Skip to main content
Article thumbnail
Location of Repository

An Order of Magnitude Faster AIP1-Associated Actin Disruption than Nucleation by the Arp2/3 Complex in Lamellipodia

By Takahiro Tsuji, Takushi Miyoshi, Chiharu Higashida, Shuh Narumiya and Naoki Watanabe


The mechanism of lamellipod actin turnover is still under debate. To clarify the intracellular behavior of the recently-identified actin disruption mechanism, we examined kinetics of AIP1 using fluorescent single-molecule speckle microscopy. AIP1 is thought to cap cofilin-generated actin barbed ends. Here we demonstrate a reduction in actin-associated AIP1 in lamellipodia of cells overexpressing LIM-kinase. Moreover, actin-associated AIP1 was rapidly abolished by jasplakinolide, which concurrently blocked the F-actin-cofilin interaction. Jasplakinolide also slowed dissociation of AIP1, which is analogous to the effect of this drug on capping protein. These findings provide in vivo evidence of the association of AIP1 with barbed ends generated by cofilin-catalyzed filament disruption. Single-molecule observation found distribution of F-actin-associated AIP1 throughout lamellipodia, and revealed even faster dissociation of AIP1 than capping protein. The estimated overall AIP1-associated actin disruption rate, 1.8 µM/s, was one order of magnitude faster than Arp2/3 complex-catalyzed actin nucleation in lamellipodia. This rate does not suffice the filament severing rate predicted in our previous high frequency filament severing-annealing hypothesis. Our data together with recent biochemical studies imply barbed end-preferred frequent filament disruption. Frequent generation of AIP1-associated barbed ends and subsequent release of AIP1 may be the mechanism that facilitates previously observed ubiquitous actin polymerization throughout lamellipodia

Topics: Research Article
Publisher: Public Library of Science
OAI identifier:
Provided by: PubMed Central

