1
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Kim S. All-Atom Membrane Builder via Multiscale Simulation. J Chem Inf Model 2024. [PMID: 39250520 DOI: 10.1021/acs.jcim.4c01059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/11/2024]
Abstract
I present an automated and flexible tool designed for constructing bilayer membranes at all-atom (AA) resolution. The builder initiates the construction and equilibration of bilayer membranes at Martini coarse-grained (CG) resolution, followed by resolution enhancement to the atomic level using the accompanying backmapping tool. Notably, this tool enables users to create bilayer membranes with user-defined lipid compositions and protein structures, while also offering the flexibility to accommodate new lipid types. To assess the simplicity and robustness of the tool, I demonstrate the construction of several membranes incorporating protein structures. The tool is freely available at github.com/ksy141/mstool.
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Affiliation(s)
- Siyoung Kim
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, United States
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2
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Holzhütter HG. Dynamical modelling of lipid droplet formation suggests a key function of membrane phospholipids. FEBS J 2024. [PMID: 39132700 DOI: 10.1111/febs.17238] [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: 03/15/2024] [Revised: 06/10/2024] [Accepted: 07/23/2024] [Indexed: 08/13/2024]
Abstract
Cells store triacylglycerol (TAG) within lipid droplets (LDs). A dynamic model describing complete LD formation at the endoplasmic reticulum (ER) membrane does not yet exist. A biochemical-biophysical model of LD synthesis is proposed. It describes the time-dependent accumulation of TAG in the ER membrane as the formation of a potential LD (pLD) bounded by spherical caps of the inner and outer monolayers of the membrane. The expansion rate of the pLD depends on the TAG supply, the elastic properties of the ER membrane, and the recruitment of phospholipids (PLs) to the cap-covering monolayers. Model simulations provided the following insights: (a) Marginal differences in the surface tension of the cap monolayers are sufficient to fully drive the expansion of the pLD towards the cytosol or lumen. (b) Selective reduction of PL supply to the luminal monolayer ensures stable formation of cytosolic LDs, irrespective of variations in the elasto-mechanical properties of the ER membrane. (c) The rate of TAG supply to the cytosolic monolayer has a major effect on the size and maturation time of LDs but has no significant effect on the TAG export per individual LD. The recruitment of additional PLs to the cap monolayers of pLDs critically controls the budding direction, size, and maturation time of LDs. The ability of cells to acquire additional LD initiation sites appears to be key to coping with acutely high levels of potentially toxic free fatty acids.
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Affiliation(s)
- Hermann-Georg Holzhütter
- Institute of Biochemistry, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Germany
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3
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Pradel B, Cantaloube G, Villares M, Deffieu MS, Robert-Hebmann V, Lucansky V, Faure M, Chazal N, Gaudin R, Espert L. LC3B conjugation machinery promotes autophagy-independent HIV-1 entry in CD4 + T lymphocytes. Autophagy 2024; 20:1825-1836. [PMID: 38566318 PMCID: PMC11262235 DOI: 10.1080/15548627.2024.2338573] [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: 08/21/2023] [Accepted: 03/29/2024] [Indexed: 04/04/2024] Open
Abstract
HIV-1 entry into CD4+ T lymphocytes relies on the viral and cellular membranes' fusion, leading to viral capsid delivery in the target cell cytoplasm. Atg8/LC3B conjugation to lipids, process named Atg8ylation mainly studied in the context of macroautophagy/autophagy, occurs transiently in the early stages of HIV-1 replication in CD4+ T lymphocytes. Despite numerous studies investigating the HIV-1-autophagy interplays, the Atg8ylation impact in these early stages of infection remains unknown. Here we found that HIV-1 exposure leads to the rapid LC3B enrichment toward the target cell plasma membrane, in close proximity with the incoming viral particles. Furthermore, we demonstrated that Atg8ylation is a key event facilitating HIV-1 entry in target CD4+ T cells. Interestingly, this effect is independent of canonical autophagy as ATG13 silencing does not prevent HIV-1 entry. Together, our results provide an unconventional role of LC3B conjugation subverted by HIV-1 to achieve a critical step of its replication cycle.Abbreviations: BafA1: bafilomycin A1; BlaM: beta-lactamase; CD4+ TL: CD4+ T lymphocytes; PtdIns3K-BECN1 complex: BECN1-containing class III phosphatidylinositol 3-kinase complex; Env: HIV-1 envelope glycoproteins; HIV-1: type 1 human immunodeficiency virus; PM: plasma membrane; PtdIns3P: phosphatidylinositol-3-phosphate; VLP: virus-like particle.
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Affiliation(s)
- Baptiste Pradel
- University of Montpellier, CNRS, Institut de Recherche en Infectiologie de Montpellier (IRIM), Montpellier, France
| | - Guilhem Cantaloube
- University of Montpellier, CNRS, Institut de Recherche en Infectiologie de Montpellier (IRIM), Montpellier, France
| | - Marie Villares
- University of Montpellier, CNRS, Institut de Recherche en Infectiologie de Montpellier (IRIM), Montpellier, France
| | - Maïka S. Deffieu
- University of Montpellier, CNRS, Institut de Recherche en Infectiologie de Montpellier (IRIM), Montpellier, France
| | - Véronique Robert-Hebmann
- University of Montpellier, CNRS, Institut de Recherche en Infectiologie de Montpellier (IRIM), Montpellier, France
| | - Vincent Lucansky
- University of Montpellier, CNRS, Institut de Recherche en Infectiologie de Montpellier (IRIM), Montpellier, France
- Jessenius Faculty of Medicine in Martin (JFMED CU), Department of Pathophysiology, Comenius University in Bratislava, Martin, Slovakia
| | - Mathias Faure
- CIRI, University of Lyon, Inserm U1111, Claude Bernard University Lyon 1, CNRS, UMR5308, ENS de Lyon, Lyon, France
| | - Nathalie Chazal
- University of Montpellier, CNRS, Institut de Recherche en Infectiologie de Montpellier (IRIM), Montpellier, France
| | - Raphaël Gaudin
- University of Montpellier, CNRS, Institut de Recherche en Infectiologie de Montpellier (IRIM), Montpellier, France
| | - Lucile Espert
- University of Montpellier, CNRS, Institut de Recherche en Infectiologie de Montpellier (IRIM), Montpellier, France
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4
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Uchiumi O, Zou J, Yamaki S, Hori Y, Ono M, Yamamoto R, Kato N. Disruption of sphingomyelin synthase 2 gene alleviates cognitive impairment in a mouse model of Alzheimer's disease. Brain Res 2024; 1835:148934. [PMID: 38609029 DOI: 10.1016/j.brainres.2024.148934] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2024] [Revised: 03/28/2024] [Accepted: 04/09/2024] [Indexed: 04/14/2024]
Abstract
The membrane raft accommodates the key enzymes synthesizing amyloid β (Aβ). One of the two characteristic components of the membrane raft, cholesterol, is well known to promote the key enzymes that produce amyloid-β (Aβ) and exacerbate Alzheimer's disease (AD) pathogenesis. Given that the raft is a physicochemical platform for the sound functioning of embedded bioactive proteins, the other major lipid component sphingomyelin may also be involved in AD. Here we knocked out the sphingomyelin synthase 2 gene (SMS2) in 3xTg AD model mice by hybridization, yielding SMS2KO mice (4S mice). The novel object recognition test in 9/10-month-old 4S mice showed that cognitive impairment in 3xTg mice was alleviated by SMS2KO, though performance in the Morris water maze (MWM) was not improved. The tail suspension test detected a depressive trait in 4S mice, which may have hindered the manifestation of performance in the wet, stressful environment of MWM. In the hippocampal CA1, hyperexcitability in 3xTg was also found alleviated by SMS2KO. In the hippocampal dentate gyrus of 4S mice, the number of neurons positive with intracellular Aβ or its precursor proteins, the hallmark of young 3xTg mice, is reduced to one-third, suggesting an SMS2KO-led suppression of syntheses of those peptides in the dentate gyrus. Although we previously reported that large-conductance calcium-activated potassium (BK) channels are suppressed in 3xTg mice and their recovery relates to cognitive amelioration, no changes occurred by hybridization. Sphingomyelin in the membrane raft may serve as a novel target for AD drugs.
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Affiliation(s)
- Osamu Uchiumi
- Department of Physiology, Kanazawa Medical University, Ishikawa 920-0293, Japan
| | - Jingyu Zou
- Department of Physiology, Kanazawa Medical University, Ishikawa 920-0293, Japan; First Affiliated Hospital, China Medical University, Shenyang 110001, China
| | - Sachiko Yamaki
- Department of Physiology, Kanazawa Medical University, Ishikawa 920-0293, Japan
| | - Yoshie Hori
- Department of Physiology, Kanazawa Medical University, Ishikawa 920-0293, Japan
| | - Munenori Ono
- Department of Physiology, Kanazawa Medical University, Ishikawa 920-0293, Japan
| | - Ryo Yamamoto
- Department of Physiology, Kanazawa Medical University, Ishikawa 920-0293, Japan
| | - Nobuo Kato
- Department of Physiology, Kanazawa Medical University, Ishikawa 920-0293, Japan.
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5
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Prokisch S, Büttner S. Partitioning into ER membrane microdomains impacts autophagic protein turnover during cellular aging. Sci Rep 2024; 14:13653. [PMID: 38871812 DOI: 10.1038/s41598-024-64493-8] [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: 09/29/2023] [Accepted: 06/09/2024] [Indexed: 06/15/2024] Open
Abstract
Eukaryotic membranes are compartmentalized into distinct micro- and nanodomains that rearrange dynamically in response to external and internal cues. This lateral heterogeneity of the lipid bilayer and associated clustering of distinct membrane proteins contribute to the spatial organization of numerous cellular processes. Here, we show that membrane microdomains within the endoplasmic reticulum (ER) of yeast cells are reorganized during metabolic reprogramming and aging. Using biosensors with varying transmembrane domain length to map lipid bilayer thickness, we demonstrate that in young cells, microdomains of increased thickness mainly exist within the nuclear ER, while progressing cellular age drives the formation of numerous microdomains specifically in the cortical ER. Partitioning of biosensors with long transmembrane domains into these microdomains increased protein stability and prevented autophagic removal. In contrast, reporters with short transmembrane domains progressively accumulated at the membrane contact site between the nuclear ER and the vacuole, the so-called nucleus-vacuole junction (NVJ), and were subjected to turnover via selective microautophagy occurring specifically at these sites. Reporters with long transmembrane domains were excluded from the NVJ. Our data reveal age-dependent rearrangement of the lateral organization of the ER and establish transmembrane domain length as a determinant of membrane contact site localization and autophagic degradation.
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Affiliation(s)
- Simon Prokisch
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, 10691, Stockholm, Sweden
| | - Sabrina Büttner
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, 10691, Stockholm, Sweden.
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6
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Huster D, Maiti S, Herrmann A. Phospholipid Membranes as Chemically and Functionally Tunable Materials. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2312898. [PMID: 38456771 DOI: 10.1002/adma.202312898] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Revised: 02/12/2024] [Indexed: 03/09/2024]
Abstract
The sheet-like lipid bilayer is the fundamental structural component of all cell membranes. Its building blocks are phospholipids and cholesterol. Their amphiphilic structure spontaneously leads to the formation of a bilayer in aqueous environment. Lipids are not just structural elements. Individual lipid species, the lipid membrane structure, and lipid dynamics influence and regulate membrane protein function. An exciting field is emerging where the membrane-associated material properties of different bilayer systems are used in designing innovative solutions for widespread applications across various fields, such as the food industry, cosmetics, nano- and biomedicine, drug storage and delivery, biotechnology, nano- and biosensors, and computing. Here, the authors summarize what is known about how lipids determine the properties and functions of biological membranes and how this has been or can be translated into innovative applications. Based on recent progress in the understanding of membrane structure, dynamics, and physical properties, a perspective is provided on how membrane-controlled regulation of protein functions can extend current applications and even offer new applications.
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Affiliation(s)
- Daniel Huster
- Institute of Medical Physics and Biophysics, University of Leipzig, Härtelstr. 16/18, D-04107, Leipzig, Germany
| | - Sudipta Maiti
- Department of Chemical Sciences, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai, 400 005, India
| | - Andreas Herrmann
- Freie Universität Berlin, Department Chemistry and Biochemistry, SupraFAB, Altensteinstr. 23a, D-14195, Berlin, Germany
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7
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Liu Q, Wang T, Ke M, Qian C, Li J, Huang X, Gao Z, Chen X, Tu T. UV-B Radiation Disrupts Membrane Lipid Organization and Suppresses Protein Mobility of GmNARK in Arabidopsis. PLANTS (BASEL, SWITZERLAND) 2024; 13:1536. [PMID: 38891343 PMCID: PMC11174901 DOI: 10.3390/plants13111536] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2024] [Revised: 05/23/2024] [Accepted: 05/30/2024] [Indexed: 06/21/2024]
Abstract
While it is well known that plants interpret UV-B as an environmental cue and a potential stressor influencing their growth and development, the specific effects of UV-B-induced oxidative stress on the dynamics of membrane lipids and proteins remain underexplored. Here, we demonstrate that UV-B exposure notably increases the formation of ordered lipid domains on the plasma membrane (PM) and significantly alters the behavior of the Glycine max nodule autoregulation receptor kinase (GmNARK) protein in Arabidopsis leaves. The GmNARK protein was located on the PM and accumulated as small particles in the cytoplasm. We found that UV-B irradiation interrupted the lateral diffusion of GmNARK proteins on the PM. Furthermore, UV-B light decreases the efficiency of surface molecule internalization by clathrin-mediated endocytosis (CME). In brief, UV-B irradiation increased the proportion of the ordered lipid phase and disrupted clathrin-dependent endocytosis; thus, the endocytic trafficking and lateral mobility of GmNARK protein on the plasma membrane are crucial for nodule formation tuning. Our results revealed a novel role of low-intensity UV-B stress in altering the organization of the plasma membrane and the dynamics of membrane-associated proteins.
