TY - JOUR A1 - Gründemann, Dirk A1 - Gorboulev, Valentin A1 - Gambaryan, Stepan A1 - Veyhl, Maike A1 - Koepsell, Hermann T1 - Drug excretion mediated by a new prototype of polyspecific transporter N2 - CATIO~IC drugs of different types and structures (antihistaminics, antiarrhythmics, sedatives, opiates, cytostatics and antibiotics, for example) are excreted in mammals by epithelial cells of the renal proximal tubules and by hepatocytes in the liver1-4. In the proximal tubules, two functionally disparate transport systems are involved which are localized in the basolateral and luminal plasma membrane and are different from the previously identified neuronal monoamine transporters and A TP-dependent multidrug exporting proteins1-3,5-12. Here we report the isolation of a complementary DNA from rat kidney that encodes a 556-amino-acid membrane protein, OCT1, which has the functional characteristics of organic cation uptake over the basolateral membrane of renal proximal tubules and of organic cation uptake into hepatocytes. OCTl is not homologous to any other known protein and is found in kidney, liver and intestine. As OCTl translocates hydrophobic and hydrophilic organic cations of different structures, it is considered to be a new prolotype of polyspecific transporters that are important for drug elimination. KW - Biologie Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-59327 ER - TY - JOUR A1 - Carpaneto, Armando A1 - Koepsell, Hermann A1 - Bamberg, Ernst A1 - Hedrich, Rainer A1 - Geiger, Dietmar T1 - Sucrose- and H+-Dependent Charge Movements Associated with the Gating of Sucrose Transporter ZmSUT1 N2 - Background: In contrast to man the majority of higher plants use sucrose as mobile carbohydrate. Accordingly protondriven sucrose transporters are crucial for cell-to-cell and long-distance distribution within the plant body. Generally very negative plant membrane potentials and the ability to accumulate sucrose quantities of more than 1 M document that plants must have evolved transporters with unique structural and functional features. Methodology/Principal Findings: To unravel the functional properties of one specific high capacity plasma membrane sucrose transporter in detail, we expressed the sucrose/H+ co-transporter from maize ZmSUT1 in Xenopus oocytes. Application of sucrose in an acidic pH environment elicited inward proton currents. Interestingly the sucrose-dependent H+ transport was associated with a decrease in membrane capacitance (Cm). In addition to sucrose Cm was modulated by the membrane potential and external protons. In order to explore the molecular mechanism underlying these Cm changes, presteady-state currents (Ipre) of ZmSUT1 transport were analyzed. Decay of Ipre could be best fitted by double exponentials. When plotted against the voltage the charge Q, associated to Ipre, was dependent on sucrose and protons. The mathematical derivative of the charge Q versus voltage was well in line with the observed Cm changes. Based on these parameters a turnover rate of 500 molecules sucrose/s was calculated. In contrast to gating currents of voltage dependentpotassium channels the analysis of ZmSUT1-derived presteady-state currents in the absence of sucrose (I =Q/t) was sufficient to predict ZmSUT1 transport-associated currents. Conclusions: Taken together our results indicate that in the absence of sucrose, ‘trapped’ protons move back and forth between an outer and an inner site within the transmembrane domains of ZmSUT1. This movement of protons in the electric field of the membrane gives rise to the presteady-state currents and in turn to Cm changes. Upon application of external sucrose, protons can pass the membrane turning presteady-state into transport currents. KW - Sucrose Y1 - 2010 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-68538 ER - TY - JOUR A1 - Neuhaus, Winfried A1 - Burek, Malgorzata A1 - Djuzenova, Cholpon C A1 - Thal, Serge C A1 - Koepsell, Hermann A1 - Roewer, Norbert A1 - Förster, Carola Y T1 - Addition of NMDA-receptor antagonist MK801 during oxygen/glucose deprivation moderately attenuates the up-regulation of glucose uptake after subsequent reoxygenation in brain endothelial cells N2 - During stroke the blood–brain barrier (BBB) is damaged which can result in vasogenic brain edema and inflammation. The reduced blood supply leads to decreased delivery of oxygen and glucose to affected areas of the brain. Oxygen and glucose deprivation (OGD) can cause upregulation of glucose uptake of brain endothelial cells. In this letter, we investigated the influence of MK801, a non-competitive