A new fluorescence-based sensor now lets researchers watch DNA repair unfold in real time inside living cells. When both strands of the DNA helix snap – a lethal lesion if left unrepaired – the sensor signals the arrival of the MRN complex (MRE11, RAD50, and NBS1 proteins) within seconds. High-resolution movies reveal MRN rapidly resecting the broken ends, generating single-stranded DNA overhangs up to 1,000 nucleotides long in under ten minutes to prepare the site for homologous recombination. Tracking hundreds of individual breaks showed striking variation: some sites resect smoothly and complete repair, while others stall at intermediate steps, hinting that local chromatin environment or break complexity governs outcome. Published in Nature Communications, the work provides the first direct view of this key genome-maintenance process in action.

ARTICLE

da Silva RC, Eleftheriou K, Recchia DC, et al. Engineered chromatin readers track damaged chromatin dynamics in live cells and animals. Nat Commun. 2025;16(1):10127. https://doi.org/10.1038/s41467-025-65706-y

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