Department of Therapeutic Radiology, Yale School of Medicine, New Haven, Connecticut, USA.
Department of Genetics, Yale School of Medicine, New Haven, Connecticut, USA.
Nucleic Acid Ther. 2024 Oct;34(5):245-256. doi: 10.1089/nat.2024.0007. Epub 2024 Jul 22.
Although CRISPR-Cas9 gene therapies have proven to be a powerful tool across many applications, improvements are necessary to increase the specificity of this technology. Cas9 cutting in off-target sites remains an issue that limits CRISPR's application in human-based therapies. Treatment of autosomal dominant diseases also remains a challenge when mutant alleles differ from the wild-type sequence by only one base pair. Here, we utilize synthetic peptide nucleic acids (PNAs) that bind selected spacer sequences in the guide RNA (gRNA) to increase Cas9 specificity up to 10-fold. We interrogate variations in PNA length, binding position, and degree of homology with the gRNA. Our findings reveal that PNAs bound in the region distal to the protospacer adjacent motif (PAM) site effectively enhance specificity in both on-target/off-target and allele-specific scenarios. In addition, we demonstrate that introducing deliberate mismatches between PNAs bound in the PAM-proximal region of the gRNA can modulate Cas9 activity in an allele-specific manner. These advancements hold promise for addressing current limitations and expanding the therapeutic potential of CRISPR technology.
尽管 CRISPR-Cas9 基因疗法已被证明在许多应用中是一种强大的工具，但仍需要改进以提高该技术的特异性。Cas9 在脱靶位点的切割仍然是限制 CRISPR 在基于人类的治疗中的应用的一个问题。当突变等位基因与野生型序列仅相差一个碱基时，常染色体显性疾病的治疗仍然是一个挑战。在这里，我们利用与向导 RNA（gRNA）中选定的间隔序列结合的合成肽核酸（PNA），将 Cas9 的特异性提高了 10 倍。我们研究了 PNA 长度、结合位置和与 gRNA 的同源性的变化。我们的研究结果表明，在 PAM 位点远端结合的 PNA 有效地增强了靶标/脱靶和等位基因特异性两种情况下的特异性。此外，我们证明了在 gRNA 的 PAM 近端区域结合的 PNA 之间引入故意错配可以以等位基因特异性的方式调节 Cas9 的活性。这些进展有望解决当前的限制，并扩大 CRISPR 技术的治疗潜力。
