dictyNews
Electronic Edition
Volume 33, number 11
October 30, 2009

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=========
Abstracts
=========


Propagating waves separate two states of actin organization in living  
cells

Britta Schroth-Diez,1 Silke Gerwig,1 Mary Ecke,2 Reiner Hegerl,2
Stefan Diez,1 and Günther Gerisch2

1Max-Planck-Institut für Molekulare Zellbiologie und Genetik,
Pfotenhauerstrasse 108, D-01307 Dresden, Germany
2Max-Planck-Institut für Biochemie, Am Klopferspitz 18,
D-82152 Martinsried, Germany


HFSP Journal, in press [DOI: 10.2976/1.3239407]

Propagating actin waves are dynamic supramolecular structures formed  
by the
self-assembly of proteins within living cells. They are built from  
actin filaments
together with single-headed myosin, the Arp2/3 complex, and coronin in a
defined three-dimensional order. The function of these waves in  
structuring the
cell cortex is studied on the substrate-attached surface of  
Dictyostelium cells
by the use of total internal reflection fluorescence (TIRF)  
microscopy. Actin
waves separate two areas of the cell cortex from each other, which are
distinguished by the arrangement of actin filaments. The Arp2/3 complex
dominates in the area enclosed by a wave, where it has the capacity of
building dendritic structures, while the proteins prevailing in the  
external area,
cortexillin I and myosin-II, bundle actin filaments and arrange them in
antiparallel direction. Wave propagation is accompanied by transitions  
in the
state of actin with a preferential period of 5 min. Wave generation is  
preceded
by local fluctuations in actin assembly, some of the nuclei of  
polymerized actin
emanating from clathrin-coated structures, others emerging  
independently.
The dynamics of phase transitions has been analyzed to provide a basis  
for
modeling the nonlinear interactions that produce spatio-temporal  
patterns in
the actin system of living cells.

Submitted by Günther Gerisch [[log in to unmask]]
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[End dictyNews, volume 33, number 11]