Traction dynamics of filopodia on compliant substrates

Science. 2008 Dec 12;322(5908):1687-91. doi: 10.1126/science.1163595.


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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Actin Cytoskeleton / physiology*
  • Actins / physiology*
  • Animals
  • Biomechanical Phenomena
  • Cell Adhesion
  • Cells, Cultured
  • Chick Embryo
  • Compliance
  • Computer Simulation
  • Elastic Modulus
  • Elasticity
  • Growth Cones / physiology*
  • Growth Cones / ultrastructure
  • Models, Biological
  • Myosin Type II / physiology
  • Neurons / physiology
  • Pseudopodia / physiology*
  • Surface Tension


  • Actins
  • Myosin Type II