1
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Erguven H, Wang L, Gutierrez B, Beaven AH, Sodt AJ, Izgu EC. Biomimetic Vesicles with Designer Phospholipids Can Sense Environmental Redox Cues. JACS AU 2024; 4:1841-1853. [PMID: 38818047 PMCID: PMC11134385 DOI: 10.1021/jacsau.4c00041] [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: 01/09/2024] [Revised: 03/06/2024] [Accepted: 03/26/2024] [Indexed: 06/01/2024]
Abstract
Cell-like materials that sense environmental cues can serve as next-generation biosensors and help advance the understanding of intercellular communication. Currently, bottom-up engineering of protocell models from molecular building blocks remains a grand challenge chemists face. Herein, we describe giant unilamellar vesicles (GUVs) with biomimetic lipid membranes capable of sensing environmental redox cues. The GUVs employ activity-based sensing through designer phospholipids that are fluorescently activated in response to specific reductive (hydrogen sulfide) or oxidative (hydrogen peroxide) conditions. These synthetic phospholipids are derived from 1,2-dipalmitoyl-rac-glycero-3-phosphocholine and they possess a headgroup with heterocyclic aromatic motifs. Despite their structural deviation from the phosphocholine headgroup, the designer phospholipids (0.5-1.0 mol %) mixed with natural lipids can vesiculate, and the resulting GUVs (7-20 μm in diameter) remain intact over the course of redox sensing. All-atom molecular dynamics simulations gave insight into how these lipids are positioned within the hydrophobic core of the membrane bilayer and at the membrane-water interface. This work provides a purely chemical method to investigate potential redox signaling and opens up new design opportunities for soft materials that mimic protocells.
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Affiliation(s)
- Huseyin Erguven
- Department
of Chemistry and Chemical Biology, Rutgers
University, New Brunswick, New Jersey 08854, United States
| | - Liming Wang
- Department
of Chemistry and Chemical Biology, Rutgers
University, New Brunswick, New Jersey 08854, United States
| | - Bryan Gutierrez
- Department
of Chemistry and Chemical Biology, Rutgers
University, New Brunswick, New Jersey 08854, United States
| | - Andrew H. Beaven
- Unit
on Membrane Chemical Physics, Eunice Kennedy Shriver National Institute
of Child Health and Human Development, National
Institutes of Health, Bethesda, Maryland 20892, United States
- Postdoctoral
Research Associate Program, National Institute
of General Medical Sciences, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Alexander J. Sodt
- Unit
on Membrane Chemical Physics, Eunice Kennedy Shriver National Institute
of Child Health and Human Development, National
Institutes of Health, Bethesda, Maryland 20892, United States
| | - Enver Cagri Izgu
- Department
of Chemistry and Chemical Biology, Rutgers
University, New Brunswick, New Jersey 08854, United States
- Cancer
Institute of New Jersey, Rutgers University, New Brunswick, New Jersey 08901, United States
- Rutgers
Center for Lipid Research, New Jersey Institute
for Food, Nutrition, and Health, Rutgers University, New Brunswick, New Jersey 08901, United States
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2
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Ragaller F, Sjule E, Urem YB, Schlegel J, El R, Urbancic D, Urbancic I, Blom H, Sezgin E. Quantifying Fluorescence Lifetime Responsiveness of Environment-Sensitive Probes for Membrane Fluidity Measurements. J Phys Chem B 2024; 128:2154-2167. [PMID: 38415644 PMCID: PMC10926104 DOI: 10.1021/acs.jpcb.3c07006] [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: 10/23/2023] [Revised: 02/08/2024] [Accepted: 02/09/2024] [Indexed: 02/29/2024]
Abstract
The structural diversity of different lipid species within the membrane defines its biophysical properties such as membrane fluidity, phase transition, curvature, charge distribution, and tension. Environment-sensitive probes, which change their spectral properties in response to their surrounding milieu, have greatly contributed to our understanding of such biophysical properties. To realize the full potential of these probes and avoid misinterpretation of their spectral responses, a detailed investigation of their fluorescence characteristics in different environments is necessary. Here, we examined the fluorescence lifetime of two newly developed membrane order probes, NR12S and NR12A, in response to alterations in their environments such as the degree of lipid saturation, cholesterol content, double bond position and configuration, and phospholipid headgroup. As a comparison, we investigated the lifetime sensitivity of the membrane tension probe Flipper in these environments. Applying fluorescence lifetime imaging microscopy (FLIM) in both model membranes and biological membranes, all probes distinguished membrane phases by lifetime but exhibited different lifetime sensitivities to varying membrane biophysical properties (e.g., cholesterol). While the lifetime of Flipper is particularly sensitive to the membrane cholesterol content, the NR12S and NR12A lifetimes are moderately sensitive to both the cholesterol content and lipid acyl chains. Moreover, all of the probes exhibit longer lifetimes at longer emission wavelengths in membranes of any complexity. This emission wavelength dependency results in varying lifetime resolutions at different spectral regions, which are highly relevant for FLIM data acquisition. Our data provide valuable insights on how to perform FLIM with these probes and highlight both their potential and limitations.
