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Mol Biol Cell. 2015 Apr 1;26(7):1225-37. doi: 10.1091/mbc.E14-09-1366. Epub 2015 Feb 5.

CENP-32 is required to maintain centrosomal dominance in bipolar spindle assembly.

Author information

1
Wellcome Trust Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3JR, United Kingdom Medical School, Kochi University, Kohasu, Oko-cho, Nankoku, Kochi 783-8505, Japan shinya.ohta@kochi-u.ac.jp bill.earnshaw@ed.ac.uk.
2
Wellcome Trust Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3JR, United Kingdom.
3
Medical School, Kochi University, Kohasu, Oko-cho, Nankoku, Kochi 783-8505, Japan.
4
Department of Molecular Genetics, National Institute of Genetics and the Graduate University for Advanced Studies, Mishima, Shizuoka 411-8540, Japan.
5
Wellcome Trust Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3JR, United Kingdom shinya.ohta@kochi-u.ac.jp bill.earnshaw@ed.ac.uk.

Abstract

Centrosomes nucleate spindle formation, direct spindle pole positioning, and are important for proper chromosome segregation during mitosis in most animal cells. We previously reported that centromere protein 32 (CENP-32) is required for centrosome association with spindle poles during metaphase. In this study, we show that CENP-32 depletion seems to release centrosomes from bipolar spindles whose assembly they had previously initiated. Remarkably, the resulting anastral spindles function normally, aligning the chromosomes to a metaphase plate and entering anaphase without detectable interference from the free centrosomes, which appear to behave as free asters in these cells. The free asters, which contain reduced but significant levels of CDK5RAP2, show weak interactions with spindle microtubules but do not seem to make productive attachments to kinetochores. Thus CENP-32 appears to be required for centrosomes to integrate into a fully functional spindle that not only nucleates astral microtubules, but also is able to nucleate and bind to kinetochore and central spindle microtubules. Additional data suggest that NuMA tethers microtubules at the anastral spindle poles and that augmin is required for centrosome detachment after CENP-32 depletion, possibly due to an imbalance of forces within the spindle.

PMID:
25657325
PMCID:
PMC4454171
DOI:
10.1091/mbc.E14-09-1366
[Indexed for MEDLINE]
Free PMC Article

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