An ATM-Chk2-INCENP pathway activates the abscission checkpoint

Area of Science:

• Cell Biology
• Molecular Biology
• Genetics

Background:

• The chromosomal passenger complex (CPC) delays cell division abscission to prevent chromosome breakage.
• Chromatin bridges trigger this delay, but the underlying molecular mechanisms are not fully understood.

Purpose of the Study:

• To elucidate the molecular pathway regulating CPC localization and the abscission checkpoint.
• To identify key kinases and proteins involved in preventing DNA damage during cytokinesis.

Main Methods:

• Inhibition of ATM or Chk2 kinases in cultured human cells.
• Analysis of CPC localization, midbody resolution, and abscission timing.
• Genetic manipulation using truncated or mutated proteins (Mklp2, INCENP).
• Investigating the role of the Mre11-Rad50-Nbs1 complex.

Main Results:

• ATM and Chk2 kinases are crucial for CPC localization to the midbody center.
• Chk2 phosphorylates INCENP, promoting its binding to Mklp2 and subsequent CPC localization.
• Impaired CPC localization accelerates abscission and leads to chromatin breakage.
• The Mre11-Rad50-Nbs1 complex is required for ATM activation at the midbody.

Conclusions:

• An ATM-Chk2-INCENP signaling pathway regulates the abscission checkpoint.
• This pathway ensures proper CPC midbody localization, preventing genomic instability during cell division.