken together, PPF MM represent a promising nanoscale carrier system to achieve GLUT5-mediated cell specific delivery in cancer therapy. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Genetic variation of the GLUT10 glucose transporter (SLC2A10) and relationships to type 2 diabetes and intermediary traits

DEFF Research Database (Denmark)

Andersen, Gitte; Rose, Christian Schack; Hamid, Yasmin Hassan

2003-01-01

The SLC2A10 gene encodes the GLUT10 facilitative glucose transporter, which is expressed in high amounts in liver and pancreas. The gene is mapped to chromosome 20q12-q13.1, a region that has been shown to be linked to type 2 diabetes. The gene was examined in 61 Danish type 2 diabetic patients......, and a total of six variants (-27C-->T, Ala206Thr, Ala272Ala, IVS2 + 10G-->A, IVS4 + 18T-->G, and IVS4 + 26G-->A) were identified and investigated in an association study, which included 503 type 2 diabetic patients and 510 glucose-tolerant control subjects. None of the variants were associated with type 2...... substantially to the pathogenesis of type 2 diabetes in the examined study population. However, the codon 206 polymorphism may be related to the interindividual variation in fasting and oral glucose-induced serum insulin levels....

Assessment of metabolic and mitochondrial dynamics in CD4+ and CD8+ T cells in virologically suppressed HIV-positive individuals on combination antiretroviral therapy.

Directory of Open Access Journals (Sweden)

Jesse J R Masson

Full Text Available Metabolism plays a fundamental role in supporting the growth, proliferation and effector functions of T cells. We investigated the impact of HIV infection on key processes that regulate glucose uptake and mitochondrial biogenesis in subpopulations of CD4+ and CD8+ T cells from 18 virologically-suppressed HIV-positive individuals on combination antiretroviral therapy (cART; median CD4+ cell count: 728 cells/μl and 13 HIV seronegative controls. Mitochondrial membrane potential (MMP and reactive oxygen species (ROS production were also analysed in total CD4+ and CD8+ T cells. Among HIV+/cART individuals, expression of glucose transporter (Glut1 and mitochondrial density were highest within central memory and naïve CD4+ T cells, and lowest among effector memory and transitional memory T cells, with similar trends in HIV-negative controls. Compared to HIV-negative controls, there was a trend towards higher percentage of circulating CD4+Glut1+ T cells in HIV+/cART participants. There were no significant differences in mitochondrial dynamics between subject groups. Glut1 expression was positively correlated with mitochondrial density and MMP in total CD4+ T cells, while MMP was also positively correlated with ROS production in both CD4+ and CD8+ T cells. Our study characterizes specific metabolic features of CD4+ and CD8+ T cells in HIV-negative and HIV+/cART individuals and will invite future studies to explore the immunometabolic consequences of HIV infection.

Human adenovirus Ad36 and its E4orf1 gene enhance cellular glucose uptake even in the presence of inflammatory cytokines.

Science.gov (United States)

Na, Ha-Na; Dubuisson, Olga; Hegde, Vijay; Nam, Jae-Hwan; Dhurandhar, Nikhil V

2016-05-01

Aging and obesity are associated with elevated pro-inflammatory cytokines such as monocyte chemoattractant protein (MCP)-1 and tumor necrosis factor (TNF)α, which are linked to insulin resistance. Anti-inflammatory agents have marginal effect in improving insulin resistance. Hence, agents are needed to improve glycemic control despite the inflammation. Ad36, a human adenovirus, increases TNFα and MCP1 mRNA in adipose tissue, yet improves glycemic control in mice. Ad36 via its E4orf1 gene, up-regulates AKT/glucose transporter (Glut)-4 signaling to enhance cellular glucose uptake. Directly test a role of Ad36, or E4orf1 in enhancing cellular glucose uptake in presence of inflammatory cytokines. Experiment 1: 3T3-L1 preadipocytes were treated with 0, 10 or 100 ng/mL lipopolysaccharides (LPS), and infected with 0 or 5 plaque forming units (PFU) of Ad36/cell. 3T3-L1 cells that stably and inducibly express E4orf1 or a null vector (pTRE-E4orf1 or pTRE-null cells), were similarly treated with LPS and then with doxycycline, to induce E4orf1. Experiment 2: 3T3L1 preadipocytes were treated with 25 nM MCP1 or 20 nM TNFα for 16 h, followed by infection with 0 or 5 PFU of Ad36/cell. Experiment 3: pTRE-E4orf1 or -null cells were similarly treated with MCP1 or TNFα followed by doxycycline to induce E4orf1. Cellular glucose uptake and cellular signaling were determined 72 h post-Ad36 infection or E4orf1-induction, in continued presence of MCP1 or TNFα. In 3T3-L1 preadipocytes, Ad36, but not E4orf1, increased MCP1 and TNFα mRNA, in presence of LPS stimulation. Ad36 or E4orf1 up-regulated AKT-phosphorylation and Glut4 and increased glucose uptake (P E4orf1 does not appear to stimulate inflammatory response. Ad36 and E4orf1 both enhance cellular glucose uptake even in presence of inflammation. Further research is needed to harness this novel and beneficial property of E4orf1 to improve hyperglycemia despite chronic inflammation that is commonly present in aging and

Regulation of glucose transporter protein-1 and vascular endothelial growth factor by hypoxia inducible factor 1α under hypoxic conditions in Hep-2 human cells.

Science.gov (United States)

Xu, Ou; Li, Xiaoming; Qu, Yongtao; Liu, Shuang; An, Jie; Wang, Maoxin; Sun, Qingjia; Zhang, Wen; Lu, Xiuying; Pi, Lihong; Zhang, Min; Shen, Yupeng

2012-12-01

The present study evaluated the regulation of glucose transporter protein-1 (Glut-1) and vascular endothelial growth factor (VEGF) by hypoxia inducible factor 1α (HIF-1α) under hypoxic conditions in Hep-2 human cells to explore the feasibility of these three genes as tumor markers. Hep-2 cells were cultured under hypoxic and normoxic conditions for 6, 12, 24, 36 and 48 h. The proliferation of Hep-2 cells was evaluated using an MTT assay. The protein and mRNA expression levels of HIF-1α, Glut-1 and VEGF were detected using the S-P immunocytochemical method, western blotting and reverse transcription polymerase chain reaction (RT-PCR). The results revealed that the expression levels of HIF-1α, Glut-1 and VEGF protein in Hep-2 cells were significantly elevated under hypoxic conditions compared with those under normoxic conditions over 36 h. Under hypoxic conditions, mRNA levels of HIF-1α were stable, while mRNA levels of Glut-1 and VEGF changed over time. In conclusion, Glut-1 and VEGF were upregulated by HIF-1α under hypoxic conditions in a time-dependent manner in Hep-2 cells and their co-expression serves as a tumor marker.

Molecular cloning and characterization of glucose transporter 1 ...

African Journals Online (AJOL)

Glucose transporter type-1 (glut1) and citrate synthase plays crucial role in glucose transport and regulation of tricarboxylic acid cycle (TCA) cycle in mammalian energy metabolism. The present study was aimed to clone and characterize glut1 and citrate synthase cDNA in water buffalo (Bubalus bubalis). Total of 90 ...

Rac1 is a novel regulator of contraction-stimulated glucose uptake in skeletal muscle

DEFF Research Database (Denmark)

Sylow, Lykke; Jensen, Thomas Elbenhardt; Kleinert, Maximilian

2013-01-01

In skeletal muscle, the actin cytoskeleton-regulating GTPase, Rac1, is necessary for insulin-dependent GLUT4 translocation. Muscle contraction increases glucose transport and represents an alternative signaling pathway to insulin. Whether Rac1 is activated by muscle contraction and regulates...

Ezrin is down-regulated in diabetic kidney glomeruli and regulates actin reorganization and glucose uptake via GLUT1 in cultured podocytes.

Science.gov (United States)

Wasik, Anita A; Koskelainen, Susanna; Hyvönen, Mervi E; Musante, Luca; Lehtonen, Eero; Koskenniemi, Kerttu; Tienari, Jukka; Vaheri, Antti; Kerjaschki, Dontscho; Szalay, Csaba; Révész, Csaba; Varmanen, Pekka; Nyman, Tuula A; Hamar, Peter; Holthöfer, Harry; Lehtonen, Sanna

2014-06-01

Diabetic nephropathy is a complication of diabetes and a major cause of end-stage renal disease. To characterize the early pathophysiological mechanisms leading to glomerular podocyte injury in diabetic nephropathy, we performed quantitative proteomic profiling of glomeruli isolated from rats with streptozotocin-induced diabetes and controls. Fluorescence-based two-dimensional difference gel electrophoresis, coupled with mass spectrometry, identified 29 differentially expressed spots, including actin-binding protein ezrin and its interaction partner, NHERF2, which were down-regulated in the streptozotocin group. Knockdown of ezrin by siRNA in cultured podocytes increased glucose uptake compared with control siRNA-transfected cells, apparently by increasing translocation of glucose transporter GLUT1 to the plasma membrane. Knockdown of ezrin also induced actin remodeling under basal conditions, but reduced insulin-stimulated actin reorganization. Ezrin-dependent actin remodeling involved cofilin-1 that is essential for the turnover and reorganization of actin filaments. Phosphorylated, inactive cofilin-1 was up-regulated in diabetic glomeruli, suggesting altered actin dynamics. Furthermore, IHC analysis revealed reduced expression of ezrin in the podocytes of patients with diabetes. Our findings suggest that ezrin may play a role in the development of the renal complication in diabetes by regulating transport of glucose and organization of the actin cytoskeleton in podocytes. Copyright © 2014 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.

Adipose tissue insulin receptor and glucose transporter 4 expression, and blood glucose and insulin responses during glucose tolerance tests in transition Holstein cows with different body condition.

Science.gov (United States)

Jaakson, H; Karis, P; Ling, K; Ilves-Luht, A; Samarütel, J; Henno, M; Jõudu, I; Waldmann, A; Reimann, E; Pärn, P; Bruckmaier, R M; Gross, J J; Kaart, T; Kass, M; Ots, M

2018-01-01

Glucose uptake in tissues is mediated by insulin receptor (INSR) and glucose transporter 4 (GLUT4). The aim of this study was to examine the effect of body condition during the dry period on adipose tissue mRNA and protein expression of INSR and GLUT4, and on the dynamics of glucose and insulin following the i.v. glucose tolerance test in Holstein cows 21 d before (d -21) and after (d 21) calving. Cows were grouped as body condition score (BCS) ≤3.0 (thin, T; n = 14), BCS = 3.25 to 3.5 (optimal, O; n = 14), and BCS ≥3.75 (overconditioned, OC; n = 14). Blood was analyzed for glucose, insulin, fatty acids, and β-hydroxybutyrate concentrations. Adipose tissue was analyzed for INSR and GLUT4 mRNA and protein concentrations. During the glucose tolerance test 0.15 g/kg of body weight glucose was infused; blood was collected at -5, 5, 10, 20, 30, 40, 50, and 60 min, and analyzed for glucose and insulin. On d -21 the area under the curve (AUC) of glucose was smallest in group T (1,512 ± 33.9 mg/dL × min) and largest in group OC (1,783 ± 33.9 mg/dL × min), and different between all groups. Basal insulin on d -21 was lowest in group T (13.9 ± 2.32 µU/mL), which was different from group OC (24.9 ± 2.32 µU/mL. On d -21 the smallest AUC 5-60 of insulin in group T (5,308 ± 1,214 µU/mL × min) differed from the largest AUC in group OC (10,867 ± 1,215 µU/mL × min). Time to reach basal concentration of insulin in group OC (113 ± 14.1 min) was longer compared with group T (45 ± 14.1). The INSR mRNA abundance on d 21 was higher compared with d -21 in groups T (d -21: 3.3 ± 0.44; d 21: 5.9 ± 0.44) and O (d -21: 3.7 ± 0.45; d 21: 4.7 ± 0.45). The extent of INSR protein expression on d -21 was highest in group T (7.3 ± 0.74 ng/mL), differing from group O (4.6 ± 0.73 ng/mL), which had the lowest expression. The amount of GLUT4 protein on d -21 was lowest in group OC (1.2 ± 0.14 ng/mL), different from group O (1.8 ± 0.14 ng/mL), which had the highest amount

The Monocarboxylate Transporter Inhibitor α-Cyano-4-Hydroxycinnamic Acid Disrupts Rat Lung Branching

Directory of Open Access Journals (Sweden)

Sara Granja

2013-12-01

Full Text Available Background/Aims: The human embryo develops in a hypoxic environment. In this way, cells have to rely on the glycolytic pathway for energy supply, leading to an intracellular accumulation of monocarboxylates such as lactate and pyruvate. These acids have an important role in cell metabolism and their rapid transport across the plasma membrane is crucial for the maintenance of intracellular pH homeostasis. This transport is mediated by a family of transporters, designated by monocarboxylate transporters (MCTs, namely isoforms 1 and 4. MCT1/4 expression is regulated by the ancillary protein CD147.The general aim of this study was to characterize the expression pattern of MCT1/4, CD147 and the glucose transporter GLUT1 during human fetal lung development and elucidate the role of MCTs in lung development. Methods: The expression pattern of MCT1/4 and GLUT1 was characterized by immunohistochemistry and fetal lung viability and branching were evaluated by exposing rat fetal lung explants to CHC, an inhibitor of MCT activity. Results: Our findings show that all the biomarkers are differently expressed during fetal lung development and that CHC appears to have an inhibitory effect on lung branching and viability, in a dose dependent way. Conclusion: We provide evidence for the role of MCTs in embryo lung development, however to prove the dependence of MCT activity further studies are waranted.

