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Otto C, Friedrich A, Vrhovac Madunić I, Baumeier C, Schwenk RW, Karaica D, Germer CT, Schürmann A, Sabolić I, Koepsell H. Antidiabetic Effects of a Tripeptide That Decreases Abundance of Na +-d-glucose Cotransporter SGLT1 in the Brush-Border Membrane of the Small Intestine. ACS OMEGA 2020; 5:29127-29139. [PMID: 33225144 PMCID: PMC7675577 DOI: 10.1021/acsomega.0c03844] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Accepted: 10/16/2020] [Indexed: 05/08/2023]
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.
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Affiliation(s)
- Christoph Otto
- Department
of General, Visceral, Transplantation, Vascular and Pediatric Surgery, University Hospital of Würzburg, 97080 Würzburg, Germany
| | - Alexandra Friedrich
- Institute
of Anatomy and Cell Biology, University
of Würzburg, 97070 Würzburg, Germany
| | - Ivana Vrhovac Madunić
- Molecular
Toxicology Unit, Institute for Medical Research
and Occupational Health, 10000 Zagreb, Croatia
| | - Christian Baumeier
- Department
of Experimental Diabetology, German Institute
of Human Nutrition, 14558 Potsdam-Rehbruecke, Germany
- German
Center for Diabetes Research (DZD), 85764 München-Neuherberg, Germany
| | - Robert W. Schwenk
- Department
of Experimental Diabetology, German Institute
of Human Nutrition, 14558 Potsdam-Rehbruecke, Germany
- German
Center for Diabetes Research (DZD), 85764 München-Neuherberg, Germany
| | - Dean Karaica
- Molecular
Toxicology Unit, Institute for Medical Research
and Occupational Health, 10000 Zagreb, Croatia
| | - Christoph-Thomas Germer
- Department
of General, Visceral, Transplantation, Vascular and Pediatric Surgery, University Hospital of Würzburg, 97080 Würzburg, Germany
| | - Annette Schürmann
- Department
of Experimental Diabetology, German Institute
of Human Nutrition, 14558 Potsdam-Rehbruecke, Germany
- German
Center for Diabetes Research (DZD), 85764 München-Neuherberg, Germany
| | - Ivan Sabolić
- Molecular
Toxicology Unit, Institute for Medical Research
and Occupational Health, 10000 Zagreb, Croatia
| | - Hermann Koepsell
- Institute
of Anatomy and Cell Biology, University
of Würzburg, 97070 Würzburg, Germany
- . Phone: +49-0151 23532479
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Pastor-Anglada M, Urtasun N, Pérez-Torras S. Intestinal Nucleoside Transporters: Function, Expression, and Regulation. Compr Physiol 2018; 8:1003-1017. [PMID: 29978890 DOI: 10.1002/cphy.c170039] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The gastrointestinal tract is the absorptive organ for nutrients found in foods after digestion. Nucleosides and, to a lesser extent nucleobases, are the late products of nucleoprotein digestion. These metabolites are absorbed by nucleoside (and nucleobase) transporter (NT) proteins. NTs are differentially distributed along the gastrointestinal tract showing also polarized expression in epithelial cells. Concentrative nucleoside transporters (CNTs) are mainly located at the apical side of enterocytes, whereas equilibrative nucleoside transporters (ENTs) facilitate the basolateral efflux of nucleosides and nucleobases to the bloodstream. Moreover, selected nucleotides and the bioactive nucleoside adenosine act directly on intestinal cells modulating purinergic signaling. NT-polarized insertion is tightly regulated. However, not much is known about the modulation of intestinal NT function in humans, probably due to the lack of appropriate cell models retaining CNT functional expression. Thus, the possibility of nutritional regulation of intestinal NTs has been addressed using animal models. Besides the nutrition-related role of NT proteins, orally administered drugs also need to cross the intestinal barrier, this event being a major determinant of drug bioavailability. In this regard, NT proteins might also play a role in pharmacology, thereby allowing the absorption of nucleoside- and nucleobase-derived drugs. The relative broad selectivity of these membrane transporters also suggests clinically relevant drug-drug interactions when using combined therapies. This review focuses on all these physiological and pharmacological aspects of NT protein biology. © 2017 American Physiological Society. Compr Physiol 8:1003-1017, 2018.