inhibitor of the NMDA-receptor, on the regulation of the glucose uptake and of the main glucose transporters glut1 and sglt1 in murine BBB cell line cerebEND during OGD. mRNA expression of glut1 was upregulated 68.7- fold after 6 h OGD, which was significantly reduced by 10 μM MK801 to 28.9-fold. Sglt1 mRNA expression decreased during OGD which was further reduced by MK801. Glucose uptake was significantly increased up to 907% after 6 h OGD and was still higher (210%) after the 20 h reoxygenation phase compared to normoxia. Ten micromolar MK801 during OGD was able to reduce upregulated glucose uptake after OGD and reoxygenation significantly. Presence of several NMDAR subunits was proven on the mRNA level in cerebEND cells. Furthermore, it was shown that NMDAR subunit NR1 was upregulated during OGD and that this was inhibitable by MK801. In conclusion, the addition of MK801 during the OGD phase reduced significantly the glucose uptake after the subsequent reoxygenation phase in brain endothelial cells. KW - Blut-Hirn-Schranke KW - Schlaganfall KW - Glucosetransportproteine KW - NMDA-Antagonist KW - NMDA-Rezeptor KW - blood-brain barrier KW - MK801 KW - NMDAR KW - stroke KW - glut1 KW - sglt1 Y1 - 2012 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-67241 ER - TY - JOUR A1 - Jaschke, Alexander A1 - Chung, Bomee A1 - Hesse, Deike A1 - Kluge, Reinhart A1 - Zahn, Claudia A1 - Moser, Markus A1 - Petzke, Klaus-Jürgen A1 - Brigelius-Flohé, Regina A1 - Puchkov, Dmytro A1 - Koepsell, Hermann A1 - Heeren, Joerg A1 - Joost, Hans-Georg A1 - Schürmann, Annette T1 - The GTPase ARFRP1 controls the lipidation of chylomicrons in the Golgi of the intestinal epithelium JF - Human Molecular Genetics N2 - The uptake and processing of dietary lipids by the small intestine is a multistep process that involves several steps including vesicular and protein transport. The GTPase ADP-ribosylation factor-related protein 1 (ARFRP1) controls the ARF-like 1 (ARL1)-mediated Golgi recruitment of GRIP domain proteins which in turn bind several Rab-GTPases. Here, we describe the essential role of ARFRP1 and its interaction with Rab2 in the assembly and lipidation of chylomicrons in the intestinal epithelium. Mice lacking Arfrp1 specifically in the intestine \((Arfrp1^{vil−/−})\) exhibit an early post-natal growth retardation with reduced plasma triacylglycerol and free fatty acid concentrations. \(Arfrp1^{vil−/−}\) enterocytes as well as Arfrp1 mRNA depleted Caco-2 cells absorbed fatty acids normally but secreted chylomicrons with a markedly reduced triacylglycerol content. In addition, the release of apolipoprotein A-I (ApoA-I) was dramatically decreased, and ApoA-I accumulated in the \(Arfrp1^{vil−/−}\) epithelium, where it predominantly co-localized with Rab2. The release of chylomicrons from Caco-2 was markedly reduced after the suppression of Rab2, ARL1 and Golgin-245. Thus, the GTPase ARFRP1 and its downstream proteins are required for the lipidation of chylo­microns and the assembly of ApoA-I to these particles in the Golgi of intestinal epithelial cells. KW - ARF Y1 - 2012 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-125658 VL - 21 IS - 14 ER - TY - JOUR A1 - Cardani, Diego A1 - Sardi, Claudia A1 - La Ferla, Barbara A1 - D'Orazio, Guiseppe A1 - Sommariva, Michele A1 - Marcucci, Fabrizio A1 - Olivero, Daniela A1 - Tagliabue, Elda A1 - Koepsell, Hermann A1 - Nicotra, Francesco A1 - Balsari, Andrea A1 - Rumio, Christiano T1 - Sodium glucose cotransporter 1 ligand BLF501 as a novel tool for management of gastrointestinal mucositis JF - Molecular Cancer N2 - Background: Recent studies demonstrated that engagement of sodium glucose transporter 1 (SGLT-1) by orally administered D-glucose protects the intestinal mucosa from lipopolysaccharide (LPS)-induced injury. We tested whether SGLT-1 engagement might protect the intestinal mucosa from doxorubicin (DXR)- and 5-fluorouracil (5-FU)-induced injury in animal models mimicking acute or chronic mucositis. Methods: Mice were treated intraperitoneally with DXR, alone or in combination with 5-FU, and orally with BLF501, a glucose-derived synthetic compound with high affinity for SGLT-1. Intestinal mucosal epithelium integrity was assessed by histological analysis, cellular proliferation assays, real-time PCR gene expression assays and Western blot assays. Student's t-test (paired two-tailed) and X-2 analyses were used for comparisons between groups. Differences were considered significant at p < 0.05. Results: BLF501 administration in mice treated with DXR and/or 5-FU decreased the injuries to the mucosa in