1
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Laddha AP, Dzielak L, Lewis C, Xue R, Manautou JE. Impact of non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH) on the expression and function of hepatobiliary transporters: A comprehensive mechanistic review. Biochim Biophys Acta Mol Basis Dis 2024; 1870:167037. [PMID: 38295624 DOI: 10.1016/j.bbadis.2024.167037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Revised: 01/11/2024] [Accepted: 01/20/2024] [Indexed: 02/02/2024]
Abstract
The liver plays a central role in the biotransformation and disposition of endogenous molecules and xenobiotics. In addition to drug-metabolizing enzymes, transporter proteins are key determinants of drug hepatic clearance. Hepatic transporters are transmembrane proteins that facilitate the movement of chemicals between sinusoidal blood and hepatocytes. Other drug transporters translocate molecules from hepatocytes into bile canaliculi for biliary excretion. The formers are known as basolateral, while the latter are known as canalicular transporters. Also, these transporters are classified into two super-families, the solute carrier transporter (SLC) and the adenosine triphosphate (ATP)-binding cassette (ABC) transporter. The expression and function of transporters involve complex regulatory mechanisms, which are contributing factors to interindividual variability in drug pharmacokinetics and disposition. A considerable number of liver diseases are known to alter the expression and function of drug transporters. Among them, non-alcoholic fatty liver disease (NAFLD) is a chronic condition with a rapidly increasing incidence worldwide. NAFLD, recently reclassified as metabolic dysfunction-associated steatotic liver disease (MASLD), is a disease continuum that includes steatosis with or without mild inflammation (NASH), and potentially neuroinflammatory pathology. NASH is additionally characterized by the presence of hepatocellular injury. During NAFLD and NASH, drug transporters exhibit altered expression and function, leading to altered drug pharmacokinetics and pharmacodynamics, thus increasing the risk of adverse drug reactions. The purpose of the present review is to provide comprehensive mechanistic information on the expression and function of hepatic transporters under fatty liver conditions and hence, the impact on the pharmacokinetic profiles of certain drugs from the available pre-clinical and clinical literature.
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Affiliation(s)
- Ankit P Laddha
- Department of Pharmaceutical Sciences, University of Connecticut, Storrs, CT, USA
| | - Lindsey Dzielak
- Department of Pharmaceutical Sciences, University of Connecticut, Storrs, CT, USA; Non-Clinical Drug Safety (NDS) Department, Boehringer Ingelheim Pharmaceutical Co., Ridgefield, CT, USA
| | - Cedric Lewis
- Non-Clinical Drug Safety (NDS) Department, Boehringer Ingelheim Pharmaceutical Co., Ridgefield, CT, USA
| | - Raymond Xue
- Charles River Laboratories, Inc., Shrewsbury, MA, USA
| | - José E Manautou
- Department of Pharmaceutical Sciences, University of Connecticut, Storrs, CT, USA.
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2
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Partial proteolysis improves the identification of the extracellular segments of transmembrane proteins by surface biotinylation. Sci Rep 2020; 10:8880. [PMID: 32483232 PMCID: PMC7264363 DOI: 10.1038/s41598-020-65831-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Accepted: 05/08/2020] [Indexed: 01/11/2023] Open
Abstract
Transmembrane proteins (TMP) play a crucial role in several physiological processes. Despite their importance and diversity, only a few TMP structures have been determined by high-resolution protein structure characterization methods so far. Due to the low number of determined TMP structures, the parallel development of various bioinformatics and experimental methods was necessary for their topological characterization. The combination of these methods is a powerful approach in the determination of TMP topology as in the Constrained Consensus TOPology prediction. To support the prediction, we previously developed a high-throughput topology characterization method based on primary amino group-labelling that is still limited in identifying all TMPs and their extracellular segments on the surface of a particular cell type. In order to generate more topology information, a new step, a partial proteolysis of the cell surface has been introduced to our method. This step results in new primary amino groups in the proteins that can be biotinylated with a membrane-impermeable agent while the cells still remain intact. Pre-digestion also promotes the emergence of modified peptides that are more suitable for MS/MS analysis. The modified sites can be utilized as extracellular constraints in topology predictions and may contribute to the refined topology of these proteins.
