DNA double strand break repair pathway choice: a chromatin based decision?

Area of Science:

• Molecular Biology
• Genetics
• Epigenetics

Background:

• DNA double-strand breaks (DSBs) are toxic DNA lesions requiring efficient repair.
• Two primary repair pathways exist: Homologous Recombination (HR) and Non-Homologous End Joining (NHEJ).
• The mechanism governing the choice between HR and NHEJ remains incompletely understood.

Purpose of the Study:

• To investigate the role of histone modifications in directing DSB repair pathway choice.
• To propose a generalized model for DSB repair pathway selection based on chromatin features.

Main Methods:

• Analysis of DSB repair pathway usage in relation to specific genomic locations and histone marks.
• Investigation of the role of SETD2, the H3K36 trimethyltransferase, in HR-mediated repair of DSBs in active genes.

Main Results:

• DSBs within active genes, enriched for H3K36me3, are preferentially repaired by HR.
• This HR-dependent repair is dependent on the activity of SETD2.
• These findings suggest a link between specific histone modifications and DSB repair pathway selection.

Conclusions:

• A model termed the "DSB repair choice histone code" is proposed, where histone modifications dictate repair pathway selection.
• Pre-existing chromatin structure plays a critical role in deciding the DSB repair mechanism.
• This regulatory mechanism contributes to maintaining genome stability and potentially genome diversity.