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Zhu M, Xu H, Jin Y, Kong X, Xu B, Liu Y, Yu H. Synaptotagmin-1 undergoes phase separation to regulate its calcium-sensitive oligomerization. J Cell Biol 2024; 223:e202311191. [PMID: 38980206 PMCID: PMC11232894 DOI: 10.1083/jcb.202311191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2023] [Revised: 04/17/2024] [Accepted: 06/11/2024] [Indexed: 07/10/2024] Open
Abstract
Synaptotagmin-1 (Syt1) is a calcium sensor that regulates synaptic vesicle fusion in synchronous neurotransmitter release. Syt1 interacts with negatively charged lipids and the SNARE complex to control the fusion event. However, it remains incompletely understood how Syt1 mediates Ca2+-trigged synaptic vesicle fusion. Here, we discovered that Syt1 undergoes liquid-liquid phase separation (LLPS) to form condensates both in vitro and in living cells. Syt1 condensates play a role in vesicle attachment to the PM and efficiently recruit SNAREs and complexin, which may facilitate the downstream synaptic vesicle fusion. We observed that Syt1 condensates undergo a liquid-to-gel-like phase transition, reflecting the formation of Syt1 oligomers. The phase transition can be blocked or reversed by Ca2+, confirming the essential role of Ca2+ in Syt1 oligomer disassembly. Finally, we showed that the Syt1 mutations causing Syt1-associated neurodevelopmental disorder impair the Ca2+-driven phase transition. These findings reveal that Syt1 undergoes LLPS and a Ca2+-sensitive phase transition, providing new insights into Syt1-mediated vesicle fusion.
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Affiliation(s)
- Min Zhu
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Han Xu
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Yulei Jin
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Xiaoxu Kong
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Bingkuan Xu
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Yinghui Liu
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Haijia Yu
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, China
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2
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Aguilar-Pineda J, González-Melchor M. Influence of the Water Model on the Structure and Interactions of the GPR40 Protein with the Lipid Membrane and the Solvent: Rigid versus Flexible Water Models. J Chem Theory Comput 2024; 20:6369-6387. [PMID: 38991114 PMCID: PMC11270832 DOI: 10.1021/acs.jctc.4c00571] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2024] [Revised: 06/07/2024] [Accepted: 06/21/2024] [Indexed: 07/13/2024]
Abstract
G protein-coupled receptors (GPCR) are responsible for modulating various physiological functions and are thus related to the pathophysiology of different diseases. Being potential therapeutic targets, multiple computational methodologies have been developed to analyze their behavior and interactions with other species. The solvent, on the other hand, has received much less attention. In this work, we analyzed the effect of four explicit water models on the structure and interactions of the GPR40 receptor in its apo form. We employed the rigid SPC/E and TIP4P models, and their flexible versions, the FBA/ϵ and TIP4P/ϵflex. We explored the structural changes and their correlation with some bulk dynamic properties of water. Our results showed an adverse effect on the conservation of the secondary structure of the receptor with all the models due to the breaking of the intramolecular hydrogen bond network, being more evident for the TIP4P models. Notably, all four models brought the receptor to states similar to the active one, modifying the intracellular part of the TM5 and TM6 domains in a "hinge" type movement, allowing the opening of the structure. Regarding the dynamic properties, the rigid models showed results comparable to those obtained in other studies on membrane systems. However, flexible models exhibit disparities in the molecular representation of systems. Surprisingly, the FBA/ϵ model improves the molecular picture of several properties, even though their agreement with bulk diffusion is poorer. These findings reinforce our idea that exploring other water models or improving the current ones, to better represent the membrane interface, can lead to a positive impact on the description of the signal transduction mechanisms and the search of new drugs by targeting these receptors.
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Affiliation(s)
- Jorge
Alberto Aguilar-Pineda
- Instituto de Física
“Luis Rivera Terrazas”, Benemérita Universidad
Autónoma de Puebla, Av San Claudio, Cd Universitaria, Apdo. Postal
J-48, Puebla 72570, México
| | - Minerva González-Melchor
- Instituto de Física
“Luis Rivera Terrazas”, Benemérita Universidad
Autónoma de Puebla, Av San Claudio, Cd Universitaria, Apdo. Postal
J-48, Puebla 72570, México
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3
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Karyu H, Niki T, Sorimachi Y, Hata S, Shimabukuro-Demoto S, Hirabayashi T, Mukai K, Kasahara K, Takubo K, Goda N, Honke K, Taguchi T, Sorimachi H, Toyama-Sorimachi N. Collaboration between a cis-interacting natural killer cell receptor and membrane sphingolipid is critical for the phagocyte function. Front Immunol 2024; 15:1401294. [PMID: 38720899 PMCID: PMC11076679 DOI: 10.3389/fimmu.2024.1401294] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2024] [Accepted: 04/12/2024] [Indexed: 05/12/2024] Open
Abstract
Inhibitory natural killer (NK) cell receptors recognize MHC class I (MHC-I) in trans on target cells and suppress cytotoxicity. Some NK cell receptors recognize MHC-I in cis, but the role of this interaction is uncertain. Ly49Q, an atypical Ly49 receptor expressed in non-NK cells, binds MHC-I in cis and mediates chemotaxis of neutrophils and type I interferon production by plasmacytoid dendritic cells. We identified a lipid-binding motif in the juxtamembrane region of Ly49Q and found that Ly49Q organized functional membrane domains comprising sphingolipids via sulfatide binding. Ly49Q recruited actin-remodeling molecules to an immunoreceptor tyrosine-based inhibitory motif, which enabled the sphingolipid-enriched membrane domain to mediate complicated actin remodeling at the lamellipodia and phagosome membranes during phagocytosis. Thus, Ly49Q facilitates integrative regulation of proteins and lipid species to construct a cell type-specific membrane platform. Other Ly49 members possess lipid binding motifs; therefore, membrane platform organization may be a primary role of some NK cell receptors.
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Affiliation(s)
- Hitomi Karyu
- Division of Human Immunology, International Vaccine Design Center, The Institute of Medical Science, The University of Tokyo (IMSUT), Tokyo, Japan
| | - Takahiro Niki
- Laboratory for Neural Cell Dynamics, RIKEN Center for Brain Science, Saitama, Japan
| | - Yuriko Sorimachi
- Department of Life Science and Medical Bioscience, School of Advanced Science and Engineering, Waseda University, Tokyo, Japan
- Department of Stem Cell Biology, Research Institute, National Center for Global Health and Medicine, Shinjuku, Tokyo, Japan
| | - Shoji Hata
- Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan
| | - Shiho Shimabukuro-Demoto
- Division of Human Immunology, International Vaccine Design Center, The Institute of Medical Science, The University of Tokyo (IMSUT), Tokyo, Japan
| | - Tetsuya Hirabayashi
- Laboratory of Biomembrane, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan
| | - Kojiro Mukai
- Department of Integrative Life Sciences, Graduate School of Life Sciences, Tohoku University, Sendai, Japan
| | - Kohji Kasahara
- Laboratory of Biomembrane, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan
| | - Keiyo Takubo
- Department of Stem Cell Biology, Research Institute, National Center for Global Health and Medicine, Shinjuku, Tokyo, Japan
| | - Nobuhito Goda
- Department of Life Science and Medical Bioscience, School of Advanced Science and Engineering, Waseda University, Tokyo, Japan
| | - Koichi Honke
- Department of Biochemistry and Kochi System Glycobiology Center, Kochi University Medical School, Kochi, Japan
| | - Tomohiko Taguchi
- Department of Integrative Life Sciences, Graduate School of Life Sciences, Tohoku University, Sendai, Japan
| | - Hiroyuki Sorimachi
- Department of Life Science and Medical Bioscience, School of Advanced Science and Engineering, Waseda University, Tokyo, Japan
| | - Noriko Toyama-Sorimachi
- Division of Human Immunology, International Vaccine Design Center, The Institute of Medical Science, The University of Tokyo (IMSUT), Tokyo, Japan
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4
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Kang C, Fujioka K, Sun R. Atomistic Insight into the Lipid Nanodomains of Synaptic Vesicles. J Phys Chem B 2024; 128:2707-2716. [PMID: 38325816 DOI: 10.1021/acs.jpcb.3c07982] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2024]
Abstract
Membrane curvature, once regarded as a passive consequence of membrane composition and cellular architecture, has been shown to actively modulate various properties of the cellular membrane. These changes could also lead to segregation of the constituents of the membrane, generating nanodomains with precise biological properties. Proteins often linked with neurodegeneration (e.g., tau, alpha-synuclein) exhibit an unintuitive affinity for synaptic vesicles in neurons, which are reported to lack distinct, ordered nanodomains based on their composition. In this study, all-atom molecular dynamics simulations are used to study a full-scale synaptic vesicle of realistic Gaussian curvature and its effect on the membrane dynamics and lipid nanodomain organization. Compelling indicators of nanodomain formation, from the perspective of composition, surface areas per lipid, order parameter, and domain lifetime, are identified in the vesicle membrane, which are absent in a flat bilayer of the same lipid composition. Therefore, our study supports the idea that curvature may induce phase separation in an otherwise fluid, disordered membrane.
