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Cell cycle dependent degradation of MCAK: evidence against a role in anaphase chromosome movement

Anutosh Ganguly1, Rajat Bhattacharya, Fernando Cabral

  • 1Department of Integrative Biology and Pharmacology, University of Texas Medical School, Houston, Texas 77030, USA.

Cell Cycle (Georgetown, Tex.)
|October 10, 2008
PubMed

Insights

Cellular levels of the mitotic centromere-associated kinesin (MCAK) protein peak during G2/M phase and are rapidly degraded by the proteasome during mitosis. This degradation limits MCAK activity in late mitosis, suggesting it does not drive anaphase chromosome movement.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • Mitotic centromere-associated kinesin (MCAK) is a motor protein crucial for spindle assembly and mitotic chromosome alignment.
  • Its microtubule depolymerizing activity is essential for correcting errors during mitosis.

Purpose of the Study:

  • To investigate the regulation of cellular MCAK levels throughout the cell cycle.
  • To determine the role of protein degradation in controlling MCAK activity during mitosis.

Main Methods:

  • Cell cycle analysis to track MCAK protein levels.
  • Immunofluorescence microscopy to visualize MCAK localization.
  • Proteasome inhibition studies.
  • Analysis of MCAK phosphorylation status.

Main Results:

  • MCAK protein levels accumulate during cell cycle progression, peaking at G2/M phase.
  • MCAK is rapidly degraded by the proteasome during mitosis, particularly after the metaphase-anaphase transition.
  • A phosphorylated form of MCAK appears during mitosis and is preferentially degraded.
  • Degradation of MCAK does not appear to depend on Aurora B kinase activity.

Conclusions:

  • MCAK activity is primarily regulated by proteasomal degradation during the later stages of mitosis.
  • The observed degradation pattern argues against a significant role for MCAK in anaphase chromosome movement.
  • Understanding MCAK regulation provides insights into precise cell division mechanisms.

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