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

Akemi Nakano1, Kenta Masuda, Taisuke Hiromoto

  • 1Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, Higashi-Hiroshima, Japan.

Molecular and Cellular Biology
|January 29, 2014
PubMed

Insights

Recombination and replication intermediates trigger cell cycle arrest by disrupting kinetochore-microtubule attachments, as observed in fission yeast mutants. This highlights a novel mechanism linking DNA repair to cell cycle regulation.

Area of Science:

  • Cell Biology
  • Genetics
  • Molecular Biology

Background:

  • The spindle assembly checkpoint (SAC) prevents premature anaphase by monitoring kinetochore-microtubule attachments.
  • Pot1Δ and rqh1-hd mutants in fission yeast accumulate DNA recombination and replication intermediates.
  • These intermediates can potentially interfere with cell cycle progression.

Purpose of the Study:

  • To investigate the role of recombination and replication intermediates in SAC-dependent cell cycle arrest.
  • To determine if these intermediates affect kinetochore-microtubule attachment and SAC function.

Main Methods:

  • Generating and analyzing fission yeast mutants (pot1Δ, rqh1-hd, and double mutants).
  • Observing SAC-dependent prometaphase arrest frequency.
  • Assessing Mad2 localization at kinetochores.
  • Manipulating recombination and replication intermediates.

Main Results:

  • pot1Δ rqh1-hd double mutants exhibit increased SAC-dependent prometaphase arrest compared to rqh1-hd single mutants.
  • rqh1-hd mutants show enhanced arrest after DNA replication block.
  • Persistent Mad2 foci at kinetochores suggest impaired kinetochore-microtubule attachment.
  • Removal of intermediates suppressed the SAC arrest.

Conclusions:

  • Accumulation of recombination or replication intermediates induces SAC-dependent prometaphase arrest.
  • This arrest is likely mediated by defects in kinetochore-microtubule attachment.
  • DNA repair intermediates can directly impact cell cycle checkpoint function.

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