The Rac1- and RhoG-specific GEF domain of Trio targets filamin to remodel cytoskeletal actin.
Rho GTPases control actin reorganization and many other cellular functions. Guanine nucleotide-exchange factors (GEFs) activate Rho GTPases by promoting their exchange of GDP for GTP. Trio is a unique Rho GEF, because it has separate GEF domains, GEFD1 and GEFD2, that control the GTPases RhoG/Rac1 and RhoA, respectively. Dbl-homology (DH) ... domains that are common to GEFs catalyse nucleotide exchange, and pleckstrin-homology (PH) domains localize Rho GEFs near their downstream targets. Here we show that Trio GEFD1 interacts through its PH domain with the actin-filament-crosslinking protein filamin, and localizes with endogenous filamin in HeLa cells. Trio GEFD1 induces actin-based ruffling in filamin-expressing, but not filamin-deficient, cells and in cells transfected with a filamin construct that lacks the Trio-binding domain. In addition, Trio GEFD1 exchange activity is not affected by filamin binding. Our results indicate that filamin, as a molecular target of Trio, may be a scaffold for the spatial organization of Rho-GTPase-mediated signalling pathways.
Mesh Terms:
Actins, Contractile Proteins, Cytoskeleton, GTP Phosphohydrolases, Guanine Nucleotide Exchange Factors, Hela Cells, Humans, Microfilament Proteins, Phosphoproteins, Protein Structure, Tertiary, Protein-Serine-Threonine Kinases, Signal Transduction, Transfection, rac1 GTP-Binding Protein, rho GTP-Binding Proteins
Actins, Contractile Proteins, Cytoskeleton, GTP Phosphohydrolases, Guanine Nucleotide Exchange Factors, Hela Cells, Humans, Microfilament Proteins, Phosphoproteins, Protein Structure, Tertiary, Protein-Serine-Threonine Kinases, Signal Transduction, Transfection, rac1 GTP-Binding Protein, rho GTP-Binding Proteins
Nat. Cell Biol.
Date: Dec. 01, 2000
PubMed ID: 11146652
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