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3
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Müller A, Langó T, Turiák L, Ács A, Várady G, Kucsma N, Drahos L, Tusnády GE. Covalently modified carboxyl side chains on cell surface leads to a novel method toward topology analysis of transmembrane proteins. Sci Rep 2019; 9:15729. [PMID: 31673029 PMCID: PMC6823493 DOI: 10.1038/s41598-019-52188-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Accepted: 10/05/2019] [Indexed: 12/13/2022] Open
Abstract
The research on transmembrane proteins (TMPs) is quite widespread due to their biological importance. Unfortunately, only a little amount of structural data is available of TMPs. Since technical difficulties arise during their high-resolution structure determination, bioinformatics and other experimental approaches are widely used to characterize their low-resolution structure, namely topology. Experimental and computational methods alone are still limited to determine TMP topology, but their combination becomes significant for the production of reliable structural data. By applying amino acid specific membrane-impermeable labelling agents, it is possible to identify the accessible surface of TMPs. Depending on the residue-specific modifications, new extracellular topology data is gathered, allowing the identification of more extracellular segments for TMPs. A new method has been developed for the experimental analysis of TMPs: covalent modification of the carboxyl groups on the accessible cell surface, followed by the isolation and digestion of these proteins. The labelled peptide fragments and their exact modification sites are identified by nanoLC-MS/MS. The determined peptides are mapped to the primary sequences of TMPs and the labelled sites are utilised as extracellular constraints in topology predictions that contribute to the refined low-resolution structure data of these proteins.
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Affiliation(s)
- Anna Müller
- Institute of Enzymology, RCNS, Hungarian Academy of Sciences, Magyar Tudósok krt 2, Budapest, H-1117, Hungary
| | - Tamás Langó
- Institute of Enzymology, RCNS, Hungarian Academy of Sciences, Magyar Tudósok krt 2, Budapest, H-1117, Hungary
| | - Lilla Turiák
- Institute of Organic Chemistry, RCNS, Hungarian Academy of Sciences, Magyar Tudósok krt 2, Budapest, H-1117, Hungary
| | - András Ács
- Institute of Organic Chemistry, RCNS, Hungarian Academy of Sciences, Magyar Tudósok krt 2, Budapest, H-1117, Hungary
| | - György Várady
- Institute of Enzymology, RCNS, Hungarian Academy of Sciences, Magyar Tudósok krt 2, Budapest, H-1117, Hungary
| | - Nóra Kucsma
- Institute of Enzymology, RCNS, Hungarian Academy of Sciences, Magyar Tudósok krt 2, Budapest, H-1117, Hungary
| | - László Drahos
- Institute of Organic Chemistry, RCNS, Hungarian Academy of Sciences, Magyar Tudósok krt 2, Budapest, H-1117, Hungary
| | - Gábor E Tusnády
- Institute of Enzymology, RCNS, Hungarian Academy of Sciences, Magyar Tudósok krt 2, Budapest, H-1117, Hungary.
