Abasic site repair in APE1-deficient mouse embryonic stem cells: a matter for the MRN complex and ATM signaling.

APE1 is crucial for mouse embryonic stem cell differentiation, with its absence triggering compensatory DNA repair mechanisms involving NER and TLS pathways.

• Why it matters: Understanding how stem cells maintain genomic and epigenetic stability during active DNA demethylation is vital for insights into development and disease, especially given the complex interplay of repair pathways.
• What they did: Using APE1-deficient mESCs with inducible TDG depletion and a genome-wide CRISPR/Cas9 screen, the study identified that TDG contributes significantly to AP site formation and uncovered unexpected genetic dependencies beyond traditional repair roles.
• The result: Findings reveal that DNA repair pathways exhibit high plasticity, with alternative mechanisms compensating for APE1 loss, which supports genomic integrity and highlights potential targets for modulating stem cell differentiation.