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Biochimica Et Biophysica Acta Dec 1999The multidrug resistance P-glycoprotein is an ATP-dependent drug pump that extrudes a broad range of hydrophobic compounds out of cells. Its physiological role is likely... (Review)
Review
The multidrug resistance P-glycoprotein is an ATP-dependent drug pump that extrudes a broad range of hydrophobic compounds out of cells. Its physiological role is likely to protect us from exogenous and endogenous toxins. The protein is important because it contributes to the phenomenon of multidrug resistance during AIDS and cancer chemotherapy. We have used cysteine-scanning mutagenesis and thiol-modification techniques to map the topology of the protein, show that both nucleotide-binding domains are essential for activity, examine packing of the transmembrane segments, map the drug-binding site, and show that there is cross-talk between the ATP-binding sites and the transmembrane segments.
Topics: ATP Binding Cassette Transporter, Subfamily B, Member 1; ATP-Binding Cassette Transporters; Binding Sites; Carrier Proteins; Cell Membrane; Cysteine; Disulfides; Drug Resistance, Multiple; Humans; Intracellular Signaling Peptides and Proteins; Mutagenesis, Site-Directed; Protein Conformation; Protein Folding
PubMed: 10581364
DOI: 10.1016/s0005-2736(99)00165-0 -
Blood Jun 2001The expression of P-glycoprotein (P-gp), encoded by the MDR1 gene, is an independent adverse prognostic factor for response and survival in de novo acute myeloid...
The expression of P-glycoprotein (P-gp), encoded by the MDR1 gene, is an independent adverse prognostic factor for response and survival in de novo acute myeloid leukemia (AML). Little is known about MDR1 expression during the development of disease. The present study investigated whether MDR1 gene- related clonal selection occurs in the development from diagnosis to relapsed AML, using a genetic polymorphism of the MDR1 gene at position 2677. Expression and function of P-gp were studied using monoclonal antibodies MRK16 and UIC2 and the Rhodamine 123 retention assay with or without PSC 833. No difference was found in the levels of P-gp function and expression between diagnosis and relapse in purified paired blast samples from 30 patients with AML. Thirteen patients were homozygous for the genetic polymorphism of MDR1 (n = 7 for guanine, n = 6 for thymidine), whereas 17 patients were heterozygous (GT). In the heterozygous patients, no selective loss of one allele was observed at relapse. Homozygosity for the MDR1 gene (GG or TT) was associated with shorter relapse-free intervals (P =.002) and poor survival rates (P =.02), compared with heterozygous patients. No difference was found in P-gp expression or function in patients with AML with either of the allelic variants of the MDR1 gene. It was concluded that P-gp function or expression is not upregulated at relapse/refractory disease and expression of one of the allelic variants is not associated with altered P-gp expression or function in AML, consistent with the fact that MDR1 gene-related clonal selection does not occur when AML evolves to recurrent disease. (Blood. 2001;97:3605-3611)
Topics: ATP Binding Cassette Transporter, Subfamily B, Member 1; Adolescent; Adult; Aged; Alleles; Antibodies, Monoclonal; Child; Child, Preschool; Gene Expression; Genes, MDR; Heterozygote; Homozygote; Humans; Infant; Leukemia, Myeloid, Acute; Middle Aged; Nucleic Acid Hybridization; Polymorphism, Genetic; Prognosis; Recurrence; Survival Rate
PubMed: 11369657
DOI: 10.1182/blood.v97.11.3605 -
Biochemical Pharmacology Mar 2010The ABC transporter P-glycoprotein is a product of the MDR1 gene and its function in human placenta is to extrude xenobiotics from the tissue thus decreasing fetal...
