<b>Polymorphisms of canine BRCA2 BRC repeats affecting interaction with </b><b>RAD51 </b>

Abstract

Mutations in the breast cancer susceptibility gene BRCA2 leading to the failure of interactions with the recombinase RAD51 are associated with an increased risk of cancer in humans. This interaction depends on the eight BRC repeat (BRC1-8) sequences in BRCA2. We previously reported that canine BRC3 has two polymorphisms (T1425P and K1435R) influencing the interaction with RAD51, and 1435R was identified in mammary tumor dog samples. In this study, we investigated the sequence variations of BRC3 and 4 in 236 dogs of five breeds. Allele frequencies of 1425P and 1435R were 0.063 and 0.314, respectively, and there was no other polymorphism in the sequenced region. A mammalian two-hybrid assay using BRC3-4 sequences demonstrated that 1425P allele reduced the binding strength with RAD51 but 1435R had no effect. These results may provide an insight into the functions of not only individual but also multiple BRC repeats of BRCA2 in dogs.In humans, the predisposition to heritable breast and ovarian cancers is associated with mutations in the breast cancer susceptibility gene BRCA2 (7). The BRCA2 protein plays an important role in the homologous recombination repair (HR) of doublestranded DNA breaks (DSBs) (7) and promotes the assembly of RAD51 recombinase onto single-stranded DNA (6). To initiate DSB repair by HR, BRCA2 interacts with RAD51 at the highly conserved BRC repeats (BRC) of BRCA2, which consist of 13 conserved amino acid (aa) residues (1). Among eight BRC repeats (BRC1-8), BRC3 and BRC4 are two best-characterized ones exhibiting strong interaction with RAD51 (10,18,21). Mammary tumors are the most common neoplasia in female dogs, and are highly prevalent in certain dog breeds (17). It has been reported that BRCA2 mutations are associated with the development of mammary tumors in dogs (4, 12). We cloned and sequenced canine BRCA2 and found polymorphisms in the putative functional regions containing BRC repeats and nuclear localization signals

Somatic SNPs of the BRCA2 gene at the fragments encoding RAD51 binding sites of canine mammary tumors

“…The BRCA2 protein plays an important role in the HR repair of DSBs and promotes the assembly of RAD51 recombinase onto single‐stranded DNA. To initiate DSB repair by HR, BRCA2 interacts with RAD51 at the highly conserved BRC repeats of BRCA2 , which consist of 13 conserved amino acid residues . Until now, there is limited information available about the genetic variation in BRCA2 gene RAD51 binding/interaction sites in dogs .…”

“…To initiate DSB repair by HR, BRCA2 interacts with RAD51 at the highly conserved BRC repeats of BRCA2 , which consist of 13 conserved amino acid residues . Until now, there is limited information available about the genetic variation in BRCA2 gene RAD51 binding/interaction sites in dogs . Studying the interaction between canine BRC repeats and RAD51 may extend our knowledge of the DNA repair and tumor suppressor roles of BRCA2 …”

“…Among 28 SNPs in this study, c.1828A>C was found in the BRC1 region, whereas c.2383A>C and c.2414G>A had been determined in the BRC3 region. Among eight BRC repeats in BRCA2 gene (BRC1–8), BRC3 and BRC4 are two best‐characterized ones exhibiting strong interaction with RAD51 …”

“…It has been reported that BRCA2 mutations are associated with the development of mammary tumors in dogs . The canine BRCA2 cDNA is 11 kb in length and encodes 3471 amino acids .…”

Canine REIC/Dkk-3 interacts with SGTA and restores androgen receptor signalling in androgen-independent prostate cancer cell lines

“…The cells were harvested 48 h after transfection, and the luciferase activity was measured using the dual-luciferase reporter assay system (Promega). The luciferase activity was normalized to the value of the Renilla luciferase activity [21]. …”