A new interaction between Abi-1 and betaPIX involved in PDGF-activated actin cytoskeleton reorganisation.
Members of the Rho family of GTPases are key regulators of the actin cytoskeleton. In particular, activated Rac1 stimulates membrane dorsal ruffle formation in response to platelet-derived growth factor (PDGF). Abl-interactor (Abi)-1 and betaPIX, a guanine nucleotide exchange factor for Rac1, localise at these Rac1-induced actin structures and play important roles in the induction of membrane dorsal ruffling in response to PDGF in fibroblasts. Here, we demonstrate a novel interaction between Abi-1 and betaPIX using the yeast two-hybrid system, in vitro pull-down assays, and in vivo co-immunoprecipitation experiments. In vitro, the C-terminal fragment of betaPIX interacted with Abi-1, while in vivo the N-terminal fragment of betaPIX interacted with Abi-1. The biological function of this interaction was investigated in mouse fibroblasts in response to PDGF stimulation. Abi-1 and betaPIX co-localised in the cytoplasm and to membrane dorsal ruffles after PDGF treatment. We show that the co-expression of Abi-1 and truncated forms of betaPIX in mouse fibroblasts blocked PDGF-induced membrane dorsal ruffles. Together, these results show that the interaction between Abi-1 and betaPIX is involved in the formation of growth factor-induced membrane dorsal ruffles.
Campa
Fanny
F
Max Planck Institute for Infection Biology, Department of Molecular Biology, Campus Charité Mitte, Berlin, Germany.
Machuy
Nikolaus
N
Klein
Alexander
A
Rudel
Thomas
T
D000199:Actins / Q000378:metabolism*; D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D021961:Cell Membrane Structures / Q000378:metabolism / Q000648:ultrastructure; D003598:Cytoskeletal Proteins / Q000235:genetics / Q000378:metabolism*; D003599:Cytoskeleton / Q000378:metabolism*; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism; D020662:Guanine Nucleotide Exchange Factors / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D041681:NIH 3T3 Cells; D010982:Platelet-Derived Growth Factor / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D064067:Rho Guanine Nucleotide Exchange Factors; D020798:Two-Hybrid System Techniques
C513734:Abi1 protein, mouse; D000199:Actins; D048868:Adaptor Proteins, Signal Transducing; C576607:Arhgef7 protein, mouse; D018797:Cell Cycle Proteins; D003598:Cytoskeletal Proteins; D020662:Guanine Nucleotide Exchange Factors; D010982:Platelet-Derived Growth Factor; D011993:Recombinant Fusion Proteins; D064067:Rho Guanine Nucleotide Exchange Factors