title: Cytoskeletal actin networks in motile cells are critically self-organized systems synchronized by mechanical interactions.
abstract: Growing networks of actin fibers are able to organize into compact, stiff two-dimensional structures inside lamellipodia of crawling cells. We put forward the hypothesis that the growing actin network is a critically self-organized system, in which long-range mechanical stresses arising from the interaction with the plasma membrane provide the selective pressure leading to organization. We show that a simple model based only on this principle reproduces the stochastic nature of lamellipodia protrusion (growth periods alternating with fast retractions) and several of the features observed in experiments: a growth velocity initially insensitive to the external force; the capability of the network to organize its orientation; a load-history-dependent growth velocity. Our model predicts that the spectrum of the time series of the height of a growing lamellipodium decays with the inverse of the frequency. This behavior is a well-known signature of self-organized criticality and is confirmed by unique optical tweezer measurements performed in vivo on neuronal growth cones.
authors.affiliation: SISSA, Via Bonomea 265, 34136 Trieste, Italy.
authors.forename: Luca
authors.initials: L
authors.lastname: Cardamone
authors.forename: Alessandro
authors.initials: A
authors.lastname: Laio
authors.forename: Vincent
authors.initials: V
authors.lastname: Torre
authors.forename: Rajesh
authors.initials: R
authors.lastname: Shahapure
authors.forename: Antonio
authors.initials: A
authors.lastname: DeSimone
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism; D000199:Actins / Q000378:metabolism*; D000818:Animals; D001696:Biomechanical Phenomena / Q000502:physiology; D002462:Cell Membrane / Q000378:metabolism; D002465:Cell Movement; D003198:Computer Simulation; D003599:Cytoskeleton / Q000378:metabolism*; D008954:Models, Biological; D009474:Neurons / Q000166:cytology* / Q000378:metabolism*; D051381:Rats; D013269:Stochastic Processes; D013312:Stress, Physiological
chemical_list: D000199:Actins