UMR168 – Physico-Chimie Curie Lab

Team Publications

Year of publication 2020

Cao Luyan, Yonis Amina, Vaghela Malti, Barriga Elias, Chugh Priyamvada, Smith Matthew, Maufront Julien, Lavoie Geneviève, Méant Antoine, Ferber Emma, Bovellan Miia, Alberts Art, Bertin Aurélie, Mayor Roberto, Paluch Eva, Roux Philippe, Jégou Antoine, Romet-Lemonne Guillaume, Charras Guillaume (2020 Jun 22)

SPIN90 associates with mDia1 and the Arp2/3 complex to regulate cortical actin organization

Nature Cell BiologyNature Cell Biology : DOI : 10.1038/s41556-020-0531-y Learn more
Summary

Cell shape is controlled by the submembranous cortex, an actomyosin network mainly generated by two actin nucleators: the Arp2/3 complex and the formin mDia1. Changes in relative nucleator activity may alter cortical organization, mechanics and cell shape. Here we investigate how nucleation-promoting factors mediate interactions between nucleators. In vitro, the nucleation-promoting factor SPIN90 promotes formation of unbranched filaments by Arp2/3, a process thought to provide the initial filament for generation of dendritic networks. Paradoxically, in cells, SPIN90 appears to favour a formin-dominated cortex. Our in vitro experiments reveal that this feature stems mainly from two mechanisms: efficient recruitment of mDia1 to SPIN90–Arp2/3 nucleated filaments and formation of a ternary SPIN90–Arp2/3–mDia1 complex that greatly enhances filament nucleation. Both mechanisms yield rapidly elongating filaments with mDia1 at their barbed ends and SPIN90–Arp2/3 at their pointed ends. Thus, in networks, SPIN90 lowers branching densities and increases the proportion of long filaments elongated by mDia1.

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Aurélie Bertin , Nicola de Franceschi , Eugenio de la Mora , Sourav Maiti, Maryam Alqabandi, Nolwen Miguet, Aurélie di Cicco, Wouter H. Roos, Stéphanie Mangenot , Winfried Weissenhorn, Patricia Bassereau (2020 May 29)

Human ESCRT-III polymers assemble on positively curved membranes and induce helical membrane tube formation

Nature Communications : 11 : 2663 : DOI : 10.1038/s41467-020-16368-5 Learn more
Summary

Endosomal sorting complexes for transport-III (ESCRT-III) assemble in vivo onto membranes with negative Gaussian curvature. How membrane shape influences ESCRT-III polymerization and how ESCRT-III shapes membranes is yet unclear. Human core ESCRT-III proteins, CHMP4B, CHMP2A, CHMP2B and CHMP3 are used to address this issue in vitro by combining membrane nanotube pulling experiments, cryo-electron tomography and AFM. We show that CHMP4B filaments preferentially bind to flat membranes or to tubes with positive mean curvature. Both CHMP2B and CHMP2A/CHMP3 assemble on positively curved membrane tubes. Combinations of CHMP4B/CHMP2B and CHMP4B/CHMP2A/CHMP3 are recruited to the neck of pulled membrane tubes and reshape vesicles into helical “corkscrewlike” membrane tubes. Sub-tomogram averaging reveals that the ESCRT-III filaments assemble parallel and locally perpendicular to the tube axis, highlighting the mechanical stresses imposed by ESCRT-III. Our results underline the versatile membrane remodeling activity of ESCRT-III that may be a general feature required for cellular membrane remodeling processes.

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Year of publication 2019

Mijo Simunovic, Emma Evergren, Andrew Callan-Jones*, Patricia Bassereau* (2019 Oct 7)

Curving Cells Inside and Out: Roles of BAR Domain Proteins in Membrane Shaping and Its Cellular Implications.

