1
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Tang CY, Wang J, Liu X, Chen JB, Liang J, Wang T, Simpson WR, Li YL, Li XZ. Medium optimization for high mycelial soluble protein content of Ophiocordyceps sinensis using response surface methodology. Front Microbiol 2022; 13:1055055. [PMID: 36569047 PMCID: PMC9780674 DOI: 10.3389/fmicb.2022.1055055] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Accepted: 11/23/2022] [Indexed: 12/13/2022] Open
Abstract
Ophiocordyceps sinensis is widely utilized due to its pharmaceutical value. Mycelial protein forms a key active component of O. sinensis and determines the medicinal potential of fungus. Here, we describe the development of an optimized fermentation medium to obtain more mycelial soluble protein from O. sinensis using response surface methodology (RSM) and investigate the increased mycelial protein content using transcriptomics. The maximum mycelial protein content of 2.11% was obtained using a medium consisting of 20% beef broth, 0.10% peptone, 2% glucose, 0.15% yeast extract, 0.20% KH2PO4, and 0.02% MgSO4. Transcriptome analysis identified 790 differentially expressed genes (DEGs), including 592 up-regulated genes and 198 down-regulated genes, optimisation resulted in more up-regulated genes. The main DEGs were enriched in metabolic pathways, ABC transporters, starch and sucrose metabolism, tyrosine metabolism, and glutathione metabolism. In addition, some DEGs associated with mycelial protein enhancement such as tyrosinase (TYR), glutathione S-transferase (GST), glutamine synthetase (glnA), and β-glucosidase may contribute to increased mycelial protein content. Real-time quantitative PCR (RT-qPCR) was used to confirm gene expression and the results support the accuracy of RNA-Seq and DEG analysis. This study provides an optimized fermentation method for enhancing the mycelial protein content of O. sinensis and a reference for the effective development of O. sinensis protein.
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Affiliation(s)
- Chu-Yu Tang
- State Key Laboratory of Plateau Ecology and Agriculture, Qinghai Academy of Animal and Veterinary Sciences, Qinghai University, Xining, China
| | - Jie Wang
- State Key Laboratory of Plateau Ecology and Agriculture, Qinghai Academy of Animal and Veterinary Sciences, Qinghai University, Xining, China
| | - Xin Liu
- State Key Laboratory of Plateau Ecology and Agriculture, Qinghai Academy of Animal and Veterinary Sciences, Qinghai University, Xining, China
| | - Jian-Bo Chen
- State Key Laboratory of Plateau Ecology and Agriculture, Qinghai Academy of Animal and Veterinary Sciences, Qinghai University, Xining, China
| | - Jing Liang
- State Key Laboratory of Plateau Ecology and Agriculture, Qinghai Academy of Animal and Veterinary Sciences, Qinghai University, Xining, China
| | - Tao Wang
- State Key Laboratory of Plateau Ecology and Agriculture, Qinghai Academy of Animal and Veterinary Sciences, Qinghai University, Xining, China
| | | | - Yu-Ling Li
- State Key Laboratory of Plateau Ecology and Agriculture, Qinghai Academy of Animal and Veterinary Sciences, Qinghai University, Xining, China,*Correspondence: Yu-Ling Li,
| | - Xiu-Zhang Li
- State Key Laboratory of Plateau Ecology and Agriculture, Qinghai Academy of Animal and Veterinary Sciences, Qinghai University, Xining, China,Xiu-Zhang Li,
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2
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Elejalde-Palmett C, Martinez San Segundo I, Garroum I, Charrier L, De Bellis D, Mucciolo A, Guerault A, Liu J, Zeisler-Diehl V, Aharoni A, Schreiber L, Bakan B, Clausen MH, Geisler M, Nawrath C. ABCG transporters export cutin precursors for the formation of the plant cuticle. Curr Biol 2021; 31:2111-2123.e9. [PMID: 33756108 DOI: 10.1016/j.cub.2021.02.056] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Revised: 01/14/2021] [Accepted: 02/25/2021] [Indexed: 02/07/2023]
Abstract
The plant cuticle is deposited on the surface of primary plant organs, such as leaves, fruits, and floral organs, forming a diffusion barrier and protecting the plant against various abiotic and biotic stresses. Cutin, the structural polyester of the plant cuticle, is synthesized in the apoplast. Plasma-membrane-localized ATP-binding cassette (ABC) transporters of the G family have been hypothesized to export cutin precursors. Here, we characterize SlABCG42 of tomato representing an ortholog of AtABCG32 in Arabidopsis. SlABCG42 expression in Arabidopsis complements the cuticular deficiencies of the Arabidopsis pec1/abcg32 mutant. RNAi-dependent downregulation of both tomato genes encoding proteins highly homologous to AtABCG32 (SlABCG36 and SlABCG42) leads to reduced cutin deposition and formation of a thinner cuticle in tomato fruits. By using a tobacco (Nicotiana benthamiana) protoplast system, we show that AtABCG32 and SlABCG42 have an export activity for 10,16-dihydroxy hexadecanoyl-2-glycerol, a cutin precursor in vivo. Interestingly, also free ω-hydroxy hexadecanoic acid as well as hexadecanedioic acid were exported, furthering the research on the identification of cutin precursors in vivo and the respective mechanisms of their integration into the cutin polymer.
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Affiliation(s)
| | - Ignacio Martinez San Segundo
- Center for Nanomedicine and Theranostics, Department of Chemistry, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark
| | - Imène Garroum
- Department of Plant Molecular Biology, University of Lausanne, 1015 Lausanne, Switzerland
| | - Laurence Charrier
- Department of Biology, University of Fribourg, 1700 Fribourg, Switzerland
| | - Damien De Bellis
- Department of Plant Molecular Biology, University of Lausanne, 1015 Lausanne, Switzerland; Electron Microscopy Facility, University of Lausanne, 1015 Lausanne, Switzerland
| | - Antonio Mucciolo
- Electron Microscopy Facility, University of Lausanne, 1015 Lausanne, Switzerland
| | - Aurore Guerault
- Department of Plant Molecular Biology, University of Lausanne, 1015 Lausanne, Switzerland
| | - Jie Liu
- Department of Biology, University of Fribourg, 1700 Fribourg, Switzerland
| | | | - Asaph Aharoni
- Department of Plant Sciences, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Lukas Schreiber
- Institute of Cellular and Molecular Botany, University of Bonn, 53115 Bonn, Germany
| | - Bénédicte Bakan
- INRAE, Biopolymers Interactions Assemblies UR1268, 44316 Nantes Cedex 3, France
| | - Mads H Clausen
- Center for Nanomedicine and Theranostics, Department of Chemistry, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark
| | - Markus Geisler
- Department of Biology, University of Fribourg, 1700 Fribourg, Switzerland
| | - Christiane Nawrath
- Department of Plant Molecular Biology, University of Lausanne, 1015 Lausanne, Switzerland.
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3
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He J, Han Z, Farooq QUA, Li C. Study on functional sites in human multidrug resistance protein 1 (hMRP1). Proteins 2021; 89:659-670. [PMID: 33469960 DOI: 10.1002/prot.26049] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 11/22/2020] [Accepted: 12/27/2020] [Indexed: 01/27/2023]
Abstract
Human multidrug resistance protein 1 (hMRP1) is an important member of the ATP-binding cassette (ABC) transporter superfamily. It can extrude a variety of anticancer drugs and physiological organic anions across the plasma membrane, which is activated by substrate binding, and is accompanied by large-scale cooperative movements between different domains. Currently, it remains unclear completely about how the specific interactions between hMRP1 and its substrate are and which critical residues are responsible for allosteric signal transduction. To the end, we first construct an inward-facing state of hMRP1 using homology modeling method, and then dock substrate proinflammatory agent leukotriene C4 (LTC4) to hMRP1 pocket. The result manifests LTC4 interacts with two parts of hMRP1 pocket, namely the positively charged pocket (P pocket) and hydrophobic pocket (H pocket), similar to its binding mode with bMRP1 (bovine MRP1). Additionally, we use the Gaussian network model (GNM)-based thermodynamic method proposed by us to identify the key residues whose perturbations markedly alter their binding free energy. Here the conventional GNM is improved with covalent/non-covalent interactions and secondary structure information considered (denoted as sscGNM). In the result, sscGNM improves the flexibility prediction, especially for the nucleotide binding domains with rich kinds of secondary structures. The 46 key residue clusters located in different subdomains are identified which are highly consistent with experimental observations. Furtherly, we explore the long-range cooperation within the transporter. This study is helpful for strengthening the understanding of the work mechanism in ABC exporters and can provide important information to scientists in drug design studies.
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Affiliation(s)
- Junmei He
- Faculty of Environmental and Life Sciences, Beijing University of Technology, Beijing, China
| | - Zhongjie Han
- Faculty of Environmental and Life Sciences, Beijing University of Technology, Beijing, China
| | - Qurat Ul Ain Farooq
- Faculty of Environmental and Life Sciences, Beijing University of Technology, Beijing, China
| | - Chunhua Li
- Faculty of Environmental and Life Sciences, Beijing University of Technology, Beijing, China
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4
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Kadioglu O, Saeed MEM, Munder M, Spuller A, Greten HJ, Efferth T. Effect of ABC transporter expression and mutational status on survival rates of cancer patients. Biomed Pharmacother 2020; 131:110718. [PMID: 32932043 DOI: 10.1016/j.biopha.2020.110718] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Revised: 08/28/2020] [Accepted: 08/30/2020] [Indexed: 02/07/2023] Open
Abstract
ATP-binding cassette (ABC) transporters mediate multidrug resistance in cancer. In contrast to DNA single nucleotide polymorphisms in normal tissues, the role of mutations in tumors is unknown. Furthermore, the significance of their expression for prediction of chemoresistance and survival prognosis is still under debate. We investigated 18 tumors by RNA-sequencing. The mutation rate varied from 27,507 to 300885. In ABCB1, three hotspots with novel mutations were in transmembrane domains 3, 8, and 9. We also mined the cBioPortal database with 11,814 patients from 23 different tumor entities. We performed Kaplan-Meier survival analyses to investigate the effect of ABC transporter expression on survival rates of cancer patients. Novel mutations were also found in ABCA2, ABCA3, ABCB2, ABCB5, ABCC1-6, and ABCG2. Mining the cBioPortal database with 11,814 patients from 23 different tumor entities validated our results. Missense and in-frame mutations led to altered binding of anticancer drugs in molecular docking approaches. The ABCB1 nonsense mutation Q856* led to a truncated P-glycoprotein, which may sensitize tumors to anticancer drugs. The search for ABC transporter nonsense mutations represents a novel approach for precision medicine.. Low ABCB1 mRNA expression correlated with significantly longer survival in ovarian or kidney cancer and thymoma. In cancers of breast, kidney or lung, ABC transporter expression correlated with different tumor stages and human populations as further parameters to refine strategies for more individualized chemotherapy.