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4
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Zou L, Stecula A, Gupta A, Prasad B, Chien HC, Yee SW, Wang L, Unadkat JD, Stahl SH, Fenner KS, Giacomini KM. Molecular Mechanisms for Species Differences in Organic Anion Transporter 1, OAT1: Implications for Renal Drug Toxicity. Mol Pharmacol 2018; 94:689-699. [PMID: 29720497 DOI: 10.1124/mol.117.111153] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Accepted: 04/25/2018] [Indexed: 12/31/2022] Open
Abstract
Species differences in renal drug transporters continue to plague drug development with animal models failing to adequately predict renal drug toxicity. For example, adefovir, a renally excreted antiviral drug, failed clinical studies for human immunodeficiency virus due to pronounced nephrotoxicity in humans. In this study, we demonstrated that there are large species differences in the kinetics of interactions of a key class of antiviral drugs, acyclic nucleoside phosphonates (ANPs), with organic anion transporter 1 [(OAT1) SLC22A6] and identified a key amino acid residue responsible for these differences. In OAT1 stably transfected human embryonic kidney 293 cells, the Km value of tenofovir for human OAT1 (hOAT1) was significantly lower than for OAT1 orthologs from common preclinical animals, including cynomolgus monkey, mouse, rat, and dog. Chimeric and site-directed mutagenesis studies along with comparative structure modeling identified serine at position 203 (S203) in hOAT1 as a determinant of its lower Km value. Furthermore, S203 is conserved in apes, and in contrast alanine at the equivalent position is conserved in preclinical animals and Old World monkeys, the most related primates to apes. Intriguingly, transport efficiencies are significantly higher for OAT1 orthologs from apes with high serum uric acid (SUA) levels than for the orthologs from species with low serum uric acid levels. In conclusion, our data provide a molecular mechanism underlying species differences in renal accumulation of nephrotoxic ANPs and a novel insight into OAT1 transport function in primate evolution.
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Affiliation(s)
- Ling Zou
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, California (L.Z., A.S., H.-C.C., S.W.Y., K.M.G.); Pharmacokinetics and Drug Metabolism, Amgen Inc., Cambridge, Massachusetts (A.G.); Department of Pharmaceutics, School of Pharmacy, University of Washington, Seattle, Washington (B.P., L.W., J.D.U.); and Safety and ADME Translational Sciences, Drug Safety and Metabolism, IMED Biotech Unit, AstraZeneca, Cambridge, UK (S.H.S., K.S.F.)
| | - Adrian Stecula
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, California (L.Z., A.S., H.-C.C., S.W.Y., K.M.G.); Pharmacokinetics and Drug Metabolism, Amgen Inc., Cambridge, Massachusetts (A.G.); Department of Pharmaceutics, School of Pharmacy, University of Washington, Seattle, Washington (B.P., L.W., J.D.U.); and Safety and ADME Translational Sciences, Drug Safety and Metabolism, IMED Biotech Unit, AstraZeneca, Cambridge, UK (S.H.S., K.S.F.)
| | - Anshul Gupta
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, California (L.Z., A.S., H.-C.C., S.W.Y., K.M.G.); Pharmacokinetics and Drug Metabolism, Amgen Inc., Cambridge, Massachusetts (A.G.); Department of Pharmaceutics, School of Pharmacy, University of Washington, Seattle, Washington (B.P., L.W., J.D.U.); and Safety and ADME Translational Sciences, Drug Safety and Metabolism, IMED Biotech Unit, AstraZeneca, Cambridge, UK (S.H.S., K.S.F.)
| | - Bhagwat Prasad
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, California (L.Z., A.S., H.-C.C., S.W.Y., K.M.G.); Pharmacokinetics and Drug Metabolism, Amgen Inc., Cambridge, Massachusetts (A.G.); Department of Pharmaceutics, School of Pharmacy, University of Washington, Seattle, Washington (B.P., L.W., J.D.U.); and Safety and ADME Translational Sciences, Drug Safety and Metabolism, IMED Biotech Unit, AstraZeneca, Cambridge, UK (S.H.S., K.S.F.)
| | - Huan-Chieh Chien
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, California (L.Z., A.S., H.-C.C., S.W.Y., K.M.G.); Pharmacokinetics and Drug Metabolism, Amgen Inc., Cambridge, Massachusetts (A.G.); Department of Pharmaceutics, School of Pharmacy, University of Washington, Seattle, Washington (B.P., L.W., J.D.U.); and Safety and ADME Translational Sciences, Drug Safety and Metabolism, IMED Biotech Unit, AstraZeneca, Cambridge, UK (S.H.S., K.S.F.)
