scholarly journals Multidrug-resistance protein 5 is a multispecific organic anion transporter able to transport nucleotide analogs

2000 ◽  
Vol 97 (13) ◽  
pp. 7476-7481 ◽  
Author(s):  
J. Wijnholds ◽  
C. A. A. M. Mol ◽  
L. van Deemter ◽  
M. de Haas ◽  
G. L. Scheffer ◽  
...  
Keyword(s):  
Multidrug Resistance ◽  
Organic Anion ◽  
Organic Anion Transporter ◽  
Multidrug Resistance Protein ◽  
Nucleotide Analogs ◽  
Anion Transporter ◽  
Resistance Protein

scholarly journals ATP-dependent transport of bilirubin glucuronides by the multidrug resistance protein MRP1 and its hepatocyte canalicular isoform MRP2

1997 ◽  
Vol 327 (1) ◽  
pp. 305-310 ◽  
Author(s):  
Gabriele JEDLITSCHKY ◽  
Inka LEIER ◽  
Ulrike BUCHHOLZ ◽  
Johanna HUMMEL-EISENBEISS ◽  
Brian BURCHELL ◽  
...  
Keyword(s):  
Multidrug Resistance ◽  
Membrane Vesicle ◽  
Organic Anion ◽  
Membrane Vesicles ◽  
Organic Anion Transporter ◽  
Multidrug Resistance Protein ◽  
Leukotriene C4 ◽  
Anion Transporter ◽  
Resistance Protein ◽  
Dependent Transport

Bilirubin is secreted from the liver into bile mainly as monoglucuronosyl and bisglucuronosyl conjugates. We demonstrate for the first time that ATP-dependent transport of both bilirubin glucuronides is mediated by the multidrug resistance protein (MRP1) as well as by the distinct canalicular (apical) isoform MRP2, also termed cMRP or cMOAT (canalicular multispecific organic anion transporter). In membrane vesicles from MRP1-transfected HeLa cells mono[3H]glucuronosylbilirubin and bis[3H]glucuronosylbilirubin (each at 0.5 μM) were transported with rates of 5.3 and 3.1 pmol/min per mg of protein respectively. Rat hepatocyte canalicular membrane vesicles, which contain Mrp2 (the rat equivalent of MRP2), transported mono[3H]glucuronosylbilirubin and bis[3H]glucuronosylbilirubin at rates of 8.9 and 8.5 pmol/min per mg of protein, whereas membrane vesicles from mutant liver lacking Mrp2 showed no transport of the conjugates. In membrane vesicles from human hepatoma Hep G2 cells, which predominantly expressed MRP2, transport rates were 8.3 and 4.4 pmol/min per mg of protein for monoglucuronosylbilirubin and bisglucuronosylbilirubin respectively. ATP-dependent transport of the glutathione S-conjugate [3H]leukotriene C4, an established high-affinity substrate for MRP1 and MRP2, was inhibited by both bilirubin glucuronides with IC50 values between 0.10 and 0.75 μM. The ratios of leukotriene C4 transport and bilirubin glucuronide transport, determined in the same membrane vesicle preparation, indicated substrate specificity differences between MRP1 and MRP2 with a preference of MRP2 for the glucuronides.

scholarly journals Canalicular multispecific organic anion transporter/multidrug resistance protein 2 mediates low-affinity transport of reduced glutathione

1999 ◽  
Vol 338 (2) ◽  
pp. 393-401 ◽  
Author(s):  
Coen C. PAULUSMA ◽  
Michael A. van GEER ◽  
Raymond EVERS ◽  
Marc HEIJN ◽  
Roelof OTTENHOFF ◽  
...  
Keyword(s):  
Multidrug Resistance ◽  
Bile Flow ◽  
Organic Anion ◽  
Fold Increase ◽  
Organic Anion Transporter ◽  
Multidrug Resistance Protein ◽  
Wild Type ◽  
Anion Transporter ◽  
Mdckii Cells ◽  
Resistance Protein

The canalicular multispecific organic anion transporter (cMOAT), a member of the ATP-binding cassette transporter family, mediates the transport of a broad range of non-bile salt organic anions from liver into bile. cMOAT-deficient Wistar rats (TR-) are mutated in the gene encoding cMOAT, leading to defective hepatobiliary transport of a whole range of substrates, including bilirubin glucuronide. These mutants also have impaired hepatobiliary excretion of GSH and, as a result, the bile flow in these animals is reduced. In the present work we demonstrate a role for cMOAT in the excretion of GSH both in vivo and in vitro. Biliary GSH excretion in rats heterozygous for the cMOAT mutation (TR/tr) was decreased to 63% of controls (TR/TR) (114±24 versus 181±20 nmol/min per kg body weight). Madin-Darby canine kidney (MDCK) II cells stably expressing the human cMOAT protein displayed > 10-fold increase in apical GSH excretion compared with wild-type MDCKII cells (141±6.1 pmol/min per mg of protein versus 13.2±1.3 pmol/min per mg of protein in wild-type MDCKII cells). Similarly, MDCKII cells expressing the human multidrug resistance protein 1 showed a 4-fold increase in GSH excretion across the basolateral membrane. In several independent cMOAT-transfectants, the level of GSH excretion correlated with the expression level of the protein. Furthermore, we have shown, in cMOAT-transfected cells, that GSH is a low-affinity substrate for the transporter and that its excretion is reduced upon ATP depletion. In membrane vesicles isolated from cMOAT-expressing MDCKII cells, ATP-dependent S-(2,4-dinitrophenyl)glutathione uptake is competitively inhibited by high concentrations of GSH (Ki≈ 20 mM). We concluded that cMOAT mediates low-affinity transport of GSH. However, since hepatocellular GSH concentrations are high (5–10 mM), cMOAT might serve an important physiological function in maintenance of bile flow in addition to hepatic GSH turnover.

