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Dictyostelium Dock180-related RacGEFs regulate the actin cytoskeleton during cell motility

Alessia Para1, Miriam Krischke, Sylvain Merlot

  • 1Section of Cell and Developmental Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093-0380, USA.

Molecular Biology of the Cell
|November 28, 2008
PubMed

Insights

Dictyostelium amoeboid cell motility relies on F-actin polymerization. DockA and DockD proteins regulate cell speed, with DockD enhancing movement by promoting F-actin polymerization and pseudopod extension.

Area of Science:

  • Cell biology
  • Biochemistry

Background:

  • Cell motility is crucial for amoeboid cells, involving F-actin polymerization and membrane protrusion.
  • The Dictyostelium Dock180 family of RacGEFs, including DockA and DockD, are implicated in regulating cell movement.

Purpose of the Study:

  • To investigate the roles of DockA and DockD in Dictyostelium cell motility.
  • To elucidate the molecular mechanisms by which these proteins regulate F-actin polymerization and cell speed.

Main Methods:

  • Gene deletion and complementation experiments in Dictyostelium.
  • Analysis of cell speed and chemotaxis.
  • Proteomic analysis to identify interacting proteins and substrates.

Main Results:

  • Deletion of DockA or DockD reduced cell speed, with the double mutant showing an enhanced phenotype, indicating functional redundancy.
  • Overexpression of DockD increased cell speed by enhancing F-actin polymerization at pseudopod extension sites.
  • DockD localization to the cell cortex and leading edge is PI3K-dependent, suggesting a link to PtdIns(3,4,5)P(3) signaling.
  • DdELMO1 was found to associate with DockD, and Rac1A and RacC were identified as potential substrates.

Conclusions:

  • DockA and DockD play redundant roles in regulating Dictyostelium cell speed and motility.
  • DockD is a key regulator of F-actin polymerization and pseudopod extension, linking PI3K signaling to actin dynamics.
  • The findings highlight the conserved molecular mechanisms of Dock180-related protein function in cell motility.

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