terms of epithelial integrity and cellular proliferative ability. Co-treatment with BLF501 led to a normal expression and distribution of both zonula occludens-1 (ZO-1) and beta-catenin, which were underexpressed after treatment with either chemotherapeutic agent alone. BLF501 administration also restored normal expression of caspase-3 and ezrin/radixin/moesin (ERM), which were overexpressed after treatment with DXR and 5-FU. In SGLT1-/- mice, BLF501 had no detectable effects. BLF501 administration in wild-type mice with growing A431 tumors did not modify antitumor activity of DXR. Conclusions: BLF501-induced protection of the intestinal mucosa is a promising novel therapeutic approach to reducing the severity of chemotherapy-induced mucositis. KW - apoptosis KW - prevention KW - doxorubicin KW - cancer KW - gastrointestinal mucositis KW - SGLT-1 KW - synthetic D-glucose analogy KW - chemotherapy KW - inflammation KW - clinical practice guidelines KW - intestinal mucositis KW - epithelial cells KW - oral mucositis KW - gene-expression Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-117352 SN - 1476-4598 VL - 13 IS - 23 ER - TY - JOUR A1 - Röder, Pia V. A1 - Geillinger, Kerstin E. A1 - Zietek, Tamara S. A1 - Thorens, Bernard A1 - Koepsell, Hermann A1 - Daniel, Hannelore T1 - The Role of SGLT1 and GLUT2 in Intestinal Glucose Transport and Sensing JF - PLOS ONE N2 - Intestinal glucose absorption is mediated by SGLT1 whereas GLUT2 is considered to provide basolateral exit. Recently, it was proposed that GLUT2 can be recruited into the apical membrane after a high luminal glucose bolus allowing bulk absorption of glucose by facilitated diffusion. Moreover, SGLT1 and GLUT2 are suggested to play an important role in intestinal glucose sensing and incretin secretion. In mice that lack either SGLT1 or GLUT2 we re-assessed the role of these transporters in intestinal glucose uptake after radiotracer glucose gavage and performed Western blot analysis for transporter abundance in apical membrane fractions in a comparative approach. Moreover, we examined the contribution of these transporters to glucose-induced changes in plasma GIP, GLP-1 and insulin levels. In mice lacking SGLT1, tissue retention of tracer glucose was drastically reduced throughout the entire small intestine whereas GLUT2-deficient animals exhibited higher tracer contents in tissue samples than wild type animals. Deletion of SGLT1 resulted also in reduced blood glucose elevations and abolished GIP and GLP-1 secretion in response to glucose. In mice lacking GLUT2, glucose-induced insulin but not incretin secretion was impaired. Western blot analysis revealed unchanged protein levels of SGLT1 after glucose gavage. GLUT2 detected in apical membrane fractions mainly resulted from contamination with basolateral membranes but did not change in density after glucose administration. SGLT1 is unequivocally the prime intestinal glucose transporter even at high luminal glucose concentrations. Moreover, SGLT1 mediates glucose-induced incretin secretion. Our studies do not provide evidence for GLUT2 playing any role in either apical glucose influx or incretin secretion. KW - rat small-intestine KW - brush border membrane KW - apical GLUT2 KW - incretin secretion KW - diffusive component KW - sugar absorption KW - mice KW - calcium absorption KW - phosphorylation KW - cotransporter Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-117262 VL - 9 IS - 2 ER - TY - JOUR A1 - Jurowich, Christian Ferdinand A1 - Otto, Christoph A1 - Rikkala, Prashanth Reddy A1 - Wagner, Nicole A1 - Vrhovac, Ivana A1 - Sabolić, Ivan A1 - Germer, Christoph-Thomas A1 - Koepsell, Hermann T1 - Ileal interposition in rats with experimental type 2 like diabetes improves glycemic control independently of glucose absorption JF - Journal of Diabetes Research N2 - Bariatric operations in obese patients with type 2 diabetes often improve diabetes before weight loss is observed. In patients mainly Roux-en-Y-gastric bypass with partial stomach resection is performed. Duodenojejunal bypass (DJB) and ileal interposition (IIP) are employed in animal experiments. Due to increased glucose exposition of L-cells located in distal ileum, all bariatric surgery procedures lead to higher secretion of antidiabetic glucagon like peptide-1 (GLP-1) after glucose gavage. After DJB also downregulation of Na\(^{+}\)-D-glucose cotransporter SGLT1 was observed. This suggested a direct contribution of decreased glucose absorption to the antidiabetic effect of bariatric surgery. To investigate whether glucose absorption is also decreased after