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1.
Aminul Islam Khan Jin Liu Prashanta Dutta 《Biochimica et Biophysica Acta (BBA)/General Subjects》2018,1862(5):1168-1179
Background
Transferrin and its receptors play an important role during the uptake and transcytosis of iron through blood-brain barrier (BBB) endothelial cells (ECs) to maintain iron homeostasis in BBB endothelium and brain. Any disruptions in the cell environment may change the distribution of transferrin receptors on the cell surface, which eventually alter the homeostasis and initiate neurodegenerative disorders. In this paper, we developed a comprehensive mathematical model that considers the necessary kinetics for holo-transferrin internalization and acidification, apo-transferrin recycling, and exocytosis of free iron and transferrin-bound iron through basolateral side of BBB ECs.Methods
Ordinary differential equations are formulated based on the first order reaction kinetics to model the iron transport considering their interactions with transferrin and transferrin receptors. Unknown kinetics rate constants are determined from experimental data by applying a non-linear optimization technique.Results
Using the estimated kinetic rate constants, the presented model can effectively reproduce the experimental data of iron transports through BBB ECs for many in-vitro studies. Model results also suggest that the BBB ECs can regulate the extent of the two possible iron transport pathways (free and transferrin-bound iron) by controlling the receptor expression, internalization of holo-transferrin-receptor complexes and acidification of holo-transferrin inside the cell endosomes.Conclusion
The comprehensive mathematical model described here can predict the iron transport through BBB ECs considering various possible routes from blood side to brain side. The model can also predict the transferrin and iron transport behavior in iron-enriched and iron-depleted cells, which has not been addressed in previous work. 相似文献2.
Greta Jarockyte Dominyka Dapkute Vitalijus Karabanovas Justinas V. Daugmaudis Feliksas Ivanauskas Ricardas Rotomskis 《Biochimica et Biophysica Acta (BBA)/General Subjects》2018,1862(4):914-923
Background
Monolayer cell cultures have been considered the most suitable technique for in vivo cellular experiments. However, a lot of cellular functions and responses that are present in natural tissues are lost in two-dimensional cell cultures. In this context, nanoparticle accumulation data presented in literature are often not accurate enough to predict behavior of nanoparticles in vivo. Cellular spheroids show a higher degree of morphological and functional similarity to the tissues.Methods
Accumulation and distribution of carboxylated CdSe/ZnS quantum dots (QDs), chosen as model nanoparticles, was investigated in cellular spheroids composed of different phenotype mammalian cells. The findings were compared with the results obtained in in vivo experiments with human tumor xenografts in immunodeficient mice. The diffusive transport model was used for theoretical nanoparticles distribution estimation.Results
QDs were accumulated only in cells, which were localized in the periphery of cellular spheroids. CdSe/ZnS QDs were shown to be stable and inert; they did not have any side-effects for cellular spheroids formation. Penetration of QDs in both cellular spheroids and in vivo tumor model was limited. The mathematical model confirmed the experimental results: nanoparticles penetrated only 25 μm into cellular spheroids after 24 h of incubation.Conclusions
Penetration of negatively charged nanoparticles is limited not only in tumor tissue, but also in cellular spheroids.General Significance
The results presented in this paper show the superior applicability of cellular spheroids to cell monolayers in the studies of the antitumor effect and penetration of nanomedicines. 相似文献3.
Chunggab Choi Hye Min Kim Jeeheun Shon Jiae Park Hyeong-Taek Kim Suk Ho Kang Seung-Hun Oh Nam Keun Kim Ok Joon Kim 《Cytotherapy》2018,20(6):820-829
Background
The blood-brain barrier (BBB) presents a significant challenge to the therapeutic efficacy of stem cells in chronic stroke. Various methods have been developed to increase BBB permeability, but these are associated with adverse effects and are, therefore, not clinically applicable. We recently identified that combination drug treatment of mannitol and temozolomide improved BBB permeability in vitro. Here, we investigated whether this combination could increase the effectiveness of stem cell treatment in an animal model of chronic ischemic stroke.Methods
Chronic stroke was induced in rats by middle cerebral artery occlusion (MCAo). After then, rats were administered human umbilical cord–derived mesenchymal stromal cells (hUC-MSCs) by intravenous injection with or without combination drug treatment of mannitol and temozolomide. To evaluate the therapeutic efficacy, behavioral and immunohistochemical tests were performed, and the differences among control, stem cell only, combination drug only and stem cell with combination drug treatment were analyzed.Results
Although no hUC-MSCs were detected in any group, treatment with stem cells and combination drug of mannitol and temozolomide increased the intracerebral delivery of hCD63-positive microvesicles compared with stem cell only treatment. Furthermore, treatment with stem cells and drug combination ameliorated behavioral deficits and increased bromodeoxyuridine-, doublecortin- and Reca-1–positive cells in the perilesional area as compared with other groups.Discussion
The combination drug treatment of mannitol and temozolomide allowed for the efficient delivery of hUC-MSC–derived microvesicles into the brain in a chronic stroke rat model. This attenuated behavioral deficits, likely by improving neural regeneration and angiogenesis. Thus, combination drug treatment of mannitol and temozolomide could be a novel therapeutic option for patients with chronic ischemic stroke. 相似文献4.
