CRISPR-Cas9 has emerged as a major genome manipulation tool. As Cas9 can cause off-target effects, several methods for controlling the expression of CRISPR systems were developed. Recent studies have shown that CRISPR activity could be controlled by sensing expression levels of endogenous transcripts. This is particularly interesting, as endogenous RNAs could harbor important information about the cell type, disease state, and environmental challenges cells are facing. Single-guide RNA (sgRNA) engineering played a major role in the development of RNA-responsive CRISPR systems. Following further optimizations, RNA-responsive sgRNAs could enable the development of novel therapeutic and research applications. This review introduces engineering strategies that could be employed to modify Streptococcus pyogenes sgRNAs with a focus on recent advances made toward the development of RNA-responsive sgRNAs. Future directions and potential applications of these technologies are also discussed.

中文翻译：

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用于控制 CRISPR 活性的 RNA 响应性 gRNA：当前进展、未来方向和潜在应用

CRISPR-Cas9 已成为主要的基因组操作工具。由于Cas9会引起脱靶效应，因此开发了几种控制CRISPR系统表达的方法。最近的研究表明，CRISPR 活性可以通过检测内源转录本的表达水平来控制。这是特别有趣的，因为内源性 RNA 可能包含有关细胞类型、疾病状态和细胞面临的环境挑战的重要信息。单向导RNA（sgRNA）工程在RNA响应性CRISPR系统的开发中发挥了重要作用。经过进一步优化，RNA 响应 sgRNA 可以促进新型治疗和研究应用的开发。本综述介绍了可用于修饰化脓性链球菌的工程策略sgRNA，重点关注 RNA 响应 sgRNA 开发的最新进展。还讨论了这些技术的未来方向和潜在应用。