Figure 1.

Schematic illustrations of the miR-Cas9 switch. (A) Design of miRNA-responsive Cas9 mRNA (miR-Cas9 switch). The synthetic mRNA contains an anti-reverse cap analog (yellow), miRNA target site (orange), Cas9 encoding sequence (cyan), and 120 nucleotide poly(A) tail. The miRNA target site is completely complementary to the miRNA of interest. (B) Overview of the miR-Cas9 switch system. The miR-Cas9 switch and sgRNA are introduced to cells by RNA transfection. Cas9 protein expressed from the mRNA forms a Cas9–sgRNA complex and digests the DNA in the case of no miRNA activity (ON, left). In contrast, in the case of high miRNA activity, interaction between the miRNA and Cas9 mRNA reduces Cas9 expression (OFF, right).