Ludmila A. Kasatkina Vitaliy P. Gumenyuk Eva M. Sturm Akos Heinemann Tytus Bernas Irene O. Trikash 《Biochimica et Biophysica Acta (BBA)/General Subjects》2018,1862(12):2701-2713
Background
Neurosecretion is the multistep process occurring in separate spatial and temporal cellular boundaries which complicates its comprehensive analysis. Most of the research are focused on one distinct stage of synaptic vesicle recycling. Here, we describe approaches for complex analysis of synaptic vesicle (SV) endocytosis and separate steps of exocytosis at the level of presynaptic bouton and highly purified SVs.Methods
Proposed fluorescence-based strategies and analysis of neurotransmitter transport provided the advantages in studies of exocytosis steps. We evaluated SV docking/tethering, their Ca2+-dependent fusion and release of neurotransmitters gamma-aminobutyric acid (GABA) and glutamate in two animal models.Results
Approaches enabled us to study: 1) endocytosis/Ca2+-dependent release of fluorescent carbon nanodots (CNDs) during stimulation of nerve terminals; 2) the action of levetiracetam, modulator of SV glycoprotein SV2, on fusion competence of SVs and stimulated release of GABA and glutamate; 3) impairments of several steps of neurosecretion under vitamin D3 deficiency.Conclusions
Our algorithm enabled us to verify the method validity for multidimensional analysis of SV turnover. By increasing SV docking and the size of readily releasable pool (RRP), levetiracetam is able to selectively enhance the stimulated GABA secretion in hippocampal neurons. Findings suggest that SV2 regulates RRP through impact on the number of docked/primed SVs.General significance
Methodology can be widely applied to study the stimulated neurosecretion in presynapse, regulation of SV docking, their Ca2+-dependent fusion with target membranes, quantitative analysis of expression of neuron-specific proteins, as well as for testing the efficiency of pre-selected designed neuroactive substances. 相似文献5.
Background
The present study it is part of the study of the applications of biocompatible nanoparticles in a biological environment. Nowadays, in fact, nanoparticles are making it possible to reach surprising results in the field of biomaterials, drug delivery and their transport in the blood flux, as the use of the contrast medium for medical imaging and to be injected in tumors before to apply radio and thermal therapy. Nanoparticles modify the chemical and physical properties of solids, liquids, and gases and in particular of physiological liquids, soft and hard biological tissues.Methods
The present article focalizes on the role of Au nanoparticles for biological and medical applications in which their insertion in cells, tissues, and organs may improve the diagnostic imaging contrast with traditional X-ray imaging and the absorbed doses due to radio- and thermal-therapies. Their injection in the tissue, in fact, increases the effective atomic number of the tissue, thus the increment of the electron density of the medium causes higher radiation LET (linear energy transfer) with the increment of released dose and major effects of radiotherapy expositions.Main findings
The present paper shows the possibility to generate spherical gold nanoparticles with an average diameter of about 5 nm, pure and not agglomerated, biocompatible, stable and without the addition of chemical agents, by laser ablation of gold material in water. The solution can be directly injected in the extracellular liquid of cell cultures or directly in the blood flux of mice to be transported inside the complex living system. Here it is accumulated in specific organs in which the up-take and decay can be measured using suitable images of fluorescence of the organs of the mouse.Conclusions
The aim of this research is to transport the nanoparticles in places where tissue disease exists and reduce their concentration in healthy tissues. This permit a better observation of the diseased tissues and their preparation as targeting for radio- and thermal-therapy to be applied to damage tumor cells saving healthy tissues. 相似文献6.
