DOCSLIB.ORG

Expression and Regulation of Glucose Transporters in the Bovine Mammary Gland1

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Expression and Regulation of Glucose Transporters in the Bovine Mammary Gland1 J. Dairy Sci. 90(E. Suppl.):E76–E86 doi:10.3168/jds.2006-470 © American Dairy Science Association, 2007. Expression and Regulation of Glucose Transporters in the Bovine Mammary Gland1 F.-Q. Zhao2 and A. F. Keating Lactation and Mammary Gland Biology Group, Department of Animal Science, University of Vermont, Burlington 05405 ABSTRACT Key words: glucose transporter, glucose uptake, lacta- tion, mammary gland Glucose is the primary precursor for the synthesis of lactose, which controls milk volume by maintaining the osmolarity of milk. Glucose uptake in the mammary INTRODUCTION gland plays a key role in milk production. Glucose trans- In lactating animals, providing glucose for the mam- port across the plasma membranes of mammalian cells mary gland is a metabolic priority because glucose is is carried out by 2 distinct processes: facilitative trans- the primary precursor for lactose synthesis in the mam- port, mediated by a family of facilitative glucose trans- mary epithelial cell. Because lactose maintains the os- porters (GLUT); and sodium-dependent transport, me- molarity of milk, the rate of lactose synthesis serves as + diated by the Na /glucose cotransporters (SGLT). a major factor influencing milk volume (Neville et al., Transport kinetic studies indicate that glucose trans- 1983; Cant et al., 2002). In addition to its importance port across the plasma membrane of the lactating bo- as the precursor for lactose synthesis, glucose is also vine mammary epithelial cell has a Km value of 8.29 used for the generation of ATP and the cofactor nicoti- mM for 3-O-methyl-D-glucose and can be inhibited by mamide dinucleotide phosphate and is used as a sub- both cytochalasin-B and phloretin, indicating a facilita- strate for protein, lipid, and nucleotide synthesis. The tive transport process. This is consistent with the obser- mammary gland itself cannot synthesize glucose from vation that in the lactating bovine mammary gland, other precursors because of the lack of glucose-6-phos- GLUT1 is the predominant glucose transporter. How- phatase (Scott et al., 1976; Threadgold and Kuhn, ever, the bovine lactating mammary gland also ex- 1979). Therefore, the mammary gland is dependent on presses GLUT3, GLUT4, GLUT5, GLUT8, GLUT12, the blood supply for its glucose needs. In a lactating and sodium-dependent SGLT1 and SGLT2 at different cow, 72 g of glucose is required to produce 1 kg of milk levels. Studies of protein expression and cellular and (Kronfeld, 1982). Therefore, in a cow producing 40 kg subcellular localizations of these transporters are of milk per day the mammary gland is required to take needed to address their physiological functions in the up about 3 kg of glucose daily. Indeed, mammary gland mammary gland. From late pregnancy to early lacta- uptake can account for as much as 60 to 85% of the tion, expression of GLUT1, GLUT8, GLUT12, SGLT1, total glucose that enters the blood (Annison and Linzell, and SGLT2 mRNA increases from at least 5-fold to 1964; Chaiyabutr et al., 1980; Sunehag et al., 2002, several hundred-fold, suggesting that these transport- 2003). ers may be regulated by lactogenic hormones and have Direct and indirect techniques demonstrate that a roles in milk synthesis. The GLUT1 protein is detected steep glucose concentration gradient exists across the in lactating mammary epithelial cells. Its expression basal plasma membrane of mammary epithelial cells, level decreases from early to late lactation stages and from 2.0 to 5.0 mM in plasma to 0.1 to 0.5 mM in the becomes barely detectable in the nonlactating gland. cell (Faulkner et al., 1981; Cherepanov et al., 2000). Both GLUT1 mRNA and protein levels in the lactating The intracellular glucose concentration is significantly mammary gland are not significantly affected by exoge- lower than the Km for the rate-limiting enzyme in lac- nous bovine growth hormone, and, in addition, GLUT1 tose synthesis, lactose synthase (Faulkner and Peaker, mRNA does not appear to be affected by leptin. 