The ABC transporter P-glycoprotein is a product of the MDR1 gene and its function in human placenta is to extrude xenobiotics from the tissue thus decreasing fetal exposure. The goal of this investigation was to examine the effect of three polymorphisms in the MDR1 gene on the expression and activity of placental P-gp. In 199 term placentas examined, the C1236T variant was associated with 11% lower P-gp protein expression than wild-type, while the C3435T and G2677T/A variants each were associated with a 16% reduction (p<0.05). Homozygotes for the C1236T and C3435T variant allele (TT) were associated with 42% and 47% increase in placental P-gp transport activity, respectively (p=0.04 and p=0.02) of the prototypic substrate, [(3)H]-paclitaxel. These findings indicate that the C3435T and G2677T/A SNPs in MDR1 are significantly associated with decreased placental P-gp protein expression, while the C1236T and C3245T homozygous variants are significantly associated with an increase in its efflux activity.
Topics: ATP Binding Cassette Transporter, Subfamily B, Member 1; Alleles; Biological Transport; Female; Gene Expression Regulation; Genotype; Humans; Placenta; Polymorphism, Genetic; Pregnancy
PubMed: 19896927
DOI: 10.1016/j.bcp.2009.10.026 -
PloS One 2013HIV protease inhibitor (PI)-induced inflammatory response in macrophages is a major risk factor for cardiovascular diseases. We have previously reported that berberine...
BACKGROUND
HIV protease inhibitor (PI)-induced inflammatory response in macrophages is a major risk factor for cardiovascular diseases. We have previously reported that berberine (BBR), a traditional herbal medicine, prevents HIV PI-induced inflammatory response through inhibiting endoplasmic reticulum (ER) stress in macrophages. We also found that HIV PIs significantly increased the intracellular concentrations of BBR in macrophages. However, the underlying mechanisms of HIV PI-induced BBR accumulation are unknown. This study examined the role of P-glycoprotein (P-gp) in HIV PI-mediated accumulation of BBR in macrophages.
METHODOLOGY AND PRINCIPAL FINDINGS
Cultured mouse RAW264.7 macrophages, human THP-1-derived macrophages, Wild type MDCK (MDCK/WT) and human P-gp transfected (MDCK/P-gp) cells were used in this study. The intracellular concentration of BBR was determined by HPLC. The activity of P-gp was assessed by measuring digoxin and rhodamine 123 (Rh123) efflux. The interaction between P-gp and BBR or HIV PIs was predicated by Glide docking using Schrodinger program. The results indicate that P-gp contributed to the efflux of BBR in macrophages. HIV PIs significantly increased BBR concentrations in macrophages; however, BBR did not alter cellular HIV PI concentrations. Although HIV PIs did not affect P-gp expression, P-gp transport activities were significantly inhibited in HIV PI-treated macrophages. Furthermore, the molecular docking study suggests that both HIV PIs and BBR fit the binding pocket of P-gp, and HIV PIs may compete with BBR to bind P-gp.
CONCLUSION AND SIGNIFICANCE
HIV PIs increase the concentration of BBR by modulating the transport activity of P-gp in macrophages. Understanding the cellular mechanisms of potential drug-drug interactions is critical prior to applying successful combinational therapy in the clinic.
