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Kataoka-Hamai C. Triacylglycerol-droplet-induced bilayer spontaneous curvature in giant unilamellar vesicles. Biophys J 2024; 123:1857-1868. [PMID: 38822522 DOI: 10.1016/j.bpj.2024.05.030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2024] [Revised: 04/05/2024] [Accepted: 05/29/2024] [Indexed: 06/03/2024] Open
Abstract
This study investigated the incorporation of triacylglycerol droplets in the bilayers of giant unilamellar vesicles (GUVs) using four triacylglycerols and four phosphatidylcholines by confocal laser scanning microscopy. The triacylglycerol droplets were incorporated between the monolayer leaflets of the GUVs. Among the spherical droplets protruding on only one side of the bilayers, the droplets bound to the outer leaflets outnumbered those bound to the inner leaflets. The more frequent droplet binding to the outer leaflet caused transbilayer asymmetry in the droplet surface density. A vesicle consisting of a single-bilayer spherical segment and a double-bilayer spherical segment was also observed. The yield of these vesicles was comparable with or higher than that of the droplet-incorporating GUVs for many of the phosphatidylcholine-triacylglycerol combinations. In a vesicle consisting of single-bilayer and double-bilayer segments, most of the triacylglycerol droplets were localized on the outermost membrane surface along the segment boundary and in the double-bilayer segment. To rationalize the formation of these vesicle structures, we propose that the transbilayer asymmetry in the droplet surface density induces spontaneous curvature of the bilayer, with the bilayer spontaneously bending away from the droplets. Energy calculations performed assuming the existence of spontaneous curvature of the bilayer corroborated the experimentally determined membrane shapes for the vesicles consisting of unilamellar and bilamellar regions.
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Affiliation(s)
- Chiho Kataoka-Hamai
- Research Center for Macromolecules and Biomaterials, National Institute for Materials Science, Tsukuba, Ibaraki, Japan.
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2
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Bhatia T. Stability of multilamellar lipid tubules in excess water. EUROPEAN BIOPHYSICS JOURNAL : EBJ 2023; 52:749-756. [PMID: 37882815 DOI: 10.1007/s00249-023-01686-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2022] [Revised: 08/26/2023] [Accepted: 09/23/2023] [Indexed: 10/27/2023]
Abstract
In the lyotropic phase of lipids with excess water, multilamellar tubules (MLTs) grow from defects. A phenomenological model for the stability of MLTs is developed that is universal and independent of the underlying growth mechanisms of MLTs. The stability of MLTs implies that they are in hydrostatic equilibrium and stable as elastic objects that have compression and bending elasticity. The results show that even with solvent pressure differences of 0.1 atm, the density profile is not significantly altered, so suggesting the stability is due to the trapped solvent. The results are of sufficient value in relation to lamellar stability models and may have implications beyond the described MLT models, especially in other models of membrane systems.
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Affiliation(s)
- Tripta Bhatia
- Department of Physical Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, Knowledge City, Manauli, SAS Nagar, Mohali, Punjab, 140306, India.
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3
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Gahan CG, Van Lehn RC, Blackwell HE, Lynn DM. Interactions of Bacterial Quorum Sensing Signals with Model Lipid Membranes: Influence of Membrane Composition on Membrane Remodeling. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:295-307. [PMID: 36534123 PMCID: PMC10038191 DOI: 10.1021/acs.langmuir.2c02506] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
We report the influence of membrane composition on the multiscale remodeling of multicomponent lipid bilayers initiated by contact with the amphiphilic bacterial quorum sensing signal N-(3-oxo)-dodecanoyl-l-homoserine lactone (3-oxo-C12-AHL) and its anionic headgroup hydrolysis product, 3-oxo-C12-HS. We used fluorescence microscopy and quartz crystal microbalance with dissipation (QCM-D) to characterize membrane reformation that occurs when these amphiphiles are placed in contact with supported lipid bilayers (SLBs) composed of (i) 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) containing varying amounts of cholesterol or (ii) mixtures of DOPC and either 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE, a conical zwitterionic lipid) or 1,2-dioleoyl-sn-glycero-3-phospho-l-serine (DOPS, a model anionic lipid). In general, we observe these mixed-lipid membranes to undergo remodeling events, including the formation and subsequent collapse of long tubules and the formation of hemispherical caps, upon introduction to biologically relevant concentrations of 3-oxo-C12-AHL and 3-oxo-C12-HS in ways that differ substantially from those observed in single-component DOPC membranes. These differences in bilayer reformation and their associated dynamics can be understood in terms of the influence of membrane composition on the time scales of molecular flip-flop, lipid packing defects, and lipid phase segregation in these materials. The lipid components investigated here are representative of classes of lipids that comprise both naturally occurring cell membranes and many useful synthetic soft materials. These studies thus represent a first step toward understanding the ways in which membrane composition can impact interactions with this important class of bacterial signaling molecules.
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Affiliation(s)
- Curran G. Gahan
- Department of Chemical and Biological Engineering, University of Wisconsin–Madison, 1415 Engineering Dr., Madison, WI 53706, USA
| | - Reid C. Van Lehn
- Department of Chemical and Biological Engineering, University of Wisconsin–Madison, 1415 Engineering Dr., Madison, WI 53706, USA
| | - Helen E. Blackwell
- Department of Chemistry, University of Wisconsin–Madison, 1101 University Ave., Madison, WI 53706, USA
| | - David M. Lynn
- Department of Chemical and Biological Engineering, University of Wisconsin–Madison, 1415 Engineering Dr., Madison, WI 53706, USA
- Department of Chemistry, University of Wisconsin–Madison, 1101 University Ave., Madison, WI 53706, USA
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4
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Pinto IS, Cordeiro RA, Faneca H. Polymer- and lipid-based gene delivery technology for CAR T cell therapy. J Control Release 2023; 353:196-215. [PMID: 36423871 DOI: 10.1016/j.jconrel.2022.11.038] [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: 08/31/2022] [Revised: 11/17/2022] [Accepted: 11/19/2022] [Indexed: 11/27/2022]
Abstract
Chimeric antigen receptor T cell (CAR T cell) therapy is a revolutionary approach approved by the FDA and EMA to treat B cell malignancies and multiple myeloma. The production of these T cells has been done through viral vectors, which come with safety concerns, high cost and production challenges, and more recently also through electroporation, which can be extremely cytotoxic. In this context, nanosystems can constitute an alternative to overcome the challenges associated with current methods, resulting in a safe and cost-effective platform. However, the barriers associated with T cells transfection show that the design and engineering of novel approaches in this field are highly imperative. Here, we present an overview from CAR constitution to transfection technologies used in T cells, highlighting the lipid- and polymer-based nanoparticles as a potential delivery platform. Specifically, we provide examples, strengths and weaknesses of nanosystem formulations, and advances in nanoparticle design to improve transfection of T cells. This review will guide the researchers in the design and development of novel nanosystems for next-generation CAR T therapeutics.
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Affiliation(s)
- Inês S Pinto
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal; Department of Medical Sciences, University of Aveiro, Campus Universitário de Santiago, Agra do Castro, 3810-193 Aveiro, Portugal
| | - Rosemeyre A Cordeiro
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal; Institute of Interdisciplinary Research (III), University of Coimbra, Casa Costa Alemão - Pólo II, 3030-789 Coimbra, Portugal
| | - Henrique Faneca
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal; Institute of Interdisciplinary Research (III), University of Coimbra, Casa Costa Alemão - Pólo II, 3030-789 Coimbra, Portugal.
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5
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Stephan MS, Dunsing V, Pramanik S, Chiantia S, Barbirz S, Robinson T, Dimova R. Biomimetic asymmetric bacterial membranes incorporating lipopolysaccharides. Biophys J 2022:S0006-3495(22)03927-3. [PMID: 36523159 DOI: 10.1016/j.bpj.2022.12.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Revised: 11/30/2022] [Accepted: 12/13/2022] [Indexed: 12/23/2022] Open
Abstract
Gram-negative bacteria are equipped with a cell wall that contains a complex matrix of lipids, proteins, and glycans, which form a rigid layer protecting bacteria from the environment. Major components of this outer membrane are the high-molecular weight and amphiphilic lipopolysaccharides (LPSs). They form the extracellular part of a heterobilayer with phospholipids. Understanding LPS properties within the outer membrane is therefore important to develop new antimicrobial strategies. Model systems, such as giant unilamellar vesicles (GUVs), provide a suitable platform for exploring membrane properties and interactions. However, LPS molecules contain large polysaccharide parts that confer high water solubility, which makes LPS incorporation in artificial membranes difficult; this hindrance is exacerbated for LPS with long polysaccharide chains, i.e., the smooth LPS. Here, a novel emulsification step of the inverted emulsion method is introduced to incorporate LPS in the outer or the inner leaflet of GUVs, exclusively. We developed an approach to determine the LPS content on individual GUVs and quantify membrane asymmetry. The asymmetric membranes with outer leaflet LPS show incorporations of 1-16 mol % smooth LPS (corresponding to 16-79 wt %), while vesicles with inner leaflet LPS reach coverages of 2-7 mol % smooth LPS (28-60 wt %). Diffusion coefficient measurements in the obtained GUVs showed that increasing LPS concentrations in the membranes resulted in decreased diffusivity.
