1
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Targeting breast cancer resistance protein (BCRP/ABCG2): Functional inhibitors and expression modulators. Eur J Med Chem 2022; 237:114346. [DOI: 10.1016/j.ejmech.2022.114346] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 03/15/2022] [Accepted: 04/01/2022] [Indexed: 12/16/2022]
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2
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Zaborowska M, Dziubak D, Fontaine P, Matyszewska D. Influence of lipophilicity of anthracyclines on the interactions with cholesterol in the model cell membranes - Langmuir monolayer and SEIRAS studies. Colloids Surf B Biointerfaces 2021; 211:112297. [PMID: 34953365 DOI: 10.1016/j.colsurfb.2021.112297] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Revised: 12/11/2021] [Accepted: 12/15/2021] [Indexed: 10/19/2022]
Abstract
The interactions of anthracyclines with biological membranes strongly depend on the drug lipophilicity, which might also determine the specific affinity to cholesterol molecules. Therefore, in this work we show the studies concerning the effect of two selected anthracyclines, daunorubicin (DNR) and idarubicin (IDA) on simple models of healthy (DMPC:Chol 7:3) and cancer cells membranes with increased level of cholesterol (DMPC:Chol 3:7) as well as pure cholesterol monolayers prepared at the air-water interface and supported on gold surface. It has been shown that more lipophilic IDA is able to penetrate cholesterol monolayers more effectively than DNR due to the formation of IDA-cholesterol arrangements at the interface, as proved by the thermodynamic analysis of compression-expansion cycles. The increased interactions of IDA were also confirmed by the time measurements of pre-compressed monolayers exposed to drug solutions as well as grazing incidence X-ray diffraction studies demonstrating differences in the 2D organization of cholesterol monolayers. Langmuir studies of mixed DMPC:Chol membranes revealed the reorganization of molecules in the cancer cell models at the air-water interface at higher surface pressures due to the removal of DNR, while increased affinity of IDA towards cholesterol allowed this drug to penetrate the layer more efficiently without its removal. The SEIRAS spectra obtained for supported DMPC:Chol bilayers proved that IDA locates both in the ester group and in the acyl chain region of the bilayer, while DNR does not penetrate the membranes as deeply as IDA. The increased penetration of the mixed phospholipid layers by idarubicin might be attributed to the higher lipophilicity caused by the lack of methoxy group and resulting in a specific affinity towards cholesterol.
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Affiliation(s)
| | - Damian Dziubak
- Faculty of Chemistry, Biological and Chemical Research Centre, University of Warsaw, Żwirki i Wigury 101, 02089 Warsaw, Poland
| | - Philippe Fontaine
- Synchrotron Soleil, L'Orme des Merisiers, Saint Aubin, BP 48, 91192 Gif-sur-Yvette Cedex, France
| | - Dorota Matyszewska
- Faculty of Chemistry, Biological and Chemical Research Centre, University of Warsaw, Żwirki i Wigury 101, 02089 Warsaw, Poland
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3
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Lee WK, Maaß M, Quach A, Poscic N, Prangley H, Pallott EC, Kim JL, Pierce JS, Ogretmen B, Futerman AH, Thévenod F. Dependence of ABCB1 transporter expression and function on distinct sphingolipids generated by ceramide synthases-2 and -6 in chemoresistant renal cancer. J Biol Chem 2021; 298:101492. [PMID: 34915026 PMCID: PMC8804196 DOI: 10.1016/j.jbc.2021.101492] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Accepted: 12/07/2021] [Indexed: 11/18/2022] Open
Abstract
Oncogenic multidrug resistance is commonly intrinsic to renal cancer based on the physiological expression of detoxification transporters, particularly ABCB1, thus hampering chemotherapy. ABCB1 activity is directly dependent on its lipid microenvironment, localizing to cholesterol- and sphingomyelin (SM)-rich domains. As ceramides are the sole source for SMs, we hypothesized that ceramide synthase (CerS)-derived ceramides regulate ABCB1 activity. Using data from RNA-Seq databases, we found that patient kidney tumors exhibited increased CerS2 mRNA, which was inversely correlated with CerS6 mRNA in ABCB1+ clear cell carcinomas. Endogenous elevated CerS2 and lower CerS5/6 mRNA and protein resulted in disproportionately higher CerS2 to CerS5/6 activities (approximately twofold) in chemoresistant ABCB1high (A498, Caki-1) compared with chemosensitive ABCB1low (ACHN, normal human proximal convoluted tubule cell) cells. In addition, lipidomics analyses by HPLC–MS/MS showed bias toward CerS2-associated C20:0/C20:1-ceramides compared with CerS5/6-associated C14:0/C16:0-ceramides (2:1). SMs were similarly altered. We demonstrated that chemoresistance to doxorubicin in ABCB1high cells was partially reversed by inhibitors of de novo ceramide synthesis (l-cycloserine) and CerS (fumonisin B1) in cell viability assays. Downregulation of CerS2/6, but not CerS5, attenuated ABCB1 mRNA, protein, plasma membrane localization, rhodamine 123+ efflux transport activity, and doxorubicin resistance. Similar findings were observed with catalytically inactive CerS6-H212A. Furthermore, CerS6-targeting siRNA shifted ceramide and SM composition to ultra long-chain species (C22–C26). Inhibitors of endoplasmic reticulum–associated degradation (eeyarestatin I) and the proteasome (MG132, bortezomib) prevented ABCB1 loss induced by CerS2/6 downregulation. We conclude that a critical balance in ceramide/SM species is prerequisite to ABCB1 expression and functionalization, which could be targeted to reverse multidrug resistance in renal cancers.
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Affiliation(s)
- Wing-Kee Lee
- Institute for Physiology, Pathophysiology and Toxicology, ZBAF, Witten/Herdecke University, Germany; Physiology & Pathophysiology of Cells and Membranes, Medical School OWL, Bielefeld University, Germany.
| | - Michelle Maaß
- Institute for Physiology, Pathophysiology and Toxicology, ZBAF, Witten/Herdecke University, Germany
| | - Amy Quach
- Institute for Physiology, Pathophysiology and Toxicology, ZBAF, Witten/Herdecke University, Germany; Faculty of Life Sciences, University of Manchester, UK
| | - Nataliya Poscic
- Institute for Physiology, Pathophysiology and Toxicology, ZBAF, Witten/Herdecke University, Germany
| | - Holly Prangley
- Institute for Physiology, Pathophysiology and Toxicology, ZBAF, Witten/Herdecke University, Germany; Faculty of Life Sciences, University of Manchester, UK
| | - Erin-Claire Pallott
- Institute for Physiology, Pathophysiology and Toxicology, ZBAF, Witten/Herdecke University, Germany; Faculty of Life Sciences, University of Manchester, UK
| | - Jiyoon L Kim
- Department of Biomolecular Sciences, Weizmann Institute of Science, Israel
| | - Jason S Pierce
- Lipidomics Shared Resource, Medical University of South Carolina, USA
| | - Besim Ogretmen
- Lipidomics Shared Resource, Medical University of South Carolina, USA; Department of Biochemistry and Molecular Biology, Medical University of South Carolina, USA
| | - Anthony H Futerman
- Department of Biomolecular Sciences, Weizmann Institute of Science, Israel
| | - Frank Thévenod
- Institute for Physiology, Pathophysiology and Toxicology, ZBAF, Witten/Herdecke University, Germany
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4
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Fedotcheva TA, Fedotcheva NI, Shimanovsky NL. Progestins as Anticancer Drugs and Chemosensitizers, New Targets and Applications. Pharmaceutics 2021; 13:pharmaceutics13101616. [PMID: 34683909 PMCID: PMC8540053 DOI: 10.3390/pharmaceutics13101616] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2021] [Revised: 09/22/2021] [Accepted: 10/01/2021] [Indexed: 01/13/2023] Open
Abstract
Progesterone and its synthetic analogues, progestins, participate in the regulation of cell differentiation, proliferation and cell cycle progression. Progestins are usually applied for contraception, maintenance of pregnancy, and hormone replacement therapy. Recently, their effectiveness in the treatment of hormone-sensitive tumors was revealed. According to current data, the anticancer activity of progestins is mainly mediated by their cytotoxic and chemosensitizing influence on different cancer cells. In connection with the detection of previously unknown targets of the progestin action, which include the membrane-associated progesterone receptor (PR), non-specific transporters related to the multidrug resistance (MDR) and mitochondrial permeability transition pore (MPTP), and checkpoints of different signaling pathways, new aspects of their application have emerged. It is likely that the favorable influence of progestins is predominantly associated with the modulation of expression and activity of MDR-related proteins, the inhibition of survival signaling pathways, especially TGF-β and Wnt/β-catenin pathways, which activate the proliferation and promote MDR in cancer cells, and the facilitation of mitochondrial-dependent apoptosis. Biological effects of progestins are mediated by the inhibition of these signaling pathways, as well as the direct interaction with the nucleotide-binding domain of ABC-transporters and mitochondrial adenylate translocase as an MPTP component. In these ways, progestins can restore the proliferative balance, the ability for apoptosis, and chemosensitivity to drugs, which is especially important for hormone-dependent tumors associated with estrogen stress, epithelial-to-mesenchymal transition, and drug resistance.
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Affiliation(s)
- Tatiana A. Fedotcheva
- Science Research Laboratory of Molecular Pharmacology, Medical Biological Faculty, Pirogov Russian National Research Medical University, Ministry of Health of the Russian Federation, Ostrovityanova St. 1, 117997 Moscow, Russia;
- Correspondence: ; Tel.: +7-916-935-31-96
| | - Nadezhda I. Fedotcheva
- Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Institutskaya str., 3, Pushchino, 142290 Moscow, Russia;
| | - Nikolai L. Shimanovsky
- Science Research Laboratory of Molecular Pharmacology, Medical Biological Faculty, Pirogov Russian National Research Medical University, Ministry of Health of the Russian Federation, Ostrovityanova St. 1, 117997 Moscow, Russia;
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5
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Reker D, Shi Y, Kirtane AR, Hess K, Zhong GJ, Crane E, Lin CH, Langer R, Traverso G. Machine Learning Uncovers Food- and Excipient-Drug Interactions. Cell Rep 2021; 30:3710-3716.e4. [PMID: 32187543 PMCID: PMC7179333 DOI: 10.1016/j.celrep.2020.02.094] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Revised: 01/06/2020] [Accepted: 02/26/2020] [Indexed: 12/15/2022] Open
Abstract
Inactive ingredients and generally recognized as safe compounds are regarded by the US Food and Drug Administration (FDA) as benign for human consumption within specified dose ranges, but a growing body of research has revealed that many inactive ingredients might have unknown biological effects at these concentrations and might alter treatment outcomes. To speed up such discoveries, we apply state-of-the-art machine learning to delineate currently unknown biological effects of inactive ingredients—focusing on P-glycoprotein (P-gp) and uridine diphosphate-glucuronosyltransferase-2B7 (UGT2B7), two proteins that impact the pharmacokinetics of approximately 20% of FDA-approved drugs. Our platform identifies vitamin A palmitate and abietic acid as inhibitors of P-gp and UGT2B7, respectively; in silico, in vitro, ex vivo, and in vivo validations support these interactions. Our predictive framework can elucidate biological effects of commonly consumed chemical matter with implications on food-and excipient-drug interactions and functional drug formulation development. Reker et al. use machine learning to identify biological activities of food and drug additives. Validation confirms vitamin A palmitate as an inhibitor of P-glycoprotein transport and abietic acid as an inhibitor of UGT2b7 metabolism. Such associations have important implications as food-or excipient-drug interactions.
