A probabilistic model for ligand-cytoskeleton transmembrane adhesion: predicting the behavior of microspheres on the surface of migrating cells.

OLIVIER THOUMINE, JEAN-JACQUES MEISTER
Journal of Theoretical Biology. 2000-06-01; 204(3): 381-392
DOI: 10.1006/jtbi.2000.2024

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1. J Theor Biol. 2000 Jun 7;204(3):381-92.

A probabilistic model for ligand-cytoskeleton transmembrane adhesion: predicting
the behavior of microspheres on the surface of migrating cells.

Thoumine O(1), Meister JJ.

Author information:
(1)Biomedical Engineering Laboratory, Swiss Federal Institute of Technology,
Lausanne, 1015, Switzerland.

A theoretical model describing the attachment and cytoskeletal coupling of
microspheres to the dorsal surface of motile cells was developed. Integral
membrane receptors beneath a ligand-coated microsphere are allowed to be either
free, attached to the microsphere, bound to the rearward moving actin network, or
linked to both the bead and the cytoskeleton, and to switch between these four
states. The binding transitions being modeled as chemical reactions governed by
rate constants taken from literature, the chance for a receptor to be in each
binding state over time is obtained by solving mass-balance equations for the
probability functions. The population of n such receptors beneath the microsphere
is accounted for by a binomial distribution for each state. Adhesion and
transmembrane coupling (resulting in microsphere transport) being defined by a
minimal number of ligand-receptor and receptor-cytoskeleton bonds, respectively,
the probabilities of attachment and transport of the microsphere over time are
expressed in terms of state probability distributions. It is found that
increasing the ligand density raises the attachment and transport probabilities,
in good quantitative agreement with recent experiments using optical tweezers and
accurate position tracking. Increasing the bead size does not affect attachment,
but raises the transport probability with a marked transition for bead diameter
around 100 nm, as for experimental data. Increasing the restraining force
decreases the transport probability, probably by inducing a rupture of
receptor-cytoskeleton bonds. This study thus provides a framework that helps
understand the process of cortical flow associated with cell locomotion.

Copyright 2000 Academic Press.

DOI: 10.1006/jtbi.2000.2024
PMID: 10816362 [Indexed for MEDLINE]

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