Membranes

Editorial

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3 pages, 204 KiB

Open AccessEditorial

Special Issue: Dynamics and Nano-Organization in Plasma Membranes

by Yenisleidy de las Mercedes Zulueta Díaz and Eva Christensen Arnspang

Membranes 2021, 11(11), 828; https://doi.org/10.3390/membranes11110828 - 27 Oct 2021

Cited by 2 | Viewed by 1511

Abstract

Cell membranes develop extraordinarily complex lipids and proteins geared to perform functions required by cells [...] Full article

(This article belongs to the Special Issue Dynamics and Nano-Organization in Plasma Membranes)

Research

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12 pages, 768 KiB

Open AccessCommunication

Molecular Diffusion of ABCA1 at the Cell Surface of Living Cells Assessed by svFCS

by Olga Raducka-Jaszul, Karolina Wójtowicz, Aleksander F. Sikorski, Giovanna Chimini, Yannick Hamon and Tomasz Trombik

Membranes 2021, 11(7), 498; https://doi.org/10.3390/membranes11070498 - 30 Jun 2021

Cited by 6 | Viewed by 2807

Abstract

Extensive studies showed the crucial role of ATP binding cassette (ABC) transporter ABCA1 in organizing the lipid microenvironment at the plasma membrane (PM) of living cells. However, the exact role of this protein in terms of lipid redistribution and lateral reorganization of the [...] Read more.

Extensive studies showed the crucial role of ATP binding cassette (ABC) transporter ABCA1 in organizing the lipid microenvironment at the plasma membrane (PM) of living cells. However, the exact role of this protein in terms of lipid redistribution and lateral reorganization of the PM is still being discussed. Here, we took advantage of the spot variation fluorescence correlation spectroscopy (svFCS) to investigate the molecular dynamics of the ABCA1 expressed at the PM of Chinese hamster ovary cells (CHO-K1). We confirmed that this protein is strongly confined into the raft nanodomains. Next, in agreement with our previous observations, we showed that amphotericin B does not affect the diffusion properties of an active ABCA1 in contrary to inactive mutant ABCA1MM. We also evidenced that ApoA1 influences the molecular diffusion properties of ABCA1. Finally, we showed that the molecular confinement of ABCA1 depends on the cholesterol content in the PM, but presumably, this is not the only factor responsible for that. We concluded that the molecular dynamics of ABCA1 strongly depends on its activity and the PM composition. We hypothesize that other factors than lipids (i.e., proteins) are responsible for the strong confinement of ABCA1 in PM nanodomains which possibility has to be elucidated. Full article

(This article belongs to the Special Issue Dynamics and Nano-Organization in Plasma Membranes)

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7 pages, 984 KiB

Open AccessArticle

Defining the Diffusion in Model Membranes Using Line Fluorescence Recovery after Photobleaching

by Jakob L. Kure, Camilla B. Andersen, Thomas E. Rasmussen, B. Christoffer Lagerholm and Eva C. Arnspang

Membranes 2020, 10(12), 434; https://doi.org/10.3390/membranes10120434 - 17 Dec 2020

Cited by 9 | Viewed by 3234

Abstract

In this study, we explore the use of line FRAP to detect diffusion in synthetic lipid membranes. The study of the dynamics of these membrane lipids can, however, be challenging. The diffusion in two different synthetic membranes consisting of the lipid mixtures 1:1 [...] Read more.

In this study, we explore the use of line FRAP to detect diffusion in synthetic lipid membranes. The study of the dynamics of these membrane lipids can, however, be challenging. The diffusion in two different synthetic membranes consisting of the lipid mixtures 1:1 DOPC:DPPC and 2:2:1 DOPC:DPPC:Cholesterol was studied with line FRAP. A correlation between diffusion coefficient and temperature was found to be dependent on the morphology of the membrane. We suggest line FRAP as a promising accessible and simple technique to study diffusion in plasma membranes. Full article

(This article belongs to the Special Issue Dynamics and Nano-Organization in Plasma Membranes)

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13 pages, 792 KiB

Open AccessArticle

Recent Experiments Support a Microemulsion Origin of Plasma Membrane Domains: Dependence of Domain Size on Physical Parameters

by David W. Allender and M. Schick

Membranes 2020, 10(8), 167; https://doi.org/10.3390/membranes10080167 - 28 Jul 2020

Cited by 7 | Viewed by 3058

Abstract

It is widely, but not universally, believed that the lipids of the plasma membrane are not uniformly distributed, but that “rafts” of sphingolipids and cholesterol float in a “sea” of unsaturated lipids. The physical origin of such heterogeneities is often attributed to a [...] Read more.

