BARD1 recognizes pre-rRNA for DNA damage repair and rRNA biogenesis.

The Breast cancer susceptibility gene 1 (BRCA1)/BRCA1-associated RING domain 1 (BARD1) complex recognizes pre-ribosomal RNA (pre-rRNA) to coordinate the process of double-strand break (DSB) repair. However, the biological functions and molecular mechanisms under this process have not been explained clearly. Here, we find an important pre-rRNA binding site highly conserved among BARD1 proteins. Mutation of this binding site not only disrupts pre-rRNA binding but also impairs homologous recombination (HR) repair. Moreover, we show that BARD1 localizes in the nucleolus and regulates rRNA biogenesis. Loss of BARD1 reduces levels of pre-rRNA and neosynthesized protein. Collectively, this study reveals that BARD1 plays a crucial role in both DSB repair and protein synthesis.