1
|
Kondrashov OV, Akimov SA. Alteration of Average Thickness of Lipid Bilayer by Membrane-Deforming Inclusions. Biomolecules 2023; 13:1731. [PMID: 38136602 PMCID: PMC10741968 DOI: 10.3390/biom13121731] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2023] [Revised: 11/29/2023] [Accepted: 11/30/2023] [Indexed: 12/24/2023] Open
Abstract
Thickness of lipid bilayer membranes is a key physical parameter determining membrane permeability and stability with respect to formation of through pores. Most membrane inclusions or impurities like amphipathic peptides, transmembrane peptides, lipid inclusions of a different molecular shape, lipid domains, and protein-lipid domains, locally deform the membrane. The detailed structure of the locally deformed region of the membrane is a kind of "fingerprint" for the inclusion type. However, most experimental methods allow determining only averaged parameters of membranes with incorporated inclusions, thus preventing the direct obtaining of the characteristics of the inclusion. Here we developed a model that allows the obtaining of characteristic parameters of three types of membrane inclusions (amphipathic peptides, transmembrane peptides, monolayer lipid patches) from experimentally observable dependencies of the average thickness of lipid bilayer on the surface concentration of the inclusions. In the case of amphipathic peptides, the model provided the peptide parameters that were in qualitative agreement with the available experimental data.
Collapse
Affiliation(s)
- Oleg V. Kondrashov
- Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 31/4 Leninskiy Prospekt, 119071 Moscow, Russia
| | - Sergey A. Akimov
- Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 31/4 Leninskiy Prospekt, 119071 Moscow, Russia
| |
Collapse
|
2
|
Shendrik P, Golani G, Dharan R, Schwarz US, Sorkin R. Membrane Tension Inhibits Lipid Mixing by Increasing the Hemifusion Stalk Energy. ACS NANO 2023; 17:18942-18951. [PMID: 37669531 PMCID: PMC7615193 DOI: 10.1021/acsnano.3c04293] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2023] [Accepted: 08/23/2023] [Indexed: 09/07/2023]
Abstract
Fusion of biological membranes is fundamental in various physiological events. The fusion process involves several intermediate stages with energy barriers that are tightly dependent on the mechanical and physical properties of the system, one of which is membrane tension. As previously established, the late stages of fusion, including hemifusion diaphragm and pore expansions, are favored by membrane tension. However, a current understanding of how the energy barrier of earlier fusion stages is affected by membrane tension is lacking. Here, we apply a newly developed experimental approach combining micropipette-aspirated giant unilamellar vesicles and optically trapped membrane-coated beads, revealing that membrane tension inhibits lipid mixing. We show that lipid mixing is 6 times slower under a tension of 0.12 mN/m compared with tension-free membranes. Furthermore, using continuum elastic theory, we calculate the dependence of the hemifusion stalk formation energy on membrane tension and intermembrane distance and find the increase in the corresponding energy barrier to be 1.6 kBT in our setting, which can explain the increase in lipid mixing time delay. Finally, we show that tension can be a significant factor in the stalk energy if the pre-fusion intermembrane distance is on the order of several nanometers, while for membranes that are tightly docked, tension has a negligible effect.
Collapse
Affiliation(s)
- Petr Shendrik
- School
of Chemistry, Raymond & Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv, 6997801, Israel
- Center
of Physics and Chemistry of Living Systems, Tel Aviv University, Tel Aviv, 6997801, Israel
| | - Gonen Golani
- Institute
for Theoretical Physics and BioQuant Center for Quantitative Biology, Heidelberg University, 69120, Heidelberg, Germany
| | - Raviv Dharan
- School
of Chemistry, Raymond & Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv, 6997801, Israel
- Center
of Physics and Chemistry of Living Systems, Tel Aviv University, Tel Aviv, 6997801, Israel
| | - Ulrich S. Schwarz
- Institute
for Theoretical Physics and BioQuant Center for Quantitative Biology, Heidelberg University, 69120, Heidelberg, Germany
| | - Raya Sorkin
- School
of Chemistry, Raymond & Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv, 6997801, Israel
- Center
of Physics and Chemistry of Living Systems, Tel Aviv University, Tel Aviv, 6997801, Israel
| |
Collapse
|
3
|
Friedrichs J, Helbig R, Hilsenbeck J, Pandey PR, Sommer JU, Renner LD, Pompe T, Werner C. Entropic repulsion of cholesterol-containing layers counteracts bioadhesion. Nature 2023; 618:733-739. [PMID: 37344647 DOI: 10.1038/s41586-023-06033-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Accepted: 03/30/2023] [Indexed: 06/23/2023]
Abstract
Control of adhesion is a striking feature of living matter that is of particular interest regarding technological translation1-3. We discovered that entropic repulsion caused by interfacial orientational fluctuations of cholesterol layers restricts protein adsorption and bacterial adhesion. Moreover, we found that intrinsically adhesive wax ester layers become similarly antibioadhesive when containing small quantities (under 10 wt%) of cholesterol. Wetting, adsorption and adhesion experiments, as well as atomistic simulations, showed that repulsive characteristics depend on the specific molecular structure of cholesterol that encodes a finely balanced fluctuating reorientation at the interface of unconstrained supramolecular assemblies: layers of cholesterol analogues differing only in minute molecular variations showed markedly different interfacial mobility and no antiadhesive effects. Also, orientationally fixed cholesterol layers did not resist bioadhesion. Our insights provide a conceptually new physicochemical perspective on biointerfaces and may guide future material design in regulation of adhesion.
Collapse
Affiliation(s)
- Jens Friedrichs
- Institute of Biofunctional Polymer Materials, Leibniz Institute of Polymer Research Dresden, Dresden, Germany
| | - Ralf Helbig
- Institute of Biofunctional Polymer Materials, Leibniz Institute of Polymer Research Dresden, Dresden, Germany
| | - Julia Hilsenbeck
- Institute of Biofunctional Polymer Materials, Leibniz Institute of Polymer Research Dresden, Dresden, Germany
| | - Prithvi Raj Pandey
- Institute of Theory of Polymers, Leibniz Institute of Polymer Research Dresden, Dresden, Germany
| | - Jens-Uwe Sommer
- Institute of Theory of Polymers, Leibniz Institute of Polymer Research Dresden, Dresden, Germany
- Cluster of Excellence Physics of Life and Center of Regenerative Therapies Dresden, Technische Universität Dresden, Dresden, Germany
| | - Lars David Renner
- Institute of Biofunctional Polymer Materials, Leibniz Institute of Polymer Research Dresden, Dresden, Germany
| | - Tilo Pompe
- Institute of Biofunctional Polymer Materials, Leibniz Institute of Polymer Research Dresden, Dresden, Germany
- Institute for Biochemistry, Leipzig University, Leipzig, Germany
| | - Carsten Werner
- Institute of Biofunctional Polymer Materials, Leibniz Institute of Polymer Research Dresden, Dresden, Germany.
- Cluster of Excellence Physics of Life and Center of Regenerative Therapies Dresden, Technische Universität Dresden, Dresden, Germany.
| |
Collapse
|
4
|
Palaia I, Paraschiv A, Debets VE, Storm C, Šarić A. Durotaxis of Passive Nanoparticles on Elastic Membranes. ACS NANO 2021; 15:15794-15802. [PMID: 34550677 DOI: 10.1101/2021.04.01.438065] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The transport of macromolecules and nanoscopic particles to a target cellular site is a crucial aspect in many physiological processes. This directional motion is generally controlled via active mechanical and chemical processes. Here we show, by means of molecular dynamics simulations and an analytical theory, that completely passive nanoparticles can exhibit directional motion when embedded in nonuniform mechanical environments. Specifically, we study the motion of a passive nanoparticle adhering to a mechanically nonuniform elastic membrane. We observe a nonmonotonic affinity of the particle to the membrane as a function of the membrane's rigidity, which results in the particle transport. This transport can be both up or down the rigidity gradient, depending on the absolute values of the rigidities that the gradient spans across. We conclude that rigidity gradients can be used to direct average motion of passive macromolecules and nanoparticles on deformable membranes, resulting in the preferential accumulation of the macromolecules in regions of certain mechanical properties.
