UMR168 – Laboratoire Physico-Chimie Curie

Publications de l’UMR 168

Année de publication : 2019

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 En savoir plus
Résumé

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.

Replier
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 En savoir plus
Résumé

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.

Replier
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 En savoir plus
Résumé

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.

Replier
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 En savoir plus
Résumé

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.

Replier
Sarah Moitrier, Carles Blanch-Mercader, Simon Garcia, Kristina Sliogeryte,abc Tobias Martin, Jacques Camonis, Philippe Marcq, Pascal Silberzan and Isabelle Bonnet (2019 Feb 4)

Collective stresses drive competition between monolayers of normal and Ras-transformed cells

Soft Matter : 15 : DOI : 10.1039/C8SM01523F En savoir plus
Résumé

We study the competition for space between two cell lines that differ only in the expression of the Ras oncogene. The two cell populations are initially separated and set to migrate antagonistically towards an in-between stripe of free substrate. After contact, their interface moves towards the population of normal cells. We interpret the velocity and traction force data taken before and after contact thanks to a hydrodynamic description of collectively migrating cohesive cell sheets. The kinematics of cells, before and after contact, allows us to estimate the relative material parameters for both cell lines. As predicted by the model, the transformed cell population with larger collective stresses pushes the wild type cell population.

Replier

Année de publication : 2018

Cáceres R, Bojanala N, Kelley LC, Dreier J, Manzi J, Di Federico F, Chi Q, Risler T, Testa I, Sherwood DR, Plastino J (2018 Nov 6)

Forces drive basement membrane invasion in Caenorhabditis elegans

Proceedings of the National Academy of Sciences USA : 115 : 11537-11542 : DOI : 10.1073/pnas.1808760115 En savoir plus
Résumé

Replier
Vincent Nier, Grégoire Peyret, Joseph d'Alessandro, Shuji Ishihara, Benoit Ladoux, Philippe Marcq (2018 Oct 11)

Kalman Inversion Stress Microscopy.

Biophysical journal : DOI : S0006-3495(18)31065-8 En savoir plus
Résumé

Although mechanical cues are crucial to tissue morphogenesis and development, the tissue mechanical stress field remains poorly characterized. Given traction force time-lapse movies, as obtained by traction force microscopy of in vitro cellular sheets, we show that the tissue stress field can be estimated by Kalman filtering. After validation using numerical data, we apply Kalman inversion stress microscopy to experimental data. We combine the inferred stress field with velocity and cell-shape measurements to quantify the rheology of epithelial cell monolayers in physiological conditions, found to be close to that of an elastic and active material.

Replier
Duclos G., Blanch-Mercader C., Yashunsky V., Salbreux G., Joanny J.-F., Prost J., Silberzan P. (2018 Oct 3)

Spontaneous shear flow in confined cellular nematics

Nature Physics : DOI : 10.1038/s41567-018-0099-7 En savoir plus
Résumé

In embryonic development or tumour evolution, cells often migrate collectively within confining tracks defined by their microenvironment1,2. In some of these situations, the displacements within a cell strand are antiparallel3, giving rise to shear flows. However, the mechanisms underlying these spontaneous flows remain poorly understood. Here, we show that an ensemble of spindle-shaped cells plated in a well-defined stripe spontaneously develops a shear flow whose characteristics depend on the width of the stripe. On wide stripes, the cells self-organize in a nematic phase with a director at a well-defined angle with the stripe’s direction, and develop a shear flow close to the stripe’s edges. However, on stripes narrower than a critical width, the cells perfectly align with the stripe’s direction and the net flow vanishes. A hydrodynamic active gel theory provides an understanding of these observations and identifies the transition between the non-flowing phase oriented along the stripe and the tilted phase exhibiting shear flow as a Fréedericksz transition driven by the activity of the cells. This physical theory is grounded in the active nature of the cells and based on symmetries and conservation laws, providing a generic mechanism to interpret in vivo antiparallel cell displacements.

Replier
Plastino J, Blanchoin L (2018 Aug 13)

Dynamic stability of the actin ecosystem

Journal of Cell Science : 132 : pii: jcs219832 : DOI : 10.1242/jcs.219832 En savoir plus
Résumé

Replier
Camille Clément, Guillermo A Orsi, Alberto Gatto, Ekaterina Boyarchuk, Audrey Forest, Bassam Hajj, Judith Miné-Hattab, Mickaël Garnier, Zachary A Gurard-Levin, Jean-Pierre Quivy, Geneviève Almouzni (2018 Aug 9)

High-resolution visualization of H3 variants during replication reveals their controlled recycling

Nature communications : 9 : DOI : 10.1038/s41467-018-05697-1 En savoir plus
Résumé

DNA replication is a challenge for the faithful transmission of parental information to daughter cells, as both DNA and chromatin organization must be duplicated. Replication stress further complicates the safeguard of epigenome integrity. Here, we investigate the transmission of the histone variants H3.3 and H3.1 during replication. We follow their distribution relative to replication timing, first in the genome and, second, in 3D using super-resolution microscopy. We find that H3.3 and H3.1 mark early- and late-replicating chromatin, respectively. In the nucleus, H3.3 forms domains, which decrease in density throughout replication, while H3.1 domains increase in density. Hydroxyurea impairs local recycling of parental histones at replication sites. Similarly, depleting the histone chaperone ASF1 affects recycling, leading to an impaired histone variant landscape. We discuss how faithful transmission of histone variants involves ASF1 and can be impacted by replication stress, with ensuing consequences for cell fate and tumorigenesis.

