Fabrication of three-dimensional electrical connections by means of directed actin self-organization

Galland, Rémi; Leduc, P.; Guérin, Christophe; Peyrade, D.; Blanchoin, Laurent; Théry, Manuel

doi:10.1038/nmat3569

Cited by 57 publications

(52 citation statements)

References 31 publications

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Section: Branched Actin Networkmentioning

confidence: 99%

“…3,4,115,150,233,256). Instead, capping protein or proteins with similar activities work in synergy with the Arp2/3 complex to build a dense actin network of capped filaments that are sterically displaced by new branches formed at NPF sites (3,4,25,96,150,351).In the presence of capping proteins, the mechanism of activation of the Arp2/3 complex results in an actin network that should not be viewed as a homogeneous structure at the filament scale, but as a combination of subnetworks, each seeded by different primers. These subnetworks merge together depending on the biochemical conditions to build a homogeneous network that can generate a force due to entanglement of new branches generated at the NPF sites.…”

mentioning

confidence: 99%

“…studies concerning the mechanical properties and force generation of branched networks, no clear consensus has emerged relating the detailed actin structure to how good the actin network is at moving an object (3,4,20,87,195,257,338). New methods using NPF-micropatterning to orient actin network growth and control its geometry in combination with physical methods to measure force production, such as magnetic colloids in magnetic fields, atomic force microscopy, or optical tweezers, should make it possible in the future to correlate the biochemical composition of the actin network and its microscopic organization to the force generated by the network (34,59,96,217,252,256). …”

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confidence: 99%

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Actin Dynamics, Architecture, and Mechanics in Cell Motility

Blanchoin

Boujemaa-Paterski

Sykes

et al. 2014

Physiological Reviews

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1,202

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Tight coupling between biochemical and mechanical properties of the actin cytoskeleton drives a large range of cellular processes including polarity establishment, morphogenesis, and motility. This is possible because actin filaments are semi-flexible polymers that, in conjunction with the molecular motor myosin, can act as biological active springs or "dashpots" (in laymen's terms, shock absorbers or fluidizers) able to exert or resist against force in a cellular environment. To modulate their mechanical properties, actin filaments can organize into a variety of architectures generating a diversity of cellular organizations including branched or crosslinked networks in the lamellipodium, parallel bundles in filopodia, and antiparallel structures in contractile fibers. In this review we describe the feedback loop between biochemical and mechanical properties of actin organization at the molecular level in vitro, then we integrate this knowledge into our current understanding of cellular actin organization and its physiological roles. I. PREFACE ON ACTIN ORGANIZATION AND CELL MECHANICSAnimal cells (i.e., those without a cell wall) have the ability to change their shape to adapt to their environment, move through narrow spaces, divide, or allow exo-and endocytosis. The machinery of these shape changes relies on the assembly of proteins, in particular actin, a globular protein that polymerizes into filaments of different types of organization: branched and crosslinked networks, parallel bundles, and anti-parallel contractile structures (FIGURE 1A). These different architectures can be envisioned as a series of interconnected active springs and dashpots (green and red symbols in FIGURE 1B, respectively) that act as mechanical elements to drive cell shape changes and motility. The purpose of this review is to correlate recent progress in our understanding of the interplay between biochemical elements and mechanical properties. Instead of describing biochemical and mechanical properties separately, our main goal here is to address piece by piece the integrated feedback loop between biochemistry and mechanics.At the front of the cell, branched and crosslinked networks in a quasi two-dimensional sheet make up the lamellipodium, and are the major engine of cell movement since they push the cell membrane by polymerizing against it (FIGURE 1A, iii). Aligned bundles underlie filopodia that are the fingerlike structures at the front of the cell, important for directional response of the cell (FIGURE 1A, iv). A thin layer of actin, called the cell cortex, coats the plasma membrane at the back and sides of the cell, important for cell shape maintenance and changes (FIGURE 1A, i). The rest of the cell contains a three-dimensional network of crosslinked filaments interspersed with contractile bundles, including stress fibers that connect the cell cytoskeleton to the extracellular matrix via focal adhesion sites (FIGURE 1A, ii). Contraction in the cell is produced by the molecular motor protein myosin. Myosin assembles into anti...

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Section: Branched Actin Networkmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Actin Dynamics, Architecture, and Mechanics in Cell Motility

Blanchoin

Boujemaa-Paterski

Sykes

et al. 2014

Physiological Reviews

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1,202

1,145

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“…The similarity of the patterns displayed by these systems lead many to address the general principles behind their formation using simple models [6]. The reproducibility and robustness of the phenomena under a variety of external conditions motivated a large body of research on selfassembly of active particle as a possible strategy towards the fabrication of new functional nano-and mesoscopic structures [7]. In this respect there have been several efforts to study active self-organisation in a tightly controlled environment; the most studied systems being selfpropelled particles [6,[8][9][10][11] and active gels (e.g.…”