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Affiliation(s)
- Marçal Pastor-Anglada
- Biochemistry and Molecular Pharmacology Section, Department of Biochemistry and Molecular Biomedicine, Institute of Biomedicine (IBUB), University of Barcelona, Barcelona, Spain.,Oncology Program, National Biomedical Research Institute on Liver and Gastrointestinal Diseases (CIBER EHD), Instituto de Salud Carlos III, Barcelona, Spain.,Genetics, Molecular Biology and Gene Therapy Program, Institut de Recerca Sant Joan de Déu (IR SJD), Esplugues de Llobregat, Barcelona, Spain
| | - Nerea Urtasun
- Biochemistry and Molecular Pharmacology Section, Department of Biochemistry and Molecular Biomedicine, Institute of Biomedicine (IBUB), University of Barcelona, Barcelona, Spain.,Oncology Program, National Biomedical Research Institute on Liver and Gastrointestinal Diseases (CIBER EHD), Instituto de Salud Carlos III, Barcelona, Spain.,Genetics, Molecular Biology and Gene Therapy Program, Institut de Recerca Sant Joan de Déu (IR SJD), Esplugues de Llobregat, Barcelona, Spain
| | - Sandra Pérez-Torras
- Biochemistry and Molecular Pharmacology Section, Department of Biochemistry and Molecular Biomedicine, Institute of Biomedicine (IBUB), University of Barcelona, Barcelona, Spain.,Oncology Program, National Biomedical Research Institute on Liver and Gastrointestinal Diseases (CIBER EHD), Instituto de Salud Carlos III, Barcelona, Spain.,Genetics, Molecular Biology and Gene Therapy Program, Institut de Recerca Sant Joan de Déu (IR SJD), Esplugues de Llobregat, Barcelona, Spain
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3
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Pastor-Anglada M, Pérez-Torras S. Emerging Roles of Nucleoside Transporters. Front Pharmacol 2018; 9:606. [PMID: 29928232 PMCID: PMC5997781 DOI: 10.3389/fphar.2018.00606] [Citation(s) in RCA: 95] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Accepted: 05/21/2018] [Indexed: 01/02/2023] Open
Abstract
Since human Nucleoside Transporters (hNTs) were identified by their activity as transport systems, extensive work has been done to fully characterize them at the molecular and physiological level. Many efforts have been addressed to the identification of their selectivity for natural substrates and nucleoside analogs used to treat several diseases. hNTs belong to two different gene families, SLC28 and SLC29, encoding human Concentrative Nucleoside Transporters (hCNTs) and human Equilibrative Nucleoside Transporters (hENTs), respectively. hCNTs and hENTs are integral membrane proteins, albeit structurally unrelated. Both families share common features as substrate selectivity and often tissue localization. This apparent biological redundancy may anticipate some different roles for hCNTs and hENTs in cell physiology. Thus, hENTs may have a major role in maintaining nucleoside homeostasis, whereas hCNTs could contribute to nucleoside sensing and signal transduction. In this sense, the ascription of hCNT1 to a transceptor reinforces this hypothesis. Moreover, some evidences could suggest a putative role of hCNT2 and hCNT3 as transceptors. The interacting proteins identified for hCNT2 suggest a link to energy metabolism. Moreover, the ability of hCNT2 and hCNT3 to transport adenosine links both proteins to purinergic signaling. On the other hand, the broad selectivity transporters hENTs have a crucial role in salvage pathways and purinergic signaling by means of nucleoside pools regulation. In particular, the two new hENT2 isoforms recently described together with hENT2 seem to be key elements controlling nucleoside and nucleotide pools for DNA synthesis. This review focuses on all these NTs functions beyond their mere translocation ability.
