1
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Plotnikov D, Ahn SH. Optimization of the resampling method in the weighted ensemble simulation toolkit with parallelization and analysis (WESTPA). J Chem Phys 2024; 161:046101. [PMID: 39037142 DOI: 10.1063/5.0197141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2024] [Accepted: 07/09/2024] [Indexed: 07/23/2024] Open
Affiliation(s)
- Dennis Plotnikov
- Department of Chemical Engineering, University of California, Davis, Davis, California 95616, USA
| | - Surl-Hee Ahn
- Department of Chemical Engineering, University of California, Davis, Davis, California 95616, USA
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2
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Li L, Ji J, Song F, Hu J. Intercellular Receptor-ligand Binding: Effect of Protein-membrane Interaction. J Mol Biol 2023; 435:167787. [PMID: 35952805 DOI: 10.1016/j.jmb.2022.167787] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 08/03/2022] [Accepted: 08/04/2022] [Indexed: 02/04/2023]
Abstract
Gaining insights into the intercellular receptor-ligand binding is of great importance for understanding numerous physiological and pathological processes, and stimulating new strategies in drug design and discovery. In contrast to the in vitro protein interaction in solution, the anchored receptor and ligand molecules interact with membrane in situ, which affects the intercellular receptor-ligand binding. Here, we review theoretical, simulation and experimental works regarding the regulatory effects of protein-membrane interactions on intercellular receptor-ligand binding mainly from the following aspects: membrane fluctuations, membrane curvature, glycocalyx, and lipid raft. In addition, we discuss biomedical significances and possible research directions to advance the field and highlight the importance of understanding of coupling effects of these factors in pharmaceutical development.
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Affiliation(s)
- Long Li
- Kuang Yaming Honors School and Institute for Brain Sciences, Nanjing University, 210023 Nanjing, China; State Key Laboratory of Nonlinear Mechanics and Beijing Key Laboratory of Engineered Construction and Mechanobiology, Institute of Mechanics, Chinese Academy of Sciences, 100190 Beijing, China
| | - Jing Ji
- Key Laboratory of Biomechanics and Mechanobiology (Beihang University), Ministry of Education Beijing Advanced Innovation Center for Biomedical Engineering School of Biological Science and Medical Engineering, Beihang University, Beijing 100083, China.
| | - Fan Song
- State Key Laboratory of Nonlinear Mechanics and Beijing Key Laboratory of Engineered Construction and Mechanobiology, Institute of Mechanics, Chinese Academy of Sciences, 100190 Beijing, China; School of Engineering Science, University of Chinese Academy of Sciences, 100049 Beijing, China
| | - Jinglei Hu
- Kuang Yaming Honors School and Institute for Brain Sciences, Nanjing University, 210023 Nanjing, China.
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3
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Pandey PR, Rózycki B, Weikl TR. Molecular Dynamics Simulations of Immune Receptors and Ligands. Methods Mol Biol 2023; 2654:51-59. [PMID: 37106175 DOI: 10.1007/978-1-0716-3135-5_4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/29/2023]
Abstract
Molecular dynamics simulations of immune receptor and ligand proteins in their native membrane environment allow to determine the orientational and structural variability of the proteins and protein complexes. The simulations complement the static, "membrane-free" structural information obtained from cryo-EM structures of transmembrane proteins in detergent micelles or from crystal structures of extracellular protein domains. Here we describe how to set up and perform simulations of transmembrane receptors, ligands, and receptor-ligand complexes.
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Affiliation(s)
- Prithvi R Pandey
- Max Planck Institute of Colloids and Interfaces, Potsdam, Germany
| | - Bartosz Rózycki
- Institute of Physics of the Polish Academy of Sciences, Warszawa, Poland
| | - Thomas R Weikl
- Max Planck Institute of Colloids and Interfaces, Potsdam, Germany.