Enigma interacts with adaptor protein with PH and SH2 domains to control insulin-induced actin cytoskeleton remodeling and glucose transporter 4 translocation

DEFF Research Database (Denmark)

Barres, Romain; Grémeaux, Thierry; Gual, Philippe

2006-01-01

a critical role in actin cytoskeleton organization in fibroblastic cells. Because actin rearrangement is important for insulin-induced glucose transporter 4 (Glut 4) translocation, we studied the potential involvement of Enigma in insulin-induced glucose transport in 3T3-L1 adipocytes. Enigma m...

Dipalmitoleoylphosphoethanolamine as a PP2A enhancer obstructs insulin signaling by promoting Ser/Thr dephosphorylation of Akt.

Science.gov (United States)

Tsuchiya, Ayako; Kanno, Takeshi; Nishizaki, Tomoyuki

2014-01-01

The phospholipid phosphatidylethanolamine is implicated in the regulation of a variety of cellular processes. The present study investigated the effect of phosphatidylethanolamines such as 1,2-diarachidonoyl-sn-glycero-3-phosphoethanolamine (DAPE), 1,2-dilinoleoyl-sn-glycero-3-phosphoethanolamine (DLPE), 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE), and 1,2-dipalmitoleoyl-sn-glycero-3-phosphoethanolamine (DPPE) on protein phosphatases, Akt1/2 activity, GLUT4 mobilizations, and glucose uptake into cells. Activity of protein phosphatase 2A (PP2A) was assayed under the cell-free conditions, and Western blotting, intracellular GLUT4 trafficking, and glucose uptake into cells were monitored using differentiated 3T3-L1-GLUT4myc adipocytes. Of the investigated phosphatidylethanolamines, DLPE and DPPE significantly enhanced PP2A activity. DPPE inhibited insulin-induced phosphorylation of Akt1/2 at Thr308/309 and Ser473/474 in differentiated 3T3-L1-GLUT4myc adipocytes. DPPE also inhibited insulin-stimulated GLUT4 translocation to the cell surface and reduced insulin-stimulated glucose uptake into adipocytes. The results of the present study indicate that the PP2A enhancer DPPE obstructs insulin signaling by promoting serine/threonine dephosphorylation of Akt1/2, resulting in the suppression of GLUT4 translocation to the cell surface and glucose uptake into adipocytes. © 2014 S. Karger AG, Basel.

Dipalmitoleoylphosphoethanolamine as a PP2A Enhancer Obstructs Insulin Signaling by Promoting Ser/Thr Dephosphorylation of Akt

Directory of Open Access Journals (Sweden)

Ayako Tsuchiya

2014-08-01

Full Text Available Background/Aims: The phospholipid phosphatidylethanolamine is implicated in the regulation of a variety of cellular processes. The present study investigated the effect of phosphatidylethanolamines such as 1,2-diarachidonoyl-sn-glycero-3-phosphoethanolamine (DAPE, 1,2-dilinoleoyl-sn-glycero-3-phosphoethanolamine (DLPE, 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE, and 1,2-dipalmitoleoyl-sn-glycero-3-phosphoethanolamine (DPPE on protein phosphatases, Akt1/2 activity, GLUT4 mobilizations, and glucose uptake into cells. Methods: Activity of protein phosphatase 2A (PP2A was assayed under the cell-free conditions, and Western blotting, intracellular GLUT4 trafficking, and glucose uptake into cells were monitored using differentiated 3T3-L1-GLUT4myc adipocytes. Results: Of the investigated phosphatidylethanolamines, DLPE and DPPE significantly enhanced PP2A activity. DPPE inhibited insulin-induced phosphorylation of Akt1/2 at Thr308/309 and Ser473/474 in differentiated 3T3-L1-GLUT4myc adipocytes. DPPE also inhibited insulin-stimulated GLUT4 translocation to the cell surface and reduced insulin-stimulated glucose uptake into adipocytes. Conclusion: The results of the present study indicate that the PP2A enhancer DPPE obstructs insulin signaling by promoting serine/threonine dephosphorylation of Akt1/2, resulting in the suppression of GLUT4 translocation to the cell surface and glucose uptake into adipocytes.

Enigma interacts with adaptor protein with PH and SH2 domains to control insulin-induced actin cytoskeleton remodeling and glucose transporter 4 translocation.

Science.gov (United States)

Barrès, Romain; Grémeaux, Thierry; Gual, Philippe; Gonzalez, Teresa; Gugenheim, Jean; Tran, Albert; Le Marchand-Brustel, Yannick; Tanti, Jean-François

2006-11-01

APS (adaptor protein with PH and SH2 domains) initiates a phosphatidylinositol 3-kinase-independent pathway involved in insulin-stimulated glucose transport. We recently identified Enigma, a PDZ and LIM domain-containing protein, as a partner of APS and showed that APS-Enigma complex plays a critical role in actin cytoskeleton organization in fibroblastic cells. Because actin rearrangement is important for insulin-induced glucose transporter 4 (Glut 4) translocation, we studied the potential involvement of Enigma in insulin-induced glucose transport in 3T3-L1 adipocytes. Enigma mRNA was expressed in differentiated adipocytes and APS and Enigma were colocalized with cortical actin. Expression of an APS mutant unable to bind Enigma increased the insulin-induced Glut 4 translocation to the plasma membrane. By contrast, overexpression of Enigma inhibited insulin-stimulated glucose transport and Glut 4 translocation without alterations in proximal insulin signaling. This inhibitory effect was prevented with the deletion of the LIM domains of Enigma. Using time-lapse fluorescent microscopy of green fluorescent protein-actin, we demonstrated that the overexpression of Enigma altered insulin-induced actin rearrangements, whereas the expression of Enigma without its LIM domains was without effect. A physiological link between increased expression of Enigma and an alteration in insulin-induced glucose uptake was suggested by the increase in Enigma mRNA expression in adipose tissue of diabetic obese patients. Taken together, these data strongly suggest that the interaction between APS and Enigma is involved in insulin-induced Glut 4 translocation by regulating cortical actin remodeling and raise the possibility that modification of APS/Enigma ratio could participate in the alteration of insulin-induced glucose uptake in adipose tissue.

Complex analysis of urate transporters SLC2A9, SLC22A12 and functional characterization of non-synonymous allelic variants of GLUT9 in the Czech population: no evidence of effect on hyperuricemia and gout.

Science.gov (United States)

Hurba, Olha; Mancikova, Andrea; Krylov, Vladimir; Pavlikova, Marketa; Pavelka, Karel; Stibůrková, Blanka

2014-01-01

Using European descent Czech populations, we performed a study of SLC2A9 and SLC22A12 genes previously identified as being associated with serum uric acid concentrations and gout. This is the first study of the impact of non-synonymous allelic variants on the function of GLUT9 except for patients suffering from renal hypouricemia type 2. The cohort consisted of 250 individuals (150 controls, 54 nonspecific hyperuricemics and 46 primary gout and/or hyperuricemia subjects). We analyzed 13 exons of SLC2A9 (GLUT9 variant 1 and GLUT9 variant 2) and 10 exons of SLC22A12 by PCR amplification and sequenced directly. Allelic variants were prepared and their urate uptake and subcellular localization were studied by Xenopus oocytes expression system. The functional studies were analyzed using the non-parametric Wilcoxon and Kruskall-Wallis tests; the association study used the Fisher exact test and linear regression approach. We identified a total of 52 sequence variants (12 unpublished). Eight non-synonymous allelic variants were found only in SLC2A9: rs6820230, rs2276961, rs144196049, rs112404957, rs73225891, rs16890979, rs3733591 and rs2280205. None of these variants showed any significant difference in the expression of GLUT9 and in urate transport. In the association study, eight variants showed a possible association with hyperuricemia. However, seven of these were in introns and the one exon located variant, rs7932775, did not show a statistically significant association with serum uric acid concentration. Our results did not confirm any effect of SLC22A12 and SLC2A9 variants on serum uric acid concentration. Our complex approach using association analysis together with functional and immunohistochemical characterization of non-synonymous allelic variants did not show any influence on expression, subcellular localization and urate uptake of GLUT9.

What is Driving Global Imbalances? The Global Savings Glut Hypothesis Reexamined

Directory of Open Access Journals (Sweden)

Jai-Won Ryou

2009-12-01

Full Text Available In the middle of the global financial crisis, global imbalances seem to have been resolved to some extent, but it remains to be seen whether these imbalances will emerge again along with economic recovery. In order to cope with this global issue, we need to clarify what caused global imbalances in the first place. This paper aims to evaluate the relative importance of the "global savings glut" to the U.S. external imbalances. Drawing on the portfolio balance model, we analyze how the process of interaction between the U.S. current account deficit, capital inflows, and the U.S. dollar exchange rate is linked to domestic and external factors. Our empirical analysis shows that the U.S. current account deficit maintained since the early 1990s is mainly driven by the domestic factors, such as a decrease in the U.S. national savings and an increase in money supply growth. The size of the negative effect of a "global savings glut" measured by an increase in the East Asian countries' national savings (i.e. China, Japan and Korea on the U.S. current account seems to be exaggerated. Meanwhile, current account does not appear to be sensitive to changes in the exchange rate. This finding implies that the rectification of global imbalances is hardly possible to achieve by means of depreciating the U.S. dollar alone while leaving the structural factors unchanged. In order to achieve global rebalancing, the U.S. should increase its savings rate, reduce fiscal deficit, and tighten its money supply. While an increase in the domestic demand in the surplus countries such as China and Japan may be helpful in rectifying global imbalances, it appears to be insufficient per se.

Identification of novel targets for PGC-1α and histone deacetylase inhibitors in neuroblastoma cells

International Nuclear Information System (INIS)

Cowell, Rita M.; Talati, Pratik; Blake, Kathryn R.; Meador-Woodruff, James H.; Russell, James W.

2009-01-01

Recent evidence suggests that the transcriptional coactivator peroxisome proliferator activated receptor γ coactivator 1α (PGC-1α) is involved in the pathology of Huntington's Disease (HD). While animals lacking PGC-1α express lower levels of genes involved in antioxidant defense and oxidative phosphorylation in the brain, little is known about other targets for PGC-1α in neuronal cells and whether there are ways to pharmacologically target PGC-1α in neurons. Here, PGC-1α overexpression in SH-SY5Y neuroblastoma cells upregulated expression of genes involved in mitochondrial function, glucose transport, fatty acid metabolism, and synaptic function. Overexpression also decreased vulnerability to hydrogen peroxide-induced cell death and caspase 3 activation. Treatment of cells with the histone deacetylase inhibitors (HDACi's) trichostatin A and valproic acid upregulated PGC-1α and glucose transporter 4 (GLUT4). These results suggest that PGC-1α regulates multiple pathways in neurons and that HDACi's may be good candidates to target PGC-1α and GLUT4 in HD and other neurological disorders.

Microsatellite alterations in head and neck squamous cell carcinoma and relation to expression of pimonidazole, CA IX and GLUT-1

International Nuclear Information System (INIS)

Schutter, Harlinde de; Barbe, Barbara; Spaepen, Marijke

2006-01-01

Background and Purpose: Because the locoregional control for HNSCC is still disappointing, research efforts focus on the exploration of new molecular markers located in both tumour and microenvironment, which could help stratify patients. The aim of the present work was therefore first to assess microsatellite alterations and hypoxia in HNSCC as possible molecular markers. Second, a relation between both was investigated, as hypoxia is known to select for genetic alterations. Material and methods: Forty-eight patients with advanced HNSCC treated by surgery ± radiotherapy were included. MSI and LOH were investigated with microsatellite markers using automatic fragment analysis. The presence of hypoxia was assessed by immunohistochemistry for pimonidazole, CA IX and GLUT-1. The mutual relationship between MSI/LOH and hypoxia was evaluated. Results: No MSI was detected in this patient group. LOH occurred mostly on chromosomal arms 3p, 5q, 9p, 17p and 17q. Patients with LOH at D17S799, located in the near environment of p53, showed a higher CA IX expression (p = 0.01). Conclusions: LOH is a possible molecular marker in HNSCC. The positive correlation between LOH at D17S799 and CA IX is in full concordance with previous publications linking hypoxia to selective pressure on the p53 gene

Acute hyperglycemia produces transient improvement in glucose transporter type 1 deficiency.

Science.gov (United States)

Akman, Cigdem I; Engelstad, Kristin; Hinton, Veronica J; Ullner, Paivi; Koenigsberger, Dorcas; Leary, Linda; Wang, Dong; De Vivo, Darryl C

2010-01-01

Glucose transporter type 1 deficiency syndrome (Glut1-DS) is characterized clinically by acquired microcephaly, infantile-onset seizures, psychomotor retardation, choreoathetosis, dystonia, and ataxia. The laboratory signature is hypoglycorrhachia. The 5-hour oral glucose tolerance test (OGTT) was performed to assess cerebral function and systemic carbohydrate homeostasis during acute hyperglycemia, in the knowledge that GLUT1 is constitutively expressed ubiquitously and upregulated in the brain. Thirteen Glut1-DS patients completed a 5-hour OGTT. Six patients had prolonged electroencephalographic (EEG)/video monitoring, 10 patients had plasma glucose and serum insulin measurements, and 5 patients had repeated measures of attention, memory, fine motor coordination, and well-being. All patients had a full neuropsychological battery prior to OGTT. The glycemic profile and insulin response during the OGTT were normal. Following the glucose load, transient improvement of clinical seizures and EEG findings were observed, with the most significant improvement beginning within the first 30 minutes and continuing for 180 minutes. Thereafter, clinical seizures returned, and EEG findings worsened. Additionally, transient improvement in attention, fine motor coordination, and reported well-being were observed without any change in memory performance. This study documents transient neurological improvement in Glut1-DS patients following acute hyperglycemia, associated with improved fine motor coordination and attention. Also, systemic carbohydrate homeostasis was normal, despite GLUT1 haploinsufficiency, confirming the specific role of GLUT1 as the transporter of metabolic fuel across the blood-brain barrier. The transient improvement in brain function underscores the rate-limiting role of glucose transport and the critical minute-to-minute dependence of cerebral function on fuel availability for energy metabolism.