Section: Pacs Numbersmentioning

confidence: 99%

Living Clusters and Crystals from Low-Density Suspensions of Active Colloids

et al. 2013

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Recent studies aimed at investigating artificial analogues of bacterial colonies have shown that lowdensity suspensions of self-propelled particles confined in two dimensions can assemble into finite aggregates that merge and split, but have a typical size that remains constant (living clusters). In this Letter we address the problem of the formation of living clusters and crystals of active particles in three dimensions. We study two systems: self-propelled particles interacting via a generic attractive potential and colloids that can move towards each other as a result of active agents (e.g. by molecular motors). In both cases fluid-like 'living' clusters form. We explain this general feature in terms of the balance between active forces and regression to thermodynamic equilibrium. This balance can be quantified in terms of a dimensionless number that allows us to collapse the observed clustering behaviour onto a universal curve. We also discuss how active motion affects the kinetics of crystal formation. PACS numbers:Active systems consume energy that keeps them in an out-of-equilibrium state [1,2]. This is typical for many biologically relevant systems which, by exploiting chemical energy, can self-organise into complex structures that lack any equilibrium counterpart. Examples are abundant and exist at different length-scales: from cytoskeleton remodulation during cell mitosis [3] to swarming phenomena in micro-swimmers or flocks of birds [4,5]. The similarity of the patterns displayed by these systems lead many to address the general principles behind their formation using simple models [6]. The reproducibility and robustness of the phenomena under a variety of external conditions motivated a large body of research on selfassembly of active particle as a possible strategy towards the fabrication of new functional nano-and mesoscopic structures [7]. In this respect there have been several efforts to study active self-organisation in a tightly controlled environment; the most studied systems being selfpropelled particles [6,[8][9][10][11] and active gels (e.g. [12]).Recently, two experimental groups have shown how two-dimensional suspensions of self-propelled (SP) colloids (moving through the consumption of an appropriate 'fuel') self-assemble into dynamic clusters that constantly join and split, recombining with each other to reach a steady-state [13,14]. A general understanding of active cluster formation is lacking, but different explanations have been proposed. The authors of Ref.[13] argued that a net attraction between colloids is responsible for clustering. This attraction is due to non-uniformity in the chemical fuel concentration between two colloids. This was confirmed by Ref. [14], that also found a 1/d 2 dependence of the particle-particle attraction ( d being the inter-particle distance). The formation of finite-size clusters has been also observed in low density bacteria/polymer suspensions, at intermediate polymer concentrations just before phase separation [10]. However, in other recent studi...

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“…Novel approaches based on the dynamic self-assembly of inorganic building blocks [13][14][15] , actin self-organization 16 and the combination of top-down processes with peptide self-assembly have been reported recently 17 . In particular, Stupp and co-workers have described a self-assembling membrane system obtained through strong electrostatic interactions between PAs and oppositely charged polysaccharides 18 .…”

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confidence: 99%

Co-assembly, spatiotemporal control and morphogenesis of a hybrid protein–peptide system

et al. 2015

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ature uses self-assembly to create a widespread variety of complex structures with elaborate geometries and outstanding properties 1 such as hierarchical order, adaptability, selfhealing and bioactivity. Developing new bioinspired processes based on dynamic self-assembly could facilitate the fabrication of synthetic three-dimensional (3D) materials with enhanced complexity, dynamic properties and functionality 2 . Proteins are particularly attractive building blocks because of their versatility and biofunctionality 3 . Elastin-like polypeptides (ELPs) 4 are recombinant proteins that have generated great interest 5 as a result of their modular structure, bioactivity, ease of design and production, and the possibility to create robust and elastic materials 5,6 . ELPs allow for a tunable molecular design 7 and are based on the tropoelastin recurrent motif Val-Pro-Gly-X-Gly (VPGXG), in which X is any amino acid other than proline 7 . This repeating pentapeptide provides ELPs with a thermoresponsive behaviour. Below a critical transition temperature (T t ), the ELP molecule undergoes a reversible-phase transition wherein the protein is soluble in aqueous solution and becomes highly solvated, surrounded by clatharate-like water structures. Above the T t , the hydrophobic domains dehydrate and the protein chain hydrophobically collapses and aggregates to form a phaseseparated state 8 .The use of natural and synthetic proteins to create functional materials has been hindered by the difficulty in controlling their conformation and nanoscale assembly with the precision required to form macroscopic materials. This limitation has driven the development of simpler and more-predictable peptide-based materials 9,10 . Peptide amphiphiles (PAs), for example, are synthetic molecules that can self-assemble into nanofibres and create functional 3D hydrogels that emulate the fibrous architecture of the extracellular matrix (ECM) 11,12 . Nonetheless, most peptide and/or protein materials are formed through equilibrium-based self-assembly approaches that are capable of generating stable supramolecular structures, but with limited hierarchy and spatiotemporal control, which has hindered their functionality 2 .Novel approaches based on the dynamic self-assembly of inorganic building blocks [13][14][15] , actin self-organization 16 and the combination of top-down processes with peptide self-assembly have been reported recently 17 . In particular, Stupp and co-workers have described a self-assembling membrane system obtained through strong electrostatic interactions between PAs and oppositely charged polysaccharides 18 . However, the possibility to exploit the unique structural and functional properties of proteins to create dynamic hierarchical materials remains an elusive target. In this study, we attempt to overcome this hurdle by using self-assembling peptides to promote protein conformational changes and guide their assembly into complex, yet functional, materials. We report the discovery and development of a protein/peptide system t...

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Fabrication of three-dimensional electrical connections by means of directed actin self-organization

Cited by 57 publications

References 31 publications

Actin Dynamics, Architecture, and Mechanics in Cell Motility

Actin Dynamics, Architecture, and Mechanics in Cell Motility

Living Clusters and Crystals from Low-Density Suspensions of Active Colloids

Co-assembly, spatiotemporal control and morphogenesis of a hybrid protein–peptide system

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