IIP, we induced diabetes with decreased glucose tolerance and insulin sensitivity in male rats and investigated effects of IIP on diabetes and SGLT1. After IIP, we observed weight-independent improvement of glucose tolerance, increased insulin sensitivity, and increased plasma GLP-1 after glucose gavage. The interposed ileum was increased in diameter and showed increased length of villi, hyperplasia of the epithelial layer, and increased number of L-cells. The amount of SGLT1-mediated glucose uptake in interposed ileum was increased 2-fold reaching the same level as in jejunum. Thus, improvement of glycemic control by bariatric surgery does not require decreased glucose absorption. KW - glucagon like peptide-1 KW - food intake KW - body weight KW - cotransporter SGLT1 KW - bariatric surgery KW - biliopancreatic diversion KW - intestinal glucose KW - gut hormones KW - duodenal jejunal bypass KW - Y-gastric bypass Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-149166 VL - 2015 IS - 490365 ER - TY - JOUR A1 - Arimany-Nardi, Cristina A1 - Minuesa, Gerard A1 - Pastor-Anglada, Marçal A1 - Keller, Thorsten A1 - Erkizia, Itziar A1 - Koepsell, Hermann A1 - Martinez-Picado, Javier T1 - Role of Human Organic Cation Transporter 1 (hOCT1) Polymorphisms in Lamivudine (3TC) Uptake and Drug-Drug Interactions JF - Frontiers in Pharmacology N2 - Lamivudine (3TC), a drug used in the treatment of HIV infection, needs to cross the plasma membrane to exert its therapeutic action. Human Organic cation transporter 1 (hOCT1), encoded by the SLC22A1 gene, is the transporter responsible for its uptake into target cells. As SLC22A1 is a highly polymorphic gene, the aim of this study was to determine how SNPs in the OCT1-encoding gene affected 3TC internalization and its interaction with other co-administered drugs. HEK293 cells stably transfected with either the wild type form or the polymorphic variants of hOCT1 were used to perform kinetic and drug-drug interaction studies. Protein co-immunoprecipitation was used to assess the impact of selected polymorphic cysteines on the oligomerization of the transporter. Results showed that 3TC transport efficiency was reduced in all polymorphic variants tested (R61C, C88R, S189L, M420del, and G465R). This was not caused by lack of oligomerization in case of variants located at the transporter extracellular loop (R61C and C88R). Drug-drug interaction measurements showed that co-administered drugs [abacavir (ABC), zidovudine (AZT), emtricitabine (FTC), tenofovir diproxil fumarate (TDF), efavirenz (EFV) and raltegravir (RAL)], differently inhibited 3TC uptake depending upon the polymorphic variant analyzed. These data highlight the need for accurate analysis of drug transporter polymorphic variants of clinical relevance, because polymorphisms can impact on substrate (3TC) translocation but even more importantly they can differentially affect drug-drug interactions at the transporter level. KW - hOCT1 KW - pharmacogenetics KW - lamivudine KW - HIV infection KW - therapy Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-165236 VL - 7 IS - 175 ER - TY - JOUR A1 - Bhavsar, Shefalee K. A1 - Singh, Yogesh A1 - Sharma, Piyush A1 - Khairnar, Vishal A1 - Hosseinzadeh, Zohreh A1 - Zhang, Shaqiu A1 - Palmada, Monica A1 - Sabolic, Ivan A1 - Koepsell, Hermann A1 - Lang, Karl S. A1 - Lang, Philipp A. A1 - Lang, Florian T1 - Expression of JAK3 Sensitive Na\(^+\) Coupled Glucose Carrier SGLT1 in Activated Cytotoxic T Lymphocytes JF - Cellular Physiology and Biochemistry N2 - Background: Similar to tumor cells, activated T-lymphocytes generate ATP mainly by glycolytic degradation of glucose. Lymphocyte glucose uptake involves non-concentrative glucose carriers of the GLUT family. In contrast to GLUT isoforms, Na+-coupled glucose-carrier SGLT1 accumulates glucose against glucose gradients and is effective at low extracellular glucose concentrations. The present study explored expression and regulation of SGLT1 in activated murine splenic cytotoxic T cells (CTLs) and human Jurkat T cells. Methods: FACS analysis, immunofluorescence, confocal microscopy, chemiluminescence and Western blotting were employed to estimate SGLT1 expression, function and regulation in lymphocytes, as well as dual electrode voltage clamp in SGLT1 ± JAK3 expressing Xenopus oocytes to quantify the effect of janus kinase3 (JAK3) on SGLT1 function. Results: SGLT1 is expressed in murine CTLs and also in human Jurkat T cells. 