| | - Sook Wah Yee
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, California (L.Z., A.S., H.-C.C., S.W.Y., K.M.G.); Pharmacokinetics and Drug Metabolism, Amgen Inc., Cambridge, Massachusetts (A.G.); Department of Pharmaceutics, School of Pharmacy, University of Washington, Seattle, Washington (B.P., L.W., J.D.U.); and Safety and ADME Translational Sciences, Drug Safety and Metabolism, IMED Biotech Unit, AstraZeneca, Cambridge, UK (S.H.S., K.S.F.)
| | - Li Wang
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, California (L.Z., A.S., H.-C.C., S.W.Y., K.M.G.); Pharmacokinetics and Drug Metabolism, Amgen Inc., Cambridge, Massachusetts (A.G.); Department of Pharmaceutics, School of Pharmacy, University of Washington, Seattle, Washington (B.P., L.W., J.D.U.); and Safety and ADME Translational Sciences, Drug Safety and Metabolism, IMED Biotech Unit, AstraZeneca, Cambridge, UK (S.H.S., K.S.F.)
| | - Jashvant D Unadkat
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, California (L.Z., A.S., H.-C.C., S.W.Y., K.M.G.); Pharmacokinetics and Drug Metabolism, Amgen Inc., Cambridge, Massachusetts (A.G.); Department of Pharmaceutics, School of Pharmacy, University of Washington, Seattle, Washington (B.P., L.W., J.D.U.); and Safety and ADME Translational Sciences, Drug Safety and Metabolism, IMED Biotech Unit, AstraZeneca, Cambridge, UK (S.H.S., K.S.F.)
| | - Simone H Stahl
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, California (L.Z., A.S., H.-C.C., S.W.Y., K.M.G.); Pharmacokinetics and Drug Metabolism, Amgen Inc., Cambridge, Massachusetts (A.G.); Department of Pharmaceutics, School of Pharmacy, University of Washington, Seattle, Washington (B.P., L.W., J.D.U.); and Safety and ADME Translational Sciences, Drug Safety and Metabolism, IMED Biotech Unit, AstraZeneca, Cambridge, UK (S.H.S., K.S.F.)
| | - Katherine S Fenner
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, California (L.Z., A.S., H.-C.C., S.W.Y., K.M.G.); Pharmacokinetics and Drug Metabolism, Amgen Inc., Cambridge, Massachusetts (A.G.); Department of Pharmaceutics, School of Pharmacy, University of Washington, Seattle, Washington (B.P., L.W., J.D.U.); and Safety and ADME Translational Sciences, Drug Safety and Metabolism, IMED Biotech Unit, AstraZeneca, Cambridge, UK (S.H.S., K.S.F.)
| | - Kathleen M Giacomini
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, California (L.Z., A.S., H.-C.C., S.W.Y., K.M.G.); Pharmacokinetics and Drug Metabolism, Amgen Inc., Cambridge, Massachusetts (A.G.); Department of Pharmaceutics, School of Pharmacy, University of Washington, Seattle, Washington (B.P., L.W., J.D.U.); and Safety and ADME Translational Sciences, Drug Safety and Metabolism, IMED Biotech Unit, AstraZeneca, Cambridge, UK (S.H.S., K.S.F.)
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5
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Hong M. Biochemical studies on the structure-function relationship of major drug transporters in the ATP-binding cassette family and solute carrier family. Adv Drug Deliv Rev 2017; 116:3-20. [PMID: 27317853 DOI: 10.1016/j.addr.2016.06.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Revised: 05/27/2016] [Accepted: 06/08/2016] [Indexed: 12/21/2022]
Abstract
Human drug transporters often play key roles in determining drug accumulation within cells. Their activities are often directly related to therapeutic efficacy, drug toxicity as well as drug-drug interactions. However, the progress for interpretation of their crystal structures is relatively slow. Hence, conventional biochemical studies together with computer modeling became useful manners to reveal essential structures of these membrane proteins. Over the years, quite a few structure-function relationship information had been obtained for members of the two major transporter families: the ATP-binding cassette family and the solute carrier family. Critical structural features of drug transporters include transmembrane domains, post-translational modification sites and domains for cell surface assembly and protein-protein interactions. Alterations at these important sites may affect protein stability, trafficking to the plasma membrane and/or ability of transporters to interact with substrates.