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Affiliation(s)
- Qiulin Liu
- Fujian Provincial Key Laboratory of Haixia Applied Plant Systems Biology, College of Life Science, Fujian Agriculture and Forestry University, Fuzhou 350002, China; (Q.L.); (T.W.); (M.K.); (Z.G.)
- Horticultural Plant Biology and Metabolomics Center, Haixia Institute of Science and Technology, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Tianyu Wang
- Fujian Provincial Key Laboratory of Haixia Applied Plant Systems Biology, College of Life Science, Fujian Agriculture and Forestry University, Fuzhou 350002, China; (Q.L.); (T.W.); (M.K.); (Z.G.)
- Horticultural Plant Biology and Metabolomics Center, Haixia Institute of Science and Technology, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Meiyu Ke
- Fujian Provincial Key Laboratory of Haixia Applied Plant Systems Biology, College of Life Science, Fujian Agriculture and Forestry University, Fuzhou 350002, China; (Q.L.); (T.W.); (M.K.); (Z.G.)
- Horticultural Plant Biology and Metabolomics Center, Haixia Institute of Science and Technology, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Chongzhen Qian
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen 361102, China; (C.Q.); (X.H.)
| | - Jiejie Li
- Beijing Key Laboratory of Gene Resource and Molecular Development, College of Life Science, Beijing Normal University, Beijing 100875, China;
| | - Xi Huang
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen 361102, China; (C.Q.); (X.H.)
| | - Zhen Gao
- Fujian Provincial Key Laboratory of Haixia Applied Plant Systems Biology, College of Life Science, Fujian Agriculture and Forestry University, Fuzhou 350002, China; (Q.L.); (T.W.); (M.K.); (Z.G.)
- Horticultural Plant Biology and Metabolomics Center, Haixia Institute of Science and Technology, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Xu Chen
- Horticultural Plant Biology and Metabolomics Center, Haixia Institute of Science and Technology, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Tianli Tu
- Horticultural Plant Biology and Metabolomics Center, Haixia Institute of Science and Technology, Fujian Agriculture and Forestry University, Fuzhou 350002, China
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8
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Zhao L, Wang Y, Zhang Y, Chen H, Sun F. Dynamic Simulations of Interaction of the PEG-DPPE Micelle-Encapsulated Short-Chain Ceramides with the Raft-Included Membrane. J Chem Inf Model 2024; 64:3874-3883. [PMID: 38652138 DOI: 10.1021/acs.jcim.4c00170] [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: 04/25/2024]
Abstract
The lipid raft subdomains in cancer cell membranes play a key role in signal transduction, biomolecule recruitment, and drug transmembrane transport. Augmented membrane rigidity due to the formation of a lipid raft is unfavorable for the entry of drugs, a limiting factor in clinical oncology. The short-chain ceramide (CER) has been reported to promote drug entry into membranes and disrupt lipid raft formation, but the underlying mechanism is not well understood. We recently explored the carrier-membrane fusion dynamics of PEG-DPPE micelles in delivering doxorubicin (DOX). Based on the phase-segregated membrane model composed of DPPC/DIPC/CHOL/GM1/PIP2, we aim to explore the dynamic mechanism of the PEG-DPPE micelle-encapsulating DOXs in association with the raft-included cell membrane modulated by C8 acyl tail CERs. The results show that the lipid raft remains integrated and DOX-resistant subjected to free DOXs and the micelle-encapsulating ones. Addition of CERs disorganizes the lipid raft by pushing CHOL aside from DPPC. It subsequently allows for a good permeability for PEG-DPPE micelle-encapsulated DOXs, which penetrate deeper as CER concentration increases. GM1 is significant in guiding drugs' redistributing between bilayer phases, and the anionic PIP2 further helps DOXs attain the inner bilayer surface. These results elaborate on the perturbing effect of CERs on lipid raft stability, which provides a new comprehensive approach for further design of drug delivery systems.
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Affiliation(s)
- Lina Zhao
- Key Laboratory of Molecular Biophysics, Hebei Province, Institute of Biophysics, School of Health Science & Biomedical Engineering, Hebei University of Technology, Tianjin 300401, China
| | - Yanjiao Wang
- Key Laboratory of Molecular Biophysics, Hebei Province, Institute of Biophysics, School of Health Science & Biomedical Engineering, Hebei University of Technology, Tianjin 300401, China
| | - Yi Zhang
- Key Laboratory of Molecular Biophysics, Hebei Province, Institute of Biophysics, School of Health Science & Biomedical Engineering, Hebei University of Technology, Tianjin 300401, China
| | - Hao Chen
- Key Laboratory of Molecular Biophysics, Hebei Province, Institute of Biophysics, School of Health Science & Biomedical Engineering, Hebei University of Technology, Tianjin 300401, China
| | - Fude Sun
- Key Laboratory of Molecular Biophysics, Hebei Province, Institute of Biophysics, School of Health Science & Biomedical Engineering, Hebei University of Technology, Tianjin 300401, China
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9
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Kashnik AS, Baranov DS, Dzuba SA. Spatial Arrangement of the Drug Ibuprofen in a Model Membrane in the Presence of Lipid Rafts. J Phys Chem B 2024; 128:3652-3661. [PMID: 38576273 DOI: 10.1021/acs.jpcb.4c01507] [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: 04/06/2024]
Abstract
Many pharmaceutical drugs are known to interact with lipid membranes through nonspecific molecular interactions, which affect their therapeutic effect. Ibuprofen is a nonsteroidal anti-inflammatory drug (NSAID) and one of the most commonly prescribed. In the presence of cholesterol, lipid bilayers can separate into nanoscale liquid-disordered and liquid-ordered structures, the latter known as lipid rafts. Here, we study spin-labeled ibuprofen (ibuprofen-SL) in the model membrane consisting of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), and cholesterol in the molar ratio of (0.5-0.5xchol)/(0.5-0.5xchol)/xchol. Electron paramagnetic resonance (EPR) spectroscopy is employed, along with its pulsed version of double electron-electron resonance (DEER, also known as PELDOR). The data obtained indicate lateral lipid-mediated clustering of ibuprofen-SL molecules with a local surface density noticeably larger than that expected for random lateral distribution. In the absence of cholesterol, the data can be interpreted as indicating alternating clustering in two opposing leaflets of the bilayer. In the presence of cholesterol, for xchol ≥ 20 mol %, the results show that ibuprofen-SL molecules have a quasi-regular lateral distribution, with a "superlattice" parameter of ∼3.0 nm. This regularity can be explained by the entrapment of ibuprofen-SL molecules by lipid rafts known to exist in this system with the additional assumption that lipid rafts have a nanoscale substructure.
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Affiliation(s)
- Anna S Kashnik
- Institute of Chemical Kinetics and Combustion, Russian Academy of Sciences, Novosibirsk 630090, Russia
| | - Denis S Baranov
- Institute of Chemical Kinetics and Combustion, Russian Academy of Sciences, Novosibirsk 630090, Russia
| | - Sergei A Dzuba
- Institute of Chemical Kinetics and Combustion, Russian Academy of Sciences, Novosibirsk 630090, Russia
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10
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An K, Qiao Q, Zhou W, Jiang W, Li J, Xu Z. Stable Super-Resolution Imaging of Cell Membrane Nanoscale Subcompartment Dynamics with a Buffering Cyanine Dye. Anal Chem 2024; 96:5985-5991. [PMID: 38557031 DOI: 10.1021/acs.analchem.4c00342] [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: 04/04/2024]
Abstract
Super-resolution fluorescence imaging is a crucial method for visualizing the dynamics of the cell membrane involved in various physiological and pathological processes. This requires bright fluorescent dyes with excellent photostability and labeling stability to enable long-term imaging. In this context, we introduce a buffering-strategy-based cyanine dye, SA-Cy5, designed to identify and label carbonic anhydrase IX (CA IX) located in the cell membrane. The unique feature of SA-Cy5 lies in its ability to overcome photobleaching. When the dye on the cell membrane undergoes photobleaching, it is rapidly replaced by an intact probe from the buffer pool outside the cell membrane. This dynamic replacement ensures that the fluorescence intensity on the cell membrane remains stable over time. Under the super-resolution structured illumination microscopy (SIM), the cell membrane can be continuously imaged for 60 min with a time resolution of 20 s. This extended imaging period allows for the observation of substructural dynamics of the cell membrane, including the growth and fusion of filamentous pseudopodia and the fusion of vesicles. Additionally, this buffering strategy introduces a novel approach to address the issue of poor photostability associated with the cyanine dyes.
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Affiliation(s)
- Kai An
- CAS Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Qinglong Qiao
- CAS Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, China
| | - Wei Zhou
- CAS Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, China
| | - Wenchao Jiang
- CAS Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jin Li
- CAS Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, China
| | - Zhaochao Xu
- CAS Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, China
- University of Chinese Academy of Sciences, Beijing 100049, China
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11
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Fellows AP, John B, Wolf M, Thämer M. Spiral packing and chiral selectivity in model membranes probed by phase-resolved sum-frequency generation microscopy. Nat Commun 2024; 15:3161. [PMID: 38605056 PMCID: PMC11009297 DOI: 10.1038/s41467-024-47573-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Accepted: 04/04/2024] [Indexed: 04/13/2024] Open
Abstract
Since the lipid raft model was developed at the end of the last century, it became clear that the specific molecular arrangements of phospholipid assemblies within a membrane have profound implications in a vast range of physiological functions. Studies of such condensed lipid islands in model systems using fluorescence and Brewster angle microscopies have shown a wide range of sizes and morphologies, with suggestions of substantial in-plane molecular anisotropy and mesoscopic structural chirality. Whilst these variations can significantly alter many membrane properties including its fluidity, permeability and molecular recognition, the details of the in-plane molecular orientations underlying these traits remain largely unknown. Here, we use phase-resolved sum-frequency generation microscopy on model membranes of mixed chirality phospholipid monolayers to fully determine the three-dimensional molecular structure of the constituent micron-scale condensed domains. We find that the domains possess curved molecular directionality with spiralling mesoscopic packing, where both the molecular and spiral turning directions depend on the lipid chirality, but form structures clearly deviating from mirror symmetry for different enantiomeric mixtures. This demonstrates strong enantioselectivity in the domain growth process and indicates fundamental thermodynamic differences between homo- and heterochiral membranes, which may be relevant in the evolution of homochirality in all living organisms.
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Affiliation(s)
| | - Ben John
- Fritz-Haber-Institute of the Max-Planck-Society, Berlin, Germany
| | - Martin Wolf
- Fritz-Haber-Institute of the Max-Planck-Society, Berlin, Germany
| | - Martin Thämer
- Fritz-Haber-Institute of the Max-Planck-Society, Berlin, Germany.
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12
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Ozturk TN, König M, Carpenter TS, Pedersen KB, Wassenaar TA, Ingólfsson HI, Marrink SJ. Building complex membranes with Martini 3. Methods Enzymol 2024; 701:237-285. [PMID: 39025573 DOI: 10.1016/bs.mie.2024.03.010] [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] [Indexed: 07/20/2024]
Abstract
The Martini model is a popular force field for coarse-grained simulations. Membranes have always been at the center of its development, with the latest version, Martini 3, showing great promise in capturing more and more realistic behavior. In this chapter we provide a step-by-step tutorial on how to construct starting configurations, run initial simulations and perform dedicated analysis for membrane-based systems of increasing complexity, including leaflet asymmetry, curvature gradients and embedding of membrane proteins.
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Affiliation(s)
- Tugba Nur Ozturk
- Biosciences and Biotechnology Division, Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA, United States
| | - Melanie König
- Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, The Netherlands
| | - Timothy S Carpenter
- Biosciences and Biotechnology Division, Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA, United States
| | | | - Tsjerk A Wassenaar
- Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, The Netherlands; Institute for Life Science and Technology, Hanze University of Applied Sciences, Groningen, The Netherlands
| | - Helgi I Ingólfsson
- Biosciences and Biotechnology Division, Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA, United States.
| | - Siewert J Marrink
- Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, The Netherlands.
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13
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Saha R, Poduval P, Baratam K, Nagesh J, Srivastava A. Membrane Catalyzed Formation of Nucleotide Clusters and Their Role in the Origins of Life: Insights from Molecular Simulations and Lattice Modeling. J Phys Chem B 2024; 128:3121-3132. [PMID: 38518175 DOI: 10.1021/acs.jpcb.3c08061] [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: 03/24/2024]
Abstract
One of the mysteries in studying the molecular "Origin of Life" is the emergence of RNA and RNA-based life forms, where nonenzymatic polymerization of nucleotides is a crucial hypothesis in formation of large RNA chains. The nonenzymatic polymerization can be mediated by various environmental settings, such as cycles of hydration and dehydration, temperature variations, and proximity to a variety of organizing matrices, such as clay, salt, fatty acids, lipid membrane, and mineral surface. In this work, we explore the influence of different phases of the lipid membrane toward nucleotide organization and polymerization in a simulated prebiotic setting. Our molecular simulations quantify the localization propensity of a mononucleotide, uridine monophosphate (UMP), in distinct membrane settings. We perform all-atom molecular dynamics (MD) simulations to estimate the role of the monophasic and biphasic membranes in modifying the behavior of UMPs localization and their clustering mechanism. Based on the interaction energy of mononucleotides with the membrane and their diffusion profile from our MD calculations, we developed a lattice-based model to explore the thermodynamic limits of the observations made from the MD simulations. The mathematical model substantiates our hypothesis that the lipid layers can act as unique substrates for "catalyzing" polymerization of mononucleotides due to the inherent spatiotemporal heterogeneity and phase change behavior.
