Journal of Mathematical Biology

, Volume 63, Issue 2, pp 229–261

Modeling the formation of in vitro filopodia

Open Access


Filopodia are bundles of actin filaments that extend out ahead of the leading edge of a crawling cell to probe its upcoming environment. In vitro experiments (Vignjevic et al. in J Cell Biol 160:951–962, 2003) have determined the minimal ingredients required for the formation of filopodia from the dendritic-like morphology of the leading edge. We model these experiments using kinetic aggregation equations for the density of growing bundle tips. In mean field, we determine the bundle size distribution to be broad for bundle sizes smaller than a characteristic bundle size above which the distribution decays exponentially. Two-dimensional simulations incorporating both bundling and cross-linking measure a bundle size distribution that agrees qualitatively with mean field. The simulations also demonstrate a nonmonotonicity in the radial extent of the dendritic region as a function of capping protein concentration, as was observed in experiments, due to the interplay between percolation and the ratcheting of growing filaments off a spherical obstacle.


Nonequilibrium actin bundling Filopodia Kinetic aggregation 

Mathematics Subject Classification (2000)


Copyright information

© The Author(s) 2010

Authors and Affiliations

  1. 1.Department of MathematicsUniversity of California-DavisDavisUSA
  2. 2.Department of Neurobiology, Physiology and BehaviorUniversity of California-DavisDavisUSA
  3. 3.School of Natural SciencesUniversity of California-MercedMercedUSA
  4. 4.Physics DepartmentSyracuse UniversitySyracuseUSA

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