SCAR knockouts in Dictyostelium: WASP assumes SCAR’s position and upstream regulators in pseudopods

Veltman, D. M., King, J. S., Machesky, L. M. and Insall, R. H. (2012) SCAR knockouts in Dictyostelium: WASP assumes SCAR’s position and upstream regulators in pseudopods. Journal of Cell Biology, 198(4), pp. 501-508. (doi: 10.1083/jcb.201205058) (PMID:22891261) (PMCID:PMC3514037)

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Under normal conditions, the Arp2/3 complex activator SCAR/WAVE controls actin polymerization in pseudopods, whereas Wiskott–Aldrich syndrome protein (WASP) assembles actin at clathrin-coated pits. We show that, unexpectedly, Dictyostelium discoideum SCAR knockouts could still spread, migrate, and chemotax using pseudopods driven by the Arp2/3 complex. In the absence of SCAR, some WASP relocated from the coated pits to the leading edge, where it behaved with similar dynamics to normal SCAR, forming split pseudopods and traveling waves. Pseudopods colocalized with active Rac, whether driven by WASP or SCAR, though Rac was activated to a higher level in SCAR mutants. Members of the SCAR regulatory complex, in particular PIR121, were not required for WASP regulation. We thus show that WASP is able to respond to all core upstream signals and that regulators coupled through the other members of SCAR’s regulatory complex are not essential for pseudopod formation. We conclude that WASP and SCAR can regulate pseudopod actin using similar mechanisms.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Machesky, Professor Laura and Insall, Professor Robert and King, Dr Jason
Authors: Veltman, D. M., King, J. S., Machesky, L. M., and Insall, R. H.
College/School:College of Medical Veterinary and Life Sciences > Institute of Cancer Sciences
Journal Name:Journal of Cell Biology
Publisher:Rockefeller University Press
ISSN (Online):1540-8140
Published Online:13 August 2012
Copyright Holders:Copyright © 2012 Veltman et al.
First Published:First published in Journal of Cell Biology 198(4):501-508
Publisher Policy:Reproduced under a Creative Commons License

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