The Functions of BRCA2 in Repairing DNA Damage
Creators: name: University Of California Office Of The President
Publisher: name: University of California Office of the President
publisherIdentifier: https://ror.org/00dmfq477
publisherIdentifierScheme: ROR
Year: 2024

description: Breast cancer is the most common malignancy among women worldwide, and its incidence is increasing. The discovery of the breast cancer genes, BRCA1 and BRCA2 about six years ago promised to open new doors to understanding the disease. However, exactly how loss of the functions of these two genes causes predisposition to breast cancer has remained elusive. The work proposed here is directed toward answering this question for BRCA2.
 
 
 
 
 
 
 
 Living cells possess sophisticated mechanisms for repairing damage to their DNA. Recent evidence has indicated that the BRCA2 protein plays a role in a specific type of DNA repair mechanism known as "homologous recombinational repair" (HRR). This repair process utilizes the information provided by the complimentary DNA strand to restore a break and is thought to be an error-free repair. The Rad51 protein is a central player, which with the help of other proteins, such as BRCA2, promotes the key reaction required for HRR. Thus, when the BRCA2’s functions become impaired, the HRR mechanism becomes defective. DNA damage begins to accumulate in the cell's genes and can finally result in uncontrolled cell growth. Therefore, dysfunction of the DNA repair pathway may be a general phenomenon in the major cases of hereditary breast cancer. We will provide direct experimental evidence for the functions of BRCA2 in HRR.
 
 
 
 
 
 
 
 Recent evidence supports a concept that a multiprotein complex involving Rad51 and five Rad51-related proteins may operate as a functional unit in regulating HRR. We hypothesize that the BRCA2 protein participates directly in HRR through physical interaction with the key protein Rad51, such that loss of the BRCA2-Rad51 interaction suppresses HRR. We further hypothesize that the BRCA2 protein is an essential component of this HRR complex functioning to directly regulate the biochemical activities of Rad51. The aims of this project are: 
 
 
 
 
 
 
 
 1. Using cellular approaches, we will test whether the BRCA2 protein directly regulates HRR by modifying a human cell line so that they carry an artificial 'reporter' gene. The reporter gene will allow us to measure recombination activity with and without disruption of the BRCA2-Rad51 interaction.
 
 
 
 
 
 
 
 2. Using protein biochemistry approaches, including a novel baculovirus co-expresssion strategy, enzyme activity assays, protein binding experiments, and special chromatography, we propose to demonstrate the functions of BRCA2 in controlling the actions of Rad51, and the formation of a stable HRR complex involving BRCA2 and Rad51.
 
 
 
 
 
 
 
 The demonstration of the functions of BRCA2 in HRR would be an important step toward elucidating the mechanism underlying the pathogenesis of BRCA2-mediated breast cancer. Also, we would get important clues to the role of HRR in sporadic breast cancer. Such an understanding would reveal new targets for prognostic interpretation and therapeutic intervention in breast cancer.