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4
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Li L, Hu J, Różycki B, Ji J, Song F. Interplay of receptor-ligand binding and lipid domain formation during cell adhesion. Front Mol Biosci 2022; 9:1019477. [PMID: 36203878 PMCID: PMC9531914 DOI: 10.3389/fmolb.2022.1019477] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Accepted: 09/05/2022] [Indexed: 11/20/2022] Open
Abstract
Cell adhesion involved in biological processes such as cell migration, immune responses, and cancer metastasis, is mediated by the specific binding of receptor and ligand proteins. Some of these proteins exhibit affinity for nanoscale lipid clusters in cell membranes. A key question is how these nanoscale lipid clusters influence and react to the receptor-ligand binding during cell adhesion. In this article, we review recent computational studies that shed new light on the interplay of the receptor-ligand binding and the formation of lipid domains in adhering membranes. These studies indicate that the receptor-ligand binding promotes coalescence of lipid clusters into mesoscale domains, which, in turn, enhances both the affinity and cooperativity of the receptor-ligand binding in cell-cell adhesion with mobile ligands. In contrast, in the case of cell-extracellular matrix adhesion with immobile ligands, the receptor-ligand binding and the lipid cluster coalescence can be correlated or anti-correlated, depending strongly on the ligand distribution. These findings deepen our understanding of correlations between cell adhesion and membrane heterogeneities.
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Affiliation(s)
- Long Li
- Kuang Yaming Honors School and Institute for Brain Sciences, Nanjing University, Nanjing, China
- State Key Laboratory of Nonlinear Mechanics and Beijing Key Laboratory of Engineered Construction and Mechanobiology, Institute of Mechanics, Chinese Academy of Sciences, Beijing, China
| | - Jinglei Hu
- Kuang Yaming Honors School and Institute for Brain Sciences, Nanjing University, Nanjing, China
- *Correspondence: Jinglei Hu, ; Bartosz Różycki, ; Jing Ji,
| | - Bartosz Różycki
- Institute of Physics, Polish Academy of Sciences, Warsaw, Poland
- *Correspondence: Jinglei Hu, ; Bartosz Różycki, ; Jing Ji,
| | - Jing Ji
- Key Laboratory of Biomechanics and Mechanobiology (Beihang University), Ministry of Education Beijing Advanced Innovation Center for Biomedical Engineering School of Biological Science and Medical Engineering, Beihang University, Beijing, China
- *Correspondence: Jinglei Hu, ; Bartosz Różycki, ; Jing Ji,
| | - Fan Song
- State Key Laboratory of Nonlinear Mechanics and Beijing Key Laboratory of Engineered Construction and Mechanobiology, Institute of Mechanics, Chinese Academy of Sciences, Beijing, China
- School of Engineering Science, University of Chinese Academy of Sciences, Beijing, China
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5
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An C, Wang X, Song F, Hu J, Li L. Insights into intercellular receptor-ligand binding kinetics in cell communication. Front Bioeng Biotechnol 2022; 10:953353. [PMID: 35837553 PMCID: PMC9273785 DOI: 10.3389/fbioe.2022.953353] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Accepted: 06/09/2022] [Indexed: 01/14/2023] Open
Abstract
Cell-cell communication is crucial for cells to sense, respond and adapt to environmental cues and stimuli. The intercellular communication process, which involves multiple length scales, is mediated by the specific binding of membrane-anchored receptors and ligands. Gaining insight into two-dimensional receptor-ligand binding kinetics is of great significance for understanding numerous physiological and pathological processes, and stimulating new strategies in drug design and discovery. To this end, extensive studies have been performed to illuminate the underlying mechanisms that control intercellular receptor-ligand binding kinetics via experiment, theoretical analysis and numerical simulation. It has been well established that the cellular microenvironment where the receptor-ligand interaction occurs plays a vital role. In this review, we focus on the advances regarding the regulatory effects of three factors including 1) protein-membrane interaction, 2) biomechanical force, and 3) bioelectric microenvironment to summarize the relevant experimental observations, underlying mechanisms, as well as their biomedical significances and applications. Meanwhile, we introduce modeling methods together with experiment technologies developed for dealing with issues at different scales. We also outline future directions to advance the field and highlight that building up systematic understandings for the coupling effects of these regulatory factors can greatly help pharmaceutical development.