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Affiliation(s)
- Christopher Kang
- Department of Chemistry, The University of Hawai'i, Ma̅noa, 2545 McCarthy Mall, Honolulu, Hawaii 96822, United States
| | - Kazuumi Fujioka
- Department of Chemistry, The University of Hawai'i, Ma̅noa, 2545 McCarthy Mall, Honolulu, Hawaii 96822, United States
| | - Rui Sun
- Department of Chemistry, The University of Hawai'i, Ma̅noa, 2545 McCarthy Mall, Honolulu, Hawaii 96822, United States
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5
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Balakrishnan M, Kenworthy AK. Lipid Peroxidation Drives Liquid-Liquid Phase Separation and Disrupts Raft Protein Partitioning in Biological Membranes. J Am Chem Soc 2024; 146:1374-1387. [PMID: 38171000 PMCID: PMC10797634 DOI: 10.1021/jacs.3c10132] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Revised: 12/06/2023] [Accepted: 12/07/2023] [Indexed: 01/05/2024]
Abstract
The peroxidation of membrane lipids by free radicals contributes to aging, numerous diseases, and ferroptosis, an iron-dependent form of cell death. Peroxidation changes the structure and physicochemical properties of lipids, leading to bilayer thinning, altered fluidity, and increased permeability of membranes in model systems. Whether and how lipid peroxidation impacts the lateral organization of proteins and lipids in biological membranes, however, remains poorly understood. Here, we employ cell-derived giant plasma membrane vesicles (GPMVs) as a model to investigate the impact of lipid peroxidation on ordered membrane domains, often termed membrane rafts. We show that lipid peroxidation induced by the Fenton reaction dramatically enhances the phase separation propensity of GPMVs into coexisting liquid-ordered (Lo) and liquid-disordered (Ld) domains and increases the relative abundance of the disordered phase. Peroxidation also leads to preferential accumulation of peroxidized lipids and 4-hydroxynonenal (4-HNE) adducts in the disordered phase, decreased lipid packing in both Lo and Ld domains, and translocation of multiple classes of raft proteins out of ordered domains. These findings indicate that the peroxidation of plasma membrane lipids disturbs many aspects of membrane rafts, including their stability, abundance, packing, and protein and lipid composition. We propose that these disruptions contribute to the pathological consequences of lipid peroxidation during aging and disease and thus serve as potential targets for therapeutic intervention.
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Affiliation(s)
- Muthuraj Balakrishnan
- Center
for Membrane and Cell Physiology, University
of Virginia, Charlottesville, Virginia 22903, United States
- Department
of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, Virginia 22903, United States
| | - Anne K. Kenworthy
- Center
for Membrane and Cell Physiology, University
of Virginia, Charlottesville, Virginia 22903, United States
- Department
of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, Virginia 22903, United States
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6
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Breton V, Nazac P, Boulet D, Danglot L. Molecular mapping of neuronal architecture using STORM microscopy and new fluorescent probes for SMLM imaging. NEUROPHOTONICS 2024; 11:014414. [PMID: 38464866 PMCID: PMC10923464 DOI: 10.1117/1.nph.11.1.014414] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/26/2023] [Revised: 01/27/2024] [Accepted: 01/31/2024] [Indexed: 03/12/2024]
Abstract
Imaging neuronal architecture has been a recurrent challenge over the years, and the localization of synaptic proteins is a frequent challenge in neuroscience. To quantitatively detect and analyze the structure of synapses, we recently developed free SODA software to detect the association of pre and postsynaptic proteins. To fully take advantage of spatial distribution analysis in complex cells, such as neurons, we also selected some new dyes for plasma membrane labeling. Using Icy SODA plugin, we could detect and analyze synaptic association in both conventional and single molecule localization microscopy, giving access to a molecular map at the nanoscale level. To replace those molecular distributions within the neuronal three-dimensional (3D) shape, we used MemBright probes and 3D STORM analysis to decipher the entire 3D shape of various dendritic spine types at the single-molecule resolution level. We report here the example of synaptic proteins within neuronal mask, but these tools have a broader spectrum of interest since they can be used whatever the proteins or the cellular type. Altogether with SODA plugin, MemBright probes thus provide the perfect toolkit to decipher a nanometric molecular map of proteins within a 3D cellular context.
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Affiliation(s)
- Victor Breton
- Université Paris Cité, Institute of Psychiatry and Neuroscience of Paris, INSERM U1266, Membrane Traffic in Healthy and Diseased Brain, Paris, France
| | - Paul Nazac
- Université Paris Cité, Institute of Psychiatry and Neuroscience of Paris, INSERM U1266, Membrane Traffic in Healthy and Diseased Brain, Paris, France
| | - David Boulet
- Université Paris Cité, Institute of Psychiatry and Neuroscience of Paris, INSERM U1266, Membrane Traffic in Healthy and Diseased Brain, Paris, France
- Université Paris Cité, Institute of Psychiatry and Neuroscience of Paris, INSERM U1266, NeurImag Core Facility, Paris, France
| | - Lydia Danglot
- Université Paris Cité, Institute of Psychiatry and Neuroscience of Paris, INSERM U1266, Membrane Traffic in Healthy and Diseased Brain, Paris, France
- Université Paris Cité, Institute of Psychiatry and Neuroscience of Paris, INSERM U1266, NeurImag Core Facility, Paris, France
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7
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Socrier L, Steinem C. Photo-Lipids: Light-Sensitive Nano-Switches to Control Membrane Properties. Chempluschem 2023; 88:e202300203. [PMID: 37395458 DOI: 10.1002/cplu.202300203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Revised: 06/30/2023] [Accepted: 07/03/2023] [Indexed: 07/04/2023]
Abstract
Biological membranes are described as a complex mixture of lipids and proteins organized according to thermodynamic principles. This chemical and spatial complexity can lead to specialized functional membrane domains enriched with specific lipids and proteins. The interaction between lipids and proteins restricts their lateral diffusion and range of motion, thus altering their function. One approach to investigating these membrane properties is to use chemically accessible probes. In particular, photo-lipids, which contain a light-sensitive azobenzene moiety that changes its configuration from trans- to cis- upon light irradiation, have recently gained popularity for modifying membrane properties. These azobenzene-derived lipids serve as nanotools for manipulating lipid membranes in vitro and in vivo. Here, we will discuss the use of these compounds in artificial and biological membranes as well as their application in drug delivery. We will focus mainly on changes in the membrane's physical properties as well as lipid membrane domains in phase-separated liquid-ordered/liquid-disordered bilayers driven by light, and how these changes in membrane physical properties alter transmembrane protein function.
