1
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Kataoka H, Akiyoshi T, Uchida Y, Imaoka A, Terasaki T, Ohtani H. The Effects of N-Glycosylation on the Expression and Transport Activity of OATP1A2 and OATP2B1. J Pharm Sci 2024; 113:1376-1384. [PMID: 38432624 DOI: 10.1016/j.xphs.2024.02.012] [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: 12/22/2023] [Revised: 02/12/2024] [Accepted: 02/13/2024] [Indexed: 03/05/2024]
Abstract
Organic anion transporting polypeptide (OATP)1A2 and OATP2B1 have potential N-glycosylation sites, but their influence remains unclear. This study aimed to identify the N-glycosylation sites of OATP1A2/2B1 and investigate their impact on the expression and function of OATP1A2/2B1. Human embryonic kidney cells expressing OATP1A2 or OATP2B1 (HEK293-OATP1A2/2B1) were exposed to tunicamycin, an N-glycosylation inhibitor, and a plasma membrane fraction (PMF) Western blot assay and an estrone 3-sulfate (E3S) uptake study were conducted. HEK293-OATP1A2/OATP2B1 cell lines with mutation(s) at potential N-glycosylation sites were established, and the Western blotting and uptake study were repeated. Tunicamycin reduced the PMF levels and E3S uptake of OATP1A2/OATP2B1. The Asn124Gln, Asn135Gln, and Asn492Gln mutations in OATP1A2 and Asn176Gln and Asn538Gln mutations in OATP2B1 reduced the molecular weights of the OATP molecules and their PMF levels. The PMF levels of OATP1A2 Asn124/135Gln, OATP1A2 Asn124/135/492Gln, and OATP2B1 Asn176/538Gln were further reduced. The maximum transport velocities of OATP1A2 Asn124Gln, OATP1A2 Asn135Gln, and OATP2B1 Asn176/538Gln were markedly reduced to 10 %, 4 %, and 10 % of the wild-type level, respectively. In conclusion, the N-glycans at Asn124 and Asn135 of OATP1A2 and those at Asn176 and Asn538 of OATP2B1 are essential for the plasma membrane expression of these molecules and also affect their transport function.
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Affiliation(s)
- Hiroki Kataoka
- Division of Clinical Pharmacy, Graduate School of Pharmaceutical Sciences, Keio University, 1-5-30, Shibakoen, Minato-ku, Tokyo 105-8512, Japan
| | - Takeshi Akiyoshi
- Division of Clinical Pharmacy, Graduate School of Pharmaceutical Sciences, Keio University, 1-5-30, Shibakoen, Minato-ku, Tokyo 105-8512, Japan; Department of Clinical Pharmacy, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan
| | - Yasuo Uchida
- Graduate School of Biomedical and Health Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima city 734-0037, Japan
| | - Ayuko Imaoka
- Division of Clinical Pharmacy, Graduate School of Pharmaceutical Sciences, Keio University, 1-5-30, Shibakoen, Minato-ku, Tokyo 105-8512, Japan
| | - Tetsuya Terasaki
- School of Pharmacy, University of Eastern Finland, Yliopistonranta 1 C, 70211 Kuopio, Finland
| | - Hisakazu Ohtani
- Division of Clinical Pharmacy, Graduate School of Pharmaceutical Sciences, Keio University, 1-5-30, Shibakoen, Minato-ku, Tokyo 105-8512, Japan; Department of Clinical Pharmacy, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan; Department of Pharmacy, Keio University Hospital, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan.
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2
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Wang P, Murray JW, Wolkoff AW. Interaction of Human OATP1B1 with PDZK1 Is Required for Its Trafficking to the Hepatocyte Plasma Membrane. Drug Metab Dispos 2023; 51:1342-1349. [PMID: 37442606 PMCID: PMC10506696 DOI: 10.1124/dmd.123.001248] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Revised: 07/03/2023] [Accepted: 07/07/2023] [Indexed: 07/15/2023] Open
Abstract
Uptake of xenobiotics by hepatocytes is mediated by specific proteins, including organic anion transporting polypeptides (OATPs), residing on the basolateral (sinusoidal) plasma membrane. Many of the OATPs have PDZ consensus binding sites, determined by their C-terminal 4 amino acids, while others do not. Mouse and rat OATP1A1 are associated with PDZK1, which is necessary for their trafficking to the plasma membrane. humanOATP1B1 (hOATP1B1) is a major drug transporter in human liver. Although localized to the plasma membrane, it was thought to lack a PDZ consensus motif, suggesting that the trafficking paradigm for murine OATPs is not applicable to human liver. The aim of the present study was to determine whether hOATP1B1 is a ligand for hPDZK1. hOATP1B1 immunoprecipitates with hPDZK1 following co-expression in 293T cells as well as in normal human liver. Co-expression with each of the 4 PDZ domains revealed interaction with domain 1 only. A truncated version of hOATP1B1 that lacks its terminal 4 amino acid PDZ binding motif as well as hOATP1B3, which does not contain a PDZ binding consensus motif, failed to interact with hPDZK1. Immunofluorescence microscopy of hOATP1B1 in stably transfected HeLa cells that endogenously express hPDZK1 showed that it distributes predominantly along the plasma membrane whereas hOATP1B1 lacking its terminal 4 amino acids distributes primarily intracellularly with little plasma membrane localization. Similar to findings in rats and mice, human OATP1B1 is a ligand for PDZK1 and requires interaction with PDZK1 for optimal trafficking to the hepatocyte plasma membrane. SIGNIFICANCE: Previous studies suggested that OATP1B1, a major xenobiotic transporter in human liver, does not have a PDZ binding consensus motif and does not follow the paradigm for subcellular trafficking and function that was established for OATP1A1 in murine liver. We now demonstrated that OATP1B1 but not OATP1B3 has a PDZ binding consensus motif that mediates binding to PDZK1 and is required for its trafficking to the plasma membrane. Such interaction could be an important previously unrecognized modulator of transport function.
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Affiliation(s)
- Pijun Wang
- Marion Bessin Liver Research Center (P.W., J.W.M., A.W.W.), Department of Developmental and Molecular Biology (J.W.M., A.W.W.), and Division of Hepatology (A.W.W.), Albert Einstein College of Medicine and Montefiore Medical Center, Bronx, New York
| | - John W Murray
- Marion Bessin Liver Research Center (P.W., J.W.M., A.W.W.), Department of Developmental and Molecular Biology (J.W.M., A.W.W.), and Division of Hepatology (A.W.W.), Albert Einstein College of Medicine and Montefiore Medical Center, Bronx, New York
| | - Allan W Wolkoff
- Marion Bessin Liver Research Center (P.W., J.W.M., A.W.W.), Department of Developmental and Molecular Biology (J.W.M., A.W.W.), and Division of Hepatology (A.W.W.), Albert Einstein College of Medicine and Montefiore Medical Center, Bronx, New York
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3
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Nakamura Y, Aizawa C, Kawata H, Nakanishi T. N-glycosylation modifies prostaglandin E 2 uptake by reducing cell surface expression of SLCO2A1. Prostaglandins Other Lipid Mediat 2023; 165:106714. [PMID: 36706979 DOI: 10.1016/j.prostaglandins.2023.106714] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Revised: 01/10/2023] [Accepted: 01/23/2023] [Indexed: 01/26/2023]
Abstract
SLCO2A1 functions as a prostaglandin (PG) influx transporter to facilitate intracellular oxidation of PGs and its defect causes dysregulation of PG signaling and metabolism. This study aimed to clarify effects of N-glycosylation on functional SLCO2A1 expression. Putative N-glycosylation site(s) (N134, N478, and/or N491) of human SLCO2A1 were mutated to Q and wild-type (WT) and mutant forms were expressed in HEK293 and human epithelial cells. Molecular weight of WT decreased to nearly 55 kDa by PNGase F treatment and was identical to that of triple mutant (TM, i.e., N134Q/N478Q/N491Q). Transport affinity of TM for PGE2 (Km of 392.7 nM) was comparable to that of WT (Km of 328.5 nM); however, immunoassays showed that TM cell surface expression remained at 24% of WT in HEK293 cells, resulting in a reduced cellular PGE2 uptake. These results suggest N-glycosylation modifies cellular PGE2 uptake by decreasing SLCO2A1 localization to the plasma membrane.
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Affiliation(s)
- Yoshinobu Nakamura
- Laboratory of Membrane Transport for Biopharmaceutics, Faculty of Pharmacy, Takasaki University of Health and Welfare, Takasaki, Japan
| | - Chisato Aizawa
- Laboratory of Membrane Transport for Biopharmaceutics, Faculty of Pharmacy, Takasaki University of Health and Welfare, Takasaki, Japan
| | - Hinako Kawata
- Laboratory of Membrane Transport for Biopharmaceutics, Faculty of Pharmacy, Takasaki University of Health and Welfare, Takasaki, Japan
| | - Takeo Nakanishi
- Laboratory of Membrane Transport for Biopharmaceutics, Faculty of Pharmacy, Takasaki University of Health and Welfare, Takasaki, Japan.
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4
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Wang Z, Li Y, Villanueva CE, Peng T, Han W, Bo Z, Zhang H, Hagenbuch B, Gui C. The Importance of Val386 in Transmembrane Domain 8 for the Activation of OATP1B3 by Epigallocatechin Gallate. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2022; 70:6552-6560. [PMID: 35603894 PMCID: PMC9438777 DOI: 10.1021/acs.jafc.2c02692] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Estrone-3-sulfate (E3S) uptake mediated by organic anion transporting polypeptide 1B3 (OATP1B3) can be activated by epigallocatechin gallate (EGCG). In this study, by using chimeric transporters and site-directed mutagenesis, we found that Val386 in transmembrane domain 8 (TM8) is essential for OATP1B3's activation by EGCG. Kinetic studies showed that the loss of activation of 1B3-TM8 and 1B3-V386F in the presence of EGCG is due to their decreased substrate binding affinity and reduced maximal transport rate. The overall transport efficiencies of OATP1B3, 1B3-TM8, and 1B3-V386F in the absence and presence of EGCG are 8.6 ± 0.7 vs 15.9 ± 1.4 (p < 0.05), 11.2 ± 2.1 vs 2.7 ± 0.3 (p < 0.05), and 10.2 ± 1.0 vs 2.5 ± 0.3 (p < 0.05), respectively. While 1B3-V386F cannot be activated by EGCG, its transport activity for EGCG is also diminished. OATP1B3's activation by EGCG is substrate-dependent as EGCG inhibits OATP1B3-mediated pravastatin uptake. Furthermore, the activation of OATP1B3-mediated E3S uptake by quercetin 3-O-α-l-arabinopyranosyl(1 → 2)-α-l-rhamnopyranoside is not affected by TM8 and V386F. Taken together, the activation of OATP1B3 by small molecules is substrate- and modulator-dependent, and V386 in TM8 plays a critical role in the activation of OATP1B3-mediated E3S uptake by EGCG.
