CRISPR-Cas3
Genome-editing
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editing technology Possibilities of Genome -
CRISPR-Cas3
Strengths of CRISPR-Cas3

CRISPR-Cas3 is a new genome editing technology discovered by a team led by Dr. Tomoji Mashimo (currently a professor at the Institute of Medical Science, University of Tokyo). This technology is characterized by the fact that no off-target mutations have been observed to date, which makes it highly safe. Additionally, it has the ability to delete the larger portion of the gene. Last but not least, CRISPR- Cas3 is not affected by the complex patent situation surrounding CRISPR-Cas9, the world-leading genome editing technology, positioning it as a promising alternative that could compete with CRISPR-Cas9.
①Greater Safety
CRISPR-Cas3 is a complex of Cas3 and Cascade (five different proteins with crRNA), which recognizes the target DNA sequence by crRNA. The crRNA contains a 27-nucleotide recognition sequence, making it more specific than CRISPR-Cas9, which has only 20-nucleotide recognition sequence (theoretically 4^7 higher specificity could be achieved by CRISPR-Cas3). As a result, off-target mutations (mutations occurring outside the target site) have not been observed by CRISPR-Cas3 to date, and a high level of safety is expected.

②Efficient Gene Editing by Large Deletion
The widely used CRISPR-Cas9 system cleaves double-stranded DNA at a single site, much like scissors. But the cleavage mechanism of the CRISPR-Cas3 system has been found to be different.
When the Cascade complex recognizes the target site, the Cas3 protein binds to it, unwinds the double-stranded DNA, and then cleaves each single-stranded DNA strand separately while pulling one strand apart. This unique mechanism enables the CRISPR-Cas3 system to perform large-scale editing, affecting hundreds to thousands of bases upstream of the target sequence.
As a result, a single CRISPR-Cas3 system can be used for gene editing in cases where extensive modifications are needed, such as when suppressing the expression of a target gene.
Mechanism of double-stranded DNA cleavage by CRISPR-Cas3

③IP for Freedome-To-Operate
Although genome editing holds vast potential and is expected to be applied across a wide range of fields, Freedom-To-Operate (FTO) is essential for its widespread use in industrial sectors. In this context, the CRISPR-Cas3 system is protected by an independent patent, providing FTO.
C4U has secured an exclusive worldwide license from Osaka University, the patent holder, for the foundational Cas3 patent titled "METHOD FOR MANUFACTURING DNA-EDITED EUKARYOTIC CELL, AND KIT USED IN METHOD”. This patent has already been issued in Japan, the U.S., China, Europe, and many other countries. Additionally, we are making steady progress in securing intellectual property rights for related inventions.
Reference Paper
- Nat Commun. 2019 doi: 10.1038/s41467-019- 13226-x.
- iScience 2022 doi: 10.1016/j.isci.2022.103830.
- Nat Commun. 2022 doi: 10.1038/s41467-022-32618-0
Collaborative Research Partners
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The Institute of Medical Science,
The University of Tokyo -
The Institute of Experimental Animal Sciences Faculty of Medicine ,
Osaka University -
RIKEN
SPring-8 Center -
Center for iPS,
Kyoto University -
Center for iPS Cell Research and Application,
Kyoto University -
National Center for Child Health and Development
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Kawasaki
Medical School -
Hiroshima University
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Celaid Therapeutics Inc.