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Affiliation(s)
- Daniel Reker
- David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Division of Gastroenterology, Hepatology and Endoscopy, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA; MIT-IBM Watson AI Lab, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Yunhua Shi
- David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Ameya R Kirtane
- David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Kaitlyn Hess
- David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Grace J Zhong
- David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Evan Crane
- David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Chih-Hsin Lin
- David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Robert Langer
- David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; MIT-IBM Watson AI Lab, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Giovanni Traverso
- David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Division of Gastroenterology, Hepatology and Endoscopy, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA; MIT-IBM Watson AI Lab, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
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6
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Clouser AF, Alam YH, Atkins WM. Cholesterol Asymmetrically Modulates the Conformational Ensemble of the Nucleotide-Binding Domains of P-Glycoprotein in Lipid Nanodiscs. Biochemistry 2020; 60:85-94. [PMID: 33350827 DOI: 10.1021/acs.biochem.0c00824] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
P-Glycoprotein (P-gp) is an ATP-dependent efflux pump that clears a wide variety of drugs and toxins from cells. P-gp undergoes large-scale structural changes and demonstrates conformational heterogeneity even within a single catalytic or drug-bound state, although the role of heterogeneity remains unclear. P-gp is found in a variety of cell types that vary in lipid composition, which modulates its activity. An understanding of structural or dynamic changes due to the lipid environment is lacking. We aimed to determine the effects of cholesterol in a membrane on the conformational behavior of P-gp in lipid nanodiscs. The presence of cholesterol stimulates ATP hydrolysis and alters lipid order and fluidity. Hydrogen/deuterium exchange mass spectrometry demonstrates that cholesterol in the membrane induces asymmetric, long-range changes in the distributions and exchange kinetics of conformations of the nucleotide-binding domains, correlating the effects of lipid composition on activity with specific changes in the P-gp conformational landscape.
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Affiliation(s)
- Amanda F Clouser
- Department of Medicinal Chemistry, University of Washington, Seattle, Washington 98195-7610, United States
| | - Yasmine H Alam
- Department of Medicinal Chemistry, University of Washington, Seattle, Washington 98195-7610, United States.,Department of Biological Sciences, MARC Program, California State University, Fullerton, California 92834-6850, United States
| | - William M Atkins
- Department of Medicinal Chemistry, University of Washington, Seattle, Washington 98195-7610, United States
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7
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Nicklisch SC, Hamdoun A. Disruption of small molecule transporter systems by Transporter-Interfering Chemicals (TICs). FEBS Lett 2020; 594:4158-4185. [PMID: 33222203 PMCID: PMC8112642 DOI: 10.1002/1873-3468.14005] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2020] [Revised: 11/17/2020] [Accepted: 11/17/2020] [Indexed: 12/25/2022]
Abstract
Small molecule transporters (SMTs) in the ABC and SLC families are important players in disposition of diverse endo- and xenobiotics. Interactions of environmental chemicals with these transporters were first postulated in the 1990s, and since validated in numerous in vitro and in vivo scenarios. Recent results on the co-crystal structure of ABCB1 with the flame-retardant BDE-100 demonstrate that a diverse range of man-made and natural toxic molecules, hereafter termed transporter-interfering chemicals (TICs), can directly bind to SMTs and interfere with their function. TIC-binding modes mimic those of substrates, inhibitors, modulators, inducers, and possibly stimulants through direct and allosteric mechanisms. Similarly, the effects could directly or indirectly agonize, antagonize or perhaps even prime the SMT system to alter transport function. Importantly, TICs are distinguished from drugs and pharmaceuticals that interact with transporters in that exposure is unintended and inherently variant. Here, we review the molecular mechanisms of environmental chemical interaction with SMTs, the methodological considerations for their evaluation, and the future directions for TIC discovery.
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Affiliation(s)
- Sascha C.T. Nicklisch
- Department of Environmental Toxicology, University of California, Davis, Davis, CA 95616
| | - Amro Hamdoun
- Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92093-0202
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8
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Thangapandian S, Kapoor K, Tajkhorshid E. Probing cholesterol binding and translocation in P-glycoprotein. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2020; 1862:183090. [PMID: 31676371 PMCID: PMC6934093 DOI: 10.1016/j.bbamem.2019.183090] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Revised: 09/15/2019] [Accepted: 09/17/2019] [Indexed: 01/01/2023]
Abstract
P-glycoprotein (Pgp) is a biomedically important member of the ABC transporter superfamily that mediates multidrug resistance in various cancer types. Substrate binding and transport in Pgp are modulated by the presence of cholesterol in the membrane. Structural information on cholesterol binding sites and mechanistic details of its redistribution are, however, largely unknown. In this study, a set of 40 independent molecular dynamics (MD) simulations of Pgp embedded in cholesterol-rich lipid bilayers are reported, totaling 8 μs, enabling extensive sampling of cholesterol-protein interactions in Pgp. Clustering analyses of the ensemble of cholesterol molecules (∼5740) sampled around Pgp in these simulations reveal specific and asymmetric cholesterol-binding regions formed by the transmembrane (TM) helices TM1-6 and TM8. Notably, not all the putative cholesterol binding sites identified by MD can be predicted by the primary sequence based cholesterol-recognition amino acid consensus (CRAC) or inverted CRAC (CARC) motifs, an observation that we attribute to inadequacy of these motifs to account for binding sites formed by remote amino acids in the sequence that can still be spatially adjacent to each other. Binding of cholesterol to Pgp occurs more frequently through its rough β-face formed by the two protruding methyl groups, whereas the opposite smooth α-face prefers packing alongside the membrane lipids. One full and two partial cholesterol flipping events between the two leaflets of the bilayer mediated by the surface of Pgp are also captured in these simulations. All flipping events are observed in a region formed by helices TM1, TM2, and TM11, featuring two full and two partial CRAC/CARC motifs, with Tyr49 and Tyr126 identified as key residues interacting with cholesterol during this event. Our study is the first to report direct observation of unconventional cholesterol translocation on the surface of Pgp, providing a secondary transport model for the known flippase activity of ABC exporters of cholesterol. This article is part of a Special Issue entitled: Molecular biophysics of membranes and membrane proteins.
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Affiliation(s)
- Sundar Thangapandian
- NIH Center for Molecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology, Department of Biochemistry, Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Karan Kapoor
- NIH Center for Molecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology, Department of Biochemistry, Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Emad Tajkhorshid
- NIH Center for Molecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology, Department of Biochemistry, Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
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9
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Bourassa P, Tremblay C, Schneider JA, Bennett DA, Calon F. Beta-amyloid pathology in human brain microvessel extracts from the parietal cortex: relation with cerebral amyloid angiopathy and Alzheimer's disease. Acta Neuropathol 2019; 137:801-823. [PMID: 30729296 DOI: 10.1007/s00401-019-01967-4] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Revised: 01/24/2019] [Accepted: 01/24/2019] [Indexed: 01/13/2023]
Abstract
Several pieces of evidence suggest that blood-brain barrier (BBB) dysfunction is implicated in the pathophysiology of Alzheimer's disease (AD), exemplified by the frequent occurrence of cerebral amyloid angiopathy (CAA) and the defective clearance of Aβ peptides. However, the specific role of brain microvascular cells in these anomalies remains elusive. In this study, we validated by Western, ELISA and immunofluorescence analyses a procedure to generate microvasculature-enriched fractions from frozen samples of human cerebral cortex. We then investigated Aβ and proteins involved in its clearance or production in microvessel extracts generated from the parietal cortex of 60 volunteers in the Religious Orders Study. Volunteers were categorized as AD (n = 38) or controls (n = 22) based on the ABC scoring method presented in the revised guidelines for the neuropathological diagnosis of AD. Higher ELISA-determined concentrations of vascular Aβ40 and Aβ42 were found in persons with a neuropathological diagnosis of AD, in apoE4 carriers and in participants with advanced parenchymal CAA, compared to respective age-matched controls. Vascular levels of two proteins involved in Aβ clearance, ABCB1 and neprilysin, were lower in persons with AD and positively correlated with cognitive function, while being inversely correlated to vascular Aβ40. In contrast, BACE1, a protein necessary for Aβ production, was increased in individuals with AD and in apoE4 carriers, negatively correlated to cognitive function and positively correlated to Aβ40 in microvessel extracts. The present report indicates that concentrating microvessels from frozen human brain samples facilitates the quantitative biochemical analysis of cerebrovascular dysfunction in CNS disorders. Data generated overall show that microvessels extracted from individuals with parenchymal CAA-AD contained more Aβ and BACE1 and less ABCB1 and neprilysin, evidencing a pattern of dysfunction in brain microvascular cells contributing to CAA and AD pathology and symptoms.
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Affiliation(s)
- Philippe Bourassa
- Faculté de pharmacie, Université Laval, Quebec, QC, Canada
- Axe Neurosciences, Centre de recherche du CHU de Québec-Université Laval, 2705, Boulevard Laurier, Room T2-67, Quebec, QC, G1V 4G2, Canada
| | - Cyntia Tremblay
- Axe Neurosciences, Centre de recherche du CHU de Québec-Université Laval, 2705, Boulevard Laurier, Room T2-67, Quebec, QC, G1V 4G2, Canada
| | - Julie A Schneider
- Rush Alzheimer's Disease Center, Rush University Medical Center, Chicago, IL, USA
| | - David A Bennett
- Rush Alzheimer's Disease Center, Rush University Medical Center, Chicago, IL, USA
| | - Frédéric Calon
- Faculté de pharmacie, Université Laval, Quebec, QC, Canada.