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Affiliation(s)
- Zhongmin Wang
- College of Pharmaceutical Sciences, Soochow University, 199 Renai Road, Suzhou Industrial Park, Suzhou, Jiangsu 215123, People’s Republic of China
| | - Ying Li
- College of Pharmaceutical Sciences, Soochow University, 199 Renai Road, Suzhou Industrial Park, Suzhou, Jiangsu 215123, People’s Republic of China
| | - Cecilia E. Villanueva
- Department of Pharmacology, Toxicology and Therapeutics, the University of Kansas Medical Center, 3901 Rainbow Boulevard, Kansas City, Kansas 66160, United States
| | - Taotao Peng
- College of Pharmaceutical Sciences, Soochow University, 199 Renai Road, Suzhou Industrial Park, Suzhou, Jiangsu 215123, People’s Republic of China
| | - Wanjun Han
- College of Pharmaceutical Sciences, Soochow University, 199 Renai Road, Suzhou Industrial Park, Suzhou, Jiangsu 215123, People’s Republic of China
| | - Zheyue Bo
- College of Pharmaceutical Sciences, Soochow University, 199 Renai Road, Suzhou Industrial Park, Suzhou, Jiangsu 215123, People’s Republic of China
| | - Hongjian Zhang
- College of Pharmaceutical Sciences, Soochow University, 199 Renai Road, Suzhou Industrial Park, Suzhou, Jiangsu 215123, People’s Republic of China
| | - Bruno Hagenbuch
- Department of Pharmacology, Toxicology and Therapeutics, the University of Kansas Medical Center, 3901 Rainbow Boulevard, Kansas City, Kansas 66160, United States
| | - Chunshan Gui
- College of Pharmaceutical Sciences, Soochow University, 199 Renai Road, Suzhou Industrial Park, Suzhou, Jiangsu 215123, People’s Republic of China
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5
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The Interplay between Uremic Toxins and Albumin, Membrane Transporters and Drug Interaction. Toxins (Basel) 2022; 14:toxins14030177. [PMID: 35324674 PMCID: PMC8949274 DOI: 10.3390/toxins14030177] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 02/21/2022] [Accepted: 02/24/2022] [Indexed: 01/10/2023] Open
Abstract
Uremic toxins are a heterogeneous group of molecules that accumulate in the body due to the progression of chronic kidney disease (CKD). These toxins are associated with kidney dysfunction and the development of comorbidities in patients with CKD, being only partially eliminated by dialysis therapies. Importantly, drugs used in clinical treatments may affect the levels of uremic toxins, their tissue disposition, and even their elimination through the interaction of both with proteins such as albumin and cell membrane transporters. In this context, protein-bound uremic toxins (PBUTs) are highlighted for their high affinity for albumin, the most abundant serum protein with multiple binding sites and an ability to interact with drugs. Membrane transporters mediate the cellular influx and efflux of various uremic toxins, which may also compete with drugs as substrates, and both may alter transporter activity or expression. Therefore, this review explores the interaction mechanisms between uremic toxins and albumin, as well as membrane transporters, considering their potential relationship with drugs used in clinical practice.
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6
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TAN D, CUI J, QIN L, CHEN L, WANG Y, ZHANG Q, HE Y. The role of OATP1A1 in cholestasis and drug-induced toxicity: a systematic review. FOOD SCIENCE AND TECHNOLOGY 2022. [DOI: 10.1590/fst.70722] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
| | - Jinguo CUI
- Baodi Clinical College of Tianjin Medical University, China
| | - Lin QIN
- Zunyi Medical University, China
| | - Li CHEN
- Zunyi Medical University, China
| | - Yuhe WANG
- Affiliated Hospital of Zunyi Medical University, China
| | | | - Yuqi HE
- Zunyi Medical University, China
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7
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Tuerkova A, Ungvári O, Laczkó-Rigó R, Mernyák E, Szakács G, Özvegy-Laczka C, Zdrazil B. Data-Driven Ensemble Docking to Map Molecular Interactions of Steroid Analogs with Hepatic Organic Anion Transporting Polypeptides. J Chem Inf Model 2021; 61:3109-3127. [PMID: 34105971 PMCID: PMC8243326 DOI: 10.1021/acs.jcim.1c00362] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
![]()
Hepatic organic anion transporting polypeptides—OATP1B1,
OATP1B3, and OATP2B1—are expressed at the basolateral membrane
of hepatocytes, being responsible for the uptake of a wide range of
natural substrates and structurally unrelated pharmaceuticals. Impaired
function of hepatic OATPs has been linked to clinically relevant drug–drug
interactions leading to altered pharmacokinetics of administered drugs.
Therefore, understanding the commonalities and differences across
the three transporters represents useful knowledge to guide the drug
discovery process at an early stage. Unfortunately, such efforts remain
challenging because of the lack of experimentally resolved protein
structures for any member of the OATP family. In this study, we established
a rigorous computational protocol to generate and validate structural
models for hepatic OATPs. The multistep procedure is based on the
systematic exploration of available protein structures with shared
protein folding using normal-mode analysis, the calculation of multiple
template backbones from elastic network models, the utilization of
multiple template conformations to generate OATP structural models
with various degrees of conformational flexibility, and the prioritization
of models on the basis of enrichment docking. We employed the resulting
OATP models of OATP1B1, OATP1B3, and OATP2B1 to elucidate binding
modes of steroid analogs in the three transporters. Steroid conjugates
have been recognized as endogenous substrates of these transporters.
Thus, investigating this data set delivers insights into mechanisms
of substrate recognition. In silico predictions were complemented
with in vitro studies measuring the bioactivity of a compound set
on OATP expressing cell lines. Important structural determinants conferring
shared and distinct binding patterns of steroid analogs in the three
transporters have been identified. Overall, this comparative study
provides novel insights into hepatic OATP-ligand interactions and
selectivity. Furthermore, the integrative computational workflow for
structure-based modeling can be leveraged for other pharmaceutical
targets of interest.
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Affiliation(s)
- Alzbeta Tuerkova
- University of Vienna, Department of Pharmaceutical Sciences, Division of Pharmaceutical Chemistry, Althanstraße 14, A-1090 Vienna, Austria
| | - Orsolya Ungvári
- Drug Resistance Research Group, Institute of Enzymology, RCNS, Eötvös Loránd Research Network, H-1117, Budapest, Magyar tudósok krt. 2, Hungary
| | - Réka Laczkó-Rigó
- Drug Resistance Research Group, Institute of Enzymology, RCNS, Eötvös Loránd Research Network, H-1117, Budapest, Magyar tudósok krt. 2, Hungary
| | - Erzsébet Mernyák
- Department of Organic Chemistry, University of Szeged, Dóm tér 8, H-6720 Szeged, Hungary
| | - Gergely Szakács
- Drug Resistance Research Group, Institute of Enzymology, RCNS, Eötvös Loránd Research Network, H-1117, Budapest, Magyar tudósok krt. 2, Hungary.,Department of Medicine I, Institute of Cancer Research, Comprehensive Cancer Center, Medical University of Vienna, A-1090 Vienna, Austria
| | - Csilla Özvegy-Laczka
- Drug Resistance Research Group, Institute of Enzymology, RCNS, Eötvös Loránd Research Network, H-1117, Budapest, Magyar tudósok krt. 2, Hungary
| | - Barbara Zdrazil
- University of Vienna, Department of Pharmaceutical Sciences, Division of Pharmaceutical Chemistry, Althanstraße 14, A-1090 Vienna, Austria
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8
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Groeneweg S, van Geest FS, Peeters RP, Heuer H, Visser WE. Thyroid Hormone Transporters. Endocr Rev 2020; 41:5637505. [PMID: 31754699 DOI: 10.1210/endrev/bnz008] [Citation(s) in RCA: 102] [Impact Index Per Article: 25.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Accepted: 11/07/2019] [Indexed: 02/08/2023]
Abstract
Thyroid hormone transporters at the plasma membrane govern intracellular bioavailability of thyroid hormone. Monocarboxylate transporter (MCT) 8 and MCT10, organic anion transporting polypeptide (OATP) 1C1, and SLC17A4 are currently known as transporters displaying the highest specificity toward thyroid hormones. Structure-function studies using homology modeling and mutational screens have led to better understanding of the molecular basis of thyroid hormone transport. Mutations in MCT8 and in OATP1C1 have been associated with clinical disorders. Different animal models have provided insight into the functional role of thyroid hormone transporters, in particular MCT8. Different treatment strategies for MCT8 deficiency have been explored, of which thyroid hormone analogue therapy is currently applied in patients. Future studies may reveal the identity of as-yet-undiscovered thyroid hormone transporters. Complementary studies employing animal and human models will provide further insight into the role of transporters in health and disease. (Endocrine Reviews 41: 1 - 55, 2020).
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Affiliation(s)
- Stefan Groeneweg
- Department of Internal Medicine, Erasmus Medical Center, Rotterdam, the Netherlands Academic Center for Thyroid Diseases, Erasmus Medical Center, Rotterdam, the Netherlands
| | - Ferdy S van Geest
- Department of Internal Medicine, Erasmus Medical Center, Rotterdam, the Netherlands Academic Center for Thyroid Diseases, Erasmus Medical Center, Rotterdam, the Netherlands
| | - Robin P Peeters
- Department of Internal Medicine, Erasmus Medical Center, Rotterdam, the Netherlands Academic Center for Thyroid Diseases, Erasmus Medical Center, Rotterdam, the Netherlands
| | - Heike Heuer
- Department of Endocrinology, Diabetes and Metabolism, University Hospital Essen, University Duisburg-Essen, Essen, Germany
| | - W Edward Visser
- Department of Internal Medicine, Erasmus Medical Center, Rotterdam, the Netherlands Academic Center for Thyroid Diseases, Erasmus Medical Center, Rotterdam, the Netherlands
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9
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Taniguchi T, Zanetti-Yabur A, Wang P, Usyk M, Burk RD, Wolkoff AW. Interindividual Diversity in Expression of Organic Anion Uptake Transporters in Normal and Cirrhotic Human Liver. Hepatol Commun 2020; 4:739-752. [PMID: 32363323 PMCID: PMC7193130 DOI: 10.1002/hep4.1489] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Accepted: 01/23/2020] [Indexed: 12/12/2022] Open
Abstract
The liver plays an essential role in removing endogenous and exogenous compounds from the circulation. This function is mediated by specific transporters, including members of the family of organic anion transport proteins (OATPs) and the Na+-taurocholate transporting polypeptide (NTCP). In the present study, transporter protein expression was determined in liver samples from patients with cirrhosis or controls without liver disease. Five transporters (OATP1A2, OATP1B1, OATP1B3, OATP2B1, and NTCP) were studied. Transporter content in homogenates of human liver was quantified on western blots probed with transporter-specific antibodies in which a calibrated green fluorescent protein-tagged transporter standard was included. Liver samples from 21 patients with cirrhosis (hepatitis C in 17 and alcohol abuse in 4) and 17 controls without liver disease were analyzed. Expression of each of the transporters had a large spread, varying by an order of magnitude in cirrhotic and control livers. OATP1B1 was the most abundant transporter in controls (P < 0.01) but was significantly lower in cirrhotic livers as was NTCP expression (P < 0.01). There was little difference in transporter expression with respect to age or sex. Despite the large variability in transporter expression within a group, analysis in individuals showed that those with high or low expression of one transporter had a similar magnitude in expression of the others. Conclusion: Differences in transporter expression could explain unanticipated heterogeneity of drug transport and metabolism in individuals with and without liver disease.