Collapse
Affiliation(s)
- Ivan Palaia
- Department of Physics and Astronomy, Institute for the Physics of Living Systems, University College London, London WC1E 6BT, United Kingdom
- MRC Laboratory for Molecular Cell Biology, University College London, London WC1E 6BT, United Kingdom
| | - Alexandru Paraschiv
- Department of Physics and Astronomy, Institute for the Physics of Living Systems, University College London, London WC1E 6BT, United Kingdom
- MRC Laboratory for Molecular Cell Biology, University College London, London WC1E 6BT, United Kingdom
| | - Vincent E Debets
- Department of Applied Physics, Eindhoven University of Technology, 5600 MB Eindhoven, The Netherlands
- Institute for Complex Molecular Systems, Eindhoven University of Technology, 5600 MB Eindhoven, The Netherlands
| | - Cornelis Storm
- Department of Applied Physics, Eindhoven University of Technology, 5600 MB Eindhoven, The Netherlands
- Institute for Complex Molecular Systems, Eindhoven University of Technology, 5600 MB Eindhoven, The Netherlands
| | - Anđela Šarić
- Department of Physics and Astronomy, Institute for the Physics of Living Systems, University College London, London WC1E 6BT, United Kingdom
- MRC Laboratory for Molecular Cell Biology, University College London, London WC1E 6BT, United Kingdom
| |
Collapse
|
5
|
Navarro-Partida J, Castro-Castaneda CR, Santa Cruz-Pavlovich FJ, Aceves-Franco LA, Guy TO, Santos A. Lipid-Based Nanocarriers as Topical Drug Delivery Systems for Intraocular Diseases. Pharmaceutics 2021; 13:pharmaceutics13050678. [PMID: 34065059 PMCID: PMC8151015 DOI: 10.3390/pharmaceutics13050678] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2021] [Revised: 04/19/2021] [Accepted: 04/23/2021] [Indexed: 12/13/2022] Open
Abstract
Effective drug delivery to intraocular tissues remains a great challenge due to complex anatomical and physiological barriers that selectively limit the entry of drugs into the eye. To overcome these challenges, frequent topical application and regular intravitreal injections are currently used to achieve the desired drug concentrations into the eye. However, the repetitive installation or recurrent injections may result in several side effects. Recent advancements in the field of nanoparticle-based drug delivery have demonstrated promising results for topical ophthalmic nanotherapies in the treatment of intraocular diseases. Studies have revealed that nanocarriers enhance the intraocular half-life and bioavailability of several therapies including proteins, peptides and genetic material. Amongst the array of nanoparticles available nowadays, lipid-based nanosystems have shown an increased efficiency and feasibility in topical formulations, making them an important target for constant and thorough research in both preclinical and clinical practice. In this review, we will cover the promising lipid-based nanocarriers used in topical ophthalmic formulations for intraocular drug delivery.
Collapse
Affiliation(s)
- Jose Navarro-Partida
- Tecnologico de Monterrey, Escuela de Medicina y Ciencias de la Salud, Campus Guadalajara, P.C., Zapopan 45138, Mexico; (J.N.-P.); (C.R.C.-C.); (F.J.S.C.-P.); (L.A.A.-F.); (T.O.G.)
- Centro de Retina Medica y Quirurgica, S.C., Centro Medico Puerta de Hierro, P.C., Zapopan 45116, Mexico
| | - Carlos Rodrigo Castro-Castaneda
- Tecnologico de Monterrey, Escuela de Medicina y Ciencias de la Salud, Campus Guadalajara, P.C., Zapopan 45138, Mexico; (J.N.-P.); (C.R.C.-C.); (F.J.S.C.-P.); (L.A.A.-F.); (T.O.G.)
| | - Francisco J. Santa Cruz-Pavlovich
- Tecnologico de Monterrey, Escuela de Medicina y Ciencias de la Salud, Campus Guadalajara, P.C., Zapopan 45138, Mexico; (J.N.-P.); (C.R.C.-C.); (F.J.S.C.-P.); (L.A.A.-F.); (T.O.G.)
| | - Luis Abraham Aceves-Franco
- Tecnologico de Monterrey, Escuela de Medicina y Ciencias de la Salud, Campus Guadalajara, P.C., Zapopan 45138, Mexico; (J.N.-P.); (C.R.C.-C.); (F.J.S.C.-P.); (L.A.A.-F.); (T.O.G.)
- Centro de Retina Medica y Quirurgica, S.C., Centro Medico Puerta de Hierro, P.C., Zapopan 45116, Mexico
| | - Tomer Ori Guy
- Tecnologico de Monterrey, Escuela de Medicina y Ciencias de la Salud, Campus Guadalajara, P.C., Zapopan 45138, Mexico; (J.N.-P.); (C.R.C.-C.); (F.J.S.C.-P.); (L.A.A.-F.); (T.O.G.)
| | - Arturo Santos
- Tecnologico de Monterrey, Escuela de Medicina y Ciencias de la Salud, Campus Guadalajara, P.C., Zapopan 45138, Mexico; (J.N.-P.); (C.R.C.-C.); (F.J.S.C.-P.); (L.A.A.-F.); (T.O.G.)
- Centro de Retina Medica y Quirurgica, S.C., Centro Medico Puerta de Hierro, P.C., Zapopan 45116, Mexico
- Correspondence: ; Tel.: +52-(33)-36-69-30-00 (ext. 2540)
| |
Collapse
|
6
|
Ben Messaoud G, Le Griel P, Hermida-Merino D, Baccile N. Effects of pH, temperature and shear on the structure-property relationship of lamellar hydrogels from microbial glucolipids probed by in situ rheo-SAXS. SOFT MATTER 2020; 16:2540-2551. [PMID: 32095796 DOI: 10.1039/c9sm02494h] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Lipid lamellar hydrogels are a class of soft materials composed of a defectuous lipid lamellar phase, where defects are classically stabilized by polymer or surfactant inclusions in lipid membranes. We have recently shown that bolaform microbial glucolipids, composed of a single glucose headgroup and a C18:0 fatty acid, with the carboxylic acid group located opposite to glucose, spontaneously form lamellar hydrogels at room temperature below pH 8. In this work, we combine rheology with small angle X-ray scattering (SAXS), rheo-SAXS, to correlate, in situ, the structural and mechanical properties of microbial glycolipid lamellar hydrogels upon application of three different stimuli: pH, temperature and a shear rate. In all cases we find unusual structural features of the lamellar phase if compared to classical phospholipid lamellar structures: reducing pH from alkaline to acidic induces a sol-to-gel transition during which an increasing elastic modulus is associated with an oscillatory evolution of lamellar d(100) spacing; temperature above Tm and increasing shear induce the formation of spherulitic crumpled domains, instead of a classically-expected lamellar-to-vesicle or lamellar-to-onion phase transitions.
Collapse
Affiliation(s)
- Ghazi Ben Messaoud
- Sorbonne Université, Centre National de la Recherche Scientifique, Laboratoire de Chimie de la Matière Condensée de Paris, LCMCP, F-75005 Paris, France.
| | | | | | | |
Collapse
|
7
|
Blackmore J, Shrivastava S, Sallet J, Butler CR, Cleveland RO. Ultrasound Neuromodulation: A Review of Results, Mechanisms and Safety. ULTRASOUND IN MEDICINE & BIOLOGY 2019; 45:1509-1536. [PMID: 31109842 PMCID: PMC6996285 DOI: 10.1016/j.ultrasmedbio.2018.12.015] [Citation(s) in RCA: 245] [Impact Index Per Article: 49.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2018] [Revised: 12/13/2018] [Accepted: 12/29/2018] [Indexed: 05/03/2023]
Abstract
Ultrasonic neuromodulation is a rapidly growing field, in which low-intensity ultrasound (US) is delivered to nervous system tissue, resulting in transient modulation of neural activity. This review summarizes the findings in the central and peripheral nervous systems from mechanistic studies in cell culture to cognitive behavioral studies in humans. The mechanisms by which US mechanically interacts with neurons and could affect firing are presented. An in-depth safety assessment of current studies shows that parameters for the human studies fall within the safety envelope for US imaging. Challenges associated with accurately targeting US and monitoring the response are described. In conclusion, the literature supports the use of US as a safe, non-invasive brain stimulation modality with improved spatial localization and depth targeting compared with alternative methods. US neurostimulation has the potential to be used both as a scientific instrument to investigate brain function and as a therapeutic modality to modulate brain activity.
