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Mosaffa F, Hadizadeh F, Fathi F, Eslami Nasab Z, Pourzahed T, Aboutorabzade SM, Ghodsi R. Synthesis and biological evaluation of novel quinoline analogs of ketoprofen as multidrug resistance protein 2 (MRP2) inhibitors. IRANIAN JOURNAL OF BASIC MEDICAL SCIENCES 2021; 24:815-825. [PMID: 34630959 PMCID: PMC8487607 DOI: 10.22038/ijbms.2021.54554.12265] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/02/2021] [Accepted: 04/10/2021] [Indexed: 11/06/2022]
Abstract
Objectives A new series of quinoline analogs of ketoprofen was designed and synthesized as multidrug resistance protein 2 (MRP2) inhibitors using ketoprofen as the lead compounds. Materials and Methods The cytotoxic activity of the compounds was evaluated againt two cancer cell lines including A2780/RCIS (MRP2-overexpressing ovarian carcinoma), A2780, drug-sensitive ovarian carcinoma using MTT assay. Compounds showing low toxicity in MTT test were selected to investigate their MRP inhibition activity. MRP2 inhibitory potency was evaluated by determination of the uptake amount of fluorescent 5-carboxy fluorescein diacetate (5-CFDA) substrate, by A2780/RCIS in the presence of the selected compounds. Mode of interaction between synthesized ligands and homology modeled MRP2 was investigated by MOE software. Results Compound 6d, a 4-carboxy quinoline possessing dimethoxy phenyl in position 2 of quinoline ring, showed the most MRP2 inhibition activity among all the quinolines and more than the reference drug ketoprofen. MRP2 inhibition activity of compound 7d was less in comparison to that of compound 6d, indicating that carboxyl group in position 4 of quinoline may interact with MRP2. Docking studies showed that compound 7d methyl ester of 6d, interacted less compared to its parent 6d, which is consistent with biological results. Conclusion This study indicates that 6- or 8-benzoyl-2-arylquinoline is a suitable scaffold to design MRP2 inhibitors. The position of benzoyl in quinoline ring is important in inhibition of MRP2. Generally, MRP2 inhibition activity of compound 7d was less in comparison to that of 6d, indicating that carboxyl group in position 4 of quinoline may interact with MRP2.
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Affiliation(s)
- Fatemeh Mosaffa
- Biotechnology Research Center, Institute of Pharmaceutical Technology, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Farzin Hadizadeh
- Biotechnology Research Center, Institute of Pharmaceutical Technology, Mashhad University of Medical Sciences, Mashhad, Iran.,Department of Medicinal Chemistry, School of Pharmacy, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Faezeh Fathi
- Biotechnology Research Center, Institute of Pharmaceutical Technology, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Zahra Eslami Nasab
- Biotechnology Research Center, Institute of Pharmaceutical Technology, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Tahereh Pourzahed
- Biotechnology Research Center, Institute of Pharmaceutical Technology, Mashhad University of Medical Sciences, Mashhad, Iran
| | | | - Razieh Ghodsi
- Biotechnology Research Center, Institute of Pharmaceutical Technology, Mashhad University of Medical Sciences, Mashhad, Iran.,Department of Medicinal Chemistry, School of Pharmacy, Mashhad University of Medical Sciences, Mashhad, Iran
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Wu H, Zhao XK, Zhu JJ. Clinical characteristics and ABCC2 genotype in Dubin-Johnson syndrome: A case report and review of the literature. World J Clin Cases 2021; 9:878-885. [PMID: 33585635 PMCID: PMC7852649 DOI: 10.12998/wjcc.v9.i4.878] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 11/20/2020] [Accepted: 12/06/2020] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Dubin-Johnson syndrome (DJS) is a benign autosomal recessive liver disease involving mutations of the ABCC2 gene. It is characterized by chronic or intermittent conjugated hyperbilirubinemia, with chronic idiopathic jaundice as the main clinical manifestation. Genetic alterations of the ABCC2 gene are commonly used for diagnosing DJS; however, the causative ABCC2 point mutation in Chinese patients remains unknown. Research on ABCC2 mutations in Chinese DJS patients is extremely rare, and the diagnosis of DJS remains limited. The routine analysis of ABCC2 mutations is helpful for the diagnosis of DJS. Here, we report the clinical characteristics and ABCC2 genotype of an adult female DJS patient. This article is to expound the discovery of more potentially pathogenic ABCC2 variants will that contribute to DJS identification.
CASE SUMMARY This study investigated a woman referred for DJS and involved clinical and genetic analyses. ABCC2 mutations were identified by next-generation sequencing (NGS). The patient showed intermittent jaundice and conjugated hyper-bilirubinemia. Histopathological examinations were consistent with the typical phenotype of DJS. Genetic diagnostic analysis revealed an ABCC2 genotype exhibiting a pathogenic variant, namely c.2443C>T (p.Arg815*), which has not been reported previously in the domestic or foreign literature.
CONCLUSION Pathogenic ABCC2 mutations play an important role in the diagnosis of DJS, especially in patients with atypical presentations. Currently, NGS is used in the routine analysis of DJS cases and such tests of further cases will better illuminate the relationship between various genotypes and phenotypes of DJS.
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Affiliation(s)
- Huan Wu
- Department of Infectious Diseases, The Affiliated Hospital of Guizhou Medical University, Guiyang 550001, Guizhou Province, China
| | - Xue-Ke Zhao
- Department of Infectious Diseases, The Affiliated Hospital of Guizhou Medical University, Guiyang 550001, Guizhou Province, China
| | - Juan-Juan Zhu
- Department of Infectious Diseases, The Affiliated Hospital of Guizhou Medical University, Guiyang 550001, Guizhou Province, China
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Gräfe K, Shanmugarajah K, Zobel T, Weidtkamp-Peters S, Kleinschrodt D, Smits SHJ, Schmitt L. Cloning and expression of selected ABC transporters from the Arabidopsis thaliana ABCG family in Pichia pastoris. PLoS One 2019; 14:e0211156. [PMID: 30657786 PMCID: PMC6338384 DOI: 10.1371/journal.pone.0211156] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Accepted: 01/08/2019] [Indexed: 02/06/2023] Open
Abstract
Phytohormones play a major role in plant growth and development. They are in most cases not synthesized in their target location and hence need to be transported to the site of action, by for instance ATP-binding cassette transporters. Within the ATP-binding cassette transporter family, Pleiotropic Drug Resistance transporters are known to be involved in phytohormone transport. Interestingly, PDRs are only present in plants and fungi. In contrast to fungi, there are few biochemical studies of plant PDRs and one major reason is that suitable overexpression systems have not been identified. In this study, we evaluate the expression system Pichia pastoris for heterologous overexpression of PDR genes of the model plant Arabidopsis thaliana. We successfully cloned and expressed the potential phytohormone transporters PDR2 and PDR8 in P. pastoris. Sucrose gradient centrifugation confirmed that the overexpressed proteins were correctly targeted to the plasma membrane of P. pastoris and initial functional studies demonstrated ATPase activity for WBC1. However, difficulties in cloning and heterologous overexpression might be particular obstacles of the PDR family, since cloning and overexpression of White Brown Complex 1, a half-size transporter of the same ABCG subfamily with comparable domain organization, was more easily achieved. We present strategies and highlight critical factors to successfully clone plant PDR genes and heterologously expressed in P. pastoris.
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Affiliation(s)
- Katharina Gräfe
- Institute of Biochemistry, Heinrich Heine University, Düsseldorf, Germany
- Cluster of Excellence on Plant Sciences, Heinrich Heine University, Düsseldorf, Germany
| | - Kalpana Shanmugarajah
- Institute of Biochemistry, Heinrich Heine University, Düsseldorf, Germany
- Cluster of Excellence on Plant Sciences, Heinrich Heine University, Düsseldorf, Germany
| | - Thomas Zobel
- Center for Advanced Imaging, Heinrich Heine University, Duüsseldorf, Germany
| | | | - Diana Kleinschrodt
- Institute of Biochemistry, Heinrich Heine University, Düsseldorf, Germany
- Protein Production Facility, Heinrich Heine University, Duüsseldorf, Germany
| | - Sander H. J. Smits
- Institute of Biochemistry, Heinrich Heine University, Düsseldorf, Germany
| | - Lutz Schmitt
- Institute of Biochemistry, Heinrich Heine University, Düsseldorf, Germany
- Cluster of Excellence on Plant Sciences, Heinrich Heine University, Düsseldorf, Germany
- * E-mail:
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4
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Hong M. Biochemical studies on the structure-function relationship of major drug transporters in the ATP-binding cassette family and solute carrier family. Adv Drug Deliv Rev 2017; 116:3-20. [PMID: 27317853 DOI: 10.1016/j.addr.2016.06.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Revised: 05/27/2016] [Accepted: 06/08/2016] [Indexed: 12/21/2022]
Abstract
Human drug transporters often play key roles in determining drug accumulation within cells. Their activities are often directly related to therapeutic efficacy, drug toxicity as well as drug-drug interactions. However, the progress for interpretation of their crystal structures is relatively slow. Hence, conventional biochemical studies together with computer modeling became useful manners to reveal essential structures of these membrane proteins. Over the years, quite a few structure-function relationship information had been obtained for members of the two major transporter families: the ATP-binding cassette family and the solute carrier family. Critical structural features of drug transporters include transmembrane domains, post-translational modification sites and domains for cell surface assembly and protein-protein interactions. Alterations at these important sites may affect protein stability, trafficking to the plasma membrane and/or ability of transporters to interact with substrates.
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Abstract
In the mammalian kidney, prostaglandins (PGs) are important mediators of physiologic processes, including modulation of vascular tone and salt and water. PGs arise from enzymatic metabolism of free arachidonic acid (AA), which is cleaved from membrane phospholipids by phospholipase A2 activity. The cyclooxygenase (COX) enzyme system is a major pathway for metabolism of AA in the kidney. COX are the enzymes responsible for the initial conversion of AA to PGG2 and subsequently to PGH2, which serves as the precursor for subsequent metabolism by PG and thromboxane synthases. In addition to high levels of expression of the "constitutive" rate-limiting enzyme responsible for prostanoid production, COX-1, the "inducible" isoform of cyclooxygenase, COX-2, is also constitutively expressed in the kidney and is highly regulated in response to alterations in intravascular volume. PGs and thromboxane A2 exert their biological functions predominantly through activation of specific 7-transmembrane G-protein-coupled receptors. COX metabolites have been shown to exert important physiologic functions in maintenance of renal blood flow, mediation of renin release and regulation of sodium excretion. In addition to physiologic regulation of prostanoid production in the kidney, increases in prostanoid production are also seen in a variety of inflammatory renal injuries, and COX metabolites may serve as mediators of inflammatory injury in renal disease.
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Affiliation(s)
- Raymond C Harris
- George M. O'Brien Kidney and Urologic Diseases Center and Division of Nephrology, Vanderbilt University School of Medicine and Nashville Veterans Affairs Hospital, Nashville, Tennessee, USA.
