The role of BRIP1 in the maintenance of genomic stability

BRIP1 is a DEAH helicase that has been shown to interact with the breast cancer-associated protein BRCA1 and be involved in BRCA1-dependent double strand DNA break repair and cell-cycle checkpoint control. To study the function of BRIP1 in DNA repair and genomic stability I have generated a targeted disruption of BRIP1 in the chicken DT40 cell line. I have found that brip1 mutant cells, in contrast to brac1 mutant cells, are profoundly sensitive to the DNA cross-linking agent cisplatin, do not have a defect in homologous recombination and show a robust cell-cycle arrest after cisplatin treatment. Furthermore, expression of a human BRIP1 protein that lacks the BRCA1-interacting region is able to fully complement the DNA repair defect of brip1 mutant cells, challenging the view that BRIP1 and BRCA1 function together. In fact the phenotype of brip1 mutant DT40 cells more closely resembles that of cells defective in Fanconi anaemia (FA) proteins, which are involved specifically in the repair of DNA cross-links. Further genetic analysis of the brip1 mutant cells shows that BRIP1 functions in the FA pathway downstream of FANCD2 mono-ubiquitination and is therefore a good candidate for the as yet unidentified FANCJ protein.EThOS - Electronic Theses Online ServiceGBUnited Kingdo