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Control of localization of a spindle checkpoint protein, Mad2, in fission yeast

Amy E Ikui1, Kanji Furuya, Mitsuhiro Yanagida

  • 1Department of Radiation Oncology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA.

Journal of Cell Science
|April 16, 2002
PubMed

Insights

The spindle checkpoint uses Mad2 to prevent premature sister chromatid separation by targeting Slp1. Mad2-Slp1 complexes assemble at unattached kinetochores, dissociating upon spindle attachment.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Genetics

Background:

  • The spindle checkpoint ensures accurate chromosome segregation by delaying cell cycle progression.
  • Mad2 protein is a key component of the spindle checkpoint, inhibiting Slp1 (or its homologs) to prevent sister chromatid separation.
  • Mad2 localizes to unattached kinetochores and is crucial for checkpoint activation.

Purpose of the Study:

  • To visualize the Mad2-Slp1 complex and its localization during the cell cycle in fission yeast (Schizosaccharomyces pombe).
  • To investigate the role of unattached kinetochores in the assembly and regulation of the Mad2-Slp1 complex.
  • To explore the interphase localization of Mad2 and the influence of Mad1 on this localization.

Main Methods:

  • Live-cell imaging and protein localization studies in Schizosaccharomyces pombe.
  • Analysis of Mad2 and Slp1 complex formation and dissociation.
  • Examination of Mad2 localization in wild-type and Mad1-deficient yeast strains.

Main Results:

  • The Mad2-Slp1 complex is stable and colocalizes to unattached kinetochores during prometaphase arrest.
  • The Mad2-Slp1 complex is undetectable, and only Mad2 remains associated with the spindle after complete spindle attachment.
  • During interphase, Mad2 localizes to the nuclear periphery and chromatin, a localization dependent on Mad1.

Conclusions:

  • Unattached kinetochores serve as assembly sites for the Mad2-Slp1 complex, which is regulated by spindle attachment.
  • Mad1 plays a critical role in anchoring Mad2 to the nuclear membrane and controlling its nuclear entry during interphase.

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