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Affiliation(s)
- Rajlaxmi Saha
- Department of Biological Sciences, Indian Institute of Science Education and Research, Kolkata 741246, India
| | - Prathyush Poduval
- Department of Physics, Indian Institute of Science, Bangalore, Karnataka 560012, India
| | - Krishnakanth Baratam
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, Karnataka 560012, India
| | - Jayashree Nagesh
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore, Karnataka 560012, India
| | - Anand Srivastava
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, Karnataka 560012, India
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14
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Bernard C, Carotenuto AR, Pugno NM, Fraldi M, Deseri L. Modelling lipid rafts formation through chemo-mechanical interplay triggered by receptor-ligand binding. Biomech Model Mechanobiol 2024; 23:485-505. [PMID: 38060155 PMCID: PMC10963483 DOI: 10.1007/s10237-023-01787-2] [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: 07/28/2023] [Accepted: 10/21/2023] [Indexed: 12/08/2023]
Abstract
Cell membranes, mediator of many biological mechanisms from adhesion and metabolism up to mutation and infection, are highly dynamic and heterogeneous environments exhibiting a strong coupling between biochemical events and structural re-organisation. This involves conformational changes induced, at lower scales, by lipid order transitions and by the micro-mechanical interplay of lipids with transmembrane proteins and molecular diffusion. Particular attention is focused on lipid rafts, ordered lipid microdomains rich of signalling proteins, that co-localise to enhance substance trafficking and activate different intracellular biochemical pathways. In this framework, the theoretical modelling of the dynamic clustering of lipid rafts implies a full multiphysics coupling between the kinetics of phase changes and the mechanical work performed by transmembrane proteins on lipids, involving the bilayer elasticity. This mechanism produces complex interspecific dynamics in which membrane stresses and chemical potentials do compete by determining different morphological arrangements, alteration in diffusive walkways and coalescence phenomena, with a consequent influence on both signalling potential and intracellular processes. Therefore, after identifying the leading chemo-mechanical interactions, the present work investigates from a modelling perspective the spatio-temporal evolution of raft domains to theoretically explain co-localisation and synergy between proteins' activation and raft formation, by coupling diffusive and mechanical phenomena to observe different morphological patterns and clustering of ordered lipids. This could help to gain new insights into the remodelling of cell membranes and could potentially suggest mechanically based strategies to control their selectivity, by orienting intracellular functions and mechanotransduction.
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Affiliation(s)
- Chiara Bernard
- Department of Civil, Environmental and Mechanical Engineering, University of Trento, Trento, Italy
| | - Angelo Rosario Carotenuto
- Department of Structures for Engineering and Architecture, University of Naples "Federico II", Naples, Italy
- Laboratory of Integrated Mechanics and Imaging for Testing and Simulation (LIMITS), University of Naples "Federico II", Naples, Italy
| | - Nicola Maria Pugno
- Department of Civil, Environmental and Mechanical Engineering, University of Trento, Trento, Italy
- Laboratory for Bioinspired, Bionic, Nano, Meta Materials and Mechanics, University of Trento, Trento, Italy
- School of Engineering and Materials Science, Queen Mary University of London, London, UK
| | - Massimiliano Fraldi
- Department of Structures for Engineering and Architecture, University of Naples "Federico II", Naples, Italy
- Laboratory of Integrated Mechanics and Imaging for Testing and Simulation (LIMITS), University of Naples "Federico II", Naples, Italy
- Département de Physique, LPENS, École Normale Supérieure-PSL, Paris, France
| | - Luca Deseri
- Department of Civil, Environmental and Mechanical Engineering, University of Trento, Trento, Italy.
- Department of Mechanical Engineering and Material Sciences, MEMS-SSoE, University of Pittsburgh, Pittsburgh, USA.
- Department of Civil and Environmental Engineering, Carnegie Mellon University, Pittsburgh, USA.
- Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, USA.
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15
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Wang Z, Li W, Jiang Y, Park J, Gonzalez KM, Wu X, Zhang QY, Lu J. Cholesterol-modified sphingomyelin chimeric lipid bilayer for improved therapeutic delivery. Nat Commun 2024; 15:2073. [PMID: 38453918 PMCID: PMC10920917 DOI: 10.1038/s41467-024-46331-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2023] [Accepted: 02/22/2024] [Indexed: 03/09/2024] Open
Abstract
Cholesterol (Chol) fortifies packing and reduces fluidity and permeability of the lipid bilayer in vesicles (liposomes)-mediated drug delivery. However, under the physiological environment, Chol is rapidly extracted from the lipid bilayer by biomembranes, which jeopardizes membrane stability and results in premature leakage for delivered payloads, yielding suboptimal clinic efficacy. Herein, we report a Chol-modified sphingomyelin (SM) lipid bilayer via covalently conjugating Chol to SM (SM-Chol), which retains membrane condensing ability of Chol. Systemic structure activity relationship screening demonstrates that SM-Chol with a disulfide bond and longer linker outperforms other counterparts and conventional phospholipids/Chol mixture systems on blocking Chol transfer and payload leakage, increases maximum tolerated dose of vincristine while reducing systemic toxicities, improves pharmacokinetics and tumor delivery efficiency, and enhances antitumor efficacy in SU-DHL-4 diffuse large B-cell lymphoma xenograft model in female mice. Furthermore, SM-Chol improves therapeutic delivery of structurally diversified therapeutic agents (irinotecan, doxorubicin, dexamethasone) or siRNA targeting multi-drug resistant gene (p-glycoprotein) in late-stage metastatic orthotopic KPC-Luc pancreas cancer, 4T1-Luc2 triple negative breast cancer, lung inflammation, and CT26 colorectal cancer animal models in female mice compared to respective FDA-approved nanotherapeutics or lipid compositions. Thus, SM-Chol represents a promising platform for universal and improved drug delivery.
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Affiliation(s)
- Zhiren Wang
- Skaggs Pharmaceutical Sciences Center, Department of Pharmacology & Toxicology, R. Ken Coit College of Pharmacy, The University of Arizona, Tucson, AZ, 85721, USA
| | - Wenpan Li
- Skaggs Pharmaceutical Sciences Center, Department of Pharmacology & Toxicology, R. Ken Coit College of Pharmacy, The University of Arizona, Tucson, AZ, 85721, USA
| | - Yanhao Jiang
- Skaggs Pharmaceutical Sciences Center, Department of Pharmacology & Toxicology, R. Ken Coit College of Pharmacy, The University of Arizona, Tucson, AZ, 85721, USA
| | - Jonghan Park
- Skaggs Pharmaceutical Sciences Center, Department of Pharmacology & Toxicology, R. Ken Coit College of Pharmacy, The University of Arizona, Tucson, AZ, 85721, USA
| | - Karina Marie Gonzalez
- Skaggs Pharmaceutical Sciences Center, Department of Pharmacology & Toxicology, R. Ken Coit College of Pharmacy, The University of Arizona, Tucson, AZ, 85721, USA
| | - Xiangmeng Wu
- Skaggs Pharmaceutical Sciences Center, Department of Pharmacology & Toxicology, R. Ken Coit College of Pharmacy, The University of Arizona, Tucson, AZ, 85721, USA
| | - Qing-Yu Zhang
- Skaggs Pharmaceutical Sciences Center, Department of Pharmacology & Toxicology, R. Ken Coit College of Pharmacy, The University of Arizona, Tucson, AZ, 85721, USA
- Southwest Environmental Health Sciences Center, The University of Arizona, Tucson, 85721, USA
| | - Jianqin Lu
- Skaggs Pharmaceutical Sciences Center, Department of Pharmacology & Toxicology, R. Ken Coit College of Pharmacy, The University of Arizona, Tucson, AZ, 85721, USA.
- Southwest Environmental Health Sciences Center, The University of Arizona, Tucson, 85721, USA.
- Clinical and Translational Oncology Program (CTOP), The University of Arizona Cancer Center, Tucson, AZ, 85721, USA.
- BIO5 Institute, The University of Arizona, Tucson, AZ, 85721, USA.
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16
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Otrin N, Otrin L, Bednarz C, Träger TK, Hamdi F, Kastritis PL, Ivanov I, Sundmacher K. Protein-Rich Rafts in Hybrid Polymer/Lipid Giant Unilamellar Vesicles. Biomacromolecules 2024; 25:778-791. [PMID: 38190609 PMCID: PMC10865357 DOI: 10.1021/acs.biomac.3c00972] [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: 09/13/2023] [Revised: 12/20/2023] [Accepted: 12/20/2023] [Indexed: 01/10/2024]
Abstract
Considerable attention has been dedicated to lipid rafts due to their importance in numerous cell functions such as membrane trafficking, polarization, and signaling. Next to studies in living cells, artificial micrometer-sized vesicles with a minimal set of components are established as a major tool to understand the phase separation dynamics and their intimate interplay with membrane proteins. In parallel, mixtures of phospholipids and certain amphiphilic polymers simultaneously offer an interface for proteins and mimic this segregation behavior, presenting a tangible synthetic alternative for fundamental studies and bottom-up design of cellular mimics. However, the simultaneous insertion of complex and sensitive membrane proteins is experimentally challenging and thus far has been largely limited to natural lipids. Here, we present the co-reconstitution of the proton pump bo3 oxidase and the proton consumer ATP synthase in hybrid polymer/lipid giant unilamellar vesicles (GUVs) via fusion/electroformation. Variations of the current method allow for tailored reconstitution protocols and control of the vesicle size. In particular, mixing of protein-free and protein-functionalized nanosized vesicles in the electroformation film results in larger GUVs, while separate reconstitution of the respiratory enzymes enables higher ATP synthesis rates. Furthermore, protein labeling provides a synthetic mechanism for phase separation and protein sequestration, mimicking lipid- and protein-mediated domain formation in nature. The latter means opens further possibilities for re-enacting phenomena like supercomplex assembly or symmetry breaking and enriches the toolbox of bottom-up synthetic biology.
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Affiliation(s)
- Nika Otrin
- Process
Systems Engineering, Max Planck Institute
for Dynamics of Complex Technical Systems, Sandtorstrasse 1, 39106 Magdeburg, Germany
| | - Lado Otrin
- Process
Systems Engineering, Max Planck Institute
for Dynamics of Complex Technical Systems, Sandtorstrasse 1, 39106 Magdeburg, Germany
| | - Claudia Bednarz
- Process
Systems Engineering, Max Planck Institute
for Dynamics of Complex Technical Systems, Sandtorstrasse 1, 39106 Magdeburg, Germany
| | - Toni K. Träger
- Interdisciplinary
Research Center HALOmem and Institute of Biochemistry and Biotechnology, Martin Luther University Halle-Wittenberg, Biozentrum, 06120 Halle/Saale, Germany
| | - Farzad Hamdi
- Interdisciplinary
Research Center HALOmem and Institute of Biochemistry and Biotechnology, Martin Luther University Halle-Wittenberg, Biozentrum, 06120 Halle/Saale, Germany
| | - Panagiotis L. Kastritis
- Interdisciplinary
Research Center HALOmem and Institute of Biochemistry and Biotechnology, Martin Luther University Halle-Wittenberg, Biozentrum, 06120 Halle/Saale, Germany
- Institute
of Chemical Biology, National Hellenic Research
Foundation, 11635 Athens, Greece
| | - Ivan Ivanov
- Process
Systems Engineering, Max Planck Institute
for Dynamics of Complex Technical Systems, Sandtorstrasse 1, 39106 Magdeburg, Germany
- Grup
de Biotecnologia Molecular i Industrial, Department of Chemical Engineering, Universitat Politècnica de Catalunya, Rambla Sant Nebridi 22, 08222 Terrassa, Spain
| | - Kai Sundmacher
- Process
Systems Engineering, Max Planck Institute
for Dynamics of Complex Technical Systems, Sandtorstrasse 1, 39106 Magdeburg, Germany
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17
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Matsuki Y, Iwamoto M, Oiki S. Asymmetric Lipid Bilayers and Potassium Channels Embedded Therein in the Contact Bubble Bilayer. Methods Mol Biol 2024; 2796:1-21. [PMID: 38856892 DOI: 10.1007/978-1-0716-3818-7_1] [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] [Indexed: 06/11/2024]
Abstract
Cell membranes are highly intricate systems comprising numerous lipid species and membrane proteins, where channel proteins, lipid molecules, and lipid bilayers, as continuous elastic fabric, collectively engage in multi-modal interplays. Owing to the complexity of the native cell membrane, studying the elementary processes of channel-membrane interactions necessitates a bottom-up approach starting from forming simplified synthetic membranes. This is the rationale for establishing an in vitro membrane reconstitution system consisting of a lipid bilayer with a defined lipid composition and a channel molecule. Recent technological advancements have facilitated the development of asymmetric membranes, and the contact bubble bilayer (CBB) method allows single-channel current recordings under arbitrary lipid compositions in asymmetric bilayers. Here, we present an experimental protocol for the formation of asymmetric membranes using the CBB method. The KcsA potassium channel is a prototypical model channel with huge structural and functional information and thus serves as a reporter of membrane actions on the embedded channels. We demonstrate specific interactions of anionic lipids in the inner leaflet. Considering that the local lipid composition varies steadily in cell membranes, we `present a novel lipid perfusion technique that allows rapidly changing the lipid composition while monitoring the single-channel behavior. Finally, we demonstrate a leaflet perfusion method for modifying the composition of individual leaflets. These techniques with custom synthetic membranes allow for variable experiments, providing crucial insights into channel-membrane interplay in cell membranes.
