Targeted deletions in human mitochondrial DNA engineered by Type V CRISPR-Cas12a system.

Mutations in mitochondrial DNA (mtDNA) contribute to various neuromuscular diseases, with severity depending on heteroplasmy level when mutant and wild-type mtDNA coexist within the same cell. Developing methods to model mtDNA dysfunction is crucial for experimental therapies. Here, we adapted the Type V CRISPR-AsCas12a system, which recognizes AT-rich PAM sequences, for targeted editing of human mtDNA. We demonstrated that mitochondrial targeting sequence (MTS) from Neurospora crassa ATPase subunit 9 efficiently addressed the AsCas12a effector nuclease into human mitochondria. When programmed with two CRISPR RNAs (crRNAs) targeting distant regions of mtDNA, the mito-AsCas12a can cleave mtDNA, enabling generation of deletions in cultured human cells. Next generation sequencing of the deletions boundaries confirmed mtDNA ligation after the cleavage by the mitoCRISPR-AsCas12a system. Therefore, we provide experimental data proving that a CRISPR system has potential to be used for precise mtDNA manipulation, offering a promising tool for generating predefined deletions in mtDNA and creating cellular models of mitochondrial disorders.