scholarly journals Homology modelling of human P-glycoprotein

2015 ◽  
Vol 43 (5) ◽  
pp. 952-958 ◽  
Author(s):  
Laura Domicevica ◽  
Philip C. Biggin
Keyword(s):  
Structural Biology ◽  
Conformational Changes ◽  
Homology Modelling ◽  
Md Simulations ◽  
Multi Drug Resistance ◽  
Glycoprotein P ◽  
The Past ◽  
Atp Binding Cassette Transporter ◽  
P Glycoprotein ◽  
Great Progress

P-glycoprotein (P-gp) is an ATP-binding cassette transporter that exports a huge range of compounds out of cells and is thus one of the key proteins in conferring multi-drug resistance in cancer. Understanding how it achieves such a broad specificity and the series of conformational changes that allow export to occur form major, on-going, research objectives around the world. Much of our knowledge to date has been derived from mutagenesis and assay data. However, in recent years, there has also been great progress in structural biology and although the structure of human P-gp has not yet been solved, there are now a handful of related structures on which homology models can be built to aid in the interpretation of the vast amount of experimental data that currently exists. Many models for P-gp have been built with this aim, but the situation is complicated by the apparent flexibility of the system and by the fact that although many potential templates exist, there is large variation in the conformational state in which they have been crystallized. In this review, we summarize how homology modelling has been used in the past, how models are typically selected and finally illustrate how MD simulations can be used as a means to give more confidence about models that have been generated via this approach.

scholarly journals Substrate Transport is Mediated not only by P-glycoprotein but also by Lipid Penetration

2019 ◽  
Author(s):  
Yuqi Yu ◽  
Jinan Wang ◽  
Zhaoqiang Chen ◽  
Guimin Wang ◽  
Zhijian Xu ◽  
...  
Keyword(s):  
Conformational Changes ◽  
Large Scale ◽  
Md Simulations ◽  
Glycoprotein P ◽  
Transport Pathways ◽  
Future Design ◽  
P Glycoprotein ◽  
Complex Biological Process ◽  
Multiple Ligands ◽  
Ligand Transport

ABSTRACTIn association with large-scale conformational changes, the members of the ATP-binding cassette (ABC) transporter superfamily such as P-glycoprotein (P-gp) pump endogenous cytotoxic substances and exogenous drugs out of cells. Here, a series of nonequilibrium-driven molecular dynamics (MD) simulations are sophisticatedly combined to provide a generally effective access to quantitatively investigate such a complex biological process that has been posing a great challenge for experiments and computational simulations. Both common features and unique characteristics of multiple ligands (substrates or inhibitors) that are recognized by P-gps from mouse and human species are quantitatively explored, providing additional insights into experimentally suggested ligand transport pathways and summarizing the important roles of not only different P-gps but also lipids in regulating ligand transport. These findings reveal the molecular mechanism underlying the transport of ligands by P-gps from different species and emphasize the consideration of lipid effects on the future design of effective P-gp inhibitors.

scholarly journals ATP-dependent thermostabilization of human P-glycoprotein (ABCB1) is blocked by modulators

2019 ◽  
Vol 476 (24) ◽  
pp. 3737-3750 ◽  
Author(s):  
Sabrina Lusvarghi ◽  
Suresh V. Ambudkar
Keyword(s):  
Conformational Changes ◽  
Drug Transport ◽  
Atp Hydrolysis ◽  
Atp Binding ◽  
Dependent Manner ◽  
Deficient Mutant ◽  
Concentration Dependent Manner ◽  
Glycoprotein P ◽  
Binding Domains ◽  
P Glycoprotein

P-glycoprotein (P-gp), an ATP-binding cassette transporter associated with multidrug resistance in cancer cells, is capable of effluxing a number of xenobiotics as well as anticancer drugs. The transport of molecules through the transmembrane (TM) region of P-gp involves orchestrated conformational changes between inward-open and inward-closed forms, the details of which are still being worked out. Here, we assessed how the binding of transport substrates or modulators in the TM region and the binding of ATP to the nucleotide-binding domains (NBDs) affect the thermostability of P-gp in a membrane environment. P-gp stability after exposure at high temperatures (37–80°C) was assessed by measuring ATPase activity and loss of monomeric P-gp. Our results show that P-gp is significantly thermostabilized (>22°C higher IT50) by the binding of ATP under non-hydrolyzing conditions (in the absence of Mg2+). By using an ATP-binding-deficient mutant (Y401A) and a hydrolysis-deficient mutant (E556Q/E1201Q), we show that thermostabilization of P-gp requires binding of ATP to both NBDs and their dimerization. Additionally, we found that transport substrates do not affect the thermal stability of P-gp either in the absence or presence of ATP; in contrast, inhibitors of P-gp including tariquidar and zosuquidar prevent ATP-dependent thermostabilization in a concentration-dependent manner, by stabilizing the inward-open conformation. Altogether, our data suggest that modulators, which bind in the TM regions, inhibit ATP hydrolysis and drug transport by preventing the ATP-dependent dimerization of the NBDs of P-gp.