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Affiliation(s)
- Chenyi An
- School of Biology and Engineering, Guizhou Medical University, Guiyang, China
- Department of Cell Biology and Department of Cardiology of the Second Affiliated Hospital, Zhejiang University School of Medicine, Zhejiang University, Hangzhou, China
| | - Xiaohuan Wang
- Department of Rehabilitation Medicine, Peking University Third Hospital, Beijing, China
| | - Fan Song
- State Key Laboratory of Nonlinear Mechanics and Beijing Key Laboratory of Engineered Construction and Mechanobiology, Institute of Mechanics, Chinese Academy of Sciences, Beijing, China
- School of Engineering Science, University of Chinese Academy of Sciences, Beijing, China
| | - Jinglei Hu
- Kuang Yaming Honors School and Institute for Brain Sciences, Nanjing University, Nanjing, China
- *Correspondence: Jinglei Hu, ; Long Li,
| | - Long Li
- State Key Laboratory of Nonlinear Mechanics and Beijing Key Laboratory of Engineered Construction and Mechanobiology, Institute of Mechanics, Chinese Academy of Sciences, Beijing, China
- *Correspondence: Jinglei Hu, ; Long Li,
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6
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Kaurin D, Bal PK, Arroyo M. Peeling dynamics of fluid membranes bridged by molecular bonds: moving or breaking. JOURNAL OF THE ROYAL SOCIETY, INTERFACE 2022; 19:20220183. [PMID: 35765808 PMCID: PMC9240675 DOI: 10.1098/rsif.2022.0183] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Biological adhesion is a critical mechanical function of complex organisms. At the scale of cell–cell contacts, adhesion is remarkably tunable to enable both cohesion and malleability during development, homeostasis and disease. It is physically supported by transient and laterally mobile molecular bonds embedded in fluid membranes. Thus, unlike specific adhesion at solid–solid or solid–fluid interfaces, peeling at fluid–fluid interfaces can proceed by breaking bonds, by moving bonds or by a combination of both. How the additional degree of freedom provided by bond mobility changes the mechanics of peeling is not understood. To address this, we develop a theoretical model coupling diffusion, reactions and mechanics. Mobility and reaction rates determine distinct peeling regimes. In a diffusion-dominated Stefan-like regime, bond motion establishes self-stabilizing dynamics that increase the effective fracture energy. In a reaction-dominated regime, peeling proceeds by travelling fronts where marginal diffusion and unbinding control peeling speed. In a mixed reaction–diffusion regime, strengthening by bond motion competes with weakening by bond breaking in a force-dependent manner, defining the strength of the adhesion patch. In turn, patch strength depends on molecular properties such as bond stiffness, force sensitivity or crowding. We thus establish the physical rules enabling tunable cohesion in cellular tissues and in engineered biomimetic systems.
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Affiliation(s)
- Dimitri Kaurin
- Universitat Politècnica de Catalunya-BarcelonaTech, 08034 Barcelona, Spain
| | - Pradeep K Bal
- Universitat Politècnica de Catalunya-BarcelonaTech, 08034 Barcelona, Spain
| | - Marino Arroyo
- Universitat Politècnica de Catalunya-BarcelonaTech, 08034 Barcelona, Spain.,Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology, 08034 Barcelona, Spain.,CIMNE, 08034 Barcelona, Spain
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7
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Gao J, Hou R, Li L, Hu J. Membrane-Mediated Interactions Between Protein Inclusions. Front Mol Biosci 2021; 8:811711. [PMID: 35004858 PMCID: PMC8727768 DOI: 10.3389/fmolb.2021.811711] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Accepted: 11/30/2021] [Indexed: 11/13/2022] Open
Abstract
Integral or peripheral membrane proteins, or protein oligomers often get close to each other on cell membranes and carry out biological tasks in a collective manner. In addition to electrostatic and van der Waals interactions, those proteins also experience membrane-mediated interactions, which may be necessary for their functionality. The membrane-mediated interactions originate from perturbation of lipid membranes by the presence of protein inclusions, and have been the subject of intensive research in membrane biophysics. Here we review both theoretical and numerical studies of such interactions for membrane proteins and for nanoparticles bound to lipid membranes.
