The acidic regions of WASp and N-WASP can synergize with CDC42Hs and Rac1 to induce filopodia and lamellipodia.
The acidic (A) region of WASp family proteins is thought to represent a high-affinity binding site for Arp2/3 complex without activating properties. Here we show that GST-fused WASp-A and N-WASP-A, but not a WASP-A/W500S mutant, several truncated WASp-A constructs or WAVE1-A can pull down Arp2/3 complex from cell lysates. Significantly, WASp-A and N-WASP-A synergistically trigger formation of filopodia or lamellipodia when coinjected with sub-effective concentrations of V12CDC42Hs or V12Rac1, respectively, into macrophages. The ability of WASp family A region constructs to induce this effect is closely correlated with their ability to bind Arp2/3 complex in vitro. These results imply that (i) Arp2/3 complex is critically involved in filopodia and lamellipodia formation in macrophages and (ii) acidic regions of WASp and N-WASP are not simply binding sites for Arp2/3 complex but can prime it for RhoGTPase-triggered signals leading to actin nucleation.
Hüfner
Katharina
K
Institut für Prophylaxe und Epidemiologie der Kreislaufkrankheiten, Ludwig-Maximilians-Universität, Pettenkoferstrasse 9, 80336 Munich, Germany.
Schell
Barbara
B
Aepfelbacher
Martin
M
Linder
Stefan
S
D051377:Actin-Related Protein 2; D051378:Actin-Related Protein 3; D000199:Actins / Q000378:metabolism; D002478:Cells, Cultured; D018844:Cyclin-Dependent Kinases / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D003598:Cytoskeletal Proteins; D005454:Fluorescence Polarization; D005982:Glutathione Transferase / Q000235:genetics; D006801:Humans; D046911:Macromolecular Substances; D008264:Macrophages / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D008840:Microfilament Proteins / Q000235:genetics / Q000378:metabolism; D008845:Microinjections; D008856:Microscopy, Fluorescence; D016297:Mutagenesis, Site-Directed; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D011485:Protein Binding / Q000502:physiology; D011506:Proteins / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D011554:Pseudopodia / Q000187:drug effects / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000008:administration & dosage / Q000235:genetics / Q000378:metabolism; D051316:Wiskott-Aldrich Syndrome Protein; D051300:Wiskott-Aldrich Syndrome Protein Family; D051317:Wiskott-Aldrich Syndrome Protein, Neuronal; D020830:rac1 GTP-Binding Protein / Q000378:metabolism* / Q000494:pharmacology
C495926:ACTR2 protein, human; C495928:ACTR3 protein, human; D051377:Actin-Related Protein 2; D051378:Actin-Related Protein 3; D000199:Actins; D003598:Cytoskeletal Proteins; D046911:Macromolecular Substances; D008840:Microfilament Proteins; D009419:Nerve Tissue Proteins; D011506:Proteins; D011993:Recombinant Fusion Proteins; C495767:WAS protein, human; C495771:WASL protein, human; D051316:Wiskott-Aldrich Syndrome Protein; D051300:Wiskott-Aldrich Syndrome Protein Family; D051317:Wiskott-Aldrich Syndrome Protein, Neuronal; D005982:Glutathione Transferase; D018844:Cyclin-Dependent Kinases; D020830:rac1 GTP-Binding Protein