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Affiliation(s)
- Larissa Socrier
- Max Planck Institute for Dynamics and Self-Organization, Am Faßberg 17, 37077, Göttingen, Germany
| | - Claudia Steinem
- Institute of Organic and Biomolecular Chemistry, Georg-August-Universität, Tammannstraße 2, 37077, Göttingen, Germany
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8
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Trybus M, Hryniewicz-Jankowska A, Wójtowicz K, Trombik T, Czogalla A, Sikorski AF. EFR3A: a new raft domain organizing protein? Cell Mol Biol Lett 2023; 28:86. [PMID: 37880612 PMCID: PMC10601247 DOI: 10.1186/s11658-023-00497-y] [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: 03/12/2023] [Accepted: 10/04/2023] [Indexed: 10/27/2023] Open
Abstract
BACKGROUND Membrane rafts play a crucial role in the regulation of many important biological processes. Our previous data suggest that specific interactions of flotillins with MPP1 are responsible for membrane raft domain organization and regulation in erythroid cells. Interaction of the flotillin-based protein network with specific membrane components underlies the mechanism of raft domain formation and regulation, including in cells with low expression of MPP1. METHODS We sought to identify other flotillin partners via the immobilized recombinant flotillin-2-based affinity approach and mass spectrometry technique. The results were further confirmed via immunoblotting and via co-immunoprecipitation. In order to study the effect of the candidate protein on the physicochemical properties of the plasma membrane, the gene was knocked down via siRNA, and fluorescence lifetime imaging microscopy and spot-variation fluorescence correlation spectroscopy was employed. RESULTS EFR3A was identified as a candidate protein that interacts with flotillin-2. Moreover, this newly discovered interaction was demonstrated via overlay assay using recombinant EFR3A and flotillin-2. EFR3A is a stable component of the detergent-resistant membrane fraction of HeLa cells, and its presence was sensitive to the removal of cholesterol. While silencing the EFR3A gene, we observed decreased order of the plasma membrane of living cells or giant plasma membrane vesicles derived from knocked down cells and altered mobility of the raft probe, as indicated via fluorescence lifetime imaging microscopy and spot-variation fluorescence correlation spectroscopy. Moreover, silencing of EFR3A expression was found to disturb epidermal growth factor receptor and phospholipase C gamma phosphorylation and affect epidermal growth factor-dependent cytosolic Ca2+ concentration. CONCLUSIONS Altogether, our results suggest hitherto unreported flotillin-2-EFR3A interaction, which might be responsible for membrane raft organization and regulation. This implies participation of this interaction in the regulation of multiple cellular processes, including those connected with cell signaling which points to the possible role in human health, in particular human cancer biology.
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Affiliation(s)
- Magdalena Trybus
- Department of Cytobiochemistry, Faculty of Biotechnology, University of Wroclaw, F. Joliot-Curie 14a, 50-383, Wroclaw, Poland
| | - Anita Hryniewicz-Jankowska
- Department of Cytobiochemistry, Faculty of Biotechnology, University of Wroclaw, F. Joliot-Curie 14a, 50-383, Wroclaw, Poland
| | - Karolina Wójtowicz
- Department of Biotransformation, Faculty of Biotechnology, University of Wroclaw, F. Joliot-Curie 14a, 50-383, Wroclaw, Poland
| | - Tomasz Trombik
- Chair and Department of Biochemistry and Molecular Biology, Medical University of Lublin, Chodzki 1, 20-093, Lublin, Poland
| | - Aleksander Czogalla
- Department of Cytobiochemistry, Faculty of Biotechnology, University of Wroclaw, F. Joliot-Curie 14a, 50-383, Wroclaw, Poland.
| | - Aleksander F Sikorski
- Research and Development Center, Regional Specialist Hospital, Kamienskiego73a, 51-154, Wroclaw, Poland.
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9
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Balakrishnan M, Kenworthy AK. Lipid peroxidation drives liquid-liquid phase separation and disrupts raft protein partitioning in biological membranes. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.12.557355. [PMID: 37745342 PMCID: PMC10515805 DOI: 10.1101/2023.09.12.557355] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/26/2023]
Abstract
The peroxidation of membrane lipids by free radicals contributes to aging, numerous diseases, and ferroptosis, an iron-dependent form of cell death. Peroxidation changes the structure, conformation and physicochemical properties of lipids, leading to major membrane alterations including bilayer thinning, altered fluidity, and increased permeability. Whether and how lipid peroxidation impacts the lateral organization of proteins and lipids in biological membranes, however, remains poorly understood. Here, we employ cell-derived giant plasma membrane vesicles (GPMVs) as a model to investigate the impact of lipid peroxidation on ordered membrane domains, often termed membrane rafts. We show that lipid peroxidation induced by the Fenton reaction dramatically enhances phase separation propensity of GPMVs into co-existing liquid ordered (raft) and liquid disordered (non-raft) domains and increases the relative abundance of the disordered, non-raft phase. Peroxidation also leads to preferential accumulation of peroxidized lipids and 4-hydroxynonenal (4-HNE) adducts in the disordered phase, decreased lipid packing in both raft and non-raft domains, and translocation of multiple classes of proteins out of rafts. These findings indicate that peroxidation of plasma membrane lipids disturbs many aspects of membrane rafts, including their stability, abundance, packing, and protein and lipid composition. We propose that these disruptions contribute to the pathological consequences of lipid peroxidation during aging and disease, and thus serve as potential targets for therapeutic intervention.
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Affiliation(s)
- Muthuraj Balakrishnan
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA USA
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - Anne K. Kenworthy
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA USA
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA, USA
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10
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Abstract
T cell activation is initiated by the recognition of specific antigenic peptides and subsequently accomplished by complex signaling cascades. These aspects have been extensively studied for decades as pivotal factors in the establishment of adaptive immunity. However, how receptors or signaling molecules are organized in the resting state prior to encountering antigens has received less attention. Recent advancements in super-resolution microscopy techniques have revealed topographically controlled pre-formed organization of key molecules involved in antigen recognition and signal transduction on microvillar projections of T cells before activation and substantial effort has been dedicated to characterizing the topological structure of resting T cells over the past decade. This review will summarize our current understanding of how key surface receptors are pre-organized on the T-cell plasma membrane and discuss the potential role of these receptors, which are preassembled prior to ligand binding in the early activation events of T cells.
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Affiliation(s)
- Yunmin Jung
- Department of Nano-Biomedical Engineering, Advanced Science Institute, Yonsei University, Seoul, Republic of Korea
- Center for Nanomedicine, Institute for Basic Science, Seoul, Republic of Korea
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11
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Wang Y, Majd S. Charged Lipids Modulate the Phase Separation in Multicomponent Membranes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:11371-11378. [PMID: 37485979 DOI: 10.1021/acs.langmuir.3c01199] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/25/2023]
Abstract
Phase separation in lipid membranes controls the organization of membrane components and thus regulates membrane-mediated processes. Membrane phase behavior is influenced by the molecular properties of its components and their relative concentrations. Charged lipid species are among the most essential components of lipid membranes, and their impact on the membrane phase behavior is yet to be fully understood. Aiming to provide insight into this impact, this paper investigates how the presence and amount of anionic and cationic lipids affect the phase behavior of multicomponent membranes. Membranes of ternary composition DOPC:DPPC:Chol with two distinct molar ratios were used to test the hypothesis that inclusion of charged lipids with saturated tails, beyond a certain concentration, would impede phase separation in an otherwise phase-separating membrane. Fluorescence microscopy examination of electroformed giant liposomes revealed that when more than half of DOPC in the examined mixtures was replaced with DOPA or DOTAP, phase separation in liposomes was somewhat suppressed, and this effect increased with increasing charged lipid content. This effect depended on the membrane surface charge density as the half-maximal effect was observed at around 0.0072 C Å-2 in all examined cases. The phase-separation suppressing effect of DOPA was neutralized when oppositely charged lipid DOTAP was included in the mixture. Likewise, presence of divalent cation Ca2+ in the solution neutralized the impact of negatively charged DOPA. These results underline the detrimental influence of surface charge density on membrane phase behavior. More importantly, these findings suggest that the charged lipid content in membranes may be a regulator of their phase behavior and open new opportunities for the design of synthetic lipid membranes.