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Emi Y, Yasuda Y, Sakaguchi M. A cis-acting five-amino-acid motif controls targeting of ABCC2 to the apical plasma membrane domain. J Cell Sci 2012; 125:3133-43. [PMID: 22454528 DOI: 10.1242/jcs.099549] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
ATP-binding cassette transporter isoform C2 (ABCC2) is exclusively targeted to the apical plasma membrane of polarized cells. Although apical localization of ABCC2 in hepatocytes is crucial for the biliary excretion of a variety of metabolites, the mechanism regulating its apical targeting is poorly understood. In the present study, an apical targeting signal was identified in the first cytoplasmic loop domain (CLD1) of ABCC2 in HepG2 cells. Overexpression of CLD1 significantly disturbed the apical targeting of FLAG-ABCC2 in a competitive manner, suggesting the presence of a saturable sorting machinery in HepG2 cells. Next, deletion analysis identified a potential targeting sequence within a 20-amino-acid long peptide (aa 272-291) of CLD1. Alanine scanning mutagenesis of this region in full-length ABCC2 further narrowed down the apical targeting determinant to five amino acids, S(283)QDAL(287). Of these, S(283) and L(287) were found to be conserved among vertebrate ABCC2 orthologs. Site-directed mutagenesis showed that both S(283) and L(287) were crucial for the targeting specificity of ABCC2. Introducing this apical targeting sequence into the corresponding region of ABCC1, an exclusively basolateral protein, caused the hybrid ABCC1 to partially localize in the apical membrane. Thus, the CLD1 of ABCC2 contains a novel apical sorting determinant, and a saturable sorting machinery is present in polarized HepG2 cells.
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Affiliation(s)
- Yoshikazu Emi
- Graduate School of Life Science, University of Hyogo, Harima Science Park City, Hyogo, Japan.
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Sodani K, Patel A, Kathawala RJ, Chen ZS. Multidrug resistance associated proteins in multidrug resistance. CHINESE JOURNAL OF CANCER 2011; 31:58-72. [PMID: 22098952 PMCID: PMC3777468 DOI: 10.5732/cjc.011.10329] [Citation(s) in RCA: 185] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Multidrug resistance proteins (MRPs) are members of the C family of a group of proteins named ATP-binding cassette (ABC) transporters. These ABC transporters together form the largest branch of proteins within the human body. The MRP family comprises of 13 members, of which MRP1 to MRP9 are the major transporters indicated to cause multidrug resistance in tumor cells by extruding anticancer drugs out of the cell. They are mainly lipophilic anionic transporters and are reported to transport free or conjugates of glutathione (GSH), glucuronate, or sulphate. In addition, MRP1 to MRP3 can transport neutral organic drugs in free form in the presence of free GSH. Collectively, MRPs can transport drugs that differ structurally and mechanistically, including natural anticancer drugs, nucleoside analogs, antimetabolites, and tyrosine kinase inhibitors. Many of these MRPs transport physiologically important anions such as leukotriene C4, bilirubin glucuronide, and cyclic nucleotides. This review focuses mainly on the physiological functions, cellular resistance characteristics, and probable in vivo role of MRP1 to MRP9.
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Affiliation(s)
- Kamlesh Sodani
- Department of Pharmaceutical Sciences, St. John's University, Queens, NY 11439, USA
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Functional analysis of nonsynonymous single nucleotide polymorphisms of multidrug resistance-associated protein 2 (ABCC2). Pharmacogenet Genomics 2011; 21:506-15. [PMID: 21691255 DOI: 10.1097/fpc.0b013e328348c786] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
BACKGROUND Multidrug resistance-associated protein 2 (MRP2; ABCC2) mediates the biliary excretion of glutathione, glucuronide, and sulfate conjugates of endobiotics and xenobiotics. Single nucleotide polymorphisms (SNPs) of MRP2 contribute to interindividual variability in drug disposition and ultimately in drug response. OBJECTIVES To characterize the transport function of human wild-type (WT) MRP2 and four SNP variants, S789F, A1450T, V417I, and T1477M. METHODS The four SNP variants were expressed in Sf9 cells using recombinant baculovirus infection. The kinetic parameters [Km, (μmol/l); V(max), (pmol/mg/min); the Hill coefficient] of ATP-dependent transport of leukotriene C(4) (LTC(4)), estradiol-3-glucuronide (E(2)3G), estradiol-17β-glucuronide (E(2)17G), and tauroursodeoxycholic acid (TUDC) were determined in Sf9-derived plasma membrane vesicles. Transport activity was normalized for expression level. RESULTS The V(max) for transport activity was decreased for all substrates for S789F, and for all substrates except E(2)17G for A1450T. V417I showed decreased apparent affinity for LTC(4), E(2)3G, and E(2)17G, whereas transport was similar between wild-type (WT) and T1477M, except for a modest increase in TUDC transport. Examination of substrate-stimulated MRP2-dependent ATPase activity of S789F and A1450T, SNPs located in MRP2 nucleotide-binding domains (NBDs), demonstrated significantly decreased ATPase activity and only modestly decreased affinity for ATP compared with WT. CONCLUSION SNPs in the NBDs (S789F in the D-loop of NBD1, or A1450T near the ABC signature motif of NBD2) variably decreased the transport of all substrates. V417I in membrane spanning domain 1 selectively decreased the apparent affinity for the glutathione and glucuronide conjugated substrates, whereas the T1477M SNP in the carboxyl terminus altered only TUDC transport.
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Ardura JA, Friedman PA. Regulation of G protein-coupled receptor function by Na+/H+ exchange regulatory factors. Pharmacol Rev 2011; 63:882-900. [PMID: 21873413 DOI: 10.1124/pr.110.004176] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Many G protein-coupled receptors (GPCR) exert patterns of cell-specific signaling and function. Mounting evidence now supports the view that cytoplasmic adapter proteins contribute critically to this behavior. Adapter proteins recognize highly conserved motifs such as those for Src homology 3 (SH3), phosphotyrosine-binding (PTB), and postsynaptic density 95/discs-large/zona occludens (PDZ) docking sequences in candidate GPCRs. Here we review the behavior of the Na+/H+ exchange regulatory factor (NHERF) family of PDZ adapter proteins on GPCR signalling, trafficking, and function. Structural determinants of NHERF proteins that allow them to recognize targeted GPCRs are considered. NHERF1 and NHERF2 are capable also of modifying the assembled complex of accessory proteins such as β-arrestins, which have been implicated in regulating GPCR signaling. In addition, NHERF1 and NHERF2 modulate GPCR signaling by altering the G protein to which the receptor binds or affect other regulatory proteins that affect GTPase activity, protein kinase A, phospholipase C, or modify downstream signaling events. Small molecules targeting the site of NHERF1-GPCR interaction are being developed and may become important and selective drug candidates.
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Affiliation(s)
- Juan A Ardura
- Department of Pharmacology & Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
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Goler-Baron V, Assaraf YG. Structure and function of ABCG2-rich extracellular vesicles mediating multidrug resistance. PLoS One 2011; 6:e16007. [PMID: 21283667 PMCID: PMC3025911 DOI: 10.1371/journal.pone.0016007] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2010] [Accepted: 12/02/2010] [Indexed: 02/04/2023] Open
Abstract
Multidrug resistance (MDR) is a major impediment to curative cancer chemotherapy. The ATP-Binding Cassette transporters ABCG2, ABCB1 and ABCC2 form a unique defense network against multiple structurally and functionally distinct chemotherapeutics, thereby resulting in MDR. Thus, deciphering novel mechanisms of MDR and their overcoming is a major goal of cancer research. Recently we have shown that overexpression of ABCG2 in the membrane of novel extracellular vesicles (EVs) in breast cancer cells results in mitoxantrone resistance due to its dramatic sequestration in EVs. However, nothing is known about EVs structure, biogenesis and their ability to concentrate multiple antitumor agents. To this end, we here found that EVs are structural and functional homologues of bile canaliculi, are apically localized, sealed structures reinforced by an actin-based cytoskeleton and secluded from the extracellular milieu by the tight junction proteins occludin and ZO-1. Apart from ABCG2, ABCB1 and ABCC2 were also selectively targeted to the membrane of EVs. Moreover, Ezrin-Radixin-Moesin protein complex selectively localized to the border of the EVs membrane, suggesting a key role for the tethering of MDR pumps to the actin cytoskeleton. The ability of EVs to concentrate and sequester different antitumor drugs was also explored. Taking advantage of the endogenous fluorescence of anticancer drugs, we found that EVs-forming breast cancer cells display high level resistance to topotecan, imidazoacridinones and methotrexate via efficient intravesicular drug concentration hence sequestering them away from their cellular targets. Thus, we identified a new modality of anticancer drug compartmentalization and resistance in which multiple chemotherapeutics are actively pumped from the cytoplasm and highly concentrated within the lumen of EVs via a network of MDR transporters differentially targeted to the EVs membrane. We propose a composite model for the structure and function of MDR pump-rich EVs in cancer cells and their ability to confer multiple anticancer drug resistance.
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Affiliation(s)
- Vicky Goler-Baron
- The Fred Wyszkowski Cancer Research Laboratory, Department of Biology, Technion-Israel Institute of Technology, Haifa, Israel
| | - Yehuda G. Assaraf
- The Fred Wyszkowski Cancer Research Laboratory, Department of Biology, Technion-Israel Institute of Technology, Haifa, Israel
- * E-mail:
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Emi Y, Nomura S, Yokota H, Sakaguchi M. ATP-binding cassette transporter isoform C2 localizes to the apical plasma membrane via interactions with scaffolding protein. J Biochem 2010; 149:177-89. [PMID: 21059598 DOI: 10.1093/jb/mvq131] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
ATP-binding cassette transporter isoform C2 (ABCC2) localizes to the apical plasma membrane in polarized cells. Apical localization of ABCC2 in hepatocytes plays an important role in biliary excretion of endobiotics and xenobiotics, but the mechanism by which ABCC2 localizes to the apical membrane has not been conclusively elucidated. Here, we investigate the role of scaffolding proteins on ABCC2 localization with a focus on the function of PDZK1 (post-synaptic density 95/disk large/zonula occludens-1 domain containing 1) in regulating ABCC2 localization. The C-terminal 77 residues of ABCC2 were used to probe interacting proteins from HepG2 cells. Protein mass fingerprinting identified PDZK1 as a major interacting protein. PDZK1 associated with the plasma membrane, most likely at the apical vacuoles of HepG2 cells. Affinity pull-down assays confirmed that the C-terminal NSTKF of ABCC2 bound to the fourth PDZ domain of PDZK1. Removal of this PDZ-binding motif significantly reduced the normal apical localization of ABCC2. In HepG2 cells, overexpression of this fourth domain overcame endogenous PDZK1 and reduced the ABCC2 localization at the apical membrane with a reciprocal increase of intracellular accumulation of mislocalized ABCC2. These results suggest a possible role for an interaction between ABCC2 and PDZK1 in apical localization of ABCC2 in hepatocytes.
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Affiliation(s)
- Yoshikazu Emi
- Graduate School of Life Science, University of Hyogo, Harima Science Park City, Hyogo, Japan.
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Jemnitz K, Heredi-Szabo K, Janossy J, Ioja E, Vereczkey L, Krajcsi P. ABCC2/Abcc2: a multispecific transporter with dominant excretory functions. Drug Metab Rev 2010; 42:402-36. [PMID: 20082599 DOI: 10.3109/03602530903491741] [Citation(s) in RCA: 101] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
ABCC2/Abcc2 (MRP2/Mrp2) is expressed at major physiological barriers, such as the canalicular membrane of liver cells, kidney proximal tubule epithelial cells, enterocytes of the small and large intestine, and syncytiotrophoblast of the placenta. ABCC2/Abcc2 always localizes in the apical membranes. Although ABCC2/Abcc2 transports a variety of amphiphilic anions that belong to different classes of molecules, such as endogenous compounds (e.g., bilirubin-glucuronides), drugs, toxic chemicals, nutraceuticals, and their conjugates, it displays a preference for phase II conjugates. Phenotypically, the most obvious consequence of mutations in ABCC2 that lead to Dubin-Johnson syndrome is conjugate hyperbilirubinemia. ABCC2/Abcc2 harbors multiple binding sites and displays complex transport kinetics.