Topics: ATP Binding Cassette Transporter, Subfamily B, Member 1; Animals; Berberine; Binding, Competitive; Biological Transport; Cell Line; Chromatography, High Pressure Liquid; Digoxin; Dogs; Gene Expression; HIV Protease Inhibitors; Humans; Macrophages; Madin Darby Canine Kidney Cells; Mice; Molecular Docking Simulation; Protein Binding; Rhodamine 123; Ritonavir
PubMed: 23372711
DOI: 10.1371/journal.pone.0054349 -
The Journal of Biological Chemistry Sep 1995Prenylcysteine methyl esters that represent the C-terminal structures of prenylated proteins demonstrate specific substrate-like interactions with P-glycoprotein (Zhang,... (Comparative Study)
Comparative Study
Prenylcysteine methyl esters that represent the C-terminal structures of prenylated proteins demonstrate specific substrate-like interactions with P-glycoprotein (Zhang, L., Sachs, C. W., Fine, R. L., and Casey, P. J. (1994) J. Biol. Chem. 269, 15973-15976). The simplicity of these compounds provides a unique system for probing the structural specificity of P-glycoprotein substrates. We have further assessed the structural elements of prenylcysteines involved in the interaction with P-glycoprotein. Carboxyl group methylation, a modification in many prenylated proteins, plays an essential role of blocking the negative charge at the free carboxylate. Substitution of the methyl ester with a methyl amide or simple amide does not change the ability of the molecule to stimulate P-glycoprotein ATPase activity, but substitution with a glycine is not tolerated unless the carboxyl group of glycine is methylated. The presence of a nitrogen atom, which is found in many P-glycoprotein substrates and modifiers, is also essential for prenylcysteines to interact with P-glycoprotein. The structure at the nitrogen atom can, however, influence the type of interaction. Acetylation of the free amino group of prenylcysteine/results in a significant loss in the ability of prenylcysteines to stimulate P-glycoprotein ATPase activity. Instead, certain acetylated prenylcysteines behave as inhibitors of this activity. In studies using MDR1-transfected human breast cancer cells, the acetylated prenylcysteine analogs inhibit P-glycoprotein-mediated drug transport and enhance the steady-state accumulation of [3H]vinblastine, [3H]colchicine, and [3H]taxol. These inhibitors do not, however, affect drug accumulation in parental cells. These studies provide a novel approach for designing P-glycoprotein inhibitors that could prove effective in reversing the phenotype of multidrug resistance in tumor cells.
Topics: ATP Binding Cassette Transporter, Subfamily B, Member 1; Adenosine Triphosphatases; Animals; Biological Transport; Breast Neoplasms; Cell Line; Cell Membrane; Cysteine; Drug Resistance, Multiple; Female; Humans; Kinetics; Recombinant Proteins; Spodoptera; Structure-Activity Relationship; Transfection; Tumor Cells, Cultured
PubMed: 7559420
DOI: 10.1074/jbc.270.39.22859 -
Trends in Pharmacological Sciences Oct 2009When cancer cells develop resistance to chemotherapeutics, it is frequently conferred by the ATP-dependent efflux pump P-glycoprotein (MDR1, P-gp, ABCB1). P-gp can... (Review)
Review
When cancer cells develop resistance to chemotherapeutics, it is frequently conferred by the ATP-dependent efflux pump P-glycoprotein (MDR1, P-gp, ABCB1). P-gp can efflux a wide range of cancer drugs; its expression confers cross-resistance, termed "multidrug resistance" (MDR), to a wide range of drugs. Strategies to overcome this resistance have been actively sought for more than 30 years, yet clinical solutions do not exist. A less understood aspect of MDR is the hypersensitivity of resistant cancer cells to other drugs, a phenomenon known as "collateral sensitivity" (CS). This review highlights the extent of this effect for the first time, and discusses hypotheses (e.g. generation of reactive oxygen species) to account for the underlying generality of this phenomenon, and proposes exploitation of CS as a strategy to improve response to chemotherapy.
Topics: ATP Binding Cassette Transporter, Subfamily B, Member 1; Animals; Antineoplastic Agents; Cell Line; Cell Line, Tumor; Drug Interactions; Drug Resistance, Multiple; Drug Resistance, Neoplasm; Humans; Neoplasms; Reactive Oxygen Species
PubMed: 19762091
DOI: 10.1016/j.tips.2009.07.003 -
European Journal of Biochemistry Aug 1998P-glycoprotein functions as an active efflux pump for lipophilic compounds and plays an important role in the resistance of human cancers to chemotherapeutic drugs. Drug...