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Affiliation(s)
- Franziska Ragaller
- Department
of Women’s and Children’s Health, Science for Life Laboratory, Karolinska Institutet, 17165 Solna, Sweden
| | - Ellen Sjule
- Department
of Women’s and Children’s Health, Science for Life Laboratory, Karolinska Institutet, 17165 Solna, Sweden
| | - Yagmur Balim Urem
- Department
of Women’s and Children’s Health, Science for Life Laboratory, Karolinska Institutet, 17165 Solna, Sweden
| | - Jan Schlegel
- Department
of Women’s and Children’s Health, Science for Life Laboratory, Karolinska Institutet, 17165 Solna, Sweden
| | - Rojbin El
- Weatherall
Institute of Molecular Medicine, University
of Oxford, OX39DS Oxford, United
Kingdom
| | - Dunja Urbancic
- Weatherall
Institute of Molecular Medicine, University
of Oxford, OX39DS Oxford, United
Kingdom
- Faculty
of Pharmacy, University
of Ljubljana, 1000 Ljubljana, Slovenia
| | - Iztok Urbancic
- Laboratory
of Biophysics, Condensed Matter Physics Department, Jožef Stefan Institute, 1000 Ljubljana, Slovenia
| | - Hans Blom
- Science
for Life Laboratory, Department of Applied Physics, Royal Institute of Technology, 17165 Solna, Sweden
| | - Erdinc Sezgin
- Department
of Women’s and Children’s Health, Science for Life Laboratory, Karolinska Institutet, 17165 Solna, Sweden
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3
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Cawley J, Berger BA, Odudimu AT, Singh AN, Santa DE, McDarby AI, Honerkamp-Smith AR, Wittenberg NJ. Imaging Giant Vesicle Membrane Domains with a Luminescent Europium Tetracycline Complex. ACS OMEGA 2023; 8:29314-29323. [PMID: 37599986 PMCID: PMC10433515 DOI: 10.1021/acsomega.3c02721] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Accepted: 07/24/2023] [Indexed: 08/22/2023]
Abstract
Microdomains in lipid bilayer membranes are routinely imaged using organic fluorophores that preferentially partition into one of the lipid phases, resulting in fluorescence contrast. Here, we show that membrane microdomains in giant unilamellar vesicles (GUVs) can be visualized with europium luminescence using a complex of europium III (Eu3+) and tetracycline (EuTc). EuTc is unlike typical organic lipid probes in that it is a coordination complex with a unique excitation/emission wavelength combination (396/617 nm), a very large Stokes shift (221 nm), and a very narrow emission bandwidth (8 nm). The probe preferentially interacts with liquid disordered domains in GUVs, which results in intensity contrast across the surface of phase-separated GUVs. Interestingly, EuTc also alters GM1 ganglioside partitioning. GM1 typically partitions into liquid ordered domains, but after labeling phase-separated GUVs with EuTc, cholera toxin B-subunit (CTxB), which binds GM1, labels liquid disordered domains. We also demonstrate that EuTc, but not free Eu3+ or Tc, significantly reduces lipid diffusion coefficients. Finally, we show that EuTc can be used to label cellular membranes similar to a traditional membrane probe. EuTc may find utility as a membrane imaging probe where its large Stokes shift and sharp emission band would enable multicolor imaging.
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Affiliation(s)
- Jennie
L. Cawley
- Department
of Chemistry, Lehigh University, 6 East Packer Avenue, Bethlehem, Pennsylvania 18015, United States
| | - Brett A. Berger
- Department
of Chemistry, Lehigh University, 6 East Packer Avenue, Bethlehem, Pennsylvania 18015, United States
| | - Adeyemi T. Odudimu
- Department
of Chemistry, Lehigh University, 6 East Packer Avenue, Bethlehem, Pennsylvania 18015, United States
| | - Aarshi N. Singh
- Department
of Chemistry, Lehigh University, 6 East Packer Avenue, Bethlehem, Pennsylvania 18015, United States
| | - Dane E. Santa
- Department
of Chemistry, Lehigh University, 6 East Packer Avenue, Bethlehem, Pennsylvania 18015, United States
| | - Ariana I. McDarby
- Department
of Chemistry, Lehigh University, 6 East Packer Avenue, Bethlehem, Pennsylvania 18015, United States
| | - Aurelia R. Honerkamp-Smith
- Department
of Physics, Lehigh University, 17 Memorial Drive East, Bethlehem, Pennsylvania 18015, United States
| | - Nathan J. Wittenberg
- Department
of Chemistry, Lehigh University, 6 East Packer Avenue, Bethlehem, Pennsylvania 18015, United States
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4
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He S, Qiu S, Pan M, Palavicini JP, Wang H, Li X, Bhattacharjee A, Barannikov S, Bieniek KF, Dupree JL, Han X. Central nervous system sulfatide deficiency as a causal factor for bladder disorder in Alzheimer's disease. Clin Transl Med 2023; 13:e1332. [PMID: 37478300 PMCID: PMC10361545 DOI: 10.1002/ctm2.1332] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Revised: 07/02/2023] [Accepted: 07/10/2023] [Indexed: 07/23/2023] Open
Abstract
BACKGROUND Despite being a brain disorder, Alzheimer's disease (AD) is often accompanied by peripheral organ dysregulations (e.g., loss of bladder control in late-stage AD), which highly rely on spinal cord coordination. However, the causal factor(s) for peripheral organ dysregulation in AD remain elusive. METHODS The central nervous system (CNS) is enriched in lipids. We applied quantitative shotgun lipidomics to determine lipid profiles of human AD spinal cord tissues. Additionally, a CNS sulfatide (ST)-deficient mouse model was used to study the lipidome, transcriptome and peripheral organ phenotypes of ST loss. RESULTS We observed marked myelin lipid reduction in the spinal cord of AD subjects versus cognitively normal individuals. Among which, levels of ST, a myelin-enriched lipid class, were strongly and negatively associated with the severity of AD. A CNS myelin-specific ST-deficient mouse model was used to further identify the causes and consequences of spinal cord lipidome changes. Interestingly, ST deficiency led to spinal cord lipidome and transcriptome profiles highly resembling those observed in AD, characterized by decline of multiple myelin-enriched lipid classes and enhanced inflammatory responses, respectively. These changes significantly disrupted spinal cord function and led to substantial enlargement of urinary bladder in ST-deficient mice. CONCLUSIONS Our study identified CNS ST deficiency as a causal factor for AD-like lipid dysregulation, inflammation response and ultimately the development of bladder disorders. Targeting to maintain ST levels may serve as a promising strategy for the prevention and treatment of AD-related peripheral disorders.
