Cell：让“DNA剪刀”变身“RNA手术刀”！可爱龙团队将Cas9及其祖先转变为RNA编辑器

Core Viewpoint - The research presents a novel RNA editing tool, R-IscB, engineered from the Cas9 ancestor IscB, which offers a safer and more efficient alternative to existing RNA editing technologies like Cas13, addressing the limitations of current methods in clinical applications [3][4][16]. Group 1: RNA Editing Technology - CRISPR-Cas9 has revolutionized genome medicine but poses irreversible DNA editing risks, limiting its clinical use [3]. - RNA editing is a safer alternative due to its transient and reversible nature, but existing tools like CRISPR-Cas13 face significant challenges, including off-target effects and cellular toxicity [3][4]. - The study by Yale University transformed IscB and Cas9 into RNA-guided RNA editors, demonstrating potential applications in splice interference, trans-splicing, and RNA base editing [4][16]. Group 2: Engineering and Mechanism - The research team engineered IscB by removing its TID/PID domains, converting it into R-IscB, which retains the ability to recognize single-stranded DNA/RNA while losing its double-stranded DNA cutting capability [8][14]. - R-IscB exhibits a strong affinity for single-stranded RNA, surpassing Cas13 in performance [8][12]. Group 3: Applications and Efficacy - R-IscB has shown effectiveness in various applications: 1. RNA splicing regulation, significantly reducing pathogenic mRNA levels [10]. 2. Trans-splicing capabilities to correct mutations in mRNA, potentially simplifying treatments for complex genetic disorders [11]. 3. RNA base editing for precise single nucleotide changes, useful for correcting disease-causing mutations [11]. 4. RNA degradation through enhanced cutting activity, effectively lowering target mRNA levels [11]. Group 4: Advantages Over Cas13 - R-IscB presents several disruptive advantages compared to Cas13: 1. Zero toxicity, with no observed cell death or morphological abnormalities in treated cells [13]. 2. Superior activity in splicing regulation and RNA cutting [13]. 3. Smaller size, facilitating easier delivery via AAV viral vectors for in vivo RNA editing [13]. 4. Versatility, as the same engineering strategy successfully enhanced RNA editing capabilities in multiple Cas9 variants [13][14].