BRCA1/BARD1 Orthologs Required for DNA Repair in Caenorhabditis elegans

Inherited germline mutations in the tumor suppressor gene BRCA1 predispose individuals to early onset breast and ovarian cancer. BRCA1 together with its structurally related partner BARD1 is required for homologous recombination and DNA double-strand break repair, but how they perform these functions remains elusive. As part of a comprehensive search for DNA repair genes in C. elegans, we identified a BARD1 ortholog. In protein interaction screens, Ce-BRD-1 was found to interact with components of the sumoylation pathway, the TACC domain protein TAC-1, and most importantly, a homolog of mammalian BRCA1. We show that animals depleted for either Ce-brc-1 or Ce-brd-1 display similar abnormalities, including a high incidence of males, elevated levels of p53-dependent germ cell death before and after irradiation, and impaired progeny survival and chromosome fragmentation after irradiation. Furthermore, depletion of ubc-9 and tac-1 leads to radiation sensitivity and a high incidence of males, respectively, potentially linking these genes to the C. elegans BRCA1 pathway. Our findings support a shared role for Ce-BRC-1 and Ce-BRD-1 in C. elegans DNA repair processes, and this role will permit studies of the BRCA1 pathway in an organism amenable to rapid genetic and biochemical analysis.