scispace - formally typeset
Search or ask a question
Journal ArticleDOI

Dynamics in the plasma membrane: how to combine fluidity and order

TL;DR: The basic concepts of Brownian diffusion and lipid domain formation in model membranes are summarized and the development of ideas and tools in this field are tracked, outlining key results obtained on the dynamic processes at work in membrane structure and assembly.
Abstract: Cell membranes are fascinating supramolecular aggregates that not only form a barrier between compartments but also harbor many chemical reactions essential to the existence and functioning of a cell. Here, it is proposed to review the molecular dynamics and mosaic organization of the plasma membrane, which are thought to have important functional implications. We will first summarize the basic concepts of Brownian diffusion and lipid domain formation in model membranes and then track the development of ideas and tools in this field, outlining key results obtained on the dynamic processes at work in membrane structure and assembly. We will focus in particular on findings made using fluorescent labeling and imaging procedures to record these dynamic processes. We will also discuss a few examples showing the impact of lateral diffusion on cell signal transduction, and outline some future methodological challenges which must be met before we can answer some of the questions arising in this field of research.

Content maybe subject to copyright    Report

Citations
More filters
Dissertation
01 Jan 2008
TL;DR: The data indicate that membrane rafts might play a role in the compartmentalization of biological processes at the plasma membrane in response to biotic stimuli.
Abstract: In the last years, lateral compartmentalization has become a well-recognized topic in plant membrane research. Especially the membrane raft hypothesis receives particular attention, since it gives a conceivable explanation for the spatial and temporal organization of biological membranes. The aim of the work presented here was the investigation of the possible involvement of membrane rafts in biotic stress responses. In this study we elucidated in a quantitative proteomics approach immediate-early protein dynamics in plasma membrane-derived detergent-resistant membranes (DRMs) in response to bacterial flagellin. Proton ATPases and receptor-like kinases were the most prominently enriched protein classes. Strikingly, the flagellin receptor FLS2 was consistently relocalized to DMRs, indicative of its possible recruitment to membrane rafts prior to ligand-induced endocytosis. We performed reverse genetics and pharmacological interference to address the potential contribution of the identified proteins in flg22-triggered responses and thereby identified two novel players of elicitor-dependent oxidative burst control. In a second approach we aimed to elucidate the potential role of membrane rafts and/or sterols during the cellular compartmentalization process in the context of the Arabidopsis�powdery mildew interaction. We showed that the SNARE AtPEN1, which focally accumulates at fungal entry sites, partially associated with DRMs in a sterol-dependent manner. A complementary approach aiming at the genetic interference with membrane raft function revealed that a subset of sterol biosynthesis mutants displayed enhanced resistance towards the adapted powdery mildew pathogen, Golovinomyces orontii. This could be partially correlated with an aberrant focal accumulation of GFP-AtPEN1 underneath fungal attack sites, suggesting that the proper sterol composition, which might affect membrane raft integrity, could be important for the focal accumulation of GFP-AtPEN1 at attempted fungal entry sites. In sum our data indicate that membrane rafts might play a role in the compartmentalization of biological processes at the plasma membrane in response to biotic stimuli.

3 citations


Cites background from "Dynamics in the plasma membrane: ho..."

  • ...In this model it is assumed that the cortical actin cytoskeleton (so called fences) and transmembrane proteins anchored to it (so called pickets) restrict the lateral diffusion of transmembrane proteins (Marguet et al., 2006)....

    [...]

