1
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Müller WA, Sarkis JR, Marczak LDF, Muniz AR. Computational analysis of the simultaneous application of ultrasound and electric fields in a lipid bilayer. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2024; 1866:184364. [PMID: 38901662 DOI: 10.1016/j.bbamem.2024.184364] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2024] [Revised: 06/07/2024] [Accepted: 06/13/2024] [Indexed: 06/22/2024]
Abstract
The combined application of electric fields and ultrasonic waves has shown promise in controlling cell membrane permeability, potentially resulting in synergistic effects that can be explored in the biotechnology industry. However, further clarification on how these processes interact is still needed. The objective of the present study was to investigate the atomic-scale effects of these processes on a DPPC lipid bilayer using molecular dynamics simulations. For higher electric fields, capable of independently forming pores, the application of an ultrasonic wave in the absence of cavitation yielded no additional effects on pore formation. However, for lower electric fields, the reduction in bilayer thickness induced by the shock wave catalyzed the electroporation process, effectively shortening the mean path that water molecules must traverse to form pores. When cavitation was considered, synergistic effects were evident only if the wave alone was able to generate pores through the formation of a water nanojet. In these cases, sonoporation acted as a mean to focus the electroporation effects on the initial pore formed by the nanojet. This study contributes to a better understanding of the synergy between electric fields and ultrasonic waves and to an optimal selection of processing parameters in practical applications of these processes.
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Affiliation(s)
- Wagner Augusto Müller
- Universidade Federal do Rio Grande do Sul (UFRGS), Department of Chemical Engineering, Porto Alegre, RS, Brazil
| | - Júlia Ribeiro Sarkis
- Universidade Federal do Rio Grande do Sul (UFRGS), Department of Chemical Engineering, Porto Alegre, RS, Brazil
| | | | - André Rodrigues Muniz
- Universidade Federal do Rio Grande do Sul (UFRGS), Department of Chemical Engineering, Porto Alegre, RS, Brazil.
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2
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Clarke RJ. Electrostatic switch mechanisms of membrane protein trafficking and regulation. Biophys Rev 2023; 15:1967-1985. [PMID: 38192346 PMCID: PMC10771482 DOI: 10.1007/s12551-023-01166-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Accepted: 11/17/2023] [Indexed: 01/10/2024] Open
Abstract
Lipid-protein interactions are normally classified as either specific or general. Specific interactions refer to lipid binding to specific binding sites within a membrane protein, thereby modulating the protein's thermal stability or kinetics. General interactions refer to indirect effects whereby lipids affect membrane proteins by modulating the membrane's physical properties, e.g., its fluidity, thickness, or dipole potential. It is not widely recognized that there is a third distinct type of lipid-protein interaction. Intrinsically disordered N- or C-termini of membrane proteins can interact directly but nonspecifically with the surrounding membrane. Many peripheral membrane proteins are held to the cytoplasmic surface of the plasma membrane via a cooperative combination of two forces: hydrophobic anchoring and electrostatic attraction. An acyl chain, e.g., myristoyl, added post-translationally to one of the protein's termini inserts itself into the lipid matrix and helps hold peripheral membrane proteins onto the membrane. Electrostatic attraction occurs between positively charged basic amino acid residues (lysine and arginine) on one of the protein's terminal tails and negatively charged phospholipid head groups, such as phosphatidylserine. Phosphorylation of either serine or tyrosine residues on the terminal tails via regulatory protein kinases allows for an electrostatic switch mechanism to control trafficking of the protein. Kinase action reduces the positive charge on the protein's tail, weakening the electrostatic attraction and releasing the protein from the membrane. A similar mechanism regulates many integral membrane proteins, but here only electrostatic interactions are involved, and the electrostatic switch modulates protein activity by altering the stabilities of different protein conformational states.
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Affiliation(s)
- Ronald J. Clarke
- School of Chemistry, University of Sydney, Sydney, NSW 2006 Australia
- The University of Sydney Nano Institute, Sydney, NSW 2006 Australia
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3
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Youngworth R, Roux B. Simulating the Voltage-Dependent Fluorescence of Di-8-ANEPPS in a Lipid Membrane. J Phys Chem Lett 2023; 14:8268-8276. [PMID: 37676243 PMCID: PMC10510438 DOI: 10.1021/acs.jpclett.3c01257] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Accepted: 08/25/2023] [Indexed: 09/08/2023]
Abstract
Voltage-sensitive fluorescent dyes such as di-8-ANEPPS (di-8-aminonaphthylethylenepyridinium propylsulfonate) are powerful tools to study biological membranes. Its fluorescence is affected by changes in the membrane potential and other factors, requiring extensive calibration to extract meaningful quantitative results. The amphiphilic di-8-ANEPPS molecule is expected to bind at the membrane-solution interface. However, atomic-level information is sparse about its position and orientation in the membrane, especially in regards to how the latter dynamically fluctuates to affect the observed fluorescence. In the present work, molecular dynamics simulations of the ground and excited states of di-8-ANEPPS embedded in a DPPC membrane as represented by classical force fields were used to investigate how the fluorescence is affected by externally applied potential. The calculations reproduce the shifts in the wavelength of emission as a function of voltage that are observed experimentally, indicating that the approach can help better understand the various factors that can affect the fluorescence of membrane-bound dyes.
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Affiliation(s)
- Rachael Youngworth
- Department
of Chemistry, The University of Chicago, 5735 S. Ellis Avenue, Chicago, Illinois 60637, United States
| | - Benoît Roux
- Department
of Biochemistry and Molecular Biology, The
University of Chicago, 929 E. 57th Street W225, Chicago, Illinois 60637, United States
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4
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Disalvo A, Frias MA. Surface Characterization of Lipid Biomimetic Systems. MEMBRANES 2021; 11:membranes11110821. [PMID: 34832050 PMCID: PMC8621788 DOI: 10.3390/membranes11110821] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 10/21/2021] [Accepted: 10/21/2021] [Indexed: 11/16/2022]
Abstract
Zeta potential and dipole potential measures are direct operational methodologies to determine the adsorption, insertion and penetration of ions, amphipathic and neutral compounds into the membranes of cells and model systems. From these results, the contribution of charged and dipole groups can be deduced. However, although each method may give apparent affinity or binding constants, care should be taken to interpret them in terms of physical meaning because they are not independent properties. On the base of a recent model in which the lipid bilayer is considered as composed by two interphase regions at each side of the hydrocarbon core, this review describes how dipole potential and zeta potential are correlated due to water reorganization. From this analysis, considering that in a cell the interphase region the membrane extends to the cell interior or overlaps with the interphase region of another supramolecular structure, the correlation of dipole and electrostatic forces can be taken as responsible of the propagation of perturbations between membrane and cytoplasm and vice versa. Thus, this picture gives the membrane a responsive character in addition to that of a selective permeability barrier when integrated to a complex system.
