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Johnston CU, Kennedy CJ. Effects of the chemosensitizer verapamil on P-glycoprotein substrate efflux in rainbow trout hepatocytes. Comp Biochem Physiol C Toxicol Pharmacol 2024; 275:109763. [PMID: 37820937 DOI: 10.1016/j.cbpc.2023.109763] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Revised: 09/29/2023] [Accepted: 10/08/2023] [Indexed: 10/13/2023]
Abstract
The ATP-dependent membrane transporter P-glycoprotein (P-gp) is associated with resistance to a wide variety of chemical substrates, as well as the multi-drug resistance (MDR) phenotype in mammals. Less is known regarding P-gp's function and relevance in teleosts; this study expanded the range of known substrates and the inhibitory effects of a model chemosensitizer verapamil. The P-gp-mediated uptake and efflux dynamics of 5 known mammalian substrates (berberine, cortisol, doxorubicin, rhodamine 123 [R123], and vinorelbine) were examined in isolated rainbow trout (Oncorhynchus mykiss) hepatocytes with and without co-exposure to varying doses of verapamil. Initial substrate uptake rates (pmol/106 cells/min) varied widely and were in order: berberine (482 ± 94) > R123 (364 ± 67) > doxorubicin (158 ± 41) > cortisol (20.3 ± 5.9) > vinorelbine (15.3 ± 3.5). Initial efflux rates (pmol/106 cells/min) were highest in berberine (464 ± 110) > doxorubicin (341 ± 57) > R123 (106 ± 33) > cortisol (26.6 ± 6.1) > vinorelbine (9.0 ± 2.4). Transport of vinorelbine and R123 is verapamil sensitive, but verapamil had no effect on transport of berberine, cortisol, or doxorubicin. Cortisol and doxorubicin showed evidence of high P-gp affinity, thus displacing verapamil from their shared P-gp binding site. Cortisol, doxorubicin, R123, and vinorelbine transport by rainbow trout P-gp was confirmed, while berberine could not be confirmed or excluded as a substrate. Binding sites and affinities were similar between mammalian and trout P-gp for doxorubicin, R123, and vinorelbine, while fish P-gp had a higher affinity for cortisol than mammalian P-gp. This study demonstrated that the range of substrates, as well as binding sites and affinities, of fish P-gp are well-aligned with those in mammals.
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Affiliation(s)
- Christina U Johnston
- Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Christopher J Kennedy
- Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada.
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Kennedy CJ. P-glycoprotein induction and its energetic costs in rainbow trout (Oncorhynchus mykiss). FISH PHYSIOLOGY AND BIOCHEMISTRY 2021; 47:265-279. [PMID: 33405060 DOI: 10.1007/s10695-020-00911-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Accepted: 11/26/2020] [Indexed: 06/12/2023]
Abstract
Biological organisms are constantly challenged by xenobiotics and have evolved mechanisms to reduce, neutralize, or repair toxic outcomes. The various chemical defenses all utilize energy, but their specific costs and impacts on energy budgets are currently unknown. In this study, the energetic costs associated with the induction and substrate transport of the efflux transporter P-glycoprotein (P-gp [ABCB1, MDR1]) were examined in rainbow trout. An intraperitoneal injection of the P-gp inducer clotrimazole (0, 0.1, 1.0, and 10 mg/kg) increased P-gp activity (as measured by a competitive rhodamine 123 transport assay in hepatocytes) in a dose-dependent manner reaching a maximum induction of 2.8-fold. Maximum P-gp induction occurred at 50 h post-administration with the highest dose; significant induction of P-gp activity remained elevated over constitutive values until the last sampling time point (168 h). In vitro measurements of hepatocyte respiration indicated that basal P-gp activity transporting R123 as a substrate did not significantly increase respiration rates (range 18.0 to 23.2 ng O2/min/106 cells); however, following the induction of P-gp by clotrimazole and exposure to the P-gp substrate R123, respiration rates increased significantly (3.52-fold) over baseline values. Using whole animal respirometry, it was shown that respiration rates in fish exposed to R123 only or induced with clotrimazole were not different from controls (range 1.2 to 2.1 mg O2/kg/min); however, respiration rates were significantly increased in fish with induced P-gp levels and also exposed to R123. This work indicates that basal and induced levels of P-gp activity do not incur significant energetic costs to fish; however, upon induction of P-gp and concomitant substrate exposures, energetic costs can increase and could pose challenges to organisms facing limited energy resources.