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Affiliation(s)
- Yuka Matsuki
- Department of Anesthesiology and Reanimatology, Faculty of Medical Sciences, University of Fukui, Fukui, Japan
| | - Masayuki Iwamoto
- Department of Molecular Neuroscience, Faculty of Medical Sciences, University of Fukui, Fukui, Japan
| | - Shigetoshi Oiki
- Biomedical Imaging Research Center, University of Fukui, Fukui, Japan.
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18
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Żak A, Korshunova K, Rajtar N, Kulig W, Kepczynski M. Deciphering Lipid Arrangement in Phosphatidylserine/Phosphatidylcholine Mixed Membranes: Simulations and Experiments. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:18995-19007. [PMID: 38096496 PMCID: PMC10753890 DOI: 10.1021/acs.langmuir.3c03061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Revised: 11/24/2023] [Accepted: 11/26/2023] [Indexed: 12/27/2023]
Abstract
Phosphatidylserine (PS) exposure on the plasma membrane is crucial for many cellular processes including apoptotic cell recognition, blood clotting regulation, cellular signaling, and intercellular interactions. In this study, we investigated the arrangement of PS headgroups in mixed PS/phosphatidylcholine (PC) bilayers, serving as a simplified model of the outer leaflets of mammalian cell plasma membranes. Combining atomistic-scale molecular dynamics (MD) simulations with Langmuir monolayer experiments, we unraveled the mutual miscibility of POPC and POPS lipids and the intricate intermolecular interactions inherent to these membranes as well as the disparities in position and orientation of PC and PS headgroups. Our experiments revealed micrometer-scale miscibility at all mole fractions of POPC and POPS, marked by modest deviations from ideal mixing with no apparent microscale phase separation. The MD simulations, meanwhile, demonstrated that these deviations were due to strong electrostatic interactions between like-lipid pairs (POPC-POPC and POPS-POPS), culminating in lateral segregation and nanoscale clustering. Notably, PS headgroups profoundly affect the ordering of the lipid acyl chains, leading to lipid elongation and subtle PS protrusion above the zwitterionic membrane. In addition, PC headgroups are more tilted with respect to the membrane normal, while PS headgroups align at a smaller angle, making them more exposed to the surface of the mixed PC/PS membranes. These findings provide a detailed molecular-level account of the organization of mixed PC/PS membranes, corroborated by experimental data. The insights gained here extend our comprehension of the physiological role of PSs.
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Affiliation(s)
- Agata Żak
- Faculty
of Chemistry, Jagiellonian University, Gronostajowa 2, 30-387 Kraków, Poland
| | - Ksenia Korshunova
- Department
of Physics, University of Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
| | - Natan Rajtar
- Faculty
of Chemistry, Jagiellonian University, Gronostajowa 2, 30-387 Kraków, Poland
| | - Waldemar Kulig
- Department
of Physics, University of Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
| | - Mariusz Kepczynski
- Faculty
of Chemistry, Jagiellonian University, Gronostajowa 2, 30-387 Kraków, Poland
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19
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Chiu HY, Chang HT, Chan PC, Chiu PY. Cholesterol Levels, Hormone Replacement Therapy, and Incident Dementia among Older Adult Women. Nutrients 2023; 15:4481. [PMID: 37892556 PMCID: PMC10610485 DOI: 10.3390/nu15204481] [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: 09/15/2023] [Revised: 10/13/2023] [Accepted: 10/20/2023] [Indexed: 10/29/2023] Open
Abstract
Previous studies revealed that hormone replacement therapy (HRT) probably has a protective effect for preventing dementia in post-menopausal women. However, the results were still controversial. The association between cholesterol levels and incident dementia in older women is not fully understood either. We conducted a retrospective analysis on a cohort of non-demented women aged older than 50 years, which was registered in the History-based Artificial Intelligence Clinical Dementia Diagnostic System database from September 2015 to August 2021. We followed this cohort longitudinally to examine the rates of conversion to dementia. Using a Cox regression model, we investigated the impact of the quartile of total cholesterol (TC) levels on incident dementia, adjusting for age, sex, education, neuropsychiatric symptoms, neuropsychological assessments, HRT, as well as various vascular risk factors and medications. We examined a cohort of 787 participants, comprising 539 (68.5%) individuals who did not develop dementia (non-converters). Among these non-converters, 68 individuals (12.6%) were treated with HRT. By contrast, there were 248 (31.5%) who did develop dementia (converters). Among the converters, 28 individuals (11.3%) were treated with HRT. The average follow-up durations were 2.9 ± 1.5 and 3.3 ± 1.6 years for non-converters and converters, respectively. Compared to the lowest quartile of TC levels (<153), the hazard ratios (HR) for converting to dementia were 0.61, 0.58, and 0.58 for the second (153-176), third (177-201), and highest (>201) quartiles, respectively (all p < 0.05). However, the low-density lipoprotein cholesterol (LDL-C) level and HRT did not alter the rate of conversion to dementia. In conclusion, the lowest quartile of TC increased incident dementia in post-menopausal women without dementia; however, HRT did not contribute to conversion to dementia. Some studies suggest that post-menopausal women who have reduced estrogen levels might have an increased risk of Alzheimer's disease if they also have high cholesterol. Nonetheless, the evidence is inconclusive, as not all studies support this finding. The "Lower LDL-C is better" strategy for preventing cardiac vascular disease should be re-examined for the possible serial adverse effects of new onset dementia due to very low cholesterol levels.
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Affiliation(s)
- Huei-Ying Chiu
- Department of Obstetrics and Gynecology, Show Chwan Memorial Hospital, Changhua 500, Taiwan;
| | - Hsin-Te Chang
- Department of Psychology, College of Science, Chung Yuan Christian University, Taoyuan 320, Taiwan;
| | - Po-Chi Chan
- Department of Neurology, Show Chwan Memorial Hospital, Changhua 500, Taiwan;
| | - Pai-Yi Chiu
- Department of Neurology, Show Chwan Memorial Hospital, Changhua 500, Taiwan;
- Department of Applied Mathematics, Tunghai University, Taichung 407, Taiwan
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20
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Sarkar P, Chattopadhyay A. Interplay of Cholesterol and Actin in Neurotransmitter GPCR Signaling: Insights from Chronic Cholesterol Depletion Using Statin. ACS Chem Neurosci 2023; 14:3855-3868. [PMID: 37804226 DOI: 10.1021/acschemneuro.3c00472] [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] [Indexed: 10/09/2023] Open
Abstract
Serotonin1A receptors are important neurotransmitter receptors in the G protein-coupled receptor (GPCR) family and modulate a variety of neurological, behavioral, and cognitive functions. We recently showed that chronic cholesterol depletion by statins, potent inhibitors of HMG-CoA reductase (the rate-limiting enzyme in cholesterol biosynthesis), leads to polymerization of the actin cytoskeleton that alters lateral diffusion of serotonin1A receptors. However, cellular signaling by the serotonin1A receptor under chronic cholesterol depletion remains unexplored. In this work, we explored signaling by the serotonin1A receptor under statin-treated condition. We show that cAMP signaling by the receptor is reduced upon lovastatin treatment due to reduction in cholesterol as well as polymerization of the actin cytoskeleton. To the best of our knowledge, these results constitute the first report describing the effect of chronic cholesterol depletion on the signaling of a G protein-coupled neuronal receptor. An important message arising from these results is that it is prudent to include the contribution of actin polymerization while analyzing changes in membrane protein function due to chronic cholesterol depletion by statins. Notably, our results show that whereas actin polymerization acts as a negative regulator of cAMP signaling, cholesterol could act as a positive modulator. These results assume significance in view of reports highlighting symptoms of anxiety and depression in humans upon statin administration and the role of serotonin1A receptors in anxiety and depression. Overall, these results reveal a novel role of actin polymerization induced by chronic cholesterol depletion in modulating GPCR signaling, which could act as a potential therapeutic target.
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Affiliation(s)
- Parijat Sarkar
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India
| | - Amitabha Chattopadhyay
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India
- Academy of Scientific and Innovative Research, Ghaziabad 201 002, India
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21
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Aguilar J, Malacrida L, Gunther G, Torrado B, Torres V, Urbano BF, Sánchez SA. Cells immersed in collagen matrices show a decrease in plasma membrane fluidity as the matrix stiffness increases. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2023; 1865:184176. [PMID: 37328024 DOI: 10.1016/j.bbamem.2023.184176] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Revised: 05/10/2023] [Accepted: 05/15/2023] [Indexed: 06/18/2023]
Abstract
Cells are constantly adapting to maintain their identity in response to the surrounding media's temporal and spatial heterogeneity. The plasma membrane, which participates in the transduction of external signals, plays a crucial role in this adaptation. Studies suggest that nano and micrometer areas with different fluidities at the plasma membrane change their distribution in response to external mechanical signals. However, investigations linking fluidity domains with mechanical stimuli, specifically matrix stiffness, are still in progress. This report tests the hypothesis that the stiffness of the extracellular matrix can modify the equilibrium of areas with different order in the plasma membrane, resulting in changes in overall membrane fluidity distribution. We studied the effect of matrix stiffness on the distribution of membrane lipid domains in NIH-3 T3 cells immersed in matrices of varying concentrations of collagen type I, for 24 or 72 h. The stiffness and viscoelastic properties of the collagen matrices were characterized by rheometry, fiber sizes were measured by Scanning Electron Microscopy (SEM) and the volume occupied by the fibers by second harmonic generation imaging (SHG). Membrane fluidity was measured using the fluorescent dye LAURDAN and spectral phasor analysis. The results demonstrate that an increase in collagen stiffness alters the distribution of membrane fluidity, leading to an increasing amount of the LAURDAN fraction with a high degree of packing. These findings suggest that changes in the equilibrium of fluidity domains could represent a versatile and refined component of the signal transduction mechanism for cells to respond to the highly heterogeneous matrix structural composition. Overall, this study sheds light on the importance of the plasma membrane's role in adapting to the extracellular matrix's mechanical cues.
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Affiliation(s)
- Joao Aguilar
- Laboratorio de Interacciones Macromoleculares (LIMM), Departamento de Polímeros, Facultad de Ciencias Químicas, Universidad de Concepción, Concepción, Chile
| | - Leonel Malacrida
- Departamento de Fisiopatología, Hospital de Clínicas, Universidad de la República, Montevideo, Uruguay; Advanced Bioimaging Unit, Institut Pasteur Montevideo, Universidad de la República, Montevideo, Uruguay
| | - German Gunther
- Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile
| | - Belén Torrado
- Biomedical Engineering Department, University of California at Irvine, California, USA
| | - Viviana Torres
- Departamento de Bioquímica, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile
| | - Bruno F Urbano
- Laboratorio de Interacciones Macromoleculares (LIMM), Departamento de Polímeros, Facultad de Ciencias Químicas, Universidad de Concepción, Concepción, Chile
| | - Susana A Sánchez
- Laboratorio de Interacciones Macromoleculares (LIMM), Departamento de Polímeros, Facultad de Ciencias Químicas, Universidad de Concepción, Concepción, Chile.
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22
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Flak D, Zalewski T, Fiedorowicz K, Przysiecka Ł, Jarek M, Klimaszyk A, Kempka M, Zimna A, Rozwadowska N, Avaro J, Liebi M, Nowaczyk G. Hybrids of manganese oxide and lipid liquid crystalline nanoparticles (LLCNPs@MnO) as potential magnetic resonance imaging (MRI) contrast agents. J Mater Chem B 2023; 11:8732-8753. [PMID: 37655519 DOI: 10.1039/d3tb01110k] [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: 09/02/2023]
Abstract
Due to the health risks associated with the use of Gd-chelates and the promising effects of using nanoparticles as T1 contrast agents (CAs) for MRI, Mn-based nanoparticles are considered a highly competitive alternative. The use of hybrid constructs with paramagnetic functionality of Mn-based nanoparticles is an effective approach, in particular, the use of biocompatible lipid liquid crystalline nanoparticles (LLCNPs) as a carrier of MnO nanoparticles. LLCNPs possess a unique internal structure ensuring a payload of different polarity MnO nanoparticles. In view of MRI application, the surface properties including the polarity of MnO are crucial factors determining their relaxation rate and thus the MRI efficiency. Two novel hybrid constructs consisting of LLCNPs loaded with hydrophobic MnO-oleate and hydrophilic MnO-DMSA NPs were prepared. These nanosystems were studied in terms of their physico-chemical properties, positive T1 contrast enhancement properties (in vitro and in vivo) and biological safety. LLCNPs@MnO-oleate and LLCNPs@MnO-DMSA hybrids exhibited a heterogeneous phase composition, however with differences in the inner periodic arrangement and structural parameters, as well as in the preferable localization of MnO NPs within the LLCNPs. Also, these hybrids differed in terms of particle size-related parameters and colloidal stability, which was found to be strongly dependent on the addition of differently functionalized MnO NPs. Embedding both types of MnO NPs into LLCNPs resulted in high relaxivity parameters, in comparison to bare MnO-DMSA NPs and also commercially developed CAs (e.g. Dotarem and Teslascan). Further biosafety studies revealed that cell internalization pathways were dependent on the prepared hybrid type, while viability, effects on the mitochondria membrane potential and cytoskeletal networks were rather related to the susceptibility of the particular cell line. The high relaxation rates achieved with the developed hybrid LLCNPs@MnO enable them to be possibly used as novel and biologically safe MRI T1-enhancing CAs in in vivo imaging.
