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

Please submit abstracts of your papers as soon as they have been
accepted for publication by sending them to [log in to unmask]
or by using the form at
http://dictybase.org/db/cgi-bin/dictyBase/abstract_submit.

Back issues of dictyNews, the Dicty Reference database and other
useful information is available at dictyBase - http://dictybase.org.

Follow dictyBase on twitter:
http://twitter.com/dictybase


=========
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 [[log in to unmask]]
==============================================================
[End dictyNews, volume 42, number 20]