The Trim33 ubiquitin ligase limits E2f4-dependent DNA replication [Cut&Run II]
Deregulation of RNA polymerase II (RNAPII) by oncoproteins, such as transcription factor Myc, interferes with DNA replication and is a major source of DNA damage and genomic instability. Ubiquitination is a key pathway controlling RNAPII activity via modification of RNAPII subunits or associated regulatory proteins. We uncover a mechanism for genome maintenance by ubiquitin ligase Trim33 and transcription factor E2f4. We show that Trim33 promotes E2f4 protein turnover, restricting interactions of E2f4 with chromatin and with the Recql DNA helicase. Replicative stress blunts Trim33-dependent regulation, which stimulates Recql recruitment to chromatin and facilitates recovery of DNA synthesis. Deletion of Trim33 triggers chronic recruitment of Recql and accelerates DNA replication under stress, accompanied by compromised DDR signaling and DNA repair. Depletion of Trim33 in Myc-overexpressing cells leads to accumulation of replication-associated DNA damage and delays Myc-driven tumorigenesis. We propose that the Trim33-E2f4-Recql axis provides a mechanism to control DNA replication at transcriptionally active chromatin to maintain genome integrity. Overall design: Cut&Run assay in p19Nras Trim33-KO cells, expressing HA-tagged E2f4-FL, E2f4-deltaC or E2f4-deltaDB