Editing Primary transcript (section)

===Transcription stress===

[[DNA damage (naturally occurring)|DNA damages]] arise in each cell, every day, with the number of damages in each cell reaching tens to hundreds of thousands, and such DNA damages can impede primary transcription.<ref name = Milano2024>{{cite journal |vauthors=Milano L, Gautam A, Caldecott KW |title=DNA damage and transcription stress |journal=Mol Cell |volume=84 |issue=1 |pages=70–79 |date=January 2024 |pmid=38103560 |doi=10.1016/j.molcel.2023.11.014 |url=}} {{CC-notice|cc=by4}}</ref>  The process of [[gene expression]] itself is a source of endogenous DNA damages resulting from the susceptibility of single-stranded DNA to damage.<ref name = Milano2024/>  Other sources of DNA damage are conflicts of the primary transcription machinery with the [[DNA replication]] machinery, and the activity of certain enzymes such as [[topoisomerase]]s and [[base excision repair]] enzymes.  Even though these processes are tightly regulated and are usually accurate, occasionally they can make mistakes and leave behind DNA breaks that drive [[chromosomal rearrangement]]s or [[cell death]].<ref name = Milano2024/>