- Axe Neurosciences, Centre de recherche du CHU de Québec-Université Laval, 2705, Boulevard Laurier, Room T2-67, Quebec, QC, G1V 4G2, Canada.
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Naren D, Wu J, Gong Y, Yan T, Wang K, Xu W, Yang X, Shi F, Shi R. Niemann-Pick disease type C1(NPC1) is involved in resistance against imatinib in the imatinib-resistant Ph+ acute lymphoblastic leukemia cell line SUP-B15/RI. Leuk Res 2016; 42:59-67. [PMID: 26818574 DOI: 10.1016/j.leukres.2016.01.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Revised: 01/12/2016] [Accepted: 01/13/2016] [Indexed: 02/05/2023]
Abstract
Niemann-Pick disease type C1 (NPC1) is involved in cholesterol trafficking and may normally function as a transmembrane efflux pump. Previous studies showed that its dysfunction can lead to cholesterol and daunorubicin accumulation in the cytoplasmic endosomal/lysosomal system, lead to Niemann-Pick disease and resistance to anticancer drugs. In the present study, NPC1 was shown by microarray analysis to be more highly expressed in the Ph+ acute lymphoblastic leukemia cell line SUP-B15/RI, an imatinib-resistant variant of SUP-B15/S cells without bcr-abl gene mutation established in our lab. Further investigation revealed a defect in the functional capacity of the NPC1 protein demonstrated by filipin staining accompanied by a lower intracellular imatinib mesylate(IM) concentration by high-performance liquid chromatography in SUP-B15/RI compared with SUP-B15/S cells. Furthermore, U18666A, an inhibitor of NPC1 function, was used to block cholesterol trafficking to imitate the NPC1 defect in SUP-B15/S cells, leading to higher NPC1 expression, stronger filipin fluorescence, lower intracellular IM concentrations and greater resistance against IM. Samples from non-mutated relapsed Ph+ ALL patients also showed higher NPC1 expression compared with IM-sensitive patients. Our experiment may reveal a new mechanism of IM resistance in Ph+ ALL.
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Affiliation(s)
- Duolan Naren
- Department of Hematology, West China Hospital, Sichuan University, 610041, PR China
| | - Jiahui Wu
- Department of Hematology, West China Hospital, Sichuan University, 610041, PR China
| | - Yuping Gong
- Department of Hematology, West China Hospital, Sichuan University, 610041, PR China.
| | - Tianyou Yan
- Department of Hematology, West China Hospital, Sichuan University, 610041, PR China
| | - Ke Wang
- Joint Laboratory of Reproductive Medicine, SCU-CUHK, Key Laboratory of Birth Defects and Related Diseases of Women and Children, Ministry of Education, Sichuan University, West China Second University Hospital, Sichuan University, Chengdu 610041, PR China; Department of Obstetric and Gynecologic Diseases, West China Second University Hospital, Sichuan University, Chengdu 610041, PR China
| | - Wenming Xu
- Joint Laboratory of Reproductive Medicine, SCU-CUHK, Key Laboratory of Birth Defects and Related Diseases of Women and Children, Ministry of Education, Sichuan University, West China Second University Hospital, Sichuan University, Chengdu 610041, PR China; Department of Obstetric and Gynecologic Diseases, West China Second University Hospital, Sichuan University, Chengdu 610041, PR China
| | - Xi Yang
- Department of Hematology, West China Hospital, Sichuan University, 610041, PR China
| | - Fangfang Shi
- Department of Hematology, West China Hospital, Sichuan University, 610041, PR China
| | - Rui Shi
- Department of Hematology, West China Hospital, Sichuan University, 610041, PR China
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11
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Celestino AT, Levy D, Maria Ruiz JL, Bydlowski SP. ABCB1, ABCC1, and LRP gene expressions are altered by LDL, HDL, and serum deprivation in a human doxorubicin-resistant uterine sarcoma cell line. Biochem Biophys Res Commun 2015; 457:664-8. [DOI: 10.1016/j.bbrc.2015.01.045] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2014] [Accepted: 01/10/2015] [Indexed: 12/22/2022]
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12
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Sharom FJ. Complex Interplay between the P-Glycoprotein Multidrug Efflux Pump and the Membrane: Its Role in Modulating Protein Function. Front Oncol 2014; 4:41. [PMID: 24624364 PMCID: PMC3939933 DOI: 10.3389/fonc.2014.00041] [Citation(s) in RCA: 184] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2013] [Accepted: 02/17/2014] [Indexed: 11/16/2022] Open
Abstract
Multidrug resistance in cancer is linked to expression of the P-glycoprotein multidrug transporter (Pgp, ABCB1), which exports many structurally diverse compounds from cells. Substrates first partition into the bilayer and then interact with a large flexible binding pocket within the transporter's transmembrane regions. Pgp has been described as a hydrophobic vacuum cleaner or an outwardly directed drug/lipid flippase. Recent X-ray crystal structures have shed some light on the nature of the drug-binding pocket and suggested routes by which substrates can enter it from the membrane. Detergents have profound effects on Pgp function, and several appear to be substrates. Biochemical and biophysical studies in vitro, some using purified reconstituted protein, have explored the effects of the membrane environment. They have demonstrated that Pgp is involved in a complex relationship with its lipid environment, which modulates the behavior of its substrates, as well as various functions of the protein, including ATP hydrolysis, drug binding, and drug transport. Membrane lipid composition and fluidity, phospholipid headgroup and acyl chain length all influence Pgp function. Recent studies focusing on thermodynamics and kinetics have revealed some important principles governing Pgp-lipid and substrate-lipid interactions, and how these affect drug-binding and transport. In some cells, Pgp is associated with cholesterol-rich microdomains, which may modulate its functions. The relationship between Pgp and cholesterol remains an open question; however, it clearly affects several aspects of its function in addition to substrate-membrane partitioning. The action of Pgp modulators appears to depend on their membrane permeability, and membrane fluidizers and surfactants reverse drug resistance, likely via an indirect mechanism. A detailed understanding of how the membrane affects Pgp substrates and Pgp's catalytic cycle may lead to new strategies to combat clinical drug resistance.
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Affiliation(s)
- Frances Jane Sharom
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, Canada
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Zhang Y, Hu Y, Feng Y, Kodithuwakku ND, Fang W, Li Y, Huang W. The inhibitory and combinative mechanism of HZ08 with P-glycoprotein expressed on the membrane of Caco-2 cell line. Toxicol Appl Pharmacol 2014; 274:232-9. [DOI: 10.1016/j.taap.2013.11.019] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2013] [Revised: 10/29/2013] [Accepted: 11/23/2013] [Indexed: 01/15/2023]
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Abstract
ABC (ATP-binding cassette) proteins actively transport a wide variety of substrates, including peptides, amino acids, sugars, metals, drugs, vitamins and lipids, across extracellular and intracellular membranes. Of the 49 hum an ABC proteins, a significant number are known to mediate the extrusion of lipids from membranes or the flipping of membrane lipids across the bilayer to generate and maintain membrane lipid asymmetry. Typical lipid substrates include phospholipids, sterols, sphingolipids, bile acids and related lipid conjugates. Members of the ABCA subfamily of ABC transporters and other ABC proteins such as ABCB4, ABCG1 and ABCG5/8 implicated in lipid transport play important roles in diverse biological processes such as cell signalling, membrane lipid asymmetry, removal of potentially toxic compounds and metabolites, and apoptosis. The importance of these ABC lipid transporters in cell physiology is evident from the finding that mutations in the genes encoding many of these proteins are responsible for severe inherited diseases. For example, mutations in ABCA1 cause Tangier disease associated with defective efflux of cholesterol and phosphatidylcholine from the plasma membrane to the lipid acceptor protein apoA1 (apolipoprotein AI), mutations in ABCA3 cause neonatal surfactant deficiency associated with a loss in secretion of the lipid pulmonary surfactants from lungs of newborns, mutations in ABCA4 cause Stargardt macular degeneration, a retinal degenerative disease linked to the reduced clearance of retinoid compounds from photoreceptor cells, mutations in ABCA12 cause harlequin and lamellar ichthyosis, skin diseases associated with defective lipid trafficking in keratinocytes, and mutations in ABCB4 and ABCG5/ABCG8 are responsible for progressive intrafamilial hepatic disease and sitosterolaemia associated with defective phospholipid and sterol transport respectively. This chapter highlights the involvement of various mammalian ABC transporters in lipid transport in the context of their role in cell signalling, cellular homoeostasis, apoptosis and inherited disorders.
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Aurade RM, Jayalakshmi SK, Udikeri SS, Sreeramulu K. Modulation of P-glycoprotein ATPase of Helicoverpa armigera by cholesterol: effects on ATPase activity and interaction of insecticides. ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2012; 79:47-60. [PMID: 23589220 DOI: 10.1002/arch.21004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Purified P-glycoprotein ATPase from Helicoverpa armigera (Ha-Pgp), reconstituted in proteoliposomes composed of phospholipids and cholesterol, shows higher ATPase activity in the presence of cholesterol than in its absence. The Ha-Pgp ATPase activity was increased 30-40% with cholesterol. The KM for ATP was found to be 1 and 0.8 mM in the absence and presence of cholesterol, respectively. The insecticide-stimulated Ha-Pgp ATPase activity was increased by 10-20% for all the insecticides in the reconstituted proteoliposomes containing cholesterol compared to those with no cholesterol. The effects of cholesterol on KM and Vmax values of insecticide-stimulated Ha-Pgp ATPase activity were unrelated to the size of the insecticide. Ha-Pgp tryptophan fluorescence displayed a red shift of 3 and 8 nm in emission spectra upon binding of insecticides. Cholesterol enhances the interaction of insecticides with Ha-Pgp. Kd values of different insecticides for binding to Ha-Pgp were found to be lower in the presence of cholesterol in the proteoliposomes compared to its absence. Results suggest that cholesterol plays a role in the recognition and interaction of insecticides by modulating Ha-Pgp ATPase and may be involved in efflux of insecticides from cells by the transporter.
