Mechanism of N-Wasp Activation by Cdc42 and Phosphatidylinositol 4,5-Bisphosphate

By R. Rohatgi, H. H. Ho, Marc Kirschner. Journal of Cell Biology, 2000

662 citations recorded by the source corpus.

Neuronal Wiskott-Aldrich Syndrome protein (N-WASP) transmits signals from Cdc42 to the nucleation of actin filaments by Arp2/3 complex. Although full-length N-WASP is a weak activator of Arp2/3 complex, its activity can be enhanced by upstream regulators such as Cdc42 and PI(4,5)P2. We dissected this activation reaction and found that the previously described physical interaction between the NH2-terminal domain and the COOH-terminal effector domain of N-WASP is a regulatory interaction because it can inhibit the actin nucleation activity of the effector domain by occluding the Arp2/3 binding site. This interaction between the NH2- and COOH termini must be intramolecular because in solution N-WASP is a monomer. Phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) influences the activity of N-WASP through a conserved basic sequence element located near the Cdc42 binding site rather than through the WASp homology domain 1. Like Cdc42, PI(4,5)P2 reduces the affinity between the NH2- and COOH termini of the molecule. The use of a mutant N-WASP molecule lacking this basic stretch allowed us to delineate a signaling pathway in Xenopus extracts leading from PI(4,5)P2 to actin nucleation through Cdc42, N-WASP, and Arp2/3 complex. In this pathway, PI(4,5)P2 serves two functions: first, as an activator of N-WASP; and second, as an indirect activator of Cdc42.

Subfields: Cardiology and Cardiovascular Medicine, Cell Biology, Immunology and Allergy

View Paper: https://www.semanticscholar.org/paper/10afcf6f04489b812b5ef446b05417b36a7e6572

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Citations in the corpus

Mechanism of regulation of WAVE1-induced actin nucleation by Rac1 and Nck (2002, background): “Phosphatidylinositol(4,5)bisphosphate (PIP 2 ) can further activate N-WASP in cooperation with NCK or Cdc42 by binding to a basic region of N-WAS”
Cell migration: Rho GTPases lead the way. (2004, background): “Cdc42 activates WASp and N-WASp directly, although the lipid PI(4,5)P2 is an essential cofactor (Rohatgi et al., 1999, 2000).”
GPI-anchored proteins are delivered to recycling endosomes via a distinct cdc42-regulated, clathrin-independent pinocytic pathway. (2002, background): “At Arp2/3 complex, by directly binding to N-WASP and uncoupling the inhibitory activity of its N-terminal do-these times, markers of the clathrin-dependent pathway are present at close to steady-state levels in sorting main (Rohatgi et al., 2000).”
The role of the Rho GTPases in neuronal development. (2005, background): “This induces a conformational change that releases the WASP VCA domain from auto-inhibition, allowing it to activate the Arp2/3 complex to nucleate the formation of new actin filaments in vitro (Machesky et al. 1999; Rohatgi et al. 1999, 2000; Kim et al. 2000).”
The WASP–WAVE protein network: connecting the membrane to the cytoskeleton (2007, background): “Phosphoinositides interact with the basic region in WASP and N-WAS”
Regulation of actin assembly associated with protrusion and adhesion in cell migration. (2008, background): “Cdc42 and PIP2 disrupt the intramolecular interaction to unmask the VCA domain (100, 168, 183).”
Phosphoinositides: tiny lipids with giant impact on cell regulation. (2013, background): “It can dissociate the capping protein gelsolin from the ( ) end of actin (720, 721), it can increase actin nucleation by the Arp2/3 complex via binding to the N-WASP protein (1048, 1287), and it can inhibit the actin-severing activities of cofilin and the actin depolimerizing factor ADF (1162, 1772,”
Mechanism of filopodia initiation by reorganization of a dendritic network (2003, background): “One of its downstream effectors, N-WASP, is an ubiquitous activator of the Arp2/3 complex (Rohatgi et al., 1999, 2000), which significantly facilitates Cdc42induced filopodial formation (Miki et al., 1998), suggesting that the Arp2/3 complex may be involved in filopodial protrusion.”