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5
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Chen ST, Li Y, He SY, Zhou P, Lu J, Gu N. Microscopic Volta potential difference on metallic surface promotes the osteogenic differentiation and proliferation of human mesenchymal stem cells. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2021; 128:112325. [PMID: 34474876 DOI: 10.1016/j.msec.2021.112325] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Revised: 06/29/2021] [Accepted: 07/12/2021] [Indexed: 11/25/2022]
Abstract
Endogenous microscopic electric cues play an essential role in bone's remodeling and self-repair. Modulating the extracellular electrical environment, by means of external electric stimulation or changing surface potential of implants, was manifested to facilitate the osteointegration. The microscopic potential difference, originating from heterogeneous microstructures of materials, may mimic the endogenous electric signals to stimulate surrounding cells. In this study, the spark-plasma sintered Ti/Ta hybrid metal was fabricated and utilized to realize a surface microscopic potential difference at the same magnitude as endogenous potentials. Activated by the electric stimulation, the mesenchymal stem cells exhibited the anisotropic and polygonal cellular morphology on the Ti/Ta hybrid metal. The microscopic electric potential difference coordinated the cells proliferation on the subsequent days. Moreover, the results showed that the osteo-lineage differentiation on Ti/Ta hybrid metal were in vitro boosted over the control groups. Tailoring microstructures of material to obtain a reasonable electric microenvironment may be a necessary principle to achieve more favorable cell responses to implants, suggesting an extra degree of freedom in bone-repairing material design.
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Affiliation(s)
- Shi-Ting Chen
- State Key Laboratory of Bioelectronics, Jiangsu Key Laboratory for Biomaterials and Devices, School of Biological Science & Medical Engineering, Southeast University, Nanjing 210096, China
| | - Yan Li
- State Key Laboratory of Bioelectronics, Jiangsu Key Laboratory for Biomaterials and Devices, School of Biological Science & Medical Engineering, Southeast University, Nanjing 210096, China
| | - Si-Yuan He
- State Key Laboratory of Bioelectronics, Jiangsu Key Laboratory for Biomaterials and Devices, School of Biological Science & Medical Engineering, Southeast University, Nanjing 210096, China.
| | - Ping Zhou
- State Key Laboratory of Bioelectronics, Jiangsu Key Laboratory for Biomaterials and Devices, School of Biological Science & Medical Engineering, Southeast University, Nanjing 210096, China
| | - Jian Lu
- Department of Mechanical Engineering, City University of Hong Kong, Hong Kong, China
| | - Ning Gu
- State Key Laboratory of Bioelectronics, Jiangsu Key Laboratory for Biomaterials and Devices, School of Biological Science & Medical Engineering, Southeast University, Nanjing 210096, China.
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6
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State dependent effects on the frequency response of prestin's real and imaginary components of nonlinear capacitance. Sci Rep 2021; 11:16149. [PMID: 34373481 PMCID: PMC8352928 DOI: 10.1038/s41598-021-95121-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Accepted: 07/21/2021] [Indexed: 11/20/2022] Open
Abstract
The outer hair cell (OHC) membrane harbors a voltage-dependent protein, prestin (SLC26a5), in high density, whose charge movement is evidenced as a nonlinear capacitance (NLC). NLC is bell-shaped, with its peak occurring at a voltage, Vh, where sensor charge is equally distributed across the plasma membrane. Thus, Vh provides information on the conformational state of prestin. Vh is sensitive to membrane tension, shifting to positive voltage as tension increases and is the basis for considering prestin piezoelectric (PZE). NLC can be deconstructed into real and imaginary components that report on charge movements in phase or 90 degrees out of phase with AC voltage. Here we show in membrane macro-patches of the OHC that there is a partial trade-off in the magnitude of real and imaginary components as interrogation frequency increases, as predicted by a recent PZE model (Rabbitt in Proc Natl Acad Sci USA 17:21880–21888, 2020). However, we find similar behavior in a simple 2-state voltage-dependent kinetic model of prestin that lacks piezoelectric coupling. At a particular frequency, Fis, the complex component magnitudes intersect. Using this metric, Fis, which depends on the frequency response of each complex component, we find that initial Vh influences Fis; thus, by categorizing patches into groups of different Vh, (above and below − 30 mV) we find that Fis is lower for the negative Vh group. We also find that the effect of membrane tension on complex NLC is dependent, but differentially so, on initial Vh. Whereas the negative group exhibits shifts to higher frequencies for increasing tension, the opposite occurs for the positive group. Despite complex component trade-offs, the low-pass roll-off in absolute magnitude of NLC, which varies little with our perturbations and is indicative of diminishing total charge movement, poses a challenge for a role of voltage-driven prestin in cochlear amplification at very high frequencies.
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7
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Tapia J, Vera N, Aguilar J, González M, Sánchez SA, Coelho P, Saavedra C, Staforelli J. Correlated flickering of erythrocytes membrane observed with dual time resolved membrane fluctuation spectroscopy under different D-glucose concentrations. Sci Rep 2021; 11:2429. [PMID: 33510337 PMCID: PMC7844050 DOI: 10.1038/s41598-021-82018-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Accepted: 01/11/2021] [Indexed: 01/30/2023] Open
Abstract
A correlated human red blood cell membrane fluctuation dependent on D-glucose concentration was found with dual time resolved membrane fluctuation spectroscopy (D-TRMFS). This new technique is a modified version of the dual optical tweezers method that has been adapted to measure the mechanical properties of red blood cells (RBCs) at distant membrane points simultaneously, enabling correlation analysis. Mechanical parameters under different D-glucose concentrations were obtained from direct membrane flickering measurements, complemented with membrane fluidity measurements using Laurdan Generalized Polarization (GP) Microscopy. Our results show an increase in the fluctuation amplitude of the lipid bilayer, and a decline in tension value, bending modulus and fluidity as D-glucose concentration increases. Metabolic mechanisms are proposed as explanations for the results.
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Affiliation(s)
- J Tapia
- Departamento de Física, Facultad de Ciencias Físicas y Matemáticas, Universidad de Concepción, Concepción, Chile
| | - N Vera
- Departamento de Física, Facultad de Ciencias Físicas y Matemáticas, Universidad de Concepción, Concepción, Chile
| | - Joao Aguilar
- Departamento de Polímeros, Facultad de Ciencias Químicas, Universidad de Concepción, Concepción, Chile
| | - M González
- Laboratorio de Investigación Materno-Fetal (LIMaF), Departamento de Obstetricia y Ginecología, Facultad de Medicina, Universidad de Concepción, Concepción, Chile
| | - S A Sánchez
- Departamento de Polímeros, Facultad de Ciencias Químicas, Universidad de Concepción, Concepción, Chile
| | - P Coelho
- Facultad de Ingeniería y Tecnología, Universidad San Sebastián, Lientur 1457, 4080871, Concepción, Chile
| | - C Saavedra
- Departamento de Física, Facultad de Ciencias Físicas y Matemáticas, Universidad de Concepción, Concepción, Chile
| | - J Staforelli
- Departamento de Física, Facultad de Ciencias Físicas y Matemáticas, Universidad de Concepción, Concepción, Chile.