Replier
Merle T, Farge E. (2018 Aug 1)

Trans-scale mechanotransductive cascade of biochemical and biomechanical patterning in embryonic development: the light side of the force.

Curr. Opin. Cell. Biol. : DOI : 10.1016/j.ceb.2018.07.003 En savoir plus
Résumé

Embryonic development is made of complex tissue shape changes and cell differentiation tissue patterning. Both types of morphogenetic processes, respectively biomechanical and biochemical in nature, were historically long considered as disconnected. Evidences of the biochemical patterning control of morphogenesis accumulated during the last 3 decades. Recently, new data revealed reversal mechanotransductive feedback demonstrating the strong coupling between embryonic biomechanical and biochemical patterning. Here we will review the findings of the emerging field of mechanotransduction in animal developmental biology and its most recent advancements. We will see how such mechanotransductive cascade of biochemical and mechanical patterning events ensures trans-scale direct cues of co-regulation of the microscopic biomolecular activities with the macroscopic morphological patterning. Mechanotransduction regulates many aspects of embryonic development including efficient collective cell behaviour, distant tissues morphogenesis coordination, and the robust coordination of tissue shape morphogenesis with differentiation.

Replier
Simon C, Caorsi V, Campillo C, Sykes C (2018 Jul 30)

Interplay between membrane tension and the actin cytoskeleton determines shape changes

Physical Biology : 5 : 065004 : DOI : 10.1088/1478-3975/aad1ab En savoir plus
Résumé

Replier
Röper Jens-Christian, Mitrossilis Démosthène, Stirnemann Guillaume, Waharte François, Brito Isabel, Fernandez-Sanchez Maria-Elena, Baaden Marc, Salamero Jean, Farge Emmanuel (2018 Jul 19)

The major β-catenin/E-cadherin junctional binding site is a primary molecular mechano-transductor of differentiation in vivo

eLIFE : 7:e33381. DOI: https://doi.org/10.7554/eLife.33381 : DOI : DOI: https://doi.org/10.7554/eLife.33381 En savoir plus
Résumé

In vivo, the primary molecular mechanotransductive events mechanically initiating cell differentiation remain unknown. Here we find the molecular stretching of the highly conserved Y654-beta-catenin-D665-E-cadherin binding site as mechanically induced by tissue strain. It triggers the increase of accessibility of the Y654 site, target of the Src42A kinase phosphorylation leading to irreversible unbinding. Molecular dynamics simulations of the beta-catenin/E-cadherin complex under a force mimicking a 6 pN physiological mechanical strain predict a local 45% stretching between the two a-helices linked by the site and a 15% increase in accessibility of the phosphorylation site. Both are quantitatively observed using FRET lifetime imaging and non-phospho Y654 specific antibody labelling, in response to the mechanical strains developed by endogenous and magnetically mimicked early mesoderm invagination of gastrulating Drosophila embryos. This is followed by the predicted release of 16% of beta-catenin from junctions, observed in FRAP, which initiates the mechanical activation of the b-catenin pathway process.

Replier
Duclos G., Deforet M., Yevick H.G., Cochet-Escartin O., Ascione F., Moitrier S., Sarkar T., Yashunsky V., Bonnet I., Buguin A., Silberzan P. (2018 Jun 11)

Controlling confinement and topology to study collective cell behaviors

Methods in Molecular Biology“Cell Migration: Methods and Protocols” : 1749 : 387-399 : DOI : 10.1007/978-1-4939-7701-7_28 En savoir plus
Résumé

Confinement and substrate topology strongly affect the behavior of cell populations and, in particular, their collective migration. In vitro experiments dealing with these aspects require strategies of surface patterning that remain effective over long times (typically several days) and ways to control the surface topology in three dimensions. Here, we describe protocols addressing these two aspects. High-resolution patterning of a robust cell-repellent coating is achieved by etching the coating through a photoresist mask patterned directly on the coated surface. Out-of-plane curvature can be controlled using glass wires or corrugated « wavy » surfaces.

Replier
Broders-Bondon Florence, Nguyen Ho-Bouldoires Thanh, Fernandez-Sanchez Maria Elena-Farge Emmanuel (2018 May 17)

Mechanotransduction in tumor progression: The dark side of the force.

Journal of Cell Biology : 217(5):1571-1587 : DOI : 10.1083/jcb.201701039 En savoir plus
Résumé

Cancer has been characterized as a genetic disease, associated with mutations that cause pathological alterations of the cell cycle, adhesion, or invasive motility. Recently, the importance of the anomalous mechanical properties of tumor tissues, which activate tumorigenic biochemical pathways, has become apparent. This mechanical induction in tumors appears to consist of the destabilization of adult tissue homeostasis as a result of the reactivation of embryonic developmental mechanosensitive pathways in response to pathological mechanical strains. These strains occur in many forms, for example, hypervascularization in late tumors leads to high static hydrodynamic pressure that can promote malignant progression through hypoxia or anomalous interstitial liquid and blood flow. The high stiffness of tumors directly induces the mechanical activation of biochemical pathways enhancing the cell cycle, epithelial–mesenchymal transition, and cell motility. Furthermore, increases in solid-stress pressure associated with cell hyperproliferation activate tumorigenic pathways in the healthy epithelial cells compressed by the neighboring tumor. The underlying molecular mechanisms of the translation of a mechanical signal into a tumor inducing biochemical signal are based on mechanically induced protein conformational changes that activate classical tumorigenic signaling pathways. Understanding these mechanisms will be important for the development of innovative treatments to target such mechanical anomalies in cancer.

Replier