It is widely, but not universally, believed that the lipids of the plasma membrane are not uniformly distributed, but that “rafts” of sphingolipids and cholesterol float in a “sea” of unsaturated lipids. The physical origin of such heterogeneities is often attributed to a phase coexistence between the two different domains. We argue that this explanation is untenable for several reasons. Further, we note that the results of recent experiments are inconsistent with this picture. However, they are quite consistent with an alternate explanation, namely, that the plasma membrane is a microemulsion of the two kinds of regions. To show this, we briefly review a simplified version of this theory and its phase diagram. We also explicate the dependence of the predicted domain size on four physical parameters. They are the energy cost of gradients in the composition, the spontaneous curvature of the membrane, its bending modulus and its surface tension. Taking values of the latter two from experiment, we obtain domain sizes for several different cell types that vary from 58 to 88 nm. Full article

(This article belongs to the Special Issue Dynamics and Nano-Organization in Plasma Membranes)

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18 pages, 5520 KiB

Open AccessArticle

Effect of Vitamin K₃ Inhibiting the Function of NorA Efflux Pump and Its Gene Expression on Staphylococcus aureus

by Saulo R. Tintino, Veruska C. A. de Souza, Julia M. A. da Silva, Cícera Datiane de M. Oliveira-Tintino, Pedro S. Pereira, Tereza C. Leal-Balbino, Antonio Pereira-Neves, José P. Siqueira-Junior, José G. M. da Costa, Fabíola F. G. Rodrigues, Irwin R. A. Menezes, Gabriel C. A. da Hora, Maria C. P. Lima, Henrique D. M. Coutinho and Valdir Q. Balbino

Membranes 2020, 10(6), 130; https://doi.org/10.3390/membranes10060130 - 25 Jun 2020

Cited by 38 | Viewed by 4444

Abstract

Resistance to antibiotics has made diseases that previously healed easily become more difficult to treat. Staphylococcus aureus is an important cause of hospital-acquired infections and multi-drug resistant. NorA efflux pump, present in bacteria S. aureus, is synthesized by the expression of the [...] Read more.

Resistance to antibiotics has made diseases that previously healed easily become more difficult to treat. Staphylococcus aureus is an important cause of hospital-acquired infections and multi-drug resistant. NorA efflux pump, present in bacteria S. aureus, is synthesized by the expression of the norA gene. Menadione, also known as vitamin K₃, is one of the synthetic forms of vitamin K. Therefore, the aim of this study is to verify the menadione effect on efflux inhibition through NorA pump gene expression inhibition and assess the effects of menadione in bacterial membrane. The effect of menadione as an efflux pump inhibitor (EPI) was evaluated by the microdilution method, fluorimetry, electron microscopy, and by RT-qPCR to evaluate gene expression. In the molecular docking, association with menadione induces increased fluorescence intensity. Menadione was observed (100% of the clusters) interacting with residues ILE12, ILE15, PHE16, ILE19, PHE47, GLN51, ALA105, and MET109 from NorA. The results showed the norA gene had its expression significantly diminished in the presence of menadione. The simulation showed that several menadione molecules were able to go through the bilayer and allow the entry of water molecules into the hydrophobic regions of the bilayer. When present within membranes, menadione may have caused membrane structural changes resulting in a decline of the signaling pathways involved in norA expression. Menadione demonstrated to be an efflux pump inhibitor with dual mechanism: affecting the efflux pump by direct interaction with protein NorA and indirectly inhibiting the norA gene expression, possibly by affecting regulators present in the membrane altered by menadione. Full article

(This article belongs to the Special Issue Dynamics and Nano-Organization in Plasma Membranes)

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Review

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15 pages, 785 KiB

Open AccessEditor’s ChoiceReview

The Nanoscopic Organization of Synapse Structures: A Common Basis for Cell Communication

by Xiaojuan Yang and Wim Annaert

Membranes 2021, 11(4), 248; https://doi.org/10.3390/membranes11040248 - 30 Mar 2021

Cited by 14 | Viewed by 6189

Abstract

Synapse structures, including neuronal and immunological synapses, can be seen as the plasma membrane contact sites between two individual cells where information is transmitted from one cell to the other. The distance between the two plasma membranes is only a few tens of [...] Read more.

Synapse structures, including neuronal and immunological synapses, can be seen as the plasma membrane contact sites between two individual cells where information is transmitted from one cell to the other. The distance between the two plasma membranes is only a few tens of nanometers, but these areas are densely populated with functionally different proteins, including adhesion proteins, receptors, and transporters. The narrow space between the two plasma membranes has been a barrier for resolving the synaptic architecture due to the diffraction limit in conventional microscopy (~250 nm). Various advanced super-resolution microscopy techniques, such as stimulated emission depletion (STED), structured illumination microscopy (SIM), and single-molecule localization microscopy (SMLM), bypass the diffraction limit and provide a sub-diffraction-limit resolving power, ranging from 10 to 100 nm. The studies using super-resolution microscopy have revealed unprecedented details of the nanoscopic organization and dynamics of synaptic molecules. In general, most synaptic proteins appear to be heterogeneously distributed and form nanodomains at the membranes. These nanodomains are dynamic functional units, playing important roles in mediating signal transmission through synapses. Herein, we discuss our current knowledge on the super-resolution nanoscopic architecture of synapses and their functional implications, with a particular focus on the neuronal synapses and immune synapses. Full article

(This article belongs to the Special Issue Dynamics and Nano-Organization in Plasma Membranes)

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15 pages, 1595 KiB

Open AccessFeature PaperReview

Revealing Plasma Membrane Nano-Domains with Diffusion Analysis Methods

by Jakob L. Kure, Camilla B. Andersen, Kim I. Mortensen, Paul W. Wiseman and Eva C. Arnspang

Membranes 2020, 10(11), 314; https://doi.org/10.3390/membranes10110314 - 29 Oct 2020

Cited by 18 | Viewed by 4042

Abstract

Nano-domains are sub-light-diffraction-sized heterogeneous areas in the plasma membrane of cells, which are involved in cell signalling and membrane trafficking. Throughout the last thirty years, these nano-domains have been researched extensively and have been the subject of multiple theories and models: the lipid [...] Read more.