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Affiliation(s)
| | - Valentin Dunsing
- Aix-Marseille Université, CNRS, IBDM, Turing Center for Living Systems, Marseille, France; University of Potsdam, Institute of Biochemistry and Biology, Potsdam, Germany
| | - Shreya Pramanik
- Max Planck Institute of Colloids and Interfaces, Potsdam, Germany
| | - Salvatore Chiantia
- University of Potsdam, Institute of Biochemistry and Biology, Potsdam, Germany
| | - Stefanie Barbirz
- Department Humanmedizin, MSB Medical School Berlin, Berlin, Germany
| | - Tom Robinson
- Max Planck Institute of Colloids and Interfaces, Potsdam, Germany.
| | - Rumiana Dimova
- Max Planck Institute of Colloids and Interfaces, Potsdam, Germany.
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Cheppali SK, Dharan R, Sorkin R. Forces of Change: Optical Tweezers in Membrane Remodeling Studies. J Membr Biol 2022; 255:677-690. [PMID: 35616705 DOI: 10.1007/s00232-022-00241-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Accepted: 04/22/2022] [Indexed: 12/24/2022]
Abstract
Optical tweezers allow precise measurement of forces and distances with piconewton and nanometer precision, and have thus been instrumental in elucidating the mechanistic details of various biological processes. Some examples include the characterization of motor protein activity, studies of protein-DNA interactions, and characterizing protein folding trajectories. The use of optical tweezers (OT) to study membranes is, however, much less abundant. Here, we review biophysical studies of membranes that utilize optical tweezers, with emphasis on various assays that have been developed and their benefits and limitations. First, we discuss assays that employ membrane-coated beads, and overview protein-membrane interactions studies based on manipulation of such beads. We further overview a body of studies that make use of a very powerful experimental tool, the combination of OT, micropipette aspiration, and fluorescence microscopy, that allow detailed studies of membrane curvature generation and sensitivity. Finally, we describe studies focused on membrane fusion and fission. We then summarize the overall progress in the field and outline future directions.
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Affiliation(s)
- Sudheer K Cheppali
- Raymond and Beverly Sackler Faculty of Exact Sciences, School of Chemistry, Tel Aviv University, Tel Aviv, Israel.,Center for Physics and Chemistry of Living Systems, Tel Aviv University, Tel Aviv, Israel.,Center for Nanoscience and Nanotechnology, Tel Aviv University, Tel Aviv, Israel.,Center for Light-Matter Interaction, Tel Aviv University, Tel Aviv, Israel
| | - Raviv Dharan
- Raymond and Beverly Sackler Faculty of Exact Sciences, School of Chemistry, Tel Aviv University, Tel Aviv, Israel.,Center for Physics and Chemistry of Living Systems, Tel Aviv University, Tel Aviv, Israel.,Center for Nanoscience and Nanotechnology, Tel Aviv University, Tel Aviv, Israel.,Center for Light-Matter Interaction, Tel Aviv University, Tel Aviv, Israel
| | - Raya Sorkin
- Raymond and Beverly Sackler Faculty of Exact Sciences, School of Chemistry, Tel Aviv University, Tel Aviv, Israel. .,Center for Physics and Chemistry of Living Systems, Tel Aviv University, Tel Aviv, Israel. .,Center for Nanoscience and Nanotechnology, Tel Aviv University, Tel Aviv, Israel. .,Center for Light-Matter Interaction, Tel Aviv University, Tel Aviv, Israel.
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7
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Heterogeneity and deformation behavior of lipid vesicles. Curr Opin Colloid Interface Sci 2022. [DOI: 10.1016/j.cocis.2022.101646] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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8
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Lipowsky R. Multispherical shapes of vesicles highlight the curvature elasticity of biomembranes. Adv Colloid Interface Sci 2022; 301:102613. [PMID: 35228127 DOI: 10.1016/j.cis.2022.102613] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Revised: 01/29/2022] [Accepted: 01/30/2022] [Indexed: 11/01/2022]
Abstract
Giant lipid vesicles form unusual multispherical or "multi-balloon" shapes consisting of several spheres that are connected by membrane necks. Such multispherical shapes have been recently observed when the two sides of the membranes were exposed to different sugar solutions. This sugar asymmetry induced a spontaneous curvature, the sign of which could be reversed by swapping the interior with the exterior solution. Here, previous studies of multispherical shapes are reviewed and extended to develop a comprehensive theory for these shapes. Each multisphere consists of large and small spheres, characterized by two radii, the large-sphere radius, Rl, and the small-sphere radius, Rs. For positive spontaneous curvature, the multisphere can be built up from variable numbers Nl and Ns of large and small spheres. In addition, multispheres consisting of N*=Nl+Ns equally sized spheres are also possible and provide examples for constant-mean-curvature surfaces. For negative spontaneous curvature, all multispheres consist of one large sphere that encloses a variable number Ns of small spheres. These general features of multispheres arise from two basic properties of curvature elasticity: the local shape equation for spherical membrane segments and the stability conditions for closed membrane necks. In addition, the (Nl+Ns)-multispheres can form several (Nl+Ns)-patterns that differ in the way, in which the spheres are mutually connected. These patterns may involve multispherical junctions consisting of individual spheres that are connected to more than two neighboring spheres. The geometry of the multispheres is governed by two polynomial equations which imply that (Nl+Ns)-multispheres can only be formed within a certain restricted range of vesicle volumes. Each (Nl+Ns)-pattern can be characterized by a certain stability regime that depends both on the stability of the closed necks and on the multispherical geometry. Interesting and challenging topics for future studies include the response of multispheres to locally applied external forces, membrane fusion between spheres to create multispherical shapes of higher-genus topology, and the enlarged morphological complexity of multispheres arising from lipid phase separation and intramembrane domains.
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9
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Jin R, Baumgart T. Asymmetric desorption of lipid oxidation products induces membrane bending. SOFT MATTER 2021; 17:7506-7515. [PMID: 34338699 PMCID: PMC8425771 DOI: 10.1039/d1sm00652e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Lipid oxidation, detected in metabolic processes, is induced in excess when the cellular membrane suffers extra oxidative stress. Lipid oxidation can compromise biomembrane function in part through perturbations of lipid packing, membrane permeability, and morphology. Two major types of oxidation products, one with a partially truncated lipid tail with a hydrophilic group at the tail-end, and secondly, a lysolipid (with one of the chains completely truncated) can disturb the membrane bilayer packing significantly. However, they also have an increased tendency to desorb from the membrane. In this study we investigated desorption kinetics of two characteristic lipid oxidation products (PAzePC and 18 : 1 LysoPC) from a model membrane system, and we evaluated the consequences of this process on membrane shape transitions. Using a microfluidic chamber coupled with micropipette aspiration, we observed the incorporation of the two lipids into the membrane of a giant unilamellar vesicle (GUV) and further determined their desorption rates, association rates and flip-flop rates. For both lipids, the desorption is on the time scale of seconds, one to two orders of magnitude faster than their flipping rates. Dilution of the outer solution of the GUVs allowed asymmetric desorption of these two lipids from the GUVs. This process induced lipid number asymmetry and charge asymmetry, specifically for PAzePC containing GUVs, and caused membrane tubulation. Our results indicate that the desorption of lipid oxidation products can alter the local structure of biomembranes and result in morphological changes that may relate to membrane function.
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Affiliation(s)
- Rui Jin
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
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10
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Allolio C, Harries D. Calcium Ions Promote Membrane Fusion by Forming Negative-Curvature Inducing Clusters on Specific Anionic Lipids. ACS NANO 2021; 15:12880-12887. [PMID: 34338519 DOI: 10.1021/acsnano.0c08614] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Vesicles enriched in certain negatively charged lipids, such as phosphatidylserine and PIP2, are known to undergo fusion in the presence of calcium ions without assistance from protein assemblies. Other lipids do not exhibit this propensity, even if they are negatively charged. Using our recently developed methodology, we extract elastic properties of a representative set of lipids. This allows us to trace the origin of lipid-calcium selectivity in membrane fusion to the formation of lipid clusters with long-range correlations that induce negative curvature on the membrane surface. Furthermore, the clusters generate lateral tension in the headgroup region at the membrane surface, concomitantly also stabilizing negative Gaussian curvature. Finally, calcium binding also reduces the orientational polarization of water around the membrane head groups, potentially reducing the hydration force acting between membranes. Binding calcium only weakly increases membrane bending rigidity and tilt moduli, in agreement with experiments. We show how the combined effects of calcium binding to membranes lower the barriers along the fusion pathway that lead to the formation of the fusion stalk as well as the fusion pore.
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Affiliation(s)
- Christoph Allolio
- Charles University, Faculty of Mathematics and Physics, Mathematical Institute, Sokolovská 83, 186 75 Prague 8, Czech Republic
- Institute of Chemistry, The Fritz Haber Center, and The Center for Nanoscience and Nanotechnology, The Hebrew University, E.J. Safra Campus, Jerusalem 9190401, Israel
| | - Daniel Harries
- Institute of Chemistry, The Fritz Haber Center, and The Center for Nanoscience and Nanotechnology, The Hebrew University, E.J. Safra Campus, Jerusalem 9190401, Israel
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Pezeshkian W, Shillcock JC, Ipsen JH. Computational Approaches to Explore Bacterial Toxin Entry into the Host Cell. Toxins (Basel) 2021; 13:toxins13070449. [PMID: 34203472 PMCID: PMC8309782 DOI: 10.3390/toxins13070449] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Revised: 06/18/2021] [Accepted: 06/23/2021] [Indexed: 01/13/2023] Open
Abstract
Many bacteria secrete toxic protein complexes that modify and disrupt essential processes in the infected cell that can lead to cell death. To conduct their action, these toxins often need to cross the cell membrane and reach a specific substrate inside the cell. The investigation of these protein complexes is essential not only for understanding their biological functions but also for the rational design of targeted drug delivery vehicles that must navigate across the cell membrane to deliver their therapeutic payload. Despite the immense advances in experimental techniques, the investigations of the toxin entry mechanism have remained challenging. Computer simulations are robust complementary tools that allow for the exploration of biological processes in exceptional detail. In this review, we first highlight the strength of computational methods, with a special focus on all-atom molecular dynamics, coarse-grained, and mesoscopic models, for exploring different stages of the toxin protein entry mechanism. We then summarize recent developments that are significantly advancing our understanding, notably of the glycolipid–lectin (GL-Lect) endocytosis of bacterial Shiga and cholera toxins. The methods discussed here are also applicable to the design of membrane-penetrating nanoparticles and the study of the phenomenon of protein phase separation at the surface of the membrane. Finally, we discuss other likely routes for future development.