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Affiliation(s)
- Sijia He
- Barshop Institute for Longevity and Aging StudiesUniversity of Texas Health San AntonioSan AntonioTexasUSA
| | - Shulan Qiu
- Barshop Institute for Longevity and Aging StudiesUniversity of Texas Health San AntonioSan AntonioTexasUSA
| | - Meixia Pan
- Barshop Institute for Longevity and Aging StudiesUniversity of Texas Health San AntonioSan AntonioTexasUSA
| | - Juan P. Palavicini
- Barshop Institute for Longevity and Aging StudiesUniversity of Texas Health San AntonioSan AntonioTexasUSA
- Division of DiabetesDepartment of MedicineUniversity of Texas Health San AntonioSan AntonioTexasUSA
| | - Hu Wang
- Barshop Institute for Longevity and Aging StudiesUniversity of Texas Health San AntonioSan AntonioTexasUSA
| | - Xin Li
- Barshop Institute for Longevity and Aging StudiesUniversity of Texas Health San AntonioSan AntonioTexasUSA
| | - Anindita Bhattacharjee
- Barshop Institute for Longevity and Aging StudiesUniversity of Texas Health San AntonioSan AntonioTexasUSA
| | - Savannah Barannikov
- Department of PathologyGlenn Biggs Institute for Alzheimer's and Neurodegenerative DiseasesUniversity of Texas Health San AntonioSan AntonioTexasUSA
| | - Kevin F. Bieniek
- Department of PathologyGlenn Biggs Institute for Alzheimer's and Neurodegenerative DiseasesUniversity of Texas Health San AntonioSan AntonioTexasUSA
| | - Jeffrey L. Dupree
- Department of Anatomy and NeurobiologyVirginia Commonwealth UniversityRichmondVirginiaUSA
- Research DivisionMcGuire Veterans Affairs Medical CenterRichmondVirginiaUSA
| | - Xianlin Han
- Barshop Institute for Longevity and Aging StudiesUniversity of Texas Health San AntonioSan AntonioTexasUSA
- Division of DiabetesDepartment of MedicineUniversity of Texas Health San AntonioSan AntonioTexasUSA
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5
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Zhou Y, Hancock JF. RAS nanoclusters are cell surface transducers that convert extracellular stimuli to intracellular signalling. FEBS Lett 2023; 597:892-908. [PMID: 36595205 PMCID: PMC10919257 DOI: 10.1002/1873-3468.14569] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Revised: 12/05/2022] [Accepted: 12/12/2022] [Indexed: 01/04/2023]
Abstract
Mutations of rat sarcoma virus (RAS) oncogenes (HRAS, KRAS and NRAS) can contribute to the development of cancers and genetic disorders (RASopathies). The spatiotemporal organization of RAS is an important property that warrants further investigation. In order to function, wild-type or oncogenic mutants of RAS must be localized to the inner leaflet of the plasma membrane (PM), which is driven by interactions between their C-terminal membrane-anchoring domains and PM lipids. The isoform-specific RAS-lipid interactions promote the formation of nanoclusters on the PM. As main sites for effector recruitment, these nanoclusters are biologically important. Since the spatial distribution of lipids is sensitive to changing environments, such as mechanical and electrical perturbations, RAS nanoclusters act as transducers to convert external stimuli to intracellular mitogenic signalling. As such, effective inhibition of RAS oncogenesis requires consideration of the complex interplay between RAS nanoclusters and various cell surface and extracellular stimuli. In this review, we discuss in detail how, by sorting specific lipids in the PM, RAS nanoclusters act as transducers to convert external stimuli into intracellular signalling.
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Affiliation(s)
- Yong Zhou
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston, McGovern Medical School, TX, USA
- Graduate School of Biomedical Sciences, University of Texas MD Anderson Cancer Center and University of Texas Health Science Center, TX, USA
| | - John F Hancock
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston, McGovern Medical School, TX, USA
- Graduate School of Biomedical Sciences, University of Texas MD Anderson Cancer Center and University of Texas Health Science Center, TX, USA
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6
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Margheritis E, Kappelhoff S, Cosentino K. Pore-Forming Proteins: From Pore Assembly to Structure by Quantitative Single-Molecule Imaging. Int J Mol Sci 2023; 24:ijms24054528. [PMID: 36901959 PMCID: PMC10003378 DOI: 10.3390/ijms24054528] [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: 01/05/2023] [Revised: 02/11/2023] [Accepted: 02/21/2023] [Indexed: 03/03/2023] Open
Abstract
Pore-forming proteins (PFPs) play a central role in many biological processes related to infection, immunity, cancer, and neurodegeneration. A common feature of PFPs is their ability to form pores that disrupt the membrane permeability barrier and ion homeostasis and generally induce cell death. Some PFPs are part of the genetically encoded machinery of eukaryotic cells that are activated against infection by pathogens or in physiological programs to carry out regulated cell death. PFPs organize into supramolecular transmembrane complexes that perforate membranes through a multistep process involving membrane insertion, protein oligomerization, and finally pore formation. However, the exact mechanism of pore formation varies from PFP to PFP, resulting in different pore structures with different functionalities. Here, we review recent insights into the molecular mechanisms by which PFPs permeabilize membranes and recent methodological advances in their characterization in artificial and cellular membranes. In particular, we focus on single-molecule imaging techniques as powerful tools to unravel the molecular mechanistic details of pore assembly that are often obscured by ensemble measurements, and to determine pore structure and functionality. Uncovering the mechanistic elements of pore formation is critical for understanding the physiological role of PFPs and developing therapeutic approaches.
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7
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Krompers M, Heerklotz H. A Guide to Your Desired Lipid-Asymmetric Vesicles. MEMBRANES 2023; 13:267. [PMID: 36984654 PMCID: PMC10054703 DOI: 10.3390/membranes13030267] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 02/14/2023] [Accepted: 02/18/2023] [Indexed: 06/18/2023]
Abstract
Liposomes are prevalent model systems for studies on biological membranes. Recently, increasing attention has been paid to models also representing the lipid asymmetry of biological membranes. Here, we review in-vitro methods that have been established to prepare free-floating vesicles containing different compositions of the classic two-chain glycero- or sphingolipids in their outer and inner leaflet. In total, 72 reports are listed and assigned to four general strategies that are (A) enzymatic conversion of outer leaflet lipids, (B) re-sorting of lipids between leaflets, (C) assembly from different monolayers and (D) exchange of outer leaflet lipids. To guide the reader through this broad field of available techniques, we attempt to draw a road map that leads to the lipid-asymmetric vesicles that suit a given purpose. Of each method, we discuss advantages and limitations. In addition, various verification strategies of asymmetry as well as the role of cholesterol are briefly discussed. The ability to specifically induce lipid asymmetry in model membranes offers insights into the biological functions of asymmetry and may also benefit the technical applications of liposomes.
