Cdk1 Negatively Regulates Midzone Localization of the Mitotic Kinesin Mklp2 and the Chromosomal Passenger Complex

Abstract

The survival of eukaryotes depends on the accurate coordination of mitosis with cytokinesis. Key for the coordination of both processes is the chromosomal passenger complex (CPC) comprising Aurora-B, INCENP, survivin, and borealin. The translocation of the CPC from centromeres to the spindle midzone, a structure composed of antiparallel microtubules, at anaphase onset is critical for the completion of cytokinesis. In mammalian cells, the mitotic kinesin Mklp2 is essential for recruitment of the CPC to the spindle midzone. However, the mechanism regulating the binding of Mklp2 to microtubules has remained unknown. Here, we demonstrate that Mklp2 and the CPC mutually depend on each other for midzone localization; i.e., Mklp2 is mislocalized in INCENP-RNAi cells and vice versa. Remarkably, INCENP is required for localization of Mklp2 to the ends of stable microtubules in cells with low Cdk1 activity. In vitro assays revealed that the association between the CPC and Mklp2 is negatively regulated by Cdk1. Collectively, our data suggest that anaphase onset triggers the association between the CPC and Mklp2 and that this association targets the CPC-Mklp2 complex to the ends of stable microtubules in the spindle midzone.

Spindle Assembly and Chromosome Segregation Requires Central Spindle Proteins inDrosophilaOocytes

“…We suggest that this interaction occurs because the epitope tag fused to the N terminus of the Incenp allele causes the dominant phenotype, and there is a direct physical interaction between Subito and the N terminus of INCENP, as recently described for MKLP2 (Kitagawa et al 2014). That we observed consistent genetic interactions between Incenp and Cyclin B and some of its regulators, which are also known to regulate Subito/Mklp2 localization (Hummer and Mayer 2009;Kitagawa et al 2014), is consistent with a specific direct interaction between Subito and Incenp. A surprisingly strong interaction was also observed between Incenp and ncd mutants, suggesting that the NCD motor has an important role in central spindle assembly.…”

A haploid genetic screen identifies the G1/S regulatory machinery as a determinant of Wee1 inhibitor sensitivity

“…Nevertheless, Tyr-15 phosphorylation on Cdk1 was observed early after mitotic exit, indicative of Wee1 reactivation during mitotic exit (39), although this was only described to form a back-up mechanism during mitotic exit (40). Because Cdk1 phosphorylates (and thereby inhibits) multiple cytokinesis components including Separase, MKlp2, and Ect2, it is very likely that sustained Cdk1 activity may underlie the defective cytokinesis that was observed after Wee1 inhibition (41)(42)(43) (Fig. 4).…”

Cytokinesis and cancer

“…CDK1 phosphorylation of INCENP and Aurora B prevents the transfer of CPC in the central spindle, thus resulting in cytokinesis defects [17]. Apart from the proteins described above, which are the components of the central machinery of the spindle, there are many other proteins that concentrate on the central spindle during anaphase and telophase, including NuSAP, Orbit and ASP.…”

“…Microtubule-associated proteins PRC1 [13,14] Centralspindlin complex CYK-4 [2,15] MKLP1 [2,15] Chromosome passenger complex INCENP [16,17] Survinin [16,17] Borealin [16,17] Aurora B [16,17] ESRCTs and associated proteins CEP55 [30][31][32] TSG101 [31,32] ALIX [31,32] CHMP1B [33] Spastin [33] CHMP4B [31,32,34] FYVE-CENT [34] TTC19 [34] Kinesins KIF4A [14] MKLP2 [17] MPP1 [22] KIF14 [23] KIF13A [34] Additional proteins NuSAP [18] Orbit [19] ASP [20] TBCD [21] ECT2 [24] FIP3 [25] PLK1 [26,27] Septins [28] Anillin [29] during anaphase and cytokinesis and is important for the last step of abscission. CEP55 binds directly MKLP1 and is controlled by centralspindlin, since knockdown of centralspindlin abolishes CEP55 from the midbody [30].…”