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Affiliation(s)
- Onat Kadioglu
- Department of Pharmaceutical Biology, Institute of Pharmaceutical and Biomedical Sciences, Johannes Gutenberg University, Mainz, Germany
| | - Mohamed E M Saeed
- Department of Pharmaceutical Biology, Institute of Pharmaceutical and Biomedical Sciences, Johannes Gutenberg University, Mainz, Germany
| | - Markus Munder
- Department of Medicine (Hematology, Oncology, and Pneumology), University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | | | - Henry Johannes Greten
- Abel Salazar Biomedical Sciences Institute, University of Porto, Portugal; Heidelberg School of Chinese Medicine, Heidelberg, Germany
| | - Thomas Efferth
- Department of Pharmaceutical Biology, Institute of Pharmaceutical and Biomedical Sciences, Johannes Gutenberg University, Mainz, Germany.
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5
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Kumar P, Devaki B, Jonnala UK, Amere Subbarao S. Hsp90 facilitates acquired drug resistance of tumor cells through cholesterol modulation however independent of tumor progression. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2020; 1867:118728. [PMID: 32343987 DOI: 10.1016/j.bbamcr.2020.118728] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Revised: 04/11/2020] [Accepted: 04/19/2020] [Indexed: 12/23/2022]
Abstract
Acquired multidrug resistance of cancer cells challenges the chemotherapeutic interventions. To understand the role of molecular chaperone, Hsp90 in drug adapted tumor cells, we have used in vitro drug adapted epidermoid tumor cells as a model system. We found that chemotherapeutic drug adaptation of tumor cells is mediated by induced activities of both Hsp90 and P-glycoprotein (P-gp). Although the high-affinity conformation of Hsp90 has correlated with the enhanced drug efflux activity, we did not observe a direct interaction between P-gp and Hsp90. The enrichment of P-gp and Hsp90 at the cholesterol-rich membrane microdomains is found obligatory for enhanced drug efflux activity. Since inhibition of cholesterol biosynthesis is not interfering with the drug efflux activity, it is presumed that the net cholesterol redistribution mediated by Hsp90 regulates the enhanced drug efflux activity. Our in vitro cholesterol and Hsp90 interaction studies have furthered our presumption that Hsp90 facilitates cholesterol redistribution. The drug adapted cells though exhibited anti-proliferative and anti-tumor effects in response to 17AAG treatment, drug treatment has also enhanced the drug efflux activity. Our findings suggest that drug efflux activity and metastatic potential of tumor cells are independently regulated by Hsp90 by distinct mechanisms. We expose the limitations imposed by Hsp90 inhibitors against multidrug resistant tumor cells.
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Affiliation(s)
- Pankaj Kumar
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, Telangana, India
| | - Bharath Devaki
- Presently at Department of Molecular & Cell Biology, University of Texas, Dallas, USA
| | - Ujwal Kumar Jonnala
- Presently at SYNGENE International Ltd., Biocon BMS R & D Centre, Bengaluru, Karnataka, India
| | - Sreedhar Amere Subbarao
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, Telangana, India.
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6
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Yaneff A, Sahores A, Gómez N, Carozzo A, Shayo C, Davio C. MRP4/ABCC4 As a New Therapeutic Target: Meta-Analysis to Determine cAMP Binding Sites as a Tool for Drug Design. Curr Med Chem 2019; 26:1270-1307. [PMID: 29284392 DOI: 10.2174/0929867325666171229133259] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2017] [Revised: 12/01/2017] [Accepted: 12/14/2017] [Indexed: 02/06/2023]
Abstract
MRP4 transports multiple endogenous and exogenous substances and is critical not only for detoxification but also in the homeostasis of several signaling molecules. Its dysregulation has been reported in numerous pathological disorders, thus MRP4 appears as an attractive therapeutic target. However, the efficacy of MRP4 inhibitors is still controversial. The design of specific pharmacological agents with the ability to selectively modulate the activity of this transporter or modify its affinity to certain substrates represents a challenge in current medicine and chemical biology. The first step in the long process of drug rational design is to identify the therapeutic target and characterize the mechanism by which it affects the given pathology. In order to develop a pharmacological agent with high specific activity, the second step is to systematically study the structure of the target and identify all the possible binding sites. Using available homology models and mutagenesis assays, in this review we recapitulate the up-to-date knowledge about MRP structure and aligned amino acid sequences to identify the candidate MRP4 residues where cyclic nucleotides bind. We have also listed the most relevant MRP inhibitors studied to date, considering drug safety and specificity for MRP4 in particular. This meta-analysis platform may serve as a basis for the future development of inhibitors of MRP4 cAMP specific transport.
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Affiliation(s)
- Agustín Yaneff
- Instituto de Investigaciones Farmacologicas (ININFA-UBA-CONICET), Facultad de Farmacia y Bioquimica, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Ana Sahores
- Instituto de Investigaciones Farmacologicas (ININFA-UBA-CONICET), Facultad de Farmacia y Bioquimica, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Natalia Gómez
- Instituto de Investigaciones Farmacologicas (ININFA-UBA-CONICET), Facultad de Farmacia y Bioquimica, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Alejandro Carozzo
- Instituto de Investigaciones Farmacologicas (ININFA-UBA-CONICET), Facultad de Farmacia y Bioquimica, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Carina Shayo
- Instituto de Biologia y Medicina Experimental (IBYME-CONICET), Buenos Aires, Argentina
| | - Carlos Davio
- Instituto de Investigaciones Farmacologicas (ININFA-UBA-CONICET), Facultad de Farmacia y Bioquimica, Universidad de Buenos Aires, Buenos Aires, Argentina
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7
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Mares L, Vilchis F, Chávez B, Ramos L. Isolation and sex steroid effects on the expression of the ATP-binding cassette transporter ABCB6 in Harderian glands of hamster (Mesocricetus auratus). Comp Biochem Physiol A Mol Integr Physiol 2019; 232:40-46. [PMID: 30878759 DOI: 10.1016/j.cbpa.2019.03.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Revised: 02/25/2019] [Accepted: 03/08/2019] [Indexed: 10/27/2022]
Abstract
ATP-Binding Cassette, subfamily B, member 6 (ABCB6) is a transporter that is upregulated by elevated intracellular porphyrin concentrations. In the Harderian gland (HG), the synthesis of porphyrins appears to be under the influence of gonadal steroids and to exhibit a dimorphic pattern. To explore whether ABCB6 is also influenced by sex steroids, we isolated its specific cDNA sequence and investigated its mRNA levels in the HGs of hamsters. ABCB6's cDNA sequence presents an open reading frame (ORF) of 2529 bp that encodes a predicted 842-amino acid (aa) protein with a molecular weight of 93 kDa. Multiple sequence alignments showed that ABCB6's aa sequence is highly conserved and shares the highest homology (93%) with mouse ABCB6. RT-qPCR analysis indicated that ABCB6 is expressed in all the tissues examined, exhibiting high expression levels in the liver, adrenal glands, and testis. The mRNA concentrations of ABCB6 in HGs were very similar between males and in females; similarly, gonadectomy and treatment with sex steroids appear to scarcely affect ABCB6 mRNA levels. The intraglandular content of ABCB6 mRNA showed discrete, though non-significant, variations through the estrous cycle. The results provide evidence that gonadal steroids have a minimal physiological role on the regulation of ABCB6 expression and might indicate that this transporter has a small effect on porphyrin trafficking in the HGs of hamsters.
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Affiliation(s)
- L Mares
- Department of Reproductive Biology, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, México City, México
| | - F Vilchis
- Department of Reproductive Biology, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, México City, México
| | - B Chávez
- Department of Reproductive Biology, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, México City, México
| | - L Ramos
- Department of Reproductive Biology, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, México City, México.
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8
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Zubiaur P, Saiz-Rodríguez M, Koller D, Ovejero-Benito MC, Wojnicz A, Abad-Santos F. How to make P-glycoprotein (ABCB1, MDR1) harbor mutations and measure its expression and activity in cell cultures? Pharmacogenomics 2018; 19:1285-1297. [PMID: 30334473 DOI: 10.2217/pgs-2018-0101] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Several polymorphisms have been identified in ABCB1, the gene encoding for the P-glycoprotein. This transporter alters the pharmacokinetics or effectiveness of drugs by excreting them from cells where it is expressed (e.g., blood-brain barrier, intestine or tumors). No consensus has been reached regarding the functional consequences of these polymorphisms in the transporter's function. The aim of this review was to describe a methodology that allows the assessment of P-gp function when harboring polymorphisms. We describe how to obtain cell lines with high expression levels of the transporter with polymorphisms and several tactics to measure its expression and activity. This methodology may help elucidate the contribution of polymorphisms in ABCB1 to drug pharmacokinetics, effectiveness and safety or to cancer chemotherapy failure.
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Affiliation(s)
- Pablo Zubiaur
- Clinical Pharmacology Department, Hospital Universitario de la Princesa, Instituto Teófilo Hernando, Universidad Autónoma de Madrid (UAM), Instituto de Investigación Sanitaria la Princesa (IP), Madrid, Spain
| | - Miriam Saiz-Rodríguez
- Clinical Pharmacology Department, Hospital Universitario de la Princesa, Instituto Teófilo Hernando, Universidad Autónoma de Madrid (UAM), Instituto de Investigación Sanitaria la Princesa (IP), Madrid, Spain
| | - Dora Koller
- Clinical Pharmacology Department, Hospital Universitario de la Princesa, Instituto Teófilo Hernando, Universidad Autónoma de Madrid (UAM), Instituto de Investigación Sanitaria la Princesa (IP), Madrid, Spain
| | - María Carmen Ovejero-Benito
- Clinical Pharmacology Department, Hospital Universitario de la Princesa, Instituto Teófilo Hernando, Universidad Autónoma de Madrid (UAM), Instituto de Investigación Sanitaria la Princesa (IP), Madrid, Spain
| | - Aneta Wojnicz
- Clinical Pharmacology Department, Hospital Universitario de la Princesa, Instituto Teófilo Hernando, Universidad Autónoma de Madrid (UAM), Instituto de Investigación Sanitaria la Princesa (IP), Madrid, Spain
| | - Francisco Abad-Santos
- Clinical Pharmacology Department, Hospital Universitario de la Princesa, Instituto Teófilo Hernando, Universidad Autónoma de Madrid (UAM), Instituto de Investigación Sanitaria la Princesa (IP), Madrid, Spain.,UICEC Hospital Universitario de la Princesa, Plataforma SCReN (Spanish Clinical Reseach Network), Instituto de Investigación Sanitaria la Princesa (IP), Madrid, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), Instituto de Salud Carlos III, Madrid, Spain
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9
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Yakusheva EN, Titov DS. Structure and Function of Multidrug Resistance Protein 1. BIOCHEMISTRY (MOSCOW) 2018; 83:907-929. [DOI: 10.1134/s0006297918080047] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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10
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Zhu Y, Chu SJ, Luo YL, Fu JY, Tang CY, Lu GH, Pang YJ, Wang XM, Yang RW, Qi JL, Yang YH. Involvement of LeMRP, an ATP-binding cassette transporter, in shikonin transport and biosynthesis in Lithospermum erythrorhizon. PLANT BIOLOGY (STUTTGART, GERMANY) 2018; 20:365-373. [PMID: 29139179 DOI: 10.1111/plb.12666] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2017] [Accepted: 11/08/2017] [Indexed: 06/07/2023]
Abstract
Shikonin and its derivatives are important medicinal secondary metabolites accumulating in roots of Lithospermum erythrorhizon. Although some membrane proteins have been identified as transporters of secondary metabolites, the mechanisms underlying shikonin transport and accumulation in L. erythrorhizon cells still remain largely unknown. In this study, we isolated a cDNA encoding LeMRP, an ATP-binding cassette transporter from L. erythrorhizon, and further investigated its functions in the transport and biosynthesis of shikonin using the yeast transformation and transgenic hairy root methods, respectively. Real-time PCR was applied for expression analyses of LeMRP and shikonin biosynthetic enzyme genes. Functional analysis of LeMRP using the heterologous yeast cell expression system showed that LeMRP could be involved in shikonin transport. Transgenic hairy roots of L. erythrorhizon demonstrated that LeMRP overexpressing hairy roots produced more shikonin than the empty vector (EV) control. Real-time PCR results revealed that the enhanced shikonin biosynthesis in the overexpression lines was mainly caused by highly up-regulated expression of genes coding key enzymes (LePAL, HMGR, Le4CL and LePGT) involved in shikonin biosynthesis. Conversely, LeMRP RNAi decreased the accumulation of shikonin and effectively down-regulated expression level of the above genes. Typical inhibitors of ABC proteins, such as azide and buthionine sulphoximine, dramatically inhibited accumulation of shikonin in hairy roots. Our findings provide evidence for the important direct or indirect role of LeMRP in transmembrane transport and biosynthesis of shikonin.