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Affiliation(s)
- Yifei Wang
- Department of Biomedical Engineering, University of Houston, 3551 Cullen Boulevard, Houston, Texas 77204, United States
| | - Sheereen Majd
- Department of Biomedical Engineering, University of Houston, 3551 Cullen Boulevard, Houston, Texas 77204, United States
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12
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Xie J, Chen L, Wu D, Liu S, Pei S, Tang Q, Wang Y, Ou M, Zhu Z, Ruan S, Wang M, Shi J. Significance of liquid-liquid phase separation (LLPS)-related genes in breast cancer: a multi-omics analysis. Aging (Albany NY) 2023; 15:5592-5610. [PMID: 37338518 PMCID: PMC10333080 DOI: 10.18632/aging.204812] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Accepted: 05/27/2023] [Indexed: 06/21/2023]
Abstract
Currently, the role of liquid-liquid phase separation (LLPS) in cancer has been preliminarily explained. However, the significance of LLPS in breast cancer is unclear. In this study, single cell sequencing datasets GSE188600 and GSE198745 for breast cancer were downloaded from the GEO database. Transcriptome sequencing data for breast cancer were downloaded from UCSC database. We divided breast cancer cells into high-LLPS group and low-LLPS group by down dimension clustering analysis of single-cell sequencing data set, and obtained differentially expressed genes between the two groups. Subsequently, weighted co-expression network analysis (WGCNA) was performed on transcriptome sequencing data, and the module genes most associated with LLPS were obtained. COX regression and Lasso regression were performed and the prognostic model was constructed. Subsequently, survival analysis, principal component analysis, clinical correlation analysis, and nomogram construction were used to evaluate the significance of the prognostic model. Finally, cell experiments were used to verify the function of the model's key gene, PGAM1. We constructed a LLPS-related prognosis model consisting of nine genes: POLR3GL, PLAT, NDRG1, HMGB3, HSPH1, PSMD7, PDCD2, NONO and PGAM1. By calculating LLPS-related risk scores, breast cancer patients could be divided into high-risk and low-risk groups, with the high-risk group having a significantly worse prognosis. Cell experiments showed that the activity, proliferation, invasion and healing ability of breast cancer cell lines were significantly decreased after knockdown of the key gene PGAM1 in the model. Our study provides a new idea for prognostic stratification of breast cancer and provides a novel marker: PGAM1.
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Affiliation(s)
- Jiaheng Xie
- Department of Burn and Plastic Surgery, The First Affiliated Hospital of Nanjing Medical University, Jiangsu Province Hospital, Nanjing 210029, Jiangsu, China
| | - Liang Chen
- Department of Hepatobiliary and Pancreatic Surgery, Conversion Therapy Center for Hepatobiliary and Pancreatic Tumors, First Hospital of Jiaxing, Affiliated Hospital of Jiaxing University, Jiaxing 314001, Zhejiang, P. R. China
| | - Dan Wu
- Department of Rheumatology and Immunology, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Nanjing 210031, Jiangsu, China
| | - Shengxuan Liu
- Department of Pediatrics, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, Hubei Province, China
| | - Shengbin Pei
- Department of Breast Surgery, The First Affiliated Hospital of Nanjing Medical University, Jiangsu Province Hospital, Nanjing 210029, Jiangsu, China
| | - Qikai Tang
- Department of Neurosurgery, The First Affiliated Hospital of Nanjing Medical University, Jiangsu Province Hospital, Nanjing 210029, Jiangsu, China
| | - Yue Wang
- Department of Pathology, Basic Medical School, Anhui Medical University, Hefei 230032, Anhui, China
| | - Mengmeng Ou
- Department of Burn and Plastic Surgery, The First Affiliated Hospital of Nanjing Medical University, Jiangsu Province Hospital, Nanjing 210029, Jiangsu, China
| | - Zhechen Zhu
- Department of Burn and Plastic Surgery, The First Affiliated Hospital of Nanjing Medical University, Jiangsu Province Hospital, Nanjing 210029, Jiangsu, China
| | - Shujie Ruan
- Department of Burn and Plastic Surgery, The First Affiliated Hospital of Nanjing Medical University, Jiangsu Province Hospital, Nanjing 210029, Jiangsu, China
| | - Ming Wang
- Department of Burn and Plastic Surgery, The First Affiliated Hospital of Nanjing Medical University, Jiangsu Province Hospital, Nanjing 210029, Jiangsu, China
| | - Jingping Shi
- Department of Burn and Plastic Surgery, The First Affiliated Hospital of Nanjing Medical University, Jiangsu Province Hospital, Nanjing 210029, Jiangsu, China
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13
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Arribas Perez M, Beales PA. Dynamics of asymmetric membranes and interleaflet coupling as intermediates in membrane fusion. Biophys J 2023; 122:1985-1995. [PMID: 36203354 PMCID: PMC10257014 DOI: 10.1016/j.bpj.2022.10.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Revised: 09/19/2022] [Accepted: 10/04/2022] [Indexed: 11/20/2022] Open
Abstract
Membrane fusion is a tool to increase the complexity of model membrane systems. Here, we use silica nanoparticles to fuse liquid-disordered DOPC giant unilamellar vesicles (GUVs) and liquid-ordered DPPC:cholesterol (7:3) GUVs. After fusion, GUVs display large membrane domains as confirmed by fluorescence confocal microscopy. Laurdan spectral imaging of the membrane phases in the fused GUVs shows differences compared with the initial vesicles indicating some lipid redistribution between phase domains as dictated by the tie lines of the phase diagram. Remarkably, using real-time confocal microscopy we were able to record the dynamics of formation of asymmetric membrane domains in hemifused GUVs and detected interleaflet coupling phenomena by which the DOPC-rich liquid-disordered domains in outer monolayer modulates the phase state of the DPPC:cholesterol inner membrane leaflet which transitions from liquid-ordered to liquid-disordered phase. We find that internal membrane stresses generated by membrane asymmetry enhance the efficiency of full fusion compared with our previous studies on symmetric vesicle fusion. Furthermore, under these conditions, the liquid-disordered monolayer dictates the bilayer phase state of asymmetric membrane domains in >90% of observed cases. By comparison to the findings of previous literature, we suggest that the monolayer phase that dominates the bilayer properties could be a mechanoresponsive signaling mechanism sensitive to the local membrane environment.
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Affiliation(s)
- Marcos Arribas Perez
- Astbury Centre for Structural Molecular Biology and School of Chemistry, University of Leeds, Leeds LS2 9JT, UK
| | - Paul A Beales
- Astbury Centre for Structural Molecular Biology and School of Chemistry, University of Leeds, Leeds LS2 9JT, UK; Bragg Centre for Materials Research, University of Leeds, Leeds LS2 9JT, UK.
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14
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Schlegel J, Porebski B, Andronico L, Hanke L, Edwards S, Brismar H, Murrell B, McInerney GM, Fernandez-Capetillo O, Sezgin E. A Multiparametric and High-Throughput Platform for Host-Virus Binding Screens. NANO LETTERS 2023; 23:3701-3707. [PMID: 36892970 PMCID: PMC10176574 DOI: 10.1021/acs.nanolett.2c04884] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Speed is key during infectious disease outbreaks. It is essential, for example, to identify critical host binding factors to pathogens as fast as possible. The complexity of host plasma membrane is often a limiting factor hindering fast and accurate determination of host binding factors as well as high-throughput screening for neutralizing antimicrobial drug targets. Here, we describe a multiparametric and high-throughput platform tackling this bottleneck and enabling fast screens for host binding factors as well as new antiviral drug targets. The sensitivity and robustness of our platform were validated by blocking SARS-CoV-2 particles with nanobodies and IgGs from human serum samples.