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Affiliation(s)
- Tatsuya Taniguchi
- Marion Bessin Liver Research Center Albert Einstein College of Medicine and Montefiore Medical Center Bronx NY.,Division of Hepatology Albert Einstein College of Medicine and Montefiore Medical Center Bronx NY
| | - Alana Zanetti-Yabur
- Marion Bessin Liver Research Center Albert Einstein College of Medicine and Montefiore Medical Center Bronx NY.,Division of Hepatology Albert Einstein College of Medicine and Montefiore Medical Center Bronx NY
| | - Pijun Wang
- Marion Bessin Liver Research Center Albert Einstein College of Medicine and Montefiore Medical Center Bronx NY.,Division of Hepatology Albert Einstein College of Medicine and Montefiore Medical Center Bronx NY
| | - Mykhaylo Usyk
- Department of Pediatrics Albert Einstein College of Medicine and Montefiore Medical Center Bronx NY
| | - Robert D Burk
- Department of Pediatrics Albert Einstein College of Medicine and Montefiore Medical Center Bronx NY.,Department of Epidemiology and Population Health Albert Einstein College of Medicine and Montefiore Medical Center Bronx NY.,Department of Microbiology and Immunology Albert Einstein College of Medicine and Montefiore Medical Center Bronx NY
| | - Allan W Wolkoff
- Marion Bessin Liver Research Center Albert Einstein College of Medicine and Montefiore Medical Center Bronx NY.,Division of Hepatology Albert Einstein College of Medicine and Montefiore Medical Center Bronx NY.,Department of Anatomy and Structural Biology Albert Einstein College of Medicine and Montefiore Medical Center Bronx NY
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10
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Wang P, Wang WJ, Choi-Nurvitadhi J, Lescaille Y, Murray JW, Wolkoff AW. Rat Organic Anion Transport Protein 1A1 Interacts Directly With Organic Anion Transport Protein 1A4 Facilitating Its Maturation and Trafficking to the Hepatocyte Plasma Membrane. Hepatology 2019; 70:2156-2170. [PMID: 31102415 PMCID: PMC6859187 DOI: 10.1002/hep.30772] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Accepted: 05/12/2019] [Indexed: 12/16/2022]
Abstract
Organic anion transport proteins (OATPs) on the basolateral surface of hepatocytes mediate uptake of a number of drugs and endogenous compounds. Previous studies showed that rat OATP1A1 (rOATP1A1) has a postsynaptic density protein, drosophila disc large tumor suppressor, zonula occludens-1 protein (PDZ) consensus binding motif at its C-terminus and binds to PDZ domain containing 1 (PDZK1), which is required for its cell-surface localization. PDZK1 associates with rOATP1A1-containing endocytic vesicles within cells, mediating recruitment of motor proteins required for microtubule-based trafficking to the plasma membrane. rOATP1A4 also traffics to the plasma membrane, although it lacks a PDZ binding consensus sequence. The current study was designed to test the hypothesis that trafficking of rOATP1A4 to the plasma membrane requires its direct interaction with rOATP1A1 resulting in a complex that traffics through the cell in common subcellular vesicles in which the cytosolic tail of rOATP1A1 is bound to PDZK1. We found that 74% of rOATP1A4-containing rat liver endocytic vesicles (n = 12,044) also contained rOATP1A1. Studies in transfected HEK293 cells showed surface localization of rOATP1A1 only when coexpressed with PDZK1 whereas rOATP1A4 required coexpression with rOATP1A1 and PDZK1. Studies in stably transfected HeLa cells that constitutively expressed PDZK1 showed that coexpression of rOATP1A4 with rOATP1A1 resulted in more rapid appearance of rOATP1A4 on the plasma membrane and faster maturation to its fully glycosylated form. Similar results were observed on immunofluorescence analysis of single cells. Immunoprecipitation of rat liver or transfected HeLa cell lysates with rOATP1A1 antibody specifically co-immunoprecipitated rOATP1A4 as determined by western blotting. Conclusion: These studies indicate that optimal rOATP1A4 trafficking to the cell surface is dependent upon coexpression and interaction with rOATP1A1. As rOATP1A1 binds to the chaperone protein, PDZK1, rOATP1A4 functionally hitchhikes through the cell with this complex.
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Affiliation(s)
- Pijun Wang
- Marion Bessin Liver Research Center, Albert Einstein College of Medicine and Montefiore Medical Center, Bronx, New York 10461, USA
| | - Wen-Jun Wang
- Marion Bessin Liver Research Center, Albert Einstein College of Medicine and Montefiore Medical Center, Bronx, New York 10461, USA,Department of Anatomy and Structural Biology, Albert Einstein College of Medicine and Montefiore Medical Center, Bronx, New York 10461, USA
| | - Jo Choi-Nurvitadhi
- Marion Bessin Liver Research Center, Albert Einstein College of Medicine and Montefiore Medical Center, Bronx, New York 10461, USA,Department of Anatomy and Structural Biology, Albert Einstein College of Medicine and Montefiore Medical Center, Bronx, New York 10461, USA
| | - Yaniuska Lescaille
- Marion Bessin Liver Research Center, Albert Einstein College of Medicine and Montefiore Medical Center, Bronx, New York 10461, USA,Division of Hepatology, Albert Einstein College of Medicine and Montefiore Medical Center, Bronx, New York 10461, USA
| | - John W. Murray
- Marion Bessin Liver Research Center, Albert Einstein College of Medicine and Montefiore Medical Center, Bronx, New York 10461, USA,Department of Anatomy and Structural Biology, Albert Einstein College of Medicine and Montefiore Medical Center, Bronx, New York 10461, USA
| | - Allan W. Wolkoff
- Marion Bessin Liver Research Center, Albert Einstein College of Medicine and Montefiore Medical Center, Bronx, New York 10461, USA,Department of Anatomy and Structural Biology, Albert Einstein College of Medicine and Montefiore Medical Center, Bronx, New York 10461, USA,Division of Hepatology, Albert Einstein College of Medicine and Montefiore Medical Center, Bronx, New York 10461, USA
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11
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Jin H, Wang B, Hou J, Ma T, Qiao D, Miao Y, Ding J, Han X. The mechanism of Oatp1a5-mediated microcystin-leucine arginine entering into GnRH neurons. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2019; 184:109614. [PMID: 31526925 DOI: 10.1016/j.ecoenv.2019.109614] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2019] [Revised: 08/22/2019] [Accepted: 08/26/2019] [Indexed: 06/10/2023]
Abstract
Microcystin-leucine arginine (MC-LR) enters into gonadotropin-releasing hormone (GnRH) neurons and induces decline of serum GnRH levels resulting in male reproductive toxicity via hypothalamic-pituitary-testis axis. The organic anion transporting polypeptide 1a5 (Oatp1a5) is a critical transporter for the uptake of MC-LR by GnRH neurons. However, the underlying molecular mechanisms of the transport process are still elusive. In this study, we found that the transmembrane domains 2, 8, and 9 played important roles in transporting function of Oatp1a5. In addition, our data demonstrated that N-linked glycosylation was involved in the transport of MC-LR by Oatp1a5. Moreover, we showed that N-linked glycosylation sites Asn483 and Asn492 were vital for the transport function of Oatp1a5. In summary, the study furthered our understanding of mechanisms that the uptake of MC-LR by GnRH neurons and laid a theoretical foundation for preventing MC-LR from injuring male reproductive health.
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Affiliation(s)
- Haibo Jin
- Immunology and Reproductive Biology Laboratory & State Key Laboratory of Analytical Chemistry for Life Science, Medical School, Nanjing University, Hankou Road 22, Nanjing, Jiangsu, 210093, China; Jiangsu Key Laboratory of Molecular Medicine, Nanjing University, Nanjing, 210093, China.
| | - Bo Wang
- Immunology and Reproductive Biology Laboratory & State Key Laboratory of Analytical Chemistry for Life Science, Medical School, Nanjing University, Hankou Road 22, Nanjing, Jiangsu, 210093, China; Jiangsu Key Laboratory of Molecular Medicine, Nanjing University, Nanjing, 210093, China.
| | - Jiwei Hou
- Immunology and Reproductive Biology Laboratory & State Key Laboratory of Analytical Chemistry for Life Science, Medical School, Nanjing University, Hankou Road 22, Nanjing, Jiangsu, 210093, China; Jiangsu Key Laboratory of Molecular Medicine, Nanjing University, Nanjing, 210093, China.
| | - Tan Ma
- Immunology and Reproductive Biology Laboratory & State Key Laboratory of Analytical Chemistry for Life Science, Medical School, Nanjing University, Hankou Road 22, Nanjing, Jiangsu, 210093, China; Jiangsu Key Laboratory of Molecular Medicine, Nanjing University, Nanjing, 210093, China.
| | - Dan Qiao
- Immunology and Reproductive Biology Laboratory & State Key Laboratory of Analytical Chemistry for Life Science, Medical School, Nanjing University, Hankou Road 22, Nanjing, Jiangsu, 210093, China; Jiangsu Key Laboratory of Molecular Medicine, Nanjing University, Nanjing, 210093, China.
| | - Yingwen Miao
- Immunology and Reproductive Biology Laboratory & State Key Laboratory of Analytical Chemistry for Life Science, Medical School, Nanjing University, Hankou Road 22, Nanjing, Jiangsu, 210093, China; Jiangsu Key Laboratory of Molecular Medicine, Nanjing University, Nanjing, 210093, China.
| | - Jie Ding
- Immunology and Reproductive Biology Laboratory & State Key Laboratory of Analytical Chemistry for Life Science, Medical School, Nanjing University, Hankou Road 22, Nanjing, Jiangsu, 210093, China; Jiangsu Key Laboratory of Molecular Medicine, Nanjing University, Nanjing, 210093, China.
| | - Xiaodong Han
- Immunology and Reproductive Biology Laboratory & State Key Laboratory of Analytical Chemistry for Life Science, Medical School, Nanjing University, Hankou Road 22, Nanjing, Jiangsu, 210093, China; Jiangsu Key Laboratory of Molecular Medicine, Nanjing University, Nanjing, 210093, China.
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12
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Yue M, Yang J, Jin M, Steiert B, Xiang Y, Zhang H, Hagenbuch B, Gui C. Gly45 and Phe555 in Transmembrane Domains 1 and 10 Are Critical for the Activation of Organic Anion Transporting Polypeptide 1B3 by Epigallocatechin Gallate. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2019; 67:9079-9087. [PMID: 31353905 PMCID: PMC6892160 DOI: 10.1021/acs.jafc.9b03812] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Organic anion transporting polypeptides (OATPs) 1B1 and 1B3 are two highly homologous transporters expressed in the human liver. However, epigallocatechin gallate (EGCG), which is the most predominant catechin in green tea, has opposite effects on the function of OATP1B1 and OATP1B3. In the present study, the critical structural domains and amino acid residues for the activation of OATP1B3 by EGCG have been determined by characterizing the function of a series of OATP1B3-derived chimeric transporters, site-directed mutagenesis, and kinetic studies. Our results showed that G45 and F555 in transmembrane domains 1 and 10 are the most important amino acid residues for OATP1B3 activation. Kinetic studies showed that the activation of OATP1B3 by EGCG at a low substrate concentration was due to its increased substrate binding affinity. However, EGCG caused increased Km and decreased Vmax for 1B3-G45A and 1B3-F555H. The flexibility at position 45 and aromaticity at position 555 might be important for OATP1B3 activation. While 1B3-G45A and 1B3-F555H could not be activated by EGCG, their transport activity for EGCG was comparable to that of wild-type OATP1B3. In conclusion, the present study elucidated the molecular mechanism for OATP1B3 activation by EGCG.
