The role of histone modifications in transcription regulation upon <scp>DNA</scp> damage

Cells are constantly exposed to various sources of DNA damage, including radiation, chemicals, replicative stress and oxidative stress, that threaten genome stability. To ensure faithful DNA repair, transcription regulation needs to be tightly controlled. This regulation involves transcriptional suppression, selective activation of DNA repair-related genes and transcriptional recovery post-repair. Failure to properly modulate transcription during DNA damage can result in collisions between transcriptional and repair machineries, misregulation of repair genes and delayed recovery, ultimately compromising genomic integrity. Chromatin modifications play a central role in this process. These modifications include phosphorylation, methylation, acetylation and ubiquitination, which orchestrate DNA accessibility for repair machinery and fine-tune transcriptional responses. Absence of these modifications leads to inefficient DNA repair and transcriptional errors that are implicated in diseases such as cancer, premature ageing and neurodegenerative disorders. In this review, we delve into the role of various types of histone modifications, such as phosphorylation, methylation, acetylation and ubiquitination and how they regulate transcription in response to DNA damage. Impact Statement This review elucidates how histone modifications orchestrate transcription regulation during DNA damage response, safeguarding genome stability. We also discuss transcription dysregulation in diseases such as cancer and premature aging. Our review provide insights on chromatin-based repair pathways and guide researchers in developing therapeutic targets.