Abstract
Cdc42 is a small GTPase of the Rho family which regulates the formation of actin filaments to generate filopodia1,2. Although there are several proteins such as PAK3, ACK4 and WASP (WiskottโAldrich syndrome protein)5 that bind Cdc42 directly, none of these can account for the filopodium formation induced by Cdc42. Here we demonstrate that before it can induce filopodium formation, Cdc42 must bind a WASP-related protein, N-WASP, that is richest in neural tissues6 but is expressed ubiquitously. N-WASP induces extremely long actin microspikes only when co-expressed with active Cdc42, whereas WASP, which is expressed in haematopoietic cells, does not, despite the structural similarities between WASP and N-WASP. In a cell-free system, addition of active Cdc42 significantly stimulates the actin-depolymerizing activity of N-WASP, creating free barbed ends from which actin polymerization can then take place. This activation seems to be caused by exposure of N-WASP's actin-depolymerizing region induced by Cdc42 binding.
This is a preview of subscription content, access via your institution
Access options
Subscribe to this journal
Receive 52 print issues and online access
$199.00 per year
only $3.83 per issue
Buy this article
- Purchase on SpringerLink
- Instant access to the full article PDF.
USD 39.95
Prices may be subject to local taxes which are calculated during checkout
Similar content being viewed by others
References
Nobes, C. D. & Hall, A. Rho, rac, and cdc GTPases regulate the assembly of multimolecular focal complexes associated with actin stress fibers, lamellipodia, and filopodia. Cell 81, 53โ62 (1995).
Kozma, R., Ahmed, S., Best, A. & Lim, L. The GTPase-activating protein n-chimaerin cooperates with Rac1 and Cdc42Hs to induce the formation of lamellipodia and filopodia. Mol. Cell. Biol. 15, 1942โ1952 (1995).
Manser, E., Leung, T., Salihuddin, H., Zhao, Z. S. & Lim, L. Abrain serine/threonine protein kinase activated by Cdc42 and Rac1. Nature 367, 40โ46 (1994).
Manser, E., Leung, T., Salihuddin, H., Zhao, Z. S. & Lim, L. Anon-receptor tyrosine kinase that inhibits the GTPase activity of p21cdc42. Nature 363, 364โ367 (1993).
Symons, M. et al. WiskottโAldrich syndrome protein, a novel effector for the GTPase CDC42Hs, is implicated in actin polymerization. Cell 84, 723โ734 (1996).
Miki, H., Miura, K. & Takenawa, T. N-WASP, a novel actin-depolymerizing protein, regulates the cortical cytoskeletal rearrangement in a PIP2-dependent manner downstream of tyrosine kinases. EMBO J. 15, 5326โ5335 (1996).
Burbelo, P. D., Drechsel, D. & Hall, A. Aconserved binding motif defines numerous candidate target proteins for both Cdc42 and Rac GTPases. J. Biol. Chem. 270, 29071โ29074 (1995).
Aspenstrom, P., Lindberg, U. & Hall, A. Two GTPases, Cdc42 and Rac, bind directly to a protein implicated in the immunodeficiency disorder WiskottโAldrich syndrome. Curr. Biol. 15, 5725โ5731 (1996).
Lamarche, N. et al. Rac and Cdc42 induce actin polymerization and G1 cell cycle progression independently of p65PAK and the JNK/SAPK MAP kinase cascade. Cell 87, 519โ529 (1996).
Nishida, E., Maekawa, S. & Sakai, H. Cofilin, a protein in porcine brain that binds to actin filaments and inhibits their interactions with myosin and tropomyosin. Biochemistry 23, 5307โ5317 (1984).
Aizawa, H. et al. Identification, characterization, and intracellular distribution of cofilin in Dictyostelium discoideum. J. Biol. Chem. 270, 10923โ10932 (1995).
Pantaloni, D. & Carlier, M.-F. How profilin promotes actin filament assembly in the presence of thymosin ฮฒ4. Cell 75, 1007โ1014 (1993).
Fukuoka, M., Miki, H. & Takenawa, T. Identification of N-WASP homologs in human and rat brain. Gene 196, 43โ48 (1997).
Komuro, R., Sasaki, T., Takaishi, K., Orita, S. & Takai, Y. Involvement of Rho and Rac small G proteins and Rho GDI in Ca2+-dependent exocytosis from PC12 cells. Genes to Cells 1, 943โ951 (1996).
Self, A. J. & Hall, A. Purification of recombinant Rho/Rac/G25K from Escherichia coli. Meth. Enzymol. 256, 3โ10 (1995).
Acknowledgements
We thank S. Suetsugu and Y. Banzai for their skilful technical assistance. This work was supported in part by a Grant-in-Aid for Cancer Research from the Ministry of Education, Science, and Culture of Japan and a Grant-in-Aid for Research for the Future Program from the Japan Society for the Promotion of Science.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Miki, H., Sasaki, T., Takai, Y. et al. Induction of filopodium formation by a WASP-related actin-depolymerizing protein N-WASP. Nature 391, 93โ96 (1998). https://doi.org/10.1038/34208
Received:
Accepted:
Published:
Issue date:
DOI: https://doi.org/10.1038/34208