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Affiliation(s)
- Jie Gao
- Kuang Yaming Honors School, Nanjing University, Nanjing, China
| | - Ruihan Hou
- Kuang Yaming Honors School, Nanjing University, Nanjing, China
| | - Long Li
- State Key Laboratory of Nonlinear Mechanics (LNM) and Beijing Key Laboratory of Engineered Construction and Mechanobiology, Institute of Mechanics, Chinese Academy of Sciences, Beijing, China
| | - Jinglei Hu
- Kuang Yaming Honors School, Nanjing University, Nanjing, China
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8
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Li L, Hu J, Shi X, Różycki B, Song F. Interplay between cooperativity of intercellular receptor-ligand binding and coalescence of nanoscale lipid clusters in adhering membranes. SOFT MATTER 2021; 17:1912-1920. [PMID: 33416062 DOI: 10.1039/d0sm01904f] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Adhesion of biological cells is mediated by the specific binding of receptors and ligands which are typically large proteins spanning through the plasma membranes of the contacting cells. The receptors and ligands can exhibit affinity for nanoscale lipid clusters that form within the plasma membrane. A central question is how these nanoscale lipid clusters physically affect and respond to the receptor-ligand binding during cell adhesion. Within the framework of classical statistical mechanics we find that the receptor-ligand binding reduces the threshold energy for lipid clusters to coalesce into mesoscale domains by up to ∼50%, and that the formation of these domains induces significant cooperativity of the receptor-ligand binding. The interplay between the receptor-ligand binding cooperativity and the lipid domain formation manifests acute sensitivity of the membrane system to changes in control parameters. This sensitivity can be crucial in cell signaling and immune responses.
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Affiliation(s)
- Long Li
- State Key Laboratory of Nonlinear Mechanics and Beijing Key Laboratory of Engineered Construction and Mechanobiology, Institute of Mechanics, Chinese Academy of Sciences, Beijing, China.
| | - Jinglei Hu
- Kuang Yaming Honors School and Institute for Brain Sciences, Nanjing University, Nanjing, China.
| | - Xinghua Shi
- National Center for Nanoscience and Technology of China, Beijing, China
| | - Bartosz Różycki
- Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, Warsaw, Poland.
| | - Fan Song
- State Key Laboratory of Nonlinear Mechanics and Beijing Key Laboratory of Engineered Construction and Mechanobiology, Institute of Mechanics, Chinese Academy of Sciences, Beijing, China. and School of Engineering Science, University of Chinese Academy of Sciences, Beijing, China
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9
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Large-scale simulation of biomembranes incorporating realistic kinetics into coarse-grained models. Nat Commun 2020; 11:2951. [PMID: 32528158 PMCID: PMC7289815 DOI: 10.1038/s41467-020-16424-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Accepted: 04/28/2020] [Indexed: 12/12/2022] Open
Abstract
Biomembranes are two-dimensional assemblies of phospholipids that are only a few nanometres thick, but form micrometre-sized structures vital to cellular function. Explicit molecular modelling of biologically relevant membrane systems is computationally expensive due to the large number of solvent particles and slow membrane kinetics. Coarse-grained solvent-free membrane models offer efficient sampling but sacrifice realistic kinetics, thereby limiting the ability to predict pathways and mechanisms of membrane processes. Here, we present a framework for integrating coarse-grained membrane models with continuum-based hydrodynamics. This framework facilitates efficient simulation of large biomembrane systems with large timesteps, while achieving realistic equilibrium and non-equilibrium kinetics. It helps to bridge between the nanometer/nanosecond spatiotemporal resolutions of coarse-grained models and biologically relevant time- and lengthscales. As a demonstration, we investigate fluctuations of red blood cells, with varying cytoplasmic viscosities, in 150-milliseconds-long trajectories, and compare kinetic properties against single-cell experimental observations.
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10
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MacKay L, Khadra A. The bioenergetics of integrin-based adhesion, from single molecule dynamics to stability of macromolecular complexes. Comput Struct Biotechnol J 2020; 18:393-416. [PMID: 32128069 PMCID: PMC7044673 DOI: 10.1016/j.csbj.2020.02.003] [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: 11/07/2019] [Revised: 02/03/2020] [Accepted: 02/04/2020] [Indexed: 12/22/2022] Open
Abstract
The forces actively generated by motile cells must be transmitted to their environment in a spatiotemporally regulated manner, in order to produce directional cellular motion. This task is accomplished through integrin-based adhesions, large macromolecular complexes that link the actin-cytoskelton inside the cell to its external environment. Despite their relatively large size, adhesions exhibit rapid dynamics, switching between assembly and disassembly in response to chemical and mechanical cues exerted by cytoplasmic biochemical signals, and intracellular/extracellular forces, respectively. While in material science, force typically disrupts adhesive contact, in this biological system, force has a more nuanced effect, capable of causing assembly or disassembly. This initially puzzled experimentalists and theorists alike, but investigation into the mechanisms regulating adhesion dynamics have progressively elucidated the origin of these phenomena. This review provides an overview of recent studies focused on the theoretical understanding of adhesion assembly and disassembly as well as the experimental studies that motivated them. We first concentrate on the kinetics of integrin receptors, which exhibit a complex response to force, and then investigate how this response manifests itself in macromolecular adhesion complexes. We then turn our attention to studies of adhesion plaque dynamics that link integrins to the actin-cytoskeleton, and explain how force can influence the assembly/disassembly of these macromolecular structure. Subsequently, we analyze the effect of force on integrins populations across lengthscales larger than single adhesions. Finally, we cover some theoretical studies that have considered both integrins and the adhesion plaque and discuss some potential future avenues of research.
