小柯机器人

北京大学伊成器团队发现，线粒体碱基编辑器可诱发大量的核内脱靶突变。相关论文于2022年5月12日在线发表在《自然》杂志上。

据研究人员介绍，DddA衍生的胞嘧啶碱基编辑（DdCBE）是分割的DddA两半和转录激活剂样效应器（TALE）阵列蛋白的融合，使线粒体DNA中的C-G到T-A有针对性地转换。然而，其在全基因组范围内的特异性却不甚了解。

研究人员表明，线粒体碱基编辑在核基因组中诱导广泛的脱靶编辑。在全基因组范围内，对其编辑组的无偏分析显示了数百个依赖或不依赖TALE阵列序列（TAS）的脱靶位点。核DNA（nDNA）中依赖TAS的脱靶位点通常只由两个TALE重复序列中的一个指定，这对DdCBE由定位在近处的成对TALE蛋白引导的原则构成挑战。与TAS无关的nDNA脱靶点经常在具有不同TALE阵列的DdCBE中共享。

值得注意的是，它们与CTCF结合位点有强烈的共定位，并在TAD边界富集。研究人员还设计了DdCBE来减轻这种脱靶效应。总的来说，这些结果对DdCBE在基础研究和治疗应用中的使用有影响，并表明需要彻底定义和评估碱基编辑工具的脱靶效应。

附：英文原文

Title: Mitochondrial base editor induces substantial nuclear off-target mutations

Author: Lei, Zhixin, Meng, Haowei, Liu, Lulu, Zhao, Huanan, Rao, Xichen, Yan, Yongchang, Wu, Hao, Liu, Min, He, Aibin, Yi, Chengqi

Issue&Volume: 2022-05-12

Abstract: DddA-derived cytosine base editors (DdCBEs), which are fusions of the split-DddA halves and transcription activator-like effector (TALE) array proteins, enable targeted C·G-to- T·A conversions in mitochondrial DNA1. However, its genome-wide specificity is poorly understood. Here we show that the mitochondrial base editor induces extensive off-target editing in the nuclear genome. Genome-wide, unbiased analysis of its editome reveals hundreds of off-target sites that are TALE array sequence (TAS)-dependent or -independent. TAS-dependent off-target sites in the nuclear DNA (nDNA) are often specified by only one of the two TALE repeats, challenging the principle that DdCBEs are guided by a paired TALE proteins positioned in close proximity. TAS-independent nDNA off-target sites are frequently shared among DdCBEs with distinct TALE arrays. Notably, they co-localize strongly with CTCF-binding sites and are enriched in TAD boundaries. We also engineered DdCBE to alleviate such off-target effect. Collectively, our results have implications for the use of DdCBEs in basic research and therapeutic applications, and suggest the need to thoroughly define and evaluate the off-target effects of base editing tools.

DOI: 10.1038/s41586-022-04836-5

Source: https://www.nature.com/articles/s41586-022-04836-5

Nature：《自然》，创刊于1869年。隶属于施普林格·自然出版集团，最新IF：69.504
官方网址：http://www.nature.com/
投稿链接：http://www.nature.com/authors/submit_manuscript.html