Background
To quantitatively compare in-vitro and in vivo membrane transport studies of targeted delivery, one needs characterization of the magnetically-induced mobility of superparamagnetic iron oxide nanoparticles (SPION). Flux densities, gradients, and nanoparticle properties were measured in order to quantify the magnetic force on the SPION in both an artificial cochlear round window membrane (RWM) model and the guinea pig RWM.Methods
Three-dimensional maps were created for flux density and magnetic gradient produced by a 24-well casing of 4.1 kilo-Gauss neodymium-iron-boron (NdFeB) disc magnets. The casing was used to pull SPION through a three-layer cell culture RWM model. Similar maps were created for a 4 inch (10.16 cm) cube 48 MGOe NdFeB magnet used to pull polymeric-nanoparticles through the RWM of anesthetized guinea pigs. Other parameters needed to compute magnetic force were nanoparticle and polymer properties, including average radius, density, magnetic susceptibility, and volume fraction of magnetite.Results
A minimum force of 5.04 × 10-16 N was determined to adequately pull nanoparticles through the in-vitro model. For the guinea pig RWM, the magnetic force on the polymeric nanoparticles was 9.69 × 10-20 N. Electron microscopy confirmed the movement of the particles through both RWM models.Conclusion
As prospective carriers of therapeutic substances, polymers containing superparamagnetic iron oxide nanoparticles were succesfully pulled through the live RWM. The force required to achieve in vivo transport was significantly lower than that required to pull nanoparticles through the in-vitro RWM model. Indeed very little force was required to accomplish measurable delivery of polymeric-SPION composite nanoparticles across the RWM, suggesting that therapeutic delivery to the inner ear by SPION is feasible.7.
Background
The computational methods provide condition for investigation related to the process of drug delivery, such as convection and diffusion of drug in extracellular matrices, drug extravasation from microvessels or to lymphatic vessels. The information of this process clarifies the mechanisms of drug delivery from the injection site to absorption by a solid tumor. In this study, an advanced numerical method is used to solve fluid flow and solute transport equations simultaneously to investigate the effect of tumor shape and size on drug delivery to solid tumor.Methods
The advanced mathematical model used in our previous work is further developed by adding solute transport equation to the governing equations. After applying appropriate boundary and initial conditions on tumor and surrounding tissue geometry, the element-based finite volume method is used for solving governing equations of drug delivery in solid tumor. Also, the effects of size and shape of tumor and some of tissue transport parameters such as effective pressure and hydraulic conductivity on interstitial fluid flow and drug delivery are investigated.Results
Sensitivity analysis shows that drug delivery in prolate shape is significantly better than other tumor shapes. Considering size effect, increasing tumor size decreases drug concentration in interstitial fluid. This study shows that dependency of drug concentration in interstitial fluid to osmotic and intravascular pressure is negligible.Conclusions
This study shows that among diffusion and convection mechanisms of drug transport, diffusion is dominant in most different tumor shapes and sizes. In tumors in which the convection has considerable effect, the drug concentration is larger than that of other tumors at the same time post injection.8.
Hua Deng Prashanta Dutta Jin Liu 《Biochimica et Biophysica Acta (BBA)/General Subjects》2018,1862(9):2104-2111
Background
Receptor dependent clathrin-mediated endocytosis (CME) is one of the most important endocytic pathways for the internalization of bioparticles into cells. During CME, the ligand-receptor interactions, development of clathrin-coated pit (CCP) and membrane evolution all act together to drive the internalization of bioparticles. In this work, we develop a stochastic computational model to investigate the CME based on the Metropolis Monte Carlo simulations.Methods
The model is based on the combination of a stochastic particle binding model with a membrane model. The energetic costs of membrane bending, CCP formation and ligand-receptor interactions are systematically linked together.Results
We implement our model to investigate the effects of particle size, ligand density and membrane stiffness on the overall process of CME from the drug delivery perspectives. Consistent with some experiments, our results show that the intermediate particle size and ligand density favor the particle internalization. Moreover, our results show that it is easier for a particle to enter a cell with softer membrane.Conclusions
The model presented here is able to provide mechanistic insights into CME and can be readily modified to include other important factors, such as actins. The predictions from the model will aid in the therapeutic design of intracellular/transcellular drug delivery and antiviral interventions. 相似文献9.