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8
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Liu C, Gao X, Yuan J, Zhang R. Advances in the development of fluorescence probes for cell plasma membrane imaging. Trends Analyt Chem 2020. [DOI: 10.1016/j.trac.2020.116092] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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9
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Filipe HAL, Moreno MJ, Loura LMS. The Secret Lives of Fluorescent Membrane Probes as Revealed by Molecular Dynamics Simulations. Molecules 2020; 25:E3424. [PMID: 32731549 PMCID: PMC7435664 DOI: 10.3390/molecules25153424] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 07/23/2020] [Accepted: 07/25/2020] [Indexed: 12/15/2022] Open
Abstract
Fluorescent probes have been employed for more than half a century to study the structure and dynamics of model and biological membranes, using spectroscopic and/or microscopic experimental approaches. While their utilization has led to tremendous progress in our knowledge of membrane biophysics and physiology, in some respects the behavior of bilayer-inserted membrane probes has long remained inscrutable. The location, orientation and interaction of fluorophores with lipid and/or water molecules are often not well known, and they are crucial for understanding what the probe is actually reporting. Moreover, because the probe is an extraneous inclusion, it may perturb the properties of the host membrane system, altering the very properties it is supposed to measure. For these reasons, the need for independent methodologies to assess the behavior of bilayer-inserted fluorescence probes has been recognized for a long time. Because of recent improvements in computational tools, molecular dynamics (MD) simulations have become a popular means of obtaining this important information. The present review addresses MD studies of all major classes of fluorescent membrane probes, focusing in the period between 2011 and 2020, during which such work has undergone a dramatic surge in both the number of studies and the variety of probes and properties accessed.
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Affiliation(s)
- Hugo A. L. Filipe
- Chemistry Department, Coimbra Chemistry Center, Faculty of Sciences and Technology, University of Coimbra, 3004-535 Coimbra, Portugal;
| | - Maria João Moreno
- Coimbra Chemistry Center and CNC—Center for Neuroscience and Cell Biology, Chemistry Department, Faculty of Sciences and Technology, University of Coimbra, 3004-535 Coimbra, Portugal;
| | - Luís M. S. Loura
- Coimbra Chemistry Center and CNC—Center for Neuroscience and Cell Biology, Faculty of Pharmacy, University of Coimbra, 3000-548 Coimbra, Portugal
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10
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Caglar M, Pandya R, Xiao J, Foster SK, Divitini G, Chen RYS, Greenham NC, Franze K, Rao A, Keyser UF. All-Optical Detection of Neuronal Membrane Depolarization in Live Cells Using Colloidal Quantum Dots. NANO LETTERS 2019; 19:8539-8549. [PMID: 31686516 PMCID: PMC7007274 DOI: 10.1021/acs.nanolett.9b03026] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Revised: 11/05/2019] [Indexed: 05/30/2023]
Abstract
Luminescent semiconductor quantum dots (QDs) have recently been suggested as novel probes for imaging and sensing cell membrane voltages. However, a key bottleneck for their development is a lack of techniques to assess QD responses to voltages generated in the aqueous electrolytic environments typical of biological systems. Even more generally, there have been relatively few efforts to assess the response of QDs to voltage changes in live cells. Here, we develop a platform for monitoring the photoluminescence (PL) response of QDs under AC and DC voltage changes within aqueous ionic environments. We evaluate both traditional CdSe/CdS and more biologically compatible InP/ZnS QDs at a range of ion concentrations to establish their PL/voltage characteristics on chip. Wide-field, few-particle PL measurements with neuronal cells show the QDs can be used to track local voltage changes with greater sensitivity (ΔPL up to twice as large) than state-of-the-art calcium imaging dyes, making them particularly appealing for tracking subthreshold events. Additional physiological observation studies showed that while CdSe/CdS dots have greater PL responses on membrane depolarization, their lower cytotoxicity makes InP/ZnS far more suitable for voltage sensing in living systems. Our results provide a methodology for the rational development of QD voltage sensors and highlight their potential for imaging changes in cell membrane voltage.
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Affiliation(s)
- Mustafa Caglar
- Department
of Physics, Cavendish Laboratory, University
of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - Raj Pandya
- Department
of Physics, Cavendish Laboratory, University
of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - James Xiao
- Department
of Physics, Cavendish Laboratory, University
of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - Sarah K. Foster
- Department
of Physiology, Development, and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3DY, United Kingdom
| | - Giorgio Divitini
- Department
of Materials Science and Metallurgy, University
of Cambridge, Cambridge CB3 0FS, United Kingdom
| | - Richard Y. S. Chen
- Department
of Physics, Cavendish Laboratory, University
of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - Neil C. Greenham
- Department
of Physics, Cavendish Laboratory, University
of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - Kristian Franze
- Department
of Physiology, Development, and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3DY, United Kingdom
| | - Akshay Rao
- Department
of Physics, Cavendish Laboratory, University
of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - Ulrich F. Keyser
- Department
of Physics, Cavendish Laboratory, University
of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
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11
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Zhao L, Gao X, Zhuang J, Wallen M, Leng S, Xu F. Prolongation of bronchopulmonary C-fiber-mediated apnea by prenatal nicotinic exposure in rat pups: role of 5-HT 3 receptors. FASEB J 2019; 33:10731-10741. [PMID: 31251077 PMCID: PMC6766661 DOI: 10.1096/fj.201900279rr] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Accepted: 06/04/2019] [Indexed: 01/30/2023]
Abstract
Prenatal nicotinic exposure (PNE) reportedly sensitizes bronchopulmonary C-fibers (PCFs) and prolongs PCF-mediated apnea in rat pups, contributing to the pathogenesis of sudden infant death syndrome. Serotonin, or 5-hydroxytryptamine (5-HT), induces apnea via acting on 5-HT receptor 3 (5-HT3R) in PCFs, and among the 5-HT3R subunits, 5-HT3B is responsible for shortening the decay time of 5-HT3R-mediated currents. We examined whether PNE would promote pulmonary 5-HT secretion and prolong the apnea mediated by 5-HT3Rs in PCFs via affecting the 5-HT3B subunit. To this end, the following variables were compared between the control and PNE rat pups: 1) the 5-HT content in bronchoalveolar lavage fluid, 2) the apneic response to the right atrial bolus injection of phenylbiguanide (a 5-HT3R agonist) before and after PCF inactivation, 3) 5-HT3R currents and the stimulus threshold of the action currents of vagal pulmonary C-neurons, and 4) the immunoreactivity (IR) and mRNA expression of 5-HT3A and 5-HT3B in these neurons. Our results showed that PNE up-regulated the pulmonary 5-HT concentration and strengthened the PCF 5-HT3R-mediated apnea. PNE significantly facilitated neural excitability by shortening the decay time of 5-HT3R currents, lowering the stimulus threshold, and increasing 5-HT3B IR. In summary, PNE prolongs the apnea mediated by 5-HT3Rs in PCFs, likely by increasing 5-HT3B subunits to enhance the excitability of 5-HT3 channels.-Zhao, L., Gao, X., Zhuang, J., Wallen, M., Leng, S., Xu, F. Prolongation of bronchopulmonary C-fiber-mediated apnea by prenatal nicotinic exposure in rat pups: role of 5-HT3 receptors.
