Efficient Mitochondrial Genome Editing by CRISPR/Cas9

Figure 3

Construction of mitochondria-targeted MTS-HA-Cas9. (a) Schematic illustration of mitochondria-targeting Cas9 (mitoCas9). Mitochondria-targeting sequence (MTS) and HA tag information are presented. (b) Expression of mitoCas9 in HEK-293T cells transiently transfected with MTS-HA-Cas9 construct determined by Western blots using HA antibody. β-actin was used as a loading control. (c) Subcellular localization of MTS-HA-Cas9 assessed in the cytosolic (Cyt), mitochondrial (Mit), and nuclear (Nu) fractions of HEK-293T cells transfected with lentiCRISPR-sgRNA-eGFP#2 and monitored by Western blot. GAPDH served as a cytosolic marker, PARP1 served as a nuclear marker, and SDHA served as a mitochondrial marker. (d) Representative immunofluorescence microscopic image of MTS-HA-Cas9 (HA, green) and CoxIV (red) subcellular distributions in HEK-293T cells transfected with MTS-HA-Cas9 construct. The merged image (yellow, right panel) shows colocalization of mitoCas9 and CoxIV. (e) Representative gel images of the PCR product of hU6-sgRMA-eGFP and hU6-sgRNA-Cox1 which were purified by gel extraction (bottom panel). Schematics of primers and lentiCRISPR-sgRNA templates used to amplify U6 promoter and respective sgRNA components for transfection (upper panel). (f) Quantification of copy numbers for Cox1, Cox3, and ND1 regions of mtDNA extracted from HEK-293T cells transiently transfected with indicated constructs (mitoCas9 is a plasmid, while U6-sgRNAs are PCR product.), determined by real-time quantitative PCR using primers listed in Table 2. GAPDH was used as an internal loading control ( per group). Quantified data (b) are expressed as mean ± s.e.m., , analysis of variance (ANOVA) test followed by Student-Newman-Keuls post hoc analysis.

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