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Affiliation(s)
- Ravindra M Aurade
- Department of Biochemistry, Gulbarga University, Gulbarga, Karnataka, India
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16
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Dolghih E, Bryant C, Renslo AR, Jacobson MP. Predicting binding to p-glycoprotein by flexible receptor docking. PLoS Comput Biol 2011; 7:e1002083. [PMID: 21731480 PMCID: PMC3121697 DOI: 10.1371/journal.pcbi.1002083] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2011] [Accepted: 04/22/2011] [Indexed: 01/07/2023] Open
Abstract
P-glycoprotein (P-gp) is an ATP-dependent transport protein that is selectively expressed at entry points of xenobiotics where, acting as an efflux pump, it prevents their entering sensitive organs. The protein also plays a key role in the absorption and blood-brain barrier penetration of many drugs, while its overexpression in cancer cells has been linked to multidrug resistance in tumors. The recent publication of the mouse P-gp crystal structure revealed a large and hydrophobic binding cavity with no clearly defined sub-sites that supports an “induced-fit” ligand binding model. We employed flexible receptor docking to develop a new prediction algorithm for P-gp binding specificity. We tested the ability of this method to differentiate between binders and nonbinders of P-gp using consistently measured experimental data from P-gp efflux and calcein-inhibition assays. We also subjected the model to a blind test on a series of peptidic cysteine protease inhibitors, confirming the ability to predict compounds more likely to be P-gp substrates. Finally, we used the method to predict cellular metabolites that may be P-gp substrates. Overall, our results suggest that many P-gp substrates bind deeper in the cavity than the cyclic peptide in the crystal structure and that specificity in P-gp is better understood in terms of physicochemical properties of the ligands (and the binding site), rather than being defined by specific sub-sites. With many drugs failing in the preclinical stages of drug discovery due to undesirable ADMETox (absorption, distribution, metabolism, excretion and toxicity) properties, improvement of these properties early on in the process, alongside the optimization of the compound activity, is emerging as a new focus in the pharmaceutical field. One of the key players affecting pharmacokinetic profiles of many clinically relevant compounds is an active efflux transporter, P-glycoprotein. Expressed predominantly at various physiological barriers, it can influence drug absorption (intestinal epithelium, colon), drug elimination (kidney proximal tubules) and drug penetration of the blood-brain barrier (endothelial brain cells). Moreover, its increased expression in cancer cells has been linked to resistance to multiple drugs in tumors. In this study we describe a computational approach that allows prediction of which compounds are more likely to interact with P-gp. We have tested the ability of this method to differentiate between binders and nonbinders of P-gp by using consistently measured in vitro experimental data. We also implemented a blind test on a series of peptidic cysteine protease inhibitors with encouraging outcome. Overall, our results suggest that this method provides a qualitative, quick, and inexpensive way of evaluating potential drug efflux problem at the early stages of drug development.
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Affiliation(s)
- Elena Dolghih
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, California, USA.
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Patel JP, Brocks DR. The effect of oral lipids and circulating lipoproteins on the metabolism of drugs. Expert Opin Drug Metab Toxicol 2009; 5:1385-98. [DOI: 10.1517/17425250903176439] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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18
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Belli S, Elsener PM, Wunderli-Allenspach H, Krämer SD. Cholesterol-mediated activation of P-glycoprotein: distinct effects on basal and drug-induced ATPase activities. J Pharm Sci 2009; 98:1905-18. [PMID: 18937360 DOI: 10.1002/jps.21558] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Cholesterol promotes basal and verapamil-induced ATPase activity of P-glycoprotein (P-gp). We investigated whether these effects are related to each other and to the impact of the sterol on bilayer fluidity and verapamil membrane affinity. P-gp was reconstituted in egg-phosphatidylcholine (PhC) liposomes with or without cholesterol, 1,2-dipalmitoyl-phosphatidylcholine (DPPC), alpha-tocopherol (alpha-Toc) or 2,2,5,7,8-pentamethyl-6-chromanol (PMC). Basal and verapamil-induced ATPase activities were studied with an enzymatic assay. Membrane fluidity was characterized with diphenyl-hexatriene anisotropy measurements and membrane affinity by equilibrium dialysis. DPPC (70% mol/mol) decreased the fluidity of PhC bilayers to the same level as 20% cholesterol. PMC (20%) and alpha-Toc (20%) decreased the fluidity to lesser extents. alpha-Toc and PMC, but not DPPC increased the verapamil membrane affinity. While 20% cholesterol strikingly enhanced the basal ATPase activity, none of the other constituents had a similar effect. In contrast, verapamil stimulation of P-gp ATPase activity was not only enabled by cholesterol but also by alpha-Toc and DPPC. PMC had no effect. In conclusion, cholesterol exerts distinct effects on basal and verapamil-induced ATPase activity. The influence on basal ATPase activity is sterol-specific while its effect on verapamil-induced ATPase activity is unspecific and not related to its influence on membrane fluidity and on verapamil membrane affinity.
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Affiliation(s)
- Sara Belli
- Department of Chemistry and Applied Biosciences, Institute of Pharmaceutical Sciences, ETH Zürich, Wolfgang-Pauli-Strasse 10, CH-8093 Zürich, Switzerland
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19
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The relationships of ABCB1 3435C>T and CYP2B6 516G>T with high-density lipoprotein cholesterol in HIV-infected patients receiving Efavirenz. Clin Pharmacol Ther 2009; 86:204-11. [PMID: 19474786 DOI: 10.1038/clpt.2009.78] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Non-nucleoside reverse transcriptase inhibitors (NNRTIs) are associated with a favorable increase in high-density lipoprotein cholesterol (HDL-c) level. Isolated studies have found a direct correlation between efavirenz (EFV) exposure and HDL-c level changes. Here we explore the impact that drug disposition variants associated with EFV exposure have on changes in HDL-c level. Seventy-six patients on first-line EFV-based regimens were genotyped for CYP2B6 516G>T and ABCB1 3435C>T. There was a 37% increase (+0.32 mmol/l, P < 0.001) in mean HDL-c level over 48 weeks, and this was univariately associated with gender (male +0.26 mmol/l, female +0.55 mmol/l; P = 0.03), ABCB1 3435C>T (CC +0.26 mmol/l, CT +0.16 mmol/l, TT +0.54 mmol/l; P(ANOVA) = 0.003) and CYP2B6 516 G>T (GG +0.27 mmol/l, GT +0.29 mmol/l, TT +0.72 mmol/l; P(ANOVA) = 0.08). There was a significant association between the cumulative number of predictive genotypes (CYP2B6 516TT or ABCB1 3435TT) and mean HDL-c level change: (group 0 +0.20 mmol/l, group 1 +0.47 mmol/l, group 2 +1.00 mmol/l; P(ANOVA) < 0.0001). These findings need to be validated in independent cohorts.
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Transport of lipids by ABC proteins: interactions and implications for cellular toxicity, viability and function. Chem Biol Interact 2009; 180:327-39. [PMID: 19426719 DOI: 10.1016/j.cbi.2009.04.012] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2008] [Revised: 04/15/2009] [Accepted: 04/24/2009] [Indexed: 12/16/2022]
Abstract
Members of the ATP-binding cassette (ABC) family of membrane-bound transporters are involved in multiple aspects of transport and redistribution of various lipids and their conjugates. Most ABC transporters localize to the plasma membrane; some are associated with liquid-ordered cholesterol-/sphingolipid-rich microdomains, and to a lesser extent the membranes of the Golgi and endoplasmic reticulum. Hence, ABC transporters are well placed to regulate plasma membrane lipid composition and the efflux and redistribution of structural phospholipids and sphingolipids during periods of cellular stress and recovery. ABC transporters can also modulate cellular sensitivity to extrinsic pro-apoptotic signals through regulation of sphingomyelin-ceramide biosynthesis and metabolism. The functionality of ABC transporters is, in turn, modulated by the lipid content of the microdomains in which they reside. Cholesterol, a major membrane microdomain component, is not only a substrate of several ABC transporters, but also regulates ABC activity through its effects on microdomain structure. Several important bioactive lipid mediators and toxic lipid metabolites are also effluxed by ABC transporters. In this review, the complex interactions between ABC transporters and their lipid/sterol substrates will be discussed and analyzed in the context of their relevance to cellular function, toxicity and apoptosis.
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Eckford PDW, Sharom FJ. Interaction of the P-glycoprotein multidrug efflux pump with cholesterol: effects on ATPase activity, drug binding and transport. Biochemistry 2009; 47:13686-98. [PMID: 19049391 DOI: 10.1021/bi801409r] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Resistance to a broad spectrum of structurally diverse chemotherapeutic drugs (multidrug resistance; MDR) is a major impediment to the treatment of cancer. One cause of MDR is the expression at the tumor cell surface of P-glycoprotein (Pgp), which functions as an ATP-powered multidrug efflux pump. Since Pgp interacts with its substrates after they partition into the lipid bilayer, changes in membrane physicochemical properties may have substantial effects on its functional activity. Various interactions between cholesterol and Pgp have been suggested, including a role for the protein in transbilayer movement of cholesterol. We have characterized several aspects of Pgp-cholesterol interactions, and found that some of the previously reported effects of cholesterol result from inhibition of Pgp ATPase activity by the cholesterol-extracting reagent, methyl-beta-cyclodextrin. The presence of cholesterol in the bilayer modulated the basal and drug-stimulated ATPase activity of reconstituted Pgp in a modest fashion. Both the ability of drugs to bind to the protein and the drug transport and phospholipid flippase functions of Pgp were also affected by cholesterol. The effects of cholesterol on drug binding affinity were unrelated to the size of the compound. Increasing cholesterol content greatly altered the partitioning of hydrophobic drug substrates into the membrane, which may account for some of the observed effects of cholesterol on Pgp-mediated drug transport. Pgp does not appear to mediate the flip-flop of a fluorescent cholesterol analogue across the bilayer. Cholesterol likely modulates Pgp function via effects on drug-membrane partitioning and changes in the local lipid environment of the protein.
