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Zhou S, Shu Y. Transcriptional Regulation of Solute Carrier (SLC) Drug Transporters. Drug Metab Dispos 2022; 50:DMD-MR-2021-000704. [PMID: 35644529 PMCID: PMC9488976 DOI: 10.1124/dmd.121.000704] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Revised: 05/02/2022] [Accepted: 05/16/2022] [Indexed: 09/03/2023] Open
Abstract
Facilitated transport is necessitated for large size, charged, and/or hydrophilic drugs to move across the membrane. The drug transporters in the solute carrier (SLC) superfamily, mainly including organic anion-transporting polypeptides (OATPs), organic anion transporters (OATs), organic cation transporters (OCTs), organic cation/carnitine transporters (OCTNs), peptide transporters (PEPTs), and multidrug and toxin extrusion proteins (MATEs), are critical facilitators of drug transport and distribution in human body. The expression of these SLC drug transporters is found in tissues throughout the body, with high abundance in the epithelial cells of major organs for drug disposition, such as intestine, liver, and kidney. These SLC drug transporters are clinically important in drug absorption, metabolism, distribution, and excretion. The mechanisms underlying their regulation have been revealing in recent years. Epigenetic and nuclear receptor-mediated transcriptional regulation of SLC drug transporters have particularly attracted much attention. This review focuses on the transcriptional regulation of major SLC drug transporter genes. Revealing the mechanisms underlying the transcription of those critical drug transporters will help us understand pharmacokinetics and pharmacodynamics, ultimately improving drug therapeutic effectiveness while minimizing drug toxicity. Significance Statement It has become increasingly recognized that solute carrier (SLC) drug transporters play a crucial, and sometimes determinative, role in drug disposition and response, which is reflected in decision-making during not only clinical drug therapy but also drug development. Understanding the mechanisms accounting for the transcription of these transporters is critical to interpret their abundance in various tissues under different conditions, which is necessary to clarify the pharmacological response, adverse effects, and drug-drug interactions for clinically used drugs.
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Affiliation(s)
- Shiwei Zhou
- Pharmaceutical Sciences, University of Maryland, United States
| | - Yan Shu
- Pharmaceutical Sciences, University of Maryland, United States
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2
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Giroux P, Kyle PB, Tan C, Edwards JD, Nowicki MJ, Liu H. Evaluating the regulation of transporter proteins and P-glycoprotein in rats with cholestasis and its implication for digoxin clearance. World J Gastrointest Pathophysiol 2022; 13:73-84. [PMID: 35720166 PMCID: PMC9157686 DOI: 10.4291/wjgp.v13.i3.73] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Revised: 10/26/2021] [Accepted: 04/21/2022] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Cardiac and hepatic functionality are intertwined in a multifaceted relationship. Pathologic processes involving one may affect the other through a variety of mechanisms, including hemodynamic and membrane transport effects.
AIM To better understand the effect of extrahepatic cholestasis on regulations of membrane transporters involving digoxin and its implication for digoxin clearance.
METHODS Twelve adult rats were included in this study; baseline hepatic and renal laboratory values and digoxin pharmacokinetic (PK) studies were established before evenly dividing them into two groups to undergo bile duct ligation (BDL) or a sham procedure. After 7 d repeat digoxin PK studies were completed and tissue samples were taken to determine the expressions of cell membrane transport proteins by quantitative western blot and real-time polymerase chain reaction. Data were analyzed using SigmaStat 3.5. Means between pre-surgery and post-surgery in the same experimental group were compared by paired t-test, while independent t-test was employed to compare the means between sham and BDL groups.
RESULTS Digoxin clearance was decreased and liver function, but not renal function, was impaired in BDL rats. BDL resulted in significant up-regulation of multidrug resistance 1 expression in the liver and kidney and its down-regulation in the small intestine. Organic anion transporting polypeptides (OATP)1A4 was up-regulated in the liver but down-regulated in intestine after BDL. OATP4C1 expression was markedly increased in the kidney following BDL.
CONCLUSION The results suggest that cell membrane transporters of digoxin are regulated during extrahepatic cholestasis. These regulations are favorable for increasing digoxin excretion in the kidney and decreasing its absorption from the intestine to compensate for reduced digoxin clearance due to cholestasis.
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Affiliation(s)
- Parker Giroux
- Division of Pediatric Gastroenterology, Department of Pediatrics, University of Mississippi Medical Center, Jackson, MS 39216, United States
| | - Patrick B Kyle
- Department of Pathology, University of Mississippi Medical Center, Jackson, MS 39216, United States
| | - Chalet Tan
- Department of Pharmaceutics and Drug Delivery, University of Mississippi, Oxford, MS 38677, United States
| | - Joseph D Edwards
- Division of Pediatric Gastroenterology, Department of Pediatrics, University of Mississippi Medical Center, Jackson, MS 39216, United States
| | - Michael J Nowicki
- Division of Pediatric Gastroenterology, Department of Pediatrics, University of Mississippi Medical Center, Jackson, MS 39216, United States
| | - Hua Liu
- Division of Pediatric Gastroenterology, Department of Pediatrics, University of Mississippi Medical Center, Jackson, MS 39216, United States
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3
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Donadei C, Angeletti A, Cappuccilli M, Conti M, Conte D, Zappulo F, De Giovanni A, Malvi D, Aldini R, Roda A, La Manna G. Adaptive Mechanisms of Renal Bile Acid Transporters in a Rat Model of Carbon Tetrachloride-Induced Liver Cirrhosis. J Clin Med 2022; 11:jcm11030636. [PMID: 35160088 PMCID: PMC8836491 DOI: 10.3390/jcm11030636] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Revised: 01/19/2022] [Accepted: 01/23/2022] [Indexed: 02/04/2023] Open
Abstract
Background: Acute kidney injury (AKI) is common in advanced liver cirrhosis, a consequence of reduced kidney perfusion due to splanchnic arterial vasodilation and intrarenal vasoconstriction. It clinically manifests as hepatorenal syndrome type 1, type 2, or as acute tubular necrosis. Beyond hemodynamic factors, an additional mechanism may be hypothesized to explain the renal dysfunction during liver cirrhosis. Recent evidence suggest that such mechanisms may be closely related to obstructive jaundice. Methods: Given the not completely elucidated role of bile acids in kidney tissue damage, this study developed a rat model of AKI with liver cirrhosis induction by carbon tetrachloride (CCl4) inhalation for 12 weeks. Histological analyses of renal and liver biopsies were performed at sacrifice. Organic anion tubular transporter distribution and apoptosis in kidney cells were analyzed by immunohistochemistry. Circulating and urinary markers of inflammation and tubular injury were assayed in 21 treated rats over time (1, 2, 4, 8, and 12 weeks of CCl4 administration) and 5 controls. Results: No renal histopathological alterations were found at sacrifice. Comparing treated rats with controls, organic anion transporters were differentially expressed and localized. High serum bile acid values were detected in cirrhotic animals, while caspase-3 staining was negative in both groups. Increased levels of serum inflammatory and urinary tubular injury biomarkers were observed during cirrhosis progression, with a peak after 4 and 8 weeks of treatment. Conclusions: These findings suggest possible adaptive tubular mechanisms for bile acid transporters in response to cirrhosis-induced AKI.
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Affiliation(s)
- Chiara Donadei
- Nephrology, Dialysis and Renal Transplant Unit, IRCCS—Azienda Ospedaliero-Universitaria di Bologna, Alma Mater Studiorum University of Bologna, 40138 Bologna, Italy; (C.D.); (A.A.); (M.C.); (D.C.); (F.Z.)
| | - Andrea Angeletti
- Nephrology, Dialysis and Renal Transplant Unit, IRCCS—Azienda Ospedaliero-Universitaria di Bologna, Alma Mater Studiorum University of Bologna, 40138 Bologna, Italy; (C.D.); (A.A.); (M.C.); (D.C.); (F.Z.)