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Affiliation(s)
- Mei Yue
- Department of Pharmaceutical Analysis, College of Pharmaceutical Sciences, Soochow University, Suzhou 215123, China
| | - Jingjie Yang
- Department of Pharmaceutical Analysis, College of Pharmaceutical Sciences, Soochow University, Suzhou 215123, China
| | - Meng Jin
- Department of Pharmaceutical Analysis, College of Pharmaceutical Sciences, Soochow University, Suzhou 215123, China
| | - Brianna Steiert
- Department of Pharmacology, Toxicology and Therapeutics, the University of Kansas Medical Center, Kansas City, Kansas 66160, USA
| | - Yiqun Xiang
- Department of Pharmaceutical Analysis, College of Pharmaceutical Sciences, Soochow University, Suzhou 215123, China
| | - Hongjian Zhang
- Department of Pharmaceutical Analysis, College of Pharmaceutical Sciences, Soochow University, Suzhou 215123, China
| | - Bruno Hagenbuch
- Department of Pharmacology, Toxicology and Therapeutics, the University of Kansas Medical Center, Kansas City, Kansas 66160, USA
| | - Chunshan Gui
- Department of Pharmaceutical Analysis, College of Pharmaceutical Sciences, Soochow University, Suzhou 215123, China
- Corresponding author: Chunshan Gui, Department of Pharmaceutical Analysis, College of Pharmaceutical Sciences, Soochow University, 199 Renai Road, Suzhou Industrial Park, Suzhou 215123, China. Tel.: +86-512-65882089; Fax: +86-512-65882089
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13
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Nie Y, Yang J, Liu S, Sun R, Chen H, Long N, Jiang R, Gui C. Genetic polymorphisms of human hepatic OATPs: functional consequences and effect on drug pharmacokinetics. Xenobiotica 2019; 50:297-317. [DOI: 10.1080/00498254.2019.1629043] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Yingmin Nie
- Department of Pharmaceutical Analysis, College of Pharmaceutical Sciences, Soochow University, Suzhou, China
| | - Jingjie Yang
- Department of Pharmaceutical Analysis, College of Pharmaceutical Sciences, Soochow University, Suzhou, China
| | - Shuai Liu
- Department of Pharmaceutical Analysis, College of Pharmaceutical Sciences, Soochow University, Suzhou, China
| | - Ruiqi Sun
- Department of Pharmaceutical Analysis, College of Pharmaceutical Sciences, Soochow University, Suzhou, China
| | - Huihui Chen
- Department of Pharmaceutical Analysis, College of Pharmaceutical Sciences, Soochow University, Suzhou, China
| | - Nan Long
- Department of Pharmaceutical Analysis, College of Pharmaceutical Sciences, Soochow University, Suzhou, China
| | - Rui Jiang
- Department of Pharmaceutical Analysis, College of Pharmaceutical Sciences, Soochow University, Suzhou, China
| | - Chunshan Gui
- Department of Pharmaceutical Analysis, College of Pharmaceutical Sciences, Soochow University, Suzhou, China
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14
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Murray JW, Yin D, Wolkoff AW. Reduction of organelle motility by removal of potassium and other solutes. PLoS One 2017; 12:e0184898. [PMID: 28922372 PMCID: PMC5602639 DOI: 10.1371/journal.pone.0184898] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Accepted: 09/01/2017] [Indexed: 12/02/2022] Open
Abstract
There are surprisingly few studies that describe how the composition of cell culture medium may affect the trafficking of organelles. Here we utilize time lapse multi-channel fluorescent imaging to show that short term exposure of Huh-7 cells to medium lacking potassium, sodium, or chloride strongly reduces but does not eliminate the characteristic back and forth and cell-traversing movement of fluorescent EGF (FL-EGF) containing organelles. We focused on potassium because of its relatively low abundance in media and serum and its energy requiring accumulation into cells. Upon exposure to potassium free medium, organelle motility declined steadily through 90 min and then persisted at a low level. Reduced motility was confirmed in 5 independent cell lines and for organelles of the endocytic pathway (FL-EGF and Lysotracker), autophagosomes (LC3-GFP), and mitochondria (TMRE). As has been previously established, potassium free medium also inhibited endocytosis. We expected that diminished cellular metabolism would precede loss of organelle motility. However, extracellular flux analysis showed near normal mitochondrial oxygen consumption and only a small decrease in extracellular acidification, the latter suggesting decreased glycolysis or proton efflux. Other energy dependent activities such as the accumulation of Lysotracker, TMRE, DiBAC4(3), and the exclusion of propidium iodide remained intact, as did the microtubule cytoskeleton. We took advantage of cell free in vitro motility assays and found that removal of potassium or sodium from the reconstituted cytosolic medium decreased the movement of endosomes on purified microtubules. The results indicate that although changes in proton homeostasis and cell energetics under solute depletion are not fully understood, potassium as well as sodium appear to be directly required by the motile machinery of organelles for optimal trafficking.
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Affiliation(s)
- John W. Murray
- Marion Bessin Liver Research Center, Division of Gastroenterology and Liver Diseases, Albert Einstein College of Medicine and Montefiore Medical Center, Bronx, New York, United States of America
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine and Montefiore Medical Center, Bronx, New York, United States of America
- * E-mail:
| | - David Yin
- Marion Bessin Liver Research Center, Division of Gastroenterology and Liver Diseases, Albert Einstein College of Medicine and Montefiore Medical Center, Bronx, New York, United States of America
| | - Allan W. Wolkoff
- Marion Bessin Liver Research Center, Division of Gastroenterology and Liver Diseases, Albert Einstein College of Medicine and Montefiore Medical Center, Bronx, New York, United States of America
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine and Montefiore Medical Center, Bronx, New York, United States of America
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15
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Xu D, You G. Loops and layers of post-translational modifications of drug transporters. Adv Drug Deliv Rev 2017; 116:37-44. [PMID: 27174152 DOI: 10.1016/j.addr.2016.05.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Accepted: 05/03/2016] [Indexed: 12/19/2022]
Abstract
Drug transporters encoded by solute carrier (SLC) family are distributed in multiple organs including kidney, liver, placenta, brain, and intestine, where they mediate the absorption, distribution, and excretion of a diverse array of environmental toxins and clinically important drugs. Alterations in the expression and function of these transporters play important roles in intra- and inter-individual variability of the therapeutic efficacy and the toxicity of many drugs. Consequently, the activity of these transporters must be highly regulated to carry out their normal functions. While it is clear that the regulation of these transporters tightly depends on genetic mechanisms, many studies have demonstrated that these transporters are the target of various post-translational modifications. This review article summarizes the recent advances in identifying the posttranslational modifications underlying the regulation of the drug transporters of SLC family. Such mechanisms are pivotal not only in physiological conditions, but also in diseases.
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16
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Abdullahi W, Davis TP, Ronaldson PT. Functional Expression of P-glycoprotein and Organic Anion Transporting Polypeptides at the Blood-Brain Barrier: Understanding Transport Mechanisms for Improved CNS Drug Delivery? AAPS JOURNAL 2017; 19:931-939. [PMID: 28447295 DOI: 10.1208/s12248-017-0081-9] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Accepted: 03/29/2017] [Indexed: 12/28/2022]
Abstract
Drug delivery to the central nervous system (CNS) is greatly limited by the blood-brain barrier (BBB). Physical and biochemical properties of the BBB have rendered treatment of CNS diseases, including those with a hypoxia/reoxygenation (H/R) component, extremely difficult. Targeting endogenous BBB transporters from the ATP-binding cassette (ABC) superfamily (i.e., P-glycoprotein (P-gp)) or from the solute carrier (SLC) family (i.e., organic anion transporting polypeptides (OATPs in humans; Oatps in rodents)) has been suggested as a strategy that can improve delivery of drugs to the brain. With respect to P-gp, direct pharmacological inhibition using small molecules or selective regulation by targeting intracellular signaling pathways has been explored. These approaches have been largely unsuccessful due to toxicity issues and unpredictable pharmacokinetics. Therefore, our laboratory has proposed that optimization of CNS drug delivery, particularly for treatment of diseases with an H/R component, can be achieved by targeting Oatp isoforms at the BBB. As the major drug transporting Oatp isoform, Oatp1a4 has demonstrated blood-to-brain transport of substrate drugs with neuroprotective properties. Furthermore, our laboratory has shown that targeting Oatp1a4 regulation (i.e., TGF-β signaling mediated via the ALK-1 and ALK-5 transmembrane receptors) represents an opportunity to control Oatp1a4 functional expression for the purpose of delivering therapeutics to the CNS. In this review, we will discuss limitations of targeting P-gp-mediated transport activity and the advantages of targeting Oatp-mediated transport. Through this discussion, we will also provide critical information on novel approaches to improve CNS drug delivery by targeting endogenous uptake transporters expressed at the BBB.
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Affiliation(s)
- Wazir Abdullahi
- Department of Pharmacology, College of Medicine, University of Arizona, 1501 N. Campbell Avenue, P.O. Box 245050, Tucson, Arizona, 85724-5050, USA
| | - Thomas P Davis
- Department of Pharmacology, College of Medicine, University of Arizona, 1501 N. Campbell Avenue, P.O. Box 245050, Tucson, Arizona, 85724-5050, USA
| | - Patrick T Ronaldson
- Department of Pharmacology, College of Medicine, University of Arizona, 1501 N. Campbell Avenue, P.O. Box 245050, Tucson, Arizona, 85724-5050, USA.