Role of vitamin D on the expression of glucose transporters in L6 myotubes

Directory of Open Access Journals (Sweden)

Bubblu Tamilselvan

2013-01-01

Full Text Available Altered expression of glucose transporters is a major characteristic of diabetes. Vitamin D has evolved widespread interest in the pathogenesis and prevention of diabetes. The present study was designed to investigate the effect of vitamin D in the overall regulation of muscle cell glucose transporter expression. L6 cells were exposed to type 1 and type 2 diabetic conditions and the effect of calcitriol (1,25, dihydroxy cholicalciferol on the expression of glucose transporters was studied by real time polymerase chain reaction (RT-PCR. There was a significant decrease in glucose transporter type 1 (GLUT1, GLUT4, vitamin D receptor (VDR, and IR expression in type 1 and 2 diabetic model compared to control group. Treatment of myoblasts with 10-7 M calcitriol for 24 h showed a significant increase in GLUT1, GLUT4, VDR, and insulin receptor (IR expression. The results indicate a potential antidiabetic function of vitamin D on GLUT1, GLUT4, VDR, and IR by improving receptor gene expression suggesting a role for vitamin D in regulation of expression of the glucose transporters in muscle cells.

A common Greenlandic TBC1D4 variant confers muscle insulin resistance and type 2 diabetes

DEFF Research Database (Denmark)

Moltke, Ida; Grarup, Niels; Jørgensen, Marit Eika

2014-01-01

carriers of this variant have markedly higher concentrations of plasma glucose (β = 3.8 mmol l(-1), P = 2.5 × 10(-35)) and serum insulin (β = 165 pmol l(-1), P = 1.5 × 10(-20)) 2 hours after an oral glucose load compared with individuals with other genotypes (both non-carriers and heterozygous carriers......). Furthermore, homozygous carriers have marginally lower concentrations of fasting plasma glucose (β = -0.18 mmol l(-1), P = 1.1 × 10(-6)) and fasting serum insulin (β = -8.3 pmol l(-1), P = 0.0014), and their T2D risk is markedly increased (odds ratio (OR) = 10.3, P = 1.6 × 10(-24)). Heterozygous carriers have...... transporter GLUT4, with increasing number of p.Arg684Ter alleles. These findings are concomitant with a severely decreased insulin-stimulated glucose uptake in muscle, leading to postprandial hyperglycaemia, impaired glucose tolerance and T2D. The observed effect sizes are several times larger than any...

Conventional kinesin KIF5B mediates adiponectin secretion in 3T3-L1 adipocytes

Energy Technology Data Exchange (ETDEWEB)

Cui, Ju, E-mail: juzi.cui@gmail.com [The Key Laboratory of Geriatrics, Beijing Hospital and Beijing Institute of Geriatrics, Beijing (China); Pang, Jing; Lin, Ya-Jun; Jiang, Ping; Gong, Huan [The Key Laboratory of Geriatrics, Beijing Hospital and Beijing Institute of Geriatrics, Beijing (China); Wang, Zai [Institute of Clinical Medical Sciences, China-Japan Friendship Hospital, Beijing (China); Li, Jian; Cai, Jian-Ping [The Key Laboratory of Geriatrics, Beijing Hospital and Beijing Institute of Geriatrics, Beijing (China); Huang, Jian-Dong, E-mail: jdhuang@hku.hk [School of Biomedical Sciences and Shenzhen Institute of Research and Innovation, The University of Hong Kong, Pokfulam (Hong Kong); The Centre for Synthetic Biology Engineering Research, Shenzhen Institutes of Advanced Technology, Shenzhen (China); Zhang, Tie-Mei, E-mail: tmzhang126@126.com [The Key Laboratory of Geriatrics, Beijing Hospital and Beijing Institute of Geriatrics, Beijing (China)

2016-08-05

Insulin stimulates adiponectin secretion and glucose transporter type 4 (GLUT4) translocation in adipocyte to regulate metabolism homeostasis. Similar to GLUT4 translocation, intracellular trafficking and release of adiponectin in adipocytes relies on the trans-Golgi network and endosomal system. Recent studies show that the heavy chain of conventional kinesin (KIF5B) mediates GLUT4 translocation in murine 3T3-L1 adipocytes, however, the motor machinery involved in mediating intracellular trafficking and release of adiponectin is unknown. Here, we examined the role of KIF5B in the regulation of adiponectin secretion. The KIF5B level was up-regulated during 3T3-L1 adipogenesis. This increase in cytosolic KIF5B was synchronized with the induction of adiponectin. Endogenous KIF5B and adiponectin were partially colocalized at the peri-nuclear and cytosolic regions. In addition, adiponectin-containing vesicles were co-immunoprecipitated with KIF5B. Knockdown of KIF5B resulted in a marked inhibition of adiponectin secretion and overexpression of KIF5B enhanced adiponectin release, whereas leptin secretion was not affected by changes in KIF5B expression. These data suggest that the secretion of adiponectin, but not leptin, is dependent on functional KIF5B. - Highlights: • The KIF5B level was up regulated during 3T3-L1 adipogenesis. • Endogenous KIF5B and adiponectin were partially colicalized. • Adiponectin-containing vesicles were co-immunoprecipitated with KIF5B. • The secretion of adiponectin, but not leptin, is dependent on functional KIF5B.

Conventional kinesin KIF5B mediates adiponectin secretion in 3T3-L1 adipocytes

International Nuclear Information System (INIS)

Cui, Ju; Pang, Jing; Lin, Ya-Jun; Jiang, Ping; Gong, Huan; Wang, Zai; Li, Jian; Cai, Jian-Ping; Huang, Jian-Dong; Zhang, Tie-Mei

2016-01-01

Insulin stimulates adiponectin secretion and glucose transporter type 4 (GLUT4) translocation in adipocyte to regulate metabolism homeostasis. Similar to GLUT4 translocation, intracellular trafficking and release of adiponectin in adipocytes relies on the trans-Golgi network and endosomal system. Recent studies show that the heavy chain of conventional kinesin (KIF5B) mediates GLUT4 translocation in murine 3T3-L1 adipocytes, however, the motor machinery involved in mediating intracellular trafficking and release of adiponectin is unknown. Here, we examined the role of KIF5B in the regulation of adiponectin secretion. The KIF5B level was up-regulated during 3T3-L1 adipogenesis. This increase in cytosolic KIF5B was synchronized with the induction of adiponectin. Endogenous KIF5B and adiponectin were partially colocalized at the peri-nuclear and cytosolic regions. In addition, adiponectin-containing vesicles were co-immunoprecipitated with KIF5B. Knockdown of KIF5B resulted in a marked inhibition of adiponectin secretion and overexpression of KIF5B enhanced adiponectin release, whereas leptin secretion was not affected by changes in KIF5B expression. These data suggest that the secretion of adiponectin, but not leptin, is dependent on functional KIF5B. - Highlights: • The KIF5B level was up regulated during 3T3-L1 adipogenesis. • Endogenous KIF5B and adiponectin were partially colicalized. • Adiponectin-containing vesicles were co-immunoprecipitated with KIF5B. • The secretion of adiponectin, but not leptin, is dependent on functional KIF5B.

Complex analysis of urate transporters SLC2A9, SLC22A12 and functional characterization of non-synonymous allelic variants of GLUT9 in the Czech population: no evidence of effect on hyperuricemia and gout.

Directory of Open Access Journals (Sweden)

Olha Hurba

Full Text Available OBJECTIVE: Using European descent Czech populations, we performed a study of SLC2A9 and SLC22A12 genes previously identified as being associated with serum uric acid concentrations and gout. This is the first study of the impact of non-synonymous allelic variants on the function of GLUT9 except for patients suffering from renal hypouricemia type 2. METHODS: The cohort consisted of 250 individuals (150 controls, 54 nonspecific hyperuricemics and 46 primary gout and/or hyperuricemia subjects. We analyzed 13 exons of SLC2A9 (GLUT9 variant 1 and GLUT9 variant 2 and 10 exons of SLC22A12 by PCR amplification and sequenced directly. Allelic variants were prepared and their urate uptake and subcellular localization were studied by Xenopus oocytes expression system. The functional studies were analyzed using the non-parametric Wilcoxon and Kruskall-Wallis tests; the association study used the Fisher exact test and linear regression approach. RESULTS: We identified a total of 52 sequence variants (12 unpublished. Eight non-synonymous allelic variants were found only in SLC2A9: rs6820230, rs2276961, rs144196049, rs112404957, rs73225891, rs16890979, rs3733591 and rs2280205. None of these variants showed any significant difference in the expression of GLUT9 and in urate transport. In the association study, eight variants showed a possible association with hyperuricemia. However, seven of these were in introns and the one exon located variant, rs7932775, did not show a statistically significant association with serum uric acid concentration. CONCLUSION: Our results did not confirm any effect of SLC22A12 and SLC2A9 variants on serum uric acid concentration. Our complex approach using association analysis together with functional and immunohistochemical characterization of non-synonymous allelic variants did not show any influence on expression, subcellular localization and urate uptake of GLUT9.

Weekly intra-amniotic IGF-1 treatment increases growth of growth-restricted ovine fetuses and up-regulates placental amino acid transporters.

Directory of Open Access Journals (Sweden)

Jibran A Wali

Full Text Available Frequent treatment of the growth-restricted (IUGR ovine fetus with intra-amniotic IGF-1 increases fetal growth. We aimed to determine whether increased growth was maintained with an extended dosing interval and to examine possible mechanisms. Pregnant ewes were allocated to three groups: Control, and two IUGR groups (induced by placental embolization treated with weekly intra-amniotic injections of either saline (IUGR or 360 µg IGF-1 (IGF1. IUGR fetuses were hypoxic, hyperuremic, hypoglycemic, and grew more slowly than controls. Placental glucose uptake and SLC2A1 (GLUT2 mRNA levels decreased in IUGR fetuses, but SLC2A3 (GLUT3 and SLC2A4 (GLUT4 levels were unaffected. IGF-1 treatment increased fetal growth rate, did not alter uterine blood flow or placental glucose uptake, and increased placental SLC2A1 and SLC2A4 (but not SLC2A3 mRNA levels compared with saline-treated IUGR animals. Following IGF-1 treatment, placental mRNA levels of isoforms of the system A, y(+, and L amino acid transporters increased 1.3 to 5.0 fold, while the ratio of phosphorylated-mTOR to total mTOR also tended to increase. Weekly intra-amniotic IGF-1 treatment provides a promising avenue for intra-uterine treatment of IUGR babies, and may act via increased fetal substrate supply, up-regulating placental transporters for neutral, cationic, and branched-chain amino acids, possibly via increased activation of the mTOR pathway.

The HO-1/CO system regulates mitochondrial-capillary density relationships in human skeletal muscle.

Science.gov (United States)

Pecorella, Shelly R H; Potter, Jennifer V F; Cherry, Anne D; Peacher, Dionne F; Welty-Wolf, Karen E; Moon, Richard E; Piantadosi, Claude A; Suliman, Hagir B

2015-10-15

The heme oxygenase-1 (HO-1)/carbon monoxide (CO) system induces mitochondrial biogenesis, but its biological impact in human skeletal muscle is uncertain. The enzyme system generates CO, which stimulates mitochondrial proliferation in normal muscle. Here we examined whether CO breathing can be used to produce a coordinated metabolic and vascular response in human skeletal muscle. In 19 healthy subjects, we performed vastus lateralis muscle biopsies and tested one-legged maximal O2 uptake (V̇o2max) before and after breathing air or CO (200 ppm) for 1 h daily for 5 days. In response to CO, there was robust HO-1 induction along with increased mRNA levels for nuclear-encoded mitochondrial transcription factor A (Tfam), cytochrome c, cytochrome oxidase subunit IV (COX IV), and mitochondrial-encoded COX I and NADH dehydrogenase subunit 1 (NDI). CO breathing did not increase V̇o2max (1.96 ± 0.51 pre-CO, 1.87 ± 0.50 post-CO l/min; P = not significant) but did increase muscle citrate synthase, mitochondrial density (139.0 ± 34.9 pre-CO, 219.0 ± 36.2 post-CO; no. of mitochondrial profiles/field), myoglobin content and glucose transporter (GLUT4) protein level and led to GLUT4 localization to the myocyte membrane, all consistent with expansion of the tissue O2 transport system. These responses were attended by increased cluster of differentiation 31 (CD31)-positive muscle capillaries (1.78 ± 0.16 pre-CO, 2.37 ± 0.59 post-CO; capillaries/muscle fiber), implying the enrichment of microvascular O2 reserve. The findings support that induction of the HO-1/CO system by CO not only improves muscle mitochondrial density, but regulates myoglobin content, GLUT4 localization, and capillarity in accordance with current concepts of skeletal muscle plasticity. Copyright © 2015 the American Physiological Society.

