Advancing safer gene editing

At Tufts, researchers are at the forefront of advancements in gene editing technology. Professor Qiaobing Xu and his team, including research assistant professor and first author Shuliang Gao, of the Department of Biomedical Engineering, recently published work in Nature Communications detailing improvements in CRISPR-Cas9 gene editing. The research, titled “Improving adenine base editing precision by enlarging the recognition domain of CRISPR-Cas9,” offers new insights into enhancing the precision and accuracy of CRISPR-Cas9, a powerful tool for gene editing. This breakthrough could have significant implications for genetic research, therapies, and biotechnology.

CRISPR-Cas9 can be used to edit a genome by inserting, removing, or altering a portion of a DNA strand. The team focused on addressing the long-standing issue of off-target genetic modifications in CRISPR-Cas9 technology, which can compromise the precision and accuracy of gene edits. By expanding the recognition (REC) domain of SpCas9, one of the most widely used Cas9 proteins, they created a larger, more effective version called Giant SpCas9 (GS-Cas9). This expanded protein consists of 1780 amino acids and includes the largest REC domain ever identified, measuring 1036 amino acids. The team demonstrated for the first time that enlarging the non-catalytic REC domain improves the precision of the catalytic domain, significantly reducing unintended alterations during gene editing.

Xu’s research opens up exciting new possibilities for gene-editing advancements. As the team explains in their paper, "Perhaps our exploration will open a gate to create diverse Cas9 variants by enlarging specific domains in the laboratory instead of natural evolution." This innovative approach demonstrates that expanding the Cas9 protein in a targeted way could lead to more precise gene-editing tools. While the increased size of gene editors could present challenges for adeno-associated virus (AAV) delivery, recent advancements show that techniques like lipid nanoparticles (LNPs) can be used to deliver large cargos. The Xu group has a longstanding track record in developing LNPs for organ- and cell-selective delivery. His team will explore potential solutions for delivering such larger gene editors and work to make this approach practical for real-world applications.

The implications of this work are vast. By improving the accuracy of gene-editing technologies like CRISPR-Cas9, Xu’s research has the potential to make gene therapies safer and more effective. These insights into REC-domain expansion also open the door for further research into RNA-guided endonucleases. The study represents a crucial step toward making gene editing a more reliable and precise tool for drug development and optimization, treating genetic disorders, advancing personalized medicine, and driving forward scientific research across various fields.

The co-authors of the paper include Benson Weng, A25, PhD candidates Douglas Wich and Mengting Chen, Liam Power of the Graduate School of Biomedical Sciences, Huiwen Guan, EG24, Research Assistant Professor Zhongfeng Ye, and Chutian Xu, E24.