Chromatin perturbations during the DNA damage response in higher eukaryotes

Area of Science:

• Molecular Biology
• Cell Biology
• Genetics

Background:

• The DNA damage response (DDR) orchestrates DNA repair, cell cycle checkpoints, and cell death pathways.
• ATM and ATR are apical kinases crucial for signaling DNA damage.
• The chromatin environment plays a complex role in sensing DNA lesions.

Purpose of the Study:

• To investigate the role of chromatin perturbations in the activation of ATM and ATR kinases.
• To identify mechanisms by which chromatin changes facilitate DNA damage signaling and repair.

Main Methods:

• Investigated the activation of ATM kinase by the MRN complex and KAT5 acetyltransferase.
• Examined the role of chromatin decondensation and histone eviction in ATM and ATR activation.
• Identified nucleolin as a histone chaperone involved in nucleosome disruption and DNA repair.

Main Results:

• ATM kinase activation by double-strand breaks (DSBs) requires the MRN complex and KAT5.
• Chromatin decondensation and histone eviction at DSBs facilitate KAT5 binding and ATM activation.
• Nucleolin acts as a histone chaperone for nucleosome disruption at DSBs, aiding repair.
• ATM and ATR kinases are activated by chromatin perturbations, even without direct DSBs.

Conclusions:

• Chromatin perturbations, including decondensation and histone eviction, are a common and critical mechanism for ATM and ATR kinase activation.
• These chromatin alterations are both sufficient and necessary for inducing the DNA damage response.