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Affiliation(s)
- Mona Krompers
- Department of Pharmaceutical Technology and Biopharmacy, Institute for Pharmaceutical Sciences, University of Freiburg, 79104 Freiburg im Breisgau, Germany
| | - Heiko Heerklotz
- Department of Pharmaceutical Technology and Biopharmacy, Institute for Pharmaceutical Sciences, University of Freiburg, 79104 Freiburg im Breisgau, Germany
- Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, ON M5S 3M2, Canada
- Signalling Research Centers BIOSS and CIBSS, University of Freiburg, 79085 Freiburg im Breisgau, Germany
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8
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Duncan AL, Pezeshkian W. Mesoscale simulations: An indispensable approach to understand biomembranes. Biophys J 2023:S0006-3495(23)00123-6. [PMID: 36809878 DOI: 10.1016/j.bpj.2023.02.017] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 12/10/2022] [Accepted: 02/13/2023] [Indexed: 02/23/2023] Open
Abstract
Computer simulation techniques form a versatile tool, a computational microscope, for exploring biological processes. This tool has been particularly effective in exploring different features of biological membranes. In recent years, thanks to elegant multiscale simulation schemes, some fundamental limitations of investigations by distinct simulation techniques have been resolved. As a result, we are now capable of exploring processes spanning multiple scales beyond the capacity of any single technique. In this perspective, we argue that mesoscale simulations require more attention and must be further developed to fill evident gaps in a quest toward simulating and modeling living cell membranes.
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Affiliation(s)
- Anna L Duncan
- Department of Chemistry, Aarhus University, Aarhus C, Denmark.
| | - Weria Pezeshkian
- Niels Bohr International Academy, Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark.
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9
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McAffee DB, O'Dair MK, Lin JJ, Low-Nam ST, Wilhelm KB, Kim S, Morita S, Groves JT. Discrete LAT condensates encode antigen information from single pMHC:TCR binding events. Nat Commun 2022; 13:7446. [PMID: 36460640 PMCID: PMC9718779 DOI: 10.1038/s41467-022-35093-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2022] [Accepted: 11/17/2022] [Indexed: 12/05/2022] Open
Abstract
LAT assembly into a two-dimensional protein condensate is a prominent feature of antigen discrimination by T cells. Here, we use single-molecule imaging techniques to resolve the spatial position and temporal duration of each pMHC:TCR molecular binding event while simultaneously monitoring LAT condensation at the membrane. An individual binding event is sufficient to trigger a LAT condensate, which is self-limiting, and neither its size nor lifetime is correlated with the duration of the originating pMHC:TCR binding event. Only the probability of the LAT condensate forming is related to the pMHC:TCR binding dwell time. LAT condenses abruptly, but after an extended delay from the originating binding event. A LAT mutation that facilitates phosphorylation at the PLC-γ1 recruitment site shortens the delay time to LAT condensation and alters T cell antigen specificity. These results identify a function for the LAT protein condensation phase transition in setting antigen discrimination thresholds in T cells.
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Affiliation(s)
- Darren B McAffee
- Department of Chemistry, University of California, Berkeley, Berkeley, CA, 94720, USA
| | - Mark K O'Dair
- Department of Chemistry, University of California, Berkeley, Berkeley, CA, 94720, USA
| | - Jenny J Lin
- Department of Chemistry, University of California, Berkeley, Berkeley, CA, 94720, USA
| | - Shalini T Low-Nam
- Department of Chemistry, University of California, Berkeley, Berkeley, CA, 94720, USA
| | - Kiera B Wilhelm
- Department of Chemistry, University of California, Berkeley, Berkeley, CA, 94720, USA
| | - Sungi Kim
- Department of Chemistry, University of California, Berkeley, Berkeley, CA, 94720, USA
| | - Shumpei Morita
- Department of Chemistry, University of California, Berkeley, Berkeley, CA, 94720, USA
| | - Jay T Groves
- Department of Chemistry, University of California, Berkeley, Berkeley, CA, 94720, USA.
- Institute for Digital Molecular Analytics and Science, Nanyang Technological University, 59 Nanyang Drive, Singapore, 636921, Singapore.
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10
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Kramer K, Sari M, Schulze K, Flegel H, Stehr M, Mey I, Janshoff A, Steinem C. From LUVs to GUVs─How to Cover Micrometer-Sized Pores with Membranes. J Phys Chem B 2022; 126:8233-8244. [PMID: 36210780 DOI: 10.1021/acs.jpcb.2c05685] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Pore-spanning membranes (PSMs) are a versatile tool to investigate membrane-confined processes in a bottom-up approach. Pore sizes in the micrometer range are most suited to visualize PSMs using fluorescence microscopy. However, the preparation of these PSMs relies on the spreading of giant unilamellar vesicles (GUVs). GUV production faces several limitations. Thus, alternative ways to generate PSMs starting from large or small unilamellar vesicles that are more reproducibly prepared are highly desirable. Here we describe a method to produce PSMs obtained from large unilamellar vesicles, making use of droplet-stabilized GUVs generated in a microfluidic device. We analyzed the lipid diffusion in the free-standing and supported parts of the PSMs using z-scan fluorescence correlation spectroscopy and fluorescence recovery after photobleaching experiments in combination with finite element simulations. Employing atomic force indentation experiments, we also investigated the mechanical properties of the PSMs. Both lipid diffusion constants and lateral membrane tension were compared to those obtained on PSMs derived from electroformed GUVs, which are known to be solvent- and detergent-free, under otherwise identical conditions. Our results demonstrate that the lipid diffusion, as well as the mechanical properties of the resulting PSMs, is almost unaffected by the GUV formation procedure but depends on the chosen substrate functionalization. With the new method in hand, we were able to reconstitute the syntaxin-1A transmembrane domain in microfluidic GUVs and PSMs, which was visualized by fluorescence microscopy.
