Cortactin promotes and stabilizes Arp2/3-induced actin filament network formation

Abstract

Cortactin is a c-src substrate associated with sites of dynamic actin assembly at the leading edge of migrating cells. We previously showed that cortactin binds to Arp2/3 complex, the essential molecular machine for nucleating actin filament assembly. In this study, we demonstrate that cortactin activates Arp2/3 complex based on direct visualization of filament networks and pyrene actin assays. Strikingly, cortactin potently inhibited the debranching of filament networks. When cortactin was added in combination with the active VCA fragment of N-WASp, they synergistically enhanced Arp2/3-induced actin filament branching. The N-terminal acidic and F-actin binding domains of cortactin were both necessary to activate Arp2/3 complex. These results support a model in which cortactin modulates actin filament dendritic nucleation by two mechanisms, (1) direct activation of Arp2/3 complex and (2) stabilization of newly generated filament branch points. By these mechanisms, cortactin may promote the formation and stabilization of the actin network that drives protrusion at the leading edge of migrating cells.

Prostaglandins PGE2 and PGI2 promote endothelial barrier enhancement via PKA- and Epac1/Rap1-dependent Rac activation

“…Combined activation of Rac and Cdc42 leads to peripheral translocation of Rac/Cdc42 cytoskeletal effectors cortactin, Arp2/3, WAVE, Arc21, and N-WASP leading to enhancement of cortical actin cytoskeleton and increased width of intercellular adherens junctions essential for EC barrier maintenance [10,[60][61][62][63]. Activation of Rac/Cdc42 effector kinase PAK1 also contributes to activation of WAVE-Arp2/3 complex and initiates peripheral actin polymerization [62].…”

Spatial and temporal regulation of actin polymerization for cytoskeleton formation through Arp2/3 complex and WASP/WAVE proteins

“…1). The Arp2/3 complex functions not only as a nucleation core, it also associates with filaments by itself or with the aid of proteins such as WASP family proteins or cortactin [Marchand et al, 2001;Mullins et al, 1998;Suetsugu et al, 2001b;Uruno et al, 2001;Weaver et al, 2001]. Therefore, when the Arp2/3 complex is associated with pre-existing filaments, new filaments can form on preexisting filaments and generate an actin cytoskeleton immediately after the initiation of polymerization.…”

“…Endocytic vesicles also recruit N-WASP and form actin comets to move inside cells [Taunton et al, 2000]. Recently, proteins involved in endocytic vesicle transport, such as cortactin, Pan1p (yeast homolog of Eps15), and Abp1p, were found to associate with Arp2/3 complex [Duncan et al, 2001;Goode et al, 2001;Uruno et al, 2001;Weaver et al, 2001].…”

“…Cortactin associates with the sides of actin filaments and activates Arp2/3-mediated actin polymerization by promoting interaction of Arp2/3 complex with actin filaments [Uruno et al, 2001;Weaver et al, 2001]. N-WASP and WAVE2 also promote association of the Arp2/3 complex with actin filaments [Suetsugu et al, 2001b].…”

“…These molecules include cortactin, Pan1p, and Abp1p. They also associate with actin filaments [Duncan et al, 2001;Goode et al, 2001;Kessels et al, 2001;Suetsugu et al, 2001b;Uruno et al, 2001;Weaver et al, 2001]. Do these molecule enhances branches on filament?…”