RRC ID 29069
Author Bosgraaf L, Waijer A, Engel R, Visser AJ, Wessels D, Soll D, van Haastert PJ.
Title RasGEF-containing proteins GbpC and GbpD have differential effects on cell polarity and chemotaxis in Dictyostelium.
Journal J Cell Sci
Abstract The regulation of cell polarity plays an important role in chemotaxis. Previously, two proteins termed GbpC and GbpD were identified in Dictyostelium, which contain RasGEF and cyclic nucleotide binding domains. Here we show that gbpC-null cells display strongly reduced chemotaxis, because they are unable to polarise effectively in a chemotactic gradient. However, gbpD-null mutants exhibit the opposite phenotype: cells display improved chemotaxis and appear hyperpolar, because cells make very few lateral pseudopodia, whereas the leading edge is continuously remodelled. Overexpression of GbpD protein results in severely reduced chemotaxis. Cells extend many bifurcated and lateral pseudopodia, resulting in the absence of a leading edge. Furthermore, cells are flat and adhesive owing to an increased number of substrate-attached pseudopodia. This GbpD phenotype is not dependent on intracellular cGMP or cAMP, like its mammalian homolog PDZ-GEF. Previously we showed that GbpC is a high-affinity cGMP-binding protein that acts via myosin II. We conclude that cGMP activates GbpC, mediating the chemoattractant-induced establishment of cell polarity through myosin. GbpD induces the formation of substrate-attached pseudopodia, resulting in increased attachment and suppression of polarity.
Volume 118(Pt 9)
Pages 1899-910
Published 2005-5-1
DOI 10.1242/jcs.02317
PII jcs.02317
PMID 15827084
MeSH Actins / chemistry Actins / metabolism Animals Carrier Proteins / biosynthesis* Carrier Proteins / physiology* Cell Adhesion Cell Membrane / metabolism Chemotaxis Cyclic AMP / metabolism Cyclic GMP / metabolism Dictyostelium / metabolism* Green Fluorescent Proteins / chemistry Green Fluorescent Proteins / metabolism Mutation Myosin Type II / chemistry Myosins / chemistry Phenotype Plasmids / metabolism Protein Binding Protein Structure, Tertiary Protein Transport Software Time Factors ras Guanine Nucleotide Exchange Factors / metabolism*
IF 4.573
Times Cited 43
Cellular slime molds S00008 S00010 S00143 S00338