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Affiliation(s)
- Weria Pezeshkian
- Groningen Biomolecular Sciences and Biotechnology Institute and Zernike Institute for Advanced Materials, University of Groningen, 9712 Groningen, The Netherlands
- Correspondence:
| | - Julian C. Shillcock
- Blue Brain Project, Laboratory of Molecular and Chemical Biology of Neurodegeneration, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland;
| | - John H. Ipsen
- MEMPHYS/PhyLife, Department of Physics, Chemistry and Pharmacy (FKF), University of Southern Denmark, Campusvej 55, 5230 Odense, Denmark;
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12
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Bagatolli LA, Stock RP. Lipids, membranes, colloids and cells: A long view. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2021; 1863:183684. [PMID: 34166642 DOI: 10.1016/j.bbamem.2021.183684] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Revised: 06/01/2021] [Accepted: 06/16/2021] [Indexed: 12/13/2022]
Abstract
This paper revisits long-standing ideas about biological membranes in the context of an equally long-standing, but hitherto largely unappreciated, perspective of the cell based on concepts derived from the physics and chemistry of colloids. Specifically, we discuss important biophysical aspects of lipid supramolecular structure to understand how the intracellular milieu may constrain lipid self-assembly. To this end we will develop four lines of thought: first, we will look at the historical development of the current view of cellular structure and physiology, considering also the plurality of approaches that influenced its formative period. Second, we will review recent basic research on the structural and dynamical properties of lipid aggregates as well as the role of phase transitions in biophysical chemistry and cell biology. Third, we will present a general overview of contemporary studies into cellular compartmentalization in the context of a very rich and mostly forgotten general theory of cell physiology called the Association-Induction Hypothesis, which was developed around the time that the current view of cells congealed into its present form. Fourth, we will examine some recent developments in cellular studies, mostly from our laboratory, that raise interesting issues about the dynamical aspects of cell structure and compartmentalization. We will conclude by suggesting what we consider are relevant questions about the nature of cellular processes as emergent phenomena.
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Affiliation(s)
- Luis A Bagatolli
- Instituto de Investigación Médica Mercedes y Martín Ferreyra - INIMEC (CONICET)-Universidad Nacional de Córdoba, Friuli 2434, 5016 Córdoba, Argentina; Departamento de Química Biológica Ranwel Caputto, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina; MEMPHYS - International and Interdisciplinary research network, Denmark.
| | - Roberto P Stock
- MEMPHYS - International and Interdisciplinary research network, Denmark
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Lira RB, Leomil FSC, Melo RJ, Riske KA, Dimova R. To Close or to Collapse: The Role of Charges on Membrane Stability upon Pore Formation. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2021; 8:e2004068. [PMID: 34105299 PMCID: PMC8188222 DOI: 10.1002/advs.202004068] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Revised: 12/14/2020] [Indexed: 05/28/2023]
Abstract
Resealing of membrane pores is crucial for cell survival. Membrane surface charge and medium composition are studied as defining regulators of membrane stability. Pores are generated by electric field or detergents. Giant vesicles composed of zwitterionic and negatively charged lipids mixed at varying ratios are subjected to a strong electric pulse. Interestingly, charged vesicles appear prone to catastrophic collapse transforming them into tubular structures. The spectrum of destabilization responses includes the generation of long-living submicroscopic pores and partial vesicle bursting. The origin of these phenomena is related to the membrane edge tension, which governs pore closure. This edge tension significantly decreases as a function of the fraction of charged lipids. Destabilization of charged vesicles upon pore formation is universal-it is also observed with other poration stimuli. Disruption propensity is enhanced for membranes made of lipids with higher degree of unsaturation. It can be reversed by screening membrane charge in the presence of calcium ions. The observed findings in light of theories of stability and curvature generation are interpreted and mechanisms acting in cells to prevent total membrane collapse upon poration are discussed. Enhanced membrane stability is crucial for the success of electroporation-based technologies for cancer treatment and gene transfer.
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Affiliation(s)
- Rafael B. Lira
- Departamento de BiofísicaUniversidade Federal de São PauloSão Paulo04039‐032Brazil
- Department of Theory and BiosystemsMax Planck Institute of Colloids and InterfacesPotsdam14424Germany
- Present address:
Moleculaire BiofysicaZernike InstituutRijksuniversiteitGroningen9747 AGThe Netherlands
| | | | - Renan J. Melo
- Instituto de FísicaUniversidade de São PauloSão Paulo05508‐090Brazil
| | - Karin A. Riske
- Departamento de BiofísicaUniversidade Federal de São PauloSão Paulo04039‐032Brazil
| | - Rumiana Dimova
- Department of Theory and BiosystemsMax Planck Institute of Colloids and InterfacesPotsdam14424Germany
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Guo X, Steinkühler J, Marin M, Li X, Lu W, Dimova R, Melikyan GB. Interferon-Induced Transmembrane Protein 3 Blocks Fusion of Diverse Enveloped Viruses by Altering Mechanical Properties of Cell Membranes. ACS NANO 2021; 15:8155-8170. [PMID: 33656312 PMCID: PMC8159881 DOI: 10.1021/acsnano.0c10567] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Interferon-induced transmembrane protein 3 (IFITM3) potently inhibits entry of diverse enveloped viruses by trapping the viral fusion at a hemifusion stage, but the underlying mechanism remains unclear. Here, we show that recombinant IFITM3 reconstituted into lipid vesicles induces negative membrane curvature and that this effect maps to its small amphipathic helix (AH). We demonstrate that AH (i) partitions into lipid-disordered domains where IAV fusion occurs, (ii) induces negative membrane curvature, and (iii) increases lipid order and membrane stiffness. These effects on membrane properties correlate with the fusion-inhibitory activity, as targeting the ectopically expressed AH peptide to the cytoplasmic leaflet of the cell plasma membrane diminishes IAV-cell surface fusion induced by exposure to acidic pH. Our results thus imply that IFITM3 inhibits the transition from hemifusion to full fusion by imposing an unfavorable membrane curvature and increasing the order and stiffness of the cytoplasmic leaflet of endosomal membranes. Our findings reveal a universal mechanism by which cells block entry of diverse enveloped viruses.
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Affiliation(s)
- Xiangyang Guo
- Department of Pediatrics, Emory University School of Medicine, Atlanta, GA 30322, United States
| | - Jan Steinkühler
- Max Planck Institute of Colloids and Interfaces, 14424 Potsdam, Germany
| | - Mariana Marin
- Department of Pediatrics, Emory University School of Medicine, Atlanta, GA 30322, United States
| | - Xiang Li
- School of Pharmacy, Second Military Medical University, Shanghai, 200433, China
| | - Wuyuan Lu
- Institute of Human Virology and Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, Maryland 21201, United States
| | - Rumiana Dimova
- Max Planck Institute of Colloids and Interfaces, 14424 Potsdam, Germany
| | - Gregory B. Melikyan
- Department of Pediatrics, Emory University School of Medicine, Atlanta, GA 30322, United States
- Children’s Healthcare of Atlanta, Atlanta, GA 30322, USA
- Corresponding author: Gregory B. Melikyan,
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16
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Wang X, Du H, Wang Z, Mu W, Han X. Versatile Phospholipid Assemblies for Functional Synthetic Cells and Artificial Tissues. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2002635. [PMID: 32830387 DOI: 10.1002/adma.202002635] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Revised: 06/09/2020] [Indexed: 06/11/2023]
Abstract
The bottom-up construction of a synthetic cell from nonliving building blocks capable of mimicking cellular properties and behaviors helps to understand the particular biophysical properties and working mechanisms of a cell. A synthetic cell built in this way possesses defined chemical composition and structure. Since phospholipids are native biomembrane components, their assemblies are widely used to mimic cellular structures. Here, recent developments in the formation of versatile phospholipid assemblies are described, together with the applications of these assemblies for functional membranes (protein reconstituted giant unilamellar vesicles), spherical and nonspherical protoorganelles, and functional synthetic cells, as well as the high-order hierarchical structures of artificial tissues. Their biomedical applications are also briefly summarized. Finally, the challenges and future directions in the field of synthetic cells and artificial tissues based on phospholipid assemblies are proposed.
