Polo-like kinase 1 directs assembly of the HsCyk-4 RhoGAP/Ect2 RhoGEF complex to initiate cleavage furrow formation

PLoS Biol. 2009 May 5;7(5):e1000110. doi: 10.1371/journal.pbio.1000110. Epub 2009 May 26.

Abstract

To complete cell division with high fidelity, cytokinesis must be coordinated with chromosome segregation. Mammalian Polo-like kinase 1, Plk1, may function as a critical link because it is required for chromosome segregation and establishment of the cleavage plane following anaphase onset. A central spindle-localized pool of the RhoGEF Ect2 promotes activation of the small GTPase RhoA, which drives contractile ring assembly at the equatorial cortex. Here, we have investigated how Plk1 promotes the central spindle recruitment of Ect2. Plk1 phosphorylates the noncatalytic N terminus of the RhoGAP HsCyk-4 at the central spindle, creating a phospho-epitope recognized by the BRCA1 C-terminal (BRCT) repeats of Ect2. Failure to phosphorylate HsCyk-4 blocks Ect2 recruitment to the central spindle and the subsequent induction of furrowing. Microtubules, as well as the microtubule-associated protein (MAP) Prc1, facilitate Plk1 phosphorylation of HsCyk-4. Characterization of a phosphomimetic version of HsCyk-4 indicates that Plk1 promotes Ect2 recruitment through multiple targets. Collectively, our data reveal that formation of the HsCyk-4-Ect2 complex is subject to multiple layers of regulation to ensure that RhoA activation occurs between the segregated sister chromatids during anaphase.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Biological Transport / drug effects
  • Cell Cycle Proteins / antagonists & inhibitors
  • Cell Cycle Proteins / metabolism*
  • Enzyme Inhibitors / pharmacology
  • Fluorescent Antibody Technique
  • GTPase-Activating Proteins / metabolism*
  • Guanine Nucleotide Exchange Factors / metabolism*
  • HeLa Cells
  • Humans
  • Immunoblotting
  • Phosphorylation / drug effects
  • Protein Binding / drug effects
  • Protein-Serine-Threonine Kinases / antagonists & inhibitors
  • Protein-Serine-Threonine Kinases / metabolism*
  • Proto-Oncogene Proteins / antagonists & inhibitors
  • Proto-Oncogene Proteins / metabolism*
  • Rho Guanine Nucleotide Exchange Factors
  • Serine / metabolism
  • Two-Hybrid System Techniques

Substances

  • Cell Cycle Proteins
  • ECT2 protein, human
  • Enzyme Inhibitors
  • GTPase-Activating Proteins
  • Guanine Nucleotide Exchange Factors
  • PRC1 protein, human
  • Proto-Oncogene Proteins
  • Rho Guanine Nucleotide Exchange Factors
  • mgcRacGAP
  • rho GTPase-activating protein
  • Serine
  • Protein-Serine-Threonine Kinases
  • polo-like kinase 1