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Affiliation(s)
- Marçal Pastor-Anglada
- Biochemistry and Molecular Pharmacology Section, Department of Biochemistry and Molecular Biomedicine, Institute of Biomedicine (IBUB), University of Barcelona, Barcelona, Spain
| | - Sandra Pérez-Torras
- Biochemistry and Molecular Pharmacology Section, Department of Biochemistry and Molecular Biomedicine, Institute of Biomedicine (IBUB), University of Barcelona, Barcelona, Spain
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Jiraskova L, Cerveny L, Karbanova S, Ptackova Z, Staud F. Expression of Concentrative Nucleoside Transporters ( SLC28A) in the Human Placenta: Effects of Gestation Age and Prototype Differentiation-Affecting Agents. Mol Pharm 2018; 15:2732-2741. [PMID: 29782174 DOI: 10.1021/acs.molpharmaceut.8b00238] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Equilibrative ( SLC29A) and concentrative ( SLC28A) nucleoside transporters contribute to proper placental development and mediate uptake of nucleosides/nucleoside-derived drugs. We analyzed placental expression of SLC28A mRNA during gestation. Moreover, we studied in choriocarcinoma-derived BeWo cells whether SLC29A and SLC28A mRNA levels can be modulated by activity of adenylyl cyclase, retinoic acid receptor activation, CpG islands methylation, or histone acetylation, using forskolin, all- trans-retinoic acid, 5-azacytidine, and sodium butyrate/sodium valproate, respectively. We found that expression of SLC28A1, SLC28A2, and SLC28A3 increases during gestation and reveals considerable interindividual variability. SLC28A2 was shown to be a dominant subtype in the first-trimester and term human placenta, while SLC28A1 exhibited negligible expression in the term placenta only. In BeWo cells, we detected mRNA of SLC28A2 and SLC28A3. Levels of the latter were affected by 5-azacytidine and all- trans-retinoic acid, while the former was modulated by sodium valproate (but not sodium butyrate), all- trans-retinoic acid, 5-azacytidine, and forskolin that caused 25-fold increase in SLC28A2 mRNA; we documented by analysis of syncytin-1 that the observed changes in SLC28A expression do not correlate with the morphological differentiation state of BeWo cells. Upregulated SLC28A2 mRNA was reflected in elevated uptake of [3H]-adenosine, high-affinity substrate of concentrative nucleoside transporter 2. Using KT-5720 and inhibitors of phosphodiesterases, we subsequently confirmed importance of cAMP/protein kinase A pathway in SLC28A2 regulation. On the other hand, SLC29A genes exhibited constitutive expression and none of the tested compounds increased SLC28A1 expression to detectable levels. In conclusion, we provide the first evidence that methylation status and activation of retinoic acid receptor affect placental SLC28A2 and SLC28A3 transcription and substrates of concentrative nucleoside transporter 2 might be taken up in higher extent in placentas with overactivated cAMP/protein kinase A pathway and likely in the term placenta.