- Division of Nephrology, Dialysis and Transplantation, IRCCS Istituto Giannina Gaslini, Genoa Largo Gaslini, 16148 Genoa, Italy
| | - Maria Cappuccilli
- Nephrology, Dialysis and Renal Transplant Unit, IRCCS—Azienda Ospedaliero-Universitaria di Bologna, Alma Mater Studiorum University of Bologna, 40138 Bologna, Italy; (C.D.); (A.A.); (M.C.); (D.C.); (F.Z.)
| | - Massimiliano Conti
- Department of Pharmacy and Biotechnology, Alma Mater Studiorum University of Bologna, 40138 Bologna, Italy;
| | - Diletta Conte
- Nephrology, Dialysis and Renal Transplant Unit, IRCCS—Azienda Ospedaliero-Universitaria di Bologna, Alma Mater Studiorum University of Bologna, 40138 Bologna, Italy; (C.D.); (A.A.); (M.C.); (D.C.); (F.Z.)
| | - Fulvia Zappulo
- Nephrology, Dialysis and Renal Transplant Unit, IRCCS—Azienda Ospedaliero-Universitaria di Bologna, Alma Mater Studiorum University of Bologna, 40138 Bologna, Italy; (C.D.); (A.A.); (M.C.); (D.C.); (F.Z.)
| | - Alessio De Giovanni
- Department of Experimental, Diagnostic and Specialty Medicine—DIMES, “F. Addarii” Institute of Oncology and Transplant Pathology, Alma Mater Studiorum University of Bologna, 40138 Bologna, Italy; (A.D.G.); (D.M.)
| | - Deborah Malvi
- Department of Experimental, Diagnostic and Specialty Medicine—DIMES, “F. Addarii” Institute of Oncology and Transplant Pathology, Alma Mater Studiorum University of Bologna, 40138 Bologna, Italy; (A.D.G.); (D.M.)
| | - Rita Aldini
- Department of Chemistry “G. Ciamician”, Alma Mater Studiorum University of Bologna, 40126 Bologna, Italy; (R.A.); (A.R.)
| | - Aldo Roda
- Department of Chemistry “G. Ciamician”, Alma Mater Studiorum University of Bologna, 40126 Bologna, Italy; (R.A.); (A.R.)
| | - Gaetano La Manna
- Nephrology, Dialysis and Renal Transplant Unit, IRCCS—Azienda Ospedaliero-Universitaria di Bologna, Alma Mater Studiorum University of Bologna, 40138 Bologna, Italy; (C.D.); (A.A.); (M.C.); (D.C.); (F.Z.)
- Correspondence: ; Tel.: +39-051-214-4577
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Vansell NR. Mechanisms by Which Inducers of Drug Metabolizing Enzymes Alter Thyroid Hormones in Rats. Drug Metab Dispos 2022; 50:508-517. [DOI: 10.1124/dmd.121.000498] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Accepted: 12/23/2021] [Indexed: 11/22/2022] Open
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The enhanced atorvastatin hepatotoxicity in diabetic rats was partly attributed to the upregulated hepatic Cyp3a and SLCO1B1. Sci Rep 2016; 6:33072. [PMID: 27624558 PMCID: PMC5021965 DOI: 10.1038/srep33072] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Accepted: 08/19/2016] [Indexed: 12/21/2022] Open
Abstract
Liver injury is a common adverse effect of atorvastatin. This study aimed to investigate atorvastatin-induced hepatotoxicity in diabetic rats induced by high-fat diet combined with streptozotocin. The results showed that 40 mg/kg atorvastatin was lethal to diabetic rats, whose mean survival time was 6.2 days. Severe liver injury also occurred in diabetic rats treated with 10 mg/kg and 20 mg/kg atorvastatin. The in vitro results indicated that atorvastatin cytotoxicity in hepatocytes of diabetic rats was more severe than normal and high-fat diet feeding rats. Expressions and activities of hepatic Cyp3a and SLCO1B1 were increased in diabetic rats, which were highly correlated with hepatotoxicity. Antioxidants (glutathione and N-Acetylcysteine), Cyp3a inhibitor ketoconazole and SLCO1B1 inhibitor gemfibrozil suppressed cytotoxicity and ROS formation in primary hepatocytes of diabetic rats. In HepG2 cells, up-regulations of CYP3A4 and SLCO1B1 potentiated hepatotoxicity and ROS generation, whereas knockdowns of CYP3A4 and SLCO1B1 as well as CYP3A4/SLCO1B1 inhibitions showed the opposite effects. Phenobarbital pretreatment was used to induce hepatic Cyp3a and SLCO1B1 in rats. Phenobarbital aggravated atorvastatin-induced hepatotoxicity, while decreased plasma exposure of atorvastatin. All these findings demonstrated that the upregulations of hepatic Cyp3a and SLCO1B1 in diabetic rats potentiated atorvastatin-induced hepatotoxicity via increasing ROS formation.
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Gozalpour E, Greupink R, Wortelboer HM, Bilos A, Schreurs M, Russel FGM, Koenderink JB. Interaction of digitalis-like compounds with liver uptake transporters NTCP, OATP1B1, and OATP1B3. Mol Pharm 2014; 11:1844-55. [PMID: 24754247 DOI: 10.1021/mp400699p] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Digitalis-like compounds (DLCs) such as digoxin, digitoxin, and ouabain, also known as cardiac glycosides, are among the oldest pharmacological treatments for heart failure. The compounds have a narrow therapeutic window, while at the same time, DLC pharmacokinetics is prone to drug-drug interactions at the transport level. Hepatic transporters organic anion transporting polypeptide (OATP) 1B1, OATP1B3, and Na(+)-dependent taurocholate co-transporting polypeptide (NTCP) influence the disposition of a variety of drugs by mediating their uptake from blood into hepatocytes. The interaction of digoxin, digitoxin, and ouabain with hepatic uptake transporters has been studied before. However, here, we systematically investigated a much wider range of structurally related DLCs for their capability to inhibit or to be transported by these transporters in order to better understand the relation between the activity and chemical structure of this compound type. We studied the uptake and inhibitory potency of a series of 14 structurally related DLCs in Chinese hamster ovary cells expressing NTCP (CHO-NTCP) and human embryonic kidney cells expressing OATP1B1 and OATP1B3 (HEK-OATP1B1 and HEK-OATP1B3). The inhibitory effect of the DLCs was measured against taurocholic acid (TCA) uptake in CHO-NTCP cells and against uptake of β-estradiol 17-β-d-glucuronide (E217βG) in HEK-OATP1B1 and HEK-OATP1B3 cells. Proscillaridin A was the most effective inhibitor of NTCP-mediated TCA transport (IC50 = 22 μM), whereas digitoxin and digitoxigenin were the most potent inhibitors of OATP1B1 and OAPTP1B3, with IC50 values of 14.2 and 36 μM, respectively. Additionally, we found that the sugar moiety and hydroxyl groups of the DLCs play different roles in their interaction with NTCP, OATP1B1, and OATP1B3. The sugar moiety decreases the inhibition of NTCP and OATP1B3 transport activity, whereas it enhances the inhibitory potency against OATP1B1. Moreover, the hydroxyl group at position 12 reinforces the inhibition of NTCP but decreases the inhibition of OATP1B1 and OATP1B3. To investigate whether DLCs can be translocated, we quantified their uptake in transporter-expressing cells by LC-MS. We demonstrated that convallatoxin, ouabain, dihydroouabain, and ouabagenin are substrates of OATP1B3. No transport was observed for the other compounds in any of the studied transporters. In summary, this work provides a step toward an improved understanding of the interaction of DLCs with three major hepatic uptake transporters. Ultimately, this can be of use in the development of DLCs that are less prone to transporter-mediated drug-drug interactions.
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Affiliation(s)
- Elnaz Gozalpour
- Department of Pharmacology and Toxicology, Radboud University Medical Centre, Nijmegen Centre for Molecular Life Sciences , 6500 HB Nijmegen, The Netherlands
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7
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Ramboer E, Vanhaecke T, Rogiers V, Vinken M. Primary hepatocyte cultures as prominent in vitro tools to study hepatic drug transporters. Drug Metab Rev 2013; 45:196-217. [PMID: 23368091 DOI: 10.3109/03602532.2012.756010] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Before any drug can be placed on the market, drug efficacy and safety must be ensured through rigorous testing. Animal models are used for this purpose, though currently increasing attention goes to the use of alternative in vitro systems. In particular, liver-based testing platforms that allow the prediction of pharmacokinetic (PK) and pharmacotoxicological properties during the early phase of drug development are of interest. They also enable the screening of potential effects on hepatic drug transporters. The latter are known to affect drug metabolism and disposition, thereby possibly underlying drug-drug interactions, which, in turn, may result in liver toxicity. Clearly, stable in vivo-like functional expression of drug transporters in hepatic in vitro settings is a prerequisite to be applicable in routine PK and pharmacotoxicological testing. In the first part of the article, an updated overview of hepatic drug transporters is provided, followed by a state-of-the-art review of drug-transporter production and activity in primary hepatocyte cultures (PHCs), being the gold-standard in vitro system. Specific focus is hereby put on strategies to maintain long-term functional expression, in casu of drug transporters, in these systems. In the second part, the use of PHCs to assess hepatobiliary transport and transporter-mediated interactions is outlined.