Annual Review of Cell and Developmental Biology : 35 : DOI : 10.1146/annurev-cellbio-100617-060558 Learn more
Summary

Many cellular processes rely on precise and timely deformation of the cell membrane. While many proteins participate in membrane reshaping and scission, usually in highly specialized ways, Bin/amphiphysin/Rvs (BAR) domain proteins play a pervasive role, as they not only participate in many aspects of cell trafficking but also are highly versatile membrane remodelers. Subtle changes in the shape and size of the BAR domain can greatly impact the way in which BAR domain proteins interact with the membrane. Furthermore, the activity of BAR domain proteins can be tuned by external physical parameters, and so they behave differently depending on protein surface density, membrane tension, or membrane shape. These proteins can form 3D structures that mold the membrane and alter its liquid properties, even promoting scission under various circumstances. As such, BAR domain proteins have numerous roles within the cell. Endocytosis is among the most highly studied processes in which BAR domain proteins take on important roles. Over the years, a more complete picture has emerged in which BAR domain proteins are tied to almost all intracellular compartments; examples include endosomal sorting and tubular networks in the endoplasmic reticulum and T-tubules. These proteins also have a role in autophagy, and their activity has been linked with cancer. Here, we briefly review the history of BAR domain protein discovery, discuss the mechanisms by which BAR domain proteins induce curvature, and attempt to settle important controversies in the field. Finally, we review BAR domain proteins in the context of a cell, highlighting their emerging roles in cell signaling and organelle shaping.

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Attner MA*, Keil W*, Benavidez JM, Greenwald I (2019 Sep 23)

HLH-2/E2A Expression Links Stochastic and Deterministic Elements of a Cell Fate Decision during C. elegans Gonadogenesis

Current Biology : 29 : 1-7 : DOI : https://doi.org/10.1016/j.cub.2019.07.062 Learn more
Summary

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Moitrier Sarah, Pricoupenko Nastassia, Kerjouan Adèle, Oddou Christiane, Destaing Olivier, Battistella Aude, Silberzan Pascal, Bonnet Isabelle (2019 Sep 3)

Local light-activation of the Src oncoprotein in an epithelial monolayer promotes collective extrusion

Communications Physics : 2 : 98 : DOI : 10.1038/s42005-019-0198-5 Learn more
Summary

Transformed isolated cells are usually extruded from normal epithelia and subsequently eliminated. However, multicellular tumors outcompete healthy cells, highlighting the importance of collective effects. Here, we investigate this situation in vitro by controlling in space and time the activity of the Src oncoprotein within a normal Madin–Darby Canine Kidney (MDCK) epithelial cell monolayer. Using an optogenetics approach with cells expressing a synthetic light-sensitive version of Src (optoSrc), we reversibly trigger the oncogenic activity by exposing monolayers to well-defined light patterns. We show that small populations of activated optoSrc cells embedded in the non-transformed monolayer collectively extrude as a tridimensional aggregate and remain alive, while the surrounding normal cells migrate towards the exposed area. This phenomenon requires an interface between normal and transformed cells and is partially reversible. Traction forces show that Src- activated cells either actively extrude or are pushed out by the surrounding cells in a non- autonomous way.

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Zack Jarin, Feng-Ching Tsai, Aram Davtyan, Alexander J.Pak, Patricia Bassereau, Gregory A.Voth (2019 Aug 6)

Unusual Organization of I-BAR Proteins on Tubular and Vesicular Membranes.

Biophysical Journal : 117 : 553-562 : DOI : 10.1016/j.bpj.2019.06.025 Learn more
Summary