2-(N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino)-2-deoxyglucose uptake was significantly decreased by SGLT1-blocker phloridzin (0.2 mM) and by pharmacological inhibition of JAK3 with WHI-P131 (156 µM), WHI-P154 (11.2 µM) and JAK3 inhibitor VI (0.5 µM). Electrogenic glucose transport (Iglucose) in Xenopus oocytes expressing human SGLT1 was increased by additional expression of human wild type JAK3, active A568VJAK3 but not inactive K851AJAK3. Coexpression of JAK3 enhanced the maximal transport rate without significantly modifying affinity of the carrier. Iglucose in SGLT1+JAK3 expressing oocytes was significantly decreased by WHI-P154 (11.2 µM). JAK3 increased the SGLT1 protein abundance in the cell membrane. Inhibition of carrier insertion by brefeldin A (5 µM) in SGLT1+JAK3 expressing oocytes resulted in a decline of Iglucose, which was similar in presence and absence of JAK3. Conclusions: SGLT1 is expressed in murine cytotoxic T cells and human Jurkat T cells and significantly contributes to glucose uptake in those cells post activation. JAK3 up-regulates SGLT1 activity by increasing the carrier protein abundance in the cell membrane, an effect enforcing cellular glucose uptake into activated lymphocytes and thus contributing to the immune response. KW - tumor cell KW - Cytotoxic T lymphocytes KW - Glucose uptake KW - Jurkat T cells KW - Energy depletion KW - Janus kinase Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-164900 VL - 39 IS - 3 ER - TY - JOUR A1 - Shepard, Blythe D. A1 - Cheval, Lydie A1 - Peterlin, Zita A1 - Firestein, Stuart A1 - Koepsell, Hermann A1 - Doucet, Alain A1 - Pluznick, Jennifer L. T1 - A Renal Olfactory Receptor Aids in Kidney Glucose Handling JF - Scientific Reports N2 - Olfactory receptors (ORs) are G protein-coupled receptors which serve important sensory functions beyond their role as odorant detectors in the olfactory epithelium. Here we describe a novel role for one of these ORs, Olfr1393, as a regulator of renal glucose handling. Olfr1393 is specifically expressed in the kidney proximal tubule, which is the site of renal glucose reabsorption. Olfr1393 knockout mice exhibit urinary glucose wasting and improved glucose tolerance, despite euglycemia and normal insulin levels. Consistent with this phenotype, Olfr1393 knockout mice have a significant decrease in luminal expression of Sglt1, a key renal glucose transporter, uncovering a novel regulatory pathway involving Olfr1393 and Sglt1. In addition, by utilizing a large scale screen of over 1400 chemicals we reveal the ligand profile of Olfr1393 for the first time, offering new insight into potential pathways of physiological regulation for this novel signaling pathway. KW - olfactory receptor KW - Olfr1393 KW - kidney KW - glucose handling Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-167605 VL - 6 IS - 35215 ER - TY - JOUR A1 - Gallo, Linda A. A1 - Ward, Micheal S. A1 - Fotheringham, Amelia K. A1 - Zhuang, Aowen A1 - Borg, Danielle J. A1 - Flemming, Nicole B. A1 - Harvie, Ben M. A1 - Kinneally, Toni L. A1 - Yeh, Shang-Ming A1 - McCarthy, Domenica A. A1 - Koepsell, Hermann A1 - Vallon, Volker A1 - Pollock, Carol A1 - Panchapakesan, Usha A1 - Forbes, Josephine M. T1 - Once daily administration of the SGLT2 inhibitor, empagliflozin, attenuates markers of renal fibrosis without improving albuminuria in diabetic db/db mice JF - Scientific Reports N2 - Blood glucose control is the primary strategy to prevent complications in diabetes. At the onset of kidney disease, therapies that inhibit components of the renin angiotensin system (RAS) are also indicated, but these approaches are not wholly effective. Here, we show that once daily administration of the novel glucose lowering agent, empagliflozin, an SGLT2 inhibitor which targets the kidney to block glucose reabsorption, has the potential to improve kidney disease in type 2 diabetes. In male db/db mice, a 10-week treatment with empagliflozin attenuated the diabetes-induced upregulation of profibrotic gene markers, fibronectin and transforming-growth-factor-beta. Other molecular (collagen IV and connective tissue growth factor) and histological (tubulointerstitial total collagen and glomerular collagen IV accumulation) benefits were seen upon dual therapy with metformin. Albuminuria, urinary markers of tubule damage (kidney injury molecule-1, KIM-1 and neutrophil gelatinase-associated lipocalin, NGAL), kidney growth, and glomerulosclerosis, however, were not improved with empagliflozin or metformin, and plasma and intra-renal renin activity was enhanced with empagliflozin. In this model, blood glucose lowering with empagliflozin attenuated some molecular and histological markers of fibrosis but, as per treatment