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Tpr directly binds to Mad1 and Mad2 and is important for the Mad1-Mad2-mediated mitotic spindle checkpoint

Sang Hyun Lee1, Harry Sterling, Alma Burlingame

  • 1Helen Diller Family Comprehensive Cancer Center, University of California at San Francisco, San Francisco, California 94115, USA.

Genes & Development
|November 5, 2008
PubMed

Insights

The translocated promoter region (Tpr) protein interacts with Mad1 and Mad2, crucial for cell cycle regulation. Tpr

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Protein Interactions

Background:

  • Mad1 and Mad2 proteins form a complex essential for mitotic arrest when spindle assembly is abnormal.
  • The spindle assembly checkpoint ensures proper chromosome segregation during cell division.

Purpose of the Study:

  • To identify novel proteins interacting with Mad2.
  • To elucidate the role of Tpr in Mad1-Mad2 complex formation and function.
  • To understand Tpr's contribution to mitotic spindle checkpoint signaling.

Main Methods:

  • Mass spectrometry was used to identify Mad2-associated factors.
  • Affinity purification was employed to isolate Mad2-binding proteins.
  • Tpr depletion in HeLa cells was performed to assess its functional impact.

Main Results:

  • Translocated promoter region (Tpr) was identified as a novel Mad2-interacting protein.
  • Tpr directly binds to both Mad1 and Mad2.
  • Tpr depletion disrupts nuclear pore complex localization of Mad1/Mad2, reduces Mad1-Mad2 binding, and impairs kinetochore localization of Mad1, hindering Mad2 activation and APC(Cdc20) inhibition.

Conclusions:

  • Tpr plays a critical role in regulating Mad1-Mad2 protein complex localization and function during the cell cycle.
  • Tpr is essential for proper mitotic spindle checkpoint signaling by facilitating Mad1-Mad2 complex assembly and kinetochore recruitment.

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