Suggested articles


  1. (2004). A pathway of neuregulin-induced activation of cofilin-phosphatase Slingshot and cofilin in lamellipodia.
  2. (2000). Accumulation of GTP-bound RhoA during cytokinesis and a critical role of ECT2 in this accumulation.
  3. (2008). Actin disassembly by cofilin, coronin, and Aip1 occurs in bursts and is inhibited by barbed-end cappers.
  4. (2006). Actin filament branching and protrusion velocity in a simple 1D model of a motile cell.
  5. (2003). Actin filament disassembling activity of Caenorhabditis elegans actin-interacting protein 1 (UNC-78) is dependent on filament binding by a specific ADF/cofilin isoform.
  6. (1995). Actin filament organization in the fish keratocyte lamellipodium.
  7. (1991). Actin microfilament dynamics in locomoting cells.
  8. (2006). Actin turnover-dependent fast dissociation of capping protein in the dendritic nucleation actin network: evidence of frequent filament severing.
  9. (2005). Actindepolymerizing factor and cofilin-1 play overlapping roles in promoting rapid Factin depolymerization in mammalian nonmuscle cells.
  10. (1988). Actions of cytochalasins on the organization of actin filaments and microtubules in a neuronal growth cone.
  11. (2006). Aip1 and cofilin promote rapid turnover of yeast actin patches and cables: a coordinated mechanism for severing and capping filaments.
  12. (1999). Arp2/3 complex and actin depolymerizing factor/cofilin in dendritic organization and treadmilling of actin filament array in lamellipodia.
  13. (2008). Arp2/3 complex interactions and actin network turnover in lamellipodia.
  14. (2007). Biochemical and genetic analyses provide insight into the structural and mechanistic properties of actin filament disassembly by the Aip1p cofilin complex in Saccharomyces cerevisiae.
  15. (2003). Cellular motility driven by assembly and disassembly of actin filaments.
  16. (1998). Cofilin phosphorylation by LIM-kinase 1 and its role in Rac-mediated actin reorganization.
  17. (2004). Cofilin promotes actin polymerization and defines the direction of cell motility.
  18. (2007). Cofilin promotes stimulusinduced lamellipodium formation by generating an abundant supply of actin monomers.
  19. (1991). Control of actin polymerization in live and permeabilized fibroblasts.
  20. (1996). Dynamics of capping protein and actin assembly in vitro: uncapping barbed ends by polyphosphoinositides.
  21. (2004). End versus side branching by Arp2/ 3 complex.
  22. (2004). Evolution of new nonantibody proteins via iterative somatic hypermutation.
  23. (1985). Exchange of actin subunits at the leading edge of living fibroblasts: possible role of treadmilling.
  24. (2008). Gactin regulates rapid induction of actin nucleation by mDia1 to restore cellular actin polymers.
  25. (1998). How ADF/cofilin depolymerizes actin filaments.
  26. (1992). How Listeria exploits host cell actin to form its own cytoskeleton. I. Formation of a tail and how that tail might be involved in movement.
  27. (1999). Hyperosmotic stress-induced reorganization of actin bundles in Dictyostelium cells over-expressing cofilin.
  28. (1989). Incorporation and turnover of biotin-labeled actin microinjected into fibroblastic cells: an immunoelectron microscopic study.
  29. (1994). Interaction of Cap Z with actin. The NH2-terminal domains of the alpha 1 and beta subunits are not required for actin capping, and alpha 1 beta and alpha 2 beta heterodimers bind differentially to actin.
  30. (1995). Interpreting photoactivated fluorescence microscopy measurements of steady-state actin dynamics.
  31. (1994). Jasplakinolide, a cytotoxic natural product, induces actin polymerization and competitively inhibits the binding of phalloidin to F-actin.
  32. (2001). Kinetic mechanism of end-to-end annealing of actin filaments.
  33. (2008). Locomotor activity, ultrasonic vocalization and oxytocin levels in infant CD38 knockout mice.
  34. (2006). Mechanism of actin filament turnover by severing and nucleation at different concentrations of ADF/cofilin.
  35. (2004). Microscopic evidence that actin-interacting protein 1 actively disassembles actin-depolymerizing factor/cofilin-bound actin filaments.
  36. (1999). Proteins of the ADF/cofilin family: essential regulators of actin dynamics.
  37. (2006). Rapid actin monomerinsensitive depolymerization of Listeria actin comet tails by cofilin, coronin, and Aip1.
  38. (2003). Regulation of actin filament dynamics by actin depolymerizing factor/cofilin and actin-interacting protein 1: new blades for twisted filaments.
  39. (1999). Relationship between Arp2/3 complex and the barbed ends of actin filaments at the leading edge of carcinoma cells after epidermal growth factor stimulation.
  40. (2002). ROCK and mDia1 antagonize in Rho-dependent Rac activation in Swiss 3T3 fibroblasts.
  41. (2000). Role of cofilin in epidermal growth factor-stimulated actin polymerization and lamellipod protrusion.
  42. (2007). Self-organization of actin filament orientation in the dendritic-nucleation/array-treadmilling model.
  43. (2002). Single-Molecule Speckle Analysis of Actin Filament Turnover in Lamellipodia.
  44. (1999). The actin-based nanomachine at the leading edge of migrating cells.
  45. (2001). The Caenorhabditis elegans unc-78 gene encodes a homologue of actin-interacting protein 1 required for organized assembly of muscle actin filaments.
  46. (1998). The interaction of Arp2/3 complex with actin: nucleation, high affinity pointed end capping, and formation of branching networks of filaments.
  47. (1982). Tropomyosin binding to F-actin protects the F-actin from disassembly by brain actin-depolymerizing factor (ADF).
  48. (1999). Two activities of cofilin, severing and accelerating directional depolymerization of actin filaments, are affected differentially by mutations around the actin-binding helix.
  49. (2004). Two distinct actin networks drive the protrusion of migrating cells.
  50. (1999). XAIP1: a Xenopus homologue of yeast actin interacting protein 1 (AIP1), which induces disassembly of actin filaments cooperatively with ADF/cofilin family proteins.
  51. (2002). Xenopus actin-interacting protein 1 (XAip1) enhances cofilin fragmentation of filaments by capping filament ends.
  52. (1996). Xenopus laevis actindepolymerizing factor/cofilin: a phosphorylation-regulated protein essential for development.
  53. (1999). Yahara I

To submit an update or takedown request for this paper, please submit an Update/Correction/Removal Request.