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Affiliation(s)
- Dorota Flak
- NanoBioMedical Centre, Adam Mickiewicz University Poznań, Wszechnicy Piastowskiej 3, 61-614 Poznań, Poland.
| | - Tomasz Zalewski
- NanoBioMedical Centre, Adam Mickiewicz University Poznań, Wszechnicy Piastowskiej 3, 61-614 Poznań, Poland.
| | - Katarzyna Fiedorowicz
- NanoBioMedical Centre, Adam Mickiewicz University Poznań, Wszechnicy Piastowskiej 3, 61-614 Poznań, Poland.
| | - Łucja Przysiecka
- NanoBioMedical Centre, Adam Mickiewicz University Poznań, Wszechnicy Piastowskiej 3, 61-614 Poznań, Poland.
| | - Marcin Jarek
- NanoBioMedical Centre, Adam Mickiewicz University Poznań, Wszechnicy Piastowskiej 3, 61-614 Poznań, Poland.
| | - Adam Klimaszyk
- NanoBioMedical Centre, Adam Mickiewicz University Poznań, Wszechnicy Piastowskiej 3, 61-614 Poznań, Poland.
| | - Marek Kempka
- NanoBioMedical Centre, Adam Mickiewicz University Poznań, Wszechnicy Piastowskiej 3, 61-614 Poznań, Poland.
- Department of Biomedical Physics, Faculty of Physics, Adam Mickiewicz University Poznań, Uniwersytetu Poznańskiego 2, 61-614 Poznań, Poland
| | - Agnieszka Zimna
- Institute of Human Genetics Polish Academy of Sciences, Strzeszyńska 32, 60-479 Poznań, Poland
| | - Natalia Rozwadowska
- Institute of Human Genetics Polish Academy of Sciences, Strzeszyńska 32, 60-479 Poznań, Poland
| | - Jonathan Avaro
- Empa - Swiss Federal Laboratories for Materials Science and Technology, Center for X-ray Analytics and Biomimetic Membranes and Textiles, Lerchenfeldstrasse 5, 9014 St. Gallen, Switzerland
| | - Marianne Liebi
- Empa - Swiss Federal Laboratories for Materials Science and Technology, Center for X-ray Analytics, Lerchenfeldstrasse 5, 9014 St. Gallen, Switzerland
| | - Grzegorz Nowaczyk
- NanoBioMedical Centre, Adam Mickiewicz University Poznań, Wszechnicy Piastowskiej 3, 61-614 Poznań, Poland.
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23
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Heller WT. Small-Angle Neutron Scattering Study of a Phosphatidylcholine-Phosphatidylethanolamine Mixture. ACS OMEGA 2023; 8:33755-33762. [PMID: 37744859 PMCID: PMC10515593 DOI: 10.1021/acsomega.3c04164] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Accepted: 08/23/2023] [Indexed: 09/26/2023]
Abstract
The properties of single-component phospholipid lipid bilayers have been extensively characterized. Natural cell membranes are not so simple, consisting of a diverse mixture of lipids and proteins. While having detailed structural information on complex membranes would be useful for understanding their structure and function, experimentally characterizing such membranes at a level of detail applied to model phospholipid bilayers is challenging. Here, small-angle neutron scattering with selective deuteration was used to characterize a binary lipid mixture composed of 1,2-dimyristoyl-3-sn-glycero-phosphatidylcholine and 1,2-dimyristoyl-3-sn-glycero-phosphatidylethanolamine. The data analysis provided the area per lipid in each leaflet as well as the asymmetry of the composition of the inner and outer leaflets of the bilayer. The results provide new insight into the structure of the lipid bilayer when this lipid mixture is used to prepare vesicles.
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Affiliation(s)
- William T. Heller
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
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24
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Hahn KM, Itano MS, Loew LM, Vitriol EA. Celebrating the creative scientific life of Ken Jacobson. Biophys J 2023; 122:E1-E4. [PMID: 37643609 PMCID: PMC10541490 DOI: 10.1016/j.bpj.2023.08.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2023] [Revised: 08/15/2023] [Accepted: 08/15/2023] [Indexed: 08/31/2023] Open
Affiliation(s)
- Klaus M Hahn
- Department of Pharmacology, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Michelle S Itano
- Department of Cell Biology & Physiology, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Leslie M Loew
- Richard D. Berlin Center for Cell Analysis and Modeling, University of Connecticut School of Medicine, Farmington, Connecticut
| | - Eric A Vitriol
- Department of Neuroscience & Regenerative Medicine, Medical College of Georgia at Augusta University, Augusta, Georgia.
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25
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Lin X, Lin K, He S, Zhou Y, Li X, Lin X. Membrane Domain Anti-Registration Induces an Intrinsic Transmembrane Potential. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:11621-11627. [PMID: 37563986 DOI: 10.1021/acs.langmuir.3c01137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/12/2023]
Abstract
Plasma membrane segregation into various nanoscale membrane domains is driven by distinct interactions between diverse lipids and proteins. Among them, liquid-ordered (Lo) membrane domains are defined as "lipid rafts" and liquid-disordered (Ld) ones as "lipid non-rafts". Using model membrane systems, both intra-leaflet and inter-leaflet dynamics of these membrane domains are widely studied. Nevertheless, the biological impact of the latter, which is accompanied by membrane domain registration/anti-registration, is far from clear. Hence, in this work, we studied the biological relevance of the membrane domain anti-registration using both all-atom molecular dynamics (MD) simulations and confocal fluorescence microscopy. All-atom MD simulations suggested an intrinsic transmembrane potential for the case of the membrane anti-registration (Lo/Ld). Meanwhile, confocal fluorescence microscopy experiments of HeLa and 293T cell lines indicated that membrane cholesterol depletion could significantly alter the transmembrane potential of cells. Considering differences in the cholesterol content between Lo and Ld membrane domains, our confocal fluorescence microscopy experiments are consistent with our all-atom MD simulations. In short, membrane domain anti-registration induces local membrane asymmetry and, thus, an intrinsic transmembrane potential.
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Affiliation(s)
- Xiaoqian Lin
- Beijing Advanced Innovation Center for Biomedical Engineering, School of Engineering Medicine & School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, China
- Shen Yuan Honors College, Beihang University, Beijing 100191, China
| | - Kaidong Lin
- Beijing Advanced Innovation Center for Biomedical Engineering, School of Engineering Medicine & School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, China
| | - Shiqi He
- Beijing Advanced Innovation Center for Biomedical Engineering, School of Engineering Medicine & School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, China
| | - Yue Zhou
- Beijing Advanced Innovation Center for Biomedical Engineering, School of Engineering Medicine & School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, China
| | - Xiu Li
- Beijing Advanced Innovation Center for Biomedical Engineering, School of Engineering Medicine & School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, China
| | - Xubo Lin
- Beijing Advanced Innovation Center for Biomedical Engineering, School of Engineering Medicine & School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, China
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26
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Camdzic M, Aga DS, Atilla-Gokcumen GE. Cellular Lipidome Changes during Retinoic Acid (RA)-Induced Differentiation in SH-SY5Y Cells: A Comprehensive In Vitro Model for Assessing Neurotoxicity of Contaminants. ENVIRONMENT & HEALTH (WASHINGTON, D.C.) 2023; 1:110-120. [PMID: 37614295 PMCID: PMC10443778 DOI: 10.1021/envhealth.3c00022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Revised: 05/25/2023] [Accepted: 05/26/2023] [Indexed: 08/25/2023]
Abstract
The SH-SY5Y, neuroblastoma cell line, is a common in vitro model used to study physiological neuronal function and the neuronal response to different stimuli, including exposure to toxic chemicals. These cells can be differentiated to neuron-like cells by administration of various reagents, including retinoic acid or phorbol-12-myristate-13-acetate. Despite their common use, there is an incomplete understanding of the molecular changes that occur during differentiation. Therefore, there is a critical need to fully understand the molecular changes that occur during differentiation to properly study neurotoxicity in response to various environmental exposures. Previous studies have investigated the proteome and transcriptome during differentiation; however, the regulation of the cellular lipidome in this process is unexplored. In this work, we conducted liquid chromatography-mass spectrometry (LC-MS)-based untargeted lipidomics in undifferentiated and differentiated SH-SY5Y cells, induced by retinoic acid. We show that there are global differences between the cellular lipidomes of undifferentiated and differentiated cells. Out of thousands of features detected in positive and negative electrospray ionization modes, 44 species were identified that showed significant differences (p-value ≤0.05, fold change ≥2) in differentiated cells. Identification of these features combined with targeted lipidomics highlighted the accumulation of phospholipids, sterols, and sphingolipids during differentiation while triacylglycerols were depleted. These results provide important insights into lipid-related changes that occur during cellular differentiation of SH-5YSY cells and emphasize the need for the detailed characterization of biochemical differences that occur during differentiation while using this in vitro model for assessing ecological impacts of environmental pollutants.
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Affiliation(s)
- Michelle Camdzic
- Department of Chemistry, University at Buffalo, The State University of New
York (SUNY), Buffalo, New York 14260, United States
| | - Diana S. Aga
- Department of Chemistry, University at Buffalo, The State University of New
York (SUNY), Buffalo, New York 14260, United States
| | - G. Ekin Atilla-Gokcumen
- Department of Chemistry, University at Buffalo, The State University of New
York (SUNY), Buffalo, New York 14260, United States
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27
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Ledesma-Durán A, Juárez-Valencia LH. Diffusion coefficients and MSD measurements on curved membranes and porous media. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2023; 46:70. [PMID: 37578670 DOI: 10.1140/epje/s10189-023-00329-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Accepted: 07/28/2023] [Indexed: 08/15/2023]
Abstract
We study some geometric aspects that influence the transport properties of particles that diffuse on curved surfaces. We compare different approaches to surface diffusion based on the Laplace-Beltrami operator adapted to predict concentration along entire membranes, confined subdomains along surfaces, or within porous media. Our goal is to summarize, firstly, how diffusion in these systems results in different types of diffusion coefficients and mean square displacement measurements, and secondly, how these two factors are affected by the concavity of the surface, the shape of the possible barriers or obstacles that form the available domains, the sinuosity, tortuosity, and constrictions of the trajectories and even how the observation plane affects the measurements of the diffusion. In addition to presenting a critical and organized comparison between different notions of MSD, in this review, we test the correspondence between theoretical predictions and numerical simulations by performing finite element simulations and illustrate some situations where diffusion theory can be applied. We briefly reviewed computational schemes for understanding surface diffusion and finally, discussed how this work contributes to understanding the role of surface diffusion transport properties in porous media and their relationship to other transport processes.
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Affiliation(s)
- Aldo Ledesma-Durán
- Departmento de Matemáticas, Universidad Autónoma Metropolitana, CDMX, Mexico
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28
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Almadhi S, Forth J, Rodriguez-Arco L, Duro-Castano A, Williams I, Ruiz-Pérez L, Battaglia G. Bottom-Up Preparation of Phase-Separated Polymersomes. Macromol Biosci 2023; 23:e2300068. [PMID: 37315231 DOI: 10.1002/mabi.202300068] [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: 02/20/2023] [Revised: 05/20/2023] [Indexed: 06/16/2023]
Abstract
A bottom-up approach to fabricating monodisperse, two-component polymersomes that possess phase-separated ("patchy") chemical topology is presented. This approach is compared with already-existing top-down preparation methods for patchy polymer vesicles, such as film rehydration. These findings demonstrate a bottom-up, solvent-switch self-assembly approach that produces a high yield of nanoparticles of the target size, morphology, and surface topology for drug delivery applications, in this case patchy polymersomes of a diameter of ≈50 nm. In addition, an image processing algorithm to automatically calculate polymersome size distributions from transmission electron microscope images based on a series of pre-processing steps, image segmentation, and round object identification is presented.
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Affiliation(s)
- Safa Almadhi
- Department of Chemistry, University College London, London, WC1H 0AJ, UK
| | - Joe Forth
- Department of Chemistry, University College London, London, WC1H 0AJ, UK
| | - Laura Rodriguez-Arco
- Department of Chemistry, University College London, London, WC1H 0AJ, UK
- Department of Applied Physics, Faculty of Sciences, University of Granada, Granada, 18071, Spain
| | - Aroa Duro-Castano
- Department of Chemistry, University College London, London, WC1H 0AJ, UK
- Curapath, Valencia, 46980, Spain
| | - Ian Williams
- Department of Chemistry, University College London, London, WC1H 0AJ, UK
- Department of Physics, University of Surrey, Guildford, GU2 7XH, UK
- Institute for Bioengineering of Catalonia, The Barcelona Institute of Science and Technology, Barcelona, 08028, Spain
| | - Lorena Ruiz-Pérez
- Department of Chemistry, University College London, London, WC1H 0AJ, UK
- Institute for Bioengineering of Catalonia, The Barcelona Institute of Science and Technology, Barcelona, 08028, Spain
| | - Giuseppe Battaglia
- Department of Chemistry, University College London, London, WC1H 0AJ, UK
- Institute for Bioengineering of Catalonia, The Barcelona Institute of Science and Technology, Barcelona, 08028, Spain
- Catalan Institution of Research and Advanced Studies, Barcelona, 08010, Spain
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29
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Puff N. Critical Role of Molecular Packing in Lo Phase Membrane Solubilization. MEMBRANES 2023; 13:652. [PMID: 37505018 PMCID: PMC10385406 DOI: 10.3390/membranes13070652] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Revised: 06/30/2023] [Accepted: 07/04/2023] [Indexed: 07/29/2023]
Abstract
Membrane solubilization induced by Triton X-100 (TX-100) was investigated. Different membrane compositions and phase states were studied along the detergent titration. Expected solubilization profiles were obtained but new information is provided. The fluorescence of nitrobenzoxadiazole (NBD)-labeled lipids indicates that the liquid-ordered (Lo)/liquid-disordered (Ld) phase coexistence is barely unaffected at sub-solubilizing detergent concentrations and highlights the vesicle-to-micelle transition. Moreover, the location of the NBD group in the bilayer emphasizes a detergent-membrane interaction in the case of the insoluble Lo phase membrane. It has also been shown that the molecular packing of the membrane loosens in the presence of TX-100, regardless of the solubilization profile. Motivated by studies on GPMVs, the solubilization of less ordered Lo phase membranes was considered in order to improve the effect of molecular packing on the extent of solubilization. Membranes composed of SM and Chol in an equimolar ratio doped with different amounts of PC were studied. The more ordered the Lo phase membrane is in the absence of detergent, the less likely it is to be solubilized. Furthermore, and in contrast to what is observed for membranes exhibiting an Lo/Ld phase coexistence, a very small decrease in the molecular packing of the Lo phase membrane radically modifies the extent of solubilization. These results have implications for the reliability of TX-100 insolubility as a method to detect ordered domains.