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Affiliation(s)
- Paul D W Eckford
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada N1G 2W1
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Calpe-Berdiel L, Escolà-Gil JC, Blanco-Vaca F. New insights into the molecular actions of plant sterols and stanols in cholesterol metabolism. Atherosclerosis 2008; 203:18-31. [PMID: 18692849 DOI: 10.1016/j.atherosclerosis.2008.06.026] [Citation(s) in RCA: 175] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2008] [Revised: 05/15/2008] [Accepted: 06/18/2008] [Indexed: 12/25/2022]
Abstract
Plant sterols and stanols (phytosterols/phytostanols) are known to reduce serum low-density lipoprotein (LDL)-cholesterol level, and food products containing these plant compounds are widely used as a therapeutic dietary option to reduce plasma cholesterol and atherosclerotic risk. The cholesterol-lowering action of phytosterols/phytostanols is thought to occur, at least in part, through competition with dietary and biliary cholesterol for intestinal absorption in mixed micelles. However, recent evidence suggests that phytosterols/phytostanols may regulate proteins implicated in cholesterol metabolism both in enterocytes and hepatocytes. Important advances in the understanding of intestinal sterol absorption have provided potential molecular targets of phytosterols. An increased activity of ATP-binding cassette transporter A1 (ABCA1) and ABCG5/G8 heterodimer has been proposed as a mechanism underlying the hypocholesterolaemic effect of phytosterols. Conclusive studies using ABCA1 and ABCG5/G8-deficient mice have demonstrated that the phytosterol-mediated inhibition of intestinal cholesterol absorption is independent of these ATP-binding cassette (ABC) transporters. Other reports have proposed a phytosterol/phytostanol action on cholesterol esterification and lipoprotein assembly, cholesterol synthesis and apolipoprotein (apo) B100-containing lipoprotein removal. The accumulation of phytosterols in ABCG5/G8-deficient mice, which develop features of human sitosterolaemia, disrupts cholesterol homeostasis by affecting sterol regulatory element-binding protein (SREBP)-2 processing and liver X receptor (LXR) regulatory pathways. This article reviews the progress to date in studying these effects of phytosterols/phytostanols and the molecular mechanisms involved.
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Affiliation(s)
- Laura Calpe-Berdiel
- Servei de Bioquímica, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain
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Ito K. ABCC2/Abcc2 Transport Property in Different Species and its Modulation by Heterogeneous Factors. Drug Metab Pharmacokinet 2008; 23:394-405. [DOI: 10.2133/dmpk.23.394] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Orlowski S, Coméra C, Tercé F, Collet X. Lipid rafts: dream or reality for cholesterol transporters? EUROPEAN BIOPHYSICS JOURNAL: EBJ 2007; 36:869-85. [PMID: 17576551 DOI: 10.1007/s00249-007-0193-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2007] [Revised: 05/11/2007] [Accepted: 05/15/2007] [Indexed: 01/12/2023]
Abstract
As a key constituent of the cell membranes, cholesterol is an endogenous component of mammalian cells of primary importance, and is thus subjected to highly regulated homeostasis at the cellular level as well as at the level of the whole body. This regulation requires adapted mechanisms favoring the handling of cholesterol in aqueous compartments, as well as its transfer into or out of membranes, involving membrane proteins. A membrane exhibits functional properties largely depending on its lipid composition and on its structural organization, which very often involves cholesterol-rich microdomains. Then there is the appealing possibility that cholesterol may regulate its own transmembrane transport at a purely functional level, independently of any transcriptional regulation based on cholesterol-sensitive nuclear factors controling the expression level of lipid transport proteins. Indeed, the main cholesterol "transporters" presently believed to mediate for instance the intestinal absorption of cholesterol, that are SR-BI, NPC1L1, ABCA1, ABCG1, ABCG5/G8 and even P-glycoprotein, all present privileged functional relationships with membrane cholesterol-containing microdomains. In particular, they all more or less clearly induce membrane disorganization, supposed to facilitate cholesterol exchanges with the close aqueous medium. The actual lipid substrates handled by these transporters are not yet unambiguously determined, but they likely concern the components of membrane microdomains. Conversely, raft alterations may provide specific modulations of the transporter activities, as well as they can induce indirect effects via local perturbations of the membrane. Finally, these cholesterol transporters undergo regulated intracellular trafficking, with presumably some relationships to rafts which remain to be clarified.
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Affiliation(s)
- Stéphane Orlowski
- SB2SM/IBTS and URA 2096 CNRS, CEA, Centre de Saclay, 91191, Gif-sur-Yvette cedex, France.
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Levy E, Spahis S, Sinnett D, Peretti N, Maupas-Schwalm F, Delvin E, Lambert M, Lavoie MA. Intestinal cholesterol transport proteins: an update and beyond. Curr Opin Lipidol 2007; 18:310-8. [PMID: 17495606 DOI: 10.1097/mol.0b013e32813fa2e2] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE OF REVIEW Various studies have delineated the causal role of dietary cholesterol in atherogenesis. Strategies have thus been developed to minimize cholesterol absorption, and cholesterol transport proteins found at the apical membrane of enterocytes have been extensively investigated. This review focuses on recent progress related to various brush-border proteins that are potentially involved in alimentary cholesterol transport. RECENT FINDINGS Molecular mechanisms responsible for dietary cholesterol and plant sterol uptake have not been completely defined. Growing evidence, however, supports the concept that several proteins are involved in mediating intestinal cholesterol transport, including SR-BI, NPC1L1, CD36, aminopeptidase N, P-glycoprotein, and the caveolin-1/annexin-2 heterocomplex. Other ABC family members (ABCA1 and ABCG5/ABCG8) act as efflux pumps favoring cholesterol export out of absorptive cells into the lumen or basolateral compartment. Several of these cholesterol carriers influence intracellular cholesterol homeostasis and are controlled by transcription factors, including RXR, LXR, SREBP-2 and PPARalpha. The lack of responsiveness of NPC1L1-deficient mice to ezetimibe suggests that NPC1L1 is likely to be the principal target of this cholesterol-lowering drug. SUMMARY The understanding of the role, genetic regulation and coordinated function of proteins mediating intestinal cholesterol transport may lead to novel ways of treating cardiovascular disease.
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Affiliation(s)
- Emile Levy
- Research Centre, CHU-Sainte-Justine, Québec, Canada.
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Bucher K, Belli S, Wunderli-Allenspach H, Krämer SD. P-glycoprotein in proteoliposomes with low residual detergent: the effects of cholesterol. Pharm Res 2007; 24:1993-2004. [PMID: 17497080 DOI: 10.1007/s11095-007-9326-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2007] [Accepted: 04/25/2007] [Indexed: 11/29/2022]
Abstract
PURPOSE There is evidence that cholesterol affects the ATPase and transport functions of P-glycoprotein (P-gp). To study the influence of cholesterol on P-gp in a well defined lipid environment, we reconstituted P-gp in egg phosphatidylcholine (PhC) and PhC/cholesterol proteoliposomes with negligible residual amounts of detergents. MATERIALS AND METHODS P-gp proteoliposomes were prepared by continuous dialysis from micelles consisting of P-gp, lipids, sodium dodecyl sulfate and cholate. Basal and modulator-induced ATPase activities were studied in an established enzyme assay. Modulator affinities to P-gp and to the lipid bilayers were determined by equilibrium dialysis. RESULTS In the absence of cholesterol the basal ATPase activity was six fold lower than in the presence of 20 or 40% cholesterol, and no P-gp binding and ATPase induction was detected for the tested modulators verapamil and progesterone. In proteoliposomes containing 20 and 40% cholesterol, respectively, the modulators showed significant P-gp binding and ATPase activation. The concentration of the modulators for half maximal activation of the ATPase was higher with 40% than with 20% cholesterol. CONCLUSIONS Cholesterol influences P-gp in three ways: (a) it enhances its basal ATPase activity, (b) it renders P-gp sensitive towards the modulators verapamil and progesterone and (c) it affects the modulator concentration at half maximal ATPase activation.
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Affiliation(s)
- Karsten Bucher
- Department of Chemistry and Applied Biosciences, Institute of Pharmaceutical Sciences, ETH Zurich, Wolfgang-Pauli-Strasse 10, 8093, Zurich, Switzerland
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Sharom FJ. Shedding light on drug transport: structure and function of the P-glycoprotein multidrug transporter (ABCB1). Biochem Cell Biol 2007; 84:979-92. [PMID: 17215884 DOI: 10.1139/o06-199] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
P-glycoprotein (Pgp; ABCB1), a member of the ATP-binding cassette (ABC) superfamily, exports structurally diverse hydrophobic compounds from the cell, driven by ATP hydrolysis. Pgp expression has been linked to the efflux of chemotherapeutic drugs in human cancers, leading to multidrug resistance (MDR). The protein also plays an important physiological role in limiting drug uptake in the gut and entry into the brain. Substrates partition into the lipid bilayer before interacting with Pgp, which has been proposed to function as a hydrophobic vacuum cleaner. Low- and medium-resolution structural models of Pgp suggest that the 2 nucleotide-binding domains are closely associated to form a nucleotide sandwich dimer. Pgp is an outwardly directed flippase for fluorescent phospholipid and glycosphingolipid derivatives, which suggests that it may also translocate drug molecules from the inner to the outer membrane leaflet. The ATPase catalytic cycle of the protein is thought to proceed via an alternating site mechanism, although the details are not understood. The lipid bilayer plays an important role in Pgp function, and may regulate both the binding and transport of drugs. This review focuses on the structure and function of Pgp, and highlights the importance of fluorescence spectroscopic techniques in exploring the molecular details of this enigmatic transporter.
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MESH Headings
- ATP Binding Cassette Transporter, Subfamily B
- ATP Binding Cassette Transporter, Subfamily B, Member 1/chemistry
- ATP Binding Cassette Transporter, Subfamily B, Member 1/genetics
- ATP Binding Cassette Transporter, Subfamily B, Member 1/metabolism
- ATP Binding Cassette Transporter, Subfamily B, Member 1/physiology
- ATP-Binding Cassette Transporters/metabolism
- Adenosine Triphosphate/metabolism
- Animals
- Awards and Prizes
- Biological Transport/drug effects
- Drug Resistance, Multiple
- Humans
- Models, Biological
- Models, Molecular
- Organic Anion Transporters/metabolism
- Spectrometry, Fluorescence
- Structure-Activity Relationship
- Substrate Specificity
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Affiliation(s)
- Frances J Sharom
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON N1G 2W1, Canada.
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Pál A, Méhn D, Molnár E, Gedey S, Mészáros P, Nagy T, Glavinas H, Janáky T, von Richter O, Báthori G, Szente L, Krajcsi P. Cholesterol potentiates ABCG2 activity in a heterologous expression system: improved in vitro model to study function of human ABCG2. J Pharmacol Exp Ther 2007; 321:1085-94. [PMID: 17347325 DOI: 10.1124/jpet.106.119289] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
ABCG2, a transporter of the ATP-binding cassette family, is known to play a prominent role in the absorption, distribution, metabolism, and excretion of xenobiotics. Drug-transporter interactions are commonly screened by high-throughput systems using transfected insect and/or human cell lines. The determination of ABCG2-ATPase activity is one method to identify ABCG2 substrate and inhibitors. We demonstrate that the ATPase activities of the human ABCG2 transfected Sf9 cell membranes (MXR-Sf9) and ABCG2-overexpressing human cell membranes (MXR-M) differ. Variation due to disparity in the glycosylation level of the protein had no effect on the transporter. The influence of cholesterol on ABCG2-ATPase activity was investigated because the lipid compositions of insect and human cells are largely different from each other. Differences in cholesterol content, shown by cholesterol loading and depletion experiments, conferred the difference in stimulation of basal ABCG2-ATPase of the two cell membranes. Basal ABCG2-ATPase activity could be stimulated by sulfasalazine, prazosin, and topotecan, known substrates of ABCG2 in cholesterol-loaded MXR-Sf9 and MXR-M cell membranes. In contrast, ABCG2-ATPase could not be stimulated in MXR-Sf9 or in cholesterol-depleted MXR-M membranes. Moreover, cholesterol loading significantly improved the drug transport into inside-out membrane vesicles prepared from MXR-Sf9 cells. MXR-M and cholesterol-loaded MXR-Sf9 cell membranes displayed similar ABCG2-ATPase activity and vesicular transport. Our study indicates an essential role of membrane cholesterol for the function of ABCG2.