Collapse
Affiliation(s)
- Joseph Blackmore
- Institute of Biomedical Engineering, Department of Engineering Science, University of Oxford, Roosevelt Drive, Oxford, UK
| | - Shamit Shrivastava
- Institute of Biomedical Engineering, Department of Engineering Science, University of Oxford, Roosevelt Drive, Oxford, UK
| | - Jerome Sallet
- Wellcome Centre for Integrative Nueroimaging, Department of Experimental Psychology, University of Oxford, Oxford, UK
| | - Chris R Butler
- Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, Oxford, UK
| | - Robin O Cleveland
- Institute of Biomedical Engineering, Department of Engineering Science, University of Oxford, Roosevelt Drive, Oxford, UK.
| |
Collapse
|
8
|
Yasser M, Teaima M, El-Nabarawi M, El-Monem RA. Cubosomal based oral tablet for controlled drug delivery of telmisartan: formulation, in-vitro evaluation and in-vivo comparative pharmacokinetic study in rabbits. Drug Dev Ind Pharm 2019; 45:981-994. [PMID: 30865478 DOI: 10.1080/03639045.2019.1590392] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
A nanoparticulate system; cubosomes has been suggested to support the controlled release of Telmisartan (TEL), a poorly water-soluble medication. Four distinctive formulae were selected according to the results of three estimated responses. The liquid cubosomes were successfully adsorbed onto Aerosil 380 to form granules. The formulae were evaluated for their flow properties. The best granules were compressed into tablets suitable for oral administration. The tablets were evaluated for its performance. The in vivo study of the best selected cubosomal tablets was checked after oral administration in the blood of albino rabbits utilizing an HPLC method. Results revealed that the highest EE was shown in formulae C5 (59.68 ± 1.3). All the prepared formulae had particle size less than 500 nm with PDI < 0.5 and the highest zeta potential results were observed in C5, C7, C9, C11 and C12 (>30 mv). A7 and A9 prepared using Aerosil 380 showed a perfect flowability. After 1 h of dissolution testing, the commercial product showed a 66% drug release while the release of all cubosomal formulae didn't exceed 35% during the first hour reaching a 85% of the drug released at the end of 24 h. A7 was selected for the in vivo study; Tmax of TEL absorption is increased for cubosomal formula by three folds indicating sustained release pattern. The relative bioavailability is also increased by 2.6 fold. The investigation proposed the rationality of cubosome to figure an effective controlled release tablets to improve its bioavailability and expand its activity.
Collapse
Affiliation(s)
- Mohamed Yasser
- a Department of Pharmaceutics and Industrial Pharmacy , Horus University , New Damietta , Egypt.,b Department of Pharmaceutics and Industrial Pharmacy , Sinai University , North Sinai , Egypt
| | - Mahmoud Teaima
- c Department of Pharmaceutics and Industrial Pharmacy, Faculty of Pharmacy , Cairo University , Cairo , Egypt
| | - Mohamed El-Nabarawi
- c Department of Pharmaceutics and Industrial Pharmacy, Faculty of Pharmacy , Cairo University , Cairo , Egypt
| | - Rehab Abd El-Monem
- d Department of Pharmaceutics and Industrial Pharmacy, Faculty of Pharmacy , Misr University for Science and Technology , 6th of October , Egypt
| |
Collapse
|
9
|
Buchholz S, Deuschel JD, Kurt N, Schweiger F. Probability to be positive for the membrane model in dimensions 2 and 3. ELECTRONIC COMMUNICATIONS IN PROBABILITY 2019. [DOI: 10.1214/19-ecp245] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
|
10
|
Steinkühler J, Różycki B, Alvey C, Lipowsky R, Weikl TR, Dimova R, Discher DE. Membrane fluctuations and acidosis regulate cooperative binding of 'marker of self' protein CD47 with the macrophage checkpoint receptor SIRPα. J Cell Sci 2018; 132:jcs.216770. [PMID: 29777034 DOI: 10.1242/jcs.216770] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Accepted: 05/09/2018] [Indexed: 12/22/2022] Open
Abstract
Cell-cell interactions that result from membrane proteins binding weakly in trans can cause accumulations in cis that suggest cooperativity and thereby an acute sensitivity to environmental factors. The ubiquitous 'marker of self' protein CD47 binds weakly to SIRPα on macrophages, which leads to accumulation of SIRPα (also known as SHPS-1, CD172A and SIRPA) at phagocytic synapses and ultimately to inhibition of engulfment of 'self' cells - including cancer cells. We reconstituted this macrophage checkpoint with GFP-tagged CD47 on giant vesicles generated from plasma membranes and then imaged vesicles adhering to SIRPα immobilized on a surface. CD47 diffusion is impeded near the surface, and the binding-unbinding events reveal cooperative interactions as a concentration-dependent two-dimensional affinity. Membrane fluctuations out-of-plane link cooperativity to membrane flexibility with suppressed fluctuations in the vicinity of bound complexes. Slight acidity (pH 6) stiffens membranes, diminishes cooperative interactions and also reduces 'self' signaling of cancer cells in phagocytosis. Sensitivity of cell-cell interactions to microenvironmental factors - such as the acidity of tumors and other diseased or inflamed sites - can thus arise from the collective cooperative properties of flexible membranes.This article has an associated First Person interview with the first author of the paper.
Collapse
Affiliation(s)
- Jan Steinkühler
- Molecular & Cell Biophysics Lab, University of Pennsylvania, Philadelphia, 19104 PA, USA.,Theory and Bio-Systems, Max Planck Institut of Colloids and Interfaces, Science Park Golm, 14424 Potsdam, Germany
| | - Bartosz Różycki
- Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warsaw, Poland
| | - Cory Alvey
- Molecular & Cell Biophysics Lab, University of Pennsylvania, Philadelphia, 19104 PA, USA
| | - Reinhard Lipowsky
- Theory and Bio-Systems, Max Planck Institut of Colloids and Interfaces, Science Park Golm, 14424 Potsdam, Germany
| | - Thomas R Weikl
- Theory and Bio-Systems, Max Planck Institut of Colloids and Interfaces, Science Park Golm, 14424 Potsdam, Germany
| | - Rumiana Dimova
- Theory and Bio-Systems, Max Planck Institut of Colloids and Interfaces, Science Park Golm, 14424 Potsdam, Germany
| | - Dennis E Discher
- Molecular & Cell Biophysics Lab, University of Pennsylvania, Philadelphia, 19104 PA, USA
| |
Collapse
|
11
|
Abstract
The nuclear envelope (NE) presents a physical boundary between the cytoplasm and the nucleoplasm, sandwiched in between two highly active systems inside the cell: cytoskeleton and chromatin. NE defines the shape and size of the cell nucleus, which increases during the cell cycle, accommodating for chromosome decondensation followed by genome duplication. In this work, we study nuclear shape fluctuations at short time scales of seconds in human cells. Using spinning disk confocal microscopy, we observe fast fluctuations of the NE, visualized by fluorescently labeled lamin A, and of the chromatin globule surface (CGS) underneath the NE, visualized by fluorescently labeled histone H2B. Our findings reveal that fluctuation amplitudes of both CGS and NE monotonously decrease during the cell cycle, serving as a reliable cell cycle stage indicator. Remarkably, we find that, while CGS and NE typically fluctuate in phase, they do exhibit localized regions of out-of-phase motion, which lead to separation of NE and CGS. To explore the mechanism behind these shape fluctuations, we use biochemical perturbations. We find the shape fluctuations of CGS and NE to be both thermally and actively driven, the latter caused by forces from chromatin and cytoskeleton. Such undulations might affect gene regulation as well as contribute to the anomalously high rates of nuclear transport by, e.g., stirring of molecules next to NE, or increasing flux of molecules through the nuclear pores.