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Affiliation(s)
- Jan Schlegel
- Science for Life Laboratory, Department of Women's and Children's Health, Karolinska Institutet, 17165 Solna, Sweden
| | - Bartlomiej Porebski
- Science for Life Laboratory, Division of Genome Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, 17165 Stockholm, Sweden
| | - Luca Andronico
- Science for Life Laboratory, Department of Women's and Children's Health, Karolinska Institutet, 17165 Solna, Sweden
| | - Leo Hanke
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, 17165 Stockholm, Sweden
| | - Steven Edwards
- Science for Life Laboratory, Department of Applied Physics, Royal Institute of Technology, 17165 Solna, Sweden
| | - Hjalmar Brismar
- Science for Life Laboratory, Department of Women's and Children's Health, Karolinska Institutet, 17165 Solna, Sweden
- Science for Life Laboratory, Department of Applied Physics, Royal Institute of Technology, 17165 Solna, Sweden
| | - Ben Murrell
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, 17165 Stockholm, Sweden
| | - Gerald M McInerney
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, 17165 Stockholm, Sweden
| | - Oscar Fernandez-Capetillo
- Science for Life Laboratory, Division of Genome Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, 17165 Stockholm, Sweden
- Genomic Instability Group, Spanish National Cancer Research Centre (CNIO), Madrid 28029, Spain
| | - Erdinc Sezgin
- Science for Life Laboratory, Department of Women's and Children's Health, Karolinska Institutet, 17165 Solna, Sweden
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15
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Nicolson GL, Ferreira de Mattos G. The Fluid-Mosaic model of cell membranes: A brief introduction, historical features, some general principles, and its adaptation to current information. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2023; 1865:184135. [PMID: 36746313 DOI: 10.1016/j.bbamem.2023.184135] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Revised: 01/27/2023] [Accepted: 01/30/2023] [Indexed: 02/07/2023]
Abstract
The Fluid-Mosaic Membrane (FMM) model was originally proposed as a general, nanometer-scale representation of cell membranes (Singer and Nicolson, 1972). The FMM model was based on some general principles, such as thermodynamic considerations, intercalation of globular proteins into a lipid bilayer, independent protein and lipid dynamics, cooperativity and other characteristics. Other models had trimolecular structures or membrane globular lipoprotein units. These latter models were flawed, because they did not allow autonomous lipids, membrane domains or discrete lateral dynamics. The FMM model was also consistent with membrane asymmetry, cis- and trans-membrane linkages and associations of membrane components into multi-molecular complexes and domains. It has remained useful for explaining the basic organizational principles and properties of various biological membranes. New information has been added, such as membrane-associated cytoskeletal assemblies, extracellular matrix interactions, transmembrane controls, specialized lipid-protein domains that differ in compositions, rotational and lateral mobilities, lifetimes, functions, and other characteristics. The presence of dense, structured membrane domains has reduced significantly the extent of fluid-lipid membrane areas, and the FMM model is now considered to be more mosaic and dense than the original proposal.
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Affiliation(s)
- Garth L Nicolson
- Department of Molecular Pathology, The Institute for Molecular Medicine, Huntington Beach, CA 92647, USA.
| | - Gonzalo Ferreira de Mattos
- Laboratory of Ion Channels, Biological Membranes and Cell Signaling, Department of Biophysics, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay
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16
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Li B, Chen X, Zhou Y, Zhao Y, Song T, Wu X, Shi W. Liquid-liquid phase separation of immiscible polymers at double emulsion interfaces for configurable microcapsules. J Colloid Interface Sci 2023; 641:299-308. [PMID: 36934577 DOI: 10.1016/j.jcis.2023.03.072] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Revised: 03/05/2023] [Accepted: 03/10/2023] [Indexed: 03/15/2023]
Abstract
Liquid-liquid phase separation at complex interfaces is a common phenomenon in biological systems and is also a fundamental basis to create synthetic materials in multicomponent mixtures. Understanding the liquid-liquid phase separation in well-defined macromolecular systems is anticipated to shed light on similar behaviors in cross-disciplinary areas. Here we study a series of immiscible polymers and reveal a generic phase diagram of liquid-liquid phase separation at double emulsion interfaces, which depicts the equilibrium structures by interfacial tension and polymer fraction. We further reveal that the interfacial tensions in various systems fall on a linear relationship with spreading coefficients. Based on this theoretical guideline, the liquid-liquid phase separation can be modulated by a low fraction of amphiphilic block copolymers, leading the double emulsion droplets configurable between compartments and anisotropic shapes. The solidified anisotropic microcapsules could provide unique orientation-sensitive optical properties and thermomechanical responses. The theoretical analysis and experimental protocol in this study yield a generalizable strategy to prepare multiphase double emulsions with controlled structures and desired properties.
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Affiliation(s)
- Baihui Li
- Key Laboratory of Functional Polymer Materials of Ministry of Education, Institute of Polymer Chemistry, College of Chemistry, Nankai University, Tianjin 300071, China
| | - Xiaotong Chen
- Key Laboratory of Functional Polymer Materials of Ministry of Education, Institute of Polymer Chemistry, College of Chemistry, Nankai University, Tianjin 300071, China
| | - Yue Zhou
- Key Laboratory of Functional Polymer Materials of Ministry of Education, Institute of Polymer Chemistry, College of Chemistry, Nankai University, Tianjin 300071, China
| | - Yue Zhao
- Key Laboratory of Functional Polymer Materials of Ministry of Education, Institute of Polymer Chemistry, College of Chemistry, Nankai University, Tianjin 300071, China
| | - Tiantian Song
- Key Laboratory of Functional Polymer Materials of Ministry of Education, Institute of Polymer Chemistry, College of Chemistry, Nankai University, Tianjin 300071, China
| | - Xiaoxue Wu
- Key Laboratory of Functional Polymer Materials of Ministry of Education, Institute of Polymer Chemistry, College of Chemistry, Nankai University, Tianjin 300071, China
| | - Weichao Shi
- Key Laboratory of Functional Polymer Materials of Ministry of Education, Institute of Polymer Chemistry, College of Chemistry, Nankai University, Tianjin 300071, China; Haihe Laboratory of Sustainable Chemical Transformations, Tianjin 300071, China.
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17
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Morzy D, Tekin C, Caroprese V, Rubio-Sánchez R, Di Michele L, Bastings MMC. Interplay of the mechanical and structural properties of DNA nanostructures determines their electrostatic interactions with lipid membranes. NANOSCALE 2023; 15:2849-2859. [PMID: 36688792 PMCID: PMC9909679 DOI: 10.1039/d2nr05368c] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Accepted: 01/16/2023] [Indexed: 05/27/2023]
Abstract
Nucleic acids and lipids function in close proximity in biological processes, as well as in nanoengineered constructs for therapeutic applications. As both molecules carry a rich charge profile, and frequently coexist in complex ionic solutions, the electrostatics surely play a pivotal role in interactions between them. Here we discuss how each component of a DNA/ion/lipid system determines its electrostatic attachment. We examine membrane binding of a library of DNA molecules varying from nanoengineered DNA origami through plasmids to short DNA domains, demonstrating the interplay between the molecular structure of the nucleic acid and the phase of lipid bilayers. Furthermore, the magnitude of DNA/lipid interactions is tuned by varying the concentration of magnesium ions in the physiologically relevant range. Notably, we observe that the structural and mechanical properties of DNA are critical in determining its attachment to lipid bilayers and demonstrate that binding is correlated positively with the size, and negatively with the flexibility of the nucleic acid. The findings are utilized in a proof-of-concept comparison of membrane interactions of two DNA origami designs - potential nanotherapeutic platforms - showing how the results can have a direct impact on the choice of DNA geometry for biotechnological applications.
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Affiliation(s)
- Diana Morzy
- Programmable Biomaterials Laboratory, Institute of Materials, School of Engineering, Ecole Polytechnique Fédérale Lausanne, Lausanne, 1015, Switzerland.
| | - Cem Tekin
- Programmable Biomaterials Laboratory, Institute of Materials, School of Engineering, Ecole Polytechnique Fédérale Lausanne, Lausanne, 1015, Switzerland.
| | - Vincenzo Caroprese
- Programmable Biomaterials Laboratory, Institute of Materials, School of Engineering, Ecole Polytechnique Fédérale Lausanne, Lausanne, 1015, Switzerland.
| | - Roger Rubio-Sánchez
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, London W12 0BZ, UK
- fabriCELL, Molecular Sciences Research Hub, Imperial College London, London W12 0BZ, UK
- Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, UK
| | - Lorenzo Di Michele
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, London W12 0BZ, UK
- fabriCELL, Molecular Sciences Research Hub, Imperial College London, London W12 0BZ, UK
| | - Maartje M C Bastings
- Programmable Biomaterials Laboratory, Institute of Materials, School of Engineering, Ecole Polytechnique Fédérale Lausanne, Lausanne, 1015, Switzerland.