1987). Therefore, glucose transport across the plasma membrane may be a rate-limiting step in milk synthe- sis, and several observations support this theory. Lac- Received July 25, 2006. tose synthesis and milk yield show a linear or positive Accepted September 8, 2006. correlation with glucose uptake in the mammary gland 1Presented at the ADSA-ASAS Joint Annual Meeting, Minneapo- lis, MN, July 2006. of goats and cows (Kronfeld, 1982; Nielsen and Jakob- 2Corresponding author: [email protected] sen, 1993; Hurtaud et al., 2000; Kim et al., 2001; Niel- E76 GLUCOSE TRANSPORTERS IN BOVINE MAMMARY GLAND E77 sen et al., 2001; Cant et al., 2002; Huhtanen et al., an N-glycosylation site located on either the first or 2002). The galactopoietic effect elicited by exogenous ninth extracellular loop. The known kinetic properties, bovine growth hormone (GH) requires increased glu- major sites of expression, and proposed function of each cose uptake by mammary cells (Davis et al., 1988; of these transporters in human and rodent tissues are Mepham et al., 1990; Faulkner, 1999). Milk lactose syn- summarized in Table 1. Their tissue-specific distribu- thesis and milk yield decrease in cows treated with tion, distinct kinetic properties, and differential regula- phlorizin, a potent inhibitor of intestinal glucose ab- tion by ambient glucose and hormones, especially insu- sorption and renal glucose reabsorption by inhibiting lin, reveal that each transporter isoform plays a specific + the Na /D-glucose cotransporter (Bradford and Allen, role in glucose uptake in various tissues and in glucose 2005). Regulation of glucose transport in the bovine homeostasis (Wood and Trayhurn, 2003). mammary gland as well as in other tissues also serves The glucose transporters GLUT1 to GLUT5 have a key role in maintaining glucose homeostasis during been extensively studied. GLUT1 has been ubiquitously lactation (for reviews, see Bell, 1995; Bell and Bau- detected in cells and tissues, including the mammary man, 1997). gland (Madon et al., 1990; Burant et al., 1991; Zhao et al., 1999). In many tissues in which it is expressed, GLUCOSE TRANSPORT AND GLUCOSE GLUT1 is concentrated in the cells of blood–tissue bar- TRANSPORTERS IN MAMMALIAN CELLS riers (Cornford et al., 1994). Because of the ubiquitous distribution and cellular localization, GLUT1 is consid- The plasma membranes of virtually all mammalian ered to be the primary transporter responsible for basal cells possess one or more transport systems to allow glucose uptake. GLUT2 is involved in the release of glucose movement either into or out of the cells. In hepatic glucose, in the release of absorbed and reab- mammals, blood glucose levels are maintained within sorbed glucose in the small intestine and kidney, re- a narrow range by homeostatic mechanisms, and most spectively, and in the regulation of insulin secretion cells take up glucose by a passive, facilitative transport from β-cells. GLUT3 plays a major role as the brain process, driven by the downward glucose concentration neuronal glucose transporter. GLUT4 mediates insulin- gradient across the plasma membrane (Widdas, 1988). stimulated glucose uptake in skeletal muscle and adi- This facilitative transport is inhibitable by cytocha- pose tissues (Holman and Sandoval, 2001). GLUT5 may lasin-B or phloretin. It is believed that only in the epi- participate in the uptake of dietary fructose from the thelial cell brush border of the small intestine and the lumen of the small intestine. kidney proximal convoluted tubules is glucose absorbed GLUT6 to GLUT12 and HMIT are the most recently or reabsorbed by an active mechanism that uses the cloned facilitative glucose transporter isoforms and downward sodium concentration gradient to transport have been characterized to a lesser extent. GLUT6 glucose against its electrochemical gradient. This so- mRNA is primarily expressed in the spleen, peripheral dium-dependent transport