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Cell Rep. 2015 Oct 20;13(3):460-468. doi: 10.1016/j.celrep.2015.08.008. Epub 2015 Oct 8.

Polar Ejection Forces Promote the Conversion from Lateral to End-on Kinetochore-Microtubule Attachments on Mono-oriented Chromosomes.

Author information

1
Chromosome Instability & Dynamics Laboratory, Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua do Campo Alegre 823, 4150-180 Porto, Portugal; Instituto de Investigação e Inovação em Saúde - i3S, Universidade do Porto, 4099-002 Porto, Portugal; Graduate Program in Areas of Basic and Applied Biology (GABBA), Instituto de Ciencias Biomedicas Abel Salazar da Universidade do Porto, Rua de Jorge Viterbo Ferreira no. 228, 4050-313 Porto, Portugal.
2
Chromosome Instability & Dynamics Laboratory, Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua do Campo Alegre 823, 4150-180 Porto, Portugal; Instituto de Investigação e Inovação em Saúde - i3S, Universidade do Porto, 4099-002 Porto, Portugal.
3
Biology Department, University of Massachusetts, Amherst, Amherst, MA 01003, USA.
4
Chromosome Instability & Dynamics Laboratory, Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua do Campo Alegre 823, 4150-180 Porto, Portugal; Instituto de Investigação e Inovação em Saúde - i3S, Universidade do Porto, 4099-002 Porto, Portugal; Cell Division Unit, Department of Experimental Biology, Faculty of Medicine, University of Porto, Alameda Prof. Hernâni Monteiro, 4200-319 Porto, Portugal. Electronic address: maiato@ibmc.up.pt.

Abstract

Chromosome bi-orientation occurs after conversion of initial lateral attachments between kinetochores and spindle microtubules into stable end-on attachments near the cell equator. After bi-orientation, chromosomes experience tension from spindle forces, which plays a key role in the stabilization of correct kinetochore-microtubule attachments. However, how end-on kinetochore-microtubule attachments are first stabilized in the absence of tension remains a key unanswered question. To address this, we generated Drosophila S2 cells undergoing mitosis with unreplicated genomes (SMUGs). SMUGs retained single condensed chromatids that attached laterally to spindle microtubules. Over time, laterally attached kinetochores converted into end-on attachments and experienced intra-kinetochore stretch/structural deformation, and SMUGs eventually exited a delayed mitosis with mono-oriented chromosomes after satisfying the spindle-assembly checkpoint (SAC). Polar ejection forces (PEFs) generated by Chromokinesins promoted the conversion from lateral to end-on kinetochore-microtubule attachments that satisfied the SAC in SMUGs. Thus, PEFs convert lateral to stable end-on kinetochore-microtubule attachments, independently of chromosome bi-orientation.

KEYWORDS:

chromokinesins; kinetochore; mitosis; mitosis with unreplicated genomes; spindle assembly checkpoint

PMID:
26456825
PMCID:
PMC4623360
DOI:
10.1016/j.celrep.2015.08.008
[Indexed for MEDLINE]
Free PMC Article

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