Dissertation
01 Jan 2012
TL;DR: The experimental data suggest that the localization of PKA I to lipid rafts is mediated by interaction with A-kinase anchoring proteins (AKAPs), and PKA signaling events were reversed when potential PKA type I interactions with AKAPs were disrupted with competitive peptides.
Abstract: Platelet activation is a critical physiological event, whose main role is to prevent excessive blood loss and repair vessel wall injuries. However, platelet activation must be controlled to prevent unwanted and exaggerated responses leading to the occlusion of the blood vessel. The endothelial-derived inhibitors prostacyclin (PGI2) and nitric oxide (NO) are known to play a critical role in the control of platelet activity, although the mechanism underlying their actions remains unclear beyond the triggering of cyclic nucleotides signaling pathways. The aim of this study was to improve our understanding of platelet regulation by cAMP signaling networks. We observed differences in cAMP signaling depending on the agonists used. Using phosphorylation of PKA substrates as a marker of PKA activity, it was observed that PKA substrates were phosphorylated and dephosphorylated at different time points in a unique temporal pattern. Consistent with this observation we found that individual PKA isoforms, PKA I and II, were localized in distinct subcellular compartments, with PKA I being identified as a lipid raft protein. Our experimental data suggest that the localization of PKA I to lipid rafts is mediated by interaction with A-kinase anchoring proteins (AKAPs). Additionally, PKA signaling events were reversed when potential PKA type I interactions with AKAPs were disrupted with competitive peptides. Using this approach we found that the redistribution of PKA I to lipid rafts facilitated the phosphorylation of GPIbβ and the inhibition of vonWillebrand factor-mediated aggregation. Our data also demonstrated for the first time that the chemical disruption of lipid rafts increased platelet sensitivity to PGI2, through increased cAMP production and

3 citations

Journal ArticleDOI
TL;DR: An unprecedented dynamic coupling between polymer chains and phospholipid bilayers at different length/time scales is suggested and the structural phase map and multiscale dynamics of the liposome–polymer mixtures are investigated.
Abstract: Understanding dynamic and complex interaction of biological membranes with extracellular matrices plays a crucial role in controlling a variety of cell behavior and functions, from cell adhesion and growth to signaling and differentiation. Tremendous interest in tissue engineering has made it possible to design polymeric scaffolds mimicking the topology and mechanical properties of the native extracellular microenvironment; however, a fundamental question remains unanswered: that is, how the viscoelastic extracellular environment modifies the hierarchical dynamics of lipid membranes. In this work, we used aqueous solutions of poly(ethylene glycol) (PEG) with different molecular weights to mimic the viscous medium of cells and nearly monodisperse unilamellar DMPC/DMPG liposomes as a membrane model. Using small-angle X-ray scattering (SAXS), dynamic light scattering, temperature-modulated differential scanning calorimetry, bulk rheology, and fluorescence lifetime spectroscopy, we investigated the structural phase map and multiscale dynamics of the liposome–polymer mixtures. The results suggest an unprecedented dynamic coupling between polymer chains and phospholipid bilayers at different length/time scales. The microviscosity of the lipid bilayers is directly influenced by the relaxation of the whole chain, resulting in accelerated dynamics of lipids within the bilayers in the case of short chains compared to the polymer-free liposome case. At the macroscopic level, the gel-to-fluid transition of the bilayers results in a remarkable thermal-stiffening behavior of polymer–liposome solutions that can be modified by the concentration of the liposomes and the polymer chain length.

3 citations

Journal ArticleDOI
TL;DR: In this article , the tetraspanin protein, TSP-15, is recruited to large membrane wounds and forms a ring-like structure in C. elegans epidermis.

3 citations

Journal ArticleDOI
TL;DR: In this paper, a planar nano-antenna platform combined with fluorescence correlation spectroscopy is introduced to study spatiotemporal heterogeneities on living cell membranes at the nano- up to the mesoscale.
Abstract: Dynamic compartmentalization is a prevailing principle regulating the spatiotemporal organization of the living cell membrane from the nano- up to the mesoscale. This non-arbitrary organization is intricately linked to cell function. On living cell membranes, dynamic domains or 'membrane rafts' enriched with cholesterol, sphingolipids and other certain proteins exist at the nanoscale serving as signaling and sorting platforms. Moreover, it has been postulated that other local organizers of the cell membrane such as intrinsic protein interactions, the extracellular matrix and/or the actin cytoskeleton synergize with rafts to provide spatiotemporal hierarchy to the membrane. Elucidating the intricate coupling of multiple spatial and temporal scales requires the application of correlative techniques, with a particular need for simultaneous nanometer spatial precision and microsecond temporal resolution. Here, we review novel fluorescence-based techniques that readily allow to decode nanoscale membrane dynamics with unprecedented spatiotemporal resolution and single-molecule sensitivity. We particularly focus on correlative approaches from the field of nanophotonics. Notably, we introduce a versatile planar nanoantenna platform combined with fluorescence correlation spectroscopy to study spatiotemporal heterogeneities on living cell membranes at the nano- up to the mesoscale. Finally, we outline remaining future technological challenges and comment on potential directions to advance our understanding of cell membrane dynamics under the influence of the actin cytoskeleton and extracellular matrix in uttermost detail.