with metformin, did not provide complete renoprotection. Further research to refine the treatment regimen in type 2 diabetes and nephropathy is warranted. KW - SGLT2 inhibitor KW - empagliflozin KW - glucose lowering agent KW - kidney disease KW - type 2 diabetes Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-167678 VL - 6 IS - 26428 ER - TY - JOUR A1 - Salker, Madhuri S. A1 - Singh, Yogesh A1 - Zeng, Ni A1 - Chen, Hong A1 - Zhang, Shaqiu A1 - Umbach, Anja T. A1 - Fakhri, Hajar A1 - Kohlhofer, Ursula A1 - Quintanilla-Martinez, Leticia A1 - Durairaj, Ruban R. Peter A1 - Barros, Flavio S. V. A1 - Vrljicak, Pavle A1 - Ott, Sascha A1 - Brucker, Sara Y. A1 - Wallwiener, Diethelm A1 - Madunić, Ivana Vrhovac A1 - Breljak, Davorka A1 - Sabolić, Ivan A1 - Koepsell, Hermann A1 - Brosens, Jan J. A1 - Lang, Florian T1 - Loss of endometrial sodium glucose cotransporter SGLT1 is detrimental to embryo survival and fetal growth in pregnancy JF - Scientific Reports N2 - Embryo implantation requires a hospitable uterine environment. A key metabolic change that occurs during the peri-implantation period, and throughout early pregnancy, is the rise in endometrial glycogen content. Glycogen accumulation requires prior cellular uptake of glucose. Here we show that both human and murine endometrial epithelial cells express the high affinity Na\(^+\)-coupled glucose carrier SGLT1. Ussing chamber experiments revealed electrogenic glucose transport across the endometrium in wild type (\(Slc5a1^{+/+}\)) but not in SGLT1 defcient (\(Slc5a1^{−/−}\)) mice. Endometrial glycogen content, litter size and weight of offspring at birth were signifcantly lower in \(Slc5a1^{−/−}\) mice. In humans, \(SLC5A1\) expression was upregulated upon decidualization of primary endometrial stromal cells. Endometrial \(SLC5A1\) expression during the implantation window was attenuated in patients with recurrent pregnancy loss when compared with control subjects. Our fndings reveal a novel mechanism establishing adequate endometrial glycogen stores for pregnancy. Disruption of this histiotrophic pathway leads to adverse pregnancy outcome. KW - biology KW - embryology KW - intrauterine growth KW - paediatric research Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-173814 VL - 7 ER - TY - JOUR A1 - Van Steenbergen, Anne A1 - Balteau, Magali A1 - Ginion, Audrey A1 - Ferté, Laura A1 - Battault, Sylvain A1 - de Meester de Ravenstein, Christophe A1 - Balligand, Jean-Luc A1 - Daskalopoulos, Evangelos-Panagiotis A1 - Gilon, Patrick A1 - Despa, Florin A1 - Despa, Sanda A1 - Vanoverschelde, Jean-Louis A1 - Horman, Sandrine A1 - Koepsell, Hermann A1 - Berry, Gerard A1 - Hue, Louis A1 - Bertrand, Luc A1 - Beauloye, Christophe T1 - Sodium-myoinositol cotransporter-1, SMIT1, mediates the production of reactive oxygen species induced by hyperglycemia in the heart JF - Scientific Reports N2 - Hyperglycemia (HG) stimulates the production of reactive oxygen species in the heart through activation of NADPH oxidase 2 (NOX2). This production is independent of glucose metabolism but requires sodium/glucose cotransporters (SGLT). Seven SGLT isoforms (SGLT1 to 6 and sodium-myoinositol cotransporter-1, SMIT1) are known, although their expression and function in the heart remain elusive. We investigated these 7 isoforms and found that only SGLT1 and SMIT1 were expressed in mouse, rat and human hearts. In cardiomyocytes, galactose (transported through SGLT1) did not activate NOX2. Accordingly, SGLT1 deficiency did not prevent HG-induced NOX2 activation, ruling it out in the cellular response to HG. In contrast, myo-inositol (transported through SMIT1) reproduced the toxic effects of HG. SMIT1 overexpression exacerbated glucotoxicity and sensitized cardiomyocytes to HG, whereas its deletion prevented HG-induced NOX2 activation. In conclusion, our results show that heart SMIT1 senses HG and triggers NOX2 activation. This could participate in the redox signaling in hyperglycemic heart and contribute to the pathophysiology of diabetic cardiomyopathy. KW - hyperglycemia KW - Sodium-myoinositol cotransporter-1 (SMIT1) KW - glucose metabolism KW - heart KW - NADPH oxidase 2 (NOX2) KW - sodium/glucose cotransporters (SGLT) KW - cardiomyocytes Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-180891 VL - 7 ER - TY - JOUR A1 - Schäfer, Nadine A1 - Friedrich, Maximilian A1 - Jørgensen, Morten Egevang A1 - Kollert, Sina A1 - Koepsell, Hermann A1 - Wischmeyer, Erhard A1 - Lesch, Klaus-Peter A1 - Geiger, Dietmar A1 - Döring, Frank T1 - Functional analysis of a triplet deletion in the gene encoding the sodium glucose