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Affiliation(s)
- Y Zhu
- Institute of Plant Molecular Biology, State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, China
- Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, China
| | - S-J Chu
- Institute of Plant Molecular Biology, State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, China
- Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, China
| | - Y-L Luo
- Institute of Plant Molecular Biology, State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, China
- Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, China
| | - J-Y Fu
- Institute of Plant Molecular Biology, State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, China
- Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, China
| | - C-Y Tang
- Institute of Plant Molecular Biology, State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, China
- Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, China
| | - G-H Lu
- Institute of Plant Molecular Biology, State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, China
- Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, China
| | - Y-J Pang
- Institute of Plant Molecular Biology, State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, China
- Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, China
| | - X-M Wang
- Institute of Plant Molecular Biology, State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, China
- Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, China
| | - R-W Yang
- Institute of Plant Molecular Biology, State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, China
- Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, China
| | - J-L Qi
- Institute of Plant Molecular Biology, State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, China
- Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, China
| | - Y-H Yang
- Institute of Plant Molecular Biology, State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, China
- Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, China
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11
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Fu ZY. Role of ATP-binding cassette transporters, apoptosis, and long non-coding RNAs in gastric cancer multidrug resistance. Shijie Huaren Xiaohua Zazhi 2017; 25:2838-2850. [DOI: 10.11569/wcjd.v25.i32.2838] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Cancer multidrug resistance refers to the cross resistance of cancer cells to a variety of anticancer drugs, which can be primary or secondary. Several mechanisms attribute to cancer multidrug resistance. In this paper, the recent progress in the understanding of the mechanisms of multi-drug resistance of gastric cancer cells with regard to the role of adenosine triphosphate binding cassette transporters, apoptosis, and long non-coding RNAs is reviewed.
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Affiliation(s)
- Zhao-Ying Fu
- Institute of Molecular Biology and Immunology, Medical School of Yan'an University, Yan'an 716000, Shaanxi Province, China
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12
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Hong M. Biochemical studies on the structure-function relationship of major drug transporters in the ATP-binding cassette family and solute carrier family. Adv Drug Deliv Rev 2017; 116:3-20. [PMID: 27317853 DOI: 10.1016/j.addr.2016.06.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Revised: 05/27/2016] [Accepted: 06/08/2016] [Indexed: 12/21/2022]
Abstract
Human drug transporters often play key roles in determining drug accumulation within cells. Their activities are often directly related to therapeutic efficacy, drug toxicity as well as drug-drug interactions. However, the progress for interpretation of their crystal structures is relatively slow. Hence, conventional biochemical studies together with computer modeling became useful manners to reveal essential structures of these membrane proteins. Over the years, quite a few structure-function relationship information had been obtained for members of the two major transporter families: the ATP-binding cassette family and the solute carrier family. Critical structural features of drug transporters include transmembrane domains, post-translational modification sites and domains for cell surface assembly and protein-protein interactions. Alterations at these important sites may affect protein stability, trafficking to the plasma membrane and/or ability of transporters to interact with substrates.
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13
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Overcoming ABC transporter-mediated multidrug resistance: Molecular mechanisms and novel therapeutic drug strategies. Drug Resist Updat 2016; 27:14-29. [DOI: 10.1016/j.drup.2016.05.001] [Citation(s) in RCA: 452] [Impact Index Per Article: 56.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2015] [Revised: 04/24/2016] [Accepted: 05/06/2016] [Indexed: 12/15/2022]
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14
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Wang WJ, Sui H, Qi C, Li Q, Zhang J, Wu SF, Mei MZ, Lu YY, Wan YT, Chang H, Guo PT. Ursolic acid inhibits proliferation and reverses drug resistance of ovarian cancer stem cells by downregulating ABCG2 through suppressing the expression of hypoxia-inducible factor-1α in vitro. Oncol Rep 2016; 36:428-40. [PMID: 27221674 DOI: 10.3892/or.2016.4813] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Accepted: 02/14/2016] [Indexed: 11/06/2022] Open
Abstract
Hypoxia in tumors is closely related to drug resistance. It has not been verified whether hypoxia-inducible factor-1α (HIF-1α) or ABCG2 is related to hypoxia-induced resistance. Ursolic acid (UA), when used in combination with cisplatin can significantly increase the sensitivity of ovarian cancer stem cells (CSCs) to cisplatin, but the exact mechanism is unknown. The cell growth inhibitory rate of cisplatin under different conditions was evaluated using Cell Counting Kit-8 (CCK-8) in adherence and sphere cells (SKOV3, A2780, and HEY). The expression of HIF-1α and ABCG2 was tested using quantitative PCR, western blotting, and immuno-fluorescence under different culture conditions and treated with UA. Knockdown of HIF-1α by shRNA and LY294002 was used to inhibit the activity of PI3K/Akt pathway. Ovarian CSCs express stemness-related genes and drug resistance significantly higher than normal adherent cells. Under hypoxic conditions, the ovarian CSCs grew faster and were more drug resistant than under normoxia. UA could inhibit proliferation and reverse the drug resistance of ovarian CSC by suppressing ABCG2 and HIF-1α under different culture conditions. HIF-1α inhibitor YC-1 combined with UA suppressed the stemness genes and ABCG2 under hypoxic condition. The PI3K/Akt signaling pathway activation plays an important functional role in UA-induced downregulation of HIF-1α and reduction of ABCG2. UA inhibits the proliferation and reversal of drug resistance in ovarian CSCs by suppressing the expression of downregulation of HIF-1α and ABCG2.
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Affiliation(s)
- Wen-Jing Wang
- Department of Gynecology, Shuguang Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, P.R. China
| | - Hua Sui
- Department of Medical Oncology, Shuguang Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, P.R. China
| | - Cong Qi
- Department of Gynecology, Shuguang Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, P.R. China
| | - Qi Li
- Department of Medical Oncology, Shuguang Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, P.R. China
| | - Jie Zhang
- Department of Science and Technology, Longhua Hospital Affiliated to Shanghai University of Traditional Chinese Medicine, Shanghai 200032, P.R. China
| | - Shao-Fei Wu
- Department of Hepatopathy, Shandong Provincial Qianfoshan Hospital, Shandong University, Jinan, Shandong 250014, P.R. China
| | - Ming-Zhu Mei
- Department of Medical Oncology, Shuguang Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, P.R. China
| | - Ying-Yu Lu
- Department of Gynecology, Shuguang Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, P.R. China
| | - Yi-Ting Wan
- Department of Gynecology, Shuguang Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, P.R. China
| | - Hannah Chang
- Department of Gynecology, Shuguang Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, P.R. China
| | - Piao-Ting Guo
- Department of Medical Oncology, Shanghai General Hospital, Shanghai 201203, P.R. China
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15
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Tulsyan S, Mittal RD, Mittal B. The effect of ABCB1 polymorphisms on the outcome of breast cancer treatment. PHARMACOGENOMICS & PERSONALIZED MEDICINE 2016; 9:47-58. [PMID: 27175090 PMCID: PMC4854269 DOI: 10.2147/pgpm.s86672] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The ABCB1 gene encodes a permeability glycoprotein, which is one of the most extensively studied human adenosine-triphosphate (ATP)-dependent efflux transporters. Permeability glycoprotein is expressed in the apical membranes of tissues such as intestine, liver, blood–brain barrier, kidney, placenta, and testis and contributes to intracellular drug disposition. It is also highly expressed in tumor cells conferring drug resistance, which is one of the major problems in the efficacy of cancer chemotherapy treatment. ABCB1 is highly polymorphic, and three well-known single-nucleotide polymorphisms such as 1236C>T, 2677G>T/A, and 3435C>T have been found to be associated with altered messenger RNA levels, protein folding, and drug pharmacokinetics. Many association studies and meta-analyses have demonstrated the clinical impact of ABCB1 polymorphisms in breast cancer treatment outcomes with respect to therapeutic response, chemotoxicity, and overall survival. Therefore, the aim of this review was to evaluate the effects of ABCB1 polymorphisms on the outcome of breast cancer treatment which, in future, would be important for tailoring individualized anticancer therapy.
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Affiliation(s)
- Sonam Tulsyan
- Department of Genetics, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, India
| | - Rama Devi Mittal
- Department of Urology and Renal Transplant, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, India
| | - Balraj Mittal
- Department of Genetics, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, India
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16
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A single active catalytic site is sufficient to promote transport in P-glycoprotein. Sci Rep 2016; 6:24810. [PMID: 27117502 PMCID: PMC4846820 DOI: 10.1038/srep24810] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Accepted: 04/05/2016] [Indexed: 11/23/2022] Open
Abstract
P-glycoprotein (Pgp) is an ABC transporter responsible for the ATP-dependent efflux of chemotherapeutic compounds from multidrug resistant cancer cells. Better understanding of the molecular mechanism of Pgp-mediated transport could promote rational drug design to circumvent multidrug resistance. By measuring drug binding affinity and reactivity to a conformation-sensitive antibody we show here that nucleotide binding drives Pgp from a high to a low substrate-affinity state and this switch coincides with the flip from the inward- to the outward-facing conformation. Furthermore, the outward-facing conformation survives ATP hydrolysis: the post-hydrolytic complex is stabilized by vanadate, and the slow recovery from this state requires two functional catalytic sites. The catalytically inactive double Walker A mutant is stabilized in a high substrate affinity inward-open conformation, but mutants with one intact catalytic center preserve their ability to hydrolyze ATP and to promote drug transport, suggesting that the two catalytic sites are randomly recruited for ATP hydrolysis.
