title: Fiber networks amplify active stress.
abstract: Large-scale force generation is essential for biological functions such as cell motility, embryonic development, and muscle contraction. In these processes, forces generated at the molecular level by motor proteins are transmitted by disordered fiber networks, resulting in large-scale active stresses. Although these fiber networks are well characterized macroscopically, this stress generation by microscopic active units is not well understood. Here we theoretically study force transmission in these networks. We find that collective fiber buckling in the vicinity of a local active unit results in a rectification of stress towards strongly amplified isotropic contraction. This stress amplification is reinforced by the networks' disordered nature, but saturates for high densities of active units. Our predictions are quantitatively consistent with experiments on reconstituted tissues and actomyosin networks and shed light on the role of the network microstructure in shaping active stresses in cells and tissue.
authors.affiliation: Laboratoire de Physique Théorique et Modèles Statistiques (LPTMS), CNRS, Université Paris-Sud, Université Paris-Saclay, 91405 Orsay, France;
authors.forename: Pierre
authors.initials: P
authors.lastname: Ronceray
authors.affiliation: Arnold-Sommerfeld-Center for Theoretical Physics and Center for NanoScience, Ludwig-Maximilians-Universität München, D-80333 Munich, Germany; Lewis-Sigler Institute for Integrative Genomics and Joseph Henry Laboratories of Physics, Princeton University, Princeton, NJ 08544 martin.lenz@u-psud.fr c.broedersz@lmu.de.
authors.forename: Chase P
authors.initials: CP
authors.lastname: Broedersz
authors.affiliation: Laboratoire de Physique Théorique et Modèles Statistiques (LPTMS), CNRS, Université Paris-Sud, Université Paris-Saclay, 91405 Orsay, France; martin.lenz@u-psud.fr c.broedersz@lmu.de.
authors.forename: Martin
authors.identifier: http://orcid.org/0000-0002-2307-1106
authors.initials: M
authors.lastname: Lenz
mesh_terms: D008841:Actin Cytoskeleton / Q000737:chemistry / Q000502:physiology; D000205:Actomyosin / Q000737:chemistry; D001777:Blood Coagulation; D001792:Blood Platelets / Q000502:physiology; D003599:Cytoskeleton / Q000502:physiology; D004547:Elastic Tissue / Q000502:physiology*; D006801:Humans; D018625:Microscopy, Atomic Force; D008954:Models, Biological; D013312:Stress, Physiological
chemical_list: D000205:Actomyosin
keywords: biological tissues; cytoskeleton; fiber networks; soft active matter