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Affiliation(s)
- Kristina Kramer
- Institute of Organic and Biomolecular Chemistry, University of Göttingen, Tammannstrasse 2, 37077Göttingen, Germany
| | - Merve Sari
- Institute of Organic and Biomolecular Chemistry, University of Göttingen, Tammannstrasse 2, 37077Göttingen, Germany
| | - Kathrin Schulze
- Institute of Organic and Biomolecular Chemistry, University of Göttingen, Tammannstrasse 2, 37077Göttingen, Germany
| | - Hendrik Flegel
- Institute of Organic and Biomolecular Chemistry, University of Göttingen, Tammannstrasse 2, 37077Göttingen, Germany
| | - Miriam Stehr
- Institute of Organic and Biomolecular Chemistry, University of Göttingen, Tammannstrasse 2, 37077Göttingen, Germany
| | - Ingo Mey
- Institute of Organic and Biomolecular Chemistry, University of Göttingen, Tammannstrasse 2, 37077Göttingen, Germany
| | - Andreas Janshoff
- Institute of Physical Chemistry, University of Göttingen, Tammannstrasse 6, 37077Göttingen, Germany
| | - Claudia Steinem
- Institute of Organic and Biomolecular Chemistry, University of Göttingen, Tammannstrasse 2, 37077Göttingen, Germany.,Max Planck Institute for Dynamics and Self-Organization, Am Fassberg 17, 37077Göttingen, Germany
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11
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Ragaller F, Andronico L, Sykora J, Kulig W, Rog T, Urem YB, Abhinav, Danylchuk DI, Hof M, Klymchenko A, Amaro M, Vattulainen I, Sezgin E. Dissecting the mechanisms of environment sensitivity of smart probes for quantitative assessment of membrane properties. Open Biol 2022; 12:220175. [PMID: 36099931 PMCID: PMC9470265 DOI: 10.1098/rsob.220175] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
The plasma membrane, as a highly complex cell organelle, serves as a crucial platform for a multitude of cellular processes. Its collective biophysical properties are largely determined by the structural diversity of the different lipid species it accommodates. Therefore, a detailed investigation of biophysical properties of the plasma membrane is of utmost importance for a comprehensive understanding of biological processes occurring therein. During the past two decades, several environment-sensitive probes have been developed and become popular tools to investigate membrane properties. Although these probes are assumed to report on membrane order in similar ways, their individual mechanisms remain to be elucidated. In this study, using model membrane systems, we characterized the probes Pro12A, NR12S and NR12A in depth and examined their sensitivity to parameters with potential biological implications, such as the degree of lipid saturation, double bond position and configuration (cis versus trans), phospholipid headgroup and cholesterol content. Applying spectral imaging together with atomistic molecular dynamics simulations and time-dependent fluorescent shift analyses, we unravelled individual sensitivities of these probes to different biophysical properties, their distinct localizations and specific relaxation processes in membranes. Overall, Pro12A, NR12S and NR12A serve together as a toolbox with a wide range of applications allowing to select the most appropriate probe for each specific research question.
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Affiliation(s)
- Franziska Ragaller
- Science for Life Laboratory, Department of Women's and Children's Health, Karolinska Institutet, 17165 Solna, Sweden
| | - Luca Andronico
- Science for Life Laboratory, Department of Women's and Children's Health, Karolinska Institutet, 17165 Solna, Sweden
| | - Jan Sykora
- J. Heyrovský Institute of Physical Chemistry, Czech Academy of Sciences, Dolejškova 3, 18223 Prague 8, Czech Republic
| | - Waldemar Kulig
- Department of Physics, University of Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
| | - Tomasz Rog
- Department of Physics, University of Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
| | - Yagmur Balim Urem
- Science for Life Laboratory, Department of Women's and Children's Health, Karolinska Institutet, 17165 Solna, Sweden
| | - Abhinav
- J. Heyrovský Institute of Physical Chemistry, Czech Academy of Sciences, Dolejškova 3, 18223 Prague 8, Czech Republic
| | - Dmytro I Danylchuk
- Laboratoire de Bioimagerie et Pathologies, UMR 7021 CNRS, Université de Strasbourg, 74 Route du Rhin, 67401 Illkirch, France
| | - Martin Hof
- J. Heyrovský Institute of Physical Chemistry, Czech Academy of Sciences, Dolejškova 3, 18223 Prague 8, Czech Republic
| | - Andrey Klymchenko
- Laboratoire de Bioimagerie et Pathologies, UMR 7021 CNRS, Université de Strasbourg, 74 Route du Rhin, 67401 Illkirch, France
| | - Mariana Amaro
- J. Heyrovský Institute of Physical Chemistry, Czech Academy of Sciences, Dolejškova 3, 18223 Prague 8, Czech Republic
| | - Ilpo Vattulainen
- Department of Physics, University of Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
| | - Erdinc Sezgin
- Science for Life Laboratory, Department of Women's and Children's Health, Karolinska Institutet, 17165 Solna, Sweden
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12
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Bonet NF, Cava DG, Vélez M. Quartz crystal microbalance and atomic force microscopy to characterize mimetic systems based on supported lipids bilayer. Front Mol Biosci 2022; 9:935376. [PMID: 35992275 PMCID: PMC9382308 DOI: 10.3389/fmolb.2022.935376] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Accepted: 07/05/2022] [Indexed: 11/23/2022] Open
Abstract
Quartz Crystal Microbalance (QCM) with dissipation and Atomic Force Microscopy (AFM) are two characterization techniques that allow describing processes taking place at solid-liquid interfaces. Both are label-free and, when used in combination, provide kinetic, thermodynamic and structural information at the nanometer scale of events taking place at surfaces. Here we describe the basic operation principles of both techniques, addressing a non-specialized audience, and provide some examples of their use for describing biological events taking place at supported lipid bilayers (SLBs). The aim is to illustrate current strengths and limitations of the techniques and to show their potential as biophysical characterization techniques.