Collapse
|
12
|
Tabaei SR, Gillissen JJJ, Kim MC, Ho JCS, Liedberg B, Parikh AN, Cho NJ. Brownian Dynamics of Electrostatically Adhering Small Vesicles to a Membrane Surface Induces Domains and Probes Viscosity. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:5445-5450. [PMID: 27164321 DOI: 10.1021/acs.langmuir.6b00985] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Using single-particle tracking, we investigate the interaction of small unilamellar vesicles (SUVs) that are electrostatically tethered to the freestanding membrane of a giant unilamellar vesicle (GUV). We find that the surface mobility of the GUV-riding SUVs is Brownian, insensitive to the bulk viscosity, vesicle size, and vesicle fluidity but strongly altered by the viscosity of the underlying membrane. Analyzing the diffusional behavior of SUVs within the Saffman-Delbrück model for the dynamics of membrane inclusions supports the notion that the mobility of the small vesicles is coupled to that of dynamically induced lipid clusters within the target GUV membrane. The reversible binding also offers a nonperturbative means for measuring the viscosity of biomembranes, which is an important parameter in cell physiology and function.
Collapse
Affiliation(s)
- Seyed R Tabaei
- School of Materials Science and Engineering, Nanyang Technological University , 50 Nanyang Avenue 639798, Singapore
- Centre for Biomimetic Sensor Science, Nanyang Technological University , 50 Nanyang Drive 637553, Singapore
| | - Jurriaan J J Gillissen
- School of Materials Science and Engineering, Nanyang Technological University , 50 Nanyang Avenue 639798, Singapore
- Centre for Biomimetic Sensor Science, Nanyang Technological University , 50 Nanyang Drive 637553, Singapore
| | - Min Chul Kim
- School of Materials Science and Engineering, Nanyang Technological University , 50 Nanyang Avenue 639798, Singapore
- Centre for Biomimetic Sensor Science, Nanyang Technological University , 50 Nanyang Drive 637553, Singapore
| | - James C S Ho
- School of Materials Science and Engineering, Nanyang Technological University , 50 Nanyang Avenue 639798, Singapore
- Centre for Biomimetic Sensor Science, Nanyang Technological University , 50 Nanyang Drive 637553, Singapore
| | - Bo Liedberg
- School of Materials Science and Engineering, Nanyang Technological University , 50 Nanyang Avenue 639798, Singapore
- Centre for Biomimetic Sensor Science, Nanyang Technological University , 50 Nanyang Drive 637553, Singapore
| | - Atul N Parikh
- School of Materials Science and Engineering, Nanyang Technological University , 50 Nanyang Avenue 639798, Singapore
- Centre for Biomimetic Sensor Science, Nanyang Technological University , 50 Nanyang Drive 637553, Singapore
- Department of Biomedical Engineering and Department of Chemical Engineering and Materials Science, University of California , Davis, California 95616, United States
| | - Nam-Joon Cho
- School of Materials Science and Engineering, Nanyang Technological University , 50 Nanyang Avenue 639798, Singapore
- Centre for Biomimetic Sensor Science, Nanyang Technological University , 50 Nanyang Drive 637553, Singapore
- School of Chemical and Biomedical Engineering, Nanyang Technological University , 62 Nanyang Drive 637459, Singapore
| |
Collapse
|
13
|
Metzler R, Jeon JH, Cherstvy AG. Non-Brownian diffusion in lipid membranes: Experiments and simulations. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1858:2451-2467. [PMID: 26826272 DOI: 10.1016/j.bbamem.2016.01.022] [Citation(s) in RCA: 127] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Revised: 01/21/2016] [Accepted: 01/23/2016] [Indexed: 12/14/2022]
Abstract
The dynamics of constituents and the surface response of cellular membranes-also in connection to the binding of various particles and macromolecules to the membrane-are still a matter of controversy in the membrane biophysics community, particularly with respect to crowded membranes of living biological cells. We here put into perspective recent single particle tracking experiments in the plasma membranes of living cells and supercomputing studies of lipid bilayer model membranes with and without protein crowding. Special emphasis is put on the observation of anomalous, non-Brownian diffusion of both lipid molecules and proteins embedded in the lipid bilayer. While single component, pure lipid bilayers in simulations exhibit only transient anomalous diffusion of lipid molecules on nanosecond time scales, the persistence of anomalous diffusion becomes significantly longer ranged on the addition of disorder-through the addition of cholesterol or proteins-and on passing of the membrane lipids to the gel phase. Concurrently, experiments demonstrate the anomalous diffusion of membrane embedded proteins up to macroscopic time scales in the minute time range. Particular emphasis will be put on the physical character of the anomalous diffusion, in particular, the occurrence of ageing observed in the experiments-the effective diffusivity of the measured particles is a decreasing function of time. Moreover, we present results for the time dependent local scaling exponent of the mean squared displacement of the monitored particles. Recent results finding deviations from the commonly assumed Gaussian diffusion patterns in protein crowded membranes are reported. The properties of the displacement autocorrelation function of the lipid molecules are discussed in the light of their appropriate physical anomalous diffusion models, both for non-crowded and crowded membranes. In the last part of this review we address the upcoming field of membrane distortion by elongated membrane-binding particles. We discuss how membrane compartmentalisation and the particle-membrane binding energy may impact the dynamics and response of lipid membranes. This article is part of a Special Issue entitled: Biosimulations edited by Ilpo Vattulainen and Tomasz Róg.
Collapse
Affiliation(s)
- R Metzler
- Institute for Physics & Astronomy, University of Potsdam, 14476 Potsdam-Golm, Germany; Department of Physics, Tampere University of Technology, 33101 Tampere, Finland.
| | - J-H Jeon
- Korea Institute for Advanced Study (KIAS), Seoul, Republic of Korea
| | - A G Cherstvy
- Institute for Physics & Astronomy, University of Potsdam, 14476 Potsdam-Golm, Germany
| |
Collapse
|
14
|
Sackmann E. How actin/myosin crosstalks guide the adhesion, locomotion and polarization of cells. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2015; 1853:3132-42. [PMID: 26119326 DOI: 10.1016/j.bbamcr.2015.06.012] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2015] [Revised: 06/17/2015] [Accepted: 06/18/2015] [Indexed: 01/09/2023]
Abstract
Cell-tissue-tissue interaction is determined by specific short range forces between cell adhesion molecules (CAMs) and ligands of the tissue, long range repulsion forces mediated by cell surface grafted macromolecules and adhesion-induced elastic stresses in the cell envelope. This interplay of forces triggers the rapid random clustering of tightly coupled linkers. By coupling of actin gel patches to the intracellular domains of the CAMs, these clusters can grow in a secondary process resulting in the formation of functional adhesion microdomains (ADs). The ADs can act as biochemical steering centers by recruiting and activating functional proteins, such as GTPases and associated regulating proteins, through electrostatic-hydrophobic forces with cationic lipid domains that act as attractive centers. First, I summarize physical concepts of cell adhesion revealed by studies of biomimetic systems. Then I describe the role of the adhesion domains as biochemical signaling platforms and force transmission centers promoting cellular protrusions, in terms of a shell string model of cells. Protrusion forces are generated by actin gelation triggered by molecular machines (focal adhesion kinase (FAK), Src-kinases and associated adaptors) which assemble around newly formed integrin clusters. They recruit and activate the GTPases Rac-1 and actin gelation promoters to charged membrane domains via electrostatic-hydrophobic forces. The cell front is pushed forward in a cyclic and stepwise manner and the step-width is determined by the dynamics antagonistic interplay between Rac-1 and RhoA. The global cell polarization in the direction of motion is mediated by the actin-microtubule (MT) crosstalk at adhesion domains. Supramolecular actin-MT assemblies at the front help to promote actin polymerization. At the rear they regulate the dismantling of the ADs through the Ca(++)-mediated activation of the protease calpain and trigger their disruption by RhoA mediated contraction via stress fibers. This article is part of a Special Issue entitled: Mechanobiology.