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Affiliation(s)
- Katalin Jemnitz
- Chemical Research Center, Institute of Biomolecular Chemistry, HAS, Budapest, Hungary
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Cruz LN, Guerra MT, Kruglov E, Mennone A, Garcia CRS, Chen J, Nathanson MH. Regulation of multidrug resistance-associated protein 2 by calcium signaling in mouse liver. Hepatology 2010; 52:327-37. [PMID: 20578149 PMCID: PMC3025771 DOI: 10.1002/hep.23625] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
UNLABELLED Multidrug resistance associated protein 2 (Mrp2) is a canalicular transporter responsible for organic anion secretion into bile. Mrp2 activity is regulated by insertion into the plasma membrane; however, the factors that control this are not understood. Calcium (Ca(2+)) signaling regulates exocytosis of vesicles in most cell types, and the type II inositol 1,4,5-triphosphate receptor (InsP(3)R2) regulates Ca(2+) release in the canalicular region of hepatocytes. However, the role of InsP(3)R2 and of Ca(2+) signals in canalicular insertion and function of Mrp2 is not known. The aim of this study was to determine the role of InsP(3)R2-mediated Ca(2+) signals in targeting Mrp2 to the canalicular membrane. Livers, isolated hepatocytes, and hepatocytes in collagen sandwich culture from wild-type (WT) and InsP(3)R2 knockout (KO) mice were used for western blots, confocal immunofluorescence, and time-lapse imaging of Ca(2+) signals and of secretion of a fluorescent organic anion. Plasma membrane insertion of green fluorescent protein (GFP)-Mrp2 expressed in HepG2 cells was monitored by total internal reflection microscopy. InsP(3)R2 was concentrated in the canalicular region of WT mice but absent in InsP(3)R2 KO livers, whereas expression and localization of InsP(3)R1 was preserved, and InsP(3)R3 was absent from both WT and KO livers. Ca(2+) signals induced by either adenosine triphosphate (ATP) or vasopressin were impaired in hepatocytes lacking InsP(3)R2. Canalicular secretion of the organic anion 5-chloromethylfluorescein diacetate (CMFDA) was reduced in KO hepatocytes, as well as in WT hepatocytes treated with 1,2-bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA). Moreover, the choleretic effect of tauroursodeoxycholic acid (TUDCA) was impaired in InsP(3)R2 KO mice. Finally, ATP increased GFP-Mrp2 fluorescence in the plasma membrane of HepG2 cells, and this also was reduced by BAPTA. CONCLUSION InsP(3)R2-mediated Ca(2+) signals enhance organic anion secretion into bile by targeting Mrp2 to the canalicular membrane.
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Affiliation(s)
- Laura N. Cruz
- Section of Digestive Diseases, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT,Department of Parasitology, University of Saão Paulo, Saão Paulo, Brazil
| | - Mateus T. Guerra
- Section of Digestive Diseases, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT,Department of Physiology and Biophysics, Federal University of Minas Gerais, Belo Horizonte, Brazil
| | - Emma Kruglov
- Section of Digestive Diseases, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT
| | - Albert Mennone
- Section of Digestive Diseases, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT
| | | | - Ju Chen
- Department of Medicine, University of California, San Diego, CA
| | - Michael H. Nathanson
- Section of Digestive Diseases, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT
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Li M, Wang W, Soroka CJ, Mennone A, Harry K, Weinman EJ, Boyer JL. NHERF-1 binds to Mrp2 and regulates hepatic Mrp2 expression and function. J Biol Chem 2010; 285:19299-307. [PMID: 20404332 DOI: 10.1074/jbc.m109.096081] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Multidrug resistance-associated protein 2 (Mrp2, Abcc2) is an ATP-binding cassette transporter localized at the canalicular membrane of hepatocytes that plays an important role in bile formation and detoxification. Prior in vitro studies suggest that Mrp2 can bind to Na(+)/H(+) exchanger regulatory factor 1 (NHERF-1), a PDZ protein that cross-links membrane proteins to actin filaments. However the role of NHERF-1 in the expression and functional regulation of Mrp2 remains largely unknown. Here we examine the interaction of Mrp2 and NHERF-1 and its physiological significance in HEK293 cells and NHERF-1 knock-out mice. Mrp2 co-precipitated with NHERF-1 in co-transfected HEK293 cells, an interaction that required the PDZ-binding motif of Mrp2. In NHERF-1(-/-) mouse liver, Mrp2 mRNA was unchanged but Mrp2 protein was reduced in whole cell lysates and membrane-enriched fractions to approximately 50% (p < 1 x 10(-6)) and approximately 70% (p < 0.05), respectively, compared with wild-type mice, suggesting that the down-regulation of Mrp2 expression was caused by post-transcriptional events. Mrp2 remained localized at the apical/canalicular membrane of NHERF-1(-/-) mouse hepatocytes, although its immunofluorescent labeling was noticeably weaker. Bile flow in NHERF-1(-/-) mice was reduced to approximately 70% (p < 0.001) in association with a 50% reduction in glutathione excretion (p < 0.05) and a 60% reduction in glutathione-methylfluorescein (GS-MF) excretion in isolated mouse hepatocyte (p < 0.01). Bile acid and bilirubin excretion remained unchanged compared with wild-type mice. These findings strongly suggest that NHERF-1 binds to Mrp2, and plays a critical role in the canalicular expression of Mrp2 and its function as a determinant of glutathione-dependent, bile acid-independent bile flow.
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Affiliation(s)
- Man Li
- Liver Center, Yale University School of Medicine, New Haven, Connecticut 06520, USA
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15
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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: 558] [Impact Index Per Article: 39.9] [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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16
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Minami S, Ito K, Honma M, Ikebuchi Y, Anzai N, Kanai Y, Nishida T, Tsukita S, Sekine S, Horie T, Suzuki H. Posttranslational regulation of Abcc2 expression by SUMOylation system. Am J Physiol Gastrointest Liver Physiol 2009; 296:G406-13. [PMID: 19074644 DOI: 10.1152/ajpgi.90309.2008] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The ATP-binding cassette transporter family C 2 (Abcc2) is a member of efflux transporters involved in the biliary excretion of organic anions from hepatocytes. Posttranslational regulation of Abcc2 has been implicated, although the molecular mechanism is not fully understood. In the present study, we performed yeast two-hybrid screening to identify novel protein(s) that particularly interacts with the linker region of Abcc2 located between the NH(2)-terminal nucleotide binding domain and the last membrane-spanning domain. The screening resulted in the identification of a series of small ubiquitin-like modifier (SUMO)-related enzymes and their substrates. In yeast experiments, all of these interactions were abolished by substituting the putative SUMO consensus site in the linker region (IKKE) in Abcc2 to IRKE. In vitro SUMOylation experiments confirmed that the Abcc2 linker was a substrate of Ubc9-mediated SUMOylation. It was also found that the IKKE sequence is the target of SUMOylation, since a mutant with IKKE is substituted by IRKE was not SUMOylated. Furthermore, we demonstrated for the first time that Abcc2, endogenously expressed in rat hepatoma-derived McARH7777 cells, is SUMOylated. Suppression of endogenous Ubc9 by small interfering RNA resulted in a selective 30% reduction in Abcc2 protein expression in the postnuclear supernatant, whereas subcellular localization of Abcc2 confirmed by semiquantitative immunofluorescence analysis was minimally affected. This is the first demonstration showing the regulation of ABC transporter expression by SUMOylation.
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Affiliation(s)
- Satoko Minami
- Department of Pharmacy, The University of Tokyo Hospital, Faculty of Medicine, The University of Tokyo, Tokyo, Japan
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17
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Zachos NC, Hodson C, Kovbasnjuk O, Li X, Thelin WR, Cha B, Milgram S, Donowitz M. Elevated intracellular calcium stimulates NHE3 activity by an IKEPP (NHERF4) dependent mechanism. Cell Physiol Biochem 2008; 22:693-704. [PMID: 19088451 DOI: 10.1159/000185553] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/24/2008] [Indexed: 01/09/2023] Open
Abstract
The ileal brush border (BB) contains four evolutionarily related multi-PDZ domain proteins including NHERF1, NHERF2, PDZK1 (NHERF3) and IKEPP (NHERF4). Why multiple related PDZ proteins are in a similar location in the same cell is unknown. However, some specificity in regulation of NHE3 activity has been identified. For example, elevated intracellular Ca(2+) ([Ca(2+)](i)) inhibition of NHE3 is reconstituted by NHERF2 but not NHERF1, and involves the formation of large NHE3 complexes. To further evaluate the specificity of the NHERF family in calcium regulation of NHE3 activity, the current study determined whether the four PDZ domain containing protein IKEPP reconstitutes elevated [Ca(2+)](i) regulation of NHE3. In vitro, IKEPP bound to the F2 region (aa 590-667) of NHE3 in overlay assays, which is the same region where NHERF1 and NHERF2 bind. PS120 cells lack endogenous NHE3 and IKEPP. Treatment of PS120/NHE3/IKEPP cells (stably transfected with NHE3 and IKEPP) with the Ca(2+) ionophore, 4-Br-A23187 (0.5 microM), stimulated NHE3 V(max) activity by approximately 40%. This was associated with an increase in plasma membrane expression of NHE3 by a similar amount. NHE3 activity and surface expression were unaffected by A23187 in PS120/NHE3 cells lacking IKEPP. Based on sucrose density gradient centrifugation, IKEPP was also shown to exist in large complexes, some of which overlap in size with NHE3, and the size of both NHE3 and IKEPP complexes decreased in parallel after [Ca(2+)](i) elevation. FRET experiments on fixed cells demonstrated that IKEPP and NHE3 directly associated at an intracellular site. Elevating [Ca(2+)](i) decreased this intracellular NHE3 and IKEPP association. In summary: (1) In the presence of IKEPP, elevated [Ca(2+)](i) stimulates NHE3 activity. This was associated with increased expression of NHE3 in the plasma membrane as well as a shift to smaller sizes of NHE3 and IKEPP containing complexes. (2) IKEPP directly binds NHE3 at its F2 C-terminal domain and directly associates with NHE3 in vivo (FRET). (3) Elevated [Ca(2+)](i) decreased the association of IKEPP and NHE3 in an intracellular compartment. Based on which NHERF family member is expressed in PS120 cells, elevated [Ca(2+)](i) stimulates (IKEPP), inhibits (NHERF2) or does not affect (NHERF1) NHE3 activity. This demonstrates that regulation of NHE3 depends on the nature of the NHERF family member associating with NHE3 and the accompanying NHE3 complexes.
