The RhoGAP activity of CYK-4/MgcRacGAP functions non-canonically by promoting RhoA activation during cytokinesis

  1. Donglei Zhang
  2. Michael Glotzer  Is a corresponding author
  1. University of Chicago, United States

Abstract

Cytokinesis requires activation of the GTPase RhoA. ECT-2, the exchange factor responsible for RhoA activation, is regulated to ensure spatiotemporal control of contractile ring assembly. Centralspindlin, composed of the Rho family GTPase-activating protein (RhoGAP) MgcRacGAP/CYK-4 and the kinesin MKLP1/ZEN-4, is known to activate ECT-2, but the underlying mechanism is not understood. We report that ECT-2-mediated RhoA activation depends on the ability of CYK-4 to localize to the plasma membrane, bind RhoA, and promote GTP hydrolysis by RhoA. Defects resulting from loss of CYK-4 RhoGAP activity can be rescued by activating mutations in ECT-2 or depletion of RGA-3/4, which functions as a conventional RhoGAP for RhoA. Consistent with CYK-4 RhoGAP activity contributing to GEF activation, the catalytic domains of CYK-4 and ECT-2 directly interact. Thus, counterintuitively, CYK-4 RhoGAP activity promotes RhoA activation. We propose that the most active form of the cytokinetic RhoGEF involves complex formation between ECT-2, centralspindlin and RhoA.

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Author details

  1. Donglei Zhang

    Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, United States
    Competing interests
    The authors declare that no competing interests exist.
  2. Michael Glotzer

    Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, United States
    For correspondence
    mglotzer@uchicago.edu
    Competing interests
    The authors declare that no competing interests exist.

Copyright

© 2015, Zhang & Glotzer

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.

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  1. Donglei Zhang
  2. Michael Glotzer
(2015)
The RhoGAP activity of CYK-4/MgcRacGAP functions non-canonically by promoting RhoA activation during cytokinesis
eLife 4:e08898.
https://doi.org/10.7554/eLife.08898

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https://doi.org/10.7554/eLife.08898