Membranes et fonctions cellulaires

Publications

Année de publication : 2015

Mijo Simunovic, Gregory A Voth, Andrew Callan-Jones, Patricia Bassereau (2015 Nov 2)

When Physics Takes Over: BAR Proteins and Membrane Curvature.

Trends in cell biology : 780-92 : DOI : 10.1016/j.tcb.2015.09.005 En savoir plus
Résumé

Cell membranes Become highly curved During membrane trafficking, cytokinesis, infection, immune response, or cell motion. Bin / Amphiphysin / Rvs (BAR) domain proteins Intrinsically With Their curved shape anisotropy and are Involved in Many of These processes, aim with a wide spectrum of modes of action. In vitro experiments and computer simulations multiscale-have Contributed in Identifying a minimal set of physical parameters derived derived, namely protein density on the membrane, membrane voltage and membrane shape, That control how bound BAR domain proteins behave on the membrane. In this review, we summarize the multifaceted BAR coupling of proteins to membrane mechanics and offers a single-phase diagram That Recapitulates the effects of These parameters.

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Thibaut J Lagny, Patricia Bassereau (2015 Oct 15)

Bioinspired membrane-based systems for a physical approach of cell organization and dynamics: usefulness and limitations.

Interface focus : 20150038 : DOI : 10.1098/rsfs.2015.0038 En savoir plus
Résumé

Being at the Periphery of Each cell compartment and enclosing the Entire cell while interacting with a large part of cell components, cell membranes Participate in MOST of the cell’s vital functions. Biologists-have for a long time Worked on deciphering how membranes are Organized, How They contribuer to trafficking, motility, cytokinesis, cell-cell communication, transport information, etc., using top-down Approaches and always more advanced techniques. In contrast, physicists-have Developed bottom-up Approaches and minimal model membrane systems of growing complexity in order to build up general models That explain how cell membranes work and How They interact with proteins, eg the cytoskeleton. We review the different model membrane systems That ares currently available, and How They can help deciphering cell functioning, goal aussi Their list limitations. Model membrane systems are aussi used in synthetic biology and can-have potential applications beyond basic research. We can the Chat the synergy entre le development of complex membrane systems in vitro in a biological context and for technological applications. Questions That Could aussi be Discussed are: what can we still do with synthetic systems, where do we stop building up and qui are the alternative solutions?

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Monica Rolando, Caroline Stefani, Anne Doye, Maria I Acosta, Orane Visvikis, Hannah G Yevick, Carmen Buchrieser, Amel Mettouchi, Patricia Bassereau, Emmanuel Lemichez (2015 Sep 26)

Contractile actin cables induced by Bacillus anthracis lethal toxin depend on the histone acetylation machinery.

Cytoskeleton (Hoboken, N.J.) : 542-56 : DOI : 10.1002/cm.21256 En savoir plus
Résumé

It remains a challenge to decode the molecular basis of the long-term actin cytoskeleton rearrangements That are-governed by the reprogramming of gene expression. Bacillus anthracis lethal toxin (LT) Inhibits mitogen-activated protein kinase (MAPK) signaling, thereby modulating gene expression, with major consequences for actin cytoskeleton organization and the loss of endothelial barrier function. Using a laser ablation approach, we caractérisé the contractile and tensile mechanical properties of LT-induced stress fibers. These actin cables resist pulling force That Transmitted are at cell-matrix interfaces and at cell-cell adherens junctions discontinuous. We carry That Treating the cells with trichostatin A (TSA), a broad inhibitor of histone deacetylases Range (HDACs), or with MS-275, qui targets HDAC1, 2 and 3, induces stress fibers. LT Decreased the cellular levels of HDAC1, 2 and 3 and the Reduced total HDAC activity in the nucleus. Both the LT and TSA treatments Rnd3 induced expression, qui est required for the LT-mediated induction of actin stress fibers. Furthermore, we reveal That Treating the cells intoxicated with LT-garcinol, an inhibitor of histone acetyl transferases (HATs) disrupts the stress fibers and limits the monolayer barrier dysfunctions. These data Demonstrate the importance of modulating the flow of protein acetylation in order to control actin cytoskeleton organization and the endothelial cell monolayer barrier.

