Performance of CRISPR/SpCas9-eloxP System in Transient Reporter-Gene Expression Assays
(A) Schematic of the mT/mG cassette (loxP-mT-pA-loxP-mG-pA) before and after CRISPR/SpCas9-eloxP-mediated recombination. mT/mG consists of a promoter driving a loxP-flanked coding sequence of membrane-targeted tandem dimer Tomato (mT), resulting in mTomato expression with membrane localization. After CRISPR/SpCas9-eloxP-mediated recombination, the mTomato sequence is excised, allowing the promoter to drive expression of membrane-targeted EGFP (mG). (B) An illustration of the CRISPR/SpCas9-eloxP system in transient reporter-gene expression assays. (C) HEK293 cells were co-transfected with pmTmG and CRISPR/SpCas9-eloxP (0.75 ug each), and images were obtained at 48 hr post transfection (red indicates mT; green indicates mG). See also Figure S2. (D) The level of fluorescence was quantified (red indicates mT; green indicates mG). Error bars are SD (n = 3). The p value was calculated by Student’s t test; *p < 0.05. (E) NHEJ pattern of CRISPR/SpCas9-eloxP-mediated gene editing. Pink nucleotides indicate sgRNA. Blue nucleotides indicate indels.