Collapse
Affiliation(s)
- Erich Sackmann
- Technical University Munich, Germany; Physics Department E22/E27, James Franck Str., D85747 Garching, Germany.
| |
Collapse
|
15
|
Onsager's irreversible thermodynamics of the dynamics of transient pores in spherical lipid vesicles. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2015; 44:473-81. [PMID: 26094069 DOI: 10.1007/s00249-015-1051-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Revised: 03/31/2015] [Accepted: 06/02/2015] [Indexed: 10/23/2022]
Abstract
Onsager's irreversible thermodynamics is used to perform a systematic deduction of the kinetic equations governing the opening and collapse of transient pores in spherical vesicles. We show that the edge tension has to be determined from the initial stage of the pore relaxation and that in the final state the vesicle membrane is not completely relaxed, since the surface tension and the pressure difference are about 25% of its initial value. We also show that the pore life-time is controlled by the solution viscosity and its opening is driven by the solution leak-out and the surface tension drop. The final collapse is due to a non-linear interplay between the edge and the surface tensions together with the pressure difference. We also discuss the connection with previous models.
Collapse
|
16
|
Różycki B, Lipowsky R. Spontaneous curvature of bilayer membranes from molecular simulations: Asymmetric lipid densities and asymmetric adsorption. J Chem Phys 2015; 142:054101. [DOI: 10.1063/1.4906149] [Citation(s) in RCA: 73] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Affiliation(s)
- Bartosz Różycki
- Theory and Biosystems, Max Planck Institute of Colloids and Interfaces, 14424 Potsdam, Germany
- Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warsaw, Poland
| | - Reinhard Lipowsky
- Theory and Biosystems, Max Planck Institute of Colloids and Interfaces, 14424 Potsdam, Germany
| |
Collapse
|
17
|
Fragneto G. Étudier la structure des membranes biologiques : l’intérêt des systèmes modèles et des neutrons. ACTA ACUST UNITED AC 2014. [DOI: 10.1051/refdp/201441036] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
|
18
|
Agarwal R, Iezhitsa I, Agarwal P, Abdul Nasir NA, Razali N, Alyautdin R, Ismail NM. Liposomes in topical ophthalmic drug delivery: an update. Drug Deliv 2014; 23:1075-91. [DOI: 10.3109/10717544.2014.943336] [Citation(s) in RCA: 91] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Affiliation(s)
- Renu Agarwal
- Faculty of Medicine, Universiti Teknologi MARA, Sungai Buloh Campus, Sungai Buloh, Selangor, Malaysia,
- Brain & Neuroscience, Communities of Research (Core), Research Management Institute (RMI), Universiti Teknologi MARA, Shah Alam, Selangor Darul Ehsan, Malaysia,
| | - Igor Iezhitsa
- Faculty of Medicine, Universiti Teknologi MARA, Sungai Buloh Campus, Sungai Buloh, Selangor, Malaysia,
- Brain & Neuroscience, Communities of Research (Core), Research Management Institute (RMI), Universiti Teknologi MARA, Shah Alam, Selangor Darul Ehsan, Malaysia,
- Research Institute of Pharmacology, Volgograd State Medical University, Volgograd, Russian Federation, and
| | - Puneet Agarwal
- Department of Ophthalmology, IMU Clinical School, International Medical University, Jalan Rasah, Seremban, Malaysia
| | - Nurul Alimah Abdul Nasir
- Faculty of Medicine, Universiti Teknologi MARA, Sungai Buloh Campus, Sungai Buloh, Selangor, Malaysia,
- Brain & Neuroscience, Communities of Research (Core), Research Management Institute (RMI), Universiti Teknologi MARA, Shah Alam, Selangor Darul Ehsan, Malaysia,
| | - Norhafiza Razali
- Faculty of Medicine, Universiti Teknologi MARA, Sungai Buloh Campus, Sungai Buloh, Selangor, Malaysia,
- Brain & Neuroscience, Communities of Research (Core), Research Management Institute (RMI), Universiti Teknologi MARA, Shah Alam, Selangor Darul Ehsan, Malaysia,
| | - Renad Alyautdin
- Faculty of Medicine, Universiti Teknologi MARA, Sungai Buloh Campus, Sungai Buloh, Selangor, Malaysia,
| | - Nafeeza Mohd Ismail
- Faculty of Medicine, Universiti Teknologi MARA, Sungai Buloh Campus, Sungai Buloh, Selangor, Malaysia,
- Brain & Neuroscience, Communities of Research (Core), Research Management Institute (RMI), Universiti Teknologi MARA, Shah Alam, Selangor Darul Ehsan, Malaysia,
| |
Collapse
|
19
|
Geislinger TM, Franke T. Hydrodynamic lift of vesicles and red blood cells in flow--from Fåhræus & Lindqvist to microfluidic cell sorting. Adv Colloid Interface Sci 2014; 208:161-76. [PMID: 24674656 DOI: 10.1016/j.cis.2014.03.002] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2014] [Revised: 02/28/2014] [Accepted: 03/02/2014] [Indexed: 12/31/2022]
Abstract
Hydrodynamic lift forces acting on cells and particles in fluid flow receive ongoing attention from medicine, mathematics, physics and engineering. The early findings of Fåhræus & Lindqvist on the viscosity change of blood with the diameter of capillaries motivated extensive studies both experimentally and theoretically to illuminate the underlying physics. We review this historical development that led to the discovery of the inertial and non-inertial lift forces and elucidate the origins of these forces that are still not entirely clear. Exploiting microfluidic techniques induced a tremendous amount of new insights especially into the more complex interactions between the flow field and deformable objects like vesicles or red blood cells. We trace the way from the investigation of single cell dynamics to the recent developments of microfluidic techniques for particle and cell sorting using hydrodynamic forces. Such continuous and label-free on-chip cell sorting devices promise to revolutionize medical analyses for personalized point-of-care diagnosis. We present the state-of-the-art of different hydrodynamic lift-based techniques and discuss their advantages and limitations.
Collapse
|
20
|
Rinaudo M, Quemeneur F, Dubreuil F, Fery A, Pépin-Donat B. Mechanical Characterization of Micrometric Chitosan-Coated Vesicle by Atomic Force Microscopy. INTERNATIONAL JOURNAL OF POLYMER ANALYSIS AND CHARACTERIZATION 2013. [DOI: 10.1080/1023666x.2013.842352] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
|
21
|
Benhamou M, Kaidi H. Unbinding transition from fluid membranes with associated polymers. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2013; 36:125. [PMID: 24162525 DOI: 10.1140/epje/i2013-13125-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2013] [Revised: 07/06/2013] [Accepted: 10/09/2013] [Indexed: 06/02/2023]
Abstract
We consider two neighboring fluid membranes that are associated with long flexible polymers (proteins or other macromolecules). We are interested in two physical systems consisting of i) two adjacent membranes with end-grafted (or adsorbed) polymers (system I), or ii) two membranes confining a polymer solution (system II). In addition to the pure interactions between membranes, the presence of polymers gives rise to new induced mediated interactions, which are repulsive, for system I, and attractive, for system II. In fact, repulsive induced interactions are caused by the excluded-volume forces between grafted polymers, while attractive ones, by entropy loss, due to free motion of polymers between membranes. The main goal is a quantitative study of the unbinding transition thermodynamics that is drastically affected by the associated polymers. For system I, the repulsive polymer-mediated force delays this transition that can happen at low temperature. To investigate the unbinding phenomenon, we first present an exact mathematical analysis of the total potential that is the sum of the primitive and induced potentials. This mathematical study enables us to classify the total interaction potentials, in terms of all parameters of the problem. Second, use is made of the standard variational method to calculate the first moments of the membrane separation. Special attention is paid to the determination of the unbinding temperature. In particular, we discuss its dependence on the extra parameters related to the associated polymers, which are the surface coverage and the polymer layer thickness on each membrane (for system I) or the polymer density and the gyration radius of coils (for system II). Third, we compute the disjoining pressure upon membrane separation. Finally, we emphasize that the presence of polymers may be a mechanism to delay or to accentuate the appearance of the unbinding transition between fluid membranes.
