dictyNews Volume 42 Number 20

Published in

· 1 year ago

dictyNews 
Electronic Edition 
Volume 42, number 20 
September 2, 2016 

Please submit abstracts of your papers as soon as they have been 
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or by using the form at 
http://dictybase.org/db/cgi-bin/dictyBase/abstract_submit. 

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

 
Local Ras activation, PTEN pattern, and global actin flow in the  
chemotactic responses of over-sized cells 

 
Markus Lange, Jana Prassler, Mary Ecke, Annette Müller-Taubenberger,  
Günther Gerisch 

 
J Cell Sci, in press 

Chemotactic responses of eukaryotic cells require a signal processing  
system that translates an external gradient of attractant into directed  
motion. To challenge the response system to its limits, we increased  
the size of Dictyostelium disciodeum cells using electric-pulse induced  
fusion. Large cells formed multiple protrusions at different sites along  
the gradient of chemoattractant, which independently turned towards  
the gradient direction and competed with each other. Finally, these  
cells succeeded to re-establish polarity by coordinating front and tail  
activities. To analyze the responses, we combined two approaches, 
 one aimed at local responses by visualizing the dynamics of Ras  
activation at the front regions of re-orientating cells, the other at global  
changes of polarity by monitoringfront-to-tail directed actin flow.  
Asymmetric Ras activation in turning protrusions underscores that  
gradients can be sensed locally and translated into orientation.  
Different to cells of normal size, the polarity of large cells is not linked  
to an increasing front-to-tail gradient of the PIP3-phosphatase PTEN.  
But even in large cells, the front communicates with the tail through  
an actin flow that might act as carrier of a protrusion inhibitor. 

 
submitted by: Günther Gerisch [gerisch@biochem.mpg.de] 
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[End dictyNews, volume 42, number 20]