Dynamin2 GTPase and Cortactin Remodel Actin Filaments

Abstract

The large GTPase dynamin, best known for its activities that remodel membranes during endocytosis, also regulates F-actinrich structures, including podosomes, phagocytic cups, actin comet tails, subcortical ruffles, and stress fibers. The mechanisms by which dynamin regulates actin filaments are not known, but an emerging view is that dynamin influences F-actin via its interactions with proteins that interact directly or indirectly with actin filaments. We show here that dynamin2 GTPase activity remodels actin filaments in vitro via a mechanism that depends on the binding partner and F-actin-binding protein, cortactin. Tightly associated actin filaments crosslinked by dynamin2 and cortactin became loosely associated after GTP addition when viewed by transmission electron microscopy. Actin filaments were dynamically unraveled and fragmented after GTP addition when viewed in real time using total internal reflection fluorescence microscopy. Cortactin stimulated the intrinsic GTPase activity of dynamin2 and maintained a stable link between actin filaments and dynamin2, even in the presence of GTP. Filaments remodeled by dynamin2 GTPase in vitro exhibit enhanced sensitivity to severing by the actin depolymerizing factor, cofilin, suggesting that GTPase-dependent remodeling influences the interactions of actin regulatory proteins and F-actin. The global organization of the actomyosin cytoskeleton was perturbed in U2-OS cells depleted of dynamin2, implicating dynamin2 in remodeling actin filaments that comprise supramolecular F-actin arrays in vivo. We conclude that dynamin2 GTPase remodels actin filaments and plays a role in orchestrating the global actomyosin cytoskeleton.

Dynamin1 Is a Novel Target for IRSp53 Protein and Works with Mammalian Enabled (Mena) Protein and Eps8 to Regulate Filopodial Dynamics

“…In contrast, loss-of-function Dyn1K/E-GFP expression did not rescue lamellipodial formation and filopodial number. This further strengthens the idea that Dyn1 is involved in filopodial formation and that, in addition to the known role of GTPase domain in actin remodeling (42), the ABD is also required.…”

Etiological Role of Dynamin in Charcot-Marie-Tooth Disease

“…For example, interaction between dynamin 2 and cortactin, SH3-domain containing actin binding protein that binds also F-actin and actin-regulating Arp2/3 complex (Ammer & Weed, 2008), is associated with clathrin and dynamin-dependent endocytosis (Krueger et al, 2003;Cao et al, 2003;Zhu et al, 2005). On the other hand, however, the same dynamin-cortactin interaction is considered as a mechanism to recruit dynamin to the site of actin dynamics in other studies Schafer et al, 2002;Mooren et al, 2009;Yamada et al, 2009). Assembly and remodeling of actin filaments by dynamin 2, through an interaction with cortactin, has been investigated by in vitro experiments (Schafer et al, 2002;Mooren et al, 2009).…”

“…On the other hand, however, the same dynamin-cortactin interaction is considered as a mechanism to recruit dynamin to the site of actin dynamics in other studies Schafer et al, 2002;Mooren et al, 2009;Yamada et al, 2009). Assembly and remodeling of actin filaments by dynamin 2, through an interaction with cortactin, has been investigated by in vitro experiments (Schafer et al, 2002;Mooren et al, 2009). In their recent study, they demonstrated that, in the presence of dynamin, GTP led to remodeling of actin filaments in vitro via the actin-binding protein cortactin (Mooren et al, 2009).…”

“…In their recent study, they demonstrated that, in the presence of dynamin, GTP led to remodeling of actin filaments in vitro via the actin-binding protein cortactin (Mooren et al, 2009). As the mechanism of the actin regulation, they suggests that GTP hydrolysis-induced conformational change within dynamin is transduced to cortactin, which in turn alters orientation of the F-actin so that actin's sensitivity to cofilin, an actin depolymerizing factor, is increased (Mooren et al, 2009). However, as interactions between dynamin's PRD and cortactin's SH3 domain does not require GTP binding nor hydrolysis by dynamin, it remains uncertain how GTP hydrolysis dependent conformational change within dynamin might be transmitted to cortactin.…”

“…Assembly and remodeling of actin filaments by dynamin 2, through an interaction with cortactin, has been investigated by in vitro experiments (Schafer et al, 2002;Mooren et al, 2009). In their recent study, they demonstrated that, in the presence of dynamin, GTP led to remodeling of actin filaments in vitro via the actin-binding protein cortactin (Mooren et al, 2009). As the mechanism of the actin regulation, they suggests that GTP hydrolysis-induced conformational change within dynamin is transduced to cortactin, which in turn alters orientation of the F-actin so that actin's sensitivity to cofilin, an actin depolymerizing factor, is increased (Mooren et al, 2009).…”