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Mijo Simunovic, Ka Yee C Lee, Patricia Bassereau (2015 May 29)

Celebrating Soft Matter’s 10th anniversary: screening of the calcium-induced spontaneous curvature of lipid membranes.

Soft matter : 5030-6 : DOI : 10.1039/c5sm00104h En savoir plus
Résumé

Lipid membranes are key regulators of cellular function. An significant step in membrane-related phenomena is the reshaping of the lipid bilayer, Often induced by binding of macromolecules. Numerous experimental and simulation efforts-have Revealed That calcium, a ubiquitous cellular messenger: has a strong impact on the behavior stage, structural properties, and the stability of membranes. Yet, it is still unknown the way calcium and lipid interactions affect Their macroscopic mechanical properties. In this work, we Studied the interaction of calcium ions with membrane tethers pulled from giant unilamellar vesicles, QUANTIFY to the mechanical effect on the membrane. We found calcium That imposed a positive spontaneous curvature is Negatively charged membranes Contrary to predictions we made based on the Proposed atomic structure. Surprisingly, this effect vanishes in the presence of physiologically relevant concentrations of sodium chloride. Our work Implies That calcium May be a trigger for reshaping membrane only at high concentrations, in a process robustly That is screened by sodium ions.

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Ludger Johannes, Robert G Parton, Patricia Bassereau, Satyajit Mayor (2015 Apr 11)

Building endocytic pits without clathrin.

Nature reviews. Molecular cell biology : 311-21 : DOI : 10.1038/nrm3968 En savoir plus
Résumé

How endocytic pits are built in clathrin- and caveolin-independent endocytosis still remains poorly Understood. Recent insight Suggests That different forms of clathrin-independent endocytosis might Involve the actin-driven focusing of membrane constituents, the lectin-glycosphingolipid-dependent endocytic nanoenvironments of building, and Bin-Amphiphysin-Rvs (BAR) domain proteins serving as scaffolding modules. We need the Chat for the different kinds of internalization processes in the context of diverse cellular functions, the existence of clathrin-independent Mechanisms of cargo recruitment and membrane bending from a physical and biological perspective, and finally propose a generic scheme for the formation of clathrin- independent endocytic pits.

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Matthias Garten, Coline Prévost, Clotilde Cadart, Romain Gautier, Luc Bousset, Ronald Melki, Patricia Bassereau, Stefano Vanni (2015 Apr 1)

Methyl-branched lipids promote the membrane adsorption of α-synuclein by enhancing shallow lipid-packing defects.

Physical chemistry chemical physics : PCCP : 15589-97 : DOI : 10.1039/c5cp00244c En savoir plus
Résumé

Alpha-synuclein (AS) is a synaptic protein That Is Directly Involved in Parkinson’s disease due to ict tendency to form protein aggregates. Since AS aggregation can be dependent on the interactions entre les protein and the cell plasma membrane, elucidating the membrane binding properties of AS is of crucial importance to the suit les molecular basis of AS aggregation into toxic fibrils. Using a combination of in vitro reconstitution experiments based on Giant Unilamellar Vesicles (GUVs), confocal microscopy and all-atom molecular dynamics simulations, we-have Investigated the membrane binding properties of AS, with a focus on the relative contribution of hydrophobic versus electrostatic interactions. In contrast with previous observations, We Did not observed Any binding of AS to membranes Containing the ganglioside GM1, GM1-even at high Relatively happy. AS we Reviews the other hand, Showed a stronger affinity for neutral flat membranes consistant en methyl-branched lipids. To rationalize thesis results, we used all-atom molecular dynamics simulations to Investigate the effect of methyl-branched lipids is membrane interfacial properties. We found That methyl-branched lipids Promote the membrane adsorption of AS by Creating shallow lipid-packing defects to a larger extent than polyunsaturated and monounsaturated lipids. Our Findings suggest methyl-branched lipids That May Constitute a substrate for adhesive Remarkably peripheral proteins adsorbed That is hydrophobic membranes via inserts.