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13
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Gille B, Galuska CE, Fuchs B, Peleg S. Recent Advances in Studying Age-Associated Lipids Alterations and Dietary Interventions in Mammals. FRONTIERS IN AGING 2022; 2:773795. [PMID: 35822042 PMCID: PMC9261446 DOI: 10.3389/fragi.2021.773795] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Accepted: 10/28/2021] [Indexed: 11/16/2022]
Abstract
Lipids are involved in a broad spectrum of canonical biological functions, from energy supply and storage by triacylglycerols to membrane formation by sphingolipids, phospholipids and glycolipids. Because of this wide range of functions, there is an overlap between age-associated processes and lipid pathways. Lipidome analysis revealed age-related changes in the lipid composition of various tissues in mice and humans, which were also influenced by diet and gender. Some changes in the lipid profile can be linked to the onset of age-related neurodegenerative diseases like Alzheimer’s disease. Furthermore, the excessive accumulation of lipid storage organelles, lipid droplets, has significant implications for the development of inflammaging and non-communicable age-related diseases. Dietary interventions such as caloric restriction, time-restrictive eating, and lipid supplementation have been shown to improve pertinent health metrics or even extend life span and thus modulate aging processes.
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Affiliation(s)
- Benedikt Gille
- Research Group Epigenetics, Metabolism and Longevity, Research Institute for Farm Animal Biology (FBN), Dummerstorf, Germany
| | - Christina E Galuska
- Core Facility Metabolomics, Research Institute for Farm Animal Biology (FBN), Dummerstorf, Germany
| | - Beate Fuchs
- Core Facility Metabolomics, Research Institute for Farm Animal Biology (FBN), Dummerstorf, Germany
| | - Shahaf Peleg
- Research Group Epigenetics, Metabolism and Longevity, Research Institute for Farm Animal Biology (FBN), Dummerstorf, Germany.,Institute of Neuroregeneration and Neurorehabilitation, Qingdao University, Qingdao, China
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14
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Céspedes PF, Jainarayanan A, Fernández-Messina L, Valvo S, Saliba DG, Kurz E, Kvalvaag A, Chen L, Ganskow C, Colin-York H, Fritzsche M, Peng Y, Dong T, Johnson E, Siller-Farfán JA, Dushek O, Sezgin E, Peacock B, Law A, Aubert D, Engledow S, Attar M, Hester S, Fischer R, Sánchez-Madrid F, Dustin ML. T-cell trans-synaptic vesicles are distinct and carry greater effector content than constitutive extracellular vesicles. Nat Commun 2022; 13:3460. [PMID: 35710644 PMCID: PMC9203538 DOI: 10.1038/s41467-022-31160-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Accepted: 06/07/2022] [Indexed: 12/19/2022] Open
Abstract
The immunological synapse is a molecular hub that facilitates the delivery of three activation signals, namely antigen, costimulation/corepression and cytokines, from antigen-presenting cells (APC) to T cells. T cells release a fourth class of signaling entities, trans-synaptic vesicles (tSV), to mediate bidirectional communication. Here we present bead-supported lipid bilayers (BSLB) as versatile synthetic APCs to capture, characterize and advance the understanding of tSV biogenesis. Specifically, the integration of juxtacrine signals, such as CD40 and antigen, results in the adaptive tailoring and release of tSV, which differ in size, yields and immune receptor cargo compared with steadily released extracellular vesicles (EVs). Focusing on CD40L+ tSV as model effectors, we show that PD-L1 trans-presentation together with TSG101, ADAM10 and CD81 are key in determining CD40L vesicular release. Lastly, we find greater RNA-binding protein and microRNA content in tSV compared with EVs, supporting the specialized role of tSV as intercellular messengers.
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Affiliation(s)
- Pablo F Céspedes
- Kennedy Institute of Rheumatology, Nuffield Department of Orthopedics, Rheumatology and Musculoskeletal Sciences, The University of Oxford, Oxford, UK.
| | - Ashwin Jainarayanan
- Kennedy Institute of Rheumatology, Nuffield Department of Orthopedics, Rheumatology and Musculoskeletal Sciences, The University of Oxford, Oxford, UK
| | - Lola Fernández-Messina
- Immunology Service, Hospital de la Princesa, Instituto Investigación Sanitaria Princesa, Universidad Autónoma de Madrid, Madrid, Spain
- Intercellular communication in the inflammatory response. Vascular Physiology Area, Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain
| | - Salvatore Valvo
- Kennedy Institute of Rheumatology, Nuffield Department of Orthopedics, Rheumatology and Musculoskeletal Sciences, The University of Oxford, Oxford, UK
| | - David G Saliba
- Kennedy Institute of Rheumatology, Nuffield Department of Orthopedics, Rheumatology and Musculoskeletal Sciences, The University of Oxford, Oxford, UK
| | - Elke Kurz
- Kennedy Institute of Rheumatology, Nuffield Department of Orthopedics, Rheumatology and Musculoskeletal Sciences, The University of Oxford, Oxford, UK
| | - Audun Kvalvaag
- Kennedy Institute of Rheumatology, Nuffield Department of Orthopedics, Rheumatology and Musculoskeletal Sciences, The University of Oxford, Oxford, UK
| | - Lina Chen
- Kennedy Institute of Rheumatology, Nuffield Department of Orthopedics, Rheumatology and Musculoskeletal Sciences, The University of Oxford, Oxford, UK
