Eur. Phys. J. E (2015) 38: 122
https://doi.org/10.1140/epje/i2015-15122-4

Regular Article

Theoretical study of actin layers attachment and separation

¹ Physico-Chimie Curie, (Institut Curie, Cnrs UMR 168, UPMC), Institut Curie Centre de Recherche, 26, rue de l’Ulm, 75005, Paris, France
² ICFP, Physics Department, Ecole Normale Supérieure de Paris, 24 rue Lhomond, 75005, Paris, France
³ ESPCI, 10 rue Vauquelin, 75005, Paris, France
⁴ Laboratory of Cell Physics, Institut de Science et d’Ingénierie Supramoléculaires, Institut de Génétique et de Biologie Moléculaire et Cellulaire, Université de Strasbourg and Centre National de la Recherche Scientifique UMR 7006, Strasbourg, France
⁵ Development and Stem Cells Program, Institut de Génétique et de Biologie Moléculaire et Cellulaire, Centre National de la Recherche Scientifique UMR 7104, Institut National de la Santé et de la Recherche Médicale (U964), Université de Strasbourg, Illkirch, France

^* e-mail: sophie@marbach.fr
^** e-mail: jean-francois.joanny@curie.fr

Received: 23 February 2015
Accepted: 3 November 2015
Published online: 25 November 2015

Abstract

We use the theory of active gels to study theoretically the merging and separation of two actin dense layers akin to cortical layers of animal cells. The layers bind at a distance equal to twice the thickness of a free layer, thus forming a single dense layer, similar in this sense to a lamellipodium. When that unique layer is stretched apart, it is resilient to break apart up to a critical length larger than twice the thickness of a free layer. We show that this behavior can result from the high contractile properties of the actomyosin gel due to the activity of myosin molecular motors. Furthermore, we establish that the stability of the stretched single layer is highly dependent on the properties of the gel. Indeed, the nematic order of the actin filaments along the polymerizing membranes is a destabilizing factor.