Collapse
Affiliation(s)
- M Benhamou
- ENSAM, Moulay Ismail University, P.O. Box 25290, Al Mansour, Meknes, Morocco,
| | | |
Collapse
|
22
|
Abstract
We review recent computer simulation studies of undulating lipid bilayers. Theoretical interpretations of such fluctuating membranes are most commonly based on generalized Helfrich-type elastic models, with additional contributions of local "protrusions" and/or density fluctuations. Such models provide an excellent basis for describing the fluctuations of tensionless bilayers in the fluid Lαphase at a quantitative level.However, this description is found to fail for membranes in the gel phase and for membranes subject to high tensions. The fluctuations of tilted gel membranes (Lβ′phase) show a signature of the modulated ripple structure Pβ′, which is a nearby phase observed in the pretransition regime between the Lαand Lβ′state. This complicates a quantitative analysis on mesoscopic length scales. In the case of fluid membranes under tension, the large-wavelength fluctuation modes are found to be significantly softer than predicted by theory.In the latter context, we also address the general problem of the relation between frame tension and the fluctuation tension, which has been discussed somewhat controversially in recent years. Simulations of very simple model membranes with fixed area show that the fluctuations should be controlled by the frame tension, and not by the internal tension.
Collapse
Affiliation(s)
- FRIEDERIKE SCHMID
- Institute of Physics, Johannes-Gutenberg University of Mainz, D-55099 Mainz, Germany
| |
Collapse
|
23
|
Yuan Z, Qin M, Chen X, Liu C, Li H, Hao J. Phase behavior, rheological property, and transmutation of vesicles in fluorocarbon and hydrocarbon surfactant mixtures. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:9355-9364. [PMID: 22646993 DOI: 10.1021/la301416e] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We present a detailed study of a salt-free cationic/anionic (catanionic) surfactant system where a strongly alkaline cationic surfactant (tetradecyltrimethylammonium hydroxide, TTAOH) was mixed with a single-chain fluorocarbon acid (nonadecafluorodecanoic acid, NFDA) and a hyperbranched hydrocarbon acid [di-(2-ethylhexyl)phosphoric acid, DEHPA] in water. Typically the concentration of TTAOH is fixed while the total concentration and mixing molar ratio of NFDA and DEHPA is varied. In the absence of DEHPA and at a TTAOH concentration of 80 mmol·L(-1), an isotropic L(1) phase, an L(1)/L(α) two-phase region, and a single L(α) phase were observed successively with increasing mixing molar ratio of NFDA to TTAOH (n(NFDA)/n(TTAOH)). In the NFDA-rich region (n(NFDA)/n(TTAOH) > 1), a small amount of excess NFDA can be solubilized into the L(α) phase while a large excess of NFDA eventually leads to phase separation. When NFDA is replaced gradually by DEHPA, the mixed system of TTAOH/NFDA/DEHPA/H(2)O follows the same phase sequence as that of the TTAOH/NFDA/H(2)O system and the phase boundaries remain almost unchanged. However, the viscoelasticity of the samples in the single L(α) phase region becomes higher at the same total surfactant concentration as characterized by rheological measurements. Cryo-transmission electron microscopic (cryo-TEM) observations revealed a microstructural evolution from unilamellar vesicles to multilamellar ones and finally to gaint onions. The size of the vesicle and number of lamella can be controlled by adjusting the molar ratio of NFDA to DEHPA. The dynamic properties of the vesicular solutions have also been investigated. It is found that the yield stress and the storage modulus are time-dependent after a static mixing process between the two different types of vesicle solutions, indicating the occurrence of a dynamic fusion between the two types of vesicles. The microenvironmental changes induced by aggregate transitions were probed by (19)F NMR as well as (31)P NMR measurements. Upon replacement of NFDA by DEHPA, the signal from the (19)F atoms adjacent to the hydrophilic headgroup disappears and that from the (19)F atoms on the main chain becomes sharper. This could be interpreted as an increase of microfluidity in the mixed vesicle bilayers at higher content of DEHPA, whose alkyl chains are expected to have a lower chain melting point. Our results provide basic knowledge on vesicle formation and their structural evolution in salt-free catanionic surfactant systems containing mixed ion pairs, which may contribute to a deeper understanding of the rules governing the formation and properties of surfactant self-assembly.
Collapse
Affiliation(s)
- Zaiwu Yuan
- School of Chemistry and Pharmaceutical Engineering, Shandong Polytechnic University, Jinan 250353, People's Republic of China
| | | | | | | | | | | |
Collapse
|
24
|
Speck T, Reister E, Seifert U. Specific adhesion of membranes: Mapping to an effective bond lattice gas. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2010; 82:021923. [PMID: 20866853 DOI: 10.1103/physreve.82.021923] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2010] [Revised: 06/07/2010] [Indexed: 05/29/2023]
Abstract
We theoretically consider specific adhesion of a fluctuating membrane to a hard substrate via the formation of bonds between receptors attached to the substrate and ligands in the membrane. By integrating out the degrees of freedom of the membrane shape, we show that in the biologically relevant limit specific adhesion is well described by a lattice gas model, where lattice sites correspond to bond sites. We derive an explicit expression for the effective bond interactions induced by the thermal undulations of the membrane. Furthermore, we compare kinetic Monte Carlo simulations for our lattice gas model with full dynamic simulations that take into account both the shape fluctuations of the membrane and reactions between receptors and ligands at bond sites. We demonstrate that an appropriate mapping of the height dependent binding and unbinding rates in the full scheme to rates in the lattice gas model leads to good agreement.
Collapse
Affiliation(s)
- Thomas Speck
- Department of Chemistry, University of California, Berkeley, 94720, USA
| | | | | |
Collapse
|
25
|
Smirnova YG, Marrink SJ, Lipowsky R, Knecht V. Solvent-Exposed Tails as Prestalk Transition States for Membrane Fusion at Low Hydration. J Am Chem Soc 2010; 132:6710-8. [DOI: 10.1021/ja910050x] [Citation(s) in RCA: 128] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Yuliya G. Smirnova
- Max-Planck Institute of Colloids and Interfaces, Department of Theory and Bio-Systems, Research Campus Golm, D-14424 Potsdam, Germany, and Groningen Biomolecular Sciences and Biotechnology Institute & Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Siewert-Jan Marrink
- Max-Planck Institute of Colloids and Interfaces, Department of Theory and Bio-Systems, Research Campus Golm, D-14424 Potsdam, Germany, and Groningen Biomolecular Sciences and Biotechnology Institute & Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Reinhard Lipowsky
- Max-Planck Institute of Colloids and Interfaces, Department of Theory and Bio-Systems, Research Campus Golm, D-14424 Potsdam, Germany, and Groningen Biomolecular Sciences and Biotechnology Institute & Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Volker Knecht
- Max-Planck Institute of Colloids and Interfaces, Department of Theory and Bio-Systems, Research Campus Golm, D-14424 Potsdam, Germany, and Groningen Biomolecular Sciences and Biotechnology Institute & Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| |
Collapse
|
26
|
Malaquin L, Charitat T, Daillant J. Supported bilayers: combined specular and diffuse X-ray scattering. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2010; 31:285-301. [PMID: 20306279 DOI: 10.1140/epje/i2010-10578-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2009] [Accepted: 02/03/2010] [Indexed: 05/29/2023]
Abstract
A method is proposed for the analysis of specular and off-specular reflectivity from supported lipid bilayers. Both thermal fluctuations and the "static" roughness induced by the substrate are carefully taken into account. Examples from supported bilayers and more complex systems comprising a bilayer adsorbed or grafted on the substrate and another "floating" bilayer are given. The combined analysis of specular and off-specular reflectivity allows the precise determination of the structure of adsorbed and floating bilayers, their tension, bending rigidity and interaction potentials. We show that this new method gives a unique opportunity to investigate phenomena like protrusion modes of adsorbed bilayers and opens the way to the investigation of more complex systems including different kinds of lipids, cholesterol or peptides.
