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Ena/VASP proteins interact directly with the WAVE complex

Chen, X.; (2011) Ena/VASP proteins interact directly with the WAVE complex. Doctoral thesis, UCL (University College London).

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Abstract

Ena/VASP proteins have emerged as key regulators of the actin cytoskeleton during cell migration. They are conserved from flies to mammals, where they consist of three family members: Mena, VASP and Evl. All three proteins localise to sites of cell adhesion and the leading edge of migrating cells, where they play an important role in regulating actin polymerization. Ena/VASP proteins consist of three domains, EVH1 and EVH2 domains, which are separated by a proline rich region. The EVH1 domain mediates the intra-cellular targeting of Ena/VASP proteins by interacting with FPPPP motifs found in proteins such as Zyxin and lamellipodin. The demonstration that Tes, which lacks an FPPPP motif binds to the EVH1 domain of Mena but not VASP and Evl via its LIM3 domain, indicates that EVH1 domains can also bind non-FPPPP containing proteins. My PhD project focused on using biochemical approaches to identify additional non-classical binding partners of the EVH1 domains of Ena/VASP proteins and elucidating their roles during cell migration. I have found that the WAVE complex, which activates Arp2/3 complex-dependent actin nucleation, binds directly to the EVH1 domain of Ena/VASP proteins and that this interaction was mediated by Abi. I identified the EVH1 binding site in both human and Drosophila Abi. By expressing Abi mutants deficient in EVH1 binding I was able to demonstrate that Ena/VASP proteins stabilize the WAVE complex the tip of lamellipodia in both Rat-2 cells as well as Drosophila S2 and S2R+ cells. Moreover, collaborative studies showed VASP could activate the WAVE complex in vitro and enhance the effect of Rac on activating the WAVE complex. My work has shown that Ena/VASP proteins are directly coupled to the WAVE complex, suggesting that they may regulate actin dynamics at the plasma membrane in a more coordinated fashion than previously thought.

Type:Thesis (Doctoral)
Title:Ena/VASP proteins interact directly with the WAVE complex
Language:English
UCL classification:UCL > School of Life and Medical Sciences > Faculty of Life Sciences

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