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17
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Pleiotropic effects of the vacuolar ABC transporter MLT1 of Candida albicans on cell function and virulence. Biochem J 2016; 473:1537-52. [PMID: 27026051 PMCID: PMC4888455 DOI: 10.1042/bcj20160024] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Accepted: 03/29/2016] [Indexed: 01/14/2023]
Abstract
Among the several mechanisms that contribute to MDR (multidrug resistance), the overexpression of drug-efflux pumps belonging to the ABC (ATP-binding cassette) superfamily is the most frequent cause of resistance to antifungal agents. The multidrug transporter proteins Cdr1p and Cdr2p of the ABCG subfamily are major players in the development of MDR in Candida albicans. Because several genes coding for ABC proteins exist in the genome of C. albicans, but only Cdr1p and Cdr2p have established roles in MDR, it is implicit that the other members of the ABC family also have alternative physiological roles. The present study focuses on an ABC transporter of C. albicans, Mlt1p, which is localized in the vacuolar membrane and specifically transports PC (phosphatidylcholine) into the vacuolar lumen. Transcriptional profiling of the mlt1∆/∆ mutant revealed a down-regulation of the genes involved in endocytosis, oxidoreductase activity, virulence and hyphal development. High-throughput MS-based lipidome analysis revealed that the Mlt1p levels affect lipid homoeostasis and thus lead to a plethora of physiological perturbations. These include a delay in endocytosis, inefficient sequestering of reactive oxygen species (ROS), defects in hyphal development and attenuated virulence. The present study is an emerging example where new and unconventional roles of an ABC transporter are being identified.
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18
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Splice form variant and amino acid changes in MDR49 confers DDT resistance in transgenic Drosophila. Sci Rep 2016; 6:23355. [PMID: 27003579 PMCID: PMC4802207 DOI: 10.1038/srep23355] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Accepted: 03/04/2016] [Indexed: 01/27/2023] Open
Abstract
The ATP-binding cassette (ABC) transporters represent a superfamily of proteins that have important physiological roles in both prokaryotes and eukaryotes. In insects, ABC transporters have previously been implicated in insecticide resistance. The 91-R strain of Drosophila melanogaster has been intensely selected with DDT over six decades. A recent selective sweeps analysis of 91-R implicated the potential role of MDR49, an ABC transporter, in DDT resistance, however, to date the details of how MDR49 may play a role in resistance have not been elucidated. In this study, we investigated the impact of structural changes and an alternative splicing event in MDR49 on DDT-resistance in 91-R, as compared to the DDT susceptible strain 91-C. We observed three amino acid differences in MDR49 when 91-R was compared with 91-C, and only one isoform (MDR49B) was implicated in DDT resistance. A transgenic Drosophila strain containing the 91-R-MDR49B isoform had a significantly higher LD50 value as compared to the 91-C-MDR49B isoform at the early time points (6 h to 12 h) during DDT exposure. Our data support the hypothesis that the MDR49B isoform, with three amino acid mutations, plays a role in the early aspects of DDT resistance in 91-R.
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19
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Lu X, Long Y, Sun R, Zhou B, Lin L, Zhong S, Cui Z. Zebrafish Abcb4 is a potential efflux transporter of microcystin-LR. Comp Biochem Physiol C Toxicol Pharmacol 2015; 167:35-42. [PMID: 25193616 DOI: 10.1016/j.cbpc.2014.08.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Revised: 08/19/2014] [Accepted: 08/21/2014] [Indexed: 11/15/2022]
Abstract
Microcystin-LR (MC-LR) is one of the most common microcystins (MCs), which are hepatotoxic and released into a water body during a period of cyanobacterial blooms. These toxicants can be accumulated in aquatic animals and transferred along the food chain and thus pose adverse effects on aquatic environment and public health. Zebrafish Abcb4 is reported to mediate the cellular efflux of ecotoxicologically relevant compounds including galaxolide, tonalide and phenanthrene; however, it remains unclear whether Abcb4 functions in the detoxification of MC-LR. Here, we demonstrated the role of zebrafish Abcb4 in cellular efflux of MC-LR. Transcripts of zebrafish abcb4 were detected in all of adult tissues examined. MC-LR was able to induce the expression of abcb4 gene and overexpression of Abcb4 significantly decreased the cytotoxicity and accumulation of MC-LR in LLC-PK1 cells and developing embryos. In contrast, overexpression of an Abcb4-G1177D mutant abolished its transporter function but not substrate binding activity, and sensitized LLC-PK1 cells and developing embryos to this cyanobacterial toxin. Moreover, ATPase activity in developing embryos can be induced by MC-LR. Thus, zebrafish Abcb4 plays crucial roles in cellular efflux of MC-LR and is a potential molecular marker for the monitoring of cyanobacteria contamination in the aquatic environment.
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Affiliation(s)
- Xing Lu
- Department of Genetics, School of Basic Medical Science, Wuhan University, Wuhan 430071, Hubei, China.
| | - Yong Long
- The Key Laboratory of Aquatic Biodiversity and Conservation of Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, Hubei, China.
| | - Rongze Sun
- Department of Genetics, School of Basic Medical Science, Wuhan University, Wuhan 430071, Hubei, China.
| | - Bolan Zhou
- The Key Laboratory of Aquatic Biodiversity and Conservation of Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, Hubei, China.
| | - Li Lin
- Department of Genetics, School of Basic Medical Science, Wuhan University, Wuhan 430071, Hubei, China.
| | - Shan Zhong
- Department of Genetics, School of Basic Medical Science, Wuhan University, Wuhan 430071, Hubei, China.
| | - Zongbin Cui
- The Key Laboratory of Aquatic Biodiversity and Conservation of Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, Hubei, China.
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20
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Lu X, Long Y, Lin L, Sun R, Zhong S, Cui Z. Characterization of zebrafish Abcc4 as an efflux transporter of organochlorine pesticides. PLoS One 2014; 9:e111664. [PMID: 25478949 PMCID: PMC4257548 DOI: 10.1371/journal.pone.0111664] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2014] [Accepted: 09/29/2014] [Indexed: 11/18/2022] Open
Abstract
DDT and lindane are highly toxic organochlorine pesticides and posing adverse effects on the environment and public health due to their frequent usage in developing countries. ABCC4/MRP4 is an organic anion transporter that mediates cellular efflux of a wide range of exogenous and endogenous compounds such as cyclic nucleotides and anti-cancer drugs; however, it remains unclear whether ABCC4 and its orthologs function in the detoxification of organochlorine pesticides. Here, we demonstrated the roles of zebrafish Abcc4 in cellular efflux of DDT and lindane. Zebrafish abcc4 was maternally expressed in the oocytes and its transcripts were detected in the lens, pancreas, gills, liver, intestine and bladder of developing embryos and in adult tissues examined. DDT and lindane were able to induce the expression of abcc4 gene and overexpression of Abcc4 significantly decreased the cytotoxicity and accumulation of DDT and lindane in LLC-PK1 cells and developing embryos. In contrast, overexpression of an Abcc4-G1188D mutant abolished its transporter function without effects on its substrate binding activity, and sensitized LLC-PK1 cells and developing embryos to toxic pesticides. Moreover, glutathione (GSH) was involved in the efflux of cellular pesticides and ATPase activity in developing embryos can be induced by DDT or lindane. Thus, zebrafish Abcc4 plays crucial roles in cellular efflux of organochlorine pesticides and can be used a potential molecular marker for the monitor of DDT and lindane contamination in the aquatic environment.
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Affiliation(s)
- Xing Lu
- Department of Genetics, School of Basic Medical Science, Wuhan University, Wuhan, Hubei, China
| | - Yong Long
- The Key Laboratory of Aquatic Biodiversity and Conservation of Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei, China
| | - Li Lin
- Department of Genetics, School of Basic Medical Science, Wuhan University, Wuhan, Hubei, China
| | - Rongze Sun
- Department of Genetics, School of Basic Medical Science, Wuhan University, Wuhan, Hubei, China
| | - Shan Zhong
- Department of Genetics, School of Basic Medical Science, Wuhan University, Wuhan, Hubei, China
- * E-mail: (SZ); (ZC)
| | - Zongbin Cui
- The Key Laboratory of Aquatic Biodiversity and Conservation of Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei, China
- * E-mail: (SZ); (ZC)
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21
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Silva R, Vilas-Boas V, Carmo H, Dinis-Oliveira RJ, Carvalho F, de Lourdes Bastos M, Remião F. Modulation of P-glycoprotein efflux pump: induction and activation as a therapeutic strategy. Pharmacol Ther 2014; 149:1-123. [PMID: 25435018 DOI: 10.1016/j.pharmthera.2014.11.013] [Citation(s) in RCA: 231] [Impact Index Per Article: 23.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2014] [Accepted: 11/19/2014] [Indexed: 01/03/2023]
Abstract
P-glycoprotein (P-gp) is an ATP-dependent efflux pump encoded by the MDR1 gene in humans, known to mediate multidrug resistance of neoplastic cells to cancer therapy. For several decades, P-gp inhibition has drawn many significant research efforts in an attempt to overcome this phenomenon. However, P-gp is also constitutively expressed in normal human epithelial tissues and, due to its broad substrate specificity, to its cellular polarized expression in many excretory and barrier tissues, and to its great efflux capacity, it can play a crucial role in limiting the absorption and distribution of harmful xenobiotics, by decreasing their intracellular accumulation. Such a defense mechanism can be of particular relevance at the intestinal level, by significantly reducing the intestinal absorption of the xenobiotic and, consequently, avoiding its access to the target organs. In this review, the current knowledge on this important efflux pump is summarized, and a new focus is brought on the therapeutic interest of inducing and/or activating P-gp for limiting the toxicity caused by its substrates. Several in vivo and in vitro studies validating the use of such a therapeutic strategy are discussed. An extensive literature search for reported P-gp inducers/activators and for the experimental models used in their characterization was conducted. Those studies demonstrate that effective antidotal pathways can be achieved by efficiently promoting the P-gp-mediated efflux of deleterious xenobiotics, resulting in a significant reduction in their intracellular levels and, consequently, in a significant reduction of their toxicity.