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Affiliation(s)
- Lucie Jiraskova
- Department of Pharmacology and Toxicology , Charles University, Faculty of Pharmacy in Hradec Kralove , Akademika Heyrovskeho 1203 , 50005 Hradec Kralove , Czech Republic
| | - Lukas Cerveny
- Department of Pharmacology and Toxicology , Charles University, Faculty of Pharmacy in Hradec Kralove , Akademika Heyrovskeho 1203 , 50005 Hradec Kralove , Czech Republic
| | - Sara Karbanova
- Department of Pharmacology and Toxicology , Charles University, Faculty of Pharmacy in Hradec Kralove , Akademika Heyrovskeho 1203 , 50005 Hradec Kralove , Czech Republic
| | - Zuzana Ptackova
- Department of Pharmacology and Toxicology , Charles University, Faculty of Pharmacy in Hradec Kralove , Akademika Heyrovskeho 1203 , 50005 Hradec Kralove , Czech Republic
| | - Frantisek Staud
- Department of Pharmacology and Toxicology , Charles University, Faculty of Pharmacy in Hradec Kralove , Akademika Heyrovskeho 1203 , 50005 Hradec Kralove , Czech Republic
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Chintalapati C, Keller T, Mueller TD, Gorboulev V, Schäfer N, Zilkowski I, Veyhl-Wichmann M, Geiger D, Groll J, Koepsell H. Protein RS1 (RSC1A1) Downregulates the Exocytotic Pathway of Glucose Transporter SGLT1 at Low Intracellular Glucose via Inhibition of Ornithine Decarboxylase. Mol Pharmacol 2016; 90:508-521. [DOI: 10.1124/mol.116.104521] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Accepted: 08/16/2016] [Indexed: 01/31/2023] Open
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6
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Fernández‐Calotti P, Casulleras O, Antolin M, Guarner F, Pastor‐Anglada M. Galectin‐4 interacts with the drug transporter human concentrative nucleoside transporter 3 to regulate its function. FASEB J 2015; 30:544-54. [DOI: 10.1096/fj.15-272773] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Accepted: 09/21/2015] [Indexed: 12/31/2022]
Affiliation(s)
- Paula Fernández‐Calotti
- Department of Biochemistry and Molecular BiologyUniversity of BarcelonaInstitute of Biomedicine (IBUB)BarcelonaSpain
- Oncology ProgramNational Biomedical Research Institute of Liver and Gastrointestinal Diseases (CIBER EHD)Instituto de Salud Carlos IIIMadridSpain
| | - Olga Casulleras
- Department of Biochemistry and Molecular BiologyUniversity of BarcelonaInstitute of Biomedicine (IBUB)BarcelonaSpain
- Oncology ProgramNational Biomedical Research Institute of Liver and Gastrointestinal Diseases (CIBER EHD)Instituto de Salud Carlos IIIMadridSpain
| | - María Antolin
- Department of GastroenterologyDigestive System Research UnitInstitut de Recerca Vall d'HebronUniversity Hospital Vall d'HebronUniversitat Autònoma de Barcelona, CIBER EHDBarcelonaSpain
| | - Francisco Guarner
- Department of GastroenterologyDigestive System Research UnitInstitut de Recerca Vall d'HebronUniversity Hospital Vall d'HebronUniversitat Autònoma de Barcelona, CIBER EHDBarcelonaSpain
| | - Marçal Pastor‐Anglada
- Department of Biochemistry and Molecular BiologyUniversity of BarcelonaInstitute of Biomedicine (IBUB)BarcelonaSpain
- Oncology ProgramNational Biomedical Research Institute of Liver and Gastrointestinal Diseases (CIBER EHD)Instituto de Salud Carlos IIIMadridSpain
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7
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Veyhl-Wichmann M, Friedrich A, Vernaleken A, Singh S, Kipp H, Gorboulev V, Keller T, Chintalapati C, Pipkorn R, Pastor-Anglada M, Groll J, Koepsell H. Phosphorylation of RS1 (RSC1A1) Steers Inhibition of Different Exocytotic Pathways for Glucose Transporter SGLT1 and Nucleoside Transporter CNT1, and an RS1-Derived Peptide Inhibits Glucose Absorption. Mol Pharmacol 2015; 89:118-32. [DOI: 10.1124/mol.115.101162] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Accepted: 10/09/2015] [Indexed: 11/22/2022] Open
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8
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Wong PP, Demircioglu F, Ghazaly E, Alrawashdeh W, Stratford MRL, Scudamore CL, Cereser B, Crnogorac-Jurcevic T, McDonald S, Elia G, Hagemann T, Kocher HM, Hodivala-Dilke KM. Dual-action combination therapy enhances angiogenesis while reducing tumor growth and spread. Cancer Cell 2015; 27:123-37. [PMID: 25584895 DOI: 10.1016/j.ccell.2014.10.015] [Citation(s) in RCA: 153] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/24/2014] [Revised: 08/12/2014] [Accepted: 10/27/2014] [Indexed: 01/04/2023]
Abstract
Increasing chemotherapy delivery to tumors, while enhancing drug uptake and reducing side effects, is a primary goal of cancer research. In mouse and human cancer models in vivo, we show that coadministration of low-dose Cilengitide and Verapamil increases tumor angiogenesis, leakiness, blood flow, and Gemcitabine delivery. This approach reduces tumor growth, metastasis, and minimizes side effects while extending survival. At a molecular level, this strategy alters Gemcitabine transporter and metabolizing enzyme expression levels, enhancing the potency of Gemcitabine within tumor cells in vivo and in vitro. Thus, the dual action of low-dose Cilengitide, in vessels and tumor cells, improves chemotherapy efficacy. Overall, our data demonstrate that vascular promotion therapy is a means to improve cancer treatment.
