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Ebert A, Dahley C. Can membrane permeability of zwitterionic compounds be predicted by the solubility-diffusion model? Eur J Pharm Sci 2024; 199:106819. [PMID: 38815700 DOI: 10.1016/j.ejps.2024.106819] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2024] [Revised: 04/23/2024] [Accepted: 05/27/2024] [Indexed: 06/01/2024]
Abstract
Zwitterions contain both positively and negatively charged functional groups, resulting in an overall net neutral charge. Nevertheless, the membrane permeability of the zwitterionic form of a compound is assumed to be much lower than the permeability of the uncharged neutral form. Although a significant proportion of pharmaceuticals are zwitterionic, it has not been clear so far whether their permeability is dominated by the permeation of the zwitterionic or the neutral form, since neutral fractions are often quite low as compared to the zwitterionic fraction. This complicates the in silico prediction of the permeability of zwitterionic compounds. In this work, we re-evaluated existing in vitro permeability data from literature measured with Caco-2/MDCK cell assays, using more strict exclusion criteria for effects like diffusion limitation by the aqueous boundary layers, paracellular transport, active transport and retention. Using this re-evaluated data set, we show that extracted intrinsic permeabilities of the neutral fraction are well predicted by the solubility-diffusion model (RMSE = 1.21; n = 18) if the permeability of the zwitterionic species is assumed negligible. Our work thus suggests that only the neutral species is relevant for the membrane permeability of zwitterionic compounds, and that membrane permeability of zwitterionic compounds is indeed predictable by the solubility-diffusion model.
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Affiliation(s)
- Andrea Ebert
- Department of Computational Biology & Chemistry, Helmholtz Centre for Environmental Research (UFZ), Permoserstraße 15, 04318 Leipzig, Germany.
| | - Carolin Dahley
- Department of Computational Biology & Chemistry, Helmholtz Centre for Environmental Research (UFZ), Permoserstraße 15, 04318 Leipzig, Germany
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2
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Dahley C, Böckmann T, Ebert A, Goss KU. Predicting the intrinsic membrane permeability of Caco-2/MDCK cells by the solubility-diffusion model. Eur J Pharm Sci 2024; 195:106720. [PMID: 38311258 DOI: 10.1016/j.ejps.2024.106720] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2023] [Revised: 01/17/2024] [Accepted: 02/01/2024] [Indexed: 02/09/2024]
Abstract
Membrane permeability is one of the main determinants for the absorption, distribution, metabolism and excretion of compounds and is therefore of crucial importance for successful drug development. Experiments with artificial phospholipid membranes have shown that the intrinsic membrane permeability (P0) of compounds is well-predicted by the solubility-diffusion model (SDM). However, using the solubility-diffusion model to predict the P0 of biological Caco-2 and MDCK cell membranes has proven unreliable so far. Recent publications revealed that many published P0 extracted from Caco-2 and MDCK experiments are incorrect. In this work, we therefore used a small self-generated set as well as a large revised set of experimental Caco-2 and MDCK data from literature to compare experimental and predicted P0. The P0 extracted from Caco-2 and MDCK experiments were systematically lower than the P0 predicted by the solubility-diffusion model. However, using the following correlation: log P0,Caco-2/MDCK = 0.84 log P0,SDM - 1.85, P0 of biological Caco-2 and MDCK cell membranes was well-predicted by the solubility-diffusion model.
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Affiliation(s)
- Carolin Dahley
- Department of Analytical Environmental Chemistry, Helmholtz Centre for Environmental Research (UFZ), Permoserstraße 15, Leipzig 04318, Germany
| | - Tim Böckmann
- Department of Analytical Environmental Chemistry, Helmholtz Centre for Environmental Research (UFZ), Permoserstraße 15, Leipzig 04318, Germany
| | - Andrea Ebert
- Department of Analytical Environmental Chemistry, Helmholtz Centre for Environmental Research (UFZ), Permoserstraße 15, Leipzig 04318, Germany.
| | - Kai-Uwe Goss
- Department of Analytical Environmental Chemistry, Helmholtz Centre for Environmental Research (UFZ), Permoserstraße 15, Leipzig 04318, Germany; Institute of Chemistry, University of Halle-Wittenberg, Kurt-Mothes-Straße 2, Halle 06120, Germany
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3
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Tivig I, Vallet L, Moisescu MG, Fernandes R, Andre FM, Mir LM, Savopol T. Early differentiation of mesenchymal stem cells is reflected in their dielectrophoretic behavior. Sci Rep 2024; 14:4330. [PMID: 38383752 PMCID: PMC10881469 DOI: 10.1038/s41598-024-54350-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Accepted: 02/12/2024] [Indexed: 02/23/2024] Open
Abstract
The therapeutic use of mesenchymal stem cells (MSCs) becomes more and more important due to their potential for cell replacement procedures as well as due to their immunomodulatory properties. However, protocols for MSCs differentiation can be lengthy and may result in incomplete or asynchronous differentiation. To ensure homogeneous populations for therapeutic purposes, it is crucial to develop protocols for separation of the different cell types after differentiation. In this article we show that, when MSCs start to differentiate towards adipogenic or osteogenic progenies, their dielectrophoretic behavior changes. The values of cell electric parameters which can be obtained by dielectrophoretic measurements (membrane permittivity, conductivity, and cytoplasm conductivity) change before the morphological features of differentiation become microscopically visible. We further demonstrate, by simulation, that these electric modifications make possible to separate cells in their early stages of differentiation by using the dielectrophoretic separation technique. A label free method which allows obtaining cultures of homogenously differentiated cells is thus offered.
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Grants
- PN-III-P2-2.1-PED-2021, grant no. 596PED/2022 Romanian Executive Agency for Higher Education, Research, Development, and Innovation Funding
- PN-III-P2-2.1-PED-2021, grant no. 596PED/2022 Romanian Executive Agency for Higher Education, Research, Development, and Innovation Funding
- PN-III-P2-2.1-PED-2021, grant no. 596PED/2022 Romanian Executive Agency for Higher Education, Research, Development, and Innovation Funding
- PN-III-P3-3.1-PM-RO-FR-2019, grant no. 11BM/2019 Romania-France cooperation program Hubert Curien-Brancusi
- PN-III-P3-3.1-PM-RO-FR-2019, grant no. 11BM/2019 Romania-France cooperation program Hubert Curien-Brancusi
- PN-III-P3-3.1-PM-RO-FR-2019, grant no. 11BM/2019 Romania-France cooperation program Hubert Curien-Brancusi
- PN-III-P3-3.1-PM-RO-FR-2019, grant no. 11BM/2019 Romania-France cooperation program Hubert Curien-Brancusi
- FET-OPEN H2020, grant no. 964562 Horizon 2020
- FET-OPEN H2020, grant no. 964562 Horizon 2020
- FET-OPEN H2020, grant no. 964562 Horizon 2020
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Affiliation(s)
- Ioan Tivig
- Biophysics and Cellular Biotechnology Department, Faculty of Medicine, Carol Davila University of Medicine and Pharmacy, 8 Eroii Sanitari Blvd., 050474, Bucharest, Romania
- Excellence Center for Research in Biophysics and Cellular Biotechnology, Carol Davila University of Medicine and Pharmacy, 050474, Bucharest, Romania
| | - Leslie Vallet
- METSY UMR 9018, Université Paris-Saclay, CNRS and Gustave Roussy, 94805, Villejuif, France
| | - Mihaela G Moisescu
- Biophysics and Cellular Biotechnology Department, Faculty of Medicine, Carol Davila University of Medicine and Pharmacy, 8 Eroii Sanitari Blvd., 050474, Bucharest, Romania.
- Excellence Center for Research in Biophysics and Cellular Biotechnology, Carol Davila University of Medicine and Pharmacy, 050474, Bucharest, Romania.
| | - Romain Fernandes
- METSY UMR 9018, Université Paris-Saclay, CNRS and Gustave Roussy, 94805, Villejuif, France
| | - Franck M Andre
- METSY UMR 9018, Université Paris-Saclay, CNRS and Gustave Roussy, 94805, Villejuif, France
| | - Lluis M Mir
- METSY UMR 9018, Université Paris-Saclay, CNRS and Gustave Roussy, 94805, Villejuif, France
| | - Tudor Savopol
- Biophysics and Cellular Biotechnology Department, Faculty of Medicine, Carol Davila University of Medicine and Pharmacy, 8 Eroii Sanitari Blvd., 050474, Bucharest, Romania
- Excellence Center for Research in Biophysics and Cellular Biotechnology, Carol Davila University of Medicine and Pharmacy, 050474, Bucharest, Romania
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4
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Dahley C, Garessus EDG, Ebert A, Goss KU. Impact of cholesterol and sphingomyelin on intrinsic membrane permeability. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2022; 1864:183953. [PMID: 35526600 DOI: 10.1016/j.bbamem.2022.183953] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Revised: 04/14/2022] [Accepted: 04/26/2022] [Indexed: 11/30/2022]
Abstract
Transwell experiments with Caco-2 or MDCK cells are the gold standard for determining the intestinal permeability of chemicals. The intrinsic membrane permeability (P0), that can be extracted from these experiments, might be comparable to P0 measured in black lipid membrane (BLM) experiments and P0 predicted by the solubility-diffusion model. Unfortunately, the overlap between experimental P0,Caco-2/MDCK and P0,BLM data is very small. So far, differences between both approaches have been attributed to the cholesterol and sphingomyelin content of cell membranes, but the database is too sparse to thoroughly test this theory. To create a diverse dataset, we measured P0,BLM of ten chemicals in BLM experiments using DPhPC and DPhPC/cholesterol/sphingomyelin membranes. The results were compared to predicted BLM data and experimental Caco-2/MDCK data obtained from literature. While P0,BLM of all chemicals was well predicted by the solubility-diffusion model, P0,Caco-2/MDCK was only predictable for rather hydrophilic compounds with logarithmic hexadecane/water partition coefficients below -0.5. The effect of cholesterol and sphingomyelin on P0,BLM was negligibly small.