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Affiliation(s)
- Renata Silva
- UCIBIO-REQUIMTE, Laboratory of Toxicology, Biological Sciences Department, Faculty of Pharmacy, University of Porto, Rua de Jorge Viterbo Ferreira, 228, 4050-313 Porto, Portugal.
| | - Vânia Vilas-Boas
- UCIBIO-REQUIMTE, Laboratory of Toxicology, Biological Sciences Department, Faculty of Pharmacy, University of Porto, Rua de Jorge Viterbo Ferreira, 228, 4050-313 Porto, Portugal.
| | - Helena Carmo
- UCIBIO-REQUIMTE, Laboratory of Toxicology, Biological Sciences Department, Faculty of Pharmacy, University of Porto, Rua de Jorge Viterbo Ferreira, 228, 4050-313 Porto, Portugal.
| | - Ricardo Jorge Dinis-Oliveira
- UCIBIO-REQUIMTE, Laboratory of Toxicology, Biological Sciences Department, Faculty of Pharmacy, University of Porto, Rua de Jorge Viterbo Ferreira, 228, 4050-313 Porto, Portugal; INFACTS - Institute of Research and Advanced Training in Health Sciences and Technologies, Department of Sciences, Advanced Institute of Health Sciences - North (ISCS-N), CESPU, CRL, Gandra, Portugal; Department of Legal Medicine and Forensic Sciences, Faculty of Medicine, University of Porto, Porto, Portugal.
| | - Félix Carvalho
- UCIBIO-REQUIMTE, Laboratory of Toxicology, Biological Sciences Department, Faculty of Pharmacy, University of Porto, Rua de Jorge Viterbo Ferreira, 228, 4050-313 Porto, Portugal.
| | - Maria de Lourdes Bastos
- UCIBIO-REQUIMTE, Laboratory of Toxicology, Biological Sciences Department, Faculty of Pharmacy, University of Porto, Rua de Jorge Viterbo Ferreira, 228, 4050-313 Porto, Portugal.
| | - Fernando Remião
- UCIBIO-REQUIMTE, Laboratory of Toxicology, Biological Sciences Department, Faculty of Pharmacy, University of Porto, Rua de Jorge Viterbo Ferreira, 228, 4050-313 Porto, Portugal.
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22
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Miranda ER, Nam EA, Kuspa A, Shaulsky G. The ABC transporter, AbcB3, mediates cAMP export in D. discoideum development. Dev Biol 2014; 397:203-11. [PMID: 25448698 DOI: 10.1016/j.ydbio.2014.11.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Revised: 10/15/2014] [Accepted: 11/11/2014] [Indexed: 11/24/2022]
Abstract
Extracellular cAMP functions as a primary ligand for cell surface cAMP receptors throughout Dictyostelium discoideum development, controlling chemotaxis and morphogenesis. The developmental consequences of cAMP signaling and the metabolism of cAMP have been studied in great detail, but it has been unclear how cells export cAMP across the plasma membrane. Here we show pharmacologically and genetically that ABC transporters mediate cAMP export. Using an evolutionary-developmental biology approach, we identified several candidate abc genes and characterized one of them, abcB3, in more detail. Genetic and biochemical evidence suggest that AbcB3 is a component of the cAMP export mechanism in D. discoideum development.
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Affiliation(s)
- Edward Roshan Miranda
- Graduate Program in Developmental Biology, Baylor College of Medicine, Houston, TX 77030, USA; Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Edward A Nam
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Adam Kuspa
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Gad Shaulsky
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA.
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23
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de Marcos Lousa C, Dietrich D, Johnson B, Baldwin S, Holdsworth M, Theodoulou FL, Baker A. The NBDs that wouldn't die. Commun Integr Biol 2014. [DOI: 10.4161/cib.7621] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
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24
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Guinamard R, Hof T, Del Negro CA. The TRPM4 channel inhibitor 9-phenanthrol. Br J Pharmacol 2014; 171:1600-13. [PMID: 24433510 PMCID: PMC3966741 DOI: 10.1111/bph.12582] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2013] [Revised: 12/17/2013] [Accepted: 01/08/2014] [Indexed: 01/06/2023] Open
Abstract
The phenanthrene-derivative 9-phenanthrol is a recently identified inhibitor of the transient receptor potential melastatin (TRPM) 4 channel, a Ca(2+) -activated non-selective cation channel whose mechanism of action remains to be determined. Subsequent studies performed on other ion channels confirm the specificity of the drug for TRPM4. In addition, 9-phenanthrol modulates a variety of physiological processes through TRPM4 current inhibition and thus exerts beneficial effects in several pathological conditions. 9-Phenanthrol modulates smooth muscle contraction in bladder and cerebral arteries, affects spontaneous activity in neurons and in the heart, and reduces lipopolysaccharide-induced cell death. Among promising potential applications, 9-phenanthrol exerts cardioprotective effects against ischaemia-reperfusion injuries and reduces ischaemic stroke injuries. In addition to reviewing the biophysical effects of 9-phenanthrol, here we present information about its appropriate use in physiological studies and possible clinical applications.
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Affiliation(s)
- R Guinamard
- EA 4650, Groupe Signalisation, Electrophysiologie et Imagerie des Lésions d'Ischémie-Reperfusion Myocardique, UCBN, Normandie UniversitéCaen, France
- Department of Applied Science, The College of William and MaryWilliamsburg, VA, USA
| | - T Hof
- EA 4650, Groupe Signalisation, Electrophysiologie et Imagerie des Lésions d'Ischémie-Reperfusion Myocardique, UCBN, Normandie UniversitéCaen, France
| | - C A Del Negro
- Department of Applied Science, The College of William and MaryWilliamsburg, VA, USA
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25
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VanDuyn N, Nass R. The putative multidrug resistance protein MRP-7 inhibits methylmercury-associated animal toxicity and dopaminergic neurodegeneration in Caenorhabditis elegans. J Neurochem 2013; 128:962-74. [PMID: 24266639 DOI: 10.1111/jnc.12515] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2013] [Revised: 10/17/2013] [Accepted: 10/28/2013] [Indexed: 10/26/2022]
Abstract
Parkinson's disease (PD) is the most prevalent neurodegenerative motor disorder worldwide, and results in the progressive loss of dopamine (DA) neurons in the substantia nigra pars compacta. Gene-environment interactions are believed to play a significant role in the vast majority of PD cases, yet the toxicants and the associated genes involved in the neuropathology are largely ill-defined. Recent epidemiological and biochemical evidence suggests that methylmercury (MeHg) may be an environmental toxicant that contributes to the development of PD. Here, we report that a gene coding for the putative multidrug resistance protein MRP-7 in Caenorhabditis elegans modulates whole animal and DA neuron sensitivity to MeHg. In this study, we demonstrate that genetic knockdown of MRP-7 results in a twofold increase in Hg levels and a dramatic increase in stress response proteins associated with the endoplasmic reticulum, golgi apparatus, and mitochondria, as well as an increase in MeHg-associated animal death. Chronic exposure to low concentrations of MeHg induces MRP-7 gene expression, while exposures in MRP-7 genetic knockdown animals results in a loss of DA neuron integrity without affecting whole animal viability. Furthermore, transgenic animals expressing a fluorescent reporter behind the endogenous MRP-7 promoter indicate that the transporter is expressed in DA neurons. These studies show for the first time that a multidrug resistance protein is expressed in DA neurons, and its expression inhibits MeHg-associated DA neuron pathology.
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Affiliation(s)
- Natalia VanDuyn
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, Indiana, USA
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26
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ATP binding to two sites is necessary for dimerization of nucleotide-binding domains of ABC proteins. Biochem Biophys Res Commun 2013; 443:97-102. [PMID: 24269240 DOI: 10.1016/j.bbrc.2013.11.050] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2013] [Accepted: 11/12/2013] [Indexed: 01/05/2023]
Abstract
ATP binding cassette (ABC) transporters have a functional unit formed by two transmembrane domains and two nucleotide binding domains (NBDs). ATP-bound NBDs dimerize in a head-to-tail arrangement, with two nucleotides sandwiched at the dimer interface. Both NBDs contribute residues to each of the two nucleotide-binding sites (NBSs) in the dimer. In previous studies, we showed that the prototypical NBD MJ0796 from Methanocaldococcus jannaschii forms ATP-bound dimers that dissociate completely following hydrolysis of one of the two bound ATP molecules. Since hydrolysis of ATP at one NBS is sufficient to drive dimer dissociation, it is unclear why all ABC proteins contain two NBSs. Here, we used luminescence resonance energy transfer (LRET) to study ATP-induced formation of NBD homodimers containing two NBSs competent for ATP binding, and NBD heterodimers with one active NBS and one binding-defective NBS. The results showed that binding of two ATP molecules is necessary for NBD dimerization. We conclude that ATP hydrolysis at one nucleotide-binding site drives NBD dissociation, but two binding sites are required to form the ATP-sandwich NBD dimer necessary for hydrolysis.
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Simon F, Varela D, Cabello-Verrugio C. Oxidative stress-modulated TRPM ion channels in cell dysfunction and pathological conditions in humans. Cell Signal 2013; 25:1614-24. [PMID: 23602937 DOI: 10.1016/j.cellsig.2013.03.023] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2012] [Revised: 03/25/2013] [Accepted: 03/28/2013] [Indexed: 10/27/2022]
Abstract
The transient receptor potential melastatin (TRPM) protein family is an extensive group of ion channels expressed in several types of mammalian cells. Many studies have shown that these channels are crucial for performing several physiological functions. Additionally, a large body of evidence indicates that these channels are also involved in numerous human diseases, known as channelopathies. A characteristic event frequently observed during pathological states is the raising in intracellular oxidative agents over reducing molecules, shifting the redox balance and inducing oxidative stress. In particular, three members of the TRPM subfamily, TRPM2, TRPM4 and TRPM7, share the remarkable feature that their activities are modulated by oxidative stress. Because of the increase in oxidative stress, these TRPM channels function aberrantly, promoting the onset and development of diseases. Increases, absences, or modifications in the function of these redox-modulated TRPM channels are associated with cell dysfunction and human pathologies. Therefore, the effect of oxidative stress on ion channels becomes an essential part of the pathogenic mechanism. Thus, oxidative stress-modulated ion channels are more susceptible to generating pathological states than oxidant-independent channels. This review examines the most relevant findings regarding the participation of the oxidative stress-modulated TRPM ion channels, TRPM2, TRPM4, and TRPM7, in human diseases. In addition, the potential roles of these channels as therapeutic tools and targets for drug design are discussed.
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Affiliation(s)
- Felipe Simon
- Departamento de Ciencias Biológicas, Facultad de Ciencias Biológicas and Facultad de Medicina, Universidad Andres Bello, Avenida Republica 239, 8370146, Santiago, Chile.