Alice Domenichini Aleksandra Adamska Marco Falasca 《Biochimica et Biophysica Acta (BBA)/General Subjects》2019,1863(1):52-60
Background
ABC transporters have attracted considerable attention for their function as drug transporters in a broad range of tumours and are therefore considered as major players in cancer chemoresistance. However, less attention has been focused on their potential role as active players in cancer development and progression.Scope of review
This review presents the evidence suggesting that ABC transporters might have a more active role in cancer other than the well known involvement in multidrug resistance and discusses the potential strategies to target each ABC transporter for a specific tumour setting.Major conclusions
Emerging evidence suggests that ABC transporters are able to transport bioactive molecules capable of playing key roles in tumour development. Characterization of the effects of these transporters in specific cancer settings opens the possibility for the development of personalized treatments.General significance
A more targeted approach of ABC transporters should be implemented that considers which specific transporter is playing a major role in a particular tumour setting in order to achieve a more successful outcome for ABC transporters inhibitors in cancer therapy. 相似文献10.
Background
Particle size is a key parameter for drug-delivery nanoparticle design. It is believed that the size of a nanoparticle may have important effects on its ability to overcome the transport barriers in biological tissues. Nonetheless, such effects remain poorly understood. Using a multiscale model, this work investigates particle size effects on the tissue distribution and penetration efficacy of drug-delivery nanoparticles.Results
We have developed a multiscale spatiotemporal model of nanoparticle transport in biological tissues. The model implements a time-adaptive Brownian Dynamics algorithm that links microscale particle-cell interactions and adhesion dynamics to tissue-scale particle dispersion and penetration. The model accounts for the advection, diffusion, and cellular uptakes of particles. Using the model, we have analyzed how particle size affects the intra-tissue dispersion and penetration of drug delivery nanoparticles. We focused on two published experimental works that investigated particle size effects in in vitro and in vivo tissue conditions. By analyzing experimental data reported in these two studies, we show that particle size effects may appear pronounced in an in vitro cell-free tissue system, such as collagen matrix. In an in vivo tissue system, the effects of particle size could be relatively modest. We provide a detailed analysis on how particle-cell interactions may determine distribution and penetration of nanoparticles in a biological tissue.Conclusion
Our work suggests that the size of a nanoparticle may play a less significant role in its ability to overcome the intra-tissue transport barriers. We show that experiments involving cell-free tissue systems may yield misleading observations of particle size effects due to the absence of advective transport and particle-cell interactions.11.
Beata Gąsowska-Bajger Yuki Nishigaya Krystyna Hirsz-Wiktorzak Anna Rybczyńska Toshimasa Yamazaki Hubert Wojtasek 《Biochimica et Biophysica Acta (BBA)/General Subjects》2018,1862(7):1626-1634
Background
A number of compounds, including ascorbic acid, catecholamines, flavonoids, p-diphenols and hydrazine derivatives have been reported to interfere with peroxidase-based medical diagnostic tests (Trinder reaction) but the mechanisms of these effects have not been fully elucidated.Methods
Reactions of bovine myeloperoxidase with o-dianisidine, bovine lactoperoxidase with ABTS and horseradish peroxidase with 4-aminoantipyrine/phenol in the presence of carbidopa, an anti-Parkinsonian drug, and other catechols, including l-dopa, were monitored spectrophotometrically and by measuring hydrogen peroxide consumption.Results
Chromophore formation in all three enzyme/substrate systems was blocked in the presence of carbidopa and other catechols. However, the rates of hydrogen peroxide consumption were not much affected. Irreversible enzyme inhibition was also insignificant.Conclusions
Tested compounds reduced the oxidation products or intermediates of model substrates thus preventing chromophore formation. This interference may affect interpretation of results of diagnostic tests in samples from patients with Parkinson's disease treated with carbidopa and l-dopa.General significance
This mechanism allows prediction of interference in peroxidase-based diagnostic tests for other compounds, including drugs and natural products. 相似文献12.