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17
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Affiliation(s)
- Eleni Kotsampasakou
- University of Vienna; Department of Pharmaceutical Chemistry; Althanstrasse 14 1090 Vienna Austria
| | - Gerhard F. Ecker
- University of Vienna; Department of Pharmaceutical Chemistry; Althanstrasse 14 1090 Vienna Austria
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18
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Bian J, Jin M, Yue M, Wang M, Zhang H, Gui C. Tryptophan Residue Located at the Middle of Putative Transmembrane Domain 11 Is Critical for the Function of Organic Anion Transporting Polypeptide 2B1. Mol Pharm 2016; 13:3553-3563. [DOI: 10.1021/acs.molpharmaceut.6b00648] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Jialin Bian
- Department of Pharmaceutical Analysis, College of Pharmaceutical
Sciences, Soochow University, Suzhou 215123, China
| | - Meng Jin
- Department of Pharmaceutical Analysis, College of Pharmaceutical
Sciences, Soochow University, Suzhou 215123, China
| | - Mei Yue
- Department of Pharmaceutical Analysis, College of Pharmaceutical
Sciences, Soochow University, Suzhou 215123, China
| | - Meiyu Wang
- Department of Pharmaceutical Analysis, College of Pharmaceutical
Sciences, Soochow University, Suzhou 215123, China
| | - Hongjian Zhang
- Department of Pharmaceutical Analysis, College of Pharmaceutical
Sciences, Soochow University, Suzhou 215123, China
| | - Chunshan Gui
- Department of Pharmaceutical Analysis, College of Pharmaceutical
Sciences, Soochow University, Suzhou 215123, China
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19
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Chan T, Lu X, Shams T, Zhu L, Murray M, Zhou F. The Role of N-Glycosylation in Maintaining the Transporter Activity and Expression of Human Oligopeptide Transporter 1. Mol Pharm 2016; 13:3449-3456. [DOI: 10.1021/acs.molpharmaceut.6b00462] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Affiliation(s)
- Ting Chan
- Faculty
of Pharmacy, The University of Sydney, Sydney, NSW 2006, Australia
| | - Xiaoxi Lu
- Faculty
of Pharmacy, The University of Sydney, Sydney, NSW 2006, Australia
| | - Tahiatul Shams
- Faculty
of Pharmacy, The University of Sydney, Sydney, NSW 2006, Australia
| | - Ling Zhu
- Retinal
Therapeutics Research Group, Save Sight Institute, The University of Sydney, Sydney, NSW 2000, Australia
| | - Michael Murray
- Pharmacogenomics
and Drug Development Group, Discipline of Pharmacology, School of
Medical Sciences, The University of Sydney, Sydney, NSW 2006, Australia
| | - Fanfan Zhou
- Faculty
of Pharmacy, The University of Sydney, Sydney, NSW 2006, Australia
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20
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Arita Y, Allen S, Chen G, Zhang W, Wang Y, Owen AJ, Dentinger P, Sidhu SS. Rapid isolation of peptidic inhibitors of the solute carrier family transporters OATP1B1 and OATP1B3 by cell-based phage display selections. Biochem Biophys Res Commun 2016; 473:370-6. [PMID: 26792727 DOI: 10.1016/j.bbrc.2016.01.050] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Accepted: 01/08/2016] [Indexed: 11/30/2022]
Abstract
OATP1B1 and OATP1B3 (1B3) are members of organic anion-transporting polypeptides (OATPs), a family of sodium-independent organic anion membrane transporters that contribute to transport of various drugs. To identify peptide inhibitors of OATP1B1, we developed a direct selection system on live cells using phage-displayed peptide libraries. Selections against OATP1B1 overexpressed cell-lines yielded three unique peptides able to inhibit the transport function of OATP1B1 and 1B3. Affinity maturation of one peptide led to identification of two peptides that demonstrated improved inhibition efficacy on drug uptake mediated by OATP1B1 and 1B3. We anticipate that these peptides will assist the identification of novel substrates for OATP1B1 and 1B3. Moreover, our selection system is a practical method for generating inhibitors of other membrane transporters.
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Affiliation(s)
- Yuko Arita
- Banting and Best Department of Medical Research and Department of Molecular Genetics, The Donnelly Centre, University of Toronto, Toronto, ON Canada
| | | | - Gang Chen
- Banting and Best Department of Medical Research and Department of Molecular Genetics, The Donnelly Centre, University of Toronto, Toronto, ON Canada
| | - Wei Zhang
- Absorption Systems LP, Exton, PA, USA
| | - Ying Wang
- Absorption Systems LP, Exton, PA, USA
| | | | | | - Sachdev S Sidhu
- Banting and Best Department of Medical Research and Department of Molecular Genetics, The Donnelly Centre, University of Toronto, Toronto, ON Canada.
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21
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Patik I, Kovacsics D, Német O, Gera M, Várady G, Stieger B, Hagenbuch B, Szakács G, Özvegy-Laczka C. Functional expression of the 11 human Organic Anion Transporting Polypeptides in insect cells reveals that sodium fluorescein is a general OATP substrate. Biochem Pharmacol 2015; 98:649-58. [PMID: 26415544 DOI: 10.1016/j.bcp.2015.09.015] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Accepted: 09/17/2015] [Indexed: 11/29/2022]
Abstract
Organic Anion Transporting Polypeptides (OATPs), encoded by genes of the Solute Carrier Organic Anion (SLCO) family, are transmembrane proteins involved in the uptake of various compounds of endogenous or exogenous origin. In addition to their physiological roles, OATPs influence the pharmacokinetics and drug-drug interactions of several clinically relevant compounds. To examine the function and molecular interactions of human OATPs, including several poorly characterized family members, we expressed all 11 human OATPs at high levels in the baculovirus-Sf9 cell system. We measured the temperature- and inhibitor-sensitive cellular accumulation of sodium fluorescein and fluorescein-methotrexate, two fluorescent substrates of the OATPs, OATP1B1 and 1B3. OATP1B1 and 1B3 were functional in Sf9 cells, showing rapid uptake (t1/2(fluorescein-methotrexate) 2.64 and 4.16 min, and t1/2(fluorescein) 6.71 and 5.58 min for OATP1B1 and 1B3, respectively) and high-affinity transport (Km(fluorescein-methotrexate) 0.23 and 0.53 μM, and Km(fluorescein) 25.73 and 38.55 μM for OATP1B1 and 1B3, respectively) of both substrates. We found that sodium fluorescein is a general substrate of all human OATPs: 1A2, 1B1, 1B3, 1C1, 2A1, 2B1, 3A1, 4A1, 4C1, 5A1 and 6A1, while fluorescein-methotrexate is only transported by 1B1, 1B3, 1A2 and 2B1. Acidic extracellular pH greatly facilitated fluorescein uptake by all OATPs, and new molecular interactions were detected (between OATP2B1 and Imatinib, OATP3A1, 5A1 and 6A1 and estradiol 17-β-d-glucuronide, and OATP1C1 and 4C1 and prostaglandin E2). These studies demonstrate, for the first time, that the insect cell system is suitable for the functional analysis of the entire human OATP family, and for drug-OATP interaction screening.
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Affiliation(s)
- Izabel Patik
- Momentum Membrane Protein Research Group, Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar tudósok krt. 2, H-1117 Budapest, Hungary
| | - Daniella Kovacsics
- Momentum Membrane Protein Research Group, Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar tudósok krt. 2, H-1117 Budapest, Hungary
| | - Orsolya Német
- Momentum Membrane Protein Research Group, Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar tudósok krt. 2, H-1117 Budapest, Hungary
| | - Melinda Gera
- Momentum Membrane Protein Research Group, Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar tudósok krt. 2, H-1117 Budapest, Hungary
| | - György Várady
- Laboratory of Molecular Cell Biology, Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar tudósok krt. 2, H-1117 Budapest, Hungary
| | - Bruno Stieger
- Department of Clinical Pharmacology and Toxicology, University Hospital, 8091 Zurich, Switzerland
| | - Bruno Hagenbuch
- Department of Pharmacology, Toxicology and Therapeutics, The University of Kansas Medical Center, Kansas City, KA 66160, USA
| | - Gergely Szakács
- Momentum Membrane Protein Research Group, Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar tudósok krt. 2, H-1117 Budapest, Hungary
| | - Csilla Özvegy-Laczka
- Momentum Membrane Protein Research Group, Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar tudósok krt. 2, H-1117 Budapest, Hungary.
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22
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Abstract
Many of the compounds taken up by the liver are organic anions that circulate tightly bound to protein carriers such as albumin. The fenestrated sinusoidal endothelium of the liver permits these compounds to have access to hepatocytes. Studies to characterize hepatic uptake of organic anions through kinetic analyses, suggested that it was carrier-mediated. Attempts to identify specific transporters by biochemical approaches were largely unsuccessful and were replaced by studies that utilized expression cloning. These studies led to identification of the organic anion transport proteins (oatps), a family of 12 transmembrane domain glycoproteins that have broad and often overlapping substrate specificities. The oatps mediate Na(+)-independent organic anion uptake. Other studies identified a seven transmembrane domain glycoprotein, Na(+)/taurocholate transporting protein (ntcp) as mediating Na(+)-dependent uptake of bile acids as well as other organic anions. Although mutations or deficiencies of specific members of the oatp family have been associated with transport abnormalities, there have been no such reports for ntcp, and its physiologic role remains to be determined, although expression of ntcp in vitro recapitulates the characteristics of Na(+)-dependent bile acid transport that is seen in vivo. Both ntcp and oatps traffic between the cell surface and intracellular vesicular pools. These vesicles move through the cell on microtubules, using the microtubule based motors dynein and kinesins. Factors that regulate this motility are under study and may provide a unique mechanism that can alter the plasma membrane content of these transporters and consequently their accessibility to circulating ligands.
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Affiliation(s)
- Allan W Wolkoff
- The Herman Lopata Chair in Liver Disease Research, Professor of Medicine and Anatomy and Structural Biology, Associate Chair of Medicine for Research, Chief, Division of Gastroenterology and Liver Diseases, Director, Marion Bessin Liver Research Center, Albert Einstein College of Medicine and Montefiore Medical Center, Bronx, NY
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23
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Steiner K, Zimmermann L, Hagenbuch B, Dietrich D. Zebrafish Oatp-mediated transport of microcystin congeners. Arch Toxicol 2015; 90:1129-39. [PMID: 26055554 DOI: 10.1007/s00204-015-1544-3] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Accepted: 05/28/2015] [Indexed: 01/07/2023]
Abstract
Microcystins (MC), representing >100 congeners being produced by cyanobacteria, are a hazard for aquatic species. As MC congeners vary in their toxicity, the congener composition of a bloom primarily dictates the severity of adverse effects and appears primarily to be governed by toxicokinetics, i.e., whether transport of MCs occurs via organic anion-transporting polypeptides (Oatps). Differences in observed MC toxicity in various fish species suggest differential expression of Oatp subtypes leading to varying tissue distribution of the very same MC congener within different species. The objectives of this study were the functional characterization and analysis of the tissue distribution of Oatp subtypes in zebrafish (Danio rerio) as a surrogate model for cyprinid fish. Zebrafish Oatps (zfOatps) were cloned, and the organ distribution was determined at the mRNA level. zfOatps were transiently expressed in HEK293 cells for functional characterization using the Oatp substrates estrone-3-sulfate, taurocholate and methotrexate and specific MC congeners (MC-LR, MC-RR, MC-LF and MC-LW). Novel zfOatp isoforms were isolated. Among these isoforms, the organ-specific expression of zfOatp1d1 and of members of the zfOatp1f subfamily was identified. At the functional level, zfOatp1d1, zfOatp1f2, zfOatp1f3 and zfOatp1f4 transported at least one of the Oatp substrates, and zfOatp1d1, zfOatp1f2 and zfOatp1f4 were shown to transport MC congeners. MC-LF and MC-LW were generally transported faster than MC-LR and MC-RR. The subtype-specific expression of zfOatp1d1 and of members of the zfOatp1f subfamily as well as differences in the transport of MC congeners could explain the MC congener-dependent differences in toxicity in cyprinids.
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Affiliation(s)
- Konstanze Steiner
- Human and Environmental Toxicology, Department of Biology, University of Konstanz, PO BOX 662, 78457, Constance, Germany
| | - Lisa Zimmermann
- Human and Environmental Toxicology, Department of Biology, University of Konstanz, PO BOX 662, 78457, Constance, Germany
| | - Bruno Hagenbuch
- Pharmacology, Toxicology and Therapeutics, The University of Kansas Medical Center, Kansas City, KS, USA
| | - Daniel Dietrich
- Human and Environmental Toxicology, Department of Biology, University of Konstanz, PO BOX 662, 78457, Constance, Germany.
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24
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Abstract
Organic anion-transporting polypeptides or OATPs are central transporters in the disposition of drugs and other xenobiotics. In addition, they mediate transport of a wide variety of endogenous substrates. The critical role of OATPs in drug disposition has spurred research both in academia and in the pharmaceutical industry. Translational aspects with clinical questions are the focus in academia, while the pharmaceutical industry tries to define and understand the role these transporters play in pharmacotherapy. The present overview summarizes our knowledge on the interaction of food constituents with OATPs and on the OATP transport mechanisms. Further, it gives an update on the available information on the structure-function relationship of the OATPs and, finally, covers the transcriptional and posttranscriptional regulation of OATPs.