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28
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Gromiha MM, Ou YY. Bioinformatics approaches for functional annotation of membrane proteins. Brief Bioinform 2013; 15:155-68. [DOI: 10.1093/bib/bbt015] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Zhang C, Kwan P, Zuo Z, Baum L. The transport of antiepileptic drugs by P-glycoprotein. Adv Drug Deliv Rev 2012; 64:930-42. [PMID: 22197850 DOI: 10.1016/j.addr.2011.12.003] [Citation(s) in RCA: 120] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2011] [Revised: 12/05/2011] [Accepted: 12/07/2011] [Indexed: 01/16/2023]
Abstract
Epilepsy is the most common serious chronic neurological disorder. Current data show that one-third of patients do not respond to anti-epileptic drugs (AEDs). Most non-responsive epilepsy patients are resistant to several, often all, AEDs, even though the drugs differ from each other in pharmacokinetics, mechanisms of action, and interaction potential. The mechanisms underlying drug resistance of epilepsy patients are still not clear. In recent years, one of the potential mechanisms interesting researchers is over-expression of P-glycoprotein (P-gp, also known as ABCB1 or MDR1) in endothelial cells of the blood-brain barrier (BBB) in epilepsy patients. P-gp plays a central role in drug absorption and distribution in many organisms. The expression of P-gp is greater in drug-resistant than in drug-responsive patients. Some studies also indicate that several AEDs are substrates or inhibitors of P-gp, implying that P-gp may play an important role in drug resistance in refractory epilepsy. In this article, we review the clinical and laboratory evidence that P-gp expression is increased in epileptic brain tissues and that AEDs are substrates of P-gp in vitro and in vivo. We discuss criteria for identifying the substrate status of AEDs and use structure-activity relationship (SAR) models to predict which AEDs act as P-gp substrates.
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Ivacaftor potentiation of multiple CFTR channels with gating mutations. J Cyst Fibros 2012; 11:237-45. [DOI: 10.1016/j.jcf.2011.12.005] [Citation(s) in RCA: 312] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2011] [Revised: 12/21/2011] [Accepted: 12/27/2011] [Indexed: 01/09/2023]
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De la Rosa MB, Nelson SW. An interaction between the Walker A and D-loop motifs is critical to ATP hydrolysis and cooperativity in bacteriophage T4 Rad50. J Biol Chem 2011; 286:26258-66. [PMID: 21610075 PMCID: PMC3138309 DOI: 10.1074/jbc.m111.256305] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2011] [Revised: 05/20/2011] [Indexed: 11/06/2022] Open
Abstract
The ATP binding cassette (ABC) proteins make up a large superfamily with members coming from all kingdoms. The functional form of the ABC protein nucleotide binding domain (NBD) is dimeric with ATP binding sites shared between subunits. The NBD is defined by six motifs: the Walker A, Q-loop, Signature, Walker-B, D-loop, and H-loop. The D-loop contains a conserved aspartate whose function is not clear but has been proposed to be involved in cross-talk between ATP binding sites. Structures of various ABC proteins suggest an interaction between the D-loop aspartate and an asparagine residue located in Walker A loop of the opposing subunit. Here, we evaluate the functional role of the D-loop using a bacteriophage T4 ABC protein, Rad50 (gp46). Mutation of either the D-loop aspartate or the Walker A asparagine results in dramatic reductions in ATP affinity, hydrolysis rate, and cooperativity. The mutant proteins bind Mre11 (gp47) and DNA normally, but no longer support the ATP-dependent nuclease activities of Mre11. We propose that the D-loop aspartate functions to stabilize the Walker A asparagine in a position favorable for catalysis. We find that the asparagine is crucially important to the mechanism of ATP hydrolysis by increasing the affinity for ATP and positioning the γ-phosphate of ATP for catalysis. Additionally, we propose that the asparagine acts as a γ-phosphate sensor and, through its interaction with the conserved D-loop aspartate, transmits conformational changes across the dimer interface to the second ATP binding site.
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Affiliation(s)
- Metzere Bierlein De la Rosa
- From the Program for Women in Science and Engineering and
- the Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, Ames, Iowa 50011 and
- Grinnell College, Grinnell, Iowa 50112
| | - Scott W. Nelson
- the Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, Ames, Iowa 50011 and
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Froklage FEAM, Reijneveld JC, Heimans JJ. Central neurotoxicity in cancer chemotherapy: pharmacogenetic insights. Pharmacogenomics 2011; 12:379-95. [PMID: 21449677 DOI: 10.2217/pgs.10.197] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Central neurotoxicity of chemotherapy is likely to be multifactorial. There are two hypotheses regarding endogenous mechanisms that may be involved, namely the target and the blood-brain barrier transporter hypotheses. Here, we will review candidate genetic determinants for the risk of chemotherapy-induced neurotoxicity, such as polymorphisms involved in the target mechanism. These include polymorphisms in folate metabolizing enzymes and apolipoprotein E, as well as those in blood-brain barrier transporter genes. Currently, the exact role of pharmacogenetics in mechanisms that lead to central neurotoxicity of chemotherapy has not been fully unraveled. Larger, prospective, longitudinal and more uniform studies are needed, with prechemotherapy and follow-up measurements of neuropsychological performance, MRI, PET, genetic profiles and biomarkers relevant for the proposed target and transporter mechanisms.
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Affiliation(s)
- Femke E A M Froklage
- VU University Medical Center, Department of Neurology, Amsterdam, The Netherlands.
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Gulshan K, Moye-Rowley WS. Vacuolar import of phosphatidylcholine requires the ATP-binding cassette transporter Ybt1. Traffic 2011; 12:1257-68. [PMID: 21649806 DOI: 10.1111/j.1600-0854.2011.01228.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
ATP-binding cassette (ABC) transporters are well known for their roles as multidrug resistance determinants but also play important roles in regulation of lipid levels. In the yeast Saccharomyces cerevisiae, the plasma membrane ABC transporter proteins Pdr5 and Yor1 are required for normal rates of transport of phosphatidyethanolamine to the surface of the cell. Loss of these ABC transporters causes a defect in phospholipid asymmetry across the plasma membrane and has been linked with slowed rates of trafficking of other membrane proteins. Four ABC transporter proteins are found on the limiting membrane of the yeast vacuole and loss of one of these vacuolar ABC transporters, Ybt1, caused a major defect in the normal delivery of the phosphatidylcholine (PC) analog NBD-PC (7-nitro-2,1,3-benzoxadiazol-PC) to the lumen of the vacuole. NBD-PC accumulates on cytosolic membranes in an ybt1Δ strain. We demonstrated that Ybt1 is required to import NBD-PC into vacuoles in the presence of ATP in vitro. Loss of Ybt1 prevented vacuolar remodeling of PC analogs. Turnover of Ybt1 was reduced under conditions in which function of this vacuolar remodeling pathway was required. Our data describe a novel vacuolar route for lipid remodeling and reutilization in addition to previously described enzymatic avenues in the cytoplasm.
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Affiliation(s)
- Kailash Gulshan
- Department of Molecular Physiology and Biophysics, Carver College of Medicine, 6-530 Bowen Science Building, University of Iowa, Iowa City, IA 52246, USA
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Guinamard R, Sallé L, Simard C. The non-selective monovalent cationic channels TRPM4 and TRPM5. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2011; 704:147-71. [PMID: 21290294 DOI: 10.1007/978-94-007-0265-3_8] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Transient Receptor Potential (TRP) proteins are non-selective cationic channels with a consistent Ca(2+)-permeability, except for TRPM4 and TRPM5 that are not permeable to this ion. However, Ca(2+) is a major regulator of their activity since both channels are activated by a rise in internal Ca(2+). Thus TRPM4 and TRPM5 are responsible for most of the Ca(2+)-activated non-selective cationic currents (NSC(Ca)) recorded in a large variety of tissues. Their activation induces cell-membrane depolarization that modifies the driving force for ions as well as activity of voltage gated channels and thereby strongly impacts cell physiology. In the last few years, the ubiquitously expressed TRPM4 channel has been implicated in insulin secretion, the immune response, constriction of cerebral arteries, the activity of inspiratory neurons and cardiac dysfunction. Conversely, TRPM5 whose expression is more restricted, has until now been mainly implicated in taste transduction.
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Affiliation(s)
- Romain Guinamard
- Groupe Cœur et Ischémie, EA 3212, Université de Caen, Sciences D, F-14032, Caen Cedex, France,
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35
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Long Y, Li Q, Li J, Cui Z. Molecular analysis, developmental function and heavy metal-induced expression of ABCC5 in zebrafish. Comp Biochem Physiol B Biochem Mol Biol 2011; 158:46-55. [DOI: 10.1016/j.cbpb.2010.09.005] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2010] [Revised: 09/14/2010] [Accepted: 09/14/2010] [Indexed: 01/07/2023]
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36
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Amann T, Schell S, Kühner P, Winkler M, Schwanstecher M, Russ U, Quast U. Substitution of the Walker A lysine by arginine in the nucleotide-binding domains of sulphonylurea receptor SUR2B: effects on ligand binding and channel activity. Naunyn Schmiedebergs Arch Pharmacol 2010; 381:507-16. [PMID: 20352196 DOI: 10.1007/s00210-010-0510-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2009] [Accepted: 02/28/2010] [Indexed: 10/19/2022]
Abstract
Sulphonylurea receptors (SURs) serve as regulatory subunits of ATP-sensitive K(+) channels. SURs are members of the ATP-binding cassette (ABC) protein superfamily and contain two conserved nucleotide-binding domains (NBDs) which bind and hydrolyse MgATP; in addition, they carry the binding sites for the sulphonylureas like glibenclamide (GBC) which close the channel and for the K(ATP) channel openers such as P1075. Here we have exchanged the conserved Lys in the Walker A motif by Arg in both NBDs of SUR2B, the regulatory subunit of the vascular K(ATP) channel. Then the effect of the mutation on the ATPase-dependent binding of GBC and P1075 to SUR2B and on the activity of the recombinant vascular (Kir6.1/SUR2B) channel was assessed. Surprisingly, in the absence of MgATP, the mutation weakened binding of P1075 and the extent of allosteric inhibition of GBC binding by P1075. The mutation abolished most, but not all, of the MgATP effects on the binding of GBC and P1075 and prevented nucleotide-induced activation of the channel which relies on SUR reaching the posthydrolytic (MgADP-bound) state; the mutant channel was, however, opened by P1075 at higher concentrations. The data provide evidence that mutant SUR2B binds MgATP but that the posthydrolytic state is insufficiently populated. This suggests that the mutation locks SUR2B in an MgATP-binding prehydrolytic-like state; binding of P1075 may induce a posthydrolytic-like conformation to open the channel.