P-glycoprotein functions as an active efflux pump for lipophilic compounds and plays an important role in the resistance of human cancers to chemotherapeutic drugs. Drug transport is powered by ATP hydrolysis at two highly conserved nucleotide-binding domains, which are proposed to be located at the cytosolic face of the protein. The ATPase activity of P-glycoprotein depends on the presence of phospholipids, and various lipids affect both basal ATPase activity and its stimulation or inhibition by drug substrates. The modulating effects of the lipid-phase state and effects on the function of the nucleotide-binding domains of P-glycoprotein have been studied in reconstituted vesicles of the synthetic phospholipids 1-palmitoyl-2-myristoylphosphatidylcholine (PamMyrGroPCho) and dimyristoylphosphatidylcholine (Myr2GroPCho). The kinetic parameters for P-glycoprotein ATPase activity were determined, and a fluorescence-quenching technique was used to measure the Kd for ATP binding. The values of both the Km for ATP hydrolysis and Kd for ATP binding were significantly different above and below the gel/liquid-crystalline phase transition temperature (tm) of PamMyrGroPCho and Myr2GroPCho, whereas they were similar at the same temperatures for P-glycoprotein in detergent solution. A discontinuity at 21-24 degrees C was observed in the Arrhenius plots of P-glycoprotein ATPase activity in a membrane environment, but not in detergent solution. In addition, the activation energies for ATP hydrolysis in the gel and liquid-crystalline phases of the lipid bilayer were significantly different. P-glycoprotein in PamMyrGroPCho bilayers displayed an unusually low activation energy just below the melting transition. These results indicate that both ATP binding and ATP hydrolysis by P-glycoprotein are affected by the phase state of the host lipids in which it is reconstituted. Lipids may modulate the function of the nucleotide-binding domains of P-glycoprotein by interacting with the transmembrane regions of the protein, or the nucleotide-binding domains themselves may interact with the surface of the bilayer.
Topics: ATP Binding Cassette Transporter, Subfamily B, Member 1; Adenosine Triphosphatases; Adenosine Triphosphate; Animals; CHO Cells; Cricetinae; Hydrolysis; Lipid Bilayers; Phospholipids; Proteolipids
PubMed: 9746361
DOI: 10.1046/j.1432-1327.1998.2560170.x -
The International Journal of... Dec 2004P-glycoprotein (P-gp) in the brain capillary endothelial cell limits the entry of many drugs into the brain. Our previous in-vitro study using ATPase as a marker of P-gp...
P-glycoprotein (P-gp) in the brain capillary endothelial cell limits the entry of many drugs into the brain. Our previous in-vitro study using ATPase as a marker of P-gp activity suggested that risperidone might be effectively transported by P-gp. In the present study, we compared the concentrations of risperidone and its major pharmacologically active metabolite 9-hydroxyrisperidone (9-OH-risperidone), in plasma, brain and various other tissues between abcb1ab-/- knockout mice which are functionally devoid of P-gp in their blood-brain barrier vs. FVB wild-type mice. One hour after intraperitoneal injection of 4 microg/g risperidone, the brain concentrations and ratios of brain:plasma concentrations of risperidone (13.1-fold and 12-fold respectively, p<0.05) and 9-OH-risperidone (29.4-fold and 29-fold respectively, p<0.01) were significantly higher in the abcb1ab-/- mice than those in the FVB mice. These results indicate that P-gp in the blood-brain barrier significantly influences the brain concentrations of risperidone and 9-OH-risperidone by limiting their CNS access.