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Affiliation(s)
- Carolin Dahley
- Department of Analytical Environmental Chemistry, Helmholtz Centre for Environmental Research (UFZ), Permoserstraße 15, 04318 Leipzig, Germany.
| | - Estella Dora Germaine Garessus
- Department of Analytical Environmental Chemistry, Helmholtz Centre for Environmental Research (UFZ), Permoserstraße 15, 04318 Leipzig, Germany
| | - Andrea Ebert
- Department of Analytical Environmental Chemistry, Helmholtz Centre for Environmental Research (UFZ), Permoserstraße 15, 04318 Leipzig, Germany.
| | - Kai-Uwe Goss
- Department of Analytical Environmental Chemistry, Helmholtz Centre for Environmental Research (UFZ), Permoserstraße 15, 04318 Leipzig, Germany; Institute of Chemistry, University of Halle-Wittenberg, Kurt-Mothes-Straße 2, 06120 Halle, Germany.
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5
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Wurl A, Ott M, Plato E, Meister A, Hamdi F, Kastritis PL, Blume A, Ferreira TM. Filling the Gap with Long n-Alkanes: Incorporation of C20 and C30 into Phospholipid Membranes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:8595-8606. [PMID: 35786894 DOI: 10.1021/acs.langmuir.2c00872] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Investigating how hydrophobic molecules mix with phospholipid bilayers and how they affect membrane properties is commonplace in biophysics. Despite this, a molecular-level empirical description of a membrane model as simple as a phospholipid bilayer with long linear hydrophobic chains incorporated is still missing. Here, we present an unprecedented molecular characterization of the incorporation of two long n-alkanes, n-eicosane (C20) and n-triacontane (C30) with 20 and 30 carbons, respectively, in phosphatidylcholine (PC) bilayers using a combination of experimental techniques (2H NMR, 31P NMR, 1H-13C dipolar recoupling solid-state NMR, X-ray scattering, and cryogenic electron microscopy) and atomistic molecular dynamics (MD) simulations. At low hydration, deuterated C20 and C30 yield 2H NMR spectra evidencing anisotropic-motion, which demonstrates their miscibility in PC membranes up to a critical alkane-to-acyl-chain volume fraction, ϕc. The acquired 2H NMR spectra of C20 and C30 have notably different lineshapes. At low alkane volume fractions below ϕc, CHARMM36 MD simulations predict such 2H NMR spectra qualitatively and thus enable an atomistic-level interpretation of the spectra. Above ϕc, the 2H NMR lineshapes become characteristic of motions in the intermediate-regime that, together with the MD simulation results, suggest the onset of immiscibility between the alkane molecules and the acyl chains. For all the systems investigated, the phospholipid molecular structure is unperturbed by the presence of the alkanes. However, at conditions of excess hydration and at surprisingly low alkane fractions below ϕc, a peak characteristic of isotropic motion is observed in both the 2H spectra of the alkanes and 31P spectra of the phospholipids, strongly indicating that the incorporation of the alkanes induces a reduction on the average radius of the lipid vesicles.
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Affiliation(s)
- Anika Wurl
- NMR Group - Institute of Physics, Martin Luther University Halle-Wittenberg, 06099 Halle (Saale), Germany
| | - Maria Ott
- Department of Biotechnology and Biochemistry, Martin Luther University Halle-Wittenberg, 06099 Halle, Saale, Germany
| | - Eric Plato
- NMR Group - Institute of Physics, Martin Luther University Halle-Wittenberg, 06099 Halle (Saale), Germany
| | - Annette Meister
- Department of Biotechnology and Biochemistry, Martin Luther University Halle-Wittenberg, 06099 Halle, Saale, Germany
| | - Farzad Hamdi
- Department of Biotechnology and Biochemistry, Martin Luther University Halle-Wittenberg, 06099 Halle, Saale, Germany
| | - Panagiotis L Kastritis
- Department of Biotechnology and Biochemistry, Martin Luther University Halle-Wittenberg, 06099 Halle, Saale, Germany
| | - Alfred Blume
- Insitute of Chemistry, Martin Luther University Halle-Wittenberg, 06099 Halle, Saale, Germany
| | - Tiago M Ferreira
- NMR Group - Institute of Physics, Martin Luther University Halle-Wittenberg, 06099 Halle (Saale), Germany
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6
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Asamoto DK, Kozachenko IA, López-Peña I, Kim JE. Bimolecular quenching of tryptophan fluorescence in a membrane protein: Evolution of local solvation and environment during folding into a bilayer. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2021; 260:119919. [PMID: 34004426 DOI: 10.1016/j.saa.2021.119919] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2021] [Revised: 04/29/2021] [Accepted: 05/02/2021] [Indexed: 06/12/2023]
Abstract
Fluorescence spectroscopy, including Stern-Volmer quenching, is a valuable tool for the study of protein dynamics. Changes in protein solvation during the folding reaction of a membrane protein, Outer membrane protein A (OmpA), into lipid bilayers was probed with bimolecular fluorescence quenching with acrylamide quencher. Six single-tryptophan OmpA mutants (W7, W15, W57, W102, W129, and W143) allowed for site-specific investigations at varying locations within the transmembrane β-barrel domain. A sphere-of-action quenching model that combines both static and dynamic components gave rise to Stern-Volmer quenching constants, KD, for OmpA denatured in 8.0 M urea, aggregated in 0.5 M urea, adsorbed onto small unilamellar vesicles (SUVs), and folded in SUVs (t = 6 hrs). The average KD values were KDdenatured(6.4M-1)>KDaggregated5.9M-1>KDadsorbed(1.9M-1)>KDfolded(0.6M-1). With knowledge of the fluorescence lifetimes in the absence of quencher, the bimolecular quenching constants, kq, were derived; the evolution of kq (and therefore KD)during the folding reaction into SUVs (t = 0 hr to t = 6 hrs) revealed desolvation timescales, τdesolv of 41-46 min (W7, W15, W57, W102), 27 min (W129), and 15 min (W143). The evolution of λmax during folding revealed fast and slow components, τenvironmentfast and τenvironmentslow of 7-13 min and 25-84 min, respectively, for all mutants. For the five lipid- facing mutants (W7, W15, W57, W129, and W143), the general trend was τenvironmentfast7-13min<τdesolv15-46min≤τenvironmentslow(25-84min). These results suggest that there is an initial fast step in which there is a large change in polarity to a hydrophobic environment, followed by a slower desolvation process during evolution within the hydrophobic environment. These results complement previous mechanisms of concerted folding and provide insights into site-specific changes in solvation during formation of native β-barrel structure.
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Affiliation(s)
- DeeAnn K Asamoto
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA, United States
| | - Ivan A Kozachenko
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA, United States
| | - Ignacio López-Peña
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA, United States
| | - Judy E Kim
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA, United States.
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7
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de Lange N, Kleijn JM, Leermakers FAM. Self-consistent field modeling of mesomorphic phase changes of monoolein and phospholipids in response to additives. Phys Chem Chem Phys 2021; 23:14093-14108. [PMID: 34159985 DOI: 10.1039/d1cp00697e] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Mapping the topological phase behaviour of lipids in aqueous solution is time consuming and finding the ideal lipid system for a desired application is often a matter of trial and error. Modelling techniques that can accurately predict the mesomorphic phase behaviour of lipid systems are therefore of paramount importance. Here, the self-consistent field theory of Scheutjens and Fleer (SF-SCF) in which a lattice refinement has been implemented, is used to scrutinize how various additives modify the self-assembled phase behaviour of monoolein (MO) and 1,2-dioleoyl-phosphatidylcholine (DOPC) lipids in water. The mesomorphic behaviour is inferred from trends in the mechanical properties of equilibrium lipid bilayers with increasing additive content. More specifically, we focus on the Helfrich parameters, that is, the mean and Gaussian bending rigidities (κ and [small kappa, Greek, macron], respectively) supplemented with the spontaneous curvature of the monolayer (Jm0). We use previously established interaction parameters that position the unperturbed DOPC system in the lamellar Lα phase ([small kappa, Greek, macron] < 0, κ > 0 and Jm0 ≈ 0). Similar interaction parameters position the MO system firmly in a bicontinuous cubic phase ([small kappa, Greek, macron] > 0). In line with experimental data, a mixture of MO and DOPC tends to be in one of these two phases, depending on the mixing ratio. Moreover we find good correlations between predicted trends and experimental data concerning the phase changes of MO in response to a wide range of additives. These correlations give credibility to the use of SF-SCF modelling as a valuable tool to quickly explore the mesomorphic phase space of (phospho)lipid bilayer systems including additives.
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Affiliation(s)
- N de Lange
- Physical Chemistry & Soft Matter, Wageningen University and Research, Stippeneng 4, 6708 WE, Wageningen, The Netherlands.
| | - J M Kleijn
- Physical Chemistry & Soft Matter, Wageningen University and Research, Stippeneng 4, 6708 WE, Wageningen, The Netherlands.
| | - F A M Leermakers
- Physical Chemistry & Soft Matter, Wageningen University and Research, Stippeneng 4, 6708 WE, Wageningen, The Netherlands.