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MESH Headings
- Animals
- Animals, Newborn
- Apnea/etiology
- Apnea/genetics
- Apnea/physiopathology
- Biguanides/administration & dosage
- Bronchoalveolar Lavage Fluid/chemistry
- Disease Models, Animal
- Female
- Humans
- Infant, Newborn
- Lung/drug effects
- Lung/innervation
- Lung/physiopathology
- Male
- Nerve Fibers, Unmyelinated/drug effects
- Nerve Fibers, Unmyelinated/physiology
- Nicotine/administration & dosage
- Nicotine/toxicity
- Pregnancy
- Prenatal Exposure Delayed Effects/etiology
- Prenatal Exposure Delayed Effects/physiopathology
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Rats
- Rats, Sprague-Dawley
- Receptors, Serotonin, 5-HT3/genetics
- Receptors, Serotonin, 5-HT3/physiology
- Serotonin/metabolism
- Serotonin 5-HT3 Receptor Agonists/administration & dosage
- Sudden Infant Death/etiology
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Affiliation(s)
- Lei Zhao
- Pathophysiological Program, Lovelace Respiratory Research Institute, Albuquerque, New Mexico, USA
| | - Xiuping Gao
- Pathophysiological Program, Lovelace Respiratory Research Institute, Albuquerque, New Mexico, USA
| | - Jianguo Zhuang
- Pathophysiological Program, Lovelace Respiratory Research Institute, Albuquerque, New Mexico, USA
| | - Morgan Wallen
- Department of Arts and Sciences, University of Tennessee, Knoxville, Tennessee, USA
| | - Shuguang Leng
- Pathophysiological Program, Lovelace Respiratory Research Institute, Albuquerque, New Mexico, USA
| | - Fadi Xu
- Pathophysiological Program, Lovelace Respiratory Research Institute, Albuquerque, New Mexico, USA
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12
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Marzuoli I, Margreitter C, Fraternali F. Lipid Head Group Parameterization for GROMOS 54A8: A Consistent Approach with Protein Force Field Description. J Chem Theory Comput 2019; 15:5175-5193. [PMID: 31433640 PMCID: PMC7377650 DOI: 10.1021/acs.jctc.9b00509] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
![]()
Membranes
are a crucial component of both bacterial and mammalian
cells, being involved in signaling, transport, and compartmentalization.
This versatility requires a variety of lipid species to tailor the
membrane’s behavior as needed, increasing the complexity of
the system. Molecular dynamics simulations have been successfully
applied to study model membranes and their interactions with proteins,
elucidating some crucial mechanisms at the atomistic detail and thus
complementing experimental techniques. An accurate description of
the functional interplay of the diverse membrane components crucially
depends on the selected parameters that define the adopted force field.
A coherent parameterization for lipids and proteins is therefore needed.
In this work, we propose and validate new lipid head group parameters
for the GROMOS 54A8 force field, making use of recently published
parametrizations for key chemical moieties present in lipids. We make
use additionally of a new canonical set of partial charges for lipids,
chosen to be consistent with the parameterization of soluble molecules
such as proteins. We test the derived parameters on five phosphocholine
model bilayers, composed of lipid patches four times larger than the
ones used in previous studies, and run 500 ns long simulations of
each system. Reproduction of experimental data like area per lipid
and deuterium order parameters is good and comparable with previous
parameterizations, as well as the description of liquid crystal to
gel-phase transition. On the other hand, the orientational behavior
of the head groups is more realistic for this new parameter set, and
this can be crucial in the description of interactions with other
polar molecules. For that reason, we tested the interaction of the
antimicrobial peptide lactoferricin with two model membranes showing
that the new parameters lead to a weaker peptide–membrane binding
and give a more realistic outcome in comparing binding to antimicrobial
versus mammal membranes.
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Affiliation(s)
- Irene Marzuoli
- Randall Centre for Cell and Molecular Biology , King's College London , London SE1 1UL , U.K
| | - Christian Margreitter
- Randall Centre for Cell and Molecular Biology , King's College London , London SE1 1UL , U.K
| | - Franca Fraternali
- Randall Centre for Cell and Molecular Biology , King's College London , London SE1 1UL , U.K
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13
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Abstract
The investigation of lipid films for the construction of biosensors has recently given the opportunity to manufacture devices to selectively detect a wide range of food toxicants, environmental pollutants, and compounds of clinical interest. Biosensor miniaturization using nanotechnological tools has provided novel routes to immobilize various “receptors” within the lipid film. This chapter reviews and exploits platforms in biosensors based on lipid membrane technology that are used in food, environmental, and clinical chemistry to detect various toxicants. Examples of applications are described with an emphasis on novel systems, new sensing techniques, and nanotechnology-based transduction schemes. The compounds that can be monitored are insecticides, pesticides, herbicides, metals, toxins, antibiotics, microorganisms, hormones, dioxins, etc.
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14
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Goujon A, Straková K, Sakai N, Matile S. Streptavidin interfacing as a general strategy to localize fluorescent membrane tension probes in cells. Chem Sci 2019; 10:310-319. [PMID: 30713639 PMCID: PMC6333237 DOI: 10.1039/c8sc03620a] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Accepted: 10/09/2018] [Indexed: 12/12/2022] Open
Abstract
To image the mechanical properties of biological membranes, twisted push-pull mechanophores that respond to membrane tension by planarization in the ground state have been introduced recently. For their application in biological systems, these so-called fluorescent flippers will have to be localized to specific environments of cellular membranes. In this report, we explore streptavidin as a versatile connector between biotinylated flipper probes and biotinylated targets. Fluorescence spectroscopy and microscopy with LUVs and GUVs reveal the specific conditions needed for desthiobiotin-loaded streptavidin to deliver biotinylated flippers selectively to biotinylated membranes. Selectivity for biotinylated plasma membranes is also observed in HeLa cells, confirming the compatibility of this strategy with biological systems. Streptavidin interfacing does not affect the mechanosensitivity of the flipper probes, red shift in the excitation maximum and fluorescence lifetime increase with membrane order and tension, as demonstrated, inter alia, using FLIM.
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Affiliation(s)
- Antoine Goujon
- School of Chemistry and Biochemistry , National Centre of Competence in Research (NCCR) Chemical Biology , University of Geneva , Geneva , Switzerland . ; http://www.unige.ch/sciences/chiorg/matile/
| | - Karolína Straková
- School of Chemistry and Biochemistry , National Centre of Competence in Research (NCCR) Chemical Biology , University of Geneva , Geneva , Switzerland . ; http://www.unige.ch/sciences/chiorg/matile/
| | - Naomi Sakai
- School of Chemistry and Biochemistry , National Centre of Competence in Research (NCCR) Chemical Biology , University of Geneva , Geneva , Switzerland . ; http://www.unige.ch/sciences/chiorg/matile/
| | - Stefan Matile
- School of Chemistry and Biochemistry , National Centre of Competence in Research (NCCR) Chemical Biology , University of Geneva , Geneva , Switzerland . ; http://www.unige.ch/sciences/chiorg/matile/
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15
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Effect of Cholesterol on the Dipole Potential of Lipid Membranes. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1115:135-154. [DOI: 10.1007/978-3-030-04278-3_6] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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16
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Colom A, Derivery E, Soleimanpour S, Tomba C, Molin MD, Sakai N, González-Gaitán M, Matile S, Roux A. A fluorescent membrane tension probe. Nat Chem 2018; 10:1118-1125. [PMID: 30150727 PMCID: PMC6197433 DOI: 10.1038/s41557-018-0127-3] [Citation(s) in RCA: 280] [Impact Index Per Article: 46.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Accepted: 07/25/2018] [Indexed: 12/24/2022]
Abstract
Cells and organelles are delimited by lipid bilayers in which high deformability is essential to many cell processes, including motility, endocytosis and cell division. Membrane tension is therefore a major regulator of the cell processes that remodel membranes, albeit one that is very hard to measure in vivo. Here we show that a planarizable push-pull fluorescent probe called FliptR (fluorescent lipid tension reporter) can monitor changes in membrane tension by changing its fluorescence lifetime as a function of the twist between its fluorescent groups. The fluorescence lifetime depends linearly on membrane tension within cells, enabling an easy quantification of membrane tension by fluorescence lifetime imaging microscopy. We further show, using model membranes, that this linear dependency between lifetime of the probe and membrane tension relies on a membrane-tension-dependent lipid phase separation. We also provide calibration curves that enable accurate measurement of membrane tension using fluorescence lifetime imaging microscopy.
