dictyNews
Electronic Edition
Volume 39, number 6
March 1, 2013

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Abstracts
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A Dictyostelium secreted factor requires a PTEN-like phosphatase 
to slow proliferation and induce chemorepulsion

Sarah E. Herlihy, Yitai Tang, and Richard H. Gomer


PLoS ONE, in press

In Dictyostelium discoideum, AprA and CfaD are secreted proteins 
that inhibit cell proliferation. We found that the proliferation of cells 
lacking CnrN, a phosphatase and tensin homolog (PTEN)-like 
phosphatase, is not inhibited by exogenous AprA and is increased 
by exogenous CfaD. The expression of CnrN in cnrN¯ cells partially 
rescues these altered sensitivities, suggesting that CnrN is necessary 
for the ability of AprA and CfaD to inhibit proliferation. Cells lacking 
CnrN accumulate normal levels of AprA and CfaD. Like cells lacking 
AprA and CfaD, cnrN¯ cells proliferate faster and reach a higher 
maximum cell density than wild type cells, tend to be multinucleate, 
accumulate normal levels of mass and protein per nucleus, and form 
less viable spores. When cnrN¯ cells expressing myc-tagged CnrN 
are stimulated with a mixture of rAprA and rCfaD, levels of 
membrane-associated myc-CnrN increase. AprA also causes 
chemorepulsion of Dictyostelium cells, and CnrN is required for this 
process. Combined, these results suggest that CnrN functions in a 
signal transduction pathway downstream of AprA and CfaD 
mediating some, but not all, of the effects of AprA and CfaD.


Submitted by Richard Gomer [[log in to unmask]]
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The green tea catechin epigallocatechin gallate (EGCG) blocks cell 
motility, chemotaxis and development in Dictyostelium discoideum

Kyle J McQuade, Akihiko Nakajima, April N Ilacqua, Nao Shimada 
and Satoshi Sawai


PLOS ONE, in press

Catechins, flavanols found at high levels in green tea, have received 
significant attention due to their potential health benefits related to 
cancer, autoimmunity and metabolic disease, but little is known about 
the mechanisms by which these compounds affect cellular behavior. 
Here, we assess whether the model organism Dictyostelium discoideum 
is a useful tool with which to characterize the effects of catechins. 
Epigallocatechin gallate (EGCG), the most abundant and potent 
catechin in green tea, has significant effects on the Dictyostelium life 
cycle. In the presence of EGCG aggregation is delayed, cells do not 
stream and development is typically stalled at the loose aggregate 
stage. The developmental effects very likely result from defects in 
motility, as EGCG reduces both random movement and chemotaxis of 
Dictyostelium amoebae. These results suggest that catechins and 
their derivatives may be useful tools with which to better understand 
cell motility and development in Dictyostelium and that this organism 
is a useful model to further characterize the activities of catechins.
 
 
Submitted by Kyle McQuade [[log in to unmask]]
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[End dictyNews, volume 39, number 6]