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Affiliation(s)
- Nicolas Puff
- Faculté des Sciences et Ingénierie, Sorbonne Université, UFR 925 Physics, F-75005 Paris, France
- Laboratoire Matière et Systèmes Complexes (MSC), UMR 7057 CNRS, Université Paris Cité, F-75013 Paris, France
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30
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Saini P, Anugula S, Fong YW. The Role of ATP-Binding Cassette Proteins in Stem Cell Pluripotency. Biomedicines 2023; 11:1868. [PMID: 37509507 PMCID: PMC10377311 DOI: 10.3390/biomedicines11071868] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Revised: 06/20/2023] [Accepted: 06/22/2023] [Indexed: 07/30/2023] Open
Abstract
Pluripotent stem cells (PSCs) are highly proliferative cells that can self-renew indefinitely in vitro. Upon receiving appropriate signals, PSCs undergo differentiation and can generate every cell type in the body. These unique properties of PSCs require specific gene expression patterns that define stem cell identity and dynamic regulation of intracellular metabolism to support cell growth and cell fate transitions. PSCs are prone to DNA damage due to elevated replicative and transcriptional stress. Therefore, mechanisms to prevent deleterious mutations in PSCs that compromise stem cell function or increase the risk of tumor formation from becoming amplified and propagated to progenitor cells are essential for embryonic development and for using PSCs including induced PSCs (iPSCs) as a cell source for regenerative medicine. In this review, we discuss the role of the ATP-binding cassette (ABC) superfamily in maintaining PSC homeostasis, and propose how their activities can influence cellular signaling and stem cell fate decisions. Finally, we highlight recent discoveries that not all ABC family members perform only canonical metabolite and peptide transport functions in PSCs; rather, they can participate in diverse cellular processes from genome surveillance to gene transcription and mRNA translation, which are likely to maintain the pristine state of PSCs.
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Affiliation(s)
- Prince Saini
- Brigham Regenerative Medicine Center, Brigham and Women’s Hospital, Boston, MA 02115, USA; (P.S.); (S.A.)
- Department of Medicine, Cardiovascular Medicine Division, Harvard Medical School, Boston, MA 02115, USA
- Harvard Stem Cell Institute, Cambridge, MA 02138, USA
| | - Sharath Anugula
- Brigham Regenerative Medicine Center, Brigham and Women’s Hospital, Boston, MA 02115, USA; (P.S.); (S.A.)
- Department of Medicine, Cardiovascular Medicine Division, Harvard Medical School, Boston, MA 02115, USA
- Harvard Stem Cell Institute, Cambridge, MA 02138, USA
| | - Yick W. Fong
- Brigham Regenerative Medicine Center, Brigham and Women’s Hospital, Boston, MA 02115, USA; (P.S.); (S.A.)
- Department of Medicine, Cardiovascular Medicine Division, Harvard Medical School, Boston, MA 02115, USA
- Harvard Stem Cell Institute, Cambridge, MA 02138, USA
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31
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Ladbury JE, Lin CC, Suen KM. Phase separation enhances probability of receptor signalling and drug targeting. Trends Biochem Sci 2023; 48:428-436. [PMID: 36759237 DOI: 10.1016/j.tibs.2023.01.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Revised: 01/10/2023] [Accepted: 01/17/2023] [Indexed: 02/10/2023]
Abstract
The probability of a given receptor tyrosine kinase (RTK) triggering a defined cellular outcome is low because of the promiscuous nature of signalling, the randomness of molecular diffusion through the cell, and the ongoing nonfunctional submembrane signalling activity or noise. Signal transduction is therefore a 'numbers game', where enough cell surface receptors and effector proteins must initially be engaged to guarantee formation of a functional signalling complex against a background of redundant events. The presence of intracellular liquid-liquid phase separation (LLPS) at the plasma membrane provides a mechanism through which the probabilistic nature of signalling can be weighted in favour of the required, discrete cellular outcome and mutual exclusivity in signal initiation.
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Affiliation(s)
- John E Ladbury
- School of Molecular and Cellular Biology, University of Leeds, Leeds, LS2 9JT, UK.
| | - Chi-Chuan Lin
- School of Molecular and Cellular Biology, University of Leeds, Leeds, LS2 9JT, UK
| | - Kin Man Suen
- School of Molecular and Cellular Biology, University of Leeds, Leeds, LS2 9JT, UK
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32
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Malik S, Karmakar S, Debnath A. Quantifying dynamical heterogeneity length scales of interface water across model membrane phase transitions. J Chem Phys 2023; 158:091103. [PMID: 36889951 DOI: 10.1063/5.0137727] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023] Open
Abstract
All-atom molecular dynamics simulations of 1,2-dimyristoyl-sn-glycero-3-phosphocholine lipid membranes reveal a drastic growth in the heterogeneity length scales of interface water (IW) across fluid to ripple to gel phase transitions. It acts as an alternate probe to capture the ripple size of the membrane and follows an activated dynamical scaling with the relaxation time scale solely within the gel phase. The results quantify the mostly unknown correlations between the spatiotemporal scales of the IW and membranes at various phases under physiological and supercooled conditions.
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Affiliation(s)
- Sheeba Malik
- Department of Chemistry, IIT Jodhpur, Jodhpur, Rajasthan, India
| | - Smarajit Karmakar
- Centre for Interdisciplinary Sciences, Tata Institute of Fundamental Research, Hyderabad, India
| | - Ananya Debnath
- Department of Chemistry, IIT Jodhpur, Jodhpur, Rajasthan, India
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33
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Ullo MF, Case LB. How cells sense and integrate information from different sources. WIREs Mech Dis 2023:e1604. [PMID: 36781396 DOI: 10.1002/wsbm.1604] [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: 06/24/2022] [Revised: 01/06/2023] [Accepted: 01/24/2023] [Indexed: 02/15/2023]
Abstract
Cell signaling is a fundamental cellular process that enables cells to sense and respond to information in their surroundings. At the molecular level, signaling is primarily carried out by transmembrane protein receptors that can initiate complex downstream signal transduction cascades to alter cellular behavior. In the human body, different cells can be exposed to a wide variety of environmental conditions, and cells express diverse classes of receptors capable of sensing and integrating different signals. Furthermore, different receptors and signaling pathways can crosstalk with each other to calibrate the cellular response. Crosstalk occurs through multiple mechanisms at different levels of signaling pathways. In this review, we discuss how cells sense and integrate different chemical, mechanical, and spatial signals as well as the mechanisms of crosstalk between pathways. To illustrate these concepts, we use a few well-studied signaling pathways, including receptor tyrosine kinases and integrin receptors. Finally, we discuss the implications of dysregulated cellular sensing on driving diseases such as cancer. This article is categorized under: Cancer > Molecular and Cellular Physiology Metabolic Diseases > Molecular and Cellular Physiology.
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Affiliation(s)
- Maria F Ullo
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Lindsay B Case
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
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34
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Reorganization of the outer layer of a model of the plasma membrane induced by a neuroprotective aminosterol. Colloids Surf B Biointerfaces 2023; 222:113115. [PMID: 36603410 DOI: 10.1016/j.colsurfb.2022.113115] [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: 10/10/2022] [Revised: 12/07/2022] [Accepted: 12/20/2022] [Indexed: 12/24/2022]
Abstract
Trodusquemine is an amphipathic aminosterol that has recently shown therapeutic benefit in neurodegenerative diseases altering the binding of misfolded proteins to the cell membrane. To unravel the underlying mechanism, we studied the interactions between Trodusquemine (TRO) and lipid monolayers simulating the outer layer of the plasma membrane. We selected two different compositions of dioleoylphosphatidylcholine (DOPC), sphingomyelin (SM), cholesterol (Chol) and monosialotetrahexosylganglioside (GM1) lipid mixture mimicking either a lipid-raft containing membrane (Ld+So phases) or a single-phase disordered membrane (Ld phase). Surface pressure-area isotherms and surface compressional modulus-area combined with Brewster Angle Microscopy (BAM) provided the thermodynamic and morphological information on the lipid monolayer in the presence of increasing amounts of TRO in the monolayer. Experiments revealed that TRO forms stable spreading monolayers at the buffer-air interface where it undergoes multiple reversible phase transitions to bi- and tri-layers at the interface. When TRO was spread at the interface with the lipid mixtures, we found that it distributes in the lipid monolayer for both the selected lipid compositions, but a maximum TRO uptake in the rafts-containing monolayer was observed for a Lipid/TRO molar ratio equal to 3:2. Statistical analysis of BAM images revealed that TRO induces a decrease in the size of the condensed domains, an increase in their number and in the thickness mismatch between the Ld and So phase. Experiments and MD simulations converge to indicate that TRO adsorbs preferentially at the border of the So domains. Removal of GM1 from the lipid Ld+So mixture resulted in an even greater TRO-mediated reduction of the size of the So domains suggesting that the presence of GM1 hinders the localization of TRO at the So domains boundaries. Taken together these observations suggest that Trodusquemine influences the organization of lipid rafts within the neuronal membrane in a dose-dependent manner whereas it evenly distributes in disordered expanded phases of the membrane model.
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35
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Hirano K, Kinoshita M, Matsumori N. Impact of sphingomyelin acyl chain heterogeneity upon properties of raft-like membranes. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2022; 1864:184036. [PMID: 36055359 DOI: 10.1016/j.bbamem.2022.184036] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Revised: 07/26/2022] [Accepted: 08/15/2022] [Indexed: 06/15/2023]
Abstract
Sphingomyelin (SM) is a main component of lipid rafts and characteristic of abundance of long and saturated acyl chains. Recently, we reported that fluorescence-labeled lipids including C16:0 and C18:0SMs retained membrane behaviors of inherent lipids. Here, we newly prepared fluorescent SMs with longer acyl chains, C22:0 and C24:1, for observing their partition and diffusion in SM/cholesterol (chol)/dioleoylphosphatidylcholine (DOPC) bilayers. Although fluorescent C24:1SM underwent a uniform distribution between ordered (Lo) and disordered (Ld) phases, other fluorescent SMs with saturated acyl chains were preferentially distributed in the Lo phase. Interestingly, when the acyl chains of fluorescent and membrane SMs are different, distribution of fluorescent SM to the Lo phase was reduced compared to when the acyl chains are the same. This tendency was also observed for C16:0SM/C22:0SM/chol/DOPC quaternary bilayers, where the minor SM was more excluded out of the Lo phase than the major SM. We also found that the coexistence of SMs induces SM efflux out of the Lo phase and simultaneous DOPC influx to the Lo phase, consequently reducing the difference in fluidity between the two phases. These results suggest that physicochemical properties of lipid rafts are regulated by the acyl chain heterogeneity of SMs.
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Affiliation(s)
- Kana Hirano
- Department of Chemistry, Graduate School of Science, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Masanao Kinoshita
- Department of Chemistry, Graduate School of Science, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan.
| | - Nobuaki Matsumori
- Department of Chemistry, Graduate School of Science, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan.
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36
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Modulation of gastric lipase adsorption onto mixed galactolipid-phospholipid films by addition of phytosterols. Colloids Surf B Biointerfaces 2022; 220:112933. [DOI: 10.1016/j.colsurfb.2022.112933] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Revised: 09/20/2022] [Accepted: 10/13/2022] [Indexed: 11/27/2022]
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37
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Heller WT. Small-Angle Neutron Scattering for Studying Lipid Bilayer Membranes. Biomolecules 2022; 12:1591. [PMID: 36358941 PMCID: PMC9687511 DOI: 10.3390/biom12111591] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Revised: 10/18/2022] [Accepted: 10/26/2022] [Indexed: 09/23/2023] Open
Abstract
Small-angle neutron scattering (SANS) is a powerful tool for studying biological membranes and model lipid bilayer membranes. The length scales probed by SANS, being from 1 nm to over 100 nm, are well-matched to the relevant length scales of the bilayer, particularly when it is in the form of a vesicle. However, it is the ability of SANS to differentiate between isotopes of hydrogen as well as the availability of deuterium labeled lipids that truly enable SANS to reveal details of membranes that are not accessible with the use of other techniques, such as small-angle X-ray scattering. In this work, an overview of the use of SANS for studying unilamellar lipid bilayer vesicles is presented. The technique is briefly presented, and the power of selective deuteration and contrast variation methods is discussed. Approaches to modeling SANS data from unilamellar lipid bilayer vesicles are presented. Finally, recent examples are discussed. While the emphasis is on studies of unilamellar vesicles, examples of the use of SANS to study intact cells are also presented.