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Affiliation(s)
- Adai Colom
- Biochemistry Department, University of Geneva, Geneva, Switzerland
- Swiss National Centre for Competence in Research Programme Chemical Biology, Geneva, Switzerland
- School of Chemistry and Biochemistry, University of Geneva, Geneva, Switzerland
| | - Emmanuel Derivery
- Biochemistry Department, University of Geneva, Geneva, Switzerland
- Swiss National Centre for Competence in Research Programme Chemical Biology, Geneva, Switzerland
- School of Chemistry and Biochemistry, University of Geneva, Geneva, Switzerland
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, UK
| | - Saeideh Soleimanpour
- Swiss National Centre for Competence in Research Programme Chemical Biology, Geneva, Switzerland
- School of Chemistry and Biochemistry, University of Geneva, Geneva, Switzerland
| | - Caterina Tomba
- Biochemistry Department, University of Geneva, Geneva, Switzerland
- School of Chemistry and Biochemistry, University of Geneva, Geneva, Switzerland
| | - Marta Dal Molin
- Swiss National Centre for Competence in Research Programme Chemical Biology, Geneva, Switzerland
- School of Chemistry and Biochemistry, University of Geneva, Geneva, Switzerland
| | - Naomi Sakai
- Swiss National Centre for Competence in Research Programme Chemical Biology, Geneva, Switzerland
- School of Chemistry and Biochemistry, University of Geneva, Geneva, Switzerland
| | - Marcos González-Gaitán
- Biochemistry Department, University of Geneva, Geneva, Switzerland
- Swiss National Centre for Competence in Research Programme Chemical Biology, Geneva, Switzerland
- School of Chemistry and Biochemistry, University of Geneva, Geneva, Switzerland
| | - Stefan Matile
- Swiss National Centre for Competence in Research Programme Chemical Biology, Geneva, Switzerland
- School of Chemistry and Biochemistry, University of Geneva, Geneva, Switzerland
| | - Aurélien Roux
- Biochemistry Department, University of Geneva, Geneva, Switzerland.
- Swiss National Centre for Competence in Research Programme Chemical Biology, Geneva, Switzerland.
- School of Chemistry and Biochemistry, University of Geneva, Geneva, Switzerland.
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17
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Sakai N, Matile S. Conjugated Polyimine Dynamers as Phase-Sensitive Membrane Probes. J Am Chem Soc 2018; 140:11438-11443. [PMID: 30156837 DOI: 10.1021/jacs.8b06668] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
In this report, dynamic polyimines are introduced as multifunctional sensors of lipid bilayer phases. Under mildly acidic conditions, self-condensation of push-pull amino formyl fluorenes into polyimines occurs in solid- or liquid-ordered phases but not in liquid-disordered phases of vesicular membranes. The obtained conjugated polymers are characterized by a progressive red shift of the absorption maxima, the appearance of exciton-coupled circular dichroism (CD) bands, and fluorescence quenching. These characteristics allow multiple modes of detection of membrane phases, which are known to change under membrane tension.
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Affiliation(s)
- Naomi Sakai
- Department of Organic Chemistry , University of Geneva , CH-1211 Geneva 4, Switzerland
| | - Stefan Matile
- Department of Organic Chemistry , University of Geneva , CH-1211 Geneva 4, Switzerland
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18
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Macchiagodena M, Del Frate G, Brancato G, Chandramouli B, Mancini G, Barone V. Computational study of the DPAP molecular rotor in various environments: from force field development to molecular dynamics simulations and spectroscopic calculations. Phys Chem Chem Phys 2018; 19:30590-30602. [PMID: 29115317 DOI: 10.1039/c7cp04688j] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Fluorescent molecular rotors (FMRs) belong to an important class of environment-sensitive dyes capable of acting as nanoprobes in the measurement of viscosity and polarity of their micro-environment. FMRs have found widespread applications in various research fields, ranging from analytical to biochemical sciences, for example in intracellular imaging studies or in volatile organic compound detection. Here, a computational investigation of a recently proposed FMR, namely 4-(diphenylamino)phthalonitrile (DPAP), in various chemical environments is presented. A purposely developed molecular mechanics force field is proposed and then applied to simulate the rotor in a high- and low-polar solvent (i.e., acetonitrile, tetrahydrofuran, o-xylene and cyclohexane), a polymer matrix and a lipid membrane. Subtle effects of the molecular interactions with the embedding medium, the structural fluctuations of the rotor and its rotational dynamics are analyzed in some detail. The results correlate with a previous work, thus supporting the reliability of the model, and provide further insights into the environment-specific properties of the dye. In particular, it is shown how molecular diffusion and rotational correlation times of the FMR are affected by the surrounding medium and how the molecular orientation of the dye becomes anisotropic once immersed in the lipid bilayer. Moreover, a qualitative correlation between the FMR rotational dynamics and the fluorescence lifetime is detected, a result in line with the observed viscosity dependence of its emission. Finally, optical absorption spectra are computed and successfully compared with their experimental counterparts.
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19
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Houang EM, Bates FS, Sham YY, Metzger JM. All-Atom Molecular Dynamics-Based Analysis of Membrane-Stabilizing Copolymer Interactions with Lipid Bilayers Probed under Constant Surface Tensions. J Phys Chem B 2017; 121:10657-10664. [PMID: 29049887 DOI: 10.1021/acs.jpcb.7b08938] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
An all-atom phospholipid bilayer and triblock copolymer model was developed for molecular dynamics (MD) studies. These were performed to investigate the mechanism of interaction between membrane-stabilizing triblock copolymer P188 and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylcholine (POPC) lipid bilayers under applied lateral surface tension (γ) to model membrane mechanical stress. Results showed that P188 insertion is driven by the hydrophobic poly(propylene oxide) (PPO) core and dependent on bilayer area per lipid. Moreover, insertion of P188 increased the bilayer's resistance to mechanical rupture, as observed by a significant increase in the absolute lateral pressure required to disrupt the bilayer. To further investigate the specific chemical features of P188 underlying membrane stabilizer function, a series of MD simulations with triblock copolymers of the same class as P188 but of varying chemical composition and sizes were performed. Results showed that triblock copolymer insertion into the lipid bilayer is dependent on overall copolymer hydrophobicity, with higher copolymer hydrophobicity requiring a reduced bilayer area per lipid ratio for insertion. Further analysis revealed that the effect of copolymer insertion on membrane mechanical integrity was also dependent on hydrophobicity. Here, P188 insertion significantly increased the absolute apparent lateral pressure required to rupture the POPC bilayer, thereby protecting the membrane against mechanical stress. In marked contrast, highly hydrophobic copolymers decreased the lateral pressure necessary for membrane rupture and thus rendering the membrane significantly more susceptible to mechanical stress. These new in silico findings align with recent experimental findings using synthetic lipid bilayers and in muscle cells in vitro and mouse models in vivo. Collectively, these data underscore the importance of PEO-PPO-PEO copolymer chemical composition in copolymer-based muscle membrane stabilization in vitro and in vivo. All-atom modeling with MD simulations holds promise for investigating novel copolymers with enhanced membrane interacting properties.
