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.
Highlights
The centromere is a structural domain of mitotic and meiotic chromosomes essential for their correct segregation at cell division
We used a labelling with synaptonemal complex protein 3 (SYCP3), a structural protein component of lateral element of the synaptonemal complex (LE) of the synaptonemal complex, since it allowed us to discriminate among the different prophase I stages
Since we have previously described the presence of SYCP3 at the inner domain of metaphase I centromeres [28], we performed a double immunolabelling of Mitotic Centromere-Associated Kinesin (MCAK) and SYCP3 to test if these proteins colocalised
Summary
The centromere is a structural domain of mitotic and meiotic chromosomes essential for their correct segregation at cell division This domain is composed of the kinetochore and the subjacent chromatin. Besides INCENP, the others components of the chromosomal passenger proteins complex: Aurora-B, survivin, and recently Borealin/Dasra and Aurora-C, are localised at the inner domain [7,8]. This complex has been implied in several cell division processes such as chromatin modification, spindle assembly, the completion of cytokinesis and the correction of kinetochore attachment errors [8]. In HeLa cells the inhibition of Aurora-B by hesperadin caused an elevated frequency of chromosomes showing an abnormal syntelic orientation [10]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