Peng Zhao Bo Chen Lushen Li Hao Wu Yan Li Baxter Shaneen Xi Zhan Ning Gu 《Biochimica et Biophysica Acta (BBA)/General Subjects》2019,1863(2):502-510
Background
Magnetic nanoparticles (MNPs) have been widely used in biomedical applications. Proper control of the duration of MNPs in circulation promises to improve further their applications, in particularly drug delivery. It is known that the uptake of tissue-associated MNPs is mainly carried out by macrophages. Yet, the molecular mechanism to control MNPs internalization in macrophages remains to be elusive. Missing-in-metastasis (MIM) is a scaffolding protein that is highly expressed in macrophages and regulates receptor-mediated endocytosis. We hypothesize that uptake of MNPs may also involve the function of MIM.Methods
We investigated the effect of MIM expression on the intracellular trafficking of MNPs by transmission electronic microscopy, flow cytometry, o-phenanthroline photometric analysis, Perl's staining, immunofluorescence microscopy and co-immunoprecipitation. To explore the molecular events in MIM-mediated MNPs uptake, we examined the effect of MNPs on the interaction of MIM with clathrin, Rab5 and Rab7.Results
Uptake of MNPs was significantly enhanced in cells overexpressing MIM. Upon exposure to MNPs, MIM was associated with clathrin light chain in endocytic vesicles and Rab7, a protein that regulates late endosomes. However, MNPs caused dissociation of MIM with Rab5, an early endosome-associated protein.Conclusions
MIM regulates internalization of MNPs via promoting their trafficking from plasma membrane to late endosomes.General significance
Our data unveiled a novel pathway which MNPs internalization and intracellular trafficking in macrophages. This new pathway may allow us to control the uptake of MNPs within cells by targeting MIM, thereby improving their medical applications. 相似文献13.
Yuka Torii Yoshihiko Kawano Hajime Sato Tamaki Fujimori Kazunori Sasaki Jun-ichi Kawada Osamu Takikawa Chai K. Lim Gilles J. Guillemin Yoshiaki Ohashi Yoshinori Ito 《Metabolomics : Official journal of the Metabolomic Society》2017,13(11):126
Introduction
Human herpesvirus 6 (HHV-6) is the second most common causative pathogen of acute encephalopathy in immunocompetent children in Japan. Identification of biomarkers associated the pathophysiology is desirable to monitor disease severity, progression, and prognosis.Objectives
To investigate potential biomarkers for HHV-6 encephalopathy, serum metabolome profiling was analyzed and candidate metabolites were investigated the function in the diseases.Methods
Pediatric patients with HHV-6 encephalopathy (n?=?8), febrile seizure (n?=?20), and febrile infection without febrile seizure (n?=?7) were enrolled in this study, and serum metabolites were identified and quantified. For further analysis, serum samples of HHV-6 infected patients were analyzed by absolute quantification assay for kynurenine (KYN) and quinolinic acid (QUIN) in a total of 38 patients with or without encephalopathy. An in vitro blood–brain barrier (BBB) model was used to evaluate the effect of KYN and QUIN on BBB integrity because BBB damage induces brain edema.Results
Metabolome profiling identified 159 metabolites in serum samples. The levels of KYN and QUIN, which belong to the tryptophan-KYN pathway, were significantly higher in the HHV-6 encephalopathy group than the other two groups. When quantified in the larger patient group, remarkably high levels of KYN and QUIN were observed exclusively in the encephalopathy group. Trans-endothelial electrical resistance of the BBB model was significantly decreased after QUIN treatment in culture.Conclusion
Metabolome analysis revealed that KYN and QUIN may be associated with the pathophysiology of HHV-6 encephalopathy. In particular, QUIN may damage BBB integrity.14.