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8
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Segan D, Stanley G, Messina P, Swiecicki J, Ngo K, Vivier V, Buriez O, Labbé E. Interaction of Redox Probes and Ferrocene‐labelled Peptides with Lipid Bilayers Observed at Lipid Bilayer‐Modified Electrodes. ChemElectroChem 2021. [DOI: 10.1002/celc.202100501] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Dejan Segan
- PASTEUR Département de chimie École Normale Supérieure PSL University Sorbonne Université CNRS 75005 Paris France
| | - George Stanley
- Laboratoire des biomolécules (LBM) Département de chimie École Normale supérieure PSL University Sorbonne Université CNRS 75005 Paris France
| | - Pierluca Messina
- PASTEUR Département de chimie École Normale Supérieure PSL University Sorbonne Université CNRS 75005 Paris France
| | - Jean‐Marie Swiecicki
- Laboratoire des biomolécules (LBM) Département de chimie École Normale supérieure PSL University Sorbonne Université CNRS 75005 Paris France
| | - Kieu Ngo
- Laboratoire Interfaces et Systèmes Électrochimiques (LISE) Sorbonne Université CNRS 75005 Paris France
| | - Vincent Vivier
- Laboratoire Interfaces et Systèmes Électrochimiques (LISE) Sorbonne Université CNRS 75005 Paris France
| | - Olivier Buriez
- PASTEUR Département de chimie École Normale Supérieure PSL University Sorbonne Université CNRS 75005 Paris France
| | - Eric Labbé
- PASTEUR Département de chimie École Normale Supérieure PSL University Sorbonne Université CNRS 75005 Paris France
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9
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Romer SH, Metzger S, Peraza K, Wright MC, Jobe DS, Song LS, Rich MM, Foy BD, Talmadge RJ, Voss AA. A mouse model of Huntington's disease shows altered ultrastructure of transverse tubules in skeletal muscle fibers. J Gen Physiol 2021; 153:211860. [PMID: 33683318 PMCID: PMC7931643 DOI: 10.1085/jgp.202012637] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Revised: 11/05/2020] [Accepted: 01/26/2021] [Indexed: 12/12/2022] Open
Abstract
Huntington’s disease (HD) is a fatal and progressive condition with severe debilitating motor defects and muscle weakness. Although classically recognized as a neurodegenerative disorder, there is increasing evidence of cell autonomous toxicity in skeletal muscle. We recently demonstrated that skeletal muscle fibers from the R6/2 model mouse of HD have a decrease in specific membrane capacitance, suggesting a loss of transverse tubule (t-tubule) membrane in R6/2 muscle. A previous report also indicated that Cav1.1 current was reduced in R6/2 skeletal muscle, suggesting defects in excitation–contraction (EC) coupling. Thus, we hypothesized that a loss and/or disruption of the skeletal muscle t-tubule system contributes to changes in EC coupling in R6/2 skeletal muscle. We used live-cell imaging with multiphoton confocal microscopy and transmission electron microscopy to assess the t-tubule architecture in late-stage R6/2 muscle and found no significant differences in the t-tubule system density, regularity, or integrity. However, electron microscopy images revealed that the cross-sectional area of t-tubules at the triad were 25% smaller in R6/2 compared with age-matched control skeletal muscle. Computer simulation revealed that the resulting decrease in the R6/2 t-tubule luminal conductance contributed to, but did not fully explain, the reduced R6/2 membrane capacitance. Analyses of bridging integrator-1 (Bin1), which plays a primary role in t-tubule formation, revealed decreased Bin1 protein levels and aberrant splicing of Bin1 mRNA in R6/2 muscle. Additionally, the distance between the t-tubule and sarcoplasmic reticulum was wider in R6/2 compared with control muscle, which was associated with a decrease in junctophilin 1 and 2 mRNA levels. Altogether, these findings can help explain dysregulated EC coupling and motor impairment in Huntington’s disease.
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Affiliation(s)
- Shannon H Romer
- Department of Biological Sciences, Wright State University, Dayton, OH.,Odyssey Systems, Environmental Health Effects Laboratory, Navy Medical Research Unit, Dayton, Wright-Patterson Air Force Base, Dayton, OH
| | - Sabrina Metzger
- Department of Neuroscience, Cell Biology, and Physiology, Wright State University, Dayton, OH
| | - Kristiana Peraza
- Department of Biological Sciences, California State Polytechnic University, Pomona, Pomona, CA
| | - Matthew C Wright
- Department of Biological Sciences, California State Polytechnic University, Pomona, Pomona, CA
| | - D Scott Jobe
- Department of Biological Sciences, Wright State University, Dayton, OH
| | - Long-Sheng Song
- Division of Cardiovascular Medicine, Department of Internal Medicine, Abboud Cardiovascular Research Center, University of Iowa Carver College of Medicine, Iowa City, IA
| | - Mark M Rich
- Department of Neuroscience, Cell Biology, and Physiology, Wright State University, Dayton, OH
| | - Brent D Foy
- Department of Physics, Wright State University, Dayton, OH
| | - Robert J Talmadge
- Department of Biological Sciences, California State Polytechnic University, Pomona, Pomona, CA
| | - Andrew A Voss
- Department of Biological Sciences, Wright State University, Dayton, OH
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10
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How We Came to Understand the "Tumultuous Chemical Heterogeneity" of the Lipid Bilayer Membrane. J Membr Biol 2020; 253:185-190. [PMID: 32488366 DOI: 10.1007/s00232-020-00126-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Accepted: 05/29/2020] [Indexed: 10/24/2022]
Abstract
The path to our modern understanding of the structure of the lipid bilayer membrane is a long one that can be traced from today perhaps as far back as Benjamin Franklin in the eighteenth century. Here, I provide a personal account of one of the important steps in that path, the description of the "Complete Structure" of a hydrated, fluid phase dioleoyl phosphatidylcholine bilayer by the joint refinement of neutron and X-ray diffraction data by Stephen White and his colleagues.
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11
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Xv L, Qian X, Wang Y, Yu C, Qin D, Zhang Y, Jin P, Du Q. Structural Modification of Nanomicelles through Phosphatidylcholine: The Enhanced Drug-Loading Capacity and Anticancer Activity of Celecoxib-Casein Nanoparticles for the Intravenous Delivery of Celecoxib. NANOMATERIALS 2020; 10:nano10030451. [PMID: 32131561 PMCID: PMC7153595 DOI: 10.3390/nano10030451] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Revised: 02/21/2020] [Accepted: 02/27/2020] [Indexed: 02/06/2023]
Abstract
This study aims to stabilize loaded celecoxib (CX) by modifying the structure of casein nanoparticles through phosphatidylcholine. The results show that Egg yolk phosphatidylcholine PC98T (PC) significantly increased the stability of CX-PC-casein nanoparticles (NPs) (192.6 nm) from 5 min (CX-β-casein-NPs) to 2.5 h at 37 °C. In addition, the resuspended freeze-dried NPs (202.4 nm) remained stable for 2.5 h. Scanning electron microscopy indicated that PC may block the micropore structures in nanoparticles by ultrasonic treatment and hence improve the physicochemical stability of CX-PC-casein-NPs. The stability of the NPs was positively correlated with their inhibiting ability for human malignant melanoma A375 cells. The structural modification of CX-PC-casein-NPs resulted in an increased intracellular uptake of CX by 2.4 times than that of the unmodified ones. The pharmacokinetic study showed that the Area Under Curve (AUC) of the CX-PC-casein-NPs was 2.9-fold higher in rats than that of the original casein nanoparticles. When CX-PC-casein-NPs were intravenously administrated to mice implanted with A375 tumors (CX dose = 16 mg/kg bodyweight), the tumor inhibition rate reached 56.2%, which was comparable to that of paclitaxel (57.3%) at a dose of 4 mg/kg bodyweight. Our results confirm that the structural modification of CX-PC-casein-NPs can effectively prolong the remaining time of specific drugs, and may provide a potential strategy for cancer treatment.
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Affiliation(s)
- Liuli Xv
- The Key Laboratory for Quality Improvement of Agricultural Products of Zhejiang Province, College of Agricultural and Food Sciences, Zhejiang A & F University, Hangzhou 311300, China; (L.X.); (X.Q.); (Y.W.); (D.Q.); (Y.Z.)
| | - Xinxin Qian
- The Key Laboratory for Quality Improvement of Agricultural Products of Zhejiang Province, College of Agricultural and Food Sciences, Zhejiang A & F University, Hangzhou 311300, China; (L.X.); (X.Q.); (Y.W.); (D.Q.); (Y.Z.)
| | - Yan Wang
- The Key Laboratory for Quality Improvement of Agricultural Products of Zhejiang Province, College of Agricultural and Food Sciences, Zhejiang A & F University, Hangzhou 311300, China; (L.X.); (X.Q.); (Y.W.); (D.Q.); (Y.Z.)
| | - Chenghuan Yu
- Experimental Animal Center of the Zhejiang Academy of Medical Sciences, Hangzhou 310013, China;
| | - Dingkui Qin
- The Key Laboratory for Quality Improvement of Agricultural Products of Zhejiang Province, College of Agricultural and Food Sciences, Zhejiang A & F University, Hangzhou 311300, China; (L.X.); (X.Q.); (Y.W.); (D.Q.); (Y.Z.)
| | - Yahui Zhang
- The Key Laboratory for Quality Improvement of Agricultural Products of Zhejiang Province, College of Agricultural and Food Sciences, Zhejiang A & F University, Hangzhou 311300, China; (L.X.); (X.Q.); (Y.W.); (D.Q.); (Y.Z.)
| | - Peng Jin
- The Key Laboratory for Quality Improvement of Agricultural Products of Zhejiang Province, College of Agricultural and Food Sciences, Zhejiang A & F University, Hangzhou 311300, China; (L.X.); (X.Q.); (Y.W.); (D.Q.); (Y.Z.)
- Correspondence: (P.J.); (Q.D.)
| | - Qizhen Du
- The Key Laboratory for Quality Improvement of Agricultural Products of Zhejiang Province, College of Agricultural and Food Sciences, Zhejiang A & F University, Hangzhou 311300, China; (L.X.); (X.Q.); (Y.W.); (D.Q.); (Y.Z.)
- Correspondence: (P.J.); (Q.D.)
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12
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Electrodeposition from Tannic acid-polyamine blends at pH = 5.0 is due to aggregate deposition and oxidation. Colloids Surf A Physicochem Eng Asp 2019. [DOI: 10.1016/j.colsurfa.2019.05.091] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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13
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Guha IF, Varanasi KK. Low-Voltage Surface Electrocoalescence Enabled by High-K Dielectrics and Surfactant Bilayers for Oil-Water Separation. ACS APPLIED MATERIALS & INTERFACES 2019; 11:34812-34818. [PMID: 31449381 DOI: 10.1021/acsami.9b01477] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Processes for separating oil-water mixtures are critical to operations in energy and water. However, existing separation methods pose efficiency limitations as well as environmental and safety challenges. Here, we present a low-voltage surface electrocoalescence approach that triggers coalescence of surfactant-stabilized emulsions by combining high-K dielectrics with surfactant bilayers. In this system, the high-K dielectric reduces the electrocoalescence voltage, while the surfactant bilayer functions as a self-healing, high capacitance film that prevents pinning of droplets on the dielectric surface. This high capacitance system maximizes the electric field between neighboring droplets, exerting high electrostatic pressure that overcomes the disjoining pressure between droplets, thereby enabling rapid electrocoalescence. We demonstrate electrocoalescence of surfactant-stabilized microscale droplets of saline water in oil using single volts. We expect our results may find application in the energy sector, wastewater treatment, and purification industries.
