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Live Cell Imaging to Assess the Dynamics of Metaphase Timing and Cell Fate Following Mitotic Spindle Perturbations
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Excess TPX2 Interferes with Microtubule Disassembly and Nuclei Reformation at Mitotic Exit

Francesco D Naso1, Valentina Sterbini1, Elena Crecca1

  • 1Institute of Molecular Biology and Pathology, National Research Council of Italy, c/o Sapienza University of Rome, Via degli Apuli 4, 00185 Rome, Italy.

Cells
|February 12, 2020
PubMed

Insights

Overexpressing microtubule-associated protein TPX2 in non-cancerous cells causes mitotic defects. Its interaction with Aurora-A kinase exacerbates spindle issues, while independent effects disrupt nuclear reformation, leading to abnormal cell shapes.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Cytoskeleton Dynamics

Background:

  • Microtubule-associated protein TPX2 is crucial for mitotic spindle assembly.
  • TPX2 regulates Aurora-A kinase activity and localization.
  • TPX2 overexpression is linked to tumors, but its effects in non-transformed cells are unclear.

Purpose of the Study:

  • Investigate TPX2 overexpression effects in non-transformed hTERT RPE-1 cells.
  • Differentiate effects dependent and independent of Aurora-A interaction.
  • Characterize consequences on mitotic progression and interphase reformation.

Main Methods:

  • Overexpression of full-length and truncated TPX2 (Aurora-A binding deficient) in hTERT RPE-1 cells.
  • Analysis of mitotic spindle assembly and progression.
  • Assessment of microtubule stability and nuclear envelope reformation.

Main Results:

  • TPX2 overexpression causes mitotic spindle defects and delays progression through mitosis.
  • These defects are more severe when TPX2 interacts with Aurora-A.
  • An Aurora-A-independent phenotype shows stable microtubules hindering nuclear reconstitution and lamin B1 network formation, resulting in "doughnut-shaped" nuclei.

Conclusions:

  • Abnormally high TPX2 levels disrupt microtubule cytoskeleton remodeling during mitosis.
  • TPX2's interaction with Aurora-A significantly impacts spindle assembly.
  • TPX2 overexpression can lead to aberrant nuclear reformation and altered cell morphology post-mitosis, independent of Aurora-A.
Keywords:
TPX2mitosisnuclear envelopespindle

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