Cancer-causing BRCA2 missense mutations disrupt an intracellular protein assembly mechanism to disable genome...

Area of Science:

• Molecular biology
• Genetics
• Cancer research

Background:

• Missense mutations in BRCA2 are frequently found in breast and ovarian cancers.
• These mutations often occur in the carboxyl-terminal domain (DBD) of the BRCA2 protein.

Purpose of the Study:

• To identify a common molecular mechanism for pathogenic BRCA2 missense mutations.
• To explore the role of DSS1 in BRCA2 function and pathogenicity.
• To investigate therapeutic strategies for BRCA2-mutated cancers.

Main Methods:

• Analysis of pathogenic and benign BRCA2 mutations in the DBD.
• Investigation of DSS1-BRCA2 protein interactions.
• Assessment of BRCA2 nuclear localization and DNA repair by homologous DNA recombination (HDR).
• Evaluation of DSS1 expression to correct defective HDR.

Main Results:

• Pathogenic BRCA2 mutations cluster in DSS1-binding motifs within the DBD.
• Mutations weaken or abolish DSS1-BRCA2 assembly, leading to nuclear exclusion and impaired HDR.
• DSS1 inhibits wild-type BRCA2 oligomerization but not mutant forms.
• DSS1 expression can rescue HDR defects in cells with partially impaired DSS1-BRCA2 binding.

Conclusions:

• Cancer-causing BRCA2 mutations disrupt a DSS1-mediated protein assembly crucial for DNA repair.
• The findings suggest a therapeutic approach targeting the DSS1-BRCA2 interaction to correct DNA repair deficiencies in BRCA2-mutated cancers.