[Comp-neuro] new paper

[Arjen van Ooyen]

Janulevicius, A., Van Pelt, J., Van Ooyen, A. (2006) Compartment volume 
influences microtubule dynamic instability: a model study. Biophysical 
J. 90: 788-798.

For the full text of the paper, go to 
http://www.bio.vu.nl/enf/vanooyen/papers/microtubules_abstract.html

Abstract

Microtubules (MTs) are cytoskeletal polymers that exhibit dynamic 
instability, the random alternation between growth and shrinkage. MT 
dynamic instability plays an essential role in cell development, 
division and motility. To investigate dynamic instability, simulation 
models have been widely used. However, conditions under which the 
concentration of free tubulin fluctuates as a result of growing or 
shrinking MTs have not been studied before. Such conditions can arise, 
for example, in small compartments, such as neuronal growth cones. Here 
we investigate by means of computational modelling how concentration 
fluctuations caused by growing and shrinking MTs affect dynamic 
instability. We show that these fluctuations shorten MT growth and 
shrinkage times and change their distributions from exponential to 
non-exponential, gamma-like. Gamma-like distributions of MT growth and 
shrinkage times, which allow optimal stochastic searching by MTs, have 
been observed in various cell types and are believed to require 
structural changes in the MT during growth or shrinkage. Our results, 
however, show that these distributions can already arise as a result of 
fluctuations in the concentration of free tubulin due to growing and 
shrinking MTs. Such fluctuations are possible not only in small 
compartments but also when tubulin diffusion is slow or when many MTs 
(de)polymerize synchronously. Volume and all other factors that 
influence these fluctuations can affect MT dynamic instability and, 
consequently, the processes that depend on it, such as neuronal growth 
cone behaviour and cell motility in general.


-- 
Dr. Arjen van Ooyen
Center for Neurogenomics and Cognitive Research (CNCR)
Department of Experimental Neurophysiology
Vrije Universiteit
De Boelelaan 1085
1081 HV Amsterdam
The Netherlands

E-mail: arjen.van.ooyen at falw.vu.nl
Phone:  +31.20.5987090
Fax:    +31.20.5987112
Room:   C454
Web:    http://www.bio.vu.nl/enf/vanooyen