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

Abstract

Regulated RhoA localization at the cleavage site is mediated by the Sticky/Citron kinase and ensures RhoA’s proper activation and appropriate contractile ring dynamics during cytokinesis.

Tissue-specific control of midbody microtubule stability by Citron kinase through modulation of TUBB3 phosphorylation

“…Previous results indicated that the primary function of CIT-K, conserved from insects to mammals, is to promote the stability and the maturation of midbody before abscission. 15,[23][24][25] To assess whether this function may involve the stabilization of midbody microtubules, we measured the ratio of acetylated versus tyrosinated α-tubulin at the midbody of control cells and of cells lacking CIT-K. 28 Indeed, dynamic microtubules contain a relatively high amount of α-tubulin tyrosinated at its carboxyterminus, whereas stable microtubules show a high content of α-tubulin acetylated at the K40 residue. 29 We studied two cellular models characterized by different sensitivity to CIT-K loss and by different physiological relevance: cultures of proliferating neocortical neuronal progenitors obtained from control or from Cit-K knockout mice at embryonic day (E)12.5 and HeLa cells depleted of CIT-K by RNAi.…”

“…In addition to the previous studies implicating CIT-K in actindependent midbody stabilization, 23,25,53 these results add strong support the notion that CIT-K plays a crucial role in the crosstalk between actin and microtubules responsible for the maturation of midbody that precedes abscission. [23][24][25]54 The activity of CIT-K on microtubule stability is most likely independent from the reported interaction between CIT-K and KIF14. Indeed, although KIF14 may be functionally implicated in crosslinking midbody microtubules via its interaction with PRC1, 25 it does not seem to affect their stability (Figures 2a and b).…”

“…Indeed, CIT-K can stimulate actin polymerization 14,23 and has been shown to regulate abscission by stabilizing at the midbody the active form of RhoA and the actin-binding protein Anillin. 23,24 However, recent results have indicated that CIT-K is also capable of binding microtubules and of promoting midbody maturation by affecting the localization of the kinesins MKLP1 and KIF14 and of the microtubule-bundling protein PRC1. 25 These results raised the possibility that the function of CIT-K may also be related to microtubule organization and that context-dependent differences in microtubule stability may condition the requirement for CIT-K during cytokinesis.…”

Cytokinesis in Animal Cells

“…Two contractile ring proteins play this role: anillin and citron kinase (CIT-K). Both proteins associate with actin and myosin and interact directly with RhoA, although they do not seem to behave as canonical RhoA effectors (Madaule et al 1995;Piekny and Glotzer 2008;D'Avino 2009;Bassi et al 2011). In particular, CIT-K is required for proper RhoA localization, indicating that it behaves more like a RhoA regulator (Bassi et al 2011;Gai et al 2011).…”

Cytokinesis microtubule organisers at a glance

“…In addition, a carbohydrate-binding protein Nessun Dorma (NESD) binds centralspindlin and plays a role in late cytokinesis (Montembault et al, 2010). Another midzone factor, citron kinase, which regulates late cytokinesis events through Rho (Bassi et al, 2011;Gai et al, 2011), depends on KIF14 for its midzone localisation (Gruneberg et al, 2006).…”