- Interfaculty Bioengineering Institute, School of Engineering, Ecole Polytechnique Fédérale Lausanne, Lausanne, 1015, Switzerland
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18
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Zhang C, Kikushima K, Endo M, Kahyo T, Horikawa M, Matsudaira T, Tanaka T, Takanashi Y, Sato T, Takahashi Y, Xu L, Takayama N, Islam A, Mamun MA, Ozawa T, Setou M. Imaging and Manipulation of Plasma Membrane Fatty Acid Clusters Using TOF-SIMS Combined Optogenetics. Cells 2022; 12:cells12010010. [PMID: 36611804 PMCID: PMC9818728 DOI: 10.3390/cells12010010] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Revised: 12/16/2022] [Accepted: 12/18/2022] [Indexed: 12/24/2022] Open
Abstract
The plasma membrane (PM) serves multiple functions to support cell activities with its heterogeneous molecular distribution. Fatty acids (FAs) are hydrophobic components of the PM whose saturation and length determine the membrane's physical properties. The FA distribution contributes to the PM's lateral heterogeneity. However, the distribution of PM FAs is poorly understood. Here, we proposed the FA cluster hypothesis, which suggested that FAs on the PM exist as clusters. By the optogenetic tool translocating the endoplasmic reticulum (ER), we were able to manipulate the distribution of PM FAs. We used time-of-flight combined secondary ion mass spectrometry (TOF-SIMS) to image PM FAs and discovered that PM FAs were presented and distributed as clusters and are also manipulated as clusters. We also found the existence of multi-FA clusters formed by the colocalization of more than one FA. Our optogenetic tool also decreased the clustering degree of FA clusters and the formation probability of multi-FA clusters. This research opens up new avenues and perspectives to study PM heterogeneity from an FA perspective. This research also suggests a possible treatment for diseases caused by PM lipid aggregation and furnished a convenient tool for therapeutic development.
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Affiliation(s)
- Chi Zhang
- Department of Cellular and Molecular Anatomy, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu, Shizuoka 431-3192, Japan
| | - Kenji Kikushima
- Department of Cellular and Molecular Anatomy, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu, Shizuoka 431-3192, Japan
- International Mass Imaging Center, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu, Shizuoka 431-3192, Japan
| | - Mizuki Endo
- Department of Chemistry, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Tomoaki Kahyo
- Department of Cellular and Molecular Anatomy, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu, Shizuoka 431-3192, Japan
- International Mass Imaging Center, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu, Shizuoka 431-3192, Japan
| | - Makoto Horikawa
- Department of Cellular and Molecular Anatomy, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu, Shizuoka 431-3192, Japan
- International Mass Imaging Center, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu, Shizuoka 431-3192, Japan
- Hiroshima Research Center for Healthy Aging, Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8530, Japan
| | - Takaomi Matsudaira
- Foundation for Promotion of Material Science and Technology of Japan, 1-18-6 Kitami, Setagaya-ku, Tokyo 157-0067, Japan
| | - Tatsuya Tanaka
- Foundation for Promotion of Material Science and Technology of Japan, 1-18-6 Kitami, Setagaya-ku, Tokyo 157-0067, Japan
| | - Yusuke Takanashi
- Department of Cellular and Molecular Anatomy, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu, Shizuoka 431-3192, Japan
| | - Tomohito Sato
- Department of Cellular and Molecular Anatomy, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu, Shizuoka 431-3192, Japan
- International Mass Imaging Center, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu, Shizuoka 431-3192, Japan
| | - Yutaka Takahashi
- Department of Cellular and Molecular Anatomy, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu, Shizuoka 431-3192, Japan
- International Mass Imaging Center, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu, Shizuoka 431-3192, Japan
| | - Lili Xu
- Department of Cellular and Molecular Anatomy, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu, Shizuoka 431-3192, Japan
| | - Naoki Takayama
- Department of Cellular and Molecular Anatomy, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu, Shizuoka 431-3192, Japan
| | - Ariful Islam
- Department of Cellular and Molecular Anatomy, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu, Shizuoka 431-3192, Japan
| | - Md. Al Mamun
- Department of Cellular and Molecular Anatomy, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu, Shizuoka 431-3192, Japan
| | - Takeaki Ozawa
- Department of Chemistry, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Mitsutoshi Setou
- Department of Cellular and Molecular Anatomy, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu, Shizuoka 431-3192, Japan
- International Mass Imaging Center, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu, Shizuoka 431-3192, Japan
- Department of Systems Molecular Anatomy, Institute for Medical Photonics Research, Preeminent Medical Photonics Education & Research Center, 1-20-1 Handayama, Higashi-ku, Hamamatsu, Shizuoka 431-3192, Japan
- Correspondence:
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19
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Gurdap CO, Wedemann L, Sych T, Sezgin E. Influence of the extracellular domain size on the dynamic behavior of membrane proteins. Biophys J 2022; 121:3826-3836. [PMID: 36110044 PMCID: PMC9674980 DOI: 10.1016/j.bpj.2022.09.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Revised: 08/15/2022] [Accepted: 09/12/2022] [Indexed: 11/29/2022] Open
Abstract
The dynamic behavior of plasma membrane proteins mediates various cellular processes such as cellular motility, communication, and signaling. It is widely accepted that the dynamics of the membrane proteins is determined either by the interactions of the transmembrane domain with the surrounding lipids or by the interactions of the intracellular domain with cytosolic components such as cortical actin. Although initiation of different cellular signaling events at the plasma membrane has been attributed to the extracellular domain (ECD) properties recently, the impact of ECDs on the dynamic behavior of membrane proteins is rather unexplored. Here, we investigate how ECD properties influence protein dynamics in the lipid bilayer by reconstituting ECDs of different sizes or glycosylation in model membrane systems and analyzing ECD-driven protein sorting in lipid domains as well as protein mobility. Our data show that increasing the ECD mass or glycosylation leads to a decrease in ordered domain partitioning and diffusivity. Our data reconcile different mechanisms proposed for the initiation of cellular signaling by linking the ECD size of membrane proteins with their localization and diffusion dynamics in the plasma membrane.
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Affiliation(s)
- Cenk Onur Gurdap
- Science for Life Laboratory, Department of Women's and Children's Health, Karolinska Institutet, Solna, Sweden
| | - Linda Wedemann
- Science for Life Laboratory, Department of Women's and Children's Health, Karolinska Institutet, Solna, Sweden
| | - Taras Sych
- Science for Life Laboratory, Department of Women's and Children's Health, Karolinska Institutet, Solna, Sweden
| | - Erdinc Sezgin
- Science for Life Laboratory, Department of Women's and Children's Health, Karolinska Institutet, Solna, Sweden.
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20
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Ali AA, Bagheri Y, Tian Q, You M. Advanced DNA Zipper Probes for Detecting Cell Membrane Lipid Domains. NANO LETTERS 2022; 22:7579-7587. [PMID: 36084301 PMCID: PMC10368464 DOI: 10.1021/acs.nanolett.2c02605] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
The cell membrane is a complex mixture of lipids, proteins, and other components. By forming dynamic lipid domains, different membrane molecules can selectively interact with each other to control cell signaling. Herein, we report several new types of lipid-DNA conjugates, termed as "DNA zippers", which can be used to measure cell membrane dynamic interactions and the formation of lipid domains. Dependent on the choice of lipid moieties, cholesterol- and sphingomyelin-conjugated DNA zippers specifically locate in and detect membrane lipid-ordered domains, while in contrast, a tocopherol-DNA zipper can be applied for the selective imaging of lipid-disordered phases. These versatile and programmable probes can be further engineered into membrane competition assays to simultaneously detect multiple types of membrane dynamic interactions. These DNA zipper probes can be broadly used to study the correlation between lipid domains and various cellular processes, such as the epithelial-mesenchymal transition.