Protein-mediated membrane remodeling is a ubiquitous and critical process for proper cellular function. Inverse Bin/Amphiphysin/Rvs (I-BAR) domains drive local membrane deformation as a precursor to large-scale membrane remodeling. We employ a multiscale approach to provide the molecular mechanism of unusual I-BAR domain-driven membrane remodeling at a low protein surface concentration with near-atomistic detail. We generate a bottom-up coarse-grained model that demonstrates similar membrane-bound I-BAR domain aggregation behavior as our recent Mesoscopic Membrane with Explicit Proteins model. Together, these models bridge several length scales and reveal an aggregation behavior of I-BAR domains. We find that at low surface coverage (i.e., low bound protein density), I-BAR domains form transient, tip-to-tip strings on periodic flat membrane sheets. Inside of lipid bilayer tubules, we find linear aggregates parallel to the axis of the tubule. Finally, we find that I-BAR domains form tip-to-tip aggregates around the edges of membrane domes. These results are supported by in vitro experiments showing low curvature bulges surrounded by I-BAR domains on giant unilamellar vesicles. Overall, our models reveal new I-BAR domain aggregation behavior in membrane tubules and on the surface of vesicles at low surface concentration that add insight into how I-BAR domain proteins may contribute to certain aspects of membrane remodeling in cells.

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Mathieu Richard, Carles Blanch-Mercader, Hajer Ennomani, Wenxiang Cao, Enrique M De La Cruz, Jean-François Joanny, Frank Jülicher, Laurent Blanchoin, Pascal Martin (2019 Jul 11)

Active cargo positioning in antiparallel transport networks.

Proceedings of the National Academy of Sciences of the United States of America : DOI : 10.1073/pnas.1900416116 Learn more
Summary

Cytoskeletal filaments assemble into dense parallel, antiparallel, or disordered networks, providing a complex environment for active cargo transport and positioning by molecular motors. The interplay between the network architecture and intrinsic motor properties clearly affects transport properties but remains poorly understood. Here, by using surface micropatterns of actin polymerization, we investigate stochastic transport properties of colloidal beads in antiparallel networks of overlapping actin filaments. We found that 200-nm beads coated with myosin Va motors displayed directed movements toward positions where the net polarity of the actin network vanished, accumulating there. The bead distribution was dictated by the spatial profiles of local bead velocity and diffusion coefficient, indicating that a diffusion-drift process was at work. Remarkably, beads coated with heavy-mero-myosin II motors showed a similar behavior. However, although velocity gradients were steeper with myosin II, the much larger bead diffusion observed with this motor resulted in less precise positioning. Our observations are well described by a 3-state model, in which active beads locally sense the net polarity of the network by frequently detaching from and reattaching to the filaments. A stochastic sequence of processive runs and diffusive searches results in a biased random walk. The precision of bead positioning is set by the gradient of net actin polarity in the network and by the run length of the cargo in an attached state. Our results unveiled physical rules for cargo transport and positioning in networks of mixed polarity.

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Nicola de Franceschi, Maryam Alqabandi, Winfried Weissenhorn, Patricia Bassereau (2019 Jul 5)

Dynamic and Sequential Protein Reconstitution on Negatively Curved Membranes by Giant Vesicles Fusion.

Bio-Protocol : 9 : e3294 : DOI : 10.21769/BioProtoc.3294 Learn more
Summary

In vitro investigation of the interaction between proteins and positively curved membranes can be performed using a classic nanotube pulling method. However, characterizing protein interaction with negatively curved membranes still represents a formidable challenge. Here, we describe our recently developed approach based on laser-triggered Giant Unilamellar Vesicles (GUVs) fusion. Our protocol allows sequential addition of proteins to a negatively curved membrane, while at the same time controlling the buffer composition, lipid composition and membrane tension. Moreover, this method does not require a step of protein detachment, greatly simplifying the process of protein encapsulation over existing methods.

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Elena Beltrán-Heredia, Feng-Ching Tsai, Samuel Salinas-Almaguer, Francisco J. Cao*, Patricia Bassereau*, Francisco Monroy* (2019 Jun 20)

Membrane curvature induces cardiolipin sorting.

