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The mutagenic repair of Cas9 generated breaks is thought to predominantly rely on non-homologous end-joining (NHEJ), leading to insertions and deletions within DNA that culminate in gene knock-out (KO). In this study, by taking focused as well as genome-wide approaches, we show that this pathway is dispensable for the repair of such lesions. Genetic ablation of NHEJ is fully compensated for by alternative end joining (alt-EJ), in a POLQ-dependent manner, resulting in a distinct repair signature with larger deletions that may be exploited for large-scale genome editing. Moreover, we show that cells deficient for both NHEJ and alt-EJ were still able to repair CRISPR-mediated DNA double-strand breaks, highlighting how little is yet known about the mechanisms of CRISPR-based genome editing.
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http://dx.doi.org/10.1038/s41598-019-52078-9 | DOI Listing |
DNA Repair (Amst)
August 2025
Department of Molecular Genetics, Erasmus MC Cancer Institute, Erasmus University Medical Center, Rotterdam, the Netherlands; Department of Vascular Surgery, Erasmus University Medical Center, Rotterdam, the Netherlands; Department of Radiotherapy, Erasmus MC Cancer Institute, Erasmus University Med
DNA crosslink-inducing drugs are widely used in clinical settings for treatment of solid tumors. Double strand breaks (DSBs) that arise during interstrand crosslink (ICL) repair are crucial determinants of the therapeutic response, as they lead to cell death if not repaired. DSBs can be repaired through non-homologous end joining (NHEJ), theta-mediated end joining (TMEJ), and homologous recombination (HR).
View Article and Find Full Text PDFGenes Immun
September 2025
Department of Microbial Infection and Immunity, The Ohio State University, Columbus, OH, USA.
Double-strand breaks represent the most dangerous form of DNA damage, and in resting cells, these breaks are sealed via the non-homologous end joining (NHEJ) factor Ligase IV (LIG4). Excessive NHEJ may be genotoxic, necessitating multiple mechanisms to control NHEJ activity. However, a clear mechanism of transcriptional control for them has not yet been identified.
View Article and Find Full Text PDFAgeing Res Rev
September 2025
Fondazione Policlinico Universitario "A. Gemelli" IRCCS, Rome, Italy; Department of Medicine and Surgery, LUM University, Casamassima, Italy. Electronic address:
Cell Death Differ
September 2025
MOE Key Laboratory of Gene Function and Regulation, Guangdong Province Key Laboratory of Pharmaceutical Functional Genes, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China.
DNA damage response (DDR) is a complicated network that responds to DNA lesions to prevent their accumulation; a defective DDR is one hallmark of cancer. Although targeting DDR pathways has been considered as a therapeutic approach, DDR inhibitors have also been reported ineffective for treating some low mutation burden cancers, such as Mixed-lineage leukemia (MLL)-rearranged (MLL-r) leukemia, a clinically fatal and refractory malignancy. Exploring the roles and mechanisms of DDR pathways in these low mutation burden cancers may help understand the chromatin biology and develop therapeutic strategies.
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