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Coline Prévost, Hongxia Zhao, John Manzi, Emmanuel Lemichez, Pekka Lappalainen, Andrew Callan-Jones*, Patricia Bassereau* (2015 Feb 26)

IRSp53 senses negative membrane curvature and phase separates along membrane tubules.

Nature communications : 8529 : DOI : 10.1038/ncomms9529 En savoir plus
Résumé

BAR domain proteins to membrane deformation contribute in diverse cellular processes. The inverted-BAR (I-BAR) IRSp53 protein, for instance, is found on the inner leaflet of the tubular membrane of filopodia; HOWEVER icts role in the formation of These structures is incompletely Understood. Here we Develop an original assay in which proteins are encapsulated in unilamellar giant vesicles connected to membrane nanotubes. Our results Demonstrate That I-BAR dimers sense negative curvature membrane. Experiment and theory reveal that the I-BAR displays a non-monotonic sorting with curvature, and Expands the tube at high voltage Imposed while constricting it at low voltage. Strikingly, at low protein density and pressure, protein-rich domains APPEAR along the tube. This peculiar behavior is due to the shallow intrinsic curvature of I-BAR dimers. It allows constriction of weakly curved membranes coupled to local protein enrichment at biologically relevant conditions. This might explain how IRSp53 Contributes to the in vivo induction of filopodia.

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Senthil Arumugam, Patricia Bassereau (2015 Feb 7)

Membrane nanodomains: contribution of curvature and interaction with proteins and cytoskeleton.

Essays in biochemistry : 109-19 : DOI : 10.1042/bse0570109 En savoir plus
Résumé

The understanding of lipid membranes and Their organization HAS Undergone significant development with better technology and more The Therefore resolved experiments. Many new factoring and organizing principles-have-been Discovered, and interplay entre thesis factoring is expected to result in rich functional Behaviours. The major factoring regulating the lateral heterogeneity membrane, apart from the well-Studied stage separation, are pinning cytoskeleton, clustering of lipids and curvature. These are factoring effective means clustering to create rich membrane domains That Provide biological functions on. We review the recent advances and concepts of heterogeneity membrane curvature by organization, clustering and cytoskeleton proteins.

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Matthias Garten, Sophie Aimon, Patricia Bassereau, Gilman E S Toombes (2015 Feb 5)

Reconstitution of a transmembrane protein, the voltage-gated ion channel, KvAP, into giant unilamellar vesicles for microscopy and patch clamp studies.

Journal of visualized experiments : JoVE : 52281 : DOI : 10.3791/52281 En savoir plus
Résumé

Giant Unilamellar Vesicles (GUVs) are a popular biomimetic system for studying membrane associated phenomena. HOWEVER, Commonly used protocols to grow GUVs must be modified in order to form GUVs Containing functional transmembrane proteins. This Article Describes two dehydration-rehydration methods – electroformation and gel-assisted swelling – to form GUVs Containing the voltage-gated potassium channel, KvAP. In Both methods, a solution of protein-containing small unilamellar vesicles is Partially dehydrated to form a stack of membranes, qui est Then allowed to swell in a rehydration buffer. For the electroformation method, the movie is Deposited on platinum electrodes so That year AC field Can Be Applied During rehydration movie. In contrast, the gel-assisted swelling method uses an agarose gel substrate to Enhance movie rehydration. Both methods can Produce GUVs in low (eg, 5 mM) and physiological (eg, 100 mM) salt concentrations. The resulting and GUVs are caractérisé via fluorescence microscopy, and the function of reconstituted channels Measured using the inside-out patch-clamp configuration. While swelling in the presence of an alternating electric field (electroformation) Gives a high yield of defect-free GUVs, the gel-assisted method swelling Produces a more homogeneous protein distribution and requires no special equipment.