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Affiliation(s)
- William T Heller
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
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38
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Liu Y, Zheng X, Guan D, Jiang X, Hu G. Heterogeneous Nanostructures Cause Anomalous Diffusion in Lipid Monolayers. ACS NANO 2022; 16:16054-16066. [PMID: 36149751 DOI: 10.1021/acsnano.2c04089] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
The diffusion and mobility in biomembranes are crucial for various cell functions; however, the mechanisms involved in such processes remain ambiguous due to the complex membrane structures. Herein, we investigate how the heterogeneous nanostructures cause anomalous diffusion in dipalmitoylphosphatidylcholine (DPPC) monolayers. By identifying the existence of condensed nanodomains and clarifying their impact, our findings renew the understanding of the hydrodynamic description and the statistical feature of the diffusion in the monolayers. We find a universal characteristic of the multistage mean square displacement (MSD) with an intermediate crossover, signifying two membrane viscosities at different scales: the short-time scale describes the local fluidity and is independent of the nominal DPPC density, and the long-time scale represents the global continuous phase taking into account nanodomains and increases with DPPC density. The constant short-time viscosity reflects a dynamic equilibrium between the continuous fluid phase and the condensed nanodomains in the molecular scale. Notably, we observe an "anomalous yet Brownian" phenomenon exhibiting an unusual double-peaked displacement probability distribution (DPD), which is attributed to the net dipolar repulsive force from the heterogeneous nanodomains around the microdomains. The findings provide physical insights into the transport of membrane inclusions that underpin various biological functions and drug deliveries.
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Affiliation(s)
- Yang Liu
- State Key Laboratory of Nonlinear Mechanics (LNM), Beijing Key Laboratory of Engineered Construction and Mechanobiology, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- Frontier Scientific Research Centre for Fluidized Mining of Deep Underground Resources, China University of Mining & Technology, Xuzhou 221116, People's Republic of China
| | - Xu Zheng
- State Key Laboratory of Nonlinear Mechanics (LNM), Beijing Key Laboratory of Engineered Construction and Mechanobiology, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - Dongshi Guan
- State Key Laboratory of Nonlinear Mechanics (LNM), Beijing Key Laboratory of Engineered Construction and Mechanobiology, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - Xikai Jiang
- State Key Laboratory of Nonlinear Mechanics (LNM), Beijing Key Laboratory of Engineered Construction and Mechanobiology, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - Guoqing Hu
- Department of Engineering Mechanics, State Key Laboratory of Fluid Power and Mechatronic Systems, Zhejiang University, Hangzhou 310027, People's Republic of China
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39
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Cavalcanti RRM, Lira RB, Riske KA. Membrane Fusion Biophysical Analysis of Fusogenic Liposomes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:10430-10441. [PMID: 35977420 DOI: 10.1021/acs.langmuir.2c01169] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Liposomes represent important drug carrier vehicles in biological systems. A fusogenic liposomal system composed of equimolar mixtures of the cationic lipid DOTAP and the phospholipid DOPE showed high fusion and delivery efficiencies with cells and lipid vesicles. However, aspects of the thermodynamics involving the interaction of these fusogenic liposomes and biomimetic systems remain unclear. Here, we investigate the fusion of this system with large unilamellar vesicles (LUVs) composed of the zwitterionic lipid POPC and increasing fractions of the anionic lipid POPG and up to 30 mol % cholesterol. The focus here is to concomitantly follow changes in size, zeta-potential, and enthalpy binding upon membrane interaction and fusion. Isothermal titration calorimetry (ITC) data showed that membrane fusion in our system is an exothermic process in the absence of cholesterol, suggesting that electrostatic attraction is the driving force for fusion. An endothermic component appeared and eventually dominated the titration at 30 mol % cholesterol, which we propose is caused by membrane fluidification when cholesterol is diluted upon fusion. The inflection points of the ITC data occurred around 0.5-0.7 POPG/DOTAP for all systems, the same stoichiometry for which zeta-potential and dynamic light scattering measurements showed an increase in size coupled with charge neutralization of the system, which is consistent with the fact that fusion in our system is charge-mediated. Microscopy observations of the final mixtures revealed the presence of giant vesicles, which is a clear indication of fusion, coexisting with intermediate-sized objects that could be the result of both fusion and/or aggregation. The results show that the fusion efficiency of the DOTAP:DOPE fusogenic system is modulated by the charge and membrane packing of the acceptor membrane and explain why the system fuses very efficiently with cells.
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Affiliation(s)
- Rafaela R M Cavalcanti
- Departamento de Biofísica, Universidade Federal de São Paulo, CEP 04039-032, São Paulo, Brazil
| | - Rafael B Lira
- Departamento de Biofísica, Universidade Federal de São Paulo, CEP 04039-032, São Paulo, Brazil
| | - Karin A Riske
- Departamento de Biofísica, Universidade Federal de São Paulo, CEP 04039-032, São Paulo, Brazil
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40
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Mukhina T, Brezesinski G, Schneck E. Phase Behavior and Miscibility in Two-Component Glycolipid Monolayers. J Phys Chem B 2022; 126:6464-6471. [PMID: 35976765 DOI: 10.1021/acs.jpcb.2c05016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Glycolipids are known to be involved in the formation of ordered functional domains in biological membranes. Since the structural characterization of such domains is difficult, most studies have so far dealt with lipid mixtures containing only one glycolipid component at a time, although biological membranes usually contain several glycolipid species, which can result in more complex structures and phase behavior. Here, we combine classical isotherm measurements with surface-sensitive grazing-incidence X-ray diffraction to investigate the phase behavior and miscibility in Langmuir monolayers of binary glycolipid mixtures. We find that the phase behavior has a subtle dependence on the saccharide headgroup chemistry. For compatible chemistries, molecular superlattice structures formed by one of the glycolipid species are conserved and can host foreign glycolipids up to a defined stoichiometry. In contrast, for sterically incompatible saccharide chemistries, the superlattice is lost even if both species are able to form such structures in their pure forms. Our results suggest that related phenomena may play important roles also in biological contexts.
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Affiliation(s)
- Tetiana Mukhina
- Institute for Condensed Matter Physics, TU Darmstadt, Hochschulstraße 8, 64289 Darmstadt, Germany
| | - Gerald Brezesinski
- Institute for Condensed Matter Physics, TU Darmstadt, Hochschulstraße 8, 64289 Darmstadt, Germany
| | - Emanuel Schneck
- Institute for Condensed Matter Physics, TU Darmstadt, Hochschulstraße 8, 64289 Darmstadt, Germany
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41
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Shrivastava S, Sarkar P, Preira P, Salomé L, Chattopadhyay A. Cholesterol-Dependent Dynamics of the Serotonin 1A Receptor Utilizing Single Particle Tracking: Analysis of Diffusion Modes. J Phys Chem B 2022; 126:6682-6690. [PMID: 35973070 DOI: 10.1021/acs.jpcb.2c03941] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
G protein-coupled receptors (GPCRs) are signaling hubs in cell membranes that regulate a wide range of physiological processes and are popular drug targets. Serotonin1A receptors are important members of the GPCR family and are implicated in neuropsychiatric disorders. Cholesterol is a key constituent of higher eukaryotic membranes and is believed to contribute to the segregated distribution of membrane constituents into domains. To explore the role of cholesterol in lateral dynamics of GPCRs, we utilized single particle tracking (SPT) to monitor diffusion of serotonin1A receptors under acute and chronic cholesterol-depleted conditions. Our results show that the short-term diffusion coefficient of the receptor decreases upon cholesterol depletion, irrespective of the method of cholesterol depletion. Analysis of SPT trajectories revealed that relative populations of receptors undergoing various modes of diffusion change upon cholesterol depletion. Notably, in cholesterol-depleted cells, we observed an increase in the confined population of the receptor accompanied by a reduction in diffusion coefficient for chronic cholesterol depletion. These results are supported by our recent work and present observations that show polymerization of G-actin in response to chronic cholesterol depletion. Taken together, our results bring out the interdependence of cholesterol and actin cytoskeleton in regulating diffusion of GPCRs in membranes.
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Affiliation(s)
- Sandeep Shrivastava
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India
| | - Parijat Sarkar
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India
| | - Pascal Preira
- Institut de Pharmacologie et de Biologie Structurale, CNRS, Université de Toulouse (UPS), 31 077 Toulouse, France
| | - Laurence Salomé
- Institut de Pharmacologie et de Biologie Structurale, CNRS, Université de Toulouse (UPS), 31 077 Toulouse, France
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42
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Sarkar P, Chattopadhyay A. Statin-induced Increase in Actin Polymerization Modulates GPCR Dynamics and Compartmentalization. Biophys J 2022:S0006-3495(22)00708-1. [DOI: 10.1016/j.bpj.2022.08.039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Revised: 07/16/2022] [Accepted: 08/25/2022] [Indexed: 11/29/2022] Open
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43
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Grusky DS, Moss FR, Boxer SG. Recombination between 13C and 2H to Form Acetylide ( 13C 22H -) Probes Nanoscale Interactions in Lipid Bilayers via Dynamic Secondary Ion Mass Spectrometry: Cholesterol and GM 1 Clustering. Anal Chem 2022; 94:9750-9757. [PMID: 35759338 PMCID: PMC10075087 DOI: 10.1021/acs.analchem.2c01336] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Although it is thought that there is lateral heterogeneity of lipid and protein components within biological membranes, probing this heterogeneity has proven challenging. The difficulty in such experiments is due to both the small length scale over which such heterogeneity can occur, and the significant perturbation resulting from fluorescent or spin labeling on the delicate interactions within bilayers. Atomic recombination during dynamic nanoscale secondary ion imaging mass spectrometry (NanoSIMS) is a non-perturbative method for examining nanoscale bilayer interactions. Atomic recombination is a variation on conventional NanoSIMS imaging, whereby an isotope on one molecule combines with a different isotope on another molecule during the ionization process, forming an isotopically enriched polyatomic ion in a distance-dependent manner. We show that the recombinant ion, 13C22H-, is formed in high yield from 13C- and 2H-labeled lipids. The low natural abundance of triply labeled acetylide also makes it an ideal ion to probe GM1 clusters in model membranes and the effects of cholesterol on lipid-lipid interactions. We find evidence supporting the cholesterol condensation effect as well as the presence of nanoscale GM1 clusters in model membranes.
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Affiliation(s)
- Dashiel S Grusky
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Frank R Moss
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | - Steven G Boxer
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
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44
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Barrantes FJ. The constellation of cholesterol-dependent processes associated with SARS-CoV-2 infection. Prog Lipid Res 2022; 87:101166. [PMID: 35513161 PMCID: PMC9059347 DOI: 10.1016/j.plipres.2022.101166] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Revised: 04/26/2022] [Accepted: 04/27/2022] [Indexed: 01/11/2023]
Abstract
The role of cholesterol in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and other coronavirus-host cell interactions is currently being discussed in the context of two main scenarios: i) the presence of the neutral lipid in cholesterol-rich lipid domains involved in different steps of the viral infection and ii) the alteration of metabolic pathways by the virus over the course of infection. Cholesterol-enriched lipid domains have been reported to occur in the lipid envelope membrane of the virus, in the host-cell plasma membrane, as well as in endosomal and other intracellular membrane cellular compartments. These membrane subdomains, whose chemical and physical properties distinguish them from the bulk lipid bilayer, have been purported to participate in diverse phenomena, from virus-host cell fusion to intracellular trafficking and exit of the virions from the infected cell. SARS-CoV-2 recruits many key proteins that participate under physiological conditions in cholesterol and lipid metabolism in general. This review analyses the status of cholesterol and lipidome proteins in SARS-CoV-2 infection and the new horizons they open for therapeutic intervention.
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Affiliation(s)
- Francisco J Barrantes
- Laboratory of Molecular Neurobiology, Institute for Biomedical Research (BIOMED), Faculty of Medical Sciences, UCA-CONICET, Av. Alicia Moreau de Justo 1600, C1107AFF Buenos Aires, Argentina.
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45
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Rudnicka M, Noszczyńska M, Malicka M, Kasperkiewicz K, Pawlik M, Piotrowska-Seget Z. Outer Membrane Vesicles as Mediators of Plant-Bacterial Interactions. Front Microbiol 2022; 13:902181. [PMID: 35722319 PMCID: PMC9198584 DOI: 10.3389/fmicb.2022.902181] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Accepted: 05/02/2022] [Indexed: 12/05/2022] Open
Abstract
Plants have co-evolved with diverse microorganisms that have developed different mechanisms of direct and indirect interactions with their host. Recently, greater attention has been paid to a direct "message" delivery pathway from bacteria to plants, mediated by the outer membrane vesicles (OMVs). OMVs produced by Gram-negative bacteria play significant roles in multiple interactions with other bacteria within the same community, the environment, and colonized hosts. The combined forces of innovative technologies and experience in the area of plant-bacterial interactions have put pressure on a detailed examination of the OMVs composition, the routes of their delivery to plant cells, and their significance in pathogenesis, protection, and plant growth promotion. This review synthesizes the available knowledge on OMVs in the context of possible mechanisms of interactions between OMVs, bacteria, and plant cells. OMVs are considered to be potential stimulators of the plant immune system, holding potential for application in plant bioprotection.