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Affiliation(s)
- Ping-Pui Wong
- Centre for Tumor Biology, Barts Cancer Institute-a CR-UK Centre of Excellence, Queen Mary University of London, John Vane Science Centre, Charterhouse Square, London EC1M 6BQ, UK
| | - Fevzi Demircioglu
- Centre for Tumor Biology, Barts Cancer Institute-a CR-UK Centre of Excellence, Queen Mary University of London, John Vane Science Centre, Charterhouse Square, London EC1M 6BQ, UK
| | - Essam Ghazaly
- Centre for Haemato-Oncology, Barts Cancer Institute-a CR-UK Centre of Excellence, Queen Mary University of London, John Vane Science Centre, Charterhouse Square, London EC1M 6BQ, UK
| | - Wasfi Alrawashdeh
- Centre for Molecular Oncology, Barts Cancer Institute-a CR-UK Centre of Excellence, Queen Mary University of London, John Vane Science Centre, Charterhouse Square, London EC1M 6BQ, UK
| | - Michael R L Stratford
- CRUK/MRC Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, Old Road Campus Research Building, Oxford OX3 7DQ, UK
| | - Cheryl L Scudamore
- Mary Lyon Centre, MRC Harwell, Harwell Science and Innovation Campus, Oxfordshire OX11 0RD, UK
| | - Biancastella Cereser
- Centre for Tumor Biology, Barts Cancer Institute-a CR-UK Centre of Excellence, Queen Mary University of London, John Vane Science Centre, Charterhouse Square, London EC1M 6BQ, UK
| | - Tatjana Crnogorac-Jurcevic
- Centre for Molecular Oncology, Barts Cancer Institute-a CR-UK Centre of Excellence, Queen Mary University of London, John Vane Science Centre, Charterhouse Square, London EC1M 6BQ, UK
| | - Stuart McDonald
- Centre for Tumor Biology, Barts Cancer Institute-a CR-UK Centre of Excellence, Queen Mary University of London, John Vane Science Centre, Charterhouse Square, London EC1M 6BQ, UK
| | - George Elia
- Centre for Tumor Biology, Barts Cancer Institute-a CR-UK Centre of Excellence, Queen Mary University of London, John Vane Science Centre, Charterhouse Square, London EC1M 6BQ, UK
| | - Thorsten Hagemann
- Centre for Cancer Inflammation, Barts Cancer Institute-a CR-UK Centre of Excellence, Queen Mary University of London, John Vane Science Centre, Charterhouse Square, London EC1M 6BQ, UK; Barts and the London HPB Centre, The Royal London Hospital, Barts Health NHS Trust, London E1 1BB, UK
| | - Hemant M Kocher
- Centre for Tumor Biology, Barts Cancer Institute-a CR-UK Centre of Excellence, Queen Mary University of London, John Vane Science Centre, Charterhouse Square, London EC1M 6BQ, UK; Barts and the London HPB Centre, The Royal London Hospital, Barts Health NHS Trust, London E1 1BB, UK
| | - Kairbaan M Hodivala-Dilke
- Centre for Tumor Biology, Barts Cancer Institute-a CR-UK Centre of Excellence, Queen Mary University of London, John Vane Science Centre, Charterhouse Square, London EC1M 6BQ, UK.