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Affiliation(s)
- Nicholas C Zachos
- Department of Medicine and Physiology, Hopkins Center for Epithelial Disorders, Johns Hopkins University School of Medicine, Baltimore, MD 21205-2195, USA
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18
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Bandler PE, Westlake CJ, Grant CE, Cole SPC, Deeley RG. Identification of regions required for apical membrane localization of human multidrug resistance protein 2. Mol Pharmacol 2008; 74:9-19. [PMID: 18381564 DOI: 10.1124/mol.108.045674] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2023] Open
Abstract
Multidrug resistance proteins MRP1 and MRP2 transport a wide range of endo- and xenobiotics. However, with the exception of certain parts of the brain, MRP1 traffics to basolateral membranes of polarized cells, whereas MRP2 is apical in location and thus it is particularly important for systemic elimination of such compounds. Different regions of MRP1 and MRP2 seem to target them to their respective membrane locations. In addition to two "core" membrane spanning domains (MSDs) characteristic of ATP-binding cassette transporters, MRP1 and MRP2 have a third NH2-terminal MSD (MSD0), which is not required for basolateral targeting of MRP1, or for transport of at least some substrates. Here, we demonstrate that all elements necessary for apical targeting of MRP2 reside in MSD0 and the adjacent cytoplasmic loop (CL) 3. Furthermore, we show that this region of MRP2 can target the core of MRP1 to an exclusively apical location. Within MRP2 CL3, we identified a lysine-rich element that is essential for apical targeting. When introduced into MRP1, this element alone is sufficient to result in partial apical localization. However, exclusive targeting to the apical membrane seems to require the integrity of the entire region encompassing MSD0 and CL3 of MRP2. Because CL3 of MRP1 is critical for binding, transport, or both of several compounds, we also examined the function of hybrids containing all, or portions of MRP2 MSD0 and CL3. Our results indicate that CL3 is important for interaction with both the glutathione and glucuronide conjugates tested, but that different regions may be involved.
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Affiliation(s)
- Paul E Bandler
- Division of Cancer Biology and Genetics, Queen's University Cancer Research Institute, Kingston, ON, Canada
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19
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Nies AT, Herrmann E, Brom M, Keppler D. Vectorial transport of the plant alkaloid berberine by double-transfected cells expressing the human organic cation transporter 1 (OCT1, SLC22A1) and the efflux pump MDR1 P-glycoprotein (ABCB1). Naunyn Schmiedebergs Arch Pharmacol 2007; 376:449-61. [PMID: 18157518 DOI: 10.1007/s00210-007-0219-x] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2007] [Accepted: 11/09/2007] [Indexed: 12/27/2022]
Abstract
An important function of hepatocytes is the biliary elimination of endogenous and xenobiotic small molecules, many of which are organic cations. To study this vectorial transport of organic cations, we constructed a double-transfected Madin-Darby canine kidney strain II (MDCKII) cell line permanently expressing the human organic cation transporter 1 (OCT1, SLC22A1) in the basolateral membrane and MDR1 P-glycoprotein (MDR1 P-gp, ABCB1), an adenosine triphosphate (ATP)-dependent efflux pump for organic cations, in the apical membrane. Additionally, MDCKII single transfectants stably expressing OCT1, MDR1 P-gp, or human organic cation transporter 2 (OCT2, SLC22A2) were generated. Antisera directed against OCT1 or OCT2 specifically detected OCT1 in the basolateral membrane of human hepatocytes, OCT2 in tubular epithelial cells of human kidney, and the respective recombinant transporter in the basolateral membrane of MDCKII transfectants. We identified the lipophilic organic cation berberine, a fluorescent plant alkaloid exhibiting a broad range of biological activities, as substrate of OCT1 and OCT2 with Michaelis-Menten constants of 14.8 microM and 4.4 microM, respectively. Berberine also inhibited the uptake of the prototypic cations tetraethylammonium and 1-methyl-4-phenylpyridinium by MDCK-OCT1 and MDCK-OCT2 transfectants. When transfected cells were grown polarized on permeable filter supports, berberine was transferred from the basolateral to the apical compartments many times faster by MDCK-OCT1/MDR1 P-gp double transfectants than by MDCK-OCT1 or MDCK-MDR1 P-gp single transfectants. The specific MDR1 P-gp inhibitor, zosuquidar trihydrochloride (LY335979), strongly inhibited berberine efflux into the apical compartment. The MDCK-OCT1/MDR1 P-gp double transfectants may be useful to identify additional cationic substrates and inhibitors of OCT1 and MDR1 P-gp, including drug candidates.
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Affiliation(s)
- Anne T Nies
- Division of Tumor Biochemistry, German Cancer Research Center, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany.
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Jedlitschky G, Hoffmann U, Kroemer HK. Structure and function of the MRP2 (ABCC2) protein and its role in drug disposition. Expert Opin Drug Metab Toxicol 2007; 2:351-66. [PMID: 16863439 DOI: 10.1517/17425255.2.3.351] [Citation(s) in RCA: 161] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The multi-drug resistance protein 2 (MRP2; ABCC2) is an ATP-binding cassette transporter playing an important role in detoxification and chemoprotection by transporting a wide range of compounds, especially conjugates of lipophilic substances with glutathione, glucuronate and sulfate, which are collectively known as phase II products of biotransformation. In addition, MRP2 can also transport uncharged compounds in cotransport with glutathione, and thus can modulate the pharmacokinetics of many drugs. The other way around, its expression and activity are also altered by certain drugs and disease states. Unlike other members of the MRP/ABCC family, MRP2 is specifically expressed on the apical membrane domain of polarised cells as hepatocytes, renal proximal tubular cells, enterocytes and syncytiotrophoblasts of the placenta. Several naturally occurring mutations leading to the absence of functional MRP2 protein from the apical membrane have been described causing the human Dubin-Johnson syndrome associated with conjugated hyperbilirubinaemia. Experimental mutation studies have revealed critical amino acids for substrate binding in the MRP2 molecule. This review is, therefore, focused on the structure and function of MRP2, the substrates transported and the clinical relevance of MRP2.
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Affiliation(s)
- Gabriele Jedlitschky
- Research Center of Pharmacology and Experimental Therapeutics, Department of Pharmacology, Ernst-Moritz-Arndt-University Greifswald, Friedrich-Loeffler-Str. 23d, 17487 Greifswald, Germany.
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21
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Ramnarayanan SP, Cheng CA, Bastaki M, Tuma PL. Exogenous MAL reroutes selected hepatic apical proteins into the direct pathway in WIF-B cells. Mol Biol Cell 2007; 18:2707-15. [PMID: 17494867 PMCID: PMC1924826 DOI: 10.1091/mbc.e07-02-0096] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Unlike simple epithelial cells that directly target newly synthesized glycophosphatidylinositol (GPI)-anchored and single transmembrane domain (TMD) proteins from the trans-Golgi network to the apical membrane, hepatocytes use an indirect pathway: proteins are delivered to the basolateral domain and then selectively internalized and transcytosed to the apical plasma membrane. Myelin and lymphocyte protein (MAL) and MAL2 have been identified as regulators of direct and indirect apical delivery, respectively. Hepatocytes lack endogenous MAL consistent with the absence of direct apical targeting. Does MAL expression reroute hepatic apical residents into the direct pathway? We found that MAL expression in WIF-B cells induced the formation of cholesterol and glycosphingolipid-enriched Golgi domains that contained GPI-anchored and single TMD apical proteins; polymeric IgA receptor (pIgA-R), polytopic apical, and basolateral resident distributions were excluded. Basolateral delivery of newly synthesized apical residents was decreased in MAL-expressing cells concomitant with increased apical delivery; pIgA-R and basolateral resident delivery was unchanged. These data suggest that MAL rerouted selected hepatic apical proteins into the direct pathway.
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Affiliation(s)
| | - Christina A. Cheng
- *Department of Biology, The Catholic University of America, Washington, DC 20064; and
| | - Maria Bastaki
- Graduate Environmental Studies Unit, The Evergreen State College, Olympia, WA 98505
| | - Pamela L. Tuma
- *Department of Biology, The Catholic University of America, Washington, DC 20064; and
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23
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Cnubben NHP, Wortelboer HM, van Zanden JJ, Rietjens IMCM, van Bladeren PJ. Metabolism of ATP-binding cassette drug transporter inhibitors: complicating factor for multidrug resistance. Expert Opin Drug Metab Toxicol 2006; 1:219-32. [PMID: 16922638 DOI: 10.1517/17425255.1.2.219] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Membrane transport proteins belonging to the ATP-binding cassette (ABC) family of transport proteins play a central role in the defence of organisms against toxic compounds, including anticancer drugs. However, for compounds that are designed to display a toxic effect, this defence system diminishes their effectiveness. This is typically the case in the development of cellular resistance to anticancer drugs. Inhibitors of these transporters are thus potentially useful tools to reverse this transporter-mediated cellular resistance to anticancer drugs and, eventually, to enhance the effectiveness of the treatment of patients with drug-resistant cancer. This review highlights the various types of inhibitors of several multidrug resistance-related ABC proteins, and demonstrates that the metabolism of inhibitors, as illustrated by recent data obtained for various natural compound inhibitors, may have considerable implications for their effect on drug transport and their potential for treatment of drug resistance.
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24
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Chmelar RS, Nathanson NM. Identification of a novel apical sorting motif and mechanism of targeting of the M2 muscarinic acetylcholine receptor. J Biol Chem 2006; 281:35381-96. [PMID: 16968700 DOI: 10.1074/jbc.m605954200] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Previous studies have shown that the M2 receptor is localized at steady state to the apical domain in Madin-Darby canine kidney (MDCK) epithelial cells. In this study, we identify the molecular determinants governing the localization and the route of apical delivery of the M2 receptor. First, by confocal analysis of a transiently transfected glycosylation mutant in which the three putative glycosylation sites were mutated, we determined that N-glycans are not necessary for the apical targeting of the M2 receptor. Next, using a chimeric receptor strategy, we found that two independent sequences within the M2 third intracellular loop can confer apical targeting to the basolaterally targeted M4 receptor, Val270-Lys280 and Lys280-Ser350. Experiments using Triton X-100 extraction followed by OptiPrep density gradient centrifugation and cholera toxin beta-subunit-induced patching demonstrate that apical targeting is not because of association with lipid rafts. 35S-Metabolic labeling experiments with domain-specific surface biotinylation as well as immunocytochemical analysis of the time course of surface appearance of newly transfected confluent MDCK cells expressing FLAG-M2-GFP demonstrate that the M2 receptor achieves its apical localization after first appearing on the basolateral domain. Domain-specific application of tannic acid of newly transfected cells indicates that initial basolateral plasma membrane expression is required for subsequent apical localization. This is the first demonstration that a G-protein-coupled receptor achieves its apical localization in MDCK cells via transcytosis.
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Affiliation(s)
- Renée S Chmelar
- Department of Pharmacology, University of Washington School of Medicine, Seattle, Washington 98195-7750, USA
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25
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Deeley RG, Westlake C, Cole SPC. Transmembrane transport of endo- and xenobiotics by mammalian ATP-binding cassette multidrug resistance proteins. Physiol Rev 2006; 86:849-99. [PMID: 16816140 DOI: 10.1152/physrev.00035.2005] [Citation(s) in RCA: 533] [Impact Index Per Article: 29.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Multidrug Resistance Proteins (MRPs), together with the cystic fibrosis conductance regulator (CFTR/ABCC7) and the sulfonylurea receptors (SUR1/ABCC8 and SUR2/ABCC9) comprise the 13 members of the human "C" branch of the ATP binding cassette (ABC) superfamily. All C branch proteins share conserved structural features in their nucleotide binding domains (NBDs) that distinguish them from other ABC proteins. The MRPs can be further divided into two subfamilies "long" (MRP1, -2, -3, -6, and -7) and "short" (MRP4, -5, -8, -9, and -10). The short MRPs have a typical ABC transporter structure with two polytropic membrane spanning domains (MSDs) and two NBDs, while the long MRPs have an additional NH2-terminal MSD. In vitro, the MRPs can collectively confer resistance to natural product drugs and their conjugated metabolites, platinum compounds, folate antimetabolites, nucleoside and nucleotide analogs, arsenical and antimonial oxyanions, peptide-based agents, and, under certain circumstances, alkylating agents. The MRPs are also primary active transporters of other structurally diverse compounds, including glutathione, glucuronide, and sulfate conjugates of a large number of xeno- and endobiotics. In vivo, several MRPs are major contributors to the distribution and elimination of a wide range of both anticancer and non-anticancer drugs and metabolites. In this review, we describe what is known of the structure of the MRPs and the mechanisms by which they recognize and transport their diverse substrates. We also summarize knowledge of their possible physiological functions and evidence that they may be involved in the clinical drug resistance of various forms of cancer.