can be inhibited by phlori- leukocytes, and brain (Doege et al., 2000a), but its activ- zin. The facilitative and sodium-dependent glucose ity is still unclear. GLUT7 was cloned from human transport systems are mediated by 2 distinct families small intestinal tissue and was also found to be ex- of glucose transporters (Table 1). pressed in the colon, testis, and prostate (Li et al., 2004); it transports both glucose and fructose with high affin- Facilitative Glucose Transporters ity (Li et al., 2004). GLUT8 is postulated to be another insulin-regulated glucose transporter because it was Saturable, stereoselective, bidirectional, and energy- found to be responsible for insulin-stimulated glucose independent facilitated diffusion is mediated by the fa- uptake in the blastocyst (Carayannopoulos et al., 2000). cilitative glucose transporters (solute carriers SLC2A, It may also be involved in providing glucose for DNA protein symbol GLUT). Thus far, 13 functional facilita- synthesis in male germ cells because it is highly ex- tive glucose transporter isoforms have been cloned, pressed in the testis, and this expression is markedly characterized and designated as GLUT1–GLUT12 inhibited by estrogen treatment (Doege et al., 2000b). (based on the chronological order of publication) and GLUT9 is found primarily in the kidney and liver (Phay H+/myo-inositol cotransporter (HMIT). A genomic-wide et al., 2000). GLUT10 has the highest levels of expres- GenBank search indicated that these 13 isoforms may sion in the liver and pancreas (McVie-Wylie et al., represent all facilitative glucose transporter members 2001), and because human GLUT10 is localized to chro- in humans (Joost and Thorens, 2001). These transport- mosome 20q12-q13.1, one of the genomic loci associated ers are structurally conserved and related, consisting with non-insulin-dependent diabetes mellitus, it may of 12 transmembrane domains with both the amino- be a candidate for a susceptibility marker for non-insu- and carboxy-terminals located in the cytoplasm, and lin-dependent diabetes mellitus. Multiple GLUT11 tis- Journal of Dairy Science Vol. 90 E. Suppl., 2007 E78 ZHAO AND KEATING Table 1.
Load more

Recommended publications
  • Iron Transport Proteins: Gateways of Cellular and Systemic Iron Homeostasis
    Iron transport proteins: Gateways of cellular and systemic iron homeostasis Mitchell D. Knutson, PhD University of Florida Essential Vocabulary Fe Heme Membrane Transport DMT1 FLVCR Ferroportin HRG1 Mitoferrin Nramp1 ZIP14 Serum Transport Transferrin Transferrin receptor 1 Cytosolic Transport PCBP1, PCBP2 Timeline of identification in mammalian iron transport Year Protein Original Publications 1947 Transferrin Laurell and Ingelman, Acta Chem Scand 1959 Transferrin receptor 1 Jandl et al., J Clin Invest 1997 DMT1 Gunshin et al., Nature; Fleming et al. Nature Genet. 1999 Nramp1 Barton et al., J Leukocyt Biol 2000 Ferroportin Donovan et al., Nature; McKie et al., Cell; Abboud et al. J. Biol Chem 2004 FLVCR Quigley et al., Cell 2006 Mitoferrin Shaw et al., Nature 2006 ZIP14 Liuzzi et al., Proc Natl Acad Sci USA 2008 PCBP1, PCBP2 Shi et al., Science 2013 HRG1 White et al., Cell Metab DMT1 (SLC11A2) • Divalent metal-ion transporter-1 • Former names: Nramp2, DCT1 Fleming et al. Nat Genet, 1997; Gunshin et al., Nature 1997 • Mediates uptake of Fe2+, Mn2+, Cd2+ • H+ coupled transporter (cotransporter, symporter) • Main roles: • intestinal iron absorption Illing et al. JBC, 2012 • iron assimilation by erythroid cells DMT1 (SLC11A2) Yanatori et al. BMC Cell Biology 2010 • 4 different isoforms: 557 – 590 a.a. (hDMT1) Hubert & Hentze, PNAS, 2002 • Function similarly in iron transport • Differ in tissue/subcellular distribution and regulation • Regulated by iron: transcriptionally (via HIF2α) post-transcriptionally (via IRE) IRE = Iron-Responsive Element Enterocyte Lumen DMT1 Fe2+ Fe2+ Portal blood Enterocyte Lumen DMT1 Fe2+ Fe2+ Fe2+ Fe2+ Ferroportin Portal blood Ferroportin (SLC40A1) • Only known mammalian iron exporter Donovan et al., Nature 2000; McKie et al., Cell 2000; Abboud et al.