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6
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Langó T, Róna G, Hunyadi-Gulyás É, Turiák L, Varga J, Dobson L, Várady G, Drahos L, Vértessy BG, Medzihradszky KF, Szakács G, Tusnády GE. Identification of Extracellular Segments by Mass Spectrometry Improves Topology Prediction of Transmembrane Proteins. Sci Rep 2017; 7:42610. [PMID: 28211907 PMCID: PMC5304180 DOI: 10.1038/srep42610] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Accepted: 01/11/2017] [Indexed: 01/17/2023] Open
Abstract
Transmembrane proteins play crucial role in signaling, ion transport, nutrient uptake, as well as in maintaining the dynamic equilibrium between the internal and external environment of cells. Despite their important biological functions and abundance, less than 2% of all determined structures are transmembrane proteins. Given the persisting technical difficulties associated with high resolution structure determination of transmembrane proteins, additional methods, including computational and experimental techniques remain vital in promoting our understanding of their topologies, 3D structures, functions and interactions. Here we report a method for the high-throughput determination of extracellular segments of transmembrane proteins based on the identification of surface labeled and biotin captured peptide fragments by LC/MS/MS. We show that reliable identification of extracellular protein segments increases the accuracy and reliability of existing topology prediction algorithms. Using the experimental topology data as constraints, our improved prediction tool provides accurate and reliable topology models for hundreds of human transmembrane proteins.
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Affiliation(s)
- Tamás Langó
- Institute of Enzymology, RCNS, Hungarian Academy of Sciences, Magyar Tudósok krt 2, Budapest, H-1117 Hungary
| | - Gergely Róna
- Institute of Enzymology, RCNS, Hungarian Academy of Sciences, Magyar Tudósok krt 2, Budapest, H-1117 Hungary.,Department of Applied Biotechnology and Food Sciences, Budapest University of Technology and Economics, Szent Gellért tér 4, Budapest, H-1111, Hungary.,Department of Biochemistry and Molecular Pharmacology, Perlmutter NYU Cancer Center, New York University School of Medicine, 522 First Avenue, SRB 1107, New York, NY 10016, USA
| | - Éva Hunyadi-Gulyás
- Laboratory of Proteomics Research, Biological Research Center of the Hungarian Academy of Sciences, Temesvari krt. 62, Szeged, H-6726, Hungary
| | - Lilla Turiák
- Institute of Organic Chemistry, RCNS, Hungarian Academy of Sciences, Magyar Tudósok krt 2, Budapest, H-1117 Hungary
| | - Julia Varga
- Institute of Enzymology, RCNS, Hungarian Academy of Sciences, Magyar Tudósok krt 2, Budapest, H-1117 Hungary
| | - László Dobson
- Institute of Enzymology, RCNS, Hungarian Academy of Sciences, Magyar Tudósok krt 2, Budapest, H-1117 Hungary
| | - György Várady
- Institute of Enzymology, RCNS, Hungarian Academy of Sciences, Magyar Tudósok krt 2, Budapest, H-1117 Hungary
| | - László Drahos
- Institute of Organic Chemistry, RCNS, Hungarian Academy of Sciences, Magyar Tudósok krt 2, Budapest, H-1117 Hungary
| | - Beáta G Vértessy
- Institute of Enzymology, RCNS, Hungarian Academy of Sciences, Magyar Tudósok krt 2, Budapest, H-1117 Hungary.,Department of Applied Biotechnology and Food Sciences, Budapest University of Technology and Economics, Szent Gellért tér 4, Budapest, H-1111, Hungary
| | - Katalin F Medzihradszky
- Laboratory of Proteomics Research, Biological Research Center of the Hungarian Academy of Sciences, Temesvari krt. 62, Szeged, H-6726, Hungary
| | - Gergely Szakács
- Institute of Enzymology, RCNS, Hungarian Academy of Sciences, Magyar Tudósok krt 2, Budapest, H-1117 Hungary
| | - Gábor E Tusnády
- Institute of Enzymology, RCNS, Hungarian Academy of Sciences, Magyar Tudósok krt 2, Budapest, H-1117 Hungary
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7