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Renard HF, Simunovic M, Lemière J, Boucrot E, Garcia-Castillo MD, Arumugam S, Chambon V, Lamaze C, Wunder C, Kenworthy AK, Schmidt AA, McMahon HT, Sykes C*, Bassereau P*, Johannes L (2015 Jan 22)

Endophilin-A2 functions in membrane scission in clathrin-independent endocytosis

Nature : 517 : 493-6 : DOI : 10.1038/nature14064 En savoir plus
Résumé

During endocytosis, energy is Invested to narrow necks of the cargo-containing plasma membrane invaginations to radii at the Opposing segments That coalesce spontaneously, thereby leading to the detachment by scission of endocytic uptake carriers. In the clathrin pathway, dynamin uses mechanical energy from GTP hydrolysis to this effect, assisted by the BIN / Amphiphysin / Rvs (BAR) domain-containing protein Endophilin. Clathrin-independent endocytic events are less connecting Often we dynamin, and whether in contention boxes BAR domain proteins Such As Endophilin contribuer to split HAS Remained unexplored. Here we show, in human and mammalian cell lines –other, That Endophilin-A2 (endoA2) SPECIFICALLY and functionally associates with very early uptake structures are induced by the bacterial Shiga toxins and cholera That, qui Both are clathrin-independent endocytic cargoes. In controlled in vitro systems, endoA2 reshapes membranes before split. Furthermore, we Demonstrate That endoA2, dynamin and actin contribuer in parallel to the split of Shiga-toxin-induced tubules. Our results Follows has the novel function of endoA2 in clathrin-independent endocytosis. They separate paper That split factoring operate in an additive Manner, and predict That specificity Within a Given uptake process Arises from defined combinations of universal modules. Our Findings highlight a link entre Previously unnoticed by endoA2 membrane scaffolding and pulling-force-driven dynamic split.

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Année de publication : 2014

Ayako Yamada, Sungyon Lee, Patricia Bassereau, Charles N Baroud (2014 Jun 17)

Trapping and release of giant unilamellar vesicles in microfluidic wells.

Soft matter : 5878-85 : DOI : 10.1039/c4sm00065j En savoir plus
Résumé

We describe the trapping and release of giant unilamellar vesicles (GUVs) in a thin and wide microfluidic channel, As They cross indentations etched in the channel ceiling. This trapping results from the reduction of the membrane elastic energy, qui est Stored in the GUV as it squeezes to enter into the thin channel. We Demonstrate That GUVs Whose diameter is Slightly larger than the channel height can be trapped and That They Can be untrapped by the outer fluid flowing beyond a critical velocity. GUVs smaller than the flow channel height undisturbed while much larger Those can not squeeze into the thin regions. Within the ranks That allows trapping, larger GUVs are anchored more than smaller Strongly GUVs. The Ability to trap vesicles Provides access to the optical GUVs for extended Periods of time; this allows the observation of recirculation flow on the surface area of ​​the GUVs, in the direction of forward near the mid-plane of the channel and in the reverse direction of elsewhere. We also obtenir the shape of GUVs under different flow requirements through confocal microscopy. This geometric information is used to drift a mechanical model of the power balance That equates the viscous effects from the outer flow with the elastic effects based on the variation of the membrane stretching energy. This model yields Good agreement with the experimental data values ​​When stretching of the moduli are taken from the scientific literature. This microfluidic approach Provides a New Way of Storing a wide number of GUVs at specific locations, with or without the presence of an outer flow. As Such, it was deriving their high-throughput alternative to micropipette manipulation of individual chemical or biological GUVs for applications.

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Laura Picas, Julien Viaud, Kristine Schauer, Stefano Vanni, Karim Hnia, Vincent Fraisier, Aurélien Roux, Patricia Bassereau, Frédérique Gaits-Iacovoni, Bernard Payrastre, Jocelyn Laporte, Jean-Baptiste Manneville, Bruno Goud (2014 May 19)

BIN1/M-Amphiphysin2 induces clustering of phosphoinositides to recruit its downstream partner dynamin.