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Affiliation(s)
- A Pál
- SOLVO Biotechnology, Central Hungarian Innovations Center, Gyár u. 2., H-2040 Budaörs, Hungary
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Meyer dos Santos S, Meyer Dos Santos S, Weber CC, Franke C, Müller WE, Eckert GP. Cholesterol: Coupling between membrane microenvironment and ABC transporter activity. Biochem Biophys Res Commun 2007; 354:216-21. [PMID: 17223079 DOI: 10.1016/j.bbrc.2006.12.202] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2006] [Accepted: 12/23/2006] [Indexed: 01/16/2023]
Abstract
Lipid composition of biological membranes is closely related to the function of the ATP-binding cassette (ABC) transporter P-Glycoprotein (Pgp). Herein, we studied how membrane physico-chemical properties affect Pgp-activity. We effectively modulated the cellular cholesterol content using methyl-beta-cyclodextrin (MbetaCD) and MbetaCD-cholesterol-inclusion complex. Pgp was not liberated from the plasma membrane during cholesterol modulation and functional inhibition of Pgp was related to varying cholesterol levels in the plasma membrane. Our data indicate that membrane fluidity does not solely account for cholesterol dependent modifications of Pgp-activity. Therefore, we isolated lipid rafts and examined distinct membrane microdomains. Both depletion and cholesterol enrichment induces a disassembly of lipid rafts. In cholesterol-depleted cell membranes a shift in the Pgp localisation to detergent soluble fractions was observed. Enrichment of membrane cholesterol changed lipid raft distribution but not the localisation of Pgp. From our data we conclude that Pgp-transport capacity depends on accurate lipid raft properties.
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Affiliation(s)
- Sascha Meyer dos Santos
- Department of Pharmacology, ZAFES, Biocenter Niederursel, N260, Max-von-Laue Str. 9, University of Frankfurt, Germany
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Leon C, Sachs-Barrable K, Wasan KM. Does p-glycoprotein play a role in gastrointestinal absorption and cellular transport of dietary cholesterol? Drug Dev Ind Pharm 2006; 32:779-82. [PMID: 16885132 DOI: 10.1080/03639040600559073] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
This commentary discusses the potential role of p-glycoprotein (Pgp) on the gastrointestinal absorption and cellular transport of dietary cholesterol. This is currently a controversial issue due to the conflicting evidence about the role of this ABC transporter in cholesterol transport. During the preparation of this commentary, several key publications on this topic arguing for and against this mechanism have been published. If true, this mechanism of Pgp could represent a novel role for Pgp and provide a potentially new molecular target for drug design and development.
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Affiliation(s)
- C Leon
- Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, B.C., Canada
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Tubic M, Wagner D, Spahn-Langguth H, Weiler C, Wanitschke R, Böcher WO, Langguth P. Effects of controlled-release on the pharmacokinetics and absorption characteristics of a compound undergoing intestinal efflux in humans. Eur J Pharm Sci 2006; 29:231-9. [PMID: 16713700 DOI: 10.1016/j.ejps.2006.04.005] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2006] [Accepted: 04/02/2006] [Indexed: 01/24/2023]
Abstract
OBJECTIVE The number of active pharmaceutical ingredients (API) undergoing inhibitable and saturable intestinal efflux is considerable. As a consequence, absorption and bioavailability may depend on the intestinal concentration profile of the drug and may vary as a function of dose and release rate of the drug from the dosage form. The impact of controlled versus immediate-release on the absorption of P-glycoprotein substrates is currently unknown. Thus, the main focus of the present study was a comparison of the pharmacokinetics of the P-gp model substrate talinolol following administration of immediate-release (IR) and controlled-release (CR) tablets to healthy human volunteers with a particular focus on the absorption characteristics of the active pharmaceutical ingredients. METHODS Talinolol immediate-release (Cordanum), 100mg), one controlled-release (100mg) and two controlled-release tablets (200mg) were administered as single doses to fasting healthy volunteers in a crossover design with a 1 week washout period between treatments. Sufficient blood and urine samples were drawn and analysed using a specific HPLC method with UV detection to describe the resulting plasma and urinary excretion versus time profiles. RESULTS The bioavailability of talinolol in term of AUC(0-->infinity) for IR talinolol was approximately twice as high as compared to the administration of the same dose in a controlled-release dosage form. After administration of talinolol IR tablets, the drug was rapidly absorbed and reached maximum concentrations C(max) of 204.5 ng/ml+/-121.8 (means+/-S.D.) 2h after dosing. The terminal half-life of the drug averaged 19.8h following IR administration in comparison to 32 h under CR dosing conditions. Following administration of the IR dosage form, significant secondary peaks were observed in one healthy subject. Secondary peaks were not clearly apparent in the CR plasma profiles. CONCLUSION The present study demonstrates a considerable loss of bioavailability of drugs that are substrates of intestinal secretory transporters upon their administration in controlled-release dosage forms.
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Affiliation(s)
- Marija Tubic
- Biopharmacy und Pharmaceutical Technology, Institute for Pharmacy, Johannes Gutenberg-University, Staudinger Weg 5, 55099 Mainz, Germany
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Radeva G, Perabo J, Sharom FJ. P-Glycoprotein is localized in intermediate-density membrane microdomains distinct from classical lipid rafts and caveolar domains. FEBS J 2005; 272:4924-37. [PMID: 16176266 DOI: 10.1111/j.1742-4658.2005.04905.x] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
P-glycoprotein (Pgp), a member of the ATP-binding cassette (ABC) superfamily responsible for the ATP-driven extrusion of diverse hydrophobic molecules from cells, is a cause of multidrug resistance in human tumours. Pgp can also operate as a phospholipid and glycosphingolipid flippase, and has been functionally linked to cholesterol, suggesting that it might be associated with sphingolipid-cholesterol microdomains in cell membranes. We have used nonionic detergent extraction and density gradient centrifugation of extracts from the multidrug-resistant Chinese hamster ovary cell line, CH(R)B30, to address this question. Our data indicate that Pgp is localized in intermediate-density membrane microdomains different from classical lipid rafts enriched in Src-family kinases. We demonstrate that Brij-96 can selectively isolate the Pgp domains, separating them from the caveolar and classical lipid rafts. Pgp was found entirely in the Brij-96-insoluble domains, and only partially in the Triton X-100-insoluble membrane microdomains. We studied the sensitivity of these domains to cholesterol removal, as well as their relationship to GM(1) ganglioside- and caveolin-1-enriched caveolar domains. We found that the buoyant density of the Brij-96-based Pgp-containing microdomains was sensitive to cholesterol removal by methyl-beta-cyclodextrin. The Brij-96 domains retained their structural integrity after cholesterol depletion while, in contrast, the Triton X-100-based caveolin-1/GM(1) microdomains did not. Using confocal fluorescence microscopy, we determined that caveolin-1 and GM(1) colocalized, while Pgp and caveolin-1, or Pgp and GM(1), did not. Our results suggest that Pgp does not interact directly with caveolin-1, and is localized in intermediate-density domains, distinct from classical lipid rafts and caveolae, which can be isolated using Brij-96.
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Affiliation(s)
- Galina Radeva
- Department of Molecular and Cellular Biology, University of Guelph, Ontario, Canada
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Pohl A, Devaux PF, Herrmann A. Function of prokaryotic and eukaryotic ABC proteins in lipid transport. Biochim Biophys Acta Mol Cell Biol Lipids 2004; 1733:29-52. [PMID: 15749056 DOI: 10.1016/j.bbalip.2004.12.007] [Citation(s) in RCA: 116] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2004] [Revised: 11/08/2004] [Accepted: 12/16/2004] [Indexed: 12/23/2022]
Abstract
ATP binding cassette (ABC) proteins of both eukaryotic and prokaryotic origins are implicated in the transport of lipids. In humans, members of the ABC protein families A, B, C, D and G are mutated in a number of lipid transport and metabolism disorders, such as Tangier disease, Stargardt syndrome, progressive familial intrahepatic cholestasis, pseudoxanthoma elasticum, adrenoleukodystrophy or sitosterolemia. Studies employing transfection, overexpression, reconstitution, deletion and inhibition indicate the transbilayer transport of endogenous lipids and their analogs by some of these proteins, modulating lipid transbilayer asymmetry. Other proteins appear to be involved in the exposure of specific lipids on the exoplasmic leaflet, allowing their uptake by acceptors and further transport to specific sites. Additionally, lipid transport by ABC proteins is currently being studied in non-human eukaryotes, e.g. in sea urchin, trypanosomatides, arabidopsis and yeast, as well as in prokaryotes such as Escherichia coli and Lactococcus lactis. Here, we review current information about the (putative) role of both pro- and eukaryotic ABC proteins in the various phenomena associated with lipid transport. Besides providing a better understanding of phenomena like lipid metabolism, circulation, multidrug resistance, hormonal processes, fertilization, vision and signalling, studies on pro- and eukaryotic ABC proteins might eventually enable us to put a name on some of the proteins mediating transbilayer lipid transport in various membranes of cells and organelles. It must be emphasized, however, that there are still many uncertainties concerning the functions and mechanisms of ABC proteins interacting with lipids. In particular, further purification and reconstitution experiments with an unambiguous role of ATP hydrolysis are needed to demonstrate a clear involvement of ABC proteins in lipid transbilayer asymmetry.
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Affiliation(s)
- Antje Pohl
- Humboldt-University Berlin, Institute of Biology, Invalidenstr. 42, D-10115 Berlin, Germany.
