dictyNews Volume 17 Number 03

Published in

· 10 months ago

Dicty News 
Electronic Edition 
Volume 17, number 3 
August 3, 2001 

Please submit abstracts of your papers as soon as they have been 
accepted for publication by sending them to dicty@northwestern.edu. 

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

 
============== 
  Abstracts 
============== 
RasC is required for optimal activation of adenylyl cyclase and Akt/PKB  
during aggregation. 

Chinten James Lim, George B. Spiegelman, and Gerald Weeks. 

Department of Microbiology and Immunology, Department of Medical Genetics,  
University of British Columbia, Vancouver, British Columbia, V6T 1Z3 Canada. 

EMBO J., in press. 

ABSTRACT 

Disruption of Dictyostelium rasC, encoding a Ras subfamily protein,  
generated cells incapable of aggregation. While rasC expression is enriched  
in a cell type specific manner during post-aggregative development, the  
defect in rasC- cells is restricted to aggregation and fully corrected by  
application of exogenous cAMP pulses. cAMP is not produced in rasC- cells  
stimulated by 2'-deoxy-cAMP, but is produced in response to GTPgS in cell  
lysates, indicating that G-protein coupled cAMP receptor activation of  
adenylyl cyclase is regulated by RasC. However, cAMP induced ERK2  
phosphorylation is unaffected in rasC- cells, indicating RasC is not an  
upstream activator of the MAPK required for cAMP relay. rasC- cells also  
exhibit reduced chemotaxis to cAMP during early development and delayed  
response to periodic cAMP stimuli produced by wildtype cells in chimeric  
mixtures. Furthermore, cAMP induced Akt/PKB phosphorylation through a PI3K  
dependent pathway is dramatically reduced in rasC- cells, suggesting that  
G-protein coupled serpentine receptor activation of PI3K is regulated by  
RasC. Cells lacking the RasGEF, AleA, exhibit similar defects as rasC- cells,  
suggesting that AleA may activate RasC. 

 
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[End Dicty News, volume 17, number 3]