WIP provides an essential link between Nck and N-WASP during Arp2/3-dependent actin polymerization.

Nck links phosphotyrosine-based signaling to Arp2/3-dependent actin polymerization during many different cellular processes as well as actin-based motility of enteropathogenic Escherichia coli (EPEC), vaccinia, and other vertebrate poxviruses by interacting with N-WASP/WASP. Nck also binds WASP-interacting protein (WIP), which inhibits the ability of N-WASP to activate the Arp2/3 complex until it receives an appropriate signaling input. Using mouse embryonic fibroblasts (MEFs) lacking Nck, WIP, or N-WASP, we have investigated whether an interaction of Nck with both WIP and N-WASP is required for their recruitment to vaccinia during Arp2/3-dependent actin assembly. We find that WIP or its homolog WIRE is required for N-WASP recruitment and actin-based motility of the virus. WIP contains two Nck-binding sites and is recruited to the virus, bound to N-WASP, by interacting with the second SH3 domain of Nck. N-WASP also contains two Nck-binding sites, but its recruitment is dependent on its interaction with WIP rather than Nck. The first and third SH3 domains of Nck are not required to recruit the WIP:N-WASP complex but are essential to stimulate actin assembly. We have established that WIP acts as an essential link between Nck and N-WASP. Our observations provide important insights into the hierarchy and connections in one of the major cellular signaling networks stimulating Arp2/3 complex-dependent actin polymerization.

Donnelly SK ，Weisswange I ，Zettl M ，Way M ... -  《-》

Enteropathogenic Escherichia coli and vaccinia virus do not require the family of WASP-interacting proteins for pathogen-induced actin assembly.

Garber JJ ，Takeshima F ，Antón IM ，Oyoshi MK ，Lyubimova A ，Kapoor A ，Shibata T ，Chen F ，Alt FW ，Geha RS ，Leong JM ，Snapper SB ... -  《-》

A complex of N-WASP and WIP integrates signalling cascades that lead to actin polymerization.

:Wiskott-Aldrich syndrome protein (WASP) and N-WASP have emerged as key proteins connecting signalling cascades to actin polymerization. Here we show that the amino-terminal WH1 domain, and not the polyproline-rich region, of N-WASP is responsible for its recruitment to sites of actin polymerization during Cdc42-independent, actin-based motility of vaccinia virus. Recruitment of N-WASP to vaccinia is mediated by WASP-interacting protein (WIP), whereas in Shigella WIP is recruited by N-WASP. Our observations show that vaccinia and Shigella activate the Arp2/3 complex to achieve actin-based motility, by mimicking either the SH2/SH3-containing adaptor or Cdc42 signalling pathways to recruit the N-WASP-WIP complex. We propose that the N-WASP-WIP complex has a pivotal function in integrating signalling cascades that lead to actin polymerization.

Moreau V ，Frischknecht F ，Reckmann I ，Vincentelli R ，Rabut G ，Stewart D ，Way M ... -  《NATURE CELL BIOLOGY》

The rate of N-WASP exchange limits the extent of ARP2/3-complex-dependent actin-based motility.

Weisswange I ，Newsome TP ，Schleich S ，Way M ... -  《-》

Cdc42 and the Rho GEF intersectin-1 collaborate with Nck to promote N-WASP-dependent actin polymerisation.

Humphries AC ，Donnelly SK ，Way M 《-》