Identification of a BRCA1-mRNA splicing complex required for efficient DNA repair and maintenance of genomic stability.
Bottom Line: Mutations within BRCA1 predispose carriers to a high risk of breast and ovarian cancers.Here, we report the identification of a DNA damage-induced BRCA1 protein complex containing BCLAF1 and other key components of the mRNA-splicing machinery.Interestingly, mutations in a number of proteins found within this complex have been identified in numerous cancer types.
Affiliation: Centre for Cancer Research and Cell Biology, Queen's University Belfast, 97 Lisburn Road, Belfast BT9 7BL, UK. Electronic address: email@example.com.Show MeSH
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Mentions: Taken together, our data suggest a model in which phosphorylated BRCA1, bound at a subset of gene promoters following DNA damage, recruits BCLAF1 and associated spliceosomal proteins, thereby facilitating DNA damage-induced mRNA splicing. To confirm that BRCA1, bound at the ATRIP, BACH1, and EXO1 promoters, is indeed phosphorylated at serine-1423 following DNA damage, we performed ChIP-qRT-PCR with BRCA1pSer-1423 antibodies. This revealed marked enrichment of BRCA1pSer-1423 at the ATRIP, BACH1, and EXO1 promoters only following DNA damage (Figure 5A). Also in support of this model, reconstitution of BRCA1 mutant cells (HCC1937) with wild-type BRCA1 restored their ability to upregulate ATRIP, BACH1, and EXO1 mRNA splicing following DNA damage, whereas reconstitution with BRCA1S1423A phosphomutant protein did not (Figures 5B–5D). Additionally, wild-type BRCA1 was able to recruit BCLAF1 to the ATRIP, BACH1, and EXO1 promoter regions following DNA damage, whereas the BRCA1S1423A phospho mutant was not (Figures 5E–5H). Consistent with this, inhibition of ATM and ATR (mediators of BRCA1S1423 phosphorylation) also abrogated DNA damage-induced ATRIP, BACH1, and EXO1 mRNA splicing and recruitment of BCLAF1 and U2AF65 to their promoters (Figures S6A–S6C).
Affiliation: Centre for Cancer Research and Cell Biology, Queen's University Belfast, 97 Lisburn Road, Belfast BT9 7BL, UK. Electronic address: firstname.lastname@example.org.