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Affiliation(s)
- Roger G Deeley
- Division of Cancer Biology and Genetics, Cancer Research Institute and Department of Biochemistry, Queen's University Kingdom, Ontario, Canada.
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Nies AT, Keppler D. The apical conjugate efflux pump ABCC2 (MRP2). Pflugers Arch 2006; 453:643-59. [PMID: 16847695 DOI: 10.1007/s00424-006-0109-y] [Citation(s) in RCA: 252] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2006] [Accepted: 05/29/2006] [Indexed: 12/14/2022]
Abstract
ABCC2 is a member of the multidrug resistance protein subfamily localized exclusively to the apical membrane domain of polarized cells, such as hepatocytes, renal proximal tubule epithelia, and intestinal epithelia. This localization supports the function of ABCC2 in the terminal excretion and detoxification of endogenous and xenobiotic organic anions, particularly in the unidirectional efflux of substances conjugated with glutathione, glucuronate, or sulfate, as exemplified by leukotriene C(4), bilirubin glucuronosides, and some steroid sulfates. The hepatic ABCC2 pump contributes to the driving forces of bile flow. Acquired or hereditary deficiency of ABCC2, the latter known as Dubin-Johnson syndrome in humans, causes an increased concentration of bilirubin glucuronosides in blood because of their efflux from hepatocytes via the basolateral ABCC3, which compensates for the deficiency in ABCC2-mediated apical efflux. In this article we provide an overview on the molecular characteristics of ABCC2 and its expression in various tissues and species. We discuss the transcriptional and posttranscriptional regulation of ABCC2 and review approaches to the functional analysis providing information on its substrate specificity. A comprehensive list of sequence variants in the human ABCC2 gene summarizes predicted and proven functional consequences, including variants leading to Dubin-Johnson syndrome.
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Affiliation(s)
- Anne T Nies
- Division of Tumor Biochemistry, German Cancer Research Center, Heidelberg, Germany.
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Kuwano R, Miyashita A, Arai H, Asada T, Imagawa M, Shoji M, Higuchi S, Urakami K, Kakita A, Takahashi H, Tsukie T, Toyabe S, Akazawa K, Kanazawa I, Ihara Y. Dynamin-binding protein gene on chromosome 10q is associated with late-onset Alzheimer's disease. Hum Mol Genet 2006; 15:2170-82. [PMID: 16740596 DOI: 10.1093/hmg/ddl142] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The apolipoprotein E (APOE) gene has been consistently shown to be a major genetic risk factor; however, all cases of Alzheimer's disease (AD) cannot be attributed to the epsilon4 variant of APOE, because about half of AD patients have the APOE-epsilon3*3 genotype. To identify an additional genetic risk factor(s), we performed large-scale single nucleotide polymorphism (SNP)-based association analysis of 1526 late-onset AD patients and 1666 control subjects in a Japanese population. We prepared two independent sets consisting of exploratory and validation samples, respectively, with only the APOE-epsilon3*3 genotype, and first carried out genotyping for the exploratory set with 1206 SNPs in the region between 60 and 107 Mb on chromosome 10q that is implicated by linkage studies as containing an AD susceptibility locus. Thirty-five SNPs that showed significant values (P<0.01) were followed-up to detect any association with the validation samples. Finally, six SNPs exhibited replicated significant associations (P=0.000035-0.00048) on meta-analysis of both sets. These SNPs were clustered in a locus spanning 220 kb at genomic position 101 Mb, and three of the six SNPs were located in the dynamin-binding protein (DNMBP) gene. Quantitative real-time RT-PCR analysis demonstrated that neuropathologically confirmed AD brains exhibit a significant reduction of DNMBP mRNA compared with age-matched ones (P<0.0169). Thus, we confirmed the association of DNMBP with AD individuals with the APOE-epsilon3*3 genotype or lacking the epsilon4 allele, and DNMBP may be one of the susceptibility genes for AD.
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Affiliation(s)
- Ryozo Kuwano
- Genome Science Branch, Center for Bioresource-Based Researches, Brain Research Institute, Niigata University, Niigata, Japan.
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Kato Y, Watanabe C, Tsuji A. Regulation of drug transporters by PDZ adaptor proteins and nuclear receptors. Eur J Pharm Sci 2006; 27:487-500. [PMID: 16376527 DOI: 10.1016/j.ejps.2005.11.006] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2005] [Revised: 11/14/2005] [Accepted: 11/15/2005] [Indexed: 12/25/2022]
Abstract
Drug transporters have been suggested to be involved in various aspects of pharmacokinetics. Identification and characterization of drug transporters have given us a scientific basis for understanding drug disposition, as well as the molecular mechanisms of drug interaction and inter-individual/inter-species differences. On the other hand, regulatory mechanisms of drug transporters are still poorly understood, and information is limited to induction and down-regulation of drug transporters by various microsomal enzyme inducers. Little is known about the molecular machinery that directly interacts with the drug transporters. As a first step to clarify such molecular mechanisms, recent studies have identified PDZ (PSD-95/Discs-large/ZO-1) domain-containing proteins that directly interact with the so-called PDZ binding motif located at the C-terminus of drug transporters. Some of the PDZ proteins have been suggested to regulate transporters via at least two pathways, i.e. stabilization at the cell-surface and direct modulation of transporter function. Therefore, it is possible that membrane transport of therapeutic agents is not only governed by the drug transporters themselves, but also indirectly by PDZ proteins. The PDZ proteins are classified as a family, the members of which are thought to have distinct, but also redundant physiological roles. The purpose of this review article is to summarize the available knowledge on protein interactions and functional modulation of drug transporters.
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Affiliation(s)
- Yukio Kato
- Division of Pharmaceutical Sciences, Graduate School of Natural Science and Technology, Kanazawa University, Kakuma, Kanazawa, Ishikawa 920-1192, Japan
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29
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Bortfeld M, Rius M, König J, Herold-Mende C, Nies AT, Keppler D. Human multidrug resistance protein 8 (MRP8/ABCC11), an apical efflux pump for steroid sulfates, is an axonal protein of the CNS and peripheral nervous system. Neuroscience 2005; 137:1247-57. [PMID: 16359813 DOI: 10.1016/j.neuroscience.2005.10.025] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2005] [Revised: 10/04/2005] [Accepted: 10/07/2005] [Indexed: 11/24/2022]
Abstract
Dehydroepiandrosterone 3-sulfate and other neurosteroids are synthesized in the CNS and peripheral nervous system where they may modulate neuronal excitability by interacting with ligand-gated ion channels. For this modulatory activity, neurosteroids have to be locally released from either neurons or glial cells. We here identify the integral membrane protein ABCC11 (multidrug resistance protein 8) as an ATP-dependent efflux pump for steroid sulfates, including dehydroepiandrosterone 3-sulfate, and localize it to axons of the human CNS and peripheral nervous system. ABCC11 mRNA was detected in human brain by real-time polymerase chain reaction. Antibodies raised against ABCC11 served to detect the protein in brain by immunoblotting and immunofluorescence microscopy. ABCC11 was preferentially found in the white matter of the brain and co-localized with neurofilaments indicating that it is an axonal protein. Additionally, ABCC11 was localized to axons of the peripheral nervous system. For functional studies, ABCC11 was expressed in polarized Madin-Darby canine kidney cells where it was sorted to the apical membrane. This apical sorting is in accordance with the localization of ABCC11 to the axonal membrane of neurons. Inside-out plasma membrane vesicles containing recombinant ABCC11 mediated ATP-dependent transport of dehydroepiandrosterone 3-sulfate with a Km value of 21 microM. This transport function together with the localization of the ABCC11 protein in vicinity to GABAA receptors is consistent with a role of ABCC11 in dehydroepiandrosterone 3-sulfate release from neurons to sites of dehydroepiandrosterone 3-sulfate-mediated receptor modulation. Our findings may provide a basis for the characterization of mutations in the human ABCC11 gene and their linkage with neurological disorders.
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Affiliation(s)
- M Bortfeld
- Division of Tumor Biochemistry, German Cancer Research Center, University of Heidelberg, Im Neuenheimer Feld 280, D-69120 Heidelberg, Germany
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30
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Biemans-Oldehinkel E, Doeven MK, Poolman B. ABC transporter architecture and regulatory roles of accessory domains. FEBS Lett 2005; 580:1023-35. [PMID: 16375896 DOI: 10.1016/j.febslet.2005.11.079] [Citation(s) in RCA: 170] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2005] [Revised: 11/30/2005] [Accepted: 11/30/2005] [Indexed: 10/25/2022]
Abstract
We present an overview of the architecture of ATP-binding cassette (ABC) transporters and dissect the systems in core and accessory domains. The ABC transporter core is formed by the transmembrane domains (TMDs) and the nucleotide binding domains (NBDs) that constitute the actual translocator. The accessory domains include the substrate-binding proteins, that function as high affinity receptors in ABC type uptake systems, and regulatory or catalytic domains that can be fused to either the TMDs or NBDs. The regulatory domains add unique functions to the transporters allowing the systems to act as channel conductance regulators, osmosensors/regulators, and assemble into macromolecular complexes with specific properties.
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Affiliation(s)
- Esther Biemans-Oldehinkel
- Department of Biochemistry, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
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31
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Ito K, Suzuki H, Horie T, Sugiyama Y. Apical/Basolateral Surface Expression of Drug Transporters and its Role in Vectorial Drug Transport. Pharm Res 2005; 22:1559-77. [PMID: 16180115 DOI: 10.1007/s11095-005-6810-2] [Citation(s) in RCA: 111] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2005] [Accepted: 06/21/2005] [Indexed: 01/10/2023]
Abstract
It is well known that transporter proteins play a key role in governing drug absorption, distribution, and elimination in the body, and, accordingly, they are now considered as causes of drug-drug interactions and interindividual differences in pharmacokinetic profiles. Polarized tissues directly involved in drug disposition (intestine, kidney, and liver) and restricted distribution to naive sanctuaries (blood-tissue barriers) asymmetrically express a variety of drug transporters on the apical and basolateral sides, resulting in vectorial drug transport. For example, the organic anion transporting polypeptide (OATP) family on the sinusoidal (basolateral) membrane and multidrug resistance-associated protein 2 (MRP2/ABCC2) on the apical bile canalicular membrane of hepatocytes take up and excrete organic anionic compounds from blood to bile. Such vectorial transcellular transport is fundamentally attributable to the asymmetrical distribution of transporter molecules in polarized cells. Besides the apical/basolateral sorting direction, distribution of the transporter protein between the membrane surface (active site) and the intracellular fraction (inactive site) is of practical importance for the quantitative evaluation of drug transport processes. The most characterized drug transporter associated with this issue is MRP2 on the hepatocyte canalicular (apical) membrane, and it is linked to a genetic disease. Dubin-Johnson syndrome is sometimes caused by impaired canalicular surface expression of MRP2 by a single amino acid substitution. Moreover, single nucleotide polymorphisms in OATP-C/SLC21A6 (SLCO1B1) also affect membrane surface expression, and actually lead to the altered pharmacokinetic profile of pravastatin in healthy subjects. In this review article, the asymmetrical transporter distribution and altered surface expression in polarized tissues are discussed.