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Affiliation(s)
- Ingrid F Guha
- Electrical Engineering and Computer Science Department , Massachusetts Institute of Technology , 77 Massachusetts Avenue, 35-135 , Cambridge , Massachusetts 02139 , United States
| | - Kripa K Varanasi
- Department of Mechanical Engineering , Massachusetts Institute of Technology , 77 Massachusetts Avenue, 35-209 , Cambridge , Massachusetts 02139 , United States
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14
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De Pascalis R. Mechanically induced Helfrich-Hurault effect in a confined lamellar system with finite surface anchoring. Phys Rev E 2019; 100:012705. [PMID: 31499922 DOI: 10.1103/physreve.100.012705] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Indexed: 06/10/2023]
Abstract
Soft lamellar phases confined between two parallel plates and subject to a dilatative strain can become unstable exhibiting periodic deformations patterns of the layers. By a variational energy approach, a critical threshold for the imposed finite strain is derived in the case of weak anchoring conditions. The potential, associated to the system, includes a two-terms energy which accounts for the bending of the layers and the dilatation of the bulk as well as an anchoring potential. Classical results for strong anchoring at the walls are recovered. It is shown that weak anchoring conditions can lead to a lower critical threshold of the field, similarly as happens for the instability induced by a magnetic or an electric field normal to the layers. Nevertheless, in the limit of weak anchoring, the model reveals that this instability does not occur. Analytical formulas are provided which certainly encourage further experimental investigations.
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Affiliation(s)
- Riccardo De Pascalis
- Dipartimento di Matematica e Fisica "E. De Giorgi", Università del Salento, Via per Arnesano, 73100, Lecce, Italy
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15
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Abstract
This Review illustrates the evaluation of permeability of lipid membranes from molecular dynamics (MD) simulation primarily using water and oxygen as examples. Membrane entrance, translocation, and exit of these simple permeants (one hydrophilic and one hydrophobic) can be simulated by conventional MD, and permeabilities can be evaluated directly by Fick's First Law, transition rates, and a global Bayesian analysis of the inhomogeneous solubility-diffusion model. The assorted results, many of which are applicable to simulations of nonbiological membranes, highlight the limitations of the homogeneous solubility diffusion model; support the utility of inhomogeneous solubility diffusion and compartmental models; underscore the need for comparison with experiment for both simple solvent systems (such as water/hexadecane) and well-characterized membranes; and demonstrate the need for microsecond simulations for even simple permeants like water and oxygen. Undulations, subdiffusion, fractional viscosity dependence, periodic boundary conditions, and recent developments in the field are also discussed. Last, while enhanced sampling methods and increasingly sophisticated treatments of diffusion add substantially to the repertoire of simulation-based approaches, they do not address directly the critical need for force fields with polarizability and multipoles, and constant pH methods.
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Affiliation(s)
- Richard M Venable
- Laboratory of Computational Biology, National Lung, Heart, and Blood Institute , National Institutes of Health , Bethesda , Maryland 20892 , United States
| | - Andreas Krämer
- Laboratory of Computational Biology, National Lung, Heart, and Blood Institute , National Institutes of Health , Bethesda , Maryland 20892 , United States
| | - Richard W Pastor
- Laboratory of Computational Biology, National Lung, Heart, and Blood Institute , National Institutes of Health , Bethesda , Maryland 20892 , United States
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16
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Kwak SY, Lew TTS, Sweeney CJ, Koman VB, Wong MH, Bohmert-Tatarev K, Snell KD, Seo JS, Chua NH, Strano MS. Chloroplast-selective gene delivery and expression in planta using chitosan-complexed single-walled carbon nanotube carriers. NATURE NANOTECHNOLOGY 2019; 14:447-455. [PMID: 30804482 DOI: 10.1038/s41565-019-0375-4] [Citation(s) in RCA: 229] [Impact Index Per Article: 45.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Accepted: 01/14/2019] [Indexed: 05/19/2023]
Abstract
Plant genetic engineering is an important tool used in current efforts in crop improvement, pharmaceutical product biosynthesis and sustainable agriculture. However, conventional genetic engineering techniques target the nuclear genome, prompting concerns about the proliferation of foreign genes to weedy relatives. Chloroplast transformation does not have this limitation, since the plastid genome is maternally inherited in most plants, motivating the need for organelle-specific and selective nanocarriers. Here, we rationally designed chitosan-complexed single-walled carbon nanotubes, utilizing the lipid exchange envelope penetration mechanism. The single-walled carbon nanotubes selectively deliver plasmid DNA to chloroplasts of different plant species without external biolistic or chemical aid. We demonstrate chloroplast-targeted transgene delivery and transient expression in mature Eruca sativa, Nasturtium officinale, Nicotiana tabacum and Spinacia oleracea plants and in isolated Arabidopsis thaliana mesophyll protoplasts. This nanoparticle-mediated chloroplast transgene delivery tool provides practical advantages over current delivery techniques as a potential transformation method for mature plants to benefit plant bioengineering and biological studies.
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Affiliation(s)
- Seon-Yeong Kwak
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | | | - Connor J Sweeney
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Volodymyr B Koman
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Min Hao Wong
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | | | | | - Jun Sung Seo
- Temasek Life Sciences Laboratory, National University of Singapore, Singapore, Singapore
| | - Nam-Hai Chua
- Temasek Life Sciences Laboratory, National University of Singapore, Singapore, Singapore
| | - Michael S Strano
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA.
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17
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Vitkova V, Mitkova D, Antonova K, Popkirov G, Dimova R. Sucrose solutions alter the electric capacitance and dielectric permittivity of lipid bilayers. Colloids Surf A Physicochem Eng Asp 2018. [DOI: 10.1016/j.colsurfa.2018.05.011] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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18
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Lew TTS, Wong MH, Kwak SY, Sinclair R, Koman VB, Strano MS. Rational Design Principles for the Transport and Subcellular Distribution of Nanomaterials into Plant Protoplasts. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2018; 14:e1802086. [PMID: 30191658 DOI: 10.1002/smll.201802086] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Revised: 08/09/2018] [Indexed: 05/24/2023]
Abstract
The ability to control the subcellular localization of nanoparticles within living plants offers unique advantages for targeted biomolecule delivery and enables important applications in plant bioengineering. However, the mechanism of nanoparticle transport past plant biological membranes is poorly understood. Here, a mechanistic study of nanoparticle cellular uptake into plant protoplasts is presented. An experimentally validated mathematical model of lipid exchange envelope penetration mechanism for protoplasts, which predicts that the subcellular distribution of nanoparticles in plant cells is dictated by the particle size and the magnitude of the zeta potential, is advanced. The mechanism is completely generic, describing nanoparticles ranging from quantum dots, gold and silica nanoparticles, nanoceria, and single-walled carbon nanotubes (SWNTs). In addition, the use of imaging flow cytometry to investigate the influence of protoplasts' morphological characteristics on nanoparticle uptake efficiency is demonstrated. Using DNA-wrapped SWNTs as model nanoparticles, it is found that glycerolipids, the predominant lipids in chloroplast membranes, exhibit stronger lipid-nanoparticle interaction than phospholipids, the major constituent in protoplast membrane. This work can guide the rational design of nanoparticles for targeted delivery into specific compartments within plant cells without the use of chemical or mechanical aid, potentially enabling various plant engineering applications.
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Affiliation(s)
- Tedrick Thomas Salim Lew
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Min Hao Wong
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Seon-Yeong Kwak
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Rosalie Sinclair
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Volodymyr B Koman
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Michael S Strano
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
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19
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Johnson QR, Mostofian B, Fuente Gomez G, Smith JC, Cheng X. Effects of carotenoids on lipid bilayers. Phys Chem Chem Phys 2018; 20:3795-3804. [PMID: 29349456 DOI: 10.1039/c7cp07126d] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Carotenoids have been found to be important in improving the integrity of biomembranes in eukaryotes. However, the molecular details of how carotenoids modulate the physical properties of biomembranes are unknown. To this end, we have conducted a series of molecular dynamics simulations of different biologically-relevant membranes in the presence of carotenoids. The carotenoid effect on the membrane was found to be specific to the identity of the carotenoid and the composition of the membrane itself. Therefore, different classes of carotenoids produce a different effect on the membrane, and different membrane phases are affected differently by carotenoids. It is apparent from our data that carotenoids do trigger the bilayer to become thinner. The mechanism by which this occurs depends on two competing factors, the ability of the lipid tails of opposing monolayers to either (1) compress or (2) interdigitate as the bilayer condenses. Indeed, carotenoids directly influence the physical properties via these two mechanisms, thus compacting the bilayer. However, the degree to which these competing mechanisms are utilized depends on the bilayer phase and the carotenoid identity.
