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Mechanics and dynamics of actin-driven thin membrane protrusions
Erdinç Atilgan1, Denis Wirtz, Sean X Sun
1Department of Mechanical Engineering and the Whitaker Institute of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland, USA.
Biophysical Journal
|October 11, 2005
Summary
Cellular filopodia extend via actin filament growth, with flexible membranes enhancing speed. Filopodia dynamics are influenced by filament number, arrangement, and membrane interactions, leading to merging behaviors.
Area of Science:
- Cell Biology
- Biophysics
- Mechanobiology
Background:
- Motile cells utilize dynamic protrusions called filopodia for environmental exploration.
- Filopodia extension is driven by the polymerization of actin filament bundles beneath the plasma membrane.
Purpose of the Study:
- To compute the mechanical and dynamical features of filopodial growth.
- To investigate the role of the flexible plasma membrane in filopodia dynamics.
- To understand how filament arrangement and membrane interactions influence protrusion speed and behavior.
Main Methods:
- Computational modeling of actin filament bundles and flexible plasma membranes.
- Analysis of mechanical and dynamical properties of protrusion growth.
- Calculation of force-velocity relationships.
Main Results:
- A critical number of actin filaments are required for net filopodial growth.
- Flexible plasma membranes enhance protrusion speed through thermal fluctuations.
- Filopodia speed is dependent on filament number, spatial arrangement, and membrane tethering.
- Filopodia exhibit mutual attraction and merging due to membrane distortions.
Conclusions:
- The flexible plasma membrane significantly enhances filopodial protrusion speed.
- Filopodia dynamics are complex, governed by internal filament organization and external membrane interactions.
- Computational models can predict filopodia behavior, including merging and force-velocity relationships.