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Purification of the Dendritic Filopodia-rich Fraction
Published on: May 2, 2019
On the mechanical stabilization of filopodia
Alexandra Zidovska1, Erich Sackmann
1Physics Department E22, Technical University Munich, Garching, Germany. alexandra_zidovska@hms.harvard.edu
Biophysical Journal
|March 16, 2011
Summary
We investigated how forces affect filopodia elongation using magnetic tweezers. Force-independent elongation and mechanical memory were observed, suggesting actin bundle dynamics play a key role.
Area of Science:
- Cell biology
- Biophysics
- Mechanobiology
Background:
- Filopodia are dynamic actin-rich cell protrusions crucial for cell migration and sensing.
- Understanding the mechanical properties of filopodia under force is essential for deciphering cellular processes.
Purpose of the Study:
- To investigate the force-induced elongation dynamics of filopodia.
- To characterize the viscoelastic properties and mechanical memory of filopodia.
Main Methods:
- Magnetic tweezers were used to apply controlled forces (20-600 pN) to filopodia tips via invasin.
- Force pulses and staircase-like force scenarios were applied to study filopodia response.
- Intracellular calcium levels were modulated using BAPTA, and actin polymerization was inhibited with latrunculin A.
Main Results:
- Filopodia exhibited a rapid viscoelastic deflection followed by a linear flow regime under force.
- Deflections were reversible, indicating mechanical memory.
- Elongation velocity was force-independent and showed an exponential distribution.
- BAPTA reduced elongation amplitude, while latrunculin A abolished the elastic response.
- Bending fluctuations allowed estimation of bending modulus and actin filament number.
Conclusions:
- Force-induced filopodia elongation is characterized by a force-independent velocity, suggesting a mechanism involving actin bundle elongation and membrane uncoupling.
- Reversibility of deformation points to treadmilling and elastic responses.
- Calcium ions and actin polymerization are critical for filopodia's mechanical behavior.
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