基于CRISPR/Cas系统的DNA碱基编辑技术及其在生物医学和农业中的应用

CRISPR/Cas-mediated DNA base editing technology and its application in biomedicine and agriculture

摘要:

近年来，基于成簇的规律间隔短回文重复序列及其相关系统 (Clustered regularly interspaced short palindromic repeats/CRISPR-associated protein，CRISPR/Cas) 的基因编辑技术飞速发展，该系统可以利用同源定向重组 (Homology directed repair，HDR) 来完成其介导的精准编辑，但效率极低，限制了其在农业和生物医学等领域上的推广应用。基于CRISPR/Cas系统的DNA碱基编辑技术作为一种新兴的基因组编辑技术，能在不产生双链断裂的情况下实现碱基的定向突变，相对于CRISPR/Cas介导的HDR编辑具有更高的编辑效率和特异性。目前，已开发出了可将C碱基突变为T碱基的胞嘧啶碱基编辑器 (Cytidine base editors，CBE)，将A碱基突变为G碱基的腺嘌呤碱基编辑器 (Adenine base editors，ABE)，以及可实现碱基任意变换和小片段精准插入和缺失的Prime编辑器 (Prime editors，PE)。另外，能实现C到G颠换的糖基化酶碱基编辑器 (Glycosylase base editors，GBE) 以及能同时编辑A和C两种底物的双碱基编辑器也已被开发出来。文中主要综述了几种DNA碱基编辑器的开发历程、研究进展及各自优点和局限性；介绍了DNA碱基编辑技术在生物医学以及农业中的成功应用案例，以期为DNA碱基编辑器的进一步优化和选择应用提供借鉴。

Abstract:

In recent years, the genome editing technologies based on the clustered regularly interspaced short palindromic repeats/CRISPR-associated protein (CRISPR/Cas) have developed rapidly. The system can use homologous directed recombination (HDR) to achieve precise editing that it medicated, but the efficiency is extremely low, which limits its application in agriculture and biomedical fields. As an emerging genome editing technology, the CRISPR/Cas-mediated DNA base editing technologies can achieve targeted mutations of bases without generating double-strand breaks, and has higher editing efficiency and specificity compared with CRISPR/Cas-mediated HDR editing. At present, cytidine base editors (CBEs) that can mutate C to T, adenine base editors (ABEs) that can mutate A to G, and prime editors (PEs) that enable arbitrary base conversion and precise insertion and deletion of small fragments, have been developed. In addition, glycosylase base editors (GBEs) capable of transitioning from C to G and double base editors capable of editing both A and C simultaneously, have been developed. This review summarizes the development, advances, advantages and limitations of several DNA base editors. The successful applications of DNA base editing technology in biomedicine and agriculture, together with the prospects for further optimization and selection of DNA base editors, are discussed.