    [Show full text]
  • Effect of Hydrolyzable Tannins on Glucose-Transporter Expression and Their Bioavailability in Pig Small-Intestinal 3D Cell Model
    molecules Article Effect of Hydrolyzable Tannins on Glucose-Transporter Expression and Their Bioavailability in Pig Small-Intestinal 3D Cell Model Maksimiljan Brus 1 , Robert Frangež 2, Mario Gorenjak 3 , Petra Kotnik 4,5, Željko Knez 4,5 and Dejan Škorjanc 1,* 1 Faculty of Agriculture and Life Sciences, University of Maribor, Pivola 10, 2311 Hoˇce,Slovenia; [email protected] 2 Veterinary Faculty, Institute of Preclinical Sciences, University of Ljubljana, Gerbiˇceva60, 1000 Ljubljana, Slovenia; [email protected] 3 Center for Human Molecular Genetics and Pharmacogenomics, Faculty of Medicine, University of Maribor, Taborska 8, 2000 Maribor, Slovenia; [email protected] 4 Department of Chemistry, Faculty of Medicine, University of Maribor, Taborska 8, 2000 Maribor, Slovenia; [email protected] (P.K.); [email protected] (Ž.K.) 5 Laboratory for Separation Processes and Product Design, Faculty of Chemistry and Chemical Engineering, University of Maribor, Smetanova 17, 2000 Maribor, Slovenia * Correspondence: [email protected]; Tel.: +386-2-320-90-25 Abstract: Intestinal transepithelial transport of glucose is mediated by glucose transporters, and affects postprandial blood-glucose levels. This study investigates the effect of wood extracts rich in hydrolyzable tannins (HTs) that originated from sweet chestnut (Castanea sativa Mill.) and oak (Quercus petraea) on the expression of glucose transporter genes and the uptake of glucose and HT constituents in a 3D porcine-small-intestine epithelial-cell model. The viability of epithelial cells CLAB and PSI exposed to different HTs was determined using alamarBlue®. qPCR was used to analyze the gene expression of SGLT1, GLUT2, GLUT4, and POLR2A. Glucose uptake was confirmed Citation: Brus, M.; Frangež, R.; by assay, and LC–MS/ MS was used for the analysis of HT bioavailability.
    [Show full text]
  • Renal Membrane Transport Proteins and the Transporter Genes
    Techno e lo n g Gowder, Gene Technology 2014, 3:1 e y G Gene Technology DOI; 10.4172/2329-6682.1000e109 ISSN: 2329-6682 Editorial Open Access Renal Membrane Transport Proteins and the Transporter Genes Sivakumar J T Gowder* Qassim University, College of Applied Medical Sciences, Buraidah, Kingdom of Saudi Arabia Kidney this way, high sodium diet favors urinary sodium concentration [9]. AQP2 has a role in hereditary and acquired diseases affecting urine- In humans, the kidneys are a pair of bean-shaped organs about concentrating mechanisms [10]. AQP2 regulates antidiuretic action 10 cm long and located on either side of the vertebral column. The of arginine vasopressin (AVP). The urinary excretion of this protein is kidneys constitute for less than 1% of the weight of the human body, considered to be an index of AVP signaling activity in the renal system. but they receive about 20% of blood pumped with each heartbeat. The Aquaporins are also considered as markers for chronic renal allograft renal artery transports blood to be filtered to the kidneys, and the renal dysfunction [11]. vein carries filtered blood away from the kidneys. Urine, the waste fluid formed within the kidney, exits the organ through a duct called the AQP4 ureter. The kidney is an organ of excretion, transport and metabolism. This gene encodes a member of the aquaporin family of intrinsic It is a complicated organ, comprising various cell types and having a membrane proteins. These proteins function as water-selective channels neatly designed three dimensional organization [1]. Due to structural in the plasma membrane.