transporter 3, a potential risk factor for ADHD JF - PLoS ONE N2 - Sodium-glucose transporters (SGLT) belong to the solute carrier 5 family, which is characterized by sodium dependent transport of sugars and other solutes. In contrast, the human SGLT3 (hSGLT3) isoform, encoded by SLC5A4, acts as a glucose sensor that does not transport sugar but induces membrane depolarization by Na\(^{+}\) currents upon ligand binding. Whole-exome sequencing (WES) of several extended pedigrees with high density of attention-deficit/hyperactivity disorder (ADHD) identified a triplet ATG deletion in SLC5A4 leading to a single amino acid loss (ΔM500) in the hSGLT3 protein imperfectly co-segregating with the clinical phenotype of ADHD. Since mutations in homologous domains of hSGLT1 and hSGLT2 were found to affect intestinal and renal function, respectively, we analyzed the functional properties of hSGLT3[wt] and [ΔM500] by voltage clamp and current clamp recordings from cRNA-injected Xenopus laevis oocytes. The cation conductance of hSGLT3[wt] was activated by application of glucose or the specific agonist 1-desoxynojirimycin (DNJ) as revealed by inward currents in the voltage clamp configuration and cell depolarization in the current clamp mode. Almost no currents and changes in membrane potential were observed when glucose or DNJ were applied to hSGLT3[ΔM500]-injected oocytes, demonstrating a loss of function by this amino acid deletion in hSGLT3. To monitor membrane targeting of wt and mutant hSGLT3, fusion constructs with YFP were generated, heterologously expressed in Xenopus laevis oocytes and analyzed for membrane fluorescence by confocal microscopy. In comparison to hSGLT3[wt] the fluorescent signal of mutant [ΔM500] was reduced by 43% indicating that the mutant phenotype might mainly result from inaccurate membrane targeting. As revealed by homology modeling, residue M500 is located in TM11 suggesting that in addition to the core structure (TM1-TM10) of the transporter, the surrounding TMs are equally crucial for transport/sensor function. In conclusion, our findings indicate that the deletion [ΔM500] in hSGLT3 inhibits membrane targeting and thus largely disrupts glucose-induced sodium conductance, which may, in interaction with other ADHD risk-related gene variants, influence the risk for ADHD in deletion carriers. KW - Xenopus laevis oocytes KW - ADHD KW - glucose KW - cell membranes KW - membrane proteins KW - membrane potential KW - crystal structure KW - amino acid analysis Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-176495 VL - 13 IS - 10 ER - TY - JOUR A1 - Otto, Christoph A1 - Friedrich, Alexandra A1 - Madunić, Ivana Vrhovac A1 - Baumeier, Christian A1 - Schwenk, Robert W. A1 - Karaica, Dean A1 - Germer, Christoph-Thomas A1 - Schürmann, Annette A1 - Sabolić, Ivan A1 - Koepsell, Hermann, Hermann T1 - Antidiabetic Effects of a Tripeptide That Decreases Abundance of Na\(^+\)-D-glucose Cotransporter SGLT1 in the Brush-Border Membrane of the Small Intestine JF - ACS Omega N2 - In enterocytes, protein RS1 (RSC1A1) mediates an increase of glucose absorption after ingestion of glucose-rich food via upregulation of Na+-D-glucose cotransporter SGLT1 in the brush-border membrane (BBM). Whereas RS1 decelerates the exocytotic pathway of vesicles containing SGLT1 at low glucose levels between meals, RS1-mediated deceleration is relieved after ingestion of glucose-rich food. Regulation of SGLT1 is mediated by RS1 domain RS1-Reg, in which Gln-Ser-Pro (QSP) is effective. In contrast to QSP and RS1-Reg, Gln-Glu-Pro (QEP) and RS1-Reg with a serine to glutamate exchange in the QSP motif downregulate the abundance of SGLT1 in the BBM at high intracellular glucose concentrations by about 50%. We investigated whether oral application of QEP improves diabetes in db/db mice and affects the induction of diabetes in New Zealand obese (NZO) mice under glucolipotoxic conditions. After 6-day administration of drinking water containing 5 mM QEP to db/db mice, fasting glucose was decreased, increase of blood glucose in the oral glucose tolerance test was blunted, and insulin sensitivity was increased. When QEP was added for several days to a high fat/high carbohydrate diet that induced diabetes in NZO mice, the increase of random plasma glucose was prevented, accompanied by lower plasma insulin levels. QEP is considered a lead compound for development of new antidiabetic drugs with more rapid cellular uptake. In contrast to SGLT1 inhibitors, QEP-based drugs may be applied in combination with insulin for the treatment of type 1 and type 2 diabetes, decreasing