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Affiliation(s)
- Eva Ramboer
- Department of Toxicology, Center for Pharmaceutical Research, Vrije Universiteit Brussel, Brussels, Belgium.
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8
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Zancanella V, Giantin M, Lopparelli RM, Nebbia C, Dacasto M. Tissue distribution and phenobarbital induction of target SLC- and ABC- transporters in cattle. J Vet Pharmacol Ther 2012; 36:358-69. [PMID: 22897113 DOI: 10.1111/j.1365-2885.2012.01427.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2012] [Accepted: 07/07/2012] [Indexed: 01/16/2023]
Abstract
In veterinary pharmaco-toxicological sciences, few data about uptake and efflux drug transporters (DTs) expression and regulation phenomena have been published. In this study, the tissue distribution and transcriptional modulation of solute carrier (SLC) and ATP-binding cassette (ABC) DTs were investigated in cattle orally administered with phenobarbital (PB) by using a quantitative real-time RT-PCR approach. The criterion for target gene selection was the PB-responsiveness in human and rodent model species. All target DTs were expressed in the liver. Only two of the seven PB-responsive target DTs (SLCO1B3 and SLC10A1) were not constitutively expressed in cattle extra-hepatic tissues. The greatest number of DTs (SLCO2B1, ABCB1, ABCC2, ABCG2) were expressed in intestine and testis, followed by, adrenal gland (SLCO2B1, ABCB1, ABCG2), lung (ABCB1, ABCG2), kidney, and skeletal muscle (ABCG2). PB administration never altered DTs mRNA levels, except for an increase in hepatic ABCC2 mRNA and a down-regulation of renal ABCG2. Altogether, these results confirm only to some extent data obtained in humans and laboratory species; clearly, they should be considered a preliminary step for further molecular investigations about species-differences in DT gene expression and regulation as well as in DT expression and function.
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Affiliation(s)
- V Zancanella
- Dipartimento di Biomedicina Comparata e Alimentazione, viale dell'Università 16, Padova, Italy
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Martin LA, Wilson DT, Reuhl KR, Gallo MA, Klaassen CD. Polychlorinated biphenyl congeners that increase the glucuronidation and biliary excretion of thyroxine are distinct from the congeners that enhance the serum disappearance of thyroxine. Drug Metab Dispos 2011; 40:588-95. [PMID: 22187485 DOI: 10.1124/dmd.111.042796] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Polychlorinated biphenyl (PCB) congeners differentially reduce serum thyroxine (T(4)) in rats, but little is known about their ability to affect biliary excretion of T(4). Thus, male Sprague-Dawley rats were orally administered Aroclor-1254, Aroclor-1242 (32 mg/kg per day), PCB-95, PCB-99, PCB-118 (16 mg/kg per day), PCB-126 (40 μg/kg per day), 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) (3.9 μg/kg per day), or corn oil for 7 days. Twenty-four hours after the last dose, [(125)I]T(4) was administered intravenously, and blood, bile, and urine samples were collected for quantifying [(125)I]T(4) and in bile [(125)I]T(4) metabolites. Serum T(4) concentrations were reduced by all treatments, but dramatic reductions occurred in response to Aroclor-1254, PCB-99 [phenobarbital (PB)-type congener], and PCB-118 (mixed-type congener). None of the treatments increased urinary excretion of [(125)I]T(4). Aroclor-1254, PCB-118, TCDD, and PCB-126 (TCDD-type congener) increased biliary excretion of T(4)-glucuronide by 850, 756, 710, and 573%, respectively, corresponding to marked induction of hepatic UDP-glucuronosyltransferase (UGT) activity toward T(4). PCB-95 and PCB-99 did not induce UGT activity; therefore, the increased biliary excretion of T(4)-glucuronide was related to the affinity of congeners for the aryl hydrocarbon receptor. The disappearance of [(125)I]T(4) from serum was rapid (within 15-min) and was increased by Aroclor-1254, PCB-99 and PCB-118. Thus, reductions in serum T(4) in response to PCBs did not always correspond with UGT activity toward T(4) or with increased biliary excretion of T(4)-glucuronide. The rapid disappearance of [(125)I]T(4) from the serum of rats treated with PB-like PCBs suggests that increased tissue uptake of T(4) is an additional mechanism by which PCBs may reduce serum T(4).
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Affiliation(s)
- L A Martin
- Department of Pharmacology, Toxicology and Therapeutics, University of Kansas Medical Center, Kansas City, Kansas 66160, USA
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Ronaldson PT, Finch JD, Demarco KM, Quigley CE, Davis TP. Inflammatory pain signals an increase in functional expression of organic anion transporting polypeptide 1a4 at the blood-brain barrier. J Pharmacol Exp Ther 2010; 336:827-39. [PMID: 21131267 DOI: 10.1124/jpet.110.174151] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Pain is a dominant symptom associated with inflammatory conditions. Pharmacotherapy with opioids may be limited by poor blood-brain barrier (BBB) permeability. One approach that may improve central nervous system (CNS) delivery is to target endogenous BBB transporters such as organic anion-transporting polypeptide 1a4 (Oatp1a4). It is critical to identify and characterize biological mechanisms that enable peripheral pain/inflammation to "transmit" upstream signals and alter CNS drug transport processes. Our goal was to investigate, in vivo, BBB functional expression of Oatp1a4 in animals subjected to peripheral inflammatory pain. Inflammatory pain was induced in female Sprague-Dawley rats (200-250 g) by subcutaneous injection of 3% λ-carrageenan into the right hind paw; control animals were injected with 0.9% saline. In rat brain microvessels, Oatp1a4 expression was increased during acute pain/inflammation. Uptake of taurocholate and [d-penicillamine(2,5)]-enkephalin, two established Oatp substrates, was increased in animals subjected to peripheral pain, suggesting increased Oatp1a4-mediated transport. Inhibition of inflammatory pain with the anti-inflammatory drug diclofenac attenuated these changes in Oatp1a4 functional expression, suggesting that inflammation in the periphery can modulate BBB transporters. In addition, diclofenac prevented changes in the peripheral signaling cytokine transforming growth factor-β1 (TGF-β1) levels and brain microvascular TGF-β receptor expression induced by inflammatory pain. Pretreatment with the pharmacological TGF-β receptor inhibitor 4-[4-(1,3-benzodioxol-5-yl)-5-(2-pyridinyl)-1H-imidazol-2-yl]benzamide (SB431542) increased Oatp1a4 functional expression in λ-carrageenan-treated animals and saline controls, suggesting that TGF-β signaling is involved in Oatp1a4 regulation at the BBB. Our findings indicate that BBB transporters (i.e., Oatp1a4) can be targeted during drug development to improve CNS delivery of highly promising therapeutics.
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Affiliation(s)
- Patrick T Ronaldson
- Department of Medical Pharmacology, College of Medicine, University of Arizona, Tucson, AZ 85724-5050, USA.
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Gu X, Manautou JE. Regulation of hepatic ABCC transporters by xenobiotics and in disease states. Drug Metab Rev 2010; 42:482-538. [PMID: 20233023 DOI: 10.3109/03602531003654915] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The subfamily of ABCC transporters consists of 13 members in mammals, including the multidrug resistance-associated proteins (MRPs), sulfonylurea receptors (SURs), and the cystic fibrosis transmembrane conductance regulator (CFTR). These proteins play roles in chemical detoxification, disposition, and normal cell physiology. ABCC transporters are expressed differentially in the liver and are regulated at the transcription and translation level. Their expression and function are also controlled by post-translational modification and membrane-trafficking events. These processes are tightly regulated. Information about alterations in the expression of hepatobiliary ABCC transporters could provide important insights into the pathogenesis of diseases and disposition of xenobiotics. In this review, we describe the regulation of hepatic ABCC transporters in humans and rodents by a variety of xenobiotics, under disease states and in genetically modified animal models deficient in transcription factors, transporters, and cell-signaling molecules.