    [Show full text]
  • REVIEW the Molecular Basis of Insulin
    1 REVIEW The molecular basis of insulin-stimulated glucose uptake: signalling, trafficking and potential drug targets Sophie E Leney and Jeremy M Tavare´ Department of Biochemistry, School of Medical Sciences, University of Bristol, Bristol BS8 1TD, UK (Correspondence should be addressed to J M Tavare´; Email: [email protected]) Abstract The search for the underlying mechanism through which GLUT4 translocation and will attempt to address the spatial insulin regulates glucose uptake into peripheral tissues has relationship between the signalling and trafficking com- unveiled a highly intricate network of molecules that function ponents of this event. We will also explore the degree to in concert to elicit the redistribution or ‘translocation’ of which components of the insulin signalling and GLUT4 the glucose transporter isoform GLUT4 from intracellular trafficking machinery may serve as potential targets for membranes to the cell surface. Following recent technological the development of orally available insulin mimics for the advances within this field, this review aims to bring together treatment of diabetes mellitus. the key molecular players that are thought to be involved in Journal of Endocrinology (2009) 203, 1–18 Introduction Levine & Goldstein 1958). However, the mechanism by which insulin is able to stimulate glucose uptake was not Glucose homeostasis and diabetes mellitus elucidated until the early 1980s when two independent groups demonstrated that insulin promoted the movement of The ability of insulin to stimulate glucose uptake into muscle and adipose tissue is central to the maintenance of whole- a ‘glucose transport activity’ from an intracellular membrane body glucose homeostasis. Autoimmune destruction of the pool to the plasma membrane (Cushman & Wardzala 1980, pancreatic b-cells results in a lack of insulin production Suzuki & Kono 1980).
    [Show full text]
  • Expression of Neurotransmitter Transport from Rat Brain Mrna in Xenopus Laevis Oocytes RANDY D
    Proc. Natl. Acad. Sci. USA Vol. 85, pp. 9846-9850, December 1988 Neurobiology Expression of neurotransmitter transport from rat brain mRNA in Xenopus laevis oocytes RANDY D. BLAKELY*, MICHAEL B. ROBINSONt, AND SUSAN G. AMARA* *Section of Molecular Neurobiology, Howard Hughes Medical Institute Research Laboratories, Yale University School of Medicine, 333 Cedar Street, P.O. Box 3333, New Haven, CT 06510; and tDepartments of Pediatrics and Pharmacology, Children's Seashore House, Philadelphia, PA 19104 Communicated by Charles F. Stevens, October 3, 1988 ABSTRACT To permit a molecular characterization of presently employed in our society, including cocaine, am- neurotransmitter transporter proteins, we have studied uptake phetamines, and tricyclic antidepressants (10, 11). activities induced in Xenopus laevis oocytes after injection of In sharp contrast to the detail with which other proteins adult rat forebrain, cerebellum, brainstem, and spinal cord involved in signal transduction are understood, and despite a poly(A)+ RNA. L-Glutamate uptake could be observed as early wealth of bioenergetic and kinetic studies on transport itself as 24 hr after injection, was linearly related to the quantity of (12, 13), our understanding ofthe molecular principles guiding mRNA injected, and could be induced after injection ofas little neurotransmitter uptake is considerably limited. Due, per- as 1 ng of cerebellar mRNA. Transport of radiolabeled haps, to their low abundance and poor stability in vitro (14), L-glutamate, y-aminobutyric acid, glycine, dopamine, seroto- purification strategies have as yet yielded little structural data. nin, and choline could be measured in single microinjected Only within the past few years has a Na'-dependent GABA oocytes with a regional profile consistent with the anatomical transporter from rat brain been reconstituted and purified (15).
    [Show full text]
  • Mechanistic Insights Into GLUT1 Activation and Clustering Revealed by Super-Resolution Imaging
    Mechanistic insights into GLUT1 activation and clustering revealed by super-resolution imaging Qiuyan Yana,b, Yanting Lub,c, Lulu Zhoua,b, Junling Chena, Haijiao Xua, Mingjun Caia, Yan Shia, Junguang Jianga, Wenyong Xiongc,1, Jing Gaoa,1, and Hongda Wanga,d,1 aState Key Laboratory of Electroanalytical Chemistry, Research Center of Biomembranomics, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022 Jilin, P. R. China; bSchool of Chemistry and Chemical Engineering, University of Chinese Academy of Sciences, 100049 Beijing, P. R. China; cState Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201 Yunnan, P. R. China; and dLaboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Aoshanwei, Jimo, Qingdao, 266237 Shandong, P. R. China Edited by Nieng Yan, Princeton University, Princeton, NJ, and accepted by Editorial Board Member Alan R. Fersht May 24, 2018 (received for review March 9, 2018) The glucose transporter GLUT1, a plasma membrane protein that super-resolution fluorescence microscopy, which breaks the dif- mediates glucose homeostasis in mammalian cells, is responsible fraction barrier and achieves a lateral resolution in the tens of for constitutive uptake of glucose into many tissues and organs. nanometers (17), has provided a particularly suitable tool to solve Many studies have focused on its vital physiological functions and these problems. Meanwhile, it has been proven that multiprotein close relationship with diseases. However, the molecular mecha- assemblies are dependent on cholesterol environment, and their nisms of its activation and transport are not clear, and its detailed separation and anchoring are related to the actin cytoskeleton (18, distribution pattern on cell membranes also remains unknown.