scholarly journals Cyclic AMP stimulates sorting of the canalicular organic anion transporter (Mrp2/cMoat) to the apical domain in hepatocyte couplets

1998 ◽  
Vol 111 (8) ◽  
pp. 1137-1145 ◽  
Author(s):  
H. Roelofsen ◽  
C.J. Soroka ◽  
D. Keppler ◽  
J.L. Boyer
Keyword(s):  
Apical Membrane ◽  
Organic Anion ◽  
Anion Transport ◽  
Transport Protein ◽  
Organic Anion Transporter ◽  
Multidrug Resistance Protein ◽  
Multidrug Resistance Protein 2 ◽  
Apical Domain ◽  
Anion Transporter ◽  
Resistance Protein

The canalicular membrane of rat hepatocytes contains an ATP-dependent multispecific organic anion transporter, also named multidrug resistance protein 2, that is responsible for the biliary secretion of several amphiphilic organic anions. This transport function is markedly diminished in mutant rats that lack the transport protein. To assess the role of vesicle traffic in the regulation of canalicular organic anion transport, we have examined the redistribution of the transporter to the canalicular membrane and the effect of cAMP on this process in isolated hepatocyte couplets, which retain secretory polarity. The partial disruption of cell-cell contact, due to the isolation procedure, leaves the couplet with both remnant apical membranes, as a source of apical proteins, and an intact apical domain and lumen, to which these proteins are targeted. The changes in distribution of the transporter were correlated to the apical excretion of a fluorescent substrate, glutathione-methylfluorescein. The data obtained in this study show that the transport protein, endocytosed from apical membrane remnants, first is redistributed along the basolateral plasma membrane. Then it is transcytosed to the remaining apical pole in a microtubule-dependent fashion, followed by the fusion of transporter-containing vesicles with the apical membrane. The cAMP analog dibutyrylcAMP stimulates all three steps, resulting in increased apically located transport protein, glutathione-methylfluorescein transport activity and apical membrane circumference. These findings indicate that the organic anion transport capacity of the apical membrane in hepatocyte couplets is regulated by cAMP-stimulated sorting of the multidrug resistance protein 2 to the apical membrane. The relevance of this phenomenon for the intact liver is discussed.

scholarly journals Human organic anion transporter 2 is distinct from organic anion transporters 1 and 3 with respect to transport function

2015 ◽  
Vol 309 (10) ◽  
pp. F843-F851 ◽  
Author(s):  
Maja Henjakovic ◽  
Yohannes Hagos ◽  
Wolfgang Krick ◽  
Gerhard Burckhardt ◽  
Birgitta C. Burckhardt
Keyword(s):  
Organic Anion ◽  
Organic Anion Transporter ◽  
Substrate Uptake ◽  
Organic Anion Transporters ◽  
Counter Anion ◽  
Anion Transporters ◽  
Anion Transporter ◽  
293 Cells ◽  
High K ◽  
Resistance Protein

Phylogentically, organic anion transporter (OAT)1 and OAT3 are closely related, whereas OAT2 is more distant. Experiments with human embryonic kidney-293 cells stably transfected with human OAT1, OAT2, or OAT3 were performed to compare selected transport properties. Common to OAT1, OAT2, and OAT3 is their ability to transport cGMP. OAT2 interacted with prostaglandins, and cGMP uptake was inhibited by PGE2 and PGF2α with IC50 values of 40.8 and 12.7 μM, respectively. OAT1 (IC50: 23.7 μM), OAT2 (IC50: 9.5 μM), and OAT3 (IC50: 1.6 μM) were potently inhibited by MK571, an established multidrug resistance protein inhibitor. OAT2-mediated cGMP uptake was not inhibited by short-chain monocarboxylates and, as opposed to OAT1 and OAT3, not by dicarboxylates. Consequently, OAT2 showed no cGMP/glutarate exchange. OAT1 and OAT3 exhibited a pH and a Cl− dependence with higher substrate uptake at acidic pH and lower substrate uptake in the absence of Cl−, respectively. Such pH and Cl− dependencies were not observed with OAT2. Depolarization of membrane potential by high K+ concentrations in the presence of the K+ ionophore valinomycin left cGMP uptake unaffected. In addition to cGMP, OAT2 transported urate and glutamate, but cGMP/glutamate exchange could not be demonstrated. These experiments suggest that OAT2-mediated cGMP uptake does not occur via exchange with monocarboxylates, dicarboxylates, and hydroxyl ions. The counter anion for electroneutral cGMP uptake remains to be identified.

Interaction of immunosuppressive drugs with human organic anion transporter (OAT) 1 and OAT3, and multidrug resistance-associated protein (MRP) 2 and MRP4

2013 ◽  
Vol 162 (6) ◽  
pp. 398-409 ◽  
Author(s):  
Azza A.K. El-Sheikh ◽  
Rick Greupink ◽  
Heleen M. Wortelboer ◽  
Jeroen J.M.W. van den Heuvel ◽  
Marieke Schreurs ◽  
...  
Keyword(s):  
Multidrug Resistance ◽  
Organic Anion ◽  
Immunosuppressive Drugs ◽  
Organic Anion Transporter ◽  
Anion Transporter
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