scholarly journals Transport of Alzheimer’s associated amyloid-β catalyzed by P-glycoprotein

PLoS ONE ◽  
2021 ◽  
Vol 16 (4) ◽  
pp. e0250371
Author(s):  
James W. McCormick ◽  
Lauren Ammerman ◽  
Gang Chen ◽  
Pia D. Vogel ◽  
John G. Wise
Keyword(s):  
Cell Culture ◽  
Atp Hydrolysis ◽  
Amyloid Β ◽  
Md Simulations ◽  
Membrane Transporter ◽  
Biochemical Activity ◽  
Glycoprotein P ◽  
P Glycoprotein ◽  
Hydrolysis Activity

P-glycoprotein (P-gp) is a critical membrane transporter in the blood brain barrier (BBB) and is implicated in Alzheimer’s disease (AD). However, previous studies on the ability of P-gp to directly transport the Alzheimer’s associated amyloid-β (Aβ) protein have produced contradictory results. Here we use molecular dynamics (MD) simulations, transport substrate accumulation studies in cell culture, and biochemical activity assays to show that P-gp actively transports Aβ. We observed transport of Aβ40 and Aβ42 monomers by P-gp in explicit MD simulations of a putative catalytic cycle. In in vitro assays with P-gp overexpressing cells, we observed enhanced accumulation of fluorescently labeled Aβ42 in the presence of Tariquidar, a potent P-gp inhibitor. We also showed that Aβ42 stimulated the ATP hydrolysis activity of isolated P-gp in nanodiscs. Our findings expand the substrate profile of P-gp, and suggest that P-gp may contribute to the onset and progression of AD.

scholarly journals Overcoming P-Glycoprotein-Mediated Doxorubicin Resistance

2021 ◽  
Author(s):  
Suree Jianmongkol
Keyword(s):  
Cancer Cells ◽  
Multi Drug Resistance ◽  
Therapeutic Success ◽  
Glycoprotein P ◽  
Target Delivery ◽  
Doxorubicin Treatment ◽  
Doxorubicin Resistance ◽  
P Glycoprotein ◽  
Strategic Approach ◽  
Effective Level

Intracellular concentration of doxorubicin in target cancer cells is a major determinant of therapeutic success of doxorubicin-based regimens. As known, doxorubicin is a substrate of P-glycoprotein (P-gp), the drug efflux transporter in the ABC superfamily. High expression level of P-gp in cancer cells can prevent intracellular accumulation of doxorubicin up to its effective level, leading to doxorubicin resistance and treatment failure. Moreover, these P-gp-overexpressed cells display multi-drug resistance (MDR) phenotype. Regarding this, application of P-gp modulators (suppressor of P-gp activity and expression) is likely to reverse MDR and restore cell sensitivity to doxorubicin treatment. In searching for potential chemo-sensitizer against resistant cancer, a number of phytochemicals or dietary compounds have been studied extensively for their P-gp modulating effects. Furthermore, combination between doxorubicin and P-gp modulators (e.g., plant-derived compounds, siRNA) given through specific target delivery platforms have been an effective strategic approach for MDR reversal and restore doxorubicin effectiveness for cancer treatment.

scholarly journals The Effects of TiO2 Nanoparticles on Cisplatin Cytotoxicity in Cancer Cell Lines

2020 ◽  
Vol 21 (2) ◽  
pp. 605 ◽  
Author(s):  
Basma Salama ◽  
El-Said El-Sherbini ◽  
Gehad El-Sayed ◽  
Mohamed El-Adl ◽  
Koki Kanehira ◽  
...  
Keyword(s):  
Drug Resistance ◽  
Cancer Cells ◽  
Hepg2 Cells ◽  
Titanium Dioxide Nanoparticles ◽  
Membrane Receptors ◽  
Multi Drug Resistance ◽  
A431 Cells ◽  
Glycoprotein P ◽  
P Glycoprotein ◽  
Low Expression