| | - Charity Ganskow
- Kennedy Institute of Rheumatology, Nuffield Department of Orthopedics, Rheumatology and Musculoskeletal Sciences, The University of Oxford, Oxford, UK
| | - Huw Colin-York
- Kennedy Institute of Rheumatology, Nuffield Department of Orthopedics, Rheumatology and Musculoskeletal Sciences, The University of Oxford, Oxford, UK
- MRC Human Immunology Unit, MRC Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, The University of Oxford, Oxford, UK
| | - Marco Fritzsche
- Kennedy Institute of Rheumatology, Nuffield Department of Orthopedics, Rheumatology and Musculoskeletal Sciences, The University of Oxford, Oxford, UK
- MRC Human Immunology Unit, MRC Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, The University of Oxford, Oxford, UK
| | - Yanchun Peng
- MRC Human Immunology Unit, MRC Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, The University of Oxford, Oxford, UK
- Chinese Academy of Medical Science (CAMS) Oxford Institute (COI), University of Oxford, Oxford, UK
| | - Tao Dong
- MRC Human Immunology Unit, MRC Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, The University of Oxford, Oxford, UK
- Chinese Academy of Medical Science (CAMS) Oxford Institute (COI), University of Oxford, Oxford, UK
| | - Errin Johnson
- Sir William Dunn School of Pathology, The University of Oxford, Oxford, UK
| | | | - Omer Dushek
- Sir William Dunn School of Pathology, The University of Oxford, Oxford, UK
| | - Erdinc Sezgin
- Science for Life Laboratory, Department of Women's and Children's Health, Karolinska Institutet, Stockholm, Sweden
| | | | | | | | - Simon Engledow
- Oxford Genomics Centre, Wellcome Centre for Human Genetics, The University of Oxford, Oxford, UK
| | - Moustafa Attar
- Kennedy Institute of Rheumatology, Nuffield Department of Orthopedics, Rheumatology and Musculoskeletal Sciences, The University of Oxford, Oxford, UK
- Oxford Genomics Centre, Wellcome Centre for Human Genetics, The University of Oxford, Oxford, UK
| | - Svenja Hester
- Target Discovery Institute, Centre for Medicines Discovery, Nuffield Department of Medicine, The University of Oxford, Oxford, UK
| | - Roman Fischer
- Target Discovery Institute, Centre for Medicines Discovery, Nuffield Department of Medicine, The University of Oxford, Oxford, UK
| | - Francisco Sánchez-Madrid
- Immunology Service, Hospital de la Princesa, Instituto Investigación Sanitaria Princesa, Universidad Autónoma de Madrid, Madrid, Spain
- Intercellular communication in the inflammatory response. Vascular Physiology Area, Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain
| | - Michael L Dustin
- Kennedy Institute of Rheumatology, Nuffield Department of Orthopedics, Rheumatology and Musculoskeletal Sciences, The University of Oxford, Oxford, UK.
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15
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Dam T, Chouliara M, Junghans V, Jönsson P. Supported Lipid Bilayers and the Study of Two-Dimensional Binding Kinetics. Front Mol Biosci 2022; 9:833123. [PMID: 35252352 PMCID: PMC8896763 DOI: 10.3389/fmolb.2022.833123] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Accepted: 01/27/2022] [Indexed: 11/13/2022] Open
Abstract
Binding between protein molecules on contacting cells is essential in initiating and regulating several key biological processes. In contrast to interactions between molecules in solution, these events are restricted to the two-dimensional (2D) plane of the meeting cell surfaces. However, converting between the more commonly available binding kinetics measured in solution and the so-called 2D binding kinetics has proven a complicated task since for the latter several factors other than the protein-protein interaction per se have an impact. A few important examples of these are: protein density, membrane fluctuations, force on the bond and the use of auxiliary binding molecules. The development of model membranes, and in particular supported lipid bilayers (SLBs), has made it possible to simplify the studied contact to analyze these effects and to measure 2D binding kinetics of individual protein-protein interactions. We will in this review give an overview of, and discuss, how different SLB systems have been used for this and compare different methods to measure binding kinetics in cell-SLB contacts. Typically, the SLB is functionalized with fluorescently labelled ligands whose interaction with the corresponding receptor on a binding cell can be detected. This interaction can either be studied 1) by an accumulation of ligands in the cell-SLB contact, whose magnitude depends on the density of the proteins and binding affinity of the interaction, or 2) by tracking single ligands in the SLB, which upon interaction with a receptor result in a change of motion of the diffusing ligand. The advantages and disadvantages of other methods measuring 2D binding kinetics will also be discussed and compared to the fluorescence-based methods. Although binding kinetic measurements in cell-SLB contacts have provided novel information on how ligands interact with receptors in vivo the number of these measurements is still limited. This is influenced by the complexity of the system as well as the required experimental time. Moreover, the outcome can vary significantly between studies, highlighting the necessity for continued development of methods to study 2D binding kinetics with higher precision and ease.