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Affiliation(s)
- Christopher J Kennedy
- Department of Biological Sciences, Simon Fraser University, 8888 University Drive, Burnaby, BC, V5A 1S6, Canada.
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Love RC, Osachoff HL, Kennedy CJ. Short communication: Tissue-specific transcript expression of P-glycoprotein isoforms abcb1a and abcb1b in rainbow trout (Oncorhynchus mykiss) following induction with clotrimazole. Comp Biochem Physiol B Biochem Mol Biol 2020; 252:110538. [PMID: 33227421 DOI: 10.1016/j.cbpb.2020.110538] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Revised: 11/12/2020] [Accepted: 11/13/2020] [Indexed: 01/21/2023]
Abstract
P-glycoprotein (P-gp) plays a pivotal role in cellular defense, aimed at reducing xenobiotic accumulation. As a member of the ABC family of proteins, expression of this protein confers the multixenobiotic resistant (MXR) phenotype in aquatic organisms, including fish. To identify tissues protected by or contributing to the elimination of xenobiotics via P-gp, tissue-specific P-gp isoforms abcb1a and abcb1b transcript expression were measured in rainbow trout (Oncorhynchus mykiss). Tissues investigated included the proximal and distal intestines, liver, head kidney, gills, gonads, and 5 regions of the brain: olfactory lobe, cerebrum, optic lobe, cerebellum and medulla. Abcb1a transcript was more widely expressed across tissues and generally showed higher transcript expression than abcb1b. Deviation from this trend occurred in the gills, cerebrum and head kidney, where transcript levels were relatively equal between abcb1a and abcb1b. Intestinal tissues had greater abcb1a expression than abcb1b (3 orders of magnitude). Abcb1b was absent from liver tissue indicating that abcb1a is relied upon for hepatic defense. This study suggests that abcb1b acts to protect sensitive organs from compounds in the systemic circulation (brain and gonad), whereas abcb1a acts primarily in an elimination role in organs such as liver and intestine. To determine if P-gp induction alters transcript responses, the antifungal mammalian Pregnane-X-Receptor (PXR) agonist clotrimazole (CTZ) was used. CTZ-treated rainbow trout showed significantly increased abcb1b transcript expression in the optic lobe and distal intestine, providing evidence that trout PXR exhibits a similar substrate base as mammalian PXR, albeit selectively in regions of the brain and intestine.
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Affiliation(s)
- Ryan C Love
- Department of Biological Sciences, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia V5A 1S6, Canada
| | - Heather L Osachoff
- Department of Biological Sciences, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia V5A 1S6, Canada
| | - Christopher J Kennedy
- Department of Biological Sciences, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia V5A 1S6, Canada.
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Trowell JJ, Gobas FAPC, Moore MM, Kennedy CJ. Estimating the Bioconcentration Factors of Hydrophobic Organic Compounds from Biotransformation Rates Using Rainbow Trout Hepatocytes. ARCHIVES OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2018; 75:295-305. [PMID: 29550936 DOI: 10.1007/s00244-018-0508-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Accepted: 01/21/2018] [Indexed: 06/08/2023]
Abstract
Determining the biotransformation potential of commercial chemicals is critical for estimating their persistence in the aquatic environment. In vitro systems are becoming increasingly important as screening methods for assessing the potential for chemical metabolism. Depletion rate constants (kd) for several organic chemicals with high octanol-water partition coefficient (Kow) values (9-methylanthracene, benzo(a)pyrene, chrysene, and PCB-153) in rainbow trout hepatocytes were determined to estimate biotransformation rate constants (kMET) that were used in fish bioconcentration factor (BCF) models. Benzo[a]pyrene was rapidly biotransformed when incubated singly; however, its depletion rate constant (kd) declined 79% in a mixture of all four chemicals. Chrysene also exhibited significant biotransformation and its depletion rate constant declined by 50% in the mixture incubation. These data indicate that biotransformation rates determined using single chemicals may overestimate metabolism in environments containing chemical mixtures. Incubations with varying cell concentrations were used to determine whether cell concentration affected kd estimates. No statistically significant change in depletion rate constants were seen, possibly due to an increase in nonspecific binding of hydrophobic chemicals as cell density increased, decreasing overall biotransformation. A new model was used to estimate BCFs from kMET values calculated from empirically derived kd values. The inclusion of kMET in models resulted in significantly lower BCF values (compared kMET = 0). Modelled BCF values were consistent with empirically derived BCF values from the literature.
