Aurora B Regulates MCAK at the Mitotic Centromere

Abstract

Chromosome orientation and alignment within the mitotic spindle requires the Aurora B protein kinase and the mitotic centromere-associated kinesin (MCAK). Here, we report the regulation of MCAK by Aurora B. Aurora B inhibited MCAK's microtubule depolymerizing activity in vitro, and phospho-mimic (S/E) mutants of MCAK inhibited depolymerization in vivo. Expression of either MCAK (S/E) or MCAK (S/A) mutants increased the frequency of syntelic microtubule-kinetochore attachments and mono-oriented chromosomes. MCAK phosphorylation also regulates MCAK localization: the MCAK (S/E) mutant frequently localized to the inner centromere while the (S/A) mutant concentrated at kinetochores. We also detected two different binding sites for MCAK using FRAP analysis of the different MCAK mutants. Moreover, disruption of Aurora B function by expression of a kinase-dead mutant or RNAi prevented centromeric targeting of MCAK. These results link Aurora B activity to MCAK function, with Aurora B regulating MCAK's activity and its localization at the centromere and kinetochore.

MCAK and Paclitaxel Have Differential Effects on Spindle Microtubule Organization and Dynamics

“…This is consistent with the complex localization of MCAK in the spindle and the highly complicated phosphorregulatory schemes that regulate its localization and activity at centromeres and at spindle poles (Andrews et al, 2004;Gorbsky, 2004;Lan et al, 2004;Ohi et al, 2004;Knowlton et al, 2006;Zhang et al, 2007Zhang et al, , 2008. This suggests that MCAK is responsible for preferentially altering the dynamics individual MT subclasses and raises the important question of how other MT dynamics effectors contribute to the control of spindle MT subclasses.…”

“…Our data are consistent with the recent findings of Wordeman et al (2007), who propose an attractive idea that the role of MCAK is to loosen up MT ends to facilitate directional coordination of chromosome motility and MT release. Another interesting observation is that although it has been clearly established that MCAK is a substrate of Aurora B kinase (Andrews et al, 2004;Lan et al, 2004;Sampath et al, 2004;Zhang et al, 2007), the magnitude of the effects of MCAK inhibition versus Aurora B inhibition on the t 1/2 value of the K-fiber strongly supports the idea that Aurora B causes release of aberrant MT attachments primarily through a mechanism that does not rely solely on MCAK DeLuca et al, 2006;Wordeman et al, 2007).…”

“…Our data are consistent with the recent findings of Wordeman et al (2007), who propose an attractive idea that the role of MCAK is to loosen up MT ends to facilitate directional coordination of chromosome motility and MT release. Another interesting observation is that although it has been clearly established that MCAK is a substrate of Aurora B kinase (Andrews et al, 2004;Lan et al, 2004;Sampath et al, 2004;Zhang et al, 2007), the magnitude of the effects of MCAK inhibition versus Aurora B inhibition on the t 1/2 value of the K-fiber strongly supports the idea that Aurora B causes release of aberrant MT attachments primarily through a mechanism that does not rely solely on MCAK DeLuca et al, 2006;Wordeman et al, 2007).Overall our work supports a model where MCAK differentially affects the MT subclasses which coexist during mitosis, with specific effects on K-fibers and astral MTs. This is consistent with the complex localization of MCAK in the spindle and the highly complicated phosphorregulatory schemes that regulate its localization and activity at centromeres and at spindle poles (Andrews et al, 2004;Gorbsky, 2004;Lan et al, 2004;Ohi et al, 2004;Knowlton et al, 2006;Zhang et al, 2007Zhang et al, , 2008.…”

Centromere Targeting of the Chromosomal Passenger Complex Requires a Ternary Subcomplex of Borealin, Survivin, and the N-Terminal Domain of INCENP

“…Consequently, knockdown or inhibition of Aurora B or any of the other subunits of the CPC results in chromosome congression defects, kinetochore-microtubule attachment errors, lagging chromosomes in anaphase, and failure of cytokinesis (Vagnarelli and Earnshaw, 2004;Tanaka, 2005). Consistent with the idea that the localization of the CPC is important for target recognition by its kinase subunit, Aurora B has been demonstrated to phosphorylate proteins at the centromere, such as CENP-A and mitotic centromere-associated kinesin (MCAK) (Zeitlin et al, 2001;Andrews et al, 2004;Lan et al, 2004;Ohi et al, 2004), and at the central spindle and midbody, e.g., Mklp1, MgcRacGap, and vimentin (Goto et al, 2003;Minoshima et al, 2003;Guse et al, 2005). Yet, the molecular details of how phosphorylation by Aurora B influences its different substrates and thus regulates the different stages of the cell cycle are still not clear.…”

Contractile Ring-independent Localization of DdINCENP, a Protein Important for Spindle Stability and Cytokinesis

“…For example, the localization of metazoan MKLP1, a kinesin essential for central spindle formation, is dependent on IN-CENP function (Zhu et al, 2005). Similarly, the activity of vertebrate MCAK, a microtubule-depolymerizing protein, is regulated through its phosphorylation by Aurora B kinase (Andrews et al, 2004;Lan et al, 2004). Although a Dictyostelium homolog of MCAK has yet to be identified, the homolog of MCAK's antagonist, XMAP215/TOGp, has been characterized as the Dictyostelium DdCP224 protein.…”