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Affiliation(s)
- Quentin R Johnson
- National Institute for Mathematical and Biological Synthesis, University of Tennessee, Knoxville, TN 37996, USA
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20
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Gaburjakova J, Gaburjakova M. Reconstitution of Ion Channels in Planar Lipid Bilayers: New Approaches. ADVANCES IN BIOMEMBRANES AND LIPID SELF-ASSEMBLY 2018. [DOI: 10.1016/bs.abl.2017.12.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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21
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Lebègue E, Smida H, Flinois T, Vié V, Lagrost C, Barrière F. An optimal surface concentration of pure cardiolipin deposited onto glassy carbon electrode promoting the direct electron transfer of cytochrome-c. J Electroanal Chem (Lausanne) 2018. [DOI: 10.1016/j.jelechem.2017.12.024] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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22
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Schulze Greiving VC, de Boer HL, Bomer JG, van den Berg A, Le Gac S. Integrated microfluidic biosensing platform for simultaneous confocal microscopy and electrophysiological measurements on bilayer lipid membranes and ion channels. Electrophoresis 2017; 39:496-503. [PMID: 29193178 DOI: 10.1002/elps.201700346] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Revised: 11/04/2017] [Accepted: 11/05/2017] [Indexed: 01/19/2023]
Abstract
Combining high-resolution imaging and electrophysiological recordings is key for various types of experimentation on lipid bilayers and ion channels. Here, we propose an integrated biosensing platform consisting of a microfluidic cartridge and a dedicated chip-holder to conduct such dual measurements on suspended lipid bilayers, in a user-friendly manner. To illustrate the potential of the integrated platform, we characterize lipid bilayers in terms of thickness and fluidity while simultaneously monitoring single ion channel currents. For that purpose, POPC lipid bilayers are supplemented with a fluorescently-tagged phospholipid (NBD-PE, 1% mol) for Fluorescence Recovery After Photobleaching (FRAP) measurements and a model ion channel (gramicidin, 1 nM). These combined measurements reveal that NBD-PE has no effect on the lipid bilayer thickness while gramicidin induces thinning of the membrane. Furthermore, the presence of gramicidin does not alter the lipid bilayer fluidity. Surprisingly, in lipid bilayers supplemented with both probes, a reduction in gramicidin open probability and lifetime is observed compared to lipid bilayers with gramicidin only, suggesting an influence of NBD-PE on the gramicidin ion function. Altogether, our proposed microfluidic biosensing platform in combination with the herein presented multi-parametric measurement scheme paves the way to explore the interdependent relationship between lipid bilayer properties and ion channel function.
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Affiliation(s)
- Verena C Schulze Greiving
- BIOS, Lab on a chip Group, MESA+ Institute for Nanotechnology, MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, Enschede, The Netherlands
| | - Hans L de Boer
- BIOS, Lab on a chip Group, MESA+ Institute for Nanotechnology, MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, Enschede, The Netherlands
| | - Johan G Bomer
- BIOS, Lab on a chip Group, MESA+ Institute for Nanotechnology, MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, Enschede, The Netherlands
| | - Albert van den Berg
- BIOS, Lab on a chip Group, MESA+ Institute for Nanotechnology, MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, Enschede, The Netherlands
| | - Séverine Le Gac
- BIOS, Lab on a chip Group, MESA+ Institute for Nanotechnology, MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, Enschede, The Netherlands
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23
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Herold KF, Andersen OS, Hemmings HC. Divergent effects of anesthetics on lipid bilayer properties and sodium channel function. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2017; 46:617-626. [PMID: 28695248 DOI: 10.1007/s00249-017-1239-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Revised: 06/27/2017] [Accepted: 07/01/2017] [Indexed: 02/07/2023]
Abstract
General anesthetics revolutionized medicine by allowing surgeons to perform more complex and much longer procedures. This widely used class of drugs is essential to patient care, yet their exact molecular mechanism(s) are incompletely understood. One early hypothesis over a century ago proposed that nonspecific interactions of anesthetics with the lipid bilayer lead to changes in neuronal function via effects on membrane properties. This model was supported by the Meyer-Overton correlation between anesthetic potency and lipid solubility and despite more recent evidence for specific protein targets, in particular ion-channels, lipid bilayer-mediated effects of anesthetics is still under debate. We therefore tested a wide range of chemically diverse general anesthetics on lipid bilayer properties using a sensitive and functional gramicidin-based assay. None of the tested anesthetics altered lipid bilayer properties at clinically relevant concentrations. Some anesthetics did affect the bilayer, though only at high supratherapeutic concentrations, which are unlikely relevant for clinical anesthesia. These results suggest that anesthetics directly interact with membrane proteins without altering lipid bilayer properties at clinically relevant concentrations. Voltage-gated Na+ channels are potential anesthetic targets and various isoforms are inhibited by a wide range of volatile anesthetics. They inhibit channel function by reducing peak Na+ current and shifting steady-state inactivation toward more hyperpolarized potentials. Recent advances in crystallography of prokaryotic Na+ channels, which are sensitive to volatile anesthetics, together with molecular dynamics simulations and electrophysiological studies will help identify potential anesthetic interaction sites within the channel protein itself.
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Affiliation(s)
- Karl F Herold
- Department of Anesthesiology, Weill Cornell Medicine, New York, NY, 10065, USA
| | - Olaf S Andersen
- Department of Physiology and Biophysics, Weill Cornell Medicine, New York, NY, 10065, USA
| | - Hugh C Hemmings
- Department of Anesthesiology, Weill Cornell Medicine, New York, NY, 10065, USA. .,Department of Pharmacology, Weill Cornell Medicine, New York, NY, 10065, USA.
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24
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Sizes of lipid domains: What do we know from artificial lipid membranes? What are the possible shared features with membrane rafts in cells? BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1859:789-802. [DOI: 10.1016/j.bbamem.2017.01.030] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2016] [Revised: 01/21/2017] [Accepted: 01/26/2017] [Indexed: 12/13/2022]
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25
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Alobeedallah H, Cornell B, Coster H. The Effect of Benzyl Alcohol on the Dielectric Structure of Lipid Bilayers. J Membr Biol 2016; 249:833-844. [PMID: 27803961 DOI: 10.1007/s00232-016-9934-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Accepted: 10/22/2016] [Indexed: 11/25/2022]
Abstract
Molecularly tethered lipid bilayer membranes were constructed on a commercially available chemically modified gold substrate. This is a new and promising product that has allowed the construction of very robust lipid bilayers. Very high resolution electrical impedance spectroscopy (EIS) was used to determine the dielectric structure of the lipid bilayers and associated interfaces. The EIS data were modelled in terms of the dielectric substructure using purpose developed software. The hydrophobic region, where the lipid tails are located, was revealed by the EIS in the frequency range of (1-100) Hz and its thickness was calculated from the capacitance of this region and found to be approximately 3-4 nm. The hydrophilic region, where the polar heads are located, was revealed at higher frequencies and its thickness was estimated to be approximately 1-2 nm. The effect of the local anaesthetic benzyl alcohol (BZA) on the tethered lipid bilayers was investigated. The effect of BZA on the membrane capacitance and conductance allowed the changes in the thickness of the polar head and hydrophobic tails regions to be determined. It was found that the addition of BZA caused a significant increase in the capacitance (corresponding to a decrease in the thickness) of the hydrophobic region and an increase in the membrane electrical conductance. The EIS allowed a distinction between a hydrophobic region in the centre of the bilayer and an outer hydrophobic region. Benzyl alcohol was found to have the largest effect on the outer, hydrophobic region, although the inner hydrophobic region was also consistently affected.
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Affiliation(s)
- Hadeel Alobeedallah
- School of Chemical and Biomolecular Engineering, The University of Sydney, Sydney, NSW, 2006, Australia.
| | - Bruce Cornell
- SDx Tethered Membranes Pty Ltd., Roseville, Sydney, NSW, 2069, Australia
| | - Hans Coster
- School of Chemical and Biomolecular Engineering, The University of Sydney, Sydney, NSW, 2006, Australia
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26
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John Gagliardi L, Shain DH. Electrostatic forces drive poleward chromosome motions at kinetochores. Cell Div 2016; 11:14. [PMID: 27807465 PMCID: PMC5086063 DOI: 10.1186/s13008-016-0026-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Accepted: 10/16/2016] [Indexed: 11/20/2022] Open
Abstract
BACKGROUND Recent experiments regarding Ndc80/Hec1 in force generation at kinetochores for chromosome motions have prompted speculation about possible models for interactions between positively charged molecules at kinetochores and negative charge at and near the plus ends of microtubules. DISCUSSION A clear picture of how kinetochores and centrosomes establish and maintain a dynamic coupling to microtubules for force generation during the complex motions of mitosis remains elusive. The current paradigm of molecular cell biology requires that specific molecules, or molecular geometries, for force generation be identified. However, it is possible to explain several different mitotic motions-including poleward force production at kinetochores-within a classical electrostatics approach in terms of experimentally known charge distributions, modeled as surface and volume bound charges interacting over nanometer distances. CONCLUSION We propose here that implicating Ndc80/Hec1 as a bound volume positive charge distribution in electrostatic generation of poleward force at kinetochores is most consistent with a wide range of experimental observations on mitotic motions, including polar production of poleward force and chromosome congression.
