Mesoscopic Model of Actin-Based Propulsion

Jie Zhu, Alex Mogilner

Research output: Contribution to journalArticle

24 Citations (Scopus)

Abstract

Two theoretical models dominate current understanding of actin-based propulsion: microscopic polymerization ratchet model predicts that growing and writhing actin filaments generate forces and movements, while macroscopic elastic propulsion model suggests that deformation and stress of growing actin gel are responsible for the propulsion. We examine both experimentally and computationally the 2D movement of ellipsoidal beads propelled by actin tails and show that neither of the two models can explain the observed bistability of the orientation of the beads. To explain the data, we develop a 2D hybrid mesoscopic model by reconciling these two models such that individual actin filaments undergoing nucleation, elongation, attachment, detachment and capping are embedded into the boundary of a node-spring viscoelastic network representing the macroscopic actin gel. Stochastic simulations of this 'in silico' actin network show that the combined effects of the macroscopic elastic deformation and microscopic ratchets can explain the observed bistable orientation of the actin-propelled ellipsoidal beads. To test the theory further, we analyze observed distribution of the curvatures of the trajectories and show that the hybrid model's predictions fit the data. Finally, we demonstrate that the model can explain both concave-up and concave-down force-velocity relations for growing actin networks depending on the characteristic time scale and network recoil. To summarize, we propose that both microscopic polymerization ratchets and macroscopic stresses of the deformable actin network are responsible for the force and movement generation.

Original languageEnglish (US)
Article numbere1002764
JournalPLoS Computational Biology
Volume8
Issue number11
DOIs
StatePublished - Nov 2012

Fingerprint

Actin
Propulsion
actin
Actins
Ratchet
microfilaments
Actin Cytoskeleton
polymerization
Polymerization
Model
Filament
Gels
gel
gels
capping
Elastic deformation
Computer Simulation
Elastic Deformation
Bistability
nucleation

ASJC Scopus subject areas

  • Cellular and Molecular Neuroscience
  • Ecology
  • Molecular Biology
  • Genetics
  • Ecology, Evolution, Behavior and Systematics
  • Modeling and Simulation
  • Computational Theory and Mathematics

Cite this

Mesoscopic Model of Actin-Based Propulsion. / Zhu, Jie; Mogilner, Alex.

In: PLoS Computational Biology, Vol. 8, No. 11, e1002764, 11.2012.

Research output: Contribution to journalArticle

Zhu, Jie ; Mogilner, Alex. / Mesoscopic Model of Actin-Based Propulsion. In: PLoS Computational Biology. 2012 ; Vol. 8, No. 11.
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