Nano-domains are sub-light-diffraction-sized heterogeneous areas in the plasma membrane of cells, which are involved in cell signalling and membrane trafficking. Throughout the last thirty years, these nano-domains have been researched extensively and have been the subject of multiple theories and models: the lipid raft theory, the fence model, and the protein oligomerization theory. Strong evidence exists for all of these, and consequently they were combined into a hierarchal model. Measurements of protein and lipid diffusion coefficients and patterns have been instrumental in plasma membrane research and by extension in nano-domain research. This has led to the development of multiple methodologies that can measure diffusion and confinement parameters including single particle tracking, fluorescence correlation spectroscopy, image correlation spectroscopy and fluorescence recovery after photobleaching. Here we review the performance and strengths of these methods in the context of their use in identification and characterization of plasma membrane nano-domains. Full article

(This article belongs to the Special Issue Dynamics and Nano-Organization in Plasma Membranes)

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Other

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6 pages, 880 KiB

Open AccessBrief Report

Using kICS to Reveal Changed Membrane Diffusion of AQP-9 Treated with Drugs

by Jakob L. Kure, Thommie Karlsson, Camilla B. Andersen, B. Christoffer Lagerholm, Vesa Loitto, Karl-Eric Magnusson and Eva C. Arnspang

Membranes 2021, 11(8), 568; https://doi.org/10.3390/membranes11080568 - 28 Jul 2021

Cited by 3 | Viewed by 2233

Abstract

The formation of nanodomains in the plasma membrane are thought to be part of membrane proteins regulation and signaling. Plasma membrane proteins are often investigated by analyzing the lateral mobility. k-space ICS (kICS) is a powerful image correlation spectroscopy (ICS) technique and a [...] Read more.

The formation of nanodomains in the plasma membrane are thought to be part of membrane proteins regulation and signaling. Plasma membrane proteins are often investigated by analyzing the lateral mobility. k-space ICS (kICS) is a powerful image correlation spectroscopy (ICS) technique and a valuable supplement to fluorescence correlation spectroscopy (FCS). Here, we study the diffusion of aquaporin-9 (AQP9) in the plasma membrane, and the effect of different membrane and cytoskeleton affecting drugs, and therefore nanodomain perturbing, using kICS. We measured the diffusion coefficient of AQP9 after addition of these drugs using live cell Total Internal Reflection Fluorescence imaging on HEK-293 cells. The actin polymerization inhibitors Cytochalasin D and Latrunculin A do not affect the diffusion coefficient of AQP9. Methyl-β-Cyclodextrin decreases GFP-AQP9 diffusion coefficient in the plasma membrane. Human epidermal growth factor led to an increase in the diffusion coefficient of AQP9. These findings led to the conclusion that kICS can be used to measure diffusion AQP9, and suggests that the AQP9 is not part of nanodomains. Full article

(This article belongs to the Special Issue Dynamics and Nano-Organization in Plasma Membranes)

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9 pages, 1633 KiB

Open AccessBrief Report

Creating Supported Plasma Membrane Bilayers Using Acoustic Pressure

by Erdinc Sezgin, Dario Carugo, Ilya Levental, Eleanor Stride and Christian Eggeling

Membranes 2020, 10(2), 30; https://doi.org/10.3390/membranes10020030 - 18 Feb 2020

Cited by 8 | Viewed by 5195

Abstract

Model membrane systems are essential tools for the study of biological processes in a simplified setting to reveal the underlying physicochemical principles. As cell-derived membrane systems, giant plasma membrane vesicles (GPMVs) constitute an intermediate model between live cells and fully artificial structures. Certain [...] Read more.

Model membrane systems are essential tools for the study of biological processes in a simplified setting to reveal the underlying physicochemical principles. As cell-derived membrane systems, giant plasma membrane vesicles (GPMVs) constitute an intermediate model between live cells and fully artificial structures. Certain applications, however, require planar membrane surfaces. Here, we report a new approach for creating supported plasma membrane bilayers (SPMBs) by bursting cell-derived GPMVs using ultrasound within a microfluidic device. We show that the mobility of outer leaflet molecules is preserved in SPMBs, suggesting that they are accessible on the surface of the bilayers. Such model membrane systems are potentially useful in many applications requiring detailed characterization of plasma membrane dynamics. Full article

(This article belongs to the Special Issue Dynamics and Nano-Organization in Plasma Membranes)

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