A CRISPR-based mitochondrial gene therapy tool derived by engineering guide RNAs

Mitochondrial genetic diseases arise from mitochondrial DNA (mtDNA) defects, which gene therapy tools may rectify. However, delivering single-guide RNAs (sgRNAs) into mitochondria remains a challenge limiting CRISPR-mediated mtDNA therapy. Here, through network analysis of mitochondrion-localized long noncoding RNAs (lncRNAs) and RNA-binding proteins (RBPs), we found that lncRNA RP11-46H11.3 translocates into mitochondria via binding mitochondria-associated RBPs using its key RNA recognition motifs (RRMs); its derived 30 nt ST2-RNA mitochondrial targeting sequence (RMTS) showed the highest mitochondrial localization efficiency. We engineered the RMTS-CRISPR tool by fusing ST2-RMTS to sgRNA, verifying its ability to target and cleave mtDNA. Strikingly, our results demonstrated that RMTS-CRISPR could achieve heteroplasmic mtDNA shifting efficiencies of up to 26.37% in m.3243A>G mutant cell models and 26.79% in vivo, offering a technological approach for the correction of heterogeneous mtDNA mutations. Taken together, our findings reveal a CRISPR-based mitochondrial gene intervention strategy that may have applications in mitochondrial disorders.