title: A new interaction between Abi-1 and betaPIX involved in PDGF-activated actin cytoskeleton reorganisation.
abstract: 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.
authors.affiliation: Max Planck Institute for Infection Biology, Department of Molecular Biology, Campus Charité Mitte, Berlin, Germany.
authors.forename: Fanny
authors.initials: F
authors.lastname: Campa
authors.forename: Nikolaus
authors.initials: N
authors.lastname: Machuy
authors.forename: Alexander
authors.initials: A
authors.lastname: Klein
authors.forename: Thomas
authors.initials: T
authors.lastname: Rudel
mesh_terms: 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
chemical_list: 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