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Affiliation(s)
- Xuejing Wang
- State Key Laboratory of Urban Water Resource and Environment, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin, 150001, China
| | - Hang Du
- State Key Laboratory of Urban Water Resource and Environment, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin, 150001, China
- Marine Antifouling Engineering Technology Center of Shangdong Province, Harbin Institute of Technology, Weihai, 264209, China
| | - Zhao Wang
- State Key Laboratory of Urban Water Resource and Environment, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin, 150001, China
| | - Wei Mu
- State Key Laboratory of Urban Water Resource and Environment, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin, 150001, China
| | - Xiaojun Han
- State Key Laboratory of Urban Water Resource and Environment, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin, 150001, China
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17
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Agudo-Canalejo J. Particle engulfment by strongly asymmetric membranes with area reservoirs. SOFT MATTER 2021; 17:298-307. [PMID: 32119018 DOI: 10.1039/c9sm02367d] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Biological cells are capable of undergoing extensive shape transformations thanks to the existence of membrane area reservoirs from which they can pull out membrane when required. A particularly relevant example of such membrane remodelling is given by endocytic and phagocytic processes, during which the cell membrane engulfs nano- and micrometer sized particles. Recently, it was shown that cell-like membrane reservoirs can be mimicked in giant vesicles with nanotubes stabilized by strong bilayer asymmetry, as quantified by the membrane's spontaneous curvature. Here, we theoretically investigate particle engulfment by such strongly-asymmetric membranes. We find that, depending on the sign of the spontaneous curvature, the engulfment transition may be continuous or discontinuous. Moreover, we find that, in the case of particle engulfment, the presence of asymmetry-stabilized reservoirs is not well captured by the constant-tension model typically used to describe cell-membrane deformations. This highlights the need for a better understanding of the nature of cellular membrane reservoirs, in order to accurately describe membrane remodelling processes.
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Affiliation(s)
- Jaime Agudo-Canalejo
- Max Planck Institute for Dynamics and Self-Organization (MPIDS), D-37077 Göttingen, Germany.
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18
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Omar YAD, Sahu A, Sauer RA, Mandadapu KK. Nonaxisymmetric Shapes of Biological Membranes from Locally Induced Curvature. Biophys J 2020; 119:1065-1077. [PMID: 32860742 DOI: 10.1016/j.bpj.2020.07.021] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Revised: 07/07/2020] [Accepted: 07/15/2020] [Indexed: 01/24/2023] Open
Abstract
In various biological processes such as endocytosis and caveolae formation, the cell membrane is locally deformed into curved morphologies. Previous models to study membrane morphologies resulting from locally induced curvature often only consider the possibility of axisymmetric shapes-an indeed unphysical constraint. Past studies predict that the cell membrane buds at low resting tensions and stalls at a flat pit at high resting tensions. In this work, we lift the restriction to axisymmetry to study all possible membrane morphologies. Only if the resting tension of the membrane is low, we reproduce axisymmetric membrane morphologies. When the resting tension is moderate to high, we show that 1) axisymmetric membrane pits are unstable and 2) nonaxisymmetric ridge-shaped structures are energetically favorable. Furthermore, we find the interplay between intramembrane viscous flow and the rate of induced curvature affects the membrane's ability to transition into nonaxisymmetric ridges and axisymmetric buds. In particular, we show that axisymmetric buds are favored when the induced curvature is rapidly increased, whereas nonaxisymmetric ridges are favored when the curvature is slowly increased. Our results hold relevant implications for biological processes such as endocytosis and physical phenomena like phase separation in lipid bilayers.
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Affiliation(s)
- Yannick A D Omar
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California.
| | - Amaresh Sahu
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California.
| | - Roger A Sauer
- Aachen Institute for Advanced Study in Computational Engineering Science, RWTH Aachen University, Aachen, Germany.
| | - Kranthi K Mandadapu
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California; Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California.
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19
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Sahoo A, Matysiak S. Microscopic Picture of Calcium-Assisted Lipid Demixing and Membrane Remodeling Using Multiscale Simulations. J Phys Chem B 2020; 124:7327-7335. [PMID: 32786720 DOI: 10.1021/acs.jpcb.0c03067] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
The specificity of anionic phospholipids-calcium ion interaction and lipid demixing has been established as a key regulatory mechanism in several cellular signaling processes. The mechanism and implications of this calcium-assisted demixing have not been elucidated from a microscopic point of view. Here, we present an overview of atomic interactions between calcium and phospholipids that can drive nonideal mixing of lipid molecules in a model lipid bilayer composed of zwitterionic (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC)) and anionic (1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-l-serine (POPS)) lipids with computer simulations at multiple resolutions. Lipid nanodomain formation and growth were driven by calcium-enabled lipid bridging of the charged phosphatidylserine (PS) headgroups, which were favored against inter-POPS dipole interactions. Consistent with several experimental studies of calcium-associated membrane sculpting, our analyses also suggest modifications in local membrane curvature and cross-leaflet couplings as a response to such induced lateral heterogeneity. In addition, reverse mapping to a complementary atomistic description revealed structural insights in the presence of anionic nanodomains, at timescales not accessed by previous computational studies. This work bridges information across multiple scales to reveal a mechanistic picture of calcium ion's impact on membrane biophysics.
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Affiliation(s)
- Abhilash Sahoo
- Biophysics Program, Institute of Physical Science and Technology, University of Maryland, College Park, Maryland 20742, United States
| | - Silvina Matysiak
- Biophysics Program, Institute of Physical Science and Technology, University of Maryland, College Park, Maryland 20742, United States.,Fischell Department of Bioengineering, University of Maryland, College Park, Maryland 20742, United States
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20
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Ali Doosti B, Fjällborg D, Kustanovich K, Jesorka A, Cans AS, Lobovkina T. Generation of interconnected vesicles in a liposomal cell model. Sci Rep 2020; 10:14040. [PMID: 32820180 PMCID: PMC7441142 DOI: 10.1038/s41598-020-70562-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2020] [Accepted: 06/08/2020] [Indexed: 12/04/2022] Open
Abstract
We introduce an experimental method based upon a glass micropipette microinjection technique for generating a multitude of interconnected vesicles (IVs) in the interior of a single giant unilamellar phospholipid vesicle (GUV) serving as a cell model system. The GUV membrane, consisting of a mixture of soybean polar lipid extract and anionic phosphatidylserine, is adhered to a multilamellar lipid vesicle that functions as a lipid reservoir. Continuous IV formation was achieved by bringing a micropipette in direct contact with the outer GUV surface and subjecting it to a localized stream of a Ca2+ solution from the micropipette tip. IVs are rapidly and sequentially generated and inserted into the GUV interior and encapsulate portions of the micropipette fluid content. The IVs remain connected to the GUV membrane and are interlinked by short lipid nanotubes and resemble beads on a string. The vesicle chain-growth from the GUV membrane is maintained for as long as there is the supply of membrane material and Ca2+ solution, and the size of the individual IVs is controlled by the diameter of the micropipette tip. We also demonstrate that the IVs can be co-loaded with high concentrations of neurotransmitter and protein molecules and displaying a steep calcium ion concentration gradient across the membrane. These characteristics are analogous to native secretory vesicles and could, therefore, serve as a model system for studying secretory mechanisms in biological systems.
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Affiliation(s)
- Baharan Ali Doosti
- Department of Chemistry and Chemical Engineering, Chalmers University of Technology, Kemivägen 9, 412 96, Göteborg, Sweden
| | - Daniel Fjällborg
- Department of Chemistry and Chemical Engineering, Chalmers University of Technology, Kemivägen 9, 412 96, Göteborg, Sweden
| | - Kiryl Kustanovich
- Department of Chemistry and Chemical Engineering, Chalmers University of Technology, Kemivägen 9, 412 96, Göteborg, Sweden
| | - Aldo Jesorka
- Department of Chemistry and Chemical Engineering, Chalmers University of Technology, Kemivägen 9, 412 96, Göteborg, Sweden
| | - Ann-Sofie Cans
- Department of Chemistry and Chemical Engineering, Chalmers University of Technology, Kemivägen 9, 412 96, Göteborg, Sweden
| | - Tatsiana Lobovkina
- Department of Chemistry and Chemical Engineering, Chalmers University of Technology, Kemivägen 9, 412 96, Göteborg, Sweden.
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21
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Valentine ML, Cardenas AE, Elber R, Baiz CR. Calcium-Lipid Interactions Observed with Isotope-Edited Infrared Spectroscopy. Biophys J 2020; 118:2694-2702. [PMID: 32362342 DOI: 10.1016/j.bpj.2020.04.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Revised: 03/20/2020] [Accepted: 04/10/2020] [Indexed: 01/17/2023] Open
Abstract
Calcium ions bind to lipid membranes containing anionic lipids; however, characterizing the specific ion-lipid interactions in multicomponent membranes has remained challenging because it requires nonperturbative lipid-specific probes. Here, using a combination of isotope-edited infrared spectroscopy and molecular dynamics simulations, we characterize the effects of a physiologically relevant (2 mM) Ca2+ concentration on zwitterionic phosphatidylcholine and anionic phosphatidylserine lipids in mixed lipid membranes. We show that Ca2+ alters hydrogen bonding between water and lipid headgroups by forming a coordination complex involving the lipid headgroups and water. These interactions distort interfacial water orientations and prevent hydrogen bonding with lipid ester carbonyls. We demonstrate, experimentally, that these effects are more pronounced for the anionic phosphatidylserine lipids than for zwitterionic phosphatidylcholine lipids in the same membrane.