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Affiliation(s)
- Evelyne M Houang
- Integrative Biology and Physiology, University of Minnesota Medical School , Minneapolis, Minnesota 55455, United States
| | - Frank S Bates
- Department of Chemical Engineering and Materials Science, University of Minnesota , Minneapolis, Minnesota 55455, United States
| | - Yuk Y Sham
- Integrative Biology and Physiology, University of Minnesota Medical School , Minneapolis, Minnesota 55455, United States.,University of Minnesota Informatics Institute , Minneapolis, Minnesota 55455, United States.,Bioinformatics and Computational Biology Program, University of Minnesota , Minneapolis, Minnesota 55455, United States
| | - Joseph M Metzger
- Integrative Biology and Physiology, University of Minnesota Medical School , Minneapolis, Minnesota 55455, United States
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20
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Unraveling the mechanistic effects of electric field stimulation towards directing stem cell fate and function: A tissue engineering perspective. Biomaterials 2017; 150:60-86. [PMID: 29032331 DOI: 10.1016/j.biomaterials.2017.10.003] [Citation(s) in RCA: 194] [Impact Index Per Article: 27.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Revised: 09/27/2017] [Accepted: 10/02/2017] [Indexed: 02/06/2023]
Abstract
Electric field (EF) stimulation can play a vital role in eliciting appropriate stem cell response. Such an approach is recently being established to guide stem cell differentiation through osteogenesis/neurogenesis/cardiomyogenesis. Despite significant recent efforts, the biophysical mechanisms by which stem cells sense, interpret and transform electrical cues into biochemical and biological signals still remain unclear. The present review critically analyses the variety of EF stimulation approaches that can be employed to evoke appropriate stem cell response and also makes an attempt to summarize the underlying concepts of this notion, placing special emphasis on stem cell based tissue engineering and regenerative medicine. This review also discusses the major signaling pathways and cellular responses that are elicited by electric stimulation, including the participation of reactive oxygen species and heat shock proteins, modulation of intracellular calcium ion concentration, ATP production and numerous other events involving the clustering or reassembling of cell surface receptors, cytoskeletal remodeling and so on. The specific advantages of using external electric stimulation in different modalities to regulate stem cell fate processes are highlighted with explicit examples, in vitro and in vivo.
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21
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Siontorou CG, Nikoleli GP, Nikolelis DP, Karapetis SK. Artificial Lipid Membranes: Past, Present, and Future. MEMBRANES 2017; 7:E38. [PMID: 28933723 PMCID: PMC5618123 DOI: 10.3390/membranes7030038] [Citation(s) in RCA: 105] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Revised: 07/05/2017] [Accepted: 07/20/2017] [Indexed: 11/17/2022]
Abstract
The multifaceted role of biological membranes prompted early the development of artificial lipid-based models with a primary view of reconstituting the natural functions in vitro so as to study and exploit chemoreception for sensor engineering. Over the years, a fair amount of knowledge on the artificial lipid membranes, as both, suspended or supported lipid films and liposomes, has been disseminated and has helped to diversify and expand initial scopes. Artificial lipid membranes can be constructed by several methods, stabilized by various means, functionalized in a variety of ways, experimented upon intensively, and broadly utilized in sensor development, drug testing, drug discovery or as molecular tools and research probes for elucidating the mechanics and the mechanisms of biological membranes. This paper reviews the state-of-the-art, discusses the diversity of applications, and presents future perspectives. The newly-introduced field of artificial cells further broadens the applicability of artificial membranes in studying the evolution of life.
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Affiliation(s)
- Christina G Siontorou
- Laboratory of Simulation of Industrial Processes, Department of Industrial Management and Technology, School of Maritime and Industry, University of Piraeus, 18534 Piraeus, Greece.
| | - Georgia-Paraskevi Nikoleli
- Laboratory of Inorganic & Analytical Chemistry, School of Chemical Engineering, Department of Chemical Sciences, National Technical University of Athens, 15780 Athens, Greece.
| | - Dimitrios P Nikolelis
- Laboratory of Environmental Chemistry, Department of Chemistry, University of Athens, 15771 Athens, Greece.
| | - Stefanos K Karapetis
- Laboratory of Inorganic & Analytical Chemistry, School of Chemical Engineering, Department of Chemical Sciences, National Technical University of Athens, 15780 Athens, Greece.
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22
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23
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Shen H, Deng M, Zhang Y. Extension of CAVS coarse-grained model to phospholipid membranes: The importance of electrostatics. J Comput Chem 2017; 38:971-980. [DOI: 10.1002/jcc.24770] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2016] [Revised: 01/24/2017] [Accepted: 01/30/2017] [Indexed: 11/06/2022]
Affiliation(s)
- Hujun Shen
- Guizhou Provincial Key Laboratory of Computational Nano-Material Science; Guizhou Synergetic Innovation Center of Scientific Big Data for Advanced Manufacturing Technology, Guizhou Education University; No. 115, Gaoxin Road Guiyang Guizhou 550018 People's Republic of China
| | - Mingsen Deng
- Guizhou Provincial Key Laboratory of Computational Nano-Material Science; Guizhou Synergetic Innovation Center of Scientific Big Data for Advanced Manufacturing Technology, Guizhou Education University; No. 115, Gaoxin Road Guiyang Guizhou 550018 People's Republic of China
| | - Yachao Zhang
- Guizhou Provincial Key Laboratory of Computational Nano-Material Science; Guizhou Synergetic Innovation Center of Scientific Big Data for Advanced Manufacturing Technology, Guizhou Education University; No. 115, Gaoxin Road Guiyang Guizhou 550018 People's Republic of China
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24
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Chen LC, Xie NN, Deng SP. Sweetness-induced activation of membrane dipole potential in STC-1 taste cells. Food Chem 2016; 212:768-77. [DOI: 10.1016/j.foodchem.2016.06.016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2015] [Revised: 05/18/2016] [Accepted: 06/07/2016] [Indexed: 12/19/2022]
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25
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Pearlstein RA, Dickson CJ, Hornak V. Contributions of the membrane dipole potential to the function of voltage-gated cation channels and modulation by small molecule potentiators. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1859:177-194. [PMID: 27836643 DOI: 10.1016/j.bbamem.2016.11.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Revised: 10/28/2016] [Accepted: 11/06/2016] [Indexed: 01/27/2023]
Abstract
The membrane dipole potential (Ψd) constitutes one of three electrical potentials generated by cell membranes. Ψd arises from the unfavorable parallel alignment of phospholipid and water dipoles, and varies in magnitude both longitudinally and laterally across the bilayer according to membrane composition and phospholipid packing density. In this work, we propose that dynamic counter-balancing between Ψd and the transmembrane potential (ΔΨm) governs the conformational state transitions of voltage-gated ion channels. Ψd consists of 1) static outer, and dynamic inner leaflet components (Ψd(extra) and Ψd(intra), respectively); and 2) a transmembrane component (ΔΨd(inner-outer)), ariing from differences in intra- and extracellular leaflet composition. Ψd(intra), which transitions between high and low energy states (Ψd(intra, high) and Ψd(intra, low)) as a function of channel conformation, is transduced by the pore domain. ΔΨd(inner-outer) is transduced by the voltage-sensing (VS) domain in summation with ΔΨm. Potentiation of voltage-gated ion channels is of interest for the treatment of cardiac, neuronal, and other disorders arising from inherited/acquired ion channel dysfunction. Potentiators are widely believed to alter the rates and voltage-dependencies of channel gating transitions by binding to pockets in the membrane-facing and other regions of ion channel targets. Here, we propose that potentiators alter Ψd(intra) and/or Ψd(extra), thereby increasing or decreasing the energy barriers governing channel gating transitions. We used quantum mechanical and molecular dynamics (MD) simulations to predict the overall Ψd-modulating effects of a series of published positive hERG potentiators partitioned into model DOPC bilayers. Our findings suggest a strong correlation between the magnitude of Ψd-lowering and positive hERG potentiation across the series.