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Affiliation(s)
- Tobias Amann
- Department of Pharmacology and Experimental Therapy, Institute of Experimental and Clinical Pharmacology and Toxicology, Eberhard-Karls-University Hospitals and Clinics, University of Tübingen, Wilhelmstr. 56, 72074, Tübingen, Germany
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37
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Zhou J, He WY, Wang WN, Yang CW, Wang L, Xin Y, Wu J, Cai DX, Liu Y, Wang AL. Molecular cloning and characterization of an ATP-binding cassette (ABC) transmembrane transporter from the white shrimp Litopenaeusvannamei. Comp Biochem Physiol C Toxicol Pharmacol 2009; 150:450-8. [PMID: 19595789 DOI: 10.1016/j.cbpc.2009.06.012] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/05/2009] [Revised: 06/26/2009] [Accepted: 06/30/2009] [Indexed: 01/18/2023]
Abstract
ATP-binding cassette transmembrane transporters (ABC transporters) have a potential role in drug and xenobiotic resistance. Here, we report for the first time the cloning of an ABC transporter from white shrimp Litopenaeusvannamei (designated LvABCG), along with a study of its phylogenetic relationships, and measurements of its expression in different shrimp tissues exposed to cadmium and pH stress (acidic and alkaline conditions). Sequence analysis showed that LvABCG shares many similarities with the white/ABC transmembrane transporter, including two conserved regions: a highly conserved ATP-binding cassette (ABC) and transmembrane domain (TMD). Spatial analyses of transcript levels for ABCG in shrimp tissues, using reverse transcript PCR, revealed the highest transcript level in the hepatopancreas, less in the intestine and stomach, and none in the other tissues examined. The ABC transporter mRNA transcript in the hepatopancreas of L.vannamei was significantly up-regulated after 1.5 h and 24 h of exposure to alkaline and acidic conditions, respectively. LvABCG was also induced in intestine, but was downregulated in the stomach under the alkaline treatment. Upon exposure to cadmium (4.25 micromol L(-1) and 8.5 micromol L(-1)) for 48 h, the mRNA expression of LvABCG was up-regulated 4.79-fold (at 6 h) and 2.09-fold (at 12 h) in the hepatopancreas. LvABCG was also induced in the stomach after exposure to 4.25 micromol L(-1) cadmium, but downregulated in the stomach and intestine after exposure to 8.5 micromol L(-1) cadmium. These findings indicate that LvABCG might play an important role in the physiological changes related to metabolism and cell detoxification that occur when Pacific white shrimp are exposed to cadmium and pH stress.
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MESH Headings
- ATP-Binding Cassette Transporters/chemistry
- ATP-Binding Cassette Transporters/genetics
- ATP-Binding Cassette Transporters/metabolism
- Amino Acid Motifs
- Amino Acid Sequence
- Animals
- Base Sequence
- Cadmium/toxicity
- Cloning, Molecular
- Conserved Sequence
- DNA, Complementary/biosynthesis
- DNA, Complementary/chemistry
- DNA, Complementary/genetics
- Dose-Response Relationship, Drug
- Gastric Mucosa/metabolism
- Gene Expression Regulation
- Hepatopancreas/metabolism
- Hydrogen-Ion Concentration
- Intestinal Mucosa/metabolism
- Molecular Sequence Data
- Penaeidae/genetics
- Penaeidae/metabolism
- Phylogeny
- Protein Structure, Secondary
- Protein Structure, Tertiary
- RNA, Messenger/metabolism
- Sequence Analysis, DNA
- Sequence Homology, Amino Acid
- Stress, Physiological
- Time Factors
- Tissue Distribution
- Toxicity Tests, Acute
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Affiliation(s)
- Jun Zhou
- Key Laboratory of Ecology and Environmental Science in Guangdong Higher Education, College of Life Science, South China Normal University, Guangzhou 510631, PR China
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38
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Eckford PDW, Sharom FJ. ABC efflux pump-based resistance to chemotherapy drugs. Chem Rev 2009; 109:2989-3011. [PMID: 19583429 DOI: 10.1021/cr9000226] [Citation(s) in RCA: 455] [Impact Index Per Article: 30.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Paul D W Eckford
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada N1G 2W1
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Nagy R, Grob H, Weder B, Green P, Klein M, Frelet-Barrand A, Schjoerring JK, Brearley C, Martinoia E. The Arabidopsis ATP-binding cassette protein AtMRP5/AtABCC5 is a high affinity inositol hexakisphosphate transporter involved in guard cell signaling and phytate storage. J Biol Chem 2009; 284:33614-22. [PMID: 19797057 DOI: 10.1074/jbc.m109.030247] [Citation(s) in RCA: 155] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Arabidopsis possesses a superfamily of ATP-binding cassette (ABC) transporters. Among these, the multidrug resistance-associated protein AtMRP5/AtABCC5 regulates stomatal aperture and controls plasma membrane anion channels of guard cells. Remarkably, despite the prominent role of AtMRP5 in conferring partial drought insensitivity upon Arabidopsis, we know little of the biochemical function of AtMRP5. Our phylogenetic analysis showed that AtMRP5 is closely related to maize MRP4, mutation of which confers a low inositol hexakisphosphate kernel phenotype. We now show that insertion mutants of AtMRP5 display a low inositol hexakisphosphate phenotype in seed tissue and that this phenotype is associated with alterations of mineral cation and phosphate status. By heterologous expression in yeast, we demonstrate that AtMRP5 encodes a specific and high affinity ATP-dependent inositol hexakisphosphate transporter that is sensitive to inhibitors of ABC transporters. Moreover, complementation of the mrp5-1 insertion mutants of Arabidopsis with the AtMRP5 cDNA driven from a guard cell-specific promoter restores the sensitivity of the mutant to abscisic acid-mediated inhibition of stomatal opening. Additionally, we show that mutation of residues of the Walker B motif prevents restoring the multiple phenotypes associated with mrp5-1. Our findings highlight a novel function of plant ABC transporters that may be relevant to other kingdoms. They also extend the signaling repertoire of this ubiquitous inositol polyphosphate signaling molecule.
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Affiliation(s)
- Réka Nagy
- University of Zurich, Institute of Plant Biology, Zollikerstrasse 107, CH-8008 Zürich, Switzerland.
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40
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Cadmium and mitochondria. Mitochondrion 2009; 9:377-84. [PMID: 19706341 DOI: 10.1016/j.mito.2009.08.009] [Citation(s) in RCA: 140] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2009] [Revised: 08/18/2009] [Accepted: 08/19/2009] [Indexed: 11/20/2022]
Abstract
The heavy metal cadmium (Cd) a pollutant associated with several modern industrial processes, is absorbed in significant quantities from cigarette smoke, water, food and air contaminations. It is known to have numerous undesirable effects on health in both experimental animals and humans, targeting kidney, liver and vascular system. The molecular mechanism accounting for most of the biological effects of Cd are not well-understood and the toxicity targets are largely unidentified. The present review focuses on important recent advances about the effects of cadmium on mitochondria of mammalian cells. Mitochondria are the proverbial powerhouses of the cell, running the fundamental biochemical processes that produce energy from nutrients using oxygen. They are among the key intracellular targets for different stressors including Cd. This review provides new additional informations on the cellular and molecular aspects of the interaction between Cd and cells, emphasizing alterations of mitochondria as important events in Cd cytotoxicity, thus representing an important basis for understanding the mechanisms of cadmium effect on the cells.
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Meiotic localization of Mre11 and Rad50 in wild type, spo11-1, and MRN complex mutants of Coprinus cinereus. Chromosoma 2009; 118:471-86. [PMID: 19396455 DOI: 10.1007/s00412-009-0209-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2009] [Revised: 02/28/2009] [Accepted: 03/07/2009] [Indexed: 10/20/2022]
Abstract
The Mre11-Rad50-Nbs1 (MRN) complex is required for numerous cellular processes that involve interactions with DNA double-strand breaks. For the majority of these processes, the MRN complex is thought to act as a unit, with each protein aiding the activity of the others. We have examined the relationship between Mre11 and Rad50 during meiosis in the basidiomycete Coprinus cinereus (Coprinopsis cinerea), investigating to what extent activities of Mre11 and Rad50 are interdependent. We showed that mre11-1 is epistatic to rad50-1 with respect to the time of meiotic arrest, indicating that Mre11 activity facilitates the diffuse diplotene arrest of rad50 mutants. Anti-Mre11 and anti-Rad50 antibodies were used to examine MRN complex localization in a wild-type strain and in spo11, mre11, and rad50 mutants. In wild type, numbers of Mre11 and Rad50 foci peaked at time points corresponding to leptotene and early zygotene. In the spo11-1 mutant, which is defective in meiotic double-strand break formation, foci accumulated throughout prophase I. Of seven MRN mutants examined, only two rad50 strains exhibited Mre11 and Rad50 foci that localized to chromatin, although Mre11 protein was found in the cell for all of them. Analysis of predicted mutant structures showed that stable localization of Mre11 and Rad50 does not depend upon a wild-type hook-proximal coiled coil, but does require the presence of the Rad50 ATPase/adenylate cyclase domains. We found that Mre11 and Rad50 were interdependent for binding to meiotic chromosomes. However, the majority of foci observed apparently contained only one of the two proteins. Independent Mre11 and Rad50 foci might indicate disassociation of the complex during meiosis or could reflect independent structural roles for the two proteins in meiotic chromatin.
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Intracellular localization of the ABCC proteins of Leishmania and their role in resistance to antimonials. Antimicrob Agents Chemother 2009; 53:2646-9. [PMID: 19307364 DOI: 10.1128/aac.01474-08] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The ABCC subfamily of proteins is composed of nine members in Leishmania. We report that all of these proteins have an intracellular localization and that the overexpression of at least four members, ABCC3, ABCC4, ABCC5, and ABCC7, can confer resistance to antimonials, the first-line drug against Leishmania.
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Torres C, Galián C, Freiberg C, Fantino JR, Jault JM. The YheI/YheH heterodimer from Bacillus subtilis is a multidrug ABC transporter. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2009; 1788:615-22. [DOI: 10.1016/j.bbamem.2008.12.012] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2008] [Revised: 12/12/2008] [Accepted: 12/22/2008] [Indexed: 12/12/2022]
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Byrne JA, Strautnieks SS, Ihrke G, Pagani F, Knisely AS, Linton KJ, Mieli-Vergani G, Thompson RJ. Missense mutations and single nucleotide polymorphisms in ABCB11 impair bile salt export pump processing and function or disrupt pre-messenger RNA splicing. Hepatology 2009; 49:553-67. [PMID: 19101985 DOI: 10.1002/hep.22683] [Citation(s) in RCA: 126] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
UNLABELLED The gene encoding the human bile salt export pump (BSEP), ABCB11, is mutated in several forms of intrahepatic cholestasis. Here we classified the majority (63) of known ABCB11 missense mutations and 21 single-nucleotide polymorphisms (SNPs) to determine whether they caused abnormal ABCB11 pre-messenger RNA splicing, abnormal processing of BSEP protein, or alterations in BSEP protein function. Using an in vitro minigene system to analyze splicing events, we found reduced wild-type splicing for 20 mutations/SNPs, with normal mRNA levels reduced to 5% or less in eight cases. The common ABCB11 missense mutation encoding D482G enhanced aberrant splicing, whereas the common SNP A1028A promoted exon skipping. Addition of exogenous splicing factors modulated several splicing defects. Of the mutants expressed in vitro in CHO-K1 cells, most appeared to be retained in the endoplasmic reticulum and degraded. A minority had BSEP levels similar to wild-type. The SNP variant A444 had reduced levels of protein compared with V444. Treatment with glycerol and incubation at reduced temperature overcame processing defects for several mutants, including E297G. Taurocholate transport by two assessed mutants, N490D and A570T, was reduced compared with wild-type. CONCLUSION This work is a comprehensive analysis of 80% of ABCB11 missense mutations and single-nucleotide polymorphisms at pre-mRNA splicing and protein processing/functional levels. We show that aberrant pre-mRNA splicing occurs in a considerable number of cases, leading to reduced levels of normal mRNA. Thus, primary defects at either the protein or the mRNA level (or both) contribute significantly to BSEP deficiency. These results will help to develop mutation-specific therapies for children and adults suffering from intrahepatic cholestasis due to BSEP deficiency.