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Affiliation(s)
- Xinsheng Gu
- Department of Pharmaceutical Sciences, University of Connecticut, Storrs, 06269, USA
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12
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Zhang H, Song YN, Liu WG, Guo XL, Yu LG. Regulation and role of organic anion-transporting polypeptides (OATPs) in drug delivery at the choroid plexus. J Clin Neurosci 2010; 17:679-84. [DOI: 10.1016/j.jocn.2009.11.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2009] [Revised: 09/28/2009] [Accepted: 11/10/2009] [Indexed: 11/25/2022]
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13
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Stahl S, Davies MR, Cook DI, Graham MJ. Nuclear hormone receptor-dependent regulation of hepatic transporters and their role in the adaptive response in cholestasis. Xenobiotica 2008; 38:725-77. [DOI: 10.1080/00498250802105593] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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14
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Teng S, Piquette-Miller M. Regulation of transporters by nuclear hormone receptors: implications during inflammation. Mol Pharm 2007; 5:67-76. [PMID: 18072749 DOI: 10.1021/mp700102q] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Membrane transporters play a critical role in the absorption, distribution, and elimination of both endogenous substrates and xenobiotics. Defects in transporter function can lead to altered drug disposition including toxicity or loss of efficacy. Inflammation is one condition during which variable drug response has been demonstrated, and this can be attributed, at least in part, to changes in the expression of transporter genes. Thus, knowledge of the mechanisms behind transporter regulation can significantly contribute to our ability to predict variations in drug disposition among individuals and during inflammatory disease. The discovery of several xenobiotic-activated nuclear hormone receptors during the past decade including the pregnane X receptor, constitutive androstane receptor, and farnesoid X receptor has contributed greatly toward this endeavor. These receptors regulate the expression of transporters such as P-glycoprotein, MRP2, MRP3, BCRP, and OATP2 (Oatp1a1/OATP1B1), all of which undergo altered expression during an inflammatory response. Nuclear receptors may therefore play an important role in mediating this effect. This review presents what is currently known about the role of nuclear receptors in transporter regulation during inflammation. The use of this knowledge toward understanding interindividual variation in drug response and drug interactions during inflammation as well toward the development of therapeutics to treat transporter-related diseases will also be discussed.
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Affiliation(s)
- Shirley Teng
- Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, M5S 3M2, Canada
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Donner MG, Schumacher S, Warskulat U, Heinemann J, Häussinger D. Obstructive cholestasis induces TNF-alpha- and IL-1 -mediated periportal downregulation of Bsep and zonal regulation of Ntcp, Oatp1a4, and Oatp1b2. Am J Physiol Gastrointest Liver Physiol 2007; 293:G1134-46. [PMID: 17916651 DOI: 10.1152/ajpgi.00079.2007] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Inverse acinar regulation of Mrp2 and 3 represents an adaptive response to hepatocellular cholestatic injury. We studied whether obstructive cholestasis (bile duct ligation) and LPS treatment affect the zonal expression of Bsep (Abcb11), Mrp4 (Abcc4), Ntcp (Slc10a1), and Oatp isoforms (Slco1a1, Slco1a4, and slco1b2) in rat liver, as analyzed by semiquantitative immunofluorescence. Contribution of TNF-alpha and IL-1beta to transporter zonation in obstructive cholestasis was studied by cytokine inactivation. In normal liver Bsep, Mrp4, Ntcp, and Oatp1a1 were homogeneously distributed in the acinus, whereas Oatp1a4 and Oatp1b2 expression increased from zone 1 to 3. Glutamine synthetase-positive pericentral hepatocytes exhibited markedly lower Oatp1a4 expression than the remaining zone 3 hepatocytes. In cholestatic liver Bsep and Ntcp immunofluorescence in periportal hepatocytes significantly decreased to 66 +/- 4% (P < 0.01) and 67 +/- 7% (P < 0.05), whereas it was not altered in pericentral hepatocytes. Oatp1a4 was significantly induced in hepatocytes with a primarily low expression, i.e., in periportal hepatocytes and in glutamine synthetase-positive pericentral hepatocytes. Likewise, Oatp1b2 was upregulated in periportal hepatocytes. Mrp4 zonal induction was homogeneous. Inactivation of TNF-alpha and IL-1beta prevented periportal downregulation of Bsep. Recruitment of neutrophils and polymorphonuclear cells mainly occurred in the periportal zone. Likewise, IL-1beta induction was largely found periportally. No significant transporter zonation was seen following LPS treatment. In conclusion, zonal downregulation of Bsep in obstructive cholestasis is associated with portal inflammation and is mediated by TNF-alpha and IL-1beta. Periportal downregulation of Ntcp and induction of Oatp1a4 and Oatp1b2 may represent adaptive mechanisms to reduce cholestatic injury in hepatocytes with profound downregulation of Bsep and Mrp2.
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Affiliation(s)
- Markus G Donner
- Dept. of Gastroenterology, Hepatology and Infectious Diseases, Heinrich Heine Univ. Düsseldorf, Moorenstrasse 5, D-40225 Düsseldorf, Germany.
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16
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Abstract
Nuclear receptors (NRs) are attractive drug targets due to their role in regulation of a wide range of physiologic responses. In addition to providing therapeutic value, many pharmaceutical agents along with environmental chemicals are ligands for NRs and can cause adverse health effects that are directly related to activation of NRs. Identifying the molecular events that produce a toxic response may be confounded by the fact that there is a significant overlap in the biological processes that NRs regulate. Microarrays and other methods for gene expression profiling have served as useful, sensitive tools for discerning the mechanisms by which therapeutics and environmental chemicals invoke toxic effects. The capability to probe thousands of genes simultaneously has made genomics a prime technology for identifying drug targets, biomarkers of exposure/toxicity and key players in the mechanisms of disease. The complex intertwining networks regulated by NRs are hard to probe comprehensively without global approaches and genomics has become a key technology that facilitates our understanding of NR-dependent and -independent events. The future of drug discovery, design and optimization, and risk assessment of chemical toxicants that activate NRs will inevitably involve genomic profiling. This review will focus on genomics studies related to PPAR, CAR, PXR, RXR, LXR, FXR, and AHR.
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Affiliation(s)
- Courtney G Woods
- Department of Environmental Sciences and Engineering, University of North Carolina, Chapel Hill, North Carolina 27599-7431, USA
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17
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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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18
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Chen C, Cheng X, Dieter MZ, Tanaka Y, Klaassen CD. Activation of cAMP-dependent signaling pathway induces mouse organic anion transporting polypeptide 2 expression. Mol Pharmacol 2007; 71:1159-64. [PMID: 17244698 DOI: 10.1124/mol.106.030841] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Rodent Oatp2 is a hepatic uptake transporter for such compounds as cardiac glycosides. In the present study, we found that fasting resulted in a 2-fold induction of Oatp2 expression in liver of mice. Because the cAMP-protein kinase A (PKA) signaling pathway is activated during fasting, the role of this pathway in Oatp2 induction during fasting was examined. In Hepa-1c1c7 cells, adenylyl cyclase activator forskolin as well as two cellular membrane-permeable cAMP analogs, dibutyryl cAMP and 8-bromo-cAMP, induced Oatp2 mRNA expression in a time- and dose-dependent manner. These three chemicals induced reporter gene activity in cells transfected with a luciferase reporter gene construct containing a 7.6-kilobase (kb) 5'-flanking region of mouse Oatp2. Transient transfection of cells with 5'-deletion constructs derived from the 7.6-kb Oatp2 promoter reporter gene construct, as well as 7.6-kb constructs in which a consensus cAMP response element (CRE) half-site CGTCA (-1808/-1804 bp) was mutated or deleted, confirms that this CRE site was required for the induction of luciferase activity by forskolin. Luciferase activity driven by the Oatp2 promoter containing this CRE site was induced in cells cotransfected with a plasmid encoding the protein kinase A catalytic subunit. Cotransfection of cells with a plasmid encoding the dominant-negative CRE binding protein (CREB) completely abolished the inducibility of the reporter gene activity by forskolin. In conclusion, induction of Oatp2 expression in liver of fasted mice may be caused by activation of the cAMP-dependent signaling pathway, with the CRE site (-1808/-1804) and CREB being the cis- and trans-acting factors mediating the induction, respectively.
