![]() |
|
|
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Graduate Center for Toxicology, University of Kentucky, Lexington, Kentucky
ß-Estradiol 17-(ß-D-glucuronide) (E217G) is a well known cholestatic agent and substrate of multidrug resistance-associated protein 2 (Mrp2), whereas ß-estradiol 3-(ß-D-glucuronide) (E23G) is a noncholestatic regioisomer of E217G with unknown transport properties. The purpose of this study was to compare and contrast the Mrp2-mediated transport of E217G and E23G. The full coding region of rat Mrp2 was cloned into the baculovirus genome, the recombinant baculovirus used to infect Sf9 cells, and ATP-dependent transport of 3H-E23G and 3H-E217G in Sf9 cell membranes was characterized. Mrp2 transported E23G into an osmotically sensitive space, requiring ATP, with S50 = 55.7 µM, Vmax = 326 pmol·mg-1·min-1, and a Hill coefficient of 0.88. ATP-dependent Mrp2-mediated E217G transport was markedly stimulated at high E217G concentrations, consistent with positive cooperativity (Hill coefficient 1.5). E217G (5-125 µM) increased S50 but not Vmax for E23G transport, consistent with competitive inhibition. E23G (0.4-400 µM) completely, potently (IC50 = 14.2 µM), and competitively inhibited E217G transport, but E217G (0.01-250 µM) inhibited only 53% of E23G transport (IC50 = 33.4 µM). Estriol 16
-(ß-D-glucuronide) potently and completely inhibited transport of E23G (IC50 = 2.23 µM), as did ß-estradiol 3-sulfate 17-(ß-D-glucuronide) (5-50 µM). In summary, E217G binds not only to an Mrp2 transport site, but also to an allosteric site that activates Mrp2 with positive cooperativity, thus activating its own transport and potentially that of other Mrp2 substrates, such as E23G. The noncholestatic E23G is an Mrp2 substrate and competes with E217G for transport, but does not activate the allosteric site.
This article has been cited by other articles:
![]() |
K. Heredi-Szabo, H. Glavinas, E. Kis, D. Mehn, G. Bathori, Z. Veres, L. Kobori, O. von Richter, K. Jemnitz, and P. Krajcsi Multidrug Resistance Protein 2-Mediated Estradiol-17{beta}-D-glucuronide Transport Potentiation: In Vitro-in Vivo Correlation and Species Specificity Drug Metab. Dispos., April 1, 2009; 37(4): 794 - 801. [Abstract] [Full Text] [PDF] |
||||
![]() |
J. S. Lagas, C. M. M. van der Kruijssen, K. van de Wetering, J. H. Beijnen, and A. H. Schinkel Transport of Diclofenac by Breast Cancer Resistance Protein (ABCG2) and Stimulation of Multidrug Resistance Protein 2 (ABCC2)-Mediated Drug Transport by Diclofenac and Benzbromarone Drug Metab. Dispos., January 1, 2009; 37(1): 129 - 136. [Abstract] [Full Text] [PDF] |
||||
![]() |
C. Zimmermann, K. van de Wetering, E. van de Steeg, E. Wagenaar, C. Vens, and A. H. Schinkel Species-Dependent Transport and Modulation Properties of Human and Mouse Multidrug Resistance Protein 2 (MRP2/Mrp2, ABCC2/Abcc2) Drug Metab. Dispos., April 1, 2008; 36(4): 631 - 640. [Abstract] [Full Text] [PDF] |
||||
![]() |
P. M. Gerk, W. Li, V. Megaraj, and M. Vore Human Multidrug Resistance Protein 2 Transports the Therapeutic Bile Salt Tauroursodeoxycholate J. Pharmacol. Exp. Ther., February 1, 2007; 320(2): 893 - 899. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. Ninomiya, K. Ito, R. Hiramatsu, and T. Horie Functional Analysis of Mouse and Monkey Multidrug Resistance-Associated Protein 2 (Mrp2) Drug Metab. Dispos., December 1, 2006; 34(12): 2056 - 2063. [Abstract] [Full Text] [PDF] |
||||
![]() |
P. Jungsuwadee, M. P. Cole, R. Sultana, G. Joshi, J. Tangpong, D. A. Butterfield, D. K. St. Clair, and M. Vore Increase in Mrp1 expression and 4-hydroxy-2-nonenal adduction in heart tissue of Adriamycin-treated C57BL/6 mice. Mol. Cancer Ther., November 1, 2006; 5(11): 2851 - 2860. [Abstract] [Full Text] [PDF] |
||||
![]() |
H. E. Meyer zu Schwabedissen, G. Jedlitschky, M. Gratz, S. Haenisch, K. Linnemann, C. Fusch, I. Cascorbi, and H. K. Kroemer VARIABLE EXPRESSION OF MRP2 (ABCC2) IN HUMAN PLACENTA: INFLUENCE OF GESTATIONAL AGE AND CELLULAR DIFFERENTIATION Drug Metab. Dispos., July 1, 2005; 33(7): 896 - 904. [Abstract] [Full Text] [PDF] |
||||