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Affiliation(s)
- Laurent MacKay
- Department of Physiology, McGill University, 3655 Promenade Sir William Osler, Montreal, Quebec, Canada
| | - Anmar Khadra
- Department of Physiology, McGill University, 3655 Promenade Sir William Osler, Montreal, Quebec, Canada
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11
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Zhai C, Li T, Shi H, Yeo J. Discovery and design of soft polymeric bio-inspired materials with multiscale simulations and artificial intelligence. J Mater Chem B 2020; 8:6562-6587. [DOI: 10.1039/d0tb00896f] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Establishing the “Materials 4.0” paradigm requires intimate knowledge of the virtual space in materials design.
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Affiliation(s)
- Chenxi Zhai
- J2 Lab for Engineering Living Materials
- Sibley School of Mechanical and Aerospace Engineering
- Cornell University
- Ithaca
- USA
| | - Tianjiao Li
- J2 Lab for Engineering Living Materials
- Sibley School of Mechanical and Aerospace Engineering
- Cornell University
- Ithaca
- USA
| | - Haoyuan Shi
- J2 Lab for Engineering Living Materials
- Sibley School of Mechanical and Aerospace Engineering
- Cornell University
- Ithaca
- USA
| | - Jingjie Yeo
- J2 Lab for Engineering Living Materials
- Sibley School of Mechanical and Aerospace Engineering
- Cornell University
- Ithaca
- USA
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12
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Li L, Hu J, Li L, Song F. Binding constant of membrane-anchored receptors and ligands that induce membrane curvatures. SOFT MATTER 2019; 15:3507-3514. [PMID: 30912540 DOI: 10.1039/c8sm02504e] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Cell adhesion is crucial for immune response, tissue formation, and cell locomotion. The adhesion process is mediated by the specific binding of membrane-anchored receptor and ligand proteins. These adhesion proteins are in contact with the membranes and may generate curvature, which has been shown for a number of membrane proteins to play an important role in membrane remodeling. An important question remains of whether the local membrane curvatures induced by the adhesion proteins affect their binding. We've performed Monte Carlo simulations of a mesoscopic model for membrane adhesion via the specific binding of curvature-inducing receptors and ligands. We find that the curvatures induced by the adhesion proteins do affect their binding equilibrium constant. We presented a theory that takes into account the membrane deformations and protein-protein interactions due to the induced curvatures, and agrees quantitatively with our simulation results. Our study suggests that the ability to induce membrane curvatures represents a molecular property of the adhesion proteins and should be carefully considered in experimental characterization of the binding affinity.
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Affiliation(s)
- Long Li
- State Key Laboratory of Nonlinear Mechanics (LNM) and Beijing Key Laboratory of Engineered Construction and Mechanobiology, Institute of Mechanics, Chinese Academy of Sciences, Beijing, 100190, China.