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Affiliation(s)
- Robert A Pearlstein
- Global Discovery Chemistry, Computer-Aided Drug Discovery, Novartis Institutes for BioMedical Research, 181 Mass Ave., Cambridge, MA 02139, USA.
| | - Callum J Dickson
- Global Discovery Chemistry, Computer-Aided Drug Discovery, Novartis Institutes for BioMedical Research, 181 Mass Ave., Cambridge, MA 02139, USA
| | - Viktor Hornak
- Global Discovery Chemistry, Computer-Aided Drug Discovery, Novartis Institutes for BioMedical Research, 181 Mass Ave., Cambridge, MA 02139, USA
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26
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Dipole-Potential-Mediated Effects on Ion Pump Kinetics. Biophys J 2016; 109:1513-20. [PMID: 26488640 DOI: 10.1016/j.bpj.2015.08.022] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Revised: 08/11/2015] [Accepted: 08/21/2015] [Indexed: 12/30/2022] Open
Abstract
The kinetics of conformational changes of P-type ATPases necessary for the occlusion or deocclusion of transported ions are known to be sensitive to the composition of the surrounding membrane, e.g., phospholipid content, mole percentage of cholesterol, and the presence of lipid-bound anions. Research has shown that many membrane components modify the dipole potential of the lipid head-group region. Based on the observation that occlusion/deocclusion reactions of ion pumps perturb the membrane surrounding the protein, a mechanism is suggested whereby dipole potential modifiers induce preferential stabilization or destabilization of occluded or nonoccluded states of the protein, leading to changes in the forward and backward rate constants for the transition. The mechanism relies on the assumption that conformational changes of the protein are associated with changes in its hydrophobic thickness that requires a change in local lipid packing density to allow hydrophobic matching with the membrane. The changes in lipid packing density cause changes in local lipid dipole potential that are responsible for the dependence of conformational kinetics on dipole potential modifiers. The proposed mechanism has the potential to explain effects of lipid composition on the kinetics of any membrane protein undergoing significant changes in its membrane cross-sectional area during its activity.
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27
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Ding W, Palaiokostas M, Wang W, Orsi M. Effects of Lipid Composition on Bilayer Membranes Quantified by All-Atom Molecular Dynamics. J Phys Chem B 2015; 119:15263-74. [PMID: 26560961 DOI: 10.1021/acs.jpcb.5b06604] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Biological bilayer membranes typically contain varying amounts of lamellar and nonlamellar lipids. Lamellar lipids, such as dioleoylphosphatidylcholine (DOPC), are defined by their tendency to form the lamellar phase, ubiquitous in biology. Nonlamellar lipids, such as dioleoylphosphatidylethanolamine (DOPE), prefer instead to form nonlamellar phases, which are mostly nonbiological. However, nonlamellar lipids mix with lamellar lipids in biomembrane structures that remain overall lamellar. Importantly, changes in the lamellar vs nonlamellar lipid composition are believed to affect membrane function and modulate membrane proteins. In this work, we employ atomistic molecular dynamics simulations to quantify how a range of bilayer properties are altered by variations in the lamellar vs nonlamellar lipid composition. Specifically, we simulate five DOPC/DOPE bilayers at mixing ratios of 1/0, 3/1, 1/1, 1/3, and 0/1. We examine properties including lipid area and bilayer thickness, as well as the transmembrane profiles of electron density, lateral pressure, electric field, and dipole potential. While the bilayer structure is only marginally altered by lipid composition changes, dramatic effects are observed for the lateral pressure, electric field, and dipole potential profiles. Possible implications for membrane function are discussed.
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Affiliation(s)
- Wei Ding
- School of Engineering & Materials Science, Queen Mary University of London , Mile End Road, London, E1 4NS, U.K
| | - Michail Palaiokostas
- School of Engineering & Materials Science, Queen Mary University of London , Mile End Road, London, E1 4NS, U.K
| | - Wen Wang
- School of Engineering & Materials Science, Queen Mary University of London , Mile End Road, London, E1 4NS, U.K
| | - Mario Orsi
- School of Engineering & Materials Science, Queen Mary University of London , Mile End Road, London, E1 4NS, U.K
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28
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Mares LJ, Garcia A, Rasmussen HH, Cornelius F, Mahmmoud YA, Berlin JR, Lev B, Allen TW, Clarke RJ. Identification of electric-field-dependent steps in the Na(+),K(+)-pump cycle. Biophys J 2015; 107:1352-63. [PMID: 25229143 DOI: 10.1016/j.bpj.2014.05.054] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Revised: 04/30/2014] [Accepted: 05/16/2014] [Indexed: 01/25/2023] Open
Abstract
The charge-transporting activity of the Na(+),K(+)-ATPase depends on its surrounding electric field. To isolate which steps of the enzyme's reaction cycle involve charge movement, we have investigated the response of the voltage-sensitive fluorescent probe RH421 to interaction of the protein with BTEA (benzyltriethylammonium), which binds from the extracellular medium to the Na(+),K(+)-ATPase's transport sites in competition with Na(+) and K(+), but is not occluded within the protein. We find that only the occludable ions Na(+), K(+), Rb(+), and Cs(+) cause a drop in RH421 fluorescence. We conclude that RH421 detects intramembrane electric field strength changes arising from charge transport associated with conformational changes occluding the transported ions within the protein, not the electric fields of the bound ions themselves. This appears at first to conflict with electrophysiological studies suggesting extracellular Na(+) or K(+) binding in a high field access channel is a major electrogenic reaction of the Na(+),K(+)-ATPase. All results can be explained consistently if ion occlusion involves local deformations in the lipid membrane surrounding the protein occurring simultaneously with conformational changes necessary for ion occlusion. The most likely origin of the RH421 fluorescence response is a change in membrane dipole potential caused by membrane deformation.
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Affiliation(s)
- Laura J Mares
- School of Chemistry, University of Sydney, Sydney, Australia
| | - Alvaro Garcia
- Department of Cardiology, Royal North Shore Hospital, Sydney, Australia; Kolling Institute, University of Sydney, Sydney, Australia
| | - Helge H Rasmussen
- Department of Cardiology, Royal North Shore Hospital, Sydney, Australia; Kolling Institute, University of Sydney, Sydney, Australia
| | | | | | - Joshua R Berlin
- Department of Pharmacology and Physiology, Rutgers University, Newark, New Jersey
| | - Bogdan Lev
- School of Applied Science and Health Innovations Research Institute, REMIT University, Melbourne, Australia
| | - Toby W Allen
- School of Applied Science and Health Innovations Research Institute, REMIT University, Melbourne, Australia
| | - Ronald J Clarke
- School of Chemistry, University of Sydney, Sydney, Australia.