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Affiliation(s)
- Chuan Chen
- Department of Pharmacology, Toxicology, and Therapeutics, University of Kansas Medical Center, 3901 Rainbow Boulevard, Kansas City, KS 66160, USA
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19
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Liu L, Pang KS. An integrated approach to model hepatic drug clearance. Eur J Pharm Sci 2006; 29:215-30. [PMID: 16806855 DOI: 10.1016/j.ejps.2006.05.007] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2006] [Accepted: 05/16/2006] [Indexed: 11/15/2022]
Abstract
It has been well accepted that hepatic drug extraction depends on the blood flow, vascular binding, transmembrane barriers, transporters, enzymes and cosubstrate and their zonal heterogeneity. Models of hepatic drug clearances have been appraised with respect to their utility in predicting drug removal by the liver. Among these models, the "well-stirred" model is the simplest since it assumes venous equilibration, with drug emerging from the outflow being in equilibrium with drug within the liver, and the concentration is the same throughout. The "parallel tube" and dispersion models, and distributed model of Goresky and co-workers have been used to account for the observed sinusoidal concentration gradient from the inlet and outlet. Departure from these models exists to include heterogeneity in flow, enzymes, and transporters. This article utilized the physiologically based pharmacokinetic (PBPK) liver model and its extension that include heterogeneity in enzymes and transporters to illustrate how in vitro uptake and metabolic data from zonal hepatocytes on transport and enzymes may be used to predict the kinetics of removal in the intact liver; binding data were also necessary. In doing so, an integrative platform was provided to examine determinants of hepatic drug clearance. We used enalapril and digoxin as examples, and described a simple liver PBPK model that included transmembrane transport and metabolism occurring behind the membrane, and a zonal model in which the PBPK model was expanded three sets of sub-compartments that are arranged sequentially to represent zones 1, 2, and 3 along the flow path. The latter model readily accommodated the heterogeneous distribution of hepatic enzymes and transporters. Transport and metabolic data, piecewise information that served as initial estimates, allowed for the unknown efflux and other intrinsic clearances to be estimated. The simple or zonal PBPK model provides predictive views on the hepatic removal of drugs and metabolites.
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Affiliation(s)
- Lichuan Liu
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, 19 Russell Street, Toronto, Ontario, Canada M5S 2S2
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20
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Cowie DE, Weaver RJ, Hawksworth GM. PXR and CAR are implicated in Oatp1a4 induction in vivo and in vitro. Toxicology 2006. [DOI: 10.1016/j.tox.2006.05.062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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21
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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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22
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Wagner M, Halilbasic E, Marschall HU, Zollner G, Fickert P, Langner C, Zatloukal K, Denk H, Trauner M. CAR and PXR agonists stimulate hepatic bile acid and bilirubin detoxification and elimination pathways in mice. Hepatology 2005; 42:420-30. [PMID: 15986414 DOI: 10.1002/hep.20784] [Citation(s) in RCA: 236] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Induction of hepatic phase I/II detoxification enzymes and alternative excretory pumps may limit hepatocellular accumulation of toxic biliary compounds in cholestasis. Because the nuclear xenobiotic receptors constitutive androstane receptor (CAR) and pregnane X receptor (PXR) regulate involved enzymes and transporters, we aimed to induce adaptive alternative pathways with different CAR and PXR agonists in vivo. Mice were treated with the CAR agonists phenobarbital and 1,4-bis-[2-(3,5-dichlorpyridyloxy)]benzene, as well as the PXR agonists atorvastatin and pregnenolone-16alpha-carbonitrile. Hepatic bile acid and bilirubin-metabolizing/detoxifying enzymes (Cyp2b10, Cyp3a11, Ugt1a1, Sult2a1), their regulatory nuclear receptors (CAR, PXR, farnesoid X receptor), and bile acid/organic anion and lipid transporters (Ntcp, Oatp1,2,4, Bsep, Mrp2-4, Mdr2, Abcg5/8, Asbt) in the liver and kidney were analyzed via reverse-transcriptase polymerase chain reaction and Western blotting. Potential functional relevance was tested in common bile duct ligation (CBDL). CAR agonists induced Mrp2-4 and Oatp2; PXR agonists induced only Mrp3 and Oatp2. Both PXR and CAR agonists profoundly stimulated bile acid-hydroxylating/detoxifying enzymes Cyp3a11 and Cyp2b10. In addition, CAR agonists upregulated bile acid-sulfating Sult2a1 and bilirubin-glucuronidating Ugt1a1. These changes were accompanied by reduced serum levels of bilirubin and bile acids in healthy and CBDL mice and by increased levels of polyhydroxylated bile acids in serum and urine of cholestatic mice. Atorvastatin significantly increased Oatp2, Mdr2, and Asbt, while other transporters and enzymes were moderately affected. In conclusion, administration of specific CAR or PXR ligands results in coordinated stimulation of major hepatic bile acid/bilirubin metabolizing and detoxifying enzymes and hepatic key alternative efflux systems, effects that are predicted to counteract cholestasis.
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Affiliation(s)
- Martin Wagner
- Laboratory of Experimental and Molecular Hepatology, Division of Gastroenterology and Hepatology, Department of Medicine, Medical University Graz, Auenbruggerplatz 15, A-8036 Graz, Austria
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23
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Liu L, Mak E, Tirona RG, Tan E, Novikoff PM, Wang P, Wolkoff AW, Pang KS. Vascular binding, blood flow, transporter, and enzyme interactions on the processing of digoxin in rat liver. J Pharmacol Exp Ther 2005; 315:433-48. [PMID: 15994370 DOI: 10.1124/jpet.105.088039] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The roles of vascular binding, flow, transporters, and enzymes as determinants of the clearance of digoxin were examined in the rat liver. Digoxin is metabolized by Cyp3a and utilizes the organic anion transporting polypeptide 2 (Oatp2) and P-glycoprotein (Pgp) for influx and excretion, respectively. Uptake of digoxin was found to be similar among rat periportal (PP) and perivenous (PV) hepatocytes isolated by the digitonin-collagenase method. The Km values for uptake were 180 +/- 112 and 390 +/- 406 nM, Vmax values were 13 +/- 8 and 18 +/- 4.9 pmol/min/mg protein, and nonsaturable components were 9.2 +/- 1.3 and 10.7 +/- 2.5 microl/min/mg for PP and PV, respectively. The evenness of distribution of Oatp2 and Pgp was confirmed by Western blotting and confocal immunofluorescent microscopy. When digoxin was recirculated to the rat liver preparation in Krebs-Henseleit bicarbonate (KHB) for 3 h in absence or presence of 1% bovine serum albumin (BSA) and 20% red blood cell (rbc) at flow rates of 40 and 10 ml/min, respectively, biexponential decays were observed. Fitted results based on compartmental analyses revealed a higher clearance (0.244 +/- 0.082 ml/min/g) for KHB-perfused livers over the rbc-albumin-perfused livers (0.114 +/- 0.057 ml/min/g) (P < 0.05). We further found that binding of digoxin to 1% BSA was modest (unbound fraction = 0.64), whereas binding to rbc was associated with slow on (0.468 +/- 0.021 min(-1)) and off (1.81 +/- 0.12 min(-1)) rate constants. We then used a zonal, physiologically based pharmacokinetic model to show that the difference in digoxin clearance was attributed to binding to BSA and rbc and not to the difference in flow rate and that clearance was unaffected by transporter or enzyme heterogeneity.
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Affiliation(s)
- Lichuan Liu
- Department of Pharmaceutical Sciences, University of Toronto, Toronto, ON, Canada
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24
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Kullak-Ublick GA, Becker MB. Regulation of drug and bile salt transporters in liver and intestine. Drug Metab Rev 2004; 35:305-17. [PMID: 14705863 DOI: 10.1081/dmr-120026398] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Major determinants of the bioavailability of drugs are the degree of intestinal absorption and the hepatic first-pass effect. Drugs need to overcome several membrane barriers before reaching the systemic circulation, each of which expresses an array of specialized transport proteins for drug uptake or efflux. The P-glycoprotein MDR1 (multidrug resistance gene product, ABCB1) is expressed at the apical surface of enterocytes, where it mediates the efflux of xenobiotics into the intestinal lumen before these can access the portal circulation. Increased expression of MDR1 reduces the bioavailability of MDR1 substrates such as digoxin, cyclosporin, and taxol. Numerous xenobiotics can induce the MDR1 gene through activation of the nuclear pregnane X receptor (PXR). This explains the risk for drug interactions that is inherent to pharmacotherapy with PXR ligands such as rifampin, phenobarbital, statins, and St. John's wort. Other PXR-regulated genes include cytochrome P450 3A4, the digoxin and bile salt transporter Oatp2 (organic anion transporting polypeptide 2, Slc01a4) of the basolateral hepatocyte membrane, and the xenobiotic efflux pump Mrp2 (multidrug resistance associated protein 2, Abcc2) of the canalicular hepatocyte membrane. A second orphan nuclear receptor that is activated by xenobiotics is the constitutive androstane receptor (CAR), which induces Mrp2 and Mrp3 (Abcc3). The PXR and CAR are thus important "xenosensors" that mediate drug-induced activation of the detoxifying transport and enzyme systems in liver and intestine.