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de Boer AG, van der Sandt ICJ, Gaillard PJ. The role of drug transporters at the blood-brain barrier. Annu Rev Pharmacol Toxicol 2003; 43:629-56. [PMID: 12415123 DOI: 10.1146/annurev.pharmtox.43.100901.140204] [Citation(s) in RCA: 140] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The blood-brain barrier (BBB) is a dynamic interface between the blood and the brain. It eliminates (toxic) substances from the endothelial compartment and supplies the brain with nutrients and other (endogenous) compounds. It can be considered as an organ protecting the brain and regulating its homeostasis. Until now, many transport systems have been discovered that play an important role in maintaining BBB integrity and brain homeostasis. In this review, we focus on the role of carrier- and receptor-mediated transport systems (CMT, RMT) at the BBB. These include CMT systems, such as P-glycoprotein, multidrug-resistance proteins 1-7, nucleoside transporters, organic anion transporters, and large amino-acid transporters; RMT systems, such as the transferrin-1 and -2 receptors; and the scavenger receptors SB-AI and SB-BI.
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Affiliation(s)
- A G de Boer
- Blood-Brain Barrier Research Group, Division of Pharmacology, Leiden/Amsterdam Center for Drug Research, University of Leiden, The Netherlands.
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Ferreira-Pereira A, Marco S, Decottignies A, Nader J, Goffeau A, Rigaud JL. Three-dimensional reconstruction of the Saccharomyces cerevisiae multidrug resistance protein Pdr5p. J Biol Chem 2003; 278:11995-9. [PMID: 12551908 DOI: 10.1074/jbc.m212198200] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Pdr5p, the major multidrug exporter in Saccharomyces cerevisiae, is a member of the ATP-binding cassette (ABC) superfamily. Pdr5p shares similar mechanisms of substrate recognition and transport with the human MDR1-Pgp, despite an inverted topology of transmembrane and ATP-binding domains. The hexahistidine-tagged Pdr5p multidrug transporter was highly overexpressed in yeast strains where other ABC genes have been deleted. After solubilization and purification, the 160-kDa recombinant Pdr5p has been reconstituted into a lipid bilayer. Controlled detergent removal from Pdr5p-lipid-detergent micelles allowed the production of peculiar square-shaped particles coexisting with liposomes and proteoliposomes. These particles having 11 nm in side were well suited for single particle analysis by electron microscopy. From such analysis, a computed volume has been determined at 25-A resolution, giving insight into the structural organization of Pdr5p. Comparison with the reported structures of different bacterial ABC transporters was consistent with a dimeric organization of Pdr5p in the square particles. Each monomer was composed of three subregions corresponding to a membrane region of about 50 A in height that joins two well separated protruding stalks of about 40 A in height, ending each one with a cytoplasmic nucleotide-binding domain (NBD) lobe of about 50-60 A in diameter. The three-dimensional reconstruction of Pdr5p revealed a close arrangement and a structural asymmetric organization of the two NBDs that appeared oriented perpendicularly within a monomer. The existence of different angular positions of the NBDs, with respect to the stalks, suggest rotational movements during the catalytic cycle.
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Affiliation(s)
- Antonio Ferreira-Pereira
- Departamento de Analises Clinicas e Toxicologicas, Faculdade de Farmacia, Universidade Federal do Rio de Janeiro, CEP 21949-900, Rio de Janeiro, Brazil
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Albrecht C, Elliott JI, Sardini A, Litman T, Stieger B, Meier PJ, Higgins CF. Functional analysis of candidate ABC transporter proteins for sitosterol transport. BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1567:133-42. [PMID: 12488046 DOI: 10.1016/s0005-2736(02)00608-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Two ATP-binding cassette (ABC) proteins, ABCG5 and ABCG8, have recently been associated with the accumulation of dietary cholesterol in the sterol storage disease sitosterolemia. These two 'half-transporters' are assumed to dimerize to form the complete sitosterol transporter which reduces the absorption of sitosterol and related molecules in the intestine by pumping them back into the lumen. Although mutations altering ABCG5 and ABCG8 are found in affected patients, no functional demonstration of sitosterol transport has been achieved. In this study, we investigated whether other ABC transporters implicated in lipid movement and expressed in tissues with a role in sterol synthesis and absorption, might also be involved in sitosterol transport. Transport by the multidrug resistance P-glycoprotein (P-gp; Abcb1), the multidrug resistance-associated protein (Mrp1; Abcc1), the breast cancer resistance protein (Bcrp; Abcg2) and the bile salt export pump (Bsep; Abcb11) was assessed using several assays. Unexpectedly, none of the candidate proteins mediated significant sitosterol transport. This has implications for the pathology of sitosterolemia. In addition, the data suggest that otherwise broad-specific ABC transporters have acquired specificity to exclude sitosterol and related sterols like cholesterol presumably because the abundance of cholesterol in the membrane would interfere with their action; in consequence, specific transporters have evolved to handle these sterols.
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Affiliation(s)
- C Albrecht
- MRC Clinical Sciences Centre, Faculty of Medicine, Imperial College, Hammersmith Hospital Campus, Du Cane Rd., London W12 ONN, UK.
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Abstract
The ATP-binding cassette (ABC) transporters are a family of large proteins in membranes and are able to transport a variety of compounds through membranes against steep concentration gradients at the cost of ATP hydrolysis. The available outline of the human genome contains 48 ABC genes; 16 of these have a known function and 14 are associated with a defined human disease. Major physiological functions of ABC transporters include the transport of lipids, bile salts, toxic compounds, and peptides for antigen presentation or other purposes. We review the functions of mammalian ABC transporters, emphasizing biochemical mechanisms and genetic defects. Our overview illustrates the importance of ABC transporters in human physiology, toxicology, pharmacology, and disease. We focus on three topics: (a) ABC transporters transporting drugs (xenotoxins) and drug conjugates. (b) Mammalian secretory epithelia using ABC transporters to excrete a large number of substances, sometimes against a steep concentration gradient. Several inborn errors in liver metabolism are due to mutations in one of the genes for these pumps; these are discussed. (c) A rapidly increasing number of ABC transporters are found to play a role in lipid transport. Defects in each of these transporters are involved in human inborn or acquired diseases.
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Affiliation(s)
- P Borst
- Division of Molecular Biology, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX, Amsterdam, The Netherlands.
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Tatidis L, Masquelier M, Vitols S. Elevated uptake of low density lipoprotein by drug resistant human leukemic cell lines. Biochem Pharmacol 2002; 63:2169-80. [PMID: 12110376 DOI: 10.1016/s0006-2952(02)01018-3] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Overexpression of a 170kD membrane glycoprotein, P-glycoprotein (Pgp), which acts as an energy dependent efflux pump for cytotoxic drugs is believed to be one of the factors that is responsible for clinical drug resistance. Recent studies suggest that Pgp is also responsible for the intracellular transport of cholesterol from the plasma membrane to the endoplasmic reticulum. Leukemic cells from patients with acute myelogenous leukemia have an elevated uptake of low density lipoprotein (LDL) when compared with white blood cells from healthy individuals. Since elevated LDL receptor expression and multidrug resistance are both common events in leukemic cells, we investigated LDL receptor expression in sensitive and drug resistant human leukemic cell lines. We found a 2- to 10-fold higher uptake of LDL in five out of five drug resistant K562 cell lines. All three drug resistant HL60 cell lines studied also had higher uptake than the parental cells. The LDL receptor expression in vincristine resistant Pgp positive K562 cells was less sensitive to downregulation by sterols than in parental cells. There was no selective effect of the Pgp inhibitor PSC-833 or other Pgp modulators on LDL receptor activity in Pgp positive cells. Since also resistant Pgp, multidrug resistance protein 1, and breast cancer resistance protein negative cells exhibited an elevated LDL receptor activity, we conclude that overexpression of these proteins is not the mechanism behind the elevated LDL uptake in the drug resistant leukemic cell lines. The findings are of interest for the concept of using lipoproteins as carriers of cytotoxic drugs in cancer treatment.
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Affiliation(s)
- Loukas Tatidis
- Division of Clinical Pharmacology, Department of Medicine, Karolinska Institute & Hospital, Stockholm, Sweden.
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Demeule M, Régina A, Jodoin J, Laplante A, Dagenais C, Berthelet F, Moghrabi A, Béliveau R. Drug transport to the brain: key roles for the efflux pump P-glycoprotein in the blood-brain barrier. Vascul Pharmacol 2002; 38:339-48. [PMID: 12529928 DOI: 10.1016/s1537-1891(02)00201-x] [Citation(s) in RCA: 141] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
1. The blood-brain barrier (BBB) contributes to brain homeostastis and fulfills a protective function by controlling the access of solutes and toxic substances to the central nervous system (CNS). The efflux transporter P-glycoprotein (P-gp) is a key element of the molecular machinery that confers special permeability properties to the BBB. 2. P-gp, which was initially recognized for its ability to expel anticancer drugs from multidrug-resistant cancer cells, is strongly expressed in brain capillaries. Its expression in the BBB limits the accumulation of many hydrophobic molecules and potentially toxic substances in the brain. 3. The purpose of this review is to summarize the current state of knowledge about the expression of P-gp, its cellular localization as well as its possible functions in the BBB.
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Affiliation(s)
- Michel Demeule
- Laboratoire de Médecine Moléculaire, Hôpital Sainte-Justine-Université du Québec à Montréal, C.P. 8888, Succursale Centre-ville, Montréal, Quebec, Canada H3C 3P8
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Teodori E, Dei S, Scapecchi S, Gualtieri F. The medicinal chemistry of multidrug resistance (MDR) reversing drugs. FARMACO (SOCIETA CHIMICA ITALIANA : 1989) 2002; 57:385-415. [PMID: 12058813 DOI: 10.1016/s0014-827x(02)01229-6] [Citation(s) in RCA: 131] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Multidrug resistance (MDR) is a kind of resistance of cancer cells to multiple classes of chemotherapic drugs that can be structurally and mechanistically unrelated. Classical MDR regards altered membrane transport that results in lower cell concentrations of cytotoxic drug and is related to the over expression of a variety of proteins that act as ATP-dependent extrusion pumps. P-glycoprotein (Pgp) and multidrug resistance protein (MRP1) are the most important and widely studied members of the family that belongs to the ABC superfamily of transporters. It is apparent that, besides their role in cancer cell resistance, these proteins have multiple physiological functions as well, since they are expressed also in many important non-tumoural tissues and are largely present in prokaryotic organisms. A number of drugs have been identified which are able to reverse the effects of Pgp, MRPI and sister proteins, on multidrug resistance. The first MDR modulators discovered and studied in clinical trials were endowed with definite pharmacological actions so that the doses required to overcome MDR were associated with unacceptably high side effects. As a consequence, much attention has been focused on developing more potent and selective modulators with proper potency, selectivity and pharmacokinetics that can be used at lower doses. Several novel MDR reversing agents (also known as chemosensitisers) are currently undergoing clinical evaluation for the treatment of resistant tumours. This review is concerned with the medicinal chemistry of MDR reversers, with particular attention to the drugs that are presently in development.
