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

Zuni I. Bassi, Koen J. Verbrugghe, Luisa Capalbo, Stephen Gregory, Emilie Montembault, David M. Glover, Pier Paolo D'Avino

Research output: Contribution to journalArticlepeer-review

50 Citations (Scopus)


In many organisms, the small guanosine triphospha-tase RhoA controls assembly and contraction of the actomyosin ring during cytokinesis by activating dif-ferent 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.

Original languageEnglish
Pages (from-to)595-603
Number of pages9
JournalJournal of Cell Biology
Issue number4
Publication statusPublished - 14 Nov 2011
Externally publishedYes


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