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Interaction between BRCA2 and replication protein A is compromised by a cancer-predisposing mutation in BRCA2
Johnson M S Wong1, Daniela Ionescu, C James Ingles
1Banting and Best Department of Medical Research, University of Toronto, Toronto, Ontario, Canada M5G 1L6.
Oncogene
|January 16, 2003
Summary
The BRCA2 protein
Area of Science:
- Molecular Biology
- Genetics
- Cancer Research
Background:
- Mutations in BRCA1 and BRCA2 genes increase risk for familial, early-onset breast cancer.
- BRCA1 and BRCA2 proteins are involved in DNA double-strand break repair via homologous recombination.
- These proteins also play a role in transcription regulation by RNA polymerase II.
Purpose of the Study:
- To investigate the interaction between BRCA2 and Replication Protein A (RPA).
- To determine if this interaction is biologically significant for DNA repair or transcription.
Main Methods:
- Protein affinity chromatography was used to identify interacting partners of BRCA2.
- Coimmunoprecipitation assays were performed to confirm interactions in vitro and in vivo.
- The effect of a cancer-predisposing mutation (Y42C) on the BRCA2-RPA interaction was assessed.
Main Results:
- The N-terminal transcriptional activation domain of BRCA2 directly interacts with human RPA.
- This interaction is independent of DNA and specific to human RPA.
- A cancer-associated mutation in BRCA2 (Y42C) significantly weakened this interaction.
- BRCA2 and RPA were found to coimmunoprecipitate from HeLa cell extracts, indicating an in vivo interaction.
Conclusions:
- The interaction between BRCA2 and RPA, mediated by BRCA2's transcriptional activation domain, suggests a role in DNA repair.
- This finding implies that the transcriptional activation domains of BRCA2, and potentially BRCA1, may function as a link to RPA and DNA repair pathways, rather than solely transcription.