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Affiliation(s)
- Bruno Stieger
- Department of Clinical Pharmacology and Toxicology, University Hospital, Zürich, Switzerland.
| | - Bruno Hagenbuch
- Department of Pharmacology, Toxicology and Therapeutics, The University of Kansas Medical Center, Kansas City, Kansas, USA
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The Signature Sequence Region of the Human Drug Transporter Organic Anion Transporting Polypeptide 1B1 Is Important for Protein Surface Expression. JOURNAL OF DRUG DELIVERY 2014; 2014:129849. [PMID: 25371825 PMCID: PMC4209838 DOI: 10.1155/2014/129849] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Revised: 09/10/2014] [Accepted: 09/15/2014] [Indexed: 12/26/2022]
Abstract
The organic anion transporting polypeptides (OATPs) encompass a family of membrane transport proteins responsible for the uptake of xenobiotic compounds. Human organic anion transporting polypeptide 1B1 (OATP1B1) mediates the uptake of clinically relevant compounds such as statins and chemotherapeutic agents into hepatocytes, playing an important role in drug delivery and detoxification.
The OATPs have a putative 12-transmembrane domain topology and a highly conserved signature sequence (human OATP1B1: DSRWVGAWWLNFL), spanning the extracellular loop 3/TM6 boundary. The presence of three conserved tryptophan residues at the TM interface suggests a structural role for the sequence. This was investigated by site-directed mutagenesis of selected amino acids within the sequence D251E, W254F, W258/259F, and N261A. Transport was measured using the substrate estrone-3-sulfate and surface expression detected by luminometry and confocal microscopy, facilitated by an extracellular FLAG epitope. Uptake of estrone-3-sulfate and the surface expression of D251E, W254F, and W258/259F were both significantly reduced from the wild type OATP1B1-FLAG in transfected HEK293T cells. Confocal microscopy revealed that protein was produced but was retained intracellularly. The uptake and expression of N261A were not significantly different. The reduction in surface expression and intracellular protein retention indicates a structural and/or membrane localization role for these signature sequence residues in the human drug transporter OATP1B1.
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Popovic M, Zaja R, Fent K, Smital T. Molecular characterization of zebrafish Oatp1d1 (Slco1d1), a novel organic anion-transporting polypeptide. J Biol Chem 2013; 288:33894-33911. [PMID: 24126916 DOI: 10.1074/jbc.m113.518506] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The organic anion-transporting polypeptide (OATP/Oatp) superfamily includes a group of polyspecific transporters that mediate transport of large amphipathic, mostly anionic molecules across cell membranes of eukaryotes. OATPs/Oatps are involved in the disposition and elimination of numerous physiological and foreign compounds. However, in non-mammalian species, the functional properties of Oatps remain unknown. We aimed to elucidate the role of Oatp1d1 in zebrafish to gain insights into the functional and structural evolution of the OATP1/Oatp1 superfamily. We show that diversification of the OATP1/Oatp1 family occurs after the emergence of jawed fish and that the OATP1A/Oatp1a and OATP1B/Oatp1b subfamilies appeared at the root of tetrapods. The Oatp1d subfamily emerged in teleosts and is absent in tetrapods. The zebrafish Oatp1d1 is similar to mammalian OATP1A/Oatp1a and OATP1B/Oatp1b members, with the main physiological role in transport and balance of steroid hormones. Oatp1d1 activity is dependent upon pH gradient, which could indicate bicarbonate exchange as a mode of transport. Our analysis of evolutionary conservation and structural properties revealed that (i) His-79 in intracellular loop 3 is conserved within OATP1/Oatp1 family and is crucial for the transport activity; (ii) N-glycosylation impacts membrane targeting and is conserved within the OATP1/Oatp1 family with Asn-122, Asn-133, Asn-499, and Asn-512 residues involved; (iii) the evolutionarily conserved cholesterol recognition interaction amino acid consensus motif is important for membrane localization; and (iv) Oatp1d1 is present in dimeric and possibly oligomeric form in the cell membrane. In conclusion, we describe the first detailed characterization of a new Oatp transporter in zebrafish, offering important insights into the functional evolution of the OATP1/Oatp1 family and the physiological role of Oatp1d1.
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Affiliation(s)
- Marta Popovic
- Laboratory for Molecular Ecotoxicology, Division for Marine and Environmental Research, Rudjer Boskovic Institute, Bijenicka 54, 10 000 Zagreb, Croatia
| | - Roko Zaja
- Laboratory for Molecular Ecotoxicology, Division for Marine and Environmental Research, Rudjer Boskovic Institute, Bijenicka 54, 10 000 Zagreb, Croatia
| | - Karl Fent
- School of Life Sciences, University of Applied Sciences Northwestern Switzerland, Gründenstrasse 40, CH-4132 Muttenz, Switzerland; Department of Environmental System Sciences, Swiss Federal Institute of Technology (ETHZ), CH-8092 Zürich, Switzerland
| | - Tvrtko Smital
- Laboratory for Molecular Ecotoxicology, Division for Marine and Environmental Research, Rudjer Boskovic Institute, Bijenicka 54, 10 000 Zagreb, Croatia.
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Wang WJ, Murray JW, Wolkoff AW. Oatp1a1 requires PDZK1 to traffic to the plasma membrane by selective recruitment of microtubule-based motor proteins. Drug Metab Dispos 2013; 42:62-9. [PMID: 24115750 DOI: 10.1124/dmd.113.054536] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Previous studies identified a family of organic anion transport proteins (OATPs), many of which have C-terminal PDZ binding consensus sequences. In particular, the C-terminal four amino acids of Oatp1a1, a transporter on rat and mouse hepatocytes, comprise a consensus binding site for PDZK1. In PDZK1 knockout mice and in transfected cells where PDZK1 expression was knocked down, Oatp1a1 accumulates in intracellular vesicles. The present study tests the hypothesis that Oatp1a1 traffics to and from the cell surface in vesicles along microtubules, and that PDZK1 guides recruitment of specific motors to these vesicles. Oatp1a1-containing vesicles were prepared from wild-type and PDZK1 knockout mice. As seen by immunofluorescence, kinesin-1, a microtubule plus-end directed motor, was largely associated with vesicles from wild-type mouse liver, whereas dynein, a minus-end directed motor, was largely associated with vesicles from PDZK1 knockout mouse liver. Quantification of motility on directionally marked microtubules following addition of 50 µM ATP showed that wild-type vesicles moved equally toward the plus and minus ends whereas PDZK1 knockout vesicles moved predominantly toward the minus end, consistent with net movement toward the cell interior. These studies provide a novel mechanism by which PDZK1 regulates intracellular trafficking of Oatp1a1 by recruiting specific motors to Oatp1a1-containing vesicles. In the absence of PDZK1, Oatp1a1-containing vesicles cannot recruit kinesin-1 and associate with dynein as a predominant minus-end directed motor. Whether this is a result of direct interaction of the Oatp1a1 cytoplasmic domain with dynein or with a dynein-containing protein complex remains to be established.
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Affiliation(s)
- Wen-Jun Wang
- Department of Anatomy and Structural Biology, Marion Bessin Liver Research Center, Division of Gastroenterology and Liver Diseases, Albert Einstein College of Medicine, Bronx, New York
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Hagenbuch B, Stieger B. The SLCO (former SLC21) superfamily of transporters. Mol Aspects Med 2013; 34:396-412. [PMID: 23506880 DOI: 10.1016/j.mam.2012.10.009] [Citation(s) in RCA: 260] [Impact Index Per Article: 23.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2012] [Accepted: 09/19/2012] [Indexed: 01/04/2023]
Abstract
The members of the organic anion transporting polypeptide superfamily (OATPs) are classified within the SLCO solute carrier family. All functionally well characterized members are predicted to have 12 transmembrane domains and are sodium-independent transport systems that mediate the transport of a broad range of endo- as well as xenobiotics. Substrates are mainly amphipathic organic anions with a molecular weight of more than 300Da, but some of the known transported substrates are also neutral or even positively charged. Among the well characterized substrates are numerous drugs including statins, angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, antibiotics, antihistaminics, antihypertensives and anticancer drugs. Based on their amino acid sequence identities, the different OATPs cluster into families (in general with more than 40% amino acid sequence identity) and subfamilies (more than 60% amino acid identity). With the sequencing of genomes from different species and the computerized prediction of encoded proteins more than 300 OATPs can be found in the databases, however only a fraction of them have been identified in humans, rodents, and some additional species important for pharmaceutical research like the rhesus monkey (Macaca mulatta), the dog (Canis lupus familiaris) and the pig (Sus scrofa). These OATPs form 6 families (OATP1-OATP6) and 13 subfamilies. In this review we try to summarize what is currently known about OATPs with respect to endogenous substrates, tissue distribution, transport mechanisms, regulation of expression, structure-function relationship and mutations and polymorphisms.
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Affiliation(s)
- Bruno Hagenbuch
- Department of Pharmacology, Toxicology and Therapeutics, The University of Kansas Medical Center, Kansas City, KS 66160, USA.
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Ronaldson PT, Davis TP. Targeted drug delivery to treat pain and cerebral hypoxia. Pharmacol Rev 2013; 65:291-314. [PMID: 23343976 DOI: 10.1124/pr.112.005991] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Limited drug penetration is an obstacle that is often encountered in treatment of central nervous system (CNS) diseases including pain and cerebral hypoxia. Over the past several years, biochemical characteristics of the brain (i.e., tight junction protein complexes at brain barrier sites, expression of influx and efflux transporters) have been shown to be directly involved in determining CNS permeation of therapeutic agents; however, the vast majority of these studies have focused on understanding those mechanisms that prevent drugs from entering the CNS. Recently, this paradigm has shifted toward identifying and characterizing brain targets that facilitate CNS drug delivery. Such targets include the organic anion-transporting polypeptides (OATPs in humans; Oatps in rodents), a family of sodium-independent transporters that are endogenously expressed in the brain and are involved in drug uptake. OATP/Oatp substrates include drugs that are efficacious in treatment of pain and/or cerebral hypoxia (i.e., opioid analgesic peptides, 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors). This clearly suggests that OATP/Oatp isoforms are viable transporter targets that can be exploited for optimization of drug delivery to the brain and, therefore, improved treatment of CNS diseases. This review summarizes recent knowledge in this area and emphasizes the potential that therapeutic targeting of OATP/Oatp isoforms may have in facilitating CNS drug delivery and distribution. Additionally, information presented in this review will point to novel strategies that can be used for treatment of pain and cerebral hypoxia.
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Affiliation(s)
- Patrick T Ronaldson
- Department of Medical Pharmacology, College of Medicine, University of Arizona, 1501 North Campbell Avenue, P.O. Box 245050, Tucson, AZ 85724-5050, USA.