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Xu D, Wang H, You G. Posttranslational Regulation of Organic Anion Transporters by Ubiquitination: Known and Novel. Med Res Rev 2016; 36:964-79. [PMID: 27291023 DOI: 10.1002/med.21397] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Revised: 04/27/2016] [Accepted: 04/27/2016] [Indexed: 12/25/2022]
Abstract
Organic anion transporters (OATs) encoded by solute carrier 22 family are localized in the epithelia of multiple organs, where they mediate the absorption, distribution, and excretion of a diverse array of negatively charged environmental toxins and clinically important drugs. Alterations in the expression and function of OATs play important roles in intra- and interindividual variability of the therapeutic efficacy and the toxicity of many drugs. As a result, the activity of OATs must be under tight regulation so as to carry out their normal functions. The regulation of OAT transport activity in response to various stimuli can occur at several levels such as transcription, translation, and posttranslational modification. Posttranslational regulation is of particular interest, because it usually happens within a very short period of time (minutes to hours) when the body has to deal with rapidly changing amounts of substances as a consequence of variable intake of drugs, fluids, or meals as well as metabolic activity. This review article highlights the recent advances from our laboratory in uncovering several posttranslational mechanisms underlying OAT regulation. These advances offer the promise of identifying targets for novel strategies that will maximize therapeutic efficacy in drug development.
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Affiliation(s)
- Da Xu
- Department of Pharmaceutics, Rutgers University, Piscataway, New Jersey, 08854
| | - Haoxun Wang
- Department of Pharmaceutics, Rutgers University, Piscataway, New Jersey, 08854
| | - Guofeng You
- Department of Pharmaceutics, Rutgers University, Piscataway, New Jersey, 08854
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8
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Roth M, Obaidat A, Hagenbuch B. OATPs, OATs and OCTs: the organic anion and cation transporters of the SLCO and SLC22A gene superfamilies. Br J Pharmacol 2012; 165:1260-87. [PMID: 22013971 DOI: 10.1111/j.1476-5381.2011.01724.x] [Citation(s) in RCA: 553] [Impact Index Per Article: 46.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The human organic anion and cation transporters are classified within two SLC superfamilies. Superfamily SLCO (formerly SLC21A) consists of organic anion transporting polypeptides (OATPs), while the organic anion transporters (OATs) and the organic cation transporters (OCTs) are classified in the SLC22A superfamily. Individual members of each superfamily are expressed in essentially every epithelium throughout the body, where they play a significant role in drug absorption, distribution and elimination. Substrates of OATPs are mainly large hydrophobic organic anions, while OATs transport smaller and more hydrophilic organic anions and OCTs transport organic cations. In addition to endogenous substrates, such as steroids, hormones and neurotransmitters, numerous drugs and other xenobiotics are transported by these proteins, including statins, antivirals, antibiotics and anticancer drugs. Expression of OATPs, OATs and OCTs can be regulated at the protein or transcriptional level and appears to vary within each family by both protein and tissue type. All three superfamilies consist of 12 transmembrane domain proteins that have intracellular termini. Although no crystal structures have yet been determined, combinations of homology modelling and mutation experiments have been used to explore the mechanism of substrate recognition and transport. Several polymorphisms identified in members of these superfamilies have been shown to affect pharmacokinetics of their drug substrates, confirming the importance of these drug transporters for efficient pharmacological therapy. This review, unlike other reviews that focus on a single transporter family, briefly summarizes the current knowledge of all the functionally characterized human organic anion and cation drug uptake transporters of the SLCO and the SLC22A superfamilies.