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29
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Mihut AM, Dabkowska AP, Crassous JJ, Schurtenberger P, Nylander T. Tunable adsorption of soft colloids on model biomembranes. ACS NANO 2013; 7:10752-10763. [PMID: 24191704 DOI: 10.1021/nn403892f] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
A simple procedure is developed to probe in situ the association between lipid bilayers and colloidal particles. Here, a one-step method is applied to generate giant unilamellar 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) vesicles (GUVs) by application of an alternating electric field directly in the presence of thermoresponsive poly(N-isopropylacrylamide) (PNIPAM) microgels. We demonstrate that the soft PNIPAM microgel particles act as switchable stabilizers for lipid membranes. The change of the particle conformation from the swollen to the collapsed state enables the reversible control of the microgel adsorption as a function of temperature. At 20 °C, the swollen and hydrophilic soft microgel particles adsorb evenly and densely pack in 2D hexagonal arrays at the DOPC GUV surfaces. In contrast, at 40 °C, that is, above the volume phase transition temperature (TVPT = 32 °C) of the PNIPAM microgels, the collapsed and more hydrophobic particles partially desorb and self-organize into domains at the GUV/GUV interfaces. This study shows that thermoresponsive PNIPAM microgels can be used to increase and control the stability of lipid vesicles where the softness and deformability of these types of particles play a major role. The observed self-assembly, where the organization and position of the particles on the GUV surface can be controlled "on demand", opens new routes for the design of nanostructured materials.
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Affiliation(s)
- Adriana M Mihut
- Physical Chemistry, Department of Chemistry, Lund University , 22100 Lund, Sweden
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30
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Smiatek J, Harishchandra RK, Galla HJ, Heuer A. Low concentrated hydroxyectoine solutions in presence of DPPC lipid bilayers: A computer simulation study. Biophys Chem 2013; 180-181:102-9. [DOI: 10.1016/j.bpc.2013.07.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Revised: 07/05/2013] [Accepted: 07/05/2013] [Indexed: 02/05/2023]
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31
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Ostroumova OS, Efimova SS, Schagina LV. Changes of dipole potential of phospholipid membranes resulted from flavonoid adsorption. Biophysics (Nagoya-shi) 2013. [DOI: 10.1134/s0006350913030123] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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32
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Dal Molin M, Matile S. 3,4-Ethylenedioxythiophene in planarizable push-pull oligothiophenes. Org Biomol Chem 2013; 11:1952-7. [PMID: 23389656 DOI: 10.1039/c3ob27471c] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
We report design, synthesis and evaluation of push-pull quaterthiophene amphiphiles containing one 3,4-ethylenedioxythiophene (EDOT) and a single strong twist in the scaffold. Planarizable push-pull oligothiophene amphiphiles have been introduced recently as conceptually innovative fluorescent probes that sense the fluidity and the potential of lipid bilayer membranes. The "hyper-twisted" EDOT probes respond to planarization and restricted rotational freedom with a red shift and changes in vibrational finestructure in the excitation spectrum, respectively. In solution, comparably weak solvatochromism and significant thermochromism are found. Planarization and restricted rotational freedom afford exquisite sensitivity toward nature and fluidity of lipid bilayer membranes, including ratiometric detection of phase transitions. The sensing of membrane potentials is weakened by these unique properties but remains possible.
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Affiliation(s)
- Marta Dal Molin
- Department of Organic Chemistry, University of Geneva, Geneva, Switzerland
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Orsi M, Essex JW. Physical properties of mixed bilayers containing lamellar and nonlamellar lipids: insights from coarse-grain molecular dynamics simulations. Faraday Discuss 2013; 161:249-72; discussion 273-303. [DOI: 10.1039/c2fd20110k] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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Efimova SS, Ostroumova OS. Effect of dipole modifiers on the magnitude of the dipole potential of sterol-containing bilayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:9908-14. [PMID: 22702338 DOI: 10.1021/la301653s] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The effects of various subclasses of flavonoids, Rose Bengal, and different styrylpyridinium dyes on the magnitude of the dipole potential of membranes composed of pure phospholipids and sterol-containing bilayers were investigated. Changes in the steady-state membrane conductance induced by cation-ionophore complexes were measured to examine the changes in the dipole potential of lipid bilayers. The characteristic parameters of the Langmuir adsorption isotherm for different flavonoids and Rose Bengal and the slope of the linear dependence of the dipole potential change on the aqueous concentrations of RH dyes were estimated. Chalcones (phloretin and phloridzin) and flavonols (quercetin and myricetin) strictly decrease the dipole potential of phospholipid- and sterol-containing membranes; the unsaturation of the C-ring and the hydrophobicity of the molecule contribute to the ability of the flavonoid to reduce the bilayer dipole potential. Rose Bengal decreases the magnitude of the bilayer dipole potential to a similar extent, but its affinity for membrane lipids is higher; the effects of RH dyes, chalcones, and phloroglucinol are determined by sterol concentration and type.
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Affiliation(s)
- Svetlana S Efimova
- Institute of Cytology of the Russian Academy of Sciences, St. Petersburg 194064, Russia
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Reddy AS, Warshaviak DT, Chachisvilis M. Effect of membrane tension on the physical properties of DOPC lipid bilayer membrane. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2012; 1818:2271-81. [PMID: 22588133 DOI: 10.1016/j.bbamem.2012.05.006] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2012] [Revised: 05/03/2012] [Accepted: 05/07/2012] [Indexed: 01/15/2023]
Abstract
Molecular dynamics simulations of a dioleoylphosphocholine (DOPC) lipid bilayer were performed to explore its mechanosensitivity. Variations in the bilayer properties, such as area per lipid, volume, thickness, hydration depth (HD), hydration thickness (HT), lateral diffusion coefficient, and changes in lipid structural order were computed in the membrane tension range 0 to 15dyn/cm. We determined that an increase in membrane tension results in a decrease in the bilayer thickness and HD of ~5% and ~5.7% respectively, whereas area per lipid, volume, and HT/HD increased by 6.8%, 2.4%, and 5% respectively. The changes in lipid conformation and orientation were characterized using orientational (S(2)) and deuterium (S(CD)) order parameters. Upon increase of membrane tension both order parameters indicated an increase in lipid disorder by 10-20%, mostly in the tail end region of the hydrophobic chains. The effect of membrane tension on lipid lateral diffusion in the DOPC bilayer was analyzed on three different time scales corresponding to inertial motion, anomalous diffusion and normal diffusion. The results showed that lateral diffusion of lipid molecules is anomalous in nature due to the non-exponential distribution of waiting times. The anomalous and normal diffusion coefficients increased by 20% and 52% when the membrane tension changed from 0 to 15dyn/cm, respectively. In conclusion, our studies showed that membrane tension causes relatively significant changes in the area per lipid, volume, polarity, membrane thickness, and fluidity of the membrane suggesting multiple mechanisms by which mechanical perturbation of the membrane could trigger mechanosensitive response in cells.
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