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Affiliation(s)
- Ahsan Ausaf Ali
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003, USA
| | - Yousef Bagheri
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003, USA
| | - Qian Tian
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003, USA
| | - Mingxu You
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003, USA
- Molecular and Cellular Biology Program, University of Massachusetts, Amherst, Massachusetts 01003, USA
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21
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Hoang KNL, McClain SM, Meyer SM, Jalomo CA, Forney NB, Murphy CJ. Site-selective modification of metallic nanoparticles. Chem Commun (Camb) 2022; 58:9728-9741. [PMID: 35975479 DOI: 10.1039/d2cc03603g] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Surface patterning of inorganic nanoparticles through site-selective functionalization with mixed-ligand shells or additional inorganic material is an intriguing approach to developing tailored nanomaterials with potentially novel and/or multifunctional properties. The unique physicochemical properties of such nanoparticles are likely to impact their behavior and functionality in biological environments, catalytic systems, and electronics applications, making it vital to understand how we can achieve and characterize such regioselective surface functionalization. This Feature Article will review methods by which chemists have selectively modified the surface of colloidal nanoparticles to obtain both two-sided Janus particles and nanoparticles with patchy or stripey mixed-ligand shells, as well as to achieve directed growth of mesoporous oxide materials and metals onto existing nanoparticle templates in a spatially and compositionally controlled manner. The advantages and drawbacks of various techniques used to characterize the regiospecificity of anisotropic surface coatings are discussed, as well as areas for improvement, and future directions for this field.
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Affiliation(s)
- Khoi Nguyen L Hoang
- Department of Chemistry, University of Illinois Urbana-Champaign, 600 South Mathews Avenue, Urbana, Illinois, 61801, USA.
| | - Sophia M McClain
- Department of Chemistry, University of Illinois Urbana-Champaign, 600 South Mathews Avenue, Urbana, Illinois, 61801, USA.
| | - Sean M Meyer
- Department of Chemistry, University of Illinois Urbana-Champaign, 600 South Mathews Avenue, Urbana, Illinois, 61801, USA.
| | - Catherine A Jalomo
- Department of Chemistry, University of Illinois Urbana-Champaign, 600 South Mathews Avenue, Urbana, Illinois, 61801, USA.
| | - Nathan B Forney
- Department of Chemistry, University of Illinois Urbana-Champaign, 600 South Mathews Avenue, Urbana, Illinois, 61801, USA.
| | - Catherine J Murphy
- Department of Chemistry, University of Illinois Urbana-Champaign, 600 South Mathews Avenue, Urbana, Illinois, 61801, USA.
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22
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Fifty Years of the Fluid–Mosaic Model of Biomembrane Structure and Organization and Its Importance in Biomedicine with Particular Emphasis on Membrane Lipid Replacement. Biomedicines 2022; 10:biomedicines10071711. [PMID: 35885016 PMCID: PMC9313417 DOI: 10.3390/biomedicines10071711] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 07/06/2022] [Accepted: 07/10/2022] [Indexed: 12/29/2022] Open
Abstract
The Fluid–Mosaic Model has been the accepted general or basic model for biomembrane structure and organization for the last 50 years. In order to establish a basic model for biomembranes, some general principles had to be established, such as thermodynamic assumptions, various molecular interactions, component dynamics, macromolecular organization and other features. Previous researchers placed most membrane proteins on the exterior and interior surfaces of lipid bilayers to form trimolecular structures or as lipoprotein units arranged as modular sheets. Such membrane models were structurally and thermodynamically unsound and did not allow independent lipid and protein lateral movements. The Fluid–Mosaic Membrane Model was the only model that accounted for these and other characteristics, such as membrane asymmetry, variable lateral movements of membrane components, cis- and transmembrane linkages and dynamic associations of membrane components into multimolecular complexes. The original version of the Fluid–Mosaic Membrane Model was never proposed as the ultimate molecular description of all biomembranes, but it did provide a basic framework for nanometer-scale biomembrane organization and dynamics. Because this model was based on available 1960s-era data, it could not explain all of the properties of various biomembranes discovered in subsequent years. However, the fundamental organizational and dynamic aspects of this model remain relevant to this day. After the first generation of this model was published, additional data on various structures associated with membranes were included, resulting in the addition of membrane-associated cytoskeletal, extracellular matrix and other structures, specialized lipid–lipid and lipid–protein domains, and other configurations that can affect membrane dynamics. The presence of such specialized membrane domains has significantly reduced the extent of the fluid lipid membrane matrix as first proposed, and biomembranes are now considered to be less fluid and more mosaic with some fluid areas, rather than a fluid matrix with predominantly mobile components. However, the fluid–lipid matrix regions remain very important in biomembranes, especially those involved in the binding and release of membrane lipid vesicles and the uptake of various nutrients. Membrane phospholipids can associate spontaneously to form lipid structures and vesicles that can fuse with various cellular membranes to transport lipids and other nutrients into cells and organelles and expel damaged lipids and toxic hydrophobic molecules from cells and tissues. This process and the clinical use of membrane phospholipid supplements has important implications for chronic illnesses and the support of healthy mitochondria, plasma membranes and other cellular membrane structures.
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23
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Videv P, Mladenova K, Andreeva TD, Park JH, Moskova-Doumanova V, Petrova SD, Doumanov JA. Cholesterol Alters the Phase Separation in Model Membranes Containing hBest1. Molecules 2022; 27:molecules27134267. [PMID: 35807512 PMCID: PMC9268032 DOI: 10.3390/molecules27134267] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2022] [Revised: 06/24/2022] [Accepted: 06/29/2022] [Indexed: 02/04/2023] Open
Abstract
Human retinal pigment epithelial (RPE) cells express the transmembrane Ca2+-dependent Cl− channel bestrophin-1 (hBest1) of the plasma membrane. Mutations in the hBest1 protein are associated with the development of distinct pathological conditions known as bestrophinopathies. The interactions between hBest1 and plasma membrane lipids (cholesterol (Chol), 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and sphingomyelin (SM)) determine its lateral organization and surface dynamics, i.e., their miscibility or phase separation. Using the surface pressure/mean molecular area (π/A) isotherms, hysteresis and compressibility moduli (Cs−1) of hBest1/POPC/Chol and hBest1/SM/Chol composite Langmuir monolayers, we established that the films are in an LE (liquid-expanded) or LE-LC (liquid-condensed) state, the components are well-mixed and the Ca2+ ions have a condensing effect on the surface molecular organization. Cholesterol causes a decrease in the elasticity of both films and a decrease in the ΔGmixπ values (reduction of phase separation) of hBest1/POPC/Chol films. For the hBest1/SM/Chol monolayers, the negative values of ΔGmixπ are retained and equalized with the values of ΔGmixπ in the hBest1/POPC/Chol films. Shifts in phase separation/miscibility by cholesterol can lead to changes in the structure and localization of hBest1 in the lipid rafts and its channel functions.
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Affiliation(s)
- Pavel Videv
- Faculty of Biology, Sofia University “St. Kliment Ohridski”, 8 Dragan Tzankov Str., 1164 Sofia, Bulgaria; (P.V.); (K.M.); (J.H.P.); (V.M.-D.); (S.D.P.)
| | - Kirilka Mladenova
- Faculty of Biology, Sofia University “St. Kliment Ohridski”, 8 Dragan Tzankov Str., 1164 Sofia, Bulgaria; (P.V.); (K.M.); (J.H.P.); (V.M.-D.); (S.D.P.)
| | - Tonya D. Andreeva
- Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 21, 1113 Sofia, Bulgaria;
- Faculty of Applied Chemistry, Reutlingen University, Alteburgstraße 150, 72762 Reutlingen, Germany
| | - Jong Hun Park
- Faculty of Biology, Sofia University “St. Kliment Ohridski”, 8 Dragan Tzankov Str., 1164 Sofia, Bulgaria; (P.V.); (K.M.); (J.H.P.); (V.M.-D.); (S.D.P.)
| | - Veselina Moskova-Doumanova
- Faculty of Biology, Sofia University “St. Kliment Ohridski”, 8 Dragan Tzankov Str., 1164 Sofia, Bulgaria; (P.V.); (K.M.); (J.H.P.); (V.M.-D.); (S.D.P.)
| | - Svetla D. Petrova
- Faculty of Biology, Sofia University “St. Kliment Ohridski”, 8 Dragan Tzankov Str., 1164 Sofia, Bulgaria; (P.V.); (K.M.); (J.H.P.); (V.M.-D.); (S.D.P.)
| | - Jordan A. Doumanov
- Faculty of Biology, Sofia University “St. Kliment Ohridski”, 8 Dragan Tzankov Str., 1164 Sofia, Bulgaria; (P.V.); (K.M.); (J.H.P.); (V.M.-D.); (S.D.P.)