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Affiliation(s)
- Mason L Valentine
- Department of Chemistry, University of Texas at Austin, Austin, Texas
| | - Alfredo E Cardenas
- Department of Chemistry, University of Texas at Austin, Austin, Texas; Institute for Computational Engineering and Sciences, University of Texas at Austin, Austin, Texas
| | - Ron Elber
- Department of Chemistry, University of Texas at Austin, Austin, Texas; Institute for Computational Engineering and Sciences, University of Texas at Austin, Austin, Texas
| | - Carlos R Baiz
- Department of Chemistry, University of Texas at Austin, Austin, Texas.
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22
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Zhu N, Wang D, Xie F, Qin M, Lin Z, Wang Y. Fabrication and Characterization of Calcium-Phosphate Lipid System for Potential Dental Application. Front Chem 2020; 8:161. [PMID: 32269987 PMCID: PMC7111464 DOI: 10.3389/fchem.2020.00161] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2020] [Accepted: 02/24/2020] [Indexed: 12/15/2022] Open
Abstract
Lipid has been widely studied as a vehicle and loading vector, but there have been no reports of any such related application in the dental field. The purpose of this research was to fabricate and characterize a nano-size calcium-phosphate lipid (CL) system as a potential vehicle in dental regeneration study, wherein the biocompatibility with dental pulp stem cells (DPSCs) was evaluated. The effect of CL on DPSCs proliferation was analyzed by a CCK-8 assay, and the anti-inflammatory effect was investigated by quantitative polymerase chain reaction (qPCR). Moreover, the effect of CL on odontogenic differentiation of inflamed DPSCs (iDPSCs) was studied by Alizarin red staining, tissue-non-specific alkaline phosphatase (TNAP) staining, qPCR, and western blot analyses. The results of this study showed that CL did not affect the proliferation of DPSCs, it down-regulated the inflammatory-associated markers (IL-1β, IL-6, TNF-α, COX-2) of DPSCs treated with Escherichia coli lipopolysaccharide (LPS), and enhanced the in-vitro odontogenic differentiation potential of iDPSCs. This novel biomaterial has a broad application prospect for its bioactivity and flexible physical property, and thus represents a promising pulpal regeneration material.
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Affiliation(s)
- Ningxin Zhu
- Department of Pediatric Dentistry, School and Hospital of Stomatology, Peking University, Beijing, China
| | - Dan Wang
- Department of Pediatric Dentistry, School and Hospital of Stomatology, Peking University, Beijing, China
| | - Fei Xie
- Department of Pediatric Dentistry, School and Hospital of Stomatology, Peking University, Beijing, China
| | - Man Qin
- Department of Pediatric Dentistry, School and Hospital of Stomatology, Peking University, Beijing, China
| | - Zhiqiang Lin
- Beijing Key Laboratory of Tumor Systems Biology, School of Basic Medical Sciences, Institute of Systems Biomedicine, Peking University Health Science Center, Beijing, China
| | - Yuanyuan Wang
- Department of Pediatric Dentistry, School and Hospital of Stomatology, Peking University, Beijing, China
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23
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Pezeshkian W, Ipsen JH. Fluctuations and conformational stability of a membrane patch with curvature inducing inclusions. SOFT MATTER 2019; 15:9974-9981. [PMID: 31754667 DOI: 10.1039/c9sm01762c] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Membranes with curvature inducing inclusions display a range of cooperative phenomena, which can be linked to biomembrane function, e.g. membrane tubulation, vesiculation, softening and spontaneous tension. We investigate how these phenomena are related for a fluctuating, framed membrane through analysis of a descretized membrane model by Monte Carlo simulation techniques. The membrane model is based on a dynamically triangulated surface equipped with non-interacting, up-down symmetry breaking inclusions where only terms coupled linearly to mean-curvature are maintained. We show that the lateral configurational entropy plays a key role for the mechanical properties of the semi-flexible membrane, e.g. a pronounced softening at intermediate inclusion coverages of the membrane and generation of membrane tension. Tensionless framed membranes will remain quasi-flat up to some threshold coverage, where a shape instability occurs with formation of pearling or tubular membranes, which below full coverage is associated with segregation of inclusions between the curved and flat membrane geometries. For inclusions with preference for highly curved membranes the instability appears at dilute inclusion coverages and is accompanied by strong configurational fluctuations.
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Affiliation(s)
- Weria Pezeshkian
- Groningen Biomolecular Sciences and Biotechnology Institute and Zernike Institute for Advanced Materials, University of Groningen, Groningen, The Netherlands.
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24
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Kustanovich K, Yantchev V, Doosti BA, Gözen I, Jesorka A. A microfluidics-integrated impedance/surface acoustic resonance tandem sensor. SENSING AND BIO-SENSING RESEARCH 2019. [DOI: 10.1016/j.sbsr.2019.100291] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
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25
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Stephens AD, Liu PZ, Kandula V, Chen H, Almassalha LM, Herman C, Backman V, O’Halloran T, Adam SA, Goldman RD, Banigan EJ, Marko JF. Physicochemical mechanotransduction alters nuclear shape and mechanics via heterochromatin formation. Mol Biol Cell 2019; 30:2320-2330. [PMID: 31365328 PMCID: PMC6743459 DOI: 10.1091/mbc.e19-05-0286] [Citation(s) in RCA: 66] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Accepted: 06/11/2019] [Indexed: 12/12/2022] Open
Abstract
The nucleus houses, organizes, and protects chromatin to ensure genome integrity and proper gene expression, but how the nucleus adapts mechanically to changes in the extracellular environment is poorly understood. Recent studies have revealed that extracellular physical stresses induce chromatin compaction via mechanotransductive processes. We report that increased extracellular multivalent cations lead to increased heterochromatin levels through activation of mechanosensitive ion channels (MSCs), without large-scale cell stretching. In cells with perturbed chromatin or lamins, this increase in heterochromatin suppresses nuclear blebbing associated with nuclear rupture and DNA damage. Through micromanipulation force measurements, we show that this increase in heterochromatin increases chromatin-based nuclear rigidity, which protects nuclear morphology and function. In addition, transduction of elevated extracellular cations rescues nuclear morphology in model and patient cells of human diseases, including progeria and the breast cancer model cell line MDA-MB-231. We conclude that nuclear mechanics, morphology, and function can be modulated by cell sensing of the extracellular environment through MSCs and consequent changes to histone modification state and chromatin-based nuclear rigidity.
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Affiliation(s)
- Andrew D. Stephens
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208
| | - Patrick Z. Liu
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208
| | - Viswajit Kandula
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208
| | - Haimei Chen
- Department of Chemistry, Northwestern University, Evanston, IL 60208
| | - Luay M. Almassalha
- Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208
| | - Cameron Herman
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208
| | - Vadim Backman
- Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208
| | - Thomas O’Halloran
- Department of Chemistry, Northwestern University, Evanston, IL 60208
| | - Stephen A. Adam
- Department of Cell and Molecular Biology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611
| | - Robert D. Goldman
- Department of Cell and Molecular Biology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611
| | - Edward J. Banigan
- Department of Physics and Astronomy, Northwestern University, Evanston, IL 60208
- Institute for Medical Engineering and Science and Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - John F. Marko
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208
- Department of Physics and Astronomy, Northwestern University, Evanston, IL 60208
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26
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Pezeshkian W, König M, Marrink SJ, Ipsen JH. A Multi-Scale Approach to Membrane Remodeling Processes. Front Mol Biosci 2019; 6:59. [PMID: 31396522 PMCID: PMC6664084 DOI: 10.3389/fmolb.2019.00059] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Accepted: 07/08/2019] [Indexed: 12/31/2022] Open
Abstract
We present a multi-scale simulation procedure to describe membrane-related biological processes that span over a wide range of length scales. At macroscopic length-scale, a membrane is described as a flexible thin film modeled by a dynamic triangulated surface with its spatial conformations governed by an elastic energy containing only a few model parameters. An implicit protein model allows us to include complex effects of membrane-protein interactions in the macroscopic description. The gist of this multi-scale approach is a scheme to calibrate the implicit protein model using finer scale simulation techniques e.g., all atom and coarse grain molecular dynamics. We previously used this approach and properly described the formation of membrane tubular invaginations upon binding of B-subunit of Shiga toxin. Here, we provide a perspective of our multi-scale approach, summarizing its main features and sketching possible routes for future development.
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Affiliation(s)
- Weria Pezeshkian
- Groningen Biomolecular Sciences and Biotechnology Institute and Zernike Institute for Advanced Materials, University of Groningen, Groningen, Netherlands
| | - Melanie König
- Groningen Biomolecular Sciences and Biotechnology Institute and Zernike Institute for Advanced Materials, University of Groningen, Groningen, Netherlands
| | - Siewert J Marrink
- Groningen Biomolecular Sciences and Biotechnology Institute and Zernike Institute for Advanced Materials, University of Groningen, Groningen, Netherlands
| | - John H Ipsen
- Department of Physics, Chemistry and Pharmacy, Center for Biomembrane Physics (MEMPHYS), University of Southern Denmark, Odense, Denmark
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27
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Han Y, Lin H, Ding M, Li R, Shi T. Flow-induced translocation of vesicles through a narrow pore. SOFT MATTER 2019; 15:3307-3314. [PMID: 30892355 DOI: 10.1039/c9sm00116f] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
We use finite element method to investigate the flow-induced translocation of vesicles through a narrow pore from a dynamic point of view. In order to complete the coupling between fluid flow and the vesicle membranes, we employ the fluid-structure interactions with the arbitrary Lagrangian-Eulerian method. Our results demonstrate that the vesicle shows similar shape change from bullet-like to dumbbell-like, dumbbell-like to bulb-like, and bulb-like to parachute-like if it is pushed by flow field to pass through a narrow pore smaller than its size. We further find that the strain energy exhibits a higher peak and a lower peak in the whole translocation process, where the higher peak corresponds to the dumbbell-like shape and the lower peak corresponds to the parachute-like shape due to more stretching of the membrane for the dumbbell-like shape than that of the parachute-like shape. The translocation time of the vesicle from one side to the other side of the narrow pore decreases with the increase of inlet velocity, but the strain energy exhibits an increase, which implies that the vesicle needs more time to complete the translocation with the lower inlet velocity, but the requirement for the mechanical properties of the membrane is lower. Our work answers the mapping between the positions of the vesicles and deformed states with the stress distribution and change of strain energy, which can provide helpful information on the utilization of vesicles in pharmaceutical, chemical, and physiological processes.