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Affiliation(s)
- Kousei Ito
- Department of Biopharmaceutics, Graduate School of Pharmaceutical Sciences, Chiba University, Inohana 1-8-1, Chuo-ku, Chiba, Japan
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32
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Cebecauerova D, Jirasek T, Budisova L, Mandys V, Volf V, Novotna Z, Subhanova I, Hrebicek M, Elleder M, Jirsa M. Dual hereditary jaundice: simultaneous occurrence of mutations causing Gilbert's and Dubin-Johnson syndrome. Gastroenterology 2005; 129:315-20. [PMID: 16012956 DOI: 10.1053/j.gastro.2004.10.009] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
BACKGROUND & AIMS Dubin-Johnson syndrome is recessively inherited, conjugated hyperbilirubinemia induced by mutations in the ABCC2/MRP2 gene encoding the canalicular transporter for conjugated bilirubin. Gilbert's syndrome is recessively inherited, unconjugated hyperbilirubinemia caused by decreased conjugation rate of bilirubin associated mostly with homozygous A(TA) 7 TAA variant of the TATAA-box in the UGT1A1 gene promoter. Our aim was to establish the molecular diagnosis in a 3-year-old male with atypical, intermittent, predominantly unconjugated, hyperbilirubinemia. METHODS 99m Tc-HIDA cholescintigraphy was used for imaging the biliary tree. Expression of ABCC2/MRP2 protein in hepatocytes was investigated immunohistochemically. UGT1A1 and ABCC2/MRP2 genes were sequenced from genomic DNA, and the mutations were verified by fragment analysis, sequencing the cloned exons, and restriction fragment length polymorphism. RESULTS Cholescintigraphy revealed delayed visualization of the gallbladder. A brown granular lipopigment differing from melanin-like pigment reported in Dubin-Johnson syndrome was present in hepatocytes, but, otherwise, liver histology was normal. ABCC2/MRP2 protein was not detected on the canalicular membrane of hepatocytes, and 2 novel mutations were found in the ABCC2/MRP2 gene: a heterozygous in-frame insertion-deletion mutation 1256insCT/delAAACAGTGAACCTGATG in exon 10 inherited from the father and a heterozygous deletion 4292delCA in exon 30 inherited from the mother. In addition, the patient was homozygous for -3279T>G and A(TA) 7 TAA mutations in the UGT1A1 gene promoter. CONCLUSIONS Our patient represents a case of digenic mixed hyperbilirubinemia-a distinct type of constitutive jaundice resulting from coinherited defects in ABCC2/MRP2 and UGT1A1 genes.
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Affiliation(s)
- Dita Cebecauerova
- Institute for Clinical and Experimental Medicine, Prague, Czech Republic
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33
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Abstract
The Na exchanger regulatory factor (NHERF) family of epithelial-enriched PDZ domain scaffolding proteins plays important roles in maintaining and regulating epithelial cell function. The NHERFs exhibit some overlap in tissue distribution and binding partners, suggesting redundant functions. Yet, it is clear that each NHERF protein exhibits distinct properties, translating into unique cellular functions. The work summarized in this review suggests the most recently identified family member, NHERF4, is the most divergent. Additional investigation is needed, however, to understand more completely the role of NHERF4 in the context of the NHERF family.
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Affiliation(s)
- William R Thelin
- Department of Cell and Developmental Biology, The University of North Carolina at Chapel Hill, CB 7090, Chapel Hill, NC 27599, USA
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34
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Ritter CA, Jedlitschky G, Meyer zu Schwabedissen H, Grube M, Köck K, Kroemer HK. Cellular export of drugs and signaling molecules by the ATP-binding cassette transporters MRP4 (ABCC4) and MRP5 (ABCC5). Drug Metab Rev 2005; 37:253-78. [PMID: 15747503 DOI: 10.1081/dmr-200047984] [Citation(s) in RCA: 110] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Like other members of the multidrug resistance protein (MRP)/ABCC subfamily of ATP-binding cassette transporters, MRP4 (ABCC4) and MRP5 (ABCC5) are organic anion transporters. They have, however, the outstanding ability to transport nucleotides and nucleotide analogs. In vitro experiments using drug-selected or -transfected cells indicated that these transport proteins, when overexpressed, can lower the intracellular concentration of nucleoside/nucleotide analogs, such as the antiviral compounds PMEA (9-(2-phosphonylmethoxyethyl)adenine) or ganciclovir, and of anticancer nucleobase analogs, such as 6-mercaptopurine, after their conversion into the respective nucleotides. This may lead to an impaired ability of these compounds to inhibit virus replication or cell proliferation. It remains to be tested whether antiviral or anticancer chemotherapy based on nucleobase, nucleoside, or nucleotide precursors can be modulated by inhibition of MRP4 and MRP5. MRP4 also seems to be able to mediate the transport of conjugated steroids, prostaglandins, and glutathione. Furthermore, cyclic nucleotides (cyclic adenosine monophosphate and cyclic guanine monophosphate) are exported from cells by MRP4 and MRP5. This may modulate the intracellular concentration of these important mediators, besides the action of phosphodiesterases, as well as provide extracellular nucleotides for a possible paracrine action. In this line, tissue distribution and subcellular localization of MRP4 and MRP5 specifically in smooth muscle cells (MRP5), platelet-dense granules (MRP4), and nervous cells (MRP4 and MRP5), besides the capillary endothelium, point not only to a possible function of these transporters as exporters in cellular defense, but also to a physiological function in signaling processes.
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Affiliation(s)
- Christoph A Ritter
- Department of Pharmacology, Peter Holtz Research Center of Pharmacology and Experimental Therapeutics, Ernst-Moritz-Arndt University Greifswald, Greifswald, Germany
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35
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Batrakova EV, Li S, Li Y, Alakhov VY, Kabanov AV. Effect of pluronic P85 on ATPase activity of drug efflux transporters. Pharm Res 2005; 21:2226-33. [PMID: 15648254 PMCID: PMC2677181 DOI: 10.1007/s11095-004-7675-5] [Citation(s) in RCA: 117] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
PURPOSE Pluronic block copolymers are potent sensitizers of multi-drug resistant (MDR) cancer cells. The sensitization effect by Pluronics is a result of two processes acting in concert: i) intracellular ATP depletion, and ii) inhibition of ATPase activity of drug efflux proteins. This work characterizes effects of Pluronic P85 on ATPase activities of Pgp, MRP1, and MRP2 drug efflux transport proteins and interaction of these proteins with their substrates, vinblastine, and leucotriene C4. METHODS Using membranes overexpressing Pgp, MRP1, and MRP2, the current study evaluates effects of Pluronic P85 (P85) on the kinetic parameters (Vmax, Km, Vmax/Km) of ATP hydrolysis by these ATPases. RESULTS The decreases in the maximal reaction rates (Vmax) and increases in apparent Michaelis constants (Km) for these transporters in the presence of various concentrations of P85 were observed. The mechanism of these effects may involve i) conformational changes of the transporter due to membrane fluidization and/or ii) nonspecific steric hindrance of the drug-binding sites by P85 chains embedded into cellular membranes. The extent of these alterations was increased in the row MRP1 < MRP2 << Pgp. CONCLUSIONS These data suggest that there are unifying pathways for the inhibition of Pgp and MRPs by the block copolymer. However, the effect of P85 on Pgp ATPase activity is considerably greater compared with the effects on MRP1 and MRP2 ATPases. This may be a reason for greater inhibitory effects of Pluronic in Pgp- compared with MRP-overexpressing cells.
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Affiliation(s)
- Elena V. Batrakova
- Department of Pharmaceutical Sciences, University of Nebraska Medical Center, 985830 Nebraska Medical Center, Omaha, Nebraska 68198-5830, USA
| | - Shu Li
- Department of Pharmaceutical Sciences, University of Nebraska Medical Center, 985830 Nebraska Medical Center, Omaha, Nebraska 68198-5830, USA
| | - Yili Li
- Department of Pharmaceutical Sciences, University of Nebraska Medical Center, 985830 Nebraska Medical Center, Omaha, Nebraska 68198-5830, USA
| | - Valery Yu. Alakhov
- Supratek Pharma Inc., 215, boulevard Bouchard #1315, Dorval, Quebec, Canada H9S 1A9
| | - Alexander V. Kabanov
- Department of Pharmaceutical Sciences, University of Nebraska Medical Center, 985830 Nebraska Medical Center, Omaha, Nebraska 68198-5830, USA
- To whom correspondence should be addressed. (e-mail: )
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36
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Deters M, Kirchner G, Koal T, Resch K, Kaever V. Influence of Cyclosporine on the Serum Concentration and Biliary Excretion of Mycophenolic Acid and 7-O-Mycophenolic Acid Glucuronide. Ther Drug Monit 2005; 27:132-8. [PMID: 15795641 DOI: 10.1097/01.ftd.0000152682.13647.5e] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The authors have investigated whether cyclosporine decreases the serum concentration of mycophenolic acid, the active principle of the immunosuppressant mycophenolate mofetil, and increases that of the inactive metabolite 7-O-mycophenolic acid glucuronide by reducing their enterohepatic recirculation. Rats were treated daily with methylcellulose (1.66 mL/kg PO) plus 0.9% NaCl (6 mL/kg IP), mycophenolate mofetil (20 mg/kg PO) plus 0.9% NaCl (6 mL/kg IP), methylcellulose (1.66 mL/kg PO) plus cyclosporine (5 mg/kg IP), and mycophenolate mofetil (20 mg/kg PO) plus cyclosporine (5 mg/kg IP). After 14 days a bile fistula was installed to measure the biliary excretion of the immunosuppressants and their metabolites. After 90 minutes blood was taken to determine their concentrations in blood or serum by HPLC. Cyclosporine significantly decreased the serum concentration of mycophenolic acid by 39% and increased, not significantly, that of 7-O-mycophenolic acid glucuronide by 53%. The biliary excretion of 7-O-mycophenolic acid glucuronide was significantly reduced by cyclosporine by 57%, whereas that of mycophenolic acid was not affected. Mycophenolate mofetil did not show a significant effect on either the blood concentration or the biliary excretion of cyclosporine and its metabolites AM1, AM9, AM1c, and AM4N. Cyclosporine significantly decreased the serum concentration of active mycophenolate acid and increased, not significantly, the serum concentration of inactive 7-O-mycophenolic acid glucuronide, presumably by reducing the biliary excretion of this inactive metabolite.
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Affiliation(s)
- Michael Deters
- Institute of Pharmacology, Medical School Hannover, 30623 Hannover, Germany.
