Project description:Bromodomain proteins (BRD) are key chromatin regulators of genome function and stability, as well as therapeutic targets in cancer. In our associated publication (doi:10.1101/gad.331231.119) we systematically delineate the contribution of human BRD proteins for genome stability and DNA double-strand break (DSB) repair using cell-based assays and proteomic interaction network analysis. These AP-MS experiments were performed in order to construct a protein interaction network for the 24 BRDs we identified as promoters of DNA repair and/or genome integrity: BAZ1B, BRD1, BRD2, BRD3, BRD4, BRD8, BRD9, BRPF3, BRWD3, CECR2, EP300, GCN5/KAT2A, PCAF/KAT2B, PHIP, SMARCA2, SP100, SP110, SP140, TAF1, TRIM24, TRIM28, TRIM33, TRIM66, ZMYND8. In combination with cell based assays, we identified a BRD-reader function of PCAF that bound TIP60-mediated histone acetylations at DSBs to recruit a DUB complex to deubiquitylate histone H2BK120, to allow direct acetylation by PCAF and repair of DSBs by homologous recombination. We also discovered the bromo-and-extra-terminal (BET) BRD proteins, BRD2 and BRD4, as negative regulators of transcription-associated RNA-DNA hybrid (R-Loop) as inhibition of BRD2 or BRD4 increased R-loop formation, which generated DSBs. These breaks were reliant on Topoisomerase II and BRD2 directly bound and activated Topoisomerase I, a known restrainer of R-loops. Thus, comprehensive interactome and functional profiling of BRD proteins revealed new homologous recombination and genome stability pathways, providing a strategy to understand genome maintenance by BRD proteins and the effects of their pharmacological inhibition. This accession provides AP-MS experiment files for the following subset of 18 BRDs: BAZ1B, BRD1, BRD2, BRD3, BRD4, BRD8, BRPF3, BRWD3, CECR2, PHIP, SMARCA2, SP100, SP110, TAF1, TRIM24, TRIM33, TRIM66, ZMYND8, as well as their associated controls (Input, Mock, and SBP-tagged NLS).
2019-12-12 | PXD016700 | Pride
Marjorie Fournier 
