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Establishment of Proliferative Tetraploid Cells from Nontransformed Human Fibroblasts
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Crosstalk of the mitotic spindle assembly checkpoint with p53 to prevent polyploidy

Celia Vogel1, Anne Kienitz, Irmgard Hofmann

  • 1Institute for Molecular Biology and Tumor Research, Philipps University Marburg, Emil-Mannkopff-Strasse 2, D-35037 Marburg, Germany.

Oncogene
|August 3, 2004
PubMed

Insights

Cellular polyploidization is prevented by multiple checkpoints, including the spindle assembly checkpoint and a p53-dependent G1 checkpoint. A functional spindle assembly checkpoint is crucial for proper G1 checkpoint function, preventing abnormal cell division.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Genetics

Background:

  • Microtubule inhibitors trigger the mitotic spindle assembly checkpoint, causing mitotic arrest.
  • Prolonged arrest can lead to aberrant mitotic exit and tetraploid cells in G1.
  • These tetraploid cells may arrest in G1 via a p53-dependent pathway, or undergo endoreduplication if this checkpoint fails.

Purpose of the Study:

  • To investigate the roles of p53 and the spindle assembly checkpoint (SAC) in postmitotic G1 checkpoint function.
  • To elucidate the pathways involved in p53 activation during mitotic arrest.
  • To identify mechanisms preventing polyploid cells from re-entering mitosis.

Main Methods:

  • Utilized HCT116 cells and their isogenic derivatives lacking p53 or with compromised spindle assembly checkpoints.
  • Analyzed p53 stabilization and activation pathways during transient and prolonged mitotic arrest.
  • Investigated the G2 checkpoint's role in preventing re-entry into mitosis by polyploid cells.

Main Results:

  • Both p53 and a functional SAC are essential for postmitotic G1 checkpoint control.
  • p53 stabilization and activation during transient mitotic arrest occur independently of ATM/ATR, Chk1, and Chk2.
  • A prolonged SAC-mediated mitotic arrest is necessary for effective G1 checkpoint function.
  • An additional G2 checkpoint inhibits polyploid cells from re-entering mitosis.

Conclusions:

  • The cell cycle employs a multi-layered checkpoint system to prevent polyploidization and aneuploidization.
  • This system includes the mitotic spindle checkpoint, a p53-dependent G1 checkpoint, and a G2 checkpoint.
  • Proper functioning of the SAC is critical for subsequent G1 checkpoint activation and genomic stability.

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