Nature communications : 5647 : DOI : 10.1038/ncomms6647 En savoir plus
Résumé

Phosphoinositide play a central role in physiological processes by Many Assisting the recruitment of proteins to membranes through specific phosphoinositide-binding motifs. How is this recruitment Coordinated in space and time is not well Understood. Here we show That BIN1 / M-Amphiphysin2, a protein Involved in T-tubule biogenesis in muscle cells and frequently mutated in centronuclear myopathies, clusters PtdIns (4,5) P2 to recruit ict downstream partner dynamin. By using Several mutants associated with centronuclear myopathies, we find that N-BAR and the SH3 domains of BIN1 control the kinetics and the accumulation of dynamin we membranes, respectively. We that show phosphoinositide Clustering is a mechanism shared by –other That proteins interact with PtdIns (4,5) P2, do not aim to contain a BAR domain. Our numerical simulations Point Out That clustering is a diffusion-driven process in which molecules are not sequestered phosphoinositide. We propose That this mechanism plays a key role in the recruitment of downstream phosphoinositide-binding proteins.

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Ayako Yamada, Alexandre Mamane, Jonathan Lee-Tin-Wah, Aurélie Di Cicco, Coline Prévost, Daniel Lévy, Jean-François Joanny, Evelyne Coudrier*, Patricia Bassereau* (2014 Apr 7)

Catch-bond behaviour facilitates membrane tubulation by non-processive myosin 1b.

Nature communications : 3624 : DOI : 10.1038/ncomms4624 En savoir plus
Résumé

Myosin 1b is a single-headed membrane-associated motor actin filaments to That Bind with a catch-hop behavior in response to load. In vivo, myosin 1b is required to form membrane tubules at Both endosomes and the trans-Golgi network. To suit les the link entre thesis Fundamental two properties, here we Investigate the capacity of myosin 1b to extract membrane tubes along bundled actin filaments in a minimum reconstituted system. We that show single-headed non-processive myosin 1b can extract membrane tubes at biologically relevant low density. In contrast to kinesins we do not observe motor accumulation at the tip, Suggesting que la Underlying mechanism for tube formation is different. In our theoretical model, myosin 1b catch-bond properties Facilitate tube extraction under the conditions of membrane voltage by Increasing Reducing the density of myo1b required to pull tubes.

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François Quemeneur, Jon K Sigurdsson, Marianne Renner, Paul J Atzberger*, Patricia Bassereau*, David Lacoste* (2014 Mar 24)

Shape matters in protein mobility within membranes.

Proceedings of the National Academy of Sciences of the United States of America : 5083-7 : DOI : 10.1073/pnas.1321054111 En savoir plus
Résumé

The lateral mobility of proteins within cell membranes is usually thought to be dependent on their size and modulated by local heterogeneities of the membrane. Experiments using single-particle tracking on reconstituted membranes demonstrate that protein diffusion is significantly influenced by the interplay of membrane curvature, membrane tension, and protein shape. We find that the curvature-coupled voltage-gated potassium channel (KvAP) undergoes a significant increase in protein mobility under tension, whereas the mobility of the curvature-neutral water channel aquaporin 0 (AQP0) is insensitive to it. Such observations are well explained in terms of an effective friction coefficient of the protein induced by the local membrane deformation.

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Patricia Bassereau, Benoit Sorre, Aurore Lévy (2014 Mar 18)

Bending lipid membranes: experiments after W. Helfrich’s model.

Advances in colloid and interface science : 47-57 : DOI : 10.1016/j.cis.2014.02.002 En savoir plus
Résumé

Current description of biomembrane mechanics for a large part originates from W. Helfrich’s model. Based On His continuum theory, Many experiments-have-been Performed in the past four Decades membranes is simplified in order to Characterize the mechanical properties of lipid membranes and the contribution of polymers or proteins. The long-term goal Was to Develop a better understanding of the mechanical properties of cell membranes. In this paper, we will review experimental representative Approaches That Were Developed During this period and the hand results That Were therefor obtained.

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