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Studying Proteolysis of Cyclin B at the Single Cell Level in Whole Cell Populations
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Studying Proteolysis of Cyclin B at the Single Cell Level in Whole Cell Populations

Published on: September 17, 2012

Cut8, essential for anaphase, controls localization of 26S proteasome, facilitating destruction of cyclin and Cut2

H Tatebe1, M Yanagida

  • 1CREST Research Project, Department of Biophysics, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto, Japan.

Current Biology : CB
|November 21, 2000
PubMed
Abstract

Insights

Cut8 is a heat-inducible protein essential for cell division in fission yeast. It ensures proper chromosome segregation by recruiting the 26S proteasome to the nucleus for timely protein degradation.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Genetics

Background:

  • The anaphase-promoting complex (APC)/cyclosome and 26S proteasome are crucial for cell cycle progression, mediating the degradation of key mitotic proteins.
  • Defects in these complexes lead to failed mitosis, characterized by hypercondensed chromosomes and short spindles.
  • The function of Cut8, a protein implicated in these processes, remains poorly understood.

Purpose of the Study:

  • To elucidate the molecular mechanism of Cut8 function in fission yeast mitosis.
  • To investigate the role of Cut8 in regulating protein degradation and chromosome segregation.

Main Methods:

  • Utilized a temperature-sensitive fission yeast strain (cut8-563) to study Cut8 function at restrictive temperatures.
  • Analyzed protein levels, localization, and cell division phenotypes in wild-type and cut8 mutant cells.
  • Investigated the localization of the 26S proteasome in relation to Cut8.

Main Results:

  • Cut8 levels increase and become essential for anaphase progression at high temperatures.
  • Cut8 mutants exhibit chromosome mis-segregation and abnormal spindle dynamics, but normal cytokinesis.
  • The degradation of mitotic cyclin and Cut2 is delayed in cut8 mutants, despite normal ubiquitination.
  • Cut8 is primarily nuclear, and its absence causes the 26S proteasome to mislocalize to the cytoplasm.

Conclusions:

  • Cut8 is a novel, evolutionarily conserved, heat-inducible regulator of cell division.
  • Cut8 promotes anaphase-specific proteolysis by recruiting the 26S proteasome to the nucleus.
  • Proper nuclear localization of the 26S proteasome, facilitated by Cut8, is essential for efficient mitosis.

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