SNGD-mediated gene editing of a mutated thymidine kinase 1 (TK1) gene. (A) Schematic of correction of the TK1 gene in the TSCER2 cell line. TSCER2 cells possess both exon 4- and exon 5-mutated alleles and are sensitive to CHAT medium. The single-nucleotide insertion in exon 4 (indicated in red) was targeted to correct the TK1 gene. When the mutation in exon 4 was edited to recover TK activity, the cells acquired CHAT-medium resistance. The PAM sequence is indicated by a box. The sgRNA target sequence is underlined. Nick sites in the TK1 gene and donor plasmid are indicated by the blue V mark. (B) Percentages of CHAT-medium-resistant cells are indicated (mean ± SD, N = 3). (C) Summary of sequence analysis of exon 4 of the TK1 gene in CHAT-medium-resistant cell clones.
