Chromatin compartmentalization regulates the response to DNA damage

Area of Science:

• Genomics
• Molecular Biology
• Cell Biology

Background:

• The DNA damage response (DDR) is crucial for maintaining genome integrity.
• While chromatin's role in DNA repair is known, the impact of chromosome folding is less understood.

Purpose of the Study:

• To investigate the role of chromosome folding and compartmentalization in the DNA damage response.
• To characterize the formation and function of a novel chromatin compartment induced by DNA double-strand breaks (DSBs).

Main Methods:

• Induction of DSBs in mammalian cells.
• Analysis of chromatin organization using techniques to detect damaged topologically associating domains (TADs) and specific markers (γH2AX, 53BP1).
• Investigation of the mechanism of compartment formation (polymer-polymer vs. liquid-liquid phase separation) and its regulation.

Main Results:

• ATM signaling drives the formation of a new chromatin compartment (D compartment) by clustering damaged TADs.
• This compartment formation is consistent with polymer-polymer phase separation and occurs primarily in G1 phase.
• The D compartment enhances the activation of R-loop-enriched DNA-damage-responsive genes, but also increases translocation rates.

Conclusions:

• DSB-induced compartmentalization orchestrates the DNA damage response.
• Chromosome architecture plays a critical role in both DNA repair and genomic instability.
• The study reveals a novel mechanism linking chromosome folding to genome maintenance and disease.