Communications Biology : 2 : 225 : DOI : 10.1038/s42003-019-0471-x Learn more
Summary

Cardiolipin is a cone-shaped lipid predominantly localized in curved membrane sites of bacteria and in the mitochondrial cristae. This specific localization has been argued to be geometry-driven, since the CL’s conical shape relaxes curvature frustration. Although previous evidence suggests a coupling between CL concentration and membrane shape in vivo, no precise experimental data are available for curvature-based CL sorting in vitro. Here, we test this hypothesis in experiments that isolate the effects of membrane curvature in lipid-bilayer nanotubes. CL sorting is observed with increasing tube curvature, reaching a maximum at optimal CL concentrations, a fact compatible with self-associative clustering. Observations are compatible with a model of membrane elasticity including van der Waals entropy, from which a negative intrinsic curvature of -1.1 nm-1 is predicted for CL. The results contribute to understanding the physicochemical interplay between membrane curvature and composition, providing key insights into mitochondrial and bacterial membrane organization and dynamics.

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Katz M, Corson F*, Keil W*, Singhal A, Bae A, Lu Y, Liang Y & Shaham S (2019 Apr 23)

Glutamate spillover in C. elegans triggers repetitive behavior through presynaptic activation of MGL-2/mGluR5

Nature Communications : 10 : DOI : 10.1038/s41467-019-09581-4 Learn more
Summary

Glutamate is a major excitatory neurotransmitter, and impaired glutamate clearance following synaptic release promotes spillover, inducing extra-synaptic signaling. The effects of glutamate spillover on animal behavior and its neural correlates are poorly understood. We developed a glutamate spillover model in Caenorhabditis elegans by inactivating the conserved glial glutamate transporter GLT-1. GLT-1 loss drives aberrant repetitive locomotory reversal behavior through uncontrolled oscillatory release of glutamate onto AVA, a major interneuron governing reversals. Repetitive glutamate release and reversal behavior require the glutamate receptor MGL-2/mGluR5, expressed in RIM and other interneurons presynaptic to AVA. mgl-2 loss blocks oscillations and repetitive behavior; while RIM activation is sufficient to induce repetitive reversals in glt-1 mutants. Repetitive AVA firing and reversals require EGL-30/Gαq, an mGluR5 effector. Our studies reveal that cyclic autocrine presynaptic activation drives repetitive reversals following glutamate spillover. That mammalian GLT1 and mGluR5 are implicated in pathological motor repetition suggests a common mechanism controlling repetitive behaviors.

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Mélanie Tobin, Atitheb Chaiyasitdhi, Vincent Michel, Nicolas Michalski, Pascal Martin (2019 Apr 2)

Stiffness and tension gradients of the hair cell’s tip-link complex in the mammalian cochlea.

eLife : DOI : 10.7554/eLife.43473 Learn more
Summary

Sound analysis by the cochlea relies on frequency tuning of mechanosensory hair cells along a tonotopic axis. To clarify the underlying biophysical mechanism, we have investigated the micromechanical properties of the hair cell’s mechanoreceptive hair bundle within the apical half of the rat cochlea. We studied both inner and outer hair cells, which send nervous signals to the brain and amplify cochlear vibrations, respectively. We find that tonotopy is associated with gradients of stiffness and resting mechanical tension, with steeper gradients for outer hair cells, emphasizing the division of labor between the two hair-cell types. We demonstrate that tension in the tip links that convey force to the mechano-electrical transduction channels increases at reduced Ca. Finally, we reveal gradients in stiffness and tension at the level of a single tip link. We conclude that mechanical gradients of the tip-link complex may help specify the characteristic frequency of the hair cell.

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Joanna Podkalicka, Patricia Bassereau (2019 Apr 1)

How membrane physics rules the HIV envelope.

Nature Cell Biology : 21 : 413–415 : DOI : 10.1038/s41556-019-0312-7 Learn more
Summary

HIV particles incorporate host membrane proteins into their envelope to evade the immune system and infect other cells. A study now shows that Gag assembly on the host cell membrane produces a raft-like nanodomain favourable for protein partitioning due to a transbilayer coupling mechanism assisted by long saturated chain lipids and cholesterol.