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Affiliation(s)
- Yunlong Han
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, P. R. China.
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28
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Trewby W, Faraudo J, Voïtchovsky K. Long-lived ionic nano-domains can modulate the stiffness of soft interfaces. NANOSCALE 2019; 11:4376-4384. [PMID: 30801089 DOI: 10.1039/c8nr06339g] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Metal ions underpin countless processes at bio-interfaces, including maintaining electroneutrality, modifying mechanical properties and driving bioenergetic activity. These processes are typically described by ions behaving as independently diffusing point charges. Here we show that Na+ and K+ ions instead spontaneously form correlated nanoscale networks that evolve over seconds at the interface with an anionic bilayer in solution. Combining single-ion level atomic force microscopy and molecular dynamic simulations we investigate the configuration and dynamics of Na+, K+, and Rb+ at the lipid surface. We identify two distinct ionic states: the well-known direct electrostatic interaction with lipid headgroups and a water-mediated interaction that can drive the formation of remarkably long-lived ionic networks which evolve over many seconds. We show that this second state induces ionic network formation via correlative ion-ion interactions that generate an effective energy well of -0.4kBT/ion. These networks locally reduce the stiffness of the membrane, providing a spontaneous mechanism for tuning its mechanical properties with nanoscale precision. The ubiquity of water-mediated interactions suggest that our results have far-reaching implications for controlling the properties of soft interfaces.
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Affiliation(s)
- William Trewby
- University of Durham, Physics Department, Durham DH1 3LE, UK.
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29
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Petit JD, Immel F, Lins L, Bayer EM. Lipids or Proteins: Who Is Leading the Dance at Membrane Contact Sites? FRONTIERS IN PLANT SCIENCE 2019; 10:198. [PMID: 30846999 PMCID: PMC6393330 DOI: 10.3389/fpls.2019.00198] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Accepted: 02/05/2019] [Indexed: 05/19/2023]
Abstract
Understanding the mode of action of membrane contact sites (MCSs) across eukaryotic organisms at the near-atomic level to infer function at the cellular and tissue levels is a challenge scientists are currently facing. These peculiar systems dedicated to inter-organellar communication are perfect examples of cellular processes where the interplay between lipids and proteins is critical. In this mini review, we underline the link between membrane lipid environment, the recruitment of proteins at specialized membrane domains and the function of MCSs. More precisely, we want to give insights on the crucial role of lipids in defining the specificity of plant endoplasmic reticulum (ER)-plasma membrane (PM) MCSs and we further propose approaches to study them at multiple scales. Our goal is not so much to go into detailed description of MCSs, as there are numerous focused reviews on the subject, but rather try to pinpoint the critical elements defining those structures and give an original point of view by considering the subject from a near-atomic angle with a focus on lipids. We review current knowledge as to how lipids can define MCS territories, play a role in the recruitment and function of the MCS-associated proteins and in turn, how the lipid environment can be modified by proteins.
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Affiliation(s)
- Jules D. Petit
- UMR5200 CNRS, Laboratory of Membrane Biogenesis, University of Bordeaux, Villenave d’Ornon, France
- Laboratoire de Biophysique Moléculaire aux Interfaces, TERRA Research Centre, GX ABT, Université de Liège, Liège, Belgium
| | - Françoise Immel
- UMR5200 CNRS, Laboratory of Membrane Biogenesis, University of Bordeaux, Villenave d’Ornon, France
| | - Laurence Lins
- Laboratoire de Biophysique Moléculaire aux Interfaces, TERRA Research Centre, GX ABT, Université de Liège, Liège, Belgium
| | - Emmanuelle M. Bayer
- UMR5200 CNRS, Laboratory of Membrane Biogenesis, University of Bordeaux, Villenave d’Ornon, France
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30
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Abstract
Intracellular delivery of biological agents such as peptides, proteins, and nucleic acids generally rely on the endocytic pathway as the major uptake mechanism, resulting in their entrapment inside the endosome and lysosome. The recent discovery of cell-penetrating molecules of exceptionally high endosomal escape and cytosolic delivery efficiencies and elucidation of their mechanism of action represent major breakthroughs in this field. In this Topical Review, we provide an overview of the recent progress in understanding and enhancing the endosomal escape process and the new opportunities opened up by these recent findings.
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Affiliation(s)
- Dehua Pei
- Department of Chemistry and Biochemistry, The Ohio State University, 484 West 12 Avenue, Columbus, Ohio 43210, USA
| | - Marina Buyanova
- Department of Chemistry and Biochemistry, The Ohio State University, 484 West 12 Avenue, Columbus, Ohio 43210, USA
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31
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Karimi M, Steinkühler J, Roy D, Dasgupta R, Lipowsky R, Dimova R. Asymmetric Ionic Conditions Generate Large Membrane Curvatures. NANO LETTERS 2018; 18:7816-7821. [PMID: 30456959 DOI: 10.1021/acs.nanolett.8b03584] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Biological membranes possess intrinsic asymmetry. This asymmetry is associated not only with leaflet composition in terms of membrane species but also with differences in the cytosolic and periplasmic solutions containing macromolecules and ions. There has been a long quest for understanding the effect of ions on the physical and morphological properties of membranes. Here, we elucidate the changes in the mechanical properties of membranes exposed to asymmetric buffer conditions and the associated curvature generation. As a model system, we used giant unilamellar vesicles (GUVs) with asymmetric salt and sugar solutions on the two sides of the membrane. We aspirated the GUVs into micropipettes and attached small beads to their membranes. An optical tweezer was used to exert a local force on a bead, thereby pulling out a membrane tube from the vesicle. The assay allowed us to measure the spontaneous curvature and the bending rigidity of the bilayer in the presence of different ions and sugar. At low sugar/salt (inside/out) concentrations, the membrane spontaneous curvature generated by NaCl and KCl is close to zero, but negative in the presence of LiCl. In the latter case, the membrane bulges away from the salt solution. At high sugar/salt conditions, the membranes were observed to become more flexible and the spontaneous curvature was enhanced to even more negative values, comparable to those generated by some proteins. Our findings reveal the reshaping role of alkali chlorides on biomembranes.
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Affiliation(s)
- Marzieh Karimi
- Department of Theory and Bio-Systems , Max Planck Institute of Colloids and Interfaces , Science Park Golm, 14424 Potsdam , Germany
| | - Jan Steinkühler
- Department of Theory and Bio-Systems , Max Planck Institute of Colloids and Interfaces , Science Park Golm, 14424 Potsdam , Germany
| | - Debjit Roy
- Department of Theory and Bio-Systems , Max Planck Institute of Colloids and Interfaces , Science Park Golm, 14424 Potsdam , Germany
| | - Raktim Dasgupta
- Department of Theory and Bio-Systems , Max Planck Institute of Colloids and Interfaces , Science Park Golm, 14424 Potsdam , Germany
- Laser Biomedical Applications Section , Raja Ramanna Centre for Advanced Technology , 452013 Indore , India
| | - Reinhard Lipowsky
- Department of Theory and Bio-Systems , Max Planck Institute of Colloids and Interfaces , Science Park Golm, 14424 Potsdam , Germany
| | - Rumiana Dimova
- Department of Theory and Bio-Systems , Max Planck Institute of Colloids and Interfaces , Science Park Golm, 14424 Potsdam , Germany
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32
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Hallock MJ, Greenwood AI, Wang Y, Morrissey JH, Tajkhorshid E, Rienstra CM, Pogorelov TV. Calcium-Induced Lipid Nanocluster Structures: Sculpturing of the Plasma Membrane. Biochemistry 2018; 57:6897-6905. [PMID: 30456950 DOI: 10.1021/acs.biochem.8b01069] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The plasma membrane of the cell is a complex, tightly regulated, heterogeneous environment shaped by proteins, lipids, and small molecules. Ca2+ ions are important cellular messengers, spatially separated from anionic lipids. After cell injury, disease, or apoptotic events, anionic lipids are externalized to the outer leaflet of the plasma membrane and encounter Ca2+, resulting in dramatic changes in the plasma membrane structure and initiation of signaling cascades. Despite the high chemical and biological significance, the structures of lipid-Ca2+ nanoclusters are still not known. Previously, we demonstrated by solid-state nuclear magnetic resonance (NMR) spectroscopy that upon binding to Ca2+, individual phosphatidylserine lipids populate two distinct yet-to-be-characterized structural environments. Here, we concurrently employ extensive all-atom molecular dynamics (MD) simulations with our accelerated membrane mimetic and detailed NMR measurements to identify lipid-Ca2+ nanocluster conformations. We find that major structural characteristics of these nanoclusters, including interlipid pair distances and chemical shifts, agree with observable NMR parameters. Simulations reveal that lipid-ion nanoclusters are shaped by two characteristic, long-lived lipid structures induced by divalent Ca2+. Using ab initio quantum mechanical calculations of chemical shifts on MD-captured lipid-ion complexes, we show that computationally observed conformations are validated by experimental NMR data. Both NMR measurements of diluted specifically labeled lipids and MD simulations reveal that the basic structural unit that reshapes the membrane is a Ca2+-coordinated phosphatidylserine tetramer. Our combined computational and experimental approach presented here can be applied to other complex systems in which charged membrane-active molecular agents leave structural signatures on lipids.
