The CRISPR (clustered regularly interspaced short palindromic repeat)-Cas (CRISPR-associated) nucleases have been widely applied for genome engineering. Cas9 (Streptococcus pyogenes Cas9 [SpCas9] and Staphylococcus aureus Cas9 [SaCas9]) and Cpf1 (i.e., Francisella novicida U112 Cpf1 [FnCpf1], also named FnCas12a) were harnessed to perform gene editing in human cells. Precise genetic modification by homology-directed repair (HDR) is an attractive approach for in situ gene correction. However, so far, the comparative efficiencies of HDR mediated by different CRISPR orthologs remain unknown. To address this question, in this study, we developed a reporter system to investigate HDR efficiencies triggered by various CRISPR orthologs. We found that SpCas9 and SaCas9, the two most commonly used Cas9 enzymes, possessed a similar ability to induce HDR. Interestingly, with the increasing amount of coding plasmids or additional nuclear localization sequences, FnCpf1 could improve the HDR efficacy. Collectively, our study provides insights for the rational selection of appropriate tools for human genome manipulation.

中文翻译：

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人类细胞中CRISPR-Cas触发同源定向修复的合理选择

CRISPR（成簇的规则间隔短回文重复序列）-Cas（CRISPR 相关）核酸酶已广泛应用于基因组工程。Cas9（化脓性链球菌Cas9 [SpCas9] 和金黄色葡萄球菌Cas9 [SaCas9]）和 Cpf1（即Francisella novicida U112 Cpf1 [FnCpf1]，也称为 FnCas12a）被用来在人类细胞中进行基因编辑。通过同源定向修复 (HDR) 进行精确的基因修饰是一种有吸引力的原位修复方法基因校正。然而，到目前为止，由不同 CRISPR 直系同源物介导的 HDR 的比较效率仍然未知。为了解决这个问题，在这项研究中，我们开发了一个报告系统来调查由各种 CRISPR 直系同源物触发的 HDR 效率。我们发现 SpCas9 和 SaCas9 这两种最常用的 Cas9 酶具有相似的诱导 HDR 的能力。有趣的是，随着编码质粒或额外核定位序列数量的增加，FnCpf1 可以提高 HDR 功效。总的来说，我们的研究为合理选择用于人类基因组操作的适当工具提供了见解。