Phd in HUMAN BIOLOGY AND MEDICAL GENETICS

Thesis title: INVESTIGATING THE ROLE OF WRNIP1 IN THE MAINTENANCE OF GENOME STABILITY

ABSTRACT Maintenance of genome integrity is essential for cell viability and depends on complete and accurate DNA replication. However, G4/R-loops may provide significant obstacles for DNA replication, as they can cause collisions between replication fork and the transcription machinery. Hence, cells require mechanisms to counteract the presence of persistent G4/R-loops, most of which remain poorly understood. Here, we demonstrate an involvement of the Werner helicase-interacting protein 1 (WRNIP1) in preventing DNA damage induced by G4/R-loop-associated transcription-replication conflicts. We discovered that the ubiquitin-binding domain of WRNIP1 is required to efficiently avoid pathological persistence of G4/R-loops upon replication stress. Also, we observed that G4s reside within R-loops and that WRNIP1 colocalises with these structures. Furthermore, WRNIP1 plays a role in restarting replication from transcription-induced fork stalling. More importantly, we characterized the interplay between WRNIP1 and the DNA helicase FANCJ in counteracting R-loop-dependent G4 formation in response to replication stress. Collectively, our findings propose a mechanism whereby WRNIP1, contributing to stabilise FANCJ to G4 sites, mitigates the G4/R-loop-mediated transcription-replication conflicts and protects against DNA damage accumulation.