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Affiliation(s)
- Jennifer J Trowell
- Department of Biology, Simon Fraser University, 8888 University Drive, Burnaby, BC, V5A 1S6, Canada
| | - Frank A P C Gobas
- School of Resource and Environmental Management, Simon Fraser University, 8888 University Drive, Burnaby, BC, V5A 1S6, Canada
| | - Margo M Moore
- Department of Biology, Simon Fraser University, 8888 University Drive, Burnaby, BC, V5A 1S6, Canada
| | - Christopher J Kennedy
- Department of Biology, Simon Fraser University, 8888 University Drive, Burnaby, BC, V5A 1S6, Canada.
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Fay KA, Nabb DL, Mingoia RT, Bischof I, Nichols JW, Segner H, Johanning K, Han X. Determination of Metabolic Stability Using Cryopreserved Hepatocytes from Rainbow Trout (
Oncorhynchus mykiss
). ACTA ACUST UNITED AC 2015; 65:4.42.1-4.42.29. [DOI: 10.1002/0471140856.tx0442s65] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Kellie A. Fay
- ORD/NHEERL/Mid‐Continent Ecology Division, U.S. EPA Duluth Minnesota
| | - Diane L. Nabb
- DuPont Haskell Global Centers for Health and Environmental Sciences Newark Delaware
| | - Robert T. Mingoia
- DuPont Haskell Global Centers for Health and Environmental Sciences Newark Delaware
| | - Ina Bischof
- Centre for Fish and Wildlife Health, University of Bern Bern Switzerland
- Fraunhofer Institute for Molecular Biology and Applied Ecology Schmallenberg Germany
| | - John W. Nichols
- ORD/NHEERL/Mid‐Continent Ecology Division, U.S. EPA Duluth Minnesota
| | - Helmut Segner
- Centre for Fish and Wildlife Health, University of Bern Bern Switzerland
| | - Karla Johanning
- KJ Scientific LCC, Texas Life Sciences Collaboration Center Georgetown Texas
| | - Xing Han
- DuPont Haskell Global Centers for Health and Environmental Sciences Newark Delaware
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Uchea C, Owen SF, Chipman JK. Functional xenobiotic metabolism and efflux transporters in trout hepatocyte spheroid cultures. Toxicol Res (Camb) 2015; 4:494-507. [PMID: 25893091 PMCID: PMC4384106 DOI: 10.1039/c4tx00160e] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2014] [Accepted: 01/28/2015] [Indexed: 12/12/2022] Open
Abstract
Prediction of xenobiotic fate in fish is important for the regulatory assessment of chemicals under current legislation.
Prediction of xenobiotic fate in fish is important for the regulatory assessment of chemicals under current legislation. Trout hepatocyte spheroids are a promising in vitro model for this assessment. In this investigation, the gene expression and function for xenobiotic metabolism and cellular efflux were characterised. Using fluorescence, transport and real time PCR analysis, the expression and functionality of a variety of genes related to xenobiotic metabolism and drug efflux were assessed in a range of trout hepatocyte culture preparations. Significantly greater levels of expression of genes involved in xenobiotic metabolism and efflux were measured in spheroids (which have been shown to remain viable in excess of 30 days), compared to hepatocytes cultured using conventional suspension and monolayer culture techniques. A transient decline in the expression of genes related to both xenobiotic metabolism and transport was determined during spheroid development, with a subsequent recovery in older spheroids. The most mature spheroids also exhibited an expression profile most comparable to that reported in vivo. Functionality of efflux transporters in spheroids was also demonstrated using fluorescent markers and specific inhibitors. In conclusion, the more physiologically relevant architecture in spheroid cultures provides a high functional integrity in relation to xenobiotic metabolism and efflux. Together with the enhanced gene expression and longevity of the model, hepatocytes in spheroid culture may prove to be an accurate alternative model to study the mechanisms of these processes in fish liver and provide an assay to determine the bioaccumulation potential of environmental contaminants.