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37
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Fardel O, Jigorel E, Le Vee M, Payen L. Physiological, pharmacological and clinical features of the multidrug resistance protein 2. Biomed Pharmacother 2005; 59:104-14. [PMID: 15795103 DOI: 10.1016/j.biopha.2005.01.005] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2004] [Indexed: 12/17/2022] Open
Abstract
Multidrug resistance protein 2 (MRP2, ABCC2) is a drug efflux pump belonging to the ATP-binding cassette (ABC) transporter superfamily. MRP2 is present predominantly at the biliary pole of hepatocytes and is also expressed in the kidney and intestine. It plays a major role in hepato-biliary elimination of many structurally diverse xenobiotics, including organic anions and drug conjugates, and therefore most likely contributes to pharmacokinetic parameters of these compounds. MRP2 also handles endogenous molecules such as bilirubin, and its overexpression has been shown to confer a multidrug resistance phenotype to tumoral cells. MRP2 expression can be regulated by endogenous substances such as inflammatory cytokines and biliary acids. The MRP2 levels and activity can also be affected by a large panel of xenobiotics, including chemopreventive agents and ligands of the pregnane X receptor, which may be a potential source of drug-drug interactions and drug adverse effects. MRP2 appears therefore as one of the major drug efflux pumps of the organism, whose functional and regulatory features are important to consider, notably for drug disposition.
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Affiliation(s)
- Olivier Fardel
- Inserm U620, Faculté de Pharmacie, 2 Avenue Professeur Leon Bernard, 35043 Rennes, France.
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38
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Westlake CJ, Cole SPC, Deeley RG. Role of the NH2-terminal membrane spanning domain of multidrug resistance protein 1/ABCC1 in protein processing and trafficking. Mol Biol Cell 2005; 16:2483-92. [PMID: 15772158 PMCID: PMC1087251 DOI: 10.1091/mbc.e04-12-1113] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Multidrug resistance protein (MRP)1/ABCC1 transports organic anionic conjugates and confers resistance to cytotoxic xenobiotics. In addition to two membrane spanning domains (MSDs) typical of most ATP-binding cassette (ABC) transporters, MRP1 has a third MSD (MSD0) of unknown function. Unlike some topologically similar ABCC proteins, removal of MSD0 has minimal effect on function, nor does it prevent MRP1 from trafficking to basolateral membranes in polarized cells. However, we find that independent of cell type, the truncated protein accumulates in early/recycling endosomes. Using a real-time internalization assay, we demonstrate that MSD0 is important for MRP1 retention in, or recycling to, the plasma membrane. We also show that MSD0 traffics independently to the cell surface and promotes membrane localization of the core-region of MRP1 when the two protein fragments are coexpressed. Finally, we demonstrate that MSD0 becomes essential for trafficking of MRP1 when the COOH-terminal region of the protein is mutated. These studies demonstrate that MSD0 and the COOH-terminal region contain redundant trafficking signals, which only become essential when one or the other region is missing or is mutated. These data explain apparent differences in the trafficking requirement for MSD0 and the COOH-terminal region of MRP1 compared with other ABCC proteins.
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39
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Torky ARW, Stehfest E, Viehweger K, Taege C, Foth H. Immuno-histochemical detection of MRPs in human lung cells in culture. Toxicology 2005; 207:437-50. [PMID: 15664271 DOI: 10.1016/j.tox.2004.10.014] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2004] [Revised: 10/24/2004] [Accepted: 10/27/2004] [Indexed: 10/26/2022]
Abstract
The transport of molecules across membranes is an essential function of all living organisms and a large number of specific transporters have evolved to carry out this function. The largest transporter gene family is the ATP-binding cassette (ABC) transporter superfamily. The multidrug resistance-associated protein (MRP) family is comprised of nine related ABC transporters. The intra-cellular distribution of the different MRP isoforms in relation to their physiological and non physiological function is still a point of discussion. For this purpose we used normal human lung cells (bronchial epithelial cells, NHBEC, and peripheral lung cells, PLC) as well as tumor cell cultures as test tools to investigate the intracelluar localization of these proteins under classical culture conditions and under air-liquid interface by means of indirect fluorescence microscopy. Characterization of the cultured cells as lung epithelial cells was performed by means of immuno-histochemical analysis. MRP1 and MRP3 were localised to the cellular membrane in all tested lung cell types. In contrast to that MRP2, MRP4 and MRP5 could be described as intracellular proteins in NHBEC and PLC. All MRP1-MRP5 isoforms could be characterized in A549 tumor cell line as membrane proteins. In order to imitate the physiological in vivo circumstances in the lung, we have established a dry/wet method (air-liquid interface) for cell cultivation so that cultured cells have the option to polarize between air and basal membrane and this might influence the distribution pattern of MRP1 and MRP2 in NHBEC. Using confocal laser scanning techniques we could show that in cells kept under dry/wet conditions MRP1 was found to be localised to baso-lateral cell regions while MRP2 was localised to all cell regions. Under classical culture conditions MRP1 was not localized to particular membrane regions and MRP2 was found to be an intracellular protein.
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40
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Westlake CJ, Payen L, Gao M, Cole SPC, Deeley RG. Identification and characterization of functionally important elements in the multidrug resistance protein 1 COOH-terminal region. J Biol Chem 2004; 279:53571-83. [PMID: 15459206 DOI: 10.1074/jbc.m402528200] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The ATP binding cassette (ABC) transporter, multidrug resistance protein 1 (MRP1/ABCC1), transports a broad spectrum of conjugated and unconjugated compounds, including natural product chemotherapeutic agents. In this study, we have investigated the importance of the COOH-terminal region of MRP1 for transport activity and basolateral plasma membrane trafficking. The COOH-terminal regions of some ABCC proteins have been implicated in protein trafficking, but the function of this region of MRP1 has not been defined. In contrast to results obtained with other ABCC proteins, we found that the COOH-proximal 30 amino acids of MRP1 can be removed without affecting trafficking to basolateral membranes. However, the truncated protein is inactive. Furthermore, removal of as few as 4 COOH-terminal amino acids profoundly decreases transport activity. Although amino acid sequence conservation of the COOH-terminal regions of ABC proteins is low, secondary structure predictions indicate that they consist of a broadly conserved helix-sheet-sheet-helix-helix structure. Consistent with a conservation of secondary and tertiary structure, MRP1 hybrids containing the COOH-terminal regions of either the homologous MRP2 or the distantly related P-glycoprotein were fully active and trafficked normally. Using mutated proteins, we have identified structural elements containing five conserved hydrophobic amino acids that are required for activity. We show that these are important for binding and hydrolysis of ATP by nucleotide binding domain 2. Based on crystal structures of several ABC proteins, we suggest that the conserved amino acids may stabilize a helical bundle formed by the COOH-terminal three helices and may contribute to interactions between the COOH-terminal region and the protein's two nucleotide binding domains.
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41
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Hernando N, Wagner CA, Gisler SM, Biber J, Murer H. PDZ proteins and proximal ion transport. Curr Opin Nephrol Hypertens 2004; 13:569-74. [PMID: 15300165 DOI: 10.1097/00041552-200409000-00014] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE OF REVIEW PDZ proteins are major structural components of protein assembly. This review covers the implications of these proteins in the regulation of transport systems expressed in renal proximal tubules. RECENT FINDINGS In the last few years, many reports have highlighted the implication of PDZ proteins in two aspects of proximal tubule physiology, namely the generation and maintenance of epithelial polarity and the formation of regulatory complexes that provide spatial and molecular specificity to the intracellular signalling. SUMMARY PDZ-mediated interactions are involved in a wide range of cellular functions, from cell division to cell polarity to intracellular signalling. Consistent with this functional spectrum, ablation of PDZ protein genes generates a wide panel of pathological phenotypes, some of which link directly to human syndromes. In proximal tubules, PDZ proteins are thought to play a major role in epithelial polarity and transport regulation.
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Affiliation(s)
- Nati Hernando
- Institute of Physiology, Zurich University, CH-8057 Zurich, Switzerland.
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42
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Murphy SJ, Doré JJE, Edens M, Coffey RJ, Barnard JA, Mitchell H, Wilkes M, Leof EB. Differential trafficking of transforming growth factor-beta receptors and ligand in polarized epithelial cells. Mol Biol Cell 2004; 15:2853-62. [PMID: 15075369 PMCID: PMC420108 DOI: 10.1091/mbc.e04-02-0097] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Epithelial cells in vivo form tight cell-cell associations that spatially separate distinct apical and basolateral domains. These domains provide discrete cellular processes essential for proper tissue and organ development. Using confocal imaging and selective plasma membrane domain activation, the type I and type II transforming growth factor-beta (TGFbeta) receptors were found to be localized specifically at the basolateral surfaces of polarized Madin-Darby canine kidney (MDCK) cells. Receptors concentrated predominantly at the lateral sites of cell-cell contact, adjacent to the gap junctional complex. Cytoplasmic domain truncations for each receptor resulted in the loss of specific lateral domain targeting and dispersion to both the apical and basal domains. Whereas receptors concentrate basolaterally in regions of direct cell-cell contact in nonpolarized MDCK cell monolayers, receptor staining was absent from areas of noncell contact. In contrast to the defined basolateral polarity observed for the TGFbeta receptor complex, TGFbeta ligand secretion was found to be from the apical surfaces. Confocal imaging of MDCK cells with an antibody to TGFbeta1 confirmed a predominant apical localization, with a stark absence at the basal membrane. These findings indicate that cell adhesion regulates the localization of TGFbeta receptors in polarized epithelial cultures and that the response to TGFbeta is dependent upon the spatial distribution and secretion of TGFbeta receptors and ligand, respectively.
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Affiliation(s)
- S J Murphy
- Thoracic Diseases Research Unit, Department of Biochemistry and Molecular Biology and Mayo Clinic Cancer Center, Mayo Clinic College of Medicine, Rochester, Minnesota 55905, USA
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43
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Mizuarai S, Aozasa N, Kotani H. Single nucleotide polymorphisms result in impaired membrane localization and reduced atpase activity in multidrug transporter ABCG2. Int J Cancer 2004; 109:238-46. [PMID: 14750175 DOI: 10.1002/ijc.11669] [Citation(s) in RCA: 233] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
ABCG2/MXR/ABCP1/BCRP is a member of the ATP-binding cassette membrane transporter, which consists of six transmembrane regions and one ATP-binding cassette. The transporter is known to be involved in the efflux of various anticancer compounds such as mitoxantrone, doxorubicin and topoisomerase I inhibitor. In this study, we analyzed the effects of polymorphisms in ABCG2, V12M and Q141K on transporter function. When polarized LLC-PK1 cells were transfected with variant ABCG2, drug-resistance to topoisomerase I inhibitor of cells expressing V12M or Q141K was less than 1/10 that of wild-type ABCG2 transfected cells, and was accompanied by increased drug accumulation and decreased drug efflux in the variant ABCG2-expressing cells. We further elucidated the molecular mechanisms of the transport dysfunction by investigating membrane localization and ATPase activity. Confocal microscopic analysis revealed that apical plasma membrane localization of V12M was disturbed, while the localization of wild-type transporters occurred specifically in the apical plasma membrane of polarized LLC-PK1 cells. Also, ATPase activities measured in the membrane of SF9 cells infected with variant ABCG2 showed that Q141K decreased activity by 1.3 below that of wild-type ABCG2. In addition, kinetic analysis of ATPase activity showed that the K(m) value in Q141K was 1.4-fold higher than that of wild-type ABCG2. These results indicated that naturally occurring SNPs alter transport functions of ABCG2 transporter and analysis of SNPs in ABCG2 may hold great importance in understanding the response/metabolism of chemotherapy compounds that act as substrates for ABCG2.