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Affiliation(s)
- L. John Gagliardi
- Departments of Physics and Biology, Rutgers The State University of New Jersey, Camden, NJ 08102 USA
| | - Daniel H. Shain
- Departments of Physics and Biology, Rutgers The State University of New Jersey, Camden, NJ 08102 USA
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27
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Interaction of Cecropin B with Zwitterionic and Negatively Charged Lipid Bilayers Immobilized at Gold Electrode Surface. Electrochim Acta 2016. [DOI: 10.1016/j.electacta.2016.04.080] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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28
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Pan L, Segrest JP. Computational studies of plasma lipoprotein lipids. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1858:2401-2420. [PMID: 26969087 DOI: 10.1016/j.bbamem.2016.03.010] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Revised: 03/03/2016] [Accepted: 03/04/2016] [Indexed: 12/27/2022]
Abstract
Plasma lipoproteins are macromolecular assemblies of proteins and lipids found in the blood. The lipid components of lipoproteins are amphipathic lipids such as phospholipids (PLs), and unesterified cholesterols (UCs) and hydrophobic lipids such as cholesteryl esters (CEs) and triglycerides (TGs). Since lipoproteins are soft matter supramolecular assemblies easily deformable by thermal fluctuations and they also exist in varying densities and protein/lipid components, a detailed understanding of their structure/function is experimentally difficult. Molecular dynamics (MD) simulation has emerged as a particularly promising way to explore the structure and dynamics of lipoproteins. The purpose of this review is to survey the current status of computational studies of the lipid components of the lipoproteins. Computational studies aim to explore three levels of complexity for the 3-dimensional structural dynamics of lipoproteins at various metabolic stages: (i) lipoprotein particles consist of protein with minimal lipid; (ii) lipoprotein particles consist of PL-rich discoidal bilayer-like lipid particles; (iii) mature circulating lipoprotein particles consist of CE-rich or TG-rich spheroidal lipid-droplet-like particles. Due to energy barriers involved in conversion between these species, other biomolecules also participate in lipoprotein biological assembly. For example: (i) lipid-poor apolipoprotein A-I (apoA-I) interacts with ATP-binding cassette transporter A1 (ABCA1) to produce nascent discoidal high density lipoprotein (dHDL) particles; (ii) lecithin-cholesterol acyltransferase (LCAT) mediates the conversion of UC to CE in dHDL, driving spheroidal HDL (sHDL) formation; (iii) transfer proteins, cholesterol ester transfer protein (CETP) and phospholipid transfer protein (PLTP), transfer both CE and TG and PL, respectively, between lipoprotein particles. Computational studies have the potential to explore different lipoprotein particles at each metabolic stage in atomistic detail. This review discusses the current status of computational methods including all-atom MD (AAMD), coarse-grain MD (CGMD), and MD-simulated annealing (MDSA) and their applications in lipoprotein structural dynamics and biological assemblies. Results from MD simulations are discussed and compared across studies in order to identify key findings, controversies, issues and future directions. This article is part of a Special Issue entitled: Biosimulations edited by Ilpo Vattulainen and Tomasz Róg.
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Affiliation(s)
- Lurong Pan
- Division of Gerontology, Geriatrics, & Palliative Care, School of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, United States
| | - Jere P Segrest
- Division of Gerontology, Geriatrics, & Palliative Care, School of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, United States.
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29
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Wong MH, Misra RP, Giraldo JP, Kwak SY, Son Y, Landry MP, Swan JW, Blankschtein D, Strano MS. Lipid Exchange Envelope Penetration (LEEP) of Nanoparticles for Plant Engineering: A Universal Localization Mechanism. NANO LETTERS 2016; 16:1161-72. [PMID: 26760228 DOI: 10.1021/acs.nanolett.5b04467] [Citation(s) in RCA: 121] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Nanoparticles offer clear advantages for both passive and active penetration into biologically important membranes. However, the uptake and localization mechanism of nanoparticles within living plants, plant cells, and organelles has yet to be elucidated.1 Here, we examine the subcellular uptake and kinetic trapping of a wide range of nanoparticles for the first time, using the plant chloroplast as a model system, but validated in vivo in living plants. Confocal visible and near-infrared fluorescent microscopy and single particle tracking of gold-cysteine-AF405 (GNP-Cys-AF405), streptavidin-quantum dot (SA-QD), dextran and poly(acrylic acid) nanoceria, and various polymer-wrapped single-walled carbon nanotubes (SWCNTs), including lipid-PEG-SWCNT, chitosan-SWCNT and 30-base (dAdT) sequence of ssDNA (AT)15 wrapped SWCNTs (hereafter referred to as ss(AT)15-SWCNT), are used to demonstrate that particle size and the magnitude, but not the sign, of the zeta potential are key in determining whether a particle is spontaneously and kinetically trapped within the organelle, despite the negative zeta potential of the envelope. We develop a mathematical model of this lipid exchange envelope and penetration (LEEP) mechanism, which agrees well with observations of this size and zeta potential dependence. The theory predicts a critical particle size below which the mechanism fails at all zeta potentials, explaining why nanoparticles are critical for this process. LEEP constitutes a powerful particulate transport and localization mechanism for nanoparticles within the plant system.
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Affiliation(s)
- Min Hao Wong
- Department of Chemical Engineering, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
| | - Rahul P Misra
- Department of Chemical Engineering, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
| | - Juan P Giraldo
- Department of Chemical Engineering, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
- Department of Botany and Plant Sciences, University of California , Riverside, California 92521, United States
| | - Seon-Yeong Kwak
- Department of Chemical Engineering, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
| | - Youngwoo Son
- Department of Chemical Engineering, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
| | - Markita P Landry
- Department of Chemical Engineering, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
- Department of Chemical and Biomolecular Engineering, University of California , Berkeley, California 94720
| | - James W Swan
- Department of Chemical Engineering, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
| | - Daniel Blankschtein
- Department of Chemical Engineering, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
| | - Michael S Strano
- Department of Chemical Engineering, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
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30
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Runas KA, Acharya SJ, Schmidt JJ, Malmstadt N. Addition of Cleaved Tail Fragments during Lipid Oxidation Stabilizes Membrane Permeability Behavior. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:779-786. [PMID: 26704691 DOI: 10.1021/acs.langmuir.5b02980] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Lipid oxidation has been linked to plasma membrane damage leading to cell death. In previous work, we examined the effect of oxidation on bilayer permeability by replacing defined amounts of an unsaturated lipid species with the corresponding phospholipid product that would result from oxidative tail scission of that species. This study adds the cleaved tail fragment, better mimicking the chemical results of oxidation. Permeability of PEG12-NBD, a small, uncharged molecule, was measured for vesicles with oxidation concentration corresponding to between 0 and 18 mol % of total lipid content. Permeability was measured using a microfluidic trap to capture the vesicles and spinning disk confocal microscopy (SDCM) to measure the transport of fluorescent PEG12-NBD at the equatorial plane. The thicknesses of lipid bilayers containing oxidized species were estimated by measuring capacitance of a black lipid membrane while simultaneously measuring bilayer area. We found that relative to chemically modeled oxidized bilayers without tail fragments, bilayers containing cleaved tail groups were less permeable for the same degree of oxidation. Curiously, membrane capacitance measurements indicated that the addition of tail fragments to chemically modeled oxidized bilayers also thinned these bilayers relative to samples with no tail fragments; in other words, the more permeable membranes were thicker. Above 12.5% chemically modeled oxidation, compositions both with and without the cleaved tail groups showed pore formation. This work highlights the complexity of the relationship between chemically modeled lipid bilayer oxidation and cell membrane properties.
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Affiliation(s)
- Kristina A Runas
- Mork Family Department of Chemical Engineering and Materials Science University of Southern California , Los Angeles, California 90089, United States
| | - Shiv J Acharya
- Department of Bioengineering University of California, Los Angeles , Los Angeles, California 90095, United States
| | - Jacob J Schmidt
- Department of Bioengineering University of California, Los Angeles , Los Angeles, California 90095, United States
| | - Noah Malmstadt
- Mork Family Department of Chemical Engineering and Materials Science University of Southern California , Los Angeles, California 90089, United States
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31
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Antonova K, Vitkova V, Meyer C. Membrane tubulation from giant lipid vesicles in alternating electric fields. Phys Rev E 2016; 93:012413. [PMID: 26871107 DOI: 10.1103/physreve.93.012413] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Indexed: 06/05/2023]
Abstract
We report on the formation of tubular membrane protrusions from giant unilamellar vesicles in alternating electric fields. The construction of the experimental chamber permitted the application of external AC fields with strength of dozens of V/mm and kHz frequency during relatively long time periods (several minutes). Besides the vesicle electrodeformation from quasispherical to prolate ellipsoidal shape, the formation of long tubular membrane protrusions with length of up to several vesicle diameters, arising from the vesicular surface in the field direction, was registered and analyzed. The threshold electric field at which the electro-induced protrusions appeared was lower than the field strengths inducing membrane electroporation.
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Affiliation(s)
- K Antonova
- Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tzarigradsko chaussee, Sofia 1784, Bulgaria
| | - V Vitkova
- Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tzarigradsko chaussee, Sofia 1784, Bulgaria
| | - C Meyer
- Laboratoire de Physique des Systèmes Complexes, Université de Picardie Jules Verne, 33 rue Saint Leu, 80039 Amiens, France
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32
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Posson DJ, Rusinova R, Andersen OS, Nimigean CM. Calcium ions open a selectivity filter gate during activation of the MthK potassium channel. Nat Commun 2015; 6:8342. [PMID: 26395539 PMCID: PMC4580985 DOI: 10.1038/ncomms9342] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2015] [Accepted: 08/11/2015] [Indexed: 12/25/2022] Open
Abstract
Ion channel opening and closing are fundamental to cellular signalling and homeostasis. Gates that control K+ channel activity were found both at an intracellular pore constriction and within the selectivity filter near the extracellular side but the specific location of the gate that opens Ca2+-activated K+ channels has remained elusive. Using the Methanobacterium thermoautotrophicum homologue (MthK) and a stopped-flow fluorometric assay for fast channel activation, we show that intracellular quaternary ammonium blockers bind to closed MthK channels. Since the blockers are known to bind inside a central channel cavity, past the intracellular entryway, the gate must be within the selectivity filter. Furthermore, the blockers access the closed channel slower than the open channel, suggesting that the intracellular entryway narrows upon pore closure, without preventing access of either the blockers or the smaller K+. Thus, Ca2+-dependent gating in MthK occurs at the selectivity filter with coupled movement of the intracellular helices. Ion channels open and close to allow the regulated passage of ions through the membrane. Here the authors use selective ion channel blockers to analyse this regulation in a potassium channel and show that the gate is in the selectivity filter, past the entrance to the channel.