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Affiliation(s)
- Megan Roth
- Department of Pharmacology, Toxicology and Therapeutics, The University of Kansas Medical Center, Kansas City, KS 66160, USA
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9
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Emami Riedmaier A, Nies AT, Schaeffeler E, Schwab M. Organic Anion Transporters and Their Implications in Pharmacotherapy. Pharmacol Rev 2012; 64:421-49. [DOI: 10.1124/pr.111.004614] [Citation(s) in RCA: 91] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
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10
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Burckhardt G, Burckhardt BC. In vitro and in vivo evidence of the importance of organic anion transporters (OATs) in drug therapy. Handb Exp Pharmacol 2011:29-104. [PMID: 21103968 DOI: 10.1007/978-3-642-14541-4_2] [Citation(s) in RCA: 136] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Organic anion transporters 1-10 (OAT1-10) and the urate transporter 1 (URAT1) belong to the SLC22A gene family and accept a huge variety of chemically unrelated endogenous and exogenous organic anions including many frequently described drugs. OAT1 and OAT3 are located in the basolateral membrane of renal proximal tubule cells and are responsible for drug uptake from the blood into the cells. OAT4 in the apical membrane of human proximal tubule cells is related to drug exit into the lumen and to uptake of estrone sulfate and urate from the lumen into the cell. URAT1 is the major urate-absorbing transporter in the apical membrane and is a target for uricosuric drugs. OAT10, also located in the luminal membrane, transports nicotinate with high affinity and interacts with drugs. Major extrarenal locations of OATs include the blood-brain barrier for OAT3, the placenta for OAT4, the nasal epithelium for OAT6, and the liver for OAT2 and OAT7. For all transporters we provide information on cloning, tissue distribution, factors influencing OAT abundance, interaction with endogenous compounds and different drug classes, drug/drug interactions and, if known, single nucleotide polymorphisms.
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Affiliation(s)
- Gerhard Burckhardt
- Abteilung Vegetative Physiologie und Pathophysiologie, Zentrum Physiologie und Pathophysiologie, Göttingen, Germany.
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11
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Srimaroeng C, Perry JL, Pritchard JB. Physiology, structure, and regulation of the cloned organic anion transporters. Xenobiotica 2008; 38:889-935. [PMID: 18668434 DOI: 10.1080/00498250801927435] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
1. The transport of negatively charged drugs, xenobiotics, and metabolites by epithelial tissues, particularly the kidney, plays critical roles in controlling their distribution, concentration, and retention in the body. Thus, organic anion transporters (OATs) impact both their therapeutic efficacy and potential toxicity. 2. This review summarizes current knowledge of the properties and functional roles of the cloned OATs, the relationships between transporter structure and function, and those factors that determine the efficacy of transport. Such factors include plasma protein binding of substrates, genetic polymorphisms among the transporters, and regulation of transporter expression. 3. Clearly, much progress has been made in the decade since the first OAT was cloned. However, unresolved questions remain. Several of these issues--drug-drug interactions, functional characterization of newly cloned OATs, tissue differences in expression and function, and details of the nature and consequences of transporter regulation at genomic and intracellular sites--are discussed in the concluding Perspectives section.
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Affiliation(s)
- C Srimaroeng
- Laboratory of Pharmacology, Environmental Toxicology Program, National Institute of Environmental Health Sciences, NC 27709, USA
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12
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Selcuk Unal E, Zhao R, Qiu A, Goldman ID. N-linked glycosylation and its impact on the electrophoretic mobility and function of the human proton-coupled folate transporter (HsPCFT). BIOCHIMICA ET BIOPHYSICA ACTA 2008; 1778:1407-14. [PMID: 18405659 PMCID: PMC2762823 DOI: 10.1016/j.bbamem.2008.03.009] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/19/2007] [Revised: 03/07/2008] [Accepted: 03/07/2008] [Indexed: 01/26/2023]
Abstract
The human proton-coupled folate transporter (HsPCFT, SLC46A1) mediates intestinal absorption of folates and transport of folates into the liver, brain and other tissues. On Western blot, HsPCFT migrates as a broad band (~55 kDa), higher than predicted (~50 kDa) in cell lines. Western blot analysis required that membrane preparations not be incubated in the loading buffer above 50 degrees C to avoid aggregation of the protein. Treatment of membrane fractions from HsPCFT-transfected HeLa cells with peptidyl N-glycanase F, or cells with tunicamycin, resulted in conversion to a ~35 kDa species. Substitution of asparagine residues of two canonical glycosylation sites to glutamine, individually, yielded a ~47 kDa protein; substitution of both sites gave a smaller (~35 kDa) protein. Single mutants retained full transport activity; the double mutant retained a majority of activity. Transport function and molecular size were unchanged when the double mutant was hemagglutinin (HA) tagged at either the NH(2) or COOH terminus and probed with an anti-HA antibody excluding degradation of the deglycosylated protein. Wild-type or deglycosylated HsPCFT HA, tagged at amino or carboxyl termini, could only be visualized on the plasma membrane when HeLa cells were first permeabilized, consistent with the intracellular location of these domains.