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13
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Li L, Hu J, Xu G, Song F. Binding constant of cell adhesion receptors and substrate-immobilized ligands depends on the distribution of ligands. Phys Rev E 2018; 97:012405. [PMID: 29448355 DOI: 10.1103/physreve.97.012405] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Indexed: 12/16/2022]
Abstract
Cell-cell adhesion and the adhesion of cells to tissues and extracellular matrix, which are pivotal for immune response, tissue development, and cell locomotion, depend sensitively on the binding constant of receptor and ligand molecules anchored on the apposing surfaces. An important question remains of whether the immobilization of ligands affects the affinity of binding with cell adhesion receptors. We have investigated the adhesion of multicomponent membranes to a flat substrate coated with immobile ligands using Monte Carlo simulations of a statistical mesoscopic model with biologically relevant parameters. We find that the binding of the adhesion receptors to ligands immobilized on the substrate is strongly affected by the ligand distribution. In the case of ligand clusters, the receptor-ligand binding constant can be significantly enhanced due to the less translational entropy loss of lipid-raft domains in the model cell membranes upon the formation of additional complexes. For ligands randomly or uniformly immobilized on the substrate, the binding constant is rather decreased since the receptors localized in lipid-raft domains have to pay an energetic penalty in order to bind ligands. Our findings help to understand why cell-substrate adhesion experiments for measuring the impact of lipid rafts on the receptor-ligand interactions led to contradictory results.
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Affiliation(s)
- Long Li
- State Key Laboratory of Nonlinear Mechanics (LNM) and Beijing Key Laboratory of Engineered Construction and Mechanobiology, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, China
| | - Jinglei Hu
- Kuang Yaming Honors School, Nanjing University, Nanjing 210023, China.,Shenzhen Institute of Research, Nanjing University, Shenzhen 518057, China
| | - Guangkui Xu
- School of Aerospace, Xi'an Jiaotong University, Xi'an 710049, China
| | - Fan Song
- State Key Laboratory of Nonlinear Mechanics (LNM) and Beijing Key Laboratory of Engineered Construction and Mechanobiology, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, China.,School of Engineering Science, University of Chinese Academy of Sciences, Beijing 100049, China
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14
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Water permeation in polymeric membranes: Mechanism and synthetic strategy for water-inhibiting functional polymers. J Memb Sci 2018. [DOI: 10.1016/j.memsci.2018.07.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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15
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Abstract
Besides direct protein-protein interactions, indirect interactions mediated by membranes play an important role for the assembly and cooperative function of proteins in membrane shaping and adhesion. The intricate shapes of biological membranes are generated by proteins that locally induce membrane curvature. Indirect curvature-mediated interactions between these proteins arise because the proteins jointly affect the bending energy of the membranes. These curvature-mediated interactions are attractive for crescent-shaped proteins and are a driving force in the assembly of the proteins during membrane tubulation. Membrane adhesion results from the binding of receptor and ligand proteins that are anchored in the apposing membranes. The binding of these proteins strongly depends on nanoscale shape fluctuations of the membranes, leading to a fluctuation-mediated binding cooperativity. A length mismatch between receptor-ligand complexes in membrane adhesion zones causes repulsive curvature-mediated interactions that are a driving force for the length-based segregation of proteins during membrane adhesion.
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Affiliation(s)
- Thomas R Weikl
- Department of Theory and Bio-Systems, Max Planck Institute of Colloids and Interfaces, 14424 Potsdam, Germany;
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16
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Li L, Hu J, Shi X, Shao Y, Song F. Lipid rafts enhance the binding constant of membrane-anchored receptors and ligands. SOFT MATTER 2017; 13:4294-4304. [PMID: 28573272 DOI: 10.1039/c7sm00572e] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Gaining insights into the binding of membrane-anchored receptors and ligands that mediate cell adhesion and signal transduction is of great significance for understanding numerous physiological processes driven by intercellular communication. Lipid rafts, microdomains in cell membranes enriched in cholesterol and saturated lipids such as sphingomyelin, are believed to serve as the essential platforms to recruit protein molecules for biological functions. An important question remains how the lipid rafts affect the binding constant of membrane-anchored receptors and ligands. We have investigated the adhesion of multicomponent membranes by using Monte Carlo simulations of a mesoscopic model with biologically relevant parameters. We find that the preferential partitioning of membrane-anchored receptor and ligand proteins in the lipid rafts significantly increases the binding constant of those proteins, in cooperation with the shape fluctuations of the membranes caused by thermal excitations. The binding constant can even be greater than that of the same receptors and ligands anchored to two apposing supported, planar membranes without shape fluctuations. The membrane shape fluctuations facilitate the binding of the anchored receptors and ligands, in contrast to the case of homogeneous membranes. Our results suggest that cells might regulate the binding of membrane-anchored receptor and ligand proteins by modulating the properties of lipid rafts such as area fraction, size and the affinity of rafts to the proteins.
