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H 1 Cell-like membranes are shaped by actin dynamics:
a biometric approach to study cell functions

Auteurs : Sykes, Cécile (Auteur de la Conférence)
CIRM (Editeur )

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    Résumé : The detailed mechanisms of many cell functions such as motility, traffic, division or filopodia formation is difficult to address due to cell complexity. In all these functions, a common observation is that cytoskeleton assembly correlates with membrane deformation based on active forces. The exact role, in particular, of the actin cytoskeleton in cell membrane deformation, with pushing or pulling forces is what we address here experimentally. We conceive stripped-down experimental systems that reproduce cellular behaviours in simplified conditions: cytoskeleton dynamics are reproduced on liposome membranes. Inspired by how actin forces can exert forces on membranes and organelles, we address now how the nucleus, which is the most rigid cell organelle, is deformed by the actin cytoskeleton during cell translocation.
    Actin polymerization through the growth of a branched actin network is able to initiate membrane tubules and spikes by pushing or pulling, which mimics the formation of endocytic vesicles and filopodia. By changing experimentally membrane tension and cytoskeleton structure, we displace the system within a phase diagram where inward or outward deformations are favoured. Moreover, shells of branched actin networks grown around liposomes display buckling and wrinkling under an osmotic deflation, thereby confirming their elastic properties. The time during which we let the network grow around liposomes allows us to vary the shell thickness, and to unveil the transition at which buckling or wrinkling occurs. Our results are in excellent agreement with the general mechanisms of buckling and wrinkling found in various systems spanning from pollen grains to the development of the gut or the brain.
    The role of actin on membrane trafficking is unveiled by using preformed membrane tubes and growing an actin network around them in a form of a sleeve. We show that actin is able to modulate the thickness of tubes maintained under force. In a cell, where membrane tubes are constantly pulled by motors walking on microtubules, we predict that actin provides a way of maintaining a variety of tube thicknesses.
    We study the translocation of the nucleus when cells move through narrow spaces that are smaller than their nuclei. We find that proteins of the nuclear membrane, such as nesprins, accumulate at the nucleus front during nucleus deformation and pull the nucleus forward.

    Codes MSC :
    37LXX - Infinite-dimensional dissipative dynamical systems
    74BXX - Elastic materials
    76Axx - Foundations, constitutive equations, rheology
    92Cxx - Physiological, cellular and medical topics

      Informations sur la Vidéo

      Réalisateur : Hennenfent, Guillaume
      Langue : Anglais
      Date de publication : 17/03/2020
      Date de captation : 25/02/2020
      Collection : Research talks ; Mathematical Physics ; Mathematics in Science and Technology
      Format : MP4
      Durée : 00:43:59
      Domaine : Mathematical Physics ; Mathematics in Science & Technology
      Audience : Chercheurs ; Doctorants , Post - Doctorants
      Download : https://videos.cirm-math.fr/2020-02-25_Sykes.mp4

    Informations sur la rencontre

    Nom de la rencontre : Thematic Month Week 4: Mathematics of Complex Systems in Biology and Medicine / Mois thématique Semaine 4 : Mathématiques des systèmes complexes en biologie et en médecine
    Organisateurs de la rencontre : Cristofol, Michel ; Freyermuth, Jean-Marc ; Gomez, Christophe ; Hubert, Florence ; Ryan, Shawn ; Tournus, Magali
    Dates : 24/02/2020 - 28/02/2020
    Année de la rencontre : 2020
    URL Congrès : https://conferences.cirm-math.fr/2304.html

    Citation Data

    DOI : 10.24350/CIRM.V.19616903
    Cite this video as: Sykes, Cécile (2020). Cell-like membranes are shaped by actin dynamics:
    a biometric approach to study cell functions. CIRM. Audiovisual resource. doi:10.24350/CIRM.V.19616903
    URI : http://dx.doi.org/10.24350/CIRM.V.19616903

    Voir aussi


    1. SIMON, Camille, KUSTERS, Rémy, CAORSI, Valentina, et al. Actin dynamics drive cell-like membrane deformation. Nature Physics, 2019, vol. 15, no 6, p. 602-609. - https://doi.org/10.1038/s41567-019-0464-1

    2. KUSTERS, Remy, SIMON, Camille, DOS SANTOS, Rogério Lopes, et al. Actin shells control buckling and wrinkling of biomembranes. Soft matter, 2019, vol. 15, no 47, p. 9647-9653. - https://doi.org/10.1039/C9SM01902B