Effect of dietary fructose on portal and systemic serum fructose levels in rats and in KHK−/− and GLUT5−/− mice

Science.gov (United States)

Patel, Chirag; Sugimoto, Keiichiro; Douard, Veronique; Shah, Ami; Inui, Hiroshi; Yamanouchi, Toshikazu

2015-01-01

Elevated blood fructose concentrations constitute the basis for organ dysfunction in fructose-induced metabolic syndrome. We hypothesized that diet-induced changes in blood fructose concentrations are regulated by ketohexokinase (KHK) and the fructose transporter GLUT5. Portal and systemic fructose concentrations determined by HPLC in wild-type mice fed for 7 days 0% free fructose were fructose levels, however, increased markedly in those fed isocaloric 20% fructose, causing significant hyperglycemia. Deletion of KHK prevented fructose-induced hyperglycemia, but caused dramatic hyperfructosemia (>1 mM) with reversed portal to systemic gradients. Systemic fructose in wild-type and KHK−/− mice changed by 0.34 and 1.8 mM, respectively, for every millimolar increase in portal fructose concentration. Systemic glucose varied strongly with systemic, but not portal, fructose levels in wild-type, and was independent of systemic and portal fructose in KHK−/−, mice. With ad libitum feeding for 12 wk, fructose-induced hyperglycemia in wild-type, but not hyperfructosemia in KHK−/− mice, increased HbA1c concentrations. Increasing dietary fructose to 40% intensified the hyperfructosemia of KHK−/− and the fructose-induced hyperglycemia of wild-type mice. Fructose perfusion or feeding in rats also caused duration- and dose-dependent hyperfructosemia and hyperglycemia. Significant levels of blood fructose are maintained independent of dietary fructose, KHK, and GLUT5, probably by endogenous synthesis of fructose. KHK prevents hyperfructosemia and fructose-induced hyperglycemia that would markedly increase HbA1c levels. These findings explain the hyperfructosemia of human hereditary fructosuria as well as the hyperglycemia of fructose-induced metabolic syndrome. PMID:26316589

Selective insulin resistance in hepatocyte senescence

International Nuclear Information System (INIS)

Aravinthan, Aloysious; Challis, Benjamin; Shannon, Nicholas; Hoare, Matthew; Heaney, Judith; Alexander, Graeme J.M.

2015-01-01

Insulin resistance has been described in association with chronic liver disease for decades. Hepatocyte senescence has been demonstrated in chronic liver disease and as many as 80% of hepatocytes show a senescent phenotype in advanced liver disease. The aim of this study was to understand the role of hepatocyte senescence in the development of insulin resistance. Senescence was induced in HepG2 cells via oxidative stress. The insulin metabolic pathway was studied in control and senescent cells following insulin stimulation. GLUT2 and GLUT4 expressions were studied in HepG2 cells and human liver tissue. Further, GLUT2 and GLUT4 expressions were studied in three independent chronic liver disease cohorts. Signalling impairment distal to Akt in phosphorylation of AS160 and FoxO1 was evident in senescent HepG2 cells. Persistent nuclear localisation of FoxO1 was demonstrated in senescent cells despite insulin stimulation. Increased GLUT4 and decreased GLUT2 expressions were evident in senescent cells, human cirrhotic liver tissue and publically available liver disease datasets. Changes in GLUT expressions were associated with a poor clinical prognosis. In conclusion, selective insulin resistance is evident in senescent HepG2 cells and changes in GLUT expressions can be used as surrogate markers of hepatocyte senescence. - Highlights: • Senescent hepatocytes demonstrate selective insulin resistance. • GLUT changes act as markers of hepatocyte senescence and have prognostic value. • Study offers insight into long noticed intimacy of cirrhosis and insulin resistance

Selective insulin resistance in hepatocyte senescence

Energy Technology Data Exchange (ETDEWEB)

Aravinthan, Aloysious [Division of Gastroenterology and Hepatology, Department of Medicine, University of Cambridge, Cambridge (United Kingdom); Challis, Benjamin [Institute of Metabolic Sciences, University of Cambridge, Cambridge (United Kingdom); Shannon, Nicholas [Cancer Research UK Cambridge Institute, Cambridge (United Kingdom); Hoare, Matthew [Division of Gastroenterology and Hepatology, Department of Medicine, University of Cambridge, Cambridge (United Kingdom); Cancer Research UK Cambridge Institute, Cambridge (United Kingdom); Heaney, Judith [Division of Gastroenterology and Hepatology, Department of Medicine, University of Cambridge, Cambridge (United Kingdom); Foundation for Liver Research, Institute of Hepatology, London (United Kingdom); Alexander, Graeme J.M., E-mail: gja1000@doctors.org.uk [Division of Gastroenterology and Hepatology, Department of Medicine, University of Cambridge, Cambridge (United Kingdom)

2015-02-01

Insulin resistance has been described in association with chronic liver disease for decades. Hepatocyte senescence has been demonstrated in chronic liver disease and as many as 80% of hepatocytes show a senescent phenotype in advanced liver disease. The aim of this study was to understand the role of hepatocyte senescence in the development of insulin resistance. Senescence was induced in HepG2 cells via oxidative stress. The insulin metabolic pathway was studied in control and senescent cells following insulin stimulation. GLUT2 and GLUT4 expressions were studied in HepG2 cells and human liver tissue. Further, GLUT2 and GLUT4 expressions were studied in three independent chronic liver disease cohorts. Signalling impairment distal to Akt in phosphorylation of AS160 and FoxO1 was evident in senescent HepG2 cells. Persistent nuclear localisation of FoxO1 was demonstrated in senescent cells despite insulin stimulation. Increased GLUT4 and decreased GLUT2 expressions were evident in senescent cells, human cirrhotic liver tissue and publically available liver disease datasets. Changes in GLUT expressions were associated with a poor clinical prognosis. In conclusion, selective insulin resistance is evident in senescent HepG2 cells and changes in GLUT expressions can be used as surrogate markers of hepatocyte senescence. - Highlights: • Senescent hepatocytes demonstrate selective insulin resistance. • GLUT changes act as markers of hepatocyte senescence and have prognostic value. • Study offers insight into long noticed intimacy of cirrhosis and insulin resistance.

Expression of glucocorticoid receptor and glucose transporter-1 during placental development in the diabetic rat

Directory of Open Access Journals (Sweden)

Ramazan Demir

2011-07-01

Full Text Available In various tissues, glucocorticoids (GCs are known to downregulate glucose transport systems; however, their effects on glucose transporters (GLUTs in the placenta of a diabetic rat are unknown. Glucocorticoid hormone action within the cell is regulated by the glucocorticoid receptor (GR. Thus, this study was designed to investigate the relationship between GR and glucose transporter expression in the placenta of the diabetic rat. Our immunohistochemical results indicated that GR and glucose transporter protein 1 (GLUT 1 are expressed ubiquitously in the trophoblast and endothelial cells of the labyrinthine zone, where maternal fetal transport takes place in the rat placenta. Expression of GR in the junctional zone of the rat placenta was detected in giant cells, and in some spongiotrophoblast cells, but not in the glycogen cells. GLUT 1 was present, especially in glycogen cells during early pregnancy, and in the spongiotrophoblast cells of the junctional zone during late pregnancy. Amounts of GR and GLUT 1 protein were increased towards the end of gestation both in the control and the diabetic placenta. However, at days 17 and 19 of gestation, only the placental GR protein was significantly increased in the streptozotocin-induced diabetic rats compared to control rats. Diabetes led to a significant decrease in placental weight at gestation day 15. In contrast, at gestational days 17 and 21, the weights of the diabetic placenta were significantly increased as compared with the controls. Moreover, diabetes induced fetus intrauterine growth retardation at gestational days 13, 17 and 21. In conclusion, the localization pattern of GR and GLUT 1 proteins in the same cell types led us to believe that there might be a relationship between GR and GLUT 1 expressions at the cellular level. GLUT 1 does not play a pivotal role in diabetic pregnancies. However, placental growth abnormalities during diabetic pregnancy may be related to the amount of GR

18F-fluorodeoxyglucose and PET/CT for noninvasive study of exercise-induced glucose uptake in rat skeletal muscle and tendon

International Nuclear Information System (INIS)

Skovgaard, Dorthe; Kjaer, Michael; El-Ali, Henrik; Kjaer, Andreas

2009-01-01

To investigate exercise-related glucose uptake in rat muscle and tendon using PET/CT and to study possible explanatory changes in gene expression for the glucose transporters (GLUT1 and GLUT4). The sciatic nerve in eight Wistar rats was subjected to electrostimulation to cause unilateral isometric contractions of the calf muscle. 18 F-Fluorodeoxyglucose was administered and a PET/CT scan of the hindlimbs was performed. SUVs were calculated in both Achilles tendons and the triceps surae muscles. To exclude a spill-over effect the tendons and muscles from an ex vivo group of eight rats were cut out and scanned separately (distance≥1 cm). Muscle contractions increased glucose uptake approximately sevenfold in muscles (p<0.001) and 36% in tendons (p<0.01). The ex vivo group confirmed the increase in glucose uptake in intact animals. GLUT1 and GLUT4 were expressed in both skeletal muscle and tendon, but no changes in mRNA levels could be detected. PET/CT can be used for studying glucose uptake in rat muscle and tendon in relation to muscle contractions; however, the increased uptake of glucose was not explained by changes in gene expression of GLUT1 and GLUT4. (orig.)

Glucose transporter expression differs between bovine monocyte and macrophage subsets and is influenced by milk production.

Science.gov (United States)

Eger, M; Hussen, J; Koy, M; Dänicke, S; Schuberth, H-J; Breves, G

2016-03-01

The peripartal period of dairy cows is characterized by negative energy balance and higher incidences of infectious diseases such as mastitis or metritis. With the onset of lactation, milk production is prioritized and large amounts of glucose are transported into the mammary gland. Decreased overall energy availability might impair the function of monocytes acting as key innate immune cells, which give rise to macrophages and dendritic cells and link innate and adaptive immunity. Information on glucose requirements of bovine immune cells is rare. Therefore, this study aims to evaluate glucose transporter expression of the 3 bovine monocyte subsets (classical, intermediate, and nonclassical monocytes) and monocyte-derived macrophages and to identify influences of the peripartal period. Blood samples were either collected from nonpregnant healthy cows or from 16 peripartal German Holstein cows at d -14, +7, and +21 relative to parturition. Quantitative real-time PCR was applied to determine mRNA expression of glucose transporters (GLUT) 1, GLUT3, and GLUT4 in monocyte subsets and monocyte-derived macrophages. The low GLUT1 and GLUT3 expression in nonclassical monocytes was unaltered during differentiation into macrophages, whereas in classical and intermediate monocytes GLUT expression was downregulated. Alternatively activated M2 macrophages consumed more glucose compared with classically activated M1 macrophages. The GLUT4 mRNA was only detectable in unstimulated macrophages. Neither monocytes nor macrophages were insulin responsive. In the peripartum period, monocyte GLUT1 and GLUT3 expression and the GLUT3/GLUT1 ratio were negatively correlated with lactose production. The high-affinity GLUT3 transporter appears to be the predominant glucose transporter on bovine monocytes and macrophages, especially in the peripartal period when blood glucose levels decline. Glucose transporter expression in monocytes is downregulated as a function of lactose production, which

Effect of physical training on glucose transporter protein and mRNA levels in rat adipocytes

DEFF Research Database (Denmark)

Stallknecht, B; Andersen, P H; Vinten, J

1993-01-01

Physical training increases insulin-stimulated glucose transport and the number of glucose transporters in adipocytes measured by cytochalasin B binding. In the present study we used immunoblotting to measure the abundance of two glucose transporters (GLUT-4, GLUT-1) in white adipocytes from....../or intrinsic activity). GLUT-1 protein and mRNA levels/adipocyte volume did not change with age or training....

Hydrogen improves glycemic control in type1 diabetic animal model by promoting glucose uptake into skeletal muscle.

Directory of Open Access Journals (Sweden)

Haruka Amitani

Full Text Available Hydrogen (H(2 acts as a therapeutic antioxidant. However, there are few reports on H(2 function in other capacities in diabetes mellitus (DM. Therefore, in this study, we investigated the role of H(2 in glucose transport by studying cultured mouse C2C12 cells and human hepatoma Hep-G2 cells in vitro, in addition to three types of diabetic mice [Streptozotocin (STZ-induced type 1 diabetic mice, high-fat diet-induced type 2 diabetic mice, and genetically diabetic db/db mice] in vivo. The results show that H(2 promoted 2-[(14C]-deoxy-d-glucose (2-DG uptake into C2C12 cells via the translocation of glucose transporter Glut4 through activation of phosphatidylinositol-3-OH kinase (PI3K, protein kinase C (PKC, and AMP-activated protein kinase (AMPK, although it did not stimulate the translocation of Glut2 in Hep G2 cells. H(2 significantly increased skeletal muscle membrane Glut4 expression and markedly improved glycemic control in STZ-induced type 1 diabetic mice after chronic intraperitoneal (i.p. and oral (p.o. administration. However, long-term p.o. administration of H(2 had least effect on the obese and non-insulin-dependent type 2 diabetes mouse models. Our study demonstrates that H(2 exerts metabolic effects similar to those of insulin and may be a novel therapeutic alternative to insulin in type 1 diabetes mellitus that can be administered orally.

Glucose transport in brain - effect of inflammation.