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Affiliation(s)
- Gerd A Kullak-Ublick
- Laboratory of Molecular Gastroenterology and Hepatology, Division of Clinical Pharmacology and Toxicology, Department of Internal Medicine, University Hospital, Zurich, Switzerland.
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25
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Prados MD, Yung WKA, Jaeckle KA, Robins HI, Mehta MP, Fine HA, Wen PY, Cloughesy TF, Chang SM, Nicholas MK, Schiff D, Greenberg HS, Junck L, Fink KL, Hess KR, Kuhn J. Phase 1 trial of irinotecan (CPT-11) in patients with recurrent malignant glioma: a North American Brain Tumor Consortium study. Neuro Oncol 2004; 6:44-54. [PMID: 14769140 PMCID: PMC1871968 DOI: 10.1215/s1152851703000292] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2003] [Accepted: 09/22/2003] [Indexed: 01/29/2023] Open
Abstract
This study was conducted to determine the maximum tolerated dose and dose-limiting toxicity of irinotecan (CPT-11) administered every 3 weeks to adults with progressive malignant glioma who were treated with enzyme inducing antiepileptic drug (EIAED) therapy, and to compare the pharmacokinetics with those in patients not on EIAED therapy treated at the recommended phase 2 dose for other cancers. The CPT-11 dose was 350 mg/m(2) i.v. every 3 weeks and remained fixed in patients not on EIAED therapy, but the dose was escalated by 50-mg/m(2) increments in patients on EIAED therapy. CPT-11 and its metabolites SN-38, SN-38 glucuronide (SN-38G), and APC (7-ethyl-10[4-N-(5 aminopentanoic acid)-1-piperidine]-carbonyloxycamptothecin) were characterized in both groups. Patients on EIAEDs received 350 to 800 mg/m(2) of CPT-11. Dose-limiting toxicity was due to grade 3 diarrhea despite maximal doses of loperamide. The systemic levels of CPT-11, APC, SN-38G, and SN-38 were all lower in the EIAED group. There was a moderate-to-fair relationship between CPT-11 dose and the area under the curve (AUC) for CPT-11 and APC over the 2, but no relationship dosage range of 350 to 800 mg/m between CPT-11 dose and the AUC for SN-38 or SN-38G. At the 750-mg/m(2) dose, the AUC for CPT-11 (21.6 microg x h/ml) matched the AUC (21.6 microg x h/ml) in the non-EIAED group treated with 350 mg/m(2) of CPT-11. We conclude that the recommended phase 2 dose of CPT-11 for patients on EIAEDs is 750 mg/m(2) when given every 3 weeks. A phase 2 study of patients with recurrent malignant glioma is ongoing to assess the efficacy of CPT-11 when the dose is stratified according to the use of EIAEDs.
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Affiliation(s)
- Michael D Prados
- Department of Neurological Surgery, University of California at San Francisco, San Francisco, CA 94143, USA.
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26
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Kullak-Ublick GA, Stieger B, Meier PJ. Enterohepatic bile salt transporters in normal physiology and liver disease. Gastroenterology 2004; 126:322-42. [PMID: 14699511 DOI: 10.1053/j.gastro.2003.06.005] [Citation(s) in RCA: 458] [Impact Index Per Article: 22.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The vectorial transport of bile salts from blood into bile is essential for the generation of bile flow, solubilization of cholesterol in bile, and emulsification of lipids in the intestine. Major transport proteins involved in the enterohepatic circulation of bile salts include the hepatocellular bile salt export pump (BSEP, ABCB11), the apical sodium-dependent bile salt transporter (ASBT, SLC10A2) in cholangiocytes and enterocytes, the sodium-dependent hepatocyte bile salt uptake system NTCP (SLC10A1), the organic anion transporting polypeptides OATP-C (SLC21A6), OATP8 (SLC21A8) and OATP-A (SLC21A3), and the multidrug resistance protein MRP3 (ABCC3). Synthesis and transport of bile salts are intricately linked processes that undergo extensive feedback and feed-forward regulation by transcriptional and posttranscriptional mechanisms. A key regulator of hepatocellular bile salt homeostasis is the bile acid receptor/farnesoid X receptor FXR, which activates transcription of the BSEP and OATP8 genes and of the small heterodimer partner 1 (SHP). SHP is a transcriptional repressor that mediates bile acid-induced repression of the bile salt uptake systems rat Ntcp and human OATP-C. A nuclear receptor that activates rodent Oatp2 (Slc21a5) and human MRP2 (ABCC2) is the pregnane X receptor/steroid X receptor PXR/SXR. Intracellular trafficking and membrane insertion of bile salt transporters is regulated by lipid, protein, and extracellular signal-related kinases in response to physiologic stimuli such as cyclic adenosine monophosphate or taurocholate. Finally, dysfunction of individual bile salt transporters such as BSEP, on account of genetic mutations, steric inhibition, suppression of gene expression, or disturbed signaling, is an important cause of cholestatic liver disease.
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Affiliation(s)
- Gerd A Kullak-Ublick
- Division of Clinical Pharmacology and Toxicology, Department of Internal Medicine, University Hospital, Zurich, Switzerland
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27
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Pastor CM, Planchamp C, Pochon S, Lorusso V, Montet X, Mayer J, Terrier F, Vallee JP. Kinetics of gadobenate dimeglumine in isolated perfused rat liver: MR imaging evaluation. Radiology 2003; 229:119-25. [PMID: 12944603 DOI: 10.1148/radiol.2291020726] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
PURPOSE To compare in the entire liver, the hepatic kinetics of gadobenate dimeglumine (Gd-BOPTA) and gadopentetate dimeglumine (Gd-DTPA) and to evaluate the hepatic transport of Gd-BOPTA. MATERIALS AND METHODS The authors studied both contrast agents in isolated perfused rat livers by measuring the magnetic resonance (MR) signal intensity (SI) in 12 rats, as well as the gadolinium concentrations in hepatic tissues in 42 rats. The intrahepatic transport of Gd-BOPTA was investigated with pharmacologic antagonism by using bromosulfophthalein. MR imaging was performed at 1.5 T with a fast gradient-echo T1-weighted MR sequence. RESULTS The hepatic kinetics based on the MR SI measured over time showed a rapid steady state during Gd-DTPA perfusion, while the SI continuously increased during the 30-minute Gd-BOPTA perfusion period. The pharmacokinetic modeling indicated that the half-lives of Gd-DTPA entry and exit were identical (mean, 1.3 minutes +/- 0.9 [standard error of mean]) and shorter than those observed with Gd-BOPTA (P <.001). The uptake of Gd-BOPTA was faster (mean half-life, 4.8 minutes +/- 0.3) than the washout (mean half-life, 17.5 minutes +/- 2.8) (P =.001). The combined perfusion of bromosulfophthalein and Gd-BOPTA decreased the SI enhancement in comparison with the perfusion of Gd-BOPTA alone (mean, 0.56 +/- 0.03 vs 2.54 +/- 0.39, P <.001). The entry and exit kinetic parameters obtained during the perfusion of Gd-BOPTA plus bromosulfophthalein were identical and comparable to those obtained during Gd-DTPA perfusion (P =.95). Acute bile duct ligation did not interfere with the uptake of Gd-BOPTA in hepatocytes, but it slowed down the excretion by approximately 50%. Measurements of gadolinium concentrations in hepatic tissues confirmed these findings. CONCLUSION In the liver, the hepatospecific contrast agent Gd-BOPTA enters into hepatocytes likely through the organic anion transporting peptide 1.