Topics: ATP Binding Cassette Transporter, Subfamily B, Member 1; Animals; Brain; Chromatography, High Pressure Liquid; Injections, Intraperitoneal; Isoxazoles; Male; Mice; Mice, Transgenic; Paliperidone Palmitate; Pyrimidines; Risperidone; Serotonin Antagonists; Tissue Distribution
PubMed: 15683552
DOI: 10.1017/S1461145704004390 -
Microbiological Reviews Dec 1996Multidrug efflux systems display the ability to transport a variety of structurally unrelated drugs from a cell and consequently are capable of conferring resistance to... (Review)
Review
Multidrug efflux systems display the ability to transport a variety of structurally unrelated drugs from a cell and consequently are capable of conferring resistance to a diverse range of chemotherapeutic agents. This review examines multidrug efflux systems which use the proton motive force to drive drug transport. These proteins are likely to operate as multidrug/proton antiporters and have been identified in both prokaryotes and eukaryotes. Such proton-dependent multidrug efflux proteins belong to three distinct families or superfamilies of transport proteins: the major facilitator superfamily (MFS), the small multidrug resistance (SMR) family, and the resistance/ nodulation/cell division (RND) family. The MFS consists of symporters, antiporters, and uniporters with either 12 or 14 transmembrane-spanning segments (TMS), and we show that within the MFS, three separate families include various multidrug/proton antiport proteins. The SMR family consists of proteins with four TMS, and the multidrug efflux proteins within this family are the smallest known secondary transporters. The RND family consists of 12-TMS transport proteins and includes a number of multidrug efflux proteins with particularly broad substrate specificity. In gram-negative bacteria, some multidrug efflux systems require two auxiliary constituents, which might enable drug transport to occur across both membranes of the cell envelope. These auxiliary constituents belong to the membrane fusion protein and the outer membrane factor families, respectively. This review examines in detail each of the characterized proton-linked multidrug efflux systems. The molecular basis of the broad substrate specificity of these transporters is discussed. The surprisingly wide distribution of multidrug efflux systems and their multiplicity in single organisms, with Escherichia coli, for instance, possessing at least nine proton-dependent multidrug efflux systems with overlapping specificities, is examined. We also discuss whether the normal physiological role of the multidrug efflux systems is to protect the cell from toxic compounds or whether they fulfil primary functions unrelated to drug resistance and only efflux multiple drugs fortuitously or opportunistically.
Topics: ATP Binding Cassette Transporter, Subfamily B, Member 1; Amino Acid Sequence; Biological Transport; Drug Resistance, Multiple; Models, Biological; Molecular Sequence Data; Phylogeny; Proton-Motive Force; Substrate Specificity
PubMed: 8987357
DOI: 10.1128/mr.60.4.575-608.1996 -
International Journal For Parasitology.... Apr 2018Haemonchus contortus, one of the most economically important parasites of small ruminants, has become resistant to the anthelmintic ivermectin. Deciphering the role of...
Haemonchus contortus, one of the most economically important parasites of small ruminants, has become resistant to the anthelmintic ivermectin. Deciphering the role of P-glycoproteins in ivermectin resistance is desirable for understanding and overcoming this resistance. In the model nematode, Caenorhabditis elegans, P-glycoprotein-13 is expressed in the amphids, important neuronal structures for ivermectin activity. We have focused on its ortholog in the parasite, Hco-Pgp-13. A 3D model of Hco-Pgp-13, presenting an open inward-facing conformation, has been constructed by homology with the Cel-Pgp-1 crystal structure. In silico docking calculations predicted high affinity binding of ivermectin and actinomycin D to the inner chamber of the protein. Following in vitro expression, we showed that ivermectin and actinomycin D modulated Hco-Pgp-13 ATPase activity with high affinity. Finally, we found in vivo Hco-Pgp-13 localization in epithelial, pharyngeal and neuronal tissues. Taken together, these data suggest a role for Hco-Pgp-13 in ivermectin transport, which could contribute to anthelmintic resistance.
Topics: ATP Binding Cassette Transporter, Subfamily B, Member 1; Adenosine Triphosphatases; Animals; Antiparasitic Agents; Biological Transport; Caenorhabditis elegans; Computer Simulation; Dactinomycin; Drug Resistance; Epithelium; Haemonchus; Ivermectin; Molecular Docking Simulation; Pharynx; Protein Binding; Structural Homology, Protein
PubMed: 29571165
DOI: 10.1016/j.ijpddr.2018.02.001