Science.gov (United States)

Jurcovicova, J

2014-01-01

Glucose is transported across the cell membrane by specific saturable transport system, which includes two types of glucose transporters: 1) sodium dependent glucose transporters (SGLTs) which transport glucose against its concentration gradient and 2) sodium independent glucose transporters (GLUTs), which transport glucose by facilitative diffusion in its concentration gradient. In the brain, both types of transporters are present with different function, affinity, capacity, and tissue distribution. GLUT1 occurs in brain in two isoforms. The more glycosylated GLUT1 is produced in brain microvasculature and ensures glucose transport across the blood brain barrier (BBB). The less glycosylated form is localized in astrocytic end-feet and cell bodies and is not present in axons, neuronal synapses or microglia. Glucose transported to astrocytes by GLUT1 is metabolized to lactate serving to neurons as energy source. Proinflammatory cytokine interleukin (IL)-1β upregulates GLUT1 in endothelial cells and astrocytes, whereas it induces neuronal death in neuronal cell culture. GLUT2 is present in hypothalamic neurons and serves as a glucose sensor in regulation of food intake. In neurons of the hippocampus, GLUT2 is supposed to regulate synaptic activity and neurotransmitter release. GLUT3 is the most abundant glucose transporter in the brain having five times higher transport capacity than GLUT1. It is present in neuropil, mostly in axons and dendrites. Its density and distribution correlate well with the local cerebral glucose demands. GLUT5 is predominantly fructose transporter. In brain, GLUT5 is the only hexose transporter in microglia, whose regulation is not yet clear. It is not present in neurons. GLUT4 and GLUT8 are insulin-regulated glucose transporters in neuronal cell bodies in the cortex and cerebellum, but mainly in the hippocampus and amygdala, where they maintain hippocampus-dependent cognitive functions. Insulin translocates GLUT4 from cytosol to plasma

Estudio de pacientes con aciduria glutárica tipo II, mediante la incubación de fibroblastos con ácidos palmítico y mirístico tritiados = Study of patients with type II glutaric aciduria by incubation of fibroblasts with tritiated palmitic and myristic acids

Directory of Open Access Journals (Sweden)

Osorio Orozco, José Henry

2011-09-01

Full Text Available Introducción: la aciduria glutárica tipo II, o deficiencia múltiple de acil-CoA deshidrogenasas, es un trastorno causado por deficiencia de la flavoproteína de transferencia de electrones, de su oxidorreductasa o de ambas; se trata de una enfermedad metabólica autosómica recesiva, caracterizada por acidosis, hipoglicemia, aciduria orgánica, olor a pies sudados y malformaciones en cerebro y riñones.Objetivo: analizar las tasas de oxidación de sustratos tritiados por fibroblastos de pacientes con aciduria glutárica tipo II.Materiales y métodos: se incubaron fibroblastos de dos pacientes con aciduria glutárica tipo II y de 20 controles en presencia de ácidos palmítico y mirístico tritiados.Resultados: se encontró muy deprimida (16%-18% la oxidación de los sustratos tritiados por los fibroblastos procedentes de pacientes con aciduria glutárica tipo II en comparación con los controles.Conclusión: la prueba estudiada permite la confirmación in vitro del diagnóstico de aciduria glutárica tipo II.

Adenoviral-mediated placental gene transfer of IGF-1 corrects placental insufficiency via enhanced placental glucose transport mechanisms.

Directory of Open Access Journals (Sweden)

Helen N Jones

Full Text Available Previous work in our laboratory demonstrated that over-expression of human insulin-like growth factor -1 (hIGF-1 in the placenta corrects fetal weight deficits in mouse, rat, and rabbit models of intrauterine growth restriction without changes in placental weight. The underlying mechanisms of this effect have not been elucidated. To investigate the effect of intra-placental IGF-1 over-expression on placental function we examined glucose transporter expression and localization in both a mouse model of IUGR and a model of human trophoblast, the BeWo Choriocarcinoma cell line.At gestational day 18, animals were divided into four groups; sham-operated controls, uterine artery branch ligation (UABL, UABL+Ad-hIGF-1 (10(8 PFU, UABL+Ad-LacZ (10(8 PFU. At gestational day 20, pups and placentas were harvested by C-section. For human studies, BeWo choriocarcinoma cells were grown in F12 complete medium +10%FBS. Cells were incubated in serum-free control media ± Ad-IGF-1 or Ad-LacZ for 48 hours. MOIs of 10∶1 and 100∶1 were utilized. The RNA, protein expression and localization of glucose transporters GLUT1, 3, 8, and 9 were analyzed by RT-PCR, Western blot and immunohistochemistry.In both the mouse placenta and BeWo, GLUT1 regulation was linked to altered protein localization. GLUT3, localized to the mouse fetal endothelial cells, was reduced in placental insufficiency but maintained with Ad-I GF-1 treatment. Interestingly, GLUT8 expression was reduced in the UABL placenta but up-regulated following Ad-IGF-1 in both mouse and human systems. GLUT9 expression in the mouse was increased by Ad-IGF-1 but this was not reflected in the BeWo, where Ad-IGF-1 caused moderate membrane relocalization.Enhanced GLUT isoform transporter expression and relocalization to the membrane may be an important mechanism in Ad-hIGF-1mediated correction of placental insufficiency.

Differential Role of Insulin/IGF-1 Receptor Signaling in Muscle Growth and Glucose Homeostasis

Directory of Open Access Journals (Sweden)

Brian T. O’Neill

2015-05-01

Full Text Available Insulin and insulin-like growth factor 1 (IGF-1 are major regulators of muscle protein and glucose homeostasis. To determine how these pathways interact, we generated mice with muscle-specific knockout of IGF-1 receptor (IGF1R and insulin receptor (IR. These MIGIRKO mice showed >60% decrease in muscle mass. Despite a complete lack of insulin/IGF-1 signaling in muscle, MIGIRKO mice displayed normal glucose and insulin tolerance. Indeed, MIGIRKO mice showed fasting hypoglycemia and increased basal glucose uptake. This was secondary to decreased TBC1D1 resulting in increased Glut4 and Glut1 membrane localization. Interestingly, overexpression of a dominant-negative IGF1R in muscle induced glucose intolerance in MIGIRKO animals. Thus, loss of insulin/IGF-1 signaling impairs muscle growth, but not whole-body glucose tolerance due to increased membrane localization of glucose transporters. Nonetheless, presence of a dominant-negative receptor, even in the absence of functional IR/IGF1R, induces glucose intolerance, indicating that interactions between these receptors and other proteins in muscle can impair glucose homeostasis.

SIK2 regulates CRTCs, HDAC4 and glucose uptake in adipocytes

DEFF Research Database (Denmark)

Henriksson, Emma; Säll, Johanna; Gormand, Amélie

2015-01-01

regulation in human adipocytes, strengthening the physiological relevance of our findings. Collectively, we demonstrate that SIK2 acts directly on CRTC2, CRTC3 and HDAC4, and that cAMP/PKA reduces the interaction of SIK2 with CRTCs and PP2A. Downstream, SIK2 promotes GLUT4 levels and glucose uptake...

High-fat diet with stress impaired islets' insulin secretion by reducing plasma estradiol and pancreatic GLUT2 protein levels in rats' proestrus phase.

Science.gov (United States)

Salimi, M; Zardooz, H; Khodagholi, F; Rostamkhani, F; Shaerzadeh, F

2016-10-01

This study was conducted to determine whether two estrus phases (proestrus and diestrus) in female rats may influence the metabolic response to a high-fat diet and/or stress, focusing on pancreatic insulin secretion and content. Animals were divided into high-fat and normal diet groups, then each group was subdivided into stress and non-stress groups, and finally, each one of these was divided into proestrus and diestrus subgroups. At the end of high-fat diet treatment, foot-shock stress was applied to the animals. Then, blood samples were taken to measure plasma factors. Finally, the pancreas was removed for determination of glucose transporter 2 (GLUT2) protein levels and assessment of insulin content and secretion of the isolated islets. In the normal and high-fat diet groups, stress increased plasma corticosterone concentration in both phases. In both study phases, high-fat diet consumption decreased estradiol and increased leptin plasma levels. In the high-fat diet group in response to high glucose concentration, a reduction in insulin secretion was observed in the proestrus phase compared with the same phase in the normal diet group in the presence and absence of stress. Also, high-fat diet decreased the insulin content of islets in the proestrus phase compared with the normal diet. High-fat diet and/or stress caused a reduction in islet GLUT2 protein levels in both phases. In conclusion, it seems possible that high-fat diet alone or combined with foot-shock, predispose female rats to impaired insulin secretion, at least in part, by interfering with estradiol levels in the proestrus phase and decreasing pancreatic GLUT2 protein levels.

Diversity in the glucose transporter-4 gene (SLC2A4 in humans reflects the action of natural selection along the old-world primates evolution.

Directory of Open Access Journals (Sweden)

Eduardo Tarazona-Santos

Full Text Available BACKGROUND: Glucose is an important source of energy for living organisms. In vertebrates it is ingested with the diet and transported into the cells by conserved mechanisms and molecules, such as the trans-membrane Glucose Transporters (GLUTs. Members of this family have tissue specific expression, biochemical properties and physiologic functions that together regulate glucose levels and distribution. GLUT4 -coded by SLC2A4 (17p13 is an insulin-sensitive transporter with a critical role in glucose homeostasis and diabetes pathogenesis, preferentially expressed in the adipose tissue, heart muscle and skeletal muscle. We tested the hypothesis that natural selection acted on SLC2A4. METHODOLOGY/PRINCIPAL FINDINGS: We re-sequenced SLC2A4 and genotyped 104 SNPs along a approximately 1 Mb region flanking this gene in 102 ethnically diverse individuals. Across the studied populations (African, European, Asian and Latin-American, all the eight common SNPs are concentrated in the N-terminal region upstream of exon 7 ( approximately 3700 bp, while the C-terminal region downstream of intron 6 ( approximately 2600 bp harbors only 6 singletons, a pattern that is not compatible with neutrality for this part of the gene. Tests of neutrality based on comparative genomics suggest that: (1 episodes of natural selection (likely a selective sweep predating the coalescent of human lineages, within the last 25 million years, account for the observed reduced diversity downstream of intron 6 and, (2 the target of natural selection may not be in the SLC2A4 coding sequence. CONCLUSIONS: We propose that the contrast in the pattern of genetic variation between the N-terminal and C-terminal regions are signatures of the action of natural selection and thus follow-up studies should investigate the functional importance of different regions of the SLC2A4 gene.

LMP1-mediated glycolysis induces myeloid-derived suppressor cell expansion in nasopharyngeal carcinoma.

Directory of Open Access Journals (Sweden)

Ting-Ting Cai

2017-07-01

Full Text Available Myeloid-derived suppressor cells (MDSCs are expanded in tumor microenvironments, including that of Epstein-Barr virus (EBV-associated nasopharyngeal carcinoma (NPC. The link between MDSC expansion and EBV infection in NPC is unclear. Here, we show that EBV latent membrane protein 1 (LMP1 promotes MDSC expansion in the tumor microenvironment by promoting extra-mitochondrial glycolysis in malignant cells, which is a scenario for immune escape initially suggested by the frequent, concomitant detection of abundant LMP1, glucose transporter 1 (GLUT1 and CD33+ MDSCs in tumor sections. The full process has been reconstituted in vitro. LMP1 promotes the expression of multiple glycolytic genes, including GLUT1. This metabolic reprogramming results in increased expression of the Nod-like receptor family protein 3 (NLRP3 inflammasome, COX-2 and P-p65 and, consequently, increased production of IL-1β, IL-6 and GM-CSF. Finally, these changes in the environment of malignant cells result in enhanced NPC-derived MDSC induction. One key step is the physical interaction of LMP1 with GLUT1 to stabilize the GLUT1 protein by blocking its K48-ubiquitination and p62-dependent autolysosomal degradation. This work indicates that LMP1-mediated glycolysis regulates IL-1β, IL-6 and GM-CSF production through the NLRP3 inflammasome, COX-2 and P-p65 signaling pathways to enhance tumor-associated MDSC expansion, which leads to tumor immunosuppression in NPC.

Glucose Transporter 1 Expression in Odontogenic Keratocyst, Dentigerous Cyst, and Ameloblastoma: An Immunohistochemical Study.

Science.gov (United States)

Bandyopadhyay, Alokenath; Panda, Abikshyeet; Behura, Shyam S; Ramachandra, Sujatha; Dash, Kailash C; Mishra, Pallavi

2017-05-01

An array of odontogenic lesions manifest in the maxillofacial region with variable presentations. The biological behavior of lesions, such as odontogenic keratocyst (OKC), dentigerous cyst (DC), and ameloblastoma (AM) always invite debate. Glucose transporter 1 (GLUT-1) is proven to be an indicator of metabolic behavior of several benign and malignant neoplasms. The purpose of this study was to evaluate the expression of GLUT-1 in OKC, DC, and AM to understand their metabolic behavior. Immunohistochemical expression of GLUT-1 was evaluated in each of the 15 cases of OKC, DC, and AM. The number of labeled cells, staining intensity, and membrane or cytoplasmic expressions were the parameters assessed and analyzed using chi-square test. All cases showed positive GLUT-1 expression: 86.6% OKC showed more than 50% labeled cells followed by DC (40%) and AM (26.5%); 53.3% OKC showed strong intensity in comparison to AM, which showed weak intensity in 53.3% cases; 86.6% of OKCs showed both membrane and cytoplasmic expression followed by DC (40%) and AM (26.6%), whereas 73.3% of AM showed only membrane expression followed by DC (60%) and OKC (13.3%). Odontogenic keratocyst was found out to be more metabolically active followed by DC and AM.