There have been many studies on improving the efficacy of cisplatin and on identifying safe compounds that can overcome multi-drug resistance (MDR) acquired by cancer cells. Our previous research showed that polyethylene glycol-modified titanium dioxide nanoparticles (TiO2 PEG NPs) affect cell membrane receptors, resulting in their aggregation, altered localization and downregulation. TiO2 PEG NPs may affect P-glycoprotein (P-gp), a membrane efflux channel involved in MDR. In this study, we investigated the effect of TiO2 PEG NPs on cisplatin cytotoxicity. We used HepG2 cells, which highly express P-gp and A431 cells, which show low expression of P-gp. The results showed that 10 µg/mL 100 nm TiO2 PEG NPs increased intracellular cisplatin levels and cytotoxicity in HepG2 cells but not in A431 cells. TiO2 PEG NPs treatment decreased the expression level of P-gp in HepG2 cells. Our findings indicate that TiO2 PEG NPs enhance cisplatin cytotoxicity by down regulating P-gp and that TiO2 PEG NPs are promising candidates for inhibiting P-gp and reversing drug resistance acquired by cancer cells.

scholarly journals Novel features in the structure of P-glycoprotein (ABCB1) in the post-hydrolytic state as determined at 7.9Å resolution

2018 ◽  
Author(s):  
Nopnithi Thonghin ◽  
Richard F. Collins ◽  
Alessandro Barbieri ◽  
Talha Shafi ◽  
Alistair Siebert ◽  
...  
Keyword(s):  
Binding Sites ◽  
Drug Binding ◽  
Multi Drug Resistance ◽  
Binding Domains ◽  
Atp Binding Cassette Transporter ◽  
P Glycoprotein ◽  
Head Groups ◽  
Related Drug ◽  
Drug Binding Sites

AbstractP-glycoprotein (ABCB1) is a ATP-binding cassette transporter that plays an important role in the removal of drugs and xenobiotic compounds from the cell. It is also associated with multi-drug resistance in cancer. Here we report novel features of the cryo-EM-derived structure of P-glycoprotein in the post-hydrolytic state: The cytosolic nucleotide-binding domains (NBDs) are separated despite ADP remaining bound to the NBDs. Gaps in the TMDs that connect to the inner hydrophilic cavity are back-filled by detergent head-groups from the annular detergent micelle and are close to two regions predicted to delineate two pseudo-symmetry-related drug-binding sites. In this conformation, the (newly-resolved) N-terminal extension, NBD-TMD linker region and gap-filling detergents all appear to impede NBD dimerisation. We propose a model for the mechanism of action of the exporter where ATP will be bound to the protein for most of the time, consistent with the high physiological ATP concentrationsin vivo.

scholarly journals Caffeic Acid Attenuates Multi-Drug Resistance in Cancer Cells by Inhibiting Efflux Function of Human P-Glycoprotein

Molecules ◽  
2020 ◽  
Vol 25 (2) ◽  
pp. 247
Author(s):  
Yu-Ning Teng ◽  
Charles C.N. Wang ◽  
Wei-Chieh Liao ◽  
Yu-Hsuan Lan ◽  
Chin-Chuan Hung
Keyword(s):  
Atpase Activity ◽  
Caffeic Acid ◽  
Efflux Pump ◽  
Multi Drug Resistance ◽  
Drug Efflux ◽  
Promising Candidate ◽  
Glycoprotein P ◽  
P Glycoprotein ◽  
Calcein Am ◽  
Drug Efflux Pump

Multidrug resistance (MDR) is a complicated ever-changing problem in cancer treatment, and P-glycoprotein (P-gp), a drug efflux pump, is regarded as the major cause. In the way of developing P-gp inhibitors, natural products such as phenolic acids have gotten a lot of attention recently. The aim of the present study was to investigate the modulating effects and mechanisms of caffeic acid on human P-gp, as well as the attenuating ability on cancer MDR. Calcein-AM, rhodamine123, and doxorubicin were used to analyze the interaction between caffeic acid and P-gp, and the ATPase activity of P-gp was evaluated as well. Resistance reversing effects were revealed by SRB and cell cycle assay. The results indicated that caffeic acid uncompetitively inhibited rhodamine123 efflux and competitively inhibited doxorubicin efflux. In terms of P-gp ATPase activity, caffeic acid exhibited stimulation in both basal and verapamil-stimulated activity. The combination of chemo drugs and caffeic acid resulted in decreased IC50 in ABCB1/Flp-InTM-293 and KB/VIN, indicating that the resistance was reversed. Results of molecular docking suggested that caffeic acid bound to P-gp through GLU74 and TRY117 residues. The present study demonstrated that caffeic acid is a promising candidate for P-gp inhibition and cancer MDR attenuation.

scholarly journals Identification of multi-drug resistance gene (MDR1) in equine ileum

