A Perikinetochoric Ring Defined by MCAK and Aurora-B as a Novel Centromere Domain

Abstract

Mitotic Centromere-Associated Kinesin (MCAK) is a member of the kinesin-13 subfamily of kinesin-related proteins. In mitosis, this microtubule-depolymerising kinesin seems to be implicated in chromosome segregation and in the correction of improper kinetochore-microtubule interactions, and its activity is regulated by the Aurora-B kinase. However, there are no published data on its behaviour and function during mammalian meiosis. We have analysed by immunofluorescence in squashed mouse spermatocytes, the distribution and possible function of MCAK, together with Aurora-B, during both meiotic divisions. Our results demonstrate that MCAK and Aurora-B colocalise at the inner domain of metaphase I centromeres. Thus, MCAK shows a “cone”-like three-dimensional distribution beneath and surrounding the closely associated sister kinetochores. During the second meiotic division, MCAK and Aurora-B also colocalise at the inner centromere domain as a band that joins sister kinetochores, but only during prometaphase II in unattached chromosomes. During chromosome congression to the metaphase II plate, MCAK relocalises and appears as a ring below each sister kinetochore. Aurora-B also relocalises to appear as a ring surrounding and beneath kinetochores but during late metaphase II. Our results demonstrate that the redistribution of MCAK at prometaphase II/metaphase II centromeres depends on tension across the centromere and/or on the interaction of microtubules with kinetochores. We propose that the perikinetochoric rings of MCAK and Aurora-B define a novel transient centromere domain at least in mouse chromosomes during meiosis. We discuss the possible functions of MCAK at the inner centromere domain and at the perikinetochoric ring during both meiotic divisions.

Dynamic localization of SMC5/6 complex proteins during mammalian meiosis and mitosis implies functions in distinct chromosome processes

“…Because SMC6 was unexpectedly detected at a strand that stretched between sister kinetochores during the metaphase II to anaphase II transition, we investigated the behavior of SMC6 relative to Aurora-B, a chromosomal passenger complex kinase that redistributes at the inner centromere domain during meiosis II (Parra et al, 2006). Our results showed that SMC6 and Aurora-B colocalized at the inner domain of 41.7% (15 out of 36) metaphase II centromeres ( Fig.…”

“…In this regard, the persistence of SMC6 at a strand joining sister kinetochores at metaphase II centromeres, after the redistribution of Aurora-B (Parra et al, 2006), and the 'stretching' of that strand, which still associates the kinetochores of segregating anaphase II chromatids, where Topo IIa is also present, suggests that the SMC5/6 complexes regulate sister-chromatid centromere cohesion. Notably, it has been recently reported that the SMC5/6 complexes might be involved in sister-chromatid cohesion and dissolution of aberrant DNA-mediated sister-chromatid linkages after DNA replication in budding and fission yeasts (Outwin et al, 2009;Bermúdez-López et al, 2010), chicken cells (Stephan et al, 2011) and HeLa cells (Behlke-Steinert et al, 2009).…”

Lucky 13 - microtubule depolymerisation by kinesin-13 motors

“…The kinetochore consists of distinct domainsthe centromeric, DNA-proximal region, the inner kinetochore and the outer kinetochore plate, where spindle MTs attach (reviewed in Maiato et al, 2004;Moore and Wordeman, 2004b;Chan et al, 2005;Parra et al, 2006). Kinesin-13 motors are believed to be active at all these sites.…”

“…Regulation of kinesin-13 motors (specifically MCAK) at the kinetochore by the aurora B kinase is also a focus of attention (Andrews et al, 2004;Lan et al, 2004;Ohi et al, 2004;Parra et al, 2006). Aurora B has a general role promoting chromatid biorientation and it phosphorylates MCAK on several serine/threonine residues, including within the neck, thereby inactivating it.…”

Functional and Spatial Regulation of Mitotic Centromere- Associated Kinesin by Cyclin-Dependent Kinase 1

“…Thus, the precise control of the localization and activity of MCAK is crucial for maintaining genetic integrity during mitosis. Regulation of MCAK on the centromeres/kinetochores by Aurora B kinase in mitosis has been intensively investigated (1,28,29,43). The data reveal that MCAK is phosphorylated on several serine/ threonine residues by Aurora B, which inhibits the microtubule-destabilizing activity of MCAK and regulates its localization on chromosome arms/centromeres/kinetochores during mitosis (1,18,28).…”