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Affiliation(s)
- Catherine M Pastor
- Department of Radiology, Hôpital Universitaire de Genève, Rue Micheli-du-Crest 24, Bâtiment C, Room 6-795, 1211 Geneva 14, Switzerland.
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28
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Patel NJ, Zamek-Gliszczynski MJ, Zhang P, Han YH, Jansen PLM, Meier PJ, Stieger B, Brouwer KLR. Phenobarbital alters hepatic Mrp2 function by direct and indirect interactions. Mol Pharmacol 2003; 64:154-9. [PMID: 12815171 DOI: 10.1124/mol.64.1.154] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Phenobarbital (PB) treatment impairs the biliary excretion of some organic anions. One mechanism may involve direct competition for biliary excretion by PB and/or a PB metabolite. Alternatively, PB may alter the expression and/or function of hepatic organic anion transport proteins. The role of multidrug resistance-associated protein 2 (Mrp2) in the biliary excretion of PB and metabolites was studied using isolated perfused livers (IPLs) from Wistar and Mrp2-deficient TR- rats. In normal livers, 4.19 +/- 0.53% of the PB dose was recovered in bile as PB metabolites [2.21 +/- 0.69% as 5-ethyl-5-(4-OH phenyl) barbituric acid (PBOH)-glucuronide; 1.98 +/- 0.09% as PBOH-sulfate]. In TR- livers, only PBOH-sulfate was recovered in bile (0.35 +/- 0.16% of dose) during the 2-h perfusion. Mrp2 message was increased (2.3-fold) by PB pretreatment (80 mg/kg i.p. x 4 days) but decreased to control values after a 48-h washout. Mrp2 protein was increased slightly in PB-treated livers and remained slightly elevated after a 24-h washout, but it was decreased significantly to 62 +/-7% of control values after a 48-h washout. The 120-min cumulative biliary excretion of the Mrp2 substrate 5-(and-6)-carboxy-2', 7'-dichlorofluorescein in IPLs from PB-treated rats after a 48-h washout was significantly lower than in vehicle-treated livers (66.3 +/- 9.2% versus 83.4 +/- 2.4% of the dose, respectively). These data support two mechanisms for impaired biliary excretion of some organic anions by PB treatment: 1) PBOH-glucuronide is a substrate for Mrp2 and may compete with other organic anions for biliary excretion and 2) Mrp2 protein expression and functional capacity is decreased 48 h after PB treatment.
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Affiliation(s)
- Nita J Patel
- Division of Drug Delivery and Disposition, School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
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29
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Huang W, Zhang J, Chua SS, Qatanani M, Han Y, Granata R, Moore DD. Induction of bilirubin clearance by the constitutive androstane receptor (CAR). Proc Natl Acad Sci U S A 2003; 100:4156-61. [PMID: 12644704 PMCID: PMC153064 DOI: 10.1073/pnas.0630614100] [Citation(s) in RCA: 288] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2002] [Accepted: 01/30/2003] [Indexed: 01/03/2023] Open
Abstract
Bilirubin clearance is one of the numerous important functions of the liver. Defects in this process result in jaundice, which is particularly common in neonates. Elevated bilirubin levels can be decreased by treatment with phenobarbital. Because the nuclear hormone receptor constitutive androstane receptor (CAR) mediates hepatic effects of this xenobiotic inducer, we hypothesized that CAR could be a regulator of bilirubin clearance. Activation of the nuclear hormone receptor CAR increases hepatic expression of each of five components of the bilirubin-clearance pathway. This induction is absent in homozygous CAR null mice but is observed in mice expressing human CAR instead of mouse CAR. Pretreatment with xenobiotic inducers markedly increases the rate of clearance of an exogenous bilirubin load in wild-type but not CAR knockout animals. Bilirubin itself can also activate CAR, and mice lacking CAR are defective in clearing chronically elevated bilirubin levels. Unexpectedly, CAR expression is very low in livers of neonatal mice and humans. We conclude that CAR directs a protective response to elevated bilirubin levels and suggest that a functional deficit of CAR activity may contribute to neonatal jaundice.
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Affiliation(s)
- Wendong Huang
- Department of Molecular and Cellular Biology, Baylor College of Medicine, 1 Baylor Plaza, Houston, TX 77030, USA
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30
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Trauner M, Boyer JL. Bile salt transporters: molecular characterization, function, and regulation. Physiol Rev 2003; 83:633-71. [PMID: 12663868 DOI: 10.1152/physrev.00027.2002] [Citation(s) in RCA: 661] [Impact Index Per Article: 31.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Molecular medicine has led to rapid advances in the characterization of hepatobiliary transport systems that determine the uptake and excretion of bile salts and other biliary constituents in the liver and extrahepatic tissues. The bile salt pool undergoes an enterohepatic circulation that is regulated by distinct bile salt transport proteins, including the canalicular bile salt export pump BSEP (ABCB11), the ileal Na(+)-dependent bile salt transporter ISBT (SLC10A2), and the hepatic sinusoidal Na(+)- taurocholate cotransporting polypeptide NTCP (SLC10A1). Other bile salt transporters include the organic anion transporting polypeptides OATPs (SLC21A) and the multidrug resistance-associated proteins 2 and 3 MRP2,3 (ABCC2,3). Bile salt transporters are also present in cholangiocytes, the renal proximal tubule, and the placenta. Expression of these transport proteins is regulated by both transcriptional and posttranscriptional events, with the former involving nuclear hormone receptors where bile salts function as specific ligands. During bile secretory failure (cholestasis), bile salt transport proteins undergo adaptive responses that serve to protect the liver from bile salt retention and which facilitate extrahepatic routes of bile salt excretion. This review is a comprehensive summary of current knowledge of the molecular characterization, function, and regulation of bile salt transporters in normal physiology and in cholestatic liver disease and liver regeneration.
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Affiliation(s)
- Michael Trauner
- Division of Gastroenterology and Hepatology, Department of Internal Medicine, Karl-Franzens University, School of Medicine, Graz, Austria
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31
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Abstract
Together with drug metabolising enzymes, transmembrane transporters are important determinants of drug metabolism and drug clearance by the liver. Hepatic uptake of organic anions, cations, prostaglandins and bile salts is supported by dedicated transporter proteins in the basolateral (sinusoidal) membrane of hepatocytes: OATPs, OATs, OCTs, PGTs and NTCP, respectively. ATP-binding cassette (ABC) transporter proteins in the canalicular membrane of hepatocytes mediate the hepatic efflux of drugs, bile salts and metabolites against a steep concentration gradient from liver to bile. This transport is driven by ATP hydrolysis. Drugs, endogenous metabolites, bile salts and cytokines affect the expression levels of these transporters. They act through a family of ligand-activated transcription factors, the nuclear hormone receptors. Consequently, the levels of the various transporter proteins are subject to genetic polymorphism in the encoding genes as well as in these transcription factors. Adverse drug reactions may be caused by genetic or disease-induced variations of transporter expression or drug-drug interactions at the level of these transporters.
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Affiliation(s)
- Klaas Nico Faber
- Department of Gastroenterology and Hepatology, State University Groningen, Hanzeplein 1, 9713 GZ Groningen, The Netherlands
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32
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Hagenbuch B, Meier PJ. The superfamily of organic anion transporting polypeptides. BIOCHIMICA ET BIOPHYSICA ACTA 2003; 1609:1-18. [PMID: 12507753 DOI: 10.1016/s0005-2736(02)00633-8] [Citation(s) in RCA: 587] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Organic anion transporting polypeptides (Oatps/OATPs) form a growing gene superfamily and mediate transport of a wide spectrum of amphipathic organic solutes. Different Oatps/OATPs have partially overlapping and partially distinct substrate preferences for organic solutes such as bile salts, steroid conjugates, thyroid hormones, anionic oligopeptides, drugs, toxins and other xenobiotics. While some Oatps/OATPs are preferentially or even selectively expressed in one tissue such as the liver, others are expressed in multiple organs including the blood-brain barrier (BBB), choroid plexus, lung, heart, intestine, kidney, placenta and testis. This review summarizes the actual state of the rapidly expanding OATP superfamily and covers the structural properties, the genomic classification, the phylogenetic relationships and the functional transport characteristics. In addition, we propose a new species independent and open ended nomenclature and classification system, which is based on divergent evolution and agrees with the guidelines of the Human Genome Nomenclature Committee.