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Affiliation(s)
- Jane A Byrne
- Division of Gene and Cell Based Therapy, King's College London School of Medicine, London, UK.
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45
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Dietrich D, Schmuths H, De Marcos Lousa C, Baldwin JM, Baldwin SA, Baker A, Theodoulou FL, Holdsworth MJ. Mutations in the Arabidopsis peroxisomal ABC transporter COMATOSE allow differentiation between multiple functions in planta: insights from an allelic series. Mol Biol Cell 2008; 20:530-43. [PMID: 19019987 DOI: 10.1091/mbc.e08-07-0745] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
COMATOSE (CTS), the Arabidopsis homologue of human Adrenoleukodystrophy protein (ALDP), is required for import of substrates for peroxisomal beta-oxidation. A new allelic series and a homology model based on the bacterial ABC transporter, Sav1866, provide novel insights into structure-function relations of ABC subfamily D proteins. In contrast to ALDP, where the majority of mutations result in protein absence from the peroxisomal membrane, all CTS mutants produced stable protein. Mutation of conserved residues in the Walker A and B motifs in CTS nucleotide-binding domain (NBD) 1 resulted in a null phenotype but had little effect in NBD2, indicating that the NBDs are functionally distinct in vivo. Two alleles containing mutations in NBD1 outside the Walker motifs (E617K and C631Y) exhibited resistance to auxin precursors 2,4-dichlorophenoxybutyric acid (2,4-DB) and indole butyric acid (IBA) but were wild type in all other tests. The homology model predicted that the transmission interfaces are domain-swapped in CTS, and the differential effects of mutations in the conserved "EAA motif" of coupling helix 2 supported this prediction, consistent with distinct roles for each NBD. Our findings demonstrate that CTS functions can be separated by mutagenesis and the structural model provides a framework for interpretation of phenotypic data.
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Affiliation(s)
- Daniela Dietrich
- Department of Plant and Crop Sciences, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, United Kingdom
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46
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Janke D, Mehralivand S, Strand D, Gödtel-Armbrust U, Habermeier A, Gradhand U, Fischer C, Toliat MR, Fritz P, Zanger UM, Schwab M, Fromm MF, Nürnberg P, Wojnowski L, Closs EI, Lang T. 6-mercaptopurine and 9-(2-phosphonyl-methoxyethyl) adenine (PMEA) transport altered by two missense mutations in the drug transporter gene ABCC4. Hum Mutat 2008; 29:659-69. [PMID: 18300232 DOI: 10.1002/humu.20694] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Multiple drug resistance protein 4 (MRP4, ABCC4) belongs to the C subfamily of the ATP-binding cassette (ABC) transporter superfamily and participates in the transport of diverse antiviral and chemotherapeutic agents such as 6-mercaptopurine (6-MP) and 9-(2-phosphonyl methoxyethyl) adenine (PMEA). We have undertaken a comprehensive functional characterization of protein variants of MRP4 found in Caucasians and other ethnicities. A total of 11 MRP4 missense genetic variants (nonsynonymous SNPs), fused to green fluorescent protein (GFP), were examined in Xenopus laevis oocytes for their effect on expression, localization, and function of the transporter. Radiolabeled 6-MP and PMEA were chosen as transport substrates. All MRP4 protein variants were found to be expressed predominantly in the oocyte membrane. A total of four variants (Y556C, E757 K, V776I, and T1142 M) exhibited a 20% to 40% reduced expression level compared to the wild type. Efflux studies showed that 6-MP is transported by MRP4 in unmodified form. Compared to wild-type MRP4, the transmembrane variant V776I, revealed a significant lower activity in 6-MP transport, while the amino acid exchange Y556C in the Walker(B) motif displayed significantly higher transport of PMEA. The transport properties of the other variants were comparable to wild-type MRP4. Our study shows that Xenopus oocytes are well suited to characterize MRP4 and its protein variants. Carriers of the rare MRP4 variants Y556C and V776I may have altered disposition of MRP4 substrates.
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Affiliation(s)
- Daniel Janke
- Institute of Pharmacology, University of Mainz, Mainz, Germany
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47
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Landfear SM. Drugs and transporters in kinetoplastid protozoa. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2008; 625:22-32. [PMID: 18365656 DOI: 10.1007/978-0-387-77570-8_3] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Kinetoplastid protozoa express hundreds of membrane transport proteins that allow them to take up nutrients, establish ion gradients, efflux metabolites, translocate compounds from one intracellular compartment to another, and take up or export drugs. The combination of molecular cloning, genetic approaches, and the completed genome projects for Trypanosoma brucei, Leishmania major, and Trypanosoma cruzi have allowed detailed functional analysis of various transporters and predictions about the likely functions of others. Thus many opportunities exist to define the biological and pharmacological properties of parasite transporters whose genes were often difficult to identify in the pregenomic era. A subset of these transporters that are essential for parasite viability could serve as targets for novel drug therapies by identifying compounds that interfere with their uptake functions. Other permeases provide routes for uptake of selectively cytotoxic compounds and can thus be useful for delivery of drugs. Drug resistance may develop in strains where such drug uptake transporters are nonfunctional or in parasites that over-express other permeases that export a drug. A summary of recent work on Leishmania transporters for glucose and for purines is provided as an example of permeases that are being studied in molecular detail.
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Affiliation(s)
- Scott M Landfear
- Department of Molecular Microbiology and Immunology, Oregon Health & Science University, Portland, Oregon 97239, USA.
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48
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Frelet-Barrand A, Kolukisaoglu HU, Plaza S, Rüffer M, Azevedo L, Hörtensteiner S, Marinova K, Weder B, Schulz B, Klein M. Comparative mutant analysis of Arabidopsis ABCC-type ABC transporters: AtMRP2 contributes to detoxification, vacuolar organic anion transport and chlorophyll degradation. PLANT & CELL PHYSIOLOGY 2008; 49:557-69. [PMID: 18325934 DOI: 10.1093/pcp/pcn034] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
The enormous metabolic plasticity of plants allows detoxification of many harmful compounds that are generated during biosynthetic processes or are present as biotic or abiotic toxins in their environment. Derivatives of toxic compounds such as glutathione conjugates are moved into the central vacuole via ATP-binding cassette (ABC)-type transporters of the multidrug resistance-associated protein (MRP) subfamily. The Arabidopsis genome contains 15 AtMRP isogenes, four of which (AtMRP1, 2, 11 and 12) cluster together in one of two major phylogenetic clades. We isolated T-DNA knockout alleles in all four highly homologous AtMRP genes of this clade and subjected them to physiological analysis to assess the function of each AtMRP of this group. None of the single atmrp mutants displayed visible phenotypes under control conditions. In spite of the fact that AtMRP1 and AtMRP2 had been described as efficient ATP-dependent organic anion transporters in heterologous expression experiments, the contribution of three of the AtMRP genes (1, 11 and 12) to detoxification is marginal. Only knockouts in AtMRP2 exhibited a reduced sensitivity towards 1-chloro-2,4-dinitrobenzene, but not towards other herbicides. AtMRP2 but not AtMRP1, 11 and 12 is involved in chlorophyll degradation since ethylene-treated rosettes of atmrp2 showed reduced senescence, and AtMRP2 expression is induced during senescence. This suggests that AtMRP2 is involved in vacuolar transport of chlorophyll catabolites. Vacuolar uptake studies demonstrated that transport of typical MRP substrates was reduced in atmrp2. We conclude that within clade I, only AtMRP2 contributes significantly to overall organic anion pump activity in vivo.
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Affiliation(s)
- Annie Frelet-Barrand
- Zurich Basel Plant Science Center, University of Zurich, Plant Biology, Zollikerstrasse 107, CH-8008 Zürich, Switzerland
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49
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Sharom FJ. ABC multidrug transporters: structure, function and role in chemoresistance. Pharmacogenomics 2008; 9:105-27. [PMID: 18154452 DOI: 10.2217/14622416.9.1.105] [Citation(s) in RCA: 692] [Impact Index Per Article: 43.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Three ATP-binding cassette (ABC)-superfamily multidrug efflux pumps are known to be responsible for chemoresistance; P-glycoprotein (ABCB1), MRP1 (ABCC1) and ABCG2 (BCRP). These transporters play an important role in normal physiology by protecting tissues from toxic xenobiotics and endogenous metabolites. Hydrophobic amphipathic compounds, including many clinically used drugs, interact with the substrate-binding pocket of these proteins via flexible hydrophobic and H-bonding interactions. These efflux pumps are expressed in many human tumors, where they likely contribute to resistance to chemotherapy treatment. However, the use of efflux-pump modulators in clinical cancer treatment has proved disappointing. Single nucleotide polymorphisms in ABC drug-efflux pumps may play a role in responses to drug therapy and disease susceptibility. The effect of various genotypes and haplotypes on the expression and function of these proteins is not yet clear, and their true impact remains controversial.
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Affiliation(s)
- Frances J Sharom
- University of Guelph, Department of Molecular & Cellular Biology, Guelph Ontario, N1G 2W1, Canada.
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50
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Abstract
BACKGROUND AND PURPOSE TRPM4 and TRPM5 are calcium-activated non-selective cation channels with almost identical characteristics. TRPM4 is detected in several tissues including heart, kidney, brainstem, cerebral artery and immune system whereas TRPM5 expression is more restricted. Determination of their roles in physiological processes requires specific pharmacological tools. TRPM4 is inhibited by glibenclamide, a modulator of ATP binding cassette proteins (ABC transporters), such as the cystic fibrosis transmembrane conductance regulator (CFTR). We took advantage of this similarity to investigate the effect of hydroxytricyclic compounds shown to modulate ABC transporters, on TRPM4 and TRPM5. EXPERIMENTAL APPROACH Experiments were conducted using HEK-293 cells permanently transfected to express human TRPM4 or TRPM5. Currents were recorded using the whole-cell and inside-out variants of the patch-clamp technique. KEY RESULTS The CFTR channel activator benzo[c]quinolizinium MPB-104 inhibited TRPM4 current with an IC(50) in the range of 2 x 10(-5) M, with no effect on single-channel conductance. In addition, 9-phenanthrol, lacking the chemical groups necessary for CFTR activation, also reversibly inhibited TRPM4 with a similar IC(50). Channel inhibition was voltage independent. The IC(50) determined in the whole-cell and inside-out experiments were similar, suggesting a direct effect of the molecule. However, 9-phenanthrol was ineffective on TRPM5, the most closely related channel within the TRP protein family. CONCLUSIONS AND IMPLICATIONS We identify 9-phenanthrol as a TRPM4 inhibitor, without effects on TRPM5. It could be valuable in investigating the physiological functions of TRPM4, as distinct from those of TRPM5.
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