Experimental study of the molecular mechanisms of myocardial ischemic memory with 18F-FDG PET/CT imaging

International Nuclear Information System (INIS)

Xie Boqia; Yang Minfu; Ye Jue; Yang Zihe; Dou Kefei; Tian Yi; Han Chunlei

2012-01-01

This study was aimed to explore whether the changes of mRNA and the existence and duration of ischemic 18 F-FDG uptake correlate with the extent of myocardial ischemia in ischemia-reperfusion canine model. The 20-minute (n= 4) and 40-minute (n=4) coronary artery occlusion followed by 24 h of open-artery reperfusion in canine model were per- formed. All dogs underwent fasting (>12 h) dynamic 18 F-FDG PET/CT and 99 Tc m -MIBI SPECT imaging at baseline, 1 h and 24 h after reperfusion. When all imaging were completed, myocardial samples from the ischemic and nonischemic region were obtained, and the mRNA expression of glucose transporter-l (GLUT-1), glucose transporter-4 (GLUT-4), and heart-fatty acid binding protein (H-FABP) were estimated by Real Time PCR. There was no difference in the ratio of hypoperfused region/nomoperfused region of 18 F-FDG up- take between the 20-minute group and 40-minute group at baseline. When examined at 1 h, increased 18 F-FDG uptake was observed in the 40-minute group. When estimated at 24 h, only the 40-minute group showed slightly higher 18 F-FDG uptake than baseline, whereas no such difference was demonstrated in the 20-minute group. Similar mRNA expression of GLUT-1, GLUT-4 and H-FABP were demonstrated in the nonischemic regions between the 2 groups, whereas increased expressions of GLUT-1 and GLUT-4, and decreased H-FABP mRNA were demonstrated in the ischemic regions. The changes of mRNA expression were more obvious in the 40 minute group than in the 20-minute group. The results showed that the existence and persistent period of ischemic 18 F-FDG uptake (ischemic memory) was correlated with the extent of myocardial ischemia. (authors)

Rac1 Activation Caused by Membrane Translocation of a Guanine Nucleotide Exchange Factor in Akt2-Mediated Insulin Signaling in Mouse Skeletal Muscle.

Directory of Open Access Journals (Sweden)

Nobuyuki Takenaka

Full Text Available Insulin-stimulated glucose uptake in skeletal muscle is mediated by the glucose transporter GLUT4, which is translocated to the plasma membrane following insulin stimulation. Several lines of evidence suggested that the protein kinase Akt2 plays a key role in this insulin action. The small GTPase Rac1 has also been implicated as a regulator of insulin-stimulated GLUT4 translocation, acting downstream of Akt2. However, the mechanisms whereby Akt2 regulates Rac1 activity remain obscure. The guanine nucleotide exchange factor FLJ00068 has been identified as a direct regulator of Rac1 in Akt2-mediated signaling, but its characterization was performed mostly in cultured myoblasts. Here, we provide in vivo evidence that FLJ00068 indeed acts downstream of Akt2 as a Rac1 regulator by using mouse skeletal muscle. Small interfering RNA knockdown of FLJ00068 markedly diminished GLUT4 translocation to the sarcolemma following insulin administration or ectopic expression of a constitutively activated mutant of either phosphoinositide 3-kinase or Akt2. Additionally, insulin and these constitutively activated mutants caused the activation of Rac1 as shown by immunofluorescent microscopy using a polypeptide probe specific to activated Rac1 in isolated gastrocnemius muscle fibers and frozen sections of gastrocnemius muscle. This Rac1 activation was also abrogated by FLJ00068 knockdown. Furthermore, we observed translocation of FLJ00068 to the cell periphery following insulin stimulation in cultured myoblasts. Localization of FLJ00068 in the plasma membrane in insulin-stimulated, but not unstimulated, myoblasts and mouse gastrocnemius muscle was further affirmed by subcellular fractionation and subsequent immunoblotting. Collectively, these results strongly support a critical role of FLJ00068 in Akt2-mediated Rac1 activation in mouse skeletal muscle insulin signaling.

Gibbs Free-Energy Gradient along the Path of Glucose Transport through Human Glucose Transporter 3.

Science.gov (United States)

Liang, Huiyun; Bourdon, Allen K; Chen, Liao Y; Phelix, Clyde F; Perry, George

2018-06-11

Fourteen glucose transporters (GLUTs) play essential roles in human physiology by facilitating glucose diffusion across the cell membrane. Due to its central role in the energy metabolism of the central nervous system, GLUT3 has been thoroughly investigated. However, the Gibbs free-energy gradient (what drives the facilitated diffusion of glucose) has not been mapped out along the transport path. Some fundamental questions remain. Here we present a molecular dynamics study of GLUT3 embedded in a lipid bilayer to quantify the free-energy profile along the entire transport path of attracting a β-d-glucose from the interstitium to the inside of GLUT3 and, from there, releasing it to the cytoplasm by Arrhenius thermal activation. From the free-energy profile, we elucidate the unique Michaelis-Menten characteristics of GLUT3, low K M and high V MAX , specifically suitable for neurons' high and constant demand of energy from their low-glucose environments. We compute GLUT3's binding free energy for β-d-glucose to be -4.6 kcal/mol in agreement with the experimental value of -4.4 kcal/mol ( K M = 1.4 mM). We also compute the hydration energy of β-d-glucose, -18.0 kcal/mol vs the experimental data, -17.8 kcal/mol. In this, we establish a dynamics-based connection from GLUT3's crystal structure to its cellular thermodynamics with quantitative accuracy. We predict equal Arrhenius barriers for glucose uptake and efflux through GLUT3 to be tested in future experiments.

The ontogeny of insulin signaling in the preterm baboon model.

Science.gov (United States)

Blanco, Cynthia L; Liang, Hanyu; Joya-Galeana, Joaquin; DeFronzo, Ralph A; McCurnin, Donald; Musi, Nicolas

2010-05-01

Hyperglycemia, a prevalent condition in premature infants, is thought to be a consequence of incomplete suppression of endogenous glucose production and reduced insulin-stimulated glucose disposal in peripheral tissues. However, the molecular basis for these conditions remains unclear. To test the hypothesis that the insulin transduction pathway is underdeveloped with prematurity, fetal baboons were delivered, anesthetized, and euthanized at 125 d gestational age (GA), 140 d GA, or near term at 175 d GA. Vastus lateralis muscle and liver tissues were obtained, and protein content of insulin signaling molecules [insulin receptor (IR)-beta, IR substate-1, p85 subunit of phosphatidylinositol 3-kinase, Akt, and AS160] and glucose transporters (GLUT)-1 and GLUT4 was measured by Western blotting. Muscle from 125 d GA baboons had markedly reduced GLUT1 protein content (16% of 140 d GA and 9% of 175 d GA fetuses). GLUT4 and AS160 also were severely reduced in 125 d GA fetal muscle (43% of 175 d GA and 35% of 175 d GA, respectively). In contrast, the protein content of IR-beta, IR substate-1, and Akt was elevated by 1.7-, 5.2-, and 1.9-fold, respectively, in muscle from 125 d GA baboons when compared with 175 d GA fetuses. No differences were found in the content of insulin signaling proteins in liver. In conclusion, significant gestational differences exist in the protein content of several insulin signaling proteins in the muscle of fetal baboons. Reduced muscle content of key glucose transport-regulating proteins (GLUT1, GLUT4, AS160) could play a role in the pathogenesis of neonatal hyperglycemia and reduced insulin-stimulated glucose disposal.

l-Cysteine supplementation increases insulin sensitivity mediated by upregulation of GSH and adiponectin in high glucose treated 3T3-L1 adipocytes.

Science.gov (United States)

Achari, Arunkumar E; Jain, Sushil K

2017-09-15

Diabetic patients have lower blood levels of l-cysteine (LC) and glutathione (GSH). This study examined the hypothesis that LC supplementation positively up regulates the effects of insulin on GSH and glucose metabolism in 3T3-L1 adipocyte model. 3T3L1 adipocytes were treated with LC (250 μM, 2 h) and/or insulin (15 or 30 nM, 2 h), and high glucose (HG, 25 mM, 20 h). Results showed that HG caused significant increase (95%) in ROS and reduction in the protein levels of DsbA-L (43%), adiponectin (64%), GCLC (20%), GCLM (21%), GSH (50%), and GLUT-4 (23%) in adipocytes. Furthermore, HG caused a reduction in total (35%) and HMW adiponectin (30%) secretion. Treatment with insulin alone significantly (p L, adiponectin, GCLC, GCLM, GSH, and GLUT-4 protein levels, glucose utilization, and improved total and HMW adiponectin secretion in HG treated adipocytes compared to HG alone. Interestingly, LC supplementation along with insulin caused greater reduction in ROS levels and significantly (p L (41% vs LC, 29% vs Insulin), adiponectin (92% Vs LC, 84% Vs insulin) protein levels and total (32% Vs LC, 22% Vs insulin) and HMW adiponectin (75% Vs LC, 39% Vs insulin) secretion compared with the either insulin or LC alone in HG-treated cells. In addition, LC supplementation along with insulin increased GCLC (21% Vs LC, 14% insulin), GCLM (28% Vs LC, 16% insulin) and GSH (25% Vs LC and insulin) levels compared with the either insulin or LC alone in HG-treated cells. Furthermore, LC and insulin increases GLUT-4 protein expression (65% Vs LC, 18% Vs Insulin), glucose utilization (57% Vs LC, 27% Vs insulin) compared with the either insulin or LC alone in HG-treated cells. Similarly, LC supplementation increased insulin action significantly in cells maintained in medium contained control glucose. To explore the beneficial effect of LC is mediated by the upregulation of GCLC, we knocked down GCLC using siRNA in adipoctyes. There was a significant decrease in DsbA-L and GLUT-4 m

Termoativação da transaminase glutâmico oxaloacética

Directory of Open Access Journals (Sweden)

Hélion Póvoa Júnior

1973-01-01

Full Text Available Estudou-se a atividade da transaminase glutâmico oxaloacética (TGO em diferentes tecidos (fígado, músculo, rim, pulmão, baço e soro sanguíneo de ratos e de soro humano. verificou-se que a atividade da enzima proveniente de qualquer um destes tecidos é aumentada cerca de tr~es vezes quando a incubação se faz a 60ºC, ao invés de 37ºC. São feitas considerações acerca da importância deste fato.Glutamic Oxalacetic transaminase is thermoativated. Its optimum of catalytical activity is at 60ºC. At this temperature, colour is approximately three times more intense than at 37ºC, temperature usually utilized for determination of enzyme activity. This phenomenon is observed in human blood serum and several rat tissues (liver, heart, striated muscle, spleen, lung, kidney and blood serum.

Efeitos do ácido L-glutâmico e da vitamina K na composição bioquímica parcial de fêmures de frangos de corte Effects of dietary L-glutamic acid and K vitamin in the biochemical composition in femurs of broilers at 14 days of age

Directory of Open Access Journals (Sweden)

George Henrique Kling de Moraes

2010-04-01

Full Text Available Objetivou-se estudar os efeitos da combinação de ácido L-glutâmico (L-Glu e vitamina K na composição bioquímica de fêmures (proteínas colagenosas; não-colagenosas e totais de frangos de corte. O experimento, que teve 14 dias de duração, foi conduzido em delineamento inteiramente casualizado, em fatorial 2 × 4, com dois níveis de ácido L-glutâmico (6,25 e 12,5% combinados com quatro níveis de vitamina K (0,02; 0,2; 2,0 e 20,0 mg/kg de ração, cada combinação com quatro repetições de dez animais. Foram utilizados pintos machos, Avian Farm, de 1 dia, criados em baterias aquecidas e alimentados à vontade com dieta básica contendo L-aminoácidos essenciais, minerais e vitaminas (exceto vitamina K suplementada com ácido L-glutâmico e vitamina K. Ao término do experimento, os animais foram sacrificados por deslocamento cervical e seus fêmures removidos, medidos, desengordurados e pesados. Não foi observada interação significativa entre ácido L-glutâmico e vitamina K para os parâmetros estudados. Os teores de proteínas não-colagenosas foram maiores e o de proteínas colagenosas, menores nos fêmures dos pintos alimentados com a ração com 6,25% de ácido L-glutâmico. Os teores de proteínas totais, no entanto, não foram afetados pelos níveis de ácido L-glutâmico e de vitamina K. Os níveis de vitamina K tiveram efeito quadrático decrescente nos teores de proteínas não-colagenosas e efeito crescente na composição de proteínas colagenosas dos fêmures. A composição em proteínas colagenosas e não-colagenosas pode ser utilizada como indicador bioquímico de anormalidades de pernas causadas por baixo nível de nitrogênio não-específico.This work aimed to study the effects of L-glutamic acid (L-Glu and K vitamin on the biochemical composition (collagenous proteins, CP; non collagenous proteins, NCP; and total proteins, TP in femurs of broilers. The experiment which lasted for 14 days, was carried out in a

Ptpmt1 induced by HIF-2α regulates the proliferation and glucose metabolism in erythroleukemia cells

Energy Technology Data Exchange (ETDEWEB)