3 citations

References
More filters
Journal ArticleDOI
18 Feb 1972-Science
TL;DR: Results strongly indicate that the bivalent antibodies produce an aggregation of the surface immunoglobulin molecules in the plane of the membrane, which can occur only if the immunoglOBulin molecules are free to diffuse in the membrane.
Abstract: A fluid mosaic model is presented for the gross organization and structure of the proteins and lipids of biological membranes. The model is consistent with the restrictions imposed by thermodynamics. In this model, the proteins that are integral to the membrane are a heterogeneous set of globular molecules, each arranged in an amphipathic structure, that is, with the ionic and highly polar groups protruding from the membrane into the aqueous phase, and the nonpolar groups largely buried in the hydrophobic interior of the membrane. These globular molecules are partially embedded in a matrix of phospholipid. The bulk of the phospholipid is organized as a discontinuous, fluid bilayer, although a small fraction of the lipid may interact specifically with the membrane proteins. The fluid mosaic structure is therefore formally analogous to a two-dimensional oriented solution of integral proteins (or lipoproteins) in the viscous phospholipid bilayer solvent. Recent experiments with a wide variety of techniqes and several different membrane systems are described, all of which abet consistent with, and add much detail to, the fluid mosaic model. It therefore seems appropriate to suggest possible mechanisms for various membrane functions and membrane-mediated phenomena in the light of the model. As examples, experimentally testable mechanisms are suggested for cell surface changes in malignant transformation, and for cooperative effects exhibited in the interactions of membranes with some specific ligands. Note added in proof: Since this article was written, we have obtained electron microscopic evidence (69) that the concanavalin A binding sites on the membranes of SV40 virus-transformed mouse fibroblasts (3T3 cells) are more clustered than the sites on the membranes of normal cells, as predicted by the hypothesis represented in Fig. 7B. T-here has also appeared a study by Taylor et al. (70) showing the remarkable effects produced on lymphocytes by the addition of antibodies directed to their surface immunoglobulin molecules. The antibodies induce a redistribution and pinocytosis of these surface immunoglobulins, so that within about 30 minutes at 37 degrees C the surface immunoglobulins are completely swept out of the membrane. These effects do not occur, however, if the bivalent antibodies are replaced by their univalent Fab fragments or if the antibody experiments are carried out at 0 degrees C instead of 37 degrees C. These and related results strongly indicate that the bivalent antibodies produce an aggregation of the surface immunoglobulin molecules in the plane of the membrane, which can occur only if the immunoglobulin molecules are free to diffuse in the membrane. This aggregation then appears to trigger off the pinocytosis of the membrane components by some unknown mechanism. Such membrane transformations may be of crucial importance in the induction of an antibody response to an antigen, as well as iv other processes of cell differentiation.

7,790 citations

Journal ArticleDOI
28 Jan 2005-Science
TL;DR: The new generations of qdots have far-reaching potential for the study of intracellular processes at the single-molecule level, high-resolution cellular imaging, long-term in vivo observation of cell trafficking, tumor targeting, and diagnostics.
Abstract: Research on fluorescent semiconductor nanocrystals (also known as quantum dots or qdots) has evolved over the past two decades from electronic materials science to biological applications. We review current approaches to the synthesis, solubilization, and functionalization of qdots and their applications to cell and animal biology. Recent examples of their experimental use include the observation of diffusion of individual glycine receptors in living neurons and the identification of lymph nodes in live animals by near-infrared emission during surgery. The new generations of qdots have farreaching potential for the study of intracellular processes at the single-molecule level, high-resolution cellular imaging, long-term in vivo observation of cell trafficking, tumor targeting, and diagnostics.

