Sticky/Citron kinase maintains proper RhoA localization at the cleavage site during cytokinesis

In many organisms, the small guanosine triphosphatase RhoA controls assembly and contraction of the actomyosin ring during cytokinesis by activating different effectors. Although the role of some RhoA effectors like formins and Rho kinase is reasonably understood, the functions of another putative e...

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Bibliographic Details
Published in:The Journal of cell biology 2011-11, Vol.195 (4), p.595-603
Main Authors: Bassi, Zuni I, Verbrugghe, Koen J, Capalbo, Luisa, Gregory, Stephen, Montembault, Emilie, Glover, David M, D'Avino, Pier Paolo
Format: Article
Language:English
Subjects:
Animals
Cellular Biology
Cytokinesis
Cytoplasm
Drosophila - cytology
Drosophila - metabolism
Drosophila Proteins - metabolism
Insects
Intracellular Signaling Peptides and Proteins - metabolism
Kinases
Life Sciences
Phosphorylation
Protein Serine-Threonine Kinases - metabolism
rho GTP-Binding Proteins - metabolism
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Summary:In many organisms, the small guanosine triphosphatase RhoA controls assembly and contraction of the actomyosin ring during cytokinesis by activating different effectors. Although the role of some RhoA effectors like formins and Rho kinase is reasonably understood, the functions of another putative effector, Citron kinase (CIT-K), are still debated. In this paper, we show that, contrary to previous models, the Drosophila melanogaster CIT-K orthologue Sticky (Sti) does not require interaction with RhoA to localize to the cleavage site. Instead, RhoA fails to form a compact ring in late cytokinesis after Sti depletion, and this function requires Sti kinase activity. Moreover, we found that the Sti Citron-Nik1 homology domain interacts with RhoA regardless of its status, indicating that Sti is not a canonical RhoA effector. Finally, Sti depletion caused an increase of phosphorylated myosin regulatory light chain at the cleavage site in late cytokinesis. We propose that Sti/CIT-K maintains correct RhoA localization at the cleavage site, which is necessary for proper RhoA activity and contractile ring dynamics.
ISSN:0021-9525
1540-8140
DOI:10.1083/jcb.201105136