    [Show full text]
  • The Vesicular Glutamate Transporter (VGLUT): Heterologous Expression, Proteoliposome, Computational and Mass Spectral Studies
    University of Montana ScholarWorks at University of Montana Graduate Student Theses, Dissertations, & Professional Papers Graduate School 2008 The vesicular glutamate transporter (VGLUT): heterologous expression, proteoliposome, computational and mass spectral studies Chih-Kai Chao The University of Montana Follow this and additional works at: https://scholarworks.umt.edu/etd Let us know how access to this document benefits ou.y Recommended Citation Chao, Chih-Kai, "The vesicular glutamate transporter (VGLUT): heterologous expression, proteoliposome, computational and mass spectral studies" (2008). Graduate Student Theses, Dissertations, & Professional Papers. 1107. https://scholarworks.umt.edu/etd/1107 This Dissertation is brought to you for free and open access by the Graduate School at ScholarWorks at University of Montana. It has been accepted for inclusion in Graduate Student Theses, Dissertations, & Professional Papers by an authorized administrator of ScholarWorks at University of Montana. For more information, please contact [email protected]. THE VESICULAR GLUTAMATE TRANSPORTER (VGLUT): HETEROLOGOUS EXPRESSION, PROTEOLIPOSOME, COMPUTATIONAL AND MASS SPECTRAL STUDIES By Chih-Kai Chao Master of Science in Pharmaceutical Sciences, National Taiwan University, Taiwan, 1997 Bachelor of Science in Pharmacy, China Medical College, Taiwan, 1991 Dissertation presented in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Pharmacology/Pharmaceutical Sciences The University of Montana Missoula, MT Autumn 2008 Approved by: Dr. Perry J. Brown, Associate Provost Graduate Education Dr. Charles M. Thompson, Chair Department of Biomedical and Pharmaceutical Sciences Dr. Mark L. Grimes Department of Biological Sciences Dr. Diana I. Lurie Department of Biomedical and Pharmaceutical Sciences Dr. Keith K. Parker Department of Biomedical and Pharmaceutical Sciences Dr. David J.
    [Show full text]
  • Understanding the Structure-Function Relationships Between Monoamine Neurotransmitter Transporters and Their Cognate Ions and Ligands
    University of North Dakota UND Scholarly Commons Theses and Dissertations Theses, Dissertations, and Senior Projects January 2015 Understanding The trS ucture-Function Relationships Between Monoamine Neurotransmitter Transporters And Their ogC nate Ions And Ligands Bruce Felts Follow this and additional works at: https://commons.und.edu/theses Recommended Citation Felts, Bruce, "Understanding The trS ucture-Function Relationships Between Monoamine Neurotransmitter Transporters And Their Cognate Ions And Ligands" (2015). Theses and Dissertations. 1769. https://commons.und.edu/theses/1769 This Dissertation is brought to you for free and open access by the Theses, Dissertations, and Senior Projects at UND Scholarly Commons. It has been accepted for inclusion in Theses and Dissertations by an authorized administrator of UND Scholarly Commons. For more information, please contact [email protected]. UNDERSTANDING THE STRUCTURE-FUNCTION RELATIONSHIPS BETWEEN MONOAMINE NEUROTRANSMITTER TRANSPORTERS AND THEIR COGNATE IONS AND LIGANDS by Bruce F. Felts Bachelor of Science, University of Minnesota 2009 A dissertation Submitted to the Graduate Faculty of the University of North Dakota in partial fulfillment of the requirements for the degree of Doctor of Philosophy Grand Forks, North Dakota August 2015 Copyright 2015 Bruce Felts ii TABLE OF CONTENTS LIST OF FIGURES………………………………………………………………………... xii LIST OF TABLES……………………….………………………………………………… xv ACKNOWLEDGMENTS.…………………………………………………………….… xvi ABSTRACT.………………………………………………………………………….……. xviii CHAPTERS I. INTRODUCTION.………………………………………………………………… 1 The Solute Carrier Super-family of Proteins………………………………. 1 The Neurophysiologic Role of MATs……………………………………... 2 Monoamine Transporter Structure…………………………………………. 5 The Substrate Binding Pocket……………………………………… 10 The S1 binding site in LeuT………………………………... 11 The S1 binding site in MATs………………………………. 13 The S2 binding site in the extracellular vestibule………….. 14 Ion Binding Sites in MATs………………………………………… 17 The Na+ binding sites……………………………………….