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Affiliation(s)
- David J Posson
- Department of Anesthesiology, Weill Cornell Medical College, 1300 York Avenue, New York, New York 10021, USA.,Department of Physiology and Biophysics, Weill Cornell Medical College, 1300 York Avenue, New York, New York 10021, USA
| | - Radda Rusinova
- Department of Anesthesiology, Weill Cornell Medical College, 1300 York Avenue, New York, New York 10021, USA.,Department of Physiology and Biophysics, Weill Cornell Medical College, 1300 York Avenue, New York, New York 10021, USA
| | - Olaf S Andersen
- Department of Physiology and Biophysics, Weill Cornell Medical College, 1300 York Avenue, New York, New York 10021, USA
| | - Crina M Nimigean
- Department of Anesthesiology, Weill Cornell Medical College, 1300 York Avenue, New York, New York 10021, USA.,Department of Physiology and Biophysics, Weill Cornell Medical College, 1300 York Avenue, New York, New York 10021, USA.,Department of Biochemistry, Weill Cornell Medical College, 1300 York Avenue, New York, New York 10021, USA
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33
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Lomora M, Dinu IA, Itel F, Rigo S, Spulber M, Palivan CG. Does Membrane Thickness Affect the Transport of Selective Ions Mediated by Ionophores in Synthetic Membranes? Macromol Rapid Commun 2015; 36:1929-1934. [DOI: 10.1002/marc.201500289] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2015] [Revised: 07/30/2015] [Indexed: 11/07/2022]
Affiliation(s)
- Mihai Lomora
- Department of Chemistry; University of Basel; Klingelbergstrasse 80 4056 Basel Switzerland
| | - Ionel Adrian Dinu
- Department of Chemistry; University of Basel; Klingelbergstrasse 80 4056 Basel Switzerland
| | - Fabian Itel
- Department of Chemistry; University of Basel; Klingelbergstrasse 80 4056 Basel Switzerland
| | - Serena Rigo
- Department of Chemistry; University of Basel; Klingelbergstrasse 80 4056 Basel Switzerland
| | - Mariana Spulber
- Department of Chemistry; University of Basel; Klingelbergstrasse 80 4056 Basel Switzerland
| | - Cornelia G. Palivan
- Department of Chemistry; University of Basel; Klingelbergstrasse 80 4056 Basel Switzerland
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34
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Atomic Force Microscopy and Electrochemical Studies of Melittin Action on Lipid Bilayers Supported on Gold Electrodes. Electrochim Acta 2015. [DOI: 10.1016/j.electacta.2014.10.039] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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35
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Gagliardi LJ, Shain DH. Polar electrostatic forces drive poleward chromosome motions. Cell Div 2014; 9:5. [PMID: 25717343 PMCID: PMC4339643 DOI: 10.1186/s13008-014-0005-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2014] [Accepted: 12/02/2014] [Indexed: 11/16/2022] Open
Abstract
Recent experiments revealing nanoscale electrostatic force generation at kinetochores for chromosome motions have prompted models for interactions between positively charged molecules in kinetochores and negative charge at and near the plus ends of microtubules. A clear picture of how kinetochores and centrosomes establish and maintain a dynamic coupling to microtubules for force generation during the complex motions of mitosis remains elusive. The molecular cell biology paradigm requires that specific molecules, or molecular geometries, for polar force generation be identified. While progress has been made regarding explanations of kinetochore-based chromosome motility, molecular machinery for chromosome poleward movements at centrosomes has yet to be identified. The present work concerns polar generation of poleward force in terms of experimentally known electric charge distributions at microtubule minus ends and centrosomes interacting over nanometer distances.
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Affiliation(s)
- Lucian John Gagliardi
- Department of Physics, Rutgers The State University of New Jersey, Camden, NJ 08102 USA
| | - Daniel H Shain
- Department of Biology, Rutgers The State University of New Jersey, Camden, NJ 08102 USA
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36
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Gerelli Y, de Ghellinck A, Jouhet J, Laux V, Haertlein M, Fragneto G. Multi-lamellar organization of fully deuterated lipid extracts of yeast membranes. ACTA ACUST UNITED AC 2014; 70:3167-76. [PMID: 25478835 DOI: 10.1107/s1399004714022913] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Accepted: 10/18/2014] [Indexed: 05/28/2023]
Abstract
Neutron scattering studies on mimetic biomembranes are currently limited by the low availability of deuterated unsaturated lipid species. In the present work, results from the first neutron diffraction experiments on fully deuterated lipid extracts from the yeast Pichia pastoris are presented. The structural features of these fully deuterated lipid stacks are compared with those of their hydrogenous analogues and with other similar synthetic systems. The influence of temperature and humidity on the samples has been investigated by means of small momentum-transfer neutron diffraction. All of the lipid extracts investigated self-assemble into multi-lamellar stacks having different structural periodicities; the stacking distances are affected by temperature and humidity without altering the basic underlying arrangement. At high relative humidity the deuterated and hydrogenous samples are similar in their multi-lamellar arrangement, being characterized by two main periodicities of ∼75 and ∼110 Å reflecting the presence of a large number of polar phospholipid molecules. Larger differences are found at lower relative humidity, where hydrogenous lipids are characterized by a larger single lamellar structure than that observed in the deuterated samples. In both cases the heterogeneity in composition is reflected in a wide structural complexity. The different behaviour upon dehydration can be related to compositional differences in the molecular composition of the two samples, which is attributed to metabolic effects related to the use of perdeuterated growth media.
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Affiliation(s)
- Yuri Gerelli
- Institut Laue-Langevin, 71 Avenue des Martyrs, 38000 Grenoble, France
| | | | - Juliette Jouhet
- Laboratoire de Physiologie Cellulaire and Végétale (LPCV), CNRS (UMR5168)/Université Grenoble Alpes/INRA (USC1359)/CEA Grenoble, Institut de Recherches en Technologies et Sciences pour le Vivant (iRTSV), 17 Rue des Martyrs, 38054 Grenoble CEDEX 9, France
| | - Valérie Laux
- Institut Laue-Langevin, 71 Avenue des Martyrs, 38000 Grenoble, France
| | - Michael Haertlein
- Institut Laue-Langevin, 71 Avenue des Martyrs, 38000 Grenoble, France
| | - Giovanna Fragneto
- Institut Laue-Langevin, 71 Avenue des Martyrs, 38000 Grenoble, France
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37
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Kalsi S, Powl AM, Wallace BA, Morgan H, de Planque MRR. Shaped apertures in photoresist films enhance the lifetime and mechanical stability of suspended lipid bilayers. Biophys J 2014; 106:1650-9. [PMID: 24739164 PMCID: PMC4008792 DOI: 10.1016/j.bpj.2014.02.033] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2013] [Revised: 02/12/2014] [Accepted: 02/26/2014] [Indexed: 11/22/2022] Open
Abstract
Planar lipid bilayers suspended in apertures provide a controlled environment for ion channel studies. However, short lifetimes and poor mechanical stability of suspended bilayers limit the experimental throughput of bilayer electrophysiology experiments. Although bilayers are more stable in smaller apertures, ion channel incorporation through vesicle fusion with the suspended bilayer becomes increasingly difficult. In an alternative bilayer stabilization approach, we have developed shaped apertures in SU8 photoresist that have tapered sidewalls and a minimum diameter between 60 and 100 μm. Bilayers formed at the thin tip of these shaped apertures, either with the painting or the folding method, display drastically increased lifetimes, typically >20 h, and mechanical stability, being able to withstand extensive perturbation of the buffer solution. Single-channel electrical recordings of the peptide alamethicin and of the proteoliposome-delivered potassium channel KcsA demonstrate channel conductance with low noise, made possible by the small capacitance of the 50 μm thick SU8 septum, which is only thinned around the aperture, and unimpeded proteoliposome fusion, enabled by the large aperture diameter. We anticipate that these shaped apertures with micrometer edge thickness can substantially enhance the throughput of channel characterization by bilayer lipid membrane electrophysiology, especially in combination with automated parallel bilayer platforms.
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Affiliation(s)
- Sumit Kalsi
- Electronics and Computer Science, University of Southampton, Southampton, United Kingdom; Institute for Life Sciences, University of Southampton, Southampton, United Kingdom.
| | - Andrew M Powl
- Institute of Structural and Molecular Biology, Birkbeck College, University of London, London, United Kingdom
| | - B A Wallace
- Institute of Structural and Molecular Biology, Birkbeck College, University of London, London, United Kingdom
| | - Hywel Morgan
- Electronics and Computer Science, University of Southampton, Southampton, United Kingdom; Institute for Life Sciences, University of Southampton, Southampton, United Kingdom
| | - Maurits R R de Planque
- Electronics and Computer Science, University of Southampton, Southampton, United Kingdom; Institute for Life Sciences, University of Southampton, Southampton, United Kingdom.
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38
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Messina P, Lemaître F, Huet F, Ngo KA, Vivier V, Labbé E, Buriez O, Amatore C. Monitoring and Quantifying the Passive Transport of Molecules Through Patch-Clamp Suspended Real and Model Cell Membranes. Angew Chem Int Ed Engl 2014. [DOI: 10.1002/ange.201308990] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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39
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Messina P, Lemaître F, Huet F, Ngo KA, Vivier V, Labbé E, Buriez O, Amatore C. Monitoring and quantifying the passive transport of molecules through patch-clamp suspended real and model cell membranes. Angew Chem Int Ed Engl 2014; 53:3192-6. [PMID: 24519879 DOI: 10.1002/anie.201308990] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Revised: 12/06/2013] [Indexed: 11/11/2022]
Abstract
Transport of active molecules across biological membranes is a central issue for the success of many pharmaceutical strategies. Herein, we combine the patch-clamp principle with amperometric detection for monitoring fluxes of redox-tagged molecular species across a suspended membrane patched from a macrophage. Solvent- and protein-free lipid bilayers (DPhPC, DOPC, DOPG) patched from single-wall GUV have been thoroughly investigated and the corresponding fluxes measurements quantified. The quality of the patches and their proper sealing were successfully characterized by electrochemical impedance spectroscopy. This procedure appears versatile and perfectly adequate to allow the investigation of transport and quantification of the transport properties through direct measurement of the coefficients of partition and diffusion of the compound in the membrane, thus offering insight on such important biological and pharmacological issues.
