The CRISPR-Cas9 for genome editing, which has been developed in 2012, won the 2020 Nobel Prize in Chemistry. The genome editing technology enabled us to implement genetic modification in a variety of species and cells. We have established several strategies for generating genetically modified mice and rats as human disease models by using this tool. On the other hand, the technology has been also used in a variety of applied research fields such as industry, agriculture, and medicine. However, there are several limitations about technical issues of safety and design of it, as well as intellectual property issues.

Class 2 CRISPR systems, including type II Cas9 and type V Cas12a, are the most commonly used for genome editing in eukaryotic cells, while type I CRISPR systems within Class 1 are also becoming available. We have applied the CRISPR-Cas3 derived from E. coli, which belongs to class 1 CRISPR system, for gene modification and established it as a novel genome editing technology in human cells. Type I CRISPR recognizes longer target sequences than CRISPR-Cas9 and can induce large deletion mutations of several kilobases. These features demonstrate its potential as a unique genome editing tool that can induce genetic disruption safely and reliably. Recently, the DNA cleavage mechanism of type I CRISPR has revealed the single-strand DNA trans-cleavage activity of type I CRISPR, called collateral activity, which has broadened the potential application for CRISPR diagnostics, especially in the development of point-of-care testing methods for COVID-19. Here, I would like to present an overview of the type I-E CRISPR system, its application to genome editing, and genetic diagnosis.

References:

・ Dynamic mechanisms of CRISPR interference by Escherichia coli CRISPR-Cas3. Yoshimi K, et al., Nat Commun. 2022 Aug 30;13(1):4917.

・ CRISPR-Cas3-based diagnostics for SARS-CoV-2 and influenza virus. Yoshimi K, et al., iScience. 2022 Feb 18;25(2):103830.

・ CRISPR-Cas3 induces broad and unidirectional genome editing in human cells. Morisaka H et al., Nat Commun. 2019 Dec 6;10(1):5302.

・ Combi-CRISPR: combination of NHEJ and HDR provides efficient and precise plasmid-based knock-ins in mice and rats Yoshimi K, et al., Hum Genet 2021 Feb;140(2):277-

287.

・ ssODN-mediated knock-in with CRISPR-Cas for large genomic regions in zygotes, Yoshimi K, et al., Nat Commun. 2016 Jan 20;7:10431.