Biology subjects

Varignani, G.

Publications and source records attributed to Varignani, G..

2 recordsLinked to original sources

bioRxiv2025

Breaking new ground into RAD51-BRC repeats interplay in Homologous Recombination

Homologous recombination (HR) is a critical repair pathway involving numerous proteins that ensure error-free DNA double-strand breaks (DSBs) repair. Dysfunction in HR components can compromise genome integrity. Despite advances, many aspects of HR remain poorly understood. Notably, even one of the earliest identified and most critical interactions, between RAD51 and BRCA2, remains incompletely characterized, mainly due to the lack of structural data. This study presents a comprehensive biophysical analysis of the RAD51-BRC repeats interaction, integrating computational and experimental approaches. Starting with assessing the correlation between the binding affinities of individual BRC repeats and their impact on RAD51 disassembly, our investigation extends to larger BRCA2 truncations, offering unprecedented insights into the molecular determinants of RAD51 recognition. As mutations in the BRC repeats impair RAD51 recruitment and are associated with cancer, these results provide a valuable framework for interpreting pathogenic variants and guiding precision medicine therapies. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=93 SRC="FIGDIR/small/688182v1_ufig1.gif" ALT="Figure 1"> View larger version (19K): org.highwire.dtl.DTLVardef@8c5cc9org.highwire.dtl.DTLVardef@11f9066org.highwire.dtl.DTLVardef@14159bdorg.highwire.dtl.DTLVardef@16ac161_HPS_FORMAT_FIGEXP M_FIG C_FIG

biochemistry↗

bioRxiv2025

Computationally-designed aptamers targeting RAD51-BRCA2 interaction inhibit RAD51 nuclear recruitment

The interaction between RAD51 and BRCA2 plays a key role in homologous recombination (HR), a critical DNA repair mechanism essential for the survival of cancer cells. Disrupting this interaction increases the sensitivity of cancer cells to chemotherapeutic agents. Here, we employed in silico methods to design a novel class of aptamers--customized single-stranded oligonucleotides--specifically engineered to bind RAD51. These aptamers were developed with the aim of selectively modulating RAD51s nuclear recruitment and its role in DNA repair processes. The leading candidate displays high affinity for RAD51, competing with BRCA2 for the same interaction site in vitro, as confirmed through biolayer interferometry (BLI) and fluorescence lifetime imaging microscopy (FLIM). We tested the efficacy of the leading aptamer in pancreatic cancer cells and observed that it significantly impedes RAD51 nuclear localization, reduces homologous recombination (HR) efficiency, and increases DNA damage. Critically, our aptamer potentiates the cytotoxicity of the PARP inhibitor olaparib, exploiting synthetic lethality (SL) to induce cancer cell death. Our study showcases an aptamer-based approach for selectively targeting protein interactions within DNA repair pathways, introducing a promising avenue for SL-based treatments applicable to a wide range of cancers.

biochemistry↗