• Otávio Santiago

CRISPR Screen and Deep Sequencing Map DNA Repair Landscape Boosting Genome Editing Prospects

Updated: Nov 4, 2021

Many powerful genome editing approaches must create breaks across both strands of the DNA double helix and rely on the cell’s own DNA repair machinery to introduce desired changes in the sequence. If a cell fails to repair these DNA double-strand breaks (DSBs) efficiently and accurately, the genome becomes unstable, and the cell dies.

Cells have evolved two pathways to repair DSBs called non-homologous end joining (NHEJ) and homology-directed repair (HDR) with unique genetic components. Yet, how a cell decides to repair DSBs and the factors involved remain unclear.

To enable a better understanding of DSB repair, scientists have now developed a new approach called Repair-seq that pairs CRISPR-based genetic screens with DNA-site-specific deep sequencing to profile the range of mutations produced at targeted DNA sites by different genome editing tools. This new approach helps to understand how DNA repair pathways work to introduce programmable changes in the DNA sequence.

The study, conducted in the laboratories of Britt Adamson, PhD, assistant professor at the department of molecular biology at Princeton, Jonathan Weissman, PhD, professor of biology at the Massachusetts Institute of Technology and an investigator with the Howard Hughes Medical Institute, and Cecilia Cotta-Ramusino, PhD, formerly at Editas Medicine and currently vice president of technology development at Tessera Therapeutics, is published in an article in the journal Cell, titled, “Mapping the Genetic Landscape of DNA Double-strand Break Repair.”

Rodolphe Barrangou, PhD, Distinguished Professor of Food, Bioprocessing and Nutrition Science at the North Carolina State University and the chief editor of The CRISPR Journal, who is not involved in the study comments, “This study critically addresses the second of two parts for genome editing: CRISPR has rendered specific targeting and cleavage straightforward, so the key challenge is now to truly understand the diversity of repair pathways and outcomes that can be triggered.”

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