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Aurora B is required for mitotic chromatin-induced phosphorylation of Op18/Stathmin

Bedrick B Gadea1, Joan V Ruderman

  • 1Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA.

Proceedings of the National Academy of Sciences of the United States of America
|March 16, 2006
PubMed

Insights

Aurora B kinase regulates Oncoprotein 18/Stathmin (Op18) phosphorylation during mitosis. This finding is crucial for understanding microtubule dynamics and spindle assembly, impacting cell division processes.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • Oncoprotein 18/Stathmin (Op18) is a key microtubule-destabilizing protein.
  • Op18 activity is regulated by phosphorylation, particularly during mitosis.
  • Mitotic chromosomes are required for Op18 hyperphosphorylation, suggesting a role for chromosome-associated kinases.

Purpose of the Study:

  • To investigate the role of Aurora A (Aur-A) and Aurora B (Aur-B) kinases in the regulation of Op18 phosphorylation.
  • To determine if Aur-A or Aur-B are involved in the chromosome-dependent hyperphosphorylation of Op18.

Main Methods:

  • Utilized Xenopus egg extracts to study Op18 phosphorylation.
  • Employed the Aurora kinase inhibitor ZM447439 (ZM).
  • Performed Aur-B and Aur-A depletion experiments and analyzed Op18 phosphorylation status.

Main Results:

  • ZM treatment inhibited the ability of mitotic chromatin to induce Op18 hyperphosphorylation.
  • Depletion of Aur-B, but not Aur-A, abolished Op18 hyperphosphorylation.
  • Chromatin assembled without Aur-B failed to induce Op18 hyperphosphorylation.

Conclusions:

  • Aurora B kinase plays a significant role in the localized regulation of Op18 during spindle assembly.
  • Aur-B, concentrated at centromeres, contributes to the control of microtubule dynamics via Op18 phosphorylation.

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