    [Show full text]
  • Cooperation of Antiporter LAT2/Cd98hc with Uniporter TAT1 for Renal Reabsorption of Neutral Amino Acids
    BASIC RESEARCH www.jasn.org Cooperation of Antiporter LAT2/CD98hc with Uniporter TAT1 for Renal Reabsorption of Neutral Amino Acids Clara Vilches ,1 Emilia Boiadjieva-Knöpfel,2,3,4 Susanna Bodoy ,5,6 Simone Camargo ,2,3,4 Miguel López de Heredia ,1,7 Esther Prat ,1,7,8 Aida Ormazabal ,7,9 Rafael Artuch ,7,9 Antonio Zorzano ,5,6,10 François Verrey ,2,3,4 Virginia Nunes ,1,7,8 and Manuel Palacín 5,6,7 1Molecular Genetics Laboratory, Genes Disease and Therapy Program, Institut d’Investigació Biomèdica de Bellvitge (IDIBELL), L’Hospitalet de Llobregat, Spain; 2Department of Physiology, 3Zurich Center for Integrative Human Physiology (ZIHP), and 4Swiss National Centre of Competence in Research (NCCR), Kidney Control of Homeostasis (Kidney.CH), University of Zurich, Zurich, Switzerland; 5Department of Biochemistry and Molecular Medicine, Biology Faculty, University of Barcelona, Barcelona, Spain; 6Molecular Medicine Unit, Amino acid transporters and disease group, Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology (BIST), Barcelona, Spain; 7Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER) – U730, U731, U703, and 10Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM) – CB07/08/0017, Instituto de Salud Carlos III (ISCIII), Madrid, Spain; 8Genetics Section, Physiological Sciences Department, Health Sciences and Medicine Faculty, University of Barcelona, Barcelona, Spain; and 9Clinical Biochemistry Department, Institut de Recerca Sant Joan de Déu, Hospital Sant Joan de Déu, Esplugues de Llobregat, Spain ABSTRACT Background Reabsorption of amino acids (AAs) across the renal proximal tubule is crucial for intracellular and whole organism AA homeostasis.
    [Show full text]
  • The Na+/Glucose Cotransporter Inhibitor Canagliflozin Activates
    2784 Diabetes Volume 65, September 2016 Simon A. Hawley,1 Rebecca J. Ford,2 Brennan K. Smith,2 Graeme J. Gowans,1 Sarah J. Mancini,3 Ryan D. Pitt,2 Emily A. Day,2 Ian P. Salt,3 Gregory R. Steinberg,2 and D. Grahame Hardie1 The Na+/Glucose Cotransporter Inhibitor Canagliflozin Activates AMPK by Inhibiting Mitochondrial Function and Increasing Cellular AMP Levels Diabetes 2016;65:2784–2794 | DOI: 10.2337/db16-0058 Canagliflozin, dapagliflozin, and empagliflozin, all recently transporters that carry glucose across apical membranes approved for treatment of type 2 diabetes, were derived of polarized epithelial cells against concentration gradi- from the natural product phlorizin. They reduce hypergly- ents, driven by Na+ gradients. SGLT1 is expressed in the cemia by inhibiting glucose reuptake by sodium/glucose small intestine and responsible for most glucose uptake cotransporter (SGLT) 2 in the kidney, without affecting across the brush border membrane of enterocytes, whereas intestinal glucose uptake by SGLT1. We now report that SGLT2 is expressed in the kidney and responsible for most fl canagli ozin also activates AMPK, an effect also seen glucose readsorption in the convoluted proximal tubules. with phloretin (the aglycone breakdown product of The first identified SGLT inhibitor was a natural product, fi phlorizin), but not to any signi cant extent with dapagli- phlorizin, which is broken down in the small intestine to flozin, empagliflozin, or phlorizin. AMPK activation oc- phloretin, the aglycone form (Fig. 1). Although phlorizin curred at canagliflozin concentrations measured in had beneficial effects in hyperglycemic animals (2), it in- human plasma in clinical trials and was caused by hibits SGLT1 and SGLT2, causing adverse gastrointestinal inhibition of Complex I of the respiratory chain, leading effects (3).
