A WAVE2-Abi1 complex mediates CSF-1-induced F-actin-rich membrane protrusions and migration in macrophages.
Colony-stimulating factor 1 (CSF-1) is an important physiological chemoattractant for macrophages. The mechanisms by which CSF-1 elicits the formation of filamentous actin (F-actin)-rich membrane protrusions and induces macrophage migration are not fully understood. In particular, very little is known regarding the contribution of the different members of the Wiskott-Aldrich Syndrome protein (WASP) family of actin regulators in response to CSF-1. Although a role for WASP itself in macrophage chemotaxis has been previously identified, no data was available regarding the function of WASP family verprolin-homologous (WAVE) proteins in this cell type. We found that WAVE2 was the predominant isoform to be expressed in primary macrophages and in cells derived from the murine monocyte/macrophage RAW264.7 cell line (RAW/LR5). CSF-1 treatment of macrophages resulted in WAVE2 accumulation in F-actin-rich protrusions induced by CSF-1. Inhibition of WAVE2 function by expressing a dominant-negative mutant or introducing anti-WAVE2 antibodies in RAW/LR5 cells, as well as reduction of endogenous WAVE2 expression by RNA-mediated interference (RNAi), resulted in a significant reduction of CSF-1-elicited F-actin protrusions. WAVE2 was found in a protein complex together with Abelson kinase interactor 1 (Abi1) in resting or stimulated cells. Both WAVE2 and Abi1 were recruited to and necessary for the formation of F-actin protrusions in response to CSF-1. Reducing the levels of WAVE2, directly or by targeting Abi1, resulted in an impaired cell migration to CSF-1. Altogether these data identify a WAVE2-Abi1 complex crucial for the normal actin cytoskeleton reorganization and migration of macrophages in response to CSF-1.
Kheir
Wassim Abou
WA
Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, New York City, NY 10461, USA.
Gevrey
Jean-Claude
JC
Yamaguchi
Hideki
H
Isaac
Beth
B
Cox
Dianne
D
D000199:Actins / Q000378:metabolism*; D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism*; D000818:Animals; D002465:Cell Movement / Q000187:drug effects / Q000502:physiology*; D003598:Cytoskeletal Proteins; D016173:Macrophage Colony-Stimulating Factor / Q000494:pharmacology*; D008264:Macrophages / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D051379:Mice; D046912:Multiprotein Complexes; D021381:Protein Transport; D011554:Pseudopodia / Q000187:drug effects* / Q000378:metabolism; D034622:RNA Interference; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051300:Wiskott-Aldrich Syndrome Protein Family / Q000378:metabolism*
C513734:Abi1 protein, mouse; D000199:Actins; D048868:Adaptor Proteins, Signal Transducing; D003598:Cytoskeletal Proteins; D046912:Multiprotein Complexes; D012333:RNA, Messenger; C492303:Wasf2 protein, mouse; D051300:Wiskott-Aldrich Syndrome Protein Family; D016173:Macrophage Colony-Stimulating Factor