Collapse
Affiliation(s)
- L Malaquin
- Institut Charles Sadron, Université de Strasbourg, CNRS UPR 22, 23 Rue du Loess, BP 84047, 67034, Strasbourg cedex 2, France
| | | | | |
Collapse
|
27
|
Grafmüller A, Shillcock J, Lipowsky R. The fusion of membranes and vesicles: pathway and energy barriers from dissipative particle dynamics. Biophys J 2009; 96:2658-75. [PMID: 19348749 PMCID: PMC2711276 DOI: 10.1016/j.bpj.2008.11.073] [Citation(s) in RCA: 116] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2008] [Revised: 11/14/2008] [Accepted: 11/19/2008] [Indexed: 10/20/2022] Open
Abstract
The fusion of lipid bilayers is studied with dissipative particle dynamics simulations. First, to achieve control over membrane properties, the effects of individual simulation parameters are studied and optimized. Then, a large number of fusion events for a vesicle and a planar bilayer are simulated using the optimized parameter set. In the observed fusion pathway, configurations of individual lipids play an important role. Fusion starts with individual lipids assuming a splayed tail configuration with one tail inserted in each membrane. To determine the corresponding energy barrier, we measure the average work for interbilayer flips of a lipid tail, i.e., the average work to displace one lipid tail from one bilayer to the other. This energy barrier is found to depend strongly on a certain dissipative particle dynamics parameter, and, thus, can be adjusted in the simulations. Overall, three subprocesses have been identified in the fusion pathway. Their energy barriers are estimated to lie in the range 8-15 k(B)T. The fusion probability is found to possess a maximum at intermediate tension values. As one decreases the tension, the fusion probability seems to vanish before the tensionless membrane state is attained. This would imply that the tension has to exceed a certain threshold value to induce fusion.
Collapse
Affiliation(s)
- Andrea Grafmüller
- Theory and Bio-Systems, Max Planck Institute for Colloids and Interfaces, Potsdam, Germany.
| | | | | |
Collapse
|
28
|
Abstract
Cell membranes are studded with protrusions that were thoroughly analyzed with electron microscopy. However, the nanometer-scale three-dimensional motions generated by cell membranes to fit the topography of foreign surfaces and initiate adhesion remain poorly understood. Here, we describe the dynamics of surface deformations displayed by monocytic cells bumping against fibronectin-coated surfaces. We observed membrane undulations with typically 5 nm amplitude and 5-10 s lifetime. Cell membranes behaved as independent units of micrometer size. Cells detected the presence of foreign surfaces at 50 nm separation, resulting in time-dependent amplification of membrane undulations. Molecular contact then ensued with apparent cell-membrane separation of 30-40 nm, and this distance steadily decreased during the following tens of seconds. Contact maturation was associated with in-plane egress of bulky molecules and robust membrane fluctuations. Thus, membrane undulations may be the major determinant of cell sensitivity to substrate topography, outcome of interaction, and initial kinetics of contact extension.
Collapse
|
29
|
Pabst G, Hodzic A, Strancar J, Danner S, Rappolt M, Laggner P. Rigidification of neutral lipid bilayers in the presence of salts. Biophys J 2007; 93:2688-96. [PMID: 17586572 PMCID: PMC1989724 DOI: 10.1529/biophysj.107.112615] [Citation(s) in RCA: 178] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We studied the influence of sodium and calcium chloride on the global and local membrane properties of fluid palmitoyl-oleoyl phosphatidylcholine bilayers, applying synchrotron small-angle x-ray diffraction, spin-labeling electron paramagnetic resonance spectroscopy, and differential scanning calorimetry, as well as simultaneous density and acoustic measurements. The salt concentration was varied over a wide range from 0 to 5 M. We found that NaCl leads to a continuous swelling of the bilayers, whereas the behavior of the bilayer separation dW in the presence of CaCl2 is more complex, showing an initial large dW value, which decreased upon further addition of salt and finally increased again in the high concentration regime. This can be understood by a change of balance between electrostatic and van der Waals interactions. We were further able to show that both salts lead to a significant increase of order within the lipid bilayer, leading to a decrease of bilayer elasticity and shift of main phase transition temperature. This effect is more pronounced for Ca2+, and occurs mainly in the high salt-concentration regime. Thus, we were able to reconcile previous controversies between molecular dynamics simulations and x-ray diffraction experiments regarding the effect of salts on neutral lipid bilayers.
Collapse
Affiliation(s)
- Georg Pabst
- Institute of Biophysics and Nanosystems Research, Austrian Academy of Sciences, Graz, Austria.
| | | | | | | | | | | |
Collapse
|
30
|
Mouritsen OG, Andresen TL, Halperin A, Hansen PL, Jakobsen AF, Jensen UB, Jensen MO, Jørgensen K, Kaasgaard T, Leidy C, Simonsen AC, Peters GH, Weiss M. Activation of interfacial enzymes at membrane surfaces. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2006; 18:S1293-S1304. [PMID: 21690842 DOI: 10.1088/0953-8984/18/28/s12] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
A host of water-soluble enzymes are active at membrane surfaces and in association with membranes. Some of these enzymes are involved in signalling and in modification and remodelling of the membranes. A special class of enzymes, the phospholipases, and in particular secretory phospholipase A(2) (sPLA(2)), are only activated at the interface between water and membrane surfaces, where they lead to a break-down of the lipid molecules into lysolipids and free fatty acids. The activation is critically dependent on the physical properties of the lipid-membrane substrate. A topical review is given of our current understanding of the physical mechanisms responsible for activation of sPLA(2) as derived from a range of different experimental and theoretical investigations.
Collapse
Affiliation(s)
- Ole G Mouritsen
- MEMPHYS-Center for Biomembrane Physics, Physics Department, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
31
|
Mennicke U, Constantin D, Salditt T. Structure and interaction potentials in solid-supported lipid membranes studied by X-ray reflectivity at varied osmotic pressure. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2006; 20:221-30. [PMID: 16802069 DOI: 10.1140/epje/i2006-10014-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2006] [Accepted: 05/26/2006] [Indexed: 05/10/2023]
Abstract
Highly oriented solid-supported lipid membranes in stacks of controlled number N approximately 16 (oligo-membranes) have been prepared by spin-coating using the uncharged lipid model system 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC). The samples have been immersed in aqueous polymer solutions for control of osmotic pressure and have been studied by X-ray reflectivity. The bilayer structure and fluctuations have been determined by modelling the data over the full q-range. Thermal fluctuations are described using the continuous smectic Hamiltonian with the appropriate boundary conditions at the substrate and at the free surface of the stack. The resulting fluctuation amplitudes and the pressure-distance relation are discussed in view of the inter-bilayer potential.
Collapse
Affiliation(s)
- U Mennicke
- Institut für Röntgenphysik, Friedrich-Hund-Platz 1, 37077, Göttingen, Germany.
| | | | | |
Collapse
|
32
|
Komura S, Shimokawa N, Kato T. Unbinding and preunbinding in surfactant solutions. J Chem Phys 2006; 124:034906. [PMID: 16438613 DOI: 10.1063/1.2159475] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
We propose models for the first-order unbinding transition of lyotropic lamellae in surfactant solutions. The coupling between the surfactant volume fraction and the elastic degree of freedom is considered so that the net attractive interaction between the surfactant molecules is enhanced. The elastic degree of freedom can be either (i) a membrane elastic degree of freedom or (ii) a bulk elastic degree of freedom. The phase behaviors of these two models are analyzed. For both cases, the unbinding transition becomes first order when the coupling is strong enough. We determine the associated preunbinding line which separates two lamellar phases having different repeat distances.
