title: Citron kinase mediates transition from constriction to abscission through its coiled-coil domain.
abstract: Cytokinesis is initiated by constriction of the cleavage furrow, and completed with separation of the two daughter cells by abscission. Control of transition from constriction to abscission is therefore crucial for cytokinesis. However, the underlying mechanism is largely unknown. Here, we analyze the role of Citron kinase (Citron-K) that localizes at the cleavage furrow and the midbody, and dissect its action mechanisms during this transition. Citron-K forms a stable ring-like structure at the midbody and its depletion affects the maintenance of the intercellular bridge, resulting in fusion of two daughter cells after the cleavage furrow ingression. RNA interference (RNAi) targeting Citron-K reduced accumulation of RhoA, Anillin, and septins at the intercellular bridge in mid telophase, and impaired concentration and maintenance of KIF14 and PRC1 at the midbody in late telophase. RNAi rescue experiments revealed that these functions of Citron-K are mediated by its coiled-coil (CC) domain, and not by its kinase domain. The C-terminal part of CC contains a Rho-binding domain and a cluster-forming region and is important for concentrating Citron-K from the cleavage furrow to the midbody. The N-terminal part of CC directly binds to KIF14, and this interaction is required for timely transfer of Citron-K to the midbody after furrow ingression. We propose that the CC-domain-mediated translocation and actions of Citron-K ensure proper stabilization of the midbody structure during the transition from constriction to abscission.
authors: Department of Pharmacology, Kyoto University Faculty of Medicine, Kyoto 606-8501, Japan. sadanori.watanabe@bio.nagoya-u.ac.jp
authors: Sadanori
authors: S
authors: Watanabe
authors: Tihana
authors: T
authors: De Zan
authors: Toshimasa
authors: T
authors: Ishizaki
authors: Shuh
authors: S
authors: Narumiya
mesh_terms: D000818:Animals; D002460:Cell Line; D003285:Contractile Proteins / Q000378:metabolism; D048749:Cytokinesis / Q000235:genetics / Q000502:physiology; D006367:HeLa Cells; D006801:Humans; D047468:Immunoprecipitation; D047908:Intracellular Signaling Peptides and Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008856:Microscopy, Fluorescence; D041681:NIH 3T3 Cells; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D034622:RNA Interference; D058112:Septins / Q000378:metabolism; D020742:rhoA GTP-Binding Protein / Q000378:metabolism
chemical_list: D003285:Contractile Proteins; D047908:Intracellular Signaling Peptides and Proteins; C095886:anillin; C115635:citron-kinase; D017346:Protein Serine-Threonine Kinases; D058112:Septins; D020742:rhoA GTP-Binding Protein
keywords: Abscission; Cytokinesis; Midbody