Rad51-dependent aberrant chromosome structures at telomeres and ribosomal DNA activate the spindle assembly checkpoint.

The spindle assembly checkpoint (SAC) monitors defects in kinetochore-microtubule attachment or lack of tension at kinetochores and arrests cells at prometaphase. In fission yeast, the double mutant between pot1Δ and the helicase-dead point mutant of the RecQ helicase Rqh1 gene (rqh1-hd) accumulates Rad51-dependent recombination intermediates at telomeres and enters mitosis ...
with those intermediates. Here, we found that SAC-dependent prometaphase arrest occurred more frequently in pot1Δ rqh1-hd double mutants than in rqh1-hd single mutants. SAC-dependent prometaphase arrest also occurred more frequently in rqh1-hd single mutants after cells were released from DNA replication block compared to the rqh1-hd single mutant in the absence of exogenous insult to the DNA. In both cases, Mad2 foci persisted longer than usual at kinetochores, suggesting a defect in kinetochore-microtubule attachment. In pot1Δ rqh1-hd double mutants and rqh1-hd single mutants released from DNA replication block, SAC-dependent prometaphase arrest was suppressed by the removal of the recombination or replication intermediates. Our results indicate that the accumulation of recombination or replication intermediates induces SAC-dependent prometaphase arrest, possibly by affecting kinetochore-microtubule attachment.
Mesh Terms:
Animals, Cell Cycle Proteins, Chromosome Segregation, Chromosomes, Fungal, DNA Repair, DNA, Ribosomal, Genes, cdc, Kinetochores, M Phase Cell Cycle Checkpoints, Mitosis, Mutation, Rad51 Recombinase, Schizosaccharomyces, Schizosaccharomyces pombe Proteins, Spindle Apparatus, Telomere
Mol. Cell. Biol.
Date: Apr. 01, 2014
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