Dissecting the role of Rho-mediated signaling in contractile ring formation

In anaphase, microtubules provide a specification signal for positioning of the contractile ring. However, the nature of the signal remains unknown. The small GTPase Rho is a potent regulator of cytokinesis, but the involvement of Rho in contractile ring formation is disputed. Here, we show that Rho...

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Bibliographic Details
Published in:Molecular biology of the cell 2006-01, Vol.17 (1), p.43-55
Main Authors: Kamijo, Keiju, Ohara, Naoya, Abe, Mitsuhiro, Uchimura, Takashi, Hosoya, Hiroshi, Lee, Jae-Seon, Miki, Toru
Format: Article
Language:English
Subjects:
Actins - metabolism
Cytokinesis
Gene Expression Regulation - genetics
HeLa Cells
Humans
Microtubule-Associated Proteins - metabolism
Microtubules - metabolism
Myosins - metabolism
Protein Binding
Protein Transport
rac GTP-Binding Proteins - metabolism
rho GTP-Binding Proteins - classification
rho GTP-Binding Proteins - genetics
rho GTP-Binding Proteins - metabolism
RNA Interference
Signal Transduction
Spindle Apparatus - metabolism
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Summary:In anaphase, microtubules provide a specification signal for positioning of the contractile ring. However, the nature of the signal remains unknown. The small GTPase Rho is a potent regulator of cytokinesis, but the involvement of Rho in contractile ring formation is disputed. Here, we show that Rho serves as a microtubule-dependent signal that specifies the position of the contractile ring. We found that Rho translocates to the equatorial region before furrow ingression. The Rho-specific inhibitor C3 exoenzyme and small interfering RNA to the Rho GDP/GTP exchange factor ECT2 prevent this translocation and disrupt contractile ring formation, indicating that active Rho is required for contractile ring formation. ECT2 forms a complex with the GTPase-activating protein MgcRacGAP and the kinesinlike protein MKLP1 at the central spindle, and the localization of ECT2 at the central spindle depends on MgcRacGAP and MKLP1. In addition, we show that the bundled microtubules direct Rho-mediated signaling molecules to the furrowing site and regulate furrow formation. Our study provides strong evidence for the requirement of Rho-mediated signaling in contractile ring formation.
ISSN:1059-1524
1939-4586
DOI:10.1091/mbc.E05-06-0569