Aptazyme-mediated direct modulation of post-transcriptional sgRNA level for conditional genome editing and gene expression.

RNA-guided endonuclease Cas9 derived from microbial CRISPR-Cas adaptive immune systems is a powerful tool for genome editing, which has been widely used in eukaryotic systems, prokaryotic systems, and plants. However, the off-target effects caused by Cas9/sgRNA remain a major concern. Currently, the efforts to reduce the off-target effects mainly focus on improving the targeting specificity of sgRNA/Cas9, regulating the activity of the Cas9 protein or the sgRNA, and controlling the time window of their expression. In this study, a novel system was established to regulate the post-transcriptional sgRNA level by small molecule-controlled aptazyme. This system was shown to reduce the off-target effects caused by Cas9/sgRNA, while enabling precise temporal control over gene editing and regulatory activity. This new system could provide a potentially safer and more powerful tool for genome editing and therapeutic application.