the required insulin amount, and thereby may reduce the risk of hypoglycemia. KW - chemistry Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-230654 N1 - Lizenz: https://pubs.acs.org/page/policy/authorchoice_termsofuse.html VL - 5 IS - 45 ER - TY - JOUR A1 - Koepsell, Hermann T1 - Glucose transporters in the small intestine in health and disease JF - Pflügers Archiv - European Journal of Physiology N2 - Absorption of monosaccharides is mainly mediated by Na\(^+\)-d-glucose cotransporter SGLT1 and the facititative transporters GLUT2 and GLUT5. SGLT1 and GLUT2 are relevant for absorption of d-glucose and d-galactose while GLUT5 is relevant for d-fructose absorption. SGLT1 and GLUT5 are constantly localized in the brush border membrane (BBM) of enterocytes, whereas GLUT2 is localized in the basolateral membrane (BLM) or the BBM plus BLM at low and high luminal d-glucose concentrations, respectively. At high luminal d-glucose, the abundance SGLT1 in the BBM is increased. Hence, d-glucose absorption at low luminal glucose is mediated via SGLT1 in the BBM and GLUT2 in the BLM whereas high-capacity d-glucose absorption at high luminal glucose is mediated by SGLT1 plus GLUT2 in the BBM and GLUT2 in the BLM. The review describes functions and regulations of SGLT1, GLUT2, and GLUT5 in the small intestine including diurnal variations and carbohydrate-dependent regulations. Also, the roles of SGLT1 and GLUT2 for secretion of enterohormones are discussed. Furthermore, diseases are described that are caused by malfunctions of small intestinal monosaccharide transporters, such as glucose-galactose malabsorption, Fanconi syndrome, and fructose intolerance. Moreover, it is reported how diabetes, small intestinal inflammation, parental nutrition, bariatric surgery, and metformin treatment affect expression of monosaccharide transporters in the small intestine. Finally, food components that decrease d-glucose absorption and drugs in development that inhibit or downregulate SGLT1 in the small intestine are compiled. Models for regulations and combined functions of glucose transporters, and for interplay between d-fructose transport and metabolism, are discussed. KW - glucose transporter KW - small intestine KW - regulation KW - SGLT1 KW - GLUT2 KW - GLUT5 KW - glucose-galactose malabsorption KW - fructose intolerance KW - diabetes KW - bariatric surgery Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-232552 SN - 0031-6768 VL - 472 ER - TY - JOUR A1 - Koepsell, Hermann T1 - Glucose transporters in brain in health and disease JF - Pflügers Archiv - European Journal of Physiology N2 - Energy demand of neurons in brain that is covered by glucose supply from the blood is ensured by glucose transporters incapillaries and brain cells. In brain, the facilitative diffusion glucose transporters GLUT1-6 and GLUT8, and the Na+-D-glucosecotransporters SGLT1 are expressed. The glucose transporters mediate uptake of D-glucose across the blood-brain barrier anddelivery of D-glucose to astrocytes and neurons. They are critically involved in regulatory adaptations to varying energy demandsin response to differing neuronal activities and glucose supply. In this review, a comprehensive overview about verified andproposed roles of cerebral glucose transporters during health and diseases is presented. Our current knowledge is mainly based onexperiments performed in rodents. First, the functional properties of human glucose transporters expressed in brain and theircerebral locations are described. Thereafter, proposed physiological functions of GLUT1, GLUT2, GLUT3, GLUT4, andSGLT1 for energy supply to neurons, glucose sensing, central regulation of glucohomeostasis, and feeding behavior are compiled, and their roles in learning and memory formation are discussed. In addition, diseases are described in which functionalchanges of cerebral glucose transporters are relevant. These are GLUT1 deficiency syndrome (GLUT1-SD), diabetes mellitus, Alzheimer’s disease (AD), stroke, and traumatic brain injury (TBI). GLUT1-SD is caused by defect mutations in GLUT1. Diabetes and AD are associated with changed expression of glucose transporters in brain, and transporter-related energy defi-ciency of neurons may contribute to pathogenesis of AD. Stroke and TBI are associated with changes of glucose transporter expression that influence clinical outcome KW - glucosetransporter KW - brain KW - GLUT1 KW - GLUT2 KW - GLUT3 KW - GLUT4 KW - SGLT1 KW - diabetes KW - Parkinson’s disease KW - stroke Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-232746 SN - 0031-6768 VL - 472 ER -