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Li Q, Yang H, Peng X, Guo D, Dong Z, Polli JE, Shu Y. Ischemia/Reperfusion-inducible protein modulates the function of organic cation transporter 1 and multidrug and toxin extrusion 1. Mol Pharm 2013; 10:2578-87. [PMID: 23651427 DOI: 10.1021/mp400013t] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The recently identified ischemia/reperfusion-inducible protein (IRIP) has been reported to negatively modulate the activities of several transporters in cell culture systems. The goal of this study is to determine whether IRIP regulates the activities of OCT1 and MATE1, and hence the disposition in vivo of their substrate metformin, a therapeutic drug for diabetes and other obesity-related syndromes. In the uptake studies in the human embryonic kidney 293 cells overexpressing IRIP with and without OCT1 or MATE1, IRIP overexpression was found to significantly inhibit the uptake of 1-methyl-4-phenylpyridinium mediated by OCT1 or MATE1. In contrast, knockdown of IRIP by small hairpin RNA (shRNA) increased the transporter activities in vitro. IRIP overexpression decreased the membrane localization of transporter proteins without any changes in transcript levels in cells. By overexpressing IRIP in mouse liver via hydrodynamic tail vein injection, we demonstrated that increased IRIP expression could cause a significant reduction in hepatic accumulation of metformin (P < 0.01). In addition, we observed that the expression of IRIP was approximately half (P < 0.01) in ob/ob mice when compared to their lean littermates, with significant increases in hepatic Oct1 protein expression and metformin accumulation. In conclusion, IRIP negatively modulates the function of OCT1 and MATE1 in cells. Importantly, we provide in vivo evidence for such modulation that may cause an alteration in drug disposition. The regulation by IRIP on transporter activities likely occurs at a post-transcriptional level, and future studies are needed to characterize the exact mechanism.
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Affiliation(s)
- Qing Li
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland at Baltimore, Baltimore, Maryland, United States
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Klein DM, Evans KK, Hardwick RN, Dantzler WH, Wright SH, Cherrington NJ. Basolateral uptake of nucleosides by Sertoli cells is mediated primarily by equilibrative nucleoside transporter 1. J Pharmacol Exp Ther 2013; 346:121-9. [PMID: 23639800 DOI: 10.1124/jpet.113.203265] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The blood-testis barrier (BTB) prevents the entry of many xenobiotic compounds into seminiferous tubules thereby protecting developing germ cells. Understanding drug transport across the BTB may improve drug delivery into the testis. Members of one class of drug, nucleoside reverse transcriptase inhibitors (NRTIs), do penetrate the BTB, presumably through interaction with physiologic nucleoside transporters. By investigating the mechanism of nucleoside transport, it may be possible to design other drugs to bypass the BTB in a similar manner. We present a novel ex vivo technique to study transport at the BTB that employs isolated, intact seminiferous tubules. Using this system, we found that over 80% of total uptake by seminiferous tubules of the model nucleoside uridine could be inhibited by 100 nM nitrobenzylmercaptopurine riboside (NBMPR, 6-S-[(4-nitrophenyl)methyl]-6-thioinosine), a concentration that selectively inhibits equilibrative nucleoside transporter 1 (ENT1) activity. In primary cultured rat Sertoli cells, 100 nM NBMPR inhibited all transepithelial transport and basolateral uptake of uridine. Immunohistochemical staining showed ENT1 to be located on the basolateral membrane of human and rat Sertoli cells, whereas ENT2 was located on the apical membrane of Sertoli cells. Transepithelial transport of uridine by rat Sertoli cells was partially inhibited by the NRTIs zidovudine, didanosine, and tenofovir disoproxil fumarate, consistent with an interaction between these drugs and ENT transporters. These data indicate that ENT1 is the primary route for basolateral nucleoside uptake into Sertoli cells and a possible mechanism for nucleosides and nucleoside-based drugs to undergo transepithelial transport.
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Affiliation(s)
- David M Klein
- Department of Pharmacology and Toxicology, University of Arizona, Tucson, Arizona, USA
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