Figure 2.

R-Loops are regulated via TOP1 and are subject to breakage through endogenous and exogenous mechanisms. Topoisomerase I (TOP I) relieves transcriptionally induced torsional tension and regulates the formation of DNA breaks (blue)/RNA (purple) hybrids (R-loops). The exposed single-strand DNA segment (red) can be harmed via several processes and develops into a DSB (not shown). Endogenously, breaks can occur due to collisions between transcription machinery (RNA Polymerase II, pink) and replication machinery (DNA polymerase, light blue). The DNA can also be damaged via exogenous stresses, such as IR, UV, oxidative stress and other chemicals. Figure was generated using BioRender tool.