title: Strain hardening, avalanches, and strain softening in dense cross-linked actin networks.
abstract: Actin filament networks enable the cytoskeleton to adjust to internal and external forcing. These dynamic networks can adapt to changes by dynamically adjusting their cross-links. Here, we model actin filaments as cross-linked elastic fibers of finite dimensions, with the cross-links being approximately 1 mum apart, and employ a full three-dimensional model to study their elastic properties by computer simulations. The results show compelling evidence that dense actin networks are characterized by (a) strain hardening without entropic elasticity, (b) avalanches of cross-link slippage leading to strain softening in the case of breakable cross-links, and (c) spontaneous formation of stress fibers in the case of dynamic cross-link formation and destruction.
authors.affiliation: CSC-Finnish IT Center for Science, Esbo, Finland.
authors.forename: Jan A
authors.initials: JA
authors.lastname: Aström
authors.forename: P B Sunil
authors.initials: PB
authors.lastname: Kumar
authors.forename: Ilpo
authors.initials: I
authors.lastname: Vattulainen
authors.forename: Mikko
authors.initials: M
authors.lastname: Karttunen
mesh_terms: D000199:Actins / Q000737:chemistry* / Q000648:ultrastructure*; D001665:Binding Sites; D003198:Computer Simulation; D003432:Cross-Linking Reagents / Q000737:chemistry; D003599:Cytoskeleton / Q000737:chemistry* / Q000648:ultrastructure*; D004548:Elasticity; D006244:Hardness; D008956:Models, Chemical; D008958:Models, Molecular; D046912:Multiprotein Complexes / Q000737:chemistry / Q000648:ultrastructure; D011485:Protein Binding; D011487:Protein Conformation; D013314:Stress, Mechanical
chemical_list: D000199:Actins; D003432:Cross-Linking Reagents; D046912:Multiprotein Complexes