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Jamecna D, Polidori DJ, Mesmin B, Dezi M, Lévy D, Bigay J, Antonny B (2019 Mar 22)

An intrinsically disordered region in OSBP acts as an entropic barrier to control protein dynamics and orientation at membrane contact sites

Developmental cell * : * highlighted Trend in Cell Biology 2019 : DOI : 10.1016/j.devcel.2019.02.021 Learn more
Summary

Lipid transfer proteins (LTPs) acting at membrane contact sites (MCS) between the ER and other organelles contain domains involved in heterotypic (e.g. ER to Golgi) membrane tethering as well as domains involved in lipid transfer. Here, we show that a long ≈ 90 aa intrinsically unfolded sequence at the N-terminus of oxysterol binding protein (OSBP) controls OSBP orientation and dynamics at MCS. This Gly-Pro-Ala-rich sequence, whose hydrodynamic radius is twice as that of folded domains, prevents the two PH domains of the OSBP dimer from homotypically tethering two Golgi-like membranes and considerably facilitates OSBP in-plane diffusion and recycling at MCS. Although quite distant in sequence, the N-terminus of OSBP-related protein-4 (ORP4) has similar effects. We propose that N-terminal sequences of low complexity in ORPs form an entropic barrier that restrains protein orientation, limits protein density and facilitates protein mobility in the narrow and crowded MCS environment.

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Simon C*, Kusters R*, Caorsi V*, Allard A, Abou-Ghali M, Manzi J, Di Cicco A, Lévy D, Lenz M, Joanny J-F, Campillo C, Plastino J, Sens P*, Sykes C* (2019 Mar 18)

Actin dynamics drive cell-like membrane deformation

Nature Physics : DOI : 10.1038/s41567-019-0464-1 Learn more
Summary

Cell membrane deformations are crucial for proper cell function. Specialized protein assemblies initiate inward or outward membrane deformations that the cell uses respectively to uptake external substances or probe the environment. The assembly and dynamics of the actin cytoskeleton are involved in this process, although their detailed role remains controversial. We show here that a dynamic, branched actin network is sufficient to initiate both inward and outward membrane deformation. The polymerization of a dense actin network at the membrane of liposomes produces inward membrane bending at low tension, while outward deformations are robustly generated regardless of tension. Our results shed light on the mechanism cells use to internalize material, both in mammalian cells, where actin polymerization forces are required when membrane tension is increased, and in yeast, where those forces are necessary to overcome the opposing turgor pressure. By combining experimental observations with physical modelling, we propose a mechanism that explains how membrane tension and the architecture of the actin network regulate cell-like membrane deformations.

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Bertin Aurélie, Lomakin Alexis (2019 Feb 15)

Meeting report – Building the Cell 2018

journal of cell science : 132 : DOI : 10.1242/jcs.229765 Learn more
Summary

Cell biologists from all around the world gathered in Paris on the 26 to 28 September 2018 to participate in the 3rd international meeting ‘Building the Cell’. It was organized by Hélène Barelli, Arnaud Echard, Thierry Galli, Florence Niedergang, Manuel Théry and Marie Hélène Verlhac on behalf of the French Society for Cell Biology (SBCF) at the Institut Pasteur. Around 230 participants joined the meeting for stimulating talks, discussions, poster sessions, and a gala dinner on the Seine that included a music performance by the rock group ‘Membrane Band’. The unifying theme of the meeting was the development of creative multidisciplinary approaches to understand cellular life at different scales in a dynamic and quantitative manner. Here, we summarize the results presented at the meeting and the emerging ideas from the different sessions.

The 3rd international meeting ‘Building the Cell’ (Fig. 1Fig. 2) was divided into ten different sessions that covered a variety of topics including intracellular trafficking, cell division, cytoskeletal dynamics and cell mechanics, cancer and stem cell biology, embryonic development and tissue morphogenesis, neurobiology, and aggregates and phase transitions. A broad spectrum of modern approaches and experimental systems ranging from synthetic biology and stem cell technologies to 3D organoids and animal models was presented. The meeting highlighted some of the latest and novel findings in cell biology, often coupled to major methodological developments in quantitative microscopy and computational modelling, as well as cell and tissue micro-engineering.

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