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Affiliation(s)
| | | | - Monika Malicka
- Institute of Biology, Biotechnology and Environmental Protection, Faculty of Natural Sciences, University of Silesia in Katowice, Katowice, Poland
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46
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Wagner AM, Quandt J, Söder D, Garay‐Sarmiento M, Joseph A, Petrovskii VS, Witzdam L, Hammoor T, Steitz P, Haraszti T, Potemkin II, Kostina NY, Herrmann A, Rodriguez‐Emmenegger C. Ionic Combisomes: A New Class of Biomimetic Vesicles to Fuse with Life. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2022; 9:e2200617. [PMID: 35393756 PMCID: PMC9189634 DOI: 10.1002/advs.202200617] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 03/03/2022] [Indexed: 06/14/2023]
Abstract
The construction of biomembranes that faithfully capture the properties and dynamic functions of cell membranes remains a challenge in the development of synthetic cells and their application. Here a new concept for synthetic cell membranes based on the self-assembly of amphiphilic comb polymers into vesicles, termed ionic combisomes (i-combisomes) is introduced. These combs consist of a polyzwitterionic backbone to which hydrophobic tails are linked by electrostatic interactions. Using a range of microscopies and molecular simulations, the self-assembly of a library of combs in water is screened. It is discovered that the hydrophobic tails form the membrane's core and force the backbone into a rod conformation with nematic-like ordering confined to the interface with water. This particular organization resulted in membranes that combine the stability of classic polymersomes with the biomimetic thickness, flexibility, and lateral mobility of liposomes. Such unparalleled matching of biophysical properties and the ability to locally reconfigure the molecular topology of its constituents enable the harboring of functional components of natural membranes and fusion with living bacteria to "hijack" their periphery. This provides an almost inexhaustible palette to design the chemical and biological makeup of the i-combisomes membrane resulting in a powerful platform for fundamental studies and technological applications.
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Affiliation(s)
- Anna M. Wagner
- DWI – Leibniz Institute for Interactive MaterialsForckenbeckstraße 50Aachen52074Germany
- Institute of Technical and Macromolecular ChemistryRWTH Aachen UniversityWorringerweg 2Aachen52074Germany
| | - Jonas Quandt
- DWI – Leibniz Institute for Interactive MaterialsForckenbeckstraße 50Aachen52074Germany
- Institute of Technical and Macromolecular ChemistryRWTH Aachen UniversityWorringerweg 2Aachen52074Germany
| | - Dominik Söder
- DWI – Leibniz Institute for Interactive MaterialsForckenbeckstraße 50Aachen52074Germany
- Institute of Technical and Macromolecular ChemistryRWTH Aachen UniversityWorringerweg 2Aachen52074Germany
| | - Manuela Garay‐Sarmiento
- DWI – Leibniz Institute for Interactive MaterialsForckenbeckstraße 50Aachen52074Germany
- Chair of BiotechnologyRWTH Aachen UniversityWorringerweg 3Aachen52074Germany
| | - Anton Joseph
- DWI – Leibniz Institute for Interactive MaterialsForckenbeckstraße 50Aachen52074Germany
- Institute of Technical and Macromolecular ChemistryRWTH Aachen UniversityWorringerweg 2Aachen52074Germany
| | - Vladislav S. Petrovskii
- Physics DepartmentLomonosov Moscow State UniversityLeninskie Gory 1–2Moscow119991Russian Federation
| | - Lena Witzdam
- DWI – Leibniz Institute for Interactive MaterialsForckenbeckstraße 50Aachen52074Germany
- Institute of Technical and Macromolecular ChemistryRWTH Aachen UniversityWorringerweg 2Aachen52074Germany
| | - Thomas Hammoor
- DWI – Leibniz Institute for Interactive MaterialsForckenbeckstraße 50Aachen52074Germany
| | - Philipp Steitz
- DWI – Leibniz Institute for Interactive MaterialsForckenbeckstraße 50Aachen52074Germany
| | - Tamás Haraszti
- DWI – Leibniz Institute for Interactive MaterialsForckenbeckstraße 50Aachen52074Germany
| | - Igor I. Potemkin
- DWI – Leibniz Institute for Interactive MaterialsForckenbeckstraße 50Aachen52074Germany
- Physics DepartmentLomonosov Moscow State UniversityLeninskie Gory 1–2Moscow119991Russian Federation
- National Research, South Ural State UniversityChelyabinsk454080Russian Federation
| | - Nina Yu. Kostina
- DWI – Leibniz Institute for Interactive MaterialsForckenbeckstraße 50Aachen52074Germany
- Institute of Technical and Macromolecular ChemistryRWTH Aachen UniversityWorringerweg 2Aachen52074Germany
| | - Andreas Herrmann
- DWI – Leibniz Institute for Interactive MaterialsForckenbeckstraße 50Aachen52074Germany
- Institute of Technical and Macromolecular ChemistryRWTH Aachen UniversityWorringerweg 2Aachen52074Germany
| | - Cesar Rodriguez‐Emmenegger
- DWI – Leibniz Institute for Interactive MaterialsForckenbeckstraße 50Aachen52074Germany
- Institute for Bioengineering of Catalonia (IBEC)Carrer de Baldiri Reixac, 10, 12Barcelona08028Spain
- Institució Catalana de Recerca i Estudis Avançats (ICREA)Passeig Lluís Companys 23Barcelona08010Spain
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47
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Barrantes FJ. Fluorescence Studies of Nicotinic Acetylcholine Receptor and Its Associated Lipid Milieu: The Influence of Erwin London's Methodological Approaches. J Membr Biol 2022; 255:563-574. [PMID: 35534578 DOI: 10.1007/s00232-022-00239-9] [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: 02/17/2022] [Accepted: 04/11/2022] [Indexed: 11/29/2022]
Abstract
Erwin London dedicated considerable effort to understanding lipid interactions with membrane-resident proteins and how these interactions shaped the formation and maintenance of lipid phases and domains. In this endeavor, he developed ad hoc techniques that greatly contributed to advancements in the field. We have employed and/or modified/extended some of his methodological approaches and applied them to investigate lipid interaction with the nicotinic acetylcholine receptor (nAChR) protein, the paradigm member of the superfamily of rapid pentameric ligand-gated ion channels (pLGIC). Our experimental systems ranged from purified receptor protein reconstituted into synthetic lipid membranes having known effects on receptor function, to cellular systems subjected to modification of their lipid content, e.g., varying cholesterol levels. We have often employed fluorescence techniques, including fluorescence quenching of diphenylhexatriene (DPH) extrinsic fluorescence and of nAChR intrinsic fluorescence by nitroxide spin-labeled phospholipids, DPH anisotropy, excimer formation of pyrene-phosphatidylcholine, and Förster resonance energy transfer (FRET) from the protein moiety to the extrinsic probes Laurdan, DPH, or pyrene-phospholipid to characterize various biophysical properties of lipid-receptor interactions. Some of these strategies are revisited in this review. Special attention is devoted to the anionic phospholipid phosphatidic acid (PA), which stabilizes the functional resting form of the nAChR. The receptor protein was shown to organize its PA-containing immediate microenvironment into microdomains with high lateral packing density and rigidity. PA and cholesterol appear to compete for the same binding sites on the nAChR protein.
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Affiliation(s)
- Francisco J Barrantes
- Laboratory of Molecular Neurobiology, Institute of Biomedical Research (BIOMED), UCA-CONICET, Av. Alicia Moreau de Justo 1600, C1107AFF, Buenos Aires, Argentina.
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48
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Shrestha A, Kahraman O, Haselwandter CA. Mechanochemical coupling of lipid organization and protein function through membrane thickness deformations. Phys Rev E 2022; 105:054410. [PMID: 35706253 DOI: 10.1103/physreve.105.054410] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Accepted: 05/06/2022] [Indexed: 06/15/2023]
Abstract
Cell membranes are composed of a great variety of protein and lipid species with distinct unperturbed hydrophobic thicknesses. To achieve hydrophobic matching, the lipid bilayer tends to deform around membrane proteins so as to match the protein hydrophobic thickness at bilayer-protein interfaces. Such protein-induced distortions of the lipid bilayer hydrophobic thickness incur a substantial energy cost that depends critically on the bilayer-protein hydrophobic mismatch, while distinct conformational states of membrane proteins often show distinct hydrophobic thicknesses. As a result, hydrophobic interactions between membrane proteins and lipids can yield a rich interplay of lipid-protein organization and transitions in protein conformational state. We combine here the membrane elasticity theory of protein-induced lipid bilayer thickness deformations with the Landau-Ginzburg theory of lipid domain formation to systematically explore the coupling between local lipid organization, lipid and protein hydrophobic thickness, and protein-induced lipid bilayer thickness deformations in membranes with heterogeneous lipid composition. We allow for a purely mechanical coupling of lipid and protein composition through the energetics of protein-induced lipid bilayer thickness deformations as well as a chemical coupling driven by preferential interactions between particular lipid and protein species. We find that the resulting lipid-protein organization can endow membrane proteins with diverse and controlled mechanical environments that, via protein-induced lipid bilayer thickness deformations, can strongly influence protein function. The theoretical approach employed here provides a general framework for the quantitative prediction of how membrane thickness deformations influence the joint organization and function of lipids and proteins in cell membranes.
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Affiliation(s)
- Ahis Shrestha
- Department of Physics and Astronomy and Department of Quantitative and Computational Biology, University of Southern California, Los Angeles, California 90089, USA
| | - Osman Kahraman
- Department of Physics and Astronomy and Department of Quantitative and Computational Biology, University of Southern California, Los Angeles, California 90089, USA
| | - Christoph A Haselwandter
- Department of Physics and Astronomy and Department of Quantitative and Computational Biology, University of Southern California, Los Angeles, California 90089, USA
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49
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Sarkar P, Kumar GA, Shrivastava S, Chattopadhyay A. Chronic cholesterol depletion increases F-actin levels and induces cytoskeletal reorganization via a dual mechanism. J Lipid Res 2022; 63:100206. [PMID: 35390404 PMCID: PMC9096963 DOI: 10.1016/j.jlr.2022.100206] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 03/22/2022] [Accepted: 03/28/2022] [Indexed: 12/24/2022] Open
Abstract
Previous work from us and others has suggested that cholesterol is an important lipid in the context of the organization of the actin cytoskeleton. However, reorganization of the actin cytoskeleton upon modulation of membrane cholesterol is rarely addressed in the literature. In this work, we explored the signaling crosstalk between cholesterol and the actin cytoskeleton by using a high-resolution confocal microscopic approach to quantitatively measure changes in F-actin content upon cholesterol depletion. Our results show that F-actin content significantly increases upon chronic cholesterol depletion, but not during acute cholesterol depletion. In addition, utilizing inhibitors targeting the cholesterol biosynthetic pathway at different steps, we show that reorganization of the actin cytoskeleton could occur due to the synergistic effect of multiple pathways, including prenylated Rho GTPases and availability of membrane phosphatidylinositol 4,5-bisphosphate. These results constitute one of the first comprehensive dissections of the mechanistic basis underlying the interplay between cellular actin levels and cholesterol biosynthesis. We envision these results will be relevant for future understating of the remodeling of the actin cytoskeleton in pathological conditions with altered cholesterol.
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Affiliation(s)
- Parijat Sarkar
- CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India
| | - G Aditya Kumar
- CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India
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50
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Schnitzler LG, Baumgartner K, Kolb A, Braun B, Westerhausen C. Acetylcholinesterase Activity Influenced by Lipid Membrane Area and Surface Acoustic Waves. MICROMACHINES 2022; 13:mi13020287. [PMID: 35208411 PMCID: PMC8877910 DOI: 10.3390/mi13020287] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Revised: 02/03/2022] [Accepted: 02/07/2022] [Indexed: 12/10/2022]
Abstract
According to the current model of nerve propagation, the function of acetylcholinesterase (AChE) is to terminate synaptic transmission of nerve signals by hydrolyzing the neurotransmitter acetylcholine (ACh) in the synaptic cleft to acetic acid (acetate) and choline. However, extra-synaptic roles, which are known as ‘non-classical’ roles, have not been fully elucidated. Here, we measured AChE activity with the enzyme bound to lipid membranes of varying area per enzyme in vitro using the Ellman assay. We found that the activity was not affected by density fluctuations in a supported lipid bilayer (SLB) induced by standing surface acoustic waves. Nevertheless, we found twice as high activity in the presence of small unilamellar vesicles (SUV) compared to lipid-free samples. We also showed that the increase in activity scaled with the available membrane area per enzyme.
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Affiliation(s)
- Lukas G. Schnitzler
- Experimental Physics I, Institute of Physics, University of Augsburg, 86159 Augsburg, Germany; (L.G.S.); (K.B.); (A.K.); (B.B.)
- Center for NanoScience (CeNS), Ludwig-Maximilians-Universität Munich, 80799 Munich, Germany
| | - Kathrin Baumgartner
- Experimental Physics I, Institute of Physics, University of Augsburg, 86159 Augsburg, Germany; (L.G.S.); (K.B.); (A.K.); (B.B.)
- Center for NanoScience (CeNS), Ludwig-Maximilians-Universität Munich, 80799 Munich, Germany
- Physiology, Institute of Theoretical Medicine, University of Augsburg, 86159 Augsburg, Germany
| | - Anna Kolb
- Experimental Physics I, Institute of Physics, University of Augsburg, 86159 Augsburg, Germany; (L.G.S.); (K.B.); (A.K.); (B.B.)
| | - Benedikt Braun
- Experimental Physics I, Institute of Physics, University of Augsburg, 86159 Augsburg, Germany; (L.G.S.); (K.B.); (A.K.); (B.B.)
| | - Christoph Westerhausen
- Center for NanoScience (CeNS), Ludwig-Maximilians-Universität Munich, 80799 Munich, Germany
- Physiology, Institute of Theoretical Medicine, University of Augsburg, 86159 Augsburg, Germany
- Augsburg Center for Innovative Technologies (ACIT), 86159 Augsburg, Germany
- Correspondence:
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