美国哈佛医学院J. Keith Joung课题组近期报道了一类具有更低RNA脱靶和自编辑活性的CRISPR DNA碱基编辑器。这一研究成果于2019年9月2日在线发表于《自然—生物技术》。
胞嘧啶或腺嘌呤碱基编辑（CBE或ABE）可以引入特定的DNA C-to-T或A-to-G改变。然而，研究人员最近证明它们还可以以不依赖向导RNA的方式诱导转录组范围的RNA碱基编辑，并由此构建了SECURE（selective curbing of unwanted RNA editing）-BE3变体，这些变体减少了不需要的RNA编辑活性。因此，研究人员在这项工作中报道了结构导向的SECURE-ABE变体加工，其具有降低的脱靶RNA编辑活性和相当的非脱靶DNA编辑活性，这也是迄今描述的最小的化脓性链球菌Cas9碱基编辑物之一。
研究人员还测试了除APOBEC1以外的胞苷脱氨酶的CBE，发现基于人APOBEC3A的CBE诱导RNA碱基的大量编辑，而基于APOBEC3A的增强CBE、基于人类激活诱导的胞苷脱氨酶的CBE和基于海七鳃鳗（Petromyzon marinus）胞苷脱氨酶的CBE（Target-AID）能够产生较少的RNA编辑。
最后，研究人员发现具有RNA脱靶编辑活性的CBE和ABE也可以自编辑它们自己的转录本，从而导致碱基编辑器编码序列的异质性。
附：英文原文
Title: CRISPR DNA base editors with reduced RNA off-target and self-editing activities
Author: Julian Grnewald, Ronghao Zhou, Sowmya Iyer, Caleb A. Lareau, Sara P. Garcia, Martin J. Aryee, J. Keith Joung
Issue&Volume: 2019-09-02
Abstract: Cytosine or adenine base editors (CBEs or ABEs) can introduce specific DNA C-to-T or A-to-G alterations1,2,3,4. However, we recently demonstrated that they can also induce transcriptome-wide guide-RNA-independent editing of RNA bases5, and created selective curbing of unwanted RNA editing (SECURE)-BE3 variants that have reduced unwanted RNA-editing activity5. Here we describe structure-guided engineering of SECURE-ABE variants with reduced off-target RNA-editing activity and comparable on-target DNA-editing activity that are also among the smallest Streptococcus pyogenes Cas9 base editors described to date. We also tested CBEs with cytidine deaminases other than APOBEC1 and found that the human APOBEC3A-based CBE induces substantial editing of RNA bases, whereas an enhanced APOBEC3A-based CBE6, human activation-induced cytidine deaminase-based CBE7, and the Petromyzon marinus cytidine deaminase-based CBE Target-AID4 induce less editing of RNA. Finally, we found that CBEs and ABEs that exhibit RNA off-target editing activity can also self-edit their own transcripts, thereby leading to heterogeneity in base-editor coding sequences.
DOI: 10.1038/s41587-019-0236-6
Source: https://www.nature.com/articles/s41587-019-0236-6
Nature Biotechnology：《自然—生物技术》，创刊于1996年。隶属于施普林格·自然出版集团，最新IF：68.164
官方网址：https://www.nature.com/nbt/
投稿链接：https://mts-nbt.nature.com/cgi-bin/main.plex
本期文章：《自然—生物技术》：Online/在线发表