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MESH Headings
- ATP Binding Cassette Transporter, Subfamily G, Member 2
- ATP-Binding Cassette Transporters/genetics
- ATP-Binding Cassette Transporters/metabolism
- Adenosine Triphosphatases/metabolism
- Adolescent
- Adult
- Aged
- Aged, 80 and over
- Animals
- Biological Transport
- Case-Control Studies
- Cell Membrane/enzymology
- Drug Resistance, Multiple/genetics
- Drug Screening Assays, Antitumor
- Female
- Gene Expression Regulation, Neoplastic
- Gene Frequency
- Humans
- LLC-PK1 Cells
- Male
- Middle Aged
- Neoplasm Proteins/genetics
- Neoplasm Proteins/metabolism
- Polymorphism, Single Nucleotide/physiology
- Protein Transport
- RNA, Messenger/analysis
- RNA, Neoplasm/genetics
- Swine
- Transfection
- Tumor Cells, Cultured
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Affiliation(s)
- Shinji Mizuarai
- Banyu Tsukuba Research Institute in collaboration with Merck Research Laboratories, Tsukuba, Ibaraki, Japan
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44
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Abstract
The MRP family is comprised of nine related ABC transporters that are able to transport structurally diverse lipophilic anions and function as drug efflux pumps. Investigations of this family have provided insights not only into cellular resistance mechanisms associated with natural product chemotherapeutic agents, antifolates and nucleotide analogs, but also into factors that influence drug distribution in the body, membrane systems that are involved in the extrusion of reduced folates, cysteinyl leukotrienes and bile acids, and the molecular basis of two hereditary conditions in humans. The review will describe the biochemical properties, drug resistance activities and potential in vivo functions of these unusual pumps.
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Affiliation(s)
- Gary D Kruh
- Medical Science Division, Fox Chase Cancer Center, Philadelphia, PA 19111, USA.
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45
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Mizuno N, Niwa T, Yotsumoto Y, Sugiyama Y. Impact of drug transporter studies on drug discovery and development. Pharmacol Rev 2003; 55:425-61. [PMID: 12869659 DOI: 10.1124/pr.55.3.1] [Citation(s) in RCA: 398] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Drug transporters are expressed in many tissues such as the intestine, liver, kidney, and brain, and play key roles in drug absorption, distribution, and excretion. The information on the functional characteristics of drug transporters provides important information to allow improvements in drug delivery or drug design by targeting specific transporter proteins. In this article we summarize the significant role played by drug transporters in drug disposition, focusing particularly on their potential use during the drug discovery and development process. The use of transporter function offers the possibility of delivering a drug to the target organ, avoiding distribution to other organs (thereby reducing the chance of toxic side effects), controlling the elimination process, and/or improving oral bioavailability. It is useful to select a lead compound that may or may not interact with transporters, depending on whether such an interaction is desirable. The expression system of transporters is an efficient tool for screening the activity of individual transport processes. The changes in pharmacokinetics due to genetic polymorphisms and drug-drug interactions involving transporters can often have a direct and adverse effect on the therapeutic safety and efficacy of many important drugs. To obtain detailed information about these interindividual differences, the contribution made by transporters to drug absorption, distribution, and excretion needs to be taken into account throughout the drug discovery and development process.
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Affiliation(s)
- Naomi Mizuno
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
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46
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Altschuler Y, Hodson C, Milgram SL. The apical compartment: trafficking pathways, regulators and scaffolding proteins. Curr Opin Cell Biol 2003; 15:423-9. [PMID: 12892782 DOI: 10.1016/s0955-0674(03)00084-x] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Defects in the trafficking of apical membrane proteins in polarized epithelial cells are often associated with diseases, including cystic fibrosis, Liddle's syndrome, nephrogenic diabetes insipidus and Dubin-Johnson syndrome. In recent years, we have learned much about the specialized apical trafficking pathways in polarized cells. Many laboratories have identified signals that direct proteins within these pathways and have defined protein interactions that mediate specific steps in the sorting and stabilization of these proteins. In addition, many cytosolic proteins, including lipid kinases, GTPases, ATPases and scaffolding/adaptor proteins that lack enzymatic activity, regulate the trafficking of proteins through these pathways. Recent advances in the field include the role of small GTPases, unconventional myosins and lipid kinases in apical endocytosis and transcytosis, and the identification of PDZ proteins that regulate apical membrane trafficking of receptors, transporters and ion channels.
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Affiliation(s)
- Yoram Altschuler
- Department of Pharmacology, School of Pharmacy, Faculty of Medicine, Hebrew University of Jerusalem, Ein Kerem Campus, 91120, Jerusalem, Israel.
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47
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Konno T, Ebihara T, Hisaeda K, Uchiumi T, Nakamura T, Shirakusa T, Kuwano M, Wada M. Identification of domains participating in the substrate specificity and subcellular localization of the multidrug resistance proteins MRP1 and MRP2. J Biol Chem 2003; 278:22908-17. [PMID: 12682044 DOI: 10.1074/jbc.m302868200] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The human multidrug resistance protein MRP1 and its homolog, MRP2, are both thought to be involved in cancer drug resistance and the transport of a wide variety of organic anions, including the cysteinyl leukotriene C4 (LTC4) (Km = 0.1 and 1 microm). To determine which domain of these proteins is associated with substrate specificity and subcellular localization, we constructed various chimeric MRP1/MRP2 molecules and expressed them in polarized mammalian LLC-PK1 cells. We examined the kinetic properties of each chimeric protein by measuring LTC4 and methotrexate transport in inside-out membrane vesicles, sensitivity to an anticancer agent, etoposide, and subcellular localization by indirect immunofluorescence methods. The following results were determined in these studies: (i) when the NH2-proximal 108 amino acids of MRP2, including transmembrane (TM) helices 1-3, were exchanged with the corresponding region of MRP1, Km(LTC4) values of the chimera decreased approximately 4-fold and Km(methotrexate) values increased approximately 5-fold relative to those of wild-type MRP2 and MRP1, respectively, whereas resistance to etoposide increased approximately 3-fold; (ii) when the NH2-proximal region up to TM9 of MRP2 was exchanged with the corresponding region of MRP1, a further increase in etoposide resistance was observed, and subcellular localization moved from the apical to the lateral membrane; (iii) when two-thirds of MRP2 at the NH2 terminus were exchanged with the corresponding MRP1 region, the chimeric protein transported LTC4 with an efficiency comparable with that achieved by the wild-type MRP1; and (iv) exchange of the COOH-terminal 51 amino acids between MRP1 and MRP2 did not affect the localization of either of the proteins. These results provide a strong framework for further studies aimed at determining the precise domains of MRP1 and MRP2 with affinity for LTC4 and anticancer agents.
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Affiliation(s)
- Toshikazu Konno
- Department of Medical Biochemistry, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
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48
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Hegedüs T, Sessler T, Scott R, Thelin W, Bakos E, Váradi A, Szabó K, Homolya L, Milgram SL, Sarkadi B. C-terminal phosphorylation of MRP2 modulates its interaction with PDZ proteins. Biochem Biophys Res Commun 2003; 302:454-61. [PMID: 12615054 DOI: 10.1016/s0006-291x(03)00196-7] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
MRP2, a member of the ABC protein superfamily, functions as an ATP-dependent export pump for anionic conjugates in the apical membranes of epithelial cells. It has been reported that the trafficking of MRP2 is modulated by PKC. Adjacent to the C-terminal PDZ binding motif, which may be involved in the targeting of MRP2, we found a potential PKC phosphorylation site (Ser(1542)). Therefore, we examined the interaction of MRP2 and its phosphorylation-mimicking mutants with different PDZ proteins (EBP50, E3KARP, PDZK1, IKEPP, beta2-syntrophin, and SAP-97). The binding of these PDZ proteins to CFTR and ABCA1, other ABC proteins, possessing PDZ binding motif, was also studied. We observed a strong binding of apically localized PDZ proteins to both MRP2 and CFTR, whereas beta2-syntrophin exhibited binding only to ABCA1. The phosphorylation-mimicking MRP2 mutant and a phosphorylated C-terminal MRP2 peptide showed significantly increased binding to IKEPP, EBP50, and both individual PDZ domains of EBP50. Our results suggest that phosphorylation of the MRP2 PDZ binding motif has a profound effect on the PDZ binding of MRP2.
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Affiliation(s)
- Tamás Hegedüs
- Department of Molecular Cell Biology, Membrane Research Group of the Hungarian Academy of Sciences, National Medical Center, Diószegi u. 64, 1113 Budapest, Hungary
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49
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Keitel V, Nies AT, Brom M, Hummel-Eisenbeiss J, Spring H, Keppler D. A common Dubin-Johnson syndrome mutation impairs protein maturation and transport activity of MRP2 (ABCC2). Am J Physiol Gastrointest Liver Physiol 2003; 284:G165-74. [PMID: 12388192 DOI: 10.1152/ajpgi.00362.2002] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Absence of a functional multidrug resistance protein 2 (MRP2; symbol ABCC2) from the hepatocyte canalicular membrane is the molecular basis of Dubin- Johnson syndrome, an inherited disorder associated with conjugated hyperbilirubinemia in humans. In this work, we analyzed a relatively frequent Dubin-Johnson syndrome mutation that leads to an exchange of two hydrophobic amino acids, isoleucine 1173 to phenylalanine (MRP2I1173F), in a predicted extracellular loop of MRP2. HEK-293 cells stably transfected with MRP2I1173F cDNA synthesized a mutant protein that was mainly core-glycosylated, predominantly retained in the endoplasmic reticulum, and degraded by proteasomes. MRP2I1173F did not mediate ATP-dependent transport of leukotriene C(4) (LTC(4)) into vesicles from plasma membrane and endoplasmic reticulum preparations while normal MRP2 was functionally active. Human HepG2 cells were used to study localization of MRP2I1173F in a polarized cell system. Quantitative analysis showed that GFP-tagged MRP2I1173F was localized to the apical membrane in only 5% of transfected, polarized HepG2 cells compared with 80% for normal MRP2-GFP. Impaired protein maturation followed by proteasomal degradation of inactive MRP2I1173F explain the deficient hepatobiliary elimination observed in this group of Dubin-Johnson syndrome patients.
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Affiliation(s)
- Verena Keitel
- Division of Tumor Biochemistry, Deutsches Krebsforschungszentrum, D-69120 Heidelberg, Germany
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50
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Adachi M, Reid G, Schuetz JD. Therapeutic and biological importance of getting nucleotides out of cells: a case for the ABC transporters, MRP4 and 5. Adv Drug Deliv Rev 2002; 54:1333-42. [PMID: 12406648 DOI: 10.1016/s0169-409x(02)00166-7] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The energy dependent transport of drugs contributes to cellular resistance and is undoubtedly a prime suspect in chemotherapeutic failure of a variety of disease processes. Early studies focused on a single gene, the multidrug resistance gene, MDR1, as a main contributor to chemotherapeutic failure. However, the multifaceted nature of cellular resistance lead to the discovery of the MRP gene. This pivotal finding and the concurrent rapid development of gene databases lead to the expansion of the MRP gene family. The purpose of this review is to discuss two of the recently described MRP family members that were orphans until their role in drug resistance was discovered. This review will provide an overview of the current state of our understanding of MRP4 and 5.
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Affiliation(s)
- Masashi Adachi
- Department of Pharmaceutical Sciences, St Jude Children's Research Hospital, 332 N Lauderdale Avenue, Memphis, TN 38105, USA
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