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Affiliation(s)
- Long Li
- State Key Laboratory of Nonlinear Mechanics (LNM) and Beijing Key Laboratory of Engineered Construction and Mechanobiology, Institute of Mechanics, Chinese Academy of Sciences, Beijing, 100190, China.
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17
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Liu YT, Li YR, Wang X. Spontaneous onion shape vesicle formation and fusion of comb-like block copolymers studied by dissipative particle dynamics. RSC Adv 2017. [DOI: 10.1039/c6ra26127b] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The formation of an onion shape vesicle.
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Affiliation(s)
- Ying-Tao Liu
- School of Chemistry and Chemical Engineering
- Ningxia University
- Yinchuan
- China
| | - Yan-Rong Li
- School of Chemistry and Chemical Engineering
- Ningxia University
- Yinchuan
- China
| | - Xin Wang
- School of Chemistry and Chemical Engineering
- Ningxia University
- Yinchuan
- China
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18
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A Rough Energy Landscape to Describe Surface-Linked Antibody and Antigen Bond Formation. Sci Rep 2016; 6:35193. [PMID: 27731375 PMCID: PMC5059681 DOI: 10.1038/srep35193] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Accepted: 09/27/2016] [Indexed: 11/08/2022] Open
Abstract
Antibodies and B cell receptors often bind their antigen at cell-cell interface while both molecular species are surface-bound, which impacts bond kinetics and function. Despite the description of complex energy landscapes for dissociation kinetics which may also result in significantly different association kinetics, surface-bound molecule (2D) association kinetics usually remain described by an on-rate due to crossing of a single free energy barrier, and few experimental works have measured association kinetics under conditions implying force and two-dimensional relative ligand-receptor motion. We use a new laminar flow chamber to measure 2D bond formation with systematic variation of the distribution of encounter durations between antigen and antibody, in a range from 0.1 to 10 ms. Under physiologically relevant forces, 2D association is 100-fold slower than 3D association as studied by surface plasmon resonance assays. Supported by brownian dynamics simulations, our results show that a minimal encounter duration is required for 2D association; an energy landscape featuring a rough initial part might be a reasonable way of accounting for this. By systematically varying the temperature of our experiments, we evaluate roughness at 2kBT, in the range of previously proposed rough parts of landscapes models during dissociation.
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Xu GK, Hu J, Lipowsky R, Weikl TR. Binding constants of membrane-anchored receptors and ligands: A general theory corroborated by Monte Carlo simulations. J Chem Phys 2016; 143:243136. [PMID: 26723621 DOI: 10.1063/1.4936134] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Adhesion processes of biological membranes that enclose cells and cellular organelles are essential for immune responses, tissue formation, and signaling. These processes depend sensitively on the binding constant K2D of the membrane-anchored receptor and ligand proteins that mediate adhesion, which is difficult to measure in the "two-dimensional" (2D) membrane environment of the proteins. An important problem therefore is to relate K2D to the binding constant K3D of soluble variants of the receptors and ligands that lack the membrane anchors and are free to diffuse in three dimensions (3D). In this article, we present a general theory for the binding constants K2D and K3D of rather stiff proteins whose main degrees of freedom are translation and rotation, along membranes and around anchor points "in 2D," or unconstrained "in 3D." The theory generalizes previous results by describing how K2D depends both on the average separation and thermal nanoscale roughness of the apposing membranes, and on the length and anchoring flexibility of the receptors and ligands. Our theoretical results for the ratio K2D/K3D of the binding constants agree with detailed results from Monte Carlo simulations without any data fitting, which indicates that the theory captures the essential features of the "dimensionality reduction" due to membrane anchoring. In our Monte Carlo simulations, we consider a novel coarse-grained model of biomembrane adhesion in which the membranes are represented as discretized elastic surfaces, and the receptors and ligands as anchored molecules that diffuse continuously along the membranes and rotate at their anchor points.
