Microtubules as Platforms for Assaying Actin Polymerization In Vivo

“…, 2008); EGFP-Lifeact (Riedl et al. , 2008); EGFP-fascin (Adams and Schwartz, 2000); EGFP-tagged cortactin, MBD-WWCA, and MBD-Spir-NT (Oelkers et al. , 2011); and pRK5mycRac1L61 and FMNL2ΔDAD (Block et al.…”

Section: Methodsmentioning

confidence: 99%

Arp2/3 complex is essential for actin network treadmilling as well as for targeting of capping protein and cofilin

Koestler

Steffen

Nemethova

et al. 2013

MBoC

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“…unpublished observation). The Arp2/3 complex in some systems was shown to be recruited to microtubules and plays a role in microtubule dynamics (Oelkers et al, 2011;Saedler et al, 2004). Given the facts that both actin and microtubule networks and their interactions are crucial for neurite outgrowth (Gordon-Weeks, 2004), it is possible that Arp2/3 complex-mediated growth cone formation plays a role in stabilizing microtubules in RGC processes.…”

Section: Discussionmentioning

confidence: 99%

Crucial Roles of the Arp2/3 Complex during Mammalian Corticogenesis

Wang

Chou

Guo

et al. 2015

Preprint

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The polarity and organization of radial glial cells (RGCs), which serve as both stem cells and scaffolds for neuronal migration, are crucial for cortical development. However, the cytoskeletal mechanisms that drive radial glial outgrowth and maintain RGC polarity remain poorly understood. Here, we show that the Arp2/3 complex -the unique actin nucleator that produces branched actin networks -plays essential roles in RGC polarity and morphogenesis. Disruption of the Arp2/3 complex in murine RGCs retards process outgrowth toward the basal surface and impairs apical polarity and adherens junctions. Whereas the former is correlated with an abnormal actin-based leading edge, the latter is consistent with blockage in membrane trafficking. These defects result in altered cell fate, disrupted cortical lamination and abnormal angiogenesis. In addition, we present evidence that the Arp2/3 complex is a cell-autonomous regulator of neuronal migration. Our data suggest that Arp2/3-mediated actin assembly might be particularly important for neuronal cell motility in a soft or poorly adhesive matrix environment.

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“…Cortactin functions in cellular structures have been predominantly attributed to its binding and activation of the Arp2/3 complex, which stimulates actin filament branching (16 -18), as well as its participation in Rho family GTPase signaling (11,19,20). The necessity of cortactin Arp2/3 complex activation in cell protrusion and motility depends on cellular context (21)(22)(23)(24), suggesting that cortactin has underappreciated, Arp2/3 complexindependent functions in actin-rich structures.…”

mentioning

confidence: 99%

Cortactin stabilization of actin requires actin-binding repeats and linker, is disrupted by specific substitutions, and is independent of nucleotide state

Scherer

Anand

Koleske

2018

Journal of Biological Chemistry

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The actin-binding protein cortactin promotes the formation and maintenance of actin-rich structures, including lamellipodial protrusions in fibroblasts and neuronal dendritic spines. Cortactin cellular functions have been attributed to its activation of the Arp2/3 complex, which stimulates actin branch nucleation, and to its recruitment of Rho family GTPase regulators. Cortactin also binds actin filaments and significantly slows filament depolymerization, but the mechanism by which it does so and the relationship between actin binding and stabilization are unclear. Here we elucidated the cortactin regions that are necessary and sufficient for actin filament binding and stabilization. Using actin cosedimentation assays, we found that the cortactin repeat region binds actin but that the adjacent linker region is required for binding with the same affinity as full-length cortactin. Using total internal reflection fluorescence microscopy to measure the rates of single filament actin depolymerization, we observed that cortactin-actin interactions are sufficient to stabilize actin filaments. Moreover, conserved charged residues in repeat 4 were necessary for high-affinity actin binding, and substitution of these residues significantly impaired cortactin-mediated actin stabilization. Cortactin bound actin with higher affinity than did its paralog, hematopoietic cell-specific Lyn substrate 1 (HS1), and the effects on actin stability were specific to cortactin. Finally, cortactin stabilized ADP-actin filaments, indicating that the stabilization mechanism does not depend on the actin nucleotide state. Together, these results indicate that cortactin binding to actin is necessary and sufficient to stabilize filaments in a concentration-dependent manner, specific to conserved residues in the cortactin repeats, and independent of the actin nucleotide state.

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Microtubules as Platforms for Assaying Actin Polymerization In Vivo

Cited by 10 publications

References 68 publications

Arp2/3 complex is essential for actin network treadmilling as well as for targeting of capping protein and cofilin

Arp2/3 complex is essential for actin network treadmilling as well as for targeting of capping protein and cofilin

Crucial Roles of the Arp2/3 Complex during Mammalian Corticogenesis

Cortactin stabilization of actin requires actin-binding repeats and linker, is disrupted by specific substitutions, and is independent of nucleotide state

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