Julio, L. R.; Turrieta Vejar, D. V.; Walborsky, C. H.; Salpukas, A.; Chee, E.; Murthy, J. C.; MacLeod, S. G.; Vandeuren, A. L.; Ferguson, M.; Muriph, R. E.; Evans, J. J.; Day, T. A.

DNA G quadruplexes (G4s) are secondary structures with critical roles in regulating genome function. G4s in regulatory regions like promoters and enhancers are important for controlling gene expression, while aberrant formation of G4s has been linked to genomic instability and human disease. Despite G4s importance and inherent danger, their dynamic formation remains incompletely understood. Here, we show that ultraviolet (UV) radiation uniquely induces widespread and persistent G4 formation in human cells, distinguishing it from other genotoxins. Through integrated genomic, transcriptomic, and proteomic analyses, we uncovered key features and functions of UV-induced G4s. Proteomic profiling identified RCOR3 as a factor associated with specific UV-induced G4s at late time points. Functional studies revealed that RCOR3 is essential for the formation and persistence of these structures. Furthermore, genes associated with UV G4s that are differentially expressed are enriched in pathways related to response to UV radiation, highlighting their biological relevance. These findings define the multi-omic landscape of UV-induced G4s and reveal new mechanistic insights into the interplay between genotoxic stress responses and the regulation of non-canonical DNA structures.