Premium
Defects in cytokinesis, actin reorganization and the contractile vacuole in cells deficient in RhoGDI
Author(s) -
Rivero Francisco,
Illenberger Daria,
Somesh Baggavalli P.,
Dislich Heidrun,
Adam Nicola,
Meyer AnnKathrin
Publication year - 2002
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1093/emboj/cdf449
Subject(s) - biology , microbiology and biotechnology , actin , cytoskeleton , cytokinesis , vacuole , rac gtp binding proteins , gtpase , actin cytoskeleton , dictyostelium , rab , signal transduction , cell division , rac1 , biochemistry , cytoplasm , cell , gene
Rho GDP‐dissociation inhibitors (RhoGDIs) modulate the cycling of Rho GTPases between active GTP‐bound and inactive GDP‐bound states. We identified two RhoGDI homologues in Dictyostelium . GDI1 shares 51–58% similarity to RhoGDIs from diverse species. GDI2 is more divergent (40–44% similarity) and lacks the N‐terminal regulatory arm characteristic for RhoGDI proteins. Both are cytosolic proteins and do not relocalize upon reorganization of the actin cytoskeleton. Using a two‐hybrid approach, we identified Rac1a/1b/1c, RacB, RacC and RacE as interacting partners for GDI1. Cells lacking GDI1 are multinucleate, grow slowly and display a moderate pinocytosis defect, but rates of phagocytosis are unaffected. Mutant cells present prominent actin‐rich protrusions, and large vacuoles that are continuous with the contractile vacuole system. The actin polymerization response upon stimulation with cAMP was reduced, but the motile behavior toward the chemoattractant was unaffected. Our results indicate that GDI1 plays a central role in the regulation of signal transduction cascades mediated by Rho GTPases.