Xu, Qin-Qin [High Altitude Medicine of Ministry of Chinese Education and Research Center for High Altitude Medicine, Qinghai University, Xining, 810001 (China); Qinghai Provincial People' s Hospital, Xining (China); Xiao, Feng-Jun; Sun, Hui-Yan [Department of Experimental Hematology, Beijing Institute of Radiation Medicine, Beijing, 100850 (China); Shi, Xue-Feng [High Altitude Medicine of Ministry of Chinese Education and Research Center for High Altitude Medicine, Qinghai University, Xining, 810001 (China); Qinghai Provincial People' s Hospital, Xining (China); Wang, Hua; Yang, Yue-Feng; Li, Yu-Xiang [Department of Experimental Hematology, Beijing Institute of Radiation Medicine, Beijing, 100850 (China); Wang, Li-Sheng, E-mail: wangls@bmi.ac.cn [Department of Experimental Hematology, Beijing Institute of Radiation Medicine, Beijing, 100850 (China); Ge, Ri-Li, E-mail: geriligao@hotmail.com [High Altitude Medicine of Ministry of Chinese Education and Research Center for High Altitude Medicine, Qinghai University, Xining, 810001 (China)

2016-03-18

Hypoxia provokes metabolism misbalance, mitochondrial dysfunction and oxidative stress in both human and animal cells. However, the mechanisms which hypoxia causes mitochondrial dysfunction and energy metabolism misbalance still remain unclear. In this study, we presented evidence that mitochondrial phosphatase Ptpmt1 is a hypoxia response molecule that regulates cell proliferation, survival and glucose metabolism in human erythroleukemia TF-1 cells. Exposure to hypoxia or DFO treatment results in upregulation of HIF1-α, HIF-2α and Ptpmt1. Only inhibition of HIF-2α by shRNA transduction reduces Ptpmt1 expression in TF-1 cells under hypoxia. Ptpmt1 inhibitor suppresses the growth and induces apoptosis of TF-1 cells. Furthermore, we demonstrated that Ptpmt1 inhibition reduces the Glut1 and Glut3 expression and decreases the glucose consumption in TF-1 cells. In additional, Ptpmt1 knockdown also results in the mitochondrial dysfunction determined by JC1 staining. These results delineate a key role for HIF-2α-induced Ptpmt1 upregulation in proliferation, survival and glucose metabolism of erythroleukemia cells. It is indicated that Ptpmt1 plays important roles in hypoxia-induced cell metabolism and mitochondrial dysfunction. - Highlights: • Hypoxia induces upregulation of HIF-1α, HIF-2α and Ptpmt1; HIF-2a induces Ptpmt1 upregulation in TF-1 cells. • PTPMT-1 inhibition reduces growth and induces apoptosis of TF-1 cells. • PTPMT1 inhibition downregulates Glut-1, Glut-3 expression and reduces glucose consumption.

Regulation of myosin IIA and filamentous actin during insulin-stimulated glucose uptake in 3T3-L1 adipocytes

International Nuclear Information System (INIS)

Stall, Richard; Ramos, Joseph; Kent Fulcher, F.; Patel, Yashomati M.

2014-01-01

Insulin stimulated glucose uptake requires the colocalization of myosin IIA (MyoIIA) and the insulin-responsive glucose transporter 4 (GLUT4) at the plasma membrane for proper GLUT4 fusion. MyoIIA facilitates filamentous actin (F-actin) reorganization in various cell types. In adipocytes F-actin reorganization is required for insulin-stimulated glucose uptake. What is not known is whether MyoIIA interacts with F-actin to regulate insulin-induced GLUT4 fusion at the plasma membrane. To elucidate the relationship between MyoIIA and F-actin, we examined the colocalization of MyoIIA and F-actin at the plasma membrane upon insulin stimulation as well as the regulation of this interaction. Our findings demonstrated that MyoIIA and F-actin colocalized at the site of GLUT4 fusion with the plasma membrane upon insulin stimulation. Furthermore, inhibition of MyoII with blebbistatin impaired F-actin localization at the plasma membrane. Next we examined the regulatory role of calcium in MyoIIA-F-actin colocalization. Reduced calcium or calmodulin levels decreased colocalization of MyoIIA and F-actin at the plasma membrane. While calcium alone can translocate MyoIIA it did not stimulate F-actin accumulation at the plasma membrane. Taken together, we established that while MyoIIA activity is required for F-actin localization at the plasma membrane, it alone is insufficient to localize F-actin to the plasma membrane. - Highlights: • Insulin induces colocalization of MyoIIA and F-actin at the cortex in adipocytes. • MyoIIA is necessary but not sufficient to localize F-actin at the cell cortex. • MyoIIA-F-actin colocalization is regulated by calcium and calmodulin

[Value of immunocytochemistry in differential diagnosis of gastric adenocarcinoma, reactive mesothelial cells and malignant epithelial mesothelioma in metastatic effusion fluid].

Science.gov (United States)

Lyu, M; Cha, N; Zou, Y F; Leng, J H; Xu, L; Sun, Y; Hao, Y Y

2018-03-08

Objective: To investigate the diagnostic value of some antibodies in peritoneal fluid of patients with gastric cancer and malignant epithelioid mesothelioma in serous effusion. Methods: One hundred and eighty-two cases of serous effusion were collected at Jilin Cancer Hospital, from July 2012 to July 2016. The expression of GLUT1, CDX2, Villin, calretinin and WT1 was evaluated using SP immunocytochemical technique in peritoneal fluid samples collected from 98 patients with gastric cancer and 74 patients with reactive mesothelial cells. The expression of GLUT1, calretinin and WT1 was also evaluated in serous effusion from 10 patients with mesothelioma. Results: The sensitivity of GLUT1, CDX2 and Villin in adenocarcinoma cells was 91.8%(90/98), 68.4% (67/98) and 88.8%(87/98), respectively. The specificity was 95.9% (71/74), 100.0%(74/74) and 100.0% (74/74), respectively. The sensitivity of calretinin and WT1 for reactive mesothelium was 93.2% (69/74) and 79.7% (59/74), respectively. The specificity was 96.9% (95/98) and 100.0% (98/98), respectively. The sensitivity of GLUT1, calretinin and WT1 for mesothelioma was 9/10, 9/10 and 7/10. The reactivity of GLUT1, CDX2, Villin, calretinin and WT1 showed a significant difference ( P <0.01) between adenocarcinoma cells and reactive mesothelium. The reactivity of GLUT1 showed a significant difference ( P <0.01) between mesothelioma and reactive mesothelium. Conclusions: The optimal combination is a panel of GLUT1, CDX2, Villin, calretinin and WT1 for differential diagnosis between adenocarcinoma cells and reactive mesothelium in peritoneal fluid of patients with gastric cancer. Whereas GLUT1, calretinin and WT1 is the best for differential diagnosis between reactive mesothelium and mesothelioma in serous effusions.

Myostatin inhibition therapy for insulin-deficient type 1 diabetes.

Science.gov (United States)

Coleman, Samantha K; Rebalka, Irena A; D'Souza, Donna M; Deodhare, Namita; Desjardins, Eric M; Hawke, Thomas J

2016-09-01

While Type 1 Diabetes Mellitus (T1DM) is characterized by hypoinsulinemia and hyperglycemia, persons with T1DM also develop insulin resistance. Recent studies have demonstrated that insulin resistance in T1DM is a primary mediator of the micro and macrovascular complications that invariably develop in this chronic disease. Myostatin acts to attenuate muscle growth and has been demonstrated to be elevated in streptozotocin-induced diabetic models. We hypothesized that a reduction in mRNA expression of myostatin within a genetic T1DM mouse model would improve skeletal muscle health, resulting in a larger, more insulin sensitive muscle mass. To that end, Akita diabetic mice were crossed with Myostatin(Ln/Ln) mice to ultimately generate a novel mouse line. Our data support the hypothesis that decreased skeletal muscle expression of myostatin mRNA prevented the loss of muscle mass observed in T1DM. Furthermore, reductions in myostatin mRNA increased Glut1 and Glut4 protein expression and glucose uptake in response to an insulin tolerance test (ITT). These positive changes lead to significant reductions in resting blood glucose levels as well as pronounced reductions in associated diabetic symptoms, even in the absence of exogenous insulin. Taken together, this study provides a foundation for considering myostatin inhibition as an adjuvant therapy in T1DM as a means to improve insulin sensitivity and blood glucose management.

Cinnamon Extract Enhances Glucose Uptake in 3T3-L1 Adipocytes and C2C12 Myocytes by Inducing LKB1-AMP-Activated Protein Kinase Signaling

Science.gov (United States)

Shen, Yan; Honma, Natsumi; Kobayashi, Katsuya; Jia, Liu Nan; Hosono, Takashi; Shindo, Kazutoshi; Ariga, Toyohiko; Seki, Taiichiro

2014-01-01

We previously demonstrated that cinnamon extract (CE) ameliorates type 1 diabetes induced by streptozotocin in rats through the up-regulation of glucose transporter 4 (GLUT4) translocation in both muscle and adipose tissues. This present study was aimed at clarifying the detailed mechanism(s) with which CE increases the glucose uptake in vivo and in cell culture systems using 3T3-L1 adipocytes and C2C12 myotubes in vitro. Specific inhibitors of key enzymes in insulin signaling and AMP-activated protein kinase (AMPK) signaling pathways, as well as small interference RNA, were used to examine the role of these kinases in the CE-induced glucose uptake. The results showed that CE stimulated the phosphorylation of AMPK and acetyl-CoA carboxylase. An AMPK inhibitor and LKB1 siRNA blocked the CE-induced glucose uptake. We also found for the first time that insulin suppressed AMPK activation in the adipocyte. To investigate the effect of CE on type 2 diabetes in vivo, we further performed oral glucose tolerance tests and insulin tolerance tests in type 2 diabetes model rats administered with CE. The CE improved glucose tolerance in oral glucose tolerance tests, but not insulin sensitivity in insulin tolerance test. In summary, these results indicate that CE ameliorates type 2 diabetes by inducing GLUT4 translocation via the AMPK signaling pathway. We also found insulin antagonistically regulates the activation of AMPK. PMID:24551069

Effect of in vivo injection of cholera and pertussis toxin on glucose transport in rat skeletal muscle

DEFF Research Database (Denmark)

Ploug, Thorkil; Han, X; Petersen, L N

1997-01-01

Cholera toxin (CTX) and pertussis toxin (PTX) were examined for their ability to inhibit glucose transport in perfused skeletal muscle. Twenty-five hours after an intravenous injection of CTX, basal transport was decreased approximately 30%, and insulin- and contraction-stimulated transport...... in GLUT-1 protein content was found. In contrast, GLUT-4 mRNA was unchanged, but transcripts for GLUT-1 were increased > or = 150% in all three muscles from CTX-treated rats. The findings suggest that CTX via increased cAMP impairs basal as well as insulin- and contraction-stimulated muscle glucose...

Topography of brain glucose hypometabolism and epileptic network in glucose transporter 1 deficiency.

Science.gov (United States)

Akman, Cigdem Inan; Provenzano, Frank; Wang, Dong; Engelstad, Kristin; Hinton, Veronica; Yu, Julia; Tikofsky, Ronald; Ichese, Masonari; De Vivo, Darryl C

2015-02-01

(18)F fluorodeoxyglucose positron emission tomography ((18)F FDG-PET) facilitates examination of glucose metabolism. Previously, we described regional cerebral glucose hypometabolism using (18)F FDG-PET in patients with Glucose transporter 1 Deficiency Syndrome (Glut1 DS). We now expand this observation in Glut1 DS using quantitative image analysis to identify the epileptic network based on the regional distribution of glucose hypometabolism. (18)F FDG-PET scans of 16 Glut1 DS patients and 7 healthy participants were examined using Statistical parametric Mapping (SPM). Summed images were preprocessed for statistical analysis using MATLAB 7.1 and SPM 2 software. Region of interest (ROI) analysis was performed to validate SPM results. Visual analysis of the (18)F FDG-PET images demonstrated prominent regional glucose hypometabolism in the thalamus, neocortical regions and cerebellum bilaterally. Group comparison using SPM analysis confirmed that the regional distribution of glucose hypo-metabolism was present in thalamus, cerebellum, temporal cortex and central lobule. Two mildly affected patients without epilepsy had hypometabolism in cerebellum, inferior frontal cortex, and temporal lobe, but not thalamus. Glucose hypometabolism did not correlate with age at the time of PET imaging, head circumference, CSF glucose concentration at the time of diagnosis, RBC glucose uptake, or CNS score. Quantitative analysis of (18)F FDG-PET imaging in Glut1 DS patients confirmed that hypometabolism was present symmetrically in thalamus, cerebellum, frontal and temporal cortex. The hypometabolism in thalamus correlated with the clinical history of epilepsy. Copyright © 2014. Published by Elsevier B.V.

Comparative study of expression and activity of glucose transporters between stem cell-derived brain microvascular endothelial cells and hCMEC/D3 cells.

Science.gov (United States)

Al-Ahmad, Abraham J

2017-10-01

Glucose constitutes a major source of energy of mammalian brains. Glucose uptake at the blood-brain barrier (BBB) occurs through a facilitated glucose transport, through glucose transporter 1 (GLUT1), although other isoforms have been described at the BBB. Mutations in GLUT1 are associated with the GLUT1 deficiency syndrome, yet none of the current in vitro models of the human BBB maybe suited for modeling such a disorder. In this study, we investigated the expression of glucose transporters and glucose diffusion across brain microvascular endothelial cells (BMECs) derived from healthy patient-derived induced pluripotent stem cells (iPSCs). We investigated the expression of different glucose transporters at the BBB using immunocytochemistry and flow cytometry and measured glucose uptake and diffusion across BMEC monolayers obtained from two iPSC lines and from hCMEC/D3 cells. BMEC monolayers showed expression of several glucose transporters, in particular GLUT1, GLUT3, and GLUT4. Diffusion of glucose across the monolayers was mediated via a saturable transcellular mechanism and partially inhibited by pharmacological inhibitors. Taken together, our study suggests the presence of several glucose transporters isoforms at the human BBB and demonstrates the feasibility of modeling glucose across the BBB using patient-derived stem cells. Copyright © 2017 the American Physiological Society.