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N-Glycosylation dictates proper processing of organic anion transporting polypeptide 1B1. PLoS One 2012; 7:e52563. [PMID: 23285087 PMCID: PMC3527552 DOI: 10.1371/journal.pone.0052563] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2012] [Accepted: 11/16/2012] [Indexed: 11/19/2022] Open
Abstract
Organic anion transporting polypeptides (OATPs) have been extensively recognized as key determinants of absorption, distribution, metabolism and excretion (ADME) of various drugs, xenobiotics and toxins. Putative N-glycosylation sites located in the extracellular loops 2 and 5 is considered a common feature of all OATPs and some members have been demonstrated to be glycosylated proteins. However, experimental evidence is still lacking on how such a post-translational modification affect the transport activity of OATPs and which of the putative glycosylation sites are utilized in these transporter proteins. In the present study, we substituted asparagine residues that are possibly involved in N-glycosylation with glutamine residues and identified three glycosylation sites (Asn134, Asn503 and Asn516) within the structure of OATP1B1, an OATP member that is mainly expressed in the human liver. Our results showed that Asn134 and Asn516 are used for glycosylation under normal conditions; however, when Asn134 was mutagenized, an additional asparagine at position 503 is involved in the glycosylation process. Simultaneously replacement of all three asparagines with glutamines led to significantly reduced protein level as well as loss of transport activity. Further studies revealed that glycosylation affected stability of the transporter protein and the unglycosylated mutant was retained within endoplasmic reticulum.
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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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32
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DeGorter MK, Ho RH, Leake BF, Tirona RG, Kim RB. Interaction of three regiospecific amino acid residues is required for OATP1B1 gain of OATP1B3 substrate specificity. Mol Pharm 2012; 9:986-95. [PMID: 22352740 DOI: 10.1021/mp200629s] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The human organic anion-transporting polypeptides OATP1B1 (SLCO1B1) and OATP1B3 (SLCO1B3) are liver-enriched membrane transporters of major importance to hepatic uptake of numerous endogenous compounds, including bile acids, steroid conjugates, hormones, and drugs, including the 3-hydroxy-3-methylglutaryl Co-A reductase inhibitor (statin) family of cholesterol-lowering compounds. Despite their remarkable substrate overlap, there are notable exceptions: in particular, the gastrointestinal peptide hormone cholecystokinin-8 (CCK-8) is a high affinity substrate for OATP1B3 but not OATP1B1. We utilized homologous recombination of linear DNA by E. coli to generate a library of cDNA containing monomer size chimeric OATP1B1-1B3 and OATP1B3-1B1 transporters with randomly distributed chimeric junctions to identify three discrete regions of the transporter involved in conferring CCK-8 transport activity. Site-directed mutagenesis of three key residues in OATP1B1 transmembrane helices 1 and 10, and extracellular loop 6, to the corresponding residues in OATP1B3, resulted in a gain of CCK-8 transport by OATP1B1. The residues appear specific to CCK-8, as the mutations did not affect transport of the shared OATP1B substrate atorvastatin or the OATP1B1-specific substrate estrone sulfate. Regions involved in gain of CCK-8 transport by OATP1B1, when mapped to the crystal structures of bacterial transporters from the major facilitator superfamily, are positioned to suggest these regions could readily interact with drug substrates. Accordingly, our data provide new insight into the molecular determinants of the substrate specificity of these hepatic uptake transporters with relevance to targeted drug design and prediction of drug-drug interactions.
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Affiliation(s)
- Marianne K DeGorter
- Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada
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Murray JW, Thosani AJ, Wang P, Wolkoff AW. Heterogeneous accumulation of fluorescent bile acids in primary rat hepatocytes does not correlate with their homogenous expression of ntcp. Am J Physiol Gastrointest Liver Physiol 2011; 301:G60-8. [PMID: 21474652 PMCID: PMC3129936 DOI: 10.1152/ajpgi.00035.2011] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Sodium taurocholate-cotransporting polypeptide (ntcp) is considered to be a major determinant of bile acid uptake into hepatocytes. However, the regulation of ntcp and the degree that it participates in the accumulation of specific substrates are not well understood. We utilized fluorescent bile acid derivatives and direct quantitation of fluorescent microscopy images to examine the regulation of ntcp and its role in the cell-to-cell variability of fluorescent bile acid accumulation. Primary-cultured rat hepatocytes rapidly accumulated the fluorescent bile acids, chenodeoxycholylglycylamidofluorescein (CDCGamF), 7-β- nitrobenzoxadiazole 3-α hydroxy 5-β cholan-24-oic acid (NBD-CA), and cholyl-glycylamido-fluorescein (CGamF). However, in stably transfected HeLa cells, ntcp preferred CDCGamF, whereas the organic anion transporter, organic anion transporting polypeptide 1 (oatp1a1), preferred NBD-CA, and neither ntcp nor oatp1a1 showed strong accumulation of CGamF by these methods. Ntcp-mediated transport of CDCGamF was inhibited by taurocholate, cyclosporin, actin depolymerization, and an inhibitor of atypical PKC-ζ. The latter two agents altered the cellular distribution of ntcp as visualized in ntcp-green fluorescent protein-transfected cells. Although fluorescent bile acid accumulation was reproducible by the imaging assays, individual cells showed variable accumulation that was not attributable to changes in membrane permeability or cell viability. In HeLa cells, this was accounted for by variable levels of ntcp, whereas, in hepatocytes, ntcp expression was uniform, and low accumulation was seen in a large portion of cells despite the presence of ntcp. These studies indicate that single-cell imaging can provide insight into previously unrecognized details of anion transport in the complex environment of polarized hepatocytes.
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Affiliation(s)
- John W. Murray
- 1Department of Anatomy and Structural Biology, ,2Marion Bessin Liver Research Center and Division of Gastroenterology and Liver Diseases, Albert Einstein College of Medicine, Bronx, New York
| | - Amar J. Thosani
- 2Marion Bessin Liver Research Center and Division of Gastroenterology and Liver Diseases, Albert Einstein College of Medicine, Bronx, New York
| | - Pijun Wang
- 1Department of Anatomy and Structural Biology, ,2Marion Bessin Liver Research Center and Division of Gastroenterology and Liver Diseases, Albert Einstein College of Medicine, Bronx, New York
| | - Allan W. Wolkoff
- 1Department of Anatomy and Structural Biology, ,2Marion Bessin Liver Research Center and Division of Gastroenterology and Liver Diseases, Albert Einstein College of Medicine, Bronx, New York
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Choi JH, Murray JW, Wolkoff AW. PDZK1 binding and serine phosphorylation regulate subcellular trafficking of organic anion transport protein 1a1. Am J Physiol Gastrointest Liver Physiol 2011; 300:G384-93. [PMID: 21183661 PMCID: PMC3064118 DOI: 10.1152/ajpgi.00500.2010] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Although perturbation of organic anion transport protein (oatp) cell surface expression can result in drug toxicity, little is known regarding mechanisms regulating its subcellular distribution. Many members of the oatp family, including oatp1a1, have a COOH-terminal PDZ consensus binding motif that interacts with PDZK1, while serines upstream of this site (S634 and S635) can be phosphorylated. Using oatp1a1 as a prototypical member of the oatp family, we prepared plasmids in which these serines were mutated to glutamic acid [E634E635 (oatp1a1(EE)), phosphomimetic] or alanine [A634A635 (oatp1a1(AA)), nonphosphorylatable]. Distribution of oatp1a1(AA) and oatp1a1(EE) was largely intracellular in transfected human embryonic kidney (HEK) 293T cells. Cotransfection with a plasmid encoding PDZK1 revealed that oatp1a1(AA) was now expressed largely on the cell surface, while oatp1a1(EE) remained intracellular. To quantify these changes, studies were performed in HuH7 cells stably transfected with these oatp1a1 plasmids. These cells endogenously express PDZK1. Surface biotinylation at 4°C followed by shift to 37°C showed that oatp1a1(EE) internalizes quickly compared with oatp1a1(AA). To examine a physiological role for phosphorylation in oatp1a1 subcellular distribution, studies were performed in rat hepatocytes exposed to extracellular ATP, a condition that stimulates serine phosphorylation of oatp1a1 via activity of a purinergic receptor. Internalization of oatp1a1 under these conditions was rapid. Thus, although PDZK1 binding is required for optimal cell surface expression of oatp1a1, phosphorylation provides a mechanism for fast regulation of the distribution of oatp1a1 between the cell surface and intracellular vesicular pools. Identification of the proteins and motor molecules that mediate these trafficking events represents an important area for future study.
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Affiliation(s)
- Jo H. Choi
- 1Marion Bessin Liver Research Center, ,3Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, New York
| | - John W. Murray
- 1Marion Bessin Liver Research Center, ,3Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, New York
| | - Allan W. Wolkoff
- 1Marion Bessin Liver Research Center, ,2Division of Gastroenterology and Liver Diseases, and ,3Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, New York
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Weaver YM, Hagenbuch B. Several conserved positively charged amino acids in OATP1B1 are involved in binding or translocation of different substrates. J Membr Biol 2010; 236:279-90. [PMID: 20821001 DOI: 10.1007/s00232-010-9300-3] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2010] [Accepted: 08/16/2010] [Indexed: 12/20/2022]
Abstract
OATP1B1 and 1B3 are related transporters mediating uptake of numerous compounds into hepatocytes. A putative model of OATP1B3 with a "positive binding pocket" containing conserved positively charged amino acids was predicted (Meier-Abt et al. J Membr Biol 208:213-227, 2005). Based on this model, we tested the hypothesis that these positive amino acids are important for OATP1B1 function. We made mutants and measured surface expression and uptake of estradiol-17β-glucuronide, estrone-3-sulfate and bromosulfophthalein in HEK293 cells. Two of the mutants had low surface expression levels: R181K at 10% and R580A at 30% of wild-type OATP1B1. A lysine at position 580 (R580K) rescued the expression of R580A. Mutations of several amino acids resulted in substrate-dependent effects. The largest changes were seen for estradiol-17β-glucuronide, while estrone-3-sulfate and bromosulfophthalein transport were less affected. The wild-type OATP1B1 K (m) value for estradiol-17β-glucuronide of 5.35 ± 0.54 μM was increased by R57A to 30.5 ± 3.64 μM and decreased by R580K to 0.52 ± 0.18 μM. For estrone-3-sulfate the wild-type high-affinity K (m) value of 0.55 ± 0.12 μM was increased by K361R to 1.8 ± 0.47 μM and decreased by R580K to 0.1 ± 0.04 μM. In addition, R580K reduced the V (max) values for all three substrates to <25% of wild-type OATP1B1. Mutations at intracellular K90, H92 and R93 mainly affected V (max) values for estradiol-17β-glucuronide uptake. In conclusion, the conserved amino acids R57, K361 and R580 seem to be part of the substrate binding sites and/or translocation pathways in OATP1B1.
