BOA25
Using the Drosophila protein to further our understanding of BRCA2
Rachel Brough, Christopher Lord, Alan Ashworth
Institute of Cancer Research, London, UK
The cancer susceptibility protein BRCA2 regulates RAD51-mediated homologous recombination during double-strand break repair. Loss of functional BRCA2 results in a reduction in gene conversion events along with elevated error-prone single-strand annealing. As a consequence, individuals carrying heterozygous mutations of the BRCA2 gene are at a significantly increased risk to a range of cancers, including those of the breast.
BRCA2 orthologues have now been found in a broad range of organisms, however is poorly conserved through evolution. Nonetheless, conservation between certain motif sequences such as the BRC repeats (for RAD51 binding), nuclear localisation signals and DNA/protein interacting sites, has facilitated the identification of BRCA2 orthologues. The Drosophila melanogaster BRCA2 protein (dmbrca2; CG30169) was first identified by BRC motif sequence similarity and we have recently confirmed it as a true functional orthologue by validating it has a role in DNA repair. The minimal 947aa dmBRCA2 protein contains 3 BRC repeats and lacks a DNA/Dss1 binding domain, which was a region previously thought to be essential for BRCA2 binding at the site of DNA damage.
Here we show that despite lacking this region dmBRCA2 is capable of restoring DNA repair-related function in BRCA2 deficient human CAPAN-1 cells. We also demonstrate how the conservation of dmBRCA2 function can facilitate the analysis of this key DNA repair protein by identifying a novel BRCA2 interacting protein whose connection is validated in the human model. Furthermore, knockdown of expression of this protein causes BRCA-like phenotypes.