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Affiliation(s)
- Michael J Hallock
- School of Chemical Sciences , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States
| | - Alexander I Greenwood
- Department of Chemistry , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States
| | - Yan Wang
- Department of Biochemistry , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States
| | - James H Morrissey
- Department of Biological Chemistry , University of Michigan Medical School , Ann Arbor , Michigan 48103 , United States
| | - Emad Tajkhorshid
- Department of Chemistry , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States.,Department of Biochemistry , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States.,Beckman Institute for Advanced Science and Technology , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States.,Center for Biophysics and Quantitative Biology , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States
| | - Chad M Rienstra
- Department of Chemistry , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States.,Department of Biochemistry , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States.,Beckman Institute for Advanced Science and Technology , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States.,Center for Biophysics and Quantitative Biology , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States
| | - Taras V Pogorelov
- School of Chemical Sciences , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States.,Department of Biochemistry , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States.,Beckman Institute for Advanced Science and Technology , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States.,Center for Biophysics and Quantitative Biology , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States.,National Center for Supercomputing Applications , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States
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33
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Kodama A, Morandi M, Ebihara R, Jimbo T, Toyoda M, Sakuma Y, Imai M, Puff N, Angelova MI. Migration of Deformable Vesicles Induced by Ionic Stimuli. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:11484-11494. [PMID: 30156845 DOI: 10.1021/acs.langmuir.8b02105] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We have investigated the dynamics of phospholipid vesicles composed of 1,2-dioleoyl- sn-glycero-3-phosphocholine triggered by ionic stimuli using electrolytes such as CaCl2, NaCl, and NaOH. The ionic stimuli induce two characteristic vesicle dynamics, deformation due to the ion binding to the lipids in the outer leaflet of the vesicle and migration due to the concentration gradient of ions, that is, diffusiophoresis or the interfacial energy gradient mechanism. We examined the deformation pathway for each electrolyte as a function of time and analyzed it based on the surface dissociation model and the area difference elasticity model, which reveals the change of the cross-sectional area of the phospholipid by the ion binding. The metal ions such as Ca2+ and Na+ encourage inward budding deformation by decreasing the cross-sectional area of a lipid, whereas the hydroxide ion (OH-) encourages outward budding deformation by increasing the cross-sectional area of a lipid. When we microinjected these electrolytes toward the vesicles, a strong coupling between the deformation and the migration of the vesicle was observed for CaCl2 and NaOH, whereas for NaCl, the coupling was very weak. This difference probably originates from the binding constants of the ions.
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Affiliation(s)
- Atsuji Kodama
- Department of Physics, Graduate School of Science , Tohoku University , Aoba, Aramaki, Aoba, Sendai 980-8578 , Japan
| | - Mattia Morandi
- Department of Physics, Graduate School of Science , Tohoku University , Aoba, Aramaki, Aoba, Sendai 980-8578 , Japan
| | - Ryuta Ebihara
- Department of Physics, Graduate School of Science , Tohoku University , Aoba, Aramaki, Aoba, Sendai 980-8578 , Japan
| | - Takehiro Jimbo
- Department of Physics, Graduate School of Science , Tohoku University , Aoba, Aramaki, Aoba, Sendai 980-8578 , Japan
| | - Masayuki Toyoda
- Department of Physics, Graduate School of Science , Tohoku University , Aoba, Aramaki, Aoba, Sendai 980-8578 , Japan
| | - Yuka Sakuma
- Department of Physics, Graduate School of Science , Tohoku University , Aoba, Aramaki, Aoba, Sendai 980-8578 , Japan
| | - Masayuki Imai
- Department of Physics, Graduate School of Science , Tohoku University , Aoba, Aramaki, Aoba, Sendai 980-8578 , Japan
| | - Nicolas Puff
- Laboratory Matière et Systèmes Complexes (MSC) UMR 7057 CNRS , Sorbonne Paris Cité - Paris 7 , F-75013 Paris , France
- Faculty of Science and Engineering - Paris 6 / Sorbonne University , F-75005 Paris , France
| | - Miglena I Angelova
- Laboratory Matière et Systèmes Complexes (MSC) UMR 7057 CNRS , Sorbonne Paris Cité - Paris 7 , F-75013 Paris , France
- Faculty of Science and Engineering - Paris 6 / Sorbonne University , F-75005 Paris , France
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34
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Valentine ML, Cardenas AE, Elber R, Baiz CR. Physiological Calcium Concentrations Slow Dynamics at the Lipid-Water Interface. Biophys J 2018; 115:1541-1551. [PMID: 30269885 DOI: 10.1016/j.bpj.2018.08.044] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Revised: 08/20/2018] [Accepted: 08/27/2018] [Indexed: 02/07/2023] Open
Abstract
Phospholipids can interact strongly with ions at physiological concentrations, and these interactions can alter membrane properties. Here, we describe the effects of calcium ions on the dynamics in phospholipid membranes. We used a combination of time-resolved ultrafast two-dimensional infrared spectroscopy and molecular dynamics simulations. We found that millimolar Ca2+ concentrations lead to slower fluctuations in the local environment at the lipid-water interface of membranes with phosphatidylserine. The effect was only observed in bilayers containing anionic phosphatidylserine; membranes composed of only zwitterionic phosphatidylcholine did not experience a slowdown. Local water dynamics were measured using the ester groups as label-free probes and were found to be up to 50% slower with 2.5 mM Ca2+. Molecular dynamics simulations show that Ca2+ primarily binds to the carboxylate group of phosphatidylserines. These findings have implications for apoptotic and diseased cells in which phosphatidylserine is exposed to extracellular calcium and for the biophysical effects of divalent cations on lipid bilayers.
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Affiliation(s)
- Mason L Valentine
- Department of Chemistry, University of Texas at Austin, Austin, Texas
| | - Alfredo E Cardenas
- Department of Chemistry, University of Texas at Austin, Austin, Texas; Institute for Computational Engineering and Sciences, University of Texas at Austin, Austin, Texas
| | - Ron Elber
- Department of Chemistry, University of Texas at Austin, Austin, Texas; Institute for Computational Engineering and Sciences, University of Texas at Austin, Austin, Texas
| | - Carlos R Baiz
- Department of Chemistry, University of Texas at Austin, Austin, Texas.
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35
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Steinkühler J, De Tillieux P, Knorr RL, Lipowsky R, Dimova R. Charged giant unilamellar vesicles prepared by electroformation exhibit nanotubes and transbilayer lipid asymmetry. Sci Rep 2018; 8:11838. [PMID: 30087440 PMCID: PMC6081385 DOI: 10.1038/s41598-018-30286-z] [Citation(s) in RCA: 68] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Accepted: 07/24/2018] [Indexed: 12/22/2022] Open
Abstract
Giant unilamellar vesicles (GUVs) are increasingly used as a versatile research tool to investigate membrane structure, morphology and phase state. In these studies, GUV preparation is typically enhanced by an externally applied electric field, a process called electroformation. We find that upon osmotic deflation, GUVs electroformed from charged and neutral lipids exhibit inward pointing lipid nanotubes, suggesting negative spontaneous curvature of the membrane. By quenching a fluorescent analog of the charged lipid, zeta potential measurements and experiments with the lipid marker annexin A5, we show that electroformed GUVs exhibit an asymmetric lipid distribution across the bilayer leaflets. The asymmetry is lost either after storing electroformed GUVs at room temperature for one day or by applying higher voltages and temperatures during electroformation. GUVs having the same lipid composition but grown via gel-assisted swelling do not show asymmetric lipid distribution. We discuss possible mechanisms for the generation and relaxation of lipid asymmetry, as well as implications for studies using electroformed vesicles. The observed effects allow to control the molecular assembly of lipid bilayer leaflets. Vesicle tubulation as reported here is an example of protein-free reshaping of membranes and is caused by compositional lipid asymmetry between leaflets.
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Affiliation(s)
- Jan Steinkühler
- Department of Theory and Bio-Systems, Max Planck Institute of Colloids and Interfaces, Science Park Golm, 14424, Potsdam, Germany
| | - Philippe De Tillieux
- Department of Theory and Bio-Systems, Max Planck Institute of Colloids and Interfaces, Science Park Golm, 14424, Potsdam, Germany
- Department of Electrical Engineering, Polytechnique Montreal, Montreal, Quebec, H3T 1J4, Canada
| | - Roland L Knorr
- Department of Theory and Bio-Systems, Max Planck Institute of Colloids and Interfaces, Science Park Golm, 14424, Potsdam, Germany
| | - Reinhard Lipowsky
- Department of Theory and Bio-Systems, Max Planck Institute of Colloids and Interfaces, Science Park Golm, 14424, Potsdam, Germany
| | - Rumiana Dimova
- Department of Theory and Bio-Systems, Max Planck Institute of Colloids and Interfaces, Science Park Golm, 14424, Potsdam, Germany.