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Affiliation(s)
- E Teodori
- Dipartimento di Scienze Farmaceutiche, Universita' di Firenze, Florence, Italy
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Kohli A, Mukhopadhyay K, Rattan A, Prasad R. In vitro low-level resistance to azoles in Candida albicans is associated with changes in membrane lipid fluidity and asymmetry. Antimicrob Agents Chemother 2002; 46:1046-52. [PMID: 11897588 PMCID: PMC127087 DOI: 10.1128/aac.46.4.1046-1052.2002] [Citation(s) in RCA: 102] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The present study tracks the development of low-level azole resistance in in vitro fluconazole-adapted strains of Candida albicans, which were obtained by serially passaging a fluconazole-susceptible dose-dependent strain, YO1-16 (fluconazole MIC, 16 microg ml(-1)) in increasing concentrations of fluconazole, resulting in strains YO1-32 (fluconazole MIC, 32 microg ml(-1)) and YO1-64 (MIC, 64 microg ml(-1)). We show that acquired resistance to fluconazole in this series of isolates is not a random process but is a gradually evolved complex phenomenon that involves multiple changes, which included the overexpression of ABC transporter genes, e.g., CDR1 and CDR2, and the azole target enzyme, ERG11. The sequential rise in fluconazole MICs in these isolates was also accompanied by cross-resistance to other azoles and terbinafine. Interestingly, fluorescent polarization measurements performed by using the fluorescent probe 1,6-diphenyl-1,3,5-hexatriene revealed that there was a gradual increase in membrane fluidity of adapted strains. The increase in fluidity was reflected by observed change in membrane order, which was considerably decreased (decrease in fluorescence polarization values, P value) in the adapted strain (P value of 0.1 in YO1-64, compared to 0.19 in the YO1-16 strain). The phospholipid composition of the adapted strain was not significantly altered; however, ergosterol content was reduced in YO1-64 from that in the YO1-16 strain. The asymmetrical distribution of phosphatidylethanolamine (PE) between two monolayers of plasma membrane was also changed, with PE becoming more exposed to the outer monolayer in the YO1-64 strain. The results of the present study suggest for the first time that changes in the status of membrane lipid phase and asymmetry could contribute to azole resistance in C. albicans.
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Affiliation(s)
- Avmeet Kohli
- Membrane Biology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
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42
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Chami M, Steinfels E, Orelle C, Jault JM, Di Pietro A, Rigaud JL, Marco S. Three-dimensional structure by cryo-electron microscopy of YvcC, an homodimeric ATP-binding cassette transporter from Bacillus subtilis. J Mol Biol 2002; 315:1075-85. [PMID: 11827477 DOI: 10.1006/jmbi.2001.5309] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
YvcC, a multidrug transporter from Bacillus subtilis, is a member of the ATP-binding cassette superfamily, highly homologous to each half of human multidrug-resistance P-glycoprotein and to several other bacterial half-ABC transporters. Here, the purified recombinant histidine-tagged YvcC has been reconstituted into a lipid bilayer. Controlled and partial detergent removal from YvcC-lipid micelles allowed the production of particularly interesting lipid-detergent-YvcC ring-shaped particles, about 40 nm in diameter, well suited for single particle analysis by cryo-electron microscopy. Furthermore, binding of these histidine-tagged ring-shaped particles to lipid layers functionalized with a Ni(2+)-chelating head group generated a preferential perpendicular orientation, eliminating the missing cone in the final three-dimensional reconstruction. From such analysis, a computed volume has been determined to 2.5 nm resolution giving a detailed insight into the structural organization of this half-ABC transporter within a membrane. The repetitive unit in the ring-shaped particles is consistent with a homodimeric organization of YvcC. Each subunit was composed of three domains: a 5 nm height transmembrane region, a stalk of about 4 nm in height and 2 nm in diameter, and a cytoplasmic lobe of about 5-6 nm in diameter. The latest domain, which fitted with the reported X-ray structure of HisP, was identified as the nucleotide-binding domain (NBD). The 3D reconstruction of the YvcC homodimer well compared with the very recent X-ray crystallographic data on the MsbA homodimer from Escherichia coli, supporting the existence of a central open chamber between the two subunits constituting the homodimer. In addition, the 3D reconstruction of YvcC embedded in a membrane revealed an asymmetric organization of the two NBDs sites within the homodimer, as well as a dimeric interaction between two homodimers.
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Affiliation(s)
- Mohamed Chami
- Institut Curie Section Recherche, UMR-CNRS 168 et LRC-CEA 8, 11 Rue Pierre et Marie Curie, Paris Cedex 05, 75231, France
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Wang EJ, Casciano CN, Clement RP, Johnson WW. Active transport of fluorescent P-glycoprotein substrates: evaluation as markers and interaction with inhibitors. Biochem Biophys Res Commun 2001; 289:580-5. [PMID: 11716514 DOI: 10.1006/bbrc.2001.6000] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
With P-glycoprotein (P-gp) continuing to have prominence among the ABC transporters for its ability to remove various xenobiotics from many cell types, accurate and robust methods for estimating the exposure of drug, carcinogen, toxicant, pesticide, and even some endobiotics to tissues and cells affected by P-gp are valuable. The inhibition of P-gp active transport of molecules, therefore, has often been quantified by concentration dependence of inhibitor effect on fluorescent substrate marker efflux mediated by this enzyme, with much evidence indicating two asymmetric yet interdependent substrate binding sites on P-gp. A uniqueness in the pair of binding sites could result in distinct effects of an inhibitor on the transport of certain substrates, thus leading to differences in fluorescent substrate responsiveness or sensitivity. Seven different fluorescent substrates of P-gp were quantitatively tested for their responsiveness to inhibition by a wide range of P-gp substrates/inhibitors. Interesting differences were observed in the IC(50) values caused by each of the inhibitors employed, in part exemplified by DNR and LDS being generally more sensitive to inhibition effects than any other fluorescent marker. However, no clear trend emerged to designate any fluorochrome marker as the most or least responsive to inhibition. Furthermore, LDS is more sensitive to some P-gp inhibitors than the substrate marker DNR, generally the most responsive. These results support the assertion of two unequal substrate binding sites that are allosterically dependent on each other. Therefore, an inhibitor that favors binding to the site opposite from that favored by a particular marker may have significant transduced effects through the protein between the two binding sites. Nevertheless, although either DNR or LDS is generally the fluorescent substrate most responsive to inhibition, there may be other substrates yet even more sensitive.
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Affiliation(s)
- E J Wang
- Drug Metabolism and Pharmacokinetics, Schering-Plough Research Institute, Lafayette, New Jersey 07848, USA
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Drobnik W, Lindenthal B, Lieser B, Ritter M, Christiansen Weber T, Liebisch G, Giesa U, Igel M, Borsukova H, Büchler C, Fung-Leung WP, Von Bergmann K, Schmitz G. ATP-binding cassette transporter A1 (ABCA1) affects total body sterol metabolism. Gastroenterology 2001; 120:1203-11. [PMID: 11266384 DOI: 10.1053/gast.2001.23250] [Citation(s) in RCA: 104] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
BACKGROUND AND AIMS Members of the family of ABC transporters are involved in different processes of sterol metabolism, and ABCA1 was recently identified as a key regulator of high-density lipoprotein (HDL) metabolism. Our aim was to further analyze the role of ABCA1 in cholesterol metabolism. METHODS ABCA1-deficient mice (ABCA1-/-) and wild-type mice were compared for different aspects of sterol metabolism. Intestinal cholesterol absorption was determined by a dual stable isotope technique, and analysis of fecal, plasma, and tissue sterols was performed by gas chromatography/mass spectrometry. Key regulators of sterol metabolism were investigated by Northern and Western blot analyses or enzyme activity assays. RESULTS ABCA1-disrupted sv129/C57BL/6 hybrid mice showed a significant reduction in intestinal cholesterol absorption. The decrease in cholesterol absorption was followed by an enhanced fecal loss of neutral sterols, whereas fecal bile acid excretion was not affected. Total body cholesterol synthesis was significantly increased, with enhanced 3-hydroxy-3-methyglutaryl-coenzyme A (HMG-CoA) reductase observed in adrenals and spleen. In addition, ABCA1-/- mice showed markedly increased concentrations of cholesterol precursors in the plasma, lung, intestine, and feces. Reduced HMG-CoA reductase messenger RNA and enzyme activity in the liver suggest that enhanced cholesterol synthesis in ABCA1-/- mice occurs in peripheral tissues rather than the liver. CONCLUSIONS The metabolism of cholesterol and cholesterol precursors is markedly affected by a lack of ABCA1 function.
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Affiliation(s)
- W Drobnik
- Institute for Clinical Chemistry and Laboratory Medicine, University of Regensburg, D-93042 Regensburg, Germany
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Abstract
The role of the ATP-binding cassette transporter 1 (ABCA1) in cellular lipid efflux and high density lipoprotein metabolism has been recently documented by mutations in genetic HDL deficiency syndromes such as classical Tangier disease. Analysis of ABCA1 knockout mice and overexpression studies have established the importance of ABCA1 as a major determinant of HDL cholesterol in plasma. These studies also indicate that ABCA1 is critically involved in cellular trafficking of cholesterol and choline-phospholipids and in total body lipid homeostasis, such as intestinal cholesterol and fat-soluble vitamin absorption and in the modulation of steroidogenesis. First insights into the upregulation of ABCA1 gene expression by cellular cholesterol and cAMP have identified critical ABCA1 promoter elements, which bind the transcription factors liver X receptor, retinoid X receptor, Sp1 and E-box proteins. The finding that a lipid sensitive subgroup of ABC transporters is able to translocate cholesterol and phospholipids supports the concept that in ABCA1 deficiency, compensatory mechanisms possibly involving MDR1, MDR3 and MRP-family members could be active. This suggests that a network of ABC transporters involved in cellular lipid transport exists, which is under the tight control of energy pathways directly linked to high density lipoprotein metabolism and atherogenesis.
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Affiliation(s)
- G Schmitz
- Institute for Clinical Chemistry and Laboratory Medicine, University of Regensburg, Regensburg, Germany.
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