Cloning and sequencing full length of canine Brca2 and Rad51 cDNA

Mammary tumors are the most common neoplasm in female dogs. Canis canis, an d in women. Mutations in human Brca2 confer an increased risk of female bre ast cancer. Previous studies have shown that the Brca2 tumor suppressor pro tein interacts with the recombinational repair protein Rad51. We cloned the full-length cDNA of the canine homologues of Brca2 and Rad51 to obtain a b asis for studying their relationship with susceptibility to mammary tumors. The canine Brca2 and Rad51 cDNAs are 11 and 1.5 kb long, encoding 3,471 an d 339 amino acids, respectively. The amino acid sequence of canine Brca2 sh owed 68% homology with the human protein., and 58% homology with a murine p rotein. There were highly conserved regions in the C-terminus of all three proteins, where the Rad51 interacting domain and putative nuclear localizat ion signals are located. Comparing with the partial genomic sequence previo usly reported, we found possible nuclear polymorphisms in exon 11, some of which result in amino acid substitutions. On the other hand, canine Rad51 p rotein had extremely high homology (99%) to the human and murine proteins. Expression of both Brca2 and Rad51 was detected in the mammary gland, sugge sting that these two genes interact in the canine mammary gland.