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Key Words
- rfc, reduced folate carrier
- pcft, proton-coupled folate transporter
- slc, solute carrier family
- tmds, transmembrane domains
- pngasef, peptide-n4-(n-acetyl-β-d-glucosaminyl)asparagine amidase f
- endo h, endo-β-n-acetylglucosaminidase h
- mtx, methotrexate
- dtt, dithiothreitol
- sds-page, sodium dodecyl sulfate polyacrylamide gel electrophoresis
- omim, online mendelian inheritance in man
- hcp1
- pcft/hcp1
- pcft glycosylation
- folate transport
- intestinal folate absorption
- pcft secondary structure
- hereditary folate malabsorption (hfm)
- slc46a1
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Affiliation(s)
- Ersin Selcuk Unal
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA
| | - Rongbao Zhao
- Department of Medicine, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA,Department of Molecular Pharmacology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA
| | - Andong Qiu
- Department of Medicine, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA,Department of Molecular Pharmacology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA
| | - I. David Goldman
- Department of Medicine, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA,Department of Molecular Pharmacology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA,Corresponding author. Cancer Center, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA
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Rizwan AN, Krick W, Burckhardt G. The chloride dependence of the human organic anion transporter 1 (hOAT1) is blunted by mutation of a single amino acid. J Biol Chem 2007; 282:13402-9. [PMID: 17353191 DOI: 10.1074/jbc.m609849200] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Organic anion transporter 1 (OAT1) is key for the secretion of organic anions in renal proximal tubules. These organic anions comprise endogenous as well as exogenous compounds including frequently used drugs of various chemical structures. The molecular basis for the polyspecificity of OAT1 is not known. Here we mutated a conserved positively charged arginine residue (Arg(466)) in the 11(th) transmembrane helix of human OAT1. The replacement by the positively charged lysine (R466K) did not impair expression of hOAT1 at the plasma membrane of Xenopus laevis oocytes but decreased the transport of p-aminohippurate (PAH) considerably. Extracellular glutarate inhibited and intracellular glutarate trans-stimulated wild type and mutated OAT1, suggesting for the mutant R466K an unimpaired interaction with dicarboxylates. However, when Arg(466) was replaced by the negatively charged aspartate (R466D), glutarate no longer interacted with the mutant. PAH uptake by wild type hOAT1 was stimulated in the presence of chloride, whereas the R466K mutant was chloride-insensitive. Likewise, the uptake of labeled glutarate or ochratoxin A was chloride-dependent in the wild type but not in R466K. Kinetic experiments revealed that chloride did not alter the apparent K(m) for PAH but influenced V(max) in wild type OAT1-expressing oocytes. In R466K mutants the apparent K(m) for PAH was similar to that of the wild type, but V(max) was not changed by chloride removal. We conclude that Arg(466) influences the binding of glutarate, but not interaction with PAH, and interacts with chloride, which is a major determinant in substrate translocation.
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Affiliation(s)
- Ahsan N Rizwan
- Abteilung Vegetative Physiologie und Pathophysiologie, Zentrum Physiologie und Pathophysiologie, Georg-August-Universität Göttingen, Humboldtallee 23, 37073 Göttingen, Germany
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