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Affiliation(s)
- Chibuzor Uchea
- University of Birmingham , School of Biosciences , Birmingham , B15 2TT , UK ; AstraZeneca , Alderley Park , Macclesfield , Cheshire , SK10 4TF , UK .
| | - Stewart F Owen
- AstraZeneca , Alderley Park , Macclesfield , Cheshire , SK10 4TF , UK .
| | - J Kevin Chipman
- University of Birmingham , School of Biosciences , Birmingham , B15 2TT , UK
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Luckenbach T, Fischer S, Sturm A. Current advances on ABC drug transporters in fish. Comp Biochem Physiol C Toxicol Pharmacol 2014; 165:28-52. [PMID: 24858718 DOI: 10.1016/j.cbpc.2014.05.002] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2013] [Revised: 05/13/2014] [Accepted: 05/14/2014] [Indexed: 01/14/2023]
Abstract
Most members of the large ATP-binding cassette (ABC) gene family are transporters involved in substrate translocation across biological membranes. In eukaryotes, ABC proteins functioning as drug transporters are located in the plasma membrane and mediate the cellular efflux of a wide range of organic chemicals, with some transporters also transporting certain metals. As the enhanced expression of ABC drug transporters can confer multidrug resistance (MDR) to cancers and multixenobiotic resistance (MXR) to organisms from polluted habitats, these ABC family members are also referred to as MDR or MXR proteins. In mammals, ABC drug transporters show predominant expression in tissues involved in excretion or constituting internal or external body boundaries, where they facilitate the excretion of chemicals and their metabolites, and limit chemical uptake and penetration into "sanctuary" sites of the body. Available knowledge about ABC proteins is still limited in teleost fish, a large vertebrate group of high ecological and economic importance. Using transport activity measurements and immunochemical approaches, early studies demonstrated similarities in the tissue distribution of ABC drug transporters between teleosts and mammals, suggesting conserved roles of the transporters in the biochemical defence against toxicants. Recently, the availability of teleost genome assemblies has stimulated studies of the ABC family in this taxon. This review summarises the current knowledge regarding the genetics, functional properties, physiological function, and ecotoxicological relevance of teleostean ABC transporters. The available literature is reviewed with emphasis on recent studies addressing the tissue distribution, substrate spectrum, regulation, physiological function and phylogenetic origin of teleostean ABC transporters.
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Affiliation(s)
- Till Luckenbach
- Department of Bioanalytical Ecotoxicology, UFZ-Helmholtz Centre for Environmental Research, 04318 Leipzig, Germany
| | - Stephan Fischer
- Department of Environmental Toxicology, Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland; Department of Environmental Systems Sciences, ETH Zürich, Institute of Biogeochemistry and Pollutant Dynamics, 8092 Zürich, Switzerland
| | - Armin Sturm
- Institute of Aquaculture, School of Natural Sciences, University of Stirling, Stirling FK9 4LA, Scotland, UK.
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Cole BJ, Hamdoun A, Epel D. Cost, effectiveness and environmental relevance of multidrug transporters in sea urchin embryos. ACTA ACUST UNITED AC 2013; 216:3896-905. [PMID: 23913944 DOI: 10.1242/jeb.090522] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
ATP-binding cassette transporters protect cells via efflux of xenobiotics and endogenous byproducts of detoxification. While the cost of this ATP-dependent extrusion is known at the molecular level, i.e. the ATP used for each efflux event, the overall cost to a cell or organism of operating this defense is unclear, especially as the cost of efflux changes depending on environmental conditions. During prolonged exposure to xenobiotics, multidrug transporter activity could be costly and ineffective because effluxed substrate molecules are not modified in the process and could thus undergo repeated cycles of efflux and re-entry. Here we use embryos of the purple sea urchin, Strongylocentrotus purpuratus, as a model to determine transport costs and benefits under environmentally relevant xenobiotic concentrations. Strikingly, our results show that efflux transporter activity costs less than 0.2% of total ATP usage, as a proportion of oxygen consumption. The benefits of transport, defined as the reduction in substrate accumulation due to transporter activity, depended largely, but not entirely, on the rate of passive flux of each substrate across the plasma membrane. One of the substrates tested exhibited rapid membrane permeation coupled with high rates of efflux, thus inducing rapid and futile cycles of efflux followed by re-entry of the substrate. This combination significantly reduced transporter effectiveness as a defense and increased costs even at relatively low substrate concentrations. Despite these effects with certain substrates, our results show that efflux transporters are a remarkably effective and low-cost first line of defense against exposure to environmentally relevant concentrations of xenobiotics.
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Affiliation(s)
- Bryan J Cole
- Bodega Marine Laboratory, University of California Davis, Bodega Bay, CA 94923, USA
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Sotka EE, Forbey J, Horn M, Poore AGB, Raubenheimer D, Whalen KE. The emerging role of pharmacology in understanding consumer–prey interactions in marine and freshwater systems. Integr Comp Biol 2009; 49:291-313. [DOI: 10.1093/icb/icp049] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
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