Mehdi Bouzid (Laboratoire de Physique Théorique et Modèles Statistiques, Université Paris Sud, Orsay) Mechanical properties of fibre networks

Gels of brous biopolymers are ubiquitous within cells and their rigidity is crucial for their function [1]. Our current understanding of their elastic response is usually understood as an interplay between the bending and stretching of their filaments [2]. This point of view however fails when applied to the weakly coordinated branched actin networks found throughout the cell [3, 4]. Through experiments and theory, we show that their elasticity crucially involves reversible entanglements between their filaments. Additional entanglements may get locked in during network growth, setting the final properties of the network [5]. These properties could be key to understanding how moving cells dynamically adapt their cytoskeleton to their environment.

[1] G. Letort, H. Ennomani, L. Gressin, M. Thery, and L. Blanchoin, Dynamic reorganization of the actin cytoskeleton,"F1000Research, vol. 4, 2015.

[2] C. P. Broedersz, X. Mao, T. C. Lubensky, and F. C. MacKintosh, "Criticality and isostaticity in fibre networks,"Nature Physics, vol. 7, no. 12, p. 983, 2011.

[3] P. Bauer, J. Tavacoli, T. Pujol, J. Planade, J. Heuvingh, and O. Du Roure, "A new method to measure mechanics and dynamic assembly of branched actin networks," Scientic reports, vol. 7, no. 1, p. 15688, 2017.

[4] A. Allard, M. Bouzid, T. Betz, C. Simon, M. Abou-Ghali, J. Lemiere, F. Valentino, J. Manzi, F. Brochard-Wyart, K. Guevorkian, et al., "Actin modulates shape and mechanics of tubular membranes," bioRxiv, p. 712505, 2019.

[5] M. Bouzid, C. Valencia Gallardo, L. Koehler, G. Fo, J. Heuvingh, O. du Roure, and M. Lenz, "Elasticity from entanglements in branched actin," In preparation.