dictyNews
Electronic Edition
Volume 43, number 21
September 8, 2017

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

Differential functions of WAVE regulatory complex subunits in the 
regulation of actin-driven processes

Christof Litschko 1, Joern Linkner 1,2, Stefan Brühmann 1, Theresia 
Stradal 3, Tobias Reinl 4,5, Lothar Jänsch 4, Klemens Rottner 3,6, 
and Jan Faix 1

1 Institute for Biophysical Chemistry, Hannover Medical School, 
Carl-Neuberg-Str. 1, 30625 Hannover, Germany; 
2 present address: PerkinElmer LAS GmbH, Ferdinand-Porsche Ring 17, 
63110 Rodgau, Germany; 
3 Department of Cell Biology, Helmholtz Centre for Infection Research, 
Inhoffenstrasse 7, 38124 Braunschweig, Germany; 
4 Cellular Proteomics, Helmholtz Centre for Infection Research, 
Inhoffenstrasse 7, 38124 Braunschweig, Germany; 
5 present address: GlycoThera GmbH, Feodor-Lynen-Str. 35, 30625 
Hannover, Germany; 
6 Division of Molecular Cell Biology, Zoological Institute, Technische 
Universität Braunschweig, Spielmannstrasse 7, 38106 Braunschweig, 
Germany.


European Journal of Cell Biology, in press

The WAVE regulatory complex (WRC) links upstream Rho-family GTPase 
signaling to the activation of the ARP2/3 complex in different organisms. 
WRC-induced and ARP2/3 complex-mediated actin nucleation beneath 
the plasma membrane is critical for actin assembly in the leading edge to 
drive efficient cell migration. The WRC is a stable heteropentamer 
composed of SCAR/WAVE, Abi, Nap, Pir and the small polypeptide 
Brk1/Hspc300. Functional interference with individual subunits of the 
complex frequently results in diminished amounts of the remaining 
polypeptides of the WRC complex, implying the complex to act as 
molecular entity. However, Abi was also found to associate with mammalian 
N-WASP, formins, Eps8/SOS1 or VASP, indicating additional functions of 
individual WRC subunits in eukaryotic cells. To address this issue 
systematically, we inactivated all WRC subunits, either alone or in 
combination with VASP in Dictyostelium cells and quantified the protein 
content of the remaining subunits in respective WRC knockouts. The 
individual mutants displayed highly differential phenotypes concerning 
various parameters, including cell morphology, motility, cytokinesis or 
multicellular development, corroborating the view of additional roles for 
individual subunits, beyond their established function in WRC-mediated 
Arp2/3 complex activation. Finally, our data uncover the interaction of the 
actin polymerase VASP with WRC-embedded Abi to mediate VASP 
accumulation in cell protrusions, driving efficient cell migration.


submitted by: Jan Faix [faix.jan@mh-hannover.de]
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[End dictyNews, volume 43, number 21]