- Correspondence: ; Tel.: +359-2-8167-262; Fax: +359-2-8656-641
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24
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Sezgin E. Giant plasma membrane vesicles to study plasma membrane structure and dynamics. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2022; 1864:183857. [PMID: 34990591 DOI: 10.1016/j.bbamem.2021.183857] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Revised: 12/25/2021] [Accepted: 12/27/2021] [Indexed: 10/19/2022]
Abstract
The plasma membrane (PM) is a highly heterogenous structure intertwined with the cortical actin cytoskeleton and extracellular matrix. This complex architecture makes it difficult to study the processes taking place at the PM. Model membrane systems that are simple mimics of the PM overcome this bottleneck and allow us to study the biophysical principles underlying the processes at the PM. Among them, cell-derived giant plasma membrane vesicles (GPMVs) are considered the most physiologically relevant system, retaining the compositional complexity of the PM to a large extent. GPMVs have become a key tool in membrane research in the last few years. In this review, I will provide a brief overview of this system, summarize recent applications and discuss the limitations.
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Affiliation(s)
- Erdinc Sezgin
- Science for Life Laboratory, Department of Women's and Children's Health, Karolinska Institutet, 17165 Solna, Sweden.
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25
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Schachter I, Paananen RO, Fábián B, Jurkiewicz P, Javanainen M. The Two Faces of the Liquid Ordered Phase. J Phys Chem Lett 2022; 13:1307-1313. [PMID: 35104407 PMCID: PMC8842317 DOI: 10.1021/acs.jpclett.1c03712] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Coexisting liquid ordered (Lo) and liquid disordered (Ld) lipid phases in synthetic and plasma membrane-derived vesicles are commonly used to model the heterogeneity of biological membranes, including their putative ordered rafts. However, raft-associated proteins exclusively partition to the Ld and not the Lo phase in these model systems. We believe that the difference stems from the different microscopic structures of the lipid rafts at physiological temperature and the Lo phase studied at room temperature. To probe this structural diversity across temperatures, we performed atomistic molecular dynamics simulations, differential scanning calorimetry, and fluorescence spectroscopy on Lo phase membranes. Our results suggest that raft-associated proteins are excluded from the Lo phase at room temperature due to the presence of a stiff, hexagonally packed lipid structure. This structure melts upon heating, which could lead to the preferential solvation of proteins by order-preferring lipids. This structural transition is manifested as a subtle crossover in membrane properties; yet, both temperature regimes still fulfill the definition of the Lo phase. We postulate that in the compositionally complex plasma membrane and in vesicles derived therefrom, both molecular structures can be present depending on the local lipid composition. These structural differences must be taken into account when using synthetic or plasma membrane-derived vesicles as a model for cellular membrane heterogeneity below the physiological temperature.
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Affiliation(s)
- Itay Schachter
- Institute
of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo nám. 542/2, CZ-16000 Prague 6, Czech Republic
- Institute
of Chemistry, the Fritz Haber Research Center, and the Harvey M. Kruger
Center for Nanoscience & Nanotechnology, The Hebrew University, Jerusalem 9190401, Israel
| | - Riku O. Paananen
- Department
of Chemistry, FI-00014 University of Helsinki, Helsinki, Finland
- Department
of Ophthalmology, FI-00014 University of
Helsinki and Helsinki University Hospital, Helsinki, Finland
| | - Balázs Fábián
- Institute
of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo nám. 542/2, CZ-16000 Prague 6, Czech Republic
| | - Piotr Jurkiewicz
- J.
Heyrovský Institute of Physical Chemistry of the Czech Academy
of Sciences, Dolejškova
2155/3, CZ-18223 Prague 8, Czech Republic
- E-mail:
| | - Matti Javanainen
- Institute
of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo nám. 542/2, CZ-16000 Prague 6, Czech Republic
- Institute
of Biotechnology, FI-00014 University of
Helsinki, Helsinki, Finland
- E-mail:
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26
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Sych T, Levental KR, Sezgin E. Lipid–Protein Interactions in Plasma Membrane Organization and Function. Annu Rev Biophys 2022; 51:135-156. [DOI: 10.1146/annurev-biophys-090721-072718] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Lipid–protein interactions in cells are involved in various biological processes, including metabolism, trafficking, signaling, host–pathogen interactions, and transmembrane transport. At the plasma membrane, lipid–protein interactions play major roles in membrane organization and function. Several membrane proteins have motifs for specific lipid binding, which modulate protein conformation and consequent function. In addition to such specific lipid–protein interactions, protein function can be regulated by the dynamic, collective behavior of lipids in membranes. Emerging analytical, biochemical, and computational technologies allow us to study the influence of specific lipid–protein interactions, as well as the collective behavior of membranes on protein function. In this article, we review the recent literature on lipid–protein interactions with a specific focus on the current state-of-the-art technologies that enable novel insights into these interactions. Expected final online publication date for the Annual Review of Biophysics, Volume 51 is May 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- Taras Sych
- Science for Life Laboratory, Department of Women's and Children's Health, Karolinska Institutet, Solna, Sweden;,
| | - Kandice R. Levental
- Department of Molecular Physiology and Biological Physics, Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, Virginia, USA
| | - Erdinc Sezgin
- Science for Life Laboratory, Department of Women's and Children's Health, Karolinska Institutet, Solna, Sweden;,
- MRC Human Immunology Unit, MRC Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, United Kingdom
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27
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Nicolson GL, Ferreira de Mattos G. A Brief Introduction to Some Aspects of the Fluid-Mosaic Model of Cell Membrane Structure and Its Importance in Membrane Lipid Replacement. MEMBRANES 2021; 11:947. [PMID: 34940448 PMCID: PMC8708848 DOI: 10.3390/membranes11120947] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Revised: 11/18/2021] [Accepted: 11/22/2021] [Indexed: 12/15/2022]
Abstract
Early cell membrane models placed most proteins external to lipid bilayers in trimolecular structures or as modular lipoprotein units. These thermodynamically untenable structures did not allow lipid lateral movements independent of membrane proteins. The Fluid-Mosaic Membrane Model accounted for these and other properties, such as membrane asymmetry, variable lateral mobilities of membrane components and their associations with dynamic complexes. Integral membrane proteins can transform into globular structures that are intercalated to various degrees into a heterogeneous lipid bilayer matrix. This simplified version of cell membrane structure was never proposed as the ultimate biomembrane description, but it provided a basic nanometer scale framework for membrane organization. Subsequently, the structures associated with membranes were considered, including peripheral membrane proteins, and cytoskeletal and extracellular matrix components that restricted lateral mobility. In addition, lipid-lipid and lipid-protein membrane domains, essential for cellular signaling, were proposed and eventually discovered. The presence of specialized membrane domains significantly reduced the extent of the fluid lipid matrix, so membranes have become more mosaic with some fluid areas over time. However, the fluid regions of membranes are very important in lipid transport and exchange. Various lipid globules, droplets, vesicles and other membranes can fuse to incorporate new lipids or expel damaged lipids from membranes, or they can be internalized in endosomes that eventually fuse with other internal vesicles and membranes. They can also be externalized in a reverse process and released as extracellular vesicles and exosomes. In this Special Issue, the use of membrane phospholipids to modify cellular membranes in order to modulate clinically relevant host properties is considered.
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Affiliation(s)
- Garth L. Nicolson
- Department of Molecular Pathology, The Institute for Molecular Medicine, Huntington Beach, CA 92647, USA
| | - Gonzalo Ferreira de Mattos
- Laboratory of Ion Channels, Biological Membranes and Cell Signaling, Department of Biophysics, Facultad de Medicina, Universidad de la República, Montevideo 11600, Uruguay;
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