title: Traction dynamics of filopodia on compliant substrates.
abstract: Cells sense the environment's mechanical stiffness to control their own shape, migration, and fate. To better understand stiffness sensing, we constructed a stochastic model of the "motor-clutch" force transmission system, where molecular clutches link F-actin to the substrate and mechanically resist myosin-driven F-actin retrograde flow. The model predicts two distinct regimes: (i) "frictional slippage," with fast retrograde flow and low traction forces on stiff substrates and (ii) oscillatory "load-and-fail" dynamics, with slower retrograde flow and higher traction forces on soft substrates. We experimentally confirmed these model predictions in embryonic chick forebrain neurons by measuring the nanoscale dynamics of single-growth-cone filopodia. Furthermore, we experimentally observed a model-predicted switch in F-actin dynamics around an elastic modulus of 1 kilopascal. Thus, a motor-clutch system inherently senses and responds to the mechanical stiffness of the local environment.
authors.affiliation: Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN 55455, USA.
authors.forename: Clarence E
authors.initials: CE
authors.lastname: Chan
authors.forename: David J
authors.initials: DJ
authors.lastname: Odde
mesh_terms: D008841:Actin Cytoskeleton / Q000502:physiology*; D000199:Actins / Q000502:physiology*; D000818:Animals; D001696:Biomechanical Phenomena; D002448:Cell Adhesion; D002478:Cells, Cultured; D002642:Chick Embryo; D003187:Compliance; D003198:Computer Simulation; D055119:Elastic Modulus; D004548:Elasticity; D020439:Growth Cones / Q000502:physiology* / Q000648:ultrastructure; D008954:Models, Biological; D024462:Myosin Type II / Q000502:physiology; D009474:Neurons / Q000502:physiology; D011554:Pseudopodia / Q000502:physiology*; D013500:Surface Tension
chemical_list: D000199:Actins; D024462:Myosin Type II