2006 ◽  
Vol 36 (1) ◽  
pp. 298-300
Author(s):  
Cláudio Corrêa Natalini ◽  
Renata Lehn Linardi
Keyword(s):  
Drug Resistance ◽  
Mdr1 Gene ◽  
Multi Drug Resistance ◽  
Drug Elimination ◽  
Glycoprotein P ◽  
Future Studies ◽  
Normal Tissues ◽  
P Glycoprotein ◽  
The Central Nervous System ◽  
The Impact

P-glycoprotein (P-gp) is a membrane transporter encoded in the Multi-drug Resistance (MDR1) gene expressed in several normal tissues and over expressed in tumor cells. P-gp was already identified in different species but not yet in equine. MDR1 gene and P-gp are able to interfere with bioavailability and disposition of several drugs, altering pharmacokinetic and pharmacodinamic of drugs. The presence of the MDR1 and P-gp in the central nervous system blocks the entry of certain drugs in this tissue and reduces drug absorption and enhances drug elimination when P-gp and MDR1 are presented in the gastrointestinal tract. This study showed that the MDR1 gene is present in equine ileum. Future studies on the impact of the P-glycoprotein encoded gene MDR1 on drugs pharmacologic effects in horses are granted.

scholarly journals Providing a molecular mechanism for P-glycoprotein; why would I bother?

2015 ◽  
Vol 43 (5) ◽  
pp. 995-1002 ◽  
Author(s):  
Richard Callaghan
Keyword(s):  
Cancer Cells ◽  
Molecular Mechanism ◽  
Conformational Changes ◽  
Efflux Pump ◽  
Structural Data ◽  
Multi Drug Resistance ◽  
P Glycoprotein ◽  
Complex Protein ◽  
Cytosolic Domains ◽  
Drug Efflux Pump

It is almost 40 years since the drug efflux pump P-glycoprotein (permeability glycoprotein or P-gp) was shown to confer multi-drug resistance in cancer cells. This protein has been one of the most extensively investigated transport proteins due to its intriguing mechanism and its affect in oncology. P-gp is known to interact with over 300 compounds and the ability to achieve this has not yet been revealed. Following the binding of substrate and nucleotide, a complex series of conformational changes in the membrane and cytosolic domains translocates substrate across the membrane. Despite over 30 years of biochemical investigation, the availability of structural data and a plethora of chemical tools to modulate its function, the molecular mechanism remains a mystery. In addition, overcoming its activity in resistant cancer cells has not been achieved in the clinic, thereby garnering some degree of pessimism in the field. This review highlights the progress that has been achieved in understanding this complex protein and the value of undertaking molecular studies.

Unsymmetric dihydropyridines bearing 2-pyridyl methyl carboxylate as modulators of P-glycoprotein; synthesis and biological evaluation in resistant and non-resistant cancer cells

2019 ◽  
Vol 97 (8) ◽  
pp. 603-614
Author(s):  
Maryam Nejati ◽  
Hossein Sadeghpour ◽  
Sara Ranjbar ◽  
Katayoun Javidnia ◽  
Najmeh Edraki ◽  
...  
Keyword(s):  
Cancer Cells ◽  
Human Cancer ◽  
Binding Mode ◽  
Biological Evaluation ◽  
Multi Drug Resistance ◽  
Glycoprotein P ◽  
Glycoprotein Synthesis ◽  
Human Cancer Cells ◽  
P Glycoprotein ◽  
Mdr Reversal

Multi-drug resistance (MDR) in cancer cells is often associated with overexpression of P-glycoprotein (P-gp or ABCB1 or MDR1); therefore, modulators of this transporter might be helpful in overcoming MDR. In this study, 16 novel unsymmetrical dihydropyridine (DHP) derivatives bearing 2-pyridyl methyl carboxylate at C3 and a nitroimidazole or nitrophenyl ring at C4 positions of the DHP ring were synthesized. Their cytotoxicity was tested against four human cancer cells by MTT assay. The reversal capacity of MDR was examined in P-gp overexpressing cells (MES-SA/DX5) by measuring the alteration of doxorubicin’s IC50 and performing flow cytometric determination of intracellular rhodamine 123 accumulation. The calcium channel blocking (CCB) activity, as a side effect of DHPs, was tested on the ileum of a guinea pig. Molecular docking was performed to explain the binding mode of compounds. Two derivatives, 4a and 4c, containing 4-nitrophenyl at C4 and possessing methyl (4a) and iso-propyl (4c) carboxylates at the C5 position of DHP core demonstrated superior cytotoxic and MDR reversal activities and lower CCB effect. Docking analysis confirmed the importance of the 4-nitrophenyl ring for P-gp inhibitory activity. Some of the synthesized DHP derivatives with considerable MDR reversal capacity could be promising compounds for further discovery of useful agents for management of drug resistant cancer.

Sign in / Sign up

Export Citation Format

Share Document