NOMIS researcher Jacob Corn and colleagues have discovered that the enzyme TREX1 hinders the efficiency of CRISPR gene editing in certain cells. By blocking TREX1 or using protected DNA templates, the researchers were able to significantly improve gene editing, offering new strategies to enhance genome editing in challenging contexts. Their findings were published in Nature Biotechnology. Corn is the NOMIS Professor of Genome Biology at ETH Zurich.
Abstract
CRISPR–Cas9-mediated homology-directed repair (HDR) can introduce desired mutations at targeted genomic sites, but achieving high efficiencies is a major hurdle in many cell types, including cells deficient in DNA repair activity. In this study, we used genome-wide screening in Fanconi anemia patient lymphoblastic cell lines to uncover suppressors of CRISPR–Cas9-mediated HDR. We found that a single exonuclease, TREX1, reduces HDR efficiency when the repair template is a single-stranded or linearized double-stranded DNA. TREX1 expression serves as a biomarker for CRISPR–Cas9-mediated HDR in that the high TREX1 expression present in many different cell types (such as U2OS, Jurkat, MDA-MB-231 and primary T cells as well as hematopoietic stem and progenitor cells) predicts poor HDR. Here we demonstrate rescue of HDR efficiency (ranging from two-fold to eight-fold improvement) either by TREX1 knockout or by the use of single-stranded DNA templates chemically protected from TREX1 activity. Our data explain why some cell types are easier to edit than others and indicate routes for increasing CRISPR–Cas9-mediated HDR in TREX1-expressing contexts.
Read the Nature Biotechnology publication: Removal of TREX1 activity enhances CRISPR–Cas9-mediated homologous recombination
Feature image: Overall model of TREX1’s role in repressing CRISPR–Cas9-mediated HDR. (Image: Corn et al., Nature Biotechnology)
