Regulation of focal adhesion formation by a vinculin-Arp2/3 hybrid complex.
Focal adhesions (FAs) are large multi-protein complexes that act as transmembrane links between the extracellular matrix and the actin cytoskeleton. Recently, FAs were extensively characterized, yet the molecular mechanisms underlying their mechanical and signalling functions remain unresolved. To address this question, we isolated protein complexes containing different FA components, from chicken smooth muscle, and characterized their properties. Here we identified 'hybrid complexes' consisting of the actin-nucleating subunits of Arp2/3 and either vinculin or vinculin and α-actinin. We further show that suppression of p41-ARC, a central component of native Arp2/3, which is absent from the hybrid complexes, increases the levels of the Arp2/3-nucleating core in FA sites and stimulates FA growth and dynamics. In contrast, overexpression of p41-ARC adversely affects FAs. These results support the view that Arp2/3 can form modular 'hybrid complexes' containing an actin-nucleating 'functional core', and 'anchoring domains' (vinculin/p41-ARC) that regulate its subcellular localization.
1] Department of Biological Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel [2] Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 76100, Israel.
Dror S
DS
Chorev
Department of Biological Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel.
Oren
O
Moscovitz
Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 76100, Israel.
Benjamin
B
Geiger
Department of Biological Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel.
Michal
M
Sharon
D051376:Actin-Related Protein 2-3 Complex / Q000235:genetics / Q000378:metabolism*; D000185:Actinin / Q000378:metabolism; D000818:Animals; D002645:Chickens; D016650:Fluorescein-5-isothiocyanate; D022001:Focal Adhesions / Q000502:physiology*; D006367:HeLa Cells; D006801:Humans; D007150:Immunohistochemistry; D047468:Immunoprecipitation; D013058:Mass Spectrometry; D008853:Microscopy; D009130:Muscle, Smooth / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics; D016596:Vinculin / Q000235:genetics / Q000378:metabolism*
D051376:Actin-Related Protein 2-3 Complex; D034741:RNA, Small Interfering; D000185:Actinin; D016596:Vinculin; D016650:Fluorescein-5-isothiocyanate