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Affiliation(s)
- Guang-Kui Xu
- Department of Theory and Bio-Systems, Max Planck Institute of Colloids and Interfaces, 14424 Potsdam, Germany
| | - Jinglei Hu
- Department of Theory and Bio-Systems, Max Planck Institute of Colloids and Interfaces, 14424 Potsdam, Germany
| | - Reinhard Lipowsky
- Department of Theory and Bio-Systems, Max Planck Institute of Colloids and Interfaces, 14424 Potsdam, Germany
| | - Thomas R Weikl
- Department of Theory and Bio-Systems, Max Planck Institute of Colloids and Interfaces, 14424 Potsdam, Germany
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Weikl TR, Hu J, Xu GK, Lipowsky R. Binding equilibrium and kinetics of membrane-anchored receptors and ligands in cell adhesion: Insights from computational model systems and theory. Cell Adh Migr 2016; 10:576-589. [PMID: 27294442 PMCID: PMC5079412 DOI: 10.1080/19336918.2016.1180487] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Accepted: 04/13/2016] [Indexed: 10/21/2022] Open
Abstract
The adhesion of cell membranes is mediated by the binding of membrane-anchored receptor and ligand proteins. In this article, we review recent results from simulations and theory that lead to novel insights on how the binding equilibrium and kinetics of these proteins is affected by the membranes and by the membrane anchoring and molecular properties of the proteins. Simulations and theory both indicate that the binding equilibrium constant [Formula: see text] and the on- and off-rate constants of anchored receptors and ligands in their 2-dimensional (2D) membrane environment strongly depend on the membrane roughness from thermally excited shape fluctuations on nanoscales. Recent theory corroborated by simulations provides a general relation between [Formula: see text] and the binding constant [Formula: see text] of soluble variants of the receptors and ligands that lack the membrane anchors and are free to diffuse in 3 dimensions (3D).
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Affiliation(s)
- Thomas R. Weikl
- Max Planck Institute of Colloids and Interfaces, Department of Theory and Bio-Systems, Potsdam, Germany
| | - Jinglei Hu
- Max Planck Institute of Colloids and Interfaces, Department of Theory and Bio-Systems, Potsdam, Germany
- Kuang Yaming Honors School, Nanjing University, Nanjing, China
| | - Guang-Kui Xu
- Max Planck Institute of Colloids and Interfaces, Department of Theory and Bio-Systems, Potsdam, Germany
- International Center for Applied Mechanics, State Key Laboratory for Strength and Vibration of Mechanical Structures, Xi'an Jiaotong University, Xi'an, China
| | - Reinhard Lipowsky
- Max Planck Institute of Colloids and Interfaces, Department of Theory and Bio-Systems, Potsdam, Germany
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Xu GK, Qian J, Hu J. The glycocalyx promotes cooperative binding and clustering of adhesion receptors. SOFT MATTER 2016; 12:4572-4583. [PMID: 27102288 DOI: 10.1039/c5sm03139g] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Cell adhesion plays a pivotal role in various biological processes, e.g., immune responses, cancer metastasis, and stem cell differentiation. The adhesion behaviors depend subtly on the binding kinetics of receptors and ligands restricted at the cell-substrate interfaces. Although much effort has been directed toward investigating the kinetics of adhesion molecules, the role of the glycocalyx, anchored on cell surfaces as an exterior layer, is still unclear. In this paper, we propose a theoretical approach to study the collective binding kinetics of a few and a large number of binders in the presence of the glycocalyx, representing the cases of initial and mature adhesions of cells, respectively. The analytical results are validated by finding good agreement with our Monte Carlo simulations. In the force loading case, the on-rate and affinity increase as more bonds form, whereas this cooperative effect is not observed in the displacement loading case. The increased thickness and stiffness of the glycocalyx tend to decrease the affinity for a few bonds, while they have less influence on the affinity for a large number of bonds. Moreover, for a flexible membrane with thermally-excited shape fluctuations, the glycocalyx is exhibited to promote the formation of bond clusters, mainly due to the cooperative binding of binders. This study helps to understand the cooperative kinetics of adhesion receptors under physiologically relevant loading conditions and sheds light on the novel role of the glycocalyx in cell adhesion.
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Affiliation(s)
- Guang-Kui Xu
- International Center for Applied Mechanics, State Key Laboratory for Strength and Vibration of Mechanical Structures, School of Aerospace, Xi'an Jiaotong University, Xi'an 710049, China.
| | - Jin Qian
- Department of Engineering Mechanics, Soft Matter Research Center, Zhejiang University, Hangzhou 310027, China
| | - Jinglei Hu
- Kuang Yaming Honors School, Nanjing University, Nanjing 210023, China
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