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36
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Ali Doosti B, Cans AS, Jeffries GDM, Lobovkina T. Membrane Remodeling of Giant Vesicles in Response to Localized Calcium Ion Gradients. J Vis Exp 2018. [PMID: 30059020 PMCID: PMC6126466 DOI: 10.3791/57789] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
In a wide variety of fundamental cell processes, such as membrane trafficking and apoptosis, cell membrane shape transitions occur concurrently with local variations in calcium ion concentration. The main molecular components involved in these processes have been identified; however, the specific interplay between calcium ion gradients and the lipids within the cell membrane is far less known, mainly due to the complex nature of biological cells and the difficultly of observation schemes. To bridge this gap, a synthetic approach is successfully implemented to reveal the localized effect of calcium ions on cell membrane mimics. Establishing a mimic to resemble the conditions within a cell is a severalfold problem. First, an adequate biomimetic model with appropriate dimensions and membrane composition is required to capture the physical properties of cells. Second, a micromanipulation setup is needed to deliver a small amount of calcium ions to a particular membrane location. Finally, an observation scheme is required to detect and record the response of the lipid membrane to the external stimulation. This article offers a detailed biomimetic approach for studying the calcium ion-membrane interaction, where a lipid vesicle system, consisting of a giant unilamellar vesicle (GUV) connected to a multilamellar vesicle (MLV), is exposed to a localized calcium gradient formed using a microinjection system. The dynamics of the ionic influence on the membrane were observed using fluorescence microscopy and recorded at video frame rates. As a result of the membrane stimulation, highly curved membrane tubular protrusions (MTPs) formed inside the GUV, oriented away from the membrane. The described approach induces the remodeling of the lipid membrane and MTP production in an entirely contactless and controlled manner. This approach introduces a means to address the details of calcium ion-membrane interactions, providing new avenues to study the mechanisms of cell membrane reshaping.
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Affiliation(s)
- Baharan Ali Doosti
- Department of Chemistry and Chemical Engineering, Chalmers University of Technology
| | - Ann-Sofie Cans
- Department of Chemistry and Chemical Engineering, Chalmers University of Technology
| | - Gavin D M Jeffries
- Department of Chemistry and Chemical Engineering, Chalmers University of Technology
| | - Tatsiana Lobovkina
- Department of Chemistry and Chemical Engineering, Chalmers University of Technology;
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37
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Boye TL, Jeppesen JC, Maeda K, Pezeshkian W, Solovyeva V, Nylandsted J, Simonsen AC. Annexins induce curvature on free-edge membranes displaying distinct morphologies. Sci Rep 2018; 8:10309. [PMID: 29985397 PMCID: PMC6037701 DOI: 10.1038/s41598-018-28481-z] [Citation(s) in RCA: 67] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Accepted: 06/19/2018] [Indexed: 12/31/2022] Open
Abstract
Annexins are a family of proteins characterized by their ability to bind anionic membranes in response to Ca2+-activation. They are involved in a multitude of cellular functions including vesiculation and membrane repair. Here, we investigate the effect of nine annexins (ANXA1-ANXA7, ANXA11, ANXA13) on negatively charged double supported membrane patches with free edges. We find that annexin members can be classified according to the membrane morphology they induce and matching a dendrogam of the annexin family based on full amino acid sequences. ANXA1 and ANXA2 induce membrane folding and blebbing initiated from membrane structural defects inside patches while ANXA6 induces membrane folding originating both from defects and from the membrane edges. ANXA4 and ANXA5 induce cooperative roll-up of the membrane starting from free edges, producing large rolls. In contrast, ANXA3 and ANXA13 roll the membrane in a fragmented manner producing multiple thin rolls. In addition to rolling, ANXA7 and ANXA11 are characterized by their ability to form fluid lenses localized between the membrane leaflets. A shared feature necessary for generating these morphologies is the ability to induce membrane curvature on free edged anionic membranes. Consequently, induction of membrane curvature may be a significant property of the annexin protein family that is important for their function.
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Affiliation(s)
- Theresa Louise Boye
- Membrane Integrity Group, Unit for Cell Death and Metabolism, Danish Cancer Society Research Center, Strandboulevarden 49, DK-2100, Copenhagen, Denmark
| | - Jonas Camillus Jeppesen
- University of Southern Denmark (SDU), Campusvej 55, DK-5230, Odense M, Denmark.,Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Odense, Denmark
| | - Kenji Maeda
- Membrane Integrity Group, Unit for Cell Death and Metabolism, Danish Cancer Society Research Center, Strandboulevarden 49, DK-2100, Copenhagen, Denmark
| | - Weria Pezeshkian
- University of Southern Denmark (SDU), Campusvej 55, DK-5230, Odense M, Denmark.,Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Odense, Denmark
| | - Vita Solovyeva
- University of Southern Denmark (SDU), Campusvej 55, DK-5230, Odense M, Denmark.,Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Jesper Nylandsted
- Membrane Integrity Group, Unit for Cell Death and Metabolism, Danish Cancer Society Research Center, Strandboulevarden 49, DK-2100, Copenhagen, Denmark.,Department of Cellular and Molecular Medicine, Faculty of Health Sciences, University of Copenhagen, DK-2200, Copenhagen N, Denmark
| | - Adam Cohen Simonsen
- University of Southern Denmark (SDU), Campusvej 55, DK-5230, Odense M, Denmark. .,Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Odense, Denmark.
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38
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Bhatia T. An image-processing method to detect sub-optical features based on understanding noise in intensity measurements. EUROPEAN BIOPHYSICS JOURNAL : EBJ 2018; 47:531-538. [PMID: 29392337 PMCID: PMC6006265 DOI: 10.1007/s00249-017-1273-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Revised: 11/11/2017] [Accepted: 12/19/2017] [Indexed: 12/04/2022]
Abstract
Accurate quantitative analysis of image data requires that we distinguish between fluorescence intensity (true signal) and the noise inherent to its measurements to the extent possible. We image multilamellar membrane tubes and beads that grow from defects in the fluid lamellar phase of the lipid 1,2-dioleoyl-sn-glycero-3-phosphocholine dissolved in water and water-glycerol mixtures by using fluorescence confocal polarizing microscope. We quantify image noise and determine the noise statistics. Understanding the nature of image noise also helps in optimizing image processing to detect sub-optical features, which would otherwise remain hidden. We use an image-processing technique "optimum smoothening" to improve the signal-to-noise ratio of features of interest without smearing their structural details. A high SNR renders desired positional accuracy with which it is possible to resolve features of interest with width below optical resolution. Using optimum smoothening, the smallest and the largest core diameter detected is of width [Formula: see text] and [Formula: see text] nm, respectively, discussed in this paper. The image-processing and analysis techniques and the noise modeling discussed in this paper can be used for detailed morphological analysis of features down to sub-optical length scales that are obtained by any kind of fluorescence intensity imaging in the raster mode.
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Affiliation(s)
- Tripta Bhatia
- Raman Research Institute (RRI), Sir C. V. Raman Avenue, Bangalore, 560080, India.
- Max Planck Institute of Colloids and Interfaces, Theory and Bio-Systems, 14424, Potsdam, Germany.
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39
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Kirejev V, Ali Doosti B, Shaali M, Jeffries GDM, Lobovkina T. Contactless Stimulation and Control of Biomimetic Nanotubes by Calcium Ion Gradients. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2018; 14:e1703541. [PMID: 29665219 DOI: 10.1002/smll.201703541] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Revised: 03/12/2018] [Indexed: 06/08/2023]
Abstract
Membrane tubular structures are important communication pathways between cells and cellular compartments. Studying these structures in their native environment is challenging, due to the complexity of membranes and varying chemical conditions within and outside of the cells. This work demonstrates that a calcium ion gradient, applied to a synthetic lipid nanotube, triggers lipid flow directed toward the application site, resulting in the formation of a bulge aggregate. This bulge can be translated in a contactless manner by moving a calcium ion source along the lipid nanotube. Furthermore, entrapment of polystyrene nanobeads within the bulge does not tamper the bulge movement and allows transporting of the nanoparticle cargo along the lipid nanotube. In addition to the synthetic lipid nanotubes, the response of cell plasma membrane tethers to local calcium ion stimulation is investigated. The directed membrane transport in these tethers is observed, but with slower kinetics in comparison to the synthetic lipid nanotubes. The findings of this work demonstrate a novel and contactless mode of transport in lipid nanotubes, guided by local exposure to calcium ions. The observed lipid nanotube behavior can advance the current understanding of the cell membrane tubular structures, which are constantly reshaped during dynamic cellular processes.
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Affiliation(s)
- Vladimir Kirejev
- Department of Chemistry and Chemical Engineering, Chalmers University of Technology, Kemivägen 9, SE-412 96, Göteborg, Sweden
| | - Baharan Ali Doosti
- Department of Chemistry and Chemical Engineering, Chalmers University of Technology, Kemivägen 9, SE-412 96, Göteborg, Sweden
| | - Mehrnaz Shaali
- Department of Chemistry and Chemical Engineering, Chalmers University of Technology, Kemivägen 9, SE-412 96, Göteborg, Sweden
| | - Gavin D M Jeffries
- Department of Chemistry and Chemical Engineering, Chalmers University of Technology, Kemivägen 9, SE-412 96, Göteborg, Sweden
| | - Tatsiana Lobovkina
- Department of Chemistry and Chemical Engineering, Chalmers University of Technology, Kemivägen 9, SE-412 96, Göteborg, Sweden
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