1. Development of a Self-Restricting CRISPR-Cas9 System to Reduce Off-Target Effects
- Author
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Hui Wang, Hua Lu, Ying-shou Lei, Chen-yu Gong, Zhao Chen, Ying-qiao Luan, Qiang Li, Ying-zhen Jian, Hao-zheng Wang, Feng-lin Wu, Chang-li Tao, Han Shen, Hua-ben Bo, Hong-wei Shao, and Wen-feng Zhang
- Subjects
Genetics ,QH426-470 ,Cytology ,QH573-671 - Abstract
Development of the CRISPR-Cas9 gene-editing system has given rise to a new era of gene editing with wide applications in biology, medicine, agriculture, and other fields. However, the overexpression of Cas9 nuclease causes off-target effects and may trigger an immune response in vivo. Therefore, we constructed a self-restricting CRISPR-Cas9 system, where the target gene sequence corresponding to the guide RNA (gRNA) is inserted on either end of the Cas9 promoter. When double-strand breaks (DSBs) are induced in the target gene sequence, the Cas9 promoter is cut off and transcription ceases. With this system, expression of Cas9 protein at 60 h after transfection is only 10% that of the wild-type system, with about 70% promoter deletion efficiency. The target site editing efficiency and homologous recombination efficiency of the self-restricting system remain at about 50% and 30%, respectively, while the frequency of off-target indel formation decreased by 76.7%. Further, the number of indel types was also reduced from 13 to 2. Because this system does not include additional gRNA sequences, the possibility of introducing new off-target mutations is decreased. Importantly, this system is composed of a single plasmid, which could potentially be easily introduced in vivo using a viral vector or nanoparticles.
- Published
- 2020
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