    [Show full text]
  • (H-9): Sc-515731
    SAN TA C RUZ BI OTEC HNOL OG Y, INC . OCTN1/2 (H-9): sc-515731 BACKGROUND PRODUCT Carnitine ( β-hydroxy- γ-trimethylaminobutyrate) is a small, highly polar com - Each vial contains 200 µg IgG 1 kappa light chain in 1.0 ml of PBS with pound that aids in the β-oxidation of long-chain fatty acids. Organic cation/ < 0.1% sodium azide and 0.1% gelatin. carnitine transporters (OCTN) assist in the elimination of cationic com pounds, OCTN1/2 (H-9) is available conjugated to agarose (sc-515731 AC), 500 µg/ including xenobiotics, and transport carnitine for reabsorption in the kidney. 0.25 ml agarose in 1 ml, for IP; to HRP (sc-515731 HRP), 200 µg/ml, for Similar to organic cation transporters (OCT), OCTN proteins localize to the WB, IHC(P) and ELISA; to either phycoerythrin (sc-515731 PE), fluorescein plasma membrane of epithelial cells. OCTN1 is expressed in kidney, trachea, (sc-515731 FITC), Alexa Fluor ® 488 (sc-515731 AF488), Alexa Fluor ® 546 bone marrow and fetal liver. OCTN2 is abundantly expressed in kidney, skele - (sc- 515731 AF546), Alexa Fluor ® 594 (sc-515731 AF594) or Alexa Fluor ® 647 tal muscle, placenta and heart. OCTN3 is strongly expressed in testis and (sc-515731 AF647), 200 µg/ml, for WB (RGB), IF, IHC(P) and FCM; and to either weakly expressed in kidney. Mutations in the gene encoding OCTN2 leads to Alexa Fluor ® 680 (sc-515731 AF680) or Alexa Fluor ® 790 (sc-515731 AF790), systemic carnitine deficiency (SCD), an autosomal recessive disorder charac - 200 µg/ml, for Near-Infrared (NIR) WB, IF and FCM.
    [Show full text]
  • Neurotransmitter Transporters
    Annu. Rev. Neurosci. 1993. 16:73-93 NEUROTRANSMITTER TRANSPORTERS: Recent Progress 1 Susan G. Amara Vollum Institute for Advanced Biomedical Research, Oregon Health Sciences University, Portland, Oregon 97201 Michael J. Kuhar Neurosciences Branch, Addiction Research Center, National Institute on Drug Abuse, Baltimore, Maryland KEY WORDS: neurotransmitter reuptake, synaptic signal termination, uptake INTRODUCTION It has been known for many years that neurons and glia can accumulate neurotransmitters by a sodium dependent cotransport process that is, in many respects, similar to systems present in most cells for concentrating metabolites. By cotransporting a solute with sodium, the energy stored in transmembrane electrochemical gradients can be used to drive the solute by MCGILL UNIVERSITY LIBRARIES on 02/24/13. For personal use only. Annu. Rev. Neurosci. 1993.16:73-93. Downloaded from www.annualreviews.org into the cell (reviewed in Kanner & Schuldiner 1987; Trendelenburg 1991). A special appreciation of the neurotransmitter cotransport systems has devcIoped from studies, which indicate the existence of multiple uptake systems, each relatively selective for a specific neurotransmitter. Table I presents a list of brain uptake systems that have been identified. These transport activities are localized within the synaptic membranes of neurons that use the same transmitter and are probably the most important mech­ anism for terminating synaptic transmission. Many of these transporters I The US government has the right to retain a nonexclusive, royalty-free license in and to any copyright covering this paper. 73 74 AMARA & KUHAR Table 1 Neurotransmitter (candidates) have high affinitytransport systems Dopamine GABA Norepinephrine Glycine Serotonin Taurine Glutamate Proline Aspartate Adenosine or reuptake systems have been implicated as important sites for drug action.
    [Show full text]