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Actin cross-linking proteins cortexillin I and II are required for cAMP signaling during Dictyostelium chemotaxis and development.

Authors
  • Shu, Shi
  • Liu, Xiong
  • Kriebel, Paul W
  • Daniels, Mathew P
  • Korn, Edward D
Type
Published Article
Journal
Molecular Biology of the Cell
Publisher
American Society for Cell Biology
Publication Date
Jan 01, 2012
Volume
23
Issue
2
Pages
390–400
Identifiers
DOI: 10.1091/mbc.E11-09-0764
PMID: 22114350
Source
Medline
License
Unknown

Abstract

Starvation induces Dictyostelium amoebae to secrete cAMP, toward which other amoebae stream, forming multicellular mounds that differentiate and develop into fruiting bodies containing spores. We find that the double deletion of cortexillin (ctx) I and II alters the actin cytoskeleton and substantially inhibits all molecular responses to extracellular cAMP. Synthesis of cAMP receptor and adenylyl cyclase A (ACA) is inhibited, and activation of ACA, RasC, and RasG, phosphorylation of extracellular signal regulated kinase 2, activation of TORC2, and stimulation of actin polymerization and myosin assembly are greatly reduced. As a consequence, cell streaming and development are completely blocked. Expression of ACA-yellow fluorescent protein in the ctxI/ctxII-null cells significantly rescues the wild-type phenotype, indicating that the primary chemotaxis and development defect is the inhibition of ACA synthesis and cAMP production. These results demonstrate the critical importance of a properly organized actin cytoskeleton for cAMP-signaling pathways, chemotaxis, and development in Dictyostelium.

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