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Affiliation(s)
- B Hagenbuch
- Division of Clinical Pharmacology and Toxicology, Department of Medicine, University Hospital, CH-8091 Zurich, Switzerland.
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33
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Akita H, Suzuki H, Sugiyama Y. Sinusoidal efflux of taurocholate correlates with the hepatic expression level of Mrp3. Biochem Biophys Res Commun 2002; 299:681-7. [PMID: 12470631 DOI: 10.1016/s0006-291x(02)02723-7] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Multidrug resistance-associated protein 3 (Mrp3/ABCC3), which can mediate the cellular extrusion of bile acids, is induced on the hepatic sinusoidal membrane of Mrp2/ABCC2-deficient rats (Eisai hyperbilirubinemic rats; EHBRs) and phenobarbital-treated Sprague-Dawley rats. In the present study, the correlation between the sinusoidal efflux clearance (PS(eff)) of [3H]taurocholate (TC) and the hepatic expression of Mrp3 was investigated using perfused liver from these rats. A significant correlation was observed between the PS(eff) and the hepatic expression level of Mrp3, suggesting a contribution by Mrp3 to the sinusoidal efflux of TC. The results of the kinetic analysis also suggested that other transporter(s) on the sinusoidal plasma membrane may participate in the efflux of TC under physiological conditions. The contribution of Mrp3 to the sinusoidal efflux of TC in EHBRs and phenobarbital (80 and 40 mg/kg)-treated rats was revealed to be 58%, 48%, and 31%, respectively.
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Affiliation(s)
- Hidetaka Akita
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
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34
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Abstract
The organic anion-transporting polypeptides (OATP) represent a family of proteins responsible for the membrane transport of a large number of endogenous and xenobiotic compounds with diverse chemical characteristics. OATPs are expressed in liver, kidney, brain and intestine suggesting that they may play a critical role in drug disposition. Naturally occurring polymorphisms in OATPs are currently being identified and for some, in vitro transport activities have been characterized. In this article, we review the molecular, biochemical and pharmacological aspects of known human OATPs including the presence and functional relevance of genetic polymorphisms.
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Affiliation(s)
- Rommel G Tirona
- Division of Clinical Pharmacology, Department of Medicine, 572 RRB-1, 23rd Ave @ Pierce Ave, Vanderbilt University School of Medicine, Nashville, TN 37232-6602, USA
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35
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Suzuki H, Sugiyama Y. Single nucleotide polymorphisms in multidrug resistance associated protein 2 (MRP2/ABCC2): its impact on drug disposition. Adv Drug Deliv Rev 2002; 54:1311-31. [PMID: 12406647 DOI: 10.1016/s0169-409x(02)00075-3] [Citation(s) in RCA: 170] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Multidrug resistance associated protein 2 (MRP2/ABCC2), expressed on the bile canalicular membrane, plays an important role in the biliary excretion of various kinds of substrates. In addition, MRP2 is also expressed on the apical membrane of epithelial cells such as enterocytes. It is possible that the inter-individual difference in the function of MRP2 affects the drug disposition. In the present article, we will summarize the physiological and pharmacological role of MRP2, particularly focusing on the factors affecting its transport function such as single nucleotide polymorphisms and/or the induction/down regulation of this transporter. Mutations found in patients suffering from the Dubin-Johnson syndrome, along with the amino acid residues which are involved in supporting the transport activity of MRP2, are also summarized.
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Affiliation(s)
- Hiroshi Suzuki
- School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
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36
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Gerk PM, Vore M. Regulation of expression of the multidrug resistance-associated protein 2 (MRP2) and its role in drug disposition. J Pharmacol Exp Ther 2002; 302:407-15. [PMID: 12130697 DOI: 10.1124/jpet.102.035014] [Citation(s) in RCA: 151] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The multidrug resistance protein 2 (MRP2; ABCC2) is an ATP-binding cassette transporter accepting a diverse range of substrates, including glutathione, glucuronide, and sulfate conjugates of many endo- and xenobiotics. MRP2 generally performs excretory or protective roles, and it is expressed on the apical domain of hepatocytes, enterocytes of the proximal small intestine, and proximal renal tubular cells, as well as in the brain and the placenta. MRP2 is regulated at several levels, including membrane retrieval and reinsertion, translation, and transcription. In addition to transport of conjugates, MRP2 transports cancer chemotherapeutics, uricosurics, antibiotics, leukotrienes, glutathione, toxins, and heavy metals. Several mutagenesis studies have described critical residues for substrate binding and various naturally occurring mutations that eliminate MRP2 expression or function. MRP2 is important clinically as it modulates the pharmacokinetics of many drugs, and its expression and activity are also altered by certain drugs and disease states.
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Affiliation(s)
- Phillip M Gerk
- Graduate Center for Toxicology, University of Kentucky, Room 306, Health Science Building, Lexington, KY 40536-0305, USA
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37
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Affiliation(s)
- Saul J Karpen
- Department of Pediatrics/GI and Nutrition, Texas Children's Liver Center, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA.
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38
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Abstract
Bile salts are the major organic solutes in bile and undergo extensive enterohepatic circulation. Hepatocellular bile salt uptake is mediated predominantly by the Na(+)-taurocholate cotransport proteins Ntcp (rodents) and NTCP (humans) and by the Na(+)-independent organic anion-transporting polypeptides Oatp1, Oatp2, and Oatp4 (rodents) and OATP-C (humans). After diffusion (bound by intracellular bile salt-binding proteins) to the canalicular membrane, monoanionic bile salts are secreted into bile canaliculi by the bile salt export pump Bsep (rodents) or BSEP (humans). Both belong to the ATP-binding cassette (ABC) transporter superfamily. Dianionic conjugated bile salts are secreted into bile by the multidrug-resistance-associated proteins Mrp2/MRP2. In bile ductules, a minor portion of protonated bile acids and monomeric bile salts are reabsorbed by non-ionic diffusion and the apical sodium-dependent bile salt transporter Asbt/ASBT, transported back into the periductular capillary plexus by Mrp3/MRP3 [and/or a truncated form of Asbt (tAsbt)], and subjected to cholehepatic shunting. The major portion of biliary bile salts is aggregated into mixed micelles and transported into the intestine, where they are reabsorbed by apical Oatp3, the apical sodium-dependent bile salt transporter (ASBT), cytosolic intestinal bile acid-binding protein (IBABP), and basolateral Mrp3/MRP3 and tAsbt. Transcriptional and posttranscriptional regulation of these enterohepatic bile salt transporters is closely related to the regulation of lipid and cholesterol homeostasis. Furthermore, defective expression and function of bile salt transporters have been recognized as important causes for various cholestatic liver diseases.
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Affiliation(s)
- Peter J Meier
- Division of Clinical Pharmacology and Toxicology, Department of Medicine, University Hospital, Zurich, 8091 Switzerland.
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39
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Abstract
Further insights into the molecular regulation of bile acid transport and metabolism have provided the basis for a better understanding of the pathogenesis of cholestatic liver diseases. Novel insights into the mechanisms of action of ursodeoxycholic acid should advance our understanding of the treatment of cholestatic liver diseases. Mutations of transporter genes can cause hereditary cholestatic syndromes in both infants and adults as well as cholesterol gallstone disease. Important studies have been published on the pathogenesis, clinical features, and treatment of primary biliary cirrhosis, drug-induced cholestasis, and cholestasis of pregnancy.
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Affiliation(s)
- Michael Trauner
- Division of Gastroenterology and Hepatology, Department of Internal Medicine, Karl-Franzens University, School of Medicine, Graz, Austria
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40
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Kullak-Ublick GA, Jung D, Hagenbuch B, Meier PJ. Organic anion transporting polypeptides, cholestasis, and nuclear receptors. Hepatology 2002; 35:732-4. [PMID: 11870396 DOI: 10.1053/jhep.2002.32027] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/07/2022]
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41
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Stanca C, Jung D, Meier PJ, Kullak-Ublick GA. Hepatocellular transport proteins and their role in liver disease. World J Gastroenterol 2001; 7:157-69. [PMID: 11819755 PMCID: PMC4723517 DOI: 10.3748/wjg.v7.i2.157] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Affiliation(s)
- C Stanca
- Division of Clinical Pharmacology and Toxicology, Department of Internal Medicine, University Hospital, CH-8091 Zurich/Switzerland
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