Collapse
Affiliation(s)
- S Komura
- Department of Chemistry, Faculty of Science, Tokyo Metropolitan University, Tokyo 192-0397, Japan.
| | | | | |
Collapse
|
33
|
Weikl TR, Lipowsky R. Chapter 4 Membrane Adhesion and Domain Formation. ADVANCES IN PLANAR LIPID BILAYERS AND LIPOSOMES 2006. [DOI: 10.1016/s1554-4516(06)05004-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
|
34
|
Halperin A, Mouritsen OG. Role of lipid protrusions in the function of interfacial enzymes. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2005; 34:967-71. [PMID: 15883844 DOI: 10.1007/s00249-005-0466-z] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2004] [Revised: 12/22/2004] [Accepted: 12/22/2004] [Indexed: 11/28/2022]
Abstract
Secretory phospholipase A(2) (sPLA(2)) is a class of interfacially active enzymes that selectively hydrolyze lipid molecules organized at interfaces like membranes. We present a simple theoretical model that relates the sPLA(2) action to the protrusions of the lipid molecules. The model explains (1) the observed enhancement of enzymatic activity by lipids with flexible, neutral, water-soluble polymers linked to their head groups and (2) the lag-burst kinetics of sPLA(2). It yields qualitative predictions of the effect of the initial composition of the membrane, the molecular weight of the polymer, and the composition of the hydrolysis products.
Collapse
Affiliation(s)
- Avi Halperin
- UMR 5819, DRFMC/SI3M, CEA-CENG, 17 Rue des Martyrs, 38054 Grenoble Cedex 9, France
| | | |
Collapse
|
35
|
Majhenc J, Bozic B, Svetina S, Zeks B. Phospholipid membrane bending as assessed by the shape sequence of giant oblate phospholipid vesicles. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2004; 1664:257-66. [PMID: 15328058 DOI: 10.1016/j.bbamem.2004.06.006] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2003] [Revised: 06/08/2004] [Accepted: 06/15/2004] [Indexed: 11/26/2022]
Abstract
Vesicle shape transformations caused by decreasing the difference between the equilibrium areas of membrane monolayers were studied on phospholipid vesicles with small volume to membrane area ratios. Slow transformations of the vesicle shape were induced by lowering of the concentration of lipid monomers in the solution outside the vesicle. The complete sequence of shapes consisted of a string of pearls, and wormlike, starfish, discocyte and stomatocyte shapes. The transformation from discocyte to stomatocyte vesicle shapes was analyzed theoretically to see whether these observations accord with the area difference elasticity (ADE) model. The membrane shape equation and boundary conditions were derived for axisymmetrical shapes for low volume vesicles, part of whose membranes are in contact. Calculated shapes were arranged into a phase diagram. The theory predicts that the transition between discocyte and stomatocyte shapes is discontinuous for relatively high volumes and continuous for low volumes. The calculated shape sequences matched well with the observed ones. By assuming a linear decrease of the equilibrium area difference with time, the ratio between the nonlocal and local bending constants is in agreement with reported values.
Collapse
Affiliation(s)
- J Majhenc
- Institute of Biophysics, Faculty of Medicine, University of Ljubljana, Lipiceva 2, SI-1000, Slovenia.
| | | | | | | |
Collapse
|
36
|
Dogic Z. Surface freezing and a two-step pathway of the isotropic-smectic phase transition in colloidal rods. PHYSICAL REVIEW LETTERS 2003; 91:165701. [PMID: 14611416 DOI: 10.1103/physrevlett.91.165701] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2003] [Indexed: 05/24/2023]
Abstract
We study the kinetics of the isotropic-smectic phase transition in a colloidal rod/polymer mixture by visualizing individual smectic layers. First, we show that the bulk isotropic-smectic phase transition is preceded by a surface freezing transition in which a quasi-two-dimensional smectic phase wets the isotropic-nematic interface. Next, we identify a two-step kinetic pathway for the formation of a bulk smectic phase. In the first step a metastable isotropic-nematic interface is formed. This interface is wetted by the surface-induced smectic phase. In the subsequent step, smectic layers nucleate at this surface phase and grow into the isotropic bulk phase.
Collapse
Affiliation(s)
- Zvonimir Dogic
- IFF/Weiche Materie, Forschungszentrum Jülich, Jülich, D-52425 Germany
| |
Collapse
|
37
|
Mavromoustakos T, Papahatjis D, Laggner P. Differential membrane fluidization by active and inactive cannabinoid analogues. BIOCHIMICA ET BIOPHYSICA ACTA 2001; 1512:183-90. [PMID: 11406095 DOI: 10.1016/s0005-2736(01)00315-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
The effects of the two cannabinomimetic drugs (-)-2-(6a,7,10,10a-tetrahydro-6,6,9-trimethyl-1-hydroxy-6H-dibenzo[b,d]pyranyl-2-(hexyl)-1,3-dithiolane (AMG-3) and its pharmacologically less active 1-methoxy analogue (AMG-18) on the thermotropic and structural properties of dipalmitoyl-sn-glycero-3-phosphorylcholine (DPPC) liposomes have been studied by X-ray diffraction and differential scanning calorimetry (DSC). DSC data revealed that the incorporation of the drugs affect differently the thermotropic properties of DPPC. The presence of the more active drug distinctly broadened and attenuated both the pretransition and main phase transition of DPPC bilayers, while the inactive analogue had only minor effects. Small and wide angle X-ray diffraction data showed that the two cannabinoids have different effects on the lipid phase structures and on the hydrocarbon chain packing. The pharmacologically active analogue, AMG-3, was found to efficiently fluidize domains of the lipids in the L(beta)' gel phase, and to perturb the regular multibilayer lattice. In the liquid crystalline L(alpha) phase, AMG-3 was also found to cause irregularities in packing, suggesting that the drug induces local curvature. At the same concentration, the inactive AMG-18 had only minor structural effects on the lipids. At about 10-fold or higher concentrations, AMG-18 was found to produce similar but still less pronounced effects in comparison to those observed by AMG-3. The dose-dependent, different thermotropic and structural effects by the two cannabinoid analogues suggest that these may be related to their biological activity.
Collapse
Affiliation(s)
- T Mavromoustakos
- Institute of Organic and Pharmaceutical Chemistry, National Hellenic Research Foundation, Athens, Greece.
| | | | | |
Collapse
|
38
|
Kloboucek A, Behrisch A, Faix J, Sackmann E. Adhesion-induced receptor segregation and adhesion plaque formation: A model membrane study. Biophys J 1999; 77:2311-28. [PMID: 10512849 PMCID: PMC1300510 DOI: 10.1016/s0006-3495(99)77070-0] [Citation(s) in RCA: 116] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
A model system to study the control of cell adhesion by receptor-mediated specific forces, universal interactions, and membrane elasticity is established. The plasma membrane is mimicked by reconstitution of homophilic receptor proteins into solid supported membranes and, together with lipopolymers, into giant vesicles with the polymers forming an artificial glycocalix. The homophilic cell adhesion molecule contact site A, a lipid-anchored glycoprotein from cells of the slime mold Dictyostelium discoideum, is used as receptor. The success of the reconstitution, the structure and the dynamics of the model membranes are studied by various techniques including film balance techniques, micro fluorescence, fluorescence recovery after photobleaching, electron microscopy, and phase contrast microscopy. The interaction of the functionalized giant vesicles with the supported bilayer is studied by reflection interference contrast microscopy, and the adhesion strength is evaluated quantitatively by a recently developed technique. At low receptor concentrations adhesion-induced receptor segregation in the membranes leads to decomposition of the contact zone between membranes into domains of strong (receptor-mediated) adhesion and regions of weak adhesion while continuous zones of strong adhesion form at high receptor densities. The adhesion strengths (measured in terms of the spreading pressure S) of the various states of adhesion are obtained locally by analysis of the vesicle contour near the contact line in terms of elastic boundary conditions of adhesion: the balance of tensions and moments. The spreading pressure of the weak adhesion zones is S approximately 10(-9) J/m(2) and is determined by the interplay of gravitation and undulation forces whereas the spreading pressure of the tight adhesion domains is of the order S approximately 10(-6) J/m(2).
Collapse
Affiliation(s)
- A Kloboucek
- Physik Department, E22 (Biophysical Laboratory), Technische Universität München, James-Franck-Strasse, D-85747 Garching, Germany
| | | | | | | |
Collapse
|
39
|
Seifert U. Fluid bilayer vesicles Statistical physics of soft two-dimensional surfaces. LIQUID CRYSTALS TODAY 1997. [DOI: 10.1080/13583149708047666] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
|