7,499 citations


"Dynamics in the plasma membrane: ho..." refers background in this paper

  • ...The use of fluorescent quantum dots is emerging as a promising alternative to classical fluorescent tags (GFPs and organic fluorophores) (Michalet et al, 2005)....

    [...]

  • ...…quantum yields, large molar extinction coefficients, size-dependent tunable emission and high photostability) make them appeal- &2006 European Molecular Biology Organization The EMBO Journal VOL 25 | NO 15 | 2006 3449 ing candidate tags for use with SDT (Dahan et al, 2003; Michalet et al, 2005)....

    [...]

Journal ArticleDOI
TL;DR: This review looks at current methods for preparing QD bioconjugates as well as presenting an overview of applications, and concludes that the potential of QDs in biology has just begun to be realized and new avenues will arise as the ability to manipulate these materials improves.
Abstract: One of the fastest moving and most exciting interfaces of nanotechnology is the use of quantum dots (QDs) in biology. The unique optical properties of QDs make them appealing as in vivo and in vitro fluorophores in a variety of biological investigations, in which traditional fluorescent labels based on organic molecules fall short of providing long-term stability and simultaneous detection of multiple signals. The ability to make QDs water soluble and target them to specific biomolecules has led to promising applications in cellular labelling, deep-tissue imaging, assay labelling and as efficient fluorescence resonance energy transfer donors. Despite recent progress, much work still needs to be done to achieve reproducible and robust surface functionalization and develop flexible bioconjugation techniques. In this review, we look at current methods for preparing QD bioconjugates as well as presenting an overview of applications. The potential of QDs in biology has just begun to be realized and new avenues will arise as our ability to manipulate these materials improves.

5,875 citations


"Dynamics in the plasma membrane: ho..." refers background in this paper

  • ...However, there is still a need to improve the functionalization of QD surfaces, the flexibility for bioconjugations and single irreversible molecular associations between individually tracked molecules (Medintz et al, 2005)....

    [...]

Book
01 Jan 1983
TL;DR: This book is a lucid, straightforward introduction to the concepts and techniques of statistical physics that students of biology, biochemistry, and biophysics must know.
Abstract: This book is a lucid, straightforward introduction to the concepts and techniques of statistical physics that students of biology, biochemistry, and biophysics must know. It provides a sound basis for understanding random motions of molecules, subcellular particles, or cells, or of processes that depend on such motion or are markedly affected by it. Readers do not need to understand thermodynamics in order to acquire a knowledge of the physics involved in diffusion, sedimentation, electrophoresis, chromatography, and cell motility--subjects that become lively and immediate when the author discusses them in terms of random walks of individual particles.

3,041 citations


"Dynamics in the plasma membrane: ho..." refers background in this paper

  • ...Brownian motion is a principle that applies to all biological systems (Berg, 1983): as the result of thermal agitation processes, molecules are constantly on the move, colliding with each other and bouncing back and forth (Figure 1)....

    [...]

  • ...…plasma membrane dynamics Brownian motion, diffusion and membrane organization Brownian motion is a principle that applies to all biological systems (Berg, 1983): as the result of thermal agitation processes, molecules are constantly on the move, colliding with each other and bouncing back and…...

    [...]

Journal ArticleDOI
TL;DR: A unified characterization of the best available FPs provides a useful guide in narrowing down the options for biological imaging tools.
Abstract: The recent explosion in the diversity of available fluorescent proteins (FPs) promises a wide variety of new tools for biological imaging. With no unified standard for assessing these tools, however, a researcher is faced with difficult questions. Which FPs are best for general use? Which are the brightest? What additional factors determine which are best for a given experiment? Although in many cases, a trial-and-error approach may still be necessary in determining the answers to these questions, a unified characterization of the best available FPs provides a useful guide in narrowing down the options.

2,933 citations


"Dynamics in the plasma membrane: ho..." refers background in this paper

  • ...As the cDNA encoding the GFP was characterized, a wide variety of monomeric fluorescent proteins have provided attractive potential candidates for monitoring dynamic processes in which different molecular species are simultaneously involved (for a review, see Shaner et al, 2005)....

    [...]