Shreyasi Asthana Zaved Hazarika Parth Sarathi Nayak Jyoti Roy Anupam Nath Jha Bibekanand Mallick Suman Jha 《Biochimica et Biophysica Acta (BBA)/General Subjects》2019,1863(1):153-166
Background
Injection localized amyloidosis is one of the most prevalent disorders in type II diabetes mellitus (TIIDM) patients relying on insulin injections. Previous studies have reported that nanoparticles can play a role in the amyloidogenic process of proteins. Hence, the present study deals with the effect of zinc oxide nanoparticles (ZnONP) on the amyloidogenicity and cytotoxicity of insulin.Methods
ZnONP is synthesised and characterized using XRD, Zeta Sizer, UV-Visible spectroscope and TEM. The characterization is followed by ZnONP interaction with insulin, which is studied employing fluorescence spectroscopes, isothermal titration calorimetry and molecular dynamics simulations. The interaction leads insulin conformational rearrangement into amyloid-like fibril, which is studied using thioflavin T dye binding assay, circular dichroism spectroscopy and TEM, followed by cytotoxicity propensity using Alamar Blue dye reduction assay.Results
Insulin has very weak interaction with ZnONP interface. Insulin at studied concentration forms amorphous aggregates at physiological pH, whereas in presence of ZnONP interface amyloid-like fibrils are formed. While the amyloid-like fibrils are cytotoxic to MIN6 and THP-1 cell lines, insulin and ZnONP individual solutions and their fresh mixtures enhance the cells proliferation.Conclusions
The presence of ZnONP interface enhances insulin fibrillation at physiological pH by providing a favourable template for the nucleation and growth of insulin amyloids.General significance
The studied protein-nanoparticle system from protein conformational dynamics point of view throws caution over nanoparticle use in biological applications, especially in vivo applications, considering the amyloidosis a very slow but non-curable degenerative disease. 相似文献15.
Mingsan Miao Mengfan Peng Hongbao Chen Baosong Liu 《Saudi Journal of Biological Sciences》2019,26(3):582-588
Purpose
Explore the effect of Baihe Dihuang powder on chronic stress depression rat models.Methods
Chronic stress depression rat models were established with different stimuli for 21?days. At the same time, the drug was administered for 21 consecutive days. The animals were weighed once a week after the start of the formal experiment. On the second day after the end of drug administration, conduct sugar water consumption test and open-filed box experiment, and conduct behavioral observation; At the end of behavioral testing, blood was taken from the eyeball and plasma was separated to measure MDA level and erythrocyte SOD activity; Take brain for homogenate, then measure the contents of 5-HT, NE and DA in brain tissue homogenate; Take the thymus and spleen, stained with 10% formalin fixation, embedding and HE staining, then use microscope to observe the histopathological changes.Results
Chronic stress depression rats model replicated successfully. Each group of given drugs could increase the weight, the consumption of sugar water, and improve the behavioral score, increase erythrocytes SOD activity and decrease MDA level of plasma, increase the content of 5-HT, NE and DA of brain homogenate, and improve the pathological changes of thymus and spleen of chronic stress depression model animals.Conclusion
Chronic stress depression rat model replicates successfully. Baihe Dihuang powder can interfere chronic stress depression rats model through different action pathways. 相似文献16.
Background
Disruption to the blood brain barrier (BBB) is a leading factor associated with the development of postoperative cognitive dysfunction (POCD). Despite this, the underlying mechanism by which BBB disruption promotes POCD in the elderly population has not yet been not fully elucidated.Results
In this study, we established a POCD mice model using isoflurane, and observed the highly expressed occludin and claudin 5 in brain tissues concomitant with the increased enrichment of CD4 positive cells and NK cells in the hippocampus of POCD mice compared to normal and non-POCD control.Conclusions
Our data suggests that peripheral immune cells may participate in the inflammatory reaction within the hippocampus, following the administration of anesthesia via inhalation with the destruction of the blood-brain barrier.17.
Cinzia Tarsia Alberto Danielli Francesca Florini Paolo Cinelli Stefano Ciurli Barbara Zambelli 《Biochimica et Biophysica Acta (BBA)/General Subjects》2018,1862(10):2245-2253
Background
Helicobacter pylori is a bacterium strongly associated with gastric cancer. It thrives in the acidic environment of the gastric niche of large portions of the human population using a unique adaptive mechanism that involves the catalytic activity of the nickel-dependent enzyme urease. Targeting urease represents a key strategy for drug design and H. pylori eradication.Method
Here, we describe a novel method to screen, directly in the cellular environment, urease inhibitors. A ureolytic Escherichia coli strain was engineered by cloning the entire urease operon in an expression plasmid and used to test in-cell urease inhibition with a high-throughput colorimetric assay. A two-plasmid system was further developed to evaluate the ability of small peptides to block the protein interactions that lead to urease maturation.Results
The developed assay is a robust cellular model to test, directly in the cell environment, urease inhibitors. The efficacy of a co-expressed peptide to affect the interaction between UreF and UreD, two accessory proteins necessary for urease activation, was observed. This event involves a process that occurs through folding upon binding, pointing to the importance of intrinsically disordered hot spots in protein interfaces.Conclusions
The developed system allows the concomitant screening of a large number of drug candidates that interfere with the urease activity both at the level of the enzyme catalysis and maturation.General significance
As inhibition of urease has the potential of being a global antibacterial strategy for a large number of infections, this work paves the way for the development of new candidates for antibacterial drugs. 相似文献18.