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Affiliation(s)
- Pierluca Messina
- Ecole Normale Supérieure, Département de Chimie, UMR CNRS-ENS-UPMC 8640 "PASTEUR", 24 rue Lhomond, 75231 Paris cedex 05 (France)
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40
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Dynamic response of model lipid membranes to ultrasonic radiation force. PLoS One 2013; 8:e77115. [PMID: 24194863 PMCID: PMC3806737 DOI: 10.1371/journal.pone.0077115] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2013] [Accepted: 08/29/2013] [Indexed: 12/14/2022] Open
Abstract
Low-intensity ultrasound can modulate action potential firing in neurons in vitro and in vivo. It has been suggested that this effect is mediated by mechanical interactions of ultrasound with neural cell membranes. We investigated whether these proposed interactions could be reproduced for further study in a synthetic lipid bilayer system. We measured the response of protein-free model membranes to low-intensity ultrasound using electrophysiology and laser Doppler vibrometry. We find that ultrasonic radiation force causes oscillation and displacement of lipid membranes, resulting in small (<1%) changes in membrane area and capacitance. Under voltage-clamp, the changes in capacitance manifest as capacitive currents with an exponentially decaying sinusoidal time course. The membrane oscillation can be modeled as a fluid dynamic response to a step change in pressure caused by ultrasonic radiation force, which disrupts the balance of forces between bilayer tension and hydrostatic pressure. We also investigated the origin of the radiation force acting on the bilayer. Part of the radiation force results from the reflection of the ultrasound from the solution/air interface above the bilayer (an effect that is specific to our experimental configuration) but part appears to reflect a direct interaction of ultrasound with the bilayer, related to either acoustic streaming or scattering of sound by the bilayer. Based on these results, we conclude that synthetic lipid bilayers can be used to study the effects of ultrasound on cell membranes and membrane proteins.
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41
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Stacey MW, Sabuncu AC, Beskok A. Dielectric characterization of costal cartilage chondrocytes. Biochim Biophys Acta Gen Subj 2013; 1840:146-52. [PMID: 24016606 DOI: 10.1016/j.bbagen.2013.08.031] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2013] [Revised: 07/24/2013] [Accepted: 08/29/2013] [Indexed: 11/18/2022]
Abstract
BACKGROUND Chondrocytes respond to biomechanical and bioelectrochemical stimuli by secreting appropriate extracellular matrix proteins that enable the tissue to withstand the large forces it experiences. Although biomechanical aspects of cartilage are well described, little is known of the bioelectrochemical responses. The focus of this study is to identify bioelectrical characteristics of human costal cartilage cells using dielectric spectroscopy. METHODS Dielectric spectroscopy allows non-invasive probing of biological cells. An in house computer program is developed to extract dielectric properties of human costal cartilage cells from raw cell suspension impedance data measured by a microfluidic device. The dielectric properties of chondrocytes are compared with other cell types in order to comparatively assess the electrical nature of chondrocytes. RESULTS The results suggest that electrical cell membrane characteristics of chondrocyte cells are close to cardiomyoblast cells, cells known to possess an array of active ion channels. The blocking effect of the non-specific ion channel blocker gadolinium is tested on chondrocytes with a significant reduction in both membrane capacitance and conductance. CONCLUSIONS We have utilized a microfluidic chamber to mimic biomechanical events through changes in bioelectrochemistry and described the dielectric properties of chondrocytes to be closer to cells derived from electrically excitably tissues. GENERAL SIGNIFICANCE The study describes dielectric characterization of human costal chondrocyte cells using physical tools, where results and methodology can be used to identify potential anomalies in bioelectrochemical responses that may lead to cartilage disorders.
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Affiliation(s)
- Michael W Stacey
- Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, VA 23508, USA
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42
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Minetti G, Egée S, Mörsdorf D, Steffen P, Makhro A, Achilli C, Ciana A, Wang J, Bouyer G, Bernhardt I, Wagner C, Thomas S, Bogdanova A, Kaestner L. Red cell investigations: Art and artefacts. Blood Rev 2013; 27:91-101. [DOI: 10.1016/j.blre.2013.02.002] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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43
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Meech R. A contribution to the history of the proton channel. WILEY INTERDISCIPLINARY REVIEWS. MEMBRANE TRANSPORT AND SIGNALING 2012; 1:533-557. [PMID: 23365805 PMCID: PMC3556693 DOI: 10.1002/wmts.59] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
The low numbers of hydrogen ions in physiological solutions encouraged the assumption that H(+) currents flowing through conductive pathways would be so small as to be unmeasurable even if theoretically possible. Evidence for an H(+)-based action potential in the luminescent dinoflagellate Noctiluca and for an H(+)-conducting channel created by the secretions of the bacterium Bacillus brevis, did little to alter this perception. The clear demonstration of H(+) conduction in molluscan neurons might have provided the breakthrough but the new pathway was without an easily demonstrable function, and escaped general attention. Indeed the extreme measures that must be taken to successfully isolate H(+) currents meant that it was some years before proton channels were identified in mammalian cells. However, with the general availability of patch-clamp techniques and evidence for an important role in mammalian neutrophils, the stage was set for a series of structure/function studies with the potential to make the proton channel the best understood channel of all. In addition, widespread genomic searches have established that proton channels play important roles in processes ranging from fertilization of the human ovum to the progression of breast cancer. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
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Affiliation(s)
- Robert Meech
- School of Physiology & Pharmacology, University of Bristol, Medical Sciences Building, University WalkBristol BS8 1TD, UK
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44
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Campos R, Kataky R. Electron Transport in Supported and Tethered Lipid Bilayers Modified with Bioelectroactive Molecules. J Phys Chem B 2012; 116:3909-17. [DOI: 10.1021/jp209772u] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Rui Campos
- Department of Chemistry, Durham University, South Road, Durham, DH1 3LE, United Kingdom
| | - Ritu Kataky
- Department of Chemistry, Durham University, South Road, Durham, DH1 3LE, United Kingdom
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45
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Sharp Ca²⁺ nanodomains beneath the ribbon promote highly synchronous multivesicular release at hair cell synapses. J Neurosci 2012; 31:16637-50. [PMID: 22090491 DOI: 10.1523/jneurosci.1866-11.2011] [Citation(s) in RCA: 125] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Hair cell ribbon synapses exhibit several distinguishing features. Structurally, a dense body, or ribbon, is anchored to the presynaptic membrane and tethers synaptic vesicles; functionally, neurotransmitter release is dominated by large EPSC events produced by seemingly synchronous multivesicular release. However, the specific role of the synaptic ribbon in promoting this form of release remains elusive. Using complete ultrastructural reconstructions and capacitance measurements of bullfrog amphibian papilla hair cells dialyzed with high concentrations of a slow Ca²⁺ buffer (10 mM EGTA), we found that the number of synaptic vesicles at the base of the ribbon correlated closely to those vesicles that released most rapidly and efficiently, while the rest of the ribbon-tethered vesicles correlated to a second, slower pool of vesicles. Combined with the persistence of multivesicular release in extreme Ca²⁺ buffering conditions (10 mM BAPTA), our data argue against the Ca²⁺-dependent compound fusion of ribbon-tethered vesicles at hair cell synapses. Moreover, during hair cell depolarization, our results suggest that elevated Ca²⁺ levels enhance vesicle pool replenishment rates. Finally, using Ca²⁺ diffusion simulations, we propose that the ribbon and its vesicles define a small cytoplasmic volume where Ca²⁺ buffer is saturated, despite 10 mM BAPTA conditions. This local buffer saturation permits fast and large Ca²⁺ rises near release sites beneath the synaptic ribbon that can trigger multiquantal EPSCs. We conclude that, by restricting the available presynaptic volume, the ribbon may be creating conditions for the synchronous release of a small cohort of docked vesicles.
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46
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HICHIRI K, SHIRAI O, KANO K. Influence of Inhalation Anesthetics on Ion Transport across a Planar Bilayer Lipid Membrane. ANAL SCI 2012; 28:45-9. [DOI: 10.2116/analsci.28.45] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- Kei HICHIRI
- Division of Applied Life Science, Graduate School of Agriculture, Kyoto University
| | - Osamu SHIRAI
- Division of Applied Life Science, Graduate School of Agriculture, Kyoto University
| | - Kenji KANO
- Division of Applied Life Science, Graduate School of Agriculture, Kyoto University
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47
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Gross LCM, Heron AJ, Baca SC, Wallace MI. Determining membrane capacitance by dynamic control of droplet interface bilayer area. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:14335-42. [PMID: 21978255 DOI: 10.1021/la203081v] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
By making dynamic changes to the area of a droplet interface bilayer (DIB), we are able to measure the specific capacitance of lipid bilayers with improved accuracy and precision over existing methods. The dependence of membrane specific capacitance on the chain-length of the alkane oil present in the bilayer is similar to that observed in black lipid membranes. In contrast to conventional artificial bilayers, DIBs are not confined by an aperture, which enables us to determine that the dependence of whole bilayer capacitance on applied potential is predominantly a result of a spontaneous increase in bilayer area. This area change arises from the creation of new bilayer at the three phase interface and is driven by changes in surface tension with applied potential that can be described by the Young-Lippmann equation. By accounting for this area change, we are able to determine the proportion of the capacitance dependence that arises from a change in specific capacitance with applied potential. This method provides a new tool with which to investigate the vertical compression of the bilayer and understand the changes in bilayer thickness with applied potential. We find that, for 1,2-diphytanoyl-sn-glycero-3-phosphocholine membranes in hexadecane, specific bilayer capacitance varies by 0.6-1.5% over an applied potential of ±100 mV.
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Affiliation(s)
- Linda C M Gross
- Department of Chemistry, University of Oxford, Chemistry Research Laboratory, Mansfield Road, Oxford OX1 3TA
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48
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Electrochemical analysis of the interactions and reactivity of ferrocene-based drugs with a lipid environment: A qualitative overview. Inorganica Chim Acta 2011. [DOI: 10.1016/j.ica.2011.04.030] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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49
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Hirano M, Takeuchi Y, Matsumori N, Murata M, Ide T. Channels Formed by Amphotericin B Covalent Dimers Exhibit Rectification. J Membr Biol 2011; 240:159-64. [DOI: 10.1007/s00232-011-9354-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2011] [Accepted: 03/01/2011] [Indexed: 11/24/2022]
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50
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Interaction of siglec protein with glycolipids in a lipid bilayer deposited on a gold electrode surface. J Electroanal Chem (Lausanne) 2010. [DOI: 10.1016/j.jelechem.2010.03.033] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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