Islands of conformational stability for filopodia

Filopodia are long, thin protrusions formed when bundles of fibers grow outwardly from a cell surface while remaining closed in a membrane tube. We study the subtle issue of the mechanical stability of such filopodia and how this depends on the deformation of the membrane that arises when the fiber...

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Bibliographic Details
Published in:PloS one 2013-03, Vol.8 (3), p.e59010-e59010
Main Authors: Daniels, D Robert, Turner, Matthew S
Format: Article
Language:English
Subjects:
Algorithms
Biology
Biomechanical Phenomena
Bundling
Cell Membrane - physiology
Cell surface
Conformation
Crabs
Decapoda
Deformation
Deformation mechanisms
Energy
Euler buckling
Fibers
Filopodia
Holothurioidea
Limulus
Marine
Mathematical analysis
Mechanics
Membranes
Models, Biological
Physics
Polymers
Pseudopodia - physiology
Sperm
Stability
Steric effects
Thyone
Tubes
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Summary:Filopodia are long, thin protrusions formed when bundles of fibers grow outwardly from a cell surface while remaining closed in a membrane tube. We study the subtle issue of the mechanical stability of such filopodia and how this depends on the deformation of the membrane that arises when the fiber bundle adopts a helical configuration. We calculate the ground state conformation of such filopodia, taking into account the steric interaction between the membrane and the enclosed semiflexible fiber bundle. For typical filopodia we find that a minimum number of fibers is required for filopodium stability. Our calculation elucidates how experimentally observed filopodia can obviate the classical Euler buckling condition and remain stable up to several tens of μm. We briefly discuss how experimental observation of the results obtained in this work for the helical-like deformations of enclosing membrane tubes in filopodia could possibly be observed in the acrosomal reactions of the sea cucumber Thyone, and the horseshoe crab Limulus. Any realistic future theories for filopodium stability are likely to rely on an accurate treatment of such steric effects, as analysed in this work.
ISSN:1932-6203
1932-6203
DOI:10.1371/journal.pone.0059010