@article{ArimanyNardiMinuesaPastorAngladaetal.2016,
author = {Arimany-Nardi, Cristina and Minuesa, Gerard and Pastor-Anglada, Mar{\c{c}}al and Keller, Thorsten and Erkizia, Itziar and Koepsell, Hermann and Martinez-Picado, Javier},
title = {Role of Human Organic Cation Transporter 1 (hOCT1) Polymorphisms in Lamivudine (3TC) Uptake and Drug-Drug Interactions},
series = {Frontiers in Pharmacology},
volume = {7},
journal = {Frontiers in Pharmacology},
number = {175},
doi = {10.3389/fphar.2016.00175},
url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-165236},
year = {2016},
abstract = {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.},
language = {en}
}
@article{JurowichOttoRikkalaetal.2015,
author = {Jurowich, Christian Ferdinand and Otto, Christoph and Rikkala, Prashanth Reddy and Wagner, Nicole and Vrhovac, Ivana and Sabolić, Ivan and Germer, Christoph-Thomas and Koepsell, Hermann},
title = {Ileal interposition in rats with experimental type 2 like diabetes improves glycemic control independently of glucose absorption},
series = {Journal of Diabetes Research},
volume = {2015},
journal = {Journal of Diabetes Research},
number = {490365},
doi = {10.1155/2015/490365},
url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-149166},
year = {2015},
abstract = {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.},
language = {en}
}
@article{NeuhausBurekDjuzenovaetal.2012,
author = {Neuhaus, Winfried and Burek, Malgorzata and Djuzenova, Cholpon C and Thal, Serge C and Koepsell, Hermann and Roewer, Norbert and F{\"o}rster, Carola Y},
title = {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},
url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-67241},
year = {2012},
abstract = {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.},
subject = {Blut-Hirn-Schranke},
language = {en}
}
@article{CarpanetoKoepsellBambergetal.2010,
author = {Carpaneto, Armando and Koepsell, Hermann and Bamberg, Ernst and Hedrich, Rainer and Geiger, Dietmar},
title = {Sucrose- and H+-Dependent Charge Movements Associated with the Gating of Sucrose Transporter ZmSUT1},
url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-68538},
year = {2010},
abstract = {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.},
language = {en}
}
@article{GruendemannGorboulevGambaryanetal.1994,
author = {Gr{\"u}ndemann, Dirk and Gorboulev, Valentin and Gambaryan, Stepan and Veyhl, Maike and Koepsell, Hermann},
title = {Drug excretion mediated by a new prototype of polyspecific transporter},
url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-59327},
year = {1994},
abstract = {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.},
subject = {Biologie},
language = {en}
}
@article{JaschkeChungHesseetal.2012,
author = {Jaschke, Alexander and Chung, Bomee and Hesse, Deike and Kluge, Reinhart and Zahn, Claudia and Moser, Markus and Petzke, Klaus-J{\"u}rgen and Brigelius-Floh{\´e}, Regina and Puchkov, Dmytro and Koepsell, Hermann and Heeren, Joerg and Joost, Hans-Georg and Sch{\"u}rmann, Annette},
title = {The GTPase ARFRP1 controls the lipidation of chylomicrons in the Golgi of the intestinal epithelium},
series = {Human Molecular Genetics},
volume = {21},
journal = {Human Molecular Genetics},
number = {14},
doi = {10.1093/hmg/dds140},
url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-125658},
pages = {3128-3142},
year = {2012},
abstract = {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.},
language = {en}
}
@article{CardaniSardiLaFerlaetal.2014,
author = {Cardani, Diego and Sardi, Claudia and La Ferla, Barbara and D'Orazio, Guiseppe and Sommariva, Michele and Marcucci, Fabrizio and Olivero, Daniela and Tagliabue, Elda and Koepsell, Hermann and Nicotra, Francesco and Balsari, Andrea and Rumio, Christiano},
title = {Sodium glucose cotransporter 1 ligand BLF501 as a novel tool for management of gastrointestinal mucositis},
series = {Molecular Cancer},
volume = {13},
journal = {Molecular Cancer},
number = {23},
issn = {1476-4598},
doi = {10.1186/1476-4598-13-23},
url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-117352},
year = {2014},
abstract = {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.},
language = {en}
}
@article{RoederGeillingerZieteketal.2014,
author = {R{\"o}der, Pia V. and Geillinger, Kerstin E. and Zietek, Tamara S. and Thorens, Bernard and Koepsell, Hermann and Daniel, Hannelore},
title = {The Role of SGLT1 and GLUT2 in Intestinal Glucose Transport and Sensing},
series = {PLOS ONE},
volume = {9},
journal = {PLOS ONE},
number = {2},
doi = {10.1371/journal.pone.0089977},
url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-117262},
pages = {e89977},
year = {2014},
abstract = {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.},
language = {en}
}
@article{OttoFriedrichMadunićetal.2020,
author = {Otto, Christoph and Friedrich, Alexandra and Madunić, Ivana Vrhovac and Baumeier, Christian and Schwenk, Robert W. and Karaica, Dean and Germer, Christoph-Thomas and Sch{\"u}rmann, Annette and Sabolić, Ivan and Koepsell, Hermann, Hermann},
title = {Antidiabetic Effects of a Tripeptide That Decreases Abundance of Na\(^+\)-D-glucose Cotransporter SGLT1 in the Brush-Border Membrane of the Small Intestine},
series = {ACS Omega},
volume = {5},
journal = {ACS Omega},
number = {45},
doi = {10.1021/acsomega.0c03844},
url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-230654},
pages = {29127-29139},
year = {2020},
abstract = {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.},
language = {en}
}
@article{BhavsarSinghSharmaetal.2016,
author = {Bhavsar, Shefalee K. and Singh, Yogesh and Sharma, Piyush and Khairnar, Vishal and Hosseinzadeh, Zohreh and Zhang, Shaqiu and Palmada, Monica and Sabolic, Ivan and Koepsell, Hermann and Lang, Karl S. and Lang, Philipp A. and Lang, Florian},
title = {Expression of JAK3 Sensitive Na\(^+\) Coupled Glucose Carrier SGLT1 in Activated Cytotoxic T Lymphocytes},
series = {Cellular Physiology and Biochemistry},
volume = {39},
journal = {Cellular Physiology and Biochemistry},
number = {3},
doi = {10.1159/000447827},
url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-164900},
pages = {1209-1228},
year = {2016},
abstract = {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.},
language = {en}
}