Biomolecular Characterization of Putative Antidiabetic Herbal Extracts

Science.gov (United States)

Stadlbauer, Verena; Haselgrübler, Renate; Lanzerstorfer, Peter; Plochberger, Birgit; Borgmann, Daniela; Jacak, Jaroslaw; Winkler, Stephan M.; Schröder, Klaus; Höglinger, Otmar; Weghuber, Julian

2016-01-01

Induction of GLUT4 translocation in the absence of insulin is considered a key concept to decrease elevated blood glucose levels in diabetics. Due to the lack of pharmaceuticals that specifically increase the uptake of glucose from the blood circuit, application of natural compounds might be an alternative strategy. However, the effects and mechanisms of action remain unknown for many of those substances. For this study we investigated extracts prepared from seven different plants, which have been reported to exhibit anti-diabetic effects, for their GLUT4 translocation inducing properties. Quantitation of GLUT4 translocation was determined by total internal reflection fluorescence (TIRF) microscopy in insulin sensitive CHO-K1 cells and adipocytes. Two extracts prepared from purslane (Portulaca oleracea) and tindora (Coccinia grandis) were found to induce GLUT4 translocation, accompanied by an increase of intracellular glucose concentrations. Our results indicate that the PI3K pathway is mainly responsible for the respective translocation process. Atomic force microscopy was used to prove complete plasma membrane insertion. Furthermore, this approach suggested a compound mediated distribution of GLUT4 molecules in the plasma membrane similar to insulin stimulated conditions. Utilizing a fluorescent actin marker, TIRF measurements indicated an impact of purslane and tindora on actin remodeling as observed in insulin treated cells. Finally, in-ovo experiments suggested a significant reduction of blood glucose levels under tindora and purslane treated conditions in a living organism. In conclusion, this study confirms the anti-diabetic properties of tindora and purslane, which stimulate GLUT4 translocation in an insulin-like manner. PMID:26820984

Expression and Purification of Rat Glucose Transporter 1 in Pichia pastoris.

Science.gov (United States)

Venskutonytė, Raminta; Elbing, Karin; Lindkvist-Petersson, Karin

2018-01-01

Large amounts of pure and homogenous protein are a prerequisite for several biochemical and biophysical analyses, and in particular if aiming at resolving the three-dimensional protein structure. Here we describe the production of the rat glucose transporter 1 (GLUT1), a membrane protein facilitating the transport of glucose in cells. The protein is recombinantly expressed in the yeast Pichia pastoris. It is easily maintained and large-scale protein production in shaker flasks, as commonly performed in academic research laboratories, results in relatively high yields of membrane protein. The purification protocol describes all steps needed to obtain a pure and homogenous GLUT1 protein solution, including cell growth, membrane isolation, and chromatographic purification methods.

Antenatal corticosteroids alter insulin signaling pathways in fetal baboon skeletal muscle.

Science.gov (United States)

Blanco, Cynthia L; Moreira, Alvaro G; McGill-Vargas, Lisa L; Anzueto, Diana G; Nathanielsz, Peter; Musi, Nicolas

2014-05-01

We hypothesize that prenatal exposure to glucocorticoids (GCs) negatively alters the insulin signal transduction pathway and has differing effects on the fetus according to gestational age (GA) at exposure. Twenty-three fetal baboons were delivered from 23 healthy, nondiabetic mothers. Twelve preterm (0.67 GA) and 11 near-term (0.95 GA) baboons were killed immediately after delivery. Half of the pregnant baboons at each gestation received two doses of i.m. betamethasone 24 h apart (170 μg/kg) before delivery, while the other half received no intervention. Vastus lateralis muscle was obtained from postnatal animals to measure the protein content and gene expression of insulin receptor β (IRβ; INSR), IRβ Tyr 1361 phosphorylation (pIRβ), IR substrate 1 (IRS1), IRS1 tyrosine phosphorylation (pIRS1), p85 subunit of PI3-kinase, AKT (protein kinase B), phospho-AKT Ser473 (pAKT), AKT1, AKT2, and glucose transporters (GLUT1 and GLUT4). Skeletal muscle from preterm baboons exposed to GCs had markedly reduced protein content of AKT and AKT1 (respectively, 73 and 72% from 0.67 GA control, P<0.001); IRβ and pIRβ were also decreased (respectively, 94 and 85%, P<0.01) in the muscle of premature GC-exposed fetuses but not in term fetuses. GLUT1 and GLUT4 tended to increase with GC exposure in preterm animals (P=0.09), while GLUT4 increased sixfold in term animals after exposure to GC (P<0.05). In conclusion, exposure to a single course of antenatal GCs during fetal life alters the insulin signaling pathway in fetal muscle in a manner dependent on the stage of gestation.

Arachidonic acid and lipoxinA4 attenuate streptozotocin-induced cytotoxicity to RIN5 F cells in vitro and type 1 and type 2 diabetes mellitus in vivo.

Science.gov (United States)

Gundala, Naveen K V; Naidu, Vegi G M; Das, Undurti N

2017-03-01

The aim of this study was to observe whether polyunsaturated fatty acids (PUFAs) can protect rat insulinoma (RIN5 F) cells against streptozotocin (STZ)-induced apoptosis in vitro and type 1 diabetes mellitus (T1DM) and type 2 DM (T2DM) in vivo and if so, what would be the mechanism of this action. RIN5 F cells were used for the in vitro study, whereas the in vivo study was performed in Wistar rats. STZ was used to induce apoptosis of RIN5 F cells in vitro and T1- and T2DM in vivo. The effect of PUFAs: γ-linolenic acid (GLA), arachidonic acid (AA) of ω-6 series, and eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) of ω-3 series; cyclooxygenase (COX) and lipoxygenase (LOX) inhibitors and antiinflammatory metabolite of AA and DHA, lipoxin A4 (LXA4), and resolvin D2 and protectin, respectively against STZ-induced cytotoxicity to RIN5 F cells in vitro and LXA4 against T1- and T2DM in vivo was studied. Changes in the antioxidant content, lipid peroxides, nitric oxide, and expression of PDX1, P65, nuclear factor-κb (NF-κb), and IKB genes in STZ-treated RIN5 F cells in vitro and Nrf2, GLUT2, COX2, iNOS protein levels in the pancreatic tissue of T1- and T2DM and LPCLN2 (lipocalin 2), NF-κb, IKB I in adipose tissue of T2DM after LXA4 treatment were studied. Plasma glucose, insulin, and tumor necrosis factor (TNF)-α levels also were measured in STZ-induced T1- and T2DM Wistar rats. Among all PUFAs tested, AA and EPA are the most effective against STZ-induced cytotoxicity to RIN5 F cells in vitro. Neither COX nor LOX inhibitors blocked the cytoprotective action of AA in vitro and T1- and T2DM by STZ. LXA4 production by RIN5 F cells in vitro and plasma LXA4 levels in STZ-induced T1- and T2DM animals were decreased by STZ that reverted to normal after AA treatment. AA prevented both T1- and T2DM induced by STZ. Antiinflammatory metabolite of AA and LXA4 prevented both T1- and T2DM induced by STZ. The expression of Pdx1, NF-κb, IKB genes in the

Expression Patterns and Correlations with Metabolic Markers of Zinc Transporters ZIP14 and ZNT1 in Obesity and Polycystic Ovary Syndrome

Science.gov (United States)

Maxel, Trine; Svendsen, Pernille Fog; Smidt, Kamille; Lauridsen, Jesper Krogh; Brock, Birgitte; Pedersen, Steen Bønlykke; Rungby, Jørgen; Larsen, Agnete

2017-01-01

Polycystic ovary syndrome (PCOS) is associated with infertility, increased androgen levels, and insulin resistance. In adipose tissue, zinc facilitates insulin signaling. Circulating zinc levels are altered in obesity, diabetes, and PCOS; and zinc supplementation can ameliorate metabolic disturbances in PCOS. In adipose tissue, expression of zinc influx transporter ZIP14 varies with body mass index (BMI), clinical markers of metabolic syndrome, and peroxisome proliferator-activated receptor gamma (PPARG). In this study, we investigated expression levels of ZIP14 and PPARG in subcutaneous adipose tissue of 36 PCOS women (17 lean and 19 obese women) compared with 23 healthy controls (7 lean and 16 obese women). Further, expression levels of zinc transporter ZIP9, a recently identified androgen receptor, and zinc efflux transporter ZNT1 were investigated, alongside lipid profile and markers of glucose metabolism [insulin degrading enzyme, retinol-binding protein 4 (RBP4), and glucose transporter 4 (GLUT4)]. We find that ZIP14 expression is reduced in obesity and positively correlates with PPARG expression, which is downregulated with increasing BMI. ZNT1 is upregulated in obesity, and both ZIP14 and ZNT1 expression significantly correlates with clinical markers of altered glucose metabolism. In addition, RBP4 and GLUT4 associate with obesity, but an association with PCOS as such was present only for PPARG and RBP4. ZIP14 and ZNT1 does not relate to clinical androgen status and ZIP9 is unaffected by all parameters investigated. In conclusion, our findings support the existence of a zinc dyshomeostasis in adipose tissue in metabolic disturbances including PCOS-related obesity. PMID:28303117

Scoparia dulcis (SDF7) endowed with glucose uptake properties on L6 myotubes compared insulin.

Science.gov (United States)

Beh, Joo Ee; Latip, Jalifah; Abdullah, Mohd Puad; Ismail, Amin; Hamid, Muhajir

2010-05-04

Insulin stimulates glucose uptake and promotes the translocation of glucose transporter 4 (Glut 4) to the plasma membrane on L6 myotubes. The aim of this study is to investigate affect of Scoparia dulcis Linn water extracts on glucose uptake activity and the Glut 4 translocation components (i.e., IRS-1, PI 3-kinase, PKB/Akt2, PKC and TC 10) in L6 myotubes compared to insulin. Extract from TLC fraction-7 (SDF7) was used in this study. The L6 myotubes were treated by various concentrations of SDF7 (1 to 50 microg/ml) and insulin (1 to 100 nM). The glucose uptake activities of L6 myotubes were evaluated using 2-Deoxy-D-glucose uptake assay in with or without fatty acid-induced medium. The Glut 4 translocation components in SDF7-treated L6 myotubes were detected using immunoblotting and quantified by densitometry compared to insulin. Plasma membrane lawn assay and glycogen colorimetry assay were carried out in SDF7- and insulin-treated L6 myotubes in this study. Here, our data clearly shows that SDF7 possesses glucose uptake properties on L6 myotubes that are dose-dependent, time-dependent and plasma membrane Glut 4 expression-dependent. SDF7 successfully stimulates glucose uptake activity as potent as insulin at a maximum concentration of 50 microg/ml at 480 min on L6 myotubes. Furthermore, SDF7 stimulates increased Glut 4 expression and translocation to plasma membranes at equivalent times. Even in the insulin resistance stage (free fatty acids-induced), SDF7-treated L6 myotubes were found to be more capable at glucose transport than insulin treatment. Thus, we suggested that Scoparia dulcis has the potential to be categorized as a hypoglycemic medicinal plant based on its good glucose transport properties. (c) 2010 Elsevier Ireland Ltd. All rights reserved.

Coalition of Oct4A and β1 integrins in facilitating metastasis in ovarian cancer

International Nuclear Information System (INIS)

Samardzija, Chantel; Luwor, Rodney B.; Quinn, Michael A.; Kannourakis, George; Findlay, Jock K.; Ahmed, Nuzhat

2016-01-01

Ovarian cancer is a metastatic disease and one of the leading causes of gynaecology malignancy-related deaths in women. Cancer stem cells (CSCs) are key contributors of cancer metastasis and relapse. Integrins are a family of cell surface receptors which allow interactions between cells and their surrounding microenvironment and play a fundamental role in promoting metastasis. This study investigates the molecular mechanism which associates CSCs and integrins in ovarian cancer metastasis. The expression of Oct4A in high-grade serous ovarian tumors and normal ovaries was determined by immunofluorescence analysis. The functional role of Oct4A was evaluated by generating stable knockdown (KD) of Oct4A clones in an established ovarian cancer cell line HEY using shRNA-mediated silencing. The expression of integrins in cell lines was evaluated by flow cytometry. Spheroid forming ability, adhesion and the activities of matrix metalloproteinases 9/2 (MMP-9/2) was measured by in vitro functional assays and gelatin zymography. These observations were further validated in in vivo mouse models using Balb/c nu/nu mice. We report significantly elevated expression of Oct4A in high-grade serous ovarian tumors compared to normal ovarian tissues. The expression of Oct4A in ovarian cancer cell lines correlated with their CSC-related sphere forming abilities. The suppression of Oct4A in HEY cells resulted in a significant diminution of integrin β1 expression and associated α5 and α2 subunits compared to vector control cells. This was associated with a reduced adhesive ability on collagen and fibronectin and decreased secretion of pro-MMP2 in Oct4A KD cells compared to vector control cells. In vivo, Oct4A knock down (KD) cells produced tumors which were significantly smaller in size and weight compared to tumors derived from vector control cells. Immunohistochemical analyses of Oct4A KD tumor xenografts demonstrated a significant loss of cytokeratin 7 (CK7), Glut-1 as well as CD34

Characteristics of [18F] fluorodeoxyglucose uptake in human colon cancer cells