BRD4 Prevents R-Loop Formation and Transcription-Replication Conflicts by Ensuring Efficient Transcription Elongation
57 Pages Posted: 12 Dec 2019 Publication Status: Published
More...Abstract
Effective spatio-temporal control of transcription and replication during S-phase is paramount to maintain genomic integrity and cell survival. Deregulation of these systems can lead to conflicts between the transcription and replication machinery leading to DNA damage. BRD4, a BET bromodomain protein and known transcriptional regulator, interacts with P-TEFb to ensure efficient transcriptional elongation by stimulating phosphorylation of RNA Polymerase II (RNAPII). Here we report that disruption of BET bromodomain protein function causes DNA damage that correlates with RNAPII-dependent transcript elongation and occurs preferentially in S-phase cells. BET bromodomain inhibition also causes accumulation of RNA:DNA hybrids (R-loops), which are known to lead to transcription-replication conflicts, DNA damage, and cell death. Furthermore, we show that resolution of R-loops abrogates BET-bromodomain inhibitor-induced DNA damage, and that BET-bromodomain inhibition induces both R-loops and DNA damage at sites of BRD4 occupancy. Finally, we show that the BRD4 C-terminal domain, which interacts with P-TEFb, is required to prevent R-loop formation and DNA damage caused by BET bromodomain inhibition. Together, these findings demonstrate that BET bromodomain inhibitors can damage DNA via induction of R-loops in highly replicative cells.
Keywords: BRD4, R-loops, Transcription-Replication Conflicts, DNA damage, Replication Stress, Cancer, BET Bromodomain
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