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Affiliation(s)
- Yi M Weaver
- Department of Pharmacology, Toxicology and Therapeutics, The University of Kansas Medical Center, Kansas City, KS 66160, USA
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36
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Klaassen CD, Aleksunes LM. Xenobiotic, bile acid, and cholesterol transporters: function and regulation. Pharmacol Rev 2010; 62:1-96. [PMID: 20103563 PMCID: PMC2835398 DOI: 10.1124/pr.109.002014] [Citation(s) in RCA: 563] [Impact Index Per Article: 40.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Transporters influence the disposition of chemicals within the body by participating in absorption, distribution, and elimination. Transporters of the solute carrier family (SLC) comprise a variety of proteins, including organic cation transporters (OCT) 1 to 3, organic cation/carnitine transporters (OCTN) 1 to 3, organic anion transporters (OAT) 1 to 7, various organic anion transporting polypeptide isoforms, sodium taurocholate cotransporting polypeptide, apical sodium-dependent bile acid transporter, peptide transporters (PEPT) 1 and 2, concentrative nucleoside transporters (CNT) 1 to 3, equilibrative nucleoside transporter (ENT) 1 to 3, and multidrug and toxin extrusion transporters (MATE) 1 and 2, which mediate the uptake (except MATEs) of organic anions and cations as well as peptides and nucleosides. Efflux transporters of the ATP-binding cassette superfamily, such as ATP-binding cassette transporter A1 (ABCA1), multidrug resistance proteins (MDR) 1 and 2, bile salt export pump, multidrug resistance-associated proteins (MRP) 1 to 9, breast cancer resistance protein, and ATP-binding cassette subfamily G members 5 and 8, are responsible for the unidirectional export of endogenous and exogenous substances. Other efflux transporters [ATPase copper-transporting beta polypeptide (ATP7B) and ATPase class I type 8B member 1 (ATP8B1) as well as organic solute transporters (OST) alpha and beta] also play major roles in the transport of some endogenous chemicals across biological membranes. This review article provides a comprehensive overview of these transporters (both rodent and human) with regard to tissue distribution, subcellular localization, and substrate preferences. Because uptake and efflux transporters are expressed in multiple cell types, the roles of transporters in a variety of tissues, including the liver, kidneys, intestine, brain, heart, placenta, mammary glands, immune cells, and testes are discussed. Attention is also placed upon a variety of regulatory factors that influence transporter expression and function, including transcriptional activation and post-translational modifications as well as subcellular trafficking. Sex differences, ontogeny, and pharmacological and toxicological regulation of transporters are also addressed. Transporters are important transmembrane proteins that mediate the cellular entry and exit of a wide range of substrates throughout the body and thereby play important roles in human physiology, pharmacology, pathology, and toxicology.
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Affiliation(s)
- Curtis D Klaassen
- Department of Pharmacology, Toxicology, and Therapeutics, University of Kansas Medical Center, 3901 Rainbow Blvd., Kansas City, KS 66160-7417, USA.
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37
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Gui C, Hagenbuch B. Role of transmembrane domain 10 for the function of organic anion transporting polypeptide 1B1. Protein Sci 2010; 18:2298-306. [PMID: 19760661 DOI: 10.1002/pro.240] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The liver-specific organic anion transporting polypeptides OATP1B1 and OATP1B3 are highly homologous and share numerous substrates. However, at low concentrations OATP1B1 shows substrate selectivity for estrone-3-sulfate. In this study, we investigated the molecular mechanism for this substrate selectivity of OATP1B1 by constructing OATP1B1/1B3 chimeric transporters and by site-directed mutagenesis. Functional studies of chimeras showed that transmembrane domain 10 is critical for the function of OATP1B1. We further identified four amino acid residues, namely L545, F546, L550, and S554 in TM10, whose simultaneous mutation caused almost complete loss of OATP1B1-mediated estrone-3-sulfate transport. Comparison of the kinetics of estrone-3-sulfate transport confirmed a biphasic pattern for OATP1B1, but showed a monophasic pattern for the quadruple mutant L545S/F546L/L550T/S554T. This mutant also showed reduced transport for other OATP1B1 substrates such as bromosulfophthalein and [D-penicillamine(2,5)]enkephalin. Helical wheel analysis and molecular modeling suggest that L545 is facing the substrate translocation pathway, whereas F546, L550, and S554 are located inside the protein. These results indicate that L545 might contribute to OATP1B1 function by interacting with substrates, whereas F546, L550, and S554 seem important for protein structure. In conclusion, our results show that TM10 is critical for the function of OATP1B1.
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Affiliation(s)
- Chunshan Gui
- Department of Pharmacology, Toxicology and Therapeutics, University of Kansas Medical Center, Kansas City, Kansas 66160, USA
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Organic anion transporting polypeptide (Oatp) 1a1-mediated perfluorooctanoate transport and evidence for a renal reabsorption mechanism of Oatp1a1 in renal elimination of perfluorocarboxylates in rats. Toxicol Lett 2009; 190:163-71. [PMID: 19616083 DOI: 10.1016/j.toxlet.2009.07.011] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2009] [Revised: 07/06/2009] [Accepted: 07/07/2009] [Indexed: 11/20/2022]
Abstract
Organic anion transporting polypeptide (Oatp) 1a1 has been hypothesized to play a key role in rat renal reabsorption of perfluorooctanoate (PFO). We have investigated PFO uptake kinetics in Chinese Hamster Ovary (CHO) cells that have been stably transfected with the cDNA encoding Oatp1a1. The Oatp1a1-expressing CHO cells have been validated by their Oatp1a1 gene expression, estrone-3-sulfate (E3S) uptake kinetics, and the correlation between Oatp1a1 gene expression and E3S uptake activity that were both induced by the treatment of sodium butyrate. Oatp1a1-mediated PFO uptake underwent a saturable process with a K(m) value of 162.2+/-20.2microM, which was effectively inhibited by known Oatp1a1 substrates sulfobromophthalein and taurocholate, and a major flavonoid in grapefruit juice, naringin. The inhibition of Oatp1a1-mediated E3S uptake has been compared for linear perfluorocarboxylates with carbon chain lengths ranged from 4 to 12. There was no apparent inhibition by perfluorobutanoate and perfluoropentanoate at 1mM. Inhibition was observed for perfluorohexanoate at 1mM and the level of inhibition increased as the increase of the chain length up to perfluorodecanoate. The values of apparent inhibition constant (K(i,app)) were determined for perfluorocarboxylates with chain lengths between 6 and 10. The log values of K(i,app) exhibited a negative linear relationship to the chain lengths and a positive linear relationship to the log values of the total clearance of perfluorocarboxylates in male rats. This in vitro-to-in vivo correlation strongly supports a tubular reabsorptive role of Oatp1a1 in rat renal elimination of perfluorocarboxylates. Due to the sex-dependent expression of Oatp1a1 in rat kidney, Oatp1a1-mediated tubular reabsorption is suggested to be the mechanism for the sex-dependent renal elimination of PFO in rats.
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Dorn M, Jaehme M, Weiwad M, Markwardt F, Rudolph R, Brandsch M, Bosse-Doenecke E. The role of N
-glycosylation in transport function and surface targeting of the human solute carrier PAT1. FEBS Lett 2009; 583:1631-6. [DOI: 10.1016/j.febslet.2009.04.037] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2009] [Revised: 04/21/2009] [Accepted: 04/21/2009] [Indexed: 01/07/2023]
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Soroka CJ, Xu S, Mennone A, Lam P, Boyer JL. N-Glycosylation of the alpha subunit does not influence trafficking or functional activity of the human organic solute transporter alpha/beta. BMC Cell Biol 2008; 9:57. [PMID: 18847488 PMCID: PMC2575201 DOI: 10.1186/1471-2121-9-57] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2008] [Accepted: 10/10/2008] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND The organic solute transporter (OSTalpha-OSTbeta) is a heteromeric transporter that is expressed on the basolateral membrane of epithelium in intestine, kidney, liver, testis and adrenal gland and facilitates efflux of bile acids and other steroid solutes. Both subunits are required for plasma membrane localization of the functional transporter but it is unclear how and where the subunits interact and whether glycosylation is required for functional activity. We sought to examine these questions for the human OSTalpha-OSTbeta transporter using the human hepatoma cell line, HepG2, and COS7 cells transfected with constructs of human OSTalpha-FLAG and OSTbeta-Myc. RESULTS Tunicamycin treatment demonstrated that human OSTalpha is glycosylated. In COS7 cells Western blotting identified the unglycosylated form (approximately 31 kD), the core precursor form (approximately 35 kD), and the mature, complex glycoprotein (approximately 40 kD). Immunofluorescence of both cells indicated that, in the presence of OSTbeta, the alpha subunit could still be expressed on the plasma membrane after tunicamycin treatment. Furthermore, the functional uptake of 3H-estrone sulfate was unchanged in the absence of N-glycosylation. Co-immunoprecipitation indicates that the immature form of OSTalpha interact with OSTbeta. However, immunoprecipitation of OSTbeta using an anti-Myc antibody did not co-precipitate the mature, complex glycosylated form of OSTalpha, suggesting that the primary interaction occurs early in the biosynthetic pathway and may be transient. CONCLUSION In conclusion, human OSTalpha is a glycoprotein that requires interaction with OSTbeta to reach the plasma membrane. However, glycosylation of OSTalpha is not necessary for interaction with the beta subunit or for membrane localization or function of the heteromeric transporter.
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Affiliation(s)
- Carol J Soroka
- Department of Medicine, Yale University School of Medicine, New Haven, CT, USA
| | - Shuhua Xu
- Department of Medicine, Yale University School of Medicine, New Haven, CT, USA
| | - Albert Mennone
- Department of Medicine, Yale University School of Medicine, New Haven, CT, USA
| | - Ping Lam
- Department of Medicine, Yale University School of Medicine, New Haven, CT, USA
| | - James L Boyer
- Department of Medicine, Yale University School of Medicine, New Haven, CT, USA
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Gui C, Hagenbuch B. Amino acid residues in transmembrane domain 10 of organic anion transporting polypeptide 1B3 are critical for cholecystokinin octapeptide transport. Biochemistry 2008; 47:9090-7. [PMID: 18690707 DOI: 10.1021/bi8008455] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Human organic anion transporting polypeptides (OATP) 1B1 and 1B3 are multispecific transporters that mediate uptake of amphipathic organic compounds into hepatocytes. The two OATPs contain 12 transmembrane domains (TMs) and share 80% amino acid sequence identity. Besides common substrates with OATP1B1, OATP1B3 specifically transports cholecystokinin octapeptide (CCK-8). To determine which structural domains and/or residues are important for the substrate selectivity of OATP1B3, we constructed a series of chimeric proteins between OATP1B3 and 1B1, expressed them in HEK293 cells, and determined rates of uptake of CCK-8 along with surface expression of the proteins. Replacing TM10 in OATP1B3 with TM10 of OATP1B1 resulted in a dramatically reduced degree of CCK-8 transport, indicating that TM10 is crucial for recognition and/or translocation of CCK-8. Using site-directed mutagenesis, we identified three key residues within TM10, namely, Y537, S545, and T550. When we replaced these residues with the corresponding amino acid residues found in OATP1B1, the level of CCK-8 transport was similarly low as for the replacement of the whole TM10. Kinetic experiments showed that the K m values for CCK-8 transport in the TM10 replacement and triple mutant were only 1.3 and 1.1 microM, respectively, as compared to 16.3 microM for wild-type OATP1B3. Similarly, the V max values dropped from 495.5 pmol (normalized mg) (-1) min (-1) for wild-type OATP1B3 to 13.3 and 19.0 pmol (normalized mg) (-1) min (-1) for the TM10 replacement and triple mutant, respectively. Molecular modeling indicated that two of the three identified residues might form hydrogen bonds with CCK-8. In conclusion, we have identified three amino acid residues (Y537, S545, and T550) in TM10 of OATP1B3 that are important for CCK-8 transport.
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Affiliation(s)
- Chunshan Gui
- Department of Pharmacology, Toxicology and Therapeutics, The University of Kansas Medical Center, Kansas City, Kansas 66160, USA
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