DNA end-resection is stimulated by an interaction between BRCA1 exon 11 and TOPBP1.

Interaction between BRCA1 exon 11 and TOPBP1 is essential for DNA end-resection during homologous recombination.

• Why it matters: Understanding the function of BRCA1 exon 11 is crucial because many tumors have mutations leading to exon skipping, which may impair DNA repair and contribute to cancer progression.
• What they did: Proteomic analyses identified a DNA damage- and phospho-dependent interaction between TOPBP1 and the BRCA1 region encoded by exon 11, revealing a mechanistic role in end-resection.
• The result: This interaction is necessary for BRCA1's function in homologous recombination but not for TOPBP1's role in ATR activation, providing new insights into BRCA1's specific activities.