Attilio Vittorio Vargiu Venkata Krishnan Ramaswamy Ivana Malvacio Giuliano Malloci Ulrich Kleinekathöfer Paolo Ruggerone 《Biochimica et Biophysica Acta (BBA)/General Subjects》2018,1862(4):836-845
Background
Efflux pumps of the Resistance-Nodulation-cell Division superfamily confer multi-drug resistance to Gram-negative bacteria. The most-studied polyspecific transporter belonging to this class is the inner-membrane trimeric antiporter AcrB of Escherichia coli. In previous studies, a functional rotation mechanism was proposed for its functioning, according to which the three monomers undergo concerted conformational changes facilitating the extrusion of substrates. However, the molecular determinants and the energetics of this mechanism still remain unknown, so its feasibility must be proven mechanistically.Methods
A computational protocol able to mimic the functional rotation mechanism in AcrB was developed. By using multi-bias molecular dynamics simulations we characterized the translocation of the substrate doxorubicin driven by conformational changes of the protein. In addition, we estimated for the first time the free energy profile associated to this process.Results
We provided a molecular view of the process in agreement with experimental data. Moreover, we showed that the conformational changes occurring in AcrB enable the formation of a layer of structured waters on the internal surface of the transport channel. This water layer, in turn, allows for a fairly constant hydration of the substrate, facilitating its diffusion over a smooth free energy profile.Conclusions
Our findings reveal a new molecular mechanism of polyspecific transport whereby water contributes by screening potentially strong substrate-protein interactions.General significance
We provided a mechanistic understanding of a fundamental process related to multi-drug transport. Our results can help rationalizing the behavior of other polyspecific transporters and designing compounds avoiding extrusion or inhibitors of efflux pumps. 相似文献19.
Fan Feng Qiyu Jiang Shuang Cao Yu Cao Ruisheng Li Lijun Shen Hua Zhu Tao Wang Lijun Sun Erguang Liang Huiwei Sun Yantao Chai Xiaojuan Li Genyan Liu Ruichang Yang Zhi Yang Yongping Yang Shaojie Xin Bo-an Li 《Biochimica et Biophysica Acta (BBA)/General Subjects》2018,1862(4):1017-1030
Background
Kinase inhibitor sorafenib is the most widely used drug for advanced HCC clinical treatment nowadays. However, sorafenib administration is only effective for a small portion of HCC patients, and the majority develop sorafenib-resistance during treatment. Thus, it is urgent to discover the endogenous mechanism and identify new pharmaceutical targets of sorafenib-resistance.Methods
Pregnane X receptor (PXR) was detected by immunohistochemistry and quantitative PCR. GST-pull down and LC-MS/MS was used to detect the interaction of PXR and Sorafenib. To test the properties of HCC tumor growth and metastasis, in vivo tumor explant model, FACS, trans-well assay, cell-survival inhibitory assay and Western blot were performed. In terms of mechanistic study, additional assays such as ChIP and luciferase reporter gene assay were applied.Results
In the present work, we found high PXR level in clinical specimens is related to the poor prognosis of Sorafenib treated patients. By the mechanistic studies, we show that sorafenib binds to PXR and activates PXR pathway, and by which HCC cells develop sorafenib-resistance via activating. Moreover, PXR overexpression helps HCC cells to persist to sorafenib treatment.Conclusion
This study reports the endogenous sorafenib-resistance mechanism in HCC cells, which offers an opportunity to design new therapeutic approaches for HCC treatment.General significance
PXR mediates sorafenib-resistance in HCC cells and targeting PXR can be a useful approach to facilitate HCC treatment. 相似文献20.
Huan He Juan Xu Wen Xie Qing-Lian Guo Feng-Lei Jiang Yi Liu 《Biochimica et Biophysica Acta (BBA)/General Subjects》2018,1862(3):501-512