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Affiliation(s)
- Tommy Dam
- Department of Chemistry, Lund University, Lund, Sweden
| | | | - Victoria Junghans
- Nuffield Department of Medicine, CAMS Oxford Institute, University of Oxford, Oxford, United Kingdom
| | - Peter Jönsson
- Department of Chemistry, Lund University, Lund, Sweden
- *Correspondence: Peter Jönsson,
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16
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Sych T, Levental KR, Sezgin E. Lipid–Protein Interactions in Plasma Membrane Organization and Function. Annu Rev Biophys 2022; 51:135-156. [DOI: 10.1146/annurev-biophys-090721-072718] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Lipid–protein interactions in cells are involved in various biological processes, including metabolism, trafficking, signaling, host–pathogen interactions, and transmembrane transport. At the plasma membrane, lipid–protein interactions play major roles in membrane organization and function. Several membrane proteins have motifs for specific lipid binding, which modulate protein conformation and consequent function. In addition to such specific lipid–protein interactions, protein function can be regulated by the dynamic, collective behavior of lipids in membranes. Emerging analytical, biochemical, and computational technologies allow us to study the influence of specific lipid–protein interactions, as well as the collective behavior of membranes on protein function. In this article, we review the recent literature on lipid–protein interactions with a specific focus on the current state-of-the-art technologies that enable novel insights into these interactions. Expected final online publication date for the Annual Review of Biophysics, Volume 51 is May 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- Taras Sych
- Science for Life Laboratory, Department of Women's and Children's Health, Karolinska Institutet, Solna, Sweden;,
| | - Kandice R. Levental
- Department of Molecular Physiology and Biological Physics, Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, Virginia, USA
| | - Erdinc Sezgin
- Science for Life Laboratory, Department of Women's and Children's Health, Karolinska Institutet, Solna, Sweden;,
- MRC Human Immunology Unit, MRC Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, United Kingdom
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17
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Trapping or slowing the diffusion of T cell receptors at close contacts initiates T cell signaling. Proc Natl Acad Sci U S A 2021; 118:2024250118. [PMID: 34526387 PMCID: PMC8488633 DOI: 10.1073/pnas.2024250118] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/05/2021] [Indexed: 12/27/2022] Open
Abstract
T cell activation is initiated by T cell receptor (TCR) phosphorylation. This requires the local depletion of large receptor-type phosphatases from "close contacts" formed when T cells interact with surfaces presenting agonistic TCR ligands, but exactly how the ligands potentiate signaling is unclear. It has been proposed that TCR ligands could enhance receptor phosphorylation and signaling just by holding TCRs in phosphatase-depleted close contacts, but this has not been directly tested. We devised simple methods to move the TCR in and out of close contacts formed by T cells interacting with supported lipid bilayers (SLBs) and to slow the receptor's diffusion in the contacts, using a series of anti-CD3ε Fab- and ligand-based adducts of the receptor. TCRs engaging a Fab extended with the large extracellular region of CD45 were excluded from contacts and produced no signaling. Conversely, allowing the extended Fab to become tethered to the SLB trapped the TCR in the close contacts, leading to very strong signaling. Importantly, attaching untethered anti-CD3ε Fab or peptide/MHC ligands, each of which were largely inactive in solution but both of which reduced TCR diffusion in close contacts approximately fivefold, also initiated signaling during cell/SLB contact. Our findings indicate that holding TCRs in close contacts or simply slowing their diffusion in phosphatase-depleted regions of the cell surface suffices to initiate signaling, effects we could reproduce in single-particle stochastic simulations. Our study shows that the TCR is preconfigured for signaling in a way that allows it to be triggered by ligands acting simply as receptor "traps."
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18
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Chattopadhyay M, Krok E, Orlikowska H, Schwille P, Franquelim HG, Piatkowski L. Hydration Layer of Only a Few Molecules Controls Lipid Mobility in Biomimetic Membranes. J Am Chem Soc 2021; 143:14551-14562. [PMID: 34342967 PMCID: PMC8447254 DOI: 10.1021/jacs.1c04314] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
![]()
Self-assembly of
biomembranes results from the intricate interactions
between water and the lipids’ hydrophilic head groups. Therefore,
the lipid–water interplay strongly contributes to modulating
membrane architecture, lipid diffusion, and chemical activity. Here,
we introduce a new method of obtaining dehydrated, phase-separated,
supported lipid bilayers (SLBs) solely by controlling the decrease
of their environment’s relative humidity. This facilitates
the study of the structure and dynamics of SLBs over a wide range
of hydration states. We show that the lipid domain structure of phase-separated
SLBs is largely insensitive to the presence of the hydration layer.
In stark contrast, lipid mobility is drastically affected by dehydration,
showing a 6-fold decrease in lateral diffusion. At the same time,
the diffusion activation energy increases approximately 2-fold for
the dehydrated membrane. The obtained results, correlated with the
hydration structure of a lipid molecule, revealed that about six to
seven water molecules directly hydrating the phosphocholine moiety
play a pivotal role in modulating lipid diffusion. These findings
could provide deeper insights into the fundamental reactions where
local dehydration occurs, for instance during cell–cell fusion,
and help us better understand the survivability of anhydrobiotic organisms.
Finally, the strong dependence of lipid mobility on the number of
hydrating water molecules opens up an application potential for SLBs
as very precise, nanoscale hydration sensors.
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Affiliation(s)
- Madhurima Chattopadhyay
- Faculty of Materials Engineering and Technical Physics, Poznan University of Technology, Piotrowo 3, 60-965 Poznan, Poland
| | - Emilia Krok
- Faculty of Materials Engineering and Technical Physics, Poznan University of Technology, Piotrowo 3, 60-965 Poznan, Poland
| | - Hanna Orlikowska
- Faculty of Materials Engineering and Technical Physics, Poznan University of Technology, Piotrowo 3, 60-965 Poznan, Poland
| | - Petra Schwille
- Department of Cellular and Molecular Biophysics, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany
| | - Henri G Franquelim
- Department of Cellular and Molecular Biophysics, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany
| | - Lukasz Piatkowski
- Faculty of Materials Engineering and Technical Physics, Poznan University of Technology, Piotrowo 3, 60-965 Poznan, Poland
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19
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Sych T, Gurdap CO, Wedemann L, Sezgin E. How Does Liquid-Liquid Phase Separation in Model Membranes Reflect Cell Membrane Heterogeneity? MEMBRANES 2021; 11:323. [PMID: 33925240 PMCID: PMC8146956 DOI: 10.3390/membranes11050323] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Revised: 04/22/2021] [Accepted: 04/26/2021] [Indexed: 11/22/2022]
Abstract
Although liquid-liquid phase separation of cytoplasmic or nuclear components in cells has been a major focus in cell biology, it is only recently that the principle of phase separation has been a long-standing concept and extensively studied in biomembranes. Membrane phase separation has been reconstituted in simplified model systems, and its detailed physicochemical principles, including essential phase diagrams, have been extensively explored. These model membrane systems have proven very useful to study the heterogeneity in cellular membranes, however, concerns have been raised about how reliably they can represent native membranes. In this review, we will discuss how phase-separated membrane systems can mimic cellular membranes and where they fail to reflect the native cell membrane heterogeneity. We also include a few humble suggestions on which phase-separated systems should be used for certain applications, and which interpretations should be avoided to prevent unreliable conclusions.
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Affiliation(s)
| | | | | | - Erdinc Sezgin
- Science for Life Laboratory, Department of Women’s and Children’s Health, Karolinska Institutet, 17165 Solna, Sweden; (T.S.); (C.O.G.); (L.W.)
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